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  1. AU=Assalauova Dameli
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  1. Article: Classification of diffraction patterns using a convolutional neural network in single-particle-imaging experiments performed at X-ray free-electron lasers.

    Assalauova, Dameli / Ignatenko, Alexandr / Isensee, Fabian / Trofimova, Darya / Vartanyants, Ivan A

    Journal of applied crystallography

    2022  Volume 55, Issue Pt 3, Page(s) 444–454

    Abstract: Single particle imaging (SPI) at X-ray free-electron lasers is particularly well suited to determining the 3D structure of particles at room temperature. For a successful reconstruction, diffraction patterns originating from a single hit must be isolated ...

    Abstract Single particle imaging (SPI) at X-ray free-electron lasers is particularly well suited to determining the 3D structure of particles at room temperature. For a successful reconstruction, diffraction patterns originating from a single hit must be isolated from a large number of acquired patterns. It is proposed that this task could be formulated as an image-classification problem and solved using convolutional neural network (CNN) architectures. Two CNN configurations are developed: one that maximizes the F1 score and one that emphasizes high recall. The CNNs are also combined with expectation-maximization (EM) selection as well as size filtering. It is observed that the CNN selections have lower contrast in power spectral density functions relative to the EM selection used in previous work. However, the reconstruction of the CNN-based selections gives similar results. Introducing CNNs into SPI experiments allows the reconstruction pipeline to be streamlined, enables researchers to classify patterns on the fly, and, as a consequence, enables them to tightly control the duration of their experiments. Incorporating non-standard artificial-intelligence-based solutions into an existing SPI analysis workflow may be beneficial for the future development of SPI experiments.
    Language English
    Publishing date 2022-04-22
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2020879-0
    ISSN 1600-5767 ; 0021-8898
    ISSN (online) 1600-5767
    ISSN 0021-8898
    DOI 10.1107/S1600576722002667
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Mitigating the photodegradation of all-inorganic mixed-halide perovskite nanocrystals by ligand exchange.

    Wahl, Jan / Haizmann, Philipp / Kirsch, Christopher / Frecot, Rene / Mukharamova, Nastasia / Assalauova, Dameli / Kim, Young Yong / Zaluzhnyy, Ivan / Chassé, Thomas / Vartanyants, Ivan A / Peisert, Heiko / Scheele, Marcus

    Physical chemistry chemical physics : PCCP

    2022  Volume 24, Issue 18, Page(s) 10944–10951

    Abstract: We show that the decomposition of caesium lead halide perovskite nanocrystals under continuous X-ray illumination depends on the surface ligand. For oleic acid/oleylamine, we observe a fast decay accompanied by the formation of elemental lead and halogen. ...

    Abstract We show that the decomposition of caesium lead halide perovskite nanocrystals under continuous X-ray illumination depends on the surface ligand. For oleic acid/oleylamine, we observe a fast decay accompanied by the formation of elemental lead and halogen. Upon surface functionalization with a metal porphyrin derivative, the decay is markedly slower and involves the disproportionation of lead to Pb
    Language English
    Publishing date 2022-05-11
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d2cp00546h
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: In situ

    Lapkin, Dmitry / Mukharamova, Nastasia / Assalauova, Dameli / Dubinina, Svetlana / Stellhorn, Jens / Westermeier, Fabian / Lazarev, Sergey / Sprung, Michael / Karg, Matthias / Vartanyants, Ivan A / Meijer, Janne-Mieke

    Soft matter

    2022  Volume 18, Issue 8, Page(s) 1591–1602

    Abstract: Depending on the volume fraction and interparticle interactions, colloidal suspensions can form different phases, ranging from fluids, crystals, and glasses to gels. For soft microgels that are made from thermoresponsive polymers, the volume fraction can ...

    Abstract Depending on the volume fraction and interparticle interactions, colloidal suspensions can form different phases, ranging from fluids, crystals, and glasses to gels. For soft microgels that are made from thermoresponsive polymers, the volume fraction can be tuned by temperature, making them excellent systems to experimentally study phase transitions in dense colloidal suspensions. However, investigations of phase transitions at high particle concentration and across the volume phase transition temperature in particular, are challenging due to the deformability and possibility for interpenetration between microgels. Here, we investigate the dense phases of composite core-shell microgels that have a small gold core and a thermoresponsive microgel shell. Employing Ultra Small-Angle X-ray Scattering, we make use of the strong scattering signal from the gold cores with respect to the almost negligible signal from the shells. By changing the temperature we study the freezing and melting transitions of the system
    Language English
    Publishing date 2022-02-23
    Publishing country England
    Document type Journal Article
    ZDB-ID 2191476-X
    ISSN 1744-6848 ; 1744-683X
    ISSN (online) 1744-6848
    ISSN 1744-683X
    DOI 10.1039/d1sm01537k
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Book ; Online: Revealing the impact of polystyrene-functionalization of Au octahedral nanocrystals of different sizes on formation and structure of mesocrystals

    Lapkin, Dmitry / Singh, Shweta / Kirner, Felizitas / Sturm, Sebastian / Assalauova, Dameli / Ignatenko, Alexandr / Wiek, Thomas / Gemming, Thomas / Lubk, Axel / Müller-Caspary, Knut / Khadiev, Azat / Novikov, Dmitri / Sturm, Elena V. / Vartanyants, Ivan A.

