Investigation of DyBa2Cu3O7-d superconducting domains grown by the infiltration technique starting with small size Dy-211 particles

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy-211 particles. The starting materials are the 211-particles and a barium and copper rich liquid phase precursor. The infiltration and growth process allows for controlling both the spatial and size distribution of the 211-particles in the final superconducting 123-single-domain. The main parameters (set-ups, maximum processing temperature with respect to the peritectic temperature, nature of reactant, porosity of the 211-preform) of the infiltration and growth process are discussed. Moreover, different processes of chimie douce are shown in order to produce Dy-211 particles with controlled shape and size, particles that can be used as precursors for the infiltration and growth process. © 2005 IOP Publishing Ltd.

Parentage determination of an isolated Yangtze finless porpoise population Neophocaena phocaenoides asiaeorientalis in the Yangtze Tian-e-Zhou Baiji National Natural Reserve based on molecular data

Reproductive behaviors are poorly known for the Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis. In this study, the parentage of an isolated Yangtze finless porpoise population inhabiting the Yangtze Tian-e-Zhou Baiji National Natural Reserve is determined by analysis of microsatellite loci and mitochondrial DNA (mtDNA) control region sequences, and the porpoise's reproductive behaviors are studied. Overall 4 full parentage assignments and additional 3 single parentage assignments were determined for the population of 23 individuals. The analysis shows that their estimated reproductive cycle is shorter than that reported previously and there probably exists an overlapping between gestation and lactation period. The Study also shows that the female does not show fidelity to a particular male for breeding and vice versa, the oldest males did not monopolize mating and the dominance rank could not be so strict for the porpoise society. Moreover, the porpoise's mating pattern and relatedness among candidate parents are discussed here. These results provide important information for making guidelines of management and conservation for this protected population.

Mobilization potential of heavy metals: A comparison between river and lake sediments

Toxic metals introduced into aquatic environments by human activities accumulation in sediments. A common notion is that the association of metals with acid volatile sulfides (AVS) affords a mechanism for partitioning metals from water to solid phase, thereby reducing biological availability. However, variation in environmental conditions can mobilize the sediment-bound metal and result in adverse environmental impacts. The AVS levels and the effect of AVS on the fate of Cu, Cd, Zn, Ni in sediments in the the Changjiang River, a suboxic river with sandy bottom sediment and the Donghu Lake, a anoxic lake with muddy sediment in China, were compared through aeration, static adsorption and release experiments in laboratory. Sips isotherm equation, kinetic equation and grade ion exchange theory were used to describe the heavy metal adsorb and release process. The results showed that AVS level in the lake sediment are higher than that of the river. Heavy metals in the overlying water can transfer to sediments incessantly as long as the sediment remains undisturbed. The metal release process is mainly related to AVS oxidation in lake sediment while also related to Org-C and Fe-Mn oxyhydroxide oxidation in river sediment. The effect of sulfides on Zn and Ni is high, followed by Cd, and Cu is easy bound to Org-C. AVS plays a major role in controlling metals activity in lake sediment and its presence increase the adsorption capacity both of the lake and river sediments.

Molecular and morphological data suggest that Spinibarbus caldwelli (Nichols) (Teleostei : Cyprinidae) is a valid species

The taxonomic problem of the cyprinid species of genus Spinibarbus, occurring in southern China and northern Vietnam, was resolved on the basis of molecular and morphological analyses. Spinibarbus caldwelli and Spinibarbus hollandi have a smooth posterior edge of the last unbranched dorsal fin ray among species in the genus. Spinibarbus caldwelli is currently regarded as a junior synonym of S. hollandi because of ambiguities in diagnostic characters. In this article, 11 mtDNA cytochrome b sequences of Spinibarbus specimens were analyzed together with Barbodes gonionotus and Puntius conchonius as outgroups. Our results showed that specimens identified as S. hollandi from Taiwan were different from those from the Asian mainland at a high level of genetic divergence (0.097-0.112), which is higher than that between the two valid species, S. sinensis and S. yunnanensis ( 0.089), and suggested that Taiwan specimens should be considered as a different species from the Asian mainland one. In a molecular phylogenetic analysis, the sister-group relationship between Taiwan specimens and the Asian mainland specimens was supported strongly by a high confidence level ( 100% in bootstrap value). Further analysis of morphological characters showed that overlap of diagnostic characters is much weaker than previously suggested. Taiwan specimens had 8 branched rays in the dorsal fin, whereas those from the mainland had almost 9-10. The molecular and morphological differences suggest S. caldwelli to be valid. The molecular divergence shows the genetic speciation of S. hollandi and S. caldwelli might have occurred 5.6-4.9 million years ago; the former could be a relict species in Taiwan, and the latter dispersed in the Asian mainland.

