Determination of volatile compounds in foliage of Fraser fir (Abies fraseri) and balsam fir (Abies balsamea)

The Fraser fir (Abies fraseri) and balsam fir (Abies balsamea) are eastern North American conifers which have been infested by an exotic insect, the balsam woolly adelgid (BWA). BWA infestation has had particularly severe effects on Fraser fir, with up to 95% mortality rates at some sites, and is characterized by attack on mature trees only. The purpose of this research was to perform a chemosystematic study to evaluate whether differences in volatile chemical concentrations of various stands of fir were observed as a function of resistance to BWA infestation. The concentrations of volatiles were determined by a methylene chloride extraction procedure, followed by analysis by gas chromatography. First, comparisons were made of concentration levels of volatiles in Fraser and balsam fir foliage of seedlings, saplings, and mature trees. If a chemical provided resistance, one would expect higher volatile levels in the balsam foliage because of its greater resistance to BWA. Second, the volatile levels in Fraser fir saplings and mature trees at uninfested sites were compared to the levels in surviving Fraser fir saplings and mature trees at infested sites. For a compound that provided BWA-resistance, higher volatile levels would be expected at the infested site because of the greater resistance of the surviving trees. Lastly, the concentrations of volatiles in sapling foliage were compared to those in mature foliage, where higher levels of resistance-providing chemicals would be expected in the saplings. 3-Carene was shown to consistently follow the expected pattern for a compound that provides resistance against BWA and β-pinene followed the pattern for the majority of the comparisons. These results indicate that while maltol and total volatiles did not correlate with the expected pattern, 3-carene, and possibly β-pinene and sesquiterpenes may provide fir with defense against BWA infestation.     

Solid phase microextraction for the determination of volatile organics in the foliage of Fraser fir (Abies fraseri)

Solid phase micro extraction (SPME) was investigated for the determination of volatile chemicals in the foliage of Fraser fir (Abies fraseri). Advantages of SPME include its speed, sensitivity, and ability to determine volatiles without chemical solvents. In this study, qualitative comparisons were performed of the volatiles emitted from living foliage (in situ), damaged living foliage (in situ damaged), and severed foliage (ex situ). These studies suggest that β-phellandrene and γ-terpinene may be emitted as a response to foliar injury. Comparisons were made of the volatiles collected by SPME with ex situ sampling to previous studies in our laboratory using methylene chloride extraction. Similar results were obtained by the two extraction methods.     

Determination of Aluminum, Calcium, and Magnesium in Fraser Fir, Balsam Fir, and Red Spruce Foliage and Soil from the Southern and Middle Appalachians

Spruce–fir forests form unique ecosystems in the eastern United States and Canada. These forests are composed of Fraser fir (Abies fraseri) and red spruce (Picea rubens) in the Southern Appalachians, and balsam fir (Abies balsamea) and red spruce in the middle and northern Appalachians. Decline of spruce–fir forests has been observed since the 1960s that has been attributed, at least in part, to acidic deposition. Acidic deposition has been reported to decrease the availability of calcium and increase the availability of aluminum and induce decline of red spruce at high elevation sites above 1800 m. Aluminum, calcium, and magnesium were determined in Fraser fir, balsam fir, and red spruce foliage and soil from sites in the southern and middle Appalachians in order to evaluate whether acidic deposition may play a role in the decline of the conifers. Our nutrient studies did not provide any evidence that acidic deposition was affecting the conifers.     

连翘酯苷A与弹性蛋白酶相互作用的研究

连翘的主要成分之一连翘酯苷A(FSA)有抗炎活性,对弹性蛋白酶(PPE)有抑制作用.本文通过光谱法以及分子对接模拟法研究了 FSA与PPE的相互作用.结果表明,FSA对PPE之间存在π-阳离子、π-π共轭、氢键和疏水作用力等多种作用,能够形成稳定的1:1的复合物,使得FSA能够抑制PPE的活性,具有抗炎作用.     

Ab Initio Study of Conformational Properties of ( Z, Z)-, ( E, Z)-, and ( E, E)-Cyclonona-1,5-dienes

