不同醋量醋煮对商陆毒性及药效的影响

目的 :考察不同醋量对商陆毒性及药效的影响。方法 :采用急性毒性实验 (测LD50 ) ,祛痰实验 (酚红排泌法 )及利尿实验 (滤纸法 )。结果 :商陆醋制后毒性明显降低 ,利尿作用有所缓和 ;生品和 30 %醋煮品祛痰效果较好 ,而 5 0 % ,10 0 %醋量醋煮制商陆较生品差。结论 :商陆以 30 %醋煮制为佳。

基于pH传感器测定食醋总酸量的实验研究

利用 pH 传感器测定食醋与氢氧化钠中和滴定过程中溶液 pH 的实时变化，通过求导进而确定反应终点，无需考虑食醋本身颜色对反应终点判定的影响，是一个紧密联系科学、技术、社会与环境的典型的定量实验案例。引进该实验技术，有利于学生对定量方法的学习和科学思维的培养，促进学生认识到科学仪器的进步可以将近代经典实验转变为现代实验的事实。

活性炭脱色对食醋总酸量的影响

研究活性炭脱色对食醋总酸量的影响。以保宁醋稀释10倍为供试品工作液，利用酸碱滴定法采用酸碱指示剂和酸度计同时监测溶液pH的变化确定终点，通过消耗NaOH体积反映对总酸量的影响，监测在450nm处吸光度的变化反应脱色效果，研究了加入不同活性炭用量和脱色时间对食醋总酸量和脱色效果的影响，同时研究了活性炭脱色对食醋中可能有的几种无色有机酸的酸量的影响。结果表明：只要用活性炭脱色，测定食醋的总酸量总是偏低，活性炭脱色对几种无色有机酸的酸量有不同程度的影响。不能用活性炭脱色后，用指示剂确定终点酸碱滴定法测定食醋的总酸量。

高中化学实验与数字化实验研究 ——《食醋中总酸量的测定》的应用

数字化实验是实验过程中利用传感器和数据采集 器等仪器采集实验数据然后传送到处理器,对数据进行快速处 理、分析并显示的实验方式,能把数字化实验不易观察的化学 现象以图像的形式展示出来,从而更好地阐述原理,突破教学 难点。本文以《食醋中总酸量的测定》这节课为例,展示数字化 实验的应用。

立足课本 发掘学科内探究活动小课题——记探究活动案例一则

学科内探究活动小课题是实施科学探究的一种好途径 ,课本中蕴含着丰富的题材可供我们发掘。本文以相关案例《食醋中总酸量的测定》为例 。

Vapor-Liquid Equilibrium Measurements and Modeling for Ternary System Water ＋ Ethanol ＋ 1-Butyl-3-methylimidazolium Acetate

Vapor-liquid equilibrium(VLE) data were measured for ternary system water + ethanol + 1-butyl-3methylimidazolium acetate([bmim][OAc]),in a relatively wide range of ionic liquid(IL) mass fractions up to 0.8.Six sets of complete T-x-y data were obtained,in which the mole fraction of ethanol on IL-free basis was fixed separately at 0.1,0.2,0.4,0.6,0.8,and approximate 0.98.The non-random-two-liquid(NRTL) and electrolyte non-random-two-liquid(eNRTL) equations were used for correlation,showing similar deviations.The ternary VLE was also modeled with the correlation from two data sets,with the mole fractions of ethanol on IL-free basis being 0.1 and approximate 0.98.The VLE data were also reproduced satisfactorily.With the eNRTL model,the root-mean-square deviation for temperature is 0.79 K and that for vapor-phase mole fraction is 0.0094.The calculations are in good agreement with experimental data.The effect of the IL on the VLE behavior of the volatile components is also illustrated.

Experimental Measurements and Correlations Isobaric Vapor-Liquid Equilibria for Water ＋ Acetic Acid ＋ Sec-butyl Acetate at 101.3 kPa

Isobaric vapor-liquid equilibrium(VLE) data for acetic acid + sec-butyl acetate and water+acetic acid + sec-butyl acetate systems were determined at 101.3 kPa using a modified Rose type.The nonideality of the vapor phase caused by the association of the acetic acid was corrected by the chemical theory and Hayden-O'Connell method.Thermodynamic consistency was tested for the binary VLE data.The experimental data were correlated successfully with the Non-Random Two Liquids(NRTL) model.The Root Mean Square Deviation(RMSD) of the ternary system was 0.0038.The saturation vapor pressure of sec-butyl acetate at 329 to 385 K was measured by means of two connected equilibrium cells.The vapor pressures of water and sec-butyl acetate were correlated with the Antoine equation.The binary interaction parameters and the ternary VLE data were obtained from this work.

