Engineering anisotropic electrodynamics at the graphene/CrSBr interface.

Graphene is a privileged 2D platform for hosting confined light-matter excitations known as surface plasmon polaritons (SPPs), as it possesses low intrinsic losses and a high degree of optical confinement. However, the isotropic nature of graphene limits its ability to guide and focus SPPs, making it less suitable than anisotropic elliptical and hyperbolic materials for polaritonic lensing and canalization. Here, we present graphene/CrSBr as an engineered 2D interface that hosts highly anisotropic SPP propagation across mid-infrared and terahertz energies.

Galactose Impairs Motor Performance and Cerebellar Signaling in Young Male Wistar Rats.

Galactosemias are a group of inborn errors of galactose metabolism that causes different motor symptoms such as ataxia, tremor, and fine motor dysfunction. The objective was to investigate the cerebellar damage caused by an acute galactose administration. Thirty-day-old male and female Wistar rats were used.

Spatiotemporal imaging of nonlinear optics in van der Waals waveguides.

Van der Waals (vdW) semiconductors have emerged as promising platforms for efficient nonlinear optical conversion, including harmonic and entangled photon generation. Although major efforts are devoted to integrating vdW materials in nanoscale waveguides for miniaturization, the realization of efficient, phase-matched conversion in these platforms remains challenging. Here, to address this challenge, we report a far-field ultrafast imaging method to track the propagation of both fundamental and harmonic waves within vdW waveguides with femtosecond and sub-50 nanometre spatiotemporal precision.

Infrared nanosensors of piconewton to micronewton forces.

Mechanical force is an essential feature for many physical and biological processes, and remote measurement of mechanical signals with high sensitivity and spatial resolution is needed for diverse applications, including robotics, biophysics, energy storage and medicine. Nanoscale luminescent force sensors excel at measuring piconewton forces, whereas larger sensors have proven powerful in probing micronewton forces. However, large gaps remain in the force magnitudes that can be probed remotely from subsurface or interfacial sites, and no individual, non-invasive sensor is capable of measuring over the large dynamic range needed to understand many systems.

Aggregation pathway complexity in a simple perylene diimide.

This study characterizes the influence of self-assembly conditions on the aggregation pathway and resulting photophysical properties of one-dimensional aggregates of the simple imide-substituted perylene diimide, N, N'-didodecyl-3,4,9,10-perylenedicarboximide (ddPDI). We show that ddPDI, which has symmetric alkyl chains at the imide positions, assembles into fibers with distinct morphology, emission spectra, and temperature-dependent behavior as a function of preparation conditions. In all conditions explored, aggregates are one-dimensional; however, assembly conditions can bias formation to either J-like or H-like aggregates.

Advances in the photon avalanche luminescence of inorganic lanthanide-doped nanomaterials.

Photon avalanche (PA)-where the absorption of a single photon initiates a 'chain reaction' of additional absorption and energy transfer events within a material-is a highly nonlinear optical process that results in upconverted light emission with an exceptionally steep dependence on the illumination intensity. Over 40 years following the first demonstration of photon avalanche emission in lanthanide-doped bulk crystals, PA emission has been achieved in nanometer-scale colloidal particles. The scaling of PA to nanomaterials has resulted in significant and rapid advances, such as luminescence imaging beyond the diffraction limit of light, optical thermometry and force sensing with (sub)micron spatial resolution, and all-optical data storage and processing.

Progerin can induce DNA damage in the absence of global changes in replication or cell proliferation.

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic condition characterized by features of accelerated aging, and individuals with HGPS seldom live beyond their mid-teens. The syndrome is commonly caused by a point mutation in the LMNA gene which codes for lamin A and its splice variant lamin C, components of the nuclear lamina. The mutation causing HGPS leads to production of a truncated, farnesylated form of lamin A referred to as "progerin.

Width-dependent continuous growth of atomically thin quantum nanoribbons from nanoalloy seeds in chalcogen vapor.

