46,766 results on '"Modulus"'
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152. Experimental Study of Viscoelastic and Thermal Analysis of the Amphiphilic Polymer with An Anionic Surfactant and Nano-particles
- Author
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Bakhsh, Allah, Hongbin, Yang, Wanli, Kang, Shaoran, Ren, Shaikh, Azizullah, Jamal ud din, Syed, Liang, Zhang, and Lin, Jia'en, editor
- Published
- 2021
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153. Measurement of Instrumental Texture Profile Analysis (TPA) of Foods
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Rahman, Mohammad Shafiur, Al-Attabi, Zahir Humaid, Al-Habsi, Nasser, Al-Khusaibi, Mohammed, Khan, Mohidus Samad, editor, and Shafiur Rahman, Mohammad, editor
- Published
- 2021
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154. Basic Engineering Concepts and Terminology Underlying Ocular Rigidity
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Boazak, Elizabeth M., Ethier, C. Ross, Pallikaris, Ioannis, editor, Tsilimbaris, Miltiadis K., editor, and Dastiridou, Anna I., editor
- Published
- 2021
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155. Analysis of the Influence of Calculation Parameters on the Design of the Gearbox of a High-Power Wind Turbine
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Francisco Rubio, Carlos Llopis-Albert, and Ana M. Pedrosa
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wind turbine ,gearbox ,calculation parameters ,tooth width ,weight ,modulus ,Mathematics ,QA1-939 - Abstract
As wind turbine power requirements have evolved from the order of kilowatts (kWs) to the order of several megawatts (MWs), wind turbine components have been subjected to more demanding and critical operating conditions. The wind turbine must cope with higher wind loads due to larger blade sizes, which are also time-varying, and, ultimately, higher power levels. One of the challenges in the manufacture of high-power wind turbines lies in the gearbox and consists of achieving ever-greater power density without compromising efficiency, i.e., greater load capacity with lower weight (and production cost) and reduced power losses. Epicyclic geartrains are used to build the gearbox due to various advantages in relation to conventional gear systems, such as higher feasible gear ratios, higher efficiency, compactnesss, and lower weight. In this paper, several epicyclic geartrains with different structures will be analysed to reveal the influence that certain design parameters have on the size and weight of the gearbox components in the selected model and, therefore, of the gearbox itself. For this purpose, the theoretical model of the gearbox will be planned and the influence of the calculation parameters on the gearbox design will be analyzed following ISO 6336. Special emphasis is placed on the influence of the material used; the modulus and tooth width on the size and weight of the gearbox will be observed. Critical stresses are also calculated. The goal is to prepare the theoretical basis for an optimization process subject to geometric, kinematic, and dynamic constraints that will result in a gearbox as compact, energy-dense, and light as possible without compromising the service life of the components.
- Published
- 2023
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156. Analysis of Factors Influencing the Modulus of Hot-Recycled Asphalt Mixture with High RAP
- Author
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Zining Chen, Boying Liu, Decheng Feng, and Gang Li
- Subjects
hot-recycled asphalt mixture ,regenerant ,modulus ,factor analysis ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Generally, the dynamic modulus and bending stiffness modulus are used to evaluate the mechanical properties of asphalt mixture, and they are also used as basic parameters for asphalt mixture design. Therefore, a study was conducted on changes in the dynamic modulus and bending stiffness modulus of hot-recycled asphalt mixture with high levels of reclaimed asphalt pavement (RAP) under the influence of different factors: dosage of regenerant, curing temperature, and curing time. The performance of reclaimed asphalt pavement (RAP) was first evaluated. Then, the hot-recycled asphalt mixture was adjusted and designed in order to conduct modulus experiments, composed of the dynamic modulus test and three-point bending test. Finally, the influencing factors were not only qualitatively but also quantitatively analyzed to clarify the change laws of the mechanical parameters of hot-recycled asphalt mixture. The results showed that the modulus of the recycled asphalt mixture first decreased, then increased, and then decreased with increasing dosage of regenerant. As the curing time or temperature increased, the modulus first decreased and then increased. In terms of the dynamic modulus of the hot-recycled asphalt mixture, the curing time had the greatest impact, followed by dosage of the regenerant and curing temperature. For bending stiffness modulus, the influence of dosage of the regenerant was the greatest, followed by curing time and curing temperature. For the bending stiffness modulus of hot-recycled asphalt mixture, the curing conditions had a greater influence compared with the dynamic modulus.
- Published
- 2023
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157. Numerical and Experimental Analysis of Mechanical Properties in Hybrid Epoxy–Basalt Composites Partially Reinforced with Cellulosic Fillers
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Vijay Chandan, Rajesh Kumar Mishra, Viktor Kolář, Petr Jirků, Miroslav Müller, and Hafsa Jamshaid
- Subjects
hybrid composites ,cellulosic/bio-fillers ,basalt woven fabrics ,mechanical properties ,modulus ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The current work is focused on numerical and experimental studies of woven fabric composites modified by hybridisation with biological (cellulosic) filler materials. The mechanical performance of the composites is characterized under tensile, bending and impact loads and the effect of hybridisation is observed with respect to pure and nonhybrid composites. Numerical models are developed using computational tools to predict mechanical performance under tensile loading. The computational prediction results are compared and validated with relevant experimental results. This research is aimed at understanding the mechanical performance of basalt–epoxy composites partially reinforced with micro-/nano-sized bio-fillers from cellulose and intended for various application areas. Different weave structures, e.g., plain, twill, matt, etc., were investigated with respect to the mechanical properties of the hybrid composites. The effects of hybridizing with cellulose particles and different weave patterns of the basalt fabric are studied. In general, the use of high-strength fibres such as basalt along with cellulosic fillers representing up to 3% of the total weight improves the mechanical performance of the hybrid structures. The thermomechanical performance of the hybrid composites improved significantly by using basalt fabric as well as by addition of 3% weight of cellulosic fillers. Results reveal the advantages of hybridisation and the inclusion of natural cellulosic fillers in the hybrid composite structures. The material developed is suitable for high-end applications in components for construction that demand advanced mechanical and thermomechanical performance. Furthermore, the inclusion of biodegradable fillers fulfills the objectives of sustainable and ecological construction materials.
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- 2023
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158. The modulus of the Fourier transform on a sphere determines 3-dimensional convex polytopes.
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Engel, Konrad and Laasch, Bastian
- Subjects
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FOURIER transforms , *POLYTOPES , *SPHERES , *DIFFRACTION patterns , *X-ray diffraction - Abstract
Let 풫 and P ′ be 3-dimensional convex polytopes in R 3 and S ⊆ R 3 be a non-empty intersection of an open set with a sphere. As a consequence of a somewhat more general result it is proved that 풫 and P ′ coincide up to translation and/or reflection in a point if | ∫ P e - i s ⋅ x dx | = | ∫ P ′ e - i s ⋅ x dx | for all s ∈ S . This can be applied to the field of crystallography regarding the question whether a nanoparticle modelled as a convex polytope is uniquely determined by the intensities of its X-ray diffraction pattern on the Ewald sphere. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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159. Parameters Influence on the Dynamic Properties of Polymer-Matrix Composites Reinforced by Fibres, Particles, and Hybrids.
