Expression of aldehyde dehydrogenase gene increases hydrogen production from low concentration of acetate by Rhodobacter sphaeroides

Rhodobacter sphaeroides RV (RV) is a hydrogen-producing bacterium exhibiting the highest yield of hydrogen production from organic acids such as lactate and acetate, which are the byproducts of hydrogen fermentation by hydrogen-producing anaerobic bacteria. Co-fermentation of the RV strain with anaerobic bacteria is an efficient method of hydrogen production. However, less than 21 mM acetate is produced by the anaerobic bacteria, which is too low for efficient hydrogen production by the RV strain; it requires approximately 75 mM acetate. In this study, 2 distinct isozymes of aldehyde dehydrogenase from Rhodospirillum rubrum were separately overexpressed in the RV strain. The recombinant RV strains that were designated as RVAD1 and RVAD2, exhibited 13-fold higher ALDH activities than the wild-type RV strain. Hydrogen yields of both of the recombinant strains were 1.4-fold higher than that of the RV strain in 21 mM acetate. In 43 mM acetate, the RVAD1 strain showed higher yield, though the RVAD2 strain showed lower yield as compared to that of the RV strain. In 64 mM acetate and all concentrations of lactate tested (21, 43 and 64 mM), the yields of the recombinant strains were lower than those of the RV strain. The intact (empty) expression plasmid increased the ALDH activity and had little effect on the hydrogen production in acetate, however, it decreased the production in lactate. At the beginning of the fermentation process, when very little hydrogen had been produced, the recombinant strains expressing the ALDH gene consumed smaller amounts of acetate compared to the wild-type strain. We have discussed the effects of ALDH on hydrogen production in this report.     

Colloidal platinum in hydrogen-rich water exhibits radical-scavenging activity and improves blood fluidity

The 'colloidal platinum' stabilized with polyvinylpyrrolidone (Pt/PVP-colloid) was dispersed in hydrogen-rich water (HW; hydrogen concentration, 0.82 ppm; oxidation-reduction potential, -583 mV) or regular water (RW; <0.01 ppm, +218 mV). And we evaluated the antioxidant activity of Pt/PVP-colloid in HW or RW on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and improvement of blood fluidity under 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced oxidative stress. When applied with the 0.25-0.5 ppm Pt/PVP-colloid in RW or HW, the level of DPPH radicals decreased to 77.5-59.6% or 16.1-5.6%, in contrast to the level as high as 81.3% for HW alone, respectively, as measured by an electron spin resonance method. The horse blood, which was subjected to AAPH-induced oxidative stress, was incubated for 24 hr with RW or HW, and thereafter required 13.7 sec (100%) or 5.7 sec (42.3%) for passing through the micro-channels in a rheology equipment. When treated with 0.5-1.0 ppm Pt/PVP-colloid in RW or HW, the blood passage time in the micro-channels decreased dose-dependently to 9.7-7.3 sec (71.6-53.8%) or 4.3-1.3 sec (32.8-10.3%), and the rate of micro-channels clogged with erythrocyte aggregates decreased to 23.8-21.0% or 15.8-9.8%, respectively, from 42.8% for no addition of Pt/PVP. By scanning electron microscopy, AAPH-treated erythrocytes lost intact surface morphology on the membrane together with protrusions and without hollows, being indicative of impaired transforming ability, and the rate of erythrocyte agglutination was increased to 46.2%. When treated the horse blood with HW alone significantly decreased the rate of erythrocyte agglutination to 29.6%, whereas 1.0 ppm Pt/PVP-colloid in RW or HW decreased it to 24.1% or 21.1%, respectively. Thus, DPPH-radical-scavenging and erythrocyte-protecting effects of Pt/PVP-colloid in HW were superior to those of Pt/PVP-colloid in RW or Pt/PVP-free HW. The results could be mainly attributed to the enhanced antioxidant activity of Pt/PVP in HW, which may be due to captured-hydrogen on platinum.     

