Serotype-specific amplification of Rickettsia tsutsugamushi DNA by nested polymerase chain reaction

Polymerase chain reaction (PCR) with nested primer pairs was used to diagnose scrub typhus and identify the Rickettsia tsutsugamushi serotype. The primer pairs used for PCR were designed on the basis of the nucleotide sequence of the gene that encodes the 56-kDa antigen. Serotype-specific primers were used in the second PCR amplification. Five serovariants, the Gilliam, Karp, Kato, Kawasaki, and Kuroki strains of R. tsutsugamushi, were identified by nested PCR. In addition, the serotype identified by PCR with DNA from blood clots was the same as that of the strain isolated from five patients with scrub typhus. These findings indicate that this method is useful for diagnosis and identification of the rickettsial serotype in infected patients.     

Containerless solidification of highly undercooled mullite melts: Crystal growth behavior and microstructure formation

A mullite (3Al₂O₃·2SiO₂) sample has been levitated and undercooled in an aero-acoustic levitator, so as to investigate the solidification behavior in a containerless condition. Crystal-growth velocities are measured as a function of melt undercoolings, which increase slowly with melt undercoolings up to 380 K and then increase quickly when undercoolings exceed 400 K. In order to elucidate the crystal growth and solidification behavior, the relationship of melt viscosities as a function of melt undercoolings is established on the basis of the fact that molten mullite melts are fragile, from which the atomic diffusivity is calculated via the Einstein-Stokes equation. The interface kinetics is analyzed when considering atomic diffusivities. The crystal-growth velocity vs melt undercooling is calculated based on the classical rate theory. Interestingly, two different microstructures are observed; one exhibits a straight, faceted rod without any branching with melt undercoolings up to 400 K, and the other is a feathery faceted dendrite when undercoolings exceed 400 K. The formation of these morphologies is discussed, taking into account the contributions of constitutional and kinetic undercoolings at different bulk undercoolings.     

Tunable laser for sensing atmospheric transmission in the infrared region of 11 ∼ 16 µm

We succeeded in observing the continuously tunable, pulsed InSb SFR (Spin-Flip Raman) laser emission in the infrared region of 11～16µm (11.4～16.3µm) from only one InSb device, merely by adjusting the pumping wavelength (11 lines from the infrared NH₃ laser) and the applied magnetic field (0～80 kGauss).     

Permeation of Zidovudine and Probenecid from Oily Bases Containing Alcohols Through Rat Skin

Permeation of zidovudine (3'-azido-3'-deoxythymidine, AZT) and probenecid from oily bases containing an alcohol through rat skin was examined. Isopropyl myristate (IPM), as an oily vehicle, showed a penetration enhancing effect for AZT and probenecid. Ethanol, n-propanol, and n-butanol were used as additives in IPM and were examined for their own permeation and the enhancing effect on the permeation of AZT and probenecid. The skin permeation of AZT and probenecid from IPM was enhanced by addition of the alcohol in IPM. The degree of the enhancement was decreased with increasing lipophilicity of the alcohol used. me permeation rate of the drug from those systems was shown to be governed by penetration-enhancing effects of the oily base and alcohol, and the penetration of the alcohol itself through the skin.     

A wide-bandwidth low-noise InGaAsP-InAlAs superlattice avalanchephotodiode with a flip-chip structure for wavelengths of 1.3 and 1.55μm

The authors reports the fabrication of a flip-chip InGaAsP-InAlAs superlattice avalanche photodiode using gas source molecular beam epitaxy. The incident light reaches the InGaAs photoabsorption layer through the InP substrate and an InGaAsP-InAlAs superlattice multiplication region which are transparent for wavelengths of 1.55 and 1.3 μm. The light reflection by the electrode enables the absorption layer to be as thin as 0.8 μm without significantly reducing the quantum efficiency. A maximum bandwidth of 17 GHz was obtained at a low multiplication factor because the transit time through the absorption layer is reduced     

Safety evaluation on the depressurization accident in the gas turbine high temperature reactor (GTHTR300)

Japan Atomic Energy Agency has been developing a gas turbine high temperature reactor (GTHTR300) with electric power of approximately 300 MW. One of the unique safety design concepts of this system is that events with frequency of occurrence of higher than 10⁻⁸/reactor-year are evaluated as design basis events in order to show that the frequency of large amount of FP release is less than 10⁻⁸/reactor-year. According to this concept, a depressurization accident by a large break of helium piping is postulated as a design basis event. This accident is one of the most serious accidents in the high-temperature gas-cooled reactors from the viewpoint of loss of coolability. The safety evaluation on the accident was conducted based on the actual design of the system. The short-term and long-term behaviors of fuel temperature after occurrence of the accident, internal pressure of the reactor building, oxidation behavior of fuels and graphite structures were evaluated and exposure dose of general public was also estimated using the results of evaluation of fuel temperature and fuel failure by oxidation. All of the evaluation results meet the safety criteria and feasibility of the GTHTR300 was shown by this study.     

Theory and characteristics of novel variable reluctance 1X resolver

Although brushless resolvers have been used widely as angular position transducers, they are expensive due to their intricate construction, involving a rotary transformer to supply the exciting coils wound on the rotor poles with the current. It is shown theoretically in this paper that the resolver without rotary transformer or brushes can be realized by simple construction, which consists of the stator core with both 4-poles exciting windings and 2-poles output ones and the rotor core carrying no windings. In this resolver the rotor core has minimum gap at one side and a maximum gap at another side of the diameter. It is characterized by an outer surface form that makes the fluctuation part of gap permeance very in proportion to cos θ, where θ represents the angular position of a point in the air gap with respect to the origin on the rotor, the point of minimum air gap. The method determining the rotor form to embody the aforementioned gap permeance variation is also shown. It has been confirmed not only by simulation but also experiment that the 2-phase output voltages of a model designed based on the theory have sinusoidal waveforms with very small harmonic contents. Moreover, the rotor position detected by processing the output voltages through the conventional resolver/digital converter was within acceptable engineering accuracy.