外源添加物对秸秆还田土壤中无机氮转化影响

采用室内培养方法,研究秸秆不同还田方式土壤中加入无机氮肥和玉米秸秆对无机氮转化的影响。在田间秸秆不同还田处理的土壤中加入氮肥(硫酸铵)培养,初期土壤NH_4~+-N的含量较高,随着培养时间延长,NH_4~+-N的含量下降,培养15天后NH_4~+-N的含量趋于平衡;而土壤中NO_3~--N含量在培养期间逐渐增加,培养30天后NO_3~--N含量趋于平衡;秸秆不同还田处理土壤中添加秸秆培养,粉碎还田处理的土壤中NH_4~+-N的含量在整个培养过程中处于最低,培养后期覆盖还田和高茬还田的土壤NH_4~+-N的含量略有下降。

Macroscopic single-crystal tubes assembled with porous supramolecular architecture of water-soluble calixarene and phenanthroline

Single-crystal tubular products on the millimetre scale have been synthesized from water-soluble calixarene and phenanthroline in the presence of lanthanides by a hydrothermal method, in which the extended structures contain some 1D infinite channels.

Glutathione-capped CdTe quantum dots for the sensitive detection of glucose

A simple and sensitive assay system for glucose based on the glutathione (GSH)-capped CdTe quantum dots (QDs) was developed. GSH-capped CdTe QDs exhibit higher sensitivity to H2O2 produced from the glucose oxidase catalyzed oxidation Of glucose, and are also more biocompatible than other thiols-capped QDs. Based on the quenching of H2O2 on GSH-capped QDs, glucose can be detected. The detection conditions containing reaction time, the concentration of glucose oxidase and the sizes of QDs were optimized and the detection limits for glucose was determined to be 0.1 mu M; two detection ranges of glucose from 1.0 mu M to 0.5 mM and from 1.0 mM to 20 mM, respectively Were obtained. The detection limit was almost a 1000 times lower than other QDs-based optical glucose sensing systems. The developed glucose detection system was simple and facile with no need of complicated enzyme immobilization and modification of QDs.

White electroluminescence from a single polymer system: Improved performance by means of enhanced efficiency and red-shifted luminescence of the blue-light-emitting species

High-efficiency white electrolurninescence from a single polymer is achieved by enhancing the electroluminescence efficiency and effecting a red-shift in the emission spectrum of the blue emissive species. A single-layer device of the resultant polymer exhibits a higher luminous efficiency than the nonmodified species (12.8 cd A(-1), see figure) and an external quantum efficiency of 5.4 % with CIE coordinates of (0.31,0.36), exemplifying the success of the reported methodology.

Morphological, thermal, and mechanical properties of polypropylene/polycarbonate blend

This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer was produced by grafting glycidyl methacrylate (GMA) onto polypropylene in the molten state. Blend morphologies were controlled by adding PP-g-GMA as compatibilizer during melt processing, thus changing dispersion and interfacial adhesion of the polycarbonate phase. With PP-g-GMA, volume fractions increased from 2.5 to 20, and much finer dispersions of discrete polycarbonate phase with average domain sizes decreased from 35 to 3 mu m were obtained. The WAXD spectra showed that the crystal structure of neat PP was different from that in blends. The DSC results suggested that the degree of crystallization of PP in blends decreased as PC content and compatibilizer increased. The mechanical properties significantly changed after addition of PP-g-GMA. (C) 1997 John Wiley & Sons, Inc.

Characterization of 12 single nucleotide polymorphisms (SNPs) in Pacific abalone, Haliotis discus hannai

We report here for the first time 12 polymorphic single nucleotide polymorphisms (SNPs) in a commercially important gastropod, Pacific abalone (Haliotis discus hannai) that were identified by searching expressed sequence tag database. These SNP loci (seven nuclear and five mitochondrial SNPs) were polymorphic among 37 wild abalone individuals, based on a four-primer allele-specific polymerase chain reaction analysis. All loci had two alleles and the minor allele frequency ranged from 0.027 to 0.473. For the seven nuclear SNPs, the expected and observed heterozygosities ranged from 0.053 to 0.499 and from 0.054 to 0.811, respectively.

Sensitisation identification of stainless steel to intergranular stress corrosion cracking by atomic force microscopy

A new technique was developed for characterisation of stainless steel to intergramilar stress corrosion cracking by atomic force microscopy. The technique proved to be effective in sensitisation identification of AISI 304 stainless steel and might be promising in sensitisation identification of other stainless steels. (c) 2007 Elsevier B.V. All rights reserved.

钛铁矿深加工及高钛渣生产中资源综合利用研究

钛矿资源主要包括钛铁矿、金红石、白钛矿和红钛铁矿等,其中钛铁矿约占可利用钛矿资源80%左右,是用途最大的钛矿资源.国外大多利用钛铁矿砂矿,主要生产国家有澳大利亚、南非、加拿大、乌克兰、挪威等国,其产量占世界产量的84%以上.我国钛资源虽然居世界储量之首,但97%为原生钒钛磁铁矿,由于原生矿中TiO2含量均低于10%,且钛铁矿与磁铁矿紧密结合,选治难度较大,因此目前多用于硫酸法钛白的生产原料.