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《Ceramics International》2019,45(11):13923-13933
In the present study, a simple UV-assisted sonication method is used for the development of bismuth sulfide (Bi2S3) nanostructures on graphene sheets. X-ray diffraction (XRD) and Raman results indicated that graphene oxide (GO) layers are reduced. Field emission scanning electron microscopy (FESEM) images also indicated that Bi2S3 particles without rGO sheets are agglomerated. In comparison, when adding these sheets, the particles are uniformly spread (decorated) and their size is reduced significantly due to the incorporation of rGO sheets. UV–Vis studies reveal that the band gap in Bi2S3/rGO nanocomposites compared with Bi2S3 has a shift toward shorter wavelengths, suggesting some changes in the electronic band structure of Bi2S3 due to the existence of rGO sheets. Photoluminescence (PL) analysis indicated emission bands in infrared and visible regions resulting from the band edge emission and crystal defects in the samples, respectively. The electrical investigations showed reduced recombination of photogenerated carriers in the nanocomposites. Moreover, the results indicated that the concentration of rGO is an important factor in determining the optoelectrical behavior of these devices.  相似文献   
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The effects of UV-assisted TiO2-photocatalytic oxidation (PCO) inactivation of pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium) in a liquid culture using different domains of UV irradiation (A, B and C) were evaluated. Structural changes in super-coiled plasmid DNA (pUC19) and genomic DNA of E. coli were observed using gel electrophoresis to demonstrate the photodynamic DNA strand breaking activity of UV-assisted TiO2-PCO. Membrane damage in bacterial cells was observed using both a scanning electron microscope (SEM) and a confocal laser scanning microscope (CLSM). Both UVC-TiO2-PCO and UVC alone resulted in an earlier bactericidal phase (initial counts of approximately 6 log CFU/mL) in 60 s and 90 s, respectively, in liquid culture. UVC-TiO2-PCO treatment for 6 min converted all plasmid DNA to the linear form; however, under UVC irradiation alone, super-coiled DNA remained. Prolonged UVC-TiO2-PCO treatment resulted in structural changes in genomic DNA from E. coli. SEM observations revealed that bacteria suffered severe visible cell damage after UVC-TiO2-PCO treatment for 30–60 min. S. typhimurium cells showed visible damage after 30 min, which was confirmed using CLSM. All treated cells were stained red using propidium iodide under a fluorescent light.  相似文献   
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目的 高效快速获得紫外光辅助作用下碳化硅(SiC)化学机械抛光(Chemical mechanical polishing, CMP)的最佳加工参数。方法 根据化学作用与机械作用相平衡时达到最佳抛光条件的理论,通过电化学测试的方法探究抛光液pH值、过氧化氢(Hydrogen peroxide, H2O2)浓度、Fe2+浓度、紫外光功率等对基体表面氧化膜形成速率(化学作用)的影响;在最大氧化膜形成速率条件下,以材料去除率(Material removal rate, MRR)和表面粗糙度(Average roughness, Ra)为指标,通过调节抛光压力、抛光盘转速、抛光液流量等工艺参数,探究工艺参数对碳化硅加工过程中氧化膜去除速率(机械作用)的作用规律,寻求机械作用与化学作用的平衡点,获取紫外光辅助作用下SiC CMP的最佳工艺参数。结果 在pH值为3、H2O2的质量分数为4%、Fe2+浓度为0.4 mmol/L、紫外光功率为32 W时,化学作用达到最大值。在最大化学作用条件下,抛光压力、抛光盘转速、抛光液流量分别为38.68 kPa、120 r/min、90 mL/min时,化学作用与机械作用最接近于平衡点,此时材料去除率为92 nm/h,表面粗糙度的最低值为0.158 nm。结论 根据研究结果,电化学测试可以作为探究晶片表面氧化速率较高时所需加工参数的有效手段,进一步调节工艺参数,使化学作用速率与机械去除速率相匹配,高效地获得了材料去除率和表面质量较高的晶片。  相似文献   
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In this study, we explored a rapid and low-cost process for patterning in a SU-8 photoresist by thermal imprinting with a non-transparent mold such as Ni mold. One of major obstacles in the process is that the extremely good formability of uncured SU-8 even near room temperature causes the collapse of imprinted patterns during and after de-molding because a sample cannot be exposed to UV light during imprinting owing to the non-transparency of a mold. To overcome this problem, un-cured SU-8 resists were pre-treated with UV light, heat, and O2 plasma for controlling their formability, and applied to thermal imprint tests to be compared each other in terms of the replication fidelity. As a result, a SU-8 sample pre-treated with UV light for 8 s resulted in the best replication quality for given imprint conditions and mold dimensions, and we could successfully replicate micro patterns in SU-8 resist without a quartz mold. As compared with conventional UV-imprint processes, this process has potential merits such as a lower mold cost, an easier mold release and a less air-entrapment.  相似文献   
