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Acoustic emission characterization of microcracking in laboratory-scale hydraulic fracturing tests

Journal of Rock Mechanics and Geotechnical engineering 2018年第5期10卷 805-817页

作者： Jesse Hampton Marte Gutierrez luis Matzar Dandan Hu Luke Frash Department of Civil & environmental engineering Colorado School of Mines Golden CO 80401 USA New england Research Inc. White River Junction VT 03766 USA Halliburton Houston TX 77032 USA Los Alamos National Laboratory Los Alamos NM 87545 USA

Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （Ae） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the Aes from several piezoelectric transducers. In-depth post-processing of the Ae event data was performed for the purpose of under- standing the individual source mechanisms. several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack Ae analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded Ae signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.

关键词： Acoustic emission (Ae) Microcracking Hydraulic fracturing Laboratory-scale testing Moment tensor analysis Fracture coalescence Computed tomography (CT) imaging

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Intruder familiarity and not duet similarity influences the territory defense in a year-round territorial bird species

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Avian Research 2022年第2期13卷 152-158页

作者： Tihana Hamzaj Brendan Graham Katherine Bonilla Ignacio Gutiérrez luis sandoval Institute of evolutionary ecology and Conservation Genomics University of UlmUlm Gemany Laboratorio de ecología Urbana y Comunicación Animal Escuela de BiologíaUniversidad de Costa RicaMontes de Oca CP11501-2060 Costa Rica Department of Biological sciences University of Lethbridge4401 University Dr WLethbridgeABTIK 3M4anada

To avoid unnecessary energy expenditures in territorial defense,many species(e.g.,insects,amphibians,birds,and mammals)have developed the capability to distinguish between different intruder types using visual,acoustic,and/or chemical *** the mechanism used for intruder recognition is key to understanding the dynamics of territorial *** birds that use vocalizations for territorial defense,the frequency and duration of vocalizations or the familiarity with the intruder may be the main mechanism used for intruder ***,we conducted a playback experiment with territorial White-eared Ground-sparrows(Melozone leucotis),to analyze if territorial pairs recognize intruders using frequency and duration characteristics(a bird’s response is based on how structurally similar the intruders’duets are to their own)or by familiarity with the intruders(neighbors ***-neighbors).We focused on duets because this species uses duets exclusively for territorial *** broadcasted a duet from a territorial neighbor,two duets from non-neighbors(with different frequency and duration characteristics),and a duet from a control species in 39 territorial pair from three *** playback we measured five behavioral responses:latency of the first vocalization,latency of the approach to the speaker,time spent close the speaker(within 5 m),number of individuals that approached the speaker,and the number of *** found that territorial White-eared Ground-sparrow pairs responded stronger to neighbors than non-neighbors,and this response is not influenced by duet duration or frequency *** result suggests that neighbors represent a greater territorial threat for White-eared Ground-sparrows than *** work is necessary to understand how common this observation is for tropical species that defend small territories year-round.

关键词： Dear enemy Duets Neighbor-stranger discrimination Territory defense White-eared ground-sparrows

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Oxygen vacancies engineering by coordinating oxygen-buffering CeO_(2) with CoO_(x) nanorods as efficient bifunctional oxygen electrode electrocatalyst

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Journal of energy Chemistry 2021年第8期30卷 615-625,I0013页

作者： Haihong Zhong luis Alberto estudillo-Wong Yuan Gao Yongjun Feng Nicolas Alonso-Vante state Key Laboratory of Chemical Resource engineering Beijing Engineering Center for Hierarchical CatalystsCollege of ChemistryBeijing University of Chemical TechnologyNo.15 Beisanhuan East Road100029 BeijingChina IC2MP UMR-CNRS 7285University of PoitiersF-86022 Poitiers CedexFrance Departamento de sociedad y Política Ambiental CIIEMADInstituto Politécnico NacionalCalle 30 de junio de 1520Alcaldía GAMC.P.07340 CDMXMexico Anqing Research Institute Beijing University of Chemical TechnologyNo.8 Huanhu West RoadHigh-Tech DistrictAnqing 24600China

CeO_(2)decorated CoOx rod-like hybrid,supported onto holey reduced graphene(CoOx/CeO_(2)/RGO)composite,was fabricated via a surfactant-assisted *** corresponding electrocatalytic performance towards oxygen reduction/evolution reactions(ORR and OeR)was systematically investigated in alkaline ***,morphological and compositional studies revealed changes in electronic and surface properties when CeO_(2)was introduced as an oxygen buffer *** oxygen vacancies effectively enhanced the electrocatalytic activity,while the synergistic effect of co-catalyst CeO_(2),CoOx activecenters,and defective graphene with many voids facilitate the charge/mass transfer,making CoOx/CeO_(2)/RGO an efficient and stable bifunctional electrocatalyst for OeR/ORR with△e=0.76 V(△e=e10mAcm.-2OeR-e_(1/2).ORR).This parameter is 70 mV and 270 mV lower than CoOx/RGO and the benchmark Pt/C,*** addition,the OeR/ORR bifunctionality of CoOx/CeO_(2)/RGO composite outperforms that of Pt/C catalyst in a H2-O_(2)micro fuel cell platform.

