The effects of excimer light irradiation on polysilazane coatings formed on PET films with vacuum-evaporated SiO2 coatings and the effects of these coatings on gas barrier characteristics have been investigated. The t...The effects of excimer light irradiation on polysilazane coatings formed on PET films with vacuum-evaporated SiO2 coatings and the effects of these coatings on gas barrier characteristics have been investigated. The temperature during light irradiation has a large effect on the coating’s molecular structure and gas barrier characteristics. When irradiation was performed at 100℃, the polysilazane coating transformed into a silica coating, and a compact silica coating at a much lower temperature than with heat treatment alone was produced. Surface irregularities in the vapor-deposited silica coating were smoothed out by the formation of a polysilazane coating, which was transformed into a compact silica coating when irradiated with light, resulting in a significant improvement in the gas barrier characteristics. The water vapor permeability of the thin coating irradiated with excimer light at 100℃ showed only 0.04 g/m2•day (40℃, 90% RH). According to the results of investigation of temperature variation of water-vapor permeability, it is inferred that the developed film has an excellent gas barrier value, namely, 4.90 × 10–4 g/m2•day at 25℃. This gas barrier coated PET film is transparent and flexible, and can be used in the fabrication of flexible electronics. Also, the proposed fabrication method effectively provides a simple low-cost and low-temperature fabrication technique without the need for high vacuum facility.展开更多
Contemporary PET scanners for clinical use have spatial-resolution of 4 - 5 mm, caused by fundamental factors in medical imaging: detector sizes, free path of positrons, and non-colinearity uncertainty of annihilation...Contemporary PET scanners for clinical use have spatial-resolution of 4 - 5 mm, caused by fundamental factors in medical imaging: detector sizes, free path of positrons, and non-colinearity uncertainty of annihilation photon-pairs. The drawback in resolution significantly restrained the sensitivity of PET in imaging small lesions, which could be either early-stage cancers or small metastasis. In this study, the principle for a novel scanning mode to acquire high spatial-resolution images is proposed for clinical PET scanners. The concept of equivalent position was first proposed as different angular orientations of the scanner ring, at which comparable images could be achieved. Due to this concept, a typical static PET scan can be separated into m (m ≥ 2) equivalent sub-scans at different equivalent positions, when the scanner ring is systematically adjusted to m equivalent-positions of equal distance within one detector size. In this case each detector is virtually divided into m equal sub-detectors, without physical minimizing the detector size, and imaging contributions from every 1/m part of the detector can be determined by an analytically matrix, since there are m variables and m sub-scans. This novel concept is quite feasible to contemporary design because the high spatial resolution working modes (m ≥ 2) only demand the scanner to be slightly adjustable to other angular orientations. Adding high spatial resolutions modes to the scanner only has trifling influence on contrast resolutions as all imaging events at each sub-scan are independent. The time for performing a high-resolution scan could be comparable to a typical PET scan, as long as the Poisson noises are insignificant to low-uptake voxels. As a result, for a typical scanner design e.g. 80 cm in diameter with 18F as tracers, the spatial resolution of double sub-scans (m = 2) is 2.56 mm, and 2.19 mm for triple sub-scans (m = 3), which are significant improvements. The novelty of high spatial resolution design is compatible to digital PET or any other technological evolutions.展开更多
