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A further study of the kinetics and optimization of the essential oil hydrodistillation from lavender flowers

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Chinese Journal of Chemical Engineering 2021年第1期34卷 126-130页

作者： Aleksandra Perovic Mihajlo Z.stankovic Vlada B.Veljkovic Milan D.Kostic olivera s.stamenkovic University of Niš Faculty of TechnologyBulevar oslobodjenja 124Leskovac 16000Serbia The serbian Academy of sciences and Arts Knez Mihailova 35Belgrade 11000Serbia

Hydrodistillation has commonly been used to recover essential oil from various plant materials,including lavender(Lavandula officinalis) flowers.The main objectives of the present study were to model the kinetics of the lavender essential oil(LEO) hydrodistillation using a phenomenological model,to evaluate the statistical significance of the hydromodule and hydrodistillation time on LEO yield combining a 4~2 full factorial design with the response surface methodology,to model statistically LEO yield by multiple non-linear regression and to determine the optimal process conditions that provided the maximum LEO yield.The fast-essential oil distillation(washing stage) in the initial period and the slow diffusion stage until the saturation occurring simultaneously were observed,justifying the use of the phenomenological model.With increasing the hydromodule,the saturation LEO yield and the washable fraction of the LEO decreased while the washing and diffusion rate constants increased.Knowledge of the LEO oil yield and the hydrodistillation kinetics is important from the techno-economical point of view.

关键词： Essential oil Lavender Lavandula officinalis L. Kinetics Hydrodistillation Modeling

Modeling of biodiesel production: Performance comparison of Box–Behnken, face central composite and full factorial design

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Chinese Journal of Chemical Engineering 2019年第7期27卷 1690-1698页

作者： Vlada B.Veljkovic Ana V. Velickovic Jelena M. Avramovic olivera s. stamenkovic University of Nis Faculty of TechnologyBulevar oslobodenja 124Leskovac 16000Serbia Research&Development Center "Alfatec" Bulevar Nikole Tesle 63/5Nis 18000Serbia

The performances of the response surface methodology(RsM)in connection with the Box–Behnken,face central composite or full factorial design(BBD,FCCD or FFD,respectively)were compared for the use in modeling of the NaOH-catalyzed sunflower oil ethanolysis.The influence of temperature,catalyst loading,and ethanol-to-oil molar ratio(EOMR)on fatty acid ethyl esters(FAEE)content was evaluated.All three multivariate strategies were efficient in the statistical modeling and optimization of the influential process variables but BBD and FCCD realization involved less number of experiments,generating smaller costs,requiring less work and consuming shorter time than the corresponding FFD.All three designs resulted in the same optimal catalyst loading(1.25%of oil)and EOMR(12:1).The reduced two-factorinteraction(2 FI)models based on the BBD and FCCD defined a range of optimal reaction temperature(25℃–75℃)and 25℃,respectively while the same model based on the 33 FFD appointed 75℃.The predicted FAEE content of about 97%–98.0%was close to the experimentally obtained FAEE content of about 97.0%–97.6%under the optimal reaction conditions.Therefore,the simpler BBD or FCCD might successfully be applied for statistical modeling of biodiesel production processes instead of the more extensive,more laborious and more expensive FFD.

关键词： Biodiesel Box-Behnken design Model reduction Face central composite design Full factorial design Optimization

Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

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Chinese Physics B 2016年第1期25卷 697-705页

作者： M N stankov A P Jovanovie V Lj Markovic s N stamenkovic Department of Physics Faculty of Sciences and MathematicsUniversity of Ni Viegradska 33Ni 18001Serbia

The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approx- imate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by Ar＋ ions, produced by atomic-to-molecular conversion of Ar＋ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as con- version maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional （1D） model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional （2D） model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes.

关键词： argon discharge afterglow relaxation fluid model plasma reactions

Validation of the Glaucoma Quality of Life-15 Questionnaire in serbian language

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International Journal of Ophthalmology(English edition) 2018年第10期11卷 1674-1684页

作者： Ivan sencanic Tatjana Gazibara Jelena Dotlic Miroslav stamenkovic Vesna Jaksic Marija Bozic Anita Grgurevic Clinic for Eye Disease "Prof. dr Ivan stankovic" University Medical Center "Zvezdara" Institute of Epidemiology Faculty of Medicine University of Belgrade Faculty of Medicine University of Belgrade Faculty of special Education and Rehabilitation University of Belgrade Clinic for Eye Disease "Prof. dr Djordje Nesic" Clinical Center of Serbia

AIM：To translate the Glaucoma Quality of Life-15（GQL-15）to serbian language and asses its validity and reliability in the population of serbian patients.METHODs：The study included 177 glaucoma patients.Clinical parameters（visual acuity,mean defect and square root of loss variance of visual field）and socio-demographic data were collected.Patients were stratified according to the Nelson’s glaucoma staging system as mild,moderate and advanced glaucoma.All patients filled out the GQL-15 and National Eye Institute Visual Function Questionnaire（NEI-VFQ 25）.The GQL-15 was translated following the internationally-accepted methodology,and its psychometric properties were assessed by using classical test theory and Rasch analysis.REsULTs：The mean total score for the GQL-15 was 20.68±7.31.The Cronbach’s alpha coefficient for the whole scale was 0.89（central and near vision,α=0.24;peripheral vision,α=0.85;glare and dark adaptation,α=0.83）.Factor analysis established 4 factors（70.3% of variance）：two corresponding to the original factors and two new factors specific for the serbian population.The GQL-15 score correlated positively with almost all clinical parameters and NEI-VFQ 25 proving good criterion validity.Correlation of the GQL-15 total score on test-retest confirmed appropriate scale reproducibility（ρ=0.96,P〈0.001）.The GQL-15 discriminated well advanced from mild and moderate glaucoma.In Rasch analysis we obtained adequate item（0.95）reliability index.Almost all items had infit and outfit mean squares in the accepted range.CONCLUsION：serbian version of the GQL-15 demonstrates adequate reliability and validity.This version of the GQL-15is a valid instrument for evaluation of quality of life among serbian speaking patients with glaucoma and can be applied in daily clinical work.

关键词： glaucoma GQL-15 scale validation serbian

The Applicability of Fluid Model to Electrical Breakdown and Glow Discharge Modeling in Argon

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Chinese Physics Letters 2015年第2期32卷 81-85页

作者： M. N. stankov M. D. Petkovic V. Lj. Markovic s. N. stamenkovic A. P. Jovanovic Department of Physics Faculty of Sciences and Mathematics University of Nis Visegradska 33 Nis18001 Serbia Department of Computer science Faculty of Sciences and Mathematics University of Nis Visegradska 33 Nig 18001 Serbia

简单液体模型，一个扩大液体模型，和有非局部的电离的液体模型被申请静态的故障电压， Paschen 曲线和当前电压的特征的计算。与为当模特儿的 Paschen 曲线的试验性的数据的最好的协议被与可变第二等的电子产量使用模型完成。当模特儿... 详细信息

简单液体模型，一个扩大液体模型，和有非局部的电离的液体模型被申请静态的故障电压， Paschen 曲线和当前电压的特征的计算。与为当模特儿的 Paschen 曲线的试验性的数据的最好的协议被与可变第二等的电子产量使用模型完成。当模特儿当前电压的特征为不同极间距离被执行，结果与试验性的数据相比。有非局部的电离的液体模型为所有极间距离看一个优秀协议，当有可变电子运输系数的扩大液体模型在短极间距离与大小同意很好时由快电子的电离什么时候能被忽视。

关键词：流体模型辉光放电建模适用性电击穿极间距离电压特性电子产率