Protein measurement with the Folin phenol reagent.
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Molybdenum↗
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Determination of cerebrospinal fluid protein with the Folin phenol reagent.
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Cerebrospinal Fluid Proteins↗
Photodegradation of hydrophobic disperse dyes and dye-bath effluents by silicadodecatungstate (SiW12O40(4-/5-)) nanoparticles.
Polyoxometalate (POM) silicadodecatungstic acid has been applied as a photochemical catalyst for the degradation of SETAPERS Black WNSP, a disperse dyestuff preparation widely used to dye polyester and polyamide fabrics. It could be demonstrated that the disperse dyestuff was photo-reduced by SiW12O40(5-), the one-electron reduced form of POM, as evidenced by Heteropolyblue (HPB) formation. For completion of the photochemical redox cycle, isopropanol (IsOH) was required. Acetone (Ac) served solely as an effective solute and photosensitizer; however this effect was suppressed in the presence of POM. Threshold (0.087 mM) and optimum (0.375 mM) POM concentrations existed and decolorization kinetics were inhibited upon the addition of dye auxiliary chemicals. Increasing the dyestuff concentration from 50 mg/L to 150 mg/L did not affect initial decolorization kinetics revealing that not the formation of the excited [POM-Substrate]* complex, but its reduction to HPB was the rate limiting step. POM-mediated, IsOH-assisted UV-photodegradation of disperse dyes and dye-baths is by far more effective than applying other, more well known chemical oxidation methods (O3, H202/UV, Power Ultrasound). Key to the action of POM redox catalysts is the feature that particularly heteropoly tungstates undergo facile re-oxidation to their original state, thus allowing regeneration of the photocatalyst, a feature that may become critical for real-scale application.
Catalysis↗
Finishing and polishing of indirect composite and ceramic inlays in-vivo: occlusal surfaces.
This study evaluated occlusal margins and surfaces of composite and ceramic inlays after finishing and polishing in vivo. Eighty Class II cavities surrounded by enamel were prepared by two experienced dentists. Forty cavities were restored with indirect microhybrid composite inlays (Tetric), the balance were treated with heat-pressed glass ceramic inlays (IPS Empress). Using a rubber dam, the inlays were inserted adhesively with a dual curing composite of high viscosity (Variolink Ultra). Finishing was performed with the sequence of a 30 microm and 20 microm diamond (finishing method FM 1) or a 30 microm diamond followed by a tungsten carbide finishing bur (FM 2). The composite inlays were divided into four groups of 10 that were finished and polished according to the following protocol: (A) FM 2/Diafix-oral, (B) FM 2/MPS gel, (C) FM 1/Diafix-oral, (D) FM 1/MPS gel. Ten ceramic inlays each were treated as follows: (E) FM 2/MPS gel, (F) FM 1/MPS gel, (G) FM 2/ Diamond polisher, (H) FM 1/Ceramiste silicon polishers. After polishing, replicas of the restorations were fabricated. The replicas were examined by SEM with respect to margin quality (portion of continuous margins, overhangs, submargination and marginal imperfections). Furthermore, surface properties were evaluated qualitatively, which included assessing roundness of the contours in three grades (smooth rounding, few edged contours or predominantly edged contours) and evaluation of the surface roughness (smooth and homogeneous surface, minor roughness or severe roughness). Quantitative analysis of the occlusal composite and ceramic inlay margins showed that 52.2%-84.6% were rated as continuous, 0%-14.0% were characterized by overhangs and 0.7%-10.8% by submargination. A portion of 4.9%-18.1% margins revealed imperfections. The amount of marginal gap formation was negligible. Composite and ceramic inlays showed a similar behavior with respect to marginal quality after finishing and polishing. Overall, there were no significant differences among the four methods applied to composite and the four methods used on ceramic inlays with respect to margin quality. The use of a 30 microm diamond followed by a tungsten carbide bur on composite and ceramic inlays resulted in a significantly larger portion of continuous margins compared to finishing with two diamonds (p=0.049). Qualitative evaluation of composite and ceramic inlays revealed that 50%-80% of the occlusal surfaces were characterized by few edged contours and 10%-50% by smooth rounding. With respect to roughness, smooth surfaces prevailed both on composite (67.5%-80.0%) and ceramic inlays (64.5%-77.3%). Overall, no significant differences were detectable between the methods for finishing and polishing composite inlays and the methods applied to ceramic restorations with respect to roundness of contours and surface roughness.
Adolescent↗
[Method for determination research of trace germanium in the serum of cancer patients by graphite furnace atomic absorption spectrometry].
Using a tungstate-coated graphite tube, trace germanium in serum samples was determined by Zeeman graphite AAS with NH4NO3 as a matrix modifier. The sensitivity of Ge can be significantly improved. The matrix interference has been removed. The relative standard deviation is less than 3.61%. The method is simple, rapid and accurate.
Blood Chemical Analysis↗
[Heat propagation in dentin during cavity preparation in vitro with oscillating instruments].
