47 resultados para Nehemiah 8:1-3
Resumo:
Five new compounds in the system (NH4)Cl/HgCl2/H2O have been obtained as colourless single crystals, (NH4)Hg5Cl11, (NH4)(2)Hg3Cl8(H2O), (NH4)(4)Hg3Cl10(H2O)(2), (NH4)(2)HgCl4(H2O), and (NH4)(10)Hg3Cl16. In all of these, as in HgCl2 itself, (almost) linear HgCl2 molecules persist with Hg-Cl distances varying from 229 to 236 pm. In (NH4)(10)Hg3Cl16 there are also tetrahedra [HgCl4] with d(Hg-Cl) = 247 pm present. If larger Hg-Cl distances (of up to 340 pm) are considered as belonging to the coordination sphere of Hg-II, the structures may be described as consisting of isolated octahedra and tetrahedra as in (NH4)(10)Hg3Cl16, edge-connected chains as in (NH4)(2)HgCl4(H2O), edge-connected chains and layers of octahedra as in (NH4)(4)Hg3Cl10(H2O)(2), corrugated layers of edge-connected octahedra as in (NH4)(2)Hg3Cl8(H2O), and, finally, a three-dimensional network of connected six- and seven-coordinate Hg-Cl polyhedra as in (NH4)Hg5Cl11. The water molecules are never attached to Hg-II. The (NH4)(+) cations, and sometimes Cl- anions, play a role for electroneutrality only.
Resumo:
This paper describes the use of molecular mechanics to model the geometry of the sodium complex of a calix[4] arene tetraester, in the 1,3-alternate conformation 1. Partial charges were assigned to the calixarene on the basis of semi-empirical (AM1, PM3, MNDO, INDO, CNDO and ZINDO) calculations and the binding of the sodium ion to the calixarene was modelled using molecular mechanics. Agreement between the optimised and X-ray structures of the complex was very good. The effect of placing the cation in different starting positions on the energy-minimised geometry of the complex is described.
Resumo:
Chiral enamides5f-i were found to react with pyrylium ylides to give cycloadducts 6d-i in good yields with an excellent level of stereoselectivity. The chiral auxiliary was successfully removed on hydrogenolysis of compound 6f in continuous flow (H-Cube) resulting in the first asymmetric synthesis of complex amine 8.
Resumo:
Epitaxial (001)-oriented 0.7Pb(Mg0.33Nb0.67)O3-0.3PbTiO3 (PMN-PT) thin films were deposited by pulsed laser deposition on vicinal SrTiO3 (001) substrates using La0.7Sr0.3MnO3 as bottom electrode. Detailed microstructural investigations of these films were carried out using X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Polarization-field hysteresis curves were measured at room temperature. Spontaneous polarization P s , remnant polarization P r and coercive voltage V c were found to be 25 μC/cm2, 15 μC/cm2 and 0.81 V, respectively. Field dependent dielectric constant measurements exhibited butterfly shaped curves, indicating the true ferroelectric nature of these films at room temperature. The dielectric constant and the dielectric loss at 100 kHz were found to be 238 and 0.14, respectively. The local piezoelectric properties of PMN-PT films were investigated by piezoelectric force microscopy and were found to exhibit a local piezoelectric coefficient of 7.8 pm/V.
Resumo:
This study explored the experiences of informal carers who were aged 65 years and over. It has been estimated that 15 per cent of those aged 65 or over provide some form of informal care in England. Despite a growing literature on the involvement of older people in research, there is a paucity of literature on the involvement of older carers. In this study, older carers were identified via a General Practice (GP) register in one urban medical practice. Data was collected through a series of focus groups, which were transcribed and analysed using
thematic analysis. Every carer aged 55 or over and registered with the medical practice was invited to take part in the study. Four female carers and one male carer took part in the study (age range 65-83). Themes that emerged during data analysis included, 1) managing things in an emergency, 2) feeling valued because they took part in the research and 3) the day-to-day reality of living with social exclusion. GP registers provide a valuable tool for identifying older
carers who may otherwise be difficult to engage in research. However, persuading GPs to engage with qualitative research may be a challenge.
