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Non-adhesive and adhesive contacts of an elastic quarter-or eighth-space with freely sliding sides

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Friction 2024年第9期12卷 2052-2063页

作者： Qiang LI valentin L.POPOV Technische Universität Berlin Berlin 10623Germany

The contact of an elastic quarter-or eighth-space is studied under the condition that the movement of the side surface of the quarter-space is constrained:It can slide freely along the plane of the side surface but its normal movement is blocked(for example,by a rigid wall).The solution of this contact problem can be easily achieved by additionally applying a mirrored load to an elastic ***-adhesive contact and the Johnson–Kendall–Roberts(JKR)-type adhesive contact between a rigid sphere and an elastic quarter-space under such a boundary condition is numerically simulated using the fast Fourier transform(FFT)-assisted boundary element method(BEm).Contacts of an elastic eighth-space are investigated using the same *** on the position of the sphere relative to the side edge,different contact behavior is *** the case of adhesive contact,the force of adhesion first increases with increasing the distance from the edge of the quarter-space,achieves a maximum,and decreases further to the JKR-value in large distance from the *** enhancement of the force of adhesion compared to the half-space-contact is associated with the pinning of the contact area at the *** provide the maps of the force of adhesion and their analytical approximations,as well as pressure distributions in the contact plane and inside the quarter-/eighth-space.

关键词： quarter-space eighth-space adhesion edge effect boundary element method(BEm)

Approximate contact solutions for non-axisymmetric homogeneous and power-law graded elastic bodies:A practical tool for design engineers and tribologists

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Friction 2024年第2期12卷 340-355页

作者： valentin L.POPOV Qiang LI Emanuel WILLERT Institute of mechanics Technische Universität BerlinBerlin 10623Germany

In two recent papers,approximate solutions for compact non-axisymmetric contact problems of homogeneous and power-law graded elastic bodies have been suggested,which provide explicit analytical relations for the force–approach relation,the size and the shape of the contact area,as well as for the pressure distribution *** solutions were derived for profiles,which only slightly deviate from the axisymmetric *** the present paper,they undergo an extensive testing and validation by comparison of solutions with a great variety of profile shapes with numerical solutions obtained by the fast Fourier transform(FFT)-assisted boundary element method(BEm).Examples are given with quite significant deviations from axial symmetry and show surprisingly good agreement with numerical solutions.

关键词： normal contact non-axisymmetric indenter extremal principle generalized method of dimensionality reduction(mDR) functional elastic grading

A cross-sectional analysis of the effectiveness of a nutritional support programme for people with tuberculosis in Southern madagascar using secondary data from a non-governmental organisation

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Infectious Diseases of Poverty 2024年第1期13卷 101-102页

作者： mara Anna Franke Julius valentin Emmrich Fierenantsoa Ranjaharinony Onja GbrilleRavololohanitra Harizaka Emmanuel Andriamasy Samuel Knauss Nadine muller Global Digital Health Lab at Charité Center for Global Health Charité – Universitätsmedizin Berlin Berlin Germany London School of Hygiene and Tropical medicine London UK Ärzte Für madagaskar E.V. Leipzig Germany Heidelberg Institute of Global Health Heidelberg University Heidelberg Germany Berlin Institute of Health at Charité - Universitätsmedizin Berlin Berlin Germany Doctors for madagascar Antananarivo Madagascar Speciality Network: Infectious Diseases and Respiratory medicine Charité - Universitätsmedizin Berlin Berlin Germany

Background There is a strong,bi-directional link between tuberculosis(TB)and undernutrition:TB often causes undernutrition,and undernourished people are more likely to contract TB and experience worse ***,several TB nutritional support programmes exist;however,evidence on their effectiveness is limited and *** study evaluates the effect of a nutritional support programme implemented for people with TB in the Atsimo-Andrefana region,madagascar in *** this programme,undernourished people with TB[with a body mass index(BmI)ofm]receive 0.6 L of vegetable oil and 6.0 kg of a soy-wheat blend per month throughout their TB *** We analysed secondary non-governmental organisation data collected between January and Novem-ber 2022 in the Atsimo-Andrefana region,Southern madagascar,including information on an individual's medical conditions(e.g.,type of TB,treatment outcomes)and nutritional status measured prior to,during,and after comple-tion of treatment(e.g.,height,weight,mid-upper arm circumference).We conducted descriptive analyses of patient baseline characteristics and outcomes to assess the impact of the provided nutritional support on the BmI of people With *** A total of 1310 people with TB were included in the study[9.9%(130)children under the age of 5,32.1%(420)children between 5 and 18 years,58.0%(760)adults].55.4% of children under 5,28.1% of children between ages 5 and 18,and 81.3%of adults were undernourished at treatment initiation.42.3%(55/130)of children under 5 experi-enced severe acute malnutrition at treatment *** the average Bml of adults with TB receiving food support increased over time,from 17.1 kg/m^(2)(interquartile range:15.8-18.3,range:10.3-22.5)to 17.9 kg/m^(2)(interquartile range:16.6-19.1,range:11.9-24.1),most adults remained undernourished even after completing TB *** The current TB nutritional support programme falls short of sufficiently increasing the Bm