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Murčinková, Zuzana, Postawa, Przemysław, and Winczek, Jerzy
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FIBROUS composites , *POLYMERIC composites , *FIBERS , *DYNAMIC mechanical analysis , *EPOXY resins , *COMPOSITE materials - Abstract
In this paper, we present an extensive experimental study on the dynamic mechanical properties of composites with polymer matrices, as well as a quantification of the parameters that influence these properties. Polymer-composite matrices make it possible to form any reinforcement arrangement of fibres, particles, and layers, which makes it possible to form composite materials with certain dominant mechanical properties according to the internal arrangement for the application. In this study, we focused on the dynamic properties (i.e., damping parameters, such as the loss factor (tan d), logarithmic decrement (λ), storage modulus (E′), and loss modulus (E″)) of composites with polymer matrices, including parameters such as the fibre material, fabric weaving, fibre orientation, temperature, frequency, particle size, volume of short fibres, and epoxy resin type. If other articles focus on one type of composite and 1–2 parameters, then the benefit of this article lies in our analysis of 8 mentioned parameters in the experimental analysis of 27 different types of composites with polymer matrices. The tested fibre materials were glass, aramid, and carbon; the tested woven fabrics were twill, plain, unidirectional, and satin; the temperature range was from −50 to +230 °C; the frequency was 1 Hz and 10 Hz; the particle size was 0.1–16 mm; the volume percentages of the short fibres were 3, 6, and 12 vol.% of the hybrid polymer composites and the type of polymer matrix. We used the free-damped-vibration method with vibration dynamic signal analysis and the forced-damped vibration of dynamic mechanical thermal analysis for testing. We ranked the parameters that influence the dynamic vibration properties according to the effects. Among sets of results provided in the paper, considering the storage modulus, loss modulus, and loss factor, the best results of the fibre composites were for aramid-fibre-reinforced polymers, regardless of the weave type, with an advantage for unidirectional fabric. The best results of the particle composites were for those with fine filler sizes that incorporated the short fibres. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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160. Production and optimization of the modulus of elasticity, modulus of rupture, and impact energy of GLP-HDPE composite materials using the robust Taguchi technique.
- Author
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Jatau, Sunday, Yawas, Danjuma Saleh, Kuburi, Laminu Shettima, and Samuel, Bassey Okon
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FLEXURAL strength , *HIGH density polyethylene , *WASTE products , *REGRESSION analysis , *ANALYSIS of variance , *MODULUS of elasticity , *COMPOSITE materials - Abstract
With the increase in the use of high-density polyethylene (HDPE) products and the serious long-term hazard they pose to the environment, there has been an increasing need to decrease the release of these materials to the environment as waste. This study sets out to develop and optimize the mechanical properties of the GLP-HDPE composite, a sustainable material made from agro residues (ginger leaf particles (GLP)) and high-density polyethylene waste materials. The Taguchi robust technique, analysis of variance, and regression analysis were employed to optimize, analyze, and model the behavior of the composite materials with respect to the developmental factors of particle size and particle content. The optimum bending modulus of elasticity (MOE), modulus of rupture (MOR), and impact energy (IE) of the developed composites was 2490 MPa, 11.90 MPa, and 4.1 J at a particle size/particle content combination of 710 µm/35%, 520 µm/35%, and 710 µm/45%, respectively. Analysis of variance at 95% confidence level showed that the particle content had a significant effect on the MOE, MOR, and IE of the GLP-HDPE composite with a minimum percentage contribution of 71.61%. Equations for predicting the MOE, MOR, and IE of the composites were developed with good prediction accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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161. Tensile Modulus of Polymer Halloysite Nanotube Systems Containing Filler–Interphase Networks for Biomedical Requests.
- Author
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Zare, Yasser, Rhee, Kyong Yop, and Park, Soo-Jin
- Subjects
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HALLOYSITE , *PERCOLATION , *POLYMER networks - Abstract
To date, there have been a limited number of studies modeling the tensile modulus in the polymer halloysite nanotube (HNT) systems before or after percolation onset. In this paper, an equation for a composite's modulus post-percolation onset was developed for HNT-filled samples including the interphase and HNT network. The dispersed nanoparticles and adjoining interphase part were neglected, because they caused ineffective influences on the stiffness of the system after percolation onset. The developed model reflects the impacts of HNTs' size, interphase depth, percolation onset and the volume shares and moduli of the HNT network and its adjacent interphase on the modulus of HNT-based systems. The impacts of issues on the nanocomposite modulus are defendable, confirming the effectiveness of the developed model. HNT length, interphase depth, HNT concentration, net modulus and net portion directly influenced the stiffness, while the HNT radius and percolation onset had inverse effects. Results show that there was a 142% improvement in the modulus of samples at an interphase depth of 40 nm. Moreover, the stiffness improved by 60% at a net modulus of 200 GPa, but it later exhibited a 180% enhancement at a net modulus of 1000 GPa. In addition, the experimental data for the modulus of numerous composites display fine agreement to the predictions, confirming the validity of the developed model. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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162. Rheological investigation of strain rate and magnetic field on the magnetorheology of zinc ferrite ferrofluid.
- Author
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Ibiyemi, A. Abideen and Yusuf, Gbadebo Taofeek
- Abstract
The major problems disturbing the rheology of magnetic fluid are deformation of magnetic aggregate and destruction of field-induced structure, and this has caused major drawbacks to the rheological systems. The magnitude of the deformation is dependent on the percentage of the strain rate. To curtail the drawback and improve the rheology of the magnetic nanofluid, low strain rate application is required for fluid material testing. Henceforth, we examine the effect of strain rate and magnetic field on the rheological properties of zinc ferrite ferrofluid (FF) using oscillatory sweep test. The rheology of the fluid is examined in the absence and presence of magnetic field at strain amplitude 1%, 10%, 33%, and 100%. The magnitude of the deformation varied as the strain percentage is altered. Low deformation is formed at strain 1% and 10%, this results to the formation of improved and better rheological systemic function, and the rheological function is partially weakened at strain 33%, whereas structural deformation is higher at strain 100%. At strain 100%, the rheological system is largely weakened, but at strain 1%, the rheological system is enhanced. At low strain, high complex magnetoviscosity, low shear stress, low rotating magnetic field, and improved viscoelastic system are formed, but, at high strain application, low complex magnetoviscosity, high shear stress, speedy rotating magnetic field and poor viscoelastic system are formed. A steady-state flow is formed when low relaxation modulus is applied. At high strain, high rotation is formed, and this breaks the rotating magnetic field and destroys the magnetic structure, but at low strain, the rotation of the rotating magnetic field is low, and this protects the aggregates from destruction. The synthesized particles were ultra-sonicated and coated with oleic acid to curtail agglomeration of the particle. The storage modulus (G′) is largely greater than loss modulus, and this established the formation of dominant elastic structure. From TEM analysis, a spherically shaped nanoparticle is formed. The XRD analysis indicates the formation of cubic structure and Fe-phase in trivalent state. The hopping lengths in the tetrahedral site A and octahedral site B are 3.61 nm and 2.94 nm, while the lattice parameters a and c are 8.3298 Å and 13.7501 Å. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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163. Network structural hardening of polypropylene matrix using hybrid of 0D, 1D and 2D carbon-ceramic nanoparticles with enhanced mechanical and thermomechanical properties.
- Author
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Uyor, Uwa O., Popoola, Patricia A. I., and Popoola, Olawale M.
- Subjects
THERMOMECHANICAL properties of metals ,MECHANICAL behavior of materials ,POLYPROPYLENE ,NANOPARTICLES ,BORON nitride ,BARIUM titanate - Abstract
Various dimensional structured inorganic nanoparticles have different ways of improving mechanical properties of polymeric materials. However, there are limited studies on hybridization of different nanoparticles with different dimensional structures for optimal enhancement of mechanical properties of polymer matrix. Therefore, this study combined nanoparticles with 0D (barium titanate [BT]), 1D (carbon nanotubes [C]), and 2D (graphene [G] and boron nitride [BN]) to significantly promote the hardness, elastic modulus, tensile strength/modulus, heat deflection and Vicat softening temperature of polypropylene (PP) nanocomposites. The nanoparticles were surface functionalized to take care of good interfacial interaction with the PP matrix. The nanocomposites were fabricated via melt compounding techniques. Although all the developed nanocomposites showed enhanced mechanical and thermomechanical properties, the ones containing hybrid of carbon and ceramic nanoparticles with different dimensional structures showed superior responses. For instance, optimal hardness, elastic modulus, heat deflection and Vicat softening temperature of about 269.5 MPa, 2.9 GPa, 100.7 °C, and 160 °C were measured for the hybrid PP/3 wt%BNG/3 wt%BTC nanocomposite, which are about 239.4%, 77.7%, 19 °C, and 11 °C higher than that of the pure PP, respectively. The significant enhancement in the measured properties is attributed to effective mechanical interlocking and network structural hardening of the PP matrix. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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164. FDM FABRICATED PLA PARTS: AN EXPERIMENTAL STUDY OF EFFECT OF PROCESS PARAMETERS ON MECHANICAL PROPERTIES UNDER COMPRESSIVE AND FLEXURAL LOADING.
