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finite element analysis and experimental validation of polymer-metal contacts in block-on-ring configuration

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friction 2024年第3期12卷 554-568页

作者： K.Y.Eayal AWWAD Khosro fALLAHNEZHAD B.f.YOUSIf Ahmad MOSTAfA Omar ALAJARMEH A.SHALWAN Xuesen ZENG Mechanical Engineering Department Faculty of EngineeringTafila Technical UniversityTafila 66110Jordan Medical Device Research Institute College of Science and EngineeringFlinders UniversitySouth Australia 5042Australia Centre for future Materials University of Southern QueenslandToowoomba 4350Australia Department of Manufacturing Engineering Technology Public Authority for Applied Education and TrainingKuwait 13092Kuwait

The wear profile analysis,obtained by different tribometers,is essential to characterise the wear ***,most of the available methods did not take the stress distribution over the wear profile in consideration,which causes inaccurate *** this study,the wear profile of polymer–metal contact,obtained by block-on-ring configuration under dry sliding conditions,was analysed using finite element modelling(fEM)and experimental ***’s wear equation was integrated into a developed fORTRAN-UMESHMOTION code linked with Abaqus software.A varying wear coefficient(k)values covering both running-in and steady state regions,and a range of applied loads involving both mild and severe wear regions were measured and implemented in the *** fEM was in good agreement with the *** model reproduced the stress distribution profiles under variable testing conditions,while their values were affected by the sliding direction and maximum wear depth(hmax).The largest area of the wear profile,exposed to the average contact stresses,is defined as the normal *** the critical zones were characterized by high stress concentrations reaching up to 10 times of that at the normal *** wear profile was mapped to identify the critical zone where the stress concentration is the key point in this *** surface features were examined in different regions using scanning electron microscope(SEM).Ultimately,SEM analysis showed severer damage features in the critical zone than that in the normal zone as proven by ***,the literature data presented and considered the wear features the same at any point of the wear *** this study,the normal zone was determined at a stress value of about 0.5 MPa,whereas the critical zone was at about 5.5 *** wear behaviour of these two zones showed totally different features from one another.

关键词： polymer-to-metal contact block-on-ring wear profile wear model

雷公藤甲素前药脂质体纳米递送系统的构建及抗胰腺癌活性评价

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中国药学杂志 2024年第10期59卷 911-920页

作者：刘梦梦陈行钱洁成冯兰妮魏如婷陈建明武鑫福建中医药大学福州350122 上海维洱实验室上海201712

目的制备雷公藤甲素木蜡酸酯脂质体(triptolide lignoceric acid ester liposome,TPL-LA-lip),对其进行表征,并考察其对胰腺癌的治疗效果。方法首先采用薄膜水合法制备TPL-LA-lip,以单因素试验与Box-Behnken响应面法对处方工艺进行优化... 详细信息

目的制备雷公藤甲素木蜡酸酯脂质体(triptolide lignoceric acid ester liposome,TPL-LA-lip),对其进行表征,并考察其对胰腺癌的治疗效果。方法首先采用薄膜水合法制备TPL-LA-lip,以单因素试验与Box-Behnken响应面法对处方工艺进行优化筛选;其次对脂质体的形态、粒径分布、Zeta电位及初步稳定性进行表征,并评价其在体外介质中的释放行为;最后采用鼠源胰腺癌细胞(Panc 02)荷瘤小鼠模型,评价TPL-LA-lip的体内抗胰腺癌活性。结果制备出的TPL-LA-lip呈类球形,粒径分布均一,初步稳定性良好。平均粒径为(105.60±0.01)nm,Zeta电位为(-34.54±0.17)mV,包封率为(98.30±0.32)%,载药量为(8.33±0.24)%。在含有30%乙醇的磷酸盐缓冲液(PBS)介质中,24 h时前药脂质体的体外累积释放度为40.35%,显示出明显的缓释作用。第15天药效学实验结束时,阴性对照、空白脂质体、雷公藤甲素(triptolide,TP)溶液、Minnelide溶液和TPL-LA-lip各组的小鼠肿瘤体积分别为(849.45±53.72)(880.45±121.45)(602.09±56.80)(265.67±23.12)(237.67±38.30)mm3,体质量变化率分别是18.12%、21.29%、-3.62%、13.06%、和19.97%。与阴性对照、TP溶液两组相比,TPL-LA-lip组肿瘤体积具有显著统计学差异(P<0.05);此外,TPL-LA-lip组小鼠体质量及器官指数与阴性对照组无明显差异,而经TP溶液治疗后的小鼠体质量及器官指数明显降低,初步显示出TPL-LA-lip良好的生物安全性。结论高脂溶性的雷公藤甲素木蜡酸酯前药,改善了TP的制剂成药性,制成的脂质体具有较高的包封率,且稳定性良好。前药技术结合脂质体载体递送TP,可以显著增强药物的抗胰腺癌作用,降低毒副作用,为TP前药纳米给药系统的开发提供新的思路与实验基础。