关键词： Co3O4 CeO_(2) Oxygen vacancies ORR OeR

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effects of medium-and long-distance running on cardiac damage markers in amateur runners:a systematic review,meta-analysis,and metaregression

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Journal of sport and Health science 2021年第2期10卷 192-200页

作者： Jacobo A.Rubio-Arias luis Andreu luis Manuel Martinez-Aranda Alejandro Martinez-Rodriguez Pedro Manonelles Domingo J.Ramos-Campo Faculty of sport Catholic University of San Antonio(UCAM)Murcia 30107Spain LFe Research Group Department of Health and Human PerformanceFaculty of Physical Activity and Sport Science-INEFUniversidad Politecnica de MadridMadrid 28040Spain International Chair of sports Medicine Catholic University of San Antonio(UCAM)Murcia 30107Spain Neuroscience of Human Movement Research Group(Neuromove) Catholic University of San Antonio(UCAM)Murcia 30107Spain Faculty of sciences University of AlicanteAlicante 03690Spain

Background:To finish an endurance race,athletes perform a vigorous effort that induces the release of cardiac damage *** are several factors that can affect the total number of these markers,so the aim of this review was to analyze the effect of endurance running races on cardiac damage markers and to identify the factors that modify the levels of segregation of these cardiac damage ***:A systematic search of PubMed,Web of science,and the Cochrane Library databases was *** analysis included studies where the acute effects of running races on cardiac damage markers(troponin I and troponin T)were analyzed,assessing the levels of these markers before and after the ***:The effects of running races on troponin I(mean difference=0.0381 ng/mL)and troponin T(mean difference=0.0256 ng/mL)levels were *** ages(R^(2)=14.4%,p=0.033)and body mass indexes(R^(2)=14.5%,p=0.045)of the athletes had a significant interaction with troponin *** addition,gender,mean speed,time to finish the race,and type of race can affect the level of cardiac damage ***:endurance running races induce the release of cardiac-damage markers that remain elevated for at least 24 h after the *** addition,young male athletes with high body mass indexes who perform races combining long duration and moderate intensity(i.e.,marathons)release the highest levels of cardiac damage *** should take into consideration these results in the diagnosis and treatment of patients admitted to the hospital days after finishing endurance running races.

关键词： endurance races Troponin I Troponin T Ultra-endurance

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Climate change and infectious disease: a review of evidence and research trends

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Infectious Diseases of Poverty 2023年第3期12卷 89-89页

作者： Paige Van de Vuurst luis e.escobar Virginia Tech Graduate school Translational BiologyMedicineand Health ProgramBlacksburgVAUSA Department of Fish and Wildlife Conservation Virginia TechBlacksburgVAUSA Center for emerging Zoonotic and Arthropod-Borne Pathogens Virginia TechBlacksburgVAUSA Global Change Center Virginia TechBlacksburgVAUSA Facultad de Ciencias Agropecuarias Universidad de La SalleBogotáColombia

Background Climate change presents an imminent threat to almost all biological systems across the *** recent years there have been a series of studies showing how changes in climate can impact infectious disease *** of these publications focus on simulations based on in silico data,shadowing empirical research based on feld and laboratory data.A synthesis work of empirical climate change and infectious disease research is still *** We conducted a systemic review of research from 2015 to 2020 period on climate change and infectious diseases to identify major trends and current gaps of *** was sourced from Web of science and PubMed literary repositories using a key word search,and was reviewed using a delineated inclusion criteria by a team of *** Our review revealed that both taxonomic and geographic biases are present in climate and infectious disease research,specifcally with regard to types of disease transmission and localities *** investigations on vector-borne diseases associated with mosquitoes comprised the majority of research on the climate change and infectious disease ***,demographic trends in the institutions and individuals published revealed research bias towards research conducted across temperate,high-income *** also identifed key trends in funding sources for most resent literature and a discrepancy in the gender identities of publishing authors which may refect current systemic inequities in the scientifc *** Future research lines on climate change and infectious diseases should considered diseases of direct transmission(non-vector-borne)and more research efort in the *** of local research in low-and middle-income countries was generally *** on climate change and infectious disease has failed to be socially inclusive,geographically balanced,and broad in terms of the disease systems studied,limiting our cap

关键词： Climate change Infectious disease Research trend systematic review

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Comparative carbon emission assessments of recycled and natural aggregate concrete: environmental influence of cement content

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Geoscience Frontiers 2021年第6期12卷 66-75页

