Selective pyrolysis of polystyrene to that with a desired low polymeric degree

To obtain low polymeric polystyrene (PS), pyrolysis of high polymeric PS in solution was studied in the temperature range from 290 to 400°C by using additives or acid catalysts. The low polymeric PS targeted here was that with average molecular weight of 10⁴. When the feed PS was pyrolyzed in tetralin by adding sulfur or diphenyl disulfide, the molecular weight of PS decreased greatly, even at lower temperatures, and the desired low polymeric PS was formed in a relatively large amount at the temperatures below 350°C. The degradation behavior was able to be explained in terms of a random polymer chain scission mechanism initiated by sulfur radicals formed from the additives. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2299–2305, 1998     

Fundamental combustion characteristics of palm methyl ester (PME) as alternative fuel for gas turbines

To investigate the combustion characteristics of palm methyl ester (PME) as an alternative fuel for gas turbines, combustion experiments at atmospheric pressure using high-temperature air (673 K) were performed. Chemical equilibrium calculations and investigations of fuel atomizing characteristics using a laser diffraction spray analyzer (LDSA) were also conducted. The results show that combustion characteristics of PME are similar to those of diesel fuel. Furthermore, it is indicated that NO_x emissions can be reduced by using PME instead of diesel fuel for gas turbines.     

Transparent ultrafine Yb3+:Y2O3 laser ceramics fabricated by spark plasma sintering

Conventional ceramic processing techniques do not produce ultrafine‐grained materials. However, since the mechanical and optical properties are highly dependent on the grain size, advanced processing techniques are needed to obtain ceramics with a grain size smaller than the wavelength of visible light for new laser sources. As an empirical study for lasing from an ultrafine‐grained ceramics, transparent Yb³⁺:Y₂O₃ ceramics with several doping concentrations were fabricated by spark plasma sintering (SPS) and their microstructures were analyzed, along with optical and spectroscopic properties. Laser oscillation was verified for 10 at.% Yb³⁺:Y₂O₃ ceramics. The laser ceramics in our study were sintered without sintering additives, and the SPS produced an ultrafine microstructure with an average grain size of 261 nm, which is about one order of magnitude smaller than that of ceramics sintered by conventional techniques. A load was applied during heating to enhance densification, and an in‐line transmittance near the theoretical value was obtained. An analysis of the crystal structure confirmed that the Yb³⁺:Y₂O₃ ceramics were in a solid solution. To the best of our knowledge, this study is the first report verifying the lasing properties of not only ultrafine‐grained but also Yb‐doped ceramics obtained by SPS.     

Ex situ and in situ characterization studies of spin-coated TiO2 film electrodes for the electrochemical ozone production process

An electrode composed of silicon/titanium oxide/platinum/titanium dioxide (Si/TiO_X/Pt/TiO₂) was fabricated by spin-coating TiO₂ multilayers on a Si/TiO_X/Pt substrate and was used in electrochemical ozone production (EOP). EOP was realized when the Si/TiO_X/Pt substrate was completely covered with the TiO₂ film and a current efficiency of 7% was achieved at a low current density of 26.7 mA cm⁻² in 0.01 M HClO₄ at 15 °C. The TiO₂ film was found to be of an anatase-type TiO₂ and that to comprise aperture structures from the X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations. Moreover, the fabricated TiO₂ film was found to be an n-type semiconductor by photoelectrochemical measurements. The high efficiency at a low current density of EOP on the TiO₂ n-type semiconductor was explained to result from the electron transfer through the TiO₂/HClO₄ interface as tunneling current. When the tunneling current passes through a depletion layer of TiO₂, the electrode potential is necessarily high enough to facilitate EOP.     

The preparation of visible emulsions and its applications to cosmetics

We developed a preparation method for visible emulsion droplets (0.05–3 mm) consisting of a solid type oil and a liquid type oil. It was found that (1) using amphiphiles as the solid oil gave a spherical and visible sized particle and (2) behenyl alcohol was the most preferable amphiphile to make a large sized particle. DSC measurement and microscopic observation of the particle showed that the amphiphilic solid oil built a shell on the outer side of the particle and the shell protected the emulsion against aggregation and coalescence. It was found that the preparation of an extremely large emulsion could create innovative functions in the cosmetic field. The visible sized emulsion could provide a freshening feel in the early stages of the application and an emollient feel after rubbing into the skin. Furthermore, since this emulsion could protect an unstable lipophilic material from hydrolysis, it offers a suitable storage for useful cosmetic ingredients such as lipophilic drugs and hydrophobic powders.     