Nanoribbons (NRs) of atomic layer transition metal dichalcogenides (TMDs) can boost the rapidly emerging field of quantum materials owing to their width-dependent phases and electronic properties. However, the controllable downscaling of width by direct growth and the underlying mechanism remain elusive. Here, we demonstrate the vapor-liquid-solid growth of single crystal of single layer NRs of a series of TMDs (MeX: Me = Mo, W; X = S, Se) under chalcogen vapor atmosphere, seeded by pre-deposited and respective transition metal-alloyed nanoparticles that also control the NR width.

Increased Formation of Trions and Charged Biexcitons by Above-Gap Excitation in Single-layer WSe.

Two-dimensional semiconductors exhibit pronounced many-body effects and intense optical responses due to strong Coulombic interactions. Consequently, subtle differences in photoexcitation conditions can strongly influence how the material dissipates energy during thermalization. Here, using multiple excitation spectroscopies, we show that a distinct thermalization pathway emerges at elevated excitation energies, enhancing the formation of trions and charged biexcitons in single-layer WSe by up to 2× and 5× , respectively.

Short-Wave Infrared Upconverting Nanoparticles.

Optical technologies enable real-time, noninvasive analysis of complex systems but are limited to discrete regions of the optical spectrum. While wavelengths in the short-wave infrared (SWIR) window (typically, 1700-3000 nm) should enable deep subsurface penetration and reduced photodamage, there are few luminescent probes that can be excited in this region. Here, we report the discovery of lanthanide-based upconverting nanoparticles (UCNPs) that efficiently convert 1740 or 1950 nm excitation to wavelengths compatible with conventional silicon detectors.

Reproducibility of [F]MK-6240 kinetics in brain studies with shortened dynamic PET protocol in healthy/cognitively normal subjects.

Background: [F]MK-6240 is a neurofibrillary tangles PET radiotracer that has been broadly used in aging and Alzheimer's disease (AD) studies. Majority of [F]MK-6240 PET studies use dynamic acquisitions longer than 60 min to assess the tracer kinetic parameters. As of today, no consensus has been established on the optimum dynamic PET scan time.

Flotation Coefficient Distributions of Lipid Nanoparticles by Sedimentation Velocity Analytical Ultracentrifugation.

The robust characterization of lipid nanoparticles (LNPs) encapsulating therapeutics or vaccines is an important and multifaceted translational problem. Sedimentation velocity analytical ultracentrifugation (SV-AUC) has proven to be a powerful approach in the characterization of size-distribution, interactions, and composition of various types of nanoparticles across a large size range, including metal nanoparticles (NPs), polymeric NPs, and also nucleic acid loaded viral capsids. Similar potential of SV-AUC can be expected for the characterization of LNPs, but is hindered by the flotation of LNPs being incompatible with common sedimentation analysis models.

Modulation of biophysical properties of nucleocapsid protein in the mutant spectrum of SARS-CoV-2.

Genetic diversity is a hallmark of RNA viruses and the basis for their evolutionary success. Taking advantage of the uniquely large genomic database of SARS-CoV-2, we examine the impact of mutations across the spectrum of viable amino acid sequences on the biophysical phenotypes of the highly expressed and multifunctional nucleocapsid protein. We find variation in the physicochemical parameters of its extended intrinsically disordered regions (IDRs) sufficient to allow local plasticity, but also observe functional constraints that similarly occur in related coronaviruses.

Human CST Stimulates Base Excision Repair to Prevent the Accumulation of Oxidative DNA Damage.

CTC1-STN1-TEN1 (CST) is a single-stranded DNA binding protein vital for telomere length maintenance with additional genome-wide roles in DNA replication and repair. While CST was previously shown to function in double-strand break repair and promote replication restart, it is currently unclear whether it has specialized roles in other DNA repair pathways. Proper and efficient repair of DNA is critical to protecting genome integrity.

Assembly of SARS-CoV-2 nucleocapsid protein with nucleic acid.

