Layered Sphere Research Articles

Injectable Regenerated Silk Fibroin Micro/Nanosphere with Enhanced Permeability and Stability for Osteoarthritis Therapy.

In the therapy of early-stage osteoarthritis, to accomplish full infiltration of subchondral bone and cartilage, and to target osteoclast and chondrocyte simultaneously remain challenges in biomaterials design. Herein, a novel hierarchical drug delivery system is introduced, with micrometer-scale outer layer spheres composed of regenerated silk fibroin, characterized by connected porous structure through the n-butanol and regenerated silk fibroin combined emulsion route and freezing method. The design effectively resists clearance from the joint cavity, ensuring stable delivery and prolonged residence time within the joint space. Additionally, the system incorporates phenylboronic acid-enriched silk fibroin nanoparticles, stabilized through chemical cross-linking, which encapsulate isoliquiritin derived from Glycyrrhiza uralensis. These nanoparticles facilitate complete penetration of the cartilage extracellular matrix, exhibit pH-responsive behavior, neutralize reactive oxygen species, and enable controlled drug release, thereby enhancing therapeutic efficacy. The in vitro and in vivo experiments both demonstrate that the composite micro/nanospheres not only inhibit osteoclastogenesis with bone loss in subchondral bone and osteophyte formation, but also mitigate chondrocytes apoptosis, reduce oxidative stress associated with cartilage degeneration, and ameliorate neuropathic hyperalgesia, with the underlying mechanisms being elucidated. The study indicates that such an injectable strategy combining organic biomaterials with Chinese medicine holds substantial promise for the treatment of early osteoarthritis.

Scattering properties of dual Bessel beams on chiral layered particle

The paper investigates the scattering analytical solution of arbitrary direction double zero-order Bessel beams (ZOBBs) incident on a non-uniform layered chiral sphere. Using the generalized Lorenz-Mie theory (GLMT), the electromagnetic field expansion expression of the double ZOBBs is obtained through the vector superposition of the spherical vector wave functions (SVWFs). Analytical solutions of the scattering on chiral layered particles by dual Bessel beams are derived based on the boundary condition. The iterative coefficient equations are constructed to obtain the expansion coefficients of the SVWFs in each region of the multi-layer chiral sphere. The variation of radar cross section (RCS) with angular distribution is numerically simulated, and the scattering results of layered chiral spheres degenerated into isotropic layered spheres are compared with the literature, which verifies the correctness of the theory and program. The effects of incident angle, polarization angle, cone angle and chiral parameters on the scattering characteristics of far region and internal field of the layered chiral particle are analyzed in detail. The theory and results can offer significant assistance in studying the optical properties of non-uniform chiral particles and complex biological cells irradiated by multiple beams and may also provide important practical value in the micromanipulation of multi-layered biological structures.

Asymptotic approach for stable computations of the spherically layered media theory with large orders and small arguments.

The computation of electromagnetic wave scatterings of a layered sphere is a canonical problem. Lorentz-Mie theory is suitable for plane wave incidence whereas spherically layered media theory can deal with arbitrary incident waves. Both theories suffer from the notorious numerical instabilities due to the involved Bessel functions with large order, small argument or high loss. Logarithmic derivative method has been proposed to solve the numerical issues with these theories. In this paper, by employing the equivalence between the asymptotic formulas of Bessel functions for small argument and for large order, the numerical issues with the spherically layered theory under both large order case and small argument case can be solved in a unified manner by canceling out the diverging terms in the asymptotic formulas. The derived stable formulas are simpler and faster than those based on logarithmic derivative method. It is shown that the derived formulas are good approximations to the canonical ones but are more numerically stable. The large lossy issue can be solved similarly.

