Thermal resistance in Speer carbon resistors below 1 K

Temperature dependences of Speer carbon resistors between 30 mK and 4.2 K have been measured. The applied electric power at which the resistance decreases by 1% was measured accurately over the same temperature range. From these data, discussions of the thermal resistance of the resistors are made in detail. Some techniques to measure carbon resistance below 1 K, including the method to remove heat leaks, are described.     

Active RC networks using a parallel T

A method of independent control over the positions of the poles and zeros of an active RC network is described, Secondorder transfer functions can be realised by using these circuits. The adjustments of their characteristics after the construction are very easy. A simple experiment shows good agreement with the theory.     

Efficient selection of hybrids by protoplast fusion using drug resistance markers and reporter genes in Saccharomyces cerevisiae

We have developed a selection system for hybrids by protoplast fusion using dominant selective drug resistance markers, Tn601(903) against geneticin and AUR1-C against aureobasidin A, and reporter genes, ADH1p-PHO5-ADH1t and CLN2p-CYC1-lacZ, in Saccharomyces cerevisiae. To examine the effectiveness of this system, plasmids with each marker and reporter gene were introduced into auxotrophic sake yeasts. From the resulting transformants, eight colonies were screened by protoplast fusion in combination with the drug resistance markers and the reporter genes. Among them, seven strains were judged as hybrids between parental strains by analysis of growth on a minimal medium. This selection system was applied to wine yeasts having no genetic markers. Six strains were regarded as hybrids between parental strains by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis of the MET2 gene and by karyotype analysis using a contour-clamped homogeneous electric field (CHEF). We propose that the plotoplast fusion using dominant selective geneticin- and aureobasidin A-resistance markers and reporter genes is useful for the selection of hybrids from wine yeasts, which are homothallic and have low sporulation ability.     

Construction of 144, 565 keV and 5.0 MeV monoenergetic neutron calibration fields at JAERI

Monoenergetic neutron calibration fields of 144, 565 keV and 5.0 MeV have been developed at the Facility of Radiation Standards of JAERI using a 4 MV Pelletron accelerator. The 7Li(p,n)7Be and 2H(d,n)3He reactions are employed for neutron production. The neutron energy was measured by the time-of-flight method with a liquid scintillation detector and calculated with the MCNP-ANT code. A long counter is employed as a neutron monitor because of the flat response. The monitor is set up where the influence of inscattered neutrons from devices and their supporting materials at a calibration point is as small as possible. The calibration coefficients from the monitor counts to the neutron fluence at a calibration point were obtained from the reference fluence measured with the transfer instrument of the primary standard laboratory (AIST), a 24.13 cm phi Bonner sphere counter. The traceability of the fields to AIST was established through the calibration.     

Dynamic behavior of bubble domains at low drive field

Dynamic properties of bubble domains at low drive pulse field are examined by the bubble transport method. Important findings are as follows. 1) The bubble does not move unless the pulse duration exceeds a critical value which depends on the pulse amplitude. 2) A minimum pulse amplitude is also required for the bubble translation which depends on the pulse duration. 3) As the pulse duration goes to infinity, the minimum drive field approaches a constant value which is different from the dynamic coercivity. 4) As soon as the pulse duration exceeds the critical value, the bubble is displaced discontinuously by a finite distance independent of the drive field. All of these properties are adequately explained by a simple phenomenological theory, in which the domain wall is assumed to be connected by springs to pinning sites until the wall is displaced by a finite distance.     

Synthesis of TiO2/CdS nanocomposite via TiO2 coating on CdS nanoparticles by compartmentalized hydrolysis of Ti alkoxide

Hydrolysis of Ti alkoxide in the presence of inverse micelles containing CdS nanoparticles in their hydrophilic interior results in formation of TiO₂/CdS nanocomposites in which the CdS nanoparticles are embedded in a TiO₂ matrix with a thickness of 10 nm at the surface of the particles. The primary hydroxyl groups introduced by 2-mercaptoethanol as a capping agent used for preparation of the CdS nanoparticles are considered to play an important role for successful adhesion and growth of the TiO₂ layer on the CdS surfaces. TEM observation strongly supports formation of semiconductor-in-semiconductor heteronanostructure by compartmentalized hydrolysis of Ti alkoxide within the inverse micelles in which the surface-capped CdS nanoparticles coexist.     

Plant Growth Inhibitory Activity of L-Canavanine and Its Mode of Action

L-Canavanine is a nonprotein amino acid contained in jack bean [Canavalia ensiformis (L.) DC] and shows a plant inhibitory effect. The inhibitory effect was determined by an immersion test and a microdrop test that employed rice seedlings. L-Canavanine inhibited elongation of the second leaf sheath of rice seedlings more than other natural bioactive substances, such as salicylic acid and cinnamic acid. The modified microdrop test revealed that the mode of action of L-canavanine had no relation to gibberellin synthesis. In the microdrop test, the inhibitory effect of L-canavanine was decreased by simultaneous addition of L-arginine, an analog of L-canavanine. Free amino acid analysis of rice shoots clearly showed that L-canavanine induced an unusual accumulation of L-arginine. However, accumulation of L-arginine did not cause the inhibitory effect on plant growth. These results suggest that the mechanism of inhibition of L-canavanine is closely related to the inhibition of arginine metabolism.     

Alkali-metal ion/molecule association reactions and their applications to mass spectrometry

This review will be concerned primarily with thermal alkali-metal ion association reactions of the general type: A+ + M + N reversible (A + M)+ + N. Where A denotes a positively charged alkali metal ion, M is neutral species and N works as a third body. As indicated, most association reactions are reversible, and the A-M bond derives primarily from electrostatic forces whose energy (affinity) is typically 50 kcal/mol or less, often much less. The review includes reaction mechanism, instrumentation, and application to mass spectrometry, together with reaction rates and alkali ion affinities of the classified compounds.     

Study on chemical structures of poly (tetrafluoroethylene-co-perfluoroalkylvinylether) by soft-EB irradiation in solid and molten state

Poly (tetrafluoroethylene-co-perfluoroalkylvinylether) (PFA) was irradiated by soft electron beam (soft-EB) under nitrogen gas atmosphere in solid-state and its molten state, respectively. The changes of thermal property and chemical structures of irradiated PFA in solid-state and molten state were studied by differential scanning calorimetric analysis (DSC) and solid-state ¹⁹F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. By DSC analysis, the melting temperature shifted to lower temperatures, and crystallinity decreased with increasing soft-EB dose. By solid-state ¹⁹F MAS NMR spectroscopy, the new signals was observed and the detected new signals in irradiated PFA at 315 °C and at 30 °C were due to the tertiary carbon group with branching site (Y-type crosslinking site), perfluoro-propylene site and chain end methylene groups, respectively.Moreover, the molar ratio of perfluoroalkylvinylether (FAVE) structure to -CF₂- units decreased with increasing dose.