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ecent advances in selective acetylene hydrogenation using palladium containing catalysts

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Frontiers of Chemical Science and Engineering 2015年第2期9卷 142-153页

作者： Alan j. McCue james A. Anderson Surface Chemistry and Catalysis Group Department of Chemistry University of Aberdeen Aberdeen AB24 3UE UK Materials and Chemical Engineering Group School of Engineering University of Aberdeen Aberdeen AB24 3UE UK

Recent advances with Pd containing catalysts for the selective hydrogenation of acetylene are described. The overview classifies enhancement of catalytic proper- ties for monometallic and bimetallic Pd catalysts. Activity/ selectivity of Pd catalysts can be modified by controllingparticle shape/morphology or immobilisation on a support which interacts strongly with Pd particles. In both cases enhanced ethylene selectivity is generally associated with modifying ethylene adsorption strength and/or changes to hydride formation. Inorganic and organic selectivity modifiers （i.e., species adsorbed onto Pd particle surface） have also been shown to enhance ethylene selectivity. Inorganic modifiers such as TiO2 change Pd ensemble size and modify ethylene adsorption strength whereas organic modifiers such as diphenylsulfide are thought to create a surface template effect which favours acetylene adsorption with respect to ethylene. A number of metals and synthetic approaches have been explored to prepare Pd bimetallic catalysts. Examples where enhanced selectivity is observed are generally associated with decreased Pd ensemble size and/or hindering of the ease with which an unselective hydride phase is formed for Pd. A final class of bimetallic catalysts are discussed where Pd is not thought to be the primary reaction site but merely acts as a site where hydrogen dissociation and spillover occurs onto a second metal （Cu or Au） where the reaction takes place more selectively.

关键词： acetylene ethylene selective hydrogenation,palladium bimetallic

HEALTHCARE: A COMPLEX SERVICE SYSTEM

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journal of Systems Science and Systems Engineering 2009年第3期18卷 257-282页

作者： james M. TIEN Pascal j. GOLDSCHMIDT-CLERMONT Dean College of Engineering University of Miami Coral GablesFlorida USA Dean Miller School of Medicine University of Miami Coral GablesFlorida USA

Healthcare is indeed a complex service system, one requiring the technobiology approach of systems engineering to underpin its development as an integrated and adaptive system. In general, healthcare services are carried out with knowledge-intensive agents or components which work together as providers and consumers to create or co-produce value. Indeed, the engineering design of a healthcare system must recognize the fact that it is actually a complex integration of human-centered activities that is increasingly dependent on information technology and knowledge. Like any service system, healthcare can be considered to be a combination or recombination of three essential components - people （characterized by behaviors, values, knowledge, etc.）, processes （characterized by collaboration, customization, etc.） and products （characterized by software, hardware, infrastructures, etc.）. Thus, a healthcare system is an integrated and adaptive set of people, processes and products. It is, in essence, a system of systems which objectives are to enhance its efficiency （leading to greater interdependency） and effectiveness （leading to improved health）. Integration occurs over the physical, temporal, organizational and functional dimensions, while adaptation occurs over the monitoring, feedback, cybernetic and learning dimensions. In sum, such service systems as healthcare are indeed complex, especially due to the uncertainties associated with the human-centered aspects of these systems. Moreover, the system complexities can only be dealt with methods that enhance system integration and adaptation.

关键词： Services healthcare system integration system adaptation system complexity system of systems customization co-production decision informatics real-time decision making

Comparative study of well soaking timing(pre *** flowback)for water blockage removal from matrix-fracture interface

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Petroleum 2020年第3期6卷 286-292页

作者： Nur Wijaya james j.Sheng Bob L.Herd Department of Petroleum Engineering Texas Tech UniversityTexasUSA

Water blockage after hydraulic fracturing is one of the major challenges in shale oil recovery which affects the optimal production from the *** water blockage represents a higher water saturation near the matrixfracture interface,which decreases the hydrocarbon relative *** removal of water blockage in the field is typically carried out by soaking the well(i.e.,shut-in)after hydraulic fracturing operation is *** soaking period allows water redistribution,which decreases the water saturation near the matrix-fracture ***,previous field reports show that there is not a strong consensus on whether shut-in is beneficial in terms of production rate or ultimate oil *** to the large number of parameters involved in hydraulic fracturing and tight formations,it is challenging to select which parameter plays the dominant role in determining the shut-in ***,literature on field case studies does not frequently report the parameters which are of researchers’*** other words,the challenge of evaluating shut-in performance not only lies on the complexity of parameters and effects involved within the reservoir,but also the limited number of field case studies which report a comprehensive list of fracturing and reservoir *** paper aims to investigate the effect of well soaking timing on shut-in *** idea to investigate the shut-in timing effect is motivated by the fact that in the field,shut-in can take place either immediately after hydraulic fracturing but before the first flowback(i.e.,pre-flowback)or sometime after the first flowback(i.e.,post-flowback).The timing of shut-in is believed to influence the production performance,because it dictates how much water is allowed to imbibe from the fractures to the matrix before the extended production.A numerical model is built and validated by a successful history match with numerous data from core-flood *** previous s

