北京东灵山地区地形土壤因子与植物群落关系研究

 地形与土壤因子是决定植物群落结构的主要因素,同时植物多样性在不同尺度上影响着景观中的流,植物、地形与土壤三者之间在不同尺度上密切联系,研究它们之间的关系对于了解生态系统功能过程非常重要。针对东灵山地区异质化景观现状,在小流域尺度上选取了76个20 m×20 m的样地进行调查,研究选取了16个指标,分别代表地形因子、植物群落与土壤性质。利用多元统计手段,对选取指标进行了主成分分析、聚类分析与典范相关分析。结果显示土壤、植被、地形因子三者相互影响：地形因子与土壤理化性质影响着植被的分布格局与群落结构,反过来群落因子也对土壤的理化因子产生较大的影响。土壤有机质含量是指示土壤肥力的一个敏感指标,3种不同肥力类型中,群落的层盖度与丰富度存在较大的差别,而决定其分布的地形特点也不相同。不同指标集团的典范相关分析表明,坡位主要影响乔木层盖度,海拔高度与全氮相关性密切,而乔木层物种丰富度与有机质含量关系密切。     

抗IBDV独特型抗体杂交瘤细胞株的建立及其产物生物学特性测定

用纯化的抗IBDV IgG免疫Balb/c小鼠,取其脾细胞与SP2/0细胞在聚乙二醇（PEG）作用下融合,ELISA法检测筛选,经有限稀释法克隆3次,获得2株（5F₄株,2B₆株）分泌抗IBDV独特型抗体的杂交瘤细胞株,其能诱生Balb/c小鼠产生ELISA抗体效价分别为1∶12 800和1∶25 600的含抗IBDV独特型抗体的腹水。用此独特型抗体与福氏完全佐剂和福氏不完全佐剂乳化制备成抗IBDV独特型抗体疫苗,免疫接种SPF鸡和普通京白公鸡,然后用IBDV强毒株(SD株)2000 ELD50攻毒,SPF鸡免疫组50只,有5只发病、2只死亡;对照组10只全部发病,8只死亡。普通京白鸡免疫组30只,有7只发病, 1只死亡;对照组10只全部发病,6只死亡。经X²检验,SPF鸡X²＝34.15,普通鸡X²＝16.68,查X²值表得X²_(1)0.01＝6.63, SPF鸡X²和普通鸡X2均大于X²_{(1) 0.01}（P＜0.01）,由此表明抗IBDV独特型抗体疫苗具有很好的免疫原性,对易感日龄的SPF鸡和普通鸡均具有极其明显的保护作用。从而证实了抗IBDV独特型抗体疫苗有潜在的研究和应用价值。     

Weighted Wilcoxon-type smoothly clipped absolute deviation method

Summary .  Shrinkage-type variable selection procedures have recently seen increasing applications in biomedical research. However, their performance can be adversely influenced by outliers in either the response or the covariate space. This article proposes a weighted Wilcoxon-type smoothly clipped absolute deviation (WW-SCAD) method, which deals with robust variable selection and robust estimation simultaneously. The new procedure can be conveniently implemented with the statistical software R . We establish that the WW-SCAD correctly identifies the set of zero coefficients with probability approaching one and estimates the nonzero coefficients with the rate   n ^−1/2  . Moreover, with appropriately chosen weights the WW-SCAD is robust with respect to outliers in both the x and y directions. The important special case with constant weights yields an oracle-type estimator with high efficiency in the presence of heavier-tailed random errors. The robustness of the WW-SCAD is partly justified by its asymptotic performance under local shrinking contamination. We propose a Bayesian information criterion type tuning parameter selector for the WW-SCAD. The performance of the WW-SCAD is demonstrated via simulations and by an application to a study that investigates the effects of personal characteristics and dietary factors on plasma beta-carotene level.     

