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Ultra-wide band gap and wave attenuation mechanism of a novel star-shaped chiral metamaterial

Applied Mathematics and Mechanics(English Edition) 2024年第7期45卷 1261-1278页

作者： Shuo WANg Anshuai WANg Yansen WU Xiaofeng LI Yongtao SUN Zhaozhan ZHANg Qian dINg g.d.AYALEW Yunxiang MA Qingyu LIN department of Mechanics Tianjin University Tianjin Key Laboratory of Nonlinear dynamics and Control Tianjin University State Key Laboratory of Metastable Materials Science and Technology Yanshan University

A novel hollow star-shaped chiral metamaterial(SCM) is proposed by incorporating chiral structural properties into the standard hollow star-shaped metamaterial, exhibiting a wide band gap over 1 500 Hz. To broaden the band gap,solid single-phase and two-phase SCMs are designed and simulated, which produce two ultra-wide band gaps(approximately 5 116 Hz and 6 027 Hz, respectively). The main reason for the formation of the ultra-wide band gap is that the rotational vibration of the concave star of two novel SCMs drains the energy of an elastic wave. The impacts of the concave angle of a single-phase SCM and the resonator radius of a two-phase SCM on the band gaps are studied. decreasing the concave angle leads to an increase in the width of the widest band gap, and the width of the widest band gap increases as the resonator radius of the two-phase SCM increases. Additionally,the study on elastic wave propagation characteristics involves analyzing frequency dispersion surfaces, wave propagation directions, group velocities, and phase velocities. Ultimately, the analysis focuses on the transmission properties of finite periodic structures. The solid single-phase SCM achieves a maximum vibration attenuation over 800, while the width of the band gap is smaller than that of the two-phase SCM. Both metamaterials exhibit high vibration attenuation capabilities, which can be used in wideband vibration reduction to satisfy the requirement of ultra-wide frequencies.

关键词： metamaterial ultra-wide band gap wave propagation vibration suppression O421 + .5 74H45

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Periodontitis:An often-neglected complication of diabetes

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World Journal of diabetes 2024年第3期15卷 318-325页

作者： Marina g Kudiyirickal Joseph M Pappachan Primary Care dental Practice The Smile ClinicPreston PR16PZUnited Kingdom department of Endocrinology and Metabolism Lancashire Teaching Hospitals NHS TrustPreston PR29HTUnited Kingdom Faculty of Science Manchester Metropolitan UniversityManchester M156BHUnited Kingdom Faculty of Biology Medicine and HealthThe University of ManchesterManchester M139PLUnited Kingdom

The bidirectional association between type 2 diabetes mellitus(T2dM)and periodontitis is now well established,resulting in periodontal disease being considered as the 6th major complication of diabetes mellitus(dM)after cardiovascular disease,eye disease,neuropathy,nephropathy,and peripheral vascular disease.dM can worsen the virulence and invasiveness of pathogenic oral microbial flora aggravating the local inflammation and infection in those with periodontal disease.On the other hand,the chemical and immunological mediators released into the circulation as part of periodontal inflammation worsen the systemic insulin resistance with worsening of T2dM.Periodontitis if undiagnosed or left untreated can also result in eventual tooth loss.A study by Xu et al in the World Journal of diabetes examined the predictive factors associated with periodontitis in Chinese patients with T2dM.The prevalence of periodontitis was found to be 75.7%in this study.Based on logistic regression analysis,the predictive factors for higher risk were low tooth brushing frequency[odds ratio(OR)=4.3],high triglycerides(Tg;OR=3.31),high total cholesterol(TC;OR=2.87),higher glycated hemoglobin(HbA1c;OR=2.55),and higher age(OR=1.05)while higher education level was protective(OR=0.53).However,the most influential variables were HbA1c followed by age,TC,Tg,low education level,brushing frequency,and sex on the random forest model(this model showed higher sensitivity for predicting the risk).A good understanding of the predictors for periodontitis in T2dM patients is important in prevention,early detection of susceptible patients,and intervention to improve periodontal health and enable long-term glycaemic control as observed by Xu et al.

关键词： diabetes mellitus Periodontitis Predictive factors Cardiovascular disease glycaemic control

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Improved Leap-frog Method for Time-domain Fault Location

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 670-674页

作者： Izudin džafić Rabih A.Jabr Faculty of Electrical Engineering University of SarajevoSarajevo 71000Bosnia and Herzegovina department of Electrical and Computer Engineering American University of BeirutBeirut 11072020Lebanon IEEE

The partial differential equation(PdE)solution of the telegrapher is a promising fault location method among time-domain and model-based techniques.Recent research works have shown that the leap-frog process is superior to other explicit methods for the PdE solution.However,its implementation is challenged by determining the initial conditions in time and the boundary conditions in space.This letter proposes two implicit solution methods for determining the initial conditions and an analytical way to obtain the boundary conditions founded on the signal decomposition.The results show that the proposal gives fault location accuracy superior to the existing leap-frog scheme,particularly in the presence of harmonics.

