Frequency-modulated continuous-wave synthetic-aperture radar: improvements in signal processing

With the advance of solid state devices, frequency-modulated continuous-wave (FMCW) designs have recently been used in synthetic-aperture radar (SAR) to decrease cost, size, weight and power consumption, making it deployable on smaller mobile plat-forms, including small (< 25 kg) unmanned aerial vehicle(s) (UAV). To foster its mobile uses, several SAR capabilities were studied: moving target indication (MTI) for increased situational awareness, bistatic operation, e.g. in UAV formation flights, for increased range, and signal processing algorithms for faster real-time performance. Most off-the-shelf SAR systems for small mobile platforms are commercial proprie-tary and/or military (ITAR, International Trades in Arms Regulations) restricted. As such, it necessitated the design and build of a prototype FMCW SAR system at the early stage to serve as a research tool. This enabled unrestricted hardware and software modifica-tions and experimentation. A model to analyze the triangularly modulated (TM) linear frequency modulated (LFM) waveform as one signal was established and used to develop a MTI algorithm which is effective for slow moving targets detection. Experimental field data collected by the prototyped FMCW SAR was then used to validate and demonstrate the effectiveness of the proposed MTI method. A bistatic FMCW SAR model was next introduced: Bistatic configuration is a poten-tial technique to overcome the power leakage problem in monostatic FMCW SAR. By mounting the transmitter and receiver on spatially separate mobile (UAV) platforms in formation deployment, the operation range of a bistatic FMCW SAR can be significantly improved. The proposed approximation algorithm established a signal model for bistatic FMCW SAR by using the Fresnel approximation. This model allows the existing signal processing algorithms to be used in bistatic FMCW SAR image generation without sig-nificant modification simplifying bistatic FMCW SAR signal processing. The proposed range migration algorithm is a versatile and efficient FMCW SAR sig-nal processing algorithm which requires less memory and computational load than the traditional RMA. This imaging algorithm can be employed for real-time image genera-tion by the FMCW SAR system on mobile platforms. Simulation results verified the pro-posed spectral model and experimental data demonstrated the effectiveness of the modi-fied RMA

Genipin suppression of growth and metastasis in hepatocellular carcinoma through blocking activation of STAT-3

This work is licensed under a Creative Commons Attribution 4.0 International License.Background The signal transducer and activator of transcription-3 (STAT-3) can facilitate cancer progression and metastasis by being constitutively active via various signaling. Abundant evidence has indicated that STAT-3 may be a promising molecular target for cancer treatment. Methods In this study, a dual-luciferase assay-based screening of 537 compounds for STAT-3 inhibitors of hepatocellular carcinoma (HCC) cells was conducted, leading to the identification of genipin. Effects of genipin on HCC were assessed in a patient-derived xenograft nude mice model. Western blotting assay, chromatin immunoprecipitation (ChIP) assay, molecular docking study, tube formation assay, three-dimensional top culture assay, histological examination, and immunofluorescence were utilized to evaluate the regulatory signaling pathway. Results Our research demonstrated that genipin suppresses STAT-3 phosphorylation and nuclear translocation, which may be attributed to the binding capacity of this compound to the Src homology-2 (SH2) domain of STAT-3. In addition, the therapeutic effects of genipin in a patient-derived HCC xenograft nude mice model were also demonstrated. Conclusions In conclusion, genipin showed therapeutic potential for HCC treatment by interacting with the SH2-STAT-3 domain and suppressing the activity of STAT-3. In the future, further research is planned to explore the potential role of genipin in combination with chemotherapy or radiotherapy for HCC.Xing-lin Foundation (GZF-1366732 K)NIH NS7943

Resveratrol Derivative, Trans-3, 5, 4-Trimethoxystilbene Sensitizes Osteosarcoma Cells to Apoptosis via ROS-Induced Caspases Activation

Numerous studies have shown that resveratrol can induce apoptosis in cancer cells. Trans-3, 5, 4-trimethoxystilbene (TMS), a novel derivative of resveratrol, is a more potent anticancer compound than resveratrol and can induce apoptosis in cancer cells. Herein, we examined the mechanisms involved in TMS-mediated sensitization of human osteosarcoma (143B) cells to TNF-related apoptosis-inducing ligand- (TRAIL-) induced apoptosis. Our results showed that cotreatment with TSM and TRAIL activated caspases and increased PARP-1 cleavage in 143B cells. Decreasing cellular ROS levels using NAC reversed TSM- and TRAIL-induced apoptosis in 143B cells. NAC abolished the upregulated expression of PUMA and p53 induced by treatment with TRAIL and TSM. Silencing the expression of p53 or PUMA using RNA interference attenuated TSM-mediated sensitization of 143B cells to TRAIL-induced apoptosis. Knockdown of Bax also reversed TSM-induced sensitization of 143B cell to TRAIL-mediated apoptotic cell death. These results indicate that cotreatment with TRAIL and TSM evaluated intracellular ROS level, promoted DNA damage, and activated the Bax/PUMA/p53 pathway, leading to activation of both mitochondrial and caspase-mediated apoptosis in 143B cells. Orthotopic implantation of 143B cells in mice also demonstrated that cotreatment with TRAIL and TSM reversed resistance to apoptosis in cells without obvious adverse effects in normal cells

Development and validation of a preoperative MRI-based radiomics nomogram to predict progression-free survival in patients with clival chordomas

