Structural motif of phosphate-binding site common to various protein superfamilies: all-against-all structural comparison of proteinmononucleotide complexes

In order to search for a common structural motif in the phosphate-bindingsites of protein–mononucleotide complexes, we investigatedthe structural variety of phosphate-binding schemes by an all-against-allcomparison of 491 binding sites found in the Protein Data Bank.We found four frequently occurring structural motifs composedof protein atoms interacting with phosphate groups, each ofwhich appears in different protein superfamilies with differentfolds. The most frequently occurring motif, which we call thestructural P-loop, is shared by 13 superfamilies and is characterizedby a four-residue fragment, GXXX, interacting with a phosphategroup through the backbone atoms. Various sequence motifs, includingWalker's A motif or the P-loop, turn out to be a structuralP-loop found in a few specific superfamilies. The other threemotifs are found in pairs of superfamilies: protein kinase andglutathione synthetase ATPase domain like, actin-like ATPasedomain and nucleotidyltransferase, and FMN-linked oxidoreductaseand PRTase.     

Direct Electroplating of Lithium Cobalt Oxide Film on Platinum Substrate in 100°–200°C Aqueous Solution

Well crystallized, shape-formed, and electrochemically active lithium cobalt oxide (LiCoO₂) films are electroplated directly on an electron-conducting substrate in an aqueous solution using a soft solution processing that is economical, consumes less energy consuming, and is environmentally friendly. Although LiCoO₂ films are easily and economically prepared without any post-synthesis heat treatment, the estimated film properties show a possibility of using the deposited films as a cathode film for lithium rechargeable microbatteries. In addition, the soft solution processing reveals that an exact understanding of chemical reactions and the proper combination of the chemical reactions can create an advanced synthetic procedure.     

Self-organized lightwave network based on waveguide films for three-dimensional optical wiring within boxes

This paper presents core technologies for a self-organized microoptical system (SELMOS) within optoelectronic computers; mass-productive fabrication processes of waveguide films and new types of self-organized lightwave networks (SOLNETs) for three-dimensional (3-D) optical wiring with optical Z-connections. Waveguide films are fabricated by the built-in mask method, which is reusable and can construct surface-normal mirrors/filters at one time within photolithographic accuracy. Beveled core edge walls are made by the tilted ultraviolet (UV) exposure through the built-in mask using a photodefinable material. Near- and far-field patterns reveal that the walls act as micromirrors for optical Z-connections. SOLNET is a network consisting of self-organized coupling waveguides between misaligned optical devices. The self-organization is generated in a photorefractive material by self-focusing of the two write beams from the two devices. Direct SOLNET, where wavelengths of the write beam and the signal beam are the same, is demonstrated using a laser diode. Reflective SOLNET, where one of the two write beams is replaced with a reflected write beam from the edge of the coupled device, realizes two-beam-writing SOLNET in a one-beam-writing configuration. It is especially effective when the coupled device cannot transmit write beams. The proof-of-concept is demonstrated both theoretically and experimentally. These results indicate a possibility to form 3-D optical wiring simply in SELMOS.     

Structural Changes of Scandia-Doped Zirconia Solid Solutions: Rietveld Analysis and Raman Scattering

Powder X-ray diffractometry (XRD) and Raman scattering measurements were used to study the structural changes of compositionally homogeneous metastable ZrO₂ solid solutions induced by ScO_1.5 doping. The crystal structures of monoclinic, tetragonal, cubic, and rhombohedral (Sc₂Zr₇O₁₇, ß-phase) solid-solution phases have been refined by using the Rietveld analysis of the XRD data at room temperature of arc-melted ZrO₂- X ScO_1.5 ( X = 0, 2, …, 20, and 22 mol%) samples. The results can be interpreted as indicating that the structures of the monoclinic and tetragonal phases approach those of the tetragonal and cubic phases, respectively, by ScO_1.5 doping. Raman scattering, as well as XRD, was useful to investigate the phase assemblage. Moreover, we could obtain Raman spectra of the ß-phase probably for the first time.     

Monte Carlo simulation and measurement of nanoscale n-MOSFETs

The output characteristics of state-of-the-art n-MOSFETs with effective channel lengths of 40 and 60 nm have been measured and compared with full-band Monte Carlo simulations. The device structures are obtained by process simulation based on comprehensive secondary ion mass spectroscopy and capacitance-voltage measurements. Good agreement between the measured output characteristics and the full-band Monte Carlo simulations is found without any fitting of parameters and the on-currents are reproduced within 4%. The analysis of the velocity profiles along the channel confirms that the on-current is determined by the drift velocity in the source side of the channel. Analytic-band Monte Carlo simulations are found to involve an overestimation of the drain current in the nonlinear regime which becomes larger for increasing drain voltage and decreasing gate length. The discrepancy originates from a higher nonlinear drift velocity and a higher overshoot peak in bulk silicon which is due to differences in the band structures above 100 meV. The comparison between analytic-band and full-band Monte Carlo simulation therefore shows that the source-side velocity in the on-state is influenced by nonlinear and quasiballistic transport.     

Reliability aspects of man-machine interface

Issues related to the reliability of man-machine interfaces (MMIs) are discussed from a multi-faceted point of view. Reliability concerning the human operator, the user of MMIs, is discussed using the stimulator data obtained under abnormal plant conditions. Based on the analysis, requirements for MMI design are derived. Cognitive task analysis is also performed to derive design requirements related to human problem solving.Reliability of software, one of the major components of the MMI, is then discussed from the viewpoint of software diversity. Other issues are also discussed to reduce design and implementation errors in the software development process.An experience in carrying out the evaluation of MMIs, one of the critical issues in developing dependable MMIs, is presented to clarify the methodological issues to be solved in the future.The discussions included in this paper show the necessity for a multi-faceted approach to the reliability of MMI both as an integrated object and as a component in a complex human-machine system.     

