On-surface Assembly of Au-Dicyanoanthracene Coordination Structures on Au(111)

On-surface metal-organic coordination provides a promising way for synthesizing different two-dimensional lattice structures that have been predicted to possess exotic electronic properties. Using scanning tunneling microscopy (STM) and spectroscopy (STS), we studied the supramolecular self-assembly of 9,10-dicyanoanthracene (DCA) molecules on the Au(111) surface. Close-packed islands of DCA molecules and Au-DCA metal-organic coordination structures coexist on the Au(111) surface. Ordered DCA$_{3}$Au$_{2}$ metal-organic networks have a structure combining a honeycomb lattice of Au atoms with a kagome lattice of DCA molecules. Low-temperature STS experiments demonstrate the presence of a delocalized electronic state containing contributions from both the gold atom states and the lowest unoccupied molecular orbital of the DCA molecules. These findings are important for the future search of topological phases in metal-organic networks combining honeycomb and kagome lattices with strong spin-orbit coupling in heavy metal atoms

Intermediate States of Graphene Nanoribbons

The downscaling of Si CMOS devices has encountered challenges related power and heat dissipation resulting in the need for new material selection. The use of single molecules, such as graphene nanoribbons (GNR), as transistors or device interconnects holds the possibility of significantly improving the performance and power consumption of consumer electronic devices. Recent developments in the synthesis of graphene nanoribbons have allowed for atomically precise construction via on-surface synthesis from molecular precursors. While the precursor toolbox for different GNRs has expanded rapidly, specific reaction pathways and the role of the catalytic metal substrate in the GNR growth have not yet been worked out in detail. In this work, low-temperature evaporation of planar dibromoperylene (DBP) was performed on a Cu(111) surface to determine the reaction pathway from individual DBP monomers to GNR formation. With controlled annealing, it was possible to synthesize intermediate structures step by step. Scanning tunneling microscopy (STM), non-contact atomic force microscopy (nc-AFM), and Kelvin-probe force microscopy (KPFM) experiments performed at low-temperature were used to confirm the evolution of the intermediate states to armchair nanoribbons. We find that the interaction between the Cu(111) surface and the DBP precursor influences the resulting GNR structure. The intermediate structures formed are stabilized by the Cu(111) substrate and further annealing results in armchair GNR formation

Economy and environment in the first millennium AD in Northern Scotland and the Northern Isles

Environmental remains taken from five, first millennium AD study sites broadly covering the Mid-Late Iron Age to Late Norse periods were analysed during the course of this research. Archaeobotanical material, including cereal grain, weed seeds, peat, seaweed and charcoal were identified and combined with other archaeological evidence, in particular animal / fish bone fragments, metallurgical finds, and the structural context. Cereal grain discoveries together with an analysis of the weed ecology, indicated agricultural intensification occurring during the later Iron Age / Pictish period. Metalworking held an important economic position in Pictish society, and an examination of the fuel resources from the study areas indicated movement and exchange in raw resources, such as wood, charcoal, and metal ore, occurring between the Northern Isles and Mainland Scotland. With the arrival of the Norse this north - south exchange system ceases to be in evidence, and it is not until the Late Norse period that inter-regional trade on an east - west market exchange basis is seen at the study sites. Research undertaken for this thesis indicated a period of pastoral expansion during the Late Norse period, particularly reflected by an increased need for fodder, and the necessity to produce surplus goods, such as dried fish, cereal grain and butter, for long distance trade. However, the beginnings of a pastoral dairying economy and intensification in arable productivity were seen in the pre- Norse / Late Iron Age period

Designing a strand orientation pattern for improved shear properties of oriented strand board

