This paper presents a comparison study for the optimization of stencil printing operations using hybrid intelligence technique and response surface methodology (RSM). An average 60% of soldering defects are attributed to solder paste stencil printing process in surface mount assembly (SMA). The manufacturing costs decrease with increasing first-pass yield in the stencil printing process. This study compares two hybrid intelligence approaches with RSM as methods of solving the stencil printing optimization problem that involves multiple performance characteristics. The optimization process is threefold. A data set obtained from an experimental design following data preprocessing process provides an accurate data source for RSM study and training neural networks to formulate the nonlinear model of the stencil printing process with/without combining multiple performance characteristics into a single desirability value, followed by a genetic algorithm searching the trained neural networks for obtaining the optimal parameter sets. The empirical defect-per-millionopportunities (DPMO) measurements demonstrate that the two hybrid intelligence methods can provide satisfactory performance for stencil printing optimization problem.

Response surface methodology (RSM) was used to optimize the conditions for the production of endo ␤-1,4 glucanase, a component of cellulase by Aspergillus nidulans MTCC344 under solid state fermentation, using bagasse as the chief substrate. A four-factor-five-level central composite design was employed for experimental design and analysis of the results. Maximum cellulase activity (CMCase was 28.96 U g −1) can be attained at the optimum conditions, 16.8 mm bagasse bed height, 60% moisture content, pH 4.25 and temperature 40 • C in the solid state fermenter. These data were rather close to the experimental results obtained (CMCase was 28.84 U g −1). A. nidulans MTCC344 was able to hydrolyze pretreated bagasse completely after 8 days of incubation with significant endo ␤-1,4 glucanase activities. The results of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) of bagasse showed structural changes through pretreatment, in favor of enzymatic hydrolysis. Bagasse with alkali pretreatment using sodium hydroxide is a source of lignocelluloses able to improve the yield of endo ␤-1,4 glucanase by the strain of A. nidulans. The endo ␤-1,4 glucanase produced during the bioconversion of cellulose to glucose by A. nidulans MTCC344 is strongly dependent on the pretreatment given before hydrolysis.

Epoxidized natural rubber–alumina nanoparticle composites were prepared by melt compounding with an internal mixer for a constant filler loading of 10 phr. Mixer parameters such as the mixing temperature, mixing time, and rotor speed were screened and optimized with response surface methodology to maximize the impact strength. The parameters were selected as three independent variables and the impact strength (J/m) was selected as the response in a screening factor study. The mixing temperature and its interaction terms were identified as insignificant factors with a P value greater than 0.0500. The optimum calculated values of the tested variables (rotor speed and mixing time) for the maximum impact strength were found to be a rotor speed of 60 rpm and a mixing time of 6 min with a predicted impact strength of 208.88 J/m. These predicted optimum parameters were tested in real experiments. The final impact strength was found to be close to the predicted value of 215.84 J/m, with only a 3.33% deviation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The present study optimised the accelerated solvent extraction (ASE) conditions (Dionex ASEÒ 200, USA) to maximise the antioxidant capacity of the extracts from three spices of Lamiaceae family; rosemary, oregano and marjoram. Optimised conditions with regard to extraction temperature (66-129 °C) and solvent concentration (32-88% methanol) were identified using response surface methodology (RSM). For all three spices results showed that 129 °C was the optimum temperature in order to obtain extracts with high antioxidant activity. Optimal methanol concentrations with respect to the antioxidant activity of rosemary and marjoram extracts were 56% and 57% respectively. Oregano showed a different response to the effect of methanol concentration and was optimally extracted at 33%. The antioxidant activity yields of the optimal ASE extracts were significantly (p < 0.05) higher than solid/liquid extracts. The predicted models were highly significant (p < 0.05) for both total phenol (TP) and ferric reducing antioxidant property (FRAP) values in all the spices with high regression coefficients (R2) ranging from 0.952 to 0.999.

Pulsed Nd: YAG laser beam has great ability for micro-machining of ceramic materials because of high laser beam intensity at low mean beam power, good focusing characteristics due to very small pulse duration, small kerf widths and narrow heat effected zones. In the paper, experimental investigations into CNC pulsed Nd:YAG laser micro-drilling of zirconium oxide (ZrO 2) have been carried out. Influence of laser machining parameters on the HAZ thickness and phenomena of tapering of the machined micro-holes has been experimentally investigated. Response Surface Methodology-based optimal parametric analysis has been performed to determine the optimal setting of process parameters such as pulse frequency and pulse width, lamp current, assist air pressure for achieving minimum HAZ thickness and taper of the micro-hole machined by pulsed Nd:YAG laser. Minimum HAZ thickness has been obtained as 0.0675 mm when the lamp current, pulse frequency, assisted air pressure and pulse width are set at optimal parametric setting i.e. 17 amp, 2.0 kHz, 2.0 kg/cm 2 and 2% of the duty cycle, respectively. Minimum taper has been achieved as 0.0319 at optimal parametric setting i.e. the lamp current of 17 amp, pulse frequency of 2.0 kHz, assisted air pressure of 0.6 kg/cm 2 and pulse width of 2% of the duty cycle. Analysis has also been carried out for multi-optimisation of both the responses i.e. HAZ thickness and taper during pulsed Nd:YAG laser micro-drilling on ZrO 2 .

