检索结果-南通市图书馆

Engineering operando methodology： Understanding catalysis in time and space

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2018年第3期12卷 509-536页

作者： Raquel Portela Susana Perez-Ferreras Ana Serrano-Lotina Miguel A. Banares Instituto de Catalisis y Petroleoquimica ICP-CSIC Marie Curie 2 Madrid Spain

The term operando was coined at the begin- ning of this century to gather the growing efforts devoted to establish structure-activity relationships by simulta- neously characterizing a catalyst performance and the relevant surface chemistry during genuine catalytic opera- tion. This approach is now widespread and consolidated; it has become an increasingly complex but efficient junction where spectroscopy, materials science, catalysis and engineering meet. While for some characterization techni- ques kinetically relevant reactor cells with good resolution are recently developing, the knowledge gained with magnetic resonance and X-ray and vibrational spectro- scopy studies is already huge and the scope of operando methodology with these techniques is recently expanding from studies with small amounts of powdered solids to more industrially relevant catalytic systems. Engineering catalysis implies larger physical domains, and thus all sort of gradients. Space- and time- resolved multi-technique characterization of both the solid and fluid phases involved in heterogeneous catalytic reactions （including temperature data） is key to map processes from different perspectives, which allows taking into account existing heterogeneities at different scales and facing up- and down-scaling for applications ranging from microstructured reactors to industrial-like macroreactors （operating with shaped catalytic bodies and/or in integral regime）. This work reviews how operando methodology is evolving toward engineered reaction systems.

关键词： operando structured catalysts spaceresolved time-resolved spectroscopy

Conservation Tillage Influence on Carbon Dynamics Under Mediterranean Conditions

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2014年第1期24卷 65-75页

作者： R.LóPEZ-GARRIDO E.MADEJON F.MORENO J.M.MURILLO Instituto de Recursos Naturales y Agrobiologia de Sevilla(IRNAS-csic)

Intensity of tillage practices can enhance organic matter decomposition, increasing CO2 emissions from soil to the atmosphere. Conservation tillage （CT） has been proposed as a means of counteracting potential damages to the environment. In this study the effects of two CT systems, reduced tillage in a long-term experiment （RTL） and no-tillage in a short-term experiment （NTs）, were compared to traditional tillage （TT） in the long （TTL） and short-term experiments （TTs）. CO2 fluxes, total soil organic carbon （SOC） and dehydrogenase activity （DHA） were evaluated at 0-5, 5-10 and 10-15 cm depths throughout the three years studied （Oct. 2006 Jul. 2009）. Traditional tillage increased C02 emissions compared to CT. The CT treatments （RTL and NTs） accumulated more SOC in the surface layer （0 5 cm） than the TT treatments （TTL and TTs）. SOC accumulation was moderate but DHA consistently increased in CT in the surface soil, especially with a legume crop included in the crop rotation. Values of stratification ratio of all parameters studied were higher in the CT treatments （RTL and NTs）. The agricultural and environmental benefits derived from CT make this system recommendable for semi-arid Mediterranean rain-fed agriculture.

关键词： crop rotation dehydrogenase activity rain-fed agriculture soil organic carbon

Enzymatic and chemo-enzymatic strategies to produce highly valuable chiral amines from biomass with ω-transaminases on 2D zeolites

在线全文

学校读者我要写书评

暂无评论

National Science Review 2022年第9期9卷 10-18页

作者： J.Miguel Carceller Karen S.Arias Maria J.Climent Sara Iborra Avelino Corma Instituto de Tecnologia Química (UPV-csic) Universitat Politècnica de València

Amino transaminases(ATAs) have been supported on a 2D ITQ-2 zeolite through electrostatic interactions, resulting in a highly stable active biocatalyst to obtain a variety of valuable chiral amines starting from prochiral ketones derived from biomass. We have extended the biocatalyst applications by designing a chemo-enzymatic process that allows, as the first step, prochiral ketones to be obtained from biomass-derived compounds through an aldol condensation–reduction step using a bifunctional metal/base catalyst. The prochiral ketone is subsequently converted into the chiral amine using the immobilized ATA. We show that it is feasible to couple both steps in a semi-continuous process to produce industrially relevant chiral amines with yields of >95% and ～100% enantiomer excess.

关键词： amino transaminase ITQ-2 zeolite chemo-enzymatic process biomass semi-continuous process Pd/MgO

Emergence of mass in the gauge sector of QCD

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2022年第11期46卷 22-44页

作者： J.Papavassiliou Department of Theoretical Physics and IFIC University of Valencia and CSICE-46100ValenciaSpain

It is currently widely accepted that gluons,while massless at the level of the fundamental QCD Lagrangian,acquire an effective mass through the non-Abelian implementation of the classic Schwinger *** key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the *** poles enter the evolution equation of the gluon propagator and nontrivially affect the way the Slavnov-Taylor identities of the vertices are resolved,inducing a smoking-gun displacement in the corresponding Ward *** this article,we present a comprehensive review of the pivotal concepts associated with this dynamical scenario,emphasizing the synergy between functional methods and lattice simulations and highlighting recent advances that corroborate the action of the Schwinger mechanism in QCD.

关键词： non perturbative QCD Schwinger-Dyson equations Schwinger functions

Design and Robust Performance Evaluation of a Fractional Order PID Controller Applied to a DC Motor

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2017年第2期4卷 304-314页

作者： J.Viola L.Angel J.M.Sebastian Universidad Pontificia Bolivariana Universidad Politecnica de Madrid Centre for Automation and Robotics (CAR) UPM-CSIC

This paper proposes a methodology for the quantitative robustness evaluation of PID controllers employed in a DC motor. The robustness analysis is performed employing a 2~3 factorial experimental design for a fractional order proportional integral and derivative controller(FOPID), integer order proportional integral and derivative controller(IOPID)and the Skogestad internal model control controller(SIMC). The factors assumed in experiment are the presence of random noise,external disturbances in the system input and variable load. As output variables, the experimental design employs the system step response and the controller action. Practical implementation of FOPID and IOPID controllers uses the MATLAB stateflow toolbox and a NI data acquisition system. Results of the robustness analysis show that the FOPID controller has a better performance and robust stability against the experiment factors.

