Analysis of n(87Sr)/n(86Sr), δ88Sr/86SrSRM987 and elemental pattern to characterise groundwater and recharge of saline ponds in a clastic aquifer in East Austria

Elemental and isotopic pattern of n(⁸⁷Sr)/n(⁸⁶Sr) and δ⁸⁸Sr/⁸⁶Sr_SRM987 were used to characterise groundwater and recharge of saline ponds in a clastic aquifer in East Austria. Therefore, shallow, artesian and thermal groundwaters of the investigated aquifer along with rainfall and rivers were analysed using (MC) ICP-MS. The n(⁸⁷Sr)/n(⁸⁶Sr) ratio and elemental pattern changed with aquifer depth as a result of progressing bedrock leaching and dissolution with increasing groundwater residence time. The n(⁸⁷Sr)/n(⁸⁶Sr) ratio of shallow groundwater below saline ponds of 0.71019?±?0.00044 was significantly different from thermal groundwater of 0.71205?±?0.00035 (U, k?=?2). In contrast to previous theories, this result suggested no recharge of saline ponds by upwelling paleo-seawater. Isotope pattern deconvolution revealed that rainfall accounted to about 60% of the n(⁸⁷Sr)/n(⁸⁶Sr) ratio of shallow groundwater below saline ponds. The δ⁸⁸Sr/⁸⁶Sr_SRM987 values of groundwater decreased from about 0.25 ‰ in most shallow, to predominantly negative values of about –0.24 ‰ in artesian groundwater. This result indicated leaching and dissolution of weathered minerals. In turn, the δ⁸⁸Sr/⁸⁶Sr_SRM987 of deep thermal groundwater showed positive values of about 0.12 ‰, which suggested removal of ⁸⁶Sr from solution by carbonate precipitation. These results highlight the potential of δ⁸⁸Sr/⁸⁶Sr_SRM987 signature as an additional geochemical tracer.     

Stable Isotope Geochemistry of Antarctic Salt Efflorescences

Salt efflorescences consisting of gypsum sampled mainly in the Schirmacher Oasis have been analyzed for the isotopic composition of the water of crystallization and of the sulphate-sulphur. For comparison, a few samples from other Antarctic locations (Guettard Range, Prince Charles Mts., Insel Mts.) were included in the study. The isotopic variations of the water of crystallization of secondary gypsum and the calculated isotopic composition of the mother solution reflect the local climatic conditions during the precipitation of the efflorescences. It is therefore possible to obtain qualitative information about the climatic conditions prevailing in the studied region.     

60 MeV/u 18O离子同天然铀反应钡同位素截面的测定

通过60MeV/u18O离子照射天然铀靶产生Ba放射性同位素,使用BaCl2沉淀法从大量铀和其它反应产物混合物中分离出Ba.通过离线γ谱学方法测量了Ba样品的γ射线单谱,根据Ba同位素特征γ射线峰的强度及其它相关数据计算了Ba同位素的生成截面.发现在厚铀靶的情况下,缺中子Ba同位素仍有较高的截面. The radioactive Ba isotopes were produced by 60 MeV/u~(18)O ion bombardment of natural uranium. Ba was separated from U and the reaction product mixture by BaCl_(2) precipitation. The Ba fraction was measured by off-line γ-ray spectroscopy. The cross sections of the individual Ba isotope were calculation based on the intensities of the character γ-ray peaks of Ba isotopes and other relative information. It was found that the n-deficient Ba isotopes have higher cross sections using the thick uranium targets.     

Preparation of Zinc Hydroxystannate Coated Dendritic-Fibrillar Barium Carbonate and its Flame Retardant Effect on Soft Poly (Vinyl Chloride)

Abstract

Zinc hydroxystannate (ZHS) coated dendritic-fibrillar barium carbonate (ZHS/BaCO_3-F) was obtained by a simple ultrasonic assisted method at room temperature without any guide reagent; the flame retardant soft poly (vinyl chloride) (S-PVC) treated with ZHS/BaCO_3-F was prepared by melt blending and studied by the limiting oxygen index (LOI), univeral tensile testing machine, thermogravimetric analyzer-Fourier transform infrared spectroscopy (TGA/FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that ZHS/BaCO_3-F had a good dispersion in the PVC matrix, increased the LOI value and reinforced the S-PVC. The ZHS/BaCO_3-F played its role during the first degradation stage of S-PVC; the integrated effects of the earlier dehydrochlorination of ZHS on PVC, the reaction of ZHS/BaCO_3-F and HCl, and the thermal degradation of ZHS resulted in the production of H₂O, CO₂, olefins, aryl compounds, carboxylic compounds and alcohols, and the decrease of HCl production.     

