Optimization of process parameters for acrylonitrile removal by a low-cost adsorbent using Box-Behnken design

In the present work, acrylonitrile removal from wastewater was investigated using an agri-based adsorbent-sugarcane bagasse fly ash (BFA). The effect of such parameters as adsorbent dose (w), temperature (T) and time of contact (t) on the sorption of acrylonitrile by BFA was investigated using response surface methodology (RSM) based on Box-Behnken surface statistical design at an initial acrylonitrile concentration, C(0)=100mg/l as a fixed input parameter. The results of RSM indicate that the proposed models predict the responses adequately within the limits of input parameters being used. The isotherm shows a two-step adsorption, well represented by a two-step Langmuir isotherm equation. Thermodynamic parameters indicate the sorption process to be spontaneous and exothermic.     

Optimization and characterization of gastroretentive floating drug delivery system using Box-Behnken design

Context: One among many strategies to prolong gastric residence time and improve local effect of the metronidazole in stomach to eradicate Helicobacter pylori in the treatment of peptic ulcer was floating drug delivery system particularly effervescent gastroretentive tablets.

Objective: The objective of this study was to prepare and evaluate, effervescent floating drug delivery system of a model drug, metronidazole.

Methods: Effervescent floating drug delivery tablets were prepared by wet granulation method. A three-factor, three levels Box-Behnken design was adopted for the optimization. The selected independent variables were amount of hydroxypropyl methylcellulose K 15M (X₁), sodium carboxy methylcellulose (X₂) and NaHCO₃ (X₃). The dependent variables were floating lag time (Y_FLT), cumulative percentage of metronidazole released at 6th h (Y₆) and cumulative percentage of metronidazole released at 12th h (Y₁₂). Physical properties, drug content, in vitro floating lag time, total floating time and drug release behavior were assessed.

Results: Y_FLT range was found to be from 1.02 to 12.07?min. The ranges of other responses, Y₆ and Y₁₂ were 25.72?±?2.85 to 77.14?±?3.42 % and 65.47?±?1.25 to 99.65?±?2.28 %, respectively. Stability studies revealed that no significant change in in vitro floating lag time, total floating time and drug release behavior before and after storage.

Conclusion: It can be concluded that a combination of hydroxypropyl methylcellulose K 15M, sodium carboxy methylcellulose and NaHCO₃ can be used to increase the gastric residence time of the dosage form to improve local effect of metronidazole.     

A kinetic model for the decolorization of C.I. Acid Yellow 23 by Fenton process

The decolorization of azo dye C.I. Acid Yellow 23 (AY23) by Fenton process was investigated. The decolorization rate is strongly dependent on the initial concentrations of the Fe(2+) and H(2)O(2). The optimum operational conditions were obtained at pH 3. A kinetic model has been developed to predict the decolorization of AY23 at different operational conditions by Fenton process. The model allows to simulate the system behavior involving the influence of hydrogen peroxide, Fe(II) and dye concentrations.     

Biosynthesis of titanium dioxide nanoparticles using bacterium Bacillus subtilis

The present study reports a low-cost, new material, eco-friendly and reproducible microbes Bacillus subtilis mediated biosynthesis of TiO₂ nanoparticles. Titanium dioxide nanoparticles synthesized from titanium as a precursor, using the bacterium, B. subtilis. The synthesized nanoparticles were characterized and confirmed as TiO₂ nanoparticles by using the UV spectroscopy, XRD, FTIR, AFM and SEM analysis. The morphological characteristics were found to be spherical, oval in shape, individual nanoparticles as well as a few aggregates having the size of 66–77 nm. The XRD shows the crystallographic plane of anatase of TiO₂ nanoparticles, indicating that nanoparticles structure dominantly correspond to anatase crystalline titanium dioxide.     

Optimization of product and process design for quality and cost

Robust product and process design is an important technique for achieving high quality at low cost. It involves making the product's function much less sensitive to various sources of noise such as manufacturing variation, environmental variation and deterioration. This is a problem in optimization involving minimization of the mean square loss resulting from the deviation of the product's function from its target. Here we show that the optimization can be carried out in two steps: first maximize a quantity called signal-to-noise ratio (S/N) and then bring the performance on target by special adjustment parameters. The two-step procedure works for a wide variety of product functions and makes the optimization process more efficient and practical compared to the direct minimization of the quadratic loss function.     

Optimization of process parameters for synthesis of silica–Ni nanocomposite by design of experiment

The optimum combination of experimental variable, temperature, time of heat treatment under nitrogen atmosphere and amount of Ni-salt was delineated to find out the maximum yield of nanophase Ni in the silica gel matrix. The size of Ni in the silica gel was found to be 34 and 45 nm for the two chosen compositions, respectively. A statistically adequate regression equation, within 95% confidence limit was developed by carrying out a set of active experiments within the framework of design of experiment. The regression equation is found to indicate the beneficial role of temperature and time of heat treatment.     

