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1.
Eur J Pharmacol ; 880: 173165, 2020 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-32423869

RESUMO

Vascular calcification is a highly regulated process similar to osteogenesis involving phenotypic change of vascular smooth muscle cells (VSMCs). 25-Hydroxycholesterol (25-HC), one of oxysterols synthesized by the enzyme cholesterol 25-hydroxylase, has been shown to promote bovine calcifying vascular cells (CVC) calcification. However, whether and how 25-HC regulates vascular calcification are not completely understood. In this study, in vitro and ex vivo models of vascular calcification were used to determine whether 25-HC regulates vascular calcification. Alizarin red staining and calcium content assay showed that 25-HC treatment promoted calcification of rat and human VSMCs in a dose-dependent manner. Similarly, ex vivo study further confirmed that 25-HC accelerated calcification of rat aortic rings. In addition, western blot analysis showed that 25-HC significantly up-regulated the expression of endoplasmic reticulum stress (ERS) signaling molecules including ATF4 and CHOP in VSMCs and flow cytometry analysis revealed that 25-HC increased apoptosis of VSMCs. Moreover, knockdown of CHOP by siRNA blocked 25-HC-induced mineral deposition in VSMCs. Collectively, this study for the first time demonstrates that 25-HC promotes vascular calcification via ATF4/CHOP signaling using in vitro and ex vivo models, suggesting that ERS is involved in the regulation of 25-HC-induced vascular calcification.

2.
Life Sci ; 256: 117824, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32445758

RESUMO

OBJECTIVES: To investigate the effect of glucagon-like peptide-1 (GLP-1) receptor and glucose dependent insulinotrophic polypeptide (GIP) receptor dual agonist DA-JC4 on alleviating Parkinson's disease (PD) and unveil related cellular mechanisms. METHODS: Rotenone was injected to generate a rat PD model, on which the effect of DA-JC4 on motor functions was evaluated by rotational behavioral assay and open field test. The survival of dopaminergic neurons was analyzed, in addition to assays for mitochondrial stress and quantification of neurotransmitter levels using high performance liquid chromatography (HPLC). In cultured hippocampal neurons, the effect of DA-JC4 on mitochondrial stress and related cellular mechanism was analyzed by Flow cytometry, western blotting and reactive oxygen species (ROS). RESULTS: DA-JC4 significantly improved motor functions in PD rats, and elevated levels of major neurotransmitters. By histological analysis, DA-JC4 protected dopaminergic neurons from rotenone-induced cell death, which was associated with reduced mitochondrial stress. Experiments in cultured rat hippocampal neurons validated the neuroprotective role of DA-JC4 against cell apoptosis and mitochondrial stress induced by rotenone. The protective effect of DA-JC4 was later found to be dependent on AKT/JNK signal pathway, as treatment using AKT inhibitor or JNK activator abolished such effects. CONCLUSION: Our results showed that the dual agonist of GLP-1/GIP receptor could ameliorate motor dysfunctions of PD by protecting dopaminergic neurons which was mediated by relieved mitochondrial stress and apoptosis via AKT/JNK signal pathway.

3.
Ann Clin Lab Sci ; 50(2): 219-227, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32366560

RESUMO

OBJECTIVE: MicroRNAs (miRNAs) are associated with hepatocellular carcinoma (HCC) progression and metastasis. However, it is unclear whether they could act as biomarkers for HCC diagnosis and prognosis. METHODS: In this study, the miR-122 and miR-199a expression levels were determined by quantitative real-time PCR (qRT-PCR). The function and molecular mechanism of miR-122 and miR-199a target genes were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Correlation between miRNA expression levels and the overall survival (OS) of HCC patients was assessed by Kaplan-Meier analysis. RESULTS: Serum miR-122 expression had no significant difference between patients with HCC (HCC patients) and healthy controls (HCs), whereas serum miR-199a expression was significantly lower in HCC patients than the HCs (p<0.05). Receiver-operator characteristic (ROC) curve analysis revealed that miR-199a could be an effective diagnostic biomarker for HCC, which was confirmed by obvious expression polarization patterns of miR-199a target genes. Kaplan-Meier analysis revealed that miR-122 expression level was associated with the OS of HCC patients (p<0.001), suggesting that miR-122 could be a prognostic biomarker for HCC. CONCLUSIONS: Collectively, our results showed that circulating miR-199a and miR-122 levels could serve as novel, non-invasive biomarkers for HCC diagnosis and prognosis, respectively.

