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PubMed2003

Spirometric measurements among quartz stone ex-workers of Gujarat, India.

The present cross sectional study was carried out among 134 ex-workers from quartz stone crushing units. Using the interview technique as a tool for data collection, demographic and occupational details of the subjects were recorded on the predesigned proforma. Standard diagnostic criteria were used for diagnosing silicosis and silico-tuberculosis. The pulmonary functions of the subjects were measured with Spirovit SP-10. The mean age of the males was found to be 33.18 +/- 10.39 yr and that of the females was 30.10 +/- 9.3 yr and for the whole group was 31.77 +/- 9.99 yr. Mean duration of exposure was 2.74 +/- 1.65 yr. The study variables included age, sex, duration of exposure, smoking and respiratory morbidity. Forced Vital Capacity (FVC) which suggests lung parenchymal disorders was found to be significantly reduced with female sex, presence of smoking, increasing duration of exposure and presence of pneumoconiosis, whereas the lung function parameters indicating the status of airways were found to be significantly reduced with all the factors. Therefore, it was concluded that quartz stone workers exposed to approximately 100% free silica had deteriorated lung function which can be attributed mainly to respiratory disorders along with other epidemiological factors such as age, sex, duration of exposure and smoking.

Adult↗
PubMed1986

Toxicological evaluation of quartz and silica contents in studded tire-generated dust in the city of Sendai.

Roadside dust samples were collected at six locations in the City of Sendai at the end of the winter season of 1980-1981, and analyzed for quartz and silica contents. X-ray diffraction and ICP analyses revealed that the mean quartz and silica contents in dust samples were 14.6% (ranging from 12.2 to 19.4%) and 56.3% (53.7 to 59.7%), respectively. From these results in connection with current dust levels and estimated duration of exposure, it appears likely that the risk of silicosis among the citizens may not be high if appropriate measures are taken to protect the atmosphere.

Quartz↗
PubMed2003

Quartz-crystal microbalance immunosensor for Schistsoma-japonicum-infected rabbit serum.

A quartz-crystal microbalance immunosensor (QCM) has been developed for the direct determination of Schistosoma-japonicum-infected rabbit serum. A self-assembled monolayer with carboxyl groups was first coated on a gold electrode of a quartz-crystal resonator by the spontaneous adsorption of 3-mercaptopropionic acid. Schistosoma-japonicum molecular antigen of 32 kD molecular weight was then covalently attached to the crystal surface. The QCM immunosensor was used to detect infected rabbit serum (IRS49-2000); a maximum titer of 1:800 was achieved.

3-Mercaptopropionic Acid↗
PubMed2005

Study on degradation characteristics of chitosan by pepsin with piezoelectric quartz crystal impedance analysis technique.

Piezoelectric quartz crystal impedance analysis technique was applied to study the chitosanolytic activity of pepsin. The method is based on the viscosity-density reduction of chitosan solution during the enzymatic degradation process. Experiments examined the time courses of the variations of motional resistance (deltaR1) for a quartz crystal. By comparing the deltaR1 response curves under different degradation conditions, the effects of pH, temperature, enzyme and substrate concentration on the chitosanolytic activity of pepsin was investigated in detail. The results suggest that the optimum pH and temperature were 4.6 and 55 degrees C, respectively. Increasing aptly the enzyme or substrate concentration was in favor of the degradation of chitosan. Moreover, the influence of the degree of deacetylation (DD) on the enzymatic degradation was studied. The result indicates that chitosan with a lower DD was easier to be degrade compared with chitosan with a higher DD. Also, it was found that there was a good linear relationship between the deltaR1 response and the DD value. The regression equation was deltaR1 = 0.058 x DD-6.795 and the correlation coefficient was 0.987.

Chemical Phenomena↗
PubMedDate not supplied

Adsorption of pesticides onto quartz, calcite, kaolinite, and alpha-alumina.