Ab initio calculations at the HF/6-31G^* level of theory for geometry optimization and MP2/6-31G^*//HF/6-31G^* for a single point total energy calculation are reported for the important energy-minimum conformations and transition-state geometries of (Z,Z)-, (E,Z)-, and (E,E)-cyclonona-1,5-dienes. The C₂ symmetric chair conformation of (Z,Z)-cyclonona-1,5-diene is calculated to be the most stable form; the calculated energy barrier for ring inversion of the chair conformation via the C_s symmetric boat-chair geometry is 58.3kJmol^–1. Interconversion between chair and twist-boat-chair (C₁) conformations takes place via the twist (C₁) as intermediate. The unsymmetrical twist conformation of (E,Z)-cyclonona-1,5-diene is the most stable form. Ring inversion of this conformation takes place via the unsymmetrical chair and boat-chair geometries. The calculated strain energy for this process is 63.5kJmol^–1. The interconversion between twist and the boat-chair conformations can take place by swiveling of the trans double bond with respect to the cis double bond and requires 115.6kJmol^–1. The most stable conformation of (E,E)-cyclonona-1,5-diene is the C₂ symmetric twist-boat conformation of the crossed family, which is 5.3kJmol^–1 more stable than the C_s symmetric chair–chair geometry of the parallel family. Interconversion of the crossed and parallel families can take place by swiveling of one of the double bonds and requires 142.0kJmol^–1.     

Ab Initio Study of Conformational Properties of ( Z, Z)-, ( E, Z)-, and ( E, E)-Cyclonona-1,5-dienes

Summary. Ab initio calculations at the HF/6-31G^* level of theory for geometry optimization and MP2/6-31G^*//HF/6-31G^* for a single point total energy calculation are reported for the important energy-minimum conformations and transition-state geometries of (Z,Z)-, (E,Z)-, and (E,E)-cyclonona-1,5-dienes. The C₂ symmetric chair conformation of (Z,Z)-cyclonona-1,5-diene is calculated to be the most stable form; the calculated energy barrier for ring inversion of the chair conformation via the C_s symmetric boat-chair geometry is 58.3kJmol^–1. Interconversion between chair and twist-boat-chair (C₁) conformations takes place via the twist (C₁) as intermediate. The unsymmetrical twist conformation of (E,Z)-cyclonona-1,5-diene is the most stable form. Ring inversion of this conformation takes place via the unsymmetrical chair and boat-chair geometries. The calculated strain energy for this process is 63.5kJmol^–1. The interconversion between twist and the boat-chair conformations can take place by swiveling of the trans double bond with respect to the cis double bond and requires 115.6kJmol^–1. The most stable conformation of (E,E)-cyclonona-1,5-diene is the C₂ symmetric twist-boat conformation of the crossed family, which is 5.3kJmol^–1 more stable than the C_s symmetric chair–chair geometry of the parallel family. Interconversion of the crossed and parallel families can take place by swiveling of one of the double bonds and requires 142.0kJmol^–1.     

铱(IV)离子与人血丙种球蛋白的作用研究

在0.1 mol•L^－1醋酸-醋酸钠(pH 5.0)体系中, 采用紫外吸收光谱、荧光光谱及同步荧光光谱法研究了人血丙种球蛋白(gamma seroglobulinum humanum, 简称GSH)与铱(IV)离子的相互作用. 结果表明, Ir(IV)离子使人血丙种球蛋白的构象发生了改变, α-螺旋含量减少, 并且用同步荧光光谱发现Ir(IV)离子与人血丙种球蛋白的作用位点更接近于色氨酸, 从而使色氨酸残基的疏水性略有减小. 荧光光谱结果表明Ir(IV)对人血丙种球蛋白内源荧光(342 nm)产生了较强的荧光猝灭作用, 根据不同温度下Ir(IV)对人血丙种球蛋白的荧光猝灭作用, 证明了这种荧光猝灭为静态猝灭机制, 计算了其结合常数和结合位点数, 从而得出了静电作用力为其主要的作用力.     

铱(IV)离子与人血丙种球蛋白的作用研究

在 0.1 mol?L-1醋酸-醋酸钠(pH 5.0)体系中, 采用紫外吸收光谱、荧光光谱及同步荧光光谱法研究了人血丙种球蛋白(gamma seroglobulinum humanum, 简称 GSH)与铱(IV)离子的相互作用. 结果表明, Ir(IV)离子使人血丙种球蛋白的构象发生了改变, α-螺旋含量减少, 并且用同步荧光光谱发现 Ir(IV)离子与人血丙种球蛋白的作用位点更接近于色氨酸,从而使色氨酸残基的疏水性略有减小. 荧光光谱结果表明Ir(IV)对人血丙种球蛋白内源荧光(342 nm)产生了较强的荧光猝灭作用, 根据不同温度下 Ir(IV)对人血丙种球蛋白的荧光猝灭作用, 证明了这种荧光猝灭为静态猝灭机制, 计算了其结合常数和结合位点数, 从而得出了静电作用力为其主要的作用力.     

