Full Factorial Central Composite Design Research Articles

Production of genetically engineered designer biodiesel from yeast lipids

Biodiesels constitute a growing class of fuel in a world that is increasingly inclined towards more ecological and sustainable energy. Despite their many advantages, biodiesels have limited cold flow properties and larger NOX emissions. These limitations are mostly attributed to the chemical compositions of biodiesels which are dictated by the chemical compositions of their feedstock oils. Accordingly, this study presents a novel approach to produce Genetically Engineered Biodiesel (GEB) whose chemical composition can be controlled by the genetic manipulation of oleaginous yeast oils for the production of designer biodiesels with improved properties and performances. Using full-factorial central composite design, the best chemical composition of an optimal biodiesel was predicted. Then, simple and combined MFE1, PEX10 and POX2 mutants of the oleaginous yeast Yarrowia lipolytica were constructed. These mutants showed interesting lipid profiles where their biodiesels are predicted to have better cold flow properties. These mutants showed also higher lipid titers by 2–3 folds compared to the parent strain. This study provides an approach for tailor designing of biodiesel properties and performances via genetic engineering. Moreover, it provides solutions potentially enabling biodiesel to be used as a standalone fuel in cold climates without any mixing with petrodiesel.

Response Surface Methodology Process Optimization of Biodiesel Production from Castor Seed Oil

The increasing demand for energy and the depletion of fossil fuel resources has led to the search for an alternative energy source. The search for such alternative fuel sources has oriented biodiesel synthesis as the ultimate alternative energy resource of the future. The purpose of this study was to produce castor oil and optimize biodiesel production using full factorial central composite design (CCD) through the response surface methodology (RSM) approach. The castor oil was extracted using a mechanical press, and free fatty acids were reduced with acid esterification and biodiesel produced through the transesterification process using homogeneous catalysts. The physicochemical properties of extracted castor oil and biodiesel including density, kinematic viscosity, saponification number, free fatty acid, acid number, cetane number, and iodine number were determined. The ideal conditions for producing biodiesel from castor oil are anticipated to be a reaction period of 105 min at a temperature of 50°C, a catalyst loading weight of 1.5%, and a methanol-to-oil ratio of 5 : 1. The biodiesel yield obtained was 95.0%, and the results of the measured parameters of biodiesel were compared with the international standards of the European norms (EN14214) and the American Society Test Material (ASTM) D6751. The weight composition of both fatty acid and methyl ester was determined by gas chromatography-mass spectroscopy (GC-MS). The study concluded that the results of this research are beneficial in optimizing the parameters for making biodiesel from extracted castor oil.

Application of ozone to enhance the defluoridation property of activated alumina: A novel approach

Drinking water containing high fluoride concentrations may lead to serious health problems. Thus, aiming at water defluoridation through adsorption, several adsorbent materials have been studied worldwide. Due to its low cost and selectivity for fluoride ions, activated alumina (AA) is one of the most applied materials. At the same time, AA has low adsorption capacity, the pH of the aqueous solution must be less than 6.0 for fluoride adsorption, and it requires a long contact time to reach adsorption equilibrium. This study investigated the use of ozone to enhance the defluoridation property of AA. For this purpose, AA was treated under various ozonation conditions. Subsequently, the ozone-treated AA (OAA) samples were applied to adsorb fluoride from an aqueous solution. The influence of some ozonation parameters (AA concentration, pH, and contact time) was evaluated by carrying out adsorption experiments under fixed conditions. As a result, by full-factorial central composite rotational design (CCRD) and response surface methodology (RSM), it was found that the effect of initial pH during the ozonation is negligible on improving the defluoridation property of AA. At the same time, the decrease of AA concentration in the ozonation system significantly enhances the defluoridation property of AA. For example, the ozonation of 10 g L−1 of AA at a pH of 7.0 increased the fluoride removal efficiency of this material from 77.4% to 98.3%. Finally, the analysis of the ozonation time (0–120 min) showed that 90 min are sufficient to promote a significant rise in the fluoride removal efficiency of AA (from 78.3% to 97.4%). AA was characterized by FTIR, SEM, EDX NMR, and N2 physisorption methods to elucidate factors responsible for the increased fluoride removal efficiency when the material is ozonized.

