Hydrogen production by combining two types of photosynthetic bacteria with different characteristics

The double-layer photobioreactor using two types of photosynthetic bacteria, Rhodobacter sphaeroides RV and its reduced-pigment mutant, MTP4, was developed for efficient hydrogen production. The two types of bacteria had different characteristics on light energy, hydrogen production rate and conversion efficiency. MTP4 produced hydrogen more efficiently under high light conditions and RV did so under low light conditions. Illuminated light toward the surface of a photobioreactor quasi-exponentially declines as it penetrates into the reactor. When two types of bacteria were placed using the developed reactor according to this light distribution, the hydrogen production rate reached 3.64 l/m²/h at a light intensity of 500 W/m² in 24 h and the conversion efficiency of light energy to hydrogen was 2.18%. These values were 33% higher than those of only using RV. The low light in the deep part of the reactor was utilized efficiently, resulting in a higher hydrogen production rate.     

Effect of anisotropic yield functions on the accuracy of hole expansion simulations

The deformation behavior of 780 MPa grade dual-phase steel sheet subjected to hole expansion is investigated both experimentally and analytically to clarify the effect of the material model (anisotropic yield function) on the predictive accuracy of finite element analysis of hole expansion. Biaxial tensile tests of the material were conducted; contours of plastic work and the directions of plastic strain rates are precisely measured and are in good agreement with those predicted from the Yld2000-2d yield function with an exponent of 4 ( [Barlat et al., 2003] and [Yoon et al., 2004]). Finite element and experimental analyses on the hole expansion of the material were conducted. The Yld2000-2d yield function with an exponent of 4 provides closer agreement with the experimental results than other yield functions. Consequently, the anisotropic yield functions significantly affect the predictive accuracy of the deformation behavior of the steel sheet subjected to hole expansion, and the biaxial tensile test is effective for identification of the appropriate anisotropic yield function to be used for hole expansion simulation.     

Performance of a solid oxide fuel cell couple operated via in situ catalytic partial oxidation of n-butane

The operation of a pair of anode-to-anode-facing solid oxide fuel cells (SOFCs) via in situ catalytic partial oxidation (CPO) of n-butane was investigated. In this simple “no-chamber” setup, butane is partially oxidized by heterogeneous reactions inside the porous anodes, providing processed fuel and the heat required for SOFC operation. The cell couple yielded a power density of up to 270 mW cm⁻², and the maximum total power obtained was 1.2 W with cell sizes of 13 mm × 23 mm. The maximum electrical efficiency was 1.3%. High CO concentrations of up to 1000 ppm were detected in the exhaust gas, indicating that the cell couple could not efficiently consume the complete provided fuel. A flame, lit at the exhaust, minimized the carbon monoxide level while having insignificant influence on the cell performance. Thermal insulation of the cell couple improved the output remarkably, showing the strong influence of temperature on cell performance. The two cells had a distance of only 2 mm, suggesting a potential for high volumetric power densities in multi-cell configurations for a self-sustained combined heat and power system.     

Room-Temperature Sintering Process of Ag Nanoparticle Paste

Recently, the authors developed a novel room-temperature wiring method using Ag nanoparticle paste. In this paper, the sintering mechanism of the Ag nanoparticle paste was clarified through examination of the adsorption stability and the removal of the dispersant from the Ag nanoparticles. The Ag nanoparticles in the paste are protected by dodecylamine as a dispersant. This paste possesses substantially long shelf life and thermo stability at room temperature. When the printed line of the Ag nanoparticle paste is dipped in a methanol bath, methanol effectively dissolves and removes the dispersant from the nanoparticles. Ag nanoparticles are sintered within a short period. The sintering of Ag nanoparticles is not uniform. Some Ag nanoparticles quickly grow and form a network by sintering (necking). The others maintain a nanometer scale. Large Ag particles and an Ag skeleton continue to grow by absorbing very small nanoparticles. In addition, the use of ethanol and isopropanol as the treatment agent is shown for the first time.     