- Author
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Kumar, Shailendra, Teraiya, Soham, and Koriya, Vishal Kumar
- Subjects
COMPRESSION loads ,FLEXURAL strength ,FABRICATION (Manufacturing) ,FUSED deposition modeling ,POLYLACTIC acid ,GENETIC algorithms - Abstract
The present paper describes an experimental investigation on mechanical properties of poly-lactic-acid (PLA) parts under compressive and flexural loading. The PLA parts are fabricated by fused deposition modelling (FDM) technique. In present work, effect of raster angle, raster width and infill density on strength and modulus of parts under compressive and flexural loading is studied. It is found that infill density affects compressive strength and modulus of parts significantly under compressive loading. Compressive properties increase with increase in infill density. Further, it is found that raster width and infill density significantly influence flexural strength and modulus. Flexural properties increase with increase in infill density, and decrease in decrease in raster width. Further, predictive models are developed for responses, and process parameters are optimized using genetic algorithm to maximize the responses. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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165. Short-Term Hydrolytic Degradation of Mechanical Properties of Absorbable Surgical Sutures: A Comparative Study.
- Author
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Szabelski J and Karpiński R
- Abstract
Surgical sutures play a crucial role in wound closure, facilitating the tissue-healing process across various fields of medicine. The objective of this study was to analyse the impact of seasoning time during the initial days/weeks of seasoning in Ringer's solution on the mechanical properties of five commercial absorbable sutures: SafilQuick+
® , Novosyn® , MonosynQuick® , Monosyn® and Monoplus® , each with different absorption periods. The results demonstrated that the SafilQuick+ and MonosynQuick sutures lost strength within 9-12 days, as evidenced by statistically significant changes in tensile strength. In contrast, the Novosyn and Monoplus sutures did not exhibit significant changes in strength during the study period. Statistical analysis confirmed significant differences in the behaviour of the individual sutures, highlighting the importance of selecting appropriate suture material in the context of the specific medical procedure.- Published
- 2024
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166. Nanoporous Aramid Nanofiber Separators with High Modulus and Thermal Stability for Safe Lithium-Ion Batteries.
- Author
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Liu S, Cheng S, Huang C, Han J, Xie J, Zhang P, You Y, Chen W, and Fu Z
- Abstract
Developing high-safety separators is a promising strategy to prevent thermal runaway in lithium-ion batteries (LIBs), which stems from the low melting temperatures and inadequate modulus of commercial polyolefin separators. However, achieving high modulus and thermal stability, along with uniform nanopores in these separators, poses significant challenges. Herein, the study presents ultrathin nanoporous aramid nanofiber (ANF) separators with high modulus and excellent thermal stability, enhancing the safety of LIBs. These separators are produced using a microfluidic-based continuous printing strategy, where the flow thickness can be meticulously controlled at the micrometer scale. This method allows for the continuous fabrication of nanoporous ANF separators with thicknesses ranging from 1.6 ± 0.1 µm to 2.7 ± 0.1 µm. Thanks to the double-side solvent diffusion, the separators exhibit controllably uniform pore sizes with a narrow distribution, spanning from 40 ± 5 nm to 105 ± 9 nm, and a high modulus of 3.3 ± 0.5 GPa. These nanoporous ANF separators effectively inhibit lithium dendrite formation, resulting in a high-capacity retention rate for the LIBs (80% after 240 cycles). Most notably, their robust structural and mechanical stability at elevated temperatures significantly enhances LIB safety under transient thermal abuse conditions, thus addressing critical safety concerns associated with LIBs., (© 2024 Wiley‐VCH GmbH.)
- Published
- 2024
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167. Cross-linking manipulation of waterborne biodegradable polyurethane for constructing mechanically adaptable tissue engineering scaffolds.
- Author
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Sheng N, Lin W, Lin J, Feng Y, Wang Y, He X, He Y, Liang R, Li Z, Li J, Luo F, and Tan H
- Abstract
Mechanical adaptation of tissue engineering scaffolds is critically important since natural tissue regeneration is highly regulated by mechanical signals. Herein, we report a facile and convenient strategy to tune the modulus of waterborne biodegradable polyurethanes (WBPU) via cross-linking manipulation of phase separation and water infiltration for constructing mechanically adaptable tissue engineering scaffolds. Amorphous aliphatic polycarbonate and trifunctional trimethylolpropane were introduced to polycaprolactone-based WBPUs to interrupt interchain hydrogen bonds in the polymer segments and suppress microphase separation, inhibiting the crystallization process and enhancing covalent cross-linking. Intriguingly, as the crosslinking density of WBPU increases and the extent of microphase separation decreases, the material exhibits a surprisingly soft modulus and enhanced water infiltration. Based on this strategy, we constructed WBPU scaffolds with a tunable modulus to adapt various cells for tissue regeneration and regulate the immune response. As a representative application of brain tissue regeneration model in vivo, it was demonstrated that the mechanically adaptable WBPU scaffolds can guide the migration and differentiation of endogenous neural progenitor cells into mature neurons and neuronal neurites and regulate immunostimulation with low inflammation. Therefore, the proposed strategy of tuning the modulus of WBPU can inspire the development of novel mechanically adaptable biomaterials, which has very broad application value., (© The Author(s) 2024. Published by Oxford University Press.)
- Published
- 2024
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168. Investigation into a practical approach and application of cotton fiber elongation
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Delhom, Christopher D., Wanjura, John D., Pelletier, Mathew G., Holt, Gregory A., and Hequet, Eric F.
