针对现有分级多PAN太赫兹无线网络MAC(Medium Access Control)协议中存在的子网形成方案不合理以及私有CTA(Channel Time Allocation)与子网内实际负载不匹配等问题,提出了一种高效低时延的MAC层优化协议.该协议采用基于泛听的按需形成...针对现有分级多PAN太赫兹无线网络MAC(Medium Access Control)协议中存在的子网形成方案不合理以及私有CTA(Channel Time Allocation)与子网内实际负载不匹配等问题,提出了一种高效低时延的MAC层优化协议.该协议采用基于泛听的按需形成子网机制避免了子网分布不均匀以及因子网形成后没有节点加入而造成的私有CTA资源浪费的问题.在子网形成后,子微微网协调器(Piconet Coordinator,PNC)根据子网内实际负载情况自适应选择私有CTA时隙资源优化机制,让有数据传输需求的节点及时将数据发出.仿真结果表明,所提出的方案能有效地降低数据帧平均接入时延,提高吞吐量以及数据帧的传输成功率.展开更多
As one of the most stable metal-organtic framework(MOF),zeolitic imidazolate framework-8(ZIF-8)has been widely studied for applications in the field of energy storage,catalysis,and environment protection.In this paper...As one of the most stable metal-organtic framework(MOF),zeolitic imidazolate framework-8(ZIF-8)has been widely studied for applications in the field of energy storage,catalysis,and environment protection.In this paper,ZIF-8 was employed to enhance the electrochemical properties and thermal stability of the electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/polyacrylonitrile(PVDF-HFP/PAN)composite separator.The results indicate that the test cells assembled with the composite separators show improved rate capability,high discharge capacity,and stable cycling performances.The addition of ZIF-8 can improve the affinity of PVDF-HFP/PAN toward liquid electrolytes,and further enhance the ionic conductivity of the composite separators.In addition,the thermal stability of the PVDF-HFP/PAN separator has been improved by ZIF-8 nanoparticles.This work can provide insight into the application of MOF materials in Li-ion batteries.展开更多
The efficient adsorption of radioactive iodine(^(129)I and^(131)I)as nuclear waste is of great importance.Polymer nanocomposites consist of metal-organic frameworks(MOFs)developing for various pollutions sorption and ...The efficient adsorption of radioactive iodine(^(129)I and^(131)I)as nuclear waste is of great importance.Polymer nanocomposites consist of metal-organic frameworks(MOFs)developing for various pollutions sorption and separation have attracted much attention.This study reports the fabrication of magnetic polyacrylonitrile(PAN)/zeolitic imidazolate frameworks(ZIF-8)nanocomposites,PAN/ZIF-8(x%)/Fe_(3)O_(4),x=30 and 50,as iodine capture adsorbents.The PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposite beads were fabricated via the phase inversion method,and their potential for iodine capture and separation in solution and vapor was investigated through UV-vis and weighing methods,respectively.Also,antibacterial activity of the as-prepared beads was assessed against E.coil and S.aureus.The as-fabricated compounds were studied by various techniques such as Fourier-transform infrared,X-ray diffraction,scanning electron microscope,energy-dispersive X-ray spectroscopy mapping,transmission electron microscope,N_(2)adsorption isotherm,and vibrating sample magnetometer.The iodine capture results showed that the efficiency of nanocomposites is remarkably higher than the pure PAN beads.Additionally,the asprepared nanocomposite adsorbents displayed higher capture capacities for iodine vapor(1524-4345mg·g^(-1))than iodine solution(187-295 mg·g^(-1)).The as-obtained magnetic nanocomposites can be successfully separated from polluted media by simple filtration or an external magnet,regenerated through washing with ethanol,and reused.Fast capturing,high sorption capacity,rapid separation,and good reusability make the PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposites highly effective adsorbents for the separation of iodine from wastewater.Additionally,PAN/ZIF-8(50%)/Fe_(3)O_(4)bead can be considered as a potential new antibacterial agent for water and wastewater treatment.展开更多
A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbo...A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.展开更多
