High-precision measurements of δ2H, δ18O and δ17O in water with the aid of cavity ring-down laser spectroscopy

A thorough evaluation of measurement uncertainty together with control of short-term and long-term precision of measurements should be a basis of any successful quality assurance/quality control (QA/QC) strategy aimed at maintaining a high quality of the analytical process. Here we present the results of a comprehensive assessment of the analytical performance of a Picarro L2140-i CRDS laser spectrometer analysing δ²H, δ¹⁸O and δ¹⁷O in water. The assessment is based on results obtained during 15 months of continuous operation of this instrument (February 2017 to May 2018). The short-term precision of measured and derived quantities was 0.11, 0.036, 0.028, 0.23 ‰ and 11 per meg, for δ²H, δ¹⁸O, δ¹⁷O, d-excess and Δ¹⁷O, respectively, and is comparable to the precision reported by the manufacturer. The long-term precision of the L2140-i, defined as standard uncertainty of the time series of 153 analyses of a laboratory standard conducted throughout 15 months, was roughly two times lower (0.24, 0.053, 0.038, 0.37 ‰ and 21 per meg, for δ²H, δ¹⁸O, δ¹⁷O, d-excess and Δ¹⁷O). In-depth assessment of the measurement uncertainty of a single analysis revealed that assigned uncertainty of the calibration standards is an important component of the uncertainty budget, especially in case of δ²H analysis.     

The effect of internal Co2 conductance on leaf carbon isotope ratio

We estimated internal CO₂ conductance (g_i ) for C₃ plant species of different life forms (annual herbs, deciduous trees and evergreen trees) grown in a variety of environments to examine the effect of g i on their leaf carbon isotope ratio (i¹³C). The purpose of this study was to test the validity of using i¹³C as an index of photosynthetic water use efficiency (WUE). When comparing deciduous tree species grown in contrasting light environments, there was a strong positive relationship between i¹³C and WUE. Similarly, i¹³C was positively correlated to WUE when comparing the different species of evergreen trees. However, the difference in WUE between evergreen and deciduous tree species did not relate to that in leaf i¹³C. In addition, WUE was similar between highland and lowland herbaceous plants, although the former had a much higher i¹³C. The positive relationship between i¹³C and WUE did not hold across different life forms and different altitudes when differences in g_i did not relate to those in stomatal conductance, resulting in independence of chloroplast CO₂ partial pressure from intercellular CO₂ partial pressure.     

Accuracy and precision of a laser-spectroscopy approach to the analysis of δ2H and δ18O in human urine

The isotope ratio analysis of body water often involves large sample numbers and lengthy sample processing. Here we demonstrate the ability of isotope ratio infrared spectroscopy (IRIS) to rapidly and accurately analyse the isotope ratios of water in urine. We analysed water extracted from human urine using traditional isotope ratio mass spectrometry (IRMS) and compared those values with IRIS-analysed extracted water and un-extracted urine. Regression analyses for δ²H and δ¹⁸O values between (1) extracted water analysed via IRMS and IRIS and (2) urine and extracted water analysed via IRIS were significant (R ²=0.99). These results indicate that cryogenic distillation of urine was not required for an accurate estimate of the isotopic composition of urine when using IRIS.     

Existence of many ergodic absolutely continuous invariant measures for piecewise-expandingC 2 chaotic transformations in ℝ2 on a fixed number of partitions

Let Ω be a region in ℝⁿ and letp = P_i ) _i ^1m , be a partition ofΩ into a finite number of closed subsets having piecewise C² boundaries of finite(n - 1 )dimensional measure. Let τ:Ω→Ω be piecewise C² onP where, τ_i = τ|p_i is aC ² diffeomorphism onto its image, and expanding in the sense that there exists α > 1 such that for anyi = 1, 2,...,m ‖Dτ_i ^-1 ‖ < α^-1, where Dτ_i ^-1 is the derivative matrixτ _i ^- 1 and |‖·‖ is the Euclidean matrix norm. By means of an example, we will show that the simple bound of one-dimensional dynamics cannot be generalized to higher dimensions. In fact, we will construct a piecewise expanding C² transformation on a fixed partition with a finite number of elements in ℝ², but which has an arbitrarily large number of ergodic, absolutely continuous invariant measures     

Fine structure and isotope shift of the 3s4d 3 D-3s3p 3 P, 3s5d 3 D-3s3p 3 P and 3p 2 3 P-3s3p 3 P Transitions of MgI

Summary We report the measurements of the³ D(3s4d)-³ P(3s3p)³ D(3s5d)-³ P(3s3p), and³ P(3p ²)-³ P(3s3p) transition frequency of MgI, the fine-structure separation and isotope shift between²⁴Mg and²⁶Mg. The measurements have been performed in a metastable atomic beam; a good agreement is found for data already existing in the literature. The accuracy of the measurements reported in this paper is mainly limited by the Doppler broadening of theI ₂ transitions used as a reference and by the precision in the knowledge of the related wavelengths.     

