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Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2629-2644页

作者： Xiongyu Hu Marte gutierrez Zhiwei Yan Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu610031China University Transportation Center for Underground Transportation Infrastructure Colorado School of MinesGoldenUSA School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China

From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative *** of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary ***,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary ***,the literature does not document the suitability of different models for specific *** challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain *** aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact *** and biaxial compression tests are performed to calibrate the response of Creighton *** stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are *** was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock ***,the LPB model is unable to reproduce the post-peak *** to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain *** overestimates the volumetric dilation and residual shear *** LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure.

关键词： Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock

Predicting the coefficient of friction in a sliding contact by applying machine learning to acoustic emission data

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Friction 2024年第6期12卷 1299-1321页

作者： Robert gutierrez Tianshi FANG Robert MAINWARING Tom REDDYHOFF Tribology Group Department of Mechanical EngineeringImperial College LondonExhibition RoadLondon SW72AZUK Shell Global Solutions(US)Inc.Shell Technology Center Houston 3333 Highway 6 SouthHoustonTX 77082USA Shell International Petroleum Company Limited Shell CentreYork RoadLondon SE17NAUK

It is increasingly important to monitor sliding interfaces within machines,since this is where both energy is lost,and failures *** emission(AE)techniques offer a way to monitor contacts remotely without requiring transparent or electrically conductive ***,acoustic data from sliding contacts is notoriously complex and difficult to ***,we simultaneously measure coefficient of friction(with a conventional force transducer)and acoustic emission(with a piezoelectric sensor and high acquisition rate digitizer)produced by a steel‒steel rubbing *** data is then used to train machine learning(ML)algorithms(e.g.,Gaussian process regression(GPR)and support vector machine(SVM))to correlated acoustic emission with *** training requires the dense AE data to first be reduced in size and a range of processing techniques are assessed for this(e.g.,down-sampling,averaging,fast Fourier transforms(FFTs),histograms).Next,fresh,unseen AE data is given to the trained model and the resulting friction predictions are compared with the directly measured *** is excellent agreement between the measured and predicted friction when the GPR model is used on AE histogram data,with root mean square(RMS)errors as low as 0.03 and Pearson correlation coefficients reaching ***,predictions remain accurate despite changes in test conditions such as normal load,reciprocating frequency,and stroke *** paves the way for remote,acoustic measurements of friction in inaccessible locations within machinery to increase mechanical efficiency and avoid costly failure/needless maintenance.

关键词： acoustic emission condition monitoring friction machine learning Gaussian process regression support vector machine

Tracking the maximum power point of solar panels through direct estimation of optimum voltage with temperature

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Clean Energy 2024年第4期8卷 135-146页

作者： Mohammed El Bachir Ghribi Luis Garcia-gutierrez Zine Eddine Touhami Ternifi Zhixue Zheng Ghalem Bachir Michel Aillerie Applied Power Electronics Laboratory(LEPA) University of Science and Technology of Oran Mohamed BoudiafOranAlgeria Laboratoire Matériaux Optiques Photonique et Systèmes(LMOPS)Universitéde LorraineCentraleSupélecF-57000 MetzFrance Laboratory of Sustainable Development of the Electrical Energy(LDDEE) University of Science and Technology of Oran Mohamed BoudiafOranAlgeria

Electricity production from photovoltaic(PV)panels is maximized when the operating point is located at the maximum power point thanks to dedicated *** controllers are driven to track the maximum power by using various algorithms within distributed or centralized architectures accounting for factors such as partial irradiation and temperature *** effect of irradiance on the optimal panel voltage is weak or even negligible,while it is strong and quasi-linear-dependent on *** on this observation,this article introduces a straightforward method for tracking the maximum power of a PV panel by using an optimizer,focusing solely on its temperature response as an input *** proposed approach hinges on linearizing the relationship between panel temperature and operating *** relationship enables the estimation of the maximum power point through temperature measurement ***,after determination of the linear temperature coefficient of the voltage requiring only the knowledge of two optimal voltages at different temperatures,for example from the datasheet of the panel,the power tracking involves only one temperature sensor placed on the panel alongside a voltage sensor for *** principle,modelling,and validation post-panel ageing of the method are detailed in this ***,conducted using real experimental irradiation and temperature data,attests to the effectiveness of the *** indicate an average effectiveness of the method of>99.1%in tracking the maximum power,with the panel generating 2.33 kWh out of a possible 2.35 *** performance is comparable to that of tracking devices employing more complex *** simplicity and efficiency of the method make it a promising option for maximizing the power production at low cost from PV systems in small or residential,on-or off-grid connected applications.

关键词： photovoltaic maximum power point tracking hysteresis efficiency

Alzheimer’s visual variant: a report of a diagnosis easily missed on ophthalmic examination

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International Journal of Ophthalmology(English edition) 2024年第8期17卷 1571-1575页

作者： Jorge Cárdenas-Belaunzarán Lorena Wheelock-gutierrez Karen A.Cerrillo-Avila Department of Neuro-Ophthalmology Association to Prevent Blindness in MexicoI.A.P.Mexico City 04030Mexico Independent Researcher Mexico City 04040Mexico

Dear Editor,We present a case of posterior cortical atrophy(PCA),which is a syndromic entity caused by different neurodegenerative diseases,mainly Alzheimer’s disease,but it has been described in several other *** frequency is reported to be as high as 5%of all cases;however,it remains widely under-recognized among ophthalmologists and optometrists due to scarce reports in visual health-related journals[1].

