Search

• A new hybrid composite structure containing CNTRC and matrix cracked FRC layers is presented to model damaged blades. • A meshless based computational framework is proposed for nonlinear vibration behaviors of the hybrid composite blade. • The matrix cracks are revealed to have larger effect on the higher order frequency than the first order frequency. • The nonlinear vibration of cracked blade with a larger pretwisted angle is less sensitive to the deflection. A modeling of the large amplitude free vibration of pretwisted hybrid composite blades is studied by considering the laminated structure which is composed of carbon nanotube reinforced composite (CNTRC) layers and matrix cracked fiber reinforced composite (FRC) layers. Two assumptions are made to facilitate this vibration study of hybrid nanocomposite: (1) CNTs are distributed across the layer thickness uniformly or functionally graded, and (2) the parallel slit matrix cracks disperse in the matrix homogeneously. Based on the theory of differential geometry, a novel shell model for pretwisted hybrid nanocomposites blade is developed. The von Kármán strains are adopted to capture the geometrically nonlinear behaviors of blades. The established governing equations are solved accurately and efficiently via the IMLS-Ritz method. The proposed numerical model is verified by making comparison studies and then the influence of crack density, pretwisted angle, CNT distribution and volume fraction, aspect ratio, width-to-thickness ratio, and ply-angle on the large amplitude vibration characteristics of matrix cracked pretwisted hybrid composite blade are scrutinized systematically. The present study serves as a useful benchmark to researchers who intend do further research in this topic. [ABSTRACT FROM AUTHOR]

We aimed to investigate whether Taraxacum officinale (T. officinale) -derived exosome-like nanovesicles (ELNs) exerted hypotensive effects in intermittent hypoxia (IH)-induced hypertensive disorders and their potential mechanisms. In this study, we developed T. officinale -derived natural nanoparticles with ideal size and stable negative surface charge, containing large amount of lipids and some functional proteins. We found that ELNs effectively reduced IH-induced hypertension, exhibited local anti-inflammatory effects on intestinal tissues in a rat model of IH-induced hypertension, and reduced intestinal tissue damage, including loss of goblet cells and barrier integrity damage, and ultimately inhibited the systemic inflammatory response. In addition, we evaluated intestinal microbial composition and SCFAs content and found significant changes in the structure and diversity of intestinal microbes, where butyrate was identified as the most important cause of the overall differences in the flora. Therefore, we further evaluated whether butyrate was a key target for ELNs to exert their effects in IH-induced hypertensive disease. We found that butyrate intervention further inhibited systemic inflammatory response and vascular wall remodeling by improving the intestinal microenvironment in IH rats, thereby attenuating IH-induced hypertension. T. officinale -derived ELNs were effective in the treatment of IH-induced hypertensive disease, whereas butyrate played a major role in mediating the effects of ELNs in anti-IH-induced hypertensive disease. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite the great efficacy of indomethacin (IND) as an anti-inflammatory agent, its clinical translation has been obstructed by the water insolubility, severe side effects, and exceedingly low bioavailability. Indomethacin prodrug-based nanoparticles (NPs) combining the strengths of both nanotechnology and prodrugs that might overcome this crucial problem are presented. Here, using the carbodiimide-mediated couple reaction, IND was conjugated to clinically approved poly(ethylene glycol) (PEG) polymer via peptide linkage that was cleavaged in the presence of cathepsin B, which was significantly induced after inflammatory. The synthesized IND-PEG-IND conjugate was characterized by UV–vis, FTIR, 1 H NMR, XRD, and MALDI-TOF-MS analyses. For its intrinsic amphiphilic property, the IND prodrug self-assembled into NPs in aqueous solution and served two roles-as an anti-inflammatory prodrug and a drug carrier. The constructed IND-PEG-IND NPs had naoscaled particle size of approximately 80 nm, negative surface, spherical shape, good water-dispersity, and high and fixed drug-loading content of 20.1 wt%. In addition, IND-PEG-IND NPs demonstrated sustained and cathepsin B-controlled drug release behavior. More importantly, IND-PEG-IND NPs significantly reduced the acute totoxicity agaist normal osteoblast cells and displayed the more potent anti-inflammatory effect against macrophage cells compared to the free IND. Taken together, the nanoprodrug might exhibit increased potency for nanomedicine-prospective therapeutic use in clinical treatement of implant inflammatory diseases. [ABSTRACT FROM AUTHOR]

