Production of active lipase by Rhizopus oryzae from sugarcane bagasse: solid state fermentation in a tray bioreactor

This study deals with production of lipase in solid state fermentation by Rhizopus oryzae from sugarcane bagasse. A tray bioreactor was designed for the extracellular enzyme production. Daily, lipase production was evaluated at several incubation temperatures. Furthermore, the influence of temperature and humidity of the cabinet, depth of solid bed, particle size, initial moisture content and supplementary substrate (olive oil) as carbon source was investigated. The obtained results showed that bioreactor temperature of 45 °C, humidity of 80%, solid bed depth of 0.5 cm, particle size in the range of 0.335–1 mm, substrate initial moisture content of 80% for the top tray and 70% for the middle tray and supplementary substrate of 8% (v/w) olive oil led to maximum lipase production. Under optimum fermentation conditions after 72‐h incubation, maximum lipase activities for the top, middle and bottom trays were 215.16, 199.36 and 52.64 U gds^?1, respectively.     

Sequential Microwave-Ultrasound-Assisted Extraction for Isolation of Piperine from Black Pepper (<Emphasis Type="Italic">Piper nigrum</Emphasis> L.)

Piperine is the natural bioactive component of black pepper (Piper nigrum L.) with several astounding therapeutic properties. In this study, sequential microwave-ultrasound-assisted extraction approach was used for isolation of piperine from black pepper. The effect of various factors such as extraction solvent, particle size of pepper, solvent to solid ratio, microwave power and time and ultrasound temperature and time on the extraction yield of piperine was considered. The maximum extraction yield was 46.6 mg piperine/g pepper which was obtained using ethanol as solvent at the particle size of 0.15 mm, solvent to solid ratio of 20:1, microwave power of 100 W for 1 min, and ultrasound temperature of 50 ^° C for 30 min. This extraction yield was higher than those obtained by Soxhlet (39.1 mg/g), microwave-assisted (38.8 mg/g) and ultrasound-assisted (37.0 mg/g) extractions. The purity of the extracted piperine was 81.4% as determined by HPLC analysis. The FTIR and UV-vis analyses confirmed that the structure of piperine remained intact after extraction and purification which is very important for medicinal applications.     

Exopolysaccharide from Pantoea sp. BCCS 001 GH isolated from nectarine fruit: production in submerged culture and preliminary physicochemical characterizations

Food Science and Biotechnology - Exopolysaccharide (EPS), as potential microbial base polysaccharide source, has plenty of applications due to its unique physicochemical structure. A Pantoea sp....     

Polyaniline grafted chitosan/GO-CNT/Fe3O4 nanocomposite as a superior electrode material for supercapacitor application

Developing appropriate stable electroactive electrode materials for supercapacitor application is the challenging issue, which attracts enormous attention in recent decades. In this regard, Fe₃O₄ nanoparticles are firstly synthesized on chitosan/graphene oxide-multiwall carbon nanotubes (CS/GM/Fe₃O₄). Then, polyaniline (PANI) is grafted on it via in situ chemical polymerization and named as CS/GM/Fe₃O₄/PANI. The as-prepared nanocomposites are characterized by Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The capacitive properties of the electrodes are investigated in a three electrode configuration in 0.5 M Na₂SO₄ electrolyte by various electrochemical techniques. The specific capacitance of CS/GM/Fe₃O₄/PANI electrode is 1513.4 Fg⁻¹ at 4 Ag⁻¹ which is 1.9 times higher than that of CS/GM/Fe₃O₄ (800 Fg⁻¹). Meanwhile, the electrodes exhibit appropriate cycle life along with 99.8% and 93.95% specific capacitance at 100 Ag⁻¹ for chitosan/GO-CNT/Fe₃O₄ and polyaniline grafted chitosan/GO-CNT/Fe₃O₄, respectively.     

