针对羰基铁粉吸收剂在温度较高时易被氧化的问题,采用水热法制备了氧化锌包覆羰基铁粉核壳结构复合粒子,并分别将羰基铁粉和氧化锌/羰基铁粉核壳粒子与石蜡混合,制备复合材料。结果表明,氧化锌纳米棒致密的包覆在羰基铁粉颗粒表面形成...针对羰基铁粉吸收剂在温度较高时易被氧化的问题,采用水热法制备了氧化锌包覆羰基铁粉核壳结构复合粒子,并分别将羰基铁粉和氧化锌/羰基铁粉核壳粒子与石蜡混合,制备复合材料。结果表明,氧化锌纳米棒致密的包覆在羰基铁粉颗粒表面形成海胆状核壳结构复合粒子,正是这种结构将羰基铁粉颗粒与空气隔绝,使得复合粒子的抗氧化性能得到显著改善。与羰基铁粉复合吸波材料相比,氧化锌/羰基铁粉核壳粒子的复合材料吸收峰稍向低频移动,反射损耗小于-5 d B的带宽几乎保持不变,在不改变电磁吸波性能的前提下,提高了羰基铁粉粒子的使用温度。展开更多
Zinc oxide nanoscale powder has been synthesized by a hydrothermal route using zinc sulfate and sodium hydroxide. The as-prepared powder was annealed at 600 ℃ for 2 h and then characterized by X-ray diffraction（XRD...Zinc oxide nanoscale powder has been synthesized by a hydrothermal route using zinc sulfate and sodium hydroxide. The as-prepared powder was annealed at 600 ℃ for 2 h and then characterized by X-ray diffraction（XRD）, scanning electron microscopy and infra-red Fourier transformed spectroscopy. XRD measurements have shown a Zn O hexagonal wurtzite polycrystalline structure with good crystallinity and the formation of a new sodium pyrosulfate phase in the as-prepared powder. The annealing improves the crystalline quality of the powder and transforms the sodium pyrosulfate phase to a sodium sulfate one. The thermal treatment does not affect the lattice parameters and the Zn–O bond length but improves the random orientation of the Zn O crystallites growth.Zn O crystallites have an interconnected-nano-needles morphology forming irregular shaped aggregates. The size of the crystallites is about 20 nm. EDX analysis has shown the presence of C and S in addition to Zn and O. FTIR spectra confirm the formation of Zn O and sodium sulfate. The synthesized Zn O powder has a very high crystalline quality and the used method is a very advantageous one for the fabrication of nanosized metal oxides from inorganic reactants for photo-catalysis applications.展开更多
Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many micro...Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. Zn O-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. Zn O is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered Zn O-NPs antibacterial activity including testing methods, impact of UV illumination, Zn O particle properties(size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species(ROS) including hydrogen peroxide(H2O2), OH-(hydroxyl radicals), and O2-2(peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to Zn O-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions.These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on Zn O abrasive surface texture. One functional application of the Zn O antibacterial bioactivity was discussed in food packaging industry where Zn O-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of Zn O-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.展开更多
基于微电子机械系统制造技术的MEMS压电水听器和矢量水听器具有小型化、低功耗、低成本、易成阵、无源、噪音低等优点。对基于ZnO薄膜的MEMS水听器和矢量水听器进行了研究,测试结果表明,硅微压电水听器的灵敏度为-192 d B(ref.1 V/μPa)...基于微电子机械系统制造技术的MEMS压电水听器和矢量水听器具有小型化、低功耗、低成本、易成阵、无源、噪音低等优点。对基于ZnO薄膜的MEMS水听器和矢量水听器进行了研究,测试结果表明,硅微压电水听器的灵敏度为-192 d B(ref.1 V/μPa),基本达到实用化的要求。MEMS压电矢量水听器等效声压灵敏度为-229.5 d B(ref.1 V/μPa),比同类型压阻式MEMS矢量水听器的灵敏度高17 d B,但还未达到实用化要求。为了进一步提高MEMS矢量水听器的灵敏度,设计了具有U形槽的压电复合悬臂梁结构和电极串联结构,采用具有更高压电系数的掺钒ZnO薄膜作为压电层,并对MEMS制备工艺进行了改进,有望显著提高MEMS矢量水听器的灵敏度。展开更多
随着电压等级升高,特高压直流输电工程的过电压水平也明显增大,而直流控制保护整定和避雷器参数配置又都是从各自的角度出发进行选择的,因此,十分有必要对控制保护与避雷器动作特性的配合进行研究。用于特高压直流换流站绝缘配合研究的...随着电压等级升高,特高压直流输电工程的过电压水平也明显增大,而直流控制保护整定和避雷器参数配置又都是从各自的角度出发进行选择的,因此,十分有必要对控制保护与避雷器动作特性的配合进行研究。用于特高压直流换流站绝缘配合研究的控制策略往往采用国际大电网会议(international council on large electric systems,CIGRE)推荐的简化控制策略,基于简化控制策略的保护动作时序和实际有一定差异,会对过电压和避雷器的仿真结果有较大影响。基于云广特高压直流输电工程实际控制保护策略,通过理论分析和仿真研究了交流侧相间冲击、最高YY换流变阀侧接地和金属回线开路3种典型过电压工况,对比了云广特高压工程实际控制保护不同的时延对避雷器动作特性的影响。在这3种工况下,云广特高压工程实际控制保护策略与避雷器配合满足运行要求,保护时延还有一定的可调节裕度,可供其他直流工程参考借鉴。展开更多
Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6A...Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6Al2O9 composite oxides are obtained by the calcination of ZnxAly（OH）2（CO3）z·x H2 O precursor,and the Ni/Zn O-Zn6Al2O9（6.0 wt% Ni O） adsorbents are prepared by wetness impregnation method. The phase,acid strength,acid type and quantity,morphology,and thermal properties were characterized by X-ray diffraction,temperature-programmed desorption of ammonia,pyridine-adsorbed infrared spectrum,high-resolution transmission electron microscopy,and Thermo Gravimetry-Derivative Thermo Gravimetry（TG-DTG）,respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/gcat. The kinetic studies indicated that the active energy of RADS（49.4 k J/mol） could reach nano-sized Zn O,the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high SBET. Also,there are some extents of aromatization reactions that occur,which can be contributed to the B？nsted acid rooted in Zn6Al2O9 composite oxide,and the octane number of products can be preserved well.展开更多
New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer Si O2/Zn O: Al/Ce O2-Ti O2/Si O2 films onto glass substrates at low temperature by radio freq...New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer Si O2/Zn O: Al/Ce O2-Ti O2/Si O2 films onto glass substrates at low temperature by radio frequency magnetron sputtering. Optimum thickness of Si O2, Zn O: Al(ZAO) and Ce O2-Ti O2(CTO) films were designed with the aid of thin film design software. The degree of antireflection can be controlled by adjusting the thickness and refractive index. The outer Si O2 film can diminish the interference coloring and increase the transparency; the inner Si O2 film improves the adhesion of the coating on the glass substrate and prevents Ca2+, Na+ in the glass substrate from entering the ZAO film. The average transmittance in the visible light range increases by nearly 18%-20%, as compared to double layer ZAO/CTO films. And the films display high infrared reflection rate of above 75% in the wavelength range of 10-25 μm and good UV absorption(> 98%) properties. These systems are easy to produce on a large scale at low cost and exhibit high mechanical and chemical durability. The triple functional films with high UV absorption, antireflective and high infrared reflection rate will adapt to application in flat panel display and architectural coating glass, automotive glass, with diminishing light pollution as well as decreasing eye fatigue and increasing comfort.展开更多
文摘针对羰基铁粉吸收剂在温度较高时易被氧化的问题,采用水热法制备了氧化锌包覆羰基铁粉核壳结构复合粒子,并分别将羰基铁粉和氧化锌/羰基铁粉核壳粒子与石蜡混合,制备复合材料。结果表明,氧化锌纳米棒致密的包覆在羰基铁粉颗粒表面形成海胆状核壳结构复合粒子,正是这种结构将羰基铁粉颗粒与空气隔绝,使得复合粒子的抗氧化性能得到显著改善。与羰基铁粉复合吸波材料相比,氧化锌/羰基铁粉核壳粒子的复合材料吸收峰稍向低频移动,反射损耗小于-5 d B的带宽几乎保持不变,在不改变电磁吸波性能的前提下,提高了羰基铁粉粒子的使用温度。
文摘Zinc oxide nanoscale powder has been synthesized by a hydrothermal route using zinc sulfate and sodium hydroxide. The as-prepared powder was annealed at 600 ℃ for 2 h and then characterized by X-ray diffraction（XRD）, scanning electron microscopy and infra-red Fourier transformed spectroscopy. XRD measurements have shown a Zn O hexagonal wurtzite polycrystalline structure with good crystallinity and the formation of a new sodium pyrosulfate phase in the as-prepared powder. The annealing improves the crystalline quality of the powder and transforms the sodium pyrosulfate phase to a sodium sulfate one. The thermal treatment does not affect the lattice parameters and the Zn–O bond length but improves the random orientation of the Zn O crystallites growth.Zn O crystallites have an interconnected-nano-needles morphology forming irregular shaped aggregates. The size of the crystallites is about 20 nm. EDX analysis has shown the presence of C and S in addition to Zn and O. FTIR spectra confirm the formation of Zn O and sodium sulfate. The synthesized Zn O powder has a very high crystalline quality and the used method is a very advantageous one for the fabrication of nanosized metal oxides from inorganic reactants for photo-catalysis applications.
