在线近红外光谱预处理对废旧纺织品定性识别的影响

将近红外光谱分析技术与一阶导数、离散小波变换、标准正态变换、多元散射校正、 S-G平滑、移动平均平滑、均值中心化和最大最小归一化8种预处理方法相结合,采用其单一及组合的方法,对聚酯、锦纶、腈纶、棉、毛、真丝、聚酯/棉、聚酯/锦纶、聚酯/氨纶、聚酯/毛、真丝/棉、锦纶/氨纶和特殊类共计13类织物的3620个近红外谱图进行预处理,并建立基于深度卷积神经网络的废旧纺织品定性识别模型。依据定性模型的识别准确率,探讨出适宜该类数据集的谱图预处理方法。研究结果表明,采用S-G平滑、均值中心化+S-G平滑和标准正态变换+S-G平滑的方法预处理后,所得模型的识别准确率均在96%以上。将此3种模型与未经预处理的原模型分别导入“分拣装置”中,对未参与建模的280个样品进行成分识别检验,经预处理优化后的模型识别准确率均高于原模型的89.6%。且均值中心化+S-G平滑预处理后,模型的识别准确率最高达96.8%,识别、分拣时间小于2 s。因此,对原模型样本的近红外光谱数据进行预处理可极大提高模型的识别准确率,为废旧纺织品的在线高效识别与自动分拣提供新方法。     

废旧聚酯/棉混纺织物的在线近红外定量分析与自动分选

在前期探究的最佳测试条件下,利用自主研制的“纤维制品主体组分高效识别与分选装置”对废旧聚酯/棉混纺织物样品进行在线原始近红外光谱采集。基于在线原始谱图,探讨出最佳光谱预处理方法为S-G平滑+最大最小归一化(MMN)+S-G导数,并利用偏最小二乘法建立了废旧聚酯/棉混纺织物的在线近红外定量分析模型,模型的交互验证均方根误差(RMSECV)为1.47,校正相关系数(RC)、验证相关系数(RV)值均不小于0.99,校正相对预测偏差(RPDC)为18.17,验证相对预测偏差(RPDV)为13.13,交互验证相对预测偏差(RPDCV)为11.76。为验证模型的可靠性,选取30个外部样本进行在线验证,验证结果的线性方程为y=(1.00±0.01)x-(0.88±0.56),预测准确率为93.3%。将模型导入分选装置的“纺织品在线主控程序”后,对设备设定不同聚酯含量织物的分选类别,即可对废旧聚酯/棉混纺织物样本进行含量预测,并通过装置的吹分分选系统将样品自动吹扫到相应的收集框中。每个样品预测并分选的时间小于2 s,机械自动分选结果无误。利用所建模型和分选装置可对废旧聚酯/棉混纺织物进行在线高效测定与自动分选。     

单光子/光电子电离-膜进样质谱法在线检测水中醚类汽油添加剂

采用膜进样-光电子磁场增强电离(MEPEI)/单光子电离(SPI)复合电离源飞行时间质谱(TOF-MS)在线分析水中醚类汽油添加剂:甲基叔丁基醚(MTBE)、乙基叔丁基醚(ETBE)、甲基叔戊基醚(TAME)和二异丙基醚(DIPE)。膜进样方式无需样品前处理,通过渗透蒸发实现液体样品在线富集;SPI电离碎片离子少,谱图简单,可利用分子离子进行快速的半定性分析;MEPEI产生样品分子碎片可精确定性同分异构体,从而克服直接进样时复杂基质中重叠峰解析的难题。在最优实验条件下:膜温度为60℃,膜厚度为50μm,膜面积为160 mm2,单个样品分析时间小于100 s。MTBE,ETBE,TAME和DIPE的检出限分别达到5.5,4.8,3.3和4.3μg/L。本方法成功应用于模拟地下水中MTBE类汽油添加剂的快速检测。     

近红外光谱法最小二乘双胞胎支持向量机的应用研究

依据中药大黄的近红外光谱信息,采用最小二乘双胞胎支持向量机( LSTSVM)算法,通过MATLAB软件编程,建立参数可优化识别模型,实现了对中药大黄的真伪鉴别.将实验材料98个大黄样品随机划分为训练集和测试集,对于训练集60个样品采用留1/5法交叉验证优化模型参数,以所选最优化参数结合训练集样品的近红外光谱建立最优识别模型,对测试集的38个样品的真伪迸行识别,识别率可达97.4％.结果表明,LSTSVM算法是一种有效的识别方法,可依据中药大黄的近红外光谱对其真伪进行快速识别.同时,本研究将大黄样品6次随机划分为训练集和测试集,建模预测平均识别率为93.4％,表明采用LSTSVM算法建立识别模型具有较好的稳健性.     