Effect of co-culturing bacteria and microalgae and influence of inoculum ratio during the biological treatment of tannery wastewater

This present investigation is carried out to study the effect of algal and bacterial inoculum concentrations on the removal of organic pollutants and nutrients from the tannery effluent by the combined symbiotic treatment process. The bacterial and microalgal consortia was developed in laboratory setup and mixed together to perform this study. The Influence of algae and bacteria inoculum concentrations on the removal of pollutants such as Chemical Oxygen Demand (COD) and Total Kjeldahl Nitrogen (TKN) were studied using statistical optimization through Response surface methodology. For the design of experimental set up and optimization, full factorial Central composite design was used. The profiles of pH, Dissolved Oxygen (DO) and nitrate were also monitored and studied. The inoculum concentrations of microalgae and bacteria showed significant effect on Co-culturing on COD, TKN and nitrate removals as major response. The linear effect of bacterial inoculum has positive dominant influence on COD and TKN removal efficiencies. Nitrate utilization by microalgae increases with the increase in microalgal inoculum concentration. The maximum removal efficiencies of COD and TKN with 89.9% and 80.9% were obtained at optimum bacterial and algal inoculum concentrations of 6.7 g/L and 8.0 g/L respectively. These outcomes of this study are immensely favorable for maximizing the COD and nitrogen (nutrients) removal capabilities of microalgae-bacterial consortia in tannery effluent.

A new extracellular glutaminase and urease-free L-asparaginase from Meyerozyma guilliermondii.

L-Asparaginase (L-ASNase) is a potent chemotherapeutic drug employed to treat leukemia and lymphoma. Currently, L-ASNases for therapeutic use are obtained from Escherichia coli and Dickeya chrysanthemi (Erwinia chrysanthemi). Despite their therapeutic potential, enzymes from bacteria are subject to inducing immune responses, resulting in a higher number of side effects. Eukaryote producers, such as fungi, may provide therapeutic alternatives through enzymes that induce relatively less toxicity and immune responses. Additional expected benefits from yeast-derived enzymes include higher activity and stability in physiological conditions. This work describes the new potential therapeutic candidate L-ASNase from the yeast Meyerozyma guilliermondii. A statistical approach (full factorial central composite design) was used to optimize L-ASNase production, considering L-asparagine and glucose concentration, pH of the medium, and cultivation time as independent factors. In addition, the crude enzymes were biochemically characterized, in terms of temperature and optimal pH, thermostability, pH stability, and associated glutaminase or urease activities. Our results showed that enzyme production increased after supplementing a pH 4.0 medium with 1.0% L-asparagine and 0.5% glucose during 75h of cultivation. Under these optimized conditions, L-ASNase production reached 26.01 U mL-1, which is suitable for scale-up studies. The produced L-ASNase exhibits maximal activity at 37°C and pH 7.0 and is highly stable under physiological conditions. In addition, M. guilliermondii L-ASNase has no associated glutaminase or urease activities, demonstrating its potential as a promising antineoplastic agent.

Optimization of Xanthan Gum Production by Demerara Sugar Using Response Surface Methodology

Xanthan gum (XG) production using three Xanthomonas sp. strains (290, 472, and S6) was evaluated by applying a 23 full factorial central composite design response to study the interactive effects of the fermentation medium component concentrations as parameters to determine the efficiency of the gum production in batch experiments. The experimental variables were the carbon source (demerara sugar or sucrose), potassium phosphate dibasic, and magnesium sulfate. Experimental results showed the K2HPO4 concentration as the important parameter for XG production by using Xanthomonas axonopodis pv. manihotis IBSBF 290 and X. campestris pv. campestris IBSBF 472, while for the Xanthomonas sp. S6 strain, the MgSO4∙7H2O concentration was the determining factor in XG production using demerara sugar or sucrose as a carbon source. The strains of Xanthomonas 472 and S6, using demerara sugar and higher concentrations of salts, exhibited a higher yield of XG (36 and 32%) than when using sucrose and the same concentration of salts. The experimental outcomes highlighted demerara sugar as a suitable and efficient alternative carbon and micronutrient source for XG production. Despite the bacterial strain influence, the medium composition is crucial for this fermentation process. Therefore, the evaluated salts are important factors for XG production, and the demerara sugar can partially replace this mineral salt requirement as indicated by the face-centered composite experimental design due to its chemical composition. Overall, demerara sugar provides promising properties for XG production.

