Morphological study of the wear of crystalline polymers II: Isotactic poly(propylene)

The morphology of the worn surface and wear debris of isotactic poly(propylene) (PP) slid against steel in air and water was studied. From electron micrographs, electron diffraction patterns and X-ray diffraction patterns it was found that both the worn surface and the wear debris had a smectic structure. Plastic deformation of the surface of PP took place during frictional contact both in air and in water, giving rise to the formation of thick meandered fibrous aggregates with their longitudinal axes nearly perpendicular to the sliding direction and thin fibrils aligned parallel to the sliding direction.     

Circular dichroism of poly(β-benzyl-l-aspartate) films in the α, β and ω conformations

The conformations of poly(β-benzyl l-aspartate) (PBLA) in film were studied by means of circular dichroism (c.d.). Films of PBLA show c.d. which is related to the benzyl chromophores of this polypeptide. The magnitude and sign of the c.d. of the benzyl chromophores depend on the conformation i.e. α-helix, ω-helix or β-form. The aromatic c.d. of the left-handed α-helix or the left-handed ω-helix is negative in sign, and that of the β-form is positive in sign. The absolute magnitude of the c.d. of PBLA is much larger in the ω-helical conformation than in the α-helical or the β-conformations. In the left-handed α-helical PBLA (α-PBLA), the positive dichroism band of the $\text{n?π1}$ peptide electronic transition is observed at about 226 nm. When the α-PBLA is converted to the left-handed ω-helical PBLA (ω-PBLA), the band at 226 nm shifts to 224 nm, and its magnitude becomes much smaller. In the β-form PBLA (β-PBLA), this band is negative in sign and observed at 223 nm. The absolute magnitude of the c.d. relative to this electronic transition follows the order: β-form < ω-helix < α-helix.     

An experimental study of the insulated dipole antenna immersed in a conducting medium

The driving-point admittance and the amplitude and phase distributions of the current referred to the driving-point were measured for an insulated cylindrical antenna immersed in a conducting medium. The ratiosigma/omegaepsilon_{r}epsilon_{0}of the conducting medium was varied fromsigma/omegaepsilon_{r}epsilon_{0}= 0.036to 8.8, a range which includes a variety of media such as poor insulators, the ionosphere, plasmas, dry earth, wet earth, lake water and sea water. The antenna heightbeta hin radians was varied frombeta h=0.1throughbeta h=2piat intervals of 0.1. The thickness of the insulator was varied fromb/a = 1.25tob/a = 12.0whereais the radius of the antenna andbthe radius of the insulator. Measurements have also been made of the admittance, current and phase distributions along an insulated antenna with a conductive top load, that is, one whose tip is in direct contact with the conducting medium. It is found that when the tip of the antenna is in direct contact with the conducting medium, the current increases almost linearly as the end of the antenna is approached. This is quite unlike the decaying sinusoidal distribution on the completely insulated antenna. In a general sense, the experimental results are in fair agreement with an approximate theoretical expression for the admittance of an insulated antenna immersed in a highly conducting solution. The approximate theory is based on the driving-point admittance of a coaxial line whose outer conductor is imperfectly conducting and infinite in extent.     

Identification of crack path of inter- and transgranular fractures in sintered silicon nitride by in situ TEM

Inter- and/or transgranular crack paths in sintered silicon nitride (Si3N4) during fracture were investigated by in situ straining experiments in a transmission electron microscope at room temperature, using a high-precision micro-indenter. By this technique, cracks introduced in an in situ manner were observed to propagate in the grain interior and along grain boundaries. High-resolution electron microscopy (HREM) observation revealed that the crack propagation takes place at an interface between Si3N4 grains and an intergranular glassy film (IGF) in the case of intergranular fractures. According to the results by previous molecular dynamics simulations, a number of dangling bonds are present at the Si3N4/IGF interface, which should result in the observed fracture behavior at the interface. On the other hand, the crack path introduced during transgranular fracture of Si3N4 grains was found to be sharp and straight. The observed crack propagated towards [1120] inside the Si3N4 grain with the crack surface parallel to the (1100) plane. The HREM observations of crack walls revealed them to be atomically flat. The atomic termination of the crack walls was identified in combination with image simulations based on atomic models of the cleaved crack walls.     

Enhancement of the activities with feedstream doping by tetrachloromethane in the oxidative dehydrogenation of propane on α-magnesium pyrovanadate

The oxidative dehydrogenation of propane to propylene has been investigated on -magnesium pyrovanadate (Mg₂V₂O₇) at 723 K in the presence and absence of tetrachloromethane (TCM). Under the present conditions, the conversion of propane and the selectivity to propylene were 5.0 and 74.5%, respectively, in the absence of TCM while those were 14.0 and 70.2%, respectively, upon addition of a small amount of TCM (P(TCM) = 0.34 kPa) into the feedstream on the catalyst. The conversion of propane on Mg₂V₂O₇ without oxidant in the presence and absence of TCM revealed that a contribution of lattice oxygen in the catalyst to the oxidation was strongly controlled by the addition of TCM, resulting in the enhancement of the activity with TCM.     

