Monitoring of the exposure to platinum-group elements for two Italian population groups through urine analysis

It is well recognized that automobile catalytic converters are the main source of Pd, Pt and Rh (also called platinum-group elements (PGEs)) in an urban atmosphere. Over recent years, urinary biomonitoring of PGEs has gained considerable importance in assessing the individual human exposure to these elements. This paper reports the concentration ranges of PGEs in the urine of 257 Italian subjects, aged between 23 and 88 years. Subjects were selected on the basis of standardized criteria in two different Italian cities, so as to represent a small urban area surrounded by an essentially rural environment and characterized by low automobile-traffic density (Foligno) and a large urban area with almost constant high-traffic conditions (Rome). The determination of PGEs was performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) after 1:4 (v/v) dilution of the samples. The 5th and 95th percentiles for PGEs in urine of subjects living in Foligno were the following (in ng l⁻¹): Pd 1.99-17.2, Pt 0.24-3.08 and Rh 0.53-14.8. The 5th and 95th percentiles in the urine of subjects from the area of Rome were (in ng l⁻¹): Pd 0.71-17.0, Pt 0.49-8.13 and Rh 4.10-38.6. Platinum and Rh median concentration values showed large and significant differences (P<0.0001) between the two urban settings considered (0.52 and 3.50 ng l⁻¹ for Pt and Rh in Foligno, respectively, and 1.70 and 12.85 ng l⁻¹ for Pt and Rh in Rome, respectively). On the other hand, no striking differences were found in the Pd concentration (median value of 6.02 ng l⁻¹ in Foligno versus 7.79 ng l⁻¹ in Rome). The sex variable correlates only with Pd concentration (P=0.05), pointing out that in males concentrations are higher than in females.     

Synthesis of nickel sulfide and nickel–iron sulfide nanoparticles from nickel dithiocarbamate complexes and their photocatalytic activities

[ Ni(dtc)₂] (dtc = N-(pyrrole-2-ylmethyl)-N-thiophenemethyldithiocarbamate ( 1 ), N-methylferrocenyl-N-(2-phenylethyl)dithiocarbamate ( 2 ), N-furfuryl-N-methylferrocenyldithiocarbamate ( 3 ), and (N-[pyrrole-2-ylmethyl]-N-thiophenemethyldithiocarbamato-S,S′)(thiocyanato-N)(triphenylphosphine)nickel(II) ( 4 ) complexes were prepared and characterized by elemental analysis, infrared, ultraviolet–visible, and nuclear magnetic resonance (¹H and ¹³C) spectroscopies. The data were consistent with the formation of square planar nickel(II) complexes, which was confirmed by single-crystal X-ray diffraction studies on 2 and 4 . Fe···Fe interactions exhibited by complex 2 led to supramolecular aggregation. The structure of 4 reveals intermolecular and intramolecular C-H···Ni anagostic interactions. The anion-sensing properties of 2 were studied with halide ions by cyclic voltammetry. It was observed that 2 acts as sensor for bromide. Complexes 1 , 2 , and 3 , were utilized to prepare nickel sulfide, nickel–iron sulfide-1, and nickel–iron sulfide-2, respectively. The composition, structure, morphology, and optical properties of nickel sulfide and nickel–iron sulfides were examined using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, ultraviolet–visible, fluorescence, and infrared spectroscopy. Powder X-ray diffraction patterns of nickel sulfide, nickel–iron sulfide-1, and nickel–iron sulfide-2 indicate the formation of orthorhombic Ni₉S₈, cubic NiFeS₂, and cubic Ni₂FeS₄, respectively. The photocatalytic activities of as-prepared nickel sulfide and nickel–iron sulfide-1 nanoparticles were investigated for photodegradation of methylene blue and rhodamine-B under ultraviolet irradiation. Nickel–iron sulfide-1 nanoparticles show slightly higher photodegradation efficiency compared with the nickel sulfide nanoparticles.     

