Fließfähigkeit und kritisches Pigmentvolumen in der Anstrichmittelindustrie

Ohne ZusammenfassungVortrag gehalten auf dem Herbert Freundlich-Gedächtnis-Korigreß in Berlin vom 5. bis 8. Mai 1954.     

Dual-color fluorescence cross-correlation spectroscopy on a planar optofluidic chip

Fluorescence cross-correlation spectroscopy (FCCS) is a highly sensitive fluorescence technique with distinct advantages in many bioanalytical applications involving interaction and binding of multiple components. Due to the use of multiple beams, bulk optical FCCS setups require delicate and complex alignment procedures. We demonstrate the first implementation of dual-color FCCS on a planar, integrated optofluidic chip based on liquid-core waveguides that can guide liquid and light simultaneously. In this configuration, the excitation beams are delivered in predefined locations and automatically aligned within the excitation waveguides. We implement two canonical applications of FCCS in the optofluidic lab-on-chip environment: particle colocalization and binding/dissociation dynamics. Colocalization is demonstrated in the detection and discrimination of single-color and double-color fluorescently labeled nanobeads. FCCS in combination with fluorescence resonance energy transfer (FRET) is used to detect the denaturation process of double-stranded DNA at nanomolar concentration.     

Spatial release from speech-on-speech masking in the median sagittal plane

Several studies have described a release from speech-on-speech masking associated with separation of target and masker sources in the median sagittal plane. Some have excluded the possibility that small differences between target and masker interaural time disparities can fully account for this release. This study explored the mechanisms underlying the spatial release from speech-on-speech masking that can be obtained in the absence of such differences. In one condition, interaural time disparities were removed from the nominal median-sagittal-plane, head-related impulse responses used to generate the virtual auditory space within which competing sentences were presented. In other conditions, interaural level and spectral disparities also were manipulated by presenting competing sentences monaurally or diotically after convolution with one ear's head-related impulse responses. It was found that substantial spatial release from masking can be obtained in the absence of any interaural disparities and that such disparities probably make a relatively minor contribution to spatial release from speech-on-speech masking in the median sagittal plane. It is argued that this release from masking is driven primarily by a reduction in informational masking that occurs when monaural information at one, or both, of the listener's ears facilitates differentiation of competing sentences that emanate from spatially separated sources.     

Continuous-wave nonclassical light with gigahertz squeezing bandwidth

Squeezed states can be employed for entanglement-based continuous-variable quantum key distribution, where the secure key rate is proportional to the bandwidth of the squeezing. We produced a nonclassical cw laser field at the telecommunication wavelength of 1550 nm, which showed squeezing over a bandwidth of more than 2 GHz. The experimental setup used parametric downconversion via a periodically poled potassium titanyl phosphate crystal. We did not use any resonant enhancement for the fundamental wavelength, which should in principle allow a production of squeezed light over the full phase-matching bandwidth of several nanometers. We measured the squeezing to be up to 0.3 dB below the vacuum noise from 50 MHz to 2 GHz limited by the measuring bandwidth of the homodyne detector. The squeezing strength was possibly limited by thermal lensing inside the nonlinear crystal.