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Drug discovery relies on efficient identification of small-molecule leads and their interactions with macromolecular targets. However, understanding how chemotypes impact mechanistically important conformational states often remains secondary among high-throughput discovery methods. Here, we present a conformational discovery pipeline integrating time-resolved, high-throughput small-angle X-ray scattering (TR-HT-SAXS) and classic fragment screening applied to allosteric states of the mitochondrial import oxidoreductase apoptosis-inducing factor (AIF). By monitoring oxidized and X-ray-reduced AIF states, TR-HT-SAXS leverages structure and kinetics to generate a multidimensional screening dataset that identifies fragment chemotypes allosterically stimulating AIF dimerization. Fragment-induced dimerization rates, quantified with time-resolved SAXS similarity analysis (kVR), capture structure-activity relationships (SAR) across the top-ranked 4-aminoquinoline chemotype. Crystallized AIF-aminoquinoline complexes validate TR-SAXS-guided SAR, supporting this conformational chemotype for optimization. AIF-aminoquinoline structures and mutational analysis reveal active site F482 as an underappreciated allosteric stabilizer of AIF dimerization. This conformational discovery pipeline illustrates TR-HT-SAXS as an effective technology for targeting chemical leads to important macromolecular states.

Highly concentrated aqueous electrolytes (termed water-in-salt electrolytes, WiSEs) at solid-liquid interfaces are ubiquitous in myriad applications including biological signaling, electrosynthesis, and energy storage. This interface, known as the electrical double layer (EDL), has a different structure in WiSEs than in dilute electrolytes. Here, we investigate how divalent salts [zinc bis(trifluoromethylsulfonyl)imide, Zn(TFSI)2], as well as mixtures of mono- and divalent salts [lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) mixed with Zn(TFSI)2], affect the short- and long-range structure of the EDL under confinement using a multimodal combination of scattering, spectroscopy, and surface forces measurements. Raman spectroscopy of bulk electrolytes suggests that the cation is closely associated with the anion regardless of valency. Wide-angle X-ray scattering reveals that all bulk electrolytes form ion clusters; however, the clusters are suppressed with increasing concentration of the divalent ion. To probe the EDL under confinement, we use a Surface Forces Apparatus and demonstrate that the thickness of the adsorbed layer of ions at the interface grows with increasing divalent ion concentration. Multiple interfacial layers form following this adlayer; their thicknesses appear dependent on anion size, rather than cation. Importantly, all electrolytes exhibit very long electrostatic decay lengths that are insensitive to valency. It is likely that in the WiSE regime, electrostatic screening is mediated by the formation of ion clusters rather than individual well-solvated ions. This work contributes to understanding the structure and charge-neutralization mechanism in this class of electrolytes and the interfacial behavior of mixed-electrolyte systems encountered in electrochemistry and biology.

The molecular foundations of epidermal cell wall mechanics are critical for understanding structure-function relationships of primary cell walls in plants and facilitating the design of bioinspired materials. To uncover the molecular mechanisms regulating the high extensibility and strength of the cell wall, the onion epidermal wall is stretched uniaxially to various strains and cell wall structures from mesoscale to atomic scale are characterized. Upon longitudinal stretching to high strain, epidermal walls contract in the transverse direction, resulting in a reduced area. Atomic force microscopy shows that cellulose microfibrils exhibit orientation-dependent rearrangements at high strains: longitudinal microfibrils are straightened out and become highly ordered, while transverse microfibrils curve and kink. Small-angle X-ray scattering detects a 7.4 nm spacing aligned along the stretch direction at high strain, which is attributed to distances between individual cellulose microfibrils. Furthermore, wide-angle X-ray scattering reveals a widening of (004) lattice spacing and contraction of (200) lattice spacing in longitudinally aligned cellulose microfibrils at high strain, which implies longitudinal stretching of the cellulose crystal. These findings provide molecular insights into the ability of the wall to bear additional load after yielding: the aggregation of longitudinal microfibrils impedes sliding and enables further stretching of the cellulose to bear increased loads.

In this article we investigate novel signatures of radiation reaction via the angular deflection of an electron beam colliding at 90 degrees with an intense laser pulse. Due to the radiation reaction effect, the electrons can be deflected towards the beam axis for plane wave backgrounds, which is not possible in the absence of radiation reaction effects. The magnitude and size of the deflection angle can be controlled by tailoring the laser pulse shapes. The effect is first derived analytically using the Landau-Lifshitz equation, which allows to determine the important scaling behavior with laser intensity and particle energy. We then move on to full scale 3D Monte Carlo simulations to verify the effect is observable with present day laser technology. We investigate the opportunities for an indirect observation of laser depletion in such side scattering scenarios.

The axon-initial-segment (AIS) of mature neurons contains microtubule (MT) fascicles (linear bundles) implicated as retrograde diffusion barriers in the retention of MT-associated protein (MAP) tau inside axons. Tau dysfunction and leakage outside of the axon is associated with neurodegeneration. We report on the structure of steady-state MT bundles in varying concentrations of Mg2+ or Ca2+ divalent cations in mixtures containing αβ-tubulin, full-length tau, and GTP at 37 °C in a physiological buffer. A concentration-time kinetic phase diagram generated by synchrotron SAXS reveals a wide-spacing MT bundle phase (Bws), a transient intermediate MT bundle phase (Bint), and a tubulin ring phase. SAXS with TEM of plastic-embedded samples provides evidence of a viscoelastic intervening network (IN) of complexes of tubulin oligomers and tau stabilizing MT bundles. In this model, αβ-tubulin oligomers in the IN are crosslinked by taus MT binding repeats, which also link αβ-tubulin oligomers to αβ-tubulin within the MT lattice. The model challenges whether the cross-bridging of MTs is attributed entirely to MAPs. Tubulin-tau complexes in the IN or bound to isolated MTs are potential sites for enzymatic modification of tau, promoting nucleation and growth of tau fibrils in tauopathies.

