Cubic Na0.5Bi0.5TiO3 nanoperovskite significantly expands the application of sensitive immunosensor for the detection of carcinoembryonic antigen.

Nanosized sodium bismuth perovskite titanate (NBT) was synthesized and first used as the electrochemical immune sensing platform for the sensitive detection of carcinoembryonic antigen (CEA). Gold nanoparticles (Au NPs) grew on the surface of NBT through forming Au-N bond to obtain Au@NBT, and a label-free electrochemical immunosensor was proposed using Au@NBT as an immunosensing recognizer towards CEA. The well-ordered crystal structure of NBT was not changed at all after the modification of Au NPs outside, but significantly improved the conductivity, catalytic activity, and biocompatibility of the Au@NBT-modified electrode. The unique cubic crystal nanostructure of NBT offered a large active area for both Au NP modification and the subsequent immobilization of biomolecules over the electrode surface, triggering the effective generation of promising properties of the proposed Au@NBT-based electrochemical immunosensor. As expected, favorable detection performances were achieved using this immunosensor towards CEA detection, where a good linear relationship between the current response and CEA concentration was obtained in the concentration range 10 fg mL-1 to 100 ng mL-1 with a low detection limit (LOD) of 13.17 fg mL-1. Also, the significantly enhanced selectivity, and stability guaranteed the promising electrochemical properties of this immunosensor. Furthermore, the analysis of real serum samples verified the high feasibility of this new method in clinical CEA detection. This work opens a new window for the application of nanoperovskite in the early detection of CEA.

All-optical self-manipulation of light flow in on-chip topological waveguides based on synthetic dimension.

Topological photonic crystals provide a new platform for designing nanophotonic devices with robustness. Especially, all-optical devices, which use the light controlling light, based on nonlinear topological photonic crystals, have not been reported yet. In this article, we numerically investigate the robust self-manipulation of light flow in silicon topological photonic crystal waveguides based on the Kerr nonlinearity of silicon and topological edge states of photonic crystal waveguides. By adjusting the intensity of incident light at a communication wavelength of 1550 nm, the transmission path of the light flow in waveguides can be effectively controlled, and such manipulation is immune to some disturbances of nanostructures and thus shows the robustness. The results indicate that nonlinear topological photonic crystals have potential applications in on-chip integrated all-optical photonic devices.

Ti3C2@Bi2O3 nanoaccordion for electrochemical determination of miRNA-21.

Based on a dual signal amplification strategy of novel accordion-like Bi2O3-decorated Ti3C2 (Ti3C2@Bi2O3) nanocomposites and hybridization chain reaction (HCR), an ultra-sensitive electrochemical biosensor was constructed for miRNA-21 detection. By etching Ti3AlC2 with HF, Ti3C2 with an accordion-like structure was first obtained and subsequently covered by Bi2O3 nanoparticles (NPs), forming Ti3C2@Bi2O3. A layer of Au NPs was electrodeposited on the glassy carbon electrode coated with Ti3C2@Bi2O3, which not only significantly improved the electron transport capacity of the electrode but also greatly increased its surface active area. Upon the immobilization of the thiolated capture probe (SH-CP) on the electrode, the target miRNA-21 specifically hybridized with SH-CP and thus opened its hairpin structure, triggering HCR to form a long double strand with the primers H1 and H2. A large number of the electrochemical indicator molecules were thus embedded inside the long double strands to produce the desirable electrochemical signal at a potential of - 0.19 V (vs. Ag/AgCl). Such dual signal amplification strategy successfully endowed the biosensor with ultra-high sensitivity for miRNA-21 detection in a wide linear range from 1 fM to 100 pM with a detection limit as low as 0.16 fM. The excellent detection of miRNA-21 in human blood plasma displayed a broad prospect in clinical diagnosis. An ultra-sensitive electrochemical biosensor was successfully constructed for miRNA-21 detection in human blood plasma based on the dual signal amplification strategy of novel accordion-like Bi2O3 decorated Ti3C2 (Ti3C2@Bi2O3) nanocomposites and hybridization chain reaction.

