Hydrothermal-electrochemical deposition of calcium phosphates on various metals.
Calcium phosphates were formed on five kinds of substrate metals using a hydrothermal-electrochemical method in an autoclave with two electrodes. The electrolyte dissolving NaCl, K2HPO4, CaCl2.2H2O, tris (hydroxymethyl) aminomethane, and hydrochloric acid was maintained at 100 degrees C, 150 degrees C and 200 degrees C. The counter electrode, the anode, was platinum plate, 20 x 20 x 0.5 mm, and the working electrodes as cathode were pure titanium, pure zinc, pure nickel, pure iron, and stainless steel plates. A constant direct current at 12.5 mA/cm2 was loaded for 1 hr. Hydroxyapatite [Ca10(PO4)6(OH)2] only deposited at three temperatures on pure titanium plate. On pure zinc plate, both parascholzite [CaZn2(PO4)2.2H2O] and hydroxyapatite were formed at 150 degrees C and both parascholzite and ZnO were formed at 200 degrees C. Both hydroxyapatite and beta-TCP [beta-Ca3(PO4)2] were formed on pure nickel, pure iron, and stainless steel plates at 200 degrees C. It seems that the incorporation of the metal ions released from the electrode decreased the Ca/P ratio of the deposit due to the formation of other compounds except hydroxyapatite. (+info)
XPS study on the weakest zone in the adhesion structure between resin containing 4-META and precious metal alloys treated with different surface modification methods.
Three precious metal alloys, Type IV gold alloy, 14 K gold alloy, and silver-based alloy, were treated with different surface modifications including a metal primer (VBATDT) application, a SiOx coating method, high-temperature oxidation, modification method with a liquid Ga-Sn alloy, and tin electroplating. Then thin PMMA films were bonded with a resin containing 4-META. Water durability at the adhesion interface was evaluated after water immersion, followed by thermal cycling used liquid nitrogen. The weakest zone at the interface was investigated using XPS only for the Ag-Pd alloy specimens that had been surface-treated with as-polishing, adhesive primer, and the SiOx coating method, since peeling of the PMMA film on the surface of specimens surface-treated by other methods was not observed. Metal elements were detected from the resin side at the adhesion interface. The chemical states of Cu in the resin before argon ion etching were characterized as metal oxides and/or states of chemical interaction with 4-META, VBATDT, or SiOx. (+info)
Workers' understanding of chemical risks: electroplating case study.
BACKGROUND: There is limited research concerning how small companies in particular, respond to health and safety messages. AIMS: To understand individuals' knowledge and beliefs about chemical risks and to compare these with those of experts. METHODS: The use of chromic acid in particular, and also other chemicals associated with chrome plating were studied. All chromium plating firms were based in the West Midlands. The methodology involved initial face to face interviews (n = 21) with chromium platers, structured questionnaires (n = 84) to test the prevalence of beliefs identified in the interviews, an expert questionnaire, and a workshop to discuss findings. The responses of platers were compared with those of occupational health and safety experts. RESULTS: Although chromium platers appeared to understand the short term adverse effects of the chemicals to which they are exposed, their understanding of long term, or chronic effects appeared to be incomplete. They had good knowledge of acute effects based primarily on experience. Platers were aware of the hazardous nature of the chemicals with which they work, but did not draw distinction between the terms "hazards" and "risks". They had difficulties articulating the effects of the chemicals and how exposure might occur; although it is inappropriate to equate this with lack of knowledge. A significant minority of platers displayed deficiencies in understanding key technical terms used in Safety Data Sheets. CONCLUSIONS: This study provides a method which can be used to gain some understanding of workers' knowledge and beliefs about risks that they are exposed to in the workplace. The study also identifies gaps between the platers' knowledge and beliefs and those of experts. New risk information needs to be designed which addresses the information needs of platers using language that they understand. (+info)
Calcium-ion incorporation into titanium surfaces accompanied by electrochemical apatite-deposition.
The depths of calcium-ion incorporation into a commercially pure titanium and an experimental beta-type titanium alloy were determined using Auger electron spectroscopy. After the electrochemical deposition of apatite, new compositional gradients appeared in the profiles in which the Ca and P concentrations gradually decreased as a function of the depth up to 6-8 nm. The relative concentration of Ca in the outermost layer was higher than that of P. On the other hand, after the soaking in a simulated body fluid, the relative concentration of P was higher than that of Ca in the outermost layer. These results suggested that Ca ions were well incorporated into the outermost oxide layer of titanium accompanied by the electrochemical apatite-deposition on its surface. (+info)
Chromium (VI) induced oxidative damage to DNA: increase of urinary 8-hydroxydeoxyguanosine concentrations (8-OHdG) among electroplating workers.
