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Mar 2019 • The Journal of infectious diseases

Highly sensitive and specific Zika virus serological assays using a magnetic modulation biosensing system

Yehudit Michelson, Yaniv Lustig, Shira Avivi, Eli Schwartz, Amos Danielli

BackgroundZika virus has created global alarm because it has been associated with catastrophic fetal abnormalities, including microcephaly, spontaneous abortion, and intrauterine growth restriction. Current serological assays that detect antiviral antibodies suffer from low sensitivity and high cross-reactivity among different flaviviruses.MethodsIn this study, utilizing a novel magnetic modulation biosensing (MMB) system and the Zika nonstructural 1 protein, we show highly sensitive and specific Zika serological assays. We blindly tested 60 reverse-transcription polymerase chain reaction Zika-positive samples and healthy patients’ serum samples, as well as 44 serum samples from enzyme-linked immunosorbent assay (ELISA) West Nile- and dengue-positive patients. The Zika-positive samples were collected from Israeli travelers returning from Zika-endemic areas …

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Mar 2019 • Chemistry Letters

Trimodal nanoparticle contrast agent for ct, mri and spect imaging: Synthesis and characterization of radiolabeled core/shell iron oxide@ gold nanoparticles

Menachem Motiei, Tamar Dreifuss, Tamar Sadan, Noam Omer, Tamar Blumenfeld-Katzir, Eirini Fragogeorgi, George Loudos, Rachela Popovtzer, Noam Ben-Eliezer

Recently, nanoparticles have emerged as promising contrast agents for various imaging applications. In this paper, we present the synthesis and characterization of a novel hybrid nano-structure, consisting of an iron oxide@gold nanoparticle, labeled with technetium-99m, for trimodal SPECT/CT/MRI imaging. The particles showed efficient capabilities as CT/MRI imaging agent and high radiochemical yield, indicating a potential single hybrid material for multimodal SPECT/CT/MRI.

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Mar 2019 • JOSA B

Difference frequency generation of ultraviolet from X-ray pulses in opaque materials

Eviatar Minerbi, S Shwartz

We suggest a new approach for observing x-ray nonlinear wave mixing in opaque materials. We focus on difference frequency generation of ultraviolet radiation from two short x-ray pulses by measuring the depletion of the pumping pulses. Like other processes involving nonlinear interactions between x-rays and longer wavelengths, our method can lead to the development of a probe for spectroscopy of valence electrons at the atomic scale resolution. The two main advantages of the method we propose over the direct observation of the generated signal are the ability to probe the properties of materials at wavelengths where they are opaque and the higher predicted efficiency in the ultraviolet regime. We describe a possible experimental setup with realistic specifications optimized with respect to the characteristics of the input pulses. We expect that experimental observations of the effect will be feasible with the …

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Mar 2019 • Particle & Particle Systems Characterization

Morphological, Structural, and Compositional Evolution of Pt–Ni Octahedral Electrocatalysts with Pt‐Rich Edges and Ni‐Rich Core: Toward the Rational Design of Electrocatalysts …

Meital Shviro, Martin Gocyla, Shlomi Polani, Marc Heggen, David Zitoun, Rafal E Dunin‐Borkowski

The progress in colloidal synthesis of Pt–Ni octahedra has been instrumental in rising the oxygen reduction reaction catalytic activity high above the benchmark of Pt catalysts. This impressive catalytic performance is believed to result from the exposure of the most active catalytic sites after an activation process, chemical or electrochemical, which leads to a Pt surface enrichment. A foremost importance is to understand the structure and the elemental distribution of Pt–Ni octahedral, which leads to an optimal catalytic activity and stability. However, the factors governing the synthesis of the Pt–Ni octahedra are not well understood. In this study, unprecedented surface atomic segregation of Pt atoms in a Ni‐rich Pt–Ni octahedral nanoparticle structure is established by advanced electron microscopy. The Pt atoms are almost exclusively located on the edges of the Pt–Ni octahedra. This structure is formed in a pristine …

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Mar 2019 • Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XVI …, 2019

An optical method to detect tissue scattering: theory, experiments and biomedical applications

