An approach for ergonomic design of mouse wheel

A new method for ergonomic design of a computer mouse is proposed in this paper.In the method,the movements of joints and tip of the forefinger during operating a mouse was captured by a high-speed video camera.The captured videos were analyzed and an algorithm was developed to decide the size and location of the mouse wheel according to ergonomic principles.The algorithm was then coded in a software package with Visual C++ and OpenGL languages.Results of the calculation and simulation agreed well with those of the experiments.The software can also be used for shape design of mouse body,buttons and their layouts.     

Study of cysteine residues in the {alpha} subunit of Escherichia coli tryptophan synthase. 1. Role in conformational stability

To eludicate the role in conformational stability of Cys residuesburied in the interior of a protein, the thermodynamic propertiesof denaturation of mutant subunit of Escherichia coli tryptophansynthase, in which Ser, Ala, Val or Gly was substituted foreach of the three Cys residues, were analyzed using calorimetry.The mutants were less stable than the wild type, indicatingthat Cys residues contribute greatly to the stability of the subunit. In most cases, a large decrease in denaturation enthalpywas observed, compensated for by the denaturation entropy toa major extent. The extent of changes in the denaturation Gibbsenergy and denaturation enthalpy varied greatly depending onboth substituting residues and positions. Of all the mutantproteins, the Cys154Ser mutant showed the greatest decreasein denaturation enthalpy; its denaturation enthalpy was halfthat of the wild type, and was considerably repaired by addinga ligand of the subunit. Because the enthalpy of ligand bindingto Cys154Ser in the native state did not change. it seems thatthe decrease in the denaturation enthalpy of Cys154Ser and itsrecovery by ligand binding are caused by conformational changesin the denatured state due to the mutation.     

High resolution transmission electron microscopy of Sm-Co based permanent magnets

Interface microstructures between rhombohedral Sm₂Co₁₇ and hexagonal SmCo₅ phases in a sintered permanent magnet of Sm(Co_0.675Fe_0.175Ni0.05Cu_0.1)₇ have been investigated by edge-on observations with the many-beam imaging technique. In the specimen annealed at 800°C for 4 h which shows a maximum magnetic coercivity, the interface boundaries were coherent accompanying the lattice distortion; the habit planes were parallel to the {101}_2:17 and {111}_1:5 planes with the orientation relationship of (0001)_2:17//(0001)_1:5 and [1010]_2:17//[1120]_1:5. In the specimen annealed for 150 h which shows a lower coercivity, the interface boundaries were characterized with regular alignments of interfacial edge dislocations. The observed interface structures were discussed in connection with the change in magnetic properties.     

A 400 μm thickness diamond-like carbon preparation

A 400 μm thick diamond-like carbon (DLC) film was prepared on an aluminum alloy (A5052) substrate by a hybrid process of plasma-based ion implantation and deposition using toluene as a precursor gas. The plasma-based ion implantation during deposition relaxed the residual stress in DLC film to almost 0, indicating the production of stress-free DLC. The carbon ion implantation from the methane and acetylene plasmas to the substrate surface, prior to deposition, resulted in an interface graded in carbon composition as well as the formation of amorphous-like structure at the carbon ion-implanted layer that should work as a buffer for stress-relaxation. As a result, a supra-thick DLC film more than 400 μm in thickness was prepared on the substrate.     

F-type icosahedral phase and a related cubic phase in the Al-Rh-Cu system

An F-type icosahedral phase and a related cubic phase (composition of Al_66.1Rh_21.5Cu_12.3, lattice constant a=1.5380(2) nm, and space group of Fm3) were observed in the Al₆₃Rh_18.5Cu_18.5 alloy by transmission electron microscopy (TEM). The structure of the Al-Rh-Cu cubic phase was determined by single-crystal X-ray analysis. A high-resolution electron microscopic image of the Al-Rh-Cu cubic phase is presented together with a simulated image. The structure of the cubic phase can be described by two types of atom clusters, which have outer shells with icosahedral symmetry. It is suggested that the structure of the Al-Rh-Cu cubic phase is helpful for understanding the structure of the i-Al-Rh-Cu F-type icosahedral quasicrystal.     

