学簇合作学习课例探索

本文结合自己一个学期的新课程改革实践活动，在“学导螺旋发展大课堂”的大背景下，从学簇合作学习这一具体环节入手，探索如何构建和谐学簇，促进学生自主学习，从而使学生在新一轮课程改革中能够真正成为学习的主人，实现学习效率最优化。

透视学簇合作学习

自主、合作、探究是新课程提倡的学习方式，也是学生适应当今这个复杂多变社会的需要。因此，学生不仅要学会竞争，更应该学会如何与人合作，共同探究，实现共赢。

我们的课改向太阳

山西泽州一中自2009年5月起,义无反顾地推进课堂教学的革命性变革,重新定位课堂、改造课堂,再造教学流程,形成"学导螺旋发展大课堂"教学模式,即"137"模式。同时,通过学校管理改革的整体跟进以及争取内外部资源的强力支撑,为课堂教学改革保驾护航。

Math Imitation of the Texture of Particle Cluster Emitted from Diesel Engine

Aim The particle texture from diesel engine was imitated by use of computer. Methods The theory of fractal geometry and the diffusion limited aggregation model were used to simulate the micron texture. Results The fractal dimensions of granule distribution and corpuscle superficial area are quite conformed with those of measurement. Conclusion The texture parameters of engine particle cluster can be obtained precisely by use of fractal theory.

Adsorption Behavior of CH2 and CH3 on Metal Clusters CUn （n=1-6）

Using density functional theory with generalized gradient approximation and hybrid functional, we studied the properties of energy, charge population, and vibration of CH2 and CH3 adsorbed on Cun （n=1-6） clusters. The results show that the DFT calculation with the hybrid functional matches the experimental results better in both cases. The calculation results indicate that the adsorption of CH2 is stronger than that of CH3. During adsorption, the charges transfer from Cu to CH2 or CH3. The obtained vibrational frequencies for different modes of CH2 and CH3 adsorbed on Cun agree well with the experimental results for the adsorption on Cu（111） surface.

SEMI-EMPIRICAL CALCULATION FOR ELECTRONIC STRUCTURE OF C60 CLUSTER BY MOLECULAR DYNAMICS AND MNDO APPROACH

The electronic structure for C 60 was semi empirically investigated by using MD (molecular dynamics) and MNDO (modified neglect of diatomic overlap) approach of quantum chemistry.Especially,taking both σ and π orbitals into account,one electron energy levels,those symmetries and π orbital occupancies as well as electron excitation energies for different select rules,cohesive energy,ionization energies and electronic affinity forces were calculated.The obtained molecular orbital ratio shows a wide separation of σ and π types,and near HOMO and LUMO levels there are π orbitals mainly.The calculated semi empirical calculation results are in good agreement with experimental and ab initio calculation data.

Impact of Borate on Structure of Antifreeze Glycoproteins

Antifreeze glycoproteins(AFGPs)facilitate the survival of various organisms in the polar region by preventing internal ice accumulation via an adsorption-inhibition mechanism.Inhibition of AFGP antifreeze activity by the borate buffers has been widely acknowledged as the direct experimental evidence supporting the hydroxyl,rather than methyl,binding mechanism.On the other hand,perturbation of borate binding on the AFGP configuration,which might have considerable influence on the binding efficiency of not only the hydroxyl but also the methyl groups,has rarely been quantitatively examined.Herein we studied,using molecular dynamics simulations,the perturbation on the configuration of a solvated AFGP8 protein induced by the binding of one single borate anion.Near the freezing point,this binding not only makes the disaccharide groups adjacent to the borate-binding disaccharide close to each other but also affects the entire AFGP8 conformation.The structural changes induced by the binding of borate on different disaccharide sidechains exhibit clear site-specificities and the effect of borate binding on the structural changes is significantly reduced at higher temperatures.Our study is valuable for further understanding the relationship between the structure and antifreeze activity of these antifreeze glycoproteins.

Synthesis,Structure and Electrochemistry of Triruthenium Cluster Complex [Ru_3(μ_3- O)(μ-CH_3CO_2)_6(py)_2(PPh_2py)](PF_6)·CH_2Cl_2

The reaction between [Ru3(3-O)(-CH3CO2)6(py)2(MeOH)](PF6) (py = pyri- dine) and diphenyl-2-pyridyl-phosphine (PPh2py) gave the triruthenium cluster complex [RuIII3(3-O)(-CH3CO2)6(py)2(PPh2py)](PF6)CH2Cl2 (C40H44Cl2F6N34O13P2Ru3) which was characterized by elemental analysis, IR, UV-Vis and 31P NMR spectroscopy, and X-ray single- crystal diffraction. The structure is of monoclinic, space group P21/n with a = 16.3896(1), b = 16.8773(2), c = 19.1438(2) ? b = 95.888(1), V = 5267.47(9) ?, Mr = 1324.83, Dc = 1.671 g/cm3, F(000) = 2636, m = 1.092 mm-1 and Z = 4. The final refinement gave R = 0.0508 and wR = 0.1111 for 6987 observed reflections (I > 2s(I)). Three Ru(III) atoms bridged by m3-oxo donor form an approximately isosceles triangle. The complex shows three quasireversible one- electron processes at E1/2 = 1.22 +0.03 and 1.20 V vs. Ag/AgCl.