The purpose of this work was to study the temperature rise caused by preparation of human dentin using two different types of oscillating instruments. A newly designed tungsten carbide tip (Cariex TC, KaVo) and a diamond-coated tip (Cariex D, KaVo) in combination with an airscaler (Sonicflex 2003L, KaVo) and two different flow rates of two coolants were investigated. For both tips significant differences in temperature rise were found between cooling with waterspray or with Plakout Gel (Kerr, HaWe) and using no coolant. A flow of 7.3 ml water/min was found to be sufficient to avoid any critical temperature rise, an excavation of longer duration without coolant cannot be recommended. The use of water-based highly viscous substances over a defined period during the caries excavation process seems to be a viable alternative.
Dental Caries↗
Buyers' guide to diamonds and burs. So, what's new in burs?
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Catalogs, Commercial as Topic↗
The protein-protein complex between pp60v-src and hsp90 is stabilized by molybdate, vanadate, tungstate, and an endogenous cytosolic metal.
In a recent study demonstrating the cell-free reconstitution of the pp60v-src-hsp90 complex, we found that the tyrosine kinase-hsp90 complex is stabilized by molybdate (Hutchison, K. A., Brott, B. K., De Leon, J. H., Perdew, G. H., Jove, R., and Pratt, W. B. (1992) J. Biol. Chem. 267, 2902-2908). In this paper, we examine in detail the stabilization of this protein-protein interaction by transition metal oxyanions. The pp60v-src-hsp90 complex is stabilized by sodium molybdate with the same concentration dependence as the glucocorticoid receptor-hsp90 complex. As with the steroid receptor heterocomplexes, vanadate and tungstate also stabilize the pp60v-src-hsp90 interaction. Passage of cytosol through a Chelex-100 metal-chelating resin destabilizes the native pp60v-src-hsp90 complex, suggesting that the complex is normally stabilized by an endogenous metal factor. Readdition of either the heat-stable components of cytosol or a partially purified endogenous metal factor stabilizes the metal-depleted complex. Molybdate also stabilizes the presence of p50, a known hsp90-associated protein, in the pp60v-src heterocomplex. Given the identical effects of transition metal oxyanions on both pp60v-src- and steroid receptor-hsp90 complexes and the lack of any sequence homology between pp60v-src and the receptors, it seems very likely that it is the common component, hsp90, that contains the site of the metal interaction.
Animals↗
Early surface microhardness of a resin composite exposed to a pulse-delayed curing exposure: a comparison of a tungsten halogen and a plasma arc lamp, in vitro.
Surface microhardness numbers of a commercial resin composite have been compared after exposure to a quartz tungsten halogen (QTH) and plasma arc (PAC) lamp respectively, using two exposure protocols. The effect of increased tip-to-composite distance has also been compared. Exposure with the PAC lamp tested is more appropriate to the early finishing of composite restorations after placement and curing than with the QTH. However both lamps were capable of producing comparable surface hardness, with appropriate exposure protocols. The effect of increased tip-to-composite distance was generally not significant between the lamps for continuous exposure.
Acrylic Resins↗
[Effect of rotary instruments on composites for coronal restoration. A proposed evaluation protocol for the effect of rotary instruments and surface conditions].
Numerous core composites are used to reconstruct abutments for fixed partial dentures. The preparation is carried out with various type of burs. The purpose of this study is to facilitate the choice among them. Six chemical composites, one glass ionomer cement and two light cured composites have been selected. Calibrated samples have been made, divided into four series and prepared with six different burs used for fixed partial dentures, three of them as finishing burs. In the first part of the investigation, the samples were examined with a S.E.M., in order to visualize the surface texture. According to the materials used, variations may exist. In the second part of the investigation, a tridimensional study was performed using a mechanical scanner microscope which permitted the quantification of some roughness characteristics, thus, an objective comparison of the surfaces became possible. Due to the complementary nature of the two investigation techniques, a protocol is presented for the study of burs instrumentation and prepared tooth surface.
Carbon↗
Recent developments in human biomonitoring: non-invasive assessment of target tissue dose and effects of pneumotoxic metals.
Tobacco smoke and polluted environments substantially increase the lung burden of pneumotoxic chemicals, particularly pneumotoxic metallic elements. To achieve a better understanding of the early events between exposure to inhaled toxicants and the onset of adverse effects on the lung, the characterization of dose at the target organ would be extremely useful. Exhaled breath condensate (EBC), obtained by cooling exhaled air under conditions of spontaneous breathing, is a novel technique that could provide a non-invasive assessment of pulmonary pathobiology. Considering that EBC is water practically free of interfering solutes, it represents an ideal biological matrix for elemental characterization. Published data show that several toxic metals and trace elements are detectable in EBC, raising the possibility of using this medium to quantify the lung tissue dose of pneumotoxic substances. This novel approach may represent a significant advance over the analysis of alternative media (blood, serum, urine, hair), which are not as reliable (owing to interfering substances in the complex matrix) and reflect systemic rather than lung (target tissue) levels of both toxic metals and essential trace elements. Data obtained among workers occupationally exposed to either hard metals or chromium (VI) and in smokers with or without chronic obstructive pulmonary disease (COPD) are reviewed to show that--together with biomarkers of exposure--EBC also allows the simultaneous quantification of biomarkers of effect directly sampled from the epithelial lining fluid, thus providing novel insights on both kinetic and dynamic aspects of metal toxicology.
