Chemical Bonding in Solids

This chapter discusses the various classes of hydride compounds, with a special focus on saline and metallic hydrides as well as oxyhydrides. It includes the following topics: thermodynamic stability, crystal chemistry, synthesis, and physical properties. The chapter also highlights recent progress in understanding hydride ion mobility in alkaline earth hydrides. It further deals with hydride compounds and in particular those containing alkali, alkaline earth, and transition and rare earth metals. The saline hydrides, that is, AH and AeH2 (with A=Li, Na, K, Rb, and Cs; Ae=Mg, Ca, Sr, and Ba) are proper ionic materials, in which hydrogen is present as hydride anions, H−. Saline hydrides show many similarities with their halide analogues, especially concerning crystal and electronic structures and, perhaps to a lesser extent, physical attributes such as brittleness, hardness, and optical properties

Rescue of heterochromatin organization in Hutchinson-Gilford progeria by drug treatment

Hutchinson-Gilford progeria (HGPS) is a premature aging syndrome associated with LMNA mutations. Progeria cells bearing the G608G LMNA mutation are characterized by accumulation of a mutated lamin A precursor (progerin), nuclear dysmorphism and chromatin disorganization. In cultured HGPS fibroblasts, we found worsening of the cellular phenotype with patient age, mainly consisting of increased nuclear-shape abnormalities, progerin accumulation and heterochromatin loss. Moreover, transcript distribution was altered in HGPS nuclei, as determined by different techniques. In the attempt to improve the cellular phenotype, we applied treatment with drugs either affecting protein farnesylation or chromatin arrangement. Our results show that the combined treatment with mevinolin and the histone deacetylase inhibitor trichostatin A dramatically lowers progerin levels, leading to rescue of heterochromatin organization and reorganization of transcripts in HGPS fibroblasts. These results suggest that morpho-functional defects of HGPS nuclei are directly related to progerin accumulation and can be rectified by drug treatment

Genetic assessment of the reproductive success of Atlantic salmon precocious parr by means of DNA-minisatellite loci.

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Bonding in Classical and Nonclassical Transition Metal Carbonyls: The Interacting Quantum Atoms Perspective

Chemical bonding in simple transition metal carbonyls is examined under the interacting quantum atoms approach (IQA), which provides an energetic viewpoint within the quantum theory of atoms in molecules (QTAIM). We have studied both classical and nonclassical isoelectronic series of complexes, with different coordinations and geometries and studied the evolution of the IQA interatomic interactions, using several levels of theory. Our results in classical carbonyls are compatible with the standard Dewar-Chatt-Duncanson model, although multicenter bonding may have an important role in some complexes. The increase (decrease) in the CO distance upon bonding is faithfully coupled to a decrease (increase) in the CO covalent energy, although the main energetic change in the CO moiety is electrostatic and due to charge transfer and/or polarization of its electron density. The metal-ligand interaction energy is dominated by covalent effects and depends strongly on the total net charge of the complex, being larger for negatively charged molecules, where π-back-donation is very important. The electrostatic (ionic-like) metal-ligand interaction energy is small in general, although it becomes more and more stabilizing with increasing coordination number. © 2010 American Chemical Society

Chemical Bonding in Solids

Abstract This chapter discusses the various classes of hydride compounds, with a special focus on saline and metallic hydrides as well as oxyhydrides. It includes the following topics: thermodynamic stability, crystal chemistry, synthesis, and physical properties. The chapter also highlights recent progress in understanding hydride ion mobility in alkaline earth hydrides. It further deals with hydride compounds and in particular those containing alkali, alkaline earth, and transition and rare earth metals. The saline hydrides, that is, AH and AeH2 (with A=Li, Na, K, Rb, and Cs; Ae=Mg, Ca, Sr, and Ba) are proper ionic materials, in which hydrogen is present as hydride anions, H−. Saline hydrides show many similarities with their halide analogues, especially concerning crystal and electronic structures and, perhaps to a lesser extent, physical attributes such as brittleness, hardness, and optical properties