Dust ; analysis ; Environmental Monitoring ; methods ; Silicon Dioxide ; analysis

Objective: To analyze the post distribution of dust concentration in ferrous metal foundry enterprises and evaluate the occupational health risks, and provide basis for policies of the formulation of pneumoconiosis prevention and control. Methods: From August to September in 2020, the basic information, dust hazard information and occupational health management information of 59 ferrous metal casting enterprises were investigated, the dust concentration distribution was analyzed, and the risk assessment was carried out by using the quantitative assignment model. The dust concentration is tested by LSD method after logarithmic treatment. The 3 times time weighted average allowable exposure concentration of dust is taken as the peak concentration limit of dust; The time weighted average allowable exposure concentration of dust converted by exposure time is taken as the time weighted average exposure concentration limit of dust, and whether the time weighted average exposure concentration and peak concentration of dust at the same post exceed the limit is taken as the basis for exceeding the limit of dust post concentration to calculate the post exceeding the limit rate. Results: The dust hazards were mainly distributed in the posts of sand treatment, molding, sand falling, sand cleaning and cutting and grinding. Dust exposure time weighted average concentration was 0.44 (0.03, 5.11) mg/m(3), peak exposure concentration was 1.30 (0.18, 10.94) mg/m(3), and the over standard rate of Posts was 38.92% (79/203) . Weighted average exposure concentration of other dust (total dust) in the cutting and grinding post is 1.50 (0.15, 7.40) mg/m(3), peak exposure concentration is 0.90 (0.07, 12.48) mg/m(3), and the post exceedance rate is 4.88% (2/41) . Weighted average exposure concentration of silica dust (exhaling dust) in dust operation posts of investment casting enterprises is 0.43 (0.05, 6.35) mg/m(3), peak exposure concentration is 0.90 (0.12, 8.28) mg/m(3), and the post over standard rate is 35.77% (49/137) ; Weighted average exposure concentration of other dust (total dust) at the cutting and grinding post is 2.00 (11.00, 21.00) mg/m(3), and the post exceedance rate is 2.50% (2/80) . There was no significant difference in the concentration of respirable dust between sand casting and investment casting (P>0.05) . The concentration of respirable dust in sand casting was higher than that in sand treatment, molding and sand cleaning posts (P<0.05) . The concentration of silica dust in investment casting was higher than that in sand treatment and molding posts, and that in sand cleaning posts was higher than that in sand treatment posts (P<0.05) . 98.48% (454/461) of the dust operation posts have an occupational health risk value greater than or equal to 400, and 1.52% (7/461) of the dust operation posts have an occupational health risk value of 200~399. Conclusion: there is a high rate of exceeding the standard in the dust work posts in the ferrous metal foundry enterprises in Ningbo, and the workers have a high occupational health risk of pneumoconiosis or metal and its compound pneumoconiosis. Targeted measures should be taken to reduce the occupational health risk.
Air Pollutants, Occupational/analysis* ; Dust/analysis* ; Humans ; Occupational Exposure/analysis* ; Pneumoconiosis ; Sand ; Silicon Dioxide/analysis*

OBJECTIVETo investigate the methods of determining aluminum silicate coated on the surface of silica particles and analyze the role of surface occlusion on development of silicosis.

METHODSRespirable dust samples were collected on filters using 2 L/min flow in tungsten mines and pottery factories of Jiangxi province, and tin mines of Guanxi province. Dust particles were analyzed by a multiple-voltage scanning electron microscopy-energy dispersive X-ray spectroscopy (MVSEM-EDS) using 20 KeV and 5 KeV electron beam accelerating voltages. Changes in the silicon to aluminum X-ray line intensity ratio between the two voltages are compared particle by particle. This provided an index that distinguishes a silica particle that was homogeneously aluminum-contaminated from a clay coated silica particle.

RESULTSThe total of 3,982 dust particles from 47 dust samples of seven pottery factories, three tin mines and three tungsten mines were analyzed in this study. Significant difference of aluminum silicate coated on the surface of silica particle was shown between particles from pottery factories and tin mines. The average sample percentage of respirbale-sized silica particles alumino-silicate occlusion in the pottery factories (45%) was higher than that in the tin mines (18%) and tungsten mines (13%).