- Published
- 2023
- Full Text
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169. Impact of aliovalent ions doping on structural and electrical characteristics of YMnO3 ceramic
- Author
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Shukla, Jyoti, Saxena, Pallavi, Joshi, Prabhav, Joshi, Prachi, and Mishra, Ashutosh
- Published
- 2023
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170. Introduction to Liquid Crystalline Polymers
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Banerjee, Soma, Kar, Kamal K., Kar, Kamal K., Editor-in-Chief, Zhu, Lei, editor, and Li, Christopher Y., editor
- Published
- 2020
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171. A New Rabin-Type Cryptosystem with Modulus
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Mooney, Digby, Batten, Lynn M., Zhang, Leo Yu, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Batina, Lejla, editor, and Li, Gang, editor
- Published
- 2020
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172. Pressuremeter Test in Municipal Solid Waste for Coastal Reclamation Project
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Santoso, Petrus Chanel S., Sugianto, Andy, Rahardjo, Paulus P., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Duc Long, Phung, editor, and Dung, Nguyen Tien, editor
- Published
- 2020
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173. Numerical Study on the Feasibility of Flexible Runway Pavement to Resist Impact Loading
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Ali, S., Liu, X., Fawzia, S., Thambiratnam, D., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Ho, Johnny C.M., editor, and Kitipornchai, Sritawat, editor
- Published
- 2020
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174. Preliminary Study on the Mechanical Properties of an Asphalt Mixture Containing RAR Modifiers
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Plati, Christina, Cliatt, Brad, Loizos, Andreas, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Pasetto, Marco, editor, Partl, Manfred N., editor, and Tebaldi, Gabriele, editor
- Published
- 2020
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175. A Review on Tensile Properties of Epoxy Polymer Matrix Nanocomposites by Pure and Hybrid Nanosilica Reinforcements
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Sarode, Pratik, Bhombe, Saurabh, Raskar, Swapnil, Raut, Ramnath, Bhalwankar, Manoj, Pawar, Prashant M., editor, Ronge, Babruvahan P., editor, Balasubramaniam, R., editor, Vibhute, Anup S., editor, and Apte, Sulabha S., editor
- Published
- 2020
- Full Text
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176. Investigations of Structural, Magnetic, and Electrochemical Properties of NiFe2O4 Nanoparticles as Electrode Materials for Supercapacitor Applications
- Author
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Shalendra Kumar, Faheem Ahmed, Nagih M. Shaalan, Nishat Arshi, Saurabh Dalela, and Keun Hwa Chae
- Subjects
NiFe2O4 nanoparticles ,dielectric ,modulus ,AC conductivity ,ferromagnetism ,supercapacitor ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Magnetic nanoparticles of NiFe2O4 were successfully prepared by utilizing the sol–gel techniques. The prepared samples were investigated through various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), dielectric spectroscopy, DC magnetization and electrochemical measurements. XRD data analysed using Rietveld refinement procedure inferred that NiFe2O4 nanoparticles displayed a single-phase nature with face-centred cubic crystallinity with space group Fd-3m. Average crystallite size estimated using the XRD patterns was observed to be ~10 nm. The ring pattern observed in the selected area electron diffraction pattern (SAED) also confirmed the single-phase formation in NiFe2O4 nanoparticles. TEM micrographs confirmed the uniformly distributed nanoparticles with spherical shape and an average particle size of 9.7 nm. Raman spectroscopy showed characteristic bands corresponding to NiFe2O4 with a shift of the A1g mode, which may be due to possible development of oxygen vacancies. Dielectric constant, measured at different temperatures, increased with temperature and decreased with increase in frequency at all temperatures. The Havrilliak–Negami model used to study the dielectric spectroscopy indicated that a NiFe2O4 nanoparticles display non-Debye type relaxation. Jonscher’s power law was utilized for the calculation of the exponent and DC conductivity. The exponent values clearly demonstrated the non-ohmic behaviour of NiFe2O4 nanoparticles. The dielectric constant of the nanoparticles was found to be >300, showing a normal dispersive behaviour. AC conductivity showed an increase with the rise in temperature with the highest value of 3.4 × 10−9 S/cm at 323 K. The M-H curves revealed the ferromagnetic behaviour of a NiFe2O4 nanoparticle. The ZFC and FC studies suggested a blocking temperature of ~64 K. The saturation of magnetization determined using the law of approach to saturation was ~61.4 emu/g at 10 K, corresponding to the magnetic anisotropy ~2.9 × 104 erg/cm3. Electrochemical studies showed that a specific capacitance of ~600 F g−1 was observed from the cyclic voltammetry and galvanostatic charge–discharge, which suggested its utilization as a potential electrode for supercapacitor applications.
- Published
- 2023
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177. Effective Elastic Modulus of Wavy Single-Wall Carbon Nanotubes
- Author
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Chensong Dong
- Subjects
carbon nanotube (CNT) ,modulus ,waviness ,Monte Carlo simulation ,Organic chemistry ,QD241-441 - Abstract
A simple method for determining the effective elastic modulus of wavy single-wall carbon nanotubes (SWCNTs) is presented in this paper. The effective modulus of curved SWCNTs is derived using Castigliano’s theorem. The effect of curvature on the effective modulus is studied. This method is verified by finite element analysis (FEA). The distributions of effective moduli are studied by Monte Carlo simulation. The effective modulus of a general wavy SWCNT is derived by considering the SWCNT as a number of curved SWCNT sections.
- Published
- 2023
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178. Hardness, Modulus, and Refractive Index of Plasma-Assisted Atomic-Layer-Deposited Hafnium Oxide Thin Films Doped with Aluminum Oxide
- Author
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Mikk Kull, Helle-Mai Piirsoo, Aivar Tarre, Hugo Mändar, Aile Tamm, and Taivo Jõgiaas
- Subjects
atomic layer deposition ,thin film ,mechanical properties ,nanoindentation ,hardness ,modulus ,Chemistry ,QD1-999 - Abstract
Coatings with tunable refractive index and high mechanical resilience are useful in optical systems. In this work, thin films of HfO2 doped with Al2O3 were deposited on silicon at 300 °C by using plasma-enhanced atomic layer deposition (PE-ALD). The mainly amorphous 60–80 nm thick films consisted Al in the range of 2 to 26 at.%. The refractive indexes varied from 1.69 to 2.08 at the wavelength of 632 nm, and they consistently depended on the composition. The differences were higher in the UV spectral region. At the same time, the hardness of the films was from 12–15 GPa; the modulus was in the range of 160–180 GPa; and the mechanical properties did not have a good correlation with the deposited compositions. The deposition conditions, element contents, and refractive indexes at respective wavelengths were correlated. The results indicated that it is possible to tune optical properties and retain mechanical properties of atomic layer-deposited thin films of HfO2 with Al2O3 as doping oxide. Such films could be used as mechanically resilient and optically tunable coatings in, for instance, micro- or nano-electromechanical systems or transparent displays.
- Published
- 2023
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179. Effects of Aging on Multiscale Mechanistic Properties of Asphalt Binders
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Roy, Sumon and Hossain, Zahid
- Published
- 2023
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180. Long-Term Assessment of Contemporary Ion-Releasing Restorative Dental Materials.
- Author
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Marovic, Danijela, Par, Matej, Posavec, Karlo, Marić, Ivana, Štajdohar, Dominik, Muradbegović, Alen, Tauböck, Tobias T., Attin, Thomas, and Tarle, Zrinka
- Subjects
- *
DENTAL materials , *FLEXURAL modulus , *FLEXURAL strength , *MATERIALS testing , *SOLUBILITY - Abstract
The objective was to evaluate new commercially available ion-releasing restorative materials and compare them to established anti-cariogenic materials. Four materials were tested: alkasite Cention (Ivoclar Vivadent) in self-cure or light-cure mode, giomer Beautifil II (Shofu), conventional glass-ionomer Fuji IX (GC), and resin composite Tetric EvoCeram (Ivoclar Vivadent) as a control. Flexural strength, flexural modulus, and Weibull modulus were measured one day, three months, and after three months with accelerated aging in ethanol. Water sorption and solubility were evaluated for up to one year. Degree of conversion was measured during 120 min for self-cured and light-cured Cention. In this study, Beautifil II was the ion-releasing material with the highest flexural strength and modulus and with the best resistance to aging. Alkasite Cention showed superior mechanical properties to Fuji IX. Weibull analysis showed that the glass-ionomer had the least reliable distribution of mechanical properties with the highest water sorption. The solubility of self-cured alkasite exceeded the permissible values according to ISO 4049. Degree of conversion of light-cured Cention was higher than in self-cure mode. The use of alkasite Cention is recommended only in the light-cure mode. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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- View/download PDF
181. Finite element analysis of trabecular bone microstructure using CT imaging and continuum mechanical modeling.
- Author
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Guha, Indranil, Zhang, Xiaoliu, Rajapakse, Chamith S., Chang, Gregory, and Saha, Punam K.
