Kontakti Srba i Habzburgovaca su otpočeli sredinom XV veka. U tom trenutku Habzburgovci su u liku Alberta Austrijskog prvi put seli na presto a Srbi su se borili za opstanak svoje srednjovekovne ...države. U kasnijem periodu karakter tih kontakata je bio drukčiji. Pojedinačni predstavnici Srba, feudalci prebegli na tlo Ugarske i nove vođe ratničkih družina povezivali su se sa Habzburgovcima nudeći im svoje vojničke usluge. Definitivan prelom nastaće u periodu posle Mohačke bitke kada se Habzburgovac Ferdinand I učvrstio na ugarskom prestolu. Time će otpočeti nov period veoma intenzivnih kontakata Srba sa Habzburgovcima koji će se najvećim delom odvijati na teritoriji razdrobljenog ugarskog kraljevstva koje se borilo za svoj opstanak.
Graphitic carbon nitride (g-C3N4) material with a similar structural phase to graphite opens new opportunities in energy conversion storage systems. The g-C3N4 sheets offered many defected sites that ...enhanced the adsorption and diffusion of electrolyte ions. High nitrogen concentration in g-C3N4 was ideal for increasing the binding energy between metals and carbon. The stability of pseudo-active metal oxides/chalcogenides supported by carbon results in improved capacitive performance. This study used a hydrothermal route to fabricate binary SrBi2O4/g-C3N4 composite onto g-C3N4 sheets. The SrBi2O4/g-C3N4 nanocomposite was characterized through various techniques including different analytical analyses. Among all evaluated electrodes for the electrochemical experiment binary composite SrBi2O4/g-C3N4 demonstrated the highest electrochemical activity and showed the capacitive of 777.2 F g−1 at 1 A g−1. Moreover, binary composite SrBi2O4/g-C3N4 was shown to have a lesser charge transfer resistance (Rct) of 0.87 Ω as compared to other bare fabricated materials. The exceptional electrochemical capability of SrBi2O4/g-C3N4 can be due to the combined effect of SrBi2O4 and g-C3N4 which included various redox state enhanced electrode wettability and superior structural and chemical stability. The composite material shows excellent power and high energy density of 319.95 W Kg−1 and 44.20 Wh Kg−1. Based on the findings our study suggested a practical approach to fabricated hybrid electrode materials that have optimum properties for use in energy storage devices in future supercapacitors.
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This research article is related to the piezocatalytic activity of SrBi4Ti4O15 (SBT) ferroelectric ceramic by using Methylene blue (MB) as a model dye. The piezocatalytic activity was further ...enhanced by poling of the ceramic catalyst powder. The ferroelectric ceramic was synthesized via a solid-state reaction route and calcinated at 950 °C. The synthesized ceramic was characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The process the poling enhanced the piezocatalytic activity by around 30%. A parametric study was also performed to get an insight into the influence of factors affecting activity.
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•The (2 0 0) facet of SrBi2Ta2O9 photocatalyst tends to accumulate electrons while (0 0 1) facet favors the accumulation of photogenerated holes.•High surface facet exposure of (2 0 0) plane in ...SrBi2Ta2O9 benifits photocatalytic NO removal.•Superoxide radicals play a vital role in photocatalytic NO removal by SrBi2Ta2O9.
Photocatalysts with exposure of different crystal facets often show great differences in their photocatalytic activities due to differences in surface atomic arrangement and coordination. Thus, the actual photoreaction mechanism of a specific crystal facet in photocatalysis deserves to be explored. In this paper, as a case study, SrBi2Ta2O9 photocatalyst with preferential facet exposure was explored for the photocatalytic removal of NO at a ppb level. The efficiency of NO removal was remarkably improved by tuning the crystal exposure facet with high (2 0 0) facet exposure ratio. Optimized exposure of (2 0 0) crystal facet in SrBi2Ta2O9 (SBT) by thermal calcination at 800 °C (SBT-800) leads to the highest NO removal activity of 51% under a 300 W Xe lamp for 20 min; under visible light, SBT 800 achieves a 5-fold enhancement in NO removal efficiency compared to its counterpart, SBT-900. Active species capture experiments prove that the superoxide radical ·O2− is the main active species for the photocatalytic removal of NO, and surface selective deposition experiments conclude that (2 0 0) is the main electron-rich crystal plane, based on which the results of density functional theory (DFT) computation reveal the BiO terminated nature of (0 0 1) crystal plane, where the models with both BiO and TaO terminated (0 0 1) planes were created and computated. Mechanistic study reveals that SrBi2Ta2O9 with a larger exposure of (2 0 0) facet provides more active reduction sites, thereby reducing more O2 to ·O2−, which further oxidizes the adsorbed NO to NO2−/NO3−. The present work underlines the role of facet tuning in the photoactivity modulation for NO removal photocatalytically.