4.
Neurotox Res ; 38(1): 124-132, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32200526

RESUMO

Obstructive sleep apnea syndrome (OSAS) is known as a repeated obstruction of the upper airway during sleep, leading to generalized hypoxia episodes and associated with cardiovascular and cerebrovascular diseases. We mainly explored the role of neuregulin receptor degradation protein-1 (Nrdp1, also known as FLRF) in brain injury induced by chronic intermittent hypoxia (CIH) in rats. Wistar rats were randomly divided into 4 groups (n = 12 per group), including the sham + adeno-associated virus-NC (AAV-NC) group, the sham + AAV-siNrdp1 group, the IH-4w (intermittent hypoxia for 4 weeks) + AAV-NC group, and the IH-4w + AAV-siNrdp1 group. Morphologic changes in brain tissue were observed by hematoxylin and eosin (HE) staining. Apoptosis in the hippocampus was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Spatial learning and memory were assessed by the Morris water maze test. The expression of Nrdp1 mRNA and protein in the hippocampus was detected by qualitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The concentration of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in serum was detected via enzyme-linked immunosorbent assay (ELISA) kits. Nrdp1 expression was increased after intermittent hypoxia exposure over time. Western blotting and H&E results showed that pathological changes of hippocampus neurons in chronic intermittent hypoxia rat were diminished by shNrdp1. Western blotting and TUNEL staining showed that apoptotic cells in the hippocampus of CIH rats were decreased by shNrdp1. The Morris water maze results proved that shNrdp1 improved spatial learning performance of chronic intermittent hypoxia rats. ELISA kits results showed that CIH-induced inflammatory response was decreased by shNrdp1. Western blotting and qRT-PCR results showed protein expression of ErbB3 in the hippocampus of CIH rats. Nrdp1 could regulate ErbB3 protein levels in brain-injured rats with CIH, which demonstrates that Nrdp1 is a potential therapeutic target in the cognition deficits associated with OSAS.

5.
J Colloid Interface Sci ; 567: 339-346, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32065908

RESUMO

An industrial electro-catalyst obliges three essential features, such as scalability, generating high current density at low overpotential, and long-term stability. Herein, we tackle those challenges using NiSx-MoO2 nanosponges on carbon cloth based hydrogen evolution catalyst. The target catalyst was synthesized through a series of simple and scalable methods, including dissolution, reconstruction, and chemical vapor deposition. The optimized NiSx-MoO2/CC catalyst exhibits a superior hydrogen evolution catalytic activity far better than commercial Pt/C meanwhile surpasses widely used industrial Raney Ni catalyst by many aspects, namely lower overpotential at 500 mA cm-2 current density and smaller Tafel plot in 30 wt% KOH solution. This excellent electrocatalytic activity is attributed to enhanced mass transfer and faster reaction kinetics due to the unique hierarchical porous structures, as well as the synergistic electron transfer effect between the two components of NiSx and MoO2 species. This work may provide a new strategy for the design of better hydrogen evolution catalyst for industrial application.

6.
J Colloid Interface Sci ; 564: 276-285, 2020 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-31918195

RESUMO

Rational design of a stable, highly active non-precious metal-based electrocatalysts for oxygen reduction reaction (ORR) is vitally important for industrial application of fuel cells technology. As a potential alternative of Pt/C catalyst, two-dimensional (2D) porous carbon materials are widely investigated due to the highly accessible surface area and active sites, wherein carbon films doped with a plurality of metals and non-metal elements are rarely reported due to an uncontrollable synthesis process. Here, a bi-metallic (NiCo alloy nanoparticles) and nonmetallic (N) co-doped porous carbon film (Ni-Co-N@CF) is fabricated by a simple controllable and scalable strategy comprising the synthesis of NiCo alloy nanoparticles, modification of organic molecules, and high-temperature carbonization process. The optimized Ni-Co-N@CF catalyst shows an excellent ORR electrocatalytic activity with a larger electrochemically active surface area (2.31 m2 g-1), a higher half-wave potential (0.86 V) and a lower diffusion limited current density (-4.43 mA cm-2) than all the prepared control catalysts. Moreover, the designated catalyst also exhibits high durability and superior methanol tolerance in alkaline media, significantly better than the commercial Pt/C (20 wt%). The superior ORR performance is attributed to the synergetic interactions of ternary doping of Ni/Co/N in the 2D film skeleton, which not only greatly enhances conductivity but also provides more Co-N active sites.