    2023  

    Abstract: The self-assembly of anisotropic nanocrystals (stabilized by organic capping molecules) with pre-selected composition, size, and shape allows for the creation of nanostructured materials with unique structures and features. For such a material, the shape ...

    Abstract The self-assembly of anisotropic nanocrystals (stabilized by organic capping molecules) with pre-selected composition, size, and shape allows for the creation of nanostructured materials with unique structures and features. For such a material, the shape and packing of the individual nanoparticles play an important role. This work presents a synthesis procedure for {\omega}-thiol-terminated polystyrene (PS-SH) functionalized gold nanooctahedra of variable size (edge length 37, 46, 58, and 72 nm). The impact of polymer chain length (Mw: 11k, 22k, 43k, and 66k g/mol) on the growth of colloidal crystals (e.g. mesocrystals) and their resulting crystal structure is investigated. Small-angle X-ray scattering (SAXS) and scanning transmission electron microscopy (STEM) methods provide a detailed structural examination of the self-assembled faceted mesocrystals based on octahedral gold nanoparticles of different size and surface functionalization. Three-dimensional angular X-ray cross-correlation analysis (AXCCA) enables high-precision determination of the superlattice structure and relative orientation of nanoparticles in mesocrystals. This approach allows us to perform non-destructive characterization of mesocrystalline materials and reveals their structure with resolution down to the nanometer scale.

    Comment: 46 pages, 5 figures, 12 Supplementary Information figures, 1 Table in the main text, 1 Table in Supplementary Information
    Keywords Condensed Matter - Materials Science ; Condensed Matter - Mesoscale and Nanoscale Physics
    Subject code 540
    Publishing date 2023-06-26
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Spatially resolved fluorescence of caesium lead halide perovskite supercrystals reveals quasi-atomic behavior of nanocrystals.

    Lapkin, Dmitry / Kirsch, Christopher / Hiller, Jonas / Andrienko, Denis / Assalauova, Dameli / Braun, Kai / Carnis, Jerome / Kim, Young Yong / Mandal, Mukunda / Maier, Andre / Meixner, Alfred J / Mukharamova, Nastasia / Scheele, Marcus / Schreiber, Frank / Sprung, Michael / Wahl, Jan / Westendorf, Sophia / Zaluzhnyy, Ivan A / Vartanyants, Ivan A

    Nature communications

    2022  Volume 13, Issue 1, Page(s) 892

    Abstract: We correlate spatially resolved fluorescence (-lifetime) measurements with X-ray nanodiffraction to reveal surface defects in supercrystals of self-assembled cesium lead halide perovskite nanocrystals and study their effect on the fluorescence properties. ...

    Abstract We correlate spatially resolved fluorescence (-lifetime) measurements with X-ray nanodiffraction to reveal surface defects in supercrystals of self-assembled cesium lead halide perovskite nanocrystals and study their effect on the fluorescence properties. Upon comparison with density functional modeling, we show that a loss in structural coherence, an increasing atomic misalignment between adjacent nanocrystals, and growing compressive strain near the surface of the supercrystal are responsible for the observed fluorescence blueshift and decreased fluorescence lifetimes. Such surface defect-related optical properties extend the frequently assumed analogy between atoms and nanocrystals as so-called quasi-atoms. Our results emphasize the importance of minimizing strain during the self-assembly of perovskite nanocrystals into supercrystals for lighting application such as superfluorescent emitters.
    Language English
    Publishing date 2022-02-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-022-28486-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Observation of a single protein by ultrafast X-ray diffraction.

