Influence Of Density On The Durabilities Of Three Ghanaian Timbers

Stable Food Crops Turning Into Commercial Crops: Case studies of Teff, Wheat and Rice in Ethiopia Review of factors influencing wood durability shows although density varies depending on  trunk position, its role appears controversial for many timber species. Thus, for the first time, the influence of density on the durability of three Ghanaian timbers (Nauclea diderrichii (de Wild.) Merr., Nesogordonia papaverifera (A. Chev.) R. Capuron and Corynanthe pachyceras Welw.) [a Lesser-Utilized-Species (LUS)] is investigated, particularly for tropical species. Stake density was determined using its corrected oven-dry weight and conditioned volume. Extracted density was based on its density and total extractive content determined using 1:2 ethanol-toluene. Mean weight losses (%) for stakes from inner and outer heartwoods (IHW and OHW respectively) of each timber and the middle sapwood (MSW) of C. pachyceras, after exposure to Coriolus versicolor (Linnaeus) Quelet. (a white-rot decay-fungus), were determined and correlated with their densities (unextracted and extracted). Mean densities for N. diderrichii, N. papaverifera and C. pachyceras range between 660-720, 640-700 and 720-820kgm3 respectively for their corresponding IHWs and OHWs, while MSW of C. pachyceras measures 655-794kgm3. Total extractive contents for the heartwoods of the three species range between 13.29-13.96, 10.18-10.65 and 11.03-14.19% respectively, while that of MSW of C. pachyceras is 9.68%. Relationship between densities  at the stem positions and their weight losses resulting from decay by C. versicolor shows weak correlations: R2 = 0.0095, 0.0103 and 0.1251 for N. diderrichii, N. papaverifera and C. pachyceras respectively for their unextracted densities, and R2 = 0.0109, 0.015 and 0.1245 respectively for their extracted densities. Thus, the current study shows density alone has little influence on the decay resistance of the three tropical timbers against bio-deteriogens (e.g.  C. versicolor) and that other factors such as extractives play much role in wood durability

Within-stem denstiy variations of two lesser-utilized timbers and their related primary species

Wood density often influences its quality, marketability and end-use. This paper provides information, for the first time, on the density variation within the stems of two members each of the Rubiaceae and the Tiliaceae from Ghana. From each family, the density at each stem position of a traditional species is compared with that of a related Lesser-Utilized Species (LUS). Density is determinedusing conditioned weight of each block at 20oC and 65%rh and its volume measured using a digital micrometer. Densities ranging from 720-820kg/m3 for Corynanthe pachyceras Welw., and 660-720kg/m3 for Nauclea diderrichii (de Wild.) Merr. (members of the Rubiaceae) were measured. Densities for the two members of the Tiliaceae are lower and range from 295-400kg/m3 for Glyphaeabrevis (Sprengel) Monachino and 640-700kg/m3 for Nesogordonia papaverifera (A. Chev.) R. Capuron. Analysis of variance (ANOVA) is employed to examine differences in densities from differentradial and axial stem positions as well as growth sites for the two (2) LUS. Results have shown that variations in density within the stems exist with density increasing generally from the outer sapwoodto the inner heartwood. However, the trend is sometimes not clear for members of the Tiliaceae (G. brevis and N. papaverifera). It also varies along the stems of the four timbers often decreasing with height from the base to the crown. However, few irregularities also occur along the stems of the LUS. Moreover, this study has shown that growth site influences the within-stem densities of the LUS

Accelerated Field Durability Assessment Of Two Non-Durable Timbers (Ceiba Pentandra (L.) Gaertn. And Celtis Milbraedii Engl.) Impregnated With Natural And Inorganic Preserva-tives

Some timbers have natural resistance against decay. Others are made durable through treatment with preservatives several of which are noxious (e.g. CCA), destroy delicate body organs and are banned in many countries. Eco-friendly but efficient alternatives from organic sources including heartwood extracts of naturally durable plants are being sought. This study compares the effec-tiveness of extracts from two durable timbers (i.e. Tectona grandis L. f. (teak) and Erythro-phleum suaveolens (Guill. & Perr.) Brenan (potrodom) with three notable inorganic preserva-tives (i.e. CCA, Pyrinex 48EC and Creosote) on the field performance of two non-durable tim-bers (i.e. Ceiba pentandra (L.) Gaertn. and Celtis milbraedii Engl.). Mini-stakes (20x2x1cm) were impregnated [at 1.2bars, 123ºC for 3hrs] with 0.5% water-soluble bark extracts of T. gran-dis and E. suaveolens, CCA (0.5%), Pyrinex 48EC (0.5%) and creosote (at manufacturer’s speci-fication), and their retention in each stake determined. The stakes were then buried in the top-soil for 20 weeks. Preservative retention is less for the more viscous creosote than its water-borne counterparts. For all the durability parameters studied (i.e. visual ratings, hardness and mass losses), no significant differences (

