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Aug 2022 • arXiv preprint arXiv:2208.07799v1

Deep subwavelength resonant metaphotonics enabled by high-index topological insulator bismuth telluride

Danveer Singh, Sukanta Nandi, Yafit Fleger, Shnay Cohen Z., Tomer Lewi

In nanophotonics, small mode volumes, high-quality factor (Q) resonances, and large field enhancements without metals, fundamentally scale with the refractive index and are key for many implementations involving light-matter interactions. Topological insulators (TI) are a class of insulating materials that host topologically protected surface states, some of which exhibit extraordinary high permittivity values. Here, we study the optical properties of TI bismuth telluride (Bi2Te3) single crystals. We find that both the bulk and surface states contribute to the extremely large optical constants, with the real part of the refractive index peaking at n~11. Utilizing these ultra-high index values, we demonstrate that Bi2Te3 metasurfaces are capable of squeezing light in deep subwavelength structures, with the fundamental magnetic dipole (MD) resonance confined in unit cell size smaller than {\lambda}/10. We further show that dense ultrathin metasurface arrays can simultaneously provide large magnetic and electric field enhancements arising from the surface metallic states and the high index of the bulk. These findings demonstrate the potential of chalcogenide TI materials as a platform leveraging the unique combination of ultra-high-index dielectric response with surface metallic states for metamaterial design and nanophotonic applications in sensing, non-linear generation, and quantum information.

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Aug 2022 • IEEE Photonics Journal

Measurement of the Second-Order Polarizability of Silver Nanoparticles With Reference-Free Hyper-Rayleigh Scattering for Entangled Photon Pair Interaction

Ariel Ashkenazy, Racheli Ron, Tchiya Zar, Hannah Aharon, Adi Salomon, Dror Fixler, Eliahu Cohen

Two-photon interactions of entangled-photon pairs with metallic nanoparticles (NPs) can be enhanced by localized surface-plasmon resonance. Recently, we have described how the properties of this quantum light-matter interaction can be deduced from classical second-harmonic generation measurements performed using a reference-free hyper-Rayleigh scattering method. Herein, we report the results of such classical-light characterization measurements. We obtain a large hyperpolarizability for the NPs, present the dependence of the hyperpolarizability on the NPs' spectral features, and show a dipolar emission pattern for the second-harmonic signal. Our results can be used to optimize entangled-photon pair interactions with metallic NPs to enable first ever detection of this process. Moreover, these results suggest that NPs may be used as source for ultra-broadband entangled-photon pairs through nonphase …

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Aug 2022 • Nanomedicine: Nanotechnology, Biology and Medicine

Multifunctional nanoprobe for real-time in vivo monitoring of T cell activation

Oshra Betzer, Yue Gao, Astar Shamul, Menachem Motiei, Tamar Sadan, Ronen Yehuda, Ayelet Atkins, Cyrille J Cohen, Mingwu Shen, Xiangyang Shi, Rachela Popovtzer

Genetically engineered T cells are a powerful new modality for cancer immunotherapy. However, their clinical application for solid tumors is challenging, and crucial knowledge on cell functionality in vivo is lacking. Here, we fabricated a nanoprobe composed of dendrimers incorporating a calcium sensor and gold nanoparticles, for dual-modal monitoring of engineered T cells within a solid tumor. T cells engineered to express a melanoma-specific T-cell receptor and loaded with the nanoprobe were longitudinally monitored within melanoma xenografts in mice. Fluorescent imaging of the nanoprobe's calcium sensor revealed increased intra-tumoral activation of the T cells over time, up to 24 h. Computed tomography imaging of the nanoprobe's gold nanoparticles revealed the cells' intra-tumoral distribution pattern. Quantitative analysis revealed the intra-tumoral T cell quantities. Thus, this nanoprobe reveals intra …

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Aug 2022 • IEEE Photonics Journal

