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PubMed2006

Sulfidation treatment of copper-containing plating sludge towards copper resource recovery.

The present study is concerned with the sulfidation treatment of copper-containing plating sludge towards copper resource recovery by flotation of copper sulfide from treated sludge. The sulfidation treatment was carried out by contacting simulated or real copper plating sludge with Na(2)S solution for a period of 5 min to 24 h. The initial molar ratio of S(2-) to Cu(2+) (S(2-) to Me(2+) in the case of real sludge) was adjusted to 1.00, 1.25 or 1.50, while the solid to liquid ratio was set at 1:50. As a result, it was found that copper compounds were converted to various copper sulfides within the first 5 min. In the case of simulated copper sludge, CuS was identified as the main sulfidation product at the molar ratio of S(2-) to Cu(2+) of 1.00, while Cu(7)S(4) (Roxbyite) was mainly found at the molar ratios of S(2-) to Cu(2+) of 1.50 and 1.25. Based on the measurements of oxidation-reduction potential, the formation of either CuS or Cu(7)S(4) at different S(2-) to Cu(2+) molar ratios was attributed to the changes in the oxidation-reduction potential. By contrast, in the case of sulfidation treatment of real copper sludge, CuS was predominantly formed, irrespective of S(2-) to Me(2+) molar ratio.

Copper↗
PubMed2004

Over-pulsing degrades activated iridium oxide films used for intracortical neural stimulation.

Microelectrodes using activated iridium oxide (AIROF) charge-injection coatings have been pulsed in cat cortex at levels from near-threshold for neural excitation to the reported in vitro electrochemical charge-injection limits of AIROF. The microelectrodes were subjected to continuous biphasic current pulsing, using an 0.4V (versus Ag|AgCl) anodic bias with equal cathodal and anodal pulse widths, for periods up to 7h at a frequency of either 50Hz or 100Hz. At charge densities of 3mC/cm(2), histology revealed iridium-containing deposits in tissue adjacent to the charge-injection sites and scanning electron microscopy of explanted electrodes revealed a thickened and poorly adherent AIROF coating. Microelectrodes pulsed at 2mC/cm(2) or less remained intact, with no histologic evidence of non-biologic deposits in the tissue. AIROF microelectrodes challenged in vitro under the same pulsing conditions responded similarly, with electrodes pulsed at 3mC/cm(2) showing evidence of AIROF delamination after only 100s of pulsing at 100Hz (10,000 pulses total), while electrodes pulsed at 2mC/cm(2) for 7h at 50Hz (1.3 x 10(6) pulses total) showed no evidence of damage. In vitro electrochemical potential transient measurements in buffered physiologic saline indicate that polarizing the AIROF beyond the potential window for electrolysis of water (-0.6 to 0.8V versus Ag|AgCl) results in the observed degradation.

Animals↗
PubMed2005

An investigation of the effects of hydroxyapatite coatings on the fixation strength of cortical screws.

Hydroxyapatite (HA) are commonly applied to orthopaedic implants for acceleration of osteointegration and so overcoming the loosening problems such as in cortical screws. Electrophoretic deposition (EPD) of hydroxyapatite was applied for coating of cortical screws in this work. The effects of hydroxyapatite-coated and uncoated cortical screws on insertion and extraction torque were investigated through in vivo experiments. Three groups of screws were undertaken: first group with no coating, second group coated with HA and the third group coated with HA+interlayer, a synthetic calcium silicate compound. Five sheep were operated, and 60 cortical (20 x 3) screws from those of groups were implanted in cortical femurs to observe the effect of HA and interlayer on screws. Results show that as an alternative to plasma spray coating method, the EPD process enables to produce a quick, easy, cheap and uniform adjustable coating layer. Also from biomechanical and SEM examinations, HA coating by EPD method of cortical screws resulted in extremely improved fixation with reduced risk of loosening problem.

Animals↗
PubMed2007

In vitro and in vivo performance of a novel surface treatment to enhance osseointegration of endosseous implants.