Canopy Gradients in δ18O of Organic Matter as Ecophysiological Tool

Abstract

We determined vertical oxygen isotope gradients of leaf organic matter for a grassland in Switzerland and a mountain beech forest (Fagus sylvatica) in Northern Italy. A distinctly positive ¹⁸O/¹⁶O gradient with height above ground was found for the grassland (7.9‰m^?1, p < 0.001), whereas the gradient was negative for the forest (–0.077‰m^?1, p < 0.001). The results are consistent with microclimatic measurements, although large isotope variations between the species have to be taken into account for the grassland. A conceptual scheme is shown which relates the isotope enrichment to the canopy density, considering the effects of transpiration and canopy structure. We conclude that the analysis of the within canopy variation in δ¹⁸O of organic matter can be used to provide long-term estimates of leaf water isotope composition, thus improving existing isotope methods to determine the gas-exchange between vegetation and atmosphere.     

Yrast bands in N = 91 isotones

The in-beam spectroscopy on N = 91 isotones has been carried out using the ¹²C + ¹⁵⁰Nd reaction. The νi _13/2 and νh _11/2 bands of ¹⁵³Sm have been extended up to 33/2⁺ and 31/2^-, respectively. Two new γ-rays have been located on the top of the unfavored band with νi _13/2 configuration in ¹⁵⁷Dy. Two identical relationships have been established in the low-spin region of the yrast νi _13/2 configuration between ¹⁵³Sm and ¹⁵⁵Gd, and between unfavored bands of ¹⁵⁵Gd and ¹⁵⁷Dy. Here all these nuclei have the same neutron number N = 91. Received: 28 June 2000 / Accepted: 20 October 2000     

Systematic field-theory for the hard-core one-component plasma

A continuous liquid flow in a vacuum (a liquid beam) of an aqueous solution of adenine salt containing hydrochloric acid or sodium hydroxide was irradiated with an intense pulsed IR laser at 3 μm, which is resonant to a vibrational mode related to the OH stretch vibration of H₂O. Neutral species isolated into the vacuum were ionized by a pulsed UV laser at 270 nm, and the product ions were mass-analyzed by a time-of-flight mass spectrometer. It is found that AH ₂ ^{2 + .} 2Cl^- and [A-iH] ^{i - .} iNa⁺ (i = 1-3) are isolated in the vacuum from the aqueous acidic and alkaline solutions, respectively, under irradiation of the IR laser, and undergo four-photon ionization involving decomposition and proton transfer of the intermediate species under irradiation of the UV laser. Received 1st May 2002 Published online 13 September 2002     

Determination of 13CO2/12CO2 Ratio by IRMS and NDIRS

Abstract

Breath tests using ¹³C-labelled substrates require the measurement of ¹³CO₂/¹²CO₂ ratio in breath gas samples. Next to isotope ratio mass spectrometry (IRMS), which is very sensitive but also complex and expensive, alternatively isotope selective nondispersive infrared spectrometry (NDIRS) can be used to determine the ¹³CO₂/¹²CO₂ ratio in expired breath. In this study we compared NDIRS- with IRMS-results to investigate whether the less expensive and very simply to operate NDIRS works as reliable as IRMS. For this purpose we applicated 1-¹³C-Phenylalanine to patients with advanced liver cirrhosis and healthy volunteers and took duplicated breath samples for IRMS and NDIRS at selected time points. Our data show a good correlation between these two methods for a small number of samples as required for simple breath tests. Longer series, where repeated measurements are required on the NDIRS instrument lead to a decreasing correlation. This indicates the superiority of IRMS concerning ¹³CO₂-kinetics over longer time periods.     

Isotope and Hyperfine Structure in the "Orange" System of FeO: Evidence for Two Δi Excited States

The orange system of FeO has been reinvestigated using low-temperature molecular beam laser-induced fluorescence spectra, obtained by supersonic jet cooling. Two new weak bands have been found, and analyses of some of the previously known bands extended. Measurements of the ⁵⁴Fe-⁵⁶Fe isotope shifts have been made for most of the bands, and the hyperfine structure of the low-J lines has been recorded for two of the strongest bands of ⁵⁷FeO. The isotope shifts are consistent with the presence of two ⁵Δ_i-⁵Δ_i transitions lying within 1000 cm⁻¹; the origins of the Ω = 4 spin components lie at 5583 and 6110 Å, respectively. The hyperfine patterns and the spin-orbit structure indicate that the upper state electron configurations are (3dδ)³ (3dπ)² (3dσ)¹, (D⁵Δ_i, 5583 Å) and O(2pπ)³ (4sσ)¹ (3dδ)³(3dπ)³, (D′⁵Δ_i, 6110 Å). The bond length in the D′ state (r₀ = 1.654 Å) has been obtained from a deperturbation of the 6110 Å band; it is only 0.035 Å longer than in the ground state, which indicates that electron promotion between the two π orbitals, nominally O(2pπ) and Fe(3dπ), has only a small effect on the strength of the bonding. The new isotope data still do not clarify the vibrational assignments of the higher levels, which are disorganized by extensive electronic perturbations.     

