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Material Extrusion (MEX), particularly Fused Filament Fabrication (FFF), is the most widespread among the additive manufacturing (AM) technologies. To further its development, understanding the influence of the various printing parameters on the manufactured parts is required. The effects of varying the infill percentage, the number of layers of the top and bottom surfaces and the number of layers of the side surfaces on the tensile properties of the printed parts were studied by using a full factorial design. The tensile test results allowed a direct comparison of each of the three parameters' influence on the tensile properties of the parts to be conducted. Yield strength appears to be the most affected by the number of layers of the top and bottom surfaces, which has twice the impact of the number of layers of the side surfaces, which is already twice as impactful as the infill percentage. Young's modulus is the most influenced by the number of layers of the top and bottom surfaces, then by the infill percentage and finally by the number of layers of the side surfaces. Two mathematical models were considered in this work. The first one was a polynomial model, which allowed the yield strength to be calculated as a function of the three parameters mentioned previously. The coefficients of this model were obtained by performing tensile tests on nine groups of printed samples, each with different printing parameters. Each group consisted of three samples. A second simplified model was devised, replacing the numbers of layers on the side and top/bottom surfaces with their fractions of the cross-section surface area of the specimen. This model provided results with a better correlation with the experimental results. Further tests inside and outside the parameter ranges initially chosen for the model were performed. The experimental results aligned well with the predictions and made it possible to assess the accuracy of the model, indicating the latter to be sufficient and reliable. The accuracy of the model was assessed through the R2 value obtained, R2 = 92.47%. This was improved to R2 = 97.32% when discarding material infill as an input parameter. [ABSTRACT FROM AUTHOR]

This paper aims to show through a factorial experimental design significant factors on the polymeric bushing wear PA66, including their amplitude, frequency and spring height, when interacting with a steel axle SAE1018 (from Society of Automotive Engineers - SAE) in a tension belt applied. It was verified that factors as amplitude and frequency are significant and it was possible to propose a mathematical model to predict this wear behaviour for the proposed test. Moreover, an adhesion wear behaviour was verified, whereof a polyamide film was observed on the axle transferred by the bushing. Through the microscopy report analysis, it was possible to see the transfer film topology characterisation for a better comprehension of the adhered polyamide film from the bushing to the axle surface. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles have been of great interest due to their physical and chemical properties, and the coprecipitation method is among the main ways to produce them. Despite being the cheapest and most straightforward method, its main disadvantage during the scale-up process is the increase in the nanoparticle's polydispersity and the reactor's dimensions. This way, looking for an alternative to increasing the production scale in the synthesis of Fe3O4 by coprecipitation, we developed and optimized a low-cost flow reactor based on peristaltic pumps made of inexpensive DC motors and an Arduino microcontroller. A 24–1 experimental design was performed to optimize the Fe3O4 coprecipitation parameters such as reagent concentration, flow rate, and reactor size. The flow reactor parameters were verified to affect the size, homogeneity, and stability of Fe3O4 nanoparticles with sizes ranging from 5 to 10 nm and polydispersity index varying between 0.15 and 0.45 Furthermore, the product was synthesized in a matter of minutes with rates up to 150 mL min−1 in a low-cost reactor. [ABSTRACT FROM AUTHOR]

Strategies for improving the performance of solar cells have been the focus of several researchers. The evaluation of the effects resulting from the variation in assembly parameters was the approach adopted in this study. Three construction parameters of a dye-sensitized solar cell were varied, and an experimental factorial design method was used to analyze these modifications simultaneously, verifying the photovoltaic results. The modifications were conducted for the semiconductor area (Factor A), substrate area (Factor B), and semiconductor composition (Nb2O5 with/without TiO2) (Factor C). The curves of the current density versus voltage (J–V) were analyzed to evaluate the effects of the variations of each parameter and their combined interactions. The change related to the semiconductor composition (Factor C) was statistically significant, being relevant to improve the photovoltaic parameters evaluated. The current density, on average, increased 93.12% in the cells with the change in the semiconductor composition. Similarly, the average increase in open-circuit voltage in the respective cells was 28.71%. The reason that Factor C was predominant was attributed to the uniformity of the semiconductor layer observed by results of scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

