科研问题向课堂教学的融入

科研向教学的融入常常注重科研成果在教学上的分享,而科研问题在教学中的重要作用却往往被忽视。为提高教学效果,本文尝试在课堂教学中选取科研成果取得过程中遇到的某个问题为切入点,抛转引玉,由学生运用所学知识,通过查阅资料和课堂讨论,思考解决办法。     

Palladium-catalyzed tandem cyclization/Suzuki coupling of 1,6-enynes: reaction scope and mechanism

A palldium(0)-catalyzed tandem cyclization/Suzuki coupling reaction of various 1,6-enyne substrates was developed. This Pd-catalyzed enyne cyclization reaction represents a new process for the synthesis of stereodefined alpha-arylmethylene-gamma-butyrolactones, lactams, multifunctional tetrahydrofurans, pyrrolidines, and cyclopentanes. The mechanism of the reaction was studied by the employment of different enyne isomers and boronic acids; a pi-allyl palladium intermediate was suggested to explain the formation of the cyclic products. The stereochemistry of this reaction can be well explained by a chairlike transition state.     

纳升电喷雾毛细管液相色谱-串联质谱鉴定K562细胞株中混合蛋白质

用标准蛋白质混合物建立了一种适用于低丰度混合蛋白质及其异构体分离与鉴定的蛋白质组学方法。通过IPG胶条等电聚焦分离蛋白质,染色后进行混合胶内酶切,采用纳升电喷雾毛细管液相色谱一串联质谱“散弹法（shot-gun）”分析酶切产物,并进行数据库检索鉴定蛋白质。运用该方法从K562细胞株样品中鉴定出14种具有重要功能的蛋白质,部分蛋白质同时在多个条带中出现,可能是异构体。肽段及其碎片离子的平均质量偏差小于0．05U,综合得分大都远远超过有效值。该方法灵敏、准确度高、分辨率高、省时、便于操椎存苍宗罾白甩异构体青而右优势．     

Chemical composition of “AKD vapour” and its implication to AKD vapour sizing

Alkyl ketene dimer (AKD) sizing of paper involves the redistribution of the wax over the fibre surface upon heating. The two major mechanisms widely studied so far are the spreading of an autophobic precursor of molten AKD and AKD vapour transport and re-deposition on the fibre surface. All previous work assumed that the transport of AKD vapour could be expressed by the change of water contact angle with substrates that were exposed to the vapour. Information regarding the chemical composition of the vapour phase above the AKD wax has not been found in the literature. In this work, a simple method for analysing the chemical composition of the vapour is established. Our preliminary results indicated that the chemical composition of AKD vapour in the temperature range of 75–80 °C is dominantly fatty acids. This suggests that the sizing effect by actual AKD molecules via the vapour deposition mechanism is likely to be insignificant in this temperature range. This also implies that fatty acids play a positive role in AKD sizing. The chemical stability of AKD in this temperature range is also studied.     

Making High Selective Molecule Imprinting Polymer (MIP) In Polar Solvent

IntroductionMoleculeimprintingtechnologyhasmadegreatprogressinmakingchiralstationaryphasewithpredeterminedchiralselectivityagainstenantiomerssuchasaminoacidandtheirderivatives;sugarandtheirderivatives;naproxenandmethylbenZylamine'-'.Functionalmonomer...     

Bis-radicals (nitronyl nitroxide and imino nitroxide) Substituted Benzene with Long Alkyl Chain: Synthesis, Magnetic Study and Formation of LB film

Sincethediscovery0fthefirstgenuineorganicferr0magnet,p-nitronylphenylnitronylnitroxide(P-NPN-N)in1991',greatprogresshasbeenachievedinthefieldof0rganicferromagnetism.Bynow,morethantwentypurelyorganicferromagnetshavebeenrep0rtedsuccessiveIy'.However,theferr0magnetictransiti0ntemperature(Tc)0fthesepurely0rganicferr0magnetsarestillveryl0wwiththehighestbeing0nlyl.48K3exceptforthecharge-transfercomplexesbasedontetracyanoquinodimethane(TCNQ)andC604.Atpresentstageofresearchinthisfield,0n0nehand,e…     

新冠病毒刺突蛋白及其受体的结构与相互作用

Biochemistry is a branch subject of chemistry, which is the study of chemical structures and processes associated with living organisms. COVID-19 pandemic is a problem for human beings. From the perspective of biochemistry, this paper demonstrates the chemical structure and interactions of SARS-CoV-2's spike protein and its receptor (human angiotensin converting enzyme 2), and summarizes the related research progresses. The authors hope to provide insights for the development of COVID-19 vaccine.     