Proliferation of smooth muscle cells, oxidative stress, and pulmonary vasoconstriction resulting from intermittent hypoxia (IH) facilitate pulmonary hypertension (PH) in patients with obstructive sleep apnea. The role of Phosphodiesterase 4 B (PDE4B) in PH has not yet been established. Herein, we investigated whether PDE4B inhibition ameliorates experimental PH by modulating cAMP signaling. We performed an integrative analysis of PDE4B expression in Gene Expression Omnibus datasets, experimental IH-induced rat PH samples, and IH-induced pulmonary arterial smooth muscle cells (PASMCs). PDE4B expression was modulated using siRNA in vitro and a specific adeno-associated virus serotype 1 in vivo. In the databases of mouse models of IH-induced and sustained hypoxia-induced PH and in a rat model of six weeks of IH, the expression of PDE4B was up-regulated. Inhibition of PDE4B attenuated IH-induced pulmonary vascular remodeling and right ventricular hypertrophy. Our results also showed that PDE4B deficiency inhibited IH-induced proliferation of PASMCs with less mitochondrial reactive oxygen species and mitochondrial damage. Meanwhile, IH induced an increase in ATF4, which positively regulated the expression of PDE4B through transcription, and inhibition of ATF4 exerted effects similar to those of PDE4B inhibition. Mechanistically, downregulating the expression of PDE4B resulted in the activation of the cAMP/PKA/p-CREB/PGC-1α pathway in PASMCs after IH. Taken together, our present study provides evidence that inhibition of PDE4B attenuates IH-induced PH by regulating cAMP signaling. [Display omitted] [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) pollution is a great challenge for air environment management. However, macro quantitative research on VOC control technologies (VOCTs) evolution and global knowledge transfer is still lacking. Therefore, we analyzed the 6,636 global patents for VOCTs from 1961 to 2020 in the Derwent Innovation Index database to give a quantitative study, by using patent analysis methods such as text mining and technology life cycle analysis. The results showed that global patents surged from 2014 to 2018, and China held the most patents, followed by the US. Chinese 2013–2017 intensive atmospheric environment governance policy was the main possible reason for the sharp increase of VOC patents. However, very few Chinese patents were transferred. On the contrary, the US was the most important source country for transferred patents, and its main overseas markets were Europe, followed by China. Up to now, absorption and adsorption were the most mature technologies, accounting for 51% of the end-of-pipe patent. Biodegradation and membrane separation patents were active in transfer, indicating their high demand in the global market, so they may be promising technologies in the future. These findings enrich the literature on the evolution and transnational diffusion of VOCTs, and help policy-makers, scholars, and company managers better understand future research directions and the demands of the international market. [Display omitted] • Global 6,636 patents in 1961–2020 on VOCTs were evaluated quantitively. • The U.S. had the strongest VOCTPs market ties with Europe, followed by the U.S. with China. • Over half (51%) of the VOCTPs for end-of-pipe focused on adsorption and absorption. • The technologies of biodegradation and membrane separation were promising directions. [ABSTRACT FROM AUTHOR]

Abstract: Amorphous MoS2 nanoflowers assembled by lamellar nanosheets have been successfully synthesized by a facile hydrothermal method. They were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and evaluated as electrochemical catalysts in the hydrogen evolution reaction (HER). Moreover, the effect of preparation temperature was also discussed. It was found that these catalysts exhibited excellent HER activity compared to commercial bulk MoS2 microparticles due to the special structure of nanoflowers assembled by nanosheets with few layers, exposing much more active sites and reducing intrinsic resistance. And the catalyst obtained at 220 °C showed the best activity with the largest exchange current density and the smallest Tafel slope of 52 mV dec−1, which made it a promising HER electrocatalyst for practical applications. [Copyright &y& Elsevier]

A comprehensive understanding of the vibration characteristics of rotating blades is critical to avoid resonance fracture. This paper presents the vibration analysis and lay-up optimization of rotating pre-twisted laminated functionally graded CNTs reinforced composite (FG-CNTRC) shallow conical shells. A numerical shallow conical shell model is proposed, and the displacement fields of the shell model are described via the first-order shear deformation theory. Considering the rotating speed, the governing equation of the rotating pre-twisted laminated conical shell is derived, and then solved using the meshless kp-Ritz method. We carry out the comparison studies to demonstrate the accuracy and efficiency of the present model in dealing with the vibrations of this kind of structures. Detailed parametric studies are then performed and demonstrate that the CNT configuration, pre-twisted angle, and stacking sequence play essential roles in vibration behaviors of rotating FG-CNTRC blade. With the nondimensional frequency parameter being the optimization objective function, a genetic algorithm is employed to search for the optimal layering sequence of the rotating shallow conical shells. The optimized results demonstrate that the GA serves as a useful tool for sequence optimization of rotating blade in terms of improving the vibration characteristics. [ABSTRACT FROM AUTHOR]

