High Strontium Research Articles

High and differential strontium tolerance in germinating dimorphic seeds of Salicornia europaea

Salicornia europaea, a highly salt-tolerant halophyte, is potentially resistant to other metals because plant stress tolerance partly relies on common physiochemical mechanisms. Large median seeds and small lateral seeds of S. europaea have high salt tolerance and display contrasting germination responses. Thus, we hypothesised that dimorphic seeds of S. europaea might also have high and differential strontium (Sr) tolerance during germination. Both types of seeds were incubated in different SrCl2 concentrations at 25°C. 0-300 mmol L-1 SrCl2 did not significantly affect germination of median seeds. However, for lateral seeds, relatively high concentrations (≥ 200 mmol L-1) dramatically inhibited germination. The simulated critical value (when germination percentage is 50%) was 502 mmol L-1 for median seeds and 224 mmol L-1 for lateral seeds. Dimorphic seeds of S. europaea are highly tolerant to Sr stress and large median seeds display higher tolerance. The results suggest that direct seeding of large seeds of S. europaea might be an effective method to remediate heavy Sr-polluted soils.

Assessing Strontium and Vulnerability to Strontium in Private Drinking Water Systems in Virginia

A total of 1.7 million Virginians rely on private drinking water (PDW) systems and 1.3 million of those people do not know their water quality. Because most Virginians who use PDW do not know the quality of that water and since strontium poses a public health risk, this study investigates sources of strontium in PDW in Virginia and identifies the areas and populations most vulnerable. Physical factors such as rock type, rock age, and fertilizer use have been linked to elevated strontium concentrations in drinking water. Social factors such as poverty, poor diet, and adolescence also increase social vulnerability to health impacts of strontium. Using water quality data from the Virginia Household Water Quality Program (VAHWQP) and statistical and spatial analyses, physical vulnerability was found to be highest in the Ridge and Valley province of Virginia where agricultural land use and geologic formations with high strontium concentrations (e.g., limestone, dolomite, sandstone, shale) are the dominant aquifer rocks. In terms of social vulnerability, households with high levels of strontium are more likely than the average VAHWQP participant to live in a food desert. This study provides information to help 1.7 million residents of Virginia, as well as populations in neighboring states, understand their risk of exposure to strontium in PDW.

Distinction of strontium isotope ratios between water-soluble and bulk coal fly ash from the United States

Coal ash is one of the largest industrial waste streams in the United States and contains elevated concentrations of hazardous elements that could pose environmental and human health risks. Due to the relatively high strontium concentrations in coal ash and the distinctive 87Sr/86Sr ratios, strontium isotopes have been utilized to trace coal ash contaminants in impacted water resources. While previous studies have characterized the Sr isotope ratios for the water-soluble Sr derived from coal ash, the strontium isotopic composition of the bulk coal ash has not been systematically evaluated. In the current study, we report the 87Sr/86Sr ratios of bulk and water-soluble Sr in fly ash derived from coals of the three major coal-producing basins in the U.S., the Appalachian Basin, Illinois Basin, and Powder River Basin. The data show a wide range of 87Sr/86Sr ratios in the bulk fly ash samples (0.710788–0.722311), with the most radiogenic 87Sr/86Sr ratios in fly ash originating from Illinois Basin coals (0.718029 ± 0.003365; n = 16), followed by those from Appalachian Basin coals (0.712641 ± 0.000860; n = 16), and those from Powder River Basin coals (0.711663 ± 0.000489; n = 7). The 87Sr/86Sr ratios in the water leachates are significantly lower than the 87Sr/86Sr ratios of the bulk fly ash for Illinois Basin and Appalachian Basin (0.711660 ± 0.001172 and 0.710694 ± 0.000317, respectively, p-value < 0.01), whereas there is no significant difference for the Powder River Basin fly ash (0.711666 ± 0.000456, p-value = 0.13). These isotopic differences most likely reflect the different mineralogical compositions of the studied fly ash and the differential solubility of carbonate phases with low 87Sr/86Sr ratios relative to more radiogenic silicate phases. Overall, the distinction between the strontium isotope ratios of bulk fly ash versus water-soluble fly ash is important, as it refines the application of strontium isotopes as a forensic tracer for tracking coal ash spills and contamination in the environment.

