Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Microbiol Biotechnol ; 34(3): 689-699, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38346819

RESUMO

Colitis is a major gastrointestinal disease that threatens human health. In this study, a synbiotic composed of inulin and Pediococcus acidilactici (P. acidilactici) was investigated for its ability to alleviate dextran sulfate sodium (DSS)-induced colitis. The results revealed that the synbiotic, composed of inulin and P. acidilactici, attenuated the body weight loss and disease activity index (DAI) score in mice with DSS-mediated colitis. Determination of biochemical indicators found that the synbiotic increased anti-oxidation and alleviated inflammation in mice. Additionally, histopathological examination revealed that colonic goblet cell loss and severe mucosal damage in the model group were significantly reversed by the combination of inulin and P. acidilactici. Moreover, synbiotic treatment significantly reduced the levels of IL-1ß, TNF-α, and IL-6 in the serum of mice. Thus, a synbiotic composed of inulin and P. acidilactici has preventive and therapeutic effects on DSSinduced colitis in mice.


Assuntos
Colite Ulcerativa , Colite , Pediococcus acidilactici , Simbióticos , Humanos , Animais , Camundongos , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/tratamento farmacológico , Colite Ulcerativa/patologia , Inulina/farmacologia , Sulfato de Dextrana/toxicidade , Colite/induzido quimicamente , Colo/patologia , Camundongos Endogâmicos C57BL , Modelos Animais de Doenças
2.
Chemistry ; 28(63): e202202700, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36117272

RESUMO

The artificially accurate design of nonmetal electrocatalysts' active site has been a huge challenge because no pure active species with the specific structure could be strictly controlled by traditional synthetic methods. Species with a multiconfiguration in the catalyst hinder identification of the active site and the subsequent comprehension of the reaction mechanism. We have developed a novel electro-assisted molecular assembly strategy to obtain a pure pentagon ring on perfect graphene avoiding other reconstructed structures. More importantly, the active atom was confirmed by the subtle passivation process as the topmost carbon atom. Recognition of the carbon-defect electrocatalysis reaction mechanism was first downsized to the single-atom scale from the experimental perspective. It is expected that this innovative electro-assisted molecular assembly strategy could be extensively applied in the active structure-controlled synthesis of nonmetal electrocatalysts and verification of the exact active atom.

3.
Adv Mater ; 34(26): e2201422, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35429018

RESUMO

Cancers heavily threaten human life; therefore, a high-accuracy diagnosis is vital to protect human beings from the suffering of cancers. While biopsies and imaging methods are widely used as current technologies for cancer diagnosis, a new detection platform by metabolic analysis is expected due to the significant advantages of fast, simple, and cost-effectiveness with high body tolerance. However, the signal of molecule biomarkers is too weak to acquire high-accuracy diagnosis. Herein, precisely engineered metal-organic frameworks for laser desorption/ionization mass spectrometry, allowing favorable charge transfer within the molecule-substrate interface and mitigated thermal dissipation by adjusting the phonon scattering with metal nodes, are developed. Consequently, a surprising signal enhancement of ≈10 000-fold is achieved, resulting in diagnosis of three major cancers (liver/lung/kidney cancer) with area-under-the-curve of 0.908-0.964 and accuracy of 83.2%-90.6%, which promises a universal detection tool for large-scale clinical diagnosis of human cancers.


Assuntos
Estruturas Metalorgânicas , Neoplasias , Humanos , Estruturas Metalorgânicas/química , Metais/química , Neoplasias/diagnóstico , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
4.
Molecules ; 27(5)2022 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-35268811

RESUMO

Reducing the surface reflectivity of silicon substrates is essential for preparing high-performance Si-based solar cells. We synthesized pyramid-nanowire-structured Si (Si-PNWs) anti-reflection substrates, which have excellent light-trapping ability (<4% reflectance). Furthermore, diethyl phthalate (DEP), a water-insoluble phthalic acid ester, was applied to optimize the Si-PNWs/PEDOT:PSS interface; the photoelectric conversion efficiency of heterojunction solar cells was shown to increase from 9.82% to 13.48%. We performed a detailed examination of the shape and optical characteristics of Si-PNWs, as well as associated photoelectric performance tests, to investigate the origin of performance improvements in Si-PNWs/PEDOT:PSS heterojunction solar cells (HSCs).