Hydrothermal synthesis, crystal structure and magnetic characterization of three hexa-M substituted tungstoarsenates (M = Ni, Zn and Mn)

Three novel hexa-transition-metal complexes substituted tungstoarsenates, [Ni₆(imi)₆(B-α-H₃AsW₉O₃₃)₂]·2H₂O (1), [Zn₆(imi)₆(B-α-H₃AsW₉O₃₃)₂]·2H₂O (2) and [Mn₆(imi)₆(B-α-H₃AsW₉O₃₃)₂]·4H₂O (3) (imi = imidazole), have been synthesized hydrothermally without using any polyoxoanion as precursor and characterized by elemental analyses, IR, TG and X-ray single-crystal diffraction. Compounds 1-3 are isostructural, composed of [B-α-H₃AsW₉O₃₃]¹²⁻ anions and [M₆(imi)₆]¹²⁺ complex cations (M = Ni, Zn and Mn), all M atoms are square pyramidal geometry, and held together to form hexagonal metallocycles by edge-sharing oxygen atoms. In compounds 2 and 3, [M₆(imi)₆(B-α-AsW₉O₃₃)₂] (M = Zn, Mn) segments act as 12-connected nodes to form complicated 3D network via hydrogen-bonding interactions, respectively. Magnetic measurements for 1 show the presence of ferromagnetic interactions within the hexanuclear Ni²⁺ cations.     

Synthesis, structures and magnetic properties of nickel(II), manganic(II) and zinc(II) complexes containing pyridyl-substituted nitronyl nitroxide and tris(2-benzimidazolymethyl)amine

Three new magnetic compounds were synthesized by using 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (NIT2Py) and tris(2-benzimidazolymethyl)amine (NTB) as ligands. The structures and magnetic properties of the complexes with formula [Ni(NIT2Py)(NTB)](ClO₄)₂(CH₃OH) 1, [Mn(NIT2Py)(NTB)](ClO₄)₂2 and {[Zn(NIT2Py)₂(CH₃OH)₂](ClO₄)₂}{[Zn(NTB)(H₂O)](ClO₄)₂} 3 were characterized. Compounds 1 and 2 both have [M(NIT2Py)(NTB)] structural units, where the metal ion is in an octahedral environment bound to one NIT2Py through one pyridyl nitrogen atom and one nitroxide oxygen atom. However, compound 3, the chelating zinc ion has two crystallographically independent molecules in the asymmetric unit: one is six coordinated octahedral structure [Zn(NIT2Py)₂(CH₃OH)₂](ClO₄)₂, and the other one is five coordinated pyramidal structure [Zn(NTB)(H₂O)](ClO₄)₂. The magnetic behaviors of these compounds indicate that both the nickel ion and the manganese ion are antiferromagnetically coupled with the NIT2Py ligand with a coupling constant of −19.44 and −0.37 cm⁻¹, respectively, whereas two NIT2Py ligands in compound 3 are ferromagnetically coupled with a coupling constant of 19.1 cm⁻¹.     

Synthesis, crystal structure and magnetic properties of a one-dimensional Mn(III) Schiff-base complex bridged by derivative of tetracyano-p-quinodimethane

A new one-dimensional manganese(III) Schiff-base complex [Mn(III)(salophen) (MeOTCNQ)] · CH₃CN 1 (salophen = N,N′-bis(salicylidene)phenylenediamine) bridged by 7-methoxy-7,7,8,8-tetra-cyano-p-quinodimethane (MeOTCNQ), has been synthesized and characterized by X-ray crystallography and magnetic studies. Crystal structure study reveals that complex 1 has a 1D manganese(III) chain bridged by MeOTCNQ ligand which was obtained unexpectedly from tetracyano-p-quinodimethane (TCNQ) reacting with methanol. Noticeably, MeOTCNQ molecules in complex 1 adopt an unusual cis-syn coordination mode. The analysis of magnetic data indicates that a weak intrachain antiferromagnetic interaction exists in complex 1.     