CONCLUSIONHigher percentages silica particles alumino-silicate occlusion is observed in the pottery factories than that in metal mines. These surface analysis results help to understand differences in risk of silicosis when exposure is normalized to cumulative respirable surface silica dust.

Aluminum ; analysis ; Dust ; analysis ; Microscopy, Electron, Scanning ; Mining ; Silicon ; analysis ; Silicon Dioxide ; chemistry ; Spectrometry, X-Ray Emission

Objective: To understand the exposure level of dust and noise in the mining industry and provide data support for revising policy for the prevention and control of occupational diseases. Methods: In May 2022, Data was collected through the National Surveillance Program for Occupational Hazards in the Workplace. Descriptive analysis was conducted for dust and noise levels by industry type and enterprise size from 7, 679 enterprises in the mining industry among 29 provincial regions nationwide. Results: The enterprises in the mining industry included in the National Surveillance Program for Occupational Hazards in the Workplace are mainly small and micro, accounting for 47.97% (3684/7679) and 30.00% (230/7679) respectively. The industry is mainly compred of employers in the non-metallic ming and beneficiation industry, accounting for 50.25% (3859/7679). Among the enterprises with silica dust, coal dust, and noise hazards, the proportion of enterprises where total dust concentration and noise intensity exceed the standard is higher than 50%. 30% of the posts are with an exposure level of silica dust, coal dust, and noise that exceeds the standard. The exceedance rate and the median of the time-weighted average concentration of total coal dust among large and medium-sized enterprises are higher than those among small and micro-sized enterprises (P<0.05) . Conclusion: The dust and noise hazards in the mining industry are lower than in the past in China, but more than 25% of workers are still at a high risk of occupational pneumoconiosis and noise deafness. Therefore, intervention and surveillance strategies should be strengthened in the future.
Humans ; Dust/analysis* ; Occupational Exposure/analysis* ; Occupational Health ; Coal ; Silicon Dioxide/analysis* ; Coal Mining

OBJECTIVETo study the characteristics of the SiO2/R2O3 in non-zonal purple soil in the light of the difference between the high yield and low yield of Salvia miltiorrhiza.

METHODBoth the high yield and low yield drugs developed from the same parental material (k1cy) were chosen in the ecology area in Zhongjiang county, Sichuan Province. By using the air-dried drugs as sample, quadrat sampling method was used to calculat the production. Gravimetric method, volumetric method, and colorimetric method and neutralization titration were used to measure the content of adhesive particle colloids element in the soil. And T-test was used for the variable-difference analysis.

RESULTThere was a sharp contrast between the production of high yield and low yield drugs (P < 0.001). The characteristic value of the high yield soil embryology was much higher than that of the low yield soil.

CONCLUSIONThe characteristic value of the purple soil embryology is one of the important factors of the soil adaptability of the drug and its quality. The weathering degree of the soil is closely related to the yield of the drug.

Aluminum ; analysis ; Aluminum Oxide ; analysis ; Ecosystem ; Ferric Compounds ; analysis ; Iron ; analysis ; Plants, Medicinal ; growth & development ; Salvia miltiorrhiza ; growth & development ; Silicon ; analysis ; Silicon Dioxide ; analysis ; Soil ; analysis ; Titanium ; analysis

OBJECTIVETo analyze the influence of experimental conditions: Distribution of particulate and the filter condition on the pyrophosphoric acid method for quantitative analysis of free silica in dust.

METHODSAccording to Method for determination of dust in the air of workplace Part 3: Distribution of particulate (GBZ/T 192.3-2007) , Part 4: Content of free silica in dust (GBZ/T 192.4-2007) , the distribution of particulate of 5kinds of dust samples were observed. Different filter conditions were used to determinate the Content of free silica in the 4kinds ofdust samples: 1 filter paper, 2 filter papers, 3 filter papers, 2 filter papers with paper pulp in them.

