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Gold Supported on Metal Oxides for carbon Monoxide Oxidation

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Nano Research 2011年第2期4卷 180-193页

作者： Sonia A. c. carabineiro Nina Bogdanchikova Miguel Avalos-Borja Alexey Pestryakov pedro B. Tavares Jose L. figueiredo Laboratário de catálise e Materiais Associate Laboratory LSRE/LCM Departamento de Engenharia Química Faculdade de Engenharia Universidade do Porto 4200-465 Porto Portugal Universidad Nacional Autónoma de México Centro de Nanociencias y Nanotecnologia Carretera Tijuana-Ensenada 22800 Ensenada Baja California México Tomsk Polytechnic University 30 Lenin Avenue Tomsk 634050 Russia Universidade de Trás-os-Montes e Alto Douro Centro de Quimica-Vila Real Departamento de Química 5001-911 Vila Real Portugal

Au has been loaded （1% wt.） on different commercial oxide supports （cuO, La2O3, Y2O3, NiO） by three different methods： double impregnation （DIM）, liquid-phase reductive deposition （LPRD）, and ultrasonication （US）. Samples were characterised by N2 adsorption at -196℃, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectrometry, high-angle annular dark-field imaging （Z-contrast）, X-ray diffraction, and temperature programmed reduction. cO oxidation was used as a test reaction to compare the catalytic activities. The best results were obtained with Au loaded by DIM on the NiO support, with an activity of 7.2 × 10^（-4） molco·gAu^（-1）·s^（-1） at room temperature. This is most likely related to the Au nanoparticle size being the smallest in this catalyst （average 4.8 nm）, since it is well known that gold particle size determines the catalytic activity. Other samples, having larger Au particle sizes （in the 2-12 nm range, with average sizes ranging from 4.8 to 6.8 nm）, showed lower activities. Nevertheless, all samples prepared by DIM had activities （from 1.1 × 10^（-4） to 7.2 × 10^（-4） molco·gAu^（-1）·S^（-1）, at room temperature） above those reported in the literature for gold on similar oxide supports. Therefore, this method gives better results than the most usual methods of deposition-precipitation or co-precipitation.

关键词： Gold heterogeneous catalysis oxidation electron diffraction X-ray diffraction

miRNA and platelet genetic machinery

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World Journal of Hematology 2018年第1期7卷 1-3页

作者： pedro c Redondo Department of Physiology Institute of Molecular Pathology Biomarkers University of Extremadura

Platelets are responsible for blood haemostasis. Although anucleate, a complete translational machinery has been found in platelets, which is responsible for new protein generation. Recently, the role of miRNAs in platelets has started to become apparent. In this editorial I highlight this topic in the hope that other scientists may be attracted to work in this area to aid a more complete understanding of protein regulation in platelets and its impact on platelet function.

关键词： Platelets Thrombosis Platelet agonists miRNA

Nucleation and Growth Mechanisms for Pd-Pt Bimetallic Nanodendrites and Their Electrocatalytic Properties

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Nano Research 2010年第2期3卷 69-80页

作者： Byungkwon Lim Majiong Jiang Taekyung Yu pedro H.c.camargo Younan Xia Department of Biomedical Engineering Washington UniversitySt.LouisMissouri 63130USA Department of chemistry Washington UniversitySt.LouisMissouri 63130USA

In a seed-mediated synthesis, nanocrystal growth is often described by assuming the absence of homogeneous nucleation in the solution. Here we provide new insights into the nucleation and growth mechanisms underlying the formation of bimetallic nanodendrites that are characterized by a dense array of Pt branches anchored to a Pd nanocrystal core. These nanostructures can be easily prepared by a one-step, seeded growth method that involves the reduction of K2Ptcl4 by L-ascorbic acid in the presence of 9-nm truncated octahedral Pd seeds in an aqueous solution. Transmission electron microscopy (TEM) and high-resolution TEM analyses revealed that both homogeneous and heterogeneous nucleation of Pt occurred at the very early stages of the synthesis and the Pt branches grew through oriented attachment of small Pt particles that had been formed via homogeneous nucleation. These new findings contradict the generally accepted mechanism for seeded growth that only involves heterogeneous nucleation and simple growth via atomic addition. We have also investigated the electrocatalytic properties of the Pd-Pt nanodendrites for the oxygen reduction and formic acid oxidation reactions by conducting a comparative study with foam-like Pt nanostructures prepared in the absence of Pd seeds under otherwise identical conditions.

