Kolloidchemie und biomedizinische Anwendung

Diese Arbeit befasst sich mit der kolloidchemischen Charakterisierung und biomedizininischen Anwendung von wirkstoffbeladenen Calciumphosphat-Nanopartikeln. Die Arbeit gliedert sich in drei Abschnitte. Im ersten Teil werden Calciumphosphat-Nanopartikeln mit unterschiedlichen Polymeren stabilisiert und anschließend charakterisiert. Zusätzlich wird die Eignung der unterschiedlich funktionalisierten Partikel als Träger für Nukleinsäuren für die Transfektion untersucht. Des Weiteren wird eine Funktionalisierung solcher Partikel mit Silicumdioxid diskutiert. Im zweiten Teil der Arbeit wird ein nanopartikuläres Trägersystem, das nach dem Layerby-Layer-Verfahren hergestellt wird, synthetisiert und charakterisiert. Außerdem werden Hohlkapseln aus Nanopartikeln, auf die mit dem Layer-by-Layer-Verfahren Polymerschichten aufgebracht werden, durch Herauslösen des Kerns dargestellt. Im dritten Teil der Arbeit geht es um konkrete Anwendungen zweier pastenartiger Formulierungen zur Unterstützung der Heilung von Knochenfrakturen

Analysis and development prospects of electronic and mobile payments in Russia

The article analyses electronic systems development, its impact on the development of the economy and a number of sectors of life. It enumerates and analyses basic forms of ecash circulation. The article demonstrates the need for development of this sphere of economy as well as financial systems

Transversale Entwicklung von Ober- und Unterkieferalveolarfortsätzen bei 7- bis 10-jährigen ostwestfälischen Schulkindern unter Berücksichtigung differenter Angle-Klassen

Ziel der Arbeit ist die Analyse der hinteren Zahnbogenbreite von Ober- und Unterkiefer bei 7- bis 10-jährigen Kindern. Die Querschnittsstudie zeigt: Schon im Alter von 9 Jahren ist sowohl der Oberkiefer als auch der Unterkiefer bei Jungen signifikant breiter als bei Mädchen. Die OK-Breite ist bei Angle-Kl. II-Befunden signifikant kleiner als bei Angle-Kl. I. Im UK sind keine Unterschiede zwischen Kl. I und II feststellbar. Im Verhältnis von OK- zu UK-Breite ist der Unterkiefer, unabhängig vom Angle-Klasse Befund, durchschnittlich zu breit. Die gemessenen OK-Breiten entsprechen in Relation zu den Frontzahnbeiten exakt den Sollwerten nach Schmuth. Die Langzeitstudie zeigt: Die posteriore OK-Breite nimmt vom 7. bis zum 10. Lebensjahr signifikant zu. Im UK erhöht sich die Breite ebenfalls signifikant. Die Differenz zwischen OK- und UK-Breite nimmt bei Jungen signifikant ab, d.h. das Breitenverhältnis der Zahnbögen wird harmonischer. Bei Mädchen bleibt das Breitenverhältnis unverändert

Modeling nonlinear optical interactions of focused beams in bulk crystals and thin films: A phenomenological approach

Coherent nonlinear optical micro-spectroscopy is a frequently used tool in modern material science, as it is sensitive to many different local observables, which comprise, among others, crystal symmetry and vibrational properties. The richness in information, however, may come with challenges in data interpretation, as one has to disentangle the many different effects like multiple reflections, phase jumps at interfaces, or the influence of the Guoy-phase. In order to facilitate interpretation, the work presented here proposes an easy-to-use semi-analytical modeling ansatz, that bases upon known analytical solutions using Gaussian beams. Specifically, we apply this ansatz to compute nonlinear optical responses of (thin film) optical materials. We try to conserve the meaning of intuitive parameters like the Gouy-phase and the nonlinear coherent interaction length. In particular, the concept of coherence length is extended, which is a must when using focal beams. The model is subsequently applied to exemplary cases of second-harmonic and third-harmonic generation. We observe a very good agreement with experimental data and furthermore, despite the constraints and limits of the analytical ansatz, our model performs similarly well as when using more rigorous simulations. However, it outperforms the latter in terms of computational power, requiring more than three orders less computational time and less performant computer systems

