83 research outputs found

    Scalable and Transfer-Free Fabrication of MoS2/SiO2 Hybrid Nanophotonic Cavity Arrays with Quality Factors Exceeding 4000

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    We report the fully-scalable fabrication of a large array of hybrid molybdenum disulfide (MoS2) -silicon dioxide (SiO2) one-dimensional, free-standing photonic-crystal cavities capable of enhancement of the MoS2 photoluminescence at the narrow cavity resonance. We demonstrate continuous tunability of the cavity resonance wavelength across the entire emission band of MoS2 simply by variation of the photonic crystal periodicity. Device fabrication started by substrate-scale growth of MoS2 using chemical vapor deposition (CVD) on non-birefringent thermal oxide on a silicon wafer;it was followed by lithographic fabrication of a photonic crystal nanocavity array on the same substrate at more than 50% yield of functional devices. Our cavities exhibit three dominant modes with measured linewidths less than 0.2 nm, corresponding to quality factors exceeding 4000. All experimental findings are found to be in excellent agreement with finite difference time domain (FDTD) simulations. CVD MoS2 provides scalable access to a direct band gap, inorganic, stable and efficient emitter material for onchip photonics without the need for epitaxy and is at CMOS compatible processing parameters even for back-end-of-line integration;our findings suggest feasibility of cavity based line-narrowing in MoS2-based on-chip devices as it is required for instance for frequency-multiplexed operation in on-chip optical communication and sensing

    Position determination of resident space objects via triangulation with two passive-optical staring systems

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    The number of space objects orbiting the Earth is rapidly increasing. An opportunity to detect and measure the position of space objects are passive optical staring systems, e.g. our system called APPARILLO. While staring systems are capable of measuring highly accurate equatorial coordinates of space objects via an astrometric calibration, they do not provide information on their altitude unless the space object is assumed to fly on a circular orbit. In this work we discuss an approach in which the altitude of a space object is measured via triangulation (simultaneous observation with two staring systems placed at different positions on Earth). Based on theoretical calculations, we estimate that the triangulation with two staring systems can provide the altitude of a typical space object in a low Earth orbit with an accuracy as low as 200 m. This is two orders of magnitude better compared to a simple circular orbit approximation that can be used for a single staring system

    Recovery of the PHA Copolymer P(HB-co-HHx) With Non-halogenated Solvents: Influences on Molecular Weight and HHx-Content

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    Biodegradable and biocompatible polyhydroxyalkanoates (PHAs) are promising alternatives to conventional plastics. Based on the chain length of their monomers they are classified as short chain length (scl-) or medium chain length (mcl-) PHA polymers. The type of monomers, the composition and the molecular weight (MW) define the polymer properties. To accelerate the use of PHA as a bulk material, the downstream associated costs need to be minimized. This study focuses on the evaluation of non-halogenated solvents, especially acetone as a scl-PHA non-solvent, for the recovery of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) – P(HB-co-HHx) – with an mcl-HHx content >15 mol% and a MW average (Mw) < 2 × 105 Da. Solvents and precipitants were chosen regarding zeotrope formation, boiling point differences, and toxicity. Non-halogenated solvent-precipitant pairs were evaluated regarding the MW characteristics (MWCs) of the extracted polymer. Acetone and 2-propanol as a low toxic and zeotropic solvent-precipitant pair was evaluated at different extraction temperatures and multiple extraction times. The extraction process was further evaluated by using impure acetone for the extraction and implementing a multi-stage extraction process. Additionally, P(HB-co-HHx) extracted with three different solvents was characterized by 1H and 13C-APT NMR. The screening of precipitants resulted in a negative influence on the MWCs by ethanol precipitation for extractions with acetone and ethyl acetate, respectively. It was observed, that extractions with acetone at 70°C extracted a higher fraction of PHA from the cells compared to extractions at RT, but the Mw was decreased by 9% in average. Acetone with a 2-propanol fraction of up to 30% was still able to extract the polymer 95% as efficient as pure acetone. Additionally, when acetone and ethyl acetate were used in a multi-stage extraction process, a two-stage process was sufficient to extract 98–99% of the polymer from the cells. 1H and 13C-APT NMR analysis confirmed the monomer fraction and structure of the extracted polymers and revealed a random copolymer structure. The presented strategy can be further developed to an ecological and economically feasible PHA downstream process and thus contributes to the commercialization of low-cost PHAs.TU Berlin, Open-Access-Mittel – 2020BMBF, 031B0001C, Bioökonomie International 2014: PHABIO APP - Polyhydroxyalkanoate Biopolymere aus tierischen Abfallfetten fĂŒr die Produktion von wertschöpfendem, biobasierten und abbauendem Plastik; Teilprojekt CBMBF, 031B0001B, Bioökonomie International 2014: PHABIO APP - Polyhydroxyalkanoate Biopolymere aus tierischen Abfallfetten fĂŒr die Produktion von wertschöpfendem, biobasierten und abbauendem Plastik; Teilprojekt BBMBF, 031B0798C, Bioökonomie International 2017: PHABio-up - Polyhydroxyalkanoate Biopolymere aus tierischen Abfallfetten: Scale-up zur Realisierung einer industriellen Produktion - Teilvorhaben: Feedstock und Produktextraktio

