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At least 1,027 records · Page 57Linked to original sources
PubMed2000

Dynamic viscoelastic properties of photo-activated composite resins containing short glass fibres.

The dynamic shear modulus in torsion (G'), water absorption, thermal expansion and residual monomer of the reinforced materials produced by adding four short glass fibres (19 microm in mean diameter and 86.1--763 microm in mean length) and one spherical E glass (11.1 microm in mean diameter) were examined and discussed in comparison with those of the materials without filler. G' of short fibre reinforced composites increased with fibre length and reached a maximum value near 382 microm for a dry specimen and near 156 microm for a wet one. In addition, the coefficient of thermal expansion of the fibre reinforced composites and the amount of residual monomer decreased considerably compared with those of composites containing spherical glass. There was no significant difference in water absorption between the fibre reinforced composites and the composites containing spherical glass. Therefore, it was concluded that the reinforcement method of adding short glass fibres is favourable for improving the viscoelastic properties of the materials.

Absorption↗
PubMed2001

Morphology of glass fibers in electronics workers with fiberglass dermatitis--a scanning electron microscopy study.

BACKGROUND: Fiberglass is used as a reinforcement filler material in printed circuit boards (PCBs) which are widely used in the electronics industry. In a recent survey, we demonstrated that fiberglass dermatitis is the most common occupational dermatosis among electronics industry workers in Taiwan. Little is known, however, about the morphologic structures of the glass fibers which induce dermatitis. The purpose of this study was to assess the morphology of fiber spicules and to determine the relationship of this structure to fiberglass dermatitis. METHODS: Fourteen female patients with a diagnosis of fiberglass dermatitis were selected for study. The diagnosis was confirmed in all patients by positive skin stripping for glass fibers and matching with glass fibers from dust collected in work areas and from samples collected by scraping the edge of PCBs. Samples of collected glass fibers were analyzed by scanning electron microscopy (SEM). RESULTS: SEM of the fiberglass samples revealed that fibers were approximately 10 microm in diameter. In samples from both the edge of PCBs and from dust collected in work areas, SEM revealed that most of the fibers were in bundles of various sizes and lengths. All fibers collected from patients' skin by tape stripping showed a singular spicule, most had a sharp free end, and the lengths were in the range 50-150 microm . CONCLUSIONS: Singular glass fibers with a sharp free end and a length of 50-150 microm are most likely to induce fiberglass dermatitis.

Adult↗
PubMed2003

Bond strength for orthodontic brackets contaminated by blood: composite versus resin-modified glass ionomer cements.

PURPOSE: The purpose of this study was to evaluate and compare the shear bond strengths of a self-cured glass ionomer versus composite cement for bonding of stainless steel buttons with various enamel surface and setting conditions. MATERIALS AND METHODS: Stainless steel orthodontic buttons were bonded using composite material under 3 different enamel and setting conditions: 1) conditioned and dry enamel surface, 2) conditioned and precontamination of the enamel surface with blood before bonding, 3) conditioned and immediate blood contamination postbonding and were compared with 3 different enamel conditions and setting for bonding with the glass ionomer cement: 1) nonconditioned and wet enamel surfaces, 2) nonconditioned and blood contamination of enamel before bonding, and 3) nonconditioned and immediate blood contamination postbonding. The brackets were bonded to 109 recently extracted teeth and allowed to set in a moist plastic container for 24 hours. They were subsequently tested in shear mode with a universal testing machine. The maximum bond strength and the site of bond failure were recorded. In addition, the location of the bond failure was studied. RESULTS: Composite was capable of sustaining greater forces than the resin-modified glass ionomer materials. Hence, it took more force to debond a bracket cemented with composite than with resin-modified glass ionomer. The effect of contamination was similar in both of the materials, and the magnitude of the decrease in bond strength was nearly of the same proportion. The postcontamination values were not significantly different from the uncontaminated bond strength for either material. The type of bond failure was significantly different for the different materials, and there were significant differences among the treatment conditions. CONCLUSION: Composite resin had significantly greater shear strength than resin-reinforced glass ionomer cement. Both materials showed a significant decrease in bond strength when precontaminated with blood. The postcontamination values were not significantly different from the uncontaminated bond strength for either material.

Acrylic Resins↗
PubMed1999

Genetic alterations of cancer-related genes in glass fiber-induced transformed cells.