Calcitonin gene-related peptide (CGRP)-containing nerve fibers in bone tissue and their involvement in bone remodeling

Bone remodeling is a process of bone renewal accomplished by osteoclastic bone resorption and osteoblastic bone formation. These two activities are regulated by systemic hormones and by local cytokines and growth factors. Moreover, the nervous system and certain neuropeptides seem to be involved in regulation of bone remodeling. In this paper, we focus on the distribution of CGRP-containing nerve fibers and their dynamics, and discuss the role of these fibers as a possible mechanism for nervous system involvement in regulation of bone remodeling. CGRP-immunoreactive nerve fibers are widely distributed in bone tissue, such as periosteum and bone marrow, and show apparent regional distribution with different densities. They are often associated with blood vessels and show a beaded appearance. The wide distribution of CGRP-immunoreactive nerve fibers in bone tissue and the changes in distribution during bone development and regeneration suggest the involvement of these fibers in bone remodeling. The effect of CGRP on bone remodeling could partly be through its action on blood vessels, thereby regulating local blood flow. Moreover, in vitro biochemical data and the localization of CGRP-immunoreactive nerve fibers in the vicinity of bone cells suggest that they are directly involved in local regulation of bone remodeling by elevating the concentration of CGRP in the microenvironment around bone cells, especially during bone growth or repair.     

Deletion and insertion of a 192-residue peptide in the active-site domain of glycosyl hydrolase family-2 beta-galactosidases

The monomeric multimetal-binding beta-galactosidase of Saccharopolyspora rectivirgula (srbg), a glycosyl hydrolase family-2 enzyme, has a unique sequence consisting of 192 amino acid residues with no similarity to known proteins. This 192-residue sequence (termed the "iota [iota] sequence") appears to be inserted into a sequence homologous to the active-site domain of the Escherichia coli lacZ enzyme (lacZbg). To assess the effects of the t sequence at specific sites of beta-galactosidase on the catalytic functioning and molecular properties of beta-galactosidase, deletion or insertion mutants of beta-galactosidases were constructed, expressed in LacZ- E. coli strains, and characterized: srbgdelta in which the iota sequence was deleted from srbg, and lacZbgI, in which the 192-residue iota sequence was inserted into the corresponding position (between Asp591 and Phe592) in the active-site domain of lacZbg. srbgdelta was a catalytically inactive, dimeric protein which retained multimetal-binding characteristics, suggesting that the iota sequence is very important for maintaining the structure necessary for the catalytic functioning and the monomeric structure of srbg but is not responsible for the unique metal ion requirements of srbg. On the other hand, lacZbgI existed as a mixture of a monomer, a tetramer, and higher multimers. The monomeric species was inactive, whereas the tetramer and other multimers were catalytically active (V(max )K(m) value, 25% of that of lacZbg) and highly specific for beta-D-galactoside. The tetrameric lacZbgI was activated by Mg2+ and Mn2+ with lowered metal affinities, and the stoichiometry of metal binding was unchanged from that of lacZbg. These results, along with the published stereo structure of lacZbg, suggest that, in lacZbgI, the inserted 192-residue iota peptide could fold independently of the lacZbg domains into a "sub-domain," lying distant from the active site and subunit interfaces.     

Fracture properties of X-phase precipitation hardened ferritic stainless steel and ductility improvement of the steel

The mechanical properties of Fe-13 wt% Cr-2 wt% Mo-2.5 wt% Ti alloy were examined by tensile tests with respect to its fracture mechanism. In order to improve the properties, 1 wt% Nb was added and its effects were examined. In the temperature range, room temperature to 500° C, the fracture characteristics of the alloys are mainly governed by the characteristics of the x-phase precipitation. Fracture elongation is a function of (C/r)_1/2 where C is the radius of the x-phase and r is its mean spacing. 1 wt% Nb addition is an effective method for improving the ductility without a decrease in the strength of the alloy.     

Characterization of infrared and near-infrared absorptions of free alcoholic OH groups in hydrocarbon

We have demonstrated that the near-infrared and infrared absorptions in the 8000-3200 cm(-1) region of an OH group of 2-nonanol, 1-nonanol, etc., in n-heptane are excellently separated by subtraction without any serious interference down to very low concentrations at which OH groups are completely free. The separated sharp absorptions are assigned to the fundamental, combination, and overtone bands that are concerned with the OH stretching of free OH. Two components of a sharp overtone band around 7100 cm(-1), which are observed for primary and secondary alcohols, are assigned to coexisting internal rotational isomers of an OH group around the O-C bond. The frequencies of the OH stretching fundamental and overtone bands that are assigned to internal rotational positions are consistent for all the investigated alcohols, including methanol and tertiary butanol. Comparison of the separated spectrum of 2-nonanol in n-heptane with that in 1-chlorooctane or in carbon tetrachloride makes it clear that hydrocarbon is an inert solvent that does not disturb the intrinsic nature of an alcohol OH group. There actually exists a constant anharmonicity shift of 169-175 cm(-1) between the double frequency (2nu(OH)o) of the observed fundamental and the observed overtone frequency ([2nu(OH)]o) for free OH of various alcohols in n-heptane.