Characterization of Tetrodes Coated with Au Nanoparticles (AuNPs) and PEDOT and Their Application to Thalamic Neural Signal Detection in vivo

Tetrodes, consisting of four twisted micro-wires can simultaneously record the number of neurons in the brain. To improve the quality of neuronal activity detection, the tetrode tips should be modified to increase the surface area and lower the impedance properties. In this study, tetrode tips were modified by the electrodeposition of Au nanoparticles (AuNPs) and dextran (Dex) doped poly (3,4-ethylenedioxythiophene) (PEDOT). The electrochemical properties were measured using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A decrease in the impedance value from 4.3 MΩ to 13 kΩ at 1 kHz was achieved by the modified tetrodes. The cathodic charge storage capacity (CSC(C)) of AuNPs-PEDOT deposited tetrodes was 4.5 mC/cm², as determined by CV measurements. The tetrodes that were electroplated with AuNPs and PEDOT exhibited an increased surface area, which reduced the tetrode impedance. In vivo recording in the ventral posterior medial (VPM) nucleus of the thalamus was performed to investigate the single-unit activity in normal rats. To evaluate the recording performance of modified tetrodes, spontaneous spike signals were recorded. The values of the L-ratio, isolation distance and signal-to-noise (SNR) confirmed that electroplating the tetrode surface with AuNPs and PEDOT improved the recording performance, and these parameters could be used to effectively quantify the spikes of each cluster.

Toxicity effects of nickel electroplating effluents treated by photoelectrooxidation in the industries of the Sinos River Basin / Avaliação do efeito tóxico de efluentes oriundos da indústria galvânica na região da Bacia do Rio dos Sinos após o tratamento pelo processo de fotoeletrooxidação

The Sinos river Basin is an industrial region with many tanneries and electroplating plants in southern Brazil. The wastewater generated by electroplating contains high loads of salts and metals that have to be treated before discharge. After conventional treatment, this study applied an advanced oxidative process to degrade organic additives in the electroplating bright nickel baths effluent. Synthetic rinsing water was submitted to physical-chemical coagulation for nickel removal. The sample was submitted to ecotoxicity tests, and the effluent was treated by photoelectrooxidation (PEO). The effects of current density and treatment time were evaluated. The concentration of total organic carbon (TOC) was 38% lower. The toxicity tests of the effluent treated using PEO revealed that the organic additives were partially degraded and the concentration that is toxic for test organisms was reduced.

A Bacia do Rio dos Sinos é uma região do Sul do Brasil que sedia um importante pólo da indústria coureiro-calçadista incluindo, desde o beneficiamento das peles, em curtumes, à fabricação dos acessórios, em indústrias metalúrgicas e de galvanoplastia. O efluente gerado por processos galvânicos contém carga elevada de sais e metais que devem ser tratados antes do descarte. Neste artigo foi avaliada a aplicação de um processo oxidativo avançado após o tratamento convencional do efluente, visando degradar os aditivos orgânicos presentes nos efluentes dos banhos de eletrodeposição de níquel brilhante. Um efluente sintético foi tratado pelo processo físico-químico de coagulação para a remoção do níquel. A amostra foi, então, submetida a testes de ecotoxicidade e, em seguida, o efluente foi tratado pelo processo de fotoeletrooxidação (FEO). A influência da densidade de corrente e o tempo de tratamento foram avaliados. Foi verificada uma redução de carbono orgânico total superior a 38%. Os ensaios de ecotoxicidade para o efluente tratado por fotoeletroxidação indicaram que a FEO degradou parcialmente os aditivos orgânicos e reduziu a concentração que provoca efeitos tóxicos para os organismos teste.

