Darío E. IGLESIAS^*, Silvina S. BOMBICINO, Alberto BOVERIS, Laura B. VALDEZ

BIOCELL, Vol.40, No.1, pp. 27-30, 2016, DOI:10.32604/biocell.2016.40.027

Abstract Complex III plays a central role in the mitochondrial respiratory chain transferring electrons from ubiquinol to cytochrome c and pumping protons to the intermembrane space, contributing to the protonmotive force. Furthermore, complex III can act as a source of O₂ •- in the presence of ubiquinol and antimycin, an expermiental condition in which the oxidation of the cytochrome b hemes is blocked. The O₂ •- dismutation catalyzed by superoxide dismutase produces H₂O₂, a known second messenger in redox signalling. Results from our laboratory have shown that NO, released from GSNO or from SPER -NO or generated by mtNOS, inhibits electron… More >

San-Qiang Shi

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.2, pp. 35-36, 2011, DOI:10.3970/icces.2011.020.035

Abstract Zirconium and its alloys are key structural materials used in the nuclear power industry. In service, these metals are susceptible to a slow corrosion process that leads to a gradual pickup of hydrogen impurities from the environment. It is well known that hydrogen impurity will be attracted to stress concentrators such as notch and crack tips. At a certain hydrogen level, a complicated pattern of hydride precipitates can develop around these stress concentrators. Because of the brittleness of these hydrides, the original strength of the alloys can be reduced by orders of magnitude, and the fracture through these hydrides may… More >

Ralph H. Scheicher

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.3, pp. 93-94, 2011, DOI:10.3970/icces.2011.019.093

Abstract The purpose of this talk is to provide an overview of the most recent theoretical studies undertaken by us in the field of hydrogen storage materials research. On selected examples, the application of our computational tool of choice, density functional theory, will be illustrated to show how ab initio calculations can be of use in the effort to reach a better understanding of hydrogen storage materials and to occasionally also guide the search for new promising approaches. Systems to be discussed include: Metal-organic frameworks, where we have studied hydrogen physisorption in three different types of iso-reticular MOFs, namely Zn-/Mg-/Ca-MOF16, decorated… More >

A. Takayama, S. Saito, A. M. Ito, S. Yonemura, H. Nakamura

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.3, pp. 83-84, 2011, DOI:10.3970/icces.2011.019.083

Abstract We have been developing a molecular dynamics (MD) simulation code, a binary collision approximation (BCA) based simulation code, and a BCA-MD hybrid simulation code. In this paper, an overview of the codes is presented. BCA-based simulation results of hydrogen isotopes injection into graphite target are also shown. Detailed description is given as a full abstract. More >

Gotthard Seifert, Aliezer Martinez Mesa, Sergei Yurchenko, Bassem Assfour¹, Thomas Heine³, Sergei Patchkovsk

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.1, pp. 21-22, 2011, DOI:10.3970/icces.2011.018.021

Abstract In this study structural characteristics of several carbon based nanostructures and organic frameworks as metal organic frameworks (MOF) and covalent organic frameworks (COF) on the hydrogen abundance in the material are investigated with the quantized liquid density functional theory (QLDFT), Molecular Dynamics (MD) and Grand Canonical Monte Carlo (GCMC). We applied these theories to evaluate the hydrogen storage capacities of nanoporous materials: Compact storage of hydrogen is the key challenge facing adoption of hydrogen as fuel for mobile applications. A promising approach to increase the storage densities is the adsorption of molecular hydrogen in porous environments. We have studied in… More >

Nobuyuki Ishikawa^1,*, Yuya Sato¹, A. Toshimitsu Yokobori Jr.², Tadashi Kasuya³, Satoshi Minamoto⁴, Takehiro Endo³, Manabu Enoki³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 138-138, 2019, DOI:10.32604/icces.2019.05518

Abstract Prediction model for weld hydrogen cracking (so called cold cracking) in high strength steel weld was developed by a coupled thermo-elastic-plastic and hydrogen diffusion analysis in the y-grooved weld joint. Critical conditions of cracking was given as the function of principal stress and accumulated hydrogen concentration in the root region where the cracking occurs. In order to clarify the critical conditions of cold cracking, y-grooved cold cracking tests were first conducted using the steel plate with tensile strength level of 780MPa. Plate thickness of the plates were 25 mm and 50 mm. Hydrogen concentration in the weld metal was changed… More >

J. Toribio¹, V. Kharin²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.3, pp. 135-140, 2008, DOI:10.3970/icces.2008.007.135

Abstract This paper deals with the meaning and significance of the fracture mechanics approach to hydrogen assisted cracking, analyzing the question of K-dominance not only over the purely mechanical aspects, but also over the environmental (physicochemical) events. Two key factors able to violate the uniqueness of the crack growth kinetics curve v = v(K) are discussed: the role of far field (the stress-strain field which is not K-dominated) and the effect of the history of hydrogenation and crack growth. The far field is shown to have a minor effect on near-tip hydrogen diffusion, and thus it can only widen the scatter… More >

M. Katagiri, H. Onodera¹, H. Ogawa², N. Nishikawa³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.6, No.1, pp. 72-80, 2008, DOI:10.3970/icces.2008.006.072

Abstract The microscopic mechanism of Hydrogen-Induced Amorphization (HIA) in C15 Laves phases of AB$_2$ compounds is studied. Experimentally, compounds in which the AA internuclear distance is reduced and BB internuclear distance expanded compared to pure crystals show Hydrogen-Induced Amorphization which suggests that the relative atomic size is the controlling factor. We investigate the role of the size effect by static and Molecular Dynamics methods using Lennard-Jones potentials. Our simulations show that in such a compound, the bulk modulus is remarkably reduced by hydrogenation compared to the isotropic tensile load, so that elastic instability is facilitated. This situation is caused by the… More >

Tadashi Kasuya^1,*, A. Toshimitsu Yokobori Jr², Nobuyuki Ishikawa³, Manabu Enoki¹, Satoshi Minamoto⁴

The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 120-120, 2019, DOI:10.32604/icces.2019.05227

Abstract Weld cold cracking is categorized as hydrogen cracking. To assess cold cracking susceptibility of steel HAZ (heat affected zone), it is necessary to estimate local hydrogen content and residual stress at a weld root that are in general numerically calculated by FEM and/or FDM. To conduct numerical calculations, physical and mechanical properties such as diffusion coefficient of hydrogen in steel are necessary. In this work, we have developed empirical formulae to calculate HAZ hardness, hydrogen diffusion coefficient and tensile properties. The present empirical formula of HAZ hardness is expressed using chemical compositions of a welded steel and weld thermal history.… More >