高分散还原态Pt基催化剂的制备及其NO氧化的催化性能

Pt⁰被认为是NO氧化的活性物种,而催化剂的制备方法对活性物种的含量起着决定性作用。本文采用非惰性气氛保护的改性醇还原-浸渍法(MARI)合成了高分散高Pt⁰含量的1% (w, 质量分数) Pt/SiO₂-Al₂O₃催化剂(MA-Pt/SA)。X射线粉末衍射(XRD)、CO-漫反射傅里叶变换红外吸收光谱(CO-DRIFTS)和透射电镜(TEM)表征证实在550 ℃焙烧3 h后催化剂的Pt颗粒仅有3.8 nm。同时,X射线光电子能谱(XPS)和H₂-程序升温还原(H₂-TPR)结果表明催化剂具有高Pt⁰含量(60.3%)。模拟柴油车尾气气氛进行活性测试,并与传统浸渍法制备的1% (w) Pt/SiO₂-Al₂O₃催化剂(C-Pt/SA)对比,结果显示MA-Pt/SA具有优异的催化氧化性能,其NO最大转化率高达74%,比C-Pt/SA的NO转化率高了23%。经670 ℃高温老化15 h后,老化的MA-Pt/SA的NO转化率仍然高达69%。此外NO + O₂共吸附原位漫反射傅里叶变换红外吸收光谱(in situ DRIFTS of NO + O₂ co-adsorption)表明高的Pt分散度和高Pt⁰含量能够促进中间物种桥式硝酸盐的生成及分解,进而导致了优异的NO氧化活性。最后,利用同样方法将Pt的负载量降低至0.5% (w)制备催化剂,NO转化率仍达64%。这种制备方法能够获得低贵金属高性能的Pt基催化剂。     

低共熔溶剂分散液液微萃取-悬浮固化-高效液相色谱法测定水产品中3种内分泌干扰物的含量北大核心CSCD

将癸酸和香叶醇在10 mL玻璃管中以2∶1的物质的量之比混合,然后将混合物在80℃水浴锅中加热,直至形成稳定的低共熔溶剂(DES)。该溶剂易合成、低成本、低毒性且具有高生物降解性,是一种新型的疏水性DES,可用于水产品中内分泌干扰物的微萃取。取已粉碎的水产品样品1 g和乙腈2 mL置于5 mL离心管中,以转速2 000 r·min^(-1)涡旋振荡3 min。取上清液400μL,经0.45μm滤膜过滤,滤液与100μL DES混合,并迅速注入装有5 mL 80 g·L^(-1)氯化钠溶液的10 mL离心管中,以完成DES的分散。将上述离心管以转速3 500 r·min^(-1)离心5 min,然后置于冰浴中进行固化。将固化后所得样品溶解于150μL甲醇中,以Eclipse Plus C;色谱柱为分离柱,以体积比90∶10的甲醇-水的混合液为流动相,在激发波长228 nm,发射波长305 nm处测定双酚A、4-叔辛基苯酚和壬基酚等3种内分泌干扰物的含量。结果表明,DES在冰浴中固化,可促进其从水溶液中分离,简单且快速,利于萃取剂的收集。3种内分泌干扰物的质量分数均在0.25~10μg·g^(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)均为0.075μg·g^(-1)。用此法对空白加标样品进行测定,测定值的日内和日间相对标准偏差(n=5)均小于4.0%。以空白样品为基体进行加标回收试验,所得回收率为78.7%~91.6%。     

基于元素指纹的白术产地溯源及其与土壤的相关性研究

本研究主要采用电感耦合等离子体质谱仪(ICP-MS)等手段测定5个产地白术41种矿质元素含量和土壤41种化学成分指标, 结合聚类分析法、偏最小二乘判别分析(PLS-DA)法和Pearson相关性分析研究了不同产区白术矿质元素特征以及不同产区土壤因子的差异, 并对它们的相关性进行了探讨. 结果表明, 采用无监督的聚类分析和有监督的PLS-DA均能正确判别不同产地的白术和土壤, 其中稀土元素在浙江白术与土壤间呈正相关. 另外, Li、V、Mn、Co、Cu、Rb、Cd、Cs、Ba等微量元素是白术产地溯源的关键因素. 研究发现在白术生产实践中可以通过适量控制种植地的土壤湿度、增施特定肥料等措施调控白术矿质元素含量. 本研究将为解释道地白术的品质形成机制, 保证白术药效质量的有效性提供一定帮助.