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The dispersion of oil droplets near ocean surface is important for evaluating the impact to the environment. Under breaking wave conditions, the surface oil experiences mainly two processes: the generation of oil droplets at/near the water surface, and the transport of oil droplets due to ocean dynamics. We investigated the vertical behavior by incorporating the transport equation and the VDROP model. The transport equation adopted the ocean dynamics by K-profile parameterization (KPP) and the impact of additional turbulence by imposing the energy dissipation rate on the ocean surface. The oil droplet distribution was obtained, and the entrained distribution and entrainment rate was computed. The results shows that although the entrained distribution and the entrainment rate shares certain consistency with previous studies, divergences are also noticed. Accordingly, the model that describes the physics should be adopted to avoid incorrect qualification of the oil concentration dispersed in the ocean.

The use of dispersants can be an effective response tool for large offshore spills by applying dispersants on unemulsified slicks and treating as much oil as possible before it becomes too viscous. Assessing the dispersibility of an oil slick under actual environmental conditions is an important step in spill response decision-making. This research seeks to develop a new field kit that is quick and reliable and could be used by spill response personnel without scientific training. The resulting Dispersibility Assessment Kit (DAK) incorporates an automated mixing unit to standardize the applied energy, thereby eliminating the variability in “hand mixing” that is used in other dispersant field kits. The automated mixing energy was studied to determine the optimal mixing regime that correlates with ocean conditions and was incorporated in the DAK protocol. The DAK was validated against 14 oils and emulsions and was successfully tested by response personnel during at-sea demonstration.

The rapid development of high-speed railways has been tempered by various technical challenges. As more high-speed lines carrying more high-speed trains have opened in China, abnormal train noise has become an intermittent problem, affecting the quality of high-speed trains and the subjective comfort of passengers and crew. To mitigate the abnormal noise in the conductor room of a high-speed train, this paper proposes a method for evaluating and optimizing the sound quality (SQ) inside a high-speed train. First, the vibrational noise in the train was tested and analyzed under passenger-carrying operating conditions. Second, the SQ was objectively evaluated by quantifying the interior noise with one traditional physical acoustic parameter and six psychoacoustic parameters. In a statistical analysis of a subjective listening questionnaire, the low-frequency noise was best described by a verbal expression (the Dichen descriptor in Chinese), which serves as an evaluation index in jury tests. A subjective jury (30 participants) scored the values of various sound samples. Although the A-weighted sound pressure level (A-W SPL) in the conductor room was relatively small, it was perceived as extremely irritating. The auditory perception of the human ear was not objectively described by the traditional A-W SPL, but was quantified by the psychoacoustic parameter evaluation. In a correlation analysis of the subjective and objective evaluations, the correlation coefficient between tonality and the Dichen sensation was 0.983. The tonality is the key parameter of perceived SQ in high-speed trains. Therefore, an objective quantitative model of the subjective Dichen sensation was established through multiple linear regression theory with tonality as a variable. To determine the source of the discomforting noise, the vibro-acoustic characteristics in the conductor room were analyzed and a finite element analysis of the end wall was performed. The abnormal noise was traced to a high-intensity 40-Hz pure tone caused by an externally sourced structural modal excitation near the end wall. Based on hybrid finite element–statistical energy analysis, a vibro-acoustic radiation simulation model of the end wall was established. After optimizing the end-wall structure, the SQ in the high-speed train was significantly improved. The optimization effect was verified in a noise test conducted in the interior of a real high-speed train, and in a vibro-acoustic radiation simulation model. Our results can guide the evaluation and optimization of SQ in high-speed trains.

