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Pollutants generally exist as mixtures in the environment. Their cumulative toxicity and toxicity interactions are potential risks. Therefore, this study aimed to examine the variation of joint toxicity of a multi-component mixture system, which consisted of six common quaternary ammonium salt surfactants in the environment, on Vibrio qinghaiensis sp.-Q67 (Q67). Vibrio qinghaiensis sp. -Q67 (Vqin-Q67) is a freshwater luminescent bacterium that continuously emits blue-green light (485 nm). The bacterium has been widely used for detecting toxic contaminants. In the mixture system, the luminescent toxicity of each component of the mixture to Q67 was determined by the microplate toxicity analysis method, and the toxicity interaction of the mixture was determined by the toxicity unit method (TU). The combined toxicity of the mixture system was investigated from four aspects, including the number of components, key components, concentration (toxicity) ratio, and exposure time. The results showed that the combined toxic effect of the same mixture system tends to be an additive effect with the increase of the number of components. The combined toxicity of the mixture system was close to that of the key components. Antagonism was presented in the equal toxicity mixture, while synergism was presented in the non-equal toxicity mixture. The combined toxic effect of the multi-component mixture system was not only related to the concentration of the pollutant but also related to the exposure time of the pollutant.

The rheological behavior of Polyethylene (PE) modified bitumen is investigated. It is found that a rheological plateau under high temperature presented on the curve of storage modulus (G*) variation with temperature. By the addition of little wax, the rutting resistance of bitumen/PE blend can be further improved. Moreover, the wax incorporation into bitumen/PE can significantly decrease the starting temperature of rheological plateau to accommodate the actual service temperature of bituminous pavement, making a potential application of PE/wax modified bitumen in pavement engineering. The reason for this rheological property enhancement by wax is explored in terms of phase separation structure and thermal behavior of bitumen/PE blends. Main focus is put on the relationship between PE crystallinity and rheological behavior.

BiFeO3 nanoparticles were prepared via a polyacrylamide gel route. BiFeO3-graphene nanocomposites were fabricated by mixing BiFeO3 nanoparticles and graphene into absolute ethanol solution followed by thermal drying. The TEM observation demonstrates that the BiFeO3 nanoparticles are well anchored onto graphene sheets. The photocatalytic activities of the as-prepared samples were evaluated by the degradation of methyl orange (MO) under simulated sunlight irradiation. Compared to bare BiFeO3 nanoparticles, BiFeO3-graphene nanocomposites exhibit enhanced photocatalytic activity. The outstanding photocatalytic performance is mainly ascribed to the efficient transfer of photogenerated electrons from BiFeO3 to graphene, thus leading to an increased availability of h+ for the photocatalytic reaction. In addition, hydroxyl (·OH) radicals were detected by the photoluminescence technique using terephthalic acid as a probe molecule and are found to be produced on the irradiated BiFeO3 and BiFeO3-graphene nanocomposites; in particular, an enhanced yield is observed for the latter.

A three dimensional finite element model (FEFLOW) has been used for regional ground water flow modeling of Mihuaishun plain located in the south of Beijing, China. The numerical groundwater flow model is developed considering recharge components (precipitation infiltration, river leakage, and irrigation return flow). GIS interface is created for each source of recharge. Hydraulic conductivities and storage coefficient have been calibrated by the steady state model using the recorded data from 2007 to 2009. The model results is useful to identify the aquifer characteristics and to analyze the groundwater dynamics. The groundwater level monitoring network will be improved by analyzing groundwater levels. The future development scenarios are proposed to predict the trend changes of groundwater levels.

The large-scale preparation of disorderly CNTs with a length larger than 3 mm using CVD method were aligned in polymer monomer airflow fields in a quartz tube with an internal diameter of 200 μm and a length of 1.5 m. The airflow aligned CNTs at the output end of the pipe connects to a copper nozzle with an electrostatic field of applied voltage 5x105 V m and space length of 0.03 m, which were further realigned using via electrostatic spinning. End to end spray into the high speed rotor twisted single-stranded carbon nanotubes threads via rotor spinning technology. The essential component of this technique was the use of carbon nanotubes at a high rotory speed (200000 r min) combined with the double twisting of filaments that were twisted together to increase the radial friction of the entire section. SEM micrography showed that carbon nanotube thread has a uniform diameter of approximately 200 μm. Its tensile strength was tested up to 2.7 Gpa, with a length of several meters.

