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Now showing 1 - 10 of 26
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    A tale of shifting relations: East Asian summer and winter monsoon variability during the Holocene
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Kaboth-Bahr, Stefanie; Bahr, André; Zeeden, Christian; Yamoah, Kweku A.; Lone, Mahjoor Ahmad; Chuang, Chih-Kai; Löwemark, Ludvig; Wei, Kuo-Yen
    Understanding the dynamics between the East Asian summer (EASM) and winter monsoon (EAWM) is needed to predict their variability under future global warming scenarios. Here, we investigate the relationship between EASM and EAWM as well as the mechanisms driving their variability during the last 10,000 years by stacking marine and terrestrial (non-speleothem) proxy records from the East Asian realm. This provides a regional and proxy independent signal for both monsoonal systems. The respective signal was subsequently analysed using a linear regression model. We find that the phase relationship between EASM and EAWM is not time-constant and significantly depends on orbital configuration changes. In addition, changes in the Atlantic Meridional Overturning circulation, Arctic sea-ice coverage, El Niño-Southern Oscillation and Sun Spot numbers contributed to millennial scale changes in the EASM and EAWM during the Holocene. We also argue that the bulk signal of monsoonal activity captured by the stacked non-speleothem proxy records supports the previously argued bias of speleothem climatic archives to moisture source changes and/or seasonality.
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    Stable coherent mode-locking based on π pulse formation in single-section lasers
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Arkhipov, Rostislav; Pakhomov, Anton; Arkhipov, Mikhail; Babushkin, Ihar; Rosanov, Nikolay
    Here we consider coherent mode-locking (CML) regimes in single-section cavity lasers, taking place for pulse durations less than atomic population and phase relaxation times, which arise due to coherent Rabi oscillations of the atomic inversion. Typically, CML is introduced for lasers with two sections, the gain and absorber ones. Here we show that, for certain combination of the cavity length and relaxation parameters, a very stable CML in a laser, containing only gain section, may arise. The mode-locking is unconditionally self-starting and appears due to balance of intra-pulse de-excitation and slow interpulse-scale pump-induced relaxation processes. We also discuss the scaling of the system to shorter pulse durations, showing a possibility of mode-locking for few-cycle pulses.
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    Particle movements provoke avalanche-like compaction in soft colloid filter cakes
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Lüken, Arne; Stüwe, Lucas; Lohaus, Johannes; Linkhorst, John; Wessling, Matthias
    During soft matter filtration, colloids accumulate in a compressible porous cake layer on top of the membrane surface. The void size between the colloids predominantly defines the cake-specific permeation resistance and the corresponding filtration efficiency. While higher fluxes are beneficial for the process efficiency, they compress the cake and increase permeation resistance. However, it is not fully understood how soft particles behave during cake formation and how their compression influences the overall cake properties. This study visualizes the formation and compression process of soft filter cakes in microfluidic model systems. During cake formation, we analyze single-particle movements inside the filter cake voids and how they interact with the whole filter cake morphology. During cake compression, we visualize reversible and irreversible compression and distinguish the two phenomena. Finally, we confirm the compression phenomena by modeling the soft particle filter cake using a CFD-DEM approach. The results underline the importance of considering the compression history when describing the filter cake morphology and its related properties. Thus, this study links single colloid movements and filter cake compression to the overall cake behavior and narrows the gap between single colloid events and the filtration process.
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    Author Correction: Influence of plasma treatment on SiO2/Si and Si3N4/Si substrates for large-scale transfer of graphene
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Lukose, R.; Lisker, M.; Akhtar, F.; Fraschke, M.; Grabolla, T.; Mai, A.; Lukosius, M.
    The original version of this Article omitted an affiliation for M. Lisker. The correct affiliations for M. Lisker are listed below: IHP- Leibniz Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236, Frankfurt (Oder), Germany Technical University of Applied Science Wildau, Hochschulring 1, 15745, Wildau, Germany The original Article and accompanying Supplementary Information file have been corrected.
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    Modified wavelet analysis of ECoG-pattern as promising tool for detection of the blood–brain barrier leakage
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Runnova, Anastasiya; Zhuravlev, Maksim; Ukolov, Rodion; Blokhina, Inna; Dubrovski, Alexander; Lezhnev, Nikita; Sitnikova, Evgeniya; Saranceva, Elena; Kiselev, Anton; Karavaev, Anatoly; Selskii, Anton; Semyachkina-Glushkovskaya, Oxana; Penzel, Thomas; Kurths, Jurgen
    A new approach for detection oscillatory patterns and estimation of their dynamics based by a modified CWT skeleton method is presented. The method opens up additional perspectives for the analysis of subtle changes in the oscillatory activity of complex nonstationary signals. The method was applied to analyze unique experimental signals obtained in usual conditions and after the non-invasive increase in the blood–brain barrier (BBB) permeability in 10 male Wistar rats. The results of the wavelet-analysis of electrocorticography (ECoG) recorded in a normal physiological state and after an increase in the BBB permeability of animals demonstrate significant changes between these states during wakefulness of animals and an essential smoothing of these differences during sleep. Sleep is closely related to the processes of observed changes in the BBB permeability.