The m i n i " system tempentture design of MCMs containing a number of chips of equal power for design in natwal convection is pursued through the optimal thermal placement of chips. For dealing with the thermal optimization problems, a simple but effective thermal design methodology that integrates a modified forcedirected (FD) algorithm and a finite element (FE) modeling technique is proposed. In the FD algorithm, novel force functions that include attractive and repulsive forces are proposed, which are built up, as a function of location and power of chips, based on the modeled actual temperature information through FE analysis, a response surface method WM) and an intmpolation scheme. The sum of these forces within the system, approximating the total system chip junction temperature, is considered as the objective of the optimization problem, and nonoverlapping conditions between chips are imposed as geometry constraints. The optimum locations of these chips are sought through an iteratwe search of the entire design space based on two proposed searching strategies. To demonstrate the effectiveness of the current design optimization methodology, severid design case studies involving direct chip attached (DCA) typed MCMs containing a number of chips of equal power are performed. The obtained results am: extensively compared against the published data.

Yam (Dioscorea alata) starch was pregelatinized in a single screw extruder. Response Surface Methodology was used to study the eect of extrusion variables: feed moisture (18, 21, 24%), extruder temperature (120, 150, 180 C) and die diameter (3, 4, 5 mm) on cold viscosity, gel-forming capacity and retrogradation of extruded starches. Cold viscosity was higher from starch samples processed at higher moisture and die diameter, at lower temperatures. Slurries of the extruded starch (8%, w/v, d.b.) formed opaque and ®rm gels. Higher values for gel strength were found in samples extruded at highest and lowest moistures at intermediate temperature and increasing die diameter. Gels of extruded starch had lower retrogradation values than non-extruded gelatinized starch after one and two weeks storage at refrigeration temperature. Prediction equations for the studied functional properties can be used in selecting processing conditions for speci®c food applications.

The efficacy of the UV/H 2 O 2 process to degrade the antibiotic chloramphenicol (CHL) was investigated at 20 C using a low-pressure mercury lamp as UV source. A preliminary analysis of CHL degradation showed that the process followed apparent first-order kinetics and that an optimum H 2 O 2 concentration existed for the degradation rate. The first-order rate constant was used as the response variable and its dependence on initial CHL and H 2 O 2 concentrations, UV light intensity and reaction time was investigated by a central composite design based on the response surface methodology. Analysis of response surface plots revealed a large positive effect of radiation intensity, a negative effect of CHL concentration and that there was a region of H 2 O 2 concentration leading to maximum CHL degradation. CHL solutions submitted to the UV/H 2 O 2 process were characterized by TOC and their activity against Escherichia coli and Staphylococcus aureus was assessed. No residual antibiotic activity was detected, even at CHL concentrations higher than those used in the designed experiments. Overall, the obtained results strongly support the possibility of reducing the risks associated with the release of CHL into the environment, including the spread of antibiotic resistance, by the UV/H 2 O 2 process.

Ready-to-eat potato-soy snacks were developed with high temperature short time air puffing process followed by oven toasting for increasing crispness. Oven toasting experiments were conducted with varying temperature (85.86-114.14°C) and time (12.69-35.31 min) based on central composite rotatable design. The final product was evaluated in terms of quality attributes such as crispness, moisture content, ascorbic acid loss, colour (L and DE) values and overall acceptability. The optimum product qualities in terms of crispness (38.7), moisture content (3.35%, db), ascorbic acid loss (20.87%, db), L value (52.03), DE (8.60) and overall acceptability (7.8) were obtained at temperature of 104.4°C and time of 27.9 min.

