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Improving Radiation Pattern Roundness of Henge-Like Metaring-Loaded Monopoles Above a Finite Ground for MIMO Systems

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Electromagnetic Science 2024年第2期2卷 104-115页

作者： Bo Zhang Zhi Ning Chen Yucong Zhou Qun Lou Jiahao Wang koen.mouthaan Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore Huawei Technologies Co. Ltd.Shenzhen 518129China

A henge-like metaring(HMR)is proposed for improving the radiation pattern roundness of monopole antennas offcenter mounted on a finite ground by localizing the radiation from the monopole and suppressing the scattering by the *** improved patterns enhance uniform coverage of multiple-input and multiple-output(MIMO)*** study reveals that the radiation pattern of an off-center monopole is distorted by the asymmetric ground currents excited by both the feed and the radiation of the *** distorted radiation patterns severely degrade wireless communication link *** HMR,composed of an annular array of mushroom unit cells,simultaneously functions as an electromagnetic bandgap(EBG)and a radiator,and encircles the monopole to form a henge monopole antenna(HMA).The HMR as an EBG is used to suppress the ground currents outside the HMR analyzed by an equivalent circuit *** HMR as a radiator is designed to decouple the monopole from the ground with its elevated radiation pattern using characteristic mode *** examples,two prototypes of single and four off-center MIMO HMAs are designed and investigated in the 2.45-GHz *** and measured results show that the single HMA and each of the four HMAs achieve the un-roundness of the radiation pattern atθ=65°plane lower than 2 dB and 3 dB in the 2.45-GHz *** a result,near the radiation nulls,the SNR is improved by 6 *** compact construction and efficient current suppression facilitate the application of HMAs in multi-antenna systems above a finite ground with uniform coverage and reliable connections.

关键词： Antenna radiation pattern Characteristic mode analysis Metamaterials MIMO communication Omnidirectional antennas Wireless access points

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Intraoperative application of three-dimensional printed guides in total hip arthroplasty: A systematic review

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World Journal of Orthopedics 2024年第7期15卷 660-667页

作者： Tim P Crone Bart M W Cornelissen Jakob Van Oldenrijk Pieter koen Bos Ewout S Veltman Department of Orthopedic Surgery and Sports Medicine Erasmus Medical CenterRotterdam 3015 GDNetherlands Department of Oral and Maxillofacial Surgery Erasmus Medical CenterRotterdam 3015 GDNetherlands

BACKGROUND Acetabular component positioning in total hip arthroplasty(THA)is of key importance to ensure satisfactory post-operative outcomes and to minimize the risk of *** majority of acetabular components are aligned freehand,without the use of navigation *** specific instruments(PSI)and three-dimensional(3D)printing of THA placement guides are increasingly used in primary THA to ensure optimal *** To summarize the literature on 3D printing in THA and how they improve acetabular component *** PubMed was used to identify and access scientific studies reporting on different 3D printing methods used in *** studies with 236 hips in 228 patients were *** studies could be divided into two main categories;3D printed models and 3D printed *** 3D printing in THA helped improve preoperative cup size planning and post-operative Harris hip scores between intervention and control groups(P=0.019,P=0.009).Otherwise,outcome measures were heterogeneous and thus difficult to *** overarching consensus between the studies is that the use of 3D guidance tools can assist in improving THA cup positioning and reduce the need for revision THA and the associated *** The implementation of 3D printing and PSI for primary THA can significantly improve the positioning accuracy of the acetabular cup component and reduce the number of complications caused by malpositioning.

关键词： Total hip arthroplasty Three-dimensional printing Hip replacement surgery Three-dimensional planning Surgical guides

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Association of Serum Folate and Vitamin B_(12) Concentrations with Obesity in Chinese Children and Adolescents

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Biomedical and Environmental Sciences 2024年第3期37卷 242-253页

作者： ZHU Qian Rang KOK E Dieuwertje BEKELE Hailu Tesfaye MANUSAMA koen ZHANG Jing Xian XIE Wei ZONG Wen Qi ZUO Hui ZHANG Jian KAMPMAN Ellen DAI Yue Jiangsu Provincial Center for Disease Control and Prevention Nanjing 210009JiangsuChina Division of Human Nutrition and Health Wageningen University&ResearchWageningen 176700 AAThe Netherlands School of Public Health Medical College of Soochow UniversitySuzhou 215123JiangsuChina National Institute for Nutrition and Health Chinese Center for Disease Control and PreventionBeijing 100050China

