- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Transparent Urethane Siloxane Hybrid Material for Flexible Cover Window with Ceramic-like Strength, yet Polymer-like Modulus
摘要： Any transition toward an era of flexible electronics will have to overcome mechanical limitations of materials. Specifically, the attainment of both strength and flexibility, which are generally mutually exclusive, is required including glass-like wear resistance, plastic-like compliance and a high level of strain. Here, we fabricate a urethane-methacrylate siloxane hybrid material (UMSH). It is found that the UMSH, with molecule-level hybridization of urethane linkage and methacrylate-siloxane co-networks, demonstrates ceramic-like high strength (574 MPa), yet polymer-like low modulus (8.42 GPa), and even high strain (6.3%) at fracture with excellent optical transparency. This combination of high strength, flexibility and optical transparency indicates that this is a suitable material for glass substitution and can be used as a transparent flexible cover window for foldable display.
关键词： ceramic-like strength,polymer-like modulus,Flexible cover window,molecular hybridization,urethane-methacrylate siloxane hybrid
更新于2025-09-11 14:15:04
-
The Value of Elastic Modulus Index as a Novel Surrogate Marker for Cardiovascular Risk Stratification by Dimensional Speckle-Tracking Carotid Ultrasonography
摘要： Background: Carotid intima media thickness (CIMT) and the presence of carotid plaque have been used for risk stratification of cardiovascular disease (CVD). To date, however, the association between multi-directional functional properties of carotid artery and CVD has not been fully elucidated. We sought to explore the multi-directional mechanics of the carotid artery in relation to cardiovascular risk. Methods: Four hundred one patients who underwent carotid ultrasound were enrolled between January 2010 and April 2013. A high risk of CVD was defined as more than 20% of 10-year risk based on the Framingham risk score. Using a speckle-tracking technique, the longitudinal and radial movements were analyzed in the B-mode images. Peak longitudinal and radial displacements, strain and strain rate were also measured. Beta stiffness and elastic modulus index were calculated from the radial measurements. Results: Of the overall sample, 13% (52) of patients comprised the high-risk group. In multivariate logistic regression, CIMT and elastic modulus index were independently associated with a high-risk of CVD {odds ratio (OR): 1.810 [95% confidence interval (CI) 1.249–2.622] and OR: 1.767 (95% CI: 1.177–2.652); p = 0.002, 0.006, respectively}. The combination of CIMT and elastic modulus index correlated with a high-risk of CVD more so than CIMT alone. Conclusion: The elastic modulus index of the carotid artery might serve as a novel surrogate marker of high-risk CVD. Measurement of the multi-directional mechanics of the carotid artery using the speckle tracking technique has potential for providing further information over conventional B-mode ultrasound for stratification of CVD risk.
关键词： Elastic modulus,Carotid artery,Cardiovascular disease
更新于2025-09-10 09:29:36
-
Efficient Algorithms for Synthesizing Probing Waveforms with Desired Spectral Shapes
摘要： We consider the design of constant-modulus probing waveforms to improve the spectral compatibility of radar systems with the congested radio frequency (RF) environments. We seek to synthesize radar probing waveforms with desired spectral shapes. We use a weighted least-squares (WLS) fitting approach to formulate the spectral shaping problem. We introduce two algorithms to tackle the optimization problem we encounter. Both algorithms are devised based on cyclic approaches and have guaranteed convergence of the objective values. Moreover, the proposed algorithms can be implemented via fast Fourier transforms (FFT) and hence is computationally efficient. Furthermore, we extend the proposed algorithms to deal with peak-to-average-power-ratio (PAPR) and similarity constraints, which are desirable in some radar applications. Finally, we provide several numerical examples to demonstrate the effectiveness of the proposed algorithms.
