Removal of two waterborne pathogenic bacterial strains by activated carbon particles prior to and after charge modification

Waterborne diseases constitute a threat to public health despite costly treatment measures aimed at removing pathogenic microorganisms from potable water supplies. This paper compared the removal of Raoultella terrigena ATCC 33257 and Escherichia coli ATCC 25922 by negatively and positively charged types of activated carbon particles. Both strains display bimodal negative zeta-potential distributions in stabilized water. Carbon particles were suspended to an equivalent external geometric surface area of 700 cm2 in 250 mL of a bacterial suspension, with shaking. Samples were taken after different durations for plate counting. Initial removal rates were less elevated for the positively charged carbon particle than expected, yielding the conclusion that bacterial adhesion under shaking is mass-transport limited. After 360 min, however, the log-reduction of the more negatively charged R. terrigena in suspension was largest for the positively charged carbon particles as compared with the negatively charged ones, although conditioning in ultrapure or tap water of positively charged carbon particles for 21 days eliminated the favorable effect of the positive charge due to counterion adsorption from the water. Removal of the less negatively charged E. coli was less affected by aging of the (positively charged) carbon particles, confirming the role of electrostatic interactions in bacterial removal by activated carbon particles. The microporous, negatively charged coconut carbon performed less than the mesoporous, positively charged carbon particle prior to conditioning but did not suffer from loss of effect after conditioning in ultrapure or tap water.     

Antifungal‐Inbuilt Metal–Organic‐Frameworks Eradicate Candida albicans Biofilms

Fungal biofilms cause a major clinical problem with a shrinking armamentarium for treatment. Here, the design and synthesis of voriconazole‐inbuilt zinc 2‐methylimidazolates frameworks (V‐ZIF) is reported. Voriconazole is built in through coordination‐binding between zinc and voriconazole. These metal–organic‐frameworks with inbuilt voriconazole, reduce inadvertent voriconazole‐leakage, yield a zero‐order release kinetics of voriconazole, aid antifungal penetration in Candida albicans biofilms, and prevent Candida aggregation yielding better dispersal. Once accumulated in an acidic C. albicans biofilm, voriconazole dissociates from the metal–organic framework to cause membrane‐damage and killing of inhabiting fungi. Moreover, in a murine model, the V‐ZIFs eradicate open‐wound infections caused by C. albicans better than voriconazole in solution, with negligible side effects to the healthy tissues of major organs. Thus, V‐ZIFs may provide a welcome addition to the antifungal armamentarium currently available for the treatment of fungal biofilms.     

From thickness dependent exit waves to projected potential: Thickness derivative approach

In HREM, due to multiple scattering, the exit wave of the object is nonlinear thickness dependent so that there is no one-to-one relation between object structure and the exit wave. This feature hampers the direct retrieval of structural information from exit waves. In this paper we discuss the possibility to restore the object structure in a direct way using exit waves of different thicknesses. It is theoretically shown that the amplitude of the thickness derivative exit wave |∂ψ/∂z| may directly reflect the project potential in a simple way. Image simulations show that it can be applied to restore the projected potential.     

The optimisation of extraction of antioxidants from potato peel by pressurised liquids

Response Surface Methodology was used to optimise the solid–liquid extraction and Pressurised Liquid Extraction of polyphenols from industrially generated potato peel. Efficiency of extraction was optimised by measuring antioxidant activity, phenol content and the level of caffeic acid. Conditions for optimal antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay were 75% ethanol, 80 °C and 22 min with solid–liquid extraction, resulting in an optimum activity of 352 mg Trolox Equivalents/100 g DW potato peel. In comparison, the use of Pressurised Liquid Extraction resulted in an optimum activity of 339 mg Trolox Equivalents/100 g DW potato peel at 70% ethanol and 125 °C. Therefore the use of Pressurised Liquid Extraction did not enhance extraction in comparison to solid–liquid extracts, but using aqueous ethanol as extraction solvent recovered a higher level of polyphenols than when using 100% methanol.     

