OBJECTIVETo establish a method for determination of a variety of acid gas in the workplace air by Ion Chromatography. (hydrofluoric acid, hydrogen chloride or hydrochloric acid, sulfur anhydride or sulfuric acid, phosphoric acid, oxalic acid).

METHODThe sample in workplace air was collected by the porous glass plate absorption tube containing 5 ml leacheate. (Sulfuric acid fog, phosphoric acid aerosol microporous membrane after collection, eluted with 5 ml of eluent.) To separated by AS14+AG14 chromatography column, by carbonate (2.0+1.0) mmol/L (Na(2)CO(3)-NaHCO(3)) as eluent, flow rate of 1 ml/min, then analyzed by electrical conductivity detector. The retain time was used for qualitative and the peak area was used for quantitation.

RESULTSThe each ion of a variety of acid gas in the air of workplace were excellent in carbonate eluent separation. The linear range of working curve of 0∼20 mg/L. The correlation coefficient r>0.999; lower detection limit of 3.6∼115 µg/L; quantitative limit of 0.012∼0.53 mg/L; acquisition of 15L air were measured, the minimum detection concentration is 0.004 0∼0.13 mg/m(3). The recovery rate is 99.7%∼101.1%. In the sample without mutual interference ions. Samples stored at room temperature for 7 days.

CONCLUSIONThe same analysis method, the detection of various acidic gases in the air of workplace, simple operation, good separation effect, high sensitivity, high detection efficiency, easy popularization and application.

Acids, Noncarboxylic ; analysis ; Air ; analysis ; Air Pollutants, Occupational ; analysis ; Chromatography ; methods ; Gases ; Hydrochloric Acid ; Hydrofluoric Acid ; Ions ; analysis ; Limit of Detection ; Phosphoric Acids ; Sulfuric Acids ; Workplace

This study was performed to evaluate the interfacial shear bond strength of base (direct and indirect) and repair composites with aging and surface treatment methods. Direct composite resin specimens (Charisma(R), Heraeus Kulzer, Germany) were aged for 5 min, 1 hour, 24 hours, and 1 week in 37degrees C distilled water before surface treatment, and then divided into five groups: Group 1, grinding; Group 2, grinding and application of bonding agent; Group 3, grinding, etching with 37% phosphoric acid for 30sec, and application of bonding agent; Group 4, grinding, etching with 37% phosphoric acid for 30sec, silane treatment, and application of bonding agent; Group 5, grinding, etching with 4% hydrofluoric acid for 30sec, silane treatment, and application of bonding agent. Indirect composite resin specimens (Artglass(R), Heraeus Kulzer, Germany) were aged for 1 week in 37degrees C distilled water and divided into seven groups: Group 1 - Group 5, equal to Charisma specimens; Group 6, grinding, etching with 37% phosphoric acid for 60sec, silane treatment, and application of bonding agent; Group7, grinding, etching with 4% hydrofluoric acid for 60 sec, silane treatment, and application of bonding agent. The repair material(Charisma(R)) was then added on the center of the surface (5 mm in diameter, 5 mm in height). The shear bond strength was tested and the data was analyzed using one-way ANOVA and the Student-Newman-Keuls test. The following conclusions were drawn. 1. The shear bond strength of Charisma(R) specimens aged for 1 hour was significantly higher in Group 2 and Group 5 than in Group 1 (p<0.05), and that of Charisma(R) specimens aged for 1 week was significantly higher in Group 3 and Group 5 than in Group 1 (p<0.05). No significant difference was found in the bond strength of specimens aged for 5 min and 24 hours. 2. In Group 2 of the Charisma(R) specimens, there was significant difference between the bond strength of 24 hours and that of 1 week (p<0.05). 3. In Group 4 of the Charisma(R) specimens, the shear bond strength of specimens aged for 24 hours was significantly higher than the others(p<0.05). 4. There was no significant difference between the shear bond strength of the Artglass(R) specimens. 5. Most of the Charisma(R) specimens showed cohesive fractures. Artglass(R) specimens that were etched with acid (phosphoric or hydrofluoric) for 30 sec showed more cohesive fractures.
Aged ; Aging ; Humans ; Hydrofluoric Acid ; Phosphoric Acids ; Water

