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Influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel

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Applied mathematics and mechanics(English Edition) 2024年第3期45卷 563-580页

作者： n.HUmnEKAR D.sRInIVAsACHARYA Department of mathematics National Institute of TechnologyWarangal 506004TelanganaIndia

The influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel is *** DarcyBrinkman model is used to characterize the fluid flow dynamics in porous *** analytical solutions are obtained for the unidirectional and completely developed *** on a normal mode analysis,the generalized eigenvalue problem under a perturbed state is *** eigenvalue problem is then solved by the spectral ***,the critical Rayleigh number with the corresponding wavenumber is evaluated at the assigned values of the other flow-governing *** results show that increasing the Darcy number,the Lewis number,the Dufour parameter,or the soret parameter increases the stability of the system,whereas increasing the inclination angle of the channel destabilizes the ***,the flow is the most unstable when the channel is vertically oriented.

关键词： nanofluid inclined channel variable viscosity linear stability double dif-fusion porous medium

Influence of biomass burning on ozone levels in the megalopolis of Central mexico during the COVID-19 lockdown

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Journal of Environmental sciences 2024年第9期143卷 99-115页

作者： Victor Almanza Luis Gerardo Ruiz-suárez Ricardo Torres-Jardón Agustín García-Reynoso Iván Y.Hernández-Paniagua Institute for Atmospheric sciences and Climate Change National Autonomous University of MexicoCoyoacan 04510Mexico CityMexico

The massive reductions in anthropogenic emissions resulting from the COVID-19 lockdown provided a unique opportunity to evaluate the effect of mitigation measures aiming to abate air *** mexico,the total lockdown period took place during the dry-hot season when biomass burning activity is ***,we investigate the role of biomass burning emissions on regional ozone levels in the megalopolis of Central *** studied period covers the lockdown phases 2 and 3,and the first month of the new *** applied a factor separation technique and process analysis to estimate the pure and synergistic contributions of emission reductions under lockdown and that from biomass burning to daily ozone maximum concentrations in 7 metropolitan areas of different states in the *** results revealed that biomass burning plumes likely masked the effect of massive reductions from mobile emissions,impacted the PBL development during phase 3 and favored transition and mixed nO_(x)-limited and VOC-limited regional *** contributed to increased ozone production in the middle to lower PBL by changing the regional background levels which potentially could bias high ozone production efficiency *** the megalopolis contribution to economic and societal development at national scale,our study suggests that ozone mitigation measures during the dry-hot season targeting mainly mobile emissions will likely be offset by biomass burning plumes.A regional and synergic policy aiming to control biomass burning would help to reduce the occurrence of high ozone levels in Central mexico with the co-benefit of tackling short-lived climate pollutants.

关键词： COVID-19 mexico megalopolis Ozone Factor separation Process Analysis

Effect of Al_(2)O_(3)on the mechanical Properties of(B_(4)C+Al_(2)O_(3))/Al neutron Absorbing materials

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Acta metallurgica sinica(English Letters) 2024年第8期37卷 1411-1420页

作者： J.X.Cai B.m.shi n.Li Y.Liu Z.G.Zhang Y.n.Zan Q.Z.Wang B.L.Xiao Z.Y.ma shi‑Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of nuclear materials and safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China nuclear Equipment Division Beijing Institute of Nuclear EngineeringChina Nuclear Power Engineering Co.Ltd.Beijing 100840China Department of materials science School of Mechanical EngineeringShenyang UniversityShenyang 110044China

B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear *** order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder *** this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al *** was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high *** the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased *** finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 mPa at room temperature and 133 mPa at 350℃,surpassing that of traditional B_(4)C/Al composites.

关键词： Al matrix composites neutron absorbing materials (B_(4)C+Al_(2)O_(3))/Al composites High-temperature strength

Ranking environmental and edaphic attributes driving soil microbial community structure and activity with special attention to spatial and temporal scales

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mLife 2024年第1期3卷 21-41页

作者： Vadakattu V.s.R.Gupta James m.Tiedje CsIRO Agriculture&Food UrrbraeSouth AustraliaAustralia Centre for microbial Ecology Michigan State UniversityEast LansingMichiganUSA

