Search

CeO2 shows unique catalytic properties by an acid–base bifunctionality as well as redox properties. The acid–base bifunctional properties of CeO2 have been applied to the non-reductive CO2 conversion with alcohols such as dimethyl carbonate (DMC) synthesis from CO2 and methanol. CeO2 shows very high selectivity to DMC; however, the yield of DMC is strongly limited by the equilibrium. The combination of the synthesis of organic carbonates from CO2 and corresponding alcohols with suitable H2O removal methods can enhance the yield of the organic carbonates beyond the equilibrium limitation. Many CeO2-based materials have been prepared and tested in the reaction of CO2 with alcohols. As is known, what catalysts can do is to make the reactions progress to the equilibrium level in reversible reactions and the catalysts do not influence the equilibrium level and thermodynamics of the reactions. In order to evaluate the catalytic properties of CeO2-based materials in this reaction, we should pay more attention to the catalytic activity. In addition, the catalytic activity should be measured under the reaction conditions at a sufficiently lower conversion level than that at the equilibrium level, because the effect of the reverse reaction can be neglected. The catalytic performance of the CeO2-based materials is compared considering the equilibrium level under the reaction conditions. Morphology, oxide ion defects (or oxygen vacancies), as well as acid–base properties on the catalytic performance can influence the catalytic activity; however, it seems to be difficult to elucidate crucial factors. Therefore, development of CeO2-based materials with much higher catalytic activities than reported results is necessary, which will contribute to the determination of the most crucial factor.

It has been difficult to prepare Y123 films with a thick ness greater than 400 nm by using a single coating-preflring procedure in metal organic deposition (MOD), since shrinkage of the film causes cracks in the pyrolysis process. In the present study, we developed a novel coating solution for crack-free films with thicknesses greater than 500 nm. We used a Y-, Ba-, and Cu-acetylacetonate-based solution (metal content: ~2mol metal/L) with various additives for the coating solution. We prepared prefired films on CeO2-buffered YSZ (CbYSZ) or CeO2-buffered SrTiO3 (CbSTO) substrates using the single coating-preflring process and this solution. When using some additives, we could obtain crack-free preflred films with thicknesses corresponding to 350-800 nm after crystallization to Y123. These prefired films were heat-treated at high-temperatures, resulted in epitaxial Y123 films. The Jc and Ic of the film on CbSTO was ~2.3 MA/cm2 and 143 A/cm, respectively.

The performance of a microcombustor thermoelectric generator device based on a thermopile using p-type Bi0.3Sb1.7Te3 (BST) and n-type Pt films has been investigated. The BST films were prepared by two different methods—pulsed laser deposition (PLD) and sputter deposition—on Si3N4/SiO2 multilayers on Si substrate. The ceramic catalyst combustor was patterned on the thermopile end on a thin membrane fabricated by back-side bulk etching of the silicon substrate. At 138°C the thermoelectric power factors of the PLD and sputter-deposited films were 3.6 × 10−3 W/mK2 and 0.22 × 10−3 W/mK2, respectively. The power from the generator with the sputter-deposited film was 0.343 μW, which was superior to that of the device with the PLD film, which provided 0.1 μW, for combustion of a 200 sccm flow of 3 v/v% hydrogen in air.

The effect of water on polymer electrolyte fuel cell degradation was examined with humidity as a parameter. Polymer electrolyte fuel cells were subjected to long-term operation of 10 000 h to examine the relation between decline in cell voltage and degradation of the catalyst layers or gas diffusion layers. The diffusion overpotential increased during long-term operation at relatively high humidification of 81% RH, but only in the catalyst layer and not in the gas diffusion layer. At low humidification of 52% RH, the increase in diffusion overpotential was small, indicating that the increase was more likely to occur under high humidification. Post-analysis of the catalyst layer revealed that the membrane electrode assembly had increased diffusion overpotential during operation under high humidification, as a result of the sharp decline in porosity. The increase of diffusion overpotential in the catalyst layer was also investigated by the observation of the degradation due to the oxidation of the Pt–carbon supports. However, it was found that the oxidation of carbon support which had increased diffusion overpotential was small.

The reinvestigation of the affinity chromatographic method of purifying papain has been carried out. It has been reported that papain could be purified by taking advantage of the affinity of the enzyme for the insolubilized peptide inhibitor, agarose-Gly-Gly-Tyr(Bz)-Arg. Using pure tetrapeptide obtained commercially and standard coupling procedures, a significant purification of papain could not be achieved. Both active and nonactivatible enzyme bound to a column prepared in this manner were eluted together by the use of deionized water. An affinity medium with properties similar to those reported by Blumberg et al. was obtained by removal of the benzyl group on tyrosine prior to coupling with agarose. The deprotected tetrapeptide was also synthesized by an independent route and inhibition constants for the binding of the protected and deprotected tetrapeptide to papain were determined in kinetic experiments.

