The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform

Robert Hewson - One of the best experts on this subject based on the ideXlab platform.

  • The role of micro-cavitation on EHL: A study using a multiScale mass conserving approach
    Tribology International, 2015
    Co-Authors: Leiming Gao, Gn De Boer, Robert Hewson
    Abstract:

    The role of micro-cavitation in Elastohydrodynamic Lubrication is numerically investigated using a multiScale approach whereby both the small Scale topographical features and the micro-cavitation of the lubricant due to the features are resolved. Micro-cavitation and the fluid׳s shear-thinning property are modelled at the small Scale of topological feature. The effects of topographical features on the film thickness of the line contact Bearings and friction coefficient are presented with a focus on the role of micro-cavitation. This highlights how a mass conserving small Scale model can be used to model both micro-cavitation and cavitation occurring at the Bearing Scale, and how topological features can be designed to reduce friction while maintaining Bearing load.

Michael Schubert - One of the best experts on this subject based on the ideXlab platform.

  • Absolute Measurement of Thoron in Surface Waters
    Water, 2020
    Co-Authors: Derek Lane-smith, Michael Schubert
    Abstract:

    Thoron (radon-220, 220Rn, half-life 55.6 s) is a useful aqueous tracer suitable for applications such as locating and measuring groundwater discharge in surface waters (including the coastal ocean) and detecting radium-224 (224Ra) Bearing Scale inside water pipes. Generally, such applications require only relative thoron measurements in the water. However, if a thoron-in-water quantification in absolute numbers is desired the knowledge of the thoron sensitivity of the measurement system is obligatory. Absolute readings would, e.g., give a measure of the 224Ra activity in the sediment, supporting the thoron, or of the quantity of 224Ra in the pipe Scale. Since there is no standardised source of thoron-in-water (such as a NIST standard), there is no way to calibrate a thoron-in-water measurement system, in the usual sense. Up until now, therefore, it has not been possible to make absolute measurements of thoron in water. This paper presents a novel method of assessing the sensitivity of a mobile thoron-in-water measurement system. The paper analyses such systems and describes a straightforward experimental approach to obtain all setup-specific values of critical parameters that will allow a reasonably precise determination of the system thoron sensitivity. The method is simple enough that a thoron sensitivity calibration can be performed on site with no additional equipment.

Leiming Gao - One of the best experts on this subject based on the ideXlab platform.

  • The role of micro-cavitation on EHL: A study using a multiScale mass conserving approach
    Tribology International, 2015
    Co-Authors: Leiming Gao, Gn De Boer, Robert Hewson
    Abstract:

    The role of micro-cavitation in Elastohydrodynamic Lubrication is numerically investigated using a multiScale approach whereby both the small Scale topographical features and the micro-cavitation of the lubricant due to the features are resolved. Micro-cavitation and the fluid׳s shear-thinning property are modelled at the small Scale of topological feature. The effects of topographical features on the film thickness of the line contact Bearings and friction coefficient are presented with a focus on the role of micro-cavitation. This highlights how a mass conserving small Scale model can be used to model both micro-cavitation and cavitation occurring at the Bearing Scale, and how topological features can be designed to reduce friction while maintaining Bearing load.

Anca Miron - One of the best experts on this subject based on the ideXlab platform.

  • Pini cembrae coni: histo-anatomical and chemical studies, assessment of antioxidant activity
    Revista medico-chirurgicala a Societatii de Medici si Naturalisti din Iasi, 2012
    Co-Authors: Cristina Lungu Apetrei, Irina Boz, Elena Cenuşă, A Ionescu, Anca Miron
    Abstract:

