Free-space optical (FSO) links offer gigabit per second data rates and low system complexity, but suffer from atmospheric loss due to fog and scintillation. Radio-frequency (RF) links have lower data ...rates, but are relatively insensitive to weather. Hybrid FSO/RF links combine the advantages of both links. Currently, selection or "hard-switching" is performed between FSO or RF links depending on feedback from the receiver. This technique is inefficient since only one medium is used at a time. In this paper, we develop a "soft-switching" scheme for hybrid FSO/RF links using short-length Raptor codes. Raptor encoded packets are sent simultaneously on both links and the code adapts to the conditions on either link with very limited feedback. A set of short-length Raptor codes (κ = 16 to 1024) are presented which are amenable to highspeed implementation. A practical Raptor encoder and decoder are implemented in an FPGA and shown to support a 714 Mbps data rate with a 97 mW power consumption and 26360 gate circuit scale. The performance of the switching algorithms is simulated in a realistic channel model based on climate data. For a 1 Gbps FSO link combined with a 96 Mbps WiMAX RF link, an average rate of over 472 Mbps is achieved using the implemented Raptor code while hard-switching techniques achieved 112 Mbps on average.
Abstract
A large guide-field (∼1.1
B
o
) reconnection
X
-line, observed by the Magnetospheric Multiscale spacecraft during an outbound magnetopause crossing, is studied for Alfvén waves. Here
B
o
is ...the reconnecting field magnitude. The current sheet thickness of the magnetopause was ∼2.6 ion inertial lengths (∼269 km), where field-aligned counter-streaming electrons were observed and Hall electromagnetic fields were identified. A remarkable finding was that a kinetic Alfvén wave (KAW) was seen in the magnetopause upstream region after a shear Alfvén wave (SAW) was encountered in the magnetopause layer. The presence of both the SAW and KAW near the reconnection
X
-line is for the first time reported. In the spacecraft frame of reference, the SAW has a dominant frequency at ∼0.74 Hz, while the KAW has two dominant frequencies at ∼0.38 and ∼0.64 Hz. The wave energy for KAW and SAW was mostly carried away from the reconnection site by the Poynting flux parallel to the magnetic field. The parallel temperatures for ions and electrons were increased at KAW. The peaks of
T
∥
/
T
⊥
for ions were located near the wave peaks, while the ratio peaks for electrons were near the wave troughs. Our findings suggest that KAWS and SAWs can be generated by asymmetric reconnection with a large guide field.
As one of the main functional forms of mesenchymal stem cells (MSCs), MSC-derived extracellular vesicles (MSC-EVs) have shown an alternative therapeutic option in experimental models of allergic ...asthma. Oxygen concentration plays an important role in the self-renewal, proliferation, and EV release of MSCs and a recent study found that the anti-asthma effect of MSCs was enhanced by culture in hypoxic conditions. However, the potential of hypoxic MSC-derived EVs (Hypo-EVs) in asthma is still unknown.
BALB/c female mice were sensitized and challenged with ovalbumin (OVA), and each group received PBS, normoxic human umbilical cord MSC-EVs (Nor-EVs), or Hypo-EVs weekly. After treatment, the animals were euthanized, and their lungs and bronchoalveolar lavage fluid (BALF) were collected. With the use of hematoxylin and eosin (HE), periodic acid-Schiff (PAS) and Masson's trichrome staining, enzyme-linked immune sorbent assay (ELISA), Western blot analysis, and real-time PCR, the inflammation and collagen fiber content of airways and lung parenchyma were investigated.
Hypoxic environment can promote human umbilical cord MSCs (hUCMSCs) to release more EVs. In OVA animals, the administration of Nor-EVs or Hypo-EVs significantly ameliorated the BALF total cells, eosinophils, and pro-inflammatory mediators (IL-4 and IL-13) in asthmatic mice. Moreover, Hypo-EVs were generally more potent than Nor-EVs in suppressing airway inflammation in asthmatic mice. Compared with Nor-EVs, Hypo-EVs further prevented mouse chronic allergic airway remodeling, concomitant with the decreased expression of pro-fibrogenic markers α-smooth muscle actin (α-SMA), collagen-1, and TGF-β1-p-smad2/3 signaling pathway. In vitro, Hypo-EVs decreased the expression of p-smad2/3, α-SMA, and collagen-1 in HLF-1 cells (human lung fibroblasts) stimulated by TGF-β1. In addition, we showed that miR-146a-5p was enriched in Hypo-EVs compared with that in Nor-EVs, and Hypo-EV administration unregulated the miR-146a-5p expression both in asthma mice lung tissues and in TGF-β1-treated HLF-1. More importantly, decreased miR-146a-5p expression in Hypo-EVs impaired Hypo-EV-mediated lung protection in OVA mice.
