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.     

Modeling technological learning and its application for clean coal technologies in Japan

Estimating technological progress of emerging technologies such as renewables and clean coal technologies becomes important for designing low carbon energy systems in future and drawing effective energy policies. Learning curve is an analytical approach for describing the decline rate of cost and production caused by technological progress as well as learning. In the study, a bottom-up energy-economic model including an endogenous technological learning function has been designed. The model deals with technological learning in energy conversion technologies and its spillover effect. It is applied as a feasibility study of clean coal technologies such as IGCC (Integrated Coal Gasification Combined Cycle) and IGFC (Integrated Coal Gasification Fuel Cell System) in Japan. As the results of analysis, it is found that technological progress by learning has a positive impact on the penetration of clean coal technologies in the electricity market, and the learning model has a potential for assessing upcoming technologies in future.     

Synthesis of iron nanoparticle: Challenge to determine the limit of hydrogen reduction in supercritical water

Supercritical hydrothermal syntheses of metal nanoparticles were investigated. Organic metal salt and hydrogen gas produced by water catalyzed decomposition of formic acid was employed as metal sources and reduction agent, respectively. The formation of iron was verified by measuring the magnetic property of the products by superconducting quantum interference device (SQUID) magnetometer as well as crystallographic analysis by X-ray diffraction (XRD). As predicted by the free energy calculation of reduction of metal oxides by hydrogen molecule, silver, palladium, copper, nickel and cobalt nanoparticles were synthesized without using surface modifier, whereas, iron could be synthesized at small yield. The main product was iron oxides (mainly magnetite). In order to increase the yield of iron, hexanoic acid was employed as an in situ surface modifier of the synthesis. The surface modification lessened the size of the synthesized nanoparticles and increased the yield of iron. The optimum condition for iron synthesis was also investigated, as a result, 7.6% yield of iron was achieved.     

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.     

PID landing orbit motion controller for an indoor blimp robot

Blimp robots are attractive as indoor flying robots because they can float in the air, land safely with low energy, and stay in motion for a long time compared with other flying robots. However, controlling blimp robots is difficult because they have nonlinear characteristics, are influenced by air streams, and can easily be influenced by inertia. Therefore, a robust and adaptive control system is needed for blimp robots. The applied research that has studied the features of indoor flying robots in recent years has prospered. Operating an indoor blimp robot for a long time is difficult because the payload is small, multiple batteries cannot be stacked, and the design of a thruster that gives freedom to the entire blimp robot is difficult. Therefore, an autonomous charge that allows operation for a long time is needed. We have developed a method of landing with orbital control of the charge point that gives autonomy to a blimp robot. The possibility of landing with orbital control is shown. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005 An erratum to this article is available at .     

Localization of mRNA for inflammatory cytokines in radicular cyst tissue by in situ hybridization, and induction of inflammatory cytokines by human gingival fibroblasts in response to radicular cyst contents

The expression of mRNA encoding the inflammatory cytokines interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor alpha(TNF-alpha) have been examined in radicular cysts by in situ hybridization. Furthermore, the biological activity of the contents of radicular cysts (RCC) has been assayed by adding extracts of RCC to cultured human gingival fibroblasts (HGFs) and analyzing the culture medium for the release of inflammatory cytokines. In the epithelial layer, keratinocytes expressed all cytokine mRNAs examined at various levels. Basal layer cells expressed mRNA for each cytokine. In the subepithelial granulation tissue of the cysts, fibroblasts and macrophages expressed mRNA for IL-6, IL-8, IL-1beta and TNF-alpha mRNA at varying levels; especially clear expression of TNF-alpha and IL-1beta mRNA was detected on macrophages. The infiltrating lymphoid cells, largely composed of T cells and plasma cells, expressed these cytokine mRNAs, especially those encoding IL-6 and IL-8, at various levels. In vitro analysis indicated dose-dependent release of both IL-6 and IL-8 by HGFs in response to RCC. After heating to 100 degrees C for 10 min, RCC almost completely failed to stimulate IL-6 release from HGFs. Furthermore, anti-IL-1beta antibody (neutralization test) did not prevent the stimulation of IL-6 release by RCC. Significant amounts of IL-6 and IL-8 were detected in RCC in two cases, and a trace amount of IL-1beta was detected in one case. This study demonstrated the wide expression of mRNA encoding inflammatory cytokines in radicular cyst tissues, and RCC itself was capable of stimulating IL-6 and IL-8 production from HGFs.