Endotoxin is an important factor which can lead to endotoxemia and complication. Accurate detection of its concentration is very useful for the diagnosis and treatment of these diseases. A piezoelectric biosensor for detecting endotoxin was developed, which was based on liquid damping effect of quartz crystal resonator. The test results showed that the maximal frequency shift of sensor is linearly dependent on the logarithm value of concentration of endotoxin (0.1 pg/m - 10 ng/ml). The time which d (deltaf)/dt(maax) appeared in frequency shift curve was also linearly dependent on the logarithm value of concentration of endotoxin (0.01 pg/ml - 10 ng/ml). The detection time was shortened and the minimal limit of detection was decreased using the second method. Thus the proposed sensor is much simpler, more precise and has more lower limit of detecting detection of endotoxin when compared with the conventional methods.
Animals ; Biosensing Techniques ; instrumentation ; Endotoxins ; analysis ; Equipment Design ; Quartz ; Rabbits

In order to investigate working conditions of underground coal mines, this work was undertaken to evaluate the respirable dust and the concentration of quartz in Taeback and Kangneung areas. The concentration of quartz was determined by Fourier Transform Infrared Spectrophotometry. The results were as follows; 1) The concentration of respirable dust of drilling and coal face in Taeback and Kangneung areas were as followed. 2) Distribution of respirable dust was well fitted to the long-normal distribution and geometric mean value was log(-1) 0.37+/-log(-1) 0.47 (2.34+/-2.95) mg/m3. 3) The difference of respirable dust concentrations in Taeback and Kangneung areas was not significant statistically (p>0.05). 4) The concentration of quartz of drilling and coal face in Taeback and Kangneung areas were as followed. 5) Distribution of quartz concentrations was well fitted to the log-normal distribution and geometric mean value was log(-1) 0.33+/-log(-1) 0.45 (2.14+/-2.82)%. 6) The difference of quartz concentrations in Taeback and Kangneung areas was not significant (p>0.05), but significant at drilling sites and coal faces (p<0.05).
Coal* ; Dust* ; Fourier Analysis ; Gangwon-do* ; Quartz* ; Spectrophotometry, Infrared

A Fourier transform infrared spectrophotometric method was described for the determination of quartz, mica(sericite) and feldspar(potassium feldspar) in respirable dust in Taebaek area. The results were as follows; 1) The concentration of minerals were determined from the intensity of absorption peak of quartz at 799 cm-1, sericite at 539 cm-1, and potassium feldspar at 648 cm-1 respectively. 2) The precision(C. V. %) for the quartz determination was 7.70+/-2.68 % from 10 to 200 microgram of quartz. 3) The precision for the sericite determination was 16.34+/-6.82 % from 30 to 500 microgram of serictite. 4) The precision for the potassium feldspar determination was 5.28+/-1.74 % from 30 to 500 microgram of potassium feldspar. 5) The concentration of respirable dust in Taebaek area was 4.90+/-3.29 mg/m3(0.4-93.7%), percent quartz was 1.80+/-4.14% (0.01-20.56%), percent sericite was 11.37+/-6.43% (0.00-29.69%), percent potassium feldspar was 8.15 % (n=7, 3.41-19.70%). 6) The difference of respirable coal dust, quartz, and sericite concentration in drilling, coal cutting, hauling and separating was significant respectively (p<0.05).
Absorption ; Coal ; Dust* ; Fourier Analysis* ; Minerals ; Potassium ; Quartz* ; Spectrophotometry, Infrared*

Dust ; analysis ; Humans ; Mining ; Occupational Exposure ; prevention & control ; Quartz ; analysis ; Spain

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

Adolescent ; Adult ; Dust ; analysis ; Female ; Health Status ; Humans ; Industry ; Male ; Middle Aged ; Occupational Exposure ; analysis ; Quartz ; Young Adult

Piezoelectric quartz crystal biosensor is a new sensor developed with the comprehensive utilization of the high sensitivity to mass and the surface characteristics of quartz crystal such as density, viscosity, dielectric constant, conductance, and the high specificity of biologic identification molecules. It has the features of high sensitivity, high specificity, simple operation, high analysis speed, low cost, small size, on-line detection, etc. It can be of wide application in the areas of medical laboratory diagnosis, environment monitor, foods sanitary control and industrial production. In this paper, the fundamental principle, structure and its applications are reviewed.
Biosensing Techniques ; instrumentation ; methods ; Crystallization ; DNA, Viral ; analysis ; Elasticity ; Electrodes ; Equipment Design ; methods ; HIV ; isolation & purification ; Microchemistry ; Quartz

Artificial quartz dust exposure may cause associated pneumoconiosis. From November 2019 to July 2020, a total of 27 cases of silicosis associated with artificial quartz stone manufacturers were diagnosed and treated in the Occupational disease Department of Suzhou Fifth People's Hospital. The average age of onset was (46.8±6.6) years, and the average working age of dust exposure was (5.7±1.7) years.The main feature of high KV chest radiography is P/S shadow with strip shadow. CT imaging findings showed diffuse small nodules and ground glass shadows with band shadows. The lesions were mainly distributed in the upper lung, accompanied by pleural thickening, lymphadenopathy and calcification. The pulmonary function impairment was mainly mild restrictive ventilation disorder, and the bronchial mucosa longitudinal plica was the main manifestation under tracheoscopy. The age of silicosis of workers in artificial quartz stone production enterprises is younger, the working age of dust exposure is short, the lung function and bronchial mucosa have a certain degree of damage, and effective preventive measures should be taken in time.
Adult ; Child ; Child, Preschool ; Dust ; Humans ; Middle Aged ; Occupational Exposure/adverse effects* ; Pneumoconiosis/complications* ; Quartz/analysis* ; Silicosis/diagnosis*

Air Pollutants, Occupational ; adverse effects ; analysis ; Dust ; analysis ; Environmental Monitoring ; instrumentation ; methods ; Humans ; Industry ; Inhalation Exposure ; statistics & numerical data ; Maximum Allowable Concentration ; Occupational Exposure ; statistics & numerical data ; Quartz

This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading. Fifty extracted single-rooted mandibular premolars were randomized into five groups. Each group was prepared according to numbers of residual walls ranged from 0 to 4. Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts. In no-post groups, gutta percha point 2 mm below cemento-enamel junction was removed. Composite resin was adapted to the well and used to shape the core directly. Each tooth was restored with a complete metal crown. Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles. Then a quasi-statically load was applied in a universal testing machine 30° to the long axis with a crosshead speed of 1 mm⋅min(-1) until fracture. Data were analyzed with one-way analysis of variance and pairwise comparison (P<0.05). No specimens failed during dynamic loading. The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant (P<0.05). Placement of fiber posts had a significant effect when fewer than two walls remained (P<0.05), but it had no significant influence in groups with two, three or four walls (P>0.05). Fiber post did not change failure mode, and the fracture pattern was mainly favorable. More dentin walls need to be retained in clinic. When no less than two walls remained, a fiber post is not always necessary.
Analysis of Variance ; Bicuspid ; Composite Resins ; Dental Restoration Failure ; Dental Stress Analysis ; Dentin ; physiology ; Humans ; Post and Core Technique ; Quartz ; Tooth Fractures ; prevention & control ; Tooth, Nonvital