AIMS: To investigate the concentration of urinary 8-hydroxydeoxyguanosine (8-OHdG) among electroplating workers in Taiwan. METHODS: Fifty workers were selected from five chromium (Cr) electroplating plants in central Taiwan. The 20 control subjects were office workers with no previous exposure to Cr. Urinary 8-OHdG concentrations were determined using high performance liquid chromatography with electrochemical detection. RESULTS: Urinary 8-OHdG concentrations among Cr workers (1149.5 pmol/kg/day) were higher than those in the control group (730.2 pmol/kg/day). There was a positive correlation between urinary 8-OHdG concentrations and urinary Cr concentration (r = 0.447, p < 0.01), and urinary 8-OHdG correlated positively with airborne Cr concentration (r = 0.285). Using multiple regression analysis, the factors that affected urinary 8-OHdG concentrations were alcohol, the common cold, and high urinary Cr concentration. There was a high correlation of urinary 8-OHdG with both smoking and drinking, but multiple regression analysis showed that smoking was not a significant factor. Age and gender were also non-significant factors. CONCLUSION: 8-OHdG, which is an indicator of oxidative DNA damage, was a sensitive biomarker for Cr exposure. (+info)
Evaluation of the amalgamation reaction of experimental Ag-Sn-Cu alloys containing Pd using a mercury plating technique.
A mercury plating technique was used to determine the phases forming on experimental Ag-Sn-Cu alloy powders (with and without Pd) exposed to electrolytically deposited mercury. Four series of alloy powders were made: a) 1.5% Pd with 10-14% Cu (CU series); b) 1.0% Pd with 10-14% Cu (1PD series); c) 1.5% Pd with different ratios of Ag3Sn (gamma) to Ag4Sn (beta) with 12% Cu (AGSN series); and d) 9-13% Cu with no Pd (NOPD series). Each powder was pressed on a freshly prepared amalgam specimen made from the same powder and metallographically polished until cross sections appeared; mercury was electroplated on the alloy particles. Alloy powders, amalgams and electroplated specimens were examined using XRD and SEM/EDS. XRD confirmed the presence of gamma2 in amalgams made from alloys with Cu < 13% or with Ag3Sn/Ag4Sn > 0.8. Specimens with moderately plated Hg showed gamma1 (Ag2Hg3) polyhedra and eta' Cu6Sn5, but not gamma2. This method effectively identifies alloys prone to forming gamma2. (+info)
Hazardous effects of effluent from the chrome plating industry: 70 kDa heat shock protein expression as a marker of cellular damage in transgenic Drosophila melanogaster (hsp70-lacZ).
Hazardous effects of an effluent from the chrome plating industry were examined by exposing transgenic Drosophila melanogaster (hsp70-lacZ) to various concentrations (0.05, 0.1, 1.0, 10.0, and 100.0 micro L/mL) of the effluent through diet. The emergence pattern of adult flies was affected, along with impaired reproductive performance at the higher dietary concentrations of the effluent. Interestingly, the effect of the effluent was more pronounced in male than in female flies. The effect of the effluent on development of adult flies was concurrent with the expression pattern of the heat shock protein 70 gene (hsp70), both in larval tissues and in the reproductive organs of adult flies. We observed a dose- and time-dependent expression of hsp70 in third instar larvae exposed for different time intervals. Absence of hsp70 expression in larvae exposed to 0.1 micro L/mL of the effluent indicated that this is the highest nontoxic concentration for Drosophila. The stress gene assay in the reproductive organs of adult flies revealed hsp70 expression in the testis of male flies only. However, trypan blue dye exclusion tests in these tissues indicate tissue damage in the male accessory gland of adult flies, which was further confirmed by ultrastructural observations. In the present study we demonstrate the utility of transgenic Drosophila as an alternative animal model for evaluating hazardous effects of the effluent from the chrome plating industry and further reveal the cytoprotective role of hsp70 and its expression as an early marker in environmental risk assessment. (+info)
Dermal exposure to electroplating fluids and metalworking fluids in the UK.
This paper describes workplace dermal exposure measurements that were carried out by the Health and Safety Laboratory as part of the EU RISKOFDERM project. Exposure to metalworking fluids (MWFs) was measured at three sites on 25 subjects who were 'mechanically treating solid objects' as they loaded and supervised milling and boring machines and lathes. Thirty-one samples were obtained, of which 18 were exposures to neat mineral oils and 13 to water-oil mixes. All subjects wore Tyvek whole-body oversuits that were analysed in their entirety to extract the MWF. The geometric mean surface loading rate of the 31 oversuits was 62 micro g/cm(2)/h (GSD = 4.6) and of the seven pairs of sampling gloves (worn inside protective gloves) was 2900 micro g/cm(2)/h (GSD = 1.67). Exposure to electroplating fluids was measured at three sites on 27 subjects who were dipping objects into tanks of either chromic acid, nickel sulphate, copper sulphate, copper cyanide or zinc hydroxide. All subjects wore Tyvek whole-body oversuits that were surface scanned over their areas using a portable X-ray fluorescence spectrometer to detect all the metal atoms simultaneously. Contamination was assessed using the method of Dirichlet tessellation. The geometric mean surface loading rate of the 26 oversuits was 37 micro g/cm(2)/h (GSD = 3.5) and of the 25 pairs of sampling gloves (worn inside protective gloves) was 190 micro g/cm(2)/h (GSD = 2.75). Almost all of the electroplating samples were below the limit of quantification. More than one species of metal atoms was found on some of the samples afterwards, indicating cross-contamination from other baths during the sampling period. (+info)