An experimental examination of an impulsively started incompressible turbulent jet

The transient morphology and entrained fluid distribution of an impulsively started turbulent jet are studied in an experiment that examines a jet of dyed water injected into a large water reservoir. The images obtained, using a video recorder, are processed to determine the time-dependent length, tip velocity, and volume of the jet. Abel inversion is used in conjunction with digital images to examine the transient distribution of the ambient fluid entrained into the jet. Results from the analysis also describe the self-similarity of the jet’s flow and entrainment.     

A shifted‐excitation Raman difference spectroscopy (SERDS) evaluation strategy for the efficient isolation of Raman spectra from extreme fluorescence interference

A biochemical characterization of pathologies in biological tissue can be provided by Raman spectroscopy. Often, the raw spectrum is severely affected by fluorescence interference. We report and compare various spectra‐processing approaches required for the purification of Raman spectra from heavily fluorescence‐interfered raw spectra according to the shifted‐excitation Raman difference spectroscopy method. These approaches cover the entire spectra‐processing chain from the raw spectra to the purified Raman spectra. In detail, we compared (1) area normalization versus z‐score normalization, (2) direct reconstruction of the difference spectra versus reconstruction of zero‐centered difference spectra and (3) collective baseline correction of the reconstructed spectra versus piecewise baseline correction of the reconstructed spectra and, finally, (4) analyzed the influence of the shift of the excitation wavelength on the quality of the reconstructed spectra. Statistical analysis of the spectra showed that – in our experiments – the best results were obtained for the z‐score normalization before subtraction of the normalized spectra, followed by zero‐centering of the difference spectra before reconstruction and a piecewise baseline correction of the pure Raman spectra. With our equipment, a wavelength shift from 784 to 785 nm provided reconstructed spectra of best quality. The analyzed specimens were different tissue types of pigs, tissue from the oral cavity of humans and a model solution of dye dissolved in ethanol. © 2015 The Authors. Journal of Raman Spectroscopy published by John Wiley & Sons Ltd.     

Electron detachment and fragmentation in collisions between 1.25 keV/carbon and clusters and

The destruction cross-section for 22.5 and 50 keV C^1- , for 10 and 50 keV C₈ ^1- and for 50 and 75 keV C₆₀ ^1- clusters in collisions with H₂ has been measured by an attenuation method. The destruction of the cluster anions is dominated by electron detachment rather than fragmentation and is of the order of the geometric cross-section. The cross-sections vary little with bombarding energy. Received: 16 September 1998 / Received in final form: 23 February 1999     

Evidence for non-axial shapes in81, 82, 83Kr

Excitations up to I=12 have been found in⁸²Kr during an (α, 2n) in-beam experiment. Several levels are interpreted as due to (g9/2)² neutron excitations. A comparison with g9/2 neutron bands in^{81, 83}Kr and with cranked shell model calculations indicates non-axial deformation in connection with a rotation-aligned band starting with an 8⁺ level. Non-collective excitations, 8⁺ (and 6⁺), have been interpreted as deformation-aligned two-neutron states.