Nonlinear error correction for Terahertz FMCW System by a new beat frequency estimation method.

Terahertz (THz) frequency modulated continuous wave (FMCW) technology is a means of nondestructive testing. The signal's nonlinearity is an unavoidable problem in the daily application of THz FMCW technology. The signal's nonlinearity will lead to the spectrum broadening of the FMCW's beat frequency (BF) signal, which degrades the range resolution and result in distance-measuring error. Traditional methods require additional hardware or require a lot of computation, which are not conducive to the miniaturization of the system and real-time measurement. A novel method for correcting the nonlinear error of THz FMCW technology has been proposed and demonstrated in this article. In the proposed method, the windowed Fourier transform (WFT) is introduced to estimate the BF corresponding to the measured target, according to the linearity distribution of voltage-controlled oscillator (VCO). In this way, the measured target's BF can be accurately estimated from the unprocessed BF signal with a poor linearity. From the estimated BF of the reference target, the non-linear compensation coefficients are calculated. With the non-linear compensation coefficients, the non-linearity of the output BF signal can be calibrated. The results of simulations and experiments show that the proposed method allows the range resolution of an FMCW system to reach the theoretical limit.

Temperature-Controlled Degree of Interpenetration in a Single-Crystal-to-Single-Crystal Transformation within Two Co(II)-Triazole Frameworks.

Four-fold interpenetrating framework 1a can be constructed driven by temperature-controlled SC-SC transformation from 2-fold interpenetrating network 1. Luminescent properties indicated that 1a can be viewed as a luminescent sensor of high-explosives.

MicroRNA-138 Aggravates Inflammatory Responses of Macrophages by Targeting SIRT1 and Regulating the NF-κB and AKT Pathways.

BACKGROUND/AIMS: With increased understanding of sepsis, mortality is decreasing. However, there is still a lack of effective therapeutic strategy. The inflammatory response of macrophages is critical during sepsis. METHODS: Macrophages were stimulated with LPS. Western blotting and qRT-PCR were used to detect inflammatory responses. Then, the inhibitor of microRNA-138 was transfected and Western blotting, qRT-PCR, H&E staining and ELISA were used to verify the role of microRNA-138 in inflammation. Then target gene prediction databases were used to predict the potential target of microRNA-138. Both animal and cell models under LPS challenges were established to verify the regulation of SIRT1 and microRNA-138 during inflammation. RESULTS: The present study showed that microRNA-138 was increased in macrophages stimulated with LPS. Additionally, the NF-κB and AKT pathways were both activated. The pre-treatment of microRNA-138 inhibitor decreased inflammatory factors, downregulated the NF-κB pathway, activated the AKT pathway and protected against organ damage in mice challenged with LPS. SIRT1 was demonstrated as a potential target of microRNA-138In macrophages stimulated with LPS, the inhibition effect of microRNA-138 inhibitor on inflammation was lost by SIRT1 siRNA pre-treatment. In the animal model, the protective effect of microRNA-138 antagomir disappeared in SIRT1 knockout mice. CONCLUSION: We demonstrated that miR-138 participated in the inflammatory process by inhibiting SIRT1 and activating the NF-κB pathway.

Method for defect contour extraction in terahertz non-destructive testing conducted with a raster-scan THz imaging system.

In this paper, a neoteric algorithm based on a two-dimensional continuous wavelet transform is developed to get the defect contour in the terahertz (THz) non-destructive testing result obtained from a raster-scan frequency-modulated continuous-wave (FMCW) THz imaging system. In order to prove the method's validity, an experiment is carried out. The result of the experiment shows that the method allows one to extract the defect contour from the THz FMCW interference with severe stripe noises. Moreover, the relative error of defect area between the actual value and that obtained from the extracted defect contour is no more than 3.03%. This means that the method provided an effective and exact way to extract a defect contour in THz FMCW interference.

[Identification of Chinese herbal medicines based on terahertz spectroscopy analysis].

