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Priyadarshini E, Minzar M, Pandey S, Rawat K. Synergistic reduction of nitrophenols by Au-CDs nanoconjugates with NaBH 4. Nanotechnology 2024; 35:275101. [PMID: 38502954 DOI: 10.1088/1361-6528/ad355a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 03/19/2024] [Indexed: 03/21/2024]
Abstract
Developing sustainable and innovative approaches for the efficient reduction of nitrophenols is crucial for environmental remediation, for managing health concerns posed by their widespread presence as hazardous pollutants in industrial effluents and contaminated water. We report the use of 12.9 ± 1 nm (TEM data) sized gold carbon dot nanoconjugates (Au@CDs) for catalytic conversion of o, m, p-nitrophenols to aminophenols by sodium borohydride. A simple approach was followed to synthesize ultra-small and highly stable Au@CDs, using citric acid and PEG as reducing and stabilizing agents. X-ray diffraction analysis verified the formation of nano-crystalline nanoconjugates. These nanoconjugates showed a remarkable catalytic activity in the range of 0.22-0.33 s-1(varying with nanoconjugate concentration) which was much higher compared to conventional chemical methods of reduction. All the catalytic reaction experiments were performed at room temperature (27 ± 2 °C). Furthermore, an increase in rate constant was observed with increasing concentration of nanoconjugates. The catalytic activity of Au@CDs nanoconjugates was observed to be in order of m-nitrophenol > o-nitrophenol > p-nitrophenol with apparent rate constant (kaap) values of 0.068, 0.043 and 0.031, respectively. Comparative analysis with GNPs, CDs and Au@CDs nanoconjugates stated that the nanoconjugates had superior catalytic activity. The research can have significant implications in the development of new strategies for environmental remediation and biomedical applications.
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Affiliation(s)
| | - Mohd Minzar
- Department of Chemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
| | - Saurabh Pandey
- Department of Biochemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
| | - Kamla Rawat
- Department of Chemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, India
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2
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Saad NS, Mashali MA, Repas SJ, Janssen PML. Altering Calcium Sensitivity in Heart Failure: A Crossroads of Disease Etiology and Therapeutic Innovation. Int J Mol Sci 2023; 24:17577. [PMID: 38139404 PMCID: PMC10744146 DOI: 10.3390/ijms242417577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 12/24/2023] Open
Abstract
Heart failure (HF) presents a significant clinical challenge, with current treatments mainly easing symptoms without stopping disease progression. The targeting of calcium (Ca2+) regulation is emerging as a key area for innovative HF treatments that could significantly alter disease outcomes and enhance cardiac function. In this review, we aim to explore the implications of altered Ca2+ sensitivity, a key determinant of cardiac muscle force, in HF, including its roles during systole and diastole and its association with different HF types-HF with preserved and reduced ejection fraction (HFpEF and HFrEF, respectively). We further highlight the role of the two rate constants kon (Ca2+ binding to Troponin C) and koff (its dissociation) to fully comprehend how changes in Ca2+ sensitivity impact heart function. Additionally, we examine how increased Ca2+ sensitivity, while boosting systolic function, also presents diastolic risks, potentially leading to arrhythmias and sudden cardiac death. This suggests that strategies aimed at moderating myofilament Ca2+ sensitivity could revolutionize anti-arrhythmic approaches, reshaping the HF treatment landscape. In conclusion, we emphasize the need for precision in therapeutic approaches targeting Ca2+ sensitivity and call for comprehensive research into the complex interactions between Ca2+ regulation, myofilament sensitivity, and their clinical manifestations in HF.
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Affiliation(s)
- Nancy S. Saad
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA;
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Helwan University, Cairo 11795, Egypt
| | - Mohammed A. Mashali
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA;
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
- Department of Surgery, Faculty of Veterinary Medicine, Damanhour University, Damanhour 22514, Egypt
| | - Steven J. Repas
- Department of Emergency Medicine, Wright State University Boonshoft School of Medicine, Dayton, OH 45324, USA;
| | - Paul M. L. Janssen
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH 43210, USA;
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
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3
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Lokesh S, Lard ML, Cook RL, Yang Y. Critical Role of Semiquinones in Reductive Dehalogenation. Environ Sci Technol 2023; 57:14218-14225. [PMID: 37668505 DOI: 10.1021/acs.est.3c03981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Quinones and products of their redox reactions (hydroquinones and semiquinones) have been suggested as important players in the reductive dehalogenation of organohalogens mediated by natural and pyrogenic organic matter, although based on limited direct evidence. This study focused on the reductive dehalogenation of a model organohalogen (triclosan) by 1,4-benzohydroquinone (H2Q). In the presence of H2Q only, degradation of triclosan does not occur within the experimental period (up to 288 h); however, it takes place in the presence of H2Q and FeCl3 under anoxic conditions at pH 5 and 7 (above the pKa of SQ = 4.1) only to be halted in the presence of dissolved oxygen. Kinetic simulation and thermodynamic calculations indicated that benzosemiquinone (SQ-) is responsible for the reductive degradation of triclosan, with the fitted rate constant for the reaction between SQ- and triclosan being 317 M-2 h-1. The critical role of semiquinones in reductive dehalogenation can be relevant to a wide range of quinones in natural and engineering systems based on the reported oxidation-reduction potentials of quinones/semiquinones and semiquinones/hydroquinones and supported by experiments with additional model hydroquinones.
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Affiliation(s)
- Srinidhi Lokesh
- Department of Civil and Environmental Engineering, University of Nevada, Reno, 1664 N. Virginia Street, Reno, Nevada 89557, United States
| | - Myron L Lard
- Department of Chemistry, Louisiana State University, 307 Choppin Hall, Baton Rouge, Louisiana 70803, United States
| | - Robert L Cook
- Department of Chemistry, Louisiana State University, 307 Choppin Hall, Baton Rouge, Louisiana 70803, United States
| | - Yu Yang
- Department of Civil and Environmental Engineering, University of Nevada, Reno, 1664 N. Virginia Street, Reno, Nevada 89557, United States
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4
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Heine PA, Borduas-Dedekind N. The Ozonolysis of Methylated Selenide Compounds in the Atmosphere: Isotopes, Kinetics, Products, and Mechanisms. Environ Sci Technol 2023; 57:13079-13087. [PMID: 37603774 DOI: 10.1021/acs.est.3c01586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Selenium (Se) is an essential micronutrient with an important atmospheric component in its biogeochemical cycle. In this cycle, phytoplankton form volatile organic Se species, such as dimethyl selenide (CH3SeCH3) and dimethyl diselenide (CH3SeSeCH3), which are emitted into the atmosphere. To predict the atmospheric fate of these methylated Se compounds, we investigated their ozonolysis reaction. We used proton-transfer-reaction time-of-flight mass spectrometry to quantify atmospheric Se and its isotopes, and used this method in kinetic and product studies. The ozonolysis of CH3SeCH3 proceeded with a rate constant of (7.4 ± 2.2) × 10-17 cm3 molec-1 s-1 at 26 ± 1 °C with an activation energy of 50 ± 14 kJ mol-1 forming dimethyl selenoxide (CH3Se(O)CH3). Comparatively, CH3SeSeCH3 reacted with O3 at (2.6 ± 0.9) × 10-17 cm3 molec-1 s-1 at 27 ± 1 °C with an activation energy of 56 ± 5 kJ mol-1 forming methylselinic acid (CH3Se(O)OH). At 20 ppbv of O3, the atmospheric lifetimes of CH3SeCH3 and CH3SeSeCH3 are 7.6 and 22 h, respectively. The Se oxidation products were confirmed by synthesis and can serve as new atmospheric tracers of methylated Se compounds. Overall, we measured Se isotopes in real time and determined the rate constants, activation energies, and oxidation products. These mechanisms can now be used to determine the quantitative atmospheric fate of Se toward O3, and thus its distribution within a changing climate.
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Affiliation(s)
- Paul A Heine
- Department of Chemistry, University of British-Columbia, Vancouver, BC V6T 1Z1, Canada
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Hiroyasu Y, Higashiguchi K, Shirakata C, Sugimoto M, Matsuda K. Kinetic Analysis of the Photochemical Paths in Asymmetric Diarylethene Dimer. Chemistry 2023; 29:e202300126. [PMID: 37246241 DOI: 10.1002/chem.202300126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/19/2023] [Accepted: 05/26/2023] [Indexed: 05/30/2023]
Abstract
An asymmetric diarylethene dimer composed of 2- and 3-thienylethene units linked by m-phenylene developed various colors upon UV irradiation via an independent photochromic reaction on each unit. The change in contents and the other photoresponses of the photogenerated four isomers were analyzed using quantum yield for all the possible photochemical paths, i. e., photoisomerization, fluorescence, energy transfer, and the other non-radiative paths. Almost all the rate constants of photochemical paths were calculated using measurable quantum yields and lifetimes. It was found that a significant contribution on photoresponse was the competition between photoisomerization and intramolecular energy transfer. The clear difference was observed in the photoresponses of the dimer and the 1 : 1 mixture solution of the model compounds. The m-phenylene spacer appropriately regulated the rate of energy transfer in the asymmetric dimer, and the spacer enabled isolation of the excited state of the dimer, making the above quantitative analysis possible.
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Affiliation(s)
- Yae Hiroyasu
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Kenji Higashiguchi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Chihiro Shirakata
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Masataka Sugimoto
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
| | - Kenji Matsuda
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
- Fukui Institute for Fundamental Chemistry, Kyoto University, Takano Nishibiraki-cho 34-4, Sakyo-ku, Kyoto, 606-8103, Japan
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Gerasimova E, Salimgareeva E, Magasumova D, Ivanova A. Kinetic Potentiometry as a Method for Studying the Interactions of Antioxidants with Peroxyl Radicals. Antioxidants (Basel) 2023; 12:1608. [PMID: 37627605 PMCID: PMC10451547 DOI: 10.3390/antiox12081608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 08/01/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
This work presents a new method using kinetic potentiometry to study the thermodynamic and kinetic parameters of the reactions of antioxidants with peroxyl radicals. The rate constants of the reaction of antioxidants with radicals have been determined, and the groups of "fast" and "slow" antioxidants have been conventionally distinguished. Fast antioxidants include ascorbic, uric, gallic, chlorogenic, caffeic acids, glutathione, L-cysteine, and catechol with constant values from (1.05-9.25) × 103 M·s-1; "slow" antioxidants are α-tocopherol (in aqueous media), ionol, 2,6-ditretbutylphenol, and compounds of the azoloazine series, modified with polyphenolic fragments, with constant values from (4.00-8.50) × 102 M·s-1. It is shown that the value of the rate constant is directly related to the type of kinetic dependence of the potential recorded when an antioxidant is introduced into the solution of the radical initiator. It is shown that the method with the determination of the induction period is difficult in the study of "slow" antioxidants. It has been established that the area above the curve of the kinetic dependence Exp(∆E) is directly related to the amount of inhibited peroxyl radicals and can be used to assess the inhibitory properties of an antioxidant from a thermodynamic point of view. "Fixed time method" and "Initial rate method" were used. Positive correlations between the described method have been established. The utility of the parameter of the area above the curve of the kinetic dependence Exp(∆E) in the study of objects of complex composition is shown.
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Affiliation(s)
| | | | | | - Alla Ivanova
- Analytical Chemistry Department, Institute of Chemical Engineering, Ural Federal University, 19 Mira Str., 620002 Ekaterinburg, Russia; (E.G.); (E.S.); (D.M.)
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7
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Rerick MT, Chen J, Weber SG. Electroosmotic Perfusion, External Microdialysis: Simulation and Experiment. ACS Chem Neurosci 2023. [PMID: 37379416 PMCID: PMC10360060 DOI: 10.1021/acschemneuro.3c00057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023] Open
Abstract
Information about the rates of hydrolysis of neuropeptides by extracellular peptidases can lead to a quantitative understanding of how the steady-state and transient concentrations of neuropeptides are controlled. We have created a small microfluidic device that electroosmotically infuses peptides into, through, and out of the tissue to a microdialysis probe outside the head. The device is created by two-photon polymerization (Nanoscribe). Inferring quantitative estimates of a rate process from the change in concentration of a substrate that has passed through tissue is challenging for two reasons. One is that diffusion is significant, so there is a distribution of peptide substrate residence times in the tissue. This affects the product yield. The other is that there are multiple paths taken by the substrate as it passes through tissue, so there is a distribution of residence times and thus reaction times. Simulation of the process is essential. The simulations presented here imply that a range of first order rate constants of more than 3 orders of magnitude is measurable and that 5-10 min is required to reach a steady state value of product concentration following initiation of substrate infusion. Experiments using a peptidase-resistant d-amino acid pentapeptide, yaGfl, agree with simulations.