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Formaldehyde (HCHO), as one of the main indoor toxic pollutions, presents a great threat to human health. Hence, it is imperative to efficiently remove HCHO and create a good indoor living ...environment for people. Herein, a layered perovskite material SrBi2Ta2O9 (SBT), was studied for the first time and exhibited superior photocatalytic efficiency and stability compared to commercial TiO2 (P25). Furthermore, a unique dark–light tandem catalytic mechanism was constructed. In the dark reaction stage, HCHO (Lewis base) site was adsorbed on the terminal (Bi2O2)2+ layer (Lewis acid) site of SBT in the form of Lewis acid-base complexation and was gradually oxidized to CO32− intermediate (HCHO → DOM (dioxymethylene) → HCOO− → CO32−). Then, in the light reaction stage, CO32− was completely converted into CO2 and H2O (CO32− → CO2). Our study contributes to a thorough comprehension of the photocatalytic oxidation of HCHO and points out its potential for day–night continuous work applications in a natural environment.
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Layered bismuth-based photocatalytic materials have great potential for environmental purification. In this work, we developed two novel layered bismuth-based borate photocatalysts ...CaBi2B2O7 (CBBO) and SrBi2B2O7 (SBBO) via solid-phase reaction. The crystal structure, microstructure and optical properties were investigated. The photocatalytic activities were studied by decomposition of tetracycline hydrochloride (TH) and evolution of reactive oxygen species (ROS) under UV light irradiation. The results revealed that CBBO and SBBO exhibit benign TH degradation activity with certain mineralization abilities. Within 4 min illumination, almost 70% and 58% of tetracycline hydrochloride was degraded by CBBO and SBBO, respectively. The quantitative capture experiment of radicals showed that the production rate of OH and O2− was determined to be 1.27 × 10-7 and 10.98 × 10-7 mol·L-1 min-1 for CBBO and 1.01 × 10-7 and 11.75 × 10-7 mol·L-1 min-1 for SBBO, respectively. Density functional theory (DFT) calculation results demonstrated that CBBO has smaller effective masses of electrons and holes than SBBO, which results in higher charge separation efficiency and photocatalytic activity. This work provides two new layered bismuth-based borate photocatalysts for photocatalytic environmental applications.
High-density lipoprotein (HDL) has traditionally been acknowledged as "good cholesterol" owing to its significant association with a decreased risk of atherosclerosis. This association is primarily ...attributed to HDL's direct involvement in cholesterol efflux capacity, which plays a pivotal role in reverse cholesterol transport. A novel active compound from Nannochloropsis microalgae termed lyso-DGTS, a lipid that contains EPA fatty acids, was previously isolated and found to increase paraoxonase 1 activity and enhance HDL-mediated cholesterol efflux and HDL-induced endothelial nitric oxide release. Here, the effect of different lyso-DGTS derivatives and analogs on HDL-mediated cholesterol efflux from macrophages was examined, and the mechanism was explored. Structure-activity relationships were established to characterize the essential lipid moieties responsible for HDL-mediated cholesterol efflux from macrophages. Lyso-DGTS, 1-carboxy-N-N-N-trimethyl-3-oleamidopropan-1-aminium, and lyso-platelet-activating factor increased HDL-mediated cholesterol efflux from macrophages dose-dependently, mainly via the ABCA1-mediated cholesterol efflux pathway. The effect of lyso-DGTS derivatives and analogs on the surface polarity of HDL was examined using the Laurdan generalized polarization (GP) assay. A reverse Pearson linear regression was obtained between Laurdan GP values and HDL-mediated cholesterol efflux. Because the incorporation of bioactive lipids into the surface phospholipid layer of HDL leads to a decrease in Laurdan GP, these bioactive lipids may induce lower phospholipid ordering and greater free space on the HDL particle surface, thereby enhancing apolipoprotein A1 binding to the ABCA1 receptor and improving ABCA1 cholesterol-mediated efflux. Our findings suggest a beneficial effect of lyso-DGTS and its bioactive lipid derivatives on increasing HDL-mediated cholesterol efflux activity from macrophages, which may impact atherosclerosis attenuation.
