Comparison of Ba(B1-xAlx)2O4 Single Crystals on their Diameters

Small diameter crystals of Ba(B_1-xAl_x)₂O₄ were grown by Floating zone pulling down method and Micro-pulling down method to be compared with large diameter crystals grown by Czochralski method. While the Czochralski grown crystal was opaque, the crystal transparency was actually improved with the decrease of crystal diameter, i.e., the decrease of constitutional supercooling. The reason was the increase of temperature gradient caused by down-sizing of the crystal diameter deduced by down-sizing of the growth furnace. The adequate diameter for transparent crystal was determined depending on the Al content.     

On the Potentiality of ‘Local Shaper’ Technique for Multicomponent Oxide Crystal Growth

The ‘Local Shaper’ Technique (LST) differs of Edge-defined Film-fed Growth (EFG) by the use of small die that specifies only a part of the potential crystal cross-section, while the whole one is obtained by means of translation. The applicability of LST for high-temperature multi-component oxide crystals, such as garnet and orthovanadate has been investigated. The operating regimes have been estimated in the comparison of corresponding EFG modes. Tubular and rod-like crystals of calcium-niobium-gallium garnet and yttrium vanadate were grown by LST successfully. The growth process model has been refined and discussed in the reference to crystal quality. Nevertheless the LST applicability for high-quality growth of multicomponent oxides has been marked as questionable.     

Copper-catalyzed [5+1] annulation of 2-ethynylanilines with an N,O-acetal leading to construction of quinoline derivatives

A novel copper-catalyzed [5 + 1] annulation of 2-ethynylanilines with an N,O-acetal, which functioned as a C1 part, leading to the preparation of quinoline derivatives with an ester substituent on the 2-position is described. A combination of CuBr(2) and trifluoroacetic acid (TFA) promoting [5 + 1] annulation of the 2-ethynylaniline with ethyl glyoxylate is also demonstrated.     

Liquid chromatographic method for the determination of sirolimus in blood using electrochemical detection

Therapeutic drug monitoring of sirolimus (rapamycin) is important for immunosuppressive therapy in solid organ transplantation. We have developed a simple and reliable method for determining blood concentrations of sirolimus using reversed-phase HPLC with electrochemical detection (ECD). The E(2) potential was set at +900 mV. The potential of guard cell was set at +950 mV and that of the E(1) cell at +400 mV. The method was linear for a concentration range of 1-50 ng/mL when 0.5 mL blood was used. The correlation coefficients of all standard curves were greater than or equal to 0.999. The limit of detection was 0.5 ng/mL. The inter-assay precision ranged from 3.22 to 7.48%, and the coefficient of variation (CV) for a quality control sample at 10 ng/mL was 7.48% with a bias of 8.4% from the target value. The intra-assay precision ranged from 0.72 to 3.71%, and the CV for a quality control sample at 10 ng/mL was 0.72% with a bias of 6.8% from the target value. In a solid organ transplant recipient, trough concentrations of sirolimus were well within the analytic range of the HPLC/ECD procedure. The method described here is suitable for management of sirolimus therapy in solid organ transplantation.     

Acoustic Imaging Frequency Dynamics of Ferroelectric Domains by Atomic Force Microscopy

We report the acoustic imaging frequency dynamics of ferroelectric domains by low-frequency acoustic probe microscopy based on the commercial atomic force microscopy. It is found that ferroelectric domain could be firstly visualized at lower frequency down to 0.5 kHz by AFM-based acoustic microscopy. The frequency-dependent acoustic signal revealed a strong acoustic response in the frequency range from 7kHz to 10 kHz, and reached maximum at 8.1 kHz. The acoustic contrast mechanism can be ascribed to the different elastic response of ferroelectric microstructures to local elastic stress fields, which is induced by the acoustic wave transmitting in the sample when the piezoelectric transducer is vibrating and exciting acoustic wave under ac electric fields due to normal piezoelectric effects.     

Spinorphin as an endogenous inhibitor of enkephalin-degrading enzymes: roles in pain and inflammation

It is possible that enkephalins are involved in the pain-modulating mechanism in the spinal cord. Enkephalins, however, are short-lived, being rapidly degraded by various endogenous enzymes. Many substances that inhibit enkephalin-degradation have been investigated and it has been reported that some inhibitors (e.g. kelatorphan and RB101) alone showed anti-nociceptive activity. We found an endogenous factor that modulated enkephalin-degrading activity and purified it from bovine spinal cord based on its inhibitory activity toward enkephalin-degrading enzymes. Structural analysis revealed the factor to be Leu-Val-Val-Tyr-Pro-Trp-Thr and it was named spinorphin. It has been found that spinorphin inhibited the activity toward various enkephalin-degrading enzymes from monkey brain, especially dipeptidyl peptidase III (DPPIII, Ki=5.1 x 10(-7) M). Recently we reported that this inhibitor significantly inhibited bradykinin (BK)-induced nociceptive flexor responses. Importantly, the mode of inhibition to BK-responses by spinorphin was different from the case with morphine. The morphine-induced blockade of BK-response was attenuated by pertussis toxin treatment, whereas that of spinorphin was not. We also have reported roles for spinorphin in inflammation. Spinorphin significantly inhibited the functions of polymorphonuclear neutrophils (PMNs) by suppressing the binding of fMLF to its receptor on PMNs. Further, this inhibitor suppressed the carrageenan-induced accumulation of PMN in mouse air pouches after intravenous administration. These results indicate that spinorphin may be an endogenous anti-inflammatory regulator. The possible role of spinorphin and its analog as regulators in pain and inflammation will be discussed.     

Piezoresponse imaging and local characterization of ferroelectric domains in Pb(Zn1/3Nb2/3)O3–7%PbTiO3 single crystals

Ferroelectric domain structures of (001)‐oriented Pb(Zn_1/3Nb_2/3)O₃–7%PbTiO₃ (PZN‐7%PT) single crystals were visualized and characterized by piezoresponse force microscopy (PFM). Locally regular domain configurations are found to be possibly related to the stable macroscopic properties in the PZN‐7%PT single crystals. Nanoscale piezoresponse hysteresis loops measured by PFM tip revealed no evidence of local domain switching behavior in the PZN‐7%PT single crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Unified treatment of positron annihilation and positronium formation

The effects of the positron (e(+)) annihilation in e(+) scattering by the H atom are included directly in the Hamiltonian as an absorption potential, and hence the finite lifetimes Gamma(ns) of positronium (Ps) in states ns are automatically taken account of. The Schr?dinger equation is solved using the hyperspherical close-coupling method. The annihilation and Ps formation are shown to be inseparable near the Ps(1s) threshold E(th); Ps formation constitutes just an indirect pathway to annihilation. The annihilation cross section, which would diverge near E(th) if Gamma(1s) were infinite, connects smoothly across E(th) to the cross section for Ps formation, which is meaningful only at energies well above E(th).