Quantitative classification-based occupational health management for electroplating enterprises in Baoan District of Shenzhen, China / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To improve the occupational health management levels in electroplating enterprises with quantitative classification measures and to provide a scientific basis for the prevention and control of occupational hazards in electroplating enterprises and the protection of workers' health.</p><p><b>METHODS</b>A quantitative classification table was created for the occupational health management in electroplating enterprises. The evaluation indicators included 6 items and 27 sub-items, with a total score of 100 points. Forty electroplating enterprises were selected and scored according to the quantitative classification table. These electroplating enterprises were classified into grades A, B, and C based on the scores.</p><p><b>RESULTS</b>Among 40 electroplating enterprises, 11 (27.5%) had scores of >85 points (grade A), 23 (57.5%) had scores of 60∼85 points (grade B), and 6 (15.0%) had scores of <60 points (grade C).</p><p><b>CONCLUSION</b>Quantitative classification management for electroplating enterprises is a valuable attempt, which is helpful for the supervision and management by the health department and provides an effective method for the self-management of enterprises.</p>

A Case of Chemical Pneumonitis with Gastrointestinal Disturbance Caused by Nitric Acid Inhalation

Nitric acid is a typical strong acid that is colorless, corrosive, and flammable. It is often used for industrial purposes, such as refining, metal cleaning, and electroplating. In Korea, some cases of chemical pneumonitis from nitric acid poisoning have been reported, but to our knowledge, there have been no reports of diarrhea caused by nitric acid poisoning. A 42-year-old man visited a nearby hospital because of continuous diarrhea, coughing, and dyspnea after inhaling nitric acid fumes at his workplace the previous day. He was transferred to our hospital and admitted to the intensive care unit. He showed tachypnea and hypoxemia in our emergency department. Initial chest radiographs showed diffuse interstitial infiltrates and ground glass opacity in both lungs. The patient showed improvements in clinical symptoms and on chest radiographs after receiving oxygen and mechanical ventilation, antibiotics, and systemic glucocorticoid therapy. After 20 days he was discharged and showed no symptoms and sequelae on his 1-year follow-up.

Wear of double crown systems: electroplated vs. casted female part

OBJECTIVES: The wear of telescopic crowns is a common problem often reducing the patient's satisfaction with the denture and resulting in a renewal of the denture. The study aims to compare the wear behavior of conical crowns using electroplated copings (group E ) with standard telescopic crowns with cast female parts (group C). MATERIAL AND METHODS: 10 conical crowns were milled for each group of a cast gold alloy. The specimen of group E had a conicity of 2º. The cast secondary crowns of group C had a 0º design. The electroplated coping was established by direct electroforming. An apparatus accomplishing 10,000 wear cycles performed the wear test. The retentive forces and the correlating distance during insertion and separation were measured. The wear test was separated in a start phase, an initial wear phase and the long term wear period. The retention force value and the force-distance integral of the first 0.33 mm of each cycle were calculated. RESULTS: The retentive forces were significantly higher for group E and the integrals were significantly lower for this group except the integral at cycle 10,000. The changes of retention force and integral did not differ significantly between both groups in all phases. The change of the integrals as well as the integral at the particular cycles showed higher interquartile distances for group C. CONCLUSIONS: Within the limitations of this study the tested conical crowns showed clinically acceptable retentive properties. The values reached a range comparable to retentive elements tested in recent literature. The values of group C showed higher ranges. The force measured for group E was significantly higher than for group C but the integrals showed an opposite tendency. The results indicate that an exclusive analysis of the force is not sufficient as the integral is not equivalent to the force although it describes the retentive property of the system in a better way than the force over a distance is described. Both systems seem to be suitable for clinical practice.

