title: Reinforced Sintered Cancellous Bovine Bone as a Potential Bone Replacement Material

authors: Laird, Dougal Frazer

abstract: This research was undertaken in order to investigate the possibilities of transforming a widely available waste bone resource into a viable human bone replacement biomaterial. Large quantities of bovine bone are available as a resource in New Zealand due to the presence of an extensive meat industry. Cancellous bone was harvested from within the condyle regions of bovine femoral bone by cutting with either band saw or lapidary saw. Portions of cut cancellous bovine bone were significantly defatted and partially deproteinated through repeated autoclaving. The material was then sintered at 1000°C for 3 hours to give a pristine white sintered cancellous bovine bone (SCBB) material, that although weakened in comparison to its original form, retained the porous trabecular architecture of the original cancellous bone. This material was characterised by means of Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD), while also being subjected to a washing experiment in distilled water with pH monitoring to show that the material was hydroxyapatite (HAp) (Ca10(PO4)6(OH)2) with small quantities of CaO. Scanning Electron Microscopy (SEM) showed that the SCBB material had retained its macroporous architecture, with higher magnification micrographs revealing a microporosity with channels through crystallites of the HAp of approximately 500 – 700 nm in diameter. Organic infiltrating solutions were prepared by dissolving chitosan in hydrochloric acid in addition to calcium phosphate, such as HAp or CaHPO4, to act as a mineral reinforcing material. Due to the limited solubility of HAp, the maximum concentration that could be achieved involving a 50 : 50 w/w combination of chitosan and HAp was 6 g L-1 for both materials in ~ 0.1 mol L-1 HCl. ε Polycaprolactone (PCL) dissolved in tetrahydrofuran (THF) was also trialled as an infiltrating solution, with concentrations up to 14 % w / v dissolved in the THF. Solutions were infiltrated into the porous SCBB material by means of vacuum, vacuum and pressure or a pressure only method. The extent of penetration of the infiltrate into the SCBB was followed by labelling the chitosan molecule with the fluorophore, Fluorescein Isothiocyanate (FITC) and then examining the infiltrated SCBB by fluorescence microscopy. After infiltration into the SCBB material, chitosan and mineral reinforcing were precipitated by an increase in pH. Several methods for increasing solution pH were trialled, including; the addition of urea into the infiltrating solution with subsequent thermal hydrolysis, the catalysis of urea by urease, and treatment with ammonia gas. By products and excess ammonia were shown to be able to be removed from the infiltrated SCBB by repeated washing in water and buffer solution. Mechanical testing on the infiltrated SCBB material was carried out by compression testing on an Instron materials testing instrument. Due to the inherent variability in the density and strength of the starting SCBB material, a statistical approach was required. Multiple samples were used and values for ultimate stress, modulus and a modified toughness measurement obtained from the mechanical testing for non-infiltrated SCBB samples were compared against infiltrated samples. SCBB samples infiltrated with a chitosan / CaHPO4 infiltrate displayed an improvement in ultimate stress, while samples infiltrated with PCL showed an overall increase in modulus. Finally, biocompatibility of the SCBB samples infiltrated with chitosan based infiltrates was tested using L929 fibroblast cell culture testing and a Hen’s Egg Test - Chorioallantoic Membrane (HET-CAM) test. Materials with low cytotoxic response were produced when sufficient washing and buffer treatment was employed after infiltration. This research proved that SCBB could be successfully infiltrated with an organic / mineral composite matrix, which was capable of modifying the mechanical properties of the SCBB, while displaying positive biocompatibility potential.

