超灵敏检漏的实时校准

超灵敏检漏的实时校准是国际上尚未解决且未标准化的一个难题,本文利用自建的微流量参考漏率系统对商用检漏仪和超灵敏检漏系统进行了实时校准的实验研究,在10-14Pa.m3/s~10-10Pa.m3/s宽范围漏率内实现了对检漏仪器的实时校准。     

Rapid, Sensitive Detection of Neurotransmitters at Microelectrodes Modified with Self-assembled SWCNT Forests

Carbon nanotube (CNT) modification of microelectrodes can result in increased sensitivity without compromising time response. However, dip coating CNTs is not very reproducible and the CNTs tend to lay flat on the electrode surface which limits access to the electroactive sites on the ends. In this study, aligned CNT forests were formed using a chemical self-assembly method, which resulted in more exposed CNT ends to the analyte. Shortened, carboxylic acid functionalized single-walled CNTs were assembled from a dimethylformamide (DMF) suspension onto a carbon-fiber disk microelectrode modified with a thin iron hydroxide-decorated Nafion film. The modified electrodes were highly sensitive, with 36-fold higher oxidation currents for dopamine using fast-scan cyclic voltammetry than bare electrodes and 34-fold more current than electrodes dipped in CNTs. The limit of detection (LOD) for dopamine was 17 ± 3 nM at a 10 Hz repetition rate and 65 ± 7 nM at 90 Hz. The LOD at 90 Hz was the same as a bare electrode at 10 Hz, allowing a 9-fold increase in temporal resolution without a decrease in sensitivity. Similar increases were observed for other cationic catecholamine neurotransmitters, and the increases in current were greater than for anionic interferents such as ascorbic acid and 3,4-dihydroxyphenylacetic acid (DOPAC). The CNT forest electrodes had high sensitivity at 90 Hz repetition rate when stimulated dopamine release was measured in Drosophila . The sensitivity, temporal resolution, and spatial resolution of these CNT forest modified disk electrodes facilitate enhanced electrochemical measurements of neurotransmitter release in vivo.     

Development of xMAP Assay for Detection of Six Protein Toxins

xMAP technology was used for simultaneous identification of six protein toxins (staphylococcal enterotoxins A and B, cholera toxin, ricin, botulinum toxin A, and heat labile toxin of E. coli). Monoclonal antibody-conjugated xMAP microspheres and biotinilated monoclonal antibodies were used to detect the toxins in a sandwich immunoassay format. The detection limits were found to be 0.01 ng/mL for staphylococcal enterotoxin A, cholera toxin, botulinum toxin A, and ricin in model buffer (PBS-BSA) and 0.1 ng/mL for staphylococcal enterotoxin B and LT. In a complex matrix, such as cow milk, the limits of detection for staphylococcal enterotoxins A and B, cholera toxin, botulinum toxin A, and ricin increased 2- to 5-fold, while for LT the detection limit increased 30-fold in comparison with the same analysis in PBS-BSA. In the both PBS-BSA and milk samples, the xMAP test system was 3-200 times (depending on the toxin) more sensitive than ELISA systems with the same pairs of monoclonal antibodies used. The time required for a simultaneous analysis of six toxins using the xMAP system did not exceed the time required for ELISA to analyze one toxin. In the future, the assay may be used in clinical diagnostics and for food and environmental monitoring.     

基于敏感区域多结构元素形态学边缘检测算法

在边缘检测算法的应用中,很难同时兼顾图像处理效果和处理速度,为此,提出了一种新的边缘检测算法,将边缘处理集中在感兴趣的图像区域中.该算法利用梯度算子获得图像中的敏感区域,再构造多种结构元素,结合形态学梯度和OTSU分割法检测敏感区域的边缘.应用于沥青路面裂缝图像检测,实验结果表明,与其它边缘检测算法相比,该算法不仅具有很好的边缘提取能力,而且具有很强的抗噪能力.在保证处理效果的同时,也保证了处理速度,有很高的实用性和推广性.     

