Toxicity increases in ice containing monochlorophenols upon photolysis: environmental consequences

The toxic effects of photoproducts formed upon the photolysis of 2- and 4-chlorophenol (CP) frozen solutions in polycrystalline ice phase were determined with a bacterial luminescence test (Vibrio fisheri), and in vitro biomarker assay for dioxin-like effects (inductions of AhR-dependent luciferase in H4IIE-luc cells) and compared to the toxic effects of products of the same photoreaction in aquatic phase. Coupling photoproducts formed in ice samples (3'-chlorobiphenyl-2,4'-diol and 3-chlorobiphenyl-2,2'-diol from 2-CP photolysis and 5-chlorobiphenyl-2,4'-diol from 4-CP photolysis) were found to be more toxic to V. fisheri than parent CPs and elicited significant inductions of dioxin-like effects (the effective concentrations EC50 approximately 3 x 10(-5) mol L(-1) corresponded to known weaker ligands of AhR, such as nonplanar polychlorinated biphenyls or polycyclic aromatic hydrocarbons). To complete the picture, a photoproduct formed from 4-CP (5-chlorobiphenyl-2,4'-diol) was synthesized, and a detailed toxicity assessment with purified compound confirmed the results obtained with irradiated samples. Our findings support a recently proposed model according to which solar radiation can trigger the formation of new types of organic pollutants in polar ice or tropospheric ice cloud particles, presenting possibly greater risk to the environment than the parent compounds.     

Basic theorem as representation of heterogeneous concept lattices

We propose a method for representing heterogeneous concept lattices as classical concept lattices. Particularly, we describe a transformation of heterogeneous formal context into a binary one, such that corresponding concept lattices will be isomorphic. We prove the correctness of this transformation by the basic theorem for heterogeneous as well as classical concept lattices.     

Comprehensive study on surfactant role on silver nanoparticles (NPs) prepared via modified Tollens process

Surfactants represent not only commonly used wetting agents but also substances that can be used as growth modifiers in the process of solid nanoparticle (NP) preparation. In this study we report influential character of different types of surfactants – i.e. ionic (SDS, CTAC) and non-ionic (Tween 80) – on fundamental characteristics of silver NPs, which were prepared by a modified Tollens process. The influential character of surfactants was evaluated throughout a reasonable improvement of the polydispersity (in the case of the tested non-ionic surfactants from 8.5% even down to 2.5%) and in the case of ionic surfactant, SDS and CTAC, also significant change of zeta potential (from −20 to −50 mV for the highest tested concentration of SDS). A slight influence of the tested surfactants was observed on the sizes of the prepared silver NPs. Therefore the obtained results from the performed surfactant-assisted syntheses revealed a possibility how to tailor silver NPs by means of their polydispersity and zeta potential according to the application demands.     

Assessment of Bioaerosol Generation and Sampling Efficiency Based on Pantoea agglomerans

This study was conducted to evaluate the effect of aerosol generation, relative humidity, and method of sampling on the culturability of the vegetative bacteria Pantoea agglomerans (P. agglomerans) formerly known as Erwinia herbicola. This research has relevance both for the use of this organism as a biowarfare simulant and for bioaerosol exposure assessment and public health. The culturability of P. agglomerans was tested using a test chamber against two generating systems (Collison and Bubble nebulizers), two sampling systems (the all-glass impinger (AGI-30), and the BioSampler), three collection media (water, TSB, and PBS) and across a range of humidities. Results indicated that the Bubble nebulizer was 15% more efficient in generating viable P. agglomerans counts (p ≤ 0.05). No difference was observed in overall efficiency between sampling methods (p > 0.05). However, as a collection media, PBS was observed to yield higher (p ≤ 0.01) viable counts compared to sterile deionized water. Relative humidity was found to strongly influence airborne P. agglomerans culturability. Culturable P. agglomerans was below the limit of detection for RH < 15% and then increased in a log-linear fashion to humidities of 75%. This research will help identify optimal means for evaluation of environmentally sensitive airborne bacteria for purposes of exposure assessment and public health as well as homeland security.     

A note on optimal floodlight illumination of stages

We consider the problem of illuminating a straight line segment with floodlights. The possible locations of the floodlights are given in advance and we want the total size of the floodlights to be minimum. We show that this problem admits a polynomial time algorithm even if we require that no two floodlights are placed at the same location.     

Alternate oils in fish feeds

Nearly half of the fish consumed as food worldwide are raised on fish farms rather than caught in the wild, as shown by FAO statistics. The increasing aquaculture of predatory carnivorous fish demands new sources of feed constituents, particularly oils at the moment. Common terrestrial plant oils contain only traces of the long‐chain polyunsaturated fatty acids. In connection with fish feed, especially the lack of n‐3 “marine fatty acids” is obvious. Recommendations on the required amounts of the fatty acids DHA (22:6n‐3) and EPA (20:5n‐3) exist from 1994. When plant oil‐based diets are fed during the growing phase and replaced by a fish oil‐based diet during a period prior to slaughter, most of the beneficial lipid composition of fish in terms of human dietary recommendations is restored. Little attention has been focused on the fish welfare in connection to substitution of dietary oil sources, and studies are still scarce. New fish diets will rely heavily on the use of alternate ingredients such as plant oils also for carnivorous cold‐temperate water fish species. In the future, an addition of synthetic or GMO‐produced “marine” fatty acids is a possible scenario. The aim of this review is to highlight some plant oils used in fish feeds, with special emphasis on compounds other than fatty acids. We also include some results from an ongoing study, where the effect of dietary soy oil on gonad maturation in Atlantic cod (Gadus morhua) is indicated.     

Glass and glass-ceramic coatings, versatile materials for industrial and engineering applications

Among various coating systems for industrial and engineering applications, glass and glass-ceramic coatings have advantages of chemical inertness, high temperature stability and superior mechanical properties such as abrasion, impact etc as compared to other coating materials applied by thermal spraying in its different forms viz. PVD, CVD, plasma, etc. Besides imparting required functional properties such as heat, abrasion and corrosion resistance to suit particular end use requirements, the glass and glass-ceramic coatings in general also provide good adherence, defect free surface and refractoriness. Systematic studies covering the basic science of glass and glass-ceramic coatings, the functional properties required for a particular end-use along with the various fields of application have been reviewed in this paper.