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1
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Catalytic Supramolecular Photochirogenesis

100%
Yan Z., Wu W., Yang C., Inoue Y.
Supramolecular Catalysis
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2015
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vol. 2
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issue 1
EN
Supramolecular photochirogenesis is a new strategy for circumventing the inherent difficulties encountered in conventional photochirogenesis, i.e. the interactions associated with geometrically less-defined, short-lived excited states, by confining a prochiral substrate(s) in a chiral supramolecular environment(s) prior to photoexcitation. This rather simple, but very successful, strategy has been applied to a variety of chiral photoreactions. However, a stoichiometric, or even excess amount of supramolecular host is often needed to ensure full complexation of the substrate, and achieve the optimum stereochemical outcome. This apparent drawback has recently been removed by introducing a sensitizing moiety to the supramolecular host, or by bathochromically shifting the absorption band of substrate through Lewis acid, or charge-transfer complexation. Recent progress in catalytic supramolecular photochirogenesis will be reviewed.
2
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Ionic liquid-functionalized SBA-15 mesoporous material: efficient heterogeneous catalyst in versatile organic reactions

100%
Xu L.-W., Yang M.-S., Jiang J.-X., Qiu H.-Y., Lai G.-Q.
Open Chemistry
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2007
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vol. 5
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issue 4
1073-1083
EN
Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst in these reactions could be carried out and the catalyst used at least five times without significant loss in activity. [...]
3
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Modelling of regeneration and filtration mechanism in diesel particulate filter for development of composite regeneration emission control system

89%
Kurien C., Srivastava A. K., Naudin J., Kurien C., Srivastava A. K., Naudin J.
Archive of Mechanical Engineering
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2018
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vol. 65
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issue 2
4
Content available remote

Catalytic Activity of Gold and Silver Nanoparticles Supported on Zinc Oxide

88%
Yesmurzayeva N. N., Nurakhmetova Z. A., Tatykhanova G. S., Selenova B. S., Kudaibergenov S. E.
Supramolecular Catalysis
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2015
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vol. 2
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issue 1
EN
Gold (AuNPs) and silver (AgNPs) nanoparticles have been prepared by “one-pot” synthetic method in the presence of poly(N-vinylpyrrolidone) (PVP). Absorption spectra, size, morphology, and structure of AuNPs and AgNPs were studied by UV-Vis spectroscopy, DLS, SEM, and TEM. According to DLS measurements the average sizes of metal nanoparticles stabilized by PVP in aqueous solution are varied from 10 to 25 nm for AuNPs and from 6.5 to 44 nm for AgNPs. The impregnation method is used to support AuNPs and AgNPs on the surface of ZnO. The amount of AuNPs and AgNPs immobilized on the surface of ZnO does not exceed 0.2 wt.%. The catalytic activity of AuNPs and AgNPs supported on the surface of ZnO was evaluated with respect to decomposition of hydrogen peroxide. The optimal conditions for H2O2 decomposition were found to be dependent on of the amount of the catalyst, concentration of substrate, molecular weight of PVP, and temperature. The activation energy of H2O2 decomposition is equal to 44.1 kJ×mol-1. The decomposition of H2O2 in the presence of AuNPs and AgNPs supported on ZnO surface is discussed in the context of supramolecular catalysis mimicking catalase-like behavior. The recyclability of AuNPs supported on ZnO surface was tested.
5
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A Mechanistic Model of a Passive Autocatalytic Hydrogen Recombiner

88%
Rożeń A.
Chemical and Process Engineering
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2015
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vol. 36
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issue 1
3-19
EN
: A passive autocatalytic hydrogen recombiner (PAR) is a self-starting device, without operator action or external power input, installed in nuclear power plants to remove hydrogen from the containment building of a nuclear reactor. A new mechanistic model of PAR has been presented and validated by experimental data and results of Computational Fluid Dynamics (CFD) simulations. The model allows to quickly and accurately predict gas temperature and composition, catalyst temperature and hydrogen recombination rate. It is assumed in the model that an exothermic recombination reaction of hydrogen and oxygen proceeds at the catalyst surface only, while processes of heat and mass transport occur by assisted natural and forced convection in non-isothermal and laminar gas flow conditions in vertical channels between catalyst plates. The model accounts for heat radiation from a hot catalyst surface and has no adjustable parameters. It can be combined with an equation of chimney draft and become a useful engineering tool for selection and optimisation of catalytic recombiner geometry.
6
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Cold plasma in the nanotechnology of catalysts

