1
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Chernysheva D, Konstantinov M, Sidash E, Baranova T, Klushin V, Tokarev D, Andreeva V, Kolesnikov E, Kaichev V, Gorshenkov M, Smirnova N. Fomes fomentarius as a Bio-Template for Heteroatom-Doped Carbon Fibers for Symmetrical Supercapacitors. Symmetry (Basel) 2023. [DOI: 10.3390/sym15040846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
Abstract
Nowadays, commercial electric double-layer supercapacitors mainly use porous activated carbons due to their high specific surface area, electrical conductivity, and chemical stability. A feature of carbon materials is the possibility of obtaining them from renewable plant biomass. In this study, fungi (Fomes fomentarius) were used as a bio-template for the preparation of carbon fibers via a combination of thermochemical conversion approaches, including a general hydrothermal pre-carbonization step, as well as subsequent carbonization, physical, or chemical activation. The relationships between the preparation conditions and the structural and electrochemical properties of the obtained carbon materials were determined using SEM, TEM, EDAX, XPS, cyclic voltammetry, galvanostatic measurements, and EIS. It was shown that hydrothermal pretreatment in the presence of phosphoric acid ensured the complete removal of inorganic impurities of raw fungus hyphae, but at the same time, saved some heteroatoms, such as O, N, and P. Chemical activation using H3PO4 increased the amount of phosphorus in the carbon material and saved the natural fungus’s structure. The combination of a hierarchical pore structure with O, N, and P heteroatom doping made it possible to achieve good electrochemical properties (specific capacitance values of 220 F/g) and excellent stability after 25,000 charge/discharge cycles in a three-electrode cell. The electrochemical performance in both three- and two-electrode cells exceeded or was comparable to other biomass-derived porous carbons, making it a prospective candidate as an electrode material in symmetrical supercapacitors.
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Affiliation(s)
- Daria Chernysheva
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Maksim Konstantinov
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Ekaterina Sidash
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Tatiana Baranova
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Victor Klushin
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Denis Tokarev
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Veronica Andreeva
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
| | - Evgeny Kolesnikov
- Department of Functional Nanosystems and High-Temperature Materials, National University of Science and Technology MISiS, 119049 Moscow, Russia
| | - Vasily Kaichev
- Department of Catalysis Research, Boreskov Institute of Catalysis, 630090 Novosibirsk, Russia
| | - Mikhail Gorshenkov
- Department of Functional Nanosystems and High-Temperature Materials, National University of Science and Technology MISiS, 119049 Moscow, Russia
| | - Nina Smirnova
- Research Institute “Nanotechnologies and new materials”, Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia
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Molodtsova T, Gorshenkov M, Kubrin S, Saraev A, Ulyankina A, Smirnova N. One-step access to bifunctional γ-Fe2O3/δ-FeOOH electrocatalyst for oxygen reduction reaction and acetaminophen sensing. J Taiwan Inst Chem Eng 2022. [DOI: 10.1016/j.jtice.2022.104569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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3
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Kramar A, Anishchenko V, Kuzema P, Smirnova N, Laguta I, Stavinskaya O, Ivannikov R, Linnik O. Features of lignosulfonate depolymerization and photocatalytic transformation to low-molecular-weight compounds over nano-sized semiconductive films. Appl Nanosci 2022. [DOI: 10.1007/s13204-022-02492-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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4
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Molodtsova T, Gorshenkov M, Saliev A, Vanyushin V, Goncharov I, Smirnova N. One-step synthesis of γ-Fe2O3/Fe3O4 nanocomposite for sensitive electrochemical detection of hydrogen peroxide. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.137723] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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5
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Chernysheva D, Pudova L, Popov Y, Smirnova N, Maslova O, Allix M, Rakhmatullin A, Leontyev N, Nikolaev A, Leontyev I. Non-Isothermal Decomposition as Efficient and Simple Synthesis Method of NiO/C Nanoparticles for Asymmetric Supercapacitors. Nanomaterials (Basel) 2021; 11:nano11010187. [PMID: 33450986 PMCID: PMC7828437 DOI: 10.3390/nano11010187] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/24/2020] [Accepted: 12/27/2020] [Indexed: 11/20/2022]
Abstract
A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. NiO/C nanocomposites are composed of spherical particles distributed over the carbon support surface. The average diameter of nickel oxide spheres increases with the NiO content and are estimated as 36, 50 and 205 nm for nanocomposites with 10, 50 and 80 wt% NiO concentrations, respectively. In turn, each NiO sphere contains several nickel oxide nanoparticles, whose average sizes are 7–8 nm. According to the tests performed using a three-electrode cell, specific capacitance (SC) of NiO/C nanocomposites increases from 200 to 400 F/g as the NiO content achieves a maximum of 60 wt% concentration, after which the SC decreases. The study of the NiO/C composite showing the highest SC in three- and two-electrode cells reveals that its SC remains almost unchanged while increasing the current density, and the sample demonstrates excellent cycling stability properties. Finally, NiO/C (60% NiO) composites are shown to be promising materials for charging quartz clocks with a power rating of 1.5 V (30 min).