Controllable synthesis of nickel hydroxide and porous nickel oxide nanostructures with different morphologies

Alpha-Ni(OH)(2) nanobelts, nanowires, short nanowires, and beta-Ni(OH)(2) nanoplates have been successfully prepared in high yields and purities by a convenient hydrothermal method under mild conditions from very simple systems composed only of NaOH, NiSO(4), and water. It has been found that the ratio of NaOH to NiSO(4) not only affects the morphology of the Ni(OH)(2) nanostructures, but also determines whether the product is of the alpha- or beta-crystal phase. A notable finding is that porous NiO nanobelts were produced after exposure of the Ni(OH)(2) products to an electron beam for several minutes during transmission electron microscopy (TEM) observations. Another unusual feature is that rectangular nanoplates with many gaps were obtained. Furthermore, porous NiO nanobelts, nanowires, and nanoplates could also be obtained by annealing the as-prepared Ni(OH)(2) products. A sequence of dissolution, recrystallization, and oriented attachment-assisted self-assembly of nanowires into nanobelts is proposed as a plausible mechanistic interpretation for the formation of the observed structures. The method presented here possesses several advantages, including high yields, high purities, low cost, and environmental benignity. It might feasibly be scaled-up for industrial mass production.     

Comparison of PBDE congener profiles and concentration levels in human specimens from China and the US and identification of human exposure sources

In an effort to investigate the status of human exposure to PBDEs in China,available monitoring data in human specimens(including breast milk,serums,and blood) was collected from the general population as well as specific groups that are occupationally exposed.PBDEs exposure profiles and concentration levels were compared with their counterparts in the United States of America.It was found that PBDE burdens in general Chinese population are one order lower and have different congener profiles from that in t...     

对羟基苯甲酸酯类防腐剂的人体暴露

在过去50年中,对羟基苯甲酸酯类防腐剂(parabens)被广泛用于食品、药品和化妆品的生产中.常用的parabens包括对羟基苯甲酸甲酯、乙酯、丙酯、丁酯、异丙酯和异丁酯.此类防腐剂已在人体血液和尿液中广泛检出,在人体内主要以代谢物对羟基苯甲酸的形式存在.研究表明,该类防腐剂可能与乳腺癌的发病有关,动物实验表明该类防腐剂可能具有雌激素活性,因此其在环境介质和人体组织中的残留、污染和毒性受到广泛关注.本文综述了parabens在体外暴露(食品、药品、化妆品、空气、灰尘、水和土壤)和体内暴露(血液、尿液、脂肪组织)方面的最新研究进展,总结了不同环境介质和人体组织中parabens的含量水平以及暴露量,对体外暴露和体内暴露进行了比较,探讨了parabens人体暴露的主要途径.最后对parabens研究的发展趋势进行了展望.     

Ball-milling processing of nanocrystalline nickel hydroxide and its effects in pasted nickel electrodes for rechargeable nickel batteries

Nanocrystalline Ni(OH)₂ powder synthesized by a chemical precipitation method was processed using the planetary ball milling (PBM), and the physical properties of both the ball-milled and unmilled Ni(OH)₂ were characterized by scanning electron microscopy (SEM), specific surface area, particle size distribution, and X-ray diffraction. It was found that the PBM processing could significantly break up the agglomeration, uniformize the particle size distribution, increase the surface area, decrease the crystallite size, and reduce the crystallinity of nanocrystalline β-Ni(OH)₂, which were advantageous to the improvement of the electrochemical activity of Ni(OH)₂. The ball-milled nanocrystalline (BMN) Ni(OH)₂ was then used to alter the microstructure of pasted nickel electrodes and improve the distribution of the active material in the porous electrode substrate. Electrochemical performances of pasted nickel electrodes with a mixture of BMN and spherical Ni(OH)₂ as the active material were investigated, and were compared with those of pure spherical Ni(OH)₂ electrodes. Charge/discharge tests showed that BMN Ni(OH)₂ addition could enhance the charging efficiency, specific discharge capacity, discharge voltage, and high-rate capability of pasted nickel electrodes. This performance improvement could be attributed to a more compact electrode microstructure, better reaction reversibility, and lower electrochemical impedance, as indicated by SEM, cyclic voltammetry, and electrochemical impedance spectroscopy. Thus, it was an effective method to modify the microstructure and improve the electrochemical properties of pasted nickel electrodes by adding an appropriate amount of BMN Ni(OH)₂ to spherical Ni(OH)₂ as the active material.     

Using Ho3+ Fluorescence Enhancement as a Novel Probe in Monitoring of Human Serum Albumin

Abstract

In this work, for the first time, the fluorescence enhancement of Ho³⁺ ions is introduced as a novel probe for human serum albumin (HSA) determination in aqueous solution. Lanthanides express very specific luminescence emissions, due to their unfilled 4fⁿ electronic orbital, and thus, the fluorescence of the lanthanide ions can be radically improved when they are coordinated with the appropriate organic molecules. By applying this method, HSA can be determined up to 0.066 mg L^?1.     

