尽量让学生在玩中学 学中玩——谈谈“物体的相互作用”的探究性教学

以“物体的相互作用”为例，讨论了如何进行探究性教学．

物理情境虽异 解题方法类同——介绍两相互作用物体类问题的解法

要学好物理,有效提高解题能力.其中一条就是要掌握典型物理问题的求解方法.这样有利于学生举一反三,有效地提高解题的能力.在整个高中阶段物理教学中,这样的例子很多.现就两相互作用物体类问题的解法举例如下.

系统的动能定理

在高中阶段,动能定理一般只应用于单个物体,但动能定理也可应用于两个或两个以上的物体组成的系统,而且有时会使要解决的问题变得更为简单。但应用于系统时,应注意总功包括系统中所有物体相互作用的内力和系统外力做功的代数和,此时动能定理可表述为:系统中所有物体相互作用的内力和系统外力做的总功等于系统动能的增加,即:W外+W内=△Ek。

Effect of Cr(Ⅵ) and p-Chloroaniline Interaction on Their Reaction Behaviors on Soil Colloids

Adsorption of Cr(Ⅵ) and p-chloroaniline on three typical soil colloids and pH influence were studied using batch equilibrium method. Both of Cr(Ⅵ) and p-chloroaniline adsorption on the colloids could be well described by general adsorption simulation equations. The adsorption processes changed with media pH. When Cr(Ⅵ) and p-chloroaniline coexisted on soil colloids, their interactions could be observed in a certain pH range to be accompanied with Cr(Ⅵ) reduction, which clearly suggested that a surface catalytic reaction occurred in this system. Soil colloid acted as an efficient catalyst for the interaction of Cr(Ⅵ) and p-chloroaniline. The pH values at which no interaction was observed were 4.0, 4.5 and 5.0 for the colloids of indigotic black soil, yellow-brown soil and latosol, respectively. Capillary electrophoresis used to analyze p-chloroaniline provided a high separation efficiency and short separation time, and needed no more extensive pretreatment of samples.

Boosting chiral carboxylic acid hydrogenation by tuning metal-MO_(x)-support interaction in Pt-ReO_(x)/TiO_(2) catalysts

Engineering the surface microenvironment by tuning the binary interactions between a supported metal with a secondary metal oxide(MO_(x))or support has been a common method for improving the catalytic performance of supported metal catalysts.However,few studies have investigated the ternary interactions among the metal,MO_(x),and support.Here,we report for the first time the formation of metal-MO_(x)-support interaction(MMSI)in reducible TiO_(2)-supported PtReO_(x) catalysts,affording 87% yield and 100% ee in the tandem hydrogenation of an aqueous chiral cyclohexane-1,2-dicarboxylic acid into the corresponding diol;the catalytic activity is eight times higher than that obtained with non-reducible support counterparts in the same reaction via traditional batch synthesis with multiple steps and unfriendly reagents.Detailed experimental and computational studies suggest that the TiO_(2) crystalline phase-dependent density of the oxygen vacancies induces different Pt-ReO_(x)-TiO_(2) interactions,which dominate the electron transfer therein and tune the adsorption strength of the carbonyl moiety of the substrate/intermediate,thus promoting the hydrogenation activity and selectivity.In addition,the strong MMSI endows the optimal rutile TiO_(2) supported PtReO_(x) catalyst with an outstanding lifetime of 400 h in a fixed-bed reactor under acidic aqueous conditions and ensures efficient applications in the selective hydrogenation of aliphatic dicarboxylic acids and functional carboxylic acids.This work provides a promising strategy for the development of efficient and stable supported catalysts for the selective hydrogenation of diverse C-O and C=O bonds.

Promoting NO_(x)reduction via in situ activation of perovskite supported Pd catalysts under alternating lean-burn/fuel-rich operating atmospheres

Herein,we report the excellent De-NO_(x)performance of La0.7Sr0.3MnO3(LSM)perovskite-supported Pd catalysts(Pd-LSM)in alternating lean-burn/fuel-rich atmospheres using C3H6 as reductant and describe the in situ activation of the Pd catalysts via metal-support interaction(MSI)tuning.The NO_(x)reduction conversion of the Pd-LSM catalyst increased significantly from 56.1%to 90.1%and the production of N2O was suppressed.Our results demonstrated that this behavior was mainly attributed to the in situ transformation of Pd2+into Pd0 during the reaction.The generated Pd0 species could readily activate the C3H6 reductant and achieve an eight-fold higher turnover frequency than Pd2+for the reduction of NO_(x).Moreover,excessive MSIs inhibited the in situ generation of Pd0,and thereby,lowered the De-NO_(x)activity of the catalyst even at high Pd dispersion.In addition,the Pd-LSM catalysts exhibited much higher S tolerance than conventional Al_(2)O_(3)-supported catalysts.Our study provides a new approach for analyzing and designing highly active metal catalysts operated under dynamic alternating oxidizing/reducing atmospheric conditions.

