Linear dichroism transition and polarization-sensitive photodetector of quasi-one-dimensional palladium bromide

Perpendicular optical reversal of the linear dichroism transition has promising applications in polarization-sensitive optoelectronic devices. We perform a systematical study on the in-plane optical anisotropy of quasi-one-dimensional PdBr_(2) by using combined measurements of the angle-resolved polarized Raman spectroscopy(ARPRS) and anisotropic optical absorption spectrum. The analyses of ARPRS data validate the anisotropic Raman properties of the PdBr_(2) flake.And anisotropic optical absorption spectrum of PdBr_(2) nanoflake demonstrates distinct optical linear dichroism reversal. Photodetector constructed by PdBr_(2) nanowire exhibits high responsivity of 747 A·W^(-1) and specific detectivity of 5.8×10^(12) Jones. And the photodetector demonstrates prominent polarization-sensitive photoresponsivity under 405-nm light irradiation with large photocurrent anisotropy ratio of 1.56, which is superior to those of most of previously reported quasi-one-dimensional counterparts. Our study offers fundamental insights into the strong optical anisotropy exhibited by PdBr_(2), establishing it as a promising candidate for miniaturization and integration trends of polarization-related applications.

Simultaneous fluorescence and Compton scattering computed tomography based on linear polarization X-ray

Purpose To propose a method for simultaneous fluorescence and Compton scattering computed tomography by using linearly polarized X-rays.Methods Monte Carlo simulations were adopted to demonstrate the feasibility of the proposed method.In the simulations,the phantom is a polytetrafluoroethylene cylinder inside which are cylindrical columns containing aluminum,water,and gold(Au)-loaded water solutions with Au concentrations ranging between 0.5 and 4.0 wt%,and a parallel-hole collimator imaging geometry was adopted.The light source was modeled based on a Thomson scattering X-ray source.The phantom images for both imaging modalities were reconstructed using a maximumlikelihood expectation maximization algorithm.Results Both the X-ray fluorescence computed tomography(XFCT)and Compton scattering computed tomography(CSCT)images of the phantom were accurately reconstructed.A similar attenuation contrast problem for the different cylindrical columns in the phantom can be resolved in the XFCT and CSCT images.The interplay between XFCT and CSCT was analyzed,and the contrast-to-noise ratio(CNR)of the reconstruction was improved by correcting for the mutual influence between the two imaging modalities.Compared with K-edge subtraction imaging,XFCT exhibits a CNR advantage for the phantom.Conclusion Simultaneous XFCT and CSCT can be realized by using linearly polarized X-rays.The synergy between the two imaging modalities would have an important application in cancer radiation therapy.

A Multifunctional Chiral Metasurface with Asymmetric Transmission and Linear-Polarization Conversion

In this paper,a multifunctional chiral metasurface is presented to achieve asymmetric transmission(AT)and linear-polarization conversion(LPC).The designed metasurface consists of a cross swords-like shape and two holes in the lower side of the unit cell.In the frequency band from 8.3 GHz to 10.4 GHz,AT is realized with more than 90%efficiency and the same chiral metasurface transforms linear polarized wave into its orthogonal counterpart with high efficiency.For LPC,the polarization conversion ratio(PCR)is greater than 95%.The proposed metasurface is stable against the incident angles of striking electromagnetic(EM)waves up to 60°for both operations of AT and LPC.

Calculus bovis inhibits M2 tumor-associated macrophage polarization via Wnt/β-catenin pathway modulation to suppress liver cancer

