Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.2.42 (DTA)
 1,693 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cause of the three shrinkages in the thermal expansion curves of gypsum bonded investments, which were characterized in the previous study, was examined mainly by means of TG-DTA method, X-ray diffraction method and SEM observation. The main results were as follows: 1. The first shrinkage between 100 degrees C and 200 degrees C was caused by the dehydration of gypsum. 2. The second shrinkage between 300 degrees C and 400 degrees C was due to the transformation of soluble anhydrite to insoluble anhydrite. 3. The third shrinkage beginning at the temperature range 700 degrees C approximately 800 degrees C is considered to be related to the sintering of insoluble anhydrite.
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PMID:[Thermal behavior of gypsum bonded investments. (Part I) Thermal behavior in heating process(author's transl)]. 29 Jul 8

Circulating microembolic index (CMI) was determined by drawing one blood sample into EDTA-formalin and the other into DTA alone in patients with migraine and compared with matched normal controls. Platelet aggregates, if any, are fixed in EDTA-formalin but disaggregated by EDTA. Ratios of these two counts approximate "unity" in normals and are proportionately less than unity, depending on the number of platelet aggregates. 26 untreated migraineurs and 19 migraineurs with history of self-medication with aspirin taken within 72 hours of the test, were studied in headache-free intervals. Results were compared with those from 20 healthy, age and sex matched volunteers, without migraine, who were medication-free for at least one week. Mean CMI in untreated migraineurs (0.77 +/- 0.03 SEM) was significantly lower than the mean in normal controls (0.94 +/- 0.02, p. less than 0.002). Migraineurs with self administration of aspirin had mean CMI of 0.88 +/- 0.02, differing significantly from untreated migraineurs (p less than 0.01) but not from normal controls (0.1 less than p less than 0.2). Results suggest excessive platelet aggregation in migraineurs which tends to be corrected by treatment with platelet inhibitors such as aspirin.
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PMID:Platelet dysfunction in migraine: effect of self-medication with aspirin. 103 36

Experimental gypsum-bonded investments containing 0.5-5.0 wt% NbC were prepared by mechanical mixing of each powder. Setting and thermal expansion measurement, compressive strength and casting accuracy for Ni-Cr alloy for metal-ceramic restoration were investigated. Analysis of NbC during heating was carried out by X-ray diffraction, TG-DTA and SEM. NbC was oxidized to Nb2O5 with a volume change between 300-600 degrees C, as in the following equation: 2NbC + 4 1/2O2----Nb2O5 + 2CO2 The theoretical volume of 1/2Nb2O5 calculated from the lattice constants according to JCPDS file was approximately 4 times larger than that of NbC. The experimental investments of 70 wt% cristobalite and 30 wt% gypsum containing 2.0, 3.0 and 5.0 wt% NbC showed large thermal expansion of 7.0, 10.0 and 13.0% respectively. The investment containing 2.0 wt% NbC showed nearly the same casting accuracy for Ni-Cr alloys for metal-ceramic restoration as the commercial phosphate-bonded investment.
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PMID:[Application of gypsum-bonded investment containing niobium carbide on casting of alloy for metal-ceramic restoration]. 213 27

In this work we relate about the results coming from crystallographic, physical and mineral tests taken on following biomaterials used in odontostomatology: reabsorbable Dac Blu, non reabsorbable Dac Blu, not reabsorbable atomized Dac Blu, not reabsorbable thin Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-Oss, Biostite, Osprovit, Merck Hydroxiapatite. The data were obtained using the following tests: XRF, XRD, FTIR, TG, DTG, DTA, SEM. The results, although taken on few samples, showed that these biomaterials present a variability in some features, which can define the structural functionality.
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PMID:[The specific characteristics determined by nonbiological tests of mineral-based biomaterials used in dentistry. 7]. 778 13

The crystallization feature of a castable apatite glass-ceramics was studied by the means of DTA, XRD and SEM. The effect of chemical composition on the microsturcture of the glass-ceramics was discussed. The introduction of MgO and Al2O3 into the system has a substantial influence on the crystallization feature.
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PMID:[The crystallization feature of a castable apatite glass-ceramics]. 981 34

Fractured teeth are difficult to treat effectively. Currently, such as root fractures are usually treated by full-coverage restoration, root amputation, or tooth extraction. If the fusion of tooth fracture by laser were possible, it could offer a different therapy to repair fracture teeth. We tried to use a developed DP-bioactive glass paste to fuse or bridge the tooth crack line by a medium energy continuous-wave CO2 laser. The present report was focused on the phase transformation and rescrystallization of DP-bioactive paste during expose to the CO2 laser. The materials will examine by means of XRD, FTIR, DTA/TGA, and SEM. From the study, we could expect that the temperature increase due to laser irradiation must be over than 900 degrees C and the DP-bioactive glass paste could be melted in a short period of time after irradiation. In the study, we successfully developed a DP-bioactive glass paste which could form a melting glass within minutes after exposed to a medium energy density continuous-wave CO2 laser. The paste will be used to bridge the enamel or dentine surface crack by the continuous-wave CO2 laser in the near future.
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PMID:Treatment of dental root fracture by medium energy CO2 laser and DP-bioactive glass paste. Part. II: Compositional, structure, and phase changes of DP-bioglass paste after exposed to CO2 laser. 1114 63

