Abstract
Diffuse
γ
-ray emission between 10 and 1000 TeV from the Galactic plane was recently measured by the Large High Altitude Air Shower Observatory (LHAASO). These observations will help ...tremendously in constraining the propagation and interaction of cosmic rays in the Milky Way. Additionally, new measurements of cosmic-ray spectra reach a very high precision of up to 100 TeV energies, revealing multiple spectral structures of various species. In this work, based on up-to-date measurements of local cosmic-ray spectra and a simplified propagation setup, we confront a model prediction of diffuse
γ
-ray emission with measurements of diffuse
γ
-rays. To better constrain the low-energy part of the model, we analyze the 14.6 yr of Fermi Large Area Telescope (Fermi-LAT) data to extract the Galactic diffuse emission between 1 and 500 GeV from the same sky regions of LHAASO, after subtracting the contribution from known sources and the isotropic diffuse
γ
-ray background. The joint Fermi-LAT and LHAASO spectra thus cover a very wide energy range from 1 GeV to 1 PeV with small gaps from 0.5 to 10 TeV. Compared with the prediction, we find that clear excesses between several GeV and ∼60 TeV of the diffuse emission exist. Possible reasons to explain the excesses may include unresolved sources or more complicated propagation models. We illustrate that an exponential cutoff power-law component with an index of −2.40 and a cutoff energy of ∼30 TeV is able to account for such excesses.
The application of multiobjective evolutionary algorithms to many-objective optimization problems often faces challenges in terms of diversity and convergence. On the one hand, with a limited ...population size, it is difficult for an algorithm to cover different parts of the whole Pareto front (PF) in a large objective space. The algorithm tends to concentrate only on limited areas. On the other hand, as the number of objectives increases, solutions easily have poor values on some objectives, which can be regarded as poor bottleneck objectives that restrict solutions' convergence to the PF. Thus, we propose a coevolutionary particle swarm optimization with a bottleneck objective learning (BOL) strategy for many-objective optimization. In the proposed algorithm, multiple swarms coevolve in distributed fashion to maintain diversity for approximating different parts of the whole PF, and a novel BOL strategy is developed to improve convergence on all objectives. In addition, we develop a solution reproduction procedure with both an elitist learning strategy (ELS) and a juncture learning strategy (JLS) to improve the quality of archived solutions. The ELS helps the algorithm to jump out of local PFs, and the JLS helps to reach out to the missing areas of the PF that are easily missed by the swarms. The performance of the proposed algorithm is evaluated using two widely used test suites with different numbers of objectives. Experimental results show that the proposed algorithm compares favorably with six other state-of-the-art algorithms on many-objective optimization.
The key challenge of expensive optimization problems (EOP) is that evaluating the true fitness value of the solution is computationally expensive. A common method to deal with this issue is to seek ...for a less expensive surrogate model to replace the original expensive objective function. However, this method also brings in model approximation error. To efficiently solve the EOP, a novel scale-adaptive fitness evaluation (SAFE) method is proposed in this article to directly evaluate the true fitness value of the solution on the original objective function. To reduce the computational cost, the SAFE method uses a set of evaluation methods (EM) with different accuracy scales to cooperatively complete the fitness evaluation process. The basic idea is to adopt the low-accuracy scale EM to fast locate promising regions and utilize the high-accuracy scale EM to refine the solution accuracy. To this aim, two EM switch strategies are proposed in the SAFE method to adaptively control the multiple EMs according to different evolutionary stages and search requirements. Moreover, a neighbor best-based evaluation (NBE) strategy is also put forward to evaluate the solution according to its nearest high-quality evaluated solution, which can further reduce computational cost. Extensive experiments are carried out on the case study of crowdshipping scheduling problem in the smart city to verify the effectiveness and efficiency of the proposed SAFE method, and to investigate the effects of the two EM switch strategies and the NBE strategy. Experimental results show that the proposed SAFE method achieves better solution quality than some baseline and state-of-the-art algorithms, indicating an efficient method for solving EOP with a better balance between solution accuracy and computational cost.
Intelligent actuating materials have drawn enormous attention because of their potential applications in soft robots, smart sensors, bionics, etc. Aiming to integrate light, thermal, and humidity ...stimuli deformations and self-healing function into a single polymer, a smart actuating polyurethane material CPPU-50 is designed and successfully synthesized through co-polymerization of azobenzene-containing Azo-C
, polyethylene glycol 200 (PEG200), and 4,4'-diphenylmethane diisocyanate (MDI) at a ratio of 1:1:2. The obtained polyurethane CPPU-50 exhibits good photoinduced bending, thermal responsive shape memory effect, humidity triggered deflections and self-healing properties. Furthermore, an actuator combining light and thermal stimuli is created and the self-healing CPPU-50 film can withstand the object of 1800 times without tearing. This work can pave a way for further development of long-lived multi-stimuli-responsive actuating devices and intelligent materials.