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Affiliation(s)
- Michael T Rerick
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jun Chen
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Stephen G Weber
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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8
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Roy M, Kaur A, Alam A, Aslam M. BiOBr Surface-Functionalized Halide Double-Perovskite Films for Slow Ion Migration and Improved Stability. ACS Appl Mater Interfaces 2023; 15:18473-18481. [PMID: 36976570 DOI: 10.1021/acsami.3c00369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Surface-tailored lead-free halide double-perovskite (Cs2AgBiX6) thin films are utilized for ion migration studies. A thin surface layer of BiOBr/Cl is grown via intentional annealing of the halide films in ambient conditions. Herein, we physically stacked the two films, viz., Cs2AgBiBr6 and Cs2AgBiCl6, to thermally activate the halide ion migration at different temperatures (room temperature (RT)-150 °C). While annealing, the films' color changes from orange to pale yellow and transparent brown to yellow as a result of the migration of Br- ions from Cs2AgBiBr6 to Cs2AgBiCl6 and Cl- ions from Cs2AgBiCl6 to Cs2AgBiBr6, respectively. Annealing helps in homogenizing the halide ions throughout the films, consequently leading to a mixed phase, i.e., Cs2AgBiClxBr6-x/Cs2AgBiBrxCl6-x (x = 0 to 6) formation. The movement of ions is understood by absorption studies performed at regular time intervals. These investigations reveal a redshift (from 366 to 386 nm) and a blueshift (from 435 to 386 nm) in absorption spectra, indicating the migration of Br- and Cl- toward Cs2AgBiCl6 and Cs2AgBiBr6, respectively. The films characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) reveal the presence of a peak at 2θ = 10.90° and binding energy of 158.1 eV, respectively, corresponding to the formation of Bi-O bonds at the film surface. Also, XRD studies show a lower 2θ shift of the diffraction peak in the case of Cs2AgBiCl6 films and a higher 2θ shift in the case of Cs2AgBiB6 films, which further confirms the migration of Cl- and Br- from one film to the other. XPS investigations confirm the compositional change with a gradual increment in the concentration of Br-/Cl- with an increase in heating time for Cs2AgBiCl6/Cs2AgBiBr6 films. All these studies confirm thermal diffusion of halide ions in double-perovskite films. Further, from the exponential decay of the absorption spectra, the rate constant for halide (Br) ion diffusion is calculated, which shows an increment from 1.7 × 10-6 s-1 at RT to 12.1 × 10-3 s-1 at 150 °C. The temperature-dependent rate constant follows Arrhenius behavior and renders an activation energy of 0.42 eV (0.35 eV) for bromide (chloride) ion mobility. A larger estimated value as compared to the reported values for Cs2AgBiBr6 wafers (∼0.20 eV) reveals a slow mobility of halide ions in thin films of Cs2AgBiBr6/Cl6. The formation of a BiOBr passivation layer at the surface of Cs2AgBiBr6 thin film might be one of the plausible causes of the slow anion diffusion in the present work. Slow ion migration is an indication that the films are stable and of high-quality.
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Affiliation(s)
- Mrinmoy Roy
- Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Amandeep Kaur
- Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Aftab Alam
- Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - M Aslam
- Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
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Murillo-Gelvez J, Hickey K, Di Toro DM, Allen HE, Carbonaro RF, Chiu PC. Electron Transfer Energy and Hydrogen Atom Transfer Energy-Based Linear Free Energy Relationships for Predicting the Rate Constants of Munition Constituent Reduction by Hydroquinones. Environ Sci Technol 2023; 57:5284-5295. [PMID: 36961098 DOI: 10.1021/acs.est.2c08931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
No single linear free energy relationship (LFER) exists that can predict reduction rate constants of all munition constituents (MCs). To address this knowledge gap, we measured the reduction rates of MCs and their surrogates including nitroaromatics [NACs; 2,4,6-trinitrotoluene (TNT), 2,4-dinitroanisole (DNAN), 2-amino-4,6-dinitrotoluene (2-A-DNT), 4-amino-2,6-dinitrotoluene (4-A-DNT), and 2,4-dinitrotoluene (DNT)], nitramines [hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and nitroguanidine (NQ)], and azoles [3-nitro-1,2,4-triazol-5-one (NTO) and 3,4-dinitropyrazole (DNP)] by three dithionite-reduced quinones (lawsone, AQDS, and AQS). All MCs/NACs were reduced by the hydroquinones except NQ. Hydroquinone and MC speciations were varied by controlling pH, permitting the application of a speciation model to determine second-order rate constants (k) from observed pseudo-first-order rate constants. The intrinsic reactivity of MCs (oxidants) decreased upon deprotonation, while the opposite was true for hydroquinones (reductants). The rate constants spanned ∼6 orders of magnitude in the order NTO ≈ TNT > DNP > DNT ≈ DNAN ≈ 2-A-DNT > DNP- > 4-A-DNT > NTO- > RDX. LFERs developed using density functional theory-calculated electron transfer and hydrogen atom transfer energies and reported one-electron reduction potentials successfully predicted k, suggesting that these structurally diverse MCs/NACs are all reduced by hydroquinones through the same mechanism and rate-limiting step. These results increase the applicability of LFER models for predicting the fate and half-lives of MCs and related nitro compounds in reducing environments.
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Affiliation(s)
- Jimmy Murillo-Gelvez
- Department of Civil and Environmental Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Kevin Hickey
- Department of Civil and Environmental Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Dominic M Di Toro
- Department of Civil and Environmental Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Herbert E Allen
- Department of Civil and Environmental Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Richard F Carbonaro
- Department of Chemical Engineering, Manhattan College, Riverdale, New York 10471, United States
- Mutch Associates LLC, Ramsey, New Jersey 07446, United States
| | - Pei C Chiu
- Department of Civil and Environmental Engineering, University of Delaware, Newark, Delaware 19716, United States
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10
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Díaz Ó, Martín V, Renault P, Romero D, Guillamon A, Giraldo J. Allosteric binding cooperativity in a kinetic context. Drug Discov Today 2023; 28:103441. [PMID: 36372329 DOI: 10.1016/j.drudis.2022.103441] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/02/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
Allosteric modulators are of prime interest in drug discovery. These drugs regulate the binding and function of endogenous ligands, with some advantages over orthosteric ligands. A typical pharmacological parameter in allosteric modulation is binding cooperativity. This property can yield unexpected but illuminating results when decomposed into its kinetic parameters. Using two reference models (the allosteric ternary complex receptor model and a heterodimer receptor model), a relationship has been derived for the cooperativity rate constant parameters. This relationship allows many combinations of the cooperativity kinetic parameters for a single binding cooperativity value obtained under equilibrium conditions. This assessment may help understand striking experimental results involving allosteric modulation and suggest further investigations in the field.
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11
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Nashed O, Partoon B, Lal B, Sabil KM, Yaqub S, Shariff AM. Methane and Carbon Dioxide Hydrate Formation in the Presence of Metal-Based Fluid. Materials (Basel) 2022; 15:8670. [PMID: 36500166 PMCID: PMC9738816 DOI: 10.3390/ma15238670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/27/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Hydrate-based technology has yet to find its way to commercial applications due to several issues, including formation conditions and slow kinetics. Several solid particles were introduced to speed up hydrate formation. However, these solid compounds have given contradictory results. This study investigated the effect of high thermal conductive metallic nanofluids of silver (Ag) and copper (Cu) on CH4 and CO2 hydrates. The solid particles were suspended in a 0.03 wt% SDS aqueous solution, and the results were compared with the 0.03 wt% SDS and deionized water samples. A stirred tank batch reactor was used to conduct the thermodynamic and kinetic experiments. The thermodynamic study revealed that 0.1 wt% of solid particles do not shift the equilibrium curve significantly. The kinetic evaluation, including induction time, the initial rate of gas consumption, half-completion time, t50 and semi-completion time, t95, gas uptake, and storage capacity, have been studied. The results show that the Ag and Cu promote CH4 hydrates while they inhibit or do not significantly influence the CO2 hydrates formation. A predictive correlation was introduced to get the apparent rate constant of hydrate formation in the presence of metal-based fluid at the concentrations range of 0.005-0.1 wt%.
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Affiliation(s)
- Omar Nashed
- Department of Chemical Engineering, Faculty of Technical Engineering, Bright Star University, El-Brega 218645, Libya
| | - Behzad Partoon
- Department of Biological and Chemical Engineering, Aarhus University, Universitetsbyen 36, 8000 Aarhus, Denmark
| | - Bhajan Lal
- Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar 32610, Perak, Malaysia
- CO2 Research Centre, Universiti Teknologi PETRONAS, Bandar Seri Iskandar 31750, Perak, Malaysia
| | - Khalik Mohamad Sabil
- PETRONAS Research Sdn Bhd, Kawasan Institusi Bangi, Lot 3288 3289 Off Jalan Ayer Itam, Kajang 43000, Selangor, Malaysia
| | - Sana Yaqub
- U.S. Pakistan Centre for Advance Studies in Energy, Department of Thermal Energy Engineering, National University of Science and Technology, Islamabad 44000, Pakistan
| | - Azmi Mohd Shariff
- Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar 32610, Perak, Malaysia
- CO2 Research Centre, Universiti Teknologi PETRONAS, Bandar Seri Iskandar 31750, Perak, Malaysia
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12
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Frolov SM, Basevich VY, Belyaev AA, Shamshin IO, Aksenov VS, Frolov FS, Storozhenko PA, Guseinov SL. Kinetic Model and Experiment for Self-Ignition of Triethylaluminum and Triethylborane Droplets in Air. Micromachines (Basel) 2022; 13:2033. [PMID: 36422462 PMCID: PMC9695131 DOI: 10.3390/mi13112033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/18/2022] [Accepted: 11/18/2022] [Indexed: 06/16/2023]
Abstract
Triethylaluminum Al(C2H5)3, TEA, and triethylborane, B(C2H5)3, TEB, are transparent, colorless, pyrophoric liquids with boiling points of approximately 190 °C and 95 °C, respectively. Upon contact with ambient air, TEA, TEB, as well as their mixtures and solutions, in hydrocarbon solvents, ignite. They can also violently react with water. TEA and TEB can be used as hypergolic rocket propellants and incendiary compositions. In this manuscript, a novel scheme of the heterogeneous interaction of gaseous oxygen with liquid TEA/TEB microdroplets accompanied by the release of light hydrocarbon radicals into the gas phase is used for calculating the self-ignition of a spatially homogeneous mixture of fuel microdroplets in ambient air at normal pressure and temperature (NPT) conditions. In the primary initiation step, TEA and TEB react with oxygen, producing an ethyl radical, which can initiate an autoxidation chain. The ignition delay is shown to decrease with the decrease in the droplet size. Preliminary experiments on the self-ignition of pulsed and continuous TEA-TEB sprays in ambient air at NPT conditions are used for estimating the Arrhenius parameters of the rate-limiting reaction. Experiments confirm that the self-ignition delay of TEA-TEB sprays decreases with the injection pressure and provide the data for estimating the activation energy of the rate-limiting reaction, which appears to be close to 2 kcal/mol.
