Isolation and Physico-chemical Properties of Enset Starch

Enset starch (Ensete ventricosum, Musaceae) has been examined for its chemical composition, amylose content and physico-chemical properties. The proximate composition of the starch on dry weight basis was found to be 0.16% ash, 0.25% fat, 0.35% protein, and 99.24% starch. The amylose content was 29%. Scanning electron microscopy (SEM) of enset starch granules showed characteristic morphology that was somewhat angular and elliptical. The starch has normal granule size distribution with a mean particle size of 46μm. It exhibits typical X-ray diffraction pattern of B-type with a distinctive maximum peak at around 17° 2θ Its moisture sorption pattern was similar to that of potato starch but much higher than maize starch. DSC parameters obtained from starch-water mixtures (1:2), namely, the enthalpy of gelatinization (ΔH: 21.6mJmg⁻¹), the onset temperature (T₀: 61.8°C), the peak temperature (T_p: 65.2°C) and the endset temperature (T_e: 71.7°C) were higher than those obtained for potato starch. Brabender viscosity curves of 6% starch paste showed lower peak viscosity (884 BU) than potato starch (1668 BU) but greater than maize starch (302 BU). The breakdown was also lower than potato starch but higher than maize starch. Retrogradation of enset starch was substantially greater than potato starch but less than maize starch.     

A Comparative Study of the use of Enset and Potato Starches in Tablet Formulations

Enset and potato starches have been compared as binding agents and disintegrants in tablets made with paracetamol and chloroquine phosphate. Tablet crushing strengths, friabilities and disintegration times have been measured. The results show that enset starch can be used both as a binding agent and disintegrant. It has a better binding ability than potato starch, giving tablets of lower porosity. However because of this, tablets containing enset starch disintegrate more slowly.     

Some Physico-chemical Properties of Dioscorea Starch from Ethiopia

The chemical composition, amylose content and physio-chemical properties of dioscorea starch (Dioscorea abyssinica, Fam. Dioscoreaceae) from Ethiopia have been investigated. The proximate composition of the starch on dry weight basis was found to be 0.1% ash, 0.5% protein, 1.0% fat and 98.4% starch. The amylose content was 29.7%. Scanning electron microscopy (SEM) showed rounded granules. Particle size analysis revealed granule size distribution with a mean particle size of 29.2 μm. X-ray diffraction study showed a pattern that is typical of B-type with a distinctive maximum peak at around 17° 2 T. The moisture sorption pattern, the swelling power and the solubility values were determined and found to be lower than potato starch. Brabender viscosity curves of 6% starch paste showed a peak viscosity of 781 BU. The breakdown and retrogradation of dioscorea starch were 25 and 501 BU, respectively. DSC parameters of starch-water mixture (1:2) exhibited an onset temperature (T_o) of 64.2°C, a peak temperature (T_p) of 68.2°C and an endset temperature (T_e) of 74.8°C. The enthalpy of gelatinization (ΔH) was 19.2 mJmg⁻¹.     

The Diezma landslide (A-92 motorway,Southern Spain): history and potential for future reactivation

A complete failure analysis of a complex landslide located in Southern Spain (the Diezma landslide) has been undertaken using geotechnical, geophysical and geological data. The triggering factors were a high groundwater level and the reduction in the shear strength parameters of the high-plasticity clay. The 2010 reactivation of the landslide was related to the poor performance of the first line of deep drainage wells, although the second and third line of wells and the anchored pile barrier were effective in preventing the landslide reaching the A-92 motorway. Analysis indicates that further reactivation of the Diezma landslide could take place following a period of heavy rain if the drainage wells are not properly maintained, or if an earthquake of M _w 4.0–5.0 occurs within 25 km of the site.     

Carbon nanotube-textured sand for controlling bioavailability of contaminated sediments

Sand particles textured with multi-walled carbon nanotubes (MWCNTs) can efficiently control the mobility and bioavailability of contaminants found in aquatic sediments. Adsorption measurements for a wide variety of aquatic contaminants (chlorinated hydrocarbons) on MWCNT-textured sand showed orders of magnitude increase in their sorption coefficients compared to traditional materials (sand) when used for physically separating contaminated sediments from overlying water. Molecular dynamics simulations performed on model experimental systems emphasize that the hydrophobic interactions of the MWCNT surfaces play a crucial role in driving the water molecules away, promoting such enhanced contaminant uptake. The MWCNT-textured sand significantly reduced the migration of contaminants from sediments to overlying water and possesses suitable parameters needed for contaminant sequestration and sediment remediation technologies. The single step and scalable procedure described here for synthesizing robust MWCNT-textured sand surfaces will provide important improvements in the field of remediation/aquatic environment restoration technologies.     

