α-环糊精修饰有机聚合物整体材料选择性富集室温磷光法测定土壤中的萘

合成了α-环糊精（α-CD）修饰的有机聚合整体材料,对合成的材料进行了表征,研究比较了α-CD修饰整体材料作为室温磷光固体基质的效果以及14种有机化合物在其上的室温磷光分析(RTP)行为。 α-CD修饰的有机聚合整体材料背景干扰低, 对二环芳烃类物质有较好的选择性和富集能力。 在α-CD修饰膜上,萘和7,8苯并喹啉的分配常数分别为5.03×103和2.94×102,表明修饰材料对萘有较好的选择性。 萘酚也能与修饰材料形成包络物。 但是由于较强的极性和在水中的溶解性,不能被有效富集。 对5.0×10-11 mol/mL萘,最大富集体积为300 mL。 采用SPE-RTP,萘和7,8苯并喹啉的检出限分别为9.80×10-12和4.60×10-11 mol/mL,RSD小于3.7%;线性范围分别为5.00×10-11~8.00×10-9 mol/mL和6.00×10-11~5.00×10-10 mol/mL。 应用修饰的膜片对土样中的萘进行选择性富集和测定,结果由GC-MS进一步确认。 用环己烷一步提取和SPE-RTP测定,萘可以被选择性富集。 在土壤样品中加萘标准0.012 8 mg,测得回收率（104.9±6.5）%。 土样中萘的浓度为（5.61±0.12） mg/kg,与GC-MS的较为吻合。     

Analysis of nickel-niobium alloys by inductively coupled plasma optical emission spectrometry

Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to the analysis of major and minor elements of Ni-Nb alloys obtained by aluminothermic reduction process. Digestion of samples was made using a mixture of HF+HNO₃. Minor and trace elements were determined without matrix separation. The precision for all constituents was <3%. Recoveries for the analyte-spiked samples were 95%.     

Interactions of water and methanol with a mixture of copper and zinc metals: a theoretical <Emphasis Type="Italic">ab initio</Emphasis> study

Ab initio cluster quantum chemical calculations at the Hartree–Fock and second-order Møller–Plesset perturbation theory levels were carried out to mimic the interactions of water and methanol with a mixture of Cu and Zn metals. It was shown that both molecular and dissociative adsorption of methanol on a mixture of Cu and Zn metal catalyst are preferred over the corresponding adsorptions of water. Estimated transition-state structures for dissociation of methanol into CH·₃ and OH· lie about 9.0 and 22.0 kcal/mol higher compared to the dissociated (forward reaction) and molecular adsorption (reverse reaction) complexes, respectively. Based on distinct radicals' bond energies with the active sites of the catalyst considered, it is suggested that hydrogen molecules could be formed through a chain of homogeneous reactions of methyl radicals released into the gas phase with the water and/or methanol molecules.     

Synthesis and Characterization of New Adhesion Promoter for Grafting Conducting Polymer on Oxide Substrate

For grafting polypyrrole layers on oxidic substrates, the synthesis and characterization of a new adhesion promoter 11‐(pyrrol‐3‐yl) undecyl trimethoxysilane (PyTMS) were described in this article. The oxidation potential of PyTMS was determined by cyclic voltammetry. The grafting behavior of such an adhesion promoter on oxidized surface and chemical deposition of polypyrrole over the modified oxidized surface were studied. The adsorbed layer on the oxidized substrates thus formed was determined by both contact angle measurements and X‐ray photoelectron spectroscopy. Chemical polymerization of terminal pyrrole moieties on such substrates yielded adhesive polypyrrole films, and SEM image showed that the morphology of the polypyrrole films was influenced by the experimental conditions.     

