大一学生化学学习动机与实验室安全意识和态度的关系研究*

通过问卷调查方法研究大一学生化学学习动机和实验室安全意识与安全态度的关系。研究结果表明:不同学院学生的化学学习动机、实验室安全意识与安全态度等均有显著性差异;化工学院学生化学学习动机与实验室安全态度存在显著的中等程度正相关,其他学院则为弱相关。因此,教师应注意提高安全教育内容与专业的关联度,尽可能将课程内容与专业特色与专业应用相结合。     

Efficient and Sustainable in situ Photo-Fenton Reaction to Remove Phenolic Pollutants by NH2-MIL-101(Fe)/Ti3C2Tx Schottky-Heterojunctions

Metal-organic frameworks (MOFs) with abundant active sites, a class of materials composed of metal nodes and organic ligands, is widely used for photocatalytic degradation of pollutants. However, the rapid recombination of photoinduced carriers of MOFs limits its photocatalytic degradation performance. Herein, Ti₃C₂T_x nanosheets-based NH₂-MIL-101(Fe) hybrids with Schottky-heterojunctions were fabricated by in situ hydrothermal assembly for improved photocatalytic activity. The photodegradation efficiencies of the NH₂-MIL-101(Fe)/Ti₃C₂T_x (N-M/T) hybrids for phenol and chlorophenol were 96.36 % and 99.83 % within 60 minutes, respectively. The N-M/T Schottky-heterojunction duly transferred electrons to the Ti₃C₂T_x nanosheets surface via built-in electric fields, effectively suppressing the recombination of photogenerated carriers, thereby improving the photocatalytic performance of NH₂-MIL-101(Fe). Moreover, the Fe-mixed-valence in the N-M/T led to improvement in the efficiency of the in situ generated photo-Fenton reactions, further enhancing the photocatalytic activity with more generated reactive oxygen species (ROS). The study proposes a highly effective removal of phenolic pollutants in wastewater.     

A New Eremophilane Sesquiterpene from Cultures of the Fungus Pholiota nameko

Chemistry of Natural Compounds - A new eremophilane sesquiterpene (1), together with four known sesquiterpenes, donacinol B (2), donacinol C (3), trichapargin A (4), and trichapargin B (5), were...     

不同纵横比一水草酸钙晶体的合成、表征、吸附性能及其对肾上皮细胞的毒性差异

合成了长宽比分别为1∶2、1∶3、1∶4和1∶5的4种一水草酸钙(COM)晶体COM-1∶2、COM-1∶3、COM-1∶4和COM-1∶5,采用X射线衍射、傅里叶变换红外光谱、扫描电子显微镜(SEM)、ζ电位仪和比表面测试仪等对其理化性质进行了表征。SEM图片显示晶体的宽度相近,但长度分别为(3±0.3)μm、(5.2±0.3)μm、(7.0±0.7)μm和(8.8±1.2)μm。随着反应温度升高,生成的晶体长度变长;搅拌速度越大,生成的晶体尺寸越小;随着添加剂明胶的浓度减小,COM晶体的(101)面被拉长。细胞活力、细胞总死亡率和活性氧检测表明,不同长宽比COM对人肾近端上皮细胞(HK-2)的毒性大小为COM-1∶2>COM-1∶3>COM-1∶4>COM-1∶5>对照组,SEM检测证明4种COM晶体均能够黏附到细胞表面。毒性差异与以下各原因呈正相关：晶体大比例的(101)晶面、大的比表面积、大的细胞-晶体剪切应力。     

Products and mechanism for the OH radical initiated oxidation of acrylonitrile,methacrylonitrile, and allylcyanide in the presence of NO

The photooxidation of acrylonitrile, methacylonitrile, and allylcyanide in the presence of NO was studied in parts per million concentration using the long-path Fourier transform IR spectroscopic method. The stoichiometry of the OH radical initiated oxidation of methacrylonitrile was established as \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm C}\left( {{\rm CH}_{\rm 3} } \right){\rm CN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{1.0} {\rm HCHO + CH}_{\rm 3} {\rm COCN + 2NO}_{{\rm 2}} + \left( {{\rm OH}} \right) $\end{document}. The yield of HCHO for acrylonitrile and allylcyanide was found to be ca. 100 and 80%, and the stoichiometric reactions were assessed to proceed, \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm CHCN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{1.0} {\rm HCHO + HCOCN + 2NO}_{\rm 2} + \left( {{\rm OH}} \right) $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \left( {{\rm OH}} \right) + {\rm CH}_{\rm 2} = {\rm CHCH}_{\rm 2} {\rm CN + 2NO + 2O}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^{0.8} {\rm HCHO + HCOCH}{\rm 2} {\rm CN + 2NO}_{\rm 2} + \left( {{\rm OH}} \right) $\end{document}, respectively. These results revealed that the reaction mechanism for these unsaturated organic cyanides are analogous to that of olefins.     

Ionization of 1-D model atom in an intense laser field based on asymptotic boundary conditions and symplectic algorithm

In this paper the asymptotic boundary condition (ABC) of 1-D model atom in the intense laser field at the spatial sufficiently far distance is presented using Fourier transformation on the condition that the initial state is local and the atomic potential in the model falls off rapidly. On the basis of this ABC, the symplectic algorithm is developed for computing the model atom in the intense laser field. The ABC and symplectic algorithm are applied to compute the ionization behaviors for 1-D Pöschl–Teller short-range potential. The numerical results illustrate that the ABC and the symplectic algorithm presented are reasonable and effective for 1-D model atom in the intense laser field.     

