土壤湿度对不同水溶度除草剂药效的影响

室内模拟不同土壤湿度条件 ,以稗草为生物测定材料 ,运用二次正交旋转组合设计 ,建立快杀稗、大惠利、扑草净、恶草灵 4种除草剂目标函数 (对稗草的抑制率 )与决策变量 (除草剂用量及土壤湿度二因子 )的数学模型。对备选除草剂模型的解析与比较结果表明 :土壤湿度是影响土壤处理除草剂药效的重要因素 ,4种除草剂药效随土壤湿度的提高而提高 ;除草剂的施药水平越低 ,土壤湿度对药效的发挥影响越大 ;除水溶度极低的除草剂外 ,除草剂的水溶度越大 ,土壤湿度的变化对其药效影响越大 ;土壤湿度差异对水溶度极低的除草剂药效影响 ,在低于 37.5 %条件下影响不大 ,高于 37.5 %时则大于其它除草剂 ;土壤湿度的改善是一条有效降低除草剂用量的途径。

用70型渗透仪求试样“最大分子水容度”的方法计算给水度

用７０型渗透仪求试样“最大分子水容度。的方法，计算粗粒土的给水度。

Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions

The thermodynamic properties of the most important NaOH-NaAI（OH）4-H20 system in Bayer process for alumina production were investigated. A theoretical model for calculating the equilibrium constant of gibbsite dissolved in sodium hydroxide solution was proposed. New Pitzer model parameters and mixing parameters for the system NaOH-NaAI（OH）4-H20 were yielded and tested in the temperature range of 298.15-373.15 K. The results show that the proposed model for calculating the equilibrium constant of gibbsite dissolution is applicable and accurate. The obtained Pitzer model parameters of β（0）（NaAl（OH）4）、β（1）（NaAl（OH）4）和CΦ（NaAl（OH）4）,Al（OH）4 for NaAI（OH）4, the binary mixing parameter of θ（OH-Al（OH）4-） with OH-, and the ternary mixing parameter of ψ（Na＋OH-Al（OH）4-） for AI（OH）4- with OH- and Na＋ are temperature-dependent. The prediction of the equilibrium solubility of gibbsite dissolved in sodium hydroxide solution was feasible in the temperature range of 298.15-373.15 K.

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in aqueous solutions and its applications in binary and ternary aqueous solutions

A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.

水造房屋

在秘鲁的汪涅维列卡水银矿附近,,到处可见一种用水建造的房屋。当地人在需要建造房屋时,就把地下一股热的泉水用巨大的水管引导出来,注入原先设计好的模子建房屋。原来,汪涅维列卡水银矿附近的泉水在地下即溶解了大量的石灰石、石膏和石英等物质,当这种水溶度达到饱和时,它就凝结起来,因此即可用它建造房屋。这种水造房屋造价低廉,受到居民的欢迎。

Excess Molar Volume, Viscosity and Heat Capacity for the Mixture of 1,2-Propanediol-Water at Different Temperatures

Experimental densities, viscosities and heat capacities at different temperatures were presented over the entire mole fraction range for the binary mixture of 1,2-propanediol and water. Density values were used in the determination of excess molar volumes, VE. At the same time, the excess viscosity was investigated. The values of VE and E were fitted to the Redlich-Kister equation. Good agreement was observed. The excess volumes are negative over the entire range of composition. They show an U-shaped-concentration dependence and decrease in absolute values with increase of temperature. Values of E are negative over the entire range of the composition, and has a trend very similar to that of VE . The analysis shows that at any temperature the specific heat of mixture is a linear function of the composition as x1 > 20%. All the extended lines intersect at one point. An empirical equation is obtained to calculate the specific heat to mixture at any composition and temperature in the experimental range.

Effects of temperature and phosphoric acid addition on the solubility of iron phosphate dihydrate in aqueous solutions

As important controlling factors for the synthesis of iron phosphate materials by liquid-phase precipitation, the solubilities of iron phosphate dihydrate were systematically measured at H3PO4 concentrations from 1.13 wt% to 10.7 wt% temperature from 298.15 to 363.15 K, and atmosphere pressure in this work. The solubility was found to increase 5 orders of magnitude or more with increasing the concentration of phosphoric acid, and de- crease 1 to 2 orders of magnitude with increasing the equilibrium temperature. The phosphoric acid addition and temperature were found to affect the solubility of iron phosphate dihydrate by the formation or dissociation of coordination species, which could further accelerate the phase transformation from the amorphous iron phosphate dihydrate to orthorhombic iron phosphate dehydrate by dissolution-recrystallization mechanism. The high dependences of the solubility of iron phosphate materials on HsPO4 concentration and temperature were also well predicted by calibration equations, which are meaningful for quantitatively understanding the precipitation process and sequential crystalline structure transformation and pursuing a rational strategy for syn- thesizing specific iron phosphate materials.