5.
J Am Chem Soc ; 144(5): 2171-2178, 2022 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-34995077

RESUMO

The coordinated configuration of atomic platinum (Pt) has always been identified as an active site with high intrinsic activity for hydrogen evolution reaction (HER). Herein, we purposely synthesize single vacancies in a carbon matrix (defective graphene) that can trap atomic Pt to form the Pt-C3 configuration, which gives exceptionally high reactivity for HER in both acidic and alkaline solutions. The intrinsic activity of Pt-C3 site is valued with a turnover frequency (TOF) of 26.41 s-1 and mass activity of 26.05 A g-1 at 100 mV, respectively, which are both nearly 18 times higher than those of commercial 20 wt % Pt/C. It is revealed that the optimal coordination Pt-C3 has a stronger electron-capture ability and lower Gibbs free energy difference (ΔG), resulting in promoting the reduction of adsorbed H+ and the acceleration of H2 desorption, thus exhibiting the extraordinary HER activity. This work provides a new insight on the unique coordinated configuration of dispersive atomic Pt in defective C matrix for superior HER performance.

6.
Life Sci ; 276: 119412, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33774025

RESUMO

AIMS: The effects of PFKFB4 on glycolysis during the cancer progression has been investigated, while its role in glioma remains unclear. The present study evaluated the molecular mechanism of PFKFB4 in glycolysis of glioma progression. MATERIALS AND METHODS: The pan-cancer platform SangerBox was inquired to investigate the E2F2 expression in tumors. The E2F2 expression was studied by qRT-PCR and immunohistochemistry in collected glioma and normal brain tissues and by qRT-PCR and western blot in glioma cells. The relationship between the E2F2 expression in glioma tissues and patients' prognosis was analyzed. The cell malignant phenotype, glycolysis, growth and metastasis were examined by CCK-8, EdU, colony formation, flow cytometry, wound healing, Transwell assays, ELISA kits, and tumorigenesis and metastasis assays. Downstream targets of E2F2 were searched in hTFtarget, followed by pathway enrichment analysis. The expression of these targets and their correlation with E2F2 expression in gliomas were investigated through the GEPIA website. After ChIP and luciferase assays, the effect of the target on glioma was investigated. KEY FINDINGS: E2F2 was overexpressed in glioma patients and predicted poor prognoses. E2F2 promoted cell proliferation, colony formation, DNA synthesis, migration, invasion and glycolysis, and inhibited apoptosis. Meanwhile, inhibition of E2F2 suppressed the growth and metastasis of gliomas. E2F2 elevated the PFKFB4 expression transcriptionally by binding to its promoter and activated PI3K/AKT pathway. The promotion of glioma metastasis and glycolysis by E2F2 was mitigated by PFKFB4 knockdown. SIGNIFICANCE: E2F2-mediated transcriptional enhancement of PFKFB4 expression regulated the phosphorylation of PI3K/AKT to promote glioma malignancy progression.


Assuntos
Biomarcadores Tumorais/metabolismo , Fator de Transcrição E2F2/metabolismo , Regulação Neoplásica da Expressão Gênica , Glioma/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Fosfofrutoquinase-2/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Apoptose , Biomarcadores Tumorais/genética , Proliferação de Células , Fator de Transcrição E2F2/genética , Feminino , Glioma/genética , Glioma/metabolismo , Glicólise , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Pessoa de Meia-Idade , Fosfatidilinositol 3-Quinases/genética , Fosfofrutoquinase-2/genética , Fosforilação , Prognóstico , Proteínas Proto-Oncogênicas c-akt/genética , Taxa de Sobrevida , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
7.
IUBMB Life ; 73(5): 784-799, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33715270