Injectable polysaccharide-based hydrogels are widely employed as drug delivery and tissue engineering materials due to the promising biocompatibility and biodegradability, while the mechanical property of polysaccharide hydrogels still requires to be enhanced much for further applications. In the present work, a family of injectable nanocomposite hydrogels were prepared for the first time through the Schiff base reaction between cationic octa (γ-chloroammoniumpropyl) silsesquioxane (OCAPS), chitosan (CS), and oxidized hydroxypropyl cellulose (HPC). It was found that OCAPS dispersed well in the hydrogels and inhibited the crystallization of CS and HPC, and the resulted nanocomposite hydrogels response pH values by reversible sol-gel transitions, namely as the pH value was less than 4.2, the hydrogels were low viscous solutions; while gelled again in mild and basic conditions. The gelation time of the hydrogels shrank from 80 to 49 s, and the swelling ratio increases from 3.7 to 6.6, along with the increase of OCAPS feed ratio gradually. The incorporation of OCAPS into the system also enhanced the mechanical property of the hydrogels. Compared with the controllable hydrogel without OCAPS, which failed to remain a certain shape for a long time, the nanocomposite hydrogels exhibited an outstanding compression property, and 68.4% of stain, 4.1 kPa of modulus, 97.9 kPa of strength when 40.0 wt% OCAPS was loaded. The rheological investigations suggested that the hydrogels possessed a very stable network, hence a self-healing property. Moreover, the result of Bovine serum albumin (BSA) load and release experiments demonstrated much improved drug load efficiency and cumulative drug release percentage of the nanocomposite hydrogels; the in-vitro degradation and cytotoxicity tests exhibited perfect biodegradability and biocompatibility of the hydrogels. All of these results demonstrate that the OCAPS and polysaccharides based hydrogels endow sound applications in drug carrier and tissue engineering materials.

Road traffic accidents resulting in group deaths and injuries are often related to coach drivers' inappropriate operations and behaviors. Thus, the evaluation of coach drivers' fitness to drive is an important measure for improving the safety of public transportation. Previous related research focused on drivers' age and health condition. Comprehensive studies about commercial drivers' cognitive capacities are limited. This study developed a toolkit consisting of nine cognition measurements across driver perception/sensation, attention, and reaction. A total of 1413 licensed coach drivers in Jiangsu Province, China were investigated and tested. Results indicated that drivers with accident history within three years performed overwhelmingly worse (p

Matrix dissolved oxygen (DO) levels, organic pollutants and nitrogen removal performances in subsurface wastewater infiltration systems (SWISs) with and without intermittent aeration operated under different organic pollutant loadings were investigated. The intermittent aeration strategy not only significantly increased removal rates of organic pollutants and NH4+-N, but also successfully created aerobic conditions in the depth of 50 cm and did not change anoxic or anaerobic conditions in the depth of 80 and 110 cm resulting in high TN removal. Increasing organic pollutant loading did not affect the removal of organic pollutants and nitrogen in intermittent aerated SWISs. High removal rates of COD (95.68 ± 0.21%–98.41 ± 0.23%), NH4+-N (93.77 ± 0.39%–98.06 ± 0.16%) and TN (84.48 ± 0.57%–94.02 ± 0.25%) were obtained simultaneously in intermittent aerated SWISs for the organic pollutant loading from 7.4 to 29.1 g COD/(m2 d), and significantly higher than non-aerated SWISs. Intermittent aeration boosted the growth and reproduction of nitrifying bacteria and denitrifying bacteria. In the depth of 80 and 110 cm, nitrate reductase (NR) and nitrite reductase (NIR) activities with intermittent aeration were higher than that without aeration. The results suggest that intermittent aeration was a reliable option to achieve high nitrogen removal in SWISs, especially under high organic pollutant loading.

A novel DNA-modified nanocomposite of three-dimensional reduced graphene oxide and chitosan particles (CS@3D-rGO@DNA) was prepared by one-step method and used as a new electrochemical biosensing strategy to detect Hg 2+ in drinking water. This biosensor was fabricated by the chemical coordination of T-Hg 2+ -T between the T-rich oligonucleotide strands contained in the as-prepared CS@3D-rGO@DNA nanocomposite and Hg 2+ , thereby varying the electrochemical signals. The developed electrochemical biosensor exhibited high sensitivity toward the determination of Hg 2+ with a low detection limit of 0.016 nM, ranging from 0.1 nM to 10 nM. This novel biosensor also showed high selectivity, good stability, and repeatability. Hence, this proposed CS@3D-rGO@DNA-based electrochemical strategy is feasible and may offer a simple, rapid, cost-effective, highly selective, and sensitive method for Hg 2+ quantification.