Design of experiments for the optimization of U(VI) reduction with hydrogen over Pt/SiO2

Abstract Significant amount of uranous nitrate is required for reducing Pu(IV) into inextractable Pu(III) for partitioning of U(VI) and Pu(IV) present in the loaded organic phase in PUREX process. Experiments have been conducted for the preparation of uranous nitrate by reducing uranyl nitrate present in nitric acid solution using hydrogen over Pt/SiO2 catalyst. The effect of process variables such as U(VI) concentration, H2 pressure, nitric acid concentration, catalyst quantity, temperature, mixing speed, and hydrazine concentration (for stabilizing U(IV)) on the yield of U(IV) was studied. The process variables were optimized by a two-step statistical approach namely design of experiments. The initial screening of process variables and determination of important variables that affect the production of U(IV) was determined by definitive screening design (DSD) methodology. The DSD yielded three variables affecting the U(VI) reduction to a significant extent were U(VI) concentration, H2 pressure and mixing speed. These significant variables were further optimized using five-level full factorial central composite design (CCD) methodology for understanding the intricate interactions between the variables and the combined effect of all variables at a time influencing the U(VI) reduction. A second-order polynomial equation derived from CCD was subjected to analysis of variance (ANOVA) for estimating the validity of the model and statistical significance of the terms involved in the polynomial. The results revealed that the model can predict the yield of U(IV) generation with 95% confidence in the proposed experimental range.

Magnetorheological fine finishing of steering rack bar for improving its functional operation

Fine-finished external cylindrical surfaces in automotive manufacturing parts are of great importance for improving their performance. A finely finished external surface of steering rack bar leads to a decrease in its response time. So, in this work, the rotating core-based magnetorheological (MR) finishing process has been performed on the external surface of steering rack bar to improve its performance. In this work, the process parameters have been optimized to fine-finish the current workpiece with minimized efforts. The optimum conditions of process parameters are depicted using full factorial central composite design (CCD) under response surface methodology technique. The maximum contribution to the response, i.e. % change in surface roughness value is found from current (15.28%) and rotational tool speed (8.66%). Using the optimum finishing parameters, the average surface roughness value of the steering rack bar external surface achieved was 30 nm from 550 nm with finishing time of 90 min. Also, the fine finishing of steering rack bar's external surface was confirmed by a comparative study of scanning electron microscopic and mirror images of initial and final finished surfaces conducted in this study. Thus, this study advocated that the current process can be beneficial for fine finishing of industrial components such as rocker arm shafts, vacuum pistons, and cylindrical punches.

Understanding the interactive effects of dietary leucine with isoleucine and valine in the modern commercial broiler

A study was conducted to understand the relationship among dietary branched-chain amino acids (BCAA) on the performance of Ross 344 × 708 male broilers. A total of 2,592 d-old male chicks were randomly placed into 144-floor pens according to a 23 full factorial central composite design (CCD) with 20 treatments (14 treatments and 6 center points). Each treatment consisted of varying digestible Ile:Lys (52 to 75), Val:Lys (64 to 87), and Leu:Lys (110 to 185) ratios. Birds and feed were weighed at 20 and 34 d of age to determine body weight gain (BWG), feed intake, and feed conversion ratio (FCR). At 35 d of age, feather amino acid composition and carcass characteristics were evaluated. Data were analyzed as CCD using the surface response option of JMP v. 15. Body weight gain (1,332 g; P < 0.001; R2 = 0.93) and FCR (1.54; P = 0.002; R2 = 0.88) were optimized at the lowest Leu:Lys ratio (110) with moderate Val:Lys (78 to 79) and Ile:Lys (65 to 66) ratios. Poorer BWG and FCR were observed as Leu:Lys ratio increased while increasing Val:Lys and Ile:Lys ratios alleviated the poor performance. Carcass (71.5%; P = 0.031; R2 = 0.76) and breast yield (26.7%; P < 0.001; R2 = 0.96) were maximized at the highest Leu:Lys ratio. This effect was complemented by increasing Ile:Lys ratio beyond 68. Lower Ile:Lys and Val:Lys ratios were required to maximize carcass and breast yield at the lowest Leu:Lys ratio. However, this strategy yielded less meat than providing a high Leu:Lys ratio diet. Dietary BCAA had little effect on altering the composition of feather protein and amino acid (P > 0.10). These results suggest that optimum BCAA ratios to Lys may vary depending on response criteria and demonstrate the importance of maintaining proper Val and Ile ratios centered on dietary Leu. Live performance can be optimized in diets with low Leu:Lys ratios; however, meat yield can be enhanced by increasing dietary Leu:Lys along with Ile:Lys ratios.

