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.     

Non-linear current–voltage characteristics related to native defects in SrTiO3 and ZnO bicrystals

SrTiO₃ and ZnO bicrystals with various types of boundaries were fabricated in order to examine their current–voltage characteristics across single grain boundaries. Their grain boundary structures were also investigated by high-resolution transmission electron microscopy. In Nb-doped SrTiO₃, electron transport behaviors depend on the type of boundaries. Random type boundaries exhibit highly non-linear current–voltage characteristics, while low angle boundaries show a slight non-linearity. On the contrary, undoped ZnO does not exhibit non-linear current–voltage characteristics in any type of boundaries including random ones. It is suggested that the differences observed in current–voltage properties between the two systems are mainly due to the difference in the accumulation behavior of acceptor-like native defects at grain boundaries. A clear non-linearity is obtained by means of Co-doping even for the highly coherent Σ1 boundary in a ZnO bicrystal. This is considered to result from the production of acceptor-like native defects by Co-doping.     

Preparation of micrometer‐sized,monodisperse, magnetic polymer particles

Micrometer‐sized, monodisperse, magnetic composite particles were prepared by heating micrometer‐sized, monodisperse, hollow polystyrene/polydivinylbenzene composite polymer particles at 200°C for 4 h (particles had been dipped in pentacarbonyliron) and then washed in 12 N HCl and water. The hollow polymer particles were produced by seeded polymerization by the dynamic swelling method that was proposed by authors. The magnetic composite particles contained Fe₃O₄, the content of which was 49% based on total weight, and were attracted easily in water by a 1650 G magnet. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 428–433, 2003     

Microscopic fatigue processes in a plain-weave glass-fibre composite

This paper focuses on the microscopic damage and progressive failure of a composite reinforced by plain-weave glass cloth under tensile fatigue loading. The fatigue process was divided into three stages like that of multi-directional laminates. It was found that the internal damage at each stage (matrix cracks, debonds in the weft, successive debonds in the warp and ‘metadelaminations’ between warps and wefts) occurred near the cross-over point of the fabric. The modulus decay mechanism was explained by considering the progression of this internal damage. From the end of the first stage to the beginning of the middle stage, a characteristic damage state (CDS) (called a ‘meta-CDS’) was observed. It was found that woven composites have a unit area of damage accumulation (called a ‘unit cell’) and the damage of each unit cell and its distribution control the total fatigue damage of the material.     

Analysis of an Electromagnetic Field Created by Line Current Using Constrained Interpolation Profile Method

Development of accurate schemes is a technical issue related to calculation of electromagnetic fields. This study uses constrained interpolation profile (CIP) method to analyze electromagnetic fields created by line current. This is a novel method proposed by Yabe. Comparison of results obtained using finite difference time domain (FDTD) analysis and CIP analysis indicates that CIP analysis provides higher accuracy using identical discretization. In addition, given the same level of accuracy, CIP analysis requires less memory and less calculation time     

Mortality of chromium plating workers in Japan--a 16-year follow-up study

Opportunistic infections are common and major causes of morbidity in patients with AIDS. Endemic mycoses pose serious risks for patients in certain parts of the world. Histoplasmosis occurs in 2-5% of patients with AIDS in the Ohio and Mississippi River valleys of the United States and in over 25% of patients from a few cities. Antigen testing has become a highly useful method for diagnosing histoplasmosis rapidly, evaluating the response to treatment and diagnosing relapse. Treatment with amphotericin B or itraconazole is effective (90% or higher) if the patient is not seriously ill at the time of diagnosis but the mortality approaches 50% for those with multiorgan failure. Itraconazole blood levels should be monitored and drugs that impair the absorption or accelerate the metabolism of itraconazole should be avoided. Prophylaxis with itraconazole may be appropriate in areas with an incidence of histoplasmosis. A recently completed study in cities which have unusually high rates of histoplasmosis will provide greater insight into the role of prophylactic antifungal therapy.     

Preparation of γ-alumina thin membrane by sol-gel processing and its characterization by gas permeation

-alumina porous membranes without pinholes or cracks were prepared by the sol-gel process. The boehmite sol obtained from hydrolysation of aluminium isopropoxide was applied to the inner surface of a porous supporting tube by a dipping procedure. The effects of sol concentration and the repetition number of dipping-drying-firing procedure on the membrane performance were investigated by scanning electron microscopy, X-ray diffraction and the Brunauer-Emmett-Teller method in connection with the micro-structure of the membrane. Gas permeation measurements were also conducted. The gas permeation through the thin membranes is well explained by Knudsen's flow, indicating the pores are controlled finely and homogeneously.     

Vapor phase hydroformylation of ethene over Co/SiO2 promoted by noble metals: dynamic in situ diffuse reflectance FT-IR study of surface species

An in situ diffuse reflectance FT-IR technique was employed to investigate the active surface species and the reaction mechanism of the oxygenate formation in the vapor phase hydroformylation of ethene on Co/SiO₂ promoted with various noble metals such as Ir, Rh, Pt, Re, Ru, and Pd. Co(A)/SiO₂ and Ir(CO)/SiO₂ which were derived from cobalt(II) acetate and Ir₄(CO)₁₂, respectively, were quite inactive in the reaction, and showed only quite small peaks of adsorbed CO under the conditions of 1.1 MPa of C₂H₄/CO/H₂ at 298 K. In contrast, Co(A)-Ir(CO)/SiO₂, which were very active in the reaction, exhibited strong absorption bands of linear and bridged CO species. At 423–463 K, propanal adsorbed on the catalyst and acyl species which is suggested as the intermediate for the formation of propanal were also observed on this catalyst. By exposing CO preadsorbed on this catalyst to C₂H₄/H₂ at 289 K and 0.1 MPa, the intensity of the linear CO band decreased, and the bands of propanal and acyl species emerged simultaneously, whereas that of the bridged CO band remained constant after the initial drop. These results suggested that the oxygenates are formed via the CO insertion into adsorbed ethyl species, and linear CO species plays a major role in the CO insertion on these noble metal-promoted cobalt catalysts.