稻谷壳流化床的燃烧特性

介绍了稻谷壳的物理化学特性及热重试验结果，与煤燃烧特性进行对比，阐述了稻谷壳燃烧过程中，挥发分与焦炭分阶段燃烧的概念；并通过燃烧试验提出了独特的以纯稻谷壳流态化燃烧方式为主的组合燃烧方式，为纯稻谷壳流态化燃烧锅炉设计和运行提供了理论依据。     

Malarial parasites complete sporogony in axenic mosquitoes

Summary To obtain sporogonic stages of malaria free from microbial contaminants for in vitro studies,Anopheles stephensi were reared under sterile conditions using a mosquito cell line as larval food. The adult females, kept in sterile humidified containers and allowed to engorge on parasitemic hamsters, supported the sporogonic development of the rodent malarial parasitePlasmodium berghei. In 10 experiments, the proportion of infected mosquitoes varied from 0 to 92%, and the geometric mean number of oocysts per female mosquito from 2.5 to 58,6, with a range of 1 to 548. The average number of salivary gland sporozoites per infected mosquito was determined by direct sporozoite counts in the pooled homogenate of the thoraces of all female mosquitoes. In five experiments, it varied from 2.7×10³ to 9.0×10³. The sterile sporozoites, harvested on day 19 or 20 after the infective blood meal, were as infective for rodents as nonsterile ones.Supported in part by Public Health Service research grant AI 18345 from the National Institute of Allergy and Infectious Diseases, by a grant from the Agency of International Development DSPE-5542-G-SS-3042-00, and by a Charles and Johanna Busch award.     

A family of mammalian Na+-dependent L-ascorbic acid transporters.

Vitamin C (L-ascorbic acid) is essential for many enzymatic reactions, in which it serves to maintain prosthetic metal ions in their reduced forms (for example, Fe2+, Cu+), and for scavenging free radicals in order to protect tissues from oxidative damage. The facilitative sugar transporters of the GLUT type can transport the oxidized form of the vitamin, dehydroascorbic acid, but these transporters are unlikely to allow significant physiological amounts of vitamin C to be taken up in the presence of normal glucose concentrations, because the vitamin is present in plasma essentially only in its reduced form. Here we describe the isolation of two L-ascorbic acid transporters, SVCT1 and SVCT2, from rat complementary DNA libraries, as the first step in investigating the importance of L-ascorbic acid transport in regulating the supply and metabolism of vitamin C. We find that SVCT1 and SVCT2 each mediate concentrative, high-affinity L-ascorbic acid transport that is stereospecific and is driven by the Na+ electrochemical gradient. Despite their close sequence homology and similar functions, the two isoforms of the transporter are discretely distributed: SVCT1 is mainly confined to epithelial systems (intestine, kidney, liver), whereas SVCT2 serves a host of metabolically active cells and specialized tissues in the brain, eye and other organs.     

Aggregates of acetylcholinesterase induced by acetylcholine receptor-aggregating factor

Basal lamina-rich extracts of Torpedo californica electric organ contain a factor that causes acetylcholine receptors (AChRs) on cultured myotubes to aggregate into patches. Our previous studies have indicated that the active component of these extracts is similar to the molecules in the basal lamina which direct the aggregation of AChRs in the muscle fibre plasma membrane at regenerating neuromuscular junctions in vivo. Because it can be obtained in large amounts and assayed in controlled conditions in cell culture, the AChR-aggregating factor from electric organ may be especially useful for examining in detail how the postsynaptic apparatus of regenerating muscle is assembled. Here we demonstrate that the electric organ factor causes not only the formation of AChR aggregates on cultured myotubes, but also the formation of patches of acetylcholinesterase (AChE). This finding, together with the observation that basal lamina directs the formation of both AChR and AChE aggregates at regenerating neuromuscular junctions in vivo, leads us to hypothesize that a single component of the synaptic basal lamina causes the formation of both these synaptic specializations on regenerating myofibres.     

Identification of angiogenic activity and the cloning and expression of platelet-derived endothelial cell growth factor

Cloning and sequencing of the complementary DNA for platelet-derived endothelial cell growth factor indicates that it is a novel factor distinct from previously characterized proteins. The factor, a protein with a relative molecular mass of about 45,000, stimulates endothelial cell growth and chemotaxis in vitro and angiogenesis in vivo.     

Isolation and characterization of hemagglutinins from the sponge Dysidea herbacea

The sponge Dysidea herbacea (Keller) was found to possess hemagglutinins. The major component, DHA-I, is a protein with a mol. wt of 26,000, which dissociates into subunits of equal size (14,000). It contains large amounts of glutamic acid and aspartic acid residues, but no half-cystine, methionine or histidine residues. DHA-I reacted with rabbit and human AB0 erythrocytes. D-galactose and lactose were effective inhibitors of DHA-I. The sponge also contained a minor component(s) which reacted preferentially with rabbit erythrocytes but not with human AB0 erythrocytes.