Shorelines Formed During Quaternary Marine Regression: Examples and Inferences from Southern Scotland (Progress Report)

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Agricultural Club

Papers concerning the Agricultural Club at Utah Agricultural College, including their objects, by-laws, constitution, and work

The young chronic sick at home and in hospital

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Pectic Substances in the Plant Cell Wall and Their Role in Potato Processing

The objective of this thesis was to characterise the chemistry of the pectin in the primary cell wall of two potato varieties, cv. Record and cv. Saturna, used in the crisp industry. The varieties chosen produce crisps with different textures. The original aim was to relate chemical characteristics of the pectin in the raw cell wall to textural differences in the crisp. A new procedure for the isolation of the cell wall, free from starch was developed. Methodologies to measure the pectic galacturonan, total ester and the extent of beta-elimination in the isolated cell wall were developed. Cell walls were isolated from raw, cold wash, hot wash, cold wash crisp and hot wash crisp samples from the 1995 and 1996 harvest. No significant differences in the pectin content or structure were found between the cell walls isolated from cv. Record and cv. Saturna. Nevertheless, the cell walls isolated following the crisping process had a reduced pectic galacturonan and methyl ester content. The neutral sugar content of the cell wall remained unchanged; however, the galactan and arabinan side chains had a greater mobility. As no significant differences between the varieties were found, the objectives were changed to monitor the pectin changes during processing. For comparison with crisping, slices of cv. Maris Piper were boiled for 2.5 minutes. Boiling resulted in pectin solubilisation (8%) with no reduction in the percentage galacturonan methyl esterification. Saponification followed by boiling caused 44% pectic galacturonan solubilisation. The pectin solubilised during cooking following saponification had a greater proportion of neutral sugars to galacturonan and had a smaller molecular-size distribution than the fraction solubilised by boiling alone. The maximum extent of beta-elimination in isolated cell walls of boiled cv. Saturna was estimated at 1%. Non-methyl esters were found at values of 14-15% in cv. Marfona and cv. Fianna. Chelation of divalent cations from the middle lamella resulted in the preferential solubilisation of a predominantly linear, non- methylated fraction of pectin. Saponification resulted in cleavage of ester crosslinks between pectic chains. Pectic chains whose anchorage in the cell wall relied on ester links were now held in the cell wall by divalent bridges. Boiling of the saponified tissue would result in the cleavage and loss of the cations into the cooking water, thus resulting in pectic solubilisation. Acid hydrolysis may have been an additional mechanism of cleavage of the pectic chain. Slices of the 1996 cv. Saturna harvest were crisped after saponification. The cffect of saponification on the quantities of pectin solubilised prior to the cooking process was reversed from boiling. Saponification prior to frying reduced the quantities of pectin solubilised due to the crisping process, 8% being solubilised from the saponified crisps and 40 % solubilised from the non-saponified crisps. Both saponification experiments resulted in solubilisation of the rhamnogalacturonan I fraction suggesting that the non-methyl esters occur within or close to the rhamnogalacturonan I fraction. The galacturonan and rhamnose units within the rhamnogalacturonan I do not provide sufficient sites for nonmethyl esterification. Ester linkages between the ester group of the homogalacturonan and the galactan side chains may provide alternative sites for ester linkages. A taste panel experiment was run on crisps following different pre-treatments. The pre-treatments that reduced the softening upon heating also conferred strength to the crisp. The crisping process involves cleavage of the methylated pectic chain due to beta-elimination in the cell wall resulting in the preferential solubilisation of a methylated homogalacturonan fraction. This mechanism of cleavage is prevented in the saponified crisp due to removal of the methyl ester groups. Anchorage of pectic chains whose ester cross links have been broken by saponification is maintained by divalent bridging. The saponified galacturonan has a greater potential for the formation of bridging due to the removal of the ester groups. There is a clear role for pectins in controlling the texture of the crisp, however, varietal differences can not yet be explained by differences in the raw cell wall

The impact of oxidation on spore and pollen chemistry

Sporomorphs (pollen and spores) have an outer wall composed of sporopollenin. Sporopollenin chemistry contains both a signature of ambient ultraviolet-B flux and taxonomic information, but it is currently unknown how sensitive this is to standard palynological processing techniques. Oxidation in particular is known to cause physical degradation to sporomorphs, and it is expected that this should have a concordant impact on sporopollenin chemistry. Here, we test this by experimentally oxidizing Lycopodium (clubmoss) spores using two common oxidation techniques: acetolysis and nitric acid. We also carry out acetolysis on eight angiosperm (flowering plant) taxa to test the generality of our results. Using Fourier Transform infrared (FTIR) spectroscopy, we find that acetolysis removes labile, non-fossilizable components of sporomorphs, but has a limited impact upon the chemistry of sporopollenin under normal processing durations. Nitric acid is more aggressive and does break down sporopollenin and reorganize its chemical structure, but when limited to short treatments (i.e. ≤10 min) at room temperature sporomorphs still contain most of the original chemical signal. These findings suggest that when used carefully oxidation does not adversely affect sporopollenin chemistry, and that palaeoclimatic and taxonomic signatures contained within the sporomorph wall are recoverable from standard palynological preparations