- Subjects
- *
COMPUTED tomography , *FINITE element method , *POISSON'S ratio , *MAGNETIC resonance imaging , *MECHANICAL models , *BONE densitometry , *CANCELLOUS bone - Abstract
Purpose: Osteoporosis is a bone disease associated with enhanced bone loss, microstructural degeneration, and fracture‐risk. Finite element (FE) modeling is used to estimate trabecular bone (Tb) modulus from high‐resolution three‐dimensional (3‐D) imaging modalities including micro‐computed tomography (CT), magnetic resonance imaging (MRI), and high‐resolution peripheral quantitative CT (HR‐pQCT). This paper validates an application of voxel‐based continuum finite element analysis (FEA) to predict Tb modulus from clinical CT imaging under a condition similar to in vivo imaging by comparing with measures derived by micro‐CT and experimental approaches. Method: Voxel‐based continuum FEA methods for CT imaging were implemented using linear and nonlinear models and applied on distal tibial scans under a condition similar to in vivo imaging. First, tibial axis in a CT scan was aligned with the coordinate z‐axis at 150 μm isotropic voxels. FEA was applied on an upright cylindrical volume of interests (VOI) with its axis coinciding with the tibial bone axis. Voxel volume, edge, and vertex elements and their connectivity were defined as per the isotropic image grid. A calibration phantom was used to calibrate CT numbers in Hounsfield unit to bone mineral density (BMD) values, which was then converted into calcium hydroxyapatite (CHA) density. Mechanical properties at each voxel volume element was defined using its ash‐density defined on CT‐derived CHA density. For FEA, the bottom surface of the cylindrical VOI was fixed and a constant displacement was applied along the z‐direction at each vertex element on the top surface to simulate a physical axial compressive loading condition. Finally, a Poisson's ratio of 0.3 was applied, and Tb modulus (MPa) was computed as the ratio of average von Mises stress (MPa) of volume elements on the top surface and the applied displacement. FEA parameters including mesh element size, substep number, and different tolerance values were optimized. Results: CT‐derived Tb modulus values using continuum FEA showed high linear correlation with the micro‐CT‐derived reference values (r ∈ [0.87 0.90]) as well as experimentally measured values (r ∈ [0.80 0.87]). Linear correlation of computed modulus with their reference values using continuum FEA with linear modeling was comparable with that obtained by nonlinear modeling. Nonlinear continuum FEA‐based modulus values (mean of 1087.2 MPa) showed greater difference from their reference values (mean of 1498.9 MPa using micro‐CT‐based FEA) as compared with linear continuum methods. High repeat CT scan reproducibility (intra‐class correlation [ICC] = 0.98) was observed for computed modulus values using both linear and nonlinear continuum FEA. It was observed that high stress regions coincide with Tb microstructure as fuzzily characterized by BMD values. Distributions of von Mises stress over Tb microstructure and marrow regions were significantly different (p < 10–8). Conclusion: Voxel‐based continuum FEA offers surrogate measures of Tb modulus from CT imaging under a condition similar to in vivo imaging that alleviates the need for segmentation of Tb and marrow regions, while accounting for bone distribution at the microstructural level. This relaxation of binary segmentation will extend the scope of FEA application to assess mechanical properties of bone microstructure at relatively low‐resolution imaging. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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182. Is there any predictive value of testicular shear wave elastic modulus in testicular functions for varicocele patients?
- Author
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Mulati, Yelisudan, Li, Xiaodong, Maimaitiming, Abulaiti, Apizi, Aireti, and Wang, Yujie
- Subjects
- *
SHEAR waves , *TESTIS physiology , *ELASTIC waves , *ELASTIC modulus , *VARICOCELE - Abstract
This study aimed at searching the predictive values of testicular shear wave elastic modulus in testicular functions for varicocele patients. This was a prospective case–control study. We divided the participants into two groups: varicocele group and control group, the latter recruited men with normal physical examination, testicular ultrasound, semen and endocrine results. A total of 97 participants were enrolled: 67 patients in varicocele group, 30 participants in control group. There were statistical differences in left testicular shear wave elastic modulus, left testicular volume, testicular atrophy index, total sperm count, sperm concentration, sperm viability and testosterone between the two groups, between different grades in varicocele group, between different periods in varicocele group. Left testicular shear wave elastic modulus was inversely correlated with total sperm count, sperm concentration, sperm viability and testosterone. Left testicular shear wave elastic modulus cut‐off was calculated as 5.235, 5.130, 4.640 and 5.310 Kpa using ROC curve according to the abnormalities of total sperm count, sperm concentration, sperm viability and testosterone. When the left testicular shear wave elastic modulus was higher than these values, the corresponding parameter was more likely to be abnormal. Testicular shear wave elastic modulus has predictive values in testicular functions for varicocele patients. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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183. Micro and macro analysis of physicochemical properties of bio-based semi-aromatic high temperature polyamide PA5T/56.
- Author
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Meng, Chihan and Liu, Xiucai
- Abstract
In this paper, bio-based semi-aromatic high-temperature polyamide PA5T/56 was synthesized from bio-based monomer glutamine. The micro and macro physicochemical properties of PA5T/56 were studied by Materials Studio software, Universal Testing Machine and Impact Testing Machine and other software and instruments, and the effect of PA5T content on its properties was explored. The results showed that the Poisson's ratio and modulus of PA56 molecule were the largest, PA5T molecule was the smallest, and PA56T molecule was between the two, indicated that the addition of PA5T molecule enhances the overall mechanical properties; With the increase in PA5T content, the tensile strength and bending strength of PA5T/56 increases, while the elongation at break and impact strength decreases, the density of PA5T/56 increases first and then decreases, and the oil absorption rate and water absorption rate of PA5T/56 decrease gradually; Moreover, PA5T/56 has excellent solvent resistance, it is insoluble in conventional organic solvents and only soluble in concentrated sulfuric acid and trifluoroacetic acid; With the extension of soaking time, the tensile strength and bending strength of PA5T/56 decrease, while the impact strength of PA5T/56 increases first and then decreases. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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184. Parametric investigation for mechanical properties of tetra‐anti‐chiral auxetic structures of polymer under compressive loading.
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Teraiya, Soham, Vyavahare, Swapnil, and Kumar, Shailendra
- Subjects
AUXETIC materials ,COMPRESSION loads ,POLYMER structure ,SCANNING electron microscopes ,ACRYLONITRILE butadiene styrene resins ,COMPRESSIVE strength ,PROCESS optimization - Abstract
In the present work, an experimental investigation is performed to study the influence of process parameters on mechanical properties of tetra‐anti‐chiral auxetic structures manufactured by material extrusion (ME) technique of additive manufacturing (AM). Process parameters namely layer height, print speed, and print temperature are considered, while responses are compressive strength (σ), modulus (E), and specific energy absorption (SEA). Specimens of acrylonitrile‐butadiene‐styrene (ABS) polymer are fabricated and then tested under compressive loading. From the experimental results, it is observed that all process parameters significantly influence the mechanical properties of the structure. Scanning electron microscope (SEM) is used to study microstructural defects of the tested specimen. To maximize the responses, optimization of process parameter is performed using desirability function approach. Regressive models are developed to predict the mechanical properties. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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185. Advanced Kolarik model for the modulus of a nanocomposite system reinforced by halloysite nanotubes and interphase zone.
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Zare, Yasser and Rhee, Kyong Yop
- Subjects
- *
HALLOYSITE , *NANOTUBES , *NANOCOMPOSITE materials , *DENSITY matrices - Abstract
In the current article, Kolarik model is progressed for the tensile modulus of a polymeric system containing dispersed halloysite nanotubes (HNT) and adjacent interphase section. The progressive model correlates the nanocomposite's modulus to HNT concentration (volume fraction and weight percentage), the extents of HNT and nearby interphase section in addition to the densities of polymer medium and HNT. The productions of the progressive model are linked to the tentative results and the influences of all variables on the modulus of system are justified. The modulus of system reduces as HNT radius increases, but HNT weight percentage directly controls the nanocomposite's modulus. The modulus of samples maximizes by 47% by the deepest interphase section of 20 nm establishing a straight link among nanocomposite's modulus and interphase thickness. The increment of polymer matrix density improves the modulus of samples, but there is an opposite relation between the modulus of system and HNT density. Furthermore, the calculations exactly match to the experimental facts of numerous examples representing the accurateness of the progressed model. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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186. Blending for Achieving Theoretical Mechanical and Electrical Property Enhancement in Polyacrylonitrile/SWNT Materials.
