986 research outputs found
sj-pdf-1-jcb-10.1177_0271678X231167924 - Supplemental material for Preceding transient ischemic attack was associated with functional outcome after stroke thrombectomy: A propensity score matching study
No full textSupplemental material, sj-pdf-1-jcb-10.1177_0271678X231167924 for Preceding transient ischemic attack was associated with functional outcome after stroke thrombectomy: A propensity score matching study by Jiali Xu, Wenting Guo, Jin Ma, Qingfeng Ma, Jian Chen, Haiqing Song, Changhong Ren, Sijie Li, Yuchuan Ding, Wenbo Zhao and Xunming Ji in Journal of Cerebral Blood Flow & Metabolism</p
Novel calixarene-based porous organic polymers with superfast removal rate and ultrahigh adsorption capacity for selective separation of cationic dyes
Full text linkExploring novel porous adsorbents for efficient water purification is a significant and urgent task. Two novel calixarene-based porous organic polymers (POPs) namely POP-8F and POP-10F were synthesized via a simple and mild reaction using octafluoronaphthalene and decafluorobiphenyl as the crosslinker. The Fourier transform infrared spectrometer, solid-state 13C NMR spectra prove the successful construction of the POPs, and thermal gravimetric analyzer curves demonstrate the good thermal stabilities. Combining the advantages of porous structures, abundant adsorption sites and electronegative natures, both POP-8F and POP-10F exhibit extraordinary adsorption capacities and rates towards cationic dyes including Rhodamine B (RhB), methylene blue (MB) and crystal violet (CV). Especially for RhB, the removal efficiency can reach nearly 99 % within 4 min and the pseudo-second-order rate constant of POP-8F is 0.04386 g mg−1 min−1. Notably, the maximum adsorption capacity of POP-8F towards RhB is 2433 mg g−1, surpassing all the previously reported porous adsorbents including covalent organic frameworks, metal organic frameworks, POPs, biomass adsorbents, activated carbons, etc. In addition, both POP-8F and POP-10F can selectively adsorb cationic dyes among the mixtures of cationic dyes and anionic dyes. More importantly, the calixarene-based POPs can efficiently remove cationic dyes through a simple column filtration and exhibit excellent reusability properties. All the above characteristics make POP-8F and POP-10F excellent porous adsorbents for water pollutant treatment and purificatio
TUe-excellent-buildings/journal_paper_two_scale_method_bolted_connections_elevated_temperatures: code_and_scripts
No full text<p>This repository provides all code and scripts needed to reproduce the finite element simulations presented in:</p>
<p>Xu Q; Hofmeyer H; Maljaars J: A two-scale method to include essential behaviour of bolted connections in structures including elevated temperatures, Theoretical and Applied Mechanics Letters.</p>
<p>The code and scripts have been provided by Qingfeng Xu, fall under his responsibility, and have not been checked on the code level by coauthors and/or supervisors.</p>
Does Health Insurance Coverage Lead to Better Health and Educational Outcomes? Evidence from Rural China
Full text linkUsing 2006 China Agricultural Census (CAC), we examine whether the introduction of the New Cooperative Medical System (NCMS) has affected child mortality, maternal mortality, and school enrollment of the 6-16 years olds. Our data cover 5.9 million people living in eight low-income rural counties, of which four adopted the NCMS by 2006 and four did not adopt it until 2007. Raw data suggest that enrolling in NCMS is associated with better school enrollment and lower mortality of young children and pregnant women. However, using a difference-in-difference propensity score method, we find most of these differences are driven by the endogenous introduction and take-up of NCMS, and out method overcomes classical propensity score matching's failure to address the selection bias. While the NCMS does not affect child mortality and maternal mortality, it does help improve the school enrollment of six-year-olds.