The current work describes the development and validation of a stability‐indicating UPLC method for the determination of olmesaratan medoxomil (OLM), amlodipine besylate (AMB), hydrochlorothiazide (HCT) and their degradation products in the triple‐combination tablet dosage form. The separation was achieved using a Zorbax Eclipse plus C8 RRHD (100 mm × 3.0 mm), 1.8 μm column with gradient elution of mobile phase A containing 0.02 m of sodium phosphate buffer (pH 3.35) and mobile phase B as acetonitrile and water (90:10, v/v). The detector signal was monitored at UV 250 nm. Analytical performance of the optimized UPLC method was validated as per International Conference on Harmonization guidelines. The linearity ranges for OLM, AMB and HCT were 0.59–240, 0.30–60 and 0.37–150 μg/ml, respectively, with correlation coefficients >0.999. The dosage form was subjected to forced‐degradation conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal and photodegradation. The method was proved to be stability indicating by demonstrating the specificity of the drugs from degradation products. The robustness of the method was evaluated through a two‐level, three‐factorial design with a multivariate approach. Statistical data analysis with best model fit P‐value < 0.05 from an ANOVA test indicated that the influence of individual factors is relatively higher than the interaction effects. The method is useful for the analysis of drug products. [ABSTRACT FROM AUTHOR]

Manganese is a critical metal for the steelmaking industry, and it is expected that its world demand will be increasingly affected by the growing market of lithium-ion batteries. In addition to the increasing importance of manganese, its recycling is mainly determined by trends in the recycling of iron and steel. The recovery of manganese by solvent extraction has been widely investigated; however, the interaction of different variables affecting the process is generally not assessed. In this study, the solvent extraction of manganese from a solution based on lithium-ion batteries was modeled and optimized using factorial designs of experiments and the response surface methodology. Under optimized conditions (O:A of 1.25:1, pH 3.25, and 0.5 M bis(2-ethylhexyl) phosphoric acid (D2EHPA)), extractions above 70% Mn were reached in a single extraction stage with a coextraction of less than 5% Co, which was mostly removed in two scrubbing stages. A stripping product containing around 23 g/L Mn and around 0.3 g/L Co can be obtained under optimized conditions (O:A of 8:1, 1 M H2SO4 and around 13 min of contact time) in one stripping stage.

