Cylindrical Vector Beam Holography without Preservation of OAM Modes.

Orbital angular momentum (OAM) multiplexed holograms have attracted a great deal of attention recently due to their physically unbounded set of orthogonal helical modes. However, preserving the OAM property in each pixel hinders fine sampling of the target image in principle and requires a fundamental filtering aperture array in the detector plane. Here, we demonstrate the concept of metasurface-based vectorial holography with cylindrical vector beams (CVBs), whose unlimited polarization orders and unique polarization distributions can be used to boost information storage capacity. Although CVBs are composed of OAM modes, the holographic images do not preserve the OAM modes in our design, enabling fine sampling of the target image in a quasi-continuous way like traditional computer-generated holograms. Moreover, the images can be directly observed by passing them through a polarizer without the need for a fundamental mode filter array. We anticipate that our method may pave the way for high-capacity holographic devices.

Helical-sampled fiber Bragg grating inscribed by a femtosecond laser in a ring core fiber.

The inscription of a helical-sampled fiber Bragg grating (HSFBG) in a ring core fiber (RCF) using a low repetition rate femtosecond laser point-by-point technique is demonstrated. The reflection spectrum exhibits several peak groups attributed to the helical-sampled structure, with the wavelength interval between different groups determined by the helical pitch. Meanwhile, the number and spacing of the peaks within each group are dictated by the RCF. An investigation into the effects of helical pitch, helical radius, and grating length of the HSFBG on the reflection spectra is conducted. Furthermore, thermal annealing experiments demonstrate that this HSFBG can survive at the temperatures up to 800°C.

Hydrophilicity and Pore Structure Enhancement in Polyurethane/Silk Protein-Bismuth Halide Oxide Composite Films for Photocatalytic Degradation of Dye.

Polyurethane/silk protein-bismuth halide oxide composite films were fabricated using a blending-wet phase transformationin situsynthesis method. The crystal structure, micromorphology, and optical properties were conducted using XRD, SEM, and UV-Vis DRS characterize techniques. The results indicated that loaded silk protein enhanced the hydrophilicity and pore structure of the polyurethane composite films. The active species BiOX were observed to grow as nanosheets with high dispersion on the internal skeleton and silk protein surface of the polyurethane-silk protein film. The photocatalytic efficiency of BiOX/PU-SF composite films was assessed through the degradation of Rhodamine B under visible light irradiation. Among the tested films, the BiOBr/PU-SF composite exhibited the highest removal rate of RhB at 98.9%, surpassing the removal rates of 93.7% for the BiOCl/PU-SF composite and 85.6% for the BiOI/PU-SF composite. Furthermore, an active species capture test indicated that superoxide radical (•O2-) and hole (h+) species played a predominant role in the photodegradation process.

Phase separation in cancer at a glance.

Eukaryotic cells are segmented into multiple compartments or organelles within the cell that regulate distinct chemical and biological processes. Membrane-less organelles are membrane-less microscopic cellular compartments that contain protein and RNA molecules that perform a wide range of functions. Liquid-liquid phase separation (LLPS) can reveal how membrane-less organelles develop via dynamic biomolecule assembly. LLPS either segregates undesirable molecules from cells or aggregates desired ones in cells. Aberrant LLPS results in the production of abnormal biomolecular condensates (BMCs), which can cause cancer. Here, we explore the intricate mechanisms behind the formation of BMCs and its biophysical properties. Additionally, we discuss recent discoveries related to biological LLPS in tumorigenesis, including aberrant signaling and transduction, stress granule formation, evading growth arrest, and genomic instability. We also discuss the therapeutic implications of LLPS in cancer. Understanding the concept and mechanism of LLPS and its role in tumorigenesis is crucial for antitumor therapeutic strategies.

Vectorial holography for independent intensity and polarization control.

