~(17)B的晕结构特征

实验利用束流衰减法测量了43.7AMeV丰中子核17B与C靶反应的总截面σR=(1724±93)mb.用零程Glauber计算,假定17B具有核芯15B和两个价中子结构,输入GG和GO密度分布,计算的激发函数曲线与该实验数据很好符合,输入描述稳定核双参数Fermi密度分布,不能得到与实验数据符合的结果,表明17B是核芯15B+2n的假定是合理的.并且中子密度分布表现较大空间扩展-晕结构特征.

1,2,4-三氯苯胁迫对大豆下胚轴膜脂过氧化的影响

以盆栽法研究了不同浓度1,2,4-三氯苯(TCB)胁迫对大豆下胚轴膜脂过氧化作用的影响。结果表明,100—300μg·g-1TCB胁迫初期(1—3d)促使萌发大豆下胚轴内过氧化氢(H2O2)的积累显著增加,同时伴随质膜电解质渗漏率和组织自动氧化速率升高,显示发生膜脂质过氧化作用。TCB胁迫1—6d使活性氧清除酶功能紊乱,其中过氧化物酶(POD)活性升高,过氧化氢酶(CAT)活性开始上升后转为下降。推测大豆下胚轴受TCB胁迫伤害过程中,活性氧代谢失衡造成的膜脂质过氧化起着重要作用。

1,2,4-三氯苯胁迫对萌发大豆种子中活性氧的影响

以盆栽法研究了不同浓度 1,2 ,4 三氯苯 (TCB)胁迫对萌发大豆种子中活性氧代谢的影响 .结果表明 ,10 0～ 30 0 μg·g-1TCB胁迫初期 (1～ 3天 )促使萌发大豆种子呼吸强度升高及其峰值提前出现 ,超氧阴离子自由基 (O2 - )及过氧化氢 (H2 O2 )的积累显著增加 ,同时伴随丙二醛 (MDA)含量升高 ,显示发生膜脂质过氧化作用 .TCB胁迫 1～ 6天使活性氧清除酶功能紊乱 ,其中过氧化物酶 (POD)活性升高 ,超氧化物岐化酶 (SOD)活性开始上升后转为下降 .在萌发大豆种子受TCB胁迫伤害过程中 ,活性氧代谢失衡造成的膜脂质过氧化将起着重要作用 .

短期菲胁迫对大豆幼苗超氧化物歧化酶活性及丙二醛含量的影响

研究了不同浓度 ( 0～ 2 0 0 μg·g-1)菲胁迫和恢复培养后大豆幼苗生长、超氧化物歧化酶 (SOD)活性及丙二醛 (MDA)含量的变化 .结果表明 ,2 0 0 μg·g-1菲处理 5d后大豆幼苗生长受到抑制 ,但幼苗恢复培养后经短暂停滞期后仍可恢复生长 .菲污染对大豆幼苗SOD活性变化的剂量 效应关系的作用形式比较复杂 ,胁迫 2d时为线性关系 ,胁迫 5d和 8d时为抛物线型 .在菲处理前期 ( 2d) ,幼苗SOD活性被 10 0和2 0 0 μg·g-1菲显著诱导 [分别为对照的 1.15倍 (P <0 .0 5 )和 1.2 6倍 (P <0 .0 1) ].菲暴露 8d时 ,SOD活性显著降低 ,2 0 0 μg·g-1菲处理组SOD活性为对照的 88% (P <0 .0 5 ) .菲处理 5d后恢复培养 2d和 4d ,5 0和10 0 μg·g-1菲处理组幼苗SOD活性得到恢复 ,而 2 0 0 μg·g-1菲处理组幼苗SOD活性仍明显高于对照 (P <0 .0 5 ) .试验亦反映出 ,10 0和 2 0 0 μg·g-1菲处理 5d和 8d ,幼苗MDA含量均比对照显著增加 (P <0 .0 5和P <0 .0 1) .可以认为 ,SOD活性可作为大豆幼苗遭受短期菲胁迫的生物标记物 .

Characterization of structure and diffusion behaviour of Ca-alginate beads prepared with external or internal calcium sources

Ca-alginate beads were prepared with either external or internal calcium sources. The structures of both beads were investigated with the aid of scanning electron microscopy (SEM) and confocal microscopy. It was shown that the beads with internal calcium source had a looser structure and bigger pore size than those with external calcium source. The attempts to interpret the difference were carried out by determining the Ca content within the beads at various times, which indicated that it was the different gelation mechanisms that caused the difference of structures of both beads. Furthermore, it was also found that the diffusion rate of haemoglobin (Hb) within the beads with an internal calcium source was faster than that of the beads with an external one, which was consistent with the observation of their structures.

