Effect of Crown Ethers on Sr2+, Ba2+, and Ra2+ Uptake by Tunnel‐Structure Ion Exchangers

Abstract

The effect of 15‐crown‐5 and 18‐crown‐6 ethers on the uptake of alkaline earth cations by tunnel‐structure ion exchangers polyantimonic acid (PAA) and cryptomelane manganese dioxide (CMD) was examined. In the case of PAA, 15‐crown‐5 and especially 18‐crown‐6 strongly influence the uptake of Sr²⁺ vs Ba²⁺ and Ra²⁺. For separation of the Ra²⁺‐Ba²⁺ pair, the effect of the crown ethers is insignificant. In CMD a small difference in complex formation between crown ethers and Ba²⁺ and Ra²⁺ gives an increase of separation. This effect is observed especially in 15‐crown‐5 solutions.     

Antimicrobial Siloxane Statistical and Graft Copolymers Substituted with t-Butylamine and t-Butylammonium Biocidal Functions

Two kinds of new biocidal siloxane copolymers were synthesized, poly-[3(t-butylamino)propyl]methylsiloxane-co-(3-chloropropyl)methylsiloxane] and poly[dimethylsiloxane-co-(3-mercaptopropyl)methylsiloxane]-g-poly-2(t-butylamino)ethyl methacrylate]. Water-soluble derivatives of these copolymers, having charged ammonium groups, were also obtained. The copolymers were tested against two Gram-positive and three Gram-negative bacterial strains. The antibacterial tests for the water-soluble copolymers with charged ammonium groups were performed in aqueous solutions. Both these copolymers were active against the Gram-positive bacterial strains and inactive or moderately active against Gram-negative bacteria. The uncharged, insoluble, t-butylamine substituted copolymers were tested using a two-phase water-copolymer system. In this test both copolymers having the uncharged t-butylamine functions showed a high biocidal potency against the bacteria studied including those Gram-negative ones.     

Accuracy of expansion charts – the influence of interstitial water chemistry

 Research on varve clays and Miocene clays in the Warsaw area has shown that the chemistry of the interstitial waters affects the plasticity index of the studied soils. As a consequence, the standard van der Merwe swelling potential chart and the Seed activity chart which are based on the plasticity index do not provide an accurate assessment of swell potential.

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Résumé La recherche sur les argiles varvées et les argiles miocènes de la région de Varsovie a montré que la chimie des eaux interstitielles affecte l'indice de plasticité de ce groupe de sols. En conséquence, le diagramme classique de gonflement de van der Merve et le diagramme d'activité de Seed qui sont fondés sur l'indice de plasticité, ne rendent pas correctement compte des gonflements potentiels.

     

Past Human Activities Recorded in the Landscape: A Case Study from the Glenveagh National Park,Ireland

The aim of the research was to investigate the persistence of landscape changes induced by former human activity in the area of the present Glenveagh National Park (NW Ireland), which was subject to intense depopulation and land abandonment in the middle of the nineteenth century. The research involved a field survey, including the earthwork survey of old anthropogenic landforms, as well as examination of available source materials, such as cartographic data (maps of habitats, land use maps) and aerial photographs. The research shows that human-induced landscape changes, old anthropogenic landforms and human-altered plant communities, are persistent in the environment, even in depopulated areas. The long-lasting persistence of anthropogenic earthworks is mainly due to the local environmental conditions, while the contemporary vegetation cover is mainly the result of economic factors, especially the long-term variations of land-use and the local economy. The present state of Glenveagh represents a cultural landscape, with both biotic and abiotic features influenced by long-term human impact. Therefore, the well preserved relics of the past can serve as a characteristic example of long-lasting human–environmental interactions. Such historic cultural landscapes are of a high educative importance and can be perceived as valuable ‘laboratories’ of human-induced environmental changes.     

Dyes based on the 6,7‐dichloro‐5,8‐quinolinedione skeleton as new type II photoinitiators for radical polymerisation

Several dyes based on the 6,7‐dichloro‐5,8‐quinolinedione skeleton have been synthesised and characterised by proton nuclear magnetic resonance spectroscopy and electron ionisation mass spectrometry. The spectroscopic and electrochemical properties of these dyes were investigated. Photoredox pairs consisting of the synthesised dyes and commercially available hydrogen donors (2‐mercaptobenzoxazole, 2‐mercaptobenzothiazole, 2‐mercaptobenzimidazole, and 2,5‐dimercapto‐1,3,4‐thiadiazole) were tested for use as effective initiator systems for radical polymerisation of trimethylolpropane triacrylate with visible light. The efficiencies of these initiator systems are discussed in terms of the free energy change for the electron transfer process from the dye to the hydrogen donor.     

