In this paper, graphene oxide (GO) and maleic anhydride–functionalized pristine graphene (MAGN) based on Diels-Alder reaction were synthesized in order to comparatively study the reinforcement effect ...on the polyethylene terephthalate (PET) composites. PET nanocomposites with GO or MAGN were prepared by a melt-blending method with varying concentrations of nanofillers from 0.05 wt to 0.3 wt%. The structure, the thermal stability, and the mechanical and crystallization properties of the obtained PET composites were systematically investigated by scanning electronic microscopy (SEM), tensile tests, thermo-gravimetric analysis (TGA), differential scanning Calorimetry (DSC), and dynamic mechanical analysis (DMA). The results show that the thermal stability and the mechanical and crystallization properties of EPT are improved by GO and MAGN inclusion. When the filler loading was 0.1 wt%, the tensile strength of MAGN/PET and GO/PET was increased by 28.9 % and 11.8% compared with the pure PET, which indicates the MAGN shows a better reinforcement effect on PET nanocomposites. Moreover, the MAGN also acts as a more efficient nucleating agent for PET compared with GO exhibiting higher degrees of crystallinity.
Abstract
The X-ray pulsar 1A 0535+262 exhibited a giant outburst in 2020, offering us a unique opportunity for X-ray polarimetry of an accreting pulsar in the supercritical state. Measurement with ...PolarLight yielded a nondetection in 3–8 keV; the 99% upper limit of the polarization fraction (PF) is found to be 0.34 averaged over spin phases, or 0.51 based on the rotating vector model. No useful constraint can be placed with phase-resolved polarimetry. These upper limits are lower than a previous theoretical prediction of 0.6–0.8, but consistent with those found in other accreting pulsars, like Her X-1, Cen X-3, 4U 1626−67, and GRO J1008−57, which were in the subcritical state, or at least not confidently in the supercritical state, during the polarization measurements. Our results suggest that the relatively low PF seen in accreting pulsars cannot be attributed to the source not being in the supercritical state, but could be a general feature.
We propose a future mission concept, the MeV Astrophysical Spectroscopic Surveyor (MASS), which is a large area Compton telescope using 3D position sensitive cadmium zinc telluride (CZT) detectors ...optimized for emission line detection. The payload consists of two layers of CZT detectors in a misaligned chessboard layout, with a total geometric area of 4096 cm
2
for on-axis observations. The detectors can be operated at room-temperature with an energy resolution of 0.6% at 0.662 MeV. The in-orbit background is estimated with a mass model. At energies around 1 MeV, a line sensitivity of about
10
-
5
photons cm
-
2
s
-
1
can be obtained with a 1 Ms observation. The main science objectives of MASS include nucleosynthesis in astrophysics and high energy astrophysics related to compact objects and transient sources. The payload CZT detectors weigh roughly 40 kg, suggesting that it can be integrated into a micro- or mini-satellite. We have constructed a pathfinder, named as MASS-Cube, to have a direct test of the technique with 4 detector units in space in the near future.
Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is essential for biosynthetic reactions and antioxidant functions; however, detection of NADPH metabolism in living cells remains ...technically challenging. We develop and characterize ratiometric, pH-resistant, genetically encoded fluorescent indicators for NADPH (iNap sensors) with various affinities and wide dynamic range. iNap sensors enabled quantification of cytosolic and mitochondrial NADPH pools that are controlled by cytosolic NAD
kinase levels and revealed cellular NADPH dynamics under oxidative stress depending on glucose availability. We found that mammalian cells have a strong tendency to maintain physiological NADPH homeostasis, which is regulated by glucose-6-phosphate dehydrogenase and AMP kinase. Moreover, using the iNap sensors we monitor NADPH fluctuations during the activation of macrophage cells or wound response in vivo. These data demonstrate that the iNap sensors will be valuable tools for monitoring NADPH dynamics in live cells and gaining new insights into cell metabolism.
