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81.
82.
设计了一种紧凑型P波段相对论返波振荡器,其电动力学结构是由同轴慢波结构和同轴引出结构组成的。同轴慢波结构缩小了器件的径向尺寸;同轴引出结构缩短了器件的轴向长度,且提高了束波作用效率。通过粒子模拟研究了器件内束波作用的物理过程,模拟结果表明:器件具有结构紧凑、束波作用效率高的特点。在二极管电压700 kV,电流7 kA,导引磁场1.5 T时,器件在频率833 MHz处获得较高的微波输出,饱和后输出微波的平均功率达1.58 GW,效率约为32%,器件电磁结构尺寸仅为108 mm×856 mm。 相似文献
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SnO2-ZnO hollow nanofibers were fabricated through a facile single capillary electrospinning technology. The structure and toluene sensing properties of the hollow fibers were investigated. The results indicated that the fibers possess a hollow structure, a rough porous surface after being annealed at 600 °C and the diameters are in the range of 80-160 nm. A sensor fabricated from these fibers exhibits considerable sensitivity and good stability against toluene at 190 °C, which can be attributed to the special 1D hollow structure and the promoting effect of the SnO2/ZnO heterojunction. The formation mechanism and toluene sensing mechanism of SnO2-ZnO hollow nanofibers were also discussed. 相似文献
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Kai Zhang Xuefen Wang Yin Yang Lili Wang Meifang Zhu Benjamin S. Hsiao Benjamin Chu 《Journal of Polymer Science.Polymer Physics》2010,48(10):1118-1125
In this work, aligned and molecularly oriented bone‐like PLLA semihollow fiber yarns were manufactured continuously from an optimized homogeneous polymer‐solvent‐nonsolvent system [PLLA, CH2Cl2, and dimethyl formamide (DMF)] by a single capillary electrospinning via self‐bundling technique. Here, it should be emphasized that the self‐bundling electrospinning technique, a very facile electrospinning technique with a grounded needle (which is to induce the self‐bundling of polymer nanofibers at the beginning of electrospinning process), is used for the alignment and molecular orientation of the polymer fiber, and the take‐up speed of the rotating drum for the electrospun fiber yarn collection is very low (0.5 m/s). PLLA can be dissolved in DMF and CH2Cl2 mixed solvent with different ratios. By varying the ratios of mixed solvent system, PLLA electrospun semihollow fiber with the porous inner structure and compact shell wall could be formed, the thickness of the shell and the size of inner pores could be adjusted. The results of polarized FTIR and wide angle X‐ray diffraction investigations verified that as‐prepared PLLA semihollow fiber yarns were well‐aligned and molecularly oriented. Both the formation mechanism of semihollow fibers with core‐shell structure and the orientation mechanism of polymer chains within the polymer fibers were all discussed. The as‐prepared self‐bundling electrospun PLLA fiber yarns possessed enhanced mechanical performance compared with the corresponding conventional electrospun PLLA fibrous nonwoven membranes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1118–1125, 2010 相似文献
88.
Ultra‐fine poly(vinyl alcohol) (PVA) electrospun fiber mats containing carbendazim were successfully fabricated by electrospinning from the neat PVA solution containing carbendazim in various amounts based on the weight of PVA. The morphological appearance of both the neat and the carbendazim‐loaded electrospun PVA fibers were smooth and the incorporation of carbendazim in the neat PVA solution did not affect the morphology of the resulting fibers. The average diameters of the neat and the carbendazim‐loaded electrospun PVA fibers ranged between 155 and 160 nm. The chemical integrity of the as‐loaded carbendazim in the carbendazim‐loaded electrospun PVA fiber mats was intact as verified by the 1H‐nuclear magnetic resonance spectroscopy. Thermal properties of the carbendazim‐loaded electrospun PVA fiber mats were analyzed by differential scanning calorimetry and thermogravimetric analysis. The release characteristics of the carbendazim‐loaded electrospun PVA mats were investigated by the total immersion method in distilled water at 30°C. The carbendazim‐loaded electrospun PVA mats exhibited greater amount of carbendazim released than the carbendazim‐loaded as‐cast films. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
89.
Electrospun composite nanofibers for functional applications 总被引:1,自引:0,他引:1
In this article an outline of studies conducted to date utilizing the process of electrospinning is presented. This overview for the first time focuses on research of composite nanofiber synthesis and their applications. The phenomenon of bringing materials to the nanometer scale not only improves their properties, but also creates entirely new ones. The electrospinning technique is a simple and versatile method that offers a time and cost effective production of strategic combinations of polymer and composites nanofibers useful for numerous applications highlighted in this review. The future prospects of the field are also examined. 相似文献
90.
Bin Ding Hak‐Yong Kim Se‐Chul Lee Chang‐Lu Shao Douk‐Rae Lee Soo‐Jin Park Gyu‐Beom Kwag Kyung‐Ju Choi 《Journal of Polymer Science.Polymer Physics》2002,40(13):1261-1268
Nanoscale poly(vinyl alcohol) (PVA) fiber (100–500 nm) aggregates were prepared with an electrospinning technique. Additionally, a chemical crosslinking method was used to crosslink the nanoscale PVA fiber aggregates. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and scanning electron microscopy techniques were employed to characterize the PVA fiber aggregates. The different crosslinking densities of the PVA fiber aggregates were obtained through the control of the weight percentage of glyoxal to PVA. The crosslinking densities due to heat treatment and chemical crosslinking were studied. The influence of heat treatment could be neglected in contrast to chemical crosslinking when the curing temperature was 120 °C. The primary factor that affected the crosslinking density was the volume of the chemical crosslinking agent. The results showed that the properly crosslinked PVA fiber aggregates had better antiwater solubility and mechanical properties than the noncrosslinked PVA fiber aggregates. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1261–1268, 2002 相似文献