Breath water-based doubly labelled water method for the noninvasive determination of CO2 production and energy expenditure in mice

ABSTRACT

We explored a novel doubly labelled water (DLW) method based on breath water (BW-DLW) in mice to determine whole body CO₂ production and energy expenditure noninvasively. The BW-DLW method was compared to the DLW based on blood plasma. Mice (n?=?11, 43.5?±?4.6?g body mass (BM)) were administered orally a single bolus of doubly labelled water (1.2?g H₂¹⁸O kg BM^?1 and 0.4?g ²H₂O kg BM^?1, 99 atom% (AP) ¹⁸O or ²H). To sample breath water, the mice were placed into a respiration vessel. The exhaled water vapour was condensed in a cold-trap. The isotope enrichments of breath water were compared with plasma samples. The ²H/¹H and ¹⁸O/¹⁶O isotope ratios were measured by means of isotope ratio mass spectrometry. The CO₂ production (RCO₂) was calculated from the ²H and ¹⁸O enrichments in breath water and plasma over 5 days. The isotope enrichments of breath water vs. plasma were correlated (R²?=?0.89 for ²H and 0.95 for ¹⁸O) linearly. The RCO₂ determined based on breath water and plasma was not different (113.2?±?12.7 vs. 111.4?±?11.0?mmol?d^–1), respectively. In conclusion, the novel BW-DLW method is appropriate to obtain reliable estimates of RCO₂ avoiding blood sampling.     

Ein Beitrag zur Bestimmung des Jodgehaltes der Luft

Zusammenfassung Es wird eine vereinfachte Bestimmung des Jodgehaltes der Luft angegeben, wobei die Luft durch eine Pottaschelösung gesaugt und dieser nach dem Einengen mittels Alkohol in der Wärme das gebildete Kaliumjodid entzogen wird. Der Verdunstungsrückstand des klarfiltrierten Alkohols wird nachWinkler titriert. In Graz und Umgebung wurden 24 orientierende Bestimmungen durchgeführt, wobei die geringsten Werte am Boden (0,5/m³) und die höchsten auf den Bergen (1200 m mit etwa 3/m³) gefunden wurden.

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Summary A simplified method of determining the iodine content of air is described, in which the air is drawn through a potash solution; the resulting potassium iodide is then extracted from this solution, after concentration, by means of warm alcohol. The alcoholic extract is clarified by filtration and evaporated to dryness. The iodide content is determined by theWinkler method. Twenty four orienting determinations were carried out in Graz and its environs. The lowest value (0.5/m³) was found on the ground level and the highest (3/m³) on the mountains (1200 m).

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Résumé On donne un dosage simplifié pour la teneur en iode dans l'atmosphère, dans lequel l'air est aspiré à travers une solution de potasse et l'on épuise l'iodure de potassium formé après concentration à chaud avec l'alcool. Le résidu de l'évaporation de la solution alcoolique limpide est titré par la méthode deWinkler. A Graz et dans les environs, on a effectué 24 dosages bien répartis de telle sorte que les valeurs les plus faibles (0,5/m³) ont été trouvées au ras du sol et les plus fortes en montagne (environ 3/m³ à 1200 m).

     

Investigation of thermal and dielectric properties of tin-doped piezoelectric ceramics based on barium titanate

The temperature dependences of the permittivity and pyroelectric coefficient of BaTi_{1 − x} Sn _x O₃ piezoelectric ceramics with a homogeneous composition and a tin concentration gradient have been studied. The thermal diffusion coefficient has been measured. The polarization profiles of the materials under study have been calculated by the thermal square wave method at a single frequency.     

