Study of the synthesis, crystallization, and morphology of poly(ethylene glycol)-poly(is an element of-caprolactone) diblock copolymers

Poly(ethylene glycol) -poly(epsilon-caprolactone) diblock copolymers PEG-PCL were synthesized by ring-opening polymerization of c-caprolactone using monomethoxy poly(ethylene glycol) as the macroinitiator and calcium ammoniate as the catalyst. Obvious mutual influence between PEG and PCL crystallization was studied by altering the relative block length. Fixing the length of the PEG block (M-n = 5000) and increasing the length of the PCL block, the crystallization temperature of the PCL block rose gradually from I to about 35 degreesC while that of the PEG block dropped from 36 to -6.6 degreesC. Meanwhile, the melting temperature of the PCL block went up from 30 to 60 degreesC, while that of the PEG block declined from 60 to 41 degreesC. If the PCL block was longer than the PEG block, the former would crystallize first when cooling from a molten state and led to obviously imperfect crystallization of PEG and vice versa. And they both crystallized at the same temperature, if their weight fractions were equal. We found that the PEG block could still crystallize at -6.6 degreesC even when its weight fraction is only 14%. A unique morphology of concentric spherulites was observed for PEG5000-PCL5000.

Highly efficient pure-white-light-emitting diodes from a single polymer: Polyfluorene with naphthalimide moieties

Light-emitting diodes exhibiting efficient pure-white-light electroluminescence have been successfully developed by using a single polymer: polyfluorene derivatives with 1,8-naphthalimide chromophores chemically doped onto the polyfluorene backbones. By adjusting the emission wavelength of the 1,8-naphthalimide components and optimizing the relative content of 1,8-naphthalimide derivatives in the resulting polymers, white-light electroluminescence from a single polymer, as opposed to a polymer blend, has been obtained in a device with a configuration of indium tin oxide/poly(3,4-ethyleiledioxythiophene)(50 nm)/polymer(80 nm)/Ca(10 nm)/Al(100 nm). The device exhibits Commission Internationale de I'Eclairage coordinates of (0.32,0.36), a maximum brightness of 11900 cd m(-2), a current efficiency of 3.8 cd A(-1), a power efficiency of 2.0 lm W-1. an external quantum efficiency of 1.50 %, and quite stable color coordinates at different driving voltages, even at high luminances of over 5000 cd m(-2).

Composition dependence of the crystallization behavior and morphology of the poly(ethylene oxide)-poly(epsilon-caprolactone) diblock copolymer

The crystallization behavior and morphology of the crystalline-crystalline poly(ethylene oxide)-poly(epsilon-caprolactone) diblock copolymer (PEO-b-PCL) was studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), small-angle X-ray scattering (SAXS), and hot-stage polarized optical microscope (POM). The mutual effects between the PEO and PCL blocks were significant, leading to the obvious composition dependence of the crystallization behavior and morphology of PEO-b-PCL. In this study, the PEO block length was fixed (M-n = 5000) and the weight ratio of PCL/PEO was tailored by changing the PCL block length. Both blocks could crystallize in PEO-b-PCL with the PCL weight fraction (WFPCL) of 0.23-0.87. For the sample with the WFPCL of 0.36 or less, the PEO block crystallized first, resulting in the obvious confinement of the PCL block and vice versa for the sample with WFPCL of 0.43 or more. With increasing WFPCL, the crystallinity of PEO reduced continuously while the variation of the PCL crystallinity exhibited a maximum. The long period of PEO-b-PCL increased with increasing WFPCL from 0.16 to 0.50 but then decreased with the further increase of WFPCL due to the interaction of the respective variation of the thicknesses of the PEO and PCL crystalline lamellae.

