Using Neural Networks or Linear Models to Predict the Characteristics of Microcapsules Containing Phase Change Materials

Summary: Microcapsules with large amount of PRS® paraffin wax encapsulated and narrow size distribution were prepared by shirasu porous glass (SPG) emulsification technique and a subsequent suspension like polymerization process and then examined by DSC, laser diffraction and SEM analyses. An experimental design approach, based on a central composite design, was used to determine quantitatively the effect of PRS® paraffin wax/styrene mass ratio (PRS/St), percentage of polyvinylpyrrolidone/styrene mass ratio (%PVP/St) and water/styrene mass ratio (H₂O/St) on the microparticles properties. The results were fitted using two black-box models. The empirical equations allow the prediction of the amount of the paraffin wax encapsulated and the mean particle size in number as a function of aforementioned synthesis variables. It was observed that both models allowed to drawn the same conclusions. %PVP/St mass ratio was the most important parameter affecting the particle size distribution decreasing the average particle size with the increase of %PVP/St. On the other hand, PRS/St mass ratio has a direct influence on the latent heat of fusion.     

Tripod molecules build molecular networks and open-dimer capsules by weak interactions

Three tripod molecules, tris(2-methoxy-5-nitrobenzyl)phosphine oxide (1), tris(2-butoxy-3-methyl-5-nitrobenzyl)phosphine oxide (2), and tris(3-nitrobenzyl)amine (TNBA), were synthesized and crystallized. The structures of 1, 2, and their comparison (TNBA) were determined by X-ray crystallography. It is noteworthy that compound 1 interacted with adjacent molecules via π-π stacking and C-H···π interactions to yield an open supramolecular network with the porosity P in 8.9%, whereas compound 2 gathered closely...     

CuO Crystalline Modified Glassy Carbon Electrodes for Anodic Amperometric Determination of Hydrogen Peroxide

As an alternative selection of electrocatalytic surface modifier, the electrochemically generated copper oxides is re‐ investigated by using cyclic voltammetry (CV), scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). Interesting phenomena have been found, which indicate that the electrodeposition from the Cu²⁺ solution under cyclic voltammetric conditions can generate a transparent Cu(OH)₂ crystalline on the surface of glassy carbon electrodes, and this crystalline can be further transferred to a novel cubic opaque CuO crystalline of about 300 nm in size by second step of cyclic voltammetry in pH 12 NaOH solution. The final electrode (denoted as nano‐CuO/GCE) can catalyze the oxidation (as well as the reduction) of H₂O₂ in basic solutions. It shows pH dependent three‐part catalytic mechanism in the range from pH 7 to pH 14. In 0.10 mol/L NaOH solution, the amperometric response at 0.15 V (vs. SCE) can give a current sensitivity as high as 139 mA/(mol·L^?1) in the rage of 5.0×10^?7?6.0×10^?4 mol/L with a lower detection limit (s/n=3) of 2.5×10^?8 mol/L, and a current sensitivity of 78.4 mA/(mol·L^?1) in the rage of 6.0×10^?4–2.0×10^?3 mol/L. This electrode also has excellent reproducibility and stability. The mechanisms for the two steps of preparation and the catalytic reactions are proposed. The nano‐CuO crystalline modified electrode may have more applications in the field of electrochemical sensing.     

表面等离子体子共振传感器用于研究不同材质包裹的磁性纳米粒子性质

利用自行设计组装的以白色发光二极管为光源的表面等离子体子共振传感器实验装置, 检测了不同材质包裹的磁性纳米粒子连接靶向DNA与生物素化DNA探针的结合程度. 结果表明, 与聚苯乙烯磁性微球连接的靶向DNA相比, Fe3O4@SiO2核壳式纳米微球连接的靶向DNA与生物素化的DNA探针结合速率较快, 且其相对标准偏差较小.     

对羟基苯甲酸酯分子印迹电化学传感器的研制

利用分子印迹技术,以对羟基苯甲酸乙酯为模板分子,甲基丙烯酸为单体,在玻碳电极表面原位聚合分子印迹聚合物敏感膜.采用方波伏安法对对羟基苯甲酸乙酯在该印迹电极上的电化学行为进行了研究,当响应时间为15 min时,0.95 V(vs SCE)处的峰电流与对羟基苯甲酸乙酯的浓度在2.0×10-6 ～2.0×10-4 mol/L范围内呈线性关系,检出限(S/N=3)为1.0 μmol/L,而相同条件下,对羟基苯甲酸乙酯在控制电极上的响应非常小并对浓度变化不灵敏;同时在印迹电极上氧化峰电位较在裸电极上发生了微弱正移.同一支印迹电极对对羟基苯甲酸乙酯响应值的RSD为4.3%(n=10).该印迹电极对尼泊金酯类具有良好的选择性,对对羟基苯甲酸甲酯、丙酯以及丁酯的选择性系数分别为1.89、1.70和2.01;对结构相似的苯酚、对羟基苯甲酸、对氨基苯甲酸等响应不灵敏,对结构差异较大的如维生素C等几乎无响应.用该分子印迹电极对实际样品进行分析,加标回收率大于90%.     