酚醛树脂层压基板真空热裂解产物分析表征

利用程序升温的热解炉反应器对酚醛树脂层压基板进行真空热裂解,通过元素分析、傅里叶红外(FT-IR)分析和气相色谱-质谱(GC-MS)分析,对原料及产物油成分进行了表征。研究表明,热解油上层清液主要是一些较易溶于水的物质,如苯酚、甲酚、二甲酚、糖类、乙内酰脲类、吗啉类、吡喃酮类和吡啶类化合物等;而下层沉淀则主要为不溶或难溶于水的物质,如大取代基酚类(取代基碳原子数≥2)、磷酸三芳基酯类、脂肪酸酯类和腈类化合物等。其中,三聚氰胺在上层清液和下层沉淀中都有较高的含量。     

液体和非晶态NiAl3合金结构的从头算分子动力学模拟

应用从头算分子动力学方法模拟了液体以及淬冷形成的NiAl₃合金体系,得到了它们的对相关函数、结构因子、键对分析信息.结果分析表明,在淬冷条件下得到的体系呈现非晶态性质,且非晶态结构类似于液态NiAl₃合金的结构,可以用液体结构近似描述非晶态性质.还进行了电子结构分析,得到液体NiAl₃合金的电子态密度和电荷分布.在液体镍铝合金中,镍为电子受体,部分电子由铝向镍转移,支持了Candy等人的XPS实验结果.镍铝间强烈作用,形成带有弱共价键性质的金属键.镍在合金中相当分散,这能部分解释由淬冷形成的NiAl₃合金制得的骨架镍催化剂活性增强的原因.     

Microchemical Investigation of Archaeological Copper Based Artefacts Disclosing an Ancient Witness of the Transition from the Value of the Substance to the Value of the Appearance

In many Italian archaeological sites dated between the sixth and third centuries BC, unworked lumps of Cu-based materials are sometimes found, the so called Aes Rude, which according to archaeological considerations were appreciated as currency, as a medium of exchange and as a form of saving. The microchemical investigation of these ancient artefacts discloses their nature as apparently not usable for any functional applications or possible use. Indeed, Aes Rude resemble ordinary copper material, but microchemical results indicate that they are constituted by highly ferruginous leaded copper, making them useless for producing other metal objects by means of casting or hot and cold working. Notwithstanding this intrinsic negative feature, the production of these intractable Cu-based alloys was deliberately carried out to maximise the process yield in terms of produced metal from an impure and unselected metal ore by tailoring the smelting process parameters. With these considerations in mind, the microchemical investigation of these ancient iron–copper alloys gives evidence of the passage from the acceptance of an artefact value based on its true nature or potential use to the acceptance of the value based only on its appearance or form irrespective of its present or future use. This information could contribute to a better understanding of the evolution of human thought and economic and social interactions.     

Dual mechanism of hydrogen desorption from palladium alloys postulated on the basis of cyclic voltammetric studies

The process of hydrogen absorption/desorption in Pd-Pt and Pd-Pt-Rh alloys has been investigated using cyclic voltammetry. Hydrogen absorbed at constant potential was electrooxidized at various scan rates. The charge of hydrogen oxidation has been found to be dependent on the scan rate. The decrease in the oxidation charge observed for low scan rates indicates that, under these conditions, some amount of hydrogen may be removed via a non-electrochemical recombination reaction. The results suggest that the dual mechanism of hydrogen desorption, involving electrochemical oxidation and non-electrochemical recombination, confirmed for pure palladium, is valid also for palladium alloys.Contribution to the 3rd Baltic Conference on Electrochemistry, GDASK-SOBIESZEWO, 23–26 APRIL 2003.Dedicated to the memory of Harry B. Mark, Jr. (February 28, 1934–March 3rd, 2003)     

Synthesis of an enzyme-like imprinted polymer with the substrate as the template, and its catalytic properties under aqueous conditions

Transition state analogues (TSAs) have long been regarded as ideal templates for the preparation of catalytically active synthetic imprinted polymers. In the current work, however, a new type of molecularly imprinted polymer (MIP) was synthesized with the substrate (homovanillic acid, HVA) as the template and hemin introduced as the catalytic center, with the use of plural functional monomers to prepare the active sites. The MIP successfully mimicked natural peroxidase, suggesting that it may not be imperative to employ a TSA as the template when preparing enzyme-like imprinted polymers and that the imprinted polymer matrix provided an advantageous microenvironment around the catalytic center (hemin), essentially similar to that supplied by apo-proteins in natural enzymes. Significantly, by taking advantage of the special structure of hemin and multiple-site interactions provided by several functional monomers, the intrinsic difficulties for MIPs in recognizing template molecules in polar solutions were overcome. The newly developed polymer showed considerable recognizing ability toward HVA, catalytic activity, substrate specificity and also stability, which are the merits lacked by the natural peroxidase. Meanwhile, the ease of recovery and reuse the MIP implies the potential for industrial application.