离子注入/辐照引起Al2O3单晶的改性研究

600K温度下用110keV的He^＋,Ne^＋,Ar^＋离子注入及320K温度下用230MeV的^208Pb^27＋辐照Al2O3单晶样品,研究了离子注入和辐照对Al2O3单晶样品结构和光学特性的影响。从测得的光致发光谱可以清楚地看到,所有样品在波长为375,413和450nm处出现了强的发光峰。且所有5×10^16ion／cm^2注入样品的发光峰均最强。经过高能Pb辐照后的样品,在390nm处出现了新的发光峰。透射电镜分析发现在注入氖样品100nm入射深度以内形成了高浓度的小空洞（1-2nm）,在Ne沉积区域有少量大空洞形成。傅立叶变换红外光谱分析发现,波数在460-510cm^-1间的振动吸收带经过离子辐照后展宽,随着辐照量的增大,该振动吸收强度显著减弱。1000—1300cm^-1对应Al-O-Al桥氧伸缩振动模式的吸收带,辐照后向高波数方向移动。对离子注入和辐照对Al2O3单晶样品结构损伤机理进行了初步探讨。Single crystal sapphire （Al2O3 ） samples were implanted at 600 K by He, Ne and Ar ions with energy of 110 keV to doses ranging from 5 × 10^16 to 2× 10^17 ion/cm^2 or irradiated at 320 K by ^208Pb^27＋ ion with energy of 1.1 MeV/u to the fluences ranging from 1 × 10^12 to 5 × 10^14 ion/cm^2. The modification of structure and optical properties induced by ion implantation or irradiation were analyzed by using photoluminescence（PL） and Fourier transformation infrared spectrum（FIR） spectra and transmission electron microscopy（ TEM ） measurements. The PL measurements showed that absorption peaks located at 375,413 and 450 nm appeared in all the implanted or irradiated samples, the PL intensities reached up to the maximum for the 5 × 10^16 ion/cm^2 implanted samples. After Pb-ion irradiation, a new peak located at 390 nm formed. TEM analyses showed that small size voids,（ 1--2 nm） with high density were formed in the region from the surface till to about 100 nm in depth and also large size Nebubble formed in the Ne-doped region. From the obtained FTIR spectra, it was found that Pb-ion irradiation induced broadening of the absorption band in 460-510 cm^-1 and position shift of the absorption band in 1 000- 1 300 cm^- 1 towards to high wavenumber. The possible damage mechanism in single crystal sapphire induced by energetic ion implantation or irradiation was briefly discussed.     

High-purity Zirconium under Niobium ion implantation: possibility of a dynamic precipitation?

High-purity (6N purity) Zirconium was subjected to different Niobium ion (Nb⁺) fluences in a particle accelerator. Grazing incidence X-ray diffraction confirmed subsurface phase transformation. While an approximate scaling was noted between Nb⁺ fluence and quantum of phase transformation, the sample subjected to the highest ion irradiation also showed significant subsurface shear residual stresses (τ₁₃). Molecular dynamics simulations, considering momentum transfer, revealed a drop in τ₁₃ beyond a critical displacements per atom or Nb⁺ fluence. High-resolution cross-sectional transmission electron microscopy (HRXTEM) confirmed formation of bcc (body-centred cubic) β phase and also linked τ₁₃ with such transformation. HRXTEM revealed, at about 100 nm depth, presence of 10–15% β with 2–15 nm size. The β particles and the surrounding α also had significant microscopic shear strains. The dynamic nature of the Nb implantation is expected to create fluctuations in temperature, Nb concentration and relative lattice damage. Such fluctuation, on the other hand, is/was hypothesized to dynamically alter the critical nuclei size: a clear possibility of ‘dynamic precipitation’.     

Thermal Ionization and Inductively Coupled Plasma Mass Spectrometry: Potential for Application to Studies on the Biokinetics of Molybdenum in Humans

Abstract

The use of stable isotopes as tracers in biokinetic investigations provides a means to obtain important metabolic data directly in humans without exposing the subjects to undue risks. In this work, three types of mass spectrometers are compared with regard to the determination of the abundances of stable isotopes of molybdenum in natural and enriched aqueous samples. The data show a good response of thermal ionization mass spectrometry (TIMS) and of high-resolution inductively coupled plasma mass spectrometry (ICPMS) to the isotopic enrichment of the samples, whereas conventional quadrupole ICPMS shows an unsatisfactory reproducibility of the results. Moreover, only TIMS can achieve an accuracy of better than 1% for the obtained isotopic ratios. Although a tedious procedure for the preparation of the biological samples is required and less sensitivity is achieved as compared to ICPMS, TIMS still seems to be method of choice for the accurate assessment of isotope ratios as required in multitracer studies on human biokinetics of trace metals.