pH值的测定是水化学中最重要、最经常的检验项目之一.在环境统计,环境评价及环境研究等工作中常需计算其均值,然而,由于pH值的定义和标准使pH值不能采用通常计算平均值(?)=(1/n)sum from i=1 to nX_i的方法进行计算,国家环境保护局1986...pH值的测定是水化学中最重要、最经常的检验项目之一.在环境统计,环境评价及环境研究等工作中常需计算其均值,然而,由于pH值的定义和标准使pH值不能采用通常计算平均值(?)=(1/n)sum from i=1 to nX_i的方法进行计算,国家环境保护局1986年颁布的《环境监测技术规范(大气和废气部分)》中规定了:降水酸度平均值计算采用氢离子的雨量加权法计算,即:展开更多
Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure solvents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethy...Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure solvents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide at the temperature range from 293.15K to 353.15K. All these data were regressed by 2h, NRTL, Wilson, and the modified Wilson models. For the study of six, 2h, NRTL, and the modified Wilson models were found to provide an accurate mathematical representation of the experimental results, with overall average absolute relative deviations between measured and calculated values as 1.74%, 2.06%, and 3.06%, respectively. The results showed that the λh model is the most suitable for description of the solid-liquid equilibrium containing adipic acid.展开更多
Solubility of dimethyl-2,6-naphthalene dicarboxylate in acetic acid, N,N-dimethylfonnamide, N,N-dimethyl acetamide, dimethyl sulphoxide, and N-methyl-2-ketopyrrolidine were determined using a dynamic method. The measu...Solubility of dimethyl-2,6-naphthalene dicarboxylate in acetic acid, N,N-dimethylfonnamide, N,N-dimethyl acetamide, dimethyl sulphoxide, and N-methyl-2-ketopyrrolidine were determined using a dynamic method. The measured systems were correlated by UNIFAC group contribution method. A new main group （aromatic ester, ACCOO） was defined to express the activity coefficients of the aromatic ester. New interaction parameters of the ACCOO group were expressed as the first-order function of temperature and were determined from the experimental data. The calculated results for the new interaction parameters were satisfactory. The measured systems were also correlated with the Wilson and 2-h models, and the results were compared with those of the UNIFAC model.展开更多
The solubilities of trimethylolethane in butanol,methyl acetate,ethyl acetate as well as in mixed solvents of(methanol+ethyl acetate) and(ethanol+ethyl acetate) were measured with the gravimetric method in the tempera...The solubilities of trimethylolethane in butanol,methyl acetate,ethyl acetate as well as in mixed solvents of(methanol+ethyl acetate) and(ethanol+ethyl acetate) were measured with the gravimetric method in the temperature range from 283.15 K to 318.15 K under atmosphere pressure.The experiment results showed that the solubility of trimethylolethane increased with the temperature,or along with the concentration of methanol or ethanol in the solvents of(methanol+ethyl acetate) and(ethanol + ethyl acetate).In addition,the experiment values were correlated by the van't Hoff equation,Modi fied Apelblat Equation,λh Equation,CNIBS/R-K equation and Jouyban–Acree Model.The Modi fied Apelblat Equation provided the best fitting results of the solubility data of TME in the pure solvents while the CNIBS/R-K model showed the best estimation of the solubility in the binary solvent mixtures.Furthermore,the density functional theory(DFT) calculations showed that solubility in different solvents related to the strength of the interaction between the trimethylolethane and the solvent molecules.Finally,the standard molar enthalpy and molar entropy of trimethylolethane during the dissolving process was also calculated by Modi fied Apelblat equation in this work.展开更多
The aim of the study was to investigate effect of transport times of up to 12 h on pigs＇ welfare. An observation box was located on the 3rd floor of the vehicle. Device to measure temperature, humidity and video came...The aim of the study was to investigate effect of transport times of up to 12 h on pigs＇ welfare. An observation box was located on the 3rd floor of the vehicle. Device to measure temperature, humidity and video camera to monitor pigs＇ behaviors were fitted in the box. Eighteen measurements were performed during two seasons for 4, 8, and 12 h of transport time with three replications. Meat samples were taken from longissimus dorsi （LD） and the carcases were chilled for 24 h at ＋4 ~C for