Magnetic nanocomposites of Fe_3O_4/SiO_2-FITC with pH-dependent fluorescence emission

This paper describes the formation of magnetic and fluorescent nanocomposite particles which consist of superparamagnetic Fe_3O_4 core,SiO_2 shell and organic dye(FITC) coating layer on their surface.The obtained nanocomposites possess typical superparamagnetism and exhibit clear green fluorescence image.And their fluorescence emission is pH-dependent,which would be applied to pH sensing.     

Facile synthesis of gold nanoplates by thermally reducing AuCl_4~- with aniline

We herein report a one-step,wet-chemical approach to synthesizing gold nanoplates in large quantities via the AuCl_4~-thermal reduction process by aniline,without introducing additional capping agent or suffactant.It is found that the reduction kinetics of AuCl_4~-is greatly altered by varying the initial molar ratio of aniline to AuCl_4~-.Moreover,further investigation reveals that the in- situ formed polyaniline could serve effectively as a capping agent to preferably adsorb the{111}facets of gold crys...     

All-optical up-conversion for 2.5-Gb/s signals in ROF systems based on FWM effect in HNLF

We propose and demonstrate experimentally a novel scheme to realize all-optical up-conversion and wavelength-conversion based on the bi-directional-pump four-wave mixing （FWM） effect in high nonlinear fibers （HNLFs）.The pump is generated with optical carrier suppression in a Mach-Zehnder modulator.The two pumps are always parallel and phase-locked.A balance-detection photo-detector for optical signal detection is employed with 3-dB improvement in power penalty.The 2.5-Gb/s signals are transmitted successfully over the 25-km single-mode fiber in 30-GHz radio over fiber （ROF） systems.     

Heterodyne direct-detection OOFDM system with low sampling rate

A method of multi-channel receiving for high bit rate heterodyne direct-detection optical orthogonal frequency-division-multiplexing （OOFDM） system is proposed to reduce the sampling rate demand of analog-to-digital converter （ADC）. The sampling rate of ADCs can be reduced to 1/N that of the original signal bandwidth in an N-channel receiving system. Aided by a succeeding digital signal processing （DSP） at the receiver, aliasing free signal can be recovered. A back-to-back experimental result is given for a 4-channel system, based on which, a down conversion process for heterodyne can be reduced. The signal rebuilding algorithm is given and analyzed in its complexity and noise tolerance.     

SOI通道转换型多模干涉耦合器的研究

设计和制作了基于SOI的通道转换型多模干涉耦合器。用二维BPM方法分析了耦合器的性能与多模波导宽度和长度的依赖关系.制作出的耦合器能实现良好的通道转换,器件的功率转换比为73,附加损耗为2.2 dB.提高器件制作的精度将能进一步改善耦合器的性能.     

Low band-gap benzodithiophene-thienothiophenecopolymers: the effect of dual two-dimensional substitutions on optoelectronic properties

Two new conjugated copolymers,PBDT-T6-TTF and PBDT-T12-TTF,were derived from a novel 4-fluorobenzoyl thienothiophene(TTF).In addition,two types of benzodithiophene(BDT)units with 2,3-dihexylthienyl(T6)and 2,3-didodecylthienyl(T12)substituents,respectively,were successfully synthesized.The effect of the dual two-dimensional(2D)substitutions of the building blocks upon the optoelectronic properties of the polymers was investigated.Generally,the two polymers exhibited good solubility and broad absorption,showing similar optical band gaps of~1.53 e V.However,PBDT-T6-TTF with its shorter alkyl chain length possessed a larger extinction coefficient in thin solid film.The highest occupied molecular orbital(HOMO)level of PBDT-T6-TTF was located at–5.38 e V while that of PBDT-T12-TTF was at–5.51 e V.In space charge-limitedcurrent(SCLC)measurement,PBDT-T6-TTF and PBDT-T12-TTF displayed respective hole mobilities of 3.0×10–4 and1.6×10–5 cm2 V1 s1.In polymer solar cells,PBDT-T6-TTF and PBDT-T12-TTF showed respective power conversion efficiencies(PCEs)of 2.86%and 1.67%.When 1,8-diiodooctane(DIO)was used as the solvent additive,the PCE of PBDT-T6-TTF was remarkably elevated to 4.85%,but the use of DIO for the PBDT-T12-TTF-blend film resulted in a lower PCE of 0.91%.Atomic force microscopy(AFM)indicated that the superior efficiency of PBDT-T6-TTF with 3%DIO(v/v)should be related to the better continuous phase separation of the blend film.Nevertheless,the morphology of the PBDT-T12-TTF deteriorated when the 3%DIO(v/v)was added.Our results suggest that the alkyl-chain length on the 2D BDT units play an important role in determining the optoelectronic properties of dual 2D BDT-TT-based polymers.     

Using the Chiral Organophosphorus Derivatizing Agents for Determination of the Enantiomeric Composition of Chiral Carboxylic Acids by ^31PNMR Spectroscopy

The use of chiral organophosphorus derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the ^31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.     

Hetero-nanostructure of silver nanoparticles on MO_x(M=Mo,Ti and Si) and their applications

This paper reviews the recent research progress in the hetero-nanostructure of silver nanoparticles on MOx (M=Mo, Ti and Si). It describes the general synthesis of hetero-nanostructure of silver nanoparticles on MOx, and then outlines the interesting catalytic and sensing properties found in these hetero-nanostructures of silver nanoparticles on MOx.     

沉积温度、膜厚对Ce_(0.8)Gd_(0.2)O_(2-δ)薄膜的微结构和电导率影响

采用脉冲激光沉积法在MgO(100)单晶衬底上制备了Ce0.8Gd0.2O2-δ(CGO)系列薄膜,沉积温度与膜厚对CGO/MgO薄膜的微结构及离子电导率的影响分别被研究.X-ray衍射(2θ-ω线扫描,ω-摇摆曲线,(-扫描)测量显示,随着沉积温度的升高,CGO薄膜的微结构由多晶薄膜演变到外延膜.对沉积在730℃的CGO薄膜(510nm)中较大的离子电导归因于薄膜中较小的晶界密度.对高质外延的CGO薄膜(沉积730℃),随着膜厚的减小,其快速减小的激活能及增大的离子电导可解释为CGO/MgO界面平面的应变态和氧空位的无序分布所致.我们的结果表明,为获得高离子电导的CGO薄膜,最佳的沉积温度和膜厚是需要考虑的.     

Long-reach 60-GHz radio-over-fiber system based on turbo-coded OFDM

Turbo-coded 1.25-Gb/s orthogonal frequency-division multiplexing （OFDM） signals in 60-GHz radio-over-fiber system are demonstrated.It can overcome impairments in fibers and extend transmission distance.Experimental results show that the transmission distance of turbo-coded OFDM signals at 1.25 Gb/s with coding （pure bit rate of 830 Mb/s） can be extended by over 30%.