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High-resolution patterns of palaeoenvironmental changes during the Little Ice Age and the Medieval Climate Anomaly in the northwestern Iberian Peninsula

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Geoscience Frontiers 2020年第5期11卷 1461-1475页

作者： Daniel Castro Martin Souto Maria Isabel Fraga Eduardo Garcia-Rodeja sebastian perez-diaz Jose Antonio Lopez Saez Xabier Pontevedra-Pombal Dpto.Botanica Fac.BioloxiaUniversidade de Santiago de CompostelaGaliciaSpain Dpto.Edafoloxia e Quimica Agricola Fac.BioloxiaUniversidade de Santiago de CompostelaGaliciaSpain Dpto.Geografia Urbanismo y Ordenacion Del TerritorioETS CaminosCanales y PuertosUniversidad de CantabriaSpain GI Arqueobiologia Instituto de HistoriaCCHS–CSICMadridSpain

to identify plant macrofossils,estimate peat humification and calculate hydroclimatic indices based on current bog species,with the overall aim of determining the climate conditions associated with evolution of the bog during the Medieval Climate Anomaly and the Little Ice *** proxies,together with historical and climate data,proved to be good indicators of the changes in bog surface ***:of the core led to identification of 9 different periods:two corresponding to the so-called Medieval Climate Anomaly(930 to 1345 AD,1075–665 calibrated years before present[*** BP]);four corresponding to the Little Ice Age(1345 to 1905 AD;665–105 cal yr BP);and three corresponding to the last century(1905 to 2000 AD).The findings revealed a generally dry climate that lasted until the 14th century,followed by a transition to a long period with a more humid,but characteristically very variable climate,which ended at the beginning of the 20th century and was followed by a rapid transition to more humid conditions and finally,a change to drier *** Medieval Climate Anomaly was indicated by the abundance of dry-adapted mosses(Leucobryum glaucum,Hypnum cupressiforme)and characterized by warm dry conditions and high levels of peat humification,with alternating wet *** LIA period was dated by a large abundance of Sphagnum species(an indicator of wetness)and a gradual increase in the humification ***,four different climate phases were differentiated in this ***-resolution reconstruction of the evolution of the CVM bog and the multiproxy approach have together enabled a more detailed identification of climatic variations in this area,which are generally consistent with the global models,as well as better definition of the elusive climatic oscillations in the last millennium and confirmation of the importance of local modulation of global *** study provides new information and a detailed chronology of climatic events that will hel

关键词： Last millennium Raised bog Plant macrofossil Humification analysis Southwest Europe Climate change

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Description of a Propulsion Unit Used in Guiding a Walking Machine by Recognizing a Three-point Bordered Path

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Chinese Journal of Mechanical Engineering 2016年第6期29卷 1157-1166页

作者： NUNEZ-ALTAMIRANO Diego A JUAREZ-CAMPOS Ignacio MARQUEZ-perez Lucia FLORES-diaz Ociel School of Mechanical Engineering Universidad Michoacana de San Nicolas de Hidalgo Morelia Michoacan Mexico

A reconfigurable propulsion unit based on the Peaucellier-Lipkin mechanism has the ability to describe exact straight or curved paths depending on the selected ratio between the lengths of two of its links. The Peaucellier-Lipkin mechanism with one degree of freedom is transformed into a more sophisticated parallel kinematic chain by including four more degrees of freedom. The resulting propulsion unit is able to adapt its kinematic structure and reach instant centers of rotation, in accordance with the presence of three points that border a geometric path. A laser sensor mounted on the body of the machine detects each point. Once the machine has detected the exact location of the border of the road, it walks along a curve parallel to that border. Although the proposed research describes only one propulsion unit or leg, the methodology can be applied to all the legs of the walking machine. The novel 5-DOF leg is able to reach different centers of rotation, providing either the concave or convex arcs that satisfy the basic principle of displacement of walking machines.

关键词： Propulsion unit Peaucellier-Lipkin walking machine straight line mechanism.

