直观推导式演进特征投影法对环境样本中多环芳烃的定性定量分析

基于新近发展的直观推导式演进特征投影法(HELP), 本文提出了一个对二维数据进行同时定性定量的分析方法, 并将其成功地用于环境样本中多环芳烃化合物定量解析。对于一维色谱难以定量的重叠峰, HELP方法充分利用色谱、光谱两方面的选择性信息, 得到了具有真实物理意义的唯一解。在定性分辨结果的基础上, 本文还提出了三种可能的定量方法。这种二维数据的解析新方法, 能大幅度地降低对色谱分离条件的要求, 可直接用于复杂实际样本的定性定量分析。     

多元曲线分辨等方法和红外光谱用于二硝基五亚甲基四胺的合成反应机理研究

通过红外光谱在线监测强酸催化下硝酰胺、甲醛和氨水合成二硝基五亚甲基四胺(DPT)的反应过程, 利用渐进因子分析(EFA)、直观推导式演进特征投影法(HELP)和多元曲线分辨-交替最小二乘法(MCR-ALS)等化学计量学方法对反应过程获得的红外光谱信息进行解析, 得到了各组分纯物质的浓度变化曲线和对应的红外光谱, 并把多元曲线分辨-交替最小二乘法与直观推导式演进特征投影法的分析结果进行比较, 得出可相互验证的一致结论, 以此推测出该反应合理的反应机理. 化学计量学方法对在线红外光谱信息的分辨可以快速有效地反映DPT合成过程中各组分的浓度和红外光谱变化情况, 对其反应机理研究具有重要指导意义.     

直观推导式演进特征投影法测定不同方法提取的国产血竭中龙血素B的含量

利用HPLC-DAD产生的二维数据和化学计量学方法-直观推导式演进特征投影法（HELP），解析了不同提取方法得到的国产血竭中的重叠色谱峰，并对其中的指标性成分-龙血素B进行了含量测定，结果满意。这表明这化学计量学方法与现代分析手段有机结合，将为中药等复杂体系的分析提供一条新途径。     

Zn(p-DMABA)~2Cl~2的低热固相合成及其X射线粉末衍射数据

报道了固配化合物Zn(p-DMABA)~2Cl~2(p-DMABA=N,N'-对二甲胺基苯甲醛)的低热固相合成，并用红外光谱、拉曼光谱、荧光光谱、差热热失重分析对产物进行了表征。结果表明p-DMABA是通过羰基氧原子与金属锌离子配位的。用粉末X射线衍射仪惧了衍射数据，并对衍射数据进行了指标化，指标化结果如下：Zn(p-DMABA)~2Cl~2为单斜晶系，空间群为P2~111(4)，晶胞参数：a=1.5897(2)nm,b=0.7560(4)nm,c=1.0373(1)nm,β=95.23(3)°,V=1.241(2)nm^3。     

气相色谱/质谱结合化学计量学解析方法用于植物精油成分分析

使用气相色谱/质谱(GC-MS)法对缬草精油和含有缬草精油的混配精油的化学成分进行了分析.采用直观推导式演进特征投影法(HELP)对二维数据中的色谱重叠峰进行了解析,得到两种精油的各个物质的纯色谱和纯质谱,同时利用交互移动窗口因子分析法(AMWFA)直接比较两种精油中的共有组分,提取出共有组分的纯质谱,通过与HELP法解析出的质谱进行比较,发现AMWFA法比HELP法能更快速鉴别出混配精油中的缬草精油.     

Formation of Pickering emulsion by use of PCM and SiC and application to preparation of hybrid microcapsules with interfacial polycondensation reaction

It was tried to form Pickering emulsion by use of paraffin wax as a phase change material (PCM) and SiC as solid powder and to apply to the preparation of the hybrid microcapsules with the interfacial polycondensation reaction. Pickering emulsion could be formed by stirring PCM and SiC in the continuous water phase. The mean diameter of PCM droplets in the (O/W) emulsion decreased with the added amount of SiC. The SiC weight adhered on the surface of PCM droplets become the maximum in the continuous phase with pH 6.8. The hybrid microcapsules with the shell made of SiC and polyurea resin film could be prepared by using Pickering emulsion. There was a critical adhesion weight of SiC, above which the hybrid microcapsules could not be formed. Thermal conductivity of hybrid microcapsules could be improved as compared with the PCM microcapsules. Copyright © 2015 John Wiley & Sons, Ltd.     

偏最小二乘近红外光谱模型中潜变量个数对模型传递性能的影响

以玉米中水分、蛋白质、脂肪和淀粉4种主要成分含量以及烟叶总植物碱的偏最小二乘近红外光谱(PLS-NIRs)模型传递为例,考察了模型中潜变量个数(nLVs)对模型传递误差的影响。研究发现,根据累积贡献率大于99.9%确定的玉米、烟叶样品PLS-NIRs模型的nLVs分别为1和13,nLVs=1时建立的玉米模型对两台从机样品4个成分的预测值和主机预测值的重现性指标均满足国标要求;nLVs=13时建立的烟叶总植物碱模型经分段直接校正(PDS)后,可使4台从机样品的平均相对预测误差(MRE)小于6%。采用留一交叉验证或四折交叉验证确定的玉米、烟叶PLS-NIRs模型的nLVs分别为5～10,16与19,在这些nLVs下建立的玉米PLS-NIRs模型对从机样品的预测误差显著增大,超过许可的误差范围,且模型即使经PDS校正后,从机样品预测值与主机样品预测值的重现性指标大多不满足国标要求;nLVs>13时所建烟叶总植物碱PLS-NIRs模型的转移误差随nLVs增大而增大,且PDS校正后不能保证模型对所有从机样品的MRE小于6%。根据累积贡献率大于99.9%或接近99.9%为准则选取nLVs,可...     

