USA soybean germplasm has a narrow genetic base that could be augmented by alleles from the wild species Glycine soja which positively influence agronomic traits. The objective of this study was to identify such alleles for yield and yield component QTL (quantitative trait loci). Two populations of 150 BC2F4 lines were generated from a mating between recurrent parent Glycine max 7499 and donor parent Glycine soja PI 245331 with one line in each population tracing back to the same BC2 plant. Population A was used for the QTL identification analysis and population B was used for the QTL verification test. The population A lines were genotyped at 120 SSR marker loci and one phenotype marker, covering a total map length of 1506 cM in 20 linkage groups with an average interval size of 12.5 cM. There were nine putative QTL significantly (Pandlt;0.0001, LODandgt;3.0) associated with yield and yield component traits across 3 environments. One QTL for seed yield was identified using the combined data; the G. soja allele at satt511 on LG-A1 was associated with increased seed yield (LOD=4.3) with an additive yield effect of 190 235 kg ha-1 depending on the QTL analysis method. The phenotypic variance accounted for by the QTL at satt511 was 12%. This QTL also provided a significant yield increase across environments in the validation population; lines that were homozygous for the G. soja allele at satt511 demonstrated a 6.3% (P=0.037) yield increase over lines that were homozygous for the G. max allele. One seed filling period QTL was identified at satt335 (LOD=4.0) on LG-F with an additive effect of +1 day. This QTL also provided a +1 day additive effect (LOD=3.3) on maturity. These results demonstrate the potential of using exotic germplasm to improve soybean yield.

Switchgrass (Panicum virgatum L.) is an important native warm-season grass for biomass and forage production in the U.S. This research determined the effect of fertilizer type (conventional, manure, and biosolids) and rate on switchgrass biomass yield and forage quality. Fertilizers were added at 0, 33, 67, 100, and 134 kg N ha-1 on established stands of ‘Kanlow’ switchgrass in three northeastern Kentucky counties. Soils across sites ranged from recently cleared forestland (low pH, P, and K) to productive cropland (high pH, P and K). Stands were sampled for forage nutritive value in June, simulating a hay harvest. Nutritive value and biomass yield were sampled in November and March. Results showed a harvest date effect for mean crude protein (CP) of 8.31% in June and 1.16% November and March. There was also a harvest effect for biomass with a mean yield of all harvests of 16.6 MT ha-1 but a N response at only one site. In conclusion, this study suggested that switchgrass may produce adequate nutritive value for dry beef cows in June and fertilizer type and rate may have a limited effect on biomass yields.

Biofuels are becoming more attractive worldwide because of the high energy demands and the fossil fuel resources that are being depleted. Biodiesel is one of the most attractive alternative energy sources to petroleum diesel fuel and it is renewable, non toxic, biodegradable, has low sulphur content and has a high flash point. Biodiesel can be generated from domestic natural resources such as coconuts, rapeseeds, soybeans, sunflower, and waste cooking oil through a commonly used method called transesterification. Transesterification is a reaction whereby oil (e.g. sunflower oil) or fats react with alcohol (e.g. methanol) with or without the presence of a catalyst (e.g. potassium hydroxide) to form fatty acid alkyl esters (biodiesel) and glycerol. The high-energy input for biodiesel production remains a concern for the competitive production of bio-based transportation fuels. However, microwave radiation is a method that can be used in the production of biodiesel to reduce the reaction time as well as to improve product yields. Sunflower oil is one of the biodiesel feedstocks that are used in South Africa and is widely used in cooking and for frying purposes. This study aims to use microwave irradiation to reduce the energy input for biodiesel production. The effect of various reaction variables, including reaction time (10 – 60 seconds), microwave power (300 – 900 watts), catalyst (potassium hydroxide) loading (0.5 – 1.5 wt%) and methanol to oil molar ratio (1:3 – 1:9) on the yield of fatty acid methyl ester (biodiesel) was investigated. The quality of biodiesel produced was analysed by Gas Chromatography (GC), Fourier Transform Infrared Spectroscopy (FTIR) and viscometry. The FTIR results confirmed the presence of functional groups of the FAME produced during transesterification. The results showed that transesterification can proceed much faster under microwave irradiation than when using traditional heating methods. The interaction between the alcohol and oil molecules is significantly improved, leading to shorter reaction times (seconds instead of hours) and improved diesel yields. The highest biodiesel yield obtained was 98% at 1:6 oil-to-methanol molar ratio for both 1 wt% and 1.5 wt% potassium hydroxide (KOH) at a reduced reaction time (30 seconds). The chemical composition of FAME (biodiesel) obtained from different conditions i contained palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and 70% linoleic acid (C18:2). The physical properties (cetane number, viscosity, density and FAME content) of biodiesel produced met the SANS 1935 specification. The energy consumption was reduced from 1.2 kWh with the traditional transesterification to 0.0067 kWh with the microwave transesterification. Microwave irradiation was shown to be effective in significantly lowering the energy consumption for production of biodiesel with good quality for small scale producers. / Thesis (MSc (Engineering Sciences in Chemical Engineering))--North-West University, Potchefstroom Campus, 2013