RESUMO

The epigenetic abnormality is believed as a major driver for cancer initiation. Histone modification plays a vital role in tumor formation and progression. Particularly, alteration in histone acetylation has been highly associated with gene expression, cell cycle, as well as carcinogenesis. By analyzing glioblastoma (GBM)-related microarray from the GEO database and conducting chromatin immunoprecipitation-sequencing (ChIP-seq), we discovered that solute carrier family 30 member 3 (SLC30A3), a super enhancer (SE)-regulated factor, was significantly reduced in GBM tissues. Furthermore, histone deacetylase 1 (HDAC1), overexpressed in GBM tissues, could inhibit SLC30A3 expression by promoting histone H3K27ac deacetylation modification of the SE region of SLC30A3. Our functional validation revealed that SLC30A3 can inhibit the growth and metastatic spread of GBM cells in vitro and in vivo, and can activate the MAPK signaling pathway to promote apoptosis of GBM cells. Moreover, overexpression of HDAC1 resulted in a significant increase in DNA replication activity, a significant decline in apoptosis and cell cycle arrest in GBM cells. In a word, these findings indicate that combined epigenetic targeting of SLC30A3 by HDAC1 and SE is potentially therapeutically feasible in GBM.


Assuntos
Neoplasias Encefálicas/patologia , Proteínas de Transporte de Cátions/genética , Glioblastoma/patologia , Código das Histonas , Histona Desacetilase 1/fisiologia , Proteínas de Neoplasias/fisiologia , Acetilação , Adulto , Idoso , Animais , Apoptose , Neoplasias Encefálicas/genética , Pontos de Checagem do Ciclo Celular , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , DNA de Neoplasias/genética , Transição Epitelial-Mesenquimal , Feminino , Glioblastoma/genética , Xenoenxertos , Sequenciamento de Nucleotídeos em Larga Escala , Histona Desacetilase 1/genética , Humanos , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Pessoa de Meia-Idade , Metástase Neoplásica , Proteínas de Neoplasias/genética , Fenótipo , Processamento de Proteína Pós-Traducional , Adulto Jovem
8.
Angew Chem Int Ed Engl ; 59(34): 14664-14670, 2020 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-32495475

RESUMO

The oxygen vacancies of defective iron-cobalt oxide (FeCoOx -Vo) nanosheets are modified by the homogeneously distributed sulfur (S) atoms. S atoms can not only effectively stabilize oxygen vacancies (Vo), but also form the Co-S coordination with Co active site in the Vo, which can modulate the electronic structure of the active site, enabling FeCoOx -Vo-S to exhibit much superior OER activity. FeCoOx -Vo-S exhibits a mass activity of 2440.0 A g-1 at 1.5 V vs. RHE in 1.0 m KOH, 25.4 times higher than that of RuO2 . The Tafel slope is as low as 21.0 mV dec-1 , indicative of its excellent charge transfer rate. When FeCoOx -Vo-S (anode catalyst) is paired with the defective CoP3 /Ni2 P (cathode catalyst) for overall water splitting, current densities of as high as 249.0 mA cm-2 and 406.0 mA cm-2 at a cell voltage of 2.0 V and 2.3 V, respectively, can be achieved.

9.
Angew Chem Int Ed Engl ; 58(38): 13565-13572, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31328904

RESUMO

Metal-organic framework (MOFs) two-dimensional (2D) nanosheets have many coordinatively unsaturated metal sites that act as active centres for catalysis. To date, limited numbers of 2D MOFs nanosheets can be obtained through top-down or bottom-up synthesis strategies. Herein, we report a 2D oxide sacrifice approach (2dOSA) to facilely synthesize ultrathin MOF-74 and BTC MOF nanosheets with a flexible combination of metal sites, which cannot be obtained through the delamination of their bulk counterparts (top-down) or the conventional solvothermal method (bottom-up). The ultrathin iron-cobalt MOF-74 nanosheets prepared are only 2.6 nm thick. The sample enriched with surface coordinatively unsaturated metal sites, exhibits a significantly higher oxygen evolution reaction reactivity than bulk FeCo MOF-74 particles and the state-of-the-art MOF catalyst. It is believed that this 2dOSA could provide a new and simple way to synthesize various ultrathin MOF nanosheets for wide applications.

