Extreme ultraviolet emission lines of Ca XV in solar and laboratory spectra

New R-matrix calculations of electron impact excitation rates in Ca XV are used to derive theoretical electron density diagnostic emission line intensity ratios involving 2s(2)2p(2)- 2s2p(3) transitions, specifically R-1 = I(208.70 Angstrom)/I(200.98 Angstrom), R-2 = I(181.91 Angstrom)/I(200.98 Angstrom), and R-3 = I(215.38 Angstrom)/I(200.98 Angstrom), for a range of electron temperatures (T-e = 10(6.4)-10(6.8) K) and densities (Ne = 10(9)-10(13) cm(-3)) appropriate to solar coronal plasmas. Electron densities deduced from the observed values of R-1, R-2, and R-3 for several solar flares, measured from spectra obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, are found to be consistent. In addition, the derived electron densities are in excellent agreement with those determined from line ratios in Ca XVI, which is formed at a similar electron temperature to Ca XV. These results provide some experimental verification for the accuracy of the line ratio calculations, and hence the atomic data on which they are based. A set of eight theoretical Ca XV line ratios involving 2s(2)2p(2)-2s2p(3) transitions in the wavelength range similar to140-216 Angstrom are also found to be in good agreement with those measured from spectra of the TEXT tokamak plasma, for which the electron temperature and density have been independently determined. This provides additional support for the accuracy of the theoretical line ratios and atomic data.

Distribution of calcium (Ca) and magnesium (Mg) in the leaves of Brassica rapa under varying exogenous Ca and Mg supply

Background and Aims Leafy vegetable Brassica crops are an important source of dietary calcium (Ca) and magnesium (Mg) and represent potential targets for increasing leaf Ca and Mg concentrations through agronomy or breeding. Although the internal distribution of Ca and Mg within leaves affects the accumulation of these elements, such data are not available for Brassica. The aim of this study was to characterize the internal distribution of Ca and Mg in the leaves of a vegetable Brassica and to determine the effects of altered exogenous Ca and Mg supply on this distribution. Methods Brassica rapa ssp. trilocularis ‘R-o-18’ was grown at four different Ca:Mg treatments for 21 d in a controlled environment. Concentrations of Ca and Mg were determined in fully expanded leaves using inductively coupled plasma-mass spectrometry (ICP-MS). Internal distributions of Ca and Mg were determined in transverse leaf sections at the base and apex of leaves using energy-dispersive X-ray spectroscopy (EDS) with cryo-scanning electron microscopy (cryo-SEM). Key Results Leaf Ca and Mg concentrations were greatest in palisade and spongy mesophyll cells, respectively, although this was dependent on exogenous supply. Calcium accumulation in palisade mesophyll cells was enhanced slightly under high Mg supply; in contrast, Mg accumulation in spongy mesophyll cells was not affected by Ca supply. Conclusions The results are consistent with Arabidopsis thaliana and other Brassicaceae, providing phenotypic evidence that conserved mechanisms regulate leaf Ca and Mg distribution at a cellular scale. The future study of Arabidopsis gene orthologues in mutants of this reference B. rapa genotype will improve our understanding of Ca and Mg homeostasis in plants and may provide a model-to-crop translation pathway for targeted breeding.

Cobalt incorporation in calcite: Thermochemistry of (Ca,Co)CO3 solid solutions from density functional theory simulations