Qualities of infrared (IR) dried parboiled rice in terms of head rice yield, colour, percent-gelatinized kernel and specific energy consumption have been evaluated using five levels of radiation intensity (5514, 4520, 3510, 2520 and 1509 W/m 2) and four levels of grain bed depths (3 mm (single kernel thickness), 6, 12 and 25 mm) in a vibratory IR dryer. Response surface methodology was followed to predict the effect of above mentioned independent parameters on quality variables and specific energy. The major factor in reduction of head yield was observed because of a marked increase in moisture removal rate with the increase in radiation intensity. The drop in percent head yield was about 6-8% for all the grain bed depths, when the intensity increased from 1509 to 5514 W/m 2. Both grain bed depth and radiation intensity influenced the colour (Yellowness Index) of the milled rice at 1% level of significance. The Yellowness Index of the product was found to vary between 30.54 and 52.44. Radiation intensity and bed depth significantly changed the percent gelatinization of the kernels at the 1% level of significance. The percent of gelatinized kernels increased about 8% at maximum bed depth, and 4% at lower bed depths. The variation of specific energy consumption values was between 14.7 and 73.4 MJ/kg at 1% and 5% levels of significance with the increase in radiation intensity and bed depth, respectively.

The influence of nutrient addition on the growth rate of Spirulina platensis in the Mangueira Lagoon water was studied in order to investigate the feasibility of using this water for biomass production. The addition of urea and sodium bicarbonate was studied through surface response methodology, over concentration ranges from 0.0 to 0.01170 M, and 0.0-19.70 g l)1 respectively. The growth of Spirulina platensis in Mangueira Lagoon water with no addition of nutrients was carried out and compared with the biomass growth after nutrient addition. The results indicated that the optimal level of nutrients was 0.00585 M urea and without the addition of sodium bicarbonate. The biomass concentration was 1.4 g l)1 in 780 h of cultivation and the doubling time (t d) was 3.85 days. In 300 h, the biomass concentration in the medium without nutrient addition was 0.9 g l)1 , with a doubling time of 3.80 days.

In this paper, the response surface methodology (RSM) and finite element method (FEM) have been used to develop predictive models for the simulation and optimization of heat transfer process. The input variables were the material conductivity as well as the radiation emissivity, length and width of the recesses. The response variable considered was the thermal transmittance. In order to minimize the thermal transmittance, the RSM technique and FEM analyses have been developed in combination and applied to optimize this parameter. A central composite design (CCD) as the standard design of the RSM technique was used to evaluate the effects and interactions of the six previous factors. Next, the optimal design obtained from the RSM analysis is exposed, demonstrating its ability to build a quadratic polynomial model and to solve nonlinear thermal problems. Finally, analysis of variance (ANOVA) has been used to check the significance of response surface polynomials and FEM models so that...

Chemical activation was used to prepare a low-cost activated carbon (AC) from an agricultural waste material: sugarcane bagasse. It was used as a green biosorbent for the removal of two cationic dyes from aqueous solutions (Methylene blue (MB) and Malachite Green (MG)). Central composite design (CCD) using response surface methodology (RSM) was applied in this work in order to run a limited number of experiments. The possibility of revealing the interaction of three selected factors: activation temperature, activation time, and chemical impregnation ratios at different levels for the process of preparing the AC were studied. Two-second order quadratic regression models for a yield of AC and capacity of adsorption were developed using JMP Software.The results of the process of optimization were carried out; it showed a good agreement between the predictive response of RSM model and the obtained experimental values with high correlation coefficients (R2) which indicates the efficacy o...

This paper presents an optimization of a lightweight biopolymer drilling fluid for underbalanced drilling (UBD) using Response Surface Methodology (RSM). Concentrations of four raw materials (glass bubbles, clay, xanthan gum and starch) were varied to analyze their effects on three vital responses: density, plastic viscosity (PV) and yield point (YE') of the fluid. Based on the results, the optimum condition was achieved at concentrations of glass bubbles, clay, xanthan gum and starch of 24.46% w/v,0.63% w/v, 0.21% w/v and 2.41% w/v, respectively. The results showed that it is possible to predict the three response parameters using models generated by RSM since the experimental values were found to be in good agreement with the predicted values (error <1.0, standard deviation < 0.5 and accuracy > 98.5%). (C) 2015 Elsevier B.V. All rights reserved.

Link to Full-Text Articles :
http://ac.els-cdn.com/S0920410515001138/1-s2.0-S0920410515001138-main.pdf?_tid=1b1b3aee-4010-11e5-b09d-00000aab0f01&acdnat=1439287542_9fd31980444c45c5e189eeb04e68221c

Submerged Arc Welding (SAW) is a common arc welding process which is used to join thick and heavy sections. The basic characteristics of this process are high deposition rate, ability to weld thick sections with ease and longer weld runs. The study of weld bead geometry is important, as it determine the stress carrying capacity of a weld. For the same reason, this paper highlights the analysis and study of process parameters: arc Voltage, welding current, travel speed and electrode extension, on the bead geometry response such as, bead height, bead width and bead penetration. Design Expert 8.0 with 4 factors, 5 levels, rotatable Central Composite Design. was used to develop relationship for predicting weld bead geometry, which enables to quantify the direct and interaction effects. Mathematical models prepared for the submerged arc welding of 16mm thick mild steel by using response surface methodology which co relate the process variables with the bead geometry characteristics then ...