Linichthys: A new genus of Chinese cyprinid fishes (Teleostei : Cypriniformes)

yLinichthys, new genus, is proposed for Barbodes laticeps Lin and Zhang, 1986. It can be separated from all other genera of Asian Barbinae in having a shallow depression extending along the median portion of the upper lip. Linichthys is superficially very similar to the type species of a monotypic Chinese cyprinid cavefish genus, Typhlobarbus nudiventris, in having an elongate and somewhat compressed body form, a truncate distal margin of the dorsal fin, and a soft and smooth last unbranched dorsal-fin ray, all of them being atypical for most of Asian barbins. The two genera differ in size of the eye and the number of rows of pharyngeal tooth. Although the same body form and/or structure of the dorsal fin are also shared with some species currently placed in other genera of Asian barbins, the recognition of Linichthys is warranted because of their marked differences in other characters. A redescription is also provided for the type species of the monotypic genus, Linichthys laticeps. It is known only from the upper and middle Zhu Jiang basin and the upper Chang Jiang basin in the city of Guiyang, Guizhou Province, South China.

Complex mutation at a microsatellite locus in sturgeons: Acipenser sinensis, A-schrenckii, A-gueldenstaedtii and A-baerii

Cross-species amplifications of microsatellite locus Spl-106, which was originally screened from the genome of shovelnose sturgeon (Scaphirhynchus platorynchus) with a perfect TAGA repeat motif, were carried out in four other species of the genera Acipenser. A total of 34 polymerase chain reaction (PCR) products representing 16 different alleles of this locus was sequenced. Sequence analysis results showed that besides the number changes of repeat units, many mutational events, such as single-base substitutions and various insertion/deletion (indels) occurred not only at species level but also at individual level, even among the different alleles within the same individual. The repeat motifs varied from perfect (TAGA)n array to perfect compound (TAAA)m (GAAA)n and perfect or imperfect compound (TAAA)m (TAGA)n (TAAA)x arrays in different species and different individuals. The evolution dynamics of this locus in sturgeons was inferred in that it may evolve from a single perfect to different perfect or imperfect compounds.

Microsatellites assessment of Chinese sturgeon (Acipenser sinensis Gray) genetic variability

Four microsatellites were used to examine the genetic variability of the spawning stocks of Chinese sturgeon, Acipenser sinensis, from the Yangtze River sampled over a 3-year period (1999-2001). Within 60 individuals, a total of 28 alleles were detected over four polymorphic microsatellite loci. The number of alleles per locus ranged from 4 to 15, with an average allele number of 7. The number of genotypes per locus ranged from 6 to 41. The genetic diversity of four microsatellite loci varied from 0.34 to 0.67, with an average value of 0.54. For the four microsatellite loci, the deviation from the Hardy-Weinberg equilibrium was mainly due to null alleles. The mean number of alleles per locus and the mean heterozygosity were lower than the average values known for anadromous fishes. Fish were clustered according to their microsatellite characteristics using an unsupervised 'Artificial Neural Networks' method entitled 'Self-organizing Map'. The results revealed no significant genetic differentiation considering genetic distance among samples collected during different years. Lack of heterogeneity among different annual groups of spawning stocks was explained by the complex age structure (from 8 to 27 years for males and 12 to 35 years for females) of Chinese sturgeon, leading to formulate an hypothesis about the maintenance of genetic diversity and stability in long-lived animals.

Growth and antioxidant system of the cyanobacterium Synechococcus elongatus in response to microcystin-RR