The incorporation of cobalt in mixed metal carbonates is a possible route to the immobilization of this toxic element in the environment. However, the thermodynamics of (Ca,Co)CO3 solid solutions are still unclear due to conflicting data from experiment and from the observation of natural ocurrences. We report here the results of a computer simulation study of the mixing of calcite (CaCO3) and spherocobaltite (CoCO3), using density functional theory calculations. Our simulations suggest that previously proposed thermodynamic models, based only on the range of observed compositions, significantly overestimate the solubility between the two solids and therefore underestimate the extension of the miscibility gap under ambient conditions. The enthalpy of mixing of the disordered solid solution is strongly positive and moderately asymmetric: calcium incorporation in spherocobaltite is more endothermic than cobalt incorporation in calcite. Ordering of the impurities in (0001) layers is energetically favourable with respect to the disordered solid solution at low temperatures and intermediate compositions, but the ordered phase is still unstable to demixing. We calculate the solvus and spinodal lines in the phase diagram using a sub-regular solution model, and conclude that many Ca1-xCoxCO3 mineral solid solutions (with observed compositions of up to x=0.027, and above x=0.93) are metastable with respect to phase separation. We also calculate solid/aqueous distribution coefficients to evaluate the effect of the strong non-ideality of mixing on the equilibrium with aqueous solution, showing that the thermodynamically-driven incorporation of cobalt in calcite (and of calcium in spherocobaltite) is always very low, regardless of the Co/Ca ratio of the aqueous environment.

Progression of Diet-Induced Diabetes in C57BL6J Mice Involves Functional Dissociation of Ca(2+) Channels From Secretory Vesicles

OBJECTIVE The aim of the study was to elucidate the cellular mechanism underlying the suppression of glucose-induced insulin secretion in mice fed a high-fat diet (HFD) for 15 weeks. RESEARCH DESIGN AND METHODS-C57BL6J mice were fed a HFD or a normal diet (ND) for 3 or 15 weeks. Plasma insulin and glucose levels in vivo were assessed by intraperitoneal glucose tolerance test. Insulin secretion in vitro was studied using static incubations and a perfused pancreas preparation. Membrane currents, electrical activity, and exocytosis were examined by patch-clamp technique measurements. Intracellular calcium concentration ([Ca(2+)](i)) was measured by microfluorimetry. Total internal reflection fluorescence microscope (TIRFM) was used for optical imaging of exocytosis and submembrane depolarization-evoked [Ca(2+)](i). The functional data were complemented by analyses of histology and gene transcription. RESULTS After 15 weeks, but not 3 weeks, mice on HFD exhibited hyperglycemia and hypoinsulinemia. Pancreatic islet content and beta-cell area increased 2- and 1.5-fold, respectively. These changes correlated with a 20-50% reduction of glucose-induced insulin secretion (normalized to insulin content). The latter effect was not associated with impaired electrical activity or [Ca(2+)](i) signaling. Single-cell capacitance and TIRFM measurements of exocytosis revealed a selective suppression (>70%) of exocytosis elicited by short (50 ms) depolarization, whereas the responses to longer depolarizations were (500 ms) less affected. The loss of rapid exocytosis correlated with dispersion of Ca(2+) entry in HFD beta-cells. No changes in gene transcription of key exocytotic protein were observed. CONCLUSIONS HFD results in reduced insulin secretion by causing the functional dissociation of voltage-gated Ca(2+) entry from exocytosis. These observations suggest a novel explanation to the well-established link between obesity and diabetes. Diabetes 59:1192-1201, 2010

Tetracaine stimulates insulin secretion through the mobilization of Ca2+ from thapsigargin- and IP3-insensitive Ca2+ reservoir in pancreatic beta-cells

The effect of tetracaine on Ca-45 efflux, cytoplasmic Ca2+ concentration [Ca2+](i), and insulin secretion in isolated pancreatic islets and beta-cells was studied. In the absence of external Ca2+, tetracaine (0.1-2.0 mM) increased the Ca-45 efflux from isolated islets in a dose-dependant manner. Tetracaine did not affect the increase in Ca-45 efflux caused by 50 mM K+ or by the association of carbachol (0.2 mM) and 50 mM K+. Tetracaine permanently increased the [Ca2+](i) in isolated beta-cells in Ca2+-free medium enriched with 2.8 mM glucose and 25 mu M D-600 (methoxiverapamil). This effect was also observed in the presence of 10 mM caffeine or 1 mu M thapsigargin. In the presence of 16.7 mM glucose, tetracaine transiently increased the insulin secretion from islets perfused in the absence and presence of external Ca2+. These data indicate that tetracaine mobilises Ca2+ from a thapsigargin-insensitive store and stimulates insulin secretion in the absence of extracellular Ca2+. The increase in Ca-45 efflux caused by high concentrations of K+ and by carbachol indicates that tetracaine did not interfere with a cation or inositol triphosphate sensitive Ca2+ pool in beta-cells.

