Environmental effects on bamboo-glass/polypropylene hybrid composites

The effects of environmental aging and accelerated aging on tensile and flexural behavior of bamboo fiber reinforced polypropylene composite (BFRP) and bamboo-glass fiber reinforced polypropylene hybrid composite (BGRP), all with a 30% (by mass) fiber content, were studied by exposing the samples in water at 25°C for up to 1600 h and at 75°C for up to 600 h. Reduction in tensile strength for BFRP and BGRP was 12.2% and 7.5%, respectively, after aging at 25°C for about 1200 h. Tensile and flexural strength of BFRP and BGRP were reduced by 32%, 11.7%, and 27%, 7.5% respectively, after aging at 75°C for 600 h. While the strengths of the bamboo fiber reinforced composites reduce with sorption time and temperature, the environmental degradation process can be delayed by adding a small amount of glass fiber. Moisture sorption and strength reduction are further suppressed by using maleic anhydride polypropylene (MAPP) as a coupling agent in both types of composite system.     

Survival of Blastocystis hominis clones after exposure to a cytotoxic monoclonal antibody

Our previous studies have shown that monoclonal antibodies (MAbs) to Blastocystis hominis react mainly with carbohydrate epitopes, while 1 MAb (1D5) reacts specifically with a protein of 30.5 kDa. In the present study, 3 monoclonal antibodies (1D5, 1E7 and 4F7) were used in immunogold localization. 1E7 and 4F7 were found to react primarily with the surface coat, while 1D5 was plasma membrane-specific. In the presence of complement, only 1D5 exhibited a cytotoxic effect on B. hominis whereas 1E7 and 4F7 did not, suggesting that the surface coat of B. hominis could serve as an immunological barrier against host antibodies. Using a recently described agar plating method, only 1D5 exhibited significant (P < 0.01) complement-independent cytotoxicity to B. hominis, inhibiting colony growth at low concentrations. Parasites that had been exposed to 1D5 were morphologically smaller than those that were not exposed to this MAb. Colonies that grew in the presence of 1D5 were isolated and grown in liquid medium containing increasing amounts of the cytotoxic MAb. Two clones that grew well in liquid medium containing 1D5 were also able to develop into colonies in soft agar. This study has shown that the 30.5 kDa protein found on the plasma membrane of B. hominis is a functionally important protein and that not all cells within a certain population would be susceptible to the cytotoxic effects of 1D5. These findings suggest that a heterogenous population exists in continuously maintained cultures of B. hominis.     

渗透汽化分离有机混合物

采用渗透汽化进行了两类有机混合物的分离，一是从Ｃ４、Ｃ５醚后混合物中脱甲醇，二是从时、间二甲苯混合物中分离对二甲苯。以一定比例的醋酸纤维素（ＣＡ）与聚丙烯酸醋共混物的表皮分离层材料，制备渗透汽化复合膜脱除Ｃ４、Ｃ５醚后混合物中的甲醇，实验考察了料液浓度、温度等操作条件对膜分离性能的影响。结果表明共混膜兼有两类膜材料的优点，当原料中甲醇质量分数为０．４％时，膜内甲醇通量为２３０ｇ／ｍ＾２·ｈ，分离因     

Body fat and skeletal muscle mass in relation to physical disability in very old men and women of the Framingham Heart Study

BACKGROUND: Low muscle mass has been assumed to be associated with disability, but no studies confirming this association have been published. High body weight and high body mass index, both rough indicators of body fatness, have been shown to increase the risk for disability; however, the specific role of body fatness has not been studied. METHODS: The relations of skeletal muscle mass and percent body fat with self-reported physical disability were studied in 753 men and women aged 72 to 95 years. Cross-sectional data from biennial examination 22 (1992-1993) of the Framingham Heart Study were used. Body composition was assessed by dual-energy x-ray absorptiometry. Disability was scored as any versus none on a 9-item questionnaire. RESULTS: Total body and lower extremity muscle mass were not associated with disability in either men or women. However, a strong positive association between percent body fat and disability was observed. The odds ratio for disability in those in the highest tertile of body fatness was 2.69 (95% confidence interval 1.45-5.00) for women and 3.08 (1.22-7.81) for men compared to those in the lowest tertile. The increased risk could not be explained by age, education, physical activity, smoking, alcohol use, estrogen use (women only), muscle mass, and health status. Analyses restricting disability to mobility items gave similar results. CONCLUSIONS: In contrast to current assumptions, low skeletal muscle mass was not associated with self-reported physical disability. Persons with a high percent body fat had high levels of disability. Because it cannot be ruled out that persons with low skeletal muscle mass dropped out earlier in the study, prospective studies are needed to further assess the relationship between body composition and physical disability.     

UTRA/FDD RF Transceiver Requirements

Unified RF requirements are derived for an UMTS Terrestrial RadioAccess/Frequency Division Duplex (UTRA/FDD) compliant mobile transceiver. Aset of transceiver requirements are proposed with consideration to systemissues including duplex aspects. From these design-compatible requirements areproposed for each functional block in the transceiver.     

Dehydration and reduction of synthetic garnierite

The morphology of synthetic garnierite, Ni₃(OH)₄. Si₂O₅, has been studied by electron microscopy. The layer structure of the hollow garnierite needles has been made visible and the observed layer distance is in accordance with the X-ray result. Synthetic garnierite, totally dehydrated above 500° C, appears to be pseudomorphous with garnierite. Total reduction of the dehydrated product in hydrogen yields porous nickel-on-silica in which the small nickel crystallites are only partly accessible to hydrogen chemisorption.     

Adenosine triphosphate citrate lyase mediates hypocitraturia in rats

Chronic metabolic acidosis increases proximal tubular citrate uptake and metabolism. The present study addressed the effect of chronic metabolic acidosis on a cytosolic enzyme of citrate metabolism, ATP citrate lyase. Chronic metabolic acidosis caused hypocitraturia in rats and increased renal cortical ATP citrate lyase activity by 67% after 7 d. Renal cortical ATP citrate lyase protein abundance increased by 29% after 3 d and by 141% after 7 d of acid diet. No significant change in mRNA abundance could be detected. Hypokalemia, which causes only intracellular acidosis, caused hypocitraturia and increased renal cortical ATP citrate lyase activity by 28%. Conversely, the hypercitraturia of chronic alkali feeding was associated with no change in ATP citrate lyase activity. Inhibition of ATP citrate lyase with the competitive inhibitor, 4S-hydroxycitrate, significantly abated hypocitraturia and increased urinary citrate excretion fourfold in chronic metabolic acidosis and threefold in K+-depletion. In summary, the hypocitraturia of chronic metabolic acidosis is associated with an increase in ATP citrate lyase activity and protein abundance, and is partly reversed by inhibition of this enzyme. These results suggest an important role for ATP citrate lyase in proximal tubular citrate metabolism.     

Optimal taxiway repair: A set-covering approach

This paper describes an approach for optimizing a key element of air base recovery after attack—the repair of craters on linear taxiway segments. Drawing upon the concept of a minimal cut set, familiar in reliability engineering, an algebraic representation of the problem is developed in the form of a weighted set covering problem. This supplants the use of complex logical algorithms for checking the feasibility of solutions postulated during enumerative solution of the repair minimization problem. It is demonstrated that the algebraic representation leads to enhanced computational efficiency. Also, a potential advantage is suggested for the algebraic approach in facilitating extensions of repair minimization to nonlinear taxiway segments, including intersections.This research was sponsored by the Air Force Contact No. F08635-82-C-0252.