Browsing by Author "Zhang R"

Now showing 1 - 3 of 3
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    Formation of by high power ultrasound aggregated emulsions stabilised with milk protein concentrate (MPC70)
    (Elsevier BV, 2021-12-03) Zhang R; Luo L; Yang Z; Ashokkumar M; Hemar Y
    In this work, oil-in-water emulsions stabilised by milk protein concentrate (MPC70) were investigated. The MPC70 concentration was kept constant at 5% (close to the protein content found in skim milk) and the oil volume fraction was varied from 20 to 65%. Sonication was performed at 20 kHz and at a constant power of 14.4 W for a total emulsion volume of 10 mL. Under certain oil concentration (≥35%) and sonication times (≥3s) the emulsion aggregated and formed high-viscosity pseudo plastic materials. However, the viscosity behaviour of the emulsion made with 35% oil reverted to that of a liquid if sonicated for longer times (≥15 s). Confocal laser scanning microscopy showed clearly that the oil droplets are aggregated under the sonication conditions and oil concentrations indicated above. An attempt to explain this behaviour through a simple model based on the bridging of oil droplets by the MPC70 particles and, taking into account the oil droplet and MPC70 particle sizes as well as the oil volume fraction, was made. The model fails to describe in details the aggregation behaviour of these emulsions, likely due to the inhomogeneous protein layer, where both free caseins and casein micelles are adsorbed, and to the packing of the oil droplets at concentrations ≤55%. Nonetheless, this work demonstrates the potential of ultrasound processing for the formation of dairy emulsions with tailored textures.
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    Monogenetic scoria cone and associated lava flow volume estimates and their controlling factors
    (Elsevier B V, Amsterdam, 2023-08) Zhang R; Brenna M; Kereszturi G
    Estimating eruption volumes of volcanoes is crucial for studying the development and evolution of volcanoes and assessing volcanic hazards. Volume estimates for polygenetic volcanoes are well-explored but individual monogenetic volcanoes have received less attention. This could be attributed to the lower perceived hazards resulting from their smaller size and rare eruptive occurrences within volcanic fields. However, accurately determining the volume of individual monogenetic volcanoes is significant for understanding volcanic field development and evolution. Estimates of individual monogenetic eruptions may be challenging due to overlapping lava flows from different vents within a volcanic field or underestimation resulting from the breaching of small-volume scoria cones. This study aims to evaluate the relationship between the morphometric parameters of scoria cones and the volumes of associated lava flows using the globally free Advanced Land Observing Satellite (ALOS) World 3D 30 m (AW3D30) DEM, the US National Elevation Dataset (NED) 10 m DEM, and related satellite images and terrain maps. The results show that the diameter of the scoria cone base (Wco) correlates best with the associated lava flow volume, and Wco is the parameter least affected by later onlapping lava flows. Numerous factors influence the volumes of monogenetic volcanic eruptions. The regional tectonic environment, such as tectonic setting and crust thickness, has been found to control Wco and hence the volume of monogenetic volcanoes. Subduction zones and thicker crust settings are characterized by the most voluminous monogenetic volcanoes. These environments facilitate the accumulation of magma, supporting larger volcanic eruptions. Magma density also correlates with monogenetic eruption volume. Lower density magma is more likely to erupt and form larger monogenetic volcanoes. Furthermore, pre-existing crustal weaknesses such as fault systems are the main factors affecting magma movement in monogenetic shallow plumbing systems and facilitate magma ascent to the surface. Local stresses appear to have a lesser influence on eruptive volumes. Magma source shape has minor influence on monogenetic eruption volumes. Evaluation of all these parameters will provide more robust estimates of potential eruption volumes, hence informing volcanic field hazards assessment
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    Variable controlling factors lead to contrasting patterns of volcanism in the Changbaishan volcanic area (Tianchi-Longgang), China-North Korea: Insights from morphometry and spatial-temporal analyses
    (Elsevier B V, Amsterdam, 2024-07-01) Zhang R; Brenna M; White JDL; Kereszturi G
    The coexistence of monogenetic and polygenetic volcanoes is a common phenomenon in volcanic areas. However, the genetic relationship between monogenetic and polygenetic systems and the factors controlling their distinct eruptive styles are not well understood. In active volcanic areas, analysing the clustering and vent alignment of monogenetic volcanoes, as well as examining the geomorphology and relative ages of scoria cones, offers quantitative insights into magma supply rates, volcano type distribution, and volcanic development trends. Our study presents geomorphological and spatio-temporal analyses of the co-existing monogenetic volcanoes in the Longgang Volcanic Field (LVF) and those associated with a polygenetic volcano (Tianchi) in the Changbaishan Volcanic Area, China. The distance between the two volcanic areas is around 150 km. Monogenetic vents in the LVF exhibit greater density compared to the dispersed system associated with Tianchi. The LVF vents also show better alignment, particularly in the direction of pre-existing basement faults (NE-SW, NW-SE and EW). By using scoria cone morphometric parameters and features, we estimated the relative ages and erupted volumes of monogenetic volcanoes in the LVF and the Tianchi area. We classified the cones of the two volcanic systems into five eruptive periods and found that, despite similar magma sources and output rates over approximately 870 kyr, differing numbers of scoria cones across age classes suggest that Tianchi's magma system influences its associated monogenetic volcanic plumbing. Furthermore, the continuous rise in output rates of monogenetic volcanoes in the Tianchi area highlights the increasing magma supply sustaining Tianchi volcano. Together, these interpretations are consistent with the two systems being controlled by different factors: the Tianchi monogenetic volcanic system is more controlled by magmatism, whereas the LVF is more strongly controlled by local tectonic structures, alongside an increasing magma supply causing the formation of progressively larger individual volcanoes. In volcanic areas, analysing monogenetic volcanoes' spatial-temporal distribution, volumes and recurrence rate provides a framework to evaluate magma supply rates and tectonic associations, which are key to the development of different volcano types.