石墨烯掺杂纳米氧化锌用于检测三乙胺的增强气敏性能

通过简单研磨实现固相反应的方法制备了纳米氧化锌材料,并利用石墨烯掺杂对氧化锌进行改性,研究了氧化锌材料的气敏性能。利用X射线衍射仪(XRD)、扫描电镜(SEM)、红外光谱仪(IR)对合成的样品进行了结构和形貌表征,考察了原料比例和石墨烯掺杂量对氧化锌形貌和气敏性能的影响。结果表明:合成的氧化锌均为纳米颗粒,随着柠檬酸量增加,得到许多有气孔的氧化锌;石墨烯掺杂后,均得到纳米颗粒的氧化锌;气体检测表明,石墨烯掺杂后的氧化锌,其最佳工作温度由400℃降为280℃,对三乙胺表现出较高的选择性;掺杂3%石墨烯的氧化锌对浓度为0.1 mmol/L三乙胺的响应值(S=Ra/Rg)达到18,是掺杂前的4倍。石墨烯掺杂纳米ZnO可作为检测三乙胺气体的新型传感材料。     

N-Bridged Acyclic Trimeric Poly-Cyclodiphosphazanes: Highly Tuneable Cyclodiphosphazane Building Blocks

We have synthesized a completely new family of acyclic trimeric cyclodiphosphazane compounds comprising NH, NⁱPr, N^tBu and NPh bridging groups. In addition, the first NH-bridged acyclic dimeric cyclophosphazane has been produced. The trimeric species display highly tuneable characteristics so that the distance between the terminal N(H)R moieties can be readily modulated by the steric bulk present in the bridging groups (ranging from ≈6 to ≈10 Å). Moreover, these species exhibit pronounced topological changes when a weak non-bonding NH⋅⋅⋅π aryl interaction is introduced. Finally, the NH-bridged chloride binding affinities have been calculated and benchmarked along with the existing experimental data available for monomeric cyclodiphosphazanes. Our results underscore these species as promising hydrogen bond donors for supramolecular host–guest applications.     

Non-Stationary Complementary Non-Uniform Sampling (NOSCO NUS) for Fast Acquisition of Serial 2D NMR Titration Data

NMR spectroscopy offers unique benefits for ligand binding studies on isotopically labelled target proteins. These benefits include atomic resolution, direct distinction of binding sites and modes, a lowest detectable affinity limit, and function independent setup. Yet, retracing protein signal assignments from apo to holo states to derive exact dissociation constants and chemical shift perturbation amplitudes (for ligand docking and structure-based optimization) requires lengthy titration series of 2D heteronuclear correlation spectra at variable ligand concentration that may exceed the protein's lifetime and available spectrometer time. We present a novel method to overcome this critical limitation, based on non-stationary complementary non-uniform sampling (NOSCO NUS) combined with a robust particle swarm optimization algorithm. We illustrate its potential in two challenging studies with very distinct protein sizes and binding affinities, showing that NOSCO NUS can reduce measurement times by an order of magnitude to make such highly informative NMR titration studies more broadly feasible.     

Sensing cytochrome P450 1A1 activity by a resorufin-based isoform-specific fluorescent probe

Cytochrome P450 1A1 (CYP1A1), a heme-containing monooxygenase, is of particular importance for human health because of its vital roles in the metabolic activation of pro-carcinogenic compounds to the carcinogens. Deciphering the relevance of CYP1A1 to human diseases and screening of CYP1A1 modulators require reliable tool(s) for probing this key enzyme in complex biological matrices. Herein, a practical and ultrasensitive fluorescence-based assay for real-time sensing CYP1A1 activities in biological systems has been developed, via designing an isoform-specific fluorogenic sensor for CYP1A1 (CHPO). The newly developed fluorogenic substrate for CYP1A1 has been carefully investigated in terms of specificity, sensitivity, precision, quantitative linear range and the anti-interference ability. The excellent selectivity, strong anti-interference ability and fast response kinetics, making the practicability of CHPO-based CYP1A1 activity assay is better than that of most reported CYP1A1 activity assays. Furthermore, CHPO has been successfully used for imaging CYP1A1 activities in living cells and human tissues, as well as for high-throughput screening of CYP1A1 inhibitors using tissue preparations as enzyme sources. Collectively, this study provided a practical fluorogenic sensor for real-time sensing CYP1A1 in complex biological systems, which would strongly facilitate the investigations on the relevance of CYP1A1 to human diseases and promote high-throughput screening of CYP1A1 modulators for biomedical applications.     

