High amounts of free aromatic amino acids in the protein-like fluorescence of water-dissolved organic matter

Fluorescence spectroscopy is widely used to study water pollution. The fluorescence of water natural organic matter can be classified into two groups: the protein-like fluorescence originating from aromatic amino acids and the humic fluorescence originating from humic substances. Actually, the precise molecular origin of the protein-like fluorescence is unknown because this fluorescence may be caused by either free amino acids, peptides or proteins. Therefore, we studied the molecular origin of the protein-like fluorescence of Suwannee River natural organic matter and fractions A, B and C + D obtained by size exclusion chromatography/polyacrylamide gel electrophoresis. Fractions were analyzed by reversed-phase high-performance liquid chromatography. The electrophoretic mobilities of fractions varied in the order C + D > B > A and the molecular size in the opposite order. Our results show that the protein-like fluorescence is almost exclusively located in high molecular size fraction A and medium molecular size fraction B. Retention times and fluorescence emission spectra of authentic free aromatic amino acids tyrosine and tryptophan were identical with the retention times and emission spectra of several chromatographic peaks of fractions A and B. More than 50 % of the protein-like fluorescence is due to free aromatic amino acids incorporated in water natural organic matter.     

Rates of spread of <Emphasis Type="Italic">Rosa rugosa</Emphasis> (Japanese Rose) determined by GIS on a coastal sand-dune system in Northwest England

The invasive non-native shrub Rosa rugosa (Japanese Rose) is well-established in many northwest European countries where, especially on coastal sand-dunes, it forms large dominant stands with adverse effects on semi-natural vegetation and biota of high conservation status. Its recent increase in England’s largest dune system on the Sefton Coast in north Merseyside led to an investigation into its rate of spread. Using digitised aerial photographs and GIS methodology, sample patches of old-established R. rugosa were found to have grown in area by an average of 22 % per annum between 1989 and 2013. This rate of increase is comparable to that found in Denmark and higher than reported for several other woody plants in coastal dunes. In the absence of management, R. rugosa could soon dominate large areas on the Sefton Coast, with serious consequences for amenity and the nature conservation interest of the dune system.     

Essential and toxic elements in infant foods from Spain, UK, China and USA

Spanish gluten-free rice, cereals with gluten, and pureed baby foods were analysed for essential macro-elements (Ca and Na), essential trace elements (Fe, Cu, Zn, Mn, Se, Cr, Co and Ni) and non-essential trace elements (As, Pb, Cd and Hg) using ICP-MS and AAS. Baby cereals were an excellent source of most of the essential elements (Ca, Fe, Cu, Mn and Zn). Sodium content was high in pureed foods to improve their flavour; fish products were also rich in Se. USA pure baby rice samples had the highest contents of all studied essential elements, showing a different nutrient pattern compared to those of other countries. Mineral fortification was not always properly stated in the labelling of infant foods. Complementary infant foods may also contain significant amounts of contaminants. The contents of Hg and Cd were low enough to guarantee the safety of these infant foods. However, it will be necessary to identify the source and reduce the levels of Pb, Cr and As in Spanish foods. Pure baby rice samples contained too much: Pb in Spain; As in UK; As, Cr and Ni in USA; and Cr and Cd in China.     

Compositional changes of crude oil SARA fractions due to biodegradation and adsorption on colloidal support such as clays using Iatroscan

The compositional changes of saturates, aromatics, resins and asphaltenes (SARA) fractions in aqueous clay/oil microcosm experiments with a hydrocarbon-degrading microorganism community were analysed using Iatroscan. The clay mineral samples used in this study were organomontmorillonite, acid-activated montmorillonite and K, Ca, Zn and Cr montmorillonites produced by modifying the original montmorillonite sample. The evaluation and quantification of biodegradation and adsorption were carried out using a combination of the Iatroscan and gravimetric analysis. The SARA compositions in the presence of organomontmorillonite and acid-activated montmorillonite after incubation follow the same pattern in which the aromatic fraction is higher than the other fractions unlike in the presence of unmodified, K, Ca and Zn montmorillonites, where the saturates fraction is higher than the other fractions. Changes in SARA fractions due to biodegradation seemed to occur most in the presence of unmodified and calcium montmorillonites; hence, the removal of SARA fractions due to biodegradation was significant and enhanced in the presence of these two clay samples. However, biodegradation in the presence of organomontmorillonite and acid-activated and Cr montmorillonites was hindered. The study indicated that Cr montmorillonite adsorbed resins most, whereas Zn and K montmorillonites adsorbed aromatics most after incubation.     

Acid Particles and the Tracheobronchial Region of the Respiratory System—An “Irritation-Signaling” Model for Possible Health Effects

This paper explores some detailed mechanistic hypotheses for the possible action of acid particles on the tracheobronchial region of the human respiratory system. Because of the buffering capacity and volume of mucus produced per day it appears doubtful that ordinary ambient exposures to acid particles could markedly change the overall pH of tracheobronchial mucus considered as a whole. However it is possible that individual acidic particles could contain enough acid to deliver localized “irritant signals” that could be the triggers for enhanced mucus secretion and cell division in sensitive portions of the bronchial tree, and thereby contribute to the processes involved in chronic bronchitis.

