运用现代教育技术优化物理实验教学

所谓现代教育技术，就是运用现代教育理论和现代信息技术，通过对教学资源的设计、开发、利用、评价和管理，以实现教学最优化的理论和实践．物理学是一门以观察、实验为基础的自然学科，实验教学是物理教学的重要环节．温家宝总理在2005年教师节前夕考察京郊乡村中小学时说：“做学生从小不仅要学会动脑，还要学会动手．过去教育的毛病就是把手、脑分离．我们培养的学生将来不仅要有知识，更重要的是要用这种知识去解决世界上的问题，这就要养成动脑和动手相结合的习惯．”     

基于单通道反射型电光调制器实现不同路光同时调制的方法

提出了一种利用单通道反射型聚合物电光调制器同时调制不同路光的方法。衰减全反射结构的电光调制器,其每一个衰减全反射(ATR)峰的位置分别对应于一个导波共振模式。实验系统中利用衰减全反射导膜峰作为调制通道,使其每一路光路的入射角分别对应于不同导波共振模式的工作角,就可以实现利用单通道的电光调制器同时调制不同路光。提出了三种实现两路光同时调制的模式,并给出了三种模式的调制结果。结果表明,作为调制通道的导模阶数越低,调制效率越高。在832 nm光波波长下,采用最低阶导模进行调制时可以获得42.9%的调制效率。     

Preparation of BA/ST/AM nano particles by ultrasonic emulsifier-free emulsion polymerization

A kind of nano particle of butyl acrylate (BA)/styrene (ST)/acrylamide (AM) was prepared through a new method that was ultrasonic emulsifier-free emulsion polymerization, which was a kind of environmental protection and economical method. And no any volatile organic solvent (VOC), emulsifier and initiator were used in this method. Only water was used as solvent. The effects of sonic intensity, sonic time, inorganic salt content, N2 flow velocity, etc. on monomer conversion were studied. TEM photographs showed that its particles size was about 80 nm, which was less than particles size (about 140 nm) through conventional emulsifier-free emulsion polymerization method. The FTIR spectrum showed that after extracted by water for 48 h, CHCl3 for 48 h and THF for 48 hr, respectively, the sample obtained by this way was a ternary copolymer of BA, ST and AM, but not a blend of poly(butyl acrylate), polystyrene and polyacrylamide.     

Kq, Scaling of ac susceptibility and the nonlinear response function of high-temperature superconductors

The amplitude-dependent ac susceptibility of high-temperature superconductors is shown to obey some empirical scaling relations. We try to analyze this behavior by extending a dc nonlinear response function of mixed state to the ac cases. The derived equations for critical current and ac susceptibility ξ(T) agree with the scaling relations of experimental data.     

Piezoelectric PMN-PT fibre hydrophone for ultrasonic transducer calibration

A newly developed ceramic fibre hydrophone with an active element as small as 0.25 mm in diameter is described in this work. Lead magnesium niobate-lead titanate (PMN-PT) ceramic fibre with a nominal composition of 0.65Pb(Mg_1/3Nb_2/3)O₃-0.35PbTiO₃ was fabricated by an extrusion method. PMN-PT single crystals were ground to a powder form and then mixed with poly(acrylic) acid to form a homogenous slurry. The fibre was extruded by pressing the slurry through a spinneret and then sintering at 1250 °C for crystallization. The electrical characteristics of the PMN-PT fibre were evaluated by measuring the relative permittivity and the impedance spectrum. A piezoelectric PMN-PT fibre hydrophone was fabricated and its sensitivity, angular response, and spatial resolution were evaluated. The fibre hydrophone provides good spatial resolution, angular response and receiving sensitivity. PACS 43.58.+z; 77.84.Dy     

Experimental synchronization of independent entangled photon sources

We report the generation of independent entangled photon pairs from two synchronized but mutually incoherent laser sources. The quality of synchronization is confirmed by observing a violation of Bell's inequality with 3.2 standard deviations in an entanglement swapping experiment. The techniques developed in our experiment are not only important for realistic linear optical quantum-information processing, but also enable new tests of local realism.     

Syntheses, crystal structure and luminescence property of novel 4f-3d heterometallic one-dimensional coordination polymers

Two 4f-3d heterometallic one-dimensional coordination polymers [ZnEu₂(Fur)₈·2H₂O]n and [ZnTb₂(Fur)₈·2H₂O]n (HFur=α-furancarboxylic acid) with good solubility were synthesized and characterized by infrared spectra, X-ray single crystal and powder diffractions, thermogravimetric and differential thermal analysis, and excitation and emission spectra. The X-ray diffraction analyses revealed that the two complexes are isomorphous. The Zn and Ln atoms are linked into one-dimensional chains by furancarboxylate ligands and the metal atoms are arranged in the ···Zn···Ln···Ln···Zn···Ln···Ln···order. Under the excitation of UV light, these coordination polymers emit intense characteristic luminescence of Eu³⁺ or Tb³⁺ ion, respectively. The influence of Zn²⁺ ion on the luminescence properties was also discussed here.     

Ultrasonic treatment on activated sewage sludge from petro-plant for reduction

In this essay, the influences of low frequency ultrasound (20 kHz) on dewater ability and anaerobic digestion behaviors of activated sewage sludge, obtained from Yangzi Water Treatment Plant, Yangzi Petrochemical Corporation, were discussed. Ultrasound pretreatment could enhance the filtration progress and decrease the moisture content of the sludge from 99% to 80%. Together with flocculant, the ultrasound pretreatment decreased the specific filtration resistance (SFR) of the sludge from 3.59 x 10(12) m/kg to 1.18 x 10(12) m/kg and saved about 25-50% of the flocculant dosage. Bound water of the sludge was measured by dilatometer. After 2-4 min treatment of ultrasound under intensity of 400 W/m(2), the bound water of sludge decreased from 16.7 g/g (dry base) to above 2.0 g/g (dry base). Ultrasound pretreatment could also enhance digestion and reduce digestion time. To the same resolution ratio, such as 49%, the digestion time of sludge with ultrasound pretreatment was 7 days less than that without ultrasound. Proper ultrasound pretreatment could also improve the dewater ability of the digested sludge, the final moisture of which was 73.7%.     

Microstructure and wear properties of laser clad Cuss/Cr5Si3 metal silicide composite coatings

Wear resistant Cu-based solid solution (Cu_ss) toughened Cr₅Si₃ metal silicide composite coatings were fabricated on austenitic stainless steel AISI321 by laser cladding process. Due to the rapidly solidified microstructural characteristics and the excellent toughening effect of Cu_ss on Cr₅Si₃, the Cu_ss/Cr₅Si₃ coatings have outstanding wear resistance and low coefficient of friction under room temperature dry sliding wear test conditions coupling with hardened 0.45% C steel.     

Theory of laser acceleration of light-ion beams from interaction of ultrahigh-intensity lasers with layered targets

Experiments at the LANL Trident facility demonstrated the production of monoenergetic ion beams from the interaction of an ultraintense laser with a target comprising a heavy ion substrate and thin layer of light ions. An analytic model is obtained that predicts how the mean energy and quality of monoenergetic ion beams and the energy of substrate ions vary with substrate material and light-ion layer composition and thickness. Dimensionless parameters controlling the dynamics are derived and the model is validated with particle-in-cell simulations and experimental data.