We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic ...evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t−5/3 decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ∼5 × 106 M black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy distribution is well described by a constant blackbody temperature of T ∼ 3 × 104 K over the monitoring period, with an observed peak luminosity of 1.1 × 1044 erg s−1. The optical spectra are characterized by a strong blue continuum and broad He ii and H lines, which are characteristic of TDEs. We compare the photometric and spectroscopic signatures of iPTF16axa with 11 TDE candidates in the literature with well-sampled optical light curves. Based on a single-temperature fit to the optical and near-UV photometry, most of these TDE candidates have peak luminosities confined between log(L erg s−1) = 43.4-44.4, with constant temperatures of a few ×104 K during their power-law declines, implying blackbody radii on the order of 10 times the tidal disruption radius, that decrease monotonically with time. For TDE candidates with hydrogen and helium emission, the high helium-to-hydrogen ratios suggest that the emission arises from high-density gas, where nebular arguments break down. We find no correlation between the peak luminosity and the black hole mass, contrary to the expectations for TDEs to have .
Potassium ion hybrid capacitors (KICs) have drawn tremendous attention for large-scale energy storage applications because of their high energy and power densities and the abundance of potassium ...sources. However, achieving KICs with high capacity and long lifespan remains challenging because the large size of potassium ions causes sluggish kinetics and fast structural pulverization of electrodes. Here, we report a composite anode of VO2–V2O5 nanoheterostructures captured by a 3D N-doped carbon network (VO2–V2O5/NC) that exhibits a reversible capacity of 252 mAh g–1 at 1 A g–1 over 1600 cycles and a rate performance with 108 mAh g–1 at 10 A g–1. Quantitative kinetics analyses demonstrate that such great rate capability and cyclability are enabled by the capacitive-dominated potassium storage mechanism in the interfacial engineered VO2–V2O5 nanoheterostructures. The further fabricated full KIC cell consisting of a VO2–V2O5/NC anode and an active carbon cathode delivers a high operating voltage window of 4.0 V and energy and power densities up to 154 Wh kg–1 and 10 000 W kg–1, respectively, surpassing most state-of-the-art KICs.
Acute Coronary Syndrome (ACS) and other heart emergency events require immediate chest pain identification in the ambulance. Specifically, early identification and triage is required so that patients ...with chest pain can be quickly sent to a hospital with appropriate care facilities for treatment. In the traditional approach, ambulance personnel often use symptom checklists to examine the patient and make a quick decision for the target hospital. However, not every hospital has specialist facilities to handle such emergency cases. If the result of the subsequent cardiac enzyme test performed at the target hospital strongly suggests the occurrence of myocardial infarction, the patient may need to be sent to another hospital with specialist facilities, such as Percutaneous Coronary Intervention. The standard procedure is time consuming, which may result in delayed treatment and reduce patent survival rate. To resolve this issue, we propose AMBtalk (Ambulance Talk) for accurate, early ACS identification in an ambulance. AMBtalk provides real-time connection to hospital resources, which reduces the elapsed time for treatment, and therefore, improves the patient survival rate. The key to success for AMBtalk is the development of the AllCheck
Internet of Things (IoT) device, which can accurately and quickly provide cardiovascular parameter values for early ACS identification. The interactions between the AllCheck
IoT device, the emergency medical service center, the ambulance personnel and the hospital are achieved through the AMBtalk IoT server in the cloud network. AllCheck
outperforms the existing cardiovascular IoT device solutions for ambulance applications. The testing results of the AllCheck
device show 99% correlation with the results of the hospital reports. Due to its excellent performance in quick ACS identification, the AllCheck
device was awarded the 17th Taiwan Innovators Award in 2020.
