BURA Collection:

A multi-proxy palaeonenvironmental reconstruction from sediment cores, offshore Iran - Natural hazards and climatic change within the Late Holocene

2013-05-17T14:20:14Z

Title: A multi-proxy palaeonenvironmental reconstruction from sediment cores, offshore Iran - Natural hazards and climatic change within the Late Holocene Authors: Miller, Charlotte Sarah Abstract: During the last millennia, North African and Arabian palaeoclimatic records indicate a number of important climatic transitions. As a direct consequence, terrestrial ecosystems experiences significant changes. Although palaeoenvironmental records do exist in proximity to the north-western Arabian Sea, they remain sparse and provide little insight into environmental and climatic change of this region during the Late Holocene (the dating here is from 2300 cal. yr BP to present). Additionally, the north-western Arabian Sea is prone to natural disasters including recent cyclones and tsunamis such as the Makran tsunami, 1945 and cyclone Gonu, 2007, which leave a signal in the sediment. This thesis presents the results of detailed pollen and dinoflagellate cyst analysis in concert with a range of sedimentological techniques from sediment cores recovered from southern Iran (Chabahar Bay, Sea of Oman, Iran 25° 20’N, 60° 30’E). The data reveal the patterns of vegetation and oceanographic response to climatic change during the Late Holocene in the north-western Arabian Sea. Zonation on pollen and dinoflagellate results divides the last 2300 years into three distinct climatic phases: a wet period (2300 – 1830 cal. yr BP), a dry period (1830 – 1500 cal. yr BP) and a wet period (1500 – 120 cal. yr BP). The wet period (2300 – 1830 cal. yr BP) corresponds with well-known phases of intensive agriculture, including the Sassanid Period. The dry period (1830 – 1500 cal. yr BP) corresponds well with the end of the Beysehir occupation phase in southern Turkey. Moreover, an abrupt event is preserved in a single core and is dated at AD < 1808. Palynological evidence constrains the source of the sediment to be inner-continental but not of coastal origin, with a fluvial flood being the most likely mechanism of transportation. Description: This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.

Synthetic studies on Terpenoid lactones

2013-04-29T10:14:41Z

Title: Synthetic studies on Terpenoid lactones Authors: Toczek, Judy Abstract: A novel stereoselective route has been developed to a vernolepin intermediate in nine steps from 2-phenylthiocyclopentenone. During this research, a regiospecific method for the alkylation of the Δ5,6 - tetrahydroindanone system has been achieved. In addition, the synthetic route demonstrates a means of differentiating between two carboxylic acid functions via a selective lactonisation. The first total ynthesis of boonein has also been completed, in 3% yield from cyclopentadiene. This route uses a chlorine atom to direct the stereo- and regiochemical outcome of most of these reaction. Description: This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.

The global impact of climate change on fish

2013-04-22T11:13:49Z

Title: The global impact of climate change on fish Authors: Crawley, Natalie Elizabeth Abstract: Climate change is a global issue and the effects on fish populations remain largely unknown. It is thought that climate change could affect fish at all levels of biological organisation, from cellular, individual, population and community. This thesis has taken a holistic approach to examine the ways in which climate change could affect fish from both tropical, marine ecosystems (Great Barrier Reef, Australia) and temperate, freshwater ecosystems (non-tidal River Thames, Britain). Aerobic scope of coral reef fish tested on the Great Barrier Reef was significantly reduced by just a 2°C rise in water temperature (31, 32 and 33°C, compared to the current summer mean of 29°C) due to increased resting oxygen consumption and an inability to increase the maximal oxygen uptake. A 0.3 unit decline in pH, representative of ocean acidification, caused the same percentage loss in aerobic scope as did a 3°C warming. Interfamilial differences in ability to cope aerobically with warming waters will likely lead to changes in the community structure on coral reefs with damselfish replacing cardinalfish. Concerning Britain, there is evidence of gradual warming and increased rainfall in winter months over a 150 year period, suggesting that British fish are already experiencing climate change. It was evident from an analysis of a 15 year dataset on fish populations in the River Thames, that cyprinid species displayed a different pattern in biomass and density to all the non-cyprinid fish population, suggesting that there will be interfamilial differences in responses to climate change. Using a Biological Indicator Approach on the three-spined stickleback, Gasterosteus aculeatus, a 2°C rise in water temperature resulted in a stress response at the cellular and whole organism level. A 6°C rise in temperature resulted in a stress response at the biochemical level (higher cortisol and glucose concentrations), cellular level (higher neutrophil: lymphocyte ratio) and whole organism level (higher ventilation rate and lowered condition factor, hepatosomatic index and growth). G. aculeatus is considered to be temperature tolerant; therefore these results indicate that climate change may prove to be stressful for more temperature-sensitive species. This study has demonstrated that climate change will have direct effects on fish populations, whether they are in temperate regions such as Britain or in tropical coral reefs, but with strong interfamilial differences in those responses. Description: This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.

Studies of some fused-ring heterocycles and 2,6-Diarylpyridine derivatives

2013-03-08T14:21:46Z

Title: Studies of some fused-ring heterocycles and 2,6-Diarylpyridine derivatives Authors: Sadiq, Samina Abstract: This work reported is divided into two parts: the first part deals with quinoxaline derivatives and includes the preparation and characterisation of novel linear tricyclic quinones 1,4-diazanthracen-9,10-diones, (54) and (55). The reaction of diazanaphthoquinones and 1-acetyl-1,3-butadiene are used to produce these quinones through the Diels-Alder reaction. In addition hexaazapentacyclic 5,6,7,12,13, 14-hexaazapentacene was prepared by the reaction ofbis(2-chloroquinoxalin-3-yl)sulfide with thioxamide and the reaction of the sulfide with amines was investigated. Two different approaches to 6,13-dibutyl-5,6,7,12,13,14-hexaazapentacene are given. Derivatives of the pentacyclic, 6-thia- 5,7,12,13,14-pentaazapentacene and the unsubstituted 6,13 -dihydro compound are described. The novel N-(2,5-dimethoxy-6-nitrophenyl)guanidine is used to obtain 3-amino-5,6-dimethoxy-1 ,2,4-benzotriazine-1-oxide and 4,7 -dimethoxy-1 ,2,3 -benzotriazole is shown to be second product. Second part of the work is concerned with the development of a preparative route to 2,6-diphenylpyridines substituted with different groups on the phenyl nuclei. Several approaches were attempted. Finally, success was achieved and a series of compounds having basic chains of different length on the phenyl groups was prepared. One chain in each case had a terminal primary amine. The binding constants of the primary amines and their N-acetyl derivatives with DNA were determined using fluorescence spectroscopy. Description: This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.