Relation between crystal structure and lattice oxygen content of sintered reaction-bonded silicon nitride

When reaction-bonded silicon nitride containing MgO/Y₂O₃ additives is sintered at three different temperatures to form sintered reaction-bonded silicon nitride (SRBSN), the thermal conductivity increases with sintering temperature. The β-Si₃N₄ (silicon nitride) crystals of SRBSN ceramics were synthesized and characterized to investigate the relation between the crystal structure and the lattice oxygen content. The hot-gas extraction measurement result and the crystal structure obtained using Rietveld analysis suggested that the unit cell size of the β-Si₃N₄ crystal increases with the decrease in the lattice oxygen content. This result is reasonable considering that the lattice oxygen with the smaller covalent radius substitutes nitrogen with the larger one in the β-Si₃N₄ crystals. The lattice oxygen content decreased with increasing sintering temperature which also correlated with increase in thermal conductivity. Moreover, it is noteworthy from the viewpoint that it may be possible to apply the lattice constant analysis for the nondestructive and simple measurement of the lattice oxygen content that deteriorates the thermal conductivity of the β-Si₃N₄ ceramics.     

1H NMR,thermal, and conductivity studies on PVAc based gel polymer electrolytes

The lithium‐ion conducting gel polymer electrolytes (GPE), PVAc‐DMF‐LiClO₄ of various compositions have been prepared by solution casting technique. ¹H NMR results reveal the existence of DMF in the gel polymer electrolytes at ambient temperature. Structure and surface morphology characterization have been studied by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM) measurements. Thermal and conductivity behavior of polymer‐ and plasticizer‐salt complexes have been studied by differential scanning calorimetry (DSC), TG/DTA, and impedance spectroscopy results. XRD and SEM analyses indicate the amorphous nature of the gel polymer‐salt complex. DSC measurements show a decrease in T_g with the increase in DMF concentrations. The thermal stability of the PVAc : DMF : LiClO₄ gel polymer electrolytes has been found to be in the range of (30–60°C). The dc conductivity of gel polymer electrolytes, obtained from impedance spectra, has been found to vary between 7.6 × 10^?7 and 4.1 × 10^?4 S cm^?1 at 303 K depending on the concentration of DMF (10–20 wt %) in the polymer electrolytes. The temperature dependence of conductivity of the polymer electrolyte complexes appears to obey the VTF behavior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Selective catalytic reduction of nitrogen oxides with hydrocarbons over Zn–Al–Ga complex oxides

Selective reduction of NO with hydrocarbons was studied using metal oxide catalysts having a spinel structure. A Zn–Al–Ga complex oxide was found to be very active and selective for the catalytic reduction of NO with both C₃H₆ and CH₄. It was revealed that the role of oxygen at the initial stage of the reaction strongly depends on the reductants; oxygen is mainly used for NO oxidation to NO₂ in the reduction with CH₄, whereas it is used both for NO oxidation to NO₂ and oxidation of C₃H₆ to an active intermediate in the reduction with C₃H₆. This revised version was published online in July 2006 with corrections to the Cover Date.     

A study on the preparation of supported metal oxide catalysts using JRC-reference catalysts. I. Preparation of a molybdena–alumina catalyst. Part 4. Preparation parameters and impact index

The effects of the volume and pH of the impregnation solution and of the calcination conditions were examined on the physicochemical and catalytic properties of a 13 wt% MoO₃/Al₂O₃ extrudate catalyst. The Al₂O₃ support and drying procedures (static conditions without flowing air) were fixed in the preparations. In the present series of catalysts, the amount of crystalline MoO₃ was marginally small. It was found that the dispersion of Mo oxide species increased as the volume of the impregnation solution increased, gradually approaching a maximum value. The increase in pH (2–8) of the impregnation solution was found to reduce the dispersion of Mo oxide species. The Mo dispersion increased slightly for the impregnation catalysts as the calcination temperature increased (673–873 K), whereas it decreased for the equilibrium adsorption catalysts. The effects of the calcination atmosphere (with or without flowing air, or with flowing humid air) were very small on the dispersion of Mo oxide species under the present preparation conditions. On the other hand, the methanol oxidation activity of MoO₃/Al₂O₃ was sensitive to the preparation parameters examined here. It was demonstrated by means of EPMA and XPS that a considerable migration of Mo took place during the calcination.