关键词： Palladium platinum seeded growth oxygen reduction formic acid oxidation

Elevated nitric oxide and 3',5' cyclic guanosine monophosphate levels in patients with alcoholic cirrhosis

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World Journal of Gastroenterology 2008年第2期14卷 236-242页

作者： cíntia Siqueira Miguel carneiro de Moura Ana Júlia pedro Paula Rocha center of Gastroenterology Institute of Molecular Medicine School of Medicine University of Lisbon Portugal Department of Medicine Ⅱ University Hospital of Santa MariaLisbonPortugal

AIM: To evaluate whether serum levels of nitric oxide (NO ·) and plasma levels of cyclic guanosine monophosphate (cGMP) and total glutathione (GSH) are altered in patients with alcoholic cirrhosis and to examine their correlation with the severity of liver ***: Twenty-six patients with alcoholic liver cirrhosis were studied. Serum levels of NO · and plasma levels of cGMP and GSH were measured in 7 patients with compensated alcoholic cirrhosis (child-Pugh A) and 19 patients with advanced cirrhosis (child-Pugh B and c). The model for end-stage liver disease (MELD) score was evaluated. Sixteen healthy volunteers served as controls. Liver enzymes and creatinine levels were also ***: NO · and cGMP levels were higher in patients with child-Pugh B and c cirrhosis than in child-Pugh A cirrhosis or controls (NO ·: 21.70 ± 8.07 vs 11.70 ± 2.74; 21.70 ± 8.07 vs 7.26 ± 2.47 μmol/L, respectively; P cGMP: 20.12 ± 6.62 vs 10.14 ± 2.78; 20.12 ± 6.62 vs 4.95 ± 1.21 pmol/L, respectively; P child-Pugh B and c cirrhosis than in patients with child-Pugh A cirrhosis or controls (16.04 ± 6.06 vs 23.01 ± 4.38 or 16.04 ± 6.06 vs 66.57 ± 26.23 μmol/L, respectively; P cant correlation between NO · and cGMP levels in all patients with alcoholic cirrhosis. A significant negative correlation between reduced glutathione/glutathione disulfide and the MELD score was found in all cirrhotic ***: Our results suggest a role for oxidative stress in alcoholic liver cirrhosis, which is more significant in decompensated patients with higher levels of NO ·and cGMP and lower GSH levels than in compensated and control patients. Altered mediator levels in decompensated patients may influence the hemodynamic changes in and progression of liver disease.

关键词： Oxidative stress Nitric oxide Alcoholic cirrhosis Fibrosis Model for end-stage liver disease

A call for international research on cOVID-19-induced brain dysfunctions

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National Science Review 2021年第12期8卷 13-14页

作者： pedro A.Valdes-Sosa Alan c.Evans Mitchell J.Valdes-Sosa Mu-ming Poo Global Brain consortium University of Electronic Sciences and Technology of China (UESTC) cuban Neuroscience center (cNEURO) Cuban Academy of Sciences Global Brain consortium Royal Society of CanadaMc Gill Center for Integrative Neuroscience Mc Gill University center for Excellence in Brain Science and Intelligence Technology Institute of NeuroscienceChinese Academy of Sciences

The cOVID-19 pandemic, still raging worldwide, imposes staggering human and economic costs. These will only increase as many convalescent patients suffer consequences for many *** the virus can target multiple organ s...

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A Study on Modeling and Optimization of Memory Systems

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Journal of computer Science & Technology 2021年第1期36卷 71-89页

作者： Jason Liu pedro Espina Xian-He Sun School of computing and Information Sciences Florida International UniversityMiamiFL 33199U.S.A Department of computer Science Illinois Institute of TechnologyChicagoIL 60616U.S.A

Accesses Per cycle(APc),concurrent Average Memory Access Time(c-AMAT),and Layered Performance Matching(LPM)are three memory performance models that consider both data locality and memory assess *** APc model measures the throughput of a memory architecture and therefore reflects the quality of service(QoS)of a memory *** c-AMAT model provides a recursive expression for the memory access delay and therefore can be used for identifying the potential bottlenecks in a memory *** LPM method transforms a global memory system optimization into localized optimizations at each memory layer by matching the data access demands of the applications with the underlying memory system *** three models have been proposed separately through prior *** paper reexamines the three models under one coherent mathematical *** specifically,we present a new memorycentric view of data *** divide the memory cycles at each memory layer into four distinct categories and use them to recursively define the memory access latency and concurrency along the memory *** new perspective offers new insights with a clear formulation of the memory performance considering both locality and ***,the performance model can be easily understood and applied in engineering *** such,the memory-centric approach helps establish a unified mathematical foundation for model-driven performance analysis and optimization of contemporary and future memory systems.

