Search

The molecular model of nano-zirconia reinforced nitrile rubber （NBR） composite was established by molecular dynamics simulation. The reinforcement effects of three forms of nano-zirconia, namely, external filling, in-situ filling, and in-situ filling and coupling treatment on mechanical pro-perties of NBR were compared and analyzed, internal reinforcement mechanism of the mechanical properties of stator rubber was discussed from atomic level. The results showed that compared with pure NBR, the mechanical properties of NBR were significantly improved by introduction of three forms of nano-zirconia. The surface hydroxyl of in-situ filled nano-zirconia interacted with NBR to form hydrogen bond type dipole interaction. The addition of surfactant coupling agent bis-（3-triethoxysilane propyl） tetrasulfide further provided a chemical bridge with the rubber matrix, thus greatly improving the mechanical properties of NBR matrix. Compared with pure NBR system, the nano-zirconia filled in situ and treated by coupling had the best performance in enhancing the mechanical properties of NBR, and the young's mo-dulus, volume modulus and shear modulus of the composite system were improved the most. The conclusion that the addition of nano-zirconia improved the mechanical properties of stator rubber was verified by calculating the interface binding energy, non-bond energy, mean square displacement and diffusion coefficients.

Automatic sketch colorization has become an important research topic in computer vision.Previous methods intent to improve the colorization quality with advanced network architecture or innovative pipeline.However, they usually generate results with concentrated hue, unreasonable saturation and gray distribution.To alleviate these problems, this paper proposes a sketch colorization method with drawing priors.Inspired by the actual coloring process, this method learns the widely used drawing priors (such as hue variation, saturation contrast, and gray contrast) to improve the quality of automatic sketch colorization.Speci-fically, it incorporates pixel-level loss in the HSV color space to gain more natural results with less artifacts.Meanwhile, three heuristic loss functions that introduce the drawing priors such as hue variation, saturation and gray contrast are used to train our method to generate results with harmonious color composition.We compare our method with current state-of-the-art methods on test dataset constructed by real sketch images.Fréchet inception distance (FID) and mean opinion score (MOS) are adopted to measure the similarity between the distribution of real and generated images and the visual quality, respectively.Compared to the second-best method, the experimental results show that the FID of our method decreases by 21.00 and the MOS increases by 0.96, respectively.All the experimental results prove that the proposed method effectively improves the visual quality of automa-tic sketch colorization.

Molecular models of nitrile rubber (NBR) composites reinforced by carbon nanotube (CNT) (CNT/NBR composites) with different chirality and diameter were developed using the Materials Studio software, the mechanical properties of CNT/NBR composites were calculated via the constant strain method, and the effects of chirality and diameter of CNT on the mechanical properties of CNT/NBR composites were studied.The results indicated that compared with the armchair CNT and the zigzag CNT, the spiral CNT had the best reinforcement effect on the mechanical properties of CNT/NBR composites.The reinforcement effect of CNT on the mechanical properties of CNT/NBR composites was weakened with the increase of CNT diameter.

The southward extension of the Bangong-Nujiang Suture and the late Mesozoic tectonic affinity of the Tengchong Block have been subject to debate, and the Early Cretaceous magmatism in the eastern Tengchong Block provides a crucial window to address these issues. This paper reports comprehensive petrographic, geochemical, geochronological, and isotopic data of Early Cretaceous granitic rocks from the eastern Tengchong Block. Results show that these granitic rocks consist of monzogranites and granodiorites, with zircon U-Pb ages of 120.4–113.9 Ma. These granitic rocks are characterized by enrichments in large ion lithophile elements (e.g. Rb, U, K) and light rare earth elements, but depleted in high field strength elements (e.g. Nb, Ta, P, Ti), and have negative apatite εNd(t) values (−10.4 to −6.7) and negative zircon εHf(t) values (−11.7 to −1.2). The molar [Al2O3/(CaO + K2O + Na2O)] (A/CNK) values and whole-rock zircon saturated temperatures of the studied monzogranites of 1.04–1.09 and 714–799°C, respectively, indicate that they have I-type granite affinity. The presence of biotite indicative of I-type granite and the observation that P2O5 decrease with increasing SiO2 further indicated that the monzogranites have affinities of I-type granites. The petrography, geochemical and isotopic signatures of the studied monzogranites indicate that they originated from partial melting of mafic lower crustal rocks. The Na-rich granodiorites have elevated Na2O/K2O ratios and Na2O contents of 1.19–2.04 and 3.12–3.47 wt.%, respectively. These granodiorites also have relatively high Mg# values and the transition metal element Cr of 53.3–54.5 and up to 100 ppm, respectively. According to these isotopic and geochemical features and the occurrence of magnesiohornblende, we propose that the Na-rich granodiorites were derived from partial melting of ancient basaltic lower crust, with certain inputs of mantle materials in the magma source. Considering these results as well as published data, we finally propose that the Tengchong Block was likely the southeastern extension of the Lhasa Block and that these Early Cretaceous granitic rocks were formed in the setting of the volcanic arc due to westward subduction of the Bangong-Nujiang Tethys oceanic lithosphere beneath the Tengchong Block. [ABSTRACT FROM AUTHOR]

