Measurement of the magnetic field of resin-impregnated bulk superconductor annuli

Large single-grain bulk RE–Ba–Cu–O (RE: rare earth elements) superconductors can trap large fields exceeding several teslas and thus can function as very strong quasi-permanent magnets. We have found that the resin can penetrate into a bulk superconductor, when the sample was immersed in molten resin. Hence, resin impregnation was effective in improving mechanical properties. Three bulk superconductors‘ annuli with resin impregnation, each 50-mm i.d. and 80-mm o.d. was built and energized, by a field-cool method, to generate, in a bath of liquid nitrogen, a persistent trapped field of 1.62 T.     

Theoretical analysis of soil reaction on a lug of the movable lug cage wheel

The measurement of soil reaction forces on a lug of a movable lug cage wheel was carried out in a soil bin. To elucidate the experimental results, a theoretical analysis of soil reaction forces on the lug of the movable lug cage wheel was made by using an analysis of the lug trajectory and a modified theory in soil–vehicle mechanics. The existing theory was modified and adjusted by considering the actual lug trajectory and the soil trench made by the preceding lug. The results showed that the theoretical analysis gave a good representation of the reaction forces measured experimentally. The higher pull and lift forces of the movable lug cage wheel compared with those of the fixed lug wheel was supported by the theoretical analysis. Although the theoretical representation of soil reaction forces should be improved by further works, it is sufficiently accurate to estimate the performance of the movable lug cage wheels by the proposed theory.     

Correlation between film thickness and zinc defect distribution along the growth direction in an isotopic multilayer ZnO thin film grown by pulsed laser deposition analyzed using the internal diffusion method

Zinc self-diffusion along the growth direction was analyzed for the isotopic multilayer ZnO thin film ((⁶⁴ZnO/⁶⁸ZnO)₆⁶⁴ZnO) deposited by pulsed laser deposition. The isotopic distribution was measured using a secondary ion mass spectrometry. The amplitude of the ⁶⁴Zn abundance in the depth profile was reduced by annealing at 993 K for several hours due to interdiffusion between the ⁶⁴ZnO and ⁶⁸ZnO layers. The diffusion profiles at the isotopic interfaces were analyzed using a periodic equation. The obtained zinc self-diffusion coefficients at several isotopic interfaces along the growth direction showed that the self-diffusion coefficients increased towards the film/substrate interface. A similar trend was also found in the lateral direction. The variation among the self-diffusion coefficients was related to the film thicknesses at the analysis positions. Since zinc self-diffusion is controlled by a vacancy-mediated mechanism, the variation in zinc diffusivity along the growth direction can be attributed to the effect of compressive biaxial stress. These findings are useful for producing high-quality ZnO devices.     

Synthesis of l-α-phosphatidyl-d-myo-inositol 3,5-bisphosphate from d-glucose

Efficient synthesis of l-α-phosphatidyl-d-myo-inositol 3,5-bisphosphate was achieved from 1,2,5,6-diisopropylidene-d-glucose by utilizing ring-closing metathesis and catalytic OsO₄ dihydroxylation.     

Swern Oxidation of α-Ketols to α-Diketones1

The Swern oxidation of acyclic and cyclic α-ketols delivered α-diketones or the tautomeric diosphenols in good yield.     

Hydrogen-bonded network and enforced supramolecular cavities in molecular crystals: An orthogonal aromatic-triad strategy. Guest binding,molecular recognition,and molecular alignment properties of a bisresorcinol derivative of anthracene in the crystalline state

Abstract

Crystallization of an orthogonal resorcinol-anthracene-resorcinol compound 1a (host) from an ester solvent such as alkyl benzoate (guest) affords a 1:2 host-guest adduct 1a·2(ester). An essential aspect of the crystal structures of ethyl, propyl, and isobutyl benzoate adducts (space group, P2₁/n) and also that of methyl benzoate adduct (C2/c) is an extensive hydrogen-bonded network of host 1a, leading to a molecular sheet composed of hydrogen-bonded polyresorcinol chains and anthracene columns. This network generates well-defined, cyclophane-like supramolecular cavities, which incorporate two alkyl benzoate molecules in a highly selective manner via a combination of essential host-guest hydrogen-bonding and what may be called the cavity-packing effect. The selectivity factor between methyl benzoate (the lowest-affinity guest) and isobutyl benzoate (the highest-affinity guest) is 1:70 under competitive conditions. The actual geometry of the cavity is somehow dependent on and hence induced-fit adjustable to the guest structures by manipulating the intramolecular (anthracene-resorcinol dihedral angle) and intermolecular conformation (tilt angle between two hydrogen-bonded resorcinol rings) of compound 1a as well as the sheet-to-sheet distance. The adducts 1a·2(guest) can also be obtained by solid-state guest-exchange or guest-binding, respectively, using a preformed adduct or guest-free apohost dipped in an appropriate guest solvent. The methyl benzoate adducts obtained in these ways exhibit the same X-ray powder diffraction pattern as the genuine single-crystal obtained by direct crystallization of host 1a from methyl benzoate. Thus, even internal supramolecular cavities maintained by the hydrogen-bonded network are readily accessible to molecules in bulk solution. In addition, they undergo an induced-fit adjustment to a guest molecule newly added by the guest-exchange or the guest-binding process, during which the crystallinity is maintained. The potential use of symmetrical and divergent multiple hydrogen-bonding sites with an orthogonal aromatic spacer (orthogonal aromatic-triad strategy) is discussed in terms of a tool to construct a new class of porous organic crystals that show novel molecular recognition, crystalline-state guest-binding, and crystalline-phase molecular alignment properties.     

Model of the transmitted current oscillations in a dielectric capillary

In this work, we suggest a theoretical model that explains the interesting phenomenon of the regular oscillations of the current of ions transmitted through a dielectric capillary. The model is based on the assumption that upon the collision of ions with capillary wall, defects having a vacant state of electrons are generated on its surface. If the concentration of these defects reaches the value at which the wave functions of the electron vacancies overlap, a vacant zone of nonlocalized states appears, and the charge allowing noncontact transmission of ions drains quickly. In other words, the capillary closes.     

Strain energy function of swollen polybutadiene elastomers studied by general biaxial strain testing

The stress–strain behavior of polybutadiene elastomers with various degrees of swelling is investigated for general biaxial strain. Although a number of previous observations have suggested that the classical neoHookean (NH) model describes the uniaxial data of an elastomer in a highly swollen state, the NH model evidently fails to reproduce the biaxial data. This result indicates that the successful fit of the NH model for the uniaxial data of highly swollen elastomers, which has long been recognized, is superficial. We show that the biaxial data in all of the various swollen states including the neat (unswollen) state are satisfactorily described by an Ogden‐type strain energy function with a single set of parameters. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 721–728, 2010