The recent groundbreaking achievement in the synthesis of large‐sized single crystal C60 monolayer, which is covalently bonded in a plane using C60 as building blocks. The asymmetric lattice ...structure endows it with anisotropic phonon modes and conductivity. If these C60 are arranged in form of 1D fiber, the improved manipulation of phonon conduction along the fiber axis could be anticipated. Here, thermal properties of C60‐fiber, including thermal transfer along the C60‐fiber axis and across the interlayer interface are investigated using molecular dynamic simulations. Taking advantage of the distinctively hollow spherical structure of C60 building blocks, the spherical structure deformation and encapsulation induced thermal reduction can be up to 56% and 80%, respectively. By applying external electronic fields in H2O@C60 model, its thermal conductivity decreases up to 60%, which realizes the contactless thermal regulation. ln particular, the thermal rectification phenomenon is discovered by inserting atoms/molecules in C60 with a rational designed mass‐gradient, and its maximum thermal rectification factor is predicted to ≈45%. These investigations aim to achieve effective regulation of the thermal conductivity of C60‐fibers. This work showcases the potential of C60‐fiber in the realms of thermal management and thermal sensing, paving the way to C60‐based functional materials.
Drawing inspiration from the unique hollow structure of C60, various techniques for thermal regulation of endohedral C60 are explored. These techniques include strain engineering, mass‐gradient, and external electronic fields. The objective is to identify an effective approach for modulating the thermal conductivity of C60‐fibers. The results highlight the promising potential of C60‐fibers in the field of thermal management.
Aflatoxin B1 (AFB1) causes toxic effect and leads to organ damage in broilers. Marine algal polysaccharides (MAP) of Enteromorpha prolifera exert multiple biological activities, maybe have a ...potential detoxification effect on AFB1, but the related research in broilers is extremely rare. Therefore, the purpose of this study was to investigate whether MAPs can alleviate AFB1-induced oxidative damage and apoptosis of bursa of Fabricius in broilers. A total of 216 five-week-old male indigenous yellow-feathered broilers (with average initial body weight 397.35 ± 6.32 g) were randomly allocated to one of three treatments (6 replicates with 12 broilers per replicate), and the trial lasted 4 wk. Experimental groups were followed as basal diet (control group); basal diet mixed with 100 μg/kg AFB1 (AFB1 group, the AFB1 is purified form); basal diet with 100 μg/kg AFB1 + 2,500 mg/kg MAPs (AFB1 + MAPs group). The results showed that the diet with AFB1 significantly decreased the relative weight of bursa of Fabricius (P < 0.05), antioxidant enzymes activities of total superoxide dismutase (T-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione S-transferase (GST), and total antioxidation capacity (T-AOC), while increased malondialdehyde (MDA) content (P < 0.05). Besides, compared with AFB1 group, dietary MAPs improved the relative weight of bursa of Fabricius and activities of antioxidant enzymes (T-SOD, GSH-Px, CAT, GST) with decreased MDA contents (P < 0.05). Moreover, the consumption of AFB1 downregulated the mRNA expression of SOD1, SOD2, GSTA3, CAT1, GPX1, GPx3, GSTT1, Nrf2, HO-1, and p38MAPK (P < 0.05). Dietary MAPs upregulated the mRNA expression of SOD2, GSTA3, CAT1, GPX1, GSTT1, p38MAPK, Nrf2, and HO-1 in comparison with AFB1 group (P < 0.05). The histological analysis confirmed restoration of apoptotic cells of bursa of Fabricius (P < 0.01), which seen with MAPs supplemented broilers. Besides, dietary MAPs down-regulated the mRNA expression of caspase-3 and Bax (P < 0.05), while up-regulated the mRNA expression of Bcl-2 (P < 0.05) compared with AFB1 group. In addition, according to protein expression results, dietary MAPs up-regulated the protein expression level of antioxidant and apoptosis-associated proteins (Nrf2, HO-1, p38MAPK, Bcl-2) (P < 0.01), but down-regulated the protein expression level of caspase-3 and Bax (P < 0.01). In conclusion, dietary MAPs alleviated AFB1-induced bursa of Fabricius injury through regulating Nrf2-mediated redox and mitochondrial apoptotic signaling pathway in broilers.
