•Both substitutional doped and interstitial N-doped TiO2 is prepared by a simple annealing method.•The photocatalytic activity toward decomposing benzene of N-TiO2 is higher than that of ...NAM-TiO2.•The surface hydroxyl group and different location of nitrogen in the lattice is responsible for the distinct photocatalytic activity.•The presence of oxygen favors the formation of interstitial nitrogen dopant during synthesis.•The deep Ni-energy level in bandgap tends to form the recombination center.
Nitrogen-doped TiO2 nanomaterial attracts enormous attention due to its excellent visible photocatalytic activity. A simple annealing method assisted by adjusting gas composition to control the positions of nitrogen dopants in TiO2 lattice is presented. The nitrogen doping sites are confirmed by XPS. The photo-degradation results of gaseous benzene under visible light illumination reveal that photocatalytic activity in as-prepared samples containing the substitutional nitrogen species is higher than that in samples containing interstitial nitrogen species. The improvement of photocatalytic performance is ascribed to the increased amounts of surface hydroxyl group in N-TiO2 samples. The efficient separation of electron-hole pairs was also responsible for the enhanced photocatalytic activity. In addition, an important conclusion is pointed out: the presence of oxygen during annealing process has an important effect on the formation of interstitial nitrogen dopants. The present work is believed to have guiding significance for preparing nitrogen-doped TiO2 with high photocatalytic activity.
Graphene (GR)-wrapped WO3 nanosphere composite was synthesized by using a facile sol–gel method. The morphology and structural properties of the GR-WO3 nanocomposites were characterized by ...field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. The GR-wrapped WO3 nanospheres composite exhibits p-type gas sensing behavior and the response of GR-WO3 sensor toward NO2 shows a linear increase with an increase in the concentration from 7 to 56ppm at room temperature. Upon exposure to 56ppm NO2, its response value becomes 40.8%, but there is no responsiveness for the sensors based on pure WO3 and graphene sensors. The effective charge transfer through chemically bonded interfacial contact between graphene and WO3 nanospheres is proposed to be responsible for the room temperature sensing performance. This work may provide a new insight into the structural design of GR-base nanocomposites and has a potential prospect in the environment monitoring or disease detection of NO2 at room temperature.
Nitrogen-doped TiO sub(2) nanomaterial attracts enormous attention due to its excellent visible photocatalytic activity. A simple annealing method assisted by adjusting gas composition to control the ...positions of nitrogen dopants in TiO sub(2) lattice is presented. The nitrogen doping sites are confirmed by XPS. The photodegradation results of gaseous benzene under visible light illumination reveal that photocatalytic activity in as-prepared samples containing the substitutional nitrogen species is higher than that in samples containing interstitial nitrogen species. The improvement of photocatalytic performance is ascribed to the increased amounts of surface hydroxyl group in N-TiO sub(2) samples. The efficient separation of electron-hole pairs was also responsible for the enhanced photocatalytic activity. In addition, an important conclusion is pointed out: the presence of oxygen during annealing process has an important effect on the formation of interstitial nitrogen dopants. The present work is believed to have guiding significance for preparing nitrogen-doped TiO sub(2) with high photocatalytic activity.
Calcified coccolithophores, a diverse and widely distributed group of marine microalgae, produce biogenic calcite in the form ofcoccoliths located on the cell surface. Using batch incubations of the ...coccolithophorid Pleurochrysis carterae, we investigated the responses of this calcification process to iron concentrations by changing the iron supply in the initial culture media from a normal concentration to 1 ppm （parts per million）, 5 ppm, and 10 ppm. Time-dependent measurements of cell population, production of inorganic carbon （coccoliths）, and organic carbon （organic cellular components） showed that elevated iron supply in the growth medium of P. carterae stimulates carbon sequestration by increasing growth along enhanced photosynthetic activity and calcification. In addition, the acquired time-dependent UV-Vis and FT-IR spectra revealed that iron fertilization- enhanced coccolith calcification is accompanied by a crystalline phase transition from calcite to aragonite or amorphous phase. Our results suggest that iron concentration has a significant influence on the marine carbon cycle of coccolithophores.
Hyperlipidemia is an independent risk factor in the devel- opment of ischemic heart disease, which can increase myo- cardial susceptibility to ischemia/reperfusion （I/R） injury. Ischemic ...postconditioning （PostC） has now been demon- strated as a novel strategy to harness nature＇s protection against myocardial I/R injury in normal conditions. However, the effect of PostC on hyperlipidemic animals remains elusive. It has been shown in our previous study that PostC reduces the myocardial I/R injury, and hypoxia- inducible factor-1α （HIF-1α） may play an important role in the cardioprotective mechanisms of PostC on normal rats. Here, we tested the hypothesis that the cardioprotec- tion of PostC on hyperlipidemic rats is associated with the up-regulated HIF-1α expression. Male Wistar rats were fed with a high-fat diet for 8 weeks, and then randomly div- ided into five groups： sham, I/R, dimethyloxalylglycine （DMOG） ＋ I/R, PostC, and DMOG ＋ PostC group. The detrimental indices induced by I/R injury included infarct size, plasma creatine kinase （CK） activity and caspase-3 ac- tivity. The results showed that PostC could reduce the infarct size, when compared with the I/R group, which was consistent with the significant lower levels of plasma CK activity and caspase-3 activity, and that it increased the ex- pression of HIF-1α in hyperlipidemic rats. When DMOG was given before PostC to up-regulate HIF-1α protein level, the degree of I/R injury was attenuated. In conclu- sion, these data suggested that the up-regulation of HIF-1α may be one of the cardioprotective mechanisms of PostC against I/R injury in hyperlipidemic rats.