In this study, the effect of combining different molecular domains on single platform has been reported that revealed a proper packing and interpenetration of fullerene spheres with the monomeric species. The fabricat...In this study, the effect of combining different molecular domains on single platform has been reported that revealed a proper packing and interpenetration of fullerene spheres with the monomeric species. The fabricated IPN system exhibits hydrophobic behavior in nature. An interpenetrating polymer network (IPN) of fullerene-based poly (methyl hydro siloxane) (PMHS) and polyacrylonitrile (PAN) was prepared. The synthesized polymer network was characterized using infrared (IR) spectroscopy, differential scanning calorimetric analysis (DSC), and scanning electron microscopic (SEM) technique. The IPN was analyzed by IR spectroscopy, which depicts presence of fullerene at 500 cm<sup>−1</sup> and 1632 cm<sup>−1</sup>, presence of PHMS at 1050 cm<sup>−1</sup>, 1250 cm<sup>−1</sup>, 2225 cm<sup>−1</sup>, and 3000 cm<sup>−1</sup> and presence of PAN at 3077 cm<sup>−1</sup>, 1299 cm<sup>−1</sup>, 1408 cm<sup>−1</sup> and 2083 cm<sup>−1</sup>. Shifting in band positions indicated the interpenetration of the reacting species. DSC endotherm showed crystalline peak (T<sub>c</sub>) at 117˚C, which indicated the crystalline nature of the synthesized IPN. The absence of T<sub>g</sub> peak and clear observable T<sub>c</sub> peak revealed crystalline behavior of polymeric network. The microstructure of the polymer network was observed by SEM technique, which revealed transparent and dual-phase morphology of the IPN surface. The fluorescent emission spectra of polymeric network were recorded on a spectrofluorometer which revealed fluorescent excitation and emission spectra of the IPN. The Emission spectra generated by radiative decay of excitations exhibit a maximal peak at 450 nm, suggesting that the synthesized IPN nanosheets were typically high-intensity blue light emitting materials. The FTIR investigations revealed multiple non-covalent interactions achieved by polymerization with physical anchoring on the polymeric network surfaces. Such interactions can be recognized as the driving force for the fabrication of hydrophobic flexible silicon-based materials with a self-cleansing action.展开更多
以SBA-15为硬模板剂,采用溶剂挥发诱导煤基沥青烯与聚丙烯腈(PAN)自组装,制备了氮掺杂有序介孔炭(NOMC)。通过CO_(2)活化,进一步提升NOMC的比表面积及电容性能。结果表明,SBA-15、沥青烯、PAN的比例为1∶1.2∶4.8时,800℃炭化所得炭材...以SBA-15为硬模板剂,采用溶剂挥发诱导煤基沥青烯与聚丙烯腈(PAN)自组装,制备了氮掺杂有序介孔炭(NOMC)。通过CO_(2)活化,进一步提升NOMC的比表面积及电容性能。结果表明,SBA-15、沥青烯、PAN的比例为1∶1.2∶4.8时,800℃炭化所得炭材料成炭率与有序性均较高。900℃活化后其比表面积、孔容及孔径依次为602.1 m 2/g,0.426 cm 3/g,3.808 nm,且比电容达到127.2 F/g,相比未活化,提升了41.8%。展开更多
基金supported by National Natural Science Foundation of China(12002295)Key Scientific Research Project of Education Department of Hunan Province,Xiangtan City,China(22A0113)Major Science and Technology Projects of Xiangtan Science and Technology Bureau(GX-ZD202210011).
文摘As one of the most stable metal-organtic framework(MOF),zeolitic imidazolate framework-8(ZIF-8)has been widely studied for applications in the field of energy storage,catalysis,and environment protection.In this paper,ZIF-8 was employed to enhance the electrochemical properties and thermal stability of the electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/polyacrylonitrile(PVDF-HFP/PAN)composite separator.The results indicate that the test cells assembled with the composite separators show improved rate capability,high discharge capacity,and stable cycling performances.The addition of ZIF-8 can improve the affinity of PVDF-HFP/PAN toward liquid electrolytes,and further enhance the ionic conductivity of the composite separators.In addition,the thermal stability of the PVDF-HFP/PAN separator has been improved by ZIF-8 nanoparticles.This work can provide insight into the application of MOF materials in Li-ion batteries.