OBJECTIVES: This study was designed to evaluate exposure levels of various chemicals used in wafer fabrication product lines in the semiconductor industry where work-related leukemia has occurred. METHODS: The research focused on 9 representative wafer fabrication bays among a total of 25 bays in a semiconductor product line. We monitored the chemical substances categorized as human carcinogens with respect to leukemia as well as harmful chemicals used in the bays and substances with hematologic and reproductive toxicities to evaluate the overall health effect for semiconductor industry workers. With respect to monitoring, active and passive sampling techniques were introduced. Eight-hour long-term and 15-minute short-term sampling was conducted for the area as well as on personal samples. RESULTS: The results of the measurements for each substance showed that benzene, toluene, xylene, n-butyl acetate, 2-methoxyethanol, 2-heptanone, ethylene glycol, sulfuric acid, and phosphoric acid were non-detectable (ND) in all samples. Arsine was either "ND" or it existed only in trace form in the bay air. The maximum exposure concentration of fluorides was approximately 0.17% of the Korea occupational exposure limits, with hydrofluoric acid at about 0.2%, hydrochloric acid 0.06%, nitric acid 0.05%, isopropyl alcohol 0.4%, and phosphine at about 2%. The maximum exposure concentration of propylene glycol monomethyl ether acetate (PGMEA) was 0.0870 ppm, representing only 0.1% or less than the American Industrial Hygiene Association recommended standard (100 ppm). CONCLUSION: Benzene, a known human carcinogen for leukemia, and arsine, a hematologic toxin, were not detected in wafer fabrication sites in this study. Among reproductive toxic substances, n-butyl acetate was not detected, but fluorides and PGMEA existed in small amounts in the air. This investigation was focused on the air-borne chemical concentrations only in regular working conditions. Unconditional exposures during spills and/or maintenance tasks and by-product chemicals were not included. Supplementary studies might be required.
2-Propanol ; Arsenicals ; Bays ; Benzene ; Carcinogens ; Ether, Ethyl ; Ethylene Glycol ; Ethylene Glycols ; Ethylenes ; Fluorides ; Humans ; Hydrochloric Acid ; Hydrofluoric Acid ; Ketones ; Korea ; Leukemia ; Nitric Acid ; Occupational Exposure ; Occupational Health ; Phosphines ; Phosphoric Acids ; Propylene Glycol ; Propylene Glycols ; Semiconductors ; Sulfur ; Sulfuric Acids ; Toluene ; Xylenes

OBJECTIVE: The purpose of this study was to investigate the effect of using laser for ceramic bracket bonding of porcelain surfaces and to compare it with conventional treatment of porcelain surfaces. METHODS: Ninety feldspathic porcelain specimens were divided into 9 groups of 10, with each group having different surface treatments performed. Surface treatment groups were orthophosphoric acid, orthophosphoric acid with silane, hydrofluoric acid, hydrofluoric acid with silane, sandblasted, sandblasted with silane, laser etched, laser etched with silane, and glazed surface served as a control group. In the laser etched groups, the specimens were irradiated with 2-watt superpulse carbon dioxide (CO2) laser for 20 seconds. Ceramic brackets were bonded with light-cure composite resin and all specimens were stored in water at 37degrees C for 24 hours. Shear bond strength was determined in megapascals (MPa) by shear test at 1 mm/minute crosshead speed and the failure pattern was assessed. For statistical analysis, one-way ANOVA and tukey test were used. RESULTS: Statistical analysis showed significant differences between the groups. The HFA + S group showed the highest mean shear bond strength (13.92 +/- 1.94 MPa). This was followed by SB + S (10.16 +/- 1.27 MPa), HFA (10.09 +/- 1.07 MPa), L + S (8.25 +/- 1.24 MPa), L (7.86 +/- 0.96 MPa), OFS + S (7.22 +/- 1.09 MPa), SB (3.41 +/- 0.37 MPa), OFA (2.81 +/- 0.37 MPa), G (2,46 +/- 1.36 MPa). Bond failure patterns of HFA and silane groups, except L + S, were cohesive modes in porcelain while adhesive failure was observed in the control group and the rest of the groups. Conclusions : A 2-watt superpulse CO2 laser etching of porcelain surfaces can provide a satisfactory result for porcelain surface treatment for ceramic bracket bonding. Laser irradiation may be an alternative conditioning method for the treatment of porcelain surfaces.
Adhesives ; Carbon Dioxide ; Ceramics ; Dental Porcelain ; Hydrofluoric Acid ; Lasers, Gas ; Phosphoric Acids ; Water

