A simple estimation method for effective adaptation coefficient

A method was proposed in a previous article (CRA, 22, 240–258, 1997) to estimate the state of incomplete adaptation by using the effective chromatic adaptation coefficient α_min. The method could be applied to any experiment on chromatic adaptation using object-color or luminous-color stimuli, but its computational procedure was rather tedious. For this reason, the two simple methods, Methods I and II, are proposed to give the approximate estimates of α_min. Method I uses the corresponding reference color under reference illuminant to a test achromatic color under test illuminant. Method II uses the two kinds of relation equations between test adapting luminance and α_min. The estimates of α_min by each of the two methods agree fairly well with those given in the previous article to the three experiments studied. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 259–268, 1997     

Development of Nb-Ti cable with ultrafine filament and high-resistivity matrix for ac use

Superconducting ac machines such as transformers and reactors are expected to have an important role in future electric power transport lines. In these machines, superconducting coils are wound with superconducting cables that have low ac loss, stable ac quenching current, and high normal resistivity. We have developed Nb-Ti superconducting cables with ultrafine filaments and high-resistivity matrix for these coils. One such cable is a double-stranded round structure using 0.2-mm strands with 0.14-μm filaments and Cu-30wt%Ni as a matrix material. The 50-Hz quenching current without external magnetic field exceeds 1400 Arms. The ac loss is 15 kW/m³ at a transverse external magnetic field of 0.5 T, 50 Hz, and the normal resistivity is 0.21 Ω/m at 0 T, 10 K. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(2): 8–18, 1997     

Self-surface passivation of CdX (X = Se, Te) quantum dots

A small portion of a reaction mixture including unpurified CdX (X = Se or Te) quantum dots (QDs), in which unreacted Cd and Se ions were left together with coordinating solvents, was dropped into an organic solvent. The CdX QDs in this organic solution showed enhancement of photoluminescence (PL) efficiency, growth of particles, and focusing of size distribution for more than 10 h at room temperature (RT, -23 degrees C). These effects were attributed to passivation of QDs' surface by Cd and X ions present in the solution. No external energy source was used for these achievements; therefore, the process is termed as self-surface passivation. The self-surface passivation was reproduced using purified CdX QDs with additional Cd and X ions in an organic solvent. The self-surface passivation method was applied to RT-synthesized CdSe QDs, which is characterized by a broad PL spectrum (fwhm - 150 nm) for monodispersed QDs, to modify their emission characteristics. On self-surface passivation, the broad PL spectrum was narrowed (fwhm - 35 nm) and the QDs were grown. The X-ray diffraction measurements of RT-synthesized CdSe QDs and that subsequently aged in 1-butanol showed that crystallinity of the samples was improved on aging.     

Aqueous phase synthesized CdSe magic-sized clusters: solution composition dependence of adsorption layer structure

We report dispersion solution composition dependence of the adsorption layer structure and the physical and optical properties of aqueous phase-synthesized semiconductor nanoparticles (NPs). We synthesized cysteine (Cys)-capped CdSe NPs with well-defined core structures, dispersed them in a series of aqueous solutions with different compositions, and then investigated their adsorption layer structure and physical and optical properties. Each CdSe NP consisted of a (CdSe)33 or (CdSe)34 magic-sized cluster (d - 1.45 nm) core, a ligand-Cys shell, and an adsorption layer. The dispersion solution composition strongly affected the adsorption layer structure of the CdSe NPs. The solution with a composition close to that of the as-prepared solution stabilized the physical and optical properties of the NPs. The solution with a composition different from that of the as-prepared solution, however, resulted in large changes in their adsorption layer structure and thus their physical and optical properties. The solution composed of neutral or weakly charged Cys and Cd-Cys complexes led to the adsorption layer with low charge density and that destabilized the NPs. The solution containing only neutral or weakly charged forms of Cys, without Cd-Cys complexes, was favorable to the formation of a thick adsorption layer with low charge density and that destabilized the NPs. The amount of adsorbed Cys in the adsorption layer depended on the dispersion solution composition. However, the amount of adsorbed Cd-Cys complexes in the adsorption layer was almost constant regardless of the dispersion solution composition.     

A constitutive model of particulate-reinforced composites taking account of particle size effects and damage evolution

This paper deals with a constitutive model of particulate-reinforced composites which can describe the evolution of debonding damage, matrix plasticity and particle size effects on deformation and damage. An incremental damage model of particulate-reinforced composites based on the Mori–Tanaka’s mean field concept has been extended to consider the particle size effects by using the Nan–Clarke’s simple method. The particle size effect on deformation is realized by introducing dislocation plasticity for stress–strain relation of in situ matrix in composites, and the particle size effect on damage is described by a critical energy criterion for particle–matrix interfacial debonding. For composites containing particles of various sizes, the effects of particle size distribution is incorporated into the model. Influence of debonding damage, particle size and particle volume fraction on overall stress–strain response of composites is discussed based on numerical results.     

