Compensatory growth response in three-spined stickleback in relation to feed-deprivation protocols

Different protocols of food deprivation were used to bring two groups of juvenile three-spined sticklebacks Gaslerosteus aculeatus to the same reduced body mass in comparison with a control group fed daily ad libitum. One group experienced I week or deprivation then 2 weeks on maintenance rations. The second group experienced I week of ad lithium feeding followed by 2 weeks of deprivation. The deprived groups were reduced to a mean mass ore. 80% of controls. The compensatory growth response shown when ad libitum feeding was resumed was independent of the trajectory by which the three-spined sticklebacks had reached the reduced body mass. The compensatory response was Sufficient to return the deprived groups to the mass and length trajectories shown by the control group within 4 weeks. There was full compensation for dry mass and total lipid, but incomplete compensation for lipid-free dry mass. Hyperphagia and increased growth efficiency were present in the re-feeding phase, but there was a lag of a week before the hyperphagia was established. The consistency of the compensatory response of immature three-spined sticklebacks provides a potential model system for the analysis and prediction of appetite and growth in teleosts. (C) 2003 The Fisheries Society of the British isles.

Experimental and theoretical analysis of nondegenerate ultrabroadband chirped pulse optical parametric amplification

Experimental investigations of nondegenerate ultrabroadband chirped pulse optical parametric amplification have been carried out. The general mathematical expressions for evaluating parametric bandwidth, gain and gain bandwidth for arbitrary three-wave mixing parametric amplifiers are presented. In our experiments, a type-I noncollinear phase-matched optical parametric amplifier based on lithium triborate, which was pumped by a 5-ns second harmonic pulses from a Q-switched Nd:YAG operating at 10 Hz, seeded by a 14-fs Ti:sapphire laser at 800 nm, was presented. The 0.85 nJ energy of input chirped signal pulse with 57-FWHM has been amplified to 3.1 muJ at pump intensity 3 GW/cm(2), the corresponding parametric gain reached 3.6 x 10(3), the 53 nm-FWHM gain spectrum bandwidth of output signal has been obtained. The large gain and broad gain bandwidth, which have been confirmed experimentally, provide great potentials to amplify efficiently the broad bandwidth femtosecond light pulses to generate new extremes in power, intensity, and pulse duration using optical parametric chirped pulse amplifiers pumped by powerful nanosecond systems.

Color center conversion by femtosecond pulse laser irradiation in LiF : F-2 crystals

We report the observation of intense spontaneous emission of green light from LiF:F-2:F-3(+) centers in active channel waveguides generated in lithium fluoride crystals by near-infrared femtosecond laser radiation. While irradiating the crystal at room temperature with 405 nm light from a laser diode, yellow and green emission was seen by the naked eye. Stripe waveguides were fabricated by translating the crystal along the irradiated laser pulse, and their guiding properties and fluorescence spectra at 540 nm demonstrated. This single-step process inducing a waveguide structure offers a good prospect for the development of a waveguide laser in bulk LiF crystals.