Our previous studies have shown that glass fibers induced morphological transformation in BALB/c-3T3 cells and that transformed cells possessed preneoplastic properties and transforming genes. In the current study, possible molecular mechanisms of glass fiber-induced cell transformation related to the activation and/or inactivation of cancer-related genes resulting from gene amplification and/or point mutations were investigated. Gene amplification was determined by Southern blot analysis of K-ras, H-ras, c-myc, and c-fos proto-oncogenes. Mutational spectra of the p53 tumor suppressor gene and the K-ras proto-oncogene were characterized by single-stranded conformation polymorphism and DNA sequencing. Southern blot analysis showed that gene amplification was found in 56% (K-ras and c-myc), 67% (c-fos), and 100% (H-ras) of glass fiber-transformed cell lines. DNA sequencing analysis revealed that both transition and transversion mutations occurred and were concentrated in exon 2 of K-ras and exon 4 of p53. In addition, multiple mutations in different codons were found in K-ras and p53 These results suggest that (1) glass fiber-induced cell transformation could be attributed to the activation of the H-ras, K-ras, c-myc, and c-fos proto-oncogenes and/or the inactivation of the p53 tumor suppressor gene by gene amplification and/or point mutations and (2) multiple mutations might be due to genomic instability resulting from chromosomal alterations induced by glass fibers.

3T3 Cells↗
PubMed1979

Effect of styrene and fiber glass on small airways of mice.

Three groups of 20 mice each were exposed to respirable glass fibers, to 300 ppm styrene vapor, and to glass fibers plus 300 ppm styrene. The glass fiber concentration was congruent to 1070/cm3; fiber diameters were under 3 micron and fiber lenths under 10 microns. The 5 h/d, 5 d/wk inhalation experiment lasted 6 wk. Glass fibers did not cause any lung damage when inhaled separately but combined styrene and glass fibers induced a change in the cellularity of the bronchiolar lining, where aprocrine-type cells became predominant. The same type of bronchiolar epithelial change was found in 10% of the styrene-exposed mice, while most of the styrene-exposed animals (90%) presented thickened bronchiolar walls becasue of stratification of the bronchiolar epithelium.

Aerosols↗
PubMed1983

Deposition of Crocidolite asbestos and glass microfibers inhaled by the Beagle dog.

The respiratory tract deposition of neutron activated Crocidolite asbestos and glass microfibers was determined in two groups of four Beagle dogs. The dogs were given 60-minute, nose-only inhalation exposures to an aerosol of either asbestos or glass fibers. The radioactivity in tissues and excreta four days after exposure was used to determine the fraction of inhaled fibers deposited in the upper respiratory tract and the deep lung. The activity median aerodynamic diameter (AMAD), count median diameter (CMD) and count median length (CML) were determined from fibers sampled during exposure. Crocidolite asbestos fibers (obtained from the Union Internationale Contre le Cancer) had an AMAD of 1.8 microns, a CMD of 0.25 micron and a CML less than 5 microns. The fraction of inhaled mass deposited in deep lung was 13-19 percent, while total deposition in the respiratory tract was 54-72 percent. Glass microfibers had an AMAD of 2.5 microns, a CMD of 0.15 microns and a CML of 5.4 microns. Five to 17 percent of the mass of glass fiber was deposited in the deep lung; total respiratory tract deposition was 45-64 percent. The deposition patterns were similar for these small asbestos and glass fibers inhaled by dogs and in good agreement with previous predictions made for man.

Aerosols↗
PubMed1990

Detection of HIV antibody and antigen (p24) in residual blood on needles and glass.

There is a significant rate of percutaneous injury with needles during the care of patients with acquired immunodeficiency syndrome (AIDS). Following puncture injury, it is recommended that the source of the contaminating blood be checked, and if human immunodeficiency virus-type 1- (HIV-1)-seropositive, zidovudine prophylaxis be considered. As the source of contaminating blood may be unknown, we studied the detectability of HIV-1 antibody and circulating antigen (p24) in the residual blood from needles and pieces of glass at various intervals following exposure to blood. The residual volume of blood remaining in needles varied from 183 +/- 50 microliters for a 20 G needle to 7.8 +/- 1 microliter for a 27 G needle, and the residual blood on small pieces of glass varied from 23 microliters for a piece weighing 558 mg to 2 microliters for a piece weighing 21 mg. Analysis of washed samples of residual blood from all 20 G through 26 G needles and from broken pieces of glass larger than 0.41 g that had been exposed to HIV-1-seropositive blood and left at room temperature for one hour, one day and one week resulted in positive tests for HIV-1 antibody by enzyme-linked immunosorbent assay (ELISA), immunofluorescence and Western blot assays. The circulating antigen was detected in residual blood of 20 G through 26 G needles, but not from contaminated pieces of glass. This technique could be applied to situations where a healthcare worker pricked him- or herself with a needle or with a piece of glass that had been contaminated with blood of unknown seroreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗
PubMed2000

