A Study of Fatal Pedestrian Crashes at Rural Low Volume Road Intersections in Southwest China

Objective: Although intersections correspond to a small proportion of the entire roadway system, they account for a disproportionally high number of fatal pedestrian crashes, especially in rural roads situated in low- and middle-income countries. This paper examines pedestrian safety at rural intersections and suggests applicable accident prevention treatments by providing an in-depth analysis of 28 fatal pedestrian crashes from eight low volume roads in Southwest China. Methods: The Driving Reliability and Error Analysis Method (DREAM) is a method to support a systematic classification of accident causation information and to facilitate aggregation of that information into patterns of contributing factors. This is the first time DREAM was used to analyze pedestrian-vehicle crashes and provide suggestions for road improvements in China. Results: The key issues adversely affecting pedestrian safety can be organized in four distinctive thematic categories, namely deficient intersection safety infrastructure, lack of pedestrian safety education, inadequate driver training and insufficient traffic law enforcement. Given that resources for traffic safety investments in rural areas are limited, it is determined that the potential countermeasures should focus on low-cost, easily implementable and long-lasting measures increasing the visibility and predictability of pedestrian movement and reducing speeding and irresponsible driving for drivers and risk-taking behaviors for pedestrians. Conclusions: Accident prevention treatments are suggested based on their suitability for rural areas in Southwest China. These countermeasures include introducing better access management and traffic calming treatments, providing more opportunities for pedestrian education and enhancing the quality of driver training and traffic law enforcement

Calcium-magnesium-alumino-silicate induced degradation of La2(Zr0.7Ce0.3)2O7/YSZ double-ceramic–layer thermal barrier coatings prepared by electron beam-physical vapor deposition

During last decades, much effort has been made to develop new alternative thermal barrier coating (TBC) to traditional YSZ for applications above 1250oC. La2(Zr0.7Ce0.3)2O7(LZ7C3) is deemed as a very promising TBC candidate for advanced gas turbine because of its extremely low thermal conductivity, high sintering resistance and phase stability from room temperature to 1600oC. Thermal cycling with a gas burner showed that the LZ7C3/YSZ double-ceramic-layer (DCL) coatings prepared by electron beam-physical vapor deposition (EB-PVD) or atmospheric plasma spraying had a much longer lifetime than that of YSZ coating at 1250± 50oC.The use of the new TBC can allow higher gas temperatures, resulting in further improved thermal efficiency and engine performance. However, at these high operating temperatures, TBCs become susceptible to attack by calcium-magnesium-alumino-silicate (CMAS, relative to the main chemical components Ca, Mg, Al and Si) deposits resulting from the ingestion of siliceous minerals (dust, sand, volcanic ash, runway debris) with the intake air. CMAS becomes molten at temperatures above 1200oC and then rapidly penetrates the TBCs by capillary force, resulting in the loss of strain tolerance and premature failure of the coatings. In this paper, CMAS induced degradation of LZ7C3/YSZ DCL coatings prepared by EB-PVD method were investigated. Hot corrosion tests were performed at 1250oC at durations varying from 0.5 h to 24 h. It is observed that the infiltration of CMAS in the intercolumnar gaps was largely suppressed in the case of EB-PVD LZ7C3 coating. The penetration depth rarely exceeded 40 μm below the original surface even after 24 h exposure at 1250oC. This was ascribed to rapid dissolution of the LZ7C3 and essentially concurrent formation of a sealing layer made of crystalline apatite and fluorite phases, which is consistent with the observation on Gd2Zr2O7. However, large vertical cracks would form in the EB-PVD LZ7C3 coating during thermal cycling as a result of re-crystallization, sintering and thermal expansion mismatch between ceramic coating and substrate. These vertical cracks can also act as channels to CMAS melt infiltration. Since the kinetics of the dissolve-reprecipitation reaction was slower than the infiltration rate of CMAS in the vertical crack, the majority of vertical cracks were not sealed. As a result, CMAS flowed down to the LZ7C3/YSZ interface along the vertical cracks, and then easily penetrated the YSZ buffer layer by capillary force. Chemical interaction also occurred in the YSZ buffer layer. What\u27s more, the YSZ layer in the DCL coating even underwent a severer CMAS attack than the single YSZ coating. After 4 h CMAS exposure, the YSZ layer of the LZ7C3/YSZ bilayer coating was totally dissolved by molten CMAS followed by precipitation of a large number of globular ZrO2 particles, while the single YSZ coating just suffered a slight degradation in the same experimental conditions and still kept its columnar structure. The probable reason was that the CMAS melt in the YSZ layer of the DCL coating had a higher CaO/SiO2 ration than the original CMAS composition due to the formation of apatite phase when CMAS reacted with the upper LZ7C3 layer. The initial Si: Ca ratio (Si: Ca≈1.4) in CMAS melt is less than the corresponding apatite (Si: Ca≈3), leading to progressive CaO enrichment during apatite crystallization. For this reason, it is suggested that the effectiveness of the CMAS mitigation strategy for YSZ TBCs by adopting a so-called CMAS-resistant top layer needs to be assessed in the context of more realistic conditions. If the formation of large vertical cracks in TBCs was not avoided, this CMAS mitigation approach may not as effective as expected