Relation between the inverse Laplace transforms of I(tβ) and I(t): Application to the Mittag-Leffler and asymptotic inverse power law relaxation functions

The relation between H(k), inverse Laplace transform of a relaxation function I(t), and H_β(k), inverse Laplace transform of I(t^β), is obtained. It is shown that for β < 1 the function H_β(k) can be expressed in terms of H(k) and of the Lévy one-sided distribution L_β(k). The obtained results are applied to the Mittag-Leffler and asymptotic inverse power law relaxation functions. A simple integral representation for the Lévy one-sided density function L_1/4(k) is also obtained.AMS (MOS) classification: 33E12 Mittag-Leffler functions and generalizations, 44A10 Laplace transform, 60E07 Infinitely divisible distributions; stable distributions     

Tb(III)与PNIPAM接枝核壳纳米微球相互作用的研究

利用透射电镜、X射线光电子能谱、动态激光光散射和荧光光谱技术对Tb(III)与聚N-异丙基丙烯酰胺(PNIPAM)接枝核壳纳米微球PNIPAM-g-P(NIPAM-co-St) (PNNS)的相互作用进行了研究. 结果表明: Tb(III)和热敏性的核壳纳米微球PNNS有显著的相互作用. 其一, Tb(III)可与PNNS中酰胺基团上的氧原子配位形成微球配合物Tb(III)-PNNS; 其二, Tb(III)-PNNS微球配合物兼具热敏性; 其三, 该配合物在545 nm处的荧光强度较Tb(III)增大了233倍, Tb(III)与PNNS分子间能量传递达到50%, 当Tb(III) 质量分数为12%时荧光强度最大.     

密度泛函理论研究DMSO溶剂中邻-二(吡咯-2-甲酰胺基)亚苯与卤素阴离子间的超分子作用

采用混合密度泛函B3LYP方法, 在LANL2DZ水平上优化DMSO溶剂中邻-二(吡咯-2-甲酰胺基)亚苯(PFP)及其卤素阴离子复合物的几何构型, 从几何结构参数、电荷布居、前线轨道、结合能以及热力学参数等角度探讨复合物形成过程中主体分子的构象变化以及主客体间的超分子作用. 研究结果表明, 邻-二(吡咯-2-甲酰胺基)亚苯识别卤素阴离子是一个自发过程. 复合阴离子过程中, 两者的前线轨道发生作用, 电子容易从卤素阴离子的HOMO向主体分子的LUMO转移. 在所形成的四种复合物PFP:X^－(X^－＝F^－, Cl^－, Br^－, I^－)中, 以PFP:F^－最稳定, 与文献报道邻-二(吡咯-2-甲酰胺基)亚苯识别卤素阴离子能力的实验结果相一致. 设计合成含多个吡咯酰胺基团、并能形成合适“杯口”大小的主体化合物, 将增强对卤素阴离子的识别能力.     

1,2,4-三氮杂苯-(H2O)n复合物氢键相互作用的密度泛函理论研究

用密度泛函理论方法在B3LYP/6-31++G**水平上对1,2,4-三氮杂苯-(H₂O)_n (n＝1, 2, 3)氢键复合物的基态进行了结构优化和能量计算, 结果表明复合物之间存在较强的氢键作用, 所有稳定复合物结构中形成一个N…H—O氢键并终止于弱O…H—C氢键的氢键水链的构型最稳定. 同时, 用含时密度泛函理论方法(TD-DFT)在TD-B3LYP/6-31++G**水平上计算了1,2,4-三氮杂苯单体及其氢键复合物的单重态第一¹(n, π^*)垂直激发能.     

吡唑啉衍生物与溶剂相互作用的研究

通过对一类吡唑啉衍生物（1-苯基-3-（N，N-二甲基氨基苯乙烯）-5-（4-N，N-二甲基氨基苯基）-2-吡唑啉）在不同溶剂中的光谱行为，研究了该衍生物和溶剂分子间的一般相互作用和特殊相互作用．发现利用吡唑啉溶液的荧光猝灭现象能对其和溶剂分子间不同相互作用问题提供有价值的信息．     

同步荧光光谱法研究明胶蛋白质与铜(II)的相互作用

利用同步荧光光谱技术,研究了pH为10.0时,Cu2+离子与明胶的相互作用,推导出含有n个键合位置的明胶大分子与Cu2+离子的结合公式;用明胶中两种荧光基团的荧光强度变化数据,线性拟合出Cu2+离子与明胶的结合常数K和结合位点数n.讨论了Cu2+离子对明胶分子构象的影响.非线性拟合结果与实验值相当吻合.     

(R)-4-menthen-3-one in the synthesis of (3S)-methylundecand (2S)-methyldec-1-ylbromides, key synthons for (S,S,S)-diprionylacetate

New capabilities for the synthetic use of (R)-4-menthen-3-one were demonstrated using as examples (3S)-methylundec- and (2S)-methyldec-1-ylbromides, key synthons for (S,S,S)-diprionylacetate (sex pheromone of pine sawflies of genera Diprion and Neodiprion).     

