摘要:
A hydrogenation catalyst, preferably palladium on a support, preferably alumina or activated charcoal support, is used in the presence of lithium salts, with salts such as the borates being preferred. This provides hydrogenation of precursors to give rise to a stereoselective, such as diastereoselective bias in the product of alkene hydrogenation using the catalyst.
摘要:
A hydrogenation catalyst, preferably palladium on a support, preferably alumina or activated charcoal support, is used in the presence of lithium salts, with salts such as the borates being preferred. This provides hydrogenation of precursors to give rise to a stereoselective, such as diastereoselective bias in the product of alkene hydrogenation using the catalyst.
摘要:
In a process for the hydroformylation of alkanes, alkenes or trialkylboranes under supercritical or near-critical conditions, hydroformylation is effected using a heterogeneous catalyst in a continuous flow reactor containing a supercritical or near-critical reaction medium. Selectivity of product formation may be achieved by independently varying one or more of the temperature, pressure, catalyst, mole ratios of hydrogen and carbon monoxide and flow rate.
摘要:
A phase modulator includes a lower layer of glass or silicon substrate containing a 1-D array of pixels (42) formed from either ITO or aluminium respectively. The substrate is covered by an upper glass plate coated uniformly with ITO to make one large transparent electrode. Polymer-dispersed LC composite material is sandwiched between these layers, the polymer-dispersed material containing a nematic LC (with positive dielectric). Figure 4a shows the bipolar director configuration within the droplets (40) in the field-off condition where the bipolar axis of each droplet is assumed to be randomly oriented. Light impinging on this material may encounter small enough scattering centres to be suitable for Rayleigh scattering. An applied electric field exerts an electric torque on the directors. This is balanced by an elastic torque generated by the distortion of the director pattern away from its equilibrium position. The balance of these two forces determines an equilibrium position of the director and a rotation of the bipolar axis towards an orientation normal to the plane of the SLM. The device is thus able to provide an analogue modulation of the refractive index, and hence phase delay, encountered by incoming light. Figure 4b shows the final switch configuration in which voltages of different magnitudes have been applied to different pixels (42) to produce several different regions (44) of PDLC, with different switch states, and hence a phase pattern suitable to defract light into first order spot with high efficiency.
摘要:
Apparatus and methods are described for calibrating an optical system having a Spatial Light Modulator, SLM, the method comprising a comparison of: a phase and/or amplitude distribution of at least one beam incident on the SLM, this phase and/or amplitude distribution measured by means of phase modulating elements on the SLM; with at least one known feature of the beam.
摘要:
An optical switch uses two ferroelectric liquid crystal spatial light modulators (10, 11) with an interconnect region in between. The switch uses bulk lenses (2, 8) to focus light from an input fibre array (1) to a first spatial light modulator (10), and from the second spatial light modulator (11) to an output array (9). Each spatial light modulator displays a respective hologram selected from a previously calculated set, to cause a desired switching of light from the input fibre array to the output array.
摘要:
Die Erfindung betrifft Mischungen schwefelhaltiger Triazinverbindungen und Verfahren zur Herstellung dieser Verbindungen mit der allgemeinen Formel in welcher bedeuten: R1 , R 2 = H, R 2 = Benzyl, R 2 , R 3 , R 4 = C 1 -C 8 -Alkyl, Allyl, C 3 -C 8 Cycloalkyl, letzteres unsubstituiert oder mit 1-3 Methylgruppen substituiert, 2-Hydroxiethyl, 3-Hydroxipropyl, 2-Hydroxipropyl oder R 3 und R 4 (zusammen): C 4 -C 6 -Alkylen,-(CH 2 -CHX) 2 Y mit X = H, CH 3 , Y = O,S, S a : Polysulfankette mit 2-10 S-Atomen (d.h. 2 ≦ a ≦ 10), wobei die einzelnen Polysulfane in solchen Konzentrationen vorliegen, daß das statistische Mittel a ganze oder gebrochene Zahlenwerte von 2 bis 5 annimmt, dadurch gekennzeichnet, daß man eine Triazinverbindung der allgemeinen Formel mit einer in einem protischen, polaren, Lösungsmittel, insbesondere Wasser, gelösten Ammonium-oder Alkalipolysulfid bei einer Temperatur von 80 bis 140°C umsetzt.