In the present study on the preparation of a 13 wt% MoO₃/Al₂O₃ catalyst, an impact index is proposed to measure the magnitude of the effects of the respective parameter(s) on the physicochemical and catalytic properties. With the Mo dispersion, the effects of the preparation parameter decreased in the order, surface area of the support >> drying process > volume of the impregnation solution > pH, calcination temperature and atmosphere. The size of the impact index for the dispersion of Mo sulfide species is 70–75% of that for the Mo oxide species. The HDS activity of the catalyst was less affected by the preparation parameters than the Mo sulfide dispersion. The preparation parameters affected the segregation of Mo on the outer surface of extrudates in a decreasing order: drying process > volume of the impregnation solution > pH, calcination conditions. It was found that the oxidation of methanol was affected most intensely by the drying procedures. The volume of the impregnation solution, calcination conditions and pH of the impregnation solution also strongly affected the oxidation activity. The impact index suggests that the sensitivity to the preparation variables of the physicochemical and catalytic properties of MoO₃/Al₂O₃ decreases in the order, methanol oxidation activity > surface Mo segregation > Mo oxide dispersion > Mo sulfide dispersion > HDS activity.     

Deposition and structural analyses of molybdenum-disulfide (MoS2)–amorphous hydrogenated carbon (a-C:H) composite coatings

In this study we developed composite coatings consisting of amorphous hydrogenated carbon (a-C:H) and molybdenum-disulfide (MoS₂), and clarified their microstructure. In addition, we interpreted the tribological properties of the composite coatings in the viewpoint of a deposition-induced microstructural modification. The coatings were produced by the hybrid deposition technique of RF-generated methane and argon plasma and DC magnetron co-sputtering of MoS₂ target. The deposition parameter investigated in this study was methane flow rate. Structural analyses were performed using a transmission electron microscope (TEM) and an atomic force microscope (AFM). Friction tests were conducted using a ball-on-disk type tribometer. From an electron micrograph, it was confirmed that nano-clusters were embedded into an amorphous carbon host matrix. Surface roughness of the composite coating was ～ 0.25 nm in R_a compared to 5.0 nm in R_a of sputtered MoS₂. The concentration measurements were performed, and the results show that the sulfur and molybdenum concentration ratio, [S]/[Mo], is ～ 0.9, which indicates that the amount of sulfur was reduced due to the discharged plasma. In friction tests, composite coatings showed high friction in a vacuum condition. It was considered that lubricant MoS₂ lamellar structures showing super-low friction in a vacuum condition during friction could not be formed between ball and coating during friction because of the lack of sulfur in embedded clusters.     

Molecular and Genetic Interactions between CCN2 and CCN3 behind Their Yin–Yang Collaboration

Cellular communication network factor (CCN) 2 and 3 are the members of the CCN family that conduct the harmonized development of a variety of tissues and organs under interaction with multiple biomolecules in the microenvironment. Despite their striking structural similarities, these two members show contrastive molecular functions as well as temporospatial emergence in living tissues. Typically, CCN2 promotes cell growth, whereas CCN3 restrains it. Where CCN2 is produced, CCN3 disappears. Nevertheless, these two proteins collaborate together to execute their mission in a yin–yang fashion. The apparent functional counteractions of CCN2 and CCN3 can be ascribed to their direct molecular interaction and interference over the cofactors that are shared by the two. Recent studies have revealed the mutual negative regulation systems between CCN2 and CCN3. Moreover, the simultaneous and bidirectional regulatory system of CCN2 and CCN3 is also being clarified. It is of particular note that these regulations were found to be closely associated with glycolysis, a fundamental procedure of energy metabolism. Here, the molecular interplay and metabolic gene regulation that enable the yin–yang collaboration of CCN2 and CCN3 typically found in cartilage development/regeneration and fibrosis are described.     

