Chemical kinetics simulation of deposition and sp2/sp3 bond ratio of diamond-like carbon film in plasma

In this work a theoretical model for the simulation of diamond-like carbon (DLC) film deposition in thermal plasma will be investigated. A chemical kinetics model for the most important molecular processes occurring in the gas-phase and gas-surface will be presented. This investigation is focused on the molecular processes in the gas and the elementary interactions of activated gas species with the deposited surface. The model quantitatively predicts the kinetics concentration of important plasma activated species. Also the net rate of the production of gas, surface, and bulk phase species will be calculated. Finally the growth rate of DLC film and the sp²/sp³ growth ratio under different reactor conditions (temperature, gas flow rate and reactor pressure) will be calculated and verified with literature data.     

Multi-objective exergy-based optimization of a continuous photobioreactor applied to produce hydrogen using a novel combination of soft computing techniques

This work was aimed at proposing a flexible and reliable framework based on combination of three soft computing techniques, i.e., artificial neural network, genetic algorithm, and fuzzy systems for multi-objective exergetic optimization of continuous photobiohydrogen production process from syngas by Rhodospirillum rubrum bacterium. To this end, artificial neural network (ANN) coupled with fuzzy clustering method (FCM) to model exergetic outputs on the basis of input variables. The outputs of modeling system were then fed into a novel optimization approach developed by hybridizing additive linear interdependent fuzzy multi-objective optimization (ALIFMO) and the elitist non-dominated sorting genetic algorithm (NSGA-II). The optimization was carried out to minimize the normalized exergy destruction and maximize the rational and process exergetic efficiencies, simultaneously. The solutions of the proposed approach were also compared with conventional fuzzy multi-objective optimization procedure with independent objectives. Overall, the modeling system predicted the exergetic parameters of photobioreactor with a coefficient of determination higher than 0.90. Furthermore, the optimization approach suggested syngas flow rate of 13.35 mL/min and agitation speed of 383.34 rpm as the best operational condition by considering the preferences of process exergy efficiency, rational exergy efficiency, and normalized exergy destruction, respectively. This condition could yield the normalized exergy destruction of 1.56, process exergetic efficiency of 21.66%, and rational exergetic efficiency of 85.65%. The obtained results showed the superiority of the proposed approach over the conventional fuzzy method in optimizing the complex biofuel production systems.     

Inventory policies and dynamic pricing under possibility and rivals

Income management has recently become a desirable service in many circumstances. Decision makers recognize that even small developments in their operations can have a notable effect on their benefits. Nonetheless, the specification of pricing and optimal inventory policies in more practical situations may not be a manageable task. Eventually, competitors influence a supplier’s best strategy by affecting their demand, incomes, and other related actions. This paper considers a continual time optimal control model for the learning of a dynamic pricing and inventory control problem in a make-to-stock system. We evaluate a product-capacitated, dynamic setting and present a demand-based model with convex prices. Our results explain the role of capacity and the effects of the dynamic nature of demand. We then propose an additive model of demand uncertainty. We show that the strong formulation is of the same level of complication as the deterministic problem and indicate how to modify the solution method.     

Cu(acac)<Subscript>2</Subscript>–PVA composite nanofibers in catalysis of Michael addition of carbon nucleophiles to α,β-unsaturated carbonyl compounds

Copper (II) acetylacetonate containing nanofibers of polyvinyl alcohol (Cu(acac)₂–PVA) were prepared by electrospinning and characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, inductively coupled plasma (ICP) and diffuse reflectance spectroscopy. The obtained nanofibers were almost uniform and uniaxially aligned with their longitudinal axes oriented randomly and no entanglement was observed between them. It was also found that Cu(acac)₂ was embedded as distinct nanoparticles inside and over the walls of the nanofibers. The obtained nanocomposite was successfully used as a recoverable heterogeneous catalyst in the Michael addition reaction of carbon nucleophiles such as malononitrile, indole and 2-methylindole to various α,β-unsaturated carbonyl compounds. The Michael addition reaction proceeded smoothly at room temperature in dry THF. Under very mild reaction conditions, good to excellent yields of the desired products were obtained. Although one favorable feature of the catalyst was ease of recycling, a minor decrease in its efficiency during successive runs was observed. It was found that 7% decrease in efficiency after four successive runs may be due to the slight leaching of Cu(acac)₂ into the solution based on an ICP analysis of the recovered catalyst of the fourth run.     