The fate of pesticides in aquifers is influenced by the small but not insignificant adsorption of pesticides to mineral surfaces. Batch experiments with five pesticides and four minerals were conducted to quantify the contributions to adsorption from different mineral surfaces and compare adsorption characteristics of selected pesticides. Investigated mineral phases included quartz, calcite, kaolinite, and alpha-alumina. Selected pesticides comprised atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine), isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea)], mecoprop [(RS)-2-(4-chloro-2-methylphenoxy)propionic acid], 2,4-D (2,4-dichlorophenoxyacetic acid), and bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide]. Specific surface area and mineral surface charge proved to be important for the adsorption of these pesticides. Detectable adsorption of the anionic pesticides (mecoprop, 2,4-D, and bentazone) was only measured when positive sites were present on the mineral surface. However, when CaCl2 was added as an electrolyte, a detectable adsorption of mecoprop and 2,4-D was also measured on kaolinite (which exhibits a negative surface charge), probably due to formation of Ca-pesticide--surface complexes. Adsorption of the uncharged pesticides (atrazine and isoproturon) was detected only on kaolinite. The lack of adsorption on alpha-alumina indicates that the uncharged pesticides have a greater affinity for the silanol surface sites (=SiOH) than for the aluminol surface sites (=AlOH) in kaolinite. No measurable effect of ionic strength was found for the uncharged pesticides. The results indicate that quartz and calcite play a smaller role than clay minerals.

Adsorption↗
PubMed1996

Equivalent diameter of standard quartz dust used as a test aerosol for the dust respirator.

In the standard of the approval test for dust respirator certification, test aerosols are defined as air containing quartz particles of 2 microns or smaller1. However, it is well-known that the filtration efficiency of air filters depends on the size of the test aerosol particles. Alternative test aerosols containing submicron size particles will be studied for use in future approval test of dust respirators. Before searching for alternatives, characterization of currently-used quartz dust, e.g. information about size and electrostatic charge of the aerosol particles, should be determined. The currently-used approval test measures filtration efficiencies with a light scattering photometer. The photometer gives overall aerosol concentration, while Aerodynamic Particle Sizer (APS-33B, TSI Inc., St. Paul, U.S.A.) is able to give the number concentration for each particle size based on the aerodynamic diameter ranging from 0.9 to 2.0 microns. In this study, equivalent diameter was defined as the diameter at which penetration has the same value when measured by APS-33B and by light scattering photometer. The equivalent diameter for the ten filter samples for dust respirator was around 1 microns, irrespective of neutralization of the test aerosol.

Aerosols↗
PubMed1983

Dose-dependent effects in the subacute response of the rat lung to quartz. I. The cellular response and the activity of lactate dehydrogenase in the airways.

The response of the rat lung to a range of doses of quartz at 50 and 100 days after its administration by intratracheal instillation was investigated by bronchopulmonary lavage. The effects on the numbers of polymorphonuclear leucocytes, lymphocytes and macrophages recovered are described. In addition, the size distribution of the recovered macrophages was followed and measurements of total numbers of macrophages in the lung were made using a radioactive tracer technique. Finally, the activity of the cytoplasmic enzyme, lactate dehydrogenase, in lavage fluid supernatants was recorded. There was a dose-dependent increase in the recovery of all three cell types and an increase in the total numbers of macrophages in the lungs which showed no signs of resolution over the 100 day period studied. Increasing levels of lactate dehydrogenase were also dose-dependent and well correlated with the numbers of polymorphs and lymphocytes recovered. The importance of this prolonged inflammatory reaction in relation to the fibrogenic action of quartz is discussed.

Animals↗
PubMed1989

Effect of particle size on quartz-induced hemolysis and on lung inflammation and fibrosis.

To assess the role of crystal size in biologic responses, we quantitated red blood cell lysis and lung inflammation and fibrosis in the mouse using 4 alpha-quartz preparations with average diameters of 1, 5, 7.8, and 11.2 microns. When compared on the basis of identical crystal surface areas, the 1-micron fraction was more hemolytic than the other 3 fractions. The three larger fractions had equivalent membranolytic activities. After 6 weeks of postintratracheal instillation of the crystals into mice, the 1-micron-diameter crystal fraction increased wet lung weights by 1.25 x that of saline controls, while a 1.75 x increase was found for the three larger crystal fractions. A similar response was found when evaluating fibrosis development by determining lung hydroxyproline levels. Measurement of the percentage of the crystal dose remaining in the lungs revealed that the biologic differences observed were not due to a difference in the clearance of the smaller crystal fraction. Thus, larger crystals of alpha-quartz produce a greater degree of inflammation and fibrosis when instilled into the lung than those of 1 micron diameter, even though the smaller crystals are more membranolytic in vitro and appear to be cleared from the lung at the same rate as the larger crystals.

Animals↗
PubMed1987

An improved negative staining technique using a thin quartz membrane as sample support.

A negative staining technique is presented based on the use of 40-60 nm quartz membrane supported by a silicon grid. The quartz membrane is fabricated by thermal growth of silicon dioxide on a silicon substrate followed by an anisotropic silicon etching step giving rectangular holes in the silicon substrate. The hydrophilic membrane is shown to be ideally suited for negative staining due to its spreading characteristics, homogeneity, heat resistance and mechanical stability. Micrographs of phage lambda are presented showing the detailed structure of the tail. A simple method of calculating the number of adsorbed particles based on diffusion limited association is also presented.

