Mean molal activity coefficients of aqueous scandium chloride, nitrate, bromide and perchlorate solutions at 25.0°

The mean molal activity coefficients of aqueous scandium chloride, nitrate, bromide and perchlorate solutions were determined at 25.0° for dilute to saturated concentrations, together with the activities of water. In the dilute solutions of scandium halides, the activity coefficients were obtained from electromotive force measurements on galvanic cells, and the osmotic coefficients of all four solutions above 0.1 mol kg⁻¹ were determined from the isopiestic measurements. Least-squares equations were fitted to these coefficients, which were then used to calculate the mean molal activity coefficients and water activities. The relationships between these results and the corresponding activity data for other rare earth salts, and to the cation hydration and ionic interactions, are discussed. The results on scandium perchlorate solutions suggested that the inner-sphere hydration number of tervalent scandium ion may be seven.     

EXERGETIC EVALUATION OF GAS TURBINE COGENERATION SYSTEMS FOR DISTRICT HEATING AND COOLING

A cogeneration system (CGS) generating both power and heat for district heating and cooling is required to be able to cope efficiently with its heat demand change. In this paper, two types of gas turbine CGSs were investigated: (1) a CGS using a dual fluid cycle; and (2) a CGS using a combined cycle. Exergy flows at various points of each CGS have been evaluated when its heat demand is changed. The following have been shown through simulation studies: (a) the higher the heat supply ratio, the higher the exergetic efficiency of the dual fluid cycle CGS; (b) the lower the heat supply ratio, the higher the exergetic efficiency of the combined cycle CGS; and (c) the highest exergetic efficiency of the dual fluid cycle CGS at the maximum heat supply operation is higher than that of the combined cycle CGS; and the exergetic efficiency of the combined cycle CGS at the minimum heat supply operation is higher than that of the dual fluid cycle CGS. A simple criterion has also been derived for determining which type of CGS has higher average exergetic efficiency for a specific district when its heat demand characteristics are known. © 1997 by John Wiley & Sons, Ltd.     

An economic evaluation of recombinant bovine somatotropin approval in Japan

A comprehensive econometric model was developed to evaluate potential impacts of recombinant bovine somatotropin (rbST) approval in Japan. Three novel features of the analyses include 1) investigation of impact of rbST on herd-size structure, 2) determination of economic feasibilities of rbST adoption by herd size, and 3) evaluation of policies to mitigate negative effects of rbST approval. Simulation analysis was conducted over a 10-yr projected period assuming rbST was approved in Japan in 2001. Nine hypothetical scenarios were simulated to examine sensitivity of simulation results. Simulation results indicate that rbST approval would accelerate structural change in Japan's dairy industry toward fewer, larger farms. Negative effects of rbST on farm income are projected to be more severe for smaller farms, because of higher costs, lower profit-earning ability, lower milk yields, and lower adoption rates of rbST. Larger farms benefit from rbST adoption if milk demand is maintained. However, if concerns about rbST induce significant milk demand decreases, even the largest farms' income and cow numbers will decrease. Thus, Japan's dairy industry could be caught in a double downward spiral of declining milk prices and production. Assuming rbST is approved, small farms would benefit by using the technology, but they fare best if rbST is not approved. Two policies could be effective in mitigating possible farm income losses. First, lost farm income can be offset if dairy cooperatives can exercise greater market power to control fluid milk marketings. Second, because generic milk advertising has positive effects on both milk demand and farm income, increasing check-off rates to fund more advertising could ease farm income losses.     

Monitoring biofilm development in a microfluidic device using modified confocal reflection microscopy

The feasibility of a method to monitor biofilm development non-destructively in a microfluidic device was addressed. Here, we report that biofilm growth could be non-destructively monitored by an image analysis technique based on modification of confocal reflection microscopy.     

Improvement in the remaining activity of freeze-dried xanthine oxidase with the addition of a disaccharide–polymer mixture

In order to improve the remaining activity of a practically important freeze-dried enzyme, xanthine oxidase (XOD), the effects of disaccharide (sucrose and trehalose), polymer (bovine serum albumin: BSA and dextran) and a mixture of them on the loss of XOD activity during freeze-drying and subsequent storage were investigated. All samples were amorphous solids and their glass transition temperatures (T_g) were evaluated by using differential scanning calorimetry. Although dextran showed no stabilizing effect on the freeze-dried XOD, the others protected XOD from the activity loss during freeze-drying to a certain extent. It was found that the mixture of disaccharide (sucrose or trehalose) and BSA improved the XOD activity synergistically. The XOD activity of the samples decreased gradually during storage at a temperature range of between 25 and 60 °C. Samples stored at temperatures below the T_g showed a lower loss of XOD activity than those stored at just the T_g.     