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Affiliation(s)
- Daria Chernysheva
- Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia; (D.C.); (L.P.); (N.S.)
| | - Ludmila Pudova
- Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia; (D.C.); (L.P.); (N.S.)
| | - Yuri Popov
- Physics Department, Southern Federal University, 344090 Rostov-on-Don, Russia;
| | - Nina Smirnova
- Platov South-Russian State Polytechnic University (NPI), 346428 Novocherkassk, Russia; (D.C.); (L.P.); (N.S.)
| | - Olga Maslova
- Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, 346428 Tomsk, Russia;
| | - Mathieu Allix
- CNRS, CEMHTI UPR3079, Univ. Orléans, F-45071 Orléans, France; (M.A.); (A.R.)
| | - Aydar Rakhmatullin
- CNRS, CEMHTI UPR3079, Univ. Orléans, F-45071 Orléans, France; (M.A.); (A.R.)
| | - Nikolay Leontyev
- Azov-Black Sea Engineering Institute, Don State Agrarian University, Rostov region, 347740 Zernograd, Russia;
| | - Andrey Nikolaev
- Research and Education Center “Materials”, Don State Technical University, 344000 Rostov-on-Don, Russia;
| | - Igor Leontyev
- Physics Department, Southern Federal University, 344090 Rostov-on-Don, Russia;
- Correspondence: ; Tel.: +7-918-552-4024
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Dubchenko E, Ivanov A, Spirina N, Smirnova N, Melnikov M, Boyko A, Gusev E, Kubatiev A. Hyperhomocysteinemia and Endothelial Dysfunction in Multiple Sclerosis. Brain Sci 2020; 10:brainsci10090637. [PMID: 32947812 PMCID: PMC7564574 DOI: 10.3390/brainsci10090637] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [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: 08/08/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/24/2022] Open
Abstract
Endothelial dysfunction is recognized as one of the leading factors in the pathogenesis of diseases of the central nervous system of various etiologies. Numerous studies have shown the role of hyperhomocysteinemia in the development of endothelial dysfunction and the prothrombogenic state. The most important condition in the development of multiple sclerosis (MS) is a dysregulation of the blood-brain barrier (BBB) and transendothelial leukocyte migration. It has been proven that homocysteine also contributes to the damage of neurons by the mechanism of excitotoxicity and the induction of the apoptosis of neurons. These processes can be one of the factors of neurodegenerative brain damage, which plays a leading role in the progression of MS. This review describes the pleiotropic effect of homocysteine on these processes and its role in MS pathogenesis.
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Affiliation(s)
- Ekaterina Dubchenko
- Department of Neuroimmunology of Federal Center of Brain and Neurotechnology of the Federal Medical-Biological Agency of Russia, 117997 Moscow, Russia; (E.D.); (N.S.); (A.B.)
- Interdistrict Department of Multiple Sclerosis at the State Clinical Hospital VV Veresaeva, 127644 Moscow, Russia
| | - Alexander Ivanov
- Federal State Budgetary Scientific Institution “Institute of General Pathology and Pathophysiology”, 125315 Moscow, Russia; (A.I.); (A.K.)
| | - Natalia Spirina
- Department of Nervous Diseases with Medical Genetics and Neurosurgery Yaroslavl State Medical University, 150000 Yaroslavl, Russia;
| | - Nina Smirnova
- Department of Neuroimmunology of Federal Center of Brain and Neurotechnology of the Federal Medical-Biological Agency of Russia, 117997 Moscow, Russia; (E.D.); (N.S.); (A.B.)
- Department of Neurology, Neurosurgery and Medical Genetic of Pirogov Russian National Research Medical University, 117997 Moscow, Russia;
| | - Mikhail Melnikov
- Department of Neuroimmunology of Federal Center of Brain and Neurotechnology of the Federal Medical-Biological Agency of Russia, 117997 Moscow, Russia; (E.D.); (N.S.); (A.B.)
- Department of Neurology, Neurosurgery and Medical Genetic of Pirogov Russian National Research Medical University, 117997 Moscow, Russia;
- Laboratory of Clinical Immunology, National Research Center Institute of Immunology of the Federal Medical-Biological Agency of Russia, 115478 Moscow, Russia
- Correspondence: ; Tel.: +7-926-331-8946
| | - Alexey Boyko
- Department of Neuroimmunology of Federal Center of Brain and Neurotechnology of the Federal Medical-Biological Agency of Russia, 117997 Moscow, Russia; (E.D.); (N.S.); (A.B.)
- Department of Neurology, Neurosurgery and Medical Genetic of Pirogov Russian National Research Medical University, 117997 Moscow, Russia;
| | - Evgeniy Gusev
- Department of Neurology, Neurosurgery and Medical Genetic of Pirogov Russian National Research Medical University, 117997 Moscow, Russia;
| | - Aslan Kubatiev
- Federal State Budgetary Scientific Institution “Institute of General Pathology and Pathophysiology”, 125315 Moscow, Russia; (A.I.); (A.K.)
