title: The Study of the Antioxidant Activity of Phenolic Components of Manuka Honey

authors: Wang, Hao

subjects: Antioxidant activity

abstract: The phenolic compounds of honey have been known to pose significantly antioxidant activity, including iron-binding and free radical scavenging activity. Manuka honey has been widely used in wound treatment and the antioxidant activity of manuka honey is important in that. However, the antioxidant activity of phenolic compounds of manuka honey has been studied in a few of cases. The aim of this study was to identify the molecular structure of phenolic compounds of manuka honey mainly responsible for each type of antioxidant activity (iron-binding and free radical scavenging activity). The measurement of iron-binding type of activity was based on the inhibition of the Fenton reaction using the β-carotene-linoleic acid model system and the measurement of free radical scavenging activity was based on ABTS system. The phenolic extracts of manuka honey obtained off XAD column was run through Sephadex G-25 column. The elution was pooled to form fractions for assaying of antioxidant activity, so that the fractions with highest antioxidant activity can be detected. The fractions with highest antioxidant activity, including iron-binding and free radical scavenging activity, were re-run through Sephadex G-25 again, and the resulting fractions were assayed. After repeating fourth running through Sephadex G-25 column, 5 pools with highest antioxidant activity were obtained. The elution volumes of these 5 pools were mainly from 105.6 – 115.2 ml, indicating that this volume range had most of the antioxidant activity for phenolic extracts of manuka honey. Five pools were further separated by Superdex Peptide column on the FPLC system. The results showed that each pool was separated to have several main peaks. Each peak obtained from chromatography of all five pools was taken for activity assay. The peak with highest iron-binding activity was selected for structure identification by UV and mass spectra methods. The conclusion was made that the phenolic compound responsible for iron-binding type of antioxidant activity could be the molecule with molecular weight of 458.

text: The Study of the Antioxidant Activity of Phenolic Components of Manuka Honey The phenolic compounds of honey have been known to pose significantly antioxidant activity, including iron-binding and free radical scavenging activity. Manuka honey has been widely used in wound treatment and the antioxidant activity of manuka honey is important in that. However, the antioxidant activity of phenolic compounds of manuka honey has been studied in a few of cases. The aim of this study was to identify the molecular structure of phenolic compounds of manuka honey mainly responsible for each type of antioxidant activity (iron-binding and free radical scavenging activity). The measurement of iron-binding type of activity was based on the inhibition of the Fenton reaction using the β-carotene-linoleic acid model system and the measurement of free radical scavenging activity was based on ABTS system. The phenolic extracts of manuka honey obtained off XAD column was run through Sephadex G-25 column. The elution was pooled to form fractions for assaying of antioxidant activity, so that the fractions with highest antioxidant activity can be detected. The fractions with highest antioxidant activity, including iron-binding and free radical scavenging activity, were re-run through Sephadex G-25 again, and the resulting fractions were assayed. After repeating fourth running through Sephadex G-25 column, 5 pools with highest antioxidant activity were obtained. The elution volumes of these 5 pools were mainly from 105.6 – 115.2 ml, indicating that this volume range had most of the antioxidant activity for phenolic extracts of manuka honey. Five pools were further separated by Superdex Peptide column on the FPLC system. The results showed that each pool was separated to have several main peaks. Each peak obtained from chromatography of all five pools was taken for activity assay. The peak with highest iron-binding activity was selected for structure identification by UV and mass spectra methods. The conclusion was made that the phenolic compound responsible for iron-binding type of antioxidant activity could be the molecule with molecular weight of 458.

year: 2011

title: Current singularities in line-tied three-dimensional magnetic fields

authors: Craig, Ian J.D.

subjects: Science & Technology

abstract: This paper considers the current distributions that derive from finite amplitude perturbations of line-tied magnetic fields comprising hyperbolic field structures. The initial equilibrium on which we principally focus is a planar magnetic X-point threaded by a uniform axial field. This field is line-tied on all surfaces but subject to threedimensional (3D) disturbances that alter the initial topology. Results of ideal relaxation simulations are presented which illustrate how intense current structures form that can be related, through the influence of line-tying, to the quasi-separatrix layers (QSLs) of the initial configuration. It is demonstrated that the location within the QSL that attracts the current, and its scaling properties, are strongly dependent on the relative dimensions of the QSL with respect to the line-tied boundaries. These results are contrasted with the behavior of a line-tied 3D field containing an isolated null point. In this case, it is found that the dominant current always forms at the null, but that the collapse is inhibited when the null is closer to a line-tied boundary.

text: Current singularities in line-tied three-dimensional magnetic fields This paper considers the current distributions that derive from finite amplitude perturbations of line-tied magnetic fields comprising hyperbolic field structures. The initial equilibrium on which we principally focus is a planar magnetic X-point threaded by a uniform axial field. This field is line-tied on all surfaces but subject to threedimensional (3D) disturbances that alter the initial topology. Results of ideal relaxation simulations are presented which illustrate how intense current structures form that can be related, through the influence of line-tying, to the quasi-separatrix layers (QSLs) of the initial configuration. It is demonstrated that the location within the QSL that attracts the current, and its scaling properties, are strongly dependent on the relative dimensions of the QSL with respect to the line-tied boundaries. These results are contrasted with the behavior of a line-tied 3D field containing an isolated null point. In this case, it is found that the dominant current always forms at the null, but that the collapse is inhibited when the null is closer to a line-tied boundary.

year: 2014-06-20

title: Verbs in Māori: The problem of definitional criteria

authors: Whaanga, Hēmi

subjects: te reo Māori

abstract: A range of different types of criteria has been applied at different points in the history of the classification of verbs in Māori. These have included syntactic and morphological criteria, semantic criteria and derivational criteria. Unfortunately, these criteria have not always been applied consistently and this has led to considerable disagreement about the classification of verbs in Māori. In this paper, different accounts of verb classification in Māori are critically examined and it is argued that some of the disagreements can be resolved by acknowledging (a) that words in Māori may be assigned to different word classes in different contexts, and (b) that word classes and sub-classes should be determined on the basis of morphological and syntactic criteria with semantic and derivational information playing a role only in so far as they have observable syntactic and/or morphological consequences.

text: Verbs in Māori: The problem of definitional criteria A range of different types of criteria has been applied at different points in the history of the classification of verbs in Māori. These have included syntactic and morphological criteria, semantic criteria and derivational criteria. Unfortunately, these criteria have not always been applied consistently and this has led to considerable disagreement about the classification of verbs in Māori. In this paper, different accounts of verb classification in Māori are critically examined and it is argued that some of the disagreements can be resolved by acknowledging (a) that words in Māori may be assigned to different word classes in different contexts, and (b) that word classes and sub-classes should be determined on the basis of morphological and syntactic criteria with semantic and derivational information playing a role only in so far as they have observable syntactic and/or morphological consequences.

year: 2000-10