Application Of Response Surface Methodology Research Articles

Gyrotactic Motile Microorganisms Impact on Pseudoplastic Nanofluid Flow over a Moving Riga Surface with Exponential Heat Flux

Background: The improvement of the thermal conductivity of nanofluids is practical for different processes such as drug delivery, manufacturing of crystals, polymer processing, food and drink, cancer treatment, oil and gas, paper making and for many more. The bioconvection phenomenon has engrossed the attention of numerous researchers for its many applications in biotechnology, mechanical and electrical engineering. Bioconvection nanofluids are more prominent in the fields of biomedicine, pharmacy, nanodrug delivery, biomedical, automotive cooling and the military. Purpose: The major purpose of the current work was to determine the numerical and statistical analysis of a novel thermal radiation and exponential space-based heat source on the bioconvective flow of a pseudoplastic 3D nanofluid past a bidirectional stretched Riga surface. The behavior of the Arrhenius activation energy (AAE) and thermal radiation are also disclosed. Methodology: Suitable similarity transformations were used to transmute the partial differential equations of the flow-modeled phenomena into the structure of ordinary differential ones. The numerical solutions for the renewed set of ODEs were tackled by the bvp4c shooting algorithm built-in MATLAB software. Furthermore, the statistical analysis was computed by applying response surface methodology (RSM). Research implications: The numerical analysis is valid for the incompressible three-dimensional, magnetized flow of a pseudoplastic bioconvection nanofluid through a bidirectional surface with Riga plate aspects in the occurrence of activation energy. Social implications: The flow across three dimensions has quite important implementations in various fields, for example, polymer production, material production technology, the manufacturing of nano-biopolymer computer graphics, industry, powered engineering, aeroplane configurations, etc. The current analysis is more applicable in nanotechnology. Results: The consequences of flow control parameters over flow profiles were studied and explained under the graphic structures. Numerical outcomes were computed and discussed in detail. From the results, it was noted that the velocity field was increased via a larger mixed convection parameter. The temperature distribution was boosted via the thermal Biot number. The concentration of nanoparticles declined via the greater Lewis number. Furthermore, the motile microorganisms field was reduced via the Peclet number. Originality: Until now, no investigation has been recognized to examine the consequences of the bioconvection flow of three-dimensional pseudoplastic nanofluids past a Riga plate containing motile microorganisms utilizing the shooting method called bvp4c. Conclusions: From the results, it was concluded that nanofluids are more helpful for heat transfer increments. Furthermore, from the experimental design observed, the response declined via the thermophoresis parameter, which was significant from the ANOVA observed model.

Optimization of CO2/H2 Separation over Ba-SAPO-34 Zeolite Membrane Synthesized by Microwave Heating.

CO2/H2 separation using membrane technology is an important research area in order to obtain high purity hydrogen as one source of clean energy. Finding a suitable inorganic membrane is one of the critical issues, which needs to be explored for CO2/H2 separation. In the present study, Ba-SAPO-34 zeolite membrane was synthesized and followed by a modification process. CO2/H2 separation of the membrane was investigated by varying the independent process variables (CO2 % in the feed, pressure difference across the membrane and temperature). Modeling and optimization for the responses (CO2/H2 separation selectivity and CO2 permeance) was performed by applying response surface methodology and central composite design, which is available in Design Expert software. The accuracy of the models in predicting the response was tested by comparing with the experimental value of response and the two values were in good agreement. The optimization of the models gave CO2 permeance of 19.23 × 10−7 mol/m2 s Pa and CO2/H2 separation selectivity of 11.6 at 5% CO2 in the feed, a pressure difference of 100 kPa, and temperature of 30 °C for Ba-SAPO-34 zeolite membrane.

