Production of phthalate esters by nuisance freshwater algae and cyanobacteria

Phthalate esters are widely distributed pollutants which originate from synthetic plasticizer and are known to act as toxicants as well as environmental pheromones in the aquatic ecosystems. From investigating sixteen species of freshwater algae and cyanobacteria we revealed that some of them were capable of producing either di(n-butyl)phthalate (DBP) or mono(2-ethylhexyl)phthalate (MEHP) or both. These phthalate esters would be released into the environment under stress conditions. The incubation of the cells in culture medium containing NaH¹³CO₃ confirmed that both phthalates were de novo synthesized by the studied cells. This study suggested that the nuisance freshwater micro-algae and cyanobacteria growing in eutrophic waters might affect the aquatic ecosystem via the production of these phthalate esters.     

Investigation of the geographical provenance of the beer available in South Korea using multielements and isotopes

Although beer has the largest share of the global alcoholic beverage market, only limited studies of beer have been performed in terms of elemental and isotopic compositions. Here, we measured elemental and isotopic compositions—including carbon and oxygen isotopes as well as ⁸⁷Sr/⁸⁶Sr ratios—of beers available in South Korea to examine geographical differences. Although most of the elements analyzed in this study were not markedly different between the beer samples, there was a clear distinction in the isotopic compositions of the samples. δ¹³C_DIC values indicated that most of the beer samples were produced from C₃ plants, such as barley or wheat. δ¹⁸O values allowed the samples to be discriminated by latitude, reflecting a negative correlation between latitude and isotopic composition. Similarly, ⁸⁷Sr/⁸⁶Sr ratios were different between the samples due to the bedrock. Statistical analysis of the combination of elemental and isotopic compositions showed a clear difference between the beer samples according to the geographical provenance on a continental scale. This study demonstrated a powerful method for distinguishing diverse beers according to their geographical provenance, and will make an important contribution to research into discrimination of the geographical origin of diverse processed foods available commercially.     

甘肃天水宽沟金矿床同位素地球化学特征研究

通过对李子园地区宽沟金矿床氢、氧、硫、铅同位素特征的分析研究,讨论了该矿区成矿流体性质、来源及成矿物质来源等问题。氢氧同位素结果表明,宽沟金矿床成矿流体是一种混合源,以岩浆热液为主,有部分大气降水和变质热液的混入。硫同位素组成表明, 宽沟金矿床矿石硫以岩浆硫为主,同时混入了地层中的硫。铅同位素组成表明,成矿物质主要来源于深部的下地壳和上地幔,为壳幔混源,在成矿流体向上运移的过程中,有地层铅的混入,成矿与燕山期石英正长岩体关系密切。     

Intrinsic isotopic C labelling of polyphenols

The intrinsic isotopic labelling of plants with ¹³CO₂ is an effective method to generate highly labelled compounds using photosynthesis and avoiding labour-intensive complex organic syntheses. In this study, the intrinsic isotopic labelling of polyphenols in parsley, spinach and peppermint is shown for the first time. The plants were grown in an atmosphere where ¹²CO₂ was replaced by ¹³CO₂, in order to generate highly labelled compounds. The total content of ¹³C as well as the individual polyphenols were analysed by Isotopic Ratio-MS and HPLC–Iontrap-MSⁿ.     

Dynamic and kinetic modeling of isotopic transient responses for CO insertion on Rh and Mn–Rh catalysts