BACKGROUND Calculus bovis(CB),used in traditional Chinese medicine,exhibits anti-tumor effects in various cancer models.It also constitutes an integral component of a compound formulation known as Pien Tze Huang,which is indicated for the treatment of liver cancer.However,its impact on the liver cancer tumor microenvironment,particularly on tumor-associated macrophages(TAMs),is not well understood.AIM To elucidate the anti-liver cancer effect of CB by inhibiting M2-TAM polarization via Wnt/β-catenin pathway modulation.METHODS This study identified the active components of CB using UPLC-Q-TOF-MS,evaluated its anti-neoplastic effects in a nude mouse model,and elucidated the underlying mechanisms via network pharmacology,transcriptomics,and molecular docking.In vitro assays were used to investigate the effects of CB-containing serum on HepG2 cells and M2-TAMs,and Wnt pathway modulation was validated by real-time reverse transcriptase-polymerase chain reaction and Western blot analysis.RESULTS This study identified 22 active components in CB,11 of which were detected in the bloodstream.Preclinical investigations have demonstrated the ability of CB to effectively inhibit liver tumor growth.An integrated approach employing network pharmacology,transcriptomics,and molecular docking implicated the Wnt signaling pathway as a target of the antineoplastic activity of CB by suppressing M2-TAM polarization.In vitro and in vivo experiments further confirmed that CB significantly hinders M2-TAM polarization and suppresses Wnt/β-catenin pathway activation.The inhibitory effect of CB on M2-TAMs was reversed when treated with the Wnt agonist SKL2001,confirming its pathway specificity.CONCLUSION This study demonstrated that CB mediates inhibition of M2-TAM polarization through the Wnt/β-catenin pathway,contributing to the suppression of liver cancer growth.

Myricetin induces M2 macrophage polarization to alleviate renal tubulointerstitial fibrosis in diabetic nephropathy via PI3K/Akt pathway

BACKGROUND Development of end-stage renal disease is predominantly attributed to diabetic nephropathy(DN).Previous studies have indicated that myricetin possesses the potential to mitigate the pathological alterations observed in renal tissue.Never-theless,the precise molecular mechanism through which myricetin influences the progression of DN remains uncertain.AIM To investigate the effects of myricetin on DN and explore its potential therapeutic mechanism.METHODS Db/db mice were administered myricetin intragastrically on a daily basis at doses of 50 mg/kg or 100 mg/kg for a duration of 12 wk.Subsequently,blood and urine indexes were assessed,along with examination of renal tissue pathology.Kidney morphology and fibrosis were evaluated using various staining techniques including hematoxylin and eosin,periodic acid–Schiff,Masson’s trichrome,and Sirius-red.Additionally,high-glucose culturing was conducted on the RAW 264.7 cell line,treated with 25 mM myricetin or co-administered with the PI3K/Akt inhibitor LY294002 for a period of 24 h.In both in vivo and in vitro settings,quantification of inflammation factor levels was conducted using western blotting,real-time qPCR and ELISA.RESULTS In db/db mice,administration of myricetin led to a mitigating effect on DN-induced renal dysfunction and fibrosis.Notably,we observed a significant reduction in expressions of the kidney injury markers kidney injury molecule-1 and neutrophil gelatinase associated lipocalin,along with a decrease in expressions of inflammatory cytokine-related factors.Furthermore,myricetin treatment effectively inhibited the up-regulation of tumor necrosis factor-alpha,interleukin-6,and interluekin-1βinduced by high glucose in RAW 264.7 cells.Additionally,myricetin modulated the M1-type polarization of the RAW 264.7 cells.Molecular docking and bioinformatic analyses revealed Akt as the target of myricetin.The protective effect of myricetin was nullified upon blocking the polarization of RAW 264.7 via inhibition of PI3K/Akt activation using LY294002.CONCLUSION This study demonstrated that myricetin effectively mitigates kidney injury in DN mice through the regulation of macrophage polarization via the PI3K/Akt signaling pathway.

Atherosis-associated lnc_000048 activates PKR to enhance STAT1-mediated polarization of THP-1 macrophages to M1 phenotype