关键词： performance modeling performance optimization memory architecture memory hierarchy concurrent average memory access time

Highly Efficient and Selective Photocatalytic Nonoxidative coupling of Methane to Ethylene over Pd-Zn Synergistic catalytic Sites

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Research 2023年第1期2022卷 485-496页

作者： Yanduo Liu Yihong chen Wenbin Jiang Tingting Kong pedro H.c.camargo chao Gao Yujie Xiong School of chemistry and Materials Science University of Science and Technology of ChinaHefeiAnhui 230026China PInstitute of Energy Hefei comprehensive National Science center HefeiAnhui230031China Key Laboratory of Functional Molecular Solids Ministry of EducationAnhui Engineering Research Center of Carbon Neutrality College of Chemistry and Materials ScienceAnhui Normal UniversityWuhuAnhui 241000China ADepartment of chemistry University of HelsinkiFIN-00014Finland

Photocatalytic nonoxidative coupling of cH_(4)to multicarbon(c^(2+))hydrocarbons(e.g.,c,H4)and H,under ambient conditions provides a promising energy-conserving approach for utilization of carbon ***,as the methyl intermediates prefer to undergo self-coupling to produce ethane,it is a challenging task to control the selective conversion of cH to higher valueadded ***,we adopt a synergistic catalysis strategy by integrating Pd-Zn active sites on visible light-responsive defective WO_(3)nanosheets for synergizing the adsorption,activation,and dehydrogenation processes in cH_(4)to c_(2)H_(4)*** from the synergy,our model catalyst achieves a remarkable c^(2+)compounds yield of 31.85μmolgh with an exceptionally high c,H4 selectivity of 75.3%and a stoichiometric H_(2)*** situ spectroscopic studies reveal that the Zn sites promote the adsorption and activation of cH_(4)molecules to generate methyl and methoxy intermediates with the assistance of lattice oxygen,while the Pd sites facilitate the dehydrogenation of methoxy to methylene radicals for producing c_(2)H_(4)and suppress *** work demonstrates a strategy for designing efficient photocatalysts toward selective coupling of cH_(4)to higher value-added chemicals and highlights the importance of synergistic active sites to the synergy of key steps in catalytic reactions.

关键词： oxidative synergistic coupling

High-throughput analysis of Fröhlich-type polaron models

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npj computational Materials 2023年第1期9卷 817-829页

作者： pedro Miguel M.c.de Melo Joao c.de Abreu Bogdan Guster Matteo Giantomassi Zeila Zanolli Xavier Gonze Matthieu J.Verstraete chemistry Department Debye Institute for Nanomaterials Science and European Theoretical Spectroscopy FacilityCondensed Matter and InterfacesUtrecht UniversityPO Box 80.0003508 TA UtrechtThe Netherlands Nanomat/Q-MAT/cESAM and European Theoretical Spectroscopy Facility Universitéde LiègeB-4000 LiègeBelgium UcLouvain Institute of Condensed Matter and Nanosciences(IMCN)Chemin desÉtoiles 8B-1348 Louvain-la-NeuveBelgium

The electron–phonon interaction is central to condensed matter,*** electrical resistance,superconductivity or the formation of polarons,and has a strong impact on observables such as band gaps or optical *** most common framework for band energy corrections is the Fröhlich model,which often agrees qualitatively with experiments in polar materials,but has limits for complex cases.A generalized version includes anisotropic and degenerate electron bands,and multiple *** this work,we identify trends and outliers for the Fröhlich models on 1260 *** test the limits of the Fröhlich models and their perturbative treatment,in particular the large polaron *** our extended dataset most materials host perturbative large polarons,but there are many instances that are non-perturbative and/or localize on distances of a few bond *** find a variety of behaviors,and analyze extreme cases with huge zero-point renormalization using the first-principles Allen-Heine-cardona approach.

关键词： materials polaron correction

On the Restricted Arc-connectivity of s-geodetic Digraphs

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Acta Mathematica Sinica,English Series 2010年第10期26卷 1865-1876页

作者： camino BALBUENA pedro GARcíA-VZQUEZ Departament de Matemàtica Aplicada Ⅲ Universitat Politècnica de Catalunya Departamento de Matemática Aplicada I Universidad de Sevilla E.T.S. de Arquitectura

For a strongly connected digraph D the minimum ,cardinality of an arc-cut over all arc-cuts restricted arc-connectivity λ′（D） is defined as the S satisfying that D - S has a non-trivial strong component D1 such that D - V（D1） contains an arc. Let S be a subset of vertices of D. We denote by w＋（S） the set of arcs uv with u ∈ S and v S, and by w-（S） the set of arcs uv with u S and v ∈ S. A digraph D = （V, A） is said to be λ′-optimal if λ′（D） =ξ′（D）, where ξ′（D） is the minimum arc-degree of D defined as ξ（D） = min {ξ′（xy）： xy ∈ A}, and ξ′（xy） = min（｜ω＋（{x,y}）｜, ｜w-（{x,y}）｜, ｜w＋（x） ∪ w- （y）｜, ｜w- （x） ∪ω＋（y）｜}. In this paper a sufficient condition for a s-geodetic strongly connected digraph D to be λ′-optimal is given in terms of its diameter. Furthermore we see that the h-iterated line digraph Lh（D） of a s-geodetic digraph is λ′-optimal for certain iteration h.

关键词： Restricted arc-connectivity arc-cut diameter s-geodetic digraph line digraph