Pt Nanodot Inlaid Mesoporous NaBiOF Nanoblackberry for Remarkable Signal Amplification Toward Biomarker Detection.

A new ultrasensitive sandwich-type electrochemical immunosensor has been successfully constructed to quantitatively detect carcinoembryonic antigen (CEA) using blackberry-like mesoporous bismuth-based nanospheres NaBiOF (NBOF NSs) inlaid with Pt nanodots (NDs) (BiPt NSs) as the antibody capture and signal-amplifying probe. The growth of Pt NDs inside the holes of NBOF NSs formed the nanozyme inlay outside NBOF NSs, greatly increasing the specific surface area and exposure of the catalytic active sites by minimizing the particle size of the Pt to nanodot scale. Such a blackberry-shaped heterojunction structure of BiPt NSs was well-suited to antibody capture and improved the catalytic performance of BiPt NSs in reducing H2O2, amplifying the signal, and yielding highly sensitive detection of CEA. The use of Au nanoparticle-modified multi-walled carbon nanotubes (Au@MWCNTs) as the electrode substrates significantly enhanced the electron transfer behavior over the electrode surface, further increasing the conductivity and sensitivity of the immunosensor. Remarkably, good compatibility with human body fluid was achieved using the newly developed BiPt-based immunosensor resulting from the favorable biocompatibility and stability of both BiPt NSs and Au@MWCNTs. Benefiting from the double signal amplification strategy and the high biocompatibility, the immunosensor responded linearly to CEA in a wide range from 50 fg/mL to 100 ng/ml with an extremely low detection limit of 3.52 fg/mL (S/N = 3). The excellent detection properties of this new immunosensor were evidenced by the satisfactory selectivity, reproducibility, and stability obtained, as well as the reliable and precise determination  of CEA in actual human blood samples. This work provides a new strategy for the early clinical diagnosis of cancer. Novel blackberry-like mesoporous NaBiOF nanospheres with Pt nanodot inlay were successfully usedto construct a sandwich-type electrochemical immunosensor for the ultra-sensitive detection ofcarcinoembryonic antigen in human blood plasma based on a remarkable signal amplification strategy.

Free-space remote detection of a spinning object using the combined vortex beam.

The rotational Doppler effect (RDE) associated with orbital angular momentum (OAM) has been used for remote sensing of a spinning object. However, one of the challenges of long-range detection stems from the low echo signal power. In this paper, we propose a new detection scheme that uses the combined vortex beam (CVB) generated by coherent beam combining (CBC) technology as the probe beam to enhance the echo signal power. Furthermore, we establish a rotational speed remote sensing model based on RDE, the emitted power and emission diameter of the probe beam are investigated in detail. The results show that, compared with the superposition vortex beam (SVB) generated by a single laser beam, the CVB detection scheme can significantly enhance the echo signal intensity and detection distance. The measuring range and accuracy of rotational speed are also studied in detail. And finally, we present the first experimental demonstration of the RDE arising directly from the interaction of the CVB with a rotating rough surface. The scheme proposed in our paper offers a good reference for practical application of the remote detection based on RDE.

Enhanced fiber-coupling efficiency via high-order partially coherent flat-topped beams for free-space optical communications.

The fiber-coupling efficiency of signal beams is crucial in free space optical (FSO) communications. Herein, we derived an analytical expression for the fiber-coupling efficiency of partially coherent flat-topped beams propagating through atmospheric turbulence based on the cross-spectral density function. Our numerical calculation results showed that the fiber-coupling efficiency of partially coherent flat-topped beams in a turbulent atmosphere could be enhanced by increasing the beam order. Under the same conditions, the fiber-coupling efficiency of the high-order partially coherent flat-topped beams was larger than those connected to the Gaussian and Gaussian Schell-model (GSM) beams. Our results will improve the quality of partially coherent beams used in FSO communications.

Exciton-induced mid-infrared optical nonlinearity of wide bandgap hexagon boron nitride.

