The effects of environmental variables upon the lipid class and fatty acyl composition of a marine microalga: Nannochloropsis oculata (Droop) Eustigmatophyceae. Hibberd

Detailed analyses of the lipid class and fatty acid composition were carried out for the marine microalgal species Nannoch/oropsis oculata (Droop) (CCAP strain no. 849/1) of the division Eustigmatophyceae (Hibberd). The alga was grown in batch and continuous culture using a novel culturing apparatus, the cage culture turbidostat, the construction of which is detailed in full. The total lipid extract yielded by the alga varied in a growth-phase dependent manner within the range 25 % to 80 % of the lyophilised cell mass. Of this between 40 % and 70 % was recovered as fatty acid methyl esters (FAME) upon transesterification. The total fatty acid composition of N. oculata consisted mainly of 16:0, 16:1 and 20:5(n-3), these three fatty acids often accounting for greater than 80 % of the total fatty acid mass. Between 9 % and 50 % of the mass of total FAME was accounted for by 20:5(n-3), the balance being accounted for by variations in the relative proportions of 16:0, 16:1, 18:1, 18:2 and 20:4. During periods of low cellular division rate, such as the lag- and stationary-phases, the proportion of polyunsaturated fatty acids (PUFA) (mainly 20:5(n-3» decreased. The total fatty acids became increasingly saturated as higher proportions of shorter chain length fatty acids accumulated, mainly in triacylglycerols (TAO). Increased cellular proportions of total lipid resulted from TAO accumulation which occurred on account of preferential partitioning of carbon into TAO biosynthesis whilst cellular division was suspended. The fatty acid composition of the TAO was more saturated at high synthesis rate and vice-versa at lower rates. The galactolipids, monogalactosyldiacylglycerol (MODO) and digalactosyldiacyl glycerol (DODO) were rich in 20:5(n-3) during exponential cell division containing up to 77 % and 53 % 20:5(n-3) respectively. Phosphatidylcholine (PC) was the only cl~s to contain significant proportions of CIS fatty acids during exponential growth, thus implicating its involvement in the acyl chain elongation reactions between the Cl6 and <;0 fatty acids. Culture incubation temperature in the range 5 °C to 25°C did not influence the fatty acid composition of N. oculata. The effect of temperature upon culture dynamics at the lower culture incubation temperatures gave an apparent decrease in the PUFA content of the total fatty acid at a given point on the cultures growth curves. By expressing the data in tenns of culture doubling periods during the exponential-phases of growth it was found that temperature had no real effect upon fatty acid unsaturation or chain length. at either the total or the individual lipid class FAME level after the cells had passed through five doubling periods. Increasing the culture medium salinity from one quarter to one and a half times that of normal seawater decreased the un saturation and chain length of the fatty acids at both total and individual lipid class levels. The change resulted from the progressive accumulation of 18:1 and 18:2"at the expense of 20:5. Variation of salinity did not affect the dynamics of the cultures in the same respect as temperature in that a lag-phase was not observed on the cultures growth curves. However. such a phase was evident in the fatty acid profile of the cells in the period following inoculation. The 'effects of culture illumination intensity in the range 45 Jill m-2 sec-I to 170 Jill m 2 sec-! were examined under continuous culture conditions using the cage culture turbidostat Accumulation of saturated TAG by the cells at the higher illumination intensities gave an apparent decrease in the rate of PUFA biosynthesis. The polar lipid classes were found to be more highly unsaturated at higher illumination intensities. At lower illumination intensity TAG accumulation was reduced and the total fatty acid composition was accordingly more unsaturated. The fatty acid composition of the TAG component was more unsaturated but those of the polar lipid classes were less unsaturated than at higher illumination intensity. Increased illumination increased the degree of un saturation of the polar lipid cl~sses. Excess fixed carbon was partitioned into TAG biosynthesis. primarily as 16:0 and 16:1. The net accumulation of this lipid class even at high cell division rates resulted in a low overall unsaturation level. The effects of decreasing nitrate concentration in the range 1.0 mM N03 - to 0.001 mM N03 - had a similar basis to those of illumination in that the changes in the total fatty acid composition were largely governed by the rate of TAO accumulation. At high nitrate concentrations the cellular division rate was relatively high and the proportion of TAO in the total lipid extract was low. Consequently, both total and individual lipid classes contained high proportions of unsaturates, particularly 20:5(n-3). However, when the nitrate concentration was decreased, such that it began to limit the rate of cellular division, TAG accumulated Cursory analyses of the molecular species of the galactolipid classes, MODO and DODO, and phospholipid class PC are presented. The effects of environmental variables are discussed in tenns of the changes which may occur in the growth phase distribution of the cells in asynchronous culture, along with the concommitant changes in the lipid composition of the cells. The potential linkage of the elongation and desaturation reactions with both MODO and PC is also discussed briefly with reference to future research

A Critical Review to Plan the Future: An Infection Prevention and Control Conference with a Difference

This article discusses the program for the 4th International Australasian College for Infection Prevention and Control (ACIPC) Conference, which focuses on the future of infection prevention and control

Can bus really be the new tram?