Graphical abstract Highlights • Inclusion of β-spodumene particles into impurities reduce Li extraction by 2.0%. • Impurity leaching is evaluated to be approximately 0.5 at% of spodumene concentrate. • Residual sulfuric acid excess is approximately 7–13%. • Sulfuric acid excess and duration are the most important parameters for Li leaching. • Impact of mechanical stirring is real and could improve lithium recovery by 0.3%. Abstract The H 2 SO 4 roasting for the lithium extraction from β-spodumene concentrate has been the traditional process since the middle of the twentieth century (Ellestad and Leute, 1950) and is the preferred one for new producers due to its economic viability and high purity product to supply the growing lithium-ion batteries market. Unfortunately, very few studies have tried to determine the fundamental causes why lithium extraction is limited to 90% and the need for more than 30% stoichiometric excess of H 2 SO 4. Acid roasting of β-spodumene was carried out in a rotary tube furnace followed by lithium leaching to complete a factorial design of experiments studying H 2 SO 4 stoichiometric excess (30% vs 20%), roasting temperature (250 °C vs 225 °C), roasting duration (30 min vs 5 min) and mechanical stirring amplified by the use of 35 alumina beads of 6.35 mm diameter. An analysis of variance was made on lithium and impurity leaching and a principal component analysis on impurity leaching. These statistical analyses showed the dependence and independence respectively of lithium and impurity extraction on operating parameters. The extraction percentages of impurities (Al, Na, Fe, Ca, Mn and K) were quite low with a total of 0.5 at% of the spodumene concentrate being leached. H 2 SO 4 excess, temperature, duration and mechanical stirring respectively improve the lithium recovery by 0.8%, 0.0%, 1.0% and 0.3%. Residual H 2 SO 4 excess was estimated to be 7–13%. These observations point to negate, at least for low impurity concentrates, the hypothesis of sulfuric acid consumption by impurities as a reason for the need of stoichiometric excess as high as 30%. Nonetheless, it was demonstrated that lithium extraction decreases with the impurity content in the feed material. This suggests that lithium recovery may be limited by the impurity coating of some β-spodumene particles. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus has become the most common opportunistic microorganism related to nosocomial infections due to the bacteria capacity to form biofilms on biomedical devices and implants. Since bacterial adhesion is the first step in this pathogenesis, it is evident that inhibiting such a process will reduce the opportunity for bacterial colonization on the devices. This work is aimed at optimizing a surface biofunctionalization strategy to inhibit the adhesion of S. aureus on solid substrates. The first part of the work deals with the albumin adsorption-desorption process, studied by a factorial design of experiments to explore a wide range of experimental factors (protein concentration, pH, flow rate and adsorption time) and responses (initial adsorption rate, adsorbed amount, desorbed extent) for hydrophilic and hydrophobic substrates, with a reduced number of experiments. This approach allows the simultaneous evaluation of the factors affecting the albumin adsorption-desorption process to find a qualitative correlation with the amount of alive S. aureus adhered on albumin biofunctionalized substrates. The results of this work point to a relationship between bacterial adhesion and the degree of albumin relaxation on the solid substrate. In fact, the inhibition of bacterial adhesion on albumin biofunctionalized substrates is due to the surface perturbation on the native structure of the protein. On this base, a biofunctionalization strategy was designed using a solution of thermally treated albumin molecules (higher β-sheet or unordered secondary structure elements) to biofunctionalize solid substrates by dipping. With these albumin biofunctionalized substrates S. aureus adhesion was minimized. [ABSTRACT FROM AUTHOR]

Betacyanin is the red-violet pigment possesses potent antiradical and antioxidant properties. Globally, natural colorants have gained much interest than synthetic colours due to their adverse ill effects. The study aimed to assess membrane technology for the concentration of betacyanin pigment from cactus pear employing forward osmosis. The effect of process parameters such as feed and osmotic agent solution (OAS) flowrate and temperature on betacyanin concentration was investigated using factorial design. Maximum concentration of betacyanin was obtained with 150 mL/min feed flowrate, 50 °C feed temperature, 150 mL/min OAS flowrate and 50 °C OAS temperature. Further, sodium chloride was the best OAS that concentrated betacyanin from 898 to 1325 mg/L with a transmembrane flux of 1.13 L/m2 h. Physico-chemical characteristics imply high retention of antioxidant activity and other nutrients during concentration process. The results revealed the suitability of forward osmosis for the concentration of betacyanin from Opuntia ficus-indica using cellulose acetate membrane. [ABSTRACT FROM AUTHOR]

Nowadays, landfill leachates are one of the most critical environmental issues faced by countries around the world. They result from the percolation of rain water through layers of solid waste, to which is added water from biochemical processes in waste's cells and water that comes from wastes themselves. They are therefore highly charged with organic and mineral matter, which requires treatment before discharge to the receiving environment. In recent years, many techniques have been developed for leachate treatment. In this study, landfill leachate selected comes from Rabat city's landfill. Landfill leachate is treated by anaerobic combined with coagulation flocculation (CF) process, using ferric chloride as coagulant and a cationic polymer as flocculant. The leachate is characterized by high COD and BOD5. The BOD5/COD ratio is equal to 0.58 ± 0.01, revealing that it is a young leachate with a very important biodegradability. The leachate was also loaded with phenolic compounds whose concentration reached 341.6 ± 21.3 mg/L. The optimization of the doses of coagulant and flocculant was performed using factorial design of experiments. Optimal dosages obtained were: 4.4 g/L of coagulant and 9.9 mL/L of flocculant. Removal efficiencies reached: 89 ± 6, 69 ± 4.8, 94 ± 1.3, 80 ± 8.7 and 89 ± 1.2% for phenol, turbidity, color, COD and absorbance at 254 nm (Abs 254 nm) respectively. [ABSTRACT FROM AUTHOR]

