The effect of Cs ions on codeposition of SiC particles with nickel

Electrodeposition of SiC particles (technical powder) with nickel matrix in the presence of cesium ions (0–37.6 mM) was investigated. The influence of Cs⁺ concentration on cathodic polarization curves was determined in galvanostatic and potentiodynamic measurements. The presence of Cs⁺ in the solution enhanced in some extent adsorption of Ni²⁺ ions on SiC, but preferential cesium adsorption occurred simultaneously. The last phenomenon resulted in cesium incorporation in the composite coating. The particle content in the deposits (16–24 vol%) was governed by the amount of nickel ions adsorbed on SiC. Structure of the composite coatings was studied by microscopic observations. At highest Cs⁺ concentrations, incorporation of small SiC grains was inhibited. Microhardness of deposits (390–800 HV) was directly dependent on the SiC content in the coatings.     

The effect of antibacterial agents on the behaviour of cultured mammalian fibroblasts

Wound infections retard healing rates and can lengthen the time a patient is required to spend in hospital. Obviously it is desirable to minimize or remove pathogenic organisms to allow wound healing to progress optimally. At present there are a large range of topical applications available in the form of antibiotics or antiseptics, but the toxic effects of these agents may outweight the benefits. In this study two conventional antiseptic agents were examined together with a range of phosphate-based glasses which were designed to release metal ions into an aqueous environment. As a control a series of standard metal ion solutions were prepared and examined in the same test system. The metal ions examined are considered important in the wound healing environment either for their potential bacteriostatic effects or indeed their potential for increasing cellular activity. This part of the study examined the effects of these agents on mammalian cells in vitro, using a standard MTT assay to assess the cytotoxicity or activity of cultured mouse fibroblasts. It was found that chlorhexidene, a commonly used antiseptic agent, was toxic at low levels. The controlled release glasses, in most cases, increased the rate of cell activity before reaching toxic levels. This effect was also found with the standard metal solutions.     

In vitro cellular uptake and cytotoxic effect of functionalized nickel nanoparticles on leukemia cancer cells

Nickel nanoparticles (Ni NPs) have been applied in a wide range of areas because of their unique structure and properties such as catalysts, high-density magnetic recording media and others. However, little effort has been paid to their biological application and the concrete effect of Ni NPs on biological systems is still unknown. In this study, the possibility of the utilization of the magnetic Ni NPs in cancer cell studies was explored and the effects of the Ni NPs capped with positively charged tetraheptylammonium on leukemia K562 cells in vitro were investigated. Our observations of optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM) studies indicate that the morphological changes of cancer cells induced by Ni NPs could be apparently observed. The results of 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) assay, DNA fragmentation and flow cytometry studies demonstrate that the Ni NPs could exert cytotoxicity to leukemia K562 cells at high concentration, and subsequently induce both apoptosis and necrosis of target cancer cells, whilst it had little impact on target cells when at low concentration. Meanwhile, functionalized Ni NPs with positively charged groups could enhance the permeability of cell membrane and facilitate the cellular uptake of outer target molecules into cancer cells. These findings reveal the potential mechanism of Ni NPs to target cancer cells which could induce the cytotoxicity to leukemia cancer cells and suggest the possibility for applications of the Ni NPs in related clinical and biomedical areas.     

Preparation of orpiment nanoparticles and their cytotoxic effect on cultured leukemia K562 cells