Biofuels are becoming more attractive worldwide because of the high energy demands and the fossil fuel resources that are being depleted. Biodiesel is one of the most attractive alternative energy sources to petroleum diesel fuel and it is renewable, non toxic, biodegradable, has low sulphur content and has a high flash point. Biodiesel can be generated from domestic natural resources such as coconuts, rapeseeds, soybeans, sunflower, and waste cooking oil through a commonly used method called transesterification. Transesterification is a reaction whereby oil (e.g. sunflower oil) or fats react with alcohol (e.g. methanol) with or without the presence of a catalyst (e.g. potassium hydroxide) to form fatty acid alkyl esters (biodiesel) and glycerol. The high-energy input for biodiesel production remains a concern for the competitive production of bio-based transportation fuels. However, microwave radiation is a method that can be used in the production of biodiesel to reduce the reaction time as well as to improve product yields. Sunflower oil is one of the biodiesel feedstocks that are used in South Africa and is widely used in cooking and for frying purposes. This study aims to use microwave irradiation to reduce the energy input for biodiesel production. The effect of various reaction variables, including reaction time (10 – 60 seconds), microwave power (300 – 900 watts), catalyst (potassium hydroxide) loading (0.5 – 1.5 wt%) and methanol to oil molar ratio (1:3 – 1:9) on the yield of fatty acid methyl ester (biodiesel) was investigated. The quality of biodiesel produced was analysed by Gas Chromatography (GC), Fourier Transform Infrared Spectroscopy (FTIR) and viscometry. The FTIR results confirmed the presence of functional groups of the FAME produced during transesterification. The results showed that transesterification can proceed much faster under microwave irradiation than when using traditional heating methods. The interaction between the alcohol and oil molecules is significantly improved, leading to shorter reaction times (seconds instead of hours) and improved diesel yields. The highest biodiesel yield obtained was 98% at 1:6 oil-to-methanol molar ratio for both 1 wt% and 1.5 wt% potassium hydroxide (KOH) at a reduced reaction time (30 seconds). The chemical composition of FAME (biodiesel) obtained from different conditions i contained palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and 70% linoleic acid (C18:2). The physical properties (cetane number, viscosity, density and FAME content) of biodiesel produced met the SANS 1935 specification. The energy consumption was reduced from 1.2 kWh with the traditional transesterification to 0.0067 kWh with the microwave transesterification. Microwave irradiation was shown to be effective in significantly lowering the energy consumption for production of biodiesel with good quality for small scale producers. / Thesis (MSc (Engineering Sciences in Chemical Engineering))--North-West University, Potchefstroom Campus, 2013

An experimental study was carried out to determine the effect of compaction on arching of wheat flour in storage. A model bin 475 mm in height and 600 mm × 375 mm in cross-section was used to conduct tests and wheat flour at moisture contents (MC) of 8.6% and 14.2% was tested. Direct shear tests were performed to determine the angle of internal friction and cohesion of wheat flour subjected to various compaction pressures. It was observed that the internal friction angles were about the same for the wheat flour at two moisture contents (37.1 vs. 37.5), but cohesion for 14.2% MC was 32% higher than that for 8.6% MC. The flowability of wheat flour decreased with increasing compaction pressure sharply at the initial stage of compaction. Compaction led to a 64% increase in required hopper opening for arching-free flow for flour at 8.6% MC, and 49% at 14.2% MC. However, compaction pressure had little effect on arch formation after it reached above 5 kPa.

Radiation-induced changes in microstructures often lead to significant changes in mechanical properties of alloys used in the construction of nuclear reactors. It is desirable to test small specimens to make efficient use of the small volumes available in test and commercial reactor cores and also because small specimens are less affected by the sometimes steep flux gradients experienced in reactor cores and the sometimes large temperature gradients developed in the specimens from gamma heating. (Continues...).

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Die vorliegende Arbeit untersucht Risikofaktoren und Risikoprämien in Rohstoffmärkten und beinhaltet vier empirische Studien. Die ersten zwei Studien konzentrieren sich dabei auf Risikoprämien von verbundenen Terminmärkten für Elektrizität in Australien. In der dritten Studie wird ein Modell zur Beschreibung von extremen Preissprüngen bei Strom entwickelt. Die vierte Studie untersucht schließlich Risikoprämien in der Convenience Yield auf Rohstoffmärkten. (Für eine detailliertere Beschreibung der einzelnen Studien wird auf die jeweilige englische Zusammenfassung verwiesen.)

