Many polymer and organic small-molecule thin films crystallize with microstructures that twist or curve in a regular manner as crystal growth proceeds. Here we present a phase-field model that energetically favors twi...
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Many polymer and organic small-molecule thin films crystallize with microstructures that twist or curve in a regular manner as crystal growth proceeds. Here we present a phase-field model that energetically favors twisting of the three-dimensional crystalline orientation about and along particular axes, allowing morphologies such as banded spherulites, curved dendrites, and “s”- or “c”-shaped needle crystals to be simulated. When twisting about the fast-growing crystalline axis is energetically favored and spherulitic growth conditions are imposed, crystallization occurs in the form of banded spherulites composed of radially oriented twisted crystalline fibers. Due to the lack of symmetry, twisting along the normal growth direction leads to heterochiral banded spherulites with opposite twist handedness in each half of the spherulite. When twisting is instead favored about the axis perpendicular to the plane of the substrate and along the normal growth direction under diffusion-limited single-crystalline growth conditions, crystallization occurs in the form of curved dendrites with uniformly rotating branches. We show that the rate at which the branches curve affects not only the morphology but also the overall kinetics of crystallization, as the total crystallized area at a given time is maximized for a finite turning rate.
The epoxy composites with high thermal conductivity for metal-core printed circuit board(MCPCB) can be prepared by varnish coating and a hot press method. Alumina filler of plate-like shape was used as primary micro-f...
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The epoxy composites with high thermal conductivity for metal-core printed circuit board(MCPCB) can be prepared by varnish coating and a hot press method. Alumina filler of plate-like shape was used as primary micro-filler, while plate-like alumina filler, h-BN, a-BN and s-BN filler were used for blending into the plate-like alumina filler as the secondary filler. Results showed that the secondary fillers a-BN and s-BN loaded epoxy composites have higher thermal conductivity than alumina filler single-loaded composites. Also, BN filler has high thermal conductivity, but h-BN filled epoxy composite has lower thermal conductivity than alumina filled epoxy composite. The decrease of voids in epoxy composite are very important, and the filler shape and surface modification is also necessary to achieve high thermal conductivity in epoxy composite for MCPCB
The delayed neutron nuclear data are limited by its short lifetime, limited yield fraction, difficulty to obtain a well-defined sample, an inefficient (uncharacterized) experimental system, and numerical instabilities...
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Kevlar fiber are artifical fibers that have been globally commonly used due to their attributes of a high modulus, a low elongation, an impact resistance, a chemical resistance, and thermostability. Therefore, this st...
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Kevlar fiber are artifical fibers that have been globally commonly used due to their attributes of a high modulus, a low elongation, an impact resistance, a chemical resistance, and thermostability. Therefore, this study proposes nonwoven geotextiles by corporating with recycled Kevlar unidirectoinal selvage with a low production cost, crimped polyester(PET) fibers, and low-melting-point PET(LPET) fibers. The content of LPET fiber is specified as 20 wt%, while the content of Kevlar fiber varies as 0 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%. The optimal tear strength of 195 N occurs with a content of Kevlar fiber being 20 wt%.
Magnetic liquid marbles have recently attracted extensive attention for various potential applications. However, conventional liquid marbles based on iron oxide nanoparticles are opaque and inadequate for photo‐relat...
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Magnetic liquid marbles have recently attracted extensive attention for various potential applications. However, conventional liquid marbles based on iron oxide nanoparticles are opaque and inadequate for photo‐related applications. Herein, we report the first development of liquid marbles coated with magnetic lanthanide‐doped upconversion nanoparticles (UCNPs) that can convert near‐infrared light into visible light. Apart from their excellent magnetic and mechanical properties, which are attractive for repeatable tip opening and magnetically directed movements, the resultant UCNP‐based liquid marbles can act as ideal miniature reactors for photodynamic therapy of cancer cells. This work opens new ways for the development of liquid marbles, and shows great promise for liquid marbles based on UCNPs to be used in a large variety of potential applications, such as photodynamic therapy for accelerated drug screening, magnetically guided controlled drug delivery and release, and multifunctional actuation.
Commercially pure nickel (Ni) was thermomechanically processed to promote an increase in Σ3 special grain boundaries. engineering the character and chemistry of Σ3 grain boundaries in polycrystalline materials can h...
Commercially pure nickel (Ni) was thermomechanically processed to promote an increase in Σ3 special grain boundaries. engineering the character and chemistry of Σ3 grain boundaries in polycrystalline materials can help in improving physical, chemical, and mechanical properties leading to improved performance. Type-specific grain boundaries (special and random) were characterized using electron backscatter diffraction and the segregation behavior of elements such as Si, Al, C, O, P, Cr, Mg, Mn, B, and Fe, at the atomic level, was studied as a function of grain boundary character using atom probe tomography. These results showed that the random grain boundaries were enriched with impurities to include metal oxides, while Σ3 special grain boundaries showed little to no impurities at the grain boundaries. In addition, the influence of annealing time on the concentration of segregants on random grain boundaries was analyzed and showed clear evidence of increased concentration of segregants as annealing time was increased.
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