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31.
Human β-definsin-2 (hBD-2) is mainly induced by bacterial factors and pro-inflammation mediators in epithelial cells. As the major cause of community-acquired pneumonia, whether Streptococcus pneumoniae (S. pneu-moniae) stimulation induces hBD-2 expression in airway epithelial cells is elusive. In this study, we found that S. pneumoniae stimulation induced hBD-2 expression in a time-and concentration-dependent manner in primary human airway epithelial cells. To further reveal the mechanism of S. pneumoniae inducing hBD-2, we found that S. pneumoniae stimulation activated NF-κB signaling pathway. Specific NF-κB inhibitor, PDTC, could reverse the induction of hBD-2 by S. pneumoniae. We also found that cellular inner Ca^2+ signaling is involved in the S. pneumoniae-induced hBD-2. Taken together, our find-ings indicated that S. pneumoniae can stimulate the expression of hBD-2 in airway epithelial cells and NF-κB and inositol triphosphate-dependent intracellular calcium release is involved in this induction. 相似文献
32.
Carbon nanofibers (CNFs) and MnOjc@CNF nanocomposites (MCNFs) are fabricated by electrospin- ning and investigated as free-standing electrodes for sup- ercapacitor. This work presents the effect of heating rate during carbonization on the electrochemical behavior of the as-prepared MCNFs electrodes in 6 mol/L KOH elec-trolyte. Results show that the MCNFs electrodes carbon- ized by relatively slower heating rate exhibit higher specific capacitance. The electronic conductivity of the slow heated MCNFs electrodes is better than that of the fast heated electrodes due to the better crystallinity of the MnOx nanoparticles and the graphitic carbon layers forming on the surface of the Mn-loaded CNFs. These MCNFs electrodes demonstrate elevated rate capability and improved cycling performance without adding any polymer binder or electronic conductor. 相似文献
33.
Two utility-optimization dynamic subcarrier allocation (DSA) algorithms are designed for single carrier frequency division multiple access system (SC-FDMA). The two proposed algorithms aim to support diverse transmission capacity requirements in wireless networks, which consider both the channel state information (CSI) and the capacity requirements of each user by setting appropriate utility functions. Simulation results show that with considerable lower computational complexity, the first utility-optimization algorithm can meet the system capacity requirements of each user effectively. However, the rate-sum capacity performance is poor. Furthermore, the second proposed utility-opti- mization algorithm can contribute a better trade-off between system rate-sum capacity requirement and the capacity requirements of each user by introducing the signal to noise ratio (SNR) informa- tion to the utility function based on the first utility-optimization algorithm, which can improve the us- er requirements processing capability as well as achieve a better sum-rate capacity. 相似文献
34.
Kaiting Cheng Yiming Fang Liang Bai Feng Gui Junchi Ma Huimin Gao Yadong Zhao Xingtao Xu 《自然科学进展(英文版)》2023,(5):581-592
In everyday life, traditional dressings such as band-aid and gauze are used for dealing with small wounds.However, these dressings have shortcomings such as pain caused by tearing, inapplicability to joints, single functionality, and adverse reactions. Therefore, there is a great need for an inexpensive, comfortable, and multifunctional wound dressing. In this study, quaternized chitosan(QCS) with a high degree of substitution(107.84%) was successfully prepared and characterized using ultraviole... 相似文献
35.
Hui Jiang Shibi Fang 《复旦学报(自然科学版)》2005,44(5):746-747
All solid-state polymer electrolytes for lithium battery was proved to be an attractive direction. Compared with prevenient polymer electrolytes all solid-state polymer electrolytes were superiority in more broad electrochemical window, more stable/low interracial resistance especially when situ-polymerization utilized, excellent mechanical properties and dissepiment free. A lithium secondary battery using all solid-state polymer electrolyte meet the challenge of energy source for both portable electronic devices and electric vehicles (EV) or engine/battery hybrid vehicles (HEV). All solid-state comb-like network polymer electrolytes (CNPE) based on polysiloxane with internal plasticizing chain (IPC) has been designed and synthesized. See Fig. 1. 相似文献
36.