Microspheres and microcapsules, a survey of manufacturing techniques: Part III: Solvent evaporation

A methodological survey of microsphere formation and microencapsulation techniques based on solvent extraction/evaporation techniques is presented. Thus, basic features of solvent extraction and solvent evaporation processes, including droplet formation, droplet/particle stabilization, and solvent removal, are outlined. Preparation of a wide range of microspherical and microcapsular products based on biodegradable polyesters, polysaccharides, and nonbiodegradable polymers are discussed. Dependence of microcapsule characteristics on manufacturing parameters, as well as performance evaluation of microspherical and microcapsular products, are also briefly covered.

氯苯胁迫对蚕豆幼苗生长和细胞分裂的影响

研究了 1,2 ,4 三氯苯 (TCB)对蚕豆幼苗生长、根尖细胞分裂及染色体畸变的影响 .结果表明 ,随TCB浓度增加和处理时间延长 ,蚕豆幼苗根长的生长及根尖细胞有丝分裂指数降低甚至停止 .TCB诱发蚕豆根尖细胞有丝分裂过程中染色体数目畸变和结构畸变 .5 0～ 10 0 μg·g-1TCB胁迫 12～ 2 4h ,蚕豆根尖染色体的主要损伤形式为c 有丝分裂、染色体桥和不均匀排列 ,其出现百分率达 1.0 %～ 10 .3 % .30 0 μg·g-1TCB胁迫 12～ 96h ,蚕豆根尖细胞中染色体粘连 (S)、S +染色体断裂 (S +B)、S +染色体环 (S +R)、S +染色体不均匀排列 (S +A)及S +染色体桥 (S +Be)出现的百分率达 47.9%～ 88.9% ,各种类型染色体断裂出现的百分率仅为 18.1%～ 2 9.6 % ,说明蚕豆根尖细胞染色体畸变分析可作为TCB土壤污染监测的敏感生物监测指标 .

外源硒对大豆产量、植株氮磷含量及土壤酶活性的影响

利用盆栽试验 ,研究了不同浓度、不同价态外源Se对大豆产量、N、P含量及与N、P代谢密切联系的土壤脲酶和磷酸酶活性的影响 .结果表明 ,施用浓度为 0 .2 5和 0 .5 μg·g-1土的Se4+ 和Se6+ 后 ,大豆产量、含N量及土壤脲酶活性增加 ,大豆含P量和土壤磷酸酶活性降低 .当Se6+ 浓度为 0 .5 μg·g-1土时 ,大豆植株含N量与土壤脲酶活性呈极显著的抛物线相关关系 ;Se6+ 浓度为 0 .2 5 μg·g-1土时 ,大豆植株含P量与土壤磷酸酶活性呈极显著的抛物线相关关系 .Se4+ 处理的大豆N、P含量和土壤脲酶和磷酸酶活性均无显著相关关系 .

陕南土壤中水溶态硒、氟的含量及其在生态环境的表征

以陕南早古生代地层上发育的土壤为材料,研究土壤中水溶态硒、氟的含量及其与总量、土壤pH值之间的关系,探讨土壤水溶态硒、氟含量在生态环境中的表征作用.结果表明,陕南土壤中水溶态硒、氟的平均含量分别为0.012μg·g-1和0.87μg·g-1,土壤中水溶态硒、氟的含量同其总量之间都存在着显著的正相关关系;在供试土壤pH范围内(5.10—7.52),水溶态硒的含量随pH值的增加先降后升,水溶态氟随pH值的增减而同步增减,其相互间的关系均可用函数方程式定量表达.水溶态硒含量能较好地表征陕南的高硒生态环境,水溶态氟可作为生态系氟质量状况的一个指标,但其指示作用又囿于地域空间的限制.

