BINA

Identifying and investigating protein–DNA interactions, which play significant roles in many biological processes, is essential for basic and clinical research. Current techniques for identification of protein–DNA interactions are laborious, time-consuming, and suffer from nonspecific binding and limited sensitivity. To overcome these challenges and assess protein–DNA interactions, we use a magnetic modulation biosensing (MMB) system. In MMB, one of the interacting elements (protein or DNA) is immobilized to magnetic beads, and the other is coupled to a fluorescent molecule. Thus, the link between the magnetic bead and the fluorescent molecule is established only when binding occurs, enabling detection of the protein–DNA interaction. Using magnetic forces, the beads are concentrated and manipulated in a periodic motion in and out of a laser beam, producing a detectable oscillating signal. Using MMB, we …

Forward stimulated Brillouin scattering in standard single‐mode fibers draws increasing interest toward sensing and signal processing applications. The process takes place through two classes of guided acoustic modes: purely radial ones and torsional‐radial modes with twofold azimuthal symmetry. The latter case cannot be described in terms of scalar models alone. In this work, the polarization attributes of forward stimulated Brillouin scattering in single‐mode fibers are investigated in analysis and experiment. Torsional‐radial acoustic modes are stimulated by orthogonally polarized pump tones, a first such report in standard single‐mode fibers. The scattering of optical probe waves by torsional‐radial modes may take up the form of phase modulation, cross‐polarization coupling, or a combination of both, depending on polarization. Lastly, this analysis predicts that circular and orthogonal pump tones may …

CRISPR-Cas technology has revolutionized gene editing, but concerns remain due to its propensity for off-target interactions. This, combined with genotoxicity related to both CRISPR-Cas9-induced double-strand breaks and transgene delivery, poses a significant liability for clinical genome-editing applications. Current best practice is to optimize genome-editing parameters in preclinical studies. However, quantitative tools that measure off-target interactions and genotoxicity are costly and time-consuming, limiting the practicality of screening large numbers of potential genome-editing reagents and conditions. Here, we show that flow-based imaging facilitates DNA damage characterization of hundreds of human hematopoietic stem and progenitor cells per minute after treatment with CRISPR-Cas9 and recombinant adeno-associated virus serotype 6. With our web-based platform that leverages deep learning for …

Copper is a trace element vital to many cellular functions. Yet its abnormal levels are toxic to cells, provoking a variety of severe diseases. The high affinity Copper Transporter 1 (CTR1), being the main in-cell copper (Cu(I)) entry route, tightly regulates its cellular uptake via a still elusive mechanism. Here, all-atoms simulations unlock the molecular terms of Cu(I) transport in eukaryotes disclosing that the two Methionine triads, forming the selectivity filter, play an unprecedented dual role both enabling selective Cu(I) transport and regulating its uptake-rate thanks to an intimate coupling between the conformational plasticity of their bulky side chains and the number of bound Cu(I) ions. Namely, the Met residues act as a gate reducing the Cu(I) import-rate when two ions simultaneously bind to CTR1. This may represent an elegant autoregulatory mechanism through which CTR1 protects the cells from excessively high, and hence toxic, in-cell Cu(I) levels. Overall, these outcomes resolve fundamental questions in CTR1 biology and open new windows of opportunity to tackle diseases associated with an imbalanced copper uptake.

If disorder-induced Anderson localized states have been observed experimentally in optics, their study remains challenging leaving a number of open questions unsolved. Among them, the impact on Anderson localization of non-Hermiticity, optical gain and loss, and more generally, nonlinearities has been the subject of numerous theoretical debates, without yet any conclusive experimental demonstration. Indeed, in systems where localized modes have reasonable spatial extension to be observed and investigated, their mutual interaction and coupling to the sample boundaries make it extremely difficult to isolate them spectrally and investigate them alone. Recently, we successfully exhibited localized lasing modes individually in an active disordered medium, using pump-shaping optimization technique. However, a one-to-one identification of the lasing modes with the eigenmodes of the passive system was not possible, as the impact of non-Hermiticity and nonlinear gain on these localized states was unknown. Here, we apply the pump-shaping method to fully control the non-Hermiticity of an active scattering medium. Direct imaging of the light distribution within the random laser allows us to demonstrate unequivocally that the localized lasing modes are indeed the modes of the passive system. This opens the way to investigate the robustness of localized states in the presence of nonlinear gain and nonlinear modal interactions. We show that, surprisingly, gain saturation and mode competition for gain does not affect the spatial distribution of the modes.