插层剂在聚合物熔融插层蒙脱土中的作用

近年来，由于有机和无机成分在纳米尺寸上的结合而带来的优异性能使得聚合物／蒙脱土纳米复合材料得到广泛关注。在诸多方法中，因能够使用传统的聚合物熔融挤出、共混等加工设备而无需额外的设备投资，投资低、见效快而且对周围环境没有污染等优点，熔融插层法倍受青睐。然而，通常认为亲油性聚合物无法直接插层蒙脱土，而需要预先用插层剂处理蒙脱土。大多数聚合物是亲油性的，这将大大增加制备材料的成本和工艺的复杂性，并因引入了小分子插层剂而有损材料性能的提高，从而阻碍了该技术的应用和推广。本文从理论上研究了插层剂用量对有机化蒙脱土及聚合物／蒙脱土纳米复合材料微观结构的影响，探索一种无需改性蒙脱土或用很少插层剂改性蒙脱土的制备聚合物／蒙脱土纳米复合材料的方法。1．系统地改变插层剂用量，制备不同的有机化蒙脱土。通过广角X射线衍射、热失重分析、索氏抽提器抽提、差热分析和付立叶红外分析等表征手段，研究了插层剂插层机理以及插层剂在蒙脱土层间的排列方式，为进一步研究有机化蒙脱土在聚合物树脂中的分散奠定基础。结果表明，插层剂插层蒙脱土机理和在蒙脱土层间的排列方式随着插层剂用量的变化而不同。2．用不同的亲油性聚合物熔融插层有机化蒙脱土以制备相应的聚合物／蒙脱土纳米复合材料。用广角嘴射线衍射仪和透射电子显微镜分析研究了蒙脱土在聚合物／蒙脱土纳米复合材料中分散状态。结果表明，随着插层剂用量的减少，蒙脱土片层在聚合物树脂中的分散逐渐由插层型过渡到剥离型，即减少改性蒙脱土时插层剂用量有利于蒙脱土在纳米尺寸上分散于聚合物树脂中。3．用不同的亲油性聚合物直接熔融插层未改性的蒙脱土，广角X射线衍射仪和透射电子显微镜表征结果表明，与蒙脱土片层有相互作用的亲油性聚合物能够直接熔融插层未改性的蒙脱土，获得剥离或插层型聚合物／蒙脱土纳米复合材料，这对于蒙脱土在聚合物改性中的应用具有重要的实际意义和理论意义。4．用共同的母料制备聚丙烯／酸配化聚丙烯／蒙脱土纳米复合材料和尼龙12／酸醉化聚丙烯／蒙脱土纳米复合材料，用广角X射线衍射仪和透射电子显微镜对比分析蒙脱土在聚合物中分散的差异，从而了解聚丙烯与酸配化聚丙烯之间的增容作用对蒙脱土在聚丙烯树脂中分散的影响；同时，用尼龙11和酸配化聚丙烯共插层蒙脱土制备聚丙烯／蒙脱土纳米复合材料，并探讨其增容机理。

聚合物锂离子电池和生物燃料电池的相关研究

本论文分为两个部分研究了铿离子电池和生物燃料电池中的关键材料，主要的创新点和结论如下。采用聚合物电解质是提高铿二次电池性能的有效方法之一。聚合物电解质良好电导率、高铿离子迁移数、宽电化学窗口以及好的机械性能是其应用于铿二次电池中的关键。论文的第一部分主要讨论了聚合物、增塑剂和无机纳米粒子等对复合电解质体系的化学和物理性质的影响。我们采用溶液浇注一浸渍法制备了各种纳米复合聚合物电解质，例如开发出基于PVDFHFP或梳状聚合物基体的全固态以及聚合物和碳酸醋形成的胶体聚合物电解质体系。首次制备了具有较高离子电导率的单离子聚合物电解质。考察了两类纳米粒子填充物对体系的影响：一种是“惰性”发烟硅；另一种是“活性”蒙脱土。比较了全固态和胶体聚合物电解质体系电化学性质的不同之处。采用电化学交流阻抗，示差扫描量热法，X衍射，拉曼光谱，红外光谱，扫描电镜，循环伏安等方法详细研究了聚合物电解质中各组分对体系离子电导率和机械性能的影响。研究结果表明，纳米复合物为开发具有特定电化学和机械性能的电解质提供了一种有效的途径，它对聚合物电解质的物理性质影响明显。纳米粒子的加入增强了体系的机械性能，同时也使体系对溶剂的吸附能力增加。在全固态聚合物电解质中加入增塑剂，形成胶体态聚合物电解质，体系的电导率大大增加。所制备的胶体复合物电解质的室温电导率可以达到10-3s cm-1的数量级，机械强度好，阳离子迁移数高。指出选择合适的添加剂及复合方法，控制界面的结构和形态，形成尽可能多的高导电的界面，是获得电导率高和机械性能良好的聚合物电解质的有效途径。并讨论了聚合物电解质在铿离子电池中的应用。 近年来，针对生物燃料电池的研究得到了广泛关注，其中实现蛋白质酶分子和电极之间的直接电子传递是研究中的热点。论文的第二部分主要研究了生物燃料电池中的酶电极。通过对碳纳米管（MWNTs）进行预处理，使其表面带有功能性官能团，从而可以实现酶分子在碳纳米管表面的固定，同时还保持了其生物活性。采用吸附法将微过氧化物酶-11（MP-11）或葡萄糖氧化酶（GOx）等生物分子固定到MWNTs上制成酶修饰电极，研究MWNTs对酶和电极之间电子传递的促进作用。当酶分子（MP-11，GOX）固定到MWNTs表面后，循环伏安结果显示出一对可逆的氧化还原峰，对应酶分子的直接电子转移。研究结果表明这种方法可以扩展到固定其他生物酶分子以及实现蛋白质酶分子和电极之间的直接电化学，可以获得一系列氧化还原酶分子的电化学参数，如反应速率常数等。同时，我们还研究了酶修饰电极对其底物的电催化反应。研究结果表明，该修饰电极对底物的电化学反应表现出较好的催化活性。我们还研究了酶分子在MWNTs修饰铂微电极上的电化学行为。这些研究为研制生物燃料电池提供了一种固定酶以及制备电极材料较好的方法。

