Analysis of glycosyl bond cleavage and related isotope effects in collision-induced dissociation quadrupole-time-of-flight mass spectrometry of isomeric trehaloses

The configuration isomers alpha,alpha-, alpha,beta-, and beta,beta-trehalose are distinguishable by a relative ion abundance analysis using collision-induced dissociation MS/MS measurements in electrospray ionization quadrupole-time-of-flight mass spectrometry. The relative abundance of the Y-type fragment ion of alpha,alpha-trehalose is the highest and that of beta,beta-trehalose is the lowest, indicating that alpha-glycosyl bonds cleave more easily than beta-glycosyl bonds. The relative ion abundance depends on both the alpha- and beta-glycosyl linkage type and the number of alpha-glycosyl bonds. The reaction path of glycosyl bond cleavage is calculated computationally using the molecular orbital method in the form of Hartree-Fock theory in conjunction with the 6-31G(d) basis set. The results are consistent with the experimental data. Isotope effects on the fragmentation of the glycosyl bonds are detected in the experiments of the H2O/D2O solvent systems. Furthermore, the isotope effect regarding beta,beta-trehalose is larger than those of alpha,alpha- and alpha,beta-trehalose, indicating that the isotope effect on the beta-glycosyl bond cleavage is larger than that on the alpha-glycosyl bond cleavage. The thermal energy increase in trehalose-d8 molecules over the corresponding trehalose molecules is calculated from the vibrational modes.     

Thermal degradation characteristics of oil‐filled cable joint with extremely degraded tan δ oil

Much of oil‐filled (OF) cable has been used for a long time as 66‐ to 500‐kV extrahigh‐voltage cable. Sometimes we can see extremely degraded tan δ oil (several tens of percent of tan δ, for example) in joint boxes, etc. The values of tan δ calculated by a simple combination model of paper/oil show that the oil‐impregnated paper with such a high tan δ oil likewise has an extremely high tan δ, which must result in thermal breakdown. However, such an event has not taken place up to the present in actually operated transmission lines. This fact suggests that some mechanism for the suppression of tan δ has acted in the paper insulation impregnated with degraded tan δ oil. Therefore, we investigated in detail the tan δ characteristics of paper impregnated with extremely high tan δ oil. In addition, based on the investigation results, we developed a method for simulation of heat generation by dielectric loss in an OF cable joint (which has degraded tan δ oil). © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(1): 1–10, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21184     

A New Hybrid Phosphine Ligand for Palladium‐Catalyzed Amination of Aryl Halides

A new hybrid phosphine was designed. The phosphine combines two common structural characteristics found among the effective phosphine ligands reported recently, namely, three tert‐alkyl substituents binding to the phosphorus and an aryl group at an appropriate position. A hybrid phospine/palladium system is versatile and effective for the coupling reaction of various aryl halides with primary and secondary amines including carbazole.     

Effect of texture on oxidation resistance of Ti3AlC2

Oxidation resistance of textured Ti₃AlC₂ ceramics was measured in the temperature range 1273–1573?K. It was found that the oxidation was markedly anisotropic and the samples exhibited a better oxidation resistance when tested along a direction transverse to the c-axis. This behavior was attributed to the rapid diffusion of Al within its basal planes to form a passivating Al₂O₃ scale and it respected Ellingham diagrams. The scales formed had different compositions depending on the testing direction; this response was clearly resulting from the crystallographic orientation. Even at 1473?K after 20?h exposure, the samples tested in a direction transverse to the c-axis showed a reduced weight gain which was 45 times lower than one seen on a basal plane.     

Development of measuring system for radial non-repetitive run-out (NRRO) and perception about present state of angular contact ball bearing for machine tools

This paper deals with the non-repetitive run-out (NRRO) of an angular contact ball bearing for machine tools. First, a measuring system for the rotational accuracy of the bearing was developed. Then, the following results were obtained using the developed measuring system.

(1)

The NRRO of ball cage rotation increased with rotational speed.

(2)

The influence of form errors in the inner and outer rings on NRRO was small.

(3)

The influences of form errors in the balls of the bearing and the diameter difference of balls on NRRO were significant.