Effect of Lipase Activity and Specificity on the DAG Content of Olive Oil from the Shodoshima-Produced Olive Fruits

Olive oils have a higher relative diacylglycerol (DAG) content than other plant oils. The lipase in olive fruits is involved in DAG production and is directly related to the acidity of the olive oil. However, the lipase activity and positional selectivity have not been clarified. To investigate the properties of olive fruit lipase, olive fruits of the Mission variety harvested during mid-December of 2005 on Shodoshima Island (Japan) were stored at 20, 30 or 40 °C for 4 weeks. Changes in the acidity and acylglycerol content of the oils extracted from the stored fruits were analyzed. The acidity and DAG content of the olive oils increased due to triacylglycerol (TAG) hydrolysis during storage. sn-1,2-DAGs preferentially increased during the early stages of storage, indicating that the olive fruit lipase is enantioselective for the sn-3 position, while non-enzymatic isomerization of sn-1,2-DAGs was observed throughout the entire duration of storage. Kinetic analysis revealed that the enantioselectivity of olive fruit lipase for the sn-3 position was approximately four times greater than for the sn-1 position. The lipase was gradually inactivated at temperatures of 30 °C or higher, and the ratios of the rate constant for inactivation to TAG hydrolysis at the sn-3 position was 0.2, 13, and 23 at 20, 30, and 40 °C, respectively.     

Measurement of tongue–artificial nipple contact pressure during infant sucking

To clarify the motor function of the infant tongue during sucking, we developed an artificial nipple that contained multiple small built‐in force sensors integrated with a PC‐based system which is capable of measuring tongue–artificial nipple contact pressures in real time. The force sensor is a cantilever structure with a small, thin stainless steel beam where an all‐purpose foil strain gauge is attached to the surface of the beam. An artificial nipple made of an elastomer containing these sensors is connected through an amplifier and an A/D converter to a PC via a USB port. Using this system, measurements were taken in three infants whose oral feeding was well established and in one infant of low birth weight. The results from each force sensor showed a pressure waveform of a nearly simple harmonic motion that indicated a peristalsis‐like movement of the tongue; the sucking frequency was found to be about two times per second. In addition, in the low‐birth‐weight infant, the pressure changed as the infant grew. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Large-scale genome reorganization in Saccharomyces cerevisiae through combinatorial loss of mini-chromosomes

A highly efficient technique, termed PCR-mediated chromosome splitting (PCS), was used to create cells containing a variety of genomic constitutions in a haploid strain of Saccharomyces cerevisiae. Using PCS, we constructed two haploid strains, ZN92 and SH6484, that carry multiple mini-chromosomes. In strain ZN92, chromosomes IV and XI were split into 16 derivative chromosomes, seven of which had no known essential genes. Strain SH6484 was constructed to have 14 mini-chromosomes carrying only non-essential genes by splitting chromosomes I, II, III, VIII, XI, XIII, XIV, XV, and XVI. Both strains were cultured under defined nutrient conditions and analyzed for combinatorial loss of mini-chromosomes. During culture, cells with various combinations of mini-chromosomes arose, indicating that genomic reorganization could be achieved by splitting chromosomes to generate mini-chromosomes followed by their combinatorial loss. We found that although non-essential mini-chromosomes were lost in various combinations in ZN92, one mini-chromosome (18kb) that harbored 12 genes was not lost. This finding suggests that the loss of some combination of these 12 non-essential genes might result in synthetic lethality. We also found examples of genome-wide amplifications induced by mini-chromosome loss. In SH6484, the mitochondrial genome, as well as the copy number of genomic regions not contained in the mini-chromosomes, was specifically amplified. We conclude that PCS allows for genomic reorganization, in terms of both combinations of mini-chromosomes and gene dosage, and we suggest that PCS could be useful for the efficient production of desired compounds by generating yeast strains with optimized genomic constitutions.     

Positive patterning of ferritin and fibronectin molecules on silicon by the atomic force microscopic anodic oxidation technique

Oxide dots fabricated on silicon (111) by the Atomic Force Microscopy (AFM) anodic oxidation technique was used for the patterning of two different proteins namely, ferritin and fibronectin. Si surfaces were oxidized by the SC1 process and then modified with octadecyltrichlorosilane (OTS) for passivation. Oxide dots were fabricated by applying a bias voltage between the AFM probe and the silicon surface. Furthermore, surface functionalization of oxide dots was achieved through gamma-aminopropyltriethoxysilane (gamma-APTES) and glutaraldehye modification to establish a covalent bond between aldehydes and amino groups of protein molecules. Topographies after each modification steps were monitored by AFM. We were able to achieve positive patterning of ferritin molecules up to an average density of 6 x 10(9)/cm2 on gamma-APTES-covered dots, while 9 x 10(8)/cm2 of ferritin molecules remained on the OTS surface. In contrast to this observation, fibronectin molecules were patterned successfully only on oxide dots, and we did not observe any fibronectin molecules on the OTS surface.