49 research outputs found

    The Effects of Campus Bump on Drivers’ Fixation Dispersion and Speed Reduction

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    To evaluate the effects of campus speed bumps on drivers’ speed and fixation distribution, a quasinaturalistic driving test was conducted on a Chinese campus. Seven randomly selected drivers, wearing the Dikablis eye tracking devices, were required to drive an OPEL SUV passing the speed bumps. The area close to the bump was divided into ten subsegments (15 m for each one). The degree of fixation dispersion within each subsegment was defined as the distance from each subcenter to the whole fixation center. All traffic data were recorded using mounted camera, and the trajectories were extracted in Matlab. The speed and trajectory data was divided into two groups: the before group for bump-free case and the after group for a 5 cm bump case. The observational before-after analysis shows statistical significance between the two cases. The individual vehicular speed analysis reveals that bump reduces nearly 60% of vehicles’ speeds to a certain extent within the distance from 30 m upstream to 15 m downstream. The drivers’ fixation points begin to disperse 30–45 m before they see the bump, and it falls back to normal level 15–30 m downstream of the bump. These findings will help engineers install speed bumps at the most appropriate locations

    Photoflexoelectric effect in halide perovskites

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    Harvesting environmental energy to generate electricity is a key scientific and technological endeavour of our time. Photovoltaic conversion and electromechanical transduction are two common energy-harvesting mechanisms based on, respectively, semiconducting junctions and piezoelectric insulators. However, the different material families on which these transduction phenomena are based complicate their integration into single devices. Here we demonstrate that halide perovskites, a family of highly efficient photovoltaic materials, display a photoflexoelectric effect whereby, under a combination of illumination and oscillation driven by a piezoelectric actuator, they generate orders of magnitude higher flexoelectricity than in the dark. We also show that photoflexoelectricity is not exclusive to halides but a general property of semiconductors that potentially enables simultaneous electromechanical and photovoltaic transduction and harvesting in unison from multiple energy inputs

    Optimizing scheduling of long-term highway work zone projects

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    The impacts of work zone activities can be summarized into the following types: safety impact (on both motorists and workers), mobility impact, economic considerations, environmental concerns, user cost as well as contractor’s maintenance cost. Various interest subjects may focus on different aspects of the six areas identified above. In this study, the impacts of scheduling long-term work zone activities are analyzed from the perspective of traffic agencies and jurisdictions. A bi-level genetic algorithm (GA)-based optimization model is formulated to determine the optimal starting date of each work zone project. The upper-level subprogram minimizes the total travel time over the entire planning horizon, while the lower-level subprogram is a user equilibrium (UE) problem where all users try to find the route that minimizes their own travel time. The demand, and the number of work zones as well as their durations are assumed to be fixed and given a priori. The proposed GA model is applied to the Sioux Falls network, which has 76 links and 24 origin–destination (O–D) pairs. The results of the numerical example indicate that the proposed model can effectively identify the near-optimal solution of the long-term work zone scheduling problem

    The Effects and Toxicity of Different Pyrene Concentrations on <i>Escherichia coli</i> Using Transcriptomic Analysis

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    Pyrene is a pollutant in the environment and affects the health of living organisms. It is important to understand microbial-mediated pyrene resistance and the related molecular mechanisms due to its toxicity and biodegradability. Due to the unclear response mechanisms of bacteria to PAHs, this study detected the transcriptional changes in Escherichia coli under different pyrene concentrations using transcriptome sequencing technology. Global transcriptome analysis showed that the number of differentially expressed genes (DEGs) in multiple metabolic pathways increased with increasing concentrations of pyrene. In addition, the effects and toxicity of pyrene on Escherichia coli mainly included the up-regulation and inhibition of genes related to carbohydrate metabolism, membrane transport, sulfate reduction, various oxidoreductases, and multidrug efflux pumps. Moreover, we also constructed an association network between significantly differentially expressed sRNAs and key genes and determined the regulatory relationship and key genes of Escherichia coli under pyrene stress. Our study utilized pyrene as an exogenous stress substance to investigate the possible pathways of the bacterial stress response. In addition, this study provides a reference for other related research and serves as a foundation for future research

    Study of a Nano-SiO<sub>2</sub> Microsphere-Modified Basalt Flake Epoxy Resin Coating

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    Basalt flakes (BFs) have been widely used in recent years as a novel anticorrosion material in the marine industry to prevent the corrosion of metal substrates. In this study, BFs were modified with 1&#8315;7&#8240; nano-SiO2 microspheres, and a modified BF epoxy coating was successfully prepared. Experimental results showed that the BF epoxy resin coating modified with 3&#8240; nano-SiO2 microspheres exhibited excellent chemical durability (surface weight loss rate of 2.2% in the alkali solution and only 1.1% in the acid solution at room temperature after 480 h), low water infiltration (water absorption of 0.72% after 480 h), and good mechanical performance (tensile strength of approximately 33.4 MPa). This study proves the feasibility of using nano-SiO2 microspheres to modify BF epoxy resin coating and enhance the chemical durability and mechanical properties provided by the coating