OBJECTIVE: This article shows the in vitro and in vivo characterization of a new biomimetic treatment developed to enhance the osseointegration of titanium dental implants. STUDY DESIGN: A novel biomimetic treatment of titanium was developed. Its physicochemical properties and biologic and in vivo performance were considered and studied. Mineralization capability was assessed by soaking test in simulated body fluid solution, and cytocompatibility was assessed using osteoblast-like MG63 cell culture. Histomorphometric analysis was performed at 3 time points using a sheep animal model. RESULTS: In vitro tests confirmed the biomimetic potential of the considered novel treatment. Histomorphometric analysis indicated its potential for rapid and good-quality osseointegration. CONCLUSION: The in vitro and in vivo test results indicated that the proposed novel treatment possesses a significant potential to increase the rate of osteointegration of titanium for endosseous dental implants.

Analysis of Variance↗
PubMed2006

Towards a "crippled-mode" operation of an industrial wastewater treatment plant.

In house treatment of metal plating wastewater mainly involves chemical treatments performed in continuous flow stirred tank reactors (CFSTR). The inflow of these tanks is directly produced by the plating shops activity, and the storage capacity never exceeds a few hours of incoming flow. Thus, any fault on one of the CFSTR may impose a complete stop of the whole manufacturing process, which is unacceptable for the manufacturer. Another solution would be having "spare" CFSTRs ready to be used as alternative in case of any CFSTR fault or maintenance. The latter solution however implies additional costs in equipment, storage space and maintenance so as to keep this equipment fit and ready for operation. The paper presents the study of a "crippled-mode" wastewater treatment (WWT) operation which enables a sufficiently efficient working of the WWT plant during maintenance phases and failure repairing on any of the CFSTR, without any extra equipment needed. This survey has been performed on real industrial WWT plants, with a continuous influent and under industrial operation constraints. The performances of the detoxication have been analysed when a CFSTR is short-circuited and the corresponding chemical treatment is shunt in the upstream or downstream CSFTR. This work shows the possibility of satisfying the environmental regulations with a WWT plant functioning under subnormal conditions.

Electroplating↗
PubMed1993

Video technology.

Explore the source record for details and available documents.

Electroplating↗
PubMed1997

Exposure to soluble nickel in electrolytic nickel refining.

Past and present exposure to nickel was studied in an electrolytic nickel refinery, where an increased incidence of nasal cancer had been reported, using nickel analyses in air, blood and urine. Genotoxic effects were studied using analysis of micronuclei from acridine orange-stained smears from the buccal mucosa of the workers. Workers used respirators or masks in tasks where the exposure was expected to be high. Inside the mask, nickel concentrations were 0.9-2.4 micrograms m-3 in such tasks. In those tasks where masks were not used, nickel concentrations in the breathing zone were 1.3-21 micrograms m-3. Air-borne nickel concentrations (stationary sampling) varied between 230 and 800 micrograms m-3 in 1966-1988 with no systematic change; thereafter lower concentrations (170-460 micrograms m-3) have been observed. After-shift urinary concentrations of nickel were 0.1-2 mumol l-1; they showed no correlation with nickel concentrations in the air. Concentrations of nickel in the urine were still elevated after a 2-4 week vacation. The frequency of micronucleated epithelial cells in the buccal mucosa of nickel refinery workers was not significantly elevated by comparison with referents. No relationship was observed between micronucleus frequencies and levels of nickel in air, urine or blood.

Air Pollutants, Occupational↗
PubMed1997

Occupational exposure to nickel salts in electrolytic plating.

An occupational hygiene survey was made in 38 nickel plating shops in Finland and exposure to nickel was studied by means of biological measurements and, in three shops, by using air measurements. The average after-shift urinary nickel concentration of 163 workers was 0.16 mumol l.-1 (range 0.001-4.99 mumol l.-1). After the 1-5 week vacation the urinary nickel concentration was higher than the upper reference limit of non-exposed Finns indicating that a part of water-soluble nickel salts is accumulated in the body. Urinary nickel concentrations in the shops considered clean in the industrial hygiene walk-through were not different from those observed in the shops considered dirty. The correlation between the concentrations of nickel in the air and in the urine was low, and the amount of nickel excreted in the urine exceeded the calculated inhaled amounts, indicating exposure by other routes such as ingestion.