Measurement of the Second-Order Polarizability of Silver Nanoparticles With Reference-Free Hyper-Rayleigh Scattering for Entangled Photon Pair Interaction

Ariel Ashkenazy, Racheli Ron, Tchiya Zar, Hannah Aharon, Adi Salomon, Dror Fixler, Eliahu Cohen

Two-photon interactions of entangled-photon pairs with metallic nanoparticles (NPs) can be enhanced by localized surface-plasmon resonance. Recently, we have described how the properties of this quantum light-matter interaction can be deduced from classical second-harmonic generation measurements performed using a reference-free hyper-Rayleigh scattering method. Herein, we report the results of such classical-light characterization measurements. We obtain a large hyperpolarizability for the NPs, present the dependence of the hyperpolarizability on the NPs' spectral features, and show a dipolar emission pattern for the second-harmonic signal. Our results can be used to optimize entangled-photon pair interactions with metallic NPs to enable first ever detection of this process. Moreover, these results suggest that NPs may be used as source for ultra-broadband entangled-photon pairs through nonphase …

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Aug 2022 • Available at SSRN 3737807

Decomposition of Individual SNP Patterns from Mixed DNA Samples

Gabriel Azhari, Shamam Waldman, Netanel Ofer, Yosi Keller, Shai Carmi, Gur Yaari

Single Nucleotide Polymorphism markers (SNPs) have great potential to identify individuals, family relations, biogeographical ancestry, and phenotypic traits. In many forensic situations DNA mixtures of a victim and an unknown suspect exist. Extracting from such samples the suspect's SNP profile can be used to assist investigation and gather intelligence. Computational tools to determine inclusion/exclusion of a known individual from a mixture exist, but no algorithm to extract an unknown SNP profile without a list of suspects is available. We present here AH-HA, a novel computational approach for extracting an unknown SNP profile from a whole genome sequencing (WGS) of a two person mixture. It utilizes techniques similar to the ones used in haplotype phasing. It constructs the inferred genotype as an imperfect mosaic of haplotypes from a reference panel of the target population. It is shown to outperform more simplistic approaches, maintaining high performance through a wide range of sequencing depths (500x-5x). AH-HA can be applied in cases of victim-suspect mixtures and improve the capabilities of the investigating forces. This approach can be extended to more complex mixtures, with more donors and less prior information, further motivating the development of SNP based forensics technologies.

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Aug 2022 • ACS nano

Noninvasive Nanodiamond Skin Permeation Profiling Using a Phase Analysis Method: Ex Vivo Experiments

Channa Shapira, Daniel Itshak, Hamootal Duadi, Yifat Harel, Ayelet Atkins, Anat Lipovsky, Ronit Lavi, Jean Paul Lellouche, Dror Fixler

Carbon-based nanoparticles (NPs) are widely used in nanotechnology. Among them, nanodiamonds (NDs) are suitable for biotechnology and are especially interesting for skin delivery and topical treatments. However, noninvasive detection of NDs within the different skin layers or analyzing their penetration ability is complicated due to the turbid nature of the tissue. The iterative multiplane optical properties extraction (IMOPE) technique detects differences in the optical properties of the measured item by a phase-image analysis method. The phase image is reconstructed by the multiplane Gerchberg–Saxton algorithm. This technique, traditionally, detects differences in the reduced scattering coefficients. Here, however, due to the actual size of the NDs, the IMOPE technique’s detection relies on absorption analysis rather than relying on scattering events. In this paper, we use the IMOPE technique to detect the …