关键词： Fault location leap-frog partial differential equation time-domain analysis transmission line

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Numerical calculation of Z-scan measurements for nonlinear media with large phase shift

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Optoelectronics Letters 2024年第3期20卷 177-182页

作者： M.d.Zidan A.Allahham department of Physics Atomic Energy Commission of SyriaP.O.Box 6091DamascusSyria

We have reported the characteristics of a Z-scan for the poly(azaneylylidene-acylene)(dAZA) polymer, as nonlinear medium with a large nonlinear phase shift using continuous-wave(CW) laser beam. It has been verified that the Fresnel diffraction model is applicable for analyses of Z-scan measurements with dAZA polymer at high laser power. It was found that Z-scan curves with peak-to-valley features appear as the applied light intensity increases in the case of a large nonlinear phase shift. The Z-scan experiments were carried out using a CW laser to verify the theoretical calculations in the case of a large nonlinear phase shift model. Our results show good agreements between the experimental data and the proposed theoretical models.

关键词： nonlinear phase media

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Magnesium oxide(MgO) nanoadsorbents in wastewater treatment: A comprehensive review

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Journal of Magnesium and Alloys 2024年第5期12卷 1709-1773页

作者： H.C.S.Perera V.gurunanthanan Anoop Singh M.M.M.g.P.g.Mantilaka g.das Sandeep Arya department of Physics Khalifa University Postgraduate Institute of Science University of Peradeniya department of Humanities and Sciences Guru Nanak Institutions Technical Campus Centre for global Health Research Saveetha Medical College and Hospitals Saveetha Institute of Medical and Technical Sciences department of Physics University of Jammu

Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge, necessitating effective and sustainable separation techniques. This review article provides a detailed examination of magnesium oxide(MgO) nanoparticles as an innovative nanoadsorbent for wastewater treatment, with a specific focus on heavy metal and dye removal. The review comprehensively explores various aspects of MgO nanoparticles, including their structural characteristics and synthesis techniques. The article delves into the morphology and crystallographic arrangement of MgO nanoparticles, offering insights into their structural attributes. given the complexity of adsorption processes, the review identifies and analyzes parameters influencing the adsorption efficiency of MgO nanoparticles, such as temperature, pH, contact time, initial concentration, and co-existing ions. The interplay between these parameters and the adsorption capability of MgO nanoparticles emphasizes the importance of optimizing operational conditions. Furthermore, the review assesses various synthesis methods for MgO nanoparticles, including sol-gel, hydrothermal, precipitation, green synthesis, solvothermal, and template-assisted techniques. It discusses the advantages, limitations, and resulting nanoparticle characteristics of each method, enabling readers to grasp the implications of synthesis processes on adsorption efficiency. This comprehensive review consolidates current insights into the effectiveness of MgO nanoparticles as a potent nanoadsorbent for removing heavy metals and dyes from wastewater covering a wide spectrum of aspects related to MgO nanoparticles. Moreover, there is a need to investigate the use of MgO in the treatment of actual wastewater or river water,in order to leverage its cost-effectiveness and high efficiency for practical water treatment applications in real-time.

关键词： MgO nanoparticles Nanoadsorbent Wastewater treatment Heavy metals dye separation Adsorption Synthesis methods

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Multiple sclerosis drug repurposing for neuroregeneration

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Neural Regeneration Research 2024年第3期19卷 507-508页

作者： Peter göttle Michael dietrich Patrick Küry department of Neurology Medical FacultyHeinrich-Heine UniversityDüsseldorfGermany

Multiple sclerosis(MS)is an autoimmune disorder of the central nervous system(CNS)and is primarily characterized by immune cell infiltration leading to relapses followed by remission phases and a disease course turning progressive over time with neurodegenerative processes taking over(Amin and Hersh,2023).Of note,beyond relapse-associated worsening early in disease progression independent of relapse activity may arise independently of relapse activity and can occur in all phenotypes.Autoimmune-mediated damage of myelin sheaths and the subsequent loss of mature oligodendrocytes are resulting in impaired axonal integrity,neurodegeneration and accounts for irreversible neuronal damage(Kuhlmann et al.,2023).The current landscape of available disease-modifying therapies comprises mainly immunomodulatory drugs that effectively diminish relapses and slow down progression at the onset form of the disease,namely relapsing MS(RMS).In this regard,a number of drugs have been approved as disease-modifying therapies for MS by US Food and drug Administration and European Medicines Agencies(Box 1).