The meso-structure mineral composition and fracture mechanism of uniaxial compressed mudstone samples at high temperature were analyzed by XRD and scanning electron microscopy. The effect of temperature on mudstone composition and fracture mechanism were studied from a meso-structural perspective, and the relationship between meso-structure and macro-mechanical characteristics at high temperature was revealed. The findings demonstrated that the fluctuation in diffraction intensity of kaolinite in the mudstone caused the fluctuation in its mechanical properties. The overall structure underwent a phase change around 600 °C, which led to the sudden change in the mechanical properties of mudstone samples. When the temperature reached 600 °C, the crystalline state worsened and kaolinite disappeared; however, some illite was produced, indicating that the chemical reaction of the structure and sudden drop of bearing capacity of the mudstone. Mudstone fracturing at high temperature involves mainly intergranular and transgranular fractures, which are typical in micro-brittle tensile failure. Considering the macro-fracture characteristics of mudstone, the results suggested that macro-fracture under external force corresponds to the meso-fracture. Keywords: Mudstone, Mineral composition, SEM, Meso-fracture, Macro-fracture

Colloidal hybrids comprise organic and inorganic components and are attracting considerable attention in the literature. Recently, we reported hybrid anisotropic microsheets that formed thermoresponsive gels in polymer solutions [Liu et al., Langmuir, 25, 490, 2009]. Here, we investigate the composition and properties of these hybrid colloids themselves in detail for the first time. Three different cationic PNIPAm (N-isopropylacrylamide) graft copolymers and two inorganic nanoparticle types (laponite and Ludox silica) were used to prepare a range of hybrids. Anisotropic microsheets only formed when laponite particles were added to the copolymer implying directed self-assembly. Aqueous dispersions of the microsheets spontaneously formed gels at room temperature and these gels were thermoresponsive. They represent a new class of gel forming colloid and are termed thermoresponsive gel forming hybrids. The compositions of the hybrids were determined from thermogravimetric analysis and those that gave gel forming behaviour identified. Variable-temperature rheology experiments showed that the elasticity of the gels increased linearly with temperature. The reversibility of the thermally-triggered changes in gel elasticity was investigated. The concentration dependence of the rheology data was well described by elastic percolation scaling theory and the data could be collapsed onto a master curve. The concentration exponent for the elastic modulus was 2.5. The strong attractive interactions that exist between the dispersed gel forming hybrids was demonstrated by the formation of stable thermoresponsive hybrid hydrogels through casting of hybrid dispersions.

Probably because of material and fabrication limitations, most previously developed hollow fibers were lack of high performance for pervaporation dehydration applications. In this paper, we have successfully developed integrally skinned BTDA-TDI/MDI (P84) co-polyimide hollow fibers for pervaporation dehydration of isopropanol (IPA), which have impressive flux and selectivity towards water. The effects of spinning conditions such as air gap distance, coagulation temperature, and dope/bore fluid flow rates on membrane formation, morphology and pervaporation performance have been determined. Even though spinning conditions affect membrane separation performance, it is found that silicone rubber coating and heat treatment play much more important roles on performance enhancement. Not only can the silicone rubber coating effectively seal the membrane defects, but also triple the selectivity because of its nature of high water permeability while its hydrophobic property does not dominate. A tremendous increase in separation factor/selectivity (20–100 times) is observed after a heat treatment at 300 ∘ C . The newly developed P84 hollow fibers after heat treatment have a flux of 883.5 g / m 2 h and a separation factor of 10 585 for dehydration of 85/15 (w/w) IPA/water mixture at 60 ∘ C .

The Dirichlet distribution is often used as a prior distribution for the parameters of a multinomial distribution. Because this distribution has support on the simplex 0⩽ x i ⩽1, ∑ x i =1, it does not serve as the prior for a correlated binomial distribution. We here present a bivariate beta distribution that has support on 0⩽ x i ⩽1, i =1,2. When expanded in a power series it is related to the hypergeometric function. This bivariate density is positively likelihood ratio dependent and hence is positive quadrant dependent.