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The rough structure may affect the flow field and electromagnetic (EM) scattering characteristics of a hypersonic vehicle. In this study, the EM scattering characteristics of the hypersonic vehicle RAM C-II with a microrough surface were investigated in the millimeter wave band. We first simulated the flow field of a smooth RAM C-II vehicle and calculated the radar cross section (RCS) in the wideband using the physical optics method. The calculation results show that many factors contribute to the variation in the RCS; however, it is occasionally difficult to predict. We then used a one-dimensional Gaussian random rough surface to generate a RAM C-II with a microrough surface through a point-coordinate transformation and simulated its flow field. The electron density flow field of the rough surfaced aircraft fluctuates greatly on the wall. Finally, we calculated the RCS of RAM C-II with different values of roughness in the millimeter wave band. The change of surface structure can be reflected in millimeter waves, and the RCS is determined by both plasma and rough structure. [ABSTRACT FROM AUTHOR]

Plasma shock waves represent high-speed, nonlinear motion states of plasma in which the physical parameters of fluid, such as density, temperature, and velocity, vary dramatically within a limited space. These variations make studying electromagnetic wave propagation in plasma shock waves difficult. In this study, we calculate the spatial distribution of the plasma frequency and collision frequency in the plasma shock layer based on the one-dimensional structure of the plasma shock wave. In the process from upstream to downstream of the plasma shock wave, the plasma frequency increases as a function of electron density; downstream, the plasma frequency increases as a function of the free stream Mach number, while the collision frequency decreases first and then increases. We also use the recursive convolution finite-difference time-domain method to calculate the propagation of the electromagnetic wave in the plasma shock layer. The absorption of the plasma shock layer to the electromagnetic wave decreases gradually as a function of the electromagnetic wave frequency. The absorption of the plasma shock layer downstream of the electromagnetic wave is greater than that upstream owing to the larger plasma frequency. In the case of low-Mach numbers, the wavelength of the electromagnetic wave downstream is larger than that upstream. In the case of high-Mach numbers, the thickness of the entire shock layer is much greater than that at low-Mach numbers. Due to the nonlinear effects of electromagnetic processes in plasmas, a modulation phenomenon occurs when electromagnetic waves propagate in the shock layer. In the case of low frequencies, the electromagnetic wave gave rise to a modulation phenomenon that resembled the beat phenomenon. When the electromagnetic wave frequency increased, a modulation phenomenon gradually appeared that resembled the oscillation superimposed on a sine wave. Further increases in the electromagnetic wave frequency led to the gradual disappearance of the modulation phenomenon. [ABSTRACT FROM AUTHOR]

Backgrounds: Freezing of gait (FOG) and cognitive impairment are serious symptoms of Parkinson's disease (PD). Understanding the association between FOG and cognition may help formulate specific interventions for PD individuals. Objectives: We aimed to investigate the associations of cognitive impairment in different domains with FOG status using multiple neuropsychological tests. Methods: Two cohorts including 691 and 104 participants were recruited from Parkinson's progression markers initiative (PPMI) and central China, respectively. All participants underwent FOG assessment and neuropsychological tests, and 595 individuals from PPMI and 51 from central China were enrolled for longitudinal observation. Cross-sectional and longitudinal associations between cognition and FOG status were evaluated using multivariable-adjusted models. Results: Worse cognitive performances were observed in patients with FOG compared to those without FOG in both cohorts (β = − 0.020, p < 0.001) using multivariate-adjusted models. Moreover, patients with progressive FOG during follow-up manifested more serious cognitive declines (HR = 1.40, 95% CI = 1.07–1.80). The FOG was mainly associated with the decline of executive, attention, and orientation. Furthermore, FOG was associated with higher levels of cognition-related biomarkers including T-tau, P-tau, and NfL in cerebrospinal fluid (p < 0.050). Conclusions: FOG is a risk factor for cognitive decline in PD, which emphasizes the need for early detection and monitoring of cognitive changes and interventions on cognitive impairments in PD patients with FOG. [ABSTRACT FROM AUTHOR]

This paper introduces the propagation properties and polarization characteristics of radially polarized partially coherent vortex beams in anisotropic plasma turbulence and discusses in detail the distribution of light intensity in such beams as a function of propagation distance. In addition, we analyze how the parameters of the anisotropic plasma turbulence affect the degree of polarization, polarization orientation angle, and degree of ellipticity of the beam. The results show that the degree of polarization of the radially polarized partially coherent vortex beam satisfies the modification of the central origin zero and the gradual increase with the radius during plasma turbulent propagation. At the same time, smaller turbulence eddies in the anisotropic plasma turbulence render, more obvious the irregular structure perpendicular to the vortex-stretching direction, the smaller the influence on the polarization characteristics of the radially polarized partially coherent vortex beam. It is advantageous to the research on optical communication and the study of anisotropic plasma turbulence. [ABSTRACT FROM AUTHOR]