An Intensity-Stabilized Diode-Laser Spectrometer for Sensitive Detection of NH3

This paper reports on a compact analyzer for ammonia monitoring in the air based on near-infrared wavelength-modulation diode-laser absorption spectroscopy. Particular attention is devoted to the problem of residual amplitude modulation (RAM), which is responsible for the occurrence of the line profiles' distortions. The RAM effects are eliminated by means of an intensity-control feedback loop based on an acoustooptic modulator. This offers the advantage of simplifying enormously the spectral-analysis procedure, which, otherwise, would require a considerable amount of calculation if the RAM distortions were considered     

New Nanoplatform based on Upconversion Nanoparticles for Sensitive Detection of Acute promyelocytic Leukemia

正Acute promyelocytic leukemia(APL)is a special leukemia accounting for above 10%of adult acute myeloid leukemia.The t(15;17)(q22;q21)is a specific chromosome reciprocal translocation of APL,resulting in the generation of a fusion gene between a retinoic acid receptor alpha(RARα)and promyelocytic leukemia(PML)at the molecular level.Many research demonstrate that PML/RARa fusion gene can be regarded as the     

对Cu~(2+)兼具检测及分离功能的聚氨酯泡沫的制备与性能

制备了对Cu~(2+)具有高灵敏检测及分离回收功能的聚氨酯泡沫。首先采用荧光前驱体4-溴-1,8-萘二甲酸酐、乙醇胺和2-氨基-4-噻唑乙酸作为原料合成含有羟基和噻唑乙酸基团的小分子传感器N-乙醇-4-(4-噻唑乙酸)-1,8-萘二甲酰亚胺(ETN);再通过其上的羟基与甲苯-2,4-二异氰酸酯(TDI)的-NCO基团反应将小分子感应器化学链接到多孔的聚氨酯泡沫上。荧光分析表明接有小分子感应器ETN的聚氨酯泡沫吸附Cu~(2+)离子后会发出荧光,荧光强度随Cu~(2+)离子浓度增加而变强。当Cu~(2+)离子的浓度低到10-7 mol/L数量级时也可检测到荧光。而且,多孔聚氨酯泡沫(当含1%的ETN)便具有37.66mg/g回收Cu~(2+)离子的能力,这使其具有在诸如废水和污水检测和分离Cu~(2+)的潜能和价值。     

Exponential stabilization of nonlinear uncertain systems with time-varying delay

The problem of robust exponential stabilization for dynamical nonlinear systems with uncertainties and time-varying delay is investigated. Based on the Razumikhin theorem and the Lyapunov function method, the continuous state feedback controllers for the studied systems are proposed and the robust exponential stabilization criterion is established in terms of solutions to the standard Riccati differential equations. Furthermore, a delay-dependent stabilization criterion is derived in terms of a linear matrix inequality and the restriction on the derivative of the delay function is removed. Finally, two numerical examples are presented to demonstrate the validity of the proposed method.     

变时滞随机微分方程的指数稳定性

通过构建李雅普偌夫函数和利用半鞅收敛定理,对一类随机变时滞微分方程的全局指数稳定进行了分析,提出了易于判定随机变时滞微分方程几乎必然指数稳定件新的代数判据,推广了现有文献中的主要结论,并给出实例加以验证。     

Exponential growth of LBL films with incorporated inorganic sheets

The fastest growth pattern of layer-by-layer (LBL) assembled films is exponential LBL (e-LBL), which has both fundamental and practical importance. It is associated with "in-and-out" diffusion of flexible polymers and thus was considered to be impossible for films containing clay sheets with strong barrier function, preventing diffusion. Here, we demonstrate that e-LBL for inorganic sheets is possible in a complex tricomponent film of poly(ethyleneimine) (PEI), poly(acrylic acid) (PAA), and Na(+)-montmorillonite (MTM). This system displayed clear e-LBL patterns in terms of both initial accumulation of materials and unusually thick individual bilayers later in the deposition process with film thicknesses reaching 200 microm for films composed of 200 pairs of layers. Successful incorporation of MTM layers was observed by scanning electron microscopy and thermo-gravimetric analysis. Surprisingly, the growth rate was found to be nearly identical in films with and without clay layers, which suggests fast permeation/reptation of polyelectrolytes between the nanosheets during the "in-and-out" diffusion of polymer. In considering these findings, e-LBL growth property is expected for a wide array of available inorganic nanoscale components and have a potential to greatly expand the e-LBL field and LBL field altogether. The large thickness and rapid growth of the films affords fast preparation of nanostructured materials which is essential for multiple practical applications ranging from optical devices to ultrastrong composites.     

