UAV-Assisted FSO Communication System with Amplify-and-Forward Protocol under AOA Fluctuations:A Performance Analysis

Free space optical(FSO)communication has recently aroused great interest in academia due to its unique features,such as large transmission band,high data rates,and strong anti-electromagnetic interference.With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance,we propose an unmanned aerial vehicle(UAV)-assisted dual-hop FSO communication system equipped with amplifyand-forward protocol at the relay node.Specifically,we consider impairments of atmospheric absorption,pointing errors,atmospheric turbulence,and link interruptions due to angle-of-arrival fluctuations in the relay system.The Gamma-Gamma and Malaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAVto-destination links,respectively.We derive closedform expressions of the probability density function(PDF)and cumulative distribution function(CDF)for the proposed communication system,in terms of the Meijer-G function.Based on the precise PDF and CDF,analytical expressions for the outage probability,average bit error rate,and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function.Finally,we show that there is a match between the analytical results and numerical results,and we analyze the influence of the system and channel parameters on the performance.

An Energy-Efficient UAV Deployment Scheme for Emergency Communications in Air-Ground Networks with Joint Trajectory and Power Optimization

The space-air-ground integrated network(SAGIN)has gained widespread attention from academia and industry in recent years.It is widely applied in many practical fields such as global observation and mapping,intelligent transportation systems,and military missions.As an information carrier of air platforms,the deployment strategy of unmanned aerial vehicles(UAVs)is essential for communication systems’performance.In this paper,we discuss a UAV broadcast coverage strategy that can maximize energy efficiency(EE)under terrestrial users’requirements.Due to the non-convexity of this issue,conventional approaches often solve with heuristics algorithms or alternate optimization.To this end,we propose an iterative algorithm by optimizing trajectory and power allocation jointly.Firstly,we discrete the UAV trajectory into several stop points and propose a user grouping strategy based on the traveling salesman problem(TSP)to acquire the number of stop points and the optimization range.Then,we use the Dinkelbach method to dispose of the fractional form and transform the original problem into an iteratively solvable convex optimization problem by variable substitution and Taylor approximation.Numerical results validate our proposed solution and outperform the benchmark schemes in EE and mission completion time.

Dual-Hop Deep Space-Terrestrial FSO/RF Communication under Solar Scintillation: Performance Analysis and Challenges

Deep space communication has been a fundamental guarantee for space exploration but encounters solar scintillation during superior solar conjunction.In this paper,a paradigm for deep space-terrestrial free space optical(FSO)/radio frequency(RF)communication is proposed,and the outage probability performance of the dual-hop amplify-and-forward(AF)based FSO/RF communication system is investigated.Specifically,the asymmetric dual-hop channel models are considered,where the Gamma-Gamma distribution characterizes the FSO link between the deep space probe and a relay satellite that undergoes coronal turbulence,while the RF link between the satellite and the terrestrial receiver follows the shadowed-Rician fading model due to the shadowing effect.Moreover,the closed-form expressions of the outage probability for both channel state information(CSI)-assisted and fixed gain relay systems are presented with the consideration of multiple antennas equipped on the destination,which provide practical insights to the link performance.Simulation results present the validation of our theoretical expressions and highlight a strategy for the improvement of the outage probability performance for deep space-terrestrial communication.Finally,some open issues and research directions that should be further investigated for the actual deep space communication system during superior solar conjunction are identified.

A composite peptide-supramolecular microneedle system for melanoma immunotherapy

Despite recent advances in melanoma treatment through the use of antibody immunotherapy,the clinical benefit remains restricted by its inefficient infiltration and immunosuppression within the tumor microenvironment(TME).In addition,immunerelated adverse events(irAEs)have often occurred due to the off-target binding of therapeutic drugs to normal tissues after systematic administration.Herein,we constructed an integrated and cascaded drug delivery system for the treatment of melanoma.In addition to blocking the programmed cell death protein 1 or its ligand(PD-1/PD-L1)axis,the PD-L1 targeting peptide(FE)with spherical micelle self-assembly characteristics could also effectively encapsulate the immune adjuvant resiquimod(R848),and form a complete nano drug.FE^(R)was further integrated into tumor-responsive microneedles(MNs)to establish FE^(R)@MN and could reach the cascaded functions.FE^(R)could be sustainedly released from the MN system and disassemble into monomers,achieving PD-1/PD-L1 axis blockade whilst reprogramming the immunosuppressive TME.Notably,FE^(R)@MN permits the controllable release and retention enhancement of the targeting peptide in the TME,thus causing prolonged PD-L1 blockade effect.It is demonstrated that this synergistic treatment could efficiently inhibit melanoma growth,providing a new strategy for the combination treatment of melanoma.