In order to study the feasibility of the identification of Chinese herbal medicines based on terahertz spectroscopy, the optical characteristic of astragalus, angelica, eucommia and three kinds of astragalus samples with different impurities in the frequency range 0.2-2.2 THz were researched by terahertz time-domain spectroscopy (THz-TDS), and their time-domain spectra, the frequency spectra and the absorption spectra were obtained at room temperature. The results indicated that the time-domain spectra, frequency-domain spectra and absorption spectra of astragalus, angelica, and eucommia have large differences in such a frequency range, the frequency-domain spectra and absorption spectra of three kinds of astragalus samples with different impurities are similar but there exists distinct difference. These researches proved that it is feasible to use terahertz time-domain spectroscopy to identify Chinese herbal medicine and provided a new method for Chinese herbal medicine quality control.

Adipose Mesenchymal Stem Cell Derived Exosomes Promote Keratinocytes and Fibroblasts Embedded in Collagen/Platelet-Rich Plasma Scaffold and Accelerate Wound Healing.

Engineered skin substitutes derived from human skin significantly reduce inflammatory reactions mediated by foreign/artificial materials and are consequently easier to use for clinical application. Type I collagen is a main component of the extracellular matrix during wound healing and has excellent biocompatibility, and platelet-rich plasma can be used as the initiator of the healing cascade. Adipose mesenchymal stem cell derived exosomes are crucial for tissue repair and play key roles in enhancing cell regeneration, promoting angiogenesis, regulating inflammation, and remodeling extracellular matrix. Herein, Type I collagen and platelet-rich plasma, which provide natural supports for keratinocyte and fibroblast adhesion, migration, and proliferation, are mixed to form a stable 3D scaffold. Adipose mesenchymal stem cell derived exosomes are added to the scaffold to improve the performance of the engineered skin. The physicochemical properties of this cellular scaffold are analyzed, and the repair effect is evaluated in a full-thickness skin defect mouse model. The cellular scaffold reduces the level of inflammation and promotes cell proliferation and angiogenesis to accelerate wound healing. Proteomic analysis shows that exosomes exhibit excellent anti-inflammatory and proangiogenic effects in collagen/platelet-rich plasma scaffolds. The proposed method provides a new therapeutic strategy and theoretical basis for tissue regeneration and wound repair.

Pinocembrin inhibits lipopolysaccharide-induced inflammatory mediators production in BV2 microglial cells through suppression of PI3K/Akt/NF-κB pathway.

Pinocembrin, one of the primary flavonoids from Pinus heartwood and Eucalyptus, has been reported to have anti-inflammatory and antioxidant activity. This study was designed to evaluate the inhibitory effects of pinocembrin on inflammatory mediators production in LPS-stimulated BV2 microglial cells. The results showed that pinocembrin dose-dependently inhibited LPS-induced inflammatory mediators TNF-α, IL-1ß, NO and PGE2 production. Pinocembrin also inhibited LPS-induced iNOS and COX-2 expression. Moreover, pinocembrin inhibited LPS-induced PI3K, Akt phosphorylation, and NF-κB activation, which were required for inflammatory mediators production. Furthermore, treatment of pinocembrin induced nuclear translocation of Nrf2 and expression of HO-1. In conclusion, our data indicated that pinocembrin inhibited LPS-induced inflammatory mediators production by suppressing PI3K/Akt/NF-κB signaling pathway.

Experimental verification and investigation of disks scattering slab modes in metal-dielectric heterostructures.

A thin dielectric plate can support conventional slab modes such as leaky Fabry-Perot, guided waves and radiation modes. When the plate is coated on a metallic subwavelength disk array, it can result in new confined modes, hereby named 'disks scattering slab modes' (DSSMs). By use of a terahertz time-domain spectroscopy system, we experimentally verify the existence of two types of DSSMs in terahertz range: one we refer to as highly confined disks scattering Fabry-Perot-like modes (DSFPMs) and the other as, weakly confined disks scattering radiation-like modes (DSRMs). Spectral characteristics of these confined modes are measured and numerically simulated. Particularly, based on the experimental results and a dipole-scattering model developed here, we show that the features of the DSFPMs can be tuned by changing the filling fraction of the disk array. We believe these results can make important contributions to the designs of new terahertz devices, including tunable absorbers and filters.