Development of redox‐mediated oxysilane sol–gel biosensors on carbon‐film electrode substrates

Three types of carbon‐film electrodes, made from electrical resistors with 1.5‐, 15‐, and 140‐Ω nominal resistances, were used to develop redox‐mediated sol–gel biosensors, and the results were compared with those from previously investigated 2‐Ω carbon‐film electrodes. Two different redox mediators, copper hexacyanoferrate and poly(neutral red), were deposited onto the carbon‐film electrodes, with the latter showing good electrochemical properties for electroanalytical applications, which were best on electrodes made from 15‐Ω carbon‐film resistors. It was not possible to deposit mediator film on the carbon‐film resistor electrodes of 140‐Ω nominal resistance. Glucose oxidase was immobilized on poly(neutral red) modified electrodes with sol–gel encapsulation from a mixture of 3‐glycidoxypropyltrimethoxysilane and methyltrimethoxysilane precursors at a volume ratio of 2 : 1. The best sensor electrochemical properties and response to glucose in model solution were found with electrodes constructed from 15‐Ω resistors, although the stability under the same conditions was better in the biosensors constructed with 2‐Ω nominal resistance electrodes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

On Pseudo-Elastic Models for Stress Softening in Elastomeric Balloons

The phenomenon of stress softening observed in the cyclic inflation of spherical balloons or membranes is quantitatively and qualitatively examined. A new measure of the stress softening extent is proposed which correctly captures the main feature of this phenomenon. This measure of the stress softening is related to the relevant response functions in the constitutive models proposed in the literature to describe this effect. Using these relationships, the predictive capability of the theoretical models is examined. It is shown that only those theoretical models which admit a non-monotone character of the stress softening can properly describe this phenomenon.     

Electrochemical impedance studies of chitosan-modified electrodes for application in electrochemical sensors and biosensors

Graphite-epoxy resin composite (GrEC) electrodes were modified with chitosan (Chit) films and characterised using electrochemical impedance spectroscopy (EIS). Several film modifications were made using different crosslinking agents: glutaraldehyde (GA), glyoxal (GO), epichlorohydrin (ECH) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) together with N-hydroxysuccinimide (NHS) and the characteristics of each of them evaluated in the presence of model electroactive compounds potassium hexacyanoferrate(III) and hexaammineruthenium(III) chloride. Immobilisation of functionalised carbon nanotubes into chitosan matrices (Chit-CNT) using the same crosslinking agents was also investigated. The impedance of the electrode with the best performance (GrEC/Chit-CNT/EDC-NHS) was characterised as a sensor for dipyrone and hydroquinone and for a glucose biosensor by immobilisation of glucose oxidase (GOx) on top of Chit-CNT using GA. Modelling and equivalent circuit analysis was carried out, with emphasis on diffusion characteristics and the significant features of the spectra are discussed.     

Defensive Secretion Components of the Host Parastizopus armaticeps as Kairomones for the Cleptoparasite Eremostibes opacus

The subsocial tenebrionid Parastizopus armaticeps Pér. is parasitized by the closely related Eremostibes opacus Koch (Coleoptera: Tenebrionidae). We found that the pygidial defensive secretions of both species are similar and contain a mixture of 1,4-benzoquinones, 1-alkenes, and monoterpene hydrocarbons. The 1-alkenes are dominated by 1-undecene, with admixtures of 1-tridecene in both species and 1-pentadecene in P. armaticeps only. Methyl- and ethyl-1,4-benzoquinone are the major quinones of the secretions of both species. The monoterpene fractions consist of (−)-α-pinene, (−)-camphene, sabinene, (−)-β-pinene, and (−)-limonene. Volatiles trapped with Porapak Q at the entrance to the breeding burrows of P. armaticeps were identified as components of the defensive secretion. However, in contrast to the secretion, the 1,4-benzoquinones were almost completely absent in the volatiles. Bioassays investigating attraction showed that the cleptoparasite E. opacus was drawn to the monoterpene hydrocarbons, produced by P. armaticeps, and deterred by the 1,4-benzoquinones. The 1-alkenes had no effect. Among the monoterpenes, only (−)-camphene was attractive to E. opacus. This is one of the rare cases of chemical exploitation of defensive allomones, and the first based on odor homology. We have drawn an evolutionary scenario including various functional changes in the defensive secretion compounds, leading to the kairomonal exploitation.     

