title: A supercapacitor technique for efficiency improvement in linear regulators

authors: Kularatna, Nihal

subjects: engineering

abstract: Paper describes a novel supercapacitor based approach to recover the wasted energy in linear regulators. In this US patent pending technique, a single supercapacitor or an array of supercapacitors could be coupled with a linear series or shunt regulator, where the supercapacitors are charged by the input current of the regulator. This supercapacitor technique, by maintaining the dropout voltage limit before a new capacitor is placed in the series path, recovers the energy and does not use the supercapacitors for voltage conversion. Average efficiency of the overall circuit is improved by a significant amount, while maintaining the useful hall marks of a linear regulator. An example of a 12 to 5 volt proof of concept circuit is detailed with an overall efficiency improvement from 42% to over 78%. The technique is versatile, and, can be developed further to compete with the higher efficiency switching power supplies.

text: A supercapacitor technique for efficiency improvement in linear regulators Paper describes a novel supercapacitor based approach to recover the wasted energy in linear regulators. In this US patent pending technique, a single supercapacitor or an array of supercapacitors could be coupled with a linear series or shunt regulator, where the supercapacitors are charged by the input current of the regulator. This supercapacitor technique, by maintaining the dropout voltage limit before a new capacitor is placed in the series path, recovers the energy and does not use the supercapacitors for voltage conversion. Average efficiency of the overall circuit is improved by a significant amount, while maintaining the useful hall marks of a linear regulator. An example of a 12 to 5 volt proof of concept circuit is detailed with an overall efficiency improvement from 42% to over 78%. The technique is versatile, and, can be developed further to compete with the higher efficiency switching power supplies.

year: 2009

title: The Molecular Weight Characterisation of Pinus radiata Bark Condensed Tannins

authors: Bogun, Ben Rowan

subjects: condensed tannins

abstract: Crude condensed tannins extracted from Pinus radiata bark (sourced from Tokoroa) with various solvents (Hot water (HW), methanol/water/acetic acid (MWA), acetone/water (AW) and hot aqueous 2% sulphite/urea solution (SFU)) were subjected to Sephadex LH-20 column chromatography to purify the condensed tannins by removing carbohydrate and flavonoid components (crude extracts were approximately 70% condensed tannins). The condensed tannins from the HW and MWA extractions were then fractionated on a Sephadex LH-20 column using a stepwise gradient of methanol, water and acetone to separate the condensed tannins according to molecular weight (MW).  Fractions were collected and pooled to give eight final fractions (HW 1-8 and MWA 1-8). Purified and fractionated condensed tannin fractions were then analysed with a range of techniques including 1H nuclear magnetic resonance (NMR) spectroscopy, acid/phloroglucinol depolymerisation coupled with high performance liquid chromatography (HPLC) with UV and MS detection, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), electrospray ionisation mass spectrometry (ESI-MS) and gel permeation chromatography (GPC).
 
In the MALDI-TOF MS spectrum of the crude extracts the most intense signal was typically the tetramer peak and the decamer was typically the largest oligomer detected.  In the spectra of late-eluting column fractions (i.e. HW and MWA 5-7) oligomers greater than the nonamer (DP up to 14) were detected and the most intense signal was shifted from the tetramer to higher MW oligomers. ESI MS showed itself to be better at analysing small MW condensed tannins. The MS results demonstrated that prior separation of the condensed tannins was effective in improving MS detection of higher MW oligomers. 

The mDP of the crude and fractionated fractions was obtained by depolymerisation/HPLC. The mean degree of polymerisation (mDP) of the purified condensed tannins ranged between 7.3 (AW) and 9.2 (SFU).  The mDP of the fractionated condensed tannins ranged between 2 and 18. The depolymerisation/HPLC results of the fractionated condensed tannins were used to construct a GPC calibration curve of condensed tannin MW versus GPC retention time. To identify the GPC dimer peak a procyanidin dimer was synthesised by reacting condensed tannins with catechin under acidic conditions. Through the use of various NMR techniques (DEPT135, COSY, HSQC and HMBC experiments) the synthetic dimer was characterised and the 1H and 13C NMR spectra fully assigned.  The GPC calibration curve enabled MW profiles for the HW and MWA 2-8 fractions and crude extracts to be obtained. GPC analysis confirmed the presence of larger oligomers that were not detected by MALDI-TOF MS and ESI MS.  GPC number average MW results were in agreement with the average MW results obtained from depolymerisation/HPLC results.