Our previous study has demonstrated that lnc_000048 is upregulated in large-artery atherosclerotic stroke and promotes atherosclerosis in ApoE^(-/-)mice.However,little is known about the role of lnc_000048 in classically activated macrophage(M1)polarization.In this study,we established THP-1-derived testing state macrophages(M0),M1 macrophages,and alternately activated macrophages(M2).Real-time fluorescence quantitative PCR was used to verify the expression of marker genes and the expression of lnc_000048 in macrophages.Flow cytometry was used to detect phenotypic proteins(CD11b,CD38,CD80).We generated cell lines with lentivirus-mediated upregulation or downregulation of lnc_000048.Flow cytometry,western blot,and real-time fluorescence quantitative PCR results showed that down-regulation of lnc_000048 reduced M1 macrophage polarization and the inflammation response,while over-expression of lnc_000048 led to the opposite effect.Western blot results indicated that lnc_000048 enhanced the activation of the STAT1 pathway and mediated the M1 macrophage polarization.Moreover,catRAPID prediction,RNA-pull down,and mass spectrometry were used to identify and screen the protein kinase RNA-activated(PKR),then catRAPID and RPIseq were used to predict the binding ability of lnc_000048 to PKR.Immunofluorescence(IF)-RNA fluorescence in situ hybridization(FISH)double labeling was performed to verify the subcellular colocalization of lnc_000048 and PKR in the cytoplasm of M1 macrophage.We speculate that lnc_000048 may form stem-loop structure-specific binding and activate PKR by inducing its phosphorylation,leading to activation of STAT1 phosphorylation and thereby enhancing STAT1 pathway-mediated polarization of THP-1 macrophages to M1 and inflammatory factor expression.Taken together,these results reveal that the lnc_000048/PKR/STAT1 axis plays a crucial role in the polarization of M1 macrophages and may be a novel therapeutic target for atherosclerosis alleviation in stroke.

Generation of structured light beams with polarization variation along arbitrary spatial trajectories using tri-layer metasurfaces

Conventionally,the spatially structured light beams produced by metasurfaces primarily highlight the polarization modulation of the beams propagating along the optical axis or the beams'spatial transmission trajectory.In particular,along the optical axis,the polarization state is either constant or varies continuously in each output plane.Here,we develop innovative spatially structured light beams with continually changing polarization along any arbitrary spatial transmission trajectories.With tri-layer metallic metasurfaces,the geometric characteristics of each layer structure can be adjusted to modulate the phase and polarization state of the incident terahertz(THz)wave.The beam will converge to the predefined trajectory along several paths to generate a Bessel-like beam with longitudinal polarization changes.We demonstrate the versatility of the approach by designing two THz-band structured light beams with varying polarization states along the spatial helical transmission trajectory.Continuous linear polarization changes and linear polarization to right circular polarization(RCP)and back to linear polarization changes are realized respectively.The experimental results are basically consistent with the simulated results.Our proposal for arbitrary trajectory structured light beams with longitudinally varying polarization offers a practical method for continuously regulating the characteristics of spatial structured light beams with non-axial transmission.This technique has potential uses in optical encryption,particle manipulation,and biomedical imaging.

Cell polarization in ischemic stroke: molecular mechanisms and advances

Ischemic stroke is a cerebrovascular disease associated with high mortality and disability rates. Since the inflammation and immune response play a central role in driving ischemic damage, it becomes essential to modulate excessive inflammatory reactions to promote cell survival and facilitate tissue repair around the injury site. Various cell types are involved in the inflammatory response, including microglia, astrocytes, and neutrophils, each exhibiting distinct phenotypic profiles upon stimulation. They display either proinflammatory or anti-inflammatory states, a phenomenon known as ‘cell polarization.’ There are two cell polarization therapy strategies. The first involves inducing cells into a neuroprotective phenotype in vitro, then reintroducing them autologously. The second approach utilizes small molecular substances to directly affect cells in vivo. In this review, we elucidate the polarization dynamics of the three reactive cell populations(microglia, astrocytes, and neutrophils) in the context of ischemic stroke, and provide a comprehensive summary of the molecular mechanisms involved in their phenotypic switching. By unraveling the complexity of cell polarization, we hope to offer insights for future research on neuroinflammation and novel therapeutic strategies for ischemic stroke.