Electron bifurcation (BF) is an evolutionarily ancient energy coupling mechanism in anaerobes, whose associated enzymatic machinery remains enigmatic. In BF-flavoenzymes, a chemically high-potential electron forms in a thermodynamically favorable fashion by simultaneously dropping the potential of a second electron before its donation to physiological acceptors. The cryo-EM and spectroscopic analyses of the BF-enzyme Fix/EtfABCX from Thermotoga maritima suggest that the BF-site contains a special flavin-adenine dinucleotide and, upon its reduction with NADH, a low-potential electron transfers to ferredoxin and a high-potential electron reduces menaquinone. The transfer of energy from high-energy intermediates must be carefully orchestrated conformationally to avoid equilibration. Herein, anaerobic size exclusion-coupled small-angle X-ray scattering (SEC-SAXS) shows that the Fix/EtfAB heterodimer subcomplex, which houses BF- and electron transfer (ET)-flavins, exists in a conformational equilibrium of compacted and extended states between flavin-binding domains, the abundance of which is impacted by reduction and NAD(H) binding. The conformations identify dynamics associated with the T. maritima enzyme and also recapitulate states identified in static structures of homologous BF-flavoenzymes. Reduction of Fix/EtfABCX's flavins alone is insufficient to elicit domain movements conducive to ET but requires a structural "trigger" induced by NAD(H) binding. Models show that Fix/EtfABCX's superdimer exists in a combination of states with respect to its BF-subcomplexes, suggesting a cooperative mechanism between supermonomers for optimizing catalysis. The correlation of conformational states with pathway steps suggests a structural means with which Fix/EtfABCX may progress through its catalytic cycle. Collectively, these observations provide a structural framework for tracing Fix/EtfABCX's catalysis.

We consider a Schrödinger equation with a nonlinearity which is a general perturbation of a power nonlinearity. We construct a profile decomposition adapted to this nonlinearity. We also prove global existence and scattering in a general defocusing setting, assuming that the critical Sobolev norm is bounded in the energy-supercritical case. This generalizes several previous works on double-power nonlinearities. [ABSTRACT FROM AUTHOR]

We investigate the terahertz (THz) scattering and emission properties of lunar regolith by modeling it as a random medium with rough top and bottom boundaries and a host medium situated beneath. The total scattering and emission arise from three sources: the rough boundaries, the volume, and the interactions between the boundaries and the volume. To account for these sources, we model their respective phase matrices and apply the matrix doubling approach to couple these phase matrices to compute the total emission. The model is then used to explore insights into lunar regolith scattering and emission processes. The simulations reveal that surface roughness is the primary contributor to total scattering, while dielectric contrasts between the volume and the boundaries dominate total emission. The THz emissivity is highly sensitive to the regolith dielectric constant, particularly its imaginary part, making it a promising alternative for identifying previously undetected water ice in the lunar polar regions. The THz emissivity model developed in this study can be readily applied to invert the surface parameters of lunar regolith using THz observations. [ABSTRACT FROM AUTHOR]

The role of various light scattering phenomena in aesthetics and clinical practice is explored in this review. Four main types of light scattering, Tyndall, Rayleigh, Mie, and Raman, are discussed. Each type is explained in terms of its physical principles and its applications in aesthetic medicine. Tyndall scattering is relevant in understanding the blue appearance of certain dermal fillers. Rayleigh scattering contributes to skin tone perception and plays a role in certain laser treatments. Mie scattering is important in laser hair removal and the appearance of skin conditions like melasma. Raman scattering, while primarily used in research, shows promise for non‐invasive skin analysis, personalized skincare, treatment monitoring, and early skin cancer detection. It is important to understand these scattering phenomena for optimizing light‐based aesthetic procedures and developing effective treatments. Properly applying the appropriate scattering theory based on relative particle size is crucial in clinical aesthetic practice. [ABSTRACT FROM AUTHOR]

This study investigates terahertz (THz) wave scattering from a simulated lunar regolith surface, with a focus on the Brewster feature, backscattering, and bistatic scattering within the 325 to 500 GHz range. We employed a generalized power-law spectrum to characterize surface roughness and fabricated Gaussian correlated surfaces from Durable Resin V2 using 3D printing technology. The complex dielectric permittivity of these materials was determined through THz time-domain spectroscopy (THz-TDS). Our experimental setup comprised a vector network analyzer (VNA) equipped with dual waveguide frequency extenders for the WR-2.2 band, transmitter and receiver modules, polarizing components, and a scattering chamber. We systematically analyzed the effects of root-mean-square (RMS) height, correlation length, dielectric constant, frequency, polarization, and observation angle on THz scattering. The findings highlight the significant impact of surface roughness on the Brewster angle shift, backscattering, and bistatic scattering. These insights are crucial for refining theoretical models and developing algorithms to retrieve physical parameters for lunar and other celestial explorations. [ABSTRACT FROM AUTHOR]

Attributed scattering problems have been found to be helpful in inverse synthetic aperture radar (ISAR) imaging and target recognition problems. In this model, the scattering centres are divided into two categories: localised and distributed. Localised scattering centres are those that are concentrated in a small area, while distributed scattering centres are spread out over a larger area. Several methods have been proposed to estimate the scattering centres which aim to accurately identify the location and characteristics of the scattering centres. However, detecting a distributed scattering centre remains a challenging task. A novel technique is proposed based on sparse signals to improve the detection of distributed scattering centres from localised ones. This technique takes advantage of the sparsity of the signals to accurately identify the location of the distributed scattering centres. Experimental results demonstrate the superiority of algorithm in detecting distributed scattering centres. This improved detection capability has significant implications for ISAR imaging and target recognition problems. [ABSTRACT FROM AUTHOR]

The current study investigates the effects of strong potential porous materials to absorb the transmitted energy in a dissipative device containing a wave-bearing cavity. The expansion chamber consists of horizontal as well as vertical elastic boundaries that is filled with a compressible fluid and porous media. The porous media is dealt as an equivalent fluid with complex propagation speed and density, has effects on the eigenfunctions of cavity regions. The vibrational response of the vertical elastic components having different sets of edge conditions are incorporated by mode-matching tailored-Galerkin (MMTG) approach. This approach provides displacement of vertical elastic membrane which deals with various edge conditions. The MMTG approach has point-wise convergence that is conform through generalized orthogonal relations. The MMTG solutions are used to reconstruct matching conditions and to satisfy law of conservation of energy. It confirms the validity of retained solutions and accuracy of performed algebra. It is observed from the curves of TL and P abs that by varying edge conditions the absorbed power and TL are enhanced. [ABSTRACT FROM AUTHOR]

