High Water Resistance and Enhanced Mechanical Properties of Bio-Based Waterborne Polyurethane Enabled by in-situ Construction of Interpenetrating Polymer Network

In this study,acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization.The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly(acrylic acid)(WPU-PAA)dispersion and the films were systematically investigated.The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid,leading to enhancement of the mechanical properties and water resistance of WPU-PAA films.Notably,with the increase in content of acrylic acid,the tensile strength,Young’s modulus,and toughness of the WPU-PAA-110 film increased by 3 times,and 8 times,and 2.4 times compared with WPU-PAA-80,respectively.The WPU-PAA-100 film showed the best water resistance,and the water absorption rate at 96 h was only 3.27%.This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.

Double Z-Scheme g-C_(3)N_(4)/BiOI/CdS heterojunction with I_(3)^(-)/I^(-) pairs for enhanced visible light photocatalytic performance

The g-C_(3)N_(4)/BiOI/CdS double Z-scheme heterojunction photocatalyst with I_(3)^(-)/I^(-) redox pairs is prepared using simple calcination,solvothermal,and solution chemical deposition methods.The photocatalyst comprised mesoporous,thin g-C_(3)N_(4) nanosheets loaded on flower-like microspheres of BiOI with CdS quantum dots.The g-C_(3)N_(4)/BiOI/CdS double Z-scheme heterojunction has abundant active sites and in situ redox I_(3)^(-)/I^(-) mediators and shows quantum size effects,which are all conducive to enhancing the separation of photoinduced charges and increasing the photocatalytic degradation efficiency for bisphenol A,a model pollutant.Specifically,the heterojunction photocatalyst achieves a photocatalytic degradation efficiency for bisphenol A of 98.62%in 120 min and photocatalytic hydrogen production of 863.44 mmol h^(-1) g^(-1) on exposure to visible light.The excellent visible-light photocatalytic performance is as a result of the Z-scheme heterojunction,which extends absorption to the visible light region,as well as the I_(3)^(-)/I^(-) pairs,which accelerate photoinduced charge carrier transfer and separation,thus dramatically boosting the photocatalytic performance.In addition,the key role of the charge transfer across the indirect Z-scheme heterojunction has been elucidated and the transfer mechanism is confirmed based on the detection of intermediate I_(3)^(-)ions.Thus,this study provides guidelines for the design of indirect Z-scheme heterojunction photocatalysts.

A Fine Investigation on Geological Conditions for Oil Accumulation in the Paleogene Intersalt Shale Series in the Qianjiang Depression

This study dealt with the rhythmic Qian 3410 of the intersalt shale series in the Qianjiang Depression,in which the geological condition for oil accumulation in the rhythmic shale was investigated by using the basic drilling,core and well logging data,as well as data obtained from the thin section identification,SEM,mercury injection,X-ray diffraction and rock freezing heat analyses.The study result indicated that:1)the intersalt shale series are characterized by TOC in a range of 0.35%-6.38%(averaging 3.19%),Types I and II1 organic matter,and from immature to mature oil,indicative of a potential for generating a great volume of immature oil;2)in the target layer,mineral compositions are complicated,which can divide into argillaceous dolomite facies,argillaceous limestone facies,dolomitic mudstone facies,and calcium-mirabilite-filling dolomitic mudstone facies;and 3)of them,the argillaceous dolomite facies is the most contributory,with reservoir spaces consisting of intergranular pores as dominant,as well as rare dissolution pores and seams.It is characterized by high organic abundance(4.23%-6.38%),high content of brittle mineral(50%-71%),low content of clay mineral(18%-33%),high porosity(10.8%-26.3%)and good oil-bearing properties(S1 distributed in 3.48-5.64 mg/g,and S1/TOC value in a range of 348-564 oil mg/g).Therefore,the argillaceous dolomite facies was considered the key target series to be explored for the intersalt shale oil in the study area in the coming days.

Effect of surface roughness on the aerodynamic performance of turbine blade cascade

The effect of surface roughness on the boundary development and loss behavior of turbine blades is investigated with different Reynolds numbers in this paper.The result shows that the velocity profile in boundary layer is plumper on rough surface than on smooth blade.The aerodynamic loss is lowered at low Reynolds number,but becomes significantly large at high Reynolds number.The total pressure loss coefficient of cascade can reach a top increase of 129%for rougher blades comparing with smooth blades at Re=300000.