Effects of glass and backscatter on measurement of absorbed dose in polyacrylamide gel (PAG) dosimeters.

Different methodologies are used for calibrating polyacrylamide gel (PAG) dosimeters. One methodology involves injecting nitrogen-filled glass vials with polymer gel. Due to the vials being pre-filled with nitrogen, a nitrogen-filled space remains in the glass vial above the gel. The glass vial is then irradiated using ionizing radiation to polymerize the PAG. Monte Carlo simulations were performed to examine the effects on the radiation field due to the glass vial and the lack of backscatter material due to the nitrogen-filled space. Results for two different formulations of PAG indicated that the influence of the glass and the nitrogen-filled space are negligible.

Acrylic Resins↗
PubMed2006

Effects of Er:YAG laser on the sealing of glass ionomer cement restorations of bacterial artificial root caries.

OBJECTIVE: The aim of this study was to test the effect of Er:YAG laser irradiation on the marginal sealing of root cavities restored with two glass ionomer cements. BACKGROUND DATA: For preventing secondary root caries, new technologies for dental caries removal, such as the Er:YAG laser irradiation, have been proposed. METHODS: Forty-five human teeth were used. Artificial root caries were induced using a microbiological model (Streptococcus mutans). The lesions were removed by three different methods: conventional technique using burs (controls; groups 1 and 2); Er:YAG laser irradiation using dentine preparation parameters (250 mJ, 4 Hz, 80.6 J/cm2; groups 3 and 4); irradiation with the dentine preparation parameters followed by surface conditioning parameters (60 mJ, 2 Hz, 19.2 J/cm2; groups 6 and 7). After each preparation method, three teeth were prepared for scanning electron microscopy morphological observation. The remaining teeth were restored by conventional glass ionomer cement (G1, G3, and G5) or resin modified glass ionomer cement (G2, G4, and G6). After restoration, the samples were thermocycled (1,000 cycles) and prepared for microleakage test. RESULTS: Scores of less infiltrated samples were observed in groups treated by Er:YAG laser, and the smallest infiltration occurred in the group treated by the dentine preparation parameter, followed by cavity restoration with resin-modified glass ionomer (p < 0.05). CONCLUSION: Our results suggest that root caries removal by Er:YAG laser irradiation, followed by restoration with resin-modified glass ionomer cement, is a suitable choice for dental root caries restoration.

Dental Caries↗
PubMed1977

Comparative recoveries of chlamydia from urethral specimens using glass vials and plastic microtiter plates.

Urethral specimens known to contain Chlamydia were stored at -70 C in transport medium (2SP). For the test, circular glass coverslips were placed in the bottom of each culture vessel (glass shell vials and plastic microtiters plates [5 by 15 cm]) and seeded with McCoy's cells in medium containing 5-iodo-2-deoxyuridine. After 72 hours, cultures were inoculated with the specimens, and after 72 additional hours the monolayers on the coverslips were stained with iodine. Of 43 specimens, Chlamydia was recovered from 29 in glass vials but only from three in plastic plates (P less than .001). Chlamydia isolates could be passed serially only by vial-to-vial transfer; losses of 1,800 inclusion-forming units occurred after one subpassage from plates to either vials or plates. The extents of inactivation at 36 C of Chlamydia suspended in medium and placed in plastic plates and in glass vials were similar after seven hours. A substance toxic for Chlamydia could not be demonstrated in the plastic plates. Any new system for isolating Chlamydia from clinical specimens should be evaluated by comparison with culturing in glass vials.

Chlamydia↗
PubMed2004

Glass recycling in the labour suite is environmentally sound and economical.