The Presenilin (Psn) gene is closely related to aging, but it is still unclear the role of Psn genes in skeletal muscle. Here, the Psn-UAS/Mhc-GAL4 system in Drosophila was used to regulate muscle Psn overexpression(MPO) and muscle Psn knockdown(MPK). Drosophila were subjected to endurance exercise from 4 weeks to 5 weeks old. The results showed that MPO and exercise significantly increased climbing speed, climbing endurance, lifespan, muscle SOD activity, Psn expression, Sirt1 expression, PGC-1α expression, and armadillo (arm) expression in aged Drosophila, and they significantly decreased muscle malondialdehyde levels. Interestingly, when the Psn gene is knockdown by 0.78 times, the PGC-1α expression and arm expression were also down-regulated, but the exercise capacity and lifespan were increased. Furthermore, exercise combined with MPO further improved the exercise capacity and lifespan. MPK combined with exercise further improves the exercise capacity and lifespan. Thus, current results confirmed that the muscle Psn gene was a vital gene that contributed to the healthy aging of skeletal muscle since whether it was overexpressed or knocked down, the aging progress of skeletal muscle structure and function was slowed down by regulating the activity homeostasis of Sirt1/PGC-1α pathway and Psn/arm pathway. Exercise enhanced the function of the Psn gene to delay skeletal muscle aging by up regulating the activity of the Sirt1/PGC-1α pathway and Psn/arm pathway. [ABSTRACT FROM AUTHOR]

Based on molecular dynamics(MD), nitrile rubber(NBR) models with cross-linking densities of 0, 10%, 15% and 20% were established, and the glass transition temperature and mechanical property of the NBR model under different cross-linking densities were predicted.The results showed that the glass transition temperature of NBR with a cross-linking density of 0-20% increased with increasing cross-linking density, and the mechanical property first increased and then decreased with the increase of cross-linking density. When the cross-linking density was 10%, NBR could obtain the optimal cross-linking network structure, and its mechanical property was better.

A cylindrical representative volume element model of polymer nano-composites reinforced by carbon nanotubes under a fixed tension stress was developed. The stress distribution in each layer of carbon nanotubes was numerically studied through developing a shear lag model. Finite element analysis was adopted to validate the results obtained by shear lag analysis. The effects of layer numbers, aspect ratio, content of carbon nanotubes and three kinds of matrix materials of epoxy resin, nylon and polymethyl methacrylate on the stress distribution in each layer of carbon nanotubes were analyzed. The results show that the stress distribution in graphene sheets of carbon nanotubes is significant influenced by layer numbers and the aspect ratio of carbon nanotubes under a fixed tension stress. The saturation stress of carbon nanotubes is decreased with the increase of the layer numbers and the value correlated with the number of layers. Single-walled carbon nanotubes are observed to perform the best utilization of its properties. It is found that the effective length is increased with the increase of the aspect ratio of carbon nanotubes. Significant increase of the saturation stress and decrease of the effective length of carbon nanotubes are observed respectively with the decrease of the content of carbon nanotubes. It is also indicated that different polymer matrix materials play little effect on the stress distribution in carbon nanotubes.

