Box-Bhenken Design Research Articles

Proniosomes Nanoparticle for the Treatment of Peripheral Arterial Disease.

The common symptom of systemic atherosclerosis is peripheral arterial disease (PAD), which occurs when the artery lumen in the lower extremities gradually becomes blocked by atherosclerotic plaque. The most frequent symptom of lower extremity PAD, called "vascular claudication," which is pain experienced when walking. Partial or total blockage of the peripheral arteries in the upper and lower limbs is called PAD. The danger of death from concurrent coronary artery and cerebrovascular atherosclerosis outweighs the risk of amputation. However, niosomes have issues with fusion, aggregation, leakage, vesicle sedimentation, and difficulty in sterilizing. A more recent strategy known as pro-vesicular carriers was used to solve these issues. The formulations in Proniosomes are dry and anhydrous, protected with a non-ionic surfactant that serves as a carrier when combined with water. Formulation prepared by organic solvent, surfactant, cholesterol, other components and hydration medium. Coacervation Phase separation Technique used for proniosome Nanoparticle. Box Bhenken Design is used for optimization batches. In this context, we shall discuss the development of Proniosome for the treatment of peripheral arterial diseases. From here, we know that proniosome nanoparticles is pro vesicular system good characteristics and effectiveness for treating peripheral arterial diseases. Proniosomes may be created using various techniques, which may impact how they develop along with the drug's characteristics. They increase the drug's stability while being delivered while being entrapped. They don't need particular conditions for handling, protection, storage, or industrial manufacturing.

Bioremediation of Pymetrozine Using Pleurotus Eryngii (King Oyster Mushroom)

The biodegradation of pymetrozine pesticide was investigated with Pleurotus eryngii white rot fungus (WRF). The biomass was characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electrode microscopy (SEM) to verify surface functionality and morphology. FTIR results revealed fungal biomass is rich with multiple functional groups while SEM analysis showed that the surface of fungal biomass is irregular, porous, rough and heterogeneous. Bioremediation of pymetrozine with Pleurotus eryngii was monitored using ultraviolet-visible spectroscopy. The Box Bhenken Design optimization showed that Pleurotus eryngii degrades 93.3% of 0.20 mM pymetrozine at pH 5. Gas chromatography–mass spectrometry (GC-MS) was carried out to identify major metabolites formed during biodegradation of pymetrozine. Based on these results, pymetrozine was transformed to nicotinaldehyde and 4-amino-6-methyl-4,5-dihydro-2H- [1,2,4] triazine-3-one (AMDT).

Development, optimization and in vitro-in vivo evaluation of solid lipid microparticles for improved pharmacokinetic profile of bisoprolol

The current research aimed at designing and optimizing controlled release solid lipid microparticles (SLMs) of Bisoprolol (BPL) from biocompatible waxes by using Box-Bhenken design (BBD) for improving the drug pharmacokinetics, enhancing compliance in hypertensive patients as well as eliminating inefficiencies of traditional methods of drug delivery. Seventeen formulations (F1 to F17) of controlled release BPL loaded SLMs were made by melt emulsification technique where Carnauba wax (CW) and Ceresin wax (CSW) were used as carriers and Tween 80 was used as stabilizer. The SLMs were characterized using fourier transforms infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Results revealed that micromeritics properties of all SLMs were satisfactory and showed good percentage yield (PY) and entrapment efficiency (EE). The minimum EE was observed by formulation-1 (F1) as 21.66% whereas F3 has showed maximum EE as 88%. Results of in vitro release study revealed that all formulations showed a well-controlled release in simulated intestinal medium at pH 7.4. The formulation F3 with high wax concentration revealed best extended release characteristics (29%) in 12 h. The pharmacokinetics studies of SLMs demonstrated an expressively lower Cmax (maximum plasma concentration) of BPL (53.61 ± 2:52) with a satisfactorily higher time to achieve maximum plasma concentration (Tmax) of 10.24 h as compared to Cmax (79.63 ± 5.75) and Tmax (2.45 ± 3.83) of BPL released from commercial brands. Moreover the attainment of greater bioavailability of BPL was most probably due to the increase in half-life (20.44 ± 2.82), mean residence time (24.81 ± 4.22) and area under the plasma concentration level curve (AUC0–24) of 9688.6 ± 4.18 for BPL released from SLMs. Convincingly, the inventive technique could not only sustain the drug release in the in vitro and in vivo environment but also maintain the plasma drug concentration level constant for a longer time without elevating Cmax.

