Random-coiled conformation of polypeptide chains

Summary Random-coiled conformation of poly(L-leucine), which has -branched side-chain, was theoretically analyzed by a conformational energy calculation based on intra-residue interactions. Calculated characteristic ratio 7.62 was obtained by using the transformation matrix statistically averaged over the entire side-chain conformational space of L-Leu residue. This value is smaller than those of poly(L-phenylalanine) (11.24) and poly(L-tyrosine) (12.33) which have -branched side-chain.     

Dendrimer-immobilized culture surface as a tool to evaluate formation of cellular cytoskeleton of anchorage-dependent cells

Anchorage-dependent cultivation of human epithelial and keratinocyte cells was carried out on surfaces modified with synthesized dendrimers. Notable elongation of the epithelial cells was recognized on the culture surface immobilized with a dendrimer having D-glucose as a functional ligand, but not when a dendrimer having L-glucose was used or when the dendrimer was ligand-free. This morphological change was attributable to a temporary grasping of the cells at the D-glucose moiety via a glucose transporter-mediated mechanism present in the cell membrane. Following visualization of the actin filaments of the cells, it was considered that the cellular elongation on the D-glucose-bound dendrimer surface reflected the degree of formation of the cellular cytoskeleton. The cellular roundness was calculated by means of image analysis of the individual cells and employed as a parameter to evaluate the formation of the cellular cytoskeleton. In the culture of keratinocytes on the D-glucose-bound dendrimer surface, it was demonstrated that the decrease in the ratio of elongated cells (i.e., cells with a low roundness value) was correlated with the deterioration in the growth potential associated with cellular senescence.     

Effects of hydrophilicity of crosslinker on membrane properties of poly(N-hydroxyethyl-L-glutamine) hydrogels

Summary Poly(N-hydroxyethyl-L-glutamine) (PHEG) hydrogels were prepared by aminolysis of poly( -benzyl L-glutamate) with 2-aminoethanol and hydrophobic or hydrophilic crosslinkers, and the effect of the hydrophobicity of the crosslinkers was evaluated. The swelling properties, tensile properties and enzymatic degradation behavior were studied in phosphate buffered saline (PBS). The swelling ratio and degradation rate of these hydrogels were highly dependent on the hydrophobicity of the crosslinkers, while tensile properties were dependent on the swelling ratio, but not on the hydrophobicity of the crosskinkers.     

Spectral interferometric microscope with tandem liquid-crystal Fabry-Perot interferometers for extension of the dynamic range in three-dimensional step-height measurement

The maximum measurable range of a spectral interference microscope depends on the coherence length of the light transmitted by its tunable spectral filter. To achieve a large range in step-height measurement we have developed a new tunable spectral filter that uses tandem liquid-crystal Fabry-Perot interferometers (LC-FPIs), which can simultaneously attain both a high spectral resolution and a large tuning range. Fringe visibility measurements were carried out, and it was found that the coherence length of the light transmitted through tandem LC-FPIs is two times larger than that transmitted through a single LC-FPI. Using this novel tunable spectral filter, we developed a new spectral interference microscope for the measurement of three-dimensional shapes of discontinuous objects. Experimental results of step-height measurements both with a single LC-FPI and with tandem LC-FPIs are presented for a combination of standard steel gauge block sets with 1-, 99-, and 100-microm steps. A large range (1-100 microm) of measurement with submicrometer resolution was achieved with tandem LC-FPIs that was not possible with our previous system in which a single LC-FPI was used.     

High-temperature pyrolysis of ceramic fibers derived from polycarbosilane–polymethylhydrosiloxane polymer blends with porous structures

The polymer blends of PCS (polycarbosilane) and PMHS-h (polymethylohydrosiloxane with high molecular weight) were prepared by freeze-drying process of mixed benzene solution. Melt viscosity, mass loss, and gas evolution from prepared polymer blends were analyzed. A polymer blend of HSah15 (15 mass% PMHS-h to PCS) was melt-spun to fiber form, curing by thermal oxidation and pyrolyzed at various temperatures up to 1773 K. The obtained fibers were investigated by tensile tests, FE-SEM (field emission scanning electron microscope) observation, and XRD (X-ray diffraction) analysis. After pyrolysis at 1273 K, there were no pores in the cross section of the fiber derived from pure PCS; however, there were amounts of pores in the cross sections of the fiber derived from HSah15. After pyrolysis at 1773 K, the coarse β-SiC (silicon carbide) crystals were formed on the outside surface of the fiber derived from pure PCS; however, no remarkable β-SiC crystal were formed on the outside surface of the fiber derived from HSah15.     