Influence of crystal structure on the luminescence properties of bismuth(III), europium(III) and dysprosium(III) in Y2SiO5

The luminescence properties of Bi3+, EU(3+), Dy3+ and energy transfer from Bi3+ to Dy3+ and EU(3+) have been studied in two modifications of Y2SiO5 (low-temperature X(1) type and high-temperature X(2) type) and discussed in relation to their crystal structures. The Bi3+ ion luminesces in the blue region of the spectrum in X(1)-Y2SiO5 but in the UV region in X(2)-Y2SiO5. Two obviously different luminescent centres have been observed for Bi3+ and Eu3+ ill X(1)-Y2SiO5, but only one has been seen in X(2)-Y2SiO5. The Stokes shift (9200 cm(-1)) for Bi3+ in X(1)-Y2SiO5 is much larger than that (5000 cm(-1)) in X(2)-Y2SiO5. This suggests that the host lattice is more rigid in X(2)-Y2SiO5 than in X(1)-Y2SiO5. As a result, the Bi3+, EU(3+) and Dy3+ ions show higher emission intensity in the former than in the latter type. X(1)-Y2SiO5 is more suitable for Bi3+ --> EU(3+) energy transfer and X(2)-Y2SiO5 is more suitable for Bi3+ --> Dy3+ energy transfer.

SIMULTANEOUS DETERMINATION OF GUANINE, URIC-ACID, HYPOXANTHINE AND XANTHINE IN HUMAN PLASMA BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH AMPEROMETRIC DETECTION

A reversed-phase high-performance liquid chromatographic method with amperometric detection is described for the separation and quantification of uric acid, guanine, hypoxanthine and xanthine. The isocratic separation of a standard mixture of the compounds was achieved in 5 min on a Spherisorb 5 C-18 reversed-phase column, with a mobile phase of NaH2PO4 (300 mmol dm(-3) pH 3.0)-methanol-acetonitrile-tetrahydrofuran (97.8 + 0.5 + 1.5 + 0.2). Uric acid, guanine, hypoxanthine and xanthine were completely separated, with detection limits in the range 2-20 pmol per injection. The effect of pH and the composition of the mobile phase on the separation are described. The hydrodynamic voltammograms of these compounds were recorded at a glassy carbon electrode. The linear range of the calibration graph for each compound was: uric acid; 1-5000 mu mol dm(-3); guanine, 0.5-2000 mu mol dm(-3); hypoxanthine, 0.1-500 mu mol dm(-3) and xanthine, 0.5-5000 mu mol dm(-3). The within- and between-day precision was good. The uric acid and hypoxanthine content in human plasma was measured using the proposed method. Good recoveries of uric acid (97.9-103%), hypoxanthine (98.0-99.2%), guanine (96.0-98.3%) and xanthine (96.0-102%) were obtained from human plasma. The results of electrochemical detection were in good agreement with those of UV detection.

共价氢化物发生-光度分析法高选择性的研究与应用——Ⅰ.锗、砷、硒共价氢化物性质初探及其分别测定时其它氢化物干扰的消除

本文采用氢化物发生-银溶胶光度分析法探讨了GeH_4、AsH_3和H_2Se的性质,并利用共价氢化物气体分离柱分别建立了测定锗、砷时消除其它可生成氢化物元素干扰的简便、高效方法。测定1.0μg Ge(Ⅳ),5000μg As(Ⅴ)、Bi(Ⅱ)、Pb(Ⅰ)、1000μg Sb(Ⅱ)、Sn(Ⅰ)、500μg As(Ⅱ)和100μg Se(Ⅳ)、Sn(Ⅳ),Te(Ⅳ)不产生干扰。对砷的测定,其它共价氢化物元素的允许倍数分别为:Sb(Ⅱ)(5000)、Pb(Ⅰ)(5000)、Bi(Ⅱ)(5000)、Sn(Ⅰ)(1000)、Se(Ⅳ)(100)、Te(Ⅳ)(100)和Ge(Ⅳ)(15)。