Patterns of biopsy-proven kidney disease amongst South African adults from 1995 to 2017

Introduction: Little data is available on biopsy-proven kidney disease in African countries. In this study, we have described the patterns of biopsy-proven kidney disease amongst South African adults encountered over a 23-year period and report whether these have changed over time. Methods: This retrospective study included all adults who underwent a native kidney biopsy at Tygerberg Hospital in Cape Town from January 1995 to December 2017. Only the first biopsy for each patient was included in the analysis. From patient records, we extracted demographic and clinical information and details of the kidney biopsies, including the indications and the final histopathological diagnosis. Results: During the study period, 2227 first native kidney biopsies were performed. The median age of the patients was 38.0 years (interquartile range 30.0–48.1 years), and 53.3% were female. The most common indication for biopsy was nephrotic syndrome (38.6%). Glomerulonephritis (GN) was the most common pattern of kidney disease, with similar numbers of cases of primary and secondary glomerular disease. Among the primary glomerular diseases, mesangiocapillary GN (34.5%) was the most common, followed by focal segmental glomerulosclerosis (22.3%) and membranous nephropathy (15.8%). Among the secondary glomerular diseases, lupus nephritis was the most common (39.1%), followed by human immunodeficiency virus-associated nephropathy (HIVAN, 22.1%), and diabetic nephropathy (14.4%). IgA nephropathy was uncommon, accounting for only 2.0% of all glomerular disease, as was hypertensive kidney disease, which was diagnosed in only 1.3% of all our biopsies. Conclusions: Over the last two decades, mesangiocapillary GN was the most common primary glomerular disease and lupus nephritis the most common secondary glomerular disease. There was a steady increase in the number of patients with HIVAN. Hypertensive nephropathy was an uncommon histological diagnosis, and IgA nephropathy remains rare

Letter from the Executive Committee of the Alumni Association

Letter concerning copies of a paper and a letter to be distributed at Utah Agricultural College

Proxy reconstruction of ultraviolet-B irradiance at the Earth’s surface, and its relationship with solar activity and ozone thickness

Solar ultraviolet-B (UV-B) irradiance that reaches the Earth’s surface acts as a biotic stressor and has the potential to modify ecological and environmental functioning. The challenges of reconstructing ultraviolent (UV) irradiance prior to the satellite era mean that there is uncertainty over long-term surface UV-B patterns, especially in relation to variations in solar activity over centennial and millennial timescales. Here, we reconstruct surface UV-B irradiance over the last 650 years using a novel UV-B proxy based on the chemical signature of pollen grains. We demonstrate a statistically significant positive relationship between the abundance of UV-B absorbing compounds in Pinus pollen and modelled solar UV-B irradiance. These results show that trends in surface UV-B follow the overall solar activity pattern over centennial timescales, and that variations in solar output are the dominant control on surface level UV-B flux, rather than solar modulated changes in ozone thickness. The Pinus biochemical response demonstrated here confirms the potential for solar activity driven surface UV-B variations to impact upon terrestrial biotas and environments over long timescales

Chemotaxonomy as a tool for interpreting the cryptic diversity of Poaceae pollen

The uniform morphology of different species of Poaceae (grass) pollen means that identification to below family level using light microscopy is extremely challenging. Poor taxonomic resolution reduces recoverable information from the grass pollen record, for example, species diversity and environmental preferences cannot be extracted. Recent research suggests Fourier Transform Infra-red Spectroscopy (FTIR) can be used to identify pollen grains based on their chemical composition. Here, we present a study of twelve species from eight subfamilies of Poaceae, selected from across the phylogeny but from a relatively constrained geographical area (tropical West Africa) to assess the feasibility of using this chemical method for identification within the Poaceae family. We assess several spectral processing methods and use K-nearest neighbour (k-nn) analyses, with a leave-one-out cross-validation, to generate identification success rates at different taxonomic levels. We demonstrate we can identify grass pollen grains to subfamily level with an 80% success rate. Our success in identifying Poaceae to subfamily level using FTIR provides an opportunity to generate high taxonomic resolution datasets in research areas such as palaeoecology, forensics, and melissopalynology quickly and at a relatively low cost

Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene.

The interfacial behaviour of water remains a central question to fields as diverse as protein folding, friction and ice formation. While the properties of water at interfaces differ from those in the bulk, major gaps in our knowledge limit our understanding at the molecular level. Information concerning the microscopic motion of water comes mostly from computation and, on an atomic scale, is largely unexplored by experiment. Here, we provide a detailed insight into the behaviour of water monomers on a graphene surface. The motion displays remarkably strong signatures of cooperative behaviour due to repulsive forces between the monomers, enhancing the monomer lifetime ( ≈ 3 s at 125 K) in a free-gas phase that precedes the nucleation of ice islands and, in turn, provides the opportunity for our experiments to be performed. Our results give a molecular perspective on a kinetic barrier to ice nucleation, providing routes to understand and control the processes involved in ice formation