The incredibly complex soil microbial communities at small scales make their analysis and identification of reasons for the observed structures *** community structure is mainly a result of the inoculum(dispersal),the selective advantages of those organisms under the habitat-based environmental attributes,and the ability of those colonizers to sustain themselves over *** soil is protective,and its microbial inhabitants have long adapted to varied soil conditions,significant portions of the soil microbial community structure are likely ***,a substantial portion of the community will not correlate to often measured soil *** suggest that the drivers be ranked on the basis of their importance to the fundamental needs of the microbes:(i)those that supply energy,i.e.,organic carbon and electron acceptors;(i)environmental effectors or stressors,i.e.,pH,salt,drought,and toxic chemicals;(ii)macro-organism associations,i.e.,plants and their seasonality,animals and their fecal matter,and soil fauna;and(iv)nutrients,in order,n,P,and probably of lesser importance,other micronutrients,and *** relevance of drivers also varies with spatial and time scales,for example,aggregate to field to regional,and persistent to dynamic populations to transcripts,and with the extent of phylogenetic difference,hence phenotypic differences in organismal *** present a summary matrix to provide guidance on which drivers are important for particular studies,with special emphasis on a wide range of spatial and temporal scales,and illustrate this with genomic and population(rRnA gene)data from selected studies.

关键词： abundance community structure diversity functional microbiome microorganisms

Phase composition,conductivity,and sensor properties of cerium-doped indium oxide

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nano materials science 2024年第2期6卷 193-200页

作者： m.I.Ikim G.n.Gerasimov V.F.Gromov O.J.Ilegbusi L.I.Trakhtenberg n.n.semenov Federal Research Center for Chemical Physics of RAs MoscowRussia University of Central Florida OrlandoFLUSA moscow Institute of Physics and Technology(state University) DolgoprudnyMoscow RegionRussia Lomonosov moscow state University MoscowRussia

The hydrothermal synthesis of In_(2)O_(3)and CeO_(2)–In_(2)O_(3)is investigated as well as the properties of sensor layers based on these *** the synthesis of In_(2)O_(3),intermediate products In(OH)_(3)and InOOH are formed,which are the precursors of stable cubic(c-In_(2)O_(3))and metastable rhombohedral(rh-In_(2)O_(3))phases,respectively.A transition from c-In_(2)O_(3)to rh-In_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-In_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-In_(2)O_(3).The data on the sensor activity of the composites correlate with XPs results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-In_(2)O_(3).The reverse situation is observed in composites based on c-In_(2)O_(3).Compared to In_(2)O_(3)and CeO_(2)–In_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between In_(2)O_(3)and CeO_(2).

关键词： Cerium oxide Indium oxide nanocomposite Hydrothermal method Cubic phase Rhombohedral phase sensor response Conductivity Hydrogen Response/recovery time

Unraveling the nature of sensing in electrostatic mEms gas sensors

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microsystems & nanoengineering 2024年第3期10卷 109-117页

作者： Yasser s.shama sasan Rahmanian Hamza mouharrar Rana Abdelrahman Alaaeldin Elhady Eihab m.Abdel-Rahman systems Design Engineering University of Waterloo200 University Ave WWaterloo N2L 3G1 ONCanada mechanical Engineering Benha Faculty of EngineeringBenha UniversityBenha 13511Egypt

This paper investigates the fundamental sensing mechanism of electrostatic mEms gas *** compares among the responsivities of a set of mEms isopropanol sensors before and after functionalization,and in the presence and absence of electrostatic fields when operated in static and dynamic detection *** the static mode,we found that the sensors do not exhibit a measurable change in displacement due to added *** the other hand,bare sensors showed a clear change in displacement in response to isopropanol *** the dynamic mode,functionalized sensors showed a measurable frequency shift due to the added mass of isopropanol *** the presence of strong electrostatic fields,the measured frequency shift was found to be threefold larger than that in their absence in response to the same concentration of isopropanol *** enhanced responsivity of dynamic detection allows the sensors to measure the vapor mass captured by the functional material,which is not the case for static *** detection of isopropanol by bare sensors in static mode shows that change in the medium permittivity is the primary sensing *** enhanced responsivity of dynamic mode sensors when operated in strong electrostatic fields shows that their sensing mechanism is a combination of a weaker added mass effect and a stronger permittivity *** findings show that electrostatic mEms gas sensors are independent of the direction of the gravitational field and are,thus,robust to changes in *** is erroneous to refer to them as‘gravimetric’sensors.

