High Sensitive Microsensor Based on Organic‐Inorganic Composite for Two‐Dimensional Mapping of H2O2 by SECM

The present work describes the development of a selective, sensitive and stable sensing microsensor for scanning electrochemical microscopy (SECM) to measure H₂O₂ during electrochemical reduction of oxygen. The microsensor is based on graphene and Poly(3,4‐ethylenedioxythiophene) composite as support to iron (III) hexacyanoferrate (II) (PEDOT/graphene/Fe^III₄[Fe^II(CN)₆]₃ microsensor). The electrochemical properties of the PEDOT/graphene/Fe^III₄[Fe^II(CN)₆]₃ microsensor were investigated by cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The PEDOT/graphene/Fe^III₄[Fe^II(CN)₆]₃ microsensor showed an excellent electrocatalytic activity toward hydrogen peroxide (H₂O₂) reduction with a diminution of the overpotential of about 500 mV in comparison to the process at a bare gold microelectrode. The microsensor presented excellent performance for two dimensional mapping of H₂O₂ by SECM in 0.1 mol L^?1 phosphate buffer solution (pH 7.0). Under optimized conditions, a linear response range from 1 up to 1000 µmol L^?1 was obtained with a sensitivity of 0.08 nA L µmol^?1 and limit of detection of 0.5 µmol L^?1.     

思维导图在物理化学教学中的应用

通过介绍思维导图的特征以及思维导图软件XMind的主要功能特点,阐述了思维导图应用于物理化学的理论基础。以XMind软件作为绘制工具,以"热力学第二定律"为例,探讨了将思维导图运用于单元总结中,在建构知识体系、把握知识脉络以及训练思维能力方面的有效作用。进一步以本章重要知识点"熵增加原理"为例,尝试思维导图在知识点的理解掌握、拓展应用等方面的具体应用。     

Micro- and nano-mechanical characterization of polyamide 11 and its composites containing cellulose nanofibers

Nanocomposites from polyamide 11 and dried cellulose nanofibers (CNs), 16–30 nm in thickness and 50–400 nm in length, were prepared via direct melt mixing and their micro- and nano-mechanical properties were studied. (PF) QNM (Quantitative Nanomechanical Mapping) method was used to map nanomechanical properties at the surface of polyamide 11 and nanocomposites. This new AFM method emphasized both the increased modulus in nanocomposites as compared to the matrix and the microstructure on different levels in polyamide 11 and its nanocomposites. PF QNM showed that their crystalline structure consists of bundles of lamellar stacks, 200–350 nm in width and 20–40 nm wide lamellar stacks. Moreover, PF QNM study emphasized higher structural order in nanocomposites with 3 and 5 wt.% CNs and lower in the nanocomposite with 8 wt.% CNs as compared to the reference. These observations were verified and are consistent with both crystallinity values determined by DSC and micro-mechanical test results. The oriented bundles of lamellar stacks, observed by PF QNM, could be considered as the main blocks determining high mechanical properties for the studied nanomaterials.     

In situ detection of a single carotenoid crystal in a plant cell using Raman microspectroscopy

It is the first report of direct, in situ detection of carotenoids at the subcellular level by using Raman microspectroscopy. Single crystals sequestered in a carrot cell were measured using FT-Raman spectrometer equipped with a microscope and 40× objective. The observed characteristic bands centered at 1518 cm⁻¹ and 1156 cm⁻¹ proved the crystals were composed of carotenoids with β-carotene being predominant. The obtained results show the potential of Raman microspectroscopy for identification and analysis of compounds localized in cytoplasm by taking measurements directly from a single plant cell.     

