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21.
Simulation of dual carbon–bromine stable isotope fractionation during 1,2-dibromoethane degradation*
Biao Jin Ivonne Nijenhuis Massimo Rolle 《Isotopes in environmental and health studies》2018,54(4):418-434
We performed a model-based investigation to simultaneously predict the evolution of concentration, as well as stable carbon and bromine isotope fractionation during 1,2-dibromoethane (EDB, ethylene dibromide) transformation in a closed system. The modelling approach considers bond-cleavage mechanisms during different reactions and allows evaluating dual carbon–bromine isotopic signals for chemical and biotic reactions, including aerobic and anaerobic biological transformation, dibromoelimination by Zn(0) and alkaline hydrolysis. The proposed model allowed us to accurately simulate the evolution of concentrations and isotope data observed in a previous laboratory study and to successfully identify different reaction pathways. Furthermore, we illustrated the model capabilities in degradation scenarios involving complex reaction systems. Specifically, we examined (i) the case of sequential multistep transformation of EDB and the isotopic evolution of the parent compound, the intermediate and the reaction product and (ii) the case of parallel competing abiotic pathways of EDB transformation in alkaline solution. 相似文献
22.
As for the commonly studied La0.6Sr0.4Co0.2Fe0.8O3-δ (6428), here, a very low area-specific resistance (ASR) was measured for La0.6Sr0.4Co0.8Fe0.2O3-δ (6482) cathode deposited on a Ce0.9Gd0.1O2-δ (GDC) electrolyte with addition of a thin (1 μm) dense LSCF film deposited by spin coating at the interface between the GDC electrolyte and a 40-μm-thick screen-printed electrode. The ASR ranged from 1 Ω.cm2 at 500 °C, 0.11 Ω.cm2 at 625 °C and value as low as 0.03 Ω.cm2 at 700 °C. Impedance spectra collected in between 500 and 700 °C were carefully studied. They could all be modelled with two R//CPE in series which are likely associated to the oxygen reduction reaction itself (dissociation/adsorption/ionization) at low frequency and to the oxide ion transfer at the electrode/electrolyte interface at high frequency. 相似文献
23.
Zuyuan Wang Konrad Rolle Theresa Schilling Patrick Hummel Alexandra Philipp Bernd A. F. Kopera Anna M. Lechner Markus Retsch Josef Breu George Fytas 《Angewandte Chemie (International ed. in English)》2020,59(3):1286-1294
Controlling thermomechanical anisotropy is important for emerging heat management applications such as thermal interface and electronic packaging materials. Whereas many studies report on thermal transport in anisotropic nanocomposite materials, a fundamental understanding of the interplay between mechanical and thermal properties is missing, due to the lack of measurements of direction‐dependent mechanical properties. In this work, exceptionally coherent and transparent hybrid Bragg stacks made of strictly alternating mica‐type nanosheets (synthetic hectorite) and polymer layers (polyvinylpyrrolidone) were fabricated at large scale. Distinct from ordinary nanocomposites, these stacks display long‐range periodicity, which is tunable down to angstrom precision. A large thermal transport anisotropy (up to 38) is consequently observed, with the high in‐plane thermal conductivity (up to 5.7 W m?1 K?1) exhibiting an effective medium behavior. The unique hybrid material combined with advanced characterization techniques allows correlating the full elastic tensors to the direction‐dependent thermal conductivities. We, therefore, provide a first analysis on how the direction‐dependent Young's and shear moduli influence the flow of heat. 相似文献
24.
Airborne particulate matter (PM) represents one of the most important sources of urban pollution due to its physical and chemical
properties. There is a great concern for PM dangerous effects on human health because particles can deeply penetrate into
the respiratory system, carrying the contaminants adsorbed onto their surface. Polycyclic aromatic hydrocarbons (PAHs) are
a class of organic contaminants that can be adsorbed onto PM and can have harmful effects on health, due to their particular
chemical structure. The International Agency for Research on Cancer (IARC) classified PAHs as potential carcinogenic agents
and benzo[a]pyrene (BaP) as carcinogenic to humans. In this paper, the development of a metrologically traceable procedure for the quantification
of BaP in airborne PM, performed at the Italian National Institute of Metrological Research (Istituto Nazionale di Ricerca
Metrologica—I.N.Ri.M.), is presented. The identification and quantification of BaP in PM samples were carried out by gas chromatography
coupled with mass spectrometry (GC–MS). Metrological traceability was established in all the procedure steps, after performing
the method validation. Suitable certified reference materials (CRMs) were used both to validate the analytical method and
to calibrate the GC–MS. The measurement uncertainty was evaluated by identifying and taking into account all the relevant
sources deriving from the whole procedure steps. 相似文献
25.
Elena Amico di Meane Margherita Plassa Francesca Rolle Michela Sega 《Accreditation and quality assurance》2009,14(11):607-611
Metrologically traceable measurements are needed, in environmental monitoring, to provide meaningful information on the pollution
level and the possibility to have suitable reference standards is crucial to this purpose to calibrate instruments. The Italian
National Institute of Metrological Research (I.N.Ri.M.), as a primary metrological institute, realizes and maintains primary
standards for the basic and derived units of the International System of Units (SI). In this framework and regarding gas analysis,
in the last few years I.N.Ri.M. has started a research line on the preparation of primary reference mixtures (PRMs) by the
gravimetric method that led to plan and build a facility for evacuating and filling cylinders and a device for high precision
weighing. In the present work the developments in such field at I.N.Ri.M. are reported to underline the relevance, in the
atmospheric pollutants monitoring, of performing accurate and reliable measurements and having reference standards fit for
the calibration of the analytical instrumentation. 相似文献
26.
Michela Sega Elena Amico di Meane Francesca Rolle 《Accreditation and quality assurance》2009,14(11):601-605
Metrology in chemistry has its own features, which distinguish it from classical metrology: due to the lack of primary methods
applicable in routine measurements, metrological traceability of measurement results can be achieved by using in a proper
way suitable certified reference materials (CRMs), which can assure a direct relation to a reference. This article deals with
the activity of the Italian National Institute of Metrological Research (Istituto Nazionale di Ricerca Metrologica—I.N.Ri.M.)
on the analysis of various polychlorinated biphenyls congeners in organic solution by means of gas-chromatography coupled
with mass spectrometry. The metrological traceability approach in the quantification step is pursued via calibration solutions
prepared by gravimetrically diluting a CRM. The uncertainty for the calibration solutions was evaluated taking into account
all the relevant contributions. 相似文献