A stable Zr(IV)-MOF for efficient removal of trace SO2 from flue gas in dry and humid conditions.

Obtaining suitable adsorbents for selective separation of SO2 from flue gas still remains an important issue. A stable Zr(IV)-MOF (Zr-PTBA) can be conveniently synthesized through the self-assembly of a tetracarboxylic acid ligand (H4L = 4,4',4'',4'''-(1,4-phenylenebis(azanetriyl))tetrabenzoic acid) and ZrCl4 in the presence of trace water. It exhibits a three-dimensional porous structure. The BET surface area is 1112.72 m2/g and the average pore size distribution focus on 5.9, 8.0 and 9.3 Å. Interestingly, Zr-PTBA shows selective adsorption of SO2. The maximum uptake reaches 223.21 cm3/g at ambient condition. While it exhibits lower adsorption uptake of CO2 (30.50 cm3/g) and hardly adsorbs O2 (2.57 cm3/g) and N2 (1.31 cm3/g). Higher IAST selectivities of SO2/CO2 (21.9), SO2/N2 (912.7), SO2/O2 (2269.9) and SO2/CH4 (85.0) have been obtained, which reveal its' excellent gas separation performance. Breakthrough experiment further confirms its application for flue gas deep desulfurization both in dry and humid conditions. Furthermore, the gas adsorption results and mechanisms have also been studied by theoretical calculations.

Eriodictyol protects against Staphylococcus aureus-induced lung cell injury by inhibiting alpha-hemolysin expression.

Staphylococcus aureus (S. aureus) is a common pathogenic bacterium that causes various diseases in both humans and animals. With the increased prevalence of methicillin-resistant S. aureus, the therapeutic effects of commonly used antibiotics are limited against S. aureus infection. Novel treatment strategies and new antibiotics are needed urgently to address this concern. Many studies have shown that virulence factors secreted from S. aureus play vital roles in their pathogenic processes. Alpha-hemolysin (Hla), an important exotoxin in S. aureus, is one such virulence factor that increases sensitivity of multiple host cells to S. aureus resulting in various diseases. Eriodictyol is a flavonoid compound that exists in many fruits and vegetables. In this study, eriodictyol was demonstrated to inhibit the expression of Hla by hemolysis assays, western blotting, and RT-qPCR at the sub-minimal inhibitory concentration. In live/dead and cytotoxicity assays, the results showed that eriodictyol protected A549 cells against Hla-induced injury in a dose-dependent manner. The minimal inhibitory concentration of eriodictyol against S. aureus was 512 µg/mL. Eriodictyol can downregulate S. aureus Hla at both the expressional and transcriptional levels without affecting S. aureus growth. In addition, cell assays had proved that eriodictyol could protect A549 cells against Hla damage. Eriodictyol could therefore have the potential to treat S. aureus infection targeting Hla.

Sclareol Protects Staphylococcus aureus-Induced Lung Cell Injury via Inhibiting Alpha-Hemolysin Expression.

Staphylococcus aureus (S. aureus) is a common gram-positive bacterium that causes serious infections in humans and animals. With the continuous emergence of methicillin-resistant S. aureus (MRSA) strains, antibiotics have limited efficacy in treating MRSA infections. Accordingly, novel agents that act on new targets are desperately needed to combat these infections. S. aureus alpha-hemolysin plays an indispensable role in its pathogenicity. In this study, we demonstrate that sclareol, a fragrant chemical compound found in clary sage, can prominently decrease alpha-hemolysin secretion in S. aureus strain USA300 at sub-inhibitory concentrations. Hemolysis assays, western-blotting, and RT-PCR were used to detect the production of alpha-hemolysin in the culture supernatant. When USA300 was co-cultured with A549 epithelial cells, sclareol could protect the A549 cells at a final concentration of 8 µg/ml. The protective capability of sclareol against the USA300-mediated injury of A549 cells was further shown by cytotoxicity assays and live/dead analysis. In conclusion, sclareol was shown to inhibit the production of S. aureus alpha-hemolysin. Sclareol has potential for development as a new agent to treat S. aureus infections.

Steady-state BOLD Response to Higher-order Cognition Modulates Low-Frequency Neural Oscillations.

Steady-state responses (SSRs) reflect the synchronous neural oscillations evoked by noninvasive and consistently repeated stimuli at the fundamental or harmonic frequencies. The steady-state evoked potentials (SSEPs; the representative form of the SSRs) have been widely used in the cognitive and clinical neurosciences and brain-computer interface research. However, the steady-state evoked potentials have limitations in examining high-frequency neural oscillations and basic cognition. In addition, synchronous neural oscillations in the low frequency range (<1 Hz) and in higher-order cognition have received a little attention. Therefore, we examined the SSRs in the low frequency range using a new index, the steady-state BOLD responses (SSBRs) evoked by semantic stimuli. Our results revealed that the significant SSBRs were induced at the fundamental frequency of stimuli and the first harmonic in task-related regions, suggesting the enhanced variability of neural oscillations entrained by exogenous stimuli. The SSBRs were independent of neurovascular coupling and characterized by sensorimotor bias, an indication of regional-dependent neuroplasticity. Furthermore, the amplitude of SSBRs may predict behavioral performance and show the psychophysiological relevance. Our findings provide valuable insights into the understanding of the SSRs evoked by higher-order cognition and how the SSRs modulate low-frequency neural oscillations.

Identification of an intestine-specific promoter and inducible expression of bacterial α-galactosidase in mammalian cells by a lac operon system.

BACKGROUND: α-galactosidase has been widely used in animal husbandry to reduce anti-nutritional factors (such as α-galactoside) in feed. Intestine-specific and substrate inducible expression of α-galactosidase would be highly beneficial for transgenic animal production. METHODS: To achieve the intestine-specific and substrate inducible expression of α-galactosidase, we first identified intestine-specific promoters by comparing the transcriptional activity and tissue specificity of four intestine-specific promoters from human intestinal fatty acid binding protein, rat intestinal fatty acid binding protein, human mucin-2 and human lysozyme. We made two chimeric constructs combining the promoter and enhancer of human mucin-2, rat intestinal trefoil factor and human sucrase-isomaltase. Then a modified lac operon system was constructed to investigate the induction of α-galactosidase expression and enzyme activity by isopropyl ß-D-1-thiogalactopyranoside (IPTG) and an α-galactosidase substrate, α-lactose.We declared that the research carried out on human (Zhai Yafeng) was in compliance with the Helsinki Declaration, and experimental research on animals also followed internationally recognized guidelines. RESULTS: The activity of the human mucin-2 promoter was about 2 to 3 times higher than that of other intestine-specific promoters. In the lac operon system, the repressor significantly decreased (P < 0.05) luciferase activity by approximately 6.5-fold and reduced the percentage of cells expressing green fluorescent protein (GFP) by approximately 2-fold. In addition, the expression level of α-galactosidase mRNA was decreased by 6-fold and α-galactosidase activity was reduced by 8-fold. In line with our expectations, IPTG and α-lactose supplementation reversed (P < 0.05) the inhibition and produced a 5-fold increase of luciferase activity, an 11-fold enhancement in the percentage of cells with GFP expression and an increase in α-galactosidase mRNA abundance (by about 5-fold) and α-galactosidase activity (by about 7-fold). CONCLUSIONS: We have successfully constructed a high specificity inducible lac operon system in an intestine-derived cell line, which could be of great value for gene therapy applications and transgenic animal production.