Improvement of Porous Si Luminescence Intensity Durability by Nitrogen Ion Irradiation Using an ECR Ion Source

We have investigated the effects of the porous Si surface passivation by oxygen or nitrogen ion processing on the photoluminescence (PL) intensity and its stability using an electron cyclotron resonance ion source. The results indicate that an anneal before exposure to ion beam causes a PL intensity enhancement upon exposure to oxygen or nitrogen ion beam. A combination of an anneal and a passivation by exposure to nitrogen ion beam enhances the PL intensity by a factor of 2.5 compared to the intensity of the initial as-anodized PS and the enhanced intensity is stabilized for more than 180 min under Ar⁺-laser illumination while oxygen-ion-exposed PS exhibits an enhancement in PL intensity only by 1.4 and a decay in PL intensity by 20% after 180 min Ar⁺-laser illumination. The results suggest that the reaction of nitrogen with a PS surface plays a key role for the PL intensity enhancement and stability.     

Surface hydrophilic–hydrophobic property on transparent mesoporous silica thin films containing chromium oxide single-site photocatalyst

Using a sol–gel/spin-coating method with organic template, the transparent mesoporous silica thin films containing chromium oxide moieties can be prepared on quartz plate. The spectroscopic characterization has revealed that these thin films contain isolated and tetrahedrally coordinated chromium oxide moieties (single-site photocatalyst) in their frameworks. Even before UV light irradiation these Cr-containing mesoporous silica (CrMS) thin films have demonstrated a hydrophilic surface property more strongly than Cr-containing non-porous silica films and mesoporous silica thin films without chromium oxide. Furthermore, the Cr-containing mesoporous silica thin films showed the super-hydrophilic property not only under UV light irradiation but also even under visible light irradiation from a fluorescent lamp. In the presence of ethylene gas, the polyethylene was successfully formed on the surface of the CrMS thin film under UV light irradiation. After the formation of polyethylene the surface property of the CrMS thin film was converted into hydrophobic while keeping its transparency. The isolated and tetrahedrally coordinated chromium oxide moieties are responsible for these photo-induced surface reactions.     

Clinical features of small hepatocellular carcinomas as assessed by histologic grades

This paper outlines three important issues in the clinical management of sexually transmitted diseases (STDs) in Papua New Guinea which have, until now, gone unrecognized or been neglected. Suggestions for possible solutions are made. The high prevalence of both chlamydial and trichomonal infections in women cannot be ignored. Both of these infections have been shown to increase the transmission of HIV. The current algorithm for the treatment of vaginal discharges does not include treatment for trichomonal infection in the first instance, yet trichomoniasis has been shown to be the most common STD in community studies both here and elsewhere. Trichomoniasis is usually asymptomatic in men, but still increases the risk of HIV transmission; furthermore, it causes illness in their female partners and thus needs to be treated. The current recommended regimens for the treatment of gonococcal and chlamydial infection are complex due to the number of drugs recommended for gonorrhoea to combat the problem of drug resistance, and the length of therapy for chlamydia. Compliance with such a regimen is likely to be poor, particularly in asymptomatic partners. We need to consider the relative advantages provided by a drug which could be given as a single oral dose for chlamydia, and perhaps for both infections. Azithromycin is one possibility, as it has been shown to be effective for chlamydial infection in numerous studies, and has been found satisfactory for gonorrhoea where local isolates were susceptible. Testing of a small number of isolates from Papua New Guinea has shown that azithromycin may be suitable for use here, but further susceptibility testing needs to be performed. Utilization of services for STDs, particularly by women, is extremely low. This is due to a combination of factors involving limited knowledge of symptomatology and its significance, the asymptomatic nature of many infections, the structure of the services, health worker behaviour, and social attitudes. To address these issues we must make modifications to STD service provision, as well as provide widespread information about the potentially serious consequences of contracting STDs, including both infertility and AIDS. Possible modifications to the services are discussed, and include making routine screening available for women through currently existing services such as family planning and antenatal clinics and considering the possibility of establishing Women's Health Clinics which would provide all primary reproductive health services in an integrated manner.     