纤维素纤维材料几种降解方法的研究

测试和比较了天然棉纤维织物和几种人造可再生纤维素纤维(竹原纤维、莫代尔纤维和天丝纤维)在实验室条件下和大环境堆肥条件下的生物降解性.生物降解行为的测试分别采用ASTM D5988-03、堆肥法和酶催化降解法,以比较几种织物在自然环境和微生物培养基条件下的降解速度;结合红外光谱通过分析降解前后结构的改变研究不同的降解方法对纤维素材料的降解程度.结果表明纤维素类纤维织物均表现出良好的生物降解性,并且人造可再生纤维素纤维的降解速度高于天然棉纤维.和传统的实验室条件下测量织物降解性的方法相比,堆肥中含有更多的微生物和酶活性组分,加速了纤维素材料的分解.     

裂解气相色谱法鉴别并测定涤纶纤维与天然纤维

应用裂解气相色谱法测定混纺织物中涤纶纤维与天然纤维的含量。将剪碎成小于2mm2小块的纤维样品(0.02g)与固体分散剂石英砂(4g)混合碾磨成均匀粉末后,称取一定量的样品混合物(其中涤纶纤维含量应小于0.21mg),置于色谱仪进样口上方的裂解器中,于550℃裂解。裂解物经Ultra ALLOY-5色谱柱(30m×0.25mm,0.25μm)分离。根据裂解色谱图所示,不同纤维的特征峰,对样品的纤维进行鉴定。涤纶纤维的线性范围在0.02~0.21mg之间。采用此法测定了织物样品中涤纶纤维的含量,所得测定值与溶解法测定值相符。用标准加入法做方法的回收试验,测得回收率为94.4%。     

多波长薄层扫描分析非那西丁和咖啡因

将阵列感光的光纤光谱仪与二维电移平台结合,完成多波长薄层反射扫描定量,提供二阶张量数据输出.设计的仪器采取“弓”形二维移动扫描,探头与薄层板间距2mm,能在200ms积分时间内同时获取紫外—近红外2048个波长响应值,利用Kubelka-Munk函数积分值定量,提高了薄层扫描定量的线性度和准确度,检出范围覆盖纳克到毫克...     

电渗泵-流动注射在线稀释法在火焰原子吸收光谱分析高浓度样品中的应用

采用电渗泵流动注射-火焰原子吸收法(FI-FAAS),研究了高浓度镁样品的在线稀释和分析.电渗泵在低流量时有很好的稳定性.利用控制采样时间的办法,可以准确采集微量样品,在线稀释.同时使用 T 型管对雾化量进行补偿,在线稀释倍数可达 10000 以上,相对标准偏差＜ 1.5% (n=6).通过改变采样电压(速度),载流速度和采样时间可以方便地得到不同的稀释倍数,测定速度可达 100个/h 样品以上.     

影响熔喷料聚丙烯熔体流动速率测试精密度的因素

采用熔体流动速率仪检测熔喷料聚丙烯材料的熔体流动速率,考察了三种不同熔喷料聚丙烯在不同测试条件下的熔体流动速率测试精密度的影响因素,结果标明当仪器恒温预热时间大于30 min、样品加入量8 g、料筒使用氮气吹扫8 s以上、精确控制仪器温度、装料时间控制在50~60 s以内、采用较小活塞位移距离并增加取样次数时,会大大提高测试结果的精密度。     

~1H核磁共振法测定三氯生的纯度

以丙烯酰胺为内标,氘代二甲基亚砜(DMSO-d6)为溶剂,对用1 H核磁共振法测定三氯生纯度条件进行试验。在脉冲延迟时间20s和扫描次数64等条件下得到1 H-NMR谱图。选择H-11(δ6.88)和δ5.59分别作为样品和内标的定量峰,取其积分峰面积平均值按公式计算三氯生的纯度。结果表明:样品与内标物的质量比在1.01~10.16内,与其定量峰面积比值呈线性关系。平行测定同一样品6份,按所得样品对内标物定量峰面积的比值,计算其相对标准偏差(n=6)为0.12%。按所提出方法分析了三氯生实样,结果的平均值(n=3)为99.78%,与质量平衡法所得结果(99.81%)相符。     

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.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.