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A Survey of the Representations of Rational Ruled Surfaces

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Journal of Systems Science & Complexity 2021年第6期34卷 2357-2377页

作者： YUAN Chun-Ming perez-diaz Sonia SHEN Li-Yong KLMM Academy of Mathematics and Systems SciencesChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Grupo ASYNACS Dpto.de Fisica y MatematicasUniversidad de Alcala28871-Alcala de HenaresMadridSpain

The rational ruled surface is a typical modeling surface in computer aided geometric design.A rational ruled surface may have different representations with respective advantages and *** this paper,the authors revisit the representations of ruled surfaces including the parametric form,algebraic form,homogenous form and Plucker ***,the transformations between these representations are proposed such as parametrization for an algebraic form,implicitization for a parametric form,proper reparametrization of an improper one and standardized reparametrization for a general *** on these transformation algorithms,one can give a complete interchange graph for the different representations of a rational ruled *** rational surfaces given in algebraic form or parametric form not in the standard form of ruled surfaces,the characterization methods are recalled to identify the ruled surfaces from them.

关键词： Birational transformation characterization implicitization parametrization rational ruled surface reparametrization

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A technical and socioeconomic approach to estimate forest residues as a feedstock for bioenergy in northern Mexico

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Forest Ecosystems 2019年第4期6卷 312-322页

作者： Guadalupe Carrasco-diaz Gustavo perez-Verdin Jonathan Escobar-Flores Marco Antonio Marquez-Linares Instituto Politecnico Nacional CIIDIR Dgo.

Background: Forest residues can be a feasible alternative for converting energy into fuels, electricity, or *** to other second-generation bioenergy sources, they do not compete for food, are relatively cheap,abundant in forest-rich areas, and more importantly their energy balance is close to zero. Biomass estimations can help design energy strategies to reduce fossil fuels dependency. Because of the land property distribution in Mexico,biomass estimations should consider not only the physical availability, but also the willingness of landowners to extract such raw ***: This study presents a methodological approach for evaluating the potential use of forest residues as a feedstock to generate bioenergy in northern Mexico. Remote sensing and field forest inventory were used to estimate the quantity and distribution of forest residues. In addition, a discrete choice analysis evaluated landowners’ preferences towards bioenergy development, including the most important factors that influence their willingness to extract their products and the expected *** and conclusions: Considering both physical and socio-economic aspects, results showed that about59,000 metric tons per year could be available in the study area. The vast majority of landowners surveyed are willing to extract forest residues, as long as they are presented with extraction plans with the highest income. However, many showed concerns about the environmental impacts this activity can have on soils,plants, and fauna. These results can help evaluate the potential of these resources for bioenergy development.

关键词： Bioenergy Choice experiments Forest landowners Forest residues Remote sensing

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Controlled building of CdSe@ZnS/Au and CdSe@ZnS/ Au2S/Au nanohybrids

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Nano Research 2015年第7期8卷 2271-2287页

作者： Raquel E. Galian Pilar diaz Antonio Ribera Alejandro Rincon-Bertolin Said Agouram Julia perez-Prieto Instituto de Ciencia Molecular (ICMol) Universidad de Valencia c/ Catedrdtico Jose Beltran 2 46980 Paterna Valencia Spain Department of Applied Physics and Electromagnetism Dr. Moliner 50 Universidad de Valencia 461 00 Burjassot Valencia Spain

The addition of Au3. to spherical amine-capped CdSe@ZnS nanoparticles in toluene at room temperature and under darkness can lead to ternary CdSe@ZnS/Au nanohybrids. We demonstrate that this happens only when the nanoparticles possess a relatively thin ZnS shell, thus showing that thickness plays a key role in gold deposition on the CdSe@ZnS nanoparticle surface. Our hypothesis is that the amine ligand acts as the reductant of Au3＋ ions into Au＋ ions, whose affinity for sulfur would keep them at the CdSe@ZnS surface. This interaction stabilizes the Au＋ ion, making it less prone to reduction than a non-coordinated Au＋ ion. In CdSe@ZnS with a thin shell, Au＋ ions at the surface of, or most probably within, the ZnS shell cause the transfer of Cd2＋ ions into the solution. Subsequently, the core Se2- anion, which is a better reductant than the shell S2- reduces Au＋ ions to Au（0）, and large gold nanoparticles （AuNPs） are quickly deposited on the CdSe@ZnS surface in room temperature process, leading to ternary CdSe@ZnS/Au nanohybrids. In solution, these ternary nanohybrids progressively transform into quaternary CdSe@ZnS/Au2S/Au nanohybrids due to the reaction of the shell S2- anion with the remaining Au＋ at the CdSe@ZnS surface, thus leading to the growth of Au2S nanoparticles on the CdSe@ZnS surface while Zn concomitantly leaches from the nanohybrid into the solution. Photoirradiation of the heterostructures with visible light enhances their emission efficiency. Comparatively, irradiation of the precursors, i.e., CdSe@ZnS nanoparticles, causes a drastic decrease in their emission accompanied by a blue shift of their emission maximum. The optical properties of these nanohybrids were analyzed by absorption and fluorescence （steady-state and time-resolved） spectroscopy, and the composition of the samples and the chemical states were determined by energy dispersive X-ray spectroscopy （EDX） and X-ray photoelectron spectroscopy （XPS）, respectively. Finally, the structural and m

