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An in vitro demonstration of a passive,acoustic metamaterial as a temperature sensor with mK resolution for implantable applications

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Microsystems & Nanoengineering 2024年第1期10卷 41-54页

作者： Lucrezia Maini Vicente Genovés Roman Furrer Nikola Cesarovic Christofer Hierold Cosmin Roman Micro-and Nanosystems Department of Mechanical and Process EngineeringETH ZurichTannenstrasse 38092 ZurichSwitzerland. Translational Cardiovascular Technology Department of Health Science and TechnologyETH ZurichLeopold-Ruzicka-Weg 48093 ZurichSwitzerland. Transport at Nanoscale Interfaces Swiss Federal Laboratories for Materials Science and TechnologyEMPAÜberlandstrasse 1298600 DübendorfSwitzerland Department of Cardiothoracic and Vascular surgery Deutsches Herzzentrum der Charite(DHZC)13353 BerlinGermany

Wireless medical sensors typically utilize electromagnetic coupling or ultrasound for energy transfer and sensor interrogation.Energy transfer and management is a complex aspect that often limits the applicability of implantable sensor systems.In this work,we report a new passive temperature sensing scheme based on an acoustic metamaterial made of silicon embedded in a polydimethylsiloxane matrix.Compared to other approaches,this concept is implemented without additional electrical components in situ or the need for a customized receiving unit.A standard ultrasonic transducer is used for this demonstration to directly excite and collect the reflected signal.The metamaterial resonates at a frequency close to a typical medical value(5 MHz)and exhibits a high-quality factor.Combining the design features of the metamaterial with the high-temperature sensitivity of the polydimethylsiloxane matrix,we achieve a temperature resolution of 30 mK.This value is below the current standard resolution required in infrared thermometry for monitoring postoperative complications(0.1 K).We fabricated,simulated,in vitro tested,and compared three acoustic sensor designs in the 29-43℃(~302-316 K)temperature range.With this concept,we demonstrate how our passive metamaterial sensor can open the way toward new zero-power smart medical implant concepts based on acoustic interrogation.

关键词： passive resolution utilize

Paraneoplastic retinopathies: an update on pathogenesis, diagnosis and management

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Annals of Eye science 2024年第1期9卷 34-42页

作者： Akshay s.Thomas Tennessee Retina NashvilleTNUSA

The paraneoplastic retinopathies are a heterogeneous group of disorders with significant visual consequences occuring in the setting of a systemic malignancy.These conditions may be characterized by the presence of antiretinal antibodies and may predate or follow the diagnosis of an underlying malignancy.Herein I review the clinical findings,pathophysiology,laboratory testing and management of the paraneoplastic retinopathies:cancer-associated retinopathy(CAR),melanoma-associated retinopathy(MAR),bilateral diffuse uveal melanocytic proliferation(BDUMP)and paraneoplastic vitelliform maculopathy(PVM).The pathophysiology of the paraneoplastic retinopathies varies from molecular mimicry resulting in anti-retinal antibody production(CAR,MAR)to relases of soluble factors either by the primary tumor(BDUMP)and/or immune system in response to the primary tumor(PVM)which result in retinal and/or retinal pigment epithelium dysfunction.For each condition,structural and functional multimodal retinal testing can be helpful in establishing the diagnosis.Treatment for the paraneoplastic retinopathies involves a combination of treating the underlying malignancy plus additional local and/or systemic immunosuppressive agents though no systemic therapeutic protocols exist.Despite these interventions,the retinopathy may be progressive or the retinopathy may be a harbinger of poor survival.Nevertheless,prompt diagnosis may help identify an underlying malignancy earlier and may thus improve cancer-related survival.

关键词： Paraneoplastic retinopathy bilateral diffuse uveal melanocytic proliferation(BDUMP) cancer-associated retinopathy(CAR) vitelliform

Kinematic analysis of flexible bipedal robotic systems

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 795-818页

作者： R.FAZEL A.M.sHAFEI s.R.NEKOO Department of Mechanical Engineering Shahid Bahonar University of KermanKerman ***Iran Departamento de Ingenieria de sistemas y Automatica Escuela Técnica Superior de IngenieriaUniversidad de SevillaSeville 41092Spain

In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous researchers.What distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic systems.This is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases considerably.Moreover,the human leg bones that are involved in walking are supported by viscoelastic muscles and ligaments.Therefore,for achieving more exact results,it is essential to model the robot links with viscoelastic properties.To this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of motion.The most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational force.The extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned goal.To overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue problem.By solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are determined.The effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of robotic systems are also studied.The findings o

关键词： bipedal robot flexible link swing phase transient phase eigenvalue problem Kelvin-Voigt coefficient

Emission colour tuning in KLnF_(4):Yb^(3+),Er^(3+)/Ho^(3+)phosphor

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Journal of Rare Earths 2024年第1期42卷 57-65,I0002页

