Fabrication and characterization of Ag- and Cu-doped TiO2 nanotubes (NTs) by in situ anodization method as an efficient photocatalyst

Journal of Solid State Electrochemistry - In this study, copper (Cu) and silver (Ag)–doped TiO2 nanotubes were fabricated by in situ anodization method to improve their photocatalytic...     

Preservation of Immunoreactivity in the Photolabeling of the B72.3 Human Antibody

Abstract— A mild and efficient method of linking a dihydroflavin to the C-17 carboxylic acid side chain of protochlorophyllide, without degradation of the sensitive E ring or loss of magnesium, is described. The appended dihydroflavin was shown to quench the fluorescence of protochlorophyllide. In contrast, a dihydronicotinamide moiety was unable to effect fluorescence quenching. The relevance of these findings to a possible mechanism of action of the enzyme protochlorophyllide reductase is discussed.     

Crystal structure of phenyl bis(O-isopropylxanthato s,s′)arsenic(III)

The crystal structure of the title compound PhAs(S₂COPrⁱ)₂ has been determined by single crystal X-ray diffraction and refined by full matrix least squares analysis with anisotropic temperature factors. The crystal is monoclinic, space groupP2₁/c,a=8.889(6),b=16.174(19),c=13.506(14) Å,=102.02(7)°,V=1899.2 ų,Z=4,D _c=1.478 g cm^–3, monochromated Mo-K radiation, =0.71069 Å,=22.07 cm^–1.The geometry around the arsenic atom is square pyramidal. Each ligand is bonded to an arsenic atom through two unequal As-S bonds measuring 2.298 and 3.041 Å. The apical position is occupied by a phenyl group and a lone pair of electrons is presenttrans to the phenyl group.     

Effect of open metal sites on adsorption of polar and nonpolar molecules in metal-organic framework Cu-BTC

Atomistic grand canonical Monte Carlo simulations were performed in this work to investigate the role of open copper sites of Cu-BTC in affecting the separation of carbon monoxide from binary mixtures containing methane, nitrogen, or hydrogen. Mixtures containing 5%, 50%, or 95% CO were examined. The simulations show that electrostatic interactions between the CO dipole and the partial charges on the metal-organic framework (MOF) atoms dominate the adsorption mechanism. The binary simulations show that Cu-BTC is quite selective for CO over hydrogen and nitrogen for all three mixture compositions at 298 K. The removal of CO from a 5% mixture with methane is slightly enhanced by the electrostatic interactions of CO with the copper sites. However, the pore space of Cu-BTC is large enough to accommodate both molecules at their pure-component loadings, and in general, Cu-BTC exhibits no significant selectivity for CO over methane for the equimolar and 95% mixtures. On the basis of the pure-component and low-concentration behavior of CO, the results indicate that MOFs with open metal sites have the potential for enhancing adsorption separations of molecules of differing polarities, but the pore size relative to the sorbate size will also play a significant role.     

Topological approach to solve frame structures using topological collections and transformations

The present work tackled the modeling of frame structures using a topological approach based on the concepts of topological collections and transformations. The topological collections are used to specify the interconnection law between the frame structures and the transformations that are used to describe their behavior. As a language allowing the application of this approach, we applied the MGS (Modeling of General System) language. To validate this approach, we studied the case of two- and three-dimensional frame structures. Then, the results obtained using the MGS language are presented and compared to those obtained by the structural calculation software by the finite-element method RDM6. For both studied cases, we find that the results obtained by MGS language based on the notions of topological collections and transformations and those obtained by the RDM6 software based on the finite element method are very close, which validates our approach. Using this topological approach, any structure can be characterized by local relations between its elements, thus making it possible to dissociate its topology and its physics. Indeed, in our topological approach, we separately define the topology of the studied frame structure and the local behavior law as well as the equilibrium equations of its various components. Therefore, this topological approach might be generalized to model complex systems which can be considered as a set of local elements linked by a neighborhood relationship.     

Solution NMR spectroscopy of the human vasopressin V2 receptor, a G protein-coupled receptor

The seven-transmembrane-spanning G protein-coupled receptor (GPCR) superfamily plays many important roles in basic biology, human health, and human disease. Here, well-resolved solution NMR spectra are presented for a human GPCR, the vasopressin V2 receptor in detergent micelles. The quality of the NMR spectra indicates that backbone resonance assignments for a majority of resonances are feasible. The key to obtaining high quality spectra appears to be the coupling of methods for expressing the receptor into membranes rather than into inclusion bodies, with use of a biochemically mild lysolipid detergent for membrane extraction, protein purification, and NMR sample preparation.     

A Model for Tracking Fronts of Stress-Induced Permeability Enhancement

Using an analogy to the classical Stefan problem, we construct evolution equations for the fluid pore pressure on both sides of a propagating stress-induced damage front. Closed form expressions are derived for the position of the damage front as a function of time for the cases of thermally-induced damage as well as damage induced by over-pressure. We derive expressions for the flow rate during constant pressure fluid injection from the surface corresponding to a spherically shaped subsurface damage front. Finally, our model results suggest an interpretation of field data obtained during constant pressure fluid injection over the course of 16 days at an injection site near Desert Peak, NV.     

Electron spin resonance study of the spin dynamics in the impurity doped one-dimensional magnetic crystal (CH3)4NMnCl3:Cu2+

We have studied the spin dynamics in the one dimensional magnetic crystal, tetramethyl manganese trichloride (TMMC) doped with different concentrations of the Cu²⁺ ion, using electron spin resonance. We have observed the line widths to increase with Cu²⁺ impurity and the line shapes to deviate from the one-dimensional character.