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Effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on tensile and bending properties of high-Al-containing Mg alloys

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journal of Magnesium and Alloys 2024年第2期12卷 779-793页

作者： Sumi jo Gyo Myeong Lee jong Un Lee Young Min Kim Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Magnesium Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on the uniaxial tensile and three-point bending properties of extruded Mg alloys containing high Al *** extruded Mg–9Al–1Zn–0.3Mn(AZ91)alloy contains lamellar-structured Mg_(17)Al_(12)discontinuous precipitates along the grain boundaries,which are formed via static precipitation during natural air *** extruded Mg–11Al–1Zn–0.3Mn(AZ111)alloy contains spherical Mg_(17)Al_(12)precipitates at the grain boundaries and inside the grains,which are formed via dynamic precipitation during *** to inhomogeneous distribution of precipitates,the AZ111 alloy consists of two different precipitate regions:precipitate-rich region with numerous precipitates and finer grains and precipitate-scarce region with a few precipitates and coarser *** AZ111 alloy exhibits a higher tensile strength than the AZ91 alloy because its smaller grain size and more abundant precipitates result in stronger grain-boundary hardening and precipitation hardening effects,***,the tensile elongation of the AZ111 alloy is lower than that of the AZ91 alloy because the weak cohesion between the dynamic precipitates and the matrix facilitates the crack initiation and *** bending,a macrocrack initiates on the outer surface of bending specimen in both *** AZ111 alloy exhibits higher bending yield strength and lower failure bending strain than the AZ91 *** bending specimens of the AZ91 alloy have similar bending formability,whereas those of the AZ111 alloy exhibit considerable differences in bending formability and crack propagation behavior,depending on the distribution and number density of precipitates in the *** bending specimens of the AZ111 alloy,it is found that the failure bending strain(ε_(f,bending))is inversely proportional to the area fraction of precipitates in the outer zone of bending specimen(A_(ppt)),with a relation

关键词： Mg–Al alloy Extrusion Bending Precipitation Microstructure

Comparisons of oxbow lake fish assemblages in relation to bigheaded carp establishment in the lower White River, Arkansas

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Ecological Processes 2024年第1期13卷 188-205页

作者： Michael A.Eggleton Cody J.Salzmann joseph E.Kaiser Shannon C.f.Smith Department of Aquaculture and fisheries University of Arkansas at Pine Bluff Arkansas Game and fish Commission Virginia Institute of Marine Science

Background Since the late 1990s, bigheaded carps(largely silver carp [Hypophthalmichthys molitrix] but also bighead carp [H. nobilis]) have established throughout the lower Mississippi River basin. Using previously studied oxbow lakes in the lower White River basin, Arkansas, we compared current(2017, “post-carp” establishment) fish assemblages to historical(2002, “pre-carp” establishment) fish assemblages. fish assemblages were comprehensively assessed using multiple gears, including boat electrofishing, mini-fyke nets, and experimental small-mesh gill *** T-tests suggested that fish assemblage indices of richness, diversity, evenness, and dominance were often greater(P flected by boat electrofishing and experimental gill nets. However, all indices were generally similar(P > 0.05) between the pre-carp and post-carp period with fish assemblages depicted using mini-fyke nets. Nonmetric multidimensional scaling analyses indicated that fish assemblages differed structurally between pre-carp and post-carp periods. Assemblage differences were linked to both small and large abundance changes for more than 20 species. Abundances of gizzard shad(Dorosoma cepedianum), emerald shiner(Notropis atherinoides), pugnose minnow(Opsopoeodus emiliae), crappies(Pomoxis spp.), bluegill(Lepomis macrochirus), orangespotted sunfish(L. humilis), and yellow bass(Morone mississippiensis) declined between the pre-carp and postcarp periods. Conversely, abundances of weed shiner(N. texanus), pallid shiner(Hybopsis amnis), longear sunfish(L. megalotis), buffalofishes(Ictiobus spp.), and gars(Lepisosteus spp.) generally increased during the same *** Although not possible to conclude assemblage shifts were entirely related to bigheaded carps due to the absence of an appropriate reference system where carps did not establish, the wide establishment of these carps is one of the most pervasive changes to have occurred in the lower White

关键词： Bigheaded carp Silver carp Aquatic nuisance species fish assemblage Oxbow lake Large river

The global stability and optimal control of the COVID-19 epidemic model

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International journal of Biomathematics 2024年第1期17卷 1-28页

作者： fengsheng Chien Hassan Saberi Nik Mohammad Shiraziant J.f.Gomez-Aguilar School of finance and Accounting fuzhou University of International Studies and Trade fuzhou 352020 P.R.China faculty of Business City university of Macao Macao 999078P.R.China Department of Mathematics and Statistics University of Neyshabur NeyshaburIran CONACyT-Tecnologico Nacional de Mécico/CENIDET Interior Internado Palmira S/N Col.Palmira C.P.62490CuernavacaMorelosMérico

This paper considers stability analysis of a Susceptible-Exposed-Infected-Recovered-Virus(SEIRV)model with nonlinear incidence rates and indicates the severity and weakness of control factors for disease *** Lyapunov function using Volterra-Lyapunov matrices makes it possible to study the global stability of the endemic equilibrium *** optimal control strategy is proposed to prevent the spread of coronavirus,in addition to governmental *** objective is to minimize together with the quantity of infected and exposed individuals while minimizing the total costs of treatment.A numerical study of the model is also carried out to investigate the analytical results.

