The tungsten trioxide(WO3) thin films were firstly prepared by spin-coating-pyrolysis methods using the ammonium metatungstate((NH4)6H2W12O40)DMF/water solution, and successfully applied as the efficient compact...The tungsten trioxide(WO3) thin films were firstly prepared by spin-coating-pyrolysis methods using the ammonium metatungstate((NH4)6H2W12O40)DMF/water solution, and successfully applied as the efficient compact layers for the planar perovskite solar cells. The influence of the WO3 film thickness and the rinsing treatment of CH_3NH_3 PbI_3 thin film with isopropanol on the photovoltaic performance of the corresponding perovskite solar cells was systematically investigated. The results revealed that the perovskite solar cell with a 62 nm thick WO3 compact layer achieved a photoelectric conversion efficiency of 5.72%, with a short circuit photocurrent density of 17.39 mA/cm^2, an open circuit voltage of 0.58 V and a fill factor of 0.57. The photoelectric conversion efficiency was improved from 5.72% to 7.04% by the isopropanol rinsing treatment.展开更多
For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings difficulty to application and misleads the interpretation of relevant experiments. Here, we report a quan...For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings difficulty to application and misleads the interpretation of relevant experiments. Here, we report a quantification scheme for the freezable bound water based on the water-content dependence of glass transition temperature, by which also the concentration range for the solutions that may undergo recrystallization finds a clear definition. Furthermore, we find that depending on the amount of the freezable bound water, different temperature protocols should be devised to achieve a complete recrystallization. Our results may be helpful for understanding the dynamics of supercooled aqueous solutions and for improving their manipulation in various industries.展开更多
Silicate perovskites((Mg, Fe)SiO 3 and CaS iO 3) are believed to be the major constituent minerals in the lower mantle. The phase relation, solid solution, spin state of iron and water solubility related to the lo...Silicate perovskites((Mg, Fe)SiO 3 and CaS iO 3) are believed to be the major constituent minerals in the lower mantle. The phase relation, solid solution, spin state of iron and water solubility related to the lower mantle perovskite are of great effect on the geodynamics of the Earth's interior and on ore mineralization. Previous studies indicate that a large amount of iron coupled with aluminum can incorporate into magnesium perovskite, but this is discordant with the disproportionation of(Mg,Fe)SiO 3 perovskite into iron-free MgS i O3 perovskite and hexagonal phase(Mg0.6Fe0.4)SiO 3 in the Earth's lower mantle. MnS iO 3 is the first chemical component confirmed to form wide range solid solution with Ca SiO 3 perovskite and complete solid solution with MgS i O3 perovskite at the P-T conditions in the lower mantle, and addition of Mn Si O3 will strongly affects the mutual solubility between Mg Si O3 and CaS iO 3. The spin state of iron is deeply depends on the site occupation of the Fe3+or Fe2+, the synthesis and the annealing conditions of the sample. It seems that the spin state of Fe2+ in the lower mantle perovskite can be settled as high spin, however, the existence of intermediate spin or low spin state of Fe2+ in perovskite has not been clarified. Moreover, different results have also been reported for the spin state of Fe3+ in perovskite. The water solubility of the lower mantle perovskite is related with its composition. In pure Mg SiO 3 perovskite, only less than 500 ppm water was reported. Al–Mg Si O3 perovskite or Al–Fe–MgS iO 3 perovskite in the lower mantle accommodates water of 1100 to 1800 ppm. Further experiments are necessary to clarify the detailed conditions for perovskite solid solution, to reliably analyze the valence and spin states of iron in the coexisting iron-bearing phases, and to compare the water solubility of different phases at different layers for deeply understanding the geodynamics of the Earth's interior and ore mineralization.展开更多
The waste water system generated in the process of production of cuprous chloride was studied.The existing forms of copper in the system and the influence of temperature and pH on the existing forms of copper ion were...The waste water system generated in the process of production of cuprous chloride was studied.The existing forms of copper in the system and the influence of temperature and pH on the existing forms of copper ion were analyzed and determined through calculating the coefficients of copper complex distribution.In the waste water system,the main forms of copper are CuSO4, Cu2 +,CuCl + ,CuCl, 2-and2- 3 CuCl.Temperature has little influence on the distribution coefficient of Cu(Ⅱ),but has significant influence on distribution coefficient of Cu(Ⅰ).With the increase of temperature,the distribution coefficient ofCuCl, 2-increases significantly while the distribution coefficient of2- 3 CuCl decreases.The pH has nearly no influence on the distribution coefficients of various Cu(Ⅰ)-compounds,but has sizable influence on the distribution coefficients of Cu(Ⅱ)-compounds.With the increase of pH,the distribution coefficient of CuSO4(aq)increases while the distribution coefficients of Cu 2+ and CuCl + decrease.According to these results,the anion resin of 201×7 OH-and the cation resin of 732 Na were chosen to dispose the waste water solution of cuprous chloride.Finally,97.9%copper in the waste water is recovered.展开更多
