Urea Biosensor Based on Electrochromic Properties of Prussian Blue

Prussian blue (PB) is an electrochromic material, which can be used as a signal transducer in the formation of optical urea biosensors. The previous researches in electrochromic properties of PB demonstrated the optical PB response to ammonium ions, which occurs when ammonium ions are interacting with PB layer at a constant 0.2 V vs Ag|AgCl|KCl_sat potential. In this work PB optical dependence on ammonium ions concentration was applied in the formation of electrochromic urea biosensor. Biosensor was formed by modifying the optically transparent indium tin oxide (ITO) coated glass electrode (glass/ITO) with Prussian blue layer and immobilizing urease (glass/ITO/PB‐urease). Calibration curve showed the linear dependency (R²=0.995) between the change of maximal absorbance (ΔA) and urea concentration in concentration range varying from 3 mM to 30 mM. The highest sensitivity (4 ΔA M^?1) of glass/ITO/PB‐urease biosensor is in the concentration range from 7 mM to 30 mM. It was determined that working principle of the glass/ITO/PB‐urease biosensor is not related to pH changes occurring during enzymatic hydrolysis of urea.     

Multicomponent Organic Metal Halide Hybrid with White Emissions

Zero‐dimensional (0D) organic metal halide hybrids, in which organic and metal halide ions cocrystallize to form neutral species, are a promising platform for the development of multifunctional crystalline materials. Herein we report the design, synthesis, and characterization of a ternary 0D organic metal halide hybrid, (HMTA)₄PbMn_0.69Sn_0.31Br₈, in which the organic cation N‐benzylhexamethylenetetrammonium (HMTA⁺, C₁₃H₁₉N₄⁺) cocrystallizes with PbBr₄^2?, MnBr₄^2?, and SnBr₄^2?. The wide band gap of the organic cation and distinct optical characteristics of the three metal bromide anions enabled the single‐crystalline “host–guest” system to exhibit emissions from multiple “guest” metal halide species simultaneously. The combination of these emissions led to near‐perfect white emission with a photoluminescence quantum efficiency of around 73 %. Owing to distinct excitations of the three metal halide species, warm‐ to cool‐white emissions could be generated by controlling the excitation wavelength.     

Wavelet transforms in separation science for denoising and peak overlap detection

Wavelet transform is a versatile time‐frequency analysis technique, which allows localization of useful signals in time or space and separates them from noise. The detector output from any analytical instrument is mathematically equivalent to a digital image. Signals obtained in chemical separations that vary in time (e.g., high‐performance liquid chromatography) or space (e.g., planar chromatography) are amenable to wavelet analysis. This article gives an overview of wavelet analysis, and graphically explains all the relevant concepts. Continuous wavelet transform and discrete wavelet transform concepts are pictorially explained along with their chromatographic applications. An example is shown for qualitative peak overlap detection in a noisy chromatogram using continuous wavelet transform. The concept of signal decomposition, denoising, and then signal reconstruction is graphically discussed for discrete wavelet transform. All the digital filters in chromatographic instruments used today potentially broaden and distort narrow peaks. Finally, a low signal‐to‐noise ratio chromatogram is denoised using the procedure. Significant gains (>tenfold) in signal‐to‐noise ratio are shown with wavelet analysis. Peaks that were not initially visible were recovered with good accuracy. Since discrete wavelet transform denoising analysis applies to any detector used in separation science, researchers should strongly consider using wavelets for their research.     

用于原子干涉仪的拉曼光的制备

原子干涉仪是利用原子物质波的特性而实现的干涉仪,广泛应用于精密测量领域.在原子干涉仪中,通过拉曼光对原子进行相干操作,拉曼光的质量直接影响着干涉仪的技术指标.基于注入锁定技术,采用普通半导体激光器、声光调制器,实现了功率、频率和位相稳定的拉曼光的制备,并对拉曼光的相位噪声技术指标进行了测试.     

