用于接触式探测的多模光纤探针形状优化

对于进行接触式探测的多模光纤探针,信号光来自于附着于探针表面的待测物。基于几何光学,提出了一个物理模型,用以分析探头形状对所收集的信号光强度的影响。采用此模型,对抛物线型探头进行了仿真,给出了最优形状参数,并采用表面增强拉曼探针进行了初步实验验证。此分析可用于指导各种光纤传感器的设计,以确定其最佳的形状参数,适用于荧光传感器、表面等离子体共振传感器、表面增强拉曼传感器等。     

A multiscale poromicromechanical approach to wave propagation and attenuation in bone

Ultrasonics is an important diagnostic tool for bone diseases, as it allows for non-invasive assessment of bone tissue quality through mass density–elasticity relationships. The latter are, however, quite complex for fluid-filled porous media, which motivates us to develop a rigorous multiscale poromicrodynamics approach valid across the great variety of different bone tissues. Multiscale momentum and mass balance, as well as kinematics of a hierarchical double porous medium, together with Darcy’s law for fluid flow and micro–poro-elasticity for the solid phase of bone, give access to the so-called dispersion relation, linking the complex wave numbers to corresponding wave frequencies. Experimentally validated results show that 2.25 MHz acoustical signals transmit healthy cortical bone (exhibiting a low vascular porosity) only in the form of fast waves, agreeing very well with experimental data, while both fast and slow waves transmit highly osteoporotic as well as trabecular bone (exhibiting a large vascular porosity). While velocities and wavelengths of both fast and slow waves, as well as attenuation lengths of slow waves, are always monotonously increasing with the permeability of the bone sample, the attenuation length of fast waves shows a minimum when considered as function of the permeability.     

A cationic, four-coordinate, ten-electron bismuth(III) complex: Synthesis and structure of [BiPh2(HMPA)2][BF4] (HMPA = hexamethylphosphoramide)

The synthesis and structure of the cationic, four-coordinate, ten-electron bismuth(III) complex [BiPh₂(HMPA)₂]⁺ (HMPA = hexamethylphosphoramide) is reported. The coordination geometry around the bismuth centre is that of a trigonal bipyramid with one equatorial site vacant and with phenyls in the other equatorial positions and the HMPA ligands in axial sites.     

The rapid formation of tin oxide pillared laponite by microwave heating: Characterisation by tin-119 Mössbauer spectroscopy,X-ray photoelectron spectroscopy and nuclear magnetic resonance

The intercalation of organotin-compounds into laponite and the formation of tin(IV) oxide pillars is rapidly achieved when performed in a microwave oven.¹¹⁹Sn Mössbauer- and x-ray- photoelectron-spectroscopy suggest that Ph₃SnCl and Ph₂SnCl₂ undergo hydrolysis on the surface once sorbed. The treatment of Ph₃SnCl/laponite with microwave radiation also induces the formation of a metallic phase which contains both tin and magnesium.     

A hetero Diels-Alder approach to the synthesis of the first angucyclinone and angucycline 5-aza-analogues

The synthesis of two new heterodienes and their regioselective [4+2]cycloaddition reactions with several bromo-naphthoquinones allowed us to prepare the first angucyclinone and angucycline 5-aza-analogues.     

Vibrational spectroscopy of solid state molecular dimers

The IR and Raman spectra of α- and β-perylene crystal vibrations are investigated, β-perylene is monomeric and α-perylene has face-to-face dimers. Frequencies and forms of the lattice vibrations as well as vibron relaxation and localization are discussed. Polarization ratios in α crystals are perturbed by coupling to dimer vibrations.     

Facilitated modelling with discrete-event simulation: Reality or myth?

Is it possible for discrete-event simulation to be used in a facilitated workshop environment? Over the last decade there have been various attempts to use simulation in this way, but we argue here that none have been successful in achieving a fully facilitated mode where the model is both developed and used in the workshop. We attempt to use a discrete-event simulation in a facilitated mode as part of a lean improvement workshop in a hospital setting. The model was successfully developed and used within the 3 day period of the workshop. Although the intervention was successful, we still had to build the model in the ‘back-office’, meaning that a fully facilitated mode was not achieved. The paper concludes by discussing how fully facilitated modelling with discrete-event simulation might be made possible; the answer is more about changing mind-sets than about technological challenge.