金纳米粒子和钼氧化物复合膜修饰电极的制备及应用 (cited: 1)

利用循环伏安法将金纳米粒子和钼氧化物共同电沉积在玻碳电极表面,制备了金纳米粒子和钼氧化物复合膜修饰电极,利用SEM和XPS研究了MoO_x/AuNPs复合膜的表面形态,并研究其修饰电极对葡萄糖的电催化氧化过程. 首次提出了阳极扫描极化反向催化伏安法,即在反向扫描过程中纯的催化氧化电流通过扣减背景电流的方法被提取出来. 显著提高电流测量灵敏度改善了信噪比. 制备的MoO_x/AuNPs复合膜修饰电极在0.01～4.0 mmol/L对葡萄糖具有线性响应,电流灵敏度为2.35 mA·L/(mmol·cm²),检测限为9.01 μmol/L(信噪比为3).     

金核-铂壳纳米修饰电极在酸性溶液中对甲醛的电催化氧化

制备了金(核)铂(壳)结构纳米粒子(Au@Pt-NPs)及其Au@Pt-NPs/PVP膜修饰电极,考察该修饰电极在酸性介质中对甲醛的电催化氧化行为,研究表明金和铂之闻存在协同催化作用.使Au@Pt纳米粒子比单独铂和金纳米粒子具有更高的催化活性.循环伏安行为显示修饰电极的氧化峰电流与溶液中甲醛浓度有良好的线性关系,线性范围为0.01-0.4mg/g、检出限为4ug/g,可作为甲醛的一种灵敏而快速的电化学检测方法.     

氧化石墨烯(GO)及复合物制备及其对汞吸附特性的研究

以石墨粉(G)为原料,通过化学方法制备了氧化石墨烯(GO)、纳米Fe_3O_4负载石墨烯复合材料(MGO)、纳米Ag颗粒修饰磁性氧化石墨烯(GO-Ag/MGO-Ag)四种吸附材料,对材料进行了表征并考察了氧化石墨烯及其复合物对烟气中汞的吸附作用。研究表明四种石墨烯基吸附剂可被成功合成和表征;GO在100-150℃时对Hg~0表现出优异的吸附性能,Ag-NPs修饰GO能有效提升吸附剂对汞的吸附能力,MGO-Ag复合吸附剂对汞的吸附能力最佳;MGOAg在150~200℃时表现出优异的汞吸附能力,在反复循环之后吸附性能几乎不变;以MGO-Ag为代表的可再生磁性石墨烯基复合吸附剂在中低温条件下对Hg~0具有优异的吸附性能,且能有效与飞灰进行分离,具有良好的工业应用前景。     

石墨烯/氧化铜纳米粒子/铜修饰电极对亚叶酸钙的电催化氧化及其分析应用

采用阳极极化的方法在铜电极表面形成氧化铜纳米粒子,然后采用循环伏安法将羧基化石墨烯电沉积到上述电极表面,成功制备了石墨烯/氧化铜纳米粒子/铜电极,用于碱性溶液中亚叶酸钙的检测.采用循环伏安法对亚叶酸钙在修饰电极上的催化氧化行为进行了研究,阳极扫描极化反向催化伏安法应用于亚叶酸钙的检测.在2.0×10^-7~2.0×10^-5 mol/L范围内,该电极显示出良好的线性关系,灵敏度为22.0 μA·μL/（μmol/cm²）,检测限达到7.6×10^-8 mol/L（S/N=3）,成功应用于实际样品的检测.     

石墨烯/聚乙烯醇/聚偏氟乙烯基纳米复合薄膜的介电性能

石墨烯由于具有良好的力学性能、高的电子传递能力以及相对较低的生产成本等优势而受到广泛关注,但现在多将其直接分散在聚合物中提高聚合物的介电性能.本工作中,制备出了还原氧化石墨烯/PVA/聚偏氟乙烯(PVDF)的三相纳米复合薄膜.首先把聚乙烯醇(PVA)和氧化石墨烯(GO)分散于二甲基亚砜(DMSO)中,得到PVA非共价键修饰的GO,再将PVDF溶于该混合液体中,通过溶液浇注以及低温加热过程得到三相纳米复合薄膜.实验结果表明,在120?C下,GO可以被热还原成还原氧化石墨烯(RGO),且可以促进PVDF的α相向β相转变.PVA修饰RGO比单纯RGO在PVDF基体中分散性要好,且使PVDF的球晶尺寸大大降低,复合薄膜的介电性能大幅提高.RGO/PVA/PVDF复合膜的渗流阈值f*_(vol)约为8.45 vol.%,在10~2Hz时RGO/PVA/PVDF复合膜的介电常数大约是纯PVDF的238倍.本工作为制备介电性能高、生产成本低、操作简单的聚合物纳米复合材料提供了一种好的方法.     