关键词： drugs impaired irreversible

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Comparative measurement of CO_(2),CH_(4)and CO at two traffic interjunctions having inflated vehicular flow in delhi

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Journal of Environmental Sciences 2024年第7期141卷 314-329页

作者： Komal daya Soni Khem Singh Shankar g.Aggarwal CSIR-National Physical Laboratory Dr.K.S.Krishnan MargNew Delhi 110012India Academy of Scientific&Innovative Research(AcSIR) Ghaziabad 201002India

Vehicular emissions are considered one of the major anthropogenic sources of greenhouse gases and poor air quality in metropolitan cities.This study aims to see the correlation of CO_(2),CH_(4),and CO through monitoring over a period from december 2020 to October 2021 covering three seasons’winter,summer,and monsoon at two different traffic locations of delhi having different traffic volumes,road patterns,and traffic management.The annual average morning concentration of CO_(2),CH_(4)and CO was found(533±105),(7.3±3.1),(10.7±3.0)ppm at Najafgarh and(480±70),(5.2±1.8),(7.8±2.8)ppm at Rajendra Place,respectively.A relationship between concentration of all three gases and meteorological parameters such as temperature,humidity,wind speed and wind direction has also been investigated using Pearson correlation coefficient and pollution rose diagram.A comparable pattern in concentration was observed for all three gases in spatial(location)and temporal(diurnal)distribution.The concentration trend of CO_(2)in different seasons is winter>summer>monsoon,while in the case of CH_(4)winter=summer>monsoon but not any seasonal trend was noted in CO case.It is observed that CO_(2)has a good relation with CO(a tracer for vehicular emission)in terms of diurnal variation,whereas,CH_(4)does not represent a relation with CO and CO_(2)diurnally,suggesting that vehicles are the source of CO_(2)but not much contributing to other greenhouse gases like CH_(4).

关键词： Vehicular emission greenhouse gases Harmful pollutants Meteorological parameters

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ground-based and additional science support for SMILE

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Earth and Planetary Physics 2024年第1期8卷 275-298页

作者： J.A.Carter M.dunlop C.Forsyth K.Oksavik E.donovon A.Kavanagh S.E.Milan T.Sergienko R.C.Fear d.g.Sibeck M.Connors T.Yeoman X.Tan M.g.g.T.Taylor K.McWilliams J.gjerloev R.Barnes d.d.Billet g.Chisham A.dimmock M.P.Freeman d.-S.Han M.d.Hartinger S.-Y.W.Hsieh Z.-J.Hu M.K.James L.Juusola K.Kauristie E.A.Kronberg M.Lester J.Manuel J.Matzka I.McCrea Y.Miyoshi J.Rae L.Ren F.Sigernes E.Spanswick K.Sterne A.Steuwer T.Sun M.-T.Walach B.Walsh C.Wang J.Weygand J.Wild J.Yan J.Zhang Q.-H.Zhang Planetary Sciences group School of Physics and AstronomyUniversity of LeicesterUniversity RoadLeicesterLE17RHUK Rutherford Appleton Laboratory Space Science Technology Facilities CouncilOxfordshireUK School of Space and Environment Beihang UniversityBeijing 100191China Key Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100017China department of Space and Climate Physics UCLMullard Space Science LaboratoryHolmbury St.MaryDorkingSurreyRH56NTUK Birkeland Centre for Space Science Department of Physics and Technology.University of BergenBergenNorway department of Physics and Astronomy University of Calgary2500 University DriveCalgaryAlbertaCanada T2N 1N4 British Antarctic Survey CambridgeUK Swedish Institute of Space Physics KirunaSweden West Highfield Campus University of SouthamptonUniversity RoadSO171BJUK goddard Space Flight Center NASAGreenbeltMarylandUSA Athabasca University AthabascaCanada ESTEC European Space AgencyNetherlands University of Saskatchewan SaskatoonCanada The Johns Hopkins University Applied Physics Laboratory LaurelMarylandUSA Swedish Institude of Space Physics UppsalaSE 75121Sweden Tongji University Shanghai 200092China Center for Space Plasma Physics Space Science Institute4765 Walnut Street Suite BBoulderColorado80301USA Polar Research Institute of China Shanghai 200136China Finnish Meteorological Institute(FMI) Finland department of Earth and Environmental Sciences(geophysics) Ludwig Maximilian University of Munich(LMU)MunichTheresienstr.41MunichD-80333Germany Canadian Space Agency MontrealCanada gFZ german Research Centre for geosciences PotsdamGermany Nagoya University Institute for Space Earth Environment ResearchCenter for Integrated Data ScienceNagoyaAichiJP 464-8601 Northumbria University Newcastle upon TyneTyne and WearUK NE18ST National Space Science Center Chinese Academy SciencesBeijing 100190China Arctic geophysics University Centre in Svalbard

