Search results for "Chemical reaction"

CO Oxidation on Cationic Gold Clusters: A Theoretical Study

2008

Aiming at understanding the elementary steps governing the oxidation of CO catalyzed by dispersed or supported gold nanoclusters, the reactivity of molecular species, such as O2 and CO, on neutral and positively charged Au13 clusters have been studied using a DFT approach. Two CO oxidation mechanisms have been simulated, involving respectively the adsorption of CO and O2 on adjacent catalytic sites (two-sites mechanism) and the competitive interaction of the reactants on the same site (single-site mechanism). It is demonstrated that in the former scheme a definite interaction of CO and O2 with both the charged and neutral cluster is effective, but that a chemical reaction between the adsorb…

Nonheme Fe(IV) Oxo Complexes of Two New Pentadentate Ligands and Their Hydrogen-Atom and Oxygen-Atom Transfer Reactions.

2015

Two new pentadentate {N5} donor ligands based on the N4Py (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine) framework have been synthesized, viz. [N-(1-methyl-2-benzimidazolyl)methyl-N-(2-pyridyl)methyl-N-(bis-2-pyridyl methyl)amine] (L1) and [N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine] (L2), where one or two pyridyl arms of N4Py have been replaced by corresponding (N-methyl)benzimidazolyl-containing arms. The complexes [FeII(CH3CN)(L)]2+ (L = L1 (1); L2 (2)) were synthesized, and reaction of these ferrous complexes with iodosylbenzene led to the formation of the ferryl complexes [FeIV(O)(L)]2+ (L = L1 (3); L2 (4)), which were characterized by UV–vis spe…

The desert gerbil Psammomys obesus as a model for metformin-sensitive nutritional type 2 diabetes to protect hepatocellular metabolic damage: Impact …

2017

Introduction While metformin (MET) is the most widely prescribed antidiabetic drug worldwide, its beneficial effects in Psammomys obesus (P. obesus), a rodent model that mimics most of the metabolic features of human diabetes, have not been explored thoroughly. Here, we sought to investigate whether MET might improve insulin sensitivity, glucose homeostasis, lipid profile as well as cellular redox and energy balance in P. obesus maintained on a high energy diet (HED). Materials and methods P. obesus gerbils were randomly assigned to receive either a natural diet (ND) consisting of halophytic plants (control group) or a HED (diabetic group) for a period of 24 weeks. MET (50 mg/kg per os) was…

Role of HDL function and LDL atherogenicity on cardiovascular risk: a comprehensive examination

2019

[Background] High-density lipoprotein (HDL) functionality and low-density lipoprotein (LDL) atherogenic traits can describe the role of both particles on cardiovascular diseases more accurately than HDL- or LDL-cholesterol levels. However, it is unclear how these lipoprotein properties are particularly affected by different cardiovascular risk factors.

Chemically Fueled Block Copolymer Self‐Assembly into Transient Nanoreactors**

2021

In chemically fueled supramolecular materials, molecular self-assembly is coupled to a fuel-driven chemical reaction cycle. The fuel-dependence makes the material dynamic and endows it with exciting properties like adaptivity and autonomy. In contrast to the large work on the self-assembly of small molecules, we herein designed a diblock copolymer, which self assembles into transient micelles when coupled to a fuel-driven chemical reaction cycle. Moreover, we used these transient block copolymer micelles to locally increase the concentration of hydrophobic reagents and thereby function as a transient nanoreactor.

Luminescence and FTIR Spectroscopy of ZnO Nanocrystals

2006

Time-resolved luminescence and Furje Transformation Infrared (FTIR) absorption spectroscopy for ZnO nanocrystals prepared under different chemical reactions using microwave driven hydrothermal process was studied. OH- group stretching vibration frequency is considerably different in nanocrystals studied and in single ZnO crystal. It is shown that fractions of chemicals used in synthesis process could be found in nanopowders. Luminescence at ~2.0 eV (due to defect states in ZnO crystals and nanopowders) was suppressed in nanopowders obtained by urea method.

Radiowave emission accompanying the phase changes and chemical reactions in condensed phases

1994

RANDOM SEQUENTIAL ADSORPTION ON A LINEAR LATTICE: EFFECT OF DIFFUSIONAL RELAXATION

1992

In this paper, the authors offer phenomenological arguments, supported by numerical Monte Carlo data, suggesting that the asymptotic large-time behavior of the coverage in the 1D lattice deposition of k-mers with k {gt} 3, accompanied by k-mer diffusion, is governed by the same mean-field dynamics as the lattice chemical reaction kA {yields} inert. The latter reaction is considered to occur with partial probability. The coverage in the deposition process approaches full saturation for any nonzero diffusion rate, and the void fraction decreases according to the power-law t{sup {minus}1/(k{minus}1)}.

A Simple “Plastic Bag” Technique for Visible Spectra of Solid Metal Complexes

1979

The techniques commonly used to study the visible spectra of transition metal complexes in the solid state involve diffuse reflectance from the powdered sample or transmission through a mull of the compound in mineral oil on filter paper. Pressed KBr (for anhydrous compounds) and AgCl (for compounds containing water or other highly polar ligands) disk techniques have been used even for low temperature spectra. All of the transmission techniques mentioned are based on mixing the sample with another compound which may induce changes in the compound under study via chemical reactions. Air- and water-sensitive complexes also need special care. These interferences may be reduced by the use of th…

H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

2016

<p class="1Body">Effects of Ru and Re promoters on Co-CoO<sub>x </sub>catalysts supported on γ-Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub> and SiC were investigated to improve the understanding of the role of promoters of the active phase of Co-CoO<sub>x</sub>-Ru and Co-CoO<sub>x</sub>-Re. The influence of promoter addition on the composition and activity of the catalysts was characterized by several methods, such as H<sub>2</sub>-TPR, XPS, chemisorption and TEM. Furthermore, the role of support and metal-support interaction was especially studied and different support materials were compared.</p&g…