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Oct 2022 • Optics Continuum

16-channel O-band silicon-photonic wavelength division multiplexer with a 1 nm channel spacing

Matan Slook, Saawan Kumar Bag, Moshe Katzman, Dvir Munk, Yuri Kaganovskii, Michael Rosenbluh, Naor Inbar, Inbar Shafir, Leroy Dokhanian, Maayan Priel, Mirit Hen, Elad Zehavi, Avi Zadok

Silicon-photonic integrated circuits are a pivotal technology for the continued growth of data communications. A main task of silicon photonics is the wavelength division multiplexing of communication channels to aggregate bandwidths that exceed the working rates available in electronics. In this work, we design and implement a 16-channel, wavelength division multiplexing device in silicon-on-insulator. The device operates at the O-band wavelengths, centered at 1310 nm, which are favored by many data center applications. The spacing between adjacent channels is 0.96 nm (167 GHz), close to those of dense wavelength division multiplexing standards in the 1550 nm wavelength range (C band). The layout consists of 15 Mach-Zehnder interferometers, cascaded in a four-stage tree topology. The differential phase delay within each interferometer is precisely trimmed post-fabrication, through local illumination of a photosensitive upper cladding layer of As 2 Se 3 chalcogenide glass. Trimming is performed subject to closed-loop feedback of transfer functions measurements. The devices can be useful in data center optical communications.

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Oct 2022 • Physical Review B

Mixed superconducting state without applied magnetic field

Alex Khanukov, Itay Mangel, Shai Wissberg, Amit Keren, Beena Kalisky

A superconducting (SC) mixed state occurs in type-II superconductors where the upper critical field H c 2 is higher than the thermodynamic critical field H c. When an applied field is in between these fields, the free energy depends weakly on the order parameter which therefore can be small (SC state) or zero (normal state) at different parts of the sample. In this paper we demonstrate how a normal state along a line traversing a superconductor can be turned on and off externally in zero field. The concept is based on a long, current-carrying excitation coil, piercing a ring-shaped superconductor. The ring experiences zero field, but the vector potential produced by the coil generates a circular current that destroys superconductivity along a radial line starting at preexisting nucleation points in the sample. Unlike the destruction of superconductivity with magnetic field, the vector potential method is reversible and …

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Oct 2022 • Forward Brillouin Scattering in Standard Optical Fibers: Single-Mode …, 2022

Stimulated Forward Brillouin Scattering in Standard Single-Mode Fibers

Avi Zadok, Hilel Hagai Diamandi, Yosef London, Gil Bashan

The process of forward stimulated Brillouin scattering in standard single-mode fibers is described. The analysis brings together the electrostrictive stimulation of guided acoustic modes by a pair of co-propagating optical fields and the photoelastic scattering of the same two optical fields by the acoustic wave. The propagation of the optical fields is formulated in terms of nonlinear polarization components and coupled nonlinear wave equations. The solutions to the equation signify the coupling of optical power from the higher-frequency optical wave component to the lower-frequency one. Coupling is quantified by a nonlinear coefficient, with units of W−1 × m−1, the same one that was found earlier to describe spontaneous scattering processes. The stimulated Brillouin scattering between the pair of tones is also associated with the generation of spectral sidebands of increasing orders. The Brillouin scattering …

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Oct 2022 • Forward Brillouin Scattering in Standard Optical Fibers: Single-Mode …, 2022

Forward Brillouin Scattering in Polarization-Maintaining Fibers

Avi Zadok, Hilel Hagai Diamandi, Yosef London, Gil Bashan

Polarization-maintaining fibers support guided acoustic modes that are more complex than those of single-mode fibers, due to the presence of strain rods. Forward Brillouin scattering interactions in those fibers can be intra-modal as well as inter-modal. Intra-modal interactions involve the stimulation of guided acoustic waves by a pair of optical fields that co-propagate in a common principal axis. The intra-modal processes can lead to phase modulation of co-polarized optical probe signals, similar to standard single-mode fibers. The forward Brillouin scattering spectra differ between the two axes. In addition, acoustic modes stimulated through an intra-modal process in one axis may also modulate a probe wave in the orthogonal axis. Such inter-polarization cross-phase modulation is analogous to the dynamic gratings of backward Brillouin scattering in polarization-maintaining fibers. In inter-modal forward Brillouin …

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Oct 2022 • Forward Brillouin Scattering in Standard Optical Fibers: Single-Mode …, 2022