Phase transition and hydrogenation properties of Ce2Ni7-type Pr2Co7 during the hydrogen absorption process

The crystal structure and hydrogenation properties of Pr₂Co₇ with a Ce₂Ni₇-type structure were investigated by X-ray diffraction (XRD) and observation of the pressure–composition (PC) isotherms. The reversible hydrogen capacity reached 0.8 H/M, and two plateaus were observed in the absorption–desorption process. The two observed hydride phases, Pr₂Co₇H_2.7 and Pr₂Co₇H_7.2, were determined to have hexagonal (space group: P6₃/mmc) and orthorhombic (space group: Pbcn) crystal structures, respectively. The crystal structure transformed in the order of hexagonal with a Ce₂Ni₇-type structure (original alloy) → same Ce₂Ni₇-type structure (Pr₂Co₇H_2.7) → orthorhombic (Pr₂Co₇H_7.2). The crystal lattice of the Pr₂Co₇H_2.7 underwent anisotropic expansion along the c-axis of the original alloy, whereas that of Pr₂Co₇H_7.2 exhibited isotropic expansion. The full width at half maximum (FWHM) values for the original alloy and hydride phases during the hydrogen absorption–desorption process were evaluated based on the XRD data. The FWHM values for the main peaks decreased as the hydrogen content increased during the absorption process, indicating that the number of lattice defects did not increase upon hydrogenation. The plateau pressures during the absorption process of the second cycle were the same as those of the first cycle, which also suggests that there were no lattice defects.     

Isolation and characterization of protein fractions from deoiled rice bran

Rice bran contains underutilised protein materials. Sequential extraction of rice bran protein (RBP) from defatted rice bran was conducted based on the differences in their solubility. Three extraction methods were investigated. Method 1 involved the isoelectric and acetone precipitation using water, 50 g kg⁻¹ NaCl, 0.02 mol L⁻¹ NaOH and 70% ethanol as extracting solvents for albumin (pH 4.1), globulin (pH 4.3), glutelin (pH 4.8) and prolamin, respectively. Method 2 adopted dialysis and sequential extraction was carried out with 20 g kg⁻¹ NaCl, 70% ethanol, 0.1 mol L⁻¹ acetic acid and 0.1 mol L⁻¹ NaOH solution as extracting solvents. Method 3 combined dialysis, isoelectric and acetone precipitation for the extraction. Based on the yields and data obtained from sodium dodecyl sulphate polyacrylamide gel electrophoresis, size-exclusion chromatography and differential scanning calorimetry, method 3 was chosen for the isolation and characterization of RBPs. Rice bran protein fraction (RBPF)—albumin, globulin, glutelin and prolamin were obtained in good yields. Denaturation temperature and enthalpy values of denaturation of RBPF vary. Highest phytate content was found in albumin and lowest in prolamin. The highest antioxidative and hemagglutinating activities were observed in albumin.     

Changes in calpain and calpastatin activities of osmotically dehydrated bovine muscle during storage after treatment with calcium

Calpain and calpastatin activities were investigated in calcium-treated beef after osmotic dehydration. Dehydrated beef was soaked in 150 mM calcium chloride solution for 3 h, and then stored for 48 h at 3-4 °C. The untreated sample (control) was soaked in deionized water for 3 h instead of calcium chloride solution, after osmotic dehydration. The increase and decrease in the relative activity of crude calpain were observed in the untreated and the calcium-treated meat, respectively, during the storage. When the crude calpains were subjected to DEAE-Sephacel column chromatography, it was found that μ-calpain activity decreased rapidly during the storage in the untreated meat, whereas there was almost no change in the activity of m-calpain during the storage. The decrease of calpastatin activity was moderate compared with the decrease of μ-calpain activity. In the calcium chloride-treated meat, however, no μ-calpain nor calpastatin activities was detectable after 48 h at cold-room temperature, and m-calpain activity after 48 h had decreased to 6.1% of its activity immediately after thawing. It was concluded that 150 mM calcium chloride treatment after osmotic dehydration was sufficient to introduce calcium ions into the meat. In the presence of sufficient calcium, autolysis of calpains and proteolytic degradation of calpastatin, which eventually related to the rate of decrease in calpain and calpastatin activities, clearly seem to be related to a decrease in meat toughness.     

Dioxin-like and transthyretin-binding compounds in indoor dusts collected from Japan: average daily dose and possible implications for children

Many researchers are increasingly interested in human exposure to house dust containing household compounds such as polybrominated diphenylethers (PBDEs). Nevertheless, no investigations have addressed the endocrine-disrupting potencies of compounds contained in indoor dust. This study specifically addresses endocrine-disrupting potencies such as dioxin-like activity and human transthyretin (TTR)-binding potencies. Using in vitro bioassays, we investigated these activity levels in indoor dusts. We performed exposure assessments of active compounds that are contained in house dust for subsequent evaluation of house dusts' risks to humans. Dioxin-like and TTR-binding activities in sulfuric acid treatment extracts of house and office dust were investigated using Dioxin-Responsive Chemical-Activated LUciferase gene eXpression assay (DR-CALUX) and TTR-binding assay (in vitro competitive human TTR-binding assay). Dioxin-like activities in indoor dust were 38-1400 pg CALUX-TEQ (2,3,7,8-TCDD equivalent)/g (median 160 pg CALUX-TEQ/g) and TTR-binding potencies were 300-5000 pmol T4EQ (thyroxine (T4) equivalent)/g (median 1000 pmol T4EQ/g), which are higher values than those in other environmental samples, e.g., contaminated sediments. These exposure results suggest that children might be affected by both dioxin-like compounds and TTR-binding compounds via house dust. When the ingestion rate, CALUX-TEQ, and T4EQ for house dust are high, thyroid hormone homeostasis in children may be disrupted.