Pulp and Paper Potentials of Plantain Pseudostem

Homogenized pastes were prepared by adding top-bond white glue as binder to natural fibrous material prepared out of different proportions of bamboo (Ozizentera arbonica), coconut husk (Cocus nucifera), sponge (Acanthus montanus) and wood (cordial). Test samples were prepared from dried cast samples for creep and hardness tests. The results of the analysis were used to determine the material that has close properties to the commercially sourced gasket used as control. The overall assessment of the compatibility and suitability tests confirmed the possible applicability of the materials as gasket in fuel pump, carburetors and in engine oil pumps. The locally produced materials have been tested and found suitable as substitute to the conventional material in this order: Coconut husk mixed with sponge (Ch+Sp) in uniform proportion; Coconut husk (Ch) alone without any mixture, and the mixture of the four fibres (Ba+Ch+Sp+Wd). Keywords: Gasket, Agricultural woody fibres, Creep and Hardness. Journal of Science & Technology (Ghana) Vol. 28 (3) 2008: pp. 159-16

Effects of Cooling Media on the Mechanical Properties and Microstructure of Sand and Die Casting Aluminium Alloys

Die and sand castings are versatile processes capable of being used in mass production of alloys having properties unobtainable by other manufacturing method. In this research, efforts were made to study the effects of cooling media on Aluminium alloy cast. Aluminium scrap (Al – Mg – Si,) were charged into crucible furnace from which as-cast aluminium samples for the experimental work were obtained. The specimens were subjected to hardness test, tensile test and metallographic examination. The results show that samples obtained from air cooled dies had the best mechanical properties and those produce by sand casting had comparable hardness values but lower tensile properties. Other results show that the hardness of cast alloys can be varied by changing the cooling media. Keywords: Die casting, cooling media, aluminium Journal of Science and Technology Vol. 28 (1) 2008 pp. 97-10

Development of Automobile Gaskets from Local Fibres

Moringa oleifera Lam. is a multipurpose tropical dry habitat tree used throughout history for its ‘medicinal\', nutritious, water purification and several other properties. Propagating Moringa spp. by seeds is now becoming difficult due to the over-utilization of the plant, most importantly the seeds, which are currently in greater demand chiefly for oil production used for lubricating and powering machines, and in the cosmetic industry. The other means of breeding is by normal vegetative propagation that employs stem hardwood as long as 2m. This is threatening its production as well since greater amount of propagules is often wasted. Stem maturity, that is, age of cuttings (i.e. hardwood, semi-hardwood and softwood) and stem-cutting length were thus studied to examine their significance on sprouting using a 3 x 4 factorial experiment in Randomized Complete Block Design (RCBD) in two blocks. Split, split-plot analysis was conducted using time as a sub-subplot. Factors examined were the number of sprouted stem-cuttings and shoots as well as shoot length for a period of ten weeks with cuttings planted in natural soil in polythene bags. Hardwood cuttings sprouted best having the highest mean value for the number of shoots produced followed by semi-hardwood cuttings all of length 30cm. Based on the present investigation, it has been found that instead of employing the conventional seeds, which are in short supply and longer stem cuttings for the propagation of Moringa spp. worldwide, hardwoods or semi-hardwoods as short as 30cm can now be employed to ensure their sustainability. Keywords: Hardwood, Moringa oleifera, semi-hardwood, softwood, sprouting, stem-cuttings, vegetative propagation. Journal of Science & Technology (Ghana) Vol. 28 (3) 2008: pp. 152-15

Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background: Detailed, comprehensive, and timely reporting on population health by underlying causes of disability and premature death is crucial to understanding and responding to complex patterns of disease and injury burden over time and across age groups, sexes, and locations. The availability of disease burden estimates can promote evidence-based interventions that enable public health researchers, policy makers, and other professionals to implement strategies that can mitigate diseases. It can also facilitate more rigorous monitoring of progress towards national and international health targets, such as the Sustainable Development Goals. For three decades, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) has filled that need. A global network of collaborators contributed to the production of GBD 2021 by providing, reviewing, and analysing all available data. GBD estimates are updated routinely with additional data and refined analytical methods. GBD 2021 presents, for the first time, estimates of health loss due to the COVID-19 pandemic. Methods: The GBD 2021 disease and injury burden analysis estimated years lived with disability (YLDs), years of life lost (YLLs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries using 100 983 data sources. Data were extracted from vital registration systems, verbal autopsies, censuses, household surveys, disease-specific registries, health service contact data, and other sources. YLDs were calculated by multiplying cause-age-sex-location-year-specific prevalence of sequelae by their respective disability weights, for each disease and injury. YLLs were calculated by multiplying cause-age-sex-location-year-specific deaths by the standard life expectancy at the age that death occurred. DALYs were calculated by summing YLDs and YLLs. HALE estimates were produced using YLDs per capita and age-specific mortality rates by location, age, sex, year, and cause. 95% uncertainty intervals (UIs) were generated for all final estimates as the 2·5th and 97·5th percentiles values of 500 draws. Uncertainty was propagated at each step of the estimation process. Counts and age-standardised rates were calculated globally, for seven super-regions, 21 regions, 204 countries and territories (including 21 countries with subnational locations), and 811 subnational locations, from 1990 to 2021. Here we report data for 2010 to 2021 to highlight trends in disease burden over the past decade and through the first 2 years of the COVID-19 pandemic. Findings: Global DALYs increased from 2·63 billion (95% UI 2·44–2·85) in 2010 to 2·88 billion (2·64–3·15) in 2021 for all causes combined. Much of this increase in the number of DALYs was due to population growth and ageing, as indicated by a decrease in global age-standardised all-cause DALY rates of 14·2% (95% UI 10·7–17·3) between 2010 and 2019. Notably, however, this decrease in rates reversed during the first 2 years of the COVID-19 pandemic, with increases in global age-standardised all-cause DALY rates since 2019 of 4·1% (1·8–6·3) in 2020 and 7·2% (4·7–10·0) in 2021. In 2021, COVID-19 was the leading cause of DALYs globally (212·0 million [198·0–234·5] DALYs), followed by ischaemic heart disease (188·3 million [176·7–198·3]), neonatal disorders (186·3 million [162·3–214·9]), and stroke (160·4 million [148·0–171·7]). However, notable health gains were seen among other leading communicable, maternal, neonatal, and nutritional (CMNN) diseases. Globally between 2010 and 2021, the age-standardised DALY rates for HIV/AIDS decreased by 47·8% (43·3–51·7) and for diarrhoeal diseases decreased by 47·0% (39·9–52·9). Non-communicable diseases contributed 1·73 billion (95% UI 1·54–1·94) DALYs in 2021, with a decrease in age-standardised DALY rates since 2010 of 6·4% (95% UI 3·5–9·5). Between 2010 and 2021, among the 25 leading Level 3 causes, age-standardised DALY rates increased most substantially for anxiety disorders (16·7% [14·0–19·8]), depressive disorders (16·4% [11·9–21·3]), and diabetes (14·0% [10·0–17·4]). Age-standardised DALY rates due to injuries decreased globally by 24·0% (20·7–27·2) between 2010 and 2021, although improvements were not uniform across locations, ages, and sexes. Globally, HALE at birth improved slightly, from 61·3 years (58·6–63·6) in 2010 to 62·2 years (59·4–64·7) in 2021. However, despite this overall increase, HALE decreased by 2·2% (1·6–2·9) between 2019 and 2021. Interpretation: Putting the COVID-19 pandemic in the context of a mutually exclusive and collectively exhaustive list of causes of health loss is crucial to understanding its impact and ensuring that health funding and policy address needs at both local and global levels through cost-effective and evidence-based interventions. A global epidemiological transition remains underway. Our findings suggest that prioritising non-communicable disease prevention and treatment policies, as well as strengthening health systems, continues to be crucially important. The progress on reducing the burden of CMNN diseases must not stall; although global trends are improving, the burden of CMNN diseases remains unacceptably high. Evidence-based interventions will help save the lives of young children and mothers and improve the overall health and economic conditions of societies across the world. Governments and multilateral organisations should prioritise pandemic preparedness planning alongside efforts to reduce the burden of diseases and injuries that will strain resources in the coming decades. Funding: Bill & Melinda Gates Foundation

Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

Background Detailed, comprehensive, and timely reporting on population health by underlying causes of disability and premature death is crucial to understanding and responding to complex patterns of disease and injury burden over time and across age groups, sexes, and locations. The availability of disease burden estimates can promote evidence-based interventions that enable public health researchers, policy makers, and other professionals to implement strategies that can mitigate diseases. It can also facilitate more rigorous monitoring of progress towards national and international health targets, such as the Sustainable Development Goals. For three decades, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) has filled that need. A global network of collaborators contributed to the production of GBD 2021 by providing, reviewing, and analysing all available data. GBD estimates are updated routinely with additional data and refined analytical methods. GBD 2021 presents, for the first time, estimates of health loss due to the COVID-19 pandemic. Methods The GBD 2021 disease and injury burden analysis estimated years lived with disability (YLDs), years of life lost (YLLs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries using 100 983 data sources. Data were extracted from vital registration systems, verbal autopsies, censuses, household surveys, disease-specific registries, health service contact data, and other sources. YLDs were calculated by multiplying cause-age-sex-location-year-specific prevalence of sequelae by their respective disability weights, for each disease and injury. YLLs were calculated by multiplying cause-age-sex-location-year-specific deaths by the standard life expectancy at the age that death occurred. DALYs were calculated by summing YLDs and YLLs. HALE estimates were produced using YLDs per capita and age-specific mortality rates by location, age, sex, year, and cause. 95% uncertainty intervals (UIs) were generated for all final estimates as the 2·5th and 97·5th percentiles values of 500 draws. Uncertainty was propagated at each step of the estimation process. Counts and age-standardised rates were calculated globally, for seven super-regions, 21 regions, 204 countries and territories (including 21 countries with subnational locations), and 811 subnational locations, from 1990 to 2021. Here we report data for 2010 to 2021 to highlight trends in disease burden over the past decade and through the first 2 years of the COVID-19 pandemic. Findings Global DALYs increased from 2·63 billion (95% UI 2·44–2·85) in 2010 to 2·88 billion (2·64–3·15) in 2021 for all causes combined. Much of this increase in the number of DALYs was due to population growth and ageing, as indicated by a decrease in global age-standardised all-cause DALY rates of 14·2% (95% UI 10·7–17·3) between 2010 and 2019. Notably, however, this decrease in rates reversed during the first 2 years of the COVID-19 pandemic, with increases in global age-standardised all-cause DALY rates since 2019 of 4·1% (1·8–6·3) in 2020 and 7·2% (4·7–10·0) in 2021. In 2021, COVID-19 was the leading cause of DALYs globally (212·0 million [198·0–234·5] DALYs), followed by ischaemic heart disease (188·3 million [176·7–198·3]), neonatal disorders (186·3 million [162·3–214·9]), and stroke (160·4 million [148·0–171·7]). However, notable health gains were seen among other leading communicable, maternal, neonatal, and nutritional (CMNN) diseases. Globally between 2010 and 2021, the age-standardised DALY rates for HIV/AIDS decreased by 47·8% (43·3–51·7) and for diarrhoeal diseases decreased by 47·0% (39·9–52·9). Non-communicable diseases contributed 1·73 billion (95% UI 1·54–1·94) DALYs in 2021, with a decrease in age-standardised DALY rates since 2010 of 6·4% (95% UI 3·5–9·5). Between 2010 and 2021, among the 25 leading Level 3 causes, age-standardised DALY rates increased most substantially for anxiety disorders (16·7% [14·0–19·8]), depressive disorders (16·4% [11·9–21·3]), and diabetes (14·0% [10·0–17·4]). Age-standardised DALY rates due to injuries decreased globally by 24·0% (20·7–27·2) between 2010 and 2021, although improvements were not uniform across locations, ages, and sexes. Globally, HALE at birth improved slightly, from 61·3 years (58·6–63·6) in 2010 to 62·2 years (59·4–64·7) in 2021. However, despite this overall increase, HALE decreased by 2·2% (1·6–2·9) between 2019 and 2021. Interpretation Putting the COVID-19 pandemic in the context of a mutually exclusive and collectively exhaustive list of causes of health loss is crucial to understanding its impact and ensuring that health funding and policy address needs at both local and global levels through cost-effective and evidence-based interventions. A global epidemiological transition remains underway. Our findings suggest that prioritising non-communicable disease prevention and treatment policies, as well as strengthening health systems, continues to be crucially important. The progress on reducing the burden of CMNN diseases must not stall; although global trends are improving, the burden of CMNN diseases remains unacceptably high. Evidence-based interventions will help save the lives of young children and mothers and improve the overall health and economic conditions of societies across the world. Governments and multilateral organisations should prioritise pandemic preparedness planning alongside efforts to reduce the burden of diseases and injuries that will strain resources in the coming decades