Editorial special issue: house, home and dwelling

The aim of this special issue is to further our understanding of ‘house’, ‘home’ and ‘dwelling’ by presenting five empirical studies that investigate different aspects of these concepts. All three are complex, multi-faceted and multi-layered concepts, whose diverse connotations are often used interchangeably. For example, the word home is used for the physical structure of the house, for the meanings attached to the house, as well as for the process of homemaking. From an analytical point of view this is undesirable, since we require our concepts to be as unambiguous as possible. Therefore, in this introductory paper, the guest editors present a conceptual framework for studying house, home and dwelling that is based on the fundamental distinction between an environmental object and the affordances attached to it. The studies presented in this special issue investigate different aspects of house, home and dwelling, but they all use this conceptual framework and share the same theoretical perspective on people—dwelling relations. And, although each of the papers has its own merits, together they demonstrate that the conceptual framework is an effective tool for dismantling the concepts of house, home and dwelling.     

A Shape‐Adaptive,Antibacterial‐Coating of Immobilized Quaternary‐Ammonium Compounds Tethered on Hyperbranched Polyurea and its Mechanism of Action

Quaternary‐ammonium‐compounds are potent cationic antimicrobials used in everyday consumer products. Surface‐immobilized, quaternary‐ammonium‐compounds create an antimicrobial contact‐killing coating. We describe the preparation of a shape‐adaptive, contact‐killing coating by tethering quaternary‐ammonium‐compounds onto hyperbranched polyurea coatings, able to kill adhering bacteria by partially enveloping them. Even after extensive washing, coatings caused high contact‐killing of Staphylococcus epidermidis, both in culture‐based assays and through confocal‐laser‐scanning‐microscopic examination of the membrane‐damage of adhering bacteria. In culture‐based assays, at a challenge of 1600 CFU/cm², contact‐killing was >99.99%. The working‐mechanism of dissolved quaternary‐ammonium‐compounds is based on their interdigitation in bacterial membranes, but it is difficult to envisage how immobilized quaternary‐ammonium‐molecules can exert such a mechanism of action. Staphylococcal adhesion forces to hyperbranched quaternary‐ammonium coatings were extremely high, indicating that quaternary‐ammonium‐molecules on hyperbranched polyurea partially envelope adhering bacteria upon contact. These lethally strong adhesion forces upon adhering bacteria then cause removal of membrane lipids and eventually lead to bacterial death.     

Discharge Formulas of Crump-De Gruyter Gate-Weir for Computer Simulation

One of the problems of interest to professionals in the field of irrigation and drainage is the computer simulation of discharge or level control structures. Particularly troublesome are structures that display a marked change of behavior when the downstream water level exceeds a certain limit. The Crump-de Gruyter gate displays several such changes of behavior. Not only does it exhibit a transition from free to drowned flow when the downstream water level rises, it can also go from weir to gate flow. A series of experiments in a laboratory flume provided the basic data to test a simple mathematical model of this structure. The model assumes the structure is located between two reaches with sub-critical flow in the upstream and downstream reach.     

Review of Pathological anxiety: Emotional processing in etiology and treatment.

Reviews the book, Pathological anxiety: Emotional processing in etiology and treatment edited by Barbara Olasov Rothbaum (see record 2005-16244-000). This book is a tribute to the work of Edna B. Foa whose model of emotional processing has had a profound impact on the understanding and treatment of individuals with pathological anxiety. The first section of the book provides a series of chapters on theoretical conceptualizations of various anxiety disorders stemming from emotional processing theory. The second section of the book overviews assessment and treatment strategies stemming from emotional processing theory, across a spectrum of specific anxiety disorders. This book also contains chapters on unique clinical applications of emotional processing theory. Through its foundational focus on defining and explicating the importance of principles as outlined in emotional processing theory, this book's significance to the future of psychological treatments of anxiety is clear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prospects for Jatropha biofuels in Tanzania: An analysis with Strategic Niche Management

The paper reports on research in Tanzania about the scope for developing biofuels from an oil-seed bearing plant called Jatropha curcas Linnaeus. The plant is widely seen to have potential to help combat the greenhouse effect, help to stop local soil erosion, create additional income for the rural poor, and provide a major source of energy both locally and internationally. The principal analytic tool is Strategic Niche Management (SNM), an approach rooted in evolutionary innovation theory. We analyse how the scope for an energy transition is influenced by factors at three societal levels: the overarching ‘landscape’; the sectoral setting or ‘regime’; and the ‘niche’ level where the innovation develops and diffuses. Valuable niche processes were found in a few areas, especially in cultivation, but we conclude that there are still many obstacles in Tanzania's prevailing energy regime. The development of Jatropha biofuels is still in an early phase. We list policy recommendations and discuss some methodological issues arising from the use of SNM.