关键词： Tuberculosis Sub-Saharan Africa Undernutrition Nutritional support

Green synthesis of luminescent La-mOF nanoparticle from waste poly(ethylene terephthalate) for high-performance in Fe(Ⅲ) detection

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Rare metals 2024年第8期43卷 3833-3843页

作者： Zhi Gong Zhi-Kui Dai Zhi-Yue Dong Qiu-Xuan Liu valentin A.milichko Hua-Jian Liu Jie Liu Ran Niu Jiang Gong Key Laboratory of material Chemistry for Energy Conversion and Storage Hubei Key Laboratory of Material Chemistry and Service FailureHubei Engineering Research Center for Biomaterials and Medical Protective MaterialsSemiconductor Chemistry CenterSchool of Chemistry and Chemical EngineeringMinistry of EducationHuazhong University of Science and TechnologyWuhan 430074China School of Chemical Engineering and Pharmacy Wuhan Institute of TechnologyWuhan 430073China Collaborative Innovation Center for Advanced Organic Chemical materials Co-constructed by the Province and ministry Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules and College of Chemistry and Chemical EngineeringHubei UniversityWuhan 430062China School of Physics and Engineering ITMO UniversitySt.Petersburg197101Russia School of materials Science and Engineering Hubei UniversityWuhan430062China Guangdong Provincial Key Laboratory of Technique and Equipment for macromolecular Advanced manufacturing School of Mechanical and Automotive EngineeringKey Laboratory of Polymer Processing EngineeringMinistry of EducationSouth China University of TechnologyGuangzhou 510641China

Developing luminescent metal-organic frameworks(mOFs) capable of high-efficiency Fe^(3+)sensing has aroused great attraction in the fields of biology,chemistry,***,previous solvothermal methods are limited by organic solvent usage,time consuming,high pressure,and high-energy ***,we propose the waste-tomOF strategy towards the scale-up production of La-mOF nanoparticles through the ball milling of recycled poly(-ethylene terephthalate)(PET) bottles and La(NO_(3))_(3)·_(6)H_(2)*** goes on alkaline hydrolysis to form 1,4-benzenedicarboxylic acid sodium salt(Na_(2)BDC) and ethylene glycol by ball ***,BDC reacts with La^(3+)to form *** as-prepared La-mOF crystal nanoparticles possess a rod-like morphology with the size of few hundred ***,La-mOF nanoparticles display high selectivity and sensitivity for Fe^(3+)*** quenching constant and limit of detection are 5.29×10^(3)(mol·L^(-1))^(-1) and 0.147 μmol·L^(-1),respectively,thus surpassing many advanced Fe^(3+) *** to the result of density functional theory,the high Fe^(3+) detection performance of La-mOF is related to the complexing of Fe^(3+)with La-mOF,which leads to the gradual dissociation of the coordination bond between terephthalic acid and La^(3+).It is anticipated that the mechanochemistry milling-based wasteto-mOF strategy provides a new platform for the massive production of functional mOFs in a green manner.

关键词： metal-organic framework Waste polyester mechanochemistry milling Fluorescence sensor

High-frequency lacustrine sequence stratigraphy of clastic lakes: lessons from ancient successions

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Journal of Palaeogeography 2024年第4期13卷 621-645页

作者： Carlos Zavala Hua-Qing Liu Xiang-Bo Li valentin Trobbiani Yang Li mariano Arcuri Agustin Zorzano Departamento de Geología Universidad Nacional del Sur (UNS) GCS Consulting Services.Bahía Blanca Research Institute of Petroleum Exploration&Development-Northwest Consejo Nacional de Investigaciones Científicas y T ecnicas (CONICET) Shandong University of Science and Technology

