Solubilization of drugs using beta-cyclodextrin: Experimental data and modeling

Many drug candidates fail to complete the entire drug development process because of poor physicochemical properties. Solubility is an important physicochemical property which plays a vital role in various stages of drug discovery and development. Several methods have been proposed to enhance the solubility of drugs, and complex formation with cyclodextrins is among them. Beta-cyclodextrin (βCD) is a common excipient for solubilization of drugs. The aim of this study is to develop the mechanistic QSPR models to predict the solubility enhancement of a drug in the presence of βCD. In this study, the solubility enhancement of some drugs in the presence of 10mM βCD at 25°C was experimentally determined or collected from the literature. Two different models to predict the solubilization by βCD were developed by binary logistic regression using structural properties of drugs with more than 80% accuracy. Polar surface area and excess molar refraction are the main parameters for estimating solubilization by βCD. Moreover, other descriptors related to hydrophobicity and the capability of hydrogen bonding formation of molecules could improve the accuracy of the established models.

Effects of crosslinking with sodium trimetaphosphate on structural, physicochemical, rheological and in vitro digestibility properties of purple sweet potato starch

Purple sweet potato starch (PSPS) was modified using different amounts of sodium trimetaphosphate (0, 3-12%). Phosphorus content, crosslinking (CL), and substitution levels increased after modification. CL led to gradual agglomeration with each other through adhesion, compared to 0% STMP. X-ray diffraction did not change, but crystalline properties, swelling index, and peak viscosity increased, and solubility and glycaemic index decreased after crosslinking. Crosslinking increased, leading to a decrease of greater significance at 3% CL. Resistant starch was increased from 60.51 to 83.32%. G' and G'' values for crosslinking starch samples varied from 3086.00-5507.50 Pa and 513.92-800.30 Pa, respectively, after sweep test. The flow behavior index < 1 indicates that CL starch pastes are shear-thin. Positive and negative correlations were observed between gelatinized starch enthalpy and RS and between SDS and GI, respectively. The results lay the groundwork to comprehend the properties and relationships of CLPSPS and promote its possible use in foods.

The analysis of the structural parameter influences on measurement errors in a binocular 3D reconstruction system: a portable 3D system

This study used an analytical model to investigate the factors that affect the reconstruction accuracy composed of the baseline length, lens focal length, the angle between the optical axis and baseline, and the field of the view angle. Firstly, the theoretical expressions of the above factors and measurement errors are derived based on the binocular three-dimensional reconstruction model. Then, the structural parameters' impact on the error propagation coefficient is analyzed and simulated using MATLAB software. The results show that structural parameters significantly impact the error propagation coefficient, and the reasonable range of structural parameters is pointed out. When the angle between the optical axis of the binocular camera and the baseline is between 30° and 55°, the ratio of the baseline length to the focal length can be reasonably reduced. In addition, using the field angle of the view that does not exceed 20° could reduce the error propagation coefficient. While the angle between the binocular optical axis and the baseline is between 40° and 50°, the reconstruction result has the highest accuracy, changing the angle out of this range will lead to an increase in the reconstruction error. The angle between the binocular optical axis and the baseline changes 30° through 60° leads to the error propagation coefficient being in a lower range. Finally, experimental verification and simulation results show that selecting reasonable structural parameters could significantly reduce measurement errors. This study proposes a model that constructs a binocular three-dimensional reconstruction system with high precision. A portable three-dimensional reconstruction system is built in the article.

Transition metal-based nanoparticles as potential antimicrobial agents: recent advancements, mechanistic, challenges, and future prospects

Bacterial transmission is considered one of the potential risks for communicable diseases, requiring promising antibiotics. Traditional drugs possess a limited spectrum of effectiveness, and their frequent administration reduces effectiveness and develops resistivity. In such a situation, we are left with the option of developing novel antibiotics with higher efficiency. In this regard, nanoparticles (NPs) may play a pivotal role in managing such medical situations due to their distinct physiochemical characteristics and impressive biocompatibility. Metallic NPs are found to possess extraordinary antibacterial effects that are useful in vitro as well as in vivo as self-modified therapeutic agents. Due to their wide range of antibacterial efficacy, they have potential therapeutic applications via diverse antibacterial routes. NPs not only restrict the development of bacterial resistance, but they also broaden the scope of antibacterial action without binding the bacterial cell directly to a particular receptor with promising effectiveness against both Gram-positive and Gram-negative microbes. This review aimed at exploring the most relevant types of metal NPs employed as antimicrobial agents, particularly those based on Mn, Fe, Co, Cu, and Zn metals, and their antimicrobial mechanisms. Further, the challenges and future prospects of NPs in biological applications are also discussed.