    Health-Related Quality of Life and Mental Health after Surgical Treatment of Hepatocellular Carcinoma in the Era of Minimal-Invasive Surgery: Resection versus Transplantation

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    Laparoscopic liver resection (LLR) is an increasingly relevant treatment option for patients with resectable hepatocellular carcinoma (HCC). Orthotopic liver transplantation (OLT) has been considered optimal treatment for HCC in cirrhosis, but is challenged by rising organ scarcity. While health-related quality of life (HRQoL) and mental health are well-documented after OLT, little is known about HRQoL in HCC patients after LLR. We identified all HCC patients who underwent LLR at our hospital between 2014 and 2018. HRQoL and mental health were assessed using the Short Form 36 and the Hospital Anxiety and Depression Scale, respectively. Outcomes were compared to a historic cohort of HCC patients after OLT. Ninety-eight patients received LLR for HCC. Postoperative morbidity was 25% with 17% minor complications. LLR patients showed similar overall HRQoL and mental health to OLT recipients, except for lower General Health (p = 0.029) and higher anxiety scores (p = 0.010). We conclude that LLR can be safely performed in patients with HCC, with or without liver cirrhosis. The postoperative HRQoL and mental health are comparable to that of OLT recipients in most aspects. LLR should thus always be considered an alternative to OLT, especially in times of organ shortage

    Ascites’ neutrophil function is significantly impaired in patients with decompensated cirrhosis but can be restored by autologous plasma incubation

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    Systemic immune cell dysfunction is a typical feature of liver diseases and increases the risk of bacterial infection, especially spontaneous bacterial peritonitis. We evaluated functional properties of neutrophil granulocytes in blood and ascites of patients both with and without decompensated cirrhosis. We collected blood and ascites samples from 63 patients with cirrhosis and eight without cirrhosis. Phagocytosis activity (PA) and oxidative burst activity (OBA) were evaluated after ex vivo stimulation with E. coli, while fluorescence signals were measured by flow cytometry. Ascites’ neutrophil function tests were repeated after incubation with autologous plasma. Ascites’ neutrophils showed an impaired PA and OBA (median blood PA 98.1% (86.8–99.8) vs. ascites’ PA 50.5% (0.4–97.3), p < 0.0001; median blood OBA 98.7% (27.5–100) vs. ascites’ OBA 27.5% (0.3–96.7), p < 0.0001). Patients with non- cirrhotic ascites showed higher PA but equally suppressed OBA. Ascites’ neutrophil function could be partially restored after incubation with autologous plasma (median increase PA: 22.5% (−49.7 – +93.2), p = 0.002; OBA: 22.8% (−10.4 – +48.8), p = 0.002). Ascites’ neutrophils of patients with cirrhosis are functionally impaired, but could be partially restored after incubation with plasma. Further investigations are needed to identify the factors in ascites that are associated with neutrophils’ function

    TIE2-expressing monocytes and M2-polarized macrophages impact survival and correlate with angiogenesis in adenocarcinoma of the pancreas

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    Introduction: M2-polarized tumor-associated macrophages (TAMs) and TIE2- expressing monocytes (TEMs) are associated with angiogenesis and have been identified as a potential prognostic marker in several solid tumors, including hepatobiliary malignancies. However, little is known regarding their influence on tumor progression and patient survival in pancreatic ductal adenocarcinoma (PDAC). Results: Patients with tumors characterized by the presence of CD163+ TAMs or TEMs in TCA or TIF, respectively, showed a significantly decreased 1-, 3- and 5-year overall and recurrence-free survival compared to patients without CD163+ TAMs or TEMs (all ρ < 0.05). Patients with TEMs in TCA showed a higher incidence of tumor recurrence (ρ < 0.05). Furthermore, the presence of CD163+ TAMs was associated with a higher tumor MVD (ρ < 0.05). Conclusions: Presence of M2-polarized TAMs and TEMs is associated with a decreased overall and recurrence-free survival of patients with PDAC. Materials and methods: The localization and density of CD163+ M2-polarized TAMs and TEMs were quantified in the tumor central area (TCA) and tumor-infiltrating front (TIF) in human PDAC tissue (n = 106) and correlated to clinicopathological characteristics, tumor recurrence rates and patient survival. In parallel, tumor microvascular density (MVD) and the density of angiopoietin-positive tumor cells were quantified. Statistical analysis was performed using SPSS software

    Lasertechnik fĂŒr das Verkehrsmanagement im All: Technologien fĂŒr eine nachhaltige Raumfahrt

