Mapping analyses of Fe-diffused mc-Si using M?ssbauer microscope and photoluminescence

Twenty CK chondrites collected in the Antarctica Continent were characterized by inductively-coupled plasma mass spectrometry (ICP-MS), prompt gamma ray analysis (PGA), instrumental neutron activation analysis (INAA), X-ray diffractometry (XRD) and ⁵⁷Fe-M?ssbauer spectroscopy. As a result of elemental analysis, it was revealed that 18.2~26.4 mass% of iron was included in the each chondrite. M?ssbauer spectrum of LEW86258, classified as a typical CK chondrite, was found to be composed of two paramagnetic doublets and two magnetic sextets. M?ssbauer spectra were assigned to the absorption due to forsterite (Mg_1.36Fe_0.64SiO₄) and magnetite (Fe₃O₄), as also confirmed by XRD. XRD study of LAP03834, reclassified from CK to R chondrite, revealed the presence of crystalline phase due to forsterite. These results indicate that LAP03834 and related chondrites, i.e., MET01149, LAP03923 and MAC02453, should be reclassified as R or LL chondrite.     

Mechanically strengthened new Hagi porcelain developed by controlling the chemical environment of iron

In order to enhance the mechanical strength of Hagi Porcelain (Hagiyaki), one of the oldest and famous potteries in Japan, new preparation condition was examined. Tempered Hagi porcelain, denominated as ‘Hagi Porcelain B’, was prepared with the Porcelain clay originating from Daido district, Yamaguchi Prefecture, Japan. Structural change of ‘Hagi Porcelain B’ was investigated by means of ⁵⁷Fe-Mössbauer spectroscopy, X-ray diffractometry (XRD) and three-point bending test. Mechanical strength of the ‘original Hagi Porcelain B’ was estimated to be 43.1 MPa by means of the three-point bending test, while much larger value of 104.5 MPa could be achieved when tempered by a chemical modification. Mössbauer spectrum of the ‘original Hagi porcelain B’ was composed of a paramagnetic doublet and a magnetic sextet due to Fe(III) of γ-Fe₂O₃(maghemite), while only one paramagnetic doublet due to to octahedral Fe(II)O₆ was observed for the ‘tempered Hagi Porcelain B’ with isomer shift and quadrupole splitting values of 1.13 and 2.15 mm s^?1, respectively. It is considered that the absence of magnetic phase causes an increase of the mechanical strength because the maghemite phase has a defect spinel structure. These results indicate that mechanical strength of the ‘Hagi porcelain B’ could be enhanced by controlling the sintering condition.     

Transfer hydrogenation of imines with carboxyl-tailed benzothiazoline as readily removable hydrogen donor

A benzothiazoline bearing 4-carboxyphenyl group at 2-position was developed as an efficient hydrogen donor for the transfer hydrogenation reaction. Introduction of the carboxyl group significantly facilitated the removal of the residual benzothiazoline and benzothiazole by washing with aqueous basic solution. The present approach provides a convenient and straightforward access to various amines with broad substrate scope and in good yields.     

Vinyl Polymerization. 436. Effect of Magnetic Field on Uncatalyzed Polymerization

The radical polymerization of vinyl monomers initiated with several kinds of hydrophilic macromolecule was carried out in a magnetic field. The magnetic field promoted the polymerization; the conversion of monomers and the molecular weight of the polymers obtained increased with increasing field strength in the range of 0–0.1 T. The dependence of the composition and tacticity of the mother polymer on the magnitude of the magnetic field was studied. Using graft or block copolymers, which consisted of hard and soft segments, the effect of a magnetic field was further investigated. The degree of hardness and tightness of the hydrophobic areas (reaction areas) formed by the mother polymer in the aqueous solution was found to affect the magnetic field effect on the uncatalyzed polymerization. The overall activation energy obtained in the magnetic field was almost equal to that obtained without a magnetic field.     

Concentration dependences of dielectric properties at 105 Hz and 106 Hz for aqueous solutions of hydroxypropyl cellulose

The concentration dependences of dielectric properties measured at 10⁵ Hz and 10⁶ Hz are reported for aqueous solutions of hydroxypropyl cellulose. Phase behaviour of the solutions was also observed with a polarizing optical microscope. For solutions with concentrations well above 40 wt %, polydomain textures, including the banded texture, were observed after a prehistory of deformation. No significant discontinuous changes in the dielectric constant, ε_r′, and loss factor, ε_r″, were found at the concentrations around the onset of the isotropic–cholesteric phase transition and in the biphasic region. In contrast, the steeper changes in ε_r′ and ε_r″ were found at the critical concentration for the fully developed cholesteric phase transition with the polydomain textures.     

Visco-elastic properties of reentrant nematic liquid crystalline mixtures

The visco-elastic properties for binary mixtures of 4-n -hexyloxy-4′-cyanobiphenyl (6OCB) and 4-n-octyloxy-4′-cyanobiphenyl (8OCB) are investigated in detail by a light scattering technique. The mixtures exhibit a reentrant nematic (RN) phase between the smectic A (SmA) and crystal phases in the range 22.0–29.5 wt % of 6OCB. The viscosity and the elastic constant increase with cooling in both the nematic and reentrant nematic phases. It is also found that the mixtures exhibit anomalously large values of viscosity and elastic constant near the phase transition, i.e. a pretransitional phenomenon can be observed. The activation energy for viscosity is smaller in the RN phase than in the ordinary nematic phase appearing at higher temperatures, while the normalized elastic constant (defined as the ratio of the elastic constant to the square of the dielectric anisotropy) is larger. Moreover, the visco-elastic behaviour depends on the specific time during which the sample has been kept in the SmA phase. These results confirm that the SmA phase has a strong influence on the formation of molecular aggregates, which plays an important role in the reentrant phenomenon of these systems.     