Multiple coatings can improve the bond durability of one-step self-etching adhesive to primary dentin / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate whether multiple coatings can improve the bond durability of one-step self-etching adhesive to primary dentin.</p><p><b>METHODS</b>Twelve caries-free human primary molars were randomly divided into 2 groups. In group 1, each tooth was hemisected into 2 halves. One half was assigned to the control subgroup 1, which was bonded with a commercially available one-step self-etching adhesive according to the manufacturer's instructions; the other half was assigned to experimental subgroup 1, in which the adhesive was applied three times before light curing. In group 2, one split half tooth was bonded with a commercially available one-step self-etching adhesive according to the manufacturer's instructions; for the other half, three layers of adhesive were applied with each successive layer of light curing. Specimens were stored in 0.9% NaCl containing 0.02% sodium azide at 37℃ for 18 months and then were subjected to microtensile bond strength test and the fracture mode analysis.</p><p><b>RESULTS</b>When the adhesive was applied three times before light curing, the bond strength of the experimental subgroup 1 was significantly higher than that of the control subgroup 1 (47.46∓13.91 vs. 38.12∓11.21 MPa, P<0.05). When using the technique of applying multiple layers of adhesive with each successive layer of light curing, no difference was observed in bond strength between the control subgroup and the experimental subgroup (39.40±8.87 vs. 40.87±9.33 MPa, P>0.05).</p><p><b>CONCLUSION</b>Multiple coatings can improve the bond durability of one-step self-etching adhesive to primary dentin when using the technique of light-curing after applying 3 layers of adhesive.</p>

Hexavalent chromium pollution and exposure level in electroplating workplace / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To investigate the pollution of hexavalent chromium in the electroplating workplace and screen the biomarkers of chromium exposure.</p><p><b>MATERIAL</b>Field occupational health investigation was conducted in 25 electroplating workplaces. 157 electroplating workers and 93 healthy unexposed controls were recruited. The epidemiological information was collected with face to face interview. Chromium in erythrocytes was determined by graphite furnace atomic absorption spectrophotometer.</p><p><b>RESULTS</b>The median of short-term exposure concentration of chromium in the air at electroplating workplace was 0.06 mg/m(3) (median) and ranging from 0.01 (detect limit) to 0.53 mg/m(3)). The median concentration of Cr (VI) in erythrocytes in electroplating workers was 4.41 (2.50 ∼ 5.29) µg/L, which was significantly higher than that in control subjects [1.54 (0.61 ∼ 2.98) µg/L, P < 0.01]. After stratified by potential confounding factors such as gender, age, smoking status and alcohol consumption, significant differences still existed between electroplating workers and control subjects, except for the subjects of age less than 30 years old (P = 0.11).</p><p><b>CONCLUSION</b>There was hexavalent chromium pollution in electroplating workplace. Occupational hazards prevention measures should be taken to control the chromium pollution hazards.</p>

[ frequency and antibiotic resistance of chromate tolerating microorganisms in Qom industrial wastewater]

Chromium is one of the major sources of environmental pollution and a potent occupational carcinogen. The hexavalent chromium compounds are more toxic than those of trivalent. Recent studies have suggested that reduction of Cr[VI] to its lower oxidation states and related free radical reactions play an important role in carcinogenic, genotoxic and immunotoxic effects in human and animals. This paper reports occurrence of chromium tolerant and antibiotic resistant organism of four industrial wastewaters including electroplating, textile, galvanization, and dye manufacturing in Qom. In this study 241 isolates including 23 gram positive coccus, 3 gram negative bacilli and 215 gram positive bacilli were obtained by using of LB Agar plus determined concentration of potassium chromate. A gram positive coccus, chromate reducing bacteria strain isolated from effluent of chromo plaiting could tolerate up to 760mM concentration in 34[degree]c and pH=7 within 24h and showed resistance to some antibiotics. Biochemical, physiological, morphological and 16SrRNA tests showed this bacteria belongs to staphylococcus arlettae strain R1-7A. The result indicates that the indigenous microbial isolates can be useful for hexavalent chromium detoxification of chromium contamination environment and reduction of its pathogenicity and carcinogenicity, on the other hand the control of these bacteria is important from the medical view

Aplicabilidade do PPRA: análise crítica dos riscos ocupacionais na saúde do trabalhador / Feasibility study for PPRA: review of occupational hazards in oral health in the work environment

