Polyurethaneurea–silica nanocomposites: Preparation and investigation of the structure–property behavior

Nanocomposites consisting of thermoplastic polyurethane–urea (TPU) and silica nanoparticles of various size and filler loadings were prepared by solution blending and extensively characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermal analysis, tensile tests, and nanoindentation. TPU copolymer was based on a cycloaliphatic diisocyanate and poly(tetramethylene oxide) (PTMO-2000) soft segments and had urea hard segment content of 20% by weight. TPU/silica nanocomposites using silica particles of different size (29, 74 and 215 nm) and at different loadings (1, 5, 10, 20 and 40 wt. %) were prepared and characterized. Solution blending using isopropyl alcohol resulted in even distribution of silica nanoparticles in the polyurethane–urea matrix. FTIR spectroscopy indicated strong interactions between silica particles and polyether segments. Incorporation of silica nanoparticles of smaller size led to higher modulus and tensile strength of the nanocomposites, and elastomeric properties were retained. Increased filler content of up to about 20 wt. % resulted in materials with higher elastic moduli and tensile strength while the glass transition temperature remained the same. The fracture toughness increased relative to neat TPU regardless of the silica particle size. Improvements in tensile properties of the nanocomposites, particularly at intermediate silica loading levels and smaller particle size, are attributed to the interactions between the surface of silica nanoparticles and ether linkages of the polyether segments of the copolymers.     

Total Antioxidant Activity and Total Phenolic Contents in Different Turkish Eggplant (Solanum Melongena L.) Cultivars

In this study, total water soluble antioxidant activity and phenolic content of 26 eggplant ( Solanum melongena L. ) cultivars were investigated. Total water soluble antioxidant activity of the cultivars varied from 2664 to 8247 μmolTrolox/kg, which is a 3.1-fold difference. Cultivars also showed significant variation for total phenolic contents ranging from 615 to 1376 mg/kg, a 2.2-fold difference. The two traits were significantly correlated and results of this study suggested that breeders can use the information to develop eggplant cultivars with high antioxidant activity.     

An integrated maritime surveillance system based on high-frequencysurface-wave radars. 2. Operational status and system performance

For pt.1 see ibid., vol.43, no.4, p.28-43 (2001). An integrated maritime surveillance (IMS) system, based on high-frequency surface wave radars (HFSWR), for monitoring surface and low-level air activity within the 200 nautical mile (nm) Exclusive Economic Zone (EEZ) is described in this two-part paper. The science behind the long-range performance of HFSWR was presented in Part 1(Sevgi et al. 2001). The system described was installed on Canada's east coast, where it is being used to demonstrate continuous, all-weather surveillance of the EEZ to beyond 200 nm. The system consists of two land-based HFSWRs and an operations control center (OCC). The two unmanned radars provide coverage of the Grand Banks region of Newfoundland, renowned for its offshore resources, particularly fish and oil. The system has been designed to assist authorities to more efficiently monitor such illegal activities as drug trafficking, smuggling, piracy, illicit fishing and illegal immigration. In addition, the system may be used for tracking icebergs, environmental protection, search and rescue, resource protection, sovereignty monitoring, and remote sensing of ocean surface currents and winds. Extensive performance testing of the system has been conducted using the two fully functional radars. It is shown that the HFSWR system complements existing surveillance assets to dramatically increase the effectiveness of air and surface reconnaissance missions by vectoring them directly to targets of interest     

Effect of nanosphere size on the luminescence of synthetic opal

We have studied the effect of the stop band and coupled photonic modes on the visible luminescence of synthetic opal photonic crystals. The results demonstrate that the position of the photonic stop band in the luminescence spectrum of opal depends on the nanosphere diameter. Optical measurements have been used to determine the refractive index of the photonic crystals and the silica sphere diameter. We have assessed the effect of coupled modes in opal on its intrinsic luminescence spectrum. Coupled modes of visible light in opal can be visualized by applying a matte sapphire plate to the opal surface.     

Machine learning for human movement understanding

Main purpose of this project is to develop fundamental technology for assist robots to recover and maintain human motor skill and to extend scope of human activity. Our goal is to provide a system that adapts to its user’s personal behavior patterns in real-time. We aim to develop a continuous collaboration system between the assist robots and the user where both alternatively adjust to each other to maximize the system’s utility. To understand human movement, we recorded motion sequence of several tasks for different subjects using motion capture system. Through analysis of human motion data, we extracted a general model by rule-based approach. On the other hand, since such tasks are not feasible with static models, we investigate the potential benefit of supervised online learning in the task of online action classi?cation and Deep Learning in the task of acquiring human motion. Finally, developed system was extended to show its potential effect in ergonomics and in assist robotics.     

Research of both γ-irradiation and La2O3 addition on structural and magnetoresistivity of Bi-2223 bulk superconductors

In this study, we investigate the effects of both gamma irradiation and the addition of lanthanum oxide (La₂O₃) on the Bi_1.85Pb_0.35Sr₂Ca₂Cu₃O_y (Bi-2223) bulk superconductors. Pure and lanthanum-added samples prepared by the solid-state reaction method were analyzed before and after gamma irradiation using various methods such as X-ray powder diffraction (XRD), the temperature dependence of resistivity under magnetic field (ρ-T). Bi-2223 + x La₂O₃ samples with x = 0.0, 1.0 and 5.0 wt% were fabricated. The synthesized samples were then subjected to gamma irradiation at different intensities, and the effects of radiation on the structural, electrical, and magnetic properties of the materials were examined. For this purpose, Bi-2223 superconductors in the form of discs were produced and cut into two pieces. One piece was exposed to gamma radiation under high vacuum conditions. The phase analyzes of the materials were carried out by XRD. Then, electrical analysis of the materials was made by measuring resistance under a magnetic field.     

Method for the Synthesis of Optimum Multistage Heat Exchange Network

Theoretical Foundations of Chemical Engineering - A new algorithmic approach to the synthesis of economically optimum multistage heat exchange network in the design and reconstruction of...     

Computation of Compressible Gas Flow Using General-Purpose Graphics Processing Unit

Journal of Engineering Physics and Thermophysics - Possibilities for using general-purpose graphics processing units to simulate compressible gas flows are discussed. Consideration is given to...