Enhanced radiosensitization by liposome-encapsulated pimonidazole for anticancer effects on human melanoma cells

The nitroimidazole-related hypoxic radiosensitizer, pimonidazole (Pmz) was encapsulated in liposome composed of dipalmitoylphosphatidylcholine, cholesterol and dipalmitoylphosphatidylglycerol (molar ratio = 1:1:0.2; diameter = 112.9 nm), and the radiosensitization was evaluated in human melanoma cells HMV-II. Cell proliferation was examined by WST-8 assay after X-ray irradiation in the presence of liposomal Pmz or free-Pmz under hypoxic conditions. On 7th day after X-ray irradiation of 5 Gy, cell proliferation decreased more markedly in the administration of liposomal Pmz than free-Pmz at equivalent Pmz doses. Chromatin fragmentation or nuclear condensation was observed in liposomal Pmz-treated HMV-II cells. Radiosensitization was enhanced dose-dependently along with Pmz amounts of 250-2000 microM contained in liposomal Pmz. Intracellular uptake was more abundant for liposomal Pmz for 60-240 min than for free-Pmz. Thus liposomal Pmz has a potential to overcome radiation resistance in hypoxia, owing to enhanced intracellular uptake by melanoma cells.     

Carbon composite microelectrodes fabricated by electrophoretic deposition

Single-walled carbon nanotubes were deposited on one end of the etched carbon fiber electrodes by an electrophoretic method. The carbon nanotube bundles formed a dense network on the carbon fiber surface. The electrochemical properties of the composite carbon electrodes were studied in the buffered neutral solutions. The results in cyclic voltammetry's characteristic indicate that the electrons on the electrodes transfer very fast. Furthermore, the redox reactions of dopamine (DA) on the composite electrodes show good sensitivity. When the DA concentration was 0.02 mM, the peak current in differential pulse technique reached 1.33 microA after performing the background subtraction. In addition, the simultaneous detection of DA and ascorbic acid (AA) showed that the interference effect was not observed. It was suggested that the carbon composite microelectrodes have potential applications as electrochemical sensors inside a single cell.     

10 micrometer-scale SPM local oxidation lithography

10 micrometer-scale scanning probe microscopy (SPM) local oxidation lithography was performed on Si. In order to realize large-scale oxidation, an SPM tip with a contact length of 15 microm was prepared by focused-ion-beam (FIB) etching. The oxidation was carried out in contact mode operation with the contact force ranging from 0.1 to 2.1 microN. The applied bias voltage was 50 V, and scanning speed was varied from 10 to 200 microm/s. The scan length was 15 microm for one cycle. The influence of contact force on the large-scale oxidation was investigated. At high contact force, the Si oxide with good size uniformity was obtained even with high scanning speed. The SPM tip with larger contact length may increase the spatial dimensions of the water meniscus between the SPM tip and sample surface, resulting in the larger dimensions of the fabricated oxide. Furthermore, the throughput of large-scale oxidation reached about 10(3) microm2/s by controlling the scanning speed and contact force of the SPM tip. It is suggested that SPM local oxidation can be upscaled by using a SPM tip with large contact length.     

Fracture strength distribution of porous ceramics under quasi-static load

The purpose of this paper is to estimate the fracture strength distribution of porous ceramics under quasi-static load. Four-point bending test was performed for SiC-porous ceramics at room temperature under quasi-static load. Fracture strength distributions obtained in the above test were estimated with the aid of a conventional probabilistic time-dependent fracture model on the basis of the slow crack growth concept in conjunction with two-parameter Weibull distribution. The results showed that the estimated fracture strength distribution curves were not in good agreement with the experimental data at stress rates. Porous ceramics have damage-tolerable property due to failure of a lot of grain boundaries. Therefore, this is because the dispersion of applied stress was not considered in the conventional model. A new probabilistic time-dependent fracture model considered the dispersion of applied stress was proposed based on Markov process in conjunction with local load sharing rule. The fracture strength distribution curves estimated the aid of the new model were in reasonably good agreement.     