The Factorization of Adjoint Polynomials of E^G（i）-class Graphs and Chromatically Equivalence Analysis

Let Sn be the star with n vertices, and let G be any connected graph with p vertices. We denote by Eτp＋（r-1）^G（i） the graph obtained from Sr and rG by coinciding the i-th vertex of G with the vertex of degree r - 1 of S,, while the i-th vertex of each component of （r - 1）G be adjacented to r - 1 vertices of degree 1 of St, respectively. By applying the properties of adjoint polynomials, We prove that factorization theorem of adjoint polynomials of kinds of graphs Eτp＋（r-1）^G（i）∪（r - 1）K1 （1 ≤i≤p）. Furthermore, we obtain structure characteristics of chromatically equivalent graphs of their complements.

Baryon Magnetic Moment and Beta Decay Ratio in Colored Quark Cluster Model

Baryon magnetic moments of p, n, ∑^＋,∑^-,Ξ^0, Ξ^- and the beta decay ratios （G A/Gv ） of n → p, ∑^-→n and Ξ^0→∑^＋ are calculated in a colored quark cluster model. With SU（3） breaking, the model gives a good fit to the experimental values of those baryon magnetic moments and the beta decay ratios. Our results show that the orbital motion has a significant contribution to the spin and magnetic moments of those baryons and the strange component in nucleon is small.

Study on Infrared Spectra and Chemical Bonding of the Cluster Anion[Cl_2FeS_2MoS_2Cu(PPh_3)_2]￣-

The Fourier transform infrared spectra of the cluster anion[Cl2Fe2S2MoS2Cu(PPh3)2]- are measured between 550 and 90 cm(-1).The empirical assignments have been made for the vibration bands of main valence bonds.In order to verify the assignments of the bands and obtain the force constants the approximate normal coordinate analysis for the title anion has been carried out.It is found that the calculated frequencies are in good agreement with the observed ones.While Quantum-Chemical calculation is used to elucidate the chemical bonding characteristics for the title anion.

Diffusion Dynamics of Cux Cluster on Cu（111） Surface

The diffusion dynamics of small two-dimensional atomic clusters Cux （1≤x≤8） on Cu（lll） surface were studied using the molecular dynamics simulations and a modified analytic embedded-atom method in the temperature range from 200 K to 800 K. The cluster size and temperature dependence of the diffusion coefficients and migration energies are presented. Our simulations show that the diffusion migration energy of the CuT cluster is the highest and the prefactor for the CuT cluster is almost three orders of magnitude larger than that for single atom diffusion. This conclusion is consistent with the experimental results for similar metals. In addition, the dependence of cluster diffusion on film growth is also discussed.

Amorphous Fe Nanoclusters Embedded inside Balloon-Like N-Doped Hollow Carbon for Efficient Electrocatalytic Oxygen Reduction

Rational designs of electrocatalytic active sites and architectures are of great importance to develop cost-efficient non-noble metal electrocatalysts towards efficient oxygen reduction reaction(ORR)for high-performance energy conversion and storage devices.In this work,active amorphous Fe-based nanoclusters(Fe NC)are elaborately embedded at the inner surface of balloonlike N-doped hollow carbon(Fe NC/Csphere)as an efficient ORR electrocatalyst with an ultrathin wall of about 10 nm.When evaluated for electrochemical performance,Fe NC/Csphere exhibits decent ORR activity with a diffusionlimited current density of~5.0 mA/cm^(2)and a half-wave potential of~0.81 V in alkaline solution,which is comparable with commercial Pt/C and superior to Fe nanoparticles supported on carbon sheet(Fe NP/C sheet)counterpart.The electrochemical analyses combined with electronic structure characterizations reveal that robust Fe-N interactions in amorphous Fe nanoclusters are helpful for the adsorption of surface oxygen-relative species,and the strong support effect of N-doped hollow carbon is benefitial for accelerating the interfacial electron transfer,which jointly contributes to improve ORR kinetics for Fe NC/Csphere.

