نتایج جستجو برای: chemical exchange
تعداد نتایج: 559370 فیلتر نتایج به سال:
Glassy materials provide a unique set of properties, such as transparency, high hardness and good chemical durability, forming ability, low cost production and the possibility of recycling. They are therefore used in a wide range of applications, e.g. windows, containers, displays, thermal insulation, optical lenses, data transport, or, e.g. as bioactive materials. The fact that glass is a rela...
Chemical exchange saturation transfer (CEST) imaging is a relatively new magnetic resonance imaging contrast approach in which exogenous or endogenous compounds containing either exchangeable protons or exchangeable molecules are selectively saturated and after transfer of this saturation, detected indirectly through the water signal with enhanced sensitivity. The focus of this review is on bas...
The surface oxygen exchange kinetics of bismuth oxide stabilized with 25 mol% erbia (BE25) has been studied in the temperature and pO2 ranges 773–1,023 K and 0.1– 0.95 atm, respectively, using pulse-response O–O isotope exchange measurements. The results indicate that BE25 exhibits a comparatively high exchange rate, which is rate determined by the dissociative adsorption of oxygen. Defect chem...
These three component inorganic ion-exchanger was synthesized under different condition. The most thermal and chemical properties of this material is prepared by intermixing solutions of sodium molybdate (0.1 M), sodium arsenate (0.1 M) and antimony(III) chloride (0.1 M) solution in different volume ratios at pH-1. The Ion-exchange capacity of all the samples was determined by column process. T...
The thermal denaturation of ribonuclease A has been studied by use of Fourier transform nuclear magnetic resonance by monitoring the imidazole C-2 proton resonances of the histidine residues as a function of temperature at pH 1.3. As the temperature is raised, a slow chemical exchange process results in the disappearance of the peaks corresponding to the native conformation and the appearance o...
Multinuclear solid-state nuclear magnetic resonance studies (185/187Re, 55Mn, 75As, and 1H NMR) were undertaken on a series of polycrystalline inorganic salts incorporating diamagnetic XO4 groups, X being a half-integer quadrupolar nucleus. Exploiting data acquisition protocols that were recently developed for observing undistorted half-integer quadrupole central transitions, some of the larges...
The aim of this study was to synthesize Ag-nanoclay composite by solid ion exchange, then characterize, and evaluate the antibacterial activity. This newly introduced ion exchange is a simple and low cost technique, which provides a quicker method. Without chemical treatment, nanoclay was subjected to an ion exchange process in media containing molten salt of silver at 300 and 400 °C and at dif...
We propose a new chemical detection technique in which an analyte's vibrational frequencies are interrogated directly using an array of nanomechanical resonators. This "nanomechanical resonance spectroscopy" (NRS) could permit label-free chemical detection, combining the high sensitivity of nanomechanical approaches with the high selectivity of traditional spectroscopy. A computational proof of...
Carr-Purcell-Meiboom-Gill (CPMG) relaxation measurements employing trains of 180 degrees pulses with variable pulse spacing provide valuable information about systems undergoing millisecond-time-scale chemical exchange. Fits of the CPMG relaxation dispersion profiles yield rates of interconversion, relative populations, and absolute values of chemical shift differences between the exchanging st...
BACKGROUND Nuclear Magnetic Resonance (NMR) spectroscopy offers a variety of experiments to study protein-ligand interactions at atomic resolution. Among these experiments, 15N Heteronuclear Single Quantum Correlation (HSQC)experiment is simple, less time consuming and highly informative in mapping the binding site of the ligand. The interpretation of 15N HSQC becomes ambiguous when the chemica...
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