Microscopy, Electron↗
PubMed2003

Real-time monitoring of apatite deposition using electrochemical quartz crystal microbalance.

The electrochemical deposition process of apatite was monitored in real-time using an electrochemical quartz crystal microbalance (EQCM). A piezoelectric quartz oscillator with titanium was fixed to a cell and connected to a frequency counter. The electrolyte temperature was maintained at 20, 37, and 60 degrees C and the direct current density was constant at 0.2, 0.5, 1.0, and 2.0 mA/cm2. The deposited amount derived from the frequency change increased as electrolyte temperature and current density increased. The critical times, which are the starting times of quick increases of deposition, decreased with them. The critical times observed in the present study, namely in situ, were much shorter than those obtained from real weight change reported in our previous report. The apparent activation energies of the electrochemical deposition of apatite under 1.0 and 2.0 mA/cm2 were about 36.1 and 31.9 kJ/mol, respectively. These results indicate that electro current loading may reduce the activation energy required for the deposition of calcium phosphates.

Adsorption↗
PubMed2001

Anatomical post design meets quartz fiber technology: rationale and case report.

Endodontically treated teeth frequently require a post and core to serve as a foundation for the coronal restoration. Remaining tooth structure, physical properties of the post material, post shape, and cement type all contribute to the success of the restoration. Post adaptation to the canal walls also represents an important element in the biomechanical performance of the prosthetic restoration. A double taper post system made of quartz fiber and epoxy was developed to conform more precisely to the shape of endodontically treated canals. Immediate benefits of this post system include minimal tooth structure removal during canal reshaping, greater post-to-canal adaptation in the apical and coronal half of the canal, and good post retention. The use of a quartz fiber/epoxy material with a lower modulus of elasticity also reduces the incidence of root fracture. Furthermore, the esthetic nature of the colors offered with this post system (translucent and off-white) provide a favorable foundation for eliminating discoloration caused by a metallic post placed under all-ceramic crown systems.

Adult↗
PubMed2002

Determination of alpha-fetoprotein in human serum by a quartz crystal microbalance-based immunosensor.

BACKGROUND: Increased alpha-fetoprotein (AFP) in adult plasma is considered an early indication of hepatocellular carcinoma and teratoblastoma. The aim of this study was to develop a rapid method to measure AFP in human serum by use of a direct immunosensor based on a quartz crystal microbalance (QCM). METHODS: A self-assembled monolayer prepared by the cystamine method was applied to immobilize anti-AFP monoclonal antibodies on the gold surface of a quartz crystal. The frequency shifts of the QCM were measured and related to AFP concentrations. The piazoimmunosensor used no labeled reagent and no pretreatment of samples. RESULTS: Ten cycles of measurements could be performed on the gold surface of the same crystal regenerated with a solution of glycine-HCl. A linear relationship existed between the frequency shifts (Hz) and the log values of AFP concentrations from 0.1 to 100 microg/L in buffer and human serum. When used for 15 days, the frequency shifts were all >95% of those on the response at the first day. The regression equation was y = 1.03x - 0.06 (S(y/x) = 3.92; r = 0.9987) for this QCM method and RIA in 29 clinical human serum samples. CONCLUSIONS: The QCM sensor can measure AFP in buffer and human serum and offers advantages of high specificity, reusability, low detection limit, no label or sample pretreatment, and low sample requirement. The assay format of the immunosensor was more rapid and simpler than conventional methods.

Antibodies, Monoclonal↗
PubMed1992

[Expression of TNF-alpha in alveolar macrophages after stimulation with quartz dust, welding fume dust and asbestos fibers].

Alveolar macrophages have a potential for expressing and excreting many factors that are immunologically active and active on cytokines (monokines and lymphokines) and are thus indirectly involved in the genesis of pulmonary fibroses. One of these factors is the tumour necrosis factor alpha (TNF alpha). In the study presented here, the expression of TNF alpha-mRNA was investigated in macrophages stimulated in vitro with quartz dust, dust from cinders of welding furnaces, and asbestos, using non-radioactive in situ hybridization. There was a marked dependence of the expression of this cytokine on both time and stimulation. Macrophages stimulated by quartz dust showed the highest rate of expression compared with controls and other related stimuli. In addition, all stimuli yielded an expression that was elevated for a short period only and reached its peak after four hours. The results permit the conclusion that various professionally inhaled dusts possess different risk potentials in respect of lung damage mediated by macrophages and do not behave uniformly.