Triglycerides as Novel Phase-Change Materials: A Review and Assessment of Their Thermal Properties

Latent Heat Storage (LHS) with Phase-Change Materials (PCMs) represents a high energy density storage technology which could be applied in a variety of applications such as waste heat recovery and integration of renewable energy technologies in energy systems. To increase the sustainability of these storage solutions, PCMs have to be developed with particular regard to bio-origin and biodegradability. Triglycerides represent an interesting class of esters as the main constituents of animal and vegetable fats, with attractive thermal properties. In order to be used as PCMs, the thermal behaviour of triglycerides has to be fully understood, as in some cases they have been reported to show polymorphism and supercooling. This study assesses the suitability of triglycerides as PCMs by reviewing the literature published so far on their behaviour and properties. In particular, melting points, enthalpies of fusion, polymorphism, thermal conductivities, heat capacities and thermal cycling stabilities are considered, with a focus on LHS and thermal energy storage applications. In addition, the efforts conducted regarding modelling and the prediction of melting points and enthalpies based on chemical structures are summarized and assessed.     

Cuprous sulfide deposition method for visualization of latent fingermarks on unfired cartridge cases

A new chemical method for visualization of latent fingermarks on unfired cartridge cases is reported in this research. The method is based on two-step immersion of the cartridge cases in aqueous solutions of sulfuric acid and acidified sodium thiosulfate at room temperature. The chemical reactions that are occurring on the cartridge case's surface are leading to deposition of material in the furrows between the papillary line ridges thus visualizing the latent fingermark. The qualitative chemical composition of the as-deposited material was studied using X-ray powder diffraction analysis thus revealing that it corresponds to a low-crystalline hexagonal chalcocite phase cuprous sulfide (Cu₂S). The performance of the method was studied on fresh and aged fingermarks, and according to the results, it can visualize latent fingermarks that are up to 9 months old. The newly proposed method provides good performance considering the most important qualitative and quantitative parameters that describe each fingermark, that is, satisfactory contrast between the papillary line ridges and the background furrows, possibility of recognizing the pattern of each fingermark (arch, loop, and whorl), clarity and continuity of the friction ridges, and clarity of the second level characteristics and features. The proposed method is simple, fast, inexpensive, and reliable.     

Thermal Energy Storage and Heat Transfer of Nano-Enhanced Phase Change Material (NePCM) in a Shell and Tube Thermal Energy Storage (TES) Unit with a Partial Layer of Eccentric Copper Foam

Thermal energy storage units conventionally have the drawback of slow charging response. Thus, heat transfer enhancement techniques are required to reduce charging time. Using nanoadditives is a promising approach to enhance the heat transfer and energy storage response time of materials that store heat by undergoing a reversible phase change, so-called phase change materials. In the present study, a combination of such materials enhanced with the addition of nanometer-scale graphene oxide particles (called nano-enhanced phase change materials) and a layer of a copper foam is proposed to improve the thermal performance of a shell-and-tube latent heat thermal energy storage (LHTES) unit filled with capric acid. Both graphene oxide and copper nanoparticles were tested as the nanometer-scale additives. A geometrically nonuniform layer of copper foam was placed over the hot tube inside the unit. The metal foam layer can improve heat transfer with an increase of the composite thermal conductivity. However, it suppressed the natural convection flows and could reduce heat transfer in the molten regions. Thus, a metal foam layer with a nonuniform shape can maximize thermal conductivity in conduction-dominant regions and minimize its adverse impacts on natural convection flows. The heat transfer was modeled using partial differential equations for conservations of momentum and heat. The finite element method was used to solve the partial differential equations. A backward differential formula was used to control the accuracy and convergence of the solution automatically. Mesh adaptation was applied to increase the mesh resolution at the interface between phases and improve the quality and stability of the solution. The impact of the eccentricity and porosity of the metal foam layer and the volume fraction of nanoparticles on the energy storage and the thermal performance of the LHTES unit was addressed. The layer of the metal foam notably improves the response time of the LHTES unit, and a 10% eccentricity of the porous layer toward the bottom improved the response time of the LHTES unit by 50%. The presence of nanoadditives could reduce the response time (melting time) of the LHTES unit by 12%, and copper nanoparticles were slightly better than graphene oxide particles in terms of heat transfer enhancement. The design parameters of the eccentricity, porosity, and volume fraction of nanoparticles had minimal impact on the thermal energy storage capacity of the LHTES unit, while their impact on the melting time (response time) was significant. Thus, a combination of the enhancement method could practically reduce the thermal charging time of an LHTES unit without a significant increase in its size.