Noise-induced synchronous stochastic oscillations small scale cultured heart-cell networks

This paper reports that the synchronous integer multiple oscillations of heart-cell networks or clusters are observed in the biology experiment. The behaviour of the integer multiple rhythm is a transition between super- and sub- threshold oscillations, the stochastic mechanism of the transition is identified. The similar synchronized oscillations are theoretically reproduced in the stochastic network composed of heterogeneous cells whose behaviours are chosen as excitable or oscillatory states near a Hopf bifurcation point. The parameter regions of coupling strength and noise density that the complex oscillatory rhythms can be simulated are identified. The results show that the rhythm results from a simple stochastic alternating process between super- and sub-threshold oscillations. Studies on single heart cells forming these clusters reveal excitable or oscillatory state nearby a Hopf bifurcation point underpinning the stochastic alternation. In discussion, the results are related to some abnormal heartbeat rhythms such as the sinus arrest.     

The planar jet-plate oscillator

The aeroacoustic noise generated by a high speed, planar gas jet impinging on a flat plate is investigated experimentally. The jet used in this study is typical of those commonly found in industrial applications such as in various coating control and heat transfer processes. Normal jet impingement on the plate is found to generate strong acoustic tones over a wide range of impingement distances and jet velocities. The characteristics of these tones, as a function of the jet velocity and impingement distance, are quantified. Phase and amplitude measurements of the pressure fluctuations on the impingement plate indicate that the acoustic tones are generated by an antisymmetric instability mode of the jet oscillation. The effect of plate inclination in both the transverse and span-wise directions, with respect to the incident jet, is also studied. The jet-plate tone is found to be much more sensitive to changes in the span-wise plate inclination than to changes in the transverse inclination, but in both cases, a complete suppression of the tone is found to be possible.     

基于修正PSO-UKF的SINS/GPS组合导航滤波算法

针对噪声时变特性引起滤波精度下降的问题,提出了一种基于修正粒子群技术( PSO)的自适应UKF算法.为了克服传统粒子群算法过早收敛,容易陷入局部最优的问题,基于粒子的适应值方差提出了一种惯性权值实时修正算法,有效改善了传统PSO算法.在使用新息序列对观测噪声进行实时跟踪的同时,通过构造合理的适应度函数将修正PSO算法和...     

A class of Gaussian processes with fractional spectral measures

We study a family of stationary increment Gaussian processes, indexed by time. These processes are determined by certain measures σ (generalized spectral measures), and our focus here is on the case when the measure σ is a singular measure. We characterize the processes arising from σ when σ is in one of the classes of affine selfsimilar measures. Our analysis makes use of Kondratiev white noise spaces. With the use of a priori estimates and the Wick calculus, we extend and sharpen (see Theorem 7.1) earlier computations of Ito stochastic integration developed for the special case of stationary increment processes having absolutely continuous measures. We further obtain an associated Ito formula (see Theorem 8.1).     

C~n上Fock空间之正交补空间上的对偶Toeplitz算子的紧性

讨论C~m上Fock空间之正交补空间上以平方可积函数为符号的对偶Toeplitz算子,并给出其有界性与紧性的等价判别条件.     

2010年研究生数学建模竞赛A题综述

第七届全国研究生数学建模竞赛A题是生物信息学中的一个急需解决的问题.虽然有关问题的研究已经经历了十多年,但由于问题的复杂性,人们的认识还很局限,基本的结论大多还以定性的为主,定量的探讨正方兴未艾.对参赛队员来讲解决该问题是一个极大的挑战.研究生们在讨论该问题时,大多直接进行分类.然而对于一个小样本的学习问题,显然这样做是行不通的.所以问题的关键是从数学和生物学角度减少用于分类的特征数目.同时,对于获取的基因标签,需要从临床上或生物学角度找到验证.该问题的求解过程引导研究生们从数学建模走向解决实际问题.