Similarly to other transition metal sulfides, nickel sulfide nanocrystals can be potentially used for functional device applications. However, controlling morphology and stoichiometry to target specific applications is a synthesis challenge. In this work we developed a rapid, one-step, chemical vapor deposition synthesis of nickel sulfide dendritic nanostructures with fractal geometry. Microtome-EDS compositional analysis of the mature crystal indicates a trend of decreasing sulfur and increasing nickel concentration towards the tip of the mature crystals. Following thorough investigation of these nanocrystals at different stages of their nucleation and growth by means of XRD, HR-SEM, HR-TEM, and Raman spectroscopy, we suggest possible kinetic mechanisms for the crystal formation and development. This work contributes to the understanding of growth mechanisms of dendritic structures with complex morphology.

Transition-metal dichalcogenides (TMDCs) are unique layered materials with exotic properties. So, examining their structures holds tremendous importance. 2H-MoSe2 (analogous to MoS2; Gr. 6 TMDC) is a crucial optoelectronic material studied extensively using Raman spectroscopy. In this regard, low-frequency Raman (LFR) spectroscopy can probe this material’s structure as it reveals distinct vibration modes. Here, we focus on understanding the microstructural evolution of different 2H-MoSe2 morphologies and their layers using LFR scattering. We grew phase-pure 2H-MoSe2 (with variable microstructures) directly on a Mo foil using a two-furnace ambient-pressure chemical vapor deposition (CVD) system by carefully controlling the process parameters. We analyzed the layers of exfoliated flakes after ultrasonication and drop-cast 2H-MoSe2 of different layer thicknesses by choosing different concentrations of …

The global energy demand is expected to rise continuously in the foreseeable future, and this demand cannot be fulfilled with fossil fuels if the ambitious goals for global reduction in greenhouse gas emissions are to be met. 1, 2 Therefore, it is necessary to switch to energy production from sustainable energy sources such as solar and wind. 3, 4 These sources suffer from intermittent production, producing a surplus of energy at certain hours and seasons and little to none at others. Hence, large energy storage solutions are necessary in order to store the excess energy in peak times and compensate at the lowand down-times. 4, 5One of the most promising energy storage solutions today is chemical, in the form of hydrogen, which can be used with fuel cells to generate electricity or burned to generate heat, as well as being used in the chemical industry for various applications. 5 It can be easily produced with various …

The functionality of a nanoscale silicon-based optoelectronic modulator is deeply analyzed while it appears that two competing processes, thermal and photonic, are occurring at the same time, and are preventing the optimization of the electro-optics coupling. While an incident illumination-beam first process is translated into photons, generating pairs of electrons–holes, a second process of thermal generation, creating phonons enables a loss of energy. Complementary studies, combining strong analytical models and numerical simulations, enabled to better understand this competition between photonic and thermal activities, in order to optimize the modulator. Moreover, in order to prevent unnecessary heating effects and to present a proposed solution, a picosecond pulsed laser is suggested and demonstrated as the ultimate solution so no energy will be wasted in heat, and still the photonic energy will be fully …

Quantum tunneling (QT) is not an effect often considered in chemistry, and rightfully so. However, in many cases it is significant, and in some cases it is even considerable. In this chapter we will describe the basic tenets of QT with a focus on catalysis, followed by some of the most important tools to study and compute them. The chapter goes on to address the title of the chapter by discussing several clear cases of QT for hydrogen-based reactions in organometallic, enzymatic, astrochemical, and organic systems. The insights highlighted in the chapter showcase the importance of QT in specific catalyzed reactions and help uncover the instances that are worth of attention.

This paper proposes a method for a scheme of spectral phase encoding with resolution of up to 10 MHz and addressability of 40GHz, for a typical wide-band optical data carrying signal, by means of optical instruments and prior knowledge about the signal. The setup includes an array of Fabri-Perot Interferometers (FPI) which bypass the grating limitations, and a phase-only spatial light modulator (SLM) to properly encode the diffracted light. Their arrangement along with the method of Optical Code Division Multiple Access (OCDMA) was simulated, and promised fine results for various encoding schemes.