Confined FeNi alloy nanoparticles in carbon nanotubes for photothermal oxidative dehydrogenation of ethane by carbon dioxide

Oxidative dehydrogenation of ethane with CO2 (ODEC) is an attractive reaction for reduction of carbon footprints and ethene production. In this work, we present photothermal catalysis on confined bimetal catalysts for ODEC. Carbon nanotubes confined non-noble bimetal alloy (i.e., CoNi@CNTs and FeNi@CNTs) catalysts were prepared and FeNi@CNTs showed effective performance in photothermal catalytic ODEC to ethene. Experiments and simulations reveal that UV and visible lights (420 – 490 nm) are responsible for ODEC and non-oxidative dehydrogenation of ethane, respectively, to ethene. Additionally, ODEC to ethene is preferred to C-C cracking to methane on FeNi@CNTs in light ( \u3e 490 nm)-induced thermocatalysis. The photothermal effect turns more significant when introduced into thermocatalytic ODEC (500 °C), with ethene generation at one order of magnitude. This work advances new mechanism of photo-mediated catalysis and sheds light on utilization of full-spectrum solar energy and non-noble metallic catalysts for ethene production and CO2 recycling at moderate conditions

Effects of Different Storage Conditions on the Browning Degree, PPO Activity, and Content of Chemical Components in Fresh Lilium Bulbs (Liliumbrownii F.E.Brown var. viridulum Baker.)

Although Lilium brownii (L. brownii) bulbs are popular fresh vegetables, a series of quality problems still remain after harvest. In this study, fresh L. brownii bulbs were placed in the dark at 25, 4, and −20 °C and under light at 25 °C from 0 to 30 days; the chemical compositions were analyzed by ultraviolet spectrophotometry (UV) and high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS). During the 30-day storage period, the browning degree increased over the storage time and with increasing temperature, but the contents of proteins and free amino acids decreased and were aggravated by light. The total polyphenol content increased until the 6th day at 25 °C (dark or light), but it did not significantly accumulate at −20 or 4 °C. The reducing sugar content showed a dynamic balance, but the total polysaccharide content decreased constantly in the four storage conditions. The polyphenol oxidase (PPO) activity increased with storage time and increasing temperature, while it was inhibited by light. The increase rates of malondialdehyde (MDA) content at −20 °C and light (25 °C) were higher than those at 4 and 25 °C. In addition, 12 secondary metabolites were identified, most of which accumulated during the storage period, for example, 1-O-feruloyl-3-O-β-D-glucopyranosylglycerol; 1,3-O-di-p-coumaroylglycerol; 1-O-feruloyl-3-O-p-coumaroylglycerol; and 1,2-O-diferuloylglycerol. The variations in nutrient levels had a low correlation with browning, but the variations in MDA, PPO, and secondary metabolite (phenolic acids) levels had a high correlation with browning. In conclusion, fresh L. brownii bulbs should be stored at a low temperature (4 °C) and in dark condition, and browning bulbs are excellent materials for secondary metabolite utilization

Effects of Different Storage Conditions on the Browning Degree, PPO Activity, and Content of Chemical Components in Fresh <i>Lilium</i> Bulbs (<i>Lilium</i><i>brownii</i> F.E.Brown var. <i>viridulum</i> Baker.)