I Yariv, H Duadi, D Fixler

In vivo physiological sensing is typically done either by imaging thin tissues or by examining changes in the attenuation coefficient. One known technique for thin tissue in vivo applications is the optical coherence tomography (OCT). However, deep tissue methods are usually based on diffusion reflection (DR), which correlates the optical properties to the reflected light intensity. The attenuation coefficient is composed of tissue absorption and scattering. We present a noninvasive nanophotonics technique, the iterative multi-plane optical property extraction (IMOPE) for extracting the scattering properties from a turbid medium. The reflectance-based IMOPE is most relevant for in vivo applications, hence, in this research we suggest a new theoretical description of phase accumulation in deep tissue, which is rarely mentioned in the literature, using a modified DR theory that represents the phase based on the effective …

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Mar 2019 • Carbon

Imidazole decorated reduced graphene oxide: A biomimetic ligand for selective oxygen reduction electrocatalysis with Metalloporphyrins

Rifael Z Snitkoff, Naomi Levy, Inbal Ozery, Sharon Ruthstein, Lior Elbaz

We propose herein a bio-mimetic catalytic structure as a new approach to increase the oxygen reduction catalytic selectivity of transition metal complexes. As in biological systems, where there is a series of mediators between the active site and the surface, that lowers the activation energy of the overall reaction and increases its selectivity, we use here a structure where a molecular catalyst Fe(III)tetrakis(1-methyl-4-pyridyl) porphyrin is bonded to a surface via a benzimidazole mediator. Using electron paramagnetic resonance (EPR), UV–vis spectroscopy and electrochemical measurements, we compared the ORR activity of the molecular catalyst with and without benzimidazole and show that this ligand strongly influences the selectivity of the reaction and shifts it from the 2 to the 2+2-electron reduction.

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Mar 2019 • ChemCatChem

Ultrafine ruthenium oxide nanoparticles supported on molybdenum oxide nanosheets as highly efficient electrocatalyst for hydrogen evolution in acidic medium

Hari Krishna Sadhanala, Villa Krishna Harika, Tirupathi Rao Penki, Doron Aurbach, Aharon Gedanken

Notably, compared to MoO3 or RuO2, the composite exhibited high exchange current density of 0.57 mAcmÀ 2, and a current density of 10 mAcmÀ 2 was achieved at low overpotential of 110mV in 0.5 MH2so4. The Tafel slope of the MoO3@ RuO2 catalyst was 62 mVdecÀ 1 and it showed excellent stability. This remarkable performance can be attributed to the synergetic effect generated by the strong interaction between MoO3 nanosheets and RuO2 nanoparticles, which resulted in enhanced long-term stability as well.

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Mar 2019 • Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XVI …, 2019

Insulin-coated gold nanoparticles as an effective approach for bypassing the blood-brain barrier

Oshra Betzer, Malka Shilo, Menachem Motiei, Rachela Popovtzer

A major challenge for treatment of neurodegenerative disorders is the need to overcome the restrictive mechanism of the blood-brain-barrier (BBB) for delivery of therapeutic agents into the brain. Our goal was to develop an efficient nanoparticle-based system with the ability to bypass the BBB by targeting insulin receptors. We demonstrate that insulincoated gold-nanoparticles (INS-GNPs) can serve as an effective endogenous BBB transport system for delivering therapeutics into the brain. We further conducted a quantitative in-vivo investigation of the effect of nanoparticle size (20, 50 and 70nm) on the ability of INS-GNPs to cross the BBB. The most widespread bio-distribution and highest accumulation within the brain (5% of the injected dose) was observed using 20nm INS-GNPs, two hours post-injection. In-vivo CT imaging revealed that particles migrated to specific brain regions, rich in insulin receptors, which …

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Feb 2019 • Optics express

X-ray computational ghost imaging with single-pixel detector

Y Klein, A Schori, IP Dolbnya, K Sawhney, S Shwartz

We demonstrate computational ghost imaging at X-ray wavelengths with only one single-pixel detector. We show that, by using a known designed mask as a diffuser that induces intensity fluctuations in the probe beam, it is possible to compute the propagation of the electromagnetic field in the absence of the investigated object. We correlate these calculations with the measured data when the object is present in order to reconstruct the images of 50 μm and 80 μm slits. Our results open the possibilities for X-ray high-resolution imaging with partially coherent X-ray sources and can lead to a powerful tool for X-ray three-dimensional imaging.