Optimization of process parameters for the synthesis of silica gel-WC nanocomposite by design of experiment

The optimum combination of experimental variables—composition of the gel matrix, temperature, time of heat treatment under nitrogen atmosphere and percentage excess dextrose has been delineated to find the maximum yield of nanophase WC in the silica gel matrix. The size of WC in the silica gel is found to be 23 nm. A statistically adequate regression equation, for a significance level of 0.05, has been developed by carrying out a set of active experiments within the framework of design of experiment. The regression equation clearly indicates the beneficial role of temperature, time of heat treatment and percentage excess dextrose and the detrimental role of excess alcohol.     

Optimization of cryo-treated EDM variables using TOPSIS-based TLBO algorithm

In order to machine hard and high-strength-to-weight ratio materials, electrical discharge machining (EDM) process is extensively used in aerospace, automobile and other industrial applications. However, high erosion of tool and improper selection of machining variables have emerged as a major obstruction to achieve productivity in this direction. High erosion of tool not only enhances the cost of machining but also increases the machining time by causing interruption during machining. Therefore, proper selection of machining variables and tool material life are the two vital aspects for the tool engineers working in EDM. In view of this, the present work proposes an extensive experimental investigation and optimization of machining variables of cryogenically treated brass tool materials on machining competences of Inconel 718 workpiece. The study primarily highlights the outcome of cryogenically treated soaking duration of tools along with other important process variables, viz. discharge current, open-circuit voltage, pulse-on time, duty factor and flushing pressure, on the performance measures such as electrode wear ratio (EWR), surface roughness and radial over-cut. The study revealed that soaking duration in deep cryo-treatment of the electrode is a significant variable to achieve improved machining characteristics. The performance measures are converted into equivalent single performance measure by calculating the relative closeness coefficient by the techniques for order preferences by similarity to ideal solution (TOPSIS) approach. Finally, a novel teaching–learning-based optimization (TLBO) algorithm has been proposed to find the optimal level of machining variables for the performance measures. The optimal levels of cutting variables obtained through the algorithm are validated through confirmation test, predicting an error of 2.171 percentages between the computational and experimental results. The predicted result suggests that the proposed model can be used to select the ideal process states to achieve productivity for the cryo-treated EDM.     

A partition experimental design for a sequential process with a large number of variables

Statistically designed experiments provide a systematic approach to study and analyze the effects of multiple factors on process performance. In order to improve the performance across an organization, one must investigate multiple processes from supplier to customer. Partition experimental designs provide a design to model several sequential processes simultaneously. The partition design provides the investigator with an efficient design where potential cost and time constraints exist. That is, partition designs are applicable when runs are costly and a large number of variables exist in the serial process. In this paper, we present the application of partition designs using 10 factors in a simulated case study. The design and analysis procedures are discussed, as well as the benefits. Copyright © 2006 John Wiley & Sons, Ltd.     

Production of poly-gamma-glutamic acid by Bacillus subtilis and Bacillus licheniformis with different growth media

Poly gamma-glutamic acid is a naturally occurring homo-polyamide that is made of D- and L-glutamic acid units connected by amide linkages between alpha-amino and gamma-carboxylic groups. Many strains have been studied for the production of poly y-glutamic acid, B. licheniformis 9945a and B. subtilis natto are the two most widely studied strains due to their higher yield. Both of these strains require L-glutamic acid for poly gamma-glutamic acid production. This paper describes investigations on the biosynthesis of poly y-glutamic acid by B. licheniformis 9945a and B. subtilis natto in an automated pH-controlled fermenter. The effect of the growth media such as medium E, F, C and GS was investigated. Medium E produced poly gamma-glutamic acid both with and without MnSO4 in the medium when fermented by B. licheniformis. Presence of MnSO4 in the medium affected both the yield and biomass production. The yield was 12 g/l for the medium containing 2.46 mM MnSO4 whereas it was only 4-5 g/l for the medium without MnSO4 with molecular weight (Mw) of 321,000. Different media such as medium C, F and GS were used for production of poly gamma-glutamic acid by B. subtilis natto. The yield from GS medium was highest and it produced about 26-28 g/l with molecular weight (Mw) of 627,000.     

