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Nat Nanotechnol ; 14(11): 1071-1074, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31611657


We demonstrate the translation of a low-cost, non-precious metal cobalt phosphide (CoP) catalyst from 1 cm2 lab-scale experiments to a commercial-scale 86 cm2 polymer electrolyte membrane (PEM) electrolyser. A two-step bulk synthesis was adopted to produce CoP on a high-surface-area carbon support that was readily integrated into an industrial PEM electrolyser fabrication process. The performance of the CoP was compared head to head with a platinum-based PEM under the same operating conditions (400 psi, 50 °C). CoP was found to be active and stable, operating at 1.86 A cm-2 for >1,700 h of continuous hydrogen production while providing substantial material cost savings relative to platinum. This work illustrates a potential pathway for non-precious hydrogen evolution catalysts developed in past decades to translate to commercial applications.

Sci Rep ; 5: 12220, 2015 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-26191776


We evaluated the activities of well-defined Ru@Pt core-shell nanocatalysts for hydrogen evolution and oxidation reactions (HER-HOR) using hanging strips of gas diffusion electrode (GDE) in solution cells. With gas transport limitation alleviated by micro-porous channels in the GDEs, the charge transfer resistances (CTRs) at the hydrogen reversible potential were conveniently determined from linear fit of ohmic-loss-corrected polarization curves. In 1 M HClO4 at 23 °C, a CTR as low as 0.04 Ω cm(-2) was obtained with only 20 µg cm(-2) Pt and 11 µg cm(-2) Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio. Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol(-1). Using the Ru@Pt catalyst with total metal loadings <50 µg cm(-2) for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm(-2) Pt black.

J Gen Virol ; 95(Pt 8): 1755-1769, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24824860


Kaposi's sarcoma-associated herpesvirus (KSHV) capsids can be produced in insect cells using recombinant baculoviruses for protein expression. All six capsid proteins are required for this process to occur and, unlike for alphaherpesviruses, the small capsid protein (SCP) ORF65 is essential for this process. This protein decorates the capsid shell by virtue of its interaction with the capsomeres. In this study, we have explored the SCP interaction with the major capsid protein (MCP) using GFP fusions. The assembly site within the nucleus of infected cells was visualized by light microscopy using fluorescence produced by the SCP-GFP polypeptide, and the relocalization of the SCP to these sites was evident only when the MCP and the scaffold protein were also present - indicative of an interaction between these proteins that ensures delivery of the SCP to assembly sites. Biochemical assays demonstrated a physical interaction between the SCP and MCP, and also between this complex and the scaffold protein. Self-assembly of capsids with the SCP-GFP polypeptide was evident. Potentially, this result can be used to engineer fluorescent KSHV particles. A similar SCP-His6 polypeptide was used to purify capsids from infected cell lysates using immobilized affinity chromatography and to directly label this protein in capsids using chemically derivatized gold particles. Additional studies with SCP-GFP polypeptide truncation mutants identified a domain residing between aa 50 and 60 of ORF65 that was required for the relocalization of SCP-GFP to nuclear assembly sites. Substitution of residues in this region and specifically at residue 54 with a polar amino acid (lysine) disrupted or abolished this localization as well as capsid assembly, whereas substitution with non-polar residues did not affect the interaction. Thus, this study identified a small conserved hydrophobic domain that is important for the SCP-MCP interaction.

Proteínas do Capsídeo/metabolismo , Herpesvirus Humano 8/fisiologia , Proteínas Virais/metabolismo , Montagem de Vírus , Animais , Linhagem Celular , Análise Mutacional de DNA , Ligação Proteica , Estrutura Terciária de Proteína , Transporte Proteico , Spodoptera
J Virol ; 86(21): 11926-30, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22915821


Self-assembly of Kaposi's sarcoma-associated herpesvirus capsids occurs when six proteins are coexpressed in insect cells using recombinant baculoviruses; however, if the small capsid protein (SCP) is omitted from the coinfection, assembly does not occur. Herein we delineate and identify precisely the assembly domain and the residues of SCP required for assembly. Hence, six residues, R14, D18, V25, R46, G66, and R70 in the assembly domain, when changed to alanine, completely abolish or reduce capsid assembly.

Herpesvirus Humano 8/genética , Herpesvirus Humano 8/fisiologia , Domínios e Motivos de Interação entre Proteínas , Proteínas Virais/genética , Proteínas Virais/metabolismo , Montagem de Vírus , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Baculoviridae , Linhagem Celular , Vetores Genéticos , Microscopia Eletrônica , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Alinhamento de Sequência , Vírion/ultraestrutura