Rare-earth silicate with an apatite structure is a new type of oxide ion conductor, the electrical conductivity of which is higher at relatively low temperatures than that of stabilized zirconia. ...Single crystals are indispensable in order to reveal the intrinsic bulk properties such as anisotropy of electrical conductivity. This paper reviews our recent research work on single crystals growth by the floating zone method and electrical properties of this material, including reinvestigation of phase relations in Nd
2O
3–SiO
2 system and structure refinement using neutron diffraction. A possible mechanism for the oxide ion conduction is proposed based on the existence of cation vacancies.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
It has been known that giant DNA shows structural transitions in aqueous solutions under the existence of counterions and other polymers. However, the mechanism of these transitions has not been ...fully understood. In this study, we directly observed structures of probed (dye-labeled), dilute DNA chains in unprobed DNA/polyethylene glycol (PEG)/monovalent salt (NaCl) aqueous solutions with fluorescent microscopy to examine this mechanism. Specifically, we varied the PEG molecular weight and salt concentration to investigate the effect of competition between the depletion and electrostatic interactions on the coil-globule transition and the aggregate formation. It was found that the globules coexist with the aggregates when the unprobed DNA chains have a concentration higher than their overlap concentration. We discuss the stability of the observed structures on the basis of a free energy model incorporating the attractive depletion energy, the repulsive electrostatic energy, and the chain bending energy. This model suggested that both of the globules and aggregates are more stable than the random coil at high salt concentrations/under existence of PEG and the transition occurs when the depletion interaction overwhelms the electrostatic interaction. However, the coexistence of the globule and aggregate was not deduced from the thermodynamic model, suggesting a nonequilibrium aspect of the DNA solution and metastabilities of these structures. Thus, the population ratio of globules and aggregates was also analyzed on the basis of a kinetic model. The analysis suggested that the depletion interaction dominates this ratio, rationalizing the coexistence of globules and aggregates.
Uniaxial extensional flow behavior was measured for the high-melt-strength polypropylene using a Meissner-type rheometer under transient extensional flow with constant tensile strain rate. The ...equibiaxial extensional flow behavior of the high-melt-strength polypropylene was measured via the lubricated squeezing flow method under constant strain rate. The high-melt-strength polypropylene consists of polypropylene (PP) as a main component and high-molecular-weight polyethylene (PE) component as a long relaxation time component (see part 1). This system is generally believed to be an immiscible system, at least under the quiescent state. Nevertheless, in part 1, we have found that the high-melt-strength PP with very high-molecular-weight PE shows distinctly different shear flow behaviors from conventional PP, e.g., high elasticity and two-step viscosity at low shear rates and strong and weak strain-dependent nonlinear damping functions characterizing fast and slow relaxation processes. In this study, the transient uniaxial viscosity of the high-melt-strength PP melts first increased gradually with time, following the linear viscoelastic rule in which the uniaxial extensional viscosity is 3 times the shear viscosity development. Beyond a certain critical strain, the uniaxial extensional viscosity showed rapid increase, which was referred to as strain hardening. Furthermore, the transient biaxial extensional viscosity showed also the strain hardening behavior over a critical strain. These prominent behaviors are unexpected for conventional PP. The nonlinear upturn behavior was discussed from a high-molecular-weight chain stretching point of view via molecular constitutive equations given by Osaki et al. for bimodal polymer blends.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Acicular crystals were grown in gallium oxynitride powder prepared by ammonia nitridation of amorphous gallium oxide precursors containing less than 5 at% of either Ni or Co,
via
the citrate route. ...The crystals were several tens of nanometres wide, several micrometres long, and grown in the temperature range 750 to 850 °C in a flow of ammonia of less than 200 mL min
−1
. The crystal structure of the gallium oxynitride was a highly disordered 2H wurtzite-type with some 3C zinc blende-type stacking faults. The crystals grew in their basal plane changing their aspect ratio with the supplying method of small amounts of Ni or Co and an amount of residual carbon. The acicular crystals were grown by the catalytic behavior of Ni or Co to enhance one-dimensional growth in the hexagonal
c
-plane.
Gallium oxynitride nanofibers were grown one-dimensionally in the
c
-plane of the wurzite-type lattice
via
a non-VLS mechanism with nickel or cobalt impurity.
