磁芯负载离子液体凝胶微球的制备、表征及在固定化细胞技术中的应用

选取具有良好生物相容性的壳聚糖(CS)包覆四氧化三铁纳米粒子(Fe₃O₄/CS)作为磁响应材料, 制备了磁芯负载1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF₆)凝胶微球; 对Fe₃O₄/CS及磁芯负载离子液体凝胶微球的组成、 结构、 微观形貌和磁性能进行了表征; 将其应用于固定化细胞技术, 在产紫青霉细胞全细胞生物催化甘草酸(GL)合成单葡萄糖醛酸基甘草次酸(GAMG)体系中, 实现了对全细胞生物催化剂和离子液体的快速回收和重复利用. 实验结果表明, 壳聚糖成功包裹Fe₃O₄纳米粒子; Fe₃O₄/CS均匀分布在凝胶微球内部, 并显示出良好的磁性能; 与凝胶微球固定化细胞催化体系相比, 磁芯负载[BMIM]PF₆凝胶微球固定化细胞催化体系中GAMG的产率提高了13.8%; 重复利用实验结果表明, 磁芯负载[BMIM]PF₆凝胶微球固定化产紫青霉细胞在外加磁场的作用下, 易于快速回收, 并且循环再利用9次后相对活性仍保留59.2%.     

化学学科核心素养视角下的中考化学实验探究试题分析

从化学学科核心素养的视角,结合初、高中教学内容和教学方法的衔接,分析成都市近年的中考实验探究题的特点。提出基于化学学科核心素养培养的初中化学教学建议。     

基于发展学生化学核心素养的教学设计——以“沉淀溶解平衡”为例

为了促进学生化学学科核心素养的形成和发展,构建了基于高中化学学科核心素养的教学设计基本思路,提出了4个方面的教学策略：设计教学单元,整体规划素养发展路径;制订教-学-评目标,监测素养达成;设置活动任务,承载素养的发展;创设真实情境,联结素养与知识。并以“沉淀溶解平衡”为主题教学单元进行教学设计,将基于核心素养发展的教学设计思路付诸应用,促进化学核心素养培养目标的达成。     

高中生化学学科核心素养影响因素研究

运用自编“高中生化学学科核心素养现状调查问卷”对湖北省范围内16个市（自治州）4类学校的36519名高中生首次进行大规模化学学科核心素养调查。结果表明：高中生化学学科核心素养总体表现良好,其中宏观辨识与微观探析素养水平最高,证据推理与模型认知素养水平最低;男生的化学学科核心素养及其5个维度上的表现均显著高于女生;高中生的个人维度为首要影响因素,其次为学校维度,家庭维度总体虽然影响程度不大,但是家庭经济状况对其化学学科核心素养具有较大影响;化学学习策略、化学学习动机、化学学习适应性对高中生化学学科核心素养及其5个维度具有显著正向预测作用,为强影响因素;湖北省骨干教师及市县高中化学学科教研员预测的影响化学学科核心素养因素的排序结果与实际学生调查结果存在差异。     

基于CCITIAS的专家型化学教师实验课堂行为个案研究

以化学课堂及信息技术的互动分析编码系统（CCITIAS）为研究工具,对专家型化学教师的一节实验课堂的教学行为进行分析研究。发现专家型化学教师在课堂中灵活运用多种行为组合,促进师生高效语言互动,凸显课堂“留白”艺术,创设“时空化”实验课堂。     

Measurements of Rayleigh–Taylor instability growth of laser-shocked iron–silicon alloy

The Rayleigh–Taylor (RT) instability of liquid iron alloys is important for understanding the core formation mechanism in the Earth. Here we first report the measurement of RT instability growth for a liquid iron–silicon (Fe–Si) alloy, which is one of the major candidate for the material of the Earth’s core, using a high power laser. We optimized the measurement setup and analytical technique to observe the growth of perturbation on an Fe–Si sample surface. The growth of perturbation amplitude on the Fe–Si alloy under high pressure and temperature was successfully observed using in situ X-ray radiography. The growth rate of the RT instability for the Fe–Si alloy on about 1000?GPa was estimated to be 0.3 ns^?1.     

