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171.
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173.
Dr. Igor Krivtsov Dr. Dariusz Mitoraj Christiane Adler Dr. Marina Ilkaeva Dr. Mariana Sardo Dr. Luís Mafra Christof Neumann Prof. Andrey Turchanin Chunyu Li Prof. Benjamin Dietzek Robert Leiter Dr. Johannes Biskupek Prof. Ute Kaiser Changbin Im Björn Kirchhoff Prof. Timo Jacob Prof. Radim Beranek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):495-503
Heptazine-based polymeric carbon nitrides (PCN) are promising photocatalysts for light-driven redox transformations. However, their activity is hampered by low surface area resulting in low concentration of accessible active sites. Herein, we report a bottom-up preparation of PCN nanoparticles with a narrow size distribution (ca. 10±3 nm), which are fully soluble in water showing no gelation or precipitation over several months. They allow photocatalysis to be carried out under quasi-homogeneous conditions. The superior performance of water-soluble PCN, compared to conventional solid PCN, is shown in photocatalytic H2O2 production via reduction of oxygen accompanied by highly selective photooxidation of 4-methoxybenzyl alcohol and benzyl alcohol or lignocellulose-derived feedstock (ethanol, glycerol, glucose). The dissolved photocatalyst can be easily recovered and re-dissolved by simple modulation of the ionic strength of the medium, without any loss of activity and selectivity. 相似文献
174.
Dariusz Wyrzykowski Michał Wera Artur Sikorski Dagmara Jacewicz Lech Chmurzyński 《Central European Journal of Chemistry》2011,9(6):1096-1101
The crystal structure of 2-methylpyridinium tetrachloroferrate(III) was determined. The iron cation is tetracoordinated by
chloride anions, and it adopts a slightly distorted tetrahedral coordination with three angles smaller, two almost equal and
one larger than the tetrahedral. The compound is isostructural with its 3-, and 4-methylpyridinium analogues. The thermal
properties of 2-, 3- and 4-methylpyridinium tetrachloroferrates(III) have been studied using TG and DSC techniques. The compounds
exhibit a high stability in the melt.
相似文献
175.
Ma J Ma YC Cai C Wang D Hou FF Luo M Lu S Gorecki DC Patel AV Chen A Jin P 《Natural product communications》2011,6(5):639-643
Echinacea angustifolia and E. purpurea are commonly used in North America for their anti-bacterial effects. Flos Lonicerae, Radix Scutellaria and Fructus Forsythiae are traditional Chinese medicinal herbs commonly used for the treatment of complaints such as pneumonia, acute upper respiratory tract infection, and acute bronchitis. A reproducible, simple, and reliable rapid resolution liquid chromatographic (RRLC) method has been developed to analyze extracts of products formulated containing E. angustifolia, E. purpurea, Flos Lonicerae, Radix Scutellariae and Fructus Forsythiae simultaneously in one run in less than 6 minutes. The method uses a C18-HST column, a mobile phase consisting of 0.1% aqueous phosphoric acid solution and acetonitrile, and UV detection at 327 nm and 229 nm. A stability test was performed that revealed that chlorogenic acid is more stable in acidic pH, and hence it is best to keep the extract of E. augustifolia, E. purpurea, Flos Lonicerae, Radix Scutellariae and Fructus Forsythiae in mild acidic conditions at approximately pH 5. 相似文献
176.
Water and salts strongly influence the durability of porous materials. One of the most adverse phenomena which is related
to the salt and moisture presence in the pore system of building materials is salt crystallization. The process is associated
with the supersaturation ratio. The salt phase change kinetics is taken into account during the modeling of coupled moisture,
salt, and heat transport. To solve the set of governing, differential equations the finite element and the finite difference
methods are used. Three different rate laws are assumed in modeling the salt phase change. The drying, cooling, and warming
of the cement mortar sample, during which the salt phase change occurs, have been simulated using the developed software.
The changes of salt concentration in the pore solution and the amount of precipitated salt due to variation of boundary conditions
are presented and discussed. The results obtained in the numerical simulation assuming the first, second, and fourth order
rate low indicate that the higher order of the rate law the longer time delay between the change of boundary conditions and
the salt precipitation. Such an analysis might be very useful during the determination of the material parameters by solving
the inverse problem. 相似文献
177.