Ultrasound-assisted extraction of saffron bioactive compounds; separation of crocins, picrocrocin, and safranal optimized by artificial bee colony

In this work, a four-factor five-level full factorial central composite design (CCD) was used to optimize the ultrasound-assisted extraction (UAE) of saffron major components, namely picrocrocin, safranal and crocin. The process parameters included ethanol concentration (0–100%), extraction time (2–10 min), duty cycle (0.2–1.0) and ultrasonic amplitude (20–100%). The extracted compounds were measured both by spectrophotometry and chromatography techniques. The results revealed that the middle concentrations of ethanol and relatively long process durations along with high duty cycles and ultrasonic amplitudes had the most profound impact on the yields of the extracted bioactives. UAE was optimized using response surface methodology (RSM) and artificial bee colony (ABC); a comparison between these methods indicated their optimization power was approximately the same. According to the RSM analysis, an ethanol concentration of 58.58%, extraction time of 6.85 min, duty cycle of 0.82 and amplitude of 91.11% were the optimum extraction conditions, while the optimal conditions resulting from ABC were 53.07%, 7.32 min, 0.93 and 100% for the UAE variables respectively. Finally, HPLC analysis was carried out on the UAE optimum extract resulting from RSM. Four crocetin esters were detected in the optimal extract.

Optimization Study of Malachite Green Dye Adsorption by Eggshell Using Response Surface Methodology

Batch adsorption studies for the removal of Malachite green (MG) dye using eggshell was performed. Response Surface Methodology (RSM) was applied to investigate the effect of significant operating parameters on the uptake of the dye molecule. The aim of this study is to determine the potential of eggshell as adsorbent for MG removal and determine the optimum conditions for the adsorption process by using RSM with Central Composite Design (CCD). A 23 full factorial CCD was generated using Design Expert. The effects and interactions of different parameters were evaluated which are contact time (20-60 min), pH (4-8) and adsorbent dosage (0.5-2.0 g). A quadratic model was developed correlating the adsorption variables to the response (percentage of MG removal). Analysis of variance (ANOVA) was used to determine the significant factors on experimental design response. The predicted results obtained were found to be in good agreement (R2 = 0.9388) with the experimental results. The optimum percentage of MG removal was found to be 90.66% with the operating conditions of 40 minutes contact time, pH 6 and 1.25 g of adsorbent dosage. It was suggested that eggshell could be a potential adsorbent in removing MG from aqueous solution.

The Potential Use of Cold-Pressed Pumpkin Seed Oil By-Products in a Low-Fat Salad Dressing: The Effect on Rheological, Microstructural, Recoverable Properties, and Emulsion and Oxidative Stability.

The cold-pressed pumpkin seed oil by-product (POB) was evaluated for its application as a natural fat substitute and stabilizer in the reduced-fat salad dressings. For this aim, the samples were prepared by combining the xanthan gum (0.2–0.4 g/100 g), POB (1.0–5.0 g/100 g), egg yolk powder (3 g/100 g), and sunflower oil (10–30 g/100 g) in 17 different formulations. The optimization was carried out using response surface methodology (RSM) and full factorial central composite design (CCD). Results showed that all samples presented the shear-thinning (or pseudoplastic) flow behavior with 3.75–16.11 Pa·sn and 0.18–0.30, K and n values, respectively. The flow behavior rheological data were fitted to a power-law model (R2 > 0.99). The samples with high POB and low oil content showed similar K and n values compared to high oil content samples. Additionally, the dynamic rheological properties and three interval thixotropic test (3-ITT) were determined. The G′ value was larger than G″ in all frequency ranges, indicating viscoelastic solid characteristics in all samples. The optimum formulation was determined as 0.384% XG, 10% oil, and 3.04% POB. The samples prepared with the optimum formulation (POBLF-SD) were compared to low-fat (LF-SD), and high-fat (HF-SD) control salad dressing samples based on the rheological properties, emulsion stability, oxidative stability, zeta potential, and particle size. The oxidation kinetic parameters namely, IP, Ea, ΔS++, and ΔG++ showed that the oxidative stability of salad dressing samples could be improved by enriched by POB. The results of the present study demonstrated that POB could be considerably utilized as a natural fat substitute and stabilizer in salad dressing type emulsions.