Optimization of process variables in drilling of carbon fiber reinforced plastics using various multi criteria decision making approaches

Carbon fiber-reinforced polymers are one of the lightweight materials used in structural design due to their exceptional mechanical performances. The drilling operation is indispensable as it facilitates the assembling of various manufactured components. However, drilling of fibrous laminates is deemed difficult in comparison to the traditional metals because of the anisotropic and non-homogeneous nature. The present work addresses the parametric effect on the drilled hole delamination and further reduces it with an optimal combination of parameters for multi-objectives using different multi-criterion decision-making techniques. Initially, the response surface-based regression model of delamination as a function of three static inputs has been developed, further revised with induced thrust as well as mean torque for the improvisation of the prediction capability. Finally, for the overall improvement, a decision-making model has been used that includes grey relation analysis, technique for order performance by similarity to ideal solution, and VIšekriterijumsko Kompromisno Rangiranje method. The delamination was found to be minimum at a low drill point angle (100°), high spindle rotation (2150 min⁻¹ ), and low feed rate (0.025 mm/rev) due to reduced thrust force. The mean absolute prediction error was significantly improved considering root mean square torque rather than axial thrust with process variables.     

The use of artificial neural networks (ANN) for modeling of decolorization of textile dye solution containing C. I. Basic Yellow 28 by electrocoagulation process

In this paper, electrocoagulation has been used for removal of color from solution containing C. I. Basic Yellow 28. The effect of operational parameters such as current density, initial pH of the solution, time of electrolysis, initial dye concentration, distance between the electrodes, retention time and solution conductivity were studied in an attempt to reach higher removal efficiency. Our results showed that the increase of current density up to 80 Am(-2) enhanced the color removal efficiency, the electrolysis time was 7 min and the range of pH was determined 5-8. It was found that for achieving a high color removal percent, the conductivity of the solution and the initial concentration of dye should be 10 mS cm(-1) and 50 mg l(-1), respectively. An artificial neural networks (ANN) model was developed to predict the performance of decolorization efficiency by EC process based on experimental data obtained in a laboratory batch reactor. A comparison between the predicted results of the designed ANN model and experimental data was also conducted. The model can describe the color removal percent under different conditions.     

Passive standoff detection of Bacillus subtilis aerosol by Fourier-transform infrared radiometry

An analysis is presented on the passive standoff detection and identification of Bacillus subtilis (BG) clouds with the Compact ATmospheric Sounding Interferometer (CATSI) sensor. This research is based on recent spectral measurements obtained during the Technology Readiness Evaluation trial held July 2002 at Dugway Proving Ground, Utah. Results obtained from three trial BG cloud episodes are used to explain and demonstrate the detection capability of the CATSI sensor. The BG clouds were measured at a distance of 3 km from the sensor in a near-horizontal path scenario. It was found that the low thermal contrast of approximately 0.2 K between the BG cloud and the background yielded weak but observable spectral signatures. The processing of the spectral signatures with the GASeous Emission Monitoring (GASEM) algorithm has provided a rough estimate of BG cloud column densities. The results of a series of simulations with the FASCOD3 transmission model have shown that the detection sensitivity for BG can be greatly improved for both slant path uplooking and downlooking scenarios.     

Velocity field level-set method for topological shape optimization using freely distributed design variables

The velocity field level-set topological shape optimization method combines the implicit representation in the standard level-set method and the capabilities of general mathematical programming algorithms in handling multiple constraints and additional design variables. The key concept is to construct the normal velocity field using basis functions and the velocity design variables at specified points (referred to as velocity knots) in the entire design domain. In this study, the velocity design variables are decoupled from the level-set grid points. Making use of this property, we can adaptively change the arrangement of the velocity knots as the structural boundary evolves. This provides more design freedom in the optimization and allows for a significant reduction in the number of design variables. Several numerical examples in two- and three-dimensional design domains are presented to demonstrate the robustness and efficiency of the proposed method. We also show that changing the number of velocity knots may implicitly exert certain control on topological complexity and length scale.     

Kinetic analysis of C.I. Acid Yellow 9 photooxidative decolorization by UV-visible and chemometrics

A kinetic study of the C.I. Acid Yellow 9 photooxidative decolorization process, using H(2)O(2) as oxidant, was carried out by chemometric analysis of the UV-visible data recorded during the process. The number of chemical species involved in the photooxidative decolorization process was established by singular value decomposition (SVD) and evolving factor analysis (EFA). Information about the different chemical species along the process was obtained from the spectral and concentration profiles recovered by soft multivariate curve resolution with alternating least squares (MCR-ALS). This information was complemented by mass spectrometry (MS) to postulate a reaction pathway. The dye photooxidative decolorization process involved consecutive and parallel reactions. The consecutive pathway consists of a first stage of dye oxidation followed by the rupture of the azo linkage to form smaller molecules that are degraded in a subsequent stage. The parallel reactions form products that are undetectable in the UV-visible spectra. Kinetic constants of the reactions postulated in the photooxidative process were retrieved by applying a hybrid hard and soft MCR-ALS resolution. All constants were similar for the consecutive stages and higher than those obtained for the parallel reactions.     