Direct detection of intrinsic defects in halide perovskites (HaPs) by standard methods utilizing optical excitation is quite challenging, due to the low density of defects in most samples of this family of materials (≤ 1015 cm− 3 in polycrystalline thin films and≤ 1011 cm− 3 in single crystals, except melt-grown ones). While several electrical methods can detect defect densities< 1015 cm− 3, such as deep level transient spectroscopy (DLTS) or thermally stimulated current (TSC), they require preparation of ohmic and/or rectifying electrical contacts to the sample, which not only poses a challenge by itself in the case of HaPs but also may create defects at the contact− HaP interface and introduce extrinsic defects into the HaP. Here, we show that low-energy photoelectron spectroscopy measurements can be used to obtain directly the energy position of gap states in Br-based wide-bandgap (Eg> 2 eV) HaPs. By measuring HaP layers on both hole-and electron-contact layers, as well as single crystals without contacts, we conclude that the observed deep defects are intrinsic to the Br-based HaP, and we propose a passivation route via the incorporation of a 2D-forming ligand into the precursor solution.

The stimulation of the guided acoustic modes of standard single-mode fibers by co-propagating optical field components is formulated. Effective stimulation requires that the electrostrictive force induced by optical waves and the displacement of the acoustic mode share the same temporal frequency and axial wavenumber. These conditions, in turn, are satisfied at acoustic frequencies that are close to the modal cutoff. The frequency dependence of modal stimulation follows a Lorentzian line shape. The strengths of the modal stimulation scale with the beating power between two optical field components. In addition, the stimulation efficiency scales with the overlap integral between the transverse profiles of force and acoustic displacement. The transverse symmetry of the electrostrictive force restricts the stimulation to guided acoustic modes that are either purely radial or torsional-radial with twofold azimuthal …

Atomic and molecular layer deposition (ALD and MLD) are techniques based on surface‐directed self‐limiting reactions that afford deposition of films controlled at the monolayer level and with extreme conformality, even on ultra‐high‐aspect‐ratio and porous substrates. These methodologies are typically used to deposit thin films with desirable physical properties and functionality. Here, the MLD process is harnessed to demonstrate the growth of molecularly thin chiral films that inherit a desirable chemical property directly from the source precursor: using this innovative technique, enantioselective nanosurfaces are managed to be grown. Specifically, the formation of a Zn/Cysteine nanostructure by MLD is demonstrated for both the l‐ and d‐ enantiomers. The reaction and growth mechanism of these chiral hybrid inorganic‐organic nanosurfaces are studied via various experimental procedures; their …

The photoelastic perturbations to the dielectric tensor in standard single-mode fibers, due to the oscillations of guided acoustic modes, are studied and formulated. Material displacement of acoustic modes is associated with local strain in every point within the fiber cross section. Strain, in turn, gives rise to dielectric perturbations, which scale with the magnitude of the acoustic modal displacement. The photoelastic perturbations propagate along the fiber axis with the frequency and wavenumber of the acoustic wave and may scatter and modulate optical fields. The effect of the photoelastic perturbations on guided light depends on the spatial overlap between their transverse profile and that of the optical mode. The position-averaged perturbations associated with radial modes are scalar, and their effect on guided light is independent of polarization. Torsional-radial acoustic modes, on the other hand, induce …

Recent patents relating to CRISPR methods and compositions for gene editing and therapeutic use.

The analysis of forward stimulated Brillouin scattering is extended to standard single-mode fibers with coating layers. The cutoff frequencies, linewidths, and transverse profiles of the guided acoustic modes are modified by the presence of the coating layer and by its mechanical properties. The solutions are generally more complex than those of bare, uncoated fibers. Nevertheless, the boundary conditions can be brought into the form of matrix coefficients and solved to obtain the guided modes of the coated fibers. The forward stimulated Brillouin scattering of coated fibers is highly sensitive of submicron variations in the thickness of the coating layer, due to interference effects. Some modes are more sensitive to such variations than others. In contrast to bare fibers, the forward Brillouin scattering linewidths of coated fibers do not maintain a one-to-one correspondence with the mechanical impedance of media outside …

The final chapter of the book provides a brief recap of forward Brillouin scattering in standard optical fibers, directions for possible further research, and the prospects and challenges associated with technological applications of the effect.

Attempts to dope halide perovskites (HaPs) extrinsically have been mostly unsuccessful. Still, oxygen (O2) is an efficient p‐dopant for polycrystalline HaP films. To an extent, this doping is reversible, i.e., the films can be de‐doped by decreasing the O2 partial pressure. Here results are reported, aimed at understanding the mechanism of such reversible doping, as it has been argued that doping involves interaction of oxygen with defects inside bulk HaP. These experimental results clearly point out that O2‐surface interactions suffice to dope the bulk of the films. Such behavior fits what is known for other polycrystalline semiconductors, where surface charge transfer‐adducts can form and be removed. Thus, controlling the O2 partial pressure to which the HaP film is exposed, can, after proper encapsulation, achieve the desired bulk doping of the film.