Phase-shift analysis of electric conductance through nanostructure bridges

We present our theoretical studies of electric conductance through nanostructure bridges. A simple expression of the electric conductance is obtained by using the phase-shift analysis. The phase-shifts are given by solving the characteristic equation obtained by extending the method applied to the single impurity problem in the metal. It is shown that the importance of the effect due to multiple orbitals in nanostructures. The conductance of the chain consisting atoms with sp_z character such as Al is given.     

Synthesis of new 3-cyanoacetamide pyrrole and 3-acetonitrile pyrrole derivatives

A new fused heterocyclic derivatives of pyrrole containing acetonitrile or cyanoacetonitrile moiety at 3-position is described by a one-pot multicomponent reaction. The reaction of dimedone, various aniline, aryl glyoxal with malononitrile/ethyl cyanoacetate/methyl cyanoacetate under mild conditions. The present method does not involve any hazardous organic solvents or catalysts. The significant features of this method are readily available starting materials, good yields, and easy purification.     

Ultrasensitive Simultaneous Quantification of Nanomolar Level of Cd and Zn by Cathodic Adsorptive Stripping Voltammetry in Some Real Samples

A novel, simple and sensitive adsorptive stripping voltammetry method was developed for simultaneous determination of Cd and Zn using N‐Nitrozo‐N‐phenylhydroxylamine (Cupferron) as a selective complexing agent. Cadmium and zinc metals gave peaks that were distinctly separated by 450–1200 mV, allowing their determination over a wide range of concentrations. The influence of pH and the nature of supporting electrolytes, concentration of ligand, preconcentration time and applied potential were investigated. The detection limits were 0.058 ng/mL for Zn and 0.092 ng/mL for Cd, and the RSD at a concentration level of 50 ppb, were 1.8–2.1 % for both zinc and cadmium, respectively. The method was applied to the determination of cadmium and zinc in blood, drug, food and water samples with the satisfactory results.     

Measurement of the neutron beam polarization of BL05/NOP beamline at J-PARC

We measured the neutron beam polarization of the BL05/NOP (Neutron Optics and Physics) beamline at J-PARC with an accuracy of less than 10⁻³ using polarized ³He gas as a neutron spin analyzer. Precise polarimetry of the neutron beam is necessary to understand the beamline optics as well as for the asymmetry measurements of the neutron beta decay, which are planned in this beamline.     

Anomalous behavior of linear resistivity arising in intergrain ordering process of weak-sintered ceramic system YBa2Cu4O8

Faint electric resistivity behavior is searched experimentally near and below intergrain ordering temperature of weakly sintered ceramic YBa₂Cu₄O₈ (Y124). For this purpose, a new method to detect linear and nonlinear resistivity sensitively by combination of pulse delta method and numerical Fourier-transformation has been designed. Making use of the experimental system for several weak sintered Y124 samples, it is revealed that linear resistivity just above the intergrain ordering point first drops toward zero steeply with decreasing temperature, and then turns abruptly upward to forms faint maximum at lower temperature. Such a novel behavior of ‘revival of resistivity’ is confirmed to be reproducible, and considered to be an essential frustration effect for d-wave type grain system with irregular or inhomogeneous ceramic structure.     

Synthesis and characterization of polymer linked copper(I) bis(N‐heterocyclic carbene) mechanocatalysts

In this paper, the synthesis and characterization of a series of latent polymeric bis(N‐heterocyclic carbene) (NHC) copper(I) complexes is reported, which can be activated for the copper(I)‐catalyzed azide/alkyne cycloaddition (CuAAC) via ultrasound. To prove the influence of chain length and nature of the polymer towards the activation, poly(isobutylene) (PIB), poly(styrene) (PS) and poly(tetrahydrofuran) (PTHF) are synthesized via living polymerization techniques (LCCP, ATRP, CROP) obtaining different chain lengths (from 2500 to 9000 g/mol), followed by quaternization with N‐methylimidazole, generating the corresponding N‐methylimidazolium‐telechelic polymers. The deprotonation of these macroligands via strong bases like sodium tert‐butoxide (NaO^tBu) or potassium hexamethyldisilazide (KHMDS) yields the free N‐heterocyclic carbenes (NHCs), which are used to coordinate to tetrakis(acetonitrile)copper(I) hexafluorophosphate, forming the final polymer‐based mono‐ and bis(N‐methylimidazole‐2‐ylidene) copper(I)X complexes. The structural proof of these complexes is accomplished via ¹H‐NMR spectroscopy, MALDI‐TOF‐MS and GPC‐techniques. The activation of the copper(I) biscarbene catalysts by ultrasound is studied by GPC, revealing the cleavage of one shielding NHC‐ligand. The initial catalytic latency and the via ultrasound introduced catalytic activation is successfully demonstrated monitoring a CuAAC “click” reaction of benzyl azide and phenylacetylene by in situ ¹H‐NMR spectroscopy introducing thus “click” conversions up to 97%. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3893–3907     

Development of upper bound technique for analysis of fracture in metal forming

Summary An attempt is made to modify the plasticity theory for compressible materials and then to derive the upper bound theorem or the second extremum principle which incorporate normal velocity discontinuity; this discontinuity is considered to be a measure of fracture. The theorem is applied to predict the occurrence of fracture, central bursting in extrusion or drawing. The occurrence of fracture appears to depend on the value of the parameters in the theorem; these parameters may be related to ductility or workability of the material in question. The upper bound technique is then applied to multi-stage extrusion of a carbon steel for which the values of the parameters are given with some assumptions. It is thus shown that the stage at which central bursting occurs agrees with experimental results and that it apparently depends on the extrusion condition.

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Ein obere-schranken-konzept zur bestimmung von bruchvorgängen bei der umformung von metallen

Übersicht Es wird der Versuch unternommen, mit einer modifizierten Plastizitätstheorie für kompressible Werkstoffe den Obere-Schrankensatz bzw. das zweite Extremum-Prinzip herzuleiten, wenn die Normalgeschwindigkeit auf Sprungflächen unstetig ist. Diese Unstetigkeit wird als Indikator von Bruchvorgängen angesehen. Angewandt wird diese Hypothese auf die Vorhersage des Bruchs, d. h. der Materialtrennung im Kern beim Durchdrück- bzw. Durchziehverfahren. Das Auftreten von Brüchen erweist sich als abhängig von den Parametern des Ansatzes. Diese Parameter lassen sich mit der Umformbarkeit des Materials in Zusammenhang bringen. Angewandt wird das Obere-Schranken-Konzept auf das mehrstufige Durchpressen eines Kohlenstoff-Stahls, für den die Parameterwerte mit Hilfe einiger Parameterwerte festgelegt werden. Davon ausgehend wird gezeigt, daß die Preßstufe bei Materialtrennung mit experimentellen Ergebnissen übereinstimmt und offensichtlich von den Durchpreßbedingungen abhängt.