ObjectivesThe aim of this study was to establish and validate a MRI-based radiomics nomogram to predict progression-free survival (PFS) of clival chordoma.MethodsA total of 174 patients were enrolled in the study (train cohort: 121 cases, test cohort: 53 cases). Radiomic features were extracted from multiparametric MRIs. Intraclass correlation coefficient analysis and a Lasso and Elastic-Net regularized generalized linear model were used for feature selection. Then, a nomogram was established via univariate and multivariate Cox regression analysis in the train cohort. The performance of this nomogram was assessed by area under curve (AUC) and calibration curve.ResultsA total of 3318 radiomic features were extracted from each patient, of which 2563 radiomic features were stable features. After feature selection, seven radiomic features were selected. Cox regression analysis revealed that 2 clinical factors (degree of resection, and presence or absence of primary chordoma) and 4 radiomic features were independent prognostic factors. The AUC of the established nomogram was 0.747, 0.807, and 0.904 for PFS prediction at 1, 3, and 5 years in the train cohort, respectively, compared with 0.582, 0.852, and 0.914 in the test cohort. Calibration and risk score stratified survival curves were satisfactory in the train and test cohort.ConclusionsThe presented nomogram demonstrated a favorable predictive accuracy of PFS, which provided a novel tool to predict prognosis and risk stratification. Our results suggest that radiomic analysis can effectively help neurosurgeons perform individualized evaluations of patients with clival chordomas

Physical Methods for the Preparation of Hybrid Nanocomposite Polymer Latex Particles

In this chapter, we will highlight conceptual physical approaches towards the fabrication of nanocomposite polymer latexes in which each individual latex particle contains one or more "hard" nanoparticles, such as clays, silicates, titanates, or other metal(oxides). By "physical approaches" we mean that the "hard" nanoparticles are added as pre-existing entities, and are not synthesized in situ as part of the nanocomposite polymer latex fabrication process. We will narrow our discussion to focus on physical methods that rely on the assembly of nanoparticles onto the latex particles after the latex particles have been formed, or its reciprocal analogue, the adhesion of polymer onto an inorganic nanoparticle. First, will discuss the phenomenon of heterocoagulation and its various driving forces, such as electrostatic interactions, the hydrophobic effect, and secondary molecular interactions. We will then address methods that involve assembly of nanoparticles onto or around the more liquid precursors (i.e., swollen/growing latex particles or monomer droplets). We will focus on the phenomenon of Pickering stabilization. We will then discuss features of particle interaction with soft interfaces, and see how the adhesion of particles onto emulsion droplets can be applied in suspension, miniemulsion, and emulsion polymerization. Finally, we will very briefly mention some interesting methods that make use of interface-driven templating for making well-defined assembled clusters and supracolloidal structures

Focusing Bistatic FMCW SAR Signal by Range Migration Algorithm Based on Fresnel Approximation

Frequency modulated continuous wave (FMCW) technique has recently been employed by synthetic aperture radar (SAR) to decrease the radar cost and volume. However, the operation range is limited by the direct energy leakage from the transmitting channel to receiving channel due to the operation principle of FMCW technique. Bistatic configuration is an efficient way to increase the isolation between the transmitter and receiver, which could significantly increase the radar standoff range. A bistatic FMCW SAR spectrum model is proposed by using the Fresnel approximation in this paper. This model is similar to that of a monostatic FMCW SAR spectrum, which allows the existing imaging algorithms to be used on bistatic image processing. Based on the new model and the characteristics of FMCW signal, a modified range migration algorithm (RMA) for FMCW SAR is proposed to focus the image, which requires less memory and computational load than the traditional RMA. Point-target simulation is used to verify the proposed spectral model and real data processing verified the effectiveness of the proposed RMA

Surface modification strategies of 304 austenitic stainless steel plate with different micromorphology and composition for improved mechanical interlocking and chemical bonding in metal–epoxy joints

304 austenitic stainless-steel (SS) strip-based carbon fiber metal laminates (CFMLs) have raised significant concerns, in terms of their mechanical performance. On top of that, the hybrid laminates’ interlamination performance is vital in regulating their failure patterns. Along these lines, in this work, SS strips with regulatable micromorphology and composition were obtained by using physical and chemical surface modification strategies, including polishing, acid etching, anodization, and thermal treatment. The shear strength of the treated-SS/epoxy single lap joints (two treated-SS strips bonded by the epoxy resin via hot curing process) was systematically explored, and the origins of the enhancement mechanism were attributed to the resulting surface microstructure, as well as the possible chemical reactions between the treated surface and the curing agent. The etching-anodizing-thermally treated-SS (EAT-SS)/epoxy joint exhibited the maximum shear strength (16.04 MPa) and work of fracture (5.85 kJ·m−2) due to the substantial cohesive failure pattern of the epoxy. The encouraging enhancement was mainly attributed to the synergistic effect of the micro-annular pit and the nanoporous array structure of the EAT-SS surface. These effects induced a significant mechanical interlock and a plausible chemical reaction at the interface, which led to improved bonding strength between the epoxy and treated-SS surface. Overall, in this work, it was demonstrated that the combination of the anodization and thermal treatment can effectively improve the interlamination bonding properties between the SS strip and the epoxy resin due to the combination effect of mechanical interlocking and chemical bonding.</p