关键词：雷公藤甲素脂质体 Box-Behnken响应面法胰腺癌

Specific *** valorem taxation and social welfare in mixed duopoly with foreign ownership

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Economic and Political Studies 2024年第2期12卷 207-219页

作者： Ming Sun Leonard f.S.Wang Qidi Zhang School of Economics and Management Chang’an UniversityXi’anChina Wenlan School of Business Zhongnan University of Economics and LawWuhanChina

In this paper,we set up a mixed duopoly competition model between state-owned and private firms in order to compare specific and ad valorem *** that the total output under specific and ad valorem taxation remains unchanged,we find that if the public firm is completely privatised,the output of the private firm under the two tax schemes will be the *** the public firm is not completely privatised,the output of the the private firm under specific taxation will be greater than that under ad valorem *** the private firm is a pure local one,the social benefits will be the same under the two tax ***,if the private firm is a joint venture that involves domestic and foreign entities,social welfare under ad valorem taxation will be greater than that under specific taxation.

关键词： Specific taxation ad valorem taxation mixed duopoly imperfect competition privatisation foreign ownership

Sex differences in the risk of retinopathy of prematurity:a systematic review,frequentist and Bayesian meta‑analysis,and meta‑regression

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World Journal of Pediatrics 2024年第4期20卷 340-352页

作者： Tamara M.Hundscheid Silvia Gulden Mohamad f.Almutairi františek Bartoš Giacomo Cavallaro Eduardo Villamor Division of Neonatology Department of PediatricsMosaKids Children’s HospitalMaastricht University Medical Center(MUMC+)School for Oncology and Reproduction(GROW)Maastricht UniversityP.Debyelaan 25.P.O.Box 58006202 AZ MaastrichtThe Netherlands Neonatal Intensive Care Unit Sant’Anna HospitalComoItaly Department of Psychology University of Amsterdam1001 NK AmsterdamThe Netherlands Neonatal Intensive Care Unit Fondazione IRCCS Ca’Granda Ospedale Maggiore PoliclinicoMilanItaly

Background Retinopathy of prematurity(ROP)is generally considered to be more frequent in males than in ***,it is not known whether sex differences in ROP affect all degrees of the condition,are global and have changed as neonatology has *** aimed to conduct a systematic review and meta-analysis of studies addressing sex differences in the risk of developing *** PubMed/MEDLINE and Embase databases were *** frequentist,random-effects risk ratio(RR)and 95%confidence interval(CI)were *** model averaged(BMA)meta-analysis was used to calculate the Bayes factors(Bfs).The Bf10 is the ratio of the probability of the data under the alternative hypothesis(H1)over the probability of the data under the null hypothesis(H0).Results We included 205 studies(867,252 infants).frequentist meta-analysis showed a positive association between male sex and severe ROP(113 studies,RR=1.14,95%CI=1.07–1.22)but no association with any ROP(144 studies,RR=1.00,95%CI=0.96–1.03).BMA showed extreme evidence in favor of H1 for severe ROP(Bf10=71,174)and strong evidence in favor of H0 for any ROP(Bf10=0.05).The association between male sex and severe ROP remained stable over time and was present only in cohorts from countries with a high or high-middle sociodemographic *** Our study confirms the presence of a male disadvantage in severe ROP but not in less severe forms of the *** are variations in the sex differences in ROP,depending on geographical location and sociodemographic level of the countries.