Adult↗
PubMed2003

An in vitro comparison of tensile bond strengths of noble and base metal alloys to enamel.

STATEMENT OF PURPOSE: Many different surface treatments have been used to increase the bond strength of noble and base metal alloys to enamel, but only a few have been studied. PURPOSE: The purpose of this in vitro study was to compare the tensile bond strength of a tin-plated noble alloy, an Alloy Primer-treated noble alloy, and an airborne particle-abraded base metal alloy, all bonded to enamel with a phosphate-methacrylate resin luting agent. MATERIAL AND METHODS: Seventy noncarious molar teeth were extracted, cleaned, and embedded in autopolymerizing acrylic resin with the buccal surface of the teeth exposed. Seventy wax patterns (4-mm diameter x 2-mm thickness) were waxed, invested, and cast-50 with a noble alloy (Argedent 52) and 20 with a base metal alloy (Argeloy N.P.). Twenty of the noble alloy specimens were tin-plated (TP), 20 noble alloy specimens were treated with Alloy Primer (AP), and 20 base metal alloy specimens were airborne particle abraded (AA). All specimens were luted with a phosphate-methacrylate resin luting agent (Panavia F) and stored in 100% humidity at 37 degrees C, half for 24 hours and half for 7 days. Ten noble alloy specimens were tin-plated and stored in water for 48 hours (aged) before cementation and then stored in water for 24 hours after cementation. These specimens were used to test whether there is an advantage to aging the tin-plated surface in water before cementation. All specimens were thermocycled (5 degrees to 55 degrees C) for 500 cycles and then tested for tensile bond strength (TBS), measured in MPa, with a universal testing machine at a crosshead speed of 0.5mm/min. Various castings (n=6 per test group) were randomly selected from each group and inspected under a scanning electronic microscope to determine mode of failure. The mean values and standard deviations of all specimens were calculated for each group. A 2-way analysis of variance (ANOVA) was performed, and multiple pairwise comparisons were then completed with post hoc Tukey test (alpha=.05). RESULTS: The TBS of the tin-plated noble alloy specimens bonded to enamel (24 hours: 9.33 +/- 1.31 MPa; 7 days: 11.65 +/- 1.55 MPa) was significantly greater than the Alloy Primer noble alloy specimens (24 hours: 6.11 +/- 1.01 MPa; 7 days: 5.45 +/- 1.22 MPa) (P <.001). The Alloy Primer noble alloy group showed the lowest TBS compared with the tin-plated noble alloy and airborne particle-abraded base metal alloy group (24 hours: 10.61 +/- 1.41 MPa; 7 days: 6.94 +/- 1.40 MPa). The tin-plated noble alloy specimens showed greater TBS after storage for 7 days in distilled water compared with storage for 24 hours (24 hours: 9.33 +/- 1.31 MPa; 7 days: 11.65 +/- 1.55 MPa). Aging the tin-plated noble alloy for 48 hours in 37 degrees C (9.17 +/- 1.68 MPa) prior to cementation did not increase the TBS to enamel. The airborne particle-abraded base metal alloy showed significantly lower TBS at the 7-day storage time compared to the 24-hour storage time (24 hours: 10.61 +/- 1.41 MPa; 7 days: 6.94 +/- 1.40 MPa) (P <.001). SEM examination of the debonded metal and enamel surfaces showed mixed (adhesive and cohesive) failures for all groups. CONCLUSION: Tin-plating a noble alloy produced the highest bond strength to enamel. Storing the tin-plated noble alloy in 37 degrees C distilled water for 48 hours before cementation did not result in a change in TBS. Using an Alloy Primer with a noble alloy resulted in statistically significant lower TBS than tin-plating.

