System Availability and Optimum Spare Units

The steady-state availability of a repairable system with cold standbys and nonzero replacement time is maximized under constraints of total cost and total weight. Likewise the cost can be minimized under constraints of steady-state availability and total weight. A new, more efficient algorithm is used for the constrained optimization. The problem is formulated as a nonlinear integer programming problem. Since the objective functions are monotone, it is easy to obtain optimal solutions. These new algorithms are natural extensions of the Lawler-Bell algorithm. Availability is adjusted by the number of spares allowed. Other measures of system goodness are considered, viz, failure rate, weight, price, mean repair time, mean repair cost, mean replacement time, and mean replacement cost of a unit.     

Physicochemical properties of monosodium glutamate-compounded tapioca starch exceeds those of simple heat-moisture treated starch

Monosodium glutamate (GluNa)-compounded starch was prepared by heat-moisture treating a mixture of tapioca starch and GluNa. GluNa-compounded starch exhibited a higher gelatinization temperature and reduced swelling and solubility, essentially lower hardness of the granule center, and paste viscosity than those of the heat-moisture treated tapioca starch and the untreated starch. However, its appearance, unit chain length distribution, and α-amylase digestibility were similar to those of the heat-moisture treated tapioca. It is thus concluded that GluNa compounding is useful for providing a unique type of starch that possesses a less swollen and viscous texture than that produced with simple heat-moisture treatment.     

Short communication: Temporal changes in the skin morphology of dairy cows during the periparturient period

Management of dairy cow productivity requires monitoring of their nutritional status by visual observation. It has been suggested that changes in hair coat appearance are among the indicators of nutritional state in dairy cows. Temporal changes in the skin morphology in cows, however, have not been reported. In this study, we examined the changes in the skin of dairy cows that occur during the peripartum period. Seven pluriparous cows were used. Skin samples were collected at 28 d before the due date and 28 d and 56 d after calving for morphological examination. Hair follicle width was 108.8 ± 5.9 µm (±SD) in the dry period, 95.5 ± 5.5 µm at 28 d after calving, and 104.2 ± 5.3 µm at 56 d postpartum. The percentages of anagen hair follicles during these 3 periods were 41.4 ± 3.4, 18.5 ± 3.4, and 32.3 ± 3.3%, respectively. The corresponding sebaceous gland sizes were 8,362.0 ± 707.6, 7,800.0 ± 831.4, and 9,186.8 ± 962.6 µm², respectively. Hair follicle width was positively correlated with percentage of anagen hair follicles. The thickness of epidermal and proliferation rate of epidermal cell were also correlated. However, the hair follicle width, sebaceous gland size and cell proliferation rate, and thickness and proliferation rate of epidermal cells did not show any marked changes.     

Reconstruction of cartilage tissue using scaffold-free organoid culture technique

We applied the scaffold-free culture method to chondrocytes and attempted to reconstitute articular cartilage grafts. Primary rat costal chondrocytes were immobilized into hollow fibers by centrifugation at a density of 3 x 10(8) cells/cm(3) to induce the formation of cylindrical-shaped multicellular aggregates (organoids) and cultured for one month. The organoids were evaluated by histological and gene expression analyses. Chondrocytes formed cylindrical organoids in hollow fibers (HFs). Histochemical analysis revealed the accumulation of a cartilage extracellular matrix (collagen and proteoglycan) around cells in the lumen of HFs with culture time, forming a low-cellular-density tissue similar to native cartilage by day 28. Furthermore, in contrast to that in traditional monolayer culture, the organoid maintained the gene expression of the cartilage extracellular matrix (type II collagen, aggrecan) for one month of culture. In conclusion, our organoid formation method was effective in producing a cartilage-like tissue. This result suggests that the technique may be applicable to the development of an articular cartilage graft.     

Analysis of multiple indicator dilution curves for estimation of renal tubular transport parameters

A model is developed to estimate the renal tubular secretory parameters by the multiple indicator dilution (MID) technique. The model allows the calculation of influx (from plasma space to tubular cell), efflux (from tubular cell to plasma space) and sequestration (from tubular cell to luminal side) rate constants. A program using the MID-statistical analysis with least squares fitting (SALS) system for the estimation of these parameters is presented. A trapezoid rule and a non-linear least squares regression were used to carry out definite integrals of cubic spline function and least squares fitting, respectively. The system presented seems to be useful for the precise and rapid estimation of the tubular secretory rate constants.     

Magnetic and insulating properties of electrical steel with a new insulating coating

New inorganic-organic coatings for nonoriented electrical sheets have been developed. Smooth and dull sheets having surface roughnesses of 0.18 μm. H root mean square (rms) and 0.75 μm. H rms, respectively, were coated with different weights of a bichromate-emulsion resin solution. Another sheet having a surface roughness of 0.18 μm. H rms was treated with a bichromate-emulsion resin solution containing a dispersed polyethylene resin powder to provide surface roughness. Results indicated that this third sheet exhibits a higher lamination factor and surface resistivity than the coated sheet whose surface roughness is provided by the dullness of the sheet itself. Moreover, it has a lower core loss and requires less ac exciting current when used in welded motor cores at given thicknesses. When weldability is not a factor, then the smooth sheet having a surface roughness of 0.18 μm. H rms and treated with the inorganic-organic coating is the most suitable: it has the highest lamination factor, the least amount of core loss, and requires the least amount of ac exciting current.     

Improvement of bitumen-waste product in leachability—Leachability of bitumen product containing BWR's evaporator concentrate

The method has been developed to improve the bitumen product which incorporates an evaporator concentrate from a BWR, with respect to the swelling and leaching. The leachability of the product has been measured by the method recommended by the IAEA. The swelling of the product is successfully prevented by the addition of calcium chloride. The specimen containing the waste up to Wa/B (Weight ratio of Na₂SO₄ + CaCl₂ and bitumen) = 60:40 shows no pronounced swelling, when it is immersed in water. The cumulative fractions of ¹³⁷Cs and ⁶⁰Co leached from a specimen which does not contain CaCl₂ are 0.65 and 0.2 at the leaching time of 30 days. On the hand, the corresponding value at 100 days for the specimen with calcium chloride addition is 5 × 10^?4 for ¹³⁷Cs and 1 × 10^?4 for ⁶⁰Co. The coating of the specimen surface with a fresh bitumen (5 mm thickness) reduces the leachability further. These results indicate that this method is effective to improve the bitumen product incorporating BWR's evaporator concentrate.