All-optical nonreciprocity due to valley polarization pumping in transition metal dichalcogenides.

Nonreciprocity and nonreciprocal optical devices play a vital role in modern photonic technologies by enforcing one-way propagation of light. Here, we demonstrate an all-optical approach to nonreciprocity based on valley-selective response in transition metal dichalcogenides (TMDs). This approach overcomes the limitations of magnetic materials and it does not require an external magnetic field.

A parasitoid wasp of Drosophila employs preemptive and reactive strategies to deplete its host's blood cells.

The wasps Leptopilina heterotoma parasitize and ingest their Drosophila hosts. They produce extracellular vesicles (EVs) in the venom that are packed with proteins, some of which perform immune suppressive functions. EV interactions with blood cells of host larvae are linked to hematopoietic depletion, immune suppression, and parasite success.

Shear response of granular packings compressed above jamming onset.

We investigate the mechanical response of jammed packings of repulsive, frictionless spherical particles undergoing isotropic compression. Prior simulations of the soft-particle model, where the repulsive interactions scale as a power law in the interparticle overlap with exponent α, have found that the ensemble-averaged shear modulus 〈G(P)〉 increases with pressure P as ∼P^{(α-3/2)/(α-1)} at large pressures. 〈G〉 has two key contributions: (1) continuous variations as a function of pressure along geometrical families, for which the interparticle contact network does not change, and (2) discontinuous jumps during compression that arise from changes in the contact network.

Near-Field Characterization of Higher-Order Topological Photonic States at Optical Frequencies.

Higher-order topological insulators (HOTIs) represent a new type of topological system, supporting boundary states localized over boundaries, two or more dimensions lower than the dimensionality of the system itself. Interestingly, photonic HOTIs can possess a richer physics than their original condensed matter counterpart, supporting conventional HOTI states based on tight-binding coupling, and a new type of topological HOTI states enabled by long-range interactions. Here, a new mechanism to establish all-dielectric infrared HOTI metasurfaces exhibiting both types of HOTI states is proposed, supported by a topological transition accompanied by the emergence of topological Wannier-type polarization.

Photosynthesis on the Ultrafast Time Scale within the Confinements of Quantum Nanostructured Photosystems.

Fundamental information on the behavior of excited chlorophyll molecules packed within the confinements of nanosized photosystems I and II, following absorption of light, is presented. Using a 100 femtosecond laser with nanojoule (nJ) pulse energy and a one picosecond streak camera, we observed the light emitted from the nanostructured photosystems without oscillations or hops. The fluorescent exponential decay profiles and high efficiency within the nanostructure suggest that light coherently drains out as a unit.

Resistance Mechanisms of Anti-angiogenic Therapy and Exosomes-Mediated Revascularization in Cancer.

Anti-angiogenic therapies (AATs) have been widely used for cancer treatment. But the beneficial effects of AATs are short, because AAT-induced tumor revascularization facilitates the tumor relapse. In this mini-review, we described different forms of tumor neovascularization and revascularization including sprouting angiogenesis, vessel co-option, intussusceptive angiogenesis, and vasculogenic mimicry, all of which are closely mediated by vascular endothelial growth factor (VEGF), angiopoietins, matrix metalloproteinases, and exosomes.

Limited Sensitivity of Hippocampal Synaptic Function or Network Oscillations to Unmodulated Kilohertz Electric Fields.

Understanding the cellular mechanisms of kilohertz (kHz) electrical stimulation is of broad interest in neuromodulation including forms of transcranial electrical stimulation, interferential stimulation, and high-rate spinal cord stimulation (SCS). Yet, the well-established low-pass filtering by neuronal membranes suggests minimal neuronal polarization in respond to charge-balanced kHz stimulation. The hippocampal brain slice model is among the most studied systems in neuroscience and exhaustively characterized in screening the effects of electrical stimulation.

Neurocomputational mechanisms of prior-informed perceptual decision-making in humans.

