人工智能助力当代化学研究

以机器学习为代表的人工智能在当代的科学研究中正在发挥越来越重要的作用.不同于传统的计算机程序,机器学习人工智能可以通过对大量数据的反复分析和自身模型的优化,即“学习”过程,从而在大量的数据中寻找客观事物的相互联系,形成具有更好预测和决策能力的新模型,做出合理的判断.化学研究的特点恰恰是机器学习人工智能的强项.化学研究经常要面对十分复杂的物质体系和实验过程,从而很难通过化学物理原理进行精准的分析和判断.人工智能可以挖掘化学实验中产生的海量实验数据的相关性,帮助化学家做出合理分析预测,大大加速化学研发过程.本文介绍了当代人工智能方法及用其解决化学问题基本原理,并通过具体案例展示了人工智能辅助解决不同化学研发问题的方法以及对应的机器学习算法.将人工智能运用在化学科学的尝试正处于蓬勃上升期,人工智能已经初步展示出对化学研究的强大助力,希望本文能帮助更多的国内的化学工作者了解和运用这一有力的工具.     

牛奶中碳、氮、氢和氧稳定同位素比的测定及其在产地溯源分析中的应用

应用元素分析-同位素质谱仪(EA-IRMS)和多用途气体制备-连续流稳定同位素质谱仪(GasBench-IRMS)分别测定了来自国内外7个不同国家(澳大利亚、新西兰、西班牙、德国、奥地利、意大利和中国)的83件牛奶样品中碳、氮、氢、氧的稳定同位素比值(δ13 C、δ15 N、δ2 H和δ18 O)。对所测得的数据用SPSS 20.0软件分别进行了方差分析、聚类分析以及牛奶产地的判别分析。从所得结果可见,上述4项稳定同位素比值中的每一项都可获得相关牛奶样品产地来源的若干信息,但还不足以作为相关牛奶样品的溯源地判别的充分依据。而将测试结果进行组合后,对δ13 C、δ15 N和δ2 H三项指标组合交叉检验整体判别正确率达到84.3%,据此采用3项组合指标对牛奶产地进行判别分析,并在此项组合指标的基础上建立了产自7个国家的牛奶的判别模型。对自来这7个不同国家的牛奶盲样进行判别时,可将所测得样品中上述3项稳定同位素的δ值代入所建立的模型中,并比较各模型所得的Y值的大小,其中Y值最大的,即归属于此模型所代表的国家。     

物理化学学科前沿与发展——“化学的创新与发展论坛”苏州大学分论坛纪要

2013年12月19日,"化学的创新与发展论坛"苏州大学分论坛在苏州大学成功举办.本次论坛由《中国科学》杂志社与苏州大学材料与化学化工学部联合主办,主要目的是促进物理化学的学科发展与人才培养,并对《中国科学:化学》期刊进行宣传.     

含酰亚胺骨架的大环化合物合成、结构及其对阴离子的识别研究

在磷酸催化作用下,采用前体二胺N,N’-(2-胺基苯基)-2,6-二甲酰亚胺吡啶(1)和前体二醛1,4-二(2’-甲酰苯氧基)丁烷(2)进行缩合作用得到[1+1]Schiff碱大环化合物3,进一步将Schiff碱大环3还原得到饱和大环4.并采用1H NMR,IR,质谱和元素分析等技术对大环3和4的组成进行了表征.采用X射线单晶衍射技术测定了Schiff碱大环3的晶体结构,结果表明大环3具有扭曲的"8"字形结构.采用UV-vis光谱滴定技术对大环与系列阴离子的键合作用进行了考察,结果表明,Schiff碱大环3对F-离子有明显的选择性识别作用,并测定了该配位反应的配位比和平衡常数.     

Iron-mediated AGET ATRP of styrene and methyl methacrylate using ascorbic acid sodium salt as reducing agent

Atom transfer radical polymerization of styrene(St) and methyl methacrylate(MMA) in bulk and in different solvents using activators generated by electron transfer(AGET ATRP) were investigated in the presence of a limited amount of air using FeCl3·6H2O as the catalyst, ascorbic acid sodium salt(AsAc-Na) as the reducing agent, and a cheap and commercially available tetrabutylammonium bromide(TBABr) as the ligand. It was found that polymerization in THF resulted in shorter induction period than that in bulk and in toluene for AGET ATRP of St, while referring to AGET ATRP of MMA, polymerization in THF showed three advantages compared with that in bulk and toluene: 1) shortening the induction period, 2) enhancing the polymerization rate and 3) having better controllability. The living features of the obtained polymers were verified by chain end analysis and chain-extension experiments.     