This article summarizes the comparison between the preparation,structure and mechanical properties of long fiber reinforced thermoplastics(LFT) and short fiber reinforced thermoplastics(SFT).Both of the experiment and theory results showed that the mechanical properties of long glass fiber reinforced thermoplastics pellets(LGFRT) have been enhanced better than that of short glass fiber reinforced thermoplastics pellets(SGFRT) manufactured by molding procession.After regulation of the relative humidity by 50%,the mechanical properties of 30%(weight percent) short glass fiber content in SFT(SFT-PA6-SGF30) are similar to that of 40%long glass fiber content in LFT.However, the density of the latter is about 17%lower than that of the former.Thus,the corresponding weight of products is reduced by 13%;output rate is increased by 21%,and the cost is therefore significantly lowered.And it has the following advantages;impact strength is increased by 87%;the proportion is reduced by 20%;molding cycle is shortened by 10%;materials cost is saved by 20%~ 30%and the final total cost is saved by 30%~ 40%.So LFT (LFT-PP-LGF40 ) can replace SFT(SFT-PA6-SGF30) with the similar basic mechanical properties under normal temperature or 160℃lower. 相似文献
37.
Comparative study of different membranes as separators for rechargeable lithium-ion batteries
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Membranes of polypropylene (PP), PP coated with nano-Al2O3, PP electrospun with polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), and trilayer laminates of polypropylene-polyethylene-polypropylene (PP/PE/PP) were comparatively studied. Their physical properties were characterized by means of thermal shrinkage test, liquid electrolyte uptake, and field emission scanning electron microscopy (FESEM). Results show that, for the different membranes as PP, PP coated with nano-Al2O3, PP electrospun with PVdF-HFP, and PP/PE/PP, the thermal shrinkages are 14%, 6%, 12.6%, and 13.3%, while the liquid electrolyte uptakes are 110%, 150%, 217%, and 129%, respectively. In addition, the effects on the performance of lithium-ion batteries (LiFePO4 and LiNi1/3Co1/3Mn1/3O2 as the cathode material) were investigated by AC impedance and galvanostatic charge/discharge test. It is found that PP coated with Al2O3 and PP electrospun with PVdF-HFP can effectively increase the wettability between the cathode material and liquid electrolyte, and therefore reduce the charge transfer resistance, which improves the capacity retention and battery performance. 相似文献
38.
A Y-type hexaferrite rod with the composition of Ba2Co1.8Cu0.2Fe12O22 was presented as an absorbing material with high absorbance. Its high absorbance and wide absorption band result from ferromagnetic resonance (FMR) that is self-biased by strong shape and magnetocrystalline anisotropy fields. Around the FMR frequency the specimen of the ferrite rods exhibits very high absorbance and the FMR frequency can be tuned by the rod dimension. In addition to the high absorbance and the wide tunable absorption band, the microwave absorber has another advantage of light weight due to the use of the ferrite rods instead of ferrite slabs. 相似文献
39.
The effect of microstructure and surface chemistry on nicotine adsorption capacity of almond-shell-based activated carbon was studied.Almond-shell-based activated carbon was reactivated or modified with steam,ZnCl2and NaHSO4separately.The surface area and pore structure parameters of activated carbon were determined from the adsorption-desorption isotherm of nitrogen at 77K.Boehm titration and FTIR were explored to determine the surface oxygen groups.The results revealed that nicotine adsorption from solution on carbons depend on the micropores and phenolic groups.A strong correlation between the amounts of adsorbed nicotine and the phenolic groups was observed,whereas the higher amounts of carboxylic groups decrease the nicotine adsorption capacity on activated carbons. 相似文献
40.
Poly(allylamine hydrochloride) (PAH), which is frequently used in fabricating polyelectrolyte multilayer films, was studied by single molecule force spectroscopy (SMFS). Plenty of force-extension curves with a long plateau were obtained in water, indicating that train-like structure was predominant when PAH was adsorbed on the substrate. It was found that the peak-type force-extension curves of PAH in water were not able to be fitted by the modified freely-jointed chain model. Additionally, there was a flat region in the derivative of force-extension curves. Thus, it was inferred that PAH chain in water was in a special conformation and underwent a "conformational transition" under the stretching of an external force. This phenomenon did not appear in the SMFS experiment in 1 mol/L urea solution, which indicated that urea was able to break the special conformation. 相似文献