SALT revisits DY Cen: a rapidly evolving strontium-rich single helium star

ABSTRACT The hydrogen-deficient star DY Cen has been reported as an R CrB-type variable, an extreme helium star (with some hydrogen), and as a single-lined spectroscopic binary. It has been associated with a dramatic change in visual brightness and colour corresponding to a change in effective temperature ( Teff) of some 20 000 K in the last century. To characterize the binary orbit and Teff changes more precisely, new high-resolution spectroscopy has been obtained with SALT. The previous orbital period is not confirmed; previous measurements may have been confused by the presence of pulsations. Including data from earlier epochs (1987, 2002, and 2010), self-consistent spectral analyses from all four epochs demonstrate an increase in Teff from 18 800 to 24 400 K between 1987 and 2015. Line profiles demonstrate that the surface rotation has increased by a factor of 2 over the same interval. This is commensurate with the change in Teff and an overall contraction. Rotation will exceed critical if contraction continues. The 1987 spectrum shows evidence of a very high abundance of the s-process element strontium. The very rapid evolution, non-negligible surface hydrogen and high surface strontium point to a history involving a very late thermal pulse. Observations over the next 30 yr should look for a decreasing pulsation period, reactivation of R CrB-type activity as the star seeks to shed angular momentum and increasing illumination by emission lines from nebular material ejected in the past.

Facile synthesis of ultrafine and high purity spherical strontium carbonate via gas-liquid reaction

In this work, a simple gas-liquid precipitation reaction was developed to fabricate spherical strontium carbonate (SrCO3) particles using strontium hydroxide (Sr(OH)2), carbon dioxide (CO2) and ethylene diaminetetraacetic acid strontium salt (EDTA-Sr) as raw materials. The effects of the concentration of EDTA-Sr and Sr(OH)2, airflow rate of CO2 and reaction temperature on the morphology of SrCO3 were investigated. The results showed that spherical SrCO3 particles can be formed when the concentration of EDTA-Sr reached 0.02 M as well as that of Sr(OH)2 was less than 0.1 M. The airflow rate of CO2 gas had little effect on the spherical morphology, and SrCO3 microsphere with good dispersion could be obtained when the reaction temperature reached 50 °C. Under the optimal conditions ([EDTA-Sr] = 0.02 M, [Sr(OH)2] = 0.1 M, 50 °C, [CO2] = 1 l min−1), high purity spherical SrCO3 particles with diameter of 200–800 nm can be easily obtained. Finally, the growth mechanism of spherical SrCO3 has been preliminarily presented, which indicated that EDTA-Sr is an excellent structure-directing agent for forming pherical SrCO3 particles. Our work offers an effective method for large-scale production of high purity spherical SrCO3.

Influence of the strontium content on the performance of La1-xSrxMnO3/Bi1.5Er0.5O3 composite electrodes for low temperature Solid Oxide Fuel Cells

The possibility to use bilayer electrolytes based on bismuth oxide conductors should lead to a drastic decrease of solid oxide fuel cell (SOFC) operation temperature and calls for a reevaluation of some of the parameters optimized for high temperature applications. In this work we reinvestigate the promising La1-xSrxMnO3/Bi1.5Er0.5O3 (LSM/ESB) composite electrodes, varying the strontium content from x ~ 0.2, the typical high temperature LSM composition, to evaluate the optimum composition. Increasing the strontium content up to x = 0.4–0.5 leads to a 14% decrease of the activation energy, resulting in a 50% decrease in the polarization resistance of symmetric cells at 500 °C compared to the traditional La0.85Sr0.15MnO3 composition with similar microstructure. The electrode performance is deteriorated by further increase in the strontium content. Based on surface composition, investigated by low energy ion scattering, we show that the SrO surface segregation proposed as the main deterioration mechanism for LSM based HT-SOFC is not an issue below 800 °C. Furthermore, we propose that the increase in performance is related to the decrease of cationic vacancies in LSM observed for high strontium content, which may help the oxygen dissociation and surface transport.