聚甲基丙烯酸多缩乙二醇二酯－锂盐－溶剂三组份凝胶聚合物电解质的制备、导电性能和导电机理研究

由极性聚合物-碱金属盐构成的聚合物固体电解质（SPE）是一类很有前途的离子导电材料。但此类SPE，比通常非水介质电解质溶液约低3个数量级，故极需发展电导率更高的新型SPE材料。目前，由极性（或交联）聚合物、碱金属盐和高介电常数溶剂三组份构成的新一代SPE正在崛起，其室温电导率的达10~（－3）S·cm~(-1)。本工作以甲基丙烯酸多缩乙二醇二酯为大分子单体，研究了三组份凝胶电解质的制备、各组分的变化和温度等对膜强度和电导率的影响；并研究了该凝胶体系中离子传导机理。

High electrical-to-green efficiency high stability intracavity-frequency-doubled Nd:YAG-LBO QCW 532 nm laser with a straight cavity

An electrical-to-green efficiency of more than 10% was demonstrated by intracavity-frequency-doubling a Q-switched diode-side-pumped Nd:YAG laser with a type II lithium triborate (LBO) crystal in a straight plano-concave cavity. An average power of 69.2 W at 532 nm was generated when electrical input power was 666 W. The corresponding electrical-to-green conversion efficiency is 10.4%. To the best of our knowledge, this is the highest electrical-to-green efficiency of second harmonic generation laser systems with side-pumped laser modules, ever reported. At about 66 W of green output power, the power fluctuation over 4 hours was better than +/-0.86%.

X-ray spectroscopy of hollow argon atoms formed on a beryllium surface

The X-rays induced during interaction of highly charged argon ions with a beryllium surface are reported. It is found that the K shell X-ray yield of single particle during interaction of hydrogen-like argon ions was 3.6 x 10(-3), which is five orders more than that of heliumlike argon ions. Moreover, due to the screening the 2s electron, no K X-ray was emitted during interaction of lithium-like argon ions with the beryllium surface. It is also found that the X-ray spectrum induced by Ar17+ interacting with residual gases is very different from that induced by Ar17+ interacting with the surfaces, that provided an experimental evidence for the existence of the hollow atoms below the surface.