Two series of activated carbon discs have been prepared by chemical activation of olive stones with ZnCl 2 and H 3 PO 4 . Some of the carbons have been post-treated in order to modify their porous texture and/or surface chemical composition. All carbons have been characterized by adsorption of N 2 (−196 °C) and CO 2 (0 °C) and immersion calorimetry into dichloromethane. The volume of methane adsorbed at 25 °C and 3.5 MPa is proportional to the surface area deduced from immersion calorimetry into dichloromethane. Consequently, it is possible to estimate, using a single experiment, the possibility of using activated carbons for the storage of natural gas. On the other hand, the methane uptake can be also correlated to the volume of micropores, provided by the adsorption of N 2 at −196 °C and CO 2 at 0 °C, although the correlations is not as good. Only carbons slightly activated, with low surface area and microporosity below around 0.6 nm, do not adjust the above correlations because they adsorb more methane than the expected, the effect of chemical nature of the carbon surface being almost negligible.

The microporosity of granular and disc-shaped activated carbons prepared by both ZnCl 2 and H 3 PO 4 activation has been evaluated by adsorption of nitrogen at −196 °C and immersion calorimetry into liquids of different molecular dimensions (dichloromethane, benzene, 2,2-dimethylbutane, carbon tetrachloride and α-pinene). Experimental results show that immersion calorimetry into dichloromethane provides values of surface area more similar to nitrogen adsorption (BET equation) than benzene. No such effect is found for physically activated carbon. Some apparent anomalies have also been detected for the enthalpy of immersion of carbons activated with H 3 PO 4 into α-pinene due to a small amount of phosphorous remaining in the carbon after washing. This is not the case for carbons activated with ZnCl 2 , because the washing was more effective in the removal of the chemical.

Nondestructive, ac inductive methods are widely used to measure critical current densities Jc of large-area superconducting films. However, conventional methods are not accurate because they have not considered the electric-field E criterion of the Jc measurement. In these methods, ac magnetic fields are generated with ac currents Io cos wt in a small coil mounted just above the film. Jc is calculated from the threshold coil current Ith, at which full penetration of magnetic field is achieved. We recently estimated the induced electric fields in the superconducting film at Io = Ith, which are proportional to the frequency, and proposed a method to determine the E - J characteristics by measuring Ith at various frequencies. In this paper we propose a standard method to precisely measure Jc with an electric-field criterion by detecting third-harmonic voltages. We also demonstrate a machine that can automatically measure the distribution of Jc and the n-values of the power-law E - J characteristics. We show several examples of measurements of co-evaporated YBCO films and low-cost metal organic deposition YBCO films, which were used in switching experiments for resistive fault-current limiters.

We have been investigating a superconducting fault current limiter (FCL), in which YBCO superconducting thin films with Au-Ag alloy shunt layers are used. The ability of the films to withstand high electric fields (> 40 Vpeak/cm) enables the total length of FCL elements to be reduced, thus greatly reducing the cost of FCLs. In this paper, we report the temperature characteristics of Au-Ag/YBCO composite films with sapphire substrates. Temperature of the film was estimated as average temperature from voltage and current in the films during the over-current period of 0.1 s using the relation between their resistance and temperature. The effect of thickness of the substrate was examined. Temperature data were analysed with the relation between the maximum temperature and joule heating during the over-current period. Data on recovery time are also shown.

Microcrack-free thick YBa2Cu3O7-delta (YBCO) films were successfully fabricated by pulsed laser deposition on deliberately miscut AI2O3 (1102) (5.22deg off towards [1102]) buffered with CeO2. Characterization of the films revealed a porous morphology, consisting of interconnected islands and deep holes (pores). The microstructure of the YBCO films was further investigated by cross-section (cut along both AI2O3 [1101] and [1120] transmission electron microscopy (TEM). No apparent interface reaction is seen for all the TEM observations. A high density of linear defects aligned near c-axis are frequently observed. All the defects are initiated from the YBCO / CeO2 interface, indicating the importance of the microstructure of the CeO2 buffer layer and the sapphire substrate for the growth of YBCO. In addition, numerous small stacking faults lying in the alpha - b-plane of YBCO were produced by the linear defects. The high density of the growth-induced defects may act as strong pinning centers in YBCO films and therefore increase Jc of the film.

