Two-level Fractional Factorial Design Research Articles

Design of experiment analysis on tensile properties of PLA samples produced by fused filament fabrication

The fused filament fabrication (FFF) is one of the most common forms of 3D printing with many hobbyists and as well as professional printers adopting this technology. With numerous printing parameters available for each print, having the knowledge to optimize the printing process to obtain a custom mechanical properties is clearly advantageous. This paper aims to analyze the elastic mechanical properties of PLA specimens manufactured through FFF process. To reduce experimental runs, the L27 Taguchi orthogonal array was used to analyze the influence of seven parameters, (i) infill pattern, (ii) layer height, (iii) infill density, (iv) printing velocity, (v) raster orientation, (vi) outline overlap, and (vii) extruder temperature, and three interactions, (i) infill pattern/layer height, (ii) infill pattern/infill density and, (iii) layer height/infill density on both Young’s modulus (E) and yield strength (Rp0.2). To remove any doubt about certain parameters, a two-level fractional factorial design with four factors (24–1) was used to supplement Taguchi approach. Results show that the infill density, infill pattern, printing velocity, and printing orientation are the most influential parameters, whereas layer height, extruder temperature, and outline overlap have no significant influence on Young’s modulus and Yield strength. We show that the analysis of interactions could play a leading role in optimization parameters by removing doubt concerning some parameters. This work could be further developed to propose a model to help designers to obtain either tailor-made or a robust mechanical property with minimum variation and uncertainty in product.

Multiple response optimization of ultrasound-assisted procedure for multi-element determination in Brazilian wine samples by microwave-induced plasma optical emission spectrometry

In the present work, a method was developed, optimized, and validated for the determination of aluminum, manganese, lead, copper, cadmium, and zinc by microwave-induced plasma optical emission spectrometry of wine samples from the São Francisco Valley, northeastern Brazil. The samples were subjected to a sonochemical treatment aiming at the degradation of the sample matrix. To optimize the analytical procedure, initially, a two-level fractional factorial design was used to study five experimental variables and determine which ones significantly affected the analytical response. In a second step, the significant variables were optimized using the Doehlert matrix as the response surface methodology and the desirability function as a strategy to optimize multiple responses. The optimum conditions established were concentrations of nitric acid (2.3 mol L−1) and hydrogen peroxide (9%). The developed method is simple, fast, and precise, has a low operational cost and low limits of detection and quantification. The accuracy confirmed by spike tests with recoveries ranging from 104 to 118% and comparative analysis of the results obtained using the proposed method and digestion total procedure. The method was applied for multi-element determination in three wine samples.

Bioenergy Production through Mono and Co-Digestion of Tomato Residues

The agro-industry of tomato generates three types of residues: ripe rotten tomato (unfit for consumption) (RT), green (unripe) tomato (GT), and tomato branches including leaves and stems (TB). These materials are commonly wasted or used as feed for livestock. Energy production through anaerobic digestion is an alternative way to manage and simultaneously valorise these materials. Initially, the operating conditions of mono anaerobic digestion were investigated using RT. Thus, a design of experiments based on a two-level fractional factorial design with resolution V was performed to determine the factors that affect biochemical methane potential (BMP). The substrate to inoculum ratio (SIR), total volatile solids concentration (VSt), working volume (WV), presence of nutrients (Nu), and the pre-incubation of the inoculum (Inc) were investigated. The results showed that SIR is the most important factor. The maximum BMP for RT was 297 NmLCH4/gVS with SIR = 0.5; tVS = 20 g/L; WV = 20%; no pre-incubation and the presence of nutrients. Using these optimum operating conditions, co-digestion was investigated through a mixture design approach. The substrates RT and GT presented similar BMP values, whereas TB led to a significantly lower BMP. Indeed, when high concentrations of TB were used, a significant decrease in methane production was observed. Nonetheless, the highest BMP was achieved with a mixture of 63% RT + 20% GT + 17% TB, with a production of 324 NmLCH4/gVS, corresponding to a synergetic co-digestion performance index of about 1.20. In general, although the substrate RT generates the highest BMP, the mixture with GT did not impair the methane yield. Overall, the co-digestion of tomato residues must be conducted with SIR close to 0.5 and the content of tomato branches in the reaction mixture should be kept low (up to 20%).