An investigation has been made into the antitumor effect on K562 cells of orpiment nanoparticles which were prepared chemically and analyzed by transmission electron microscope and energy dispersive spectrometry (EDS). Methyl thiazolyl tetrazolium and flow cytometry assays were performed to examine their antitumor effect compared with that of traditional orpiment at various concentrations. The average diameters of the two types of orpiment nanoparticles prepared were 60 nm and 140 nm, respectively, and EDS identified that only orpiment was present. Orpiment nanoparticles greatly inhibited the proliferation of K562 cells by apoptosis, in a concentration-and time-dependent manner, much more effectively than traditional orpiment (p < 0.001). The survival ratio of cells treated with orpiment nanoparticles at 2, 4, 8, and 16 micromol/l after 72 h was 23.0%, 10.1%, 3.2%, and 0.5%, respectively, much lower than 80.0%, 69.0%, 52.3%, and 31.7% of cells treated with traditional orpiment at the corresponding concentration for 72 h. The IC50 of orpiment nanoparticles in K562 cells for 48 h was only 1.27 micromol/l, in comparison with 13.0 micromol/l of traditional orpiment. After treated with orpiment nanoparticles at 4, 8, and 16 micromol/l for 48 h, the apoptotic rate of cells was 11.55%, 20.70%, and 26.45%, respectively, but that in cells treated with traditional orpiment at the same concentration for 48 h was only 3.16%, 3.86%, and 6.46%, respectively. Thus, orpiment nanoparticles can produce a much better cytotoxic effect on cancer cells than that of traditional orpiment.     

Influence of nickel ions on human multipotent mesenchymal stromal cells (hMSCs)

Nickel‐Titanium‐Shape‐Memory‐Alloys (NiTi‐SMA) are of biomedical interest due to an unusual range of pure elastic deformability (superelasticity) and the shape memory effect which allows this material to return to a predictable previously memorized shape after external changes in temperature. HMSCs (human multipotent mesenchymal stromal cells) are currently the most promising cell type for regenerative medicine and tissue engineering, due to the ability to differentiate into several tissues such as bone, tendon, cartilage or muscle. For tissue engineering newly developed porous NiTi‐SMA materials are evaluated preloaded with hMSCs. For biocompatibility testing the high nickel content (50 %at) of NiTi‐SMA plays a critical role. To analyse the influence of Ni‐ions on hMSCs viability and activation, cells were cultured with or without NiCl₂ for 24h and 7days. Cells were either seeded in media containing NiCl₂ or the NiCl₂ was later added to already adherent cells. Cell metabolism, proliferation and viability were analysed by alamarBlue^TM assay or fluorescence microscopy. Cytokine (IL‐6, 8, 11) release from hMSCs was determined by ELISA . NiCl₂ concentrations below 25 μg/ ml were well tolerated by the cells. A significant decrease in cell proliferation occurred at threshold values of 200 μg/ ml (24 h) and 25 μg/ ml (7 d). There was a significant, dose dependent increase in the release of IL‐8 from hMSCs cultured in the presence of sub toxic NiCl₂ concentrations. The present study demonstrates for the first time that high but non‐toxic concentrations of Ni²⁺ are capable to activate hMSCs. Thus high Ni²⁺ concentrations apart from allergen‐ or particle‐induced inflammation, may lead to tissue inflammation in the vicinity of a NiTi‐SMA implant in vivo and subsequently to implant failure e.g. due to implant loosening.     

Removal of nickel ions from water by multi-walled carbon nanotubes

Multi-walled carbon nanotubes (MWCNTs) were produced by chemical vapor decomposition using acetylene gas in the presence of Ferrocene catalyst at 800 degrees C, and then oxidized with concentrated nitric acid at 150 degrees C. Both (as-produced and oxidized) CNTs were characterized by TEM, Boehm titration, N2-BET and cation exchange capacity techniques. The adsorption capacity for nickel ions from aqueous solutions increased significantly onto the surface of the oxidized CNTs compared to that on the as-produced CNTs. The effects of adsorption time, solution pH and initial nickel ions concentrations on the adsorption uptake of Ni2+ for both the as-produced and oxidized CNTs were investigated at room temperature. Both Langmuir and Freundlich isotherm models match the experimental data very well. According to the Langmuir model the maximum nickel ions adsorption uptake onto the as-produced and oxidized CNTs were determined as 18.083 and 49.261 mg/g, respectively. Our results showed that CNTs can be used as an effective Ni2+ adsorbent due to the high adsorption capacity as well as the short adsorption time needed to achieve equilibrium.     