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We report on the preparation of nanocomposites consisting of biofunctionalized single-walled carbon nanotubes (BF-SWCNTs) reinforcing an ultraviolet curable epoxy polymer by means of biotin–streptavidin interactions. The as-produced laser ablation SWCNTs are biofunctionalized via acid oxidization based purification process and non-covalent functionalization using surfactant, followed by grafting the resulting nanotubes with biomolecules. The biotin-grafted nanotubes are capable of interacting with epoxy groups in presence of streptavidin molecules by which chemical bridges between BF-SWCNTs and epoxy matrix are formed. The biomolecules grafted to the nanotubes surface not only facilitate the load transfer, but also improve the nanotube dispersion into the epoxy matrix, as observed by optical imaging and scanning electron microscopy. Mechanical characterization on the nanocomposite microfibers demonstrates considerable enhancement in both strength (by 76%) and modulus (by 93%) with the addition of only 1 wt.% of BF-SWCNTs. The electrical measurements reveal a clear change in electrical conductivity of nanocomposite microfibers reinforced with 1 wt.% of BF-SWCNTs in comparison to the microfibers containing solely purified carbon nanotubes. These multifunctional nanocomposite materials could be used to fabricate macro and microstructures for a wide variety of applications such as high strength polymer nanocomposite and potential easily-manipulated biosensors.  相似文献   
6.
The technology to control the interface charge density between CdTe substrates and CdTe epilayers grown by metalorganic chemical vapor deposition is studied. The interface charge is determined by the modified built-in potential derived from capacitance-voltage characteristics of Schottky contacts formed on the epilayers. Novel ultraviolet (UV) photon assisted and photo thermal surface pretreatments that control the interface between p-type CdTe substrates and CdTe epilayers are reported. The substrates are exposed to UV radiation provided by a high pressure Hg lamp operating at 600 W with a wide emission spectrum between 190 and 300 nm. The UV photon assisted surface pretreatment with hydrogen is compared with additional surface pretreatments: thermal pretreatment with hydrogen (without UV photons) and UV photo thermal pretreatment with hydrogen. The UV photon assisted and the UV photo thermal surface pretreatments with hydrogen reduce the interface charge density to a practically negligible value. In addition, the p-type doping level of the substrate is reduced considerably in a layer of few microns adjacent to the interface.  相似文献   
7.
采用水基溶液法制备铟镓锌氧化物薄膜晶体管(IGZO-TFT),研究了在有无紫外光辅助退火条件下,不同后退火温度(270,300,330,360和400℃)对IGZO-TFT器件电学性能的影响。研究发现,IGZO-TFT在后退火温度为360℃时器件电学性能最佳,从而证明了水基溶液法在小于400℃的低温下可以制备IGZO-TFT。同时,研究表明,在后退火温度为360℃时,与无紫外光辅助退火IGZO-TFT相比,经紫外光辅助退火IGZO-TFT的饱和迁移率从1.19cm^(2)/Vs增加到1.62cm^(2)/Vs,正栅偏压偏移量从8.7 V降低至4.6 V,负栅偏压偏移量从-9.7 V降低至-4.4 V,从而证明了紫外光辅助退火对IGZO薄膜具有激活与钝化作用,可以优化IGZO-TFT器件的电学性能。  相似文献   
8.
ABSTRACT: We synthesized a series of epoxysiloxane oligomers with controllable viscosity and polarity, and developed upon them a thermal-curable nanoimprint resist that was crosslinked in air at 110 oC within 30 seconds if pre-exposed to ultraviolet (UV) light. The oligomers were designed and synthesized via hydrosilylation of 4-vinyl-cyclohexane-1,2-epoxide with poly(methylhydrosiloxane) with tunable viscosity, polarity and crosslinking density. The resist exhibits excellent chemical and physical properties such as insensitivity toward oxygen, strong mechanical strength and high etching resistance. Using this resist, nanoscale patterns of different geometries with feature sizes as small as 30 nm were fabricated via a nanoimprint process based on UV-assisted thermal curing. The curing time for the resist was on the order of 10s of seconds at a moderate temperature with the help of UV light pre-exposure. This fast thermal curing speed was attributed to the large number of active cations generated upon UV exposure that facilitated the thermal polymerization process.  相似文献   
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