Identification of significant process parameters using experiments needs to be carefully formulated as it can be a resourcedemanding process. Using appropriate statistical techniques such as the Taguchi method of factorial design of experiments,the number of necessary experiments can be reduced and the statistical significance of parameters can be safely identified.In the case of linear friction welding it was found that the frequency of oscillation, power input and forging pressure arestatistically insignificant for the range of friction pressures studied.

The dental wastewater can contribute to the total daily mercury load on the environment. Factorial design of experiments is useful to analyze factors that influence this solubility. The aim of the present study was to design experiments to examine the effects ofoperational variables, humic acid, temperature, pH and contact time that may affect the solubility of total mercury as dental amalgam residue in reduction process. Based on the factorial design of experiments, the humic acid concentration was the most significant factor in this process, followed by other factors. The parameters affecting the solubility of total mercury showed that when the [HA], T and CT increases and pH decreases there is an important increase of total mercury concentration in process. For the tested conditions, thehigh total mercury concentration was obtained using the humic acid concentration = 1.0 g L-1, temperature = 35oC, pH = 4.0 and contact time = 10 days.O esgoto odontológico pode contribuir na carga total de mercúrio noambiente. O estudo do planejamento experimental é útil para analisar os fatores que influenciam nesta solubilidade. O objetivo deste trabalho foi realizar um planejamento experimental para analisar os efeitos das variáveis operacionais, ácido húmico, temperatura,pH e tempo de contato, que podem afetar a solubilidade do mercúrio total como amálgama odontológico em um processo de redução. Baseado no planejamento experimental, a concentração de ácido húmico foi o fator mais significativo no processo, seguido dos demais fatores. Os parâmetros que afetam a solubilidade do mercúrio total mostram que quando a [AH], T e TC aumentam e o pH diminui há um aumento significativo na concentração de mercúrio total no processo. A maior concentração de mercúrio total foi obtido nas condições de concentração de ácido húmico = 1,0 g L-1, temperatura = 35oC, pH = 4,0 e tempo de contato = 10 dias.

This work focuses on experimental and numerical investigation of the deflection on VAWT blade surface against the high measured wind speeds that were simulated in FLUENT to obtain the corresponding static forces. The effect of forces, blade setting angle and thickness to chord ratio along with their combined effects on deflection were assessed experimentally and numerically. Three airfoils of gradually increasing thickness to chord ratio, NACA 0015, 0021 and 4412, were selected along with three levels of forces and tested at 5°, 10° and 15° of blade setting angle. A 3 factorial experimental design was used to perform experiments and Analysis of variance (ANOVA) confirmed that individual effects of force and thickness to chord ratio were the most significant factors while blade setting angle had lesser significance on deflected values. However, interactive effects of these parameters were significant. Minimum deflections were observed in the range of 0.25-0.28 mm on NACA 0021 at 3 kg force in combination with all blade setting angles. Maximum observed value of defection was 1 mm, which occurred at 9 kg force at 5°, 10° and 15° of blade setting angle on NACA 0015 and 4412 airfoil shapes. The results ensure that the blade structure remains stable at 9 kg which corresponds to 20 m/s wind speed without affecting the performance. The deflections obtained from Finite element method were compared with experimental results and found in good agreement with each other. [ABSTRACT FROM AUTHOR]

The prediction of temperature distribution is a critical process in the study of welding thermal field. Therefore, the accuracy in temperature measurement is quite important to provide meaningful results and to establish the coupling among thermal field results and other studies in welding as mechanical and microstructural analyses. This work deals with statistical analysis and design of experiments (DoE) in order to establish an optimal experimental design for thermal history measurements in welding processes with thermocouples independent of base material. Calculations from theoretical correlations and computational modeling of heat flow were used to accomplish the present study. The Gas Tungsten Arc Welding process (GTAW) was used in the experiments along with plates of a structural steel (ASTM A 36) and a martensitic stainless steel (AISI CrMo 12-1). Four different parameters were studied related with the disposition, separation, depth, thermocouple arrangement and application of thermal paste. An optimal design was able to measure the maximum temperatures in adjacent zones to the weld bead, which are important for the study of welding thermal behavior. [ABSTRACT FROM AUTHOR]