Low-loss polymeric optical waveguides fabricated with deuteratedpolyfluoromethacrylate

Deuterated polyfluoromethacrylate which has high transparency, low birefringence and good processability was newly synthesized for use as optical waveguide materials, and both single-mode and multimode optical waveguides were fabricated using the polymer. The propagation loss and waveguide birefringence of the single-mode waveguides were as low as 0.10 dB/cm and -5.5×10^-6 at 1.31 μm, respectively. The propagation losses of the multimode waveguides were less than 0.02 dB/cm at both 0.68 and 0.83 μm, and 0.07 dB/cm at 1.31 μm     

Application of an Ion-Packing Model Based on Defect Clusters to Zirconia Solid Solutions: I, Modeling and Local Structure of Solid Solutions

Oxygen vacancies can be introduced into zirconia solid solution ZrO₂–MO _u ( u = 1 and 1.5) to maintain electroneutrality. Recently, the local structures around Zr⁴⁺ and M^{2 u +} ions in ZrO₂–MO _u solid solutions have been studied through EXAFS spectroscopy, diffuse scattering analysis, and single-crystal structure analysis. The present study constructs an ion-packing model for zirconia solid solutions based on some defect cluster models. The decrease of cell volume with the occurrence of vacancies is assumed to be expressed by decreasing the coordination number (CN) of cations around the vacancy. The distribution of CNs in a solid solution was calculated from a certain defect cluster model. The average interatomic distances, the average CN, and the short-range order parameters were calculated using this distribution of CNs. The local structures calculated from the model were compared with experimental data in the systems ZrO₂–MO_1.5 (M = Y, Gd, Yb, and Ca). In the ZrO₂–YO_1.5 system, the r (s–O) interatomic distance, where s represents Zr⁴⁺ or Y³⁺ and O represents O²⁻, decreased with Y content and therefore vacancy content. The probability of finding Y³⁺ around a vacancy increases with increasing yttria content from a comparison of the calculated results with the ones from recent EXAFS studies. The present model can qualitatively explain compositional and size dependences of the dopant on various local structures.     

Thyrotropic action of human chorionic gonadotropin

Hyperthyroidism or increased thyroid function has been reported in many patients with trophoblastic tumors. In these cases, greatly increased human chorionic gonadotropin (hCG) levels and suppressed TSH levels suggest that hCG has thyrotropic activity. Recent investigations have clarified the structural homology not only in the hCG and TSH molecules but also in their receptors, and this homology suggests the basis for the reactivity of hCG with the TSH receptor. The clinical significance of the thyrotropic action of hCG is now also recognized in normal pregnancy and hyperemesis gravidarum. Highly purified hLH binds to recombinant hTSH receptor and is about 10 times as potent as purified hCG in increasing cAMP. The beta-subunits of hCG and hLH share 85% sequence identity in their first 114 amino acids but differ in the carboxy-terminal peptide because hCG beta contains a 31-amino acid extension (beta-CTP). A recombinant mutant hCG that lacks beta-CTP showed almost identical potency to LH on stimulation of recombinant hTSH receptor. If intact hCG were as potent as hLH in regard to its thyrotropic activity, most pregnant women would become thyrotoxic. One of the roles of the beta-CTP may be to prevent overt hyperthyroidism in the first trimester of pregnancy when a large amount of hCG is produced by the placenta. Nicked hCG preparations, obtained from patients with trophoblastic disease or by enzymatic digestion of intact hCG, showed approximately 1.5- to 2-fold stimulation of recombinant hTSH receptor compared with intact hCG. This suggests that the thyrotropic activity of hCG may be influenced by the metabolism of the hCG molecule itself. Deglycosylation and/or desialylation of hCG enhances its thyrotropic potency. Basic hCG isoforms with lower sialic acid content extracted from hydatidiform moles were more potent in activating adenylate cyclase, and showed high bioactivity/immunoactivity (B/I) ratio in CHO cells expressing human TSH receptors. This is consistent with the finding that the beta-CTP truncated hCG with higher thyrotropic potency is substantially deglycosylated and desialylated in the beta-subunit relative to intact hCG because all four O-linked glycosylation sites occur within the missing C-terminal extension. The desialylated hCG variant also interacts directly with recombinant hTSH receptors transfected into human thyroid cancer cells. There is thyroid-stimulating activity in sera of normal pregnant women, and this correlates with serum hCG levels. The thyroid gland of normal pregnant women may be stimulated by hCG to secrete slightly excessive quantities of T4 and induce a slight suppression of TSH, perhaps being about 1 mU/L less than nongravid levels, but not high enough to induce overt hyperthyroidism. Maternal thyroid glands may secrete more thyroid hormone during early pregnancy in response to the thyrotropic activity of hCG that overrides the normal operation of the hypothalamic-pituitary-thyroid feedback system. Biochemical hyperthyroidism associated with hyperemesis gravidarum has been attributed to hCG. In patients with hyperemesis gravidarum, thyrotropic in serum correlated with hCG immunoreactivity, and the severity of vomiting as indicated by clinical and biochemical parameters correlated with the degree of thyroid stimulation. To understand the thyrotropic action of hCG, it is necessary to know whether hCG activates the same domain of the TSH receptor as does TSH. The identification of the molecular structure of the hCG isoform with the highest thyrotropic potency will resolve the enigma of gestational thyrotoxicosis and the hyperthyroidism associated with trophoblastic disease and hCG-producing tumors.