Development of an efficient enrichment system for copper determination in water and food samples based on p-phenylenediamine anchored magnetic titanium dioxide nanowires

In the present work, titanium dioxide nanowires (TNWs) were synthesised via hydrothermal method. Insertion of ZnFe₂O₄ nanoparticles to the surface of TNWs was done by sol gel combustion synthesis of the nanoparticles in the presence of the nanowires. The surface of prepared magnetic TNWs was modified by p-phenylendiamine and then it was used in preconcentration of Cu²⁺ ion prior to their determination by flame atomic absorption spectroscopy. The sorbent was characterised by Fourier transform infrared spectra, EDX, FE-SEM and VSM techniques. We investigated and optimised various parameters influencing the preconcentration efficiency, such as the media pH, adsorbent quantity, contact time, sample volume and elution conditions. Under optimum conditions, the analytical performance of the method was evaluated. The calibration curve was found to be linear from 10.0 to 150 μg L^?1 (R² = 0.996). Calculated limit of detection was 0.43 μg L^?1 (n = 5). The estimated relative standard deviation was 2.50% (n = 5). Moreover, the maximum adsorption capacity of the sorbent was 51.5 mg g^?1 and preconcentration factor was 125. Capability of developed method was proved by applying it for preconcentration of Cu²⁺ ion from food and water samples.     

Highly diastereo- and enantioselective cyclopropanation of 1,2-disubstituted alkenes

A helping hand: A series of bis(oxazoline) ligands, which contain pendant C(2) -symmetry-breaking groups, for the Cu-catalyzed asymmetric cyclopropanation of 1,2-disubstituted alkenes has been developed. Under mild reaction conditions, both cis- and trans-1,2-substituted alkenes can be converted into the corresponding 1,2,3-trisubstituted cyclopropanes with high levels of diastereo- and enantioselectivity.     

电感耦合等离子体质谱(ICP-MS)法测定地质样品中Cu和Zn的干扰研究

电感耦合等离子体质谱(ICP-MS)法标准模式测定地质样品中Cu和Zn时,样品溶液中Ti在高温下易形成TiO⁺和TiOH⁺产生离子重叠干扰,使测定值偏离真值而影响测定结果。采用氢氟酸-高氯酸-硝酸消解、王水复溶样品,通过多级在线校正⁴⁶Ti¹⁶O⁺,消除TiO⁺和TiOH⁺离子重叠干扰,研究了单质Ti与⁴⁶Ti¹⁶O⁺、质荷比63、64、65、66离子间存在的关系,建立了一种电感耦合等离子体质谱(ICP-MS)法测定地质样品中Cu和Zn的分析方法。结果表明：单质Ti对Cu和Zn产生的干扰值与其质量浓度呈非简单的正相关性,TiO⁺产生的干扰离子质荷比65离子强度比63高,质荷比64离子强度比66高;⁴⁶Ti¹⁶O⁺对质荷比63、66离子干扰增量值与单质Ti质量浓度变化无关;^6...     

白血病患儿体内铜锌代谢的动态观察

对白血病患儿体内血清锌、血清铜浓度以及血清铜/锌比值作了初步的观测.在41例白血病患儿和33例正常对照儿童中,观察到在明确诊断化疗前,41例白血病患儿中有20例患儿的血清锌浓度低于正常低限,他们的平均血清锌浓度为12.3±3.4 μmol/L,明显低于对照组18.3±4.0 μmol/L.白血病患儿的血清铜/锌比值为1.40±0.38,明显高于正常儿童1.19±0.25.经治疗后,有12例患儿获缓解并继续随访至发病后6～8周,平均血清锌浓度由11.4±2.2μmol/L,提高到13.7±2.1μmol/L,血清铜/锌比值由1.51±0.36,下降到1.29±0.23.说明白血病患儿体内存在着锌代谢的异常.     

厌食症儿童发锌铜含量测定

用原子吸收分光光度法测定了５２例厌食症儿童头发中锌、铜的含量,结果表明,厌食症儿童发一明显地对照组。发铜与对照这间无差异。提示厌食症与缺锌有密切关系。     

Mechanism of the intramolecular hydroamination of alkenes catalyzed by neutral indenyltitanium complexes: a DFT study

Three mechanistic pathways for the [Ind(2)TiMe(2)]-catalyzed intramolecular hydroamination of alkenes have been investigated by employing density functional theory calculations on the possible intermediates and transition states. The results indicate that the reaction cycle proceeds via a Ti-imido-amido complex as the catalytically active species. However, at the moment, the question as to whether this imido-amido complex is involved in a [2+2]-cycloaddition with the alkene or a newly proposed insertion of the alkene into a Ti--N single bond cannot be answered; the calculated barriers of both the insertion mechanism and the [2+2]-cycloaddition mechanism are similar (143 vs. 136 kJ mol(-1)), and both pathways are in accordance with the experimentally observed rate law (first-order dependence on the aminoalkene concentration). Interestingly, the newly proposed insertion mechanism that takes place by an insertion of the alkene moiety into the Ti--N single bond of an imido-amido complex seems to be much more likely than a mechanism that involves an alkene insertion into a Ti--N single bond of a corresponding trisamide. The latter mechanism, which has been proposed in analogy to rare-earth-metal-catalyzed hydroamination reactions, can be ruled out for two reasons: a surprisingly high activation barrier (164 kJ mol(-1)) and the fact that the rate-limiting insertion step is independent of the aminoalkene concentration. This is in sharp contrast to the experimental findings for indenyltitanium catalysts.     