Process optimization of an industrial acetic acid dehydration progress via heterogeneous azeotropic distillation

The simulated process model of the HAc dehydration process under actual overloaded condition was conducted by amending the model of standard condition in our previous work using the process data collected from actual production. Based on the actual process model, the operation optimization analysis of each plant(HAc dehydration column, decanter and NPA recycle column) was conducted using Residue Curve Maps(RCMs),sensitivity analysis and software optimization module. Based on the optimized parameters, the influence of feed impurity MA and the temperature of decanter on the separating effect and energy consumption of the whole process were analyzed. Then the whole process operation optimizing strategy was proposed with the objective that the total reboiler duty Q Total of C-1 and C-3 reaches the minimum value, keeping C-1 and C-3 at their optimized separation parameters obtained above, connecting all the broken recycle and connection streams, and using the temperature of D-1 as operation variable. The optimization result shows that the total reboiler duty Q Total of the whole process can reach the minimum value of 128.32 × 10~6 k J·h^(-1) when the temperature of decanter is 352.35 K, and it can save 5.94 × 10~6 k J·h^(-1), about 2.56 t·h^(-1) low-pressure saturated vapor.

Homogeneous Acetylation of Cellulose at Relatively High Concentrations in an Ionic Liquid

At relatively high cellulose mass concentrations(8%,10%,and 12%),homogeneous acetylation of cellulose was carried out in an ionic liquid,1-allyl-3-methylimidazolium chloride(AmimCl).Without using any catalyst,cellulose acetates(CAs)with the degree of substitution(DS)in a range from 0.4 to 3.0 were synthesized in one-step.The effects of reaction time,temperature and molar ratio of acetic anhydride/anhydroglucose unit(AGU) in cellulose on DS value of CAs were investigated.The synthesized CAs were characterized by means of FT-IR, NMR,and solubility,mechanical and thermal tests.After the acetylation,the used ionic liquid AmimCl was easily recycled and reused.This study shows the potential of the homogeneous acetylation of cellulose at relatively high concentrations in ionic liquids in future industrial applications.

Measurement and Correlation of Vapor-Liquid Equilibria for Hexamethyl Disiloxane+Vinyl Acetate System at 101.3 kPa

Vapor-liquid equilibrium data of hexamethyl disiloxane+vinyl acetate system at 101.3kPa were measured by using double circulating vapor-liquid equilibrium still.The thermodynamic consistency of the VLE data was examined by Herrington method.Experimental data was correlated by non-random two-liquid(NRTL),Wilson and universal quasichemical(UNIQUAC)parameter models.All the models satisfactorily correlated with the VLE data.The result showed that the NRTL model was the most suitable one to represent experimental data satisfactorily.The system had a minimum temperature azeotrope at 345.71 K and the mole azeotropic composition was 0.0541.

Adiabatic correction for the esterification of acetic anhydride by methanol via accurate kinetics

In the field of adiabatic correction for complex reactions,a simple one-stage kinetic model was used to estimate the real reaction kinetics.However,this assumption simplified the real process,inevitably generated inaccurate or even unsafe results.Therefore,it was necessary to find a new correction method for complex reactions.In this work,esterification of acetic anhydride by methanol was chosen as an object reaction of study.The reaction was studied under different conditions by Reaction Calorimeter(RC1).Then,Thermal Safety Software(TSS)was used to establish the kinetic model and estimate the parameters,where,activation energies for three stages were67.09,81.02,73.77 kJ?mol^(-1)respectively,and corresponding frequency factors in logarithmic form were 16.05,19.59,15.72 s^(-1).In addition,two adiabatic tests were performed by Vent Sizing Package2(VSP2).For accurate correction of VSP2 tests,a new correction method based on Enhanced Fisher method was proposed.Combined with kinetics,adiabatic correction of esterification reaction was achieved.Through this research,accurate kinetic parameters for a three-step kinetic model of the esterification reaction were acquired.Furthermore,the correlation coefficients between simulated curves and corrected curves were 0.976 and 0.968,which proved the accuracy of proposed new adiabatic correction method.Based on this new method,conservative corrected results were able to be acquired and be applied in safety assessment.

