Metabolism of 12-ketooctadecanoic acid byEscherichia coli K-12 andCandida tropicalis

The mode of degradation of long chain keto acids by two microorganisms was investigated.Escherichia coli K-12 converted 12-ketooctadecanoic acid to 4-ketodecanoic acid, accumulating some amounts of intermediates, 10-ketohexadecanoic, 8-ketotetradecanoic and 6-ketododecanoic acids. In contrast,Candida tropicalis completely metabolized the keto acid with transient accumulation of the metabolites mentioned above. The difference between the metabolism byE. coli of hydroxy acid and keto acid is that 12-hydroxyoctadecanoic acid is degraded as far as 6-hydroxydodecanoic acid, while 12-ketooctadecanoic acid can be degraded as far as 4-ketodecanoic acid.     

Radiation-induced graft copolymerization of butadiene to polyethylene and polypropylene

Polyethylene and polypropylene films were irradiated by γ-irradiation from a Co⁶⁰ source in butadiene gas flow and in liquid butaidne. Irradiating in the butadiene gas flow is particularly convenient because the gas state monomer is available directly and little homopolymer is produced. In this case, there is a retardative effect on the grafting near the surface of the film and the grafting rate shows the maximum values at 50–60°C. for high-density PE (PEH) and PP. Irradiating in the liquid butadiene decreases the retardative effect near the surface. The effect of dose rate I on the grafting rate Rp is represented by R_p ∞ I^1/4 in this case. The grafting rate is always higher in PEH than in low-density PE (PEL). Results of x-ray diffractometry and electron microscopy indicate that the grafting reaction occurs predominantly near the surface of the crystallite (lamella) of PE and the grafting rate is not affected by the overall crystallinity of the trunk polymer but by the configurational structure, such as the degree of branching or side-chain length.     

New annealing method and CaGe garnet film coercivity origin

A new annealing method which drastically reduces the coercivity of GaGe-garnet films grown by LPE has been developed. The as-grown films of (YSmLuCa)₃(FeGe)₅O₁₂ and (YEuTmCa)₃(FeGe)₅ O₁₂ are sealed with Y₂O₃ and metal Ca in an evacuated tube having three chambers. When heated, the tube is filled with Ca and O₂ gases which are supplied from the metal Ca and Y₂O₃, respectively. Ca and oxygen are believed to be incorporated into the film occupying the dodecahedral cation vacancies and oxygen vacancies, respectively. By this annealing, coercivities higher than 5.0 Oe are drastically reduced to less than 0.5 Oe. At the same time, the 4πMs and lattice constant af are decreased, while the Curie temperature T_c is increased. A point defect structure model containing c-site vacancies, oxygen vacancies and a-site Ge²⁺ ions is proposed. The origin of the coercivity is believed to be the oxygen vacancies.     

Effects of blood perfusion rate on the optimization ofRF-capacitive hyperthermia

The effects of the blood perfusion rate on the optimization of heating conditions in radio-frequency capacitive hyperthermia were examined using numerical simulations. When the blood perfusion rate in the tumor was smaller than approximately one-half that of normal tissues, optimal selective heating of the tumor was obtained     

A robust increase in expression of arc gene, an effector immediate early gene, in the rat brain after acute and chronic methamphetamine administration

The effect of acute and chronic administration of methamphetamine (METH) on the levels of activity-regulated cytoskeleton-associated protein (arc), an effector-immediate early gene, mRNA has been investigated in rat brain using in situ hybridization. Levels of arc mRNAs in the brain regions examined increased significantly from 0.5-1 h after an acute METH (4 mg/kg) administration compared with basal levels. The increase in arc mRNA continued by 3 h, and then subsided to basal levels by 6 h. The degree of increase in arc mRNA and the peak time after METH administration varied according to brain area. Arc mRNA in cerebral cortices showed robust increase 1 h after METH administration. In the striatum and hippocampus, it showed earlier and later increase, respectively, and its degree of both was less than in the cortices. Microscopic examination revealed that the METH-induced arc mRNAs in the parietal cortex were enriched in layers IV and VI, and those in the striatum existed mainly in the medium-sized neuron. Pretreatment with either 0.5 mg/kg SCH23390 or 0.25 mg/kg MK-801 almost completely blocked the enhanced striatal arc mRNA levels induced by acute METH administration, whereas such pretreatments only partially reduced the effect of METH in the cerebral cortical regions. In the chronic treatment experiment, the arc mRNA levels of the group that received chronic treatment with METH followed by a METH challenge showed an increase like seen after acute METH administration. Since previous studies proposed that arc is one of cytoskeleton-associated proteins and is selectively localized in neural dendrites, the results of the present study suggested that arc may play an important role in the synaptic plasticity underlying METH-induced adaptational changes including behavioral sensitization.