The workability and ductility of metals usually degrade with exposure to irradiation, hence the phrase “radiation damage”. Here, we found that helium (He) radiation can actually enhance the ...room-temperature deformability of submicron-sized copper. In particular, Cu single crystals with diameter of 100–300 nm and containing numerous pressurized sub-10 nm He bubbles become stronger, more stable in plastic flow and ductile in tension, compared to fully dense samples of the same dimensions that tend to display plastic instability (strain bursts). The sub-10 nm He bubbles are seen to be dislocation sources as well as shearable obstacles, which promote dislocation storage and reduce dislocation mean free path, thus contributing to more homogeneous and stable plasticity. Failure happens abruptly only after significant bubble coalescence. The current findings can be explained in light of Weibull statistics of failure and the beneficial effects of bubbles on plasticity. These results shed light on plasticity and damage developments in metals and could open new avenues for making mechanically robust nano- and microstructures by ion beam processing and He bubble engineering.
Adverse maternal outcomes and perinatal complications are closely associated with overt maternal hypothyroidism, but whether these complications occur in women with subclinical hypothyroidism (SCH) ...during pregnancy remains controversial. The aim of this study was to evaluate the effects of SCH on maternal and perinatal outcomes during pregnancy.
A prospective study of data from 8012 pregnant women (371 women with SCH, 7641 euthyroid women) was performed. Maternal serum samples were collected in different trimesters to examine thyroid hormone concentrations. SCH was defined as a thyroid stimulating hormone concentration exceeding the trimester-specific reference value with a normal free thyroxine concentration. The occurrence of maternal outcomes, including gestational hypertension (GH), gestational diabetes mellitus, placenta previa, placental abruption, prelabor rupture of membranes (PROM), and premature delivery; and perinatal outcomes, including intrauterine growth restriction (IUGR), fetal distress, low birth weight (LBW; live birth weight ≤ 2500 g), stillbirth, and malformation, was recorded. Logistic regression with adjustment for confounding demographic and medical factors was used to determine the risks of adverse outcomes in patients with SCH.
Compared with euthyroid status, SCH was associated with higher rates of GH (1.819% vs. 3.504%, P = 0.020; χ2 = 7.345; odds ratio (OR), 2.243; 95% confidence interval (CI), 1.251-4.024), PROM (4.973% vs. 8.625%, P = 0.002; χ2 = 72.102; adjusted OR, 6.014; 95% CI, 3.975-9.099), IUGR (1.008% vs. 2.965%, <0.001; χ2 = 13.272; adjusted OR, 3.336; 95% CI, 1.745-6.377), and LBW (1.885% vs. 4.582%, P<0.001; χ2 = 13.558; adjusted OR, 2.919; 95% CI, 1.650-5.163).
The results of this study indicate that pregnant women with SCH had increased risks of GH and PROM, and their fetuses and infants had increased risks of IUGR and LBW. Thus, routine maternal thyroid function testing is necessary to improve maternal and perinatal outcomes.
The energy storage density of a Ba0.4Sr0.6TiO3 ceramic with the addition of 5–20 vol% glass was investigated. The results show that the improvement of the energy density in glass‐added Ba0.4Sr0.6TiO3 ...samples arises due to two factors: one is that the breakdown strength is notably improved due to the decrease of the porosity and the reduction of the grain size and pore size in glass‐added samples and the other is that the remnant polarization of glass‐added samples is decreased. The energy density of the samples containing 5 vol% glass additive was improved by a factor of 2.4 compared with that of pure Ba0.4Sr0.6TiO3.
Sulfur dioxide (SO2) is a common air pollutant and is detrimental to many organs. Its toxic effects including oxidative damage, deoxyribonucleic acid (DNA) damage and inflammation have been ...extensively studied. However, recent studies showed that SO2 can be generated endogenously in mammals. In contrast to the toxic effects of SO2, protective effects have also been found in mammals. Endogenous SO2 has antioxidant, anti-inflammatory, anti-hypertension, and anti-atherogenic effects and regulates vascular tone and cardiac function in mammals. SO2 may have a dual role in regulating physiological and pathophysiological effects in mammals. The biological effects of SO2 in mammals are reviewed in this study.
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The formation of local chemical order in medium-entropy alloys and high-entropy alloys (MEAs/HEAs) has been strongly suggested in recent experimental observations. Since chemical ...order can lead to changes in mechanical and functional properties, tailoring of chemical order is a promising approach for further improving those properties of MEAs and HEAs. However, details remain unclear regarding the atomic structure of the chemical order and the formation kinetics. Here, employing a large-scale Monte Carlo/molecular dynamics hybrid annealing simulation with a neural network potential, we find a chemical-domain structure (CDS) after annealing below 800 K in FCC CrCoNi MEA. In addition, the formation kinetics, such as the formation time and process and time–temperature–chemical-order diagrams of the CDS, were successfully obtained using a kinetic Monte Carlo simulation with artificial neural network acceleration. The findings provide key information for controlling chemical order via thermal processing.
