Aflatoxin species: their health effects and determination methods in different foodstuffs

Carcinogenic and mutagenic properties of aflatoxin species are known in literature. Their intake over a long time period might be health-dangerous for human even at trace levels. It is well known that different foodstuffs can be contaminated by aflatoxin species through growing and storage. Due to the serious health effects, sensitive determination of aflatoxin species in any matrices related with the human being is very crucial at trace levels. In literature, there are sensitive techniques to analyze the different samples for the contents of their aflatoxin species. Each technique has some advantages and disadvantages over the other techniques. This review aims to summarize the different health effects of aflatoxin species, development of analytical techniques and applications of developed techniques in a variety of matrices.      

Dynamics of TiO2-based photoelectrochemical cell

The present work reports the effect of light on the open-circuit voltage of a photoelectrochemical cell (PEC) formed of TiO₂ photoanode, Pt cathode and Na₂SO₄ (0.35 M) aqueous solution as electrolyte. The studies included the measurements of the electromotive force (EMF) during the light-off and light-on cycles for the PEC involving photoanode that was made of both oxidised and reduced TiO₂ thin films. These specimens were formed by oxidation of the titanium metal at high and low oxygen activities. This was achieved by the imposition of the gas phase of two different compositions, including air, p(O₂) = 21 kPa, and the hydrogen–water vapour mixture, p(O₂) = 10^-10p({\rm O}_2) = 10^{-10} Pa, at 1,123 K and subsequent cooling to room temperature. The determined data indicate that the PEC formed of the oxidised specimen exhibits larger EMF and a substantially better stability in time. It is, therefore, concluded that the TiO₂ obtained in air exhibits superior performance-related properties compared to the reduced specimen. The obtained experimental EMF data are considered in terms of the effect of light on the reactivity of TiO₂ with oxygen and water and the related charge transfer.     

Toward sustainable energy: photocatalysis of Cr-doped TiO<Subscript>2</Subscript>: 2. effect of defect disorder

The present chain of five papers considers the concept of solar-to-chemical energy conversion using TiO₂-based semiconductors. The series reports the effect of chromium on the key performance-related properties of polycrystalline TiO₂ (rutile), including electronic structure, photocatalytic activity, intrinsic defect disorder, electrochemical coupling and surface versus bulk properties. In this work, we show that the effect of chromium on photocatalytic performance of TiO₂ depends on its elemental content and the related defect disorder that is determined by oxygen activity in the oxide lattice. At high oxygen activity, chromium leads to enhanced photocatalytic performance only for dilute solid solutions (up to 0.04–0.043 at.% Cr). Higher chromium content results in a decrease of photocatalytic activity below that for pure TiO₂, despite the observed substantial decrease of the band gap. The photocatalytic performance of Cr-doped TiO₂ annealed in reducing conditions is low within the entire studied range of compositions. The obtained results led to derivation of a theoretical model representing the mechanism of the light-induced reactivity of TiO₂ with water and the related charge transfer. The photocatalytic performance is considered in terms of a competitive effect of several key performance-related properties. The performance is predominantly influenced by the concentration of titanium vacancies acting as reactive surface sites related to anodic charge transfer.

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Verification of a model to predict the influence of particle inertia and gravity on a decaying turbulent particle-laden flow

In an earlier publication some of the authors presented a theoretical model for the calculation of the influence of particle inertia and gravity on the turbulence in a stationary particle-laden flow. In the present publication the model is extended for application to a decaying suspension. Also a comparison is given between predictions made with the model and experimental data (own data and data reported in the literature) on a decaying turbulent flow with particles in a water tunnel or in a wind tunnel. For most of the experiments a prediction with reasonable accuracy and an interpretation is possible by means of the model.