Statistical Optimizing of Medium for Clavulanic Acid Production by Streptomyces clavuligerus Using Response Surface Methodology.

Clavulanic acid (CA) is a naturally occurring antibiotic produced by Streptomyces clavuligerus. Statistical optimization of the fermentation medium for CA production by Streptomyces clavuligerus was carried out. Multiple carbon sources, glycerol, dextrin, and triolein, were considered simultaneously. A two-level fractional factorial design experiment was conducted to identify the significant components of medium on CA production. Statistical analysis of the results showed that soybean meal, dextrin, and triolein were the most significant medium ingredients on CA production. The optimal level of these screened components was obtained by RSM based on the result of a Box-Behnken design, in which the values of dextrin, soybean meal, and triolein in CA fermentation medium were 12.37g/L, 39.75g/L, and 26.98ml/L, respectively. Using the proposed optimized medium, the model predicted 938mg/L of CA level and via experimental rechecking the model, 946mg/L of CA level was attained in shake flask fermentation, significantly high than 630mg/L of original medium. The optimized medium was further verified in 50-L stirred fermenter, and compared with performance of original medium in parallel, CA titer was increased from 889 to 1310mg/L; a 47% increase was achieved through medium optimization by statistical approaches.

Ultrasonic-assisted dispersive liquid–liquid microextraction (US DLLME) of zinc in Brazilian sugarcane spirit samples

A method based on the dispersive liquid–liquid microextraction for the pre-concentration of zinc in samples of Brazilian cachaca and determination by flame atomic absorption spectrometry (FAAS) was developed. The procedure is based on the injection of a mixture composed of carbon tetrachloride (extractor) and 5-(4-dimethylaminobenzylidene) rhodamine (complexing) in cachaca samples. The composition of the components of microextraction was univariable optimized. Posteriorly, a two-level fractional factorial design (26−2) was performed to evaluate the significance of the variables, pH, buffer concentration, centrifugation time, sonication time, NaCl concentration and temperature. Analysis of the Pareto graph showed that the pH, NaCl concentration and sonication time are statistically significant. These variables were optimized using the Doehlert matrix, which was obtained as better experimental conditions: pH, 9.0; %NaCl, 4% (m v−1); sonication time, 5.5 min. The precision expressed as relative standard deviation (RSD) was 3.43% for 20 μg L−1, the limit of detection was 0.11 μg L−1, and the limit of quantification was 0.33 μg L−1. The pre-concentration factor of the method was 28. The method was applied for the analysis of Brazilian sugarcane spirit, and the concentration of zinc ranged from 1.35 to 12.5 μg L−1.

Innovative Quality by Design Approach for Development of Green Micellar HPLC Method for Simultaneous Determination of Atorvastatin and Amlodipine

The combined implementation of quality by design principles and green analytical chemistry leads to development of green micellar HPLC method for analysis of atorvastatin calcium and amlodipine besylate in binary mixtures and in their tablet dosage forms within 8 min. A two-level fractional factorial design was implemented for screening of different method parameters affecting chromatographic responses. Box–Behnken design was then used to study and optimize the most critical parameters. The optimum chromatographic conditions obtained from Box–Behnken design involved the use of a mixture of 0.17 M sodium dodecyl sulfate solution adjusted to pH 2.9 and 10%v/v n-butanol as mobile phase at a flow rate of 1.5 mL min−1 and column temperature kept at 45 oC. The stationary phase was X-Bridge™ (150 mm × 4.6 mm, 5 μm) column. The fluorescence detection was programmed at 276/378 nm (excitation/ emission) for the first 5 mins for atorvastatin then switched to 366/442 nm (excitation/emission) for amlodipine. A linear response was obtained over the ranges of 0.2–25 μg mL−1 for both drugs. The proposed method was validated and successfully implemented for the simultaneous determination of cited drugs in their different tablet dosage forms. The method was additionally applied to content uniformity testing according to the official guidelines. The application of quality by design principles and green analytical chemistry results in development of robust green method with less trial and error experiments.