The launched hepatitis B vaccine could induce powerful antibodies, whereas it failed to improve potent cellular immune responses due to that the Th2-type response-induced aluminum adjuvant was ...adopted. Here, to target antigen-presenting cells under the epidermis and induce potent cellular and humoral immune responses, mannose-modified poly
d
,
l
-lactide-co-glycolic acid (PLGA) was synthesized and nanoparticle (MNP)-loaded hepatitis B surface antigen (HBsAg) protein was prepared. HBsAg could be slowly released and highly presented to lymphocytes which facilitated to produce long-lasting immunity based on characters of PLGA.
In vitro
uptake test results showed that MNPs could enhance internalization in bone marrow–derived dendritic cells (BMDCs) and RAW 264.7 cells. Subcutaneous delivery of MNPs into mice kept humoral immune and strengthened cellular immune responses. Experimental results indicated that MNPs showed significantly modified properties compared with parental PLGA nanoparticles. Thus, the obtained MNPs could be a promising vehicle for hepatitis B vaccine delivery.
VSMC proliferation and ECM deposition always resulted in intimal hyperplasia. Astragalus–Angelica combination has a protective effect on the cardiovascular system. The inhibition effect of different ...Astragalus–Angelica combination on the hyperplastic intima after vascular balloon injury in rats was investigated in this study. Astragalus–Angelica combination can inhibit the intima hyperplasia after balloon injury, in which a 1:1 ratio shows excellent results. Astragalus–Angelica combination can enhance the expression of smooth muscle α-actin (SMа-actin) and inhibit the expression of proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin E, collagen I (Col-I), fibronectin (FN), and matrix metallopeptidase-9 (MMP-9) in hyperplastic intima, suggesting that Astragalus–Angelica combination can inhibit the intimal hyperplasia of blood vessels in rats. The mechanism is related to the inhibition of PI3K/Akt signaling pathway activation and thereby inhibits the phenotypic transformation and cell proliferation of VSMCs and thus inhibits the extracellular matrix (ECM) deposition of vascular wall during intimal hyperplasia.
Abstract
We report the detection of X-ray polarization in the neutron-star low-mass X-ray binary Scorpius (Sco) X-1 with PolarLight. The result is energy-dependent, with a nondetection in 3–4 keV but ...a 4
σ
detection in 4–8 keV; it is also flux-dependent in the 4–8 keV band, with a nondetection when the source displays low fluxes but a 5
σ
detection during high fluxes, in which case we obtain a polarization fraction of 0.043 ± 0.008 and a polarization angle of 52.°6 ± 5.°4. This confirms a previous marginal detection with OSO-8 in the 1970s and marks Sco X-1 as the second astrophysical source with a significant polarization measurement in the keV band. The measured polarization angle is in line with the jet orientation of the source on the sky plane (54°), which is supposedly the symmetry axis of the system. Combining previous spectral analysis, our measurements suggest that an optically thin corona is located in the transition layer under the highest accretion rates, and disfavor the extended accretion disk corona model.
The objective of this study is to develop a new hepatitis B surface antigen (HBsAg) delivery system by coating soluble microneedle arrays with mannose-modified PLGA nanoparticles (MNPs). MNPs of ...different sizes were synthesized. The effects these nanoparticles on the maturation of dendritic cells were studied by flow cytometry. HBsAg-containing MNPs (HBsAg/MNPs) of the appropriate sizes were coated into water-soluble microneedle arrays. The
in vitro
characteristics of microneedles arrays and the immune responses after subcutaneous administration in mice were studied. The results showed that PLGA nanoparticles with an average size of about 800 nm showed the most significant effects in stimulating the maturation of dendritic cells. In the water-soluble microneedle array, the targeted PLGA nanoparticles containing HBsAg were distributed discretely with a maximum distribution height of about 280 μm with a drug load of 0.98 ± 0.05 μg/mg. The drug-containing microneedle arrays exhibited excellent mechanical properties and improved biosafety. The results of immune responses
in vivo
showed that the subcutaneous administration of the microneedle arrays induced the proliferation of splenocyte, secreted specific IL-12 and IFN-γ, and promote the production of IgG in mice. This study verifies the feasibility of soluble composited microneedles administration in hepatitis B immunization, and provides new ideas for the development and application of non-injectable vaccine delivery systems.
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