Electrocatalytic behaviour of titanium implanted with nickel and molybdenum ions

Abstract

The electrocatalytic activity of titanium induced by ion implantation has been investigated. Ion implantation was carried out using a metal vapour vacuum arc source ion implanter at room temperature. Nickel ion implantation was followed by molybdenum ion implantation at doses ranging from 1 × 10¹⁶ to 1 × 10¹⁷ ions/cm² at the same average extracting voltage of 45 kV. The concentration profiles of Ni and Mo ions in the near surface were detected by electron probe microanalysis and X-ray photoelectron spectroscopy. The catalytic behaviour of implanted titanium was determined by an electrochemical method. Potential versus current density curves for the cathodic hydrogen evolution reaction indicated that Ni and Mo ions implanted into titanium electrodes resulted in a low hydrogen overvoltage of 110-180 mV (at a current density of 200-400 mA cm^-2 in 30 wt-%KOH at 25°C) and excellent stability. The electrocatalytic activity induced by ion implantation can be explained provisionally by interactions between Ni and Mo ions and the titanium substrate.     

Studies on nickel coated carbon fibres and their composites

Uniform and continuous coating of nickel was given to the carbon fibres by cementation, electroless or electroplating techniques. The coating thickness was ranged between 0.2 and 0.6 m for all the three methods used. Coating thickness less than 0.2 m showed discontinuous coating of nickel over the fibre surface. Beyond 0.6 m thickness, nickel deposited in den-drite form over the continuous coating. For continuously coated fibres, the ultimate tensile properties of electroless coated fibres were near to uncoated carbon fibres suggesting adherent and defect free coating; while fibres coated by electrolytic and cementation process exhibited lower ultimate tensile strength (UTS) properties. The tensile fracture of the cementation coated fibres suggested degradation of the fibres. In composites, prepared by dispersing the coated fibres in pure aluminium matrix, no appreciable fibre-metal interaction was observed. NiAl₃ intermetallics were observed around and adjacent to the carbon fibres. Sometimes carbon fibres were found embedded in massive NiAl₃ intermetallics suggesting that fibre surface can also act as nucleating centre for these precipitates.     

Selective cytotoxic effect of ZnO nanoparticles on glioma cells

In this study we examined the cytotoxic effect of ZnO nanoparticles on various human cancer and normal cells. We found that the ZnO nanoparticles exerted a cytotoxic effect on the human glioma cell lines A172, U87, LNZ308, LN18, and LN229, whereas no cytotoxic effect was observed on normal human astrocytes. Similarly, the ZnO nanoparticles induced cell death in breast and prostate cancer cell lines while no major effect was observed in the respective normal breast and prostate cell lines. Using the fluorescent dye 2,7-dichlorofluorescein diacetate, we found that treatment of the glioma cells with ZnO nanoparticles induced a large increase in the generation of reactive oxygen species (ROS) and treatment of the cells with N-acetyl cysteine decreased the cytotoxic effect of the ZnO nanoparticles. In contrast, a smaller effect on ROS generation was observed in the normal astrocytes. These results suggest that ZnO nanoparticles may be employed as a selective cytotoxic agent for the eradication of cancer cells.     

The effect of metal ions on neutrophil degranulation

This study examined neutrophil activation, after incubation of these cells with metal ions. Activation was examined using lysozyme and chemiluminescence assays. Cobalt ions (0.5–30 p.p.m.), chromium ions (0.5–20 p.p.m.), nickel ions (1–50 p.p.m.) and aluminium ions (0.05–7.5 p.p.m.) did not stimulate neutrophils to release lysozyme and did not stimulate a respiratory burst. Copper ions (0.25–7.5 p.p.m.) stimulated neutrophils to release lysozyme, a result which was significant at the 5% level. This was not as a result of copper ions causing neutrophils to lyse. Lysozyme secretion was inhibited when neutrophils were pre-incubated with cytochalasin B, although cytochalasin B had no effect on the enzyme secretion due to stimulation by opsonized zymosan and zymosan-activated serum. This suggests that the mechanism by which copper ions stimulate neutrophil degranulation is different from that of opsonized zymosan and zymosan-activated serum. Enzyme secretion was not accompanied by a respiratory burst.     