A new electromagnetic (EM) calculation model, the inhomogeneity zonal medium model (IZMM) (based on the physical optics (PO) method), is proposed to calculate and analyze the EM scattering characteristics of hypersonic vehicle covered with a plasma sheath. First, the flow field of the plasma sheath is divided into nonuniform calculation subregions with different spacing sizes. The shape of the external flow field of the aircraft is modeled by fitting with a paraboloid and circular platform with different radii. Then, the electron density, temperature, and pressure distribution are obtained by collecting data from different points in the flow field of the sheath. Finally, a piecewise PO method is used to calculate the backscattering radar cross section (BRCS) of the hypersonic vehicle covered with plasma sheath from $L$ -band to $X$ -band. The numerical results show that the EM scattering characteristics of a target spacecraft covered with a plasma sheath can be described more accurately by using zoned medium model simulation. Under different flying conditions, the BRCS of hypersonic vehicle covered with a plasma sheath appears to be reduced to different degrees in the $S$ -band and the band range of 7–11 GHz, and a large attenuation of BRCS occurs in the head area of the aircraft. The research results enrich the EM modeling method of hypersonic vehicles, overcome some shortcomings of the existing PO method, and provide technical support and innovative ideas for the accurate analysis of the EM scattering characteristics of hypersonic targets. [ABSTRACT FROM AUTHOR]

To investigate the electromagnetic scattering problem related to a foil in a turbulent hypersonic plasma environment, the scattering field formulas for hypersonic plasma turbulence were improved by applying the anisotropic power spectrum. Using the theory of electromagnetic scattering of a conducting object, the second moment of a conducting object's scattering field is obtained in the hypersonic plasma turbulence. Finally, the backscattering cross-section of the foil surrounded by the hypersonic plasma turbulence was calculated. The results showed that the fractal dimension led to an increase in the complexity of the hypersonic turbulent structure, and thus had a greater influence on the electromagnetic wave scattering. The scattering cross-section of the foil in the hypersonic turbulence decreases rapidly. Meanwhile, the anisotropic parameters in the model represent scale-dependent stretching of the turbulent eddy. As the anisotropic parameters of the turbulence increase, there will be less scattering of the hypersonic turbulence. At this point, the total scattering cross-section of the foil in hypersonic plasma turbulence increases gradually. By improving the aerodynamic shape of the aircraft, it can produce a large number of anisotropic turbulent eddies which can effectively improve the passive jamming capability when the foil is cast. [ABSTRACT FROM AUTHOR]

On the basis of the fractal theory and measurements of hypersonic turbulence, the spectral index, and twodimensional (2D) power spectrum of the refractive index fluctuation are derived, and the 2D band-limited Weierstrass fractal function is applied to simulate the refractive index fluctuation in hypersonic turbulence. Thus, the impact of hypersonic turbulence on synthetic aperture radar (SAR) imaging system is simulated using the fractal phase screen method. Results show that the resolution of SAR imaging is severely deteriorated under the influence of hypersonic turbulence. The phase error caused by the turbulence microstructures in the plasma sheath becomes more apparent with the increase in the fractal dimension of the hypersonic turbulence. The larger Reynolds number associated with the hypersonic turbulence results in a more evident microstructure fluctuation and inferior imaging quality. Furthermore, when an aircraft flies at high speed, the azimuth focus is considerably sensitive to the turbulence microstructure along the direction of flow field. Consequently, hypersonic turbulence in the plasma sheath has a significantly larger effect on the azimuth than on the range in point-target imaging. [ABSTRACT FROM AUTHOR]

Anisotropic spatial distribution data of refractive-index fluctuation in hypersonic turbulence are obtained based on the experimental images of hypersonic turbulence. Furthermore, taking re-entry turbulent plasma fluctuation into consideration, the variance of the refractive-index fluctuation in hypersonic plasma is calculated based on the Saha equation and the expression of refractive index in hypersonic plasma. On this basic, the anisotropic power-spectral model of hypersonic plasma turbulence is established by introducing the orientation factor to the modified von Karman spectrum. Finally, the mutual coherence function (MCF) and the angle-of-arrival fluctuations of electromagnetic (EM) waves propagation in hypersonic plasma turbulence are calculated. Results show that the angle-of-arrival fluctuations have obvious differences between the directions of vertical to turbulent plasma flow field and parallel to it. The various gradients of the electron density along the direction of vertical to turbulent plasma flow field are far greater than the parallel to it, which causes the horizontal scale is larger than perpendicular scale of plasma eddies. Therefore, when EM waves propagating through plasma turbulence, the refractive effect of plasma eddies show obvious anisotropy. The results of this paper can be used to analyze the EM waves propagation characteristics in hypersonic plasma turbulence. [ABSTRACT FROM PUBLISHER]