Vessel-Fibre Ratio, Specific Gravity And Durability Of Four Ghanaian Hardwoods

Several factors affect wood durability but the influence of anatomy is scarcely studied. Vessels and fibres sampled across and along stems of Milicia excelsa (Welw.) C. C. Berg) (odum), En-tandrophragma cylindricum (Sprague) Sprague (sapele), Terminalia ivorensis A. Chev. (emire) and Antiaris toxicaria Lesch. (kyenkyen) were studied to understand the relationship between their vessel-fibre (V-F) ratios, specific gravities (SGs) and durabilities. Vessels, fibres and their proportions were examined from macerates and T.S. of prepared slides. While the timbers ex-hibit major hardwood cell-types (e.g. vessels, fibres and parenchyma), intra-stem variability ex-ists with more vessels and greater V-F ratios at the crowns and in sapwoods than at the butts and in heartwoods, unlike for fibres. Inter-specific variation also shows A. toxicaria has the greatest vessel content then T. ivorensis, E. cylindricum and M. excelsa, a contrary pattern for fibre con-tents. V-F ratio ranks as: A. toxicaria > E. cylindricum > T. ivorensis > M. excelsa, while SGs are higher in E. cylindricum (667) and M. excelsa (635) than in T. ivorensis (507) and A. toxi-caria (505), which hardly differ from published data. Except for E. cylindricum, butts have the greatest SGs. Correlations between their V-F ratios and SGs are R2 = 34%, 84%, 32% and 1% respectively. Timbers with greatest vessels and V-F ratios but least fibres and SGs have weak relationship and very low durabilities, as in A. toxicaria (R2 = 1%). However, M. excelsa, which has the strongest V-F ratio and SG relationship (R2 = 84%), is very durable.Keywords: Cell type, durability class, macerates, paratracheal parenchyma, vessel- fibre rati

Proximate composition and basic phytochemical assessment of two common varieties of Terminalia catappa (Indian Almond).

Terminalia catappa is a common tree found in Ghana but it is much underutilized. The objective was therefore set to investigate the medicinal and nutritive potential of two common varieties of the plant; the red and yellow varieties. The proximate composition of the nut and pulp of the two varieties were determined using certified methods of the Association of Official Analytical Chemists. Phytochemical screening was also determined using standard screening methods. The red nut had a moisture content of 31.05%; crude fat, 36.9%; protein, 22.19%; ash, 2.76%; carbohydrate, 5.24% and crude fibre, 1.86%. The pulp contained up to 81.96% moisture; 0.04% crude fat; 1.07% protein; 1.47% ash; 14.05% carbohydrates and 1.41% crude fibre. The moisture content constituted 32.06% of the nut of the yellow variety, crude fat was 35.69%; protein, 23.05%; ash, 2.68%; carbohydrate, 4.92% and crude fibre, 1.6%. The pulp of the yellow variety had the proximate composition as: moisture, 84.37%; crude fat, 0.05%; crude protein, 1.54%; ash, 1.62%; carbohydrate, 11.03%; crude fibre, 1.39%. The pulps of both varieties were found to contain saponins, general glycosides, flavonoids, alkaloids, anthraquinones and anthraquinone glycosides. The nut of the yellow variety had terpenoids and steroids present in it while the nut of the red variety had alkaloids present. Statistical analyses carried out showed that there were no significant differences (p≤0.05) between the two varieties based on their proximate composition

Suitability of sawdust from three tropical timbers for wood-cement composites

Construction material rising cost and global demand for economically-sustainable and environmentally-friendly building resources have necessitated the use of sawdust-cement composite. Wood constituents and cement incompatibility hinder its production and need careful selection of the timber. Sawdust suitability from Triplochiton scleroxylon, Entandrophragma cylindricum and Klainedoxa gabonensis for wood-cement composite was determined by identifying their chemical constituents and their composites’ physico-mechanical properties. T. scleroxylon recorded the minimum total extractive (6.12%), lignin (29.89%) and holocellulose (56.38%) and K. gabonensis the maximum (9.31, 31.59 and 57.5% respectively). Ash content was higher for T. scleroxylon (7.6%) but lower for K. gabonensis (1.53%). T. scleroxylon boards were stronger [Modulus of Elasticity (MOE) = 696.1 N/m 2 ] and more moisture-resistant [Moisture Absorption (MA) = 8.8%] than E. cylindricum (MOE = 625.9 N/m 2 ; MA = 9.5%). K. gabonensis boards crushed after manufacturing due to its incompatibility with cement. T. scleroxylon sawdust is suitable for wood-cement composites due to its more compatible chemical constituents (i.e., lower extractive, lignin, holocellulose contents and more ash) and its boards’ excellent physico-mechanical properties than those for the other timbers. Its sawdust-cement composites could be utilized for cladding and walling. The use of sawdust would increase green building resource base and reduce environmental pollution

Efficacy of extractives from parts of Ghanaian pawpaw, avocado and neem on the durability of alstonia

