RESUMEN
PURPOSE: The loss of intervertebral disc (IVD) cells due to excessive apoptosis induced by inflammatory cytokines is a major cause of IVD degeneration. This study aims to explore the mechanism of interleukin-1ß (IL-1ß)-induced apoptosis of annulus fibrosus cells (AFCs). It's hypothesized that IL-1ß induces apoptosis through the extracellular signal-regulated kinase (ERK) pathway in AFCs. METHODS: The mRNA and protein expression levels of apoptosis-associated genes were analyzed by quantitative real-time PCR and Western blotting. The apoptotic rate was measured by flow cytometry. Three experimental groups were established, including Control, IL-1ß, and IL-1ß+U0126 groups, respectively. RESULTS: Increase in the expression of apoptosis-associated genes including B-cell lymphoma-2 associated X (Bax), caspase-3, and caspase-9, and meanwhile, decrease in the expression of B-cell lymphoma-2 (Bcl-2) gene were found in patients with degenerative IVDs. In in vitro tests, both apoptosis and phosphorylated ERK expression in rat AFCs decreased in the IL-1ß+U0126 group compared with the IL-1ß group. The expression levels of Bax, caspase-3, and caspase-9 in AFCs decreased significantly in the IL-1ß+U0126 group compared with those in the IL-1ß group. The expression level of Bcl-2, on the other hand, significantly increased. CONCLUSIONS: Findings from this study suggest that IL-1ß induces apoptosis in AFCs through the ERK pathway, and therefore, ERK inhibition may provide certain protection against the adverse effects of IL-1ß.
Asunto(s)
Anillo Fibroso/metabolismo , Apoptosis , Interleucina-1beta/metabolismo , Degeneración del Disco Intervertebral/metabolismo , Sistema de Señalización de MAP Quinasas , Adulto , Anciano , Anillo Fibroso/patología , Butadienos/farmacología , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Degeneración del Disco Intervertebral/patología , Masculino , Persona de Mediana Edad , Nitrilos/farmacologíaRESUMEN
We report that vertical graphene coating can greatly improve the electrochemical performance and the interfacial stability of silicon nanocone (SNC) anodes for lithium-ion batteries. The coating patterning technology is innovatively employed for side-by-side demonstration of the exclusive influences of graphene coating on the solid-electrolyte interphase (SEI) formation and the structural stability of the SNC electrode. The silicon nanocone-graphene (SNC-G) electrode achieves a longer cycle life (1715 cycles), higher Coulombic efficiency (average 98.2%), better rate capability, and lower electrode polarization than the SNC electrode. The patterning of the graphene coating provides a much direct and convincing morphological comparison between the SNC-G structure and the SNC structure, showing clearly that the SNC-G area maintains a thin SEI layer and stable nanostructure after cycling, while the SNC area is gradually damaged and covered with a thick SEI layer after 100 cycles. Our results clearly indicate the improved electrochemical performance and interfacial stability attributed to the vertical graphene coating, and the as-proposed patterning technology also paves a new way for comparative research on coating materials for lithium-ion batteries.
RESUMEN
Nanotechnology and carbon coating have been applied to silicon anodes to achieve excellent lithium-ion batteries, but the exclusive influence of carbon coating on solid-electrolyte interphase (SEI) formation is difficult to exhibit distinctly because of the impurity and morphological irregularity of most nanostructured anodes. Here, we design a silicon nanocone-carbon (SNC-C) composite structure as a model anode to demonstrate the significant influences of carbon coating on SEI formation and electrochemical performance, unaffectedly as a result of pure electrode component and distinctly due to regular nanocone morphology. As demonstrated by morphological and elemental analysis, compared to the SNC electrode, the SNC-C electrode maintains a thinner SEI layer (â¼10 nm) and more stable structure during cycling as well as longer cycle life (>725 cycles), higher Coulombic efficiency (>99%), and lower electrode polarization. This well-defined structure clearly shows the interface stability attributed to carbon coating and is promising in fundamental research of the silicon anode.
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Thickness, homogeneity and coverage of the surface passivation layer on Si anodes for Li-ion batteries have decisive influences on their cyclic performance and coulombic efficiency, but related information is difficult to obtain, especially during cycling. In this work, a well-defined silicon nanocone (SNC) on silicon wafer sample has been fabricated as a model electrode in lithium ion batteries to investigate the growth of surface species on the SNC electrode during cycling using ex situ scanning electronic microscopy. It is observed that an extra 5 µm thick layer covers the top of the SNCs after 25 cycles at 0.1 C. This top layer has been proven to be a solid electrolyte interphase (SEI) layer by designing a solid lithium battery. It is noticed that the SEI layer is much thinner at a high rate of 1 C. The cyclic performance of the SNCs at 1 C looks much better than that of the same electrode at 0.1 C in the half cell. Our findings clearly demonstrate that the formation of the thick SEI on the naked nanostructured Si anode during low rate cycling is a serious problem for practical applications. An in depth understanding of this problem may provide valuable guidance in designing Si-based anode materials.
RESUMEN
Rechargeable metallic lithium batteries are the ultimate solution to electrochemical storage due to their high theoretical energy densities. One of the key technological challenges is to control the morphology of metallic lithium electrode during electrochemical dissolution and deposition. Here we have investigated the morphology change of metallic lithium electrode after charging and discharging in nonaqueous batteries by ex situ SEM techniques from a top view. Formation of the hole structure after lithium dissolution and the filling of dendrite-like lithium into the holes has been observed for the first time. In addition, an in situ SEM investigation using an all-solid Li/Li(2)O/super aligned carbon nanotube set-up indicates that lithium ions could diffuse across through the surface oxide layer and grow lithium dendrites after applying an external electric field. The growth of lithium dendrites can be guided by electron flow when the formed lithium dendrite touches the carbon nanotube.