Two series of activated carbon monoliths (discs) have been prepared by chemical activation of olive stones with phosphoric acid or zinc chloride, without the use of any binder. A conforming step was introduced between impregnation with the chemical and heat treatment. Two equivalent series of granular activated carbons were also prepared in order to analyse the effect of conforming pressure on the porosity of the final activated carbon. The evolution of microporosity and the micropore size distribution has been followed by gas adsorption (N2 at −196 °C and CO2 at 0 °C) and immersion calorimetry into three liquids with different molecular dimensions (dichloromethane, benzene and 2,2-dimethylbutane). The experimental results indicate that activation by both chemicals produces a large development of microporosity but the differences between the granular and monolithic forms are more noticeable when using phosphoric acid. Thus, there is mainly a reduction in the interparticle space and macroporosity during the formation of the discs prepared using zinc chloride whereas there is an additional reduction in the volume and dimension of the meso- and microporosity when using phosphoric acid. The different behaviour of the two chemicals has been related to their effect on the precursor along the impregnation step. Authors acknowledge the financial support from MEC (The project MAT2004-03480-C02-02).

Starch was hydrothermally degraded without any additives over the temperature range from 453 to 563 K at a constant pressure of 10 MPa and the fluid residence times up to 6 min in a semi-batch reactor to produce glucose and maltooligosaccharides. The effects of reaction temperature, flow rate of hot water and residence time of water-soluble components on the product distribution in the solvothermal degradation of starch were investigated. Even at the lowest reaction temperature studied, the loaded starch was partially degraded and dissolved within 8 min by contacting high-temperature and high-pressure water in a semi-batch reactor. By installing a plug-flow reactor at the exit of the first reactor to increase and control precisely the residence time, the maximum glucose yield of 43.8% on the carbon weight basis of the starting material was obtained at 3.64 min and 513 K. The comparison of yields of glucose and 5-hydroxymethyl furfural (HMF), which is a major secondary product, indicates that adjusting the residence time was the most effective to increase the glucose yield and to suppress the 5-HMF production.

YBCO films deposited from a stoichiometric (Y123) target via a large-area PLD system have consistently been found to be Y-rich in composition as well as characterized by pores. Use of an off-stoichiometric target with increased Ba and Cu content proved to be an effective method to compensate for the deficiency in barium and copper in the films. Films with composition closer to the ideal stoichiometric ratio have been obtained from the off-stoichiometric target, including significantly reduced pore density, improved microstructure and higher critical current density ( J c ) in excess of 2 MA/cm 2 at 77.3 K over a 2 ″ -diameter area. Furthermore, it was found out that the dense and smooth YBCO film deposited from the off-stoichiometric target needed ex situ oxygen annealing to reach fully-oxygenated state.

The surface morphology of YBCO films deposited by a large-area PLD system is characterized by pores of varying depths and sizes. The presence of these pores has been correlated to the yttrium-rich composition in the films. In-depth studies on the interplay of parameters including oxygen background pressure, target–substrate distance, film composition, and target stoichiometry on the porosity of the YBCO films deposited on LAO (100) substrates have been conducted. Off-stoichiometry in the composition of the films has been attributed to the scattering of the ablated species with the oxygen ambient. The relative excess of yttrium in the films causes the segregation of yttrium-rich secondary phases, one of which has been identified for the first time as barium yttrium oxide (BaY2O4). From structural characterizations, it has been found that the nucleation and enlargement of the barium yttrium oxide phase obstructs the YBCO growth and eventually causes the pores in the film to develop. Considering the deposition conditions which either promote or hinder the formation of this secondary phase during YBCO growth, a reasonably good control of pore size and density has been achieved.

Contamination by endotoxin of nine kinds of wound dressings made of natural biomaterials (calcium alginate, collagen, chitin, and poly-L-leucine) was examined with the use of water extracts. By applying the Limulus amoebocyte lysate (LAL) test, high concentrations of endotoxin were detected in extracts from three kinds of products made of calcium alginate. These extracts evoked fever in rabbits and induced the release of a proinflammatory (pyrogenic) cytokine, interleukin-6 (IL-6), from human monocytic cells (MM6-CA8). The effects disappeared when the extracts were treated with endotoxin-removing gel column chromatography or with an endotoxin antagonist, B464, confirming that the contaminating pyrogen was endotoxin. A noteworthy finding was that one of the endotoxin-containing extracts showed very weak IL-6-inducibility in human monocytic cells in contrast to its high pyrogenicity to rabbits. The discrepancy could be explained based on differences between humans and rabbits in sensitivity to the endotoxin, because the extract showed higher proinflammatory-cytokine (TNF-alpha)-inducibility in rabbit whole-blood cells (WBCs) than human WBCs. The results suggest that the LAL test is a useful method of detecting endotoxin contamination in wound dressings and the MM6-CA8 assay is a good supplement to the LAL test for evaluating pyrogenicity in humans accurately.

