Generation and trapping of ketenes in flow

Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95?% conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (Ea = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precurso

Mineralization and nitrification: Archaea dominate ammonia-oxidising communities in grassland soils

In grasslands, N mineralization and nitrification are important processes and are controlled by several factors, including the in situ microbial community composition. Nitrification involves ammonia oxidising archaea (AOA) and bacteria (AOB) and although AOA and AOB co-exist in soils, they respond differently to environmental characteristics and there is evidence of AOA/AOB niche differentiation. Here, we investigated temporal variation in N mineralization and nitrification rates, together with bacterial, archaeal and ammonia-oxidiser communities in grassland soils, on different geologies: clay, Greensand and Chalk. Across geologies, N mineralization and nitrification rates were slower in the autumn than the rest of the year. Turnover times for soil ammonium pools were <24 h, whilst several days for nitrate. In clay soils, bacterial, archaeal, AOA, and AOB communities were clearly distinct from those in Chalk and Greensand soils. Spatially and temporally, AOA were more abundant than AOB. Notably, Nitrososphaera were predominant, comprising 37.4% of archaeal communities, with the vast majority of AOA found in Chalk and Greensand soils. AOA abundance positively correlated with nitrate concentration, whereas AOB abundance correlated with ammonium and nitrite concentrations, suggesting that these N compounds may be potential drivers for AOA/AOB niche differentiation in these grassland soils

Glycaemic Index, Glycaemic Load and dietary fibre characteristics of two commercially available fruit smoothies

In light of the updated Eatwell Guide and the corresponding change in the consumption of fruit smoothies, the aim of this study was to measure the glycaemic index and load of two commercial fruit smoothies and to investigate the retention of dietary fibre following production. In vitro analysis was performed to identify fibre material (cellulose and pectins) using calcofluor staining and immunocytochemical labelling. A repeated measures crossover study was conducted (n 10) to determine the Glycaemic Index (GI) and Glycaemic Load (GL) of the smoothies. Results showed that dietary fibre was still present in the smoothies after processing (16.9-17.5% cellular material by dry weight). The GI was low for both smoothies (39 and 36), whereas the GL was medium and borderline-low, respectively (11.4 and 9.7). The retention of fibre in these smoothies may have a potential positive effect on glycaemic response and may contribute to daily fibre requirements

Seroprevalence of Kaposi Sarcoma–associated Herpesvirus and Other Serologic Markers in the Brazilian Amazon

To determine the presence of Kaposi sarcoma–associated herpesvirus (KSHV) and other serologic markers, we tested serum specimens of 339 Amerindians, 181 rural non-Amerindians, and 1,133 urban blood donors (13 Amerindians) in the Brazilian Amazon. High KSHV seroprevalence in children and inverse association with herpes simplex virus type 2 indicates predominant nonsexual transmission among Amerindians

The role of glycosylphosphatidylinositol phospholipase D (GPI-PLD) in type one hypersensitivity

GPI-anchored proteins are a diverse group of molecules, which are ubiquitous in nature. The core structure of the GPI-anchor is highly conserved across a number of different species, a feature that implies a biological significance. Glycosylphosphatidylinositol-phospholipase D (GPI-PLD) is a 115 kDa glycoprotein which is found in high concentrations in mammalian serum. GPI-PLD hydrolyses GPI anchors, and it has been suggested that the enzyme is involved in the selective release of GPI-anchored proteins from the cell surface. GPI-PLD and GPI-anchored proteins have been implicated in a number of pathological situations, including T cell activation, insulin-mediated signalling and parasite immune evasion That GPI-PLD might play a role in the IgE-dependent activation of mast cells was suggested following experiments using a polyclonal antibody against bovine GPI-PLD. Inclusion of this antibody in experiments to activate mast cells lead to inhibition of the cells activation. However, this research was never completed. The research undertaken in this thesis has employed the Rat Basophilic Leukaemia cell line (RBL-2H3) as an analogue of Type One Hypersensitivity. IgE-dependent and independent stimulation of the cells was achieved, after which time the cells were employed in a variety of experiments to determine the role of GPI-PLD in their activation. Techniques were used to determine whether the cells generated the enzyme, It was determined that the cells did not generate mRNA, but contained the protein. The source of the enzyme was the Foetal Bovine Serum in the culture medium, and techniques were employed to inactivate or remove the enzyme from the serum. The effect on the cells behaviour was ascertained. Conclusions drawn were that RBL-2H3 cells employ a serum component, with characteristics of a GPI-PLD enzyme, in IgE-mediated activation

The role of glycosylphospatidyl inositol phospholipase D (GDI PLD) in type one hypersensitivity

Available from British Library Document Supply Centre- DSC:DXN058687 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Análisis teórico del algoritmo de compresión LLRUN para la compresión de cadenas de bits sparse

The purpose of this research was to make a theoretical analysis about the performance of LLRUN compression algorithm on sparse bit strings. Fraenkel and Klein (1985) proposed a method to compress sparse bit strings, using run length encoding (RLE), Elias - gamma coding and Huffman coding, with promising performance. The results of this research showed that LLRUN offers a theoretical compression ratio between 87,5% and 50%, being an effective tool to compress sparse bit strings. Keywords: compression, sparse bit strings, LLRUN, performance.La presente investigación tuvo como finalidad realizar un análisis teórico sobre el funcionamiento del algoritmo de compresión LLRUN, para determinar su posible uso en la compresión de cadenas de bits sparse. Fraenkel y Klein (1985) plantearon un método para comprimir cadenas de bits sparse mezclando las técnicas run length encoding (RLE), Gamma coding y Huffman coding, mostrando un rendimiento prometedor. El resultado del presente estudio permitió determinar que LLRUN ofrece una relación de compresión teórica entre 87,5% y 50%, siendo una herramienta efectiva para la compresión de cadenas de bits sparse. Palabras clave: compresión, cadenas de bits sparse, LLRUN, rendimiento