Bus Rapid Transit (BRT) appears to be less expensive to build and operate than tram systems but can it really approach the performance level of a tram system and what is the environmental performance of comparable systems? This paper reports systematic research on these issues, particularly relating to where an urban transit system seeks to attract discretionary car users. A model has been developed to compare the implementation, operational costs and environmental impacts of a comparable tram and high quality guided BRT system. This models a UK situation, but draws upon information from elsewhere in Europe and North America. The design of the BRT system delivers equivalent performance to trams in capacity and passenger experience. This ‘equivalence’ model shows that the capital costs of the high-spec BRT system are two-thirds those of tram. This is less of a cost saving than is often claimed, suggesting that, in practice, BRT is built to a lower specification that tram systems. Operational costs do not significantly differ. Using hybrid-engine BRT vehicles, CO2 emissions are similar, BRT has lower PM10 emissions, but NOx from BRT remains higher than for trams. Although the cost differences for equivalent systems are less than is often claimed, there are substantial benefits in the flexible development of BRT, with it less vulnerable to variations from forecast ridership numbers, and development can be split into fundable stages, growing the business case for incremental upgrading. High-spec BRT can to be the new tram, but the ‘value for money’ case for BRT should not be at the expense of quality and transport planning impact

Early discontinuation of intravenous antimicrobial therapy in pediatric oncology patients with febrile neutropenia

BACKGROUND: There are no standard criteria for when to discontinue intravenous antimicrobial therapy (IVAMT) in children with febrile neutropenia (FN), but it is now common to discontinue IVAMT and discharge patients with an absolute neutrophil count (ANC) ≤ 500 /mm(3). The purpose of this study was to evaluate the outcome of a large cohort of children with FN who had IVAMT discontinued with an ANC ≤ 500 /mm(3) METHODS: A retrospective chart review was completed of patients in the Northern Alberta Children's Cancer Program with FN and no apparent clinical source of fever from June 1, 1997 to July 1, 2002. RESULTS: Out of a total of 275 patients, 127 (46%) had at least one episode of FN, with FN occurring in patients with sarcomas more commonly than in those with leukemia/ lymphoma and least in those with other solid tumors. In 59 of 276 episodes of FN (21%) patients had a microbiologically defined infection at admission. Of the 217 remaining episodes, 112 of 199 patients (56%) with known neutrophil counts had IVAMT discontinued before their absolute neutrophil count (ANC) reached 500 /mm(3 )at the discretion of the clinician. Fever recurred in only two of these patients after discharge, and there were no bacterial infections diagnosed after parenteral antibiotics were discontinued. CONCLUSION: Even without use of standard criteria for early discharge, clinicians appear to be skilled at selecting children with FN who can safely have IVAMT discontinued with an ANC ≤ 500 /mm(3)

A Novel Technique for the Separation of Dilute Butanol from Aqueous Fermentation Broths

Butanol is a promising biofuel which can be manufactured by fermentation. Irrespective of whether n-butanol or iso-butanol is produced, the alcohol is generally expressed at low concentrations (~1 wt%) in these fermentations. It also inhibits the organisms, and so removal of the butanol from the fermentation vessel as it is produced can improve the productivity of the fermentation. However, separation of dilute butanol from aqueous fermentation broths requires substantial amounts of energy. In this dissertation, a novel separation technique has been devised, employing the solvent extraction of butanol from aqueous broths by volatile hydrocarbons. This separation technique performs the separation of butanol selectively and efficiently. It is investigated theoretically in this dissertation. The use of volatile hydrocarbons allows the extracted butanol and the hydrocarbon to be separated by distillation, employing waste heat from the fermenter or other similar lowgrade heat sources. Such heat is often abundant on fermentation plants. Therefore, minimal high-grade heat (heat at temperatures higher than the fermenter) would be required for the process. The equilibria of butanol and side-products with C4 – C5 hydrocarbons were investigated using vapour-liquid equilibria and excess enthalpy measurements from the literature. Models of the extraction and distillation processes were then built using these analyses. A flowsheet simulation predicted that under 2 MJ/kg butanol of high-grade heat (mostly at only ~50°C) was required by the separation scheme provided that sufficient low-grade waste heat was available (~40 – 20 MJ/kg butanol for extraction of 1 – 2 wt% broths). This high-grade heat requirement is around 5% of the heat required for distillation of butanol from aqueous broths at 1 wt% Various configurations of flowsheet and solvent were investigated to improve the process. Distribution coefficients of butanol in C4 – C6 hydrocarbons were found to triple between 37°C and 100°C, and therefore extraction performed at elevated temperatures was found to significantly reduce the low-grade heat requirements of the system. The formation of butanol-gasoline blends via extraction of butanol into volatile hydrocarbons could also eliminate high-grade heat requirements.EPSRC Doctoral Training Gran

An fMRI investigation of moral cognition in healthcare decision making

This study used fMRI to investigate the neural substrates of moral cognition in health resource allocation decision problems. In particular, it investigated the cognitive and emotional processes that underpin utilitarian approaches to health care rationing such as Quality Adjusted Life Years (QALYs). Participants viewed hypothetical medical and nonmedical resource allocation scenarios which described equal or unequal allocation of resources to different groups. In addition, participants were assigned to 1 of 2 treatments in which they either did or did not receive advanced instructions about the principles of utilitarianism. In all cases, participants were asked to judged the proposed allocations as “fair” or “unfair.” More brain activity was observed within the superior parietal lobe, angular gyrus, middle temporal gyrus, and bilateral caudate nucleus when participants viewed scenarios depicting equal divisions of resources. Conversely, unequal resource divisions were associated with more activity in the inferior frontal gyrus and insula cortex. Furthermore, instructions about the principles of utilitarianism led to significant activation differences within the inferior frontal gyrus and the middle frontal gyrus. Significant differences in activity were also found within the inferior frontal cortex and anterior insula between medical and nonmedical scenarios. The implications for cognitive control mechanisms and the cognitive and neural bases of utilitarian ethical judgment are discussed