1. The metabolites of bisphenol A (BPA; 2,2-bis(4-hydroxyphenyl)propane) in freshly isolated rat hepatocytes and the oestrogenic activities of BPA and its metabolites, particularly 3-hydroxybisphenol A (3-OH-BPA), in MCF-7 cells and competitive binding assays have been studied, respectively. 2. During a 2-h incubation, almost all of the BPA (0.25 mM) added to the hepatocyte suspensions was rapidly converted to a major conjugate, monoglucuronide (approximately 75% of total metabolites), and two minor conjugates, which were tentatively identified as monosulphates of BPA and a hydroxylated intermediate, 3-OH-BPA, as determined by mass spectroscopy coupled with HPLC or GC/MS. On the other hand, free 3-OH-BPA was identified as a trace metabolite, whose level was approximately 1 or 2 microM at 1 h in hepatocyte suspensions treated with 0.25 or 0.5 mM BPA, respectively. 3. In another experiment, 3-OH-BPA as well as BPA displaced competitively 17beta-oestradiol bound to the recombinant human oestrogen receptor alpha in a concentration dependent-manner: IC50 of diethylstilbestrol, BPA and 3-OH-BPA were approximately 2.5 x 10(-8), 10(-5) and 5 x 10(-5) M, respectively. Further, BPA and 3-OH-BPA at intermediate concentrations (10(-7) - 10(-6) M) caused proliferation of MCF-7 human breast cancer cells, whereas the effect of BPA was more potent than that of 3-OH-BPA. At higher concentrations, both BPA (10(-4)) and 3-OH-BPA (10(-5) M) were cytotoxic. 4. Based on the proliferative potency in MCF-7 cells and the IC50 for the competitive binding, the oestrogenic activity of 3-OH-BPA was less than that of BPA. These results indicate that BPA itself rather than its metabolite acts as a xeno-oestrogen and that 3-OH-BPA is cytotoxic, possibly acting via reactive semiquinone and/or quinone metabolites, rather than a xeno-oestrogenic mechanism, in MCF-7 cells.

To determine the processes and factors responsible for the chemical composition of mountainous stream waters, correlations among solute concentrations in streams were examined in 13 forested watersheds from Japan, Jiulianshan (southern China) and Chiang Mai (northern Thailand), which had different soil parent materials and climatic conditions. The Na+ concentration in stream water was significantly correlated with both Cl− and Si concentrations in the regions near the sea (Kagawa and Shibecha), but was correlated with the Si concentration in the regions far from the sea (Mt. Hiei, Takayama, Jiulianshan and Chiang Mai). In some watersheds in Kagawa, the Si concentration was correlated with Cl−, probably reflecting the relatively dry climate conditions. In Kagawa and Mt. Hiei, SO42− concentrations in stream water were inversely correlated with NO3− concentrations, suggesting that nitrification inhibited SO42− discharge, and denitrification and root NO3− uptake enhanced it. The alkalinity was mainly carried by HCO3− and organic acid anions. According to the theory of ion exchange equilibrium, high alkalinity was closely related to divalent cations (Ca2+ and Mg2+) more than to Na+. In the streams where concentrations of SO42− and divalent cations were low (Chiang Mai), alkalinity was closely related to Na+ reflecting production by weathering.

Cystinuria, an inherited disease, is clinically diagnosed by detecting cystine in urine. A colorimetric method using sodium cyanide and sodium nitroprusside is a simple qualitative test used to detect cystinuria. Several colorimetric methods have been proposed for quantitative analysis of cystine; however, we found that none of them were satisfactory because the results were not reproducible. The causes of non-reproducible results were: (1) insufficient reduction time for conversion of cystine to cysteine, and (2) the interference of creatinine. In this report, we present a method to quantitate cystine in urine. We also found that ascorbic acid and ferric chloride, but not zinc chloride, interfered with the color reaction. Using this method, 15 normal urine samples (10 males and 5 females) and 12 cystine stone forming patients' (5 males and 7 females) urine were analyzed. The method was compared to commercially available urine controls. Only captopril showed a dose dependent response and color intensity at 521 nm. Thiola and D-penicillamine showed little effect on cystine determination.

Very High Frequency (VHF) plasma enhanced chemical vapour deposition (PECVD) has been applied to hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon nitride (a-SiNx:H) films for thin film transistors (TFTs) fabrication. The effect of the excitation frequency on the deposition rate and the film quality of both films has been investigated. The films were prepared by VHF (30 MHz∼50 MHz) and HF (13.56 MHz) plasma enhanced CVD. High deposition rates were achieved in the low pressure region for both a-Si:H and a-SiNx:H depositions by the use of VHF plasma. The maximum deposition rates were 180 nm/min for a-Si:H at 50 MHz and 340 nm/min for a-SiNx:H at 40 MHz. For a-SiNx:H films deposited in VHF plasma, the optical bandgap, the hydrogen content and the [Si–H]/[N–H] ratio remain almost constant regardless of an increase in deposition rate. The increase of film stress could be limited to a lower value even at a high deposition rate. The TFTs fabricated with VHF PECVD a-Si:H and a-SiNx:H films showed applicable field effect mobility. It is concluded that VHF plasma is useful for high rate deposition of a-Si:H and a-SiNx:H films for TFT LCD application.