Development of Statistically Optimized Chemically Cross-Linked Hydrogel for the Sustained-Release Delivery of Favipiravir.

Nowadays, the use of statistical approaches, i.e., Box–Bhenken designs, are becoming very effective for developing and optimizing pharmaceutical drug formulations. In the current work, a Box–Bhenken design was employed using Design Expert version 11 to develop, evaluate, and optimize a hydrogel-based formulation for sustained release of an antiviral drug, i.e., favipiravir. The hydrogels were prepared using the free radical polymerization technique. β-Cyclodextrin (β-CD), N,N′-methylenebisacrylamide (MBA), acrylic acid (AA), and potassium per sulfate (KPS) were used as oligomer, crosslinker, monomer, and initiator, respectively. Three variables, including β-CD (X1), MBA (X2), and AA (X3) were used at various concentrations for the preparation of hydrogels, followed by evaluation of a sol–gel fraction, swelling, porosity, chemical compatibilities, in vitro drug release, and entrapment efficiency. The results of the studies revealed that the degree of swelling was pH dependent, the best swelling being at pH 7.2 (1976%). On the other hand, for the low sol fraction of 0.2%, the reasonable porosity made the hydrogel capable of loading 99% favipiravir, despite its hydrophobic nature. The maximum entrapment efficiency (99%) was observed in optimized hydrogel formulation (F15). Similarly, in vitro drug release studies showed that the prepared hydrogels exhibited a good, sustained release effect till the 24th hour. The kinetic modelling of drug release data revealed that the Korsmeyer–Peppas model was best fit model, describing a diffusion type of drug release from the prepared hydrogels. Conclusively, the outcomes predict that the hydrogel-based system could be a good choice for developing a sustained-release, once-daily dosage form of favipiravir for improved patient compliance.

First Report on the Bioremediation of Textile Industrial Effluents by Piptoporus Betulinus IEBL-3 by Using Response Surface Methodology

The current study was performed to optimize three different industrial textile effluent biodegradation potentials of a brown rot fungus, Piptoporus betulinus IEBL-3, to reduce environmental pollution. The Response Surface Methodology under the Box Bhenken Design was used for the optimization steps. Three ligninolytic enzymes named lignin peroxidase, manganese peroxidase and laccase were also studied during the biodegradation process. The biodegradation rate of the 3 industrial effluents varied between 67 and 76% at the initially optimized conditions. There was a 10%, 7% and 9% increase in the biodegradation of Mujahid textile (MT), Five Star textile (FST) and Sitara textile (ST) effluent, respectively, after the addition of various additional carbon and nitrogen sources in different ratios. The biological treatment decreases the Biological Oxygen Demand and Chemical Oxygen Demand values of the effluents well below the WHO-recommended values for the industrial effluents. The HPLC monitoring of the effluent’s biodegradation showed the appearance of new peaks, some of which may correspond to secondary amines. Study of ligninolytic enzymes during the biodegradation process confirmed their role in the biodegradation process, with lignin peroxidase having highest activity among the others. These findings suggest that P. betulinus is a potential fungus for the biodegradation of the dyes and effluents and can be a suitable candidate for this process.