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Feb 2019 • Langmuir

Microfluidic Devices Containing ZnO Nanorods with Tunable Surface Chemistry and Wetting-Independent Water Mobility

Mirit Hen, Eitan Edri, Ortal Guy, Dorit Avrahami, Hagay Shpaisman, Doron Gerber, Chaim N Sukenik

Interest in polydimethylsiloxane (PDMS) microfluidic devices has grown dramatically in recent years, particularly in the context of improved performance lab-on-a-chip devices with decreasing channel size enabling more devices on ever smaller chips. As channels become smaller, the resistance to flow increases and the device structure must be able to withstand higher internal pressures. We report herein the fabrication of microstructured surfaces that promote water mobility independent of surface static wetting properties. The key tool in this approach is the growth of ZnO nanorods on the bottom face of the microfluidic device. We show that water flow in these devices is similar whether the textured nanorod-bearing surface is hydrophilic or superhydrophobic; that is, the device tolerates a wide range of surface wetting properties without changing the water flow within the device. This is not the case for smooth …

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Feb 2019 • Developmental biology

Gonadal supporting cells acquire sex-specific chromatin landscapes during mammalian sex determination

S Alexandra Garcia-Moreno, Christopher R Futtner, Isabella M Salamone, Nitzan Gonen, Robin Lovell-Badge, Danielle M Maatouk

Cis-regulatory elements are critical for the precise spatiotemporal regulation of genes during development. However, identifying functional regulatory sites that drive cell differentiation in vivo has been complicated by the high numbers of cells required for whole-genome epigenetic assays. Here, we identified putative regulatory elements during sex determination by performing ATAC-seq and ChIP-seq for H3K27ac in purified XX and XY gonadal supporting cells before and after sex determination in mice. We show that XX and XY supporting cells initiate sex determination with similar chromatin landscapes and acquire sex-specific regulatory elements as they commit to the male or female fate. To validate our approach, we identified a functional gonad-specific enhancer downstream of Bmp2, an ovary-promoting gene. This work increases our understanding of the complex regulatory network underlying mammalian …

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Feb 2019 • Physical Review B

Infinite-randomness fixed point of the quantum superconductor-metal transitions in amorphous thin films

Nicholas A Lewellyn, Ilana M Percher, JJ Nelson, Javier Garcia-Barriocanal, Irina Volotsenko, Aviad Frydman, Thomas Vojta, Allen M Goldman

The magnetic-field-tuned quantum superconductor-insulator transitions of disordered amorphous indium oxide films are a paradigm in the study of quantum phase transitions and exhibit power-law scaling behavior. For superconducting indium oxide films with low disorder, such as the ones reported on here, the high-field state appears to be a quantum-corrected metal. Resistance data across the superconductor-metal transition in these films are shown here to obey an activated scaling form appropriate to a quantum phase transition controlled by an infinite-randomness fixed point in the universality class of the random transverse-field Ising model. Collapse of the field-dependent resistance vs temperature data is obtained using an activated scaling form appropriate to this universality class, using values determined through a modified form of power-law scaling analysis. This exotic behavior of films exhibiting a …

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Feb 2019 • Nano Letters

Golden exosomes selectively target brain pathologies in neurodegenerative and neurodevelopmental disorders

Nisim Perets, Oshra Betzer, Ronit Shapira, Shmuel Brenstein, Ariel Angel, Tamar Sadan, Uri Ashery, Rachela Popovtzer, Daniel Offen

Exosomes, nanovesicles that are secreted by different cell types, enable intercellular communication at local or distant sites. Alhough they have been found to cross the blood brain barrier, their migration and homing abilities within the brain remain unstudied. We have recently developed a method for longitudinal and quantitative in vivo neuroimaging of exosomes based on the superior visualization abilities of classical X-ray computed tomography (CT), combined with gold nanoparticles as labeling agents. Here, we used this technique to track the migration and homing patterns of intranasally administrated exosomes derived from bone marrow mesenchymal stem cells (MSC-exo) in different brain pathologies, including stroke, autism, Parkinson’s disease, and Alzheimer’s disease. We found that MSC-exo specifically targeted and accumulated in pathologically relevant murine models brains regions up to 96 h post …