基于LabVIEW的多点串联光纤传感系统设计

设计了一种远程多点光纤传感系统用于大范围对象测量,其结构为一个本地控制节点通过双向光纤链路串联所有远端传感节点。在本地控制节点共享光源、光电检测器等光电器件,并结合虚拟仪器实现数据处理电路;而远端传感节点仅包含敏感元件、无源光器件构成的光路,并能直接实现时分复用。以3节点系统的甲烷气体检测为例进行实验和计算,结果证明该方案能够有效工作,通过循环检测可使首个传感节点的相对误差降至0．2％以下。     

A tree-structured DFT filter bank based spectrum detector for estimation of radio channel edge frequencies in cognitive radios

Cognitive Radio (CR) aims to provide efficient spectrum utilization in spectrum scarce wireless environments. One of the key CR functionalities is the spectrum sensing, which allows CRs to monitor the electromagnetic spectrum and detect unused bands of spectrum. Wideband spectrum sensing needs to be employed for better spectrum opportunity detection and interference avoidance both in the case of commercial and military applications. Accurate sensing needs to be employed for blocker detection in commercial systems such as LTE for the design of transmit/receive path. In military radios, the challenge lies in the robust detection of the location of the center frequencies and bandwidths of individual radio channels in the wideband input signal. In this paper, an energy detector based on tree-structured discrete Fourier transform based filter bank (TDFTFB) is proposed for detecting the edges of the channels in the spectrum. The proposed method is compared with the conventional wavelets based method for complexity and performance. The design example and simulations show that the gate count resource utilization of the proposed detection scheme is 22.9% lesser than the wavelets method at the cost of a slight degradation (0.5%) in detection accuracy. Over-the-air tests performed using Universal Software Radio Peripheral 2 (USRP2) and MATLAB/SIMULINK showed that the present method is not input specific whereas the conventional wavelet based approach depends on the spectral location of the input.     

多功能复合材料结构状态感知系统

由于具有比强度和比刚度高、可设计性强等优点,先进复合材料正在逐步成为新一代民用飞机的主要结构材料。为了充分利用复合材料的优越性能,有必要研发一种与复合材料结构集成一体的多功能传感系统,以使复合材料结构可以"感觉"和"思考"自身状态。本文提出一种类似于人体神经系统的多功能传感器网络系统,将不同功能的传感器有机结合起来,并与复合材料结构永久集成于一体,用来感知结构应变、温度、湿度、气动压力等参量,并监测发生在结构上的外界撞击及内部损伤。利用这一新概念设计和制造的未来复合材料结构可以提供多种模式的综合信息,从而使之具有智能传感、环境适应等多种功能。本文同时也讨论了发展这样一种多功能结构状态感知系统所面临的挑战与有关解决途径。     

Image decoding optimization based on compressive sensing

Transform-based image codec follows the basic principle: the reconstructed quality is decided by the quantization level. Compressive sensing (CS) breaks the limit and states that sparse signals can be perfectly recovered from incomplete or even corrupted information by solving convex optimization. Under the same acquisition of images, if images are represented sparsely enough, they can be reconstructed more accurately by CS recovery than inverse transform. So, in this paper, we utilize a modified TV operator to enhance image sparse representation and reconstruction accuracy, and we acquire image information from transform coefficients corrupted by quantization noise. We can reconstruct the images by CS recovery instead of inverse transform. A CS-based JPEG decoding scheme is obtained and experimental results demonstrate that the proposed methods significantly improve the PSNR and visual quality of reconstructed images compared with original JPEG decoder.     

相位差法波前传感系统自身误差的分析及消除方法

 针对附加像差为离焦的情况,对焦面位置误差、离焦量误差、图像对准误差以及图像噪声等因素带来的波前传感误差进行了数值模拟,并给出了确定焦面位置、对准焦面图像和离焦面图像、精确计算分光比、确定离焦量以及处理图像噪声的方法。使得传感结果的均方根误差分别由0.088 8λ,0.059 0λ,0.128 4λ,4.170 6λ,0.152 6λ降为0.002 1λ,0.002 1λ,0.002 1λ,0.002 1λ,0.029 2λ。结果表明:这些方法可以有效地减小传感误差,大大提高了传感精度,为相位差法的实际应用提供了重要的技术支持。     

空间相机光学窗口热光学性能的仿真分析

 空间相机光学窗口与周围环境进行热交换,导致窗口的温度发生不均匀变化,包括整体温度水平的变化以及产生径向温差、周向温差和轴向温差。这些温度梯度将影响相机的光学系统质量。针对某相机光学窗口温度分布不均匀的特点,提出利用非顺序光路建立复杂光瞳的方法对光学窗口进行分区,在各子区域上建立温度的径向分布特征,然后将各子区域的变化再统一到整个元件中,进而评判对整个系统的影响。结果表明,新方法合理可行,温度周向不均匀分布会降低光学系统质量,并且不能完全通过离焦来补偿。