Experimental Results

Avi Zadok, Hilel Hagai Diamandi, Yosef London, Gil Bashan

Experimental characterization and applications of forward Brillouin scattering in various types of optical fibers are presented. Measurements are compared with the predictions of analysis and calculations whenever possible. Results include the forward Brillouin scattering spectra of bare and coated single-mode fibers, multi-core fibers, and polarization-maintaining fibers. Both intra-modal and inter-modal process in polarization-maintaining fibers are reported. The contributions of radial and torsional-radial modes are identified and classified. The interplay of forward Brillouin scattering and the Kerr effect is characterized as well. Position-integrated, point-measurement, and spatially distributed analyses of liquid media outside the fiber are demonstrated. The sensing of surrounding media is enabled by forward Brillouin scattering processes, even though guided light does not come in contact with such media. The …

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Oct 2022 • Forward Brillouin Scattering in Standard Optical Fibers: Single-Mode …, 2022

Introduction: Interactions Between Guided Optical and Acoustic Waves

Avi Zadok, Hilel Hagai Diamandi, Yosef London, Gil Bashan

In the first chapter of this book, the opto-mechanical effect of forward Brillouin scattering is introduced within a broader context of propagation effects in fibers and of interactions between optical and acoustic waves. A review of linear and nonlinear scattering phenomena is provided, including the mechanisms of Rayleigh, Raman, and Brillouin scattering, and the optical Kerr effect. Scattering from short-period and long-period grating devices is discussed as well. The potential applications and implications of the various mechanisms in optical fiber communications, sensing, signal processing, and lasing are briefly addressed. Next, the physical principles of opto-mechanics are introduced. These include the stimulation of elastic waves by electrostrictive bulk forces and radiation pressures and the scattering of optical waves through photoelasticity and moving boundary effects. Specific formalisms are developed for the …

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Oct 2022 • Communications biology

Affinity microfluidics enables high-throughput protein degradation analysis in cell-free extracts

Lev Brio, Danit Wasserman, Efrat Michaely-Barbiro, Gal Barazany-Gal, Doron Gerber, Amit Tzur

Protein degradation mediated by the ubiquitin-proteasome pathway regulates signaling events in many physiological and pathological conditions. In vitro degradation assays have been instrumental in the understanding of how cell proliferation and other fundamental cellular processes are regulated. These assays are direct, time-specific and highly informative but also laborious, typically relying on low-throughput polyacrylamide gel-electrophoresis followed by autoradiography or immunoblotting. We present protein degradation on chip (pDOC), a MITOMI-based integrated microfluidic technology for discovery and analysis of proteins degradation in cell-free extracts. The platform accommodates hundreds of microchambers on which protein degradation is assayed quickly, simultaneously and using minute amounts of reagents in one or many physiochemical environments. Essentially, pDOC provides a sensitive …

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Oct 2022 • Optics Continuum

16-channel O-band silicon-photonic wavelength division multiplexer with a 1 nm channel spacing

Matan Slook, Saawan Kumar Bag, Moshe Katzman, Dvir Munk, Yuri Kaganovskii, Michael Rosenbluh, Naor Inbar, Inbar Shafir, Leroy Dokhanian, Maayan Priel, Mirit Hen, Elad Zehavi, Avi Zadok

Silicon-photonic integrated circuits are a pivotal technology for the continued growth of data communications. A main task of silicon photonics is the wavelength division multiplexing of communication channels to aggregate bandwidths that exceed the working rates available in electronics. In this work, we design and implement a 16-channel, wavelength division multiplexing device in silicon-on-insulator. The device operates at the O-band wavelengths, centered at 1310 nm, which are favored by many data center applications. The spacing between adjacent channels is 0.96 nm (167 GHz), close to those of dense wavelength division multiplexing standards in the 1550 nm wavelength range (C band). The layout consists of 15 Mach-Zehnder interferometers, cascaded in a four-stage tree topology. The differential phase delay within each interferometer is precisely trimmed post-fabrication, through local illumination of a photosensitive upper cladding layer of As 2 Se 3 chalcogenide glass. Trimming is performed subject to closed-loop feedback of transfer functions measurements. The devices can be useful in data center optical communications.