Depending on the exact pH depression required for a “signal” to be perceived by the tracheobronchial epithelium, the acid content of the incoming particles per unit weight, and the effect of neutralization by ammonia in the upper respiratory tract, the minimum size of an acidic particle required to deliver a perceptible signal might range from about 0.4 to 0.7 microns for portions of the epithelium that are frequently swept by 4-micron mucus droplets. (For unprotected epithelium, however, it is conceivable that the minimum effective size for acid particles could be less.) Since particle number per unit weight declines dramatically with increasing particle size, the most potent fraction of particles in terms of signals delivered per μg/m³is likely to be just above the minimum size that is needed to produce an effective signal. The model developed here makes predictions of the relative potency of particles of different size and acid delivery capacity that could be tested in both experimental animal systems and human epidemiological studies.     

Floral scent variation in two <Emphasis Type="Italic">Antirrhinum majus</Emphasis> subspecies influences the choice of naïve bumblebees

Two wild subspecies of snapdragon, Antirrhinum majus, subspecies pseudomajus and striatum, differ in floral color and can be visually discriminated by insect visitors. The extent to which olfactory cues derived from floral scents contribute to discrimination between snapdragon subspecies is however unknown. We tested whether these two subspecies differ in floral scent and whether these olfactory differences are used by bumblebees (Bombus terrestris) to discriminate between them. We grew individuals of both subspecies, collected from a total of seven wild populations, under controlled conditions. We quantified the volatile organic compounds (VOCs) emitted by the flowers using gas-chromatography/mass-spectrometry/flame-ionization-detection. We studied antennal detection of VOCs by bumblebees, by means of electroantennogram study (EAG). We also performed behavioral experiments in a Y-maze to determine the innate response of bumblebees to the main floral VOCs emitted by our snapdragon subspecies. The floral scent of Antirrhinum majus pseudomajus contained three volatile benzenoids absent in the floral scent of Antirrhinum majus striatum. One of them, acetophenone, contributed over 69% of the absolute emissions of A. majus pseudomajus. These benzenoids elicited a significantly higher EAG response compared with other VOCs. In the Y-maze, bumblebees were significantly less attracted by acetophenone, suggesting an aversive effect of this VOC. Our findings indicate that bumblebees are able to discriminate between the two Antirrhinum majus subspecies. Differences in flower scent between these subspecies and olfactory bumblebee preferences are discussed in the light of biochemical constraints on VOCs synthesis and of the role of flower scent in the evolutionary ecology of A. majus.     

Photo-Stabilisation and UV Blocking Efficacy of Coated Macro and Nano-Rutile Titanium Dioxide Particles in Paints and Coatings

Surface treated macro and nanoparticle TiO₂ samples have been prepared, characterised and their efficiency as UV blockers evaluated in clear coatings and paints. The particle size of the ‘base’ TiO₂ has been optimised to block UV radiation and the surface treatment developed to deactivate the photocatalytic activity of the surface of the TiO₂ particles. The resultant UV blockers have been evaluated in both solvent and water-based clear coatings. Nanoparticle TiO₂ has been prepared from ‘seed’ and the particle size was controlled by calcination. It was found that the choice of particle size is a compromise between UVA absorption, UVB absorption, visible transmission and photoactivity. It has been demonstrated that TiO₂ with a crystallite size of 25 nm yields a product with the optimum properties. A range of dispersants was successfully used to disperse and mill the TiO₂. Both organic and inorganic dispersants were used; 2-amino-2-methyl-1-propanol and 1-amino-2-propanol (MIPA) and P₂O₅ and Na₂SiO₃ respectively. The surface of the nano-TiO₂ was coated with mixed oxides of silicon, aluminium, zirconium and phosphorous. Addition of the resultant coated nano-rutiles to an Isocyanate Acrylic clear coating prolonged the lifetime of that coating compared to the blank. Generally, a surface treatment based on SiO₂, Al₂O₃ and P₂O₅ was more successful than one based on ZrO₂, Al₂O₃ and P₂O₅. Higher addition levels of the surface treatment were beneficial for protecting the polymeric coating. The UV blocker products were also evaluated in a water-based acrylic, first a water-based dispersion of the UV blocker was prepared before addition to the acrylic. The dispersions and resultant acrylic thin films were evaluated using UV/Vis spectroscopy and durability assessed. The ratio of absorbance at 300:500 nm for the water-based dispersion was shown to be a good predictor of both the transparency of the resultant acrylic thin film and the durability of that film, in terms of weight loss. Macro grade titanium dioxide pigments were also prepared and coated with treatments of silica, alumina and siloxane and their photo-stabilising activity in alkyd paint film assessed and found to be directly related to the electron–hole pair mobility and trapping as determined by micro-wave spectroscopy.     

From concept to practice: the long road to operationalising protection

For the past two decades, humanitarian actors have been grappling increasingly with the complex issue of protecting civilians. The definition of protection adopted by humanitarians is considered to be too broad to provide effective operational direction. This paper aims to contribute to recent initiatives to operationalise protection. Teasing out a broad typology of humanitarian protection through an examination of the scope, objectives, and strategies of a range of humanitarian actors, it suggests, would result in better identification of gaps and the channelling of efforts to support a system‐wide protection response. Emphasising recent calls for collective analysis as a means of eventuating protection, the paper also draws attention to the contested understanding that may arise concerning solutions to protection crises. Closely entwined with politics, protection defies neat technical solutions. The paper concludes that deepening knowledge of how communities conceive their own interests may provide the basis for a collective protection response.