In this Letter, an exciton absorption assumption is made to explain the mid-infrared saturable absorption performance of the 2D h-BN nanosheet. The exciton binding energy of ∼0.4 eV corresponds to the light wavelength around 3 µm, matching well with the experimental results. Experimentally, the h-BN saturable absorber (SA) shows a modulation depth of 5.3% in the wavelength region of 3 µm. By employing the h-BN SA in an Er:Lu2O3 laser, laser pulses with a pulse duration of 252 ns are realized at a repetition rate of 169 kHz, corresponding to a pulse energy of 3.55 µJ and peak power of 14 W. The exciton absorption assumption will help obtain a better understanding of the nonlinear optical dynamics in 2D materials from a new perspective.

Sensitive detection of radio-frequency field phase with interacting dark states in Rydberg atoms.

An efficient scheme of phase measurement of a radio-frequency (RF) field is proposed by interacting dark states. Under the condition of electromagnetically induced transparency (EIT), the four-level Rydberg atom exhibits two windows. Compared with the transmission spectrum on resonance, the linewidths of absorption peaks off resonance are very narrow due to the interaction of double dark states. It is interesting to find that the distance of absorption peaks shifts approximately linearly with the phase of an RF field, which can be used to measure the RF field phase. Simulation results show that the linewidth of an absorption peak can be narrowed by more than one order of magnitude, and a narrow linewidth improves the detectable minimum phase difference by more than six times. It helps to reduce analyzation complexity and increase sensing resilience. The dependence of phase measurement on the control field and RF field is also investigated.

METTL3 promotes non-small cell lung cancer (NSCLC) cell proliferation and colony formation in a m6A-YTHDF1 dependent way.

BACKGROUND: N6-methyladenosine (m6A) is the most common RNA modification, which plays a pivotal role in tumor development and progression. In this study, we assessed the role of m6A methyltransferase METTL3 in FRAS1-involved cell proliferation and colony formation of non-small cell lung cancer (NSCLC) cell lines. METHODS: Cell viability was analyzed by Cell Counting Kit (CCK-8) and colony formation. M6A RNA immunoprecipitation (IP), Ribosomal immunoprecipitation, RNA immunoprecipitation (RIP) were performed to verify the relationship between METTL3, FRAS1 and YTHDF1. Rescue experiments to confirm the regulatory mechanism of METTL3-FRAS1 promoted NSCLC cell proliferation through CDON by cooperating YTHDF1. RESULTS: We found that FRAS1 was correlated with poor prognosis in NSCLC patients, of which the transcript undergoes m6A modification regulated by METTL3. METTL3 silence reduced cell viability of NSCLC cells HCC827 and NCI-H1975, which could be restored by FRAS1 overexpression. The m6A modification of FRAS1 could be recognized by YTHDF1. FRAS1 silence or YTHDF1 silence could rescue the elevated NSCLC cell proliferation, colony formation, and tumor growth induced by METTL3 overexpression in vitro and in vivo. CONCLUSIONS: Our study reveals that METTL3-FRAS1 plays a crucial role in NSCLC cell proliferation, colony formation, and tumor growth through the regulation of CDON by cooperating YTHDF1.

Multi-Object Positioning and Imaging Based on Single-Pixel Imaging Using Binary Patterns.

Single-pixel imaging (SPI) is a new type of imaging technology that uses a non-scanning single-pixel detector to image objects and has important application prospects and value in many fields. Most of the modulators currently used in SPI systems are digital micromirror device (DMD) modulators, which use a higher frequency for binary modulation than other alternatives. When modulating grayscale information, the modulation frequency is significantly reduced. This paper conducts research on multiple discrete objects in a scene and proposes using binary patterns to locate and image these objects. Compared with the existing methods of using gray patterns to locate and image multiple objects, the method proposed in this paper is more suitable for DMD-type SPI systems and has wider applicability and greater prospects. The principle of the proposed method is introduced, and the effectiveness of the method is experimentally verified. The experimental results show that, compared to traditional SPI methods, the number of patterns required by the proposed method is reduced by more than 85%.

Investigation on the optical nonlinearity of the layered magnesium-mediated metal organic framework (Mg-MOF-74).