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Affiliation(s)
- Sergey M. Frolov
- Department of Combustion and Explosion, Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, 119991 Moscow, Russia
- Institute of Laser and Plasma Technologies, National Research Nuclear University “Moscow Engineering Physics Institute”, 115409 Moscow, Russia
| | - Valentin Y. Basevich
- Department of Combustion and Explosion, Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Andrey A. Belyaev
- Department of Combustion and Explosion, Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Igor O. Shamshin
- Department of Combustion and Explosion, Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Viktor S. Aksenov
- Institute of Laser and Plasma Technologies, National Research Nuclear University “Moscow Engineering Physics Institute”, 115409 Moscow, Russia
| | - Fedor S. Frolov
- Department of Combustion and Explosion, Semenov Federal Research Center for Chemical Physics of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Pavel A. Storozhenko
- State Research Center “State Scientific Research Institute of Chemistry and Technology of Organo-Element Compounds”, 105118 Moscow, Russia
| | - Shirin L. Guseinov
- State Research Center “State Scientific Research Institute of Chemistry and Technology of Organo-Element Compounds”, 105118 Moscow, Russia
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13
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Nabi RAU, Naz MY, Shukrullah S, Ghamkhar M, Rehman NU, Irfan M, Alqarni AO, Legutko S, Kruszelnicka I, Ginter-Kramarczyk D, Ochowiak M, Włodarczak S, Krupińska A, Matuszak M. Analysis of Statistically Predicted Rate Constants for Pyrolysis of High-Density Plastic Using R Software. Materials (Basel) 2022; 15:ma15175910. [PMID: 36079292 PMCID: PMC9457231 DOI: 10.3390/ma15175910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/18/2022] [Accepted: 08/24/2022] [Indexed: 05/30/2023]
Abstract
The surge in plastic waste production has forced researchers to work on practically feasible recovery processes. Pyrolysis is a promising and intriguing option for the recycling of plastic waste. Developing a model that simulates the pyrolysis of high-density polyethylene (HDPE) as the most common polymer is important in determining the impact of operational parameters on system behavior. The type and amount of primary products of pyrolysis, such as oil, gas, and waxes, can be predicted statistically using a multiple linear regression model (MLRM) in R software. To the best of our knowledge, the statistical estimation of kinetic rate constants for pyrolysis of high-density plastic through MLRM analysis using R software has never been reported in the literature. In this study, the temperature-dependent rate constants were fixed experimentally at 420 °C. The rate constants with differences of 0.02, 0.03, and 0.04 from empirically set values were analyzed for pyrolysis of HDPE using MLRM in R software. The added variable plots, scatter plots, and 3D plots demonstrated a good correlation between the dependent and predictor variables. The possible changes in the final products were also analyzed by applying a second-order differential equation solver (SODES) in MATLAB version R2020a. The outcomes of experimentally fixed-rate constants revealed an oil yield of 73% to 74%. The oil yield increased to 78% with a difference of 0.03 from the experimentally fixed rate constants, but light wax, heavy wax, and carbon black decreased. The increased oil and gas yield with reduced byproducts verifies the high significance of the conducted statistical analysis. The statistically predicted kinetic rate constants can be used to enhance the oil yield at an industrial scale.
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Affiliation(s)
- Rao Adeel Un Nabi
- Department of Physics, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Muhammad Yasin Naz
- Department of Physics, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Shazia Shukrullah
- Department of Physics, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Madiha Ghamkhar
- Department of Mathematics and Statistics, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Najeeb Ur Rehman
- Department of Physics, COMSATS University Islamabad, Islamabad 45550, Pakistan
| | - Muhammad Irfan
- Electrical Engineering Department, College of Engineering, Najran University Saudi Arabia, Najran 61441, Saudi Arabia
| | - Ali O. Alqarni
- Department of Pharmaceutical Chemistry, College of Pharmacy, Najran University, Najran 61441, Saudi Arabia
| | - Stanisław Legutko
- Faculty of Mechanical Engineering, Poznan University of Technology, 60-965 Poznan, Poland
| | - Izabela Kruszelnicka
- Faculty of Environmental Engineering and Energy, Department of Water Supply and Bioeconomy, Poznan University of Technology, 60-965 Poznan, Poland
| | - Dobrochna Ginter-Kramarczyk
- Faculty of Environmental Engineering and Energy, Department of Water Supply and Bioeconomy, Poznan University of Technology, 60-965 Poznan, Poland
| | - Marek Ochowiak
- Department of Chemical Engineering and Equipment, Poznan University of Technology, 60-965 Poznan, Poland
| | - Sylwia Włodarczak
- Department of Chemical Engineering and Equipment, Poznan University of Technology, 60-965 Poznan, Poland
| | - Andżelika Krupińska
- Department of Chemical Engineering and Equipment, Poznan University of Technology, 60-965 Poznan, Poland
| | - Magdalena Matuszak
- Department of Chemical Engineering and Equipment, Poznan University of Technology, 60-965 Poznan, Poland
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14
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Reynolds S, Kazan SM, Anton A, Alizadeh T, Gunn RN, Paley MN, Tozer GM, Cunningham VJ. Kinetic modelling of dissolution dynamic nuclear polarisation 13 C magnetic resonance spectroscopy data for analysis of pyruvate delivery and fate in tumours. NMR Biomed 2022; 35:e4650. [PMID: 34841602 DOI: 10.1002/nbm.4650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 09/19/2021] [Accepted: 10/24/2021] [Indexed: 06/13/2023]
Abstract
Dissolution dynamic nuclear polarisation (dDNP) of 13 C-labelled pyruvate in magnetic resonance spectroscopy/imaging (MRS/MRSI) has the potential for monitoring tumour progression and treatment response. Pyruvate delivery, its metabolism to lactate and efflux were investigated in rat P22 sarcomas following simultaneous intravenous administration of hyperpolarised 13 C-labelled pyruvate (13 C1 -pyruvate) and urea (13 C-urea), a nonmetabolised marker. A general mathematical model of pyruvate-lactate exchange, incorporating an arterial input function (AIF), enabled the losses of pyruvate and lactate from tumour to be estimated, in addition to the clearance rate of pyruvate signal from blood into tumour, Kip , and the forward and reverse fractional rate constants for pyruvate-lactate signal exchange, kpl and klp . An analogous model was developed for urea, enabling estimation of urea tumour losses and the blood clearance parameter, Kiu . A spectral fitting procedure to blood time-course data proved superior to assuming a gamma-variate form for the AIFs. Mean arterial blood pressure marginally correlated with clearance rates. Kiu equalled Kip , indicating equivalent permeability of the tumour vasculature to urea and pyruvate. Fractional loss rate constants due to effluxes of pyruvate, lactate and urea from tumour tissue into blood (kpo , klo and kuo , respectively) indicated that T1 s and the average flip angle, θ, obtained from arterial blood were poor surrogates for these parameters in tumour tissue. A precursor-product model, using the tumour pyruvate signal time-course as the input for the corresponding lactate signal time-course, was modified to account for the observed delay between them. The corresponding fractional rate constant, kavail , most likely reflected heterogeneous tumour microcirculation. Loss parameters, estimated from this model with different TRs, provided a lower limit on the estimates of tumour T1 for lactate and urea. The results do not support use of hyperpolarised urea for providing information on the tumour microcirculation over and above what can be obtained from pyruvate alone. The results also highlight the need for rigorous processes controlling signal quantitation, if absolute estimations of biological parameters are required.
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Affiliation(s)
- Steven Reynolds
- Academic Unit of Radiology, Department of Infection, Immunity and Cardiovascular Disease, The Medical School, University of Sheffield, Sheffield, UK
| | - Samira M Kazan
- Department of Oncology and Metabolism, The Medical School, University of Sheffield, Sheffield, UK
| | - Adriana Anton
- Academic Unit of Radiology, Department of Infection, Immunity and Cardiovascular Disease, The Medical School, University of Sheffield, Sheffield, UK
| | - Tooba Alizadeh
- Department of Oncology and Metabolism, The Medical School, University of Sheffield, Sheffield, UK
| | - Roger N Gunn
- Department of Brain Sciences, Imperial College London, London, UK
| | - Martyn N Paley
- Academic Unit of Radiology, Department of Infection, Immunity and Cardiovascular Disease, The Medical School, University of Sheffield, Sheffield, UK
| | - Gillian M Tozer
- Department of Oncology and Metabolism, The Medical School, University of Sheffield, Sheffield, UK
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15
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Wang K, Wang W, Fan C, Li J, Lei T, Zhang W, Shi B, Chen Y, Liu M, Lian C, Wang Z, Ge M. Reactions of C 12-C 14 n-Alkylcyclohexanes with Cl Atoms: Kinetics and Secondary Organic Aerosol Formation. Environ Sci Technol 2022; 56:4859-4870. [PMID: 35319183 DOI: 10.1021/acs.est.1c08958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Long-chain alkanes are a type of intermediate volatility organic compound (IVOC) in the atmosphere and a potential source of secondary organic aerosols (SOAs). C12-C14 n-alkylcyclohexanes are important compositions of IVOCs, with considerable concentrations and emission rates. The reaction rate constants and SOA formation of the reactions of C12-C14 n-alkylcyclohexanes with Cl atoms were investigated in the present study. The reaction rate constants of the long-chain alkanes obtained via the relative-rate method at 298 ± 0.2 K (in units of ×10-10 cm3 molecule-1 s-1) were as follows: khexylcyclohexane = 5.11 ± 0.28, kheptylcyclohexane = 5.56 ± 0.30, and koctylcyclohexane = 5.74 ± 0.31. The gas-phase products of the reactions were identified as mainly small molecules of aldehydes, ketones, and acids. The particle-phase products were mostly monomers and oligomers, but there were still trimers even under high-NOx conditions. Moreover, under high-NOx conditions (urban atmosphere), the SOA yields of hexylcyclohexane are higher than that under low-NOx conditions (remote atmosphere), indicating that more attention should be given to the SOA formation of Cl-initiated n-alkylcyclohexane oxidations in polluted regions. This research can further clarify the oxidation processes and SOA formation of n-alkylcyclohexanes in the atmosphere.
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Affiliation(s)
- Ke Wang
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Weigang Wang
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Cici Fan
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Junling Li
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- Chinese Research Academy of Environmental Sciences, Beijing 100012, P. R. China
| | - Ting Lei
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Wenyu Zhang
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Bo Shi
- Hebei Normal University, Shijiazhuang 050010, P. R. China
| | - Yan Chen
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Mingyuan Liu
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Chaofan Lian
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Zhe Wang
- Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong SAR 999077, P. R. China
| | - Maofa Ge
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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16
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Maršavelski A, Mavri J, Vianello R, Stare J. Why Monoamine Oxidase B Preferably Metabolizes N-Methylhistamine over Histamine: Evidence from the Multiscale Simulation of the Rate-Limiting Step. Int J Mol Sci 2022; 23:1910. [PMID: 35163835 DOI: 10.3390/ijms23031910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 11/18/2022] Open
Abstract
Histamine levels in the human brain are controlled by rather peculiar metabolic pathways. In the first step, histamine is enzymatically methylated at its imidazole Nτ atom, and the produced N-methylhistamine undergoes an oxidative deamination catalyzed by monoamine oxidase B (MAO-B), as is common with other monoaminergic neurotransmitters and neuromodulators of the central nervous system. The fact that histamine requires such a conversion prior to oxidative deamination is intriguing since MAO-B is known to be relatively promiscuous towards monoaminergic substrates; its in-vitro oxidation of N-methylhistamine is about 10 times faster than that for histamine, yet this rather subtle difference appears to be governing the decomposition pathway. This work clarifies the MAO-B selectivity toward histamine and N-methylhistamine by multiscale simulations of the rate-limiting hydride abstraction step for both compounds in the gas phase, in aqueous solution, and in the enzyme, using the established empirical valence bond methodology, assisted by gas-phase density functional theory (DFT) calculations. The computed barriers are in very good agreement with experimental kinetic data, especially for relative trends among systems, thereby reproducing the observed MAO-B selectivity. Simulations clearly demonstrate that solvation effects govern the reactivity, both in aqueous solution as well as in the enzyme although with an opposing effect on the free energy barrier. In the aqueous solution, the transition-state structure involving histamine is better solvated than its methylated analog, leading to a lower barrier for histamine oxidation. In the enzyme, the higher hydrophobicity of N-methylhistamine results in a decreased number of water molecules at the active side, leading to decreased dielectric shielding of the preorganized catalytic electrostatic environment provided by the enzyme. This renders the catalytic environment more efficient for N-methylhistamine, giving rise to a lower barrier relative to histamine. In addition, the transition state involving N-methylhistamine appears to be stabilized by the surrounding nonpolar residues to a larger extent than with unsubstituted histamine, contributing to a lower barrier with the former.
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Monluc L, Nikolayev AA, Medvedkov IA, Azyazov VN, Morozov AN, Mebel AM. The Reaction of o-Benzyne with Vinylacetylene: An Unexplored Way to Produce Naphthalene. Chemphyschem 2021; 23:e202100758. [PMID: 34767677 DOI: 10.1002/cphc.202100758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/12/2021] [Indexed: 11/09/2022]
Abstract
The mechanism and kinetics of the reaction of ortho-benzyne with vinylacetylene have been studied by ab initio and density functional CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G(d,p) calculations of the pertinent potential energy surface combined with Rice-Ramsperger-Kassel-Marcus - Master Equation calculations of reaction rate constants at various temperatures and pressures. Under prevailing combustion conditions, the reaction has been shown to predominantly proceed by the biradical acetylenic mechanism initiated by the addition of C4 H4 to one of the C atoms of the triple bond in ortho-benzyne by the acetylenic end, with a significant contribution of the concerted addition mechanism. Following the initial reaction steps, an extra six-membered ring is produced and the rearrangement of H atoms in this new ring leads to the formation of naphthalene, which can further dissociate to 1- or 2-naphthyl radicals. The o-C6 H4 +C4 H4 reaction is highly exothermic, by ∼143 kcal/mol to form naphthalene and by 31-32 kcal mol-1 to produce naphthyl radicals plus H, but features relatively high entrance barriers of 9-11 kcal mol-1 . Although the reaction is rather slow, much slower than the reaction of phenyl radical with vinylacetylene, it forms naphthalene and 1- and 2-naphthyl radicals directly, with their relative yields controlled by the temperature and pressure, and thus represents a viable source of the naphthalene core under conditions where ortho-benzyne and vinylacetylene are available.