text: Reinforced Sintered Cancellous Bovine Bone as a Potential Bone Replacement Material This research was undertaken in order to investigate the possibilities of transforming a widely available waste bone resource into a viable human bone replacement biomaterial. Large quantities of bovine bone are available as a resource in New Zealand due to the presence of an extensive meat industry. Cancellous bone was harvested from within the condyle regions of bovine femoral bone by cutting with either band saw or lapidary saw. Portions of cut cancellous bovine bone were significantly defatted and partially deproteinated through repeated autoclaving. The material was then sintered at 1000°C for 3 hours to give a pristine white sintered cancellous bovine bone (SCBB) material, that although weakened in comparison to its original form, retained the porous trabecular architecture of the original cancellous bone. This material was characterised by means of Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD), while also being subjected to a washing experiment in distilled water with pH monitoring to show that the material was hydroxyapatite (HAp) (Ca10(PO4)6(OH)2) with small quantities of CaO. Scanning Electron Microscopy (SEM) showed that the SCBB material had retained its macroporous architecture, with higher magnification micrographs revealing a microporosity with channels through crystallites of the HAp of approximately 500 – 700 nm in diameter. Organic infiltrating solutions were prepared by dissolving chitosan in hydrochloric acid in addition to calcium phosphate, such as HAp or CaHPO4, to act as a mineral reinforcing material. Due to the limited solubility of HAp, the maximum concentration that could be achieved involving a 50 : 50 w/w combination of chitosan and HAp was 6 g L-1 for both materials in ~ 0.1 mol L-1 HCl. ε Polycaprolactone (PCL) dissolved in tetrahydrofuran (THF) was also trialled as an infiltrating solution, with concentrations up to 14 % w / v dissolved in the THF. Solutions were infiltrated into the porous SCBB material by means of vacuum, vacuum and pressure or a pressure only method. The extent of penetration of the infiltrate into the SCBB was followed by labelling the chitosan molecule with the fluorophore, Fluorescein Isothiocyanate (FITC) and then examining the infiltrated SCBB by fluorescence microscopy. After infiltration into the SCBB material, chitosan and mineral reinforcing were precipitated by an increase in pH. Several methods for increasing solution pH were trialled, including; the addition of urea into the infiltrating solution with subsequent thermal hydrolysis, the catalysis of urea by urease, and treatment with ammonia gas. By products and excess ammonia were shown to be able to be removed from the infiltrated SCBB by repeated washing in water and buffer solution. Mechanical testing on the infiltrated SCBB material was carried out by compression testing on an Instron materials testing instrument. Due to the inherent variability in the density and strength of the starting SCBB material, a statistical approach was required. Multiple samples were used and values for ultimate stress, modulus and a modified toughness measurement obtained from the mechanical testing for non-infiltrated SCBB samples were compared against infiltrated samples. SCBB samples infiltrated with a chitosan / CaHPO4 infiltrate displayed an improvement in ultimate stress, while samples infiltrated with PCL showed an overall increase in modulus. Finally, biocompatibility of the SCBB samples infiltrated with chitosan based infiltrates was tested using L929 fibroblast cell culture testing and a Hen’s Egg Test - Chorioallantoic Membrane (HET-CAM) test. Materials with low cytotoxic response were produced when sufficient washing and buffer treatment was employed after infiltration. This research proved that SCBB could be successfully infiltrated with an organic / mineral composite matrix, which was capable of modifying the mechanical properties of the SCBB, while displaying positive biocompatibility potential.

year: 2010

title: Nitrogen inputs and outputs for New Zealand at national and regional scales: Past, present and future scenarios

authors: Parfitt, R. L.

subjects: ammonia

abstract: The Nanjing Declaration on Nitrogen Management calls for national governments to optimise N management by several strategies including assessment of N cycles. In New Zealand, reactive N continues to be added to the environment mainly by biological N fixation, and increasingly from N fertiliser additions. Here, we extend our work on N budgets in 2001/02 for New Zealand (267 000 km²), at both national and regional scales, to 1861, 2020 and 2050. We first attempt to estimate the N cycle for 1861, the year of the first census and when European settlers were beginning to clear large areas of forest for agriculture in some regions. For the future, we adopt two scenarios: agricultural production increasing at 3% p.a., and a “cap and trade” scheme for N. These scenarios provide instructive results by projecting two very different potential policy directions into the future; they do not represent predictions. The 3% growth scenario warns of ever‐increasing N loads on the environment. The cap and trade scenario (such as may be introduced by regional councils) supports the development of a mechanism by which farmers might constrain N losses without regulations being introduced. These scenarios seek to provide farmers, industry and regulators with an understanding of the large range of future possibilities. This paper highlights the urgency with which primary industry must move away from increased production per se to systems where value is added to products.

text: Nitrogen inputs and outputs for New Zealand at national and regional scales: Past, present and future scenarios The Nanjing Declaration on Nitrogen Management calls for national governments to optimise N management by several strategies including assessment of N cycles. In New Zealand, reactive N continues to be added to the environment mainly by biological N fixation, and increasingly from N fertiliser additions. Here, we extend our work on N budgets in 2001/02 for New Zealand (267 000 km²), at both national and regional scales, to 1861, 2020 and 2050. We first attempt to estimate the N cycle for 1861, the year of the first census and when European settlers were beginning to clear large areas of forest for agriculture in some regions. For the future, we adopt two scenarios: agricultural production increasing at 3% p.a., and a “cap and trade” scheme for N. These scenarios provide instructive results by projecting two very different potential policy directions into the future; they do not represent predictions. The 3% growth scenario warns of ever‐increasing N loads on the environment. The cap and trade scenario (such as may be introduced by regional councils) supports the development of a mechanism by which farmers might constrain N losses without regulations being introduced. These scenarios seek to provide farmers, industry and regulators with an understanding of the large range of future possibilities. This paper highlights the urgency with which primary industry must move away from increased production per se to systems where value is added to products.