Analysis and Simulation of Molecular Dynamics of Lysozyme in Water Cluster System

The influence of water on protein conformation was investigated by simulating the molecular dynamics of a model protein lysozyme in different water systems.The lysozyme-water system with TIP3P water model and lysozyme-water cluster system with six-ring water model were evaluated.In addition,the radial distribution function of solvent around lysozyme was calculated.It is found that the distribution of water molecules around lysozyme is similar to that of water clusters.The analyses of dihedral angles and disulfide bonds of lysozyme show that the conformation of lysozyme is severely damaged in the lysozyme-water cluster system compared with that in the lysozyme-water system.This difference can be attributed to the formation of larger number of intermolecular hydrogen bonds between lysozyme and water cluster.It is in agreement with the analysis that water clusters can change the degree of denaturation in the process of heat denaturation of lysozyme.

Experimental and Theoretical Study of Hydrogen Atom Abstraction from Ethylene by Stoichiometric Zirconium Oxide Clusters

The reactions of cationic zirconium oxide clusters （ZrxOy^＋） with ethylene （C2H4） were investigated by using a time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source. Some hydrogen containing products （ZrO2）xH^＋（x=-1-4） were observed after the reaction. The density functional theory calculations indicate that apart from the common oxygen transfer reaction channel, the hydrogen abstraction channel can also occur in （ZrO2）x^＋＋C2H4, which supports that the observed （ZrO2）xH^＋ may be due to （ZrO2）x^＋＋C2H4→（ZrO2）xH^＋＋C2H3. The rate constants of different reaction channels were also calculated by Rice-Rarnsberger-Kassel-Marcus theory.

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物理法庭2——屁也是力量作者:[韩]郑玩相著出版:科学普及出版社定价:19.80元《有趣的科学法庭—物理法庭》系列图书从日常生活中经常接触到的一些棘手事件入手,试图运用物理学原理逐步解决。然而,判断这些大大小小事件的是非对错需要借助一个舞台,于是"物理法庭"便诞生了。本书借助法庭的形式,尽最大努力让大家的物理学习过程变得轻松愉快、越滋有味。读完本书后,大家一定会惊异于自己身上发生的变化。大家对物理的畏惧感已全然消失。

图书推荐

物理法庭1——拜拜了汽车作者:[韩]郑玩相著出版:科学普及出版社定价:19.80元《有趣的科学法庭—物理法庭》系列图书从日常生活中经常接触到的一些棘手事件入手,试图运用物理学原理逐步解决。然而,判断这些大大小小事件的是非对错需要借助一个舞台,于是"物理法庭"便诞生了。本书借助法庭的形式,尽最大努力让大家的物理学习过程变得轻松愉快、越滋有味。读完本书后,大家一定会惊异于自己身上发生的变化。大家对物理的畏惧感已全然消失,取而代之的是对科学问题的无限好奇。那就打开这本书。

Palladium-Carbon Composite Nanoparticle Films with Enhanced Electrocatalytic Activity for Hydrogen Peroxide Sensors

A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sensors. An enhancement on the electrocatalytic activity of the palladium nanoparticles toward H2O2 reduction was observed, which was related to the coverage of the carbon nanoparticles. With one monolayer of carbon nanoparticles, the H2O2 detection sensitivity reached the maximum, which was more than twice of that of the pure Pd nanoparticles.

Density functional investigation on structural and electronic properties of small bimetallic Pb_(n)Ag_(n)(n=2–12)clusters

Structural and electronic properties of PbnAgn(n=2–12)clusters were investigated by density functional theory with generalized gradient approximation at BLYP level in DMol3 program package.The optimized bimetallic PbnAgn(n=2–12)clusters were viewed as the initial structures,then,those were calculated by ab initio molecular dynamics(AIMD)to search possible global minimum energy structures of PbnAgn clusters,finally,the ground state structures of PbnAgn(n=2–12)clusters were achieved.According to the structural evolution of lowest energy structures,Ag atoms prefer gather in the central sites while Pb atoms prefer external positions in PbnAgn(n=2–12)clusters,which is in excellent agreement with experimental results from literature and the application in metallurgy.The average binding energies,HOMO-LUMO gaps,vertical ionization potentials,vertical electron affinities,chemical hardnessη,HOMO orbits,LUMO orbits and density of states of PbnAgn(n=2–12)clusters were calculated.The results indicate that the values of HOMO-LUMO gaps,vertical ionization potentials,vertical electron affinities and chemical hardnessηshow obvious odd-even oscillations when n≤5,PbnAgn(n=2–12)clusters become less chemically stable and show insulator-to-metal transition with the variation of cluster size n,PbnAgn(n≥9)cluster are good candidates to study the properties of PbAg alloys.Those can be well explained by the density of states(DOS)distributions of Pb atoms and Ag atoms between–0.5 Ha and 0.25 Ha in PbnAgn(n=2–12)clusters.