As doenças bucais ocupacionais e os acidentes de trabalho requerem medidas de prevenção implantadas no sistema de gestão de segurança e saúde no trabalho, a fim de estabelecer um ambiente de trabalho mais seguro. No caso do ambiente de trabalho apresentado no presente estudo, equacionar prevenção de doenças bucais ocupacionais é uma tarefa árdua. A legislação vigente exige da empresa, elaborar e manter um Programa de Prevenção de Riscos Ambientais (PPRA), visando preservar e manter a segurança e saúde de seus trabalhadores, em consonância com as demais normas regulamentadoras e com os demais requisitos legais, adentrando nesta interface a Odontologia do Trabalho. Por meio do conhecimento técnico-científico da Odontologia do Trabalho, este trabalho propõe incluir nas diretrizes para elaboração e implementação de um PPRA em um processo específico de galvanoplastia os riscos químicos com potencial de inferir na saúde bucal do trabalhador. Obtendo a associação entre a identificação no PPRA dos riscos ambientais e dos possíveis agravos e comprometimento da saúde bucal do trabalhador. Concluindo ser viável a contribuição da odontologia do trabalho na elaboração do PPRA visando à prevenção da saúde bucal dos que neste ambiente laboram; sendo necessário o monitoramento do binômio ambiente laboral e saúde bucal do trabalhador, a análise dos critérios para o estabelecimento de limites de tolerância, a eficácia dos equipamentos de proteção e a descrição dos riscos à saúde bucal na ficha de informação de segurança de produto químico.

Oral diseases and occupational accidents require prevention measures to be implemented in the systems of health and safety management at the workplace for a safer work environment. In the case of the work environment presented in this study, the prevention of occupational oral diseases is a daunting task. The current Brazilian legislation requires companies to establish and enforce a program named Occupational Hazard Prevention Program (PPRA) to help keep good safety and health conditions of their workers in line with regulatory standards and other legal requirements. This paper aims to include potentially damaging chemical risks to oral health of workers in the guidelines of the PPRA program and use them in a specific electroplating process. Through technical and scientific research, this work seeks to associate PPRA identification of environmental risks and its hazards to the possible risk of compromising the oral health of workers. It concludes by proving the positive contribution of dentistry labour in PPRA especially in the prevention of oral health damage, the requirement of monitoring the binomial work environment to maintain a good oral health of workers, analysis of criteria to establish tolerance limits, studies to assess efficiency level of equipment, and description of chemical products risks to oral health to be included in the safety guideline forms.

Morbidades referidas por trabalhadoras que produzem joias folheadas em Limeira, SP / Morbidity reported by workers who produce plated jewelry in Limeira, SP, Brazil

Introdução: a cidade de Limeira (SP) se caracteriza por ser um polo de empresas do ramo de joias folheadas e bijuterias, sendo a maior parte da mão de obra composta por mulheres. Objetivo: verificar as morbidades referidas por mulheres expostas ao cianeto no setor de bijuterias e joias folheadas na cidade de Limeira em 2007. Metodologia: estudo transversal realizado com 383 trabalhadoras, comparando-se um grupo de 191 mulheres trabalhadoras em galvanoplastias consideradas qualitativamente expostas ao cianeto com um grupo de 192 mulheres não expostas ao cianeto. Foi aplicado o Índice de Capacidade para o Trabalho, o Questionário de Tolerância de Fagerstrõm e um questionário sociodemográfico e ocupacional. Resultados: O grupo considerado exposto ao cianeto apresentou: menor média de tempo de trabalho no cargo (p = 0,008), maior proporção que trabalha com produtos químicos (p < 0,001), que usa Equipamento de Proteção Individual (p < 0,001), que recebe equipamento das empresas em que trabalham (p < 0,001), menor quantidade de morbidades referidas (p = 0,042), mas maior prevalência de bronquite crônica (p = 0,027), sinusite crônica (p = 0,022) e disfunções da tireoide (p = 0,022). Conclusões: os resultados apontam para a necessidade de pesquisas de coorte que analisem a associação entre os agravos apresentados e a exposição ao cianeto.

