Myoglobin adsorption onto poly(glycidyl methacrylate) microbeads with surface functionalized iminodiacetic acid

In this study, poly(glycidyl methacrylate) [PGMA] microbeads with surface modified iminodiacetic acid (IDA) were used for myoglobin (Mb) adsorption from buffer solutions at different pHs and ionic strengths in a packed-bed column. Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) measurements before and after the adsorption process confirmed the structural stability of adsorbed Mb. The effects of initial concentration, flow-rate, pH and ionic strength on the adsorption were investigated. The results showed that the maximum amount of protein was adsorbed at a pH 7.0, which is the protein isoelectric point. The adsorption is rationalized in terms of local electrostatic forces acting between the protein and the IDA modified PGMA surface as well as hydrophobic interactions close to the protein isoelectric point, whereas at low pH the global changes give rise to protein–protein repulsion and at high pH protein-support material repulsion.     

Effects of environmental factors on the adhesion and durability characteristics of epoxy-bonded concrete prisms

This work is concerned with the effects of environmental factors on the adhesion and durability characteristics of epoxy-bonded concrete prisms. The results indicate that the presence of liquid water at the interfacial zone during the epoxy injection process disrupts the initial bond configurations. The freezing and thawing up to about 40 cycles do not have a significant effect on the bond stability. An adequate degree of chemical stability is maintained in the bond line by the epoxy adhesives after 120 days of exposure to corrosive environments such as MgSO₄ and MgCl₂. However, there is a pronounced effect of these chemical substances on the concrete strength. The load-bearing capacity of epoxy-bonded concrete prisms decreases with increasing temperature. Despite this fact, the EP3-bonded concrete prisms give relatively high joint strengths at temperatures up to 100 °C.     

Synthesis of bio‐based polymeric nanocomposites from acrylated epoxidized soybean oil and montmorillonite clay in the presence of a bio‐based intercalant

Polymeric nanocomposites were synthesized from functionalized soybean‐oil‐based polymer matrix and montmorillonite (MMT) clay using an in situ free radical polymerization reaction. Acrylated epoxidized soybean oil combined with styrene was used as the monomer. Organophilic MMT (OrgMMT) was obtained using a quaternized derivative of methyl oleate, which was synthesized from olive oil triglyceride, as a renewable intercalant. The resultant nanocomposites were characterized using X‐ray diffraction and atomic force microscopy. The effect of increased nanofiller loading on the thermal and mechanical properties of the nanocomposites was investigated using thermogravimetric analysis and dynamic mechanical analysis. It was found that the desired exfoliated nanocomposite structure was achieved when the OrgMMT loading was 1 and 2 wt%, whereas a partially exfoliated or intercalated nanocomposite was obtained for 3 wt% loading. All the nanocomposites were found to have improved thermal and mechanical properties as compared with virgin acrylated epoxidized soybean‐oil‐based polymer matrix. The nanocomposite containing 2 wt% OrgMMT clay was found to have the highest thermal stability and best dynamic mechanical performance. Copyright © 2010 Society of Chemical Industry     

Novel method for the analysis of RLC circuits

The lagrangian formulation of classical mechanics is applied to RLC circuits. The generalized power function is introduced and the reduced Lagrange equations are used in the analysis of the system. This new method seems to be more useful than the conventional Kirchhoff taws and Lagrange equations. This is illustrated by an example.     

Numerical Study on Heat Transfer Between Turbulent Flow and Porous Rectangular Cylinders with Uniform Injection or Suction

The heat transfer characteristics of the flow around rectangular cylinders having various aspect ratios with uniform injection or suction through the rear, top, bottom, and all surfaces have been studied numerically. The effects of injection or suction on heat transfer have been linked to the analysis via wall functions of the velocity and temperature sublayers. The computational code employed in the present study was verified with a typical benchmark problem of the flow around a square cylinder. The results show that the heat transfer between the main flow and rectangular cylinders is substantially influenced by injection or suction—that is, suction enhances the heat transfer, while injection through the rear surface provides some thermal protection.     

