黄土高原半干旱区集流灌草立体配置与水分调控

该区干旱与水土流失并存 ,降雨量时空分配不均 ,且水热并不同步 (在春夏 ,植物常因缺水而枯死 ) ,致使生态环境建设中恢复植被的难度大。为此 ,采用工程整地措施与灌草立体配置模式 ,发展集流灌草植被 ,调蓄土壤水分 ,促进灌草植被的快速恢复。结果表明 ,在水平阶营造柠条和披碱草 ,在生长初期 0～ 50 0 cm土层含水量可分为 3个明显的层次 ;在生长的第 4年随着灌草根系深扎 ,土壤水分过耗 ,出现明显的干土层 ,分布深度在 1 2 0～ 2 0 0 cm,厚度为 1 0 0 cm。在第 8年干土层扩大到 1 0 0～ 30 0 cm,厚度为 2 0 0 cm。第 1 4年土壤含水量有所回升 ,但幅度不大 ,同第 8年相比 ,仅提高 1 .5～ 2 .0个百分点。水平阶的柠条灌木林随着生长时间的延续 ,其水分贮量变化是否增加 ,仍有待继续研究。该区 0～ 50 0 cm多年土壤贮水量 ,在生长初期 ( 4月份 ) ,1 5年生柠条480 .1 5mm,1 2年生沙棘、山桃分别为 41 4.6mm和 385.4mm,在生长末期 ( 1 0月 ) ,柠条 498.31mm,沙棘 42 3.31 mm,山桃 ...

热解吸-气相色谱法测定植物源挥发性有机物

以Tenax-TA、Carboxen 1000和Carbosieve SⅢ为采样管填充料,将植物源挥发性有机物吸附于采样管内,样品通过二次热解吸仪解吸后,随载气进入气相色谱仪,采用氢火焰离子化检测器(FID)测定,建立了利用二次热解吸仪与气相色谱联用技术测定植物挥发性有机物的分析方法。载气N2流速为30 mL/min,60℃下吹扫吸附管2 min,然后在250℃下解吸吸附管5 min,冷却1 min后,在275℃下解吸聚焦管3 min,样品经传输线进入气相色谱。气相色谱载气N2压力为190 kPa,FID检测器温度280℃;进样口温度225℃;初始柱温40℃,停留5 min,以2℃/min升温至120℃,保留1 min,然后以20℃/min升温至200℃,保留10 min。方法重现性好,精密度高,线性相关系数大于0.99;检出限均低于9×10-9g/L;解吸效率大于96%,适用于植物源挥发性有机物的测定。

类肝素化合物的傅立叶变换离子回旋共振-电喷雾质谱研究

采用负离子模式的电喷雾傅立叶变换离子回旋共振质谱(ESI-FTICR-MS)对3个合成的肝素类化合物DHα、THα和THβ进行了全扫描一级谱和持续非共振辐照碰撞诱导解离(SORI-CID)串联质谱分析。样品浓度10μmol/L,流动泵注射直接进样。化合物中的磺酸胺和磺酸酯结构容易在一般电喷雾条件下发生分解,失去一个或者多个SO3,一级全扫描谱图中得到的谱峰均是带有单电荷或者双电荷的准分子离子峰。

Gold nanoparticle-based surface enhanced Raman scattering spectroscopic assay for the detection of protein-protein interactions

In the present work, a sensitive spectroscopic assay based on surface-enhanced Raman spectroscopy (SERS) using gold nanoparticles as substrates was developed for the rapid detection protein-protein interactions. Detection is achieved by specific binding biotin-modification antibodies with protein-stabilized 30 nm gold nanoparticles, followed by the attachment of avidin-modification Raman-active dyes. As a proof-of-principle experiment, a well-known biomolecular recognition system, IgG with protein A, was chosen to establish this new spectroscopic assay. Highly selective recognition of IgG down to 1 ng/ml in solution has been demonstrated.

Comparative study of PHBV/TBP and PHBV/BPA blends

In order to clarify the effects of phenols on properties of polyesters, the blends of poly[(3-hydroxybutyrate)-co-(3-hydroxyvalerate)] (PHBV) with 4,4'-dihydroxydiphenylpropane (BPA) and p-tert-butylphenol (TBP) were studied. The FTIR spectra revealed that there was strong hydrogen-bond (H-bond) interaction between PHBV and both phenols. By evaluating the fraction of H-bonded C = O in the blend, it was concluded that BPA showed a stronger tendency than TBP to form H-bonds with PHBV. Accordingly, BPA formed a stronger suppression than TBP on the crystallization of PHBV. When 30 wt% BPA or 50 wt% TBP were added into PHBV, the crystallization of PHBV was completely suppressed in the DSC cooling scan. As the phenol content was increased, the T-g of PHBV/TBP blend decreased while the T-g of PHBV/BPA blend increased. This difference indicated that TBP and BPA acted as plasticizer and physical crosslinking agent, respectively.