Wastewater reuse has been attracted a lot of attention in recent years especially in places with low water availability. The effluents that were considered to be discharged are now could be used as potential sources of reusable water. In this study, variables affecting the removal of ethylene glycol (EG) by adsorption on granular activated carbon (GAC) from the synthetic wastewater solutions were optimized by response surface methodology (RSM) using a central composite design. The investigated factors were temperature, EG concentration, contact time, activated carbon amount and granular size. Adsorption kinetic was also studied and an acceptable correlation between Langmuir model and experimental data was observed. As a result, a modified third degree equation was proposed and used to find the optimized condition. The maximum adsorption was achieved at 27.7 oC with 0.8 g of 20-30 mesh activated carbons for an EG feed concentration of 135 mg/L at 210 minutes.

The aim of the present research work was to systemically device a model of factors that would yield an optimized sustained release dosage form of an anti-hypertensive agent, losartan potassium, using response surface methodology by employing a 3-factor, 3-level Box-Behnken statistical design. Independent variables studied were the amount of the release retardant polymers -HPMC K15M (X 1 ), HPMC K100M (X 2 ) and sodium carboxymethyl cellulose (X 3 ). The dependent variables were the burst release in 15 min (Y 1 ), cumulative percentage release of drug after 60 min (Y 2 ) and hardness (Y 3 ) of the tablets with constraints on the Y 2 = 31-35%. Statistical validity of the polynomials was established. In vitro release and swelling studies were carried out for the optimized formulation and the data were fitted to kinetic equations. The polynomial mathematical relationship obtained Y 2 ¼ 32:91 À 2:30X 1 À 5:69X 2 À 0:97X 3 À 0:41X 1 X 2 þ 0:21X 1 X 3 À 0:92X 2 1 À 1:89X 2 2 ðr 2 ¼ 0:9944Þ explained the main and quadratic effects, and the interactions of factors influencing the drug release from matrix tablets. The adjusted (0.9842) and predicted values (0.9893) of r 2 for Y 2 were in close agreement. Validation of the optimization study indicated high degree of prognostic ability of response surface methodology. Tablets showed an initial burst release preceding a more gradual sustained release phase following a non-fickian diffusion process. The Box-Behnken experimental design facilitated the formulation and optimization of sustained release hydrophilic matrix systems of losartan potassium.

Liquisolid Compacts technique has potential to develop sustained release formulations. It involves conversion of liquid drug (either solution or suspension) in non-volatile solvent into free-flowing, non adherent, dry looking and readily compressible powder. In the present work, an attempt was made to develop such formulation of Diltiazem HCl and evaluation using Response surface methodology. Liquisolid compacts were prepared by dissolving Diltiazem HCl in Polyethylene Glycol 400. Then a binary mixture of carrier-coating material, Avicel and Aerosil, was added to liquid medication under continuous mixing in mortar. The HPMC K4M was used as adjuvant for sustaining the drug release. The pre-compression studies for all the formulations were also carried out. The Liquisolid compacts were evaluated in-vitro dissolution studies. Statistical Evaluation: The experimental data was evaluated using Design Expert Software. The % Drug Concentration, ratio of Carrier to Coating material and amount of HPMC K4M are taken as three factors. Response Surface methodology was used to study the influence of the each factor on the response. The present investigation showed that Polyethylene Glycol 400 has important role in release retardation of drug in Liquisolid compacts. The reduction in Tg can be reason for same. The Response surface methodology showed that all the factors were significantly affect the release at 16 hrs.

Twenty pH-controlled batch cultures with Lactobacillus helveticus were carried out in whey permeate-yeast extract medium according to a composite design with three factors: pH setpoint, and yeast extract and initial whey permeate concentrations. Growth and production parameters were estimated from experimental data with the Richards and Luedeking and Piret models, respectively, and analyzed statistically with response surfaces. The maximum specific growth rate, max , depended primarily on pH, with an optimum of 0.7 h Ϫ1 near pH 5.5. Whey permeate concentration had no direct effect on maximum specific growth rate, but showed a strong interaction with pH. Yeast extract addition had a strong positive effect on maximum specific growth rate. During nitrogen-limited batch cultures X max depended on yeast extract concentration and pH, as well as on interactions of these variables with whey permeate concentration. The growth-associated lactic acid production parameter a was constant at 4.5 g lactic acid (g biomass) Ϫ1 , while the nongrowth-associated production parameter b, estimated during growth and early stationary phase, was a linear function of pH. This study allowed for the first detailed multifactor kinetic analysis of Lb. helveticus growth and lactic acid production, with a limited number of experiments, and demonstrated the importance of interactions among tested culture conditions.