Electromagnetic interference(EMI)shielding composites with good flexibility and weatherability properties have attracted increased attention.In this study,we combined the surface modification method of sub-atmospheric...Electromagnetic interference(EMI)shielding composites with good flexibility and weatherability properties have attracted increased attention.In this study,we combined the surface modification method of sub-atmospheric pressure glow discharge plasma with in situ atmospheric pressure surface dielectric barrier discharge plasma(APSDBD)reduction to prepare polyethylene terephthalate supported silver(Ag/PET).Due to the prominent surface modification of PET film,mild plasma reduction,and effective control of the silver morphology by polyvinylpyrrolidone(PVP),a 3.32μm thick silver film with ultralow sliver loading(0.022 wt%)exhibited an EMI shielding efficiency(SE)of 39.45 d B at 0.01 GHz and 31.56 d B at 1.0 GHz(>30 d B in the range of 0.01–1.0 GHz).The SEM results and EMI shielding analysis indicated that the high performance originated from the synergistic effect of the formation of silver nanoparticles(Ag NPs)with preferentially oriented cell-like surface morphologies and layer-by-layer-like superimposed microstructures inside,which demonstrated strong microwave reflection properties.Fourier transform infrared spectrometer and x-ray diffractometer showed that the surface structures of the heat-sensitive substrate materials were not destroyed by plasma.Additionally,APSDBD technology for preparing Ag/PET had no special requirements on the thickness,dielectric constant,and conductivity of the substrate,which provides an effective strategy for manufacturing metal or alloy films on surfaces of heat-sensitive materials at a relatively low cost.展开更多
In this study, the adsorptive properties of L-menthol, moisture vapor transmission rate, and mechanical properties of poly (ethylene terephthalate) (PET), polypropylene (PP), and their blends were evaluated in contain...In this study, the adsorptive properties of L-menthol, moisture vapor transmission rate, and mechanical properties of poly (ethylene terephthalate) (PET), polypropylene (PP), and their blends were evaluated in containers fabricated by injection molding without a compatibilizing agent. These containers intended to hold pharmaceutical solutions containing lipophilic chemicals such as L-menthol. By the addition of a small amount of PP, the moisture barrier properties of PET were effectively improved, but its anti-adsorptive property was reduced. The strength of the PET/PP blends was reduced, but some PET/PP blends were still able to bear the experimental load required for application in eye-drop containers. PET/PP = 9/1 and PET/PP = 8/2 were found to be most applicable for using in the fabrication of containers for medicinal solutions.展开更多
Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The dev...Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The development of rtmning velocity, temperature, crystallinity and theological force is investigated for the take-up velocity over a range of 6 000 - 10 000 m/min. The position of necking point, temperature rise and abrupt increase of crystallinity move closer to the spinneret with the increase of take-up velocity,展开更多
文摘The effects of excimer light irradiation on polysilazane coatings formed on PET films with vacuum-evaporated SiO2 coatings and the effects of these coatings on gas barrier characteristics have been investigated. The temperature during light irradiation has a large effect on the coating’s molecular structure and gas barrier characteristics. When irradiation was performed at 100℃, the polysilazane coating transformed into a silica coating, and a compact silica coating at a much lower temperature than with heat treatment alone was produced. Surface irregularities in the vapor-deposited silica coating were smoothed out by the formation of a polysilazane coating, which was transformed into a compact silica coating when irradiated with light, resulting in a significant improvement in the gas barrier characteristics. The water vapor permeability of the thin coating irradiated with excimer light at 100℃ showed only 0.04 g/m2•day (40℃, 90% RH). According to the results of investigation of temperature variation of water-vapor permeability, it is inferred that the developed film has an excellent gas barrier value, namely, 4.90 × 10–4 g/m2•day at 25℃. This gas barrier coated PET film is transparent and flexible, and can be used in the fabrication of flexible electronics. Also, the proposed fabrication method effectively provides a simple low-cost and low-temperature fabrication technique without the need for high vacuum facility.