Karyotype Analysis of the Fiddleneck （Phacelia tanacetifofia Benth.）

Two varieties of fiddleneck （Phacelia tanacetifolia Benth.） plant were determined for visualizing somatic chromosomes. The 4-5 days old root tips were pre-treated in 6% a-monobromonaphtalane in ＋4 ℃ for 7.5 h, then fixed in glacial acetic acid for 30 min and transferred to 70% ethanol for long storage. When the root tips were analyzed, they were hydrolyzed with 1 N HCI for 13 min at room temperature （25 ℃）. After hydrolyzing, root tips were stained with 2% aceto orcein in darkness for 2.5 h. The squash method for preparation was used for chromosomal investigations. The chromosome length （C）, relative length （RL）, the long arm （L） and short arm （S） lengths, arm ratio （AR; L/S） and centromefic index （S/C） were calculated for caryologic parameters. The ideograms and detailed chromosome morphology measurements of the species were performed by the use of MicroMeasure 3.3. According to results, fiddleneck （Phacelia tanacetifolia Benth.） has 2n = 22 chromosomes and the karyotype formulas of two varieties of fiddleneck were 16 median and 6 submedian （16 m ＋ 6 sm）.

Estrus Grouping in Sheep Treated with Melengestrol Acetate （MGA）

In Mexico the predominant sheep production system is the semi-extensive with grazing during the day and stanchion afternoon and night. Sheep herd are usually small, approximately 10 to 75 heads. The objectives of these systems are savings and marketing of lambs. Meat is the main economic product of this kind, the breeding is long, which do not control the delivery dates and ages of the sheep are not uniform, affecting the demand for the local market （for the months of June and December）. Therefore the aim of this work was implement a technology that allows the grouping of the estrus and therefore group deliveries for batches of uniform lambs. This technology was designed to suppress the estrus and heifers growth promoter of feedlots, this technology is melengestrol acetate （MGA） which is a synthetic progesterone oral administration that it is easy to manage in the food or alone, economic that it does not represent any risk for sheep females of abortive type, evaluating the effect of the MGA on rate of estrus and gestation in sheep. Work developed in the municipality of Charo from Michoac^in State, M6xico, 20 hair sheep divided in two groups of 10 female, group one treated with MGA and group tow was the whitens. 100% of the sheep treated with a dose of 0.45 mg MGA/head/day for 17 days orally, presented estrus grouped in 5-10 days; however only 50% of the sheep of the witness group presented estrus. In the experimental group there was a rate of 70% with a gestation difference time of no more than ten days gestation and witness group 50%. The MGA is an efficient alternative for the producer of sheep when administered 0.45 mg MGA/head/day for 17 days because inhibits the estrus and once withdrawn treatment manifests estrus synch with which get a rate of gestation elevated by natural riding.

Effects of a low-radiotoxicity uranium salt(uranyl acetate) on biochemical and hematological parameters of the catfish,Clarias gariepinus

Specimens of Clarias gariepinus were treated with lethal(70,75,80,85,90,and 95 mg/L) and sub-lethal concentrations(8,12 and 16 mg/L) of uranyl acetate,a low-radiotoxicity uranium salt. The LC 50 value was registered as 81.45 mg/L. The protein and glycogen concentrations in liver and muscles were decreased in the fish exposed to sub-lethal concentrations. The red blood cell(RBC) and white blood cell(WBC) counts,haemoglobin(Hb) concentration and haematocrit(Hct) values were decreased. Different blood indices like mean corpuscular volume(MCV),mean corpuscular haemoglobin(MCH) and mean corpuscular haemoglobin concentration(MCHC) were negatively affected. Level of plasma glucose was elevated whereas protein was decreased. The level of calcium concentration(Ca) was declined in the blood of exposed fish whereas magnesium(Mg) remains unchanged. The activity level of glutamic-oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) was elevated in exposed fish. These effects were more pronounced in the last period of exposure and in higher concentrations. Results of the present study indicate that uranyl acetate has adverse effects on C larias gariepinus and causes changes in the biochemical and hematological parameters of the fish.