Pulsed UV Laser-Induced Stationary Capillary Vibration for Highly Sensitive and Direct Detection of Capillary Electrophoresis

A stationary wave of the capillary vibration effect was successfully induced by a series of short laser pulses. This wave could be applied to highly sensitive detection of capillary electrophoresis as well as the already reported capillary vibration induced by an intensity-modulated CW laser (CVL effect). Generally, pulses with much shorter width than the period of the natural frequency of the vibrating system cannot induce a standing vibration. However, utilizing the time constant of CVL determined by heat dissipation time, we found conditions which could induce a stable stationary wave of the capillary by a series of nanosecond light pulses. We used the KrF excimer laser operated at 248 nm with a pulse width of 60 ns and output of ～10 μJ/pulse as the CVL excitation source and applied it to highly sensitive detection of nonderivatized amino acids at the femtomole level. The sensitivity was at least 2 orders of magnitude superior to that of a commercially available UV absorbance detector. This technique extends the CVL's spectral regions. For example, in the UV region, where many biological materials have significant absorption bands, this technique will extend analytical applications in capillary electrophoresis by eliminating the need for a derivatization process.     

Sensitive Chemical Optic Sensor Using Birefringent Porous Glass for the Detection of Volatile Organic Compounds

A simple design involving a birefringent porous glass oriented between two crossed polarizers serves as the foundation for an optically based sensitive broad-spectrum chemical sensor. Volatile organic compounds (VOCs) such as acetonitrile vapors can be readily detected at concentrations of as low as 50 ppm. Changes are observed in polarized light transmitted by the anisotropic porous material constituting the sensor, upon exposure to VOC-bearing air, as intensity changes at a defined wavelength or as changes in spectral content (color) detectable by the eye. The optical effects resulting from exposure to various vapors are reversible and may result from adsorption of solvent vapors with attendant reduction of anisotropy. The microporous structure as well as the surface chemistry of the sensor may be controlled for tuning the response to VOCs for industrial applications. Miniaturization of the sensor using low-cost materials such as plastic or glass optical fibers, Polaroid films, and birefringent porous glass is demonstrated. The sensor described in this paper could use ambient light as source and the eye as detector (color change) or electronically controlled light emission and detection for better sensitivity and real time monitoring of VOCs. Such intrinsic explosion proof sensors could be used to safely monitor VOC levels in remote environments.     

一类具有Markovian参数的随机微分时滞方程的指数稳定性

对Hilbert空间中具有Markovian参数的随机泛函微分时滞方程的指数稳定性进行了讨论。利用指数鞅公式,Lyapunov函数和一些不等式给出系统指数稳定的充分条件。这是对已有结果的完善和推广。通过一个例了对本文的结论进行了说明。     

Equation of State for a Liquid with Double Exponential Potential

High Temperature - We propose a simple method for the approximation of the integrand in the integral representation of the free energy of a system of particles with two-particle interactions...     

随机时滞反应扩散神经网络的指数稳定性

本文是讨论了一类随机变时滞反应扩散Hopfield神经网络的矩指数稳定性。利用平均Lya- punov泛函方法,随机偏微分方程的Ito公式和时滞微分不等式技巧,证明了随机变时滞反应扩散Hopfield神经网络的平衡解的矩指数稳定性,给出了这类随机变时滞神经网络平衡解矩指数稳定性的实用代数判据,得到了一些新结果。最后,给出了主要定理的一个应用实例。     

变时延细胞神经网络模型的全局指数稳定性

利用Brouwer不动点定理,推广的Halanay时延微分不等式,以及Dini导数,讨论具有可变时延的细胞神经网络平衡态的存在性和全局指数稳定性,在输出函数较一般的条件下,得到了非常简单实用的差．判别条件。     

一类具指数函数系数的非线性复差分方程

众所周知,在复微分方程和复差分方程领域中,Malmquist型方程是比Painlev′e方程和Riccati方程形式更一般的非线性方程.在本文中,我们运用Nevanlinna理论的差分模拟结果和微分域理论对一类具指数函数系数的Malmquist型复差分方程进行了研究.当上述Malmquist型复差分方程的有限级超越亚纯解具有较少的零点和极点时,我们得到其增长性和指数函数ez的增长性一致.该结果是对复微分Malmquist定理和复差分Malmquist定理的推广和补充.     

具有时变时滞的模糊细胞神经网络的指数同步(英文)

我们考虑一类耦合时变时滞模糊细胞神经网络的全局指数同步性问题.利用M-矩阵方法,在较弱的条件下获得耦合时变时滞模糊细胞神经网同步的充分条件.我们的结论去掉了对时变时滞函数可导的限制,因而具有更广的应用范围.最后并通过数值例子验证了我们结论的有效性.