In vitro and in vivo antioxidant properties of ferulic acid: A comparative study with other natural oxidation inhibitors

Ferulic acid exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. However, in vitro antioxidant properties of ferulic acid have not been elucidated in detail. Evidence that polyphenols, including ferulic acid, act as antioxidants in vivo is also limited. In order to elucidate in more detail the scientific background of antioxidant activities of ferulic acid, we carried out in vitro and in vivo experiments. We focused on superoxide anion scavenging activity, xanthine oxidase inhibition activity, and chain-breaking activity. The combined antioxidant activity from radical scavenging and xanthine oxidase inhibition of ferulic acid was much weaker than that of (−)-epigallocatechin gallate (EGCG) and ascorbic acid. On the other hand, EGCG, ascorbic acid and ferulic acid exhibited chain-breaking activity and prevented ischaemia-reperfusion-associated intestinal injury. Chain-breaking activity may play a contributory role in the protective effect of ferulic acid on oxidative injury in humans and in in vivo studies.     

Kinking and Cracking Caused by Slip in Single Crystals of Silicon Carbide

α-SiC single crystals were compressed parallel to the basal plane, (0001), at temperatures between 900° and 1500°C. Plastic deformation by slip on the basal planes which accompanied kinking occurred above 1000°C. At kink boundaries, two kinds of cracks were observed. One was the cracks elongated parallel to the basal plane. This kind of crack was initiated by the tensile stress produced by piled-up dislocations on the basal planes against a kink boundary. The other was on a kink boundary, and was induced by the stress of dislocations, heterogeneously distributed on the kink boundary. The initiation of cracks produced by dislocations was considered to be a possible cause of fracture in polycrystalline SiC at high temperatures.     

Fat Utilization in Healthy Subjects Consuming Diacylglycerol Oil Diet: Dietary and Whole Body Fat Oxidation

Several studies in animals and humans have reported beneficial effects of diacylglycerol (DAG) on lipid and energy metabolism. We assessed the effect of DAG versus triacylglycerol (TAG) treatment on total energy expenditure (TEE), total fat oxidation (Fox) and respiratory quotient (RQ), and measured the oxidation rate of each oil using a respiratory chamber and the 13C-stable isotope. Eleven healthy subjects participated in a double-blind, randomized crossover study. Subjects consumed an energy maintenance diet consisting of 55% of total calories from carbohydrate, 15% from protein and 30% from fat during both the 3-day pre-chamber and 36-h chamber period. Fifty percent of the fat was test oil, containing either DAG oil or TAG oil. The oxidation rate of ingested test oils was determined by monitoring 13CO2 excretion in the breath from 13C-labeled diolein or 13C-labeled triolein. There were no significant differences in TEE, RQ and total Fox between the DAG and TAG treatment in the overall analysis. In the subgroup analysis, DAG treatment decreased RQ significantly in subjects with a high fat ratio (HFR) compared to TAG treatment. In addition, ingested diolein oxidation in DAG treatment was significantly faster than triolein oxidation in TAG treatment in the HFR group. Enhanced fat utilization with DAG treatment and rapid oxidation of ingested DAG may, at least in part, explain the greater loss of body weight and body fat related to DAG consumption found in the weight-loss studies.     

An analysis of reverse osmotic characteristics of American-standard type tubular module

Reverse osmosis experiments were carried out with a TM-5-14 tubular module to obtain its reverse osmotic characteristics. Analysis of the data based on the general equations proposed by Ohya and Sourirajan (5) gives membrane characteristic constants, A = 0.845 x 10^?6 g·mole H₂O/cm²·atm·s, and (D_AM/ kδ) = 1.38 x 10^-5cm/sec. The experimental data of mass transfer coefficients agree well with the equation proposed by Linton and Sherwood (7).     

A software technique to improve lifetime of caches containing ultra-leaky SRAM cells caused by within-die Vth variation

Exceptionally leaky transistors are increasingly more frequent in nanometer-scale technologies due to lower threshold voltage and its increased variation. SRAM cells containing such transistors suffer from accelerated aging due to electromigration intensified by higher currents continuously flowing through thin metals such as vias and contacts. Such cells do not violate target delay since leaky transistors are faster than ideal ones, and hence they are not faulty to be worth replacing with redundant rows and columns, which may also themselves contain exceptionally leaky transistors. Moreover, their number is growing so fast that makes redundancy ineffective. We show that in SRAM cells leakage current depends on the value stored in the cell and propose a software-based runtime technique that suppresses such abnormal leakages in the standby mode by storing safe values in the corresponding cache lines. Consequently, the lifetime of such caches is restored when used in long-standby applications. Moreover, energy dissipation in the standby mode is reduced by this technique if the standby duration is more than a few seconds. Analysis proves the performance penalty is, in the worst case, linearly dependent to the number of so-cured cache lines.