Quantum Effects on Hydrogen Isotopes Adsorption in Nanopores

We have investigated the applicability of simulations and theoretical techniques for exploring the selectivities of hydrogen isotopes. We have simulated the adsorption isotherms of H₂ in an idealized carbon slit pore at 77 K by using the grand canonical Monte Carlo simulations with the Feynman-Hibbs effective potential (FH-GCMC) and the rigorous path integral method (PI-GCMC), and we obtained good agreement between the isotherms from both simulations. This suggests that FH-GCMC, which uses the approximative Feynman-Hibbs treatment, is as useful as PI-GCMC for exploring H₂ adsorption at 77 K. Moreover, we show that the ideal adsorption solution theory (IAST) can predict the selectivity of D₂ over H₂ in the interstices of single-wall carbon nanotube (SWNT) bundles at 77 K (below 0.1 MPa) very well by comparing the obtained results with the mixture adsorption FH-GCMC simulations. This indicates that IAST is also applicable to the estimation of the selectivity of D₂ over H₂ at moderate pressures and at 77 K from experimental single-component adsorption isotherms. We also demonstrate that the FH-GCMC simulation can reproduce the experimental adsorption isotherms of H₂ and D₂ in aluminophosphate AlPO₄-5 at 77 K. Finally, we analyze the selectivity of D₂ over H₂ by IAST with the experimental single-component adsorption isotherms of H₂ and D₂ at 77 K for a variety of adsorbents: AlPO₄-5, activated carbon fibers (ACFs), HiPco SWNT, and SWNHs. The selectivities predicted by the experimental adsorption data based on the results from the FH-GCMC simulations are presented and discussed.     

Comparison of CTOD standards: BS 7448-Part 1 and revised ASTM E1290

Crack tip opening displacement (CTOD) has been calculated using the plastic hinge model with an assumed rotational center since the British Standards Institution (BS) standardized BS5762 in 1979. The American Society for Testing and Materials (ASTM) accepted the plastic hinge model and standardized E1290 in 1989. However, ASTM revised E1290 in 2002, and has proposed a conversion from J to CTOD. CTOD-based fracture toughness evaluation has been widely used for the defect assessment of many welded structural components, and two different CTOD calculations could lead to confusion for Fitness-for-Service. In this study, the effects of CTOD testing methodologies on CTOD values were investigated according to round robin tests conducted by the Japan Welding Engineering Society (WES), and the concept of CTOD as a fracture parameter is discussed.     

Synthesis of Pd-Sn nanoparticles by ultrasonic irradiation and their electrocatalytic activity for oxygen reduction

Nanoparticles of Pd-Sn were prepared under various conditions by applying ultrasonic irradiation, and their electrocatalytic activity for oxygen reduction was evaluated in 0.5 M KOH. The average size of Pd-Sn nanoparticles thus prepared was about 3-5 nm. The Pd in Pd-Sn nanoparticles was found to be mostly in the metallic state. The electrocatalytic activity of the Pd-Sn nanoparticles for the oxygen reduction reaction (ORR) is greater than Pt or Pd nanoparticles in alkaline media. The molar ratio of Pd to Sn metal ions in the synthesizing solution, their initial concentrations, the concentration of ethanol, which increases primary hydrogen radicals during sonolysis, and the concentration of citric acid were found to affect the size distribution of the Pd-Sn nanoparticles, and therefore, those factors controlled the electrocatalytic activity for ORR. Particularly, the concentration of citric acid was found to be important for controlling the surface property on Pd-Sn particles to adjust the electrocatalytic activity for ORR.     

Effects of additives on prebreakdown phenomena in n-hexane

Prebreakdown phenomena in n-hexane are observed in detail for positive and negative polarities by using simultaneously a high speed schlieren technique and an LED current measuring system, when an impulse voltage (1.1/225 μs) is applied to a point-to-plane electrode gap. Furthermore, the effects of several additives on the streamer propagation are investigated. Especially the effects of electron-trapping additives on negative streamer propagation and of low ionization potential additives on the positive streamer propagation, are examined, as is a correlation between the shape and the propagation velocity of the streamers     

Tachykinins and tachykinin receptors in bone

Adrenomedullin (AM) was originally characterized in extracts of an adrenal medullary tumor. Since this original finding the peptide and its mRNA have also been found in the adrenal cortex, specifically, in the cells of the aldosterone-secreting zona glomerulosa. It is clear that the synthesis of AM is actively regulated in both cortex and medulla. Much research effort has been focused on identifying a role for AM in the adrenal gland. To date, no consistent effect on medullary catecholamine biosynthesis has been demonstrated. In the cortex the actions of AM are controversial and appear to depend on both the tissue preparation used and on the specific receptor population expressed in the individual gland. The results of further studies on the long-term actions of AM on adrenal growth and differentiation are awaited with interest.     

Uniform carbon‐nanotube emitter for field‐emission displays

Abstract— The synthesis of carbon‐nanotube (CNT) field emitters for FEDs by thermal chemical vapor deposition (CVD) and their structural and emission characterization are described. Multi‐walled nanotubes (MWNTs) were grown on patterned metal‐base electrodes by thermal CVD, and the grown CNTs formed a network structured layer covering the surfaces of the metal electrode uniformly, which realized uniform distribution of electron emission. A technique for growing narrow MWNTs was also developed in order to reduce the driving voltage. The diameter of MWNT depends on the growth temperature, and it has changed from 40 nm at the low temperature (675°C) to 10–15 nm at the high temperature (900–1000°C). Moreover, narrower MWNTs were grown by using the metal‐base electrode covered with a thin alumina layer and a metal catalyst layer. Double‐walled nanotubes (DWNTs) were also observed among narrow MWNTs. The emission from the narrow CNTs showed a low turn‐on electric field of 1.5 V/μm at the as‐grown layer.     