- Author
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Li, Heng, Doyle, Conor M., and Minus, Marilyn L.
- Subjects
HYBRID materials ,POLYMER blends ,MECHANICAL properties of condensed matter ,ELECTRIC conductivity ,CARBON nanotubes ,MANUFACTURING processes - Abstract
Filtration based processing of nanotube and polymer-nanotube dispersions is used to create polymer and nano-filler hybrid materials. The composite morphology consists of two layers: (1) a region where polymer chains have direct matrix interaction with the nano-fillers and (2) a nano-filler rich region excluded from matrix interactions. The experimental work here demonstrates the processing of this hybrid material using polyacrylonitrile (PAN) and single-wall carbon nanotubes (SWNT) at various PAN/SWNT weight concentrations. Mechanical analyses were performed to evaluate effective contributions from the SWNT in each of the defined layers. The region of high matrix-filler interactions exhibits blending behavior with material properties following suit. As a result, mechanical performance is consistent and begins to exceed theoretical predictions derived from Halpin–Tsai calculations. Tensile strength and modulus reached values as high as 60 MPa and 7.7 GPa, respectively, surpassing the performance of neat nano-filler (36 MPa, 3.9 GPa) and neat polymer matrix (44 MPa, 2.0 GPa) films. Additionally, the measurement of electrical properties shows that the blended polymer-SWNT region exhibits conductivity comparable to the filler. The results of this work suggest that blending polymers and nano-fillers is possible and may facilitate the production of materials with comparatively high mechanical performance and electrical conductivities. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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- View/download PDF
187. Effect of sample thickness on tensile properties of polyethylene.
- Author
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WEN Yuan, MAO Xianpeng, and XU Kejie
- Subjects
POLYETHYLENE ,PLASTICS ,TENSILE tests ,INVESTIGATION reports ,PLANT fibers ,PRODUCT design - Abstract
This paper reported an investigation on the effect of sample thickness on tensile properties of polyethylene (PE). Through the analysis of tensile tests of PE samples with different thickness, the thickness could generate a great influence on the strength, strain and tensile modulus of PE. However, there was no effect on the yield absorption energy per unit area. In the current design of plastic products, there have been hidden dangers with the tensile properties of PE materials and the thickness of products as two independent parameters. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
188. Cyclic behavior of cement-stabilized sabkha soil.
- Author
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Alshenawy, Abdulhafiz Omar, Alsanabani, Naif Mohammed, and Alnuaim, Ahmed Mohamed
- Abstract
Cement stabilization is one of the chemical stabilization techniques carried out to improve sabkha soil engineering properties. Cement can be mixed with sabkha at natural water content. However, there is a lack of information concerning the dynamic properties of cemented sabkha. Therefore, this study's primary purpose is to determine the dynamic properties of cemented sabkha, at cement content of 5% and 10%, which satisfied static requirements and compare it with untreated sabkha in literature. The tests were carried out using the cyclic triaxial test at several effective stresses and cyclic stress ratios (CSR). The averages of shear modulus of cemented sabkha of 5% cement are 38, 32, and 21 MPa for cyclic stress ratio of 0.15, 0.35, and 0.65, respectively; they are 85, 45, and 43 MPa for 10% cement. Furthermore, the averages of damping of 5% cement are 0.03, 0.016, and 0.014 for CSR of 0.15, 0.35, and 0.65, respectively; they are 0.027, 0.012, and 0.01 for 10% cement. The results indicate that the increasing cement content to sabkha from 5 to 10% decreases the shear strain ratio by 0.05, 0.04, and 0.22 for CSR of 0.15, 0.35, and 0.65, respectively. For CSR of 0.15, the change in cement content from 5 to 10% leads to increased shear modulus by 1.4 to 3 times of shear modulus of untreated sabkha; the shear modulus ratio of cemented sabkha to shear modulus to sabkha increases with the increasing number of cycles. The cement content of 5 and 10% leads to a decrease in the normalized damping ratio of cemented sabkha to damping ratio of sabkha with a range from 0.55 to 0.85. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
189. Robotic automated fiber placement of carbon fiber towpregs.
- Author
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Forcellese, A., Mancia, T., Russo, A.C., Simoncini, M., and Vita, A.
- Subjects
CARBON fibers ,LAMINATED materials ,TENSILE strength ,SURFACE topography ,ELASTIC modulus ,SCANNING electron microscopy - Abstract
Robotic Automated Fiber Placement (R-AFP) technology was developed to manufacture composite laminates by placing carbon fiber thermoset towpregs, obtained by impregnating 12 K high-strength grade carbon fibers in an epoxy resin system. In order to avoid placement induced defects, a thermographic scanning technique was implemented for on-line quality monitoring of the R-AFP process. The thermal analysis proved to be an effective and quick approach for the real-time detection of deposition defects generated during. The R-AFP process was performed by applying a constant pressure through the compaction roller; different pressure values were investigated. The effect of the resin weight fraction and compaction pressure on the mechanical properties applied by the deposition head during R-AFP of cross-ply laminates was studied. The reduction of the tensile strength and the increase of the elastic modulus with decreasing pressure of the compaction roller was observed. Furthermore, the values of ultimate tensile strength and elastic modulus decrease as the resin content increases. Finally, the three-dimensional topography of surface fracture of tensile samples was investigated by means of the optical and scanning electron microscopy. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
190. Exploitation of static and dynamic methods for the analysis of the mechanical nanoproperties of polymethylmetacrylate by indentation
- Author
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Benaissa Soufiane, Habibi Samir, Semsoum Djameleddine, Merzouk Hassen, Mezough Abdelnour, Boutabout B�nali, and Montagne Alex
- Subjects
modulus ,hardness ,nanometer scale ,low indentation depths ,indentation size effect ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
Elaborating an instrumented nanoindentation is to exercise non-destructive tests to be applied to volumes of polymethylmetacrylate (PMMA) materials in miniature. This work focuses on factors that explain the trends variation of mechanical properties like Young's modulus (E), contact hardness (H) and indentation force (P). The evolution of E and H with depth (h) and P shows a 2.77 nm inflection point at low penetrations, separating two zones: the first increasing and the second decreasing. This is respectively explained by the surface hardening induced by preparing the material surface, and the existence of a surface hardness gradient denoted by an indentation size effect (ISE) observed at very low depths. Moreover, In addition, a critical penetration depth of 9.71 nm below which the surface effect dominates the variation of the penetrating load is detected. E and H results differences between dynamic and static modes are 8.46% and 6.44% inducing an overestimation of 35 MPa in E value, and an underestimation of 1.23 MPa in H value. This tends to affect the expected nanoscale precision of the indentation to determine the nanomechanical properties of PMMA.
- Published
- 2021
- Full Text
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191. Biomechanical relationships between the corneal endothelium and Descemet's membrane
- Author
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Ali, Maryam, Raghunathan, VijayKrishna, Li, Jennifer Y, Murphy, Christopher J, and Thomasy, Sara M
- Subjects
Biomedical and Clinical Sciences ,Ophthalmology and Optometry ,Eye Disease and Disorders of Vision ,2.1 Biological and endogenous factors ,Eye ,Corneal Topography ,Descemet Membrane ,Endothelium ,Corneal ,Fuchs' Endothelial Dystrophy ,Humans ,Mechanotransduction ,Cellular ,Endothelium ,Descemet's membrane ,Mechanotransduction ,Extracellular matrix ,Topography ,Modulus ,Fuchs' corneal endothelial dystrophy ,Medical Biochemistry and Metabolomics ,Neurosciences ,Opthalmology and Optometry ,Ophthalmology & Optometry ,Ophthalmology and optometry - Abstract
The posterior face of the cornea consists of the corneal endothelium, a monolayer of cuboidal cells that secrete and attach to Descemet's membrane, an exaggerated basement membrane. Dysfunction of the endothelium compromises the barrier and pump functions of this layer that maintain corneal deturgesence. A large number of corneal endothelial dystrophies feature irregularities in Descemet's membrane, suggesting that cells create and respond to the biophysical signals offered by their underlying matrix. This review provides an overview of the bidirectional relationship between Descemet's membrane and the corneal endothelium. Several experimental methods have characterized a richly topographic and compliant biophysical microenvironment presented by the posterior surface of Descemet's membrane, as well as the ultrastructure and composition of the membrane as it builds during a lifetime. We highlight the signaling pathways involved in the mechanotransduction of biophysical cues that influence cell behavior. We present the specific example of Fuchs' corneal endothelial dystrophy as a condition in which a dysregulated Descemet's membrane may influence the progression of disease. Finally, we discuss some disease models and regenerative strategies that may facilitate improved treatments for corneal dystrophies.