Calcium in pre-laying and laying rations on the performance and quality of laying hens' eggshell

O ensaio experimental objetivou avaliação do efeito de diferentes níveis de cálcio (Ca) nas rações de pré-postura e postura sobre o desempenho e qualidade dos ovos de poedeiras comerciais. Foram alojadas 256 frangas da linhagem Hisex Brown com 16 semanas de idade em galpão convencional de postura. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 4 x 2 (4 níveis de cálcio - 0,8; 1,3; 1,8 e 2,3% na pré-postura e 2 níveis de cálcio - 2,5 e 3,5% na postura), totalizando oito tratamentos com quatro repetições de oito aves por unidade experimental. Iniciou-se com a ração de pré-postura às 16 semanas de idade das aves, sendo que a mesma foi fornecida até as aves atingiram 18 semanas de idade, quando então, iniciou-se com a ração de postura. Foram avaliadas durante quatro ciclos de 28 dias as seguintes variáveis: produção e peso dos ovos, consumo de ração, conversão alimentar, massa de ovos e qualidade da casca dos ovos. Através dos resultados obtidos pode-se concluir que um bom desempenho foi obtido com 0,8% de cálcio na fase de pré-postura. Na fase de postura o nível de 3,5% de cálcio promoveu maior peso de ovo e melhor qualidade de casca.

In vivo biological behavior of calcium phosphate cements with different Ca/P ratio

Bioceramics with different Ca/P ratio were prepared from a mechanical mixture of NaPO3, CaCO3, Ca(OH)2 and phosphate buffer solution and implanted in rats subcutaneous tissues. The cements were characterized by Thermo gravimetric analysis (TG-TDA), X-ray diffraction and 31P-NMR. The implant sites were excised after 1, 4 and 16 weeks, fixed, dehydrated, included in paraffin wax for serial cutting and examined under the light transmitted microscope. They were biocompatible and biodegradable when implanted in rat subcutaneous. None of the materials induced ectopic osteogenesis. According to the results, the studied materials seem to be able for manufacturing reabsorbable bone implants.

Dielectric and structural characterization of Pb1-xAxZr0.40Ti0.60O3 (A = Sr, Ca) ferroelectric ceramics

This paper reports the influence of Sr- and Ca-substitution on the structural and ferroelectric properties of Pb1-xSrxZr0.40Ti0.60O3 (PSZT) and Pb1-xCaxZr0.40Ti0.60O3 (PCZT) ceramic systems. The dielectric measurements show that these substitutions cause a diffuse behavior in the dielectric permittivity curves for all samples. According to the X-ray absorption near-edge structure (XANES) spectra collected at Ti K- and LIII-edge, when Pb was replaced by Sr or Ca, a decrease in the local distortion around Ti atoms in the TiO6 octahedron could be observed. The O K-edge XANES spectra also revealed that the hybridization between O 2p and Pb 6sp states decreased as the amount of Sr or Ca atoms increased. Based on these results, it was possible to ascertain that the ferroelectric behavior in PSZT and PCZT samples bears a close correlation to the hybridization weakening between O 2p and Pb 6 sp states. © 2013 by American Scientific Publishers.

Effect of calcium on the structural properties of Ba(1-x)Ca (x) TiO3 particles synthesized by complex polymerization method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Occurrence of Groundnut ringspot virus on Brazilian peanut crops

A high incidence of plants with mosaic, chlorotic spots, ringspots, necrosis, smaller leaves, and stunting was observed on peanut crops (Arachis hypogaea L.) in Itapolis, So Paulo State, Brazil. Transmission electron microscope examination of thin sections of infected leaves revealed the presence of spheroidal particles, ca. 80 nm in diameter, suggestive of Tospovirus. A DNA fragment of similar to 600 bp was amplified by RT-PCR from total RNA extracted from infected tissues using primers specific for the nucleocapsid gene of Groundnut ringspot virus (GRSV). Nucleotide and deduced amino acid sequences of the fragments showed high identities with known GRSV isolates.