薄膜CdS/Cu_2S太阳电池寿命与温度关系的探讨

对薄膜CdS/Cu_2S光伏器件稳定性的研究表明,温度对电池寿命的影响是不可忽视的因素。J·Meikin指出,在40℃下对CdS/Cu_2S电池加热5000小时,Ⅰ_(sc)仅下降1％;对于包封电池,K.Boer得出,在60℃下加热两年电池性能没有发生衰变的结论。 我们通过对CdS/Cu_2S太阳电池的加热寿命试验,寻求器件寿命与温度间的关系,并用

中国红参中碳、氢、氮元素和蛋白含量的自动分析

人参为五加科植物人参(Panax ginseng C.A.Mey.)的干燥根。红参则是鲜人参洗净后经高温蒸气加热后干燥而制得的产品。有关人参中皂甙、氨基酸、多肽、挥发油、微量元素等成分的研究国内外均有大量的报道。但关于红参中碳、氢、氮元素的研究以及自动定量方法国内外尚未见报道。 1.仪器:1106型元素自动分析仪(意大利)其配套设备包括B-5000型记录仪,微处理机和电子天平。 2.人参样品:1号红参由吉林省抚松县参茸公司提供。2号红参由抚松县漫江参场提供。3号红参为抚松县参场提供。4号红参由延边地区提供。5号红参由集安县新开河参场提供。上述样品均为6年生。

Geological records of marine environmental changes in the southern Okinawa Trough

Indexes of sediment grain size, sedimentation rates, geochemical composition, heavy minerals, benthic foraminiferal fauna, indicator species of the Kuroshio Current, paleo-SST and carbonate dissolution of core E017 conformably suggest a great marine environmental change occurring at about 10.1-9.2 cal. kaBP in the southern Okinawa Trough, which may correspond to the strengthening of the Kuroshio Warm Current and re-entering the Okinawa Trough through the sea area off northeast Taiwan. The invasion of Kuroshio current has experienced a process of gradual strengthening and then weakening, and its intensity became more fluctuation during the last 5000 years. Compared to the transition of sediment grain size, geochemical composition and heavy minerals, the foraminiferal faunas show a 900-year lag, which may indicate that the invasion of Kuroshio Current and the consequent sea surface and deep-water environmental changes is a gradual process, and fauna has an obvious lag compared to environment altering. The carbonate dissolution of the Okinawa Trough has had an apparent strengthening since 9.2 cal. kaBP, and reached a maximum in the late 3000 years, which may be caused by the deep-water environmental changes due to the invasion of Kuroshio Current.