Objective This study aimed to evaluate the associations of serum folate and/or vitamin B12 concentrations with obesity among Chinese children and *** A cross-sectional study was conducted including 3,079 Chinese children and adolescents,aged 6 to 17 years,from Jiangsu,*** indices,such as,children's body mass index(BMI),BMI z-scores,waist circumference,and waist-to-height ratio were *** linear regression and generalized additive models were used to investigate the associations of serum folate and vitamin B12 levels with anthropometric indices and odds of *** We observed that serum vitamin B12 concentrations were inversely associated with all anthropometric indices and the odds of general obesity[odds ratio(OR)=0.68;95%confidence interval(CI)=0.59,0.78]and abdominal obesity(OR=0.68;95%CI=0.60,0.77).When compared to participants with both serum vitamin levels in the two middle quartiles,those with both serum folate and vitamin B12 levels in the highest quartile were less prone to general(OR=0.31,95%CI=0.19,0.50)or abdominal obesity(OR=0.46,95%CI=0.31,0.67).Conversely,participants with vitamin B12 levels in the lowest quartile alongside folate levels in the highest quartile had higher odds of abdominal obesity(OR=2.06,95%CI=1.09,3.91).Conclusion Higher serum vitamin B12 concentrations,but not serum folate concentrations,were associated with lower odds of childhood *** and adolescents with high levels of vitamin B12 and folate were less likely to be obese.

关键词： Folate Vitamin B12 Childhood obesity Micronutrient

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A new perspective on intervertebral disc calcification—from bench to bedside

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Bone Research 2024年第1期12卷 50-61页

作者： Emanuel J.Novais Rajkishen Narayanan Jose A.Canseco koen van de Wetering Christopher K.Kepler Alan S.Hilibrand Alexander R.Vaccaro Makarand V.Risbud Department of Orthopaedic Surgery Sidney Kimmel Medical CollegeThomas Jefferson UniversityPhiladelphiaPAUSA Unidade Local de Saúde do Litoral Alentejano Orthopedic DepartmentSantiago do CacémPortugal Rothman Orthopedic Institute at Thomas Jefferson University PhiladelphiaPAUSA

Disc degeneration primarily contributes to chronic low back and neck ***,there is an urgent need to understand the spectrum of disc degeneration phenotypes such as fibrosis,ectopic calcification,herniation,or mixed *** these phenotypes,disc calcification is the least *** calcification,by definition,is the pathological mineralization of soft tissues,widely studied in the context of conditions that afflict vasculature,skin,and ***,disc calcification is associated with poor surgical outcomes and back pain refractory to conservative *** is frequently seen as a consequence of disc aging and progressive degeneration but exhibits unique molecular and morphological characteristics:hypertrophic chondrocyte-like cell differentiation;TNAP,ENPP1,and ANK upregulation;cell death;altered Pi and PPi homeostasis;and local *** studies in mouse models have provided a better understanding of the mechanisms underlying this *** is essential to recognize that the presentation and nature of mineralization differ between AF,NP,and EP ***,the combination of anatomic location,genetics,and environmental stressors,such as aging or trauma,govern the predisposition to ***,the systemic regulation of calcium and Pi metabolism is less important than the local activity of PPi modulated by the ANK-ENPP1 axis,along with disc cell death and differentiation *** there is limited understanding of this phenotype,understanding the molecular pathways governing local intervertebral disc calcification may lead to developing disease-modifying drugs and better clinical management of degeneration-related pathologies.

关键词： degeneration metabolism intervertebral

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Molecularly horizontal stacking benefits charge separation through delocalized charge transfer states at donor-acceptor interfaces

Molecularly horizontal stacking benefits charge separation t...