The Effect of Cold Press Chia Seed Oil By-Products on the Rheological, Microstructural, Thermal, and Sensory Properties of Low-Fat Ice Cream.

This study aimed to investigate the utilization of cold-pressed chia-seed oil by-products (CSOB) in a low-fat ice cream formulation as a fat replacer and stabilizer. In the study, ice cream emulsion mixtures were formulated by using 0.2–0.4% xanthan gum (XG), 2.5–12.5% fat, and 1–3% CSOB. Optimization was performed using the response surface methodology (RSM) and full factorial central composite design (CCD) based on the flow behavior rheological properties of the emulsions obtained from 17 different experimental points. All of the emulsion samples showed non-Newtonian shear-thinning flow behavior. The consistency coefficient (Κ) values of the emulsion samples were found to be 4.01–26.05 Pasn and were significantly affected by optimization parameters (p < 0.05). The optimum formulation was determined as 0.29% XG, 2.5% CSOB, 2.5% fat. The low-fat (LF-IC) and full-fat control samples (FF-IC) were compared to samples produced with an optimum formulation (CBLF-IC) based on the steady shear, frequency sweep, and 3-ITT (three interval thixotropy test) rheological properties, thermal properties, emulsion stability, light microscope images, and sensory quality. CBLF-IC showed similar rheological behavior to FF-IC. The mix of CBLF-IC showed higher emulsion stability and lower poly-dispersity index (PDI) value and fat globule diameters than those of FF-IC and LF-IC. The thermal properties of the samples were significantly affected by the addition of CSOB in an ice cream mix. CBLF-IC exhibited a lower temperature range (ΔT), enthalpy of fusion (ΔHf), and freezing point temperature (Tf) than those of FF-IC and LF-IC. While CBLF-IC exhibited a higher overrun value than other samples, it showed similar sensory properties to the FF-IC sample. The results of this study suggested that CSOB could be used successfully in low-fat ice cream production. This study also has the potential to gain new perspectives for the evaluation of CSOB as a fat substitute in a low-fat ice cream.

Multi-response mathematical model for optimization of process parameters in CMT welding of dissimilar thickness AA6061-T6 and AA6082-T6 alloys using RSM-GRA coupled with PCA

The requirement projected by many industries for stronger, lighter, more efficient and cost-effective combined alloys in the welding of two dissimilar materials or dissimilar thickness. The current industry trend is the coalescence of various aluminium alloys of varying thicknesses. In this research paper, Cold Metal Transfer (CMT) welding process was used for the joining of AA6061-T6 and AA6082-T6 using ER4043 filler wire and inspected the effect of different process parameters on mechanical properties of welded butt joints. Current (I), welding speed or travel speed (TS) and gas flow rate (Q) are the input welding process parameters that are to be optimized. Full factorial central composite face-centered design (CCFCD) was utilized to optimize the tensile properties, microhardness and residual stresses. Grey relation analysis (GRA) with PCA is incorporated with CCFCD for finding out the optimal process parameter by considering multi-response parameters simultaneously. ANOVA was executed to interpret the impact of a process parameter on the mechanical properties of the weldments. Results showed that the most dominant process parameter was found to be the welding speed. The optimal process parameter obtained via the GRA-PCA technique is I3-TS1-Q1 (I - 100 A, TS - 5 ​mm/s and Q - 14 ​L/min having heat input 352 ​J/mm) which produces 226 ​MPa of ultimate tensile strength, 12.6% of elongation, 68.7 HV of microhardness and −152.3 ​MPa of compressive residual stress. The desirability of optimality level obtained through CCFD was 65.99% and significantly improved to 97.07 through GRA-PCA.

