9H-xanthene-2,7-diols as antioxidants for autoxidation of linoleic acid

The antioxidant activities of 9H-xanthene-2,7-diols and α-tocopherol were studied during the oxidation of linoleic acid in a homogeneous solution and in an aqueous micelle dispersion. The antioxidant activities of 9H-xanthene-2,7-diols for both systems were 1.0–2.4 times greater relative to α-tocopherol. In addition, the 1,3,4,5,6,8-hexamethylxanthene-2,7-diol showed less cytotoxicity toward human fibroblasts than did 2,6-di-t-butyl-4-methylphenol.     

Dynamic behavior of an all-optical inverter using transverse-mode switching in 1.55-/spl mu/m vertical-cavity surface-emitting lasers

An all-optical inverter using transverse-mode switching of a 1.55-/spl mu/m vertical-cavity surface-emitting laser is demonstrated. When an external light is injected to a first high-order mode, the output power of the fundamental mode is strongly suppressed due to injection locking resulting in a large extinction ratio of over 20 dB. Waveform inversion is demonstrated for the input signal of a 5-GHz sinusoidal wave.     

Temperature dependency of bound water of cellulose studied by a high-resolution NMR spectrometer

The widths at half-value of high-resolution NMR spectra of bound water of cellulose were studied in relation to the temperature change. Two points were made clear: First, the amount of bound water of the cellulose sample can be pointed out with higher accuracy the lower the temperature of the measurement. Second, it is possible to determine in a simple manner the boundary temperature T_c at which water molecules become bound by the cellulose. T_c is characteristic of the cellulose sample of a given water content and corresponds to the glass transition temperature of the water-containing sample. The measurements appear to be readily applicable to other hydrophilic polymers.     

Kinetic study of thermostable L-threonine dehydrogenase from an archaeon Pyrococcus horikoshii

In the genome data base of the hyperthermophilic archaeon Pyrococcus horikoshii, an open reading frame with sequence homology to a gene encoding alcohol dehydrogenase was found. It was demonstrated that the encoded enzyme was a thermostable L-threonine dehydrogenase which can oxidize the hydroxy alkyl residue of L-threonine associated with the reduction of NAD+ or NADP+. This enzyme is a member of the zinc-containing L-threonine dehydrogenase family. One enzyme molecule contained one zinc atom, and this metal was considered to contribute to the hyperthermostablility of the enzyme. The reaction of the enzyme proceeded via a sequential mechanism. The Michaelis constants (Km) for L-threonine and NAD+ were 0.013 and 0.010 mM, respectively, and the maximum reaction rate (Vmax) was 1.75 mmol NADH formed/min/mg-protein at 65 degrees C. The Km values for both L-threonine and NADP+ were larger than those for L-threonine and NAD+ with a similar Vmax value. These results indicate that the enzyme has lower affinity to NADP+ than to NAD+, and the binding affinity for L-threonine depends on the coenzymes.     

A Gamma Ray Probe for the Detection of Ocular Melanomas

A specially designed scintillation probe has been assembled and applied in a promising diagnostic study of malignant melanoma in the human eye. When used in conjunction with a new radiopharmaceutical agent recently developed at The University of Michigan, 125I labeled chloroquine analog, the probe permits simple and nonsurgical gamma ray counting as a substitute for more elaborate techniques required in 32p beta scanning for the same prupose. Preferential uptake of the agent in ocular melanomas has been previously reported using a modified 5-inch NaI (Tl) crystal scanner as the detector. We have realized a substantial improvement in both sensitivity and reproducibility by substituting a hand-held probe placed in contact with the patient's closed eyelid. The counting rate over each eye is followed for a period ranging from 3 to 21 days after dosage. A melanoma in one eye gives rise to an enhanced rate over that eye. Data are presented on a total of 12 patients, including two with confirmed ocular melanomas. In both of these cases, the involved eye consistently shows a significantly greater activity than the opposite eye. In the remaining cases considered "negative", measured eye-to-eye asymmtries are much lower, and a measure of the variance associated with these cases is presented.     

Exploiting Context-Awareness in Cluster-Based Wireless Sensor Networks

Most of the wireless sensor network's (WSN's) applications require getting accurate information as well as uninterrupted, prolonged service life. Among the constituting elements of WSN, an efficient routing protocol plays a significant role in attaining such service requirements. In this article, an energy efficient routing protocol, context-aware clustering hierarchy (CACH), is proposed where cluster formation is based on the context of the environment. Moreover, a technique is utilized to avoid similar data traffic across the network. The performance in the simulation shows energy saving which ensures prolonged service life. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Characteristics of neutralization of acids by newly isolated fungal cells

Soil microorganisms play an important role in maintaining soil pH at levels suitable for other soil organisms. To clarify the biological neutralization mechanism in soil, we isolated soil microorganisms showing a high ability to neutralize acids and studied their characteristics. From our taxonomic study, three isolated strains were identified as filamentous fungi, namely Mucor sp., Aspergillus fumigatus, and Aureobasidium pullulans. These strains could secrete basic materials, such as ammonia, for neutralization, grow in the medium at pH 4.0 and increase the pH of the medium to approximately 8.0. These microbial cells could neutralize not only nitric acid but also sulfuric and hydrochloric acids. The strains could also grow by utilizing nitric acid as a sole nitrogen source. In the soil containing these organisms, the pH was maintained in the neutral range by the buffering action of basic materials that they secrete. These results suggest that these fungal cells are useful for protecting the soil from acidification by acid rain.