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Anisimov E, Faddeev N, Smirnova N. Data on the thermo-fluid simulation of open-cathode fuel cell stack depending on the location of the oxidizer/cooling supply system. Data Brief 2020; 31:105771. [PMID: 32529014 PMCID: PMC7280773 DOI: 10.1016/j.dib.2020.105771] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/27/2020] [Accepted: 05/19/2020] [Indexed: 11/26/2022] Open
Abstract
The content of this paper provides simulation data of the distribution of temperature fields, and oxidizer/cooling agent (air) flows in dependence with location of the oxidizer/cooling supply system in open-cathode polymer electrolyte membrane fuel cell (PEMFC) stack. The finite element method in Solid Works Simulation and Solid Works Flow Simulation software were used for bipolar plate strength calculation and thermo-fluid simulation of PEMFC stack with forced-air convection. The simulations were carried out for two variants of the oxidizer/cooling supply system location - at the entrance to the fuel cell stack (air injection) and at the outlet of the fuel cell stack (air intake).
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Affiliation(s)
- Evgeny Anisimov
- Platov South-Russian State Polytechnic University (NPI), 132 Prosveschenia Str., Novocherkassk 346428 (Russia)
| | - Nikita Faddeev
- Platov South-Russian State Polytechnic University (NPI), 132 Prosveschenia Str., Novocherkassk 346428 (Russia)
| | - Nina Smirnova
- Platov South-Russian State Polytechnic University (NPI), 132 Prosveschenia Str., Novocherkassk 346428 (Russia)
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Morrone C, Rehm S, Smirnova N, Doryab A, Schmid O, Eickelberg O, Yildirim A, Jenne D. Regulation of Cysteine-Protease Activity Prevents Graft Dysfunction during Ischemia-Lung Reperfusion. J Heart Lung Transplant 2020. [DOI: 10.1016/j.healun.2020.01.423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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9
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Linnik O, Popescu-Pelin G, Stefan N, Chorna N, Smirnova N, Mihailescu CN, Ristoscu C, Mihailescu IN. Investigation of nitrogen and iron co-doped TiO2 films synthesized in N2/CH4 via pulsed laser deposition technique. Appl Nanosci 2020. [DOI: 10.1007/s13204-020-01309-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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10
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Mukha I, Khodko A, Vityuk N, Severynovska O, Pivovarenko V, Kachalova N, Smirnova N, Eremenko A. Light-driven formation of gold/tryptophan nanoparticles. Appl Nanosci 2019. [DOI: 10.1007/s13204-019-01171-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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11
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Petrik I, Frolova E, Turchin A, Smirnova N, Eremenko A. Design of titania porous films controlled by precursors’ viscosity for photocatalytic application. Res Chem Intermed 2019. [DOI: 10.1007/s11164-019-03894-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Makenov M, Karan L, Shashina N, Akhmetshina M, Zhurenkova O, Kholodilov I, Karganova G, Smirnova N, Grigoreva Y, Yankovskaya Y, Fyodorova M. First detection of tick-borne encephalitis virus in Ixodes ricinus ticks and their rodent hosts in Moscow, Russia. Ticks Tick Borne Dis 2019; 10:101265. [PMID: 31447316 DOI: 10.1016/j.ttbdis.2019.101265] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [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: 12/21/2018] [Revised: 07/10/2019] [Accepted: 07/28/2019] [Indexed: 12/30/2022]
Abstract
Here, we report the first confirmed autochthonous tick-borne encephalitis case diagnosed in Moscow in 2016 and describe the detection of tick-borne encephalitis virus (TBEV) in ticks and small mammals in a Moscow park. The paper includes data from two patients who were bitten by TBEV-infected ticks in Moscow city; one of these cases led to the development of the meningeal form of TBE. Both TBEV-infected ticks attacked patients in the same area. We collected ticks and trapped small mammals in this area in 2017. All samples were screened for the presence of pathogens causing tick-borne diseases by PCR. The TBEV-positive ticks and small mammals' tissue samples were subjected to virus isolation. The sequencing of the complete polyprotein gene of the positive samples was performed. A total of 227 questing ticks were collected. TBEV was detected in five specimens of Ixodes ricinus. We trapped 44 small mammals, mainly bank voles (Myodes glareolus) and pygmy field mice (Apodemus uralensis). Two samples of brain tissue from bank voles yielded a positive signal in RT-PCR for TBEV. We obtained six virus isolates from the ticks and brain tissue of a bank vole. Complete genome sequencing showed that the obtained isolates belong to the European subtype and have low diversity with sequence identities as high as 99.9%. GPS tracking showed that the maximum distance between the exact locations where the TBEV-positive ticks were collected was 185 m. We assume that the forest park had been free of TBEV and that the virus was recently introduced.