Acoustic Radiation Force on an Eccentric Layered Fluid Sphere Exerted by a Focused Gaussian Beam

Acoustic Radiation Force on an Eccentric Layered Fluid Sphere Exerted by a Focused Gaussian Beam

Determination of the Static Thermoelastic State of Layered Thermosensitive Plate, Cylinder, and Sphere

Determination of the Static Thermoelastic State of Layered Thermosensitive Plate, Cylinder, and Sphere

Numerically Stable Calculations of the Spherically Layered Media Theory

The electromagnetic scatterings of a layered sphere is a canonical problem. Mie theory is suitable for plane wave incidence case, whereas spherically layered media theory can deal with arbitrary incident waves. Both Mie theory and spherically layered media theory suffer from numerical instabilities due to the involved spherical Bessel functions when the order is large, the argument is small or the medium is lossy. Logarithmic derivative method had been proposed to solve this numerical issue with Mie theory successfully, while the numerical issue with spherically layered media theory has not been solved fully so far. Computations of reflection and transmission coefficients are the key part of spherically layered media theory. In this paper, we first define the renormalized reflection and transmission coefficients, which enjoys the feature of having an ordinary level of magnitude. Then, borrowing the idea of logarithmic derivative method, the expressions for the renormalized canonical reflection and transmission coefficients as well as other terms in the theory are rearranged. Recursive formulas for the product or division of Bessel functions with some common combinations of order and argument are derived. Numerical tests show that the proposed approach, validated by full wave numerical method, is more stable than the conventional formulation.

Submillimeter-Wave Cornea Phantom Sensing Over an Extended Depth of Field With an Axicon-Generated Bessel Beam

The feasibility of a 220–330 GHz zero-order axicon-generated Bessel beam for corneal water content was explored. Simulation and experimental data from the 25° cone angle hyperbolic-axicon lens illuminating metallic spherical targets demonstrate a monotonically decreasing, band integrated, backscatter intensity for increasing radius of curvature from 7–11 mm, when lens reflector and optical axis are aligned. Furthermore, for radii > = 9.5 mm, maximum signal was obtained with a 1-mm transverse displacement between lens and reflector optical axes arising from spatial correlation between main lobe and out-of-phase sidelobes. Thickness and permittivity parameter estimation experiments were performed on an 8-mm radius of curvature, 1-mm-thick fused quartz dome over a 10-mm axial span. Extracted thickness and permittivity varied by less than ∼25 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m and 0.2, respectively, after correction for superluminal velocity. Estimated water permittivity and thickness of water backed gelatin phantoms showed significantly more variation due to a time varying radius of curvature. To the best of our knowledge, this is the first work that describes axicon-generated Bessel beam measurements of layered spheres with varying radii of curvature, in the submillimeter range.

Space-resolved chemical information from infrared extinction spectra

A new method is presented for the extraction of the complex index of refraction from the extinction efficiency, Q_{ext} {({tilde{nu }})}, of homogeneous and layered dielectric spheres that simultaneously removes scattering effects and corrects measured extinction spectra for systematic experimental errors such as baseline shifts, tilts, curvature, and scaling. No reference spectrum is required and fit functions may be used that automatically satisfy the Kramers–Kronig relations. Thus, the method yields the complex refractive index of a sample for unambiguous interpretation of the chemical information of the sample. In the case of homogeneous spheres, the method also determines the radius of the sphere. In the case of layered spheres, the method determines the substances within each layer. Only a single-element detector is required. Using numerically computed Q_{ext}({tilde{nu }}) data of polymethyl-methacrylate and polystyrene homogeneous and layered spheres, we show that the new reconstruction algorithm is accurate and reliable. Reconstructing the complex refractive index from a published, experimentally measured raw absorbance spectrum shows that the new method simultaneously corrects spectra for scattering effects and, given shape information, corrects raw spectra for systematic errors that result in spectral distortions such as baseline shifts, tilts, curvature, and scaling.

A Physical Framework to Interpret the Effects of High Permittivity Materials on Radiofrequency Coil Performance in Magnetic Resonance Imaging.