The morphologies of LB films of arachidic acid and its salt were observed by atomic force microscopy (AFM) to reveal their cation dependence from the viewpoint of ionic radius and solution pH. The salt films having divalent metal ions (Ba 2+ , Sr 2+ and Co 2+ ) except for Mn 2+ showed similar characteristic stripe-shaped macroscopic structures. An area per molecule in the film increased with decrease of ionic radius. Concerning the solution pH, significant changes in molecular arrangements and macroscopic structures were observed in the barium arachidate films. Coexistence of 2×2 superstructures with 1×1 fundamental structures were observed at pH=8.0, but 3×1 at pH=9.8. These structures were considered to depend on the increase of the salt forming ratio increases with pH.

This paper explores the contribution to high silica zeolite syntheses based upon derivatives of a six-ring heterocycle, piperidine. The zeolite product selectivity can be rationalized in terms of the type and location of ring substitution in the derivatives studied as structure-directing agents (SDAs) in zeolite crystal growth. A number of new zeolite products were found as the substitution leads to spatially larger molecules. The pure phase MEL was produced by one very specific SDA. As well as the synthesis studies presented, a select group of derivatives built around the azaspiro [5.5] undecane architecture were also studied as to their hydrophobic transfer from water to chloroform during solvent partitioning studies. One surprising discovery was that a single spiro derivative produced five different zeolite products over a range of synthesis conditions, and these five zeolites were initially encountered in studies with a single adamantyl derivative. Attempts were made via molecular modeling to determine why these two disparate SDAs yield almost the same zeolite product selectivities.

The synergy of template molecule size and hydrophobicity and the sources of inorganic reagents affecting zeolite nucleation are described. In particular, the discovery of high silica zeolites SSZ-26, 41, 42 and UTD-1 is considered in this light. Of particular value is the use of zeolites themselves as reactants; three different examples are given. Some general rules for lattice substitution and zeolite product type are given. An unexpected use of the template used in the discovery of zeolite SSZ-42 is described now that the structure of the zeolite has been resolved, largely from single crystal data. Finally some new synthetic conditions with considerable economic advantage are described for zeolite SSZ-25. Some new questions about the effect of organic cations on solution instability are raised.

Aluminum surface freshly shaven with a steel knife showed significant changes in work functions from 3.25 to 3.60 eV within one day. Successive changes of the work functions were measured in air using the open counter. XPS spectra showed no change fundamentally when the fresh Al surface was exposed to air for 1 min and 24 h. Molecular orbital calculations by use of the DV-X α method predicted an appearance of an additional local density of state near the Fermi edge when an Al Al distance becomes large. Based on the experimental results and calculations, we proposed formation of an interface between an Al matrix and a surface oxide or oxyhydroxide, which has a stress induced density of state. This state appears at the beginning of air exposure and disappears after the lapse of time because such stress is released after rearrangement of surface and interface structures.

Nitrogen biogeochemistry of 24 forested sites in Japan was used in evaluating the status of ‘nitrogen saturation’ for this region. Bulk deposition of inorganic N ranged from 3.5 to 10.5 kg N ha −1 yr −1 and losses in drainage waters ranged from 0.6 to 28 kg N ha −1 yr −1 . Concentrations of NO 3 − in drainage waters during the growing season either remained fairly constant or increased during periods of high precipitation inputs. This pattern is markedly different than that exhibited for most forested watersheds in Europe and North America where during the growing season nitrate concentrations often reach their lowest values. These Japanese sites had high rates of N mineralization as a function of abundant moisture and warm temperatures. Nevertheless, most sites, except those with elevated atmospheric inputs of N, had high levels of nitrogen retention. The general absence of seasonal patterns of NO 3 − concentrations also suggests that this condition cannot be used to evaluate nitrogen saturation in Japanese forests as has been done for some watersheds in North America and Europe.

The concept for conducting hydroformylation reactions by immobilized rhodium complex on solid supports has received considerable attention, as revealed by many recent publications and patents. Among a variety of polymeric supports, including styrene-divinyl benzene copolymers or inorganic compounds functionalized with phosphines or amines, vinyl pyridine copolymer crosslinked with divinylbenzene was used as the primary support in this investigation. Three types of heterogeneous rhodium complex catalysts were prepared and their properties, and activities, selectivities and n/i ratio were studied for hydroformylation of propylene and 1-octene at a temperature of 120–130°C, a pressure of 30–90 Kg/cm 2 , and a H 2 /CO ratio of 1. The results of this study revealed that these novel heterogeneous catalysts were useful for hydroformylation of olefins and have commercial potential.