Analysis of Variance↗
PubMed1996

The effect of metal surface treatment on the shear bond strengths of base and noble metals bonded to enamel.

Adhesive resin luting agents provide a way for bonding metal surfaces to teeth through a combination of micromechanical retention to the rough metal surface and chemical adherence to metal oxides. The purpose of this study was to measure the effect of metal alloy surface treatments that would produce different textures and oxide layers on the shear bond strength of three alloys luted to etched enamel with one adhesive resin luting agent (Panavia). After a simulated porcelain firing sequence, high noble (Olympia), noble (Jelstar), and base metal (Rexillium III) alloy specimens were subjected to one of the following treatments: (1) sandblasting and simulated glazing, (2) simulated glazing only, (3) simulated glazing and sandblasting, or (4) simulated glazing, sandblasting, and tin plating. The specimens were bonded to extracted teeth and subjected to shear testing after water storage for 2 weeks, thermocycling for 500 cycles, and water storage for an additional 2 weeks. Data were analyzed with a two-way analysis of variance (alpha = 0.05). The base metal specimens and the tin-plated high noble and noble metal specimen groups exhibited similar mean shear bond strengths that were greater than the other groups. Those high noble and noble metal alloys sandblasted after simulated porcelain firing cycles and before the simulated glaze cycle exhibited nonsignificant increases in shear bond strengths compared with the groups that were either sandblasted after the simulated glaze cycle or not sandblasted at all.

Analysis of Variance↗
PubMed1997

Bond strengths of resin-to-metal bonding systems.

STATEMENT OF PROBLEM: Resinous materials for the veneers of fixed prostheses commonly require mechanical retention on metal substructures because there is no chemical adhesion. However, mechanical retention does not restrict creation of a marginal gap at the resin-metal interface, which can cause discoloration or detachment of resinous material. The development of a chemical resin-to-metal bonding could resolve this problem and also reduce the need for mechanical retention (pearls, wires) on metal frameworks. PURPOSE: This study evaluated six current methods with the use of various storage conditions to predict clinical efficacy. MATERIAL AND METHODS: Six resin-to-metal bonding systems were tested: Silicoater, Silicoater MD, Rocatec, OVS, Sebond, and Spectra-Link. All specimens were examined in bending tests after 24 hours of dry storage (category A), after 24 hours of water storage and thermocycling (category B), and after 2 months of water storage and thermocycling (category C). Tensional tests were completed for all bonding systems after dry storage, and microscopic examination (optical and SEM) was performed for all specimens. RESULTS AND CONCLUSIONS: This study indicated that certain systems can provide stable bonding of resin to metal substructures despite prolonged wet storage and intensive thermocycling. These systems can also be used clinically without retentive configurations on metal frameworks, resulting in better esthetics. Some bonding systems revealed progressive weakening of bond strengths, so research is needed to verify their clinical efficacy.

Dental Alloys↗
PubMed1997

Electroforming technology for galvanoceramic restorations.

The ceramist needs a maximum thickness of porcelain to "move light" and create the illusion of natural teeth. Galvanoceramic restorations may be used as an alternative to all ceramic restorations or ceramic restorations with cast metal substructure. Electroforming technology is used with remarkable accuracy to create a thin, yellow-gold substructure of uniform thickness. The galvanic process involves the electrolytic deposition of gold ions on a specially prepared die. Advantages of this method include a thin, warm substrate for improved esthetics, marginal integrity of 15 to 20 microns, and a simplified, economical procedure for fabricating substructures. This article describes both clinical and laboratory steps for creating galvanoceramic restoration.

Ceramics↗
PubMed1998

A simple method of increasing the adhesion between resinous cements and tinplated gold alloys: a pilot study.

