基于独立分量和神经网络的近红外多组分分析方法

采用小波变换对光谱数据进行压缩,用独立分量分析(ICA)方法提取近红外光谱数据矩阵的独立成分和相应的混合矩阵,再用BP神经网络对混合矩阵和实测浓度矩阵进行建模,提出了基于独立分量分析-神经网络回归(ICA-NNR)的近红外分析建模方法。进一步研究了独立分量数和网络中间隐层的神经元数对模型性能的影响,经优化后的ICA-NNR模型在相关系数与均方根误差两个指标上均优于直接用光谱矩阵作为输入所建立的模型。本方法用于玉米中水分、淀粉、蛋白质3种主要成分含量的同时测定,检验样品集的化学检测值与近红外预测值的相关系数分别达到:淀粉r=0.971,蛋白质r=0.976,水分r=0.975。     

植物纤维材料中化学成分含量模型的建立和含量测定方法

一种植物纤维材料中化学成分含量模型的建立方法，该方法包括采集植物纤维材料样品的近红外光谱，并采用化学计量学方法根据该近红外光谱建立植物纤维材料样品中化学成分含量的定量分析模型，其中，所述植物纤维材料样品至少部分为混合植物纤维材料样品，该混合植物纤维材料样品为所述至少一种化学成分含量已知的植物纤维材料样品的混合物。采用本发明提供的模型建立方法，只需要采集少量的化学成分含量分布不同的几个植物纤维粉末样品，即可获得建模所需的较多的化学含量不同的其它样品，从而大大减少样品的实地采集量，提高建模速度。通过控制化学含量的均匀分布还能够有效地提高模型的准确度。     

激光共焦显微拉曼光谱技术对手印中海洛因及其稀释剂的检测研究

利用激光共焦显微拉曼光谱技术对汗潜手印和油潜手印中的海洛因、烟酰胺、碳酸钠、葡萄糖、淀粉、蔗糖、滑石粉进行了检测,并对主要拉曼特征峰所对应的分子振动基团进行了识别,在此基础上,对手印中的混合毒品进行分析检测。实验结果表明,在不破坏手印的情况下,激光共焦显微拉曼光谱技术实现了对手印中海洛因、烟酰胺、碳酸钠、葡萄糖、淀粉、蔗糖、滑石粉的快速检测,对手印中混合毒品样品中的海洛因成分能够有效的识别,手印中的油脂不影响以上各物质的检测识别,通过显微红外光谱技术对试验结果的准确性进行了确认,研究结果将为相关涉毒案件的侦破提供有力的技术支持。     

近红外光谱法快速测定鲜木薯中淀粉含量

提出了用于现场快速测定鲜木薯中淀粉含量的近红外光谱法。取不同品种的鲜木薯样品90个,按国家标准方法(化学分析法)测得其淀粉含量。用近红外光谱法对此90个样品所制作的柱状样块的横截面进行光谱扫描,得其光谱图谱,并转换得到其一阶导数图。用CAUNIFT软件QPLS分析模块建立数学模型。结果表明:验证样品中淀粉的化学法测定值与近红外模型的预测值之间呈线性关系。用5份未知样品对所建模型进行外部验证,预测值与化学法测定值之间的绝对误差在2%以内,相对误差均小于5%。     

近红外光谱预处理中物理信号消除的理论假设和验证

提出了新的图谱预处理方法,消除近红外光谱中的物理信号,应用于样品的化学组分、结构分析、近红外建模等。将光谱信号分解为物理吸收和化学吸收两大类,提出理论假设,样品光谱中存在一段平滑的物理特征曲线,并可以进行消除。试验中选择注射用头孢哌酮钠粉针剂进行分析验证,共选择4个厂家5个批次的样品,每批次样品扫描10张光谱,通过计算标准偏差,和常规的基线校正预处理方法进行比较,然后通过加速试验,对比分析近红外光谱与有关物质含量的相关性,验证预处理方法的合理性。扣减样品光谱中物理特征曲线,得到重复性更好的图谱,标准偏差明显小于基线校正的结果,有关物质含量与近红外光谱正相关。     