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Affiliation(s)
- Lisa Monluc
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA.,Present address: Department of Chemistry and Biochemistry, Florida State University, 102 Varsity Way, Tallahassee, FI, 32306, USA
| | - Anatoliy A Nikolayev
- Samara National Research University, Samara, 443086, Russia.,Lebedev Physical Institute, Samara, 443011, Russia
| | - Iakov A Medvedkov
- Samara National Research University, Samara, 443086, Russia.,Lebedev Physical Institute, Samara, 443011, Russia
| | - Valeriy N Azyazov
- Samara National Research University, Samara, 443086, Russia.,Lebedev Physical Institute, Samara, 443011, Russia
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida, 33199, USA
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18
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Adachi T, Suzuki Y, Fujisawa T. Photodegradation of an Anilide Fungicide Inpyrfluxam in Water and Nitrate Aqueous Solution. J Agric Food Chem 2021; 69:12966-12973. [PMID: 34699205 DOI: 10.1021/acs.jafc.1c03813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The photodegradation behavior of a new anilide fungicide, inpyrfluxam [3-difluoromethyl-N-[(R)-2,3-dihydro-1,1,3-trimethyl-1H-inden-4-yl]-1-methylpyrazole-4-carboxamide] (1), was investigated in aqueous buffer and nitrate solutions under irradiation with artificial sunlight (λ > 290 nm). In both media, 1 mainly photodegraded via oxidation at the 3'-position of the Indane ring, cleavage of the C-N bond of the amide linkage and N-phenyl ring bond, and finally mineralization to carbon dioxide. No isomerization of 1 occurred at the 3'-position of the Indane ring. In the presence of nitrate ion, which originates from fertilizer in agricultural fields, the degradation of 1 was significantly accelerated as compared with buffer solution, and the reaction rate was strongly correlated with the concentration of hydroxyl radicals derived from the photolysis of nitrate ions. The reaction rate constant of hydroxyl radicals with 1 was determined to be 3.0 × 1010 /M/s, which was higher than that of hydroxyl radicals with other pesticides possessing aromatic rings.
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Affiliation(s)
- Takeshi Adachi
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 4-2-1 Takatsukasa, Takarazuka, Hyogo 665-8555, Japan
| | - Yusuke Suzuki
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 4-2-1 Takatsukasa, Takarazuka, Hyogo 665-8555, Japan
| | - Takuo Fujisawa
- Environmental Health Science Laboratory, Sumitomo Chemical Co., Ltd., 4-2-1 Takatsukasa, Takarazuka, Hyogo 665-8555, Japan
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19
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Silverman AI, Boehm AB. Systematic Review and Meta-Analysis of the Persistence of Enveloped Viruses in Environmental Waters and Wastewater in the Absence of Disinfectants. Environ Sci Technol 2021; 55:14480-14493. [PMID: 34665598 DOI: 10.1021/acs.est.1c03977] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Enveloped viruses are characterized by a lipid-containing envelope that encapsulates the virion, and they have been the cause of major outbreaks and pandemics. Some enveloped viruses are excreted in feces and other bodily fluids of infected people and animals, raising the question of their fate in the aquatic environment. Consequently, we conducted a systematic review and meta-analysis of the decay rate constants (k) of enveloped viruses from 12 families (i.e., Coronaviridae, Cystoviridae (specifically Phi6), Filoviridae, Hepadnaviridae, Herpesviridae, Orthomyxoviridae, Paramyxoviridae, Pneumoviridae, Poxviridae, Retroviridae, Rhabdoviridae, Togaviridae) in environmental waters and wastewater to evaluate their decay kinetics and identify the environmental and virus characteristics that influence k. A total of 812 k that met inclusion criteria were identified in the literature, with the number of k for each family ranging from 0 to 560, and the virus family averaged values of k ranging from 0.11 d-1 and 1.85 d-1. Virus type (i.e., genus, species, subspecies, or subtype), method of virus enumeration (i.e., culture-based or (RT-)QPCR), and experimental water matrix type, temperature and sterility were found to have significant effects on k. Additionally, enveloped viruses were found to have statistically significantly greater k than nonenveloped viruses. Multiple linear regression models that allow prediction of log10k as a function of virus type, enumeration method, water temperature, and water type are provided for six virus families that had sufficient data available for model fitting (i.e., Coronaviridae, Phi6, Herpesviridae, Orthomyxoviridae, Rhabdoviridae, Togaviridae). Compiled log10k and multiple regression models can be used to inform management of human and animal waste, operation of water and wastewater facilities, and exposure risks to treatment plant workers and communities living in regions that lack treatment facilities. Given limited data available for some enveloped virus families with a potential water-related transmission route, there is need for additional data collection to aid academic researchers, public health agencies, and water and wastewater professionals involved in outbreak response.
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Affiliation(s)
- Andrea I Silverman
- Department of Civil and Urban Engineering, New York University Tandon School of Engineering, Brooklyn, New York 11201, United States
| | - Alexandria B Boehm
- Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States
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20
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Osik NA, Zelentsova EA, Tsentalovich YP. Kinetic Studies of Antioxidant Properties of Ovothiol A. Antioxidants (Basel) 2021; 10:antiox10091470. [PMID: 34573105 PMCID: PMC8470380 DOI: 10.3390/antiox10091470] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 02/01/2023] Open
Abstract
Ovothiol A (OSH) is one of the strongest natural antioxidants. So far, its presence was found in tissues of marine invertebrates, algae and fish. Due to very low pKa value of the SH group, under physiological conditions, this compound is almost entirely present in chemically active thiolate form and reacts with ROS and radicals significantly faster than other natural thiols. In biological systems, OSH acts in tandem with glutathione GSH, with OSH neutralizing oxidants and GSH maintaining ovothiol in the reduced state. In the present work, we report the rate constants of OSH oxidation by H2O2 and of reduction of oxidized ovothiol OSSO by GSH and we estimate the Arrhenius parameters for these rate constants. The absorption spectra of reaction intermediates, adduct OSSG and sulfenic acid OSOH, were obtained. We also found that OSH effectively quenches the triplet state of kynurenic acid with an almost diffusion-controlled rate constant. This finding indicates that OSH may serve as a good photoprotector to inhibit the deleterious effect of solar UV irradiation; this assumption explains the high concentrations of OSH in the fish lens. The unique antioxidant and photoprotecting properties of OSH open promising perspectives for its use in the treatment of human diseases.
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Affiliation(s)
- Nataliya A. Osik
- International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia; (N.A.O.); (E.A.Z.)
- Physical Department, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Ekaterina A. Zelentsova
- International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia; (N.A.O.); (E.A.Z.)
- Physical Department, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
| | - Yuri P. Tsentalovich
- International Tomography Center SB RAS, Institutskaya 3a, 630090 Novosibirsk, Russia; (N.A.O.); (E.A.Z.)
- Physical Department, Novosibirsk State University, Pirogova 2, 630090 Novosibirsk, Russia
- Correspondence:
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21
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Lattouf E, Anttalainen O, Kotiaho T, Hakulinen H, Vanninen P, Eiceman G. Parametric Sensitivity in a Generalized Model for Atmospheric Pressure Chemical Ionization Reactions. J Am Soc Mass Spectrom 2021; 32:2218-2226. [PMID: 34264074 DOI: 10.1021/jasms.1c00158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Gas phase reactions between hydrated protons H+(H2O)n and a substance M, as seen in atmospheric pressure chemical ionization (APCI) with mass spectrometry (MS) and ion mobility spectrometry (IMS), were modeled computationally using initial amounts of [M] and [H+(H2O)n], rate constants k1 to form protonated monomer (MH+(H2O)x) and k2 to form proton bound dimer (M2H+(H2O)z), and diffusion constants. At 1 × 1010 cm-3 (0.4 ppb) for [H+(H2O)n] and vapor concentrations for M from 10 ppb to 10 ppm, a maximum signal was reached at 4.5 μs to 4.6 ms for MH+(H2O)x and 7.8 μs to 46 ms for M2H+(H2O)z. Maximum yield for protonated monomer for a reaction time of 1 ms was ∼40% for k1 from 10-11 to 10-8 cm3·s-1, for k2/k1 = 0.8, and specific values of [M]. This model demonstrates that ion distributions could be shifted from [M2H+(H2O)z] to [MH+(H2O)x] using excessive levels of [H+(H2O)n], even for [M] > 10 ppb, as commonly found in APCI MS and IMS measurements. Ion losses by collisions on surfaces were insignificant with losses of <0.5% for protonated monomer and <0.1% for proton bound dimer of dimethyl methylphosphonate (DMMP) at 5 ms. In this model, ion production in an APCI environment is treated over ranges of parameters important in mass spectrometric measurements. The models establish a foundation for detailed computations on response with mixtures of neutral substances.
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Affiliation(s)
- Elie Lattouf
- VERIFIN, Finnish Institute for Verification of the Chemical Weapons Convention, Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Osmo Anttalainen
- VERIFIN, Finnish Institute for Verification of the Chemical Weapons Convention, Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Tapio Kotiaho
- Drug Research Program and Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland
- Department of Chemistry, Faculty of Science, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
| | - Hanna Hakulinen
- VERIFIN, Finnish Institute for Verification of the Chemical Weapons Convention, Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Paula Vanninen
- VERIFIN, Finnish Institute for Verification of the Chemical Weapons Convention, Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
| | - Gary Eiceman
- VERIFIN, Finnish Institute for Verification of the Chemical Weapons Convention, Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland
- Department of Chemistry and Biochemistry, New Mexico State University, 1175 N Horseshoe Drive, Las Cruces, New Mexico 88003, United States
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22
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Carre-Burritt AE, Van Hoomissen DJ, Vyas S. Role of pH in the Transformation of Perfluoroalkyl Carboxylic Acids by Activated Persulfate: Implications from the Determination of Absolute Electron-Transfer Rates and Chemical Computations. Environ Sci Technol 2021; 55:8928-8936. [PMID: 34170127 DOI: 10.1021/acs.est.1c02389] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Perfluoroalkyl carboxylic acids (PFCAs) are ubiquitous contaminants known for their bioaccumulation, toxicological harm, and resistance to degradation. Remediating PFCAs in water is an ongoing challenge with existing technologies being insufficient or requiring additional disposal. An emergent approach is using activated persulfate, which degrades PFCAs through sequential scission of CF2 equivalents yielding shorter-chain homologues, CO2 and F-. This transformation is thought to be initiated by single electron transfer (SET) from the PFCA to the activate oxidant, SO4•-. A pronounced pH effect has been observed for thermally activated persulfate PFCA transformation. To evaluate the role of pH during SET, we directly determined absolute rate constants for perfluorobutanoic acid and trifluoroacetic acid oxidation by SO4•- in the pH range of 0.5-4.0 using laser flash photolysis. The average of the rate constants for both substrates across all pH values was 9 ± 2 × 103 M-1 s-1 (±2σ), implying that acid catalysis of thermal persulfate activation may be the primary culprit of the observed pH effect, instead of pH influencing the SET step. In addition, density functional theory was used to investigate if SO4•-protonation might enhance PFCA transformation kinetics. We found that when calculations include explicit water molecules, direct SO4•- protonation does not occur.
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Affiliation(s)
- Asa E Carre-Burritt
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Daniel J Van Hoomissen
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Shubham Vyas
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
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23
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Filatov VV, Nikiforov SM, Zelenov VV, Pento AV, Bukharina AB, Sulimenkov IV, Brusov VS, Yu J, Kozlovskiy VI. Ionization of organic molecules with metal ions formed in the laser plasma. J Mass Spectrom 2021; 56:e4723. [PMID: 33813767 DOI: 10.1002/jms.4723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 12/09/2020] [Accepted: 03/10/2021] [Indexed: 06/12/2023]
Abstract
A laser plasma ion source was used to ionize volatile organic compounds in a gas sample. The plasma was generated on a metal target in the intermediate vacuum region of ~0.3 Torr using a pulsed Nd:YAG laser with a wavelength of 1 μm. The resulting ions mass spectra were acquired using orthogonal time-of-flight mass spectrometer (O-TOF MS). When using a copper target, the ions formed are simple complexes (CuM+ ) of copper ions with organic molecules. The possibility of online identification of trace amounts of alkanes in nitrogen and air, with a detection limit of ~10 ppb, was demonstrated. The ionization efficiency of volatile organic compounds through the formation of clusters with metal ions is 10-4 in terms of the quasimolecular complex ions. The rate constants of ion-molecular reactions of copper ions with octane and water molecules in nitrogen and air are estimated.