末次冰消期以来东亚季风演化：来自东海和北黄海沉积孢粉记录

本论文通过对冲绳海槽南部的MD05-2908孔、北黄海的B-U35、B-U41、B-L44孔和北黄海的299份表层样中的孢粉组成、堆积速率、有机碳氮同位素的综合研究，分析了北黄海的孢粉来源、传播动力和途径，并与其它古气候记录对比，重建了末次冰消期以来东亚季风的演化。 MD05-2908孔孢粉组合特征显示6800-3800a BP间气候温暖干燥，其间存在着两次明显的温度降低、湿度增加阶段，即6800-6600a BP和5800-4850a BP；3800a BP以后，气候变得比较寒冷湿润，中世纪暖期和小冰期分别位于990-480a BP和480-230a BP。 北黄海表层孢粉百分含量等值线图显示北黄海不同海域孢粉来源不同，北黄 海东部海域(123.5°E以东的陆架区域)孢粉主要来源于鸭绿江；北黄海中部海域(123.5°E-122.6°E的陆架区域)孢粉来源比较复杂，既有来自辽东半岛、沿海岛屿、山东半岛，还有由黄海暖流携带而来的；北黄海西部海域(122.6°E以西的陆架区域)孢粉以黄海沿岸流携带而来的黄河来源的为主。 北黄海表层孢粉百分含量等值线图还显示，北黄海东部海域孢粉分布主要受 鸭绿江冲淡水影响，波浪和潮汐的作用较弱；北黄海中部海域孢粉分布受黄海暖流和辽东沿岸流的分支共同影响；黄海暖流与黄海沿岸流在山东半岛东北部相遇，形成一逆时针方向的涡旋，该涡旋控制着北黄海西部海域孢粉的分布。 B-U35孔、B-U41和B-L44孔孢粉组合特征显示，12830-12350a BP时气候 寒冷干燥，植被以旱生草本植物为主，时间上可能对应YD事件；12350-10100a BP时植被以针叶林为主，林下生长着大量蕨类植物，气候寒冷湿润，可能对应着YD事件；10100-6600a BP时植被以落叶阔叶林为主，伴生大量旱生草本植物，气候温暖干燥；6600-5000a BP时植被以针叶-落叶阔叶混交林为主，旱生草本植物含量下降，相对上一阶段温度有所降低，但气候更湿润，可能对应全新世最佳期；5000-4000a BP时针叶林所占比例扩大，温度再次降低，湿度变化不明显；4000-500a BP旱生草本植物含量增加，气候寒冷干燥；500a BP-至今，受人类活动影响，植被遭到严重破坏。 B-U35孔和B-U41孔淡水水生植物花粉百分含量曲线显示11750a BP以来黄河河口地区沼泽湿地面积几经变化。10100-6600a BP时沼泽湿地范围在上一阶段的基础上进一步扩大；6600-2850a BP间沼泽湿地大面积缩小，水生植物属种式微；2850a BP之后黄河河口地区沼泽湿地面积再次扩大，水生植物重新繁盛。 MD05-2908孔蕨类孢子百分含量被用来作为中国东南部季风演化的代用指标。结果显示6800-3800a BP时夏季风较强，其间有两次夏季风减弱阶段，分别位于6800-6600a BP和5800-4850a BP，3800a BP以来，夏季风明显减弱，此期的夏季风减弱除受太阳辐射量的减少影响外，可能还与El Nino的频繁爆发有关。 B-U35孔和B-U41孔蒿属、藜科、麻黄科百分含量被用来作为中国中北部夏季风演化的代用指标。研究表明，11750a BP以来东亚夏季风强度在10100-6600a BP时，显著加强，6600a BP左右，夏季风开始减弱，4000a BP以后夏季风显著减弱。 将MD05-2908孔、B-U35孔和B-U41孔夏季风代用指标进行对比发现，中晚全新世以来中国南-北湿度变化特征正好相反，东亚夏季风强度变化以及由此引起的雨锋的南进北撤可能是导致中国不同区域中晚全新世以来降雨量不同的主要原因。

冲绳海槽地壳上地幔电性结构

大地电磁（MT）方法是一种新发展的地球物理技术，近十年已被国外越来越多的研究者用于海底电磁场的调查，旨在获得海底的电性结构。基于自1990年3月10至1990年3月22日在中日全用KX90-1航次以一海底电位磁力计（OBEM）于31°52.47'N, 129°7.17'E，水深884米处所取得的电磁场资料，通过各种数字信号处理，得到一维大地电磁的测深结果，首次确定了冲绳海槽北部的电性结构如下：层位（向下） 电阻率（欧姆·米） 厚度（千米） 1 0.3 3 2 5000 20 3 0.6 4 4 5000 13 5 100 100 基底 2 ∞，根据已知的冲绳海槽及周转地区的地质地球物理资料，对于所研究地区从以上的电性结构可以得到以下几点主要认识：1、莫霍面埋深或地壳厚度约为27千料；2、岩石圈厚度约40千米；3、软流圈厚度约100千米；4、壳内高导层是由于岩石的熔融或部分熔融；5、热流值大致在60-100毫瓦/米~2。

Identification of factors affecting the growth and survival of the settling Japanese flounder larvae, Paralichthys olivaceus