锌试剂与壳聚糖的结合反应机理的研究

为从分子水平认识多糖分子与小分子之间相互作用的机理,应用光谱法研究了壳聚糖(CTS)与锌试剂(ZCN)的相互作用机理;测得ZCN-CTS复合物吸收光谱出现新的吸收峰所需的临界ZCN/CTS摩尔比为2.67×103, CTS对ZCN的最大结合数为6.93×103,实验值与理论值相吻合,证明了多糖与生物探针相互作用理论模型的可靠性;探讨了ZCN与CTS相互作用产生变色反应的机理,认为其是在ZCN与CTS大分子间发生静电相互作用的基础上,主要由ZCN与CTS大分子间的疏水相互作用所引起.     

The stereochemistry of the dichlorocobalt(III) complexes with (2S,5S,9S)- and (2S,5R,9S)-trimethyltriethylenetetraamines

Dichlorocobalt(III) complexes of (2S,5S,9S)-trimethyltriethylenetetraamine (L₁) and (2S,5R,9S)-trimethyltriethylenetetraamine (L₂) have been prepared. Both L₁ and L₂ coordinate to the cobalt(III) ion to give three isomers: Λ-cis-α, Δ-cis-β, trans isomers for L₁ and Δ-cis-α, Δ-cis-β, trans isomers for L₂. Each of the trans-dichloro complexes of the two ligands have been isomerized stereospecifically to the cis-α-dichloro complex in methanol, and each of the cis-α-dichloro complexes stereospecifically to the trans-diaqua complex in water. Both the geometrical and optical inversions took place at the same time in the observed stereospecific isomerizations.     

Investigation of the Interaction Between Sodium （meta） Arsenite and Catechin via ESI Tandem Mass Spectrometry

Catechin,one of the main components of green tea,is considered to have the remedy effect of arsenic poison,although the chemical mechanism is not well known.In this study,sodium(meta)selenite,which is used as herbicide and insecticide as well as rodenticide,was simply mixed with catechin in the CH3OH/H2O(volume ratio 50∶50)solution to investigate the interaction between toxic inorganic arsenic compound and catechin via ESI tandem mass spectrometry.The interaction products of mono-methylated arsenic with catechin in the presence of methanol were identified in the negative mode.Collission induced dissociation(CID)mass spectrometric measurements indicate that monomethylated arsenic was "alkylated" strongly by conjugation at the sites of C2' and C5' in the phenyl ring B of the catechin.The interaction mechanism between sodium(meta)arsenite and catechin was proposed.The results provide useful information to understand the chemical pathway of the detoxification of the arsenic toxicity by catechin.     

N-磷酰化肽酯及小肽与溶菌酶相互作用的ESI-MS研究

用ESI-MS研究了一系列结构具有可比性的N-磷酰化肽酯及小肽和溶菌酶的非共价相互作用, 比较了磷酰化肽酯及小肽分子中的不同基团对相互作用的影响. 结果表明—OH对其与溶菌酶的相互作用有较大贡献; 芳香环由于位阻原因, 对相互作用有促进和阻碍双重效应; 当—OH与芳香环相连时会发生协同效应, 可使相互作用显著增强. 磷酰化肽酯及小肽的体积大小、空间位阻对相互作用亦有显著影响. 磷酰化二肽中氨基酸残基的构型、顺序、碳链长短的变化(增加1～2个C)对其与蛋白溶菌酶之间的相互作用在质谱中没有表现出影响. 分子结构较为伸展、分子柔顺性好、空间位阻较小的磷酰化小肽更容易使蛋白在溶液中的构象趋于收缩, 而构象较为收缩的蛋白分子更易结合空间位阻较小的磷酰化小肽分子.     

双核Au(I)磷硫配合物激发态性质和金属间弱相互作用的从头算研究

采用MP2和CIS方法分别优化双核Au(I)磷硫配合物, [Au₂(SHCH₂SH)₂]^2＋ (1), [Au₂(SHCH₂SH)(PH₂CH₂PH₂)]^2＋(2), [Au₂(PH₂CH₂PH₂)₂]^2＋ (3), [Au₂(SHCH₂SH)(SCH₂S)] (4), [Au₂(PH₂CH₂PH₂)(SCH₂S)] (5)和[Au₂(SCH₂S)₂]^2－ (6), 基态和激发态的结构. 计算结果表明基态时1～6中存在Au(I)-Au(I)弱吸引作用, 激发态时1～5的金属间相互作用明显增强而6则减弱, 这与实验研究结果一致. 单激发组态相互作用计算揭示: 磷硫配体的更替使得Au(I)配合物跃迁性质呈现MC→MMLCT→MLCT的规律性变化(MC: 金属中心; MMLCT: 金属金属到配体电荷转移; MLCT: 金属到配体电荷转移).