Herstellung und Charakterisierung betulinhaltiger Zubereitungen für berührungsempfindliche Haut

Die vorliegende Arbeit befasst sich mit der Herstellung und Charakterisierung betulinhaltiger Zubereitungen zur berührungsarmen Applikation bei empfindlicher oder geschädigter Haut. In Studien zur Wundheilung wurden positive Ergebnisse mit betulinhaltigen Oleogel-Zubereitungen erzielt, die Anwendung dieser Oleogele gestaltet sich jedoch unkomfortabel. Die Anwendungseigenschaften lassen sich verbessern, wenn man Systeme mit wässriger Außenphase, wie O/W-Emulsionen und Schaumcremes einsetzt, die sich praktisch berührungsfrei auftragen lassen und dadurch Hautreizungen durch mechanische Belastungen auf ein Minimum reduzieren. Die Herstellung und Untersuchung solcher Zubereitungen ist Thema dieser Arbeit. Außerdem erfordert dieses Anwendungsgebiet den Einsatz möglichst weniger und gut verträglicher Hilfsstoffe, zumal bei TE-Oleogelen nur Öl und TE zum Einsatz kommen und durch Wassereinarbeitung ohne weitere Hilfsstoffe eine stabile W/O-Emulsion erhalten werden können. Die Formulierung von betulinhaltigen Systemen mit wässriger Außenphase benötigt jedoch zwangsläufig weitere Hilfsstoffe zur Stabilisierung. Als Wirkstoff wurde mit einem Triterpen-Trockenextrakt (TE) aus dem weißen Kork der Birkenrinde gearbeitet, der zu ca. 85 % aus dem Triterpen Betulin besteht. Es wurden Herstellmethoden und -prozesse entwickelt, mit dem Ziel möglichst kleine TEPartikelgrößenverteilungen in Suspension erzeugen zu können, was sich durch die physikalischen Eigenschaften (plastische Verformbarkeit, geringe Löslichkeit in Wasser und Öl, schlechte Benetzung) des Triperpenextraktes herausfordernd gestaltet. Suspensionen mit möglichst kleinen Partikelgrößen stellten die Basis für die Herstellung von Emulsionen dar. Als Hilfsstoff kamen hierbei hydrokolloide Gelbildner zum Einsatz, da sich der Einsatz von klassischen Emulgatoren aufgrund des irritativen Potentials verbietet. Die Auswahl von Hydroxypropylmethylcellulose als Gelbildner erfolgte nach experimentellem Vergleich mit weiteren Gelbildnern (Na-Alginat, Na-Carboxymethylcellulose, Polyacrylsäure und Xanthangummi), die alle durch ihre gute Hautverträglichkeit auch in Hydrokolloidverbänden Einsatz finden. Hiermit wurden Emulsionen und Schäume mit Propan/Butan-Treibgas hergestellt und die Einflüsse auf die Schaumqualität systematisch untersucht. Hierbei zeigte sich ein Einfluss der Zusammensetzung (HPMC-Anteil, Ölphasenanteil, TE-Anteil, Treibgasdruck und -anteil) auf Schaumdichte, Blasengröße, Zerfallsgeschwindigkeit, Aufschäumgeschwindigkeit und Stabilität. Als Haupteinflussfaktoren auf die Schaumqualität konnten der HPMC-Anteil in positiver und der TE-Anteil in negativer Richtung festgehalten werden. Für das Aufschäumverhalten zeigten sich Treibgasanteil, sowie -druck als entscheidende Faktoren. Außerdem konnten aus dem Versuchsdesign, neben den Einflüssen, optimierte Formulierungen ermittelt werden. Schließlich wurden in-vitro Freisetzungsuntersuchungen mit Franz-Diffusionszellen durchgeführt, um die Freisetzung von Betulin aus Schaumzubereitungen mit der aus Oleogelen zu vergleichen. Hierbei wurde aus den Schäumen eine geringere Freisetzung als aus vergleichbaren Oleogelen festgestellt. Ein weiterer Formulierungsansatz wurde mit Submikronemulsionen verfolgt. Hierbei konnten Emulsionen erhalten werden, deren Tröpfchen und Partikel deutlich unterhalb von einem Mikrometer Größe lagen - ein Aufschäumen der Emulsionen war allerdings nicht möglich. Zur Aufklärung eines Einflusses der TE-Partikel auf die Stabilisierung in diesen Systemen wurden Tropfenprofilanalysemessungen durchgeführt, wobei ein stabilisierender Einfluss des TE durch eine ausgeprägtere Elastizität der Grenzfläche festgestellt werden konnte