Our findings provided the first evidence that hypoxic hUCMSC-derived EVs attenuated allergic airway inflammation and airway remodeling in chronic asthma mice, potentially creating new avenues for the treatment of asthma.
Abstract Galangin is an active pharmacological ingredient from propolis and Alpinia officinarum Hance , and has been reported to have anti-cancer and antioxidative properties. Berberine, a major ...component of Berberis vulgaris extract, exhibits potent anti-cancer activities through distinct molecular mechanisms. However, the anticancer effect of galangin in combination with berberine is still unknown. In the present study, we demonstrated that the combination of galangin with berberine synergistically resulted in cell growth inhibition, apoptosis and cell cycle arrest at G2/M phase with the increased intracellular reactive oxygen species (ROS) levels in oesophageal carcinoma cells. Pretreatment with ROS scavenger promoted the apoptosis dramatically induced by co-treatment with galangin and berberine. Treatment with galangin and berberine alone caused the decreased expressions of Wnt3a and β-catenin. Interestingly, combination of galangin with berberine could further suppress Wnt3a and β-catenin expression and induce apoptosis in cancer cells. Additionally, in nude mice with xenograft tumors, the combinational treatment of galangin and berberine significantly inhibited the tumor growth without obvious toxicity. Overall, galangin in combination with berberine presented outstanding synergistic anticancer role in vitro and in vivo, indicating that the beneficial combination of galangin and berberine might provide a promising treatment for patients with oesophageal carcinoma.
The effects of paper waste (PW) ratio on biogas production by two-stage thermophilic anaerobic co-digestion (coAD) of food waste (FW) and PW, two main components of organic fraction of municipal ...solid waste, were evaluated in lab-scale continuously stirred tank systems with semi-continuous feeding. Four PW ratios (0, 20, 40, and 50%) were studied in the test. The experimental results showed the two-stage thermophilic coAD could operate stably after an adjustment period at all PW ratios. Although the increase of PW ratio decreased methane content, production and yield, reaction rates of four AD steps, it could increase the methane production of substrate when the FW was fixed. The pH, total volatile fatty acids, total alkalinity, and total ammonium of the sludge in the second stage of AD, also decreased with the increase of PW ratio in the test. The change of the substrate's organic composition, increase of carbohydrate and decrease of protein and lipid, were the main reason for the decrease of methane content, production and yield and changes of the second stage sludge characteristics. An apposite PW ratio (PW-20%) could enhance the degradation of matters (TS, VS and TCOD).
•Increase of PW ratio decrease the of biogas and methane yield of mixture.•Increase of PW ratio increase the methane production when FW was fixed.•Some characteristics of second stage sludge decreased with increase of PW ratio.•20% of PW ratio could enhance the degradation of matters (TS, VS and TCOD).•Changes of organic composition were the main reason for experimental result.
In order to study the erosion of a pipe wall via a liquid–solid suspension flow, a two-phase flow model combined with an erosion forecasting model for multiparticle impact on horizontal pipe wall ...surfaces was established in this work on the basis of low-cycle fatigue theory. In the model establishment process, the effects of particle motion and material damage were considered, and a simplified method for predicting horizontal wall erosion was obtained. The calculated results showed that the particles impact the wall at a small angle of most liquid flow velocities, causing cutting erosion damage of the wall. The settling velocity and fluctuating velocity of the particles together determine the radial velocity of the particles, which affects the impact angle of the particles. The cutting erosion caused by the small-angle impact of the particles in the pipe is more likely to cause rapid loss of the wall material. Therefore, the pipe wall is usually evenly thinned.