Formulation, Optimization, In Vitro and In Vivo Evaluation of Saxagliptin-Loaded Lipospheres for an Improved Pharmacokinetic Behavior

The development and optimization of controlled release lipospheres (LS) from safe biocompatible behenic acid (BA) was performed for not only enhancing patient's compliance against highly prevailed chronic diabetes but also to vanquish the insufficiencies of traditional methods of drug delivery. The Box-Bhenken design (BBD) was utilized to statistically investigate the impact of formulation variables on percentage yield (Y1), entrapment efficiency (Y2), and SG-release (Y3) from saxagliptin- (SG-) loaded LS, and the chosen optimized LS were subjected to a comparative in vivo pharmacokinetic analysis against commercially available SG brand. The compatibility analysis performed by DSC and FTIR established a complete lack of interaction of formulation components with SG, while p-XRD suggested a mild transformation of crystalline drug to its amorphous form during encapsulation process. The spherical, free flowing smooth surface LS having zeta potential of -32 mV and size range of 11-20 μm were conveniently formulated. The obtained data for Y1 (30-80%), Y2 (30-70%), and Y3 (40-90%) showed a best fit with quadratic model. The pharmacokinetics analysis of LS showed a significantly decreased Cmax of SG (75.63 ± 3.85) with a sufficiently elevated Tmax (10.53 h) as compared to commercial brand of SG (99.66 ± 2.97 ng/mL and 3.55 ± 2.18 h). The achievement of greater bioavailability of SG was most probably attributed to higher level of half-life, mean residence time (MRT), and AUC0-24 for SG released from LS. Conclusively, the novel approach of SG-loaded LS had successfully sustained the plasma SG level for a prolonged time without increasing Cmax which would ultimately bring an effective management of chronic diabetes.

Valorization of date juice by the production of lipopeptide biosurfactants by a Bacillus mojavensis BI2 strain: bioprocess optimization by response surface methodology and study of surface activities.

Lipopeptides biosurfactants (BioS)are natural surface-active compounds produced by a variety of microorganisms. They have great interest in environmental, biomedical and agro-industrial fields. However their large-scale application and production is limited by the cost of culture media and the low yield of production. Therefore, the improvement of the production yields and the development of efficient and cost-effective bioprocess became of a great interest. In this aim, we applied the response surface method to optimize an economic BioSproduction by a newly isolated strain Bacillus mojavensis BI2 on date Juice called "Luegmi" as unique carbon and nitrogen source. Using a Box-Bhenken design, we studied the effect of three independent variables on lipopeptide production; Leugmi concentration, Na2HPO4 and incubation time. The results of this study showed that Leugmi concentration at 25%, Na2HPO4 at 0.1% and incubation time of 24h were optimal conditions for BioS production, with a maximum Surface Tension (ST) decreasing capacity of 55% corresponding to 27 mN/m and an Oil Dispersing Activity (ODA) of 30 cm2 corresponding to a diameter of 6cm. Preliminary characterization of the BioSproduced on Luegmi by UV-Spectra and Thin Layer Chromatography showed its lipopeptide nature. Physic-chemical characterization of the produced lipopeptide on Leugmi showed its great surface activities and stabilities at different pH, temperature and salts concentration. The results of this study suggested that Leugmi, an agricultural byproducts can be used as a low-cost substrate to enhance the yield of lipopeptide BioS with great surface activities for potential environmental application.

Enhancement of Dissolution Rate and Bioavailability of Nifedipine by Chitosan Based Cocrystallization Technique

The objective of present study was to enhance solubility and dissolution behaviour of nifedipine by using cocrystallization method. A significant increase in solubility and dissolution rate of nifedipine has been demonstrated by solvent change method using chitosan. In this method, chitosan was precipitated on nifedipine crystals using sodium citrate as a salting out agent. An accurately weighed chitosan was dissolved in 1% acetic acid and drug was added in the chitosan solution. This resulting solution was added drop wise into 1% sodium citrate solution with continuous stirring. Sodium citrate precipitate polymer on drug crystals. FTIR, DSC, XRD, SEM, In-vitro dissolution studies, were studied for characterization of prepared cocrystals. Stability studies showed a good stability character of prepared cocrystals. Design Expert® software version 10.0 was used to develop polynomial models which were analysed to delineate the main effects for each CQA (critical quality attributes) through Box-Bhenken design expert. Pharmacokinetic study clearly showed the enhancement of dissolution rate of cocrystals. The above investigation concluded that the significant dose reduction is possible for nifedipine with cocrystal formulation which leads to improve patient compliance.