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第十一届新型太阳能材料科学与技术学术研讨会

作者： Xiangkun Jia David Beljonne Donato Spoltore koen Vandewal Department of Physics Zhengzhou University Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics Technische Universit?t Dresden Laboratory for Chemistry of Novel Materials University of Mons Institute for Materials Research (IMO-IMOMEC) Hasselt University

The energetic landscape at the interface between electron donating and accepting molecular materials favors efficient conversion of intermolecular charge-transfer(CT) states into free charge carriers in high-performance organic solar ***,we elucidate how interfacial energetics,charge generation and radiative recombination are affected by molecular *** experimentally determine the CT dissociation properties of a series of model,small molecule donor-acceptor blends,where the used acceptors(B2PYMPM,B3PYMPM and B4PYMPM) differ only in the nitrogen position of their lateral pyridine rings.[1] We find that the formation of an ordered,face-on molecular packing in B4PYMPM is beneficial to efficient,field-independent charge separation,leading to fill factors above 70% in photovoltaic devices.[2] This is rationalized by a comprehensive computational protocol showing that,compared to the more amorphous and isotropically oriented B2PYMPM,the higher structural order in face-on B4PYMPM molecules leads to more delocalized CT ***,we find no correlation between the quantum efficiency of free charge carrier radiative recombination and the bound or unbound nature of the CT *** work highlights the importance of structural ordering at donor-acceptor interfaces for efficient free carrier generation and shows that less bound CT states do not preclude efficient radiative recombination.[3]

关键词： Charge-transfer states molecular packing exciton dissociation energy landscape non-radiative voltage losses

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Application of the Shrinking Particle Model for the Evaluation of Molecular Recyclability of PET versus Semi-Aromatic Polyesters

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Open Journal of Physical Chemistry 2024年第2期14卷 21-35页

作者： Jack van Schijndel Sanne de Krom Dennis Molendijk koen van Beurden Amarante Böttger Research Group Biopolymers/Green Chemistry Centre of Expertise Safe & Resilient Society Avans University of Applied Science Breda Netherlands New Materials and Their Applications Centre of Expertise Safe & Resilient Society Avans University of Applied Science Breda Netherlands Department of Materials Science and Engineering Delft University of Technology Delft Netherlands

The molecular recyclability of poly (ethylene terephthalate) (PET) and three semi-aromatic polyesters poly (phloretic acid) (poly-H), poly (dihydroferulic acid) (poly-G), and poly (dihydrosinapinic acid) (poly-S) is evaluated in this study. PET is an extensively used aromatic polyester, and poly-H, poly-G, and poly-S can be considered semi-aromatic poly (lactic acid) modifications. All these polyesters have been depolymerized at neutral pH and by acid- and base-catalyzed hydrolysis at two temperatures, i.e., 50˚C and 80˚C. Base-catalyzed depolymerization of virgin PET leads to an isolated yield of 38% after 48 hours of reaction at 80˚C. Contrary to these results for PET, almost all the monomers of the semi-aromatic polyesters poly-H, poly-G, and poly-S are recovered with isolated yields larger than 90% at the same temperature after 15 minutes in a facile manner. A shrinking particle model used to determine the global kinetics of the base-catalyzed depolymerization showed that the rate rises with increasing temperature. Using the shrinking particle model, the intrinsic reaction rate constants were determined. It has been demonstrated that the rate coefficients of the depolymerization of the semi-aromatic polyesters poly-H, poly-G, and poly-S are between 2 and 3 orders of magnitude higher than those for PET.

关键词： Depolymerization Molecular Recycling Poly-H Poly-G Poly-S PET Circular Polymers

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Solid State Structure and Lyotropic Mesomorphism of Rare-Earth Trisdode cylsulphates in the Water-Ethylene Glycol System

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Journal of Rare Earths 2003年第2期21卷 101-104页

作者： Liesbet Jongen koen Binnemans KatholiekeUniversiteitLeuven KatholiekeUniversiteitLeuven DepartmentofChemistryCelestijnenlaan200FB3001LeuvenBelgiumDepartmentofChemistryCelestijnenlaan200FB3001LeuvenBelgium

The phase behaviour of lanthanide(Ⅲ) dodecylsulphates, Ln(C 12 H 25 SO 4) 3, by thermo optical microscopy using Lawrence penetration technique was investigated. The lyotropic phase behaviour of lanthanide(Ⅲ) dodecylsulphates in ethylene glycol water in mixtures hereof, depends on the composition of the solvent. For pure ethylene glycol and mixtures of ethylene glycol and water three different mesophases are formed, i.e. a lamellar, a cubic and a hexagonal phase, whereas when water is used as solvent no cubic phase is formed. The size of the lanthanide ion has no influence on the mesomorphism of these metallomesogens, although the smaller the lanthanide ion the lower the solubility.

