“乙酰水杨酸的制备和分析表征”教学实验的优化和改进

以水杨酸和乙酸酐为原料,硅胶为催化剂,利用微波技术优化改进“乙酰水杨酸的制备和分析表征”大学有机化学教学实验,通过实验探究,分析了微波功率、反应时间、原料配比等因素对最终产率的影响,得到了最佳实验条件:硅胶目数为100–200目,用量为0.25 g,反应时间60 s,反应温度70°C,微波功率500 W,乙酸酐与水杨酸的物质的量之比为2:1,平均产率约为68.0%。与常规加热情况下乙酰水杨酸的制备相比,微波辅助合成法具有操作简便、反应时间短、产品的产率高、杂质少、对环境友好等优势。将该微波实验引入大学本科生有机化学实验教学,能开阔学生视野、丰富实验教学内容,进一步提高教学水平。

“菠菜叶中色素的提取与分离”实验改进

“菠菜叶中色素的提取和分离”是大学有机化学实验课程的重要项目之一,但在教学中一直存在大量使用管制试剂、实验时间过长、实验步骤繁琐、分离效果不佳等问题。本文对菠菜叶色素分离的薄层色谱条件进行了系统探究,尝试采用了正己烷-无水乙醇、正己烷-正丁醇等多种试剂组合作为展开剂,实验结果表明最佳的展开剂是体积比为10.0:1.0的正己烷-无水乙醇。采用正己烷-无水乙醇、正己烷-正丁醇作为洗脱剂进行柱色谱分离实验,最终分别得到了以硅胶为固定相、正己烷-无水乙醇为洗脱剂的梯度洗脱方案以及以中性氧化铝为固定相、正己烷-正丁醇为洗脱剂的梯度洗脱方案。该实验方案使用更友好的试剂,试剂用量少,实验耗时短,分离效果好。

纳米WC增强Ni基涂层组织及摩擦磨损性能

为增强42CrMo钢表面硬度及耐磨性,利用半导体激光器在基体表面制备了质量分数分别为0、10%、20%、30%及40%nano-WC粉末的Ni60增强涂层。采用OM、SEM、EDS、XRD对试样的微观组织与相成分进行表征,利用数显显微硬度计和高温摩擦磨损试验机进行力学性能及摩擦磨损性能测试。结果表明,nano-WC增强Ni60涂层表面成形良好。增强涂层的组织形貌呈条状、树枝状、鱼骨状、块状和粒状;物相以奥氏体Ni-Fe相为主,nano-WC一部分保留下来,一部分形成了W2C新相;涂层中还生成有Cr23C6、M6C、Cr7C3复合碳化物及CrB和NiW等复杂化合物。nano-WC增强涂层的显微硬度最大可达1256 HV0.2,比Ni60合金涂层提高了约50%。增强涂层的最小磨损体积为1.29mm 3,仅为Ni60合金涂层的1/7;增强涂层平均摩擦系数可低至0.275,而Ni60合金涂层平均摩擦系数为0.530,降低了约48%。摩擦磨损研究表明nano-WC增强涂层磨损机制主要为黏着磨损,同时还伴有轻微的磨粒磨损。

Response of Groundwater to Climate Change under Extreme Climate Conditions in North China Plain

The North China Plain（NCP） is one of the water shortage areas of China. Lack of water resources restricted the economic and social development of North China area and resulted in deterioration of ecosystem and natural environment. Influenced by the climate change and human activities, the water circulation of NCP was largely changed and the crisis of water resources was aggravated. Therefore, it is important to study the features of the extreme climate and the response mechanism of groundwater to climate change. We analyzed the trend of climate change and extreme climate features in the past 60 years based on the monitoring data of meteorological stations. And then the response characteristics of groundwater to climate change were discussed. The average temperature of NCP was in an obviously upward trend. The overall precipitation variation was in a downward trend. The climate change in this area showed a warming-drying trend. The intensity of extreme precipitation displayed a trend of declining and then increasing from north to south as well as declining from eastern coastal plain to the piedmont plain. Grey correlation degree analysis indicated that groundwater depth had a close relationship with precipitation and human activities in NCP. The response of groundwater level to precipitation differed from the piedmont alluvial-pluvial plain to the coastal plain. The response was more obvious in the coastal plain than the piedmont alluvial-pluvial plain and the middle plain. The precipitation influenced the groundwater depth both directly and indirectly. Under the condition of extreme precipitation, the impact would aggravate, in the forms of rapid or lag raise of groundwater levels.

Impairment of the autophagy-lysosomal pathway in Alzheimer’s diseases: Pathogenic mechanisms and therapeutic potential

Alzheimer’s disease(AD),the most common neurodegenerative disorder,is characterized by memory loss and cognitive dysfunction.The accumulation of misfolded protein aggregates including amyloid beta(Aβ)peptides and microtubule associated protein tau(MAPT/tau)in neuronal cells are hallmarks of AD.So far,the exact underlying mechanisms for the aetiologies of AD have not been fully understood and the effective treatment for AD is limited.Autophagy is an evolutionarily conserved cellular catabolic process by which damaged cellular organelles and protein aggregates are degraded via lysosomes.Recently,there is accumulating evidence linking the impairment of the autophagy-lysosomal pathway with AD pathogenesis.Interestingly,the enhancement of autophagy to remove protein aggregates has been proposed as a promising therapeutic strategy for AD.Here,we first summarize the recent genetic,pathological and experimental studies regarding the impairment of the autophagy-lysosomal pathway in AD.We then describe the interplay between the autophagy-lysosomal pathway and two pathological proteins,Aβand MAPT/tau,in AD.Finally,we discuss potential therapeutic strategies and small molecules that target the autophagy-lysosomal pathway for AD treatment both in animal models and in clinical trials.Overall,this article highlights the pivotal functions of the autophagy-lysosomal pathway in AD pathogenesis and potential druggable targets in the autophagy-lysosomal pathway for AD treatment.

The distribution and sources of polycyclic aromatic hydrocarbons in shallow groundwater from an alluvial-diluvial fan of the Hutuo River in North China

This paper has investigated the concentration and distribution of polycyclic aromatic hydrocarbons in shallow groundwater from an alluvial-diluvial fan of the Hutuo River in North concentration levels of China.Results show that the 16 priority polycyclic aromatic hydrocarbons range from 0 to 92.06 ng/L,do not conform to drinking water quality standards in China (GB 5749-2006).However,the concentration figures of priority polycyclic aromatic hydrocarbons are much lower than that of other studies conducted elsewhere in China.In addition,highly-concentrated polycyclic aromatic hydrocarbons (50-92 ng/L)are fragmentarily distributed.The composition of polycyelic aromatic hydrocarbons from this study indicates that low molecular polycyclic aromatic hydrocarbons are predominant in groundwater samples, medium molecular compounds occur at low concentrations,and high molecular hydrocarbons are not detected. The polycyclic aromatic hydrocarbon composition in groundwater samples is basically the same as that of gaseous samples in the atmosphere in this study.Therefore, the atmospheric input is assumed to be an important source of polycyclic aromatic hydrocarbons,no less than wastewater discharge,adhesion on suspended solids,and surface water leakage.Ratios of specific polycyclic aromatic hydrocarbons demonstrate that they mainly originate from wood or coal combustion as well as natural gas and partially from petroleum according to the result of principal component analysis.On the whole,conclusions are drawn that the contamination sources of these polycyclic aromatic hydrocarbons are likely petrogenic and pyrolytic inputs.Future investigations by sampling topsoil,vadose soil,and the atmosphere can further verify aforementioned conclusions.