3,3-Dicyanopropyl vinyl ether (DCPVE), a vinyl ether, was found to be radically polymerized in a moderate yield with di-t-butyl peroxide (DTBP). The polymerization of DCPVE with DTBP was kinetically investigated in methyl benzoate. The polymerization rate (Rp) at 130 °C was expressed by Rp = k[DBPO]0.5[DCPVE]1.9. The overall activation energy of the polymerization was 143 kJ mol . The number-average molecular weight ( M n ) of the resulting poly(DCPVE) was in the range 3000–4200, corresponding to polymerization degrees of 22–32. M n decreased with increasing monomer concentration. The i.r., 1H- and 13C-NMR spectra and the thermal degradation behavior of the radically formed poly(DCPVE) were distinguishably different from those of cationically formed polymer and indicated that the radical polymerization of DCPVE proceeds through an addition-abstraction mechanism. Radical copolymerizations of DCPVE with some vinyl monomers were examined on the basis of monomer reactivity ratios and structures of copolymers. The results indicate that the copolymerizations also involve the addition-abstraction mechanism to a considerable extent.

Absolute configuration of 3-hydroxy fatty acids in serrawettins, surface-active exolipids produced by Serratia marcescens , was elucidated by chiral column high-performance liquid chromatography. 3,5-Dinitroaniline or 3,5-dinitrophenyl urethane derivatives of hydroxy fatty acids were directly prepared from crude hydrolysates of the lipids and eluted separately through chiral columns (Enantio P2 or OA-3100) with specific eluents. In both serrawettin W1 and W2, d -3-hydroxydecanoic acid was determined as a major acyl group accompanied by a minor component d -3-hydroxy-dodecanoic acid. Many mutants defective in the production of serrawettins were isolated through screening by direct colony thin-layer chromatography and examined for altered behavioral phenotypes by various methods including digital analysis of colony patterns. Bacteria on surface environments seem to be living under strong surface tension of the surrounding water, and overcoming such circumstance by collaborative multicellular works and production of biosurfactants. Fractal colony growth of S. marcescens was shown as one such indication disclosing biological roles of the surface-active exolipid.

The effects of serum phosphate level on the formation of incisor dentine were investigated in hypophosphatemic (Hyp) mice fed a diet high in calcium and phosphorus (high Ca/P diet). Feeding a high Ca/P diet for more than 10 days resulted in an increase in the serum phosphate level in Hyp mice to one similar to that of normal mice. Lower incisors were cut transversely at the centre of the length of the incisor, a point that had taken approximately 40 days to be reached from the start of dentine formation in Hyp mice. Transverse views of the incisors showed a triangle-like outline in Hyp mice fed a control diet, while the outline became rounded in Hyp mice fed the high Ca/P diet for more than 40 days. In Hyp mice fed the high Ca/P diet for 40 days interglobular dentine was still observed and fluorescent lines produced by tetracycline showed a diffuse and wavy pattern in incisor dentine; however, interglobular dentine became indistinct and fluorescent lines showed a relatively smooth pattern in the incisor dentine of Hyp mice fed the diet for more than 60 days.

Zeolite synthesis results for the use of a family of related quaternary ammonium derivatives of tricyclodecane hydrocarbons as structure-directing agents are described. The work continues our inter...

Roughening procedures including the early stage of the O 2 + -induced ripple formation of GaAs were studied quantitatively by scanning tunnelling microscopy (STM). Detailed examinations of the beginning of topography development using fast Fourier transform of the STM images revealed that the ripple formation was not caused by any accidental defects, particles or original irregularity on the substrate, but solely by the conditions of the ion beam. A systematic investigation of the rippled GaAs surface produced under various O 2 + bombardment conditions was conducted. The ripple wavelength and the transition depth were almost exactly proportional to E P cos θ, where E P and θ are the energy of the ion beam and the incident angle, respectively. For GaAs, the secondary ion yield transition occurs when the slope of ripples facing the incident O 2 + beam reaches a saturation angle of 20-30° from the macroscopic surface plane. Topography change on other III-V semiconductors was also examined for comparison. There was no ripple generation observed for GaP; InP gave a ripple-like structure without secondary ion yield change. A relatively rough surface resulted on GaSb and InAs at a much shallower depth than for GaAs. Rippling and ion yield changes during depth profiling have been suppressed successfully by sample rotation even in a magnetic sector-based instrument.

