The European IST project DAVID: a viable approach toward optical packet switching

In this paper, promising technologies and a network architecture are presented for future optical packet switched networks. The overall network concept is presented and the major choices are highlighted and compared with alternative solutions. Both long and shorter term approaches are considered, as well as both the wide-area network and multiple-area networks parts of the network. The results presented in this paper were developed in the frame of the research project DAVID (Data And Voice Integration over DWDM) project, funded by the European Commission through the IST-framework.     

Biologically Active Natural Acetylenic Compounds from Eutypa lata (Pers: F.) TUL

Eight new acetylenic compounds have been isolated and identified from the culture medium of the fungus Eutypa lata. Structural elucidation and biological activity are discussed.     

Dynamic roughening and fluctuations of dipolar chains

Nonmagnetic particles in a carrier ferrofluid acquire an effective dipolar moment when placed in an external magnetic field. This fact leads them to form chains that will roughen due to Brownian motion when the magnetic field is decreased. We study this process through experiments, theory and simulations, three methods that agree on the scaling behavior over 5 orders of magnitude. The rms width goes initially as t(1/2), then as t(1/4) before it saturates. We show how these results complement existing results on polymer chains, and how the chain dynamics may be described by a recent non-Markovian formulation of anomalous diffusion.     

Coupling semiconductor lasers into single-mode optical fibers by use of tips grown by photopolymerization

We show that a polymer tip, integrated by free-radical photopolymerization at the end of a telecommunication optical fiber, allows high-efficiency coupling between the fiber and an infrared laser diode. A coupling efficiency of 70% (1.5-dB loss) was achieved. We obtained this result by controlling the radius of curvature of the tip, the origin of which is discussed in terms of the photochemical influence of oxygen during tip formation. The experimental data were found to be in agreement with results of electromagnetic calculations based on the finite-element method.     

Oxygen-induced symmetrization and structural coherency in Fe/MgO/Fe(001) magnetic tunnel junctions

We present x-ray diffraction experiments and multiple-scattering calculations on the structure and transport properties of a Fe/MgO/Fe(001) magnetic tunnel junction (MTJ). Coherent growth of the top Fe electrode on the MgO spacer is observed only for Fe deposition in ambient oxygen atmosphere leading to a coherent and symmetric MTJ structure characterized by FeO layers at both interfaces. This goes in parallel with calculations indicating large positive tunnel magnetoresistance (TMR) values in such symmetric junctions. The results have important implications for achieving giant TMR values.     

Microwave-assisted intramolecular Suzuki-Miyaura reaction to macrocycle, a concise asymmetric total synthesis of biphenomycin B

[reaction: see text] A concise and efficient total synthesis of biphenomycin B has been accomplished featuring a key microwave-assisted intramolecular Suzuki-Miyaura reaction for formation of the 15-membered meta,meta-cyclophane 20.     

20 μm单微液滴的产生和特性研究

利用阴影成像法对毛细管喷嘴生成单微液滴的特性进行了观测，研究了单微液滴生成的具体过程，以及气体背压，调制频率和调制电压对单微液滴产生的影响，优化了生成大小和空间分布均匀单微液滴的条件.结果表明：调制频率在0.8—1.8MHz之内，调制电压10V，背推压3.5MPa是获得20μm单微液滴的最佳条件.     

Desymmetrization of 1,4-dien-3-ols and related compounds via Ueno-Stork radical cyclizations

[formula: see text] Desymmetrization of 1,4-dien-3-ols and related compounds via Ueno-Stork radical cyclizations is reported. The stereochemistry of the cyclization is controlled by the acetal center. Excellent stereocontrol at C(4) and C(5) of the newly formed tetrahydrofuran rings is observed. Use of a chiral auxiliary allows the preparation of enantiomerically pure material. The utility of this method has been demonstrated by achieving a short synthesis of (+)-eldanolide, the pheromone of the male African sugarcane stem borer Eldana saccharina.