SN2017egm is the closest (z = 0.03) H-poor superluminous supernova (SLSN-I) detected to date, and a rare example of an SLSN-I in a massive, metal-rich galaxy. We present the HST UV and optical ...spectra covering 1000-5500 , taken at +3 day relative to the peak. Our data reveal two absorption systems at redshifts matching the host galaxy NGC 3191 (z = 0.0307) and its companion galaxy (z = 0.0299) 73″ apart. Weakly damped Ly absorption lines are detected at these two redshifts, with H i column densities of (3.0 0.8) × 1019 and (3.7 0.9) × 1019 cm−2, respectively. This is an order of magnitude smaller than the H i column densities in the disks of nearby galaxies (>1010 M ) and suggests that SN2017egm is on the near side of NGC 3191 and has a low host extinction (E(B − V) ∼ 0.007). Using unsaturated metal absorption lines, we find that the host of SN2017egm probably has a solar or higher metallicity and is unlikely to be a dwarf companion to NGC 3191. Comparison of early-time UV spectra of SN2017egm, Gaia16apd, iPTF13ajg, and PTF12dam finds that the continuum at λ > 2800 is well fit by a blackbody, whereas the continuum at λ < 2800 is considerably below the model. The degree of UV suppression varies from source to source, with the 1400-2800 continuum flux ratio of 1.5 for Gaia16apd and 0.4 for iPTF13ajg. This cannot be explained by the differences in magnetar power or blackbody temperature. Finally, the UV spectra reveal a common set of seven broad absorption features and their equivalent widths are similar (within a factor of 2) among the four events.
The synthesis and structural determination of a silver nanocluster Ag20{S2P(OiPr)2}12 (2), which contains an intrinsic chiral metallic core, is produced by reduction of one silver ion from the ...eight‐electron superatom complex Ag21{S2P(OiPr)2}12(PF6) (1) by borohydrides. Single‐crystal X‐ray analysis displays an Ag20 core of pseudo C3 symmetry comprising a silver‐centered Ag13 icosahedron capped by seven silver atoms. Its n‐propyl derivative, Ag20{S2P(OnPr)2}12 (3), can also be prepared by the treatment of silver(I) salts and dithiophosphates in a stoichiometric ratio in the presence of excess amount of BH4−. Crystal structure analyses reveal that the capping silver‐atom positions relative to their icosahedral core are distinctly different in 2 and 3 and generate isomeric, chiral Ag20 cores. Both Ag20 clusters display an emission maximum in the near IR region. DFT calculations are consistent with a description within the superatom model of an 8‐electron Ag135+ core protected by a Ag7{S2P(OR)2}125− external shell. Two additional structural variations are predicted by DFT, showing the potential for isomerism in such Ag20{S2P(OR)2}12 species.
Chiral silver nanocluster: The structure of an intrinsically chiral Ag20 nanocluster was determinded. Containing a silver‐centered icosahedron capped by seven silver atoms, it was rationalized to be an eight‐electron superatom complex. Isomeric Ag20 cores with distinct symmetry were characterized in two derivatives (nPr C1; iPr C3). DFT was used to predict the presence of additional structural variations to show rich isomerism in the Ag20 metallic core.