Metasurface-based vectorial holography can reconstruct images with different polarization states. However, the number of polarization channels in the holographic image is relatively small in traditional methods. Here, we propose and demonstrate a metasurface vectorial hologram which carries infinite polarization channels. It can independently control the holographic pattern and polarization distribution, which can be regarded as two independent storage dimensions. We use a supercell-based metasurface to independently control the complex amplitude of the left-handed circularly polarized and right-handed circularly polarized components of the transmitted light, which then superpose in the observation plane for the vectorial pattern generation. Different from most methods, our approach does not involve complex calculations, and it is suitable for far-field design. We anticipate that it may open avenues for future applications which require arbitrary intensity and polarization control.

The bound state in the continuum in flexible terahertz metasurfaces enabled sensitive biosensing.

The combination of a flexible device and novel electromagnetic resonances offers new dimensions to manipulate electromagnetic waves and promises new device functionalities. In this study, we experimentally demonstrate a flexible metasurface that can support the bound state in the continuum (BIC) in the terahertz regime. The metasurface consists of toroidal dipole resonant units on top of the flexible polyimide substrate, which can support a terahertz Friedrich-Wintgen BIC resonance, and the resonance characteristics can be tuned by changing the parameters of the coupling unit among two resonant modes. The BIC resonances under different bending conditions are analyzed and compared, showing decent mechanical robustness. The sensing application is demonstrated by combining Fetal Bovine Serum with the flexible BIC metasurface. The measured minimum detectable concentration is 0.007 mg mL-1. Benefiting from the mechanical flexibility and BIC resonance characteristics, our approach can effectively manipulate terahertz waves and have potential applications in the realization of multifunctional and flexible photonic devices.

Compact plasmonic fiber tip for sensitive and fast humidity and human breath monitoring.

We demonstrate a plasmonic fiber tip for relative humidity (RH) detection by integrating a gold nanomembrane onto the end-face of a multimode optical fiber via a flexible and high-efficiency transfer method. Fast water condensation/evaporation is responsible for the high performance of the fiber tip in response to RH. A high sensitivity of 279 pm/%RH is obtained in the range of $ 11\% \sim 92\% {\rm RH} $11%∼92%RH. Taking advantage of the fast dynamics (response and recovery times of 156 ms and 277 ms), the plasmonic fiber tip offers an excellent detection capability to human breaths at varied frequencies and depths. The compact, easy-fabrication, and fast-dynamics plasmonic platform has versatile potential for practical applications, including environmental and healthcare monitoring, as well as biochemical sensing.

High-performance optical sensing based on electromagnetically induced transparency-like effect in Tamm plasmon multilayer structures.

We present a novel kind of optical sensor based on the electromagnetically induced transparency (EIT)-like effect in a Tamm plasmon multilayer structure, which consists of a metal film on a dielectric Bragg grating with alternatively stacked TiO2 and SiO2 layers and a defect layer. The defect layer can induce a refractive-index-sensitive ultranarrow peak in the broad Tamm plasmon reflection dip. This nonintuitive phenomenon in analogy to the EIT effect in atomic systems originates from the coupling and destructive interference between the defect and Tamm plasmon modes in the multilayer structure. Taking advantage of this EIT-like effect, we achieve an ultrahigh sensing performance with a sensitivity of 416 nm/RIU and a figure of merit (FOM) of 682 RIU-1. The numerical simulations agree well with the theoretical calculations. Additionally, the spectral line shape can be effectively tailored by changing the defect layer thickness, significantly promoting the dimensionless FOM from 0.76×104 to more than 2.4×104. Our findings will facilitate the achievement of ultrasensitive optical sensors in multilayer structures and open up perspectives for practical applications, especially in gas, biochemical, and optofluidic sensing.

Simultaneous measurement of refractive index and temperature with high sensitivity based on a multipath fiber Mach-Zehnder interferometer.

