951 resultados para Li, Jiang
Resumo:
Three-dimensional ordered mesoporous (3DOM) ZnCo2O4 materials have been synthesized via a hard template and used as bifunctional electrocatalysts for rechargeable Li-O2 batteries. The as-prepared ZnCo2O4 nanoparticles possess a high specific surface area of 127.2 m2 g-1 and a spinel crystalline structure. The Li-O2 battery utilizing 3DOM ZnCo2O4 shows a higher specific capacity of 6024 mAh g-1 than that with pure Ketjen black (KB). Moreover, the ZnCo2O4-based electrode enables much enhanced cyclability with a smaller discharge-recharge voltage gap than that of the carbon-only cathode. Such excellent catalytic performance of ZnCo2O4 could be associated with its larger surface area and 3D ordered mesoporous structure
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Li-rich materials are considered the most promising for Li-ion battery cathodes, as high capacity can be achieved. However, poor cycling stability is a critical drawback that leads to poor capacity retention. Here a strategy is used to synthesize a large-grain lithium-rich layered oxides to overcome this difficulty without sacrificing rate capability. This material is designed with micron scale grain with a width of about 300 nm and length of 1-3 μm. This unique structure has a better ability to overcome stress-induced structural collapse caused by Li-ion insertion/extraction and reduce the dissolution of Mn ions, which enable a reversible and stable capacity. As a result, this cathode material delivered a highest discharge capacity of around 308 mAh g-1 at a current density of 30 mA g-1 with retention of 88.3% (according to the highest discharge capacity) after 100 cycles, 190 mAh g-1 at a current density of 300 mA g-1 and almost no capacity fading after 100 cycles. Therefore, Lithium-rich material of large-grain structure is a promising cathode candidate in Lithium-ion batteries with high capacity and high cycle stability for application. This strategy of large grain may furthermore open the door to synthesize the other complex architectures for various applications.
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A three-dimensional (3D) graphene-Co3O4 electrode was prepared by a two-step method in which graphene was initially deposited on a Ni foam with Co3O4 then grown on the resulting graphene structure. Cross-linked Co3O4 nanosheets with an open pore structure were fully and vertically distributed throughout the graphene skeleton. The free-standing and binder-free monolithic electrode was used directly as a cathode in a Li-O2 battery. This composite structure exhibited enhanced performance with a specific capacity of 2453 mA h g-1 at 0.1 mA cm-2 and 62 stable cycles with 583 mA h g-1 (1000 mA h gcarbon-1). The excellent electrochemical performance is associated with the unique architecture and superior catalytic activity of the 3D electrode.
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A novel strategy for the controlled synthesis of 2D MoS<inf>2</inf>/C hybrid nanosheets consisting of the alternative layer-by-layer interoverlapped single-layer MoS<inf>2</inf> and mesoporous carbon (m-C) is demonstrated. Such special hybrid nanosheets with a maximized MoS<inf>2</inf>/m-C interface contact show very good performance for lithium-ion batteries in terms of high reversible capacity, excellent rate capability, and outstanding cycling stability.
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The time-dependent close-coupling method is used to calculate electron-impact excitation cross sections for the Li(2s)--{\textgreater}Li(nl) and Li(2p)--{\textgreater}Li(nl) transitions at incident energies just above the ionization threshold. The implementation of the time-dependent close-coupling method on a nonuniform lattice allows the study of continuum-coupling effects in excitations to high principal quantum number, i.e., n{\textless}=10. Good agreement is found with R-matrix with pseudostates calculations, which also include continuum-coupling effects, for excitations to low principal quantum number, i.e., n{\textless}=4. Poor agreement is found with standard distorted-wave calculations for excitations to all principal quantum numbers, with differences still at the 50% level for n=10. We are able to give guidance as to the accuracy expected in the n3 extrapolation of nonperturbative close-coupling calculations of low n cross sections and rate coefficients.
Resumo:
Electron-impact ionization cross sections for the 1s2s 1S and 1s2s 3S metastable states of Li+ are calculated using both perturbative distorted-wave and non-perturbative close-coupling methods. Term-resolved distorted-wave calculations are found to be approximately 15% above term-resolved R-matrix with pseudostates calculations. On the other hand, configuration-average time-dependent close-coupling calculations are found to be in excellent agreement with the configuration-average R-matrix with pseudostates calculations. The non-perturbative R-matrix and close-coupling calculations provide a benchmark for experimental studies of electron-impact ionization of metastable states along the He isoelectronic sequence.