Effect of Processing Parameters on the Diameter and Morphology of Electrospun Iron-Modified Montmorillonite (Fe-MMT)/Polycaprolactone Nanofibers

Iron-modified montmorillonite-filled polycaprolactone nanofiber mats were produced via electrospinning with varying applied voltage, flow rate, needle-tip-to-collector distance, and needle diameter. Scanning electron microscopy (SEM) was used to observe fiber morphology and characteristics. The effects of varying process parameters on various fiber characteristics were evaluated using a two-level fractional factorial experimental design. The effect of voltage on fiber diameter differed with varying flow rate. At 32 ml/hr, the average fiber diameter decreased from 518.38 nm ± 289.37 nm to 466.43 nm ± 312.36 nm when the voltage is increased. At 42 ml/hr the effect of voltage on fiber diameter was reversed. The average fiber diameter was also found to decrease from 516.03 nm ± 283.48 nm to 467.96 nm ± 318.07 nm with decreasing tip-to-collector distance at 32 mL/hr flow rate. The variation of the effect of the factors on fiber diameter was mainly due to a significant loss of material observed at 12 kV and 15 cm tip-to-collector distance. Bead formation was observed for all runs with more beads being formed at 12 kV applied voltage and 15 cm tip-to-collector distance. Spherical beads were observed at 12 kV and 15 cm tip-to-collector distance while spindle-like beads were present in nanofiber membranes spun at high voltage and at the combination of low voltage and low tip-to-collector distance. The parameter setting combination of 19 kV, 32 ml/hr flow rate, 10 cm tip-to-collector distance, and 0.514 mm needle diameter yielded the lowest fiber diameter with the least amount of beading and small bead size. Small fiber diameters and less beading provide larger surface area and more exposure of the Fe-MMT particles for more efficient adsorption.

Microbial activity in peat-reduced plant growing media: Identifying influential growing medium constituents and physicochemical properties using fractional factorial design of experiments

The development of peat-reduced plant growing media for horticulture is needed to tackle sustainability concerns related to the peat production process. Alternative growing media constituents with unique physicochemical properties, like coir pith, wood fiber, compost, and inorganic materials are currently used. However, little is known about the impact of these materials on microbial activity. Because microbial communities play an important role in plant growth and development, the impact of various growing media constituents on microbial activity was analyzed using two-level fractional factorial statistical design of experiments. The results showed that growing media composition greatly affected microbial activity. White peat (+2.4% CO2) and composted bark (+1.5% CO2) significantly promoted microbial activity over black peat and green waste compost respectively. In contrast, the organic materials coir pith and wood fiber, as well as the inorganic materials perlite and sand, had little effect on microbial activity. Physicochemical analysis of the different growing media mixtures revealed that the water-filled porosity (WFP) was the most important parameter driving microbial growth, increasing microbial activity (+2.1% CO2) at 62.95% WFP compared to 82.95% WFP. Our results are instrumental for developing novel organic growing media with distinct microbial features to move towards a low peat sustainable horticulture.

Quantifying the sources of uncertainty when calculating the limiting flux in secondary settling tanks using iCFD.

Solids-flux theory (SFT) and state-point analysis (SPA) are used for the design, operation and control of secondary settling tanks (SSTs). The objectives of this study were to assess uncertainties, propagating from flow and solids loading boundary conditions as well as compression settling behaviour to the calculation of the limiting flux (JL) and the limiting solids concentration (XL). The interpreted computational fluid dynamics (iCFD) simulation model was used to predict one-dimensional local concentrations and limiting solids fluxes as a function of loading and design boundary conditions. A two-level fractional factorial design of experiments was used to infer the relative significance of factors unaccounted for in conventional SPA. To move away from using semi-arbitrary safety factors, a systematic approach was proposed to calculate the maximum SST capacity by employing a factor of 23% and a regression meta-model to correct values of JL and XL, respectively - critical for abating hydraulic effects under wet-weather flow conditions.

Extraction of silver from a refractory silver ore by sono-cyanidation.