The paper presents a flow plasma reactor permitting modification of the properties of water/aqueous solutions by stochastic resonance amplification of vibrations of selected chemical species in water with electromagne...The paper presents a flow plasma reactor permitting modification of the properties of water/aqueous solutions by stochastic resonance amplification of vibrations of selected chemical species in water with electromagnetic noise generated during a plasma discharge. The main parameters characterizing the quality for super-pure water, tap water and water from the intake in Besko (Poland) before and after the process in the plasma reactor were presented for comparison. In addition, the <sup>17</sup>O NMR (the full width at half maximum) and electrospray ionization mass spectrometry (ESI MS) methods were used to determine differences in physicochemical parameters between the untreated and plasma-treated water. It has been established that the water subjected to plasma treatment shows much different gas absorption properties than the untreated water samples, as a function of temperature and pressure, in this paper we report exemplary data for CO<sub>2</sub>, oxygen and acetylene. The improved gas absorption properties of the plasma-treated water make it attractive for the use in industrial processes. It is worth pointing to a great capacity of the new reactor (4000 l/h), and low energy consumption (20 MJ/h) for the treatment of the above mentioned volume flow rate of water.展开更多
Structural properties of the pure water and halogen solutions at high temperatures and pressures are studied by using the molecular dynamics simulations and quantum molecular simulations. The related characters are ca...Structural properties of the pure water and halogen solutions at high temperatures and pressures are studied by using the molecular dynamics simulations and quantum molecular simulations. The related characters are calculated as functions of temperature and pressure. The results show that the hydrogen bonded networks become looser as temperature increases,with the collapse of the traditional tetrahedral structure. It is similar to the concentration-dependent collapse in the Na Cl solutions. However, adding other halogen elements has no further effects on the already weakly bonded water molecules.At the phase changing points, the process of hydration is evident for the bigger ions, so that the bigger the ion is, the smaller a cluster is formed.展开更多
A small amount of mineralizer MgO was added into Al2TiO5 synthesized from the sludge of aluminum factory to form Al(2-x)Mg(x+y)Ti(1-y)O(5-0.5x-y) solid solution and inhibit the decomposition of Al2TiO5 solid ...A small amount of mineralizer MgO was added into Al2TiO5 synthesized from the sludge of aluminum factory to form Al(2-x)Mg(x+y)Ti(1-y)O(5-0.5x-y) solid solution and inhibit the decomposition of Al2TiO5 solid solution. It increased the content of Al2TiO5 solid solution and improved the thermal stability of materials. In this work,XRD and SEM methods were adopted to characterize the crystalline structure and microstructure of each kind of sample. Rietveld Quantification method was used to determine the content of crystalline phases in each sample. Results show as follows: the optimal addition concentration of MgO was 2.0%,and the corresponding content of Al2TiO5 solid solution which displayed irregular bulk shape was 100%; the addition of mineralizer MgO could enhance the flexural strength and thermal stability of Al2TiO5 solid solution materials. The optimal addition concentration of MgO determined by performance analysis was 2.0%,and its corresponding retention rate of thermal-shock flexural strength was 86.4%. Structure analysis and performance analysis resulted in good accordance.展开更多
The intensive and inappropriate use of water, fertilizers and phytosanitary products is sources of water and soil pollution. It is thus necessary to improve the management of irrigation water in order to optimize its ...The intensive and inappropriate use of water, fertilizers and phytosanitary products is sources of water and soil pollution. It is thus necessary to improve the management of irrigation water in order to optimize its use and productivity, especially in regions where water resources are becoming increasingly scarce. The water flow and non-reactive solutes’ transport simulation under drip irrigation were carried out in a 3-layered soil profile distributed from top to bottom<em> i.e</em>., sandy, sandy-silty, silty-sandy-clay. The aim of this study was thus, to provide a good practice of water management associated with solutes’ application, in order to retain as much solute as possible in the root zone, which will increase the residence time of the solutes. Three treatments of water flux corresponding to 100% <em>ET</em><sub><em>c</em></sub>, 75% <em>ET</em><sub><em>c</em></sub>, 50% <em>ET</em><sub><em>c</em></sub>, combined with 100 mmol /L/ m<sup>2</sup> of NPK and 246 mmol/L/m<sup>2</sup> of urea applicable in two doses, were carried out over a period of 110 days corresponding to the duration of the cropping cycle for the intermediate variety of maize. The 100%<em> ET</em><sub><em>c</em></sub> and 75% <em>ET</em><sub><em>c</em></sub> treatments cause more loss of water and solutes, because of the sandy texture of the soil. However, a 50% <em>ET</em><sub><em>c</em></sub> water flux would reduce more water loss through drainage, and solutes’ loss due to leaching beyond the root zone, which would increase the residence time of solutes in the soil profile. Application tests of the NPK solute on different days before the 15<sup>th</sup> day after sowing were also carried out according to the technical itinerary for maize production in Burkina Faso, in order to find a favorable day for application of the solute. For the different dates of solute’s application, there was more loss of the solute as we approach the 15<sup>th</sup> day after sowing. To limit this loss and increase the residence time of the NPK solute, one could apply the solute without first supplying water, the day before and the day after the date of solute’ injection. Or, one could amend the soil with organic matter to improve its retention capacity of water, and the solutes’ residence time in the soil.展开更多