The wavelength-related optical nonlinearities of few-layer Mg-MOF-74 nanosheets were investigated in the wavelength region around 1.08, 1.94, and 2.85 µm by the closed aperture Z-scan, open aperture Z-scan and I-scan method. Under the excitation of 100-µJ laser pulses, the nonlinear refractive index (n2) of -7.7 ± 2.6, -131 ± 5 and 4.9 ± 0.2 cm2/W were obtained, respectively. The wavelength-related optical nonlinearity of the Mg-MOF-74 nanosheet was also investigated. In 2.85 µm wavelength region, the Mg-MOF-74 nanosheets shows a stable saturable absorption property with a modulation depth of 8% and a saturation intensity of 170 mJ/cm2. In the 1.08 and 1.94 µm wavelength regions, we can observe that the Mg-MOF-74 transits from saturable absorption regime to reverse saturable absorption regime with the increasing incident laser intensity. Employed as a saturable absorber in a Er:Lu2O3 laser, Mg-MOF-74 nanosheet shows a thickness-related laser modulation performance. The shortest laser pulse of 284-ns was achieved under a repetition rate of 116 kHz with a 6-nm-thick Mg-MOF-74 nanosheet, which corresponds to a pulse energy of 3.2 µJ and a peak power of 11.4 W.

Optical nonlinearity and laser modulation performance of FeNi-LDH in the mid-infrared region.

In this Letter, we prepare FeNi-layered-double-hydroxide (LDH) nanoflakes and illustrate the corresponding microcosmic morphology. The optical response and laser modulation performance of the nanoflakes in the mid-infrared region were investigated for the first time, to the best of our knowledge. Employed as a saturable absorber in an ${\rm Er}{:}{\rm Lu}_2{\rm O}_3$ laser system, pulses with 256-ns duration were yielded at a repetition of 129 kHz under 7.8-W pump power, which corresponds to a pulse energy of 4.98 µJ.

Modulation of MXene Nb2CTx saturable absorber for passively Q-switched 2.85 µm Er:Lu2O3laser.

We proposed a passively stabilized Q-switched Er:Lu2O3 laser at 2845 nm, applying a MXene Nb2CTx nanosheets saturable absorber prepared by the liquid-phase exfoliation method. The surface morphology and nonlinear properties of this nanosheet were systematically characterized. Average output power of 542 mW for the Q-switched laser was obtained under 7.26 W of absorbed pump power. Meanwhile, the Q-switched pulse duration was measured to be 223.7 ns with 142.9 kHz repetition rate corresponding to a peak power of 16.96 W.

The Investigation on Ultrafast Pulse Formation in a Tm-Ho-Codoped Mode-Locking Fiber Oscillator.

We experimentally investigate the formation of various pulses from a thulium-holmium (Tm-Ho)-codoped nonlinear polarization rotation (NPR) mode-locking fiber oscillator. The ultrafast fiber oscillator can simultaneously operate in the noise-like and soliton mode-locking regimes with two different emission wavelengths located around 1947 and 2010 nm, which are believed to be induced from the laser transition of Tm3+ and Ho3+ ions respectively. When the noise-like pulse (NLP) and soliton pulse (SP) co-exist inside the laser oscillator, a maximum output power of 295 mW is achieved with a pulse repetition rate of 19.85-MHz, corresponding to a total single pulse energy of 14.86 nJ. By adjusting the wave plates, the fiber oscillator could also deliver the dual-NLPs or dual-SPs at dual wavelengths, or single NLP and single SP at one wavelength. The highest 61-order harmonic soliton pulse and 33.4-nJ-NLP are also realized respectively with proper design of the fiber cavity.

A Noisy SAR Image Fusion Method Based on NLM and GAN.