Development of Darunavir proliposome powder for oral delivery by using Box–Bhenken design

The aim of this study is to develop Darunavir (DRV) proliposome powder for oral delivery. Darunavir-loaded oral proliposome powder (OPP) was prepared by a solvent evaporation technique with varying independent variables at three different levels. Based on different levels, proliposome powder formulation was optimized by using Box–Behnken design. The formulations were analyzed for its size distribution, entrapment efficiency, and surface morphology. Optimized proliposome batch A was evaluated for physical parameter, morphological parameters, entrapment efficiency, followed by in vitro, ex vivo, and in vivo studies. Oral proliposome powder showed good micromeritic properties with angle of repose was less than 30°, Carr’s index and Hausner’s ratio were also less than 21 and 1.25, respectively. The mean size of the vesicles was in the range of 180–290 nm. The assay and entrapment efficiency of pro-liposome powder formulations were 79.00 ± 0.2 and 93.46 ± 0.2%, respectively. In vitro release of DRV proliposome powder was 78.17 ± 0.1% after 24 h which shows good release from the vesicle of proliposome. Ex vivo permeation study shows 58.11% enhancement which shows good permeation. The optimize batch A of proliposome powder indicated 50% enhancement in the relative bioavailability as compared to the DRV suspension. The results showed that proliposome powder containing DRV can efficiently deliver in to the blood stream. This drug delivery system has been designed as a novel platform for potential oral delivery of drugs having poor water solubility and high first-pass metabolism.

Ultrasound assisted extraction of cynaropicrin from Cynara cardunculus leaves: Optimization using the response surface methodology and the effect of pulse mode

In this study, conditions for ultrasound assisted extraction (UAE) of cynaropicrin from Cynara cardunculus leaves by assessing the effect of pulsed mode and different duty cycles were optimized. Pulse mode presented a reduction of 45 % on energy consumption/ g cynaropicrin extracted, comparatively to continuous mode, and a duty cycle of 25 % presented the highest kinetic rate between the duty cycles under study, with a lower number of pulse repetitions necessary to reach a steady state conditions. The extraction methodology was further optimized by response surface methodology (RSM), using a Box-Bhenken design with 3 factors (solid/liquid ratio, amplitude and temperature), and 3 levels for correlation of independent variables with the extraction yield (mg of cynaropicrin/g dry weight) and cynaropicrin concentration (mg cynaropicrin /g extract). Experimental results were fitted to a second order polynomial model, using multiple regression and analysis of variance to determine the fitness of the model. Optimal conditions were found for a solid/liquid ratio of 1/27, amplitude of 67 % and temperature of 44 °C, with a predicted value of 23.99 mg/g DW and 192.23 mg/g extract for extraction yield and cynaropicrin concentration, respectively. The predicted values fit the experimental ones, with a 95 % confidence level showing the accuracy of the model. The results obtained suggest the applicability of the UAE optimization methodologies described, for cynaropicrin extraction from Cynara cardunculus leaves, illustrating its potential application on biotechnological and agro food industries.

