Optical detection of elastodynamic fields of ultrasonic transducers

By applying diffraction grids to the detection surface the full vector content of the elastic wave field of ultrasonic transducers can be measured using common heterodyne interferometers. The signal to noise ratio is good enough to detect even small edge wave contributions to the elastic wave field. Numerical simulation of the elastic wave propagation by the elastodynamic finite integration technique helps to understand the origin of several field components observed in the measurements.     

Die Abtrennung des metachromatischen Bestandteils von Methylenblau und Chondroitinsulfat durch Ultrazentrifugation

Ohne Zusammenfassung     

The Time-space-dependent Power Spectrum for the Description of Nonstationary and Inhomogeneous Electromagnetic Fields

The nonstationary analogue to the stationary Wiener Khintchine theorem is considered and applied to the multi-dimensional case of temporally nonstationary and spatially inhomogeneous electromagnetic fields. The time-space-dependent power spectrum of these fields is introduced, and its connection with important measurable quantities is discussed. The dispersions relations (the mutual dependence of the Fourier variables ω, k belonging to the time and space coordinates t, ??) are included into the consideration. The variable Fourier amplitudes are compared with the conventionally used slowly varying field amplitudes. The transition to the stationary limiting case is carried out.     

Omnidirectional reflector using nanoporous SiO2 as a low-refractive-index material

Triple-layer omnidirectional reflectors (ODRs) consisting of a semiconductor, a quarter-wavelength transparent dielectric layer, and a metal have high reflectivities for all angles of incidence. Internal ODRs (ambient material's refractive index n > 1.0) are demonstrated that incorporate nanoporous SiO2, a low-refractive-index material (n = 1.23), as well as dense SiO2 (n = 1.46). GaP and Ag serve as the semiconductor and the metal layer, respectively. Reflectivity measurements, including angular dependence, are presented. Calculated angle-integrated TE and TM reflectivities for ODRs employing nanoporous SiO2 are R(int)/TE = 99.9% and R(int)/TM = 98.9%, respectively, indicating the high potential of the ODRs for low-loss waveguide structures.     

Solvent-induced morphological transition in core-cross-linked block copolymer micelles

Microwave-assisted polymerization has been utilized to synthesize amphiphilic poly(2-ethyl-2-oxazoline-block-2-"soy alkyl"-2-oxazoline) diblock copolymers (PEtOx-PSoyOx). The amphiphilic block copolymers have been used to prepare aqueous spherical micelles consisting of a PEtOx corona and a PSoyOx core, which have been further cross-linked by UV irradiation. The morphology of these cross-linked micelles has been shown to reversibly change from spheres to short rods referred to as rice grains whenever the micelles were transferred from water into acetone, a nonselective solvent for the constituent blocks. This morphological transition has been attributed to the swelling of the slightly cross-linked PSoyOx core.     

Darstellung von Acetatoblei(IV)- und Acetatozinn(IV)- manganpentacarbonylen durch Acidolyse von (C6H5)4–n−M[Mn(CO)5]n (M  Sn,Pb; n = 1, 2) mit Essigsäure

Preparation of Acetatolead(1V) and Acetatotin(1V) Manganese Pentacarbonyls by Acidolysis of (C₆H₅)_4?n M[Mn(CO)₅]_n (M ? Sn, Pb; n = 1, 2) with Acetic Acid By acidolysis of (C₆H₅)_4?nM[Mn(CO)₅]_n (M ? Sn, Pb; n = 1, 2) with acetic acid no M? Mn bonds are broken, but M? C bonds. In this reaction (CH₃COO)₂M[Mn(CO)₅]₂ is formed from (C₆H₅)₂M[Mn(CO)₅]₂, and (CH₃COO)₃SnMn(CO)₅ and (CH₃COO)₂C₆H₅PbMn(CO)₅ from (C₆H₅)₃MMn-(CO)₅. (CH₃COO)₂C₆H₅SnMn(CO)₅ is prepared from Cl₂C₆H₅SnMn(CO)₅ and AgCH₃COO. According to IR spectroscopic data the acetato ligands of the diacetato complexes are bidentate, while in (CH₃COO)₃SnMn(CO)₅ bi- and monodentate carboxylate groups are present. For the central atoms Sn and Pb octahedral coordination is proposed.