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Mwasiagi J.I.,Bahir Dar University | Mwasiagi J.I.,Moi University | Mwasiagi J.I.,Donghua University | Yu C.W.,Donghua University | And 4 more authors.
Fibres and Textiles in Eastern Europe | Year: 2014

Hibiscus sabdariffa L. (roselle) is grown in Kenya for its flower and calyx, which are used in the beverage industry. Roselle bast fibre has, however, not been commercially exploited. After harvesting the flowers and calyx the stem together with the bark is used as firewood. This paper reports the characteristics of bast fibres in Hibiscus sabdariffa L. (roselle) grown in Kenya. The bast fibre was characterised by studying its physical and chemical characteristics. The physical characteristics investigated included tensile properties, fineness and surface morphology. An investigation into the type of chemical ingredients present in the fibre was also undertaken. The data obtained in this study indicated that the roselle plant grown in Kenya can produce bast fibres of comparable properties to the kenaf grown in Asian countries. © 2014, Institute of Biopolymers and Chemical Fibres. All rights Reserved. Source

Nalyanya K.M.,Egerton University | Migunde O.P.,Egerton University | Ngumbu R.G.,Egerton University | Onyuka A.,Kenya Industrial Research and Development Institute KIRDI | Rop R.K.,Egerton University
Journal of Thermal Analysis and Calorimetry | Year: 2016

The wide range of applications of collagen-based materials has triggered research interest especially on the effect of environmental factors in that these materials are exposed to during processing and application. As the applications of these collagenous materials continue to increase such as in the field of medicine, more studies are required to gain more insight into their properties. Collagen is a natural biopolymer whose structure is sensitive to ultraviolet (UV) radiations, which alters its mechanical properties. In this study, the influence of artificial UV irradiations, wavelength 254 nm, on the viscoelastic properties and dynamic viscosity of both pickled and tanned hide was investigated by dynamic mechanical analysis. The influence of tanning on the viscoelastic properties and dynamic viscosity was also investigated. Freshly flayed bovine hide was conventionally prepared to pickling stage and split into two identical halves along the backline. One half was tanned using chromium sulfate, while the other half was left at the pickled stage. Samples of appropriate dimensions from both the pickled and tanned hides were cut and irradiated with artificial UV light for different time duration of 6-30 h. The irradiated samples were then analyzed using the DMA in the multi-frequency mode. It was found that irradiation caused an increase in the storage modulus (E′) of pickled hide over the entire irradiation of 6 h followed by consistent decrease up to a duration of 30 h. Tanning caused an increase in tanδ that consistently decreased with the increase in the duration of irradiation. In addition, UV irradiation caused an increase in dynamic viscosity of pickled hide, but a decrease in tanned hide. The results show the predominant elastic nature of bovine hides as indicated by tanδ magnitudes less than a unit. © 2015 Akadémiai Kiadó, Budapest, Hungary. Source

Kosambo-Ayoo L.M.,Kenya Industrial Research and Development Institute KIRDI | Bader M.,University of Hamburg | Loerz H.,University of Hamburg | Becker D.,University of Hamburg
African Journal of Biotechnology | Year: 2011

Sorghum (Sorghum bicolor (L.) Moench) is an important food and fodder crop. Fungal diseases such as anthracnose caused by Colletotrichum sublineolum reduce sorghum yields. Genetic transformation can be used to confer tolerance to plant diseases such as anthracnose. The tolerance can be developed by introducing genes encoding proteins such as chitinases and chitosanases that hydrolyse fungal cell wall. Chitinases endolytically hydrolyse the β-1,4-linkages of chitin whereas, chitosanases hydrolyse the β-1,4-linkages between N-acetyl-D-glucosamine and D-glucosamine residues in a partially acetylated chitin polymer. Particle bombardment was used to genetically transform a sorghum genotype, KAT 412, with chitinase (harchit) and chitosanase (harcho) genes isolated from Trichoderma harzianum. Transgenic sorghum plants, KOSA-1-3, that expressed the two anti-fungal genes were developed. Expression of harchit and harcho in the transformants was confirmed by quantitative real time PCR. In planta and ex planta C. sublineolum infection assays were carried out using one-week old seedlings to determine tolerance to anthracnose. Seedlings from a transgenic line, KOSA-1, were found to be significantly more tolerant to anthracnose than the parent wild type, KAT 412. The Transgenic line was further compared with other wild type sorghum cultivars. The comparison revealed a genotypedependent difference in anthracnose response. The Transgenic line KOSA-1 was found to be more tolerant than the sorghum line SDSH 513 but less tolerant than KAT L5. This demonstrated the existence of genetic diversity, which together with the transgenes, could be utilised to pyramid genes for higher tolerance to anthracnose. The two antifungal genes introduced into sorghum genome could be introgressed into other sorghum lines for fungal diseases resistance. © 2011 Academic Journals. Source

Nalyanya K.M.,Egerton University | Rop R.K.,Egerton University | Onyuka A.,Kenya Industrial Research and Development Institute KIRDI | Migunde P.O.,Egerton University | Ngumbu R.G.,Egerton University
Journal of Applied Polymer Science | Year: 2016

Cowhide, a natural biopolymer of collagen, forms raw material for leather, biomaterials, and food, among others. Thermal and mechanical analysis was done using dynamic mechanical analyzer. Effect of tanning and natural solar radiations on the storage modulus, tan δ, and thermal stability of pickled and tanned cowhides has been investigated in the temperature range of 30-240C. Tanning has been shown to enhance thermal stability and storage modulus. However, tanning decreases its dissipative capability. Thermal stability of both tanned and pickled hide decreased with time of exposure to irradiation. Storage modulus dropped drastically within the initial 6 h of natural solar radiations before rising progressively with the subsequent 12, 18, and 24 h, although still lower than that for nonirradiated sample. Thermal-mechanical analysis proved to be a useful technique for assessing effect of tanning and natural solar radiations on cowhide. © 2015 Wiley Periodicals, Inc. Source

Ogeya M.C.,Kenya Industrial Research and Development Institute KIRDI | Coatanea E.,Aalto University | Medyna G.,Aalto University
Proceedings of the International Conference on Engineering Design, ICED | Year: 2013

This article introduces a design approach integrating early design phase and model based engineering in order to develop innovative biomass gasifier system for rural communities in Africa. The need for such a systemic perspective is imposed by the imbrication of technical, ecological and cultural issues that cannot be ignored while designing new technology. The article proposes an integrated generic design theory approaches to discover and rank by order of importance system's variables and to single out most desired design parameters. A pre-design user requirement assessment was carried out to identify detailed stove's functions. Causal-ordering diagrams sketched for system's modelling. System functions were described graphically and synthesized through simple linear algebraic matrices. Contradictions in system functions were solved using Theory of Inventive Thinking (TRIZ 40). And system's optimization was done through simple Taguchi experimentation method. A two level L8 degree of freedom Taguchi table was used in the experimentation and optimization of the pyrolitic stove. The design approach was exemplified using the case of the "AKIBA" biomass stove. Source

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