Synthesis and optimization of a green and efficient sorbent for removal of three heavy metal ions from wastewater samples: kinetic, thermodynamic, and isotherm studies

A novel, green, and stable sorbent (Fe3O4@SiO2@l-Cysteine functionalized magnetic graphene oxide nanocomposites) was synthesized based on a chemical procedure to remove chromium(VI), lead(II), and cadmium(II) ions from wastewater samples. The l-Cysteine functionalized magnetic graphene oxide as a sorbent component was prepared based on the formation of the covalent bonding between graphene oxide and l-Cysteine. The percentages of the sorbent components, including Fe3O4 NPs, SiO2, and C-FGO were optimized using a D-optimal mixture design to enhance the sorbent stability, selectivity, and affinity toward the heavy metal ions. Besides, the critical factors on the heavy metal ion adsorption were investigated and optimized by a two-level full factorial central composite design. Electrostatic attraction is responsible for the adsorption of these ions on the sorbent, which is highly dependent on pH value. The kinetic study shows that the adsorption of these metal ions onto the sorbent follows the pseudo-second-order rate. The experimental results were investigated using the Freundlich and Langmuir models to determine the isotherm model, indicating the Freundlich isotherm model can well describe the adsorption procedure on the sorbent. The maximum adsorption capacity of 476.19, 526.32, and 588.23 mg g−1 was calculated for the Cr(VI), Pb(II), and Cd(II) ions with favorable adsorption and high affinity, respectively. The study of thermodynamic parameters indicates that the adsorption of these ions onto the sorbent is endothermic and chemical in nature. Moreover, the adsorption process is spontaneous in the temperature range of 278–328 K for removing these heavy metal ions. The obtained results confirm that the proposed sorbent is very suitable for the removal of the Cr(VI), Pb(II), and Cd(II) ions from electroplating wastewater samples with many advantages such as high efficiency, environment-friendly, low cost, and short absorption time.

A New Study on Tribological Performance of Cissus Quadrangularis Stem Fiber/Epoxy with Red Mud Filler Composite

ABSTRACT Dry sliding friction and wear behavior, hardness, and thermogravimetric analysis (TGA) of Cissus quadrangularis stem fiber (CQSF)/epoxy resin composite, reinforced with red mud particulate filler were done. The hardness of the material increased by adding red mud filler. Thermogravimetric analysis (TGA) reveals that the maximum char yield obtained at 10 wt.% red mud particulate-filled with CQSF/epoxy composite. The optimization of dry sliding friction and wear behavior was done by response surface methodology (RSM) based on pin-on-disc wear test to determine the specific wear rate (SWR) and coefficient of friction (COF) of the materials. The experimental design was created with four input parameters at three different levels using full factorial central composite design (CCD). The minimum SWR was achieved at 5.93 wt.% red mud addition irrespective of other parameters, was obtained by RSM optimization technique. The scanning electron microscopy (SEM) images of the worn out surfaces substantiate the optimized results of wear properties.

Tribo-Mechanical characterization of carbonized coconut shell micro particle reinforced with Cissus quadrangularis stem fiber/epoxy novel composite for structural application

ABSTRACT In this article, mechanical and tribological characterization of Cissus quadrangularis stem fiber (CQSF)/epoxy resin particulate with and without coconut shell ash (CSA) powder was carried out. The materials were fabricated by the hand lay-up method. Epoxy and 30 wt.% CQSF with 40 mm fiber length were taken to fabricate the base material, and CSA was separately added at 2.5, 5, 7.5, and 10 wt.%. In this way, five materials were fabricated for mechanical and tribological investigation. The tribological characterization was analyzed by Response Surface Methodology (RSM) using Design-Expert software, and pin-on-disc wear testing machine was used to calculate the specific wear rate of the materials under different experimental conditions. A design table was created for four factors and three levels using full factorial central composite design. The maximum tensile (110.31 MPa) and flexural (136.11 MPa) strength obtained at 5 wt.% CSA addition and after that reduced. The maximum hardness (98 HRRW) and impact strength (20.03 J/cm2) were obtained at 10 wt.% CSA particulate-filled CQSF/epoxy composite. CQSF/epoxy with 5.9 wt.% CSA filler yielded better specific wear rate (6.67 × 10−5 mm3/Nm) compared with other compositions, which was found in the RSM technique. Scanning electron microscopy (SEM) images were taken to identify failure mechanisms for the specimen.

