Preparation and characterization of novel optically active poly(amide‐imide)/α‐Fe2O3 nanocomposites containing l‐alanine moieties

An optically active poly(amide‐imide) (PAI) was synthesized from the polymerization reaction of N,N′‐(Pyromellitoyl)‐bis‐l ‐alanine diacid chloride with 2,5‐diaminotoluene. The obtained inorganic metal oxide nanocomposites composed of PAI/nanostructured hematite (α‐Fe₂O₃) were synthesized through ultrasonic irradiation. The resulting nanocomposites were characterized by Fourier transform infrared spectroscopy, powder X‐ray diffraction, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TEM results indicated that the nanoparticles were dispersed homogeneously in PAI matrix on nanoscale. TGA confirmed that the heat stability of the nanocomposites was improved in the presence of α‐Fe₂O₃ nanoparticles. POLYM. COMPOS., 37:1805–1811, 2016. © 2014 Society of Plastics Engineers     

DG allocation with application of dynamic programming for loss reduction and reliability improvement

Distribution system companies intend to supply electricity to its customers in an economical and reliable manner whereas customers in most distribution system are outspread and connect to distribution system with different type of equipments. These equipment usually have various types and resistance together, that produce highest loss and lowest reliability for distribution systems and customers that are not appreciated in networks. Distributed generations (DGs) are one of the best reliable solutions for these problems if they are allocated appropriately in the distribution system. This paper presents multi-objective function to determine the optimal locations to place DGs in distribution system to minimize power loss of the system and enhance reliability improvement and voltage profile. Time varying load is applied in this optimization to reach pragmatic results meanwhile all of the study and their requirement are based on cost/benefit forms. Finally to solve this multi-objective problem a novel approach based on dynamic programming is used. The proposed methodology is successfully applied to a study case and simulation results are reported to verify the proposed approach.     

Nonlinear membrane model for large amplitude vibration of single layer graphene sheets

The nonlinear vibrational properties of single layer graphene sheets (SLGSs) are investigated using a membrane model. The nonlinear equation of motion is considered for the SLGSs by including the effects of stretching due to large amplitudes. The equation of motion is numerically solved utilizing the finite difference method for SLGSs with different initial and boundary conditions, sizes and pretensions. It is concluded that the nonlinear fundamental frequency of SLGSs increases by increasing the pretension and initial velocity. In addition, it is observed that an increase in the pretension weakens the effects of the initial velocity on the fundamental frequency, such that the fundamental frequency approximately becomes independent of the initial velocity. This is an important feature of the vibrating systems consisting of SLGSs which are used in the nano-electromechanical systems (NEMS), where resonators with a specific fundamental frequency and independent of the initial velocity are of interest.     

Effects of turmeric, shallot extracts, and their combination on quality characteristics of vacuum-packaged rainbow trout stored at 4 ± 1 °C

The effects of turmeric extract (T), shallot extract (Sh), and their combination (T + Sh) on the quality of vacuum-packaged rainbow trout (Oncorhynchus mykiss) were examined during refrigerated storage (4 ± 1 °C) over a period of 20 d. Fish samples were divided into 4 batches; 3 batches were treated by dipping for 30 min in aqueous solution of turmeric extract (1.5%; v/v), shallot extract (1.5%; v/v), or turmeric and shallot extract combination (1.5%+ 1.5% v/v), while the fourth batch was dipped in distilled water as a control sample. The control and the treated fish samples were analyzed periodically for microbiological (total viable count, psychrotrophic count), chemical (total volatile base nitrogen [TVB-N], peroxide value [PV], and thiobarbituric acid [TBA] value), and sensory characteristics. The results indicated that the effect of the T, Sh, and T + Sh on the fish samples were to enable the good quality characteristics to be retained longer and to extend the shelf life during the refrigerated storage.     

Substrate-enhanced microbial fuel cells for improved remote power generation from sediment-based systems

A sediment microbial fuel cell (MFC) produces electricity through the bacterial oxidation of organic matter contained in the sediment. The power density is limited, however, due in part to the low organic matter content of most marine sediments. To increase power generation from these devices, particulate substrates were added to the anode compartment. Three materials were tested: two commercially available chitin products differing in particle size and biodegradability (Chitin 20 and Chitin 80) and cellulose powder. Maximum power densities using chitin in this substrate-enhanced sediment MFC (SEM) were 76 +/- 25 and 84 +/- 10 mW/m2 (normalized to cathode projected surface area) for Chitin 20 and Chitin 80, respectively, versus less than 2 mW/m2 for an unamended control. Power generation over a 10 day period averaged 64 +/- 27 mW/ m2 (Chitin 20) and 76 +/- 15 mW/m2 (Chitin 80). With cellulose, a similar maximum power was initially generated (83 +/- 3 mW/m2), but power rapidly decreased after only 20 h. Maximum power densities over the next 5 days varied substantially among replicate cellulose-fed reactors, ranging from 29 +/- 12 to 62 +/- 23 mW/m2. These results suggest a new approach to power generation in remote areas based on the use of particulate substrates. While the longevity of the SEM was relatively short in these studies, it is possible to increase operation times by controlling particle size, mass, and type of material needed to achieve desired power levels that could theoretically be sustained over periods of years or even decades.     