Analysis and inversion of target polarization characteristics based on pBRDF

Imaging detection is an important means to obtain target information.The traditional imaging detection technology mainly collects the intensity information and spectral information of the target to realize the classification of the target.In practical applications,due to the mixed scenario,it is difficult to meet the needs of target recognition.Compared with intensity detection,the method of polarization detection can effectively enhance the accuracy of ground object target recognition(such as the camouflage target).In this paper,the reflection mechanism of the target surface is studied from the microscopic point of view,and the polarization characteristic model is established to express the relationship between the polarization state of the reflected signal and the target surface parameters.The polarization characteristic test experiment is carried out,and the target surface parameters are retrieved using the experimental data.The results show that the degree of polarization(DOP)is closely related to the detection zenith angle and azimuth angle.The(DOP)of the target is the smallest in the direction of light source incidence and the largest in the direction of specular reflection.Different materials have different polarization characteristics.By comparing their DOP,target classification can be achieved.

High-Power Raman Soliton Generation at 1.7 μm in All-Fiber Polarization-Maintaining Erbium-Doped Amplifier

An all-fiber polarization maintaining high-power laser system operating at 1.7 μm based on the Ramaninduced soliton self-frequency shifting effect is demonstrated. The entirely fiberized system is built by erbiumdoped oscillator and two-stage amplifiers with polarization maintaining commercial silica fibers and devices, which can provide robust and stable soliton generation. High-power soliton laser with the average power of 0.28 W,the repetition rate of 42.7 MHz, and pulse duration of 515 fs is generated directly from the main amplifier.Our experiment provides a feasible method for high-power all-fiber polarization maintaining femtosecond laser generation working at 1.7 μm.

Tunneling Barrier Thickness Dependence of Spin Polarization of Ferromagnet in Magnetic Tunnel Junctions

For designing low-impedance magnetic tunnel junctions(MTJs),it has been found that tunneling magnetoresistance strongly correlates with the insulating barrier thickness,imposing a fundamental problem about the relationship between spin polarization of ferromagnet and the insulating barrier thickness in MTJs.Here,we investigate the influence of alumina barrier thickness on tunneling spin polarization(TSP)through a combination of theoretical calculations and experimental verification.Our simulating results reveal a significant impact of barrier thickness on TSP,exhibiting an oscillating decay of TSP with the barrier layer thinning.Experimental verification is realized on FeNi/AlO_(x)/Al superconducting tunnel junctions to directly probe the spin polarization of FeNi ferromagnet using Zeeman-split tunneling spectroscopy technique.These findings provide valuable insights for designs of high-performance spintronic devices,particularly in applications such as magnetic random access memories,where precise control over the insulating barrier layer is crucial.

Fully polarized Compton scattering in plane waves and its polarization transfer

Fully polarized Compton scattering from a beam of spin-polarized electrons is investigated in plane-wave backgrounds in a broad intensity region from the perturbative to the nonperturbative regimes.In the perturbative regime,polarized linear Compton scattering is considered for investigating polarization transfer from a single laser photon to a scattered photon,and in the high-intensity region,the polarized locally monochromatic approximation and locally constant field approximation are established and are employed to study polarization transfer from an incoming electron to a scattered photon.The numerical results suggest an appreciable improvement of about 10%in the scattering probability in the intermediate-intensity region if the electron’s longitudinal spin is parallel to the laser rotation.The longitudinal spin of the incoming electron can be transferred to the scattered photon with an efficiency that increases with laser intensity and collisional energy.For collision between an optical laser with frequency1 eV and a 10 GeV electron,this polarization transfer efficiency can increase from about 20%in the perturbative regime to about 50%in the nonperturbative regime for scattered photons with relatively high energy.

Ultra-broadband and wide-angle reflective terahertz polarization conversion metasurface based on topological optimization

Terahertz polarization conversion devices have significant potential applications in various fields such as terahertzimaging and spectroscopy.In this paper,we utilize genetic algorithms to topologically optimize the metasurface unit cellsand design a reflective linear polarization conversion metasurface with ultra-broadband and wide-angle characteristics.By partitioning the metallic pattern layer into quadrants,the encoding length is effectively reduced,resulting in a shorteroptimization time.The research results indicate that the converter possesses a polarization conversion efficiency ratio higherthan 90%and a relative bandwidth ratio of 125%in a range of 0.231-0.995 THz.Meanwhile,it can maintain excellentpolarization conversion properties when the incident angle of terahertz waves is less than 45°and the polarization angle isless than 15°,demonstrating excellent practicality.New insights are provided for the design of terahertz wide-angle ultrawidebandpolarization conversion devices,and the proposed metasurfce has potential applications in terahertz polarizationimaging,spectroscopy and communication fields.