This study investigated the possibility of cleaning Malatya-Arguvan lignite using the flotation method. Because preliminary flotation studies suggested that desliming affects flotation performance, an attempt was made to quantify the effects of the major influencing parameters on the effectiveness of desliming and flotation. Because the optimum collector dosage was found to be very high, the effects of addition of sodium oleate and Aero 3477 were also investigated, to reduce the collector dosage. However, flotation results showed that the addition of sodium oleate and Aero 3477 does not alter the collector dosage significantly. Despite all the aforementioned efforts, only 20% of feed ash could be removed. [ABSTRACT FROM PUBLISHER]

Surrogate modeling is widely used in many engineering problems. Data sets often have Cartesian product structure (for instance factorial design of experiments with missing points). In such case the size of the data set can be very large. Therefore, one of the most popular algorithms for approximation-Gaussian Process regression-can be hardly applied due to its computational complexity. In this paper a computationally efficient approach for constructing Gaussian Process regression in case of data sets with Cartesian product structure is presented. Efficiency is achieved by using a special structure of the data set and operations with tensors. Proposed algorithm has low computational as well as memory complexity compared to existing algorithms. In this work we also introduce a regularization procedure allowing to take into account anisotropy of the data set and avoid degeneracy of regression model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microwave-assisted method is suitable for obtaining Fe-Nb 2 O 5 at low temperatures. • The photocatalytic performance for the discoloration of rhodamine B was evaluated. • The 1% Fe-Nb 2 O 5 sample showed the best photocatalytic discoloration result. • A 24 factorial design experiment was performed analyzing different variables. • Factorial design helps to find the best routes to perform photocatalysis. Nb 2 O 5 and Fe inserted Nb 2 O 5 from 1 to 3 % were synthesized by the microwave-assisted hydrothermal method. The XRD results confirm the presence of Nb 2 O 5 with low crystallinity in all samples, which is characteristic of the material that was not subjected to heat treatment. The SEM images show that the insertion of Nb 2 O 5 with Fe promotes the formation of pores on the surface of the material. The addition of Fe also led to a decrease in the band gap to pure Nb 2 O 5. The photocatalytic performance for the degradation of rhodamine B was evaluated. The 1 %Fe-Nb 2 O 5 sample showed the best photocatalytic discoloration result, achieving 100 % discoloration of RhB within 60 min. The increase in ion concentration leads to a decrease in photocatalytic performance. A 24 factorial design experiment was performed for samples of Nb 2 O 5 and Nb 2 O 5 with 1 %Fe-Nb 2 O 5. The study variables were catalyst type (Nb 2 O 5 and 1 %Fe-Nb 2 O 5), catalyst dosage (25 and 50 mg), pH of the RhB solution (5 and 10), and time of photocatalytic analysis (30 and 60 min) to check the effect on the RhB discoloration. The analysis showed that the change in catalyst, catalyst dosage, pH and reaction time had a significant effect. Most of the interactions between the variables also had a significant effect on the process, both positively and negatively. The diversification of the results of the factorial design, variables, and their interactions allowed us to identify the best execution routes of heterogeneous photocatalysis for the removal of RhB, depending on the parameters used in this work. [ABSTRACT FROM AUTHOR]

In this work it was implemented a numerical model that simulates the process of orthogonal machining of metallic materials by means of the Finite Elements Method (FEM). For the development of the model, the program Ansys Flotran was used. The material was simulated as a high viscosity fluid crashing against a solid with the cutting edge geometry. From the numerical model it was made a factorial fractionated design of experiments using Minitab software, where the selected input variables were: cutting speed, depth of cut, rake angle, density and viscosity of the fluid. The considered output variables were the velocity of chip and the position of the stagnation point. Two functional metamodels of the FEM model were made, the first one by determining the empirical equations by means of a linear regression. The second was made by establishing functions based on fuzzy logic. The experiments with both metamodels showed that the depth of cut and the rake angle have the greater influence in the chip speed and in the position of the stagnation point. The metamodel based on fuzzy logic presented a better representation between the input and output variables.