Dariusz Gawin Francesco Pesavento Bernhard A. Schrefler 《International Journal of Solids and Structures》2011,48(13):1927-1944
The paper deals with modelling of hygro-thermal performance and thermo-chemical degradation of concrete exposed to high temperature. Several possible simplifications in modelling of heat and mass transport phenomena in heated concrete are considered and their effect on the results of numerical simulations is analyzed.A mathematical model of concrete at high temperature, already extensively validated with respect to experiments, is used as the reference model. It is based on mechanics of multiphase porous media and considers all important couplings and material nonlinearities, as well as different properties of water above the critical point of water, i.e. 647.3 K (374.15 °C).In this part of the paper, first physical phenomena, as well as heat and mass flux and sources in a concrete element are studied, both during slow and fast heating process, to examine the relative importance of different flux components. Then, the mathematical model of concrete at high temperature, developed by Authors in the last 10 years, is briefly presented and for the first time all the constitutive relationships of the model are summarized and discussed in detail. Finally, the method of numerical solution of the model equations is thoroughly presented.In the companion paper (part II) a brief literature review of the existing mathematical models of concrete at high temperature and a summary of their main features and physical assumptions will be presented. Then, extensive numerical studies will be performed with several simplified models, neglecting chosen physical phenomenon or flux components, to evaluate the difference between the results obtained with the simplified models and with the reference model. The study will concern hygric, thermal and degradation performance of 1-D and 2-D axisymmetric concrete elements during fast and slow heating. The analysis will allow us to indicate which simplifications in modeling of concrete at high temperature are practically and physically possible, without generating excessive errors with respect to the full reference model. 相似文献
178.
Dariusz Plewczynski Michał Łażniewski Marcin Von Grotthuss Leszek Rychlewski Krzysztof Ginalski 《Journal of computational chemistry》2011,32(4):568-581
Molecular recognition plays a fundamental role in all biological processes, and that is why great efforts have been made to understand and predict protein–ligand interactions. Finding a molecule that can potentially bind to a target protein is particularly essential in drug discovery and still remains an expensive and time‐consuming task. In silico, tools are frequently used to screen molecular libraries to identify new lead compounds, and if protein structure is known, various protein–ligand docking programs can be used. The aim of docking procedure is to predict correct poses of ligand in the binding site of the protein as well as to score them according to the strength of interaction in a reasonable time frame. The purpose of our studies was to present the novel consensus approach to predict both protein–ligand complex structure and its corresponding binding affinity. Our method used as the input the results from seven docking programs (Surflex, LigandFit, Glide, GOLD, FlexX, eHiTS, and AutoDock) that are widely used for docking of ligands. We evaluated it on the extensive benchmark dataset of 1300 protein–ligands pairs from refined PDBbind database for which the structural and affinity data was available. We compared independently its ability of proper scoring and posing to the previously proposed methods. In most cases, our method is able to dock properly approximately 20% of pairs more than docking methods on average, and over 10% of pairs more than the best single program. The RMSD value of the predicted complex conformation versus its native one is reduced by a factor of 0.5 Å. Finally, we were able to increase the Pearson correlation of the predicted binding affinity in comparison with the experimental value up to 0.5. © 2010 Wiley Periodicals, Inc. J Comput Chem 32: 568–581, 2011 相似文献
179.
Dariusz Plewczynski Rafał Augustyniak Krzysztof Ginalski 《Journal of computational chemistry》2011,32(4):742-755
Docking is one of the most commonly used techniques in drug design. It is used for both identifying correct poses of a ligand in the binding site of a protein as well as for the estimation of the strength of protein–ligand interaction. Because millions of compounds must be screened, before a suitable target for biological testing can be identified, all calculations should be done in a reasonable time frame. Thus, all programs currently in use exploit empirically based algorithms, avoiding systematic search of the conformational space. Similarly, the scoring is done using simple equations, which makes it possible to speed up the entire process. Therefore, docking results have to be verified by subsequent in vitro studies. The purpose of our work was to evaluate seven popular docking programs (Surflex, LigandFit, Glide, GOLD, FlexX, eHiTS, and AutoDock) on the extensive dataset composed of 1300 protein–ligands complexes from PDBbind 2007 database, where experimentally measured binding affinity values were also available. We compared independently the ability of proper posing [according to Root mean square deviation (or Root mean square distance) of predicted conformations versus the corresponding native one] and scoring (by calculating the correlation between docking score and ligand binding strength). To our knowledge, it is the first large‐scale docking evaluation that covers both aspects of docking programs, that is, predicting ligand conformation and calculating the strength of its binding. More than 1000 protein–ligand pairs cover a wide range of different protein families and inhibitor classes. Our results clearly showed that the ligand binding conformation could be identified in most cases by using the existing software, yet we still observed the lack of universal scoring function for all types of molecules and protein families. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
180.
The β-blockers are important drugs and decades of clinical experience proved their high medical status. However, to the best of our knowledge, there is no complete assignment of (1)H and (13)C NMR resonances of popular representatives: acebutolol, alpenolol, pindolol, timolol and propranolol and the published NMR data on carvedilol and atenolol are incorrect. Therefore, (1)H and (13)C NMR spectroscopy was applied for the characterization of a series of β-adrenolytics: carvedilol (1), pindolol (2), alprenolol (3), acebutolol (4), atenolol (5), propranolol (6) and timolol (7). Two-dimensional NMR experiments (COSY, HMQC, HMBC, NOESY) allowed the unequivocal assignment of (1)H and (13)C spectra for solution (DMSO-d(6) ). Salts and bases can be easily distinguished based on (13)C chemical shifts which are within 65.0-65.5 ppm (OC2) and 46.9-47.0 (NC3) for hydrochlorides and larger, ca. 68.4 ppm (OC2) and 50.3-52.6 (NC3) for bases. NMR data of 1-7 should be included in pharmacopoeias. 相似文献