Isotopic fingerprint of the middle Olt River basin,Romania

One of the most important tributaries of the Danube River in Romania, the Olt River, was characterized in its middle catchment in terms of the isotopic composition using continuous flow–isotope ratio mass spectrometry (CF–IRMS). Throughout a period of 10 months, from November 2010 to August 2011, water samples from the Olt River and its more important tributaries were collected in order to investigate the seasonal and spatial isotope patterns of the basin waters. The results revealed a significant difference between the Olt River and its tributaries, by the fact that the Olt River waters show smaller seasonal variations in the stable isotopic composition and are more depleted in ¹⁸O and ²H. The waters present an overall enrichment in heavy isotopes during the warm seasons.     

Spontaneous current and DC bias induced current in nickel–metal hydride secondary battery

The responses to biasing a nickel–metal hydride secondary battery with a dc pulse train, as well as to spontaneous discharging, are studied. A comparison is made between the current during biasing, i _e, and the current during off-biasing, i _g. It is suggested that both currents arise from the motion of the same charge carriers in the electrolyte, possibly the OH⁻ ions. The only difference is that the motive force for i _e is a bias voltage, while the motive force for i _g is an open-circuit voltage of the battery. It is suggested that battery action proceeds by a single electrochemical reaction. In the course of discharging, the current drops abruptly by the formation of a resistive layer, possibly by depletion of the OH⁻ ions in the vicinity of the positive electrode.     

Estimation of lake water—groundwater interactions in meromictic mining lakes by modelling isotope signatures of lake water

Abstract

A method is presented to assess lake water–groundwater interactions by modelling isotope signatures of lake water using meteorological parameters and field data. The modelling of δ¹⁸O and δD variations offers information about the groundwater influx into a meromictic Lusatian mining lake. Therefore, a water balance model is combined with an isotope water balance model to estimate analogies between simulated and measured isotope signatures within the lake water body. The model is operated with different evaporation rates to predict δ¹⁸O and δD values in a lake that is only controlled by weather conditions with neither groundwater inflow nor outflow. Comparisons between modelled and measured isotope values show whether the lake is fed by the groundwater or not. Furthermore, our investigations show that an adaptation of the Craig and Gordon model [H. Craig, L.I. Gordon. Deuterium and oxygen-18 variations in the ocean and the marine atmosphere. In Stable Isotopes in Oceanographic Studies and Paleotemperature, Spoleto, E. Tongiorgi (Ed.), pp. 9–130, Consiglio Nazionale delle Ricerche, Laboratorio di Geologia Nucleare, Pisa (1965).] to specific conditions in temperate regions seems necessary.     

A new bound-exciton emission band in ZnSe crystals and multiplasmon optical transitions

We have investigated cathodoluminescence both in unannealed ZnSe crystals and in crystals annealed in a Bi melt at a temperature of 1200K for 120 h with subsequent quenching. In the wavelength range 450–480 nm we have detected a new line series I _i ^s -nLO-mPl consisting of the bound-exciton emission line I _i ^s with wavelength λ=455.9 nm and its plasmon and LO-phonon echoes I _i ^s -LO (λ ₁=461.3 nm), I _i ^s -2LO (λ ₂=466.8 nm), I _i ^s -3LO (λ ₃=472.4 nm), and I _i ^s -4LO (λ ₄=478.3 nm). We have determined the mean number of emitted LO phonons N _LO=2.2±0.1 per photon. It is shown that the observed finer structure of the band may be due to multiphonon optical transitions. At low plasma densities (ω _p ≪ω _LO ) the Coulomb interaction causes broadening of the I _i ^s -nLO series. In samples with denser plasma, in which the condition ω _p ⩽ω _LO is met, multiplasmon satellites of the series I _i ^s -nLO-mPl are observed. Theoretical calculations of the shape of the emission band agree with experiment. Fiz. Tverd. Tela (St. Petersburg) 41, 1176–1180 (July 1999)     

Investigation of growth responses in saprophytic fungi to charred biomass

We present the results of a study testing the response of two saprophytic white-rot fungi species, Pleurotus pulmonarius and Coriolus versicolor, to charred biomass (charcoal) as a growth substrate. We used a combination of optical microscopy, scanning electron microscopy, elemental abundance measurements, and isotope ratio mass spectrometry (¹³C and ¹⁵N) to investigate fungal colonisation of control and incubated samples of Scots Pine (Pinus sylvestris) wood, and charcoal from the same species produced at 300 °C and 400 °C. Both species of fungi colonise the surface and interior of wood and charcoals over time periods of less than 70 days; however, distinctly different growth forms are evident between the exterior and interior of the charcoal substrate, with hyphal penetration concentrated along lines of structural weakness. Although the fungi were able to degrade and metabolise the pine wood, charcoal does not form a readily available source of fungal nutrients at least for these species under the conditions used in this study.     

