Dynamically vulcanized polypropylene/ethylene‐propylene diene monomer/organoclay nanocomposites: Effect of mixing sequence on structural,rheological, and mechanical properties

Dynamically vulcanized thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP), ethylene‐propylene diene monomer (EPDM) and cloisite 15A were prepared via direct melt mixing in a co‐rotating twin‐screw extruder. The mixing process was carried out with optimized processing parameters (barrel temperature = 180°C; screw speed = 150 rpm; and feeding rate = 0.2 kg/hr). The formulation used to prepare the nanocomposites was fixed to 75/20/5 (PP/EPDM/Cloisite^©15A), expressed in mass fraction. Effect of mixing sequence on the properties of vulcanized and unvulcanized (TPE) nanocomposites prepared under similar conditions was investigated using X‐ray diffraction (XRD) and a tensile testing machine. Results showed that the sequence of mixing does affect the properties of final TPE nanocomposites. Accordingly, nanocomposite samples prepared through mixing the preblended PP/clay masterbatch with EPDM phase, show better clay dispersion within the polymer matrix. J. VINYL ADDIT. TECHNOL., 22:320–325, 2016. © 2014 Society of Plastics Engineers     

Air-breathing microbial fuel cell with enhanced performance using nanocomposite proton exchange membranes

This work aims to improve the performance of air-breathing microbial fuel cells (MFCs) through using hydrocarbon polymer based nanocomposite proton exchange membranes. Accordingly, nanocomposite membranes based on sulfonated poly(ether ether ketone) (SPEEK) and montmorillonite (MMT) were investigated for such an application. Although the incorporation of MMT into SPEEK membranes resulted in reduced oxygen permeability as well as proton conductivity, but the overall selectivity was found to be improved. MFC tests revealed that using the optimized nanocomposite membrane (SPEEK-70/MMT-3 wt%) results in a considerably higher open circuit voltage (OCV) compared to the corresponding neat membrane. Moreover, it was found that the SPEEK-70/MMT-3 wt% membrane is able to provide about 40% more power output than Nafion^®117. On the account of high proton conductivity, low oxygen permeability, high electrochemical performance, ease of preparation and low cost, hydrocarbon based nanocomposite PEMs could be considered as promising electrolytes to enhance the performance of MFCs.     

Nanocomposites of sodium alginate biopolymer and CdTe/ZnS quantum dots for fluorescent determination of amantadine

A type of novel nanocomposite was successfully synthesized by embedding glutathione capped CdTe/ZnS QDs into sodium alginate biopolymer. The prepared nanocomposite was characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR), fluorescence, and UV–vis spectroscopy. When the obtained nanocomposite interacted with amantadine, its fluorescence intensity was effectively quenched. Under the optimized conditions, the as-prepared nanocomposite provided an efficient platform for detection of amantadine drug within a linear range of 3.1–27.9 × 10^?6 mol/L with a detection limit of 0.09 × 10^?6 mol/L. Because of the satisfactory results for amantadine determination in real samples, it is confirmed that the synthesized nanocomposite is attractive and reliable for use in biological detection and related fields.     

Dissolution-Seepage Coupled Analysis through Formations Containing Soluble Materials

Seepage flow can dissolve particulate soluble materials contained in soil layers and rock formations. The above-mentioned dissolution increases the porosity of the formation and hence seepage flow, which in turn progressively increases the dissolution rate. Due to progressive dissolution, several dams around the world have lost functionality or even failed. Dissolution propagation can be modeled as progress of a solution front, with its progression and resulting excess seepage coupled in the analysis. This is made possible in this paper by simultaneously solving the governing differential equation of seepage and the equation expressing progress of the solution front. The outcome (coupled differential equation) is nonlinear and transient, since both porosity and coefficient of permeability vary with the advancement of the solution front through the medium. The finite-element method is used to solve the resulting nonlinear partial differential equation. Using several examples, influence of material properties and geometry characteristics on the solution front progress and the resulting excess seepage loss is evaluated. Furthermore, effectiveness of different countermeasures (e.g., positive cutoffs and their positions) in dam foundations are studied. Contaminant transport can also be easily modeled and analyzed after applying some modifications into the approach.     

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.     

Temperature Control of a Bench‐Scale Batch Polymerization Reactor for Polystyrene Production

Batch polymerization reactors commonly use optimal temperature control as the strategic operation parameter. This strategy allows for better operability and a more economic process. The main objective of the batch polymerization reactor control is to obtain acceptable product quality. Direct measurement of polymer quality is rarely achievable, which makes the online control of the reactor difficult. Temperature is the most controllable operational variable in the polymer reactor, which is seen to have a direct effect on the polymer properties. Temperature is chosen as the set point by using either the isothermal temperature or optimal temperature trajectory. Online control of the optimal temperature profile of a bench‐scale batch polymerization reactor was experimentally investigated in this study. The temperature trajectory was used as the target for controllers to follow. The time‐profile temperature was obtained with the objective of obtaining the desired conversion and number‐average chain length within the minimum time. Two advanced controls of fuzzy logic control and generic model control were applied to the polymer reactor. A comparison of the controllers reveals that both performed better than conventional controllers.     

