578 research outputs found
Third Party Evaluation Model in Government Purchase of Home-Based Care Services and Its Improvement
Abstrac
Metal Amidoboranes and Their Derivatives for Hydrogen Storage
As potential hydrogen storage mediums, ammonia borane and its derivatives have been paid an increasing attention owing to their higher hydrogen capacities and facile dehydrogenation properties under moderate conditions. In this chapter, we presented extensive studies on thermodynamic tailoring of dehydrogenation of metal amidoboranes, metal borohydride-ammonia borane complexes, and metal amidoborane ammoniates as well as their derivatives, with special focus on the syntheses, crystal structures, and dehydrogenation properties. Finally, future perspective was given toward the practical applications
Telomere Recombination Accelerates Cellular Aging in Saccharomyces cerevisiae
Telomeres are nucleoprotein structures located at the linear ends of eukaryotic chromosomes. Telomere integrity is required for cell proliferation and survival. Although the vast majority of eukaryotic species use telomerase as a primary means for telomere maintenance, a few species can use recombination or retrotransposon-mediated maintenance pathways. Since Saccharomyces cerevisiae can use both telomerase and recombination to replicate telomeres, budding yeast provides a useful system with which to examine the evolutionary advantages of telomerase and recombination in preserving an organism or cell under natural selection. In this study, we examined the life span in telomerase-null, post-senescent type II survivors that have employed homologous recombination to replicate their telomeres. Type II recombination survivors stably maintained chromosomal integrity but exhibited a significantly reduced replicative life span. Normal patterns of cell morphology at the end of a replicative life span and aging-dependent sterility were observed in telomerase-null type II survivors, suggesting the type II survivors aged prematurely in a manner that is phenotypically consistent with that of wild-type senescent cells. The shortened life span of type II survivors was extended by calorie restriction or TOR1 deletion, but not by Fob1p inactivation or Sir2p over-expression. Intriguingly, rDNA recombination was decreased in type II survivors, indicating that the premature aging of type II survivors was not caused by an increase in extra-chromosomal rDNA circle accumulation. Reintroduction of telomerase activity immediately restored the replicative life span of type II survivors despite their heterogeneous telomeres. These results suggest that telomere recombination accelerates cellular aging in telomerase-null type II survivors and that telomerase is likely a superior telomere maintenance pathway in sustaining yeast replicative life span
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Nanorod Suprastructures from a Ternary Graphene Oxide-Polymer-CsPbX3 Perovskite Nanocrystal Composite That Display High Environmental Stability.
Despite the exceptional optoelectronic characteristics of the emergent perovskite nanocrystals, the ionic nature greatly limits their stability, and thus restricts their potential applications. Here we have adapted a self-assembly strategy to access a rarely reported nanorod suprastructure that provide excellent encapsulation of perovskite nanocrystals by polymer-grafted graphene oxide layers. Polyacrylic acid-grafted graphene oxide (GO-g-PAA) was used as a surface ligand during the synthesis of the CsPbX3 perovskite nanocrystals (NCs), yielding particles (5-12 nm) with tunable halide compositions that were homogeneously embedded in the GO-g-PAA matrix. The resulting NC-GO-g-PAA exhibits a higher photoluminescence quantum yield than previously reported encapsulated NCs while maintaining an easily tunable bandgap, allowing for emission spanning the visible spectrum. The NC-GO-g-PAA hybrid further self-assembles into well-defined nanorods upon solvent treatment. The resulting nanorod morphology imparts extraordinary chemical stability toward protic solvents such as methanol and water and much enhanced thermal stability. The introduction of barrier layers by embedding the perovskite NCs in the GO-g-PAA matrix, together with its unique assembly into nanorods, provides a novel strategy to afford robust perovskite emissive materials with environmental stability that may meet or exceed the requirement for optoelectronic applications