A new approach to nickel electrolytic colouring of anodised aluminium

Energy dispersive X-ray spectroscopy and scanning electron microscopy were used to analyse nickel on anodic aluminium surfaces after stripping the anodic aluminium oxide. The metal was electroplated at the bottom of the pores of anodised aluminium during electrolytic colouring in solutions without (Watts) and with (citrate) complexing agents, respectively. A relation between the anodic-cathodic processes, changes of the structure and composition of the coating in dependence on the used solution were studied. A morphology study performed after stripping the anodic aluminium oxide revealed the crucial influence of the anodic process/cycle and the complexing agent on the nickel structure on the aluminium surface. Off-time of half-way rectified current influenced the nickel deposition in the pores of anodic alumina negatively.     

UV photosynthesis of nickel carbonyl

In the presence of low‐molecular‐weight organic acids, such as formic, acetic, and propionic, inorganic nickel salts in aqueous solutions are converted to the volatile tetracarbonyl by UV irradiation. Experiments were performed using a flow‐through photoreactor, consisting of a 6 m length polytetrafluoroethylene tubing wrapped around a low‐pressure mercury vapor UV lamp (254 nm, 15 W). The efficiency of transformation was estimated to be 95%. As no carbon monoxide or external reductant is required, photochemical synthesis may prove to be useful in material chemistry and applicable to the extractive metallurgy of nickel, as well as its refining and recycling. Copyright © 2004 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

Oligomerization of ethylene to branched alkenes using neutral phosphinosulfonamide nickel(II) complexes

A series of neutral phosphinosulfonamide complexes of nickel(II) were synthesized that catalyzed the oligomerization of ethylene to branched oligomers with average degrees of polymerization between 10 and 35. Branching numbers varied from 17 to 80 branches per 1000 carbons, depending on the catalyst structure and reaction conditions. The catalysts were active in a variety of solvents, including toluene, CH₂Cl₂, tetrahydrofuran, ethyl acetate, and methanol, but showed decreasing activity at temperatures higher than 40 °C. Electron‐rich phosphinosulfonamides produced the highest catalyst activities in a series of structure–reactivity studies. The mechanism of oligomer formation was investigated with ¹H NMR spectroscopy, which indicated that branching arose from the isomerization of the nickel alkyl species during propagation rather than the reincorporation of α‐olefin products. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4627–4640, 2000     

Hydrogenation of nitrobenzonitriles using Raney nickel catalyst

2-, 3-, 4-Nitrobenzonitriles were hydrogenated using Raney nickel catalyst in the environment of two different solvents (methanol and dioxane). The position of the nitro group relative to the nitrile group plays the dominant role in the course of hydrogenation. The nearer the substituent to the nitrile group is, the larger is its effect. 3- and 4-nitrobenzonitriles were hydrogenated to their primary amines, in contrast to 2-nitrobenzonitrile, which was transformedvia intramolecular oxidation to 2-aminobenzamide. During hydrogenation, numerous intermediates were formed. The choice of the solvent is another significant parameter affecting the course of hydrogenation.     

Na2EDTA反滴定法测定铜镍合金中的镍

采用Na2EDTA返滴定法测定铜镍合金中的镍含量, 用柠檬酸钠、硫代硫酸钠和酒石酸做掩蔽剂,丁二酮肟沉淀分离,以二甲酚橙为指示剂,加入过量的Na2EDTA,用氯化锌标准溶液返滴定。方法能很好地分离铜及其他杂质的干扰。试验方法用于测定铜镍合金中的镍含量,测定结果的相对标准偏差（RSD,n=9）为0.0456%～0.2409%,加标回收率为99.30%～101.10%如有残渣,过滤之后将残渣消解,用光谱测定不溶渣中的镍含量。能够满足日常样品的检测要求。     

泡沫镍及负载型镍催化剂制备纳米碳纤维层的研究

纳米碳纤维可用在催化材料、储氢材料、及纳米电子器件等方面。本文对用泡沫镍及负载型镍催化剂催化分解乙烯或丙烯制备纳米碳纤维进行了研究。利用X射线衍射仪、物理吸附仪、扫描电镜进行了分析表征,并考察了催化剂、碳源、生长温度对纳米碳纤维生长量、形貌、结构的影响。结果表明:在生长温度450℃,乙烯流率30mL/m in的条件下,负载型镍催化剂纳米碳纤维的生长量要高出泡沫镍3~6倍,负载型镍催化剂制备的纳米碳纤维直径为40~60纳米,小于泡沫镍的情况。泡沫镍催化分解乙烯制备纳米碳纤维时,纳米碳纤维的生长量和平均直径随温度的降低而逐渐减小。纳米碳纤维在泡沫镍上的最低生长温度为420℃,在低于480℃生长纳米碳纤维时泡沫镍的骨架结构不会被破坏,由此制备的纳米碳纤维在新型结构催化材料中有很好的的应用前景。     