关键词： waveform design,cyclic optimization,spectral shaping,Spectrum congestion,constant-modulus,similarity constraint,peak-to-average-power-ratio (PAPR)
更新于2025-09-10 09:29:36
-
The Elastic Property of Bulk Silicon Nanomaterials through an Atomic Simulation Method
摘要： This paper reports a systematic study on the elastic property of bulk silicon nanomaterials using the atomic finite element method. The Tersoff-Brenner potential is used to describe the interaction between silicon atoms, and the atomic finite element method is constructed in a computational scheme similar to the continuum finite element method. Young’s modulus and Poisson ratio are calculated for [100], [110], and [111] silicon nanowires that are treated as three-dimensional structures. It is found that the nanowire possesses the lowest Young’s modulus along the [100] direction, while the [110] nanowire has the highest value with the same radius. The bending deformation of [100] silicon nanowire is also modeled, and the bending stiffness is calculated.
关键词： atomic finite element method,silicon nanowires,Poisson ratio,elastic property,bending stiffness,Young’s modulus
更新于2025-09-10 09:29:36
-
Study of complex impedance spectroscopic properties of La <sub/> 0.7? <i>x</i> </sub> Dy <i> <sub/>x</sub></i> Sr <sub/>0.3</sub> MnO <sub/>3</sub> perovskite oxides
摘要： The dysprosium perovskite La0.72xDyxSr0.3MnO3 [LSMO] and 0.03 [LDSMO]) compounds were prepared by the sol–gel reaction and characterized by the X-ray diffraction technique. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 311–356 K and 209–5 (cid:2) 107 Hz, respectively, by means of impedance spectroscopy. The ac and dc conductivities were studied to explore the mechanisms of conduction of LSMO and LDSMO. The insertion of a small amount of Dy3t in the La-site of LSMO perovskite oxide increases the value of the activation energy from 0.2106 to 0.5357 eV and enhances electrical resistivity values for almost two orders of magnitude.
关键词： the non-overlapping small polaron tunneling,impedance spectroscopy,correlated barrier hopping,modulus,ac conductivity
更新于2025-09-10 09:29:36
-
Properties of ta-C coatings prepared by pulsed cathodic arc source at various distances
摘要： Tetrahedral amorphous carbon (ta-C) coatings have been prepared on silicon substrates by the pulsed cathodic arc source. For the limitation of the heat flux of the carbon plasma to the sample, the diaphragm of 27 mm diameter has been used. The deposition process has been carried out at three different distances between the arc source and the substrate: 150, 215 and 265 mm. The properties of ta-C coatings have been studied by Raman spectroscopy and dynamic nanoindentation techniques. The analysis of Raman spectra parameters has revealed that the concentration of ordered aromatic rings in Csp2 cluster decreases with distance between the arc source and the substrate while the concentration of chain groups increases. Nanoindentation has shown the decrease in nanohardness and Young's modulus with the distance. Nanohardness value falls from 21 GPa to 16 GPa and Young's modulus value goes down from 197 GPa to 177 GPa. So, it’s possible to control the formation of ta-C coatings structure by changing distance between the pulsed cathodic arc source and the substrate.
关键词： ta-C coatings,nanohardness,Young's modulus,pulsed cathodic arc source,nanoindentation,Raman spectroscopy
更新于2025-09-09 09:28:46
-
[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Investigation of the Effects of High Temperature Aging on the Mechanical Behavior of Lead Free Solders
摘要： Lead free solders are renowned as interconnects in electronic packaging due to their relatively high melting point, attractive mechanical properties, thermal cycling reliability, and environment friendly chemical properties. The mechanical behavior of lead free solders is highly dependent on the operating temperature. Previous investigations on mechanical characterization of lead free solders have mainly emphasized stress-strain and creep testing at temperatures up to 125 °C. However, electronic devices, sometimes, experience harsh environment applications including well drilling, geothermal energy, automotive power electronics, and aerospace engines where solders are exposed to very high temperatures from 125-200 °C. Mechanical properties of lead free solders at elevated temperatures are limited. In this work, we have investigated the mechanical behavior SAC305 (96.5Sn-3.0Ag-0.5Cu) and SAC_Q (SAC+Bi) lead free solders at extreme high temperatures up to 200 °C. Stress-strain tests were performed on reflowed uniaxial specimens at four elevated temperatures (T = 125, 150, 175, and 200 °C). In addition, changes of the mechanical behavior of these alloys due to isothermal aging at T = 125 oC have been studied. Extreme care has been taken during specimen preparation so that the fabricated solder uniaxial test specimens accurately reflect the solder material microstructures present in actual lead free solder joints. High temperature tensile properties of the solders including initial modulus, yield stress, and ultimate tensile strength have been compared. As expected, our results show substantial degradations of the mechanical properties of lead-free solders at higher temperatures. With prior aging, these degradations become even more significant. Comparison of the results has shown that the addition of Bi to traditional SAC alloys improves their high temperature properties and significantly reduces their aging induced degradations.