Partial oxidation of ethane to synthesis gas over Co-loaded catalysts

Attention has been increasingly paid to the partial oxidation of lower alkanes to synthesis gas, due to its intrinsic energy saving process. We studied the partial oxidation of ethane (POE) on Co loaded on various supports. The POE performance varied as follows: Y₂O₃, CeO₂, ZrO₂, La₂O₃  SiO₂, Al₂O₃, TiO₂ > MgO. Comparing Y₂O₃ and CeO₂, the carbon deposition during the POE was negligible on CeO₂ and therefore CeO₂ was the most preferable support. By changing space velocity and O₂ partial pressure, reaction mechanism of POE was studied and it was revealed that two-step mechanism was prevailing; combustion of ethane to H₂O and CO₂ and subsequent reforming of ethane with H₂O and CO₂ to synthesis gas. Co/CeO₂ catalyst exhibited high and stable catalytic activity for 10 h; high ethane conversion of 18% (maximum ethane conversion 20% at O₂/C₂H₆ = 0.2) with H₂ and CO selectivities of 93 and 84%, respectively.     

Te concentration dependent photoemission and inverse-photoemission study of FeSe1?xTex

We have characterized the electronic structure of FeSe_1−xTe_x for various x values using soft x-ray photoemission spectroscopy (SXPES), high-resolution photoemission spectroscopy (HRPES) and inverse photoemission spectroscopy (IPES). The SXPES valence band spectral shape shows that the 2 eV feature in FeSe, which was ascribed to the lower Hubbard band in previous theoretical studies, becomes less prominent with increasing x. HRPES exhibits systematic x dependence of the structure near the Fermi level (E_F): its splitting near E_F and filling of the pseudogap in FeSe. IPES shows two features, near E_F and approximately 6 eV above E_F; the former may be related to the Fe 3d states hybridized with chalcogenide p states, while the latter may consist of plane-wave-like and Se d components. In the incident electron energy dependence of IPES, the density of states near E_F for FeSe and FeTe has the Fano lineshape characteristic of resonant behavior. These compounds exhibit different resonance profiles, which may reflect the differences in their electronic structures. By combining the PES and IPES data the on-site Coulomb energy was estimated at 3.5 eV for FeSe.     

The evaluation of the emotion by near-infrared spectroscopy

Our purpose is to develop the technology for evaluating emotion objectively from the oxygenated hemoglobin within a brain. Nowadays, Japan is an aging society. The elderly people who need care will increase from now on increasingly. In the case of the person requiring the care who lost the function to convey an intention especially, the objective judgment to a physical and mental pain is required. Persons requiring care will also increase in number with the increase in this population. We gave subject stimulus of a comfortable or an uncomfortable sound and measured concentration of the oxygenated hemoglobin of a frontal lobe part by near-infrared spectroscopy. Based on the experimental result, a comfortable state or an uncomfortable state was distinguished by concentration of the oxygenated hemoglobin using the bayesian network. As a result, we were able to estimate the subject’s psychological condition.     

Simultaneous Quantification of Secoisolariciresinol Diglucoside and Cyanogenic Glycosides in Flaxseed Products by Various Processing Methods

Two cyanogenic glycosides (linustatin and neolinustatin) and sucrose were isolated from defatted flaxseed, and their structures were determined by NMR spectral analysis and comparison with existing data. Using secoisolariciresinol diglucoside (SDG) and the cyanogenic glycosides as standards, we developed a method to quantify the three compounds simultaneously by ultrahigh-performance liquid chromatography (UHPLC)-MS in selected reaction monitoring (SRM) mode. Using this tool, flaxseed powder—processed by various methods—was analyzed with regard to the contents of the beneficial compound, SDG, and the toxic compounds, cyanogenic glycosides. The levels of SDG in samples treated with alkaline solution are much higher than in samples without treatment, and in general, the levels of linustatin and neolinustatin in flaxseed powder decreased progressively as heating time is prolonged after treatment with alkaline solutions.