Processing and Low Voltage Switching of Organic Ferroelectric Phase‐Separated Bistable Diodes

The processing of solution‐based binary blends of the ferroelectric random copolymer poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE) and the semiconducting polymer poly(9,9‐dioctylfluorenyl‐2,7‐diyl) (PFO) applied by spin‐coating and wire‐bar coating is investigated. By systematic variation of blend composition, solvent, and deposition temperature it is shown that much smoother blend films can be obtained than reported thus far. At a low PFO:P(VDF‐TrFE) ratio the blend film consists of disk‐shaped PFO domains embedded in a P(VDF‐TrFE) matrix, while an inverted structure is obtained in case the P(VDF‐TrFE) is the minority component. The microstructure of the phase separated blend films is self‐affine. From this observation and from the domain size distribution it is concluded that the phase separation occurs via spinodal decomposition, irrespectively of blend ratio. This is explained by the strong incompatibility of the two polymers expressed by the binary phase diagram, as constructed from thermal analysis data. Time resolved numerical simulation of the microstructure evolution during de‐mixing qualitatively shows how an elevated deposition temperature has a smoothening effect as a result of the reduction of the repulsion between the blend components. The small roughness allowed the realization of bistable rectifying diodes that switch at low voltages with a yield of 100%. This indicates that memory characteristics can be tailored from the outset while processing parameters can be adjusted according to the phase behavior of the active components.     

A Novel Approach for Environmentally Friendly Production of Single Cell Protein From Petrochemical Wastewater Using a Halophilic Microorganism in Different Conditions

In this study, biodegradation of petrochemical wastewater and production of single cell protein from it as carbon source was investigated using several process parameters. The process parameters such as carbon source, type of phosphorus source, phosphorus source concentration, type of nitrogen source, nitrogen source concentration, and temperature were considered. In order to investigate the influence of process parameters, a factorial design using Taguchi method was applied with six factors at four levels. The optimum medium composition for single cell protein production was found to contain petrochemical wastewater 8%, peptone 0.2%, and K₂HPO₄ 0.008% at temperature 37°C. The percentage ratio of single cell protein to cell dry weight in optimal conditions was 76.4%. In conclusion, Haloarcula sp. IRU1 can degrade petrochemical wastewater and use it as carbon source for single cell protein production in different conditions.     

Effect of gum tragacanth on rheological and physical properties of a flavored milk drink made with date syrup

Date syrup as a nutritional additive and safe alternative to added sugar is one of the best choices for milk flavoring. In this study, a flavored milk beverage was formulated using date syrup for flavoring the product and gum tragacanth to obtain an acceptable mouth feel. Steady shear and dynamic oscillatory rheological properties of the samples contained 3 concentrations (0, 0.1, 0.2, and 0.3%, wt/wt) of 2 types of gum tragacanth (Astragalus gossypinus and Astragalus rahensis) which at 3°C, were studied. Particle size distribution and colorimetric assays were determined by laser diffractometry and using reflection spectrometer, respectively. Sensory analysis was performed with 25 semitrained panelists, using a 5-point hedonic scale. The results showed that viscoelastic properties, flow behavior parameters, particle size, and color parameters (L^*, a^*, and b^*, where L^* represents lightness, a^* represents the redness/greenness quality of the color, and b^* represents the yellowness and blueness quality of the colors) were significantly affected by the concentration of the gum tragacanth and the severity of this effect was influenced by the type of gum. The use of appropriate type and concentration of gum tragacanth in date milk formulation can improve the texture and mouth feel by affecting on particle size and the flow behavior of this product.     

A study on siro,solo, compact,and conventional ring-spun yarns. Part III: modeling fiber migration using modular adaptive neuro-fuzzy inference system

The importance of fiber migration in spun yarns as a means of securing cohesion and strength has been emphasized in the literature. However, analyzing migration behavior of fibers is a time-consuming and tedious task. A three-stage hybrid model was developed to estimate yarn migratory properties based on some physical and mechanical properties of spun yarns. Achieving the objectives of this research, general physical, mechanical, and structural properties of spun yarns together with existing standards were thoroughly studied. At the first stage, using stepwise regression analysis, key variables were selected. At the second stage, data-set was clustered into subpopulations by means of K-means in order to decrease effects of noise, rebate complexity of the patterns, and develop a modular model. At the third stage, using adaptive neuro-fuzzy inference system, the target value was predicted. Finally, evaluation of the proposed model was carried out by applying it on the test set.     