Background and Aims
Hepatic ischemia–reperfusion injury (IRI) is a common complication of hepatectomy and liver transplantation. However, the mechanisms underlying hepatic IRI have not been fully ...elucidated. Regulator of G‐protein signaling 14 (RGS14) is a multifunctional scaffolding protein that integrates the G‐protein and mitogen‐activated protein kinase (MAPK) signaling pathways. However, the role of RGS14 in hepatic IRI remains unclear.
Approach and Results
We found that RGS14 expression increased in mice subjected to hepatic ischemia–reperfusion (IR) surgery and during hypoxia reoxygenation in hepatocytes. We constructed global RGS14 knockout (RGS14‐KO) and hepatocyte‐specific RGS14 transgenic (RGS14‐TG) mice to establish 70% hepatic IRI models. Histological hematoxylin and eosin staining, levels of alanine aminotransferase and aspartate aminotransferase, expression of inflammatory factors, and apoptosis were used to assess liver damage and function in these models. We found that RGS14 deficiency significantly aggravated IR‐induced liver injury and activated hepatic inflammatory responses and apoptosis in vivo and in vitro. Conversely, RGS14 overexpression exerted the opposite effect of the RGS14‐deficient models. Phosphorylation of TGF‐β‐activated kinase 1 (TAK1) and its downstream effectors c‐Jun N‐terminal kinase (JNK) and p38 increased in the liver tissues of RGS14‐KO mice but was repressed in those of RGS14‐TG mice. Furthermore, inhibition of TAK1 phosphorylation rescued the effect of RGS14 deficiency on JNK and p38 activation, thus blocking the inflammatory responses and apoptosis.
Conclusions
RGS14 plays a protective role in hepatic IR by inhibiting activation of the TAK1–JNK/p38 signaling pathway. This may be a potential therapeutic strategy for reducing incidences of hepatic IRI in the future.
Gluconeogenesis is a key interface between organic acid/amino acid/lipid and sugar metabolism. The aims of this article are four-fold. First, to provide a concise overview of plant gluconeogenesis. ...Second, to emphasise the widespread occurrence of gluconeogenesis and its utilisation in diverse processes. Third, to stress the importance of the vacuolar storage and release of Krebs cycle acids/nitrogenous compounds, and of the role of gluconeogenesis and malic enzyme in this process. Fourth, to outline the contribution of fine control of enzyme activity to the coordinate-regulation of gluconeogenesis and malate metabolism, and the importance of cytosolic pH in this.
Effective capture of radioactive iodine is of paramount importance for the safe and long‐term storage of fission products in the nuclear fuel cycle. Herein, a series of functionalized Th‐UiO‐66 MOFs ...was employed as a model to investigate the effects of substituents on iodine adsorption in both solution and vapor states. Sorption studies revealed that the electro‐donating amino group exhibits the most positive role on increasing the removal rate of iodine from cyclohexane and the uptake capacity of iodine vapor. Particularly, the disubstituted Th‐UiO‐66‐(NH2)2 can effectively remove 91.9 % of iodine (300 mg L−1) from cyclohexane and capture 969 mg g−1 iodine vapor, significantly higher than 59.6 % and 334 mg g−1 of untagged Th‐UiO‐66, respectively. In addition, the substituent effect on the radiolytic stability of MOFs was for the first time investigated, leading to the unearthing of one of the most radioresistant MOFs Th‐UiO‐66‐NH2 reported to date.
A systematic study on the effects of aromatic substitution on iodine adsorption was performed by employing Th‐UiO‐66 as a platform, giving rise to the disubstituted Th‐UiO‐66‐(NH2)2 with the best iodine sorption performance. Moreover, aromatic substitution was employed as a new strategy to enhance the radioresistance of MOFs.
Stochastic resonance (SR) is an important approach to detect weak vibration signals from heavy background noise and further realize mechanical incipient fault diagnosis. The stochastic resonance of a ...bistable Duffing oscillator is limited by strict small-parameter conditions, i.e., SR can only take place under small values of signal parameters (signal amplitude, frequency, and noise intensity). We propose a method to treat the large-parameter SR for this oscillator. The linear amplitude-transformed, time/frequency scale-transformed, and parameter-adjusted methods are presented and used to produce SR for signals with large-amplitude, large-frequency and/or large-intensity noise. Furthermore, we propose the weak-signal detection approach based on large-parameter SR in the oscillator. Finally, we employ two practical examples to demonstrate the feasibility of the proposed approach in incipient fault diagnosis.
•We introduce the stochastic resonance mechanism of a Duffing oscillator.•We propose methods to overcome the small-parameter limits of SR of this oscillator.•We propose a weak-signal detection approach based on this model.•We employ two practical examples to demonstrate the feasibility of the approach.
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