关键词： Water blockage Formation damage Flowback Shut-in Desiccation

Cortico-centric effects of general anesthetics on cerebrocortical evoked potentials

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Neuroscience Bulletin 2015年第6期31卷 697-704页

作者： Logan j.Voss james W.Sleigh Anaesthesia Department Waikato District Health Board University of Auckland Waikato Clinical School

Despite their ubiquitous use for rendering patients unconscious for surgery, our understanding of how general anesthetics cause hypnosis remains rudimentary at best. Recent years have seen increased interest in ＂top-down＂ cortico-centric theories of anesthetic action. The aim of this study was to explore this by investigating direct cortical effects of anesthetics on cerebrocortical evoked potentials in isolated mouse brain slices. Evoked potentials were elicited in cortical layer IV by electrical stimulation of the underlying white matter. The effects of three anesthetics （ketamine, etomidate, and isoflurane） on the amplitude, latency, and slope of short-latency evoked potentials were quantified. The N2/P3/N4 potentials - which represent the early cortical response - were enhanced by etomidate （increased P3-N4 slope, P 〈0.01）, maintained by ketamine, and reduced by isoflurane （lower N2/P3 amplitude, P 〈0.01）. These effects closely resemble those seen in vivo for the same drugs and point to a cortical mechanism independent of effects on subcortical structures such as the thalamus.

关键词： anesthesia evoked potentials corticalslice thalamus

Flu channel drug resistance:a tale of two sites

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Protein & Cell 2010年第3期1卷 246-258页

作者： Rafal M.Pielak james j.Chou Department of Biological Chemistry and Molecular Pharmacology Harvard Medical SchoolBostonMA 02115USA Program in Biological and Biomedical Sciences Harvard Medical SchoolBostonMA 02115USA

The M2 proteins of influenza A and B virus,AM2 and BM2,respectively,are transmembrane proteins that oligomerize in the viral membrane to form proton-selective *** conductance of the M2 proteins is required for viral replication;it is believed to equilibrate pH across the viral membrane during cell entry and across the trans-Golgi membrane of infected cells during viral *** addition to the role of M2 in proton conductance,recent mutagenesis and structural studies suggest that the cytoplasmic domains of the M2 proteins also play a role in recruiting the matrix proteins to the cell surface during virus *** viral ion channels of minimalist architecture,the membrane-embedded channel domain of M2 has been a model system for investigating the mechanism of proton ***,as a proven drug target for the treatment of influenza A infection,M2 has been the subject of intense research for developing new anti-flu ***2 is the target of two anti-influenza A drugs,amantadine and rimantadine,both belonging to the adamantane class of ***,resistance of influenza A to adamantane is now widespread due to mutations in the channel domain of *** review summarizes the structure and function of both AM2 and BM2 channels,the mechanism of drug inhibition and drug resistance of AM2,as well as the development of new M2 inhibitors as potential anti-flu drugs.

关键词： M2 BM2 influenza proton channel amantadine rimantadine

Evaluating the Effects of Graviton Redshift upon Spiral Galaxy Rotation Curves, Surface Brightness Magnitudes and Gravitational Lensing

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journal of High Energy Physics, Gravitation and Cosmology 2024年第3期10卷 967-985页

作者： Firmin j. Oliveira East Asian Observatory James Clerk Maxwell Submillimetre Telescope Hilo USA

The effects of the gravitational redshift of gravitons upon spiral galaxy rotation energy are compared to the standard mass to light analyses in obtaining rotation curves. The derivation of the total baryonic matter compares well with the standard theory and the rotation velocity is matched to a high precision. The stellar mass distributions obtained from the fit with graviton energy loss are used to derive the surface brightness magnitudes for the galaxies, which agree well with the observed measurements. In a new field of investigation, the graviton theory is applied to the observations of gravitational lenses. The results of these applications of the theory suggest that it can augment the standard methods and may eliminate the need for dark matter.