Preparation of nano‐ and microparticles through self‐assembly of azobenzene‐pendent ionomers

The particle formation of azobenzene‐containing ionomers, through self‐assembly, in aqueous media (THF/H₂O solvent) was studied. The ionomers were synthesized by copolymerization between azobenzene‐pendent methacrylate and methacrylic acid. It was revealed by UV–vis spectra and light scattering measurements that the extent of H‐aggregation of the azobenzene units first decreased, and then increased with increasing volume fraction of H₂O of the solvent. The H₂O fraction at which the extent of H‐aggregation began to increase became lower, when the copolymers contained more azobenzene units. Colloidal particles were prepared by slow addition of various concentrations of aqueous NaOH to the copolymer THF solutions. The hydrodynamic diameters of the particles obtained by the procedures were several hundreds of nanometer. When the azobenzene unit content in the copolymer was smaller, the diameters of the particles became smaller. When the colloidal particles dispersions were cast on a carbon sheet and dried, the particles aggregated and formed larger spherical particles, with diameters of several micrometers. The size of the particles obtained by the drying process became smaller, when higher concentrations of aqueous NaOH solutions were used. Therefore, the particle sizes were controlled by the azobenzene units content in the copolymers and the concentration of aqueous NaOH solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3913–3918, 2006     

Influence of Spark Plasma Sintering (SPS) Conditions on Transmission of MgAl2O4 Spinel

The effects of the spark plasma sintering (SPS) parameters, such as heating rate α, temperature T and soak time t_s, and impurities on in‐line transmission T_in were examined in MgAl₂O₄ spinel. The SPS processing at T = 1300°C for t_s = 20 min with a low heating rate of α = 10°C/min is a preferable condition for attaining higher T_in. For the higher T or the longer t_s, grain coarsening enhanced the coalescence of residual pores and second phase precipitation, resulting to the limited T_in even at the slow α. Although the lower T and longer t_s attained fine and dense microstructure simultaneously, the maximum T_in was limited to about 50%. The limited transmission, particularly in the visible range, can be ascribed to the discoloration caused by the carbon contamination. The carbon contamination arose from the preexisting trace CO₃ impurities, irrespective of the SPS conditions. For the higher α, which is the primary advantage of the SPS technique, the additional carbon contamination occurred from the paper/die and remained as glassy carbon in the matrix. To attain higher T_in by the SPS technique, the lower α and T, and the shorter t_s should be utilized after removing the impurities.     

Neither too sweet nor too sour: problem peers, maternal control, and problem behavior in African American adolescents

This study examined whether maternal control protects African American adolescents from the negative influence of problem peers. Two forms of control were examined, behavioral control and psychological control. It was hypothesized that there would be a curvilinear relation between control and adolescent problem behavior, with the strength of the relationship and the amount of control optimal for adolescent development varying by the level of peer problem behavior. In general, data supported this model, particularly in regard to behavioral control, where the predicted curvilinear interaction occurred even after controlling for initial levels of problem behavior. The predicted curvilinear interaction between psychological control and peer problem behavior was statistically significant if initial levels of problem behavior were not controlled for but was not significant after controlling for initial problem behavior. These findings suggest that high-quality parenting can play a modest but critical role in the face of environmental adversity.     

Near-Stoichiometric interaction between the non-specific lipid-transfer protein of the yeast Candida tropicalis and peroxisomal acyl-coenzyme A oxidase prevents the thermal denaturation of the enzyme in vitro

A 14-kDa peroxisomal-matrix protein, named PXP-18, of the yeast Candida tropicalis is a structural and functional homologue of the mammalian nonspecific lipid-transfer protein (identical to sterol carrier protein-2). PXP-18 protected acyl-coenzyme A oxidase (ACO), the rate limiting enzyme of the peroxisomal β-oxidation of fatty acids, from thermal inactivation at 48°C or 70°C. This effect was dose-dependent and not replaceable either by chicken egg white lysozyme, which is similar to PXP-18 (insofar as it is basic, small, and monomeric), or by bovine serum albumin, a carrier of lipids in the blood. ACO was irreversibly denatured by heat treatment at 70°C for 15 min. However, when ACO and PXP-18 were similarly heat-treated, they formed a large complex at a molar ratio of PXP-18 to ACO subunit that was about one, independent of their initial ratio. This near-stoichiometric complex had ACO activity after a 500-fold dilution and was accompanied by ACO that was free of PXP-18 and indistinguishable from native ACO in size and activity. PXP-18 also protected urate oxidase, another peroxisomal enzyme, from inactivation at 66°C for 15 min and facilitated the renaturation of ACO denatured by 2 M urea. These results indicated that PXP-18 is active in modulating the structure of peroxisomal enzymes in vitro. It is possible that PXP-18 functions as a stress protein or as a part of the system that keeps peroxisomal proteins intact.