Rheological behavior of styrene-butadiene-styrene (SBS) modified bitumen with the presence of micro glass bead (GB) is investigated. It is found that either the GB fraction or size can influence the rheological property of bitumen/SBS/GB blends. Phase separation structures in all the modified bitumen systems keep a droplet-matrix type due to the sizeable compositional asymmetry between SBS-rich phase and bitumen-rich phase. The difference in the interfacial area fraction, obtained by Image J analysis reflects the effect of GB size on the rheological property. Further study on the rheology-structure correlation is put special attention on bee structure (catana phase) measured by AFM. It is found that the ratio of specific amplitude to the wavelength (Α0/λ0) of a bee-like structure may be a valid indicator of stiffness for the modified bitumen concerning the effect of GB size difference on the rheological property. When the chemical composition is the same, the lower value of Α0/λ0 indicates the modified bitumen with higher stiffness.

In this paper, we aimed at probing the ferromagnetism properties of Pd and Pd-Cu- codoped supercell BN based on the first-principles methods. The formation energy, lattice constants, energy band structures, spin density of state, energy difference between ferromagnetism (FM) and autiferromagnetism (AFM) orderings were calculated. Formation energy calculations showed that Pd atom tended to replace B atom in the supercell. Pd-doped BN exhibited a half-metallic ferromagnetic. And the ferromagnetism arised form the strong hybridization between the Pd4d and N2p state. Pd-Cu-codoped BN also displayed a half-metallic ferromagnetic. The incorporation of Pd and Pd-Cu induced some impurity energy differences between FM and AFM orderings. It also showed that FM state was the ground state, and room temperature ferromagnetism may be expected. These results pointed out the possibility of fabricating BN based on dilute magnetic semiconductors (DMS) by doping with Pd and Pd-Cu.

In this study, a polyacrylamide gel route was introduced to synthesize TiO 2 nanoparticles. The influence of synthesis conditions on the properties of products was investigated. It is found that the samples prepared at the calcination temperature of 400 °C crystallize majorly in the anatase phase with a minor rutile phase. The second rutile phase has a dependence on the chelating agent, which is formed more readily when using acetic acid as the chelating agent. The introduction of acrylamide and glucose to the precursor solution shows the capability of improving the particle morphology, and the resulted particles are uniformly shaped like spheres. The photocatalytic activity of the prepared TiO 2 samples was evaluated by the degradation of acid orange 7 under 254 nm ultraviolet irradiation, revealing that they exhibit a good photocatalytic activity. Ethanol was used as a · OH scavenger to investigate its effect on the photocatalytic efficiency as well as the · OH radical yields. Based on the experimental results, · OH radical is suggested to be the dominant active species responsible for the dye degradation.

We have investigated the effects of O 2 , ethanol, and KI on the photocatalytic efficiency of Bi 2 Fe 4 O 9 nanoparticles towards the degradation of methylene blue (MB). It is observed that O 2 has a negligible effect on the photocatalytic degradation rate of the dye, whereas ethanol and KI exhibit a strong suppression of the dye degradation, with a stronger effect observed for the latter. Hydroxyl radicals are shown, by the photoluminescence technique using coumarin as a probe molecule, to be produced on the irradiated Bi 2 Fe 4 O 9 , and are scavenged on addition of ethanol and KI. The mechanisms involved are discussed in detail. Based on the experimental results, hydroxyl radicals and photogenerated holes are suggested to be the two main active species in the photocatalytic degradation of MB by Bi 2 Fe 4 O 9 nanoparticles.

Objective: We aimed to evaluate the current status of sexual maturation of Chinese children, to examine the association between obesity and early sexual maturation in boys and compare it with girls and to test the hypothesis that the associations differ by gender. Study Design: Cross-sectional study. Subjects: A representative sample involving 9812 boys and 8895 girls aged 6–18 years who participated in the Chinese Children and Adolescent Metabolic Syndrome Epidemiologic Study (July 2009– July 2010) were surveyed. Methods: All subjects had complete anthropometry and sexual maturation data. Subjects who reached Tanner stage 2 or more (5601 boys and 6538 girls) were divided into tertiles based on the timing of sexual maturation. The subjects in the earliest tertile were included into the early-maturing group, and the middle tertile and the latest tertile into the not early-maturing group. Overweight was defined as a body mass index (BMI) ⩾85th percentile and obesity ⩾95th percentile. Logistic regression analysis was used to test how early maturation affected the risk of overweight. Multiple linear regression was used to examine the association between fatness (BMI Z- score) and sexual maturation. Results: Slightly more boys were obese than girls ( P <0.01). The median age for girls of the Tanner stage 2 was 9.69 years, and for boys of Tanner stage 2 was 11.25 years. BMI Z -score were higher ( P <0.01) in both early-maturing girls and boys, compared with the non-early maturers, respectively. Early sexual maturation was positively associated with obesity in both girls and boys. With covariates adjusted and using non-early maturing as the reference group, odds ratios for combined overweight were 1.48 for boys and 2.64 for girls, and for obesities were 1.61 for boys and 3.49 for girls, respectively. Conclusion: Obesity is positively associated with sexual maturation in both boys and girls, and the association does not differ by gender, but the association is stronger in girls than in boys.