다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

비만아 부모의 돌봄 경험: q 방법론

A review of shape memory alloy research, applications and opportunities

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

In this paper, nanocomposites based on epoxy matrix with nano-sized multi-walled carbon nanotubes (MWCNTs), Fe3O4 and Fe fillers have been developed due to the application in electromagnetic interference (EMI) shielding. The nanocomposites specimens with different fillers, as well as varied filler weight fraction have been prepared. The microwave absorption of these nanocomposites specimens have been verified by vector network analyzer. Furthermore, trilayer-type laminated nanocomposites containing a matching layer with 15 wt% nano-Fe3O4, an absorbing layer with 5 wt% CNTs and a reflecting layer with 10 wt% CNTs have been designed and fabricated. Moreover, the permittivity and the permeability for each type of composites are tested as well. Experimental results show that such trilayer-type laminated nanocomposite has excellent micro-wave absorption effect in the frequency band (from 13 GHz to 40 GHz) up to 40 dB, especially in high frequency section. The achieved peak values of the fabricated laminated nanocomposites exceed 100 dB.

EMI shielding performance of nanocomposites with MWCNTs, nanosized Fe3O4 and Fe

Auxetic mechanical metamaterials, which expand transversally when axially stretched, are widely used in flexible electronics and aerospace. However, these chiral metamaterials suffer from three severe limitations as a typical auxetic metamaterials: narrow strain range, non-tunable mechanical behaviors, and fixed properties after fabrication. In this work, 4D printing chiral metamaterials with tunable, programmable, and reconfigurable properties are developed. The deformation mode transforms from bending dominated to stretching dominated under large deformation, leading to the stress–deformation (σ–λ) behavior of the auxetic metamaterials similar to those of the biomaterials (“J”shaped), such as tissues or organs. The programmability and reconfigurability of the developed chiral metamaterials allow mechanical behavior to change between different biomaterials with high precision. Furthermore, scaffolds with personalized mechanical properties as well as configurations and metamaterials-based light-emitting diode integrated devices demonstrate potential applications in tissue engineering and programmable flexible electronics.

4D Printing Auxetic Metamaterials with Tunable, Programmable, and Reconfigurable Mechanical Properties

Self-heating fiber reinforced polymer composite using meso/macropore carbon nanotube paper and its application in deicing

Personalized 4D printing of bioinspired tracheal scaffold concept based on magnetic stimulated shape memory composites

Electromechanical instability may occur in dielectric elastomer films due to the coupling between mechanical forces and electric fields. According to Zhao and Suo [Appl. Phys. Lett. 91, 061921 (2007)], free-energy in any form, which consists of elastic strain energy and electric energy, can be used to analyze the electromechanical stability of dielectric elastomer. By taking the permittivity as a variable depending on the deformation in a free energy function, a relationship is established among critical nominal electric field, critical real electric field, nominal stress, and principal stretch ratios. The accurate expressions of these parameters are presented for a special equal biaxial stretch case. All the results obtained by utilizing the single material constant neo-Hookean elastic strain energy model coincide with the conclusions by Zhao and Suo.

Yanju Liu

Papers

EMI shielding performance of nanocomposites with MWCNTs, nanosized Fe3O4 and Fe

4D Printing Auxetic Metamaterials with Tunable, Programmable, and Reconfigurable Mechanical Properties

Self-heating fiber reinforced polymer composite using meso/macropore carbon nanotube paper and its application in deicing

Personalized 4D printing of bioinspired tracheal scaffold concept based on magnetic stimulated shape memory composites

Electromechanical stability of dielectric elastomer