نتایج جستجو برای: fluorine
تعداد نتایج: 7204 فیلتر نتایج به سال:
This paper studies how boron transient enhanced diffusion (TED) and boron thermal diffusion in Si1 Ge are influenced by a high-energy fluorine implant at a dose in the range 5 10 14 cm 2 to 1 10 cm . Secondary ion mass spectroscopy (SIMS) profiles of boron marker layers are presented for different fluorine doses and compared with fluorine SIMS profiles and transmission electron microscopy (TEM)...
The fluoroacetate-producing bacterium Streptomyces cattleya has evolved a fluoroacetyl-CoA thioesterase (FlK) that exhibits a remarkably high level of discrimination for its cognate substrate compared to the cellularly abundant analogue acetyl-CoA, which differs only by the absence of the fluorine substitution. A major determinant of FlK specificity derives from its ability to take advantage of...
To better understand the effects of low-level fluorine in graphene-based sensors, first-principles density functional theory (DFT) with van der Waals dispersion interactions has been employed to investigate the structure and impact of fluorine defects on the electrical properties of single-layer graphene films. The results show that both graphite-2 H and graphene have zero band gaps. When fluor...
mold powders used in the continuous casting of steel contain the harmful caf2 as a main substance developing toxic gases such as sif4 and hf at elevated temperatures. in this study, three samples of i1, i2 and i3, which contained gypsum free portland cement clinker with different percentages of fe2o3 (5.68, 6.83, 8.02 ) and f- (2.09, 1.06, 0), were prepared and their main characteristics were c...
Carbon-fluorine bonds are among the most unreactive functionalities in chemistry. Interest in their activation arises in part from the high global warming potentials of anthropogenic polyfluoroorganic compounds. Conversion to carbon-hydrogen bonds (hydrodefluorination) is the simplest modification of carbon-fluorine bonds, but efficient catalytic hydrodefluorination of perfluoroalkyl groups has...
thermophysical properties of fluorine are interesting because of its applications in different areas of technologyand industry. the computations of thermodynamic properties were performed with the gma equation of stateunder critical conditions. the present work reports calculations of density, volumetric, and thermodynamicproperties of liquid fluorine on extended ranges of pressure and temperat...
PURPOSE Current topics in fluorine research are presented with emphasis on findings by researchers in Szczecin and Poland, as well as in the world. Reports are cited on the distribution of fluorine compounds in the environment, routes of penetration into living organisms, and analytical methods for the quantitative determinations of fluorine content in air, water, soil, and foods. Important con...
Positron emission tomography (PET) is an important driver for present day healthcare. Fluorine-18 is the most widely used radioisotope for PET imaging and a thorough overview of the available radiochemistry methodology is a prerequisite for selection of a synthetic approach for new fluorine-18 labelled PET tracers. These PET tracers can be synthesised either by late-stage radiofluorination, int...
Prolonged administration of a daily dose of 5-10 mg. of fluoride to patients with hyperthyroidism may cause clinical improvement together with a significant fall in the level of plasma protein-bound iodine and a reduction in the basal metabolic rate. Studies with radioactive fluorine failed to demonstrate any important accumulation of fluorine within the thyroid in vivo. Thyroidal, blood and ur...
More than 200 specimens from different occurrences of the Rogaland igneous complex and surrounding granulite facies metamorphic rocks (S. W. Norway) have been analysed by a direct non-destructive proton induced gamma-ray emission (PIGE) technique. The fluorine contents vary from < 25 ppm to 3500 ppm. There is a good correlation between the concentration of fluorine and that of phosphorus for ig...
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