Synthesis and structural characterization of novel bionanocomposite poly(ester-imide)s containing TiO2 nanoparticles, S-valine, and l-tyrosine amino acids moieties

The incorporation of different percents of titanium dioxide (TiO₂) nanoparticles into optically active poly(ester-imide) (PEI), afforded an opportunity to prepare several novel PEI/TiO₂ bionanocomposites (BNC)s. To this point, firstly PEI was synthesized via direct polyesterification of chiral diacid monomer and an optically active phenolic diol using tosyl chloride/pyridine/N,N-dimethylformamide system as a condensing agent. Novel BNC polymers containing TiO₂ nanoparticles were synthesized through ultrasonic irradiation method. With the aim of γ-amidopropyl-triethoxylsilicane as a coupling agent, the surface of nanoscale TiO₂ was modified to decrease aggregation of nanoparticles in polymer matrix. The obtained PEI/TiO₂ BNCs were characterized with FT-IR, thermogravimetric analysis (TGA), scanning electron microscopy, X-ray diffraction, and transmission electron microscopy (TEM) techniques. Consequently, TEM image showed that the nanoparticles of smaller than 50 nm in diameter were uniformly dispersed in the polymer matrix. TGA data demonstrated that new synthesized PEI/TiO₂ BNCs are more thermally stable in compare to pure PEI.     

Simultaneous removal of carbon and nutrients from an industrial estate wastewater in a single up-flow aerobic/anoxic sludge bed (UAASB) bioreactor

Simultaneous removal of carbon and nutrients (CNP) in a single bioreactor is highly significant for energy consumption and control of reactor volume. Basically, nutrients removal is dependant to the ratio of biochemical oxygen demand to chemical oxygen demand (BOD₅/COD). Thus, in this study the treatment of an industrial estate wastewater with low BOD₅/COD ratio in an up-flow aerobic/anoxic sludge bed (UAASB) bioreactor, with an intermittent regime in aeration and discharge, was investigated. Hydraulic retention time (HRT) of 12-36 h and aeration time of 40-60 min/h were selected as the operating variables to analyze, optimize and model the process. In order to analyze the process, 13 dependent parameters as the process responses were studied. From the results, it was found, increasing HRT decreases the CNP removal efficiencies. However, by increasing the BOD₅ fraction of the feed, the total COD (TCOD), slowly biodegradable COD (sbCOD), readily biodegradable COD (rbCOD), total nitrogen (TN), and total phosphorus (TP) removal efficiencies were remarkably increased. Population of heterotrophic, nitrifying and denitrifying bacteria showed good agreement with the results obtained for TCOD and TN removal. The optimum conditions were determined as 12-15 h and 40-60 min/h for HRT and aeration time respectively.     

Effects of muscle fatigue on the ground reaction force and soft-tissue vibrations during running: a model study

A modeling approach is used in this paper to study the effects of fatigue on the ground reaction force (GRF) and the vibrations of the lower extremity soft tissues. A recently developed multiple degrees-of-freedom mass-spring-damper model of the human body during running is used for this purpose. The model is capable of taking the muscle activity into account by using a nonlinear controller that tunes the mechanical properties of the soft-tissue package based on two physiological hypotheses, namely, "constant force" and "constant vibration." In this study, muscle fatigue is implemented in the model as the gradual reduction of the ability of the controller to tune the mechanical properties of the lower body soft-tissue package. Simulations are carried out for various types of footwear in both pre- and postfatigue conditions. The simulation results show that the vibration amplitude of the lower body soft-tissue package may considerably increase (up to 20%) with muscle fatigue, while the effects of fatigue on the GRF are negligible. The results of this modeling study are in line with the experimental studies that found muscle fatigue does not significantly change the GRF peaks, but may increase the level of soft-tissue vibrations (particularly for hard shoes). A major contribution of the current study is the formulation of a hypothesis about how the central nervous system tunes the muscle properties after fatigue.     