Study of machining parameters in reciprocating magnetorheological polishing process based on response surface methodology

PurposeThis paper aims to analyze the significance of machining parameters (workpiece’s rotational speed, magnet coil current and working gap) on final Ra (surface roughness) and material removal rate (MRR) of workpiece in reciprocating magnetorheological polishing (RMRP) process.Design/methodology/approachThe research is planned to analyze, model and predict the optimum machining parameters to anticipate final Ra and MRR by applying response surface methodology (RSM) and multiresponse optimization (desirability function approach). The experiments have been planned by design of experiments (DOE). Analysis of variance (ANOVA) is applied to determine the significances of machining parameters on RMRP performance characteristics.FindingsResponse surface plots for final Ra and MRR by RSM show that machining parameters are significant for the responses. The optimum machining parameters obtained are optimized by desirability function approach (DFA), and the optimum parametric combination has been validated by confirmatory experiments. The experimental results of the final Ra and MRR are deviated by 5.12% and 2.31% from the response results under the same optimization conditions, respectively.Originality/valueIn this study, the RMRP responses (final Ra and MRR) are improved at predicted input machining parameters condition obtained by RSM and DFA approach. Furthermore, the research results provide a reference for experimental design and optimization of MRP process.

Nutritional Evaluation of Sea Buckthorn “Hippophae rhamnoides” Berries and the Pharmaceutical Potential of the Fermented Juice

Sea buckthorn is a temperate bush plant native to Asian and European countries, explored across the world in traditional medicine to treat various diseases due to the presence of an exceptionally high content of phenolics, flavonoids and antioxidants. In addition to the evaluation of nutrients and active compounds, the focus of the present work was to assess the optimal levels for L. plantarum RM1 growth by applying response surface methodology (RSM), and to determine the impact of juice fermentation on antioxidant, anti-hypertension and anticancer activity, as well as on organoleptic properties. Sea buckthorn berries were shown to contain good fiber content (6.55%, 25 DV%), high quality of protein (3.12%, 6.24 DV%) containing: histidine, valine, threonine, leucine and lysine (with AAS 24.32, 23.66, 23.09, 23.05 and 21.71%, respectively), and 4.45% sugar that provides only 79 calories. Potassium was shown to be the abundant mineral content (793.43%, 22.66 DV), followed by copper and phosphorus (21.81 and 11.07 DV%, respectively). Sea buckthorn juice exhibited a rich phenolic, flavonoid and carotenoid content (283.58, 118.42 and 6.5 mg/g, respectively), in addition to a high content of vitamin C (322.33 mg/g). The HPLC profile indicated that benzoic acid is the dominant phenolic compound in sea buckthorn berries (3825.90 mg/kg). Antioxidant potentials (DPPH and ABTS) of sea buckthorn showed higher inhibition than ascorbic acid. Antimicrobial potentials were most pronounced against Escherichia coli BA12296 (17.46 mm). The probiotic growth was 8.5 log cfu/mL, with juice concentration, inoculum size and temperature as the main contributors to probiotic growth with a 95% confidence level. Fermentation of sea buckthorn juice with L. plantarum RM1 enhanced the functional phenolic and flavonoid content, as well as antioxidant and antimicrobial activities. The fermentation with L. plantarum RM1 enhanced the anti-hypertension and anticancer properties of the sea buckthorn juice and gained consumers’ sensorial overall acceptance.

Leaching of yttrium and europium from fluorescent lamp phosphor powder using nitric acid: kinetics and optimization

ABSTRACT Rare earth elements (REEs) are recognized as one of the most critical elements and considered essential for the development of sustainable energy technologies, lasers, electronics, alloys, catalysts, and other applications. In order to meet the increasing demand to ensure those essential usages, the supply of REEs is however limited from the primary sources. Recovery of REEs from secondary resources, such as discarded electrical and electronic equipment, referred to as electronic waste (e-waste) is consequently crucial. Fluorescent lamps among such wastes are of special concern due to the high quantity of REEs present in them. This article discusses a potential hydrometallurgical method for recovering REEs (yttrium and europium) from fluorescent lamp waste via nitric acid leaching. The effects of leaching factors including acid concentration and temperature were examined. To assist the leaching yields of those metals, the effect of alkaline fusion was specifically examined. The kinetics of both processes, direct- and alkaline fusion-assisted leaching were investigated based on the shrinking core model. In the case of direct leaching, the metal dissolution was controlled by surface chemical reaction with apparent activation energies of 43.9 and 48.1 kJ/mol for yttrium and europium, respectively, in the temperature range 303–333 K. Pretreatment, viz., the alkaline fusion changed the subsequent leaching mechanism to diffusion control with apparent activation energies of 7.4 and 9.5 kJ/mol for the respective metal in the same temperature range. Optimization of the alkaline fusion-assisted acid leaching process was undertaken by applying response surface methodology (RSM) based on the central composite design (CCD). Under the alkaline fusion conditions such as soda/fluorescent powder mass ratio of 0.65 g/g, temperature of 1223 K and reaction time of 7200 s followed by acid leaching (nitric acid concentration – 3.5 M, temperature-323 K, pulp density – 30 g/L and leaching duration – 1200 s), the leaching efficiencies of 92.6% and 99.5% for yttrium and europium, respectively, could be achieved.