Ethyl 5-[(2,3-dimethyl-5-oxo-1-phenyl-2,5-dihydro-1H-pyrazol-4-yl)iminomethyl]-3,4-dimethyl-1H-pyrrole-2-carboxylate
In the title compound, C21H24N4O3, the molecule has an E configuration about the imine C=N double bond. Intermolecular N—H⋯O hydrogen bonds assemble molecules into centrosymmetric dimers
CT Experiments and Image Processing for the Water-Oil Displacement at Pore Scale
AbstractWe established a CT experimental method for the study of the water-oil displacement at pore scale. The microscopic core model made up of reservoir coring materials could truthfully reflect the surface property and pore structure of reservoir rocks. We scanned the core model at different water flooding stages using SkyScan1174v2 CT scanner, and high resolution images were obtained. The present paper adopted a new image segmentation method, which depends on the discriminatory analysis constrained by the measured porosity and oil saturation. This new method improved the accuracy of image segmentation. We utilized the new algorithm to carry out the segmentation of pores and residual oil from the scanning images. The segmentation results were in agreement with those measured from the core experiments
catena-Poly[[bis(pyridine-κN)zinc(II)]-μ-benzene-1,4-dicarboxylato-κ2 O 1:O 4]
In the title coordination polymer, [Zn(C8H4O4)(C5H5N)2]n, the ZnII atom, located on a twofold rotation axis, is tetracoordinated by two monodentate O atoms from two different carboxylate groups and two pyridyl N atoms, forming a distorted tetrahedral geometry. The ZnII atoms are bridged by terephthalate ligands, generating an infinite zigzag chain along [101]
catena-Poly[[(2,2′-bipyridine-κ2 N,N′)copper(I)]-μ-cyanido-κ2 C:N-[(2,2′-bipyridine-κ2 N,N′)copper(I)]-μ-thiocyanato-κ2 S:N]
The title compound, [Cu2(CN)(SCN)(C10H8N2)2]n, contains two crystallographically independent CuI atoms, each in a distorted tetrahedral geometry. Each Cu atom is coordinated by a bidentate chelating 2,2′-bipyridine ligand. A bridging cyanide anion links the two Cu(2,2′-bipyridine) units to form a binuclear unit. Adjacent binuclear units are connected by a thiocyanate anion into a one-dimensional helical chain along [010]. The cyanide anion is disordered, with each site occupied by both C and N atoms in an occupancy ratio of 0.61 (5):0.39 (5). The S atom of the thiocyanate anion is also disordered over two sites, with occupancy factors of 0.61 (3) and 0.39 (3). There are π–π interactions between the pyridyl rings of neighbouring chains [centroid–centroid distance = 3.82 (1) Å]
Aqua(2,2′-bipyrimidine-κ2 N,N′)(succinato-κ2 O 1,O 4)copper(II) dihydrate
In the crystal structure of the title compound, [Cu(C4H4O4)(C8H6N4)(H2O)]·2H2O, the CuII atom is chelated by a 2,2′-bipyrimidine (bpm) ligand and a succinate anion in the basal plane; a water molecule in the apical position completes the slightly distorted square-pyramidal coordination geometry. Another carboxylate O atom from an adjacent complex is located in the opposite apical direction, with a Cu⋯O distance of 2.706 (3) Å, and is not considered as a bridging atom. Extensive O—H⋯O and O—H⋯N hydrogen bonding is present in the crystal structure
Aquabis(2-amino-1,3-thiazole-4-acetato-κ2 O,N 3)nickel(II)
In the crystal structure of the title compound, [Ni(C5H5N2O2S)2(H2O)], the NiII cation is located on a twofold rotation axis and chelated by two 2-amino-1,3-thiazole-4-acetate (ata) anions in the basal coordination plane; a water molecule located on the same twofold rotation axis completes the distorted square-pyramidal coordination geometry. Intermolecular O—H⋯O and N—H⋯O hydrogen bonding, as well as π–π stacking between parallel thiazole rings [centroid–centroid distance 3.531 (8) Å], helps to stabilize the crystal structure
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