Polydatin ameliorates hepatic ischemia-reperfusion injury by modulating macrophage polarization

Background:Polydatin,a glucoside of resveratrol,has shown protective effects against various diseases.However,little is known about its effect on hepatic ischemia-reperfusion(I/R)injury.This study aimed to elucidate whether polydatin protects liver against I/R-induced injury and to explore the underlying mechanism.Methods:After gavage feeding polydatin once daily for a week,mice underwent a partial hepatic I/R procedure.Serum alanine aminotransferase(ALT)/aspartate aminotransferase(AST),hematoxylin-eosin(H&E)and TdT-mediated dUTP nick-end labeling(TUNEL)staining were used to evaluate liver injury.The severity related to the inflammatory response and reactive oxygen species(ROS)production was also investigated.Furthermore,immunofluorescence and Western blotting were used to detect macrophage polarization and the NF-κB signaling pathway in macrophages.Results:Compared with the I/R group,polydatin pretreatment significantly attenuated I/R-induced liver damage and apoptosis.The oxidative stress marker(dihydroethidium fluorescence,malondialdehyde,superoxide dismutase and glutathione peroxidase)and I/R related inflammatory cytokines(interleukin1β,interleukin-10 and tumor necrosis factor-α)were significantly suppressed after polydatin treatment.In addition,the result of immunofluorescence indicated that polydatin reduced the polarization of macrophages toward M1 macrophages both in vivo and in vitro.Western blotting showed that polydatin inhibited the pro-inflammatory function of RAW264.7 via down-regulating the NF-κB signaling pathway.Conclusions:Polydatin protects the liver from I/R injury by remodeling macrophage polarization via NFκB signaling.

Effect of electron-electron interaction on polarization process of exciton and biexciton in conjugated polymer

By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.

Polarization control of above-threshold ionization spectrum in elliptically polarized two-color laser fields

We study the above-threshold ionization(ATI)process of atoms exposed to fundamental and high-frequency lasers with arbitrary ellipticity by applying the frequency-domain theory.It is found that the angular-resolved ATI spectrum is sensitive to ellipticities of two lasers and emitted angles of the photoelectron.Particularly for the photon energy of the highfrequency laser more than atomic ionization potential,the width of plateau tends to a constant with increasing ellipticity of fundamental field,the dip structure disappears with increasing ellipticity of the high-frequency field.With the help of the quantum channel analysis,it is shown that the angular distribution depends mainly on the ellipticity of high-frequency field in the case that its frequency is high.Moreover,one can see that the maximal and minimal energies in quantum numerical results are in good agreement with the classical prediction.Our investigation may provide theoretical support for experimental research on polarization control of ionization in elliptically polarized two-color laser fields.

Linearly Polarization-Sensitive Perovskite Photodetectors

Polarization means symmetry loss for light vibration along light propagation direction,which is a particular physical property of light.The polarization state is indecipherable for most polarization-insensitive detectors.Polarization can carry and differentiate light information,and can be used in polarized light detection,polarization imaging and encryption communication[1].Photodetectors are the core component of some photoelectric devices[2]used in biomedical sensing,remote sensing,military field,etc.

Intrinsic polarization conversion and avoided-mode crossing in X-cut lithium niobate microrings

Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides,which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes(TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.

A 1-bit electronically reconfigurable beam steerable metasurface reflectarray with multiple polarization manipulations

A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180°out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y-or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 d Bi and 17.26 d Bi within the scan range of about ±50°. With the right-handed circular polarization(RHCP) excitation, the left-handed circular polarization(LHCP) radiation with the peak gain of 16.98 d Bic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.

The First Ground-based White Light Lunar Polarization Imaging:A New Kind of FeO Observation on the Near Side of the Moon

Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.