基于可见光谱通道的松树年轮参数获取方法研究

年轮参数是树木生长的重要指标。目前年轮的检测方法主要有人工测量法、扫描仪法和X射线法等。这些方法费时费力、检测成本高、操作难度大。为此,提出采用可见光谱进行年轮参数检测的新方法。首先针对活立木年轮检测需求,设计了木芯专用可见光谱分析装置。装置采用宽光谱对称式光源,封闭式暗箱设计,彩色CCD外置、固定距离采集方式。进而采集样品全彩色图像,分别提取不同光谱通道数据进行分析,最终获得年轮特征光谱参数。以从松树活立木钻取的木芯为例,经打磨后的木芯水平固定于载物台,光源均匀照射样品,CCD采集木芯漫反射RGB图像,基于对木芯全彩色图像的不同光谱通道的分析,分别提取RGB三帧灰度图像的强度曲线,区分早晚材分界线,得到树木年轮各项指标,实现树木年轮参数的快速提取。实验首先将CCD采集的RGB图像转换至NTSC色彩空间,以扩大色彩域。在设置滤波窗滤除背景,截取出木芯图像后,通过提取木芯图像的R,G和B三灰度分量图像,发现木芯B灰度图的早晚材区域差异最分明。基于该特征,可提取出早晚材分界线的位置信息。对木芯B灰度分量图微分,得到灰度沿水平方向的空间梯度。确定灰度变化率极大值对应的各点,鉴于木芯生长特性,灰度变化率极大值对应空间位置首先取为窄像素区域,进而在窄像素区域取中间值,此即木芯年轮各早晚材的中心点。其中,早材中心点对应光谱曲线的极大值,晚材中心点对应光谱曲线的极小值。结合专家经验,建立早晚材中心点与分界线的灰度关系,可得各分界线的位置。通过早晚材分界线与年轮各参数的关系,可进一步得出年轮各项指标。对比3位林木育种专家人工识别结果,本方法检测结果除了在木芯靠近端点处的位置外,都具有极高的准确度。采用可见光谱通道的数据采集与分析方法检测树木年轮参数,检测过程可实现全自动,高效、无损,精度可达到0.1 mm,结果精确。相比于人工测量法、扫描仪法,检测效率更高;相比于X射线法,检测过程更加安全、低耗,操作更方便。是一种具有较强应用性的方法。     

Experimental modeling of percolation of molten iron through polycrystalline olivine matrix at 2.0–5.5 GPa and 1600°C

The present work was aimed to understand the role of light elements for the penetration of Fe melt through the olivine matrix at high P–T parameters. We studied the mechanism of Fe melt percolation through the olivine matrix, whose interstices are filled with carbon and sulfur. The experiments were performed using a ‘split-sphere’ type multi-anvil high pressure apparatus at pressures 2.0 and 5.5?GPa and a temperature of 1600°C. It was demonstrated that the Fe melt penetrated through the olivine matrix at a relatively high rates in the presence of carbon or sulfur in the interstices. The percolation occurs due to fast dissolution of the light elements into Fe melt and filling of these interstices by the melt.     

Influence of the core‐hole effect on optical properties of magnesium oxide (MgO) near the Mg L‐edge region

The influence of the core‐hole effect on optical properties of magnesium oxide (MgO) is established through experimental determination of optical constants and first‐principles density functional theory studies. Optical constants (δ and β) of MgO thin film are measured in the spectral region 40–300 eV using reflectance spectroscopy techniques at the Indus‐1 synchrotron radiation source. The obtained optical constants show strong core exciton features near the Mg L‐edge region, causing significant mismatch with Henke's tabulated values. On comparing the experimentally obtained optical constants with Henke's tabulated values, an edge shift of ～3.0 eV is also observed. Distinct evidence of effects of core exciton on optical constants (δ and β) in the near Mg L‐edge absorption spectra are confirmed through first‐principles simulations.     

Finite lifetime broadening of calculated X‐ray absorption spectra: possible artefacts close to the edge

X‐ray absorption spectra calculated within an effective one‐electron approach have to be broadened to account for the finite lifetime of the core hole. For methods based on Green's function this can be achieved either by adding a small imaginary part to the energy or by convoluting the spectra on the real axis with a Lorentzian. By analyzing the Fe K‐ and L_2,3‐edge spectra it is demonstrated that these procedures lead to identical results only for energies higher than a few core‐level widths above the absorption edge. For energies close to the edge, spurious spectral features may appear if too much weight is put on broadening via the imaginary energy component. Special care should be taken for dichroic spectra at edges which comprise several exchange‐split core levels, such as the L₃‐edge of 3d transition metals.