Search results for " surface"
showing 10 items of 2838 documents
X-Ray structure, Hirshfeld analysis and DFT studies of two new hits of triazolyl-indole bearing alkylsulfanyl moieties
2021
Two new hits of triazolyl-indole containing two different alkylsulfanyl analogues named tert-butyl 2-((4-amino-5-(1H-indol-2-yl)-4H-1,2,4-triazol-3-yl)thio)acetate 2, and ethyl 2-((4-amino-5-(1H-indol-2-yl)-4H-1,2,4-triazol-3-yl)thio)acetate 3 were synthesized via reaction of 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione 1 with tert-butyl bromoacetate and ethyl chloroacetate in the presence of base (Et3N). The molecular structure of 2, and 3 was confirmed by single-crystal X-ray diffraction and 1H/13C- NMR spectroscopic techniques. In compound 2, the molecular packing depends on significant O...H (9.3%), N...H (12.4%) and S...H (3.1%) as well as relatively weak C...H (14.1%), S...C (…
Asymmetric Synthesis of Chiral Bimetallic [Ag28Cu12(SR)24]4– Nanoclusters via Ion Pairing
2016
In this work, a facile ion-pairing strategy for asymmetric synthesis of optically active negatively charged chiral metal nanoparticles using chiral ammonium cations is demonstrated. A new thiolated chiral three-concentric-shell cluster, [Ag28Cu12(SR)24]4–, was first synthesized as a racemic mixture and characterized by single-crystal X-ray structure determination. Mass spectrometric measurements revealed relatively strong ion-pairing interactions between the anionic nanocluster and ammonium cations. Inspired by this observation, the as-prepared racemic mixture was separated into enantiomers by employing chiral quaternary ammonium salts as chiral resolution agents. Subsequently, direct asymm…
Changes in surface stress, morphology and chemical composition of silica and silicon nitride surfaces during the etching by gaseous HF acid
2007
International audience; HF acid attack of SiO2 and Si3N4 substrates is analyzed to improve the sensitivity of a sensor based on inicrocantilever. Ex situ analysis of the etching using XPS, SIMS and AFM show significant changes in the anisotropy and the rate of the etching of the oxides on SiO2 and Si3N4 surface. Those differences influence the kinetic evolution of the plastic bending deflection of the cantilever coated with SiO2 and Si3N4 layer, respectively. The linear dependence between the HF concentration and the Si3N4 cantilever bending corresponds to a deep attack of the layer whereas the nonlinear behavior observed for SiO2 layer can be explained by a combination of deep and lateral …
Coupling two radar backscattering models to assess soil roughness and surface water content at farm scale
2013
Remote sensing techniques are useful for agro-hydrological monitoring at the farm scale because the availability of spatially and temporally distributed data improves agricultural models for irrigation and crop yield optimization under water scarcity conditions. This research focuses on the surface water content retrieval using active microwave data. Two semi-empirical models were chosen as these showed the best performances in simulating cross and co-polarized backscatter. Thus, these models were coupled to obtain reliable assessments of both soil water content and soil roughness. The use of the coupled model enables one to avoid using roughness measured in situ. Remote sensing images and …
Nitrogen Adsorption on Graphene Sponges Synthesized by Annealing a Mixture of Nickel and Carbon Powders
2017
The present research has been supported by the National Research Programme for 2014–2017 “Multifunctional Materials and Composites, Photonics and Nanotechnologies”.
Yeast Killer Toxin-Like Candidacidal Ab6 Antibodies Elicited through the Manipulation of the Idiotypic Cascade
2014
A mouse anti-anti-anti-idiotypic (Id) IgM monoclonal antibody (mAb K20, Ab4), functionally mimicking a Wyckerhamomyces anomalus (Pichia anomala) killer toxin (KT) characterized by fungicidal activity against yeasts presenting specific cell wall receptors (KTR) mainly constituted by β-1,3-glucan, was produced from animals presenting anti-KT Abs (Ab3) following immunization with a rat IgM anti-Id KT-like mAb (mAb K10, Ab2). MAb K10 was produced by immunization with a KT-neutralizing mAb (mAb KT4, Ab1) bearing the internal image of KTR. MAb K20, likewise mAb K10, proved to be fungicidal in vitro against KT-sensitive Candida albicans cells, an activity neutralized by mAb KT4, and was capable of…
Preorganization and reorganization as related factors in enzyme catalysis: the chorismate mutase case.
2003
In this paper a deeper insight into the chorismate-to prephenate-rearrangement, catalyzed by Bacillus subtilis chorismate mutase, is provided by means of a combination of statistical quantum mechanics/molecular mechanics simulation methods and hybrid potential energy surface exploration techniques. The main aim of this work is to present an estimation of the preorganization and reorganization terms of the enzyme catalytic rate enhancement. To analyze the first of these, we have studied different conformational equilibria of chorismate in aqueous solution and in the enzyme active site. Our conclusion is that chorismate mutase preferentially binds the reactive conformer of the substrate--that…
The coralline red alga Lithophyllum kotschyanum f. affine as proxy of climate variability in the Yemen coast, Gulf of Aden (NW Indian Ocean)
2014
Abstract Recent investigations have shown the potential of red coralline algae as paleoclimatic archive. A previously unexplored subfamily of coralline algae, the Lithophylloideae, was investigated from the Gulf of Aden (Balhaf, Yemen). Seasonal changes in Mg/Ca, Li/Ca and Ba/Ca composition of Lithophyllum kotschyanum f. affine were investigated by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). For the first time in coralline algae, the Li/Ca composition was analyzed and showed a highly significant and positive correlation with Mg/Ca and SST. Monthly algal Mg/Ca and Li/Ca variations indicate a positive correlation with sea surface temperature (SST), and sea surface…
Sclerochronology and geochemical variation in limpet shells (Patella vulgata): A new archive to reconstruct coastal sea surface temperature
2007
[1] Climate archives contained in shells of the European limpet, Patella vulgata, accumulated in archaeological deposits can potentially provide much needed information about Holocene environmental change in midlatitude coastal areas. Before reconstructing climate information preserved in these zooarchaeological records, we studied the controls on oxygen and carbon isotope ratios (δ18O and δ13C, respectively) in modern specimens. We tested the hypothesis that P. vulgata precipitates its shell in isotopic equilibrium with the ambient water by comparing δ18OSHELL with predicted values. Predicted δ18OSHELL was constructed using observed sea surface temperature (SST) records and the equilibrium…
Neural activities of IL-6-type cytokines often depend on soluble cytokine receptors
1999
Cytokines of the interleukin-6 (IL-6) family participate in regulatory and inflammatory processes within the nervous system. IL-6, ciliary neurotrophic factor (CNTF) and IL-11 act via specific membrane receptors which, together with their ligands, associate with signal-transducing receptor subunits thereby initiating cytoplasmic signalling. Cells which only express signal-transducing receptor subunits but no ligand binding subunits for IL-6, CNTF and IL-11 are refractory to these cytokines. An unusual feature of the IL-6 cytokine family is that the soluble forms of the ligand binding receptor subunits generated by one cell type in complex with their ligands can directly stimulate the signal…