Synthesis of poly(ε-caprolactone)-based polyurethane semi-interpenetrating polymer networks as scaffolds for skin tissue regeneration

A new biodegradable poly(ε-caprolactone)-polyurethane semi-interpenetrating polymer network (PCL-PU-semi-IPNs) was synthesized through the reaction of hydroxyl-terminated four-armed star-shaped PCL, 1,4-diisocyanatobutane, and ethylenediamine. Afterwards, the three-dimensional (3D) porous structure of the polymer was prepared through particulate leaching and freeze-drying methods. The chemical structure of star-shaped block PCL-PU polymer was confirmed by ¹H NMR and IR spectroscopy. The morphology of the fabricated PCL-PU-semi IPN scaffolds was identified by scanning electron microscopy. Results indicated that lower polymer concentration can lead to formation of an isolated pore with a small size, while increasing polymer concentration increases the pore size. Fibroblast cells culturing on the scaffold suggests that the fabricated PU-based scaffold is biocompatible and can be considered as a suitable scaffold material for skin tissue engineering applications.     

A high slew-rate unity-gain low-voltage buffer with largeactive/quiescent current ratio

A buffer that can source or sink up to 10 mA with a slew rate of 130 V/μs in a series RC load of 500 Ω and 12 nF is introduced. The buffer has a standby current of 400 μA which is reduced to 50 nA in less than 100 ns in power-down mode. It operates with a 2.7-V supply and is designed for personal communications applications such as Digital Enhanced Cordless Telecommunications (DECT). The adaptive biasing technique employed in this design makes it suitable for other applications like high-speed sample-and-hold or transconductance stages     

Disinfection of dairy wastewater effluent through solar photocatalysis processes

Due to the strict regulations and reuse policies that govern wastewater's use as an irrigation water resource for agricultural purposes, especially in dry climates, optimization of the disinfection process is of the utmost importance. The effects of solar radiation along with Titanium dioxide(TiO_2) nanoparticles applied to optimization of the photolysis and photocatalysis processes for inactivating heterotrophic bacteria were investigated. Temperature, p H, and dissolved oxygen fluctuations in the dairy wastewater effluent treated by activated sludge were examined. In addition,different dosages of TiO_2 were tested in the solar photocatalysis(ph-C S) and concentrated solar photocatalysis(ph-C CS) processes. The results show that the disinfection efficiencies of the solar photolysis(ph-L S) and concentrated solar photolysis(ph-L CS) processes after 30 min were about 10.5% and 68.9%, respectively, and that the ph-C S and ph-C CS processes inactivated 41% and 97% of the heterotrophic bacteria after 30 min, respectively. The p H variation in these processes was negligible. Using the ph-L CS and ph-C CS processes, the synergistic effect between the optical and thermal inactivation caused complete disinfection after three hours. However, disinfection was faster in the ph-C CS process than in the ph-L CS process. Significant correlations were found between the disinfection efficiency and the variation of the dissolved oxygen concentration in the ph-C S and ph-C CS processes, while the correlations between the disinfection efficiency and temperature variation were not significant in the ph-L S and ph-C S processes. Moreover, the oxygen consumption rate was greatest(3.2 mg··L~(-1)) in the ph-C CS process. Hence,it could be concluded that the ph-C CS process is an efficient photocatalysis process for disinfection of dairy wastewater effluent.     

Long-Wave Infrared Thermophotonic Imaging of Demineralization in Dental Hard Tissue

Dental caries remains the most prevalent chronic disease in both children and adults worldwide. To address this prevalence through disease prevention and management, dentists need tools capable of detecting caries at early stages of formation. Looking into the physics of light propagation in teeth, this study presents a clinically and commercially viable platform technology for thermophotonic detection of early dental caries using an inexpensive long-wavelength infrared (LWIR; 8 \(\upmu \)m to 14 \(\upmu \)m) camera. The developed system incorporates intensity-modulated light to generate a thermal-wave field inside enamel and uses the subsequent infrared emission of the thermal-wave field to detect early caries. It was found that the greater light absorption at caries sites shifts the thermal-wave field centroid, providing contrast between early caries and intact enamel. Use of LWIR detection band in dental samples is novel and beneficial over the conventional mid-wavelength infrared band (3 \(\upmu \)m to 5 \(\upmu \)m) as it suppresses the masking effect of the instantaneous radiative emission from subsurface features due to the minimal transmittance of enamel in the LWIR band. The efficacy of the LWIR system is verified though experiments carried out on nonbiological test samples as well as on teeth with natural and artificially induced caries. The results suggest that the developed LWIR technology is an affordable early dental caries detection system suitable for commercialization/translation to Dentistry.