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Abstract  

The energy of combustion of crystalline 3,4,5-trimethoxybenzoic acid in oxygen at T=298.15 K was determined to be -4795.91.3 kJ mol-1 using combustion calorimetry. The derived standard molar enthalpies of formation of 3,4,5-trimethoxybenzoic acid in crystalline and gaseous states at T=298.15 K, ΔfHm Θ (cr) and ΔfHm Θ (g), were -852.91.9 and -721.72.0 kJ mol-1, respectively. The reliability of the results obtained was commented upon and compared with literature values.

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Abstract

The degradation of art objects is caused by the combination of all indoor environmental factors. To investigate the deterioration processes in paintings and at the same time to design a risk assessment system, chemical sensors based on artist's materials are developed. Therefore standard paint films of egg yolk tempera with lead white 2PbCO3·Pb(OH)2, azurite 2CuCO3·Cu(OH)2 or smalt were investigated. With accelerated ageing experiments the simulation of natural degradation processes is aimed. First markers for chemical changes were found in the FTIR and TG/DSC measurements.

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Résumé  

Les milieux biologiques étalon pour une analyse élémentaire sont peu nombreux et posent des problèmes d'homogénéité, de conditions reproductibles, de séchage et de stokage. Leur usage a soulevé un certain nombre de problèmes concernant la sureté de certaines techniques analytiques, quelques uns de ces problèmes n'ont toujours pas de solution. Ils sont illustrés en se référant à un échantillon standard de chou, de sang humain, d'hématies et de sérum, lesquels ont été analysés à plusieurs reprises. Des valeurs raisonnablement sures sont maintenant connues pour les 35 éléments suivants dans l'échantillon standard de chou: Al, As, Au, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cs, Cu, F, Fe, Hg, K, La, Mg, Mn, Mo, N, Na, P, Pb, Rb, S, Sb, Sc, Si, Sn, U, V, W, Zn; il reste des incertitudes pour Ag, Ce, Ga, I, Ir, Ni, Se Sm et Ti. Dans le sang, les analyses des 17 éléments suivants sont suffisamment exactes pour permettre l'emploi de ce produit comme un étalon, approximatif. Ba, Br, Ca, Cl, Cu, Fe, I, K, Mg, Na, Ni, P, Pb, Rb, Se et Zn. Cependant il y a de sérieux doutes au sujet de la constante de la concentration de certains de ces éléments selon les individus. A la suite d'une récente étude, l'exactitude des résultats concernant, Ag, As, Co, Cr, F, Hg et Sb est également mise en doute.

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Abstract

This paper discusses the assessment methodology of geologic probabilities of success of drillable prospects determined by petroleum exploration geologists. The commonly accepted industry standard assessment methods suggest the probability evaluation of key components of oil and gas accumulation: source rock, reservoir, seal rock and trap, and migration and timing. On the assumption that the risked events resulting in the assembly of the key components are geologically and eventalgebraically independent, the geological probability is computed as the product of the probabilities of each. Without challenging the overall correctness of the approach, this study argues that the presumed independency does not always apply. For these cases, probability evaluation of the actually and truly independent geologic and hydrodynamic processes is advised.

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Abstract  

Several reference materials and associated reference values have been recommended for the purposes of calibration and/or validation of differential scanning calorimetry (DSC). However, issues of available sample purity, reference-property value accuracy, and potential undesired reactions between reference materials and the materials used for sample pans have not been considered sufficiently in some of the recommendations of property values for the materials. These limitations attenuate greatly the usefulness of many of these reference material recommendations. Indeed, the state of uncertainty regarding true reference property values can be shown to be a limiting factor in the uncertainty of measurements made with DSC. NIST has certified the temperatures and enthalpies of fusion of two new Standard Reference Materials, SRMs 2234 and 2235, in order to help alleviate some of the difficulty.

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Abstract  

In recent years researchers in the Performance Indicators Project at the Australian National University have undertaken a number of projects involving collaboration with colleagues in England or attempts to replicate results obtained by others. All projects have necessitated close scrutiny of the methodologies previously used or to be used and have made clear the urgent need for comparable standards. In this paper we have focused on two projects: one, an analysis of Australia's shares of publications and citations, where we sought to learn from the debate on methodology that surrounded the question of decline in British science; the second, an analysis of astronomy publications in Australia where we sought to replicate methodology used in a previous European study.

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Abstract  

The environmental mobility/availability behavior of radionuclides in soils and sediments depends on their speciation. Experiments have been carried out to develop a simple but robust radionuclide sequential extraction method for identification of radionuclide partitioning in sediments and soils. The sequential extraction protocol was optimized for temperature, concentration of reagents and reaction time. Optimum extraction conditions were chosen based on the release of 239,240Pu, 238U and stable elements. Results from the experiments with lake sediment (SRM 4354) are compared to the previous trials where the sequential extraction protocol was optimized with the ocean sediment (SRM 4357). Based on these two trials the NIST standard sequential extraction protocol is established for defined extraction settings for temperature, reagent concentration and time.

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A differential calorimeter was used to set up and critically evaluate a series of organic substances as temperature standards over the range 50–330°. The conditions for acceptance of a standard substance were a sufficient degree of purity, thermal stability, absence of polymorphism, a suitable cryoscopic constant, low volatility and ready availability.

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the following) targeting the E-gene and the N2-region of the N-gene as the gold standard according to the validation protocol as suggested for laboratory-developed real-time PCR assays by Rabenau and colleagues [ 17, 18 ]. This implies comparative

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Abstract  

Uranium was measured in eight biological standards at the part-per-billion level. Matrix effects encountered in the use of liquid standards are discussed.

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