When a permanent magnet is considered for an application, the quantity that quantifies the usability of that material is the magnetic energy product (BH)max. In today’s world, rare earth transition metal permanent magnets like Nd-Fe-B, Sm-Co possesses the maximum magnetic energy product. But still for the industrial application, the ferrite permanent magnets are the primary choice over these rare transition metal magnets. Thus, in the present context, the magnetic energy product of the low cost ferrite system makes it unsuitable for the high magnetic energy application. In this regard, exchange spring magnets which combine the magnetization of the soft phase and coercivity of the hard magnetic phases become important in enhancing the magnetic energy product of the system. In this thesis, the exchange spring behaviour is reported for the first time in hard/soft oxide nanocomposites by microstructural tailoring of hard Barium Ferrite and soft Nickel Zinc Ferrite particles. We have analyzed the magnetization reversal and its correlation with the coercivity mechanism in the Ni0.8Zn0.2Fe2O4/BaFe12O19 exchange spring systems. Using this exchange spring concept, we could enhance the magnetic energy product in Iron Oxide/ Barium Calcium Ferrite nanocomposites compared to the bare hard ferrite by ~13%. The presence of the exchange interaction in this nanocomposite is confirmed by the Henkel plot. Moreover, a detailed Reitveld study, magnetization loop and corresponding variation of the magnetic energy product, Henkel plot analysis and First Order Reversal Curve analysis are performed on nanocomposites of hard Strontium Ferrite and soft Cobalt Ferrite. We have proved the exchange spring behaviour in this composite. In addition, we could successfully tailor the magnetization behaviour of the soft Cobalt Ferrite- hard Strontium Ferrite nanocomposite from non exchange spring behaviour to exchange spring behaviour, by tuning the size of the soft Cobalt Ferrite in the Cobalt Ferrite/Strontium Ferrite nanocomposite. The relative strength of the interaction governing the magnetization process in the composites has been studied using Henkel plot and First Order Reversal Curve method. The FORC method has been utilized to understand the magnetization reversal behaviour as well as the extent of the irreversible magnetization present in both the nanocomposites, having smaller and larger particle size of the Cobalt Ferrite. It has been found that for the all the studied composites, the pinning is the dominant process for magnetization reversal. The detailed structural analysis using thin film XRD, angle dependent magnetic hysteresis and remanent coercivity measurement, coercivity mechanism by micromagnetic analysis and First Order Reversal Curve analysis are performed for thin films of Strontium Ferrite which are grown on c-plane alumina using Pulsed Laser Deposition (PLD) at two different oxygen partial pressures. The magnetic easy directions of both the films lie in the out of plane direction where as the in plane direction corresponds to the magnetic hard direction. Depending on the oxygen partial pressure during deposition, the magnetization reversal changes from S-W type reversal to Kondorsky kind of reversal. Thus, the growth parameter for the Strontium Ferrite single layer which will be used further as a hard layer for realizing oxide exchange spring in oxide multilayer, is optimized. The details of the magnetic and structural properties are analyzed for Nickel Zinc Ferrite thin film grown on (100) MgAl2O4. We have obtained an epitaxial growth of Nickel Zinc Ferrite by tuning the growth parameters of PLD deposition. The ferromagnetic resonance and the angle dependent hysteresis loop suggest that, the magnetic easy direction for the soft Nickel Zinc Ferrite lie in the film plane whereas the out of plane direction is the magnetic hard direction. Using the growth condition of respective Nickel Zinc Ferrite and Strontium Ferrite, we have realized the exchange spring behaviour for the first time in the trilayer structure of SrFe12O19 (20 nm)/Ni0.8Zn0.2Fe2O4(20 nm)/ SrFe12O19 (20 nm) grown on c-plane alumina (Al2O3) using PLD. The FORC distribution for this trilayer structure shows the single switching behaviour, corresponding to the exchange spring behaviour. The reversible ridge measurement shows that the reversible and the irreversible part of the magnetizations are not coupled with each other.