In this work it was implemented a numerical model that simulates the process of orthogonal machining of metallic materials by means of the Finite Elements Method (FEM). For the development of the model, the program Ansys Flotran was used. The material was simulated as a high viscosity fluid crashing against a solid with the cutting edge geometry. From the numerical model it was made a factorial fractionated design of experiments using Minitab software, where the selected input variables were: cutting speed, depth of cut, rake angle, density and viscosity of the fluid. The considered output variables were the velocity of chip and the position of the stagnation point. Two functional metamodels of the FEM model were made, the first one by determining the empirical equations by means of a linear regression. The second was made by establishing functions based on fuzzy logic. The experiments with both metamodels showed that the depth of cut and the rake angle have the greater influence in the chip speed and in the position of the stagnation point. The metamodel based on fuzzy logic presented a better representation between the input and output variables. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays, lignocellulosic agricultural wastes are regarded as alternative source of renewable raw materials. This study is based in the hemicellulosic monomers conversion into furfural using different acid catalysts and microwave technology. In this work, liquors with high content in hemicelluloses obtained from corn cobs autohydrolysis were treated with sulfuric acid and hydrochloric acid as catalysts, in order to obtain the optimum conditions for furfural production. Optimum conditions were determined using experimental designs in which catalyst concentrations, temperature and time of reactions were varied. The results showed that the furfural production was strongly influenced by catalyst concentration, time and temperature of the reaction. Highest furfural yields (37.06% respects to the total hemicelluloses contained in the initial raw material) were reached using HCl as catalyst at medium acid concentration, medium temperature and high time of reaction. [Copyright &y& Elsevier]

Abstract: Cement mortars prepared with steatite particles have been investigated for restoration of sculptures and other craftworks. This work investigates the addition of a thermoset polymer into cement-based composites reinforced with residues of steatite particles in order to seal the open pores, reduce water penetration and thus enhancing the material''s lifetime. A full factorial design of 2141 type was carried out to investigate the effect of the steatite particle size and polymeric fraction on the physical and mechanical properties of the composite materials, such as bulk density, apparent porosity, elastic modulus and compressive strength. Scanning electron microscopy (SEM) was used to reveal features in the microstructure that are related to the physical properties. Results have shown that highest compressive strength (43MPa) and lowest apparent porosity (0.19%) are achieved when steatite particles are coarser (ranging from 1.41mm to 0.42mm) and 40% of polymeric phase is employed. The composite with best performance also presented texture and colour quite similar to the surface characteristics of the natural soap-stone, which makes it suitable for restoration purposes. [Copyright &y& Elsevier]

Abstract: This present investigation deals with the development and optimization of polymeric nanoparticle systems loaded with 3,5,3'-triiodothyroacetic acid (Triac). A 211-6 fractional factorial design and another 22 factorial design were used to study the contrasts on particle size distribution, morphology, surface charge, drug content, entrapment efficiency, and in vitro drug release profiles. The independent variables were the concentration of Triac, type and quantity of both polymer and oil, quantity of Span™ 60 and Tween® 80, volume of solvent and water, and velocity of both magnetic stirring and the transfer of the organic phase into the aqueous solution. The results of optimized formulations showed a narrow size distribution with a polydispersity index lower than 0.200. The particle sizes were on average 159.6 nm and 285.6 nm for nanospheres and nanocapsules, respectively. The zeta potential was higher than 20 mV (in module) and the entrapment efficiency was nearly 100%. A high-performance liquid chromatography method was developed, validated, and efficiently applied to Triac quantification in colloidal suspension. The main independent variables were the type and quantity of the polymer and oil. In vitro drug release profile depicted several features to sustain Triac release. Different formulations showed various release rates indicating an interaction between Triac and other formulation compounds such as polymer and/or oil quantity. Two different models were identified (biexponential and monoexponential) that allowed the control of both the release rate and Triac concentration. Thus, the prepared nanoparticles described here may be of clinical importance in delivering Triac for thyroid treatment [ABSTRACT FROM AUTHOR]

