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Fibre, Physical and Mechanical Properties of Ghanaian Hardwoods
Issue:
Volume 3, Issue 3, June 2014
Pages:
25-30
Received:
15 May 2014
Accepted:
3 June 2014
Published:
20 June 2014
Abstract: Wood fibre properties (fiber length, fiber width, cell wall thickness and lumen diameter), physical (oven-dry density) and mechanical properties (modulus of rupture, modulus of elasticity, compression parallel to the grain) of four tropical hardwood species (Terminalia superba (Ofram) and Terminalia ivorensis (Emere), as currently threatened timber species and Quassia undulata ( Hotrohotro) and Recinodendron heudelotii(Wama) as lesser used timber species were investigated to measure and compare their timber properties as potential substitutes. Tree normal trees of each tree species were selected and log samples were cut at the middle portion of stem height to determine the properties. The study revealed that, the densities, compression parallel to grain, modulus of rapture and modulus of elasticity of Ofram and Hortrohotro were not significant, but that of Emere and Wama were significant. The modulus of elasticity of Emere was however not significant. Based on these findings Hortrohotro could be substituted for Ofram and Emere with Wama.
Abstract: Wood fibre properties (fiber length, fiber width, cell wall thickness and lumen diameter), physical (oven-dry density) and mechanical properties (modulus of rupture, modulus of elasticity, compression parallel to the grain) of four tropical hardwood species (Terminalia superba (Ofram) and Terminalia ivorensis (Emere), as currently threatened timber...
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Tree Species Diversity and Dominance in Gelai Forest Reserve, Tanzania
Noah Sitati,
Nathan Gichohi,
Philip Lenaiyasa,
Peter Millanga,
Michael Maina,
Fiesta Warinwa,
Philip Muruthi
Issue:
Volume 3, Issue 3, June 2014
Pages:
31-37
Received:
25 May 2014
Accepted:
9 June 2014
Published:
20 June 2014
Abstract: Tree species diversity and dominance of Gelai Forest Reserve, an isolated montane forest located in an arid area of Northern Tanzania remains unknown. A systematic grid of 390 m x 780 m between 100 plots of 0.02 ha, along nine transects was used during the forest survey. The tree species present, location, diameter above breast height (dbh) and botanical names were recorded including regenerants of tree species and key shrub species. These parameters were then used to determine species diversity index, dominance index, number of tree species regenerants, number of stems per ha and tree basal area per ha. A total of 39 tree species were recorded. The tree species with the highest importance values were Nuxia conjesta (70.7), Olea europaea (44.4) and Crotalaria stulhmanii (40.4). The Simpson index value ranged between 0.0 and 0.034; with Crotalaria stulhmanii having the highest (0.034) index. The tree species diversity index ranged between 0.016 and 0.313. Forest stocking was 377 stems per ha while species basal area ranged between 0.098 m2 and 439 m2 per ha, with Nuxia congesta occupying the highest (439.07 m2 per ha) area and Acacia rovumae the lowest (0.098 m2 per ha), respectively. Seventy nine regenerants were recorded on 9% of the plots. Shrubs, herbs and grasses were found on 55% of the plots mainly without trees dominated by Vernonia galamensis, Leonatis leonorus, Ocimum suave and Solonum incanum. In conclusion, the forest has high tree species diversity which is a good stand characteristic of a natural forest. This survey established a baseline for future monitoring of the forest performance after mitigation of human activities.
Abstract: Tree species diversity and dominance of Gelai Forest Reserve, an isolated montane forest located in an arid area of Northern Tanzania remains unknown. A systematic grid of 390 m x 780 m between 100 plots of 0.02 ha, along nine transects was used during the forest survey. The tree species present, location, diameter above breast height (dbh) and bot...
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Impact of Extraction Methods upon Light Absorbance of Natural Organic Dyes for Dye Sensitized Solar Cells Application
Barness Chirazo Mphande,
Alexander Pogrebnoi
Issue:
Volume 3, Issue 3, June 2014
Pages:
38-45
Received:
2 June 2014
Accepted:
19 June 2014
Published:
30 June 2014
Abstract: Aqueous extraction, cold ethanol, and Soxhlet hot ethanol extraction methods were used to study the general trend in performance of dyes as sensitisers for dye sensitized solar cells (DSSC) from different plants based on optical absorbance, and consequently light harvesting efficiency (LHE). Spathodea campanulata, Thevetia peruviana, Hibiscus sabdariffa, Delonix regia and Acalypha wilkesiana ‘Haleakala’ were used in this study. From the UV/Visible spectrophotometer with the recorded absorption measurements in the range between 300 – 700 nm, the cold ethanol and Soxhlet hot ethanol extracts exhibited LHE between 80 – 100% over 400 ~ 550 nm of visible range, and 40 – 99% for water extracts dyes between 400 – 700 nm. Ethanol extract of Acalypha wilkesiana ‘Haleakala’ had the highest LHE and a widely spread optical spectrum between 400 – 700 nm; it was earmarked as a potential sensitizer candidate for DSSC. The phytochemical screening was applied to detect the presence of anthocyanins, quinones, cuomarines and others in the extracts. Based on the phytochemical screening, there was no appreciable impact of the extraction methods on the presence of the organic compounds relative to individual samples; and also the optical absorption showed that no extraction method was found consistently better than the other in all extracts.
Abstract: Aqueous extraction, cold ethanol, and Soxhlet hot ethanol extraction methods were used to study the general trend in performance of dyes as sensitisers for dye sensitized solar cells (DSSC) from different plants based on optical absorbance, and consequently light harvesting efficiency (LHE). Spathodea campanulata, Thevetia peruviana, Hibiscus sabda...
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