Conflicts in Africa as Compound Disasters: Complex Crises Requiring Comprehensive Responses

This paper reflects on African conflicts as compound disasters. A compound disaster is defined as an emergency situation with adverse consequences resulting from different, but related, disaster-agents (ICLA, 1996). In a natural disaster situation, for instance, an earthquake that is quickly followed by a fire outbreak, gas leakage, the disruption of water supply and the outbreak of water-borne diseases, would be regarded as a compound disaster. Similarly, armed conflicts trigger a chain of consequences. The focus of this paper is the complexity of the consequences and impact of conflicts in Africa. To a lesser extent, the paper looks at the complex causes of the conflicts themselves and, finally, examines challenges with regard to responses.     

Influence of region of production on relative clonal plain tea quality parameters in Kenya

Tea is grown in diverse regions with varying climates. Growers seek high-yielding and superior quality cultivars to improve profitability of the enterprise. A superior quality genotype in one location is assumed to replicate the same attributes when planted in different regions, especially when climatic variations are minimal. Assessment of 20 commercial genotypes under identical management in three locations within Kenya revealed significant (p ? 0.05) plain tea quality differences, demonstrating the need to identify superior quality clones. There were significant (p ? 0.05) differences in the plain tea quality parameters with location of production. It is therefore not possible to produce tea of the same quality even from the same cultivars when the production location is varied. Regression coefficients (r²) of linear correlations of the same parameters at different sites revealed low values that cannot be used to predict quality. This suggests the extents of changes in the individual parameters were different for the same clone in different regions. There were no significant interactions between sites and genotypes in the different plain tea parameters assessed, further showing the changes were not systematic. The results demonstrate that a genotype selected in one site for high quality may not retain the relative quality over other genotypes in new areas. It is necessary to test genotypes in new areas of production to fully evaluate their relative quality potentials.     

Total polyphenols,catechin profiles and antioxidant activity of tea products from purple leaf coloured tea cultivars

Black (aerated) and green (unaerated) tea products, processed from 10 green and 18 purple leaf coloured cultivars of Kenyan origin, and two tea products, from the Japanese cultivars, Yabukita and Yutakamidori, were assayed for total polyphenols (TP) content, individual catechin profiles and in vitro antioxidant capacity (AA). In addition, the phenolic content of the tea products was determined using the Folin–Ciocalteu phenol reagent. Catechin fractions were identified using reverse phase high performance liquid chromatography (HPLC) with a binary gradient elution system.The AA% of the tea products was determined using a 2,2′-diphenyl picrylhydrazyl (DPPH) radical assay method. The results showed that TPs, catechin profiles and antioxidant activities were significantly (p ? 0.05) higher in unaerated than in aerated teas. Tea products from the purple leaf coloured tea cultivars had levels of TPs, total catechin (TC) and antioxidant activities similar to those from the green leaf coloured cultivars, except for teas from the Japanese cultivars that were very low in the assayed parameters. Caffeine content was significantly (p ? 0.05) lower in products from the purple leaf coloured cultivars than in those from the green leaf coloured tea cultivars. Antioxidant activity (%) was higher in tea products from the Kenyan germplasm than in those from the Japanese cultivars. Antioxidant potency of tea products was significantly (r = 0.789⁷, p ? 0.01) influenced by the total anthocyanin content of the purple leaf coloured cultivars. Cyanidin-3-O-glucoside was the anthocyanin most highly correlated with AA% (r = 0.843⁷, p ? 0.01 in unaerated tea). Total catechins in the unaerated products from the green leaf coloured tea cultivars were also significantly correlated with antioxidant capacity (r = 0.818⁷, p ? 0.01). Results from this study suggest that the antioxidant potency of teas is dependent on the predominant flavonoid compound, the type of tea cultivar and the processing method.     

Neural network based model predictive control for a steel pickling process

A multi-layer feedforward neural network model based predictive control scheme is developed for a multivariable nonlinear steel pickling process in this paper. In the acid baths three variables under controlled are the hydrochloric acid concentrations. The baths exhibit the normal features of an industrial system such as nonlinear dynamics and multi-effects among variables. In the modeling, multiple input, single-output recurrent neural network subsystem models are developed using input–output data sets obtaining from mathematical model simulation. The Levenberg–Marquardt algorithm is used to train the process models. In the control (MPC) algorithm, the feedforward neural network models are used to predict the state variables over a prediction horizon within the model predictive control algorithm for searching the optimal control actions via sequential quadratic programming. The proposed algorithm is tested for control of a steel pickling process in several cases in simulation such as for set point tracking, disturbance, model mismatch and presence of noise. The results for the neural network model predictive control (NNMPC) overall show better performance in the control of the system over the conventional PI controller in all cases.     

