899 research outputs found

    The application of chiroptical spectroscopy (circular dichroism) in quantifying binding events in lanthanide directed synthesis of chiral luminescent self-assembly structures

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    The binding of asymmetrical and optically pure tridentate ligands (L = 1(S) and 1(R)) containing one carboxylic group and 2-naphthyl as an antenna to lanthanide ions (M = La(III) and Eu(III)) was studied in CH3CN, showing the successive formation of M:L, M:L2 and M:L3 stoichiometric species in solution. The europium complexes EuL3 were also synthesised, structurally characterised and their photophysical properties probed in CH3OH and CH3CN. The changes in the chiroptical properties of both 1(S) and 1(R) were used (by circular dichroism (CD) spectroscopy) to monitor the formation of these chiral selfassemblies in solution. While circularly polarised luminescence (CPL) showed the formation of Eu(1(S))3 and Eu(1(R))3 as enantiomers, with high luminescence dissymmetry factors (glum), fitting the CD changes allowed for binding constants to be determined that were comparable to those seen in the analyses of absorbance and luminescence changes

    Search for the Higgs boson via the H → b¯b decay mode, in the boosted regime on the ATLAS experiment

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    This thesis presents details of the search for the Standard Model Higgs boson, in the low mass region (100 ≤ MH < 150 GeV), with the ATLAS detector at CERN. In this range, a Higgs boson may be produced in association with a W or Z-boson and decay predominantly to two b-quarks (H → b¯b). Specifically events having large Higgs boson transverse momentum (pT > 200 GeV) and large recoiling W- boson transverse momentum (pT > 200 GeV) are considered as a means to reduce the contribution from background processes. In this high pT (boosted) regime, novel jet-substructure techniques are applied to the reconstructed jets resulting from the Higgs boson decay. In order to use these jet-substructure techniques, b-tagging efficiency scale factors in the jet-substructure regime have also been derived for the first time. Details of their derivation are presented for many b- tagging algorithms, with 14.3 fb¯¹ of ATLAS proton-proton collision data in 2012 at √s = 8 TeV. These, and their associated systematic uncertainties, are then applied to the Higgs boson search. No significant measurement of Higgs boson production was made, based on 20.4 fb¯¹ of ATLAS proton-proton collision data in 2012 at √s = 8 TeV. For a Higgs boson mass of 125 GeV, an exclusion limit of 6.12 x σSM was found at the 95% confidence level, and a signal strength of 0:93 ± 2:63 was measured, consistent with both background-only and signal (Standard Model Higgs boson) plus background hypotheses

    The reliability of performance during computer-simulated varying gradient cycling time trials

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    Ergometer based time trials are commonly used to assess performance changes due to training or other interventions. This investigation establishes the reliability of a novel computer simulated cycling time trial. Nineteen cyclists (age: 32 ± 12 years, mass 73 ± 11 kg, height 178 ± 5 cm) completed four time trials over a 20-km course which included numerous changes in gradient. The time trials were completed over a 4-week period in order to establish both short and long-term reliability. Performance time (mean ± SD) for trials one to four was 2265 ± 149 s, 2252 ± 153 s, 2236 ± 146 s and 2240 ± 154 s respectively; the corresponding power output for consecutive trials was 293 ± 35 W, 297 ± 36 W, 299 ± 35 W and 299 ± 35 W. The coefficient of variation (± 90% confidence limits) of performance for trials separated by 7, 14, 21 and 28 days was 1.1% (0.8% – 1.5%), 1.3% (1.1% – 1.9%), 1.3% (1.1% – 1.9%) and 1.5% (1.1% – 2.1%) respectively for time; the corresponding values for power output were 2.0% (1.5% – 2.7%), 2.3% (1.8% – 3.2%), 2.6% (2.0% – 3.6%) and 3.2% (2.5% – 4.5%). Further analysis based on rider ability indicated slower riders were less reliable than faster riders by a factor of ~1.1. Reliability of time trial performance diminishes with increasing time between trials. Additionally, faster riders show better reliability than slower riders over time. Researchers should consider the effect of time between trials and athlete ability when making conclusions about intervention effectiveness

