Quantum-Chemical Quasi-Docking for Molecular Dynamics Calculations

The quantum quasi-docking procedure is used to compare the docking accuracies of two quantum-chemical semiempirical methods, namely, PM6-D3H4X and PM7. Quantum quasi-docking is an approximation to quantum docking. In quantum docking, it is necessary to search directly for the global minimum of the energy of the protein-ligand complex calculated by the quantum-chemical method. In quantum quasi-docking, firstly, we look for a wide spectrum of low-energy minima, calculated using the MMFF94 force field, and secondly, we recalculate the energies of all these minima using the quantum-chemical method, and among these recalculated energies we determine the lowest energy and the corresponding ligand position. Both PM6-D3H4X and PM7 are novel methods that describe well-dispersion interactions, hydrogen and halogen bonds. The PM6-D3H4X and PM7 methods are used with the COSMO implicit solvent model as it is implemented in the MOPAC program. The comparison is made for 25 high quality protein-ligand complexes. Firstly, the docking positioning accuracies have been compared, and we demonstrated that PM7+COSMO provides better positioning accuracy than PM6-D3H4X. Secondly, we found that PM7+COSMO demonstrates a much higher correlation between the calculated and measured protein–ligand binding enthalpies than PM6-D3H4X. For future quantum docking PM7+COSMO is preferable, but the COSMO model must be improved.

Chemical and chemoenzymatic routes to bridged homoarabinofuranosylpyrimidines: Bicyclic AZT analogues

Conformationally restricted diastereomeric homoarabinofuranosylpyrimidines (AZT analogue), i.e., (5′R)-3′-azido-3′-deoxy-2′-O,5′-C-bridged-β-ᴅ-homoarabinofuranosylthymine and -uracil had been synthesized starting from diacetone ᴅ-glucofuranose following chemoenzymatic and chemical routes in 34–35% and 24–25% overall yields, respectively. The quantitative and diastereoselective acetylation of primary hydroxy over two secondary hydroxy groups present in the key nucleoside precursor was mediated with Lipozyme® TL IM in 2-methyltetrahydrofuran following a chemoenzymatic pathway. Whereas, the protection of the primary hydroxy over the lone secondary hydroxy group in the key azido sugar precursor was achieved using bulky tert-butyldiphenylsilyl chloride (TBDPS-Cl) in pyridine in 92% yield following a chemical synthetic pathway. The chemoenzymatic method was found to be superior over the chemical method in respect of the number of synthetic steps and overall yield of the final product.

Synthesis And Studied Structural and Morphological Properties of 1-Dimensional Zno-Ag2O-Ag Nanowire

1-dimensional zinc oxide (ZnO) - silver oxide (Ag2O) – silver (Ag) nanowire was prepared using a simple and inexpensive bottom-up chemical method. X-ray diffraction (XRD) results showed the presence of diffraction peaks of ZnO and Ag2O with hexagonal wurtzite phase of ZnO. Energy Dispersive X-ray (EDX) results showed the presence of energy peaks of Zinc (Zn), Silver (Ag), and Oxygen (O) elements. Filed Emission Scanning Electron Microscopy (FE-SEM) results showed that the surface morphology is nanowire (1-dimensional structure) with shapes similar to hedgehog spines and have small nanoscale diameters. The present work represents a promising step in the preparation of a 1-dimensional nanowire.

CHEMICAL CONTROL OF PEACHES FROM CLASTEROSPORIOSIS IN THE CONDITIONS OF THE REPUBLIC OF UZBEKISTAN

Peach varieties Istikbol and Gulnoz were found to be resistant to clasterosporiosis. The incidence rate ranged from 13.0 to 45.0%, with the severity of the disease from 8.0 to 22.7%. In the fight against clasterosporiosis, the chemical method is considered the most effective. For chemical protection, it is recommended early spring triple treatment of trees in the following terms: 1 - before the buds swell; 2 - after blooming of trees; 3 - two weeks after blooming, with one of the following fungicides: Skor 250 EC (normally 0.02% suspension), Kresoxin 50% WDG. (0.02%), Topsin-M 70% WP (0.1%) and Falcon 46% EC (0.05%) against peach clasterosporiosis. KEYWORDS: peach, fungus, disease, clasterosporiosis, fungicide, efficiency, productivity