To interact successfully with diverse sensory environments, we must adapt our decision processes to account for time constraints and prior probabilities. The full set of decision-process parameters that undergo such flexible adaptation has proven to be difficult to establish using simplified models that are based on behaviour alone. Here, we utilize well-characterized human neurophysiological signatures of decision formation to construct and constrain a build-to-threshold decision model with multiple build-up (evidence accumulation and urgency) and delay components (pre- and post-decisional).

Temporal interference stimulation targets deep brain regions by modulating neural oscillations.

Background: Temporal interference (TI) stimulation of the brain generates amplitude-modulated electric fields oscillating in the kHz range with the goal of non-invasive targeted deep brain stimulation. Yet, the current intensities required in human (sensitivity) to modulate deep brain activity and if superficial brain region are spared (selectivity) at these intensities remains unclear.

Objective: We developed an experimentally constrained theory for TI sensitivity to kHz electric field given the attenuation by membrane low-pass filtering property, and for TI selectivity to deep structures given the distribution of modulated and unmodulated electric fields in brain.

Modulation of solute diffusivity in brain tissue as a novel mechanism of transcranial direct current stimulation (tDCS).

The breadth of brain disorders and functions reported responsive to transcranial direct current stimulation (tDCS) suggests a generalizable mechanism of action. Prior efforts characterized its cellular targets including neuron, glia and endothelial cells. We propose tDCS also modulates the substance transport in brain tissue.

Transcellular Model for Neutral and Charged Nanoparticles Across an In Vitro Blood-Brain Barrier.

Purpose: The therapeutic drug-loaded nanoparticles (NPs, 20-100 nm) have been widely used to treat brain disorders. To improve systemic brain delivery efficacy of these NPs, it is necessary to quantify their transport parameters across the blood-brain barrier (BBB) and understand the underlying transport mechanism.

Methods: Permeability of an in vitro BBB, bEnd3 (mouse brain microvascular endothelial cells) monolayer, to three neutral NPs with the representative diameters was measured using an automated fluorometer system.

Emerging Structural and Interfacial Features of Particulate Polymers at the Nanoscale.

Particulate polymers at the nanoscale are exceedingly promising for diversified functional applications ranging from biomedical and energy to sensing, labeling, and catalysis. Tailored structural features (i.e.

The Occupational Depression Inventory: A new tool for clinicians and epidemiologists.

Background: Depressive symptoms induced by insurmountable job stress and sick leave for mental health reasons have become a focal concern among occupational health specialists. The present study introduces the Occupational Depression Inventory (ODI), a measure designed to quantify the severity of work-attributed depressive symptoms and establish provisional diagnoses of job-ascribed depression. The ODI comprises nine symptom items and a subsidiary question assessing turnover intention.

Numerical study on the adhesion of a circulating tumor cell in a curved microvessel.

The adhesion of a circulating tumor cell (CTC) in a three-dimensional curved microvessel was numerically investigated. Simulations were first performed to characterize the differences in the dynamics and adhesion of a CTC in the straight and curved vessels. After that, a parametric study was performed to investigate the effects of the applied driven force density f (or the flow Reynolds number Re) and the CTC membrane bending modulus K on the CTC adhesion.

Blood-Brain Barrier (BBB) Permeability and Transport Measurement In Vitro and In Vivo.

Quantification of the blood-brain barrier (BBB) permeability and transport in brain tissue is crucial in understanding brain disorders and developing systemic and non-systemic drug delivery strategies to the brain. This chapter summarizes BBB permeability measurement in vitro (Part I) and the in vivo non-invasive methods for quantifying the BBB permeability to solutes and brain tissue transport in rat brain by employing intravital multiphoton microscopy and a curving fitting method by using an unsteady mass transfer mathematical model (Part II).

Prediction of improved therapeutics for fabry disease patients generated by mutagenesis of the α-galactosidase A active site, dimer interface, and glycosylation region.