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    Die stark zunehmende Anzahl an Satelliten ermöglicht großen Fortschritt in der Wissenschaft und Technik und eröffnet neue Möglichkeiten wie ein weltweit verfĂŒgbares Internet. Gleichzeitig sind damit Herausforderungen fĂŒr das Verkehrsmanagement im Weltraum (meist Englisch als Space Traffic Management bezeichnet) verbunden. Simulationen zeigen, dass die Anzahl an Kollisionswarnungen im niedrigen Erdorbit allein durch den Ausbau von 5 Megakonstellationen (Starlink, OneWeb, Amazon Kuiper, Guo Wang und SatRevolution) mit insgesamt ca. 70000 Satelliten etwa um den Faktor 4000 ansteigen wird. Durch weitere Satelliten und zusĂ€tzlichen WeltraummĂŒll wird diese Zunahme real weitaus grĂ¶ĂŸer sein. Selbst wenn sich Kollisionen durch Ausweichmanöver verhindern lassen, verursachen diese hohe Kosten. Um die Anzahl an notwendigen Ausweichmanövern zu reduzieren und die weiterhin notwendigen Manöver effizient zu machen, ist eine hochprĂ€zise Vermessung der Bahndaten der Weltraumobjekte erforderlich. Je genauer die Bahndaten sind, desto kleiner ist der Abstand in dem die Weltraumobjekte bei gleichem Kollisionsrisiko aneinander vorbeifliegen können. Beim Satellitenlaserranging (SLR) wird die Laufzeit eines gepulsten Lasers vermessen, der von einer Bodenstation emittiert und durch einen am Satelliten befestigten Retroreflektor wieder antiparallel zu dieser zurĂŒck reflektiert wird. Dadurch lassen sich millimetergenaue AbstĂ€nde ermitteln, aus denen die Bahndaten des Satelliten errechnet werden. Da diese Messungen viel prĂ€zisiere Daten liefern als derzeit verfĂŒgbar, wĂŒrden ca. 99% aller Ausweichmanöver unnötig werden. In Zusammenarbeit mit der Industrie entwickeln wir eine kompakte und transportable SLR Bodenstation, das miniSLRÂź. Hiermit konnte kĂŒrzlich gezeigt werden, dass trotz der kompakten, kostengĂŒnstigen Bauweise und der Nutzung von, gegenĂŒber anderen SLR Stationen, verhĂ€ltnismĂ€ĂŸig langen Laserpulse durch Datenmittelung Millimeter prĂ€zise Abstandsmessungen erzielt werden. Um den Nutzen der SLR Technologie fĂŒr das Space Traffic Management weiter zu erhöhen, arbeiten wir weiterhin an der Entwicklung von polarimetrischem SLR. Dies soll neben der Bahnvermessung auch eine Identifikation von Satelliten (z.B. nach Massenstarts von Kleinsatelliten) ermöglichen. HierfĂŒr werden spezielle Retroreflektoren entwickelt, welche fĂŒr die Raumfahrt qualifiziert und in zukĂŒnftigen Missionen getestet werden sollen

    The value of hepatic resection in metastasic renal cancer in the era of Tyrosinkinase Inhibitor Therapy

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    Background: The value of liver-directed therapy (LDT) in patients with metastasic renal cell carcinoma (MRCC) is still an active field of research, particularly in the era of tyrosinkinase inhibitor (TKI) therapy. Methods: The records of 35 patients with MRCC undergoing LDT of metastasic liver lesions between 1992 and 2015 were retrospectively analyzed. Immediate postoperative TKI was given in a subgroup of patients after LDT for metastasic lesions. Uni- and multivariate models were applied to assess overall survival (OS), progression-free survival (PFS) and disease-free survival (DFS). Results: Following primary tumor (renal cell cancer) resection and LDT, respectively, median OS was better for a total of 16 patients (41 %) receiving immediate postoperative TKI with 151 and 98 months, when compared to patients without TKI therapy with 61 (p = 0.003) and 40 months (p = 0.032). Immediate postoperative TKI was associated with better median PFS (47 months versus 19 months; p = 0.023), whereas in DFS only a trend was observed (51 months versus 19 months; p = 0.110). Conclusions: LDT should be considered as a suitable additive tool in the era of TKI therapy of MRCC to the liver. In this context, postoperative TKI therapy seems to be associated with better OS and PFS, but not DFS

    Investigating human audio-visual object perception with a combination of hypothesis-generating and hypothesis-testing fMRI analysis tools

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    Primate multisensory object perception involves distributed brain regions. To investigate the network character of these regions of the human brain, we applied data-driven group spatial independent component analysis (ICA) to a functional magnetic resonance imaging (fMRI) data set acquired during a passive audio-visual (AV) experiment with common object stimuli. We labeled three group-level independent component (IC) maps as auditory (A), visual (V), and AV, based on their spatial layouts and activation time courses. The overlap between these IC maps served as definition of a distributed network of multisensory candidate regions including superior temporal, ventral occipito-temporal, posterior parietal and prefrontal regions. During an independent second fMRI experiment, we explicitly tested their involvement in AV integration. Activations in nine out of these twelve regions met the max-criterion (A &lt; AV &gt; V) for multisensory integration. Comparison of this approach with a general linear model-based region-of-interest definition revealed its complementary value for multisensory neuroimaging. In conclusion, we estimated functional networks of uni- and multisensory functional connectivity from one dataset and validated their functional roles in an independent dataset. These findings demonstrate the particular value of ICA for multisensory neuroimaging research and using independent datasets to test hypotheses generated from a data-driven analysis
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