Characteristics of peroxisome proliferation: co-induction of peroxisomal fatty acid oxidation-related enzymes with microsomal laurate hydroxylase

The profile of the changes in the peroxisomal fatty acid oxidation activity in rat liver was compared with that in microsomal omega-oxidation under various conditions such as a 2-week administration of phenoxyacetic acid derivatives and perfluorinated compounds, short and long-term administration of clofibrate and bezafibrate, high-fat diet feeding, starvation and diabetes. The results were summarized as follows: 1) when phenoxyacetic acid derivatives and perfluorinated compounds were administered, there was a significant correlation in the increase of the activities between peroxisomal fatty acid oxidation and microsomal omega-oxidation. 2) On the long-term administration (79 weeks) of peroxisome proliferators the activities of the enzymes were significantly reduced, but the levels were still higher than the control level in a similar manner. 3) On high-fat diet feeding the patterns of the changes in the activities of peroxisomal fatty acid oxidation, carnitine acetyltransferase and microsomal omega-oxidation were similar to each other, differing from the changes in the activities of microsomal aminopyrin demethylase and mitochondrial carnitine palmitoyltransferase. 4) Under starved and diabetic conditions, co-induction of peroxisomal fatty acid oxidation and microsomal omega-oxidation was observed. From these results it is suggested that 1) the biosynthesis of these enzymes would be regulated on the gene expression of the nearby domain and 2) peroxisomal fatty acid oxidation and microsomal omega-oxidation were co-operatively regulated in order to achieve fatty acid metabolism smoothly.     

Rheology of sols and fiber drawing

The investigations on the viscosity of the metal alkoxide solutions in the course of hydrolysis and condensation reactions leading to the gelation of sols have been reviewed. All the solutions which gel finally show a continuous increase in viscosity with time until they gel at a certain viscosity higher than about 100 P which is dependent on the composition of the starting solution. When a metal alkoxide solution is catalyzed with an acid and its water content is small at less than 4 or 5 in the water to alkoxide mol ratio, the solution exhibits spinnability at viscosities above about 10 P and becomes drawable into gel fibers, whereas no spinnability appears when a solution contains a large amount of water or is catalyzed with an alkali like ammonia.

The investigations on the relation between the reduced viscosity and the concentration or the relation between the intrinsic viscosity and the number-averaged molecular weight have made it clear that the spinnable silicon alkoxide solutions have long-shaped siloxane particles and non-spinnable solutions have round particles.

It has been established that spinnable solutions exhibit Newtonian flow behavior up to high viscosities, where fibers can be drawn, while non-spinnable solutions exhibit marked structural viscosity and, sometimes, thixotropy. Similar behavior is confirmed in the alumina solutions prepared from inorganic salts. It has been reported that the viscosity measurements provide information on the rate of the reaction leading to gelation. It is also known that the viscosity of the alkoxide solution controls the thickness of the thin coating film made by the dip-coating technique using an alkoxide solution.     

Fabrication of silver nanoparticles deposited on boehmite sol for surface enhanced Raman scattering

The composite consisting of silver nanoparticles deposited on boehmite hybrid was synthesized by NaBH₄ reduction technique. The morphology of the composite was studied by TEM, UV/Vis spectrophotometer and particle sizer. The size of the silver nanoparticles deposited on the surface of the boehmite ranged from 10 nm to 100 nm. The contact of silver nanoparticles increased by means of deposition of silver nanoparticles on the boehmite sol and the aggregation of the composites. This leads to the appearance of a shoulder at 450 nm in the UV-Vis absorption spectra with the addition of 0.15 mg and 1.5 mg boehmite. It was found that the intensity of the SERS in the case of the composite was higher than for silver colloids consisting of a concentration of silver greater than 3.2 mM.     

Sol–gel and transfer technique for fabricating dual ceramic thin film patterns on plastics

A technique that realizes alternating, two kinds of ceramic ribbons on plastics is proposed. An Si(100) plate with periodic trenches coated with a polyimide (PI)-polyvinylpyrrolidone (PVP) mixture layer was used as the mother substrate. An indium–tin–oxide (ITO) thin film was deposited on the mother substrate by the sol–gel method with a firing process, followed by transferring it to a polycarbonate (PC) substrate by melting the PC surface in contact with the ITO thin film. This resulted in patterned ITO ribbons on the PC substrate where the ridges of PC were formed between the ribbons. A ZnO thin film was prepared on a flat Si(100) substrate coated with a PI-PVP mixture layer, followed by firing, and then was transferred on the PC ridges in the same manner, resulting in alternating ITO and ZnO ribbons on the PC substrate. The technique proposed here allows dense, alternating ceramic ribbons to be fabricated on plastics irrespective of the combinations of ceramics and plastics.     