Animals↗
PubMed2004

[Advances in piezoelectric quartz crystal biosensor and its applications].

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↗
PubMed2004

[Study on interaction of Radix Paeoniae 801 and endothelin-1 by using a piezoelectric quartz crystal biosensor].

OBJECTIVE: To explore the possible target and molecular mechanism of Radix Paeoniae 801 (RP801), an effective ingredient extracted from Radix Paeoniae, the Chinese herbal medicine for activating blood circulation to remove blood stasis, using experimental in vitro method by directly detecting the interaction between RP801 and endothelin-1 (ET-1). METHODS: Piezoelectric quartz crystal biosensor, namely, the quartz crystal microbalance (QCM) was used to detect the specific combining between RP801 and ET-1 by binding avidin to the pre-activated Au surface of electrode of QCM, followed by immobilizing biotinylated ET-1 to it, and adding RP801, then the binding curve was recorded. PBS washing was applied at the end of every steps of combining reaction for dissociate the non-specific absorption. RESULTS: Specific combining of RP801 and ET-1 was found. CONCLUSION: ET-1 could possibly be one of the acting targets of RP801 in the body, that is, RP801 could combine with ET-1 to impede the binding of ET-1 with its receptor, so as to counteract the action of ET-1, dilate blood vessels and inhibit platelet aggregation.

Biosensing Techniques↗
PubMedDate not supplied

In vitro study of surface microhardness of a resin composite exposed to a quartz-halogen lamp.

OBJECTIVES: To determine the minimum exposure times consistent with optimized surface microhardness numbers (VHN) for the top and bottom surfaces, respectively, of a resin composite (1.5-mm depth) cured using a quartz-halogen activation lamp. Additionally, to determine the conditions appropriate to achieve optimized bottom/top hardness ratios. METHOD AND MATERIALS: Disk specimens of a commercial resin composite restorative (Spectrum TPH) were exposed to a quartz-halogen lamp, and VHNs were measured for the top and bottom surfaces at elapsed times of 1 hour and 24 hours. RESULTS: Data were dependent on exposure time, time elapsed after exposure, and the surface involved. Exposure time featured limiting values in excess of which no significant increase in microhardness took place. All microhardness data increased significantly over an elapsed time interval between 1 hour and 24 hours postexposure. Microhardness ratios (bottom/top) were dependent on exposure time only and were not influenced by time elapsed after exposure. CONCLUSION: Minimum exposure time may be considered as the greater of the times to achieve optimized top hardness and optimized hardness ratio, respectively.

Composite Resins↗
PubMed2004

Serum copper levels among quartz stone crushing workers: a cross sectional study.

The present cross sectional study was carried out among 134 workers of quartz stone crushing units to assess the serum Cu activity among quartz stone workers without disease. Demographic and occupational details of the subjects were recorded on the predesigned proforma. Standard diagnostic criteria were used for diagnosing silicosis and tuberculosis. The pulmonary functions of the subjects were measured using Spirovit SP-10. The mean age for male was found to be 26.63 +/- 6.28 years while that for female was 21.93 +/- 4.29 years and for the whole group was 26.13 +/- 6.26 years. In the present study only one case of silicosis and seven cases of tuberculosis were found. The mean serum Cu levels of those having respiratory disease was found to be 91.5 +/- 19.8 microg/dl while mean serum Cu level of those free from respiratory disease was 86.8 +/- 21.3 microg/dl The difference was found to be statistically non-significant (t = 0.64, df= 1, P > 0.05). Thus, in the present study, though the elevated level of serum Cu was found in solitary case of silicosis, no association could be established between the silica exposure and serum copper levels as suggested by non-significant effect of duration of exposure (P = 0.53).

Adolescent↗
PubMed2005

Retention of quartz-fibre endodontic posts with a self-adhesive dual cure resin cement.

This study examines retention of a quartz-fibre endodontic post cemented in extracted human teeth using two cement types. Fifty-four extracted buman central incisor teeth were prepared for a tapered quartz-fibre post. Posts were cemented in 28 teeth using conventional resin cement (RelyX ARC), and 26 teeth using self-adhesive resin cement (RelyX Unicem). Posts were cyclically-loaded. Bond strengths were tested and dependability assessment was carried out. Although there was no significant difference in Weibull modulus between groups (p < 0.05), greater dependability was displayed by RelyX Unicem group. Easy application and greater dependability of self-adhesive cement may improve bonding of fibre-based posts in root canals.

Bisphenol A-Glycidyl Methacrylate↗