胆红素锶的EXAFS和FT—IR研究

以胆红素(H_2BR)为原料,合成组成为SrBR·2H_2O的胆红素锶,并进行了EXAFS研究,得知胆红素锶的第一配位层包含0和N两种原子,配位数为8,其Sr-O和Sr-N距离分别为2.60A和2.69A。比较H_2BR和SrBR·2H_2O的FT-IR光谱,根据-NH,-COOH和内酰胺等谱带变化,提供了胆红素中含氮和含氧基团与锶配位的证据,与EXAFS实验结果相互一致。     

Reduced nitrogen fixation in the glacial ocean inferred from changes in marine nitrogen and phosphorus inventories.

To explain the lower atmospheric CO2 concentrations during glacial periods, it has been suggested that the productivity of marine phytoplankton was stimulated by an increased flux of iron-bearing dust to the oceans. One component of this theory is that iron-an essential element/nutrient for nitrogen-fixing organisms-will increase the rate of marine nitrogen fixation, fuelling the growth of other marine phytoplankton and increasing CO2 uptake. Here we present data that questions this hypothesis. From a sediment core off the northwestern continental margin of Mexico, we show that denitrification and phosphorite formation-processes that occur in oxygen-deficient upwelling regions, removing respectively nitrogen and phosphorus from the ocean-declined in glacial periods, thus increasing marine inventories of nitrogen and phosphorus. But increases in phosphorus were smaller and less rapid, leading to increased N/P ratios in the oceans. Acknowledging that phytoplankton require nitrogen and phosphorus in constant proportions, the Redfield ratio, and that N/P ratios greater than the Redfield ratio are likely to suppress nitrogen fixation, we suggest therefore that marine productivity did not increase in glacial periods in response to either increased nutrient inventories or greater iron supply.     

澳大利亚新英格兰地区桉树林的群落结构特征

本文研究澳大利亚新英格兰地区开阔林的群落结构特征。结果表明其种类组成较为简单,调查的4.8公顷样地中树木层只有18种。隶属于4属4科,树木个体90％为桉树;灌木层有32种19属13科;草本层有95种20属10科。群落的垂直结构为三层:树层,灌木层和草本层;一些林段只有二层(缺灌木层),或四层(增多小树层)。优势种群的分布格局多为集群分布。非优势种群的分布格局则多为随机分布格局。种间联结现象较弱,除少数种对外,联结系数低或没有联结。种间生态位的重叠值低,反映了诸多种群的独立分布特征。在其组织结构水平上,除草本层外。物种多样性指数、群落均匀度、生态优势度均较低。反映群落的优势种明显,为种多群落类型。     

Somatic mutations affect key pathways in lung adenocarcinoma

Determining the genetic basis of cancer requires comprehensive analyses of large collections of histopathologically well-classified primary tumours. Here we report the results of a collaborative study to discover somatic mutations in 188 human lung adenocarcinomas. DNA sequencing of 623 genes with known or potential relationships to cancer revealed more than 1,000 somatic mutations across the samples. Our analysis identified 26 genes that are mutated at significantly high frequencies and thus are probably involved in carcinogenesis. The frequently mutated genes include tyrosine kinases, among them the EGFR homologue ERBB4; multiple ephrin receptor genes, notably EPHA3; vascular endothelial growth factor receptor KDR; and NTRK genes. These data provide evidence of somatic mutations in primary lung adenocarcinoma for several tumour suppressor genes involved in other cancers--including NF1, APC, RB1 and ATM--and for sequence changes in PTPRD as well as the frequently deleted gene LRP1B. The observed mutational profiles correlate with clinical features, smoking status and DNA repair defects. These results are reinforced by data integration including single nucleotide polymorphism array and gene expression array. Our findings shed further light on several important signalling pathways involved in lung adenocarcinoma, and suggest new molecular targets for treatment.     

Effect of Fabric Elongation on the Making Up of Pressure Garments

Pressure garments are widely used in Hong Kong andmany other countries for burn rehabilitation.Thesegarments are mainly made of elastic Lycra fabrics andtailor-made to individual patient's measurement toprovide an appropriate amount of skin-garment in-terface pressure for medical treatment.However,thefabric tension would be reduced due to fabric elonga-tion under prolonged period of stress,and thus theskin-garment interface pressure cannot be main-tained after repeated use of the garment.This paperaims to study the behaviour of fabric elongation of thefabrics commonly used for making pressure garmentsin U.K.and/or Hong Kong.Attempts to correct theexisting practice of drafting the pressure garments forproviding a more effective clinical treatment.     

