The kinetics of silver iodide film formation on the silver anode

The potentiodynamic formation of AgI films by reaction (1) on an Ag rotating disc electrode was studied and the results were compared to previous work regarding the formation of anodic AgBr and Ag₂S films,

In dilute iodide solutions, a very porous AgI film is formed at a rate controlled by the diffusion of I^? to the electrode surface. At higher iodide concentrations, and particularly in high conductivity supporting electrolytes, a porous AgI film forms at a rate initially limited by ionic migration in solution followed by diffusion of I^? in the pores of the AgI film.In 1 M NaI solutions, when AgI becomes rather soluble, thick granular AgI films form at a rate limited by the solid-state migration of ions in the bulk of the film. On the basis of the low-field model of film growth, the ionic conductivity of these AgI films has been determined to be 8.7 × 10^?5 Scm^?1     

Stable dye-labelled oligonucleotide-nanoparticle conjugates for nucleic acid detection

Metallic nanoparticles functionalized with oligonucleotides are used for a number of nucleic acid detection strategies. However, oligonucleotide-nanoparticle conjugates suffer from a lack of stability when exposed to certain conditions associated with DNA detection assays. In this study, we report the synthesis of thiol and thioctic acid-modified oligonucleotide gold nanoparticle (OGNs) conjugates functionalized with a dye label and varying spacer groups. The thioctic acid-modified conjugates exhibit increased stability when treated with dithiothreitol (DTT) compared to the more commonly used thiol modification. When the dye labelled oligonucleotide nanoparticle conjugates are exposed to the same conditions there is a pronounced increase in the stability for both thioctic acid and thiol modified sequences. These results open up the possibility of simply using a dye label to enhance the stability of oligonucleotide-nanoparticle conjugates in DNA detection assays where the enhanced stability of the conjugate system can be advantageous in more complex biological environments.     

Reprint of: Oxidative dehydrogenation of cyclohexane and cyclohexene over supported gold, –palladium catalysts

Supported gold, palladium and gold–palladium catalysts have been used to oxidatively dehydrogenate cyclohexane and cyclohexenes to their aromatic counterpart. The supported metal nanoparticles decreased the activation temperature of the dehydrogenation reaction. We found that the order of reactivity was Pd ≥ Au–Pd > Au supported on TiO₂. Attempts were made to lower the reaction temperature whilst retaining high selectivity. The space-time yield of benzene from cyclohexane at 473 K was determined to be 53.7 mol/kg_cat/h rising to 87.3 mol/kg_cat/h at 673 K for the Pd catalyst. Increasing the temperature in this case improved conversion at a detriment to the benzene selectivity. Oxidative dehydrogenation of cyclohexene over AuPd/TiO₂ or Pd/TiO₂ catalysts was found to be very effective (conversion >99% at 423 K). These results indicate that the first step in the reaction sequence of cyclohexane to cyclohexene is the slowest step. These initial results suggest that in a fixed-bed reactor the oxidative dehydrogenation in the presence of oxygen, palladium and gold–palladium catalysts are readily able to surpass current literature examples and with further modification should yield even higher performance.     

Porometry, porosimetry, image analysis and void network modelling in the study of the pore-level properties of filters

We present fundamental and quantitative comparisons between the techniques of porometry (or flow permporometry), porosimetry, image analysis and void network modelling for seven types of filter, chosen to encompass the range of simple to complex void structure. They were metal, cellulose and glass fibre macro- and meso-porous filters of various types. The comparisons allow a general re-appraisal of the limitations of each technique for measuring void structures. Porometry is shown to give unrealistically narrow void size distributions, but the correct filtration characteristic when calibrated. Shielded mercury porosimetry can give the quaternary (sample-level anisotropic) characteristics of the void structure. The first derivative of a mercury porosimetry intrusion curve is shown to underestimate the large number of voids, but this error can be largely corrected by the use of a void network model. The model was also used to simulate the full filtration characteristic of each sample, which agreed with the manufacturer's filtration ratings. The model was validated through its correct a priori simulation of absolute gas permeabilities for track etch, cellulose nitrate and sintered powder filters.     

