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Tribological behavior of lubricant-impregnated porous polyimide

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Friction 2024年第4期12卷 711-725页

作者： Jinbang LI Ningning ZHOU Janet s.s.WONG school of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Beijing Key Laboratory of Long-life Technology of precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100029China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

porous materials impregnated with lubricants can be used in conditions where limited lubricant is *** this work,three porous polyimides(ppI)with different densities were ***(pAO)impregnated ppI(ippI)discs were rubbed against steel and sapphire *** operando observations of the ippI-sapphire contacts show that oil is released under an applied load,forming a meniscus around *** at the outlet is created at high sliding *** amount of released oil increases with increasing ppI *** moduli,E*,estimated based on the actual contact size show that trapped oil in ippIs contributes to load *** higher speeds,tribological rehydration of the contact occurs in low density ippI,with that E*rises with *** high density ppIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the ppI network and possibly the rate of oil *** of ippI-steel contacts is governed by the mechanical properties of the ppI,the flow of the lubricant,and the roughness of the ppI *** low-and medium-density(highly porous,high roughness)ppIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological *** high density(low porosity)ppI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest *** results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions.

关键词： polyimide porous material friction mechanism polymer limited lubrication

A comprehensive review of genetic causes of obesity

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World Journal of pediatrics 2024年第1期20卷 26-39页

作者： Marcio Jose Concepcion-Zavaleta Juan Eduardo Quiroz-Aldave Maria del Carmen Durand-Vasquez Elman Rolando Gamarra-Osorio Juan del Carmen Valencia de la Cruz Claudia Mercedes Barrueto-Callirgos susan luciana puelles-Leon Elena de Jesus Alvarado-Leon Frans Leiva-Cabrera Francisca Elena Zavaleta-Gutierrez Luis Alberto Concepcion-Urteaga Jose paz-Ibarra Universidad Cientifica del sur Bolivar 2150 AvenuePueblo Libre15084LimaPeru Division of Medicine Hospital de Apoyo ChepénChepenPeru Division of Family Medicine Hospital de Apoyo ChepénChepenPeru Division of Endocrinology Hospital Victor Lazarte EchegarayTrujilloPeru Division of pediatrics Hospital de Apoyo ChepenChepenPeru Division of Internal Medicine Hospital de Apoyo ChepenChepenPeru Division of Genetics Universidad Nacional de TrujilloTrujilloPeru Division of Neonatology Hospital Belen de TrujilloTrujilloPeru Division of Internal Medicine Universidad Nacional de TrujilloTrujilloPeru Department of Medicine School of MedicineUniversidad Nacional Mayor de San MarcosLimaPeru

Background Obesity is a multifactorial chronic disease with a high,increasing worldwide *** causes account for 7%of the cases in children with extreme *** sources This narrative review was conducted by searching for papers published in the pubMed/MEDLINE,Embase and sciELO databases and included 161 *** search used the following search terms:"obesity","obesity and genetics","leptin","prader-Willi syndrome",and"melanocortins".The types of studies included were systematic reviews,clinical trials,prospective cohort studies,cross-sectional and prospective studies,narrative reviews,and case *** The leptin-melanocortin pathway is primarily responsible for the regulation of appetite and body ***,several important aspects of the pathophysiology of obesity remain *** causes of obesity can be grouped into syndromic,monogenic,and polygenic causes and should be assessed in children with extreme obesity before the age of 5 years,hyperphagia,or a family history of extreme obesity.A microarray study,an analysis of the melanocortin type 4 receptor gene mutations and leptin levels should be performed for this *** are three therapeutic levels:lifestyle modifications,pharmacological treatment,and bariatric *** Genetic study technologies are in constant development;however,we are still far from having a personalized approach to genetic causes of obesity.A significant proportion of the affected individuals are associated with genetic causes;however,there are still barriers to its approach,as it continues to be underdiagnosed.

