Strontium

The present study reports in detail the LD50 determination in white mice of ICR strain from iv administration of barium in the form of chloride. The LD50 value was found to be 19.2 mg Ba2+/kg. The results for nitrate and acetate were close to chloride, but in Swiss-Webster strains these values were lower by a factor of almost 2. Further, LD50 values for Mg, Ca and Sr (using chlorides in ICR-mice) were 14.4, 42.4 and 147.6 mg/kg, respectively.

The introduction of stable isotopes in archaeological research beginning in the 1970s produced a revolution in the ways that several key anthropological issues were studied, including early hominin subsistence, hunter-gatherer spatial organization, origins and history of farming and pastoralist societies, migrations, and intra- and inter-group social differentiation. As a tool suited for the quantitative reconstruction of paleodiets, bone chemistry provided a new and independent line of evidence that was readily integrated into ongoing discussions based on archaeofaunal and paleobotanical data (see van der Merwe, 1982; Ambrose, 1993). The impact that isotopic research has had in the field of archaeology is reflected in the ever-growing number of publications making use of isotopic analyses, and in the also growing number of volumes directed towards the integration of available results and perspectives of analysis (Sillen & Armelagos, 1991; Sandford, 1993; Bocherens et al., 1999; Ambrose & Katzenberg, 2000; Ambrose & Krigbaum, 2003; Koch & Burton, 2003; Staller et al., 2007).
The archaeology of South America was part of this process, presenting some early and excellent examples of isotopic research focused on the resolution of archaeological problems (e.g. Hastorf & De Niro, 1985; Burger & van der Merwe, 1990; Ubelaker, et al., 1995). However, most of the abundant research conducted during the last two decades below 20° S of latitude is not well represented in the international archaeological literature (although see Fernández et al., 1999; Gil, 2003; Yesner et al., 2003; Falabella et al., 2008). In this context, one of the main goals of this volume is to provide an updated review of the isotopic research conducted in southern South America, including cases from the Bolivian and Argentinean Puna or “Altiplano”, northwestern Argentina, the central-western Andean region of Argentina, the Pampas, Patagonia, and the Atlantic and Pacific marine coastlines. This set of papers is the product of a Workshop named “Arqueología e Isótopos Estables en el Sur de Sudamérica: Discusión e Integración de Resultados” that was held in the city of Malargüe (Mendoza province, Argentina) in 2005. This workshop was organized in the memory of Susana Valencio, a geochemistry researcher who had a substantial role in the introduction of stable isotopes in Argentinean archaeology, and who died unexpectedly in 2004, leaving a great void among her many friends and colleagues.

Current lines of research
Food availability, preparation, and consumption are basic parts of ancient societies. This volume is focused on the southern cone of South America, where both agriculturalists and hunter-gatherers existed into modern times, and where stable isotope analysis has been widely used in recent times. Foremost is work related with the development of stronger approaches to regional isotopic ecology (Llano; Yacobaccio et al.), methodological aspects regarding the application of stable isotopes to the reconstruction of subsistence and migrations (Tykot et al.; Knudson), introduction and impact of agriculture on Andean societies (Calo & Cortés; Gil et al.; Laguens et al.), adoption of pastoralist economies (Izeta et al.), spatial organization and territoriality of hunter-gatherer groups from the Pampas and Patagonia (Berón et al.; Borrero et al.; Martínez et al.; Tessone et al.), and integration of isotopic and bioarchaeological data (Suby & Guichón). Overall, the systematic use of stable isotopes in archaeological research in South America has fostered a reevaluation of some widely held views regarding, among other important subjects, the importance of maize in Andean societies and the amplitude of hunter-gatherer home ranges.
Research conducted from South America usually has to cope with strong budget restrictions that may impose limits in the size of the available isotopic sample. This has been variously tackled by developing long-term projects that allow gradual increases in the amount of information produced, or by integrating international research teams that provide external funding sources. Both strategies are represented in this volume. We believe that an exploratory framework of research provides the most productive strategy – in this or any other academic context – where specific questions are pursued even when we know that the factual basis is far from ideal. The key aspect is to be sensitive to the paths that need to be followed in order to identify stronger patterns and suggest more accurate explanations. We are confident that the set of fourteen papers that make up this volume is successful in presenting original strategies to cope with old problems, as well as in raising questions not foreseen.
A main concern shared by these papers is the integration of isotopic data with other lines of evidence, including archaeofaunal studies, health conditions and paleopathology as inferred from human remains, lithic distributions, paleobotany, and mortuary practices. This is an important virtue that generates the need to evaluate several theoretical and methodological levels in order to integrate data differing in terms of units of analysis, resolution, and formation history. This task broadens the spectrum of the discussions developed, making them valuable beyond the limits of stable isotopic research and transcending the geographical scope of South America.