Aerosols↗
Re: Effect of resin-removal methods on enamel and shear bond strength of rebonded brackets.
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Dental Bonding↗
Heat generated by residual adhesive removal after debonding of brackets.
AIM: To measure the rise in temperature during mechanical removal of residual adhesive after debonding of brackets in vitro. METHODS: Different carbide burs on a high-speed handpiece were tested. Acrylic on the buccal surfaces of recently extracted human maxillary incisors was removed using 3 types of carbide burs (6-, 12-, 40-fluted) with a varying number of windings relative to the long axis of the shaft. The temperature was measured using a thermocouple probe in the pulp chamber of the extracted teeth. RESULTS: The highest mean rise in temperature was measured using a 6-fluted bur (+9.4 degrees C, P < .001), followed by the 12-fluted bur (+6.5 degrees C, P <.001). The lowest rise in temperature (+1.2 degrees C, not significant) was seen with a 40-fluted bur. After 3 to 8 seconds of continuous grinding, the rise in temperature seems to slow down. CONCLUSION: The removal of residual adhesive after debonding is best performed with fine burs. If 6-fluted burs are used, a pause after 5 to 10 seconds of continuous grinding is recommended, especially in the mandibular anterior area.
Body Temperature↗
Analysis of trypsin inhibitors and lectins in white kidney beans (Phaseolus vulgaris, var. Processor) in a combined method.
Buffered saline extraction, affinity chromatography, and Folin-BSA protein assay were used consecutively to provide a combined method for analysis of trypsin inhibitors and lectins in white kidney beans (Phaseolus vulgaris, var. Processor). The method was tested by following the decrease of both antinutritional factors by germination of the beans for 7 days at 20 degrees C. Repeatability coefficients of variation were 2-7.4% for the trypsin inhibitors and 2.2-10% for the lectins. After 7 days of germination, trypsin inhibitors and lectins were reduced by 72 and 92%, respectively.
Chromatography, Affinity↗
Studies on the antiviral activity of inorganic heteropolyanions against Semliki forest virus in vivo and vaccinia virus in vitro.
Seven new inorganic heteropolyanions were tested for their antiviral activity. One of these, sodium 12-tungstoborate, was found to protect mice from Semliki forest virus and mouse embryo fibroblast monolayers from vaccinia virus infections. In mice these heteropolyanions exhibited no synergistic antiviral activity with the interferon inducing mycoviral double-stranded RNA.
Animals↗
Comparative efficiency testing 330 carbide dental burs utilizing Macor substrate.
Traditionally, it has been difficult to compare the clinical performance of carbide dental burs. The purpose of this laboratory study was to investigate the comparative cutting efficiency of number 330 dental burs from six manufacturers. These burs were tested utilizing custom-built equipment consisting of a frictionless air sled to which the Macor substrate was attached. The substrate was fed to the bur at constant pressure. The efficiency of each bur, defined as the distance of the cut divided by the time taken, then was calculated. Of the six bur types tested, only one was found to be markedly superior, and four types were comparable in performance.
Dental Cavity Preparation↗
[Study of the response characteristics of PVC membrane ion-associate type electrodes for organic base cations].
A new type of ISEs which only uses alkaloid precipitants in place of ion pairs as active materials in polyvinyl chloride was recommended. The characteristics of the electrodes sensing over ten kinds of organic bases have been studied in comparison with those based on ion pairs. It can be concluded that the response characteristics of ion-associate type ISEs depend on the strength of the association between ion-exchange site and principal ions. Visual turbidimetry was used to select active materials for ISEs in advance. Among six alkaloid precipitants (silicotungstic acid, tetraphenyl borate, dipicrylamine, picric acid, picrolonic acid and Reineckate), silicotungstic acid is the most active material for ion-associate type organic base cation ISEs. With it, the sensor has wider Nernst linearity and lower detection limit than some ion pair based ones in literature.
Cations↗
[Behavior of a dental rotary instrument alloy after titanium nitride coating].
A titanium nitride coating has been deposited on steel and tungsten carbide dental rotary instruments. This process is carried out under partial vacuum, by reacting vapourized metal (titanium) and nitrogen in a plasma. The instruments temperature is around 500 degrees C during coating. We have determined by micro-analysis the treatment modifications upon the different bursa components. VICKERS microhardness tests have shown the coating temperature effects towards the heat treatments of employed steels.
Dental High-Speed Equipment↗