Introducing a novel C50N10 azafullerene with chained nitrogen atoms on a buckyball pole: structure, stability, vibration, and electronic properties

CONTEXT

Fullerenes are of high significance due to their unique chemical properties and various applications in technology, particularly materials science, drug delivery, electronics, and nanoelectronics. In the recent years, many attempts have been focused to introduce new heteroatom-doped fullerenes having advanced chemical properties and tunable electronic traits, which make them a potential candidate for application in many branches of sciences. In this study, a novel C₅₀N₁₀ azafullerene with a fascinating structure of chained nitrogen atoms on a buckyball pole, with different electronic and optical properties compared to its other analogs, is introduced and trace of N-N substructures on the surface of C₆₀ fullerene cage is investigated. For this molecule, four structural isomers including 3 structures with chain N atoms on a fullerene buckyball pole (NP isomers) and one isomer with separated N atoms (SN isomer) have been studied. All isomers have been studied with and without symmetry constraints, and the symmetry influence on the structure and stability of each isomer has been investigated. Although the studied NP structures have lower stability than the SN isomer, some reasons (such as their more all-carbon hexagonal rings, breaking some of their N-N bonds for partial opening of the cage and creating bigger rings in order to get rid of the unfavorable strain, as well as decreasing the N-N lone pair repulsions) lead to the acceptable stability of these structures with the bonded N atoms. The results of atomization energy and vibrational frequency calculations indicate that isomers with the bonded N atoms have acceptable stabilities and do not decompose into their constituent components. Investigation on the structural parameters demonstrates important roles of the number of all-carbon hexagonal rings, the number of N-N junction, and the molecule symmetry in the stability of the structures with the bonded N atoms. Study on the electronic and optical properties indicates that the target structures exhibit high electronic polarizability, relatively small HOMO/LUMO gap, high first- and second-order hyperpolarizability, and also large third-order nonlinear optical properties.

METHODS

All calculations have been performed using Gaussian G09 software using density functional theory (DFT) approach. Three-parameter Beck hybrid exchange functional (B3) hybridized with nonlocal correlation functional of Lee, Yang, and Parr (LYP) has been employed as the level of DFT calculations. All optimizations have been performed at double-zeta polarized (DZP) split valence 6-31G(d,p) and also at split valence TZP 6-311G(d,p) basis sets. The global minimum structures have been confirmed by frequency calculations at the same level of optimizations. The natural bond orbital (NBO) analyses, frontier orbital surfaces imaging, atomic charges, and charge transfer analyses have been achieved by GenNBO program package.

Computational prediction of protein folding rate using structural parameters and network centrality measures

Protein folding is a complex physicochemical process whereby a polymer of amino acids samples numerous conformations in its unfolded state before settling on an essentially unique native three-dimensional (3D) structure. To understand this process, several theoretical studies have used a set of 3D structures, identified different structural parameters, and analyzed their relationships using the natural logarithmic protein folding rate (ln(k_f)). Unfortunately, these structural parameters are specific to a small set of proteins that are not capable of accurately predicting ln(k_f) for both two-state (TS) and non-two-state (NTS) proteins. To overcome the limitations of the statistical approach, a few machine learning (ML)-based models have been proposed using limited training data. However, none of these methods can explain plausible folding mechanisms. In this study, we evaluated the predictive capabilities of ten different ML algorithms using eight different structural parameters and five different network centrality measures based on newly constructed datasets. In comparison to the other nine regressors, support vector machine was found to be the most appropriate for predicting ln(k_f) with mean absolute differences of 1.856, 1.55, and 1.745 for the TS, NTS, and combined datasets, respectively. Furthermore, combining structural parameters and network centrality measures improves the prediction performance compared to individual parameters, indicating that multiple factors are involved in the folding process.