Nanoscale Digital Devices Based on the Photoelectrochemical Photocurrent Switching Effect: Preparation,Properties and Applications

New materials and new phenomena which can be used for information processing always inspire great enthusiasm. On the other hand, silicon is still the main workhorse of modern electronics. Production of bulk quantities of ultrapure silicon is relatively cheap and the processing technologies are extremely sophisticated. Introduction of new materials and phenomena, on the other hand, requires an enormous amount of hard experimental and theoretical work. The photoelectrochemical photocurrent switching effect (PEPS) is one of the processes that, in principle, can evolve into new information processing technology. This review presents the effect itself, along with preparation of appropriate semiconducting materials, physical principles of semiconductor–molecule interactions, and finally some prototypical constructions of logic devices based on the PEPS effect.     

Three‐component terpolymers of glycidyl methacrylate with good swelling characteristics

Highly swellable glycidyl methacrylate terpolymers with styrene and a series of crosslinkers (divinyl benzene and ethylene, diethylene, and triethylene glycol dimethacrylates) were obtained by suspension polymerization. The loading capacities of the resins, their glass‐transition temperatures, and their swelling characteristics in 20 solvents were examined with respect to the monomer composition. A selected resin was modified for a cobalt–imine complex and tested as a catalyst in a model ring‐opening reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Screening of acrylamide contents in potato crisps using process variable settings and near-infrared spectroscopy

In order to study the formation of acrylamide in potato crisps during processing, an experimental design was set up. The design variables were drying time (6 levels), frying temperature (2 levels) and frying time (8 levels). The design contained 36 samples, which were analysed for acrylamide contents using LC high-resolution mass spectroscopy (LC-HRMS), and fat contents using the Soxhlet apparatus. Prior to analysis, all potato crisp samples were ground and analysed on an NIRSystems 6500 near-infrared (NIR) spectrometer. The acrylamide contents were modelled by: (i) design variables using multiple linear regression, (ii) NIR spectra using partial least squares regression (PLSR) and (iii) design variables and NIR spectra in combination using a novel technique combining least squares regression on the former, and PLSR on the latter. The results showed that the NIR spectra alone or in combination with the design variables gave better prediction models for acrylamide than the design variables alone. This implies that the spectra contain chemical information that is not purely a result of the processing variables that were investigated in this experiment. NIR spectroscopy is proposed as a possible tool for screening and identification of potato crisps with a high acrylamide content.     

Active food packaging evolution: transformation from micro- to nanotechnology

Predicting which attributes consumers are willing to pay extra for has become straightforward in recent years. The demands for the prime necessity of food of natural quality, elevated safety, minimally processed, ready-to-eat, and longer shelf-life have turned out to be matters of paramount importance. The increased awareness of environmental conservation and the escalating rate of foodborne illnesses have driven the food industry to implement a more innovative solution, i.e. bioactive packaging. Owing to nanotechnology application in eco-favorable coatings and encapsulation systems, the probabilities of enhancing food quality, safety, stability, and efficiency have been augmented. In this review article, the collective results highlight the food nanotechnology potentials with special focus on its application in active packaging, novel nano- and microencapsulation techniques, regulatory issues, and socio-ethical scepticism between nano-technophiles and nano-technophobes. No one has yet indicated the comparison of data concerning food nano- versus micro-technology; therefore noteworthy results of recent investigations are interpreted in the context of bioactive packaging. The next technological revolution in the domain of food science and nutrition would be the 3-BIOS concept enabling a controlled release of active agents through bioactive, biodegradable, and bionanocomposite combined strategy.     

Assessment of alkali–silica reaction damage through quantification of concrete nonlinearity

A newly developed nondestructive evaluation technique, Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS), is applied to concrete specimens in an ongoing assessment of aggregate alkali reactivity during standard concrete prism testing. NIRAS measures the nonlinearity in a specimen caused by the inception and growth of microcracks throughout the sample and debonding at the aggregate/cement interface. NIRAS is used to exploit the nonlinear effect of excitation amplitude dependent resonance frequency changes, which are related to nonlinearity measurements of concrete samples cast with aggregates of varying reactivity. To relate microstructural changes to changes in nonlinearity and expansion, sample characterization is performed with uranyl-acetate staining. The results demonstrate the utility of NIRAS for not only assessing the potential for ASR under standardized test conditions, but for more general damage characterization in concrete and assessment of “job mixtures.” NIRAS can distinguish reactive from nonreactive aggregates without ambiguity, as supported by sample characterization results.