The diverse Lyman-alpha (Ly  |$\alpha$|⁠) line profiles are essential probes of gas in and around galaxies. While isotropic models can successfully reproduce a range of  Ly  |$\alpha$| observables, the correspondence between the model and actual physical parameters remains uncertain. We investigate the effect of anisotropies on Ly  |$\alpha$| escape using a simplified setup: an empty hole (fractional size |$\tilde{s}$|⁠) within a semi-infinite slab with constant column density. Due to the slab's high line-centre optical depth (⁠|$\tau _0\gtrsim 10^{5-6}$|⁠), most photons should escape through the empty channel. However, our numerical findings indicate that only a fraction |${\sim} \tilde{s}$| of photons exit through this channel. To explain this puzzle, we developed an analytical model describing the scattering and transmission behaviour of  Ly  |$\alpha$| photons in an externally illuminated slab. Our findings show that the number of scatterings per reflection follows a Lévy distribution (⁠|${\propto} N^{-3/2}$|⁠). This means that the mean number of scatterings is orders of magnitude greater than expectations, facilitating a shift in frequency and the subsequent photon escape. Our results imply that  Ly  |$\alpha$| photons are more prone to traverse high-density gas and are surprisingly less biased to the 'path of least resistance'. Hence,  Ly  |$\alpha$| can trace an average hydrogen distribution rather than only low-column density channels. [ABSTRACT FROM AUTHOR]

This work studies a coupled non-linear Schrödinger system with a singular source term. First, we investigate the question of the local existence of solutions. Second, one proves the existence of global solutions which scatter in some Sobolev spaces. Finally, one establishes the existence of non-global solutions. The main difficulty here is to overcome the regularity problem in the non-linearity. Indeed, because of the singularity of the source term, the classical contraction method in the energy space fails in such a regime. So, this paper is to fill such a gap in the literature. The argument follows ideas in T. Cazenave and I. Naumkin (Comm. Contemp. Math. , 19 (2017), 1650038). This consists to remark that the singularity problem is only near the origin. So, one needs to impose that the solution stays away from zero. This is not trivial, since there is no maximum principle for the Schrödinger equation. The existence of global solutions which scatter follows with the pseudo-conformal transformation via the existence of local solutions. Finally, the existence of non-global solutions follows with the classical variance method. [ABSTRACT FROM AUTHOR]

This research introduces an innovative application of physics-informed neural networks (PINNs) to tackle the intricate challenges of radiative transfer (RT) modelling in exoplanetary atmospheres, with a special focus on efficiently handling scattering phenomena. Traditional RT models often simplify scattering as absorption, leading to inaccuracies. Our approach utilizes PINNs, noted for their ability to incorporate the governing differential equations of RT directly into their loss function, thus offering a more precise yet potentially fast modelling technique. The core of our method involves the development of a parametrized PINN tailored for a modified RT equation, enhancing its adaptability to various atmospheric scenarios. We focus on RT in transiting exoplanet atmospheres using a simplified 1D isothermal model with pressure-dependent coefficients for absorption and Rayleigh scattering. In scenarios of pure absorption, the PINN demonstrates its effectiveness in predicting transmission spectra for diverse absorption profiles. For Rayleigh scattering, the network successfully computes the RT equation, addressing both direct and diffuse stellar light components. While our preliminary results with simplified models are promising, indicating the potential of PINNs in improving RT calculations, we acknowledge the errors stemming from our approximations as well as the challenges in applying this technique to more complex atmospheric conditions. Specifically, extending our approach to atmospheres with intricate temperature-pressure profiles and varying scattering properties, such as those introduced by clouds and hazes, remains a significant area for future development. [ABSTRACT FROM AUTHOR]

Light from ground-based sources directed into the upper hemisphere can be partially controlled, for example, through suitable lamp shades or by reducing the number of luminaires and their lumen output. However, ground-reflected radiation is pervasive in artificially lit urban environments and cannot be entirely avoided. This component of upward-directed light is typically modelled using Lambertian diffuse reflection. Here, we demonstrate that the current analytical models for ground-reflected radiation can be improved by incorporating additional components, such as reflections from vertically oriented surfaces and vegetation. Our findings indicate that near edges of cities, the contribution of the reflected radiation to the overall skyglow is slightly higher than recent models predict. However, at medium-to-long distances the skyglow increases by 50–200 per cent compared to what these models suggest. This is because non-horizontal surfaces reflect more light towards small angles above the horizontal, contrasting with the outcomes predicted by the basic Lambertian framework. Consequently, light escaping from ground-based sources can propagate more effectively over longer distances, even when there is a complete cutoff of light emitted from luminaires in the upper half-space. These findings have significant implications for skyglow modelling. Furthermore, it also limits the available options for implementing measures to reduce skyglow levels at astronomical observatories located well beyond city boundaries. [ABSTRACT FROM AUTHOR]

In this study, we use the UK Molecular r-matrix (ukrmol) codes in the close-coupling approximation to examine the photoionization of hydrogen halides (hydrogen fluoride, hydrogen chloride, and hydrogen bromide). This article reports the total and partial photoionization cross-sections for the |$\mathrm{X}^2 \Pi$|⁠ , |$\mathrm{A}^2 \Sigma ^{+}$|⁠ , and |$\mathrm{B}^2 \Sigma ^{+}$| ionic states of these halides. The calculated cross-sections are compared with the available literature, which does not accurately represent the effective cross-sections near the threshold region, which is dominated by the Rydberg series autoionization resonances converging to the |$\mathrm{A}^2 \Sigma ^{+}$| ionic state. There seems to have been minimal effort to investigate the Rydberg-bound states of these halides. Meanwhile, the r-matrix approaches have traditionally excelled at characterizing such studies. This indicates the effectiveness of this method for molecular photoionization as well as for understanding the resonant contribution to the photoionization cross-sections. The detailed cross-sections calculated comprise the complex autoionizing resonance structures capable of significantly contributing to the computations of total photoionization rates, which are necessary to maintain a steady state of ionization in astrophysical plasmas. Comparisons with the experimental measurements and the theoretical data generally show reasonable agreement across the reported energy range. [ABSTRACT FROM AUTHOR]