This research study's the use of biological sulfate reduction technologies for the treatment of Sasol Secunda's coal-mine drainage (CMD) using Fischer-Tropsch Reaction Water (FTRW) as a cost-efficient carbon source. The research aims to develop a prototype dynamic model that describes this co-treatment of FTRW and CMD in both a continuously stirred tank reactor (CSTR) biological sulfate reduction (BSR) system and a BSR gas-lift (BSR-GL) integrated system. The BSR-GL system recovers elemental sulfur (S0 ) from the H2S produced and stripped from the BSR unit. Furthermore, this study aims to use the prototype model for a quantitative comparison of the CSTR-BSR and BSR-GL systems. Two bench-scale 5-litre CSTR-BSR and a 20-litre BSR-GL system were operated, under varying feed COD concentrations and hydraulic retention times (HRTs), to generate datasets for use in verification and a rudimentary validation of the prototype model. The BSR-GL integrated system includes 1) a 1-litre H2S gas reactive absorption (ABS) unit utilising an aqueous ferric solution for the recovery of elemental sulfur (S0 ) from sulfide and 2) ferrous biological oxidation reactor to regenerate ferric from the ferrous for re-supply to the ABS unit. The datasets generated in the experimental study allowed for the identification, mathematical modelling and reaction verification of 32 components that interact as reactants and products in 23 reactions observed in the two BSR systems. The prototype model is presented in a mass and charge balanced Gujer matrix that includes, i) 5 SRB mediated processes, ii) 2 liquid-gas mass transfer processes, iii) 3 processes describing the ABS and Fe2+ bio-oxidation units, iv) 4 processes describing sulfide and elemental sulfur oxidation and v) the S0 and poly-sulfide aqueous equilibrium and vi) 9 processes describing death regeneration and BPO hydrolysis. This prototype model was implemented in the DHI WEST® software for initial stage simulation trials. The experimental datasets allowed for the first-stage estimation of the best-fit reaction rate equations and the calibration of the kinetic parameters related to the 23 reactions, using MATLAB® curve fitting toolbox. A pre-processor that describe the pH and equilibrium chemistry of the components of the artificially prepared FTRW+CMD feed mixture batches under varying total concentrations have also been developed in this research. This was done to generated influent file to the DHI WEST® simulations that incorporated the dynamics related to the FTRW+CMD feed mixtures. The sulfate utilisation rate (gSO4 -2 .l-1 .d-1 ) of the GL-BSR and CSTR-BSR systems were compared to determine which system had the best sulfate removal. The results were found to be as follows; a. On comparison it was found that the sulfate substrate utilisation rate for the CSTR_BSR system is 39.28% of that of the BSR-GL_N2 system, where both systems were fed at feed mixture of COD of 2500mgCOD/l, where the COD:SO4 2- was 0.7, b. For the same systems fed a feed mixture of COD at 5000mgCOD/l (COD:SO4 2- = 0.7), the sulfate substrate utilisation rate for the CSTR_BSR system was found to be 17.86% less than that of the BSR_GLN2 system. c. Finally, it was also found that the substrate utilisation rate for the CSTR_BSR system was 30.06% less than that of the BSR_GLN2 system at Se of 4gCOD/l, for both systems fed substrate at 5000mgCOD/l. Thus, it can be concluded that the sulfate substrate utilisation rate for the BSR-GL system is higher than that of the CSTR_BSR system, for systems fed COD feed mixtures at 2.5 or 5gCOD/l where both systems have the same effluent substrate concentrations. However, the difference in the comparative substrate utilisation rate is less at higher feed substrate concentrations. This is the influence of substrate inhibition on the active SRB biomass, which increases with higher effluent substrate concentrations. Finally, this research found that the use of gas-lift reactor technologies is superior to CSTR technologies in the treatment of coal-mine drainage utilising biological sulfate reduction (BSR). The CSTR-BSR system, fed sulfate between 1.6 to 14gSO4 2- /l, produced effluent with high dissolved H2S concentrations, on average 285mgS/l and maximum at >600mgS/l. Releasing this effluent to the environment would be hazardous to aquatic and human health and corrosive to infrastructure. As such, the effluent from the CSTR-BSR system requires further treatment to stabilise the water for any use. The BSR-GL technology allows for the conversion of the H2S produced during BSR reactions to form elemental sulfur, which is a resource recovered from this process, thus complying to the circular economy aim of this study.

The thesis is focused on the theoretical description of the technology of anodizing of aluminium, magnesium, zinc and their alloys. In this work, methods for formation of oxide layers and the used chemical processes are described in detail. The experimental part of this work deals with formation of oxide layers on aluminium, magnesium and zinc of high purity under different conditions. Oxide layers of different thicknesses were created on all three experimental materials. Aluminium was anodized in a bath of 10% H2SO4, magnesium in the bath of 1 mol/dm3 NaOH, and zinc in the bath of 0.5 mol/dm3 NaOH. Processes were carried out at laboratory temperature. On the aluminium, continuous oxide layer was formed. Furthermore rule "312" was verified, that can indicatively be used for calculating the thickness of the resulting oxide layer on the aluminium. When using lower current of 0.08 and 0.2 A for magnesium anodizing, dark colored layer was created comparing to higher current of 0.5 A. More rough appearance of the oxide layer was produced with increasing voltage. Further, it was observed for magnesium that the resulting layer comprises of two sublayers. For zinc, black colored layer was created when the voltage 20 V and current from 0.4 to 0.5 A were used. In the layer, two sublayers were also observed. For lower voltage and current (0.05 A, 0.17 V), formation of the oxide layer on the zinc does not occur, but the crystallographic etching was observed.