acid and phosphoric acid, 24 (group 2 GC) were prepared at galvanostatic mode in calcium glycerophosphate and calcium acetate and 24 (group 3 CMP (Calcium Metaphosphate) Coating were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid followed by CMP coating. Rest of 24 (control group were as a control group of RBM surface. Bone tissue responses were evaluated by resonance frequency analysis (RFA) that were undertaken at 2, 4 and 6 weeks after implant placement in the mandible of mini-pig. Group 1 SP (anodized with sulfuric acid and phosphoric acid implants) demonstrated slightly stronger bone responses than control Group RBM. Group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) demonstrated no difference which were compared with control group. Group 3 GMP (anodized and CMP coated implants) demonstrated slightly stronger and faster bone responses than any other implants. But, all observation result of RFA showed no significant differences between experimental groups with various surface type. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact for group 2 GC. Significantly more bone formation was found inside threaded area for group 2 GC. It was concluded that group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) showed more effects on the bone tissue responses than RBM surface in initial period of implantation. In addition, CMP showed a tendency to promote bone tissue responses.]]>
Acetates ; Bone and Bones ; Calcium ; Calcium Compounds ; Glycerophosphates ; Mandible ; Osseointegration ; Osteogenesis ; Phosphoric Acids ; Sulfur ; Sulfuric Acids ; Titanium

This study was aimed to investigate the effects of bortezomib combined with 5-azacytidine on the apoptosis of K562 cells and expressiom of SHIP mRNA. The K562 cells were cultured and treated with different concentrations of bortezomib, 5-azacytidine or their combination for 24 hours. Then, the expression of SHIP mRNA was detected by RT-PCR,the cell proliferation was analyzed by using MTT assay and flow cytometry. The results showed that 5-20 nmol/L bortezomib could effectively inhibit the proliferation of K562 and this inhibitory effect gradually enhanced along with the increase of bortezomib concentration, the group of bortezomib combined with 5-azacytidine showed more inhibitory effect on K562 cells than that of bortezomib or 5-azacytidine alone.The bortezomib could promote the apoptosis of K562 cells in a dose-dependent manner,and this apoptotic effect was higher in group of bortezomib combined with 5-azacytidine than that in group of bortezomib or 5-azacytidine alone.Bortezomib could down-regulated the expression of SHIP mRNA in a dose-dependent manner,and this down-requlated effect was higher in group of bortezomib combined with 5-azacytidine than that in group of bortezomib or 5-azacytidine alone.It is concluded that bortezomib and 5-azacytidine can induce apoptosis by inhibiting the expression of SHIP mRNA in K562 cells.The combination of bortezomib with 5-azacytidine displays a synergetic effect.
Apoptosis ; drug effects ; Azacitidine ; pharmacology ; Boronic Acids ; pharmacology ; Bortezomib ; Cell Proliferation ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; Phosphoric Monoester Hydrolases ; genetics ; Pyrazines ; pharmacology ; RNA, Messenger ; biosynthesis