Significance: Although spatial frequency domain imaging (SFDI) has been well characterized under diffuse optical conditions, tissue measurements made outside the diffuse regime can provide new diagnostic information. Before such measurements can become clinically relevant, however, the behavior of sub-diffuse SFDI and its effect on the accuracy of derived tissue parameters must be assessed. Aim: We aim to characterize the impact that both the assumed scattering phase function (SPF) and the polarization state of the illumination light source have on the accuracy of SFDI-derived optical properties when operating under diffuse or subdiffuse conditions, respectively. Approach: Through the use of a set of well-characterized optical phantoms, SFDI accuracy was assessed at four wavelengths (395, 545, 625, and 850 nm) and two different spatial frequencies (0.3 and 1.0 mm-1), which provided a broad range of diffuse and sub-diffuse conditions, using three different SPFs. To determine the effects of polarization, the SFDI accuracy was assessed using both unpolarized and cross-polarized illumination. Results: It was found that the assumed SPF has a direct and significant impact on the accuracy of the SFDI-derived optical properties, with the best choice of SPF being dictated by the polarization state. As unpolarized SFDI retains the sub-diffuse portion of the signal, optical properties were found to be more accurate when using the full SPF that includes forward and backscattering components. By contrast, cross-polarized SFDI yielded accurate optical properties when using a forward-scattering SPF, matching the behavior of cross-polarization to attenuate the immediate backscattering of sub-diffuse reflectance. Using the correct pairings of SPF and polarization enabled using a reflectance standard, instead of a more subjective phantom, as the reference measurement. Conclusions: These results provide the foundation for a more thorough understanding of SFDI and enable new applications of this technology in which sub-diffuse conditions dominate (e.g., μa/&#956's) or high spatial frequencies are required. [ABSTRACT FROM AUTHOR]

Ultrasound B-scan images are traditionally formed from the envelope of the received radiofrequency echoes, but the image texture is dominated by granular speckle patterns. Longstanding efforts at speckle reduction and deconvolution have been developed to lessen the detrimental aspects of speckle. However, we now propose an alternative approach to estimation (and image rendering) of the underlying fine grain scattering density of tissues based on power law constraints. The key steps are a whitening of the spectrum of the received signal while conforming to the original envelope shape and statistics, followed by a power law filtering in accordance with the known scattering behavior of tissues. This multiple step approach results in a high-spatial-resolution map of scattering density that is constrained by the most important properties of scattering from tissues. Examples from in vivo liver scans are shown to illustrate the change in image properties from this framework. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of research conducted on the Method of Auxiliary Sources (MAS) over a period of the last 22 years, i.e., since the last up-to-date survey was published. MAS is a very attractive numerical technique due to its simple algorithmic structure and the generally low computational cost it requires in terms of memory and CPU time; this is why it has been applied to a vast variety of cases, as concluded by the long citations list included. After a short introduction summarizing the fundamental concepts of the method, references since 2002 are categorized, briefly described, and commented on. This work is intended to assist every researcher who is involved in MAS computations, providing an exhaustive, to the best of the authors' knowledge, list of related publications. [ABSTRACT FROM AUTHOR]

In this work we present a formalism based on scalar Green's functions to deal with electromagnetic scattering problems. Although the formulations of the Mie theory and Born approximations in terms of electromagnetic scattering are well known and relevant, they have certain disadvantages: complexity, computational time, few symmetries, etc. Therefore, the study with scalar Green's functions allows dealing with these problems with greater simplicity and efficiency. However, the information provided by the vector formulation is sacrificed. Nevertheless, different cases of electromagnetic scattering of dielectric media with different dimensions, geometries and refractive indices will be presented. Thus, we will be able to verify the capacity of this scalar method in predicting light-scattering problems. [ABSTRACT FROM AUTHOR]

In this paper, the Cauchy problem for a class of coupled system of the four-dimensional cubic focusing nonlinear Schrödinger equations was investigated. By exploiting the double Duhamel method and the long-time Strichartz estimate, the global well-posedness and scattering were proven for the system below the ground state. In our proof, we first established the variational characterization of the ground state, and obtained the threshold of the global well-posedness and scattering. Second, we showed that the non-scattering is equivalent to the existence of an almost periodic solution by following the concentration-compactness/rigidity arguments of Kenig and Merle [17] (Invent. Math., 166 (2006), 645–675). Then, we obtained the global well-posedness and scattering below the threshold by excluding the almost periodic solution. [ABSTRACT FROM AUTHOR]

Germanium (Ge) is a system-forming material of IR photonics for the atmospheric transparency window of 8–14 µm. For optics of the 3–5 µm range, more widespread silicon (Si), which has phonon absorption bands in the long-wave region, is predominantly used. A technology for growing Ge single crystals has been developed, allowing the production of precision optical parts up to 500 mm in diameter. Ge is used primarily for the production of transparent optical parts for thermal imaging devices in the 8–14 µm range. In addition, germanium components are widely used in a large number of optical devices where such properties as mechanical strength, good thermal properties, and climatic resistance are required. A very important area of application of germanium is nonlinear optics, primarily acousto-optics. The influence of doping impurities and temperature on the absorption of IR radiation in germanium is considered in detail. The properties of germanium photodetectors are reported, primarily on the effect of photon drag of holes. Optical properties in the THz range are considered. The features of optical properties for all five stable isotopes of germanium are studied. The isotopic shift of absorption bands in the IR region, caused by phonon phenomena, which was discovered by the authors for the first time, is considered. [ABSTRACT FROM AUTHOR]

Abstract Attributed scattering problems have been found to be helpful in inverse synthetic aperture radar (ISAR) imaging and target recognition problems. In this model, the scattering centres are divided into two categories: localised and distributed. Localised scattering centres are those that are concentrated in a small area, while distributed scattering centres are spread out over a larger area. Several methods have been proposed to estimate the scattering centres which aim to accurately identify the location and characteristics of the scattering centres. However, detecting a distributed scattering centre remains a challenging task. A novel technique is proposed based on sparse signals to improve the detection of distributed scattering centres from localised ones. This technique takes advantage of the sparsity of the signals to accurately identify the location of the distributed scattering centres. Experimental results demonstrate the superiority of algorithm in detecting distributed scattering centres. This improved detection capability has significant implications for ISAR imaging and target recognition problems.

This study explored the time asymptotic behavior of the Schrödinger equation with an inhomogeneous energy-critical nonlinearity. The approach follows the concentration-compactness method due to Kenig and Merle. To address the primary challenge posed by the singular inhomogeneous term, we utilized Caffarelli-Kohn-Nirenberg weighted inequalities. This work notably expanded the existing literature by applying these techniques to higher spatial dimensions without requiring any spherically symmetric assumption.

This work studies a coupled non-linear Schrödinger system with a singular source term. First, we investigate the question of the local existence of solutions. Second, one proves the existence of global solutions which scatter in some Sobolev spaces. Finally, one establishes the existence of non-global solutions. The main difficulty here is to overcome the regularity problem in the non-linearity. Indeed, because of the singularity of the source term, the classical contraction method in the energy space fails in such a regime. So, this paper is to fill such a gap in the literature. The argument follows ideas in T. Cazenave and I. Naumkin (Comm. Contemp. Math., 19 (2017), 1650038). This consists to remark that the singularity problem is only near the origin. So, one needs to impose that the solution stays away from zero. This is not trivial, since there is no maximum principle for the Schrödinger equation. The existence of global solutions which scatter follows with the pseudo-conformal transformation via the existence of local solutions. Finally, the existence of non-global solutions follows with the classical variance method.