Tribological Properties of Patterned NiFe-Covered Si Surfaces

The tribological properties of patterned surfaces were investigated under lubricated conditions. Micropatterns were fabricated on a Si surface using a combination of photolithography and plasma etching. NiFe film with a 150 nm thickness was then deposited on the patterned Si surface. We prepared four kinds of patterned surfaces: dimple, grating, bump, and mesh patterns. The dimensions of the patterns were: size 30–40 μm, pitch 120 μm, and depth 10–12 μm. Friction tests were carried out using a pin-on-plate tribometer. The pin specimen was made of cast iron and had a flat end. The normal load was varied from 9.8 to 98 mN, and the average sliding speed from 1.0 to 5.0 mm s⁻¹. Slideway lubricating oils or a gear oil were used as the lubricant, and the ISO viscosity grades of these oils were VG32, VG68, and VG320. The results showed that the friction coefficients of the two reverse patterns showed very similar tendencies and that circular patterns had a lower friction coefficient than did the rectangular patterns at a high bearing characteristic number. The surface geometry of the Si surface did not affect the friction coefficients at a low bearing characteristic number.     

An optimization approach to establish an appropriate energy group structure for BWR pin-by-pin core analysis

An optimization approach to establish an appropriate multi-group energy structure for boiling water reactor (BWR) pin-by-pin fine mesh core analysis is proposed. In the present approach, the number of energy groups of cross sections is successively reduced or increased. In order to select an energy group boundary that is removed or added, performances of all possible candidates of energy group structures are tested in multi-assembly geometries. Then, the energy group boundary, which provides the minimum difference of the k-infinity or the pin-by-pin fission rate distribution, is finally removed or added. This procedure is repeated until the number of energy groups reaches to the target value. In order to confirm the applicability of the present approach, the accuracies of the k-infinity and the pin-by-pin fission rate distribution are investigated in various 2 × 2 multi-assembly geometries with the established energy group structure. From the verification results, the differences of the k-infinity and the pin-by-pin fission rate distribution between the reference (fine) and the established (coarse) energy group structure are small in the various 2 × 2 multi-assembly geometries. Therefore, we can conclude that the present approach is efficient to establish an appropriate energy group structure for BWR pin-by-pin fine mesh core analysis.     

Allene as an alternative functional group for drug design: effect of C--C multiple bonds conjugated with quinazolines on the inhibition of EGFR tyrosine kinase

A series of allenic quinazolines were synthesized as receptor tyrosine kinase inhibitors by using a simple protocol for palladium-catalyzed allene transformation. Among the compounds synthesized, two allenic 4-anilinoquinazolines selectively suppressed epidermal growth factor receptor (EGFR) tyrosine kinase activity in vitro. According to immunoblot analysis, the allenic quinazolines inhibited the EGF-mediated phosphorylation of EGFR and its downstream kinases in A431 cells. Furthermore, one of these allenic quinazolines decreased the proliferation of A431 cells through the induction of cell-cycle arrest and apoptosis.     

Temperature dependences of piezoelectric properties of vanadium substituted SrBi2Nb2O9 ceramics with grain orientation

The temperature dependence of the piezoelectric properties of vanadium substituted strontium bismuth niobate, SrBi₂Nb_1.95V_0.05O₉ (SBNV) ceramics, were investigated in various vibration modes. The effects of grain orientation in SBNV ceramics on the piezoelectric properties were also studied by the hot-forging (HF) method. The anisotropy of the piezoelectric properties of each vibration mode was confirmed by observing the grain orientation. In particular, HF-SBNV ceramics of the (33) and (15) modes showed excellent piezoelectric properties with relatively high mechanical quality factors, Q_m (2200, 4600), and high electrical quality factors, Q_{e max} (66.0, 21.6), respectively. In addition, HF-SBNV ceramics showed low temperature coefficients of resonance frequency TC-f_r (−16.5, −27.0). HF-SBNV ceramics are considered to be superior candidates for the lead-free piezoelectric application of ceramic resonators.