Conventional preservatives are not only toxic to wood bio-deteriorators, but also to humans and animals. In an effort to find preservatives that are non-toxic to humans and animals, efficacy of water extracts of heartwood of Azadirachta indica (Neem) and leaves of Persea americana (avocado) and Carica papaya (pawpaw) at 0.24%, was tested on the durability of wood of Alstonia boonei by pressure impregnation and buried in a termite-prone field for 5 weeks following a modified EN 252 and Gay et al. (1957). Efficacy was tested on the basis of visual durability ratings, percentage hardness and mass losses of impregnated alstonia wood after burial. Though alstonia wood retained pawpaw extract least, pawpaw extract improved the durability of alstonia wood most. Pawpaw extract could be used to improve the durability of alstonia wood better at 0.72% (3x0.24%) and on triple treatment. 83% of Anloga furniture makers who saw the efficacy of pawpaw extract at 0.72% and on triple treatment, showed a high sense of interest in preservative botanical extracts.Key words: Eco-friendly, termite, efficacy, standardization, percentage hardness loss, percentage mass loss, visual durability rating

Sickle cell disease: reappraisal of the role of foetal haemoglobin levels in the frequency of vaso-occlusive crisis

Background: Foetal haemoglobin has been implicated in the modulation of sickle cell crisis. Its level is generally inversely proportional to the severity of sickle cell disease (SCD) for a given sickle cell phenotypes. The main aim of therapy for vaso-occlusive crisis (VOC), which is the hallmark of SCD, is to reduce the chances of sickling through the prevention of polymerization of HbS. One way of preventing this polymerization is by increasing foetal haemoglobin levels.Objectives: To determine the relationship between HbF levels and the frequency of crisis in SCD patients in Ghana.Method: A longitudinal retrospective survey covering a period of 30 months was carried out on adult SCD patients at the Sickle Cell Clinic of the Korle-Bu Teaching Hospital.Results: Eighty-three adults aged 15 to 65 years made up of 40 males and 43 femalea were studied. Analysis of variance (ANOVA) gave significant results in Hb and HbF levels. Higher HbF levels were positively related to less frequent crisis and were significantly high in SCD patients than in controls. HbF effects on the clinical manifestations on SCD were variable.Conclusion: Threshold values of HbF play a role in reducing the frequency of vaso-occlusive crisis in SCD patients and this finding contributes to the body of available literature on SCD severity. However our work does not give the apparent threshold level of helpful HBF Level in SCD.Keywords: Haemoglobin F, Frequency of crisis, sickle cell disease

Low nitric oxide level is implicated in sickle cell disease and its complications in Ghana

Charles Antwi-Boasiako,1 Andrew D Campbell2 1Department of Physiology, School of Biomedical and Allied Health Sciences, College of Health Sciences, University of Ghana, Accra, Ghana; 2Comprehensive Sickle Cell Program Children’s National Medical Center, Division of Hematology, School of Medicine and Health Sciences George Washington University, Washington, DC, USA Background: Nitric oxide (NO) plays a fundamental role in maintaining normal vasomotor tone. Recent clinical and experimental data suggest that NO may play a role in the pathogenesis and therapy of sickle cell disease (SCD). The aim of this study was to determine NO metabolites (NOx) in SCD patients at steady state and in vaso-occlusive crisis (VOC), as well as those with hemolytic clinical sub-phenotype that includes leg ulcers and priapism.Methodology: This was a case–control cross-sectional study conducted on a total of 694 subjects including 148 comparison group HbAA, 208 HbSS SCD patients in steady state, 82 HbSC SCD patients in steady state, 156 HbSS SCD patients in VOC, 34 HbSC SCD patients in VOC, 34 HbSS SCD patients in post VOC, 21 HbSS SCD patients with leg ulcer and 11 HbSS SCD patients with priapism, with age ranging from 15 to 65 years. Laboratory diagnosis of SCD was done at the Sickle Cell Clinic of the Korle-Bu Teaching Hospital. Plasma nitric oxide metabolites were measured using Griess reagent system by ELISA method.Results: Mean NOx of 59.66±0.75 µMol/L in the comparison group was significantly different from those in steady state (P=0.02). During VOC, there was a significant reduction in mean NOx levels to 6.08±0.81 µMol/L (P<0.001). Mean NOx levels were however, significantly higher (50.97±1.68 µMol/L) (P<0.001) in the immediate postcrisis period. The mean NOx levels in the leg ulcer (21.70±1.18 µMol/L) (P<0.001) and priapism (28.97±1.27 µMol/L) (P<0.001) patients were significantly low as compared to the SCD patients in the steady state and comparison group.Conclusion: This study presents the first report on plasma NOx levels in SCD complication in Ghanaian SCD patients and confirms reduced plasma NOx levels in SCD patients in general. Keywords: sickle cell disease, nitric oxide metabolites, vaso-occlusive crisis, priapism, leg ulcer, ELIS