The interdomain electron transfer (IET) between the catalytic flavodehydrogenase domain and the electron-transferring cytochrome domain of cellobiose dehydrogenase (CDH) plays an essential role in biocatalysis, biosensors and biofuel cells, as well as in its natural function as an auxiliary enzyme of lytic polysaccharide monooxygenase. We investigated the mobility of the cytochrome and dehydrogenase domains of CDH, which is hypothesised to limit IET in solution by small angle X-ray scattering (SAXS). CDH from Myriococcum thermophilum (syn. Crassicarpon hotsonii, syn. Thermothelomyces myriococcoides) was probed by SAXS to study the CDH mobility at different pH and in the presence of divalent cations. By comparison of the experimental SAXS data, using pair-distance distribution functions and Kratky plots, we show an increase in CDH mobility at higher pH, indicating alterations of domain mobility. To further visualise CDH movement in solution, we performed SAXS-based multistate modelling. Glycan structures present on CDH partially masked the resulting SAXS shapes, we diminished these effects by deglycosylation and studied the effect of glycoforms by modelling. The modelling shows that with increasing pH, the cytochrome domain adopts a more flexible state with significant separation from the dehydrogenase domain. On the contrary, the presence of calcium ions decreases the mobility of the cytochrome domain. Experimental SAXS data, multistate modelling and previously reported kinetic data show how pH and divalent ions impact the closed state necessary for the IET governed by the movement of the CDH cytochrome domain.

Nano-scale dynamics of self-assembled therapeutics play a large role in their biological function. However, assessment of such dynamics remains absent from conventional pharmaceutical characterization. We hypothesize that time-resolved small-angle neutron scattering (TR-SANS) can reveal their kinetic properties. For lipid nanoparticles (LNP), limited molecular motion is important for avoiding degradation prior to entering cells while, intracellularly, enhanced molecular motion is then vital for effective endosomal escape. We propose TR-SANS for quantifying molecular exchange in LNPs and, therefore, enabling optimization of opposing molecular behaviors of a pharmaceutical in two distinct environments. We use TR-SANS in combination with traditional SANS and small-angle x-ray scattering (SAXS) to experimentally quantify nano-scale dynamics and provided unprecedented insight to molecular behavior of LNPs. LNPs have molecular exchange dynamics relevant to storage and delivery which can be captured using TR-SANS. Cholesterol exchanges on the time-scale of hours even at neutral pH. As pH drops below the effective pKa of the ionizable lipid, molecular exchange occurs faster. The results give insight into behavior enabling delivery and provide a quantifiable metric by which to compare formulations. Successful analysis of this multi-component system also expands the opportunities for using TR-SANS to characterize complex therapeutics.   [ABSTRACT FROM AUTHOR]

We consider the L 2 -supercritical nonlinear Schrödinger equation with a repulsive Dirac delta potential in one dimensional space. In a previous work, we clarified the global dynamics of even solutions with the same action as the high-frequency ground state standing wave solutions. In that case, there are obvious non-scattering global solutions, i.e., the standing waves. In this paper, we show a scattering and blow-up dichotomy for threshold even solutions in the low-frequency case. We emphasize that this dichotomy still holds at the critical frequency between high and low. [ABSTRACT FROM AUTHOR]

Ultrasound B-scan images are traditionally formed from the envelope of the received radiofrequency echoes, but the image texture is dominated by granular speckle patterns. Longstanding efforts at speckle reduction and deconvolution have been developed to lessen the detrimental aspects of speckle. However, we now propose an alternative approach to estimation (and image rendering) of the underlying fine grain scattering density of tissues based on power law constraints. The key steps are a whitening of the spectrum of the received signal while conforming to the original envelope shape and statistics, followed by a power law filtering in accordance with the known scattering behavior of tissues. This multiple step approach results in a high-spatial-resolution map of scattering density that is constrained by the most important properties of scattering from tissues. Examples from in vivo liver scans are shown to illustrate the change in image properties from this framework.

In recent years, the single-pixel imaging technique which uses a detector without spatial resolution and spatially modulated illumination patterns to reconstruct an object image has been finding its application for imaging objects in visibility obstructing conditions such as smoke or fog. The unifying feature of the studies published so far is the proof of workability of the methods proposed by the authors to improve the quality of single-pixel imaging images at their chosen scattering medium parameters without revealing the limits of applicability. This work experimentally demonstrates the influence of the number of scattering particles in the medium on the contrast of single-pixel images, and also compares the results with images obtained with a CCD camera, which allows not only to compare imaging methods under varying conditions, but also to evaluate the influence of losses introduced by the presence of a scattering medium on the contrast of single-pixel images. This work uses the classical experimental scheme of single-pixel imaging in which the single-pixel detector and focusing lens were replaced by a CCD camera to obtain images for comparison. A cuvette containing milk solution of different concentrations was placed between the object and the detector. For each concentration, an image of the object was reconstructed using the single-pixel imaging method and then recorded on the CCD camera until the concentration of the scattering agent was reached at which no image could be obtained by either method. The contrast was then calculated for each image obtained. It is shown that the single-pixel imaging method for milk concentrations up to 1/150 has an average contrast of 0.21, which does not decrease as the scattering increases. At the same time for CCD camera the contrast in the absence of scattering is 0.70, and with increasing milk concentration monotonically decreases to 0.07. The main feature of images obtained by single-pixel imaging through scattering media is the preservation of contrast as the concentration of the scattering medium increases indicating that the relationships between all the recorded on a single-pixel detector intensities used in the construction of the correlation function are preserved. A single-pixel image ceases to be reconstructed only when information about the object does not reach the detector due to multiple scattering and absorption produced by a milk solution. The considered features show the prospect of using single-pixel imaging for the construction of remote sensing systems with pattern recognition, as they allow obtaining similar images at different scattering coefficients of the scattering medium.

