Separation of di- and tripeptides with solvent extraction and an emulsion liquid membrane

The extraction equilibria of various di- and tripeptides with di-2-ethylhexylphosphoric acid (D2EHPA) were studied at low pH values. The complex extracted to organic phase consisted of one molecule of peptide and two molecules of D2EHPA dimer. The extraction constants of the peptides correlated well with the distribution coefficients of peptides between 1-octanol and water, which is a measure of hydrophobicity. The permeation rates of peptides through an emulsion liquid membrane were examined by using D2EHPA as a carrier, Span 80 as an emulsifier and kerosene as a diluent. The rates varied considerably with peptide type, depending upon the hydrophobicity.     

Performance prediction of a hybrid‐excitation synchronous machine with axially arranged excitation poles and permanent‐magnet poles

This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033     

Explanation of impact load curve in ball impact test in relation to thermal aging

Solder joints are required to have high impact strength for use in portable electronic products. To make solder joints with high impact strength, qualitative evaluation methods of impact strength are required. Ball impact tests have been widely adopted in evaluating the impact strength of solder joints because of their easy implementation. Impact load curves obtained from ball impact tests are used as an evaluation indicator of impact strength of solder joint. However, a relation between fracture behavior and impact load curve has not yet been clarified, and an explanation of the impact load curve has not yet been provided in detail. In addition to this, detailed study about the relation between IMC layer thickness and impact strength has not been performed, although the IMC layer thickness formed at the interface would significantly affect the impact strength of the solder joint. This study aimed to explain the impact load curve in the ball impact test and to reveal the effect of the IMC layer thickness on the impact strength of the solder joint. Sn–3.0Ag–0.5Cu solder was reflowed on an electroless Ni–P plated Cu substrate (Ni–P), and a ball impact test was then carried out to evaluate the impact strength. This study found that the ball impact test is effective to evaluate the interfacial strength of solder joints. In the impact load curve, it is estimated that the solder bump keeps deforming until the interfacial crack initiates (maximum load), and the interfacial crack initiates after the maximum load and propagates along the interface between the solder and Ni–P. The suitable evaluation of impact strength became possible by measuring the correspondence relation between the deformation distance of the solder bump after fracture and the energy until maximum load and the relation between the area fraction of the residual solder on the fractured pad and the energy after maximum load. And, it is proved that the impact strength decreased with increasing aging time because the growth of the IMC layer remarkably degraded the interfacial strength of the solder joint.     

Sequestration of distasteful compounds by some pharmacophagous insects

Several pharmacophagous insects have been shown to sequester specific kairomonal substances or their derivatives in their body tissues. Turnip sawflies,Athalia rosae, visit a plant,Clerodendron trichototmum (Verbenaceae), and feed voraciously on the leaf surface. Clerodendrins were characterized as the potent phagostimulants forA. rosae adults. The insect sequesters some of the analogs and becomes extremely bitter on its body surface. Some chrysomelid leaf beetles associated with cucurbitacins were found to store high concentrations of these bitter principles in their body. South American polyphagous beetles,Diabrotica speciosa andCerotoma arcuata, are strongly arrested by root components from the cucurbit plant,Ceratosanthes hilariana, and selectively accumulate 23,24-dihydrocucurbitacin D, effectively gaining bitterness. Similarly, four species of Asian pumpkin leaf beetles belonging to the genusAulacophora were shown to sequester the same compound in body tissue as the major bitter principle. Three phenylpropanoids closely related to methyl eugenol were found to accumulate in the rectal glands of the male Oriental fruit fly,Dacus dorsalis. One of the rectal gland components, 2-allyl-4,5-dimethoxyphenol was shown to be released in the air during courtship. In all of these cases, selectively sequestered compounds strongly deterred feeding by some predators, thus serving as allomones in this context. Kairomonal and pheromonal functions linked with allomonal sequestration by pharmacophagous feeding has also been suggested.     

Characterization of germanium implanted Si1−xGex layer

Characterization of a Si_1−xGe_x layer formed by high-dose germanium implantation and subsequent solid phase epitaxy is reported. Properties of this layer are obtained from electrical measurements on diodes and transistors fabricated in this layer. Results are compared with those of the silicon control devices. It was observed that the germanium implantation created considerable defects that are difficult to eliminate with annealing. These defects result in boron deactivation in the p-type regions of the devices, giving rise to larger resistance. Optimization of the device structure and fabrication process is discussed.     