Waste recycling of cathode ray tube glass through industrial production of transparent ceramic frits

ABSTRACTCathode ray tube (CRT) glass contains significant amounts of alkali and alkaline earth oxides, making it a useful by-product for use in the ceramics industry. Among the various alkali oxides present, those of strontium (SrO), calcium (CaO), and magnesium (MgO) are well known flux materials used widely in the ceramics industry. The most effective flux, SrO, is also a limited resource. In this study, we aimed to develop an environmentally friendly, low-cost method for recycling CRT waste by using it to produce transparent ceramic frits on an industrial scale. Four different samples were fabricated containing between 13 and 25 wt.% CRT panel glass. The color values, sintering behaviors, phases, and microstructural properties of the corresponding samples were analyzed and compared. The results indicate that a composition containing 25 wt.% CRT panel glass could pass the ISO 10545 test. Thus, the results confirm that CRT glass can be used to inexpensively produce transparent ceramic frits at an industrial scale.Implications: The recycling of electronic waste (e-waste), including CRT waste, has increased by high rates of computer and TV consumption. This increase in consumption is likely to increase the rate at which CRTs are discarded. However, CRTs cannot be recycled in the desired amount. Owing to the high silicate, barium and strontium content of CRTs, it has great potential for glass ceramics such as frits. CRT panel glass to produce commercial transparent frit at low cost through an industrial production route for use in single-fire sintered products. Thus, CRT wastes can be recycled cost-effective, sustainable and environmentally friendly.

The origin of solutes in groundwater in a hyper-arid environment: A chemical and multi-isotope approach in the Atacama Desert, Chile

The major ion and the multi-isotopic composition (87Sr/86Sr, δ11B, δ34S(SO4) and δ18O(SO4)) of groundwater from the Central Depression in northern Chile is investigated to identify the origin of groundwater solutes in the hyper-arid core of the Atacama Desert. The study area is between the Cordillera de Domeyko and the Central Depression, at latitudes 24–25°S, and is characterized by near-zero air moisture conditions, rare precipitation and very limited runoff. Groundwater composition varies from Ca-HCO3 to Ca, Na-SO4 type below elevations of 3400 m a.s.l. The rCl/rBr ratio of meteoric waters and groundwater overlap, but significantly increase in the aquifer as salinity goes up due to evapoconcentration far from the Domeyko Cordillera. The wind-displaced dust originating in the Central Depression (87Sr/86Sr: 0.706558–0.710645; δ34S(SO4): 0 to +4‰) affects the precipitation composition in the highest parts of the Domeyko Cordillera (87Sr/86Sr: 0.706746–0.709511; δ34S(SO4): +1 to +6‰), whose δ34S(SO4) and δ11B values are greatly different from marine aerosols, discarding its contribution to dust at this distance inland. Sr and S isotopic values in groundwater indicate a strong relation with three main geological units: i) Paleozoic rocks contribute high radiogenic strontium isotope ratios to groundwater (0.707011–0.714862), while sulphate isotopic composition is probably acquired from atmospheric dust (>− 1.4‰), ii) Jurassic marine limestones contribute low-radiogenic strontium isotopic ratios to groundwater (<0.70784), while sulphate can be related to oxidized sulphides that change the isotopic signatures of sulphur (<−1.2‰), and iii) mixed salts in the Atacama Gravels contribute lower radiogenic strontium isotopic ratios and sulphate to groundwater (87Sr/86Sr: <0.707324; δ34S(SO4): +0.1 to +7.7).These three processes reflect water-rock interactions. The δ11B of groundwater generally up to +13‰, does not increase along the regional groundwater flow path, discarding fractionation by interaction with clays. These results improve the understanding of the groundwater evolution in hyper-arid systems through a new conceptual model.