关键词： inorgamic chemistry lanthanides liquid crystals lyotropic mesophases metallomesogens surfactants rare earths

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Transition Modelling with the k-Ω Turbulence Model and an Intermittency Transport Equation

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Journal of Thermal Science 2004年第3期13卷 220-225页

作者： koen LODEFIER Bart MERCI Chris De LANGHE Erik DICK Ghent University Dept. of Flow Heat and Combustion Mechanics Sint-Pietersnieuwstraat 41 B-9000 Gent BelgiumGhent University Dept. of Flow Heat and Combustion Mechanics Sint-Pietersnieuwstraat 41 B-9000 Gent BelgiumGhent University Dept. of Flow Heat and Combustion Mechanics Sint-Pietersnieuwstraat 41 B-9000 Gent BelgiumGhent University Dept. of Flow Heat and Combustion Mechanics Sint-Pietersnieuwstraat 41 B-9000 Gent Belgium

In gas turbine engines, laminar-turbulent transition occurs. However, generally, the turbulence models to describe such transition results in too early and too short transition. Combining a turbulence model with a description of intermittency, i.e. the fraction of time the flow is turbulent during the transition phase, can improve it. By letting grow the intermittency from zero to unity, start and evolution of transition can be imposed. In this paper, a method where a dynamic equation of intermittency combining with a two-equation k-ωturbulence model is described. This intermittency factor is a premultiplicator of the turbulent viscosity computed by the turbulence model. Following a suggestion by Menter et al.[1], the start of transition is computed based on local variables.

关键词： bypass transition intermittency SST turbulence model.

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Application of a k-ε Model to Heat Transfer in Impinging Flows

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Journal of Thermal Science 2004年第1期13卷 62-66页

作者： Bart Merci Chris De Langhe koen Lodefier Erik Dick Ghent University Dept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgiumGhent UniversityDept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgiumGhent UniversityDept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgiumGhent UniversityDept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgium

Local heat transfer is predicted in turbulent axisymmetric jets, impinging onto a flat plate. A non-linear k-e model is used, in which both the constitutive law for the turbulent stresses and the transport equation for the turbulent dissipation rate e have an important contribution in the improved heat transfer predictions. The shape of the Nusselt number profiles, expressing dimensionless heat transfer, as well as the stagnation point value, are well predicted for different distances between the nozzle exit and the plate. Accurate flow field predictions are the basis for good heat transfer predictions. For a fixed Reynolds number, the influence of the nozzle-plate distance is well captured. For a fixed distance, the influence of the Reynolds number is correctly reproduced. Comparisons are made to a low-Reynolds standard k-e model and the v2-f model. A thorough discussion is found in [4]. Only a summary of those results is discussed here, while some new results are also presented.

关键词： local heat transfer impinging jets non-linear k-ε model.

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Modelling overall particle motion in fluidised beds for top-spray coating processes

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Particuology 2013年第5期11卷 490-505页

作者： Mike Vanderroost Frederik Ronsse koen Dewettinck Jan G.Pietersa Department of Biosystems Engineering Ghent UniversityCoupure links 6539000 GhentBelgium Laboratory of Food Technology and Engineering Ghent UniversityCoupure links 6539000 GhentBelgium

A mathematical model predicting the overall particle motion in liquid-sprayed gas-solid fluidised beds has been developed. The proposed model is a superposition of bubble-induced particle motion and particle random walk. The model was validated using experimental particle residence times from literature. Good agreement between experimental and model-predicted residence times was obtained for those cases where atomisation air was absent and on the condition of the inclusion of a so-called ＂dead zone＂. The ＂dead zone＂, being a region of stagnant particles in the annular bottom part of the bed, has also been previously reported in literature. In case atomisation air was present, a less favourable agreement was seen between the model and the experiment. As the atomisatinn air has been shown to significantly alter the ejection distance of particles in the freeboard, recalibration of the ejection height parameter has been demonstrated to obtain an acceptable agreement between model-predicted and experimental data.

关键词： Fluidized bed coatingParticLe residence timeMathematical modelSimulationParticle motion

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