This review is based on the radar cross-section (RCS) reduction techniques, with the prominence of the metasurface and its design. The thorough detail starts with introducing the concepts of the RCS and its reduction techniques. Then, traditional and recent techniques are provided to reduce RCS, emphasizing the scattering and absorption methods. An in-depth analysis of shaping processes and Radar Absorbing Materials (RAM) is provided, which are two standard RCS reduction techniques. It also thoroughly analyses the metamaterial-based RCS reduction, considering both active and passive configurations. The primary aspects covered regarding the utilization of metasurfaces for reducing RCS include profile, conformality, polarization sensitivity, and design complexity. To provide comparison and evaluation, the review includes tabulated information on performance parameters such as the method used, frequency range, size, optimization method, and planar or conformal design of RCS reduction. Additionally, the paper identifies areas within the field that require further in-depth research and investigation.

Reciprocal scatterers necessarily extinguish the same amount of incoming power when excited from opposite directions. This property implies that it is not possible to realize scatterers that are transparent when excited from one direction but that scatter and absorb light for the opposite excitation, limiting opportunities in the context of asymmetric imaging and nanophotonic circuits. This reciprocity constraint may be overcome with an external bias that breaks time-reversal symmetry, posing however challenges in terms of practical implementations and integration. Here, we explore the use of tailored nonlinearities combined with geometric asymmetries in suitably tailored resonant nanoantennas. We demonstrate that, under suitable design conditions, a nonlinear scatterer can be cloaked for one excitation direction, yet strongly scatters when excited at the same frequency and intensity from the opposite direction. This nonreciprocal scattering phenomenon opens opportunities for nonlinear nanophotonics, asymmetric imaging and visibility, all-optical signal processing and directional sensing.

This study utilizes 3D numerical models to simulate seismic resonances in a volcanic edifice, arising from the interaction between an externally excited wavefield and a magma chamber-conduit system. The magma chamber and conduit efficiently capture the incident wavefield of both P- and S-waves, excited by a high-frequency (~10 Hz) earthquake located within the edifice. Due to multiple internal reflections off the boundaries of the chamber and conduit, prolonged reverberations occur, which are guided along the conduit. Temporal and spectral analyses of synthetic seismograms illustrate that models with larger chambers and wider conduits consistently yield larger resonance amplitudes at distinct frequencies. Our models indicate that a larger magma chamber can produce an intensified scattered wavefield with a broad frequency range, observable up to several hundred meters away from the central conduit. Generally, these externally initiated ‘calabash resonances’ may appear as tremor-like signals at seismometers on the edifice, accompanying more conventional seismic events in its proximity.

Self-healing optical beams are a class of propagation modes that can recover their beam shapes after distortion or partial blockage. This self-healing property makes them attractive for use in applications involving turbid media as they can—in theory—penetrate further into these materials than standard Gaussian beams. In this paper, we characterize the propagation of two different self-healing beams (Bessel and Airy) through a solid scattering material with different scatterer concentrations and find that both beams do recover after scattering for samples below a threshold scatterer concentration. Additionally, we test the applicability of both beam shapes for improved sub-surface spectroscopy in heterogeneous materials using fluorescent particles and find that there is an average fluorescence intensity enhancement of 1.3× using self-healing beams versus a standard Gaussian beam.

Inhomogeneities in the near-surface region of diffusion-doped silicon with manganese atoms were studied using the local photo-EMF method and photovoltage and photoconductivity signals were detected. It has been established that the inhomogeneous region is located at a depth of 3÷35 μm from the surface of the crystal. The magnitude of photo-EMF in these layers does not change monotonically from point to point. It was revealed that the photo-EMF spectra depend on the wavelength of the irradiated light, while the shape of the areas and their shift are related to the penetration depth of laser radiation. The photo-EMF signal increases to a depth of ~25 µm from the surface, then saturates and from ~30 µm smoothly decreases and completely disappears at a depth of ~40 µm. The magnitude of the internal electric field was determined using the Tauc method. A model of the structure of the near-surface region of diffusion-doped silicon with manganese is proposed.

Skyglow from sources of artificial light at night poses a significant challenge to ground-based astronomical research and discovery. Although astronomers, conservationists, and light-pollution researchers have measured skyglow for decades, their data on diffuse night-time light fields are incomplete as they lacks information about the polarization state of the light. Here, we present the first successful theoretical model that predicts the degree and angle of linear polarization of scattered night sky light and accounts for complex, real-world distributions of ground light sources. The model proceeds from an analytical solution to the polarized radiative transfer equation that is validated by field experiments. We discuss several use cases of the model and demonstrate its practical consequences, such as the ability to more reliably determine which ground sources in the area around an observer contribute the most scattered light in a given sky element. [ABSTRACT FROM AUTHOR]

The eclipses seen in the radio emission of some pulsars can be invaluable to study the properties of the material from the companion stripped away by the pulsar. We present a study of six consecutive eclipses of PSR J0024–7204O in the globular cluster 47 Tucanae as seen by the MeerKAT radio telescope in the UHF (544–1088 MHz) band. A high scintillation state boosted the signal during one of the orbits and allowed a detailed study of the eclipse properties. We measure significant dispersion measure (DM) variations and detect strong scattering that seems to be the dominating mechanism of the eclipses at these frequencies. A complete drop in the linear polarization together with a small increase in the rotation measure suggests the presence of a magnetic field of |$\sim 2$|  mG. The study of multiple eclipses allowed us to measure difference in the lengths of the eclipses and DM differences of |$\sim 0.01$|  pc cm |$^{-3}$| in consecutive orbits. One orbit, in particular, shows a delay in recovery of the linear polarization and a visible delay in the arrival of the pulses caused by a stronger scattering event. We suggest that these are caused by a higher variance of density fluctuations during the event. [ABSTRACT FROM AUTHOR]

Underwater optical wireless communication (UOWC) systems provide the potential to establish secure high-data-rate communication links in underwater environments. The uniqueness of oceanic impairments, such as absorption, scattering, oceanic turbulence, and air bubbles demands accurate statistical channel models based on empirical measurements for the development of UOWC systems adapted to different types of water and link conditions. Recently, generalized Gamma and a mixture of two generalized Gamma probability density functions (PDF) were proposed to describe the statistical behavior of small and large air bubbles, respectively, when considering several levels of particle-induced scattering. In this paper, we derive novel closed-form analytic expressions to compute the bit error rate (BER) and outage performance using both proposed PDFs for various scattering conditions. Furthermore, simple asymptotic expressions are obtained to determine the diversity order of each scenario. Monte Carlo simulation results verify the obtained theoretical expressions. Our results also reveal that UOWC systems present lower BER and outage performance under more turbid water cases with respect to the tap water case due to the higher diversity order and despite the significant increases in pathloss at short link distances. Particle-induced scattering provides an inherent mechanism of turbid waters to mitigate air bubble-induced fluctuations and light blockages. [ABSTRACT FROM AUTHOR]