pH determination. To determine cortisol, glucose, lactate, and creatine kinase concentration levels, blood samples were collected before and after transport from 90 pigs and from 20 controls that were not transported for control purposes. To evaluate behavioural alterations, frequency of events and durations were considered. Highest pH24 of 5.99 ＋ 0.29 occurred during summer at 12 h transport time. Cortisol concentrations elevated during short and decreased with an increase of transport time （P 〈 0.001）. Highest and lowest glucose concentrations for winter and summer were at 8 and 12 h transport time, respectively （P 〈 0.01）. Concentrations of lactate and creatine kinase positively correlated with transport time （P 〈 0.002）. Lying, sitting, rooting and vocalization behaviours correlated with transport time （P 〈 0.009）. Certain THI values during summer surpassed normal （〉 74） level during loading. The pH24 value correlated with transport time during summer. Lactate and creatine kinase concentrations increased with an increase in transport time but for Glucose, highest value was at 8 h transport time.展开更多
A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which h...A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which have values of 28.7±0.9 ℃ ; 8.3±0.3; 831±172.5 μS/cm; 165.4±18.3 mg/L; 0.06±0.1 mg/L; 0.4±0.6 mg/L; 7.8±2.4 mg/L and 5.2±1.6mg/L, respectively. Temperature and pH were measured in the field using mercury-in-glass thermometer calibrated in degrees Celsius and pH meter, respectively. TSS and TDS were measured by grayimetric methods, while alkalinity was measured titrimetrically and DO and BOD were measured by Winkler＇s method. For the nutrients, nitrate was measured color±metrically, phosphate by Stannous Chloride method and sulphate by turbidimetric method. Mean concentration of nitrate, phosphate, and sulphate were 15.6±8.6 rag/L; 42.5±19.4 mg/L and 72.3±14.7 mg/L respectively. Nowadays, eutrophication of natural waters is one of the most significant causes of deterioration of water quality, and nitrates and phosphates are probably the key nutrients in controlling the growth of aquatic plants. Though the mean concentration of nitrates and phosphates in the reservoir water were within the acceptable limit, yet their concentrations in some locations of reservoir were high enough to encourage the growth of aquatic macrophytes which would increase productivities. Hence, it is necessary to check their further increase, and periodic monitoring and preventive measures must be adopted to save the reservoir from eutrophication.展开更多
文摘pH值的测定是水化学中最重要、最经常的检验项目之一.在环境统计,环境评价及环境研究等工作中常需计算其均值,然而,由于pH值的定义和标准使pH值不能采用通常计算平均值(?)=(1/n)sum from i=1 to nX_i的方法进行计算,国家环境保护局1986年颁布的《环境监测技术规范(大气和废气部分)》中规定了:降水酸度平均值计算采用氢离子的雨量加权法计算,即:
文摘Using a laser detecting system, solubility data were measured for adipic acid dissolved in six pure solvents, namely, cyclohexanone, cyclohexanol, acetic acid, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide at the temperature range from 293.15K to 353.15K. All these data were regressed by 2h, NRTL, Wilson, and the modified Wilson models. For the study of six, 2h, NRTL, and the modified Wilson models were found to provide an accurate mathematical representation of the experimental results, with overall average absolute relative deviations between measured and calculated values as 1.74%, 2.06%, and 3.06%, respectively. The results showed that the λh model is the most suitable for description of the solid-liquid equilibrium containing adipic acid.
文摘Solubility of dimethyl-2,6-naphthalene dicarboxylate in acetic acid, N,N-dimethylfonnamide, N,N-dimethyl acetamide, dimethyl sulphoxide, and N-methyl-2-ketopyrrolidine were determined using a dynamic method. The measured systems were correlated by UNIFAC group contribution method. A new main group （aromatic ester, ACCOO） was defined to express the activity coefficients of the aromatic ester. New interaction parameters of the ACCOO group were expressed as the first-order function of temperature and were determined from the experimental data. The calculated results for the new interaction parameters were satisfactory. The measured systems were also correlated with the Wilson and 2-h models, and the results were compared with those of the UNIFAC model.
