Nitrooleate Mediates Nitric Oxide Synthase Activation in Endothelial Cells

Nitrated lipids such as nitrooleate (OLA-NO₂) can act as endogenous peroxisome proliferator-activated receptor gamma (PPARγ) ligands to exert vascular protective effects. However, the molecular mechanisms regarding nitric oxide (NO) production and its regulation are not fully defined in the vasculature. Here, we show that OLA-NO₂ increased endothelial NO release by modulating activation of endothelial nitric oxide synthase (eNOS) in endothelial cells. Treatment with OLA-NO₂ (3 μM) increased NO release in a time-dependent manner. OLA-NO₂ decreased protein expression of eNOS and caveolin-1 (Cav-1) but increased heat shock protein 90 (Hsp90) expression. Immunoprecipitation analysis confirmed that OLA-NO₂ replaced eNOS/Cav-1 with eNOS/Hsp90 interaction, resulting in increasing eNOS activity. OLA-NO₂ also induced eNOS phosphorylation at Ser633 and Ser1177 and eNOS dephosphorylation at Ser113 and Thr495. In addition, OLA-NO₂ induced phosphorylation of Akt and extracellular signal-regulated protein kinase (ERK1/2), which might contribute to eNOS activation. Collectively, these results substantiate a new functional role for nitrated fatty acid, demonstrating that OLA-NO₂ exerts vascular protective effects by increasing NO bioavailability through eNOS phosphorylation/dephosphorylation and interaction with associated proteins such as Hsp90 and Cav-1.     

Effect of an Orifice on Collection Efficiency and Wall Loss of a Slit Virtual Impactor

The effect of an orifice on the collection efficiency and wall loss of a slit virtual impactor was investigated both numerically and experimentally. The ratios of the collection nozzle width (W_c ), distance between acceleration nozzle and collection nozzle (S), length of acceleration nozzle (T), inlet width (D), and nozzle span (l) to the acceleration nozzle width (W_a ) were fixed at W_c /W_a = 1.4, S/W_a = 1.5, T/W_a = 1.1, D/W_a = 6, and l/W_a = 10, respectively. The minor-to-total flow ratio was set to 0.1 in laminar flow regime. The collection efficiency and wall loss of the slit virtual impactor were found to be characterized by the square root of the Stokes number. For the slit virtual impactor without an orifice, the square root of the Stokes number corresponding to the cut-off diameter was determined to be (Stk₅₀)^1/2 = 0.77 and the maximum wall loss at the collection nozzle reached 30% or 40%. When an orifice having the same width as the acceleration nozzle was placed upstream of the acceleration nozzle at a distance of 20W_a , the value of (Stk₅₀)^1/2 decreased to 0.68 and the wall loss at the collection nozzle decreased below 5%.

Copyright 2014 American Association for Aerosol Research     

Predictive position and force control for shape memory alloy cylinders

In this paper, a linear lightweight electric cylinder constructed using shape memory alloy (SMA) is proposed. Spring SMA is used as the actuator to control the position and force of the cylinder rod. The model predictive control algorithm is investigated to compensate SMA hysteresis phenomenon and control the cylinder. In the predictive algorithm, the future output of the cylinder is computed based on the cylinder model, and the control signal is computed to minimize the error and power criterion. The cylinder model parameters are estimated by an online identification algorithm. Experimental results show that the SMA cylinder is able to precisely control position and force by using the predictive control strategy though the hysteresis effect existing in the actuator. The performance of the proposed controller is compared with that of a conventional PID controller.     

沿岸及内陆风机塔筒的防腐涂料与涂装体系

针对不同腐蚀环境,介绍了内陆和近海沿岸地区风机塔筒的防腐涂料与涂装体系。讨论了风机涂装体系中的面漆和水性涂料体系设计方案。     

Mn3O4 nanoparticles embedded into graphene nanosheets: Preparation, characterization, and electrochemical properties for supercapacitors

Mn₃O₄/graphene nanocomposites were synthesized by mixing graphene suspension in ethylene glycol with MnO₂ organosol, followed by subsequent ultrasonication processing and heat treatment. The as-prepared product consists of nanosized Mn₃O₄ particles homogeneously distributed on graphene nanosheets, which has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis. Atomic force microscope analysis further identified the distribution of dense Mn₃O₄ nanoparticles on graphene nanosheets. When used as electrode materials in supercapacitors, Mn₃O₄/graphene nanocomposites exhibited a high specific capacitance of 175 F g⁻¹ in 1 M Na₂SO₄ electrolyte and 256 F g⁻¹ in 6 M KOH electrolyte, respectively. The enhanced supercapacitance of Mn₃O₄/graphene nanocomposites could be ascribed to both electrochemical contributions of Mn₃O₄ nanoparticles, functional groups attached to graphene nanosheets, and significantly increased specific surface area.     