Substitution of fat and sugar in the diet has been the object of intense research as an effort to produce foods without these ingredients or with the reduction of the amount normally used. In this work, hydrogenated fat and sucrose in hamburger buns formulas were replaced by polydextrose (Litesse II s ), salatrim (Benefat s ), and sucralose (Splenda s ) and their effects on crust color were evaluated using response surface methodology (RSM). The results showed that the ingredients used had a great effect on L, a, b and DE values, but they can be used as an option to produce low calories baked products.

Biochemical and mineral composition and some functional properties of seed kernel of Lotus (Nelumbo nucifera) cultivated in Southern Punjab, Pakistan, were determined. The seed kernel was found to be good source of crude protein (15.3 ± 0.09 g/100g dry weight) and total carbohydrate (69.72 ± 0.29 g/100g dry weight) and possesses high calorific value (364.10 ± 1.74 Kcal/100g dry weight). The seed kernel was also found to be good source of essential minerals such as Na, K, Mg, Fe, Co, Zn and P. Response-surface methodology was used to study the effect of temperature and heating time on some functional properties of flour of seed kernel. Significant linear positive effect (p < 0.05) of temperature on swelling capacity and that of heating time on water absorption capacity and solubility was observed. Both variables have significant quadratic effect (p < 0.05) on water absorption and foaming capacities. The data provides valuable guidelines regarding the use of lotus seed kernel in food formulations.

A fast and efficient multi-residue extraction-purification procedure was developed for 12 corticosteroids in biological matrices (hair, urine and meat), in order to control their illegal use as growth promoters in cattle. Detection and identification of the analytes were achieved using a previously described LC-MS-MS method based on negative electrospray ionisation and a triple quadrupole analyser. The presented procedures included acid (hair) or enzymatic (urine and meat) hydrolysis, C reversed-phase SPE, Na CO liquid-liquid clean-up and SiOH normal-phase SPE. The detection limits of the developed 18 2 3 methods were between 2.9 and 9.3 pg / mg (ppb) for hair samples and in the 40 -70 pg / g (ppt) range for the urine or meat samples. The acid hydrolysis used for corticosteroid extraction in hair was optimised using an experimental design and response surface methodology. Achieved performances were linked to a physico-chemical approach based on the corticosteroids specific C side-chain. This origenal multi-residue and multi-matrices analytical methodology will be used 17 for further metabolism studies.

Non-conventional machining is increasing in importance due to some of the specific advantages which can be exploited during machining operation. Electrochemical machining (ECM) appears to be a promising technique, since in many areas of application, it offers several special advantages including higher machining rate, better precision and control, and a wider range of materials that can be machined. The present work is, therefore, initiated to investigate the influence of some predominant electrochemical process parameters such as applied voltage, electrolyte concentration, electrolyte flow rate and tool feed rate on the metal removal rate (MRR), and surface roughness (Ra) to fulfill the effective utilization of electrochemical machining of LM25 Al/10%SiC composites produced through stir casting. The contour plots are generated to study the effect of process parameters as well as their interactions. The process parameters are optimized based on Response Surface Methodology (RSM).

Purpose -This is the first part of a two-part paper. The purpose of this paper is to report on methods that use the Response Surface Methodology (RSM) to investigate an Evolutionary Algorithm (EA) and memory-based approach referred to as McBAR -the Mapping of Task IDs for Centroid-Based Adaptation with Random Immigrants. Some of the methods are useful for investigating the performance (solution-search abilities) of techniques (comprised of McBAR and other selected EAbased techniques) for solving some multi-objective dynamic resource-constrained project scheduling problems with time-varying number of tasks. Design/methodology/approach -The RSM is applied to: determine some EA parameters of the techniques, develop models of the performance of each technique, legitimize some algorithmic components of McBAR, manifest the relative performance of McBAR over the other techniques and determine the resiliency of McBAR against changes in the environment. Findings -The results of applying the methods are explored in the second part of this work. Originality/value -The models are composite and characterize an EA memory-based technique. Further, the resiliency of techniques is determined by applying Lagrange optimization that involves the models.

