遵循认知规律优化课堂教学——以“分子”教学为例

以"分子"教学为例,剖析教学中多次让学生"画水"所包含的遵循学生认知规律的特色,并结合相关教育理论,提炼出遵循学生认知规律的一些教学策略。     

Quantitative, dynamic and noninvasive determination of skeletal muscle perfusion in mouse leg by NMR arterial spin-labeled imaging

Because mouse may relatively easily be genetically tailored to develop equivalent of human muscular diseases or to present controlled alterations of mechanisms involved in vasoregulation, it has become the prevalent species to explore such questions. However, the very small size of the animals represents a serious limitation when evaluating the functional consequences of these genetic manipulations. In this context, the recourse to arterial spin labeling (ASL) nuclear magnetic resonance (NMR) methods in which arterial water spins act as an endogenous and freely diffusible tracer of perfusion is tempting but challenging. This article shows that despite the small size of the animal, mouse muscle perfusion may be measured, at rest and in conditions of reactive hyperemia, using saturation inversion recovery sequence, a pulsed ASL variant, combined with NMR imaging. Baseline perfusion values in the mouse leg were 17+/-11 ml.min(-1).100 g(-1) (n=11) and were comparable to microsphere data from the literature. Under ischemia, leg perfusion was 1.2+/-9.3 ml.min(-1).100 g(-1) (n=11). The difference observed between basal and ischemic measurements was statistically different (P=.0001). The temporal pattern of hyperemia in mouse muscle was coherent with previously published measurements in humans and in rats. The mean peak perfusion was 62+/-24 ml.min(-1).100 g(-1) (n=6) occurring 48+/-27 s after the end of occlusion. In conclusion, this study demonstrated the ability of ASL combined to NMR imaging to quantify skeletal muscle perfusion in mice legs, both at rest and dynamically.     

FMRI connectivity analysis of acupuncture effects on the whole brain network in mild cognitive impairment patients

The increased risk for the elderly with mild cognitive impairment (MCI) to progress to Alzheimer's disease makes it an appropriate condition for investigation. While the use of acupuncture as a complementary therapeutic method for treating MCI is popular in certain parts of the world, the underlying mechanism is still elusive. We sought to investigate the acupuncture effects on the functional connectivity throughout the entire brain in MCI patients compared to healthy controls (HC). The functional magnetic resonance imaging experiment was performed with two different paradigms, namely, deep acupuncture (DA) and superficial acupuncture (SA), at acupoint KI3. We first identified regions showing abnormal functional connectivity in the MCI group compared to HC during the resting state and subsequently tested whether these regions could be modulated by acupuncture. Then, we made the comparison of MCI vs. HC to test whether there were any specific modulatory patterns in the poststimulus resting brain between the two groups. Finally, we made the comparisons of DA vs. SA in each group to test the effect of acupuncture with different needling depths. We found the temporal regions (hippocampus, thalamus, fusiform gyrus) showing abnormal functional connectivity during the resting state. These regions are implicated in memory encoding and retrieving. Furthermore, we found significant changes in functional connectivity related with the abnormal regions in MCI patients following acupuncture. Compared to HC, the correlations related with the temporal regions were enhanced in the poststimulus resting brain in MCI patients. Compared to SA, significantly increased correlations related with the temporal regions were found for the DA condition. The enhanced correlations in the memory-related brain regions following acupuncture may be related to the purported therapeutically beneficial effects of acupuncture for the treatment of MCI. The heterogeneous modulatory patterns between DA and SA may suggest that deep muscle insertion of acupuncture is necessary to achieve the appreciable clinical effect.     

促进小学生物质变化认识发展的概念建构及课堂活动建议

通过对新课标和学生认识发展规律的分析,围绕基于物体、基于物质状态、基于物质种类3个认识发展阶段建构了小学阶段物质变化涉及的具体概念,同时就如何构建促进小学生认识发展的课堂活动进行了讨论并提出了建议。     

促进学生认识素养发展的高中化学教学策略实证与反思

根据胡久华著的《化学课程与学生认识素养发展》中提及的促进学生认识素养发展的5点教学策略展开实证研究,以多个课堂教学案例进行阐述,强调发展学生认识素养的重要性,教学必须关注认识方式的建构。介绍了在教学实践过程中遇到的问题及实施的调整措施,进行有目的、有策略的学生认识素养的培养,从而建立学生终身受益的基本化学观念和认识。     

