森林草原过渡带中沙地云杉幼苗在林窗中的环境梯度变化(英文)

在我国内蒙古自治区森林草原过渡带中,从林窗内到周围环境进行沙地云杉(Piceamongolica)幼苗的调查以阐明其梯度变化。在沙地森林区,选择了一个形成年龄长达30年的大林窗,从林窗中央向周围森林作2个5m宽的样带,对沙地云杉幼苗动态进行了监测。幼苗距离林窗中心越远,个体越高,数量也越多。在林窗内,有很多幼苗,但是大多数的幼苗在它们长大之前就死亡了。相对于林木高度的动态变化,幼苗的死亡率在样带中的分布基本上有着相似的规律。沿着森林的边缘,幼苗的生长可能由于林窗中边缘光线渗透而得到暂时的提高。文中还讨论了自然森林的更新动态。结果表明在沙地云杉林里林窗干扰带能产生一个非均质的环境促进物种的更新,从而决定了该森林是一个多年龄层次的森林类型。图6参37。

沈阳市城区土壤和灰尘中铅的分布特征

对沈阳市城市土壤和灰尘中铅的分布特征进行了研究.结果表明,沈阳市区土壤中全铅含量为26~2910.60mg/kg,平均为199.72mg/kg,是对照(33.30mg/kg)的6倍,是沈阳市土壤背景值(22.15mg/kg)的9倍;沈阳市区灰尘中铅浓度范围为19.58~2809.90mg/kg,平均为220.06mg/kg,是对照(37.97mg/kg)的5.8倍;沈阳市土壤和灰尘中铅分布空间差异大,局部污染比较严重,灰尘中铅与土壤中铅的分布规律趋于一致,铁西区铅浓度最高,其次是和平区、皇姑区和于洪区的交界处以及大东工业区;土壤和灰尘中铅含量与距污染源的距离成反比,与距地表的距离也成反比.

生物有机肥对西红柿生长及品质影响效应初探

在西红柿上进行施用生物有机肥、有机无机配合施肥、三元肥的田间对比试验。结果表明,单施生物有机肥比单施无机三元肥的西红柿中硝酸盐含量低15.71%,维生素C含量高25.82%;种植后土壤中有机质含量提高11.21%。西红柿种植中施用生物有机肥可以提高西红柿品质,减轻病害,增加土壤中有机质含量,培肥地力;生物有机肥与无机三元肥配合施用与单施无机肥料间产量差异不大。

水肥耦合对春小麦水分利用效率的影响

采用312-D最优饱和设计,在辽西半干旱区开展了连续4年的春小麦田间水肥耦合试验,研究春小麦水分利用效率。结果表明:水肥单因子对水分利用效率有显著影响,影响顺序为:水>磷>氮。其中,氮、磷施用量对水分利用效率的提高是正效应,而灌水量对水分利用效率是负效应。水肥多因子对水分利用效率有交互效应,氮与磷之间、氮与水之间的交互效应极显著,对水分利用效率表现为正效应。磷与水之间表现为负效应,但不显著。水分利用效率超过10kg/(hm2·mm)的水肥优化管理方案为,施氮量102 6～239 3kg/hm2,施磷量84 3～139 0kg/hm2,灌水量41 0～170 9mm。获得最大水分利用效率的施氮量220 6kg/hm2,施磷量76 0kg/hm2,灌水量117 4mm。

中巴地球资源卫星在辽东区域环境监测中的应用评价研究

对中巴资源一号卫星 CCD传感器接收的辽宁省营口幅数据 ,从几何精度、空间分辨率、数据噪声等方面 ,进行了图像数据质量评价 ,认为从总体上讲 ,达到了设计要求 ,具有广阔的应用前景 ,同时指出 ,CCD传感器在稳定性和同一性方面尚需改进

Use of Ecosystem Flux Data and a Simulation Model to Examine Seasonal Drought Effects on a Subtropical Coniferous Forest

National Natural Science Foundation of China (NSFC) [30670384, 30590381]

厚壁和薄壁碳纳米管载Pt催化剂制备和对甲醇氧化的电催化活性

制备了壁厚约5 nm、管径为140~220 nm薄壁碳纳米管(CNTs)和壁厚约50 nm,管径为80~200 nm厚壁碳纳米管。研究了浓HNO3处理对不同壁厚CNTs结构和表面基团的影响。结果表明,经硝酸处理后,厚壁CNTs的双电层充放电电量(Qd)和表面含氧基团氧化所需电量(Qo)分别增加了1.34和0.098 mC,薄壁CNTs的Qd和Qo分别增加了5.69和0.175 mC。表明与厚壁CNTs相比,薄壁CNTs易被切断,表面碳原子易被氧化。当用常规液相还原法将Pt粒子沉积在薄壁和厚壁CNTs上后,由于浓HNO3处理过的薄壁CNTs具有大的比表面积和多的含氧基团,Pt粒子更容易均匀的吸附在薄壁CNTs表面,因此,制得的Pt/CNTs催化剂对甲醇氧化有很高的电催化活性。

The investigation of exfoliation process of organic modified montmorillonite in thermoplastic polyurethane with different molecular weights

Cloisite 30B (30B) was melt-mixed with two kinds of thermoplastic polyurethane (TPU) with different molecular weights to discern the roles of molecular diffusion and shear in the exfoliation process. The higher level of exfoliation was achieved in TPU matrix with higher molecular weight due to the appropriate viscosity. In order to have an insight into the mechanism of exfoliation, the degree of dispersion and exfoliation of 30B was characterized by wide angle X-ray diffraction and transmission electron microscopy. The layers of 30B were exfoliated via a slippage process, which was also observed in polyamide 12 nanocomposites recently.