This reports presents the changing morphological characteristics of collagen and fibroblasts in the soleus and gastrocnemius muscle tendon of female Japanese white rabbits with ageing. The fibroblasts decreased in number per 37 microns 2 with ageing in each group, and their morphology became longer and more slender through ageing. The mean fibril area and diameter of the collagen fibrils of soleus muscle tendon (SMT) and lateral gastrocnemius muscle tendon (GMT) in 8- to 10-month old rabbits were significantly higher than those of 3-wk-old rabbits during growth (P < 0.01). The mean area and diameter of collagen fibrils of SMT and GMT decreased during senescence: the values for 4- to 5-yr-old rabbits were lower than those for 8- to 10-month-old rabbits, but the difference was not significant. Statistically significant differences in fibril area and diameter between the SMT and GMT were not found during ageing. The number of thick fibrils increased during growth, but decreased in senescence. There were more thin fibrils (30-60 nm) in the 3-wk-old rabbits than in the 8- to 10-month old and 4 to 5-yr-old groups, and the large-diameter collagen (300-360 nm) was more abundant in the 8- to 10-month-old group than in the 3-wk-old and 4- to 5-yr-old groups. Differences in fibril size between slow and fast muscle tendons were not observed during ageing.

The purpose of this study was to determine whether the effect of arachidonic acid on hepatic O2 uptake is O2 dependent and which region of the liver lobule it affects. In livers perfused at normal flow rates, infusion of arachidonate increased O2 uptake significantly by about 20-25 mumol.g-1.h-1. When the flow rate was doubled to make the hepatic O2 gradient shallower, the increase in O2 uptake due to arachidonate was two to three times larger (i.e., approximately 50 mumol.g-1.h-1). In livers perfused in the retrograde direction, maximal rates of O2 uptake were about twofold higher in upstream pericentral than in downstream periportal regions, and arachidonic acid nearly doubled O2 uptake in downstream areas without affecting rates in upstream regions. Thus it is concluded that arachidonate stimulates O2 uptake in an O2-dependent manner. This effect was sensitive to an inhibitor of the lipoxygenase, nordihydroguaiaretic acid, in perfused liver but not in isolated hepatocytes. In addition, conditioned medium from Kupffer cells incubated at high O2 tension stimulated parenchymal cell O2 uptake. Furthermore, arachidonate increased intracellular Ca2+ in isolated Kupffer cells in a dose-dependent manner. These findings suggest that eicosanoids produced by nonparenchymal cells participate in a hepatic O2 sensor mechanism involving Ca2+ that regulates O2 uptake by parenchymal cells in the liver.

A 5,10,15,20-tetraphenylporphyrin (H2TPP; C44H30N4) film with an extra-flat surface was prepared on a Si(100) wafer substrate cooled down below 233 K. The organic molecular-beam deposition technique was used for fabrication of the film under ultra-high vacuum between 4 × 10−7 and 4 × 10−8 Pa. The r.m.s roughness determined by atomic-force microscope measurement was 0.22 nm, which is comparable to that of the Si substrate surface. Superlattice films of H2TPP/ZnTPP (5,10,15,20-tetraphenylporphyrinato zinc; C44H28N4Zn) were grown on Si and glass substrates in the same manner. Their periods between 12.1 and 2.37 nm were measured by small-angle X-ray scattering and confirmed by secondary-ion mass spectrometry depth profiling. The Fourier transform infrared spectroscopy measurement of the superlattice film with the minimum period of 2.37 nm indicated that the quasi-planar molecules of H2TPP and ZnTPP inclined at an angle of 75° with respect to the substrate surface. This suggests that an alternating molecular layer deposition of a single molecular layer was attained in the organic film for the first time.

We have established a new measurement method to evaluate the adsorbed moisture concentrations on solid surfaces exposed to the atmosphere having high moisture content ranging from 100 ppm to a few percent. The technique is based on the variation of the electric conductivity of anhydrous hydrogen fluoride. It has been found that the amount of adsorbed moisture on electropolished 316L stainless steel surface in an atmosphere with moisture concentration of 1% and 3% at 25 °C (relative humidity of 32% and 96% respectively) are 2.5× 1016 and 1.25×1017 molecules/cm2, respectively. This represents 25 and 125 molecule layers of water. The adsorbed moisture has been confirmed to reach an equilibrium level within an exposure time of 1 s.

Fibers of a cellulose-TiO(2) composite were prepared by the reaction of cellulose with titanium iso-propoxide. Enzymes were immobilized on the fibers easily and simply under mild conditions. The fibers were stable in common solvents, high ionic solutions, and over a wide range of pH values 3-10.