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Aug 2022 • Nature Physics

Topology-driven surface patterning of liquid spheres

Subhomoy Das, Alexander V Butenko, Yitzhak Mastai, Moshe Deutsch, Eli Sloutskin

Surfaces of classical spherical liquid droplets are isotropic, promoting the random distribution of surface-adsorbed molecules. Here we demonstrate a counterintuitive temperature-controlled self-assembly of well-defined and highly ordered patterns of surface-adsorbed fluorescent molecules on the surfaces of water-suspended spherical oil droplets. These patterns are induced by precisely self-positioned, topology-dictated structural defects in a crystalline monolayer covering these droplets’ surfaces over a wide temperature range. We elucidate the pattern formation mechanism, visualize the defects’ positions and map the stress fields within the surface crystal. The observed phenomena provide insights into the interfacial freezing effect on curved surfaces, enable precise positioning of functional ligands on droplets for their self-assembly into higher-hierarchy structures– and may also play an important role in vital …

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Aug 2022 • IEEE Photonics Journal

Measurement of the Second-Order Polarizability of Silver Nanoparticles With Reference-Free Hyper-Rayleigh Scattering for Entangled Photon Pair Interaction

Ariel Ashkenazy, Racheli Ron, Tchiya Zar, Hannah Aharon, Adi Salomon, Dror Fixler, Eliahu Cohen

Two-photon interactions of entangled-photon pairs with metallic nanoparticles (NPs) can be enhanced by localized surface-plasmon resonance. Recently, we have described how the properties of this quantum light-matter interaction can be deduced from classical second-harmonic generation measurements performed using a reference-free hyper-Rayleigh scattering method. Herein, we report the results of such classical-light characterization measurements. We obtain a large hyperpolarizability for the NPs, present the dependence of the hyperpolarizability on the NPs' spectral features, and show a dipolar emission pattern for the second-harmonic signal. Our results can be used to optimize entangled-photon pair interactions with metallic NPs to enable first ever detection of this process. Moreover, these results suggest that NPs may be used as source for ultra-broadband entangled-photon pairs through nonphase …

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Aug 2022 • Scientific Reports 12 (1), 1-9, 2022

Remote photonic detection of human senses using secondary speckle patterns

Zeev Kalyuzhner, Sergey Agdarov, Itai Orr, Yafim Beiderman, Aviya Bennett, Zeev Zalevsky

Neural activity research has recently gained signi cant attention due to its association with sensory information and behavior control. However, current methods of brain activity sensing require expensive equipment and physical contact with the subject.We propose a novel photonic-based method for remote detection of human senses. Physiological processes associated with hemodynamic activity due to activation of the cerebral cortex affected by different senses have been detected by remote monitoring of nano‐vibrations generated due to the transient blood ow to speci c regions of the brain. We have found that combination of defocused, self‐interference random speckle patterns with a spatiotemporal analysis using Deep Neural Network (DNN) allows associating between the activated sense and the seemingly random speckle patterns.

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Aug 2022 • ACS nano

Noninvasive Nanodiamond Skin Permeation Profiling Using a Phase Analysis Method: Ex Vivo Experiments

Channa Shapira, Daniel Itshak, Hamootal Duadi, Yifat Harel, Ayelet Atkins, Anat Lipovsky, Ronit Lavi, Jean Paul Lellouche, Dror Fixler

Carbon-based nanoparticles (NPs) are widely used in nanotechnology. Among them, nanodiamonds (NDs) are suitable for biotechnology and are especially interesting for skin delivery and topical treatments. However, noninvasive detection of NDs within the different skin layers or analyzing their penetration ability is complicated due to the turbid nature of the tissue. The iterative multiplane optical properties extraction (IMOPE) technique detects differences in the optical properties of the measured item by a phase-image analysis method. The phase image is reconstructed by the multiplane Gerchberg–Saxton algorithm. This technique, traditionally, detects differences in the reduced scattering coefficients. Here, however, due to the actual size of the NDs, the IMOPE technique’s detection relies on absorption analysis rather than relying on scattering events. In this paper, we use the IMOPE technique to detect the …