This study was undertaken to examine the regulatory role of multidrug resistance-associated protein 4 (MRP4) in an experimental model of sepsis-induced acute lung injury in rats. Sepsis was induced by cecal ligation and puncture in anesthetized rats. Animals were then randomly assigned to receive intravenous injection of vehicle or MRP4 inhibitor (MK571, 20 mg/kg). The pathological changes were observed by hematoxylin and eosin staining. Lung water content, lung vascular permeability and inflammatory cell count in bronchoalveolar lavage fluid (BALF) were quantified. Serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were measured. In addition, lung tissue cyclic adenosine monophosphate (cAMP) levels were examined by enzyme-linked immunosorbent assay. Furthermore, the effects of MRP4 knockdown on lipopolysaccharide (LPS)-induced endothelial permeability and the cytoskeleton of rat pulmonary microvascular endothelial cells (PMVECs) were detected. The protein expression levels of MRP4, Rac1, VE-cadherin, β-catenin and ZO-1 were measured by Western blot analysis. MK571 significantly reduced lung tissue damage, lung water content and lung vascular permeability. Lung tissue cAMP levels were attenuated in MK571-treated animals compared with vehicle controls. MK571 also decreased sepsis-induced inflammatory cell accumulation in BALF. In addition, the MK571 group had significantly lower serum TNF-α and IL-6 levels compared with vehicle controls. Consistently, knockdown of MRP4 protected against LPS-induced increase in the endothelial permeability and the destruction of cytoskeleton in vitro. Furthermore, silencing MRP4 gene significantly reduced MRP4 protein expression and restored the protein expression of Rac1, VE-cadherin, β-catenin and ZO-1 in rat PMVECs in response to LPS stimulation. These data suggest that inhibition of MRP4 significantly alleviates sepsis-induced acute lung injury in rats. • Multidrug resistance-associated protein 4 (MRP4) is a critical regulator of sepsis-induced acute lung injury (ALI). • Inhibition of MRP4 significantly alleviates sepsis-induced ALI in rats. • The protective effect of MRP4 inhibition on sepsis-induced ALI is mainly via maintaining endothelial barrier function. [ABSTRACT FROM AUTHOR]

Depression and anxiety are prevalent in patients with idiopathic pulmonary fibrosis (IPF). Recent researchers reveal that intermittent hypoxia (IH) increases the severity of bleomycin (BLM)-induced lung injury. However, experimental studies dealing with anxiety- and depression-like behavior in animal models of BLM-induced pulmonary fibrosis in a combination of IH are lacking, hence, this study aimed to investigate that. In this study, 80 C57BL/6J male mice were intratracheally injected with BLM or normal saline at day0 and then exposed to IH (alternating cycles of FiO 2 21 % for 60 s and FiO 2 10 % for 30 s, 40 cycles/hour, 8 h/day) or intermittent air (IA) for 21 days. Behavioral tests, including open field test (OFT), sucrose preference test (SPT) and tail suspension test (TST), were detected from day22 to day26. This study found that pulmonary fibrosis developed and lung inflammation were activated in BLM-induced mice, which were potentiated by IH. Significant less time in center and less frequency of entries in the centre arena in OFT were observed in BLM treated mice, and IH exposure further decreased that. Marked decreased percent of sucrose preference in SPT, and significant increased immobility time of the TST were detected in BLM treated mice and IH widen the gaps. The expression of ionized calcium-binding adaptor molecule (Iba1) was activated in the hippocampus of BLM instillation mice and IH enlarged it. Moreover, a positive correlation between hippocampal microglia activation and inflammatory factors was observed. Our results demonstrated that IH exacerbated depressive and anxiety-like behaviors in the BLM-induced pulmonary fibrosis mice. The changes in pulmonary inflammation-hippocampal microglia activation may be a potential mechanism in this phenomenon, which can be researched in future. • Depressive and anxiety-like behavior tests were performed in the double hit mice model. • Depressive and anxiety-like behaviors were observed in BLM-induced fibrosis mice. • IH exposure exacerbated the depressive and anxiety-like behaviors. • Inflammation-hippocampal microglial activation may be potential mechanism. [ABSTRACT FROM AUTHOR]