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Oct 2022 • Forward Brillouin Scattering in Standard Optical Fibers: Single-Mode …, 2022

Forward Brillouin Scattering Spectra in Multi-core Fibers

Avi Zadok, Hilel Hagai Diamandi, Yosef London, Gil Bashan

In this chapter, the analysis of forward stimulated Brillouin scattering in fibers comprised of multiple cores is presented. In such multi-core fibers, guided acoustic waves may be stimulated by optical fields in one core and induce photoelastic scattering of light waves in a different one. The photoelastic scattering leads to cross-phase modulation among optical fields in spatially distinct cores, which is mediated by the stimulation of guided acoustic modes. Cross-phase modulation may take place even among cores that are spaced far apart, where the direct coupling of optical power is arbitrarily weak. The process is quantified in terms of the spectrum of forward Brillouin scattering coefficient, defined earlier with respect to single-mode fibers. The spectrum of cross-phase modulation between the inner, on-axis core and an outer, off-axis core is mediated by guided acoustic modes of radial symmetry and torsional-radial …

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Oct 2022 • Scientific Reports

Non-contact optical in-vivo sensing of cilia motion by analyzing speckle patterns

Doron Duadi, Nadav Shabairou, Adi Primov-Fever, Zeev Zalevsky

Cilia motion is an indicator of pathological-ciliary function, however current diagnosis relies on biopsies. In this paper, we propose an innovative approach for sensing cilia motility. We present an endoscopic configuration for measuring the motion frequency of cilia in the nasal cavity. The technique is based on temporal tracking of the reflected spatial distribution of defocused speckle patterns while illuminating the cilia with a laser. The setup splits the optical signal into two channels; One imaging channel is for the visualization of the physician and another is, defocusing channel, to capture the speckles. We present in-vivo measurements from healthy subjects undergoing endoscopic examination. We found an average motion frequency of around 7.3 Hz and 9.8 Hz in the antero-posterior nasal mucus (an area rich in cilia), which matches the normal cilia range of 7–16 Hz. Quantitative and precise measurements of …

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Oct 2022 • Nature communications

RNA export through the nuclear pore complex is directional

Asaf Ashkenazy-Titelman, Mohammad Khaled Atrash, Alon Boocholez, Noa Kinor, Yaron Shav-Tal

The changes occurring in mRNA organization during nucleo-cytoplasmic transport and export, are not well understood. Moreover, directionality of mRNA passage through the nuclear pore complex (NPC) has not been examined within individual NPCs. Here we find that an mRNP is compact during nucleoplasmic travels compared to a more open structure after transcription and at the nuclear periphery. Compaction levels of nuclear transcripts can be modulated by varying levels of SR proteins and by changing genome organization. Nuclear mRNPs are mostly rod-shaped with distant 5'/3'-ends, although for some, the ends are in proximity. The latter is more abundant in the cytoplasm and can be modified by translation inhibition. mRNAs and lncRNAs exiting the NPC exhibit predominant 5’-first export. In some cases, several adjacent NPCs are engaged in export of the same mRNA suggesting 'gene gating' …

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Oct 2022 • Materials Research Bulletin

In-situ design, characterization and use of durable superhydrophobic thin coatings applied on polymeric films

Naftali Kanovsky, Sarit Cohen, Shlomo Margel

Superhydrophobic coatings on polymeric films are in high demand due to their various real-world applications in a number of different fields. However, reported coatings lack durability or have complicated processes rendering them impractical. Here, tetraethylorthosilicate is polymerized via a modified Stöber method in the presence of a corona treated PP film (in-situ) which results in a thin silica-structured layer, covalently bonded to the PP film. Fluorocarbon silanes are then further reacted with the silica layer. The high surface roughness of the silica structures and low surface energy of the fluorocarbon silanes produce superhydrophobic surfaces. PP films coated with flake-like silica structures resulted in higher surface roughness and superhydrophobicity than the particle-like coating. Additionally, the flake-like silica coating exhibited good self-cleaning properties and durability to sandpaper abrasion tests. This …

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Oct 2022 • Communications materials

Nanomechanical signatures of degradation-free influence of water on halide perovskite mechanics

Isaac Buchine, Irit Rosenhek-Goldian, Naga Prathibha Jasti, Davide R Ceratti, Sujit Kumar, David Cahen, Sidney R Cohen

Humidity is often reported to compromise the stability of lead halide perovskites or of devices based on them. Here we measure the humidity dependence of the elastic modulus and hardness for two series of lead halide perovskite single crystals, varying either by cation or by anion type. The results reveal a dependence on bond length between, hydrogen bonding with, and polarizability/polarization of these ions. The results show an intriguing inverse relation between modulus and hardness, in contrast to their positive correlation for most other materials. This anomaly persists and is strengthened by the effect of humidity. This, and our overall findings are ascribed to the materials’ unique atomic-scale structure and properties, viz nano-polar domains and strong dynamic disorder, yet high-quality average order. Our conclusions are based on comparing results obtained from several different nano-indentation …