作者： Marian sabǎu Dan V.Bompa luis F.O.silva Department of Civil and environmental engineering Universidad de la Costa080020 BarranquillaColombia Department of Civil and environmental engineering University of SurreyGuildford GU27XHUK Departamento de Ingeniería Civil y Arquitectura Universidad de LimaAvenida Javier Prado Este 4600Santiago de Surco 1503Peru

This work examines the environmental and geochemical impact of recycled aggregate concrete production with properties representative for structural *** environmental influence of cement content,aggregate production,transportation,and waste landfilling is analysed by undertaking a life cycle assessment and considering a life cycle inventory largely specific for the *** obtain a detailed insight into the optimum life cycle parameters,a sensitivity study is carried out in which supplementary cementitious materials,different values of natural-to-recycled aggregate content ratio and case-specific transportation distances were *** results show that carbon emissions were between 323 and 332 kgCO_(2)e per cubic metre of cement only natural aggregate *** values can be reduced by up to 17%by replacing 25%of the cement with fly *** contrast,carbon emissions can increase when natural coarse aggregates are replaced by recycled aggregates in proportions of 50%and 100%,and transportation is not included in ***,the concrete with 50%recycled aggregate presented lower increase,only 0.3%and 3.4%for normal and high strength concrete,*** some cases,the relative contribution of transportation to the total carbon emissions increased when cement was replaced by fly ash in proportions of 25%,and case-specific transportation distances were *** absolute values,the concrete mixes with 100%recycled aggregates and 25%fly ash had lower carbon emissions than concrete with cement and natural aggregates *** environmental benefits can be obtained when the transportation distances of fly ash are relatively short(15–25 km)and the cement replacement by fly ash is equal or higher than 25%,considering that the mechanical properties are adequate for practical *** observations from this paper show that recycled aggregate concrete with strength characteristics representative for structural members can have lowe

关键词： Life cycle assessment Recycled aggregate Natural aggregate Transportation distance OpenLCA

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Rietveld refinement and optical properties of srWO_4:eu^(3+) powders prepared by the non-hydrolytic sol-gel method

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Journal of Rare earths 2015年第2期33卷 113-128页

作者： P.F.s.Pereira I.C.Nogueira e.Longo e.J.Nassar I.L.V.Rosa L.s.Cavalcante Chemistry Institute University of the State of Sao Paulo Julio de Mesquita Filho-UNESP Francisco DegniAraraquara-SP 14800-900 Brazil LIeC-Chemistry Department Federal University of Sao Carlos Via Washington Luis Km 235Sao Carlos-SP 13565-905 Brazil University of Franca-UNIFRAN Via Dr.Armando Sales de OliveiraNo.201 Franca-SP 14404-600 Brazil CCN-DQ-GeRATeC University of the State of Piauí Joao Cabral 2231 P.O.Box 391Terezina PI 64002-150 Brazil

We investigated the effect of annealing time on the structure and optical properties of sr WO4：eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 *** and differential thermal analyses revealed that sr WO4：eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and Rietveld refinement data confirmed that all powders had a scheelite-type tetragonal ***-Raman and Fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]*** properties were investigated by ultraviolet-visible（UV-vis）diffuse reflectance,and photoluminescence（PL）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of sr WO4：eu^3＋ *** properties validated that the eu^3＋ electric-dipole（^5D0→^7F2）transition in PL emission spectra was dominant which proved that eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7F2）/（^5D0→^7F1）]band ratios showed that eu^3＋ ions were located in a low symmetry *** PL emission,ηandτproved the dependence on the annealing time in the behavior of sr WO4：eu3＋powders with a higher relative emission PL intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h.

关键词： srWO4 Rietveld refinement optical band gap eu^(3+) +-rare earth luminescence

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Revealing the complexity of vampire bat rabies "spillover transmission"

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Infectious Diseases of Poverty 2023年第1期12卷 102-110页

作者： luis e.escobar Andres Velasco-Villa Panayampalli s.satheshkumar Yoshinori Nakazawa Paige Van de Vuurst Department of Fish and Wildlife Conservation Virginia TechBlacksburgVAUSA Virginia Tech Graduate school Translational BiologyMedicineand Health ProgramBlacksburgVAUSA Global Change Center Virginia TechBlacksburgVAUSA Center for emerging Zoonotic and Arthropod‑Borne Pathogens Virginia TechBlacksburgVAUSA Facultad de Ciencias Agropecuarias Universidad de La SalleBogotáColombia Poxvirus and Rabies Branch Centers for Disease Control and Prevention1600 Clifton Rd.NEAtlantaGA 30333USA