P Fractions in Drainage Waters from the Broadbalk Continuous Wheat Experiment at Rothamsted

Total P (TP), total participate P (PP), total dissolved P (TDP), molybdatereactive P (MRP) and dissolved organic P (DOP) were determined in waters from pipe-drains (at 65-cmdepth) from the Broadbalk Experiment at Rothamsted Research, UK. Average TPand PP exceeded 1 mgL^(-1) in about half of the 12 plots receiving superphosphate for the 5 measurements taken betweenDecember 2000 and April 2001. Ranging between 33.8% and 87.3% of TP, PP was the largest P fractionin drainage waters, with DOP, ranging from 0.5% to 26.2% of TP, being the smallest fraction Meanproportions of PP, MRP and DOP in TP in drainage waters were 63.4%, 32.5% and 4.1%, respectively.These findings support previous findings that P losses from soil to drainage waters were muchlargerthan previously thought, and could therefore make a significant contribution to eutrophication.

Measurement and Correlation of Solubility for Propylene in 2-Butanol+Water Solutions

In order to obtain solubility data of propylene in 2-butanol+water solutions, gas-liquid equilibrium(GLE) experiment was carried out at 303.15--333.15 K, 0.3-1.2 MPa with static equilibrium still. Original mass ratios of 2-butanol to water are 1:0，9:1,8:2 and 7:3, respectively. The equilibrium data are correlated with an empirical correlation. The average relative deviation (ARD) between experimental and calculated values is 2.15%,and the maximum relative deviation (MRD) is less than 5%.

Enhancement of Cd Solubility and Bioavailability Induced by Straw Incorporation in Cd-Polluted Rice Soil

Of the factors affecting migration and bioavailability of toxic metals in heavy metal contaminated soil, DOC （dissolved organic carbon） provides binding sites for metal cations and reduces the fixation and adsorption of heavy metals by soil solid phase. Elevation of DOC level due to the direct incorporation of crop residues may lead to enhanced accumulation of toxic metals in crop body grown in polluted farmland. In this study, an incubation experiment and a pot experiment were conducted respectively to investigate the effects of wheat straw incorporation on DOC level, cadmium availability, and Cd accumulation in rice plant, and to establish the relation between Cd solubility and DOC level. A Cd-contaminated rice soil was used and incorporated with different rates （0%, 0.5% and 1%） of wheat straw in both experiments. Results showed that the change pattern of Cd in soil solution was very similar to that of DOC level. Wheat straw addition significantly elevated Cd and DOC level in soil solution while NH4NO3-extrated Cd was not affected. There existed a close linear correlation between soluble Cd and DOC level. Enhanced Cd accumulation in rice plant, grown in a Cd contaminated soil, induced by wheat straw incorporation was observed in this study.

Volumetric and Viscometric Studies of 4-Aminobutyric Acid in Aqueous Solutions of Salbutamol Sulphate at 308.15, 313.15 and 318.15K

Density （ρ） and viscosity （η） measurements were carried out for 4-aminobutyric acid in 0.0041,0.0125 and 0.0207 mol·L-1 aqueous salbutamol sulphate at T=308.15,313.15 and 318.15K.The measured values of density and viscosity were used to estimate some important parameters such as apparent molar volume Vφ,limiting apparent molar volume Vφ0,transfer volume △Vφ0,hydration number Hn,second derivative of infinite dilution of partial molar volume with temperature 2Vφ0/T2,viscosity B-coefficients,variation of B with temperature dB/dT,free energy of activation per mole of solvent △μ10＊ and solute △μ20＊,activation entropy △S20＊ and activation enthalpy △H20＊ of the amino acids.These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.

Measurement and correlation of solubility of diosmin in four pure solvents and β-cyclodextrin solution at 298.15K to 333.15K

The aim of present study was to measure and correlate the solubility of poorly water-soluble flavonoid diosmin in water, ethanol, isopropyl alcohol （IPA）, polyethylene glycol-400 （PEG-400） and β-cyclodextrin （β-CD） aqueous solution （0.02 mol·L^-1 ）. The solubility of diosmio was measured using the shake flask method from （298.15 to 333.15） K at atmospheric pressure. The experimental solubilities of diosmin were regressed by the modified Apelblat model with a relative deviation in the range of 0.048% to 5.940%. The correlation coefficients were observed in the range of 0.9957 to 0.9995. The solubility of diosmin was found to be increased with temperature in all sample matrices investigated. The mole fraction solubility of diosmin was found to be higher in 5-CD aqueous solution and PEG-400 as compared to water, ethanol and IPA. Based on solubility data of present study, diosmin was considered as practically insoluble in water, insoluble in ethanol ＆ IPA and soluble in PEG- 400 and β-CD aqueous solution.