Abstract: The photocatalytic degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) and simazine (2-chloro-4,6-diethylamino-1,3,5-triazine) herbicides widely used in agriculture has been investigated. Experimental design methodology was used to assess the influence of pH and TiO2 concentration and the efficiency of the process. The results indicated that in the experimental domain investigated TiO2 concentration was the most significant factor in contrast to the scarce influence shown by the initial pH. The mechanism of atrazine and simazine photocatalytic degradation was studied under the experimental conditions determined as optimal. No full mineralization of atrazine or simazine was achieved. The main intermediates occurring during the reaction were identified by high performance liquid chromatography (HPLC). Based on the concentration profile of intermediates formed during the treatment a degradation pathway is proposed for each herbicide. The toxicity along the reaction was monitored by means of luminescence bioassays using Vibrio fischeri. The inhibition percentage decreases with the irradiation times what can be associated with the formation of highly hydroxylated intermediates. [Copyright &y& Elsevier]

The factorial design of experiments and desirability function approach has been applied for multi-response optimization in pervaporation separation process. Two organic aqueous solutions were considered as model mixtures, water/acetonitrile and water/ethanol mixtures. Two responses have been employed in multi-response optimization of pervaporation, total permeate flux and organic selectivity. The effects of three experimental factors (feed temperature, initial concentration of organic compound in feed solution, and downstream pressure) on the pervaporation responses have been investigated. The experiments were performed according to a 23 full factorial experimental design. The factorial models have been obtained from experimental design and validated statistically by analysis of variance (ANOVA). The spatial representations of the response functions were drawn together with the corresponding contour line plots. Factorial models have been used to develop the overall desirability function. In addition, the overlap contour plots were presented to identify the desirability zone and to determine the optimum point. The optimal operating conditions were found to be, in the case of water/acetonitrile mixture, a feed temperature of 55°C, an initial concentration of 6.58% and a downstream pressure of 13.99kPa, while for water/ethanol mixture a feed temperature of 55°C, an initial concentration of 4.53% and a downstream pressure of 9.57kPa. Under such optimum conditions it was observed experimentally an improvement of both the total permeate flux and selectivity. [Copyright &y& Elsevier]

Identification of significant process parameters using experiments needs to be carefully formulated as it can be a resource demanding process. Using appropriate statistical techniques such as the Taguchi method of factorial design of experiments, the number of necessary experiments can be reduced and the statistical significance of parameters can be safely identified. In the case of linear friction welding it was found that the frequency of oscillation, power input and forging pressure are statistically insignificant for the range of friction pressures studied. [ABSTRACT FROM AUTHOR]

An indigenous mixed culture of microorganisms, isolated from a sewage treatment plant, was investigated for its potential to simultaneously degrade phenol and m-cresol during its growth in batch shake flasks. 22 full factorial designs with the two substrates as the factors, at two different levels and two different initial concentration ranges, were employed to carry out the biodegradation experiments. For complete utilisation of phenol and m-cresol, the culture took a minimum duration of 21 hrs at their low concentration of 100 mg/L each, and a maximum duration of 187 hrs at high concentration of 600 mg/L each in the multisubstrate system. The biodegradation results also showed that the presence of phenol in low concentration range (100-300 mg/L did not inhibit m-cresol biodegradation; on the other hand, presence of m-cresol inhibited phenol biodegradation by the culture. Moreover, irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. During the culture growth, a lag phase was observed above a combined concentration of 500 mg/L i.e., 200 mg/L m-cresol and 300 mg/L of phenol and above). Statistical analysis of the specific growth rate of the culture in the multisubstrate system was also performed in the form of ANOVA and Student 't' test, which gave good interpretation in terms of main and interaction effects of the substrates. [ABSTRACT FROM AUTHOR]