Operations plans and sensitivities of the IceCube Upgrade Camera System

The IceCube Upgrade consists of seven new strings to be deployed in the central region of the existing IceCube detector. The goals of the IceCube Upgrade are two-fold: to enhance sensitivity to neutrinos in the GeV range, and to improve the calibration of the IceCube detector as a means of reducing systematic uncertainties due to the optical properties of the ice. Among other calibration devices designed to study ice properties, a novel camera system will be deployed as part of the Upgrade. The system will include three cameras, each paired with an illumination LED, included in each of the Upgrade optical modules. In total, 2,300 cameras will be deployed. A combination of photographic images from transmitted and reflected light will measure optical properties of both the bulk ice in-between strings and the local ice refrozen in the drill hole. In this contribution, we present the operations plans for these two types of measurements and the sensitivities to the ice properties and geometry of the new modules that can be achieved with the new camera system.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023). See arXiv:2307.13047 for all IceCube contribution

Effects of impurity scattering on electron-phonon resonances in semiconductor superlattice high-field transport

A non-equilibrium Green's function method is applied to model high-field quantum transport and electron-phonon resonances in semiconductor superlattices. The field-dependent density of states for elastic (impurity) scattering is found non-perturbatively in an approach which can be applied to both high and low electric fields. I-V curves, and specifically electron-phonon resonances, are calculated by treating the inelastic (LO phonon) scattering perturbatively. Calculations show how strong impurity scattering suppresses the electron-phonon resonance peaks in I-V curves, and their detailed sensitivity to the size, strength and concentration of impurities.Comment: 7 figures, 1 tabl

Valuation of Life Among Old and Very Old Adults: Comparison Between Germany and Japan

Background and Objectives: Valuation of life (VOL) represents a construct capturing individuals’ active attachment to their life. The majority of studies on VOL were conducted in North America and Europe where personal autonomy and independence are highly valued, leaving open the question about the relevance of this construct in interdependence-oriented cultures. Using a framework of cross-cultural and life-span theories, the present study compared levels and predictors of VOL between the young-old and old-old individuals from Germany and Japan. Research Design and Methods: Two hundred fifty-seven Germans and 248 Japanese, matched by age, gender, education, and IADL, answered a 5-item VOL scale and shared information on sociodemographic, social, and health resources. Results: Germans’ VOL levels were higher than in Japanese participants. Both culture- and age-moderated predictions of VOL: education was significant only in the young-old Japanese, and close social partners mattered in the old-old, not in the young-old. Health determined VOL irrespective of culture and age. Discussion and Implications: The findings suggest that cultural values and aging processes should be considered to better understand how individuals value their life and to help older adults to feel that his/her life is meaningful and worth living

Co-sputtered PtMnSb thin films and PtMnSb/Pt bilayers for spin-orbit torque investigations

The manipulation of the magnetization by spin-orbit torques (SOTs) has recently been extensively studied due to its potential for efficiently writing information in magnetic memories. Particular attention is paid to non-centrosymmetric systems with space inversion asymmetry, where SOTs emerge even in single-layer materials. The half-metallic half-Heusler PtMnSb is an interesting candidate for studies of this intrinsic SOT. Here, we report on the growth and epitaxial properties of PtMnSb thin films and PtMnSb/Pt bilayers deposited on MgO(001) substrates by dc magnetron co-sputtering at high temperature in ultra-high vacuum. The film properties were investigated by X-ray diffraction, X-ray reflectivity, atomic force microscopy, and electron microscopy. Thin PtMnSb films present a monocrystalline C1b phase with (001) orientation, coexisting at increasing thickness with a polycrystalline phase with (111) texture. Films thinner than about 5 nm grow in islands, whereas thicker films grow ultimately layer-by-layer, forming a perfect MgO/PtMnSb interface. The thin PtMnSb/Pt bilayers also show island growth and a defective transition zone, while thicker films grow layer-by-layer and Pt grows epitaxially on the half-Heusler compound without significant interdiffusion. (C) 2017 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim</p