A newly developed approach for trace metal elements detection for aqueous samples analysis is presented in this paper. The idea of this approach is to improve ablation efficiency by transforming the liquid sample into...A newly developed approach for trace metal elements detection for aqueous samples analysis is presented in this paper. The idea of this approach is to improve ablation efficiency by transforming the liquid sample into a dense cloud of droplets using an ultrasonic nebulizer. The resulting droplets are then subjected to analysis by laser induced breakdown spectroscopy (LIBS). A purpose-built ultrasonic nebulizer assisted LIBS (UN-LIBS) system has been applied to the analysis of aqueous samples at trace levels of concentration. Experimental investigations of solution samples were carried out with various dissolved trace metal elements (Mn, Zn, Cu, Pb, Fe, Mg and Na) using this approach. The characteristics of UN-LIBS signal of the elements were investigated regarding the lifetime and S/B ratio and the calibration curves for trace metal elements analyses. The obtained LODs are comparable or much better than the LODS of the reported signal enhancement approaches when the laser pulse energy was as low as 30 mJ. The good linearity of calibration curves and the low LODs shows the potential ability of this method for metal elements analysis application. The density of the electrons was calculated by measuring the Stark width of the line of Ha. The possible mechanism of the LIBS signal enhancement of this approach was briefly discussed.展开更多
Long waves generated by a moving atmospheric pressure distribution, associated with a storm, in coastal region are investigated numerically. For simplicity the moving atmospheric pressure is assumed to be moving only ...Long waves generated by a moving atmospheric pressure distribution, associated with a storm, in coastal region are investigated numerically. For simplicity the moving atmospheric pressure is assumed to be moving only in the alongshore direction and the beach slope is assumed to be a constant in the on-offshore direction. By solving the linear shallow water equations we obtain numerical solutions for a wide range of physical parameters, including storm size (2a), storm speed (U), and beach slope (a). Based on the numerical results, it is determined that edge wave packets are generated if the storm speed is equal to or greater than the critical velocity, Ucr, which is defined as the phase speed of the fundamental edge wave mode whose wavelength is scaled by the width of the storm size. The length and the location of the positively moving edge wave packet is roughly Ut/2 〈 y 〈 Ut, where y is in the alongshore direction and t is the time. Once the edge wave packet is generated, the wavelength is the same as that of the fundamental edge wave mode corresponding to the storm speed and is independent of the storm size, which can, however, affect the wave amplitude. When the storm speed is less than the critical velocity, the primary surface signature is a depression directly correlated to the atmospheric pressure distribution.展开更多
In this paper, the effects of polymer additives and nozzle shape on the proper- ties of high pressure water jet discharging into the air are investigated by theory and experiments. Criteria of judging the jet quality ...In this paper, the effects of polymer additives and nozzle shape on the proper- ties of high pressure water jet discharging into the air are investigated by theory and experiments. Criteria of judging the jet quality are put forward. And, a method that can be used in analysing the fluid flow within the nozzle is developed. Then, the calculated results are compared with the experiments that we carried out; it is shown that the degree of agreement between the two is good. At last, the mechanism to improve on the jet quality with polymer additives is discussed.展开更多
In this study, an ultrasonic nebulizer unit was established to improve the quantitative analysis ability of laser-induced breakdown spectroscopy (LIBS) for liquid samples detection, using solutions of the heavy meta...In this study, an ultrasonic nebulizer unit was established to improve the quantitative analysis ability of laser-induced breakdown spectroscopy (LIBS) for liquid samples detection, using solutions of the heavy metal element Pb as an example. An analytical procedure was designed to guarantee the stability and repeatability of the LIBS signal. A series of experiments were carried out strictly according to the procedure. The experimental parameters were optimized based on studies of the pulse energy influence and temporal evolution of the emission features. The plasma temperature and electron density were calculated to confirm the LTE state of the plasma. Normalizing the intensities by background was demonstrated to be an appropriate method in this work. The linear range of this system for Pb analysis was confirmed over a concentration range of 0-4,150ppm by measuring 12 samples with different concentrations. The correlation coefficient of the fitted calibration curve was as high as 99.94% in the linear range, and the LOD of Pb was confirmed as 2.93ppm. Concentration prediction experiments were performed on a further six samples. The excellent quantitative ability of the system was demonstrated by comparison of the real and predicted concentrations of the samples. The lowest relative error was 0.043% and the highest was no more than 7.1%.展开更多