Hyperelastic model analysis of stress‐strain behavior in polybutadiene/ethylene‐propylene diene terpolymer nanocomposites

Micromechanics of elastomer nanocomposite samples based on polybutadiene (BR), ethylene‐propylene diene terpolymer (EPDM) hyperelastic matrixes prepared via melt compounding was investigated using uniaxial tensile analysis. Constitutive hyperelastic models, including Polynomial, Yeoh, Ogden, Arruda‐Boyce, and Van der Waals were used to determine material parameters in incompressible isotropic elastic strain‐energy functions on the basis of a nonlinear least squares optimization method by fitting the data obtained from uniaxial classic experiments. Effect of nanoclay (0, 3, 5, 7, and 10 phr) content on the simulation accuracy was investigated. Simulation results compared with the experimental data suggested that the Ogden model as the most consistent model investigated here. J. VINYL ADDIT. TECHNOL., 23:21–27, 2017. © 2015 Society of Plastics Engineers     

An efficient and controllable ultrasonic-assisted microwave route for flower-like Ta(V)–MOF nanostructures: preparation,fractional factorial design,DFT calculations,and high-performance N<Subscript>2</Subscript> adsorption

With respect to different applications of metal–organic framework (MOF) in the medical, industrial and environmental fields, it is very important to choose a new structure that can be synthesized by fast, eco-friendly and affordable methods with distinctive properties so that the properties could be systematically controlled. In this study, new Ta–MOF nanostructures are synthesized by novel methods of microwave (Mw) and ultrasonic assisted microwave (UAMw) in environmental conditions. The final products are characterized by relevant techniques. Although in the both methods, the synthesized products have favourable properties; the use of the UAMw method would produce samples with distinct features such as high thermal stability of 240 °C, average particle size distribution (PSD) of 23 nm and significant specific surface area (SSA) of 2012 m²/g. For a better comprehension of the Ta–MOF formation, computational studies are performed using DFT calculations. In order to investigate the effect of the synthesis parameters on different features of the products, the fractional factorial design is used. The results of analysis of variance confirm that the parameters such as Mw power, Mw duration, ultrasonic temperature, ultrasonic power and ultrasonic duration have a significant effect on PSD and SSA of Ta–MOF samples. Due to the fractional factorial design of the experiments, response surface methodology would optimize the probability of producing samples with the small PSD of 15 nm and high SSA of 2588 m²/g; this desirable amount would provide situations to use these compounds in diverse fields.     

Mathematical models for preemptive shop scheduling problems

More than half a century has passed since Bowman and Dantzig (1959) [13] and [14] introduced their models for preemptive shop scheduling problems. A more efficient model seems to be needed to address all the aspects involved in the problem. We introduce a new Integer Linear Programming (ILP) formulation as a new method for solving the preemptive Job Shop Scheduling Problem (pJSSP). The dimension of the new model, unlike those of the existing ones, depends solely on the number of jobs and machines irrespective of processing times. The proposed model is used as an optimal, two-phase approach. In phase one, the model is solved to obtain the start and completion times of each operation on each machine. In phase two, a simple algorithm in O(mn log n) steps is used to turn these times into a complete and optimal schedule. Different preemptive flow shop problems are studied as special cases of the pJSSP while some related properties are also discussed. Finally, the higher efficiency of the proposed model is verified both theoretically and computationally through its comparison with conventional methods commonly in use.     

Two-sided assembly line balancing considering the relationships between tasks

Previous studies of the two-sided assembly line balancing problem assumed equal relationships between each two tasks assignable to a side of the line. In practice, however, this relationship may be related to such factors as the distance between the implementation place and the tools required for implementation. We know that the more relationships exist between the tasks assigned to each station, the more efficient will be the assembly line. In this paper, we suggest an index for calculating the value of the relationship between each two tasks, and define a performance criterion called ‘assembly line tasks consistency’ for calculating the average relationship between the tasks assigned to the stations of each solution. We propose a simulated annealing algorithm for solving the two-sided assembly line balancing problem considering the three performance criteria of number of stations, number of mated-stations, and assembly line tasks consistency. Also, the simulated annealing algorithm is modified for solving the two-sided assembly line balancing problem without considering the relationships between tasks. This modification finds five new best solutions for the number of stations performance criterion and ten new best solutions for the number of mated-stations performance criterion for benchmark instances.     

Chaotic Behavior of Industrial Fluidized‐Bed Reactors for Polyethylene Production

Recent theories of bifurcation and chaos are used to analyze the dynamic behavior of the UNIPOL process for the production of polyethylene in the gas phase using the Ziegler‐Natta catalyst. Dynamic behavior covers wide regions of the design and operating parameters domain of this industrially important unit. A conventional proportional‐integral (PI) controller was implemented to stabilize the desired operating point on the unstable steady‐state branch. The presence of the PI controller stabilized the desired unstable steady‐state regions to a certain range of catalyst injection rate, by contrast, it is found out that the controlled process can go through a period doubling sequence leading to chaotic strange attractors. The practical implications of this analysis can be very serious, since chaos is shown to exist right near the desired operating point where high polyethylene production rates can be achieved