文摘Contemporary PET scanners for clinical use have spatial-resolution of 4 - 5 mm, caused by fundamental factors in medical imaging: detector sizes, free path of positrons, and non-colinearity uncertainty of annihilation photon-pairs. The drawback in resolution significantly restrained the sensitivity of PET in imaging small lesions, which could be either early-stage cancers or small metastasis. In this study, the principle for a novel scanning mode to acquire high spatial-resolution images is proposed for clinical PET scanners. The concept of equivalent position was first proposed as different angular orientations of the scanner ring, at which comparable images could be achieved. Due to this concept, a typical static PET scan can be separated into m (m ≥ 2) equivalent sub-scans at different equivalent positions, when the scanner ring is systematically adjusted to m equivalent-positions of equal distance within one detector size. In this case each detector is virtually divided into m equal sub-detectors, without physical minimizing the detector size, and imaging contributions from every 1/m part of the detector can be determined by an analytically matrix, since there are m variables and m sub-scans. This novel concept is quite feasible to contemporary design because the high spatial resolution working modes (m ≥ 2) only demand the scanner to be slightly adjustable to other angular orientations. Adding high spatial resolutions modes to the scanner only has trifling influence on contrast resolutions as all imaging events at each sub-scan are independent. The time for performing a high-resolution scan could be comparable to a typical PET scan, as long as the Poisson noises are insignificant to low-uptake voxels. As a result, for a typical scanner design e.g. 80 cm in diameter with 18F as tracers, the spatial resolution of double sub-scans (m = 2) is 2.56 mm, and 2.19 mm for triple sub-scans (m = 3), which are significant improvements. The novelty of high spatial resolution design is compatible to digital PET or any other technological evolutions.
基金supported by National Natural Science Foundation of China(Nos.52077024,21773020,21673026,11505019)Natural Science Foundation of Liaoning Province(No.20180550085)Zhang Xiuling Innovation Studio of Dalian City。
文摘Electromagnetic interference(EMI)shielding composites with good flexibility and weatherability properties have attracted increased attention.In this study,we combined the surface modification method of sub-atmospheric pressure glow discharge plasma with in situ atmospheric pressure surface dielectric barrier discharge plasma(APSDBD)reduction to prepare polyethylene terephthalate supported silver(Ag/PET).Due to the prominent surface modification of PET film,mild plasma reduction,and effective control of the silver morphology by polyvinylpyrrolidone(PVP),a 3.32μm thick silver film with ultralow sliver loading(0.022 wt%)exhibited an EMI shielding efficiency(SE)of 39.45 d B at 0.01 GHz and 31.56 d B at 1.0 GHz(>30 d B in the range of 0.01–1.0 GHz).The SEM results and EMI shielding analysis indicated that the high performance originated from the synergistic effect of the formation of silver nanoparticles(Ag NPs)with preferentially oriented cell-like surface morphologies and layer-by-layer-like superimposed microstructures inside,which demonstrated strong microwave reflection properties.Fourier transform infrared spectrometer and x-ray diffractometer showed that the surface structures of the heat-sensitive substrate materials were not destroyed by plasma.Additionally,APSDBD technology for preparing Ag/PET had no special requirements on the thickness,dielectric constant,and conductivity of the substrate,which provides an effective strategy for manufacturing metal or alloy films on surfaces of heat-sensitive materials at a relatively low cost.
文摘In this study, the adsorptive properties of L-menthol, moisture vapor transmission rate, and mechanical properties of poly (ethylene terephthalate) (PET), polypropylene (PP), and their blends were evaluated in containers fabricated by injection molding without a compatibilizing agent. These containers intended to hold pharmaceutical solutions containing lipophilic chemicals such as L-menthol. By the addition of a small amount of PP, the moisture barrier properties of PET were effectively improved, but its anti-adsorptive property was reduced. The strength of the PET/PP blends was reduced, but some PET/PP blends were still able to bear the experimental load required for application in eye-drop containers. PET/PP = 9/1 and PET/PP = 8/2 were found to be most applicable for using in the fabrication of containers for medicinal solutions.
文摘Cross-over method is established to predict necking point for PET high- speed fiber spinning. Even slowly crystallizing polymers such as PET can crystallize on the spinline at sufficiently high spinning speed. The development of rtmning velocity, temperature, crystallinity and theological force is investigated for the take-up velocity over a range of 6 000 - 10 000 m/min. The position of necking point, temperature rise and abrupt increase of crystallinity move closer to the spinneret with the increase of take-up velocity,