A factorial experimental design technique was used to investigate the biosorption of reactive red RGB (λ max =521nm) from water solution on rice husk treated with nitric acid. Biosorption is favored because of abundance of biomass, low cost, reduced sludge compared to conventional treatment techniques and better decontamination efficiency from highly diluted solutions. Factorial design of experiments is employed to study the effect of four factors pH (2 and 7), temperature (20 and 40), adsorbent dosage (5 and 50mg/L) and initial concentration of the dye (50 and 250mg/L) at two levels low and high. The efficiency of color removal was determined after 60min of treatment. Main effects and interaction effects of the four factors were analyzed using statistical techniques. A regression model was suggested and it was found to fit the experimental data very well. The results were analyzed statistically using the Student''s t-test, analysis of variance, F-test and lack of fit to define most important process variables affecting the percentage dye removal. The most significant variable was thus found to be pH. [Copyright &y& Elsevier]

Abstract: Hereafter, a modification of the traditional Palmes diffusion tube by fitting a membrane at the open end of the tube is presented. The membrane is placed to avoid the effect of turbulence due to wind speed. Further optimisations of the volume of absorbent and number of meshes retaining the absorbent are also described. Finally, the sampler is placed in an air proof container and is ready to use in order to improve the quality of measurement. In order to evaluate the performance of the membrane-closed Palmes diffusion tube to monitor nitrogen dioxide (NO2), experiments were carried out in an exposure chamber. The relative effect of NO2, temperature, humidity, averaging time and wind speed on the uptake rate of the sampler were then studied. Among the uncontrolled variables, temperature and humidity are found to be the most important ones leading to variability of the uptake rate. Two equations, used to estimate the uptake rate are established. These equations were then applied on some field data and laboratory inter-comparison tests. The agreement between the chemiluminescence method and diffusive samplers changes from 20% of mean bias with the traditional Palmes diffusion tubes to 5% of mean bias with the membrane-closed Palmes tube (MCPT) at the same monitoring site. In the laboratory inter-comparison, the MCPT has shown to be able to correctly measure NO2 under two extreme exposure conditions in contrast with other diffusive samplers. The uncertainty of the sampler is evaluated. It fulfils the European Directive data quality objective of 25% for accuracy and therefore the sampler qualifies as an indicative method for NO2 monitoring. [Copyright &y& Elsevier]

In this article, a subtractive clustering-based fuzzy identification method and a Sugeno-type fuzzy inference system are used for modeling in metal cutting. This approach is considered with its application on the experimental study of Boring and Trepanning Association (BTA) deep-hole drilling. The model for the surface roughness is identified by using the cutting speed and feed as input data and roughness as the output data. Using subtractive clustering in both input and output spaces performs the model-building process. Minimum error model is obtained through enumerative search of clustering parameters. The fuzzy model obtained is capable of predicting the surface roughness for a given set of inputs (speed and feed). Therefore, the operator can predict the quality of the surface for a given set of working parameters and will then be able to set the machining parameters to achieve a certain surface quality. The fuzzy model is verified experimentally by further experimentation using different sets of inputs. The tool life is also investigated using the same approach. The fuzzy inference system obtained is capable of predicting the tool life for a given set of cutting parameters. Therefore, the operator will be able to predict how many minutes the cutting tool is going to last and will set the time for the next tool change. [ABSTRACT FROM AUTHOR]

Batch adsorption equilibrium of the dye Rhodamine 6G, using activated carbon beads incorporated with calcium alginate (ACCA beads), was studied. The effects of several factors governing the adsorption process, such as dye concentration (100–300 mg/l), pH (7–9), and temperature (30–60°C), on percent of adsorption were investigated at a fixed dosage of ACCA beads (1 g/l). High percentages of adsorption of Rhodamine 6G were obtained using ACCA beads. Based on the analysis of variance and the factorial design of experiments, dye concentration was the most significant factor under the experimental ranges examined. [Copyright &y& Elsevier]