Bioanalytical and chemical assessment of the disinfection by-product formation potential: Role of organic matter

Disinfection by-products (DBP) formed from natural organic matter and disinfectants like chlorine and chloramine may cause adverse health effects. Here, we evaluate how the quantity and quality of natural organic matter and other precursors influence the formation of DBPs during chlorination and chloramination using a comprehensive approach including chemical analysis of regulated and emerging DBPs, total organic halogen quantification, organic matter characterisation and bioanalytical tools. In vitro bioassays allow us to assess the hazard potential of DBPs early in the chain of cellular events, when the DBPs react with their molecular target(s) and activate stress response and defence mechanisms. Given the reactive properties of known DBPs, a suite of bioassays targeting reactive modes of toxic action including genotoxicity and sensitive early warning endpoints such as protein damage and oxidative stress were evaluated in addition to cytotoxicity. Coagulated surface water was collected from three different drinking water treatment plants, along with reverse osmosis permeate from a desalination plant, and DBP formation potential was assessed after chlorination and chloramination. While effects were low or below the limit of detection before disinfection, the observed effects and DBP levels increased after disinfection and were generally higher after chlorination than after chloramination, indicating that chlorination forms higher concentrations of DBPs or more potent DBPs in the studied waters. Bacterial cytotoxicity, assessed using the bioluminescence inhibition assay, and induction of the oxidative stress response were the most sensitive endpoints, followed by genotoxicity. Source waters with higher dissolved organic carbon levels induced increased DBP formation and caused greater effects in the endpoints related to DNA damage repair, glutathione conjugation/protein damage and the Nrf2 oxidative stress response pathway after disinfection. Fractionation studies indicated that all molecular weight fractions of organic carbon contributed to the DBP formation potential, with the humic rich fractions forming the greatest amount of DBPs, while the low molecular weight fractions formed more brominated DBPs due to the high bromide to organic carbon ratio. The presence of higher bromide concentrations also led to a higher fraction of brominated DBPs as well as proportionally higher effects. This study demonstrates how a suite of analytical and bioanalytical tools can be used to effectively characterise the precursors and formation potential of DBPs.     

Hyperbranched polymers containing oxazoline monomers and succinic anhydride: Applications in fast drying,low solvent coating formulations

Melt-polycondensation of succinic acid anhydride with oxazoline-based diol monomers gave hyperbranched polymers with carboxylicacids terminal groups. ¹H NMR and quantitative ¹³C NMR spectroscopy coupled with DEPT-135 ¹³C NMR experiment showed high degrees of branching (over 60%). Esterification of the acid end groups by addition of citronellol at 160 °C produced novel white spirit soluble resins which were characterized by Fourier transform-infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Blends of the new hyperbranched materials with commercial alkyd resins resulted in a dramatic, concentration dependent drop in viscosity. Solvent-borne coatings were formulated containing the hyperbranched polymers. Dynamic mechanical analysis studies revealed that the air drying rates of the new coating systems were enhanced compared with identical formulations containing only commercial alkyd resins.     

Facilitating a benign attentional bias reduces negative thought intrusions.

The causal role of biased attention in worry was investigated in an experiment in which high worriers were assigned either to a condition requiring attention to nonthreatening words and text while ignoring worry-related material or to a mixed-attention control condition. The former procedure led to fewer negative thought intrusions in a worry test (as rated by both participants and an assessor) than did the control condition. These findings suggest that attentional bias plays a causal role in worry and that its modification can reduce excessive worry. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optical Spectroscopy of Inorganic Solids

Abstract

The inhomogeneity of thin films of ZrO₂ and TiO₂ was reduced by ion beam bombardment with mixed argon and oxygen as a working gas during deposition. The inhomogeneities of the films were calculated from transmission monitoring curves. The optimum ion beam voltage and ion beam current density are 900 V and 12 μA cm^?2 for TiO₂ film.     

Evolution of supramolecular healable composites: a minireview

Efforts to further extend the range of applications of polymer based materials have resulted in the recent production of healable polymers that can regain their strength after damage. Within this field of healable materials, supramolecular polymers have been subject to extensive investigation. By virtue of their reversible non‐covalent interactions, cracks and fractures in such polymers can be readily and repeatedly healed in order to regain key physical properties. However, many supramolecular polymers are relatively weak and elastomeric in nature, which renders them unsuitable for high strength structural applications. To overcome these deficiencies, preliminary studies have shown that it is possible to reinforce supramolecular polymers with microscale and nanoscale fillers to afford composites that are not only stronger and stiffer compared with the polymers alone but also retain their healing abilities. In this minireview we discuss the evolution of these supramolecular composites and their advantages over more conventional, covalent polymeric materials. © 2014 Society of Chemical Industry     

Energy cultures: A framework for understanding energy behaviours

Achieving a ‘step-change’ in energy efficiency behaviours will require enhanced knowledge of behavioural drivers, and translation of this knowledge into successful intervention programmes. The ‘Energy Cultures’ conceptual framework aims to assist in understanding the factors that influence energy consumption behaviour, and to help identify opportunities for behaviour change. Building on a history of attempts to offer multi-disciplinary integrating models of energy behaviour, we take a culture-based approach to behaviour, while drawing also from lifestyles and systems thinking. The framework provides a structure for addressing the problem of multiple interpretations of ‘behaviour’ by suggesting that it is influenced by the interactions between cognitive norms, energy practices and material culture.     

The utility of intraindividual variability in selective attention tasks as an early marker for Alzheimer’s disease.

This study explored differences in intraindividual variability in 3 attention tasks across a large sample of healthy older adults and individuals with very mild dementia of the Alzheimer’s type (DAT). Three groups of participants (healthy young adults, healthy older adults, very mild DAT) were administered 3 experimental measures of attentional selection and switching (Stroop, Simon, task switching). The results indicated that a measure of intraindividual variability, coefficient of variation (CoV; SD/M), increased across age and early stage DAT. The CoV in Stroop discriminated the performance of ε4 carriers from noncarriers in healthy older controls and the CoV in task switching was correlated with cerebrospinal fluid (CSF) biomarkers predictive of DAT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling of an Unbonded CFRP Strap Shear Retrofitting System for Reinforced Concrete Beams

A retrofitting technique has been developed that uses carbon fiber-reinforced polymer (CFRP) straps to increase the shear capacity of reinforced concrete beams. The vertical straps are not bonded to the beam but are instead anchored against the beam, which makes this technique potentially more effective than bonded FRP retrofitting techniques. However, it also means that models for bonded FRPs are not appropriate for use with the straps. Instead, a model based on a shear friction approach has been developed where the strain in the straps is calculated based on a term that accounts for the effects of prestress and additional strain in the strap due to shear crack opening. The model can either consider the shear reinforcement to be smeared along the length of the beam or discrete elements. The “smeared” model was checked against an experimental database consisting of rectangular, T-, and deep beams, both in terms of predicted capacity and predicted strain in the straps. Overall the smeared model predicted the capacity of the specimens and, with some adjustments, the strains quite accurately. There were, however, cases when it was more appropriate to use the “discrete” model such as when the transverse reinforcement ratio was low or when the transverse reinforcement spacing was high. Further experimental data are required to fully validate the models and to determine appropriate limits on the use of the smeared model and the discrete model. However, the initial results are promising.