Evaluation and optimization on the formability of an AZ31B Mg alloy during warm incremental sheet forming assisted with oil bath heating

This paper introduces an innovative warm incremental sheet forming approach with global heating through an oil bath setup as a heat source to form Mg alloy sheets. An attempt was made to evaluate and optimize the formability of the proposed approach using the maximum forming angle as a measure of process viability. Then, a series of experiments were conducted according to a Box-Bhenken design, including response surface methodology and an analysis of variance. Next, the results indicated the innovative approach was able to form AZ31B Mg alloy sheets with great feasibility. The most influential factor affecting the formability was the forming temperature, followed by the step depth, sheet thickness and tool diameter. The reasons for those results were also explained. Finally, the experiments validated the predictive model by evaluating an optimal combination of considered parameters for improving the formability of the AZ31B Mg alloys.

Large‐volume sample stacking with polarity switching for analysis of azo dyes in water samples by capillary electrophoresis

ABSTRACTA simple, fast and efficient on-line pre-concentration method (large-volume sample stacking) by capillary electrophoresis was proposed for determination of azo dyes residues (allura red [AR], sunset yellow [SY] and tartrazine [TAR]) in water samples. Pre-concentration variables involved in the system were optimised using of a Box–Bhenken design. Under the optimal conditions: injection time 150.0 s, pre-concentration time 120.0 s and reverse potential −8.0 kV, the proposed methodology improved the analytical sensibility achieving limits of detection of 21.0–41.4 µg L−1 with enrichment factors of 82.1–210.8 fold. The large-volume sample stacking-capillary electrophoresis method was validated and applied to determine azo dyes residues in 20 water samples (bottled, spring and tap water). Two samples were positive for sunset yellow and tartrazine with a concentration of 25.3 and 30.2 µg L−1 and % RSD less than 10.0% in all cases.

Effect of laser surface texturing on wear resistance of nickel based superalloy

PurposeThis paper aims to investigate the effect of laser surface texturing (LST) on the wear behavior of C-263 nickel-based superalloy and to identify the optimum wear operating condition.Design/methodology/approachC-263 nickel-based superalloy was selected as substrate material and pico-second Nd-YAG laser was used to fabricate the waviness groove texture on their surface. Wear experiments were designed based on Box-Bhenken design with three factors of sliding velocity, sliding distance and applied load. Wear experiments were performed using pin on disc tribometer. Morphologies of textures and worn-out surfaces were evaluated by scanning electron microscopy and energy dispersive spectroscopy. Surface topographies and surface roughness of the textures were evaluated by weight light interferometry. The response surface methodology was adopted to identify the optimum wear operating condition and ANOVA to identify the significant factors.FindingsLST improves the wear resistance of C-263 nickel-based superalloy by appeoximately 82 per cent. Higher wear rate occurs at maximum values of all operating conditions, and applied load affects the coefficient of friction. Applied load significantly affects the wear rate of un-textured specimen. The interaction of sliding velocity and applied load also affects the wear rate of textured specimens. The optimum parameters to get minimum wear rate for un-textured specimens are 1.5 m/s sliding velocity, 725 m sliding distance and 31 N of applied load. For textured specimens, the optimum values are 1.5 m/s sliding distance, 500 m sliding distance and 40 N of the applied load.Originality/valueLiterature on laser texturing on nickel-based superalloy is very scarce. Specifically, the effect of laser texturing on wear behavior of the nickel-based superalloy C-263 alloy is not yet reported.

Modeling of the mechanical properties of directionally solidified Al-4.3% Cu alloy using response surface methodology

With increasing demand of high strength to low weight ratio materials, aluminum alloys are getting more commercial importance. Investment casting process following by directional solidification has the capability to produce cast parts with minimum or no grain boundary. These cast parts can perform even at elevated temperatures with improved mechanical properties, especially creep. Owing to these embedded capabilities, directional solidification process is preferred over conventional casting procedures for aluminum alloys. Properties of directionally solidified components highly depend on input parameters. This research aimed to develop the mathematical models for the prediction of ultimate tensile strength (UTS), percentage elongation, and hardness of directionally solidified Al-4.3% Cu alloy. A series of experiments were performed to investigate the effects of grain selector parameters including spiral thickness, spiral diameter, spiral pitch, and spiral rotations using Box-Bhenken design. For the adequacy and validity of mathematical models, analysis of variance (ANOVA) and confirmation experiments were performed, respectively. Spiral thickness was observed as most effective parameter affecting UTS, percentage elongation, and hardness followed by spiral pitch and spiral diameter. Microstructural analysis reveals that grain boundaries disappeared at low level spiral thickness and pitch and high level of spiral diameter and rotations. In comparison with base metal, percentage improvement in UTS, percentage elongation, and hardness ranging from 37.5~93.9%, 20.5~81.3%, and 37.6~85.3%, respectively, has been observed. Innovation in this research is the mathematical modeling of mechanical properties for Al-4.3% Cu alloy using directional solidification process.

