Laser-induced birefringence of methyl red in a polymeric nanocomposite prepared by sol–gel method

Non-linear optical (NLO) dyes used as guests in polymeric films have recently attracted interests in optical applications. In this regard, dye-grafted polymeric systems can outperform conventional guest?Chost dye-containing films because they have lower loading limitations and aggregation problems. These give rise to enhanced molecular orientation. The work presented here is an attempt to study the laser-induced birefringence for a novel sol?Cgel based polymeric nanocomposite prepared by reacting an NLO dye (methyl red) and an epoxy silane coupling agent at different concentrations of dye. 3-Glycidoxy propyltrimethoxysilane was hydrolyzed and condensed to prepare a siloxane structure from which a dye-containing hybrid was obtained. The structural and morphological properties of the resulting nanocomposites were studied by FTIR spectroscopy, differential scanning calorimetry and transmission electron microscopy. Results showed that the dye was chemically attached to the siloxane structure built through sol?Cgel processing. This chemical modification leads to nanostructured morphology in which inorganic phase was entangled to the organic phase. The size of clusters formed was 60?C80?nm in dimension. The optical responses of nanocomposites were investigated at different process parameters, including dye concentration, film thickness and curing regimes. These were then discussed based on the photochemical and photothermal properties of the dye molecules, the rotation dynamic of which was shown to strongly depend on the physical and chemical properties of the host. The samples with 8 wt% of dye revealed the maximum birefringence, while the sample with 10 wt% showed the best memory effect. The best condition for curing was found to be 24?h. By increasing the film thickness, there was an increase in the amount of induced birefringence.     

Experimental investigation of aluminum oxide nanofluid on heat pipe thermal performance

In this research, the effect of using aluminum oxide nanofluid (pure water mixed with Al₂O₃ nanoparticle with 35 nm diameter) on the thermal efficiency enhancement of a heat pipe on the different operating state was investigated.     

Fracture of unsaturated polyester and the limitation of layered silicates

In this work, we explain why the incorporation of organically modified nano‐clay into unsaturated polyester resins, unlike epoxy, does not improve their fracture toughness despite continuing aggressive research activities based on this approach. The mechanism behind this phenomenon is explored by studying the effect of mixing method on improving the degree of exfoliation in simple nanocomposites and its final effect on fracture behaviour. Rheometry and X‐ray diffraction show that the two mixing methods lead to different degrees of exfoliation. The mechanical properties primarily depend on clay content and are less sensitive to degree of exfoliation. In the case of toughness, there is no observable effect of degree of exfoliation. This despite the increased fracture surface area evident in SEM images of the sample with finer exfoliation as compared with those of the sample with a lower degree of exfoliation. Dispersed silicate layers influence the toughness by increasing the tortuosity of the crack path locally while micron scale intercalated tactoids can result in crack deflection. Both of these mechanisms depend on localized plasticity for significant energy dissipation. Since unsaturated polyester has very low localized plasticity below ～90°C, one cannot significantly improve its room temperature toughness by manipulating the micro‐/nanostructure of the nanocomposite the nanocomposite without incorporating another material. This new understanding of the fracture behavior of unsaturated polyesters and their nanocomposites allows for the development of more complex toughened systems. POLYM. ENG. SCI., 55:1303–1309, 2015. © 2015 Society of Plastics Engineers     

Magnetic molecularly imprinted polymer nanoparticles coupled with high performance liquid chromatography for solid‐phase extraction of carvedilol in serum samples

Herein, we report a magnetic molecularly imprinted polymers (m‐MIPs) using Fe₃O₄ as a magnetic component, carvedilol as a template molecule for the solid‐phase extraction (MISPE) as the sample clean‐up technique combined with high‐performance liquid chromatography (HPLC) and for the controlled release of carvedilol at different pH values of 1.0 (simulated gastric fluid), 6.8 (simulated intestinal fluid), and 7.4 (simulated biological fluid). The adsorption kinetics was modeled with the pseudo‐first‐order and pseudo‐second‐order kinetics, and the adsorption isotherms were fitted with Langmuir and Freundlich models. The performance of the m‐MIPs for the controlled release of carvedilol was assessed and results indicated that the magnetic MIPs also have potential applications in controlled drug release. Furthermore, the m‐MIPs were applied to the extraction of carvedilol from human blood plasma samples. Carvedilol can be quantified by this method in the 2–350 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.13 and 0.45 μg L^?1. The results from HPLC showed good precision (3.5% for 50.0 μg L^?1) and recoveries (between 85 and 93) using m‐MIP from human plasma samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41209.     

