title: Purification and preliminary characterization of an extracellular pullulanase from Thermoanaerobium Tok6-B1

authors: Plant, Adrian R.

subjects: biology

abstract: Extracellular pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41) was purified from cell free culture supernatants of Thermoanaerobium Tok6-B1 by ammonium sulphate precipitation, affinity precipitation, gel exclusion and ion exchange chromatography. A final purification factor of over 1600 was achieved. A molecular weight of 120 kD was determined by steric exclusion HPLC. Enzyme activity was specifically directed towards the  1–6 glucosidic linkages of pullulan resulting in 100% conversion to maltotriose and also possessed activity towards  1–4 linkages of starch, amylopectin and amylose producing maltooligosaccharides (DP2-DP4) as products. Maltotetraose was slowly hydrolysed to maltose. Values of K m (% w/v) were 7.3×10⁻³ for pullulan, 2.7×10⁻³ for amylopectin and 4.7×10⁻³ for Lintner's starch. Pullulanase activity was resistant to 6 M urea and was thermostable at temperatures up to 80°C (t 1/2 in the order of hours). Above 80°C thermal denaturation was significant (t 1/2=17 min at 85°C; 5 min at 90°C) but became less so in the presence of substrate (pullulan or starch). Thermostability was greatest at the pH activity optimum (pH 5.5) and was promoted by Ca²⁺ ions.

text: Purification and preliminary characterization of an extracellular pullulanase from Thermoanaerobium Tok6-B1 Extracellular pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41) was purified from cell free culture supernatants of Thermoanaerobium Tok6-B1 by ammonium sulphate precipitation, affinity precipitation, gel exclusion and ion exchange chromatography. A final purification factor of over 1600 was achieved. A molecular weight of 120 kD was determined by steric exclusion HPLC. Enzyme activity was specifically directed towards the  1–6 glucosidic linkages of pullulan resulting in 100% conversion to maltotriose and also possessed activity towards  1–4 linkages of starch, amylopectin and amylose producing maltooligosaccharides (DP2-DP4) as products. Maltotetraose was slowly hydrolysed to maltose. Values of K m (% w/v) were 7.3×10⁻³ for pullulan, 2.7×10⁻³ for amylopectin and 4.7×10⁻³ for Lintner's starch. Pullulanase activity was resistant to 6 M urea and was thermostable at temperatures up to 80°C (t 1/2 in the order of hours). Above 80°C thermal denaturation was significant (t 1/2=17 min at 85°C; 5 min at 90°C) but became less so in the presence of substrate (pullulan or starch). Thermostability was greatest at the pH activity optimum (pH 5.5) and was promoted by Ca²⁺ ions.

year: 1987

title: Used product acquisition, sorting and disposition for circular supply chains: Literature review and research directions

authors: Gunasekara, Lahiru

abstract: The vision of a circular economy (CE) inspires firms, governments, and scholars alike. The transition is underway in both practice and the literature, but success depends on the effective implementation of circular supply chains (CSCs), which encompass acquiring used products, sorting them by type and quality, and deciding which to dispose to various processing options. We review 131 high-impact journal articles on returns acquisition, sorting, and disposition (ASD) over the decade 2012–2021 to assess the current status of ASD research for CSCs and to discuss important research directions for supporting the transition to a CE. Uniquely synthesising the state of the art on all these three overarching decision areas, we find aspects of CSCs prominent in the decade's research agenda, such as closed loop supply chain coordination and ASD for remanufacturing, and highlight growing coverage of behavioural considerations. Research applicability has been constrained by a lack of empirical studies, limited practical validation of mathematical models, a focus on economic objectives, and restrictive modelling assumptions about behaviour and uncertainty in returns. We recommend further research in each part of ASD to facilitate a CSC, and as a whole, for transitioning to a CE. CE concepts such as joint decision-making between product design and returns management, cross-sector collaboration, and product-service systems should inform the agenda for CSC research.

text: Used product acquisition, sorting and disposition for circular supply chains: Literature review and research directions The vision of a circular economy (CE) inspires firms, governments, and scholars alike. The transition is underway in both practice and the literature, but success depends on the effective implementation of circular supply chains (CSCs), which encompass acquiring used products, sorting them by type and quality, and deciding which to dispose to various processing options. We review 131 high-impact journal articles on returns acquisition, sorting, and disposition (ASD) over the decade 2012–2021 to assess the current status of ASD research for CSCs and to discuss important research directions for supporting the transition to a CE. Uniquely synthesising the state of the art on all these three overarching decision areas, we find aspects of CSCs prominent in the decade's research agenda, such as closed loop supply chain coordination and ASD for remanufacturing, and highlight growing coverage of behavioural considerations. Research applicability has been constrained by a lack of empirical studies, limited practical validation of mathematical models, a focus on economic objectives, and restrictive modelling assumptions about behaviour and uncertainty in returns. We recommend further research in each part of ASD to facilitate a CSC, and as a whole, for transitioning to a CE. CE concepts such as joint decision-making between product design and returns management, cross-sector collaboration, and product-service systems should inform the agenda for CSC research.

year: 2023-06-01

title: Ōpōtiki Mai Tawhiti

authors: Maxwell, Te Kahautu

abstract: Ōpōtiki Mai Tawhiti competed at the Mātaatua Regional Kapa Haka Competition 2014 to qualify for the Te Matatini World Championship Kapa Haka Competition 2015, Christchurch. Ōpōtiki Mai Tawhiti placed first overall, 1st mōteatea, 1st, Haka, 1st Whakawātea, 1st Female Leader, 1st Male Leader, 1st Waiata Tira, 1st Te Reo, 1st Original Composition, 1st Costume, 2nd Waiata a Ringa, 2nd, Poi, 2nd Whakaeke.

text: Ōpōtiki Mai Tawhiti Ōpōtiki Mai Tawhiti competed at the Mātaatua Regional Kapa Haka Competition 2014 to qualify for the Te Matatini World Championship Kapa Haka Competition 2015, Christchurch. Ōpōtiki Mai Tawhiti placed first overall, 1st mōteatea, 1st, Haka, 1st Whakawātea, 1st Female Leader, 1st Male Leader, 1st Waiata Tira, 1st Te Reo, 1st Original Composition, 1st Costume, 2nd Waiata a Ringa, 2nd, Poi, 2nd Whakaeke.

year: 2014-02-22