RESULTSThe distribution of particulate of 4 kinds of dust sampleswere different. The order from high to low is defined with "I, II, III, IV, V" successively. For dust sample I, II, III, the results with different conditions increase successively (P<0.05) . The result in 2 filter papers with paper pulp were not significantly different compared with the reference value (P>0.05) . For dust sample IV, the resultin 1 filter paper were significantlylower thanthe reference value (P<0.05) . For dust sampleV, The results with different kinds of filter type were not significantly different (P>0.05) .

CONCLUSIONdifferent filter conditions should be considered according to thecontent of free silica and the distribution of particulate in dust sample. For the dust sample which has the higher content of free silica and the distribution of particulate, 2 filter papers with paper pulp in themis the better filter condition compared with the traditional way.

Air Pollutants, Occupational ; analysis ; Diphosphates ; Dust ; Environmental Monitoring ; methods ; Filtration ; Particle Size ; Silicon Dioxide ; analysis

OBJECTIVETo find a suitable method for detecting SiO2 in quartz sand and to analyze the influencing factors on infrared spectroscopic determination of the content of free silica in quartz sand.

METHODSThe infrared spectroscopy was used to detect the free silica content of quartz sand, the various factors of influencing the results were analyzed and the control scheme was proposed.

RESULTSThe number of particles less than 5 um and the proportion of free silica content increased with the grinding time. When the grinding time was 10-20 min, the results of detecting the free silica content tended to be stable. When the ashing temperature was below 550 degrees C, there was no effect on the free silica content. Although the silica content decreased slightly at ashing temperature 600 degrees C as compared to ashing temperature 550 degrees C, the difference of the free silica content between 550 degrees C and 600 degrees C was not significant (P > 0.05). When the ashing temperature was 600 degrees C, the free silica content in quartz sand samples did not change obviously in 1 h (F = 4.231, P > 0.05). The free silica content in quartz sand samples decreased significantly at 2 h of ashing time, as compared with 2 h of ashing time (F = 10.231, P < 0.05). The average content of free silica was 88.56% +/- 5.75% by pyrophosphate determination, which was significantly higher than that (21.23% +/- 11.25%) by infrared determination (P < 0.05). There was no significant correlation of the average content of free silica between pyrophosphate determination and infrared determination (r = 0.411, P > 0.05).

CONCLUSIONThe free silica contents detected by pyrophosphate determination were significantly higher than those detected by infrared determination for the same quartz sand samples. It is suggested that the method of detecting the free silica contents in quartz sand samples prefers the pyrophosphate determination to infrared determination.

Air Pollutants, Occupational ; analysis ; Occupational Exposure ; analysis ; Particle Size ; Quartz ; analysis ; Silicon Dioxide ; analysis ; Spectrophotometry, Infrared ; Workplace

Biochip technology will bring a tremendous revolution to life science and medical research in 21 century. Microarray assays represent an essential technical advance in biomedical research. Recently, the demand for microarray assay technology has spring up. Therefore, low cost and flexible techniques are needed to meet specific requirements for increasingly integrated biochips. Also performance must be improved in terms of speed and sensitivity. To this end, promising approaches, mainly based on micro and nanotechnologies, have been developed. In this paper, the design and microfabrication of a novel type of micro-cantilever probe are introduced. These probes were fabricated using silicon dioxide by Micro-electromechanical System (MEMS) techniques, and they featured one micron split gap, microchannels and self-replenishing reservoirs. All fabricated micro-cantilever probe were tested on Nanoarrayer instrumentation. Cy3-streptavidin was loaded as biological sample and patterned on DSU gold surface. Results showed these probes were capable of generating high quality biological arrays with routine spot sizes of 2 - 3 microns and could deposit at least three thousand spots without reloading. The spot size could potentially achieve sub-micron when probe size was further shrunk down by the high-resolution lithography technique or more precise microfabrication technologies, such as E-beam lithography. To further improve sample loading efficiency, it is needed to modify the cantilever surface in order to better confine sample inside the microchannel and reservoir, which will be researched in the future.
Microarray Analysis ; instrumentation ; methods ; Microelectrodes ; Molecular Probe Techniques ; instrumentation ; Nanotechnology ; instrumentation ; methods ; Silicon Dioxide ; chemistry