We present and experimentally demonstrate a highly sensitive sensor for simultaneously measuring the refractive index (RI) and temperature based on a multipath fiber Mach-Zehnder interferometer. The sensor is fabricated by sandwiching a segment of weak-coupling seven-core fiber (SCF) with two short multimode fibers, and then splicing it with lead-in and lead-out single-mode fibers, respectively. Six outer cores of the SCF are half-etched chemically for enhancing the interaction between light and matter. A high-quality transmission spectrum with 23 dB fringe visibility is obtained. Due to the strong interaction between the outer core modes and cladding modes with the surrounding medium, the proposed fiber structure exhibits not only an extremely high RI sensitivity of -1802.26 nm/RI unit from 1.427 to 1.442, but also a superior temperature sensitivity of 82 pm/°C from 10°C to 90°C. Moreover, RI and temperature can be discriminated simultaneously by measuring the central wavelength shifts of two transmission notches. This sensor has outstanding advantages of high sensitivity, easy fabrication, simple structure, and low cost, and may find applications in multiparameter highly sensitive sensing.

Nearly perfect absorption of light in monolayer molybdenum disulfide supported by multilayer structures.

A novel multilayer photonic structure is proposed to achieve the strong enhancement of light absorption in monolayer molybdenum disulfide (MoS2). Both numerical and analytical results illustrate that the absolute absorption of light in this atomically thin layer can approach as high as 96% at the visible wavelengths due to the excitation of Tamm plasmon mode. It is also found that the operating wavelength and height of sharp absorption peak are particularly dependent on the layer thicknesses and period number of dielectric grating, MoS2 position in the spacer, and incident angle of light, which contribute to the tunability and selectivity of light-MoS2 interaction. These results would provide a new pathway for the improvement of MoS2 photoluminescence and photodetection.

Investigation of magneto-induced linear dichroism of magnetic fluid.

A fiber-optic component is fabricated with etched fiber coated by magnetic fluid (MF) for its evanescent field to be modulated by the MF. The magneto-induced linear dichroism of the MF is investigated under different temperatures with the component. The experimental results show that the MF possesses weak linear dichroism (maximum of 2.37% at 25°C) caused by its sparse magneto-induced chains. Considering the relationships between the linear dichroisms and temperature, there is a transition point of magnetic field at ∼4 mT. Up to ∼4 mT, the linear dichroisms decrease with the temperature; however, for higher magnetic field strengths, the linear dichroisms increase with the temperature. Interestingly, a small initial linear dichroism (up to 0.255% at 5°C) without magnetic field is also observed.

Nonlinear Saturable Absorption of Liquid-Exfoliated Molybdenum/Tungsten Ditelluride Nanosheets.

Molybdenum disulfide (MoS2 ) and tungsten disulfide (WS2 ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, and chemical properties. Compared with MoS2 and WS2 , molybdenum ditelluride (MoTe2 ) and tungsten ditelluride (WTe2 ) possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting for applications in the near-infrared wavelength regime. Here, few-layer MoTe2 /WTe2 nanosheets are fabricated by a liquid exfoliation method using sodium deoxycholate bile salt as surfactant, and the nonlinear optical properties of the nanosheets are investigated. The results demonstrate that MoTe2 /WTe2 nanosheets exhibit nonlinear saturable absorption property at 1.55 µm. Soliton mode-locking operations are realized separately in erbium-doped fiber lasers utilizing two types of MoTe2 /WTe2 -based saturable absorbers, one of which is prepared by depositing the nanosheets on side polished fibers, while the other is fabricated by mixing the nanosheets with polyvinyl alcohol and then evaporating them on substrates. Numerous applications may benefit from the nonlinear saturable absorption features of MoTe2 /WTe2 nanosheets, such as visible/near-infrared pulsed laser, materials processing, optical sensors, and modulators.

Strain and high-temperature discrimination using a Type II fiber Bragg grating and a miniature fiber Fabry-Perot interferometer.