MELODY: A completely decentralized adaptive file system for handling real-time tasks in unpredictable environments

We describe the major features of the completely decentralized adaptive file system MELODY which was designed for realizing anintegrated system design for a distributed real-time system working in a hazardous and unpredictable environment. MELODY's adaptivity mechanisms are based on novel services rendered by the distributed operating system DRAGON SLAYER. The file system, in order to both meet real-time constraints and provide for high availability, allows for replicating, relocating, or deleting file copies. Such copies may also bepublic orprivate. At every site aLocal Task Scheduler tries to schedule the arriving critical tasks, based on the availability of resources at this site such that deadline failures are minimized. Depending on the deadline failure history, status changes as well as file replication, deletion, or relocation are analyzed and managed by the cooperatingLocal File Assigners. In order to analyze MELODY's real-time performance we report on simulation experiments in which its capability of minimizing deadline failures of time-critical tasks was compared to other file system models: an idealbest-case model, abaseline model with no file replication, a file system allowingonly for replication ofprivate copies, and a model which allows forreplication and relocation of public copies only. While the best-case is unrealistic for a distributed implementation, the other models embody only part of MELODY's mechanisms yet have the benefit of a considerably smaller communication overhead. We report on the distributed simulation results which unambiguously show MELODY's superior performance, in addition to the built-in sensitivity to changes in the environment. A DRAGON SLAYER/MELODY prototype has been completed in our labs in order to serve as a distributed real-time testbed in our future work with MELODY.This work was partially supported by IBM Endicott (research Agreement No. 6073-86) by the State of Michigan (IMR-87-146751), and by General Dynamics Land Systems (#DEY-605089).     

Supertough (Polyamide 6)/(acrylonitrile butadiene rubber) nano alloy through in situ polymerization of caprolactam in the presence of acrylonitrile butadiene rubber nanophase

In this work, polymerization of caprolactam (CL) was carried out in the presence of acrylonitrile butadiene rubber (NBR) during the reactive melt‐mixing process. During shear mixing, NBR particles swelled and dissolved in the molten CL, which led to separation and distribution of rubber particles to nanoscale in the dissolution stage. Then, in an internal mixer, supertough Polyamide 6 was prepared via melt polymerization of CL/NBR mixture, sodium caprolactam as a catalyst, and hexamethylene diisocyanate as an activator. The effects of various concentrations of catalyst and activator on the initiation time of the reaction were determined. Physical and mechanical properties of different formulations prepared via reactive melt blending were determined by tensile and impact measurements, differential scanning calorimetry, Fourier‐transform infrared spectroscopy, X‐ray scattering techniques, transmission electron microscopy, and dynamic mechanical thermal analysis. Experimental results showed that a recipe with 3% nitrile rubber in a CL/NBR mixture enhances the physical and mechanical properties the best, compared with other formulations. This condition led to the formation of NBR nanospheres during melt polymerization of Polyamide 6 as well. J. VINYL ADDIT. TECHNOL., 21:116–121, 2015. © 2014 Society of Plastics Engineers     

A comparative study on different concentration methods of extracts obtained from two raspberries (Rubus idaeus L.) cultivars: evaluation of anthocyanins and phenolics contents and antioxidant activity

The effects of conventional (CV) and microwave (MW) heating on total soluble solid (TSS) content, total anthocyanin content (TAC), total phenolic content (TPC) and antioxidant activity of raspberry juice obtained from two cultivars of Amol (AM) and Siyahkal (SK) were scrutinised. Antioxidant activity of the juices was measured by 2,2 diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging capacity and expressed as EC₅₀ value. In the both methods, the concentration rate constant for the juices was significantly decreased by increasing operational pressure from 12 to 100 kPa (P < 0.05). A first‐order reaction kinetic model was successfully fitted for the degradation of monomeric anthocyanins at all operating pressures. The results also showed that thermal treatment of MW compared CV in both SK and AM cultivars caused a lower decrease in the TAC, TPC and antioxidant activity. Moreover, the changes in trend of the antioxidant activities due to the thermal treatment were positively correlated with the TPC (r = 0.74, P < 0.05) and TAC (r = 0.61, P < 0.05).     

Study of payment scheduling problem to achieve client–contractor agreement

This paper aims to determine simultaneously the amount, timing, and location of progress payments in projects in order to achieve a set of equitable solutions in the client–contractor negotiation process. The objective function tries to minimize the distance between the final solutions and the best achievable solutions of the client and the contractor. Due to combinatorial nature of the proposed problem, an iterative two-stage search method is proposed. In the first stage, a set of payments is determined to maximize the contractor's net present value (NPV), another set to maximize the client's NPV, and another one to minimize the objective function. In the second stage, activities are rescheduled to improve the solutions by fixing the amount and location of progress payments. A hybrid meta-heuristic algorithm named GASA, along with a simulated annealing (SA) and a genetic algorithm (GA), is introduced for the first stage, while the activities are optimally scheduled in the second stage. It has been shown that SA is better for the contractor’s objective function and GA for the client’s objective function, but GASA is the best in all situations; besides, the proposed method has represented to be an efficient approach to obtain non-dominated solutions in the client–contractor negotiation process.