Local structure of relaxor ferroelectric SrxBa1−xNb2O6 from a pair distribution function analysis

Pair distribution function analysis of neutron-scattering data and of ab initio molecular dynamics results have been employed to study short-range structural correlations and their temperature dependence in a heavily disordered dielectric material ${\mathrm{Sr}}_{x}{\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{Nb}}_{2}{\mathrm{O}}_{6}\phantom{\rule{4pt}{0ex}}(x=0.35,\phantom{\rule{0.28em}{0ex}}0.5$, and 0.61). Intrinsic disorder caused by a partial occupation of the cationic sites by differently sized Sr and Ba atoms and their vacancies introduces important local strains to the structure and directly influences the Nb-${\mathrm{O}}_{6}$ octahedra tilting. The resulting complex system of tilts is found to be both temperature and Sr-doping sensitive with the biggest tilt magnitudes reached at low temperatures and high strontium contents, where ferroelectric relaxor behavior appears. We find evidence for two Nb-${\mathrm{O}}_{6}$ subsystems with different variations of niobium-oxygen bond lengths, distinct dynamics, and disparate levels of deviation from macroscopic polarization direction. These findings establish a detailed picture of the local structure of ${\mathrm{Sr}}_{x}{\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{Nb}}_{2}{\mathrm{O}}_{6}$ and provide a deeper insight into the origins of the materials dielectric properties.

In vitro Response of Human Osteoblasts Cultured on Strontium Substituted Hydroxyapatites

The goal of this study was to analyze the response of osteoblasts cultured on strontium substituted hydroxyapatites (HAP-Sr) of well-defined high crystallinity deposited as thin films on glass plates. Up to now, this aspect has not been carefully investigated in the context of bio-ceramics. In this study, we present the osteoblasts activity on synthesized HAP-Sr for different amounts of strontium substitution for calcium within the hydroxyapatite (Ca10(PO4)6(OH)2, HAP) lattice, namely HAP-5%Sr, HAP-10%Sr, HAP-15%Sr and HAP-59.2%Sr (Sr-HAP, of formula Sr10(PO4)6(OH)2), in comparison with stoichiometric pure HAP, chosen as control. Each bio-ceramic was deposited as thin multilayers self-assembled substrate (scaffold) and chemically bonded to the surface of glass plates. These coatings revealed by AFM and SEM imaging a granular texture formed from bio-ceramic nanoparticles. They possessed a high degree of crystallinity, i.e. 68% to 86%, depending on the Sr amount within the HAP lattice, as judged by XRD. Osteoblasts were cultured up to 21days and displayed enhanced adhesion and proliferation particularly evidenced on relatively high strontium contents (especially 5 and 10 weight %, determined by SEM-EDX), where the alkaline phosphatase activity and type I collagen were strongly evidenced. These bio-ceramics showed a high in vitro biocompatibility stimulating the activity of osteoblasts in the process of bone formation. These nano biomaterials can have applications in orthopedic and dental surgery improving the osteointegration as coatings of bone implants as well as for bone repair and regeneration.

Strontium marking on otoliths of Paralichthys olivaceus based on immersion experiments