Based on the power spectrum of the refractive-index fluctuation in the plasma sheath turbulence, the expressions for wave structure functions and scintillation index of optical wave propagating in a turbulent plasma sheath are derived. The effect of the turbulence microstructure on the propagation characteristics of optical waves are simulated and analyzed. Finally, the bit error performance of a free-space optical (FSO) link is investigated under the effect of plasma sheath turbulence. The results indicate that the spherical waves have a better communication performance in the FSO link. In addition, a greater variance of the refractive index fluctuation causes a more severe fluctuation in electron density, temperature, and collision frequency inside the plasma sheath. However, when the outer scale is close to the thickness of the plasma sheath, the turbulence eddies have almost no influence on the wave propagation. Therefore, the bit error rate (BER) obviously increases with the increase in variance of the refractive index fluctuation and the decrease in the outer scale. These results are fundamental for evaluating the performance of the FSO link under the effect of plasma sheath turbulence. [ABSTRACT FROM AUTHOR]

The interaction mechanism between plasmas and electromagnetic waves has not been fully defined, and experiments are helpful for investigating the mechanism and verifying the theoretical analysis. This paper proposes a point-focusing lens antenna based on three-dimensional (3D) printing technology for the experimental study of the interaction between electromagnetic waves and a small-area plasma. First, CST simulation software was used for the simulation design of the horn antenna and focusing lens. Subsequently, 3D printing technology was used to print the lens combined with the horn antenna for experimental verification of the focusing performance. Finally, an electromagnetic wave passing through a plasma was experimentally investigated, and it was mutually verified with the propagation theory of electromagnetic waves in plasmas. The experimental and theoretical data indicated that the 3D-printed point-focusing lens antenna exhibited a good focusing effect on electromagnetic waves. This method may be used by employing a variety of materials and designs, thereby considerably improving the detection of small-area plasma. It may also solve the issue of the radial diffraction effect of narrow cylindrical plasma generated by inductively coupled plasma-generation equipment and reduce the error associated with experimental data. Therefore, this method may be useful for plasma propagation measurement, plasma-environment diffraction analysis, and parameter inversion of complex plasma environments. [ABSTRACT FROM AUTHOR]

We demonstrated an asymmetric 1,3-dipolar cycloaddition of azomethine betaines with alkylidene malonates by using a chiral N, N′-dioxide-NiII complex as a catalyst. Both aromatic- and aliphatic-substituted alkylidene malonates were found to be suitable for the reaction. A range of trans-pyrazolone derivatives was exclusively obtained with excellent yields (up to 99 % yield) and good enantioselectivities (up to 97 % ee) under mild reaction conditions. The reaction could be carried out on a gram scale with the good results being maintained. Control experiments were performed to elucidate the specific diastereoselectivity of the reaction. The formation of single trans isomers was dominated by secondary orbital interactions between the ester groups of the dipolarophile and the azomethine imine. On the basis of the experimental results and previous reports, a possible catalytic model was assumed. [ABSTRACT FROM AUTHOR]

Dusty plasma environments, such as aircraft sheaths and rocket exhaust plumes, significantly affect the propagation of electromagnetic (EM) waves. In this study, the Mie theory and the dyadic Green method were used to calculate the Mie scattering cross section, Debye scattering cross section of the surrounding Debye cloud, and Mie–Debye coherence cross section formed by the two scattering fields. We propose that the Mie–Debye model should be regarded as a whole particle, and the dusty plasma can be simplified by assuming that it is composed of Mie–Debye spherical models of different densities. These assumptions were combined with the scattering characteristics of the microscopic Mie–Debye model and Monte Carlo method to analyze the propagation characteristics of EM waves in dusty plasma. [ABSTRACT FROM AUTHOR]