Control of the Orientation and Photoinduced Phase Transitions of Macrocyclic Azobenzene

Photoinduced phase transitions caused by photochromic reactions bring about a change in the state of matter at constant temperature. Herein, we report the photoinduced phase transitions of crystals of a photoresponsive macrocyclic compound bearing two azobenzene groups ( 1 ) at room temperature on irradiation with UV (365 nm) and visible (436 nm) light. The trans/trans isomer undergoes photoinduced phase transitions (crystal–isotropic phase–crystal) on UV light irradiation. The photochemically generated crystal exhibited reversible phase transitions between the crystal and the mesophase on UV and visible light irradiation. The molecular order of the randomly oriented crystals could be increased by irradiating with linearly polarized visible light, and the value of the order parameter was determined to be ?0.84. Heating enhances the thermal cis‐to‐trans isomerization and subsequent cooling returned crystals of the trans/trans isomer.     

57Fe-Mössbauer study of electrically conductive alkaline iron vanadate glasses

A relationship between local structure, thermal stability and electrical conductivity (σ) of xR₂O·10Fe₂O₃·(90 ? x)V₂O₅ glasses (abbreviated as xRFV glasses, where R = Li, Na, K; x = 20 and 40 in mol %) was investigated by ⁵⁷Fe-Mössbauer spectroscopy, X-ray diffractometry, differential thermal analysis (DTA) and DC two- and four-probe method. From DTA study, thermal stability of 20RFV glasses is lower than that of 40RFV glasses by evaluating Hruby parameter (K _gl). Constant activation energy for crystallization (E _a) of 2.5 eV obtained from both 20RFV and 40RFV glasses indicate that the crystallization proceeds with the cleavage of Fe–O bond having the energy of 2.6 eV. Isochronally annealed 20RFV glass at 400–450 °C resulted in the increase in electrical conductivity (σ) from the order of 10^?3 to 10^?1 S cm^?1, whereas slight decrease in σ was observed for 20RFV glass annealed above 460 °C. A paramagnetic doublet with an identical isomer shift (δ) of 0.39 mm s^?1 was observed in the ⁵⁷Fe-Mössbauer spectra of 20RFV glass after isothermal annealing conducted at 400–450 °C for 100 min, which caused a decrease of quadruple splitting (Δ) from 0.67 to 0.52 mm s^?1 for 20LiFV glass and from 0.66 to 0.53 mm s^?1 for 20NaFV glass. On the other hand, three paramagnetic doublets with δ and Δ of 0.40 and 0.25, 0.38 and 0.60, and 0.31 and 1.11 mm s^?1 respectively were observed for 20RFV glass annealed at 460–550 °C, reflecting precipitation of semiconducting FeVO₄ phase having σ of 6.0 × 10^?7 S cm^?1. It can be concluded that isochronal annealing of 20RFV glass below 450 °C resulted in increase in σ due to the structural relaxation, while annealing above 500 °C resulted in the decrease of σ due to the precipitation of FeVO₄ phase.     

Chiral Phosphoric‐Acid‐Catalyzed Transfer Hydrogenation of Ethyl Ketimine Derivatives by Using Benzothiazoline

Chiral phosphoric acid catalyzed transfer hydrogenation of ketimines derived from propiophenone derivatives and reductive amination of alkyl ethyl ketone derivatives were extensively examined in the presence of two representative hydrogen donors. The excellent enantioselective transfer hydrogenation was achieved by use of benzothiazoline as a hydrogen donor. The theoretical studies elucidated that the unsymmetrical structure of benzothiazoline plays an important role in high enantioselective hydrogenation.     

Effect of Interventions for Improving Lumbar Motor Control on Low Back Pain in Sedentary Office Workers: A Randomized Controlled Trials

Objective: To clarify the effect of intervention with dynamic motor control exercise (DMCE) for the lumbar region on low back pain in sedentary office workers (SOWs). Methods: The participants comprised 32 SOWs with low back pain who were randomly categorized into two groups: the DMCE group and the normal trunk exercise (NTE) group. Both groups performed each exercise for three days per week for 8 weeks. The primary endpoints were evaluated for the lumbar and hip flexion angles during trunk forward bending, effect of low back pain on activities of daily living (using the Oswestry Disability Index), and intensity of low back pain (using the Visual Analog Scale) pre- and post-intervention. The extent of changes was calculated by subtracting the pre-intervention value from the post-intervention value and was compared between the two groups using an unpaired t-test. Results: The extent of changes in the lumbar flexion and hip flexion angles at 10° of trunk forward bending were significantly greater in the DMCE group than in the NTE group, and no significant differences were noted between the two groups at other angles of trunk forward bending. The extent of changes in the Oswestry Disability Index and the Visual Analog Scale scores were significantly greater in the DMCE group than in the NTE group. Conclusion: DMCE is effective in improving motor control in the lumbar region and hip joints, thereby ameliorating low back pain in SOWs.