关键词： Leptin Melanocortin Obesity prader-Willi syndrome precision medicine

Enhancing fatigue performance of AZ31 magnesium alloy components fabricated by cold metal transfer-based wire arc directed energy deposition through LpB

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Journal of Magnesium and Alloys 2024年第4期12卷 1638-1662页

作者： shambhu Kumar Manjhi srikanth Bontha A.s.s.Balan Department of Mechanical Engineering National Institute of Technology KarnatakaSurathkalSrinivasanagarMangaloreKarnataka 575025India

Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace ***,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing *** this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 *** findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED *** plasticity Burnishing(LpB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the *** treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress ***,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LpB specimens.A higher fraction of Low Angle Grain Boundaries(LAGBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature *** contrast,wrought and WA-DED+LpB specimens displayed a higher percentage of High Angle Grain Boundaries(HAGBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue *** findings underscore the effectiveness of LpB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy *** study highlights the importance of LpB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface d

关键词： Wire arc additive manufacturing AZ31 Mg alloy Low plasticity burnishing Low cycle fatigue test strain amplitude

Ferroelectricity Induced by Oxygen Vacancies in Rhombohedral ZrO_(2) Thin Films

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Energy & Environmental Materials 2024年第1期7卷 229-237页

作者： Veniero Lenzi José p.B.silva Břetislav Šmíd Vladimir Matoín Cosmin M.Istrate Corneliu Ghica Judith L.MacManus-Driscoll Luís Marques physics Center of Minho and porto Universities(CF-UM-Up) University of MinhoCampus de Gualtar 4710-057Braga Portugal Laboratory of physics for Materials and Emergent Technologies LapMETUniversity of Minho4710-057Braga Portugal Department of surface and plasma science Faculty of Mathematics and PhysicsCharles UniversityV Holešovičkách 218000Prague 8 Czech Republic National Institute of Materials physics 105 bis Atomistilor 077125Magurele Romania Department of Materials science and Metallurgy 27 Charles Babbage Rd.Cambridge CB3 OFSUK

Rhombohedral phase Hf_(x)Zr_(1.x)O_(2)(HZO,x from 0 to 1)films are promising for achieving robust ferroelectric polarization without the need for an initial wake-up pre-cycling,as is normally the case for the more commonly studied orthorhombic ***,a large spontaneous polarization observed in rhombohedral films is not fully understood,and there are also large discrepancies between experimental and theoretical *** this work,in rhombohedral ZrO_(2)thin films,we show that oxygen vacancies are not only a key factor for stabilizing the phase,but they are also a source of ferroelectric polarization in the *** is shown experimentally through the investigation of the structural properties,chemical composition and the ferroelectric properties of the films before and after an annealing at moderate temperature(400℃)in an oxygen environment to reduce the V_(o)concentration *** experimental work is supported by density functional theory(DFT)calculations which show that the rhombohedral phase is the most stable one in highly oxygen defective ZrO_(2)*** DFT calculations also show that V_(o)contribute to the ferroelectric *** findings reveal the importance of V_(o)for stabilizing rhombohedral ZrO_(2)thin films with superior ferroelectric properties.

关键词： charged defects ferroelectric polarization rhombohedral phase stability zirconia

Intraoperative application of three-dimensional printed guides in total hip arthroplasty: A systematic review

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World Journal of Orthopedics 2024年第7期15卷 660-667页

作者： Tim p Crone Bart M W Cornelissen Jakob Van Oldenrijk pieter Koen Bos Ewout s Veltman Department of Orthopedic surgery and sports Medicine Erasmus Medical CenterRotterdam 3015 GDNetherlands Department of Oral and Maxillofacial surgery Erasmus Medical CenterRotterdam 3015 GDNetherlands

BACKGROUND Acetabular component positioning in total hip arthroplasty(THA)is of key importance to ensure satisfactory post-operative outcomes and to minimize the risk of *** majority of acetabular components are aligned freehand,without the use of navigation *** specific instruments(psI)and three-dimensional(3D)printing of THA placement guides are increasingly used in primary THA to ensure optimal *** To summarize the literature on 3D printing in THA and how they improve acetabular component *** pubMed was used to identify and access scientific studies reporting on different 3D printing methods used in *** studies with 236 hips in 228 patients were *** studies could be divided into two main categories;3D printed models and 3D printed *** 3D printing in THA helped improve preoperative cup size planning and post-operative Harris hip scores between intervention and control groups(p=0.019,p=0.009).Otherwise,outcome measures were heterogeneous and thus difficult to *** overarching consensus between the studies is that the use of 3D guidance tools can assist in improving THA cup positioning and reduce the need for revision THA and the associated *** The implementation of 3D printing and psI for primary THA can significantly improve the positioning accuracy of the acetabular cup component and reduce the number of complications caused by malpositioning.