     

Fabrication of lead-free piezoelectric (Bi<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>)TiO<Subscript>3</Subscript>–BaTiO<Subscript>3</Subscript> ceramics using electrophoretic deposition

Electrophoretic deposition (EPD) process has certain advantages such as it can be applied for a mass production and also can be combined with magnetic crystal alignment technique. In this work, we prepared lead-free 85(Bi_0.5Na_0.5)TiO₃–15BaTiO₃ (85BNT–15BT) piezoelectric ceramics by conventional uniaxial pressing and EPD process. Various conditions were optimized such as suspension media, applied electrical field, and deposition time in order to yield dense green ceramics of 85BNT–15BT composition using EPD process. 85BNT–15BT ceramics prepared using EPD process revealed the Curie temperature of about 250 °C, coercive field of about 30 kV/cm, and piezoelectric constant (d ₃₃) of 75 pC/N. The EPD-processed samples exhibited structural and electrical properties similar to that of the conventionally processed one suggesting the successful fabrication of 85BNT–15BT piezoelectric ceramics by EPD method without composition deviation. This study lays a foundation on the fabrication of Bi-based lead-free piezoelectric ceramics by an alternative route other than the conventionally practiced solid-state reaction method maintaining the similar chemical composition, moreover, leaving a large space to explore more in the future.     

Electrodeposition and growth mechanism of preferentially orientated nanotwinned Cu on silicon wafer substrate

Homogeneous columnar Cu film with fully embedded nanotwins was successfully fabricated on Ti/Cu seed layer on silicon wafer. The nanotwins with thickness of tens of nanometers are generally parallel to the silicon surface, showing a strong (111) preferred orientation. The acid concentration was found to be important in influencing the formation of nanoscale twins. By adjusting the acid concentration, the nanotwins can be induced from the top columnar grain to middle columnar grain and reach the bottom equiaxed grain, and a microstructural transformation model was given. A theory focusing on the cathode overpotential was proposed to reveal the effect of acid concentration on the growth mechanism of nanoscale twins. An appropriate adsorption proportion of hydrogen on cathode (acid concentration 17 ml L^?1) could increase the overpotential which supplies adequate nucleation energy for nanoscale twins formation.     

Facilitated permeation of myoglobin through porous membranes: Different permeation behavior through membranes of polyoxyethylene- and dextran-conjugated polyamides prepared by quasi-living polymerization of a bicyclic lactam

In the ultrafiltration test of a myoglobin solution through porous membranes of the ABA-type block copolymers composed of polyamide as outer segments and polyoxyethylene (M_n = 1.9–2.0 × 10⁴) as an inner segment, in which the values of weight fraction of the polyamide segments (W) were 0.90, 0.84, 0.82, 0.81, and 0.73, the concentration of the permeate was found to be much higher than that in feed under the pressure difference of 1–2 kg/cm². Such singularly facilitated permeation was observed also in the test through the dense membranes of the polyamide–polyoxyethylene block copolymer with W of 0.81 and 0.73. On the other hand, neither porous nor dense membranes of the graft copolymer (W = 0.83) having a dextran stock (M_n = 1.8 × 10⁴) and 2.6 pieces of polyamide branches showed similar facilitated permeation, although dextran was soluble in water as well as polyoxyethylene. The apparent interaction of myoglobin with dextran may be stronger than that with polyoxyethylene. © 1994 John Wiley & Sons, Inc.     

Preparation and Electric Properties of Dense Nanocrystalline Zinc Oxide Ceramics

This communication reports on the preparation and electric properties of dense nanocrystalline ZnO ceramics. By spark plasma sintering, nanocrystalline (∼100 nm) ZnO ceramics with a high density of 98.5% were obtained at a very low temperature of 550°C. Electric property measurement revealed a novel conduction nonlinearity in the sample sintered at 500°C. This phenomenon is due to the nanometerization of ZnO crystal and the grain boundary layer with an amorphous interfacial layer.     

Effect of the preparation condition on the properties of titania-silica derived from tetraisopropyl titanate(IV) and tetraethyl orthosilicate

Titania-silica mixed oxide was prepared by hydrolyzing tetraethyl orthosilicate and tetraisopropyl titanate(IV) with a mixture of ethanol and 0.01 N aqueous acetic acid. Surface Ti content, BET surface area, and the number of acid sites increased with an increase in 0.01 N aqueous acetic acid. Thus hydrolysis of both alkoxides occurred simultaneously with a large amount of the acetic acid solution, and there was extensive interaction between TiO₂ and SiO₂ phases. With small amount of 0.01 N aqueous acetic acid, however, titanium hydroxide was first formed and, then, it was covered with the silica phase produced in a later stage of the hydrolysis. Increase in the acetic acid solution also led to the formation of a large amount of tetrahedral Ti species, which were active for the epoxidation of oct-1-ene usingt-butyl hydroperoxide as an oxidant.