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Affiliation(s)
- Vasily V Filatov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432, Russia
| | | | - Vladislav V Zelenov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432, Russia
| | - Andrey V Pento
- Prokhorov General Physics Institute, RAS, Moscow, 119991, Russia
| | | | - Ilia V Sulimenkov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432, Russia
| | - Vladimir S Brusov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432, Russia
| | - Jiajun Yu
- Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou, 510632, China
| | - Viacheslav I Kozlovskiy
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432, Russia
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24
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Saira F, Saleemi S, Razzaq H, Qureshi R. Spectrophotometric analysis of stability of gold nanoparticles during catalytic reduction of 4-nitrophenol. Turk J Chem 2021; 45:82-91. [PMID: 33679155 PMCID: PMC7925321 DOI: 10.3906/kim-2004-52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 10/13/2020] [Indexed: 11/25/2022] Open
Abstract
Spectrophotometric monitoring of 4-nitrophenol (4-NP) reduction by sodium borohydride (NaBH4) using gold nanoparticles (GNPs) as a catalyst has been extensively studied, but the stability of GNPs in terms of change in the surface plasmon resonance (SPR) at different temperatures has not been explored. In the present investigation, our aim was to evaluate the SPR stability of GNPs as a catalyst during the reduction of 4-NP at different elevated temperatures (i.e. 30–60 °C) and sodium borohydride concentrations. Sensitivity of this degradation process toward concentration of GNPs at a range of temperatures is also evaluated. The spectrophotometric results reveal that up to 45 °C, 12 ± 1.5 nm catalyst has a consistent optical density (OD) during the entire 4-NP reduction process, which is related to the surface integrity of catalyst atoms. As the temperature approached 50 °C, the OD gradually decreased and showed a blue shift as the reaction proceeded, which could be related to a decrease in particle size or surface dissolution of gold atoms. The present study may find application in the design of catalysts for the reduction of organic pollutants in industrial wastewater at a range of temperatures.
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Affiliation(s)
- Farhat Saira
- Nanoscience and Technical Division, National Centre for Physics (NCP), Islamabad Pakistan
| | - Samia Saleemi
- Department of Chemistry, Quaid-i-Azam University, Islamabad Pakistan
| | - Humaira Razzaq
- Department of Chemistry, University of Wah, Rawalpindi Pakistan
| | - Rumana Qureshi
- Department of Chemistry, Quaid-i-Azam University, Islamabad Pakistan
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25
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Sadygov RG. High-Resolution Mass Spectrometry for In Vivo Proteome Dynamics using Heavy Water Metabolic Labeling. Int J Mol Sci 2020; 21:E7821. [PMID: 33105654 DOI: 10.3390/ijms21217821] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 02/07/2023] Open
Abstract
Cellular proteins are continuously degraded and synthesized. The turnover of proteins is essential to many cellular functions. Combined with metabolic labeling using stable isotopes, LC-MS estimates proteome dynamics in high-throughput and on a large scale. Modern mass spectrometers allow a range of instrumental settings to optimize experimental output for specific research goals. One such setting which affects the results for dynamic proteome studies is the mass resolution. The resolution is vital for distinguishing target species from co-eluting contaminants with close mass-to-charge ratios. However, for estimations of proteome dynamics from metabolic labeling with stable isotopes, the spectral accuracy is highly important. Studies examining the effects of increased mass resolutions (in modern mass spectrometers) on the proteome turnover output and accuracy have been lacking. Here, we use a publicly available heavy water labeling and mass spectral data sets of murine serum proteome (acquired on Orbitrap Fusion and Agilent 6530 QToF) to analyze the effect of mass resolution of the Orbitrap mass analyzer on the proteome dynamics estimation. Increased mass resolution affected the spectral accuracy and the number acquired tandem mass spectra.
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26
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Behmand B, Noronha AM, Wilds CJ, Marignier JL, Mostafavi M, Wagner JR, Hunting DJ, Sanche L. Hydrated electrons induce the formation of interstrand cross-links in DNA modified by cisplatin adducts. J Radiat Res 2020; 61:343-351. [PMID: 32211848 PMCID: PMC7299263 DOI: 10.1093/jrr/rraa014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/17/2020] [Indexed: 06/10/2023]
Abstract
Double-stranded oligonucleotides containing cisplatin adducts, with and without a mismatched region, were exposed to hydrated electrons generated by gamma-rays. Gel electrophoresis analysis demonstrates the formation of cisplatin-interstrand crosslinks from the cisplatin-intrastrand species. The rate constant per base for the reaction between hydrated electrons and the double-stranded oligonucleotides with and without cisplatin containing a mismatched region was determined by pulse radiolysis to be 7 × 109 and 2 × 109 M-1 s-1, respectively. These results provide a better understanding of the radiosensitizing effect of cisplatin adducts in hypoxic tumors and of the formation of interstrand crosslinks, which are difficult for cells to repair.
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Affiliation(s)
- B Behmand
- Groupe en sciences des radiations, Faculté de médicine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada
| | - A M Noronha
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec, H4B1R6, Canada
| | - C J Wilds
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec, H4B1R6, Canada
| | - J-L Marignier
- Centre de cinétique rapide ELYSE, Laboratoire de chimie physique, Université de Paris-Saclay 11, Orsay, France
| | - M Mostafavi
- Centre de cinétique rapide ELYSE, Laboratoire de chimie physique, Université de Paris-Saclay 11, Orsay, France
| | - J R Wagner
- Groupe en sciences des radiations, Faculté de médicine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada
| | - D J Hunting
- Groupe en sciences des radiations, Faculté de médicine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada
| | - L Sanche
- Groupe en sciences des radiations, Faculté de médicine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, J1H 5N4, Canada
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27
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Schex R, Schweiggert F, Wüstenberg B, Bonrath W, Schäfer C, Schweiggert R. Kinetic and Thermodynamic Study of the Thermally Induced ( E/Z)-Isomerization of the retro-Carotenoid Rhodoxanthin. J Agric Food Chem 2020; 68:5259-5269. [PMID: 32314916 DOI: 10.1021/acs.jafc.0c00933] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The hitherto scarcely investigated retro-carotenoid rhodoxanthin possesses high potential for coloration in the food and beverage industry using technofunctional formulations prepared thereof. Hence, we studied (E/Z)-isomerization pathways of rhodoxanthin, including seven (E/Z)-isomers comprising (Z)-configured double bonds at unusual exocyclic and inner polyene chain positions. A mathematical approach was developed to deduce kinetic and thermodynamic parameters of six parallel equilibrium reactions interconnecting (all-E)-rhodoxanthin with mono-, di-, and tri-(Z)-isomers using multiresponse modeling. At 40-70 °C in ethyl acetate, reaction rate constants regarding the rotation from (all-E)- to (6Z)-rhodoxanthin were 11-14 times higher than those of the common (E/Z)-isomerization reaction at C-13,14 of the non-retro-structured carotenoid canthaxanthin. Moreover, the equilibrium reaction between (all-E)- and (6Z)-rhodoxanthin was strongly product favored as indicated by negative Gibbs energies (-1.6 to -2.2 kJ mol-1), which is unusual for carotenoids within the studied temperatures. Overall, this study provides novel insights into structure-related dependencies of (E/Z)-isomerization reaction kinetics and thermodynamics of polyenes.
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Affiliation(s)
- Roland Schex
- Research and Development Center Forms, DSM Nutritional Products, P.O. Box 2676, 4002 Basel, Switzerland
- Institute of Beverage Research, Analysis and Technology of Plant-Based Foods, Geisenheim University, Von-Lade-Strasse 1, 65366 Geisenheim, Germany
| | - Franz Schweiggert
- Institute for Applied Information Processing, University of Ulm, Helmholtzstrasse 18, 89081 Ulm, Germany
| | - Bettina Wüstenberg
- Research and Development Center Chemistry, DSM Nutritional Products, P.O. Box 2676, 4002 Basel, Switzerland
| | - Werner Bonrath
- Research and Development Center Chemistry, DSM Nutritional Products, P.O. Box 2676, 4002 Basel, Switzerland
| | - Christian Schäfer
- Research and Development Center Forms, DSM Nutritional Products, P.O. Box 2676, 4002 Basel, Switzerland
| | - Ralf Schweiggert
- Institute of Beverage Research, Analysis and Technology of Plant-Based Foods, Geisenheim University, Von-Lade-Strasse 1, 65366 Geisenheim, Germany
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28
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Dome K, Podgorbunskikh E, Bychkov A, Lomovsky O. Changes in the Crystallinity Degree of Starch Having Different Types of Crystal Structure after Mechanical Pretreatment. Polymers (Basel) 2020; 12:E641. [PMID: 32178224 PMCID: PMC7183072 DOI: 10.3390/polym12030641] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/06/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023] Open
Abstract
This paper examines the effect of mechanical activation on the amorphization of starch having different types of crystalline structure (A-type corn starch; B-type potato starch; and C-type tapioca starch). Structural properties of the starches were studied by X-ray diffraction analysis. Mechanical activation in a planetary ball mill reduces the degree of crystallinity in proportion to pretreatment duration. C-type tapioca starch was found to have the highest degree of crystallinity. Energy consumed to achieve complete amorphization of the starches having different types of crystalline structure was measured. The kinetic parameters of the process (the effective rate constants) were determined. The rate constant and the strongest decline in the crystallinity degree after mechanical activation change in the following series: C-type starch, A-type starch, and B-type starch.
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Affiliation(s)
- Karina Dome
- Department of Natural Sciences, Novosibirsk State University, Pirogov Str. 1, Novosibirsk 630090, Russia;
- Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences, Kutateladze Str. 18, Novosibirsk 630128, Russia; (E.P.); (O.L.)
| | - Ekaterina Podgorbunskikh
- Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences, Kutateladze Str. 18, Novosibirsk 630128, Russia; (E.P.); (O.L.)
| | - Aleksey Bychkov
- Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences, Kutateladze Str. 18, Novosibirsk 630128, Russia; (E.P.); (O.L.)
- Department of business, Novosibirsk State Technical University, K. Marks Ave. 20, Novosibirsk 630073, Russia
| | - Oleg Lomovsky
- Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch, Russian Academy of Sciences, Kutateladze Str. 18, Novosibirsk 630128, Russia; (E.P.); (O.L.)
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29
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Zhang L, Truhlar DG, Sun S. Association of Cl with C 2H 2 by unified variable-reaction-coordinate and reaction-path variational transition-state theory. Proc Natl Acad Sci U S A 2020; 117:5610-6. [PMID: 32123079 DOI: 10.1073/pnas.1920018117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Barrierless unimolecular association reactions are prominent in atmospheric and combustion mechanisms but are challenging for both experiment and kinetics theory. A key datum for understanding the pressure dependence of association and dissociation reactions is the high-pressure limit, but this is often available experimentally only by extrapolation. Here we calculate the high-pressure limit for the addition of a chlorine atom to acetylene molecule (Cl + C2H2→C2H2Cl). This reaction has outer and inner transition states in series; the outer transition state is barrierless, and it is necessary to use different theoretical frameworks to treat the two kinds of transition state. Here we study the reaction in the high-pressure limit using multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) at the outer transition state and reaction-path variational transition state theory (RP-VTST) at the inner turning point; then we combine the results with the canonical unified statistical (CUS) theory. The calculations are based on a density functional validated against the W3X-L method, which is based on coupled cluster theory with single, double, and triple excitations and a quasiperturbative treatment of connected quadruple excitations [CCSDT(Q)], and the computed rate constants are in good agreement with some of the experimental results. The chlorovinyl (C2H2Cl) adduct has two isomers that are equilibrium structures of a double-well C≡C-H bending potential. Two procedures are used to calculate the vibrational partition function of chlorovinyl; one treats the two isomers separately and the other solves the anharmonic energy levels of the double well. We use these results to calculate the standard-state free energy and equilibrium constant of the reaction.