year: 2008

title: The general cognitive ability of Maori and European subjects: a comparative study of Queensland test performances and psychometric properties

authors: St George, Ross

abstract: Research was undertaken into the performances of New Zealand Maori and European children on the Queensland Test of Cognitive Abilities. In addition to studying the comparative performances of the two ethnic groups at six age levels, major psychometric properties of the instrument were investigated. Such data have an important bearing upon the issue of psychological equivalence across ethnic or culture group samples.
Seven hundred children (303 Maori and 397 European) aged between eight and a half and fourteen and a half years were tested with the Queensland Test. A small statistically significant ethnic group difference was found favouring the European children. Subsequent analyses indicated that the small difference was of little practical significance. Queensland Test subtest data were also analysed, This indicated that subtest performances were likely to be influenced by subject variables in a manner not necessarily evident in the overall test results. Gender differences in performance on the Pattern Matching Subtest were found and are consistent with other data. 
Queensland Test reliability, validity and item characteristics were researched for the two ethnic groups. 
To obtain test-retest reliability estimates and data on criterion related validity longitudinal studies were undertaken with four ethnically mixed class groups Standard 3 to Form 2). 
The Queensland Test was found to be equally reliable with both ethnic groups although the levels of reliability obtained were not considered entirely satisfactory. 
Validity data indicated that the same general intelligence construct could be employed in the interpretation of Queensland Test results with both European and Maori subjects. Content validity issues were considered and it was argued that in terms of both test content and measurement procedures the Queensland Test should provide an equally valid measure of general intelligence with both groups. 
The criterion related validity coefficients were of approximately the same order for each ethnic group although doubts were expressed about the adequacy of the criteria. Construct validity was investigated by considering the relationship of test performance to age and through factor analytic evidence. The analyses supported the view that the Queensland Test was primarily a measure of the same underlying construct within each ethnic group. In terms of prevailing psychological theories on human intelligence this construct was interpreted as being of a general intelligence nature.
Comparative data on item characteristics did not indicate any marked ethnic group differences. More apparent was the need to restructure particular subtests where items failed to discriminate adequately within both ethnic groups. It was concluded that the weight of evidence was in favour of the psychological equivalence of this ability measure with Maori and European children. 
Data for combined ethnic group samples have been reported, Pooled data were employed in some factor analyses and these supported a general intelligence interpretation of Queensland Test results. Preliminary norms were also derived from combined ethnic group data. 
Findings are discussed in relation to the concept of intelligence and its cross-cultural measurement, other Queensland Test research and recent cross-cultural studies on cognitive abilities in New Zealand.

text: The general cognitive ability of Maori and European subjects: a comparative study of Queensland test performances and psychometric properties Research was undertaken into the performances of New Zealand Maori and European children on the Queensland Test of Cognitive Abilities. In addition to studying the comparative performances of the two ethnic groups at six age levels, major psychometric properties of the instrument were investigated. Such data have an important bearing upon the issue of psychological equivalence across ethnic or culture group samples.
Seven hundred children (303 Maori and 397 European) aged between eight and a half and fourteen and a half years were tested with the Queensland Test. A small statistically significant ethnic group difference was found favouring the European children. Subsequent analyses indicated that the small difference was of little practical significance. Queensland Test subtest data were also analysed, This indicated that subtest performances were likely to be influenced by subject variables in a manner not necessarily evident in the overall test results. Gender differences in performance on the Pattern Matching Subtest were found and are consistent with other data. 
Queensland Test reliability, validity and item characteristics were researched for the two ethnic groups. 
To obtain test-retest reliability estimates and data on criterion related validity longitudinal studies were undertaken with four ethnically mixed class groups Standard 3 to Form 2). 
The Queensland Test was found to be equally reliable with both ethnic groups although the levels of reliability obtained were not considered entirely satisfactory. 
Validity data indicated that the same general intelligence construct could be employed in the interpretation of Queensland Test results with both European and Maori subjects. Content validity issues were considered and it was argued that in terms of both test content and measurement procedures the Queensland Test should provide an equally valid measure of general intelligence with both groups. 
The criterion related validity coefficients were of approximately the same order for each ethnic group although doubts were expressed about the adequacy of the criteria. Construct validity was investigated by considering the relationship of test performance to age and through factor analytic evidence. The analyses supported the view that the Queensland Test was primarily a measure of the same underlying construct within each ethnic group. In terms of prevailing psychological theories on human intelligence this construct was interpreted as being of a general intelligence nature.
Comparative data on item characteristics did not indicate any marked ethnic group differences. More apparent was the need to restructure particular subtests where items failed to discriminate adequately within both ethnic groups. It was concluded that the weight of evidence was in favour of the psychological equivalence of this ability measure with Maori and European children. 
Data for combined ethnic group samples have been reported, Pooled data were employed in some factor analyses and these supported a general intelligence interpretation of Queensland Test results. Preliminary norms were also derived from combined ethnic group data. 
Findings are discussed in relation to the concept of intelligence and its cross-cultural measurement, other Queensland Test research and recent cross-cultural studies on cognitive abilities in New Zealand.

year: 1977