Response Surface Methodology Based Development and Quantification of Celecoxib and Amlodipine Using RP-HPLC.

A novel RP-HPLC method for estimation of Amlodipine Besylate and Celecoxib using an experimental design approach employing response surface technique was developed and validated using a C18 column and its application in marketed formulation. A multivariate optimization of experimental conditions was carried out using experimental design employing organic content in the mobile phase, pH, and flow rate of the mobile phase as three independent variables. The aim of the study was to apply response surface methodology and to study the effect of the independent variables on separation and estimation of both drugs by RP-HPLC method using faced central composite (FCC) experimental design which is novel in this area of research. Optimization of retention time of the last eluting peak and peak symmetry was performed using Derringer’s desirability function in which potassium dihydrogen phosphate buffer with pH 4. 45, 25 mM, 0.5% Triethylamine and acetonitrile in an isocratic proportion of 70:30% v/v and 1.2 ml/min flow rate was found to be the predicted optimum condition. DoE approach based RP-HPLC method development using response surface methodology led to efficient separation with a lower retention time of eluted peaks below 7 min indicating novelty of research. A linear response was observed over the concentration range of 40-240 μg/mL for Celecoxib and 1-6 μg/ mL for Amlodipine Besylate. Limit of detection (LOD) and limit of quantitation (LOQ) for Celecoxib were found to be 0.02 μg/mL and 0.08μg/mL, and for Amlodipine Besylate were 0.0053 μg/mL and 0.0162 μg/mL, respectively. The method was successfully validated in accordance with ICH guideline acceptance criteria for linearity, accuracy, precision, specificity, robustness.

Modeling and optimizing Cd(II) ions adsorption onto Corn Silk/Zeolite-Y composite from industrial effluents applying response surface methodology: isotherm, kinetic, and reusability studies

Modeling and optimizing Cd(II) ions adsorption onto Corn Silk/Zeolite-Y composite from industrial effluents applying response surface methodology: isotherm, kinetic, and reusability studies

Purification of Aspergillus tamarii mycelial fructosyltransferase (m-FTase), optimized FOS production, and evaluation of its anticancer potential.

In the present study, generation of prebiotic fructooligosaccharides (FOS) using Aspergillus tamarii FTase was optimized by applying response surface methodology. Optimal FOS (251g L-1 ) was generated at 28.4°C, pH 7.0 and 50% (w/v) sucrose leading to 1.97-fold yield enhancement. The m-FTase was purified using ultrafiltration followed by HiTrap Q HP anion exchange chromatography resulting in 2.15-fold purified FTase with 12.76 U mg-1 specific activity. Purified FTase (75kDa) had Km and Vmax values of 1049.717mM and 2.094µmol min-1 mg-1 , respectively. FOS incorporation led to upregulation of caspase 3, caspase 9, and Bax genes suggesting mitochondrial apoptosis activation in cancer cells. The study describes characteristics of purified FTase from A. tamarii, production optimization of FOS and unravels the role of FOS in anticancer activity against HT-29 cells. PRACTICAL APPLICATION: This study provides detailed insights of kinetic and thermodynamic characteristics of purified FTase, a prebiotic FOS-generating enzyme. Moreover, the role of the apoptotic genes involved in anticancer activity, and the prebiotic potential of FOS is also investigated. These findings are important in the context of FOS applications, and the optimized production strategies make it useful for industrial application.