PDF HTML阅读 XML下载 导出引用 引用提醒 基于浸泡法的牙鲆耳石锶标记技术研究 DOI: 作者: 作者单位: 1. 中国水产科学研究院北戴河中心实验站, 河北 秦皇岛 066100;2. 河北科技师范学院, 河北 秦皇岛 066600;3. 中国水产科学研究院淡水渔业研究中心, 江苏 无锡 214081;4. 中国水产科学研究院黄海水产研究所, 山东 青岛 266071;5. 青岛海洋科学与技术国家实验室海洋生态与环境科学功能实验室, 山东 青岛 266200 作者简介: 司飞(1981-),男,硕士,工程师,主要从事渔业资源增殖与养护研究.E-mail:beyond702@163.com 通讯作者: 中图分类号: S937 基金项目: 现代农业产业技术体系国家海水鱼产业技术体系（CARS-47-Z03）；公益性行业（农业）科研专项经费项目（201303050）. Strontium marking on otoliths of Paralichthys olivaceus based on immersion experiments Author: Affiliation: 1. Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China;2. Hebei Normal University of Science and Technology, Qinhuangdao 066600, China;3. Freshwater Fisheries Research Center of Chinese Academy of Fishery Sciences, Wuxi 214081, China;4. Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China;5. Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266200, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了探究耳石微化学标记技术在牙鲆增殖放流中的应用，以全长（1.56±0.16） cm的牙鲆幼鱼为研究对象，在其养殖水中分别添加0.5 mg/L、2 mg/L、8 mg/L、32 mg/L SrCl2·6H2O，以无添加SrCl2·6H2O组为对照组，人为改变牙鲆幼鱼生存环境中Sr2+浓度72 h，研究不同浓度SrCl2·6H2O对牙鲆耳石锶标记效果。标记期间每24 h换水1次，换水量为50%，换水后补加SrCl2·6H2O至原始浓度，记录各浓度组标记期间及标记后的鱼苗死亡数量。利用X射线电子探针微区分析仪（EPMA）对耳石样本进行分析，定量线分析结果表明，0.5 mg/L、2 mg/L SrCl2·6H2O浸染不能形成牙鲆耳石锶标记。8 mg/L浓度组出现Sr峰区，Sr/Ca（Sr：Ca×1000） 均值为4.50~6.60，Sr峰值为5.49~8.49。32 mg/L浓度组Sr峰区均值为4.83~7.55，Sr峰值为5.62~11.04。这说明8 mg/L、32 mg/L SrCl2·6H2O可对牙鲆耳石进行锶标记。但8 mg/L浓度组出现未标记样本，且Sr峰区均值较32 mg/L浓度组低。32 mg/L浓度组Sr/Ca比值显著增高，即锶标记的Sr/Ca比值为6.61±0.86，与标记前和对照组Sr/Ca比值差异均显著（·6H2O浓度组开始，耳石出现红色“高锶标记环”，与耳石本底颜色对比明显，且随浓度升高，红色“高锶标记环”由浅变深，锶标记效果明显增强。单因素方差分析和Duncan多重比较结果显示，各浓度组全长、体重与对照组差异不显著（检验，各浓度组在浸泡标记期间死亡率及标记后养殖90 d的累积死亡率无显著性差异（O对牙鲆幼鱼死亡率无显著影响。因此，32 mg/L SrCl2·6H2O为最佳标记浓度。 Abstract:To explore the method of microchemistry marking on the otolith of Japanese flounder, , during the process of proliferation and release, the juveniles with a total length of (1.56±0.16) cm were immersed at four different concentrations (0.5, 2, 8, and 32 mg/L) of SrCl2·6H2O for 72 h to detect the Sr sedimentation effect. During the immersion period, half of the water was exchanged by fresh seawater daily, and SrCl2·6H2O were added to maintain constant concentration for each group. The exogenous Sr sedimentation in otoliths was detected by X-ray electron probe microanalyzer (EPMA). Results of line transect analysis showed that the strontium marking on otoliths could not be formed after the immersion of two concentrations (0.5 mg/L and 2 mg/L). The Sr high area appeared in the 8 mg/L concentration group with a 5.49-8.49 peak value, and the mean value of the Sr/Ca (Sr:Ca×1000) ratio was 4.50-6.60. Furthermore, in the 32 mg/L group, the mean value of the Sr/Ca ratio was 6.61±0.86, and the peak value of Sr was 5.62-11.04. This means that otoliths of can be marked with strontium by the method of SrCl2·6H2O immersion. However, in the 8 mg/L concentration group there were also unlabeled samples. and the mean value of Sr/Ca was lower than that of the 32 mg/L group. In the 32 mg/L group, the strontium marking rate was 100%, and the mean value of the Sr/Ca ratio was 6.61±0.86, which was significantly different ( < 0.05) compared with that of the control group. The EPMA mapping analysis showed that the red "high strontium marking ring" in the otolith appeared in the 8 mg/L group and 32 mg/L group, and the color of the "high strontium marking ring" was deepened with increasing of concentration. One-way analysis results showed that the total length and weight was not significantly different between the experimental groups and the control group (O immersion did not affect the growth of young fish. A Chi-square test ( > 0.05) showed there were no significant differences in mortality rate among the different concentration groups. Overall, 32 mg/L SrCl2·6H2O was the best marker concentration. 参考文献 相似文献 引证文献