The joint European Space Agency and Chinese Academy of Sciences Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)mission will explore global dynamics of the magnetosphere under varying solar wind and interplanetary magnetic field conditions,and simultaneously monitor the auroral response of the Northern Hemisphere ionosphere.Combining these large-scale responses with medium and fine-scale measurements at a variety of cadences by additional ground-based and space-based instruments will enable a much greater scientific impact beyond the original goals of the SMILE mission.Here,we describe current community efforts to prepare for SMILE,and the benefits and context various experiments that have explicitly expressed support for SMILE can offer.A dedicated group of international scientists representing many different experiment types and geographical locations,the ground-based and Additional Science Working group,is facilitating these efforts.Preparations include constructing an online SMILE data Fusion Facility,the discussion of particular or special modes for experiments such as coherent and incoherent scatter radar,and the consideration of particular observing strategies and spacecraft conjunctions.We anticipate growing interest and community engagement with the SMILE mission,and we welcome novel ideas and insights from the solar-terrestrial community.

关键词： magnetosphere ionosphere magnetosphere-ionosphere coupling ground-based experimentation SMILE conjunctions missions

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Study of hybrid nanofluid flow in a stationary cone-disk system with temperature-dependent fluid properties

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 677-694页

作者： A.S.JOHN B.MAHANTHESH g.LORENZINI Center for Mathematical Needs Department of MathematicsCHRIST(Deemed to be University)Karnataka 560029India School of Mathematical and Statistical Sciences The University of Texas Rio Grande ValleyTexas 78539U.S.A. department of Engineering and Architecture University of ParmaParma 43124Italy

Cone-disk systems find frequent use such as conical diffusers,medical devices,various rheometric,and viscosimetry applications.In this study,we investigate the three-dimensional flow of a water-based Ag-Mg O hybrid nanofluid in a static cone-disk system while considering temperature-dependent fluid properties.How the variable fluid properties affect the dynamics and heat transfer features is studied by Reynolds's linearized model for variable viscosity and Chiam's model for variable thermal conductivity.The single-phase nanofluid model is utilized to describe convective heat transfer in hybrid nanofluids,incorporating the experimental data.This model is developed as a coupled system of convective-diffusion equations,encompassing the conservation of momentum and the conservation of thermal energy,in conjunction with an incompressibility condition.A self-similar model is developed by the Lie-group scaling transformations,and the subsequent self-similar equations are then solved numerically.The influence of variable fluid parameters on both swirling and non-swirling flow cases is analyzed.Additionally,the Nusselt number for the disk surface is calculated.It is found that an increase in the temperature-dependent viscosity parameter enhances heat transfer characteristics in the static cone-disk system,while the thermal conductivity parameter has the opposite effect.

关键词： hybrid nanofluid cone-disk system laminar flow variable fluid property Nusselt number

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Chebyshev polynomial-based Ritz method for thermal buckling and free vibration behaviors of metal foam beams

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 891-910页

作者： N.d.NgUYEN T.N.NgUYEN Faculty of Civil Engineering Ho Chi Minh City University of Technology and EducationHo Chi Minh City 71309Viet Nam Faculty of Engineering and Technology Kien Giang UniversityChau Thanh 92000Viet Nam

This study presents the Chebyshev polynomials-based Ritz method to examine the thermal buckling and free vibration characteristics of metal foam beams.The analyses include three models for porosity distribution and two scenarios for thermal distribution.The material properties are assessed under two conditions,i.e.,temperature dependence and temperature independence.The theoretical framework for the beams is based on the higher-order shear deformation theory,which incorporates shear deformations with higher-order polynomials.The governing equations are established from the Lagrange equations,and the beam displacement fields are approximated by the Chebyshev polynomials.Numerical simulations are performed to evaluate the effects of thermal load,slenderness,boundary condition(BC),and porosity distribution on the buckling and vibration behaviors of metal foam beams.The findings highlight the significant influence of temperature-dependent(Td)material properties on metal foam beams'buckling and vibration responses.

关键词： Ritz method Chebyshev function buckling vibration metal foam beam higher-order beam theory(HOBT)

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