Preparation and properties of bio‐nanoreinforced composites from biodegradable polymer matrix and cellulose whiskers

Crystalline cellulose was extracted from one of the cheapest source; grass by alkali, acid, and mechanical treatments. To evaluate the reinforcing effect of this filler, biodegradable polymer matrix, polylactic acid (PLA) was used and samples were prepared at different concentrations. The modified whiskers were also used as filler to examine the effect on mechanical properties. Crystallinity, thermal behavior, surface morphology and functional group variation was monitored through, XRD, TGA, SEM, and FTIR respectively. The properties were largely depending on the concentration of filler whereas; modification of hydroxyl groups did not exhibit remarkable change in mechanical properties. Thermal resistance was decreased in comparison of neat matrix and reduction in crystallinity was also observed for composites, regardless of filler nature. It was thought that the hydrophilicity of cellulose could be altered by modifying its hydroxyl groups, thereby promoting dispersion. However, the possibility of phase separation was increased, and the thermal stability of the composites gradually decreased with increasing filler load in the matrix. In the examined systems, it was observed that improvement of reinforcing capacity may not only depend on the chemical compatibility between matrixes but also some compositional and physical parameters may be responsible for variation in properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ultrasound assisted batch-processing of EVA-organoclay nanocomposites

The aim of this study was to investigate the effect of ultrasound on the properties of a poly[ethylene-co-(vinyl acetate)] (EVA)-organoclay nanocomposite. By using a torque rheometer, in-situ rheological behaviors of various EVA resins with varying VA content were examined. It was found that the effect of ultrasound was most significant for EVA 31 (31 wt% VA). EVA31/organoclay nanocomposites were prepared in batch mixer with and without irradiation of ultrasound. The characterization of the nanocomposite was performed using XRD, TEM, rheometry, and universal testing machine. XRD and TEM results revealed that the produced EVA31/organoclay nanocomposite with ultrasonic irradiation possessed intercalated structure. Rheometry result indicated that EVA31/organoclay nanocomposite processed with ultrasound had a highly disordered or delaminated structure. A considerable increase in stiffness and Young’s modulus for the sonicated nanocomposite compared to those for unsonicated one was obtained. This study demonstrated the possibility of producing EVA-organoclay nanocomposites with enhanced dispersion of nanoclays using ultrasound assisted processing.     

Recent Advances in the Application of Natural Fiber Based Composites

Natural fiber reinforced polymer composites are lightweight, economical and available in a variety of forms. They have low densities, comparable material properties, high molding flexibility and are environmentally friendly, making them a conceivable alternative to traditional fillers like mica, calcium carbonate and glass. By modifying either the resin system or the natural fiber, biocomposites can be designed for different applications ranging from products of commodity to aerospace, examples including electroactive papers, fuel cell membranes, controlled drug release mechanisms and biosensors. This review aims to analyze the advancement in the application of cellulose based materials in different sectors with a discussion of fundamental research in these areas.

     

Frictionally excited thermo-elastoplastic instability

A transient finite element simulation is used to solve the two-dimensional contact problem involving thermo-elastoplastic instability (TEPI) in frictional sliding system. The existence of plastic deformation below the critical speed for thermoelastic instability is independent of the size of initial perturbation. For the simulation of the first/second partial contact, the amount of initial perturbation affects only the time interval of the first partial contact and the second partial contact is reached earlier, regardless of the initial perturbation. In addition, it shows that the locations of hot spots after cooling are changed.     

Preparation and characterization of titania/ZnS core-shell nanotubes

Core-shell nanocomposites of titania nanotubes/ZnS quantum dots have been prepared by using a hydrothermal synthetic method and characterized by using various microscopic and spectroscopic methods. ZnS quantum dots surround the outsides of titania nanotubes having the inner and the outer diameters of 15 and 30 nm, respectively, with a thickness of 2 nm. The nanocomposites suspended in water show a broader absorption spectrum shifted to a longer wavelength by 20 nm and emit substantially stronger ZnS luminescence having significantly slower decay kinetics than bare ZnS nanoparticles in water. The support of TiO2 nanotubes is found to enhance the optical properties of ZnS considerably.