Plasma and a cavitation bubble develop at the site of laser-induced breakdown in water. Their formation and the propagation of the shock wave were monitored by a beam-deflection probe and an ...arm-compensated interferometer. The interferometer part of the setup was used to determine the relative position of the laser-induced breakdown. The time-of-flight data from the breakdown site to the probe beam yielded the velocity, and from the velocity the shock-wave pressure amplitudes were calculated. Two regions were found where the pressure decays with different exponents, pointing to a strong attenuation mechanism in the initial phase of the shock-wave propagation.
In this paper, an optodynamic method for measurement of the shock wave front is presented. Two dimensional scanning was performed to determine the time-of-flight for each particular position of the ...probe beam. The interferometer part of the setup was used to accurately pinpoint the location of the laser induced breakdown. From the time-of-flight data we calculated the velocity field and found two regions of propagation of acoustic waves in water: a supersonic velocity region and a sonic velocity region. From the velocity the pressure amplitudes were calculated
In recent years the number of tailings dams failures has increased. On 25 January 2019, the Brumadinho tailings dam in Brazil suddenly failed, releasing a mudflow over 10 m deep comprising some 107 ...m3 of mining waste which killed between 270 and 320 people. This paper details the use of an agent-based model, known as the Life Safety Model (LSM), to estimate the risk to people downstream of the Brumadinho tailings dam and to assess if the number of fatalities could have been reduced if a warning had been received prior to or at time the dam failed. The LSM modelling indicates that even if a warning had been issued as the dam failed, the number of fatalities could have been reduced. Agent-based modelling tools such as the LSM can help to inform and improve emergency plans for tailings dams, which will help to reduce the risks posed by them in the future.
Phenolic compounds were measured in leaf tissues of apple cvs Jonagold and Golden Delicious, healthy and infected by Venturia inaequalis. Leaves were sampled from May to September 2005 and analyzed ...by high performance liquid chromatography. Hydroxycinnamic acids detected were chlorogenic, caffeic, ferulic and p-coumaric. In addition, the presence was ascertained of the dihydrochalcone phloridzin and the flavonoids epicatechin, catechin, rutin and quercitrin. Total phenolics were determined with the Folin-Ciocalteu method. Infection by V. inequalis caused an accumulation of phenolic compounds in infected leaves with a 1.4 to 6.2-fold increase of flavonols, a 2 to 6-fold increase of chlorogenic acid and a 1.4 to 2.4-fold increase of the Folin-Ciocalteu values.
The research dealt with phenolics in healthy versus scab infected apple leaves and fruits. The leaf samples were picked in the period from May to September and the fruit samples at technological ...maturity. Infection with the
Venturia inaequalis fungus enhanced the metabolism of phenolics at the infected sites, especially in the boundary tissue. Tissue infected with
Venturia inaequalis showed in comparison to the healthy tissue up to 7.6 times more hydroxycinnamic acids, up to 2.6 times more flavan-3-ols and up to 2.9 times higher values of flavanols. The content level of total phenolics in the infected tissue was 1.3–2.4 times higher than in the healthy leaves and fruit.
Individual organic acids and sugars were analysed in the fruits of scab resistant and susceptible apple cultivars. The total sugars ranged between 128.2 and 191.6
g/kg, and the total organic acid ...between 5.1 and 13.4
g/kg. In the flesh and peels of different apple varieties single phenolics (gallic, protocatehuic, chlorogenic, caffeic, ferulic and
p-coumaric acid, phloridzin, epicatechin, catechin, quercitrin and rutin) were analysed together with their total phenolic content (TPC). ‘Golden Delicious’ was the cultivar with the lowest TPC whereas ‘Rubinola’, ‘Jonagold’ and ‘Goldrush’ had the highest level of TPC in the pulp. Peels showed a 2–9 times higher phenolic content than the pulp. ‘Goldrush’ had the highest content of TPC in its peel. The total antioxidant capacity of peels was about 2–5 times higher than respective pulps. Scab resistant apple cultivars had significantly higher content of some single and total phenolic contents in comparison with the scab susceptible, especially the pulp.
Growth of an isolated bubble and horizontal coalescence events between bubbles of dissimilar size were examined during pool nucleate boiling of water on a horizontal, electrically-heated titanium ...foil 25
μm thick. Wall temperature measurements on the back of the foil by high-speed IR camera, synchronized with high-speed video camera recordings of the bubble motion, improved the temporal and spatial resolution of previous observations by high-speed liquid crystal thermography to 1
ms and 40
μm, respectively, leading to better detailed maps of the transient distributions of wall heat flux. The observations revealed complex behaviour that disagreed with some other observations and current modelling assumptions for the mechanisms of heat transfer over the wall contact areas of bubbles and interactions between bubbles. Heat transfer occurred from the entire contact area and was not confined to a narrow peripheral triple-contact zone. There was evidence of an asymmetrical interaction between bubbles before coalescence. It was hypothesised that a fast-growing bubble pushed superheated liquid under a slow-growing bubble. Contact of this liquid with regions of the wall that had been pre-cooled during bubble growth caused local reductions in the wall heat flux. During coalescence, movement of liquid under both bubbles caused further changes in the wall heat flux that also depended on pre-cooling. Contraction of the contact area caused a peripheral reduction in the heat flux and there was no evidence of a large increase in heat flux during detachment. Boiling on very thin foils imposes special conditions. Sensitivity to the thermal history of the wall must be taken into account when applying the observations and hypotheses to other conditions.
The phenolic profile of healthy and infected raspberry canes was investigated in three raspberry cultivars: Autumn Bliss, Himbo Top and Polka. The content of total phenols and tannins was determined ...using spectrophotometric methods, whilst individual phenolic acids, flavan‐3‐ols, ellagic acid derivatives and glycosides of quercetin were analysed using HPLC/MS analysis. The content of secondary metabolites varied considerably among the analysed raspberry cultivars. Moreover, Didymella applanata and Leptosphaeria coniothyrium infection significantly altered the metabolism of phenolic compounds. Flavanols represented the greatest share of all identified phenolics in raspberry canes (90%), followed by glycosides of quercetin (6%), derivatives of ellagic acid (3%) and traces of hydroxycinnamic acid derivatives. Spur and cane blight diseases caused an increase of flavan‐3‐ols and tannins but the levels of hydroxycinnamic acid derivatives, conjugates of ellagic acid and quercetin glycosides were significantly reduced. Cultivars Himbo Top and Polka contained higher levels of hydroxycinnamic acid and ellagic acid derivatives in healthy and infected canes compared to cv. Autumn Bliss. Cultivar Polka also contained the highest level of flavanols and tannins. However, despite high levels of flavanols and total phenols measured in cv. Polka, the canes were highly diseased following infection with D. applanata and L. coniothyrium. The results of the study provide evidence that the level of phenolic compounds in the canes could be causally linked to the differences in disease susceptibility.
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