88%
Tyczkowski J., Kapica R.
Polish Journal of Chemical Technology
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2007
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vol. 9
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issue 1
36-42
EN
In the paper the preparation of catalysts with the use of cold plasmas is discussed. A special attention is focused on nanocatalysts. In general, there are three main trends in this field: (1) plasma enhanced preparation of "classical" catalysts, (2) plasma sputtering of catalytically active compounds, especially metal and metal oxide nanoparticles, and (3) plasma-enhanced metal-organic chemical vapor deposition (PEMOCVD) of very thin metal and metal oxide films with specific nanostructure. It is shown that the cold plasma techniques are very effective methods for designing the nanocatalysts with distinct and tunable chemical activity, specificity and selectivity. Finally, our preliminary investigations concerning CoOX catalytic films fabricated by the PEMOCVD method are presented.
7
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Theoretical model explaining the relationship between the molecular mass and the activation energy of the enzyme revealed by a large-scale analysis of bioinformatics data

88%
Pawlowski P. H., Zielenkiewicz P.
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2013
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vol. 60
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issue 2
239-247
EN
A general dependence of the enzyme catalytic rate on its mass was revealed when a statistical analysis of 17065 records from the EMP database was performed. The estimated activation energy of the catalytic process decreases asymptotically with the enzyme molecular mass increase. The proposed theoretical model postulates the existence of an intermediate complex of the enzyme and the departing product. It allows for the explanation of the discovered mass-energy relationship, as an effect of the global enzyme-product interactions during complex dissociation. Fitted parameters of the model seem to be in agreement with those widely accepted for the van der Waals energy of molecular interactions. Their values also agree with the picture of the hydrogen bonding in the catalytic process and suggest that surface walk can be the favorable way of the product departure.
8
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Exploring the potential of 3-nitrobenzaldehyde thiosemicarbazone: versatile ligand for coordination complexes and its multidisciplinary applications – a review

75%
Senthilkumar V., Nisha S., Saravanan M.
World News of Natural Sciences
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2023
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vol. 50
98-109
EN
3-Nitrobenzaldehyde thiosemicarbazone demonstrates a versatile nature in forming coordination complexes with various metals. These complexes have garnered significant interest in fields such as coordination chemistry, medicinal chemistry, catalysis, and material science. The ligand's nitrogen and sulfur atoms serve as potential coordination sites, allowing for the formation of diverse complexes with different metals. These complexes exhibit bioactive properties in medicinal chemistry, serve as catalysts in catalytic processes, and contribute to the development of novel materials with tailored functionalities in material science. The exploration of 3-nitrobenzaldehyde thiosemicarbazone complexes with multiple metals offers promising avenues for research and application in various scientific disciplines.
9
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Spectroscopic observation of helium-ion- and hydrogen-catalyzed hydrino transitions

75%
Mills R., Lu Y., Akhtar K.
Open Physics
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2010
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vol. 8
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issue 3
318-339
EN
Four predictions of Mills’ Grand Unified Theory of Classical Physics (GUTCP) regarding atomic hydrogen undergoing a catalytic reaction with certain atomized elements and ions which resonantly, nonradiatively accept integer multiples of the potential energy of atomic hydrogen, m · 27.2 eV wherein m is an integer, have been confirmed experimentally. Specifically, a catalyst comprises a chemical or physical process with an enthalpy change equal to an integer multiple m of the potential energy of atomic hydrogen, 27.2 eV. For He+ m = 2, due to its ionization reaction to He2+, and two H atoms formed from H2 by collision with a third, hot H can also act as a catalyst with m = 2 for this third H. The product is H(1/p), fractional Rydberg states of atomic hydrogen called “hydrino atoms” wherein n = 1/2, 1/3, 1/4, …, 1/p(p≤137 is an integer) replaces the well-known parameter n = integer in the Rydberg equation for hydrogen excited states. The predictions for the hydrino reaction of (1) pumping of the catalyst excited states, (2) characteristic EUV continuum radiation, (3) fast H, and (4) hydrino products were observed in multiple catalyst-hydrogen plasma systems.
10
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A Mechanistic Model of a Passive Autocatalytic Hydrogen Recombiner

