Comparison of PARAFAC and PARALIND in modeling three‐way fluorescence data array with special linear dependences in three modes: a case study in 2‐naphthol

Owing to excited‐state proton transfer in 2‐naphthol solutions, the fluorescence excitation–emission matrices (EEMs) have factors that are highly dependent in three modes. For the first time such EEMs are used to compare the capability of PARALIND (PARAFAC with linear dependence) and conventional PARAFAC in modeling three‐way EEMs having linearly dependent factors in three modes. Two primary conclusions have been drawn. First, the results indicate that a 3‐factor PARAFAC model fit the data better than two PARALIND models (type 1 and 2) in this case while equally well with a specially PARALIND model (type 3); second, a negative core consistency (CC) in the 3‐factor PARAFAC model is reported but the type 3 PARALIND model reports a nearly 100 CC. This work has demonstrated that a properly constrained PARALIND can fit the very special EEMs of 2‐naphthol. The presence of negative CC associated with a perfect PARAFAC model would imply the presence of very special linear dependences in EEMs, which would be used as an “alarm” for the investigators to interpret the data more carefully when dealing with complicated environmental EEMs in the absence of a priori knowledge. Copyright © 2010 John Wiley & Sons, Ltd.     

β-DDB及其衍生物的结构与红外光谱特征

总结归属了肉豆寇醚酸甲酯、6－Br肉豆寇醚酸甲酯、β-DDB（6,6′－二甲氧基－4,5,4′,5′－二次甲二氧基－2,2′－二甲氧羰基联苯）及其5种衍生物的主要红外吸收谱带和特征,讨论了其红外吸收频率随化合物结构变化的规律。 结果表明分子中酯基的改变主要对羰基的伸缩振动频率有较大的影响,而对苯环的骨架振动影响较小;当苯环上H原子被其他取代基取代时,羟基及苯环的骨架吸收均发生显著变化。     

XPS研究聚苯胺的竞争掺杂行为

采用X射线光电子能谱（XPS）方法对不同反应体系下化学合成的聚苯胺（PANI）的结构和掺杂状况进行了研究。发现盐酸（HCl）掺杂的聚苯胺在样品后处理过程中易发生脱掺杂行为;在十二烷基苯磺酸钠（SDBS）和盐酸共存体系下合成聚苯胺时,对阴离子DBS-和Cl-发生竞争掺杂行为。结果表明DBS-与带正电荷聚苯胺链结合,起到了掺杂和诱导聚苯胺可溶性的作用,它的N1s和S2p谱图与单独采用十二烷基苯磺酸（DBSA）掺杂聚苯胺的谱图相似。但SDBS-HCl复合体系比单独采用DBSA体系更为有利。     

Implicit TVD schemes applied to gas-droplet detonation calculation

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多道全自动原子荧光光谱法测定土壤中的砷和汞

采用湿法消解对不同地区不同深度的土壤进行前处理,在最佳的实验条件下,应用原子荧光光谱法测定砷和汞的含量,测定的相对标准偏差As为1.4%~2.3%,Hg为2.0%~3.5%,加标回收率As为91%~106%,Hg为96%~102%。方法操作简单、快速,检出限、准确度均能满足土壤环境样品检验的要求。     

Universal Sub-Nanoreactor Strategy for Synthesis of Yolk-Shell MoS2 Supported Single Atom Electrocatalysts toward Robust Hydrogen Evolution Reaction

The coordination structure determines the electrocatalytic performances of single atom catalysts (SACs), while it remains a challenge to precisely regulate their spatial location and coordination environment. Herein, we report a universal sub-nanoreactor strategy for synthesis of yolk-shell MoS₂ supported single atom electrocatalysts with dual-anchored microenvironment of vacancy-enriched MoS₂ and intercalation carbon toward robust hydrogen-evolution reaction. Theoretical calculations reveal that the “E-Lock” and “E-Channel” are conducive to stabilize and activate metal single atoms. A group of SACs is subsequently produced with the assistance of sulfur vacancy and intercalation carbon in the yolk-shell sub-nanoreactor. The optimized C−Co−MoS₂ yields the lowest overpotential (η₁₀=17 mV) compared with previously reported MoS₂-based electrocatalysts to date, and also affords a 5–9 fold improvement in activity even comparing with those as-prepared single-anchored analogues. Theoretical results and in situ characterizations unveil its active center and durability. This work provides a universal pathway to design efficient catalysts for electro-refinery.     

Efficient Conversion of Biomass to Formic Acid Coupled with Low Energy Consumption Hydrogen Production from Water Electrolysis

The development of a new electrolytic water hydrogen production coupling system is the key to realize efficient and low-cost hydrogen production and promote its practical application. Herein, a green and efficient electrocatalytic biomass to formic acid (FA) coupled hydrogen production system has been developed. In such a system, carbohydrates such as glucose are oxidized to FA using polyoxometalates (POMs) as the redox anolyte, while H₂ is evolved continuously at the cathode. Among them, the yield of glucose to FA is as high as 62.5 %, and FA is the only liquid product. Furthermore, the system requires only 1.22 V to drive a current density of 50 mA cm⁻², and the Faraday efficiency of hydrogen production is close to 100 %. Its electrical consumption is only 2.9 kWh Nm⁻³ (H₂), which is only 69 % of that of traditional electrolytic water. This work opens up a promising direction for low-cost hydrogen production coupled with efficient biomass conversion.