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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The structural characteristics and microwave dielectric properties of SrBi
2
TeO
7
ceramics intended for low-temperature co-fired ceramic (LTCC) applications were investigated. Comprehensive analyses ...were conducted using x-ray diffraction, structural refinement, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. The findings demonstrated that SrBi
2
TeO
7
ceramics possess a pure cubic structure. Scanning electron microscopy characterizes the grain microstructure, revealing a relative density of 95.5% for SrBi
2
TeO
7
ceramic. Optimal microwave dielectric properties were achieved for SrBi
2
TeO
7
ceramics calcined at 765°C, displaying a relative permittivity (
ε
r
) of 24.96, a
Q
×
f
value of 25,898 GHz (
f
= 6.6 GHz), and a temperature coefficient of resonant frequency (
τ
f
) of –80.7 ppm/°C. The combination of low sintering temperature and minimal dielectric loss renders these ceramics advantageous for utilization in LTCC materials.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An appropriate amount of Zn-ions are incorporated into the high Curie temperature bismuth layer-structure ferroelectric material to fabricate Sr0.2Na0.4Pr0.4Bi4Ti4O15:xwt%ZnO; (SNPBT:xZn), with x = ...0, 0.10, 0.15, and 0.20 ceramic series to investigate the magnetic, ferroelectric, and energy storage efficiency and piezoelectric properties. Pure SNPBT and SNPBT:xZn ceramics have maintained their structure even after the intercalation of Zn-ions at the lattice sites of SNPBT. The addition of ZnO in SNPBT has improved the multifunctional properties of the material at x = 0.15. At room temperature, SNPBT:0.15Zn has shown a high relative density of 96%, exhibited weak ferromagnetic behavior along with a low saturation magnetization (Ms) of 0.028 emu/g with a low coercive field of 306 Oe, a high remnant polarization (Pr) of 9.04 µC/cm2, a recoverable energy density (Wrec) of ~0.5 J/cm3, an energy conversion efficiency (η) of ~41%, a high piezoelectric co-efficient (d33) of 21 pC/N, and an impedance of 1.98 × 107 Ω, which are much improved as compared to pure SBT or pure SNPBT ceramics. Dielectric Constant (ɛr) versus temperature plots present the sharp peak for SNPBT:0.15Zn ceramic at a Curie temperature (TC) ~ 605 °C, confirming the strong ferroelectric nature of the ceramic. Moreover, SNPBT:0.15Zn ceramic has shown strong, piezoelectric, thermally stable behavior, which remains at 76% (16 pC/N) of its initial value even after annealing at 500 °C. The achieved results clearly indicate that SNPBT:0.15Zn ceramic is a promising candidate for future wide-temperature pulse power applications and high-temperature piezoelectric devices.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
SrBi
4
Ti
4
O
15
is a four-layer member of the Aurivillius compound and reported to have photocatalyst properties with a band gap energy of 3.0 eV (420 nm). Doped with metal elements is a strategy to ...reduce the band gap energy of photocatalyst material in order to increase its utilization under a wider energy spectrum of visible light. Here in, Fe-doped SrBi
4
Ti
4
O
15
was synthesized using Na
2
SO
4
/K
2
SO
4
molten salt method. The diffractogram revealed that all samples were successfully synthesized in the
A
2
1
am
space group with no impurity phase. Raman spectra confirmed the existence of a typical Raman vibration peak for a four-layer Aurivillius family compound and the local changes in TiO
6
structure due to Fe dopant mirrored by vibration mode at ~ 559 cm
−1
. SEM images showed that the all samples morphology is plate-like however, the particle size of Fe-doped SrBi
4
Ti
4
O
15
is bigger than the undoped compound. Meanwhile, the UV–Vis DRS spectra revealed that Fe dopant could effectively reduce the band gap energy resulting in obvious red shift absorption to the wider visible light region (530–705 nm).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
For the proposed work, the electrical properties of metal–ferroelectric–insulator–silicon (MFeIS) capacitors with Sr
0.8
Bi
2.2
Ta
2
O
9
(SBT) ferroelectric film deposited on HfO
2
/Si substrate have ...been investigated. The SBT film was deposited by RF sputtering and HfO
2