Optimized structural parameters and heat extraction capacity of a mixing device for constant pressure CO2 mineralization using alkaline waste

Alkaline waste such as calcium carbide slag is an ideal material for mineralizing CO₂ and promoting atmospheric carbon reduction. In this study, the structural parameters of a mixing device and a thermal extraction method for the high-efficiency mineralization of CO₂ using alkaline waste were optimized. First, the influence of structural parameters was studied by means of numerical simulation, and it was found that when the length-diameter ratio, blade angle, spacing, and diameter of the mixing device were 3, 15, 6 cm, and 14 cm respectively, 2.14 t CO₂ can be mineralized within 1 h. The amount of heat extracted from mineralization of 1 t CO₂ reached 189.60 MJ. In addition, the winding configuration of the heat pipe, which is beneficial for extracting more reaction heat, was optimal, and a model of the relationship between the heat pipe outlet water temperature and flow velocity at the outlet of the heat pipe was established. This study provides theoretical guidance for the field application of alkaline waste for high-efficiency mineralization of CO₂, which can accelerate the realization of peak CO₂ emissions and carbon neutrality.

Mechanical properties analysis of medical endodontic instruments based on parameterization

To study the relationship between structural parameters and mechanical properties of endodontic instruments, the T02004B25 nickel-titanium endodontic instrument was selected for bending and torsion tests and finite element simulation analysis, which demonstrated the feasibility of simulation analysis method. Then based on the idea of parametric design, the models of the endodontic instruments with different structural parameters (cross-section, pitch, taper) were established, and the bending-torsion performance simulation analysis was completed. The results showed that the mechanical properties of endodontic instruments with different structural parameters are different. It is necessary to find the optimal parameters for different structure parameters of endodontic instruments to maximize their service life.

In situ COD monitoring with use of a hybrid of constructed wetland-microbial fuel cell

The hybrid system of constructed wetland and microbial fuel cell (CW-MFC) used as a biosensor is becoming a new research focus with the advantage of resisting the shock loading and enriching more electricigens. In this study, a structural parameter S integrating the size, the position and the spacing of the anode and the cathode was proposed. And the electrogenesis and biosensing performances of the vertical flow CW-MFC biosensors were evaluated at different S values. The results showed that all the three biosensors could achieve good monitoring for COD (R² > 0.97). And the coulombic yield was more suitable for the response signal than output voltage. But different biosensing properties including detection signal, detection range, detection time, correlation fitting degree and sensitivity were also displayed. Further, in order to optimize the biosensing performance, the coulombic yield in stable voltage stage (Qs) was proposed which can shorten the detection time by 70% at most. On the anodes, abundant nitrogen-transforming bacteria (NTB) were enriched as well as electrochemically active bacteria (EAB). The competition of NTB for substrates and electrons with EAB disturbed the output voltage signal but not affect the stability of coulombic yield signal. Moreover, the significant linear correlation between the S values and the ratios of EAB to NTB colonized both on anodes and on cathodes indicated the differences of the electricity generation and biosensing performance at the different structural parameters.

Human kidney graft survival correlates with structural parameters in baseline biopsies: a quantitative observational cohort study with more than 14 years' follow-up