Sign change in the tunnel magnetoresistance of Fe3O4/MgO/Co-Fe-B magnetic tunnel junctions depending on the annealing temperature and the interface treatment

Magnetite (Fe3O4) is an eligible candidate for magnetic tunnel junctions (MTJs) since it shows a high spin polarization at the Fermi level as well as a high Curie temperature of 585{\deg}C. In this study, Fe3O4/MgO/Co-Fe-B MTJs were manufactured. A sign change in the TMR is observed after annealing the MTJs at temperatures between 200{\deg}C and 280{\deg}C. Our findings suggest an Mg interdiffusion from the MgO barrier into the Fe3O4 as the reason for the change of the TMR. Additionally, different treatments of the magnetite interface (argon bombardment, annealing at 200{\deg}C in oxygen atmosphere) during the preparation of the MTJs have been studied regarding their effect on the performance of the MTJs. A maximum TMR of up to -12% could be observed using both argon bombardment and annealing in oxygen atmosphere, despite exposing the magnetite surface to atmospheric conditions before the deposition of the MgO barrier.Comment: 5 pages, 5 figures, 2 table

Differential effects of α4β7 and GPR15 on homing of effector and regulatory T cells from patients with UC to the inflamed gut in vivo

Objective: Gut homing of lymphocytes via adhesion molecules has recently emerged as new target for therapy in inflammatory bowel diseases. We aimed to analyze the in vivo homing of effector (Teff) and regulatory (Treg) T cells to the inflamed gut via α4β7 and GPR15. Design: We assessed the expression of homing receptors on T cells in peripheral blood and inflamed mucosa. We studied the migration pattern and homing of Teff and Treg cells to the inflamed gut using intravital confocal microscopy and FACS in a humanized mouse model in DSS-treated NSG (NOD.Cg-Prkdcscid-Il2rgtm1Wjl/SzJ) mice. Results: Expression of GPR15 and α4β7 was significantly increased on Treg rather than Teff cells in peripheral blood of patients with ulcerative colitis (UC) as compared to Crohn´s disease and controls. In vivo analysis in a humanized mouse model showed augmented gut homing of UC Treg cells as compared to controls. Moreover, suppression of UC (but not control) Teff and Treg cell homing was noted upon treatment with the α4β7 antibody vedolizumab. In contrast, siRNA blockade of GPR15 had only effects on homing of Teff cells but did not affect Treg homing in UC. Clinical vedolizumab treatment was associated with marked expansion of UC Treg cells in peripheral blood. Conclusion: α4β7 rather than GPR15 is crucial for increased colonic homing of UC Treg cells in vivo, while both receptors control UC Teff homing. Vedolizumab treatment impairs homing of UC Treg cells leading to their accumulation in peripheral blood with subsequent suppression of systemic effector T cell expansion

Sign change in the tunnel magnetoresistance of Fe3O4/MgO/Co-Fe-B magnetic tunnel junctions depending on the annealing temperature and the interface treatment

Marnitz L, Rott K, Niehörster S, et al. Sign change in the tunnel magnetoresistance of Fe3O4/MgO/Co-Fe-B magnetic tunnel junctions depending on the annealing temperature and the interface treatment. AIP Advances. 2015;5(4): 047103.Magnetite (Fe3O4) is an eligible candidate for magnetic tunnel junctions (MTJs) since it shows a high spin polarization at the Fermi level as well as a high Curie temperature of 585°C. In this study, Fe3O4/MgO/Co-Fe-B MTJs were manufactured. A sign change in the TMR is observed after annealing the MTJs at temperatures between 200°C and 280°C. Our findings suggest an Mg interdiffusion from the MgO barrier into the Fe3O4 as the reason for the change of the TMR. Additionally, different treatments of the magnetite interface (argon bombardment, annealing at 200°C in oxygen atmosphere) during the preparation of the MTJs have been studied regarding their effect on the performance of the MTJs. A maximum TMR of up to -12% could be observed using both argon bombardment and annealing in oxygen atmosphere, despite exposing the magnetite surface to atmospheric conditions before the deposition of the MgO barrier