Sequence stratigraphic concepts and methods provide novel tools for performing stratigraphic analysis, allowing us to improve our understanding of depositional models and basin evolution. main controls and depositional elements(e.g., surfaces, systems tracts, parasequences, etc.) recognized in conventional sequence stratigraphy are designed for marine-related systems. In contrast, the sequence stratigraphy of lacustrine successions is much more complex and poorly understood, because it is not driven by sea-level changes, but by a complex interaction between tectonics and high-frequency climatic cycles. The comprehensive analysis of the water balance of lacustrine systems allows the recognition of three types of lake conditions: Underfilled, balanced-fill and overfilled lakes. Understanding the lake conditions in ancient successions is fundamental for unraveling lacustrine sequence stratigraphy, since these conditions effectively control water salinity, internal stacking pattern and the characteristics of systems tracts. Underfilled lakes are hydrologically closed lakes, and consequently, the lake-level can highly fluctuate, driven by high-frequency wet-dry climatic cycles. During wet periods, rivers supply water and sediments, resulting in fining-and thinning-upward elementary depositional sequences(EDS's) accumulated during the transgressive systems tract(TST). In contrast, dry periods are characterized by a relative lake-level fall with the subaerial exposure of lake margin areas during the regressive systems tract(RST). Lake water salinity can fluctuate from brackish to hypersaline. Balanced-fill lakes are partially closed lakes, and consequently, they have characteristics of both underfilled and overfilled lakes. During the TST, the lake is in underfilled condition, and consequently, the introduction of water and sediment will accumulate a fining-upward interval until reaching the spill point during the maximum flooding. The RST is accumulated under an overfille

关键词： Lacustrine sequence stratigraphy Underfilled lakes Balanced-fill lakes Overfilled lakes Forced transgression Forced regression

Zeolites for the environment

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Green Carbon 2024年第1期2卷 12-32页

作者： Qiaolin Lang Peng Lu Xiaobo Yang valentin Valtchev The Zeomat Group Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesLaoshan DistrictQingdao CN-266101China Normandie University ENSICAENUNICAENCNRSLaboratoire Catalyse et SpectrochimieCaen F-14000France

Zeolites are characterized by their microporous,crystalline structures with a four-connected framework with variable compositions,predominantly *** are extensively utilized as adsorbents,catalysts,and ion exchangers across domestic and industrial *** the ongoing energy transition from fossil fuels to renewable sources and the pursuit of environmentally sustainable development,zeolites are increasingly being explored beyond their traditional application *** are investigated for their adsorption and catalytic capabilities in the protection and restoration of air,water,and soil quality,as well as in the environmentally friendly“green”production of *** review article details these novel and potential applications of zeolites,emphasizing the unique properties that render them suitable for each specific use case and discussing how these properties can be fine-tuned through material selection or tailored synthesis methods.

关键词： Zeolite Environment Sorption Catalysis Air,water and soil protection Green production of chemicals

Direct amplification of femtosecond optical vortices in a single-crystal fiber

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Photonics Research 2024年第1期12卷 27-32页

作者： CHANGSHENG ZHENG TIANYI DU LEI ZHU ZHANXIN WANG KANGZHEN TIAN YONGGUANG ZHAO ZHIYONG YANG HAOHAI YU valentin PETROV Jiangsu Key Laboratory of Advanced Laser materials and Devices School of Physics and Electronic EngineeringJiangsu Normal UniversityXuzhou 221116China State Key Laboratory of Crystal materials and Institute of Crystal materials Shandong UniversityJinan 250100China max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy 12489 BerlinGermany

Spatially twisted light with femtosecond temporal structure is of particular interest in strong-field physics and light–matter ***,present femtosecond vortex sources exhibit limited power handling capabilities,and their amplification remains an ongoing challenge particularly for high-order orbital angular momentum(OAm)states due to several inherent technical ***,we exploit a straightforward approach to directly amplify a femtosecond optical vortex(FOV,OAm=-8?)by using a two-stage single-crystal fiber(SCF)amplifier system without pulse stretching and compression in the time domain,delivering 23-W,163-fs pulses at a repetition rate of1 *** spatial and temporal features are well-conserved during the amplification,as well as the high modal purity(>96%).The results indicate that the multi-stage SCF amplifier system is particularly suited for direct amplification of high-order *** generated high-power femtosecond OAm laser beams are expected to help reveal complex physical phenomena in light–matter interactions and pave the way for practical applications in attoscience,laser plasma acceleration,and high-dimension micromachining.