A 'critical metal' is one that has important economic uses, but which also faces supply risks for geopolitical or environmental and sustainability reasons. The constrained nature of critical metals supply means proposed solutions to the problem commonly involve reducing demand and therefore reliance, via recycling, substitution and thrifting. However, most critical metals are presently only small markets and therefore such an approach ignores the potential of transformational market growth to reduce supply risk, by creating large, diverse, transparent markets with multiple sources of primary mine supply, akin to modern base metals markets. Research is therefore required into which critical metals have the greatest potential for such transformational market growth. This study therefore conducts an evaluation of 49 critical metals to determine which are nearest to the combined breakthroughs in discovery, supply and demand that may lead to transformational market growth. The study concludes that 13 markets from the 49 critical metals, being magnesium, silicon, barium, boron, lithium, cobalt, chromium, vanadium, gallium, strontium, cerium, lanthanum and scandium have the highest potential for transformational market growth and thus efforts to resolve supply risk in these markets may be better focussed on overcoming current market constraints and growing these markets, rather than lessening reliance by reducing demand.

3D bioprinting of constructs for tissue engineering and regenerative medicine has steadily gained attention due to its potential to fabricate anatomically-precise living constructs, localise specific cell types and enable the regeneration of functional tissues in a clinical setting. However, the limited availability of bioinks that can be successfully 3D bioprinted with high fidelity and simultaneously provide encapsulated cells with a tailored, low-stiffness microenvironment supporting functional tissue formation remains an unmet challenge. To address both the physical and biological limitations of available bioinks, this study aimed to develop a nanocomposite bioink (Sr-GelMA) comprising of strontium-carbonate (Sr) nanoparticles and low concentration (5 w/v%) gelatin-methacryloyl (GelMA) hydrogel for extrusion-based 3D bioprinting of low-stiffness cell-laden scaffolds with high shape fidelity and bone-specific cell signalling factors. We systematically investigated the effect of Sr incorporation on hydrogel physico-chemical properties, print fidelity, scaffold shape retention, as well as cell viability, osteogenic differentiation and in vitro bone formation. Nanocomposite Sr-GelMA hydrogels retained their physical and mechanical properties, while rheological studies revealed a significant increase in viscosity profiles that led to notably enhanced printability compared to GelMA alone. Moreover, bioprinted Sr-GelMA scaffolds exhibited excellent shape fidelity evidenced by a defined pore geometry on the x-y-z axis, resulting in an interconnected bioink filament and pore network that was maintained even after long-term culture and osteogenic differentiation (28 days) of human mesenchymal stromal cells (hMSCs). The presence of clustered Sr nanoparticles in the cell-laden bioink allowed high quality bioprinting combined with high hMSC viability (>95%) post-fabrication. Furthermore, Sr addition resulted in enhanced osteogenic differentiation of hMSCs as revealed by higher alkaline phosphatase (ALP) levels, osteocalcin (OCN) and collagen type-I (Col I) expression, with mineralised nodule formation distributed homogenously throughout the bioprinted construct. This study demonstrated that strontium-based nanocomposite bioinks optimised for extrusion-based 3D bioprinting of osteoconductive scaffolds support long-term shape retention with promising potential for bone tissue regeneration.