7.
Aging (Albany NY) ; 12(1): 672-689, 2020 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-31927536

RESUMO

BACKGROUND: This study is conducted to investigate the protective role of elevated microRNA-375 (miR-375) in dopaminergic neurons in Parkinson's disease through down-regulating transcription factor specificity protein 1 (SP1). RESULTS: The successfully modeled rats with Parkinson's disease showed aggregated neurobehavioral change, increased neuroinflammatory response and oxidative stress, and lowered dopamine content. Parkinson's disease rats treated with overexpressed miR-375 displayed improved neurobehavioral change, ameliorated neuroinflammatory response and oxidative stress, heightened dopamine content and abated neuronal apoptosis by down-regulating SP1. Up-regulation of SP1 reversed the protective effect of upregulated miR-375 on Parkinson's disease. CONCLUSION: Up-regulation of miR-375 ameliorated the damage of dopaminergic neurons, reduced oxidative stress and inflammation in Parkinson's disease by inhibiting SP1. METHODS: Parkinson's disease rat model was established by targeted injection of 6-hydroxydopamine to damage the substantia nigra striatum. The successfully modeled Parkinson's disease rats were intracerebroventricularly injected with miR-375 mimics or pcDNA3.1-SP1. The functions of miR-375 and SP1 in neurobehavioral change, neuroinflammatory response, oxidative stress, dopamine content and expression of apoptosis-related proteins in the substantia nigra of Parkinson's disease rats were evaluated. The target relation of miR-375 and SP1 was confirmed by bioinformatics analysis and dual luciferase reporter gene assay.

8.
Adv Sci (Weinh) ; 6(23): 1900767, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31832307

RESUMO

So far, thymus involution in adults is believed to be irreversible, and endogenous innovation for thymus-related immunodeficiency remains to be an intractable puzzle. With the expectation of addressing this dilemma, human ovarian surface epithelium (OSE) has been reengineered as epithelial-mesenchymal transition (EMT)-tridimensional-spheroid biologics (ETSB) using a dynamic EMT-3D-floating system along with 160 Gy X-ray-amelioration, which inoculates subcutaneously into aging rhesus and athymic Balb/c nu/nu mice. Herein, it is bioinformatically validated that ETSB can reset Clock/Arntl-Per3/Tim molecule rhythm dynamics to re-prime thymus residual (parathyroid or fatty-like invalid vesicles yet no thymic architecture) to evolutionary transcription with overall cortex-medulla endogenized by TECs undergoing MET/EMT reversion. Rhythm dynamics immediately resettles the bHLH-LTßR-NFκB-RelA/B loop as a cascade to provoke the core immune microenvironment for multifunctional innovation of dynamic TCR orchestration, with harmonious naïve T-subsets and TRECs renewals (P < 0.005). Subsequently, peripheral biological burden and tumor metastasis dynamics are addressed by innovative TCR-defense/attack dynamics quickly (P < 0.005 vs Control), yet without autoimmune indication to hosts. Moreover, a functional blockade of core-rhythm dynamics deeply impedes the endogenous innovation of invalid thymus residual. Thus this study may help pioneer a prospective strategy to innovate panoramic central-peripheral immune microenvironments and defense dynamics for immune-deficient/aging victims.