Structure and identity of 4,4 '-thiobisbenzenethiol self-assembled monolayers

Self-assembled monolayers (SAMs) of 4,4'-thiobisbenzenethiol (TBBT) can be formed on Au surface spontaneously. The structural characteristics and adsorption behavior of TBBT SAMs on Au have been investigated by surface enhanced Raman scattering (SERS), electrochemical cyclic voltammetry (CV), ac impedance spectroscopy (EIS), and atomic force microscopy (AFM). It is demonstrated that TBBT adsorbed on Au by losing a H atom, forming one Au-S bond, and the other mercapto group is free at the surface of the monolayer owing to the presence of the nu(S-H) at 2513 cm(-1) and the delta(C-S-H) at 910 cm(-1) in SERS. The enhancement of the vibration of C-S (1064 cm(-1)), the aromatic C-H vibration (3044 cm(-1)), and the absence of the vibration of S-S illustrate TBBT adsorbed on Au forming a monolayer with one benzene ring tilted with respect to the Au surface. The interpretation of the observed frequencies is aided by ab initio molecular orbital (MO) calculations at the HF/6-31G* level of theory. Electrochemical CV and EIS indicate TBBT monolayers can passivate the Au effectively for its low ratio of pinhole defects (theta = 99.6%). AFM studies give details about the surface morphology. The applications of TBBT SAMs have been extensively investigated by exposure of Cu2+ ion to TBBT SAMs on Au and covalent adsorption of metal nanoparticles.

The structural transition of DNA-Tris(1,10-phenanthroline) cobalt(III) complexes in ethanol-water solution

The interaction of DNA with Tris(1,10-phenanthroline) cobalt(III) was studied by means of atomic force microscopy. Changes in the morphologies of DNA complex in the presence of ethanol may well indicate the crucial role of electrostatic force in causing DNA condensation. With the increase of the concentration of ethanol, electrostatic interaction is enhanced corresponding to a lower dielectric constant. Counterions condense along the sugar phosphate backbone of DNA when e is lowered and the phosphate charge density can thus be neutralized to the level of DNA condensation. Electroanalytical measurement of DNA condensed with Co(phen)(3)(3+) in ethanol solution indicated that intercalating reaction remains existing. According to both the microscopic and spectroscopic results, it can be found that no secondary structure transition occurs upon DNA condensing. B-A conformation transition takes place at more than 60% ethanol solution.

抗坏血酸自加速的圆二色谱电化学研究

以现场长光程薄层圆二色光谱电化学方法研究了抗坏血酸在玻碳电极上的电极反应过程.通过双对数法和非线性回归的方法处理了薄层圆二色光谱电化学实验数据,结果表明抗坏血酸在pH7.0的缓冲溶液中玻碳电极上为2个电子转移的不可逆电化学氧化,氧化产物在电极上发生了强吸附,吸附层对抗坏血酸的电化学氧化反应有自加速作用,并获得了抗坏血酸在探电极和在吸附电极上的式电位分别为E~(?)=0.09V,E~(?)=0.26V;电子转移数和电子转移系数分别为an=0.41,a_(?)n=0.07;标准复相电子转移速率常数分别为k~0=8.0×10~(-5)cm s~(-1),k~0_a=1.9×10~(-4)cm s~(-1);吸附系数为β=102.6±0.2.

Syntheses and structures of Na-2[Zn-II(ida)(2)].7H(2)O and Na-4[Hg-II(nta)(2)].7H(2)O

The title complexes were synthesized and the crystal structures of their salts were determined by single-crystal X-ray structure analyses. Na-2[Zn-I(ida)(2)]. 7H(2)O: Triclinic, P1, a=0.523 4(2) nm, b=0.897 10(10) nm, c=1.069 10(10) nm, alpha=85.910(10)degrees, beta= 76.380(10)degrees, gamma=83.52(2)degrees, V=0.484 2(2) nm(3), Z=1. The complex anion [Zn-I (ida)(2)](2-) has a pseudo-octahedral structure in which the two N atoms: are in a trans configuration. Na-4[Hg-I(nta)(2)]. 7H(2)O: Monoclinic, C-c, a = 1.795 0(4) nm, b = 0.892 9(2)nm, c = 1.575 4(2) nm, beta = 92.78 (3)degrees, V = 2.526 2(9) nm(3), Z = 4. The complex anion [Hg-I (nta)(2)](4-) has a pseudo-bicapped-octahedral structure in which the two N atoms are in a trans configuration.

用毛细管电泳研究不同形态的砷

本文用高效毛细管电泳在中性、碱性缓冲溶液中研究了不同价态、形态的砷，考察了pH，不同介质对形态的影响，波长对不同形态砷的响应信号影响，测定了H2AsO-4，H2AsO-3的检测下限。

Nafion-玻碳修饰电极阴极溶出伏安法测定痕量铋的研究

研究并提出在HNO_3-NaCl-硫脲(Tu)体系中,Nafion/玻碳(Gc)修饰电极阴极溶出伏安法测定痕量鉍的方法。表明Tu具络合协同作用,使Nation阳离子交换能力提高。本法检出限为5×10~(-9)mol/L Bi~(3+)(td:5min),电极表面易于再生,文中研究了电极过程机理,计算得[Bi(Tu)_6]~(3+)在Nafion膜中的分配系数(K_D),扩散系数(D)和选择性系数(K_H~[Bi(Tu)_6~+]~(3+))分别为7.57×10~5,5.9×10~(-11)cm~2/s及3.39。

钐的氟化物体系中钐离子价态及其转换

H_2气流中多次还原SmF_3,合成了非整比系列SmF_x(2.0≤x≤3.0),并获得了接近整比的二氟化钐,讨论了各类非整比氟化钐化合物的结构及钐离子的价态,考察了在不同气氛中二氟化钐中钐离子价态的高温转换过程。

中性载体ETH1117推动H~+通过水/硝基苯界面传递的电化学研究

用循环伏安法研究中性载体ETH1117推动H~+通过水/硝基苯界面的转移。通过络合使H~+穿过水/硝基苯界面转移,是受扩散控制的可逆过程,ETH1117与H~+在硝基苯相的配合比为1:1,配合物的稳定常数β_0为2.9×10~7,扩散系数D为4.2×10~(-6)cm~2/s。