10.
Angew Chem Int Ed Engl ; 58(28): 9404-9408, 2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31106512

RESUMO

Atomic metal species-based catalysts (AMCs) show remarkable possibilities in various catalytic reactions. The coordination configuration of the metal atoms has been widely recognized as the determining factor to the electronic structure and the catalytic activity. However, the synergistic effect between the adjacent layers of the multilayered AMCs is always neglected. We reported an atomic Co and Pt co-trapped carbon catalyst, which exhibits a ultrahigh activity for HER in the wide range of pH (η10 =27 and 50 mV in acidic and alkaline media, respectively) with ultralow metal loadings (1.72 and 0.16 wt % for Co and Pt, respectively), which is much superior to the commercial Pt/C. Theoretical analysis reveals that the atomic metals on the inner graphitic layers significantly alter the electronic structure of the outmost layer, thus tailoring the HER activity. This finding arouses a re-thinking of the intrinsic activity origins of AMCs and suggests a new avenue in the structure design of AMCs.

11.
J Cell Physiol ; 234(7): 10671-10679, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30480816

RESUMO

Aberrant expressions of long noncoding RNAs (lncRNAs) contribute to carcinogenesis via regulating tumor suppressors or oncogenes. LncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) has been recognized as an oncogene to promote tumor progression of many cancers. However, the function of NEAT1 in glioma remains poorly discovered. Currently, we focused on the role of NEAT1 in glioma. Here, we found that NEAT1 was greatly upregulated in glioma cells compared with normal human astrocytes (NHAs). Meanwhile, miR-107 was significantly downregulated in glioma cell lines. Then, we observed that knockdown of NEAT1 suppressed the growth and invasion of glioma cells including U251 and SW1783 cells. Reversely, overexpression of NEAT1 dramatically induced glioma cell survival, increased cell colony formation, and promoted cell invasion ability. Subsequently, bioinformatics analysis was performed to predict the correlation between NEAT1 and miR-107. Moreover, it was revealed that NEAT1 could modulate miR-107 via serving as an endogenous sponge of miR-107. The direct binding correlation between NEAT1 and miR-107 was validated in our study. In addition, cyclin dependent kinase 14 (CDK14) was predicted as an messenger RNA target of miR-107 and the association between them was confirmed in our research. Moreover, we implied that NEAT1 demonstrated its biological functions via regulating miR-107 and CDK14 in vivo. In summary, our findings indicated that NEAT1/miR-107/CDK14 axis participated in glioma development. NEAT1 could act as a significant prognostic biomarker in glioma progression.


Assuntos
Quinases Ciclina-Dependentes/genética , Glioma/genética , MicroRNAs/genética , RNA Longo não Codificante/genética , Apoptose/genética , Astrócitos/metabolismo , Astrócitos/patologia , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica/genética , Técnicas de Silenciamento de Genes , Glioma/patologia , Humanos , Invasividade Neoplásica/genética , Ligação Proteica
12.
Adv Mater ; 31(4): e1805581, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30488551

RESUMO

Rational design and synthesis of hetero-coordinated moieties at the atomic scale can significantly raise the performance of the catalyst and obtain mechanistic insight into the oxygen-involving electrocatalysis. Here, a facile plasma-photochemical strategy is applied to construct atomically coordinated Pt-Co-Se moieties in defective CoSe2 (CoSe2- x ) through filling the plasma-created Se vacancies in CoSe2- x with single Pt atomic species (CoSe2- x -Pt) under ultraviolet irradiation. The filling of single Pt can remarkably enhance the oxygen evolution reaction (OER) activity of CoSe2 . Optimal OER specific activity is achieved with a Pt content of 2.25 wt% in CoSe2- x -Pt, exceeding that of CoSe2- x by a factor of 9. CoSe2- x -Pt shows much better OER performance than CoSe2- x filled with single Ni and even Ru atomic species (CoSe2- x -Ni and CoSe2- x -Ru). Noticeably, it is general that Pt is not a good OER catalyst but Ru is; thus the design of active sites for electrocatalysis at an atomic level should follow a different intrinsic mechanism. Mechanism studies unravel that the single Pt can induce much higher electronic distribution asymmetry degree than both single Ni and Ru, and benefit the interaction between the Co sites and adsorbates (OH*, O*, and OOH*) during the OER process, leading to a better OER activity.

