title: Characterisation of watersoluble polysaccharides produced during prehydrolysis of pinus radiata

authors: McDonald-Wharry, John

subjects: hemicellulose

abstract: An aqueous prehydrolysate (or prehydrolysis liquor) was produced during a mild
hot-water prehydrolysis (90 minute ramp to 175 C) of commercial radiata pine
wood chips. Oligosaccharide and polysaccharide material was separated from the
concentrated prehydrolysate using solvent precipitation after most of the noncarbohydrate
material was removed.
These polymeric carbohydrates were fractionated based on charge and molecular
weight by size-exclusion chromatography (SEC). The fractions were each
analysed by a number of methods including MALDI-ToF mass spectrometry, and
NMR. A number of different types of carbohydrate polymer structures were
found that were produced due to the partial de-polymerisation of the wood
hemicelluloses during the prehydrolysis process.
The O-acetylated (galacto)glucomannans were the most extensively characterised.
These partially-acetylated hexose-based polymers were the main type found and
accounted for approximately 54% by mass of the polymeric carbohydrates. Most
appeared to contained between 5 and 79 hexose units with differing degrees of
acetylation. The average mol ratio of components in these polymers was
calculated to be approximately 3.7 : 1.3 : 1 : 0.2 (D-mannosyl : acetyl : D-glucosyl
: D-galactosyl). They had a structure consistent with a linear backbone of β-1,4-
linked D-mannopyranosyl and β-1,4-linked D-glucopyranosyl units with acetyl
groups attached at C-2 and C-3 positions of some D-mannopyranosyl units. The
terminal D-galactopyranosyl units were likely to be attached at 1,4,6-linked Dmannopyranosyl
branch points. Of the neutral (non-anionic) polysaccharides, this
type was most prevalent in the higher molecular weight fractions.
Anionic pentose-based polymers with a backbone of β-1,4-linked D-xylopyranosyl
units were also characterised. Identified as (arabino)glucuronoxylans, they
featured uronic acid groups consistent with 4-O-methyl-α-D-glucopyranosyluronic
acids attached to the C-2 position of some D-xylopyranosyl units. Smaller
amounts of terminal α-L-arabinofuranosyl units likely to be attached at β-1,3,4-
linked D-xylopyranosyl branch points were also detected. These polymers
appeared to mostly contain between 5 and 40 pentose units with between 1 and 4
uronic acid groups attached.
The anionic fractions (approximately 30% by mass) also contained large amounts
of D-galactopyranosyl and L-arabinosyl units along with some D-glucuronic and
D-galacturonic acid residues. This suggested the presence of carbohydrates
produced from the partial hydrolysis of arabinogalactans and pectins.
The smaller molecular weight fractions of non-anionic polysaccharides were
enriched in both 1,4-linked D-galactopyranosyl units and non-acetylated hexosebased
polymers that contained between 5 and 30 hexose units; this suggested that
significant amounts 1,4-galactan derived carbohydrates were present. Small
amounts of oligomers containing only pentose units were detected in these smaller
molecular weight fractions along with what appeared to be other uncharged
fragments of the polysaccharide-types that were present in the anionic fractions.

text: Characterisation of watersoluble polysaccharides produced during prehydrolysis of pinus radiata An aqueous prehydrolysate (or prehydrolysis liquor) was produced during a mild
hot-water prehydrolysis (90 minute ramp to 175 C) of commercial radiata pine
wood chips. Oligosaccharide and polysaccharide material was separated from the
concentrated prehydrolysate using solvent precipitation after most of the noncarbohydrate
material was removed.
These polymeric carbohydrates were fractionated based on charge and molecular
weight by size-exclusion chromatography (SEC). The fractions were each
analysed by a number of methods including MALDI-ToF mass spectrometry, and
NMR. A number of different types of carbohydrate polymer structures were
found that were produced due to the partial de-polymerisation of the wood
hemicelluloses during the prehydrolysis process.
The O-acetylated (galacto)glucomannans were the most extensively characterised.
These partially-acetylated hexose-based polymers were the main type found and
accounted for approximately 54% by mass of the polymeric carbohydrates. Most
appeared to contained between 5 and 79 hexose units with differing degrees of
acetylation. The average mol ratio of components in these polymers was
calculated to be approximately 3.7 : 1.3 : 1 : 0.2 (D-mannosyl : acetyl : D-glucosyl
: D-galactosyl). They had a structure consistent with a linear backbone of β-1,4-
linked D-mannopyranosyl and β-1,4-linked D-glucopyranosyl units with acetyl
groups attached at C-2 and C-3 positions of some D-mannopyranosyl units. The
terminal D-galactopyranosyl units were likely to be attached at 1,4,6-linked Dmannopyranosyl
branch points. Of the neutral (non-anionic) polysaccharides, this
type was most prevalent in the higher molecular weight fractions.
Anionic pentose-based polymers with a backbone of β-1,4-linked D-xylopyranosyl
units were also characterised. Identified as (arabino)glucuronoxylans, they
featured uronic acid groups consistent with 4-O-methyl-α-D-glucopyranosyluronic
acids attached to the C-2 position of some D-xylopyranosyl units. Smaller
amounts of terminal α-L-arabinofuranosyl units likely to be attached at β-1,3,4-
linked D-xylopyranosyl branch points were also detected. These polymers
appeared to mostly contain between 5 and 40 pentose units with between 1 and 4
uronic acid groups attached.
The anionic fractions (approximately 30% by mass) also contained large amounts
of D-galactopyranosyl and L-arabinosyl units along with some D-glucuronic and
D-galacturonic acid residues. This suggested the presence of carbohydrates
produced from the partial hydrolysis of arabinogalactans and pectins.
The smaller molecular weight fractions of non-anionic polysaccharides were
enriched in both 1,4-linked D-galactopyranosyl units and non-acetylated hexosebased
polymers that contained between 5 and 30 hexose units; this suggested that
significant amounts 1,4-galactan derived carbohydrates were present. Small
amounts of oligomers containing only pentose units were detected in these smaller
molecular weight fractions along with what appeared to be other uncharged
fragments of the polysaccharide-types that were present in the anionic fractions.