Single crystals of Nd9.33(SiO4)6O2 and Sr2Nd8(SiO4)6O2 oxide ion conductors with the oxyapatite structure were grown without any macroscopic defect by the floating zone method. The oxide ion ...conductivity of the Sr2Nd8(SiO4)6O2 single crystal varied with the distance from its seed crystal along the growth direction, because of its changing deficiency in Sr content. Its stoichiometric portion had a lower electrical conductivity by about five orders of magnitude at 600 deg C than the value for Nd9.33(SiO4)6O2 single crystal. Structural refinement of neutron diffraction data for powdered Nd9.33(SiO4)6O2 single crystal showed that the previous structure analysis was misleading. Cation vacancies were present only at 4f site and its channel oxygen site was fully occupied in space group of P63/m. The oxygen had an anisotropic displacement along the channel in the refined oxyapatite structure.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Optical microscopic observation of laser drawn Fe lines on a FeN/AlN thin film.
Display omitted
▶ Microstructures were formed in iron nitride thin film for left-handed metamaterials. ▶ Iron granules ...dispersed thin film was obtained by thermal annealing of Fe
0.5Al
0.5N film. ▶ In Fe
0.7Al
0.3N film, iron metal lines were drawn by the laser direct writing.
The thermal metastability of iron nitride was exploited to fabricate thin-film microstructures applicable to left-handed metamaterials. A granular thin film containing dispersed iron particles was prepared by post-annealing an rf-sputter-deposited Fe
0.5Al
0.5N thin film with a wurtzite-type structure in a nitrogen atmosphere at 450
°C. The obtained samples showed magnetic resonance in the microwave region. Laser direct writing was also applied in a nitrogen atmosphere to an rf-sputter-deposited Fe
0.7Al
0.3N thin film. 200
μm-wide, 300
Ω
cm iron metal lines were drawn in a host nitride film of approximately 2
kΩ
cm. Combining and optimizing the above negative permeability and permittivity values should provide left-handed materials with a negative refractive index.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Incubation of human liver microsomes with diclofenac in the presence of NADPH resulted in a decrease in testosterone 6 beta-hydroxylation activity. The decrease in the activity followed time- and ...concentration-dependent kinetics, required oxidative metabolism, and was resistant to reduced glutathione, suggesting that diclofenac causes a mechanism-based inactivation of cytochrome p450 (p450) 3A4 (CYP3A4). The inactivation was reproduced by using microsomes from B-lymphoblastoid cell lines expressing CYP3A4 instead of human liver microsomes. No other monooxygenase activities measured as indexes of p450 enzymes; CYP2C8, CYP2C9, or CYP2C19 was inactivated by the same incubation procedure. Quinidine, a stimulant of CYP3A4-mediated diclofenac 5-hydroxylation, did not affect the inactivation of CYP3A4 assessed by testosterone 6 beta-hydroxylation activity but accelerated the inactivation assessed by diazepam 3-hydroxylation activity. These results supported the idea that diclofenac 5-hydroxylation is involved in the inactivation of CYP3A4 and described for the first time a stimulation of mechanism-based inactivation attributable to CYP3A4 heterotropic cooperativity. Preincubation of human liver microsomes with 5-hydroxydiclofenac instead of diclofenac did not cause the inactivation of CYP3A4, suggesting that 5-hydroxydiclofenac is not a precursor of a postulated reactive metabolite that inactivates CYP3A4, and thus 5-hydroxylation step is critical to inactivation of CYP3A4.
FTY720, a novel immunosuppressant, sequesters circulating mature lymphocytes, especially T cells, within lymph nodes and Peyer’s patches by accelerating lymphocyte homing, and thereby causes ...lymphocyte depletion in the blood. The FTY720‐induced acceleration of lymphocyte homing appears to be mediated by lymphocyte homing receptors including CD62L, CD49d/β7, and CD11a/CD18. In this study, expressions of CD62L, CD49d and CD11a on T cells in the peripheral blood, lymph nodes and Peyer’s patches were analysed by flow cytometry in rats given FTY720 (1 mg/kg) orally. FTY720 markedly decreased the number of peripheral blood T cells, while not affecting CD62L, CD49d and CD11a expressions at 1–3 hr after administration. In contrast, both the frequency of CD62L‐positive T cells and intensity of CD62L expression on T cells were increased in Peyer’s patches but not lymph nodes at 3 hr after administration of FTY720. CD49d and CD11a expressions on T cells were unaffected by FTY720 in both Peyer’s patches and lymph nodes at the same point in time. On the other hand, analysis of lymphocyte homing with calcein‐labelled lymphocytes and anti‐CD62L monoclonal antibody (mAb) confirmed that FTY720 predominantly increased CD62L‐dependent lymphocyte homing to Peyer’s patches. These findings indicate that FTY720 increases the frequency of CD62L‐positive T cells by accelerating CD62L‐predominant homing in Peyer’s patches.
Full text
Available for:
BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
