Helmholtz-Zentrum Berlin für Materialien und Energie

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    Automated quantification of vacuole fusion and lipophagy in Saccharomyces cerevisiae from fluorescence and cryo soft X ray microscopy data using deep learning

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    During starvation in the yeast Saccharomyces cerevisiae vacuolar vesicles fuse and lipid droplets LDs can become internalized into the vacuole in an autophagic process named lipophagy. There is a lack of tools to quantitatively assess starvation induced vacuole fusion and lipophagy in intact cells with high resolution and throughput. Here, we combine soft X ray tomography SXT with fluorescence microscopy and use a deep learning computational approach to visualize and quantify these processes in yeast. We focus on yeast homologs of mammalian NPC1 NPC intracellular cholesterol transporter 1; Ncr1 in yeast and NPC2 proteins, whose dysfunction leads to Niemann Pick type C NPC disease in humans. We developed a convolutional neural network CNN model which classifies fully fused versus partially fused vacuoles based on fluorescence images of stained cells. This CNN, named Deep Yeast Fusion Network DYFNet , revealed that cells lacking Ncr1 ncr1 amp; 8710; cells or Npc2 npc2 amp; 8710; cells have a reduced capacity for vacuole fusion. Using a second CNN model, we implemented a pipeline named LipoSeg to perform automated instance segmentation of LDs and vacuoles from high resolution reconstructions of X ray tomograms. From that, we obtained 3D renderings of LDs inside and outside of the vacuole in a fully automated manner and additionally measured droplet volume, number, and distribution. We find that ncr1 amp; 8710; and npc2 amp; 8710; cells could ingest LDs into vacuoles normally but showed compromised degradation of LDs and accumulation of lipid vesicles inside vacuoles. Our new method is versatile and allows for analysis of vacuole fusion, droplet size and lipophagy in intact cell

    Field induced magnetic transitions in the highly anisotropic ferrimagnet ErFe5Al7 studied by high field x ray magnetic dichroism

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    We present a comprehensive study of the magnetic properties of the strongly anisotropic ferrimagnet ErFe5Al7 in pulsed magnetic fields up to 30 T applied along the hard magnetization axis within the basal plane of the tetragonal lattice around the compensation temperature Tcomp . Macroscopic measurements showed two anomalies at about 8 T and 25 T in a small temperature range around Tcomp. High field x ray magnetic circular dichroism XMCD data at the Er M5 and the Fe L3 edge resonances provide insight into the element selective magnetization processes, revealing a coherent rotation of Er 4f and Fe 3d moments, with stepwise jumps including an unexpected one from an easy to a hard magnetization axis. XMCD at the Er L3 edge resonance elucidates the role of Er 5d electrons in coupling the Er 4f and the Fe 3d moments. Finally, an in plane anisotropy constant was evaluated from a simulation of the magnetization process at temperatures well below Tcomp using a two sublattice mode

    In vitro assessment of internal implant abutment connections with different cone angles under static loading using synchrotron based radiation

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    Background The stability of implant abutment connection is crucial to minimize mechanical and biological complications. Therefore, an assessment of the microgap behavior and abutment displacement in different implant abutment designs was performed. Methods Four implant systems were tested, three with a conical implant abutment connection based on friction fit and a cone angle amp; 8201; lt; amp; 8201;12 Medentika, Medentis, NobelActive and a system with an angulated connection lt; amp; 8201;40 Semados . In different static loading conditions 30 N amp; 8201; amp; 8722; amp; 8201;90 , 100 N amp; 8201; amp; 8722; amp; 8201;90 , 200 N amp; 8201; amp; 8722; amp; 8201;30 the microgap and abutment displacement was evaluated using synchrotron based microtomography and phase contrast radioscopy with numerical forward simulation of the optical Fresnel propagation yielding an accuracy down to 0.1 amp; 956;m. Results Microgaps were present in all implant systems prior to loading 0.15 9 amp; 956;m . Values increased with mounting force and angle up to 40.5 amp; 956;m at an off axis loading of 100 N in a 90 angle. Conclusions In contrast to the implant abutment connection with a large cone angle 45 , the conical connections based on a friction fit small cone angles with lt; amp; 8201;12 demonstrated an abutment displacement which resulted in a deformation of the outer implant wall. The design of the implant abutment connection seems to be crucial for the force distribution on the implant wall which might influence peri implant bone stabilit