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Affiliation(s)
- Marat Makenov
- Central Research Institute of Epidemiology, Novogireevskaya st 3-A, 415, Moscow, 111123, Russia.
| | - Lyudmila Karan
- Central Research Institute of Epidemiology, Novogireevskaya st 3-A, 415, Moscow, 111123, Russia
| | - Natalia Shashina
- Sсiеntifiс Rеsеarсh Disinfесtology Institutе, Nauchniy proezd st. 18, Moscow, 117246, Russia
| | - Marina Akhmetshina
- Sсiеntifiс Rеsеarсh Disinfесtology Institutе, Nauchniy proezd st. 18, Moscow, 117246, Russia
| | - Olga Zhurenkova
- Central Research Institute of Epidemiology, Novogireevskaya st 3-A, 415, Moscow, 111123, Russia
| | - Ivan Kholodilov
- Chumakov Institute of Poliomyelitis and Viral Encephalitides (FSBSI "Chumakov FSC R&D IBP RAS), prem. 8, k.17, pos. Institut Poliomyelita, poselenie Moskovskiy, Moscow, 108819, Russia
| | - Galina Karganova
- Chumakov Institute of Poliomyelitis and Viral Encephalitides (FSBSI "Chumakov FSC R&D IBP RAS), prem. 8, k.17, pos. Institut Poliomyelita, poselenie Moskovskiy, Moscow, 108819, Russia; Institute for Translational Medicine and Biotechnology, Sechenov University, Bolshaya Pirogovskaya st, 2, page 4, room 106, Moscow, 119991, Russia
| | - Nina Smirnova
- Central Research Institute of Epidemiology, Novogireevskaya st 3-A, 415, Moscow, 111123, Russia; Lomonosov Moscow State University, Leninskie Gory st. 1-12, MSU, Faculty of Biology, Moscow, 119991, Russia
| | - Yana Grigoreva
- Central Research Institute of Epidemiology, Novogireevskaya st 3-A, 415, Moscow, 111123, Russia
| | - Yanina Yankovskaya
- Pirogov Russian National Research Medical University, Ostrovityanova st. 1, Moscow, 117997, Russia
| | - Marina Fyodorova
- Central Research Institute of Epidemiology, Novogireevskaya st 3-A, 415, Moscow, 111123, Russia
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Smirnova N, Eremenko A, Fesenko T, Kosevich M, Snegir S. UV–Vis spectroscopy and desorption/ionization mass spectrometry as the tools for investigation of adsorbed dye photodegradation. Res Chem Intermed 2019. [DOI: 10.1007/s11164-019-03898-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ulyankina A, Avramenko M, Kusnetsov D, Firestein K, Zhigunov D, Smirnova N. Electrochemical Synthesis of TiO 2
under Pulse Alternating Current: Effect of Thermal Treatment on the Photocatalytic Activity. ChemistrySelect 2019. [DOI: 10.1002/slct.201803367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Anna Ulyankina
- Technology Department; Platov South-Russian State Polytechnic University (NPI); Novocherkassk Russian Federation
| | - Marina Avramenko
- Department of Nanotechnology; Southern Federal University; Rostov-on-Don Russian Federation
| | - Denis Kusnetsov
- College of New Materials and Nanotechnologies; National University of Science and Technology MISIS; Moscow Russian Federation
| | - Konstantin Firestein
- Science and Engineering Faculty; Queensland University of Technology (QUT); Brisbane Australia
| | - Denis Zhigunov
- Center for Photonics and Quantum Materials; Skolkovo Institute of Science and Technology; Moscow Russian Federation
| | - Nina Smirnova
- Technology Department; Platov South-Russian State Polytechnic University (NPI); Novocherkassk Russian Federation
- College of New Materials and Nanotechnologies; National University of Science and Technology MISIS; Moscow Russian Federation
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Linnik O, Chorna N, Smirnova N. Non-porous Iron Titanate Thin Films Doped with Nitrogen: Optical, Structural, and Photocatalytic Properties. Nanoscale Res Lett 2017; 12:249. [PMID: 28381071 PMCID: PMC5380544 DOI: 10.1186/s11671-017-2027-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 03/29/2017] [Indexed: 06/07/2023]
Abstract
The synthesized undoped and nitrogen doped iron titanate films treated at 450 and 500 °C were crystallized forming pseudobrookite and landauite phase as shown by XRD patterns. The presence of urea in the synthesis procedure promoted the crystallization rate. XPS data indicated that iron ions existed in divalent and trivalent forms, and their ratio was changed for nitrogen-doped sample. The formation of the complexes between iron and urea during sol aging with the following reduction of Fe3+ to Fe2+ within calcination can be a reason not only for accumulation of iron onto the surface as shown by EDS but also for twice increase of divalent iron as registered by XPS. The iron titanate films extended the visible light absorption. Two band gap energy values for all iron-contained films were calculated. The photocatalytic response of all iron titanate films treated at 450 °C compared to pure titania films was spectacularly enhanced under UV and visible light. The slight enhance in photocatalytic activity of nitrogen-doped iron titanate films can be explained by the interstitial nitrogen incorporation rather than substitutional.