Optimization of carbon nanotube growth via response surface methodology for Fischer-Tropsch synthesis over Fe/CNT catalyst

Light olefins such as ethylene, propylene, and butylene are key compounds in the chemical industry. Iron catalyst supported on carbon nanotubes (CNTs) is an appropriate candidate for light olefins production using synthesis gas in Fischer-Tropsch synthesis (FTS). First, catalytic chemical vapor deposition (CCVD) method was applied to synthesize CNTs using Fe/CaCO3 and acetylene as catalyst and hydrocarbon source, respectively. Applying response surface methodology, the optimum operating conditions were determined in CVD reactor for maximal yield and purity of CNTs. The effects of reaction time (30–60 min), reaction temperature (700–800 °C), and loading of the catalyst (10–30 wt% Fe) were investigated. The synthesized CNTs was characterized by Raman spectroscopy for its graphitic structure and purity. After acid-treatment of the synthesized CNTs, Fe/CNTs-synthesized catalyst was successfully fabricated by ultrasonic-assisted wet impregnation method. 20Fe/CNTs-synthesized, 20Fe/CNTs-commercial, and 20Fe/Al2O3 were analyzed in terms of physio-chemical properties and FTS catalytic performance. Comparison of transmission electron microscopy (TEM) and CO-chemisorption results showed that 20Fe/CNTs-synthesized reduces iron oxide agglomeration resulting in metal particles well-dispersed among the studied Fe-based catalysts. The catalytic performance of Fe-based catalysts was investigated using a fixed-bed reactor at 280 °C under 290 psi. 20Fe/CNTs-synthesized exhibited a lower rate of water-gas-shift (WGS) reaction compared with 20Fe/CNTs-commercial, with C2-C4 selectivity of 23.6% which is slightly less than that of its commercial counterpart. Analysis of FTS liquid products revealed that 20Fe/CNTs-synthesized provides liquid hydrocarbons in the range of C8-C18, while 20Fe/CNTs-commercial and 20Fe/Al2O3 obtained C9-C52 and C10-C20, respectively. After 120 h time on stream under steady state condition, higher activity had been maintained by the 20Fe/CNTs-synthesized catalyst compared to the 20Fe/CNTs-Commercial and 20Fe/Al2O3 catalysts.

Coaxiality error analysis and optimization of cylindrical parts of CNC turning process

High precision rotary shafts with precise geometrical tolerances are generally mounted with a micron level clearance between the gears and casing during operation in industrial applications. Dynamics cyclic loads are inevitable in most of these applications which has an adverse effect on the fatigue life of the critical parts. Ensuring close dimensional tolerances and coaxiality during machining is highly desirable, as it affects the rotary characteristics in many applications. Thus, control of coaxiality error plays a vital role in rotating shafts and high precision machine tools. However, use of high precision machining would drastically increase the cost of manufacturing. Thus, a cost-effective machining process that could potentially reduce the coaxiality error is of high industrial importance. The present research efforts made an attempt to achieve minimum coaxiality error on cylindrical machined parts by optimizing parameters (cutting speed, feed rate, depth of cut and cutting tool nose radius). Experiments are planned, viz. central composite design matrix and statistical analysis determine the influence of machine parameters on coaxiality error of high-strength Al 7075 alloy by applying response surface methodology. Feed rate and depth of cut factors showed significant effect on coaxiality error. All machining parameters showed a non-linear effect on coaxiality error, which defines the strong interaction factor effects. The empirical equations derived were used to minimize coaxiality error by determining a set of machining parameters, viz. applying Big-Bang and Big Crunch and Rao (Rao-1, Rao-2 and Rao-3) algorithms. Rao algorithms outperform the Big-Bang and Big Crunch algorithm both in computation effort and solution accuracy. The results of Rao algorithms are experimentally verified, which resulted in reduced coaxiality error equal to 1.013 µm and resulted in 72.6% improvement compared to CCD experiments.

Modeling and Optimization of the Bubble Detachment Diameter for a Pool Boiling System

AbstractPrediction of boiling heat transfer for pool boiling systems is crucial from the viewpoint of safe operation as well as in terms of logical use of energy. Here, five pool boiling processes for calculating the bubble detachment diameters are described. The effects of liquid density and vapor density on the bubble detachment diameter of these pool boiling systems, namely, ethanol, methanol, water, Na2SO4‐water, and NaCl‐water, are determined by applying response surface methodology. According to P‐values and analysis of variance, there is a good agreement between the obtained regression models for the five pool boiling processes and experimental data for estimation of the bubble detachment diameters.