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30
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Eun C. Effects of the Size, the Number, and the Spatial Arrangement of Reactive Patches on a Sphere on Diffusion-limited Reaction Kinetics: A Comprehensive Study. Int J Mol Sci 2020; 21:ijms21030997. [PMID: 32028667 PMCID: PMC7037656 DOI: 10.3390/ijms21030997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 01/31/2020] [Indexed: 11/17/2022] Open
Abstract
We investigate how the size, the number, and the spatial arrangement of identical nonoverlapping reactive patches on a sphere influence the overall reaction kinetics of bimolecular diffusion-limited (or diffusion-controlled) reactions that occur between the patches and the reactants diffusing around the sphere. First, in the arrangement of two patches, it is known that the overall rate constant increases as the two patches become more separated from each other but decreases when they become closer to each other. In this work, we further study the dependence of the patch arrangement on the kinetics with three and four patches using the finite element method (FEM). In addition to the patch arrangement, the kinetics is also dependent on the number and size of the patches. Therefore, we study such dependences by calculating the overall rate constants using the FEM for various cases, especially for large-sized patches, and this study is complementary to the kinetic studies that were performed by Brownian dynamics (BD) simulation methods for small-sized patches. The numerical FEM and BD simulation results are compared with the results from various kinetic theories to evaluate the accuracies of the theories. Remarkably, this comparison indicates that our theory, which was recently developed based on the curvature-dependent kinetic theory, shows good agreement with the FEM and BD numerical results. From this validation, we use our theory to further study the variation of the overall rate constant when the patches are arbitrarily arranged on a sphere. Our theory also confirms that to maximize the overall rate constant, we need to break large-sized patches into smaller-sized patches and arrange them to be maximally separated to reduce their competition.
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Affiliation(s)
- Changsun Eun
- Department of Chemistry, Hankuk University of Foreign Studies, Yongin 17035, Korea
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31
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Kusio J, Sitkowska K, Konopko A, Litwinienko G. Hydroxycinnamyl Derived BODIPY as a Lipophilic Fluorescence Probe for Peroxyl Radicals. Antioxidants (Basel) 2020; 9:antiox9010088. [PMID: 31968662 PMCID: PMC7022944 DOI: 10.3390/antiox9010088] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 01/21/2023] Open
Abstract
Herein, we describe the synthesis of a fluorescent probe NB-2 and its use for the detection of peroxyl radicals. This probe is composed of two receptor segments (4-hydroxycinnamyl moieties) sensitive towards peroxyl radicals that are conjugated with a fluorescent reporter, dipyrrometheneboron difluoride (BODIPY), whose emission changes depend on the oxidation state of the receptors. The measurement of the rate of peroxidation of methyl linoleate in a micellar system in the presence of 1.0 µM NB-2 confirmed its ability to trap lipid peroxyl radicals with the rate constant kinh = 1000 M−1·s−1, which is ten-fold smaller than for pentamethylchromanol (an analog of α-tocopherol). The reaction of NB-2 with peroxyl radicals was further studied via fluorescence measurements in methanol, with α,α′-azobisisobutyronitrile (AIBN) used as a source of radicals generated by photolysis or thermolysis, and in the micellar system at pH 7.4, with 2,2′-azobis(2-amidinopropane) (ABAP) used as a thermal source of the radicals. The reaction of NB-2 receptors with peroxyl radicals manifests itself by the strong increase of a fluorescence with a maximum at 612–616 nm, with a 14-fold enhancement of emission in methanol and a 4-fold enhancement in the micelles, as compared to the unoxidized probe. Our preliminary results indicate that NB-2 behaves as a “switch on” fluorescent probe that is suitable for sensing peroxyl radicals in an organic lipid environment and in bi-phasic dispersed lipid systems.
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Affiliation(s)
- Jaroslaw Kusio
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (J.K.); (A.K.)
| | - Kaja Sitkowska
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (J.K.); (A.K.)
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Correspondence: (K.S.); (G.L.)
| | - Adrian Konopko
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (J.K.); (A.K.)
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093 Warsaw, Poland
| | - Grzegorz Litwinienko
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (J.K.); (A.K.)
- Correspondence: (K.S.); (G.L.)
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Abstract
Traditionally, the thermodynamic values of affinity are considered as the main criterion for the development of new drugs. Usually, these values for drugs are measured <i>in vitro</i> at steady concentrations of the receptor and ligand, which are differed from <i>in vivo</i> environment. Recent studies have shown that the kinetics of the process of drug binding to its receptor make significant contribution in the drug effectiveness. This has increased attention in characterizing and predicting the rate constants of association and dissociation of the receptor ligand at the stage of preclinical studies of drug candidates. A drug with a long residence time can determine ligand-receptor selectivity (kinetic selectivity), maintain pharmacological activity of the drug at its low concentration in vivo. The paper discusses the theoretical basis of protein-ligand binding, molecular determinants that control the kinetics of the drug-receptor binding. Understanding the molecular features underlying the kinetics of receptor-ligand binding will contribute to the rational design of drugs with desired properties.
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Affiliation(s)
- D V Borisov
- Institute of Biomedical Chemistry, Moscow, Russia
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33
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Konopko A, Kusio J, Litwinienko G. Antioxidant Activity of Metal Nanoparticles Coated with Tocopherol-Like Residues-The Importance of Studies in Homo- and Heterogeneous Systems. Antioxidants (Basel) 2019; 9:E5. [PMID: 31861581 PMCID: PMC7022694 DOI: 10.3390/antiox9010005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/16/2019] [Accepted: 12/17/2019] [Indexed: 01/10/2023] Open
Abstract
Functionalized nanoparticles (NPs) attract great attention in pharmacy, diagnostics, and biomedical areas due to benefits like localization and unique interactions of NPs with biocomponents of living cells. In the present paper, we prepared and characterized two kinds of gold nanoparticles (AuNPs) coated with α-tocopherol-like residues: 1A were soluble in non-polar solvents and their antioxidant activity was tested during the peroxidation of a model hydrocarbon in a homogeneous system, whereas nanoparticles 1B were soluble in polar solvents and were applied as antioxidants in micellar and liposomal systems. The effectiveness of 1A is comparable to 2,2,5,7,8-pentamethylchroman-6-ol (PMHC, an analogue of α-tocopherol). Taking the results of the kinetic measurements, we calculated an average number of 2150 chromanol residues per one NP, suggesting a thick organic coating around the metal core. In heterogeneous systems, the peroxidation of methyl linoleate dispersed in Triton X-100 micelles or DMPC liposomes resulted in the observation that 1B (545 chromanol residues per one NP) was active enough to effectively inhibit peroxidation in a micellar system, but in a liposomal system, 1B behaved as a retardant (no clear induction period). The importance of microenvironment in heterogeneous systems on the overall antioxidant activity of nanoparticles is discussed.
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Affiliation(s)
- Adrian Konopko
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (A.K.); (J.K.)
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093 Warsaw, Poland
| | - Jaroslaw Kusio
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (A.K.); (J.K.)
| | - Grzegorz Litwinienko
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland; (A.K.); (J.K.)
- Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warsaw, Poland
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34
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Li X, Gao Y, Zuo C, Zheng S, Xu F, Sun Y, Zhang Q. The Gas-Phase Formation Mechanism of Dibenzofuran (DBF), Dibenzothiophene (DBT), and Carbazole (CA) from Benzofuran (BF), Benzothiophene (BT), and Indole (IN) with Cyclopentadienyl Radical. Int J Mol Sci 2019; 20:E5420. [PMID: 31683506 PMCID: PMC6861977 DOI: 10.3390/ijms20215420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 10/28/2019] [Accepted: 10/28/2019] [Indexed: 11/16/2022] Open
Abstract
Benzofuran (BF), benzothiophene (BT), indole (IN), dibenzofuran (DBF), dibenzothiophene (DBT), and carbazole (CA) are typical heterocyclic aromatic compounds (NSO-HETs), which can coexist with polycyclic aromatic hydrocarbons (PAHs) in combustion and pyrolysis conditions. In this work, quantum chemical calculations were carried out to investigate the formation of DBF, DBT, and CA from the reactions of BF, BT, and IN with a cyclopentadienyl radical (CPDyl) by using the hybrid density functional theory (DFT) at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. The rate constants of crucial elementary steps were deduced over 600-1200 K, using canonical variational transition state theory with a small-curvature tunneling contribution (CVT/SCT). This paper showed that the production of DBF, DBT, and CA from the reactions of BF, BT, and IN with CPDyl involved six elementary steps: the addition reaction, ring closure, the first H shift, C-C cleavage, the second H shift, and elimination of CH3 or H. The cleavage of the C-C bond was regarded as the rate-determining step for each pathway due to the extremely high barrier. The 1-methyl substituted products were more easily formed than the 4-methyl substituted products. The main products were DBF and 1-methyl-DBF, DBT and 1-methyl-DBT, and CA and 1-methyl-CA for reactions of BF, BT, and IN with CPDyl, respectively. The ranking of DBF, DBT, and CA formation potential was as follows: DBT and methyl-DBT formation > DBF and methyl-DBF formation > CA, and methyl-CA formation. Comparison with the reaction of naphthalene with CPDyl indicated that the reactions of CPDyl attacking a benzene ring and a furan/thiophene/pyrrole ring could be inferred to be comparable under high temperature conditions.
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Affiliation(s)
- Xuan Li
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Yixiang Gao
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Chenpeng Zuo
- Environment Research Institute, Shandong University, Qingdao 266237, China.
- Shenzhen Research Institute, Shandong University, Shenzhen 518057, China.
| | - Siyuan Zheng
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Fei Xu
- Environment Research Institute, Shandong University, Qingdao 266237, China.
- Shenzhen Research Institute, Shandong University, Shenzhen 518057, China.
| | - Yanhui Sun
- College of Environment and Safety Engineering, Qingdao University of Science & Technology, Qingdao 266042, China.
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
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Chen X, Sun Y, Qi Y, Liu L, Xu F, Zhao Y. Mechanistic and Kinetic Investigations on the Ozonolysis of Biomass Burning Products: Guaiacol, Syringol and Creosol. Int J Mol Sci 2019; 20:E4492. [PMID: 31514377 DOI: 10.3390/ijms20184492] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 08/26/2019] [Accepted: 09/07/2019] [Indexed: 02/01/2023] Open
Abstract
The lignin pyrolysis products generated by biomass combustion make an essential contribution to the formation of secondary organic aerosols (SOAs). The ozone-initiated oxidation of guaiacol, syringol and creosol, major constituents of biomass burning, were investigated theoretically by using the density functional theory (DFT) method at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level. Six primary addition reaction pathways and further decomposition routes with corresponding thermodynamic values were proposed. The Criegee intermediates can be excited by small molecules, such as NOx, H2O in the atmosphere, and would further proceed via self-decomposition or isomerization. The most predominant product for ozonation of guaiacol is the monomethyl muconate (P1). At 295 K and atmospheric pressure, the rate constant is 1.10 × 10-19 cm3 molecule-1 s-1, which is lies a factor of 4 smaller than the previous experimental study. The branching ratios of the six channels are calculated based on corresponding rate coefficient. The present work mainly provides a more comprehensive and detailed theoretical research on the ozonation of methoxyphenol, which aspires to offer novel insights and reference for future experimental and theoretical work and control techniques of SOAs caused by lignin pyrolysis products.
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Liavitskaya T, Vyazovkin S. All You Need to Know about the Kinetics of Thermally Stimulated Reactions Occurring on Cooling. Molecules 2019; 24:E1918. [PMID: 31109036 DOI: 10.3390/molecules24101918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 11/16/2022] Open
Abstract
In this tutorial overview article the authors share their original experience in studying the kinetics of thermally stimulated reactions under the conditions of continuous cooling. It is stressed that the kinetics measured on heating is similar to that measured on cooling only for single-step reactions. For multi-step reactions the respective kinetics can differ dramatically. The application of an isoconversional method to thermogravimetry (TGA) or differential scanning calorimetry (DSC) data allows one to recognize multi-step kinetics in the form of the activation energy that varies with conversion. Authors' argument is supported by theoretical considerations as well as by experimental examples that include the reactions of thermal decomposition and crosslinking polymerization (curing). The observed differences in the kinetics measured on heating and cooling ultimately manifest themselves in the Arrhenius plots of the opposite curvatures, which means that the heating kinetics cannot be used to predict the kinetics on cooling. The article provides important background knowledge necessary for conducting successful kinetic studies on cooling. It includes a practical advice on optimizing the parameters of cooling experiments as well as on proper usage of kinetic methods for analysis of obtained data.
