Partial oxidation of benzene catalyzed by vanadium chloride in novel reaction-extraction-regeneration system

This paper investigates the liquid-phase partial oxidation of benzene to phenol in a novel system consisting of reactor, extractor and regenerator. Since vanadium catalyst (V³⁺) is oxidized in the reactor and therefore deactivated, the regenerator with Pd or Pt catalyst and H₂ feed is employed to regenerate the deactivated vanadium. The V⁴⁺ ion can be reduced to V³⁺ and consequently the phenol production can be enhanced. Although the regenerator can regenerate vanadium catalyst and the reaction can proceed for over 100 h, some V⁴⁺ is still present. The feed position of benzene and catalyst solution have the influence on mixing condition in the reactor and interface area between benzene and catalyst solution. Counter current flow operation with the feeds of catalyst solution and benzene at the top and the bottom respectively shows the highest phenol production. The operating temperature of reactor, extractor and regenerator showed insignificant effect on phenol production rate.     

Transport of carnitine and acetylcarnitine by carnitine/organic cation transporter (OCTN) 2 and OCTN3 into epididymal spermatozoa

Carnitine and acetylcarnitine are important for the acquisition of motility and maturation of spermatozoa in the epididymis. In this study, we examined the involvement of carnitine/organic cation transporter (OCTN) in carnitine and acetylcarnitine transport in epididymal spermatozoa of mice. Uptake of both compounds by epididymal spermatozoa was time-dependent and partially Na(+)-dependent. Kinetic analyses revealed the presence of a high-affinity transport system in the spermatozoa, with K(m) values of 23.6 and 6.57 muM for carnitine and acetylcarnitine respectively in the presence of Na(+). Expression of OCTN2 and OCTN3 in epididymal spermatozoa was confirmed by immunofluorescence analysis. The involvement of these two transporters in carnitine and acetylcarnitine transport was supported by a selective inhibition study. We conclude that both Na(+)-dependent and -independent carnitine transporters, OCTN2 and OCTN3, mediate the supply of carnitine and acetylcarnitine to epididymal spermatozoa in mice.     

Asian Mussel Watch Program: contamination status of polybrominated diphenyl ethers and organochlorines in coastal waters of Asian countries

Mussel samples were used in this study to measure the levels of polybrominated diphenyl ethers (PBDEs) and organochlorines (OCs) in the coastal waters of Asian countries like Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, the Philippines, and Vietnam. PBDEs were detected in all the samples analyzed, and the concentrations ranged from 0.66 to 440 ng/g lipid wt. Apparently higher concentrations of PBDEs were found in mussels from the coastal waters of Korea, Hong Kong, China, and the Philippines, which suggests that significant sources of these chemicals exist in and around this region. With regard to the composition of PBDE congeners, BDE-47, BDE-99, and BDE-100 were the dominant congeners in most of the samples. Among the OCs analyzed, concentrations of DDTs were the highest followed by PCBs > CHLs > HCHs > HCB. Total concentrations of DDTs, PCBs, CHLs, and HCHs in mussel samples ranged from 21 to 58 000, 3.8 to 2000, 0.93 to 900, and 0.90 to 230 ng/g lipid wt., respectively. High levels of DDTs were found in mussels from Hong Kong, Vietnam, and China; PCBs were found in Japan, Hong Kong, and industrialized/urbanized locations in Korea, Indonesia, the Philippines, and India; CHLs were found in Japan and Hong Kong; HCHs were found in India and China. These countries seem to play a role as probable emission sources of corresponding contaminants in Asia and, in turn, may influence their global distribution.     

Improvement of transformation efficiency by bioactive-beads-mediated gene transfer using DNA-lipofectin complex as entrapped genetic material

The efficiency of bioactive-beads-mediated plant transformation was improved using DNA-lipofectin complex as the entrapped genetic material instead of naked DNA used in the conventional method. In the improved method, beads aggregated and formed clusters around the protoplasts resulting in a 4-fold higher transformation efficiency than that by the conventional method.     

Film boiling heat transfer around a vertical finite‐length cylinder with a convex hemispherical bottom

The film boiling heat transfer around a vertical silver cylinder with a convex hemispherical bottom was investigated experimentally in quiescent water at atmospheric pressure. The experiments have been carried out using a quenching method. The diameter and length of the test cylinder are 32 mm and 48 mm, respectively. The test cylinder was heated to about 600 °C in an electric furnace and then cooled in saturated or subcooled water with an immersion depth of about 100 mm. The degree of liquid subcooling was varied from 0 K to 30 K. The analytical solutions for saturated and subcooled boiling are obtained by applying a two‐phase boundary layer theory for vapor film with a smooth interface. The experimental data correlates within ±15% based on the proposed prediction method. Also, the lower limit of film boiling was examined in terms of wall heat flux and degree of superheating. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20289     

Diverse Morphologies of Self‐Assemblies from Homoditopic 1,18‐Nucleotide‐Appended Bolaamphiphiles: Effects of Nucleobases and Complementary Oligonucleotides

The synthesis of 1,18‐nucleotide‐appended bolaamphiphiles (1 , 2 , 4 , and 6) is reported, in which a 3′‐phosphorylated guanidine, adenosine, thymidine, or cytidine is connected to each end of an octadecamethylene chain. Single‐component self‐assemblies and binary self‐assemblies with the complementary oligonucleotides dC ₂₀ , dT ₂₀ , dA ₂₀ , and dG ₂₀ are studied by atomic force microscopy, powder X‐ray diffraction analysis, temperature‐dependent UV absorption, circular dichroism, and attenuated total‐reflection Fourier‐transform infrared spectroscopy. The single‐component self‐assembly of 1 forms a two‐dimensional sheet, whereas the binary self‐assembly 1 / dC ₂₀ gives helical nanofibers. Non‐helical nanofibers are observed for the single‐component self‐assemblies of 2 and 4 , and helical nanofibers form from the binary self‐assembly 2 / dT ₂₀ . Interestingly, helical nanorod structures are obtained from the binary self‐assembly 4 / dA ₂₀ , and the aligned nanorods form a nematic phase. The single‐component and binary self‐assemblies from 6 give unilamellar vesicles owing to a lack of stacking interaction between the cytosine moieties.     

A detailed study of H2 plasma passivation effects on GaAs/Si solar cell

The hydrogen plasma passivation effects of MOCVD-grown GaAs solar cell on Si substrate have been studied in detail. To get a more reproducible increase of conversion efficiency and test the thermal stability of the plasma-exposed GaAs/Si solar cell, both the plasma exposure and post-passivation annealing conditions were optimized. Annealing the H₂ plasma passivated GaAs/Si solar cell at 450°C in AsH₃/H₂ ambient seems a very essential parameter to restore the carrier concentration, especially, without losing the beneficial effects of H incorporation into GaAs on Si. For the H₂ plasma passivated GaAs/Si solar cell, a highest conversion efficiency of 18.3% was obtained compared with that of the as-grown cell (16.6%) due to the H passivation effects on nonradiative recombination centers, which increased the minority carrier lifetime.     

Transformation-Induced Microcracks and Their Arrest with Different Deformation Temperatures in a Medium Mn Steel

Metallurgical and Materials Transactions A - In the present study, the temperature dependence of microstructure and damage evolution in the medium Mn steel was investigated by tensile testing and...