The Fate of [15N]Ammonium and [15N]Nitrate in the Soil of a 140-Year-Old Spruce Stand (Picea Abies) in the Fichtelgebirge (NE-Bavaria)

Abstract

A ¹⁵N tracer-experiment was carried out in a 140-year-old spruce stand (Picea abies (L.) Karst.) in the Fichtelgebirge (NE-Bavaria, Germany). Highly enriched (98 at%) [¹⁵N]ammonium and [¹⁵N]nitrate were applied as tracers by simulation of a deposition of 41.3 mol N ha^?1 with 11 water m^?2. To examine seasonal variations of uptake by spruce and understorey vegetation, different plots were labelled in spring, summer and autumn 1994.

One aim of the present study was to perfect a method of preparation of soil extracts for isotope ratio mass spectrometry (IRMS) measurements. Ammonium and nitrate from soil extracts were prepared for IRMS measurements by steam distillation and subsequent freeze drying. Additionally, tracer distribution and transformations in the soil nitrogen pools were examined. Ammonium, nitrate and total nitrogen were examined in the organic layer and the upper 10 cm of the mineral soil during 3 months after the first tracer application in spring 1994.

In July 1994, three months after tracer application, 40% of the [¹⁵N]ammonium label and 29% of the [¹⁵N]nitrate label, respectively, were recovered in the total N pool of the investigated soil horizons. In the organic layer the L/Of horizon retained most of the recovered tracers. Nitrification, immobilisation and mineralisation occurred even under the conditions of high soil acidity at the study site.     

多层异质结构中的声学声子输运

在连续弹性近似下，采用转移矩阵方法，研究了由不同含Al浓度的异质结(GaAs/Al_{xiGa1-xiAs)所构成的对称多层异质结构中的声学声子输运性质.结果表明：该结构中的声子透射谱具有与同组分厚度超晶格(GaAs/AlAs )不一样的特征，具体体现在透射曲线振荡幅度与频率等方面；声子透射谱特征与对称异质结构中AlxiGa1-xiAs层的含Al浓度xi(i表示对称轴两边的第i层)的分布有很大的关系，具体表现为：当xi随i的增加而递减时，透射谱线除主波谷外较平滑；而当xi随i的增加而递增时，透射谱振荡明显增大，且主波谷被分裂.声子透射系数还依赖于异质结组分层的厚度，尤其是AlxiGa1-xiAs的厚度.另外，异质结的层数对声子输运也产生一定的影响. 关键词： 输运 声子 异质结}     

Study of PEO—PPO—PEO Copolymers Conformational Changes: Viscosity and Dynamic Light Scattering Measurements

The self-assembly behaviour of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly (ethylene oxide) copolymers, (EO)₁₃(PO)₃₀(EO)₁₃ (Pluronic L64), and (EO)₇₀ (PO)₃₀(EO)₇₀ (Pluronic F68) in water and in p-xylene has been elucidated by using viscosity and dynamic light scattering measurements to investigate the effects of hydrophilic chains length on their conformational changes. The viscosity measurements were performed for a range of temperature varying from 27°C to 60°C and concentration from 4 to 60 mg/ml. The variation of the viscosity and the conformational changes in aqueous solution depends on the kinds of interactions and the balance between excluded volume effects and hydrophobic interactions. Some dynamic light scattering measurements were also performed at room temperature for the same range of concentration to provide more information on the micellar structures in aqueous and organic solution.     

Isotope effects in the enzymatic oxidation of tryptamine to 3-indolyl-acetaldehyde

The reaction mechanisms of the enzymatic deamination of tryptamine catalysed by the enzyme monoamine oxidase (MAO, EC 1.4.3.4) were investigated using the kinetic isotope effect and solvent isotope effect methods. The numerical values of these deuterium effects in the (1S) and (1R) positions of tryptamine were determined using the non-competitive spectrophotometry. The deuterium-labelled isotopologue [(1S)-²H]tryptamine was obtained in two steps by enzymatic coupling of indole with S-methyl-l-cysteine in a deuterated medium followed by enzymatic decarboxylation of the resulting [2-²H]-l-tryptophan. [(1R)-²H]tryptamine was obtained by enzymatic decarboxylation of l-tryptophan in the fully deuterated medium.