نتایج جستجو برای: catalytic effects
تعداد نتایج: 1616125 فیلتر نتایج به سال:
Since the discovery of self-cleavage and ligation activity of the group I intron, the expansion of research interest in catalytic nucleic acids has provided a valuable nonprotein resource for manipulating biomolecules. Although a multitude of reactions can be enhanced by this class of catalyst, including trans-splicing activity of the group I intron (which could be applied to gene correction), ...
three high-silica mordenite zeolites differing in sio440, ratio were prepared by direct synthesis without using any template. the products si02/a120, ratio is influenced by the starting gel composition. this ratio is increased upon ion-exchange with nh,cl and subsequent calcination to prepare protonic mordenite. the protonic mordenites with si02/a1203ra tios of 14.6,29.2 and 34.6 were character...
nano-graphene oxide was synthesized by the oxidation of graphite powders. the structural nature of the nano-graphene oxide was characterized by a variety of techniques including xrd, tem, ft-ir and uv/vis. the functional groups on its basal planes and edges of nano-grahene oxide play important role in catalytic activity. the catalytic activity of nano-graphene oxide was investigated on crossed-...
the determination of the optimal distribution of the catalytic activity profile, whichmaximizes the catalytic effectiveness, in created unsteady state conditions, is analyzed andtreated numerically for the case of a simple reaction. it was proven that the modulation, of thetemperature and the reactant concentration of the external bulk fluid, leads to a considerableincrease of the catalytic eff...
in the present work, impact of lewis acid (la) catalysts bf3, bcl3, and bbr3 on the kinetics andregioselectivity of 1,3-dipolar cycloaddition (1,3-dc) reaction between azidobenzene and acroleinwas theoretically studied using b3lyp/6-31g* level. our results indicate while the uncatalyzed 1,3-dc reaction under investigation takes place via a non-polar, non-regioselective, and lowasynchronous proc...
four different alkaline earth metal oxides i.e. mgo, cao, sro and bao were used as heterogeneous catalysts for biodiesel production from palm oil. effects of critical process variables i.e. reaction time, methanol to oil ratio and temperature were investigated. the results were then fitted to a historical design to study the analysis of variance (anova), to characterize interactions between var...
In this paper we present an overview of recent work on lattice and measure-valued models of catalytic reactions and in particular catalytic branching systems. The main phenomena exhibited by nearly critical branching systems are dimension-dependent clumping in small and large space and time scales. Special emphasis is given to the e ects which occur when the catalyst is highly clumped and in pa...
Synthesis of adipic acid by catalytic oxidation of cyclohexanone with 30% hydrogen peroxide in the presence of sodium tungstate catalyst can be well performed under reflux temperature. The adipic acid isolated yield reaches to 82.1%, and the purity of the product is also very high. The catalytic oxidation reaction takes place without any organic solvent and phase-transfer agent. The effects ove...
Quaternary ammonium geminal Brønsted acid ionic liquids (GBAILs) based on zwitterionic 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]ethane (where the carbon number of the alkyl chain is 4, 8, 10, 12, 14, 16, or 18) and p-toluenesulfonic acid monohydrate were synthesized. The catalytic ionic liquids were applied in three-component Mannich reactions with an aldehyde, ketone, and amine at 25 °...
In the 15-mer catalytic core of 10-23 DNAzyme, each residue contributes to the catalytic conformation differently. Here, the critically conserved T4 and the least conserved T8 were modified on their 5-position with hydroxyl, imidazolyl, and amino groups with a hydrogen-bonding ability. These external functional groups induced new interactions within the catalytic core, resulting in both negativ...
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