The effects of isothermal transformation on the fatigue strength of austempered ductile iron

The fatigue strength of austempered ductile irons was studied. Austempering was carried out by initial austenitising at temperatures of 850, 900 and 950°C for 1 hour followed by rapid quenching and holding in a salt bath maintained at temperatures of 280, 300, and 350°C for different time intervals (15,30,60,90 or 120 minutes). Fatigue test was prepared to standard and the number of cycles to failure for each specimen was plotted against the bending stresses for the specimen. Results showed that at low austenitising and low austempering temperatures, the fatigue limits were generally low. Increasing the austenitising temperature to 950°C while maintaining the austempering temperature at 3500C, the fatigue limits of both medium silicon and high silicon alloys increased. The highest fatigue strength 450Nmm-2 was obtained from alloy austenitised at 950°C and austempered at 350°C for 90 minutes. Keywords: fatigue, austempered ductile cast iron Botswana Journal of Technology Vol. 14(2) 2005: 21-2

Effects of heat treatment on deformation characteristics of medium carbon steel

The effects of heat treatment on bending deformation, tensile strength and hardness of RST 37 medium carbon steels were investigated. Steel rod samples of ø12 mm diameter, 100 mm length, and % weight composition of 0.39 wt % C, 0.70 wt % Mn and 0.80 wt % Si and traces of alloying elements were tested. The samples were austenitized at 1123 K, annealed, normalized, quenched and tempered. Mechanical tests conducted on the sam-ples were bending, hardness, ultimate tensile strength, % elongation, breaking strength, yield strength, and yield ratio. The results showed that annealed, normalized and tempered samples exhibited high springback, while the hardened samples showed relatively low springback. As the tensile strength or yield strength increased, ductili-ty or total elongation decreased. The hardness was found to decrease with increasing springback. Journal of Applied Science and Technology Vol. 13 (1 & 2) 2008: pp. 81-8

SC-TRUST: A Dynamic Model for Trustworthy Service Composition in the Internet of Things

© 2021 IEEE - All rights reserved.A future Internet of Things (IoT) will feature a service-oriented architecture consisting of lightweight computing platforms offering individual, loosely-coupled microservices. Often, an end-user will request a bespoke service that will require a composition of two or more microservices offered by different service providers. However, the underlying complexities of soft compositions and the increased security risks are inherent in such a massively decentralised and distributed architecture. The use of trust management to secure the IoT is well studied in the literature. However, there are limitations to its use in service compositions in the IoT. Specifically, transparent (agnostic) trust composition and decomposition remain key problems for this area. A novel model for trustworthy service compositions in the IoT, SC-TRUST, is therefore proposed to deal with these challenges. In this study, the trust properties of service compositions and the effect of service workflows on transparent trust composition and decomposition are investigated. Based on the findings, relevant trust evaluation functions are derived to guide the compositions. SC-TRUST was implemented in a suitable application and its performance, in terms of the utility derived and the trust accuracy, convergence and resiliency, was evaluated. The results show that SC-TRUST improves the quality of service compositions and adequately mitigates trust-related attacks, thus increasing both efficiency and security.Peer reviewedFinal Accepted Versio

Improved mechanical and wear characteristics of hypereutectic aluminium-Silicon alloy matrix composites and empirical modelling of the wear response

For the first time, Silicon Carbide-Zinc Oxide-Graphite reinforced hypereutectic Aluminium–Silicon composites were fabricated by two-step stir casting. The mechanical properties and abrasive wear performance of the composites were experimentally tested. A multilevel factorial design of experiment was conducted to develop a numerical model for predicting the wear rate of composites and optimization of their wear performance as a function of reinforcement characteristics. The results indicated that high content of silicon carbide in the composites superlatively enhanced hardness, tensile strength and fracture toughness by 69.04%, 163.22% and 77.42%, respectively. Correspondingly, high content of graphite indicated superlative wear resistance of 95.87% reduction in wear index while high zinc oxide content revealed enhanced fracture toughness highly comparable with that observed for high silicon carbide content. Nevertheless, in comparison with the monolithic alloy, the trade-offs in the strains-to-fracture of the composites were more pronounced with high silicon carbide content. The developed 2-factor-interaction effects model strongly agrees with the experimental results after passing various model validity tests available in Design Expert Software. It revealed that the composition of reinforcing constituents influenced the model more than the volume fraction, and the interaction between the composition of reinforcement constituents and volume fraction