Structure Analysis of Molten Ba–Ge Alloys Using Electrostatic Levitation Technique Combined With High-Energy X-Ray Diffraction

High-energy synchrotron X-ray diffraction experiments were performed for clathrate-forming barium–germanium (Ba–Ge) alloys in the liquid state near the eutectic composition. The accurate structure information of highly reactive melts has been obtained by applying electrostatic levitation technique as a containerless method. The structure information obtained from the reverse Monte Carlo simulation suggests that the short-range ordering between the Ge atoms occurs with the addition of Ba atoms in the liquid Ba–Ge alloys. This can be associated with the formation of the cage-like structure composed of the Ge atoms in the liquid alloys near the eutectic composition.     

The data-driven microprocessor

Processor performance limitations that can be solved by data-flow processing are discussed. Data-flow-based software and multiprocessors are considered. A data-driven, 32-bit, five-chip set that performs real-time signal and distributed parallel processing without a system clock or centralized control unit is presented. Language processing and processor applications are examined     

VLSI implementation of a variable-length pipeline scheme fordata-driven processors

A VLSI-oriented variable-length pipeline structure for data-driven processors is presented. Ordinary inline pipelines have the problem of minimizing the average total processing time through the pipeline, since subdivision of a function along the pipeline is usually optimized for the most complex operations in spite of the fact that simpler operations need fewer stages. As a solution to this problem, a variable-length pipeline scheme in which data go through only the necessary stages according to information contained within is proposed. The scheme has been implemented on a test chip to verify performance. The chip demonstrated a minimum fall-through time (data transmission time from input to output) of 14.4 ns and a data transmission rate in the pipeline of 59 megaword/s (that is, 1/16.9 ns) as a first-in first-out (FIFO) store. By modifying the data transfer control and allocating the processing functions corresponding to the data interval of 16.9 ns, this scheme is applicable as a high-performance processing unit for data-driven processors     

Chemical durability of a superconducting oxide YBa2Cu3Ox in aqueous solutions of varying pH values

The chemical durability of a superconducting oxide YBa₂Cu₃O _x in the aqueous solution was investigated as a function of pH value by measuring the amount of leaching of the cations in the solution by inductively coupled plasma (ICP) analysis. The chemical durability of YBa₂Cu₃O _x was very low in highly acidic solutions of pH ca, 1, where the cations were dissolved in the same cation ratio as that of the compound. In an ion-exchanged water and NaOH solution, barium ions were leached out preferentially and almost no yttrium and copper ions were leached out. When NH₄OH was used as a basic reagent, the amounts of barium ions leached out were higher than in the NaOH solution of the same pH value and the dissolution of copper ions was observed, unlike in the NaOH solution of the same pH value. These observations were explained in terms of the chemical stability of individual oxide components.     

Administration-time-dependent effects of diltiazem on the 24-hour blood pressure profile of essential hypertension patients

Cells of the central nervous system (CNS) normally do not express detectable levels of major histocompatibility complex (MHC) Class I antigens. However, MHC Class I expression can be induced after virus infection. We tested the hypothesis that virus-induced Class I expression is mediated by lymphocytes or cytokines using lymphocyte- and cytokine-deficient mice. We used Theiler's murine encephalomyelitis virus (TMEV), which induces CNS demyelination that maps genetically to the D region of MHC Class I and is associated with high levels of Class I products. TMEV infection of severe combined immunodeficiency (SCID) and recombination activation gene-1-deficient mice, which lack B and T lymphocytes, resulted in equivalent H-2D and H-2K expression in brain and spinal cord, according to analysis of the area and intensity of immunoperoxidase staining. Class I antigens were demonstrated as early as 6 hours after infection, and they were more widely distributed than viral RNA, indicating that expression was induced indirectly via a soluble factor. To determine whether cytokines induced the expression, we infected mice lacking receptors for interferon-alpha/beta (IFN-alpha/beta R (-/-)), interferon-gamma (IFN-gamma R(-/-)), and tumor necrosis factor-alpha (TNFRp55(-/-)). TMEV-infected IFN-gamma R(-/-) and TN-FRp55(-/-) mice expressed Class I antigens in the CNS, whereas IFN-alpha/beta R(-/-) mice did not, establishing that IFN-alpha/beta mediated the expression. In contrast to the equivalent expression in SCID mice, we observed greater area and higher intensity of H-2D versus H-2K antigens in infected SCID mice reconstituted with normal spleen cells. Collectively, the data indicate that after TMEV infection, early generalized MHC Class I expression is mediated by IFN-alpha/beta independently of lymphocytes, but the differential regulation of H-2D over H-2K may be controlled by B and/or T lymphocytes.