Early development of a shaftless horizontal axis wind turbine for generating electricity from air discharged from ventilation systems

The air discharged from ventilation systems is a high potential wind resource for generating electricity in countries where wind speed is unreliable or weak, such as in Thailand. The air discharged from ventilation systems produces consistent and high-speed wind when benchmarked against natural wind. However, the limitations of conventional wind turbines are that they have negative impacts on the ventilation system and are inconvenient to install in many areas. The innovative shaftless horizontal axis wind turbine (SHWT) introduced in this article has been designed to close the gap between the wind source and the conventional wind turbines in this process. The concept design shows how it could be mounted next to sources of waste wind, requiring only a small space for installation. An open hole is provided to enable airflow to be discharged into the environment. This SHWT has high market potential for utilizing man-made wind to generate electricity from an alternative source which supports sustainable energy development. The purpose of this study is to demonstrate the concept design of a prototype SHWT used for energy recovery from the discharged air of a ventilation system. How the rotor and stator design of the SHWT optimize wind turbine performance and minimize the negative effects on the ventilation system efficiency are also addressed in this study. The performance of the SHWT is demonstrated in a lab-scale test using the type of propeller fan that is generally applied in many sectors in Thailand. The results showed that the SHWT was successful in generating electricity and produced minimal negative effects on the ventilation system's performance. The maximum power output of the prototype SHWT is 7.4 W at a rotational speed of 1644 rpm using eight sets of magnets and 5.1 m/s wind speed. The maximum wind turbine efficiency is 51%. However, it still requires further optimization to enhance the SHWT performance.     

Characterization of anthocyanins in Kenyan teas: Extraction and identification

Characterization and quantification of anthocyanins in selected tea cultivars processed into black (aerated) and green (unaerated) tea products was carried out in this study. The anthocyanins were extracted from tea products processed from a number of newly bred purple leaf coloured Kenyan tea cultivars (Camellia sinensis) using acidified methanol/HCl (99:1 v/v). Extracted anthocyanins were purified by C₁₈ solid phase extraction (SPE) catridges and characterised by HPLC-UV-Visible. They were identified according to their HPLC retention times, elution order and comparison with authentic standards that were available. Total monomeric anthocyanins were determined by the pH-differential method. Although the tea cultivars gave different yields of anthocyanins, the unaerated (green) teas had significantly (p ? 0.05) higher anthocyanin content than the aerated (black) teas. This was attributed to the degradation of anthocyanins by polyphenol oxidase products (catechin O-quinones) formed during the auto-oxidation (fermentation) process of black tea manufacture. Of the six most common natural anthocyanidins, five were identified in the purified extracts from purple leaf coloured tea, in both aerated (black) and unaerated (green) teas namely; delphinidin, cyanidin, pelargonidin, peonidin and malvidin. The most predominant anthocyanidin was malvidin in both tea products. In addition, two anthocyanins namely, cyanidin-3-O-galactoside and cyanidin-3-O-glucoside were also identified. Tea catechins were also identified in the tea products derived from the purple coloured tea cultivars namely, epigallocatechin (EGC), catechin (+C), epicatechin (EC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG). Correlation between the total catechins versus the total anthocyanins and anthocyanin concentration in unaerated teas revealed significant negative correlations (r = −0.723^∗ and r = −0.743^∗∗, p ? 0.05 and p ? 0.01, respectively). However, in aerated (black) tea the correlations were insignificant (r = −0.182 and r = −0.241, p > 0.05).     

Green tea from purple leaf coloured tea clones in Kenya- their quality characteristics

The Kenyan tea industry wishes to diversify its tea products, and in line with this, anthocyanin – rich teas were developed at the Tea Research Foundation of Kenya. These teas have purple-coloured leaves and the green colour is masked. In total, 12 accessions of the purple leaf coloured teas and 2 standard tea varieties were studied. Clones Hanlu and Yabukita are Chinese and Japanese tea varieties, respectively, known for good green tea, and they were used as reference standards. Little if any research had been done to characterize the quality of these purple leaf coloured teas and this study investigated their total polyphenols (TPP), catechins, caffeine, gallic acid and theanine. These are the major green tea quality parameters. Results showed that the new Kenyan tea clones had higher total polyphenols than had the reference standard tea varieties, which had 17.2% and 19.7% while the lowest among the Kenyan clones was 20.8%. On catechin quality index, K-purple and TRFK 91/1 showed high index values of 15.9 and 13.3, respectively, while clones TRFK 83/1 and 73/5 showed low index values of 0.74 and 1.0, respectively. Hanlu had the highest caffeine level with 2.42% while clones TRFK KS 3, TRFK KS 2 and TRFK 83/1 had relatively high caffeine levels among the purple leaf coloured teas, with 2.33%, 2.22% and 2.21%, respectively. Clone TRFK 73/5 had the lowest caffeine content, with 1.16%. Theanine analysis showed that most purple leaf coloured teas had more theanine than had the reference standard clones, except TRFK 83/1 and K-purple, which were lower than the reference standard clones. The implication of the green tea chemical quality parameters is also discussed. It is concluded that all the studied clones/varieties have above the minimum 14% of total polyphenols. Clones K-purple and TRFK 91/1 showed high green tea quality indices with the latter doubling with high levels of theanine; hence its highly recommended for green tea manufacture.