We propose a framework to interpret the effects of High Permittivity Materials (HPM) on the performance of radiofrequency coils in Magnetic Resonance Imaging (MRI). Based on a recent formulation of the scattering and propagation properties of spheres, we expanded the field in a layered sphere as a superposition of ingoing and outgoing travelling waves, which allowed us to study the field components with a non-homogeneous transmission line model. We investigated the effects of a layer of HPM surrounding a head-mimicking uniform sphere at 7 tesla. Through the analysis of impedance and reflection coefficients, we show that by adjusting the properties of the HPM, it is possible to selectively amplify individual modes, or combination of them, modifying the overall field distribution in the sample and increasing signal-to-noise ratio at specific locations. Our results demonstrate that the observed enhanced MRI performance is not merely due to secondary fields generated by displacement currents in the HPM. Our formulation explains the effect of HPM in terms of matching, enabling the optimization of the electrical properties of the HPM with a simple mode-matching formula. The proposed method could guide the design of novel radiofrequency coils with integrated HPM.

Excitation of a layered sphere by 𝑁 acoustic sources: Exact solutions, low-frequency approximations, and inverse problems

Acoustic excitation of a layered sphere by N N external and internal point sources is considered. The direct problem is solved by developing a T-Matrix method leading to the analytical determination of all the involved acoustic fields. Low-frequency far-field approximations are derived for different source distributions and scatterer’s characteristics. The behaviour of the scattering cross sections is investigated. Several inverse problems are formulated and solved analytically; thus the respective unknown quantities are recovered explicitly. These problems include localization of the sources, determination of their number, identification of the core’s type and extraction of the parameters of the scatterer’s layers.

The Stress Induced by the Epoxy Bonding Layer Changing in the Layered Hollow Spheres

In order to solve the problem of the instability of the layered hollow spherical structure caused by the epoxy bonding layer cracking, peeling and destruction, an exact analytical solution of the multi-layered hollow sphere with epoxy bonding layer under point load is obtained. The influence of the epoxy bonding layer change on the stress of the layered hollow sphere is studied by using the methods of analytical solution and numerical calculation. Numerical calculation results show that the stress of the bonded layered structure is affected by the Young’s modulus, Poisson’s ratio and the thickness of the bonding material without changing the overall size of the bonded layered hollow spheres. The use of the bonding materials can cause stress concentration at the bonding material interface. And the increase of Young’s modulus and the thinning of thickness of the bonding material can reduce the stress at the interface between the epoxy bonding layer and the outer layer. Moreover, the change of Poisson’s ratio of the bonding material cannot substantially reduce the interface stress. The research results provide theoretical guidance for the material selection and thickness setting of the bonding layer for layered hollow sphere.

Attenuation characteristics of Bessel Gaussian vortex beam by a wet dust particle

The potential applications of complex optical fields for environmental detection have attracted a lot of attention. In this study, dusty medium is equivalent to a uniformly charged sphere and a non-uniform concentric layered sphere that satisfying the single scattering condition, respectively. The interaction between a high-order polarized Bessel Gaussian beam and a spherical particle is investigated using the generalized Lorenz–Mie theory and the angular spectrum decomposition method. The location of incident beam is considered for the first time. The extinction efficiency results of a wet charged particle are compared with those of a wet neutral particle. Simulations show that the difference in extinction between these two kinds of particles mentioned above is more evident in the smaller size parameter range, which is similar to the case of plane wave incidence. In addition, the influence of complex refractive index and size proportion of heterogeneous medium on the extinction effect is analyzed. The characteristic parameters of the incident beam are considered and find out that how they affect the differences in extinction is independent of the illuminated particle. This study lays the foundation for analyzing the transmission capacity of a Bessel Gaussian vortex beam with various parameters in a dust particle cluster.

Bifunctional thioacetamide-mediated synthesis of few-layered MoOSx nanosheet-modified CdS hollow spheres for efficient photocatalytic H2 production

Few layered MoOSx nanosheet-decorated CdS hollow spheres have been rationally fabricated by a one-step bifunctional thioacetamide-mediated route to notably enhance the photocatalytic H2-production performance.