In this study, effect of ultrasound on silver extraction from a refractory silver ore containing both native silver and various silver sulphide minerals was investigated. Main effects and interaction effects of pulp density, ultrasonic frequency, cyanide concentration, air flow rate and agitation speed on the extraction rate of silver were studied by a two-level fractional factorial experimental design. A few additional cyanidation tests were also conducted to verify the findings of the designed experiments. It was found that the overall extraction yield was varied from 67% to 90% depending on the operating conditions used in the sono-cyanidation tests (48h). However, it was varied from 63% to 80% by same operating conditions used in the direct cyanidation tests at the same cyanidation time. It was observed that an increase in the ultrasonic frequency has a negligible effect on the silver recovery. More importantly, it was determined that there were insignificant differences between the 24-h sono-cyanidation results and the 48-h direct cyanidation results for each cyanidation conditions. This finding, which is very important from the cyanidation practice standpoint, indicates that the cyanidation time can be reduced up to 50%, or the capacity of an operating silver extraction plant can be increased up to 100% by the sono-cyanidation by the refractory silver ores. In order to describe the rate of silver dissolution in the cyanide solutions, the experimental data were analysed using shrinking core models. It was found that there is a good fit between the experimental data and the models, indicating the rate of silver dissolution in cyanide can be described by a two-stage, porous layer diffusion controlled, shrinking core model.

Use of Nano-TiO2 self-assembled flax fiber as a new initiative for immiscible oil/water separation

In this study, an environmental friendly, reusable and low-cost functionalized flax fiber was fabricated to separate immiscible oil and water. Flax fibers were modified by plasma-induced poly(acrylic acid) (PAA) polymerization followed by nano-TiO2 self-assembly. A two-level fractional factorial design was engaged to analyze the modification influencing parameters and their interactions. The modified fiber was comprehensively characterized by synchrotron-based Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF). For the first time, the concentration distribution of functional groups and TiO2 nanoparticles (TiO2 NPs) were explored on flax fiber surface. The TiO2 NPs were found unevenly fixed on flax fiber surface with high concentration on abundant substrate. The hydrophilicity of nano-TiO2 self-assembled flax fiber was significantly improved, with water contact angle decreasing from 97.4° to 25.9° and almost doubled maximum oil holding pressure. The modified flax fiber showed stable performance of oil/water separation in alkaline and salty conditions and could be used for multiple cycles. The modified flax fiber could be further constructed into oil barrier with special wettability to separate oil.

SCREENING OF FACTORS INFLUENCING EXO-POLYGALACTURONASE PRODUCTION BY ASPERGILLUS NIGER ATCC 120120 USING TWO-LEVEL FRACTIONAL FACTORIAL DESIGN

Exo-polygalacturonase was produced by Aspergillus niger ATCC 120120 in a solid-state fermentation using Nephrolepis biserrata leaves. Factors affecting the production of exo-polygalacturonase were determined using a two-level fractional factorial design. The screening process for six factors; pH, incubation time, temperature, pectin concentration, inoculum size and moisture content, that influence the production of exo-polygalacturonase by A. niger was performed. The result of variance analysis (ANOVA) suggested that there were four statistically significant (P < 0.005) factors in the production of exo-polygalacturonase by A. niger. These factors were incubation time, temperature, pectin concentration and moisture content. The statistical analysis shows that the linear mathematical model is significant with coefficient of determination (R2) value of 0.9711. The optimum production of exo-polygalacturonase obtained using the model in this study was at 40.00 U/g.

Numerical optimization of probiotic Ayran production based on whey containing transglutaminase and Aloe vera gel.

The purpose of this study was to optimize the functional properties of probiotic Ayran. Two-level fractional factorial design with four center points was used to investigate the effect of five independent variables including, reconstructed whey protein (70-90% of milk), salt (0.5-1g/100g), Aloe vera gel (0-30g/100g), transglutaminase enzyme (0-14 unit/100g) and storage time (1-21days). The viability of Lactobacillus acidophilus La-5 and other physicochemical properties such as pH, acidity, viscosity, sedimentation, and color were modeled and then optimized using desirability function method. Results showed that reconstructed whey protein and Aloe vera gel significantly affected the viability of L. acidophilus La-5 and other physicochemical properties (p < 0.05). The viability of L. acidophilus La-5 and viscosity decreased by increasing of whey protein percentage from 70 to 90. Maximum L. acidophilus La-5 count was observed in samples with a minimum level of whey protein and maximum level of Aloe vera gel. Milk replacement with whey protein up to 90% caused to decrease acidity and viscosity significantly but sedimentation increased (p < 0.05). Optimum condition for production of functional Ayran determined as follow: Aloe vera gel concentration: 25.7%, reconstructed whey protein: 70%, salt: 0.58% and transglutaminase enzyme: 5 unit/100mL.