The research on the properties of graphene oxide(GO) in various media has become one of the hottest topics since GO is now the main raw material for graphene-based advanced materials. In this work, the g-ray radiati...The research on the properties of graphene oxide(GO) in various media has become one of the hottest topics since GO is now the main raw material for graphene-based advanced materials. In this work, the g-ray radiation chemistry effect of GO nanosheets and their self-aggregation behavior in t-butanol/water medium were investigated. The results show that GO nanosheets are reduced and hydroxyalkylated simultaneously by the alcohol free radicals produced by the radiolysis of t-butanol/water solution under g-ray radiation. The radiation-modified GO nanosheets will self-assemble into a self-standing graphene hydrogel when the p H of the solution is lower than 2. A hydroxyl-functionalized free-standing graphene aerogel is further obtained simply by freeze-drying. This work provides not only a general self-assembly mechanism of GO nanosheets in strong acidic alcohol/water media under high energy radiation, but also a facile and economical preparation method for hydroxyalkylated graphene-based aerogel.展开更多
The aim of this paper is to discuss the relationship between the dynamics and thermodynamics of water in the supercooled region. Reviewed case studies comprehend bulk water simulated with the SPC/E, TIP4P and TIP4P/20...The aim of this paper is to discuss the relationship between the dynamics and thermodynamics of water in the supercooled region. Reviewed case studies comprehend bulk water simulated with the SPC/E, TIP4P and TIP4P/2005 potentials, water at protein interfaces, and water in solution with electrolytes. Upon supercooling, the fragile to strong crossover in the s-relaxation of water is found to occur when the Widom line emanating from the liquid-liquid critical point is crossed. This appears to be a general characteristic of supercooled water, not depending on the applied interaction potential and/or different local environments.展开更多
Octanoic acid(OA) was selected to represent fatty acids in effluent organic matter(EOM). The effects of feed solution(FS) properties, membrane orientation and initial permeate flux on OA fouling in forward osmo...Octanoic acid(OA) was selected to represent fatty acids in effluent organic matter(EOM). The effects of feed solution(FS) properties, membrane orientation and initial permeate flux on OA fouling in forward osmosis(FO) were investigated. The undissociated OA formed a cake layer quickly and caused the water flux to decline significantly in the initial 0.5 hr at unadjusted p H 3.56; while the fully dissociated OA behaved as an anionic surfactant and promoted the water permeation at an elevated p H of 9.00. Moreover, except at the initial stage, the sudden decline of water flux(meaning the occurrence of severe membrane fouling) occurred in two conditions: 1.0.5 mmol/L Ca2+, active layer facing draw solution(AL-DS) and 1.5 mol/L Na Cl(DS); 2. No Ca2+,active layer-facing FS(AL-FS) and 4 mol/L Na Cl(DS). This demonstrated that cake layer compaction or pore blocking occurred only when enough foulants were absorbed into the membrane surface, and the water permeation was high enough to compact the deposit inside the porous substrate. Furthermore, bovine serum albumin(BSA) was selected as a co-foulant.The water flux of both co-foulants was between the fluxes obtained separately for the two foulants at p H 3.56, and larger than the two values at p H 9.00. This manifested that, at p H 3.56,BSA alleviated the effect of the cake layer caused by OA, and OA enhanced BSA fouling simultaneously; while at p H 9.00, the mutual effects of OA and BSA eased the membrane fouling.展开更多
An initial exploration was conducted using mathematical and statistical methods to obtain relevant information about the determination of the physicochemical parameters capable of controlling As uptake by ryegrass gro...An initial exploration was conducted using mathematical and statistical methods to obtain relevant information about the determination of the physicochemical parameters capable of controlling As uptake by ryegrass grown on contaminated topsoils.Concentrations of As in the soils were from 10 to 47 mg/kg,mainly in the As(V) form(57%–73%).Concentrations of As in water extracts were very low(61–700 μg/kg).It was suggested that As(Ⅲ) was mainly in the uncharged species and As(V) in the charged species.Chemometric methods revealed that the values of the ratio As(Ⅲ)/As(V) depended on the assimilated-phosphorus,the pseudo-total and water-extractable Fe contents and the soil p H.Arsenic concentrations measured in ryegrass shoots ranged from 119 to 1602 μg/kg.Positive linear correlations were obtained between As in ryegrass shoots and water extractable-As.The transfer coefficient of As correlated well with the ratio assimilated-phosphorus/Fe-oxides.As(Ⅲ)uptake by the shoot of ryegrass was controlled by the organic matter and Fe-oxide contents.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.51472071,512720616,51072043)the National Basic Research Program of China(No.2011CBA00700)
文摘The tungsten trioxide(WO3) thin films were firstly prepared by spin-coating-pyrolysis methods using the ammonium metatungstate((NH4)6H2W12O40)DMF/water solution, and successfully applied as the efficient compact layers for the planar perovskite solar cells. The influence of the WO3 film thickness and the rinsing treatment of CH_3NH_3 PbI_3 thin film with isopropanol on the photovoltaic performance of the corresponding perovskite solar cells was systematically investigated. The results revealed that the perovskite solar cell with a 62 nm thick WO3 compact layer achieved a photoelectric conversion efficiency of 5.72%, with a short circuit photocurrent density of 17.39 mA/cm^2, an open circuit voltage of 0.58 V and a fill factor of 0.57. The photoelectric conversion efficiency was improved from 5.72% to 7.04% by the isopropanol rinsing treatment.
