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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6

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Department: search.filters.department.Department of Molecular Biology and GeneticsSubject: search.filters.subject.Optics

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    PublicationOpen Access
    Low-signal limit of X-ray single particle diffractive imaging
    (Optical Society of America (OSA), 2019) Ayyer, Kartik; Morgan, Andrew J.; Aquila, Andrew; Hogue, Brenda G.; Kirian, Richard A.; Xavier, P. Lourdu; Yoon, Chun Hong; Chapman, Henry N.; Barty, Anton; Department of Molecular Biology and Genetics; Demirci, Hasan; Faculty Member; Department of Molecular Biology and Genetics; College of Sciences; 307350
    An outstanding question in X-ray single particle imaging experiments has been the feasibility of imaging sub 10-nm-sized biomolecules under realistic experimental conditions where very few photons are expected to be measured in a single snapshot and instrument background may be significant relative to particle scattering. While analyses of simulated data have shown that the determination of an average image should be feasible using Bayesian methods such as the EMC algorithm, this has yet to be demonstrated using experimental data containing realistic non-isotropic instrument background, sample variability and other experimental factors. In this work, we show that the orientation and phase retrieval steps work at photon counts diluted to the signal levels one expects from smaller molecules or with weaker pulses, using data from experimental measurements of 60-nm PR772 viruses. Even when the signal is reduced to a fraction as little as 1/256, the virus electron density determined using ab initio phasing is of almost the same quality as the high-signal data. However, we are still limited by the total number of patterns collected, which may soon be mitigated by the advent of high repetition-rate sources like the European XFEL and LCLS-II.
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    PublicationOpen Access
    Bidirectional optical neuromodulation using capacitive charge-transfer
    (The Optical Society (OSA) Publishing, 2020) Department of Electrical and Electronics Engineering; N/A; Department of Chemical and Biological Engineering; Department of Molecular Biology and Genetics; Melikov, Rustamzhon; Srivastava, Shashi Bhushan; Karatüm, Onuralp; Nizamoğlu, Sedat; Doğru-Yüksel, Itır Bakış; Dikbaş, Uğur Meriç; Kavaklı, İbrahim Halil; PhD Student; Researcher; PhD Student; Faculty Member; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Department of Molecular Biology and Genetics; Graduate School of Sciences and Engineering; College of Engineering; College of Sciences; N/A; N/A; N/A; 130295; N/A; N/A; 40319
    Artificial control of neural activity allows for understanding complex neural networks and improving therapy of neurological disorders. Here, we demonstrate that utilization of photovoltaic biointerfaces combined with light waveform shaping can generate safe capacitive currents for bidirectional modulation of neurons. The differential photoresponse of the biointerface due to double layer capacitance facilitates the direction control of capacitive currents depending on the slope of light intensity. Moreover, the strength of capacitive currents is controlled by changing the rise and fall time slope of light intensity. This approach allows for high-level control of the hyperpolarization and depolarization of membrane potential at single-cell level. Our results pave the way toward advanced bioelectronic functionalities for wireless and safe control of neural activity.