Comparing Transmission- and Epi-BCARS: A Transnational Round Robin on Solid State Materials

Broadband coherent anti-Stokes Raman scattering (BCARS) is an advanced Raman spectroscopy method that combines the spectral sensitivity of spontaneous Raman scattering (SR) with the increased signal intensity of single-frequency coherent Raman techniques. These two features make BCARS particularly suitable for ultra-fast imaging of heterogeneous samples, as already shown in biomedicine. Recent studies demonstrated that BCARS also shows exceptional spectroscopic capabilities when inspecting crystalline materials like lithium niobate and lithium tantalate, and can be used for fast imaging of ferroelectric domain walls. These results strongly suggest the extension of BCARS towards new imaging applications like mapping defects, strain, or dopant levels, similar to standard SR imaging. Despite these advantages, BCARS suffers from a spurious and chemically unspecific non-resonant background (NRB) that distorts and shifts the Raman peaks. Post-processing numerical algorithms are then used to remove the NRB and to obtain spectra comparable to SR results. Here, we show the reproducibility of BCARS by conducting an internal Round Robin with two different BCARS experimental setups, comparing the results on different crystalline materials of increasing structural complexity: diamond, 6H-SiC, KDP, and KTP. First, we compare the detected and phase-retrieved signals, the setup-specific NRB-removal steps, and the mode assignment. Subsequently, we demonstrate the versatility of BCARS by showcasing how the selection of pump wavelength, pulse width, and detection geometry can be tailored to suit the specific objectives of the experiment. Finally, we compare and optimize measurement parameters for the high-speed, hyperspectral imaging of ferroelectric domain walls in lithium niobate.Comment: 12 pages, 8 figure

Property Optimization for TWIP Steels – Effect of Pre-deformation Temperature on Fatigue Properties

The current work investigates the impact of pre-deformation temperatures on the microstructure evolution and the subsequent cyclic stress-strain response of high-manganese steel showing twinning-induced plasticity (TWIP) at room temperature (RT). Deformation at low temperatures increases the hardening rate at low to medium degrees of deformation through concurrent martensitic transformation. In contrast, high temperatures promote dislocation slip. Thus, employing pre-treatments at temperatures below and above RT leads to the evolution of considerably different microstructures. Low-cycle fatigue experiments revealed distinct differences for the pre-treated TWIP steels

Tricyanidoferrates(−IV) and ruthenates(−IV) with non‐innocent cyanido ligands

Exceptionally electron-rich, nearly trigonal-planar tricyanidometalate anions [Fe(CN)(3)](7-) and [Ru(CN)(3)](7-) were stabilized in LiSr3[Fe(CN)(3)] and AE(3.5)[M(CN)(3)] (AE=Sr, Ba; M=Fe, Ru). They are the first examples of group 8 elements with the oxidation state of -IV. Microcrystalline powders were obtained by a solid-state route, single crystals from alkali metal flux. While LiSr3[Fe(CN)(3)] crystallizes in P6(3)/m, the polar space group P6(3) with three-fold cell volume for AE(3.5)[M(CN)(3)] is confirmed by second harmonic generation. X-ray diffraction, IR and Raman spectroscopy reveal longer C-N distances (124-128 pm) and much lower stretching frequencies (1484-1634 cm(-1)) than in classical cyanidometalates. Weak C-N bonds in combination with strong M-C pi-bonding is a scheme also known for carbonylmetalates. Instead of the formal notation [Fe-IV(CN-)(3)](7-), quantum chemical calculations reveal non-innocent intermediate-valent CN1.67- ligands and a closed-shell d(10) configuration for Fe, that is, Fe2-