Synthesis and electrode performance of layered nickel dioxide containing alkaline ions

Several polymorphs of layered nickel dioxide were prepared by using the chemical insertion of alkaline ions into Li_0.10NiO₂. We used aqueous AOH (A = Li, Na, K) solutions as reducing agents. Sodium and potassium insertion resulted in hydrated layered compounds that can be classified as γ-NiOOH with high crystallinity, while lithium insertion occurred without hydration. We discuss the coordination environment around the A⁺ ions for these inserted compounds. The thermal behavior, analyzed using high temperature (HT) X-ray diffraction (XRD) and thermogravimetric (TG) measurements, indicated that heating the hydrate at 150 °C yielded its dehydrate. The electrode performance of the nickelate was studied in lithium cells. We discuss the effect of interlayer water on cell rechargeability and the similarity between these nickelate and hydrated manganese dioxide (birnessite).     

Multiple uses of Essential Oil and By-Products from Various Parts of the Yakushima Native Cedar (Cryptomeria Japonica)

This article presents multiple potential uses of the Yakushima native cedar (Cryptomeria japonica), known in Japan as the Yaku-sugi tree. The Yaku-sugi was divided into four parts: leaves, branches with leaves, branches, and stems. We obtained the essential oil, hydrosol, distillation residue, and distillation wastewater from the trees. Essential oil and hydrosol were determined to be volatile organic compounds. All samples were screened for the following bioactivities: antioxidative, antibacterial, and anti-melanogenesis activities. Freeze-dried distillation residue was tested to assess whether it had a deodorizing effect. The main component of the leaf essential oil was found to be monoterpenes. In contrast, the stem essential oil mainly contained sesquiterpenes. In terms of bioactivities, the leaf essential oil showed antibacterial activity and the stem essential oil showed anti-melanogenesis activity. Distillation residue and wastewater showed many activities, including antioxidant, antibacterial, and anti-melanogenesis activities. Moreover, the residue had a deodorizing effect against ammonia.     

Correlations of Hepatic Hemodynamics,Liver Function,and Fibrosis Markers in Nonalcoholic Fatty Liver Disease: Comparison with Chronic Hepatitis Related to Hepatitis C Virus

The progression of chronic liver disease differs by etiology. The aim of this study was to elucidate the difference in disease progression between chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) by means of fibrosis markers, liver function, and hepatic tissue blood flow (TBF). Xenon computed tomography (Xe-CT) was performed in 139 patients with NAFLD and 152 patients with CHC (including liver cirrhosis (LC)). The cutoff values for fibrosis markers were compared between NAFLD and CHC, and correlations between hepatic TBF and liver function tests were examined at each fibrosis stage. The cutoff values for detection of the advanced fibrosis stage were lower in NAFLD than in CHC. Although portal venous TBF (PVTBF) correlated with liver function tests, PVTBF in initial LC caused by nonalcoholic steatohepatitis (NASH-LC) was significantly lower than that in hepatitis C virus (C-LC) (p = 0.014). Conversely, the liver function tests in NASH-LC were higher than those in C-LC (p < 0.05). It is important to recognize the difference between NAFLD and CHC. We concluded that changes in hepatic blood flow occurred during the earliest stage of hepatic fibrosis in patients with NAFLD; therefore, patients with NAFLD need to be followed carefully.     

The initial step of the thermal unfolding of 3-isopropylmalate dehydrogenase detected by the temperature-jump Laue method

A temperature-jump (T-jump) time-resolved X-ray crystallographictechnique using the Laue method was developed to detect small,localized structural changes of proteins in crystals exposedto a temperature increase induced by laser irradiation. In achimeric protein between thermophilic and mesophilic 3-isopropylmalatedehydrogenases (2T2M6T), the initial structural change uponT-jump to a denaturing temperature (~90°C) was found tobe localized at a region which includes a ß-turn and aloop located between the two domains of the enzyme. A mutant,2T2M6T-E110P/S111G/S113E, having amino acid replacements inthis ß-turn region with the corresponding residues ofthe thermophilic enzyme, showed greater stability than the originalchimera (increase of T_m by ~10°C) and no T-jump-inducedstructural change in this region was detected by our method.These results indicate that thermal unfolding of the originalchimeric enzyme, 2T2M6T, is triggered in this ß-turn region.     

Effect of Moisture on the High-Temperature Stability of Unidirectionally Solidified Al2O3/YAG Eutectic Composites

The corrosion resistance of a unidirectionally solidified alumina/yttrium aluminum garnet (Al₂O₃/YAG) eutectic mixture was investigated at high temperature. Samples were exposed to high temperature (1200°–1800°C) in different atmospheres, which included argon, argon/water vapor, air, and air/water vapor. The most important microstructural changes occurred at the interface between the YAG and the Al₂O₃. Those changes consisted of localized thermal grooving, especially when the corrosive atmosphere contained water vapor. The samples exhibited significant weight loss at high temperature (1800°C) after 20 h of exposure. The calculated volume gain that was induced by the increased surface relief was low and limited, except when the corrosive atmosphere contained air, which indicated that the presence of air (particularly oxygen) induced a more-active corrosion process. On the other hand, no change in the flexural strength was observed, even after 100 h at 1800°C in a humid atmosphere, because of the cross-linked structure of the composite, which limited propagation of the groove.     