Preparation of detergent-lipase complexes utilizing water-soluble amphiphiles in single aqueous phase and catalysis of transesterifications in homogeneous organic solvents

A novel method of preparing detergent-enzyme complexes that can be employed in organic media was developed utilizing newly synthesized water-soluble nonionic gemini-type detergents, N,N-bis(3-D-gluconamidopropyl)-3-(dialkyl-L-glutamatecarbonyl)propanamides (BIG2CnCA: n = 10,12,14,16,18) and N,N-bis(3-D-lactonamidopropyl)-3-(dialkyl-L-glutamatecarbonyl)propanamides (BIL2CnCA: n = 16,18), and nonionic twin-headed detergents, N,N-bis(3-D-gluconamidopropyl)alkanamides (BIG1Cn: n = 12,14,16,18,delta9). This method simply entails mixing a selected enzyme with an appropriate detergent in an aqueous solution followed by lyophilization, and it offers the advantages of enhanced enzymatic activity in organic solvents and eliminates both enzyme loss and the necessity for an organic solvent in the preparation stage. Using various modified lipases originating from Aspergillus niger (Lipase A), Candida rugosa (Lipase C), Pseudomonas cepacia (Lipase P), and porcine pancreas (PPL), prepared using the novel method and detergents, including conventional synthesized nonionic detergents such as dialkyl N-D-glucona-L-glutamates (2CnGE: n = 12,18delta9) and octanoyl-N-methylglucamide (MEGA-8), enantioselective transesterifications of 6-methyl-5-hepten-2-ol (sulcatol) and 2,2-dimethyl-1,3-dioxolane-4-methanol (solketal) with a vinyl or isopropenyl carboxylate were carried out in an organic solvent. The modified lipase activity was influenced by both the lipases and the structure of the detergents. The value for the hydrophile-lipophile balance (HLB) of the detergent provided a means of correlating the structure and the obtained modified lipase activity. For detergents of the same class with a HLB value of approximately 9 and 12, the highest activity was obtained for Lipase A and Lipase P, and Lipase C and PPL, respectively. Among detergents of the same HLB value tested, the gemini-type detergents possessing the most bulky head and tail were most effective as a modifier for lipases of all types. The preparation and reaction conditions for these novel gemini-type detergent-modified lipases were optimized using BIG2C12CA (HLB = 9.4) by studying the effect of the detergent/lipase ratio and the nature of organic solvents on the complex formation. The high enzymatic activities of the BIG2C12CA-modified lipases were independent of the solubility of the lipases in organic solvents, unlike in the case of 2CnGE-modified lipases prepared using the conventional suspension system.     

Electronic Structures of Two-Phase Microstructures in Pb-doped Bi2Sr2CaCu2O y

We have performed scanning tunneling microscopy/spectroscopy (STM/STS) on single crystals of heavily Pb-doped Bi ₂ Sr ₂ CaCu ₂ O _y (Pb-Bi2212). The obtained STM images clearly demonstrated phase separation into the and phases with lamella-type and new zigzag-like microstructures. From the site-specified tunneling measurements, it was directly confirmed that the phase possesses higher T _c . This suggests that the phase boundaries act as strong pinning sites especially at higher temperatures.     

Expression of CD44 variant 6 and lymphatic invasion: importance to lymph node metastasis in gastric cancer

Lymph node metastasis is a critical prognostic factor for gastric cancer. In the present investigation we examined clinicopathologic factors influencing the metastatic processes to the lymph mode and their prognostic importance. A randomly selected group of 98 patients with adenocarcinomas of the stomach who underwent gastrectomy plus systematic lymph node dissection at Osaka Police Hospital from 1991 to 1996 were analyzed. Altogether 37 (38%) cancers were positive for CD44 variant 6 (v6) staining, 31 (32%) were intermediately stained, and 30 (30%) were negative. CD44-v6 expression correlated well with lymph node metastasis. Expression of CD44-v6 and lymphatic invasion were independent risk factors for metastatic lymph nodes. Among the patients with CD44-v6-positive and lymphatic invasion-positive cancers, 88% had lymph node metastasis, whereas only 13% of patients negative for both factors had lymph node metastasis. Although CD44-v6 expression and lymphatic invasion have been reported to be risk factors for recurrence and a poor prognosis, in this investigation these factors were found not to be significant for hematogenous and lymphatic recurrences or overall survival rates. Thus expression of CD44-v6 and lymphatic invasion may regulate lymph node metastases from gastric cancer.     

Autocrine/paracrine role of adrenomedullin in cultured endothelial and mesangial cells

Neuropsychological profiles were assessed in a large group of nondemented control subjects (n = 261) and individuals with dementia of the Alzheimer type (DAT) (n = 407) by subjecting their psychometric test results to a factor analysis. Nondemented control subjects were functionally homogeneous with only one factor accounting for the results. The results of the factor analysis on the very mild DAT and mild DAT groups, however, yielded a mental control/frontal factor, a memory-verbal/temporal factor, and a visuospatial/parietal factor. Forty-one of the original set of participants came to autopsy an average of 5.1 years after psychometric testing and had neurofibrillary tangles, total senile plaques, and cored senile plaques estimated from frontal, temporal, and parietal regions. The results of correlations indicated that the relative burden of cored senile plaques was systematically related to the three psychometric factors. These results suggest a connection between the specific functions as defined by neuropsychological measures and specific neuropathology occurring in associated areas of cortex.