二氰基二硫纶·联吡啶锦（Ⅱ）、铜（Ⅱ）、锌（Ⅱ）配合物的合成与表征

以ｃｉｓ－１，２－二氰基乙烯－１，２－二硫醇钠Ｎａ２（ｍｎｔ）和２，２＇－联吡啶金属配合物Ｍ（ｂｕｙ）Ｃｌ２为原料，合成了标题配合物Ｍ（ｍｎｔ）（ｂｐｙ），Ｍ＝Ｎｉ（Ⅱ）、Ｃｕ（Ⅱ）、Ｚｎ（Ⅱ），并经元素分析、热谱、摩尔电导、红外和电子光谱所表征．三者均为四配位的电中性配合物，热分解温度高于３１０℃，可溶于ＤＭＦ、ＤＭＳＯ、吡啶、氯仿和丙酮，难溶于水和乙醚．     

4776例儿童头发锌、铜含量的回顾性评价

对４７７６例９个月至４岁儿童发锌,铜含量进行了检测分析,发现有半数以上儿童发锌降低,约三分之一儿童发铜减少。     

石英粉尘肺损伤大鼠肺脏、脾脏微量元素锌、铜、镁含量的测定

为探讨石英粉尘（SiO2) 对大鼠肺脏及脾脏微量元素锌，铜，镁含量的影响作用，将雄性Wistar大鼠随机分为两组，实验结束后分别测定大鼠肺脏和脾脏微量元素锌，铜，镁含量。结果表明，SiO2组与对照组比较，脾脏，肺脏锌，镁含量下降，铜含量上升（P＜0．05）。提示SiO2能使肺脏受到损伤，并引起机体微量元素失衡，使脾脏亦受到损伤，造成机体免疫功能下降。     

二硫化碳对机体铜、锌水平的影响

为观察二硫化碳（CS2）对机体铜，锌水平的影响，对某化纤厂35名接触CS2工人和41名非接触工人的血铜，锌值进行调查，比较，并进行了动物染毒实验。SD大鼠吸入CS2浓度分别为5和50mg/m^3，每日5h，每周6d，连续6个月，于染毒2，4，6个月时测定血浆铜，锌值及染毒6个月时肝脏铜，锌含量。结果显示，CS2接触组工人血铜，锌水平较对照组显著降低（P＜0．05）。在CS2染毒6个月时，50mg/m^3 CS2染毒组血浆及肝脏铜水平均较对照组及5mg/m^3 CS2染毒组显著降低（P＜0．05）。可见接触CS2能干扰机体铜，锌代谢，导致体内铜，锌含量减少。     

Physico-chemical characterization of thermal decomposition course in zinc nitrate-copper nitrate hexahydrates

This study reports experimental investigations by non-isothermal TG/DSC analysis of Zn(NO₃)₂·4H₂O, Cu(NO₃)₂·4H₂O and their mixtures of known compositions in the temperature range 30–1200°C. Solid/liquid transitions in the sealed samples of the hexahydrate salts and their mixtures were also studied by DSC in the temperature range 0–60°C. The mixture with composition 0.85Zn(NO₃)₂·6H₂O+0.15Cu(NO₃)₂·6H₂O showed single melting peak at 29°C. This mixture was chosen for detailed studies. Melting temperature and heat of fusion of single salt hexahydrates and of the mixture were calculated from DSC endotherms. The different stages in the thermal decomposition processes have been established. The intermediate and the final solid products of the thermal decomposition were analyzed by XRD. The scheme and the decomposition temperature depended on the composition of the starting material. The final decomposition products were CuO (monoclinic), Cu₂O (cubic), ZnO (hexagonal) and their mixtures with the defined crystalline structures. Possible influence of the addition of CuCl₂·2H₂O into the mixture 0.85Zn(NO₃)₂·6H₂O+0.15Cu(NO₃)₂·6H₂O and a gel combustion technique of the precursor preparation, on the composition and morphology of the solid decomposition products, were also studied. The gel combustion technique, using citric acid added to a mixture of 0.85Zn(NO₃)₂·6H₂O+0.15Cu(NO₃)₂·6H₂O, was applied in an attempt to obtain mixed Zn/Cu oxides of a particular mole ratio. The morphology of the solid decomposition products was examined by SEM.     

慢性前列腺炎及其不育患者精液铜、锌元素的初步研究

慢性前列腺炎是男性中一种常见的疾病。会造成男性生育力的降低。本文对6例无生育力和18例有生育力的慢性前列腺炎患者精液中铜，锌元素进行了检测。结果表明，天生育力的患者精液中铜，锌含量与有生育力患者的含量无显著差异。所以，慢性前列腺炎不育与精液中铜，锌含量无相关性存在。     

用炼锌厂废泥制取硫酸铜、海绵镉和硫酸锌

研究了以炼锌厂废泥为原料,经氧化、酸浸、中和沉淀、稀硫酸溶解、置换等步骤制取硫酸铜、海绵镉和硫酸锌的工艺.