Very low inheritance in cosmogenic surface exposure ages of glacial deposits: A field experiment from two Norwegian glacier forelands

Terrestrial cosmogenic nuclide dating has been widely used to estimate the surface exposure age of bedrock and boulder surfaces associated with deglaciation and Holocene glacier variations, but the effect of inherited age has been rarely directly addressed. In this study, small clasts, embedded in flute surfaces on two cirque glacier forelands in Jotunheimen, southern Norway and deposited within the last ~60 years, were used to test whether such clasts have the modern surface exposure age expected in the absence of inheritance. Two different approaches were taken involving dating of (1) a single clast of cobble size from the proglacial area of Austanbotnbreen, and (2) 75 clasts mostly of pebble size from the proglacial area of Storbreen crushed and treated as a single sample. 10Be surface exposure ages were 99 ± 98 and 368 ± 90 years, respectively, with 95% confidence (±2σ). It is concluded that (1) these small glaciers have eroded and deposited rock fragments with a cosmogenic zero or near-zero concentration, (2) the likelihood of inherited cosmogenic nuclide concentrations in similar rock fragments deposited by larger warm-based glaciers and ice sheets should be small, and (3) combining a large number of small rock particles into one sample rather than using single large clasts of boulder size may provide a viable alternative to the commonly perceived need for five or more independent estimates of exposure age per site

Lennoxtown Essexite erratics train, central Scotland

This thesis is an investigation of glacial erratics derived from two small, adjacent, distinctive outcrops of essexlte near Lennoxtown, Central Scotland. Analysis of till samples has revealed that rock fragments and sand-size particles of essexite are absent up-ice of the essexite outcrops and scarce in a down-ice direction. Using dry stone walls as random samples of glacially transported stones, classic erratics train patterns of the distribution of erratics from both outcrops have been derived. The close spacing of Joints on one outcrop has led to the rapid disappearance of its erratics in the walls with distance from the source due to glacial crushing. Crushing is also shown by a size reduction of erratics from the other outcrop in the walls in a down-ice direction. Measurement of size and morphometric properties of essexite erratics has revealed that crushing is the dominant and abrasion a subsidiary process in glacial transport, whilst abrasion is dominant for particles that have undergone fluvioglacial and beach transport. Roundness appears to be the best measure differentiating between processes acting in the glacial, fluvioglacial and beach environments. Tests of compressive strength and experimental abrasion of essexite have been carried out to aid interpretation of the results. Tlll-particle preferred orientations, striae and the long axes of ice-moulded features snow a similar direction to that of the major axis of the train. From the evidence available it is suggested that the essexite wall stones underwent englacial transport in the lower layers of the last active ice and were deposited as an ablation mantle. A position of transport at the base of the ice is invoked for essexite particles in the till. The lateral spreading of essexite erratics down-ice of the source is attributed to divergence of basal ice flow around subglacial obstacles

Towards metal based anti-cancer agents : synthesis, structure, and biological studies

The most successful metal currently utilized in anti-cancer therapeutics is platinum. Despite its success though, cisplatin and other platinum derivatives have major limitations including high rates of drug resistance, a variety of side effects and a propensity to only work against cancers that have other, cheaper, treatments. For these reasons a considerable interest has emerged in developing other metal based anti-cancer therapeutics. In this work calixarenes are utilized for their metal co-ordination ability and low inherent toxicity to synthesise a number of metal complexes that are then put forward for initial anti-cancer activity.The first set of complexes are based on lanthanide ions (Eu, Gd, Tb) and p-sulfonatocalix[4]arene. Each complex consists of lanthanide ions bridging multiple calixarene molecules forming coordination polymers. The biological studies reveal low toxicity, suggesting that these complexes are suitable for optical imaging techniques rather than therapeutic use.The second set of complexes are based on simple endo rim functionalised calix[4]arenes forming complexes with titanium. There are similar systems in the literature however they have only been exploited for the catalytic potential in α-olefin polymerisation or ring opening polymerisation of cyclic esters. Initial studies of a calix[8]arene titanium complex is also presented. Biological studies reveal low toxicity for human brain glioblastoma cells.The final set are vanadium complexes of a range of linear phenolic ligands. Vanadium is a metal that is currently enjoying a resurgence in research around anti-cancer therapeutics having initially been designated as inactive. Biological studies again reveal low toxicity against human brain glioblastoma cells.All compounds synthesised for this work have been fully characterised with a number of crystal structures being presented

Synthesis, structures and cytotoxicity studies of p-sulfonatocalix[4]arene lanthanide complexes

A number of p-sulfonatocalix[4]arene complexes of the lanthanides (Tb, Gd, and Eu) have been prepared, some in the presence of tetraazamacrocycle 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A), and fully characterised. Crystal structure determinations reveal lanthanide coordination at the sulfonate group, bridging several calixarene units, giving coordination polymers. All complexes in this study have been determined to be relatively non-toxic using in vitro cell assays with CC₅₀ values in the range 30–170 μM

Patterns of soil water repellency change with wetting and drying: the influence of cracks, roots and drainage conditions