A novel method for simultaneous measurement of strain and high temperature using a Type II fiber Bragg grating (FBG) and a miniature fiber Fabry-Perot interferometer (MFFPI) is proposed. The MFFPI is produced by fusion splicing a short section of quartz capillary tube with two single-mode fibers, and then it is exposed by a focused femtosecond laser and a phase mask to inscribe a Type II FBG nearby. The reflection spectrum of this sensor is the superposition of the reflection spectrum of the FBG and the interference fringe of the MFFPI. This sensor shows perfect high-temperature and strain responses. Because of the different responses to the uniform variations of strain and temperature, by measuring the reflection peak of FBG and one of the interference dips of the MFFPI, strain and temperature can be simultaneously determined. The resolutions of this particular sensor in measuring strain and temperature are estimated to be ±8.4 µÏµ and ±3.3°C, respectively, in the range from 0 to 1122 µÏµ and from 23°C to 600°C.

Ultralong time response of magnetic fluid based on fiber-optic evanescent field.

The ultralong time (a few hours) response properties of magnetic fluid using etched optical fiber are visualized and investigated experimentally. The operating structure is made by injecting magnetic fluid into a capillary tube that contains etched single-mode fiber. An interesting extreme asymmetry is observed, in which the transmitted light intensity after the etched optical fiber cannot reach the final steady value when the external magnetic field is turned on (referred to as the falling process), while it can reach the stable state quickly once the magnetic field is turned off (referred to as the rising process). The relationship between the response times/loss rates of the transmitted light and the strength of the applied magnetic field is obtained. The physical mechanisms of two different processes are discussed qualitatively.

Optical heterodyne micro-vibration measurement based on all-fiber acousto-optic frequency shifter.

An all-fiber optical heterodyne detection configuration was proposed based on an all-fiber acousto-optic structure, which acted as both frequency shifter and coupler at the same time. The vibration waveform within a frequency range between 1 Hz to 200 kHz of a piezoelectric mirror was measured using this optical heterodyne detection system. The minimal measurable vibration amplitude and resolution are around 6 pm and 1 pm in the region of tens to hundreds of kilohertz, respectively. The configuration has advantages of compact size, high accuracy and non-contact measurement. Moreover, it is of a dynamically adjustable signal-to-noise ratio to adapt different surface with different reflections in the measurement, which will improve the usage efficiency of the light power.

Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG.

To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the "HYSY-981" ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results.

Effect of oblique force source induced by laser ablation on ultrasonic generation.

The effect of asymmetry caused by oblique line-shaped laser ablation on the generation of ultrasonic waves in metal, especially the effect of transverse component of the ablation force source on the ultrasonic waves is analyzed. Due to the oblique force source, the displacements of shear wave increase obviously by the enhanced shear force, the energy concentration area of longitudinal wave deflects to the small range centered on the incident direction while that of shear wave is approximately perpendicular to incident direction. In addition, surface wave enhances in the direction of transverse power flow. Furthermore, some ultrasonic characteristics under vortex laser ablation condition are inferred.

Ginsenoside Rg1 Alleviates Sepsis-Induced Acute Lung Injury by Reducing FBXO3 Stability in an m6A-Dependent Manner to Activate PGC-1α/Nrf2 Signaling Pathway.

BACKGROUND: Sepsis-induced acute lung injury (ALI) is one of the serious life-threatening complications of sepsis and is pathologically associated with mitochondrial dysfunction. Ginsenoside Rg1 has good therapeutic effects on ALI. Herein, the pharmacological effects of Rg1 in sepsis-induced ALI were investigated. METHODS: Sepsis-induced ALI models were established by CLP operation and LPS treatment. HE staining was adopted to analyze lung pathological changes. The expression and secretion of cytokines were measured by RT-qPCR and ELISA. Cell viability and apoptosis were assessed by MTT assay, flow cytometry and TUNEL staining. ROS level and mitochondrial membrane potential (MMP) were analyzed using DHE probe and JC-1 staining, respectively. FBXO3 m6A level was assessed using MeRIP assay. The interactions between FBXO3, YTHDF1, and PGC-1α were analyzed by Co-IP or RIP. RESULTS: Rg1 administration ameliorated LPS-induced epithelial cell inflammation, apoptosis, and mitochondrial dysfunction in a dose-dependent manner. Mechanically, Rg1 reduced PGC-1α ubiquitination modification level by inhibiting FBXO3 expression m6A-YTHDF1 dependently. As expected, Rg1's mitigative effect on LPS-induced inflammation, apoptosis and mitochondrial dysfunction in lung epithelial cells was abolished by FBXO3 overexpression. Moreover, FBXO3 upregulation eliminated the restoring effect of Rg1 on CLP-induced lung injury in rats. CONCLUSION: Rg1 activated PGC-1α/Nrf2 signaling pathway by reducing FBXO3 stability in an m6A-YTHDF1-dependent manner to improve mitochondrial function in lung epithelial cells during sepsis-induced ALI progression.