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Feb 2019 • Single Molecule Spectroscopy and Superresolution Imaging XII 10884, 1088406, 2019

3D super-resolution imaging using a generalized and scalable progressive refinement method on sparse recovery (PRIS)

Xiyu Yi, Rafael Piestun, Shimon Weiss

Within the family of super-resolution (SR) fluorescence microscopy, single-molecule localization microscopies (PALM[1], STORM[2] and their derivatives) afford among the highest spatial resolution (approximately 5 to 10 nm), but often with moderate temporal resolution. The high spatial resolution relies on the adequate accumulation of precise localizations, which requires a relatively low density of bright fluorophores. Several methods have demonstrated localization at higher densities in both two dimensions (2D)[3, 4] and three dimensions (3D)[5-7]. Additionally, with further advancements, such as functional super-resolution[8, 9] and point spread function (PSF) engineering with[8-11] or without[12] multi-channel observations, extra information (spectra, dipole orientation) can be encoded and recovered at the single molecule level. However, such advancements are not fully extended for high-density conditions in …

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Feb 2019 • Nucleic acids research

The effect of macromolecular crowding on single-round transcription by Escherichia coli RNA polymerase

SangYoon Chung, Eitan Lerner, Yan Jin, Soohong Kim, Yazan Alhadid, Logan Wilson Grimaud, Irina X Zhang, Charles M Knobler, William M Gelbart, Shimon Weiss

Previous works have reported significant effects of macromolecular crowding on the structure and behavior of biomolecules. The crowded intracellular environment, in contrast to in vitro buffer solutions, likely imparts similar effects on biomolecules. The enzyme serving as the gatekeeper for the genome, RNA polymerase (RNAP), is among the most regulated enzymes. Although it was previously demonstrated that macromolecular crowding affects association of RNAP to DNA, not much is known about how crowding acts on late initiation and promoter clearance steps, which are considered to be the rate-determining steps for many promoters. Here, we demonstrate that macromolecular crowding enhances the rate of late initiation and promoter clearance using in vitro quenching-based single-molecule kinetics assays. Moreover, the enhancement’s dependence on crowder size notably deviates from predictions …

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Feb 2019 • Scientific reports

Imaging of nanoparticle dynamics in live and apoptotic cells using temporally-modulated polarization

Omer Wagner, Moty Schultz, Eitan Edri, Rinat Meir, Eran Barnoy, Amihai Meiri, Hagay Shpaisman, Eli Sloutskin, Zeev Zalevsky

Gold nanoparticles are widely exploited in phototherapy. Owing to their biocompatibility and their strong visible-light surface plasmonic resonance, these particles also serve as contrast agents for cell image enhancement and super-resolved imaging. Yet, their optical signal is still insufficiently strong for many important real-life applications. Also, the differentiation between adjacent nanoparticles is usually limited by the optical resolution and the orientations of non-spherical particles are unknown. These limitations hamper the progress in cell research by direct optical microscopy and narrow the range of phototherapy applications. Here we demonstrate exploiting the optical anisotropy of non-spherical nanoparticles to achieve super-resolution in live cell imaging and to resolve the intracellular nanoparticle orientations. In particular, by modulating the light polarization and taking advantage of the polarization …

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Feb 2019 • Nano letters

Excitation and emission transition dipoles of type-II semiconductor nanorods

Subhabrata Ghosh, Anna M Chizhik, Gaoling Yang, Narain Karedla, Ingo Gregor, Dan Oron, Shimon Weiss, Jörg Enderlein, Alexey I Chizhik

The mechanisms of exciton generation and recombination in semiconductor nanocrystals are crucial to the understanding of their photophysics and for their application in nearly all fields. While many studies have been focused on type-I heterojunction nanocrystals, the photophysics of type-II nanorods, where the hole is located in the core and the electron is located in the shell of the nanorod, remain largely unexplored. In this work, by scanning single nanorods through the focal spot of radially and azimuthally polarized laser beams and by comparing the measured excitation patterns with a theoretical model, we determine the dimensionality of the excitation transition dipole of single type-II nanorods. Additionally, by recording defocused patterns of the emission of the same particles, we measure their emission transition dipoles. The combination of these techniques allows us to unambiguously deduce the …

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Feb 2019 • ECS Meeting Abstracts

(Keynote) Updates in Non-Aqueous Mg Electrochemistry, Biu Corner.