The influence of simulated cracks and roots on soil water repellency (SWR) dynamics with and without basal drainage impedance in wetting–drying cycles was investigated in the laboratory experiments. Observations and measurements were taken following water application equivalent to 9.2-mm rainfall and then periodically during 80 h of drying. In total, 180 experiments were carried out using 60 samples of three homogeneous, reconstituted soils with different organic matter contents and textures, but of similar initial severity of SWR [18% molarity of an ethanol droplet (MED)]. Water flowing down the cracks and roots left the soil matrix largely dry and water repellent except for vertical zones adjacent to them and a shallow surface layer. A hydrophilic shallow basal layer was produced in experiments where basal drainage was impeded. During drying, changes in SWR were largely confined to the zones that had been wetted. Soil that had remained dry retained the initial severity of SWR, while wetted soil re-established either the same or slightly lower severity of SWR. In organic-rich soil, the scale of recovery to pre-wetting MED levels was much higher, perhaps associated with temporarily raised levels (up to 36% MED) of SWR recorded during drying of these soils. With all three soils, the re-establishment of the original SWR level was less widespread for surface than subsurface soil and with impeded than unimpeded basal drainage.Key findings are that as follows: (1) with unimpeded basal drainage, the soils remained at pre-wetting repellency levels except for a wettable thin surface layer and zones close to roots and cracks, (2) basal drainage impedance produced hydrophilic basal and surface layers, (3) thorough wetting delayed a return to water-repellent conditions on drying, and (4) temporarily enhanced SWR occurred in organic-rich soils at intermediate moisture levels during drying. Hydrological implications are discussed, and the roles of cracks and roots are placed into context with other influences on preferential flow and SWR under field conditions

A Mutation in Amino Acid Permease AAP6 Reduces the Amino Acid Content of the Arabidopsis Sieve Elements but Leaves Aphid Herbivores Unaffected.

The aim of this study was to investigate the role of the amino acid permease gene AAP6 in regulating phloem amino acid composition and then to determine the effects of this altered diet on aphid performance. A genotype of Arabidopsis thaliana (L.) was produced in which the function of the amino acid permease gene AAP6 (At5g49630) was abolished. Plants homozygous for the insertionally inactivated AAP6 gene had a significantly larger mean rosette width than the wild type and a greater number of cauline leaves. Seeds from the aap6 mutant were also significantly larger than those from the wild-type plants. Sieve element (SE) sap was collected by aphid stylectomy and the amino acids derivatized, separated, and quantified using Capillary Electrophoresis with Laser Induced Fluorescence (CE-LIF). In spite of the large variation across samples, the total amino acid concentration of SE sap of the aap6 mutant plants was significantly lower than that of the wild-type plants. The concentrations of lysine, phenylalanine, leucine, and aspartic acid were all significantly lower in concentration in the aap6 mutant plants compared with wild-type plants. This is the first direct demonstration of a physiological role for an amino acid transporter in regulating SE composition in vivo. The amino acid availability in sieve element sap is thought to be the major limiting factor for aphid growth and reproduction. Despite the changes in their diet, the aphid Myzus persicae(Sulzer) displayed only small changes in feeding behaviour on mutant plants when measured using the Electronic Penetration Graph (EPG) technique. Salivation by the aphid into the SE (E1 phase) was increased on mutant plants but there was no significant effect on other feeding EPG behaviours, or in the rate of honeydew production. Consistent with the small effect on aphid feeding behaviour, there was only a small effect of reduced sieve element amino acid concentration on aphid reproduction. The data are discussed in relation to the regulation of phloem composition and the role of phloem amino acids in regulating aphid performance

Synthesis, structure, and cytotoxicity studies of oxidovanadium(IV and V) complexes bearing chelating phenolates

The interaction of [VO(acac)2] with 2,6-bis(hydroxymethyl)-4-methylphenol (L1H3) or 6,6/-methylenebis(4-tert-butyl-2-(hydroxymethyl)phenol) (L2H4) in refluxing toluene afforded, following work-up in ethanol, the complexes [VOL1]2 (1) and {[VO(acac)(HOEt)](VO)L2]}2 (2), respectively. Use of 4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]benzoic acid (L3H2) or 4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]benzosulfonic acid (L4H2) with [VOCl3] in refluxing acetonitrile, followed by methanol and THF work-up, afforded the complexes [Et3NH][VO(OMe)L3]2 (3) and [Et3NH][VO(OMe)L4]2 (4), respectively. The interaction of [VOSO4] and L3H2 in refluxing acetonitrile afforded, with extraction into methanol, the complex [VO(OMe)L3]2 (5). The molecular structures of 2, 3 and 5 have been determined; the structure of 1 has been reported previously. The complexes in this study have been determined to be of low toxicity using in vitro cell assays with 50% cytotoxicity values (CC50) values in the range 56 – 126 µM

Assessing water contamination risk from vegetation fires: Challenges, opportunities and a framework for progress

info:eu-repo/semantics/publishedVersio

Insignificant impact of prescribed fire on surface soil in a Pinus pinaster plantation, northern Portugal

Following a prescribed fire in a Pinus pinaster forest site located in the north-west Portugal, monitoring of any changes in selected soil characteristics and soil hydrology was undertaken to assess the effects of burning on the following: pH, electrical conductivity, water content, organic carbon and porosity. Thirty plots were established on a regular grid. At each sample plot before and after the fire, samples were collected (disturbed samples from depths of 0-1cm and 1-5cm; undisturbed core samples from 0-5cm). The results indicate that there was no measurable impact on the properties of the soil following this carefully conducted prescribed fire. The fire only affected the litter layer, as intended. Confirmation of this minimal impact on the soil was provided by regrowth of grasses and herbs already occurring two months after the fire. The implication is, therefore, that provided this wildfire-risk reduction strategy is carried out under existing strict guidelines, any impact on soil quality will be minimal