    How Atomic Bonding Plays the Hardness Behavior in the Al Co Cr Cu Fe Ni High Entropy Family

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    A systematic study on a face centered cubic based compositionally complex alloy system Al Co Cr Cu Fe Ni in its single phase state is carried out, where a mother senary compound Al8Co17Cr17Cu8Fe17Ni33 and five of its suballoys, obtained by removing one element at a time, are investigated and exhaustively analyzed determining the contribution of each alloying element in the solid solution. The senary and the quinaries are compared using experimental techniques including X ray absorption spectroscopy, X ray diffraction, transmission electron microscopy, and first principles hybrid Monte Carlo molecular dynamics simulations. Chemical short range order and bond length distances have been determined both at the experimental and computational level. Electronic structure and local atomic distortions up to 5.2 amp; 8201; have been correlated to the microhardness values. A linear regression model connecting hardness with local lattice distortions is presente

    Solution driven processing of calcium sulfate The mechanism of the reversible transformation of gypsum to bassanite in brines

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    Here, we show that calcium sulfate dihydrate gypsum can be directly, rapidly and reversibly converted to calcium sulfate hemihydrate bassanite in high salinity solutions brines . The optimum conditions for the efficient production of bassanite in a short time lt;5 min involve the use of brines with c NaCl gt; 4 M and maintaining a temperature, T gt; 80 C. When the solution containing bassanite crystals is cooled down to around room temperature, eventually gypsum is formed. When the temperature is raised again to T gt; 80 C, bassanite is rapidly re precipitated. This contrasts with the better known behaviour of the bassanite phase in low salt environments. In low salinity aqueous solutions, bassanite is considered to be metastable with respect to gypsum and anhydrite, and therefore gypsum to bassanite conversion does not occur in pure water. Interestingly, the high salinity transformation of gypsum to bassanite has been reported by many authors and used in practice for several decades, although its very occurrence actually contradicts numerical thermodynamic predictions regarding solubility of calcium sulfate phases. By following the evolution of crystalline phases with in situ and time resolved X ray diffraction scattering and Raman spectroscopy, we demonstrated that the phase stability in brines at elevated temperatures was inaccurately represented in the thermodynamic databases. Most notably for c NaCl gt; 4 M, and T gt; 80 C gypsum becomes readily more soluble than bassanite, which induces the direct precipitation of the latter from gypsum. The fact that these transformations are controlled by the solution provides extensive opportunities for precise manipulation of crystal formation. Our experiments confirmed that bassanite remained the sole crystalline phase for many hours before reverting into gypsum. This property is extremely advantageous for practical processing and efficient crystal extraction in industrial scenario

    Improved Air Stability of Tin Halide Perovskite Solar Cells by an N Type Active Moisture Barrier

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    Tin halide perovskite solar cells are promising for the next generation of highly efficient photovoltaics. Their commercialization can be accelerated by increasing their stability in moisture and oxygen. Herein, an n type organic molecule IO 4Cl is applied as an interlayer between the perovskite films and electron transport layers in p i n structured devices. The electron rich indacenodithieno [3,2 b]thiophene enhances electron transport, while the hydrocarbon side chains and rigid conjugated backbone isolate air. It is also shown that the C amp; 9552;O in IO 4Cl can coordinate with Sn2 on perovskite films surface and grain boundaries to enhance perovskite crystal stability. In addition, IO 4Cl slows down crystallization dynamics, resulting in lower non radiation recombination. The moisture ingress in the perovskite films is tracked under high relative humidity RH and it is found that IO 4Cl can mitigate moisture infiltration. Finally, the devices with IO 4Cl maintain 95 of the initial power conversion efficiency after 1200 h of storage in a nitrogen filled glovebox, and their stability in ambient air 60 80 RH is significantly improved against pristine devices, thus demonstrating the beneficial effects of IO 4Cl interlayer on device stabilit