基于认知逻辑的“质量守恒定律”教学分析

以化学发展史中质量守恒定律的认知逻辑为视角,分析了学生学习质量守恒定律的认知障碍,并通过问卷测试进行了实证,提出了基于“问题解决”的教学设计建议,为有效课堂教学提供参考。     

物理化学课程内容的编排顺序：基于“学科思维-认知规律”双重视角的观察

物理化学课程内容的编排顺序是物理化学教学中的核心问题之一,教指委发布的《化学类专业化学理论教学建议内容》对其并未明文规定,经典教材对此处理各有不同。经过对比和分析不同经典教材的编排顺序差别,可以看出物理化学的学科思维和认知规律是决定编排顺序的两大原则。依据学科思维从空间、时间、体系等3个维度为物理化学课程的核心内容画出逻辑关系图,并结合认知规律提出了多种编排内容的方式。     

Metabolomic profiling of serum in the progression of Alzheimer's disease by capillary electrophoresis–mass spectrometry

There is high interest in the discovery of early diagnostic biomarkers of Alzheimer's disease, for which metabolomics exhibits a great potential. In this work, a metabolomic approach based on ultrafiltration and analysis by CE‐MS has been used to obtain representative fingerprints of polar metabolites from serum samples in order to distinguish between patients with Alzheimer's disease, mild cognitive impairment, and healthy controls. By the use of partial least squares discriminant analysis it was possible to classify patients according to the disease stage and then identify potential markers. Significant increase was observed with progression of disease in levels of choline, creatinine, asymmetric dimethyl‐arginine, homocysteine‐cysteine disulfide, phenylalanyl‐phenylalanine, and different medium chain acylcarnitines. On the other hand, asparagine, methionine, histidine, carnitine, acetyl‐spermidine, and C5‐carnitine were reduced in these serum samples. In this way, multiple essential pathways were found implicated in the underlying pathology, such as oxidative stress or defects in energy metabolism. However, the most interesting results are related to the association of several vascular risk factors with Alzheimer's disease.     

氧等离子体改性聚乙烯表面的疏水性过回复机制

用200 W射频容性耦合氧等离子体处理低密度聚乙烯(LDPE)表面1 min, 研究了老化温度及时间对LDPE表面成分、 形貌和润湿性的影响. 扫描电子显微镜结果表明, 等离子体改性LDPE表面出现纳米凸点织构, 在60和90 ℃老化24 h后纳米凸点织构特征基本保持稳定. X射线光电子能谱分析表明, 等离子体改性LDPE表面经60 ℃老化24 h后, C—C含量由76.9%增至83.0%, C—O, CO和O—CO含量分别由16.4%, 2.2%和4.5%降至13.1%, 1.9%和2.0%. 经90 ℃老化24 h后, C—C含量较60 ℃老化表面增至84.1%, C—O含量分别降至10.1%, CO和O—CO含量分别增至3.1%和2.7%. 等离子体改性LDPE表面接触角由97.2°降至42.3°, 经60 ℃老化24 h后接触角增至95.9°, 经90 ℃老化24 h后接触角增至104.2°, 等离子体改性LDPE表面发生“疏水性过回复”. 根据含有粗糙因子的接触角随时间演变模型, 得到了具有纳米凸点织构LDPE表面在不同老化温度下的可移动极性基团所占面积分数(\begin{array}{c}{f}_m^p\end{array})、 固定极性基团所占面积分数(\begin{array}{c}{f}_{\mathit{im}}^p\end{array})和特征时间常数(τ)3个成分重构参数, 解释了“疏水性过回复”现象.     

认知模型的修正与重构——以高三化学复习课“电解食盐水的再探究”为例

在高三化学复习教学中,依据对学生已有电解认知模型的调查分析,以学生已经学习过的电解饱和食盐水为探究背景,对为何用饱和食盐水、阴极为何采用铁钉等问题进行追问和探究,以破除学生对放电顺序的绝对化和唯一化的错误观念,认识到离子的放电顺序受浓度、电极材料、电压等多种因素共同的影响。对离子迁移放电电解认知模型的科学性进行追问,通过学生设计实验,分析实验现象,自主建构分析电解问题的氧化还原放电模型,以实现学生对已有的电解认知模型的修正与重构。