Based on the detection platform of space-borne radar (SBR), the dynamic electromagnetic (EM) scattering characteristics of a hypersonic vehicle covered with plasma sheath are calculated and analyzed by the physical optics (PO) method. Using the angle-time conversion method, the dynamic radar cross section (DRCS) of the vehicle in horizontal flying path and different flying states is solved in the range of L-band to X-band. The relevant effective statistical features are extracted from the time-scale matrix of DRCS based on continuous wavelet transform (CWT). The numerical results show that: At different flying altitudes, the backscattering radar cross section (BRCS) of the hypersonic vehicle covered with plasma sheath has irregular fluctuation and large range reduction in the head region of the vehicle. Generally, the higher the incident EM wave frequency is, the more detailed the fluctuation characteristics of the DRCS can be reflected. Within the same radar illuminate angle range, the time consumed by the vehicle DRCS is inversely proportional to the flying height and flying speed and is directly proportional to the detection altitude of the SBR. Besides, the different kinds of statistical eigenvalues extracted from DRCS will play an important role in hypersonic targets classification and recognition. [ABSTRACT FROM AUTHOR]

During reentry, the high temperatures experienced by near-space hypersonic vehicles result in surface ablation, generating ablative particles. These particles become part of a plasma, commonly referred to as a "dusty plasma sheath" in radar remote sensing. The dusty plasma model, integral in radar studies, involves extensive charge and dynamic interactions among dust particles. Previous derivations assumed that the dust particle radius significantly surpassed the Debye radius, leading to the neglect of dust radius effects. This study, however, explores scenarios where the dust particle radius is not markedly smaller than the Debye radius, thereby deducing the charging process of dusty plasma. The derived equations encompass the Debye radius, charging process, surface potential, and charging frequency, particularly considering larger dust particle radii. Comparative analysis of the dusty plasma model, both before and after modification, reveals improvements when dust particles approach or exceed the Debye length. In essence, our study provides essential equations for understanding dusty plasma under realistic conditions, offering potential advancements in predicting electromagnetic properties and behaviors, especially in scenarios where dust particles closely align with or surpass the Debye radius. [ABSTRACT FROM AUTHOR]

The attenuation characteristics of obliquely incident electromagnetic (EM) wave in L-Ka frequency band in weakly ionized dusty plasma are analyzed based on the modified Bhatnagar–Gross–Krook (BGK) collision model. According to the kinetic equation and the charging theory, the total complex dielectric constant of the weakly ionized dusty plasma is derived by considering that the minimum velocity of the electron accessible to the dust particle surface is non-zero and the second potential part of the collision cross-section contributes to the charging. The attenuation characteristics within the modified model are compared with those within the traditional model. The influence of the dusty plasma parameters and the incident angle of EM waves on the attenuation in weakly ionized dusty plasma is further analyzed. Finally, the influence of different reentry heights on the attenuation characteristics of the obliquely incident EM wave is discussed. The results show that the effect of the minimum electron velocity and the second term of the collision cross-section on the attenuation characteristics of EM waves cannot be ignored. When the dust density and dust radius are changed, the trends of the attenuation of obliquely incident EM waves are consistent, but the influence of dust density is weaker than that of dust radius due to the constraint of orbit-limited motion (OLM) theory. The plasma thickness, electron density, and incident angle are proportional to the attenuation amplitude of EM waves. The effect of different reentry heights on the attenuation obliquely incident EM waves is related to the electron density and plasma thickness. [ABSTRACT FROM AUTHOR]

Background: Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic (DA) neurons in the substantia nigra (SN). Microglia-mediated neuroinflammation has been largely considered one of main factors to the PD pathology. MicroRNA-218-5p (miR-218-5p) is a microRNA that plays a role in neurodevelopment and function, while its potential function in PD and neuroinflammation remains unclear. Methods: We explore the involvement of miR-218-5p in the PD in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model. The miR-218-5p agomir used for overexpression was delivered into the substantia nigra (SN) by bilateral stereotaxic infusions. The loss of dopaminergic (DA) neurons and microglial inflammation in the SN was determined using Western blotting and immunofluorescence. Motor function was assessed using the rotarod test. RNA sequencing (RNA-seq) was performed to explore the pathways regulated by miR-218-5p. The target genes of miR-218-5p were predicted using TargetScan and confirmed using dual luciferase reporter assays. The effects of miR-218-5p on microglial inflammation and related pathways were verified in murine microglia-like BV2 cells. To stimulate BV2 cells, SH-SY5Y cells were treated with 1-methyl-4-phenylpyridinium (MPP+) and the conditioned media (CM) were collected. Results: MiR-218-5p expression was reduced in both the SN of MPTP-induced mice and MPP+-treated BV2 cells. MiR-218-5p overexpression significantly alleviated MPTP-induced microglial inflammation, loss of DA neurons, and motor dysfunction. RNA sequence and gene set enrichment analysis showed that type I interferon (IFN-I) pathways were upregulated in MPTP-induced mice, while this upregulation was reversed by miR-218-5p overexpression. A luciferase reporter assay verified that Ddx41 was a target gene of miR-218-5p. In vitro, miR-218-5p overexpression or Ddx41 knockdown inhibited the IFN-I response and expression of inflammatory cytokines in BV2 cells stimulated with MPP+-CM. Conclusions: MiR-218-5p suppresses microglia-mediated neuroinflammation and preserves DA neurons via Ddx41/IFN-I. Hence, miR-218-5p-Ddx41 is a promising therapeutic target for PD. [ABSTRACT FROM AUTHOR]