关键词： Global stability SEIRV epidemic model dynamical systems Volterra-Lyapunov stability optimal control

Testicular prostheses-impact on quality of life and sexual function

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Asian journal of Andrology 2024年第2期26卷 160-164页

作者： Ana Sofia araujo Sara Anacleto Ricardo Rodrigues Catarina Tinoco Andreia Cardoso Carlos Oliveira Ricardo Leao Department of Urology Braga's HospitalBraga 4710Portugal faculty of Medicine Coimbra UniversityCoimbra 3000Portugal

Orchiectomy is the recommended treatment for many testicular ***,testicular prosthesis placement is not always performed for different *** this study,we aimed to evaluate patients'opinions and the impact on sexual function and quality of *** retrospective observational single-center study included patients who underwent orchiectomy between January 2014 and December 2020 at the Department of Urology,Braga's Hospital(Braga,Portugal),where testicular implants were always available and the decision to undergo the procedure was made fully independent of *** completed four questionnaires that assessed demographic data,satisfaction,self-esteem,and sexual *** the 96 patients who underwent orchidectomy,59 replied to the questionnaires,and of these patients,86.4%decided to undergo silicone-based testicular prostheses *** remaining 13.6%refused the implant based on concerns about complications(37.5%),because they felt that it was unnecessary(37.5%),or because it was not offered by the doctor(25.0%).Overall,96.1%of these patients were satisfied with the implant;however,25.5%classified it as"too firm".No statistically significant differences were found in sexual function(all P>0.05).However,it can be observed that there are more patients with prostheses presenting normal sexual activity compared to patients without prostheses(74.0%vs 50.0%),and none of them reported severe erectile dysfunction(0 vs 16.7%).Regarding self-esteem,both patients with and without prostheses present very similar average scores with no statistically significant *** present study highlights the highest level of satisfaction among patients who received testicular *** prostheses implantation is a safe procedure that does not hamper sexual function after orchiectomy.

关键词： orchiectomy patient satisfaction quality of life sexual dysfunction sexual health testicular prostheses

Small molecular decoys in Alzheimer's disease

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Neural Regeneration Research 2024年第8期19卷 1658-1659页

作者： Sho Oasa Valentina L.Kouznetsova Igor f.Tsigelny Lars Terenius Department of Clinical Neuroscience Center for Molecular MedicineKarolinska InstitutetStockholmSweden San Diego Supercomputer Center University of California San DiegoLa JollaCAUSA Department of Neurosciences University of California San DiegoLa JollaCAUSA Department of Clinical Neuroscience Karolinska University HospitalKarolinska InstitutetStockholmSweden

Recent progress in the treatment of Alzheimer’s disease(AD)using antibodies against amyloid sustains amyloid generation as a key process in *** formation starts with two amyloidbeta(Aβ)molecules interacting(dimer formation)followed by an accelerating build-up of socalled protofibrils,which turn into fibrils,which accumulate in the characteristic plaques.

关键词： Alzheimer decoy Aβ

Thermoluminescence characterization of natural and synthetic irradiated Ce-monazites

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journal of Rare Earths 2024年第4期42卷 643-650页

作者： V.Correcher C.Boronat J.Garcia-Guinea J.f.Benavente T.Rivera-Montalvo CIEMAT Av.Complutense 4028040MadridSpain MNCN-CSIC J.Gutierrez Abascal 228006MadridSpain Instituto Politécnico Nacional CICATA-IPNAv.Legaria 694Mexico City11500Mexico

The thermoluminescence(TL)emission of synthetic and natural Ce-monazites was characterized here to determine the potential application in the identification of microscopic defects from a qualitative point of view trying to link each TL peak to a chemical-physical *** kinetic parameters that lead the luminescence processes were calculated by means of variable heating rate and computing glow curve deconvolution methods and allow identifying three groups of components at~90,130 and 290℃(for the mineral sample)and~90,170,220,270 and 320℃(for the synthetic CePO_(4):Nd_(0.20),La_(0.25)).The main differences appreciated in these complex TL curves are mainly due to(i)the content of impurities(natural sample contains lanthanides as well as U 0.60%and Th 5.22%)and(ii)the degree of crystallinity of the samples which is directly related to the type of impurities(synthetic monazite relies only on Nd and La).The behavior of the dose response in the range of 1-8 Gy is similar for both samples;the TL intensity increases linearly as the dose increases without changes in the position of the maxima,denoting first-order kinetic luminescence *** peak could be mostly associated with structural defects(i.e.,phase transitions),chemical reactions(i.e.,Ce3+?Ce4+redox reaction,dehydration or dehydroxylation processes)or intrinsic defects(i.e.,frenkel defects,ODCs or NBOHCs).