Characterization of High Melt Strength Polypropylene Synthesized via Silane Grafting Initiated by In Situ Heat Induction Reaction

High melt strength polypropylene (HMSPP) was synthesized by in situ heat induction reaction, in which pure polypropylene (PP) powders without any additives were used as a basic resin and vinyl trimethoxysilane (VTMS) as a grafting and crosslinking agent. The grafting reaction of VTMS with PP was confirmed by FTIR. The structure and properties of HMSPP were characterized by means of various measurements. The content of grafted silane played a key role on the melt strength and melt flow rate (MFR) of HMSPP. With increasing the content of grafted silane, the melt strength of HMSPP increased, and the MFR reduced. In addition, due to the existence of cross-linking structure, the thermal stability and tensile strength of HMSPP were improved compared with PP.

Effects of Y2O3 addition on the phase evolution and thermophysical properties of lanthanum zirconate

Lanthanum zirconate (La2Zr2O7, LZ) powders with the addition of various Y2O3 contents for potential thermal barrier coatings (TBCs) application were synthesized by solid-state reaction. The structure evolution, sintering-resistance and thermophysical properties of the synthesized powders and sintered ceramics were systematically studied. X-ray diffraction (XRD) results indicate that LZ containing 3-12 wt.% Y2O3 mainly keeps a pyrochlore-type structure, and two new phases of LaYO3 and Y0.18Zr0.82O1.91 are also detected. Raman spectra confirm that the higher the Y2O3 content, the easier is the formation of LaYO3.

Chiral Salan Aluminium Ethyl Complexes and Their Application in Lactide Polymerization

Synthetic routes to aluminium ethyl complexes supported by chiral tetradentate phenoxyamine (salan-type) ligands [Al(OC6H2(R-6-R-4)CH2)(2){CH3N(C6H10)NCH3}-C2H5] 7: R = H ; 5, 8: R = Cl; 6, 9: R = CH3) are reported. Enantiornerically pure salan ligands 1-3 with (R,R) configurations at their cyclohexane rings afforded the complexes 4, 5, and 6 as mixtures of two diastereoisomers (a and b). Each diastereoisomer a was, as determined by X-ray analysis, monomeric with a five-coordinated aluminium central core in the solid state, adopting a cis-(O,O) and cis-(Me,Me) ligand geometry. From the results of variable-temperature (VT) H-1 NMR in the temperature range of 220-335 K, H-1-H-1 NOESY at 220 K, and diffusion-ordered spectroscopy (DOSY), it is concluded that each diastereoisomer b is also monomeric with a five-coordinated aluminium central core.

Effect of Zn concentration on the microstructures and mechanical properties of extruded Mg-7Y-4Gd-0.4Zr alloys

Microstructures and mechanical properties of the Mg-7Y-4Gd-xZn-0.4Zr (x = 0.5, 1.5, 3, and 5 wt.%) alloys in the as-cast, as-extruded, and peak-aged conditions have been investigated by using optical microscopy, scanning electron microscope, X-ray diffraction, and transmission electron microscopy. It is found that the peak-aged Mg-7Y-4Gd-1.5Zn-0.4Zr alloys have the highest strength after aging at 220 A degrees C. The highest ultimate tensile strength and yield tensile strength are 418 and 320 MPa, respectively. The addition of 1.5 wt.% Zn to the based alloys results in a greater aging effect and better mechanical properties at both room and elevated temperatures. The improved mechanical properties are mainly ascribed to both a fine beta' phase and a long periodic stacking-ordered structure, which coexist together in the peak-aged alloys.

Preparation and chracaterization of novel graft copolymers of LLDPE

A series of novel fluorine surfactants, a, b, c, d, e and their acrylates, A, 13, C, D and E, were synthesized via poly( ethylene oxide) ( PEG) ( 200, 600, 1000, 2000, 5000) and perfluorooctane poly (ethylene oxide) ether as the main starting materials. Their chemical structures were characterized by means of FTIR and H-1 NMR. The surface activity and surface tension( y) of surfactants a, b, c, d and e were evaluated by maximum bubble pressure method. Surfactants A, 13, C, D and E were adopted as the grafting monomers of linear low density polyethere( LLDPE), and grafting reaction was carried out by melt reactive extrusion procedure. Their surface properties were characterized with measuring contact angle and XPS. It was found that the hydrophilic property of the graft copolymers was better than the palin LLDPE. Thermal properties of graft copolymers were studied by DSC. It was found that their crystalline temperatures of graft copolymers were faster than that of the plain LLDPE.

Synthesis and electrical properties of new solid state. Electrolyte materials Ce5.2RE0.8MoO15-delta

A series of solid state electrolytes, Ce-5.2 RE0.8 MoO15-delta (RE = Y, La, Sm, Gd, Dy, Ho, Er), were synthesized by sol-gel method. Their structures and electrical conductivities were characterized by X-ray Diffraction (XRD), Raman and X-ray Photoelectron Spectroscopy (XPS) and AC impedance spectroscopy, respectively. The results show that the concentrations of oxygen vacancy increased with increasing x and their conductivity were improved. And the cell parameters increase as the radius of RE3+ increases. Because the ionic radius of doped Dy3+ (0.0908 nm) is closed to that of Ce4+ (0.0920 nm), their oxide has minimal cell elastic straining between RE3+ and oxygen vacancy, and the system has the least association enthalpy, thus the oxide Ce-5.2 Dy-0.8 MoO15-delta exhibits a higher conductivity (7.02 x 10(-3) S/cm) and lower activation energy (1.056 eV) compared to the other doped compounds.