Liquid state machines and cultured cortical networks: the separation property

In vitro neural networks of cortical neurons interfaced to a computer via multichannel microelectrode arrays (MEA) provide a unique paradigm to create a hybrid neural computer. Unfortunately, only rudimentary information about these in vitro network's computational properties or the extent of their abilities are known. To study those properties, a liquid state machine (LSM) approach was employed in which the liquid (typically an artificial neural network) was replaced with a living cortical network and the input and readout functions were replaced by the MEA-computer interface. A key requirement of the LSM architecture is that inputs into the liquid state must result in separable outputs based on the liquid's response (separation property). In this paper, high and low frequency multi-site stimulation patterns were applied to the living cortical networks. Two template-based classifiers, one based on Euclidean distance and a second based on a cross-correlation were then applied to measure the separation of the input-output relationship. The result was over a 95% (99.8% when nonstationarity is compensated) input reconstruction accuracy for the high and low frequency patterns, confirming the existence of the separation property in these biological networks.     

Efficient constitutive expression of chitinase in the mother cell of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> and its potential to enhance the toxicity of Cry1Ac protoxin

Previous studies revealed that chitinase could enhance the insecticidal activity of Bacillus thuringiensis and it has been used in combination with B. thuringiensis widely. However, the expression of B. thuringiensis chitinase is rather low and needs induction by chitin, which limits its field application. It would make sense to constitutively express the chitinase at a sufficiently high level to offer advantages in biological control of pests. In this study, a signal peptide-encoding sequence-deleted chitinase gene from B. thuringiensis strain 4.0718 under the control of dual overlapping promoters plus Shine–Dalgarno sequence and terminator sequence of cry1Ac3 gene was cloned into shuttle vector pHT315 and introduced into an acrystalliferous B. thuringiensis strain Cry⁻B. The recombinant plasmid was stably maintained over 240 generations in Cry⁻B. Chitinase was overexpressed within the sporangial mother cells in the form of spherical crystal-like inclusion bodies. The chitinase inclusions could be solubilized and exhibit chitinolytic activity in 30 mmol l⁻¹ Na₂CO₃–0.2% β-mercaptoethanol buffer at a wide range of alkaline pH values, and what’s more, the chitinase inclusions potentiated the insecticidal effect of Cry1Ac protoxin when used against larvae of Spodoptera exigua and Helicoverpa armigera.     

麻疯树种油的理化性质及籽粕中元素含量分析及其应用价值初探

麻疯树(Jatropha curcas L. )为大戟科(Euphorbiaceae)麻疯树属(Jatropha L. )植物,果实含油量高,种仁含油量在60%左右,可用于加工提炼优质生物柴油,以替代日益紧缺的石油能源~([1-2]).近年来,由国家科学技术部和联合国开发计划署共同开展的绿色扶贫项目中,麻疯树已经在中国石漠化最为严重的贵州、四川及云南等省区试种成功.麻疯树全株有毒,其种子、树皮、叶、根和乳汁中含有多种化学成分,可作为医药和生物农药资源;其种子加工后残留的油饼中蛋白质含量较高,可作为优质肥料,经脱毒后也可作为饲料~([3]).     

灰绿曲霉β-葡萄糖苷酶的分离及特性

目的：利用灰绿曲霉EU7-22发酵产纤维素酶,从中分离到β-葡萄糖苷酶,分析其理化特性,确定其最佳活性条件。方法：灰绿曲霉EU7-22发酵液离心后,上清液经硫酸铵沉淀、Phenyl 6 Fast Flow（highsub）疏水层析和Sephacryl S-200凝胶层析,获得纯化的β-葡萄糖苷酶。结果：纯酶的比活性为5.1 IU/mg,得率为13.89%。SDS-PAGE凝胶电泳分析表明该酶是单亚基蛋白,其分子量为56.2 kDa。在pH4.0~6.0范围内,β-葡萄糖苷酶具有较高的稳定性,该酶的最适酶促反应pH为5.0。当β-葡萄糖苷酶在温度低于60℃的缓冲液中温育1 h后,酶活损失不大,表现了较好的稳定性;当该酶在温度高于60℃的缓冲液中温育1 h后,酶活迅速丧失。β-葡萄糖苷酶在70℃时具有最大催化活性。结论：灰绿曲霉EU7-22发酵产生的β-葡萄糖苷酶具有较高活性,具有分子量较小、最佳催化温度较高的特点。