Application of functionalised carbon nanotubes immobilised into chitosan films in amperometric enzyme biosensors

A new approach for building a bio-conductive interface for enzyme immobilisation is described. This strategy permits very simple preparation of the enzyme biosensor and also reveals direct electron transfer features. A graphite-epoxy resin composite (GrEC) electrode modified with functionalised multi-wall carbon nanotubes (MWCNTs) immobilised by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide together with N-hydroxysuccinimide (EDC–NHS) in a chitosan (Chit) matrix was prepared and characterised by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of hexaammineruthenium (III) chloride. It was then used as a base for glucose oxidase (GOx) immobilisation by the simple method of crosslinking with glutaraldehyde (GA) with bovine serum albumin (BSA) as carrier protein. The resulting mediator-free biosensor was applied to the determination of glucose in amperometric mode at different applied potentials and the mechanism of reaction was also investigated by cyclic voltammetry, with and without dissolved oxygen in solution. Analytical parameters, as well as reproducibility, repeatability and stability were determined. Interferences were assessed using different compounds usually present in natural samples, such as wines, juices or blood, in order to evaluate the selectivity of the developed biosensor. The novel combination of carbon nanotubes immobilised with chitosan crosslinked with EDC–NHS and glucose oxidase immobilised by crosslinking with glutaraldehyde offers an excellent, easy to make biosensor for glucose determination without interferences.     

A Critical Assessment of Experimental Methods for Determining the Dynamic Mechanical Characteristics of Shape Memory Polymers

Experimental study of temperature‐ and frequency‐dependent properties of the commercially available shape memory polymer Tecoflex? EG 72D (TFX) (Lubrizol, USA) using dynamic mechanical analysis (DMA) technique is presented. Temperature scan DMA tests have been carried out in three distinct deformation modes, uniaxial tension, three‐point bending, and simple torsion, using two different testing rigs at different test parameters (frequency, strain amplitude, and heating rate) in temperatures ranging from below to above the glass transition temperature. The influence of different test parameters and some discrepancies in the temperature‐dependent storage and loss moduli (and hence the loss factor) measured by DMA in different deformation modes are discussed.     

An efficient real‐time method of analysis for non‐coherent fault trees

Fault tree analysis is commonly used to assess the reliability of potentially hazardous industrial systems. The type of logic is usually restricted to AND and OR gates, which makes the fault tree structure coherent. In non‐coherent structures not only components' failures but also components' working states contribute to the failure of the system. The qualitative and quantitative analyses of such fault trees can present additional difficulties when compared with the coherent versions. It is shown that the binary decision diagram (BDD) method can overcome some of the difficulties in the analysis of non‐coherent fault trees. This paper presents the conversion process of non‐coherent fault trees to BDDs. A fault tree is converted to a BDD that represents the system structure function (SFBDD). An SFBDD can then be used to quantify the system failure parameters but is not suitable for the qualitative analysis. Established methods, such as the meta‐products BDD method, the zero‐suppressed BDD (ZBDD) method and the labelled BDD (L‐BDD) method, require an additional BDD that contains all prime implicant sets. The process using some of the methods can be time consuming and is not very efficient. In addition, in real‐time applications the conversion process is less important and the requirement is to provide an efficient analysis. Recent uses of the BDD method are for real‐time system prognosis. In such situations as events happen, or failures occur, the prediction of mission success is updated and used in the decision‐making process. Both qualitative and quantitative assessments are required for the decision making. Under these conditions fast processing and small storage requirements are essential. Fast processing is a feature of the BDD method. It would be advantageous if a single BDD structure could be used for both the qualitative and quantitative analyses. Therefore, a new method, the ternary decision diagram (TDD) method, is presented in this paper, where a fault tree is converted to a TDD that allows both qualitative and quantitative analyses and no additional BDDs are required. The efficiency of the four methods is compared using an example fault tree library. Copyright © 2008 John Wiley & Sons, Ltd.     

Learning symmetric causal independence models

Causal independence modelling is a well-known method for reducing the size of probability tables, simplifying the probabilistic inference and explaining the underlying mechanisms in Bayesian networks. Recently, a generalization of the widely-used noisy OR and noisy AND models, causal independence models based on symmetric Boolean functions, was proposed. In this paper, we study the problem of learning the parameters in these models, further referred to as symmetric causal independence models. We present a computationally efficient EM algorithm to learn parameters in symmetric causal independence models, where the computational scheme of the Poisson binomial distribution is used to compute the conditional probabilities in the E-step. We study computational complexity and convergence of the developed algorithm. The presented EM algorithm allows us to assess the practical usefulness of symmetric causal independence models. In the assessment, the models are applied to a classification task; they perform competitively with state-of-the-art classifiers.     

Protein expression and enzymatic activities in normal and soft textured Atlantic salmon (Salmo salar) muscle

Soft textured Atlantic salmon is a sporadic and occasionally very severe problem for the farming and processing industries. The firm and soft fillets examined in this work differed in their gelatinase activities, cross-reactivity with anti-ubiquitin and anti-cathepsin L antibodies, as well as in the in-gel α-chymotryptic peptide maps of electrophoretically isolated myosin heavy chain (MHC) bands. The immunodetections of actin, α-actinin, MHC, and the MALDI TOF MS peptide mass fingerprinting of electrophoretically isolated MHCs only showed minor differences between samples. Other analyses revealed merely individual differences. These results seem to indicate a higher level of gelatinase activation, ubiquitination and cathepsin L cross-reacting material in softer muscle. These results would be consistent with a myopathy, but also with what could be expected in the skeletal muscle of healthy salmonid fish during a normal period of hyperplastic growth.     