The Banhado Alkaline Complex, Southeastern Brazil: source and evolution of potassic SiO2-undersaturated high-Ca and low-Ca magmatic series

The Cretaceous Banhado alkaline complex in southeastern Brazil presents two potassic SiO2-undersaturated series. The high-Ca magmatic series consist of initially fractionated olivine (Fo(92-91)) + diopside (Wo(48-43)En(49-35)Ae(0-7)), as evidenced by the presence of xenocrysts and xenoliths. In that sequence, diopside (Wo(47-38)En(46-37)Ae(0-8)) + phlogopite + apatite + perovskite (Prv(> 92)) crystallized to form the phlogopite melteigite and led to the Ca enrichment of the magma. Diopside (Wo(47-41)En(32-24) Ae(3-14)) continued to crystallize as an early mafic mineral, followed by nepheline (Ne(74.8-70.1)Ks(26.3-21.2)Qz(7.6-0.9)) and leucite (Lc(65-56)) and subsequently by melanite and potassic feldspar (Or(85-99)Ab(1-7)) to form melanite ijolites, wollastonite-melanite urtites and melanite-nepheline syenites. Melanite-pseudoleucite-nepheline syenites are interpreted to be a leucite accumulation. Melanite nephelinite dykes are believed to represent some of the magmatic differentiation steps. The low-Ca magmatic series is representative of a typical fractionation of aegirine-augite (Wo(36-29)En(25-4)Ae(39-18)) + alkali feldspar (Or(57-96)Ab(3-43)) + nepheline (Ne(76.5-69.0)Ks(19.9-14.4)Qz(15.1-7.7)) + titanite from phonolite magma. The evolution of this series from potassic nepheline syenites to sodic sodalite syenites and sodalitolites is attributed to an extensive fractionation of potassic feldspar, which led to an increase of the NaCl activity in the melt during the final stages forming sodalite-rich rocks. Phonolite dykes followed a similar evolutionary process and also registered some crustal assimilation. The mesocratic nepheline syenites showed interactions with phlogopite melteigites, such as compatible trace element enrichments and the presence of diopside xenocrysts, which were interpreted to be due to a mixing/mingling process of phonolite and nephelinite magmas. The geochemical data show higher TiO2 and P2O5 contents and lower SiO2 contents for the high-Ca series and different LILE evolution trends and REE chondrite-normalized patterns as compared to the low-Ca series. The Sr-87/Sr-86, Nd-143/Nd-144, Pb-206/Pb-204 and Pb-208/Pb-204 initial ratios for the high-Ca series (0.70407-0.70526, 0.51242-0.51251, 17.782-19.266 and 38.051-39.521, respectively) were slightly different from those of the low-Ca series (0.70542-0.70583, 0.51232-0.51240, 17.758-17.772 and 38.021-38.061, respectively). For both series, a CO2-rich potassic metasomatized lithospheric mantle enriched the source with rutile-bearing phlogopite clinopyroxenite veins. Kamafugite-like parental magma is attributed to the high-Ca series with major contributions from the melting of the veins. Potassic nephelinite-like parental magma is assigned to the low-Ca series, where the metasomatized wall-rock played a more significant role in the melting process.

Association of the (CA)n repeat polymorphism of insulin-like growth factor-I and -202 A/C IGF-binding protein-3 promoter polymorphism with adult height in patients with severe growth hormone deficiency

A number of mathematical models for predicting growth and final height outcome have been proposed to enable the clinician to 'individualize' growth-promoting treatment. However, despite optimizing these models, many patients with isolated growth hormone deficiency (IGHD) do not reach their target height. The aim of this study was to analyse the impact of polymorphic genotypes [CA repeat promoter polymorphism of insulin-like growth factor-I (IGF-I) and the -202 A/C promoter polymorphism of IGF-Binding Protein-3 (IGFBP-3)] on variable growth factors as well as final height in severe IGHD following GH treatment. DESIGN, PATIENTS AND CONTROLS: One hundred seventy eight (IGF-I) and 167 (IGFBP-3) subjects with severe growth retardation because of IGHD were studied. In addition, the various genotypes were also studied in a healthy control group of 211 subjects.