基金Project supported by the Knowledge Innovation Project of Chinese Academy of Sciences on Water Science Research(Grant No.KJZD-EW-M03)the National Natural Science Foundation of China(Grant Nos.11474325 and 11290161)
文摘For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings difficulty to application and misleads the interpretation of relevant experiments. Here, we report a quantification scheme for the freezable bound water based on the water-content dependence of glass transition temperature, by which also the concentration range for the solutions that may undergo recrystallization finds a clear definition. Furthermore, we find that depending on the amount of the freezable bound water, different temperature protocols should be devised to achieve a complete recrystallization. Our results may be helpful for understanding the dynamics of supercooled aqueous solutions and for improving their manipulation in various industries.
基金partly supported by projects from JSPS KAKENHI (Grant No. 18340167)MEXT KAKENHI (Grant No. 20103002)+2 种基金NSFC (Grand No.90914002)China Geological Survey (Grant No. 1212011220926)the Ministry of Education of China (Grant No. 20130022110003)
文摘Silicate perovskites((Mg, Fe)SiO 3 and CaS iO 3) are believed to be the major constituent minerals in the lower mantle. The phase relation, solid solution, spin state of iron and water solubility related to the lower mantle perovskite are of great effect on the geodynamics of the Earth's interior and on ore mineralization. Previous studies indicate that a large amount of iron coupled with aluminum can incorporate into magnesium perovskite, but this is discordant with the disproportionation of(Mg,Fe)SiO 3 perovskite into iron-free MgS i O3 perovskite and hexagonal phase(Mg0.6Fe0.4)SiO 3 in the Earth's lower mantle. MnS iO 3 is the first chemical component confirmed to form wide range solid solution with Ca SiO 3 perovskite and complete solid solution with MgS i O3 perovskite at the P-T conditions in the lower mantle, and addition of Mn Si O3 will strongly affects the mutual solubility between Mg Si O3 and CaS iO 3. The spin state of iron is deeply depends on the site occupation of the Fe3+or Fe2+, the synthesis and the annealing conditions of the sample. It seems that the spin state of Fe2+ in the lower mantle perovskite can be settled as high spin, however, the existence of intermediate spin or low spin state of Fe2+ in perovskite has not been clarified. Moreover, different results have also been reported for the spin state of Fe3+ in perovskite. The water solubility of the lower mantle perovskite is related with its composition. In pure Mg SiO 3 perovskite, only less than 500 ppm water was reported. Al–Mg Si O3 perovskite or Al–Fe–MgS iO 3 perovskite in the lower mantle accommodates water of 1100 to 1800 ppm. Further experiments are necessary to clarify the detailed conditions for perovskite solid solution, to reliably analyze the valence and spin states of iron in the coexisting iron-bearing phases, and to compare the water solubility of different phases at different layers for deeply understanding the geodynamics of the Earth's interior and ore mineralization.