BACKGROUND: Glass bottles are used for the storage of local anaesthetics in the US and are recyclable. Recycling would result in hospital solid waste reduction. METHODS: The members of the Department of Anaesthesia were surveyed to determine where these local anaesthetic bottles were disposed of. From November 2002 to April 2003, glass bottles used on the labour and delivery suite were saved for recycling. The number of bottles and the weight recycled were recorded. The number of procedures involving anaesthesia were also recorded during this time period. RESULTS: Residents dispose of the local anaesthetic bottle in the sharps container while consultants dispose of them in the trash (P<0.05). Both means of disposal are not recycled in the US. The average amount of glass recycled per month was 19.37 (3.15) kg. Our hospital pays $0.46/kg (0.26 UK pound/kg) for sharps disposal. By not disposing of the glass in the sharps container, the average savings per month was $8.95 (1.45) (5.15 UK pounds (0.84)). CONCLUSION: The recycling of glass is good for the environment through waste reduction and results in small savings to the hospital.

Anesthesia, Obstetrical↗
PubMed2001

Attachment of benzaldehyde-modified oligodeoxynucleotide probes to semicarbazide-coated glass.

Attachment of oligodeoxynucleotides (ODNs) containing benzaldehyde (BAL) groups to semicarbazide-coated glass (SC-glass) slides is described. 5'-BAL-ODNs are prepared using automated DNA synthesis and an acetal-protected BAL phosphoramidite reagent. The hydrophobic protecting group simplifies purification of BAL-ODNs by reverse phase HPLC and is easily removed using standard acid treatment. The electrophilic BAL-ODNs are stable in solution, but react specifically with semicarbazide groups to give semicarbazone bonds. Glass slides were treated with a semicarbazide silane to give SC-glass. BAL-ODNs are coupled to the SC-glass surface by a simple one-step procedure that allows rapid, efficient and stable attachment. Hand-spotted arrays of BAL-ODNs were prepared to evaluate loading density and hybridization properties of immobilized probes. Hybridization to radiolabeled target strands shows that at least 30% of the coupled ODNs were available for hybridization at maximum immobilization density. The array was used to probe single nucleotide polymorphisms in synthetic DNA targets, and PCR products were correctly genotyped using the same macroarray. Application of this chemistry to manufacturing of DNA microarrays for sequence analysis is discussed.

Benzaldehydes↗
PubMed2004

Construction of oligonucleotide arrays on a glass surface using a heterobifunctional reagent, N-(2-trifluoroethanesulfonatoethyl)-N-(methyl)-triethoxysilylpropyl-3-amine (NTMTA).

A rapid method for construction of oligonucleotide arrays on a glass surface, using a novel heterobifunctional reagent, N-(2-trifluoroethanesulfonatoethyl)-N-(methyl)-triethoxysilylpropyl-3-amine (NTMTA), has been described. The heterobifunctional reagent, NTMTA, carries two different thermoreactive groups. The triethoxysilyl group on one end is specific towards silanol functions on the virgin glass surface, while the trifluoroethanesulfonyl (tresyl) group on the other end of the reagent reacts specifically with aminoalkyl- or mercaptoalkyl- functionalized oligonucleotides. Immobilization of oligonucleotides on a glass surface has been realized via two routes. In the first one (A), 5'- aminoalkyl- or mercaptoalkyl-functionalized oligonucleotides were allowed to react with NTMTA to form a oligonucleotide-triethoxysilyl conjugate which, in a subsequent reaction with unmodified (virgin) glass microslide, results in surface-bound oligonucleotides. In the second route (B), the NTMTA reagent reacts first with a glass microslide whereby it generates trifluoroethanesulfonate ester functions on it, which in a subsequent step react with 5'-aminoalkyl or mercaptoalkyl oligonucleotides to generate support-bound oligonucleotides. Subsequently, the oligonucleotide arrays prepared by both routes were analyzed by hybridization experiments with complementary oligonucleotides. The constructed microarrays were successfully used in single and multiple nucleotide mismatch detection by hybridizing these with fluorescein-labeled complementary oligonucleotides. Further more, the proposed method was compared with the existing methods with respect to immobilization efficiency of oligonucleotides.

Base Pair Mismatch↗
PubMed1976

Enzyme-linked sandwich immunoassay of ornithine delta-aminotransferase from rat liver using antibody-coupled glass rods as solid phase.