Valorization of Nutraceutical Industrial Coriander Seed Spent by the Process of Sustainable Adsorption System of Acid Black 52 from Aqueous Solution

The potential usage of coriander seed spent which is a nutraceutical industrial by-product in the removal of Acid Black 52 (AB52) dye from aqueous solutions was evaluated with respect to various experimental parameters including pH, initial dye concentration, adsorbent dosage, adsorbent particle size, duration of contact time and temperature. The optimal qe value at pH 2, pH 7 and pH 12 was 432 mg g−1, 164 mg g−1 and 220 mg g−1, respectively. Two-level fractional factorial experimental design model yielded maximum adsorption value of 867.00 mg g−1. The influence of each parameter and combination of parameters on the final adsorption capacity of the system has been shown by analysis of variance (ANOVA). Equilibrium data were analyzed by four two-parameter and five three-parameter isotherm models. The dye uptake obeyed pseudo-second order kinetic expression. Intra-particle diffusion showed that the adsorption mechanism was more governed by external mass transfer. AB52 dye adsorption on nutraceutical industrial coriander seed spent (NICSS) was endothermic and almost spontaneous. The NICSS has a highly fibrous matrix with hierarchical porous structure as evidenced by SEM images. The FTIR analysis of the spent confirmed the presence of cellulosic and ligno-cellulosic matter imparting both hydrophilic and hydrophobic properties. The results proved that NICSS efficiently removes AB52 dye from water and textile industrial effluent. For the aforesaid reasons; we believe, the readership of the journal will be most interested in: It is envisaged that NIS as new class of biosorbent will foster innovation and provide competitive edge over reported agriculture waste.

Evaluation and improvement of promising rubber recycling OT machine using fractional factorial and response surface design

A design of experiment (DOE) is used in many industrial sectors in the development and optimization of manufacturing processes. DOE is a more effective way to determine the impact of two or more factors on a response. In this paper, a Two-Level Fractional Factorial design was employed to develop the important factors that significantly affect new promising OT Rubber recycling machine using a DOEs analysis. Central composite design (CCD) and response surface methodology (RSM) were used to optimize the isolating screen size. The CCD considered five factors with two-level full factorial design. CCD experiments using RSM was proved to be an optimal tool for optimization.

Development of sustainable acid blue 113 dye adsorption system using nutraceutical industrial Tribulus terrestris spent

First-ever study was done using a low-cost Tribulus terrestris spent, a by-product of a nutraceutical industry as an effective biosorbent for removing acid blue 113 (AB113) from aqueous media. The effect of various factors such as pH, dye concentration, amount of adsorbent, particle size of adsorbent, contact time as also temperature on adsorption have been studied. Analysis of equilibrium data was done by using two number of two-parameter and six number of three-parameter isotherm models. Kinetic studies on adsorption were done using models like pseudo-first order and pseudo-second order. Webber–Morris and Dumwald–Wagner diffusion models helped to study diffusion. Determination and evaluation were also done for change in enthalpy (ΔH°), entropy (ΔS°), and Gibbs free energy (ΔG°) of adsorption system. Scanning electron microscopy, Fourier transform infrared spectroscopy and determination of point of zero-charge were carried out for surface characterization of the adsorbent. We have used a two-level fractional factorial experimental design approach and subsequently analysis of variance to define a statistically developed model from which we obtained values of above parameters which yielded maximum possible adsorption as 93.00 mg/g. The investigations proved that nutraceutical industrial T. terrestris spent is both cost-effective and an efficient biosorbent for the remediation of AB113 dye from aqueous system and textile industrial effluent.

Design of Prototype Formulations for In Vitro Dermal Delivery of the Natural Antioxidant Ferulic Acid Based on Ethosomal Colloidal Systems

Ferulic acid (FA), a naturally occurring antioxidant, is currently used to prevent skin damage. However, FA is very unstable upon exposure to UV radiation and other factors, which decrease its shelf-life and effectiveness. Therefore, in this work, different prototypes of ethosomal FA vesicular systems were designed and developed to provide protection against different environmental factors. A two-level fractional factorial design was employed using particle size, zeta potential (ZP), incorporation efficiency (EE), polydispersity index (PDI), and the existing relationship between length and width of vesicles or aspect ratio (AR) as response variables. The optimal formulation was characterized using differential scanning calorimetry (DSC), infrared analysis, UV-Vis absorption, in-vitro permeability, and thermal degradation studies. Depending on the processing conditions, the EE and particle size varied between 3 and 87% and 470 and 1208 nm, respectively. Membrane studies indicated that the free product released ~4.8% of the compound, whereas the encapsulated material released ~7.1%. Because of their enhanced permeability, ethosomes could be a promising alternative for the topical administration of antioxidants to reduce the oxidative damage caused by solar radiation.