10.
J Comput Biol ; 26(12): 1448-1457, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31356108

RESUMO

Angiitis, also known as vasculitis, is a chronic inflammatory disease characterized by the infiltration of inflammatory cells in surroundings of blood vessels, accompanied by vascular damage including fibrin deposition, collagen fiber degeneration, myocyte, and endotheliocyte necrosis. This work aimed to perform an integrated bioinformatic analysis of three data sets concerning vasculitis to explore and examine the potential diagnostic and therapeutic makers contributing to illuminating the pathomechanisms of vasculitis. We collected three sets of gene expression data designed by dual-channel method from Gene Expression Omnibus, which were based on the same platform (Agilent-014850 Whole Human Genome Microarray 4x44K G4112F). The meta-analysis was used to analyze the gene expression profiles and screen the differentially expressed genes followed by functional features identification. Subsequently, a protein-protein interaction and transcriptional regulation network were conducted for further investigation of expression mechanisms of vasculitis. Totally, 73 consistently upregulated genes, 49 consistently downregulated genes, and 26 genes with different expression directions were identified. Functional enrichment and transcription regulation analysis suggested upregulated genes (PPBP, PLAU, and HIST1H2BH) and downregulated genes such as IL23A gene were predominately associated with immune responses and cytokine receptors function. In addition, specific cancer-related genes such as MRVI1 was also extracted and considered as promising biomarkers of the development and progression of vasculitis. This study established an integrated meta-analysis approach and identified novel biomarkers involved in vasculitis, which further facilitate to explore and unravel the etiopathogenesis of vasculitis.

11.
Int Immunopharmacol ; 75: 105734, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31301558

RESUMO

This study is conducted to investigate the role of lncRNA urothelial carcinoma-associated 1 (UCA1) in the protection of dopaminergic neurons in Parkinson's disease (PD) through regulating the PI3K/Akt signaling pathway. PD rat model was induced by injection of 6-hydroxydopamine (6-OHDA) to damage the substantia nigra striatum. The successfully modeled PD rats were introduced with siRNA-negative control (NC) or UCA1-siRNA. The expression of UCA1 in neurobehavioral change, neuroinflammatory response and oxidative stress of PD rats were explored. The effect of UCA1 on the PI3K/Akt signaling pathway and downstream proteins IκBα and ERK was also investigated. The rats with PD exhibited aggregated neurobehavioral change, increased neuroinflammatory response and oxidative stress. Down-regulation of UCA1 up-regulated the expression of TH positive cells and DA content, reduced the apoptosis of substantia nigra neurons, the apoptosis of substantia nigra neurons and oxidative stress and improved the neuroinflammatory response in PD rats. Down-regulation of UCA1 inhibited the activation of the PI3K/AKT signaling pathway in substantia nigra of PD rats. Our study suggests that the downregulated lncRNA UCA1 ameliorates the damage of dopaminergic neurons, reduces oxidative stress and inflammation in PD rats through the inhibition of the PI3K/Akt signaling pathway.


Assuntos
Transtornos Parkinsonianos/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Longo não Codificante/genética , Animais , Neurônios Dopaminérgicos/patologia , Regulação para Baixo , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Masculino , Estresse Oxidativo , Transtornos Parkinsonianos/genética , Transtornos Parkinsonianos/patologia , RNA Interferente Pequeno/genética , Ratos Wistar , Transdução de Sinais , Substância Negra/metabolismo
12.
ACS Appl Mater Interfaces ; 11(23): 20752-20761, 2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31091878

RESUMO

The facile synthesis of hierarchically functional, catalytically active, and electrochemically stable nanostructures holds a tremendous promise for catalyzing the efficient and durable oxygen evolution reaction (OER) and yet remains a formidable challenge. Herein, we report the scalable production of core-shell nanostructures composed of carbon-coated cobalt diphosphide nanosheets, C@CoP2, via three simple steps: (i) electrochemical deposition of Co species, (ii) gas-phase phosphidation, and (iii) carbonization of CoP2 for catalytic durability enhancement. Electrochemical characterizations showed that C@CoP2 delivers an overpotential of 234 mV, retains its initial activity for over 80 h of continuous operation, and exhibits a fast OER rate of 63.8 mV dec-1 in base.