Although the modulation of Ca(2+) channel activity by extremely low-frequency electromagnetic fields (ELF-EMF) has been studied previously, few reports have addressed the effects of such fields on ...the activity of voltage-activated Na(+) channels (Na(v)). Here, we investigated the effects of ELF-EMF on Na(v) activity in rat cerebellar granule cells (GCs). Our results reveal that exposing cerebellar GCs to ELF-EMF for 10-60 min significantly increased Na(v) currents (I(Na)) by 30-125% in a time- and intensity-dependent manner. The Na(v) channel steady-state activation curve, but not the steady-state inactivation curve, was significantly shifted (by 5.2 mV) towards hyperpolarization by ELF-EMF stimulation. This phenomenon is similar to the effect of intracellular application of arachidonic acid (AA) and prostaglandin E(2) (PGE(2)) on I(Na) in cerebellar GCs. Increases in intracellular AA, PGE(2) and phosphorylated PKA levels in cerebellar GCs were observed following ELF-EMF exposure. Western blottings indicated that the Na(V) 1.2 protein on the cerebellar GCs membrane was increased, the total expression levels of Na(V) 1.2 protein were not affected after exposure to ELF-EMF. Cyclooxygenase inhibitors and PGE(2) receptor (EP) antagonists were able to eliminate this ELF-EMF-induced increase in phosphorylated PKA and I(Na). In addition, ELF-EMF exposure significantly enhanced the activity of PLA(2) in cerebellar GCs but did not affect COX-1 or COX-2 activity. Together, these data demonstrate for the first time that neuronal I(Na) is significantly increased by ELF-EMF exposure via a cPLA2 AA PGE(2) EP receptors PKA signaling pathway.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The glymphatic system is a recently discovered glial‐dependent macroscopic interstitial waste clearance system that promotes the efficient elimination of soluble proteins and metabolites from the ...central nervous system. Its anatomic foundation is the astrocytes and aquaporin‐4 (AQP4) water channels on the endfeet of astrocytes. The aim of this study is to evaluate the plasticity of the spinal glymphatic system in male SD rats with painful diabetic neuropathy (PDN) induced by type 2 diabetes mellitus. PDN rats were modeled under a high‐fat and high‐glucose diet with a low dose of streptozotocin. MRI was applied to observe the infiltration and clearance of contrast to indicate the functional variability of the glymphatic system at the spinal cord level. The paw withdrawal threshold was used to represent mechanical allodynia. The numerical change of glial fibrillary acidic protein (GFAP) positive astrocytes was assessed and the polarity reversal of AQP4 protein was measured by immunofluorescence. As a result, deceased contrast infiltration and clearance, enhanced mechanical allodynia, increased number of GFAP positive astrocytes, and reversed polarity of AQP4 protein were found in the PDN rats. The above molecular level changes may contribute to the impairment of the spinal glymphatic system in PDN rats. This study revealed the molecular and functional variations of the spinal glymphatic system in PDN rats and for the first time indicated that there might be a correlation between the impaired spinal glymphatic system and PDN rats.
The activity of spinal glymphatic system of rats with painful diabetic neuropathy was inhibited, and our results indicated that the increased number of GFAP positive astrocytes and aquaporin‐4 polarity reversal may worked as its mechanism.
Background/Aims: Chronic hepatitis B virus (HBV) infection markedly increases the risk of development of hepatocellular carcinoma (HCC). Among the seven viral proteins that HBV encodes, HBV X protein ...(HBx) appears to have the most oncogenic potential. The mitochondria-associated HBx can induce oxidative stress in hepatocytes, leading to the production of abundant reactive oxygen species (ROS). High levels of ROS usually induce oxidative DNA damage and 8-hydroxy-2-deoxyguanosine (8-OHdG), also known as 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG), which is one of the major products of DNA oxidation and an important biomarker for oxidative stress and carcinogenesis. Cells have evolved a mechanism to prevent oxidized nucleotides from their incorporation into DNA through nucleotide pool sanitization enzymes of MTH1 (NUDT1), MTH2 (NUDT15), MTH3 (NUDT18) and NUDT5. However, little is known as to whether HBx can regulate the expression of those enzymes and modulate the formation and accumulation of 8-oxodG in hepatocytes. Methods: The level of 8-oxodG was assessed by ELISA in stable HBV-producing hepatoma cell lines, an HBV infectious mouse model, HBV and HBx transgenic mice and HBV-infected patients versus their respective controls. Expression of MTH1, MTH2, MTH3 and NUDT5 was determined by a real-time quantitative PCR and western blot analysis. Transcriptional regulation of MTH1 and MTH2 expression by HBx and the effect of HBx on MTH1 and MTH2 promoter hypermethylation were examined using a luciferase reporter assay and bisulfite sequencing analysis. Results: In comparison with controls, significantly higher levels of 8-oxodG were detected in the genome and culture supernatant of stable HBV-producing HepG2.2.15 cells, in the sera and liver tissues of HBV infectious mice and HBV or HBx transgenic mice, and in the sera of HBV-infected patients. Expression of HBx in hepatocytes significantly increased 8-oxodG level and reduced the expression of MTH1 and MTH2 at both mRNA and protein levels. It was also demonstrated that HBx markedly attenuated the MTH1 or MTH2 promoter activities through hypermethylation. Furthermore, enhancement of 8-oxodG production by HBx was reversible by overexpression of MTH1 and MTH2. Conclusion: Our data show that HBx expression results in the accumulation of 8-oxodG in hepatocytes through inhibiting the expression of MTH1 and MTH2. This may implicate that HBx may act as a tumor promoter through facilitating the mutational potential of 8-oxodG thus connecting a possible link between HBV infection and liver carcinogenesis.
