Effect of Dispersants on the Electrophoretic Deposition of Hydroxyapatite‐Carbon Nanotubes Nanocomposite Coatings

Isopropanolic Suspensions of HA nanoparticles (20 g/L) plus various concentrations of carbon nanotubes (CNTs) were prepared using Tris and triethanolamine as dispersant. The positively charged HA nanoparticles were heterocoagulated on the negatively charged CNTs and generated the HA‐CNT composite particles with net positive surface charge. The heterocoagulation was more intensive in dispersant‐containing suspensions (DCS) due to the higher zeta potential of HA nanoparticles in them. HA‐CNTs particles can be rotated and aligned parallel to electric field as a result of torque exerted on them due to the generation of a dipole moment in CNTs during electrophoretic deposition (EPD). The mobility of HA‐CNTs particles aligned parallel to electric field is ≈50% higher than that of HA nanoparticles leading to the faster EPD from DCS when CNTs are added into them. CNTs more efficiently reinforced the coatings deposited from DCS due to the stronger electrostatic bonding between CNTs and HA nanoparticles in them.     

Development of T type zeolite for separation of CO2 from CH4 in adsorption processes

Influence of synthesis parameters; silica sources, relative alkalinity and silicon module, were investigated on preparation of T type zeolite by hydrothermal method, using a two level factorial design. Crystallization time and reaction temperature were held constant at 7 days and 378 K, respectively. The synthesized products were characterized by XRD and SEM techniques. The results showed that increasing silicon module and decreasing relative alkalinity in the synthesis gel improved the product relative crystallinity. It was also observed that using colloidal silica as the silica source improved crystallinity and phase purity of T type zeolites. The prepared zeolite T with the highest relative crystallinity was examined in the batch adsorption experiments at three temperatures of 288, 298 and 308 K and various pressures from 0.1 up to 2 MPa to verify the ability of the material for selective adsorption and separation of CO₂ from CH₄. The adsorption capacities and isotherms of CO₂ and CH₄ were determined at the studied temperatures. The results showed that the highest ideal selectivity of CO₂/CH₄ could be achieved at atmospheric pressure and 308 K. The performance of the adsorbent was confirmed with breakthrough curves and breakthrough times resulted from dynamic adsorption experiments of the mixed gases.     

Effect of silicon carbide nanoparticles on the adhesion strength of steel–epoxy composite joints bonded with acrylic adhesives

This paper reports a study on the effect of silicon carbide nanoparticles on the adhesion strength of steel–glass/epoxy composite joints bonded with two-part structural acrylic adhesives. The introduction of nanosilicon carbide in the two-part acrylic adhesive led to a remarkable enhancement in the shear and tensile strength of the composite joints. The shear and tensile strengths of the adhesive joints increased with adding the filler content up to 1.5?wt%, after which decreased with adding more filler content. Also, addition of nanoparticles caused a reduction in the peel strength of the joints. DSC analysis revealed that Tg values of the adhesives rose with increase in the nanofiller content. The equilibrium water contact angle was decreased for adhesives containing nanoparticles. SEM micrographs revealed that addition of nanoparticles altered the fracture morphology from smooth to rough fracture surfaces.     

The effect of surface strands,angle of attack,and ice accretion on the flow field around electrical power cables

The influence of surface strands, angle of attack, and ice accumulation on the flow field around electrical power cables of various geometries is not clearly understood. The purpose of this study was to examine the effect of these factors on the near wake flow field of three stationary wind tunnel models, namely, Model 1 (smooth and heavily iced), Model 2 (stranded and lightly iced), and Model 3 (stranded and heavily iced). Some angles of attack, θ, significantly altered the flow field by encouraging a rise in Strouhal number for all models at θ=0°, for Model 2 at θ=150–160°, and for Model 3 at θ=180°. Under certain conditions (θ=0°, U >22 m/s, Re>42,000) for Model 3, dual vortex shedding frequency peaks were present. These changes in Strouhal number may potentially predispose models to low drag and high lift forces.     

Strengthening of polysulfone membranes using hybrid mixtures of micro- and nano-scale modifiers

Polysulfone (PSf) membranes were modified by either a new organic modifier (sulfonated poly(ether sulfide sulfone), SPESS) or a traditional modifier (rice hulk). These membranes were further reinforced with either multi-walled carbon nanotubes (MWCNTs) or silica nanoparticles. Having a dye rejection of 98.46%, the reinforced membranes increased more than 50% in strength but no change in solution flux was observed. The morphological and roughness studies were conducted using scanning electron microscopy and atomic force microscopy. Moreover, the PSF membranes were also characterized by differential scanning calorimetry. Modifying the membranes with organic modifier or nanofiller increases the glass transition temperature (T _g ). The highest T _g and strength were observed for the PSf-SPESSMWCNT membrane. SPESS decreases surface roughness but MWCNT increases roughness on the nanoscale. All membranes show a bimodal pore size distribution, whereas the PSf-SPESS-MWCNT membrane exhibits a relatively uniform distribution of macroscopic and microscopic pores.

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Preparation and characterization of Calendula officinalis-loaded PCL/gum arabic nanocomposite scaffolds for wound healing applications

Medicinal plants such as Calendula officinalis (C. officinalis) are commonly used for skin wounds’ treatment. On the other hand, gum arabic (GA) has a lot of potential for use in wound healing because of its unique physio-chemical properties. Wound healing activity of gum arabic (GA) and Calendula officinalis (C. officinalis) along with good mechanical properties of poly (ε-caprolactone) (PCL) can produce a suitable nanofibrous scaffold for skin tissue engineering as well as wound dressing application. In this study, PCL/C. officinalis/GA nanofibrous scaffolds with diameter distribution in the range of 85–290 nm were prepared via electrospinning. Characteristics of the nanofibrous scaffolds, i.e., morphology, scaffold compounds, porosity, mechanical and antibacterial properties, hydrophilicity and degradability in phosphate buffer saline (PBS) were investigated. Cell viability and proliferation of scaffolds were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay. Results indicated that hydrophilicity of the PCL/C. officinalis/GA scaffolds was higher than the PCL scaffold. The tensile strength and elongation of the PCL/C. officinalis/GA scaffolds were in the range of 2.13–4.41 MPa and 26.37–74.37%, respectively, which are very suitable for skin tissue engineering. The porosity of the scaffolds was higher than 60% and was appropriate for the proliferation of fibroblast cells. The nanocomposite scaffold also showed suitable degradability and antimicrobial activity. Moreover, cell culture indicated that GA and C. officinalis promoted cell attachment and proliferation. It can be concluded that the nanofibrous calendula-loaded PCL/GA scaffolds are well suited for regenerating skin.

     

Sensor Fusion for SLAM Based on Information Theory

We present a sensor fusion management technique based on information theory in order to reduce the uncertainty of map features and the robot position in SLAM. The method is general, has no extra postulated conditions, and its implementation is straightforward. We calculate an entropy weight matrix which combines the measurements and covariance of each sensor device to enhance reliability and robustness. We also suggest an information theoretic algorithm via computing the error entropy to confirm the relevant features for associative feature determination. We validate the proposed sensor fusion strategy in EKF-SLAM and compare its performance with an implementation without sensor fusion. The simulated and real experimental studies demonstrate that this sensor fusion management can reduce the uncertainty of map features as well as the robot pose.