Preparation of Microporous Membranes by Swift Heavy Ion Irradiation and Impedance Characterization

Polypropylene (PP) microporous membranes were successfully prepared by swift heavy ion irradiation and track-etching. Polypropylene foils were irradiated with Au-197 ions of kinetic energy 11.4 MeV.u(-1) (total energy of 2245.8 MeV) and fluence 1x10(8) ions.cm(-2) at normal incidence. The damaged regions produced by the gold ions along the trajectories were etched in H2SO4 and K2Cr2O7 solutions leading to the formation of cylindrical pores in the membranes. The pore diameters of the PP microporous membranes increased from 380 to 1610 nm as the etching time increased from 5 to 30 min. The surface and cross-section morphologies of the porous membranes were characterized by scanning electron microscopy (SEM). The micropores in the membranes were found to be cylindrical in shape, homogeneous in distribution, and equal in size. Some mathematical relations of the porosity of the PP microporous membranes were established by analytic derivation. The microporous membranes were used in lithium-ion batteries to measure their properties as separators. The electrical conductivity of the porous membrane immersed in liquid electrolyte was found to be comparable to that of commercial separators by electrochemical impedance spectroscopy (EIS). The results showed that the porosity and electrical conductivity were dependent on the ion fluence and etching time. By adjusting these two factors, microporous membranes with good porosity and electrical conductivity were made that met the requirements for commercial use.

利用重离子辐照及蚀刻技术制备锂离子电池隔膜

本文通过对目前锂离子电池市场及锂离子电池隔膜制备现状的研究，提出采用重离子辐照技术制备锂离子电池隔膜的新方法。拓展了重离子辐照技术的应用，为锂离子电池隔膜的国产化另辟蹊径。实验中，用能量25 MeV/u 的Kr86及11.4 MeV/u的197Au离子，以1×108 cm-2-5×109 cm-2剂量辐照聚丙烯薄膜，通过电导测量法监测蚀刻液的参数，包括温度、硫酸浓度、重铬酸钾浓度对径迹蚀刻速率的影响，得到适合的蚀刻条件；并用场发射扫描电镜对孔的形状及孔径大小进行表征；成功制备出孔径均匀、具有密度和大小可控的重离子径迹聚丙烯孔膜；对孔洞锥角的形成进行分析，给出锥角的计算公式，为利用重离子辐照技术制备锂离子电池隔膜提供了实验数据

Chiral synthesis on catalysts immobilized in microporous and mesoporous materials

This paper reviews the recent progress made in the asymmetric synthesis on chiral catalysts in porous materials and discusses the effects of surface and pores on enantio-selectivity (confinement effect). This paper also summarizes various approaches of immobilization of the chiral catalysts onto surfaces and into pores of solid inorganic supports such as microporous and mesoporous materials. The most important reactions surveyed for the chiral synthesis in porous materials include epoxidation. hydrogenation, hydroformylation, Aldol and Diels-Alder reactions, etc. The confinement effect originated from the surfaces and the pores turns out to be a general phenomenon. which may make the enantioselectivity increase (positive effect) or decrease (negative effect). The confinement effect becomes more pronounced particularly when the bonding between the catalyst and the surface is more rigid and the pore size is tuned to a suitable range. It is proposed that the confinement in chiral synthesis is essentially a consequence of subtle change in transition states induced by weak-interaction in pores or on surfaces. It is also anticipated that the enantioselectivity could be improved by tuning the confinement effect based on the molecular designing of the pore/surface and the immobilized catalysts according to the requirements of chiral reactions.

Dynamic mechanical properties of gel polymer electrolytes containing ionic liquid

The copolymer of acrylonitrile (AN), methyl methacrylate (MMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) is synthesized in 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF(4)). The dynamic mechanical properties of the resulting gel polymer electrolytes containing ionic liquid are measured.

Cationic Lipid Bilayer Coated Gold Nanoparticles-mediated Transfection of Mammalian Cells

Here, we demonstrated dimethyldioctadecylammonium bromide (DODAB), a cationic lipid, bilayer coated Au nanoparticles (AuNPs) could efficiently deliver two types of plasmid DNA into human embryonic kidney cells (HEK 293) in the presence of serum. The transfection efficiency of AuNPs was about five times higher than that of DODAB. The interaction of AuNPs with DNA was characterized with dye intercalation assay and agarose gel electrophoresis. The morphology of the complex of AuNPs with DNA was observed with scanning electron microscope (SEM). The intracellular trafficking of the complex was monitored with transmission electron microscope (TEM).