无线传感器网络安全定位研究

定位是无线传感器网络的重要支撑技术之一,保证定位的安全性对无线传感器网络的应用全关重要。文章针对安全在定位中的重要性,叙述了定位的安全需求,详细介绍了各种攻击模式和专门针对定位的攻击,对已存在的所有安全定位技术作了全面介绍和比较。最后指出当前安全定位技术存在的不足和安全定位今后的研究方向。     

在激光大气传输中利用SBS阈值效应实现小面积信标的研究

 在理论上建立起将受激布里渊散射（SBS）与激光大气传输过程相结合的激光补偿传输的数学模型,并进行了数值模拟，提出并证明了利用SBS阈值效应可以将相位共轭光会聚到目标上一个小面积上，从而在目标上主动获得小面积信标光斑。利用SBS实现激光大气补偿传输（传输距离250m）的实验研究,证实了上述理论预期。     

一种示位标信号的数字化解调方法

卫星紧急无线电示位标(简称示位标)是一种在紧急情况下向国际搜救组织卫星发射求救信号的装置.示位标发射的是一种调相信号,传统的在检测时用的示位标检测仪通常利用模拟方法对信号进行解调.采用模拟解调方法虽然原理简单但电路实现比较复杂,且对生产调试要求较高,若电路设计不合理还非常容易受到温度、电磁干扰的影响.随着近年数字器件处理能力的提高,越来越多的信号解调由数字化方式实现.本文提出的针对示位标信号的数字化相位解调方法可以采用单片机和FPGA实现,采用数字化方法进行解调具有体积小、调试简单等诸多优点.     

A versatile label-free and signal-on electrochemical biosensing platform based on triplex-forming oligonucleotide probe

Nucleic acid and protein assays are very important in modern life sciences, and the recently developed triplex-forming oligonucleotide probes provide a unique means for biological analysis of different kinds of analytes. Herein, we report a label-free and signal-on electrochemical sensor for the detection of specific targets, which is based on the triple-helix structure formation between the hairpin molecular beacon and the capture probe through the intermolecular DNA hybridization induced by Watson-Crick and Hoogsteen base pairings. Upon the introduction of a specific target, the triple-helical stem region is dissembled to liberate the hemin aptamer, and a G-quadruplex− hemin complex can be formed in the presence of K⁺ and hemin on the electrode surface to give an electrochemical response, thus signaling the presence of the target. With the use of Human Immunodeficiency Virus type 1 (HIV-1) as a proof-of-principle analyte, we first demonstrated this approach by using a molecular beacon, which consists of a central section with the DNA sequence complementary to HIV-1, flanked by two arm segments. This newly designed protocol provides an ultrasensitive electrochemical detection of HIV-1 with a limit of detection down to 0.054 nM, and also exhibit good selectivity. Therefore, the as-proposed strategy holds a great potential for early diagnosis in gene-related diseases, and with further development, it could be used as a universal protocol for the detection of various DNA sequences and may be extended for the detection of aptamer-binding molecules.     

基于GPS与Iridium9523的信标机设计

针对沙漠、戈壁等特殊环境下,飞行器飞行试验落点快速搜索问题,提出了一种基于GPS与铱星Iridium9523的信标机设计方法,利用GPS模块实时获取飞行器飞行试验过程中的位置信息,同时利用铱星的全球移动通信链路实时转发,最终将位置信息发送至地面试验人员,实现被测目标的实时定位。本文设计的信标机结构简单,功耗低,定位精度高。多次实地测试表明,该设备能够可靠的完成定位信息的获取与转发,其水平位置精度2.3米,具有良好的应用前景。     

A distributed transmit beamforming synchronization strategy for multi-element radar systems

The distributed transmit beamforming has recently been discussed as an energy-effective technique in wireless communication systems. A common ground of various techniques is that the destination node transmits a beacon signal or feedback to assist source nodes to synchronize signals. However, this approach is not appropriate for a radar system since the destination is a non-cooperative target of an unknown location. In our paper, we propose a novel synchronization strategy for a distributed multiple-element beamfoming radar system. Source nodes estimate parameters of beacon signals transmitted from others to get their local synchronization information. The channel information of the phase propagation delay is transmitted to nodes via the reflected beacon signals as well. Next, each node generates appropriate parameters to form a beamforming signal at the target. Transmit beamforming signals of all nodes will combine coherently at the target compensating for different propagation delay. We analyse the influence of the local oscillation accuracy and the parameter estimation errors on the performance of the proposed synchronization scheme. The results of numerical simulations illustrate that this synchronization scheme is effective to enable the transmit beamforming in a distributed multi-element radar system.     

分子信标用于核酸连续复制过程的体外实时监测

利用分子信标核酸探针实时监测了核酸连续复制过程. 分子信标不仅作为模板参与复制反应, 而且同步将复制过程的信息转换为荧光信号, 实现复制过程的体外实时监测. 该方法不仅为DNA复制检测提供了一种实时研究手段, 而且为核酸复制动力学及与复制相关疾病的深入研究提供了一种新的思路.     

基于锁核酸的高选择性新型分子信标

通过在分子信标的错配位点修饰锁核酸, 不仅可有效地改善其单碱基错配识别能力, 还可提高检测灵敏度. 因而有望发展成为一种通用的提高分子信标单碱基错配识别能力的方法.     

A novel sandwich assay with molecular beacon as report probe for nucleic acids detection on one-dimensional microfluidic beads array

A novel sandwich assay with molecular beacons as report probes has been developed and integrated into one-dimensional microfluidic beads array (1-D chip) to pursue a label-free and elution-free detection of DNA/mRNA targets. In contrast with the immobilized molecular beacons, this sandwich assay can offer lower fluorescence background and correspondingly higher sensitivity. Furthermore, this sandwich assay on 1-D chip operating in conjunction with molecular beacon technique allows multiple targets detection without the need of laborious and time-consuming elution, which makes the experiment process simple, easy to handle, and reproducible results. In the experiment, the synthesized DNA targets with different concentrations were detected with a detection limit of ∼0.05 nM. Moreover, the mRNA expression changes in A549 cells before and after anticancer drug 5-flouorouracil treatments were detected and the results were validated by the conventional RT-PCR method.     

A label-free, quadruplex-based functional molecular beacon (LFG4-MB) for fluorescence turn-on detection of DNA and nuclease

We demonstrate a novel concept for the construction of a label-free, quadruplex-based functional molecular beacon (LFG4-MB) by using G-quadruplex motif as a substitute for Watson-Crick base pairing in the MB stem and a specific G-quadruplex binder, N-methyl mesoporphyrin IX (NMM) as a reporter. It shows high sensitivity in assays for UDG activity/inhibition and detection of DNA sequence based on the unique fluorescence increase that occurs as a result of the strong interaction between NMM and the folded quadruplex upon removal of uracil by UDG or displacement of block sequence by target DNA. The LFG4-MB is simple in design, fast in operation and could be easily transposed to other biological relevant target analysis by simply changing the recognition portion. The LFG4-MB does not require any chemical modification for DNA, which offers the advantages of simplicity and cost efficiency and obviates the possible interference with the affinity and specificity of the MB as well as the kinetic behavior of the catalysts caused by the bulky fluorescent groups. More importantly, the LFG4-MB offers great extent of freedom to tune the experimental conditions for the general applicability in bioanalysis.