    Virus diversity and interactions with hosts in deep-sea hydrothermal vents

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    Background The deep sea harbors many viruses, yet their diversity and interactions with hosts in hydrothermal ecosystems are largely unknown. Here, we analyzed the viral composition, distribution, host preference, and metabolic potential in different habitats of global hydrothermal vents, including vent plumes, background seawater, diffuse fluids, and sediments. Results From 34 samples collected at eight vent sites, a total of 4662 viral populations (vOTUs) were recovered from the metagenome assemblies, encompassing diverse phylogenetic groups and defining many novel lineages. Apart from the abundant unclassified viruses, tailed phages are most predominant across the global hydrothermal vents, while single-stranded DNA viruses, including Microviridae and small eukaryotic viruses, also constitute a significant part of the viromes. As revealed by protein-sharing network analysis, hydrothermal vent viruses formed many novel genus-level viral clusters and are highly endemic to specific vent sites and habitat types. Only 11% of the vOTUs can be linked to hosts, which are the key microbial taxa of hydrothermal habitats, such as Gammaproteobacteria and Campylobacterota. Intriguingly, vent viromes share some common metabolic features in that they encode auxiliary genes that are extensively involved in the metabolism of carbohydrates, amino acids, cofactors, and vitamins. Specifically, in plume viruses, various auxiliary genes related to methane, nitrogen, and sulfur metabolism were observed, indicating their contribution to host energy conservation. Moreover, the prevalence of sulfur-relay pathway genes indicated the significant role of vent viruses in stabilizing the tRNA structure, which promotes host adaptation to steep environmental gradients. Conclusions The deep-sea hydrothermal systems hold untapped viral diversity with novelty. They may affect both vent prokaryotic and eukaryotic communities and modulate host metabolism related to vent adaptability. More explorations are needed to depict global vent virus diversity and its roles in this unique ecosystem

    Inverted structure polymer solar cells with solution processed zinc oxide thin film as an electron collection Layer

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    A solution-processed zinc oxide (ZnO) thin film as an electron collection layer for polymer solar cells (PSCs) with an inverted device structure was investigated. Power conversion efficiencies (PCEs) of PSCs made with a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) are 3.50% and 1.21% for PSCs with and without the ZnO thin film, respectively. Light intensity dependence of the photocurrent and the capacitance-voltage measurement demonstrate that the increased PCEs are due to the restriction of the strong bimolecular recombination in the interface when a thin ZnO layer is inserted between the polymer active layer and the ITO electrode. These results demonstrate that the ZnO thin film plays an important role in the performance of PSCs with an inverted device structure

    Dissociation of Diglycolamide Complexes of Ln<sup>3+</sup> (Ln = La–Lu) and An<sup>3+</sup> (An = Pu, Am, Cm): Redox Chemistry of 4f and 5f Elements in the Gas Phase Parallels Solution Behavior

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    Tripositive lanthanide and actinide ions, Ln<sup>3+</sup> (Ln = La–Lu) and An<sup>3+</sup> (An = Pu, Am, Cm), were transferred from solution to gas by electrospray ionization as Ln­(L)<sub>3</sub><sup>3+</sup> and An­(L)<sub>3</sub><sup>3+</sup> complexes, where L = tetramethyl-3-oxa-glutaramide (TMOGA). The fragmentation chemistry of the complexes was examined by collision-induced and electron transfer dissociation (CID and ETD). Protonated TMOGA, HL<sup>+</sup>, and Ln­(L)­(L–H)<sup>2+</sup> are the major products upon CID of La­(L)<sub>3</sub><sup>3+</sup>, Ce­(L)<sub>3</sub><sup>3+</sup>, and Pr­(L)<sub>3</sub><sup>3+</sup>, while Ln­(L)<sub>2</sub><sup>3+</sup> is increasingly pronounced beyond Pr. A C–O<sub>ether</sub> bond cleavage product appears upon CID of all Ln­(L)<sub>3</sub><sup>3+</sup>; only for Eu­(L)<sub>3</sub><sup>3+</sup> is the divalent complex, Eu­(L)<sub>2</sub><sup>2+</sup>, dominant. The CID patterns of Pu­(L)<sub>3</sub><sup>3+</sup>, Am­(L)<sub>3</sub><sup>3+</sup>, and Cm­(L)<sub>3</sub><sup>3+</sup> are similar to those of the Ln­(L)<sub>3</sub><sup>3+</sup> for the late Ln. A striking exception is the appearance of Pu­(IV) products upon CID of Pu­(L)<sub>3</sub><sup>3+</sup>, in accord with the relatively low Pu­(IV)/Pu­(III) reduction potential in solution. Minor divalent Ln­(L)<sub>2</sub><sup>2+</sup> and An­(L)<sub>2</sub><sup>2+</sup> were produced for all Ln and An; with the exception of Eu­(L)<sub>2</sub><sup>2+</sup> these complexes form adducts with O<sub>2</sub>, presumably producing superoxides in which the trivalent oxidation state is recovered. ETD of Ln­(L)<sub>3</sub><sup>3+</sup> and An­(L)<sub>3</sub><sup>3+</sup> reveals behavior which parallels that of the Ln<sup>3+</sup> and An<sup>3+</sup> ions in solution. A C–O<sub>ether</sub> bond cleavage product, in which the trivalent oxidation state is preserved, appeared for all complexes; charge reduction products, Ln­(L)<sub>2</sub><sup>2+</sup> and Ln­(L)<sub>3</sub><sup>2+</sup>, appear only for Sm, Eu, and Yb, which have stable divalent oxidation states. Both CID and ETD reveal chemistry that reflects the condensed-phase redox behavior of the 4f and 5f elements
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