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Affiliation(s)
- O. Linnik
- Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov, Kyiv, 03680 Ukraine
| | - N. Chorna
- Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov, Kyiv, 03680 Ukraine
| | - N. Smirnova
- Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov, Kyiv, 03680 Ukraine
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16
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Smirnova N, Petrik I, Vorobets V, Kolbasov G, Eremenko A. Sol-gel Synthesis, Photo- and Electrocatalytic Properties of Mesoporous TiO 2 Modified with Transition Metal Ions. Nanoscale Res Lett 2017; 12:239. [PMID: 28363240 PMCID: PMC5374089 DOI: 10.1186/s11671-017-2002-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 03/14/2017] [Indexed: 06/01/2023]
Abstract
Mesoporous nanosized titania films modified with Co2+, Ni2+, Mn3+, and Cu2+ ions have been produced by templated sol-gel method and characterized by optical spectroscopy, X-ray diffraction (XRD), and Brunauer, Emmett, and Teller (BET) surface area measurement. Band gap energy and the position of flat band potentials were estimated by photoelectrochemical measurements. The films doped with transition metals possessed higher photocurrent quantum yield, as well as photo- and electrochemical activity compared to undoped samples. Mn+/TiO2 (M-Co, Ni, Mn, Cu) electrodes with low dopant content demonstrate high efficiency in electrocatalytic reduction of dissolved oxygen. Polarization curves of TiO2, TiO2/Ni2+, TiO2/Co2+/3+, and TiO2/Mn3+ electrodes contain only one current wave (oxygen reduction current). It means that reaction proceeds without the formation of an intermediate product H2O2.
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Affiliation(s)
- N. Smirnova
- O.Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Street, Kyiv, 03680 Ukraine
| | - I. Petrik
- O.Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Street, Kyiv, 03680 Ukraine
| | - V. Vorobets
- Institute of General & Inorganic Chemistry of National Academy of Sciences of Ukraine 32/34 Acad, Palladin Street, Kyiv, 03680 Ukraine
| | - G. Kolbasov
- Institute of General & Inorganic Chemistry of National Academy of Sciences of Ukraine 32/34 Acad, Palladin Street, Kyiv, 03680 Ukraine
| | - A. Eremenko
- O.Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Street, Kyiv, 03680 Ukraine
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17
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Novikova K, Kuriganova A, Leontyev I, Gerasimova E, Maslova O, Rakhmatullin A, Smirnova N, Dobrovolsky Y. Influence of Carbon Support on Catalytic Layer Performance of Proton Exchange Membrane Fuel Cells. Electrocatalysis (N Y) 2017. [DOI: 10.1007/s12678-017-0416-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Ptashko T, Smirnova N, Eremenko A, Oranska E, Huang W. Synthesis and Photocatalytic Properties of Mesoporous TiO2/ZnO Films with Improved Hydrophilicity. ADSORPT SCI TECHNOL 2016. [DOI: 10.1260/026361707781485753] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- T. Ptashko
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - N. Smirnova
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - A. Eremenko
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - E. Oranska
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - W. Huang
- Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A
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Abstract
Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin films were fabricated by the sol—gel technique using the non-ionic amphiphilic triblock copolymer Pluronic P123 as the template. The structure and optical properties of these films were characterized using TEM, low-angle XRD, DTA/TG measurements, UV—vis spectroscopy and hexane adsorption investigations. It was found that addition of ZrO2 into the TiO2 matrix retarded sintering of the films, thereby increasing the specific surface area after treatment up to 500°C. The catalytic activity of the mesoporous TiO2 and TiO2/(5–30%) ZrO2 films in ethanol photo-oxidation increased with increasing specific surface area and surface acidity of the samples.
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Affiliation(s)
- Yu. Gnatyuk
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - N. Smirnova
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - A. Eremenko
- Institute of Surface Chemistry, Ukrainian National Academy of Sciences, 17 General Naumov Str., Kiev 03164, Ukraine
| | - V. Ilyin
- L.V. Pisarzhevsky Institute of Physical Chemistry, Ukrainian National Academy of Sciences, 31 Nauki Str., Kiev 03039, Ukraine
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21
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Myakova N, Rudneva A, Denisov N, Abugova Y, Diakonova Y, Konovalov D, Nechesnyuk A, Rogozhin D, Smirnova N, Samochatova E, Belogurova M, Streneva O, Ponomareva N, Parkhomenko R, Ryskal' O. Treatment of Children and Adolescents with Hodgkin's Lymphoma According to Recommendations of DAL/GPOH-HD Group (Preliminary Results). Klin Padiatr 2014. [DOI: 10.1055/s-0034-1371140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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22
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Verbenko V, Stroyevskaya I, Yurieva N, Stroievskyi V, Smirnova N, Kuzmin A. P-461 - Clinical and diagnostic particulars of initial and late forms of neurosyphilis in southern regions of ukraine. Eur Psychiatry 2012. [DOI: 10.1016/s0924-9338(12)74628-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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23
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Smirnova N, Vorobets V, Linnik O, Manuilov E, Kolbasov G, Eremenko A. Photoelectrochemical and photocatalytic properties of mesoporous TiO2 films modified with silver and gold nanoparticles. SURF INTERFACE ANAL 2010. [DOI: 10.1002/sia.3237] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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Bielefeldt-Ohmann H, Tolnay AE, Reisenhauer C, Hansen T, Smirnova N, Van Campen H. Transplacental Infection with Non-Cytopathic Bovine Viral Diarrhoea Virus Types 1b and 2: Viral Spread and Molecular Neuropathology. J Comp Pathol 2008; 138:72-85. [DOI: 10.1016/j.jcpa.2007.10.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 10/27/2007] [Indexed: 11/24/2022]
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25
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Van de Walle J, Aksouh F, Ames F, Behrens T, Bildstein V, Blazhev A, Cederkäll J, Clément E, Cocolios TE, Davinson T, Delahaye P, Eberth J, Ekström A, Fedorov DV, Fedosseev VN, Fraile LM, Franchoo S, Gernhauser R, Georgiev G, Habs D, Heyde K, Huber G, Huyse M, Ibrahim F, Ivanov O, Iwanicki J, Jolie J, Kester O, Köster U, Kröll T, Krücken R, Lauer M, Lisetskiy AF, Lutter R, Marsh BA, Mayet P, Niedermaier O, Nilsson T, Pantea M, Perru O, Raabe R, Reiter P, Sawicka M, Scheit H, Schrieder G, Schwalm D, Seliverstov MD, Sieber T, Sletten G, Smirnova N, Stanoiu M, Stefanescu I, Thomas JC, Valiente-Dobón JJ, Van Duppen P, Verney D, Voulot D, Warr N, Weisshaar D, Wenander F, Wolf BH, Zielińska M. Coulomb excitation of neutron-rich Zn isotopes: first observation of the 2(1)+ state in 80Zn. Phys Rev Lett 2007; 99:142501. [PMID: 17930664 DOI: 10.1103/physrevlett.99.142501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Indexed: 05/25/2023]
Abstract
Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2(1)+ state in 78Zn could be firmly established and for the first time the 2+ --> 0(1)+ transition in 80Zn was observed at 1492(1) keV. B(E2,2(1)+ --> 0(1)+) values were extracted for (74,76,78,80)Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni.