基金Projects(5087408750978212)supported by the National Natural Science Foundation of China+1 种基金Project(2006E106)supported by Natural Science Foundation of Shaanxi Province,ChinaProject(07JK302)supported by Special Natural Science Foundation of Shaanxi Province Education Office,China
文摘The waste water system generated in the process of production of cuprous chloride was studied.The existing forms of copper in the system and the influence of temperature and pH on the existing forms of copper ion were analyzed and determined through calculating the coefficients of copper complex distribution.In the waste water system,the main forms of copper are CuSO4, Cu2 +,CuCl + ,CuCl, 2-and2- 3 CuCl.Temperature has little influence on the distribution coefficient of Cu(Ⅱ),but has significant influence on distribution coefficient of Cu(Ⅰ).With the increase of temperature,the distribution coefficient ofCuCl, 2-increases significantly while the distribution coefficient of2- 3 CuCl decreases.The pH has nearly no influence on the distribution coefficients of various Cu(Ⅰ)-compounds,but has sizable influence on the distribution coefficients of Cu(Ⅱ)-compounds.With the increase of pH,the distribution coefficient of CuSO4(aq)increases while the distribution coefficients of Cu 2+ and CuCl + decrease.According to these results,the anion resin of 201×7 OH-and the cation resin of 732 Na were chosen to dispose the waste water solution of cuprous chloride.Finally,97.9%copper in the waste water is recovered.
文摘The paper presents a flow plasma reactor permitting modification of the properties of water/aqueous solutions by stochastic resonance amplification of vibrations of selected chemical species in water with electromagnetic noise generated during a plasma discharge. The main parameters characterizing the quality for super-pure water, tap water and water from the intake in Besko (Poland) before and after the process in the plasma reactor were presented for comparison. In addition, the <sup>17</sup>O NMR (the full width at half maximum) and electrospray ionization mass spectrometry (ESI MS) methods were used to determine differences in physicochemical parameters between the untreated and plasma-treated water. It has been established that the water subjected to plasma treatment shows much different gas absorption properties than the untreated water samples, as a function of temperature and pressure, in this paper we report exemplary data for CO<sub>2</sub>, oxygen and acetylene. The improved gas absorption properties of the plasma-treated water make it attractive for the use in industrial processes. It is worth pointing to a great capacity of the new reactor (4000 l/h), and low energy consumption (20 MJ/h) for the treatment of the above mentioned volume flow rate of water.
基金Project supported by the National Natural Science Foundation of China(Grand Nos.11025524 and 11161130520)the National Basic Research Program of China(Grant No.2010CB832903)the European Commission’s 7th Framework Programme(FP7-PEOPLE-2010-IRSES)(Grant No.269131)
文摘Structural properties of the pure water and halogen solutions at high temperatures and pressures are studied by using the molecular dynamics simulations and quantum molecular simulations. The related characters are calculated as functions of temperature and pressure. The results show that the hydrogen bonded networks become looser as temperature increases,with the collapse of the traditional tetrahedral structure. It is similar to the concentration-dependent collapse in the Na Cl solutions. However, adding other halogen elements has no further effects on the already weakly bonded water molecules.At the phase changing points, the process of hydration is evident for the bigger ions, so that the bigger the ion is, the smaller a cluster is formed.
基金supported by the Natural Science Foundation of Fujian Province (No. T08J0129)the Science and Technology Developing Foundation of Fuzhou University (No. 2008-XQ-001)2007-year New Century Talents Supporting Program of Fujian Province (No. XSJRC2007-17)
文摘A small amount of mineralizer MgO was added into Al2TiO5 synthesized from the sludge of aluminum factory to form Al(2-x)Mg(x+y)Ti(1-y)O(5-0.5x-y) solid solution and inhibit the decomposition of Al2TiO5 solid solution. It increased the content of Al2TiO5 solid solution and improved the thermal stability of materials. In this work,XRD and SEM methods were adopted to characterize the crystalline structure and microstructure of each kind of sample. Rietveld Quantification method was used to determine the content of crystalline phases in each sample. Results show as follows: the optimal addition concentration of MgO was 2.0%,and the corresponding content of Al2TiO5 solid solution which displayed irregular bulk shape was 100%; the addition of mineralizer MgO could enhance the flexural strength and thermal stability of Al2TiO5 solid solution materials. The optimal addition concentration of MgO determined by performance analysis was 2.0%,and its corresponding retention rate of thermal-shock flexural strength was 86.4%. Structure analysis and performance analysis resulted in good accordance.