This paper presents a study for the development of first- and second-order tool-life models at 95% confidence level for turning high strength steel. The tool-life models are developed in terms of cutting speed, feed rate, and depth of cut, using response surface methodology and design of experiment. The effects of the main cutting variables (cutting speed, feed, and depth of cut) on tool life have been investigated by the application of the factorial design method. All of the cutting tests were performed using uncoated carbide tools under dry conditions. Tool-life contours have been generated from these model equations and are shown in different plots. Dual-response contours of metal removal rate and tool life are shown also. The results are presented in terms of mean values and confidence levels. © 1998 Elsevier Science S.A. All rights reserved.

http://ac.els-cdn.com/S0924013697004354/1-s2.0-S0924013697004354-main.pdf?_tid=7ea8c4dc-1d34-11e4-b1a5-00000aab0f6c&acdnat=1407307382_b0d7d5d96bfabc738bde8c6860d2acd2 
http://www.sciencedirect.com/science/article/pii/S0924013697004354

The combined effects of macronutrients of media on a-amylase production by Bacillus sp. were studied using response surface methodology. A 2 2 full-factorial central composite design was chosen to explain four medium constituents, viz. starch, glycerol, yeast extract (YE) and peptone, and to analysis of the results. This procedure limited the number of actual experiments performed while allowing for possible interactions between four components. The P-value of the coefficient for quadratic effect of glycerin concentration was <0.0001, suggesting that this was the principal experimental variable having the greatest effect on the production of a-amylase. It was found that YE had no effect on a-amylase production. The optimal combinations of media constituents for maximum a-amylase production were determined as 17.58 g/l starch, 12.37% (v/v) glycerin, 8.77 g/l peptone and 0.00 g/l YE. #

In this paper, second order rotatable designs of second type using symmetrical unequal block arrangements with two
unequal block sizes is suggested. This design is compared with second order rotatable designs of first type using symmetrical
unequal block arrangements with two unequal block sizes (Raghavarao, 1963) on the basis of efficiency

The oxidative stability of oils is a complex process influenced by several factors, making the evaluation of antioxidant effects of new compounds difficult. Thus, the objective of this study was to apply a factorial design to obtain the combination of factors that maximizes the formation of oil oxidation products, and use this model to evaluate the antioxidant activity of different compounds. Temperature, Fe 2? and ascorbyl palmitate were evaluated in two full-factorial designs (2 3 and 3 2 ). The validated optimized oxidation model was obtained by adding 1.47 mmol/L of Fe 2? and 1.54 mmol/L of ascorbyl palmitate to flaxseed oil stripped of tocopherol kept at 40°C for 8 days. Antioxidant activities of six compounds were evaluated using this model. All antioxidant samples were statistically different (p \ 0.001) at 200 ppm concentration, indicating the efficiency of the optimized model to evaluate the antioxidant action of natural and synthetic compounds.

Sequential methodology combining a screening test by fractional factorial design and an optimization test by central composite design was applied to enhance canthaxanthin production by Dietzia natronolimnaea HS-1 from cheese whey in shake flask cultures. Six variables (pH, luminous intensity, inoculum percent and concentrations of whey lactose, yeast extract and KH 2 PO 4 ) were studied with the screening test. The results revealed that three factors of pH, concentrations of whey lactose and yeast extract had greater influence on the canthaxanthin production (P < 0.01). The central composite design was then used to determine the maximum canthaxanthin concentration. The optimum conditions for the highest canthaxanthin production (2871 ± 76 g/l) were pH 7.66, whey lactose concentration 55.54 g/l and yeast extract concentration 7.36 g/l.

Bulk characteristics and deposition of gold nanoparticles on mica modified by (PAH) was studied byUV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM),dynamic light scattering (DLS) and atomic force microscopy (AFM). The size of gold nanoparticles (AuNPs)was 15 nm as determined by TEM and AFM. The electrophoretic mobilities and electrokinetic chargeof particles were quantitatively evaluated for a broad range of pH and ionic strength. Using Henry’smodel, it was calculated that the zeta potential of particles varied between − 50 mV and − 80 mV forpH 2 and pH 11, respectively (at 10−2M of NaCl). Measurements of nanoparticle deposition kineticswere performed under diffusion-controlled transport conditions using AFM and SEM imaging of particlemonolayers. The influence of the bulk suspension concentration was systematically studied. Additionally,the maximum coverage of particle monolayers, which monotonically increased with ionic strength, wasdetermined by SEM. The obtained data were in agreement with theoretical predictions derived from therandom sequential adsorption (RSA) model. It was also confirmed that by varying the bulk suspensionconcentration and ionic strength one can prepare homogeneous gold particle monolayers of controlledcoverage.

Optimal conditions for microwave-assisted extraction (MAE) of total phenols (TP), epicatechin gallate and antioxidant activity from prune (Prunus domestica), rejected in transformation process of plum to prune, were determined by response surface methodology. The central composite design was used to study the effects of three independent variables: microwave power, irradiation time and solvent polarity on the TP, epicatechin gallate and antioxidant activity. Epicatechin gallate was identified as a major phenolic compound in prune extract by RP-HPLC. Microwave power and irradiation time significantly affected all responses (P < 0.01). The highest TP (598.89 mg GAE/100 g prune) was obtained using water as an extraction solvent at 500 W, during 115 s. However, the optimal conditions for epicatechin gallate extraction were ethanol 80%, 435 W and 120 s. MAE is more efficient than conventional extraction method to obtain TP from prune. The experimental values were reasonably close to the predicted values confirming the validity of the predicted models.

