太湖梅梁湾水下光场扰动的特征分析

在水体表面波的扰动作用下,水下光场随深度呈现较为明显的波动现象,且水中光合作用会对水下光场波动作出响应,因而此现象引起了广泛的关注。基于太湖梅梁湾观测的水下光场数据,计算了水下光场随深度的变化,并分析了其波动特征。结果表明:表面波引起了水下光场较为明显的波动现象,波动振幅最大的深度基本小于20 cm,远小于海洋中对应的深度;水下光场波动的振幅随深度呈e的负指数衰减,漫射消光系数越大,水下光场的波动衰减得也越快;当深度大于30 cm时,水下光场的扰动现象基本消失。还计算了船舶对水下光场观测的影响,发现直射光未被遮挡的情况下,漫射比例越高,其相对误差越大。     

On the weighting method for mixed least squares–total least squares problems

It is well known that the standard algorithm for the mixed least squares–total least squares (MTLS) problem uses the QR factorization to reduce the original problem into a standard total least squares problem with smaller size, which can be solved based on the singular value decomposition (SVD). In this paper, the MTLS problem is proven to be closely related to a weighted total least squares problem with its error‐free columns multiplied by a large weighting factor. A criterion for choosing the weighting factor is given; and for the sake of stability in solving the MTLS problem, the Cholesky factorization‐based inverse (Cho‐INV) iteration and Rayleigh quotient iteration are also considered. For large‐scale MTLS problems, numerical tests show that Cho‐INV is superior to the standard QR‐SVD method, especially for the case with big gap between the desired and undesired singular values and the case when the coefficient matrix has much more error‐contaminated columns. Rayleigh quotient iteration behaves more efficient than QR‐SVD for most cases and fails occasionally, and in some cases, it converges much faster than Cho‐INV but still less efficient due to its higher computation cost.     

Roundoff Error Estimates of the Modified Gram–Schmidt Algorithm with Column Pivoting

In this paper we provide backward and forward roundoff error estimates of the modified Gram–Schmidt algorithm with column pivoting. It turns out that the row-wise growth factors of this algorithm are bounded. Furthermore, if the coefficient matrix is well conditioned, then with properly chosen tolerance , this algorithm can also correctly determine the numerical rank of the coefficient matrix. We also derive a forward roundoff error estimate of this algorithm for the solution of the least squares problem.     

Study on synthesis and electrochemical properties of a novel ferrocene-based compound and its application in anion recognition

The novel ferrocene-based compound 2-Fc is synthesized through the reaction of ferrocene carbonate acid and epoxy rosin E-51, and characterized by 1H NMR. The CV behaviors of 2-Fc in different organic solvents are recorded, and the major influential factors, namely, potential scan rate, concentration of electrolyte, and concentration of 2-Fc, and the mechanism of the electrode process are investigated. The CV behaviors of 2-Fc film on electrode in LiClO4 aqueous and organic solutions and the application of 2-Fc in H2PO4- recognition are also studied.     

通过拓展大学化学实验培养学生探索创新能力——以“硫酸铜中铜含量测定(碘量法)”为例

在大学化学实验"硫酸铜中铜含量测定(碘量法)"过程中,探索加入KSCN时机及不加入KSCN对滴定测试结果的影响,并且采用不同浓度的硫酸铜溶液进行验证。实验结果显示,碘量法测定铜含量过程中,临近滴定终点加入KSCN、滴定到浅黄色时加入淀粉之后加入KSCN,两者测试结果基本一致;但在加入KI之后加入KSCN、不加入KSCN,铜含量测定结果明显偏低。该研究可应用于本科实验教学,按不同实验条件将学生分组,在分别实验基础上,引导学生对各组实验结果进行对比、分析及讨论,从而培养学生探索创新意识,有效改进"唯书本"的教学方法。     

第11届全国大学生化学实验邀请赛有机化学实验试题解析

介绍了第11届全国大学生化学实验邀请赛有机化学实验操作试题的命题思路,并对实验中存在的问题及成绩进行了分析。     

N‐Triazolylpropanamide – an Acrylamide‐Derived Multifunctional Ligand for the Construction of Supramolecular Hydrogen‐Bonded Networks

The synthesis and single crystal X‐ray structure of the multifunctional acrylamide‐derived ligand N‐triazolylpropanamide ( 1 , = NTPA) are reported. The title compound was prepared in 72 % yield by Michael addition of 1, 2, 4‐triazole and acrylamide in the presence of Triton B (= trimethylbenzylammonium hydroxide) as catalyst. Treatment of 1 with FeCl₃(H₂O)₆ in MeOH/MeCN led to reduction and formation of the iron(II) complex (NTPA)₂FeCl₂(MeOH)₂ ( 2 , yellow prisms, 52 % yield). Both 1 and 2 were structurally characterized by X‐ray diffraction. Surprisingly, the NTPA ligands in 2 are coordinated to iron in a monodentate fashion through a triazole ring nitrogen atom. In the crystal, both compounds form supramolecular hydrogen‐bonded networks.     

浅水湖泊中介质吸收系数的反演

基于在太湖、天目湖观测的水下光场资料,假定在水体中无内光源及无非弹性散射的情况下,通过水体中向上、向下的辐照度廓线分布,及由此确定的漫射反射率、漫射衰减系数,较为成功地反演了水体中介质的固有光学参数--吸收系数,且在较大程度上降低了由波浪及船舶阴影所带来的误差.同时将该反演结果与通过定量滤膜技术测定的结果进行了比较,二者吻合得较好.该方法有利于研究进入水体的太阳辐射能在各介质之间的分配及水生生态系统对水下光场的响应、大型浅水湖泊中蓝藻水华的暴发机理、提高二类水体水质定量遥感精度.     

第11届全国大学生化学实验邀请赛无机及分析化学实验试题评析与思考

介绍了第11届全国大学生化学实验邀请赛无机及分析化学实验操作试题的命题思路,并对实验中存在的问题及成绩进行了总结分析。