基金financial support(SCU.SC1400.29011)from the Shahid Chamran University of Ahvaz。
文摘The efficient adsorption of radioactive iodine(^(129)I and^(131)I)as nuclear waste is of great importance.Polymer nanocomposites consist of metal-organic frameworks(MOFs)developing for various pollutions sorption and separation have attracted much attention.This study reports the fabrication of magnetic polyacrylonitrile(PAN)/zeolitic imidazolate frameworks(ZIF-8)nanocomposites,PAN/ZIF-8(x%)/Fe_(3)O_(4),x=30 and 50,as iodine capture adsorbents.The PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposite beads were fabricated via the phase inversion method,and their potential for iodine capture and separation in solution and vapor was investigated through UV-vis and weighing methods,respectively.Also,antibacterial activity of the as-prepared beads was assessed against E.coil and S.aureus.The as-fabricated compounds were studied by various techniques such as Fourier-transform infrared,X-ray diffraction,scanning electron microscope,energy-dispersive X-ray spectroscopy mapping,transmission electron microscope,N_(2)adsorption isotherm,and vibrating sample magnetometer.The iodine capture results showed that the efficiency of nanocomposites is remarkably higher than the pure PAN beads.Additionally,the asprepared nanocomposite adsorbents displayed higher capture capacities for iodine vapor(1524-4345mg·g^(-1))than iodine solution(187-295 mg·g^(-1)).The as-obtained magnetic nanocomposites can be successfully separated from polluted media by simple filtration or an external magnet,regenerated through washing with ethanol,and reused.Fast capturing,high sorption capacity,rapid separation,and good reusability make the PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposites highly effective adsorbents for the separation of iodine from wastewater.Additionally,PAN/ZIF-8(50%)/Fe_(3)O_(4)bead can be considered as a potential new antibacterial agent for water and wastewater treatment.
基金Project(2006CB600903) supported by the National Basic Research Program of China
文摘A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.
文摘In this study, the effect of combining different molecular domains on single platform has been reported that revealed a proper packing and interpenetration of fullerene spheres with the monomeric species. The fabricated IPN system exhibits hydrophobic behavior in nature. An interpenetrating polymer network (IPN) of fullerene-based poly (methyl hydro siloxane) (PMHS) and polyacrylonitrile (PAN) was prepared. The synthesized polymer network was characterized using infrared (IR) spectroscopy, differential scanning calorimetric analysis (DSC), and scanning electron microscopic (SEM) technique. The IPN was analyzed by IR spectroscopy, which depicts presence of fullerene at 500 cm<sup>−1</sup> and 1632 cm<sup>−1</sup>, presence of PHMS at 1050 cm<sup>−1</sup>, 1250 cm<sup>−1</sup>, 2225 cm<sup>−1</sup>, and 3000 cm<sup>−1</sup> and presence of PAN at 3077 cm<sup>−1</sup>, 1299 cm<sup>−1</sup>, 1408 cm<sup>−1</sup> and 2083 cm<sup>−1</sup>. Shifting in band positions indicated the interpenetration of the reacting species. DSC endotherm showed crystalline peak (T<sub>c</sub>) at 117˚C, which indicated the crystalline nature of the synthesized IPN. The absence of T<sub>g</sub> peak and clear observable T<sub>c</sub> peak revealed crystalline behavior of polymeric network. The microstructure of the polymer network was observed by SEM technique, which revealed transparent and dual-phase morphology of the IPN surface. The fluorescent emission spectra of polymeric network were recorded on a spectrofluorometer which revealed fluorescent excitation and emission spectra of the IPN. The Emission spectra generated by radiative decay of excitations exhibit a maximal peak at 450 nm, suggesting that the synthesized IPN nanosheets were typically high-intensity blue light emitting materials. The FTIR investigations revealed multiple non-covalent interactions achieved by polymerization with physical anchoring on the polymeric network surfaces. Such interactions can be recognized as the driving force for the fabrication of hydrophobic flexible silicon-based materials with a self-cleansing action.
文摘以SBA-15为硬模板剂,采用溶剂挥发诱导煤基沥青烯与聚丙烯腈(PAN)自组装,制备了氮掺杂有序介孔炭(NOMC)。通过CO_(2)活化,进一步提升NOMC的比表面积及电容性能。结果表明,SBA-15、沥青烯、PAN的比例为1∶1.2∶4.8时,800℃炭化所得炭材料成炭率与有序性均较高。900℃活化后其比表面积、孔容及孔径依次为602.1 m 2/g,0.426 cm 3/g,3.808 nm,且比电容达到127.2 F/g,相比未活化,提升了41.8%。