关键词： mechanism electrostatic measurable

Telomeric DnA breaks in human induced pluripotent stem cells trigger ATR-mediated arrest and telomerase-independent telomere damage repair

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Journal of molecular Cell Biology 2024年第3期16卷 46-60页

作者： Katrina n.Estep John W.Tobias Rafael J.Fernandez Brinley m.Beveridge F.Brad Johnson Department of Pathology and Laboratory medicine University of PennsylvaniaPhiladelphiaPA 19104USA Quantiative Biosciences Merck&Co.Inc.West PointPA 19486USA Penn Genomic Analysis Core University of PennsylvaniaPhiladelphiaPA 19104USA

Although mechanisms of telomere protection are well-defined in differentiated cells,how stem cells sense and respond to telomere dysfunction,in particular telomeric double-strand breaks(DsBs),is poorly ***,we report the DnA damage signaling,cell cycle,and transcriptome changes in human induced pluripotent stem cells(iPsCs)in response to telomere-internal *** engineer human iPsCs with an inducible TRF1-FokI fusion protein to acutely induce DsBs at *** this model,we demonstrate that TRF1-FokI DsBs activate an ATR-dependent DnA damage response,which leads to p53-independent cell cycle arrest in *** CRIsPR–Cas9 to cripple the catalytic domain of telomerase reverse transcriptase,we show that telomerase is largely dispensable for survival and lengthening of TRF1-FokI-cleaved telomeres,which instead are effectively repaired by robust homologous recombination(HR).In contrast to HR-based telomere maintenance in mouse embryonic stem cells,where HR causes ZsCAn4-dependent extension of telomeres beyond their initial lengths,HR-based repair of telomeric breaks is sufficient to maintain iPsC telomeres at a normal length,which is compatible with sustained survival of the cells over several days of TRF1-FokI *** findings suggest a previously unappreciated role for HR in telomere maintenance in telomerase-positive iPsCs and reveal distinct iPsC-specific responses to targeted telomeric DnA damage.

关键词： telomeres telomerase alternative lengthening of telomeres pluripotent stem cells DnA damage double-strand breaks

structural stability of the Financial market model: Continuity of superhedging Price and model Approximation

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Journal of the Operations Research society of China 2024年第1期12卷 215-241页

作者： sergey n.smirnov Faculty of Computational mathematics and Cybernetics Lomonosov Moscow State UniversityMoscow119991Russian Federation

The present paper continues the topic of our recent paper in the same journal,aiming to show the role of structural stability in financial *** the context of financial market modeling,structural stability means that a specific“no-arbitrage”property is unaffected by small(with respect to the Pompeiu–Hausdorff metric)perturbations of the model’s *** formulate,based on our economic interpretation,a new requirement concerning“no arbitrage”properties,which we call the“uncertainty principle”.This principle in the case of no-trading constraints is equivalent to structural *** demonstrate that structural stability is essential for a correct model approximation(which is used in our numerical method for superhedging price computation).We also show that structural stability is important for the continuity of superhedging prices and discuss the sufficient conditions for this continuity.

关键词： Uncertainty structural stability no arbitrage Continuity of superhedging price Compact-valued multifunction Financial market model approximation Trading constraints

maximizing aged photovoltaic array power:a computer modelling study

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Clean Energy 2024年第1期8卷 171-187页

作者： Fadi n.sibai Electrical&Computer Engineering Department Gulf University for Science and TechnologyMishrefKuwait

Photovoltaic(PV)modules age with time for various reasons such as corroded joints and terminals and glass coating defects,and their ageing degrades the PV array *** the help of the PV array numerical model,this paper explores the effects of PV module ageing on the PV array power,and the power gains and costs of rearranging and recabling aged PV modules in a PV *** numerical PV array model is first revised to account for module ageing,rearrangement and recabling,with the relevant equations presented *** updated numerical model is then used to obtain the array powers for seven different PV *** power results are then analysed in view of the attributes of the seven PV array examples.A guiding method to recommend recabling after rearranging aged modules is then proposed,leading to further significant power gains,while eliminating intra-row *** certain conditions are met,it was shown that recabling PV modules after rearranging them may lead to further significant power gains,reaching 57%and 98%in two considered PV array *** gains are possible in other arrays.A cost-benefit analysis weighing annual power gains versus estimated recabling costs is also given for the seven considered PV array examples to guide recabling decisions based on technical and economic *** the considered examples,recabling costs can be recovered ins of the aged arrays,power gains due to our proposed rearranging and recabling the PV arrays ranged between 73%and 131%in the considered examples—well over the gains reported in the ***,the cost of our static module rearrangement and recabling method outshines the costs of dynamic reconfiguration methods recently published in the literature.

关键词： solar energy optimizing array power photovoltaic array modelling photovoltaic modules ageing photovoltaic module rearrangement module recabling and reconfiguration PV array mismatch