    Interfacial Passivation Engineering for Highly Efficient Quantum Dot Light Emitting Diodes via Aromatic Amine Functionalized Dipole Molecules

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    Blue quantum dot QD light emitting diodes QLEDs exhibit unsatisfactory operational stability and electroluminescence EL properties due to severe nonradiative recombination induced by large numbers of dangling bond defects and charge imbalance in QD. Herein, dipolar aromatic amine functionalized molecules with different molecular polarities are employed to regulate charge transport and passivate interfacial defects between QD and the electron transfer layer ETL . The results show that the stronger the molecular polarity, especially with the amp; 8722;CF3 groups possessing a strong electron withdrawing capacity, the more effective the defect passivation of S and Zn dangling bonds at the QD surface. Moreover, the dipole interlayer can effectively reduce electron injection into QD at high current density, enhancing charge balance and mitigating Joule heat. Finally, blue QLEDs exhibit a peak external quantum efficiency EQE of 21.02 with an operational lifetime T50 at 100 cd m 2 exceeding 4000

    Poly 3 hexylthiophene perovskite Heterointerface by Spinodal Decomposition Enabling Efficient and Stable Perovskite Solar Cells

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    The best research cell efficiency of perovskite solar cells PSCs is comparable with that of mature silicon solar cells SSCs ; However, the industrial development of PSCs lags far behind SSCs. PSC is a multiphase and multicomponent system, whose consequent interfacial energy loss and carrier loss seriously affect the performance and stability of devices. Here, by using spinodal decomposition, a spontaneous solid phase segregation process, in situ introduces a poly 3 hexylthiophene perovskite P3HT PVK heterointerface with interpenetrating structure in PSCs. The P3HT PVK heterointerface tunes the energy alignment, thereby reducing the energy loss at the interface; The P3HT PVK interpenetrating structure bridges a transport channel, thus decreasing the carrier loss at the interface. The simultaneous mitigation of energy and carrier losses by P3HT PVK heterointerface enables n i p geometry device a power conversion efficiency of 24.53 certified 23.94 and excellent stability. These findings demonstrate an ingenious strategy to optimize the performance of PSCs by heterointerface via Spinodal decompositio

    Near surface electronic structure in strained Ni ferrite films An x ray absorption spectroscopy study

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    We report on the x ray absorption spectra XAS and x ray magnetic circular dichroism XMCD of a series of NiFe2O4 Ni ferrite films grown on symmetry matched substrates and measured in two geometries out of plane and near in plane. The Ni ferrite films, grown by pulsed laser deposition, are epitaxial and the substrates used ZnGa2O4, CoGa2O4, MgGa2O4, and MgAl2O4 introduce a systematic variation in the lattice mismatch between the substrate and the film. Modeling of the XAS and XMCD spectra, both measured with the surface sensitive total electron yield mode, indicates that the Ni2 cations reside on the octahedrally coordinated lattice sites in the spinel structure. Analyses of the Fe XAS and XMCD spectra are consistent with Fe3 cations occupying a subset of the octahedral and tetrahedral sites in the spinel oxide lattice with the addition of a small amount of Fe2 located on octahedral sites. The Ni2 orbital to spin moment ratio mu l mu s , derived from the application of XMCD sum rules, is enhanced for the substrates with a small lattice mismatch relative to NiFe2O4. The results suggest a path for increasing the orbital moment in NiFe2O4 by applying thin film growth techniques that can maintain a highly strained lattice for the NiFe2O4 fil

    Electrodeposition of copper on niobium for cryocooler application

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    The electrodeposition of copper onto niobium using commercial acidic and alkaline electrolytes was tested. The continuous dense polycrystalline copper films were successfully obtained in aqueous alkaline type bath containing copper sulphate, sodium hydroxide and sodium gluconate. The effect of benzotriazole and sodium lauryl sulphate additives on the morphology and crystal structure of the deposited copper was investigated by optical and scanning electron microscopy, and X ray diffraction. No copper oxides were found in the grown films. Copper films had moderate adhesion properties that would be insufficient for cryocooler application. We are currently exploring different compositions of electrolyte baths for obtaining the coatings on niobium with improved adhesio

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