关键词： Oxidative stress Retinopathy of prematurity Sex characteristics

Dynamical study of varicella-zoster virus model in sense of Mittag-Leffler kernel

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International Journal of Biomathematics 2024年第3期17卷 153-183页

作者： Qura Tul Ain Aziz Khan Thabet Abdeljawad J.f.Gomez-Aguilar Saleem Riaz Department of Mathematics Guizhou University GuiyangGuizhou 550025P.R.China Department of Mathematics and Sciences Prince Sultan University P.O.Bor 66833 11586 RiyadhSaudi Arabia Department of Medical Research China Medical University Taichung 40402Taiwan CONACyT-Tecnologico Nacional de Mécico/CENIDET Interior Internado Palmira S/N Col.Palmira C.P.62490CuernavacaMorelosMécico IConsejo Academico Universidad Virtual CNCIMonterreyMécico School of Automation Northwestern Polytechnical University 170072 Xian P.R.China

The primary varicella-zoster virus(VzV)infection that causes chickenpox(also known as varicella),spreads quickly among people and,in severe circumstances,can cause to fever and *** this paper,the Mittag-Leffler fractional operator is used to examine the mathematical representation of the *** fractional-order differential equations are created in terms of the disease's dynamical analysis such as S:Susceptible,V:Vaccinated,E:Exposed,I:Infectious and R:*** derive the existence criterion,positive solution,Hyers-Ulam stability,and boundedness of results in order to examine the suggested fractional-order model's ***,some numerical examples for the VzV model of various fractional orders are shown with the aid of the generalized Adams-Bashforth-Moulton approach to show the viability of the obtained results.

关键词： Varicella-zoster virus model Hyers-Ulam stability ABC fractional operator Schauder fix point theory numerical analysis

Numerical Analysis of the Magnetic Dipole Effect on a Radiative ferromagnetic Liquid flowing over a Porous Stretched Sheet

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fluid Dynamics & Materials Processing 2024年第2期20卷 293-310页

作者： G.Dharmaiah f.Mebarek-Oudina K.S.Balamurugan N.Vedavathi Department of Mathematics Narasaraopeta Engineering CollegeNarasaraopetIndia Department of Physics Faculty of SciencesUniversity of 20 Août 1955-SkikdaSkikdaAlgeria Department of Mathematics RVR&JC College of EngineeringGunturIndia Department of Mathematics Koneru Lakshmaiah Education FoundationVaddeswaramIndia

The effects of a magnetic dipole on a nonlinear thermally radiative ferromagnetic liquidﬂowing over a stretched surface in the presence of Brownian motion and thermophoresis are *** means of a similarity transformation,ordinary differential equations are derived and solved afterwards using a numerical(the BVP4C)*** impact of various parameters,namely the velocity,temperature,concentration,is presented *** is shown that the nanoparticles properties,in conjunction with the magnetic dipole effect,can increase the thermal conductivity of the engineered nanoﬂuid and,consequently,the heat *** with earlier studies indicates high accuracy and effectiveness of the numerical *** increase in the Brow-nian motion parameter and thermophoresis parameter enhances the concentration and the related boundary *** skin-friction rises when the viscosity parameter is increased.A larger value of the ferromagnetic para-meter results in a higher skin-friction and,vice versa,in a smaller Nusselt number.

关键词： Brownian motion thermo-phoresis radiation magnetic dipole BVP4C non-linear

Photofermentative hydrogen production by immobilized Rhodopseudomonas sp. S16-VOGS3 cells in photobioreactors

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Energy Reviews 2024年第1期3卷 39-48页

作者： Isabela C.Moia Aikaterini Kanaropoulou Demetrios f.Ghanotakis Pietro Carlozzi Eleftherios Touloupakis Research Institute on Terrestrial Ecosystems National Research CouncilVia Madonna del Piano 1050019Sesto FiorentinoFIItaly Department of Chemistry University of CreteVoutes Campus70013 HeraklionGreece