Deep oxidative desulfurization via rGO-immobilized tin oxide nanocatalyst: Experimental and theoretical perspectives

In this contribution, reduced grapheme oxides (rGO) with immobilized tin oxide (SnO2) nanocatalysts were synthesized via the Incipient Wetness Impregnation (IWI) method. To characterize the SnO2/rGO composites, several analyses including the; XRD, Raman, FTIR, ICP-OES, BET-BJH, XPS, TEM, and TPD were utilized. Then the effects of parameters including reaction time, total metal loading, and the initial sulfur concentration of model fuel in the dibenzothiophene (DBT) oxidation desulfurization process were evaluated. After determining the optimal conditions for the aforementioned parameters, the influences of 3 effective factors of the molar ratio of oxidant/substrate (O/S), the molar ratio of catalyst/substrate (Cat/S), and reaction temperature were investigated by applying response surface methodology (RSM). Results revealed that through employing the SnO2 (15)/rGO catalyst, the DBT conversion of 96% was obtained at the following optimum conditions: time = 180 min, initial sulfur concentration = 500 ppm, molar ratio of O/S = 30, temperature = 60 °C and molar ratio of Cat/S = 0.06. Next, 1H NMR and FTIR techniques were performed for the final product assessment. Ultimately, to investigate the importance of the rGO upon the DBT oxidation, density functional theory (DFT) calculations were utilized. Interaction energy, Reactivity parameters, ESP, and RDG results revealed the influence of the rGO in the adsorption of the DBT through the π–π interactions.

Investigation on Cell Disruption Techniques and Supercritical Carbon Dioxide Extraction of Mortierella alpina Lipid.

Mortierella alpina, an oleaginous fungus, has been shown to be a potential source for arachidonic acid (ARA) production. The recovery of intracellular lipids from M. alpina is an important step for the downstream bioprocessing, and green extraction techniques with a focus on being efficient and eco-friendly have drawn much attention. In this study, different cell disruption techniques (mechanical: high-speed homogenization 10,000 rpm, ultrasonication 20 kHz, high-pressure process (HPP) 200–600 MPa; non- mechanical: acid treatment HCl) were investigated for lipid recovery from M. alpina, and process parameters (A. temperature, B. pressure, C. cosolvent ratio) of supercritical carbon dioxide (SC-CO2) lipid extraction were studied by applying response surface methodology (RSM). Compared with Soxhlet extraction as a control group (100%), high-speed homogenization has the highest lipid recovery (115.40%) among mechanical disruption techniques. Besides, there was no significant difference between high-speed homogenization and 1 M HCl treatment (115.55%) in lipid recovery. However, lipid recovery decreased to 107.36% as the concentration of acid was increased to 3 M, and acid treatment showed a negative effect on the ARA ratio. In HPP treatment, the highest lipid recovery (104.81%) was obtained at 400 MPa, 1 time of treatment and water medium. In the response surface model of SC-CO2 extraction, results showed the major influence of the process parameters to lipid recovery was pressure, and there are interaction effects of AC (temperature and cosolvent ratio) and BC (pressure and cosolvent ratio). Lipid recovery of SC-CO2 extraction reached 92.86% at 201 bar, 58.9 °C and cosolvent ratio 1:15. The microbial lipid recovery process of this study could be used as a reference and an eco-friendly alternative for the future downstream bioprocessing of ARA production by M. alpina.

Optimizing PET Glycolysis with an Oyster Shell-Derived Catalyst Using Response Surface Methodology.