作者： Janani K Gayathri E Vijayatha V Ramasubramanian s Thiyagarajan P Department of science and Humanities Nehru Institute of TechnologyKaliapuramThirumalayampalayamCoimbatoreIndia Department of sciences Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatoreIndia Department of Physics Anna UniversityChennaiIndia

KLnF_(4):Yb^(3+),Er^(3+)/Ho^(3+)(Ln=Y,Yb,Gd)phosphors were prepared by solid-state reaction technique.For each of the Yb^(3+)/Er^(3+)and Yb^(3+)/Ho^(3+)co-doped phosphors independently,phase confirmation and morphological examination were accomplished using the X-ray diffraction technique and scanning electron microscope analysis.X-ray photoelectron spectroscopy analysis shows the charge state and existence of lanthanides and dopants.Upconversion luminescence emissions of green and red colour were detected for the synthesized phosphors.The changes in the upconverted emission intensities and colour output pertaining to the change of the lanthanide host matrix along with dopants were investigated for the prepared phosphors.In the upconversion luminescence,erbium-doped samples exhibit a predominance of red emission while holmium-doped samples display a prevalence of green emission.The rare-earth Er/Ho doped KYbF4shows strong red emission compared to other hosts.KYF_(4):Yb,Er/Ho exhibits relatively significant green upconve rsion emissions,while Yb,Er-doped KGdF_(4)host displays a 10-fold increase in green/red emission ratio with an increase in the input power of 20-780 mW.Downshifting photoluminescence studies and decay curve analysis were carried out using UV light excitation for the developed phosphors.A higher lifetime of 2.2 ms was measured for the downshifting red emission in the Ho doped KYbF_(4)sample.This study suggests a potential for colour tunability in the upconversion and downshifting emissions through host modifications to the fluoride phosphor.

关键词： Rare earths Energy transfer upconversion Downshifting Colour coordinates

Dynamics of a rotating ring-stiffened sandwich conical shell with an auxetic honeycomb core

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 963-982页

作者： s.JAHANGIRI A.GHORBANPOUR ARANI Z.KHODDAMI MARAGHI Department of solid Mechanics Faculty of Mechanical EngineeringUniversity of KashanKashan ***Iran Faculty of Engineering Mahallat Institute of Higher EducationMahallat ***Iran

The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied.The shell is modeled utilizing the first-order shear deformation theory(FsDT)incorporating the relative,centripetal,and Coriolis accelerations alongside the initial hoop tension created by the rotation.The governing equations,compatibility conditions,and boundary conditions are attained using Hamilton’s principle.Utilizing trigonometric functions,an analytical solution is derived in the circumferential direction,and a numerical one is presented in the meridional direction via the differential quadrature method(DQM).The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are studied.The present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support.

关键词： free vibration conical shell rotating shell ring support auxetic honeycomb

Optimum Profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic Performance

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Journal of Harbin Institute of Technology(New series) 2024年第2期31卷 80-92页

作者： Arjun K s Tide P s Biju N Division of Mechanical Engineering School of EngineeringCochin University of Science&TechnologyKalamassery 682022India

successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization.

关键词： endwall contouring turbine vane heat transfer phantom cooling coolant injection net heat flux reduction aerodynamic performance

Cr-induced fusion reactions to synthesize superheavy elements

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Nuclear science and Techniques 2024年第5期35卷 122-130页

作者： s.Madhu H.C.Manjunatha N.sowmya B.M.Rajesh L.seenappa R.s.susheela Department of Physics R V College of EngineeringBangalore 560074India Visvesvaraya Technological University BelagaviKarnataka 590018India Department of Physics Government First Grade CollegeSrinivasapurKarnataka 563135India Department of Physics Government First Grade CollegeDevanahallyKarnataka 562110India Department of Physics Government First Grade CollegeMulbagalKarnataka 563131India Department of Physics Government First Grade collegeNanjangudOoty RoadMysore 571301India

We investigated ^(50,52-54)Cr-induced fusion reactions for the synthesis of the superheavy element in the 104≤Z≤122 range.The cross sections produced in this investigation using ^(54)Cr projectiles were compared with those obtained in prior experiments.The estimated cross sections from this analysis are consistent with the findings of prior studies.From the current study,the predicted cross section was found to be 42fb at 236 MeV for ^(53)Cr+^(243)Am,23.2 fb at 236 MeV for ^(54)Cr+^(247)Cm,95.6 fb at 240 MeV for ^(53)Cr+248Bk,and 1.33 fb at 242 MeV for ^(53)Cr+250Cf.Consequently,these projected cross sections with excitation energy and beam energy will be useful in future Cr-induced fusion reaction investigations.