文摘The intensive and inappropriate use of water, fertilizers and phytosanitary products is sources of water and soil pollution. It is thus necessary to improve the management of irrigation water in order to optimize its use and productivity, especially in regions where water resources are becoming increasingly scarce. The water flow and non-reactive solutes’ transport simulation under drip irrigation were carried out in a 3-layered soil profile distributed from top to bottom<em> i.e</em>., sandy, sandy-silty, silty-sandy-clay. The aim of this study was thus, to provide a good practice of water management associated with solutes’ application, in order to retain as much solute as possible in the root zone, which will increase the residence time of the solutes. Three treatments of water flux corresponding to 100% <em>ET</em><sub><em>c</em></sub>, 75% <em>ET</em><sub><em>c</em></sub>, 50% <em>ET</em><sub><em>c</em></sub>, combined with 100 mmol /L/ m<sup>2</sup> of NPK and 246 mmol/L/m<sup>2</sup> of urea applicable in two doses, were carried out over a period of 110 days corresponding to the duration of the cropping cycle for the intermediate variety of maize. The 100%<em> ET</em><sub><em>c</em></sub> and 75% <em>ET</em><sub><em>c</em></sub> treatments cause more loss of water and solutes, because of the sandy texture of the soil. However, a 50% <em>ET</em><sub><em>c</em></sub> water flux would reduce more water loss through drainage, and solutes’ loss due to leaching beyond the root zone, which would increase the residence time of solutes in the soil profile. Application tests of the NPK solute on different days before the 15<sup>th</sup> day after sowing were also carried out according to the technical itinerary for maize production in Burkina Faso, in order to find a favorable day for application of the solute. For the different dates of solute’s application, there was more loss of the solute as we approach the 15<sup>th</sup> day after sowing. To limit this loss and increase the residence time of the NPK solute, one could apply the solute without first supplying water, the day before and the day after the date of solute’ injection. Or, one could amend the soil with organic matter to improve its retention capacity of water, and the solutes’ residence time in the soil.
基金supported by National Natural Science Foundation of China(No.11104153)
文摘A newly developed approach for trace metal elements detection for aqueous samples analysis is presented in this paper. The idea of this approach is to improve ablation efficiency by transforming the liquid sample into a dense cloud of droplets using an ultrasonic nebulizer. The resulting droplets are then subjected to analysis by laser induced breakdown spectroscopy (LIBS). A purpose-built ultrasonic nebulizer assisted LIBS (UN-LIBS) system has been applied to the analysis of aqueous samples at trace levels of concentration. Experimental investigations of solution samples were carried out with various dissolved trace metal elements (Mn, Zn, Cu, Pb, Fe, Mg and Na) using this approach. The characteristics of UN-LIBS signal of the elements were investigated regarding the lifetime and S/B ratio and the calibration curves for trace metal elements analyses. The obtained LODs are comparable or much better than the LODS of the reported signal enhancement approaches when the laser pulse energy was as low as 30 mJ. The good linearity of calibration curves and the low LODs shows the potential ability of this method for metal elements analysis application. The density of the electrons was calculated by measuring the Stark width of the line of Ha. The possible mechanism of the LIBS signal enhancement of this approach was briefly discussed.
基金supported by an NSF grant to Cornell University,the China Scholarship Council and a Korean government MLTMA grant Development of Korea Operational Oceanographic System (KOOS) to KORDI
文摘Long waves generated by a moving atmospheric pressure distribution, associated with a storm, in coastal region are investigated numerically. For simplicity the moving atmospheric pressure is assumed to be moving only in the alongshore direction and the beach slope is assumed to be a constant in the on-offshore direction. By solving the linear shallow water equations we obtain numerical solutions for a wide range of physical parameters, including storm size (2a), storm speed (U), and beach slope (a). Based on the numerical results, it is determined that edge wave packets are generated if the storm speed is equal to or greater than the critical velocity, Ucr, which is defined as the phase speed of the fundamental edge wave mode whose wavelength is scaled by the width of the storm size. The length and the location of the positively moving edge wave packet is roughly Ut/2 〈 y 〈 Ut, where y is in the alongshore direction and t is the time. Once the edge wave packet is generated, the wavelength is the same as that of the fundamental edge wave mode corresponding to the storm speed and is independent of the storm size, which can, however, affect the wave amplitude. When the storm speed is less than the critical velocity, the primary surface signature is a depression directly correlated to the atmospheric pressure distribution.
文摘In this paper, the effects of polymer additives and nozzle shape on the proper- ties of high pressure water jet discharging into the air are investigated by theory and experiments. Criteria of judging the jet quality are put forward. And, a method that can be used in analysing the fluid flow within the nozzle is developed. Then, the calculated results are compared with the experiments that we carried out; it is shown that the degree of agreement between the two is good. At last, the mechanism to improve on the jet quality with polymer additives is discussed.
基金Financial support from the National Natural Science Foundation of China (Grant No. 11104153) is highly acknowledged.
文摘In this study, an ultrasonic nebulizer unit was established to improve the quantitative analysis ability of laser-induced breakdown spectroscopy (LIBS) for liquid samples detection, using solutions of the heavy metal element Pb as an example. An analytical procedure was designed to guarantee the stability and repeatability of the LIBS signal. A series of experiments were carried out strictly according to the procedure. The experimental parameters were optimized based on studies of the pulse energy influence and temporal evolution of the emission features. The plasma temperature and electron density were calculated to confirm the LTE state of the plasma. Normalizing the intensities by background was demonstrated to be an appropriate method in this work. The linear range of this system for Pb analysis was confirmed over a concentration range of 0-4,150ppm by measuring 12 samples with different concentrations. The correlation coefficient of the fitted calibration curve was as high as 99.94% in the linear range, and the LOD of Pb was confirmed as 2.93ppm. Concentration prediction experiments were performed on a further six samples. The excellent quantitative ability of the system was demonstrated by comparison of the real and predicted concentrations of the samples. The lowest relative error was 0.043% and the highest was no more than 7.1%.