Effect of Ti amount on wear and corrosion properties of Ti-doped Al2O3 nanocomposite ceramic coated CP titanium implant material

Al₂O₃ and Ti-doped Al₂O₃ nanocomposite ceramic coatings were prepared by using a sol-gel dip-coating process. Corrosion and wear resistance of Al₂O₃ ceramic coatings in relation to Ti amount were carried out using pin-on-disk tribotester, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Surface characterizations before and after the corrosion and wear tests were investigated by the scanning electron microscope (SEM) and X-ray diffraction (XRD) and hardness analysis. The results of corrosion and wear tests exhibited that the corrosion and wear resistance of nanocomposite ceramic coatings became better than uncoated samples. Also, corrosion and wear resistance of nanocomposite ceramic coatings improved with Ti doping content increased.     

Hemocompatibility,cytotoxicity, and genotoxicity of poly(methylmethacrylate)/nanohydroxyapatite nanocomposites synthesized by melt blending method

The aim of this study was to show the hemocompatibility, cytotoxicity, and genotoxicity of nanocomposites that were synthesized with different molecular weights of poly(methyl methacrylate) (PMMA) and different concentrations of nanohydroxyapatite (nHAp). Different techniques to characterize the nanocomposites were used. The cytotoxicity and genotoxic effects of the polymers and nanocomposites on human lymphocytes were determined by acid phosphatase assay, viability test, and comet assay. Moreover, hemocompatibility test was performed. It was found that all of the PMMA/nHAp nanocomposites are highly hemocompatible and biocompatible, none of the nanocomposites showed a cytotoxic effect, and nHAp addition decreased the genotoxicity.     

Synthesis,Characterization, and In Vitro Bioactivity of Sol‐Gel‐Derived Zn,Mg, and Zn‐Mg Co‐Doped Bioactive Glasses

Bioactive glasses in the systems CaO‐SiO₂‐P₂O₅‐ZnO, CaO‐SiO₂‐P₂O₅‐MgO, and CaO‐SiO₂‐P₂O₅‐MgO‐ZnO were prepared and characterized. Bioactive glass powders were produced by the sol‐gel method. The prepared bioactive glass powders were immersed in a simulated body fluid (SBF) for periods of up to 28 days at 310 K to investigate the bioactivity of the produced samples. Inductively coupled plasma (ICP) and ultraviolet (UV) spectroscopic techniques were used to detect changes in the SBF composition. X‐Ray diffraction (XRD) was utilized to recognize and confirm the formation of a hydroxyapatite (HA) layer on the bioactive glass powders. Microstructural characterizations of the bioactive glass samples were investigated by scanning electron microscopy (SEM) techniques. Density, porosity, and surface area values of bioactive glass powders were also determined in order to characterize the textural properties of the samples. The results revealed the growth of an HA layer on the surface of the bioactive glass samples. MgO in the glass sample increases the rate of formation of an HA layer while ZnO in the glass slows it down.     

The preparation of core–shell Al2O3/Ni composite powders by electroless plating

Core–shell nanostructured Ni-coated Al₂O₃ composite powders were synthesised by using the electroless plating method. The influence of the chemical components and powder concentration in the Ni coating was investigated by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction techniques. The results show that the concentration of the plating components plays an important role in the formation of core–shell Al₂O₃/Ni composite powders. The nickel content in the composite powders could be effectively controlled by adjusting the nickel chloride content and the concentration of NaH₂PO₂·H₂O in the plating solution. The nanostructure of the crystalline Ni coatings was observed to be very attractive for achieving good bonding between ceramic particles and matrices for composite production.     

The investigation of the effect of thermal barrier coating on the performance of Stirling engine

The shuttle heat transfer is one of the reasons reducing the performance of Stirling engines. This study is concerned with the reduction in shuttle heat transfer by coating the displacer. The displacer of a gamma type Stirling engine was coated with a layer of yttria‐stabilized zirconia (YSZ), and the effect of the coating on the engine performance was evaluated by comparing speed‐power and speed‐torque characteristics of the engine with coated and uncoated displacers. Characteristics were obtained for 700, 800 and 900°C heater temperatures. At each stage of the heater temperature, the charge pressure ranged from 1 to 3.5 bars with 0.5 bar increments. At 900°C heater temperature and 3 bars charge pressure, the shaft power before coating was 34.9 W, after coating the power increased to 43.8 W, which corresponds to a 25% increment. The temperature applied to the engine did not cause any damage on the coating layer. Copyright © 2008 John Wiley & Sons, Ltd.