Hydrostatic pressure effects on superconducting transition of nanostructured niobium highly strained by high-pressure torsion

We study the effects of hydrostatic pressure (HP) compression on the superconducting transition of severely strained Nb samples, whose grain sizes are reduced to the submicrometer level. Engineered granularity by high-pressure torsion (HPT) treatment changes the strength of coupling between submicrometer-scale grains and introduces lattice strain. We attempt to utilize the initially accumulated shear strain in the starting material for increasing the superconducting transition temperature Tc under HP compression. The HP effects on non-strained Nb have already been investigated in the pressure regime over 100 GPa by Struzhkin et al. [Phys. Rev. Lett. 79, 4262 (1997)], and Tc reportedly exhibited an increase from 9.2 to 9.9 K at approximately 10 GPa. (1) Slightly strained Nb in the HPT treatment exhibits the increase in Tc under HP due to the strengthening of the intergrain coupling, so the pressure scale of the pressure response observed by Struzhkin et al. is reduced to approximately one-seventh at the maximum. (2) Prominently strained Nb in the HPT treatment exhibits the increase in Tc under HP due to a reduction in structural symmetry at the unit-cell level: In a Nb sample subjected to HPT (6 GPa, 10 revolutions), Tc exceeds 9.9 K at approximately 2 GPa. According to our first-principle calculations, the reduction in the structural symmetry affords an increase in the density of states at the Fermi energy, thereby yielding a prominent increase in Tc at low pressures

Hydrostatic Compression Effects on Fifth-Group Element Superconductors V, Nb, and Ta Subjected to High-Pressure Torsion

In fifth-group element superconductors V, Nb, and Ta, the increase in superconducting transition temperature (Tc) was attempted by using both high-pressure torsion (HPT) and additional hydrostatic pressure (HP) compression. The former brings about the grain refinement and strain accumulation in the unit-cell level. The additional compression for severely strained superconductors triggers strengthening intergrain-contact and/or structural deformation in the unit-cell level. The manner of the appearance of the above two effects depends on the kind of elements: First, in V, there is no prominent effect of HPT, comparing to the hydrostatic compression effects on its non-strained material. Next, in Ta, the effect of strengthening intergrain-contact appears at small hydrostatic compression, resulting in temporal increase in Tc. Finally, Nb exhibits prominent increase in Tc by both effects and, in particular, the structural deformation in the unit-cell level promotes the increase in Tc. Thus, the accumulation of residual strain in the level of starting material can be a promising work to manipulate Tc under HP compression

Proton Ejection and Uncoupling by Rhodamine 6G in Isolated Chloroplasts

書誌情報のみBibliographic data Onl

Physiological Studies on Photo-electric Response in Plant Tissues (Part 1) : Effects of the length of light and dark period upon photo-electric response in green leeves

書誌情報のみBibliographic data Onl

Spectral Energy Distribution of Artificial Illumination in Phytotron and Growth Cabinet

書誌情報のみBibliographic data Onl

Analysis of Titania Nanosheet Adsorption Behavior Using a Quartz Crystal Microbalance Sensor

We investigated the adsorption of albumin and fibronectin on a titania nanosheet- (TNS-) modified quartz crystal microbalance (QCM) sensor. A Ti QCM sensor was fabricated by reactive magnetron sputtering. A thin layer of Ti was deposited on the QCM sensor. This sensor was then alkali-modified by treatment with NaOH at room temperature to fabricate the titania nanosheets. Scanning probe microscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy were performed to investigate the surface topology and chemical components of each sensor. The TNS had a titanium oxide film exhibiting a nodular structure and a thickness of 13 nm on the QCM sensor. Furthermore, QCM measurements showed significantly greater amounts of albumin and fibronectin adsorbed on the TNS than on titanium. The NaOH treatment of titanium modified the sensor surface and improved the adsorption behaviors of proteins related to the initial adhesion of bone marrow cells. Therefore, we concluded that TNS improves the initial adhesion between the implant materials and the surrounding tissues

Action Spectrum of Light Pulse-Induced Membrane Depolarization in Pulvinar Motor Cells of Phaseolus

In addition to circadian changes in the membrane potential and leaf movement, light applied to the pulvinus causes changes in both the membrane potential and the pulvinar movement in Phaseolus vulgaris L. Even after a short pulse of light, a transient depolarization of the membrane occurs and leaf movement is observed. Decreases of turgor pressure of the motor cells are always preceded by the depolarization. The direction of the leaf movement can be explained by the decrease of turgor pressure in the motor cells on the irradiated side of the pulvinus. Using the Okazaki Large Spectrograph at the National Institute for Basic Biology, we determined the action spectrum of the membrane depolarization induced by light pulses (30 s) in motor cells of Phaseolus. The pulvinus was left exposed to air during measurement of the membrane potential with microelectrodes. The action spectrum obtained was in the range of 300 to 730 nm. It had the highest peak at 460 nm with lower peaks at 380 nm and 420 nm. Almost no sensitivity was observed at wavelengths shorter than 360 nm and longer than 520 nm. Red and far-red light had no effect on the depolarization of the motor cell. The features of the action spectrum are almost the same as those of the Blue-Type response in plants

ショクブツ カンキョウ チョウセツ ジッケン シセツ ノ ガイヨウ

書誌情報のみBibliographic data Onl