title: Fabrication of blended chitosan nanofibers by the free surface wire electrospinning

authors: AlJbour, Nawzat D.

abstract: Nanofibers are fibers with diameters in the nanometer range. They are characterized by their high surface area to volume ratio, flexible surface functionalities, and superior mechanical properties. Chitosan is a polycationic polymer which is abundant in nature. Chitosan nanofibers have been widely explored for different potential applications such as wound dressing, tissue engineering, and drug delivery systems. It is difficult to directly spin pure chitosan, due to its high molecular weight, low solubility, and high viscosity. To produce nanofibers, chitosan is commonly blended with other polymers that possess fiber forming capabilities such as polyvinyl alcohol, polycaprolactone, and Polylactic acid. In this study chitosan oligomers of an average molecular weight 15 kDa was blended with the three copolymers at different weight ratios. The fibers were prepared by the free surface wire electrospinning process, and the formed Chitosan nanofibers were characterized by Scanning Electron Microscopy (SEM). SEM results showed that blending chitosan with PLA enhances its spinnability and facilitates uniform and smooth morphology. Blending chitosan with PLA produced nanofibers with better quality, compared to PVA, and PCL.

text: Fabrication of blended chitosan nanofibers by the free surface wire electrospinning Nanofibers are fibers with diameters in the nanometer range. They are characterized by their high surface area to volume ratio, flexible surface functionalities, and superior mechanical properties. Chitosan is a polycationic polymer which is abundant in nature. Chitosan nanofibers have been widely explored for different potential applications such as wound dressing, tissue engineering, and drug delivery systems. It is difficult to directly spin pure chitosan, due to its high molecular weight, low solubility, and high viscosity. To produce nanofibers, chitosan is commonly blended with other polymers that possess fiber forming capabilities such as polyvinyl alcohol, polycaprolactone, and Polylactic acid. In this study chitosan oligomers of an average molecular weight 15 kDa was blended with the three copolymers at different weight ratios. The fibers were prepared by the free surface wire electrospinning process, and the formed Chitosan nanofibers were characterized by Scanning Electron Microscopy (SEM). SEM results showed that blending chitosan with PLA enhances its spinnability and facilitates uniform and smooth morphology. Blending chitosan with PLA produced nanofibers with better quality, compared to PVA, and PCL.

year: 2023-01-01

title: Late Miocene turnover of molluscan faunas, New Zealand: Taxonomic and ecological reassessment of diversity changes at multiple spatial and temporal scales

authors: Hendy, Austin J.W.

subjects: diversity

abstract: Previous estimates of molluscan biodiversity during the Neogene in New Zealand have revealed a pattern of significant diversity decline during the latest Miocene. This study uses an occurrence-based dataset (derived from published literature) to examine this pattern in further detail with both traditional synoptic measures and subsequent sampling standardization. Synoptic analyses of regional-scale data reveal diversity trajectories similar to those previously established, and rarefaction techniques demonstrate that the inferred pattern of Late Miocene diversity decline and Early Pliocene rebound is only somewhat biased by variations in sampling intensity. The pattern is also affected by temporal variations in the preservation of shelf paleoenvironments, with representation of highly diverse shallow-water facies varying considerably between biostratigraphic stages. The sampling and corresponding synoptic genus richness of biogeographic areas within the New Zealand region is also uneven. Within a single sedimentary basin sampled at high temporal resolution (Wanganui Basin), new data suggest that Late Miocene faunas were as diverse as those of the Early Pliocene, contrasting with the pattern of diversity decrease and subsequent increase observed at the regional spatial scale in prior studies. However, an ecological analysis of the new data demonstrates that turnover and restructuring of benthic communities did take place at the end of the Late Miocene. These findings suggest that spatial scale and temporal resolution are important considerations in determining the magnitude of diversity and ecological change observed in paleontologic studies. Contemporaneous biodiversity may not be similarly expressed at varying spatial or temporal scales in the fossil record. Rather, regional patterns of diversity change are governed by a complex interplay of not only large-scale environmental factors (e.g. temperature control), but also independent basin-scale processes (e.g. basin subsidence) and local sampling intensity.