13.
Angew Chem Int Ed Engl ; 57(50): 16421-16425, 2018 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-30332523

RESUMO

Various strategies, such as increasing active site numbers and structural and surface engineering, have been used to improve the oxygen evolution reaction (OER) performance of transition-metal dichalcogenides. However, it is challenging to combine these strategies in one system to realize the full catalytic potential. Now, an Ar/O2 plasma method is used to simultaneously induce exfoliation, surface reorganization (formation of an oxidative layer with rich oxygen vacancies), and phase transformation (cubic-to-orthorhombic) on CoSe2 to generate an exceptionally outstanding OER electrocatalysts. The as-made samples require an overpotential of only 251 mV at 10 mA cm-2 , outperforming commercial RuO2 and most reported OER catalysts. The striking catalytic activity originates from the optimized chemical and electronic environment. This work provides valuable insights into the design of promising OER electrocatalysts with high natural abundance via multilevel structural modulation.

14.
iScience ; 7: 145-153, 2018 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-30267676

RESUMO

Cobalt diselenide (CoSe2) has been demonstrated to be an efficient and economic electrocatalyst for oxygen evolution reaction (OER) both experimentally and theoretically. However, the catalytic performance of up-to-now reported CoSe2-based OER catalysts is still far below commercial expectation. Herein, we report a hybrid catalyst consisting of CoSe2 nanosheets grafted on defective graphene (DG). This catalyst exhibits a largely enhanced OER activity and robust stability in alkaline solution (overpotential at 10 mA cm-2: 270 mV; Tafel plots: 64 mV dec-1). Both experimental evidence and density functional theory calculations reveal that the outstanding OER performance of this hybrid catalyst can be attributed to the synergetic effect of exposed cobalt atoms and carbon defects (electron transfer from CoSe2 layer to defect sites at DG). Our results suggest a promising way for the development of highly efficient and low-cost OER catalysts based on transition metal dichalcogenides.

15.
J Am Chem Soc ; 140(34): 10757-10763, 2018 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-30081632

RESUMO

Platinum (Pt) is the state-of-the-art catalyst for oxygen reduction reaction (ORR), but its high cost and scarcity limit its large-scale use. However, if the usage of Pt reduces to a sufficiently low level, this critical barrier may be overcome. Atomically dispersed metal catalysts with high activity and high atom efficiency have the possibility to achieve this goal. Herein, we report a locally distributed atomic Pt-Co nitrogen-carbon-based catalyst (denoted as A-CoPt-NC) with high activity and robust durability for ORR (267 times higher than commercial Pt/C in mass activity). The A-CoPt-NC shows a high selectivity for the 4e- pathway in ORR, differing from the reported 2e- pathway characteristic of atomic Pt catalysts. Density functional theory calculations suggest that this high activity originates from the synergistic effect of atomic Pt-Co located on a defected C/N graphene surface. The mechanism is thought to arise from asymmetry in the electron distribution around the Pt/Co metal centers, as well as the metal atoms' coordination with local environments on the carbon surface. This coordination results from N8V4 vacancies (where N8 represents the number of nitrogen atoms and V4 indicates the number of vacant carbon atoms) within the carbon shell, which enhances the oxygen reduction reaction via the so-called synergistic effect.

16.
Invest New Drugs ; 36(6): 1147-1157, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30019099

RESUMO

Microtubule as an important target in the cancer therapy was used to design novel tubulin polymerization inhibitors. Sulfanilamide-1,2,3-triazole hybrids were designed by a molecular hybridization strategy and their antiproliferative activity against three selected cancer cell lines (BGC-823, MGC-803 and SGC-7901) were evaluated. All sulfanilamide-1,2,3-triazole hybrids displayed potent inhibitory activity against all cell lines. In particular, compound 10b showed the most excellent inhibitory effect against MGC-803 cells, with an IC50 value of 0.4 µM. Cellular mechanism studies elucidated that 10b induced apoptosis by decreasing the expression level of Bcl-2 and Parp and increasing the expression level of BAX. 10b inhibited the epithelial-mesenchymal transition process by up-regulating E-cadherin and down-regulating N-cadherin. Furthermore, the tubulin polymerization inhibitory activity in vitro of 10b was 2.4 µM. In vivo anticancer assay, 10b effectively inhibited MGC-803 xenograft tumor growth without causing significant loss of body weight. These sulfanilamide-1,2,3-triazole hybrids as potent tubulin polymerization inhibitors might be used as promising candidates for cancer therapy.