三乙醇胺对聚邻苯二胺pH敏感电极性能的影响

在含有邻苯二胺和三乙醇胺(TEA)的酸性溶液中,用循环伏安法(CV)在铂电极上制备聚邻苯二胺(PoPD)薄膜.通过对该薄膜进行深入的电化学分析,并将结果与无三乙醇胺参与的聚邻苯二胺的性能进行比较,发现在三乙醇胺参与下得到的聚邻苯二胺薄膜在铂电极表现出更好的粘附性,同时在氢离子选择性电极方面表现出优良的性能.在pH 2～13范围内具有良好的Nernst响应,直线斜率为59.62 mV/pH,相关系数达0.99以上,碱性条件下响应时间可缩短至30 s左右.该电极对大多数普通干扰物具有较好的选择性,可用于实际样品的测试.     

聚苯乙烯负载多吡啶铂(Ⅱ)配合物选择性检测Mg2+离子

本文通过超声反应,将氮杂15-冠-5-苯乙炔引入聚苯乙烯负载多吡啶铂(Ⅱ)配合物.研究发现聚苯乙烯负载氮杂15-冠-5-苯乙炔基多吡啶铂(Ⅱ)配合物完全保持了单体多吡啶铂(Ⅱ)配合物的性质,并能够通过发光光谱的显著增强选择性地检测Mg²⁺离子.通过加入极性溶剂沉淀析出聚苯乙烯负载多吡啶铂(Ⅱ)配合物,从而达到分离的目的.     

Two 3-D Supramolecular Networks Containing Dimeric {Cu2X2} Cluster Units

Abstract  Two new 3-D supramolecular compouds: [Cu₂X₂(Hpyba)₂]_n (X = Br (1), I (2), Hpyba = 4-pyridin-4-yl-benzoic acid) have been hydrothermally synthesized and structurally characterized. Although both compounds exhibit different space groups, they have a similar structure. Each {Cu₂X₂} cluster unit interconnects to form a 1D stair-step chain. The Saturated Hpyba ligands are regularly appended to both sides of main chain, linked via N atoms of ligands. These infinite chains are further linked by H-bonds and π–π interactions to form a 3-D supramolecular network structure. The thermal stability of 1 and 2 was investigated by thermogravimetric measurements. Graphical Abstract  Two new 3-D supramolecular compouds [Cu₂X₂(Hpyba)₂]_n (X = Br(1), I(2), Hpyba = 4-pyridin-4-yl-benzoic acid) have been obtained under hydrothermal conditions. Both compounds exhibit a 1D stair-step chain structure based on the {Cu₂X₂} cluster units. These infinite chains are further linked by H-bonds and π–π interactions into forming a 3-D supramolecular network with two types of channels along different directions.      

HUMANN-based system to identify benzimidazole fungicides using multi-synchronous fluorescence spectra: An ensemble approach

In this paper, we approach, using neural computation and ensemble systems, a pattern classification problem in fluorescence spectrometry, the resolution of difficult multi-fungicide mixtures (overlapping), specifically the benzimidazole fungicides, benomyl, carbendazim, thiabendazole and fuberidazole. These fungicides are compounds of an important environmental interest. Because of this, from an analytical point of view, it is interesting to develop sensitive, selective and simple methods for their determination. Fluorescence spectrometry has proven to be a sensitive and selective technique for determination of many compounds of environmental interest, but in some cases it is not enough. HUMANN is a hierarchical, unsupervised, modular, adaptive neural net with high biological plausibility, which has shown to be suitable for identification of these fungicides and organochlorinated compounds of environmental interest. We propose two modular artificial intelligent systems, with a structure of pre-processing and processing stage, a multi-input HUMANN-based system, using multi-fluorescence spectra as input to the system, and a HUMANN-ensemble system. We analyze the optimal configuration of inputs and the ensemble in order to obtain better results. We study such figures as precision and sensitivity of the method. Our proposal is a smart, flexible and effective complementary method, which allows reducing the analytical and/or computational complexity of the analysis. Figure Stages in identification of benzimidazole fungicides Based on a contribution presented at the XIII International Symposium on Luminescence Spectrometry held in Bologna, Italy from Sept. 7–11, 2008.