The removal of inhaled 239Pu from beagle dogs by bronchopulmonary lavage and chelation therapy

The presence of C3 receptor sites on the cell surfaces of WI-38 fibroblasts was reported in a previous paper. Here the effect of dexamethasone sodium sulfate of C3 receptor site function was studied. The incubation of WI-38 fibroblasts with dexamethasone sodium sulfate produces the biphasic mode of action, i.e., the growth-stimulating phase with low doses (90--230 mug/ml) and the growth-inhibiting phase with high doses (450--900 mug/ml). The function of C3 receptor sites on WI-38 fibroblasts seems to be very stable and cannot be suppressed by the pretreatment of WI-38 fibroblasts with dexamethasone in high concentrations, where the cell growth is inhibited.     

Mycobacterium smegmatis fatty acid synthetase. Polysaccharide stimulation of the rate-limiting step

An initial activity burst lasting 5 to 10 s is observed for both de novo synthesis with acetyl-CoA as primer and for elongation of palmitoyl-CoA catalyzed by the multienzyme complex fatty acid synthetase from Mycobacterium smegmatis. After the initial burst, synthetase activity slows at least 6-fold to the steady state rate. The size of the initial burst is proportional to the amount of synthetase protein and corresponds to the synthesis of a small number C three to five) of C24 or C26 acyl chains per mol of enzyme. During the initial burst, C24, C26 acyl enzyme is formed and can be isolated by ammonium sulfate precipitation. On incubation with CoA, enzyme-bound acyl chains undergo transacylation to form the corresponding CoA derivatives. Diffusion of C24-CoA and C26-CoA from the enzyme is slow and rate-limiting for overall fatty acid synthesis. Mycobacterial polysaccharides markedly accelerate this rate-determining step but bovine serum albumin does not. This facilitation of product diffusion accounts for the large stimulation of de novo synthesis and of elongation of mycobacterial polysaccharide. It is also shown that the high apparent Km for acetyl-CoA (approximately 400 micrometer) in the steady state reflects the substrate concentration required to shift the product pattern in favor of shorter chain fatty acids (C16,C18). These conditions circumvent the slow, rate-limiting diffusion of C24-CoA and C26-CoA.     

DERIVING PLACE-SPECIFIC MEASURES OF THE RENTAL HOUSING CRISIS FROM THE 1980 CENSUS: AN APPLICATION FROM TEXAS

The argument is advanced that rental affordability problems are the key symptom of the rental housing crisis. These problems may be measured by the rent-to-income ratio as reported by the 1980 census for five different income groups. Of special significance is that these data are available in a standardized form for every county, city and census tract in the nation. To demonstrate the use of these data, a rent burden indicator is constructed from these data and then applied to all counties in Texas with at least 100,000 population. One county, Travis, stands out with a particularly high incidence of rent burden, and this incidence is only slightly reduced when the rent burden indicator is adjusted to a standardized income distribution. This provides clear evidence of an unusually severe rental housing crisis.     

Mycobacterium smegmatis fatty acid synthetase. Long chain transacylase chain length specificity

Long chain transacylase activity, acyl-CoA + enzyme in equilibrium acyl-enzyme + CoA, catalyzed by the multienzyme complex fatty acid synthetase from Mycobacterium smegmatis was measured by exchange of radioactive coenzyme A into even numbered fatty acyl-CoA substrates 14 to 24 carbon atoms long. This transacylase activity decreases sharply with increasing chain length. It is suggested that C24 transacylation may be rate-limiting in de novo fatty acid synthesis catalyzed by the myocobacterial system. Mycobacterial polysaccharides stimulate the rate of transacylation, and this enhancement becomes more marked as the chain length of the substrate increases. The magnitude of the effect is similar to polysaccharide stimulation of overall synthetase activity. It is therefore proposed that terminal transacylation is the specific and perhaps only partial reaction catalyzed by the M. smegmatis fatty acid synthetase which is facilitated by polysaccharide. The product distribution of the synthetase is distinctly bimodal, with peaks for acyl chains 16 and 24 carbon atoms long. A scheme based on nonoverlapping unimodal chain length specificities for the rates of two activities, elongation and terminal transacylation, is offered to explain this bimodal distribution.     

Sulfonated carbon black-based composite membranes for fuel cell applications

Two different commercial grade carbon black samples, Cabot Regal 400R (C1) and Cabot Mogul L (C2), were sulfonated with diazonium salt of sulfanilic acid. The resultant sulfonated carbon black samples (S–C) were characterized by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Composite membranes were then prepared using S–C as fillers and sulfonated poly(ether ether ketone) (SPEEK) as polymer matrix with three different sulfonation degrees (DS = 60, 70 and 82%). Structure and properties of the composite membranes were characterized by FTIR, TGA, scanning electron microscopy, proton conduction, water uptake, ion exchange capacity and chemical stability. Incorporation of S–C particles above 0· 25 wt% caused decrease in chemical stability. Pristine and composite membranes prepared from SPEEK82 decomposed completely in $\boldsymbol{<}$ 1 h, which is undesirable for fuel cell applications. SPEEK60 membrane having wt% of 0·25–0· 5 with S–C particles led to higher proton conductivity than that of pristine membrane. No positive effect was observed on the properties of the composite membranes with the addition of S–C particles at high concentrations due to the agglomeration problems and decrease in the content of conductive polymer matrix.     

铝源溶解度和铁含量对FeAlPO-5分子筛结构和形貌的影响

以异丙醇铝为铝源,通过完全溶解或部分溶解制备凝胶,利用水热合成法制备系列不同铁含量的FeAlPO-5分子筛,通过XRD、IR和SEM等手段对合成的样品进行表征,结果表明, FeAlPO-5分子筛的结构和形貌受铝源溶解度和铁含量的影响。铝源完全溶解后,添加其他试剂合成的FeAlPO-5分子筛易出现密鳞石英相。铁的过量加入也使FeAlPO-5从AFI结构部分转变为密鳞石英相。     

清洗方法对鲜切山药贮藏效果的影响

采用不同浓度的次氯酸钠、双氧水和柠檬酸对鲜切山药进行处理,通过测定鲜切山药储藏期间的菌落总数、丙二醛含量、失重率以及感官品质来衡量清洗效果。结果表明:次氯酸钠处理可以明显降低鲜切山药的菌落总数,但浓度过高会破坏山药的内部组织,不利于其储藏;0.6%的次氯酸钠溶液处理效果较佳,双氧水次之,柠檬酸最差。     

无卤阻燃PC/ABS的制备及燃烧性能

以齐聚磷酸酯(BDP)作为添加型阻燃剂制备了阻燃PC/ABS塑料合金,采用锥形量热仪(CONE)、扫描电镜(SEM)及热裂解-气相/质谱法(Py-GC/MS)等对材料的燃烧性能和阻燃机理进行了研究.结果表明,阻燃剂BDP对PC/ABS有良好的阻燃效果;BDP的加入使PC/ABS燃烧残留物上产生大量的致密微孔,同时由Py-GC/MS分析表明BDP的加入降低了PC/ABS可燃性降解产物的生成,裂解产物中含有三苯基磷酸酯(TPP),说明BDP在塑料合金降解过程中分解生成TPP发挥阻燃作用.