电沉积－退火工艺制备铜铟硒太阳能电池薄膜及表征

利用电沉积硒气氛下后续退火的工艺制备出了高结晶质量的铜铟硒薄膜．通过X射线衍射、扫描电子显微镜、拉曼光谱、紫外-可见-近红外光谱和阻抗谱技术对退火后的铜铟硒薄膜进行表征,结果表明530 oC硒化退火后的铜铟硒薄膜具有四方的黄铜矿晶体结构,晶粒尺寸达到微米量级,光学带隙为0.98 eV,经过KCN溶液去除表面高导电性的铜硒化合物后铜铟硒薄膜的载流子浓度在10¹⁶ cm^-3量级．利用硒化退火的铜铟硒薄膜作为光吸收层制备了结构为AZO/i-ZnO/CdS/CIS/Mo/glass的太阳能电池,在AM1.5光照条件下对其电流-电压特性测试后发现面积为0.2 cm²的电池可以达到0.96％的能量转换效率,并对限制电池效率的原因做出了初步的分析和讨论.     

刚性衬底上铜铟硒纳米棒阵列的合成与表征

在覆盖有钨电极的硅衬底上利用多孔阳极氧化铝模板为生长掩膜电沉积合成垂直排列的铜铟硒纳米棒阵列. 多孔阳极氧化铝模板由阳极氧化磁控溅射制备的铝膜制成. 扫描电子显微镜结果表明,该纳米棒阵列结构致密,直径约100 nm长度约1μm,纵横比为10. X射线衍射、微区拉曼光谱和高分辨透射电子显微镜结果表明,真空条件下450 oC退火处理的铜铟硒纳米棒是多晶纯相的黄铜矿结构的铜铟硒,在纳米棒轴向方向上有比较大的晶粒尺寸. 能量色散X射线光谱表明,铜铟硒纳米棒的化学组成接近InSe₂的化学计量比,由吸收光谱分析推算铜铟硒纳米棒带隙为0.96 eV.     

计算机辅助装调与传统基准传递技术相结合实现三镜消像散系统的装调

为满足复杂航天光学系统对精度的要求,克服传统基准传递技术与计算机辅助装调技术对多于3片反射镜的复杂光学系统进行装调时存在的局限性,提出了两种技术相结合的装调方法。采用提出的方法对三镜消像散(TMA)空间相机进行了装调,结果显示:三镜在Y向和Z向的失调量分别由18.651和9.879 mm降低到1.036和0.102 mm,系统波前差达到全视场平均值1/14λ(RMS)。结果证明:此方法能有效缩短装调时间并达到系统要求的精度指标,对于多镜复杂光学系统装调具有指导和参考价值。     

The structure and the potential energy function of AlSO(C_S,X~2A″)

By using the B3P86/aug-cc-pvtz method,the accurate equilibrium geometry of the AlSO(CS,X2A″) molecule has been calculated and compared with available theoretical values.The obtained results show that the AlSO molecule has a most stable structure with bond lengths of R OAl = 0.1864 nm,R OS = 0.1623 nm,R AlS = 0.2450 nm,together with a dissociation energy of 13.88 eV.The possible electronic states and their reasonable dissociation limits for the ground state of the AlSO molecule were determined based on the principle of atomic and molecular reaction statics.The analytic potential energy function of the AlSO molecule was derived by the many-body expansion theory and the contour lines were constructed for the first time,which show the internal information of the AlSO molecule,including the equilibrium structure and stable point.The analysis demonstrates that the obtained potential energy function of AlSO is reasonable and successful and the present investigations provide important insights for further study on molecular reaction dynamics.     

The role of vacancy,impurity,impurity-vacancy complex in the kinetics of LiNH2 complex hydrides:a first-principles study

This paper studies first-principles plane-wave pseudopotential based on density functional theory of hydrogen vacancy,metal impurity,impurity-vacancy complex in LiNH 2,a promising material for hydrogen storage.It finds easy formation of H vacancy in the form of impurity-vacancy complex,and the rate-limiting step to the H diffusion.Based on the analysis of the density of states,it finds that the improvement of the dehydrogenating kinetics of LiNH 2 by Ti catalysts and Mg substitution is due to the weak bonding of N-H and the new system metal-like,which makes H atom diffuse easily.The mulliken overlap population analysis shows that H vacancy leads to the H local diffusion,whereas impurity-vacancy complexes result from H nonlocal diffusion,which plays a dominant role in the process of dehydrogenation reaction of LiNH 2.