关键词： Fusion cross sections Compound nucleus formation probability survival probability Evaporation residue cross sections

Geochemistry and depositional environment of fuchsite quartzites from sargur Group,western Dharwar Craton,India

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Acta Geochimica 2024年第3期43卷 555-570页

作者： C.s.sindhuja G.Harshitha C.Manikyamba K.s.V.subramanyam CsIR(Council of scientific and Industrial Research)-National Geophysical Research Institute(NGRI) Uppal RoadHyderabad 500007India

Meso-Neoarchean fuchsite quartzites are present in different stratigraphic positions of Dharwar Craton including the oldest(~3.3 Ga)sargur Group of western Dharwar Craton.The present study deals with the petro-graphic and geochemical characteristics of the fuchsite quartzites from the Ghattihosahalli belt to evaluate their genesis,depositional setting and the enigma involved in the ancient sedimentation history.Their major mineral assemblages include quartz,fuchsite,and feldspars along with accessory kyanite and rutile.The geochemical com-positions are characterized by high siO_(2),Al_(2)O_(3),low MgO,CaO,strongly enriched Cr(1326–6899 ppm),Ba(1165–3653 ppm),sr(46–210 ppm),V(107–868 ppm)and Zn(11–158 ppm)contents compared to the upper continental crust(UCC).The UCC normalized rare earth element(REE)patterns are characterized by depleted light REE[(La/sm)UCC=0.33–0.95]compared to heavy REE[(Gd/Yb)_(UCC)=0.42–1.65]with conspicuous positive Eu-anomalies(Eu/Eu^(*)=1.35–18.27)characteristic of hydrothermal solutions evidenced through the interlayered barites.The overall major and trace element systematics reflect a combined mafic-felsic provenance and suggest their deposition at a passive continental margin environ-ment.The comprehensivefield,petrographic,and geo-chemical studies indicate that these quartzites are infiltrated by Cr-richfluids released during high-grade metamorphism of associated ultramafic rocks.The sargur and the subse-quent Dharwar orogeny amalgamated diverse lithounits from different tectonic settings,possibly leading to the release of Cr-richfluids and the formation of fuchsite quartzite during or after the orogeny.Thesefindings sug-gest a pre-existing stable crust prior to the sargur Group and the link between orogenic events and various mineral deposits in the Dharwar Craton.

关键词： Dharwar Craton Ghattihosahalli Fuchsite quartzite Provenance Depositional setting

Contribution of glial cells to the neuroprotective effects triggered by repetitive magnetic stimulation:a systematic review

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Neural Regeneration Research 2024年第1期19卷 116-123页

作者： susana A.Ferreira Nuno Pinto Inês serrenho Maria Vaz Pato Graça Baltazar Centro de Investigação em Ciências da saúde(CICs-UBI) Universidade da Beira InteriorCovilhãPortugal Faculdade de Ciências da saúde Universidade da Beira InteriorCovilhãPortugal GRUBI-systematic Reviews Group University of Beira InteriorCovilhãPortugal

Repetitive transcranial magnetic stimulation has been increasingly studied in different neurological diseases,and although most studies focus on its effects on neuronal cells,the contribution of nonneuronal cells to the improvement trigge red by repetitive transcranial magnetic stimulation in these diseases has been increasingly suggested.To systematically review the effects of repetitive magnetic stimulation on non-neuronal cells two online databases.Web of science and PubMed were searched fo r the effects of high-frequency-repetitive transcranial magnetic stimulation,low-frequencyrepetitive transcranial magnetic stimulation,intermittent theta-bu rst stimulation,continuous thetaburst stimulation,or repetitive magnetic stimulation on non-neuronal cells in models of disease and in unlesioned animals or cells.A total of 52 studies were included.The protocol more frequently used was high-frequency-repetitive magnetic stimulation,and in models of disease,most studies report that high-frequency-repetitive magnetic stimulation led to a decrease in astrocyte and mic roglial reactivity,a decrease in the release of pro-inflammatory cyto kines,and an increase of oligodendrocyte proliferation.The trend towards decreased microglial and astrocyte reactivity as well as increased oligodendrocyte proliferation occurred with intermittent theta-burst stimulation and continuous theta-burst stimulation.Few papers analyzed the low-frequency-repetitive transcranial magnetic stimulation protocol,and the parameters evaluated were restricted to the study of astrocyte reactivity and release of pro-inflammatory cytokines,repo rting the absence of effects on these paramete rs.In what concerns the use of magnetic stimulation in unlesioned animals or cells,most articles on all four types of stimulation reported a lack of effects.It is also important to point out that the studies were developed mostly in male rodents,not evaluating possible diffe rential effects of repetitive transcranial magnetic stimulation between sexes.This systematic revi

关键词： astrocyte glia high-frequency repetitive magnetic stimulation inflammation low-frequency repetitive magnetic stimulation microglia neurologic disorders oligodendrocyte repetitive magnetic stimulation theta-burst stimulation