OBJECTIVE: The purpose of this study was to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on the shear bond strength (SBS) of brackets bonded to non-demineralized teeth with either phosphoric acid etching or self-etching primer. METHODS: Sixty human premolars were randomly assigned to 1 of 4 treatment groups (n = 15 each): phosphoric acid etching (group 1); self-etching primer (group 2); CPP-ACP for 2 weeks + phosphoric acid etching (group 3), and CPP-ACP for 2 weeks + self-etching primer (group 4). After bonding of the maxillary premolar metal brackets, specimens were subjected to shear forces in a testing machine. Scanning electron microscopy was used to observe etching patterns on the enamel surfaces of all teeth. A 2-way analysis of variance was used to test for effects of CPP-ACP and etching system on SBS. RESULTS: Significantly higher mean SBSs were observed in groups subjected to phosphoric acid etching (i.e., groups 1 and 3; p < 0.05). On the other hand, SBSs did not appear to be influenced by CPP-ACP (i.e., groups 3 and 4; p > 0.05). We observed a uniform and clear etched pattern on the enamel surface of the phosphoric acid etching groups. CONCLUSIONS: CPP-ACP does not significantly affect the SBS of orthodontic brackets bonded to non-demineralized teeth, regardless of which adhesive method is used to bond the brackets.
Adhesives ; Bicuspid ; Calcium ; Calcium Phosphates ; Caseins ; Dental Enamel ; Hand ; Humans ; Microscopy, Electron, Scanning ; Orthodontic Brackets ; Phosphoric Acids ; Tooth

This study was aimed to investigate the effects of proteasome inhibitor bortezomib on proliferation, apoptosis and the SHIP expression of K562 cells. K562 cells were treated with bortezomib of different concentrations. Cell proliferation was analyzed by MTT assay, cell apoptosis was detected by flow cytometry and SHIP mRNA expression was assayed by RT-PCR.The results showed that after being treated with 10, 20, 50 and 100 nmol/L bortezomib for 24 h, the inhibitory rates of K562 cells were (5.76 ± 1.47)%, (10.55 ± 1.59)%, (17.14 ± 2.05)% and (27.69 ± 3.57)% respectively, and were higher than that in control (1.30 ± 0.10); when K562 cells were treated with 20 nmol/L bortezomib for 24, 48 and 72 h, the inhibitory rates of cell proliferation were (10.55 ± 1.59)%, (16.33 ± 2.53)% and (19.78 ± 1.56)% respectively, there was statistic difference of cell proliferation rate between 24 h group and 48 h group (P < 0.05). After being treated with 10,20,50,100 nmol/L bortezomib for 24 h, the apoptotic rates of K562 cells were (12.7 ± 0.6)%, (26.9 ± 0.9)%, (32.6 ± 1.2)% and (72.5 ± 1.5)% respectively,and all higher than that in control (1.0 ± 0.5)% (P < 0.05). According to results of RT-PCR detection, the expression level of SHIP mRNA was obviously up-regulated after treatment with bortezomib, and showed statistical difference in comparison with control. It is concluded that bortezomib inhibits proliferation of K562 cells in time and concentration-dependent manner and induces apoptosis through up-regulation of SHIP gene.
Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Boronic Acids ; pharmacology ; Bortezomib ; Cell Proliferation ; drug effects ; Humans ; Inositol Polyphosphate 5-Phosphatases ; K562 Cells ; Phosphoric Monoester Hydrolases ; genetics ; metabolism ; Proteasome Inhibitors ; pharmacology ; Pyrazines ; pharmacology

Boronic Acids ; Bortezomib ; Humans ; Liver Diseases ; Proteasome Inhibitors ; Pyrazines

According to National Emergency Management Agency in Korea, numbers of death and injured in firefighters were 34 and 1,555 persons, respectively, between 2003 and 2007. Firefighting is a very dangerous and difficult work because of physical, chemical, and biological hazards. Firstly, physical hazards include burn induced by smoke and other combustion products, heat, noise, and ergonomic factors. Secondly, chemical hazards include chemical asphyxiants such as carbon monoxide, hydrogen cyanide, and hydrogen sulfide, simple asphyxiants such as carbon dioxide, chemical irritants including as hydrogen chloride, and acrolein, and so on, and other carcinogens. Finally, biological hazards include infectious agents such as hepatitis, tuberculosis, and so forth. We expect this study to help management andpromotion of firefighters' health.
Acrolein ; Biological Factors ; Burns ; Carbon Dioxide ; Carbon Monoxide ; Carcinogens ; Emergencies ; Firefighters ; Fires ; Hepatitis ; Hot Temperature ; Humans ; Hydrochloric Acid ; Hydrogen Cyanide ; Hydrogen Sulfide ; Irritants ; Korea ; Noise ; Smoke ; Tuberculosis