关键词： Factorial experimental design fractional-order PID controller robustness analysis SIMC PID controller

A realistic topological p-n junction at the Bi2Se3 （0001） surface based on planar twin boundary defects

在线全文

学校读者我要写书评

暂无评论

Nano Research 2017年第5期10卷 1784-1793页

作者： Hugo Aramberri M. Carmen Munoz Jorge I. Cerda Instituto de Ciencia de Materiales de Madrid (ICMM-csic) Cantoblanco Madrid 28049 Spain

We propose a realistic topological p-n junction （TPNJ） by matching two Bi2Se3 （0001） slabs with opposite arrangements of planar twin boundary defects. The atomistic modeling of such a device leads to dislocation defects in the hexagonal lattice in several quintuple layers. Nevertheless, total energy calculations reveal that the interface relaxes, yielding a smooth geometrical transition that preserves the nearest-neighbors fcc-type geometry throughout these defect layers. The electronic, magnetic, and transport properties of the junction have then been calculated at the ab initio level under open boundary conditions, i.e., employing a thin-film geometry that is infinite along the electron transport direction. Indeed, a p-n junction is obtained with a built-in potential as large as 350 meV. The calculations further reveal the spin texture across the interface with unprecedented detail. As the main result, we obtain non-negligible transmission probabilities around the F point, which involve an electron spin-flip process while crossing the interface.

关键词： topological insulators p-n junctions spintronics electronic devices twin boundaries

Fast preparation route to high-performances textured Sr-doped Ca_3Co_4O_9 thermoelectric materials through precursor powder modification

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Materials 2019年第3期62卷 399-406页

作者： Miguel Angel Torres Gustavo Garcia Idoia Urrutibeascoa Maria Antonieta Madre Juan Carlos Diez Andres Sotelo ICMA (csic-Universidad de Zaragoza) Centro Stirling S. Coop. Mondragon Unibertsitatea

This work presents a short and very efficient method to produce high performance textured Ca_3Co_4O_9 thermoelectric materials through initial powders modification. Microstructure has shown good grain orientation, and low porosity while slightly lower grain sizes were obtained in samples prepared from attrition milled powders. All samples show the high density of around 96% of the theoretical *** similar characteristics are reflected in, approximately,the same electrical resistivity and Seebeck coefficient values for both types of samples. However, in spite of similar power factor(PF) at low temperatures, it is slightly higher at high temperature for the attrition milled samples. On the other hand, the processing time reduction(from 38 to 2 h) when using attrition milled precursors, leads to lower mechanical properties in these samples. All these data clearly point out to the similar characteristics of both kinds of samples, with a drastic processing time decrease when using attrition milled precursors, which is of the main economic importance when considering their industrial production.

关键词： ceramics oxides hot-pressing electrical properties power factor

Towards full repair of defects in reduced graphene oxide films by two-step graphitization

在线全文

学校读者我要写书评

暂无评论

Nano Research 2013年第3期6卷 216-233页

作者： Ruben Rozada Juan I, Paredes Silvia Villar-Rodil Amelia Marlinez-Alonso Juan M. D. Tascon Instituto Nacional del Carbon INCAR-CSIC Apartado 73 33080 Oviedo Spain

The complete restoration of a perfect carbon lattice has been a central issue in the research on graphene derived from graphite oxide since this preparation route was first proposed several years ago, but such a goal has so far remained elusive. Here, we demonstrate that the highly defective structure of reduced graphene oxide sheets assembled into free-standing, paper-like films can be fully repaired by means of high temperature annealing （graphitization）. Characterization of the films by X-ray photoelectron and Raman spectroscopy, X-ray diffraction and scanning tunneling microscopy indicated that the main stages in the transformation of the films were （i） complete removal of oxygen functional groups and generation of atomic vacancies （up to 1,500 ~C）, and （ii） vacancy annihilation and coalescence of adjacent overlapping sheets to yield continuous polycrystalline layers （1,800-2,700 ~C） similar to those of highly oriented graphites. The prevailing type of defect in the polycrystalline layers were the grain boundaries separating neighboring domains, which were typically a few hundred nanometers in lateral size, exhibited long-range graphitic order and were virtually free of even atomic-sized defects. The electrical conductivity of the annealed films was as high as 577,000 S-m-1, which is by far the largest value reported to date for any material derived from graphene oxide, and strategies for further improvement without the need to resort to higher annealing temperatures are suggested. Overall, this work opens the prospect of truly achieving a complete restoration of the carbon lattice in graphene oxide materials.

关键词： graphene graphene oxide films annealing defect

Glial regenerative response in the imaginal discs of Drosophila melanogaster

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2023年第1期18卷 109-110页

作者： Sergio B.Velarde Antonio Baonza Centro de Biología Molecular“Severo Ochoa” CSIC/UAMMadridSpain

Glial cells play a key role during nervous system development and actively participate in all the cellular processes involved in maintaining its structural robustness and functional *** response to neuronal damage,glial cells proliferate,migrate to the injured region and change their morphology,function,and behavior(Gallo and Deneen,2014;Kato et al.,2018).This glial regenerative response is associated with the repairing function of these cells and is found across species,suggesting that it may reflect a common underlying genetic mechanism(Kato et al.,2018).

关键词： damage migrate