Densities, conductivities, and viscosities of aqueous solutions of N-hexyl,methylpyrrolidinium bromide and N-butyl, methylpyrrolidinium bromide at different temperatures

The densities, conductivities, and viscosities were measured for ternary solutions of N-hexyl,methylpyrrolidinium bromide([PP1,6]Br)- N-butyl,methylpyrrolidinium bromide([PP1,4]Br)-H2 O and its binary subsystems [PP1,6]Br-H2 O and [PP1,4]Br-H2 O at(298.15, 303.15, 308.15, and 313.15) K, respectively. The results were used to test the predictability of the simple equations established for the prediction of density, conductivity,and viscosity of the mixed electrolyte solutions. The results show that the examined simple equations can offer good predictions for density, conductivity, and viscosity of the mixed ionic liquid solutions in terms of the corresponding properties of its binary subsystems of equal ionic strength.

Volumetric and Transport Properties of Aqueous NaB（OH）4 Solutions

Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB（OH）4 solutions precisely measured as functions of concentration at different temperatures （293.15, 298.15, 303.15, 313.15 and 323.15 K） are presented. Polyborate distributions in aqueous NaB（OH）4 solution were calculated, covering all the concentration range, B（OH）4 is the most dominant species, other polyborate anions are less than 5.0%. The volumetric and the transport properties were discussed in detail, both of these properties indicate that B（OH）4 behaves as a struc- ture-disordered anion.

EFFECT OF WATER ACIDITY ON THE STRUCTURES AND PERFORMANCES OF VPO CATALYST FOR BUTANE OXIDATION

The water acidity has significant influences on the structures of both catalytic precursors and catalysts as well as catalytic performances. If the pH of water is higher than or equal to 3.0, the precursors contain pure (VO) 2P 2O 7·2H 2O and activated catalysts have (VO) 2P 2O 7 and β VOPO 4. When the pH of the water is lower than 3.0, the precursors are made up of (VO) 2P 2O 7·2H 2O and (VO) 2P 2O 7·4H 2O and the activated catalysts consist of (VO) 2P 2O 7 as well as α VOPO 4. Among the catalysts which had experienced water treatment, the catalyst has the best selectivity and highest mass yield to maleic anhydride when pH is 3.0. But all the catalysts show a similar activity for butane oxidation regardless of the pH. Furthermore, the more the (VO) 2P 2O 7·4H 2O in the catalyst, the lower the selectivity and mass yield to maleic anhydride. The (VO) 2P 2O 7·4H 2O in the precursor can be eliminated by controlling the water treatment with pH≥3.0 to ensure the catalyst having excellent behavior.

Correlation of ^1H NMR Chemical Shift for Aqueous Solutions by Statistical Associating Fluid Theory Association Model

1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAPT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.

Conductivity of Oxalic Acid in Aqueous Solution at Low Concentration

Oxalic acid is a weak and unsymmetrical bi-basic acid. There exist dissociation and association equilibria among the species in aqueous solution. The molar conductivity of the solution is the sum of the ionic contributions.Based on this idea, a new prediction equation of ionic conductivity was proposed at low concentration. The molar conductivities of the solution and its relevant ions were calculated respectively. The results obtained were in good agreement with those from experiments and the Quint-Viallard equation.

Relationships between Different Preparations of Cotton Hollow Yarn and Water Soluble PVA Extraction

In this paper cotton hollow yarns were obtained from the core spun yams which were produced on a little modified conventional experiment ring frame with water soluble staple PVA yam as the core. For comparison, yams with same linear densities, same twists of the sheath, different linear densities, different twist directions of the core were prepared. The results show that the tensile strengths of the hollow yarns decrease first, then increase and decrease again, at last the tensile strength trends to reach a steady state with the soluble PVA core extraction proceeding. And when the sheath linear densities of the core spun yams are constant, their twist and twist direction are same as that of the core it will be easier to remove the core of the yam with a higher core size. When the linear densities of the sheath and the core are all constant, the twists of them are same, it will be easier to remove the core of the yam with a different twist direction of core to the sheath.

Density and Viscosity of Ternary Systems(Poloxamer 188+Ethanol/ Acetone+Water)at Temperatures from 288.15 K to 308.15 K

The densities and viscosities of ternary systems(Poloxamer 188+ethanol/acetone+water)were meas- ured at 288.15,293.15,298.15,303.15,308.15 K and atmospheric pressure for different mass fractions of Poloxamer 188(0 to 0.02)in aqueous solution and different solvent volume fractions of ethanol/acetone(0 to 0.3)in Poloxamer 188 aqueous solution.The densities were measured by a pycnometer,while the viscosities were measured using two Ubbelohde capillary viscometers.The correlations of density and viscosity of these ternary systems are obtained by fitting the experimental data at different temperatures,mass fractions and volume fractions.

Coupled effect of viscosity enhancing admixtures and superplasticizers on rheological behavior of cement paste

The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC)and Welan gum,and two types of SPs,i.e.polycarboxylate(PCA)and polynaphthalenesulfonate(PNS)were used as admixtures for cement paste.Rheological curves of cement paste and simulated pore solution containing VEA and SP were tested.Simulated pore solution test results show that molecules of different SPs may generate different effects on the viscosity of VEA solutions.Hershel-Bulkley(H-B)model was used to fit rheological curve of cement paste.Strong interaction between PNS and HPMC was observed in this work.