Highlights • Propagation model of radially polarized vortex beams in atmospheric turbulence is established. • A radially polarized vortex beam can reduce beam spreading and wander effects in the atmosphere. • Polarization modulation can be an approach to mitigate turbulent effects on OAM-based systems. Abstract Adopting a vortex beam with poor coherence can reduce turbulence-induced beam spreading and wander effects in the atmosphere, but it intensifies the degradation rate of its beam profile from a doughnut shape into a Gaussian shape. Transmission quality of Orbital–angular–momentum (OAM) mode carried by a vortex beam is closely related to its evolution of intensity distribution. After appropriate polarization modulation, a radially polarized vortex beam has a better performance on the reduction of beam spreading and wander effects than its scalar counterpart. A radially polarized vortex beam can also lower the degradation rate of its beam profile and keep "OAM information" a longer distance. Therefore, appropriate polarization modulation can be an effective approach to mitigate the adverse turbulent effects on OAM-based systems operated in the atmosphere. [ABSTRACT FROM AUTHOR]

Analytical expressions of average intensity and long-term beam width for a radially polarized multi-Gaussian Schell-model (MGSM) beam in anisotropic atmospheric turbulence are developed based on the extended Huygens-Fresnel principle. The influences of anisotropic non-Kolmogorov turbulence and source parameters on the average intensity, polarization and long-term beam spreading of radially polarized MGSM beam are examined in detail. The source correlations, free-space diffraction and turbulent effect jointly affect both the intensity and polarization profiles of the beam propagated in the atmosphere. As a radially polarized MGSM beam propagates in the atmosphere, increasing the associated beam order can lower the evolution rate from its flat-topped beam profile into a Gaussian beam profile because of the turbulent effect. Variations in the average intensity and long-term beam width are closely related to the propagation distance, power spectrum index, inner-scale, initial spatial coherence, and beam width. The atmospheric turbulence-induced beam spreading is generally suppressed with the enhanced anisotropy coefficient. [ABSTRACT FROM AUTHOR]

The influences of source parameters, non-Kolmogorov and anisotropic turbulence on the beam spreading and beam wander of electromagnetic Multi-Gaussian Shell-model (EMGSM) beams in the atmosphere with aberration correction were analyzed. Zernike tilt aberration correction method had more effect on beam spreading compared to beam wander. Increasing the anisotropic property of turbulence could degrade both beam spreading and beam wander. EMGSM beams with larger beam order, wavelength could better mitigate the turbulence effects than GSM beams, which could be adopted as a better light source with several adjustable parameters to lower scintillation and beam wander in free-space optical communication. [ABSTRACT FROM AUTHOR]

Optimized conditions render possible the preparation of various pyrazolidinone derivatives as important substructures. [ABSTRACT FROM AUTHOR]

[Display omitted] • α-Syn level and UPDRS-III scores were positively correlated with the increase in Th17 cells and decrease in Tregs. • α-Syn led to the loss of FOXP3 in Tregs, accompanied by the acquisition of IL-17A. • α-Syn stimulation induced Th17 differentiation when naïve CD4+ T cells were under Th17-polarizing conditions. • α-Syn promotes the transcription of RORC , leading to increased Th17 differentiation and loss of Treg function. • Inhibition of RORγt alleviated the Th17/Tregs imbalance and apoptosis of DA in PD mice. Parkinson's disease (PD) is characterized by the loss of dopaminergic neurons (DA) and the accumulation of Lewy body deposits composed of alpha-Synuclein (α-Syn), which act as antigenic epitopes to drive cytotoxic T -cell responses in PD. Increased T helper 17 (Th17) cells and dysfunctional regulatory T cells (Tregs) have been reported to be associated with the loss of DA in PD. However, the mechanism underlying the Th17/Treg imbalance remains unknown. Here, we examined the percentage of Th17 cells, the percentage of Tregs and the α-Syn level and analysed their correlations in the peripheral blood of PD patients and in the substantia nigra pars compacta (SNpc) and spleen of MPTP-treated mice and A53 transgenic mice. We assessed the effect of α-Syn on the stability and function of Tregs and the differentiation of Th17 cells and evaluated the role of retinoid-related orphan nuclear receptor (RORγt) upregulation in α-Syn stimulation in vivo and in vitro. We found that the α-Syn level and severity of motor symptoms were positively correlated with the increase in Th17 cells and decrease in Tregs in PD patients. Moreover, α-Syn stimulation led to the loss of Forkhead box protein P 3 (FOXP3) expression in Tregs, accompanied by the acquisition of IL-17A expression. Increased Th17 differentiation was detected upon α-Syn stimulation when naïve CD4+ T cells were cultured under Th17-polarizing conditions. Mechanistically, α-Syn promotes the transcription of RORC , encoding RORγt, in Tregs and Th17 cells, leading to increased Th17 differentiation and loss of Treg function. Intriguingly, the increase in Th17 cells, decrease in Tregs and apoptosis of DA were suppressed by a RORγt inhibitor (GSK805) in MPTP-treated mice. Together, our data suggest that α-Syn promotes the transcription of RORC in circulating CD4+ T cells, including Tregs and Th17 cells, to impair the stability of Tregs and promote the differentiation of Th17 cells in PD. Inhibition of RORγt attenuated the apoptosis of DA and alleviated the increase in Th17 cells and decrease in Tregs in PD. [ABSTRACT FROM AUTHOR]

