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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.

This work provides the first combined analysis of low-energy pΛ scattering, considering both cross section and correlation data. The obtained results establish the most stringent constraints to date on the two-body pΛ interaction, pointing to a weaker attraction than so far accepted. The best set of scattering lengths for the spin singlet and triplet are found to range from f0,f1=(2.1,1.56) to (3.34,1.18) fm. With a chiral NY potential fine-tuned to those scattering parameters, the in-medium properties of the Λ are explored and a potential depth of UΛ=−36.3±1.3(stat)−6.2+2.5(syst) MeV is found at nuclear matter saturation density.

Dust particles and sand storms can cause attenuation and cross-polarization of electromagnetic wave propagation, especially at high frequencies above 10 GHz. Dust attenuation has been the focus of many research works, mainly with the deployment of a 5G wireless network in the FR-2 band (mmWave band, 23–53 GHz with TDD). This has led to the development of novel models to accurately predict and estimate attenuation. However, the existing review works have not adequately provided extensive taxonomies for these models to show the state-of-art and future research directions. This paper aims to bridge this gap by providing a comprehensive review of all electromagnetic scattering models in terms of their strengths, weaknesses, and applications. Lessons learned from the detailed survey have been stated and discussed extensively. Key findings from this review indicate that all the models developed were limited to the region where they were developed, with frequency and visibility levels as the two main parameters. The survey across regions showed no model was developed for Region 2, including the Americas, Greenland, and some of the eastern Pacific Islands. Among the dry regions of the globe, where dust and sand storms can occur either occasionally or frequently, it can be seen that only a few parts of these desert regions of Africa (Region 1) and Asia (Region 3) have been considered by authors for the development of prediction models for attenuation due to dust storms. Thus, this also shows the limitations of the overall deterministic models and presents the crucial need to develop new models or modify existing models to accurately predict dust attenuation in other regions, particularly in Africa.

In this paper, the first order perturbation theory (PT) and the small slope approximation (SSA) are employed to analyze the scattering behavior of a two dimensional dielectric-topological insulator (TI) rough interface with Gaussian distribution. Zeroth and first order scattering amplitudes are utilized to obtain the analytic expressions for the coherent and incoherent intensities, respectively. For vertical incidence, an equation can be found whose numerical solution gives the Brewster angle at which the co polarized coherent intensity becomes zero. The scattering scenarios are analyzed where both polarization states of the incident field exhibit total depolarization and the co polarized incoherent scattering is zero.

This work presents the study of the thermodynamic properties of thermal electrons participating in scattering events. This is necessary because scattering with a thermal electron in presence of a laser field was not studied yet and it reduces the complexity of event measurement (differential cross-section). To study thermodynamic properties, the authors model the thermal Hamiltonian in presence of a laser field and used it to study the thermodynamic properties using the partition function. The study shows thermodynamic energy, around the target with distance at field amplitude 0.1 a.u. to 0.9 a.u. has destructive interference, above field amplitude 1 a.u. to 2.5 a.u. has superposition and at field amplitude 2.5 a.u. and 3 a.u. have coulomb potential like nature. Also, thermodynamic energy with temperature was found constant except at field amplitude 2.5 a.u. and at field amplitude 2.5 a.u. destructive interference at 10 °C and 21 °C. The thermodynamical potential at field amplitude 0.1 to 3.5 a.u. found constant and above field amplitude 3.5 a.u. increased linearly when studied with respect to temperature at 10 Å. The thermal Hamiltonian increase sharply when thermal electrons enter in 1–5 Å, slowly in 5–10 Å and beyond 10 Å constant, and the thermal Hamiltonian nature is like coulomb potential.

We investigate the well-posedness theory of the 2-D fractional nonlinear Schrödinger equation (NLSE) with a mixed degree of derivatives. Motivated by models in optics and photonics where the light propagation is governed by non-quadratic, fractional, and anisotropic dispersion profile, this paper presents first results in this direction. Dispersive estimates are developed in the context of anisotropic Sobolev spaces defined by inhomogeneous symbols. The main model is shown to exhibit scattering for small data in the scaling-critical space. Furthermore the continuity of solution with respect to the dispersion parameter is shown on a compact time interval.