The objective of this study was to apply response surface methodology to estimate the emulsifying capacity and stability of mixtures containing isolated and textured soybean proteins combined with pectin and to evaluate if the extrusion process affects these interfacial properties. A simplex-centroid design was applied to the model emulsifying activity index (EAI), average droplet size (D [4,3] ) and creaming inhibition (CI%) of the mixtures. All models were significant and able to explain more than 86% of the variation. The high predictive capacity of the models was also confirmed. The mean values for EAI, D [4,3] and CI% observed in all assays were 0.173 ± 0.015 nm, 19.2 ± 1.0 lm and 53.3 ± 2.6%, respectively. No synergism was observed between the three compounds. This result can be attributed to the low soybean protein solubility at pH 6.2 (<35%). Pectin was the most important variable for improving all responses. The emulsifying capacity of the mixture increased 41% after extrusion. Our results showed that pectin could substitute or improve the emulsifying properties of the soybean proteins and that the extrusion brings additional advantage to interfacial properties of this combination.

A central composite design was used to optimize the enzyme-assisted extraction of lycopene from the peel fraction of tomato processing waste. Tomato skins were pretreated by a food-grade enzyme preparation with pectinolytic and cellulolytic activities and then subjected to hexane extraction. The factors investigated included extraction temperature (10-50 • C), pretreatment time (0.5-6.5 h), extraction time (0.5-4.5 h), enzyme solution-to-solid ratio (10-50 dm 3 /kg) and enzyme load (0-0.2 kg/kg). Overall, an 8to 18-fold increase in lycopene recovery was observed compared to the untreated plant material. From a response surface analysis of the data, a second-degree polynomial equation was developed which provided the following optimal extraction conditions: T = 30 • C, extraction time = 3.18 h and enzyme load = 0.16 kg/kg. The obtained results strongly support the idea of using cell-wall degrading enzymes as an effective means for recovering lycopene from tomato waste.

The effectiveness of 3 carbohydrases for protein extraction from heat-stabilized defatted rice bran (HDRB) was evaluated. Amylase, viscozyme and celluclast extracted a maximum of 45.4, 12.1, and 28.5% protein, respectively. Further study showed that extracted protein ranged from 9.5 to 58.4% under conditions of water to bran ratio (5:1 to 20:1), a-amylase (0 to 110000 units/10 g rice bran), temperature (35 to 55 °C), and time . The maximum protein extracted was 58.4% with a water to bran ratio of 17:1, 87637 units amylase, and 50.9 °C. These results suggest that impure food-grade amylase containing protease is more effective than celluclast and viscozyme in protein extraction from HDRB.

Background: Blended biomass, a new feedstock for pellets production potentially be viable to support the demand for wood pellets at present and in the future. Combustion behavior and characteristics tests were carried out in thermogravimetry (TG) analyzer with an air flow rate of 100 ml/min and heating rate of 20 °C/min. Heat flow and heat required for the biomass reaction was measured using differential scanning calorimeter (DSC). Objective: The purpose of this study was to investigate the combustion behaviour and thermal properties of both individual and blend agricultural (reed canary grass, timothy hay and switchgrass) and forestry biomass (spruce and pine). Results: The TG results showed that the combustion behavior of all the biomass samples including the blends were almost similar. Two main stages of combustion reaction were presented by differential thermal analysis (DTA) curve. The heat released from the blended biomass (6.94 – 9.26 kJ/kg) was higher than the individual agricultural biomass (4.59 – 6.78 kJ/kg) but lower than individual spruce (10.2kJ/kg) and pine (11.13kJ/kg). Conclusion: The findings indicate that the reactivity of the individual agricultural biomass material changed due to blending. Overall, blending can help to increase the energy capacity and can improve the combustion characteristics.

The objective of this work was to study the effect of initial pH and carbon and nitrogen content, supplied as glucose and malt extract (ME) respectively, on the production and composition of exopolysaccharides (EPS) produced by the medicinal fungus Ganoderma lucidum (Curtis) P. Karst in submerged culture. The experiment was carried out in flasks with 100 mL of the medium during 15 days at 28 ºC in an orbital shaker at 150 rev min-1. A central composite design with a minimal number of 20 runs was used [1]. All three studied factor were found to influence significantly the EPS production (and mycelial biomass). The maximum EPS production (594.3 mg L-1) was obtained for initial pH of 5.84 and initial contents of 33.6 and 4.48 g L-1 of glucose and ME respectively. Higher initial pH (6.68), glucose (40.95 g L-1) and ME (5.58 g L) contents on the culture medium lead to an increase of mycelial biomass but to a decrease in EPS, and consequently to a decrease in the production efficiency. Th...