Polystyrene with half-titanocene/MAO catalysts: Influence of 2,6-diisopropylphenol

Styrene polymerization was carried out by a simple half-titanocene complex [cyclopentadienyltitanium trichloride] (CpTiCl₃) and pentamethyl [cyclopentadienyltitanium trichloride] (Cp*TiCl₃) combined with methylaluminoxane (MAO) as a cocatalyst. The effects of addition of 2,6-diisopropylphenol on the catalytic activity of the above catalytic systems and the microstructure of the resulting polymer were investigated. The results of the above experiments showed that the addition of the 2,6-diisopropylphenol changed the catalytic performance of the above catalytic systems, in terms of catalytic activity of the metal complexes and microstructure, molecular weight and molecular weight distribution of polystyrene synthesized. The yields of polystyrene of the above polymerization reactions indicated that the 2,6-diisopropylphenol enhanced the catalytic activity of both the CpTiCl₃/MAO and Cp*TiCl₃/MAO catalyst systems. Further Soxhlet extraction of the polymer was conducted by boiling acetone for 6 h to get pure syndiotactic polystyrene. The microstructure of polystyrene obtained by the above polymerization reactions was investigated by ¹³C NMR, GPC and DSC. Results indicated the formation of syndiotactic polystyrene in the absence of phenol and in low concentration of phenol. On the other hand, in the presence of excess phenol, the polystyrene produced was found to be completely atactic in nature. The appearance of monomodal peaks and narrow polydispersity in the GPC results of polystyrenes obtained in all the above polymerizations indicated that the polymerization was only coordination in nature.     

SCR of NOx with NH3 over Cu/NaZSM-5 and Cu/HZSM-5 in the presence of decane

The selective catalytic reduction of NO_x with NH₃ in the presence of decane over Cu/ZSM-5 catalysts prepared from H⁺ and Na⁺ZSM-5 precursors were investigated. Cu/NaZSM-5 catalyst showed significantly higher NO_x conversion compared to Cu/HZSM-5. However, the presence of decane decreased the activity of both the catalysts, due to coke formation. Cu/HZSM-5 catalyst showed a larger decline in NO_x conversion with time on stream compared to Cu/NaZSM-5. The higher activity of Cu/NaZSM-5 is attributed, to the promoting effect of Na⁺ cations in the formation of active Cu⁺ and nitrite and nitrate intermediates species and retardation of coke formation.     

Freezing step controls the mannitol phase composition heterogeneity

Freeze-dried samples were prepared from D-mannitol solution by selected freezing conditions. Crystalline structures of prepared samples were determined by XRD analysis, and distributions of the various crystal structures of mannitol were obtained for each sample. It was found that the amount of each polymorph was quite well correlated to the freezing conditions, namely the ice crystal nucleation temperature and the cooling rate. In case of samples prepared at fast cooling rates, the samples where the ice crystals nucleated at higher temperature contained much more stable form than the samples nucleated at lower temperature. Besides, the samples prepared at slow cooling rates predominantly contained stable crystalline forms despite of the variation of nucleation temperatures. Moreover, the experimental results also indicated that the various polymorphs were also distributed vertically through the sample along the direction of the heat flux during freezing. The tendency of the polymorph distribution through the freeze-dried cake was also elucidated by using the simulated temperature profiles during freezing. Thus, the profiles of mannitol polymorphs after the freezing derived from the temperature distributions could predict the global tendency of polymorphism behaviour, and, consequently, would be useful to achieve quality control of freeze-dried formulations.     

Electron spin resonance investigation of small spin probes in aqueous and vesicle phases of mixed membranes made from poly(oxyethylene) hydrogenated castor oil and hexadecane

Small spin probes in the vesicle and aqueous phases of mixed membranes made from poly(oxyethylene) hydrogenated castor oil (HCO) and hexadecane were investigated by ESR (electron spin resonance) spectroscopy. Partitioning (partition coefficients), rotational correlation times, and activation energies of the spin probes in the vesicle phase were determined. The quantitative results obtained by an ESR simulation indicated that the spin probe DTBN (di-tert-butyl nitroxide), in the vesicle of the mixed membrane, was partitioned similar to that of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) at 50 degrees C, and the partitioning for both probes showed no abrupt change across the temperatures examined. The results differed considerably from conventional analyses of the high-field signal intensities. Activation energies obtained by the simulation for DTBN and TEMPO were 21 and 20 kJ/mol, respectively. In addition, the hyperfine values of 15.8 (DTBN) and 16.1 G (TEMPO) in the vesicle phase were consistent with the activation energies and supported the probe environments in the membrane. Thus, the present ESR results provided detailed information regarding the probe behavior in the membrane.     

Microstructural characteristics of tungsten-base nanocomposites produced from micropowders by high-pressure torsion

Micropowder mixtures of W–50% Al, W–50% Ti and W–50% Ni were subjected to severe plastic deformation at 573 K using high-pressure torsion (HPT). The powder mixtures were consolidated and nanocomposites of W/Ti, W/Ti and W/Ni, with average grain sizes as small as ～9, ～15 and ～12 nm, respectively, were formed by imposing large shear strains. The nanocomposites exhibited Vickers microhardness as high as ～900 Hv, a level that has rarely been reported for metal–matrix composites. X-ray diffraction analyses together with high-resolution transmission electron microscopy showed that in addition to grain refinement, an increase in the fraction of grain boundaries up to 20%, the dissolution of elements in each other up to ～15 mol.%, an increase in the lattice strain up to 0.6%, and an increase in density of edge dislocations up to 10¹⁶ m^?2 occurred by HPT. The current study introduces the HPT process as an effective route for the production of ultrahigh-strength W-base nanocomposites, fabrication of which is not generally easy when processing at high temperatures because of interfacial reaction and formation of brittle intermetallics.