An integrated flexible film as cathode for High-Performance Lithium–Sulfur battery

Poor cycling stability and low volumetric capacity of sulfur cathode prevents practical application of Lithium-sulfur (Li-S) batteries. Herein, we demonstrate a strategy to address the two drawbacks of sulfur cathode by synthesizing a compact and flexible film cathode with bilayer structure using a two-step vacuum filtration method. Two layers make up the sulfur cathode, active layer (sulfur-acethlene black (SC) spheres) and barrier layer (three dimensional MnO2-graphene oxide-multi-walled carbon nanotubes (MnO2-GO-CNTs) composites), which are integrated together by reduced graphene oxide (rGO) through self-binding. The rGO sheets provide an electrical conductive framework and a stable architecture to accommodate volume changes of sulfur. SC spheres stacked orderly between the rGO layers facilitate fast Li+ storage and energy release. Polar MnO2-GO-CNTs composites with large specific surface area have not only afforded efficient sites for chemically binding polysulfides, but also provided fast electron transfer for accelerating polysulfides redox reaction. Consequently, the integrated film cathode exhibits an unprecedented cycling stability of ~0.0279% capacity decay per cycle over more than 600 cycles at 1C and high volumetric capacity of 1021.9 Ah L-1 at 2C. Meanwhile, a foldable Li-S battery based on this flexible cathode is fabricated and shows excellent mechanical and electrochemical properties. The integrated flexible sulfur cathode of this study sheds light on the design strategies for application in flexible high volumetric capacity system.

Determination of static thermoelastic state of layered thermosensitive plate, cylinder and sphere

Determination of static thermoelastic state of layered thermosensitive plate, cylinder and sphere

Enhanced Photothermal-Photodynamic Therapy by Indocyanine Green and Curcumin-Loaded Layered MoS2 Hollow Spheres via Inhibition of P-Glycoprotein.

PurposeP-glycoprotein (P-gp), which is highly expressed in liver cancer cells, is one of the obstacles for the treatment of cancer. In this study, we have prepared and characterized a kind of novel ICG&Cur@MoS2 (ICG and Cur represent indocyanine green and curcumin, respectively) nanoplatform, which can achieve photothermal-photodynamic therapy and inhibit the P-gp effectively and safely.MethodsIn this work, plenty of studies including drug release, acute toxicity, Western blot, real-time PCR, cell viability, therapeutic experiment in vivo, immunofluorescence and so on were conducted to test the antitumor potential of ICG&Cur@MoS2 and the inhibitory effect of curcumin on P-gp.ResultsThe ICG&Cur@MoS2 NPs exhibit an excellent photothermal effect and relatively low toxicity. Cell viability in the ICG&Cur@MoS2 + NIR group was significantly lower than that in ICG@MoS2 + NIR group (75.3% vs 81.2%, 59.0% vs 64.4%, 20.3% vs 27.5%, and 15.4% vs 22.3%) at the concentration of ICG at 0.5, 5, 25, 50 μg/mL (P<0.05 at each concentration). Western blot, Q-PCR, and immunofluorescence assay indicate ICG&Cur@MoS2 NPs can inhibit the P-gp effectively and safely. In vivo, the tumors in the ICG@MoS2 + NIR group are significantly smaller than those in the MoS2 + NIR group (95.0 vs 420.9 mm3, p<0.05).ConclusionIn conclusion, we have successfully synthesized ICG&Cur@MoS2 nanoparticles which can not only achieve PTT-PDT but also inhibit P-gp effectively. Our findings indicate that the PTT-PDT exhibits great potential in the treatment of hepatocellular carcinoma. Meanwhile, ICG&Cur@MoS2 can effectively inhibit the expression of P-gp, which will enhance the PDT effect.

Acoustic Vibration of Hexagonal Nanoparticles With Damping and Imperfect Interface Effects

Abstract In this paper, acoustic vibration of hexagonal nanoparticles is investigated. In terms of the spherical system of vector functions, the first-order differential equation with constant coefficients for a layered sphere is obtained via variable transformation and mass conservation. The propagation matrix method is then used to obtain the vibration equation in the multilayered system. Further utilizing a new root-searching algorithm, the present solution is first compared to the existing solution for a uniform and isotropic sphere. It is shown that, by increasing the sublayer number, the present solution approaches the exact one. After validating the formulation and program, we investigate the acoustic vibration characteristics in nanoparticles. These include the effects of material anisotropy, damping, and core–shell imperfect interface on the vibration frequency and modal shapes of the displacements and tractions.

