Characterization of E- and Z-ajoene obtained from different varieties of garlics

Synthesised E- and Z-ajoene were used to determine their amounts in food oils containing various fresh garlics. The best yield of E-ajoene (172.0 μg/g of garlic) and Z-ajoene (476.0 μg/g of garlic) was obtained from freshly prepared Japanese garlic with rice oil which was heated at 80 °C. Determination of E- and Z-ajoene from soybean oil containing 15% Japanese garlic samples prepared at 80 °C for 0.5 h gave the amount of E-ajoene (170.0 μg/g of garlic) and Z-ajoene (127.0 μg/g of garlic). After 9-month storage, 54.0% E- and 11.0% Z-ajoene remained in Japanese garlic with rice oil. Ajoene (0.1 mM) in ethyl acetate was incubated under UV-light (253.7 nm) for 3 days, 81.7% E- and 56.9% Z-ajoene remained. 4.3% and 0.5% E- and Z-ajoene remained when ajoene (0.1 mM in ethyl acetate) was incubated at 100 °C.     

A new technique for large-area thin film CdS/CdTe solar cells

The atmospheric pressure CSS method has been developed as a reproducible and efficient process. Thin film CdTe grown under atmospheric pressure has a rough surface morphology. The density of carbon black powder in the graphite carbon paste for screen printing is a key factor in reducing the series resistance of the device with rough surface CdTe. Using graphite carbon paste with 7 wt% carbon black powder has resulted in cells with a relatively low back contact resistance. A highly efficient large-area CdS/CdTe solar cell (11.0%, 5327 cm²) sub-module has been fabricated using the new technique.     

Mapping and control of atomic force on Si(1 1 1)square root(3) x square root(3)-Ag surface using noncontact atomic force microscope

We demonstrated the possibility of measuring the three-dimensional force-related map with true atomic resolution between an Si tip and Si(1 1 1)square root(3) x square root(3)-Ag sample surface by measuring the tip-sample distance dependence of noncontact atomic force microscope (NC-AFM) image, i.e. atomically resolved atomic force spectroscopy. Furthermore, we demonstrated the possibility of controlling the interaction force between the atom on the tip apex and a sample atom of Si(1 1 1)square root(3) x square root(3)-Ag surface on an atomic scale by placing an Ag atom on the Si tip apex instead of Si atom.     

Processing of ethanol fermentation broths by Candida krusei to separate bioethanol by pervaporation using silicone rubber‐coated silicalite membranes

BACKGROUND: Pervaporation employing ethanol‐permselective silicalite membranes as an alternative to distillation is a promising approach for refining low‐concentration bioethanol solutions. However, to make the separation process practicable, it is extremely important to avoid the problems caused by the adsorption of succinate on the membrane during the separation process. In this work, the pervaporation of an ethanol fermentation broth without succinate was investigated, as well as the influence of several fermentation broth nutrient components. RESULTS: Candida krusei IA‐1 produces an extremely low level of succinate. The decrease in permeate ethanol concentration through a silicone rubber‐coated silicalite membrane during the separation of low‐succinate C. krusei IA‐1 fermentation broth was significantly improved when compared with that obtained using Saccharomyces cerevisiae broth. By treating the fermentation broth with activated carbon, bioethanol was concentrated as efficiently as with binary mixtures of ethanol/water. The total flux was improved upto 56% of that obtained from the separation of binary mixtures, compared with 43% before the addition of activated carbon. Nutrients such as peptone, yeast extract and corn steep liquor had a negative effect on pervaporation, but this response was distinct from that caused by succinate. CONCLUSION: For consistent separation of bioethanol from C. krusei IA‐1 fermentation broth by pervaporation, it is useful to treat the low nutrient broth with activated carbon. To further improve pervaporation performance, it will be necessary to suppress the accumulation of glycerol. Copyright © 2009 Society of Chemical Industry     

Effects of heating rate on microstructure and transparency of spark-plasma-sintered alumina

Commercial alumina powder was densified by spark plasma sintering (SPS) at 1150 °C. During SPS processing, the effects of the heating rate were examined on microstructure and transparency. With decreasing heating rate, the grain size and the residual porosity decreased, while the transparency increased. At a heating rate of 2 °C/min, the grain size was 0.29 μm, and the in-line transmission was 46% for a wavelength of 640 nm. The mechanisms for the fine microstructure and low porosity at slow heating, which are conflicting with some existing results, were explained by considering the role of defect concentration and grain-boundary diffusion during densification.     

Improvement of sensing characteristics of self‐sensing active magnetic bearings

A winding‐current interference model of self‐sensing magnetic bearings (AMBs) and an improvement technique of position‐sensing characteristics are proposed. In the self‐sensing AMB systems, the electromagnets work not only as actuators suspending the rotor but also as position sensors. The self‐sensing position signal, however, includes errors because of nonlinearity of the magnetic circuits. In the proposed model, the current is directly transmitted to the self‐sensing position signal. This transmission means degradation of the self‐sensing characteristics. This winding‐current interference to the self‐sensing signal is reduced by the proposed compensation method. The characteristics of the proposed self‐sensing method agree well with a reference sensor signal up to over 1 kHz. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 70– 77, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20732 Copyright © 2004 Wiley Periodicals, Inc.     

Photo‐reductive fading of disperse azo dyes on nylon substrate: thermochemical analyses of reactions of photo‐induced radicals using the semiempirical molecular orbital method†

When the excited triplet states of disperse azo dyes with nitro groups abstract hydrogen to generate hydrazinyl (from azo groups) and nitrosyl hydroxide radicals (from nitro groups), both the radicals as H‐acceptors carry out azo scission, conversion to nitrogen dioxide via disproportionation reactions and self‐decomposition via rearrangement. A kinetic equation was formulated by the sum of these reactions, which describes the initial rates (K_PA) of reductive fading. The K_PA values were controlled by the rate constants of the reactions of hydrazinyl and nitrosyl hydroxide radicals as H‐acceptors, which were estimated by thermochemical analyses of the reactants, intermediates and end products using the semiempirical molecular orbital PM5 method, and by the concentrations of the reactants: H‐acceptors and H‐donors. The K_PA values observed for 12 dyes were explained semi‐quantitatively by multiple routes of reactions depending upon to what extent each radical reaction was thermochemically favoured.