    UNLABELLED This study aimed to identify some histoanatomical features, to evaluate the polyphenolic content and antioxidant activity of cembran pine female cones. MATERIAL AND METHODS The cross sections, obtained by usual techniques, were examined using a Novex microscope with a Canon A95 digital camera. For chemical and antioxidant assays dried cones were extracted with 80% aqueous methanol. The total phenolics, flavonoids and proanthocyanidins in cone extract were quantified by spectrophotometric methods. The antioxidant activity was investigated using different in vitro assays: ABTS radical cation scavenging assay, reducing power assay and ferrous ion chelating ability assay. RESULTS The histo-anatomical study of the seed-Bearing Scale revealed many secretory channels. The cone extract had low contents of total phenolics (48.03 +/- 0.10 mg/g), flavonoids (8.11 +/- 0.27 mg/g) and proanthocyanidins (1.63 +/- 0.03 mg/g). The extract scavenged ABTS radical cation and reduced ferric ions to ferrous ions with EC50 values of 64.6 +/- 0.8 and 118.60 +/- 1.89 microg/ml, respectively being less active than the positive control, quercetin (EC50 = 1.16 +/- 0.05 and 2.58 +/- 0.00 microg/ml, respectively). In ferrous ion chelating ability assay the extract showed a good activity (EC50 = 1.2 +/- 0.0 mg/ml) while quercetin was inactive. CONCLUSIONS The ability of cone extract to chelate ferrous ions encourages further studies for identification of bioactive constituents and evaluation of their protective effects against ferrous ion-induced oxidative stress.

  • PINI CEMBRAE CONI: STUDII HISTO-ANATOMICE ŞI CHIMICE, EVALUAREA ACŢIUNII ANTIOXIDANTE
    2012
    Co-Authors: Cristina Lungu Apetrei, Irina Boz, Elena Cenuşă, A Ionescu, Anca Miron
    Abstract:

    This study aimed to identify some histo-anatomical features, to evaluate the polyphenolic content and antioxidant activity of cembran pine female cones. Material and methods: The cross sections, obtained by usual techniques, were examined using a Novex microscope with a Canon A95 digital camera. For chemical and antioxidant assays dried cones were extracted with 80% aqueous methanol. The total phenolics, flavonoids and proanthocyanidins in cone extract were quantified by spectrophotometric methods. The antioxidant activity was investigated using different in vitro assays: ABTS radical cation scavenging assay, reducing power assay and ferrous ion chelating ability assay. Results: The histo-anatomical study of the seed-Bearing Scale revealed many secretory channels. The cone extract had low contents of total phenolics (48.03 ± 0.10 mg/g), flavonoids (8.11 ± 0.27 mg/g) and proanthocyanidins (1.63 ± 0.03 mg/g). The extract scavenged ABTS radical cation and reduced ferric ions to ferrous ions with EC50 values of 64.6 ± 0.8 and 118.60 ± 1.89 mg/ml, respectively being less active than the positive control, quercetin (EC50=1.16 ± 0.05 and 2.58 ± 0.00 mg/ml, respectively). In ferrous ion chelating ability assay the extract showed a good activity (EC50=1.2 ± 0.0 mg/ml) while quercetin was inactive. Conclusions: The ability of cone extract to chelate ferrous ions encourages further studies for identification of bioactive constituents and evaluation of their protective effects against ferrous ion-induced oxidative stress.

Derek Lane-smith - One of the best experts on this subject based on the ideXlab platform.

  • Absolute Measurement of Thoron in Surface Waters
    Water, 2020
    Co-Authors: Derek Lane-smith, Michael Schubert
    Abstract:

    Thoron (radon-220, 220Rn, half-life 55.6 s) is a useful aqueous tracer suitable for applications such as locating and measuring groundwater discharge in surface waters (including the coastal ocean) and detecting radium-224 (224Ra) Bearing Scale inside water pipes. Generally, such applications require only relative thoron measurements in the water. However, if a thoron-in-water quantification in absolute numbers is desired the knowledge of the thoron sensitivity of the measurement system is obligatory. Absolute readings would, e.g., give a measure of the 224Ra activity in the sediment, supporting the thoron, or of the quantity of 224Ra in the pipe Scale. Since there is no standardised source of thoron-in-water (such as a NIST standard), there is no way to calibrate a thoron-in-water measurement system, in the usual sense. Up until now, therefore, it has not been possible to make absolute measurements of thoron in water. This paper presents a novel method of assessing the sensitivity of a mobile thoron-in-water measurement system. The paper analyses such systems and describes a straightforward experimental approach to obtain all setup-specific values of critical parameters that will allow a reasonably precise determination of the system thoron sensitivity. The method is simple enough that a thoron sensitivity calibration can be performed on site with no additional equipment.