We presented an interpolation method for solving weakly singular Volterra integral equations of the second kind (SVK2). The method based on the barycentric Lagrange interpolation.. For the chosen nodes of the two singular kernel variables, we created two rules that confirm that the denominator of the kernel will never become zero or have an imaginary value. The product of four matrices, one of which is the square coefficients matrix of the barycentric functions, expresses both the unknown and data functions. The singular kernel is interpolated twice with to its two variables. Furthermore, the kernel is represented by five matrices: two of which are the monomial basis of the kernel's variables, and one matrix expresses the kernel's values at the two sets of nodes for the kernel's variables. Without using the collocation approach, we get the matrix of the unknown coefficients by substituting the interpolated solution into the integral equation to obtain an equivalent algebraic system. By solving the algebraic system, we get the interpolated solution. We solved five examples, two for non-singular equations and three for weakly singular equations. By adopting lower interpolation degrees, the interpolated solutions for non-singular equations are shown to be equal to the exact ones, whereas, for singular equations, they are found to strongly converge to the exact ones and are superior to those obtained by other cited methods. This ensures the proposed method's uniqueness and high accuracy.

Optical imaging of objects at the nanometric scale is limited by light diffraction, and for this reason several sub-diffractive optical microscopy techniques have been developed in the last decades. In this article we present an optical laser microscope specifically designed for detection of nano-materials exploiting the Mie scattering between the evanescent wave generated by a laser beam travelling in a transparent substrate through total internal reflection and the nano-objects deposited on the substrate itself. The setup, including the laser source, can be fully integrated inside an optical microscope requiring only a geometric alignment with the substrate thus reducing the complexity and the cost. We also report two possible applications: quantitative detection of Au nanoparticles in the 20-100 nm size range and semi-quantitative detection of virions immobilized on the substrate through bioreceptor / antigen binding, including, but not limited to, SARS-CoV-2. A minimum virus amount of ≈105 in the reaction volume is observed. The results presented here open the route towards unprecedent applications in molecular biology or molecular diagnostics.

We present a multimer coupling classic harmonic oscillator model to reveal the scattering and photoluminescence (PL) properties of metallic nanoparticle chains. Taking particle number from 1 to 6 as examples, we compare the calculated spectra with the experimental ones from other researchers’ work, and they agree well with each other. Furthermore, scattering and PL properties are analyzed carefully varying with particle number n, coupling strength g, and effective free electron number N. Results indicates larger red-shift and smaller full width at half maximum (FWHM) of the scattering spectra with larger n or/and larger g. Particularly, the limitation of the red-shift is obtained in the limit of n→∞. Meanwhile, the splitting of PL modes increases as g increases, and the amplitudes are dependent on the excitation wavelength. This classic model is simple and shows a unified treatment for understanding the scattering and PL properties of multimer coupled systems.

Ionic Liquids are often characterized by multiple length scales and these tend to be well separated. As an example, for 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide apolar pockets or domains are separated by a characteristic distance that is different from that of positive-negative charge alternation along a charge network. Accordingly, these structural features have their own well separated signatures in the reciprocal space structure function. Each of these well separated structural features of prototypical ionic liquids relaxes on its own time scale and we have explored this in a set of recent articles. The overarching goal of the current work is to explore what happens when the structural motifs are still present, but the length scale difference between these is small. Specifically, for ionic liquids containing ether tail functionalities such as 1-(2-(2-ethoxyethoxy)ethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, the separation between cationic head subspecies intercalated by anions (or anions sharing a cationic head counterion) is not that different from that of cationic heads or anions intercalated by tail regions and the time scale for relaxation of these structural motifs are also similar. For the ether-tail containing system, the slowest liquid relaxation scale associated with tail region-charge network correlations is about an order of magnitude faster than for its alkyl-tail isoelectronic analog.