year: 2010

title: Reading at risk: why effective literacy practice is not effective.

authors: Patel, Sheilpa

subjects: reading achievement

abstract: The gap between high and low achievers in reading is wide in New Zealand compared to other countries as shown in PIRLS (Progress in International Reading Literacy Study) 2001 and 2006 studies. Students of minority backgrounds and low socio-economic status are over-represented in the low achieving category. As the primary response to reduce the achievement gap, the Government developed and distributed the literacy teaching reference Effective Literacy Practice in Years 1 to 4. This article examines Effective Literacy Practice against current scientificbased international research in the teaching of reading, with particular emphasis on the teaching of reading to students at risk. Research evidence shows that an explicit and systematic approach to teaching reading is critical to the success of reading achievement with at-risk students. With a heavy leaning towards incidental learning, Effective Literacy Practice fails to provide teachers with the necessary knowledge to effectively teach the critical components of reading.

text: Reading at risk: why effective literacy practice is not effective. The gap between high and low achievers in reading is wide in New Zealand compared to other countries as shown in PIRLS (Progress in International Reading Literacy Study) 2001 and 2006 studies. Students of minority backgrounds and low socio-economic status are over-represented in the low achieving category. As the primary response to reduce the achievement gap, the Government developed and distributed the literacy teaching reference Effective Literacy Practice in Years 1 to 4. This article examines Effective Literacy Practice against current scientificbased international research in the teaching of reading, with particular emphasis on the teaching of reading to students at risk. Research evidence shows that an explicit and systematic approach to teaching reading is critical to the success of reading achievement with at-risk students. With a heavy leaning towards incidental learning, Effective Literacy Practice fails to provide teachers with the necessary knowledge to effectively teach the critical components of reading.

year: 2010

title: The government of themselves: Indigenous peoples' internal self-determination, effective self-governance and authentic representation - Waikato-Tainui, Ngāi Tahu and Nisga'a

authors: Joseph, Robert

abstract: The present thesis analyses the recognition and realisation of the international legal, human and the inherent right of Indigenous Peoples to exercise internal self-determination through effective self-governance within the nation-states of Canada and New Zealand. The following areas are reviewed in depth: first, internal self-determination which is, inter alia, about international fora and national governments recognising this fundamental right of Indigenous Peoples to self-govern as nations within; second, effective self-government which is, inter alia, about Indigenous Peoples having the authority and capability to govern themselves; and third, authentic representation which is, inter alia, a manifestation of internal self-determination and effective self-government at the indigenous local, regional and national operational levels. The challenges and issues that emerge at all levels, that is, between governments and indigenous entities, and within indigenous communities themselves, are examined extensively. The thesis findings highlight that the frequency and complexity of these challenges, as well as the inadequate and inappropriate fora and processes for resolution offered, make it incredibly difficult for Indigenous Peoples to recognise, realise and actualise the government of themselves.

text: The government of themselves: Indigenous peoples' internal self-determination, effective self-governance and authentic representation - Waikato-Tainui, Ngāi Tahu and Nisga'a The present thesis analyses the recognition and realisation of the international legal, human and the inherent right of Indigenous Peoples to exercise internal self-determination through effective self-governance within the nation-states of Canada and New Zealand. The following areas are reviewed in depth: first, internal self-determination which is, inter alia, about international fora and national governments recognising this fundamental right of Indigenous Peoples to self-govern as nations within; second, effective self-government which is, inter alia, about Indigenous Peoples having the authority and capability to govern themselves; and third, authentic representation which is, inter alia, a manifestation of internal self-determination and effective self-government at the indigenous local, regional and national operational levels. The challenges and issues that emerge at all levels, that is, between governments and indigenous entities, and within indigenous communities themselves, are examined extensively. The thesis findings highlight that the frequency and complexity of these challenges, as well as the inadequate and inappropriate fora and processes for resolution offered, make it incredibly difficult for Indigenous Peoples to recognise, realise and actualise the government of themselves.

year: 2005