基金supported by the National Natural Science Foundation of China (Nos. 51573175, 51473152, 51773189)Foshan Scientific and Technological Innovation Team Project (No. 2013IT100041)+1 种基金Foshan University-City Cooperation Project (Scientific and Technological Innovation Project, No. 2014HK100291)the Fundamental Research Funds for the Central Universities (Nos. WK2060200012, WK3450000001)
文摘The research on the properties of graphene oxide(GO) in various media has become one of the hottest topics since GO is now the main raw material for graphene-based advanced materials. In this work, the g-ray radiation chemistry effect of GO nanosheets and their self-aggregation behavior in t-butanol/water medium were investigated. The results show that GO nanosheets are reduced and hydroxyalkylated simultaneously by the alcohol free radicals produced by the radiolysis of t-butanol/water solution under g-ray radiation. The radiation-modified GO nanosheets will self-assemble into a self-standing graphene hydrogel when the p H of the solution is lower than 2. A hydroxyl-functionalized free-standing graphene aerogel is further obtained simply by freeze-drying. This work provides not only a general self-assembly mechanism of GO nanosheets in strong acidic alcohol/water media under high energy radiation, but also a facile and economical preparation method for hydroxyalkylated graphene-based aerogel.
文摘The aim of this paper is to discuss the relationship between the dynamics and thermodynamics of water in the supercooled region. Reviewed case studies comprehend bulk water simulated with the SPC/E, TIP4P and TIP4P/2005 potentials, water at protein interfaces, and water in solution with electrolytes. Upon supercooling, the fragile to strong crossover in the s-relaxation of water is found to occur when the Widom line emanating from the liquid-liquid critical point is crossed. This appears to be a general characteristic of supercooled water, not depending on the applied interaction potential and/or different local environments.
文摘Octanoic acid(OA) was selected to represent fatty acids in effluent organic matter(EOM). The effects of feed solution(FS) properties, membrane orientation and initial permeate flux on OA fouling in forward osmosis(FO) were investigated. The undissociated OA formed a cake layer quickly and caused the water flux to decline significantly in the initial 0.5 hr at unadjusted p H 3.56; while the fully dissociated OA behaved as an anionic surfactant and promoted the water permeation at an elevated p H of 9.00. Moreover, except at the initial stage, the sudden decline of water flux(meaning the occurrence of severe membrane fouling) occurred in two conditions: 1.0.5 mmol/L Ca2+, active layer facing draw solution(AL-DS) and 1.5 mol/L Na Cl(DS); 2. No Ca2+,active layer-facing FS(AL-FS) and 4 mol/L Na Cl(DS). This demonstrated that cake layer compaction or pore blocking occurred only when enough foulants were absorbed into the membrane surface, and the water permeation was high enough to compact the deposit inside the porous substrate. Furthermore, bovine serum albumin(BSA) was selected as a co-foulant.The water flux of both co-foulants was between the fluxes obtained separately for the two foulants at p H 3.56, and larger than the two values at p H 9.00. This manifested that, at p H 3.56,BSA alleviated the effect of the cake layer caused by OA, and OA enhanced BSA fouling simultaneously; while at p H 9.00, the mutual effects of OA and BSA eased the membrane fouling.
文摘An initial exploration was conducted using mathematical and statistical methods to obtain relevant information about the determination of the physicochemical parameters capable of controlling As uptake by ryegrass grown on contaminated topsoils.Concentrations of As in the soils were from 10 to 47 mg/kg,mainly in the As(V) form(57%–73%).Concentrations of As in water extracts were very low(61–700 μg/kg).It was suggested that As(Ⅲ) was mainly in the uncharged species and As(V) in the charged species.Chemometric methods revealed that the values of the ratio As(Ⅲ)/As(V) depended on the assimilated-phosphorus,the pseudo-total and water-extractable Fe contents and the soil p H.Arsenic concentrations measured in ryegrass shoots ranged from 119 to 1602 μg/kg.Positive linear correlations were obtained between As in ryegrass shoots and water extractable-As.The transfer coefficient of As correlated well with the ratio assimilated-phosphorus/Fe-oxides.As(Ⅲ)uptake by the shoot of ryegrass was controlled by the organic matter and Fe-oxide contents.