高光谱成像的土壤剖面水分含量反演及制图

传统土壤水分的获取方法仅可获得离散的土壤水分点位数据,难以获得剖面上精细且连续的水分含量分布图。研究了野外条件下利用近红外高光谱（882～1 709 nm）成像反演剖面土壤水分含量（SMC）,并实现精细制图的可行性。研究剖面位于江苏省东台市,我们利用近红外高光谱成像仪对剖面进行了5天原位连续观测,共采集了280个土样用于烘干法测定SMC。原始高光谱图像经数字量化值（DN）校正、黑白校正、拼接、几何校正、剪切和掩膜等一系列预处理后,提取各采样点的平均光谱反射率。提取光谱（Raw）经吸光度[LOG₁₀(1/R)],Savitzky-Golay平滑（SG）、一阶微分（FD）、二阶微分（SD）、多元散射校正（MSC）和标准正态变量（SNV）转换后,采用偏最小二乘回归（PLSR）和最小二乘支持向量机（LS-SVM）方法建立SMC预测模型,并对比分析不同光谱预处理方法与建模方法组合条件下SMC的预测精度。结果表明,光谱反射率随SMC增加逐渐降低,不同光谱预处理方法的预测精度有所差异,除MSC方法外,同一光谱预处理方法的LS-SVM模型预测精度均高于PLSR模型,并且基于LOG₁₀(1/R)光谱的LS-SVM模型对SMC预测精度最高,其建模集的决定系数（R2_c）和均方根误差（RMSE_c）分别为0.96和0.65%,预测集的决定系数（R2_p）、均方根误差（RMSE_p）和相对分析误差（RPD_p）分别为0.88,1.05%和2.88。利用最优模型进行剖面SMC的高空间分辨率精细制图,通过比较SMC反演图中提取的预测值与实测值关系发现预测精度较高（R2: 0.85～0.95, RMSE: 0.94%～1.02%）,且两者在剖面中的变化趋势基本一致,说明SMC反演图不仅能很好地反映出土壤水分在整个剖面中毫米级的含量分布信息,也可反映出同一位置处不同天数间的含量差异。因此,利用近红外高光谱成像结合优化的预测模型,能够实现土壤剖面SMC的定量预测及精细制图,有助于快速、有效监测田间剖面土壤水分状况。     

矿山多源遥感图像像点位移测试系统设计

针对矿山地形的起伏变化影响对其进行分析研究的准确性,提出矿上多源遥感图像像点位移测试系统的设计方法。结合GPS定位原理,选取遥感图像上某一时刻点作为测试点,对拍摄得到的矿山图像和电子测试系统各触点之间的距离进行计算,进而得到测试点具体坐标位置,将其与测试点真实现场坐标相对比,实现矿山多源遥感图像像点位移的测试。通过实验证明,所设计的测试系统可以高精度实现对遥感图像像点位移的测试,有效减小了矿山地形变化带来的遥感图像研究误差。     

On the combined use of scratch tests and CLA profilometry for the characterization of polyester powder coatings: Influence of scratch load and speed

The prediction of the mechanical properties of polyester powder coatings is of paramount importance, as they have to undergo a wide variety of forces and deformations during their service life. Determine the response of polymeric coatings to the actual loading conditions can be, however, very troublesome as their properties are function of the material physical state, rate-dependence and yield and break behaviour. Further, the characterization of soft, contaminated organic surfaces such as polymers can often cause severe problems with reliability and imaging accuracy due to instrumental artefacts.This is therefore the context in which this paper investigates the capability of multiple parameters scratch tests joined with non-contact CLA profilometry and FE-SEM to detect the scratch response of polyester powder coatings for protective and decorative outdoor applications. Scratch tests with blunt contact geometry were used to evaluate the response of polyester coatings baked at different time-temperature programs and, so, at different stages of their curing process. In particular, being such coatings highly non-linear in their response to mechanical stress or strain, the influence from scratch load and speed was carefully taken into account. Analytical evaluations of the experimental results led to good correlations between the extent of the deformed zone after scratch, scratch parameters and curing operational settings. This allows mapping the scratch response of the polyester topcoats to broad ranges of both scratch parameters and curing conditions.     

Stabilizing the monodromy of an open book decomposition

We prove that any mapping class on a compact oriented surface with non-empty boundary can be made pseudo-Anosov and right-veering after a sequence of positive stabilizations.      

一类模糊逻辑系统幺半群与同态映射

首先利用代数中幺半群的概念给出了模糊逻辑系统专业领域的概念, 建立专业领域概念的目的是为了规范模糊逻辑系统中语言变量的取值范围, 从而将模糊逻辑系统看作是某个笛卡儿乘积幺半群的有限子集. 然后利用这个笛卡儿乘积幺半群的乘积运算构造了模糊逻辑系统幺半群. 最后, 在一定的约定条件下证明了通常使用的一类Mamdani形模糊逻辑系统的输出可以看作是从模糊逻辑系统幺半群到连续函数域的同态映射.     

Characterization of ethylene oxide–propylene oxide block copolymers by combination of different chromatographic techniques and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy

Block copolymers of ethylene oxide (EO) and propylene oxide (PO) are characterized by combination of two-dimensional chromatography and MALDI-TOF-MS. Liquid chromatography under critical conditions (LCCC) is used as first dimension and fractions are collected, mobile phase evaporated and diluted in the mobile phase used in second dimension (SEC or LAC). This two-dimensional chromatography in combination of MALDI-TOF-MS gives information about purity of reaction products, presence of the byproducts, chemical composition and molar mass distribution of all the products.