Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy

The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications.     

Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization

The interaction of PLGA-chitosan Nanoplexes with ocular mucosa was investigated ex vivo and in vivo to assess their potential as ocular delivery system. Fluorescent Rhodamine Nanoplexes (Rd-Nanoplexes) were prepared by ionotropic gelation method. The size and morphology of Nanoplexes was investigated by TEM, SEM and PCS. The corneal retention, uptake and penetration of Nanoplexes were analyzed by spectrofluorimetry and confocal microscopy. Corneas from Rd-Nanoplexes-treated rabbits were evaluated for the in vivo uptake and ocular tolerance. The Nanoplexes prepared were round with a mean diameter of 115.6±17nm and the encapsulation efficiency of Rd was 59.4±2.5%. Data from ex vivo and in vivo studies showed that the amounts of Rd in the cornea were significantly higher for Nanoplexes than for a control Rd solution, these amounts being fairly constant for up to 24h. Confocal microscopy of the corneas revealed paracellular and transcellular uptake of the Nanoplexes. The uptake mechanism postulated was adsorptive-mediated endocytosis and opening of the tight junctions between epithelial cells. No alteration was microscopically observed after ocular surface exposure to Nanoplexes. Taken together, these data demonstrate that Nanoplexes are potentially useful as ocular drug carriers.     

Determination of flow parameters for pipe flows by the radiotracer techniques

In this study, the measurement of flow rate in pipes is obtained in the laboratory by two different radiotracing techniques, the peak to peak method and the radiotracer balance method. Sodium-24 has been used as the radiotracer and irradiation has been done in the I.T.U. TRIOA Mark-II Reactor. The peak to peak method is also applied with only one detector. The sensitivity of the methods are obtained for different conditions. Experimental results which are taken for the techniques are compared to each other and are evaluated with the flow parameters.     

PEGylated calix[4]arene as a carrier for a Bodipy-based photosensitizer

Heavy atom substituted Bodipy compounds, unlike the parent chromophore, undergo rapid intersystem crossing to generate singlet oxygen, which is the primary cytotoxic agent exploited in PDT. In this work, we show that an organic soluble calix[4]arene can be functionalized by Knoevenagel reaction and then converted into an amphiphilic photosensitizer in a few steps. In addition to generating a potentially useful photosensitizer, the sequence of reactions is the first use of a Bodipy dye as a chromophoric/fluorogenic label without the typical reactive functional groups.     

The effect of neutron and mixed gamma and neutron irradiation on the solar properties of borosilicate glass

Neutron and mixed gamma and neutron irradiation, at different absorbed doses, of borosilicate glass with four different chemical compositions was conducted to investigate the effects on the solar properties of the glass. Irradiation was performed in the tangential beam tube and central thimble of a nuclear reactor. The effect of thermal and epithermal neutrons on such solar properties as secondary heat-transfer factor, solar factor (the total solar energy transmittance), and shading coefficient of the borosilicate glass were investigated to determine the effect on the solar properties of borosilicate glass, because of its neutron absorbance property.     

Influence of material data input on accuracy of fatigue assessments for beam weldments

This numerical study investigates the effects of fatigue material data and finite element types on accuracy of residual life assessments under HCF conditions. The bending of cross-beam connections is simulated in ANSYS Workbench for three different combinations of beam profiles. The weldments are made of the high-strength steel grades C350LO and C450LO according to AS3678. The stress analysis of weldments is implemented with solid and shell elements using linear material and geometry consideration. The stress distributions are transferred to the embedded fatigue code nCode DesignLife. For both variants of FE-mesh, the nominal stress in the weld toes is extracted by splitting the total stress into membrane and bending components and filtering out non-linear component. Considering the effects of bending, size and mean stress, failure locations and fatigue life are predicted using the Volvo method and rules from ASME BPV Code. Three different pairs of experimental S-N curves (stiff and flexible) are used as material data input for fatigue analysis. The obtained numerical predictions are compared to the experimental results for shell FE-models. The predictions using the S-N curves for an equivalent steel demonstrate the best accuracy proving the fact that specific material data input is more effective than a generic data. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)