Probing Molecular Interactions in 1-Butyl-3-methylimidazolium Chloride-Water and 2,6-Dimethoxyphenol Mixtures Using Attenuated Total Reflection Infrared Spectroscopy

Molecular interactions of the ternary mixtures of 1-butyl-3-methylimidazolium chloride （[C4C1im]Cl）-water-2,6-dimethoxyphenol （2,6-DMP, a phenolic monomer lignin model compound） were investigated in comparison with the [C4C1im]Cl-water binary systems through attenuated total reflection infrared spectroscopy. Results indicated that the microstructures of water and [C4C1im]Cl changed with varying mole fraction of [C4C1im]Cl （xIL） from 0.01 to 1.0. This change was mainly attributed to the interactions of [C4C1im]Cl-water and the self-aggregation of [C4C1im]Cl through hydrogen bonding. The band shifts of C-H on imidazolium ring and the functional groups in 2,6-DMP indicated that the occurrence of intermolecular interactions by different mechanisms （i.e., hydrogen bonding or π-π stacking） resulted in 2,6-DMP dissolution. In the case of xIL=0.12, the slightly hydrogen-bonded water was fully destroyed and [C4C1im]Cl existed in the form of hydrated ion pairs. Interestingly, the maximum 2,6-DMP solubility （238.5 g/100 g） was achieved in this case. The interactions and microstructures of [C4C1im]Cl-water mixtures influenced the dissolution behavior of 2,6-DMP.

The green fuel from carbon waste： optimization and product selectivity model studies

Increase in greenhouse gases, has made scientists to substitute alternative fuels for fossil fuels. Nowadays, converting biomass into liquid by Fischer-Tropsch synthesis is a major concern for alternative fuels （gasoline, diesel etc.）. Selectivity of Fischer-Tropsch hydrocarbon product （green fuel） is an important issue. In this study, the experimental data has been obtained from three factors; temperature, H2/CO ratio and pressure in the fixed bed micro reactor. T = 543-618 （K）, P = 3-10 （bar）, H2/CO = 1-2 and space velocity = 4500 （l/h） were the reactor conditions. The results of product modeling for methane （CH4）, ethane （C2H6）, ethylene （C2H4） and CO conversion with experimental data were compared. The effective parameters and the interaction between them were investigated in the model. H2/CO ratio and pressure and interaction between pressure and H2/CO in ethane selectivity model and CO conversion and interaction between temperature and H2/CO ratio in methane selectivity model and ethylene gave the best results. To determine the optimal conditions for light hydrocarbons, ANOVA and RSM were employed. Finally, products optimization was done and results were concluded.

π-π Stacking Force in the Solid Structure of Mixed-Metal Complexes: Zn(phen)_2MS_4 (M=W, Mo)

The inter-diffusion of N,N-dimethylformamide solution of Zn(phen)2Cl2 and (NH4)2MS4 (M = W, Mo) in an H-shape tube produced crystals of Zn(phen)2WS4 1 and Zn(phen)2MoS4 2 (phen = 1,10-phenanthroline). The structures of isomorphous complexes 1 and 2 have been determined by X-ray single-crystal structure analyses. Four nitrogen atoms from the phenanthroline ligands and two sulfur atoms from the MS42- anion forming a distorted octahedron coordinate each zinc atom. Through p-p interactions of adjacent aromatic rings of the phenanthroline ligands, a quasi one-dimensional zigzag-stacking column is formed in each complex. Complex 1 crystallizes in monoclinic space group C2/c, with a = 10.447(8), b = 22.016(9), c = 12.824(8) ? b = 103.56(6)? V = 2867.7(8) 3, Z = 4, C24H16N4S4WZn, Mr=737.90, Dc = 1.71 g/cm3, F(000) = 1424, m = 5.25 mm-1, the final R = 0.054 and Rw = 0.075 for 2315 observations with I > 3s (I). Complex 2 crystallizes in monoclinic space group C2/c, with a = 10.410(6), b = 22.095(7), c = 12.830(6) ? b = 103.19(8)? V = 2873.1(5) 3, Z = 4, C24H16MoN4S4Zn, Mr=649.99, Dc = 1.50 g/cm3, F(000) = 1296, m = 1.58 mm-1, the final R = 0.072 and Rw = 0.100 for 1631 observations with I > 3s(I).