关键词： Total hip arthroplasty Three-dimensional printing Hip replacement surgery Three-dimensional planning surgical guides

Old-growth mixed dipterocarp forests show variable losses and gains in aboveground biomass and standing carbon over forty years

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Forest Ecosystems 2024年第1期11卷 14-23页

作者： sisira Ediriweera Champika Bandara Tithira Lakkana shanika Jayasinghe David Woodbury Arun Dayanandan B.M.p.singhakumara Xiangcheng Mi I.A.U.N.Gunatilleke C.V.s.Gunatilleke Mark sAshton Department of science and Technology Uva Wellassa UniversityBadullaSri Lanka The Forest school Yale School of the EnvironmentYale UniversityNew HavenCT06511USA Department of Forestry and Environmental science University of Sri JayewardenepuraNugegodaSri Lanka state Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing100093China Botany Department University of PeradeniyaPeradeniyaSri Lanka

Background:No studies have documented long-term trends in aboveground biomass(AGB)for mixed-dipterocarp forests(MDF),the dominant rain forest type in tropical wet equatorial *** our study,we sought to document such trends over forty years across three sites representing lowland to lower montane ***:To do this,we established fifty 100 m×25 m plots in 1978 across three sites sampled along an elevation gradient,identified as mature old-growth *** measured trees for diameter at breast height that we identified to species and *** took wood samples to calculate species wood-specific *** re-measured plots in 1998 and again in ***:We show standing AGB for all sites combined to be 517.52 Mg·ha^(-1)in 1978,but this declined by 17%over 40 years to 430.11 Mg·ha^(-1).No differences exist among sites in AGB primarily because of considerable within site variation;but interactions of time with site show declines across sites were not uniform,one remained about the *** few species represented a high proportion of the AGB with the top five species comprising between 34%and 65%,depending upon site and year *** species,Mesua nagassarium,represented a disproportionately large amount of AGB and decline over time,particularly at the low elevation ***:Our results are directly relevant to estimating AGB and standing carbon sequestered in *** study is the first to demonstrate varying but overall,declining trends in amounts of AGB among forests making predictions of biomass and standing carbon in MDF difficult over wide regions.

关键词： Western ghats shorea spp. southeast Asia sri Lanka Tropical rain forest Wood specific gravity

single atom Cu-N-C catalysts for the electro-reduction of CO_(2) to CO assessed by rotating ring-disc electrode

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Journal of Energy Chemistry 2024年第1期88卷 169-182,I0004页

作者： s.pérez-Rodríguez M.Gutiérrez-Roa C.Giménez-Rubio D.Ríos-Ruiz p.Arévalo-Cid M.V.Martínez-Huerta A.Zitolo M.J.Lázaro D.sebastián Instituto de Carboquímica(CsIC) Miguel Luesma Castán 450018 ZaragozaSpain Instituto de Catálisis y petroleoquímica(CsIC) Marie Curie 228049 MadridSpain synchrotron sOLEIL L’Orme des MerisiersDépartementale 12891190France

The electrochemical CO_(2) reduction reaction(CO_(2)RR) to controllable chemicals is considered as a promising pathway to store intermittent renewable energy. Herein, a set of catalysts based on copper-nitrogendoped carbon xerogel(Cu-N-C) are successfully developed varying the copper amount and the nature of the copper precursor, for the efficient CO_(2)RR. The electrocatalytic performance of Cu-N-C materials is assessed by a rotating ring-disc electrode(RRDE), technique still rarely explored for CO_(2)RR. For comparison, products are also characterized by online gas chromatography in a H-cell. The as-synthesized Cu-NC catalysts are found to be active and highly CO selective at low overpotentials(from -0.6 to -0.8 V ***) in 0.1 M KHCO_(3), while H_(2) from the competitive water reduction appears at larger overpotentials(-0.9 V vs. RHE). The optimum copper acetate-derived catalyst containing Cu-N_(4) moieties exhibits a CO_(2)-to-CO turnover frequency of 997 h^(-1) at -0.9 V vs. RHE with a H_(2)/CO ratio of 1.8. These results demonstrate that RRDE configuration can be used as a feasible approach for identifying electrolysis products from CO_(2)RR.