Implementing radial anisotropy with self-similar structures

Radial anisotropy in small objects has been linked to exotic optical properties. It can be implemented with a spherical inclusion that manifests self-similarity. We show that, when a self-similar, onion-like structure with alternating layers is homogenized by using an effective material approximation, the homogenized material becomes uniaxially anisotropic with the axis of anisotropy pointed radially outward from the center of the inclusion. This radial anisotropy becomes exact in the limit of a dense set of layers. The exact equivalence of the layered self-similar inclusion and the radially anisotropic inclusion manifests itself both in the effective permittivities of the two inclusions---when homogenized over the entire volumes---and in the internal potentials. Because the layered sphere and the radially anisotropic sphere are analogous, it is possible to study some of the interesting scattering features of radially anisotropic spheres in a realistic configuration. In particular, we show that the outcome of homogenizing the self-similar inclusion, and consequently the electric response, depends on what the core material at the center of the inclusion is and that a continuous transition between the two homogenization models is possible. The findings suggest intriguing applications in nanophotonics.

Dyadic Green's function for the electrically biased graphene-based multilayered spherical structures

Dyadic Green's function for a multilayered spherical structure with alternating graphene-dielectric shells is extracted in this paper. To this end, the unknown expansion coefficients of the scattering superposition method are obtained by considering graphene local surface currents at the interface of two adjacent layers. To validate the formulas, the procedure of Mie scattering analysis employing our formulas is clarified and the extinction efficiencies of various graphene-based nanoparticles are computed. The possibility of using the proposed structure in the design of multi-band optical absorbers is discussed in detail. Moreover, a closed-form formula for obtaining the Purcell factor of a radial dipole emitter in the presence of a graphene-based layered sphere is introduced. The analysis is followed by an example illustrating the possibility of dual-band enhancement of the Purcell factor using a graphene-based core-shell particle. Finally, the procedure of calculating the energy transfer between the donor-acceptor pairs with arbitrary locations are clarified. The research can be potentially used in the fast and efficient analysis of a wide class of novel optical devices with the arbitrary source of excitation.

H2 production from methane decomposition by fullerene at low temperature

Carbon materials have previously been reported to work as catalysts for hydrogen (H2) production from hydrocarbons. Mechanisms of the catalytic behavior of graphite and carbon black (CB) have often been discussed in literature. Graphite and CB is constructed from mainly 6-membered rings with sp2 bonds. To understand the catalytic behavior of carbon materials for H2 production by methane (CH4) decomposition, the catalytic behavior of fullerenes with 6-membered rings and also those comprising 5- and 7-membered rings with sp2 bonds and their associated mechanisms should be investigated. In this study, the fullerene catalyst activity has been investigated using gas chromatography and the electronic states and nanoscale structures have been analyzed.H2 production started at 400 °C and the H2 production rate gradually increased with time, and the activation energy of the fullerene for H2 production by CH4 decomposition was found to be 166 kJ/mol. Moreover, in situ heating X-ray photon spectroscopy (XPS) measurements showed that the π-π∗ transition signal becomes stronger with increasing temperature above the threshold of 300 °C. The transition of the π electrons to π∗ orbitals upon heating is expected to decompose CH4 absorbed on fullerene. Moreover, transmission electron microscopy (TEM) analysis revealed that the generated carbon atoms from the CH4 decomposition were deposited onto the surfaces of the fullerenes, forming amorphous and layered concentric sphere carbon. Amorphous carbon is reported to not work as a catalyst for CH4 decomposition at around 400 °C. From XPS analysis and TEM observations of these two structures, it is anticipated that the ring structures without 6-membered rings in carbon materials with sp2 bonding contribute to this catalytic behavior for CH4 decomposition at a low temperature of 400 °C.