Introduction: The city of Limeira in São Paulo, Brazil, is characterized by a cluster of companies producing jewelry, plated jewelry, and fashion jewelry, with most of the laborforce composed of women. Objective: The purpose of this research was to assess the health conditions of workers from gold plated and costume jewelry manufacturers in Limeira, in 2007. Methodology: Transversal study involving 383 women, comparing a group of 191 workers of electroplating sites considered exposed to cyanide to a group of 192 non-exposed. Work Index Capacity, Fagerstrõm Scale of Tolerance, and a socio-demographic and occupational questionnaire wereapplied. Results: The exposed group presented shorter average of time working in the company (p = 0.008), higher proportion of workers dealing with chemicals (p<0.001), wearing Personal Protective Equipment (PPE) (p <0.001), and receiving PPE provided by the companies where they worked (p <0.001). The group exposed to cyanide also presented lower proportion in reported morbidity (p = 0.042), but higher prevalence of chronic bronchitis (p = 0.027), chronic sinusitis (p = 0.022), and thyroid disorders (p = 0.022). Conclusion: The results indicate the needfor cohort studies to examine the association between the reported diseases and cyanide exposure.

A comprehensive review of techniques for biofunctionalization of titanium

A number of surface modification techniques using immobilization of biofunctional molecules of Titanium (Ti) for dental implants as well as surface properties of Ti and Ti alloys have been developed. The method using passive surface oxide film on titanium takes advantage of the fact that the surface film on Ti consists mainly of amorphous or low-crystalline and non-stoichiometric TiO2. In another method, the reconstruction of passive films, calcium phosphate naturally forms on Ti and its alloys, which is characteristic of Ti. A third method uses the surface active hydroxyl group. The oxide surface immediately reacts with water molecules and hydroxyl groups are formed. The hydroxyl groups dissociate in aqueous solutions and show acidic and basic properties. Several additional methods are also possible, including surface modification techniques, immobilization of poly(ethylene glycol), and immobilization of biomolecules such as bone morphogenetic protein, peptide, collagen, hydrogel, and gelatin.

Infraestructura de oro para prótesis metal-cerámicas obtenidas mediante técnica de electrodeposición / Infrastructure gold for metal-on-ceramic obtained by electrodeposition technique

La electrodeposición es un proceso químico por el cual se realiza una deposición galvánica de oro del 99% de pureza con el fin de obtener infraestructuras en prótesis metal-cerámicas. Las infraestructuras presentan, en promedio, un espesor de 0,2 mm y un desajuste marginal inferior la 20 µm, posibilitando la utilización de un mayor espesor de cerámica si la comparamos a técnicas convencionales. Esta técnica posibilita la disminución de la citotoxicidad, de las reacciones alérgicas y de la corrosión, determinando una mayor duración de las restauraciones. La coloración dorada del material permite al ceramista conseguir una estética más depurada, favoreciendo las tonalidades en la cerámica aplicada. Sin embargo, la necesidad de mano de obra calificada y de equipos modernos y de alto costo son factores que todavía hacen inviable la utilización de la electrodeposición de oro puro como práctica clínica habitual. El objetivo de este estudio es contribuir, a través de una revisión de la literatura, a la comparación en los siguientes factores: calidad del asentamiento marginal, durabilidad, biocompatibilidad, estética de las restauraciones cuyas estructuras hayan sido obtenidos por la técnica de electrodepoisición frente a restauraciones realizadas con técnicas metal-cerámicas convencionales y sistemas cerámicos

