Bacterial communities in petroleum oil in stockpiles

Bacterial communities in crude-oil samples from Japanese oil stockpiles were investigated by 16S rRNA gene cloning, followed by denaturing gradient gel electrophoresis (DGGE) analysis. 16S rRNA genes were successfully amplified by PCR after isooctane treatment from three kinds of crude-oil sample collected at four oil stockpiles in Japan. DGGE profiles showed that bacteria related to Ochrobactrum anthropi, Burkholderia cepacia, Stenotrophomonas maltophilia, Propionibacterium acnes, and Brevundimonas diminuta were frequently detected in most crude-oil samples. The bacterial communities differed in the sampling time and layer. Among the predominant bacteria detected in the crude oil, only three species were found for bacteria isolated on agar plates and were related to Burkholderia, Stenotrophomonas, and Propionibacterium, while Ochrobactrum sp. could not be isolated although this species seemed to be the most abundant bacterium in crude oil from the DGGE profiles. Using an archaea-specific primer set, methanogens were found in crude-oil sludge but not in crude-oil samples, indicating that methanogens might be involved in sludge formation in oil stockpiles.     

Drying process in a solvent-based paint analyzed by phase-shifting digital holography and an estimation of time for tack free

A technique to study the drying of paints, based on phase-shifting digital holography, is presented. The technique is applied to the drying process of solvent-based paint on a three-dimensional surface at different substrate temperatures. For processing the data, a cross-correlation function and phase change derived from reconstructed complex amplitudes are calculated to visualize and to evaluate the local variations in the dryness of paint. The relationship between the optical signal obtained by the holographic method and the actual microscopic variations occurring in the paint film is also investigated using the gravimetric technique and a microscope. It is shown that the holographic technique can determine the stationary state of a painted surface corresponding to the end of the falling rate period in the drying process. The holographic technique detects mainly the activity on the surface and is applicable to assessment of the early drying process of paint.     

Thermoelectric Properties of the Narrow-Gap Intermetallic Compound Ga<Subscript>2</Subscript>Ru: Effect of Re Substitution for Ru Atoms

In this paper, the effect of hole doping on the thermoelectric properties of the binary narrow-gap semiconducting intermetallic compound Ga₂Ru in the temperature range from 373 K to 973 K was investigated. We synthesized sintered pellets by spark plasma sintering (SPS) after arc-melting and succeeded in preparing crack-free samples. The maximum dimensionless figure of merit ZT _max was 0.50 at 773 K for the sintered Ga₂Ru alloy. The temperature dependence of the electrical resistivity and its magnitude at 373 K dramatically changed from negative (~11,000 μΩcm) to positive (~200 μΩcm) upon hole doping by the substitution of Re for Ru atoms. Also, the Seebeck coefficient at 373 K changed from 300 μV/K to 75 μV/K. These changes were identified by the increase in carrier concentrations observed by Hall- effect measurements. In particular, large power factors (2.0 mW/m K² to 3.0 mW/m K²) were obtained over a wide temperature range from 373 K to 973 K upon Re substitution. The lattice thermal conductivity beneficially decreased with increasing Re concentration as a result of an alloying effect.     

A stretchable carbon nanotube strain sensor for human-motion detection

Devices made from stretchable electronic materials could be incorporated into clothing or attached directly to the body. Such materials have typically been prepared by engineering conventional rigid materials such as silicon, rather than by developing new materials. Here, we report a class of wearable and stretchable devices fabricated from thin films of aligned single-walled carbon nanotubes. When stretched, the nanotube films fracture into gaps and islands, and bundles bridging the gaps. This mechanism allows the films to act as strain sensors capable of measuring strains up to 280% (50 times more than conventional metal strain gauges), with high durability, fast response and low creep. We assembled the carbon-nanotube sensors on stockings, bandages and gloves to fabricate devices that can detect different types of human motion, including movement, typing, breathing and speech.     

Interspecies comparison of hepatic metabolism of six newly synthesized retinoid X receptor agonistic compounds possessing a 6-[N-ethyl-N-(alkoxyisopropylphenyl)amino]nicotinic acid skeleton in rat and human liver microsomes

Objective: The hepatic metabolism of six compounds newly synthesized as retinoid X receptor agonists was characterized in rat and human liver microsomes to examine the relationship between their hepatic metabolism profiles and side chain structures, considering the interspecies difference.

Materials and methods: The compounds used have a 6-[N-ethyl-N-(3-alkoxy-4-isopropylphenyl)amino]nicotinic or 6-[N-ethyl-N-(4-alkoxy-3-isopropylphenyl)amino]nicotinic acid skeleton, in which the isopropoxy, isobutoxy or cyclopropylmethoxy group is employed for the alkoxy group. These compounds were incubated with the microsomes, and their Michaelis--Menten parameters were determined. The incubation study was also performed with various cytochrome P450 (CYP) inhibitors to examine their susceptibilities to the inhibitors. In addition, a molecular docking simulation was conducted to assess the compound’s spatial configuration with the CYP isoform when necessary.

Results: The Michaelis--Menten parameters determined are comparable between rats and humans for the compounds having 3-isobutoxy, 4-isobutoxy, 4-isopropoxy and 4-cyclopropylmethoxy groups. However, it was indicated that all compounds except that having the 3-isobutoxy group are metabolized in a different manner between rats and humans. That is, the extent of the contribution of each CYP isozyme is different between those two species. A molecular docking simulation showed that the spatial configuration of the compound to be associated with CYP2D6 markedly changes depending on whether the isobutoxy group is situated at the 3- or 4-position.

Conclusion: A slight difference in the side chain structures markedly alters the compound’s metabolic profile, which amplifies the interspecies difference regarding the profile, increasing the difficulty in characterizing the profile in humans with the structural-property relationship and interspecies extrapolation.     

Fatigue behaviour of dissimilar friction stir welds between wrought and cast aluminium alloys

Wrought aluminium alloy, A6016-T4, was welded to cast one ADC12 by a friction stir welding technique. A6016 was set on the advancing side, while ADC12 was on the retreating side based on the pre-tensile test results. The dissimilar welds exhibited lower fatigue strengths than A6016 but higher than that of ADC12. Fatigue strengths increased when the tool was offset into ADC12, which could be explained based on the risk volume concept. When ADC12 was set on the advancing side, the fatigue strengths decreased. Microstructural observation revealed that the macroscopic structure in the stir zone drastically changed by putting ADC12 on the advancing side, and insufficient mixing of dissimilar alloys resulted in the lower fatigue strengths.