This paper studied the thermal stresses of ceramicl metal gradient thermal barrier coating which combines the conceptions of ceramic thermal barrier coating （TBC） and functionally gradient material ...（FGM）. Thermal stresses and residual thermal stresses were calculated by an ANSYS finite element analysis software. Negative thermal expansion coefficient method was proposed and element birth and death method was applied to analyze the residual thermal stresses which have non-uniform initial temperature field. The numerical results show a good agreement with the analytical results and the experimental results.
The Bacterial Foraging Optimization (BFO) algorithm is a swarm intelligent algorithm widely used in various optimization problems. However, BFO suffers from multiple drawbacks, including slow ...convergence speed, inability to jump out of local optima and fixed step length. In this study, an enhanced BFO with chaotic chemotaxis step length, Gaussian mutation and chaotic local search (CCGBFO) is proposed for overcoming the existing weakness of original BFO. First, a chaotic chemotaxis step length operation is used to produce adaptive chemotaxis step length. Then, by combining the optimal position in the current bacteria with the Gaussian mutation operation to make full use of the information of the optimal position. Finally, a chaotic local search is introduced into the chemotaxis step to ensure that the algorithm can explore a large search space in the early stage. The performance of CCGBFO was evaluated on a comprehensive set of numerical benchmark functions including IEEE CEC2014 and CEC2017 problems. In addition, CCGBFO was also used to tune the key parameters of kernel extreme learning machine for dealing with the real-world problems. The experimental results show that the proposed CCGBFO significantly outperforms the original BFO in terms of both convergence speed and solution accuracy.
•This paper proposes an enhanced Bacterial Foraging Optimization (BFO) algorithm for global optimization.•Chaotic chemotaxis step length, Gaussian mutation and chaotic local search are integrated with BFO algorithm.•The effectiveness was proved by the extensive results on benchmark problems and real-world problems.
The computational modeling of human visual attention has received much attention in recent decades. In advanced industrial applications, it has been demonstrated that computational visual attention ...models (CVAMs) can predict visual attention very similarly to human visual attention. However, it is controversial whether the driver's eye fixation location (EFL) or the predicted eye fixation location of computational visual attention models is more reliable and helpful for actual driving. To address this issue, an open database of videos taken under the most common 18 driving conditions in everyday driving has been established. In experiments using this database, expert drivers found that it was not sufficient for drivers to rely on only one of the two EFLs. Based on this finding, a hybrid EFL recommendation strategy is proposed for improving driving safety. By extracting visual characteristics from human dynamic vision, the performance of the proposed recommendation method demonstrates its potential value in these collected driving tasks. In addition, the visual comfort of driving is further addressed to enhance the safety of driving. From the results of experiments on 108 driving video clips taken of the most common 18 real driving conditions, it is confirmed that the proposed EFL recommendation achieves an experience rating of driving comfort between 88.1 and 92.7 out of 100.
•The influence of nano carbons on the thermophysical parameters of PCM was tested.•The thermal behavior was observed using thermocouples and an infrared camera.•Nano graphite was more effective to ...improve the melting of PCMs.•Melting time was shortened by 21% with 0.06 wt% nano graphite with dispersant.
Thermal energy storage performance of a paraffin-based phase change material (PCM) enhanced by nano graphite and nano coconut shell charcoal was investigated. The nano carbon concentration was 0.02, 0.06, and 0.10 wt%, respectively. To understand the influence of nano carbons on the thermal behavior of PCMs, the melting process of nano-enhanced PCMs (NePCMs) was monitored using thermocouples and an infrared camera, in comparison with the melting process of pure paraffin. It was found that the melting process of NePCMs without dispersant was accelerated with nano carbons at concentration of 0.02 wt%, although the thermal conductivity of NePCMs with higher concentrations was higher. With increasing concentration, the melting process was decelerated because of the agglomeration of nano carbons and the suppression of natural convection. To eliminate the agglomeration, Span 80 and oleic acid were used as dispersants for the PCMs with 0.06 wt% and 0.10 wt% nano graphite. The melting process was accelerated further with the increasing concentration of the nano graphite. The shortest melting time was realized using 0.06 wt% nano graphite and 2.0 wt% oleic acid, which was 21% shorter than the pure paraffin. Moreover, it was noticed that the data from thermocouples were not able to represent the melting process accurately because of the limited measuring points, especially for the melting process with agglomeration and sedimentation.
Moth-flame optimization (MFO) is a widely used nature-inspired algorithm characterized by a simple structure with simple parameters. However, for some complex optimization tasks, especially the high ...dimensional and multimodal problems, MFO may have problems with convergence or tend to fall into local optima. To overcome these limitations, here a series of new variants of MFO are proposed by combining MFO with Gaussian mutation (GM), Cauchy mutation (CM), Lévy mutation (LM) or the combination of GM, CM and LM. Specifically, GM is introduced into the basic MFO to improve neighborhood-informed capability. Then, CM with a large mutation step is adopted to enhance global exploration ability. Finally, LM is embedded to increase the randomness of search agents’ movement. The best variant of MFO was compared to 15 state-of-the-art algorithms and 4 well-known advanced optimization approaches on a comprehensive set of 23 benchmark problems and 30 CEC2017 benchmark tasks. The experimental results demonstrate that the three strategies can significantly boost exploration and exploitation capabilities of the basic MFO.