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    Skin tolerant inactivation of multiresistant pathogens using far-UVC LEDs
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Glaab, Johannes; Lobo-Ploch, Neysha; Cho, Hyun Kyong; Filler, Thomas; Gundlach, Heiko; Guttmann, Martin; Hagedorn, Sylvia; Lohan, Silke B.; Mehnke, Frank; Schleusener, Johannes; Sicher, Claudia; Sulmoni, Luca; Wernicke, Tim; Wittenbecher, Lucas; Woggon, Ulrike; Zwicker, Paula; Kramer, Axel; Meinke, Martina C.; Kneissl, Michael; Weyers, Markus; Winterwerber, Ulrike; Einfeldt, Sven
    Multiresistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) cause serious postoperative infections. A skin tolerant far-UVC (< 240 nm) irradiation system for their inactivation is presented here. It uses UVC LEDs in combination with a spectral filter and provides a peak wavelength of 233 nm, with a full width at half maximum of 12 nm, and an irradiance of 44 µW/cm2. MRSA bacteria in different concentrations on blood agar plates were inactivated with irradiation doses in the range of 15–40 mJ/cm2. Porcine skin irradiated with a dose of 40 mJ/cm2 at 233 nm showed only 3.7% CPD and 2.3% 6-4PP DNA damage. Corresponding irradiation at 254 nm caused 11–14 times higher damage. Thus, the skin damage caused by the disinfectant doses is so small that it can be expected to be compensated by the skin's natural repair mechanisms. LED-based far-UVC lamps could therefore soon be used in everyday clinical practice to eradicate multiresistant pathogens directly on humans.
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    Templating the morphology of soft microgel assemblies using a nanolithographic 3D-printed membrane
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Linkhorst, John; Lölsberg, Jonas; Thill, Sebastian; Lohaus, Johannes; Lüken, Arne; Naegele, Gerhard; Wessling, Matthias
    Filter cake formation is the predominant phenomenon limiting the filtration performance of membrane separation processes. However, the filter cake’s behavior at the particle scale, which determines its overall cake behavior, has only recently come into the focus of scientists, leaving open questions about its formation and filtration behavior. The present study contributes to the fundamental understanding of soft filter cakes by analyzing the influence of the porous membrane’s morphology on crystal formation and the compaction behavior of soft filter cakes under filtration conditions. Microfluidic chips with nanolithographic imprinted filter templates were used to trigger the formation of crystalline colloidal filter cakes formed by soft microgels. The soft filter cakes were observed via confocal laser scanning microscopy (CLSM) under dead-end filtration conditions. Colloidal crystal formation in the cake, as well as their compaction behavior, were analyzed by optical visualization and pressure data. For the first time, we show that exposing the soft cake to a crystalline filter template promotes the formation of colloidal crystallites and that soft cakes experience gradient compression during filtration.
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    Dislocations in ceramic electrolytes for solid-state Li batteries
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Porz, L.; Knez, D.; Scherer, M.; Ganschow, S.; Kothleitner, G.; Rettenwander, D.
    High power solid-state Li batteries (SSLB) are hindered by the formation of dendrite-like structures at high current rates. Hence, new design principles are needed to overcome this limitation. By introducing dislocations, we aim to tailor mechanical properties in order to withstand the mechanical stress leading to Li penetration and resulting in a short circuit by a crack-opening mechanism. Such defect engineering, furthermore, appears to enable whisker-like Li metal electrodes for high-rate Li plating. To reach these goals, the challenge of introducing dislocations into ceramic electrolytes needs to be addressed which requires to establish fundamental understanding of the mechanics of dislocations in the particular ceramics. Here we evaluate uniaxial deformation at elevated temperatures as one possible approach to introduce dislocations. By using hot-pressed pellets and single crystals grown by Czochralski method of Li6.4La3Zr1.4Ta0.6O12 garnets as a model system the plastic deformation by more than 10% is demonstrated. While conclusions on the predominating deformation mechanism remain challenging, analysis of activation energy, activation volume, diffusion creep, and the defect structure potentially point to a deformation mechanism involving dislocations. These parameters allow identification of a process window and are a key step on the road of making dislocations available as a design element for SSLB.
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    Deep learning-based classification of blue light cystoscopy imaging during transurethral resection of bladder tumors
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Ali, Nairveen; Bolenz, Christian; Todenhöfer, Tilman; Stenzel, Arnulf; Deetmar, Peer; Kriegmair, Martin; Knoll, Thomas; Porubsky, Stefan; Hartmann, Arndt; Popp, Jürgen; Kriegmair, Maximilian C.; Bocklitz, Thomas
    Bladder cancer is one of the top 10 frequently occurring cancers and leads to most cancer deaths worldwide. Recently, blue light (BL) cystoscopy-based photodynamic diagnosis was introduced as a unique technology to enhance the detection of bladder cancer, particularly for the detection of flat and small lesions. Here, we aim to demonstrate a BL image-based artificial intelligence (AI) diagnostic platform using 216 BL images, that were acquired in four different urological departments and pathologically identified with respect to cancer malignancy, invasiveness, and grading. Thereafter, four pre-trained convolution neural networks were utilized to predict image malignancy, invasiveness, and grading. The results indicated that the classification sensitivity and specificity of malignant lesions are 95.77% and 87.84%, while the mean sensitivity and mean specificity of tumor invasiveness are 88% and 96.56%, respectively. This small multicenter clinical study clearly shows the potential of AI based classification of BL images allowing for better treatment decisions and potentially higher detection rates.
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    Direct measurement of Coulomb-laser coupling
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2021) Azoury, Doron; Krüger, Michael; Bruner, Barry D.; Smirnova, Olga; Dudovich, Nirit
    The Coulomb interaction between a photoelectron and its parent ion plays an important role in a large range of light-matter interactions. In this paper we obtain a direct insight into the Coulomb interaction and resolve, for the first time, the phase accumulated by the laser-driven electron as it interacts with the Coulomb potential. Applying extreme-ultraviolet interferometry enables us to resolve this phase with attosecond precision over a large energy range. Our findings identify a strong laser-Coulomb coupling, going beyond the standard recollision picture within the strong-field framework. Transformation of the results to the time domain reveals Coulomb-induced delays of the electrons along their trajectories, which vary by tens of attoseconds with the laser field intensity.