The Mg ii resonance doublet at 2796 Å and 2803 Å is an increasingly important tool to study cold, |$T \sim 10^{4}\,$|  K, gas – an observational-driven development requiring theoretical support. We develop a new Monte Carlo radiative transfer code to systematically study the joined Mg ii and Ly α escape through homogeneous and 'clumpy' multiphase gas with dust in arbitrary three-dimensional geometries. Our main findings are (i) the Mg ii spectrum differs from Ly α due to the large difference in column densities, even though the atomic physics of the two lines are similar. (ii) The Mg ii escape fraction is generally higher than that of Ly α because of lower dust optical depths and path lengths – but large variations due to differences in dust models and the clumpiness of the cold medium exist. (iii) Clumpy media possess a 'critical covering factor' above which Mg ii radiative transfer matches a homogeneous medium. The critical covering factors for Mg ii and Ly α differ, allowing constraints on the cold gas structure. (iv) The Mg ii doublet ratio |$R_{\rm MgII}$| varies for strong outflows/inflows (⁠|$\gtrsim 700 \,\mathrm{km\, s}^{-1}$|⁠), in particular, |$R_{\rm MgII}\lt 1$| being an unambiguous tracer for powerful galactic winds. (v) Scattering of stellar continuum photons can decrease |$R_{\rm MgII}$| from two to one, allowing constraints on the scattering medium. Notably, we introduce a novel probe of the cold gas column density – the halo doublet ratio – which we show to be a powerful indicator of ionizing photon escape. We discuss our results in the context of interpreting and modelling observations as well as their implications for other resonant doublets. [ABSTRACT FROM AUTHOR]

For a better understanding of the physico-chemistry in the interstellar medium, collisional data are needed. In this work, we provide rate coefficients for the recently detected by Cabezas and collaborators in 2023 sodium cyanoacetylide molecule NaC |$_{3}$| N(⁠|$X^{1}\Sigma ^{+}$|⁠) induced by collisions with He. A new two-dimensional potential energy surface (2D-PES) is derived by adopting the high-level theory of the explicitly correlated coupled cluster with single, double, and perturbative triple excitations (CCSD(T)-F12) in conjunction with the aug-cc-pVTZ basis sets. Our 2D-PES presents two minima: the global one with a well depth of |$-86.58$|  cm |$^{-1}$| and the second well with a |$-47.01$|  cm |$^{-1}$| depth. This was expected by the Natural Bond Orbital analysis showing two electrophilic zones located on Na and N linked Carbon with respective atomic charges : |$+0.96575$| and |$+0.28910$|⁠. This PES was used to calculate inelastic cross-sections within the framework of the close-coupling theory for total energies |$\le 170$|  cm |$^{-1}$| and |$J\le 22$|⁠. Using the Maxwell–Boltzmann distribution of kinetic energies, these cross-sections were integrated to generate the collisional (de)-excitation rate coefficients for temperatures below 30 K. In order to estimate the impact of the computed collisional rates, a non-local thermodynamical equilibrium radiative transfer calculation was performed. The new collisional data can allow accurate NaC |$_{3}$| N abundance determination in the interstellar medium. [ABSTRACT FROM AUTHOR]

The proposed revisit to a classical problem in fluid–structure interaction is due to an interest in the analysis of the narrow resonances corresponding to a low-frequency fluid-borne wave, inspired by modeling and design of metamaterials. In this case, numerical implementations would greatly benefit from preliminary asymptotic predictions. The normal incidence of an acoustic wave is studied for a circular cylindrical shell governed by plane strain equations in elasticity. A novel high-order asymptotic procedure is established considering for the first time all the peculiarities of the low-frequency behavior of a thin fluid-loaded cylinder. The obtained results are exposed in the form suggested by the Resonance Scattering Theory. It is shown that the pressure scattered by rigid cylinder is the best choice for a background component. Simple explicit formulae for resonant frequencies, amplitudes, and widths are presented. They support various important observations, including comparison between widths and the error of the asymptotic expansion for frequencies. [ABSTRACT FROM AUTHOR]

This review is based on the radar cross-section (RCS) reduction techniques, with the prominence of the metasurface and its design. The thorough detail starts with introducing the concepts of the RCS and its reduction techniques. Then, traditional and recent techniques are provided to reduce RCS, emphasizing the scattering and absorption methods. An in-depth analysis of shaping processes and Radar Absorbing Materials (RAM) is provided, which are two standard RCS reduction techniques. It also thoroughly analyses the metamaterial-based RCS reduction, considering both active and passive configurations. The primary aspects covered regarding the utilization of metasurfaces for reducing RCS include profile, conformality, polarization sensitivity, and design complexity. To provide comparison and evaluation, the review includes tabulated information on performance parameters such as the method used, frequency range, size, optimization method, and planar or conformal design of RCS reduction. Additionally, the paper identifies areas within the field that require further in-depth research and investigation. [ABSTRACT FROM AUTHOR]

Recent experimental observation in thermal-induced gelation of silica-based shear thickening fluids (STFs) has necessitated the efforts to address the thermal instability of the STFs. The shear thickening behavior of hydrophilic fumed silica/PEG disappeared after thermal treatment. Hydrophobic surface is demonstrated to enhance thermal stability of the fumed silica/PEG system under the same thermal treatment. Dynamic temperature sweep experiments reveal a temperature-induced sol–gel transition of the hydrophilic silica/PEG. Meanwhile, hydrophobic silica/PEG does not undergo such gelation and still displays viscosity thickening after thermal treatment. This gelation process is found to be concentration-dependent and irreversible, with enhanced gelation at higher specific surface areas of hydrophilic silica particles. The small-angle X-ray scattering (SAXS) studies suggest that this sol–gel transition is likely attributed to the reduction of solvation layer which could be highly influenced by particle surface hydrophilicity. Comprehensive experiments, including Soxhlet extraction and rheology, confirm that the resulting stable three-dimensional structure is not formed by chemical crosslinks but behaves as a physical network. It is demonstrated how tailoring particle–medium interactions through controlling particle surface characteristics can be used to improve thermal stability of silica-based STFs. [ABSTRACT FROM AUTHOR]