Self-assembled micelles of well-defined pentaerythritol-centered amphiphilic A4B8 star-block copolymers based on PCL and PEG for hydrophobic drug delivery

Biodegradable star-shaped poly(?-caprolactone) (PCL) with four arms were synthesized by ring-opening polymerization (ROP) from a symmetric pentaerythritol core via the ‘‘core-first’’ strategy. Subsequently, two samples of the amphiphilic A₄B₈ star-block copolymers with symmetrical topologies [4s(PCL-b-2sPEG)] were synthesized by a macromolecular coupling reaction between carboxyl-terminated poly(ethylene glycol) (PEG) and 4-arm star-shaped PCL macromers with eight -OH end groups. The latter was prepared by attaching 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid (HHMPA) to 4sPCL using a simple two-step reaction sequence. The in vitro cytotoxicity test indicated no apparent cytotoxicity. The amphiphilic star-block copolymers are capable of self-assembling into spherical micelles in water at room temperature, and they possess low critical micelle concentrations (CMCs) of 2∼8 mg/L in aqueous solution which was determined by fluorescence spectroscopy using pyrene as a probe. Transmission electron microscopy (TEM) measurement demonstrated that the micelles exhibit a spherical shape with a size range of 30∼50 nm in diameter. In addition, the hydrophobic and anticancer drug, quercetin, is loaded effectively in the polymeric micelles, suggesting that these new materials are appropriate candidates as hydrophobic drug nanocarriers.     

In situ generation of the surface‐modified silica nanoparticles within the silicone matrix

In this study, silica nanoparticles were generated and simultaneously modified inside the silicone resin. Intensive dispersion of the filler and prevention of the cure inhibition effect associated with the regular and unmodified silica particles as well as providing the conditions for grafting to the resin chains were targeted in this work. The dimensions of the nanoparticles, surface morphology, and cure property of the composites were investigated by transmission electron microscopy and differential scanning calorimetry and optimized. Surface chemistry of the modified nanoparticles was investigated by Fourier transform infrared spectroscopy and water contact angle measurement. The effect of in situ synthesis/modification of the silica nanoparticles on mechanical characteristics of the obtained nanocomposites were also examined mainly by tensile properties. POLYM. COMPOS., 36:1365–1370, 2015. © 2014 Society of Plastics Engineers     

Nonlinear dynamic response of tall buildings considering structure–soil–structure effects

Numerous studies have shown that the interaction between adjacent buildings can result in changes in nonlinear dynamic response of structures, damage, and performance level, depending on the dynamic specifications of structures involved and the frequency content of the input motion. To study these effects, finite element method is used for the analytical investigations, and total soil–foundation–structure system is modeled all together. For modeling purposes and in order to realize the effects of the adjacent buildings on the dynamic response, two buildings, namely, 15‐story and 30‐story tall buildings, which were separated by distances of 1/4 and 1/8 of the width of the foundation and were located on hard and soft soil profiles, were considered. It was concluded that in the case where the soil and structure's periods were near to each other, the interaction of adjacent structures on increasing nonlinear responses (displacement and interstory drift) and structural damage indexes was noticeable and therefore was not negligible. Whereas in the case where periods are distant from each other, the interaction of adjacent buildings has a decreasing effect on damage indexes and nonlinear responses and therefore was negligible. Copyright © 2011 John Wiley & Sons, Ltd.     

Pedestrian preferences with respect to roundabouts—A video-based stated preference survey

Research on user behavior and preferences has been a helpful tool in improving road safety and accident prevention in recent years. At the same time, there remain some important areas of road safety and accident prevention for which user preferences, despite their importance, have not been explored. Most road safety research has not explicitly addressed vulnerable user (pedestrians and cyclists) preferences with respect to roundabouts, despite their increasing construction around the world. The present research stems from the fact that studies related to roundabout safety have generally focused on drivers, while overlooking the importance of safety as it relates to vulnerable users, especially pedestrians. Moreover, it handles this particular issue through an approach that has not been used so far in this context; the Stated Preference (SP) survey. As such, there are two main goals (and contributions) of this work. First, to show how SP surveys can be used to investigate the importance of different design and operational features to pedestrian perceptions of safety in roundabouts. This allows us, for example, to quantify how some features of roundabouts (e.g. high traffic volume) can be compensated for by design features such as pedestrian islands. This is useful in helping to design roundabouts that pedestrians prefer and will hopefully use, to help encourage active transport. Second, to demonstrate how traffic simulation software can be successfully used to include difficult-to-communicate attributes in SP surveys.     

Prediction of the heat transfer rate of a single layer wire-on-tube type heat exchanger using ANFIS

In this paper, we applied an Adaptive Neuro-Fuzzy Inference System (ANFIS) model for prediction of the heat transfer rate of the wire-on-tube type heat exchanger. Limited experimental data was used for training and testing ANFIS configuration with the help of hybrid learning algorithm consisting of backpropagation and least-squares estimation. The predicted values are found to be in good agreement with the actual values from the experiments with mean relative error less than 2.55%. Also, we compared the proposed ANFIS model to an ANN approach. Results show that the ANFIS model has more accuracy in comparison to ANN approach. Therefore, we can use ANFIS model to predict the performances of thermal systems in engineering applications, such as modeling heat exchangers for heat transfer analysis.