Inhibitive effects of three compositae plants on Microcystis aeruginosa

Based on common phenomena of biochemical interaction between plants and microorganisms,the inhibitive effects of three common terrestrial compositae plants,namely Artemisia lavandulaefolia DC.,Conyza canadensis(L.)Cronq.,and Kalimeris indica(L.)Sch.-Bip.on the blue algae Microcystis aeruginosa was studied.Live compositae plants are co-cultivated with algae in two different inoculation doses for 10 days in 5-pools incubators,in order to exclude the influence of bacteria and nutrients.The results show that Artemisia lavandulaefolia DC has the most inhibitive potential among the three plants as evidenced by the most drastic decrease in optical density(OD680)of the algae.The inhibition rate is 93.3%(with initial inoculation dose of 2.0×10^(6) Cells/mL)and 89.3%(with initial inoculation dose of 4.0×10^(6) Cells/mL)respectively on the 10th day of cultivation.The average inhibition rate during the later half of the experiment is 0.76(with initial inoculation dose of 2.0×10^(6) Cells/mL)and 0.71(with initial inoculation dose of 4.0×10^(6) Cells/mL),respectively.Logistic model analysis shows that compositae plants such as A.lavandulaefolia DC.causes the reduction of the habitat’s carrying capacity of algae.ANOVA analysis is used to determine the similarity and differences between every experimental group and an average inhibitive rate model is used to evaluate the inhibition effects.The results show that A.lavandulaefolia DC.,which grow well in the aquatic environment,may have a great potential in controlling algae bloom in eutrophic water.

Conjugate heat transfer investigation of cooled turbine using the preconditioned density-based algorithm

The preconditioned density-based conjugate heat transfer(CHT)algorithm was used to investigate the heat transfer characteristics of a cooled turbine vane.Fluid domain provided boundary heat flux for solid domain and obtained boundary temperature from it for the coupling strategy.The governing equations were solved by the preconditioned density-based finite-volume method,with preconditioning matrix,improved Abu-Gharmam Shaw(AGS)transition model,matrix dissipation scheme and four kinds of turbulence models.The grid system is multi-block structured grids for fluid domain and unstructured grids for solid domain,with full-matched grids at the fluid-solid interfaces.The effects of turbulence model,outlet Mach number,outlet Reynolds number,inlet turbulence intensity and the temperature ratio of blade surface/gas on the local heat transfer performance were studied.Results indicate that the k-o shear-stress transport(SST)and AGS model can predict the conjugate heat transfer better than others.The Mach number and Reynolds number have relatively obvious influences on the heat transfer,while the turbulence intensity and temperature ratio only have slight influences.Comparisons with experimental data demonstrate the applicability and accuracy of the numerical algorithm.

Air pollution and inhalation exposure to particulate matter of different sizes in rural households using improved stoves in central China

Household air pollution is considered to be among the top environmental risks in China.To examine the performance of improved stoves for reduction of indoor particulate matter（PM） emission and exposure in rural households, individual inhalation exposure to size-resolved PM was investigated using personal portable samplers carried by residents using wood gasifier stoves or improved coal stoves in a rural county in Central China.Concentrations of PM with different sizes in stationary indoor and outdoor air were also monitored at paired sites. The stationary concentrations of size-resolved PM in indoor air were greater than those in outdoor air, especially finer particles PM0.25. The daily averaged exposure concentrations of PM0.25, PM1.0, PM2.5 and total suspended particle for all the surveyed residents were 74.4 ± 41.1, 159.3 ± 74.3, 176.7 ± 78.1 and 217.9 ± 78.1 μg/m3,respectively. Even using the improved stoves, the individual exposure to indoor PM far exceeded the air quality guideline by WHO at 25 μg/m3. Submicron particles PM1.0 were the dominant PM fraction for personal exposure and indoor and outdoor air. Personal exposure exhibited a closer correlation with indoor PM concentrations than that for outdoor concentrations. Both inhalation exposure and indoor air PM concentrations in the rural households with gasifier firewood stoves were evidently lower than the reported results using traditional firewood stoves. However, local governments in the studied rural areas should exercise caution when widely and hastily promoting gasifier firewood stoves in place of improved coal stoves, due to the higher PM levels in indoor and outdoor air and personal inhaled exposure.

Impact of Stagger Angle Nonuniformity on Turbine Aerodynamic Performance

The assembling error may lead to variation in stagger angles,which would affect the aerodynamic performance of the turbine.To investigate this underlying effect,two parallel numerical experiments on two turbines with the same profile,but uniform and nonuniform vane stagger angle respectively,were conducted in both steady and unsteady methods.The results indicate that certain changes in the detailed flow field of the turbine occur when the stagger angles are nonuniform,further,the blade loading distribution of the vane and rotor become markedly different from that in uniform vane stagger angle situation.Then these consequences caused by nonuniformity mentioned above enhance the unsteadiness of the flow,finally,the aerodynamic performance changes dramatically.It also shows that,compared with steady simulation,the unsteady numerical simulation is necessary in this investigation.