Electrodeposition is the galvanic deposition of 99% pure gold to obtain the framework for metal-ceramic prostheses. The framework is 0.2 mm thick, on average, with marginal maladjustment of less than 20 µm, enabling the use of greater ceramic thickness than that of conventional techniques. This new technique reduces cytotoxicity, allergic reactions and corrosion, resulting in longer restoration longevity. The golden coloration of the material allows the ceramist to develop a more evolved esthetic, favoring the tonality of the ceramic applied. However, the need for qualified labor and modern high-cost equipment are factors that hinder the use of electrodeposited pure gold in everyday clinical practice. The aim of this study is to perform a literature review to compare the quality of the marginal fit, longevity, biocompatibility, and esthetic of restorations whose copings were obtained by the electrodeposition technique using conventional metal-ceramics and ceramic systems

Aplicação da galvanoterapia em uma máquina de tatuar para tratamento de estrias / Adaptation of galvanotherapy in tattoo machine for striae treatment

As estrias que são uma atrofia de pele adquirida devido ao rompimento de fibras elásticas e colágenas. Um dos métodos de tratamento para as estrias é a galvanopuntura. Seus efeitos estão relacionados ao estímulo elétrico, baseado na compilação dos efeitos intrínsecos da corrente contínua (galvânica) que promovem uma inflamação aguda localizada, extremamente eficiente na regeneração do tecido conjuntivo rompido. Este estudo utilizou a corrente galvânica associada a uma máquina de tatuar (protótipo). Foram aplicadas sete sessões, em uma paciente, uma vez por semana, tratando três estrias, uma com galvanopuntura tradicional e as outras duas com a máquina de tatuar associada ou não a corrente. A avaliação foi realizada por meio de ficha de avaliação e biópsias antes e após as sete sessões. O objetivo foi verificar os efeitos da aplicação da corrente galvânica associada a um aparelho de tatuagem na obtenção de uma resposta inflamatória. Concluiu-se que a maior eficácia desse tratamento foi utilizando a corrente galvânica, porém, associada com a máquina de tatuar, os resultados foram superiores, obtendo maior tempo inflamatório, menor tempo para efetuar a aplicação e, sobretudo, promovendo menor dor e desconforto à paciente. Acreditamos que este protótipo seja útil na prática clínica da fisioterapia dermato-funcional.

The striae are skin atrophy due to the disruption of elastic and collagen fibers. One treatment method for the striae is the galvanopuncture. Its effect is related to electrical stimulation, that promote an acute located inflammation, without any systemic effect, but extremely efficient in the regeneration of broken tissue. This study used the galvanic current associated with a tattoo machine (prototype). It is a study with one patient, applying seven sessions once a week, treating 3 striae with a traditional galvanopuncture and other 2 striae with the tattoo machine associated or not to electric current. The evaluation was conducted through an evaluation form and biopsies before and after the seven sessions. The objective was to verify the effects of the application of galvanic current equipment associated with tattoo machine on achieving an inflammatory response. It was concluded that such treatment was more effective using the galvanic current, but with the tattoo machine associated, the results were better, gaining more inflammatory time, less time to the application and, above all, promoting minor pain and discomfort to the patient. We concluded that this prototype could be useful in clinical practice of physical therapy dermato-functional.

Electro-deposition of cerium thin film compound, elaboration and characterisation

Cerium oxide films are widely studied as a promising alternative to the toxic hexavalent Chromium Cr [VI] based pre-treatments for the corrosion protection of different metals and alloys. Cathodic electro-deposition of Cerium compound thin films was realized on Ti alloy [TA6V] substrates from a Ce [NO3]3, 6H2O in water-ethyl alcohol solutions at 0.01 M. Experimental conditions to obtain homogeneous and crack free thin films were determined. The deposited cerium quantity, as expected, is proportional to the used electric charge, following the Faraday law. Subsequent thermal treatment led to a CeO2 coating, which is expected to increase the TA6V oxidation resistance at high temperatures. The deposits were characterized by Differential Scanning Calorimetry [DSC], optical and scanning electron microscopies

