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1.
J Am Chem Soc ; 141(38): 14976-14980, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31523954

RESUMO

The traditional NH3 production method (Haber-Bosch process) is currently complemented by electrochemical synthesis at ambient conditions, but the rather low selectivity (as indicated by the Faradaic efficiency) for the electrochemical reduction of molecular N2 into NH3 impedes the progress. Here, we present a powerful method to significantly boost the Faradaic efficiency of Au electrocatalysts to 67.8% for the nitrogen reduction reaction (NRR) by increasing their electron density through the construction of inorganic donor-acceptor couples of Ni and Au nanoparticles. The unique role of the electron-rich Au centers in facilitating the fixation and activation of N2 was also investigated via theoretical simulation methods and then confirmed by experimental results. The highly coupled Au and Ni nanoparticles supported on nitrogen-doped carbon are stable for reuse and long-term performance of the NRR, making the electrochemical process more sustainable for practical application.

2.
ChemSusChem ; 11(14): 2306-2309, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-29851293

RESUMO

Electrochemical gas evolution and activation reactions are complicated processes, involving not only active electrocatalysts but also the interaction among solid electrodes, electrolyte, and gas-phase products and reactants. In this study, multiphase interfaces of superadsorbing graphene-based electrodes were controlled without changing the active centers to significantly facilitate mass diffusion kinetics for superior performance. The achieved in-depth understanding of how to regulate the interfacial properties to promote the electrochemical performance could provide valuable clues for electrode manufacture and for the design of more active electrocatalysts.

3.
Angew Chem Int Ed Engl ; 57(10): 2697-2701, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29341380

RESUMO

Engineering the adsorption of molecules on active sites is an integral and challenging part for the design of highly efficient transition-metal-based catalysts for methanol dehydrogenation. A Mott-Schottky catalyst composed of Ni nanoparticles and tailorable nitrogen-doped carbon-foam (Ni/NCF) and thus tunable adsorption energy is presented for highly efficient and selective dehydrogenation of gas-phase methanol to hydrogen and CO even under relatively high weight hourly space velocities (WHSV). Both theoretical and experimental results reveal the key role of the rectifying contact at the Ni/NCF boundaries in tailoring the electron density of Ni species and enhancing the absorption energies of methanol molecules, which leads to a remarkably high turnover frequency (TOF) value (356 mol methanol mol-1 Ni h-1 at 350 °C), outpacing previously reported bench-marked transition-metal catalysts 10-fold.

4.
J Am Chem Soc ; 139(2): 811-818, 2017 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-28006898

RESUMO

Heterogeneous catalysts of inexpensive and reusable transition-metal are attractive alternatives to homogeneous catalysts; the relatively low activity of transition-metal nanoparticles has become the main hurdle for their practical applications. Here, the de novo design of a Mott-Schottky-type heterogeneous catalyst is reported to boost the activity of a transition-metal nanocatalyst through electron transfer at the metal/nitrogen-doped carbon interface. The Mott-Schottky catalyst of nitrogen-rich carbon-coated cobalt nanoparticles (Co@NC) was prepared through direct polycondensation of simple organic molecules and inorganic metal salts in the presence of g-C3N4 powder. The Co@NC with controllable nitrogen content and thus tunable Fermi energy and catalytic activity exhibited a high turnover frequency (TOF) value (8.12 mol methyl benzoate mol-1 Co h-1) for the direct, base-free, aerobic oxidation of benzyl alcohols to methyl benzoate; this TOF is 30-fold higher than those of the state-of-the-art transition-metal-based nanocatalysts reported in the literature. The presented efficient Mott-Schottky catalyst can trigger the synthesis of a series of alkyl esters and even diesters in high yields.

5.
J Vet Sci ; 15(3): 399-407, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24675838

RESUMO

A recombinant replication-defective adenovirus expressing the major epitopes of porcine circovirus-2 (PCV-2) capsid protein (rAd/Cap/518) was previously constructed and shown to induce mucosal immunity in mice following intranasal delivery. In the present study, immune responses induced by intranasal immunization with a combination of rAd/Cap/518 and cytosine-phosphate-guanosine oligodeoxynucleotides (CpG ODN) were evaluated in mice. The levels of PCV-2-specific IgG in serum and IgA in saliva, lung, and intestinal fluids were significantly higher in the group immunized with rAd/Cap/518 and CpG ODN than animals immunized with rAd/Cap/518 alone. The frequencies of IL-2-secreting CD4⁺ T cells and IFN-γ-producing CD8⁺ T cells were significantly higher in the combined immunization group than mice immunized with rAd/Cap/518 alone. The frequencies of CD3⁺, CD3⁺CD4⁺CD8⁻, and CD3⁺CD4⁻CD8⁺ T cells in the combined immunization group were similar to that treated with CpG ODN alone, but significantly higher than mice that did not receive CpG ODN. PCV-2 load after challenge in the combined immunization group was significantly lower than that in the phosphate-buffered saline placebo group and approximately 7-fold lower in the group treated with CpG ODN alone. These results indicate that rAd/Cap/518 combined with CpG ODN can enhance systemic and local mucosal immunity in mice, and represent a promising synergetic mucosal vaccine against PCV-2.


Assuntos
Proteínas do Capsídeo/genética , Infecções por Circoviridae/imunologia , Circovirus/genética , Vacinas Virais/genética , Adenoviridae/genética , Adenoviridae/imunologia , Administração Intranasal , Animais , Proteínas do Capsídeo/imunologia , Circovirus/imunologia , Epitopos/genética , Epitopos/imunologia , Feminino , Imunidade nas Mucosas/imunologia , Imunoglobulina A/sangue , Imunoglobulina A/imunologia , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Oligodesoxirribonucleotídeos/genética , Vacinas Sintéticas/genética , Vacinas Sintéticas/imunologia , Vacinas Virais/administração & dosagem , Vacinas Virais/imunologia
6.
J Genet ; 92(2): 281-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23970084

RESUMO

The study of 1000-grain weight (TGW) and percentage of grains with chalkiness (PGWC) is very important in rice. In this study, a set of introgression lines (ILs), derived from Sasanishiki/Habataki with Sasanishiki as the recurrent parent, were used to detect correlations and quantitative trait loci (QTL) on TGW and PGWC in two different environments. Phenotypic correlation analysis showed that there was no significant correlation between TGW and PGWC in both environments, which indicated that the linkage of TGW and PGWC traits could be broken via suitable population. A total of 20 QTL were detected in both environments, nine QTL for 1000-paddy-grain weight (PTGW), five QTL for 1000-brown-grain weight (BTGW) and six QTL for percentage of grains with chalkiness (PGWC). Moreover, five QTL, qPTGW3, qPTGW8.2, qPTGW11.1 for PTGW and qPGWC1.1, qPGWC1.2 for PGWC, were stably expressed in both environments. Phenotypic values were significantly different (P < 0.01) between the introgression lines carrying these five QTL alleles and the genetic background parent, Sasanishiki. The introgression lines carrying these QTL also represent a useful genetic resource in the context of rice yield and quality improvement via a design-breeding approach.


Assuntos
Mapeamento Cromossômico , Oryza/crescimento & desenvolvimento , Oryza/genética , Locos de Características Quantitativas , Cruzamentos Genéticos , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Ligação Genética , Valor Nutritivo/genética , Fenótipo , Melhoria de Qualidade
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