Vanishing hall coefficient in the extreme quantum limit in photocarrier-doped SrTiO3

We explore the extreme quantum limit of photogenerated electrons in quantum paraelectric SrTiO3. This regime is distinct from conventional semiconductors, due to the large electron effective mass and large dielectric constant. At low temperature, the magnetoresistance and Hall resistivity saturate at a high magnetic field, deviating from conventional behavior. As a result, the Hall coefficient vanishes on the scale of the ratio of the Landau level splitting to the thermal energy, indicating the essential role of lowest Landau level occupancy, as limited by thermal broadening.     

Protein release from yeast cells as an evaluation method of physical effects in ultrasonic field

The release rate of intercellular protein from yeast cells by the ultrasonic action is proposed as a method for evaluating the physical (mechanical) effects of the ultrasonic field. The protein concentration was quantitatively determined using UV absorbance of proteins by spectrophotometry. The detail of the procedures, such as the effects of the origin of yeast cells, pretreatment of the cells, and the wavelengths for spectrophotometric determination of protein content, are examined. The effectiveness of the proposed evaluation method was experimentally demonstrated by changing the irradiation conditions of ultrasound, such as the concentration of yeast cells, temperature, ultrasound power, types of sonicator, and the superposition with the mechanical mixing. The results validate the usefulness of the proposed evaluation method for the quantification of the physical effects of ultrasound fields. Also, the range of cavitational effects of ultrasound sensed by the evaluation procedures were discussed.     

Numerical simulations of acoustic cavitation noise with the temporal fluctuation in the number of bubbles

Numerical simulations of cavitation noise have been performed under the experimental conditions reported by Ashokkumar et al. (2007) [26]. The results of numerical simulations have indicated that the temporal fluctuation in the number of bubbles results in the broad-band noise. “Transient” cavitation bubbles, which disintegrate into daughter bubbles mostly in a few acoustic cycles, generate the broad-band noise as their short lifetimes cause the temporal fluctuation in the number of bubbles. Not only active bubbles in light emission (sonoluminescence) and chemical reactions but also inactive bubbles generate the broad-band noise. On the other hand, “stable” cavitation bubbles do not generate the broad-band noise. The weaker broad-band noise from a low-concentration surfactant solution compared to that from pure water observed experimentally by Ashokkumar et al. is caused by the fact that most bubbles are shape stable in a low-concentration surfactant solution due to the smaller ambient radii than those in pure water. For a relatively high number density of bubbles, the bubble–bubble interaction intensifies the broad-band noise. Harmonics in cavitation noise are generated by both “stable” and “transient” cavitation bubbles which pulsate nonlinearly with the period of ultrasound.     

Dependence of sonochemical parameters on the platinization of rutile titania – An observation of a pronounced increase in photocatalytic efficiencies

Using a standing wave sonochemical reactor (SWSR), the influences of parameters of ultrasonic power input, sonication time, sonication temperature and the amount of propanol (which generates the reducing radicals) were systemically investigated to ascertain and optimize the best conditions for the sonochemical reduction of Pt from its precursor hexachloroplatinic acid and then its deposition on rutile TiO₂ (platinization of rutile titania) catalysts. Catalytic activity of the prepared platinized catalysts was tested in the reaction of methyl orange degradation. The results of photocatalytic activity study in the degradation of methyl orange further demonstrate that sonochemically as-prepared Pt/TiO₂ catalysts show a pronounced increase (～2 times) in photodegradation, even with a deposition of small amounts of platinum (1.4 wt.%), as compared to the unsupported or naked rutile titania. Although there are various parameters that influence the sonochemical platinization of rutile titania, the present optimization results clearly indicate that the best photocatalytic degradation of methyl orange can be obtained when the experimental conditions of the preparation were with an input power of 50 W, an initial hexachloroplatinic acid volume of 70 ml (which results into 1.4 wt.% Pt on TiO₂), sonication time of 90 min, 0.18 g of propanol and a temperature of 10 °C were adopted. The method of ultrasound application to prepare metal supported semiconductors has many advantages such as convenience, safety and high efficiency. Furthermore, it is hopeful that this optimization study can also be extended to the generation of similar metal supported semiconductors.