13.
Neurocrit Care ; 30(1): 81-87, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-29995185

RESUMO

BACKGROUND: Prognostic significance of serum calcium level in patients with intracerebral hemorrhage is not well studied. The aim of the study was to identify if a relationship between admission serum calcium level and prognosis exists in patients with intracerebral hemorrhage. METHODS: A total of 1262 confirmed intracerebral hemorrhage patients were included. Demographic data, medical history, medicine history, laboratory data, imaging data, clinical score, and progress note were collected from their medical records. All images of head computed tomography were reanalyzed. Ninety-day prognosis was recorded, and poor outcome was defined as death or major disability caused by intracerebral hemorrhage. RESULTS: During the 90-day follow-up period, 504 patients died and 226 patients suffered from major disability. Death and major disability were combined as poor prognosis. The remaining 532 patients showed good prognosis. Admission serum calcium level was lower in the patients with poor prognosis than in the patients with good prognosis (2.41 ± 0.23 mmol/l, 2.55 ± 0.26 mmol/l, P < 0.001). Admission INR and hematoma volume were higher in the patients with poor prognosis than in the patients with good prognosis (INR: 1.74 ± 0.29, 1.70 ± 0.29, P = 0.029; hematoma volume: 11.6 ± 4.4 ml, 10.7 ± 4.1 ml, P < 0.001). There was no difference in admission APTT level between the two prognosis groups (28.4 ± 5.6 s, 27.8 ± 5.4 s, P = 0.056). A multivariate COX regression analysis reported that admission serum calcium level ≤ 2.41 mmol/l was associated with the increased risk of poor prognosis (death or major disability) in the patients (HR 1.45, 95% CI 1.32-1.60). In addition, there was a significant linear association of serum calcium level with coagulation function markers and hematoma volume on admission (APTT: r = - 0.091, P = 0.001; INR: r = - 0.063, P = 0.025; hematoma volume: r = -0.108, P < 0.001). CONCLUSIONS: Admission serum calcium level might be a prognostic marker for intracerebral hemorrhage. Potential mechanism involved calcium-induced coagulation function abnormality.


Assuntos
Cálcio/sangue , Hemorragia Cerebral/sangue , Hemorragia Cerebral/diagnóstico , Avaliação de Resultados em Cuidados de Saúde , Idoso , Biomarcadores/sangue , Hemorragia Cerebral/mortalidade , Hemorragia Cerebral/terapia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Admissão do Paciente , Prognóstico
14.
Chem Commun (Camb) ; 54(80): 11324-11327, 2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-30238949

RESUMO

A simple and efficient catalyst, benzimidazole (BIMH)-modified copper foil, is developed to enhance the selective conversion of CO2 to C2/C3 products. The overall faradaic efficiency (FE) for CO2 reduction reaches 92.1% and the undesired hydrogen evolution reaction (HER) is lowered to a FE of 7% at -1.07 VRHE.

15.
Neurol Res ; 40(8): 702-708, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29688151

RESUMO

Objectives Early brain injury (EBI) is considered to be one of the main causes of poor outcome in subarachnoid hemorrhage (SAH) patients. Bexarotene is an agonist of retinoid X receptor and plays a protective role in central nervous system diseases. However, the exact role of bexarotene in SAH has not been reported. Therefore, the present study was to determine whether bexarotene administration attenuate EBI after SAH in mice and to explore the underlying mechanism. Methods SAH was induced in C57BL/6 mice by endovascular perforation. Bexarotene was administrated intraperitoneally. Neurological score, cell death, microglia activation, and pro-inflammatory cytokines were detected at 24 h after SAH. The expression of PPARγ was measured by Western blot. Results Results showed that bexarotene significantly improved neurological score after SAH. In addition, the number of cell death and activated microglia were significantly reduced by bexarotene administration. Compared with vehicle-treated mice, bexarotene-treated mice showed reduced pro-inflammatory cytokines after SAH. The expression of PPARγ was significantly increased with bexarotene treatment compared with vehicle-treated controls. Discussion The present study demonstrats that bexarotene administration protects against EBI after SAH, inhibiting cell death, attenuating microglia activation, and alleviating neuroinflammation. The underlying mechanism may partially involve the activation of PPARγ.


Assuntos
Encéfalo/efeitos dos fármacos , Microglia/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , PPAR gama/metabolismo , Hemorragia Subaracnóidea/tratamento farmacológico , Tetra-Hidronaftalenos/farmacologia , Animais , Bexaroteno , Encéfalo/metabolismo , Encéfalo/patologia , Morte Celular/efeitos dos fármacos , Citocinas/metabolismo , Modelos Animais de Doenças , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Inflamação/patologia , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Microglia/patologia , RNA Mensageiro/metabolismo , Hemorragia Subaracnóidea/metabolismo , Hemorragia Subaracnóidea/patologia
16.
Nanoscale ; 10(7): 3444-3450, 2018 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-29393949

