8 research outputs found
The Aflatoxin QuicktestTMâA Practical Tool for Ensuring Safety in Agricultural Produce
Contamination of corn, peanuts, milk and dairy products with aflatoxins is a worldwide problem, particularly in subtropical regions where the climatic conditions are ideal for the growth of Aspergillus flavus, the fungi that produces these toxins. Developing countries have major difficulties in marketing these products abroad due to the stringent international regulations concerning this carcinogenic toxin. Adding to the problem is the analytical cost involved in monitoring the produce, which require sophisticated instrumentation and qualified personnel, neither of which are available for field testing. The development of a rapid Aflatoxin Quicktest⢠provides an effective, reliable and cheaper option for screening levels of aflatoxin above the regulatory thresholds in such produce. The test consists of a lateral flow device (LFD) coated with antibodies specific to aflatoxin B1, although it detects other aflatoxins (i.e. G and M) with high cross-reactivity. Its high sensitivity allows analysis of these toxins in the range 2â40 Οg/kg of sample in 15 minutes, plus the time for extraction, which varies among different products. Quantification of the test results is done using a Quick Reader, by comparing the readings of individual tests against a standard curve of the analytes in the same manner as it is done with any other analytical equipment. A validation study was carried out using peanuts from Australia and peanuts and corn from Timor-Leste to assess the performance of the Aflatoxin Quicktestâ˘. Results obtained with the LFD showed a good correlation with the standard analytical measurements by HPLC-fluorescence (r2 above 0.90 for all cases), indicating the Aflatoxin Quicktest⢠is capable of measuring levels of aflatoxins accurately and reliably. Given their ease of use, low cost and fast processing time, the Aflatoxin Quicktest⢠can be used for screening agricultural produce in countries that cannot afford the costly alternative of using specialised personnel and equipment
Probabilistic risk assessment of diuron and prometryn in the Gwydir River catchment, Australia, with the input of a novel bioassay based on algal growth
John Clare and place
This chapter tackles issues of place in the self-presentation and critical reception of John Clare, and pursues it across a number of axes. The argument centres on the placing of Clare both socio-economically and ânaturallyâ, and limitations exerted upon perceptions of his work. Interrogating criticism this chapter finds a pervasive awkwardness especially in relation to issues of class and labour. It assesses the contemporary âplacingâ of Clare, and seemingly unavoidable insensitivities to labour and poverty in the history industry, place-naming, and polemical ecocriticism. It assesses the ways Clare represents place â in poverty, in buildings, in nature â and, drawing on Michel de Certeau, considers the tactics Clare uses to negotiate his place. It pursues trajectories to âun-placeâ Clare: the flight of fame in Clareâs response to Byron; and the flight of an early poem in songbooks and beyond, across the nineteenth century
A Simple Method to Estimate Entropy and Free Energy of Atmospheric Gases from Their Action
A convenient practical model for accurately estimating the total entropy (ΣSi) of atmospheric gases based on physical action is proposed. This realistic approach is fully consistent with statistical mechanics, but reinterprets its partition functions as measures of translational, rotational, and vibrational action or quantum states, to estimate the entropy. With all kinds of molecular action expressed as logarithmic functions, the total heat required for warming a chemical system from 0 K (ΣSiT) to a given temperature and pressure can be computed, yielding results identical with published experimental third law values of entropy. All thermodynamic properties of gases including entropy, enthalpy, Gibbs energy, and Helmholtz energy are directly estimated using simple algorithms based on simple molecular and physical properties, without resource to tables of standard values; both free energies are measures of quantum field states and of minimal statistical degeneracy, decreasing with temperature and declining density. We propose that this more realistic approach has heuristic value for thermodynamic computation of atmospheric profiles, based on steady state heat flows equilibrating with gravity. Potentially, this application of an action principle can provide better understanding of emergent properties of many natural or evolving complex systems, including modelling of predictions for global warming
Computer-Aided Molecular Modeling Study on Antibody Recognition of Small Molecules: An Immunoassay for Triazine Herbicides
Most immunoassays for determination of small molecules
are still
designed on the basis of the âtrial and errorâ method,
due to the lack of understanding of antibody recognition. In the present
study, we developed a heterologous indirect competitive enzyme-linked
immunosorbent assay for determination of triazine herbicides, with
limits of detection for 11 triazines ranging from 0.05 to 29.4 Îźg/L.
Mechanisms of the antigenâantibody interaction were studied
by computer-aided molecular modeling (CAMM)-based quantitative structureâactivity
relationship analyses. Co-effects of the analytesâ substructural
hydrophobic, electrostatic, and steric fields on antibody recognition
were further revealed. Hydrophobicity of the antigens was demonstrated
to have the most important impact. Even less exposed substituents
provided hydrophobic force to the antigenâantibody interaction.
Dislocated orientation of analyte functional groups could lead to
steric hindrance and hydrophobic misleading of antibody recognition.
This may happen even when the antigens contained the same substituent
as the hapten. Frontier orbital energies also affect the reaction
significantly. This study highlights of the power of CAMM-based analyses,
providing insights into antibody recognition of small molecules