Electrochemical analysis of electrode-immobilized dehydrogenases in hydrated choline dihydrogen phosphate-type ionic liquid

A polar and hydrophilic ionic liquid, choline dihydrogen phosphate ([ch][dhp]), has been evaluated here as a medium for a bioelectrocatalytic process for generating cellulosic materials. The [ch][dhp] was mixed with water in proportions that best the competing requirements of solubilization and stabilization of enzymes, solution properties, and process conditions. Fructose dehydrogenase (FDH) and cellobiose dehydrogenase (CDH) were immobilized on gold or carbon nanoparticle-modified electrodes, and their biocatalytic oxidation was detected electrochemically in the hydrated [ch][dhp] (Hy[ch][dhp]). An improvement of the shelf life was found (>3 weeks) of CDH immobilized on the electrode in Hy[ch][dhp].     

Accelerated aromatic compounds degradation in aquatic environment by use of interaction between Spirodela polyrrhiza and bacteria in its rhizosphere

Accelerated degradation of organic chemicals by aquatic plant-bacterial associations was reported for the first time with elucidation of the role and contribution of aquatic plant and bacteria in its rhizosphere using a fast-growing giant duckweed, Spirodela polyrrhiza. The results clearly showed the accelerated degradation of all the three aromatic compounds (phenol, aniline and 2,4-dichlorophenol [2,4-DCP]) tested by aquatic plant-bacterial associations. In phenol degradation system, phenol-degrading bacteria indigenous to the rhizosphere fraction of S. polyrrhiza mainly contributed, while in aniline degradation system S. polyrrhiza mainly contributed by stimulating aniline-degrading bacteria both in the rhizosphere and balk water fraction. On the other hand in 2,4-DCP degradation system, S. polyrrhiza itself mainly contributed to its removal by uptake and degradation. Thus, the mechanisms for accelerated removal of aromatic compounds were quite different depending on the substrates. S. polyrrhiza showed selective accumulation of phenol-degrading bacteria in its rhizosphere fraction, while aniline- and 2,4-DCP-degrading bacteria were not much accumulated. S. polyrrhiza secreted peroxidase and laccase. However, both of the enzymatic activities increased with the addition of aromatic compounds, degrading ability of S. polyrrhiza itself should be owing to the production of peroxidase rather than laccase because the change of peroxidase activity and concentration of each aromatic compound well concurred. From the results obtained in the present study, it can be concluded that the feasibility of the use of aquatic plant-bacterial associations to accelerate the degradation of organic chemicals especially recalcitrant compounds in aquatic environment was shown.     

Influence of Oxidation Temperature and Cr Content on the Adhesion and Microstructure of Scale on Low Cr Steels

Descalability of steels during hot rolling processes is essential in order to maintain the surface quality of steel products, because the remaining scale can be impressed into the steel, producing surface defects. Therefore, a quantitative evaluation of scale adhesion at high temperature is needed in order to find suitable heating conditions for hot rolling processes that promote the formation of scale that easily detach. Round bar shape specimens of low Cr steels were oxidized in a fuel combustion environment, and then compressed at high temperature to detach the scale. The area fraction of the remaining scale was evaluated by image analysis. Under a thick outer oxide scale, a thin continuous inner oxide layer, which consisted of Cr and Si oxides, strongly adhered to the substrate, resulting in poor descalability. On the other hand, if this inner scale changed into a discontinuous layer with a porous FeO layer beneath, the descalability improved. It was found that scales with greater descalability formed on steels containing less Cr and for oxidation at higher temperatures.     

Nanostructural evolution in surveillance test specimens of a commercial nuclear reactor pressure vessel studied by three-dimensional atom probe and positron annihilation

The nanostructural evolution of irradiation-induced Cu-rich nanoprecipitates (CRNPs) and vacancy clusters in surveillance test specimens of in-service commercial nuclear reactor pressure vessel steel welds of Doel-1 and Doel-2 are revealed by combining the three-dimensional local electrode atom probe and positron annihilation techniques. In both medium (0.13 wt.%) and high (0.30 wt.%) Cu welds, the CRNPs are found to form readily at the very beginning of the reactor lifetime. Thereafter, during the subsequent 30 years of operation, the residual Cu concentration in the matrix shows a slight decrease while the CRNPs coarsen. On the other hand, small vacancy clusters of V₃–V₄ start appearing after the initial Cu precipitation and accumulate steadily with increasing neutron dose. The observed nanostructural evolution is shown to provide unique and fundamental information about the mechanisms of the irradiation-induced embrittlement of these specific materials.     

Study on failure modes of steel truss bridge gusset plates related to tension and shear block failure

Tension and shear block failure is a limit state which occurs in the connection of tension steel members. The failure mechanism is a combination of tensile failure on one plane and shear failure on the perpendicular plane. The design strength equations for the tension and shear block failure are described in the well known design codes. However, they provide inconsistent levels of safety when they are used in different types of connections. In this paper, the authors survey the design strength equations in the various codes. Then, the pertinent strength equations for the gusset plates of steel truss bridges are selected. Moreover, the authors propose a pair of strength equations for compression and shear block failure for gusset plates subjected to compressive force. And to examine the applicability of proposed equations and to investigate the mechanical behavior of compression gusset plates, parametric analyses on the various thicknesses of gusset plates were conducted.     

A firm as a knowledge-creating entity: a new perspective on the theory of the firm

The knowledge-based view of the firm views a firm as a knowledge-creatingentity, and argues that knowledge and the capability to createand utilize such knowledge are the most important source ofa firm's sustainable competitive advantage. Knowledge and skillsgive a firm a competitive advantage because it is through thisset of knowledge and skills that a firm is able to innovatenew products/processes/services, or improve existing ones moreefficiently and/or effectively. The raison d'être of afirm is to continuously create knowledge.     

Effect of Growth and Coalescence of Multisurface Cracks on Static Fatigue Behavior of Glass Ceramics

In order to study the effect of the interaction and coalescence of multisurface cracks on the static fatigue behavior of brittle materials such as glass and ceramics, a single crack and three collinear cracks were introduced on the surfaces of plate specimens of glass ceramics by Vickers microhardness indentation and were subjected to a constant four-point bending load. It was found that time-to-failure for a certain applied stress significantly decreased with the decrease in the crack center distance of indentation cracks, and the effect of interaction and coalescence of multicracks was shown to be significant. On the basis of the crack growth parameters for a single crack, time-to-failure for multicracks was predicted by taking the interaction and coalescence into consideration. It was demonstrated that the proposed multicrack coalescence model gives better predictions.