75%
Rożeń A.
Chemical and Process Engineering
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2015
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issue 1
11
Content available remote

ToF-SIMS studies of the surface of Pd/ZrO2-TiO2catalyst used in the hydrodechlorination process

75%
Grams J., Góralski J., Kleczewska J., Szczepaniak B., Paryjczak T.
Polish Journal of Chemical Technology
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2007
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vol. 9
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issue 3
81-85
EN
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used in order to obtain the information about the surface composition of Pd/ZrO2-TiO2 catalyst and to estimate the changes in the concentration of particular components on its surface during the hydrodechlorination of CCl4. The results demonstrated that the hydrodechlorination process led to the increase in the concentration of chlorine and the drop in the amount of surface accessible palladium, while the quantity of Pd-Cl bounds did not change considerably. It suggested that the presence of ZrO2 protected the surface of the studied catalyst against the formation of PdCl2.
12
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SCREENING OF THE CATALYTIC ACTIVITY OF Pd0 AND Pd2+- SUPPORTED ON CHITOSAN BEADS AND CRYOGELS

75%
Pestov A., Mekhaev A., Privar Y., Prokuda N., Modin E., Bratskaya S.
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EN
Here, we report the results of screening of the catalytic activity of Pd-containing chitosan beads and cryogels in the cross-coupling reaction, hydrogenation of alkenes, nitro-, and carbonyl compounds and the hydrodechlorination of chlorophenols. Pd0-containing chitosan beads and cryogels show moderate catalytic activity in the reduction of alkenes and nitroaromatics. The conversion of nitroaromatics decreases for substrates with electron-withdrawing substituents, while the conversion of alkenes increases with the activation of carbon-carbon double bonds. For several substrates, a significant difference in kinetics and conversion degrees was observed for Pd nanoparticles supported on chitosan beads and cryogels. It was found that conversion in the hydrodechlorination reaction depends on substrate structure, being higher for substrates containing substituents with a positive mesomeric effect. Pd2+-chitosan catalysts showed high catalytic activity in cross-coupling (Heck reaction) offering the following advantages over known catalytic systems: lower reaction temperature, the selective functionalisation of C-I bonds, and the possibility to perform reactions with iodobenzene without base addition.
13
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A study of ruthenium-based catalysts used in homogeneous transfer hydrogenation of acetophenone

75%
Mikołajczyk F., Kamiński K., Mikołajczyk F., Kamiński K.
Chemical and Process Engineering
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2019
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vol. 40
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issue 2
14
Content available remote

Short Peptides in Minimalistic Biocatalyst Design

63%
Duncan K. L., Ulijn R. V.
Biocatalysis
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2014
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vol. 1
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issue 1
EN
We review recent developments in the use of short peptides in the design of minimalistic biocatalysts focusing on ester hydrolysis. A number of designed peptide nanostructures are shown to have (modest) catalytic activity. Five features are discussed and illustrated by literature examples, including primary peptide sequence, nanosurfaces/scaffolds, binding pockets, multivalency and the presence of metal ions. Some of these are derived from natural enzymes, but others, such as multivalency of active sites on designed nanofibers, may give rise to new features not found in natural enzymes. Remarkably, it is shown that each of these design features give rise to similar rate enhancements in ester hydrolysis. Overall, there has been significant progress in the development of fundamental understanding of the factors that influence binding and activity in recent years, holding promise for increasingly rational design of peptide based biocatalysts.
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