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Aug 2022 • Nature Physics

Topology-driven surface patterning of liquid spheres

Subhomoy Das, Alexander V Butenko, Yitzhak Mastai, Moshe Deutsch, Eli Sloutskin

Surfaces of classical spherical liquid droplets are isotropic, promoting the random distribution of surface-adsorbed molecules. Here we demonstrate a counterintuitive temperature-controlled self-assembly of well-defined and highly ordered patterns of surface-adsorbed fluorescent molecules on the surfaces of water-suspended spherical oil droplets. These patterns are induced by precisely self-positioned, topology-dictated structural defects in a crystalline monolayer covering these droplets’ surfaces over a wide temperature range. We elucidate the pattern formation mechanism, visualize the defects’ positions and map the stress fields within the surface crystal. The observed phenomena provide insights into the interfacial freezing effect on curved surfaces, enable precise positioning of functional ligands on droplets for their self-assembly into higher-hierarchy structures– and may also play an important role in vital …

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Aug 2022 • International Journal of Hydrogen Energy

Adsorption of bromine complexing agents on platinum electrocatalysts and prevention through polydopamine coatings

Samuel S Hardisty, Nagaprasad Reddy Samala, Ilya Grinberg, David Zitoun

Bromine complexing agents (BCAs) are seen as a promising route to mitigate the potential health and environmental risks of the bromine-based redox-flow batteries, like the hydrogen bromine redox flow battery (H2–Br2 RFB). The most studied BCAs are based on the pyridinium anion, which may adsorb and inhibit the Pt catalyst required in the H2–Br2 RFB system for the hydrogen reactions. Herein the effect of two BCAs (ethyl-pyridinium bromide and hexyl-pyridinium bromide) on a Pt electrocatalyst are studied, along with a potential methodology to prevent adsorption of the BCA through a polydopamine (PDA) coating. The results show that the pyridinium anion is adsorbed on Pt throughout a large potential range (−0.02 to 1.0 V), reducing the availability of the surface for the adsorption of other species. The PDA coating prevented this adsorption, but itself experiences adsorption of the BCA leading to some …

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Aug 2022 • ACS Applied Energy Materials

High-Energy Ni-Rich LiNi0.85Co0.1Mn0.05O2 Cathode Material for Li-Ion Batteries Enhanced by Nd- and Y-Doping. A Structural, Electrochemical, and Thermal …

Yehonatan Levartovsky, Arup Chakraborty, Sooraj Kunnikuruvan, Sandipan Maiti, Judith Grinblat, Michael Talianker, Doron Aurbach, Dan Thomas Major

Ni-rich LiNi1–x–yCoxMnyO2 (1 – x – y > 0.5) (NCMs) cathode materials have shown great promise in energy-intensive applications, such as electric vehicles. However, as many layered cathodes do, they suffer from structural and electrochemical degradation during cycling. In this study, we show that Nd- and Y-doped materials, Li(Ni0.85Co0.1Mn0.05)0.995Nd0.005O2 and Li(Ni0.85Co0.1Mn0.05)0.995Y0.005O2, have significantly better structural, electrochemical, and thermal properties compared to the reference LiNi0.85Co0.1Mn0.05O2 (NCM85) due to enhanced structural stability. The doped electrodes were found to have significantly higher specific discharge capacities, better capacity retention, and lower voltage hysteresis compared to the reference (undoped) electrodes. SEM images of the focused-ion beam (FIB) cut of the particles of the doped material showed that they have less cracks when compared …

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Aug 2022

Characterizing nanometric thin films with far-field light

Omer Shavit, Carine Julien, Ilya Olevsko, Mohamed Hamode, Yossi Abulafia, Hervé Suaudeau, Vincent Armand, Martin Oheim, Adi Salomon

