Recognizing ortho-, meta- or para-positional isomers of S-methyl methoxylphenylmethylenehydrazine dithiocarboxylates by ESI-MS2: The positional effect of the methoxyl substituent

The dissociation chemistry of the ortho-, meta- or para-isomers of protonated S-methyl methoxyl- (or chloro-) benzenylmethylenehydrazine dithiocarboxylate, RPhCHN–NHC(S)–SCH₃ (R = MeO– or Cl–), has been investigated by collision induced dissociation experiments and DFT theoretical calculations. The three methoxyl-substituted isomers were easily differentiated according to the different abundance of the characteristic ion at m/z 136, resulting from the varying reactivity of the (NSC)SCH₃ elimination. This fragmentation is triggered by the positive charge upon protonation on the imine N2. Relative to the meta isomer, the positive charge on N2 in the para isomer is dispersed due to the electron donating resonance of the methoxyl group, which leads to higher energy barrier in the dissociation reaction and the less abundant product ion (m/z 136) in the MS/MS. (NSC)SCH₃ elimination of the ortho- isomer is further suppressed due to both the resonance effect and the “ortho effect” (an intramolecular hydrogen bond), with much higher energy barrier and extremely lower abundance of the fragment ion (m/z 136, 0.4%). The chloro substituted isomers, however, are short of the above positional effects due to the weak electronic effect of the substituent, and share the similar tandem mass spectrum.     

Banach空间中带Poisson跳的随机种群方程的数值分析

本文研究Banach空间中带Poisson跳的随机种群方程,通过离散使之成为随机微分方程,进而运用显式Euler公式来分析其数值解与解析解的误差.     

沪铜期货及其期权的量化定价实证研究

作为最大的铜消费市场,铜在我国占据着最重要地位。随着2018年9月沪铜期货期权正式登陆上海期货交易所,我国铜交易产品进一步与国际接轨。虽然拥有世界领先的铜交易市场,但我国学术领域尚缺乏采用量化方法对沪铜期货及其期权的深入实证研究。在大宗商品量化领域,Schwartz二因子模型^[1]被看作是量化期货定价的基准模型,本文通过实证分析发现经典二因子模型在中国市场应用时会产生“水土不服”,因此本文采用波动参数的思想,修正了Schwartz二因子模型在中国沪铜市场的“水土不服”。另外,根据早期文献对认购期货期权的量化定价模型^[2,3],本文明确了认沽期货期权的量化定价公式,并通过对沪铜期货期权定价模型的实证分析,发现目前沪铜期货期权存在套利空间。     

飞秒激光剥蚀-多接收电感耦合等离子质谱原位微区分析青铜中铅同位素组成-以古铜钱币为例

建立了飞秒激光剥蚀-多接收电感耦合等离子质谱(fLA-MC-ICPMS)铅同位素原位微区分析方法,分别利用溶液法(SN-MC-ICPMS)和激光剥蚀法(fLA-MC-ICPMS)对15个铜(黄铜,青铜)国家标准物质进行了实验分析,测试的结果表明CuPb12(GBW02137)中Pb同位素组成非常均一,可作为以铜为基体的青铜、黄铜及铜矿中Pb同位素原位微区分析的外部参考物质。对CuPb12进行了112次fLA-MC-ICPMS Pb同位素分析测试,其加权平均值与溶液法测定的Pb同位素比值在2σ误差范围内完全一致,208 Pb/204 Pb和207Pb/206Pb比值的内部精度RSE分别小于90和40ppm,外部精度RSD分别小于60和30ppm。利用本实验室建立的fLA-MC-ICPMS分析方法对13个古铜钱币中Pb同位素进行了原位微区无损伤分析,测试结果表明,不同朝代古钱币中Pb同位素组成差异较大,即使同一朝代的古钱币其Pb同位素组成也不尽相同。     

红外光学材料折射率温度系数测量装置

本文介绍一台红外光学材料折射率温度系数测量装置。该装置是由温控系统、精密测角系统、光学系统和电器控制系统等组成的一台高精度全自动化测量系统，采用改进的自准直法测量折射率温度系数值。该装置达到的主要技术指标：工作波长为2～12μm，温度范围为-50～150℃，测量不确定度为3%，可满足各种红外光学材料折射率温度系数测量的要求。利用该装置对红外材料锗折射率温度系数值进行了测量，并对测量数据进行了报道。     

Top介子与HERA和THERA对撞机上的单顶夸克产生

讨论计算了TC2模型预言的Top介子在HERA和构想中的THERA对撞机上对t道eq→et过程中的单顶夸克产生的贡献.结果表明:中性Top介子对ec→et过程中的单顶夸克产生有较大的贡献.在绝大部分参数空间内,过程的产生截面在1—6pb范围内,因此,在HERA和THERA对撞机上通过eq→et过程可探测中性Top介子的可能物理迹象     

Chemical Potential Dependence of Dressed-Quark Propagator

A method for obtaining the low chemical potential dependence of the dressed quark propagator from an effective quark-quark interaction model is developed. Of particular interest here is to give a generalrecipe to find without arbitrariness the solution representing the “Wigner“ phase at non-zero chemical potential for the purpose of studying QCD phase structure.     

多量级多向梯度海空复杂背景红外弱点目标检测

由于红外图像一般带有较大的噪声，采用传统的目标检测方法效果不理想。本文提出了一种新的海空背景下受强杂波和噪声污染的红外图像弱点目标检测算法。用多个量级梯度对图像目标进行检测，并对检测的结果进行了表决融合。结果表明，基于表决融合的多量级多向梯度检测消除了云层、海浪和海天线等背景干扰，在实现高检测概率的同时，不仅可以达到较低的虚警概率，而且可检测信杂比为1的点目标。     

聚乙二醇-钍试剂-硫酸钠体系中非有机溶剂萃取光度法测定铁

本文研究了铁（Ⅲ）－ＰＥＧ（聚乙二醇－２０００）－钍试剂－Ｎａ２ＳＯ４体系的析相光度法并应用于测定Ｆｅ（Ⅲ），最适酸度为４．６（ＮａＡｃ－ＨＡｃ）缓冲溶液，其络合物的最大吸收位于５６６ｎｍ，表观摩尔吸光系数为８．０６×１０３Ｌ·ｍｏｌ－１·ｃｍ－１。Ｆｅ（Ⅲ）浓度在０—３０μｇ·ｍＬ－１范围内服从比耳定律，该方法用于发样中铁的测定，获得了满意结果     

Calculation of equation of state of QCD at zero temperature and finite chemical potential

In this paper we calculate the equation of state (EOS) of QCD at zero temperature and finite chemical potential by using several models of quark propagators including the Dyson-Schwinger equations (DSEs) model, the hard-dense-loop (HDL) approximation and the quasi-particle model. The results are analyzed and compared with the known results in the literature.