Real-time and label-free detection of biomolecular interactions by oblique-incidence reflectivity difference method

We successfully conduct the label-free and real-time detection of the interactions between epoxy groups and rabbit IgG and 5' CTT CAG GTC ATG AGC CTG AT 3' oligonucleotide, and between the hybridization of 5' CTT CAG GTC ATG AGC CTG AT 3' and its complementary 3' GAA GTC CAG TAC TCG GAC TA 5' oligonucleotide, by the oblique-incidence reflectivity difference (OI-RD) method. The dynamic curves of OI-RD signals, corresponding to the kinetic processes of biomolecular combination or hybridization, are acquired. In our case, the combination of epoxy groups with rabbit IgG and 5' CTT CAG GTC ATG AGC CTG AT 3' oligonucleotide need almost one and a half hours and about two hundred seconds, respectively; and the hybridization of the two oligonucleotides needs about five hundred seconds. The experimental results show that the OI-RD is a promising method for the real-time and label-free detection of biomolecular interactions.     

Structures of Pt clusters on graphene doped with nitrogen, boron, and silicon: a theoretical study

The structures of Pt clusters on nitrogen-,boron-,silicon-doped graphenes are theoretically studied using densityfunctional theory.These dopants(nitrogen,boron and silicon) each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form.The formation energy of the silicon-graphene system is lower than those of the nitrogen-,boron-doped graphenes,indicating that the silicon atom is easier to incorporate into the graphene.All the substitutional impurities enhance the interaction between the Pt atom and the graphene.The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen-and boron-doped graphenes.The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size.The stable structures of Pt clusters on the doped-graphenes are dimeric,triangle and tetrahedron with the increase of the Pt coverage.Of all the studied structures,the tetrahedron is the most stable cluster which has the least influence on the planar surface of doped-graphene.     

Fabrication of CuO/T-ZnOw nanocomposites using photo-deposition and their photocatalytic property

CuO/tetrapod-like ZnO whisker (T-ZnOw) nanocomposites were successfully synthesized using a simple photo-deposition method. Some nanocomposites exhibit remarkably improved photocatalytic property, while the extents of the improvements vary with different Cu/Zn molar ratios and polyethylene glycol (PEG) concentrations. Moreover, it is found that excessively high Cu/Zn molar ratio or PEG concentration would reduce the photocatalytic property of the nanocomposites. A direct relationship between the morphology and the photocatalytic property of CuO/T-ZnOw was established and then analyzed by discussing the photocatalytic mechanism of the CuO/T-ZnOw nanocomposites.     

Conditional spin squeezing of a large ensemble via the vacuum Rabi splitting

We use the vacuum Rabi splitting to perform quantum nondemolition measurements that prepare a conditionally spin squeezed state of a collective atomic psuedospin. We infer a 3.4(6) dB improvement in quantum phase estimation relative to the standard quantum limit for a coherent spin state composed of uncorrelated atoms. The measured collective spin is composed of the two-level clock states of nearly 10(6) (87)Rb atoms confined inside a low finesse F=710 optical cavity. This technique may improve atomic sensor precision and/or bandwidth, and may lead to more precise tests of fundamental physics.     

40 Gb/s, secure optical communication based upon fast reconfigurable time domain spectral phase en/decoding with 40 Gchip/s optical code and symbol overlapping

We propose and experimentally demonstrate a 40 Gb/s secure optical communication system with on-off-keying (OOK) modulation format by using a time domain spectral phase en/decoding scheme, which employs a highly dispersive element and high-speed phase modulator for introducing significant symbol overlapping for both the encoded and incorrectly decoded noiselike signals to enhance the information security against eavesdropping using a power detector. The influence of dispersion and chip modulation rate on the symbol overlapping of the incorrectly decoded signal has been analytically investigated and experimentally verified. Security enhancement for 40 Gb/s OOK data using fast reconfigurable 40 Gchip/s optical codes with code lengths of up to 1024 has been demonstrated and compared with a 10 Gb/s system.     

基于束流位置探测器的束团长度测量

分析了驱动电子束团的频域特性,研究了基于该特性进行长度测量的理论基础;使用三维模拟软件对束流位置探测器(BPM)进行建模,用模拟的方法对传输阻抗进行了数值计算;对不同长度的束团进行了测量和计算,并且分析了束团位置在真空管道中偏移对束团长度测量的影响。由测量结果可见,电子束团长度在10~100 ps(3~30 mm)时,测量误差均小于2%,满足中国工程物理研究院高平均功率自由电子激光太赫兹实验测量的使用要求。     

金属Bi的卸载熔化实验研究

在火炮上利用金属铋(Bi)直接撞击单晶LiF窗口, 开展了金属Bi反向碰撞的冲击加载-卸载实验研究, 实验采用激光位移干涉测试系统, 获得了金属Bi在11—16 GPa压力范围内完整的卸载粒子速度剖面. 实验结果结合特征线方法计算表明, 金属Bi经冲击加载进入体心立方相, 并在11—16 GPa冲击压力作用下发生了卸载熔化, 界面粒子速度剖面的卸载拐点, 对应着金属Bi经冲击加载后发生的卸载熔化, 而这一结论同Cox的理论计算及一维流体力学程序计算结果基本一致. 本文报道的金属Bi卸载波剖面解读技术, 对于认识冲击加载下其他相似材料相变具有实用价值.     

Addition of multiwalled carbon nanotube and graphene nanosheet in cobalt oxide film for enhancement of capacitance in electrochemical capacitors

In order to enhance the capacitance of electrochemical capacitors, multiwalled carbon nanotubes (MWCNTs) and graphene nanosheets (GNS) were added to cobalt oxide (Co₃O₄) paste. The composite film based on Co₃O₄/MWCNT/GNS (95:4:1 wt%) exhibited a capacitance of 294 F/g while the capacitance of Co₃O₄/MWCNT (95:5 wt%) and pure Co₃O₄ film is 205 and 163 F/g, respectively. The enhanced capacitance of Co₃O₄/MWCNT/GNS composite film was attributed to the electrochemical contributions of the Co₃O₄ nanoparticle attached to the GNS as well as their significantly increased specific surface areas by MWCNTs. Furthermore, the composite films showed faradaic redox capacitive behavior to double-layer capacitive behavior due to the different nanostructures of the composites.     

Size effects on tensile and fatigue behaviour of polycrystalline metal foils at the micrometer scale

Tensile and fatigue properties of as-rolled and annealed polycrystalline Cu foils with different thicknesses at the micrometer scale were investigated. Uniaxial tensile testing results showed that with decreasing foil thickness the uniform elongation decreases for both as-rolled and annealed foils, whereas the yield strength and ultimate tensile strength increase for as-rolled foils, but decrease for the annealed foils. For both the as-rolled or annealed foils, bending fatigue resistance decreases with decreasing the foil thickness. Deformation and fatigue damage behaviour of the free-standing foils were characterised as a function of foil thickness. In addition, the fatigue strength of various small-scale Cu foils was compared to understand the physical mechanisms of size effects on mechanical properties of the metallic material at micrometer scales.     

Hybrid Deconvolution of Adaptive Optics Retinal Images from Wavefront Sensing

Adaptive optics can be used to compensate for the wave aberration of the human eyes to achieve high-resolution imaging in real time. However the correction ＆ partial due to the limitation of hardware. We propose a kind of hybrid image post-processing method, which uses the blind deconvolution combined with the residual data in wavefront sensor to restore the partially adaptive optics corrected retinal image. This method is applied in the image restoration of the vivid human retinal images. The results show that it is effective to improve the retinal image quality.