Isotopic transient tracer techniques have been employed to study heterogeneous hydroformylation on Rh/SiO₂ and Mn–Rh/SiO₂. Pulse injection of D₂ and allowed tracing of the deuterium and CO incorporation pathway into the aldehyde product. The d₁- and d₂-propionaldehyde responses showed a double-peak, or two-hump, response to the D₂ pulse, while showed a single-hump response to the pulse. Analysis of the product responses to the D₂ pulse in CO/H₂/C₂H₄ and CO/H₂/C₂H₄/C₂H₅CHO suggests that the first hump of the d₁- and d₂-propionaldehyde responses was due to rapid H/D exchange with adsorbed propionaldehyde via enol intermediates. The decay of the second hump was due to reaction of adsorbed acyl with spillover hydrogen/deuterium. The response was due to CO insertion followed by acyl hydrogenation. Compartment modeling of the product responses from the and D₂ pulse inputs allowed determination of residence times of adsorbed intermediates, surface coverages of adsorbed intermediates, and the elementary rate constants for acyl hydrogenation and CO insertion. Elementary rate constants for acyl hydrogenation determined from this study were consistent with the value calculated by transition state theory (TST). The addition of Mn promoter to Rh/SiO₂ increased coverages of , , and and shifted the rate-limiting step for propionaldehyde formation. Acyl hydrogenation is the rate-limiting step on Rh/SiO₂ while CO insertion and acyl hydrogenation are both kinetically significant on Mn–Rh/SiO₂.     

SEPARATION OF STABLE NITROGEN ISOTOPES BY ION EXCHANGE CHROMATOGRAPHY

ABSTRACT

The ion exchange chromatography technique was used for the enrichment of nitrogen 15 (¹⁵N). A set of columns filled with the ion exchange resin Wofatit KPS (medium porosity type) with 5.4?cm I.D. and 1.5?m height was set up. Ammonia NH₄ ⁺/NH₃ aq. was chosen as the isotopic exchange system. The ammonium bands formed in the columns were eluted by a solution of sodium hydroxide. The isotope separation factor, ?, was found to decrease with increasing temperature or ammonia concentration. Operational conditions of temperature and ammonium concentration were proposed as the optimum for the production of the enriched isotope by using the present process. Results showed that: (1) the rear part of the band is enriched in ¹⁵N, while the frontal part is depleted; (2) it is possible to obtain 7.6?at. % of ¹⁵N after a 60?m displacement of the ammonium band. The analytical determination of the samples was made by emission spectrometry (NOI-6E).     

Computational Fluid Dynamics Simulation of 13CO Distillation in Structured Packing

Physical 3D models were established for corrugated packing used in the enrichment of the isotope ¹³C. Computational fluid dynamics (CFD) simulation results indicated that common corrugated packing was not well wetted when used for isotope distillation. It is concluded that liquid misdistribution in the packed tower results from the structure of the packing rather than from the height of the packing beds. The existence of entrainment was also demonstrated by CFD simulation. It is proved that mass transfer equations based on the Nusselt theory are not suitable for distillation calculation in such a corrugated packing system. By comparison, the recently developed structured packing model with a corrugation geometry based on the right‐angled triangle, known as Zigzag‐pak, describes vapor‐liquid distribution properties well and has significant advantages over common corrugated packing due to its better liquid distribution character.     

同位素分析法在三山岛金矿的应用

三山岛矿区地下水质有海水、第四系水、基裂岩隙水、地下热水、淡水等。为了适应矿区生产的需要,需对水质进行分析。但是,常规的水质简分析法只能鉴别水的类型,不能提供其它资料,为此采用同位素分析法。该法不仅能验证水文地质研究提供的结果,还能提供水文地质研究不易取得的数据与资料,如地下水相对停留时间,不同成因不同成分的地下水补给源的补给量及其比例。     

Commissioning of a high-resolution collinear laser spectroscopy apparatus with a laser ablation ion source

Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility （BRIF） and the future High Intensity Heavy-ion Accelerator Facility （HIAF）,we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system.The overall performance of this state-of-the-art technique was eva...     

Detection of counterfeit scotch whisky by H and O stable isotope analysis

Neat Scottish whiskies and the local source water used for and during whisky production have been analysed for their ²H and ¹⁸O isotopic composition by High Temperature Conversion–Isotope Ratio Mass Spectrometry (TC/EA–IRMS). With coefficients of determination R² for δ²H and δ¹⁸O of 0.71 and 0.88, respectively, measured δ²H and δ¹⁸O values for water used in the production of Scottish whisky were found to be well correlated with the δ²H and δ¹⁸O values observed for the corresponding whiskies. By plotting bulk ²H against bulk ¹⁸O isotope abundance data of authentic whisky and counterfeit whisky samples it was possible to discriminate between samples of authentic whisky and samples of counterfeit whisky.