基金support from a research university Grant number 1001/PFIZIK/814174 of Universiti Sains Malaysia(USM)
文摘Antibacterial activity of zinc oxide nanoparticles(Zn O-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. Zn O-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. Zn O is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered Zn O-NPs antibacterial activity including testing methods, impact of UV illumination, Zn O particle properties(size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species(ROS) including hydrogen peroxide(H2O2), OH-(hydroxyl radicals), and O2-2(peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to Zn O-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions.These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on Zn O abrasive surface texture. One functional application of the Zn O antibacterial bioactivity was discussed in food packaging industry where Zn O-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of Zn O-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.
文摘基于微电子机械系统制造技术的MEMS压电水听器和矢量水听器具有小型化、低功耗、低成本、易成阵、无源、噪音低等优点。对基于ZnO薄膜的MEMS水听器和矢量水听器进行了研究,测试结果表明,硅微压电水听器的灵敏度为-192 d B(ref.1 V/μPa),基本达到实用化的要求。MEMS压电矢量水听器等效声压灵敏度为-229.5 d B(ref.1 V/μPa),比同类型压阻式MEMS矢量水听器的灵敏度高17 d B,但还未达到实用化要求。为了进一步提高MEMS矢量水听器的灵敏度,设计了具有U形槽的压电复合悬臂梁结构和电极串联结构,采用具有更高压电系数的掺钒ZnO薄膜作为压电层,并对MEMS制备工艺进行了改进,有望显著提高MEMS矢量水听器的灵敏度。
文摘随着电压等级升高,特高压直流输电工程的过电压水平也明显增大,而直流控制保护整定和避雷器参数配置又都是从各自的角度出发进行选择的,因此,十分有必要对控制保护与避雷器动作特性的配合进行研究。用于特高压直流换流站绝缘配合研究的控制策略往往采用国际大电网会议(international council on large electric systems,CIGRE)推荐的简化控制策略,基于简化控制策略的保护动作时序和实际有一定差异,会对过电压和避雷器的仿真结果有较大影响。基于云广特高压直流输电工程实际控制保护策略,通过理论分析和仿真研究了交流侧相间冲击、最高YY换流变阀侧接地和金属回线开路3种典型过电压工况,对比了云广特高压工程实际控制保护不同的时延对避雷器动作特性的影响。在这3种工况下,云广特高压工程实际控制保护策略与避雷器配合满足运行要求,保护时延还有一定的可调节裕度,可供其他直流工程参考借鉴。
文摘Aiming to improve the reactive adsorption desulfurization（RADS） performances of Ni/Zn O adsorbents,ZnxAly（OH）2（CO3）z·x H2 O precursor is synthesized by coprecipitation of Zn2＋,AlO-2,and CO2-3; the Zn OZn6Al2O9 composite oxides are obtained by the calcination of ZnxAly（OH）2（CO3）z·x H2 O precursor,and the Ni/Zn O-Zn6Al2O9（6.0 wt% Ni O） adsorbents are prepared by wetness impregnation method. The phase,acid strength,acid type and quantity,morphology,and thermal properties were characterized by X-ray diffraction,temperature-programmed desorption of ammonia,pyridine-adsorbed infrared spectrum,high-resolution transmission electron microscopy,and Thermo Gravimetry-Derivative Thermo Gravimetry（TG-DTG）,respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/gcat. The kinetic studies indicated that the active energy of RADS（49.4 k J/mol） could reach nano-sized Zn O,the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high SBET. Also,there are some extents of aromatization reactions that occur,which can be contributed to the B？nsted acid rooted in Zn6Al2O9 composite oxide,and the octane number of products can be preserved well.
基金Funded by the Natural Science Foundation of Hubei Province(No.2014CFB563)the key Technology Innovation Project of Hubei Province(No.2013AAA005)China Postdoctoral Science Foundation(Nos.2013T60752 and 2012M511689)
文摘New visible transparent, UV absorption, and high infrared reflection properties have been realized by depositing multilayer Si O2/Zn O: Al/Ce O2-Ti O2/Si O2 films onto glass substrates at low temperature by radio frequency magnetron sputtering. Optimum thickness of Si O2, Zn O: Al(ZAO) and Ce O2-Ti O2(CTO) films were designed with the aid of thin film design software. The degree of antireflection can be controlled by adjusting the thickness and refractive index. The outer Si O2 film can diminish the interference coloring and increase the transparency; the inner Si O2 film improves the adhesion of the coating on the glass substrate and prevents Ca2+, Na+ in the glass substrate from entering the ZAO film. The average transmittance in the visible light range increases by nearly 18%-20%, as compared to double layer ZAO/CTO films. And the films display high infrared reflection rate of above 75% in the wavelength range of 10-25 μm and good UV absorption(> 98%) properties. These systems are easy to produce on a large scale at low cost and exhibit high mechanical and chemical durability. The triple functional films with high UV absorption, antireflective and high infrared reflection rate will adapt to application in flat panel display and architectural coating glass, automotive glass, with diminishing light pollution as well as decreasing eye fatigue and increasing comfort.