关键词： heterostructures semiconductor nanoparticle metallic fluorescence time-resolved studies

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A novel and stretchable carbon-nanotube/Ni@TiO_(2):W photocatalytic composite for the complete removal of diclofenac drug from the drinking water

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Journal of Environmental Sciences 2023年第4期126卷 575-589页

作者： Ernesto Valadez-Renteria Rafael perez-Gonzalez Christian Gomez-Solis Luis Armando diaz-Torres Armando Encinas Jorge Oliva Vicente Rodriguez-Gonzalez Consejo Nacional de Ciencia y Tecnología-División de Materiales Avanzados Instituto Potosino de Investigación Científica y TecnológicaSan Luis Potosí78216México División de Ciencias e Ingenierías Universidad de GuanajuatoLeón 37150México Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados(GEMANA) Centro de Investigaciones enópticaA.C.Lomas Del CampestreLeón 37150México

We present the structural,morphological and photocatalytic properties of stretchable composites made with carbon nanotubes (CNTs),silicon rubber and Ni@TiO_(2):W nanoparticles(TiWNi NPs) with average size of 37±2 *** images showed that the TiWNi NPs decorated the surface of the CNT fibers,which are oriented in a preferential *** NPs presented a mixture of anatase/rutile phases with cubic *** performance of the TiWNi powders and stretchable composites was evaluated for the photocatalytic degradation of diclofenac (DCF) anti-inflammatory drug under ultraviolet-visible *** results revealed that the maximum DCF degradation percentages were 34.6%,91.9%,97.1%,98.5%and 100%for the CNT composite (stretched at 0%),TiWNi powders,CNT+TiWNi(stretched at 0%),CNT+TiWNi (stretched at 50%) and CNT+TiWNi (stretched at 100%),***,stretching the CNT+TiWNi composites was a good strategy to enhance the DCF degradation percentage from 97.1%to 100%,since stretching created additional defects (oxygen vacancies) that acted as electron sink,delaying the electron-hole recombination,and favors the DCF ***/absorbance measurements confirmed the presence of such ***,the reactive oxygen species (ROS) were determined by the scavenger’s experiments and found that the main ROS were the·OH and O_(2)-radicals,which attacked the DCF molecules,causing their *** results of this investigation confirmed that the stretchable CNT/TiWNi-based composites are a viable alternative to remove pharmaceutical contaminants from water and can be manually separated from the decontaminated water,which is unviable using photocatalytic powders.

关键词： Diclofenac Pharmaceutical contaminant TiO_(2) Carbon nanotubes Stretchable composite Photocatalysis

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FedIDS:a federated cloud storage architecture and satellite image delivery service for building dependable geospatial platforms

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International Journal of Digital Earth 2018年第7期11卷 730-751页

作者： J.L.Gonzalez-Compean Victor J.Sosa-Sosa Arturo diaz-perez Jesus Carretero Ricardo Marcelin-Jimenez Cinvestav-Tamulipas Ciudad VictoriaMexico ARCOS Research Group University Carlos IIIMadridSpain UAM Iztapalapa CDMX and associated to InfotecMexico

