19 research outputs found
Molecular beam epitaxy of high structural quality Bi2Se3 on lattice matched InP(111) substrates
Epitaxial layers of the topological insulator Bi2Se3 have been grown by
molecular beam epitaxy on laterally lattice-matched InP(111)B substrates. High
resolution X-ray diffraction shows a significant improvement of Bi2Se3 crystal
quality compared to layers deposited on other substrates. The measured full
width at half maximum of the rocking curve is Delta omega=13 arcsec, and the
(omega-2theta) scans exhibit clear layer thickness fringes. Atomic force
microscope images show triangular twin domains with sizes increasing with layer
thickness. The structural quality of the domains is confirmed on the
microscopic level by transmission electron microscopy.Comment: 4 pages, 4 figure
Evaluierung der neurokognitiven VerÀnderungen nach Cochleaimplantation
Hintergrund: Die Wechselwirkung zwischen Kognition und Hören wird seit langer Zeit diskutiert. Im Hinblick auf die demographische Entwicklung und die rasante Zunahme an dementiellen Erkrankungen gewinnt diese Frage zunehmend an Bedeutung. Im Rahmen einer prospektiven Untersuchung wurden die kognitiven FĂ€higkeiten vor und 6 Monate nach einer Cochleaimplantation evaluiert.Material und Methoden: 70 Patienten mit einer beidseitigen hochgradigen Hörstörung (mittleres Alter 67 Jahre), die sich ab 01/2016 zu einer CI-Operation in der Klinik fĂŒr HNO-Heilkunde der Ruhr-UniversitĂ€t Bochum vorstellten, wurden prĂ€operativ sowie 6 Monate postoperativ mit Hilfe einer computerbasierten Testbatterie untersucht. Diese beinhaltete neben exekutiven Funktionen wie dem ArbeitsgedĂ€chtnis, der Inhibition und den Wechselkosten die Aufmerksamkeit, das Erinnern, das verzögerte Erinnern sowie das Kurz- und LangzeitgedĂ€chtnis. Daneben wurden verschiedene Fragebögen zur allgemeinen LebensqualitĂ€t, zum Hören, zu Copingstrategien sowie zu vorliegenden psychiatrischen Erkrankungen und ein Intelligenztest erhoben.Ergebnisse: Die Aufmerksamkeit, erfasst durch den M3, verbesserte sich signifikant in der Gesamt IE (pw=0,00007). Dabei nahm die Reaktionszeit im Median von 807,13 ms auf 725,57 ms ab und die Anzahl der richtig gelösten Aufgaben von 78 auf 88,5 zu. Im einfachen und im verzögerten Erinnern lieĂ sich keine signifikante VerĂ€nderung aufzeigen. Das ArbeitsgedĂ€chtnis gemessen am n-back und OSPAN zeigte signifikante Verbesserungen nach 6 Monaten (pw=0,0053 und pw=0,00012). Vor allem lag dies an einer Verbesserung der Reaktionszeit im two-back sowie der Anzahl der richtig erinnerten Items im OSPAN. Die Anzahl richtig gelöster Rechenaufgaben verĂ€nderte sich nur geringfĂŒgig. Ebenso konnten die Patienten signifikant besser auf kompatible und inkompatible Reize reagieren (pw=0,00092). Auch die WortflĂŒssigkeit nahm signifikant zu (pw=0,0031). Sowohl der Flanker als Test fĂŒr die Inhibition als auch der M3, der die Aufmerksamkeit ĂŒberprĂŒfte, wiesen eine AltersabhĂ€ngigkeit auf.Eine signifikante Korrelation zwischen dem p.o. Sprachverstehen, gemessen am Freiburger Einsilber bei 65 und bei 80 dB, und den neurokognitiven FĂ€higkeiten fand sich bis auf die p.o. Wortfindung (ptau=0,013) nicht.Diskussion: Die vorlĂ€ufigen Ergebnisse deuten darauf hin, dass sich die kognitiven FĂ€higkeiten nach einer Cochleaimplantation verbessern. Ob sich durch eine Hörrehabilitation der kognitive Abbau im Alter beeinflussen lĂ€sst, mĂŒssen Langzeitstudien zeigen
Picturing of the Lung Tumor Cellular Composition by Multispectral Flow Cytometry
The lung tumor microenvironment plays a critical role in the tumorigenesis and metastasis of lung cancer, resulting from the crosstalk between cancer cells and microenvironmental cells. Therefore, comprehensive identification and characterization of cell populations in the complex lung structure is crucial for development of novel targeted anti-cancer therapies. Here, a hierarchical clustering approach with multispectral flow cytometry was established to delineate the cellular landscape of murine lungs under steady-state and cancer conditions. Fluorochromes were used multiple times to be able to measure 24 cell surface markers with only 13 