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Abstract  

Commercial light-cured dental composites were used in this study. Two laboratorial composites, Resilab (Wilcos/Brazil), Epricord (Kuraray/Japan) were compared under cured and uncured conditions. Thermal analysis, infrared spectroscopy and scanning electron microscopy were used to evaluate the dental composites. The mass change and heat flow signals (TG–DSC) were recorded simultaneously by using STA 409 PC Luxx (NETZSCH), in the 25–800 °C temperature range at a heating rate of 10 °C/min under nitrogen atmosphere (70 mL/min). Employing thermo-microbalance TG 209 C F1 Iris (NETZSCH) coupled to the BRUKER Optics FTIR TENSOR, the samples were analyzed by combined thermogravimetric and spectroscopic methods (TG–FTIR). The initial sample mass was about ~12 mg, the data collection have been done in the 35–800 °C temperature range at a heating rate of 20 K/min in nitrogen atmosphere (flow rate: 40 mL/min). Finally, superficial topographic was analyzed by scanning electron microscopy (SEM). Dental composite evaluation suggests a high thermal stability and inorganic content in RES D sample. Degrees of conversion (DC) values were almost the same and there was no direct relationship between DC and amount of particles and size. Similar compositions were found in all samples.

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Abstract  

Heavy metals like the actinides possess a high risk potential to the environment not only because of their radiotoxicity but also due to their chemical toxicology. Uranium as one of the major actinide elements has to be considered in particular. Under reducing conditions, tetravalent uranium occurs primarily in the environment. To date, a lack of appropriate analytical techniques that featured sufficient sensitivity made it difficult to study the aqueous phosphate chemistry of uranium(IV) as such complexes show only low solubility. A novel time-resolved laser fluorescence spectroscopy system was set up recently and optimized to do research on uranium(IV). By application of this laser system we could successfully study uranium(IV) phosphate in concentration ranges where no precipitation or formation of colloids occurred. At pH = 1.0, U4+ and one uranium(IV) phosphate complex existed in parallel in aqueous solution. The complex could be identified as [U(H2PO4)]3+. Determination of its corresponding complex formation constant via two different evaluation methods resulted in the finding of (1)
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\log \beta_{121}^{ \circ } = 2 6. 3 7 \pm 0. 7 6$$ \end{document}
and (2)
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\log \beta_{121}^{ \circ } = 2 6. 4 3 \pm 0. 2 3$$ \end{document}
. Both values prove that [U(H2PO4)]3+ is a very stable complex in solution under experimental conditions. As they are in very good agreement with each other, the total complex formation constant was determined by means of the weighted average out of (1) and (2). It was calculated to be
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\log \beta_{121}^{ \circ } = 2 6. 4 2 \pm 0. 2 2$$ \end{document}
.
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elemental analysis as input data, which requires expensive chromatographic analysis [ 13 ]. However, Fourier transform infrared (FTIR) spectroscopy, either mid-IR (MIR) or near-IR (NIR), are among the most trusted analytical techniques in monitoring

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Abstract  

For the positional isotopic analysis of tritium-labelled organic compounds which are isolated at the end of a tracer experiment, it is proposed to render high-resolution triton-NMR spectroscopy sufficiently sensitive as follows. Andrew's rotating magnetic field is used to narrow the NMR lines that are detected by observing the anisotropy of the β-radiation of the sample which is kept at 0.01 °K by a helium-dilution refrigerator. In this context, the usefulness of the rotating magnetic field for cryogenic proton-NMR spectroscopy is pointed out.

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UV-cured (ultra violet), water-based and epoxyphenolic lacquers have been characterized as coatings for possible application in vegetable canning industry. These lacquers were applied to three different types of tinplates and tin free steel (TFS). The behaviour of lacquers was monitored applying porosity, flexibility and infrared (IR) reflectance spectroscopy tests. With IR reflectance spectroscopy test, we were able to determine the composition of lacquers. Using porosity and flexibility tests, performed by electrochemical methods, it was possible to characterize the best lacquer for food canning. In this work the variables involved in lacquering, e.g. the weight of coating and the degree of polymerization of lacquers were also taken into account.

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useful in controlling quality changes in food during processing and in storage [ 10 , 11 ]. IR spectroscopy, on the other hand, serves as an established method to determine types and number of chemical bonds present in a sample and therefore it can be

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Abstract  

Instrumental neutron activation, atomic absorption spectroscopy and conventional methods of analysis were used on eight different silicate rocks and two minerals. Trace elements and major constituents were determined. It was considered that the methods should be regarded as complementary analytical techniques.

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Summary  

Temperature induced magnetic phase transition in the interstitial compound LaFe11.6Si1.4C0.2 was studied by zero-field Mössbauer spectroscopy. A paramagnetic doublet and a magnetically split sextet co-existed in the zero-field spectra in the temperature region of 213-218 K, and a thermal hysteresis was observed in the heating and cooling cycles. The spectra indicate that the magnetic phase transition induced by temperature is of first order for this sample.

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Abstract  

57Fe Mössbauer spectroscopy was used to study57Fe doped high Tc TlBaCaCuO4.5+y superconductor between 70 and 295 K. Significant anomalous changes in the shape of the Mössbauer spectrum were observed around the Tc /105–120 K/. This experimental fact could be reproduced. Our finding can be associated with structural changes taking place around the Tc in TlBaCaCuO4.5+y superconductor.

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Abstract  

The kinetics of the solid-phase interaction in the system -Fe-CuCl2. 2H2O was studied by means of Mössbauer spectroscopy. It was established that compounds of divalent and trivalent iron were formed by diffusion controlled chemical reactions. The experimental results were described by the Juravlev-Lesohin-Templeman equations and the modified parabolic law for the oxidation of metals and alloys.

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