Splitting resonance phenomenon of electromagnetic coupling effect for barium strontium titanate dielectric micro-spheres

The electromagnetic coupling effect of high refractive index barium strontium titanate dielectric micro-spheres array is investigated. The Mie resonance characteristics of electric and magnetic properties of sphere arrays are analyzed by varing independently the array periodicity. Specially, it was found that the splitting phenomenon of Mie magnetic and electric resonances was exhibited by the strong coupling between tightly arranged microspheres. Also, the resonance frequency and amplitude can be controlled by coupling strength. The local electromagnetic field distribution and the effective constitutive parameters of arrayed microspheres was calculated to verify the coupling effect and splitting resonance of the induced electric and magnetic dipoles.

Macroporous alginate foams crosslinked with strontium for bone tissue engineering

Nowadays, the need of novel strategies to repair and regenerate bone defects in the field of biomedical applications has increased. Novel approaches include the design of natural bioactive scaffolds mimicking bone tissue. These bioactive scaffolds have to possess biophysical properties suitable to address biological response towards newly bone tissue formation. In particular, scaffold porosity and pore size play a pivotal role in cell migration, adhesion and proliferation, thus increasing cell-material surface interaction and osteogenic signals transmission. Here we propose the development of macroporous alginate foams (MAFs) with porous and well interconnected structure, useful to enhance growth and osteogenic differentiation of human Mesenchymal Stem Cells (hMSCs). Moreover, in this study we report a new method for MAFs fabrication based on the combination of internal gelation technique with gas foaming. Strontium was employed in combination with calcium as cross-linking agent for the alginate chains and as enhancer of the osteogenic differentiation. The influence of strontium ions on the gelation kinetics, physical properties and degradation in physiological medium of MAFs was investigated. Our results suggest that the combination of internal gelation technique with gas foaming followed by freeze-drying is an easy and straightforward procedure to prepare alginate foams with high porosity and interconnectivity, able to support cell infiltration. Finally, biological assays showed how scaffolds with high strontium content are able to support cell growth and differentiation in long times by promoting osteogenic marker expression.

Plasma Strontium and Interactions between Calcium and Strontium for Type 2 Diabetes—A Hospital-Based Case-Control Study

Objective: Strontium and calcium play an essential role in bone metabolism but a paucity of epidemiological or experimental studies referring the role of strontium in the development type 2 diabetes (T2D). Prior studies have reported conflicting results for the relationships between plasma strontium and T2D. We therefore investigated the association between plasma strontium as well as the ratio of calcium to strontium (Ca/Sr) and newly diagnosed T2D. Methods: After propensity score matching for age and sex, 2,5newly-diagnosed T2D patients and 2,5controls with normal glucose tolerance were recruited in the case-control study. Plasma strontium and calcium levels were determined by inductively coupled plasma mass spectrometry (ICP-MS). Multivariate logistic regression analysis was used to evaluate the independent association of plasma strontium levels and Ca/Sr values with the likelihood of T2D. Results: Compared with the middle quintile, the multivariate-adjusted odds ratios (ORs) and 95% confidence intervals of T2D associated with the lowest quintile and the highest quintile of plasma strontium were 2.01 (1.66, 2.44) and 2.01 (1.65, 2.44), of plasma Ca/Sr were 2.11 (1.75, 2.54) and 2.01 (1.66, 2.43), respectively. In spline analysis, the U-shaped associations were consistently indicated, with the lowest odds of T2D at the plasma strontium concentration of 42.52 μg/L, and Ca/Sr value of 1500 approximately. We also discovered the pattern of high plasma calcium and low strontium level was associated with the highest odds of T2D, while the pattern of high plasma calcium and moderate to high strontium level was associated with the lowest odds of T2D. Conclusions: Our results suggested U-shaped associations between plasma strontium, Ca/Sr and T2D; both low and high levels of plasma strontium and Ca/Sr were associated with higher odds of newly diagnosed T2D. We should not only pay attention to calcium, but also to strontium and the homeostasis of the both. Disclosure L. Chen: None. Q. Wang: None. X. Hu: None. X. Wang: None. T. Sun: None. W. Bao: None. L. Liu: None.