Partial oxidation of methane to syngas catalyzed by a nickel nanowire catalyst

A nickel nanowire catalyst was prepared by a hard template method,and characterized by transmission electron microscopy (TEM),N2 physical adsorption,X-ray photoelectron spectrometry (XPS),X-ray diffraction (XRD) and H2 temperature-programmed reduction (H2-TPR).The catalytic properties of the nanowire catalyst in the partial oxidation of methane to syngas were compared with a metallic Ni catalyst which was prepared with nickel sponge.The characterization results showed that the nickel nanowire catalyst had high specific surface area and there was more NiO phase in the nickel nanowire catalyst than in the metallic Ni catalyst.The reaction results showed that the nickel nanowire catalyst had high CH4 conversion and selectivities for H2 and CO under low space velocity.     

Characterization of the decomposition course of nickel acetate tetrahydrate in air

Thermogravimetry, differential thermal analysis, X-ray diffractometry and infrared spectroscopy showed that Ni(CH₃COO)₂·4H₂O decomposes completely at 500°C, giving rise to a mixture of Ni^o and NiO. The results revealed that the compound undergoes dehydration at 160°C and melts at 310°C. The water thus released hydrolyses surface acetate groups, acetic acid being evolved into the gas phase. At 330°C, the anhydrous acetate is converted into NiCO₃, releasing CH₃COCH₃ into the gas phase. The carbonate subsequently decomposes (at 365°C) to give NiO_(s), CO_2(g) and CO_(g). On further heating up to 373°C, a mixture of Ni^o and NiO is formed. Other gas-phase products were detected at 400°C, viz. CH₄ and (CH₃)₂CH=CH₂, which were formed in surface reactions involving initial gas-phase products. Non-isothermal kinetic parameters (A and ΔE) were calculated on the basis of temperature shifts experienced in the various decomposition processes as a function of heating rate (2–20 deg·min^?1).     

电化学合成镍配合物的研究

采用金属镍为“牺牲”阳极，首次在无隔膜电解槽中，电化学溶解金属镍一步 制备了纳米NiO前驱体Ni(Oet)2,Ni(Obu)2,Ni(Oet)2(acac)2，Ni(Obu)2(acac)2 [acac为乙酰丙酮基].产物通过红外光谱（FT-IR）、拉曼光谱（Raman spectrum） 进行表征。同时讨论了影响电合成镍醇盐及其配合物的关键因素。实验表明，防止 阳极钝化，温度控制在30-40℃，采用有机胺溴化物为导电盐，可以提高电合成效 率。     

Conjugate additions of cyclic oxygen-bound nickel enolates to alpha,beta-unsaturated ketones

The reaction of nickel enolates displaying a metallacyclic structure with the alpha,beta-unsaturated ketones methyl vinyl ketone (MVK) or methyl propenyl ketone (MPK) takes place in two stages, affording initially bicyclic adducts, which subsequently isomerize to the corresponding open-chain products. The former are generated with high stereoselectivity and can be considered as the products of the [2+4] cycloaddition of the enolate to the enone. The ring opening process involves a prototropic rearrangement that can be catalyzed by water. In the case of the reaction of the parent nickel enolate complex 1 (which displays an unsubstituted Ni-O=C(R)CH2 arrangement) with MVK, a double-addition process has been observed, consisting of two successive cycloaddition/isomerization reactions. The carbonylation of the different cyclic and noncyclic products affords the corresponding lactones that retain the stereochemistry of the organometallic precursors. This methodology allowed trapping the primary product of the reaction of 1 with MPK as the corresponding organic lactone, demonstrating that the cycloaddition process takes place with exo selectivity. DFT modeling of the latter reaction provides further support for a quasi-concerted cycloaddition mechanism, displaying a nonsymmetric transition state in which the C-C and the C-O bond are formed in an asynchronous manner.     

Template electrosynthesis of complexes of nickel with schiff bases

A suitable method is proposed for the electrosynthesis of complexes of nickel with Schiff bases containing a hydroxyl group (homogeneous catalysts of chemical and electrochemical reactions) in a single stage with a high material yield.A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1435–1437, June, 1992.