A Petri Net Approach to Fault Verification in Phased Mission Systems using the Standard Deviation Technique

Health management systems are now standard aspects of complex systems. They monitor the behaviour of components and sub‐systems and in the event of unexpected system behaviour diagnose faults that have occurred. Although this process should reduce system downtime, it is known that health management systems can generate false faults that do not represent the actual state of the system and cause resources to be wasted. The authors propose a process to address this issue in which Petri nets (PNs) are used to model complex systems. Faults reported on the system are simulated in the PN model to predict the resultant system behaviour. This behaviour is then compared to that from the actual system. Using the standard deviation technique, the similarity of the system variables is assessed and the validity of the fault determined. The process has been automated and is tested through application to an experimental rig representing an aircraft fuel system. The success of the process to verify genuine faults and identify false faults in a multi‐phase mission is demonstrated. A technique is also presented that is specific to tank leaks where depending on the location and size of the leak, the resulting symptoms will vary. Copyright © 2012 John Wiley & Sons, Ltd.     

Chitosan–Alginate Microcapsules Provide Gastric Protection and Intestinal Release of ICAM‐1‐Targeting Nanocarriers,Enabling GI Targeting In Vivo

When administered intravenously, active targeting of drug nanocarriers (NCs) improves biodistribution and endocytosis. Targeting may also improve NC oral delivery to treat gastrointestinal (GI) pathologies or for systemic absorption. However, GI instability of targeting moieties compromises this strategy. This study explores whether encapsulation of antibody‐coated NCs in microcapsules would protect against gastric degradation, providing NC release and targeting in intestinal conditions. Nanoparticles coated with antibodies against intercellular adhesion molecule‐1 (anti‐ICAM) or nonspecific immunoglobulin G (IgG) are encapsulated in chitosan (shell) ‐ alginate (core) microcapsules. Encapsulation efficiency is >95% and NC relase from microcapsules in storage is <10%. There is minimal NC release at gastric pH (<10%) and burst release at intestinal pH (75%–85%). Encapsulated NCs afford increased protection against degradation (threefold to fourfold) and increased cell targeting (8–20‐fold) after release versus the nonencapsulated NCs. Mouse oral gavage shows that microencapsulation provides 38%–65% greater protection of anti‐ICAM NCs in the GI tract, 40% lower gastric retention, and fourfold to ninefold enhanced intestinal biodistribution versus nonencapsulated NCs. Therefore, microencapsulation of antibody‐targeted NCs may enable active targeting strategies to be effective in the context of oral drug delivery.     

Quality-focused resource allocation for resilient 5G network

Photonic Network Communications - The upcoming 5G cellular wireless network brings new challenges and problematic issues in providing services with different quality of service (QoS) requirements...     

Proteolytic activities of ventral muscle and intestinal content of North Sea herring (Clupea harengus) with full and emptied stomachs

The aim of the work was to examine the effect of allowing herring (Clupea harengus) to empty the stomachs prior to being taken on board the fishing vessels, on the proteolytic activities in extracts of ventral muscle and of intestinal content. The proteolytic activities were examined by gelatin zymography and by incubating the extracts with isolated myosin heavy chain (MHC) protein. Extracts from herring with full stomachs showed strong gelatinolytic and MHC degrading activities particularly in extracts from intestinal contents. Extracts from fish that had been allowed to empty their digestive system for 19 h had reduced activities, which was most noticeable in the ventral muscle extracts. The activities from the ventral muscle did not originate endogenously post-mortem, as shown by the fact that ice storage for 24 h of isolated ventral muscle did not display the activities, while ventral muscle extract from ice-stored whole fish for 24 h did.     

High resolution two-dimensional electrophoresis as a tool to differentiate wild from farmed cod (Gadus morhua) and to assess the protein composition of klipfish

Tris and CHAPS–urea extracts from wild and farmed cod muscle and from rehydrated cod klipfish fillets were analyzed by one (1DE) and two-dimensional electrophoresis (2DE). 2DE maps of tris extracts from farmed cod differed from the wild in a series of spots of Mw 35 and 45 kDa. The CHAPS–urea extracts from farmed cod had a several spots of Mw between 100 and 45 kDa, which were hardly detectable in wild cod and very prominent in klipfish. Klipfish was clearly different from the other samples: the myosin heavy chain was hardly detectable in these samples, and the tris extracts contained fewer, and the CHAPS–urea more spots than the corresponding extracts from the raw muscles. Further identification of these potentially diagnostic spots will make it easier the differentiation of farmed from wild cod and the evaluation of klipfish processing on the protein content of the product.