In this study, a facile fluorescence-scattering ratiometric sensor was designed for visual and selective detection of levodopa (LD) via a clever physicochemical modulation scheme. The alkalized products of LD can rapidly react with polyethyleneimine (PEI) to exhibit an intense blue fluorescence and decrease the second-order scattering (SOS) signal of PEI. As the concentration of LD increased, the fluorescence intensity at 420 nm increased and the SOS intensity at 675 nm decreased synchronously. Thus the fluorescence-scattering ratiometric sensor was constructed by virtue of the two simultaneously changed signals. Furthermore, red light-emitting Au nanoclusters (AuNCs) were added into the above mixture solution to enlarge the SOS signal and provide a stable red background fluorescence. The intensity ratio of fluorescence to SOS (F/(S/S blank )) is linear dependent on C LD in the wide range of 50.0---30000.0 nM, and LD as low as 50.0 nM can be identified with the naked eye via change of fluorescence color. The developed ratiometric sensor is smart, simple and efficient, and has been applied to the convenient assay of LD in real samples. The proposed physicochemical modulation strategy provides a new and facile path for selectively and visually identifying the target from its analogues., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Celestial objects such as stars and planets might be able to capture a large amount of dark matter particles through dark matter-nucleon scattering. Many previous studies have considered different celestial objects such as the Sun and the Earth as natural dark matter detectors and obtained some stringent bounds of the dark matter-nucleon scattering cross section. In this study, we use the ∼10 MeV electron neutrino flux limits obtained by the Super-Kamiokande experiment and consider the Earth as a large natural dark matter detector to constrain the dark matter-nucleon scattering cross section. We show that this method can generally get more stringent limits. For certain ranges of dark matter mass annihilating via the bb¯ channel, the limits of cross section for the isospin-independent scattering and proton-only scattering could be more stringent than that obtained in the PICO direct-detection experiment.

Summary: The aim of this study was to investigate the light transfer through sea ice with a focus on bio-optical substances both in fast ice and in the drift ice zones in the northern Baltic Sea. The measurements included snow and ice structure, spectral irradiance and photosynthetically active radiation below the sea ice. We also measured the concentrations of the three main bio-optical substances which are chlorophyll-a, suspended particulate matter, and coloured dissolved organic matter (CDOM). These bio-optical substances were determined for melted ice samples and for the underlying sea water. The present study provides the first spectral light transfer data set for drift ice in the Baltic Sea. We found high CDOM absorption values typical to the Baltic Sea waters also within sea ice. Our results showed that the transmittance through bare ice was lower for the coastal fast ice than for the drift ice sites. Bio-optical substances, in particular CDOM, modified the spectral distribution of light penetrating through the ice cover. Differences in crystal structure and the amount of gas inclusions in the ice caused variation in the light transfer. Snow cover on ice was found to be the dominant factor influencing the light field under ice, confirming previous studies. In conclusion, snow cover dominated the amount of light under the ice, but did not modify its spectral composition. CDOM in the ice absorbs strongly in the short wavelengths. As pure water absorbs most in the long wavelengths, the light transfer through ice was highest in the green (549–585 nm).

A state-of-the-art encapsulation technique for evaluating a photovoltaic device in laboratory is needed for replicating real-time devices. In this context, earlier we proposed the pouch lamination as a cost-effective and reproducible lab-scale encapsulation technique. In this work, we apply this technique in evaluating the optical and electrical performances of a mc-Si device with a front spectral shifting layer before and after encpasulation. Our coating contains the red-emitting nitride phosphor CaAlSiN3:Eu2+ (CASN:Eu2+) in (poly)-methyl methacrylate (PMMA). On coating, a drastic reduction in the device's reflectance was observed below 450 nm. Correspondingly, the external and internal quantum efficiencies of the devices are also improved relative to the bare. When irradiated by an AM1.5G source, the electrical parameters remain of the device remain unaffectd after the coating. However, on encapsulating the coated device, impedance losses drastically reduce its conversion efficiency. This paper thus reveals the need for including an encapsulant while demonstrating device modifications through optical coatings.