The unavoidable noise often present in synthetic aperture radar (SAR) images, such as speckle noise, negatively impacts the subsequent processing of SAR images. Further, it is not easy to find an appropriate application for SAR images, given that the human visual system is sensitive to color and SAR images are gray. As a result, a noisy SAR image fusion method based on nonlocal matching and generative adversarial networks is presented in this paper. A nonlocal matching method is applied to processing source images into similar block groups in the pre-processing step. Then, adversarial networks are employed to generate a final noise-free fused SAR image block, where the generator aims to generate a noise-free SAR image block with color information, and the discriminator tries to increase the spatial resolution of the generated image block. This step ensures that the fused image block contains high resolution and color information at the same time. Finally, a fused image can be obtained by aggregating all the image blocks. By extensive comparative experiments on the SEN1-2 datasets and source images, it can be found that the proposed method not only has better fusion results but is also robust to image noise, indicating the superiority of the proposed noisy SAR image fusion method over the state-of-the-art methods.

Triple charge-coupled device cameras combined backscatter lidar for retrieving PM2.5 from aerosol extinction coefficient.

The vertical aerosol extinction coefficient profile is the key to evaluating the aerosol radiation effect. In addition, it is also the premise of indirect inversion of PM2.5 concentration from the lidar signal. A novel lidar system combining tripe charge-coupled device (CCD) cameras and backscatter lidar is proposed to retrieve accurately the aerosol extinction coefficient. The relative humidity segmentation method is used to convert the aerosol extinction coefficient into PM2.5 concentrations. The results show that the combination of triple CCDs and backscatter lidar can obtain a wider-range extinction coefficient profile. The variation trend of fitted PM2.5 concentrations and PM2.5 concentrations measured by the in situ instrument show a high correlation. The correlation coefficient reaches 0.850.

Third-harmonic generation from gold nanowires of rough surface considering classical nonlocal effect.

We demonstrate that the nonlocal dielectric response of metal, comparing with the traditional local model, will significantly boost the third-order harmonic generation (THG) from gold nanowires of rough surface by a factor of several orders of magnitude. The enhancement is probably due to the penetrated field into the fine nanostructures on the metal surface in nonlocal model. The anisotropy THG efficiency versus the angle of incidence is also demonstrated due to the inhomogeneous surface morphology. The possible ways to verify the nonlocal effect to the THG are demonstrated. The results have a general significance in explaining the experimental observations.

Defect compensation and intervalence charge transfer state-based Pr3+-doped niobate antithermal quenching phosphors.

Herein, a scheme of Sr2+/Ca2+ ion substitution was employed to simultaneously regulate the defect and intervalence charge transfer (IVCT) state of Sr2-xCaxNb2O7:Pr3+ phosphors, resulting in a dual-modulation strategy for enhancing phosphor thermal stability.

Construction of thermally stable Tb3+-activated green-emitting phosphors: dual driving strategy of doping concentration and excitation wavelength.

The realization of thermally stable Tb3+-doped green emission at high temperatures in solid-state lighting is still a crucial challenge. Nevertheless, the study on modulating the thermally stable luminescence at high temperatures is seldom reported. The position of the intervalence charge transfer (IVCT) energy level is used to systematically investigate the thermal quenching performance of Tb3+-activated green-emitting phosphors with varying concentration gradients of Gd1-xTaO4:xTb3+ (x = 0.1%, 0.5%, and 2%) in this study. The IVCT energy levels were determined according to the empirical formula to show a decreasing trend, consistent with the position of the IVCT energy levels measured in the excitation and diffuse reflectance spectra. Moreover, the thermal quenching performance of different wavelength excitation positions (host absorption, 4f-5d of Tb3+, and Tb3+-Ta5+ IVCT band) is quite different. The modulation of thermal quenching performance among distinct phosphors when subjected to host excitation or IVCT excitation can be elucidated through optimal positions within the energy levels associated with IVCT. The diverse concentration gradient samples exhibit varying degrees of thermal quenching performance in the variable-temperature spectra. The fluorescence lifetimes of the samples are generally comparable but slightly lower. The quantum efficiency rapidly improves as the Tb concentration increases. The underlying mechanism governing this phenomenon is elucidated by constructing a model that encapsulates the interplay between the compensating and quenching channels, in addition to the energy conversion of Tb3+ into Gd3+. The abovementioned results indicate that the dual driving scheme of the doping concentration and excitation wavelength is an effective means to regulate the thermal quenching performance of Tb-activated green-emitting tantalate phosphors.