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Affiliation(s)
- J Van de Walle
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Leuven, Belgium
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26
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Stefanescu I, Georgiev G, Ames F, Aystö J, Balabanski DL, Bollen G, Butler PA, Cederkäll J, Champault N, Davinson T, De Maesschalck A, Delahaye P, Eberth J, Fedorov D, Fedosseev VN, Fraile LM, Franchoo S, Gladnishki K, Habs D, Heyde K, Huyse M, Ivanov O, Iwanicki J, Jolie J, Jonson B, Kröll T, Krücken R, Kester O, Köster U, Lagoyannis A, Liljeby L, Lo Bianco G, Marsh BA, Niedermaier O, Nilsson T, Oinonen M, Pascovici G, Reiter P, Saltarelli A, Scheit H, Schwalm D, Sieber T, Smirnova N, Van De Walle J, Van Duppen P, Zemlyanoi S, Warr N, Weisshaar D, Wenander F. Coulomb excitation of 68,70Cu: first use of postaccelerated isomeric beams. Phys Rev Lett 2007; 98:122701. [PMID: 17501116 DOI: 10.1103/physrevlett.98.122701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Indexed: 05/15/2023]
Abstract
We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. Gamma rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the pi2p3/2 nu 1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6--->4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N approximately 40.
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Affiliation(s)
- I Stefanescu
- Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
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27
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Klefortova I, Shamkhalova M, Smirnova N, Shestakova M, Alpenidze V, Tugeeva E, Buziashvili U. We-P11:48 Prevalence of renal artery stenosis in type 2 diabetes. ATHEROSCLEROSIS SUPP 2006. [DOI: 10.1016/s1567-5688(06)81404-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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28
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Gayvoronsky V, Timoshenko V, Brodyn M, Galas A, Nepijko SA, Dittrich T, Koch F, Petrik I, Smirnova N, Eremenko A, Klimenkov M. Giant nonlinear optical response application for nanoporous titanium dioxide photocatalytic activity monitoring. ACTA ACUST UNITED AC 2005. [DOI: 10.1002/pssc.200461150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Skurkovich S, Boiko A, Beliaeva I, Buglak A, Alekseeva T, Smirnova N, Kulakova O, Tchechonin V, Gurova O, Deomina T, Favorova O, Skurkovich B, Gusev E. Randomized study of antibodies to IFN-γ and TNF-α in secondary progressive multiple sclerosis. ACTA ACUST UNITED AC 2001. [DOI: 10.1191/135245801681137960] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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30
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Skurkovich S, Boiko A, Beliaeva I, Buglak A, Alekseeva T, Smirnova N, Kulakova O, Tchechonin V, Gurova O, Deomina T, Favorova OO, Skurkovic B, Gusev E. Randomized study of antibodies to IFN-gamma and TNF-alpha in secondary progressive multiple sclerosis. Mult Scler 2001; 7:277-84. [PMID: 11724442 DOI: 10.1177/135245850100700502] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Studies of cytokines in multiple sclerosis (MS) have shown that immune mechanisms connected with disturbance of the synthesis of cytokines probably play critical roles in the initiation and prolongation of MS. In a double-blind, placebo-controlled trial, 45 patients with active secondary progressive MS were randomized to three groups of 15 patients, each receiving a short course of antibodies to IFN-gamma, to tumor necrosis factor (TNF)-alpha, or a placebo. After 12 months with analysis of disability (Expanded Disability Status Scale scores), accompanied by interval determinations of lymphocyte subpopulations, cytokine production levels, MRI, and evoked potentials, it was found that only patients who received antibodies to IFN-gamma showed statistically significant improvement compared to the placebo group--a significant increase in the number of patients without confirmed disability progression. This was supported by MRI data (a decrease in the number of active lesions) and systemic changes in cytokine status (a decrease in IL-1beta, TNF-alpha, and IFN-gamma concentrations in supernatants of actvated blood cells of these MS patients and an increase in TGF-beta production). Neutralization of IFN-gamma could be a new approach to treating secondary progressive MS. Long-term administration of humanized monoclonal antibodies to IFN-gamma and simultaneous use of antibodies to IFN-gamma together with IFN-beta products are planned.