Most measurements of the diffuse light of the night sky to date consider only the intensity of the light field, and current models can successfully reproduce these measurements. However, this approach is incomplete as it overlooks the polarization state of the light. Few measurements (and no successful models) of night-sky polarimetry appear in the literature. We present a new model of night-sky polarization that successfully reproduces observations in a heterogeneous environment and for a real distribution of finite-sized light sources over the intermediate region surrounding the observer. The model compares favourably with field measurements made in Slovakia in 2021 May. The results described herein help advance understanding of the angular distributions of artificial light at night from ground sources and the relative contributions of sources to the overall brightness of the night sky. [ABSTRACT FROM AUTHOR]

• Observation of Multiple layer structures (Temperature Sheets) around the tropopause region and lower stratosphere. • Strong hydrostatic stability responsible for the intensity gradient in the radio refractive index. • Temperature sheets in the troposphere have significant implications for weather and atmospheric stability. • Higher-order spectral analysis has been applied to the atmospheric signals to detect the nonlinearities associated with the temperature sheets near the tropopause region. • Large shear region shows the temperature variation, which results in temperature sheet formation near the tropopause region. Temperature sheets have been observed in the lower stratosphere up to 20 km, with strong (positive) temperature gradients within very thin layers. These were observed from vertical profiles obtained from the Stratosphere and Troposphere (ST) radar located in Kolkata. The sheets tend to occur in groups and contribute to the regions of high static stability, inhibiting vertical air motion. Several experiments were carried out to understand the backscattering mechanism of the Very High Frequency (VHF) radar. Many experiments have reported the multiple layered structures at and around the tropopause regions, especially in the lower stratosphere, it is well established that these layered structures are due to presence of strong negative and positive temperature gradients, which is called as temperature sheets. In order to understand the nonlinearities associated with temperature sheets, Higher-order spectral analysis has been carried out on backscattered signals received from the Mesosphere Stratosphere and Troposphere (MST) radar. This approach allowed for a more detailed examination of the nonlinearities associated with temperature sheets. Therefore, this study proposes a new way of distinctly identifying temperature sheets and the process associated with them using Nonlinear Index based measurements. [ABSTRACT FROM AUTHOR]

This study aimed to examine the mechanisms of the photoplethysmography (PPG) signal formation using Monte Carlo simulations of light transport in biological tissues and experimental observations. Based on a three-layer skin model in backscattering geometry, we sequentially simulated volumetric blood changes and the aggregation/disaggregation of erythrocytes in the dermal layer and estimated their contribution to the registered PPG signal. The calculations were conducted for two wavelengths: 525 nm and 810 nm. For green light, absorption predominates over scattering in the formation of a PPG signal, whereas, for near-infrared light, scattering prevails over absorption. This theoretical result was verified using the Modified Beer–Lambert law and clinical in vivo PPG data of seven healthy subjects. Changes in the size of the scatterers during erythrocyte aggregation and disaggregation can significantly contribute to the PPG signal at near-infrared light. Thus, for the green waveband, the classical volumetric model can be considered dominant in the PPG signal formation. In contrast, for the near-infrared range, both volumetric and aggregation effects must be considered as being approximately equal. [ABSTRACT FROM AUTHOR]

We present a theoretical framework for linking quasar properties, such as quasar age, to the surrounding Ly α emission intensity. In particular, we focus on a method for mapping the large-scale structure of Ly α emission intensity with galaxy spectra from wide-field spectroscopic surveys, e.g. the Subaru Prime Focus Spectrograph (PFS) or the Dark Energy Spectroscopic Instrument (DESI), and consider the quasar-induced Ly α emission from the intergalactic medium (IGM). To do this, we construct a theoretical model based on two physical processes: resonant scattering of quasar Ly α photons and fluorescence due to quasar ionizing photons, finding that the fluorescence contribution due to optically thick gas clouds is dominant. Taking into account the light-cone effect and assuming a typical quasar spectrum, we calculate the fluorescence contribution to the spectrum stacked within each bin of the separation angle from the quasar as a function of quasar age. Furthermore, we compute the quasar-Ly α emission cross-correlation and its SNR for the planned PFS survey. The predicted signal can only account for |$\sim 10~{{\ \rm per\ cent}}$| of the measurements indicated from the BOSS and eBOSS surveys in the outer region of |$\gtrsim 10\ \rm {cMpc}\ \rm {h}^{-1}$|⁠ , and the predicted SNR is not sufficient to detect the quasar-induced contribution. However, we found that our model, combined with the contribution of star-forming galaxies, is not in conflict with these measurements. We discuss other possible contributions to the Ly α emission excess around quasars, the efficiency of using spectroscopic fibres, and the redshift dependence of our model. [ABSTRACT FROM AUTHOR]

In absorption spectroscopy, it is challenging to detect absorption peaks with significant differences in their intensity in a single measurement. We enable high-dynamic-range measurements by dispersing scatterers within a sample to create a broad distribution of path lengths (PLs). The sample is placed within an integrating sphere (IS) to capture all scattered light of various PLs. To address the complexities of PLs inside the IS and the sample, we performed a ray-tracing simulation using the Monte Carlo (MC) method, which estimates the measured absorbance A and PL distribution from the sample's absorption coefficient µa and scattering properties at each wavelength λ. This method was validated using dye solutions with two absorption peaks whose intensity ratio is 95:1, employing polystyrene microspheres (PSs) as scatterers. The results confirmed that both peak shapes were delineated in a single measurement without flattening the high absorption peak. Although the measured peak shapes A(λ) did not align with the actual peak shapes µa(λ), MC enabled the reproduction of µa(λ) from A(λ). Furthermore, the analysis of the PL distribution by MC shows that adding scatterers broadens the distribution and shifts it toward shorter PLs as absorption increases, effectively adjusting it to µa. [ABSTRACT FROM AUTHOR]

Plasmonic metal nanostructures can simultaneously scatter and absorb light, with resonance wavelength and strength depending on their morphology and composition. This work demonstrates that unique dichroic effects and high‐contrast colour‐switching can be achieved by leveraging the resonant scattering and absorption of light by plasmonic nanostructures and the specular reflection of the resulting transmitted light. Using core/shell nanostructures comprising a metal core and a dielectric shell, we show that their spray coating on reflective substrates produces dichroic films that can display colour switching at different viewing angles. The high‐contrast colour switching, high flexibility in designing multicolour patterns, and convenience for large‐scale production promise their wide range of applications, including anticounterfeiting, mechanochromic sensing, colour display, and printing. [ABSTRACT FROM AUTHOR]