Multifunctional bio-adhesives with tunable mechanical properties are obtained by controlling the orientation of anisotropic particles in a blend of fast-curing hydrogel with an imposed capillary flow. The suspensions' microstructural evolution was monitored by the small-angle light scattering (SALS) method during flow up to the critical Péclet number (Pe≈1) necessary for particle orientation and hydrogel crosslinking. The multifunctional bio-adhesives were obtained by combining flow and UV light exposure for rapid photo-curing of PEGDA medium and freezing titania rods' ordered microstructures. Blending the low- and high-molecular weight of PEGDA polymer improved the mechanical properties of the final hydrogel. All the hydrogel samples were non-cytotoxic up to 72 h after cell culturing. The system shows rapid blood hemostasis and promotes adhesive and cohesive strength matching targeted tissue properties with an applicating methodology compatible with surgical conditions. The developed SALS approach to optimize nanoparticles' microstructures in bio-adhesive applies to virtually any optically transparent nanocomposite and any type of anisotropic nanoparticles. As such, this method enables rational design of bio-adhesives with enhanced anisotropic mechanical properties which can be tailored to potentially any type of tissue., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Accurate light dosimetry is a complex remaining challenge in interstitial photodynamic therapy (iPDT) for malignant gliomas. The light dosimetry should ideally be based on the tissue morphology and the individual optical tissue properties of each tissue type in the target region. First investigations are reported on using NMR information to estimate changes of individual optical tissue properties., Methods: Porcine brain tissue and optical tissue phantoms were investigated. To the porcine brain, supplements were added to simulate an edema or high blood content. The tissue phantoms were based on agar, Lipoveneous, ink, blood and gadobutrol (Gd-based MRI contrast agent). The concentrations of phantom ingredients and tissue additives are varied to compare concentration-dependent effects on optical and NMR properties. A 3-tesla whole-body MRI system was used to determine T 1 and T 2 relaxation times. Optical tissue properties, i.e., the spectrally resolved absorption and reduced scattering coefficient, were obtained using a single integrating sphere setup. The observed changes of NMR and optical properties were compared to each other., Results: By adjusting the NMR relaxation times and optical tissue properties of the tissue phantoms to literature values, recipes for human brain tumor, white matter and grey matter tissue phantoms were obtained that mimic these brain tissues simultaneously in both properties. For porcine brain tissue, it was observed that with increasing water concentration in the tissue, both NMR-relaxation times increased, while µ a decreased and µ s ' increased at 635 nm. The addition of blood to porcine brain samples showed a constant T 1 , while T 2 shortened and the absorption coefficient at 635 nm increased., Conclusions: In this investigation, by changing sample contents, notable changes of both NMR relaxation times and optical tissue properties have been observed and their relations examined. The developed dual NMR/optical tissue phantoms can be used in iPDT research, clinical training and demonstrations., Competing Interests: Declaration of competing interest The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The properties of upconverting nanoparticles (UCNPs) are crucial for their applications in biomedicine. For studies of organisms and biological materials, the penetration depth of excitation light is also essential as the depth from which the luminescence can be detected. Currently, many researchers are trying to obtain UCNPs with intense emission under excitation wavelengths from the biological transparency windows to increase the penetration depth. However, studies comparing the properties of various types of UCNPs in real conditions are rare. This article shows how deep the 808, 975, 1208, and 1532 nm laser radiation penetrates human blood. Moreover, we determined how thick a layer of blood still permits for observation of the luminescence signal. The measured luminescence properties indicated that the near-infrared light could pass through the blood even to a depth of 7.5 mm. The determined properties of core/shell NaErF 4 /NaYF 4 materials are the most advantageous, and their emission is detectable through 3.0 mm of blood layer using a 1532 nm laser. We prove that the NaErF 4 /NaYF 4 UCNPs can be perfect alternatives for the most studied NaYF 4 :Yb 3+ ,Er 3+ /NaYF 4 . Additionally, the setup proposed in this article can potentially decrease reliance on animal testing in initial biomedicine research., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tomasz Grzyb reports financial support was provided by National Science Centre Poland. Natalia Jurga reports financial support was provided by European Social Fund., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Tendons are collagen-based connective tissues where the composition, structure and mechanics respond and adapt to the local mechanical environment. Adaptation to prolonged inactivity can result in stiffer tendons that are more prone to injury. However, the complex relation between reduced loading, structure, and mechanical performance is still not fully understood. This study combines mechanical testing with high-resolution synchrotron X-ray imaging, scattering techniques and histology to elucidate how reduced loading affects the structural properties and mechanical response of rat Achilles tendons on multiple length scales. The results show that reduced in vivo loading leads to more crimped and less organized fibers and this structural inhomogeneity could be the reason for the altered mechanical response. Unloading also seems to change the fibril response, possibly by altering the strain partitioning between hierarchical levels, and to reduce cell density. This study elucidates the relation between in vivo loading, the Achilles tendon nano-, meso‑structure and mechanical response. The results provide fundamental insights into the mechanoregulatory mechanisms guiding the intricate biomechanics, tissue structural organization, and performance of complex collagen-based tissues. STATEMENT OF SIGNIFICANCE: Achilles tendon properties allow a dynamic interaction between muscles and tendon and influence force transmission during locomotion. Lack of physiological loading can have dramatic effects on tendon structure and mechanical properties. We have combined the use of cutting-edge high-resolution synchrotron techniques with mechanical testing to show how reduced loading affects the tendon on multiple hierarchical levels (from nanoscale up to whole organ) clarifying the relation between structural changes and mechanical performance. Our findings set the first step to address a significant healthcare challenge, such as the design of tailored rehabilitations that take into consideration structural changes after tendon immobilization., Competing Interests: Declaration of Competing Interest The authors have no financial/commercial Conflict of Interest., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Quantum theory is proposed of high energy electrons scattering in ultrathin crystals. This theory is based upon a special representation of the scattering amplitude in the form of an integral over the surface surrounding the crystal, and on the spectral method of determination of the wave function. The comparison is performed of quantum and classical differential scattering cross-sections in the transitional range of crystal thicknesses, from those at which the channeling phenomenon is not developed up to those at which it is established. It is shown that in this thickness range the quantum scattering cross-section, unlike the classical one, contains sharp peaks corresponding to some specific scattering angles, that is connected with the diffraction of the incident plane wave onto the periodically distributed crystal atomic strings. It is shown that the value of the scattering cross-section in the peaks varies periodically with the change of the target thickness. We note that this must lead to a new interference effect in radiation that is connected with the rearrangement of incident wave packet in transitional area of crystal thicknesses.

