Sonochemically fabricated microelectrode arrays for biosensors. Part II. Modification with a polysiloxane coating

A polymer modified sonochemically fabricated glucose oxidase microelectrode array with microelectrode population densities of up to 2.5 x 105 microelectrodes cm-2 is reported. These microelectrode sensors were formed by first depositing an insulating film on commercial screen printed electrodes which was subsequently sonicated to form cavities of regular sizes in the film. Electropolymerisation of aniline at the microelectrode cavities formed polyaniline protrusions containing entrapped glucose oxidase. Chemical deposition of polysiloxane from dichlorodimethysilane was used to deposit a thin protective and diffusion mass transport controlling coating over the electrodes. The physical and electrochemical properties of these films were studied. The performance of the final glucose oxidase based microelectrode sensor array is reported

Determination of band bending at the Si(113) surface from photovoltage-induced core-level shifts

The Si 2p core levels were measured by photoelectron spectroscopy with use of synchrotron radiation for the clean Si(113) 3×2 surface. The core levels exhibit shifts of several hundred meV during the change of sample temperature from 300 to 20 K. We interpret these shifts as due to a release of band bending by saturation surface photovoltage. Together with core-level spectroscopy, this turns out to be a new, highly accurate method in determining Fermi-level pinning. For the clean Si(113) 3×2 surface the pinning position coincides within 25 meV for n- and p-type doped samples. At 20 K, a strong reduction of the Si 2p linewidth is found for the p-type sample, which is only to a lesser degree due to band flattening. An intrinsic linewidth of the Si 2p core level of 205±30 meV is derived

Adatom-induced donor states during the early stages of Schottky-barrier formation: Ga, In, and Pb on Si(113)

We performed angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy for the early stages of Schottky-barrier formation of Ga, In, and Pb on Si(113) at room temperature. In the coverage region below 0.1 monolayer a band-bending behavior, typical for donor states, is found. The energies of the adatom-induced donor states in the band gap depend on the adatoms. The Schottky barrier reaches its final value at a coverage of about one monolayer. The values are 0.35 eV above the valence-band maximum for In and Ga and 0.425 eV for Pb. Measurements with Xe interlayers were made to verify that these interfaces are not reactive

Band bending in the initial stages of Schottky-barrier formation for gallium on Si(113)

We present angle-resolved ultraviolet and soft-x-ray photoelectron spectroscopy results for the Schottky-barrier formation of Ga on p-type Si(113). For the first 0.08 monolayer of Ga, the band bending increases. For higher coverages, it decreases monotonically until it reaches its final value at about 2 monolayers. This change of band bending is found for a Si surface for the first time and supports a recent model calculation. The final barrier height is 0.32±0.10 eV, in good agreement with the values found for low-index surfaces

Micromechanical finite element analyses of fire retardant woven fabric composites at elevated temperatures using unit cells at multiple length scales

This paper presents a micromechanical Finite Element (FE) model developed to predict the effective mechanical properties of glass fibre-reinforced (woven fabric) polymer composites with/without fire retardant particulate additives at elevated temperatures. The elevated mechanical properties of glass fibre-reinforced epoxy composites with/without fire retardants were predicted using three unit cells of varying length scales in micromechanical FE analysis. Theoretically predictions of flexural behaviour of these fibre-reinforced polymer composites at elevated temperatures were satisfactorily validated against experimentally measured data. The numerical model developed herein was then used for the prediction of other mechanical properties of fibre-reinforced polymer composites that would have been difficult to collect at elevated temperatures. Micromechanical FE models such as the one contained in this paper are useful to architectural engineers as they can be used to guide the design and qualification of new engineering composites that satisfy stringent Building codes in fire prone engineering applications

Serodiagnosis of leishmaniasis with recombinant ORFF antigen

The serodiagnostic potential of recombinant ORFF protein (rORFF) from Leishmania infantum was assessed by ELISA. Of 49 sera from confirmed cases of visceral leishmaniasis (VL), all were seropositive using 5 ng of rORFF and serum diluted 1:20, while only 38 were positive with 500 ng of soluble antigen (SA) and 44 were positive by a direct agglutination test. There was also a positive correlation between spleen size and level of seropositivity with rORFF or SA. The reciprocal endpoint titer with rORFF was 1,280 for sera from VL patients, but < 20 with sera from malaria, filariasis, and tuberculosis patients, as well as with sera from healthy individuals from endemic and non-endemic areas. Sera from 10 confirmed cutaneous leishmaniasis cases from Turkey were negative or only weakly positive with rORFF although 9 were positive with SA. Thus, rORFF protein appears useful as a sensitive reagent for the differential diagnosis of VL caused by the Leishmania donovani complex

NMR structure of an acyl-carrier protein from Borrelia burgdorferi

The high-resolution NMR structure of the acyl-carrier protein from the pathogen B. burgdorferi determined to a r.m.s. deviation of 0.4 Å over the protein backbone is reported. The NMR structure was determined using multidimensional NMR spectroscopy and consists of four α-helices and two 310-helices. Structural comparison reveals that this protein is highly similar to the acyl-carrier protein from A. aeolicus

Discovery of a natural product that binds to the mycobacterium tuberculosis protein Rv1466 using native mass spectrometry

Elucidation of the mechanism of action of compounds with cellular bioactivity is important for progressing compounds into future drug development. In recent years, phenotype-based drug discovery has become the dominant approach to drug discovery over target-based drug discovery, which relies on the knowledge of a specific drug target of a disease. Still, when targeting an infectious disease via a high throughput phenotypic assay it is highly advantageous to identifying the compound’s cellular activity. A fraction derived from the plant Polyalthia sp. showed activity against Mycobacterium tuberculosis at 62.5 µge/µL. A known compound, altholactone, was identified from this fraction that showed activity towards M. tuberculosis at an minimum inhibitory concentration (MIC) of 64 µM. Retrospective analysis of a target-based screen against a TB proteome panel using native mass spectrometry established that the active fraction was bound to the mycobacterial protein Rv1466 with an estimated pseudo-Kd of 42.0 ± 6.1 µM. Our findings established Rv1466 as the potential molecular target of altholactone, which is responsible for the observed in vivo toxicity towards M. tuberculosis

Radically different maxicircle classes within the same kinetoplast: an artefact or a novel feature of the kinetoplast genome?

We discuss here some results which suggest that radically different maxicircle classes coexist within the same kinetoplast. These data, although tentative and incomplete, may provide a new outlook on the kinetoplast genome structure and expression

Using student data: Student-staff collaborative development of compassionate pedagogic interventions based on learning analytics and mentoring

UK Universities are increasingly being ‘encouraged’ to focus on student engagement, retention and performance, with learning analytics becoming commonplace. Based on inter-related student-staff partnerships, this study adopted a human and compassionate approach to the use of student data and subsequent interventions. Analysis of focus group and interview data from 86 student participants explored key themes: peer-mentoring increasing engagement with the communal-habitus; increased confidence and engagement; and the demystification and humanisation of the university environment. Findings highlight the importance of emphasising human and compassionate support for students within rapidly developing learning analytics approaches, with subject-specific peer-mentoring found here to be beneficial