3-D time-varying and spatially nonuniform plasma is applied using the finite-difference time-domain algorithm in investigating the effects of electromagnetic (EM) wave scattering in the plasma sheath. The plasma sheath is stratified in space, and three types of electron density in time-varying forms are assumed. The characteristics of different time-varying forms are analyzed using radar cross section (RCS). In addition, the effects of RCS change with time at S - and L -bands are investigated using electron density as the time variable. In the condition of time-varying and spatially nonuniform plasma sheath, the attenuation of EM wave is affected by different time-varying regularities of electron density ( ne ). The RCS varying with time is related to the change rate of ne . [ABSTRACT FROM PUBLISHER]

In this paper, we obtain the intensity and phase distributions of the scattering and external fields of a vector Bessel–Gaussian vortex beam in the far-field region after being scattered by a particle. In our analysis, we use the Generalized Lorenz–Mie theory (GLMT) and the angular spectrum decomposition method (ASDM). The orbital angular momentum (OAM) spectra of the fields are analyzed by using the spiral spectrum expansion method, which is a frequently used tool for studying the propagation of vortex beams in turbulent atmospheres. Both scattered and external fields show a significant difference in spiral spectra for particles with different characteristic parameters, such as the size and complex refractive index. We also examine sampling the phase along with a circle and show that it is unable to fully express the information of the fields. This study can provide a theoretical basis for the inversion of characteristic parameters of the Bessel–Gaussian vortex beam and spherical particle by OAM spectra with applications in remote sensing engineering. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a highly prevalent cancer with a significant impact on human health. Curcumin, a natural compound, induces cytoskeletal changes in liver cancer cells and modifies the distribution of lipids, proteins, and polysaccharides on plasma membranes, affecting their mechanical and electrical properties. In this study, we used nanomechanical indentation techniques and Kelvin probe force microscopy (KPFM) based on atomic force microscopy (AFM) to investigate the changes in surface nanomechanical and electrical properties of nuclear and cytoplasmic regions of HepG2 cells in response to increasing curcumin concentrations. CCK-8 assays and flow cytometry results demonstrated time- and concentration-dependent inhibition of HepG2 cell proliferation by curcumin. Increasing curcumin concentration led to an initial increase and then decrease in the mechanical properties of nuclear and cytoplasmic regions of HepG2 cells, represented by the Young's modulus (E), as observed through nanoindentation. KPFM measurements indicated decreasing trends in both cell surface potential and height. Fluorescence microscopy results indicated a positive correlation between curcumin concentration and phosphatidylserine translocation from the inner to the outer membrane, which influenced the electrical properties of HepG2 cells. This study provides valuable insights into curcumin's mechanisms against cancer cells and aids nanoscale evaluation of therapeutic efficacy and drug screening. • We accurately measured Young's modulus of living HepG2 cells under curcumin inhibition using PS microsphere modified AFM. • We demonstrated a correlation between Young's modulus and concentration of curcumin utilizing AFM nanomechanical analyses. • Relation between electrical properties of HepG2 cells and phosphatidylserine translocation in apoptosis was found by KPFM. [ABSTRACT FROM AUTHOR]

