Lattice instability in the normal state of La2−x Sr x CuO4

Novel softening has been found in the transverse elastic constant (C ₁₁–C ₁₂)/2 below 50 K in single-crystalline La_1.86Sr_0.14CuO₄ (LSCO) by high-precision ultrasonic measurements in magnetic fieldsH along thec axis. With decreasing temperature, this lattice softening persists down to the superconducting transition temperatureT _c(H), which is reduced to 14 K by applying fields up to 14 T. BelowT _c(H) the softening turns to rapid hardening. This behavior indicates the presence of lattice instability of the orthorhombic (Bmab) structure in the normal state of LSCO, which disappears in the superconducting state. This is evidence for the intimate interplay between high-T _c superconductivity and the lattice instability in LSCO.     

Dopamine D3 and D4 receptor antagonists: synthesis and structure--activity relationships of (S)-(+)-N-(1-Benzyl-3-pyrrolidinyl)-5-chloro-4- [(cyclopropylcarbonyl) amino]-2-methoxybenzamide (YM-43611) and related compounds

In this study, we synthesized a series of (S)-N-(3-pyrrolidinyl)benzamide derivatives, 1, 2a-d, 5a-1, and 7, and their enantiomers, (R)-1 and (R)-5c-e, and evaluated their binding affinity for cloned dopamine D2, D3, and D4 receptors and their inhibitory activity against apomorphine-induced climbing behavior in mice. The results indicate that D2, D3, and D4 receptors have different bulk tolerance (D4 > D3 > D2) for the substituent of the 4-amino group (R1) on the benzamide nuclei and that cyclopropyl-, cyclobutyl-, and cyclopentylcarbonyl groups likely possess adequate bulkiness with respect to D3 and D4 affinity and selectivity over D2 receptors in this series. The results also suggested that the N-substituent (R2) on the pyrrolidin-3-yl group performs an important role in expressing affinity for D2, D3, and D4 receptors and selectivity among the respective subtypes. One of the compounds, (S)-(+)-N-(1-benzyl-3-pyrrolidinyl)-5-chloro-4-[(cyclopropylcarbonyl+ ++) amino]-2-methoxybenzamide (5c) (YM-43611), showed high affinity for D3 and D4 receptors (Ki values of 21 and 2.1 nM, respectively) with 110-fold D4 selectivity and 10-fold D3 preference over D2 receptors and weak or negligible affinity for representative neurotransmitter receptors. Compound 5c displayed potent antipsychotic activity in inhibiting apomorphine-induced climbing behavior in mice (ED50 value, 0.32 mg/kg sc).     

The outcome of patients with mediastinal tumors detected by mass screening versus the outcome of those initially presentating with symptoms

Forty seven patients with mediastinal tumors, who were diagnosed between 1976 and 1996 at Tsukuba University Hospital, were evaluated according to the circumstances surrounding their initial consultations. The outcome of 19 patients (40.4%) whose tumors were detected by mass screening was compared with the outcome of 20 patients (42.6%) whose tumors were detected after presenting with symptoms. In the mass screening group, only 21% of the patients had a malignant neoplasm, whereas 75% of patients in the symptomatic group had a malignant neoplasm (p = 0.0008). Patients in the screening group had a shorter hospital stay than those in the symptomatic group (60.5 vs. 118. 1days; p = 0.0022). In patients with thymomas, in the mass screening all patients group were at stage I or II. Only 20% of the lesions in symptomatic patients were at stage I or II (p < 0.0001). Based on the results of this study, we believe that the early detection of mediastinal tumors via mass screening might have clinical significance.     

Oscillatory convection in a dilute3He-superfluid4He solution

Convective instabilities in a rectangular, unity-aspect-ratio Rayleigh-Bénard cell with a solution of 1.46%³He in superfluid⁴He have been studied in the temperature range 0.70–1.05 K, with a corresponding Prandtl number range of 0.045<<0.15. The onset of stationary convection is much like that in a classical, one-component fluid. The oscillatory instability is studied by using an extremely sensitive local temperature probe. It is found that the total heat transport efficiency is suppressed by the oscillations in the entire range of Prandtl number we have studied. The local temperature probe indicates a striking difference in the oscillatory amplitude when the sense of rotation of the convective rolls is reversed. The magnitude of the convective velocity is deduced from both the initial slope of the Nusselt number near the onset of the stationary convection and the frequency of the oscillations. Determinations of the temperature dependence of the convective velocity using these two methods agree very well. The observed behavior of the oscillatory frequency and onset condition supports the theory of oscillatory convection for a classical, low-Prandtl-number, one-component fluid.     