Impedance control of an active suspension system

A novel control system is developed to control dynamic behavior of a vehicle subject to road disturbances. The novelty of this paper is to apply the impedance control on an active vehicle suspension system operated by a hydraulic actuator. A relation between the passenger comfort and vehicle handling is derived using the impedance parameters. The impedance control law is simple, free of model and can be applied for a broad range of road conditions including a flat road. Impedance control is achieved through two interior loops which are force control of the actuator by feedback linearization and fuzzy control loop to track a desired body displacement provided by the impedance rule. The system stability is analyzed. A quarter-car model of suspension system and a nonlinear model of hydraulic actuator are used to simulate the control system.     

Compartment modeling for mammalian protein turnover studies by stable isotope metabolic labeling

Protein turnover studies on a proteome scale based on metabolic isotopic labeling can provide a systematic understanding of mechanisms for regulation of protein abundances and their transient behaviors. At this time, these large-scale studies typically utilize a simple kinetic model to extract protein dynamic information. Although many high-quality, protein isotope incorporation data are available from those experiments, accurate and additionally useful protein dynamic information cannot be extracted from the experimental data by use of the simple kinetic models. In this paper, we describe a formal connection between data obtained from elemental isotope labeling experiments and the well-known compartment modeling, and we demonstrate that an appropriate application of a compartment model to turnover of proteins from mammalian tissues can indeed lead to a better fitting of the experimental data.     

Large-area vapor-phase growth and characterization of MoS(2) atomic layers on a SiO(2) substrate

Atomic-layered MoS(2) is synthesized directly on SiO(2) substrates by a scalable chemical vapor deposition method. The large-scale synthesis of an atomic-layered semiconductor directly on a dielectric layer paves the way for many facile device fabrication possibilities, expanding the important family of useful mono- or few-layer materials that possess exceptional properties, such as graphene and hexagonal boron nitride (h-BN).     

A Bioinspired Platform for Effective Delivery of Protein Therapeutics to the Central Nervous System

Central nervous system (CNS) diseases are the leading cause of morbidity and mortality; their treatment, however, remains constrained by the blood–brain barrier (BBB) that impedes the access of most therapeutics to the brain. A CNS delivery platform for protein therapeutics, which is achieved by encapsulating the proteins within nanocapsules that contain choline and acetylcholine analogues, is reported herein. Mediated by nicotinic acetylcholine receptors and choline transporters, such nanocapsules can effectively penetrate the BBB and deliver the therapeutics to the CNS, as demonstrated in mice and non‐human primates. This universal platform, in general, enables the delivery of any protein therapeutics of interest to the brain, opening a new avenue for the treatment of CNS diseases.     

Performance analysis of a continuous bioreactor for ethanol and acetate synthesis from syngas via <Emphasis Type="Italic">Clostridium ljungdahlii</Emphasis> using exergy concept

In this paper, the exergetic performance of a continuous bioreactor for ethanol and acetate synthesis from syngas via a strictly anaerobic autotrophic bacterium Clostridium ljungdahlii was carried out for the first time. The fermentation process was evaluated using both conventional exergy and eco-exergy principles for measuring the productivity and renewability of the process at various liquid media flow rates. The microorganisms successfully upgraded the syngas into invaluable ethanol and acetate through the Wood–Ljungdahl pathway. The exergy efficiency was found to be in the range of 6.5–77.5 and 6.8–77.5 % during the fermentation using conventional exergy and eco-exergy concepts, respectively. The subtle differences observed in the exergetic parameters using the two exergetic concepts were ascribed to the slow growth rate of the microorganisms. Nevertheless, the eco-exergy concept would strongly be recommended for commercial bioreactor containing living organisms due to the inclusion of the information carried by microorganisms in the exergetic calculation. A desired liquid media flow rate of 0.55 mL/min was found according to a newly defined thermodynamic indictor namely exergetic productivity index. More specifically, the maximum exergetic productivity index of the fermentation process was found to be 8.0 using both approaches when the rate of inflow liquid was adjusted at the optimal value. The results of this study revealed that process yield alone cannot be a reliable performance metric for decision making on the productivity of various biofuel production pathways. Finally, the proposed exergetic framework could assist engineers and researchers to link biochemical and physical knowledge more robustly and to quantify and elucidate the general purpose of productivity and renewability.