Optimization of process parameters using graphene-based dielectric in electric discharge machining of AISI D2 steel

Hard to machine materials have growing demand in industrial sector especially in nuclear, automotive, and aerospace industries for sustainable production. These materials cannot be machined by typical machining methods or conventional methods, and for machining such materials, nonconventional machining method are usually used. Electric discharge machine is widely used for machining such materials and complex geometries. This research aims to optimize the process parameters while electric discharge machining of AISI D2 steel using nanofluids. The effects of four most influencing factors including pulse-off time, discharge current, pulse-on time, and conc. of nanoparticles have been investigated. Graphene nanoplatelets mixed with kerosene oil were used as a dielectric. Box-Bhenken design based on response surface methodology (RSM) was used for experimentation. Regression models for performance measures such as material removal rate, surface roughness, and white layer thickness have been developed using RSM. ANOVA has been carried out for identifying the most significant factors. Multi-objective optimization has been carried out in terms of desirability function by establishing a compromise between maximum material removal rate and minimum surface roughness and white layer. ANOVA results shows that conc. of nanoparticles is the most significant parameter affecting the performance measures followed by the discharge current. The confirmatory tests were run for verifying and validating the results, and improvements in the performance measures such as MRR, Ra, and WLT up to 21.93 mm3/min, 3.98 μm, and 19.13 μm, respectively, at an optimum have been observed. Multi-response optimization yielded compound desirability of 85.7% for the selected levels of process parameters for machining of AISI D2 steel.

Alkali pretreatment of cotton stalk for bioethanol

Cotton stalk biomass was treated with NaOH and NaOH-steam pretreatements to get maximum cellulose content. Three factors with three levels such as biomass concentration (5, 10 and 15%), NaOH concentration (1, 3 and 5%) and residence time (4, 6 and 8 h) was performed through Box-Bhenken Design of response surface methodology. The treatment was performed with and without heating at 121oC for 15min and 15psi in an autoclave. Among these two types of treatment, maximum yield of cellulose content 87.80% was observed with 5% w/v NaOH concentration, 10g substrate loading and 4h residence time. The substrate having high cellulose content under optimized pretreatment conditions were analysed through FTIR revealing efficiency of pretreatment. The proposed model for this study was found significant in terms of lower p<0.05 values and findings of this study could be utilized for further processes like saccharification and fermentation to bioethanol.
 Bangladesh J. Sci. Ind. Res.54(1), 73-82, 2019

Optimization of Zinc Ions Removal by Modified Phoenix Dactylifera L. Seeds Using Response Surface Methodology