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Zuo C, Wang H, Pan W, Zheng S, Xu F, Zhang Q. Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors. Int J Mol Sci 2019; 20:E1542. [PMID: 30934774 DOI: 10.3390/ijms20071542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/16/2019] [Accepted: 03/22/2019] [Indexed: 12/31/2022] Open
Abstract
Polychlorinated phenoxathiins (PCPTs), polychlorinated dibenzothiophenes (PCDTs), and polychlorinated thianthrenes (PCTAs) are sulfur analogues of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/DFs). Chlorothiophenols (CTPs) and chlorophenols (CPs) are key precursors for the formation of PCTA/PT/DTs, which can react with H or OH to form chloro(thio)phenoxy radical, sulfydryl/hydroxyl-substituted phenyl radicals, and (thio)phenoxyl diradicals. However, previous radical/radical PCTA/DT formation mechanisms in the literature failed to explain the higher concentration of PCDTs than that of PCTAs under the pyrolysis or combustion conditions. In this work, a detailed thermodynamics and kinetic calculations were carried out to investigate the pre-intermediate formation for PCTA/PT/DTs from radical/molecule coupling of the 2-C(T)P with their key radical species. Our study showed that the radical/molecule coupling mechanism explains the gas-phase formation of PCTA/PT/DTs in both thermodynamic and kinetic perspectives. The S/C coupling modes to form thioether-(thio)enol intermediates are preferable over the O/C coupling modes to form ether-(thio)enol intermediates. Thus, although the radical/molecule coupling of chlorophenoxy radical with 2-C(T)P has no effect on the PCDD/PT formation, the radical/molecule coupling of chlorothiophenoxy radical with 2-C(T)P plays an important role in the PCTA/PT formation. Most importantly, the pre-PCDT intermediates formation pathways from the couplings of sulfydryl/hydroxyl-substituted phenyl radical with 2-C(T)P and (thio)phenoxyl diradicals with 2-C(T)P are more favorable than pre-PCTA/PT intermediates formation pathways from the coupling of chlorothiophenoxy radical with 2-C(T)P, which provides reasonable explanation for the high PCDT-to-PCTA ratio in the environment.
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Huang YJ, Cao G, Zhu RS, Ouyang F. [Heterogeneous Oxidation of Secondary Organic Tracers of Isoprene and Toluene by Ozone]. Huan Jing Ke Xue 2019; 40:1163-1171. [PMID: 31087962 DOI: 10.13227/j.hjkx.201803064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
For this paper, chamber experiments were carried out to investigate the oxidation of secondary organic tracers of toluene and isoprene by ozone under different conditions (relative humidity, mixing state, etc.) using a relative rate constants approach. The uncertainty of the tracer-based method due to the ozone oxidation of secondary organic tracers was also addressed. The results showed that the effective rate constants of analogue of 2-methyl erythritol (AME) and 2,3-dihydroxy-4-oxopentanoic acid (DHOPA) were (4.60±0.66)×10-19 cm3·(molecule·s)-1and (6.57±0.51)×10-19 cm3·(molecule·s)-1, respectively. Given the instability of the secondary organic tracers caused by the oxidation, the contributions of toluene and isoprene to secondary organic aerosols could be underestimated by 16.5%-44.8% and 18.3%-47.3%, respectively.
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Affiliation(s)
- Ya-Juan Huang
- Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Gang Cao
- Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Rong-Shu Zhu
- Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China
| | - Feng Ouyang
- Shenzhen Key Laboratory of Organic Pollution Prevention and Control, School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen 518055, China
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Baschieri A, Amorati R, Benelli T, Mazzocchetti L, D'Angelo E, Valgimigli L. Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes. Antioxidants (Basel) 2019; 8:E30. [PMID: 30691231 PMCID: PMC6406349 DOI: 10.3390/antiox8020030] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 01/21/2019] [Accepted: 01/24/2019] [Indexed: 12/31/2022] Open
Abstract
Antioxidant activity of native vitamin C (ascorbic acid, AH₂) is hampered by instability in solution. Selective loading of AH₂ into the inner lumen of natural halloysite nanotubes (HNT) yields a composite nanoantioxidant (HNT/AH₂), which was characterized and investigated for its reactivity with the persistent 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical and with transient peroxyl radicals in the inhibited autoxidation of organic substrates, both in organic solution (acetonitrile) and in buffered (pH 7.4) water in comparison with native AH₂. HNT/AH₂ showed excellent antioxidant performance being more effective than native ascorbic acid by 131% in acetonitrile and 290% (three-fold) in aqueous solution, under identical settings. Reaction with peroxyl radicals has a rate constant of 1.4 × 10⁶ M-1 s-1 and 5.1 × 10⁴ M-1 s-1, respectively, in buffered water (pH 7.4) and acetonitrile, at 30 °C. Results offer physical understanding of the factors governing HNT/AH₂ reactivity. Improved performance of HNT/AH₂ is unprecedented among forms of stabilized ascorbic acid and its relevance is discussed on kinetic grounds.
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Affiliation(s)
- Andrea Baschieri
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy.
| | - Riccardo Amorati
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy.
| | - Tiziana Benelli
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
| | - Laura Mazzocchetti
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
| | - Emanuele D'Angelo
- Department of Industrial Chemistry "Toso Montanari", University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.
| | - Luca Valgimigli
- Department of Chemistry "G. Ciamician", University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy.
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40
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Thankappan R, Srinivasan SV, Suthanthararajan R, Sillanpää M. Studies on removal of phenol sulfonic acid-syntan in aqueous medium using ozonation. Environ Technol 2018; 39:2434-2446. [PMID: 28707563 DOI: 10.1080/09593330.2017.1355936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
The removal of phenol sulfonic acid-syntan (PSAS) in terms of chemical oxygen demand (COD) was studied at different pH, ozone and initial PSAS concentrations and the optimum condition was found to be pH 7, ozone concentration of 5.2 × 10-3 mmol/L and initial PSAS concentration of 500 mg/L. The increase in BOD5/COD ratio confirmed the bio-treatability of ozonated PSAS effluent. The excitation-emission matrix intensity and Fourier transmission infra-red spectroscopy confirmed the generation of intermediate by-product during degradation of PSAS. The ozonation of PSAS was found to obey fast regime pseudo-first-order reaction with a rate constant of 3.7 × 10-9 mol-1 s-1. The mean oxidation state of carbon value between +2 and +3 confirmed that the ozonation of PSAS resulted in partial mineralization.
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Affiliation(s)
- Rema Thankappan
- a Environmental Technology Division , Central Leather Research Institute , Adyar , India
| | - S V Srinivasan
- a Environmental Technology Division , Central Leather Research Institute , Adyar , India
| | - R Suthanthararajan
- a Environmental Technology Division , Central Leather Research Institute , Adyar , India
| | - Mika Sillanpää
- b Laboratory of Green Chemistry , Lappenranta University of Technology , Mikkeli , Finland
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41
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Willberger C, Amayri S, Reich T. Determination of kinetic parameters of redox reactions using CE-ICP-MS: A case study for the reduction of Np(V) by hydroxylamine hydrochloride. Electrophoresis 2018; 39:3013-3021. [PMID: 30192411 DOI: 10.1002/elps.201800318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/30/2018] [Accepted: 08/30/2018] [Indexed: 11/10/2022]
Abstract
The rate constants k of the reduction of 5 × 10-5 M Np(V) to Np(IV) by hydroxylamine hydrochloride (HAHCl) in 1 M HCl have been determined by CE-ICP-MS in the temperature range of ϑ = 30-70°C and with varying concentrations of HAHCl from 1 to 7.2 M. The reaction was found to have (pseudo)first order kinetics with respect to HAHCl. The experimental results for k ranged from 0.0029(1) min-1 (ϑ = 40°C, c(HAHCl) = 3 M) to 0.039(7) min-1 (ϑ = 60°C, c(HAHCl) = 7.2 M). The activation energy of the reaction was determined as EA = (72 ± 10) kJ/mol. These results and a comparison with literature data show that the coupling of CE to ICP-MS provides a powerful analytical tool for the investigation of the kinetic aspects of redox reactions of actinides at low concentrations. On the basis of this proof-of-principle study, the method presented here can be extended to the investigation of the kinetic parameters of other redox systems containing different actinides (or transition metals) and oxidants/reductants.
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Affiliation(s)
- Christian Willberger
- Institut für Kernchemie, Fritz-Strassmann-Weg 2, Johannes Gutenberg-Universität, Mainz, Germany
| | - Samer Amayri
- Institut für Kernchemie, Fritz-Strassmann-Weg 2, Johannes Gutenberg-Universität, Mainz, Germany
| | - Tobias Reich
- Institut für Kernchemie, Fritz-Strassmann-Weg 2, Johannes Gutenberg-Universität, Mainz, Germany
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42
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Ivanov Y, Kozlov AF, Galiullin RA, Tatur VY, Ziborov VS, Ivanova ND, Pleshakova TO, Vesnin SG, Goryanin I. Use of Microwave Radiometry to Monitor Thermal Denaturation of Albumin. Front Physiol 2018; 9:956. [PMID: 30090068 PMCID: PMC6068392 DOI: 10.3389/fphys.2018.00956] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 06/29/2018] [Indexed: 11/25/2022] Open
Abstract
This study monitored thermal denaturation of albumin using microwave radiometry. Brightness Temperature, derived from Microwave Emission (BTME) of an aqueous solution of bovine serum albumin (0.1 mM) was monitored in the microwave frequency range 3.8–4.2 GHz during denaturation of this protein at a temperature of 56°C in a conical polypropylene cuvette. This method does not require fluorescent or radioactive labels. A microwave emission change of 1.5–2°C in the BTME of aqueous albumin solution was found during its denaturation, without a corresponding change in the water temperature. Radio thermometry makes it possible to monitor protein denaturation kinetics, and the resulting rate constant for albumin denaturation was 0.2 ± 0.1 min−1, which corresponds well to rate constants obtained by other methods.
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Affiliation(s)
- Yuri Ivanov
- Institute of Biomedical Chemistry, Moscow, Russia
| | | | | | - Vadim Y Tatur
- Foundation of Advanced Technologies and Innovations, Moscow, Russia
| | - Vadim S Ziborov
- Joint Institute for High Temperatures of Russian Academy of Sciences (RAS), Moscow, Russia
| | - Nina D Ivanova
- Moscow State Academy of Veterinary Medicine and Biotechnology, Moscow, Russia
| | | | - Sergey G Vesnin
- RES LTD, Moscow, Russia.,Medical MicroWave Radiometry (MMWR) LTD, Edinburgh, United Kingdom
| | - Igor Goryanin
- School of Informatics, University of Edinburgh, Edinburgh, United Kingdom.,Biological Systems Unit, Okinawa Institute of Science and Technology, Okinawa, Japan.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
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43
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Shan X, Clary DC. Application of one-dimensional semiclassical transition state theory to the CH 3OH + H ⇌ CH 2OH/CH 3O + H 2 reactions. Philos Trans A Math Phys Eng Sci 2018; 376:rsta.2017.0147. [PMID: 29431675 PMCID: PMC5805916 DOI: 10.1098/rsta.2017.0147] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/31/2017] [Indexed: 05/12/2023]
Abstract
The rate constants of the two branches of H-abstractions from CH3OH by the H-atom and the corresponding reactions in the reverse direction are calculated using the one-dimensional semiclassical transition state theory (1D SCTST). In this method, only the reaction mode vibration of the transition state (TS) is treated anharmonically, while the remaining internal degrees of freedom are treated as they would have been in a standard TS theory calculation. A total of eight ab initio single-point energy calculations are performed in addition to the computational cost of a standard TS theory calculation. This allows a second-order Richardson extrapolation method to be employed to improve the numerical estimation of the third- and fourth-order derivatives, which in turn are used in the calculation of the anharmonic constant. Hindered-rotor (HR) vibrations are identified in the equilibrium states of CH3OH and CH2OH, and the TSs of the reactions. The partition function of the HRs are calculated using both a simple harmonic oscillator model and a more sophisticated one-dimensional torsional eigenvalue summation (1D TES) method. The 1D TES method can be easily adapted in 1D SCTST computation. The resulting 1D SCTST with 1D TES rate constants show good agreement to previous theoretical and experimental works. The effects of the HR on rate constants for different reactions are also investigated.This article is part of the theme issue 'Modern theoretical chemistry'.