Crystal Structure of Cl-Deficient Analogue of Taseqite from Odikhincha Massif

An eudialyte group mineral, found in pegmatites of the Odikhincha massif (the northern part of the Siberian platform), has been investigated using X-ray diffraction, IR spectroscopy, and Raman spectroscopy. The mineral is characterized by a high strontium content and a low chlorine content. It has a trigonal unit cell with the following parameters: a = 14.2700(6) A and c = 30.057(1) A; V = 5300.6(1) A3; sp. gr. R3m. The structure has been refined to R = 0.047 in the anisotropic approximation of atomic displacements using 1697F > 4σ(F). The idealized formula (Z = 3) was found to be Na12Sr2Ca6Fe 3 2+ Zr3NbSi25O72(OH,O)4Cl(Н2О)0.2. The chemical composition and structure of this mineral are close to those of taseqite; however, it differs from the holotype sample by a low chlorine content and peculiarities of cation distribution over basic structure sites. A comparative analysis of strontium-rich eudialytes has revealed their important crystallochemical feature: selective concentration of strontium in the N4 site. Thus, taseqite, along with heterophyllosilicates, may play a role of strontium concentrator in agpaitic pegmatites.

Multi-isotope evidence for cattle droving at Roman Worcester

Tooth enamel from six cattle mandibles excavated from Roman deposits at The Hive development site, Worcester (mid-2nd to early 4th century AD) was subjected to strontium, oxygen and carbon isotope analyses (87Sr/86Sr, δ18O and δ13C) to investigate the movement of cattle into Worcester, a purported regional cattle market, during the Roman period. Strontium isotope ratios show that none of the cattle were born and bred in close proximity to Worcester and arrived as mature beasts some time before death. Whilst two are consistent with origins in the region of Old Red Sandstone of Herefordshire to the west, the unusually high strontium isotope ratios of four of the cattle (i.e. >0.714) show that they originated in a region of ancient or radiogenic rocks such as granites which are found only in the west and north of Britain (e.g. Wales, the Lake District and northern Scotland) based on the currently available biosphere data. Comparison of the oxygen and carbon isotope values also suggests that the cattle were not from the same herd, but interpretation is complicated by the lack of comparative cattle data for the Roman period as well as other time periods. The severe wear of the molars from the aged cattle in this study also limits the interpretation of the results. More isotopic analyses are needed from other British sites in order to fully understand the implications of cattle movement into urban centres during the Roman period.

Improved non-destructive method for 90Sr activity determination in aqueous solutions using Monte Carlo simulation

The development of new methods and improvements of existing methods for the specific activity determination of 90Sr and other distinct beta emitters has been of considerable interest. The reason for this interest is that the notably small number of methods that are able to meet all the set criteria, such as reliability of the results, measurement uncertainty and time, and minimum production of radioactive waste, as well as applicability to various samples with reference to their nature, geometry and composition. In this paper, two methods for rapid 90Sr activity determination based on Monte Carlo simulations are used, one for a Si semiconductor detector for beta spectrometric measurements and the other for the Geiger-Muller (GM) ionization probe. To improve the reliability of the measurement results, samples with high and low strontium activity solutions were prepared in the form of dry residues. The results of the proposed methodology were verified with a standard method using a liquid scintillation counter, and notably good agreements are achieved.

