Experimental and theoretical comparison of spatially resolved laser-induced incandescence (LII) signals of soot in backward and right-angle configuration

In-situ measurements of soot volume fraction in the exhausts of jet engines can be carried out using the laser-induced incandescence (LII) technique in backward configuration, in which the signal is detected in the opposite direction of the laser beam propagation. In order to improve backward LII for quantitative measurements, we have in this work made a detailed experimental and theoretical investigation in which backward LII has been compared with the more commonly used right-angle LII technique. Both configurations were used in simultaneous visualization experiments at various pulse energies and gate timings in a stabilized methane diffusion flame. The spatial near-Gaussian laser energy distribution was monitored on-line as well as the time-resolved LII signal. A heat and mass transfer model for soot particles exposed to laser radiation was used to theoretically predict both the temporal and spatial LII signals. Comparison between experimental and theoretical LII signals indicates similar general behaviour, for example the broadening of the spatial LII distribution and the hole-burning effect at centre of the beam due to sublimation for increasing laser pulse energies. However, our comparison also indicates that the current heat and mass transfer model overpredicts signal intensities at higher fluence, and possible reasons for this behaviour are discussed. PACS 42.62.Fi; 44.40.+a     

Pflanzenchemie

Ohne Zusammenfassung     

Coulomb scattering in the eikonal approximation

We derive a new expression for the eikonal approximation of the nuclear Coulomb scattering amplitude. Our expression should be particularly useful for the treatment of Coulomb scattering in hadron-nucleus and nucleus-nucleus scattering at high and intermediate energies.     

Investigation of the cranking model wave function with respect to angular momentum

Projection of angular momentum on cranking model wave functions is performed for some simple cases. An extensive analysis has been possible since an algebraic projection technique is employed and a detailed numerical example is presented. The distribution of angular momentum as a function of rotational frequency and signature is analysed, and special attention is focused on the fact that the signature does not give any strict selection of angular momenta contained in the cranking wave function.     

Solid-Phase Synthesis of a Fragment of the Capsular Polysaccharide of Haemophilus Influenzae Type B Using H-Phosphonate Intermediates

Abstract

A pentameric fragment of the capsular polysaccharide of Haemophilus influenzae type b, containing a linker group, was synthesized by a simple solid-phase procedure. Cross-linked polystyrene was used as a solid phase, and a benzyl-protected ribosylribitol H-phosphonate was used as monomer. A non-promoted glycosidation reaction was used for preparation of the ribosylribitol monomer.     

Analog low-loss full-range phase modulation by utilizing a V-shaped switched ferroelectric liquid-crystal cell in reflective mode

We have studied the analog (V-shaped switching) mode in ferroelectric liquid crystals in reflective mode for analog phase modulation applications. We have found that several combinations of cell thicknesses and input polarization states exist for which near-lossless analog phase modulation with a range of approximately 2pi rad is obtained, and we demonstrate one such combination experimentally. Despite a slight deviation from the ideal conditions, e.g., the tilt angle was 38 degrees instead of the desired 45 degrees , virtually pure 1.6pi rad phase modulation was obtained; the measured values agree very well with our numerical simulations of the real device.     

DWIA analysis of quasifree proton-proton scattering in nuclei at intermediate energies

The distorted wave impulse approximation to the (p, 2p) reaction cross section is briefly reviewed, having foremost in mind its practical implementation as a computer program, suitable for extracting information on nuclear structure. The treatment of the distorted waves, and the approximation of the overlap integral between the ground state of the target nucleus and the final state of the residual nucleus, are discussed in more detail. As far as possible we have chosen methods which enable us to minimize the number of free reaction-theoretical parameters by deducing them from independent experimental data. As an illustration of how one can use a program constructed according to these principles, we analyze 460 MeV and 600 MeV data on the reaction ⁴⁰Ca(p, 2p)³⁹K with rather detailed discussion of various theoretical and experimental questions that must be taken into consideration before any conclusions can be drawn.