Effect of solar ultra-violet radiation on the kelp Ecklonia radiata

During spring and summer, 1982–1986, experiments were carried out near Marmion Reef, Western Australia. In summer, nearly 30% of the surface solar ultraviolet radiation (280 to 400 nm) penetrates offshore waters to 5 m depth. Experimental removal of the mature Ecklonia radiata kelp canopy in summer results in tissue damage, photopigment destruction, reduced growth, and low survivorship of subcanopy kelp sporophytes. These effects do not occur with canopy removal in winter. Laboratory experiments revealed that the UV component of radiation, rather than intense photosynthetically active radiation, was responsible for the inhibition of growth and photodamage. UV radiation probably affects survival of the settlement stages of E. radiata sporophytes, thus excluding them from otherwise suitable substrata in shallow waters. UV radiation is implicated in the reduction of canopy productivity in summer.     

Prenatal diagnosis of the fragile X using thymidine induction

Eleven pregnancies in ten patients at risk for the fragile X were monitored by amniocentesis or chorion villus biopsy and induction of the fragile site using thymidine, methotrexate and FUdR. Three female fetuses and one male fetus were found to have the fragile X. The results obtained using thymidine induction were superior to those using methotrexate induction and probably better than those obtained using FUdR induction.     

Book reviews

Rebuilding the City: Property‐led Urban Regeneration

P. Healey, S. Davoudi, M. O'Toole, S. Tavsanoglu & D. Usher (Eds)

London, E. & F. N. Spon, 1992, 312 pp., £30

Der Wert stadtnaher Wälder als Erholungsraum: Eine ökonomishce Analyse am Beispiel von Lugano (Value of Urban Forests as Recreational Areas: An Economic Analysis on the Case of Lugano)

Claudia Nielsen

Chur (Switzerland), Verlag Rüegger, 1992, 261 pp., SFr 48

Urban Planning under Thatcherism: The Challenge of the Market

A. Thornley

London, Routledge, 1991, 253 pp., £14.99

Sustainable Development and Urban Form, European Research in Regional Science 2

M. J. Breheny (Ed)

London, Pion, Limited, 1992, 292 pp., £28.00.

Tourism, Museums and the Local Economy: The Economic Impact of the North of England Open Air Musuem at Beamish

Peter Johnson & Barry Thomas

Cheltenham, Edward Elgar, 1992, 160 pp., £29.50     

An Application of a Modified Ecological Footprint Method and Structural Path Analysis in a Comparative Institutional Study

This paper presents an application of a modified ecological footprint method, using a regional, disturbance-based approach. In contrast to conventional institutional ecological footprint calculations, energy and land use resulting from all upstream production processes are explored by employing an input-output framework. Ecological footprints are calculated for two research institutions: the School of Physics (SoP) at the University of Sydney, and the Sustainable Ecosystems (CSE) Department of the Commonwealth Scientific and Industrial Research Organisation. These are broken down further in terms of land disturbance and greenhouse gas emissions, and as a function of production layer. To enable the use of the results in policy formulation, the ecological footprints are decomposed into detailed contributing paths, which are ranked according to their importance, using structural path analysis. The paper demonstrates that a considerable proportion of impacts occur upstream in industrial production. Thus a significant result of the study is the weight of obscure paths in the total footprints and, therefore, the importance of conducting an holistic assessment in order to ensure all upstream contributions are captured in the final impact of the institution.     

The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

Applying metabolic fingerprinting to ecology: The use of Fourier-transform infrared spectroscopy for the rapid screening of plant responses to N deposition

The potential for metabolic fingerprinting via Fourier-transform infrared (FT-IR) spectroscopy to provide a novel approach for the detection of plant biochemical responses to N deposition is examined. An example of spectral analysis using shoot samples taken from an open top chamber (OTC) experiment simulating wet ammonium deposition is given. Sample preparation involved oven drying and homogenisation via mill grinding. Slurries of a consistent dilution were then prepared prior to FT-IR analysis. Spectra from control, 8 and 16 kg N ha^–1 yr^–1 treatments were then subjected to cross-validated discriminant function analysis. Ordination diagrams showed clear separation between the three N treatments examined. The potential for using Calluna vulgaris (L.) Hull as a bioindicator of N deposition is further evident from these results. The results also clearly demonstrate the power of FT-IR in discriminating between subtle phenotypic alterations in overall plant biochemistry as affected by ammonium pollution.     

Lightweight Concrete Containing an Alkaline Resistant Starch-Based Aquagel

Starch aquagel-based lightweight concrete has properties similar to those of other lightweight concrete products. However, starch aquagels are unstable in the strongly alkaline conditions typical of Portland Cement-based concrete and may interfere with the setting process. The effect of alkali treatments on the physical, mechanical, and functional properties of starch aquagels and aquagels from starch/polymer blends was investigated. Starch was blended at 100–115°C in a twin-screw extruder with five different polymers to determine whether the blends improved alkaline resistance. Polymer blends containing 5%, 15%, and 30% of the polymer hydrated and formed aquagels when equilibrated in water for 24 h. However, equilibrium moisture content was lower for the blends compared to the starch control. Aquagels equilibrated in 0.15 N NaOH swelled, lost compressive strength and had greater than 90% moisture. The blend of starch and 30% PVOH absorbed less moisture and was more resistant to alkaline dissolution in 1 N NaOH than the other blends tested making it a more suitable material for aquagel-based concrete. The moisture content of starch-based aquagels and mixing time were critical factors in determining setting times. The size of aquagel blends had a minor effect on density and compressive strength.