Macrophages break interneuromast cell quiescence by intervening the inhibition of Schwann cells in zebrafish lateral line

In the zebrafish lateral line system, interneuromast cells (INCs) between neuromasts are normally kept quiescent by underlying Schwann cells (SWCs). Upon severe injuries that cause the complete loss of an entire NM, INCs can occasionally differentiate into NMs but how they escape from the inhibition by SWCs is still unclear. Using a genetic/chemical method to specifically ablate a neuromast, we found a small portion of larvae can regenerate a new neuromast, but the regeneration was hindered by inhibiting macrophages. We also demonstrated that the inhibition of macrophage can reduce the percentage of tail fin-amputated larvae to regenerate a new NM. By in toto imaging, we further discovered heterogeneities in macrophage behavior and distribution along lateral line. We witnessed the crawling of macrophages in between injured lateral line and SWCs during regeneration and also in between the second primordium and the first mature lateral line during development. It implies that macrophages may physically separate and alleviate the inhibition from pLLn and SWCs to break the quiescence of INCs during regeneration and development in the zebrafish lateral line.

Nanomaterial by Sol-Gel Method: Synthesis and Application

The sol-gel process is a more chemical method (wet chemical method) for the synthesis of various nanostructures, especially metal oxide nanoparticles. In this method, the molecular precursor (usually metal alkoxide) is dissolved in water or alcohol and converted to gel by heating and stirring by hydrolysis/alcoholysis. Since the gel obtained from the hydrolysis/alcoholysis process is wet or damp, it should be dried using appropriate methods depending on the desired properties and application of the gel. For example, if it is an alcoholic solution, the drying process is done by burning alcohol. After the drying stage, the produced gels are powdered and then calcined. The sol-gel method is a cost-effective method and due to the low reaction temperature there is good control over the chemical composition of the products. The sol-gel method can be used in the process of making ceramics as a molding material and can be used as an intermediate between thin films of metal oxides in various applications. The materials obtained from the sol-gel method are used in various optical, electronic, energy, surface engineering, biosensors, and pharmaceutical and separation technologies (such as chromatography). The sol-gel method is a conventional and industrial method for the synthesis of nanoparticles with different chemical composition. The basis of the sol-gel method is the production of a homogeneous sol from the precursors and its conversion into a gel. The solvent in the gel is then removed from the gel structure and the remaining gel is dried. The properties of the dried gel depend significantly on the drying method. In other words, the “removing solvent method” is selected according to the application in which the gel will be used. Dried gels in various ways are used in industries such as surface coating, building insulation, and the production of special clothing. It is worth mentioning that, by grinding the gel by special mills, it is possible to achieve nanoparticles.

ON THE ELECTRONIC AND GEOMETRIC STRUCTURE OF GRAPHENE OXIDE IN THE FRAMEWORK OF THE HOFFMAN AND RESS MODELS

For the first time, the geometric and electronic structure of graphene oxide was calculated within the framework of the Hoffman and Ress models by the quantum-chemical method MNDO. Optimized structures of this compound are obtained. The acidic strength (pKa = 28 and pKa = 14) was theoretically estimated in the Hoffman and Ress model, respectively.

Chemical synthesis of nanopowder Nd2Fe14BаSiO2 of the nucleus-shell type

Nanoparticles of the alloy with the composition Nd-Fe-B were formed by the chemical method of co-precipitation reduction using a reducing agent sodium borohydride. The nanoparticle size was 35–95 nm. The silica coating was applied after stabilizing the nanoparticles with APTMS. The core of Nd-Fe-B alloy nanoparticles covered with a SiO2 shell, Nd2Fe14BаSiO2, the particle size was 35–125 nm with a shell width of 8–15 nm.

Synthesis and Study the Properties of a Solar Cell of Gold Nanoparticles Prepared in a Simple Chemical Way

The aim of this study is to prepare gold nanoparticles by a simple chemical method at a temperature of 70°C. The solution was dried on glass basest by Casting method, the rate of five drops per sample At a temperature 100 C. Then the structural and optical properties have been confirmed by X-ray diffraction, scanning electron microscopy (SEM) and Transmission Electron microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and spectrum.