Bismuth layer-structured ferroelectric (BLSF) strontium bismuth titanate (SrBi4Ti4O15, SBT) ceramic oxides with B-site cobalt substitutions have been synthesized using conventional solid–state ...reaction. The dielectric, piezoelectric, and ferroelectric properties of cobalt-modified SBT are investigated in detail. The results indicate that cobalt is very effective in promoting the piezoelectric performance of SBT. The SBT modified with 3 mol% Co3+ (SBT-3Co) exhibits the optimized piezoelectric properties, with a piezoelectric constant d33 of 28 pC/N, which is the highest value among the modified SBT-based piezoelectric ceramics ever reported. The temperature-dependent electrical impedance, resonance frequencies, and electromechanical coupling factors (kp and kt) reveal that the cobalt-modified SBT ceramics have good thermal stabilities of electromechanical properties up to 300 °C. These results demonstrate that the cobalt-modified SBT ceramics are promising materials for high temperature piezoelectric sensors applications.
The manuscript deals with the thermal stabilities of piezoelectric properties of cobalt-modified SrBi4Ti4O15 (SBT) ceramics. The 3 mol% Co3+ modified SBT (SBT-3Co) ceramics exhibit a piezoelectric constant d33 of 28 pC/N and a Curie temperature Tc of 528 °C. The SBT-3Co ceramics have good thermal stabilities of electromechanical properties up to 300 °C. Display omitted
•A high level of piezoelectric performance (d33∼28 pC/N)is obtained.•High Curie temperature (Tc∼528 °C) is acquired for the optimal composition.•The SBT-3Co exhibits good thermal stabilities of electromechanical properties.•The Co-modified SrBi4Ti4O15 is promising as high temperature piezoelectric material.
Cholesteryl ester transfer protein (CETP) modulates lipoprotein metabolism by transferring cholesteryl ester (CE) and triglyceride (TG) between lipoproteins. However, differences in the way CETP ...functions exist across species. Unlike human CETP, hamster CETP prefers TG over CE as a substrate, raising questions regarding how substrate preference may impact lipoprotein metabolism. To understand how altering the CE versus TG substrate specificity of CETP might impact lipoprotein metabolism in humans, we modified CETP expression in fat/cholesterol-fed hamsters, which have a human-like lipoprotein profile. Hamsters received adenoviruses expressing no CETP, hamster CETP, or human CETP. Total plasma CETP mass increased up to 70% in the hamster and human CETP groups. Hamsters expressing human CETP exhibited decreased endogenous hamster CETP, resulting in an overall CE:TG preference of plasma CETP that was similar to that in humans. Hamster CETP overexpression had little impact on lipoproteins, whereas human CETP expression reduced HDL by 60% without affecting LDL. HDLs were TG enriched and CE depleted and much smaller, causing the HDL3:HDL2 ratio to increase threefold. HDL from hamsters expressing human CETP supported higher LCAT activity and greater cholesterol efflux. The fecal excretion of HDL-associated CE in human CETP animals was unchanged. However, much of this cholesterol accumulated in the liver and was associated with a 1.8-fold increase in hepatic cholesterol mass. Overall, these data show in a human-like lipoprotein model that modification of CETP's lipid substrate preference selectively alters HDL concentration and function. This provides a powerful tool for modulating HDL metabolism and impacting sterol balance in vivo.
The leading cause of morbidity and mortality is the result of cardiovascular disease, mainly atherosclerosis. The formation of macrophage foam cells by ingesting ox-LDL and focal retention in the ...subendothelial space are the hallmarks of the early atherosclerotic lesion. Lysophosphatidic acid (LPA), which is a low-molecular weight lysophospholipid enriched in oxidized LDL, exerts a range of effects on the cardiovascular system. Previous reports show that LPA increases the uptake of ox-LDL to promote the formation of foam cells. However, as the most active component of ox-LDL, there is no report showing whether LPA directly affects foam cell formation. The aim of this study was to investigate the effects of LPA on foam cell formation, as well as to elucidate the underlying mechanism. Oil red O staining and a Cholesterol/cholesteryl ester quantitation assay were used to evaluate foam cell formation in Raw264.7 macrophage cells. We utilized a Western blot and RT-PCR to investigate the relationship between LPA receptors and lipid transport related proteins. We found that LPA promoted foam cell formation, using 200 μM for 24 h. Meanwhile, the expression of the Scavenger receptor BI (SRBI), which promotes the efflux of free cholesterol, was decreased. Furthermore, the LPA1/3 receptor antagonist Ki16425 significantly abolished the LPA effects, indicating that LPA1/3 was involved in the foam cell formation and SRBI expression induced by LPA. Additionally, the LPA-induced foam cell formation was blocked with an AKT inhibitor. Our results suggest that LPA-enhanced foam cell formation is mediated by LPA1/3 -AKT activation and subsequent SRBI expression.
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•Lysophosphatidic acid individually induced the formation of foam cell.•Decrease expression of SRBI is responsible for the foam cell formation induced by LPA.•Activation of AKT is involved in the regulation of foam cell formation.
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