In this study, effect of mechanical activation in planetary ball mill and disc mill, on carbothermic reduction of celestite ore with coke was investigated. Celestite ore (96% SrSO 4) from Sivas district was blended with excess metallurgical coke and mechanically activated for 1, 5, 15 and 45 min. Mechanically activated blends were analyzed by Particle Size Analyzer, Thermal Gravimetric Analyzer (TGA), Differential Scanning Calorimetric Analyzer (DSC), and X-Ray Diffractometer (XRD). The finest particles were obtained at 45 min disc milling, of which d50 was 1.30 µm. TGA and DSC analyses showed that the reaction temperature was decreasing from 973°C to 892°C, by 1 min disc milling and 45 min planetary ball milling, respectively. XRD peaks broadened and peak intensities decreased by extending the mechanical activation time in both type of milling processes. All of the mechanically activated powders were roasted at 900, 1000, and 1100°C. According to XRD analyses; it is possible to see some peaks of strontium sulphide (SrS) after roasting at 900 and 1000°C, however, at 1100°C carbide formation is obtained.

The present study was aimed at investigating the co-substitution of sodium and carbonate in strontium hydroxyfluorapatites because these compounds have many similarities to the mineral phase of bones. Herein, three series of sodium-and carbonate-doped strontium hydroxyfluorapatites were prepared via a co-precipitation method. Chemical analysis via inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), Rietveld refinement, Fourier transform infrared spectroscopy (FTIR), 31 P nuclear magnetic resonance (NMR), and differential and gravimetric thermal analysis (DTA–GTA) characterizations were employed for the identification of the obtained products. Sodium-and fluoride-doped strontium hydroxyapatite was found to be a pure apatitic phase containing ionic vacancies. Rietveld analysis showed a significant decrease in the a lattice parameter as sodium and fluoride levels increased, whereas in carbonate-and fluoride-doped strontium hydroxyapatite, both the a and the c lattice parameters decreased as the amounts of carbonate that were added increased. The obtained powders were a B-type carbonate apatite with vacancies. The co-substitution of sodium and carbonate in the hydroxyfluorapatite structure typically gave rise to B-type carbonate apatite with vacancies. Thermal investigation in the range of 500–1200 1C revealed that decomposition occurred at a temperature of about 800 1C, and Sr 3 (PO 4) 2 was formed.

Zn2+ increased the rate of spontaneous release of catecholamines from bovine adrenal glands. This effect was Ca2+ independent; in fact, in the absence of extracellular Ca2+, the secretory effects of Zn2+ were enhanced. At low concentrations (3–10 μM), Zn2+ enhanced the secretory responses to 10-s pulses of 100 μM 1,1-dimethyl-4-phenylpiperazinium (DMPP, a nicotinic receptor agonist) or 100 mM K+. In the presence of DMPP, secretion was increased 47% above controls and in high-K+ solutions, secretion increased 54% above control. These low concentrations of Zn2+ did not facilitate the whole-cell Ca2+ (I Ca) or Ba2+ (I Ba) currents in patch-clamped chromaffin cells. Higher Zn2+ concentrations inhibited the currents (IC50 values, 346 μM for I Ca and 91 μM for I Ba) and blocked DMPP- and K+-evoked secretion (IC50 values, 141 and 250 μM, respectively). Zn2+ permeated the Ca2+ channels of bovine chromaffin cells, although at a much slower rate than other divalent cations. Peak currents at 10 mM Ba2+, Ca2+, Sr2+ and Zn2+ were 991, 734, 330 and 7.4 pA, respectively. Zn2+ entry was also evidenced using the fluorescent Ca2+ probe fura-2. This was possible because Zn2+ causes an increase in fura-2 fluorescence at the isosbestic wavelength for Ca2+, i.e. 360 nm. There was a slow resting entry of Zn2+ which was accelerated by stimulation with DMPP or high-K+ solution. The entry of Zn2+ was concentration dependent, slightly antagonized by 1 mM Ca2+ and completely blocked by 5 mM Ni2+. The entry of Ca2+ evoked by depolarization with high-K+ solution was antagonized by Zn2+. We conclude that inhibition by Zn2+ of evoked catecholamine secretion is associated with blockade of Ca2+ entry through Ca2+ channels recruited by DMPP or K+. However, the facilitation of secretion observed at low Zn2+ concentrations, or in the absence of Ca2+, may be exerted at an intracellular site on the secretory machinery. This is plausible because Zn2+ permeates the bovine chromaffin cell Ca2+ channels and in this way gains access to the cytosol. In addition, we have established conditions for measuring Zn2+ transients in fura-2-loaded cells with a very high sensitivity, taking advantage of the high-affinity binding of Zn2+ to fura-2 and the modification of its fluorescence spectrum.