Earth observation satellites produce large amounts of images/data that not only must be processed and preserved in reliable geospatial platforms but also efficiently disseminated among partners/researchers for creating derivative products through collaborative *** can face up this challenge in a cost-effective manner by using cloud ***,outages and violations of integrity/confidentiality associated to this technology could *** article presents FedIDS,a suite of cloud-based components for building dependable geospatial *** Fed component enables organizations to build shared geospatial data infrastructure through federation of independent cloud resources to withstand outages,whereas IDS avoids violations of integrity/confidentiality of images/data in sharing information and collaboration workflows.A FedIDS prototype,deployed in Spain and Mexico,was evaluated through a study case based on a satellite imagery captured by a Mexican antenna and another based on a satellite imagery of a European observation *** acquisition,storage and sharing of images among users of the federation,the exchange of images between Mexican and Spanish sites and outage scenarios were *** evaluation revealed the feasibility,reliability and efficiency of FedIDS,in comparison with available solutions,in terms of performance,storage consume and integrity/confidentiality when sharing images/data in collaborative scenarios.

关键词： Satellite imagery Earth observation archives spatial data infrastructure collaborative workflows security reliability

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Infuence of elemental composition in environmental impacts of steel

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Journal of Iron and Steel Research International 2020年第5期27卷 598-607页

作者： E.Batuecas C.Mayo R.diaz F.J.perez Thermal and Fluid Engineering Department Carlos III University of Madrid28911 LeganesMadridSpain Chemical and Materials Engineering Department Complutense University of Madrid28040 MadridSpain Technical Sciences and Engineering UDIMA University28400 Collado VillalbaMadridSpain。

The environmental behavior of four steels was *** the operation phase of concentrating solar power plants,steels withstand high temperature because of its contact with molten ***,choosing the steel type for the molten salt tanks remains a great *** the cold tank,carbon steel is usually used although an approach with low chromium content steel is being studied for these ***,in high temperature applications,such as hot store tank,austenitic stainless steel is the most frequent ***,ferritic steel is being considered as a promising material in these *** many researchers studied the steel technical properties without considering their environmental damages,this work aimed to introduce the environmental aspects into the material choice by using the life cycle assessment *** one hand,the results showed the environmental adequacy of carbon steel against low chromium content *** the other hand,the results obtained in those steels suitable in high temperature application revealed signifcant environmental benefts from the ferritic steel instead of the austenitic steel.

关键词： Renewable energy Concentrating solar power Life cycle assessment Molten salt Ferritic steel Austenitic steel

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Interpenetrated Magnesium-Tricalcium Phosphate Composite:Manufacture,Characterization and In Vitro Degradation Test

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Acta Metallurgica Sinica(English Letters) 2017年第4期30卷 319-325页

作者： Mariano Casas-Luna Serhii Tkachenko Miroslava Horynova Lenka Klakurkova Pavel Gejdos sebastian diaz-de-la-Torre Ladislav Celko Jozef Kaiser Edgar B. Montufar CEITEC-Central European Institute of Technology Brno University of TechnologyPurkyfnova 656/123612 00 BmoCzech Republic CIITEC-Centro de Investigacion e Innovacion Tecnologica Instituto Politocnico NacionalCerrada de CECATI02250 Mexico CityMexico

Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium- tricalcium phosphate （Mg-TCP） composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration （CAMI） technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 μm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg-TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test.

关键词： Calcium phosphate Magnesium Liquid metal infiltration Spark plasma sintering Corrosion

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Preoperative pancreatic resection score:a preliminary prospective validation from Spain

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Hepatobiliary & Pancreatic Diseases International 2016年第6期15卷 667-668页

作者： Mario Rodriguez-Lopez Martin Bailon-Cuadrado Francisco J Tejero-Pintor Baltasar perez-Saborido Enrique Asensio-diaz Asterio Barrera-Rebollo General and Digestive Surgery Department Rio Hortega University HospitalDulzaina 247012ValladolidSpain

To the Editor：We read with outstanding interest the article by Celik et al. It is the first external description of the Hamburg＇s preoperative pancreatic resection （PREPARE） score since it was published in 2014 by Uzunoglu et al. According to the latter authors, it is necessary to stratify risk of major morbidity and mortality before performing a pancreatic resection, and PREPARE score is a simple index, validated in a multicenter cohort of patients undergoing this group of technically demanding procedures.

关键词： Preoperative pancreatic resection score

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