Novel formulations of vitamins and insulin by nanoengineering of polyelectrolyte multilayers around microcrystals

Microcapsules loaded with vitamin K3 (VK3), biotin, or insulin were prepared by using a novel coating technology based on the layer-by-layer (LbL) deposition of oppositely charged polyelectrolytes onto microcrystal templates. This produced multilayered, polymeric shells of varying thickness around the crystalline cores. Dissolution of the core material (VK3 with ethanol, biotin with basic solution, and insulin with acidic solution), resulted in its release through the shells. Microelectrophoresis was employed to monitor the microcrystal coating process; confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) were used to verify multilayer coating and the formation of hollow polymer shells following removal of the microcrystal templates. The release rates of both VK3 and insulin decreased as the wall thickness (the number of polyelectrolyte layers deposited onto the microcrystal cores), increased. The release time could be varied by a factor of more than ten, depending on the number of polyelectrolyte layers applied. Following the addition of 70 mass % ethanol, the solubility of VK3 increased by as much as 170-fold, resulting in an increased rate of VK3 release. By selecting appropriate polymer materials for the shells, and by controlling the number of polyelectrolyte layers applied, shells of various thickness, stiffness, aqueous solubility, dispersibility, biocompatibility, and permeability can be constructed.     

Isotope shift in molybdenum

The isotope shift in molybdenum has been studied in 16 lines of the arc and 6 lines of the spark spectrum for all stable isotopes by means of a photoelectric recording Fabry-Perot spectrometer with digital data processing. Mass shift and field shift were separated by two independent methods and were compared with the results of Hartree-Fock calculations. In the field shift large crossed-second-order effects ind ⁵ s ⁷ S and⁵ S were observed, which could be explained quantitatively by theory. The changes in mean square nuclear charge radii were evaluated from three 5s-5p transitions between different multiplets. The relativeδ〈r ² 〉 values are: [92, 94] 1; [94, 96] 0.854(3); [96, 98] 0.665(4); [98, 100] 1.003(5); [95, 97] 0.703(5);. [94, 95] 0.270(4); [96, 97] 0.119(5). The absolute values can be obtained withδ〈r ² 〉 ^{92, 94}=0.226(19)fm².     

Zeemaneffektuntersuchungen im Er I

Zeeman effect investigations in Er I were made in the 3000 to 5000 Å range at field strengths of about 26 kOe. A total of 74g _J-values were determined. Theg _J-values for 11 levels of the configuration 4f ¹¹ 5d 6s ² and for 4 levels of 4f ¹² 6s ² are compared with theoretical values calculated by other authors.     

Shock wave propagation in a branched duct

The propagation of a planar shock wave in a 90° branched duct is studied experimentally and numerically. It is shown that the interaction of the transmitted shock wave with the branching segment results in a complex, two-dimensional unsteady flow. Multiple shock wave reflections from the duct's walls cause weakening of transmitted waves and, at late times, an approach to an equilibrium, one-dimensional flow. While at most places along the branched duct walls calculated pressures are lower than that existing behind the original incident shock wave, at the branching segment's right corner, where a head on-collision between the transmitted wave and the corner is experienced, pressures that are significantly higher than those existing behind the original incident shock wave are encountered. The numerically evaluated pressures can be accepted with confidence, due to the very good agreement found between experimental and numerical results with respect to the geometry of the complex wave pattern observed inside the branched duct. Received 15 July 1996 / Accepted 20 February 1997     

Optical properties and morphology of thin diindenoperylene films

Thin films of diindenoperylene deposited on weakly interacting substrates (quartz) are characterized with scanning probe microscopy techniques at room temperature and by pico-second time-resolved fluorescence spectroscopy between 5 and 300 K. Pronounced T-dependencies of fluorescence spectra and decays are found. The interplay between two fluorescence series in a narrow temperature range has been spectrally and temporally resolved. The possible origin of the observed series, competing energy transfer and quenching processes is discussed.     

Zeemaneffektuntersuchungen im Samarium I-Spektrum

Zeeman effect investigations in Sm I were made in the 3350 to 6700 Å range at field strengths of approximately 25 kOe. 26J-values of those terms, for whichAlbertson gave twoJ-values, were determined, 4J-values ofAlbertson had to be changed. 28g_J-values were measured.