PURPOSE: This study: (1) tested 2 BIS-GMA resinous cements on tinplated gold alloy surfaces with shearing forces to record their bond strengths, and (2) determined whether storage of the tinplated surfaces in water before cementation affected initial bond strengths. MATERIAL AND METHODS: The bond strengths of Panavia Ex and Panavia 21 resinous cements to tinplated Type III gold alloy were measured when subjected to shearing forces. Specimens were luted in pairs with these cements. In one group, the cementation was performed after tinplating procedures. In the other group, tinplated alloy surfaces were first stored in water at 37 degrees C for 48 hours before cementation. RESULTS: A 3-fold increase in bond strength values was recorded for tinplated specimens stored in water before cementation with both cements, these differences were statistically significant. Storage of the specimen in water before cementation appeared to increase resistance of the alloy resin bond to failure with application of shearing forces. CONCLUSION: This pilot study suggested that it would be advantageous to age tinplated gold alloy surfaces in water for 48 hours before cementation.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2003

A dual membrane UF/RO process for reclamation of spent rinses from a nickel-plating operation--a case study.

The objective of this work was to conduct treatability studies on rinse wastewater from process lines of a typical nickel-plating plant for reuse. The study comprised of three steps: (1) a plant process review and the treatability of different combinations of simulated spent rinses in the laboratory; (2) a variability monitoring of a combined rinse at the plant and a treatability study on a combined rinse in the laboratory; (3) a pilot study for reclamation of the combined rinse on site. The study established an optimum dual membrane ultrafiltration (UF)/reverse osmosis (RO) process for treating a combined liquor of spent alkaline, acidic and nickel-plating rinses which resulted in a treated water of a quality suitable for reuse as substitute for town water for the purpose of rinsing. The results of this study provided a good guide to the selection of a UF pretreatment combined with an RO membrane unit as the treatment system. The pilot plant had successfully operated for 6 months, consistently producing a high quality product water (< 95 microS cm-1) at an overall water recovery of 67.5%. The quality of reclaimed water was better than town water used at the factory. The product water from the pilot plant has been used as substitute of town water for in-process rinsing at the factory with no detrimental effects for 3 months.

Conservation of Natural Resources↗
PubMed2003

Biocompatibility and charge injection property of iridium film formed by ion beam assisted deposition.

Iridium thin film formed by electron-beam evaporation with simultaneous bombardment of Ar ion beam was evaluated for a stimulating neural electrode. The electrochemical behavior of as-deposited Ir film on Ni-Ti sample was almost identical to bulk Ir by producing much higher open-circuit corrosion potential and much lower anodic current density than the uncoated Ni-Ti in both 1N sulfuric acid and saline solution. The charge injection capability of Ir film was compared with that of Pt electrode currently used mostly as a stimulating neural electrode. The charge density of Pt was small and unchanged with increasing number of activating cycles in 0.1M H(2)SO(4), whilst the Ir film continuously produced increases in charge density. The charge injection density of Ir film in physiological solution was higher for the more activated sample under the identical stimulating condition. Attachment and proliferation with PC12 cells on Ir-coated CP Ti without applying electrical stimulation was similar to the polished CP Ti. A network of neurons and extending axons were formed on Ir film.

Animals↗
PubMed2001

Plutonium contamination from accidental release or simply fallout: study of soils at Palomares (Spain).

The activity concentration of plutonium in an environmental sample does not usually constitute sufficient information to determine if it is due only to fallout. Alpha and gamma spectrometry are used here conjointly in the study of environmental soil samples to distinguish between samples showing plutonium contamination due to fallout exclusively, and samples contaminated with plutonium from another source. The method was applied to soil samples collected in Palomares (Spain), where an accidental release of aerosols contaminated with plutonium occurred. The two contributions (fallout and accidentally released plutonium) were separated by means of the activity ratios between various radionuclides present in the samples analyzed. The fallout level was estimated from the 239 + 240Pu/137Cs activity ratio. For samples showing contamination due to the accident, the 238Pu/239 + 240Pu and 239Pu/240Pu activity ratios were also calculated to determine the grade of plutonium of this contamination.

Americium↗