215 resultados para activated macrophages
Resumo:
This study describes the utilization of deep eutectic solvents (DESs) based on the mixture of the N-methylacetamide (MAc) with a lithium salt (LiX, with X = bis[(trifluoromethyl)sulfonyl]imide, TFSI; hexafluorophosphate, PF6; or nitrate, NO3) as electrolytes for carbon-based supercapacitors at 80 °C. The investigated DESs were formulated by mixing a LiX with the MAc (at xLi = 0.25). All DESs show the typical eutectic characteristic with eutectic points localized in the temperature range from −85 to −52 °C. Using thermal properties measured by differential scanning calorimetry (DSC), solid–liquid equilibrium phase diagrams of investigated LiX–MAc mixtures were then depicted and also compared with those predicted by using the COSMOThermX software. However, the transport properties of selected DESs (such as the conductivity (σ) and the fluidity (η–1)) are not very interesting at ambient temperature, while by increasing the temperature up to 80 °C, these properties become more favorable for electrochemical applications, as shown by the calculated Walden products: w = ση–1 (mS cm–1 Pa–1 s–1) (7 < w < 16 at 25 °C and 513 < w < 649 at 80 °C). This “superionicity” behavior of selected DESs used as electrolytes explains their good cycling ability, which was determined herein by cyclic voltammetry and galvanostic charge–discharge methods, with high capacities up to 380 F g–1 at elevated voltage and temperature, i.e., ΔE = 2.8 V and 80 °C for the LiTFSI–MAc mixture at xLi = 0.25, for example. The electrochemical resistances ESR (equivalent series resistance) and EDR (equivalent diffusion resistance) evaluated using electrochemical impedance spectroscopy (EIS) measurements clearly demonstrate that according to the nature of anion, the mechanism of ions adsorption can be described by pure double-layer adsorption at the specific surface or by the insertion of desolvated ions into the ultramicropores of the activated carbon material. The insertion of lithium ions is observed by the presence of two reversible peaks in the CVs when the operating voltage exceeds 2 V. Finally, the efficiency and capacitance of symmetric AC/AC systems were then evaluated to show the imbalance carbon electrodes caused by important lithium insertion at the negative and by the saturation of the positive by anions, both mechanisms prevent in fact the system to be operational. Considering the promising properties, especially their cost, hazard, and risks of these DESs series, their introduction as safer electrolytes could represent an important challenge for the realization of environmentally friendly EDLCs operating at high temperature.
Resumo:
Alkali activated slag (AAS) is a credible alternative to Portland cement (PC) based binder systems. The superior strength gain and low embodied carbon make it a potential binder for next generation concretes. However there is little known about the long term durability of AAS systems, especially the chloride transport and subsequent corrosion of reinforcing steel.
In this study, chloride transport through 12 AAS concretes with different alkali concentrations (Na2O% of mass of slag) and different modulus (Ms) of sodium silicate solution activator was investigated. A non-steady state chloride diffusion test was used for this study due to its similarity to the real exposure environment in terms of chloride transport through concrete. The results showed that the chloride concentration at the surface (Cs) of AAS concretes was higher than that for PC concrete.
However, lower non-steady state chloride diffusion coefficient (Dnssd) was obtained for the AAS concretes. The Dnssd of the AAS concretes decreased with the increase of Na2O% and Ms of 1.50 gave the lowest Dnssd. The results are encouraging and it can be concluded that AAS concrete offers a superior performance in terms of chloride transport.
Resumo:
Visible-light-activated yellow amorphous TiO2 (yam- TiO 2) was synthesised by a simple and organic-free precipitation method. TiN, an alternative precursor for TiO2 preparation, was dissolved in hydrogen peroxide under acidic condition (pH∼1) adjusted by nitric acid. The yellow precipitate was obtained after adjusting pH of the resultant red brown solution to 2 with NH4OH. The BET surface area of this sample was 261 m2/g. The visible light photoactivity was evaluated on the basis of the photobleaching of methylene blue (MB) in an aqueous solution by using a 250 W metal halide bulb equipped with UV cutoff filter (λ>420 nm) under aerobic conditions. Yam- TiO2 exhibits an interesting property of being both surface adsorbent and photoactive under visible light. It was assigned to the η2-peroxide, an active intermediate form of the addition of H2O2 into crystallined TiO2 photocatalyst. It can be concluded that an active intermediate form of titanium peroxo species in photocatalytic process can be synthesised and used as a visible-light-driven photocatalyst
Resumo:
A fully functioning immune system is essential in order to maintain good health. However, the immune system deteriorates with advancing age, and this contributes to increased susceptibility to infection, autoimmunity, and cancer in the older population. Progress has been made in identifying age-related defects in the adaptive immune system. In contrast, relatively little research has been carried out on the impact of ageing on the innate immune response. This area requires further research as the innate immune system plays a crucial role in protection against infection and represents a first line of defence. Macrophages are central effector cells of the innate immune system and have many diverse functions. As a result, age-related impairments in macrophage function are likely to have important consequences for the health of the older population. It has been reported that ageing in macrophages impacts on many processes including toll-like receptor signalling, polarisation, phagocytosis, and wound repair. A detailed understanding of the impact of ageing on macrophages is required in order to develop therapeutics that will boost immune responses in the older population.
Resumo:
Klebsiella pneumoniae is an important cause of community-acquired and nosocomial pneumonia. Evidence indicates that Klebsiella might be able to persist intracellularly within a vacuolar compartment. This study was designed to investigate the interaction between Klebsiella and macrophages. Engulfment of K. pneumoniae was dependent on host cytoskeleton, cell plasma membrane lipid rafts and the activation of PI 3-kinase (PI3K). Microscopy studies revealed that K. pneumoniae resides within a vacuolar compartment, the Klebsiella containing vacuolae (KCV), which traffics within vacuoles associated with the endocytic pathway. In contrast to UV-killed bacteria, the majority of live bacteria did not colocalize with markers of the lysosomal compartment. Our data suggest that K. pneumoniae triggers a programmed cell death in macrophages displaying features of apoptosis. Our efforts to identify the mechanism(s) whereby K. pneumoniae prevents the fusion of the lysosomes to the KCV uncovered the central role of the PI3K-Akt-Rab14 axis to control the phagosome maturation. Our data revealed that the capsule is dispensable for Klebsiella intracellular survival if bacteria were not opsonized. Furthermore, the environment found by Klebsiella within the KCV triggered the downregulation of the expression of cps. Altogether, this study proves evidence that K. pneumoniae survives killing by macrophages by manipulating phagosome maturation which may contribute to Klebsiella pathogenesis.