In this study, new expressions for wave structure functions (WSFs) for optical planes and spherical waves propagating in plasma turbulence are derived based on the refractive index undulation power spectrum of hypersonic plasma turbulence and Rytov approximation theory. On this basis, the mathematical expressions for plasma turbulence modulation transfer function (MTF) for optical planes and spherical waves are obtained using WSF expression. The mathematical expressions describe the attenuation effect of plasma turbulence on optical imaging systems. The effects of different wavelengths, turbulent outer scales, and refractive index undulation variance on plasma turbulence MTF were calculated and analyzed. Results show that increasing the incident wavelength reduces the effect of plasma turbulence on the imaging system. Moreover, increasing the turbulence outer scale and reducing the refractive index undulation variance can also improve the imaging results. [ABSTRACT FROM AUTHOR]

Electron density is one of the most important parameters for characterizing plasma properties, so obtaining accurate electron density is a prerequisite for studying the interaction between plasma and the electromagnetic waves. This paper presents the effects of different electron densities on the electric field distribution of a microstrip antenna with a center frequency of 2.45 GHz. Then, on the basis of the integrated model of plasma and the microstrip antenna, the Bayesian regularization neural network (BRNN) is used to retrieve the electron density of inhomogeneous plasma. Furthermore, the performance of the proposed approach is evaluated and analyzed by comparison with Levenberg–Marquardt (LM) and Scaled Conjugate Gradient (SCG) neural networks. The results show that the BRNN provides better performance than LM and SCG neural networks to retrieve plasma electron density based on the electric field intensity at fewer spatial positions. The accurate distribution of the electron density of inhomogeneous plasma can be obtained using BRNN. In addition, the greater the range variation of electron density, the greater the relative inversion error. This study provides an important theoretical basis for the diagnosis of electron density for inhomogeneous plasma in experiments. [ABSTRACT FROM AUTHOR]

The effects of nonuniform moving plasma on the polarization properties of electromagnetic (EM) waves were theoretically studied. Taking the ${L}$ -band right-hand circularly polarized (RHCP) wave as an example, based on the nonuniform moving plasma slab moving perpendicularly to the incident wave, the relationship between the polarization properties of the transmitted wave and the normalized velocity of the nonuniform plasma slab was analyzed. The results indicate that the polarization state of the transmitted wave is closely related to the normalized velocity of the nonuniform plasma slab. When the plasma slab approaches to the incident wave, its influence on the polarization properties is greater than that away from the incident wave. In addition, when the change of the polarization state reaches the maximum, the corresponding normalized velocity is mainly determined by the incident angle and the collision frequency. Various interesting features regarding polarization properties were obtained. The results are very important for applications in space exploration. [ABSTRACT FROM AUTHOR]

The influence of weakly ionized dusty plasma on electromagnetic (EM) wave propagation was investigated to understand blackouts in communications during the reentry of hypersonic vehicles. Adopting the Bhatnagar–Gross–Krook (BGK) collision model and charging theory, the total complex dielectric constant of weakly ionized dusty plasma is derived considering solely: 1) a nonzero minimum velocity of the electron; 2) a contribution of the second term of the collision cross-section; and finally, 3) both 1) and 2) considered. Using the propagation matrix method, we analyzed the dielectric constant and propagation properties from our modified models and those of the traditional model for weakly ionized plasma with and without dust. The results show that, regarding EM waves, the dust-free weakly ionized plasma has a larger coefficient of reflection than weakly ionized dusty plasma. Simultaneous considering nonzero velocity and contribution of the second term of the collision cross-section significantly changed the dielectric constant and propagation properties, indicating the nonnegligible role of these two factors. Furthermore, the influence of dust size and concentration on the propagation properties of the EM wave was discussed with considering the two factors. The simulated results show that the coefficient of absorption increases and the coefficient of transmission decreases with increase in size and concentration of dust particles. [ABSTRACT FROM AUTHOR]

In order to study the electromagnetic wave transmission characteristics in seawater under external physical effects, we present a study of seawater ionic solution and perform a theoretical basis of magnetic field on water molecules and ionic motion to investigate the variation of dielectric properties with frequency under static magnetic field (0.38 T). Seawater is a naturally multi-component electrolyte solution, the main ingredients in seawater are inorganic salts, such as NaCl, MgSO4, MgCl2, CaCl2, KCl, NaHCO3, etc. The dielectric properties of these electrolyte solutions with different salinity values (0.01-5%) were measured in frequencies ranging from 40 to 5 MHz at 12C. The results show that the dielectric constant decreases with increasing frequencies no matter with magnetic field or without it. Frequency dependence of the dielectric constant of NaCl solution increases under magnetic field at measure concentrations. In a solution of MgCl2 ⋅ 6H2O, KCl and NaHCO3 are consistent with NaCl solution, while CaCl2 ⋅ 2H2O solution is in contrast with it. We also find that dielectric loss plays a major role in complex permittivity. With the effect of magnetic field, the proportion of dielectric loss is reducing in complex permittivity. On this basis it was concluded that the magnetic field influences the orientation of dipoles and the variation is different in salt aqueous solution. [ABSTRACT FROM AUTHOR]