    Ekeberg, Tomas / Assalauova, Dameli / Bielecki, Johan / Boll, Rebecca / Daurer, Benedikt J / Eichacker, Lutz A / Franken, Linda E / Galli, Davide E / Gelisio, Luca / Gumprecht, Lars / Gunn, Laura H / Hajdu, Janos / Hartmann, Robert / Hasse, Dirk / Ignatenko, Alexandr / Koliyadu, Jayanath / Kulyk, Olena / Kurta, Ruslan / Kuster, Markus /
    Lugmayr, Wolfgang / Lübke, Jannik / Mancuso, Adrian P / Mazza, Tommaso / Nettelblad, Carl / Ovcharenko, Yevheniy / Rivas, Daniel E / Rose, Max / Samanta, Amit K / Schmidt, Philipp / Sobolev, Egor / Timneanu, Nicusor / Usenko, Sergey / Westphal, Daniel / Wollweber, Tamme / Worbs, Lena / Xavier, Paul Lourdu / Yousef, Hazem / Ayyer, Kartik / Chapman, Henry N / Sellberg, Jonas A / Seuring, Carolin / Vartanyants, Ivan A / Küpper, Jochen / Meyer, Michael / Maia, Filipe R N C

    Light, science & applications

    2024  Volume 13, Issue 1, Page(s) 15

    Abstract: The idea of using ultrashort X-ray pulses to obtain images of single proteins frozen in time has fascinated and inspired many. It was one of the arguments for building X-ray free-electron lasers. According to theory, the extremely intense pulses provide ... ...

    Abstract The idea of using ultrashort X-ray pulses to obtain images of single proteins frozen in time has fascinated and inspired many. It was one of the arguments for building X-ray free-electron lasers. According to theory, the extremely intense pulses provide sufficient signal to dispense with using crystals as an amplifier, and the ultrashort pulse duration permits capturing the diffraction data before the sample inevitably explodes. This was first demonstrated on biological samples a decade ago on the giant mimivirus. Since then, a large collaboration has been pushing the limit of the smallest sample that can be imaged. The ability to capture snapshots on the timescale of atomic vibrations, while keeping the sample at room temperature, may allow probing the entire conformational phase space of macromolecules. Here we show the first observation of an X-ray diffraction pattern from a single protein, that of Escherichia coli GroEL which at 14 nm in diameter is the smallest biological sample ever imaged by X-rays, and demonstrate that the concept of diffraction before destruction extends to single proteins. From the pattern, it is possible to determine the approximate orientation of the protein. Our experiment demonstrates the feasibility of ultrafast imaging of single proteins, opening the way to single-molecule time-resolved studies on the femtosecond timescale.
    Language English
    Publishing date 2024-01-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 2662628-7
    ISSN 2047-7538 ; 2047-7538
    ISSN (online) 2047-7538
    ISSN 2047-7538
    DOI 10.1038/s41377-023-01352-7
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  7. Book ; Online: Classification of diffraction patterns in single particle imaging experiments performed at X-ray free-electron lasers using a convolutional neural network

    Ignatenko, Alexandr / Assalauova, Dameli / Bobkov, Sergey A. / Gelisio, Luca / Teslyuk, Anton B. / Ilyin, Viacheslav A. / Vartanyants, Ivan A.

    2020  

    Abstract: Single particle imaging (SPI) is a promising method for native structure determination which has undergone a fast progress with the development of X-ray Free-Electron Lasers. Large amounts of data are collected during SPI experiments, driving the need ... ...

    Abstract Single particle imaging (SPI) is a promising method for native structure determination which has undergone a fast progress with the development of X-ray Free-Electron Lasers. Large amounts of data are collected during SPI experiments, driving the need for automated data analysis. The necessary data analysis pipeline has a number of steps including binary object classification (single versus multiple hits). Classification and object detection are areas where deep neural networks currently outperform other approaches. In this work, we use the fast object detector networks YOLOv2 and YOLOv3. By exploiting transfer learning, a moderate amount of data is sufficient for training of the neural network. We demonstrate here that a convolutional neural network (CNN) can be successfully used to classify data from SPI experiments. We compare the results of classification for the two different networks, with different depth and architecture, by applying them to the same SPI data with different data representation. The best results are obtained for YOLOv2 color images linear scale classification, which shows an accuracy of about 97% with the precision and recall of about 52% and 61%, respectively, which is in comparison to manual data classification.

    Comment: 23 pages, 6 figures, 3 tables
    Keywords Electrical Engineering and Systems Science - Image and Video Processing ; Physics - Computational Physics ; Physics - Data Analysis ; Statistics and Probability
    Subject code 006
    Publishing date 2020-08-17
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article: Erratum: An advanced workflow for single-particle imaging with the limited data at an X-ray free-electron laser. Corrigendum.

    Assalauova, Dameli / Kim, Young Yong / Bobkov, Sergey / Khubbutdinov, Ruslan / Rose, Max / Alvarez, Roberto / Andreasson, Jakob / Balaur, Eugeniu / Contreras, Alice / DeMirci, Hasan / Gelisio, Luca / Hajdu, Janos / Hunter, Mark S / Kurta, Ruslan P / Li, Haoyuan / McFadden, Matthew / Nazari, Reza / Schwander, Peter / Teslyuk, Anton /
    Walter, Peter / Xavier, P Lourdu / Yoon, Chun Hong / Zaare, Sahba / Ilyin, Viacheslav A / Kirian, Richard A / Hogue, Brenda G / Aquila, Andrew / Vartanyants, Ivan A

    IUCrJ

    2022  Volume 9, Issue Pt 2, Page(s) 328

    Abstract: This corrects the article DOI: 10.1107/S2052252520012798.]. ...

