Processable Thermally Conductive Polyurethane Composite Fibers

The demand for wearable electronics has resulted in an increasing interest in the development of functional fibers, with a specific focus upon the development of electrically conductive fibers incorporable into garments. However, the production of thermally conductive fibers for heat dissipation has been largely neglected. Owing to the very rapid development of miniaturized wearable electronics, there is an increasing need for the development of thermally conductive fibers as heat sinks and thermal management processes. In this study, thermally conductive but electrically insulating boron nitride nanopowder (BNNP) fillers are used to effectively enhance the thermal conductivity and mechanical properties of elastomeric polyurethane fibers. Thermal conductivity enhancement of more than 160% is achieved at very low loadings of BNNP (less than 5 wt%) with an improvement in the mechanical properties of the unmodified fiber. These thermally conductive fibers are also incorporated into 3D textile structures as a proof of processability.     

Orientation-Dependent Host–Dopant Interactions for Manipulating Charge Transport in Conjugated Polymers

Molecular orientation plays a critical role in controlling carrier transport in organic semiconductors (OSCs). However, this aspect has not been explored for surface doping of OSC thin films. The challenge lies in lack of methods to precisely modulate relative molecular orientation between the dopant and the OSC host. Here, the impact of molecular orientation on dopant–host electronic interactions by large modulation of conjugated polymer orientation via solution coating is reported. Combining synchrotron-radiation X-ray measurements with spectroscopic and electrical characterizations, a quantitative correlation between doping-enhanced charge carrier mobility and the Herman's orientation parameter is presented. This direct correlation can be attributed to enhanced charge-transfer interactions at host/dopant interface with increasing face-on orientation of the polymer. These results demonstrate that the surface doping effect can be fundamentally manipulated by controlling the molecular orientation of the OSC layer, enabling optimization of carrier transport.     

Synthesis of carbon nanotube,graphene, CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript>, and NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript> polypyrrole nanocomposites and study their microwave absorption

In this experimental work, different conductive polymer nanocomposites were synthesized using polypyrrole as conductive polymer and CoFe₂O₄, NiFe₂O₄, CNT and graphene as fillers. X-ray diffraction pattern was used to study the crystallinity of the products and it was found CoFe₂O₄, NiFe₂O₄, CNT, and graphene were successfully embedded in the polymer matrix. To further approve the synthesis of the nanocomposites, energy dispersive X-ray spectroscopy was served. Surface groups of the synthesized nanocomposites were studied by Fourier transform infrared and Raman spectroscopy. The morphology of the products was examined by scanning electron microscopy and transmission electron microscopy. It was found the fillers were successfully embedded in the polymer matrix and they were in nanometer scales. To investigate the magnetic properties and conductivity of the polymer nanocomposites, alternating gradient force magnetometer and four-point probe were used, respectively. Finally, the microwave absorption properties of the polymer nanocomposites were studied and it was found the fillers have different effects on the polymer microwave absorption value.     

Performance Evaluation of Deteriorating Highway Bridges Located in High Seismic Areas

This paper studies the life-cycle performance and cost of reinforced concrete highway bridges subjected to earthquake ground motions while they are continuously exposed to the attack of chloride ions. The penetration of chloride ions into the concrete is simulated through a finite difference approach that takes into account all the parameters that can affect the corrosion process. From simulation results, the corrosion initiation time is predicted, and the extent of structural degradation is calculated over the entire life of the bridge. A group of detailed bridge models with various structural attributes are developed to evaluate the changes in the structural capacity and seismic response of corroded bridges. For the purpose of the probabilistic seismic risk assessment of bridges, the seismic fragility curves are generated and updated at regular time intervals. The time-dependent fragility parameters are employed to investigate the life-cycle cost of bridges by introducing a performance index that combines the effects of probable seismic events and chloride-induced corrosion. The proposed approach provides a multihazard framework that leads to more realistic performance and cost estimates.     

Biochemical studies on some non conventional sources of protein Part 1. Tomato seeds and peels

Tomato seeds and skin wastes contain considerable amounts of protein (16.6, 5.7%) respectively. After protein hydrolysis from both seeds and peels the presence of 17 amino acids was stated. The amino acid scores (chemical scores) of tomato pomace were calculated using the FAO/WHO provisional amino acid scoring pattern and reasonable biological value was confirmed. The essential amino acid content and biological value of seed proteins are higher than that of skin proteins. Fe, Zn, Cu and Mn in seeds and peels were predominant among the micro-minerals. K and P were found to be present in greater quantities than Na in seeds and peels.     

Transglutaminase-mediated incorporation of whey protein as fat replacer into the formulation of reduced-fat Iranian white cheese: physicochemical,rheological and microstructural characterization

The effects of transglutaminase treatment (0–2 units/g milk protein) on the chemical composition, textural characteristics, proteolysis and yield of reduced-fat Iranian white cheese (milk fat: 0.4–1.4% w/w) incorporated with whey proteins (0–6 g/L milk) were investigated. Enzyme-mediated inclusion of whey proteins in the reduced-fat cheese caused a noticeable increase in moisture to protein (M:P) ratio with concomitant decease in the hardness rheological parameters of fracture stress and Young’s and storage (G’) moduli. However, increase in concentrations of whey proteins or/and transglutaminase enzyme above a critical level led to formation of a cheese matrix with lower moisture content and greater values of hardness indices. Whey protein addition and transglutaminase treatment resulted in the same trends of changes in proteolysis rate and cheese yield as in cheese softness. Response surface method (RSM) suggested that the enzymatic incorporation of 4.2 g deliberately added whey proteins to 1 L of milk (1.04% w/w fat) into the cheese matrix using 0.833 unit transglutaminase per gram milk protein would provide a reduced-fat product with the softest texture and the highest yield. The scanning electron micrographs showed formation of honeycomb structures in the protein matrix of the reduced-fat sample with optimum formulation.     