Studies on the Refolding of Egg White Lysozyme Denatured by Urea Using ＂Phase Diagram＂ Method of Fluorescence

The refolding of reduced and non-reducing egg white lysozymes in a urea solution was studied by a ＂phase diagram＂ method of fluorescence. The result showed that in the refolding of the reduced egg white lysozyme, an intermediate state of an egg white lysozyme exists at the urea concentrations in a final renaturation solution being about 4.5 mol/L, their refolding follows a three-state model; while in the refolding of the non-reducing egg white lysozyme, two intermediate states exist at the urea concentrations being separately 4.0 and 2.5 mol/L, and their refolding follows a four-state model. Through the comparison between the unfolding and refolding of an egg white lysozyme in the urea solution, it was found that both of the refolding of reduced and non-reducing egg white lysozyme molecules was irreversible to their unfolding in the urea solution. Finally, a suggested refolding was separately presented for the reduced and non-reducing egg white lysozymes in the urea solution.     

Effect of the semirigid capping ligand on the structure formation of cyano-bridged bimetallic assemblies: syntheses, crystal structures, and magnetic properties

The syntheses, crystal structures, and magnetic properties of three novel cyano-bridged bimetallic assemblies, [Ni(bpm)(2)](3)[Co(CN)(6)](2)x3.5H(2)O (1), [Co(bpm)(2)][Fe(CN)(5)NO]x2H(2)O (2), and [Co(bpm)(2)][Ni(CN)(4)] (3) (bpm = bis(1-pyrazolyl)methane), are reported. Complex 1 crystallizes in the tetragonal space group P4(3)2(1)2 with a = 12.800(5) A, b = 12.800(5) A, c = 42.80(3) A, V = 7012(6) A(3), and Z = 8. Complex 2 crystallizes in the chiral trigonal space group P3(2)21 with a = 11.9961(19) A, b = 11.9961(19) A, c = 16.062(5) A, gamma = 120 degrees , V = 2001.7(8) A(3), and Z = 3. Complex 1 is a trigonal bipyramidal complex in which three [Ni(bpm)(2)](2+) units are situated in the equatorial plane and are connected to the two apical [Co(CN)(6)](3)(-) units via three N ends of the cyanide groups. Complex 2 possesses a triangular left-handed helical chain structure composed of [Co(bpm)(2)](2+) linked by [Fe(CN)(5)NO](2)(-); the shortest intramolecular Co...Fe distance is 5.162 A. To the best of our knowledge, this is the first observation of a heteronuclear helical chain structure based on pentacyanonitrosylferrate(II). The structure of complex 3 is roughly determined by X-ray crystallograhy analysis to be a 1D zigzag chain. These structure variations, from a discrete cluster to a 1D helical chain and a 1D zigzag chain, rely on the semirigidity of the capping ligand bpm. Magnetic susceptibility measurements indicate that complex 1 has an intramolecular ferromagnetic interaction (J = 4.06 cm(-)(1)) between the nickel(II) ions; this is further confirmed by the magnetization measurements. In complexes 2 and 3, the cobalt(II) ions are located in a moderately strong field.     

A novel coordination polymer with dicyanamide ligand: multi-dimensional architecture stabilized by hydrogen bonding

A novel dicyanamide (dca) complex, [Cu(pn)(dca)₂]_n (pn=1,2-diaminopropane), was synthesized and characterized. X-ray diffraction analysis reveals that the title complex crystallizes in the monoclinic space group C2/c with β=96.662(6)°, Z=8, and R₁=0.0476, wR₂=0.1094. The complex exhibits one-dimensional zigzag chain structure constructed by μ_1,5-dca bridges. The coordination geometry around the copper atom was a distorted square-pyramid. The spectroscopic and magnetic properties have also been discussed.     

Numerical simulation and experimental verification of particle coagulation dynamics for a pulsed input

Mathematical simulation of particle coagulation dynamics was carried out using improved sectional modeling techniques for a system with a pulsed input of primary particles. The methodological improvement included the modification of the size density function based on a realistic assumption of particle size distributions, the application of a new and comprehensive curvilinear collision model, and special adjustment for the mass transfer of a doublet of particles that were very different in size. The simulation results demonstrated that the rectilinear model over-predicted the rate of particle coagulation and that the degree of over-prediction increased as the particles increased in size and the system became more heterogeneous. The coagulation rate increased remarkably as the fractal dimension of the particle aggregates decreased. The curvilinear model and the fractal scaling relationship in place of the rectilinear model and the Euclidean sizing geometry are two important modifications to the conventional Smoluchowski modeling approach. However, both modifications, rather than only one of them, should be applied together to produce more accurate and realistic simulations of coagulation dynamics. As indicated by the simulation, the importance of fluid shear rate to particle coagulation is reduced according to the curvilinear model compared to that previously described with the rectilinear model. As particles increased in size, the role of shear rate in coagulation became even less significant according to the curvilinear view of particle collisions. The results of numerical simulations in terms of the evolution of particle size distributions compared reasonably well with the observations of the jar-test coagulation experiments, which suggested the applicability of the modeling system, including the modified curvilinear-fractal approach, established in the present study.