- Published
- 2016
192. Effect of Al substitution on the magnetic, optical and electronic properties of KBiFe2O5 brownmillerite.
- Author
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Sahoo, Payala, Ray, Sujata Kumari, Pati, Anupama, Sahoo, A.K., Chakravarty, Sujay, and Dash, S.
- Subjects
- *
OPTICAL properties , *MAGNETIC anomalies , *MAGNETIC moments , *BAND gaps , *COOLING curves , *POLARONS - Abstract
We reveal the influence of non-magnetic Al3+ ion on magnetic, optical and electronic properties of KBiFe 2 O 5. Al doped KBiFe 2-x Al x O 5 (x = 0, 0.2, 0.4) are synthesized by citrate combustion method. All the samples are found to be crystalized in monoclinic structure with P 2/ c space group. With Al doping, the grain size of the samples is reduced however, Fe ions maintain its +3 state. A mere difference in the low temperature zero field cooling and field cooling curve discards the multiple magnetic phases at low temperature, however, with Al, an improved magnetic moment is detected in the magnetic isotherms. A schematic model is adopted to explain the enhanced magnetization. Furthermore, the magnetic anomaly around the dielectric transition (760–780 K) depicts an existence of magnetoelectric coupling in all the samples. The optical band gap is reduced from 1.73 eV to 1.69 eV with Al doping. Extensive dielectric and electric modulus analysis is carried out to explore the conduction as well as relaxation process in the parent and Al doped system. The activation energy estimated from the electric modulus is (0.412 ± 0.021) eV for x = 0 and (0.370 ± 0.025) eV for x = 0.2 respectively but surprisingly, Al doping with x = 0.4 shows a completely different relaxation mechanism. Moreover, the frequency dependent ac conductivity is also explained and agrees well with the electric modulus data. Magnetic characterization of Al doped KBiFe 2 O 5. [Display omitted] • We prepare the Al doped KBiFe 2 O 5 through citrate combustion method. • Low band gap of ∼1.73 eV–1.69 eV, is favorable for solar cell and photocatalyst. • Al improves the magnetic moment with an existence of magnetoelectric coupling. • Conduction process is mainly governed by CBH and polaron hopping model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
193. Structural, dielectric and ac ionic conductivity of Li4FeSbO6 oxide.
- Author
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Doughri, D., Mehdaoui, B., Fakhreddine, R., and El Bouari, A.
- Subjects
- *
DIELECTRIC properties , *DIELECTRICS , *IONIC conductivity , *ULTRAVIOLET-visible spectroscopy , *IMPEDANCE spectroscopy , *ACTIVATION energy - Abstract
The Li 4 FeSbO 6 compound was prepared by solid state route at high temperature. It crystallizes in the monoclinic system with space group C 2/ m and cell parameters a = 5.1711(2) Å, b = 8.9406(3) Å, c = 5.1687(2). The purity and morphology were investigated, the sample is formed of aggregates of different sizes and each aggregate consists of particles widely dispersed in size and shape. Ultraviolet–visible spectroscopy was used to determine information about electronic transitions. Three absorption bands were observed and attributed to spin-forbidden electronic transitions of Fe3+(d5) in an octahedral field. The band gap obtained from Ultraviolet–visible spectroscopy is about 2.01 eV. The dielectric properties were investigated in the frequency range of 10 Hz to 1 MHz at different temperatures from 303 K to 673 K. The impedance spectroscopy confirmed the grains and grain boundaries effects. The complex permittivity was found to have two contributions, one dipolar and the other conductive. The relaxation time of the dipolar contribution matches well with the Maxwell-Wagner relaxation time, indicating that the sample is electrically inhomogeneous. The ionic conductivity of Li+ ions was attributed to the bulk resistance of Li 4 FeSbO 6. The conduction mechanism in the bulk material Li 4 FeSbO 6 was studied with Jonscher's law which confirmed the presence of conductive pathways in the material. The hopping frequency was evaluated from the modulus, the activation energy obtained is E a = 0.57(3) eV, similar to that determined from the impedance analyzes. The conduction pathways of Li+ ions and the corresponding migration barrier energy values were calculated by the Bond Valence Path Analyzer. The results suggest that Li+ ions mainly diffuse along a 3D path with a migration barrier of 0.57 eV, which is in perfect agreement with the activation energy determined from the conductivity of bulk Li 4 FeSbO 6. [Display omitted] • Ionic conductivity is determined by combination of permittivity, impedance and modulus. • Permittivity analysis reveals both dipolar and conductive contributions. • Relaxation time of the dipolar component aligns with Maxwell-Wagner relaxation. • Grain and grain boundary effects are confirmed by impedance and modulus spectroscopy. • Bulk conductivity activation energy matches the migration barrier for Li ions along a 3D path. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
194. Temperature-Dependent electrical and dielectric characteristics of lead germanate Pb5Ge1.5Sn1.5O11.
- Author
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Aryam Behera, Swayam, Khatua, Deeptimayee, Kumar Singh, Rajesh, Choudhary, R.N.P., and Ganga Raju Achary, P.
- Subjects
- *
DIELECTRICS , *DIELECTRIC properties , *ELECTRICAL resistivity , *THERMISTORS , *PERMITTIVITY , *REFLECTANCE spectroscopy - Abstract
[Display omitted] • Improved ε r and ac-conductivity of Sn-modified lead germanate. • Temperature-dependent dielectric and electrical properties. • Decreased E a and revealed conduction mechanism of PGSO at higher temperatures. • NTCR behavior of PGSO for high-sensitivity thermistors and sensors. • Thermistor constant (β) of 1662 K in 250 °C-300 °C. A solid-state reaction was used to synthesize the tin modified lead germanate: Pb 5 Ge 1.5 Sn 1.5 O 11 (PGSO). The composition was modified to enhance its dielectric and electrical properties. The PGSO sample was characterized by various analytical techniques, such as XRD for structural analysis and FTIR for additional structural information. The surface morphology and features of PGSO were examined by SEM, while its band gap was determined by UV–Visible-Diffuse Reflectance Spectroscopy absorbance spectra. The impedance, dielectric behaviour, AC conductivity, activation energy, and modulus of PGSO were also studied. The temperature dependence of the dielectric constant and AC conductivity showed an increase with increasing temperature. The electrical resistivity (R) decreased as the temperature increased from 100 °C to 300 °C, exhibiting a NTCR behaviour for PGSO sample, which could be applied as a high temperature thermistor and sensor, and could be used to fabricate a high sensitivity, low-cost thermistor. The circuit parameters such as bulk resistance (R b), frequency factor (n), and bulk capacitance (C b) were determined by fitting the Nyquist plot using an equivalent circuit (CQR)(CR). [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
195. Formulation of conductivity, electric modulus and dielectric behaviour of calcium bismuth borovanadate glasses with varying temperature and frequency.
- Author
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Rani, Asha, Parmar, Rajesh, and Kundu, R.S.