RESUMO

Recent experimental and theoretical studies have demonstrated that two-dimensional (2D) transition metal dichalcogenide (TMDC) nanoflakes are one of the most promising candidates for non-noblemetal electrocatalysts for hydrogen evolution reaction (HER). However, it is still challenging to optimize their conductivity and enrich active sites for highly efficient electrochemical performance. Herein, we report a chemical vapor deposition (CVD) and thermal annealing two-step strategy to controllably synthesize hybrid electrocatalysts consisting of metallic NbS2 nanoflake backbones and a highly catalytic active MoSx nanocrystalline shell on polished commercial glass carbon (GC). In addition, the amount of MoSx in the hybrids can be easily adjusted. We first demonstrate that a small amount of MoSx significantly promotes the HER activity of 2D NbS2 nanoflakes, which is in good agreement with the density functional theory (DFT) calculation results. Moreover, the optimized MoSx@NbS2/GC electrocatalyst displays superior HER activity with overpotential of -164 mV at -10 mA cm-2, a small Tafel slope of 43.2 mV dec-1, and prominent electrochemical stability. This study provides a new path for enhancing the HER performance of 2D TMDC nanoflakes.

17.
Adv Mater ; 29(44)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29024072

RESUMO

The emerging molybdenum disulfide (MoS2 ) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2 ) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.

18.
ACS Appl Mater Interfaces ; 9(9): 8047-8054, 2017 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-28221020

RESUMO

Reconstructing carbon nanomaterials (e.g., fullerene, carbon nanotubes (CNTs), and graphene) to multidimensional networks with hierarchical structure is a critical step in exploring their applications. Herein, a sacrificial template method by casting strategy is developed to prepare highly flexible and free-standing carbon film consisting of CNTs, graphene, or both. The scalable size, ultralight and binder-free characteristics, as well as the tunable process/property are promising for their large-scale applications, such as utilizing as interlayers in lithium-sulfur battery. The capability of holding polysulfides (i.e., suppressing the sulfur diffusion) for the networks made from CNTs, graphene, or their mixture is pronounced, among which CNTs are the best. The diffusion process of polysulfides can be visualized in a specially designed glass tube battery. X-ray photoelectron spectroscopy analysis of discharged electrodes was performed to characterize the species in electrodes. A detailed analysis of lithium diffusion constant, electrochemical impedance, and elementary distribution of sulfur in electrodes has been performed to further illustrate the differences of different carbon interlayers for Li-S batteries. The proposed simple and enlargeable production of carbon-based networks may facilitate their applications in battery industry even as a flexible cathode directly. The versatile and reconstructive strategy is extendable to prepare other flexible films and/or membranes for wider applications.

19.
ACS Appl Mater Interfaces ; 8(49): 33673-33680, 2016 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-27960387

RESUMO

A well-dispersed PtCu alloy nanoparticles (NPs) on three-dimensional nitrogen-doped graphene (PtCu/3D N-G) electrocatalyst has been successfully synthesized by a conventional hydrothermal method combined with a high-efficiency microwave-assisted polyol process. The morphology, composition, and structures are well-characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. Cyclic voltammograms illustrate that the as-prepared PtCu/3D N-G electrocatalyst possesses the larger electrochemical active surface area, lower onset potential, higher current density, and better tolerance to CO poisoning than PtCu NPs on reduced graphene oxide and XC-72 carbon black in acid solution. In addition, long-time chronoamperometry reveals that the PtCu/3D N-G catalyst exhibits excellent stability even longer than 60 min toward acid methanol electrooxidation. The remarkably enhanced performance is related to the combined effects of uniformly interconnected three-dimensional porous graphene networks, nitrogen doping, modified Pt alloy NPs, and strong binding force between Pt alloy NPs and 3D N-G structures.

20.
Small ; 12(40): 5530-5537, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27578319

RESUMO

The remote hydrogen plasma is able to create abundant S-vacancies on amorphous molybdenum sulfide (a-MoSx ) as active sites for hydrogen evolution. The results demonstrate that the plasma-treated a-MoSx exhibits superior performance and higher stability than Pt in a proton exchange membrane based electrolyzers measurement as a proof-of-concept of industrial application.

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