Increasing demand from flourishing construction markets led to the successful development of high strength steels (HSS). The new structural steel has exceptional high strength, high fracture toughness, long fatigue life, high corrosion resistance, and better weldability making the material attractive for structural design applications in the modern steel buildings and bridges. With their high strength, typically in the range of 500~700 MPa, and reduced weight/dimensions, it frees imaginations of modern designers and opens up new possibilities. Although HSS cost more, this is more than offset by reduced fabrication and erection costs. The advantage of the intrinsic properties of the HSS makes it possible to achieve successful applications in a cost-effective manner. At present, the Australian steel design standard, AS 4100 (SA, 1998), is limited to conventional low strength steels (LSS) with yield stress less than 450 MPa, (i.e. fy . 450 MPa). As a result steel structural members fabricated from HSS in Australia are usually designed according to overseas specifications, such as AISC-LRFD (AISC, 2003) which allows the design for structures fabricated from HSS materials. However, the design provisions of AISC-LRFD were mainly based on experimental and analytical studies on standard LSS. HSS exhibits mechanical properties that are quite different from conventional LSS. On the other hand, the design procedure and approach of the American specifications (AISC, 2003) are unfamiliar with Australian design engineers, which explains why practising engineers in Australia are reluctant to use AISC-LRFD specification in the design of HSS members. Therefore research into the behaviour of HSS members is essential to address this shortcoming. However, since the use of HSS often leads to smaller sections, hence thinner plates, the elastic and inelastic instability of these thin-walled and HSS members become highly critical. Conservatively, the local instabilities of the constituent plate element interactions in the cross-section have been ignored in the current steel practices. Increasing the slenderness of either plate elements within a cross-section leads to a significant reduction in the section capacity of the structural member. Therefore, the interactive effects between flange and web plate elements have to be considered in the strength, stability and deformation studies of HSS members. Furthermore, the current definitions and values of the plate slenderness limits also vary among major steel design codes (AS4100, 1998; AISC, 2003; EN1993, 2003; BS5950, 2000). The main aim of this research project is to investigate the structural behaviour of Ishaped HSS members subjected to local buckling effects in the elastic and inelastic ranges. For this purpose, it will use advanced numerical analyses and laboratory experiments to study the structural behaviour of these HSS members in compression and bending, respectively. The critical review has found that various inconsistencies among the major steel design specifications (AS4100, 1998; AISC, 2003; EN1993, 2003, BS5950, 2000) in the current practice produce conflicting design predictions of section capacities. The experimental measurements of residual stress distributions have confirmed that the ECCS recommendation (1984) is inappropriate for crosssections fabricated from typical HSS materials (i.e. BISPLATE80). The experimental measurements and numerical studies carried out in this project have produced a better understanding of the structural behaviour of HSS members subjected to local instabilities. The study has enabled to provide a series of proposals for proper assessment of plate slenderness limits for structural members made of HSS materials. It may also enable the inclusion of future version of the AS4100 code for HSS materials to be used in the design of steel building and bridge constructions. It is believed that the use of HSS in building and bridge constructions will increase significantly in the very near future, and to fully-facilitate this, the future versions of national and international steel design specifications must include rational and reliable design rules for members made of all steel grades by including the effects of HSS special characteristics and true interactive local buckling behaviour of HSS members. This research project has contributed towards this.

The introduction of dwarfing genes in wheat and rice enabled significant yield improvements and was later termed the “Green-Revolution”. Dwarfing genes in sorghum have not been accompanied by such increases in grain production. On the contrary, some of the commercially employed dwarfing genes in sorghum have been associated with negative effects on grain yield. A positive correlation between plant height and grain yield was also observed in trial data for a diverse range of hybrids tested within the Queensland Department of Primary Industries and Fisheries Sorghum Breeding Program in north-eastern Australia. No attempts have previously been made to examine the physiological basis of the relationship between plant height and grain yield in sorghum. The dwarfing genes that are commercially used in wheat, Rht-B1 and Rht-D1 (formerly known as Rht1 and Rht2, respectively), on the other hand, have been studied extensively. They have been shown to have substantial and positive effects on grain number and harvest index, while not considerably reducing plant biomass, increasing grain yield. Our objective in this study was to examine the effect of height on the physiological and genetic determinants of growth and yield in sorghum to determine whether there was scope to improve yield by increasing the height of sorghum. A positive correlation between plant height and yield was observed in a population that was fixed for the major dwarfing genes, but showed variation in peduncle and panicle length, which are under control of minor dwarfing genes. To study the effects of a single major dwarfing gene (dw3) on biomass production and grain yield, 2- and 3-dwarf isogenic contrasts were developed in three different genetic backgrounds (R931945-2-2, R955343-1, R955637). In some cases, dw3 led to a significant reduction in plant biomass, which was not sufficiently offset by increase in harvest index to avoid yield reduction. This is contrary to the situation in wheat. The observed reductions in plant biomass in sorghum were associated with reduced tiller number and a reduction in radiation use efficiency (RUE) in the short types. Subsequent experiments suggested that an increase in allocation of biomass to the roots, rather than differences in photosynthetic capacity or respiration, was the main cause for the apparent reduction in RUE. However, due to plant-to-plant variability and the difficulty in accurately measuring root-total biomass ratio, studies with greater replication are required to confirm this hypothesis. It was also found that interactions with genetic background (and environment) moderated the effects of dw3, resulting in smaller height, biomass and grain yield reductions in some isogenic pairs. The effects of dwarfing genes on grain yield therefore need to be assessed separately for different genetic backgrounds. As lodging may be controlled by means other than height reduction (e.g. stay-green), we suggest that yield of standard sorghum types used in industrialised countries may benefit from moderate increases in plant height.