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Oct 2022 • Biomedical Photonics for Diabetes Research

11 Noninvasive Photonic Sensing

Nisan Ozana, Zeev Zalevsky

241 11.3 243 11.4 Magneto-Optic Effect-Based Measurements..................................................................... 245 11.5 Speckle-Based Sensing of Chemicals by an Acoustic Excitation in Aqueous Solutions... 249 Remote Sensing of Tissue Perfusion in the Lower Limbs.................................................. 250 11.6 11.7 Summary............................................................................................................................ 251 252 Acknowledgments References

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Oct 2022 • ACS Applied Materials & Interfaces

NiN-Passivated NiO Hole-Transport Layer Improves Halide Perovskite-Based Solar Cell

Anat Itzhak, Xu He, Adi Kama, Sujit Kumar, Michal Ejgenberg, Antoine Kahn, David Cahen

The interfaces between inorganic selective contacts and halide perovskites (HaPs) are possibly the greatest challenge for making stable and reproducible solar cells with these materials. NiOx, an attractive hole-transport layer as it fits the electronic structure of HaPs, is highly stable and can be produced at a low cost. Furthermore, NiOx can be fabricated via scalable and controlled physical deposition methods such as RF sputtering to facilitate the quest for scalable, solvent-free, vacuum-deposited HaP-based solar cells (PSCs). However, the interface between NiOx and HaPs is still not well-controlled, which leads at times to a lack of stability and Voc losses. Here, we use RF sputtering to fabricate NiOx and then cover it with a NiyN layer without breaking vacuum. The NiyN layer protects NiOx doubly during PSC production. Firstly, the NiyN layer protects NiOx from Ni3+ species being reduced to Ni2+ by Ar plasma …

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Oct 2022 • arXiv preprint arXiv:2110.12008

Super-resolution Imaging of Plasmonic Near-Fields: Overcoming Emitter Mislocalizations

Yuting Miao, Robert C Boutelle, Anastasia Blake, Vigneshwaran Chandrasekaran, Jennifer Hollingsworth, Shimon Weiss

Plasmonic nano-objects have shown great potential in enhancing biological and chemical sensing, light harvesting and energy transfer, and optical and quantum computing to name a few. Therefore, an extensive effort has been vested in optimizing plasmonic systems and exploiting their field enhancement properties. Super-resolution imaging with quantum dots (QDs) is a promising method to probe plasmonic near-fields, but is hindered by the distortion of the emission intensity and radiation pattern. Here we investigate the interaction between QDs and 'L-shaped' gold nanoantennas, and demonstrate both theoretically and experimentally that this strong interaction can induce polarization-dependent modifications to the apparent QD emission intensity, polarization and localization. Based on FDTD simulations and polarization-modulated single-molecule microscopy, we show that the displacement of the emitter's localization is due to the interference between the emitter and the induced dipole and can be up to 100 nm. We also discovered that the emission polarization can rotate towards the symmetry axis or one arm of the L-shape because of the scattering. Our results could assist in paving a pathway for higher precision plasmonic near-field mapping and its underlying applications.

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Oct 2022 • iScience

A seven-transmembrane protein-TM7SF3, resides in nuclear speckles and regulates alternative splicing

Roi Isaac, Yaron Vinik, Martin Mikl, Shani Nadav-Eliyahu, Hadas Shatz-Azoulay, Adi Yaakobi, Natalie DeForest, Amit R Majithia, Nicholas JG Webster, Yaron Shav-Tal, Eytan Elhanany, Yehiel Zick

The seven-transmembrane superfamily member 3 protein (TM7SF3) is a p53-regulated homeostatic factor that attenuates cellular stress and the unfolded protein response. Here we show that TM7SF3 localizes to nuclear speckles; eukaryotic nuclear bodies enriched in splicing factors. This unexpected location for a trans-membranal protein enables formation of stable complexes between TM7SF3 and pre-mRNA splicing factors including DHX15, LARP7, HNRNPU, RBM14, and HNRNPK. Indeed, TM7SF3 regulates alternative splicing of >330 genes, mainly at the 3’end of introns by directly modulating the activity of splicing factors such as HNRNPK. These effects are observed both in cell lines and primary human pancreatic islets. Accordingly, silencing of TM7SF3 results in differential expression of 1465 genes (about 7% of the human genome); with 844 and 621 genes being up- or down-regulated, respectively …