Background The term virus'spillover’embodies a highly complex phenomenon and is often used to refer to viral transmission from a primary reservoir host to a new,naïve yet susceptible and permissive host *** transmission can result in a virus becoming pathogenic,causing disease and death to the new host if successful infection and transmission takes *** text The scientific literature across diverse disciplines has used the terms virus spillover,spillover transmission,cross-species transmission,and host shift almost indistinctly to imply the complex process of establishment of a virus from an original host(source/donor)to a naïve host(recipient),which have close or distant taxonomic or evolutionary *** transmission may result in unsuccessful onward transmission,if the virus dies off before ***,successful viral establishment in the new host can occur if subsequent secondary transmission among individuals of the same novel species and among other sympatric susceptible species *** such,virus spillover transmission is a common yet highly complex phenomenon that encompasses multiple subtle stages that can be deconstructed to be studied separately to better understand the drivers of disease *** virus(RABV)is a well-documented viral pathogen which still inflicts heavy impact on humans,companion animals,wildlife,and livestock throughout Latin America due substantial spatial temporal and ecological—natural and expansional—overlap with several virus reservoir ***,the rabies disease system represents a robust avenue through which the drivers and uncertainties surrounding spillover transmission can be unravel at its different subtle stages to better understand how they may be affected by coarse,medium,and fine scale *** The continued study of viral spillover transmission necessitates the elucidation of its complexities to better assess the cross-scale impacts of ecological force

关键词： Bat-borne diseases Rabies spillover Transmission

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song divergence indicates an unclear relationship between the Neotropical and Nearctic Horned Larks

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Avian Research 2021年第2期12卷 161-172页

作者： Jimmy Alexander Vargas-Puentes luis Alejandro Arias-sosa Carolina Ramos-Montaño Grupo ecología de Organismos(GeO-UPTC) Escuela de Ciencias BiológicasUniversidad Pedagógica Y Tecnológica de ColombiaTunjaColombia

Background:some studies have indicated that the Horned Larks(eremophila alpestris)should be considered as a species *** it split into four species or clades and seven subclades based on genetic,morphological,and biogeographic ***,other aspects like song divergence have not been studied and several subspe-cies have not been evaluated,leading to important information gaps in this group of *** this work,we aimed to assess the differences in song traits and playback response between the Nearctic subclade and the Neotropical or Colombian subspecies ***:We compared six song traits between these groups and performed field playback experiments,to test the response of the Neotropical larks to both *** tested the difference in the variables for separate as well as by principal component analysis(PCA).Results:We found significant differences(pe individual song traits and the PCA analysis between the two ***,the PCA analysis showed a clearer divergence of the Neotropical songs in comparison to the Nearctic songs of different locations within North ***,the playback analysis showed a significantly lower response of *** to the songs of the Nearctic ***:Besides this song divergence,there are important ecological and biogeographic differences between the Neotropical and Nearctic Horned Larks,that indicate an unclear relationship between these two ***,further morphological and genetic studies are required to clarify the taxonomy of the Neotropical Horned Lark and define if they share the same evolutionary history as the other subspecies of the Nearctic subclade.

关键词： Birdsong eremophila alpestris peregrina song features speciation Reproductive barrier

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Factors Influencing spanish Brands' Cross-border e-commerce in China

Factors Influencing Spanish Brands' Cross-border E-commerce ...

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作者： luis sanz Figueras 上海交通大学

学位级别：硕士

The pandemic has accelerated the widespread adoption of cross-border e-commerce,and the shift in Chinese consumer behaviors towards buying imported goods *** limitation of mobility and travel abroad caused by the virus,together with the growing development of technologies and high online connectivity,have boosted interest in buying foreign products *** border e-commerce(CBeC)is a new concept derived from *** is defined as an online transaction of buying and selling products and services using information communication technologies(ICTs),where buyers and sellers are in two different countries and therefore,different jurisdictions(Mou,Ren,et al.2019).selling CBeC products in China has many advantages for the foreign company,such as preferential tax policies or import's license exemption,but at the same time,implies a good mastering of the most important factors that drive its *** study explores the critical factors associated with the success or failure of the purchasing process in the context of CBeC in *** purpose is to provide a better understanding of CBeC and to delve into the fundamental factors that determine spanish companies' ability to succeed when selling their products in China through *** reviewing the most pertinent literature regarding the relevant macro and micro factors that explore conducting business through CBeC,this master's thesis proposes a theoretical model of six factors,that finds its origin in the Hazarika and Mousavi(2022)and Gorostidi-Martinez et al.(2017)*** six factors that influence Cross-Border e-Commerce success and are included in the theoretical model are:“Cultural values and population demographics";"Communication aspects";"Monetary cost of purchase";"CBeC platform and products";"Policy and Control Mechanisms"and " Product-Country Image".To determine which of these factors affect the success or failure of spanish companies implementing CBeC in China,a 28-item construct was dr

关键词： Cross-border e-Commerce export Online shopping spain China B2B B2C CBeC marketplace

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