Capillary gas chromatography analysis of Ethiopian mustard to determine variability of fatty acid composition

Ethiopian mustard (Brassica carinata A. Braun) is an oil crop grown in Ethiopia. However, the oil is considered low quality, as it contains long chain monounsaturated fatty acids, mainly erucic acid. High erucic acid content is beneficial for the polymer industry, whereas low erucic acid is recommended for food purposes. Both linoleic and linolenic acids are essential fatty acids; however, less than 3% linolenic acid is preferred for oil stability. The objectives of this study were to determine fatty acid composition of Ethiopian mustard to determine the range of genetic diversity for these traits. The genotypes were analysed by capillary gas chromatography (CGC). Twenty‐six fatty acids were identified. In all accessions, the predominant fatty acids were erucic, linoleic, α‐linolenic and oleic, followed by gadoleic and palmitic. To a lesser extent stearic, vaccinic, nervonic and behenic acids were found in all accessions. Significant correlations were found between palmitic acid and stearic acid (positive), between erucic acid and palmitic, stearic, vaccinic, oleic, linoleic and α‐linolenic acids (negative) and eicosenoic acid (positive). Selection and hybridization techniques can be applied to modify the oil content of Ethiopian mustard, considering the variability observed. Copyright © 2004 Society of Chemical Industry     

Forced-convective cooling of citrus fruit: Package design

Optimisation of package design for citrus fruit is required to increase the throughput, by reducing the precooling time, and to enhance fruit quality by providing fast and uniform cooling without inducing chilling injury. The cooling performance of an existing container and of two new containers (Supervent and Ecopack), as stacked on a pallet, was evaluated experimentally and numerically with computational fluid dynamics (CFD). The accuracy of the CFD simulations was confirmed by a good agreement with experiments. The best cooling performance was found for Ecopack, but removing airflow short circuits in this container may enhance the cooling performance even more. Also with respect to uniformity of cooling of the fruit and the magnitude of the convective heat transfer coefficients, in a specific container and between different containers on the pallet, the Ecopack container performed best, followed by the Supervent and the standard container. The new container designs thus clearly showed significant improvements in cooling performance.     

Feedforward operational stiffness modulation and external force estimation of planar robots equipped with variable stiffness actuators

A variable stiffness actuator (VSA) is considered a promising mechanism-based approach for realizing compliant robotic manipulators. By changing the stiffness of each joint, the robot can modulate the stiffness of the entire system to enhance safety and efficiency during physical interaction with other systems. This paper presents a feedforward method to modulate the operational stiffness of a parallel planar robot with multiple VSAs. A VSA utilizing a lever mechanism was developed, clearly presenting its mechanical design and kinematic model details. A computational model of joint-restoring torque was developed based on deformation measurements and hysteresis loop geometry to estimate the applied torque of each joint in real-time. An algorithm was proposed to compute the joint stiffness solution using the robot's kinematic model for modulating the operational stiffness of the parallel robot. Experiments were performed to evaluate the proposed method by comparing the performances of two DOF serial and parallel robot systems. The results demonstrated the capability of the VSA in both feedforward stiffness modulation and external force estimation.

     

Countering the “dam effect”: the case for architecture and governance in developing country health information systems

ABSTRACT

This paper presents a case for enterprise architecture (EA) and IT governance for driving techno-organizational change and coordination of health information systems (HISs) in developing countries. We support our claim with analyses of a large-scale electronic HIS in Ethiopia by tracing the logic of actors’ decisions and conduct within and beyond the organizational boundaries of the Ethiopian Federal Ministry of Health to understand how the information system innovation process is designed, legitimized and imposed by internal and external organizational forces. In the absence of formalized institutional arrangements throughout the HIS development and implementation, an international development agency fills a key gap forming an obligatory passage point which we conceptualize as “the dam effect.” Drawing on actor-network theory, we identify three important implications of EA and IT governance: (1) to help achieve an alignment of interests within the enterprise; (2) to serve as a tool for protecting the interests of the enterprise in external negotiations; and (3) to serve as a pragmatic approach to carrying out techno-organizational change.