Pinus radiata bark condensed tannins from two different geographical locations (Golden Downs (Nelson) and Waimate (South Canterbury)) and different tree heights (0, 10 and 20 m) were analysed using the techniques described above to discover if there was any variability between samples.  Trends that were observed between the different condensed tannins were decreases in condensed tannin yield and mDP as bark was obtained from higher up a tree.  Extracts from New Zealand native bark (totara, rimu and kauri) were also analysed, showing that Rimu was the only bark of these species that contained significant amounts of condensed tannins. Overall this research has provided additional information on the structure and MW of P. radiata condensed tannins.

text: The Molecular Weight Characterisation of Pinus radiata Bark Condensed Tannins Crude condensed tannins extracted from Pinus radiata bark (sourced from Tokoroa) with various solvents (Hot water (HW), methanol/water/acetic acid (MWA), acetone/water (AW) and hot aqueous 2% sulphite/urea solution (SFU)) were subjected to Sephadex LH-20 column chromatography to purify the condensed tannins by removing carbohydrate and flavonoid components (crude extracts were approximately 70% condensed tannins). The condensed tannins from the HW and MWA extractions were then fractionated on a Sephadex LH-20 column using a stepwise gradient of methanol, water and acetone to separate the condensed tannins according to molecular weight (MW).  Fractions were collected and pooled to give eight final fractions (HW 1-8 and MWA 1-8). Purified and fractionated condensed tannin fractions were then analysed with a range of techniques including 1H nuclear magnetic resonance (NMR) spectroscopy, acid/phloroglucinol depolymerisation coupled with high performance liquid chromatography (HPLC) with UV and MS detection, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), electrospray ionisation mass spectrometry (ESI-MS) and gel permeation chromatography (GPC).
 
In the MALDI-TOF MS spectrum of the crude extracts the most intense signal was typically the tetramer peak and the decamer was typically the largest oligomer detected.  In the spectra of late-eluting column fractions (i.e. HW and MWA 5-7) oligomers greater than the nonamer (DP up to 14) were detected and the most intense signal was shifted from the tetramer to higher MW oligomers. ESI MS showed itself to be better at analysing small MW condensed tannins. The MS results demonstrated that prior separation of the condensed tannins was effective in improving MS detection of higher MW oligomers. 

The mDP of the crude and fractionated fractions was obtained by depolymerisation/HPLC. The mean degree of polymerisation (mDP) of the purified condensed tannins ranged between 7.3 (AW) and 9.2 (SFU).  The mDP of the fractionated condensed tannins ranged between 2 and 18. The depolymerisation/HPLC results of the fractionated condensed tannins were used to construct a GPC calibration curve of condensed tannin MW versus GPC retention time. To identify the GPC dimer peak a procyanidin dimer was synthesised by reacting condensed tannins with catechin under acidic conditions. Through the use of various NMR techniques (DEPT135, COSY, HSQC and HMBC experiments) the synthetic dimer was characterised and the 1H and 13C NMR spectra fully assigned.  The GPC calibration curve enabled MW profiles for the HW and MWA 2-8 fractions and crude extracts to be obtained. GPC analysis confirmed the presence of larger oligomers that were not detected by MALDI-TOF MS and ESI MS.  GPC number average MW results were in agreement with the average MW results obtained from depolymerisation/HPLC results.