Although Lilium brownii (L. brownii) bulbs are popular fresh vegetables, a series of quality problems still remain after harvest. In this study, fresh L. brownii bulbs were placed in the dark at 25, 4, and −20 °C and under light at 25 °C from 0 to 30 days; the chemical compositions were analyzed by ultraviolet spectrophotometry (UV) and high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS). During the 30-day storage period, the browning degree increased over the storage time and with increasing temperature, but the contents of proteins and free amino acids decreased and were aggravated by light. The total polyphenol content increased until the 6th day at 25 °C (dark or light), but it did not significantly accumulate at −20 or 4 °C. The reducing sugar content showed a dynamic balance, but the total polysaccharide content decreased constantly in the four storage conditions. The polyphenol oxidase (PPO) activity increased with storage time and increasing temperature, while it was inhibited by light. The increase rates of malondialdehyde (MDA) content at −20 °C and light (25 °C) were higher than those at 4 and 25 °C. In addition, 12 secondary metabolites were identified, most of which accumulated during the storage period, for example, 1-O-feruloyl-3-O-β-D-glucopyranosylglycerol; 1,3-O-di-p-coumaroylglycerol; 1-O-feruloyl-3-O-p-coumaroylglycerol; and 1,2-O-diferuloylglycerol. The variations in nutrient levels had a low correlation with browning, but the variations in MDA, PPO, and secondary metabolite (phenolic acids) levels had a high correlation with browning. In conclusion, fresh L. brownii bulbs should be stored at a low temperature (4 °C) and in dark condition, and browning bulbs are excellent materials for secondary metabolite utilization

Research of composition and photocatalytic property of carbon-doped Ti-O films prepared by R-MS using CO2 gas resource

In this paper, carbon-doped Ti-O films were prepared on silicon wafer and stainless steel by reaction magnetron sputtering using CO 2 as carbon and oxygen source. By changing the ratio of CO 2 /O 2 , a series of films with different composition can be obtained. X-ray photoelectron spectroscopy (XPS) was employed to analyze composition of as-prepared films. The result proved that carbon was doped into titanium successfully. Ultraviolet-visible (UV-Vis) spectrophotometer in the wavelength range of 250- 900 nm was used to record the absorbance of as-prepared film samples. The photocatalytic activities of as-prepared films were evaluated by measuring the decolorization rate of methyl orange under UV light irradiation. The results showed that as-prepared carbon-doped Ti-O films have fairly photocatalysis activity, which to be hoped to become candidate materials for photocatalyst. © 2013 Elsevier B.V. All rights reserved

Spatio-temporal development characteristics of major geohazards in Sichuan Province around "5·12" Wenchuan earthquake

The temporal and spatial development law of regional geohazards is the result of the joint action of internal and external geological forces, which are relatively stable within a large area. Therefore, the source, magnitude and occurrence time of earthquakes are the main factors affecting the temporal and spatial development law of regional geohazards. In order to study the impact of "5·12" Wenchuan earthquake on the spatial and temporal development of geohazards in Sichuan Province, based on the data of landslide, collapse, debris flow, earthquake and rainfall from 1998 to 2018, the spatial and temporal characteristics of major geohazards in Sichuan Province around the Wenchuan earthquake were analyzed by mathematical statistics and spatial analysis methods, The results show that: ① Activity in major disasters in Sichuan Province shows cycles, under normal circumstances, it presents a small cycle of about 3 years, after the earthquake geohazards increased year by year, to the peak of 4a, then decreased year by year; the impact is not obvious after 8 years; ② The relative intensity of major geohazards has little change after the earthquake, but the activity and intensity of geohazards are not corresponding before the earthquake. In the geomorphic division, the largest number of geohazards is in Sichuan Basin, and the most active is in Northwest Sichuan Plateau. Compared with that before the earthquake, the occurrence of geohazards in the quaternary system is higher than that in the hard rock area. The geohazards in the tectonic zones have obvious zoning characteristics. The earthquake intensity of the Yangtze quasi-platform is much greater than that of the Songpan-Ganzi geosynclinal fold system before and after the earthquake, but the disaster activity is obviously weaker than that of the Songpan-Ganzi geosynclinal fold system, and the basic structural units have similar characteristics