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A first stage collision database is assembled which contains electron-impact effective collision strengths, and ionization and recombination rate coefficients for Li, Li+, and Li2+. The first stage database is constructed using the R-matrix with pseudo-states, time-dependent close-coupling, converged close-coupling, and perturbative distorted-wave methods. A second stage collision database is then assembled which contains generalized collisional-radiative and radiated power loss coefficients. The second stage database is constructed by solution of collisional-radiative equations in the quasi-static equilibrium approximation using the first stage database. Both collision database stages reside in electronic form at the ORNL Controlled Fusion Atomic Data Center and in the ADAS database, and are easily accessed over the worldwide internet. ?? 2006 Elsevier Inc. All rights reserved.
Resumo:
Korean mondshood root polysaccharides (KMPS) isolated from the root of Aconitum coreanum (Lévl.) Rapaics have shown anti-inflammatory activity, which is strongly influenced by their chemical structures and chain conformations. However, the mechanisms of the anti-inflammatory effect by these polysaccharides have yet to be elucidated. A RG-II polysaccharide (KMPS-2E, Mw 84.8 kDa) was isolated from KMPS and its chemical structure was characterized by FT-IR and NMR spectroscopy, gas chromatography–mass spectrometry and high-performance liquid chromatography. The backbone of KMPS-2E consisted of units of [→6) -β-D-Galp (1→3)-β-L-Rhap-(1→4)-β-D-GalpA-(1→3)-β-D-Galp-(1→] with the side chain →5)-β-D-Arap (1→3, 5)-β-D-Arap (1→ attached to the backbone through O-4 of (1→3,4)-L-Rhap. T-β-D-Galp is attached to the backbone through O-6 of (1→3,6)-β-D-Galp residues and T-β-D-Ara is connected to the end group of each chain. The anti-inflammatory effects of KMPS-2E and the underlying mechanisms using lipopolysaccharide (LPS) - stimulated RAW 264.7 macrophages and carrageenan-induced hind paw edema were investigated. KMPS-2E (50, 100 and 200 µg/mL) inhibits iNOS, TLR4, phospho-NF-κB–p65 expression, phosphor-IKK, phosphor-IκB-α expression as well as the degradation of IκB-α and the gene expression of inflammatory cytokines (TNF-α, IL-1β, iNOS and IL-6) mediated by the NF-κB signal pathways in macrophages. KMPS-2E also inhibited LPS-induced activation of NF-κB as assayed by electrophorectic mobility shift assay (EMSA) in a dose-dependent manner and it reduced NF-κB DNA binding affinity by 62.1% at 200µg/mL. In rats, KMPS-2E (200 mg/kg) can significantly inhibit carrageenan-induced paw edema as ibuprofen (200 mg/kg) within 3 h after a single oral dose. The results indicate that KMPS-2E is a promising herb-derived drug against acute inflammation.