The effects of human menstrual blood stem cells‐derived granulosa cells on ovarian follicle formation in a rat model of premature ovarian failure

Many studies have reported that human endometrial mesenchymal stem cells (HuMenSCs) are capable of repairing damaged tissues. The aim of the present study was to investigate the effects of HuMenSCs transplantation as a treatment modality in premature ovarian failure (POF) associated with chemotherapy‐induced ovarian damage. HuMenSCs were isolated from menstrual blood samples of five women. After the in vitro culture of HuMenSCs, purity of the cells was assessed by cytometry using CD44, CD90, CD34, and CD45 FITC conjugate antibody. Twenty‐four female Wistar rats were randomly divided into four groups: negative control, positive control, sham, and treatment groups. The rat models of POF used in our study were established by injecting busulfan intraperitoneally into the rats during the first estrus cycle. HuMenSCs were transplanted by injection via the tail vein into the POF‐induced rats. Four weeks after POF induction, ovaries were collected and the levels of Amh, Fst, and Fshr expression in the granulosa cell (GC) layer, as well as plasma estradiol (E2) and progesterone (P4) levels were evaluated. Moreover, migration and localization of DiI‐labeled HuMenSCs were detected, and the labeled cells were found to be localized in GCs layer of immature follicles. In addition to DiI‐labelled HuMenSCs tracking, increased levels of expression of Amh and Fshr and Fst, and the high plasma levels of E2 and P4 confirmed that HuMenSC transplantation had a significant effect on follicle formation and ovulation in the treatment group compared with the negative control (POF) group.     

Nanofluid thin film flow and heat transfer over an unsteady stretching elastic sheet by LSM

This study is carried out on the unsteady flow and heat transfer of a nanofluid in a stretching flat plate. Least square method is implemented for solving the governing equations. It also attempts to demonstrate the accuracy of the aforementioned method compared with a numerical one, Runge-Kutta fourth order. Furthermore, the impact of some physical parameters like unsteadiness parameter (S), Prandtl number (Pr) and the nanoparticles volume fraction (?) on the temperature and velocity profiles is scrutinized carefully. Accordingly, the results obtained from this study reveal that the temperature enhances by means of augmenting the nanoparticles volume fraction. At η ∈ {0, 0.5}, the velocity decreases as a result of a rise in nanoparticles volume fraction and at η ∈ {0.5, 1}, an opposite treatment takes place. Moreover, velocity distribution augments by raising the S value, however an inverse trend is observed in temperature values. Moreover, the local skin friction coefficient indicated a notable rise by increasing the S parameter as well as a steady decrease by rising ?. Finally, water-Alumina nanofluid demonstrated better heat transfer enhancement compared to other types of nanofluids.     

Simple indoline based donor–acceptor dye for high efficiency dye-sensitized solar cells

A simple metal-free donor–acceptor type sensitizer U01, bearing strong electron donor indoline-triphenylamine was synthesized for panchromatic sensitization of TiO₂ nanocrystalline film. Photovoltaic properties of U01 showed remarkably enhanced light harvesting due to the presence of strong electron donor and robust structure. The new U01 sensitized solar cell exhibited a photovoltaic performance: a short-circuit photocurrent density (J_sc) of 10.70 mA cm⁻², an open-circuit photovoltage (V_oc) of 0.758 V and a fill factor (FF) of 0.74, corresponding to an overall conversion efficiency of 6.01% under standard global AM 1.5 solar light condition. Our results suggest that indoline-triphenylamine based robust D–A molecular architecture is a highly promising class of panchromatic sensitizers for improvement of the performance of dye-sensitized solar cells (DSCs).     

A simplified method for collapse capacity assessment of moment-resisting frame and shear wall structural systems

A simplified methodology for predicting the median and dispersion of collapse capacity of moment-resisting frame and shear wall structural systems subjected to seismic excitations is proposed. The method is based on nonlinear static (pushover) analysis. Simple mathematical models denoted as “generic structures” are utilized to model moment-resisting frames and shear walls. After examining a wide range of structural parameters of the generic structures, a comprehensive database of collapse fragilities and pushover curves (using ASCE 7-05 lateral load pattern) are generated. Based on the obtained pushover curves, closed-form equations for estimation of median and dispersion of building collapse fragility curves are developed using multivariate regression analysis. Comparing the estimates of the median collapse capacity calculated from the closed-form equations with the actual collapse capacities determined from nonlinear response-history analysis indicates that the simplified methodology is reliable. The effectiveness of this methodology for predicting the median collapse capacity of frame and wall structures is further demonstrated with two case studies of structural systems designed based on current seismic provisions.