The current study investigates the role of Phoenix Dactylifera L. (date palm) seeds as an effective biosorbent for removing Zn+2, a toxic heavy metal pollutant usually found in the waste streams of industries like fertilizer, mining and galvanizing etc. Date palm seeds were washed, dried, crushed in 170-300 um and modified by acidic treatment (0.1 MHNO3). The effect of most important parameters i.e., pH (3.5-6.1), initial zinc ion concentration (5-100mg/l), biosorbent dosage (0.1-1g) and contact time (0.5-60sec) have been studied via design expert software (version 8.0.6) of response surface methodology. The Box-Bhenken Design (BBD) was used in Response Surface Methodology (RSM) for designing the experiments and a number of 29 experiments were run. The model suggested by the design expert software was quadratic as it had maximum R2- value (0.9235) which indicated that the predicted values of quadratic model were best fitted to the experimental values. The significance of the factors was indicated by Analysis of Variance (ANOVA). The results showed that the metal uptake increased by increasing initial zinc concentration and decreasing in biosorbent dosage and pH while the contact time had negligible effect on the response surface. The parameters were numerically optimized and the optimum input parameters obtained were pH = 3.52, initial zinc ion concentration = 59.11ppm, biosorbent dosage = 0.1g and contact time = 60min with a metal uptake of 26.84mg/g. Therefore, (Phoenix Dactylifera L.) seeds substantially removed zinc ions under optimum conditions.

Investigating the effects of electric discharge machining parameters on material removal rate and surface roughness on AISI D2 steel using RSM-GRA integrated approach

The present research focuses on optimizing the process parameters of die-sinking electric discharge machining on tool steel. The basic objective of this research is to investigate the influence of two categorical factors including dielectric type and electrode polarity, and two numeric factors including discharge current, and Spark/Discharge Gap on material removal rate (MRR) and surface roughness (Ra) for machining of AISI D2 steel. Box-Bhenken design based on response surface methodology (RSM) was applied for experimental design. For estimation and evaluation, the effects of the process parameters on response variables, RSM has been integrated with grey relational analysis (GRA). Ranking of factors has been done with respect to the grey relational grade. (ANOVA) was further performed for determining the significance of grey relational grade. ANOVA results reveal that that polarity having 50% of percentage contribution was the most significant factor affecting the performance measures followed by the spark gap, discharge current, and dielectric type. The grey relational grades were further optimized through desirability function and the optimal condition for input parameters was obtained. The optimum levels were discharge current at 15 A, dielectric type of kerosene oil, spark gap at 6 mm, and polarity of positive has been determined. The confirmatory tests were run for verifying and validating the results and improvement in productivity (MRR) up to 17.23 mm3/min and quality (Ra) up to 3.86 μm at an optimum have been observed.

Optimisation of the size distribution of ball mill product by modelling grinding variables using DX8 software

ABSTRACT Proposed approaches for optimisation of size distribution of ball mill product are to minimise the product 80% passing size or to reach the desired product size while minimising the amount of −37 μm fraction to prevent overgrinding. Grinding experiments were conducted using a laboratory ball mill with copper sulphide ore. The d80 and the amount of −37 μm fraction in the product were defined as process responses to model the ball mill grinding based on Box-Bhenken design method using DX software. Ball size, grinding time and solid content of ball mill were selected as model variables. The results indicated that the optimum values of responses from model predictions were very close to experimental responses. This study demonstrates that RSM and Box-Bhenken design can be successfully used for the determination of grinding parameters to optimise the size distribution of product.

PRODUCCIÓN DE PROTEASAS A PARTIR DE Bacillus safensis EN FERMENTACIÓN SUMERGIDA USANDO METODOLOGÍA DE SUPERFICIES DE RESPUESTA

In present study, various cultural parameters for Bacillus safensis were optimized in submerged fermentation for alkaline protease production using response surface methodology. Nutritional components were screened through Placket-Burman design. The optimized cultural parameters were, 1% inoculum, initial medium pH 9.0, incubation temperature 30OC and fermentation time 72h. Among nutritional parameters, casein, KH2PO4 and peptone were found significant which were further optimized through Box-Bhenken Design with three levels. The experimental results showed that 4.0% casein, 0.05% KH2PO4 and 0.575% peptone yielded highest protease production. The proposed model was significant which clearly explained the response. The crude protease produced by Bacillus safensis showed optimum activity at pH 8.0 and at 40oC. Kinetics revealed that the Km and Vmax values of 1.027 mg/ml and 67.57 mg/ml/min using casein as substrate, respectively