Sepsis-induced myocardial dysfunction (SIMD) is one of the serious health-affecting problems worldwide. At present, the mechanisms of SIMD are still not clearly elucidated. The NOD-like receptor ...protein 3 (NLRP3) inflammasome has been assumed to be involved in the pathophysiology of SIMD by regulating multiple biological processes. NLRP3 inflammasome and its related signaling pathways might affect the regulation of inflammation, autophagy, apoptosis, and pyroptosis in SIMD. A few molecular specific inhibitors of NLRP3 inflammasome (e.g., Melatonin, Ulinastatin, Irisin, Nifuroxazide, and Ginsenoside Rg1, etc.) have been developed, which showed a promising anti-inflammatory effect in a cellular or animal model of SIMD. These experimental findings indicated that NLRP3 inflammasome could be a promising therapeutic target for SIMD treatment. However, the clinical translation of NLRP3 inhibitors for treating SIMD still requires robust in vivo and preclinical trials.
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•NLRP3 inflammasome, a pivotal mediator in the activation of the innate immune system in response to infection, has been found to play a key role in the pathophysiology of SIMD.•NLRP3 contributes to the development of SIMD by regulating its targeted genes and signal cascades, which function together on inflammation, autophagy, apoptosis, and pyroptosis.•NLRP3 inflammasome inhibitor exert potential anti-inflammatory effects in SIMD, indicating it may be a potential therapeutic target or preventive agent for SIMD treatment in clinical practice.
Lectin-like oxidized low-density lipoprotein-1 (LOX-1) is the major receptor for oxidized low density lipoprotein (ox-LDL) uptake in human umbilical vein endothelial cells (HUVECs). Previously, we ...found that rapamycin inhibited ox-LDL accumulation in HUVECs, and this effect was related to its role in increasing the activity of autophagy-lysosome pathway. In this study, we determined whether rapamycin could also reduce ox-LDL uptake in HUVECs and investigated the underlying signaling mechanisms.
Flow cytometry and live cell imaging showed that rapamycin reduced Dil-ox-LDL accumulation in HUVECs. Furthermore, rapamycin reduced the ox-LDL-induced increase in LOX-1 mRNA and protein levels. Western blotting showed that rapamycin inhibited mechanistic target of rapamycin (mTOR), p70s6k and IκBα phosphorylation triggered by ox-LDL. Flow cytometry implied that mTOR, NF-κB knockdown and NF-κB inhibitors significantly reduced Dil-ox-LDL uptake. Moreover, immunofluorescent staining showed that rapamycin reduced the accumulation of p65 in the nucleus after ox-LDL treatment for 30 h. mTOR knockdown decreased LOX-1 protein production and IκBα phosphorylation induced by ox-LDL. NF-κB knockdown and NF-κB inhibitors reduced LOX-1 protein production, but did not inhibit mTOR phosphorylation stimulated by ox-LDL.
These findings demonstrate that rapamycin reduce mTOR phosphorylation and subsequently inhibit NF-κB activation and suppresses LOX-1, resulting in a reduction in ox-LDL uptake in HUVECs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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![[Ag20{S2P(OR)2}12]: A Super...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0947-6539/small "[Ag20{S2P(OR)2}12]: A Superatom Complex with a Chiral Metallic Core and High Potential for Isomerism")