film by plasma-enhanced atomic layer deposition (PEALD). The structural characteristic of the deposited ferroelectric and dielectric films was obtained using X-ray diffraction and multiple angle ellipsometric analysis. XRD results indicate the polycrystalline and perovskite structure of the SBT film and amorphous structure of the HfO
2
film annealed at different temperatures. SBT film deposited on the silicon substrate and annealed at 500 °C shows the maximum refractive index of 3.46 with the maximum grain size of 32 nm. Metal/ferroelectric/silicon (MFeS), metal/ferroelectric/metal (MFeM), metal/insulator/silicon (MIS) and metal/ferroelectric/insulator/silicon (MFeIS) structures were fabricated to obtain the electrical and ferroelectric properties. MFeIS structure with 10 nm buffer layer shows the improved memory window of 5 V as compared to the 3.07 V in the MFeS structures. MFeI
(10 nm)
S structure even shows endurance higher than 10
12
read/write cycles and data retention for more than 8 h.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Co-precipitation-hydrothermal synthesized of SrBi2Nb2O9 was described.•Structural characterization was reported.•Dielectric properties at room temperature of proposed material can match them up with ...SrBi2Nb2O9 prepared via solid state reaction method.
Strontium Bismuth Niobate (SrBi2Nb2O9) was synthesized by co-precipitation-hydrothermal method. Precipitation step was first carried out at room temperature at which the powder was prepared from aqueous solution of Bi(NO3)3, Sr(NO3)2 and Nb2O5. Then the process is completed by hydrothermal treatment. The compound crystallized in the orthorhombic structure. The characteristic bands, at approximately 619cm−1 and 816cm−1 were observed. The grain size is around 1µm. The dielectric properties at room temperature show low loss values at higher frequencies which makes it suitable for ferroelectric random access memory applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We demonstrated the formation and reading of flexoelectrically-switched polarization nanobits in c-oriented, epitaxial layered-perovskite thin films. Highly c-oriented epitaxial SrBi2Nb2O9 (SBN) thin ...films were deposited on Nb-doped single crystal (100) SrTiO3 (Nb:STO) substrates via pulsed laser deposition (PLD) technology. X-ray diffraction (XRD) experiments, ferroelectric hysteresis loops, leakage current curves, and fatigue characteristics revealed that these films preferred in-plane oriented domains. Flexoelectrically switched polarization nanobits with horizontally switched domains were formed within an upwardly switched domain of the c-oriented epitaxial SBN thin film by applying external forces orthogonal to the surface. In particular, flexoelectrically switched polarization nanobits didn't have out-of-plane-oriented domains, reflecting the c-oriented nature of the Aurivillius SBN thin film.
•Switched ferroelectric polarization nanobits by flexoelectric force.•Highly c-oriented Aurivillius SBN thin films.•Crystallinity-dependent switching characteristics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
The present work investigates microstructural, structural, ferroelectric and dielectric properties of Holmium, Ho
3+
, doped SrBi
4
Ti
4
O
15
(SBT). Polycrystalline ceramics (SrBi
4-x
Ho
x
Ti
4
O
15
...SBHT, where x = 0, 0.02. and 0.03) were prepared by solid-state reaction method using high energy planetary ball mill. The surface morphology of all samples displayed dense microstructure and average grain size decreased with Holmium content increase. The XRD results of samples confirmed a single phase of SBT with orthorhombic crystal structure and a reduction in unit cell volume with the substitution of Holmium at B-site. The improvement in the structural and microstructural properties greatly enhanced the electric properties of SBHT. SBHT (x = 0.02) sample showed the improved ferroelectric properties (remnant polarization P
r
= 1.63 μC/cm
2
and Coercive field E
c
= 0.51 kV/cm) making them suitable for ferroelectric applications. High Curie temperature (T
C
= 626 °C), elevated dielectric constant (ε
r
= 236) and low loss (tanδ = 0.062) are obtained with the substitution of Ho (for x = 0.03) at B- site of SBT. These ceramics have high T
C
and improved thermal stability which makes these apt for the applications in high temperature sensors.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
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