Pressure effects of resistivity along thec axis in La2−x Sr x CuO4

Out-of-plane resistivity p_c(T) of optimally-doped high-T_c superconductor La_2–xSr_xCuO₄ has been investigated under hydrostatic pressure up to 8GPa. We found a drastic decrease in _c which reaches 50% at 8GPa. The large change of _c is understood as due to a small variation of the lattice parameter c. In comparison with a change of p_c(T) estimated from a change of c due to thermal contraction, we conclude that the well known temperature-linear dependence of _c is apparent metallic one; essentially _c is nonmetallic over the whole temperature range, and can be described in terms of tunneling or quantum hopping conduction between CuO₂ layers. Such tunneling conduction is enhanced by the scattering in the CuO₂ plane at the oxygen defects which affect the in-plane resistivity only very weakly.     

Estimation of conductivity and permittivity of water trees in PEfrom space charge distribution measurements

Using an improved pulsed electroacoustic system which is capable of measuring space charge distribution at minimum intervals of 25 μs, the charge distribution inside water-treed polyethylene (PE) was examined. From the results, the frequency dependencies of conductivity and permittivity were examined for water trees grown in PE. The conductivity of the water-treed region is found to be >10¹⁰× higher than that of non-treed regions, while the permittivity increase is only slight     

High‐sensitivity PEA system with dual‐polarity pulse generator

The pulsed electroacoustic (PEA) method has been widely used to observe space charge distributions in various solid dielectric materials. The sensitivity of the conventional PEA system is around 1C/m³. When the charge density is less than 1C/m³, however, it is difficult to obtain an accurate result because the signal due to the Maxwell stress becomes comparable with the signal to be measured. The Maxwell stress is generated by applying the pulsed electric field to the dielectrics, and independent from the existence of either induced charges by DC bias voltage or internal charges. In order to eliminate the influence of the Maxwell stress, we have developed a new PEA system with a dual‐polarity pulse generator. The system allows measurement space at a charge density of around 0.03C/m³. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 1– 7, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20496     

Punching of small hole of die-quenched steel sheets using local resistance heating

A punching process of a small hole in a die-quenched steel sheet having high strength using local resistance heating of a shearing zone was developed to decrease the punching load. Uniform temperature in the circular shearing zone of the hole was obtained by optimising heating conditions for a pair of rectangular electrodes. The punch load and the burnished surface area for the heating at 500 °C were about 1/3 smaller and 2 times larger than those for the cold punching, respectively, and the occurrence of delayed fracture around the punched hole was prevented by the heating above 500 °C.     

Superconducting Properties of the 3-K Phase of Sr2RuO4 near Hc2

The superconducting transition temperature, T _c , of the impurity-free, intrinsic Sr₂RuO₄ is as high as 1.50 K. However, we recently showed that T _c is remarkably increased up to 3 K in the Sr₂RuO₄–Ru eutectic system, in which plate-like microdomains of Ru metal are embedded in the primary-phase Sr₂RuO₄. The phase diagram of the anisotropic upper critical field of the 3-K phase indicates that H _c2 for the field parallel to the RuO₂ plane is strongly suppressed at low temperatures. We argue that the reorientation of the Cooper-pair spin direction near the Sr₂RuO₄–Ru interface may be responsible for this suppression. In addition, we observed unusual hysteresis in the out-of-plane resistivity, _c , at low temperatures and near H _c2, only when the field was applied parallel to the RuO₂ plane.     

Aspects of CO2 laser engraving of printing cylinders

Results of the experimental and theoretical investigations of CO(2) laser-engraved cylinders are presented. The processed surfaces of test samples are examined by a phase-stepping laser interferometer, digital microscope, and computer-controlled profilometer. Fourier analysis is made on the patterns parallel to the axis of the laser-scribed test ceramic cylinders. The problem of the visually observed banding is discussed.