关键词： diagnosis Alzheimer diseases

Changes in Adipose Tissue and Circulating Concentrations of Persistent Organic Pollutants in Midlife Women

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Environment & Health 2024年第4期2卷 243-252页

作者： Amelia Grant-Alfieri Amila Devasurendra Stuart Batterman Carrie Karvonen-gutierrez Sung Kyun Park Department of Environmental Health Sciences University of Michigan School of Public HealthAnn ArborMichigan 48109United States Department of Epidemiology University of Michigan School of Public HealthAnn ArborMichigan 48109United States

Polychlorinated biphenyls(PCBs)and organochlorine pesticides(OCPs)are persistent organic pollutants(POPs)that bioaccumulate in adipose *** investigated the relationship between change in central adiposity and changes in circulating concentrations of POPs over a 12-year period during the *** concentrations of 34 PCBs and 19 OCPs were measured at four time points(1999/2000,2002/03,2005/06,2009/11)in a cohort of midlife women,the Study of Women’s Health Across the *** mixed models were used to test the association between a change in waist circumference and a change in serum POP ***-five women contributed 181 PCB ***-nine women contributed 151 OCP *** adjustment for covariates(study site,race and ethnicity,age at baseline,parity),a one-inch(2.54 cm)increase in the change in waist circumference between visits was associated with a 4.9%decrease in the change in serum concentration of PCB 194(95%CI:−8.0%,−1.6%).No associations were observed for other PCB congeners or the presence of *** increase in the difference in waist circumference over time was not associated with a change in the difference in serum concentrations of PCBs and OCPs except for PCB 194,possibly due to the high lipophilicity.

关键词： persistent organic pollutants PCBs pesticides adipose tissue women midlife

Discovering genetic biomarkers for targeted cancer therapeutics with eXplainable Artificial Intelligence

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Cancer Communications 2024年第5期44卷 584-588页

作者： Debaditya Chakraborty Elizabeth gutierrez-Chakraborty Cristian Rodriguez-Aguayo Hakan Başağaoğlu Gabriel Lopez-Berestein Paola Amero School of Civil and Environmental Engineering and Construction Management The University of Texas at San AntonioSan AntonioTexasUSA Department of Cell Systems and Anatomy University of Texas Health Science CenterSan AntonioTexasUSA Department of Experimental Therapeutics The University of Texas MD Anderson Cancer CenterHoustonTexasUSA Edwards Aquifer Authority San AntonioTexasUSA

High-Grade Serous Ovarian Cancer(HGSC)is the most prevalent and lethal form of gynecologic malignancies[1],accounting for 70%-80%of ovarian cancer *** decades of research,the overall survival rate for HGSC has remained largely unchanged[2],and patients with advanced stages of the disease have only a 41%chance of surviving beyond five years[3].

关键词： cancer Cancer targeted

Hydrogeochemical and isotopic assessment of the origin of NO_(3)^(−)and N-NH_(3)contents in the aquifer located in a closed lacustrine volcano-sedimentary basin in the metropolitan area of Mexico City

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Acta Geochimica 2024年第4期43卷 719-736页

作者： Jose Ivan Morales-Arredondo Maria Aurora Armienta Hernandez Joel Edmundo Ortega-gutierrez Elisa Cuellar Ramirez Natural Resources Department Institute of GeophysicsNational Autonomous University of MexicoCiudad Universitaria No.3000Col.Copilco UniversidadCoyoacán Delegation04360 MexicoCDMXMexico Instituto Politecnico Nacional ***án 55La Laguna Ticoman07340 MexicoCDMXMexico Benemérita Universidad Autónoma de Puebla Ciudad Universitaria Col.San ManuelPueblaPueMexico

To explain the presence and spatial distribution of NO_(3)^(−)and N-NH_(3)in the Aquifer of the Metropolitan Area of Mexico City(AMAMC),a hydrogeochemical and isotopic analysis using^(13)C DIC(as well as the stable isotopes^(18)O and^(2)H)in groundwater was *** aquifer is located in an old closed lacustrine volcano-sedimentary basin;some wells hosted in the semi-confined zone contain high N-NH_(3)concentrations,while others present NO_(3)^(−)contents in the recharge zones(hosted in an oxidizing environment).In this study,a change in the isotopic signature(primarily in^(18)O and^(2)H)was observed from the recharge zones to the basin center in some of the wells with high NO_(3)^(−)concentrations,this behavior can be attributed to evaporation during the incorporation of recently infiltrated *** addition,the results for^(13)C(along with ^(2) H)in wells with the highest N-NH_(3)concentrations exhibited an atypically broad range of *** indicated the occurrence of hydrogeochemical and/or biochemical processes in the aquifer(in an oxidizing or reducing environment),such as organic degradation,bacterial decomposition(primarily in the ancient Lake Texcoco and which acts as a natural sink for carbon,nitrogen,sulfur,and phosphorus),besides rock weathering and dissolution,which may be responsible for a very marked isotopic modification of the^(13)C(and,to a lesser extent,2 H).Methanotrophic bacterial activity and methanogenic activity may be related to N-NH_(3)removal processes by oxidation and residual water incorporation respectively,whereas the increase in the NO_(3)^(−)content in some wells is due to the recent contribution of poor-quality water due to contamination.