Targetry for cyclotron production of no carrier-added cadmium- 109 from natAg[p, n] 109 Cd reaction

Solid targets that consist of powder and electrodeposited targets are used commonly to produce radionuclides by accelerators. Since silver is easily electrodeposited in cyanide baths and has a very excellent thermal conductivity, the electrodeposited target is preferable to produce [109] Cd. To avoid cracking of peeling of the target during bombardment, it should have a level surface and a good adhesion to substrate. Hence, suitable targetry has extraordinary importance for the interested radionuclide production. Excitation function of cadmium-109 via [nat] Ag [p,n][109] Cd reaction was investigated by using ALICE-91 code. The required thickness of the silver deposit was calculated by SRIM code. Theoretical yield was calculated by means of Simpson numerical integral method. Silver was electrodeposited on copper backing by the cyanide bath. The prepared targets were examined with morphology and thermal shock tests. The most favorable beam energy was determined as 15 MeV. The desired thickness was determined to be up to 48 micro m; the theoretical calculated yield was 2.69 micro Ci/ micro A.h. Scanning electron microscope [SEM] potomicrographs and thermal shock tests represented excellent quality of the electrodeposited target. The present study suggested a good potentiality of cadmium-109 production by induced proton on electrodeposited silver targets

Anodically deposited Mn-Mo-o electrodes by direct and pulse current as novel anode materials for hydrogen production during seawater electrolysis

Hydrogen is currently well recognized as a future fuel. Its production from seawater electrolysis using electroactive anode is presented in this study. Mn-Mo-O which is known for its efficiency as well as environmentally benign nature is used in this work. Direct and pulse electro-deposition methods were applied for preparation of the Mn-Mo-O electrode. Variation of both direct and pulse current. using sulfuric MnSO4-Na2MoO4 electrolyte solutions were the basis of the experiments. The electrodes were characterized by X-Ray Diffraction [XRD], Scanning Electron Microscopy [SEM] and electrochemical measurements. The performance of the electrodes were evaluated in 0.5M NaC1 electrolyte solution by electrolysis at 1000 Am[-2]. The findings indicated that pulse electrodeposition provide anode materials with better activity and durability as compared to direct electrodeposition method. The results are discussed in terms of structure, composition and mechanical properties of the anodes

Biosorption of Cr (VI) ions from electroplating industrial effluent using immobilized Aspergillus niger biomass.

A fungus, Aspergillus niger was chemically treated with 0.1 M H2SO4 and 0.1 N NaOH to form biosorbent and it was immobilized in calcium alginate beads. The biosorption capacity of immobilized biosorbents for Cr (VI) was found to depend on pH, contact time, biosorbent dose and initial concentration of Cr (VI). The maximum uptake of Cr (VI) was 92.5, 95.9 and 98.4 mg respectively at a pH of 1.5 and with an increase in pH up to 10.5 the metal uptake decreased gradually up to 38.75, 50.19 and 65.28 mg respectively for acid treated, untreated and base treated fungal biosorbents. Increase in biosorbent dose up to 1 g of biomass and contact time up to 60 min resulted in an increase in biosorption from 19.6, 15.6 and 26.1 mg at a biosorbent dose of 0.1 g 100 ml(-1) to 92.45, 95.7 and 98.52 mg at a biosorbent dose of 1.0 g 100 ml(-1) and then further increase in adsorbent dose and contact time did not resulted in more Cr (VI) adsorption by per unit weight of biosorbent. The value of Kad (adsorption rate constant) revealed the pseudo-first order nature of biosorption. The percentage metal uptake by the biosorbent was found to decrease upto 62.33, 52.67 and 83.5 percent respectively for acid treated, untreated and base treated fungal biosorbents at the 300 mgl(-1) Cr (VI) ion concentration. The resulted data was found to fit well in Langmuir model of adsorption isotherm with a high value of correlation coefficient. The value of Qmax, b (Langmuir constants), R(L) (separation factor) and delta G (Gibb's free energy) revealed the favourable nature of adsorption. The biosorbed metal was eluted from the biosorbent by using 0.1 M H2SO4 as elutant. Immobilized biosorbent can be reused for five consecutive biosorption/desorption cycles without apparent loss of efficiency after its reconditioning. The biosorbent was found to perform well in the electroplating industrial effluent.