A series of experiments were conducted to identify the factors that affected the growth and survival of the settling flounder larvae Paralichthys olivaceus. Settling larvae 24 days after hatching (DAH) were reared in 10-l experimental tanks up to 40 DAH, and two of the following factors were changed as controlled factors in each experiment: light regime (24L:0D or 12L:12D), prey density (1500, 3000, or 5000 Artemia l(-1)), shelter (sand or no sand) and stocking density (5, 10, or 15 fish l(-1)). Early settling larvae (24-35 DAH) experienced little mortality (less than 10% of the overall mortality) that was not significantly affected by above factors. In contrast, late settling larvae (36-40 DAH) suffered high cannibalistic mortality which was significantly influenced by each of the above factors. Larvae experienced significantly lower mortality at 10 fish l(-1) level than at other densities. Larvae at 15 fish l(-1) level had higher mortality than at 5 fish l(-1) when all other factors were identical. Larvae at 3000 and 5000 Artemia l(-1) treatments survived significantly better than at 1500 Artemia l(-1), but no significant differences in larval mortality were found between the two higher densities. Larvae suffered higher mortality at low prey density or at the absence of sand when they were exposed to longer photoperiod. Low stocking density significantly improved the growth of the settling larvae. The average daily instantaneous growth rate (G) at 5 and 15 fish l(-1) treatments were 0.050 and 0.034, with the coefficient of variation (CV) in final length at 16.4 and 23.5, respectively. Daily instantaneous growth rate increased significantly from 0.033 in the 1500 Artemia l(-1) to 0.041 and 0.045 in the 3000 and 5000 Artennia l(-1), respectively, but no significant difference in larval growth existed between the two higher prey densities. These findings suggested that the optimal prey density for growth and survival of the settling flounder larvae at a stocking density of 5 - 15 fish l(-1) was around 3000 Artemia l(-1) . Larvae that were exposed to 24L showed 20% increase in growth ( G = 0.046, CV = 18.7) than those exposed to 12L ( G = 0.037, CV = 20.5). Longer exposure to light significantly improved larval growth, provided sufficient food was available. Sand substrate did not show significant effects on larval growth, possibly because the larvae spent most of the time swimming or feeding in the water column during this stage. (C) 2003 Elsevier Science B.V. All rights reserved.

Triterpane and sterane biomarkers in the YA13-1 condensates from Qiongdongnan Basin, South China Sea

Triterpanes and steranes in condensates from the YA13-1 gas field, Qiongdongnan Basin, were monitored. The YA13-1 condensates have unusual biomarker distributions dominated by terpanes and steranes derived from higher plants. Anomalously abundant 1 got-oleanane and remarkably abundant bicadinanes are present in the YA13-1 condensates, whereas the 17alpha-hopane contents are extremely low. Taraxastane and significantly abundant 17alpha-diahopanes occur in the condensates. In addition, a number of unknown C-29 and C-30 pentacyclic triterpanes including previously unreported compounds were detected in the condensates, some of which are significantly abundant. The unknown compounds may be terrestrial biomarkers. C-29 homologues are relatively predominant among the regular and rearranged steranes. The diasterane concentrations are markedly higher than those of regular steranes. The maturity of the YA13-1 condensates is relatively high, at the peak to late oil generation stage (corresponding to 0.85-1.10% Ro), based on sterane and terpane and including bicadinane maturity parameters (i.e. T/(T-1 + R) and 2T/R bicadinane ratios). The above maturity assessment result is different from that based on diamondoid maturity parameters (%Ro = 1.60-1.70) [Org. Geochem. 25 (1996) 179], which can be explained by a contribution of hydrocarbons from two sources at different depths. The YA13-1 condensates were probably generated from the Yacheng and Lingshui coal-bearing source rocks buried both in the Qiongdongnan Basin (3400-5000 m) and in the Yinggehai Basin (>5000 m). The possible contribution of lower maturity hydrocarbons from the Yacheng and Lingshui Formations (3400-4100 m) in the Qiongdongnan Basin to the YA13-1 gases and condensates should not be neglected. (C) 2003 Elsevier Science B.V. All rights reserved.