This prospective cohort study evaluates associations between structural and ultrastructural parameters in baseline biopsies from human kidney transplants and long-term graft survival after more than 14 years' follow-up. Baseline kidney graft biopsies were obtained prospectively from 54 consecutive patients receiving a kidney transplant at a single institution. Quantitative measurements were performed on the baseline biopsies by computer-assisted light microscopy and electron microscopy. Stereology-based techniques estimated the fraction of interstitial tissue, the volume of glomeruli, mesangial fraction, and basement membrane thickness of glomerular capillaries. The fraction of occluded glomeruli and scores according to the Banff classification were achieved. Kidney graft survival was analyzed by Kaplan-Meier estimates and Cox regression. Association to long-term kidney function was also analyzed. The long-term surviving kidney transplants were characterized at implantation by less arteriolar hyaline thickening (P < 0.001) and less interstitial fibrosis (P = 0.001), as well as a lower fraction of occluded glomeruli (P = 0.004) and lower glomerular volume (P = 0.03). At the latest follow-up, eGFR was decreased by 12 ml/min/1.73 m² per unit increase in the score for arteriolar hyalinosis at implantation (P = 0.02), and eGFR was decreased by 19 ml/min/1.73 m² per 10⁶ μm³ increase in glomerular volume at baseline (P = 0.03). The unbiased Cavalieri estimate of glomerular volume and the ultrastructural parameters are the first to be evaluated in a cohort study with prospective follow-up for more than 14 years. The study shows that baseline biopsies from human kidney grafts contain extraordinary long-term prognostic information, and it highlights the importance of these intrinsic graft factors.

Counting Linear Extensions: Parameterizations by Treewidth

We consider the # P -complete problem of counting the number of linear extensions of a poset ( # LE ) ; a fundamental problem in order theory with applications in a variety of distinct areas. In particular, we study the complexity of # LE parameterized by the well-known decompositional parameter treewidth for two natural graphical representations of the input poset, i.e., the cover and the incomparability graph. Our main result shows that # LE is fixed-parameter intractable parameterized by the treewidth of the cover graph. This resolves an open problem recently posed in the Dagstuhl seminar on Exact Algorithms. On the positive side we show that # LE becomes fixed-parameter tractable parameterized by the treewidth of the incomparability graph.

Understanding the synergistic effect and the main factors influencing the enzymatic hydrolyzability of corn stover at low enzyme loading by hydrothermal and/or ultrafine grinding pretreatment

A thorough assessment of the microstructural changes and synergistic effects of hydrothermal and/or ultrafine grinding pretreatment on the subsequent enzymatic hydrolysis of corn stover was performed in this study. The mechanism of pretreatment was elucidated by characterizing the particle size, specific surface area (SSA), pore volume (PV), average pore size, cellulose crystallinity (CrI) and surface morphology of the pretreated samples. In addition, the underlying relationships between the structural parameters and final glucose yields were elucidated, and the relative significance of the factors influencing enzymatic hydrolyzability were assessed by principal component analysis (PCA). Hydrothermal pretreatment at a lower temperature (170 °C) combined with ultrafine grinding achieved a high glucose yield (80.36%) at a low enzyme loading (5 filter paper unit (FPU)/g substrate) which is favorable. The relative significance of structural parameters in enzymatic hydrolyzability was SSA > PV > average pore size > CrI/cellulose > particle size. PV and SSA exhibited logarithmic correlations with the final enzymatic hydrolysis yield.

DFT studies of structural and some spectral parameters of copper(II) complexes with N,N,N',N″-tetrakis (2-hydroxyethyl/propyl) ethylenediamine and tris(2-hydroxyethyl)amine

The structures and some spectral parameters of three copper(II) complexes; [Cu(THEEN)(H2O)](PIC)2 (1), [Cu(THPEN)] (PIC)2 C3H8O (2) and [Cu(TEAH3)(PIC)] (PIC)⋅(H2O) (3), previously synthesized and characterized by X-ray diffraction, are here computationally studied by using density functional theory (DFT) in its hybrid form B3LYP. In these complexes, THEEN is N,N,N',N″-tetrakis(2-hydroxyethyl) ethylenediamine and THPEN is N,N,N',N″-tetrakis(2-hydroxypropyl) ethylenediamine, tetrapodal ligands and TEAH3 is tris(2-hydroxyethyl)amine, a tripodal ligand. The primary coordination sphere of copper(II) ion in complexes (1), (2) and (3) are optimized, structural parameters are calculated, vibrational bands are assigned and energy gaps of frontier orbital (HOMO-LUMO) have been calculated with B3LYP/6-31G/LANL2DZ level of theory using DMSO as solvent. The calculated geometric and spectral results reproduced the experimental data with well agreement. Theoretical calculated molecular orbitals (HOMO-LUMO) and their energies have been calculated that suggest charge transfer occurs within the complexes.