A cylindrical representative volume element model of polymer nano-composites reinforced by carbon nanotubes under a fixed tension stress was developed. The stress distribution in each layer of carbon nanotubes was numerically studied through developing a shear lag model. Finite element analysis was adopted to validate the results obtained by shear lag analysis. The effects of layer numbers, aspect ratio, content of carbon nanotubes and three kinds of matrix materials of epoxy resin, nylon and polymethyl methacrylate on the stress distribution in each layer of carbon nanotubes were analyzed. The results show that the stress distribution in graphene sheets of carbon nanotubes is significant influenced by layer numbers and the aspect ratio of carbon nanotubes under a fixed tension stress. The saturation stress of carbon nanotubes is decreased with the increase of the layer numbers and the value correlated with the number of layers. Single-walled carbon nanotubes are observed to perform the best utilization of its properties. It is found that the effective length is increased with the increase of the aspect ratio of carbon nanotubes. Significant increase of the saturation stress and decrease of the effective length of carbon nanotubes are observed respectively with the decrease of the content of carbon nanotubes. It is also indicated that different polymer matrix materials play little effect on the stress distribution in carbon nanotubes.

In view of the characteristics of strong randomness and low direct prediction accuracy of daily power of runoff hydropower stations, this paper uses the Extreme-point Symmetric Mode Decomposition (ESMD) to smooth the power sequence. Combined with the Least-Square Support Vector Machines (LSSVM), a combined prediction model based on ESMD-LSSVM is established. The daily power time series of a runoff hydropower station in Northwest China in 2020 is selected for example analysis, and compared with the prediction results of single model SVM, LSSVM, BP and combined model ESMD-SVM, ESMD-BP. The results show that: ➀ PACF analysis shows that the feature vectors of each subsequence after ESMD decomposition are different, which reflects the complexity and variability of the daily power of runoff hydropower stations. ➁ Compared with the single model, the combined model has stronger generalization ability and more accurate prediction of the power mutation point in the time series. ➂ The daily power of ESMD-LSSVM combined model has good prediction effect, which provides a new method reference for the daily power time series prediction of runoff hydropower station. [ABSTRACT FROM AUTHOR]

MXenes have the excellent electrochemical properties as electrode of supercapacitors. Using density functional theory, we investigated the electronic properties and quantum capacitance of Zr2CO2 with atomic swap. The atomic swap results in the appearance of Frenkel‐type defect and Schottky defect. The negative binding energy confirms the stability of the studied systems. The atomic swap makes ZrC1, ZrC2, ZrO1, ZrO2, CO2 systems maintain the indirect semiconductor character, and CO2 system has the direct semiconductor character. The thermionic emission performance of Zr2CO2 MXene is greatly improved by atomic swap. ZrO1 and ZrO2 systems in aqueous system are appropriate anode materials. The wide voltage has little effect on the electrode type for perfect Zr2CO2, ZrO1, ZrO2, CO1, and CO2 systems, but changes ZrC1 and ZrC2 systems from cathode material in aqueous system to anode material in ionic/organic system. The work function and effective mass are also explored. [ABSTRACT FROM AUTHOR]

Population genetic diversity was estimated from forty-four individual ginseng (Panax ginsengC.A. Meyer) plants collected from seven geographical populations located in Heilongjiang, Liaoning, and Jilin Provinces of China as well as the People’s Republic of Korea by using randomly amplified polymorphic DNA (RAPD) markers. Overall, 41 polymorphic loci were amplified using ten primer pairs. The polymorphism percentage ranged from 50% to 100% among seven local populations of ginseng, indicating that there is plentiful genetic diversity in wild ginseng populations. The genetic diversity at the species level was higher than that at the population level. Variance analysis showed that there was a significant difference among populations in genetic diversity. The genetic differentiation coefficient (i.e., FST) indicates that 43% of the variation occurred among populations, which indicates that substantial genetic differentiation occurred among populations. At the same time, the measured value of gene flow (Nm) was 0.66 based on the observed genetic differentiation coefficient among populations, suggesting there was moderate gene flow among populations.