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One of the global targets for non-communicable diseases is to halt, by 2025, the rise in the age-standardised adult prevalence of diabetes at its 2010 levels. We aimed to estimate worldwide trends in diabetes, how likely it is for countries to achieve the global target, and how changes in prevalence, together with population growth and ageing, are affecting the number of adults with diabetes. We pooled data from population-based studies that had collected data on diabetes through measurement of its biomarkers. We used a Bayesian hierarchical model to estimate trends in diabetes prevalence-defined as fasting plasma glucose of 7.0 mmol/L or higher, or history of diagnosis with diabetes, or use of insulin or oral hypoglycaemic drugs-in 200 countries and territories in 21 regions, by sex and from 1980 to 2014. We also calculated the posterior probability of meeting the global diabetes target if post-2000 trends continue. We used data from 751 studies including 4,372,000 adults from 146 of the 200 countries we make estimates for. Global age-standardised diabetes prevalence increased from 4.3% (95% credible interval 2.4-7.0) in 1980 to 9.0% (7.2-11.1) in 2014 in men, and from 5.0% (2.9-7.9) to 7.9% (6.4-9.7) in women. The number of adults with diabetes in the world increased from 108 million in 1980 to 422 million in 2014 (28.5% due to the rise in prevalence, 39.7% due to population growth and ageing, and 31.8% due to interaction of these two factors). Age-standardised adult diabetes prevalence in 2014 was lowest in northwestern Europe, and highest in Polynesia and Micronesia, at nearly 25%, followed by Melanesia and the Middle East and north Africa. Between 1980 and 2014 there was little change in age-standardised diabetes prevalence in adult women in continental western Europe, although crude prevalence rose because of ageing of the population. By contrast, age-standardised adult prevalence rose by 15 percentage points in men and women in Polynesia and Micronesia. In 2014, American Samoa had the highest national prevalence of diabetes (>30% in both sexes), with age-standardised adult prevalence also higher than 25% in some other islands in Polynesia and Micronesia. If post-2000 trends continue, the probability of meeting the global target of halting the rise in the prevalence of diabetes by 2025 at the 2010 level worldwide is lower than 1% for men and is 1% for women. Only nine countries for men and 29 countries for women, mostly in western Europe, have a 50% or higher probability of meeting the global target. Since 1980, age-standardised diabetes prevalence in adults has increased, or at best remained unchanged, in every country. Together with population growth and ageing, this rise has led to a near quadrupling of the number of adults with diabetes worldwide. The burden of diabetes, both in terms of prevalence and number of adults affected, has increased faster in low-income and middle-income countries than in high-income countries. Wellcome Trust.
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Commençant par : «... voluntez d'Elinde et landemain quant il fut ajornez... » et finissant par : «... et plairai tant com li mondes durrai, li quex est apelez li Livres dou Bret. Explicit li Livres dou Bret. Amen » . D'après l'épilogue, « HELYE DE BERRON » aurait remanié le travail de LUCE DU GAST, qu'il a divisé en trois livres. Voir l'introduction au livre III, fol. 264. Manque le premier feuillet de chaque livre.
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Début : « Si povés vous savoir les sains leus de la terre... — Fin : «... Adonc estoient l'an de l'incarnation Nostre Seigneur mil CCLXI. Explicit les Feiz d'Outremer. Ce livre ci fu complet d'escripture l'an de l'incarnation Nostre Seigneur mil trois cens et trante et VII, le jeudi devant la feste mon seigneur saint Thomas l'apostre devant Noël. » — Nombreuses miniatures. — Au fol. 1, on lit : « Au duc d'Arschot en 1584 ».
Resumo:
Commencement : « A la veille de la Pentecouste quant li compaignon de la Table reonde furent venu a Chamahelot... » — Fin : « ...Et quand Boors ot conté les aventures del S. Graal, teles com il les avoit veu, si furent mises en escript et gardées moult chierement, dont mestres Gautiers Map le traist a faire sen livre del Graal pour l'amour del roy Henri son signour, qui fist l'hystoire translater de latin en franchois. Si s'en taist atant li contes que plus n'en dist des aventures del S. Graal. Amen. — Chius livres fu parescrips le nuit Nostre Dame en mi aoust l'a[n] mil trois cens et LI : si l'escripst Pierars dou Tielt, et enlumina et loia. — Explicit li queste del S. Graal. » Fol. 95 : Annales depuis le commencement du monde jusqu'en 1281. Commencement : « Chi conmencent li an dés le conmencement del monde tres chi qu'en nos temps... » — Fin : « M. CC. LXXIX. Margerite contesse de Flandres et de Hainau moru. Guis ses fieus fu quens. — MCCLXXX. Nicolas pape morut. — MCCLXXXI. Martins fu pape. »
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Commencement : « Or dist li contes que li rois Melyadus demoura ou chastel... » — Fin : « ...et encore est communement son nom par toute Engleterre. — Cy fine le tiers et derrenier livre de Guiron le Courtois. »
« Li Abrejance de l'ordre de chevalerie... par... VEGECE FLAIVE », traduction par « JEHAN PRIORAT ».
Resumo:
Commençant par : « Li premiers livres nos ensoingne, Vegeces Flaives le tesmoingne... » et finissant par : « Que Dex le traie à bone fin. Ici mon livre vos defin. Amen. Expliciz li romanz de chevalerie » .