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Affiliation(s)
- S Skurkovich
- Advanced Biotherapy Laboratories, Rockville, MD, USA
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31
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Abstract
Beta-ketoacyl-acyl carrier protein (ACP) synthase III (KASIII) catalyzes the first elongation step in straight-chain fatty acid (SCFA) biosynthesis in Escherichia coli. Overproduction of the corresponding KASIII gene, or the Brassica napus KASIII gene has previously been observed to lead to an increase in the amount of shorter-chain fatty acids produced by E. coli. In this study it is shown that overexpression of the KASIII gene, which initiates branched-chain fatty acid (BCFA) in Streptomyces glaucescens, does not lead to a change in the fatty acid profiles of E. coli. E. coli produces trace levels of BCFAs when grown in the presence of isobutyric acid, but the amounts of these are not significantly altered by expression of the S. glaucescens KASIII gene. In contrast, the amounts of BCFAs produced from isobutyryl CoA in vitro by E. coli cell-free extracts can be increased at least four-fold by the presence of the S. glaucescens KASIII. These observations suggest that in vivo production of isopalmitate by E. coli expressing the S. glaucescens KASIII is limited by availability of the appropriate BCFA biosynthetic primers.
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Affiliation(s)
- N Smirnova
- Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, VA 23219, USA
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32
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Smirnova N, Reynolds KA. Engineered fatty acid biosynthesis in Streptomyces by altered catalytic function of beta-ketoacyl-acyl carrier protein synthase III. J Bacteriol 2001; 183:2335-42. [PMID: 11244075 PMCID: PMC95142 DOI: 10.1128/jb.183.7.2335-2342.2001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Streptomyces glaucescens beta-ketoacyl-acyl carrier protein (ACP) synthase III (KASIII) initiates straight- and branched-chain fatty acid biosynthesis by catalyzing the decarboxylative condensation of malonyl-ACP with different acyl-coenzyme A (CoA) primers. This KASIII has one cysteine residue, which is critical for forming an acyl-enzyme intermediate in the first step of the process. Three mutants (Cys122Ala, Cys122Ser, Cys122Gln) were created by site-directed mutagenesis. Plasmid-based expression of these mutants in S. glaucescens resulted in strains which generated 75 (Cys122Ala) to 500% (Cys122Gln) more straight-chain fatty acids (SCFA) than the corresponding wild-type strain. In contrast, plasmid-based expression of wild-type KASIII had no effect on fatty acid profiles. These observations are attributed to an uncoupling of the condensation and decarboxylation activities in these mutants (malonyl-ACP is thus converted to acetyl-ACP, a SCFA precursor). Incorporation experiments with perdeuterated acetic acid demonstrated that 9% of the palmitate pool of the wild-type strain was generated from an intact D(3) acetyl-CoA starter unit, compared to 3% in a strain expressing the Cys122Gln KASIII. These observations support the intermediacy of malonyl-ACP in generating the SCFA precursor in a strain expressing this mutant. To study malonyl-ACP decarboxylase activity in vitro, the KASIII mutants were expressed and purified as His-tagged proteins in Escherichia coli and assayed. In the absence of the acyl-CoA substrate the Cys122Gln mutant and wild-type KASIII were shown to have comparable decarboxylase activities in vitro. The Cys122Ala mutant exhibited higher activity. This activity was inhibited for all enzymes by the presence of high concentrations of isobutyryl-CoA (>100 microM), a branched-chain fatty acid biosynthetic precursor. Under these conditions the mutant enzymes had no activity, while the wild-type enzyme functioned as a ketoacyl synthase. These observations indicate the likely upper and lower limits of isobutyryl-CoA and related acyl-CoA concentrations within S. glaucescens.
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Affiliation(s)
- N Smirnova
- Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia 23219, USA
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33
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Eremenko A, Smirnova N, Rusina O, Linnik O, Eremenko T, Spanhel L, Rechthaler K. Photophysical properties of organic fluorescent probes on nanosized TIO 2 /SIO 2 systems prepared by the sol–gel method. J Mol Struct 2000. [DOI: 10.1016/s0022-2860(00)00448-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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34
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Scott JM, Smirnova N, Haldenwang WG. A Bacillus-specific factor is needed to trigger the stress-activated phosphatase/kinase cascade of sigmaB induction. Biochem Biophys Res Commun 1999; 257:106-10. [PMID: 10092518 DOI: 10.1006/bbrc.1999.0418] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The general stress regulon of Bacillus subtilis is controlled by the transcription factor sigmaB. Environmental stress activates sigmaB via a phosphatase/kinase cascade that triggers sigmaB's release from an anti sigma factor complex. To determine if the members of the phosphatase/kinase cascade are sufficient to detect environmental stress and activate sigmaB, we expressed sigmaB and its regulators in E. coli. In E. coli, as in B. subtilis, the intact collection of regulators silenced sigmaB, while allowing sigmaB to be active if the cascade's most upstream negative regulator was deleted. The regulators could not, however, activate sigmaB in response to ethanol treatment or heat shock. In other experiments, the GroEL and DnaK chaperones, known to be important in controlling stress sigma factors in E. coli, were found to be unimportant for sigmaB activity in B. subtilis. The findings argue that stress induction of sigmaB requires novel factors that are B. subtilis specific.