Herein, we rigorously develop novel 3-dimensional algebraic models called Genetic Hotels of the Standard Genetic Code (SGC). We start by considering the primeval RNA genetic code which consists of the 16 codons of type RNY (purine-any base-pyrimidine). Using simple algebraic operations, we show how the RNA code could have evolved toward the current SGC via two different intermediate evolutionary stages called Extended RNA code type I and II. By rotations or translations of the subset RNY, we arrive at the SGC via the former (type I) or via the latter (type II), respectively. Biologically, the Extended RNA code type I, consists of all codons of the type RNY plus codons obtained by considering the RNA code but in the second (NYR type) and third (YRN type) reading frames. The Extended RNA code type II, comprises all codons of the type RNY plus codons that arise from transversions of the RNA code in the first (YNY type) and third (RNR) nucleotide bases. Since the dimensions of remarkable subsets of the Genetic Hotels are not necessarily integer numbers, we also introduce the concept of algebraic fractal dimension. A general decoding function which maps each codon to its corresponding amino acid or the stop signals is also derived. The Phenotypic Hotel of amino acids is also illustrated. The proposed evolutionary paths are discussed in terms of the existing theories of the evolution of the SGC. The adoption of 3-dimensional models of the Genetic and Phenotypic Hotels will facilitate the understanding of the biological properties of the SGC.

Four agricultural wastes: 1) castor bean leaves (CBL), 2) castor bean capsules (CBC), 3) jojoba leaves (JL), and 4) jojoba capsules (JC), were used as adsorbents for the adsorption of Strontium (Sr) from Abu Zaabal industrial wastewater. Three different dosages (0, 0.5, and 1g /100ml wastewater) were used for each at different contact times (1h., 2h., 3h, and 24h). The data showed that: 1) the concentration of Sr in Abu Zaabal industrial wastewater was high (9.8 mg/L), 2) the concentration of Sr has declined overtime and with the use of high dosage of bio-sorbents, 3) the maximum Sr (II) adsorption percentage was observed by using jojoba capsules wastes at 1% dosage and at 24 hours contact time (48.1%).While the lowest percentages were recorded by using castor leaves at 0.5% for 1 and 3 hours of contact time (1.6 and 1.2%). The data also showed that jojoba leaves at concentration 1% recorded the highest adsorption percentage (78%) for Cd. Castor bean and jojoba wastes were found to be attractive low cost materials for the treatment of industrial wastewater to remove Sr and Cd. Get more articles at: http://www.innspub.net/volume-5-number-5-november-2014-jbes/

Dogs were frequently employed as laboratory subjects during the era of atomic bomb testing (1950–1980), particularly in studies used to generate predictive data regarding the expected effects of accidental human occupational exposure to radiation. The bulk of these studies were only partly reported in the primary literature, despite providing vital information regarding the effects of radiation exposure on a model mammalian species. Herein we review this literature and summarize the biological effects in relation to the isotopes used and the method of radionuclide exposure. Overall, these studies demonstrate the wide range of developmental and physiological effects of exposure to radiation and radionuclides in a mid‐sized mammal.