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Oct 2022 • ACS Applied Materials & Interfaces

Unique Mechanisms of Ion Storage in Polyaniline Electrodes for Pseudocapacitive Energy Storage Devices Unraveled by EQCM-D Analysis

Meital Turgeman, Gil Bergman, Amey Nimkar, Bar Gavriel, Elad Ballas, Fyodor Malchik, Mikhael D Levi, Daniel Sharon, Netanel Shpigel, Doron Aurbach

The optimal performance of organic electrodes for aqueous batteries requires their full compatibility with selected electrolyte solutions. Electrode materials having 1–3-dimensional structures of variable rigidity possess a confined space in their structure filled with water and electrolyte solutions. Depending on the rigidity and confined space geometry, insertion and extraction of ions into electrode structures are often coupled with incorporation/withdrawal of water molecules. Aside from the scientific interest in understanding the charging mechanism of such systems, co-insertion of solvent molecules affects strongly the charge storage capability of the electrodes for energy storage devices. We present herein in situ electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) investigations of polyaniline (PANI) electrodes operating in various aqueous Na+-containing electrolytes, namely, Na2SO4 …

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Oct 2022 • Advanced Science

Highly Stable 4.6 V LiCoO2 Cathodes for Rechargeable Li Batteries by Rubidium‐Based Surface Modifications

Tianju Fan, Yujie Wang, Villa Krishna Harika, Amey Nimkar, Kai Wang, Xiaolang Liu, Meng Wang, Leimin Xu, Yuval Elias, Hadar Scalar, Munseok S Chae, Yonggang Min, Yuhao Lu, Netanel Shpigel, Doron Aurbach

Among extensively studied Li‐ion cathode materials, LiCoO2 (LCO) remains dominant for portable electronic applications. Although its theoretical capacity (274 mAh g−1) cannot be achieved in Li cells, high capacity (≤240 mAh g−1) can be obtained by raising the charging voltage up to 4.6 V. Unfortunately, charging Li‐LCO cells to high potentials induces surface and structural instabilities that result in rapid degradation of cells containing LCO cathodes. Yet, significant stabilization is achieved by surface coatings that promote formation of robust passivation films and prevent parasitic interactions between the electrolyte solutions and the cathodes particles. In the search for effective coatings, the authors propose RbAlF4 modified LCO particles. The coated LCO cathodes demonstrate enhanced capacity (>220 mAh g−1) and impressive retention of >80/77% after 500/300 cycles at 30/45 °C. A plausible mechanism …

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Oct 2022 • Protein Science

Copper coordination states affect the flexibility of copper Metallochaperone Atox1: Insights from molecular dynamics simulations

Renana Schwartz, Sharon Ruthstein, Dan Thomas Major

Copper is an essential element in nature but in excess it is toxic to the living cell. The human metallochaperone Atox1 participates in copper homeostasis and is responsible for copper transmission. In a previous multiscale simulation study, we noticed a change in the coordination state of the Cu(I) ion, from 4 bound cysteine residues to 3, in agreement with earlier studies. Here we perform and analyse classical molecular dynamic simulations of various coordination states: 2, 3, and 4. The main observation is an increase in protein flexibility as a result of a decrease in coordination state. Additionally, we identified several populated conformations that correlate well with double electron‐electron resonance distance distributions or an X‐ray structure of Cu(I)‐bound Atox1. We suggest that the increased flexibility might benefit the process of ion transmission between interacting proteins. Further experiments can …

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Oct 2022 • ACS Omega

Cooperative Intrinsic Basicity and Hydrogen Bonding Render SmI2 More Azaphilic than Oxophilic

Gil Kolin, Renana Schwartz, Daniel Shuster, Dan Thomas Major, Shmaryahu Hoz

It has been recently shown that SmI2 is more azaphilic than oxophilic. Density functional theory calculations reveal that coordination of 1–3 molecules of ethylenediamine is more exothermic by up to 10 kcal/mol than coordination of the corresponding number of ethylene glycol molecules. Taking into account also hydrogen bonds between ligands and tetrahydrofuran doubles this preference. The intrinsic affinity parallels the order of basicity. The cooperativity with the hydrogen bonding makes SmI2 more azaphilic than oxophilic.

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