High and low affinity transport ofL-arginine in rat brain synaptosomes

The uptake ofL-arginine into purified rat brain synaptosomes was investigated with respect to time and various concentrations ofL-[³H] arginine. Specific uptake was found to be linear with time for up to 5 min of incubation at 37°C. Electrolytes, including sodium chloride, potassium chloride, magnesium chloride and calcium chloride, inhibited uptake of 3 ML-arginine, and the inhibitory effect increased with increased electrolyte concentration under constant osmolarity. It was found thatL-arginine was transported into synaptosomes by two uptake components — a high affinity component (3.5 M) and a low affinity component (100 M). These two components were similar to the Ly⁺ system because of their extreme sensitivity to inhibition byL-lysine andL-ornithine but were distinguishable from each other by kinetic analysis of the uptake data and by their relative sensitivity to inhibition by several amino acids.     

Revision of the sesarmid crab genera Labuanium Serène and Soh, 1970, Scandarma Schubart,Liu and Cuesta, 2003 and Namlacium Serène and Soh, 1970 (Crustacea: Decapoda: Brachyura: Sesarmidae), with descriptions of four new genera and two new species

ABSTRACT

The systematics of the arboreal sesarmid crab genera Labuanium Serène and Soh, 1970 and Scandarma Schubart, Liu and Cuesta, 2003 is revised. Also included is the poorly known genus Namlacium Serène and Soh, 1970, which is morphologically similar to Labuanium and may also be arboreal in habit. The present study restricts Labuanium to its type species, L. politum (De Man, 1887), and congeners are transferred to Scandarma, Geosesarma De Man, 1892, and three new genera established herein: Circulium gen. nov., Shinobium gen. nov. and Mindanium gen. nov. Two new species of Scandarma are described from Papua New Guinea and Madagascar. Sesarma jacquinoti Ortmann, 1894, previously regarded as a synonym of Scandarma gracilipes (H. Milne Edwards, 1853) (comb. nov.), is here shown to be a junior synonym of Sesarmops angustifrons (A. Milne-Edwards, 1869). Labuanium schuetteii (Hess, 1865) is regarded as conspecific with Scandarma gracilipes (H. Milne Edwards, 1853) (comb. nov.) and the lectotype of the latter species (here designated) is also selected as the neotype of the former, making the two names objective synonyms. Material which had been identified as ‘Labuanium finni Alcock, 1900’ by Pretzmann (1984) from the South Andaman Islands is actually the poorly known Geosesarma thelxinoe (De Man, 1908), which is here referred to a new genus, Andamanium gen. nov. Sesarma finni Alcock, 1900 s.s. is herein assigned to Scandarma. Namlacium crepidatum (Calman, 1925), the only species in the genus, is redescribed and figured and compared with Labuanium and Scandarma. Keys to species of Circulium and Scandarma are provided.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:414B8DAA-584F-4070-A355-83B583D0D017     

Direct ink writing of polycaprolactone/polyethylene oxide based 3D constructs

There has been increasing interest over recent years in the application of three-dimensional(3 D) printing technologies in the biomedical field. One such method is Direct Ink Writing(DIW); this approach has the potential advantage of allowing room-temperature deposition of materials, presented as an ink, to build complex architectures. DIW offers the ability to process biomaterials containing temperature-sensitive components. Due to the fabrication principles of DIW, there are specific rheological requirements that the ink must exhibit for the 3 D construction. For this reason, hydrogel-based liquid feed stocks have been the focal point of ink development. As a consequence, studies based on inks comprising hydrophobic biomaterials, which are insoluble in water and hence unsuited to the hydrogel approach, have been limited.In this study, we investigate novel inks that utilize polycaprolactone(PCL), a hydrophobic polymer, as the primary constituent by dissolving the polymer in solvent systems based on dichloromethane(DCM) and acetone(ACE). Moreover, polyethylene oxide(PEO) was incorporated into the PCL systems in order to extend the range of hydrophilicity of the systems. The rheological properties of the inks were investigated as a function of polymer composition and solvent system. Woodpile constructs of PCL and PCL/PEO were fabricated using DIW method and were assessed by a series of material characterisation. The type of solvent system had a noticeable impact on the ink rheology, which ultimately affected the surface properties. The incorporation of PEO particularly enhanced the roughness and wettability of the constructs. Our results support the use of DIW as a new means to process hydrophobic polymers for biomedical applications.