Acute trauma or trauma associated with occlusal disturbance can produce tooth crack or fracture. Although several methods are proposed to treat the defect, however, the prognosis is generally poor. If the fusion of a tooth fracture by laser is possible, it will offer an alternative to extraction or at least serve as an adjunctive treatment in the reconstruction. We have tried to use a continuous-wave CO2 laser and a newly developed DP-bioactive glass paste (DPGP) to fuse or bridge tooth crack or fracture lines. Both the DP-bioactive glass paste and tooth enamel have strong absorption bands at the wavelength of 10.6 microm. Therefore, under CO2 laser, DPGP and enamel should have an effective absorption and melt together. The interface between DPGP and enamel could be regarded as a mixture of DPGP and enamel (DPG-E). The study focused on the phase transformation, microstructure, functional group and thermal behavior of DPG-E with or without CO2 laser irradiation, by the analytical techniques of XRD, FTIR, DTA/TGA, and SEM. The results of XRD showed that the main crystal phase in the DPG-E was dicalcium phosphate dihydrate (CaHPO4.2H2O). It changed into CaHPO4, gamma-Ca2P2O7, beta-Ca2P2O7 and finally alpha-Ca2P2O7 with increasing temperature. In the FTIR analysis, the 720 cm(-1) absorption band ascribed to the P-O-P linkage in pyrophosphate rose up and the intensities of the OH- bands reduced after laser irradiation. In regard to the results of DTA/TGA after irradiation, the weight loss decreased due to the removal of part of absorption water and crystallization water by the CO2 laser. SEM micrographs revealed that the melted masses and the plate-like crystals formed a tight chemical bond between the enamel and DPGP. We expect that DPGP with the help of CO2 laser can be an alternative to the treatment of tooth crack or fracture.
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PMID:Treatment of tooth fracture by medium-energy CO2 laser and DP-bioactive glass paste: the interaction of enamel and DP-bioactive glass paste during irradiation by CO2 laser. 1121 60

The aim of this work was to investigate machinable glass-ceramics used as oral restoration material in K2O-MgO-Al2O3-SiO2-F glass system. By using of DTA, XRD and SEM investigation, the crystalline structure and characteristics were tested. The chemical composition of WCMM machinable glass-ceramics was defined by the following general formula: (K,Na)Mg3-3x Al2x (AlSi3) O10F2(0.5 < or = x < 0.7). The experimental results show that WCMM is an excellent oral restoration materials in the fabrication of crowns, inlayers and veneers.
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PMID:[The preliminary study on WCMM machinable glass-ceramics]. 1147 98

Germanium nanowires, ranging from 10 to 150 nm in diameter, were grown several micrometers in length in cyclohexane heated and pressurized above its critical point. Alkanethiol-protected gold nanocrystals, either 2.5 or 6.5 nm in diameter, were used to seed wire formation. Growth proceeded through a solution-liquid-solid mechanism at growth temperatures ranging from 300 to 450 degrees C. At temperatures exceeding 500 degrees C, large Ge particulates formed due to unfavorable growth kinetics. Temperature, the nature of the precursor, precursor concentration, and the Au:Ge ratio were determining factors in nanowire morphology. The Ge nanowires were characterized using a range of techniques, including XPS, XRD, high-resolution TEM and SEM, nanometer-scale EDS mapping, and DTA.
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PMID:Nucleation and growth of germanium nanowires seeded by organic monolayer-coated gold nanocrystals. 1184 11

Structural evolution upon transformation of sol to gel, and gel to final ceramic during the synthesis of hydroxyapatite is investigated using Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD), thermal behavior (DTA and TGA), and electron microscopy examination (SEM/TEM). The sol was first thermally aged at 45 C for various time periods up to 120 min. The colloidal sol, which may have an oligomeric structure, was relatively stable against coagulation. Upon drying, the sol particles consolidated into dry gel through van der Waals attraction, and showed X-ray amorphous phosphate structure. The solid gels showed a particulate microstructure, composed of primary particles of about 8-10 nm in diameter. The amorphous gel transformed into crystalline apatite at temperatures > 300 C. The calcined gels showed a nano-scale microstructure, with grains of 20-50 nm in diameter. Through an appropriate heat treatment between 300 and 400d degrees C. the apatite prepared using current process exhibits a nano-scale, low-crystallinity, carbonated apatitic structure, which closely resembles that of human bone apatite.
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PMID:Structural evolution of sol-gel-derived hydroxyapatite. 1192 71


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