大巴山区土壤中的硒和氟

以大巴山区典型早古生代地层上发育的自然土壤为对象,研究了大巴山区土壤中Se、F等生命元素的含量及分布规律。结果表明:大巴山区土壤中硒、氟的平均含量分别为665±1425μgg-1和670±451μgg-1,远高于对照和中国土壤背景值;富Zn贫Fe的土壤环境有利于Se、F的富集;土壤中硒、氟的含量受地层分布、母岩岩性等因素的控制,同时,表生地球化学作用、生物作用以及山地剥蚀地貌也影响它们在土壤中的重新分配。

Studies on the components of crude and processed Fructus Corni by ESI-MSn

The components of crude and processed Fructus Corni were investigated by means of electrospray ionization-tandem mass spectrometry(ESI-MSn) technique in the negative ion mode. Compared with those of crude Fructus Corni, the chemical components of the processed Fructus Corni were changed both in quality and in quantity. From the ESI-MS spectra of the crude and processed Fructus Corni, six peaks were selected to establish the characteristic ESI-MS peaks. Several factors in the processing procedure were examined.

Analysis on Iridoid Glycosides in Crude and Processed Extracts from Cornus Officinals by Liquid Chromatography-electrospray Ionization Mass Spectrometry

The iridoid glycosides in crude and processed extracts from cornus officinals have been analyzed by high performance liquid chromatography-electrospray ionization mass spectrometry. Samples were analyzed by a reversed-phase C18 column using a binary eluent under gradient conditions. Seven iridoid glycosides could be separated and detected. The [M-H](-) ions of iridoid glycosides in the negative ion mode were observed, which reflect their molecule mass information. An in-source collision induced dissociation (in-source CID) experiment was carried out in order to identify the structures and to measure the contents of iridoid glycosides. The epimers were discovered in the experiment for the first time, namely 7 alpha-O-ethyl-morroniside and 7 beta-O-ethylmorroniside.

Controlled Synthesis of Ln(3+) (Ln = Tb, Eu, Dy) and V5+ Ion-Doped YPO4 Nano-/Microstructures with Tunable Luminescent Colors

YPO4 nano/microcrystals with multiform crystal phases and morphologies, such as hexagonal nano/submicroprisms, spherical-like nanoparticles, and nanorods with different length/diameter ratios as well as tetragonal nanospindles, have been synthesized via a facile hydrothermal route. A series of controlled experiments indicate that the pH values in the initial solution, phosphorus sources, and the organic additive trisodium citrate (Cit(3-)) are responsible for crystal phase and shape determination of final products. It is found that Cit(3-) as a ligand and shape modifier has the dynamic effect by adjusting the growth rate of different facets under different experimental conditions, resulting in the formation of various geometries of the final products. The possible formation mechanisms for products with diverse architectures have been presented.

Tm3+ and/or Dy3+ doped LaOCl nanocrystalline phosphors for field emission displays

Blue, yellow and white light emissive LaOCl:Tm3+, LaOCl:Dy3+ and LaOCl: Tm3+, Dy3+ nanocrystalline phosphors were synthesized through the Pechini-type sol-gel process. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and cathodoluminescence (CL) spectra were used to characterize the samples. Under UV radiation (229 nm) and low-voltage electron beam (0.5-5 kV) excitation, the Tm3+-doped LaOCl phosphor shows a very strong blue emission corresponding to the characteristic transitions of Tm3+ (D-1(2), (1)G(4) -> F-3(4), H-3(6)) with the strongest emission at 458 nm. The cathodoluminescent color of LaOCl:Tm3+ is blue to the naked eye with CIE coordinates of x = 0.1492, y = 0.0684. This phosphor has better CIE coordinates and higher emission intensity than the commercial product Y2SiO5:Ce3+.

Nanocrystalline LaOCl:Tb3+/Sm3+ as promising phosphors for full-color field-emission displays

Nanocrystalline LaOCl:Tb3+/Sm3+ phosphors were synthesized by a Pechini-type sol-gel process. Under UV and electron-beam excitation, LaOCl:Tb3+/Sm3+ show the characteristic emission of Tb3+ (D-5(3,4) -> F-7(6), ... (2)) and Sm3+ ((4)G(5/2) -> H-6(5/2),(7/2),(9/2)), respectively. In particular, the cathodoluminescence (CL) color of LaOCl:Tb3+ can be tuned from blue to green by changing Tb3+-doped concentration, and their CL intensities (brightness) are higher than those of commercial products Y2SiO5:Ce3+ and ZnO:Zn, respectively. White CL can be realized by codoping with Tb3+ and Sm3+ in a single-phase LaOCl host. The obtained white light is very close to the standard white light. These phosphors are promising for application in field-emission displays.