Doron Aurbach

Developing practical rechargeable magnesium batteries (RMB) is very attractive. The first rechargeable magnesium battery prototype was demonstrated almost two decade ago. It comprised magnesium metal anode, Mo6S8 Chevrel phase cathode, and complex ethereal solutions that included THF or glymes and ionic organo-metallic species formed by complicated reactions between a RnMgCl2-n Lewis base and an AlClnR3-n Lewis acid (R = alkyl or aryl groups). These prototypes exhibited very prolonged cycle life at 100% cycling efficiency (no side reactions). However the low abundance of molybdenum and the low energy density (1.1V, 120mAh/g cathode capacity) avoided any practical development of these first systems. Unfortunately, we are not aware of any practically promising RMB that that could show better electrochemical performance that the 19 years old first prototype. A main challenge related to …

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Feb 2019 • Journal of The Electrochemical Society

The Ratio between the Surface Charge and Electrode's Capacitance as a Fast Tool for Assessing the Charge Efficiency in Capacitive Deionization Processes

Ayelet Kalfa, Izaak Cohen, Eran Avraham, Doron Aurbach

This paper suggests an effective approach to evaluate carbon electrodes that can be effective in capacitive de-ionization processes of salty aqueous solutions. The first assessment of any electrode material, before its assembly in a CDI cell, includes its specific capacitance and its electric conductivity among other physical properties. These properties may bring a sense whether the electrode can be suitable for electro-adsorption processes, but can hardly tell about the efficiency of the process which is related to the charge utilization. A new term is discussed-the ratio between the specific capacity of an electrode and the specific charge related to the electrode's surface groups. A close inspection of the amphoteric modified Donnan model of the electric double layer shows that the ratio between the surface charge density and the integral specific capacitance, namely, the overall charge density, of the carbon electrodes …

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Feb 2019 • Optics Express

Interaction-free ghost-imaging of structured objects

Yingwen Zhang, Alicia Sit, Frédéric Bouchard, Hugo Larocque, Florence Grenapin, Eliahu Cohen, Avshalom C Elitzur, James L Harden, Robert W Boyd, Ebrahim Karimi

Quantum – or classically correlated – light can be employed in various ways to improve resolution and measurement sensitivity. In an “interaction-free” measurement, a single photon can be used to reveal the presence of an object placed within one arm of an interferometer without being absorbed by it. With a technique known as “ghost-imaging”, entangled photon pairs are used for detecting an opaque object with significantly improved signal-to-noise ratio while preventing over-illumination. Here, we integrate these two methods to obtain a new imaging technique which we term “interaction-free ghost-imaging” (IFGI). With this new technique, we reduce photon illumination on the object by up to 26.5% while still maintaining at least the same image quality of conventional ghost-imaging. Alternatively, IFGI can improve image signal-to-noise ratio by 18% when given the same number of interacting photons as in …

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Feb 2019 • Biophysical Journal

Cusp Artifacts in High Order Superresolution Optical Fluctuation Imaging (SOFI)

Xiyu Yi, Shimon Weiss

Since its introduction, Super-resolution Optical Fluctuation Imaging (SOFI) has attracted interest due to its simplicity and affordability. Many applications, methodology enhancements, and derivative methods have since been introduced. One of the most important and attractive features of SOFI is its high order cumulant image reconstruction, which could potentially yield unlimited resolution enhancement.Practical application of high order (higher than 4) SOFI has been, however, limited. The reasons for such limitation have never been fully understood (nor fully discussed). In this work, careful analysis of the artifacts of high order SOFI cumulants is provided. We have identified that there is a portion of highly non-intuitive artifacts (dubbed here as ‘cusp’artifacts) hidden in the high order SOFI cumulants, which have been overlooked in previous studies. A series of realistic simulations were performed to study cusp …

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