Resumo:
Leukocyte-derived matrix metalloproteinases (MMP) are implicated in the tissue destruction characteristic of tuberculosis (TB). The contribution of lung stromal cells to MMP activity in TB is unknown. Oncostatin M (OSM) is an important stimulus to extrapulmonary stromal MMP induction, but its role in regulation of pulmonary MMP secretion or pathophysiology of TB is unknown. We investigated OSM secretion from Mycobacterium tuberculosis (Mtb)-infected human monocytes/macrophages and the networking effects of such OSM on lung fibroblast MMP secretion. Mtb increased monocyte OSM secretion dose dependently in vitro. In vivo tuberculous granulomas immunostained positively for OSM. Further, conditioned media from Mtb-infected monocytes (CoMTb) induced monocyte OSM secretion (670 ± 55 versus 166 ± 14 pg/mL in controls), implicating an autocrine loop. Mtb-induced OSM secretion was prostaglandin (PG) sensitive, and required activation of surface G-protein coupled receptors. OSM induction was ERK MAP kinase dependent, p38-requiring but JNK-independent. OSM synergized with TNF-, a key cytokine in TB granuloma formation, to stimulate pulmonary fibroblast MMP-1/-3 secretion, while suppressing secretion of tissue inhibitors of metalloproteinases-1/-2. In summary, Mtb infection of monocytes results in PG-dependent OSM secretion, which synergizes with TNF- to drive functionally unopposed fibroblast MMP-1/-3 secretion, demonstrating a previously unrecognized role for OSM in TB.
Resumo:
Simulations of beta-glucose in the ionic liquid 1,3-dimethylimidazoliurn chloride have been performed in order to examine the solvation environment of the carbohydrate. Both single molecule and 1:5 glucose:ionic liquid (16.7 wt %) solutions are Studied, and the hydrogen bonding between sugar and solvent is examined. The primary solvation shell around the perimeter of the glucose ring consists predominantly of chloride anions which hydrogen bond to the hydroxyl groups. A small presence of the cation is also found, with the association Occurring through the weakly acidic hydrogen at the 2-position of the imidazolium ring interacting with the oxygen atoms of the sugar secondary hydroxyls. An average chloride coordination number of 4 is found around the glucose for both the single molecule and high concentration Simulations, despite the reduced chloride:glucose ratio in the latter case. In relation to the cation, the glucose molecules occupy positions above and below the plane of the imidazolium ring. Importantly, even at high glucose concentrations, no significant change in the anion-cation interactions and overall liquid structure of the ionic liquid is found, indicating that the glucose is readily accommodated by the solvent at this concentration. Dominant contributions to the sugar-ionic liquid interaction energy come from favorable hydrogen bonding (electrostatic) interactions between hydroxyls and chlorides, although a small favorable van der Waals energy contribution is also seen between the sugar and cations suggesting that the cation could be tailored in order to further improve the dissolution of glucose/cellulose in ionic liquid systems.
A molecular dynamics study of glucose solvation in the ionic liquid 1,3-dimethylimidazolium chloride
Resumo:
Neutron diffraction has been used to determine the liquid structure of 1,3-dimethylimidazolium bis{( trifluoromethyl) sulfonyl} amide ([dmim][NTf2]). Significantly smaller charge ordering is found in this liquid compared with analogous chloride and hexafluorophosphate salts due to the diffuse charge density and size of the [NTf2](-) anion. This is manifested in a much larger cation-cation and cation-anion separation and an overlap of the cation-cation and cation-anion shells. Comparison of the liquid structure with the crystal structure reported by Holbrey et al. ( Dalton Trans. 2004, 2267) indicates little correlation, for example, the [NTf2](-) anion adopts a trans orientation predominantly in the liquid whereas a cis orientation is found in the solid phase.