Conformations of trimethoxymethylsilane: matrix isolation infrared and ab initio studies

Conformations of trimethoxymethylsilane were studied using matrix isolation infrared spectroscopy and ab initio computations. Trimethoxymethylsilane was trapped in both argon and nitrogen matrixes using heated nozzle effusive sources and a supersonic jet source, in an effort to alter the conformational population in the matrix. Ab initio calculations were carried out at the HF and B3LYP level using 6-31++G basis set to support our experimental observations. The frequencies computed at the B3LYP level was found to fit well with our experimental data. A conformer with a C1(g(+/-)g(+/-)t) structure was predicted by our computations to be the ground state conformer.     

Genetic risks to man from exposure to long-lived radionuclides

Ionizing radiation, irrespective of whether it is received from external sources or from internally-deposited radionuclides, is capable of causing genetic damage that will be transmitted from one generation to the next. Since strictly relevant human data is limited at present, there is no alternative to the use of data collected in experimental mammals for estimating genetic risks associated with the exposure of human populations to ionizing radiation.Animal studies reveal that plutonium reaching the testes and concentrates in the interstitial tissue but is later aggregated by macrophages, apparently leading to a reduction in effectiveness. For protracted alpha irradiation from testicular plutonium in the mouse, the RBE (relative biological effectiveness) for genetic effects of concern may be in a range of between 10 and 20, relative to chronic gamma irradiation. In female mice, plutonium appears to be much less effective although the data is very limited.Studies with beta emitters provide reasonable grounds for believing that in the case of chronic exposures to tritium, the RBE value may be about 2, whereas for others such as carbon-14, it may not be significantly different from unity.These and other results support the view that for plutonium alpha rays, the genetic risks following exposure of human males may be 10–20 times that estimated for chronic, low level, low LET irradiation, per unit absorbed testicular dose; for tritium exposures, the risks may be higher by a factor of 2, (again, relative to chronic gamma ray exposures) while for carbon-14, the risks are the same as that for chronic gamma irradiation. For estimating genetic risks following exposure of human females to radionuclides, in the absence of adequate data, it would be prudent to assume that the risks will be similar to those for irradiation of males.     

Prediction of nanofluid viscosity using multilayer perceptron and Gaussian process regression

Journal of Thermal Analysis and Calorimetry - More than a decade, a numerous experimental and theoretical studies of thermophysical properties of nanofluids are conducted to reveal its heat...     

Probing the Binding of Syzygium-Derived α-Glucosidase Inhibitors with N- and C-Terminal Human Maltase Glucoamylase by Docking and Molecular Dynamics Simulation

Human maltase glucoamylase (MGAM) is a potent molecular target for controlling post prandial glucose surplus in type 2 diabetes. Binding of small molecules from Syzygium sp. with α-glucosidase inhibitory potential in MGAM has been investigated in silico. Our results suggest that myricetin was the most potent inhibitor with high binding affinity for both N- and C-terminals of MGAM. Molecular dynamics revealed that myricetin interacts in its stretched conformation through water-mediated interactions with C-terminal of MGAM and by normal hydrogen bonding with the N-terminal. W1369 of the extended 21 amino acid residue helical loop of C-terminal plays a major role in myricetin binding. Owing to its additional sugar sites, overall binding of small molecules favours C-terminal MGAM.     

Synthesis of Nordstrandite and Nordstrandite-Derived Layered Double Hydroxides of Li and Al: A Comparative Study with the Bayerite Counterpart

The layered double hydroxides (LDHs) of Li and Al can be synthesized from the four polymorphs of Al(OH)₃, namely gibbsite, bayerite, nordstrandite, and doyleite. The crystal structure of this class of compounds depends on the type of the precursor used due to their topotactic reaction mechanism. While the LDHs derived from gibbsite and bayerite yield different crystal structures, the incorporation of Li into nordstrandite was expected to yield new LDH structures different from those derived from gibbsite and bayerite. The structure of nordstrandite derived LDHs were however identical to that derived from the bayerite counterpart. The absence of symmetry in the interlayer of nordstrandite (C₁) makes it unsuitable to accommodate the intercalating anions with different molecular symmetries. To make the interlayer gallery suitable for the anions, the metal hydroxide layers of the nordstrandite translate, transforming nordstrandite to bayerite. The bayerite with site symmetries O_h and C₂ stabilizes the anions in the interlayer by hydrogen bonding. The transformation of nordstrandite to bayerite, when soaked in lithium salt solution is, therefore, a manifestation of the intercalating anions.     

Thermal cycling,DLTS, and PEC studies on LEC gallium arsenide

This paper discusses the growth of gallium arsenide single crystals using the LEC technique. The Semi-insulating gallium arsenide was studied. The defect investigations were made by DLTS and etching studies. The variation of deep level concentration along the wafer was estimated using DLTS. The fabrication and efficiency of the PEC Solar cells are also reported.     

Enhancement of thermopower in the highT c superconductor YBa2Cu3O7 and related compounds

The absolute thermopower of single phase YBa₂Cu₃O₇ and Y_0.8Er_0.2Ba₂Cu₃O₇ has been measured in the range 250 K to the superconducting transition temperature. It is found that these compounds show a large enhancement of thermopower in the range 150 K down toT _c. This enhancement shows a steep exponential drop as the temperature increases from the transition temperature. The temperature variation of the enhancement is too steep to be accounted for by electron-phonon or electron-local structural excitation mechanisms.