Rutile thin film responsive to visible light and with high UV light sensitivity

A transparent rutile thin film 100 nm thick was fabricated on a quartz glass substrate; it was responsive to visible light and had a higher sensitivity to UV light than an anatase thin film formed by sol–gel method under identical conditions. The crystal structure was determined by observations using X-ray diffraction, Raman spectra, and a transmission electron microscope. The oxygen/titanium ratio of the rutile thin films was 1.78 according to the XPS peaks. The photoreactivity and photoinduced hydrophilicity of the rutile thin films was examined by measuring the pseudo first-order rate for the decoloration of methylene blue in an aqueous solution and the water contact angle, respectively. The high photoreactivity and photosensitivity of the O-deficient rutile thin film, whose optical band edge and refractive index were 3.10 eV and 2.2, respectively, were due to electron traps and assisted by O-defects within the rutile particles.     

Correlation between thermal dissociation and chemical structure of blocked isocyanates

Thermal dissociation of blocked aliphatic isocyanates was investigated. It was found that the degree of dissociation is much affected by the structure of the isocyanates and blocking agents. These results were able to be related to the electron densities and to the thermal dissociation calculated by computer simulation.     

Biological response of guinea pig peritoneal macrophages to platelet-activating factor

We investigated the effects of platelet-activating factor (PAF) on guinea pig peritoneal macrophages. Specific and high-affinity binding sites for PAF were detected on guinea pig peritoneal macrophages. Scatchard analysis of PAF binding revealed high affinity binding sites (7.9×10⁴/cell) with a dissociation constant of 2.3×10⁻¹⁰ M. When treated with 10⁻⁹−10⁻⁵ M PAF, guinea pig peritoneal macrophages released hydrogen peroxide into the medium in a time-dependent manner. The release reaction upon stimulation with 10⁻⁵ M PAF reached a plateau within 30 min and the extent of release was twice as high as that when stimulated byN-formyl-L-methionyl-leucyl-L-phenylalanine (fMLP; 2 μM)-treated cells. Neither lysoPAF nor the PAF enantiomer was effective. PAF-induced H₂O₂ release was inhibited specifically by PAF antagonists, suggesting that PAF activated macrophages through binding to specific sites. Lysosomal enzyme (N-acetyl-β-D-glucosaminidase) was released from guinea pig peritoneal macrophages upon treatment with 10⁻⁵ M PAF for 60 min. Guinea pig peritoneal macrophages were treated with PAF for 8 hr and the conditioned medium was examined for cytokines. The medium exhibited cytocidal activity against mouse fibroblast L929 cells [tumor necrosis factor (TNF) activity], and this activity was comparable to that detected after treatment of cells with the bacterial lipopolysaccharide (LPS). Furthermore, the same conditioned medium also showed colony-stimulating factor (CSF) activity. Generation of these cytokines was stereospecific. Our findings suggest that PAF is a unique macrophage activator that potentiates both respiratory burst/lysosomal enzyme release (early-phase response) and monokine production/glucose consumption (late-phase response). Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl Ether Lipids, Tokyo, Japan, May 1989.     

Reversible transformation and fluorescence modulation in polymorphic crystals of n-butylammonium 2-naphthalenesulfonate

An organic salt composed of 2-naphthalenesulfonic acid and n-butylamine yielded polymorphic crystals: the block-like Form A and the plate-like Form B. The former was obtained from 1-propanol by slow cooling, while the latter was dominantly done from 1,4-dioxane, m-xylene and so on. Interestingly, the former was transformed to the latter by mechanical grinding and the reverse occurred by heat treatment at 120 °C. X-ray crystallographic studies clarified that the former has π–π interactions among naphthalene rings and hydrogen bonding network involving two oxygen atoms of sulfonate group, while the latter has CH–π interactions and the network involving three oxygen atoms. Luminescent properties were different in these crystals and continuously switched with the transformation.     

Radiation safety management of residual long-lived radioactivity distributed in an inner concrete wall of a medical cyclotron room

The depth distribution of residual long-lived radioactivity in the inner concrete wall of a medical cyclotron room was measured by assaying concrete cores. Seven long-lived radioactive nuclides ((46)Sc, (60)Co, (65)Zn, (134)Cs, (152)Eu, (22)Na and (54)Mn) were identified by gamma-ray spectrometry of the concrete samples. It was confirmed that the gamma-ray-emitting radionuclides induced by thermal neutrons through the (n, γ) reaction are dominant, and that the activity induced by thermal neutrons is greater at a depth of 10-30 cm, rather than at the surface of the concrete, and decreased exponentially beyond a depth of ~40 cm. Although the specific activity at the surface was greater than the clearance level for radioactive waste indicated in IAEA RS-G-1.7, the mean specific activities in the walls and floor were less than the clearance level.     

Study on rapid analysis method of pesticide contamination in processed foods by GC-MS and GC-FPD

A simple and rapid method using GC-MS and GC-FPD for the determination of pesticide contamination in processed food has been developed. Pesticides were extracted from a sample with ethyl acetate in the presence of anhydrous sodium sulfate, then cleaned up with a combination of mini-columns, such as macroporous diatomaceous earth, C18, GCB (graphite carbon black) and PSA. Recovery tests of 57 pesticides (known to be toxic or harmful) from ten kinds of processed foods (butter, cheese, corned beef, dried shrimp, frozen Chinese dumplings, grilled eels, instant noodles, kimchi, retort-packed curry and wine) were performed, and the recovery rates were mostly between 70% and 120%. This method can be used to judge whether or not processed foods are contaminated with pesticides at potentially harmful levels.     

Influence of initial deflection of plate girder webs on fatigue crack initiation

When a thin-walled plate girder is subjected to repeated bending, it is possible that three types of fatigue cracks may be initiated. Fatigue cracks initiated in the tension flange and at the terminal point of the transverse stiffeners in the tension zone of the web are the most common fatigue cracks in thick beams. In addition, fatigue cracks which occur at the toe on the web side of fillet welds connecting a compression flange to a web, can only be observed in thin-walled plate girders. The crakcs are caused by secondary bending stresses produced by the out-of-plane movement of unavoidable initial deflections of the web under repeated in-plane bending.This influence of initial web deflections on the out-of-plane deformations of the web or the secondary bending stresses at the toe is examined by finite element analysis. Comparisons between the analytical results and the past fatigue test results conclude that not only the magnitudes of the initial web deflections, but also their shapes will greatly influence an increase in the secondary bending stresses and then the initiation of the fatigue cracks along the upper boundary of the web.     

Thermal degradation of poly(vinyl chloride) in oxidative and non-oxidative atmospheres

The thermal degradation of PVC has been studied. The formation of benzene and crosslinkages are closely correlated, and the critical temperature of the benzene evolution is found to be about 583 K. Thermodynamic functions have been estimated from the specific reaction rate of benzene formation, and the mechanism of cyclization is discussed.