Interlaminar fracture toughness of woven fabric composite laminates with carbon nanotube/epoxy interleaf films

The Mode I interlaminar fracture behavior of woven carbon fiber/epoxy composite laminates incorporating partially cured carbon nanotube/epoxy composite films has been investigated. Laminates with films containing carbon nanotubes (CNTs) in the as‐received state and functionalized with polyamidoamine were evaluated, as well as laminates with neat epoxy films. Double‐cantilever beam (DCB) specimens were used to measure G_Ic, the critical strain energy release rate (fracture toughness) versus crack length. Post‐fracture microscopic inspection of the fracture surfaces was performed. Results show that initial fracture toughness was improved with the amino‐functionalized CNT/epoxy interleaf films, but the important factor appears to be the polyamidoamine functionalization, not the CNTs. The initial fracture toughness remained relatively unaffected with the incorporation of neat epoxy and as‐received CNT/epoxy interleaf films. Plateau fracture toughness was unchanged with the use of functionalized CNT/epoxy interleaf films, and was reduced with the use of neat epoxy and as‐received CNT/epoxy interleaf films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Identification and Optimization of 4‐Anilinoquinolines as Inhibitors of Cyclin G Associated Kinase

4‐Anilinoquinolines were identified as potent and narrow‐spectrum inhibitors of the cyclin G associated kinase (GAK), an important regulator of viral and bacterial entry into host cells. Optimization of the 4‐anilino group and the 6,7‐quinoline substituents produced GAK inhibitors with nanomolar activity, over 50 000‐fold selectivity relative to other members of the numb‐associated kinase (NAK) subfamily, and a compound (6,7‐dimethoxy‐N‐(3,4,5‐trimethoxyphenyl)quinolin‐4‐amine; 49 ) with a narrow‐spectrum kinome profile. These compounds may be useful tools to explore the therapeutic potential of GAK in prevention of a broad range of infectious and systemic diseases.     

High solids concentration agitation for minerals process intensification

By using mixing intensification involving high solids concentration as a means to achieve process intensification for the mineral process industry is discussed here. Improving agitator energy efficiency is essential for operating at high solids concentrations. It is shown that improved agitator energy efficiency can be achieved by removing baffles and using higher power number impellers at high solids loadings. Power consumption (50–80%) reductions were demonstrated in the experiments. It is also suggested that slurry stratification in tanks can be used to boost either solids residence time or slurry mass flow. Basic equations related to solids residence time and solids throughput are presented for guidance toward minerals process intensification. An example on doubling throughput via intensification is presented. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Probing the Positions of TeO Moieties in the Channels of the MoVNbTeO M1 Catalyst: A Density Functional Theory Model Study

Catalysis Letters - With hybrid DFT calculations applied to periodic models of the bulk MoVNbTeO M1 catalyst, we examined how [TeO]2+ species in the hexagonal channels of this material stabilize...     

Exploring the Molecular Interactions of 7,8-Dihydroxyflavone and Its Derivatives with TrkB and VEGFR2 Proteins

7,8-Dihydroxyflavone (7,8-DHF) is a TrkB receptor agonist, and treatment with this flavonoid derivative brings about an enhanced TrkB phosphorylation and promotes downstream cellular signalling. Flavonoids are also known to exert an inhibitory effect on the vascular endothelial growth factor receptor (VEGFR) family of tyrosine kinase receptors. VEGFR2 is one of the important receptors involved in the regulation of vasculogenesis and angiogenesis and has also been implicated to exhibit various neuroprotective roles. Its upregulation and uncontrolled activity is associated with a range of pathological conditions such as age-related macular degeneration and various proliferative disorders. In this study, we investigated molecular interactions of 7,8-DHF and its derivatives with both the TrkB receptor as well as VEGFR2. Using a combination of molecular docking and computational mapping tools involving molecular dynamics approaches we have elucidated additional residues and binding energies involved in 7,8-DHF interactions with the TrkB Ig2 domain and VEGFR2. Our investigations have revealed for the first time that 7,8-DHF has dual biochemical action and its treatment may have divergent effects on the TrkB via its extracellular Ig2 domain and on the VEGFR2 receptor through the intracellular kinase domain. Contrary to its agonistic effects on the TrkB receptor, 7,8-DHF was found to downregulate VEGFR2 phosphorylation both in 661W photoreceptor cells and in retinal tissue.