关键词： 18 O and^(13)C isotopes Iron Hydrogeochemical processes Nitrate Nitrogen species

Histopathological impact of SARS-CoV-2 on the liver:Cellular damage and long-term complications

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World Journal of Gastroenterology 2024年第22期30卷 2866-2880页

作者： Alfonso Rodriguez-Espada Moises Salgado-de la Mora Briana Mariette Rodriguez-Paniagua Nathaly Limonde la Rosa Monica Itzel Martinez-gutierrez Santiago Pastrana-Brandes Nalu Navarro-Alvarez Department of Molecular Biology Universidad Panamericana School of MedicineCampus MéxicoMexico 03920Mexico Department of Internal Medicine Instituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico 14080Mexico Department of Surgery University of Colorado Anschutz Medical CampusDenverCO 80045United States PECEM Facultad de MedicinaUniversidad Nacional Autónoma de MéxicoMexico 04360Mexico Department of Gastroenterology Instituto Nacional de Ciencias Médicas y Nutrición Salvador ZubiránMexico 14080Mexico

Coronavirus disease 2019(COVID-19),caused by the highly pathogenic severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),primarily impacts the respiratory tract and can lead to severe outcomes such as acute respiratory distress syndrome,multiple organ failure,and *** extensive studies on the pathogenicity of SARS-CoV-2,its impact on the hepatobiliary system remains *** liver injury is commonly indicated by reduced albumin and elevated bilirubin and transaminase levels,the exact source of this damage is not fully *** mechanisms for injury include direct cytotoxicity,collateral damage from inflammation,drug-induced liver injury,and ischemia/***,evidence often relies on blood tests with liver enzyme *** this comprehensive review,we focused solely on the different histopathological manifestations of liver injury in COVID-19 patients,drawing from liver biopsies,complete autopsies,and in vitro liver *** present evidence of the direct impact of SARS-CoV-2 on the liver,substantiated by in vitro observations of viral entry mechanisms and the actual presence of viral particles in liver samples resulting in a variety of cellular changes,including mitochondrial swelling,endoplasmic reticulum dilatation,and hepatocyte *** ly,we describe the diverse liver pathology observed during COVID-19 infection,encompassing necrosis,steatosis,cholestasis,and lobular *** also discuss the emergence of long-term complications,notably COVID-19-related secondary sclerosing *** the histopathological liver changes occurring during COVID-19 infection is pivotal for improving patient recovery and guiding decision-making.

关键词： Liver SARS-CoV-2 COVID-19 Angiotensin-converting enzyme 2 Histopathology Liver biopsies Liver autopsy In vitro

Uremic Bleeding in 2 Patients with Dieulafoy’s Lesion: Case Report and Literature Review

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Open Journal of Gastroenterology 2024年第5期14卷 167-173页

作者： Gustavo Adolfo Hernández Valdez Diana Estefanía Ibarra García Juan Antonio Contreras Escamilla Janette Alejandra Gamiño gutierrez Francisco Manuel Tonatiuh Carrillo Beltran Ulises Solis Gomez Jocelyn Nataly Quintero Meléndez Ivan alejandro Medina Jimenez Marco Antonio González Villar Jorge Rojas Morales Department of Internal Medicine ISSSTE APP General Hospital of Tepic Tepic Nayarit Mexico Hospital Civil de Guadalajara Fray Antonio Alcalde Guadalajara Jalisco M&#233xico

Dieulafoy’s lesions are rare vascular malformations of the gastrointestinal tract. A Dieulafoy’s lesion is an aberrant vessel that does not reduce in caliber when it extends from the submucosa to the mucosa. Damage to this artery can cause severe and intermittent arterial bleeding from small vascular stumps that are difficult to visualize. Furthermore, these catastrophic bleeding episodes frequently result in hemodynamic instability and the need for transfusion of multiple blood products. Recently, uremic syndrome has been identified as a risk factor for gastric mucosal lesions. We present two clinical cases of acute digestive bleeding due to Dielafoy lesion with chronic kidney disease as the main cause, where two different therapies were performed endoscopically. We concluded with the results of our patients that the best therapy was the application of the hemostatic hemoclip on the injury vs the injection with adrenaline on the wound site. Uremia is identified as a risk factor for upper gastrointestinal bleeding in patients with pre-existing Dieulafoy’s lesion, as well as a higher incidence of new bleeding.

关键词： Dieulafoy’s Lesion Gastrointestinal Bleeding Endoscopy Endoscopy Hemostatic Clips Kidney Disease Adrenaline Thermal Coagulation Dieulafoy