Microcystins, one type of the cyanobacterial toxins, show a broad range of hazardous effects on other organisms. Most of the researches on the toxic effects of microcystins have involved in animals and higher plants. Little work, however, has been done on evaluating the mechanisms of microcystin toxicity on algae. In this study, the toxicological effects of microcystin-RR (MC-RR) on the cyanobacterium Synechococcus elongatus were investigated. For this purpose, six physio-biochemical parameters (cell optical density, reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST)) were tested in algal cells when exposed to 100 mug(-1) microcystin-RR. The results showed that the growth of Synechococcus elongatus ( expressed as optical density) was significantly inhibited compared with the control. At the same time, the treated algae exhibited a pronounced increase in production of ROS and MDA after 6 days exposure to microcystin-RR. Signi. cant changes in GSH levels and GSH-Px, GSH activities were also detected in algal cells, with higher values being observed in the toxin treated algae after 6 days exposure. GST activities in the treated algae exhibited a decline after exposure and rapid augmentation on day 3, thereafter, they kept at a high level when compared to the control group. GSH contents and GSH-Px activities were also significantly raised in the toxin-treated algae cells from day 3, but they showed a sharp decrease on day 4, which was the onward of cell proliferation. These results suggested that oxidative stress manifested by elevated ROS levels and MDA contents might be responsible for the toxicity of microcystin to Synechococcus elongatus and the algal cells could improve their antioxidant ability through the enhancement of enzymatic and non-enzymatic preventive substances.

Impacts of Choerospondias axillaris growth on acidity of Udic Ferrosols in subtropical China

Changes in acidity of Udic Ferrosols, caused by growth of Choerospondias axillaris (Roxb.) Burtt et Hill, in comparison to wild grass, were investigated for pH distribution in the soil profile, exchangeable acidity, and cation status in the soil leachate of a simulated leaching experiment. Soils were sampled in profiles at 5 cm intervals to a depth of 100 cm. In the 1.5-60 cm layer the soils with 10-year old C. axillaris had significantly lower pH (P < 0.05), with the largest difference being 0.41: and in the 25-75 cm soil depths, especially in the 30-55 cm layer, the soils had a significantly higher exchangeable acidity, ranging 1.93 to 3.02 cmol(c) kg(-1). There was also higher aluminum, potassium, and sodium contents in the soil leachate under C. axillaris than with wild grasses. This suggested that the growth of C. axillaris accelerated acidification of Udic Ferrosols and promoted soil clay mineral weathering.

Toxicity of cypermethrin on growth, pigments, and superoxide dismutase of Scenedesmus obliquus

Cypermethrin is a synthetic pyrethroid that is particularly toxic to crustaceans. It is therefore applied as a chemotherapeutant in farms for the treatment of pests. The effective concentrations of cypermethrin on the inhibition of Scenedesmus ohliquus growth at 96h (96h EC50) were determined to be 50, 100, 150, 200, and 250mg/L. Algal growth, pigment fractions, and the activity of superoxide dismutase (SOD) in the algal cells were measured in the exponential phase after exposure to cypermethrin. The results show that higher concentration of cypermethrin is inhibitory for growth and other metabolic activities and the 96h EC50 of cypermethrin to S. ohliquus is 112 +/- 9 mg/L; the potential application of SOD activity in S. ohliquus as a sensitive biomarker for cypermethrin exposure is also discussed. (C) 2004 Elsevier Inc. All rights reserved.

多能态离子注入法制备磁性半导体的方法

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地热利用技术

本书是《21世纪可持续能源丛书》之一。地热是新能源家族中重要能种之一。本书从地热地表显示温泉、火山、喷泉等现象的描述，进一步引申到与地热相关的基本概念、理论和知识并结合全球地热资源分布规律以及地热勘探、开发利用和保护的现状加以介绍。全书着重以我国地热资源当前开发现状和近期发展趋势分析做了详细阐述，内容丰富，图文并茂，理论联系实际，通俗易懂。可供从事和关心新能源和可再生能源的技术人员、管理人员和各类读者以及有关大专院校师生阅读或作参考用书。

Phase locking of fibre lasers by self-imaging resonator

Experimental demonstrations of the use of a self-imaging resonator in the phase locking of two fibre lasers are presented. The output power of the phase-locked fibre laser array exceeded 2 W Successful attempts of phase locking show that the fibre laser array is not only capable of producing high Output Power but also large on-axis intensity by this method.

Pulse-front matched ultra-broadband optical parametric chirped pulse amplifier for sub-12 fs pulse generation

We propose a LBO-based ultra-broadband chirped pulse optical parametric amplifier employing pulse-front-matching to yield transform-limited sub-12-fs pulses. Measurement of the maximum possible gain bandwidth for the LBO-based OPCPA demonstrates more than 60nm gain bandwidth FWHM. For the generation of TL pulses by the use of this OPCPA, a suitable combination of OPCPA and PFM is first presented. The PFM pump geometry realizes tilt-free signal amplification, and permits this OPCPA to generate TL sub-12-fs pulses.