Regio- and stereoselective propranolol metabolism by 15 forms of purified cytochromes P-450 from rat liver

Regio- and stereoselectivity of cytochrome P-450-mediated propranolol metabolism (4-, 5- and 7-hydroxylations and N-desisopropylation) was studied using 15 purified cytochrome P-450 species. With each purified cytochrome P-450 species, the regioselectivity was distinct and different between the two optical isomers used as substrates. The stereoselectivity was different depending on the position of propranolol to be metabolized. The regio- and stereoselectivity was altered when substrate concentration was altered, suggesting that the kinetics of the reactions are different depending on the positions of propranolol to be metabolized. Furthermore, the selectivity and its manner of alterations with substrate concentrations were different among all cytochrome P-450 species used. Propranolol, with its multiple metabolic pathways and optical isomers, is an extremely interesting substrate for characterization of cytochrome P-450 species.     

Millimeter-wave wide-band amplifiers using multilayer MMICtechnology

This paper describes millimeter-wave wide-band single-ended and balanced amplifiers using novel multilayer monolithic microwave/millimeter-wave integrated circuit (MMIC) technology. The fundamental characteristics of thin-film transmission lines and a 50-GHz-band multilayer MMIC directional coupler are described through measurements up to 60 GHz. A single-ended amplifier fabricated in a 1.1 mm×0.8 mm area, shows a gain of about 12 dB with a noise figure of better than 5 dB around 50 GHz. A balanced amplifier fabricated using the multilayer MMIC directional couplers and single-ended amplifiers, shows a gain of 10-17 dB with input and output return losses of better than 14 dB from 33 to 53 GHz. The transmission lines and directional couplers can be effectively combined with millimeter-wave active circuits without degrading the circuit performance or increasing the circuit area. To our knowledge, these are the first millimeter-wave active circuits employing multilayer MMIC technology     

Rate dependence on mechanical properties of unsaturated cohesive soil with stress-induced anisotropy

The strain rate during shearing has been shown in experimental studies to strongly affect the mechanical behaviour of soil. For saturated soil, sufficient knowledge has been obtained to achieve equilibrium conditions for the pore water pressure. Nevertheless, little is known about unsaturated soil. Therefore, this study used a hollow cylindrical torsional shear apparatus to investigate the rate dependence on the deformation and strength properties of unsaturated soil. First, unsaturated specimens were anisotropically consolidated with different directions of major principal stress to assess the rate dependence of the anisotropic behaviour. Then, the shear stress was removed to produce an isotropic stress state. Shearing was applied using the specimens to evaluate the strain rate effects on the mechanical properties of unsaturated cohesive soil. The results indicate that the secant shear modulus increased with the strain rate in both constant suction (CS) and constant water content (CW) conditions. The shear strength did not change with the strain rate under a CW condition, but it decreased with the strain rate under a CS condition.     

Photo-induced Surface Property on Transparent Mesoporous Silica Thin Films Containing Single-site Photocatalyst

The transparent Ti-containing or Cr-containing mesoporous silica thin films can be prepared on quartz plate using a spin-coating sol–gel method. The spectroscopic characterization has revealed that these thin films contain isolated and tetrahedrally coordinated titanium oxide moieties and chromium oxide moieties in their frameworks, respectively. These mesoporous silica thin films containing metal oxide moieties have demonstrated a strong hydrophilic surface property even before UV-light irradiation and the appearance of the super-hydrophilic property after UV-light irradiation. Especially, the Cr-containing mesoporous silica (CMS) thin film showed the super-hydrophilic property even under visible light irradiation. In the presence of ethylene gas, the polyethylene was successfully formed on the surface of the CMS thin film under UV-light irradiation. After the formation of polyethylene the surface property of the CMS was converted into hydrophobic while keeping its transparency. The isolated and tetrahedrally coordinated titanium oxide moieties and chromium oxide moieties are responsible for these photo-induced surface reactions.