原子吸收分光光度法测定土壤中的镍的方法研究

本文对微波消解-原子吸收分光光度法测定土壤样品中的镍元素的分析方法进行了探讨,并对不同类型土壤消解后赶酸与不赶酸的测定结果进行了比较。结果表明,原子吸收法测定土壤中的镍必须赶酸,但赶酸的方法可以简化,并利用连续光源原子吸收光谱图进行了验证。     

Studies on Ag and Li ions irradiated LAHCl single crystals

Semi-organic single crystals of LAHCl were grown by unidirectional solution growth method. The grown single crystals were subjected to Ag⁸⁺ and Li⁴⁺ ions irradiation of energy 100 MeV and 50 MeV, respectively. Breaking of bonds in the irradiated LAHCl molecules and the lattice deformations are analyzed by Fourier transform infrared spectroscopy and X-ray diffraction studies, respectively. The modifications induced by ion irradiation in dielectric, mechanical stability and nonlinear optical property are studied at different ion fluence.     

多相氢氧化镍的合成及其性能研究

用液相共沉淀技术制备了具有α-Ni(OH)2和β-Ni(OH)2混合结构的多相氢氧化镍,并且扫描电镜研究了其形貌,用XRD研究了其多相氢氧化镍形成的过程,探讨了在陈化过程中和用0.2C率充放电过程中的结构稳定性,通过充放电测试讨论了其放电性能.结果发现,通过控制掺杂元素和工艺条件,多相氢氧化镍在碱性溶液中结构稳定,充放电过程中能交换1.3个电子,其放电比容量最大可达375mAh/g,放电电位平台比β-Ni(OH)2电极高100mV左右.     

铈元素对镍电极性能的影响

研究了Ce元素作为添加剂，通过外掺和共沉积的方式加到Ni(OH)2时对镍电极性能的影响，并用循环伏安法对结果进行分析，结果表明外掺法极大地提高了电极的性能，而共沉积加入Ce元素却不能有效地改善电极的性能，循环伏安实验结果表明，外掺法加入Ce元素时能够很好地改善电极的可逆性，改善了电极反应中电子的传输能力，因而很好地改善了电极的性能。     

Application of three xanthates collectors on the recovery of nickel and pentlandite in a low-grade nickel sulfide ore using optimum flotation parameters

One of the challenges encountered when processing nickel ore is the presence of other minerals like chalcopyrite, pyrrhotite, pyrite and amphiboles in mineral dressing. Hence, there is need to investigate the selectivity of some collectors at optimum flotation parameters (particle size, milling time, pH and flotation cell) to maximize nickel and pendlandite recovery. Three xanthate collectors, namely potassium amyl xanthate (PAX), sodium isobutyl xanthate (SIBX) and sodium ethyl xanthate (SEX), were investigated in this study. In order to achieve this aim, the physical treatment of nickel sulfide ore and percentage chemical composition of nickel sulfide ore were investigated. The analyses of the concentrates were done using x-ray diffraction (XRD) and x-ray fluorescence spectroscopy (XRF). The optimum nickel and pentlandite recovery was achieved at particle size of 64.73 µm milled for 1.5 h, pH of 9.65 and using a new flotation cell. Also, SEX collector recovered more nickel and pentlandite contents compared to PAX and SIBX collectors when optimum parameters of particle size, milling time, pH and flotation cell were considered. In conclusion, the results showed that the selectivity of SEX is the strongest and will recover more pentlandite in a complex and low-grade nickel sulfide ore.