Simultaneous enzyme immunoassay for the screening of aflatoxin B1 and ochratoxin A in chili samples

Membrane-based immunoassay has been developed for simultaneous estimation of aflatoxin B₁ (AFB₁) and ochratoxin A (OA) in chili samples. The combined estimation of both the mycotoxins is more economical in respect of time, work and materials than two separate assays. The method uses a low cost test device consisting of a membrane with immobilized anti-AFB₁ and anti-OA antibodies and a filter paper attached to a polyethylene card below the membrane. It allows direct analysis of sample extracts containing substantial amount (40%) of methanol. This permits the use of two-fold diluted sample extracts resulting in minimum dilution error. The limit of quantitation obtained was 2 and 10 μg kg⁻¹ for AFB₁ and OA, respectively. The tolerance of 40% methanol was found to be due to the application of small size (0.8 mm diameter) spots on membranes, as the tolerance decreases to 20% with gradual increase in spot size. The combined method is capable of producing acceptable results to analyze AFB₁ and OA in chili with accuracy and precision. The AFB₁ and OA values obtained for spiked and naturally contaminated chili samples by the simultaneous method were in good correlation with those measured by individual ELISA. The method offers a simple, rapid and cost-effective screening tool to meet the requirements of the rapidly evolving EU legislation.     

The onset of coulomb explosions in polyatomic molecules

With the development of high intensity femtosecond lasers, the ionisation and dissociation dynamics of molecules has become an area of considerable interest. Using the technique of femtosecond laser mass spectrometry (FLMS), the molecules carbon disulphide, pyrimidine, toluene, cyclohexanone and benzaldehyde are studied with pulse widths of 50 fs in the near infrared (IR) wavelength region (790 nm). Results are presented and contrasted for laser beam intensities around 10(15) and 10(16) W cm(-2). For the lower intensities, the mass spectra yield dominant singly charged parent ions. Additionally, the appearance of doubly charged parent ions is evident for carbon disulphide, toluene and benzaldehyde with envelopes of doubly charged satellite species existing in these local regions. Carbon disulphide also reveals a small triply charged component. Such atomic-like features are thought to be a strong fingerprint of FLMS at these intensities. However, upon increasing the laser intensity to approximately 10(16) W cm(-2), parent ion dominance decreases and the appearance of multiply charged atomic species occurs, particularly carbon. This phenomenon has been attributed to Coulomb explosions in which the fast absorption of many photons may produce transient highly ionised parent species which can subsequently blow apart. Copyright 1999 John Wiley & Sons, Ltd.     

Uniform molecular analysis using femtosecond laser mass spectrometry

The potential of femtosecond laser time-of-flight mass spectrometry (FLMS) for uniform quantitative analysis of molecules has been investigated. Various samples of molecular gases and vapours have been studied, using ultra-fast ( approximately 50 fs) laser pulses with very high intensity (up to 1.6 x 10(16) Wcm(-2)) for non-resonant multiphoton ionisation/tunnel ionisation. Some of these molecules have high ionisation potentials, requiring up to ten photons for non-resonant ionisation. The relative sensitivity factors (RSF) have been determined as a function of the laser intensity and it has been demonstrated that for molecules with very different masses and ionisation potentials, uniform ionisation has been achieved at the highest laser intensities. Quantitative laser mass spectrometry of molecules is therefore a distinct possibility. Copyright 1999 John Wiley & Sons, Ltd.     

Interpreting early land management through compound specific stable isotope analyses of archaeological soils

Compound specific stable isotope analyses of managed soils using isotope ratio mass spectrometry have been undertaken as a means of determining early land use practices. delta (15)N amino acid signals demonstrate differences between manured grassland, unmanured grassland and continuous cereal cultivation under long-term experimental land use control conditions, with delta (15)N in hydrophobic amino acids providing the most distinctive signals. Analysis of early modern/medieval and of Bronze age anthropogenic soils from Orkney demonstrates that such signals are retained in archaeological contexts. delta (13)C analyses of n- alkanoic acid components of the fossil, Bronze Age, anthropogenic soils suggest a major terrestrial input to these soils, with uniform composition of formation materials. Surficial soils demonstrate the assimilation of isotopically lighter carbon, providing a means of assessing the mobility of the n- alkanoic acids within soils and sediments. Copyright 1999 John Wiley & Sons, Ltd.     