关键词： Gravitons Gravitational Redshift Surface Brightness Gravitational Lens Lens Mass

Effect of calcination temperature on steam reforming activity of Ni-based pyrochlore catalysts

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journal of Rare Earths 2020年第7期38卷 711-718,I0002页

作者： Daniel j.Haynes Dushyant Shekhawat David Berry Amitava Roy james j.Spivey National Energy Technology Laboratory U.S.Department of Energy3610 Collins Ferry RdMorgantownWV26507 USA Louisiana State University Cain Department of Chemical Engineering3307 Patrick Taylor HallBaton RougeLA70803USA

This work served as the second part of a study evaluating the effect of calcination temperature(700-1000℃) on Ni-based lanthanum zirconate pyrochlore catalysts for methane steam reforming.A previous study(Haynes et ***.2017(43) 16744) provided a thorough characterization of the material properties for the catalysts used here,and this study focuses on the evaluation of catalytic *** activity was assessed by two different experimental studies:the effect of reaction temperature using a temperature programmed surface reaction(TPSR),and the effect of reaction *** results demonstrate a complex interaction between the Ni particles and surface LaOx species under the methane steam reforming ***,the material calcined at the lowest temperature(700℃) possesses the highest activity and selectivity,which is attributed to smaller and more welldispersed Ni particles on the surface,and,more importantly,a lesser degree La enrichment at the *** catalysts were deactivated by steam to NiO under all conditions tested,but at certain low reaction pressure(p=0.23 MPa) conditions the materials calcined at 700-900℃ are able to completely recover equilibrium activity in-situ that is then robust and stable under both low and high reaction pressures(p=1.8 MPa) suggesting the formation of a synergistic relationship between Ni and La for syngas ***,exposure of a fresh material to high reaction pressures leads to a rapid and irreversible loss in both CH4 conversion and syngas selectivity whether in the fresh(no pretreatment),or pretreated(steam,H2 or Ar only at 800℃) form for any *** mechanism for deactivation appears to be due to the presence of LaOx species that become mobile,possibly by the formation of La-OH,and covers the active Ni particles and inhibits sites responsible for the CH4 decomposition.

关键词： Nickel Pyrochlore Methane Steam reforming Catalyst Lanthanum enrichment

Hydrogen for a Net-Zero Carbon World

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Engineering 2023年第10期29卷 8-10页

作者： Nigel P.Brandon james j.Brandon Faculty of Engineering Imperial College LondonSouth Kensington CampusLondon SW72AZUK The First Element Ltd. London N17GUUK

*** hydrogen?The concept of the“hydrogen economy”was first coined by *** Bockris during a talk he gave in 1970 at the General Motors Technical ***’s talk introduced the vision of a world economy in which energy was... 详细信息

关键词： hydrogen Carbon economy

Further discussion of CO_(2) huff-n-puff mechanisms in tight oil reservoirs based on NMR monitored fluids spatial distributions

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Petroleum Science 2023年第1期20卷 350-361页

作者： Wei-Yu Tang james j.Sheng Ting-Xue jiang Unconventional Petroleum Research Institute China University of PetroleumBeijing102249China Bob L.Herd Department of Petroleum Engineering Texas Tech UniversityLubbockTX79409USA Sinopec Research Institute of Petroleum Engineering Beijing100101China

Due to the poor physical properties of tight reservoirs,CO_(2) huff-n-puff(HNP)is considered a potential enhanced oil recovery(EOR)method after primary *** plays a critical role in the effective implementation of CO_(2) *** the optimization requires a good understanding of the EOR *** this work,the spatial distribution of oil saturation under different experimental conditions was analyzed by the NMR method to further discuss the HNP *** to the variation of 1D frequency signal amplitude,we divided the core into the hardly movable area and movable area,the region with the obvious signal decline was defined as the movable area,and the hardly movable area was the region with limited signal *** on that the recovery characteristics of different scenarios were ***,the necessity of the soaking stage was studied,where three scenarios with different soaking times were carried ***,the injection pressure was adjusted to investigate the effect of the pressure *** T_(2) spectra show that soaking has significantly improved the production of crude oil in small pores,and higher oil recovery in a single cycle is observed,but it is lower when the elapsed time(total operation time)is the same.31.03% of oil can be recovered after 3 cycles HNP,which increases to 33.8% and 37.06% for the 4 cycles and 6 cycles *** the pressure gradient increases,more oil is removed out of the matrix,and the oil in the deep part of the reservoir can be effectively *** the CO_(2) huff-n-puff process,the oil distributions are similar to the solution gas drive,the residual oil is distributed at the close end of the core and the range that the oil can be efficiently recovered is limited.

关键词： Tight reservoirs Low-field nuclear magnetic resonance (NMR) CO_(2)huff-n-puff Enhanced oil recovery