Attention on semiconductor nanocrystals have been largely focused because of their unique optical and electrical properties, which can be applied as light absorber and luminophore. However, the band ...gap and structure engineering of nanomaterials is not so easy because of their finite size. Here we demonstrate an approach for preparing ternary AgInS2 (AIS), quaternary AgZnInS (AZIS), AgInS2/ZnS and AgZnInS/ZnS nanocompounds based on cation exchange. First, pristine Ag2S quantum dots (QDs) with different sizes were synthesized in one-pot, followed by the partial cation exchange between In3+ and Ag+. Changing the initial ratio of In3+ to Ag+, reaction time and temperature can control the components of the obtained AIS QDs. Under the optimized conditions, AIS QDs were obtained for the first time with a cation disordered cubic phase and high photoluminescence (PL) quantum yield (QY) up to 32% in aqueous solution, demonstrating the great potential of cation exchange in the synthesis for nanocrystals with excellent optical properties. Sequentially, Zn2+ ions were incorporated in situ through a second exchange of Zn2+ to Ag+/In3+, leading to distinct results under different reaction temperature. Addition of Zn2+ precursor at room temperature produced AIS/ZnS core/shell NCs with successively enhancement of QY, while subsequent heating could obtain AZIS homogeneous alloy QDs with a successively blue-shift of PL emission. This allow us to tune the PL emission of the products from 483 to 675 nm and fabricate the chemically stable QDs core/ZnS shell structure. Based on the above results, a mechanism about the cation exchange for the ternary nanocrystals of different structures was proposed that the balance between cation exchange and diffusion is the key factor of controlling the band gap and structure of the final products. Furthermore, photostability and in vitro experiment demonstrated quite low cytotoxicity and remarkably promising applications in the field of clinical diagnosis.
This study introduces a novel organosilicon-modified polysaccharide (Si-AP) synthesized via grafting and comprehensively evaluates its performance in water-based drilling fluids (WBDFs). The ...molecular structure of Si-AP was characterized using Fourier-transform infrared spectroscopy (FTIR) and 1H-NMR experiments. Thermalgravimetric analysis (TGA) confirmed the good thermal stability of Si-AP up to 235 °C. Si-AP significantly improves the rheological properties and fluid loss performance of WBDFs. With increasing Si-AP concentration, system viscosity increases, API filtration rate decreases, clay expansion is inhibited, and drilling cuttings hydration dispersion is suppressed, especially under high-temperature conditions. Additionally, mechanistic analysis indicates that the introduction of siloxane groups can effectively inhibit the thermal degradation of AP chains and enhance their high-temperature resistance. Si-AP can form a lubricating film by adsorbing on the surface of clay particles, improving mud cake quality, reducing the friction coefficient, and significantly enhancing the lubricating performance of WBDFs. Overall, Si-AP exhibits a higher temperature-resistance limit compared to AP and more effectively optimizes the lubrication, inhibition, and control of the filtration rate of WBDFs under high-temperature conditions. While meeting the requirements of drilling fluid systems under high temperatures, Si-AP also addresses environmental concerns and holds promise as an efficient solution for the exploitation of deep-seated oil and gas resources.
We fabricated sulfur and nitrogen codoped cyanoethyl cellulose‐derived carbons (SNCCs) with state‐of‐the‐art electrochemical performance for potassium ion battery (PIB) and potassium ion capacitor ...(PIC) anodes. At 0.2, 0.5, 1, 2, 5, and 10 A g−1, the SNCC shows reversible capacities of 369, 328, 249, 208, 150, and 121 mA h g−1, respectively. Due to a high packing density of 1.01 g cm−3, the volumetric capacities are also uniquely favorable, being 373, 331, 251, 210, 151, and 122 mA h cm−3 at these currents, respectively. SNCC also shows promising initial Coulombic efficiency of 69.0% and extended cycling stability with 99.8% capacity retention after 1000 cycles. As proof of principle, an SNCC‐based PIC is fabricated and tested, achieving 94.3 Wh kg−1 at 237.5 W kg−1 and sustaining over 6000 cycles at 30 A g−1 with 84.5% retention. The internal structure of S and N codoped SNCC is based on highly dilated and defective graphene sheets arranged into nanometer‐scale walls. Using a baseline S‐free carbon for comparison (termed NCC), the role of S doping and the resultant dilated structure was elucidated. According to galvanostatic intermittent titration technique and electrochemical impedance spectroscopy analyses, as well as COMSOL simulations, this structure promotes rapid solid‐state diffusion of potassium ions and a solid electrolyte interphase that is stable during cycling. X‐ray diffraction was used to probe the ion storage mechanisms in SNCC, establishing the role of reversible potassium intercalation and the presence of KC36, KC24, and KC8 phases at low voltages.
A scalable approach is designed to fabricate dense, low‐surface‐area N, S codoped carbon (SNCC). Also, SNCC achieves high gravimetric and volumetric capacities, high initial Coulombic efficiency, and extended cycling stability. Fast K+ diffusion is promoted by the S doping and the resultant dilated structure.
PDF