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. • The attenuation characteristics of a high-order polarized Bessel Gaussian beam by a uniformly charged sphere and a non-uniformly concentric sphere are studied for the first time. • The influence of the position of the incident beam on the attenuation effect is discussed. • The difference in extinction between charged and neutral particles is more evident in the smaller size parameter range, which is similar to the case of plane wave incidence. [ABSTRACT FROM AUTHOR]

Abstract: The chiral N,N′-dioxide–Yb(OTf)3 complex-catalyzed enantioselective aza-Diels–Alder reaction of Brassard’s diene with aldimines has been developed, giving the corresponding α,β-unsaturated δ-lactam derivatives in moderate yields with good enantioselectivities (up to 81% ee and up to 99% ee by single recrystallization) under mild conditions. Isolation of the reaction intermediate indicates that this asymmetric aza-Diels–Alder reaction proceeds through a stepwise Mannich-type pathway. [Copyright &y& Elsevier]

• The aging behavior of HSMB and LSMB under heat and UV were investigated. • The microstructure and chemical structure of HSMB and LSMB were analyzed. • The aging reaction rate and activation energy of LSMB and HSMB were studied. In this paper, the aging behavior of high dosage styrene–butadienestyrene (SBS) modified bitumen (HSMB) for waterproof materials and low dosage SBS modified bitumen (LSMB) for pavement were investigated. The effects of heat as well as ultraviolet-heat synergism on properties and chemical structure of HSMB and LSMB were evaluated by physical properties, fluorescence microscope (FM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the change of softening point and low temperature flexibility of HSMB was much less than that of LSMB after heat aging, which indicated that the aging resistance of HSMB was better than that of LSMB. The physical properties changes of HSMB and LSMB after UV-heat synergism aging were much serious than that of HSMB and LSMB after heat aging. FM indicated that HSMB showed the network structure, and its structure was only partially destroyed after heat aging and completely destroyed after UV-heat synergism aging, while LSMB presented the sea-island structure, and the sea-island structure almost disappeared after aging. FTIR also showed that the change of carbonyl index (I C = O ), sulfoxide index (I S = O ) and butadiene double bonds index (I C = C ) of HSMB was smaller than that of LSMB after aging. The aging kinetic models of HSMB and LSMB were established by viscosity, the aging kinetic models showed that HSMB had lower aging reaction rate and larger activation energy than LSMB under the same aging condition, which meant that HSMB had better aging resistance. [ABSTRACT FROM AUTHOR]

• Self-healing capabilities of mortars under different temperatures were investigated. • Self-healing capabilities of mortars with microcapsules increased from 10 °C to 50 °C. • Crack of mortar with nano-SiO 2 /paraffin/PE wax microcapsule self-healed in 3 h at 50 °C. The ambient temperatures have significant effect on self-healing capabilities of concretes with microcapsules. Self-healing capabilities of mortars with different shell composition (paraffin, paraffin/PE wax and nano-SiO 2 /paraffin/PE wax) microcapsules containing toluene-di-isocyanate under the temperature of 10 °C, 30 °C, 50 °C and 60 °C were investigated in this paper. The compressive strength, chloride diffusion coefficient and pore size distribution of mortars containing microcapsules before and after self-healing were characterized by mechanical property test, rapid chloride migration test and nuclear magnetic resonance, respectively. The crack healing ratio of mortars during self-healing period were measured. The self-healing capabilities of mortars containing different microcapsules raised with the increase from 10 °C to 50 °C. Nevertheless, when the temperature reached 60 °C, the self-healing capability of the mortar containing paraffin microcapsules (AM1) decreased obviously, while the self-healing capabilities of the mortars containing paraffin/PE wax microcapsules (AM2) and nano-SiO 2 /paraffin/PE wax microcapsules (AM3) were almost unchanged. The self-healing capability of AM3 was superior to that of AM1 and AM2 at the same temperature. The compressive strength recovery rate, chloride diffusion coefficient recovery rate and harmful pores ratios of AM3 after pre-damaged at 50 °C for 7 d self-healing were 94.1%, 81.2% and 47.3%, respectively. When the ambient temperature reached 50 °C, the surface cracks of the mortar with three kinds of microcapsules could be completely self-healed in 5 h. However, when the temperature raised to 60 °C, the healing ratio of the crack in AM1 with a width of 0.4–0.5 mm decreased to 49.52% after 6 h self-healing. Meanwhile, the surface cracks of AM3 could be completely self-healed less than 3 h. [ABSTRACT FROM AUTHOR]