Intracellular Ca(2+) operates a switch between repair and lysis of streptolysin O-perforated cells

Pore-forming (poly)peptides originating from invading pathogens cause plasma membrane damage in target cells, with consequences as diverse as proliferation or cell death. However, the factors that define the outcome remain unknown. We show that in cells maintaining an intracellular Ca(2+) concentration [Ca(2+)](i) below a critical threshold of 10 microM, repair mechanisms seal off 'hot spots' of Ca(2+) entry and shed them in the form of microparticles, leading to [Ca(2+)](i) reduction and cell recovery. Cells that are capable of preventing an elevation of [Ca(2+)](i) above the critical concentration, yet are unable to complete plasma membrane repair, enter a prolonged phase of [Ca(2+)](i) oscillations, accompanied by a continuous shedding of microparticles. When [Ca(2+)](i) exceeds the critical concentration, an irreversible formation of ceramide platforms within the plasma membrane and their internalisation drives the dying cells beyond the 'point of no return'. These findings show that the extent of [Ca(2+)](i) elevation determines the fate of targeted cells and establishes how different Ca(2+)-dependent mechanisms facilitate either cell survival or death.

Short-term response of the Ca cycle of a montane forest in Ecuador to low experimental CaCl 2 additions

The tropical montane forests of the E Andean cordillera in Ecuador receive episodic Sahara-dust inputs particularly increasing Ca deposition. We added CaCl2 to isolate the effect of Ca deposition by Sahara dust to tropical montane forest from the simultaneously occurring pH effect. We examined components of the Ca cycle at four control plots and four plots with added Ca (2 × 5 kg ha–1 Ca annually as CaCl2) in a random arrangement. Between August 2007 and December 2009 (four applications of Ca), we determined Ca concentrations and fluxes in litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall, and fine litterfall and Al concentrations and speciation in soil solutions. After 1 y of Ca addition, we assessed fine-root biomass, leaf area, and tree growth. Only < 3% of the applied Ca leached below the acid organic layer (pH 3.5–4.8). The added CaCl2 did not change electrical conductivity in the root zone after 2 y. In the second year of fertilization, Ca retention in the canopy of the Ca treatment tended to decrease relative to the control. After 2 y, 21% of the applied Ca was recycled to soil with throughfall and litterfall. One year after the first Ca addition, fine-root biomass had decreased significantly. Decreasing fine-root biomass might be attributed to a direct or an indirect beneficial effect of Ca on the soil decomposer community. Because of almost complete association of Al with dissolved organic matter and high free Ca2+ : Al3+ activity ratios in solution of all plots, Al toxicity was unlikely. We conclude that the added Ca was retained in the system and had beneficial effects on some plants.

Does the educational success of children growing up in stepfamilies differ from children growing up in single parent households?

Within the framework of research into educational inequality, this paper focuses on the educational success of children who experience parental separation prior to the transition from primary into secondary education. Related to this, the first education passage following primary school is observed. The question arises as to whether children growing up in single parent households after parental separation and whether children in this category who in addition experienced the formation of a stepfamily differ from one another and from children growing up in “nuclear families” in regard to their scholastic performance and transition success. For that reason, not only scholastic performance (grades) but also the type of school attended following primary school are of particular interest. Furthermore, differences regarding parental educational decision-making are examined (vgl. Stocké 2007). The analyses are based on data from the longitudinal study "BIKS 8-14" (educational processes, competence development and selection decisions in preschool- and school age) that has been undertaken at the Otto Friedrich University in Bamberg.