Reducing the Non-Recurrent Freeway Congestion with Detour Operations: Case Study in Florida

To alleviate the impacts of freeway incidents and improve the traffic conditions on the entire transportation network, operational systems of discrete facilities need to be coordinated on a corridor. As such, this study focuses on a new traffic diversion methodology for a better utilization of the available traffic capacity of the corridor. The methodology aims to divert incident-induced freeway congestion to the adjacent arterials using the VISSIM microsimulation tool, which can simulate a freeway incident and measure the performance of detour operations. Within the study, an experiment with a 23 full factorial central composite design is utilized in order to define the optimum diversion rate in different demand levels. Experimental results are also modeled with the hierarchical multilevel regression model. Findings indicate that the resultant regression equation can successfully predict the corridor delay with 7 (s/veh) error and 83.85% accuracy. Traffic agencies can employ the proposed hierarchical model to decide whether or not a detour should be implemented. Furthermore, with the estimate of the incident duration and the current V/C ratio on the freeway, the diversion rate that results in a minimum corridor delay can be identified.

Optimization of chlorogenic acid extraction from Elm tree, Ulmus minor Mill., fruits, using response surface methodology

Elm tree, Ulmus minor Mill. belongs to the Ulmaceae family. Some main compounds in this plant are including mucilage, tannins, caffeic acid derivatives, especially chlorogenic acid (CGA) and sterols. Among them, caffeic acid derivatives, especially chlorogenic acid (CGA) with widespread usage in food, cosmetic and pharmaceutical industries, caught our attention and we decided to detect, quantify and finally optimize its extraction from Elm tree, (Ulmus minor Mill.) fruits. Herein, the extraction process was optimized by means of response surface methodology (RSM). Various factors such as temperature, solvent percentage, solid to solvent ratio and extraction time can be effective in an extraction. Screening and selection of important factors was accomplished by 2- level full factorial design and the result of normal probability plot. Based on the results the effect of time was not important and in the next stage of the study using RSM was omitted. In this step, 3-level full factorial central composite rotatable design (CCRD) was used for optimization, in which the temperature, ethanol percent, and solvent ratio were relevant independent variables. Based on the practical results by HPLC and statistical analysis, the optimum conditions for maximum yield was when temperature, solvent to solid ratio and solvent percent were equal to 54.98 °C, 40 (mL/g) and 70% (v/v), respectively, and its desirability function was 0.94.

Optimization of Diesel Biodegrading Conditions Using Response Surface Methodology Based on Central Composite Design

During biodegradation of petroleum products which are the main sources of aromatic compounds, optimization is the major strategy that enhances the performance of the participating organisms. This research aimed at optimizing diesel degrading conditions using the response surface methodology (RSM) based on full factorial central composite design (CCD). Bacteria were isolated from the diesel contaminated soil which were screened based on diesel oil tolerance. Bacteria resting cells (1.5 × 105 cells/ml) of the screened strains were used to formulate consortia using mathematical permutation approach on Bushnell Haas Agar before being tested on heavy metals co-contaminants. Optimization based on CCD was carried out to pH, temperature, salinity, and substrate concentration. The results indicate a total of 47 bacteria were isolated where 4 were finally screened based on their survival at the sole expense of 4% v/v diesel with high growth populations. These bacteria were identified as Alcaligenes sp., Ochrobactrum sp., Alcaligenes aquatilis, and Alcaligenes faecalis UMYU001 (MN519483.1) which were used for the formulation and selection of effective degrading consortium. The selected consortium performed better even in the presence of more than 1 g/L of different heavy metals co-contaminants producing population higher than 1.6 × 104cfu/mL (p-value = 0.0037). Based on the CCD results, parameter values of 7.14 pH, 32 °C temperature, 2.58 g/L NaCl, 3.74% v/v diesel substrate were found to be the optimum conditions for the diesel biodegradation. The interactions among these parameters generated 8.4 × 106cfu/ml which were validated by correlating the predicted and actual experimental results.