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1.
Phys Chem Chem Phys ; 19(48): 32708-32714, 2017 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-29199287

RESUMO

Lithium-sulfur (Li-S) batteries have attracted increasing attention due to their high theoretical capacity, being a promising candidate for portable electronics, electric vehicles and large-scale energy storage. The interactions of bilayer structured graphitic C3N4 (bi-C3N4) with S8, lithium polysulfides (LiPSs), 1,3-dioxolane, 1,2-dimethoxyethane and tetrahydrofuran ether-based solvents have been studied using first-principles calculations. It has been found that the (micropore-scale) interlayer of bi-C3N4 shows intimate contact and strong binding with S8 and LiPSs due to the formation of chemical Li-N bonds. The incorporation of soluble LiPSs by the wrinkled layers of bi-C3N4 with 5.5-7.2 Å interlayer pores can suppress the shuttling effect. The interlayer ultramicropores with interlayer distances of <4 Å can accommodate the small Li2S2 and Li2S molecules, and impede the irreversible reaction between the solvents and the LiPSs. The calculated energy gap of bi-C3N4 decreases to be narrow during lithiation. Our results can provide a guideline for promoting the electrochemical performance of microporous g-C3N4/sulfur composites for Li-S batteries.

2.
Nanotechnology ; 27(36): 365604, 2016 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-27482737

RESUMO

Though possessing low absorption throughout a wide infrared (IR) spectral regime, owing to a high refractive index, zinc selenide substrates are generally covered by antireflection coatings (ARCs) for practical optical uses. However, achieving a high transmission of ZnSe substrates in the near-IR (NIR) region is still challenging. Herein, for the first time, colloidal ZnSe hollow nanospheres (HNSs) smaller than 100 nm were prepared and adopted to assemble ARCs for ZnSe substrates. The voiding kinetics of the HNSs was found to agree well with the nanoscale Kirkendall effect, and the self-diffusion of the Zn ion in the core was faster than its diffusion through the ZnSe shell. With single-index ARCs, the transmission of ZnSe substrates was remarkably enhanced in the NIR region, with up to an 18% increase at 840 nm. Besides, the ZnSe HNS-based ARCs showed superior mechanical stability even under violent ultrasonication in organic solutions. We expect that ZnSe HNSs will make it possible to construct graded-index ARCs to realize omnidirectional and broadband antireflection in IR, through further tuning of HNSs' void fraction.

3.
Neurochem Res ; 40(9): 1954-65, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26285901

RESUMO

Magnesium lithospermate B (MLB) is one of the major bioactive components of Radix Salviae miltiorrhizae, a Chinese traditional herbal medicine colloquially known as Dan Shen. In this study, we investigated the neuroprotective effect of MLB against oligomeric amyloid ß (Aß) (1-42)-induced neurotoxicity in cultured FVB mouse hippocampal neurons. We found that pretreatment with MLB not only prevents a loss in neuronal cell viability following exposure to Aß (1-42), but also attenuates Aß (1-42)-induced release of pro-inflammatory cytokines and neuronal apoptosis in a dose-dependent manner. Mechanistic studies show that MLB counteracts Aß (1-42)-induced activation of the nuclear factor kappa B (NF-κB) pathway, evidenced by the suppression of NF-κB luciferase reporters, decreased expression of phosphorylated Inhibitor κB α and IκB kinase α, and reduced nuclear translocation of p65 in response to pre-treatment with 50 µg/ml MLB prior to Aß (1-42) exposure. MLB was able to reverse the increase in phosphorylated c-Jun N-terminal kinase (JNK) levels as well as the decrease in phosphorylated Akt levels that are induced by Aß (1-42), although this finding did not extend to extracellular signal-regulated kinase or p38 kinases. Furthermore, combining MLB with the JNK inhibitor SP600125 synergistically counteracts the Aß (1-42)-induced reduction in cell viability and neurite growth, and the neuroprotective effects of MLB could be attenuated by the Akt inhibitor triciribine. In conclusion, these results suggest that MLB can protect against Aß (1-42)-induced neuronal damage, which is most likely to be mediated by the NK-κB pathway.


Assuntos
Peptídeos beta-Amiloides/toxicidade , Medicamentos de Ervas Chinesas/farmacologia , NF-kappa B/metabolismo , Neurônios/efeitos dos fármacos , Fragmentos de Peptídeos/toxicidade , Animais , Apoptose/efeitos dos fármacos , Ativação Enzimática , MAP Quinase Quinase 4/metabolismo , Camundongos
4.
J Exp Bot ; 55(398): 939-49, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15020645

RESUMO

In order to understand the salt-tolerance mechanism of alkali grass (Puccinellia tenuiflora) compared with wheat (Triticum aestivum L.), [K(+)] and [Na(+)] in roots and shoots in response to salt treatments were examined with ion element analysis and X-ray microanalysis. Both the rapid K(+) and Na(+) influx in response to different NaCl and KCl treatments, and the accumulation of K(+) and Na(+) as the plants acclimated to long-term stress were studied in culture- solution experiments. A higher K(+) uptake under normal and saline conditions was evident in alkali grass compared with that in wheat, and electrophysiological analyses indicated that the different uptake probably resulted from the higher K(+)/Na(+) selectivity of the plasma membrane. When external [K(+)] was high, K(+) uptake and transport from roots to shoots were inhibited by exogenous Cs(+), while TEA (tetraethylammonium) only inhibited K(+) transport from the root to the shoot. K(+) uptake was not influenced by Cs(+) when plants were K(+) starved. It was shown by X-ray microanalysis that high [K(+)] and low [Na(+)] existed in the endodermal cells of alkali grass roots, suggesting this to be the tissue where Cs(+) inhibition occurs. These results suggest that the K(+)/Na(+) selectivity of potassium channels and the existence of an apoplastic barrier, the Casparian bands of the endodermis, lead to the lateral gradient of K(+) and Na(+) across root tissue, resulting not only in high levels of [K(+)] in the shoot but also a large [Na(+)] gradient between the root and the shoot.


Assuntos
Poaceae/fisiologia , Potássio/metabolismo , Sódio/metabolismo , Triticum/fisiologia , Transporte Biológico , Cálcio/metabolismo , Endoderma/fisiologia , Cinética , Raízes de Plantas/fisiologia , Brotos de Planta/fisiologia , Especificidade da Espécie
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