N6-methyladenosine modification of CENPF mRNA facilitates gastric cancer metastasis via regulating FAK nuclear export

Background:N6-methyladenosine(m^(6)A)modification is the most common modification that occurs in eukaryotes.Although substantial effort has been made in the prevention and treatment of gastric cancer(GC)in recent years,the prognosis of GC patients remains unsatisfactory.The regulatory mechanism between m^(6)A modification and GC development needs to be elucidated.In this study,we examined m^(6)A modification and the downstream mechanism in GC.Methods:Dot blotting assays,The Cancer Genome Atlas analysis,and quantitative real‑time PCR(qRT-PCR)were used to measure the m^(6)A levels in GC tissues.Methylated RNA-immunoprecipitation sequencing and RNA sequencingwere performed to identify the targets ofm^(6)Amodification.Western blotting,Transwell,wound healing,and angiogenesis assays were conducted to examine the role of centromere protein F(CENPF)in GC in vitro.Xenograft,immunohistochemistry,and in vivo metastasis experiments were conducted to examine the role of CENPF in GC in vivo.Methylated RNA-immunoprecipitation-qPCR,RNA immunoprecipitation-qPCR and RNA pulldown assays were used to verify the m^(6)A modification sites of CENPF.Gain/loss-of-function and rescue experiments were conducted to determine the relationship between CENPF and the mitogen-activated protein kinase(MAPK)signaling pathway in GC cells.Coimmunoprecipitation,mass spectrometry,qRT-PCR,and immunofluorescence assays were performed to explore the proteins that interact with CENPF and elucidate the regulatory mechanisms between them.Results:CENPF was upregulated in GC and facilitated the metastasis of GC both in vitro and in vivo.Mechanistically,increasedm^(6)A modification of CENPF was mediated by methyltransferase 3,and this modified molecule could be recognized by heterogeneous nuclear ribonucleoprotein A2/B1(HNRNPA2B1),thereby promoting its mRNA stability.In addition,the metastatic phenotype of CENPF was dependent on the MAPK signaling pathway.Furthermore,CENPF could bind to FAK and promote its localization in the cytoplasm.Moreover,we discovered that high expression of CENPF was related to lymphatic invasion and overall survival in GC patients.Conclusions:Our findings revealed that increased m^(6)A modification of CENPF facilitates the metastasis and angiogenesis of GC through the CENPF/FAK/MAPK and epithelial-mesenchymal transition axis.CENPF expression was correlated with the clinical features of GC patients;therefore,CENPF may serve as a prognostic marker of GC.

A theranostic agent for cancer therapy and imaging in the second nearinfrared window

Thera no stic nano particles are integrated systems useful for simulta neous diag nosis and imaging guided delivery of therapeutic drugs, with wide ranging pote ntial applicati ons in the clinic. Here we developed a thera no stic nan oparticle (~24 nm size by dynamic light scatteri ng) p-FE-PTX-FA based on polymeric micelle encapsulating an organic dye (FE) fluorescing in the 1,000-1,700 nm second near-infrared (NIR-Ⅱ) window and an an ti-ca ncer drug paclitaxel. Folic acid (FA) was conjugated to the nan oparticles to afford specific binding to molecular folate receptors on muri ne breast can cer 4T1 tumor cells. In vivo, the nan oparticles accumulated in 4T1 tumor through both passive and active targeting effect. Under an 808 nm laser excitation, fluorescence detection above 1,300 nm afforded a large Stokes shift, allowing targeted molecular imaging tumor with high signal to background ratios, reaching a high tumor to normal tissue signal ratio (T/NT) of (20.0±2.3). Further, 4T1 tumors on mice were completed eradicated by paclitaxel released from p-FE-PTA-FA within 20 days of the first injection. Pharmacokinetics and histology studies indicated p-FE-PTX-FA had no obvious toxic side effects to major organs. This represented the first NIR-Ⅱ theranostic age nt developed.

