A numerical study of the target system of an ADSS with different flow guides

The mechanical design of the target module of an accelerator driven subcritical nuclear reactor system (ADSS) calls for an analysis of the related thermal-hydraulic issues because of large amount of heat deposition in the spallation region during the course of nuclear interactions with the molten lead bismuth eutectic (LBE) target. The LBE also should carry the entire heat generated as a consequence of the spallation reaction. The problem of heat removal by the LBE is a challenging thermal-hydraulic issue. For this, one has to examine the flows of low Prandtl number fluids (LBE) in a complex ADSS geometry. In this study, the equations governing the laminar flow and thermal energy are solved numerically using the streamline upwind Petrov-Galerkin (SUPG) finite element (FE) method. The target systems with a straight and a nozzle guide have been considered. The principal purpose of the analysis is to trace the flow and temperature distribution and thereby to check the suitability of the flow guide in avoiding the recirculation or stagnation zones in the flow space that may lead to hot spots.      

Fragmentation of chitosan by ultrasonic irradiation

Kinetics of chitosan fragmentation by ultrasonic irradiation at frequency of 20 kHz, and the effects of experimental variables (power of ultrasound, chitosan concentration and solution temperature) on fragmentation were investigated. The kinetics studies were followed by measuring solution viscosity of the original and its fragments, and determining average number of chain scission of the fragments. The effects of ultrasonic power, chitosan concentration and solution temperature on fragmentation process were followed by viscometry and size exclusion chromatography. The chemical structure of the original chitosan and its fragments were examined by (1)H NMR spectroscopy and elemental analysis. The experimental results showed that the rate of fragmentation increased with an increase in power of ultrasound. Chain scission increased with an increase in power of ultrasound; and solution temperature, but a decrease in chitosan concentration. The chemical structure and polydispersity of the original and the fragments were nearly identical. A model based on experimental data to describe the relationship between chain scission and experimental variables (power of ultrasound; irradiation time; reduced concentration, c[eta]; and solution temperature) was proposed. It was concluded that ultrasonic irradiation is a suitable method to perform partial depolymerization and to obtain moderate macromolecules from large ones.     

CdS quantum dot-sensitized ZnO nanorod-based photoelectrochemical solar cells

ZnO nanorods have been grown using ZnO seed layer onto ITO-coated glass substrates. CdS quantum dots have been deposited onto ZnO nanorods using simple precursors by chemical method and the assembly of CdS quantum dots with ZnO nanorod has been used as photo-electrode in quantum dot-sensitized solar cells. X-ray diffraction results show that ZnO seed layer, ZnO nanorods, and CdS quantum dot-sensitized ZnO nanorods exhibit hexagonal structure. The particle size of CdS nanoparticle is 5 nm. The surface morphology studied using scanning electron microscope shows that the top surface of the vertically aligned ZnO nanorods is fully covered by CdS quantum dots. The ZnO nanorods have diameter ranging from 100 to 200 nm. The absorption spectra reveal that the absorption edge of CdS quantum dot-sensitized ZnO nanorods shift toward longer wavelength side when compared to the absorption edge of ZnO. The efficiency of the fabricated CdS quantum dot-sensitized ZnO nanorod-based solar cell is 0.69% and is the best efficiency reported so far for this type of solar cells.     

Extreme statistics of complex random and quantum chaotic states

Complex random states have the statistical properties of the Gaussian and circular unitary ensemble eigenstates of random matrix theory. Even though their components are correlated by the normalization constraint, it is nevertheless possible to derive compact analytic formulas for their extreme values' statistical properties for all dimensionalities. The maximum intensity result slowly approaches the Gumbel distribution even though the variables are bounded, whereas the minimum intensity result rapidly approaches the Weibull distribution. Since random matrix theory is conjectured to be applicable to chaotic quantum systems, we calculate the extreme eigenfunction statistics for the standard map with parameters at which its classical map is fully chaotic. The statistical behaviors are consistent with the finite-N formulas.     

Effect of Isomerism in the Dipolar Interaction of Benzene with Butanol

Sound velocity, density, and viscosity values were measured at 303 K in four binary systems of benzene + 1-, 2-, tert-, or iso-butanol. From these data, acoustical parameters, such as adiabatic compressibility, free length, free volume, and internal pressure were estimated using the standard relations. The results are interpreted in terms of molecular interaction between the components of the mixtures. Observed excess value in all the mixture indicates that the molecular symmetry existing in the system is highly disturbed by the nonpolar benzene molecules. Interaction energy terms of the statistical mixing are also verified for these binary systems and the dipole-dipole interactions are found to be predominantly present and are sharply affected by the isomeric forms of butanol.     

Synthesis,characterization, and anti-cancer activity of chalcone derivatives as-potent anaplastic lymphoma kinase inhibitors

Structural Chemistry - Chalcone derivatives (7a–k) have been synthesized and characterized by 1H-NMR, 13C-NMR, mass, and elemental analysis. The synthesized compounds 7a, 7d, and 7g have been...     

Crystallization,spectral, and thermal characterization of <Emphasis Type="SmallCaps">l</Emphasis>-histidine methyl ester dihydrochloride (LHMED)

A novel nonlinear optical semi-organic single crystal of l-histidine methyl ester dihydrochloride was grown by slow evaporation solution growth method at an ambient temperature. The grown crystal was characterized by single crystal X-ray diffraction. Functional groups and the modes of vibrations were identified by FT–IR spectroscopy. The chemical composition of the crystal was confirmed by Energy dispersive X-ray analysis. The optical behavior of the crystal was examined by UV spectral analysis, which shows the absence of absorption between the wavelengths ranging from 230 to 1000 nm. The optical band gap of the grown crystal was estimated and is found to be 5.35 eV. The thermal behavior of the crystal was investigated by thermogravimetric and differential thermal analyses. The nonlinear optical property of the grown crystal was confirmed by the powder technique of Kurtz and Perry.     

Synthesis,Spectroscopic Analysis,and In-Vitro Antimicrobial Evaluation of some Tetrahydrobenzo[a]Xanthene-11-Thiones

Abstract

A series of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones were synthesized by the reaction of substituted 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones with Lawesson's Reagent in toluene under standard reaction conditions. All synthesized compounds were characterized by IR, NMR (¹H and ¹³C), and mass spectra. Moreover, 2D-NMR (HOMOCOSY, HSQC, and HMBC) studies were also performed for compound 10b. The synthesized compounds were also screened for their antibacterial activities.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]     

Effect of pressure on pedal motion in stilbene molecular crystals and its dependence on the crystallographic site

We report computer simulation of a stilbene molecular crystal as a function of pressure up to 4 GPa. Molecular structure and the crystal structure of stilbene have been characterized by calculating the radial distribution function and dihedral angle distribution, features associated with pedal motion and cell parameters. Results suggest that the population of minor conformer at site 2 disappears altogether above 1.25 GPa. In contrast, the population of minor conformer at site 1 remains at around 12%. Pedal motion is not observed beyond a pressure of 0.8 and 1.4 GPa at site 1 and site 2, respectively. Specific heat and compressibility exhibit an anomaly around 1.25 GPa. The anomaly seems to be associated with the disappearance of pedal motion at site 2. Initially, increase in pressure leads to an increase in the magnitude of lattice energy, but beyond 0.5 GPa it decreases.