The relationship between problem solving and inhibitory control: Cotton-top tamarins ( Saguinus oedipus ) performance on a reversed contingency task.

To explore the relationship between problem solving and inhibitory control, the authors present 4 experiments on cotton-top tamarins (Saguinus oedipus) using a reverse-reward contingency task. In Experiment 1, 1 group of tamarins was given a choice between a small and a large quantity of food. Whichever quantity the tamarins reached for first, they received the alternative. The tamarins consistently picked the larger quantity, thereby receiving the smaller. A 2nd group of tamarins was given the same task, except that if they reached for the larger quantity of food, they received nothing. The tamarins continued to pick the larger quantity, even though this resulted in no food. In addition, most of the tamarins continued to pick the larger quantity even when the food payoff for choosing the smaller quantity was increased (Experiment 2) or when the visual salience of the food was reduced (Experiment 3). Experiment 4 was based on the finding that chimpanzees (Pan troglodytes) that have been trained on the concept of number can solve the reversed contingency task if the food is replaced by Arabic numerals. With the help of a color association, and a higher cost incurred by picking the color associated with 3 food items, the tamarins learned to pick the color associated with... (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving the Safety and Efficiency of Materials Transfer at a Construction Site by Using an Elevator

The aim of this study was to compare materials transfer at a construction site, either by carrying manually or by using an elevator. Data were collected at a construction site by using two methods: continuous automatic collection of data on the use of the elevator, and measuring and observing the transportation of some products when different delivery systems were used. Health and safety risks were at their highest when transporting products manually at construction sites. Risks decrease when vertical (an elevator) and horizontal (a wheeled device) transportation tools are used. A similar improvement as in health and safety risks can be seen in efficiency results: The working time needed with the elevator was 41% of the purely manual handling time. When wheeled devices were used, the transportation time was decreased to 16%. The early use of a permanent elevator succeeded well and its capacity was large enough. The effective use of the elevator and wheeled devices require that pathways are in better condition than normally.     

Utility of Suspended Solid Measurements for Storm-Water Runoff Treatment

In this paper alternative solutions are presented to solve problems associated with the measurement of total suspended solids (TSS) in storm-water runoff. Results revealed that the accuracy of TSS measurement is largely related to sample representativeness, particle size distribution (PSD), sampling pipette position, and sample mixing. In general, when the PSD in the runoff was mostly larger than 75?μm, the most accurate and reproducible results were obtained when samples were collected from a position of mid-depth and midway between the walls of the beaker and the vortex and mixed at speeds in the range of 600–700?rpm. For runoff samples with a PSD smaller than 75?μm, mixing at a higher rpm is not a significant factor. As long as the PSD in the TSS subsample is representative of the original sample, a strong correlation between TSS and suspended solid concentration can be achieved. The results showed that density was largely correlated with the organic content of the particles, and, in general, smaller particles tended to have a lower density. The density results revealed that assuming a single sand size density of 2.6?g/cm3 for storm-water runoff produced a large error in the computation of sediment load and particle settling velocity.     

Dispositional resistance to change: Measurement equivalence and the link to personal values across 17 nations.

The concept of dispositional resistance to change has been introduced in a series of exploratory and confirmatory analyses through which the validity of the Resistance to Change (RTC) Scale has been established (S. Oreg, 2003). However, the vast majority of participants with whom the scale was validated were from the United States. The purpose of the present work was to examine the meaningfulness of the construct and the validity of the scale across nations. Measurement equivalence analyses of data from 17 countries, representing 13 languages and 4 continents, confirmed the cross-national validity of the scale. Equivalent patterns of relationships between personal values and RTC across samples extend the nomological net of the construct and provide further evidence that dispositional resistance to change holds equivalent meanings across nations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Residues of doxycycline and oxytetracycline in eggs after medication via drinking water to laying hens

Doxycycline (DOTC) and oxytetracycline (OTC) were dissolved in drinking water (0.5 g/l) and supplied to laying hens for 7 consecutive days. Eggs laid were collected daily during and after medication, and the antibiotic concentrations in the yolk and albumin were determined by the cup-plate method with Bacillus cereus var. mycoides ATCC 11778. The concentrations of both antibiotics were increased in yolk day by day with the advance in medication, reached peaks 2 days after withdrawal and then declined gradually. Mean peak concentrations in the yolk were 6.70 micrograms/g for DOTC and 1.42 micrograms/g for OTC. Peak concentrations in the albumin occurred in the middle stage of medication, where the mean values were 12.24 micrograms/g for DOTC and 1.03 micrograms/g for OTC. DOTC was detected in albumin until 24 days after withdrawal and for 2 days more in yolk than in albumin. OTC was detected in yolk until 9 days after withdrawal. The depletion period of OTC was shorter for the albumin, where the residue disappeared in all eggs 6 days after withdrawal. In spite of similarities between DOTC and OTC in structure, DOTC was deposited in higher concentrations and lasted for a longer period in eggs. This characteristic was considered due to its greater lipophilicity, closely correlated with oral absorption and tissue penetration.