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.
Animals ; Brain ; Dextrans ; Dielectric Spectroscopy ; Electric Impedance ; Electrodes ; Electroplating ; Microelectrodes ; Nanoparticles* ; Neurons ; Rats ; Thalamus

OBJECTIVETo 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.

METHODSA 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.

RESULTSAmong 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).

CONCLUSIONQuantitative 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.

Electroplating ; Humans ; Occupational Exposure ; Occupational Health

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.
Anoxia ; Anti-Bacterial Agents ; Cough ; Diarrhea ; Dyspnea ; Electroplating ; Emergencies ; Follow-Up Studies ; Glass ; Humans ; Inhalation ; Intensive Care Units ; Korea ; Lung ; Nitric Acid ; Oxygen ; Pneumonia ; Respiration, Artificial ; Tachypnea ; Thorax

OBJECTIVETo investigate whether multiple coatings can improve the bond durability of one-step self-etching adhesive to primary dentin.

METHODSTwelve 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.

RESULTSWhen 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).

CONCLUSIONMultiple 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.

Acid Etching, Dental ; methods ; Adhesiveness ; Child ; Coated Materials, Biocompatible ; chemical synthesis ; chemistry ; pharmacology ; Dental Cements ; chemical synthesis ; chemistry ; pharmacology ; Dental Prosthesis ; Dental Restoration Failure ; Dentin ; chemistry ; drug effects ; Dentin-Bonding Agents ; pharmacology ; Electroplating ; methods ; Equipment Failure Analysis ; Humans ; Materials Testing ; Tensile Strength ; drug effects

OBJECTIVETo investigate the pollution of hexavalent chromium in the electroplating workplace and screen the biomarkers of chromium exposure.

MATERIALField 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.

RESULTSThe 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).

CONCLUSIONThere was hexavalent chromium pollution in electroplating workplace. Occupational hazards prevention measures should be taken to control the chromium pollution hazards.

Adult ; Air Pollutants, Occupational ; analysis ; Chromium ; blood ; Electroplating ; Environmental Monitoring ; Erythrocytes ; chemistry ; Female ; Humans ; Male ; Middle Aged ; Occupational Exposure ; analysis ; Workplace ; Young Adult

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.
Alloys ; Bone Morphogenetic Proteins ; Calcium ; Calcium Phosphates ; Collagen ; Dental Implants ; Electroplating ; Gelatin ; Hydrogel ; Imidazoles ; Immobilization ; Nitro Compounds ; Surface Properties ; Titanium

Adult ; Chromium ; adverse effects ; Electroplating ; Female ; Humans ; Male ; Middle Aged ; Nose ; drug effects ; Occupational Exposure ; adverse effects

The purpose of this study was to evaluate electroless plating as a method of increasing the diameter of an orthodontic wire in comparison with eletroplating. After pretreatment plating of the 0.016 inch stainless steel orthodontic wire, electroless plating was performed at 90 degrees C until the diameter of the wire was increased to 0.018 inch. During the process of electroless plating, the diameter of the wire was measured every 5 minutes to examine the increasing ratio of the wire' diameter per time unit. And to examine the uniformity, the diameter at 3 points on the electroless-plated orthodontic wire was measured. An X-ray diffraction test for analyzing the nature of the plated metal and a 3-point bending test for analyzing the physical property were performed. The electroless-plated wire group showed a increased tendency for stiffness, yield strength, and ultimate strength than the electroplated wire group. And there was a statistically significant difference between the two groups for stiffness and ultimate strength. In the electroless-plated wire group, the increasing ratio of the diameter was 0.00461 +/-.00003 mm/5 min (0.00092 mm/min). In the electroplated wire group, it was 0.00821 +/-.00015 mm/min. The results of the uniformity test showed a tendency for uniformity in both the plating methods. The results of this study suggest that electroless plating of the wire is closer to the ready-made wire than electroplating wire in terms of the physical property. However, the length of plating time needs further consideration for the clinical application of electroless plating.
Electroplating* ; Orthodontic Wires* ; Stainless Steel ; X-Ray Diffraction

Nitric acid is an oxidizing agent used in metal refining and cleaning, electroplating, and other industrial applications. Its accidental spillage generates oxides of nitrogen, including nitric oxide (NO) and nitrogen dioxide (NO2), which cause chemical pneumonitis when inhaled. The clinical presentation of a nitric acid inhalation injury depends on the duration and intensity of exposure. In mild cases, there may be no symptoms during the first few hours after exposure, or the typical symptoms of pulmonary edema can appear within 3-24 hours. However, in cases of prolonged exposure, progressive pulmonary edema develops instantaneously and patients may not survive for more than 24 hours. We report a case of a 44-year-old male who was presented with acute respiratory distress syndrome after nitric acid inhalation. He complained of cough and dyspnea of a sudden onset after inhaling nitric acid fumes at his workplace over a four-hour period. He required endotracheal intubation and mechanical ventilation due to fulminant respiratory failure. He was managed successfully with mechanical ventilation using positive end expiratory pressure and systemic corticosteroids, and recovered fully without any deterioration in his pulmonary function.
Adrenal Cortex Hormones ; Adult ; Cough ; Dyspnea ; Electroplating ; Humans ; Inhalation* ; Intubation, Intratracheal ; Male ; Nitric Acid* ; Nitric Oxide ; Nitrogen ; Nitrogen Dioxide ; Oxides ; Pneumonia ; Positive-Pressure Respiration ; Pulmonary Edema ; Respiration, Artificial ; Respiratory Distress Syndrome, Adult* ; Respiratory Insufficiency

The purpose of this study was to examine the cytotoxicity of orthodontic wire which had an increased diameter through electroplating, and to evaluate its possible clinical applications. First, nickel plating was carried out on the commercially available stainless steel wire using an electroplating technique. For the comparison of the electroplated wire with ready made stainless steel wire and titanium or copper, each wire was incubated for 72 hours in a medium. The release of the metal ion was measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrophotometer). Balb/c 3T3 mouse fibroblast was put on a microplate and placed in an incubated medium of 75%, 50%, and 20% dilation. An MTT analysis was used to compare with the medium only. The change in absorbency value of each wire group and the difference of absorbency value according to the change of dilution was measured. The results of ICP-AES analysis showed that great amount nickel ion was isolated from electroplated orthodontic wires and great amount copper ion was isolated from copper. The results of the MTT analysis showed that there was no difference in the absorbency value of titanium at any dilution. However, the electroplated wires (p < 0.001), the stainless steel wires (p < 0.05) and the copper (p < 0.001) were statistically significantly lower than those of medium only at all dilutions. Assessment as per ISO 10993, part 5, showed that electroplated wire was alloted to "moderate cytotoxic", the titanium and stainless steel wire were "non-cytotoxic". The results of this study indicate that the electroplated orthodontic wires need additional efforts to decrease cytotoxicity for their clinical applications.
Animals ; Copper ; Electroplating ; Fibroblasts ; Mice ; Nickel ; Orthodontic Wires* ; Plasma ; Stainless Steel* ; Titanium