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Affiliation(s)
- J M Scott
- Department of Microbiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284-7758, USA
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Smirnova N, Scott J, Voelker U, Haldenwang WG. Isolation and characterization of Bacillus subtilis sigB operon mutations that suppress the loss of the negative regulator RsbX. J Bacteriol 1998; 180:3671-80. [PMID: 9658013 PMCID: PMC107338 DOI: 10.1128/jb.180.14.3671-3680.1998] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/1998] [Accepted: 05/11/1998] [Indexed: 02/08/2023] Open
Abstract
sigmaB, a transcription factor that controls the Bacillus subtilis general stress response regulon, is activated by either a drop in intracellular ATP or exposure to environmental stress. RsbX, one of seven sigmaB regulators (Rsb proteins) whose genes are cotranscribed with sigmaB, is a negative regulator in the stress-dependent activation pathway. To better define the interactions that take place among the Rsb proteins, we analyzed sigB operon mutations which suppress the high-level sigmaB activity that normally accompanies the loss of RsbX. Each of these mutations was in one of three genes (rsbT, -U, and -V) which encode positive regulators of sigmaB, and they all defined amino acid changes which either compromised the activities of the mutant Rsbs or affected their ability to accumulate. sigmaB activity remained inducible by ethanol in several of the RsbX- suppressor strains. This finding supports the notion that RsbX is not needed as the target for sigmaB activation by at least some stresses. sigmaB activity in several RsbX- strains with suppressor mutations in rsbT or -U was high during growth and underwent a continued, rather than a transient, increase following stress. Thus, RsbX is likely responsible for maintaining low sigmaB activity during balanced growth and for reestablishing sigmaB activity at prestress levels following induction. Although RsbX likely participates in limiting the sigmaB induction response, a second mechanism for curtailing unrestricted sigmaB activation was suggested by the sigmaB induction profile in two suppressor strains with mutations in rsbV. sigmaB activity in these mutants was stress inducible but transient, even in the absence of RsbX.
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Affiliation(s)
- N Smirnova
- Department of Microbiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284-7758, USA
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Voelker U, Luo T, Smirnova N, Haldenwang W. Stress activation of Bacillus subtilis sigma B can occur in the absence of the sigma B negative regulator RsbX. J Bacteriol 1997; 179:1980-4. [PMID: 9068644 PMCID: PMC178922 DOI: 10.1128/jb.179.6.1980-1984.1997] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Environmental stress activates sigma B, the general stress response sigma factor of Bacillus subtilis, by a pathway that is negatively controlled by the RsbX protein. To determine whether stress activation of sigma B occurs by a direct effect of stress on RsbX, we constructed B. subtilis strains which synthesized various amounts of RsbX or lacked RsbX entirely and subjected these strains to ethanol stress. Based on the induction of a sigma B-dependent promoter, stress activation of sigma B can occur in the absence of RsbX. Higher levels of RsbX failed to detectably influence stress induction, but reduced levels of RsbX resulted in greater and longer-lived sigma B activation. The data suggest that RsbX is not a direct participant in the sigma B stress induction process but rather serves as a device to limit the magnitude of the stress response.
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Affiliation(s)
- U Voelker
- Deparment of Microbiology, University of Texas Health Science Center, San Antonio 78284-7758, USA
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37
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Popov V, Sutáková G, Rehácek J, Smirnova N, Daiter A. Coxiella and Rickettsiella: comparison of ultrastructure with special reference to their envelope. Acta Virol 1991; 35:573-9. [PMID: 1687641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ultrastructure of Rickettsiella phytoseiuli (R.p.) multiplying in female ticks Dermacentor reticulatus was compared with that of Coxiella burnetii (C.b.) in the same ticks and in mice. C.b. in ticks and mice were always represented by 2 main cell types: small dense round or rod-like cells (DC) and larger bacteria-like cells (BC). DC were surrounded with a characteristic five-layered 20 nm thick envelope. Under the envelope DC had a stack of parallel intracytoplasmic membranes with a periodicity 5-6 nm. R.p. in tick fat body and synganglion were also inside phagosomes and formed 6 sequentially developing cell forms: dense (elementary), intermediate, bacterial, giant, and crystal-forming in which small dark bodies (initial particles) condensed. Two of them--dense and bacterial--corresponded to DC and BC of C.b. The DC envelope structure of R.p. was strikingly similar to that of some C.b. DC in mouse. We confirmed the general morphologic similarities in the structure of C.b. and R.p. DC and that of C.b. BC and intermediate cells of R.p. The envelope structure of DC type was found in other gracilicute bacteria and is supposed to have no taxonomic value but to be a reflection of population heterogeneity.
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Affiliation(s)
- V Popov
- Gamaleya Institute of Epidemiology and Microbiology, Moscow, U.S.S.R
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