TAVR for Severe Aortic Valve Stenosis with LVOT Stenosis: A Case Report
Full text linkQing Zhang, Yao Xu, Hao Wang, Xuelian Pang, Qingfeng Meng Department of Cardiology, Qilu Hospital of Shandong University, Qingdao, People’s Republic of ChinaCorrespondence: Xuelian Pang; Qingfeng Meng, Email [email protected]; [email protected]: Transcatheter aortic valve replacement (TAVR) has been recently indicated for the treatment of patients with severe aortic stenosis in all risk profiles. At present, TAVR has become mature at home and abroad, but the relevant experience is deficient in the treatment of aortic valve stenosis with outflow tract stenosis. One case of a high-risk surgical patient was included in this paper who suffered from severe aortic valve stenosis with left ventricular outflow tract (LVOT) stenosis. In this case, TAVR was performed with deep implantation of a new valve and both aortic valve stenosis and LVOT stenosis were treated through a single TAVR procedure. This case highlights the vital role of such treatment in dealing with both aortic valve stenosis and LVOT stenosis through a single TAVR procedure, thus providing valuable information for similar cases.Keywords: severe aortic valve stenosis, left ventricular outflow tract, LVOT, stenosis, transcatheter aortic valve replacement, TAV
Multiferroic CoFe2O4-BiFeO3 core-shell nanofibers and their nanoscale magnetoelectric coupling
No full textMultiferroic CoFe2O4-BiFeO3 (CFO-BFO) core-shell nanofibers were synthesized by coaxial electrospinning. The spinel structure of CFO and perovskite structure of BFO were confirmed by x-ray diffraction and high-resolution transmission electron microscopy. The core-shell configuration of nanofibers was verified by scanning electron microscopy and transmission electron microscopy images. The macroscopic ferromagnetic property of core-shell nanofibers was demonstrated by magnetic hysteresis loop. The local magnetoelectric (ME) coupling was confirmed by using dual frequency piezoresponse force microscopy (PFM) under an external magnetic field, showing magnetically induced evolution of piezoresponse and domain structure. The ferroelectric characteristics are demonstrated by the switching spectroscopy PFM. From PFM hysteresis and butterfly loops, it is observed that the piezoresponse amplitude is reduced while coercive voltage increased under external in-plane magnetic field, induced through the mechanical interactions between magnetostrictive CFO and piezoelectric BFO, from which the lateral ME coupling can be estimated quantitatively. The nanofibers thus can find a variety of applications as a one-dimensional multiferroic material
Shape-stabilized phase change composites enabled by lightweight and bio-inspired interconnecting carbon aerogels for efficient energy storage and photo-thermal conversion
No full textCarbon aerogels have been widely studied due to their high specific surface areas, strong adsorption capabilities and good thermal properties, which can be used to develop shape-stabilized phase change materials (PCMs). The porous framework of carbon aerogels plays a crucial role in enhancing the performance of composite PCMs. Here we report a lightweight and high strength three-dimensional (3D) carbon aerogel by using inexpensive biomass xanthan gum (XG) to eliminate the structural collapse and shrinkage observed in traditional polyimide (PI) carbon aerogels. The high stability of XG allows uniform dispersion of TiO2 nanoparticles in the framework, endowing the carbon aerogel with high light–thermal transfer performance. PEG 6000 was encapsulated using the high strength PI/XG/TiO2 carbon aerogel via vacuum impregnation, creating multi-functional carbon aerogel-based form-stable PCMs (CA-FSPCMs) with excellent thermal performance. The CA-FSPCMs demonstrated latent heat values up to 160.38 J g−1, with excellent thermal reliability even after 100 thermal cycles. Furthermore, their light–thermal conversion and storage efficiency exceeded 94.23%, and their thermal conductivity improved up to 0.82 W m−1 K−1 thanks to the PI/XG/TiO2 carbon aerogel. We also evaluated the morphology, anti-leakage performance, mechanical properties and thermal response properties of the CA-FSPCMs. The heat energy storage and release capabilities of the fabricated CA-FSPCMs are very promising for applications in temperature regulation
Enhanced stress-invariance of magnetization direction in magnetic thin films
No full textSpin valve devices, consisting of a free magnetic layer, a spacer layer, and a pinned magnetic layer, are widely used in magnetic sensors and nonvolatile magnetic memories. However, even a slight bending deformation can affect the magnetization direction of the free magnetic layer, which will change the magnetoresistance signal of the devices. Therefore, it is a challenge to develop a flexible spin valve device with controllable performance. Here, an enhanced stress-invariance of the magnetization direction in amorphous CoFeB magnetic films on flexible polyimide substrates is achieved. The uniaxial anisotropy is induced by growing on the bent substrate under a magnetic field, which aligns more magnetic domains with easy axes along the direction perpendicular to the subsequently applied stress. Theoretical calculations indicate that pre-induced anisotropy with an easy axis perpendicular to the applied stress effectively resists the change in the magnetization direction during bending. These results are of importance for realizing better performance of flexible spin valve devices and the development of flexible spintronics. Published by AIP Publishing
Covalency competition induced active octahedral sites in spinel cobaltites for enhanced pseudocapacitive charge storage
No full textSpinel cobaltites are widely presented as promising pseudocapacitive materials, however, a fundamental understanding of their structure-property relationship at an atomic level remains vague. Herein, their geometrical-site-dependent charge storage capability is investigated by substituting Co with inactive Zn and redox-active Mn. Experimental and theoretical analyses reveal that redox-active cations in octahedral sites contribute to enhanced capacitance, intrinsically determined by the covalency competition between tetrahedral and octahedral sites. The Zn2+ incorporation leads to increased occupancy of Co in octahedral sites and 2.9x increased capacitance at 1 A g(-1) current density, whereas the substituted Mn cations mainly sit in octahedral sites which can react with OH- upon cycling and separate on the spinel surface to reconstruct into delta-MnO2 nanosheets, leading to 4x increased capacitance at 1 A g(-1) current density with a detected K+ ion intercalation. Thus, the exposure of redox-active cations in octahedral sites and their intrinsic properties are influential in determining spinel oxides' pseudocapacitive properties. This work provides a general principle to optimize the pseudocapacitive properties of spinel cobaltites by deliberately selecting cations for substitution and controlling their distribution in octahedral/tetrahedral sites. It also offers a fundamental understanding of geometrical-site-dependent activity, and can effectively guide the development of spinel oxides for enhanced pseudocapacitance
Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films
No full textFlexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nano-crystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfOx/ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended
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