Realization of an Asymmetric Non-Aqueous Redox Flow Battery through Molecular Design to Minimize Active Species Crossover and Decomposition

This communication presents a mechanism-based approach to identify organic electrolytes for non-aqueous redox flow batteries (RFBs). Symmetrical flow cell cycling of a pyridinium anolyte and a cyclopropenium catholyte resulted in extensive capacity fade due to competing decomposition of the pyridinium species. Characterization of this decomposition pathway enabled the rational design of next-generation anolyte/catholyte pairs with dramatically enhanced cycling performance. Three factors were identified as critical for slowing capacity fade: (1) separating the anolyte–catholyte in an asymmetric flow cell using an anion exchange membrane (AEM); (2) moving from monomeric to oligomeric electrolytes to limit crossover through the AEM; and (3) removing the basic carbonyl moiety from the anolyte to slow the protonation-induced decomposition pathway. Ultimately, these modifications led to a novel anolyte–catholyte pair that can be cycled in an AEM-separated asymmetric RFB for 96 h with >95 % capacity retention at an open circuit voltage of 1.57 V.     

Novel In-Situ NanoEmulGel (NEG) of Azithromycin with Eugenol for the Treatment of Periodontitis: Formulation Development and Characterization

Journal of Cluster Science - The aim of present study was to develop and evaluate novel in situ nanoemulgel (NEG) of azithromycin (AZM) with eugenol for intra-pocket drug delivery for the treatment...     

Accurate potential energy curves for Tl+–Rg (Rg=He–Rn): spectroscopy and transport coefficients

High-quality ab initio potential energy curves are presented for the Tl⁺–Rg series (Rg=He–Rn). Calculations are performed at the CCSD(T) level of theory, employing aug-cc-pV5Z quality basis sets, with ‘small core' relativistic effective core potentials being used for Tl⁺ and Kr–Rn. The curves are shown to be in excellent agreement with experimental mobility data for the systems Tl⁺–Rg (Rg=He–Xe), and generally excellent agreement is also obtained with longitudinal diffusion data. An exception to the latter is Tl⁺ in He, which is attributed to the experimental data not being obtained under steady state conditions. Spectroscopic information is also presented for the titular species, derived from potential energy curves, and the results are compared with previous potentials inferred from the ion transport data.     

Durandal: fast exact clustering of protein decoys

In protein folding, clustering is commonly used as one way to identify the best decoy produced. Initializing the pairwise distance matrix for a large decoy set is computationally expensive. We have proposed a fast method that works even on large decoy sets. This method is implemented in a software called Durandal. Durandal has been shown to be consistently faster than other software performing fast exact clustering. In some cases, Durandal can even outperform the speed of an approximate method. Durandal uses the triangular inequality to accelerate exact clustering, without compromising the distance function. Recently, we have further enhanced the performance of Durandal by incorporating a Quaternion-based characteristic polynomial method that has increased the speed of Durandal between 13% and 27% compared with the previous version. Durandal source code is available under the GNU General Public License at http://www.riken.jp/zhangiru/software/durandal_released_qcp.tgz. Alternatively, a compiled version of Durandal is also distributed with the nightly builds of the Phenix (http://www.phenix-online.org/) crystallographic software suite (Adams et al., Acta Crystallogr Sect D 2010, 66, 213).     

Size-dependent Creep Master Curve of Individual Electrospun Polymer Nanofibers

Experimental Mechanics - While there is great interest in polymer nanofibers due to their high strength, methods to measure their time-temperature superposition (TTS) curves are lacking. The...