关键词： Cu-N-C Carbon xerogel Rotating ring disc electrode Carbon dioxide reduction reaction Carbon monoxide

Effects of neoadjuvant chemotherapy vs chemoradiotherapy in the treatment of esophageal adenocarcinoma:A systematic review and meta-analysis

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World Journal of Gastroenterology 2024年第11期30卷 1621-1635页

作者： Armand Csontos Alíz Fazekas Lajos szakó Nelli Farkas Csenge papp szilárd Ferenczi szabolcs Bellyei péter Hegyi András papp Department of surgery University of PécsMedical SchoolClinical CenterPécs H-7624BaranyaHungary Institute of Bioanalysis University of PécsMedical SchoolPécs H-7624BaranyaHungary Institute for Translational Medicine University of PécsMedical SchoolPécs H-7624BaranyaHungary Department of Emergency Medicine Clinical CenterUniversity of PécsMedical SchoolPécs 7624BaranyaHungary Department of Oncotherapy University of PécsMedical SchoolClinical CenterPécs H-7624BaranyaHungary Centre for Translational Medicine Semmelweis UniversityBudapest 1085Hungary Institute of pancreatic Diseases Semmelweis UniversityBudapest H-1083Hungary

BACKGROUND Neoadjuvant therapy is an essential modality for reducing the clinical stage of esophageal cancer;however,the superiority of neoadjuvant chemotherapy(nCT)or neoadjuvant chemoradiotherapy(nCRT)is ***,a discussion of these two modalities is *** To investigate the benefits and complications of neoadjuvant *** To address this concern,predefined criteria were established using the pICO *** independent authors performed comprehensive searches using predetermined *** analyses were performed to identify significant differences between *** publication bias was visualized using funnel *** quality of the data was evaluated using the Risk of Bias Tool 2(RoB2)and the GRADE *** Ten articles,including 1928 patients,were included for the *** difference was detected in pathological complete response(pCR)[ps ratio(OR):0.27;95%CI:0.16-0.46],30-d mortality(p=0.015;OR:0.4;95%CI:0.22-0.71)favoring the nCRT,and renal failure(p=0.039;OR:1.04;95%CI:0.66-1.64)favoring the *** significant differences were observed in terms of survival,local or distal recurrence,or other clinical or surgical *** result of RoB2 was moderate,and that of the GRADE approach was low or very low in almost all *** Although nCRT may have a higher pCR rate,it does not translate to greater long-term ***,nCRT is associated with higher 30-d mortality,although the specific cause for postoperative complications could not be *** the case of nCT,toxic side effects are suspected,which can reduce the quality of *** the quality of available studies,further randomized trials are required.

关键词： Neoadjuvant Chemotherapy Chemoradiotherapy Esophageal cancer Adenocarcinoma

Ren-integrable and ren-symmetric integrable systems

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Communications in Theoretical physics 2024年第3期76卷 62-69页

作者： s Y Lou school of physical science and Technology Ningbo UniversityNingbo315211China

A new type of symmetry,ren-symmetry,describing anyon physics and corresponding topological physics,is ***-symmetry is a generalization of super-symmetry which is widely applied in super-symmetric physics such as super-symmetric quantum mechanics,super-symmetric gravity,super-symmetric string theory,super-symmetric integrable systems and so *** and Grassmann numbers are,in some sense,dual conceptions,and it turns out that these conceptions coincide for the ren situation,that is,a similar conception of ren-number(R-number)is devised for *** particular,some basic results of the R-number and ren-symmetry are exposed which allow one to derive,in principle,some new types of integrable systems including ren-integrable models and ren-symmetric integrable *** examples of ren-integrable KdV-type systems and ren-symmetric KdV equations are explicitly given.

关键词： symmetries integrable systems anyon physics extended supersymmetry ren-symmetry