解淀粉芽孢杆菌高密度发酵条件的优化

该文探讨解淀粉芽孢杆菌(B.amyloliquefaciens)1841的高密度工业发酵工艺优化,为解淀粉芽孢杆菌的工业化生产提供依据。以平板菌落直径、及培养后的活菌浓度为指标,对种子的保存方法、活化方式和培养基、发酵培养基中的酵母粉和大豆蛋白粉用量以及发酵的后期调控进行筛选和优化。筛选出最佳的工业菌种保存条件为30%甘油为保护剂,-64℃保存;最佳活化方法为采用PDA培养基活化,并经过一次48 h活化和24 h二次活化;最佳的转菌时间为在种子培养后17~18 h。最佳的酵母粉和大豆蛋白粉浓度分别为20 g/L和40 g/L,发酵的后期调控需要进行补料和流加氨水将p H控制在7.0±0.2,发酵时间延长至72 h。通过对发酵的基本条件进行筛选和优化,得到可在100 L发酵罐上进行高密度发酵的体系,发酵浓度可达常规发酵的100倍(1×1014CFU/m L)。     

A facile synthesis of silver nanoparticle with SERS and antimicrobial activity using Bacillus subtilis exopolysaccharides

In this study, we report a facile synthesis of silver nanoparticle having SERS and antimicrobial activity using bacterial exopolysaccharide (EPS). Bacillus subtilis (MTCC 2422) was grown in nutrient broth and the extracellular EPS secreted by the organism was extracted and purified. The purified EPS was used for the synthesis of silver nanoparticles. The kinetics of silver nanoparticle synthesis was deduced by varying the exposure time and the concentration of EPS. The rate constant (k) for the synthesis of silver nanoparticle was calculated from the slope of ln(A^∞ ? A^t) versus time plot. The k value was found to be 3.49 × 10^?3, 5.81 × 10^?3 and 5.03 × 10^?3 per min for particle synthesis using 2, 5 and 10 mg/mL EPS, respectively. The nanoparticles synthesised had an average particle size of 5.18 ± 1.49 nm, 1.96 ± 0.77 nm and 2.08 ± 0.88 nm for 2, 5 and 10 mg/mL EPS, respectively. The synthesised particles were characterised using UV-Vis absorbance spectroscopy, high-resolution transmission electron microscopy (HRTEM) attached to EDS (energy dispersive spectroscopy), Fourier transform infrared spectroscopy (FTIR), surface enhanced Raman spectroscopy (SERS) and zeta potential analyser. To our knowledge, this is the first study to report SERS activity of microbial Bacillus subtilis EPS-based synthesis of silver nanoparticle. HRTEM images showed silver nanoparticle entrapped in polysaccharide nanocages. Silver nanoparticle showed higher adherence towards the bacterial surface, with good bactericidal activity against Pseudomonas aeroginosa and Staphylococcus aureus.     

Algorithm for determining classes of indistinguishable faults by using linguistic variables

We construct an algorithm that uses linguistic variables for determining classes of undistinguishable faults. Translated from Izmeritel'naya Tekhnika, No. 8, pp. 27–28, August, 2000.     

Biological synthesis of gold and silver nanoparticles mediated by the bacteria Bacillus subtilis

Biological synthesis of gold and silver nanoparticles was carried out using the bacteria Bacillus subtilis. The reduction processes of chloroaurate and silver ions by B. subtilis were found to be different. Gold nanoparticles were synthesized both intra- and extracellularly, while silver nanoparticles were exclusively formed extracellularly. The gold nanoparticles were formed after 1 day of addition of chloroaurate ions, while the silver nanoparticles were formed after 7 days. The nanoparticles were characterized by X-ray diffraction, UV-vis spectra and transmission electron spectroscopy. X-ray diffraction revealed the formation of face-centered cubic (fcc) crystalline gold nanoparticles in the supernatant, broth solution and bacterial pellet. Silver nanoparticles also exhibited diffraction peaks corresponding to fcc metallic silver. UV-vis spectra showed surface plasmon vibrations for gold and silver nanoparticles centered at 530 and 456 nm, respectively. TEM micrographs depicted the formation of gold nanoparticles intra- and extracellularly, which had an average size of 7.6 +/- 1.8 and 7.3 +/- 2.3 nm, respectively, while silver nanoparticles were exclusively formed extracellularly, with an average size of 6.1 +/- 1.6 nm. The bacterial proteins were analyzed by sodium dodecyl sulfonate-polyacrylamide electrophoresis (SDS-PAGE) before and after the addition of metal ion solutions. We believe that proteins of a molecular weight between 25 and 66 kDa could be responsible for chloroaurate ions reduction, while the formation of silver nanoparticles can be attributed to proteins of a molecular weight between 66 and 116 kDa. We also believe that the nanoparticles were stabilized by the surface-active molecules i.e., surfactin or other biomolecules released into the solution by B. subtilis.