指纹遗留时间判定的研究进展

指纹遗留时间对公安机关确定案发时间及嫌疑人具有重要作用。然而作为指纹研究的重点和难点,指纹遗留时间的研究相对较少。本文主要综述了就指纹的形态特征、光效应、电效应和指纹的物质成分等来判断指纹的遗留时间,同时指出这些方法的优点及局限性。最后,就指纹遗留时间的研究提出了几点展望。     

潜指纹残留物中油脂的气相色谱分析

建立一种适于分析潜指纹残留物中油脂组成的简便快速、灵敏可靠的GC/FID分析方法。以V(正己烷)∶V(CH2Cl2)=1∶10为提取剂,HP-5毛细管色谱柱和氢火焰离子检测器进行分析。潜指纹残留物中油脂组成复杂,不同个体捺印所得样品组成之间既有共同之处,又有各自典型特征;暗处保存及自然光照条件下,油脂组成发生变化,油脂含量总体呈下降趋势,但部分物质含量呈波动性变化;两种老化方式下的变化趋势相似,但自然光照条件下油脂衰减速度较快,光照10天后的潜指纹残留物中仍可见含量丰富的油脂。方法灵敏度能够达到单枚指纹残留物检测要求。     

指纹物质中毒品检测的研究进展

指纹作为案件现场中最常见的物证之一,不仅包含了可用于人身识别的形态特征,还蕴含了丰富的反映遗留人人身特点的化学信息。通过对指纹中毒品物质的检测及分析,可提供指纹遗留者毒品的吸食、接触情况,将其与特定案件相联系,反映个人生活方式信息,为涉毒人员的发现提供新思路。该文利用文献计量学方法总结了该领域的发展脉络以及研究现状与热点,主要总结了目前已建立的指纹物质中毒品分析检测的各种技术方法和特点,并对未来研究方向及难点进行评述,以期为实际案件指纹中的毒品检测提供参考。     

绿茶的色谱指纹谱分类模式初探

以绿茶的数字化色谱指纹谱为基础,探讨用指纹谱来分类绿茶的新模式。各批次绿茶样品间的两两重叠率可作为筛选构建特征指纹谱样品的依据,14个绿茶样品按照特征指纹检出率和总差异率的不同初步划分为3个级别。本法从内在组成上为绿茶的分类提供了一个客观量化的界定标准,有别于过去凭借外形口感的经验评估,可为茶叶乃至自然界其它植物的化学分类提供新的视角。     

N,O-二酰化羟基苯胺衍生物的红外光谱特征

研究了Ｎ,Ｏ － 二酰化羟基苯胺衍生物分子中的两个酰羰基及相关化学键的特征红外光谱, 讨论了这些红外光谱特征随化学结构变化的关系。     

大气开放光路傅里叶变换红外光谱的定性分析

通过目标波段熵最小化(BTEM)和目标因子分析(TFA)两种化学计量学方法研究了大气开放光路傅里叶变换红外(OP/FT-IR)光谱,从多组分测量数据重建特定目标分子的光谱特征,以实现对大气这种复杂体系的定性分析。在牧场周围完成了5次连续OP/FT-IR光谱测量,将光谱按照测量时间顺序排列,获得5个数据矩阵作为研究对象。结果表明,BTEM和TFA两种方法均可从多组分光谱数据矩阵重建出目标分子的光谱特征,重建效果略有差异。TFA能够克服干扰,提取出目标分子的光谱特征,其重建光谱与相应的参考光谱高度相似。BTEM方法无需目标分子的参考光谱,目标函数最优解所对应的谱图就是纯组分光谱。本研究利用两种方法各自的优势,用化学计量学方法定性分析OP/FT-IR光谱,不仅将BTEM方法应用于OP/FT-IR光谱,而且比较这两种方法的应用,为实现多组分OP/FT-IR光谱定性分析提供了新思路。     

人工蚕蛹虫草和冬虫夏草水溶性成分的相对归属分析

为对相近中药的化学指纹图谱进行比较研究,充分利用联用色谱所得的光谱、色谱信息与光谱相关色谱方法,分析了蚕蛹虫草和冬虫夏草的水溶性成分的异同,实现了蚕蛹虫草和冬虫夏草水溶性成分化学指纹图谱中相应化学组分的归属分析。其中,蚕蛹虫草和冬虫夏草有5个共有组分,分别有4个和6个相异组分。实验表明：该方法可对复杂中药成分及其指纹图谱进行快速比较分析。     

利用样本成分耗散物的非线性化学指纹图谱原理及相似度计算与评价

在恒温恒压条件下,以丙酮和样本中底物作为主要耗散物的不同成分的样本对非线性化学反应机理产生不同影响,从而引起反应体系电位-时间曲线形状不同变化为特征的B-Z化学振荡体系为例,就非线性化学指纹图谱原理进行了详细研究和讨论,并提出了计算非线性化学指纹图谱系统相似度的通用方法.利用系统相似度和欧氏距离、相关系数及夹角余弦对不同生产批次古汉养生精和18种其他样本的非线性化学指纹图谱的相似度进行了计算与分析.结果表明,相关系数和夹角余弦都不能用来作为评价非线性化指纹图谱相似度的指标.利用欧氏距离公式计算指纹图谱的非参数型相似度时,能正确反映指纹图谱的特征差异,但用其计算参数型相似度时,则有时不能正确反映样本非线性化学指纹图谱特征差异的相对程度.系统相似度能最真实反映样本指纹图谱之间差异程度,是4种相似度计算方法中最好的,可用于非线性化学指纹图谱相似度计算与评价.成功提出了一种经济、简便、易行和有效的鉴别样本真伪与评价其质量的科学方法.     

基于指纹物质分析的人群特征刻画研究进展

指纹作为犯罪现场最常见、且运用历史最久的重要物证,因其人各不同,终身基本不变的特性广泛运用于人身判定。但除了形态学特征外,指纹物质中所包含的化学信息对于遗留者特征的刻画和个体行为的追踪溯源也具有重要价值,不仅能为侦查人员提供分析线索,还能一定程度上解决因现场指纹模糊或部分缺失导致的证据价值丢失问题。本文从指纹中的内源性物质和外源性物质分析两大角度,对基于不同指纹物质进行人群特征的分析研究进行了探讨,总结了多种指纹物质的化学分析方法,并对其优势进行评述,以期为未来指纹物质相关的研究提供新的思路。     

多组分光谱相关色谱及其在中药色谱指纺图谱分析中的应用

基于正交投影理论和相关色谱方法提出多组分光色谱方法提出多组分光谱相关 色谱。为克服联用色谱仪器的不等性噪声影响，采用目标组分投影前后的光谱夹角 余弦判据，判断不同的中药色谱指纹图谱的相关组分色谱峰簇。该方法为中药指纹 图谱的数据处理、合理评价以及中药谱效学的基本理论研究提供一种实用的工具。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.