A macromolecular antigen, ornithine delta-aminotransferase [EC 2.6.1.13] from rat liver (OAT) was assayed by the sandwich procedure using rabbit (anti-OAT) Fab'-beta-D-galactosidase complex and rabbit (anti-OAT) IgG-coupled glass rods as a solid phase. The Fab' fragments of the rabbit (anti-OAT) IgG were conjugated with beta-D-galactosidase [EC 3.2.1.23] from Escherichia coli using N, N'-o-phenylenedimaleimide. The rabbit (anti-OAT) IgG was coupled to the aminoalkylsilyl glass rods using glutaraldehyde. The rabbit (anti-OAT) IgG-coupled glass rods were incubated with OAT and then with the rabbit (anti-OAT) Fab'-beta-D-galactosidase complex. The amount of OAT was determined from the activity of beta-D-galactosidase bound to the glass rods. A minimum of 0.03 fmoles of OAT could be determined by this method and use of the glass rods gave greater reproducibility, and was more sensitive and simpler than use of Sepharose 4B.

Animals↗
PubMed2004

Coloured glasses for high dose dosimetry using the thermoluminescent technique.

Coloured glasses produced commercially by Cebracê, São Paulo, were analysed by the thermoluminescent (TL) method, to verify the possibility of their use as high-dose dosemeters or irradiation indicators in industrial areas, due to their easy handling and their low cost. The samples were exposed to different radiation doses, using the Gamma-Cell 220 system (60Co) of IPEN. The TL emission curves presented main peaks at 135, 150 and 145 degrees C in the bronze, brown and green glass samples, respectively. Calibration curves were obtained for the glasses between 50 Gy and 360 kGy. Reproducibility of TL response and the lower detection doses were determined for each kind of glass. All tested glasses showed their usefulness as irradiation indicators and as high-dose dosemeters.

Calibration↗
PubMed1985

A single fatal penetrating chest wound from shattered wind-blown glass.

The great majority of penetrating wounds of the thorax result from firearms and bladed weapons. Penetrating wounds of the heart and of the great vessels still have a high immediate mortality. While penetrating chest wounds occasionally result from fragments of glass; most severe and fatal wounds from glass result from one's falling into or through architectural (plate) glass, sustaining wounds of abdomen or extremities, or both. A single, fatal penetrating chest wound resulting from a wind-blown fragment of glass is distinctly uncommon. The unique case of this type reported herein is that of a 12-year-old youth who was struck in his home in the left anterior chest by a single, sharp, slender fragment of glass blown from a window which shattered in a thunderstorm. This resulted in a rapidly fatal penetrating wound involving thoracic viscera. The forensic pathologist must thoroughly investigate and document such accidental deaths, modifying his/her autopsy procedure as necessary for these purposes and to avoid accidental injury at the autopsy table.

Child↗
PubMed1989

Glass ampules and associated hazards.

Accessing drugs dispensed in glass ampules is always associated with glass fragment contamination of the ampule contents on opening. In this study, the glass fragment contamination from the external surface of the ampule occurred 60% of the time with 1-ml sized ampules (p less than .01). Glass contamination has been shown to increase with larger ampule size. The glass ampule poses a potential source of microbial infection to the patient, as well as other hazards to the user. Increased precautions and improved drug container design appear to be desirable.

Drug Contamination↗
PubMed1984

Tritium distribution and excretion following intratracheal instillation of glass microballoon fragments in rats.

The distribution and time course for tritium activity in Sprague-Dawley rats exposed to tritiated glass fragments by intratracheal instillation have been defined. Particles were deposited primarily in the pulmonary region, allowing for the measurement of long-term tritium dissolution and particle movement. The tritium activity of the body water and tissues was found to follow a three-compartment model where tritiated glass fragments provide a continuous input to the body water, and tritium was removed from the body according to the classical elimination pattern for HTO. The dissolution of tritium in vivo was found to be biphasic with exponential function half-times of 6.3 +/- 0.5 and 43 +/- 3 days, respectively. The glass fragments were removed from the pulmonary region slowly, with a half-time of 150 +/- 30 days. The resultant dose to the lung was three orders of magnitude greater than the dose to the body, and approx. 40 times greater than the dose incurred in the lung from the inhalation of a similar quantity of HTO. A theoretical urine tritium time course for the inhalation of glass fragments was found to resemble the typical HTO patterns for several months post-exposure. The similarity of tritiated glass and HTO urine activity will make the determination of the type of exposure difficult.

Accidents, Occupational↗