Similarity-transformed chiral NN + 3N interactions for the ab initio description of 12C and 16O

We present first ab initio no-core shell model (NCSM) calculations using similarity renormalization group (SRG) transformed chiral two-nucleon (NN) plus three-nucleon (3N) interactions for nuclei throughout the p-shell, particularly (12)C and (16)O. By introducing an adaptive importance truncation for the NCSM model space and an efficient JT-coupling scheme for the 3N matrix elements, we are able to surpass previous NCSM studies including 3N interactions. We present ground and excited states in (12)C and (16)O for model spaces up to N(max) = 12 including full 3N interactions. We analyze the contributions of induced and initial 3N interactions and probe induced 4N terms through the sensitivity of the energies on the SRG flow parameter. Unlike for light p-shell nuclei, SRG-induced 4N contributions originating from the long-range two-pion terms of the chiral 3N interaction are sizable in (12)C and (16)O.     

Absorption and scattering of light by Pt, Pd, Ag, and Au nanodisks: absolute cross sections and branching ratios

Localized surface plasmons (LSPs) of metallic nanoparticles decay either radiatively or via an electron-hole pair cascade. In this work, the authors have experimentally and theoretically explored the branching ratio of the radiative and nonradiative LSP decay channels for nanodisks of Ag, Au, Pt, and Pd, with diameters D ranging from 38 to 530 nm and height h=20 nm, supported on a fused silica substrate. The branching ratio for the two plasmon decay channels was obtained by measuring the absorption and scattering cross sections as a function of photon energy. The former was obtained from measured extinction and scattering coefficients, using an integrating sphere detector combined with particle density measurements obtained from scanning electron microscopy images of the nanoparticles. Partly angle-resolved measurements of the scattered light allowed the authors to clearly identify contributions from dipolar and higher plasmonic modes to the extinction, scattering, and absorption cross sections. Based on these experiments they find that absorption dominates the total scattering cross section in all the examined cases for small metallic nanodisks (D<100 nm). For D>100 nm absorption still dominates for Pt and Pd nanodisks, while scattering dominates for Au and Ag. A theoretical approach, where the metal disks are approximated as oblate spheroids, is used to account for the trends in the measured cross sections. The field problem is solved in the electrostatic limit. The spheroid is treated as an induced dipole for which the dipolar polarizability is calculated based on spheroid geometry and the (bulk) dielectric response function of the metal the spheroid consists of and the dielectric medium surrounding it. One might expect this model to be inappropriate for disks with D>100 nm since effects due to the retardation of the incoming field across the metallic nanodisk and contributions from higher plasmonic modes are neglected. However, this model describes quite well the energy dependence of the dipolar resonance, the full width at half maximum, and the total extinction cross section for all four metallic systems, even when 100相似文献   

Low-temperature specific heat of Sr<Subscript>2</Subscript>RuO<Subscript>4</Subscript>

We report low-temperature measurements 0.07 K ? T ? 2 K of the specific heat, C, of the perovskite superconductor Sr₂RuO₄. Based on a detailed analysis of our data with respect to both sample quality (as measured by T _c = 0.43 K - 1.17 K) and magnetic-field dependence, it is shown that the electronic contribution to the specific heat, which contains the desired information on the gap structure, is superimposed by at least two additional contributions: a Schottky-type hump at T ≈ 0.1 - 0.2 K and a low-temperature upturn in C / T at T < 0.1 K. We discuss possible origins of these additional contributions and their implications for the interpretation of low-temperature C ( T ) data. Received 23 August 2001     

Über die Verwendung von anorganischen „Quasi-Matrizen-Gelen“ zur Fraktionierung in Hochpolymeren

Colloid and Polymer Science - Aus der Herstellungstechnik von Katalysatorträgern ist bekannt, daß sich Kieselgele durch Zusatz von löslichen Polymeren, z. B. Polyvinylalkohol, bei...     

Effect of temperature on the polarization distribution in BTS functional gradient ceramics

The effect of the chemical composition gradient in barium titanate-stannate (BTS) piezoelectric ceramic on the depth distribution of the effective pyroelectric coefficient was investigated. A correlation between the coordinate dependence of polarization in the sample and the polarization temperature is demonstrated.