Restoration challenges for urban rivers.

Urban sources account for significant quantities of important diffuse pollutants, and urban watercourses are typically badly polluted. As well as toxic metals, hydrocarbons including PAHs, and suspended matter, priority urban pollutants include faecal pathogens and nutrients. Can urban watercourses be restored by sufficient reductions in pollution loads? Case studies in the UK and Sweden provide insights and some grounds for optimism. A major trans-Atlantic review of the performance of best management practices (BMPs) is informing BMP planning. New approaches such as the maximisation of self-purification capacity in the receiving waters may also need to be developed, alongside BMPs at source. Other initiatives in Europe, USA and China, including collaborative projects, are trying to address the intractable issues such as persistent pollutants from transport and urban infrastructure. The challenge is daunting, but there are clear ways forward and future research needs are evident.     

Photoinduced conversion of radiation polarization in integratedoptics components based on LiNbO3

Two photoinduced effects in LiNbO₃ optical waveguides (unidirectional waveguide mode conversion from ordinary to extraordinary polarization and radiation coupling out of waveguides with polarization plane rotation) are discussed. The circular photovoltaic tensor component in LiNbO₃ is determined experimentally, and a photovoltaic mechanism to explain photoinduced radiation coupling out of waveguides is proposed. The impact of the effects discovered on the performance of phase modulators is discussed     

Molecular interactions in aqueous solutions of the starch polysaccharides: a review

The aqueous solution behaviour of malto oligosaccharides, amylose and amylopectin is discussed. Experimental studies, using biophysical methods, on the aggregation behaviour of these compounds are reviewed.     

INHIBITION OF SHIKIMATE DEHYDROGENASE FROM HEART-OF-PALM (EUTERPE OLERACEA MART.)

Shikimate dehydrogenase (E.C.1.1.1.25), extracted from heart-of-palm, was purified by precipitation with ammonium sulphate and elution from columns of Sephadex G-25, and DEAE-Sephadex A-50. The enzyme was unstable and it was not possible to maintain the activity by the addition of cysteine and 2-mercaptoethanol to the buffer. The heart-of-palm contained two isoenzymes which were separated by polyacrylamide gel electrophoresis. The enzyme was inhibited by metal ions and p-CMB. The p-CMB inhibition was reversed by cysteine. The shikimate dehydrogenase was competitively inhibited by protocatechuic acid (Ki 7.5 × 10^?4M), and Km values of 0.021 mM and 0.011 mM for shikimic acid and NADP⁺, respectively, were obtained at pH 9.5 in Tris-HCl-glycine buffer. The molecular weight determination was performed on Sephadex G-100 and the MW was estimated to be 50,000 daltons.     

Bestimmung von Haselnußprotein (Corylin) mit Hilfe der Elektroimmundiffusion nach Laurell

European Food Research and Technology - Bei Bestimmungen des Proteingehalts von Haselnüssen in verschiedenen Handelsprodukten wie Nuß-Nougatcremes and Nußmus mit der...     

Non-point sources and the waste discharge charge system.

The development of a waste discharge charge system (WDCS) in South Africa has been proposed to promote waste reduction and water conservation. The WDCS is based on the polluter pays principle and is designed such that the management of waste discharges achieves resource quality objectives (RQOs) at the minimum total cost to the catchment. Two charges are distinguished: first a charge for optimising use of the resource (incentive charge); and secondly, a charge for development and operation of mitigation measures in the resource (mitigation charge). The WDCS is applied to both point sources and non-point sources (NPS) of contamination. In the inclusion of NPS, the charge system distinguishes between registered and non-registered NPS, with the charge applied to the former group only, in the first instance. This paper introduces the WDCS by describing the principles and the theoretical basis of the WDCS, highlighting the link to RQOs as the benchmark of acceptable externalities. The paper explores the inclusion of NPS in the WDCS, describing: first, the principles of NPS inclusion in the WDCS; secondly, the types of NPS included in the present version of the WDCS; thirdly, the methodology for charge estimation; and finally, non-registered NPS and their potential inclusion in future editions of the WDCS. The paper concludes with remarks and challenges facing the first edition of the WDCS.     

Corrosion and Crack Growth in 33% Na2O-67% SiO2 and 33% Li2O-67% SiO2 Glasses

Environmentally enhanced crack growth data for 33% Na₂O-67% SiO₂ and 33% Li₂O-67% SiO₂ (mol%) were obtained. Corrosion data for the same glasses as determined by infrared reflection spectroscopy and atomic absorption spectroscopy were also measured. It was determined that, of the tested environments, those and only those environments which caused surface corrosion also enhanced crack growth. Crack growth curves were more complicated for these materials than for fused silica. Water-dominated regions occurred even in environments which are known to enhance crack growth.