The viral genome of SARS-CoV-2 is packaged by the nucleocapsid (N-)protein into ribonucleoprotein particles (RNPs), 38 ± 10 of which are contained in each virion. Their architecture has remained unclear due to the pleomorphism of RNPs, the high flexibility of N-protein intrinsically disordered regions, and highly multivalent interactions between viral RNA and N-protein binding sites in both N-terminal (NTD) and C-terminal domain (CTD). Here we explore critical interaction motifs of RNPs by applying a combination of biophysical techniques to ancestral and mutant proteins binding different nucleic acids in an in vitro assay for RNP formation, and by examining nucleocapsid protein variants in a viral assembly assay.

Ligand-Assisted Direct Lithography of Upconverting and Avalanching Nanoparticles for Nonlinear Photonics.

Upconverting nanoparticles (UCNPs) exhibit unique nonlinear optical properties that can be harnessed in microscopy, sensing, and photonics. However, forming high-resolution nano- and micropatterns of UCNPs with large packing fractions is still challenging. Additionally, there is limited understanding of how nanoparticle patterning chemistries are affected by the particle size.

Evaluation of Non-Invasive Methods for (R)-[C]PK11195 PET Image Quantification in Multiple Sclerosis.

This study aims to evaluate non-invasive PET quantification methods for (R)-[C]PK11195 uptake measurement in multiple sclerosis (MS) patients and healthy controls (HC) in comparison with arterial input function (AIF) using dynamic (R)-[C]PK11195 PET and magnetic resonance images. The total volume of distribution (VT) and distribution volume ratio (DVR) were measured in the gray matter, white matter, caudate nucleus, putamen, pallidum, thalamus, cerebellum, and brainstem using AIF, the image-derived input function (IDIF) from the carotid arteries, and pseudo-reference regions from supervised clustering analysis (SVCA). Uptake differences between MS and HC groups were tested using statistical tests adjusted for age and sex, and correlations between the results from the different quantification methods were also analyzed.

Programmable nanowrinkle-induced room-temperature exciton localization in monolayer WSe.

Localized states in two-dimensional (2D) transition metal dichalcogenides (TMDCs) have been the subject of intense study, driven by potential applications in quantum information science. Despite the rapidly growing knowledge surrounding these emitters, their microscopic nature is still not fully understood, limiting their production and application. Motivated by this challenge, and by recent theoretical and experimental evidence showing that nanowrinkles generate strain-localized room-temperature emitters, we demonstrate a method to intentionally induce wrinkles with collections of stressors, showing that long-range wrinkle direction and position are controllable with patterned array design.

Accelerated Nano-Optical Imaging through Sparse Sampling.

The integration time and signal-to-noise ratio are inextricably linked when performing scanning probe microscopy based on raster scanning. This often yields a large lower bound on the measurement time, for example, in nano-optical imaging experiments performed using a scanning near-field optical microscope (SNOM). Here, we utilize sparse scanning augmented with Gaussian process regression to bypass the time constraint.

Dynamics of self-hybridized exciton-polaritons in 2D halide perovskites.

Excitons, bound electron-hole pairs, in two-dimensional hybrid organic inorganic perovskites (2D HOIPs) are capable of forming hybrid light-matter states known as exciton-polaritons (E-Ps) when the excitonic medium is confined in an optical cavity. In the case of 2D HOIPs, they can self-hybridize into E-Ps at specific thicknesses of the HOIP crystals that form a resonant optical cavity with the excitons. However, the fundamental properties of these self-hybridized E-Ps in 2D HOIPs, including their role in ultrafast energy and/or charge transfer at interfaces, remain unclear.

Dual Effect of Carnosine on ROS Formation in Rat Cultured Cortical Astrocytes.

Carnosine is composed of β-alanine and L-histidine and is considered to be an important neuroprotective agent with antioxidant, metal chelating, and antisenescence properties. However, children with serum carnosinase deficiency present increased circulating carnosine and severe neurological symptoms. We here investigated the in vitro effects of carnosine on redox and mitochondrial parameters in cultured cortical astrocytes from neonatal rats.