- Subjects
- *
DIELECTRIC relaxation , *BISMUTH , *DIELECTRICS , *DIELECTRIC properties , *PERMITTIVITY , *ELECTRIC conductivity - Abstract
• Calcium bismuth borovanadate glasses were synthesized via melt quench technique. • Total AC conductivity exhibited a pattern consistent of almond wests power law. • Electrical conductivity increases upto x = 10 mol% and decreases for x = 15 & 20 mol%. • Dielectric studies reflect non-Debye type behaviour. This study explores various glass compositions within calcium bismuth borovanadate glass system, produced through melt quenching. The investigation focuses on AC conductivity, electric modulus formulation, and dielectric properties (ε ′ and ε ″). The AC conductivity and dielectric constants exhibit an increasing trend with rising CaO content until 10 mol%, followed by a decline for x = 15 and x = 20 mol%. Temperature and frequency-dependent conductivity reveal a dual plateau between 423 K and 523 K. The Almond west model is applied to fit AC conductivity data, extracting parameters such as direct current conductivity, crossover frequency, and frequency exponent. The glass samples demonstrate diverse conduction mechanisms, including small polaron quantum mechanical tunnelling and CBH conduction. The activation energy values for direct current conduction (E dc) ranging from 0.539 to 0.716 eV (at lower freq.) and electric modulus (E R) (0.531 to 0.707 eV) is nearly identical. Non-Debye type behaviour is reflected by dielectric studies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
196. Accelerated versus Slow In Vitro Aging Methods and Their Impact on Universal Chromatic, Urethane-Based Composites
- Author
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Nicoleta Ilie
- Subjects
aging ,resin-based composites ,dynamic-mechanical analysis ,hardness ,modulus ,universal chromatic ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Structural coloring of dental resin-based composites (RBC) is used to create universal chromatic materials designed to meet any aesthetic need, replacing the mixing and matching of multiple shades. The microstructural adjustments to create this desideratum involve nanoscale organic–inorganic core–shell structures with a particular arrangement. The generally higher polymer content associated with these structures compared to universal chromatic RBCs colored by pigments, which in their microstructure come close to regularly shaded RBCs, can influence the way the material ages. Accelerated and slow aging up to 1.2 years of immersion in artificial saliva at 37 °C were therefore compared in relation to their effects on the materials described above and in relation to the immersion conditions prescribed by standards. Quasi-static and viscoelastic parameters were assessed to quantify these effects by a depth-sensing indentation test equipped with a DMA module. The microstructure of the materials was characterized by scanning electron microscopy. The results convincingly show a differentiated influence of the aging protocol on the measured properties, which was more sensitively reflected in the viscoelastic behavior. Accelerated aging, previously associated with the clinical behavior of RBCs, shows a 2- to 10-fold greater effect compared to slow aging in artificial saliva of up to 1.2 years, highly dependent on the microstructure of the material.
- Published
- 2023
- Full Text
- View/download PDF
197. Physical, Thermal, and Mechanical Characterization of PMMA Foils Fabricated by Solution Casting
- Author
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Sneha Samal, Barbora Svomova, Monika Spasovová, Ondřej Tyc, David Vokoun, and Ivo Stachiv
- Subjects
PMMA ,toluene ,glass transition ,modulus ,as-cast ,glass substrate ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The physical, thermal, structural, and mechanical properties of poly(methyl methacrylate) PMMA foils cast from solutions of toluene were investigated by differential scanning calorimetry, optical microscope, Fourier infrared spectroscopy, and dynamical mechanical analysis. The PMMA foils were prepared from a different ratio of PMMA powder with toluene solvent by the solution cast method. The surface features, glass transition temperature, and C-H bonds of foils were investigated and compared with commercial PMMA foil. The mechanical characterization of foils was examined by using static and dynamic loads in axial and transverse modes. The tensile behaviors of the commercial and as-prepared foils were investigated by using a strain rate of 0.01/s. The dynamical behavior of the foils was tested in tensile mode using 0.1 N of stress with a frequency of 1 Hz for the determination of storage, loss modulus, and damping values of the tan delta. A significant shape memory was observed in all of the prepared PMMA foils. The solution cast method allows for tuning the glass transition temperature of polymer foil that could easily integrate with the NiTi alloy phase transition temperature to fabricate a suitable composite structure. Integrating both structures will open the flexibility in bistable actuators in composite structures as a function of thermal cycles.
- Published
- 2023
- Full Text
- View/download PDF
198. Number-Theoretical Methods of Factoring Composite Numbers and Calculating the Discrete Logarithm.
- Author
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Semotiuk, M. V.
- Subjects
- *
COMPOSITE numbers , *LOGARITHMS , *EXPONENTIAL functions , *ARITHMETIC , *NUMBER systems , *FACTORIZATION - Abstract
The article is devoted to the new application of number-theoretic transforms. Representing number systems by these transforms allows us to create fundamentally new and efficient algorithms for factoring numbers and to calculate period of the exponential function and of the discrete logarithm. The factorization algorithm allows us to decompose any finite product into factors in one run, it is an exact test of number simplicity. This algorithm is based on representing number systems by a number-theoretic transforms and has no analogs in the world since it uses only simple arithmetic operations. Properties of number simplicity or other number properties are not applied. Thus, number factoring and calculations of the exponential function period and of the discrete logarithm are simple arithmetic operations that are performed in a finite time and belong to the complexity class P. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
199. The influence of pigment modulus on failure resistance of paper barrier coatings.
- Author
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Zhu, Yaping, Bousfield, Douglas, and Gramlich, William
- Subjects
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PIGMENTS , *WATER vapor , *LATEX , *RUBBER , *POLYETHYLENE terephthalate - Abstract
Pigments are often used in water borne barrier coatings but tend to make the coatings prone to failure. The pigment properties effects on this issue is lacking in literature. In this work, coatings that used pigments with different moduli but with similar size and aspect ratio were characterized in terms of water vapor resistance before and after folding. Coatings with talc had better water vapor resistance than coatings with similar sized kaolin. Talc also limited the degradation of barrier properties when folded. Coatings with metalized poly(ethylene terephthalate) (PET) flakes had better failure resistance than coatings with similarly sized rigid mica. Both results are likely caused by the ability of the low modulus pigment to deform and allow for strain to occur in the pigment as well as the latex phase. Styrene-butadiene (SB) and natural rubber (NR) latex coatings had a better failure resistance than styrene-acrylate (SA) latex, which is likely due to their low glass transition temperatures and high strain-to-failure values. However, coatings with high amounts of SB or NR latex may lead to blocking issues in production. Adding kaolin into SA and SB latex mixtures resulted in improved water vapor barrier property and failure resistance. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
200. Modulus characterization of cells with submicron colloidal probes by atomic force microscope.
- Author
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Lei, Xiaojiao, Li, Huiqin, Han, Yao, Li, Jinjin, Yu, Fan, and Liang, Qi
- Abstract
Colloidal probes have been increasingly demanded for the characterization of cellular modulus in atomic force microscope because of their well‐defined geometry and large contact area with cell. In this work, submicron colloidal probes are prepared by scanning electron microscope/focused ion beam and compared with sharp tip and micron colloidal probe, in conjunction with loading velocity and indentation depth on the apparent elastic modulus. NIM and cartilage cells are used as specimens. The results show that modulus value measured by sharp tip changes significantly with loading velocity while remains almost stable by colloidal probes. Also, submicron colloidal probe is superior in characterizing the modulus with increasing indentation depth, which could help reveal the mechanical details of cellular membrane and the modulus of the whole cell. To test the submicron colloidal probe further, the modulus distribution map of cell is scanned with submicron colloidal probe of 50 nm radius during small and large indentation depths with high spatial resolution. The outcome of this work will provide the effective submicron colloidal probe according to the effect of loading velocity and indentation depth, characterizing the mechanical properties of the cells. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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