Complexes of myo-inositol-hexakisphosphate (InsP6) with zinc or lanthanum to enhance excretion of radioactive strontium from the body.

90Sr, which was released into the atmosphere and the ocean following the Chernobyl and Fukushima Daiichi nuclear power plant disasters, is an important nuclear fission element. Compounds that inhibit the absorption of 90Sr into the bloodstream and enhance its elimination can be beneficial in decreasing the absorbed radiation dose in people exposed to 90Sr. Recently, we prepared complexes of myo-inositol-hexakisphosphate (InsP6) with zinc or lanthanum as decorporation agents. These complexes, called Zn-InsP6 and La-InsP6 respectively, are insoluble in water and can potentially chelate additional metal cations. Hypothesizing that these complexes can assist the excretion of 90Sr from the body, we evaluated them using 85Sr instead of 90Sr. In in vitro binding experiments, Zn-InsP6 showed higher strontium adsorption capacity than La-InsP6. We then performed in vivo biodistribution experiments of Zn-InsP6 in mice after oral administration of 85SrCl2. Mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity than mice in a non-treatment control group. Zn-InsP6 adsorbed radiostrontium in the gastrointestinal tract, inhibited this ion’s absorption into the bloodstream, and enhanced its excretion in the feces. Therefore, Zn-InsP6 appears to be a promising 90Sr “decorporation” agent.

Influence of differential diagenesis on primary depositional signals in limestone-marl alternations: An example from Middle Permian marine successions, South China

The diagenetic alteration of rhythmic successions remains one of the main challenges in paleoclimatology and cyclostratigraphy. To address this very important problem, thin sections and geochemical data of the limestone-marl alternations from Middle Permian carbonate successions in South China are examined to identify differential diagenetic effects in the petrography, organic and inorganic compositions, strontium concentrations and stable isotopic compositions of limestone beds and marl interlayers. In the Lengshuixi outcrop and the JY66-1 drill core, the most conspicuous features are that the limestone beds exhibit dense cementation, high strontium concentrations, negative oxygen isotopic values and positive carbon isotopic values. In contrast, the marl interlayers contain talc and exhibit strongly deformed and oriented bioclasts, low strontium concentrations, positive oxygen isotopic values and negative carbon isotopic values.Although differential diagenesis has occurred, some paleoclimate proxies (e.g., computed gamma-ray values) still preserve their primary signals and thus are suitable for cyclostratigraphic research. Eccentricity rhythm and millennial-scale rhythm are obviously recorded in Middle Permian limestone-marl alternations in South China. The variations in the oxygen and carbon isotopic values of limestone-marl alternations from different basins represent responses to different processes of differential diagenesis. This knowledge assumes that differential diagenesis occurs in diagenetically closed systems under the deep sea-floor. However, this assumption may not be valid in diagenetically open systems, where exotic fluids may add unexpected disturbances. Hence, it is crucial to understand diagenetic systems by determining the variations in strontium concentrations, which are as important as variations in carbon and oxygen isotopic values.

Treatment of Spent Nuclear Fuel for Separation, Immobilization and Disposal of Heat Generating High Level Fission Products, Caesium and Strontium

Separation of heat generating, high level fission product caesium and strontium from spent nuclear fuel boosts the capacity of waste repositories by as much as fifty times. For efficient use of already scarce repositories, separation of such fission products is mandatory. Separations of caesium and strontium using Chlorinated Cobalt Dicarbollide (CCD), PEG (Polyethylene Glycol), UNEX process and by Calixarenes or Fission Product Extraction Process (FPEX) were discussed. The UNEX method was then proposed as the most feasible method option. Following separation, nuclear waste immobilization techniques for such high-level fission product were discussed. The techniques included usage of concrete, glass and synthetic rock. Among them synthetic rock was identified as the most suitable one for immobilization of high-level nuclear waste. Finally, a safe disposal system with necessary required geology was shown for safe disposal of the waste.Journal of Chemical Engineering, Vol. 30, No. 1, 2017: 37-42