Polyethylene terephthalate (PET) waste was depolymerized into bis(2-hydroxyethyl) terephthalate (BHET) through glycolysis with the aid of oyster shell-derived catalysts. The equilibrium yield of BHET was as high as 68.6% under the reaction conditions of mass ratios (EG to PET = 5, catalyst to PET = 0.01) at 195 °C for 1 h. Although biomass-derived Ca-based catalysts were used for PET glycolysis to obtain BHET monomers, no statistical analysis was performed to optimize the reaction conditions. Thus, in this study, we applied response surface methodology (RSM) based on three-factor Box–Behnken design (BBD) to investigate the optimal conditions for glycolysis by analyzing the independent and interactive effects of the factors, respectively. Three independent factors of interest include reaction time, temperature, and mass ratio of catalyst to PET under a fixed amount of ethylene glycol (mass ratio of EG to PET = 5) due to the saturation of the yield above the mass ratio. The quadratic regression equation was calculated for predicting the yield of BHET, which was in good agreement with the experimental data (R2 = 0.989). The contour and response surface plots showed the interaction effect between three variables and the BHET yield with the maximum average yield of monomer (64.98%) under reaction conditions of 1 wt% of mass ratio (catalyst to PET), 195 °C, and 45 min. Both the experimental results and the analyses of the response surfaces revealed that the interaction effects of reaction temperature vs. time and temperature vs. mass ratio of the catalyst to the PET were more prominent in comparison to reaction time vs. mass ratio of the catalyst to the PET.

Rapid biodegradation of diazinon using a novel strain of Candida pseudolambica

Diazinon has been widely applied in the agricultural sector as an organophosphorus insecticide because of its toxicity, while it is a serious threat to the biodiversity of the environment. A yeast strain being capable of biodegrading diazinon was isolated from pesticide-contaminated agricultural soil. Analysis of sequences spanning the Intergenic Spacer (ITS) region showed that the isolated strain was Candida pseudolambica. The ability of this strain for diazinon biodegradation was evaluated, and the condition of the aqueous solution was optimized applying response surface methodology (RSM) and validated by the artificial neural network (ANN). At the optimum condition, in a mineral salt medium (MSM) containing a high concentration of diazinon (775 mg/l) and 2.25 g/l glucose as a co-substrate with an inoculum size of 8% and incubated at 30 °C, the isolated strain of C. pseudolambica demonstrated 69.6% removal of diazinon in a short period of time (24 h). Substantial biodegradation efficiency (34%) was also achieved after 24 h incubation of the isolate in a medium that 500 mg/l of diazinon was utilized as the only carbon source. The optimum ANN model obtained with 5 neurons in the hidden layer resulted in R 2 > 0.98, and for the RSM, R 2 was 0.993. Results indicated the remarkable ability of the isolated strain for rapid degradation of high concentrations of diazinon, which could be promising for large-scale bioremediation applications. • Potential yeast strain in diazinon degradation was isolated from contaminated soil. • Rapid degradation of high diazinon concentration was achieved within 24 h. • Influential parameters on diazinon biodegradation were studied using RSM method. • ANN model greatly confirmed the RSM method application.

Impact prediction model of acetone at various ignition advance by artificial neural network and response surface methodology techniques for spark ignition engine

In this study, it was aimed to predict and optimize the effects of acetone/gasoline mixtures on spark ignition engine responses at different engine speeds and ignition advance values with artificial neural network and response surface methodology. The regression results obtained from response surface methodology show that absolute variance ratio values for all answers are greater than 0.96. Correlation coefficient values obtained from artificial neural network were obtained higher than 0.91. Mean absolute percentage error values were between 0.8859% and 9.01427% for artificial neural network, while it was between 1.146% and 8.957% for response surface methodology. Optimization study with response surface methodology revealed that the optimum results are 1700 rpm engine speed, 2% acetone ratio and 11° before top dead center ignition advance with a combined desirability factor of 0.76523%. Additionally, in accordance with the confirmation analysis among the optimal outcomes and the estimation outcomes, it was stated that there is a great harmony with a maximum error percentage of 7.662%. As a result, it is concluded that the applied response surface methodology and artificial neural network models can perfectly provide the impact of acetone percentage on spark ignition engine responses at different engine speeds and ignition advance values.

