CHARACTERIZATION OF 6061 T651 ALUMINUM PLATES SUBJECTED TO HIGH-VELOCITY IMPACT LOADS

Ballistic response of single or multi-layered metal armor systems subjected to kinetic energy pro-jectiles was investigated in many experimental, theoretical and numerical studies.In this study, 6061 T651 aluminum plates impacted by 9 mm bullets were investigated. Microstructural investigations have been carried out using optical microscopy. Microhardness values were used to determine the strength behavior of the plates. Influence of the plate thickness and impact velocity on the microstructure has been evaluated. It was concluded from the study that thinner plates are more prone to deformation hardening with high penetration depth values even at low impact velocities while thick plates are more susceptible to thermal softening with less penetration depths. Maximum hardness values were obtained just below the impact zone in both plate thicknesses

Staged thermomechanical testing of nickel superalloys produced by selective laser melting

The creep performance of additively manufactured components remains an issue before additive manufacturing can be put fully implemented. In this study, Inconel 718 two-bar specimens are produced by selective laser melting and subjected to a ‘staged’ creep test. Creep test was interrupted at critical junctures and X-ray computed tomography measurements performed at various extensions of the specimen. Periodic X-ray computed tomography measurements allow, for the first time, examination of the specimens during creep testing. Evaluation of specimen performance shows the number and size of pores within the specimen increasing over time as a result of classical creep mechanisms. Location and tracking over time of weak points are performed, allowing early estimation of sample failure points. This information is valuable to selective laser melting practitioners who seek to optimise the build strategy in order to minimise in-built defects

An electrochemical immunosensor based on a 4,4′-thiobisbenzenethiol self-assembled monolayer for the detection of hemagglutinin from avian influenza virus H5N1

An electrochemical immunosensor for the detection of hemagglutinin from avian influenza virus H5N1 is presented in this paper. The following steps lead up to the construction of immunosensor: (i) modification of gold electrodes with 4,4′-thiobisbenzenethiol, (ii) modification of self-assembled monolayer of 4,4′-thiobisbenzenethiol with gold colloidal nanoparticles, (iii) immobilization of single chain variable fragments of antibodies (scFv) against hemagglutinin H5 via Ssingle bondAu covalent bonds, (iv) blocking of the remaining free space with bovine serum albumin. The interactions between the scFv and hemagglutinin variants have been explored with electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4− as an electroactive marker. The immunosensor was able to detect two different His-tagged variants of recombinant hemagglutinin from H5N1 viruses: the short fragment (17–340 residues) of A/swan/Poland/305-135V08/2006 and the long (17–530 residues) of A/Bar-headed Goose/Qinghai/12/2005. The strongest response has been observed for the long variant with a detection limit of 0.6 pg/mL and a dynamic range from 4.0 to 20.0 pg/mL. The recombinant hemagglutinin (17–527 residues) from A/chicken/Netherlands/1/03 (H7N7), used as the negative control generated a weak response. This confirms the selectivity of the immunsensor proposed. A miniaturized version of the immunosensor, based on screen-printed gold electrodes, was tested with the same set of recombinant hemagglutinins and it achieved a linear range from 1 to 8 pg/mL with a detection limit of 0.9 pg/mL for the long fragment of hemagglutinin

In-situ secondary growth of nanocube-based Prussian-blue film as an ultrasensitive biosensor

A regular nanostructure has been widely confirmed to result ina marked improvement in material performance in biosensing applications. In the present study, a regular nanostructured Prussian blue (PB) film with two heterogeneous crystal layers was synthesized in-situ using a secondary growth method. A PB seed layer was first controlled to form uniform cube-like crystal nuclei through an ultrasonic reaction with a single reactant. Then, well-defined 100 nm PB nanocubes were further crystallized on this seed layer using a self-assembly approach. In order to accelerate the electron transfer rate during the enzyme reaction for glucose detection, the graphene was used as the main cross-linker to immobilize glucose oxidase on the PB film. The as-prepared biosensor exhibited high electrocatalysis and electron conductivity for the detection of trace glucose with a sensitivity of 141.5 µA mM-1 cm-2, as well as excellent anti-interference ability in the presence of ascorbic acid and uric acid under a low operation potential of -0.05 V

Boronic acids for sensing and other applications - a mini-review of papers published in 2013

Boronic acids are increasingly utilised in diverse areas of research. Including the interactions of boronic acids with diols and strong Lewis bases as fluoride or cyanide anions, which leads to their utility in various sensing applications. The sensing applications can be homogeneous assays or heterogeneous detection. Detection can be at the interface of the sensing material or within the bulk sample. Furthermore, the key interaction of boronic acids with diols allows utilisation in various areas ranging from biological labelling, protein manipulation and modification, separation and the development of therapeutics. All the above uses and applications are covered by this mini-review of papers published during 2013