GSH诱导的金纳米棒自组装及汞离子检测

提出了一种基于金纳米棒自组装的促进和抑制检测汞离子的方法.在合适的实验条件下,当金纳米棒胶体溶液中加入还原性谷胱甘肽(GSH)时,金纳米棒因Au-S键的形成,通过氢键和静电相互作用发生头对头(End to End)的自组装.当以上体系中加入汞离子时,这种头对头的自组装会被打破,金纳米棒重新呈分散状态.这种方法的最低检测限为1nmol/L,检测范围为1nmol/L-100μmol/L.该汞离子检测方法特异性强、灵敏度高且检测的浓度范围比较大,有望广泛用于水环境中汞离子的检测.     

普鲁士蓝/壳聚糖/多壁碳纳米管修饰电极的制备及其电化学性质

制备了普鲁士蓝(PB)/壳聚糖(CS)/多壁碳纳米管(MWCNTs)修饰的玻碳电极.采用循环伏安法(CV),扫描电子显微镜、红外光谱技术对修饰电极进行表征,结果表明,PB纳米成功的修饰到电极表面,膜结构较均一,修饰量大,具有较强的空间结构性.此外,研究了不同pH值和不同扫描速率条件下PB/CS/MWCNTs修饰电极在0.1mol/L磷酸缓冲溶液中的电化学行为,结果表明该修饰电极具有良好的电化学性质,在电化学生物传感器领域具有潜在的应用价值.     

纳米硫化锌吸附剂中汞的稳定性研究

为了探究对纳米硫化锌吸附剂中汞的稳定性,采用重金属污染评价方法毒性特性浸出(TCLP)法对纳米硫化锌(Nano-ZnS)吸附的汞稳定性进行评价,并进一步研究了纳米硫化锌汞吸附量、浸提剂初始pH、浸出时间、液固比以及酸雨类型等对纳米硫化锌中汞稳定性的影响.结果表明:在偏酸性与偏碱性的条件下浸出液汞浓度较大,但是即使在pH=1与pH=13的情况下纳米硫化锌吸附的汞最大浸出浓度也仅分别为0.292μg/L与4.211μg/L。同时TCLP实验结果远低于TCLP标准中汞的安全浓度值25μg/L,说明纳米硫化锌吸附的汞具有良好的稳定性。     

非现场型红外光谱法在电化学检测己烯雌酚中的应用

建立了亚甲基蓝(MB)修饰多壁碳纳米管玻碳电极(MWNT/GCE)测定药片中己烯雌酚(DES)的方法,并采用非现场型傅里叶红外光谱技术(Off-site-FTIR)对亚甲基蓝修饰电极进行了表征检测.结果表明,聚亚甲基蓝在电极上的形成是由于双键断裂,使得在1603.3cm-1处的C＝N键伸缩振动吸收带消失;在0.2mol/L的磷酸缓冲液(pH=7.5)中,采用修饰电极己烯雌酚的伏安曲线出现特征氧化峰,峰电位为0.209V,峰电流显著提高,表现出明显的电催化作用;利用方波伏安法(Square Ware Voltammetry,SWV)测得峰电流与己烯雌酚质量浓度在1.0×10-5-1.0×10-9g/L范围内呈线性关系,线性相关系数0.9949,检出限5.0× 10-10g/L.用此法对己烯雌酚药片的含量进行了测定,测定结果与标示相符.     

离子液体掺杂聚苯胺/普鲁士蓝复合膜的高灵敏葡萄糖传感器

利用经典的循环伏安法制备出普鲁士蓝/离子液体-聚苯胺/多壁碳纳米管(PB/IL-PANI/MWNTs)复合膜．离子液体为润滑剂,能够显著增强聚苯胺链的电子去极化度并减少其链的结构缺陷．离子液 体的引入使该复合膜在H₂O₂检测中呈现出更优异的特性,线性范围为2.5～5.0 mmol/L,灵敏度为736.8 μA·(mmol/L)^-1·cm^-2,复合膜比纯PB 膜在中性溶液中稳定性好;传感器在12.5～1.75 mmol/L对葡萄糖也呈现很好的线性关系,检测限为1.1 μmol/L(信噪比为3),灵敏度为94.79 μA·(mmol/L)^-1·cm^-2．该传感器还用于检测未经过任何预处理的人血清中的血糖含量,结果和医院提供的值吻合较好．     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.