Bone response to a Ca- and P-enriched titanium surface obtained by anodization

This study evaluated bone response to a Ca- and P- enriched titanium (Ti) surface treated by a multiphase anodic spark deposition coating (BSP-AK). Two mongrel dogs received bilateral implantation of 3 Ti cylinders (4.1 x 12 mm) in the humerus, being either BSP-AK treated or untreated (machined - control). At 8 weeks postimplantation, bone fragments containing the implants were harvested and processed for histologic and histomorphometric analyses. Bone formation was observed in cortical area and towards the medullary canal associated to approximately 1/3 of implant extension. In most cases, in the medullary area, collagen fiber bundles were detected adjacent and oriented parallel to Ti surfaces. Such connective tissue formation exhibited focal areas of mineralized matrix lined by active osteoblasts. The mean percentages of bone-to-implant contact were 2.3 (0.0-7.2 range) for BSP-AK and 0.4 (0.0-1.3 range) for control. Although the Mann-Whitney test did not detect statistically significant differences between groups, these results indicate a trend of BSP-AK treated surfaces to support contact osteogenesis in an experimental model that produces low bone-to-implant contact values.

O objetivo desse estudo foi avaliar a resposta do tecido ósseo à superfície de titânio (Ti) enriquecida com Ca e P obtida por anodização (BSP-AK). Três cilindros de Ti (4,1 x 12 mm) BSP-AK ou usinado (controle) foram implantados bilateralmente nos úmeros de dois cães de raça indefinida. Oito semanas após a implantação, os fragmentos ósseos contendo os implantes foram removidos e processados para análises histológica e histomorfométrica. A formação óssea foi observada na região cortical e no canal medular até aproximadamente um terço da extensão do implante. Na maioria dos casos, feixes de fibras colágenas dispostos paralelamente à superfície do implante foram observados na região medular. Nessa região observaram-se também áreas focais de formação de matriz mineralizada e osteoblastos ativos. Os implantes do grupo BSP-AK apresentaram média de contato osso-implante 2,3 por cento, com medidas variando de 0,0 a 7,2 por cento e os do grupo controle tiveram média 0,4 por cento, com medidas variando de 0,0 a 1,3 por cento. Apesar do teste de Mann-Whitney não mostrar diferença estatisticamente significante entre os grupos, nossos resultados indicaram uma tendência para a ocorrência de osteogênese de contato na superfície BSP-AK em um modelo experimental que resulta em baixos valores de contato osso-implante.

[Use of reverse osmosis for removal of chromium from electroplating industrial sewages]

Chromium is a transitional element of group 6 and is the 21rst common element in the nature which occurs in two forms: a three valent and a 6 valent form. Electroplating industry contributes much to the pollution of the environment. The aim of this study was to evaluate the efficiency of reverse osmosis membrane in the removal of chromium from industrial sewages. We also studied the optimum condition for reverse osmosis membrane for removal of chromium. At first, synthetic chromium solutions with concentrations of 5, 10, 15, 20 g/l were prepared and injected into the spiral module of 2521 TE model RO system made in Korea by CSM company. The influence of operating pressure, feed concentration, temperature, and pH on chromium removal efficiency for each concentration was determined. Our study revealed that a 200psi pressure [u=0.Ol], 10 g/l concentration [a=0.05], 25°C temperature [a=0.05] and a pH of 6-7 gave rise to the optimum condition for removal chromium. The efficiency of chromium removal by reverse osmosis membrane was about 99%. Therefore this method of chromium removal, when compared to other methods, is more suitable and effective