In the face of deeply exploring and exploiting marine resources, the Internet of Underwater Things (IoUT) networks have drawn great attention considering its widely distributed low-cost and ...easy-deployment smart sensing nodes. However, given the hostile underwater environment, it is critical to conceive energy-efficient information collection because of limited underwater energy supply and inefficient artificial recharge methods. Characterized by high flexibility and maneuverability, autonomous underwater vehicles (AUVs) are regarded as a promising solution for information collection in the IoUT relying upon delicate AUVs' trajectory and information collection strategy design with the spirit of balancing their energy consumption and information processing capability. In this article, we propose a heterogeneous AUV-aided information collection system with the aim of maximizing the energy efficiency of IoUT nodes taking into account AUV trajectory, resource allocation, and the Age of Information (AoI). Moreover, based on the particle swarm optimization (PSO), we obtain the trajectory of AUVs with low time complexity. Additionally, a two-stage joint optimization algorithm based on the Lyapunov optimization is constructed to strike a tradeoff between energy efficiency and system queue backlog iteratively. Finally, simulation results validate the effectiveness and superiority of our proposed strategy.
Aim
Dilated cardiomyopathy (DCM) is characterised by left ventricular dilation and associated with systolic dysfunction. Recent evidence has reported the high expression of latent transforming growth ...factor beta binding protein 2 (LTBP2) in heart diseases, which may play a role in regulating multiple biological functions of myocardial cells. Thus, this study set out to investigate the molecular mechanism and effects of LTBP2 in myocardial oxidative stress injury, fibrosis and remodelling in a rat model of DCM, with the involvement of NF‐κB signalling pathway.
Methods
The rat model of DCM was treated with si‐LTBP2 and/or activator of NF‐κB signalling pathway to examine the haemodynamic indexes, cardiac functions, oxidative stress injury, fibrosis and remodelling. Moreover, in vitro experiments were conducted to verify the regulatory role of LTBP2 and NF‐κB signalling pathway in DCM.
Results
LTBP2 was up‐regulated in DCM rats. After LTBP2 was knocked down, haemodynamic indexes, HW/BW ratio, collagen volume fraction (CVF) level, positive expression of LTBP2, levels of reactive oxygen species (ROS), malondialdehyde (MDA), interleukin‐6 (IL‐6), tumour necrosis factor‐alpha (TNF‐α), tumour necrosis factor beta 1 (TGF‐β1) and brain natriuretic peptide (BNP) were all decreased. Meanwhile, levels of LTBP2, Col‐I, Col‐III, p65 and p52 were also reduced, while HW, BW and levels of SOD and TAOC were increased. In contrast, activation of NF‐κB signalling pathway reversed effects of LTBP2 gene silencing. These findings were confirmed by in vivo experiments.
Conclusions
LTBP2 silencing can attenuate myocardial oxidative stress injury, myocardial fibrosis and myocardial remodelling in DCM rats by down‐regulating the NF‐κB signalling pathway.
Na 2 O-PbO-Nb 2 O 5 - SiO 2 glass-ceramic dielectrics and internal electrode structures were investigated to improve the general energy storage density of capacitors. This work was brought out by the ...motivation of elimination of structural flaws and pores remaining in dielectrics and at electrode/dielectric interfaces, which are the main causes of low dielectric strength and low energy storage density of the traditional sintered dielectric capacitors. The combination of pore-free glass-ceramic dielectrics and series internal electrodes was adapted in the design of high energy storage density capacitors (HESDCs). The results show that the dielectric properties and the breakdown strength of glass-ceramics could be optimized through appropriate crystallization profiles, which could lead to an energy storage density of up to 17 J/cm 3 for glass-ceramics crystallized at 850degC for 3 h. The series multilayer capacitors could bear a rather higher electric field compared with the traditional ones without internal electrodes, and the dielectric strength could be further improved when the internal electrodes are made of sputtered gold films and printed paste. As a result, an overall energy storage density of about 8 J/cm 3 has been achieved for the capacitor with internal electrodes made of gold film and screen-printed paste when the 850degC-crystallized glass-ceramic dielectric was used.
On 31 July 2020, the Beidou global navigation satellite system (BDS-3) was officially announced as being commissioned. In addition to offering global positioning, navigation, and timing (PNT) ...services, BDS-3 also provides precise point positioning (PPP) augmentation services. The satellite orbit correction, clock correction and code bias correction of BDS-3 and other global navigation satellite systems (GNSS) are broadcast by the BDS-3 geostationary earth orbit (GEO) satellites through the PPP-B2b signal. The PPP-B2b service is available for users in China and the surrounding area. In this study, an initial assessment of the PPP-B2b service is presented, with collected 3-day PPP-B2b messages. Based on broadcast ephemeris and PPP-B2b messages, the precise satellite orbits and clock offsets can be recovered. This precision is evaluated with the precise ephemeris from the GeoForschungsZentrum Potsdam (GFZ) analysis center as references. The results indicate that the accuracy of BDS-3 satellite orbits in the direction of radial, along-track, and cross-track is 0.138, 0.131, and 0.145 m, respectively, and for GPS a corresponding accuracy of 0.104, 0.160, and 0.134 m, respectively, could be obtained. The precision of clock offsets can reach a level of several centimeters for both GPS and BDS-3. Both the performance of static PPP and kinematic PPP are evaluated using the observations from four international GNSS monitoring assessment service (iGMAS) stations. Regarding static PPP, the average convergence time is 17.7 min to achieve a horizontal positioning accuracy of better than 0.3 m, and a vertical positioning accuracy of better than 0.6 m. The average positioning accuracy in the direction of east, north, and up-directions are 2.4, 1.6, and 2.3 cm. As to kinematic PPP, the average RMS values of positioning errors in the direction of east, north, and up are 8.1 cm, 3.6 cm, and 8.0 cm after full convergence.
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