关键词： fiber amplifier crystal

Cholera Recurrence within Benin Littoral County: Analysis of Epidemics from 2008, 2016 to 2023

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Open Journal of Epidemiology 2024年第2期14卷 353-365页

作者： mongbo Virginie Avahoun valentin Agbomakouzo Evariste Sopoh Ghislain Aguemon Badirou Ouendo Edgard-marius Regional Institute of Public Health ministry of Public health of Benin Cotonou B&#233ninBenin Faculty of Health Sciences University of Abomey-Calavi Abomey-Calavi Benin

Introduction: Cholera is an acute diarrheal infection caused by the bacillus Vibrio cholerae, which can be fatal in a few hours if left untreated. It rages in endemic-epidemic mode in several countries, including Benin. Despite being the economic capital, the largest city in Benin and the most urbanized municipality in the country, the Littoral County, confounded with the city of Cotonou, is subject to recurrent epidemics. This paper aims to analyze successive cholera epidemics with a view of highlighting the factors contributing to this recurrence. methods: A secondary analysis was done of the cholera-related databases of the County health office from 2016 to 2023, and its Situation Report No. 79 of December 7th, 2016, to describe the 2016 epidemic. Database data were analyzed in Excel. Results: Similarly to 2008, the 2016 cholera epidemic in Cotonou, which recorded 519 cases and 07 deaths, i.e. a case-fatality rate of 1.35%, spread to the town and six neighboring municipalities. The municipality of So-Ava, home to the index case, had the highest overall attack rate. The two epidemics share the same period of severity. Both epidemic and endemic cases are concentrated in the first seven boroughs of Cotonou, located on the lagoon shore, with low levels of hygiene and sanitation and a poor supply of drinking water. Conclusion: Low levels of hygiene, sanitation and drinking water supply all play a part in the recurrence of cholera epidemics. Sanitation work. Undertaken by the Beninese government is a ray of hope for improving this situation. meanwhile, public awareness of hygiene measures must continue.

关键词： Recurrence Cholera Cotonou

Exploring fs-laser irradiation damage subthreshold behavior of dielectric mirrors via electrical measurements

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High Power Laser Science and Engineering 2024年第2期12卷 24-32页

作者： Petrisor Gabriel Bleotu Radu Udrea Alice Dumitru Olivier Uteza maria-Diana mihai Dan Gh matei Daniel Ursescu Stefan Irimiciuc valentin Craciun Extreme Light Infrastructure-Nuclear Physics(ELI-NP) Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering(IFIN-HH)MagureleRomania Doctoral School of Physics University of BucharestMagureleRomania LULI-CNRS CEAUniversite SorbonneEcole PolytechniqueInstitut Polytechnique de ParisPalaiseau CEDEXFrance Apel Laser IlfovRomania Aix-marseille University CNRSLP3 UMR 7341MarseilleFrance Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering(IFIN-HH) MagureleRomania University Politehnica of Bucharest BucharestRomania National Institute for Lasers Plasma and Radiation Physics MagureleRomania

With ultrafast laser systems reaching presently 10 PW peak power or operating at high repetition rates,research towards ensuring the long-term,trouble-free performance of all laser-exposed optical components is *** work is focused on providing insight into the optical material behavior at fluences below the standardized laser-induced damage threshold(LIDT)value by implementing a simultaneous dual analysis of surface emitted particles using a Langmuir probe(LP)and the target current(TC).HfO_(2) and ZrO_(2) thin films deposited on fused silica substrates by pulsed laser deposition at various O_(2) pressures for defect and stoichiometry control were irradiated by Gaussian,ultrashort laser pulses(800 nm,10 Hz,70 fs)in a wide range of *** TC and LP collected signals were in good agreement with the existing theoretical description of laser–matter interaction at an ultrashort time *** approach for an in situ LIDT monitoring system provides measurable signals for below-threshold irradiation conditions that indicate the endurance limit of the optical surfaces in the single-shot energy scanning *** LIDT value extracted from the LP-TC system is in line with the multipulse statistical analysis done with ISO 21254-2:2011(E).The implementation of the LP and TC as on-shot diagnostic tools for optical components will have a significant impact on the reliability of next-generation ultrafast and high-power laser systems.

关键词： HfO_(2) in situ detection Langmuir probe laser-induced damage threshold target current ZrO_(2)