text: Late Miocene turnover of molluscan faunas, New Zealand: Taxonomic and ecological reassessment of diversity changes at multiple spatial and temporal scales Previous estimates of molluscan biodiversity during the Neogene in New Zealand have revealed a pattern of significant diversity decline during the latest Miocene. This study uses an occurrence-based dataset (derived from published literature) to examine this pattern in further detail with both traditional synoptic measures and subsequent sampling standardization. Synoptic analyses of regional-scale data reveal diversity trajectories similar to those previously established, and rarefaction techniques demonstrate that the inferred pattern of Late Miocene diversity decline and Early Pliocene rebound is only somewhat biased by variations in sampling intensity. The pattern is also affected by temporal variations in the preservation of shelf paleoenvironments, with representation of highly diverse shallow-water facies varying considerably between biostratigraphic stages. The sampling and corresponding synoptic genus richness of biogeographic areas within the New Zealand region is also uneven. Within a single sedimentary basin sampled at high temporal resolution (Wanganui Basin), new data suggest that Late Miocene faunas were as diverse as those of the Early Pliocene, contrasting with the pattern of diversity decrease and subsequent increase observed at the regional spatial scale in prior studies. However, an ecological analysis of the new data demonstrates that turnover and restructuring of benthic communities did take place at the end of the Late Miocene. These findings suggest that spatial scale and temporal resolution are important considerations in determining the magnitude of diversity and ecological change observed in paleontologic studies. Contemporaneous biodiversity may not be similarly expressed at varying spatial or temporal scales in the fossil record. Rather, regional patterns of diversity change are governed by a complex interplay of not only large-scale environmental factors (e.g. temperature control), but also independent basin-scale processes (e.g. basin subsidence) and local sampling intensity.

year: 2009

title: Te Whakaruruhau Transition and Wellbeing programme: An implementation evaluation

authors: Robins, Kathryn

subjects: Maori

abstract: Based on the recognition that many women who come into refuge have few options
but to return to the sort of environment in which they have been abused, the
Transition and Wellbeing programme aims to provide medium to long term housing
for families as they re‐establish themselves in the community.
Data for the evaluation of the programme was collected from two main sources; the
women on the programme and key informants at Te Whakaruruhau. Five women,
two of whom are housed in transitional accommodation were interviewed
individually, while focus groups were conducted with middle and senior management
teams.
The completion of the interviews enabled the development of a programme logic,
which describes the ‘theory’ of the programme. The model details the activities or
what the programme does. These activities include linking women to programmes
and resources, providing practical support, addressing specific cultural needs and the
availability of quality advocates. These activities are built on foundational values, such
as, whanaungatanga, manaakitanga and wairuatanga. The programme is only made
possible with internal and external inputs. Of the external inputs, funding
contributions are considered vital to the functioning of the programme.
The women’s perspectives identified varying outcomes from their participation in the
programme. The logic model details the intended outcomes in the short, medium and
long‐term, reflecting personal, relational and community wellbeing. Short term
outcomes include improved communication, improved self‐esteem, improved
confidence and personal growth. Medium outcomes saw (re)engagement in training,
education and for some, (re)entry into the workforce. Long term outcomes related to
the establishment of a sustainable life style free from violence.
The participants did not see a need to modify the programme in any significant way.
Some did think that it could be usefully extended by adding to the existing activities a
hands on, artistic approach. Programme developers may consider more creative ways
in which to assess and measure the impact of the programme. Finally, it is suggested
that the programme could benefit from a more systemic assessment process to
determine whether women are “ready” to enter it.

text: Te Whakaruruhau Transition and Wellbeing programme: An implementation evaluation Based on the recognition that many women who come into refuge have few options
but to return to the sort of environment in which they have been abused, the
Transition and Wellbeing programme aims to provide medium to long term housing
for families as they re‐establish themselves in the community.
Data for the evaluation of the programme was collected from two main sources; the
women on the programme and key informants at Te Whakaruruhau. Five women,
two of whom are housed in transitional accommodation were interviewed
individually, while focus groups were conducted with middle and senior management
teams.
The completion of the interviews enabled the development of a programme logic,
which describes the ‘theory’ of the programme. The model details the activities or
what the programme does. These activities include linking women to programmes
and resources, providing practical support, addressing specific cultural needs and the
availability of quality advocates. These activities are built on foundational values, such
as, whanaungatanga, manaakitanga and wairuatanga. The programme is only made
possible with internal and external inputs. Of the external inputs, funding
contributions are considered vital to the functioning of the programme.
The women’s perspectives identified varying outcomes from their participation in the
programme. The logic model details the intended outcomes in the short, medium and
long‐term, reflecting personal, relational and community wellbeing. Short term
outcomes include improved communication, improved self‐esteem, improved
confidence and personal growth. Medium outcomes saw (re)engagement in training,
education and for some, (re)entry into the workforce. Long term outcomes related to
the establishment of a sustainable life style free from violence.
The participants did not see a need to modify the programme in any significant way.
Some did think that it could be usefully extended by adding to the existing activities a
hands on, artistic approach. Programme developers may consider more creative ways
in which to assess and measure the impact of the programme. Finally, it is suggested
that the programme could benefit from a more systemic assessment process to
determine whether women are “ready” to enter it.

year: 2008-06-26