detectors, yielding a broad picture for whole-lung phenotyping. Primary and metastatic murine lung tumor models were included to detect major cell populations in the lung, and to identify alterations to the distribution patterns in these models. In the primary tumor models, major altered populations included CD324(+) epithelial cells, alveolar macrophages, dendritic cells, and blood and lymph endothelial cells. The number of fibroblasts, vascular smooth muscle cells, monocytes (Ly6C(+) and Ly6C(-)) and neutrophils were elevated in metastatic models of lung cancer. Thus, the proposed clustering approach is a promising method to resolve cell populations from complex organs in detail even with basic flow cytometers
Co-delivery of carbonic anhydrase IX inhibitor and doxorubicin as a promising approach to address hypoxia-induced chemoresistance
Hypoxia, an oxygen-deprived condition of the tumor, is one of the major reasons for resistance to chemotherapy. Carbonic anhydrases are generally involved in pH homeostasis in normal conditions, but in solid tumors having a strong relation with hypoxia, the carbonic anhydrase IX (CA-IX) enzyme is overexpressed and results in an extracellular acidic environment. For most weakly basic anticancer drugs, including doxorubicin (Dox), the ionization in an acidic environment limits their cellular uptake, and consequently, the tumor exposure to the drug at sub-therapeutic concentration comes out as chemoresistance. Herein, a combined drug delivery system of liposomes and mesoporous silica nanoparticles (MSNPs) was developed for the co-delivery of the CA-IX enzyme inhibitor and Dox in hypoxic condition. The unique structure of MSNPs with higher surface area was utilized for higher drug loading and sustained release of Dox. Additionally, the biocompatible nature of liposomal coating as a second loading site for the CA-IX enzyme inhibitor has provided gatekeeping effects at pore opening to avoid premature drug release. Lipid coated MSNPs as a co-delivery system for Dox and the CA-IX inhibitor have synergistic cytotoxic effects against MDA-MB 231 breast cancer cells in hypoxic conditions. These findings assure the potential of this drug delivery system to overcome hypoxia-related chemoresistance
S1PR4 ablation reduces tumor growth and improves chemotherapy via CD8(+) T cell expansion
Observing electronic structures on ex-situ grown topological insulator thin films
Topological insulators represent a new state of quantum matter recently discovered with insulating bulk but conducting surface states formed by an odd number of Dirac fermions. In this Letter, we report our recent progress on the study of electronic structures of ex-situ grown topological insulator thin films by angle resolved photoemission spectroscopy (ARPES). We successfully obtained the topological band structures of molecular beam epitaxial HgTe and vapor-solid grown Bi2Te3 thin films after proper surface cleaning procedures. This new development will not only enable us to study more topological insulators that cannot be measured by conventional in-situ ARPES technique (e. g. by cleaving or growing samples in-situ), but also open the door to directly characterize the electronic properties of topological insulators used in functional devices. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimMaterials Science, MultidisciplinaryPhysics, AppliedPhysics, Condensed MatterSCI(E)EI7ARTICLE1-2,SI130-132
Circular photogalvanic effect in HgTe/CdHgTe quantum well structures
We describe the observation of the circular and linear photogalvanic effects in HgTe/CdHgTe quantum wells. The interband absorption of mid-infrared radiation as well as the intrasubband absorption of terahertz radiation in the quantun well structures is shown to cause a dc electric current due to these effects. The photocurrent magnitude and direction varies with the radiation polarization state and crystallographic orientation of the substrate in a simple way that can be understood from a phenomenological theory. The observed dependences of the photocurrent on the radiation wavelength and temperature are discussed in terms of a microscopic model