Ultra-thin, transparent films are being used as protective layers on semiconductors, solar cells, as well as for nano-composite materials and optical coatings. Nano-sensors, photonic devices and calibration tools for axial super-resolution microscopies, all rely on the controlled fabrication and analysis of ultra-thin layers. Here, we describe a simple, non-invasive, optical technique for simultaneously characterizing the refractive index, thickness, and homogeneity of nanometric transparent films. In our case, these layers are made of the biomimetic polymer, My-133-MC, having a refractive index of 1.33, so as to approach the cytosol for biological applications. Our technique is based on the detection in the far field and the analysis of supercritical angle fluorescence (SAF), i.e., near-field emission from molecular dipoles located very close to the dielectric interface. SAF emanates from a 5-nm J-aggregate emitter layer deposited on and in contact with the inspected polymer film. Our results compare favorably to that obtained through a combination of atomic force and electron microscopy, surface-plasmon resonance spectroscopy and ellipsometry. We illustrate the value of the approach in two applications, (i), the measurement of axial fluorophore distance in a total internal reflection fluorescence geometry; and, (ii), axial super-resolution imaging of organelle dynamics in a living biological sample, cortical astrocytes, an important type of brain cell. In the later case, our approach removes uncertainties in the interpretation of the nanometric axial dynamics of fluorescently labeled vesicles. Our technique is cheap, versatile and it has obvious applications in …

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Aug 2022 • Current Opinion in Electrochemistry, 101107, 2022

Electrical Double Layer in Nano-Pores of Carbon Electrodes: Beyond CDI; Sensing and Maximizing Energy Extraction from Salinity Gradients

Eran Avraham, Barak Shapira, Izaak Cohen, Doron Aurbach

The important phenomenon of electrical double layer (EDL) is often described by mathematical relations between surface charges, variation of electrostatic potentials with distance and distribution of ions across the interface between charged surfaces (or particles) and electrolyte solutions. A major advance was made in the last decade in understanding complex EDL relationships with an emphasis on nano-porous carbonaceous materials. These understandings were usually exploited for the interpretation of electro-sorption phenomena connected to capacitive deionization (CDI) processes. The aim of this short paper is to demonstrate, based on previous studies, how models of EDL in nano-porous carbons can be the basis for modification of carbonaceous materials for other applications, like sensors and energy extraction from salinity gradients.

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Aug 2022 • Micromachines

Acoustic Manipulation of Intraocular Particles

Ari Leshno, Avraham Kenigsberg, Heli Peleg-Levy, Silvia Piperno, Alon Skaat, Hagay Shpaisman

Various conditions cause dispersions of particulate matter to circulate inside the anterior chamber of a human eye. These dispersed particles might reduce visual acuity or promote elevation of intraocular pressure (IOP), causing secondary complications such as particle related glaucoma, which is a major cause of blindness. Medical and surgical treatment options are available to manage these complications, yet preventive measures are not currently available. Conceptually, manipulating these dispersed particles in a way that reduces their negative impact could prevent these complications. However, as the eye is a closed system, manipulating dispersed particles in it is challenging. Standing acoustic waves have been previously shown to be a versatile tool for manipulation of bioparticles from nano-sized extracellular vesicles up to millimeter-sized organisms. Here we introduce for the first time a novel method utilizing standing acoustic waves to noninvasively manipulate intraocular particles inside the anterior chamber. Using a cylindrical acoustic resonator, we show ex vivo manipulation of pigmentary particles inside porcine eyes. We study the effect of wave intensity over time and rule out temperature changes that could damage tissues. Optical coherence tomography and histologic evaluations show no signs of damage or any other side effect that could be attributed to acoustic manipulation. Finally, we lay out a clear pathway to how this technique can be used as a non-invasive tool for preventing secondary glaucoma. This concept has the potential to control and arrange intraocular particles in specific locations without causing any damage to …

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Aug 2022 • ACS Applied Nano Materials

Dealloyed Octahedral PtCu Nanoparticles as High-Efficiency Electrocatalysts for the Oxygen Reduction Reaction