拉曼光谱子空间重合识别修正液中氯代烃

利用拉曼光谱子空间重合对修正液中氯代烃成分进行识别分析。通过计算混合卤代烃组分与标准样品数据库拉曼光谱之间的子间空夹角,依据夹角变化排列筛选出含有最少标准样品数目的子空间,该子空间所含的标准样品组成为待定性混合氯代烃组成,从而实现对混合氯代烃组分的定性分析。将该方法用于修正液中氯代烃的成分定性分析,准确率达100%。该方法操作简单,检测时间短,准确率高,适用于多组分混合体系中的物质定性分析。     

漫反射傅里叶变换红外光谱法测定制剂中左氧氟沙星

采用新型的制样方法,利用漫反射傅里叶变换红外光谱(DRIFTS)法测定了左氧氟沙星制剂中左氧氟沙星的含量。选择1620 cm-1处的酮羰基伸缩振动吸收峰作为定量分析峰,以1580~1655 cm-1范围内的峰面积评估吸光度,吸光度与左氧氟沙星质量分数在0.20%~1.20%范围内呈良好的线性关系,相关系数为0.984,相对标准偏差(RSD)≤5.6%。新型制样方法可使样品与KBr基质混合更均匀,有效消除镜面反射光及排除辅料中不可溶淀粉对分析测定的干扰,提高分析结果的精密度和准确度;以含可溶性淀粉的左氧氟沙星标准样品绘制标准工作曲线可以消除少量可溶性淀粉对分析测定的干扰。DRIFTS法测定了3种市售制剂中左氧氟沙星含量,结果与紫外分光光度(UV)法基本一致。     

CCD近红外光谱快速测定柴油中的芳烃含量

研究了采用电感耦合器件（ＣＣＤ）近工外光谱仪在短波近红外区域（７００－１１００ｎｍ）、利用偏最小二乘回归（ＰＬＳ）测定柴油中芳烃含量的方法。考虑样品颜色对短波近红外光谱的影响,对波长范围的选择和基线处理方式进行了研究。考察了样品进入光路的时间对测定结果的影响。将ＣＣＤＮＩＲ对未知样品的预测结果与傅里叶变换近红外光谱（ＦＴ－ＮＩＲ）在长波近红外范围（１０００－２０００ｎｍ）的预测结果及液相色谱的测定     

同步辐射X荧光微探针扫描分析氟碳铈矿物中的稀土元素

北京正负电子对撞机国家实验室的增频光源提供的同步辐射白光，激发ＬＲＥＥＫ－系列，用ＳＲＸＲＦＭ扫描分析氟碳铈矿物中的轻稀土元素的分布。取同一矿区的氟碳铈矿物，粉碎至粒度〈３００目。一部分熔融，沉淀分离，转成稀土氧化物后，用ＸＲＦ法分析稀土分量。另一部分，不加任何粘结物质压在成Φ２６ｎｍ圆片作为ＳＲＸＲＦＭ扫描分析的参比样品，从而可计算样品中稀土的含量。     

基于子空间重合判断的混合醇组分光谱识别方法

针对光谱分析中传统的特征峰比对法对物质定性检测存在的不足,采用基于子空间重合判断的混合光谱模式识别方法对9种混合醇组分进行定性检测。此法将测量到的待定性混合醇光谱信息视为向量,通过计算混合醇组分拉曼光谱与标准样品数据库拉曼光谱的子空间夹角,并依据子空间夹角变化,排列筛选出含有最少标准样品数目的子空间,该子空间所包含的标准样品组成即为待定性混合醇组分组成,从而成功实现了9种混合醇组分的定性识别,识别率100%。该法具有测试时间短、测试结果准确、与被测物含量无关、操作简便等优点,适用于多组分混合体系的定性识别。     

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%.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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.