The effect of Na addition on the first hydrogen absorption kinetics of cast hypoeutectic Mg–La alloys

With superior properties of Mg such as high hydrogen storage capacity (7.6 wt% H/MgH₂), low price, and low density, Mg has been widely studied as a promising candidate for solid-state hydrogen storage systems. However, a harsh activation procedure, slow hydrogenation/dehydrogenation process, and a high temperature for dehydrogenation prevent the use of Mg-based metal hydrides for practical applications. For these reasons, Mg-based alloys for hydrogen storage systems are generally alloyed with other elements to improve hydrogen sorption properties. In this article, we have added Na to cast Mg–La alloys and achieved a significant improvement in hydrogen absorption kinetics during the first activation cycle. The role of Na in Mg–La has been discussed based on the findings from microstructural observations, crystallography, and first principles calculations based on density functional theory. From our results in this study, we have found that the Na doped surface of Mg–La alloy systems have a lower adsorption energy for H₂ compared to Na-free surfaces which facilitates adsorption and dissociation of hydrogen molecules leading to improvement of absorption kinetic. The effect of Na on the microstructure of these alloys, such as eutectic refinement and a density of twins is not highly correlated with absorption kinetics.     

Characterization and electrochemical properties of CF4 plasma-treated boron-doped diamond surfaces

The effect of CF₄ plasma etching on diamond surfaces, with respect to treatment time, was investigated using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. SEM observations and Raman spectra indicated an increase in surface roughening on a scale of 10–20 nm, and an increase in crystal defect density was apparent with treatment time in the range of 10 s to 30 min. In contrast, alteration of the diamond surface terminations from oxygen to fluorine was found to be rather rapid, with saturation of the F/C atomic ratio estimated from XPS analysis after treatment durations of 1 min and more. The redox kinetics of Fe(CN)₆^3−/4− was also found to be significantly modified after 10 s of CF₄ plasma treatment. This behavior shows that C–F terminations predominantly affect the redox kinetics compared to the effect on the surface roughness and crystal defects. The double-layer capacitance (C_dl) of the electrolyte/CF₄ plasma-treated boron-doped diamond interface was found to show a minimum value at 1 min of treatment. These results indicate that a short-duration CF₄ plasma treatment is effective for the fabrication of fluorine-terminated diamond surfaces without undesirable surface damage.     

Effectiveness of spatial representation in the formation of network communities: experimental study on community organizer

In this paper, we present and discuss Community Organizer, a system designed to support network communities. The main characteristic of Community Organizer is the use of spatial representations for the relationships among community members including the communications exchanged among these members. These spatial representations reflect the degree of closeness of interests and concerns among the members, and are intended to provide users with clues on how to form network communities. In order to investigate the effectiveness of the proposed spatial representations, we conducted experiments with two different versions of the software. One version offered meaningful spatial representations while the other version did not. The subjects who used the former software version felt a greater sense of ‘community’, enjoyed using the software more, and actively used it longer than the subjects using the latter software version (control condition). These results indicated that the proposed spatial representations are effective in supporting network community formation.     

Formation and Characterization of Ce3ZrO8 Prepared by the Hydrazine Method

A compound denoted as (Ce_0.75Zr_0.25)O₂ (Ce, ZrO₈) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C.     

Hydrothermal Synthesis and Low-Temperature Sintering of Zinc Gallate Spinel Fine Particles

Nanosized powders of single-phase zinc gallate (ZnGa₂O₄) spinel were hydrothermally synthesized from solutions in the presence of NaOH over the pH range of 1.9 to 7.0 and from solutions above pH 7.0, i.e., the very basic medium (pH of 13.85), by removing the residual ZnO phase by washing with aqueous H₂SO₄ from the precipitate mixtures of zinc gallate spinel particles and ZnO. A very wide compositional range (Zn/2Ga = 0.705–1.157) of zinc gallate spinel solid solutions could be hydrothermally synthesized in the form of nanosized particles from acid and very basic mediums (pH of 2.4–13.85) in the presence of NaOH. These hydrothermally synthesized spinel powders showed good sinterability and almost full densification at 1100°C for 1 h. Dense sintered bodies consisting of single-phase zinc gallate spinel were fabricated at 1100°C using zinc gallate spinel powders having almost stoichiometric composition formed from the solution at pH 9.95 in the presence of aqueous ammonia.     

Concentration of docosahexaenoic acid in glyceride by hydrolysis of fish oil withcandida cylindracea lipase

In an attempt to concentrate the content of DHA (docosahexaenoic acid) in a glyceride mixture containing triglyceride, diglyceride and monoglyceride, fish oil was hydrolyzed with six kinds of microbial lipase. After the hydrolysis, free fatty acid was removed and fatty acid components of the glyceride mixtures were analyzed. When the hydrolysis withCandida cylindracea lipase was 70% complete, the DHA content in the glyceride mixture was three times more than that in the original fish oil. The EPA (eicosapentaenoic acid) content became almost 70% of the original fish oil. Hydrolysis with other lipases did not result in an increase in the DHA content in the glyceride mixtures. Hydrolysis of DHA-rich tuna oil (DHA content is about 25%) withCandida cylindracea lipase resulted in 53% DHA in the glyceride mixture. The EPA content, however, remained close to that of the original tuna oil. In this report, the acyl chain specificity of lipases is evaluated in terms of hydrolysis resistant value (HRV). HRV is the ratio between the DHA contents in the glyceride mixture of hydrolyzed oil and original oil. HRV clearly indicates differences in hydrolysis between DHA and other fatty acids (e.g., saturated and monoenoic acids).     

Dural caroticocavernous fistula with both ophthalmic arteries arising from middle meningeal arteries

A 60-year-old woman presented with a dural caroticocavernous fistula (CCF) in whom both by ophthalmic arteries arose from the middle meningeal arteries instead of from the internal carotid arteries. Transarterial embolisation of the CCF was contraindicated because of the risk of blindness. Transvenous coil embolisation was therefore performed. Bilateral origin of the ophthalmic artery from the middle meningeal artery is extremely rare.     

Effects of cytogenin on spontaneous arthritis in MRL/1 mice and on pristane-induced arthritis (PIA) in DBA/1J mice

Cytogenin, 8-hydroxy-3-hydroxymethyl-6-methoxyisocoumarin, has low cytotoxicity on murine and human tumour cells in vitro. It augments or suppresses phagocytosis of macrophages and lymphocyte proliferation. It has been reported that cytogenin has a potent inhibitory effect clinically on adjuvant arthritis in Lewis rats and on type II collagen-induced arthritis in DBA/1J mice. Our experimental findings provide evidence that cytogenin has beneficial effects on spontaneous polyarthritis in MRL/1 mice and pristane-induced arthritis in DBA/1J mice. The results suggest that the mode of the anti-arthritic action of cytogenin is different from those of NSAIDs; although the precise mode of action remains unclear, cytogenin may become an excellent therapeutic agent for rheumatoid arthritis.