One of the most important solutions to overcome energy and environmental problems and to replace the fossil fuel-based economy could be the use of photosynthetic *** use of photosynthetic microorganisms is a potential alternative to energy generation from fossil fuels because they efficiently produce hydrogen(H_(2)).Immobilization of photosynthetic microorganisms is used for many biotechnological applications such as H_(2) *** method appears attractive because it restricts cell movement in an entrapped *** of Rhodopseudomonas sp.S16-VOGS3 cells is a promising way to improve H_(2) *** this work,the ability of immobilized Rhodopseudomonas sp.S16-VOGS3 cells to produce H_(2) was investigated in two types of *** PBRs used in this work were a cylindrical one with 0.2 L working volume(C-PBR)and a flat Roux type with 0.6 L working volume(fRT-PBR).The calcium alginate beads prepared were resistant to culture mixing and showed little leakage of cells,and the immobilized cells continued the photofermentation process in both *** immobilized cells in the C-PBR produced 936.8 mL of H_(2) with an average H_(2) production rate of 2.99 mL/*** average productivity was 126.4μL(H_(2))/mg(cells)/h or 14.96 mL(H_(2))/L(culture)/h,and the light conversion efficiency was 2.37%.The immobilized cells in the fRT-PBR produced a total of 662.2 mL of H_(2) with an average H_(2) production rate of 1.55 mL/*** average productivity was 31.1μL(H_(2))/mg(cells)/h or 2.58 mL(H_(2))/L(culture)/h,and the light conversion efficiency was 0.52%.The more uniform and therefore more efficient degree of bacterial cell mixing achieved in the C-PBR with cylindrical configuration played an important role compared to the *** the fRT-PBR,the beads were aggregated at the bottom,which limited light penetration and resulted in low H_(2) production efficiency.

关键词： Photobioreactor Rhodopseudomonas sp.S16-VOGS3 Photofermentation Hydrogen production Calcium alginate

Optimal Design of Hybrid Microgrid in Isolated Communities of Ecuador

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 488-499页

作者： Luis A.Pesantes Ruben Hidalgo-León Johnny Rengifo Miguel Torres Jorge Aragundi JoséCordova-Garcia Luis f.Ugarte facultad de Ingeniería en Electricidad y Computación of Escuela Superior Politécnica del Litoral(ESPOL)University GuayaquilEcuador Department of Electrical Engineering at Universidad Técnica federico Santa María SantiagoChile IEEE

In rural territories, the communities use energy sources based on fossil fuels to supply themselves with electricity, which may address two main problems: greenhouse gas emissions and high fuel prices. Hence, there is an opportunity to include renewable resources in the energy mix. This paper develops an optimization model to determine the optimal sizing, the total annual investment cost in renewable generation, and other operating costs of the components of a hybrid microgrid. By running a k-means clustering algorithm on a meteorological dataset of the community under study, the hourly representative values become input parameters in the proposed optimization model. The method for the optimal design of hybrid microgrid is analyzed in six operating scenarios considering:(1) 24-hour continuous power supply;(2) load shedding percentage;(3) diesel power generator(genset) curtailment;(4) the worst meteorological conditions;(5) the use of renewable energy sources including battery energy storage systems(BESSs);and(6) the use of genset. A mathematical programming language(AMPL) tool is used to find solutions of the proposed optimization model. Results show that the total costs of microgrid in the scenarios that cover 100% of the load demand(without considering the scenario with 100% renewables) increase by over 16% compared with the scenario with genset operation limitation. for the designs with power supply restrictions, the total cost of microgrid in the scenario with load shedding is reduced by over 27% compared with that without load shedding.

关键词： Battery energy storage system(BESS) isolated community microgrid renewable energy optimization

Rescattering of stimulated Raman side scattering in nonuniform plasmas

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Matter and Radiation at Extremes 2024年第5期9卷 68-76页

作者： S.Tan Q.Wang Y.Chen W.B.Yao C.Z.Xiao J.f.Myatt School of Physics and Electronics Hunan UniversityChangsha 410082China Institute of Applied Physics and Computational Mathematics Beijing 100094China School of Electrical and Information Engineering Anhui University of Science and TechnologyHuainanAnhui 232001China Department of Electrical and Computer Engineering University of Alberta9211116 St.NWEdmontonAlberta T6G 1H9Canada

Rescattering of stimulated Raman side scattering(SRSS)is observed for the first time via two-dimensional(2D)particle-in-cell(PIC)*** construct a theoretical model for the rescattering process,which can predict the region of occurrence of mth-order SRSS and estimate its *** rescattering process is identified by the 2D PIC simulations under typical conditions of a direct-drive inertial confinement fusion *** electrons produced by second-order SRSS propagate nearly perpendicular to the density gradient and gain nearly the same energy as in first-order SRSS,but there is no cascade acceleration to produce superhot *** studies for a wide range of ignition conditions show that SRSS and associated rescatterings are robust and important processes in inertial confinement fusion.

关键词： nonuniform acceleration scattering