Quantum graph consisting of a line with attached segment is considered as a simple model of the Helmholtz resonator. Completeness of resonant states in the space of square integrable functions on the segment is proved. Relation between the completeness and the factorization of the characteristic function in Sz.-Nagy model is discussed.

Triple differential cross sections (TDCS) for the ionization of metastable 2P-state hydrogen atoms by electrons are calculated for various kinematic conditions in the asymmetric coplanar geometry. In this calculation, the final state is described by a multiple-scattering theory for ionization of hydrogen atoms by electrons. Results show qualitative agreement with the available experimental data and those of other theoretical computational results for ionization of hydrogen atoms from ground state, and our first Born results. There is no available other theoretical results and experimental data for ionization of hydrogen atoms from the 2P state. The present study offers a wide scope for the experimental study for ionization of hydrogen atoms from the metastable 2P state.

Line shapes of anionic fluorescein fluorescence in suspensions of polystyrene nanoparticles (PSNP), anionic and cationic micelles, lipid vesicles, and of laurdan in lipid vesicles were investigated. Computed second harmonic of measured spectra indicated three lines for fluorescein and two for laurdan. Accordingly, fluorescein spectra were fit to three Gaussians and laurdan spectra to two lognormal distributions. Resolved line parameters were examined against particle concentration. Scattering, although wavelength dependent, affected intensity but not line shape. Inner filter effects of scattering on line shape are insignificant because multiple scattering, redirection of scattered photons into the detector, and inclusion of scattered photons in collection and detection minimize wavelength dependent effects. Dominant effects on line width and peak positions are due to physicochemical effects of dye-particle-solvent interactions rather than scattering. Fluorescein does not interact with anionic micelles and lipid vesicles, but remains in the aqueous phase, and responds to pH increase induced by these additives. Blue shift in peak position, decrease in line width, and increase in emission intensity in these systems are like those in NaOH solutions. Fluorescein does interact with cationic micelles and hydrophobic PSNP, and its emission is red shifted. Laurdan in lipid vesicles senses interface polarity. Blue shift and decrease in line width of its emission line indicate decreasing polarity with lipid concentration. Scattering, as well as interactions affect emission intensity. Physicochemical effects distort line shape and modify intrinsic spectra. Line shape changes are better markers than intensity to investigate interactions and reactions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)