浮选设备流体力学特征参数研究现状

浮选设备是矿物加工工程领域一种重要的气液反应装置,主要包括浮选机和浮选柱。浮选设备应用已有百年历史,随着选矿技术水平的提高,浮选设备逐渐向自动化、大型化的方向发展。近年来对浮选设备内流体力学特征参数的研究解析越来越多,进一步促进了设备的合理放大和优化。本工作在简要介绍目前浮选设备的发展和应用现状后,总结了国内外学者对浮选设备内气泡尺寸、气含率和气泡速度3个重要流体力学特征参数的检测方法和研究现状,提出了在今后研究中,开发以机器视觉为核心的检测技术和强化侵入式检测装置的适用性是流体力学特征参数检测手段的发展方向之一。

A novel PD-L1 targeting peptide self-assembled nanofibers for sensitive tumor imaging and photothermal immunotherapy in vivo

Programmed death 1(PD-1)and its ligand PD-L1 are two typical immune checkpoints.Antibody-based immune checkpoint blockade(ICB)strategy targeting PD-1/PD-L1 achieved a significant therapeutic effect on cancer.However,due to the impenetrability of antibody drugs and the occurrence of immune-related adverse events,only a minority of patients benefit from this treatment.Peptides multimerization has been widely proved to be an effective method to improve receptor binding affinity through a multivalent synergistic effect.In this study,we report a novel peptide-aggregation-induced emission(AIE)hybrid supramolecular TAP,which can self-assemble into nanofibers through non-covalent interactions such as hydrogen bonds,with a specific nanomolar affinity to PD-L1 in vivo and in vitro.Combined with near-infrared agents,it can be used for tumor imaging and photothermal therapy,which enables photothermal ablation of cancer cells for generating tumor-associated antigen(TAA)and triggering a series of immunological events.Collectively,our work suggests that synthetic self-assembled peptide nanofibers can be developed as attractive platforms for active photothermal immunotherapies against cancer.

Graphene Nanoribbons from Tetraphenylethene-Based Polymeric Precursor： Chemical Synthesis and Application in Thin-Film Field-Effect Transistor

Graphene nanoribbons （GNRs） with a non-zero bandgap are regarded as a promising candidate for the fabrica- tion of electronic devices. In this study, large-scale solution synthesis of narrow GNRs was firstly achieved by the intramolecular cyclodehydrogenation of kinked tetraphenylethene （TPE） polymer precursors prepared by A2B2-type Suzuki-Miyaura polymerization. After the cyclization reaction, the nanoribbons have a better conjugation than the twisted polymer precursor, resulting in obvious red shift in UV/vis absorption and photoluminescence （PL） spectra. The efficient formation of conjugated nanoribbons was also investigated by Raman, FTIR spectroscopy, and micro- scopic studies. Furthermore, such structurally well-defined GNRs have been successfully developed for top-gated field-effect transistor （FET） by directly solution processing. The AFM images show that the prepared-GNRs thin films form crystalline fibrillar intercalating networks, which can effectively facilitate the charge transport. These FET devices with ion-gel gate dielectrics exhibit low-voltage operation （〈5 V） with excellent mobility up to 0.41 cm2·V-1·s-1 and an on-off ratio of 3 × 104, thus opening up new opportunities for flexible GNRs-based electronic devices.

A facile solution approach for fabrication of small-sized MoSe_(2) with few layers as an efficient hydrogen evolution electrocatalyst

Unlike fossil fuels,hydrogen is a renewable and clean energy source.It is available in a large amount and spreads throughout the world.When reacting with oxygen,hydrogen releases energy to produce water as the only product.Hence,hydrogen is a promising alternative to fossil fuels[1].Today,most of hydrogen is produced via the steam methane reforming process,in which hightemperature steam is used to produce hydrogen from a methane source.However,methane is non-renewable,and carbon dioxide is generated in the reforming process.