Assuntos
Desenho de Fármacos , Polimerização , Sulfanilamida/síntese química , Sulfanilamida/farmacologia , Moduladores de Tubulina/síntese química , Moduladores de Tubulina/farmacologia , Tubulina (Proteína)/metabolismo , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Forma Celular/efeitos dos fármacos , Células Clonais , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , Relação Estrutura-Atividade , Sulfanilamida/química , Moduladores de Tubulina/química , Ensaios Antitumorais Modelo de Xenoenxerto
17.
Small ; 14(26): e1800235, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29726095

RESUMO

Sustainable hydrogen production is an essential prerequisite for realizing the future hydrogen economy. The electrocatalytic hydrogen evolution reaction (HER), as the cornerstone of exploring the mechanism of water electrolysis, has attracted extensive interest in the past decades. Carbon-based materials with significant merits such as abundance, low cost, high conductivity, and tunable molecular structures, are considered as promising candidates for replacing the commercial noble metal electrocatalysts. To date, activity origins of these carbon-based electrocatalysts are mainly attributed to the dopants (e.g., N, B, P or S), whereas the contribution of intrinsic/induced carbon defects has recently been a hot research topic. In this Review, besides the development of heteroatoms doping strategies, the latest studies on defective carbon-based materials for HER electrocatalysis are summarized, especially for various approaches to prepare defective carbons and the detailed introduction regarding the defect catalysis mechanism. Finally, an outlook into the development of future defective carbon-based HER electrocatalysts is presented.

18.
Chem Commun (Camb) ; 53(89): 12140-12143, 2017 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-29075689

RESUMO

A non-precious FeCo nanoparticle decorated defective graphene (DG) sample, DG@FeCo, was successfully synthesized via a facile impregnation method. It is shown that DG@FeCo exhibits similar oxygen reduction reaction activity to that of commercial Pt/C, but has much better durability and is free from methanol poisoning in alkaline electrolytes.

19.
ACS Appl Mater Interfaces ; 9(21): 18295-18304, 2017 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-28488428

RESUMO

Semi-interpenetrated polyvinyl alcohol polymer networks (SIPNs) were prepared by integrating various charged components into polyvinyl alcohol polymer. Contact angle measurement, attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and tensile tests were used to characterize the physicochemical properties of the prepared SIPNs. To investigate the contribution of charges to marine antifouling, the adhesion behaviors of green algae Dunaliella tertiolecta and diatoms Navicula sp. in the laboratory and of the actual marine animals in field test were studied for biofouling assays. The results suggest that less algae accumulation densities are observed for neutral-, anionic-, and zwitterionic-component-integrated SIPNs. However, for the cationic SIPNs, despite the hydration shell induced by the ion-dipole interaction, the resistance to biofouling largely depends on the amount of cationic component because of the possible favorable electrostatic attraction between the cationic groups in SIPNs and the negatively charged algae. Considering that the preparation of novel nontoxic antifouling coating is a long-standing and cosmopolitan industrial challenge, the SIPNs may provide a useful reference for marine antifouling and some other relevant fields.

20.
Adv Mater ; 29(17)2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28256771

RESUMO

Herein, the authors demonstrate a heterostructured NiFe LDH-NS@DG10 hybrid catalyst by coupling of exfoliated Ni-Fe layered double hydroxide (LDH) nanosheet (NS) and defective graphene (DG). The catalyst has exhibited extremely high electrocatalytic activity for oxygen evolution reaction (OER) in an alkaline solution with an overpotential of 0.21 V at a current density of 10 mA cm-2 , which is comparable to the current record (≈0.20 V in Fe-Co-Ni metal-oxide-film system) and superior to all other non-noble metal catalysts. Also, it possesses outstanding kinetics (Tafel slope of 52 mV dec-1 ) for the reaction. Interestingly, the NiFe LDH-NS@DG10 hybrid has also exhibited the high hydrogen evolution reaction (HER) performance in an alkaline solution (with an overpotential of 115 mV by 2 mg cm-2 loading at a current density of 20 mA cm-2 ) in contrast to barely HER activity for NiFe LDH-NS itself. As a result, the bifunctional catalyst the authors developed can achieve a current density of 20 mA cm-2 by a voltage of only 1.5 V, which is also a record for the overall water splitting. Density functional theory calculation reveals that the synergetic effects of highly exposed 3d transition metal atoms and carbon defects are essential for the bifunctional activity for OER and HER.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...