The purpose of this study was to investigate the distribution of tensile stress of canal obturated maxillary second premolar with access cavity and notch-shaped class V cavity restored with composite resin using a 3D finite element analysis. The tested groups were classified as 8 situations by only access cavity or access cavity with notch-shaped class VS cavity (S or N), loading condition (L1 or L2), and with or without glass ionomer cement base (R1 or R2). A static load of 500 N was applied at buccal and palatal cusps. Notch-shaped cavity and access cavity were filled microhybrid composite resin (Z100) with or without GIC base (Fuji II LC). The tensile stresses presented in the buccal cervical area, palatal cervical area and occlusal surface were analyzed using ANSYS. Tensile stress distributions were similar regardless of base. When the load was applied on the buccal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth with class V cavity were slightly higher than that of the tooth without class V cavity. When the load was applied the palatal cusp, excessive high tensile stress was concentrated around the loading point and along the central groove of occlusal surface. The tensile stress values of the tooth without class V cavity were slightly higher than that of the tooth with class V cavity.
Acrylic Resins ; Bicuspid ; Finite Element Analysis ; Glass Ionomer Cements ; Morpholines ; Oxazolidinones ; Silicon Dioxide ; Tooth

Objective: Differential flora and differential metabolites shared by the intestinal and respiratory tracts of rats were screened to analyze the possible role of changes in intestinal flora and metabolites in the progression of pneumoconiosis in rats. Methods: In April 2020, 18 SD rats were randomly divided into three groups (control group, coal mine dust group and silica group, 6 in each group) , rats in the coal mine dust group and silica group were perfused with 1 ml of 50 mg/ml coal mine well dust suspension and silica suspension by nontracheal exposure, respectively. While rats in the control group were perfused with an equal dose of sterilized normal saline. Twenty four weeks after dust staining, rat feces, throat swabs, and lung lavages were collected. 16SrDNA gene sequencing and UHPLC-QTOF-MS untargeted metabolomics were used to analyze the flora and metabolites in feces, throat swabs and lung lavage fluid of rats in each group, to screen for shared differential flora and shared differential metabolites in intestinal and respiratory tract, and the correlation analysis between the differential flora and metabolites was performed using Spearman's statistics. Results: Compared with the control group, a total of 9 species shared differential flora between intestinal and respiratory tract were screened at phylum level, and a total of 9 species shared differential genus between intestinal and respiratory tract were screened at genus level in the coal mine dust group, mainly Firmicutes, Actinobacteria, Streptococcus, Lactobacillus, etc. Compared with the control group, a total of 9 shared differential flora were screened at the phylum level, and a total of 5 shared differential genus were screened at the genus level in the silica group, mainly Proteobacteria, Actinobacteria, Allobactera, Mucilaginibacter, etc. Compared with the control group, a total of 7 shared differential metabolites were screened for up-regulation of Stigmatellin, Linalool oxide and Isoleucine-leucine in both intestinal and respiratory tract in the coal mine dust group. Compared with the control group , a total of 19 shared differential metabolites werescreened in the silica group, of which Diethanolamine, 1-Aminocyclopropanecarboxylic acid, Isoleucine-leucine, Sphingosine, Palmitic acid, D-sphinganine, 1, 2-dioleoyl-sn-glycero-3-phosphatidylcholine, and 1-Stearoyl-2-oleoyl-sn-glycerol 3-phosphocholine were up-regulated in both the intestinal and respiratory tract. Conclusion: There is a translocation of intestinal and respiratory flora in pneumoconiosis rats, and rats have an imbalance of lipid metabolism during the progression of pneumoconiosis.
Rats ; Animals ; Isoleucine ; Leucine ; Coal Mining ; Rats, Sprague-Dawley ; Pneumoconiosis ; Dust/analysis* ; Silicon Dioxide ; Coal