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Affiliation(s)
- Xiao Shan
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - David C Clary
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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Jelliffe R, Bayard D. New Perspectives in Clinical Pharmacokinetics-1: the Importance of Updating the Teaching in Pharmacokinetics that both Clearance and Elimination Rate Constant Approaches Are Mathematically Proven Equally Valid. AAPS J 2018; 20:36. [PMID: 29484513 DOI: 10.1208/s12248-018-0185-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 01/04/2018] [Indexed: 11/30/2022]
Abstract
The healing professions have only about four main therapeutic tools at their disposal-surgery, drugs, physical therapy, and psychotherapy. For the general profession of internal medicine, drug therapy is its primary tool. Providing an understanding of the state-of-the-art in therapeutic methods, grounded in solid scientific and mathematical rigor, is therefore of the utmost clinical importance for both physicians and clinical pharmacists. This is particularly true where rapidly evolving scientific changes require an up-to-date education upon which students can rely. Unfortunately, relatively little attention has been paid to training clinical pharmacokineticists and physicians to manage drug therapy optimally for patients under their care in their everyday practice. In this paper, we discuss one of these basic deficiencies from the perspective of the longstanding controversy in pharmacokinetic modeling: whether the volume and clearance approach or the volume and rate constant approach is somehow "better". We examine this controversy using the mathematical principle of invariance, which to our knowledge has not been done before. The conclusion of this analysis is that both approaches are rigorously proven mathematically to be equally valid. We also discuss some implications of these equally valid approaches from the framework of mechanistic and non-compartmental models. Ultimately, the conclusion is that the choice of one parameterization over the other is based on preference or usefulness for research or clinical practice, but no longer, because of this analysis, on science.
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Affiliation(s)
- Roger Jelliffe
- USC Laboratory of Applied Pharmacokinetics and Bioinformatics, University of Southern California School of Medicine, Children's Hospital of Los Angeles, 4650 Sunset Boulevard, #51, Los Angeles, CA, 90027, USA.
| | - David Bayard
- USC Laboratory of Applied Pharmacokinetics and Bioinformatics, University of Southern California School of Medicine, Children's Hospital of Los Angeles, 4650 Sunset Boulevard, #51, Los Angeles, CA, 90027, USA
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45
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Ebrahimzadeh R, Ghazanfari Moghaddam A, Sarcheshmehpour M, Mortezapour H. A novel kinetic modeling method for the stabilization phase of the composting process for biodegradation of solid wastes. Waste Manag Res 2017; 35:1226-1236. [PMID: 29113577 DOI: 10.1177/0734242x17733538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Biomass degradation kinetics of the composting process for kitchen waste, pruned elm tree branches and sheep manure were studied to model changes in volatile solids (VS) over time. Three experimental reactors containing raw mixtures with a carbon to nitrogen (C/N) ratio of 27:1 and a moisture content of 65% were prepared. During the composting process two of the reactors used forced air and the third used natural aeration. The composting stabilization phases in all reactors were completed in 30 days. During this period, composting indexes such as temperature, moisture content and VS changes were recorded. Elementary reactions were used for kinetics modeling of the degradation process. Results showed that the numerical values of rate constant ( k) for zero-order ranged from 0.86 to 1.03 VS×day-1, for first-order models it ranged from 0.01 to 0.02 day-1, for second-order the range was from 1.36×10-5 to 1.78×10-5 VS-1×day-1 and for n-order the rate constant ranged from 0.031 to 0.095 VS(1-n)×day-1. The resulting models were validated by comparing statistical parameters. Evaluation of the models showed that, in the aerated reactors, the n-order models (less than 1) successfully estimated the VS changes. In the non-aeration reactor, for the second-order model good agreement was achieved between the simulated and actual quantities of VS. Also, half-life time provided a useful criterion for the estimation of expected time for completion of different phases of composting.
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Affiliation(s)
- Reza Ebrahimzadeh
- 1 Department of Mechanics of Biosystem Engineering,Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
- 2 Young Researchers' Society, Shahid Bahonar University of Kerman,Kerman, Iran
| | - Ahmad Ghazanfari Moghaddam
- 1 Department of Mechanics of Biosystem Engineering,Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Mehdi Sarcheshmehpour
- 3 Department of Science of Soil Engineering, Faculty of Agriculture, Shahid Bahonar University of Kerman,Kerman, Iran
| | - Hamid Mortezapour
- 1 Department of Mechanics of Biosystem Engineering,Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
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Abstract
SIGNIFICANCE Glutathione metabolism is comparable to a jigsaw puzzle with too many pieces. It is supposed to comprise (i) the reduction of disulfides, hydroperoxides, sulfenic acids, and nitrosothiols, (ii) the detoxification of aldehydes, xenobiotics, and heavy metals, and (iii) the synthesis of eicosanoids, steroids, and iron-sulfur clusters. In addition, glutathione affects oxidative protein folding and redox signaling. Here, I try to provide an overview on the relevance of glutathione-dependent pathways with an emphasis on quantitative data. Recent Advances: Intracellular redox measurements reveal that the cytosol, the nucleus, and mitochondria contain very little glutathione disulfide and that oxidative challenges are rapidly counterbalanced. Genetic approaches suggest that iron metabolism is the centerpiece of the glutathione puzzle in yeast. Furthermore, recent biochemical studies provide novel insights on glutathione transport processes and uncoupling mechanisms. CRITICAL ISSUES Which parts of the glutathione puzzle are most relevant? Does this explain the high intracellular concentrations of reduced glutathione? How can iron-sulfur cluster biogenesis, oxidative protein folding, or redox signaling occur at high glutathione concentrations? Answers to these questions not only seem to depend on the organism, cell type, and subcellular compartment but also on different ideologies among researchers. FUTURE DIRECTIONS A rational approach to compare the relevance of glutathione-dependent pathways is to combine genetic and quantitative kinetic data. However, there are still many missing pieces and too little is known about the compartment-specific repertoire and concentration of numerous metabolites, substrates, enzymes, and transporters as well as rate constants and enzyme kinetic patterns. Gathering this information might require the development of novel tools but is crucial to address potential kinetic competitions and to decipher uncoupling mechanisms to solve the glutathione puzzle. Antioxid. Redox Signal. 27, 1130-1161.
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Affiliation(s)
- Marcel Deponte
- Department of Parasitology, Ruprecht-Karls University , Heidelberg, Germany
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Pangannaya S, Purayil NP, Dabhi S, Mankad V, Jha PK, Shinde S, Trivedi DR. Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications. Beilstein J Org Chem 2017; 13:222-238. [PMID: 28326131 PMCID: PMC5331291 DOI: 10.3762/bjoc.13.25] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 01/18/2017] [Indexed: 12/29/2022] Open
Abstract
New colorimetric receptors R1 and R2 with varied positional substitution of a cyano and nitro signaling unit having a hydroxy functionality as the hydrogen bond donor site have been designed, synthesized and characterized by FTIR, 1H NMR spectroscopy and mass spectrometry. The receptors R1 and R2 exhibit prominent visual response for F− and AcO– ions allowing the real time analysis of these ions in aqueous media. The formation of the receptor–anion complexes has been supported by UV–vis titration studies and confirmed through binding constant calculations. The anion binding process follows a first order rate equation and the calculated rate constants reveal a higher order of reactivity for AcO− ions. The 1H NMR titration and TDDFT studies provide full support of the binding mechanism. The Hg2+ and F− ion sensing property of receptor R1 has been utilized to arrive at “AND” and “INHIBIT” molecular logic gate applications.
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Affiliation(s)
- Srikala Pangannaya
- Supramolecular Chemistry Laboratory, Department of Chemistry, National Institute of Technology Karnataka (NITK), Surathkal, India
| | - Neethu Padinchare Purayil
- Supramolecular Chemistry Laboratory, Department of Chemistry, National Institute of Technology Karnataka (NITK), Surathkal, India
| | - Shweta Dabhi
- Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364001, India
| | - Venu Mankad
- Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364001, India
| | - Prafulla K Jha
- Department of Physics, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, India
| | - Satyam Shinde
- School of Technology, Pandit Deendayal Petroleum University, Gandhinagar 382007, Gujarat, India
| | - Darshak R Trivedi
- Supramolecular Chemistry Laboratory, Department of Chemistry, National Institute of Technology Karnataka (NITK), Surathkal, India
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Hiratsuka T, Tanaka H, Miyahara MT. Mechanism of Kinetically Controlled Capillary Condensation in Nanopores: A Combined Experimental and Monte Carlo Approach. ACS Nano 2017; 11:269-276. [PMID: 28001354 DOI: 10.1021/acsnano.6b05550] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We find the rule of capillary condensation from the metastable state in nanoscale pores based on the transition state theory. The conventional thermodynamic theories cannot achieve it because the metastable capillary condensation inherently includes an activated process. We thus compute argon adsorption isotherms on cylindrical pore models and atomistic silica pore models mimicking the MCM-41 materials by the grand canonical Monte Carlo and the gauge cell Monte Carlo methods and evaluate the rate constant for the capillary condensation by the transition state theory. The results reveal that the rate drastically increases with a small increase in the chemical potential of the system, and the metastable capillary condensation occurs for any mesopores when the rate constant reaches a universal critical value. Furthermore, a careful comparison between experimental adsorption isotherms and the simulated ones on the atomistic silica pore models reveals that the rate constant of the real system also has a universal value. With this finding, we can successfully estimate the experimental capillary condensation pressure over a wide range of temperatures and pore sizes by simply applying the critical rate constant.
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Affiliation(s)
- Tatsumasa Hiratsuka
- Department of Chemical Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 606-8501, Japan
| | - Hideki Tanaka
- Department of Chemical Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 606-8501, Japan
| | - Minoru T Miyahara
- Department of Chemical Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 606-8501, Japan
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Pan LY, Salas-Solano O, Valliere-Douglass JF. Localized conformational interrogation of antibody and antibody-drug conjugates by site-specific carboxyl group footprinting. MAbs 2016; 9:307-318. [PMID: 27929747 DOI: 10.1080/19420862.2016.1268306] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Establishing and maintaining conformational integrity of monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) during development and manufacturing is critical for ensuring their clinical efficacy. As presented here, we applied site-specific carboxyl group footprinting (CGF) for localized conformational interrogation of mAbs. The approach relies on covalent labeling that introduces glycine ethyl ester tags onto solvent-accessible side chains of protein carboxylates. Peptide mapping is used to monitor the labeling kinetics of carboxyl residues and the labeling kinetics reflects the conformation or solvent-accessibility of side chains. Our results for two case studies are shown here. The first study was aimed at defining the conformational changes of mAbs induced by deglycosylation. We found that two residues in CH2 domain (D268 and E297) show significantly enhanced side chain accessibility upon deglycosylation. This site-specific result highlighted the advantage of monitoring the labeling kinetics at the amino acid level as opposed to the peptide level, which would result in averaging out of highly localized conformational differences. The second study was designed to assess conformational effects brought on by conjugation of mAbs with drug-linkers. All 59 monitored carboxyl residues displayed similar solvent-accessibility between the ADC and mAb under native conditions, which suggests the ADC and mAb share similar side chain conformation. The findings are well correlated and complementary with results from other assays. This work illustrated that site-specific CGF is capable of pinpointing local conformational changes in mAbs or ADCs that might arise during development and manufacturing. The methodology can be readily implemented within the industry to provide comprehensive conformational assessment of these molecules.
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Roy-Mayhew JD, Pope MA, Punckt C, Aksay IA. Intrinsic Catalytic Activity of Graphene Defects for the Co(II/III)(bpy)3 Dye-Sensitized Solar Cell Redox Mediator. ACS Appl Mater Interfaces 2016; 8:9134-9141. [PMID: 26999648 DOI: 10.1021/acsami.6b00937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate that functionalized graphene, rich with lattice defects but lean with oxygen sites, catalyzes the reduction of Co(III)(bpy)3 as well as platinum does, exhibiting a rate of heterogeneous electron transfer, k0, of ∼6 × 10(-3) cm/s. We show this rate to be an order of magnitude higher than on oxygen-site-rich graphene oxide, and over 2 orders of magnitude higher than on the basal plane of graphite (as a surrogate for pristine graphene). Furthermore, dye-sensitized solar cells using defect-rich graphene monolayers perform similarly to those using platinum nanoparticles as the catalyst.
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Affiliation(s)
- Joseph D Roy-Mayhew
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
| | - Michael A Pope
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
- Vorbeck Princeton Research Center, Vorbeck Materials Corporation , 11 Deerpark Drive, Suite 203, Monmouth Junction, New Jersey 08852, United States
| | - Christian Punckt
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
- Vorbeck Princeton Research Center, Vorbeck Materials Corporation , 11 Deerpark Drive, Suite 203, Monmouth Junction, New Jersey 08852, United States
| | - Ilhan A Aksay
- Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States
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