Raman scattering tensors of adenine

Polarized Raman scattering measurements have been made of a single crystal of adenine dihydrochloride (adenine-2H+) by the use of Raman microscope with 488.0 nm excitation. The adenine-2H+ crystal belongs to the space group Pnma (orthorhombic), and Raman intensities of Iaa, Ibb, Icc and Iac (which correspond to the aa, bb, cc and ac components of the crystal Raman tensor) have been determined for each Raman band. The depolarization ratios of Raman bands have been observed for fully random molecular orientations in an adenine 6N HCl aqueous solution. From these experimental data, and by taking the known crystal structure into account, anisotropic and isotropic molecular Raman scattering tensors have been determined for each vibrational mode of the adenine residue.     

Photocatalyzed mineralization of a trimethylated phenol in oxygenated aqueous titania. An alternative to microbial degradation

The most methylated phenolic substrate in coal tar creosote, 2,3,5-trimethylphenol (TMP), was mineralized photocatalytically to CO₂ and water at pH 3 in illuminated air-equilibrated titania dispersions. Trimethylhydroquinone and trimethylbenzoquinone were the two major aromatic intermediates; trace amounts of trimethylcatechol also formed. Complete mineralization was achieved in oxygenated solutions in ～1 h; conversion of TMP was over in less than ～25 min in aerated solutions and in less than 12 min in oxygenated solutions.     

Lattice Constants and Compositions of Manganese-Bearing Ferrites

When manganese-bearing ferrites (Mn _x Fe_{3- x} O_4-delta, with x = 0.17-1.09) were prepared in the present study via a solid-state reaction, manganese ions were incorporated into the lattice sites of the ferrites in the divalent state. The lattice constant ( a ₀) of those ferrites increased linearly as the manganese composition x increased. A ferrite with x = 1.28 contained manganese ions with a valence state higher than 3+; however, no further increase in a ₀ occurred at valences higher than 2+.     

New amphoteric surfactants containing a 2-hydroxyalkyl group: II. the dependence of physicochemical properties on the pH value for N-(2-hydroxyethyl)-N-(2-hydroxyalkyl)-β-alanines

The dependence of physicochemical properties on the pH of micellar solutions for N-(2-hydroxyethyl)-N-(2-hydroxyalkyl)-β alanines (HAA) was studied by means of a differential titration method (DTM), Fourier transform infrared (FTIR) spectra, and measurements of critical micelle concentration, surface tension, and foaming power. The aspect of the dissociation of HAA was pursued by DTM. The mutual transformation among cationic, zwitterionic, and anionic forms with the change of pH range was confirmed by FTIR spectroscopy. The micelle formation energy was determined at each pH value. Further, the dependence of surface active properties on the pH value for the adducts of ethylene oxide to Na-HAA was also investigated.     

Formation of refractory ring-expanded triazine intermediates during the photocatalyzed mineralization of the endocrine disruptor amitrole and related triazole derivatives at UV-irradiated TiO2/H2O interfaces

Amitrole (ATz, 3-amino-1H-1,2,4-triazole) is a widely employed herbicide with strong estrogenic activity that can lead to abnormalities of the thyroid gland and can cause mutations. The photocatalytic transformation of ATz was carried out at the UV-irradiated TiO2/H2O interface, along with the triazole derivatives Tz (1H-1,2,4-triazole) and DaTz (3,5-diamino-1H-1,2,4-triazole) to assess the decomposition of these herbicides, to identify intermediates, and to elucidate some mechanistic details of the ATz degradation. Conversion of the nitrogens of these triazoles to NH4+ and/ or NO3- ions occurs competitively and depends on the number of amine functions on the five-membered triazole rings. Photomineralization of the substrates in terms of loss of nitrogen to NH4+/NO3- was rather low (ca. 25-40%) for each of the triazoles, whereas evolution of CO2 (loss of TOC) was more significant (60-70%), indicating considerable retention of nitrogen in the intermediate products. UV-Vis spectroscopy, TOC assays, FT-IR spectroscopy, proton NMR spectrometry, electrospray LC-MS, and molecular orbital calculations were brought to bear in assessing the temporal course of the photocatalyzed process(es). Results show that after cleavage of the triazole ring, the various intermediate fragments recombine to yield ring-expanded six-membered triazine intermediates, which slowly degrade to give the refractory cyanuric acid under the conditions used.     

Effect of expander shape on cooling characteristics by using a model pulse tube refrigerator

Pulse tube refrigerators do not have moving parts in the cold section, and they have low vibration, high reliability, and long life. The expander in refrigerators typically has an inverted U or coaxial shape because this attains a wider absorber area, lower height, and compactness. However, the performance of a Stirling-type pulse tube refrigerator is inferior to that of a Stirling refrigerator. Cooling characteristics of the pulse tube refrigerator greatly depend on the shape of the expander. In this study, an inertance-type refrigerator, which uses ambient air for the working gas, was developed to examine the effect of expander shape. This refrigerator model with changeable expander operated with a Stirling cycle, and it was composed of a reciprocating compressor, after-cooler, regenerator, absorber, pulse tube, hot-end, and inertance tube with reservoir. The following expander shapes were tested: in-line, L shape, L-L shape, and coaxial shape. The effect of expander shape on cooling capacity was examined experimentally and numerically using the model pulse tube refrigerator. The results of experiments showed that the L shape expander had the highest performance and the coaxial expander had the lowest performance. In addition, the characteristics of the gas flow in each expander were confirmed by fluid dynamics analysis.     

Measurements of the surface tension for R290, R600a and R290/R600a mixture

The surface tensions of R290, R600a and R290/R600a mixture have been measured by the modified differential capillary-rise method. Twenty-two data points for R290 and 21 data points for R600a were obtained in the temperature range between 273 K and 354 K, and 43 data points for R290/R600a mixture on three isotherms of 278 K, 300 K and 320 K were obtained. The experimental uncertainties of temperature and surface tension are estimated to be within 20 mK and 0.2 mN m⁻¹, respectively. Surface tension correlations as a function of temperature for pure R290 and R600a were formulated in the temperature range between 253 K and critical temperature, and the correlation as a function of the composition for R290/R600a mixture was discussed at 278 K, 300 K and 320 K. It is found that the surface tension for R290/R600a mixture can be reproduced by the simple mixing rule by mole fraction with the correlations of both pure components.     

CP-PACS: A massively parallel processor at the University of Tsukuba

Computational Physics by Parallel Array Computer System (CP-PACS) is a massively parallel processor developed and in full operation at the Center for Computational Physics at the University of Tsukuba. It is an MIMD machine with a distributed memory, equipped with 2048 processing units and 128 GB of main memory. The theoretical peak performance of CP-PACS is 614.4 Gflops. CP-PACS achieved 368.2 Gflops with the Linpack benchmark in 1996, which at that time was the fastest Gflops rating in the world.CP-PACS has two remarkable features. Pseudo Vector Processing feature (PVP-SW) on each node processor, which can perform high speed vector processing on a single chip superscalar microprocessor; and a 3-dimensional Hyper-Crossbar (3-D HXB) Interconnection network, which provides high speed and flexible communication among node processors.In this article, we present the overview of CP-PACS, the architectural topics, some details of hardware and support software, and several performance results.