As oriented strand board (OSB) increases in use as an engineered wood product, improving the in-plane shear properties will allow more efficient use of the material as well as open up other opportunities for OSB to be used in engineered wood products with high shear stresses. Based on classical laminated plate theory, composite laminates with ±45° laminate alignment patterns produce higher in-plane shear modulus and strength when compared to typical 0°/90°/0° laminate alignment. This research consisted of manufacturing 13.3 mm thick OSB with 0°/+45°/-45°/45°/+45°/0° and 0°/90°/0° alignment patterns and comparing the in-plane shear, bending, nail connection, and small-scale shear wall properties with typical commercial OSB. The results showed an increase of 24% in measured average shear modulus for 0°/+45°/-45°/-45°/+45°/0° alignment when compared to 0°/90°/0° alignment using a method similar to the ASTM D2719-Method C in-plane shear test. The results show a 10% reduction in measured bending modulus of elasticity in the parallel direction. The small-scale shear wall tests were insensitive to changes in in-plane shear properties. The nail connection tests showed no reduction in yield load of the connection, implying that ±45° panels can be used in similar applications as 0°/90°/0° OSB without adversely affecting the connection properties

Metabolomics reveals diet-derived plant polyphenols accumulate in physiological bone

Plant-derived secondary metabolites consumed in the diet, especially polyphenolic compounds, are known to have a range of positive health effects. They are present in circulation after ingestion and absorption and can be sequestered into cells within particular organs, but have rarely been investigated systematically in osteological tissues. However, a small number of polyphenols and similar molecules are known to bind to bone. For example alizarin, a plant derived anthraquinone and tetracycline (a naturally occurring antibiotic), are both absorbed into bone from circulation during bone formation and are used to monitor mineralization in osteological studies. Both molecules have also been identified serendipitously in archaeological human bones derived from natural sources in the diet. Whether an analogous mechanism of sequestration extends to additional diet-derived plant-polyphenols has not previously been systematically studied. We investigated whether a range of diet-derived polyphenol-like compounds bind to bone using untargeted metabolomics applied to the analysis of bone extracts from pigs fed an acorn-based diet. We analysed the diet which was rich in ellagitannins, extracts from the pig bones and surrounding tissue, post-mortem. We found direct evidence of multiple polyphenolic compounds in these extracts and matched them to the diet. We also showed that these compounds were present in the bone but not surrounding tissues. We also provide data showing that a range of polyphenolic compounds bind to hydroxyapatite in vitro. The evidence for polyphenol sequestration into physiological bone, and the range and specificity of polyphenols in human and animal diets, raises intriguing questions about potential effects on bone formation and bone health. Further studies are needed to determine the stability of the sequestered molecules post-mortem but there is also potential for (palaeo)dietary reconstruction and forensic applications

Metabolomics as an Important Tool for Determining the Mechanisms of Human Skeletal Muscle Deconditioning

Muscle deconditioning impairs both locomotor function and metabolic health, and is associated with reduced quality life and increased mortality rates. Despite an appreciation of the existence of phenomena such as muscle anabolic resistance, mitophagy, and insulin resistance with age and disease in humans, little is known about the mechanisms responsible for these negative traits. With the complexities surrounding these unknowns and the lack of progress to date in development of effective interventions, there is a need for alternative approaches. Metabolomics is the study of the full array of metabolites within cells or tissues, which collectively constitute the metabolome. As metabolomics allows for the assessment of the cellular metabolic state in response to physiological stimuli, any chronic change in the metabolome is likely to reflect adaptation in the physiological phenotype of an organism. This, therefore, provides a holistic and unbiased approach that could be applied to potentially uncover important novel facets in the pathophysiology of muscle decline in ageing and disease, as well as identifying prognostic markers of those at risk of decline. This review will aim to highlight the current knowledge and potential impact of metabolomics in the study of muscle mass loss and deconditioning in humans and will highlight key areas for future research

Automated structure discovery in atomic force microscopy

Atomic force microscopy (AFM) with molecule-functionalized tips has emerged as the primary experimental technique for probing the atomic structure of organic molecules on surfaces. Most experiments have been limited to nearly planar aromatic molecules due to difficulties with interpretation of highly distorted AFM images originating from nonplanar molecules. Here, we develop a deep learning infrastructure that matches a set of AFM images with a unique descriptor characterizing the molecular configuration, allowing us to predict the molecular structure directly. We apply this methodology to resolve several distinct adsorption configurations of 1S-camphor on Cu(111) based on low-temperature AFM measurements. This approach will open the door to applying high-resolution AFM to a large variety of systems, for which routine atomic and chemical structural resolution on the level of individual objects/molecules would be a major breakthrough