The purpose of this study was to characterize the individual effect of different cations (Ca(2+), Mg(2+), Na(+), K(+), and H(+)) on the acute toxicity of Cd to the earthworm Eisenia fetida. Higher activities of the co...
The purpose of this study was to characterize the individual effect of different cations (Ca(2+), Mg(2+), Na(+), K(+), and H(+)) on the acute toxicity of Cd to the earthworm Eisenia fetida. Higher activities of the considered cations increased the 48-h LC(50) (expressed as Cd(2+) activities) linearly to different extents in simulated soil solution. The conditional constants for the binding of H(+) (log K = 5.41), Cd(2+)(log K = 4.0), Ca(2+) (log K = 3.35), Mg(2+) (log K = 2.82), Na+(log K = 1.57), and K+(log K = 2.31) to the biotic ligand (BL) of E. fetida were derived from the toxicity data based on the biotic ligand model (BLM). Furthermore, it was calculated that on average 72% of the BL sites needed to be occupied by Cd(2+) to induce 50% lethal effect. Autovalidation of the model with the results of the test sets showed that 48-h LC(50) could be predicted within a factor of two.
A procedure for calculating cohesion parameters has been developed. Potentialities of the procedure, based on the analysis of topological partial structural factors, are exemplified by liquid tellurium. Isotropic and ...
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A procedure for calculating cohesion parameters has been developed. Potentialities of the procedure, based on the analysis of topological partial structural factors, are exemplified by liquid tellurium. Isotropic and anisotropic partial structural factors as well as functions of radial distribution of liquid tellurium atoms at 743 K and 843 K are calculated. The anisotropic structural factor is an interferometric function of a cluster of two two-atomic molecules with a period equal to covalent bond spacings. It is stated that, of Z atoms of the first coordination sphere in liquid tellurium at 743 K and 843 K, only two atoms follow the homeopolar type when interacting with the central atom, an the rest atoms result from the mutual penetration of isotropic distribution spheres. The method makes it possible to look into the nature of atomic interactions which specifies a short-range fine structure in a melt known as ″cohesion″ one.
The generation of human induced pluripotent stem cells (hiPSCs) represents an exciting advancement with promise for stem cell transplantation therapies as well as for neurological disease modeling. Based on the emergi...
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The generation of human induced pluripotent stem cells (hiPSCs) represents an exciting advancement with promise for stem cell transplantation therapies as well as for neurological disease modeling. Based on the emerging roles for astrocytes in neurological disorders, we investigated whether hiPSC-derived astrocyte progenitors could be engrafted to the rodent spinal cord and how the characteristics of these cells changed between in vitro culture and after transplantation to the in vivo spinal cord environment. Our results show that human embryonic stem cell- and hiPSC-derived astrocyte progenitors survive long-term after spinal cord engraftment and differentiate to astrocytes in vivo with few cells from other lineages present. Gene profiling of the transplanted cells demonstrates the astrocyte progenitors continue to mature in vivo and upregulate a variety of astrocyte-specific genes. Given this mature astrocyte gene profile, this work highlights hiPSCs as a tool to investigate disease-related astrocyte biology using in vivo disease modeling with significant implications for human neurological diseases currently lacking animal models.
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