A 385–500 GHz SIDEBAND-SEPARATING (2SB) SIS MIXER BASED ON A WAVEGUIDE SPLIT-BLOCK COUPLER

We have developed a 385–500 GHz sideband-separating (2SB) mixer, which is based on a waveguide split-block coupler at the edge of the H-plane of the 508 μm × 254 μm (WR 2.0) waveguide, for the Atacama Large Millimeter/submillimeter Array (ALMA). An RF/LO coupler, which contains an RF quadrature hybrid, two LO couplers, and an in-phase power divider, was designed with the issue of mechanical tolerance taken into account. The RF/LO coupler was measured optically with a microscope and electrically with a submillimeter vector network analyzer. The image rejection ratio (IRR) and the single-sideband (SSB) noise temperature of the receiver using the RF/LO coupler have also been measured. The IRR was found to be larger than 8 dB and typically ～ 12 dB in the 385–500 GHz band. The SSB noise temperature of this receiver is 80 K at the band center, which corresponds to 4 times the quantum noise limit (hf/k) in SSB, and 250 K at the band edges.     

Electrode reaction of the Np3+/Np couple in LiCl–KCl eutectic melts

The electrochemical behaviour of the Np³⁺/Np couple in the LiCl–KCl eutectic salt was investigated by electromotive force measurements, cyclic voltammetry and chronopotentiometry in the temperature region between 723 and 823 K. The standard redox potential of the Np³⁺/Np couple vs Ag/AgCl (1.00 wt %) was measured and given by the equation, E _Np ³⁺ _/Np ^° = –2.0298 + 0.000706 T, where E is in V and T in K. The electrode reaction of the Np³⁺/Np couple was almost reversible under the conditions studied. The diffusion coefficient of Np³⁺, D _Np ³⁺, in the LiCl–KCl eutectic melts between 723 and 823 K was represented by the equation, D _Np ³⁺ = 2.22 × 10^–6 – 6.88 × 10^–9 T + 5.60 × 10^–12 T ² cm² s^–1. The adsorption and desorption peaks of Np at the Mo working electrode caused by underpotential deposition were also observed in the cyclic voltammograms, and the work function of Np was evaluated as 3.04 eV by peak analysis of the cyclic voltammograms.     

Advancing Small‐Molecule‐Based Chemical Biology with Next‐Generation Sequencing Technologies

Next‐generation‐sequencing (NGS) technologies enable us to obtain extensive information by deciphering millions of individual DNA sequencing reactions simultaneously. The new DNA‐sequencing strategies exceed their precursors in output by many orders of magnitude, resulting in a quantitative increase in valuable sequence information that could be harnessed for qualitative analysis. Sequencing on this scale has facilitated significant advances in diverse disciplines, ranging from the discovery, design, and evaluation of many small molecules and relevant biological mechanisms to maturation of personalized therapies. NGS technologies that have recently become affordable allow us to gain in‐depth insight into small‐molecule‐triggered biological phenomena and empower researchers to develop advanced versions of small molecules. In this review we focus on the overlooked implications of NGS technologies in chemical biology, with a special emphasis on small‐molecule development and screening.     

Cloning and sequencing of cDNA and genomic DNA encoding serine carboxypeptidase of Fusarium moniliforme that was copurified with phosphatase

A previous study [Yoshida, H. et al., J. Biochem., 140, 813-823 (2006)] revealed that a protein of unknown nature was copurified with PDM phosphatase of Fusarium moniliforme. In this study, the identity of this protein was investigated. The results of homology search for the tryptic peptides derived from the purified preparation of PDM phosphatase strongly suggested that it might be serine carboxypeptidase. In fact, carboxypeptidase activity was demonstrated in the preparation and partial separation of carboxypeptidase from PDM phosphatase was achieved by gel filtration high-performance liquid chromatography. Cloning and sequencing of the full-length cDNA encoding the carboxypeptidase was successfully conducted. The cDNA possessed an open reading frame for a protein of 575 amino acid residues with a molecular mass of 64,650 Da, which was highly homologous to certain fungal serine carboxypeptidases. Comparison of the deduced amino acid sequence with the N-terminal sequence of the separated carboxypeptidase revealed that the mature enzyme starts at serine 56 of the precursor and has a molecular mass of 58,487 Da. Cloning and sequencing of the genomic DNA corresponding to the cDNA demonstrated that the gene of carboxypeptidase consists of four exons. A limited number of close homologs of F. moniliforme carboxypeptidase were detected among fungi by homology search and their evolutionary relationship was discussed.     

Tracking control for industrial robot using notch filtering system with little phase error

This paper proposes a new method for generation of a position reference that has both vibration suppression performance and fast tracking performance for industrial robots. It is important for industrial robots to drive at high speed and with high accuracy. In such cases, vibration is generated. Conventionally, the notch filter is used in order to reduce vibration. It is able to eliminate the natural frequency component, but a reference phase error is generated. The reference phase error causes locus error in the robot. Therefore, the accuracy of the robot is degraded by using a notch filter. The proposed method overcomes this problem by using the compensation gain. The proposed compensation gain is used in order to calculate the reference phase error. Compensation of the reference phase error is attained by feedforward input. Numerical and the experimental results confirm that the proposed method is valid for reducing vibration phenomena and that it decreases the phase error. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 53–63, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.20931