Pinus radiata bark condensed tannins from two different geographical locations (Golden Downs (Nelson) and Waimate (South Canterbury)) and different tree heights (0, 10 and 20 m) were analysed using the techniques described above to discover if there was any variability between samples.  Trends that were observed between the different condensed tannins were decreases in condensed tannin yield and mDP as bark was obtained from higher up a tree.  Extracts from New Zealand native bark (totara, rimu and kauri) were also analysed, showing that Rimu was the only bark of these species that contained significant amounts of condensed tannins. Overall this research has provided additional information on the structure and MW of P. radiata condensed tannins.

year: 2007

title: Te Whānau Mārama

authors: Tuahine, Hōhepa

subjects: Whānau mārama

abstract: Ko te rā, ko te marama, ko te whetū, ko te auahitūroa, ko te kōtiritiri anō i tapaina e te Māori ko te Whānau Mārama.  Ko te whānau nei ka heke i a Tangotango rāua ko Wainui, he tamariki nā Ranginui rāua ko Papatūānuku, he atua. I whakaako motuhaketia ngā āhuatanga katoa o te Whānau Mārama ki te whare kōkōrangi.  Ko ana whakapapa, ko ana karakia, ko ana waiata, ko ana whakataukī maha.  Ko ngā kai mārō o taua whare wānanga e hoki ana ki te orokotīmatanga mai o Ranginui rāua ko Papatūānuku, heke iho mai ki te tangata me te ao tūroa e mōhiotia ana i tēnei rangi.  He tipua ngā tohunga o te whare kōkōrangi ki te whakamāori i ngā nekehanga me ngā āhuatanga rere kē o te Whānau Mārama nei.  Ka nui ngā tohutohu a te Whānau Mārama e tōnui ai te noho a te Māori ki te whenua.  Heoi anō, kei te āhua tonu o tā te whetū nekehanga i te rangi, kei te āhua tonu o tōna hikohiko mai, otirā kei te āhua tonu o tā te Whānau Mārama taunekeneke atu, taunekeneke mai ki a rātau anō.  Katoa ngā āhuatanga o te Whānau Mārama he mea hei ārahi i te Māori, me te aha, ko ngā mātauranga o te whare nei hei kāpehu ki te tohunga whakatere waka, hei tohu nō Tū ki te ope tauā, hei maramataka ki te ihu oneone, hei kai mārō ki te tauira, hei aha noa atu.  Ko tā tēnei tuhinga, he tūhura i ngā kōrero mō te Whānau Mārama me tana whare wānanga.  Ka titiro ki ngā kōrero kua whakamoanahia i roto i ngā tau maha me te whakamārama i te whakamahia o tēnei mātauranga e kui mā, e koro mā i te wā i a rātau.

text: Te Whānau Mārama Ko te rā, ko te marama, ko te whetū, ko te auahitūroa, ko te kōtiritiri anō i tapaina e te Māori ko te Whānau Mārama.  Ko te whānau nei ka heke i a Tangotango rāua ko Wainui, he tamariki nā Ranginui rāua ko Papatūānuku, he atua. I whakaako motuhaketia ngā āhuatanga katoa o te Whānau Mārama ki te whare kōkōrangi.  Ko ana whakapapa, ko ana karakia, ko ana waiata, ko ana whakataukī maha.  Ko ngā kai mārō o taua whare wānanga e hoki ana ki te orokotīmatanga mai o Ranginui rāua ko Papatūānuku, heke iho mai ki te tangata me te ao tūroa e mōhiotia ana i tēnei rangi.  He tipua ngā tohunga o te whare kōkōrangi ki te whakamāori i ngā nekehanga me ngā āhuatanga rere kē o te Whānau Mārama nei.  Ka nui ngā tohutohu a te Whānau Mārama e tōnui ai te noho a te Māori ki te whenua.  Heoi anō, kei te āhua tonu o tā te whetū nekehanga i te rangi, kei te āhua tonu o tōna hikohiko mai, otirā kei te āhua tonu o tā te Whānau Mārama taunekeneke atu, taunekeneke mai ki a rātau anō.  Katoa ngā āhuatanga o te Whānau Mārama he mea hei ārahi i te Māori, me te aha, ko ngā mātauranga o te whare nei hei kāpehu ki te tohunga whakatere waka, hei tohu nō Tū ki te ope tauā, hei maramataka ki te ihu oneone, hei kai mārō ki te tauira, hei aha noa atu.  Ko tā tēnei tuhinga, he tūhura i ngā kōrero mō te Whānau Mārama me tana whare wānanga.  Ka titiro ki ngā kōrero kua whakamoanahia i roto i ngā tau maha me te whakamārama i te whakamahia o tēnei mātauranga e kui mā, e koro mā i te wā i a rātau.

year: 2016