Exploring the Nano Spray-Drying Technology as an Innovative Manufacturing Method for Solid Lipid Nanoparticle Dry Powders.

To take advantage of solid-state properties, the nano spray-drying (NSD) technique was investigated as an innovative one-step method to produce solid lipid nanoparticles (SLN) in the form of a dry powder starting from a lipid/leucine O/W emulsion. Compritol was chosen as wall-forming lipid. Rapamycin (Rp) was employed as a model drug to be loaded into SLN. Based on an initial screening, Lutrol F68 was chosen as surfactant and high-shear homogenization as an emulsification method. A two-level fractional factorial design and an extended factorial design were employed to determine critical factors and best preparation conditions. Compritol concentration, L-leucine/lipid ratio, and Lutrol F68 concentration resulted critical. Best conditions granted 51% yield, 3.2μm L-leucine/SLN particle size, and a SLN population around 150nm. All samples showed the presence of lipid aggregates. Material loss in the emulsification step was found responsible for SLN aggregation and low yield. The almost quantitative Rp loading increased SLN population span. Replacing compritol with cetyl palmitate produced aggregation of dry powders and SLN. Overall, NSD was found a fast method to produce SLN dry powders. More insightful assessment of the emulsification step and lipid property effects will be critical to the optimization of the NSD process. Hypotheses account for direct coupling of high-pressure homogenization with NSD for future successful development of this promising manufacturing method.

The use of factorial design in screening of factors influencing hexavalent chromium extraction by continuous green emulsion liquid membrane

Recently, increasing concerns on hexavalent chromium as an environmental pollutant can be observed due to its build-up to toxic levels in the environment, resulting from various industrial and agricultural activities such as electroplating, stainless steel production, leather tanning and textile manufacturing. This work screens the significant factors that largely affect the efficiency of hexavalent chromium (Cr(VI)) removal from electroplating wastewater in continuous green emulsion liquid membrane using fractional factorial design. There are six factors investigated for affecting the removal of chromium which are residence time (t), TOMAC concentration (M), stripping agent concentration (M), rotational speed (rpm), treat ratio, and modifier concentration (w/v). The response variable of the chromium removal was identified using the two-level fractional factorial (two level) design and the results were analyzed statistically. Five factors were identified to have significant influence on chromium removal which are retention time, rotational speed, treat ratio, modifier concentration and carrier concentration. Regression models for chromium extraction were developed and the adequacy of the model was examined. The results of this study indicate that fractional factorial design is capable to predict the significant factors affecting hexavalent chromium extraction by using continuous green emulsion liquid membrane.

Culture Medium Optimization for Production of Rhamnolipids by Burkholderia glumae

Burkholderia glumae is a biosafety level 1 bacterium capable of producing rhamnolipid biosurfactant with longer 3-hydroxy fatty acid chains moieties than those produced by the prototypal producer, the opportunistic pathogen Pseudomonas aeruginosa. Although the capacity of production of rhamnolipid, and the parameters affecting this production, are well established for P. aeruginosa, little is known about the factors that may affect their production in B. glumae. Hence, to evaluate and enhance the production of rhamnolipids in B. glumae, following the selection of best carbon and nitrogen sources, a two-level fractional factorial design experiment was performed to identify the limiting factors significantly affecting the production of rhamnolipids in this bacterial species. Effects of six inorganic nutrients and two physical parameters were studied, and mannitol, urea, CaCl2, and potassium phosphate buffer were selected for further optimization by applying a response surface methodology (RSM). Under the identified optimized conditions, a rhamnolipid production of 1.66 g/L was obtained, about five times higher than that of the initial non-optimized conditions. This represents a key step in the development of large-scale production processes.