关键词： Yield Stress,Ultimate Tensile Strength,Stress-Strain Curve,SAC alloy,Modulus,Lead-Free Solder,Aging
更新于2025-09-09 09:28:46
-
Young’s Modulus of Fullerene C <sub/>60</sub> –C <sub/>70</sub> Alloy Crystalline Nanowhiskers
摘要： Crystalline nanowhiskers (NWs) composed of fullerene C60 and C70 molecules, i.e., alloy NWs, were synthesized by a liquid–liquid interfacial precipitation method. The nominal composition of C70 ranged from 0 to 40 mass%. The bending tests of the alloy NWs were performed inside a high-resolution transmission electron microscope, and the deformation behavior was observed in situ. The bending force acting on the NWs were measured simultaneously by an optical deflection method, and the Young’s modulus was estimated from the resulting force–flexure curves. The average Young’s modulus was found to increase to approximately 30 GPa as the C70 composition was increased to the solubility limit. In contrast, the Young’s modulus decreased with increasing NW diameter caused by the addition of C70.
关键词： Fullerene,Bending,Young’s Modulus,Transmission Electron Microscopy,Nanowhisker
更新于2025-09-09 09:28:46
-
Quantifying the Exfoliation Ease Level of 2D Materials via Mechanical Anisotropy
摘要： The isolation of 2D materials from mother bulks into nanoscale is of vital importance for fulfilling their applications in many technological fields. Among known methods, mechanical exfoliation is one of the most widely utilized ways due to its simplicity. For a given 2D material, both its inter-layer and intra-layer bonding strengths need to be taken into accounted for understanding the exfoliation process as the former dominates the ease level for cleaving adjacent molecular layers while the later regulates the ability for resisting cracking. In this regard, strong intra-layer but weak inter-layer bonding interactions respectively lead to large and thin nanosheets, hence facile exfoliation (and vice versa). As the bonding forces can be directly reflected through elastic properties of materials, here we propose to use the ratio between the in-plane and out-of-plane elastic modulus (E) as a universal index, AIn/Out (= EIn-plane/EOut-of-plane), to quantify the ease level of a 2D material’s mechanical exfoliation. Such ratios, which can be facilely obtained from routine computational and mechanical experiments, could provide useful information for estimating suitable exfoliation methods of 2D materials.
关键词： nanosheets,elastic modulus,2D materials,mechanical exfoliation,mechanical anisotropy
更新于2025-09-09 09:28:46
-
Stress control of tensile-strained In <sub/>1?</sub><sub/><i>x</i> </sub> Ga <sub/><i>x</i> </sub> P nanomechanical string resonators
摘要： We investigate the mechanical properties of freely suspended nanostrings fabricated from tensile-stressed, crystalline In1?xGaxP. The intrinsic strain arises during epitaxial growth as a consequence of the lattice mismatch between the thin film and the substrate, and is confirmed by x-ray diffraction measurements. The flexural eigenfrequencies of the nanomechanical string resonators reveal an orientation dependent stress with a maximum value of 650 MPa. The angular dependence is explained by a combination of anisotropic Young’s modulus and a change of elastic properties caused by defects. As a function of the crystal orientation, a stress variation of up to 50% is observed. This enables fine tuning of the tensile stress for any given Ga content x, which implies interesting prospects for the study of high Q nanomechanical systems.
关键词： In1?xGaxP,tensile-strained,defects,nanomechanical string resonators,Young’s modulus,stress control
更新于2025-09-09 09:28:46