Inhibition of egg hatching success and larvae survival of the scallop, Chlamys farreri, associated with exposure to cells and cell fragments of the dinoflagellate Alexandrium tamarense

We report an apparently novel toxic effect of the dinoflagellate Alexandrium tamarense, manifested by inhibition of the egg hatching success of the scallop, Chlamys farreri. The hatching rate of C. farreri approached only 30% of controls when its fertilised eggs were exposed for 36 h to A. tamarense cells or cellular fragments at a concentration of 100 cells/ml, and the hatching rate was just 5% after exposure to A. tamarense of 500 cells/ml. Similar exposures of the fertilised scallop eggs to two other algal species, the diatom Phaeodactylum tricornutum and the raphidophyte Heterosigma carterae, resulted in no such toxicity or inhibitory effects.. Likewise, exposure of eggs to standard STX toxin. as well as to A. tamarense cell contents (supernant of re-suspended algal cells following ultrasonication and centrifugation), did not elicit this inhibitory response. However, exposure of the scallop eggs to cell cultures, intact algal cells, or cell fragments of A. tamarense produced marked toxicity. The alga also influenced larvae at early D-shape stage of scallop. The survival rates began to decrease significantly after exposed for 6 days at concentration of 3000 cells/ml and above: no larvae could survive after 14-day exposure to A. tamarense at 10,000 cells/ml or 20-day at 5000 cells/ml. The results indicated the production of novel substances from A. tamarense which can cause adverse effects on egg hatching and survival of the scallop larvae, The experiment also found that the developmental stages before blastula was the developmental period most sensitive to the A. tamarense toxin(s) and the alga at early exponential stage had the strongest effect on egg hatching comparing with other growth phases. The adverse effect of A. tamarense on early development of scallops may cause decline of shellfish population and may have further impact on marine ecosystem. (C) 2001 Elsevier Science Ltd. All rights reserved.

Effects of diet, stocking density, and environmental factors on growth, survival, and metamorphosis of Manila clam Ruditapes philippinarum larvae

A series of experiments was conducted to evaluate the effects of diet, stocking density, and environmental factors on growth, survival, and metamorphosis of Manila clam Ruditapes philippinarum larvae. These experiments examined the following factors: diet (Isochrysts spp., Chlorella spp., and a mixture of Isochrysis spp. and Chlorella spp. [ 1: 1 w/w]), stocking density (5, 10, 15, and 20 larvae ml(-1)), light intensity (un-shaded, partially shaded, and fully shaded), water filtration (unfiltered and sand-filtered), water exchange (50% and 100% once every other day, 25%, 50%, and 100% once daily; 50% and 100% twice daily), and the use of substrate (with and without sand as the substrate). Results indicated that Chlorella spp. could replace 50% of Isochrysis spp. as a food source for the Manila clam larvae without affecting growth, survival, and metamorphosis. Larval growth decreased significantly with increasing stocking density. A density of 5-10 larvae ml(-1) appeared to be optimal for normal growth of Manila clam larvae. Neither diet nor stocking density used in the study had a significant effect on larval survival. Under partially shaded (light intensity = 1000-5000 lx) and fully shaded (light intensity <500 lx) conditions, larval growth was significantly faster than under direct sunlight (un-shaded). A water exchange rate of 50% twice daily provided optimum larval growth. Larvae grew significantly faster in the unfiltered water than in the sand-filtered water. Using sand as the substrate in the culture system significantly depressed the metamorphosis rate. The type and particle size of sand used as the substrate did not significantly affect growth and metamorphosis rates of the larvae. (C) 2005 Published by Elsevier B.V.