EFFECT OF STRATIFIED DOSE OF NOREPINEPHRINE ON CELLULAR IMMUNE RESPONSE IN PATIENTS WITH SEPTIC SHOCK AND THE CONSTRUCTION OF A PROGNOSTIC RISK MODEL.

ABSTRACT: Objective: To explore the effect of a stratified dose of norepinephrine (NE) on cellular immune response in patients with septic shock, and to construct a prognostic model of septic shock. Methods: A total of 160 patients with septic shock (B group) and 58 patients with sepsis (A group) were given standard cluster therapy. Patients with septic shock were divided into four groups (B1-B4 groups: 0.01-0.2, 0.2-0.5, 0.5-1.0, and >1 µg/kg/min) according to the quartile method of the early (72 h) time-weighted average dose of NE and clinical application. The cellular immune indexes at 24 h (T0) and 4-7 days (T1) after admission were collected. The difference method was used to explore the effect of NE stratified dose on cellular immune effect in patients with septic shock. A multivariate COX proportional risk regression model was used to analyze the independent prognostic risk factors, and a prognostic risk model was constructed. Results: The differences of ΔIL-1ß, ΔIL-6, ΔIL-10, absolute value difference of T lymphocyte (ΔCD3+/CD45+#) and Th helper T cell (ΔCD3+ CD4+/CD45+#), CD64 infection index difference, ΔmHLA-DR, regulatory T lymphocyte ratio difference (ΔTregs%) between group A, B1, B2, B3, and B4 were statistically significant ( P < 0.05). There was a nonlinear relation between the stratified dose of NE and ΔIL-6, ΔIL-10, ΔCD3+/CD45+#, ΔmHLA-DR%. The threshold periods of NE-induced proinflammatory and anti-inflammatory immune changes were 0.3-0.5 µg/kg/min. Multivariate COX model regression analysis showed that age, nutritional patterns, weighted average dose of norepinephrine, IL-6, absolute value of T lymphocytes, and mHLA-DR were independent risk factors affecting the prognosis of patients with septic shock ( P < 0.05). The prognostic risk model was constructed (AUC value = 0.813, 95% CI: 0.752-0.901). Conclusion: NE has a certain inhibitory effect on cellular immune function in patients with septic shock. A prognostic risk model was constructed with stronger prediction efficiency for the prognosis of patients with septic shock.

Finite element modeling of bulk ultrasonic waves generated by ring-shaped laser illumination in a diamond anvil cell.

Thermoelastic finite element models are established to study the bulk ultrasonic waves of an aluminum film generated by ring-shaped laser illumination in a diamond anvil cell. By analyzing the amplitudes of bulk ultrasonic waves arrived at the rear surface of film in detail, it shows that there exists strong enhancement effects on the central axis of the ring due to the constructive interference among the waves created by different parts of the ring source. The displacement distributions along the central axis indicate that the focal depth of shear wave is mainly determined by its directivity induced by a point-like laser source in a DAC system while it is more complicated to determine the focal depth of longitudinal wave. In particular, through changing the ring radius, we quantitatively demonstrate that the signal amplitudes generated by a ring source are far greater than those generated by a point-like source.