Phenolics from potato peel and its extraction intensification using response surface methodology and genetic algorithm approach

Potato peels are zero value waste generated during potato processing. They are a concentrated source of phytochemicals. The extraction of phenolics from this waste may add valuable products for the growing food industry due to their antioxidant and antimicrobial properties. In this study, phenolics were extracted from potato peel by using ultrasound assisted extraction process with combination of sonication time (5–25 min), ethanol concentration (0–100%) and extraction temperature (25–65°C) as independent variables using central composite design (CCD). The process parameters were optimized by first applying response surface methodology (RSM) followed by genetic algorithm (GA) approach. The extraction parameters were optimized for maximum total phenol content (TPC). Using genetic algorithm approach the optimized conditions for maximum recovery of total phenols (621.27 mg/100g dwb) from potato peel are 22.032 min sonication time at 61.818°C in 99.99% ethanol. Ultrasound assisted extraction was highly efficient compared to conventional solvent extraction in increasing the extraction yield by 2.84 fold. Optimized condition along with the predicted model provides a bright opportunity for food industry with great health advantages.

Optimization of Cultural Conditions for Keratinase Production by <i>Curvularia lunata</i> (JK17) using Response Surface Methodology

This study presents optimum cultural conditions for the maximum keratinase production in SSF applying response surface methodology. The maximum enzyme activity of 123 U/mL for Curvularia lunata was observed at cultural condition 12.72 days incubation, temp. 35oC, 5.6 g feather, 4.9 g carbon, 5.9 g nitrogen. Three-dimensional response surface and contour plots were drawn to find the relationship between keratinase production and cultural conditions. These values optimum for keratinase production by Curvularia lunata were in good accord with the experimental result.

Insights into the synthesis optimization of Fe@SiO2 Core-Shell nanostructure as a highly efficient nano-heater for magnetic hyperthermia treatment

Maintaining the intact iron core, protecting the extra iron ion release, and generating biologically sufficient heat, are the critical aspects for magnetic hyperthermia treatment (MHT). Thus, the composition of silica-coated nanoscale zero-valent iron (nZVI) was optimized by applying response surface methodology (RSM) and changing the molar ratio of tetraethyl orthosilicate (TEOS) and iron(II) sulfate (FeSO4·7H2O) as the silica and iron precursors, respectively. The TEOS/FeSO4·7H2O molar ratio of 1.67 results in the maximized saturation magnetization (99.3 emu/g) and the crystalline phase of pure iron. In comparison with the previously reported studies, the synthesized core–shell nanostructures demonstrate superior heat production features. As silica coating protects the inner core from oxidation and results in more effective heat-generating seeds, nanostructures with a higher amount of silica precursors, i.e., 10.3 mm, demonstrate an efficient specific absorption rate (SAR). Moreover, the medium and higher TEOS amounts represent acceptable cytocompatibility up to 125 μg/mL and 250 μg/mL, respectively. In vitro hyperthermia evaluation depicts the cancer cell viability reduction indicating the hyperthermia-induced apoptosis. Based on the data mentioned above, we could introduce a potential successful nanoparticle for magnetic hyperthermia treatment.

Effective Detoxification of Aflatoxin B1 and Ochratoxin A Using Magnetic Graphene Oxide Nanocomposite: Isotherm and Kinetic Study

One of the approaches for reducing exposure to mycotoxins is to lessen their bioavailability by applying nanocomposite adsorbents. Magnetic graphene oxide (MGO) is a new class of nanostructured multifunctional nanocomposite materials, which play a vital role as an adsorbent. The primary aim of this study is to apply response surface methodology (RSM) to optimize the influence of pH within the range of 3 to 7, time (3–7 h), and temperature (30–50 °C), on the simultaneous detoxification of aflatoxin B1 (AFB1) and ochratoxin A (OTA) by using MGO. The optimal condition was obtained at pH 5, 5 h, and 40 °C. Further investigation of the adsorption evaluation was carried out by studying different parameters, such as the influence of contact time, initial mycotoxins concentration, and temperature. According to the experimental data, it can be concluded that the pseudo-second-order kinetic model and the Freundlich isotherm fitted well. The capability of adsorption for the Freundlich model was calculated as 153 and 95 ng/g for AFB1 and OTA, respectively. The thermodynamic study showed that the sorption studies act spontaneously as an exothermic process. These findings suggest that the application of MGO as a nanocomposite is of great significance for the detoxification of mycotoxins.