Nanocarbon-based catalytic ozonation for aqueous oxidation: Engineering defects for active sites and tunable reaction pathways

© 2020 American Chemical Society. All rights reserved. Catalytic ozonation relies on the direct oxidation by ozone (O3) and indirect oxidation by reactive oxygen species (ROS) produced from activated ozone molecules, and the technique has been recognized as one of the most promising remediation technologies in water decontamination. Functional nanocarbon materials have been extensively exploited as heterogeneous catalysts to drive catalytic ozonation because of the environmental-benign process, easy applicability, and high efficiency. Nevertheless, the bottlenecks in the processes are the economical production of high-performance and robust carbocatalysts and the debatable oxidation regimes. Different active sites have been suggested in engineered nanocarbons, and the corresponding mechanisms of the carbocatalytic ozonation are ambiguous including the evolution of various ROS, occurrence of radical and nonradical reaction pathways, selectivity toward organics, and tunable oxidation capacity. In this Review, we will showcase the roadmap of the development of reaction-oriented carbocatalysts and clarify the arguments in the mechanisms of the intrinsic active sites, identification of ROS, reaction intermediates, and oxidation pathways in carbocatalytic ozonation. We will provide critical comments and innovative strategies on the mechanistic investigations in carbon-based ozonation from the molecular level (electronic structures) to macroscale (kinetics), by deliberate radical screening/capture techniques, advanced characterizations and in situ analysis, and theoretical computations. More importantly, the critical issues and future directions will be proposed in the rational material/system design, mechanistic exploration, and the implementation of this powerful technology in catalytic oxidation and real wastewater treatment

Synthesis of magnetic carbon supported manganese catalysts for phenol oxidation by activation of peroxymonosulfate

Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe3O4/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as the precursor of manganese oxide. The Mn/MCS catalysts were characterized by a variety of characterization techniques and the catalytic performances of Fe3O4/C/Mn nanoparticles were tested in activation of peroxymonosulfate to produce reactive radicals for phenol degradation in aqueous solutions. It was found that Fe3O4/C/Mn catalysts can be well dispersed and easily separated from the aqueous solutions by an external magnetic field. Kinetic analysis showed that phenol degradation on Fe3O4/C/Mn catalysts follows the first order kinetics. The peroxymonosulfate activation mechanism by Fe3O4/C/Mn catalysts for phenol degradation was then discussed

Hierarchical shape-controlled mixed-valence calcium manganites for catalytic ozonation of aqueous phenolic compounds

Catalytic ozonation has attracted intensive attention due to its efficient degradation of various organic pollutants in water. The key to a practical application is the discovery of highly effective catalysts. This study, for the first time, reports excellent performances of porous mixed-valence calcium manganite (CaMn3O6 and CaMn4O8) microspheres made of 1D nanorods in the catalytic ozonation of 4-nitrophenol. The CaMn3O6 and CaMn4O8 showed much higher activities and stabilities than manganese oxides. From a variety of advanced characterizations, the mechanism of surface catalysis was discussed in detail. Quenching reagents and electron paramagnetic resonance (EPR) spectroscopy were applied to probe the dominant reactive species in the catalytic ozonation over the calcium manganites. It was found that superoxide radicals and singlet oxygen rather than hydroxyl radicals contributed to the degradation and mineralization of 4-nitrophenol. Moreover, the effects of electron-withdrawing groups (EWG) and electron-donating groups (EDG) in the phenolic compounds on the ozonation/catalytic ozonation over the calcium manganites were investigated using phenol, p-cresol and p-chlorophenol as target pollutants