Experimental investigation and mathematical modeling of oxygen permeation through dense Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) perovskite-type ceramic membranes

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ (BSCF) perovskite powder was synthesized via EDTA/citrate complexation method. BSCF membranes were formed by pressing powder at 400 MPa and sintering at 1100 °C for 10 h. XRD patterns showed that a high pure powder with cubic structure was obtained. SEM micrographs revealed that the membranes are dense with large grains. Effects of temperature, feed and permeate side oxygen partial pressures, flow rates and membrane thickness on oxygen permeation flux were studied experimentally. A Nernst–Planck based mathematical model, including surface exchange kinetics and bulk diffusion, was developed to predict oxygen permeation flux. Considering non-elementary surface reactions and introducing system hydrodynamics into the model resulted in an excellent agreement (RMSD = 0.0617, AAD = 0.0487 and R² = 0.985) between predicted and measured fluxes. The results showed that oxygen permeation flux increases with temperature, feed side oxygen partial pressure and flow rates, however decreases with permeate side oxygen partial pressure and membrane thickness. Contribution of feed side surface exchange reactions, bulk diffusion and permeate side surface exchange reactions resistances in the total resistance are in the range of 8–32%, 10–81% and 11–59%, respectively. Permeation rate-limiting step was determined using the membrane dimensionless characteristic thickness.     

Tubular composite PVA ceramic supported membrane for bio-ethanol production

Thin polyvinyl alcohol (PVA) layers loaded with fumed silica were coated on porous ceramic supports. Scanning electron microscope (SEM) was used to characterize the ceramic-supported thin PVA active layers and the effects of coating gel PVA concentration on thickness and density of the active layers were investigated. Pervaporation (PV) dehydration of 90 wt.% ethanol was performed at temperatures of 30, 45 and 60 °C. The values of water flux (0.05–2.92 kg/m² h) and selectivity (3–180) exceed typical values obtained for pure PVA membranes. Besides the pervaporation separation index (PSI) varies from 5.84 to 82.81. Compared to pure PVA membrane with maximum PSI of 47.2, the pervaporation performance was significantly improved. The best separation performance was obtained using the membrane prepared from 5 wt.% PVA solution containing 6 wt.% fumed silica and at pervaporation temperature of 45 °C with permeation flux of 1.69 kg/m² h, and selectivity of 50. The highest permeation flux, selectivity and PSI was 2.92 kg/m² h, 180 and 82.81, obtained at 60, 30 and 45 °C, respectively, while using membranes loaded with 8, zero and 6 wt.% of fumed silica in PVA membrane prepared from 5, 10 and 5 wt.% PVA solutions, respectively. The novel ceramic support increased mechanical strength of the membrane and protected the ultrathin polymeric top active layer under aggressive operating conditions, especially high pressure gradient across the membrane. Incorporation of fumed silica also resulted in higher water permeation flux. Due to these results, the synthesized membranes are suitable for ethanol purification in industrial scales.     

Fabrication of Cerium Oxide Nanoparticles by Solution Combustion Synthesis and Their Cytotoxicity Evaluation

The diverse abilities such as the antioxidant effect of cerium oxide nanoparticles (CeO₂-NPs) have encouraged researchers to pursue CeO₂-NPs as a therapeutic agent to treat a number of diseases, including cancer and diabetes. The synthesis method of CeO₂-NPs affected on its abilities. In this study, nanosize ceria powders were synthesized by combustion of aqueous containing corresponding cerium nitrate, ammonium nitrate, and glycine redox mixtures. Solution combustion synthesis is a fast and cost-efficient process with high purity product. The crystallite structures were characterized by various methods, including X-ray diffraction technique, high-resolution scanning electron microscopy, transmission electron microscopy, and UV–vis spectroscopy technique. The combustion was flaming and yields voluminous oxides with nano size (20–30 nm). In addition, no diffraction patterns that are characteristic of impurities were observed, indicating the purity of the CeO₂-NPs. In vitro cytotoxicity studies on L929 cells, a non-toxic effect in all concentration (up to 1000 μg/mL) was indicated and it can be believed that this nanoparticle will have viable applications in different medical fields.