基金Supported by the NSFC(21576206)the Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R46)
文摘The solubilities of trimethylolethane in butanol,methyl acetate,ethyl acetate as well as in mixed solvents of(methanol+ethyl acetate) and(ethanol+ethyl acetate) were measured with the gravimetric method in the temperature range from 283.15 K to 318.15 K under atmosphere pressure.The experiment results showed that the solubility of trimethylolethane increased with the temperature,or along with the concentration of methanol or ethanol in the solvents of(methanol+ethyl acetate) and(ethanol + ethyl acetate).In addition,the experiment values were correlated by the van't Hoff equation,Modi fied Apelblat Equation,λh Equation,CNIBS/R-K equation and Jouyban–Acree Model.The Modi fied Apelblat Equation provided the best fitting results of the solubility data of TME in the pure solvents while the CNIBS/R-K model showed the best estimation of the solubility in the binary solvent mixtures.Furthermore,the density functional theory(DFT) calculations showed that solubility in different solvents related to the strength of the interaction between the trimethylolethane and the solvent molecules.Finally,the standard molar enthalpy and molar entropy of trimethylolethane during the dissolving process was also calculated by Modi fied Apelblat equation in this work.
文摘The aim of the study was to investigate effect of transport times of up to 12 h on pigs＇ welfare. An observation box was located on the 3rd floor of the vehicle. Device to measure temperature, humidity and video camera to monitor pigs＇ behaviors were fitted in the box. Eighteen measurements were performed during two seasons for 4, 8, and 12 h of transport time with three replications. Meat samples were taken from longissimus dorsi （LD） and the carcases were chilled for 24 h at ＋4 ~C for pH determination. To determine cortisol, glucose, lactate, and creatine kinase concentration levels, blood samples were collected before and after transport from 90 pigs and from 20 controls that were not transported for control purposes. To evaluate behavioural alterations, frequency of events and durations were considered. Highest pH24 of 5.99 ＋ 0.29 occurred during summer at 12 h transport time. Cortisol concentrations elevated during short and decreased with an increase of transport time （P 〈 0.001）. Highest and lowest glucose concentrations for winter and summer were at 8 and 12 h transport time, respectively （P 〈 0.01）. Concentrations of lactate and creatine kinase positively correlated with transport time （P 〈 0.002）. Lying, sitting, rooting and vocalization behaviours correlated with transport time （P 〈 0.009）. Certain THI values during summer surpassed normal （〉 74） level during loading. The pH24 value correlated with transport time during summer. Lactate and creatine kinase concentrations increased with an increase in transport time but for Glucose, highest value was at 8 h transport time.
文摘A study about some physicochemical parameters of Egbe reservoir was carried out from September 2005 to December 2006. The parameters include mean temperature, pH, conductivity, alkalinity, TSS, TDS, DO and BOD which have values of 28.7±0.9 ℃ ; 8.3±0.3; 831±172.5 μS/cm; 165.4±18.3 mg/L; 0.06±0.1 mg/L; 0.4±0.6 mg/L; 7.8±2.4 mg/L and 5.2±1.6mg/L, respectively. Temperature and pH were measured in the field using mercury-in-glass thermometer calibrated in degrees Celsius and pH meter, respectively. TSS and TDS were measured by grayimetric methods, while alkalinity was measured titrimetrically and DO and BOD were measured by Winkler＇s method. For the nutrients, nitrate was measured color±metrically, phosphate by Stannous Chloride method and sulphate by turbidimetric method. Mean concentration of nitrate, phosphate, and sulphate were 15.6±8.6 rag/L; 42.5±19.4 mg/L and 72.3±14.7 mg/L respectively. Nowadays, eutrophication of natural waters is one of the most significant causes of deterioration of water quality, and nitrates and phosphates are probably the key nutrients in controlling the growth of aquatic plants. Though the mean concentration of nitrates and phosphates in the reservoir water were within the acceptable limit, yet their concentrations in some locations of reservoir were high enough to encourage the growth of aquatic macrophytes which would increase productivities. Hence, it is necessary to check their further increase, and periodic monitoring and preventive measures must be adopted to save the reservoir from eutrophication.