Melina Zysler, Enrique Carbo-Argibay, Paulo J Ferreira, David Zitoun

Pt-based nanoparticles (NPs) are used as electrocatalysts for the oxygen reduction reaction (ORR) that occurs at the cathode of a proton exchange membrane fuel cell, because of their high efficiency. Among these NPs, PtCu electrocatalysts are an important subclass, in which composition, morphology, size, crystal structure, and atomic distribution are tuned to optimize the performance and durability of the catalyst. Most of the efforts so far in the field have been dedicated toward increasing the catalytic activity and stability of these NPs, while reducing the amount of precious material. In this paper, we present a solvothermal method used for the synthesis of carbon-supported octahedral PtCu NPs that show high efficiency toward the ORR. In particular, a specific activity of 1.02 mA cm–2 was achieved after 10,000 cycles (accelerated degradation test) in which 84% of the electrochemical surface area was maintained …

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Jul 2022 • New Journal of Physics

Local equilibrium properties of ultraslow diffusion in the Sinai model

Amin Padash, Erez Aghion, Alexander Schulz, Eli Barkai, Aleksei V Chechkin, Ralf Metzler, Holger Kantz

We perform numerical studies of a thermally driven, overdamped particle in a random quenched force field, known as the Sinai model. We compare the unbounded motion on an infinite 1-dimensional domain to the motion in bounded domains with reflecting boundaries and show that the unbounded motion is at every time close to the equilibrium state of a finite system of growing size. This is due to time scale separation: Inside wells of the random potential, there is relatively fast equilibration, while the motion across major potential barriers is ultraslow. Quantities studied by us are the time dependent mean squared displacement, the time dependent mean energy of an ensemble of particles, and the time dependent entropy of the probability distribution. Using a very fast numerical algorithm, we can explore times up top steps and thereby also study finite-time crossover phenomena.

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Jul 2022 • Journal of The Electrochemical Society

Influence of Salt Anions on the Reactivity of Polymer Electrolytes in All-Solid-State Sodium Batteries

Shaul Bublil, Penki Tirupathi Rao, Yuval Elias, Miryam Fayena-Greenstein, Doron Aurbach

Solid-state batteries have received renewed attention in recent years. The present study compares all-solid-state sodium batteries containing polyethylene oxide (PEO) polymer electrolyte (PE) with two salts, NaPF6 and NaClO4. Electrochemical properties were determined by means of both AC and DC measurements. Battery prototypes with PEO:NaClO4 have a better specific capacity; however, a composite electrolyte system containing TiO2 nanoparticles shows greater influence in PEO:NaPF6. This is probably due to the titania particles acting as a scavenger of HF, an inevitable contaminant in electrolyte systems containing PF6- anions.

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Jul 2022 • Imaging Systems and Applications, IW1C. 4, 2022

Laser-Induced Tunable Focusing in Semiconductors

Nadav Shabairou, Zeev Zalevsky, Moshe Sinvani

We demonstrate a novel method for focusing a probe IR pulse laser beam in semiconductors. The shaping was done by a temporaly modifying the material complex refractive index by a second pulse pump laser beam absorbed in the sample, using pump-prob experiment.

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Jul 2022 • Journal of Power Sources

Influence of loading, metallic surface state and surface protection in precious group metal hydrogen electrocatalyst for H2/Br2 redox-flow batteries

Kobby Saadi, Samuel S Hardisty, Zhanna Tatus-Portnoy, David Zitoun

Performance, durability, and abundance/cost of electrocatalytic materials are fundamental parameters in for large electrochemical storage solutions like redox-flow batteries (RFB). The acidic environment in Hydrogen–Bromine RFB (HBRFB), which targets tens of thousands of hours in durability, makes the challenge even more acute. Continuous effort to find the most effective and stable catalyst can promote HBRFB goal to become sustainable for high power storage systems. Herein, we explore the lower limits in catalyst loading for the two most active precious group metals (PGMs) – platinum and iridium (individually and in a bimetallic catalyst). The catalyst has been structurally characterized and lab-scale redox-flow cells have been cycled with a decreasing loading of PGM. Carbon support and polymeric coating on Pt catalyst shows a significant increase in the utilization of the catalyst. It enables low platinum …

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