    Dairy Ingredients in Chocolate

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    End of Project ReportThe main objective was to assess and control the contribution of various ingredient components to chocolate behaviour and to optimise ingredients for specific chocolate applications. A key aim, therefore, was to understand the role of composition and particle structure and to produce spray dried powders with a functionality in chocolate as close as possible to roller dried powders. By demonstrating how the powder properties affect chocolate, it should be possible to control the functional properties of the powders to meet any powder or chocolate specification. Novel powder compositions indicated by this work should also be useful to chocolate makers. The ability to make chocolate under test conditions and to assess the role of milk powders or other ingredients has been put in place for the first time in Ireland. Previous knowledge of milk seasonality and of powder technology has provided a basis for understanding variations in milk powder functionality in chocolate. Spray dried powders with mean free fat values of 50 to 94%, particle sizes of 30 to 65 mm and vacuole volumes of 0.0 to 3.9 ml/100g were produced from milks of varying composition but under the same processing conditions. Advances were made in analysing powder structure through microscopy, particle size and occluded air measurement. Valuable new information has been generated on the changes in free fat, solid fat content, particle size and occluded air in powders. Explanations were provided for the first time for the complex effects of these properties on chocolate viscosity and yield value. This information will also make a positive contribution to other projects in the milk powder area. Good contacts have been established with multinational manufacturers and with producers of milk powder for chocolate.Department of Agriculture, Food and the Marin

    Immediate re-hydration post-exercise is not coincident with raised mean arterial pressure over a 30-minute observation period

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    This investigation assessed the effects of immediate or delayed re-hydration post-exercise, on mean arterial blood pressure ( MAP) and on blood plasma volume (PV) expansion post-exercise. It was hypothesised that fluid ingestion would raise MAP and attenuate PV expansion. On two occasions separated by seven days, eight males ( age 20.4 +/- 1.7 years, mass 79 +/- 5 kg [ means +/- SD]; VO2 max 48 +/- 11 mL center dot kg(-1) center dot minute(-1), [mean +/- SE]) cycled in the heat (35 degrees C, 50% relative humidity) at a power output associated with 50% VO2 max, until 1.0kg body mass was lost. 1L water was given either immediately thereafter, or two hours post-exercise by random assignment. On both occasions, MAP was calculated every five minutes for a period of 30-minutes post-exercise, and change in PV was calculated 24-hours post-exercise. Repeated measures ANOVA for MAP results suggested a low probability of a treatment effect ( p = 0.655), a high probability of a time effect ( p = 0.006), and a moderately high probability of a time x treatment interaction ( p = 0.076); MAP tended to be lower when fluid had been consumed. PV expansions 24-hours post-exercise were not significant changes with respect to zero, and were not significantly different by treatment condition. In conclusion: ( a) The exercise was not sufficient to elicit significant PV expansions; thus, we were unable to determine the effects of the timing of post-exercise re-hydration on PV expansion. (b) The hypothesis regarding MAP in response to drinking was not supported, rather there was a 92% probability that the inverse affect occurs.C

    Plasma volume expansion 24-hours post-exercise: Effect of doubling the volume of replacement fluid

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    The effects of two volumes (1.5 L or 3.0 L) of commercially available electrolyte beverage (1.44 mM·L-1 Na+) taken during a 24-hour recovery period post-exercise, on plasma volume (PV) expansion 24-hours post-exercise were assessed. A simple random-order crossover research design was used. Subjects (n = 9 males: age 21 ± 4 years, body mass 80.0 ± 9.0 kg, peak incremental 60-second cycling power output 297 ± 45 W [means ± SD]) completed an identical exercise protocol conducted in hot ambient conditions (35°C, 50% relative humidity) on two occasions; separated by 7-days. On each occasion, subjects received a different volume of 24-hour fluid intake (commercial beverage) in random order. In each case, the fluid was taken in five equal aliquots over 24-hours. PV expansions 24-hours post-exercise were estimated from changes in haemoglobin and haematocrit. Dependent t-testing revealed no significant differences in PV expansions between trials, however a significant expansion with respect to zero was identified in the 3.0 L trial only. Specifically, PV expansions (%) were; 1.5 L trial: (mean ± SE) 2.3 ± 2.0 (not significant with respect to zero), 3.0 L trial: 5.0 ± 2.0 (p < 0.05, with respect to zero). Under the conditions imposed in the current study, ingesting the greater volume of the beverage lead to larger mean PV expansion.C

    Oxygen Uptake in Maximal Effort Constant Rate and Interval Running

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    This study investigated differences in average of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average and distance covered of 10 recreational male runners (: 4158 ± 390 mL·min−1) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at speed with 2 minutes at 50% of repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average for INT, 3451 (3269–3633) mL·min−1, 83% , was not significantly different to CRLT, 3464 (3285–3643) mL·min−1, 84% , but both were significantly higher than CR sub-max, 3464 (3285–3643) mL·min−1, 76% . The distance covered was significantly greater in CLRT, 4431 (4202–3731) metres, compared to INT and CR sub-max, 4070 (3831–4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run
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