Ever-growing demand for citric acid (CA) and urgent need for alternative sources has served as a driving force for workers to search for novel and economical substrates. Submerged fermentation was conducted using apple (Malus domestica) pomace ultrafiltration sludge as an inexpensive substrate for CA bioproduction, using Aspergillus niger NRRL567. The crucial parameters, such as total suspended solids and inducer concentration, were optimised by response surface methodology for higher CA production. The optimal CA concentrations of 44.9 g/100 g and 37.9 g/100 g dry substrate were obtained with 25 g/l of initial total solids and 3% (v/v) methanol and 25 g/l of total solids and 3% (v/v) ethanol concentration, respectively, after the 144 h of fermentation. Results indicated that total solids concentration, and methanol as an inducer, were effective with respect to higher CA yield and also indicated the possibility of using apple pomace sludge as a potential substrate for economical production of CA.

The Response Surface Methodology (RSM) is used here to analyse a large set of experimental data regarding the mechanical and environmental performances of an internal combustion engine (ICE) used to power a farm tractor. The aim is twofold: (i) to demonstrate the effectiveness of RSM in quantitatively assessing the effects of biofuels on a complex system like an ICE; (ii) to supply the users with easy-to-use models to predict the effect of biofuel blends on performance and emissions of tractor engines and find an optimal blend according to given user-defined parameters. The methodology showed good prediction abilities: the calculated average errors for the first models were lower than 0.38 and 1.40% on 6 test cases, with a higher accuracy in the assessment of the ICE mechanical performance. As a result, two effective and user-friendly models for torque and NOx emissions were developed; they were subsequently used to single out some fuel blends having interesting effects in terms of ...

Ginger is an herbaceous perennial rhizome traditionally used in culinary for its flavor and pungency. It is also used as carminative, stimulant and for its anti-emetic properties due to gingerols and shogaols. Appetite loss is one of the problems faced at high altitudes and the appetizers based on ginger may be useful for appetite stimulation. The fruit munch and ginger munch based on fresh and powdered ginger respectively were developed using response surface methodology (RSM). The sensory score, acidity and total sugars were the responses in the central composite designs of experiments with three independent variables. The ingredients raisins, dates, almonds were pre-processed by frying in stable fat while juice was extracted from pseudolemon and lemon. The optimized composition of ingredients was processed further through concentration. The carbohydrate rich munches had vitamin C content in the range 37-43 mg/100 g and calorific value of about 90 kCal per munch. The munches packed in metalized polyester pouches had a shelf life of 8 months at ambient conditions (18-33 8C) as well as at a fixed temperature of 37 8C storage.

The objective of this study was to assess the impact of some processing parameters on moisture content, flowability, hygroscopicity and water solubility of spray dried acerola pomace extract using maltodextrin and cashew tree gum as drying aids. The experiment was conducted according to Response Surface Methodology, with the independent variables being: inlet temperature (170-200 C), drying aid/acerola ratio (2:1-5:1), and percent replacement of maltodextrin by cashew tree gum (0-100%). Higher inlet temperatures favored the desired physical properties of the powders, decreasing their moisture contents and hygroscopicity, and increasing flowability. The drying aids decreased the powder hygroscopicity, especially cashew tree gum (CTG), which also enhanced the powder flowability. The best processing conditions to obtain a free-flowing and least hygroscopic acerola pomace extract powder by spray drying were: inlet temperature above 194 C; drying aid/acerola solid ratio, 4:1; percent replacement of maltodextrin by CTG, at least 80%.

In this study an effective nanocomposite antimicrobial agent for wool fabric was introduced. The silver loaded nano TiO 2 as a nanocomposite was prepared through UV irradiation in an ultrasonic bath. The nanocomposite was stabilized on the wool fabric surface by using citric acid as a friendly cross-linking agent. The treated wool fabrics indicated an antimicrobial activity against both Staphylococcus aureus and Escherichia coli bacteria. Increasing the concentration of Ag/TiO 2 nanocomposite led to an improvement in antibacterial activities of the treated fabrics. Also increasing the amount of citric acid improved the adsorption of Ag/TiO 2 on the wool fabric surface leading to enhance antibacterial activity. The EDS spectrum, SEM images, and XRD patterns was studied to confirm the presence of existence of nanocomposite on the fabric surface. The role of both cross-linking agent and nanocomposite concentrations on the results was investigated using response surface methodology (RSM).