A superlattice film of 5, 10, 15, 20 tetraphenylporphyrin (H2TPP; C44H30N4) and 5, 10, 15, 20 tetraphenylporphyrinato zinc (ZnTPP; C44H28N4Zn) was grown on a hydrogen terminated surface of Si (100) wafer which was kept at −25 °C. The organic molecular beam deposition technique was used for the fabrication under ultrahigh vacuum between 3×10−9 and 3×10−10 Torr. The small angle x‐ray diffraction study has revealed that the period of the superlattice was 4.4 nm, which was also confirmed by the oscillation of the same period observed in a secondary ion mass spectrometry depth profile of Zn. The Fourier‐transform infrared spectroscopy measurement indicated that the quasi‐planar molecules of H2TPP and ZnTPP were inclined at an angle of 70° with respect to the substrate surface. The film surface was very flat and any roughness could not be detected by field emission secondary electron microscope observation. An atomic force microscope (AFM) therefore was used to investigate the surface. The root mean square roug...

The magnetic material Sm2Fe17Nx (0 < x < 6) can be prepared by reacting Sm2Fe17 in an NH3-H2 mixed gas atmosphere. As a fine powder, Sm2Fe17Nx (x = 3.0–3.2) exhibits the characteristics of single magnetic domain particles. The oxygen content of the particle increases to about 5 at.% with increasing specific surface area, but such an oxidized region is largely confined to an outer layer of the particle. The thickness of the O-rich layer is about 10 nm, as observed by transmission electron microscopy and Auger electron spectroscopy.

TiN films with a thickness of about 1.0 μm were formed on Si(111) using the dynamic ion beam mixing method at an acceleration voltage of 2–30 kV nitrogen ion current densities of 0.4–5 A/m 2 , and Ti evaporation rate of about 0.7 nm/s. The Vickers hardness of these films showed high values of 2300–3300 kg/mm 2 . Film characterizations were performed using the XRD, TEM, AEM and SIMS methods. An amorphous layer and a polycrystalline TiN layer were sequentially formed on Si substrates. Si, N and Ti atoms were detected in the amorphous layer. Ti in the amorphous layer was thought to be mainly knocked on by N + and N 2 + ions. At 2 and 5 keV nitrogen energy, the thickness of the amorphous layers was 5 and 12 nm, respectively, which corresponds closely with the projected range of N + ions. No clear boundary or void could be observed in the TiN layer.

Critical current densities Jc were measured in as‐deposited, c‐axis‐oriented Bi2Sr2Ca2Cu3Ox thin films with Tc values as high as 97 K, which were prepared by metalorganic chemical‐vapor deposition. These films showed high Jc (≳109 A/m2) at 77.3 K in high magnetic fields (≥1 T, H∥a‐b plane). The best values are 3.3×109 A/m2 at 1 T and 9.1×108 A/m2 at 8 T, which are the highest Jc for Bi‐oxide thin films among those reported so far. There were no signs of weak links in the Jc(H) behavior, and the surface morphology examined by scanning electron microscopy showed no apparent grain boundaries. The values of Jc decreased sharply when the applied field deviated from the a‐b plane, and went to zero at the angles where the field component in the c direction is nearly equal to the irreversibility field Hc2* parallel to the c axis. The angular dependence of Jc of these films is most reasonably explained by the theory of intrinsic pinning.

Effects of nitrogen content on crystal structure and magnetic properties have been investigated in Sm/sub 2/Fe/sub 17/N/sub x/. Sm/sub 2/Fe/sub 17/N/sub x/ specimens with 0 >

The optimum conditions for the fluorine passivation of 316L stainless steel are described. The direct fluoridation products formed at temperatures of 320 degrees C or lower are composed solely of FeF/sub 2/, while those which were formed at the temperatures of 330 degrees C or higher have a compound-phase composition of FeF/sub 2/ and FeF/sub 3/. At a critical temperature (400 degrees C for 316L stainless steel) of the thermal modification process, FeF/sub 3/ is converted to FeF/sub 2/ and disappears completely as the temperature rises. Meanwhile, CrF/sub 3/ is formed at a certain temperature (440 degrees C for 316L stainless steel). The two-phase composition gets further crystallized as the thermal modification temperature rises. As the crystal growth induces the cracks on the fluoridated film, it is very difficult to form a satisfactory passivation film from the two-phase composition by thermal modification. It is confirmed that excellent passivation film has been obtained from the single-phase composition by the optimum fluoridation following the optimum thermal modification. >

A compound Mn3InC possesses a cubic perovskite-type structure with lattice parameter 3.992 A. Mn3InC has a saturation moment at 4.2 K of 23.1 emu/g equivalent to 1.2 μB per molecule, the Curie temperature being ∼272 K. The paramagnetic susceptibility χ, measured over the temperature range 300–810 K, is found to vary with temperature in a manner different from normal ferromagnetic materials, the 1/χ-T curve possessing pronounced curvature concave to the temperature axis.