关键词： Thermoluminescence Kineticparameters Phosphate Ce-monazite Defects Rare earths

Microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with different prestrain levels

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journal of Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.H.Zhang H.Li Z.W.Yang X.Liu Q.f.Gu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of High-Performance Precision forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SMA)is a promising material in the aerospace field due to its wide transformation *** application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to ***-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of SMA ***,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)SMA subjected to vari-ous prestrain levels are still *** this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(M_(s)+30℃)were *** results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.Whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,*** stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb *** stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SIMVs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced ***{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density of{114}austenite twins form in the specimen with a larger prestrain of 16%.With increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then ***ε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%*** increase ofε_(re)^(T)can be attributed to the formation of new SIMVs,the further growth of existing SIMVs,and the recoverable(001)compound *** the decrease ofε_(re)^(T)is mainly associated with the irrecoverable strain by{20−1}martensite *** effe

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy Wide transformation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

Stochastic seismic inversion and Bayesian facies classification applied to porosity modeling and igneous rock identification

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Petroleum Science 2024年第2期21卷 918-935页

作者： fábio Júnior Damasceno fernandes Leonardo Teixeira Antonio fernando Menezes freire Wagner Moreira Lupinacci Exploratory Interpretation and Reservoir Characterization Group(GIECAR) Department of Geology and GeophysicsFederal Fluminense UniversityNiter oiRJ24210-346Brazil Petrobras Rio de JaneiroRJ20231-030Brazil National Institute of Science and Technology of Petroleum Geophysics(INCT-GP/CNPQ) Niter oiRJ24210-346Brazil

We apply stochastic seismic inversion and Bayesian facies classification for porosity modeling and igneous rock identification in the presalt interval of the Santos Basin. This integration of seismic and well-derived information enhances reservoir characterization. Stochastic inversion and Bayesian classification are powerful tools because they permit addressing the uncertainties in the model. We used the ES-MDA algorithm to achieve the realizations equivalent to the percentiles P10, P50, and P90 of acoustic impedance, a novel method for acoustic inversion in presalt. The facies were divided into five: reservoir 1,reservoir 2, tight carbonates, clayey rocks, and igneous rocks. To deal with the overlaps in acoustic impedance values of facies, we included geological information using a priori probability, indicating that structural highs are reservoir-dominated. To illustrate our approach, we conducted porosity modeling using facies-related rock-physics models for rock-physics inversion in an area with a well drilled in a coquina bank and evaluated the thickness and extension of an igneous intrusion near the carbonate-salt interface. The modeled porosity and the classified seismic facies are in good agreement with the ones observed in the wells. Notably, the coquinas bank presents an improvement in the porosity towards the top. The a priori probability model was crucial for limiting the clayey rocks to the structural lows. In Well B, the hit rate of the igneous rock in the three scenarios is higher than 60%, showing an excellent thickness-prediction capability.

关键词： Stochastic inversion Bayesian classification Porosity modeling Carbonate reservoirs Igneous rocks

Estimation of monthly global solar radiation over twelve major cities of Libya

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Energy and Built Environment 2024年第1期5卷 46-57页

作者： Alhassan Ali Teyabeen Najeya B.Elhatmi Akram A.Essnid f.Mohamed Libyan Center for Solar Energy Research and Studies TripoliLibya Libyan Authority of Scientific Research TripoliLibya

This study aims to estimate monthly averaged daily horizontal global solar *** climatological data collected at twelve major cities located across Libya’s map were used to establish 7 different empirical *** empirical coefficients of the models were calculated using the least square *** accuracy of the models was evaluated using different statistical criteria such as Taylor diagram,mean absolute percentage error,MAPE,and root mean square error,*** results indicated that the sunshine duration-based models are more accurate than air temperature-based models,and the best performance was obtained by the quadratic regression model for all twelve Libyan ***,this regression model can be used for the prediction of monthly mean horizontal global solar radiation at a specific site across Libya’s regions with minimum ***,the results of the global solar irradiance produced by this method can be used for designing solar systems applications.

关键词： Monthly global solar radiation Clearness index Empirical models Performance evaluation Taylor diagram Libya