Acceleration of nonylphenol and 4-tert-octylphenol degradation in sediment by Phragmites australis and associated rhizosphere bacteria

We investigated biodegradation of technical nonylphenol (tNP) in Phragmites australis rhizosphere sediment by conducting degradation experiments using sediments spiked with tNP. Accelerated tNP removal was observed in P. australis rhizosphere sediment, whereas tNP persisted in unvegetated sediment without plants and in autoclaved sediment with sterile plants, suggesting that the accelerated tNP removal resulted largely from tNP biodegradation by rhizosphere bacteria. Three bacterial strains, Stenotrophomonas sp. strain IT-1 and Sphingobium spp. strains IT-4 and IT-5, isolated from the rhizosphere were capable of utilizing tNP and 4-tert-octylphenol as a sole carbon source via type II ipso-substitution. Oxygen from P. australis roots, by creating highly oxygenated conditions in the sediment, stimulated cell growth and the tNP-degrading activity of the three strains. Moreover, organic compounds from P. australis roots functioned as carbon and energy sources for two strains, IT-4 and IT-5, supporting cell growth and tNP-degrading activity. Thus, P. australis roots elevated the cell growth and tNP-degrading activity of the three bacterial strains, leading to accelerated tNP removal. These results demonstrate that rhizoremediation of tNP-contaminated sediments using P. australis can be an effective strategy.     

Investigation of the antiviral properties of copper iodide nanoparticles against feline calicivirus

This study demonstrated the antiviral properties of copper iodide (CuI) nanoparticles against the non-enveloped virus feline calicivirus (FCV) as a surrogate for human norovirus. The effect of CuI nanoparticles on FCV infectivity to Crandell-Rees feline kidney (CRFK) cells was elucidated. The infectivity of FCV to CRFK cells was greatly reduced by 7 orders of magnitude at 1000μgml(-1) CuI nanoparticles. At the conditions, electron spin resonance (ESR) analysis proved hydroxyl radical production in CuI nanoparticle suspension. Furthermore, amino acid oxidation in the viral capsid protein of FCV was determined by nanoflow liquid chromatography-mass spectrometric (nano LC-MS) analysis. The use of CuI nanoparticles showed extremely high antiviral activity against FCV. The high antiviral property of CuI nanoparticles was attributed to Cu(+), followed by ROS generation and subsequent capsid protein oxidation. CuI nanoparticles could be proposed as useful sources of a continuous supply of Cu(+) ions for efficient virus inactivation. Furthermore, this study brings new insights into toxic actions of copper iodide nanoparticles against viruses.     

Polysulfide reduction using sulfate-reducing bacteria in a photocatalytic hydrogen generation system

A hydrogen generation process using photocatalytic reactions has been proposed. In this process, hydrogen sulfide is a source of hydrogen and is turned into polysulfide. In order to establish the cyclic operation of a photocatalytic hydrogen generation system, it is necessary to convert polysulfide back into hydrogen sulfide with a small energy input. This paper proposes the use of sulfate-reducing bacteria (SRB) for the regeneration of hydrogen sulfide. Batch cultivation of natural source SRB samples were carried out using a culture medium containing polysulfide as the only sulfur compound source. SRB produced hydrogen sulfide from several kinds of polysulfide sources, including a photocatalytic hydrogen generation-produces solution. Production lag phase and production rate of hydrogen sulfide were affected by initial polysulfide concentration. SRB activity was inhibited at high initial polysulfide concentrations. SRB enrichment culture T2, exhibited the highest hydrogen sulfide production rate, and was able to utilize several kinds of organic matter as the electron donor. The results suggest the possibility of using large biomass sources, such as sewage sludge and the raw garbage in a hydrogen generation system. We developed speculative estimates that an SRB based hydrogen generation system is feasible.     

Comparative characterisation of dioxane-soluble lignins released by ball milling and by sheep digestion from forage grasses

Faecal soluble lignin (FSL), extracted from the faeces of sheep that received orchardgrass and timothy, were compared with 90% dioxane-soluble lignins released by ball milling (MHL) and by subsequent enzymatic hydrolysis (EHL) from the same grasses. FSL contained much less carbohydrate and esterified p-coumaric and ferulic acids than MHL and EHL. Although no considerable differences were found in the yields of vanillin and syringaldehyde produced by nitrobenzene oxidation, the molar ratio of syringaldehyde to vanillin was higher for FSL than for MHL and EHL. Such differences in chemical properties among the lignin preparations were confirmed by ¹³C-NMR spectroscopy. FSL had a lower molecular size compared with MHL and EHL. Results indicated that syringyl-rich lignin fragments with less phenolic acid esters, probably depolymerisation products of the grass lignins, were released by digestion in sheep from the forage grasses.