    Abstract [This corrects the article DOI: 10.1107/S2052252520012798.].
    Language English
    Publishing date 2022-03-01
    Publishing country England
    Document type Published Erratum
    ZDB-ID 2754953-7
    ISSN 2052-2525
    ISSN 2052-2525
    DOI 10.1107/S2052252522000501
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Book ; Online: In-situ Characterization of Crystallization and Melting of Soft, Thermoresponsive Microgels by Small-Angle X-ray Scattering

    Lapkin, Dmitry / Mukharamova, Nastasia / Assalauova, Dameli / Dubinina, Svetlana / Stellhorn, Jens / Westermeier, Fabian / Lazarev, Sergey / Sprung, Michael / Karg, Matthias / Vartanyants, Ivan A. / Meijer, Janne-Mieke

    2021  

    Abstract: Depending on the volume fraction and interparticle interactions, colloidal suspensions can form different phases, ranging from fluids, crystals, and glasses to gels. For soft microgels that are made from thermoresponsive polymers, the volume fraction can ...

    Abstract Depending on the volume fraction and interparticle interactions, colloidal suspensions can form different phases, ranging from fluids, crystals, and glasses to gels. For soft microgels that are made from thermoresponsive polymers, the volume fraction can be tuned by temperature, making them excellent systems to experimentally study phase transitions in dense colloidal suspensions. However, investigations of phase transitions at high particle concentration and across the volume phase transition temperature in particular, are challenging due to the deformability and possibility for interpenetration between microgels. Here, we investigate the dense phases of composite core-shell microgels that have a small gold core and a thermoresponsive microgel shell. Employing Ultra Small Angle X-ray Scattering, we make use of the strong scattering signal from the gold cores with respect to the almost negligible signal from the shells. By changing the temperature we study the freezing and melting transitions of the system in-situ. Using Bragg peak analysis and the Williamson-Hall method, we characterize the phase transitions in detail. We show that the system crystallizes into an rhcp structure with different degrees of in-plane and out-of-plane stacking disorder that increase upon particle swelling. We further find that the melting process is distinctly different, where the system separates into two different crystal phases with different melting temperatures and interparticle interactions.
    Keywords Condensed Matter - Soft Condensed Matter
    Subject code 612
    Publishing date 2021-10-27
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Structure-Transport Correlation Reveals Anisotropic Charge Transport in Coupled PbS Nanocrystal Superlattices.

    Maier, Andre / Lapkin, Dmitry / Mukharamova, Nastasia / Frech, Philipp / Assalauova, Dameli / Ignatenko, Alexandr / Khubbutdinov, Ruslan / Lazarev, Sergey / Sprung, Michael / Laible, Florian / Löffler, Ronny / Previdi, Nicolas / Bräuer, Annika / Günkel, Thomas / Fleischer, Monika / Schreiber, Frank / Vartanyants, Ivan A / Scheele, Marcus

    Advanced materials (Deerfield Beach, Fla.)

    2020  Volume 32, Issue 36, Page(s) e2002254

    Abstract: The assembly of colloidal semiconductive nanocrystals into highly ordered superlattices predicts novel structure-related properties by design. However, those structure-property relationships, such as charge transport depending on the structure or even ... ...

    Abstract The assembly of colloidal semiconductive nanocrystals into highly ordered superlattices predicts novel structure-related properties by design. However, those structure-property relationships, such as charge transport depending on the structure or even directions of the superlattice, have remained unrevealed so far. Here, electric transport measurements and X-ray nanodiffraction are performed on self-assembled lead sulfide nanocrystal superlattices to investigate direction-dependent charge carrier transport in microscopic domains of these materials. By angular X-ray cross-correlation analysis, the structure and orientation of individual superlattices is determined, which are directly correlated with the electronic properties of the same microdomains. By that, strong evidence for the effect of superlattice crystallinity on the electric conductivity is found. Further, anisotropic charge transport in highly ordered monocrystalline domains is revealed, which is attributed to the dominant effect of shortest interparticle distance. This implies that transport anisotropy should be a general feature of weakly coupled nanocrystal superlattices.
    Language English
    Publishing date 2020-07-28
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1474949-X
    ISSN 1521-4095 ; 0935-9648
    ISSN (online) 1521-4095
    ISSN 0935-9648
    DOI 10.1002/adma.202002254
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