Fabry disease is an X-linked lysosomal storage disorder caused by the deficiency of the enzyme, α-galactosidase A that induces the accumulation of the substrate globotriaosylceramide. Currently approved enzyme replacement therapy using recombinant human α-galactosidase A improves patient symptoms but a majority of patients experience adverse events due to the multiple infusions required for full therapeutic efficacy. Our approach is to use medicinal chemistry and phylogenic comparisons to introduce mutations into the human enzyme to increase catalytic activity and/or stability to generate an improved therapeutic enzyme that may require fewer infusions.

Fluorescence Emission Triggered by Radioactive decay in Optimized Hyperbolic Cavities.

Luminescence arising from -decay of radiotracers has garnered much interest recently as a viable in-vivo imaging technique. The emitted Cerenkov radiation can be directly detected by high sensitivity cameras or used to excite highly efficient fluorescent dyes. Here, we investigate the enhancement of visible and infrared emission driven by -decay of radioisotopes in the presence of a hyperbolic nanocavity.

Superconductivity in graphene induced by the rotated layer.

Recent discoveries in graphene bilayers have revealed that when one of the layers is rotated by a specific angle, superconductivity emerges. We provide an explanation for this phenomenon. We find that due to the layer rotation the spinors and the nodal Dirac points also depend on the rotation angle.

Relative contributions of Franck-Condon to Herzberg-Teller terms in charge transfer surface-enhanced Raman scattering spectroscopy.

We have theoretically modeled charge transfer (CT) surface enhanced raman scattering (SERS) spectroscopy using pyridine bound to a planar Ag metal nanocluster. CT states were determined by natural transition orbital hole-particle plots and CT distance D and the amount of charge transferred q indices. We first consider a resonance Raman (RR) model based on the Albrecht approach and calculate the ratio of the Herzberg-Teller (HT) B or C term to the Franck-Condon (FC) A term for a totally symmetric a vibrational mode exciting in the lowest energy CT state.

Mechanical and Self-Healing Behavior of Matrix-Free Polymer Nanocomposites Constructed via Grafted Graphene Nanosheets.

Through molecular dynamics (MD) simulation, the structure and mechanical properties of matrix-free polymer nanocomposites (PNCs) constructed via polymer-grafted graphene nanosheets are studied. The dispersion of graphene sheets is characterized by the radial distribution function (RDF) between graphene sheets. We observe that a longer polymer chain length leads to a relatively better dispersion state attributed to the formation of a better brick-mud structure, effectively screening the van der Waals interactions between sheets.

Virtual Parity-Time Symmetry.

Parity-time (PT) symmetry has recently been opening exciting directions in photonics, yet the required careful balance of loss and gain has been hindering its widespread applicability. Here, we propose a gain-free route to PT symmetry by extending it to complex-frequency excitations that can mimic gain in passive systems. Based on the concept of virtual absorption, extended here to implement also virtual gain, we implement PT symmetry in the complex-frequency plane and realize its landmark effects, such as broken phase transitions, anisotropic transmission resonances, and laser-absorber pairs, in a fully passive, hence inherently stable, system.

γ-Secretase Partitioning into Lipid Bilayers Remodels Membrane Microdomains after Direct Insertion.

γ-Secretase is a multisubunit complex that catalyzes intramembranous cleavage of transmembrane proteins. The lipid environment forms membrane microdomains that serve as spatio-temporal platforms for proteins to function properly. Despite substantial advances in the regulation of γ-secretase, the effect of the local membrane lipid microenvironment on the regulation of γ-secretase is poorly understood.

Optimization of interferential stimulation of the human brain with electrode arrays.

Objective: Interferential stimulation (IFS) has generated considerable interest recently because of its potential to achieve focal electric fields in deep brain areas with transcranial currents. Conventionally, IFS applies sinusoidal currents through two electrode pairs with close-by frequencies. Here we propose to use an array of electrodes instead of just two electrode pairs; and to use algorithmic optimization to identify the currents required at each electrode to target a desired location in the brain.