Stimulated Emission of Gamma Photon from Ultrashort Pulse Intense Laser—Solid—Target Interaction

The efficient production of energetic γ photons is a significant physical process in the relativistic ultrashortpulse laser-plasma inducing photonuclear action. Based on the interaction of laser-solid-target, an analytical theory onstimulated γ photon emission from a hot electron firing the target-nucleus is developed by a relativistic full quantummethod. The emitting power or probability of γ photon in arbitrary space direction can be calculated for laser irradiatingsolid-target normally. It is valid only if the scatter-centre is immovable or its motion can be neglected compared withthat of the scattered electrons.

A New Energy Concept

According to the uncertainties in the results and the wide diversity of how to approach the subject, a new concept for energy is proposed： Energy is an exchange between two different concentrations, the concentration of time in space outside what we call matter and the concentrated phase of time in matter space which is the matter itself. The concept of motion for energy is replaced by time-space interactions with time taken as solid matter. Motion enhances the exchange between the mass and its surrounding time in space, annihilation and creation are special forms of this exchange. During the motion of a mass, it increases as a result of this dissolution. Time concentration in Fock space is responsible for the collision phenomena in physics. In this paper, a new mathematical operator （the equal operator） is introduced.

Influence of Intermolecular Hydrogen Bonding to Spin Crossover Property of Iron （111） Complexes with a N3O2 Pentadentate Ligand and a Monodentate Ligand

Three iron （III） complexes with the formula of [Feat（X）L2]BPh4 were studied, in which a pentadentate Schiff-base ligand （H2L2 = bis （3-methoxysalicylideneiminopropyl） methylamine） and a counter anion BPh4 were fixed, and three monodentate ligands, 3-Mepy （3-methylpyridine）, 4-NH2py （4-aminopyridine）, and 2-Meim （2-methylimidazole） were used as the axial ligand X. The temperature dependence of magnetic susceptibility measurements demonstrated that [Fem（3-Mepy）L2]BPh4 showed a gradual spin equilibrium between HS （high-spin） （S = 5/2） and LS （low-spin） （S = 1/2） states, [Fem（4-NH2py）L2]BPh4 showed a steep SCO （spin crossover） and [FeIH（2-Melm）L2]BPh4 was in the HS state even at 100 K. The single crystal X-ray analyses demonstrated that [FelH（4-NH2py）L2]BPh4 has an one-dimensional chain structure constructed by intermolecular hydrogen bonding between 4-amino group of 4-NH2py and methoxy oxygen of adjacent molecular-cation. The crystal structure of [FenI（3-Mepy）L2]BPh4 has no such intermolecular interaction and its SCO site behaves independently, and the crystal structure of [FeIII（2-Meim）L2]BPh4 has a NH...n interaction between imidazole group of 2-Meim of cation and a phenyl group of anion BPh4. The result demonstrates that the intermolecular hydrogen bonding affects SCO profile significantly.

Alteration in Biochemical Response in Sesamum indicum upon Different Plant-Pathogen Interactions

Sesamum, an important oil yielding crop suffers a huge loss in its yield due to attack of large number of fungal pathogens. In semi-arid regions Sesamum is mainly affected by two major plant-pathogenic fungus viz. Macrophomina phaseolina and Fusarium oxysporum. The aim of the study was to analyze the metabolic alterations in Sesamum after infection with both pathogens. This accomplished by individually by （the word estimating is not quantitative） the levels of total phenolic compounds and the activities of phenylalanine ammonia lyase （PAL） of one week old plants. The PAL showed high activity in infected plants, revealing the active phase in the synthesis of secondary metabolites in the Sesamum plant after infection. As a consequence, in infected plants the contents of polyphenols along with salicylic acid （SA） considerably exceeded when compared to control plants. This in vivo study of M. phaseolina and F. oxysporum infection reveals the differences of resistance levels in sesame against these two pathogens. These results provide important information regarding the plant-pathogen interactions and also forfor Sesamum improvement programs seeking the adaptation to diverse range of fungal attack along with adverse environmental factors.

Synthesis of amphiphilic poly(fluorene) derivatives for selective imaging of Staphylococcus aureus

Three amphiphilic poly（fluorene-co-phenylene） derivatives with different side chains （PFP-I, PFP-2, PFP- 3） were designed and synthesized for exploring their detection and imaging of pathogens. Upon incuba- tion with six kinds of different pathogens, it was found the three polymers could selectively interact with Staphylococcus oureus （S. aureus）. Their selective imaging towards S. aureus were thus realized. The selective imaging towards S. aureus was also confirmed even under the blend of microbes. PFP-3 shows stronger fluorescence imaging signal than PFP-1 and PFP-2. Zeta potential and isothermal titration microcalorimetry （ITC） tests demonstrated that both electrostatic interactions and hydrophobic interac- tions played important roles in the binding between PFPs and pathogens. Thus, amphiphilic PFP-3 exhi- bits great potential for specific imaging ors. aureus in a simple and rapid manner.