The diploma thesis discusses laser cutting of non-ferrous metals using fiber YbYag laser and evaluation of the roughness of cutting edge samples. To manufacture samples of aluminium Al 99,5, deoxidized copper Cu – DHP and brass CuZn37 were used combinations of process parameters according to Taguchi statistical method. Samples were subsequently evaluated, according to the ČSN EN ISO 9013 standard and sorted into roughness cathegories, and by technical and economical evaluation, the most economical process parameter combinations were found. Experimantal part is preceded by description of general methods of cutting, description of laser types, process parameters and their influence on the occurrence of the cutting edge defects and description of roughness measurement and standard ČSN EN ISO 9013.

Industrial ecology is a field of study that encourages the use of closed-loop material cycles to achieve sustainability. Loop closing requires the movement of materials over space, and has long been practiced in the iron and steel industry. Iron and steel (ferrous) scrap generated in the U.S. is increasingly exported to countries in Asia, lengthening the transportation distance associated with closing the loop on the iron and steel life cycle. In order to understand the environmental cost of transporting this commodity, an activity-based maritime transportation model and a theoretical in-land transportation model are used to estimate emissions generated. Results indicate that 10.4 mmt of total emissions were generated, and emissions increased by 136 percent from 2004 to 2009. Increases in the amount of emissions generated are due to increases in the amount of scrap exported and distance it is transported.

Annual bluegrass (Poa annua L.) is the most problematic weed to control in creeping bentgrass (Agrostis stolonifera L.) putting greens.  The objective of this study was to transition a mixed putting green stand of annual bluegrass and creeping bentgrass to a monoculture by using fertilizers and plant growth regulators that selectively inhibit annual bluegrass.  A 25 year old loamy sand rootzone research green, planted with \'Penn-Eagle\' creeping bentgrass, with roughly 45% initial annual bluegrass coverage was utilized.  The biweekly application of ammonium sulfate (4.8 kg ha-1) with treatments of ferrous sulfate at rates of 0, 12.2, 24.4, and 48.8 kg ha-1 and in combination with seaweed extract (12.8 L ha-1) or paclobutrazol (0.37 L ai ha-1 spring and fall; 0.18 L ai ha-1 summer) were applied March to October, 2011 and 2012.  Plots receiving the highest rate of ferrous sulfate resulted in annual bluegrass infestation declines from an early trial amount of 45% to a final average of 20% but also resulted in unacceptable late-summer events of annual bluegrass collapse.  The ferrous sulfate medium rate resulted in a smooth transition from early-trial annual bluegrass infestation of 45% to an end of trial infestation of 20% and had the highest putting green quality.  Previous research has reported that consistent use of paclobutrazol can effectively and safely reduce annual bluegrass infestations.  In this trial annual bluegrass was reduced to 9% infestation after three months of application.  Two unexpected observations from this trial were that ferrous sulfate, applied at medium to high rates, significantly reduced silvery thread moss (Bryum argentum Hedw.) populations and occurrences of dollar spot (Sclerotinia homoeocarpa F. T. Bennett) disease.  Dollar spot control with ferrous sulfate has not previously been reported in the literature, so additional studies were designed to investigate this phenomenon further.  A creeping bentgrass putting green study was conducted to determine if sulfur, iron, or the two combined as ferrous sulfate decreases dollar spot activity.  Ferrous sulfate resulted in the highest turf quality and suppressed S. homoeocarpa infection, even during high disease pressure.  Fe-EDTA suppressed dollar spot infection as well as ferrous sulfate but quality declined to unacceptable levels during the summer, due to Fe-EDTA only.  Sulfur did not affect or increased S. homoeocarpa infection, indicating that a high and frequent foliar rate of iron is responsible for dollar spot control.  An in-vitro study was conducted to determine if agar pH in combination with iron concentrations affects mycelial growth of S. homoeocarpa.  Results from this trial indicated that 5.4 agar pH is an optimal pH for mycelial growth.  The 10 to 100 mg iron kg-1 concentration had little effect on mycelial growth at 5.0 and 5.5 pH, but increased growth at 4.5 and 6.5 pH.  As the iron concentration was increased from 10 to 100 to 1000 mg kg-1, mycelial growth decreased or stopped.  Our final conclusions are that seasonal biweekly foliar applications of the medium rate of ferrous sulfate (24.4 kg ha-1) safely and effectively reduced annual bluegrass infestation out of a creeping bentgrass putting green, while also effectively suppressing silvery thread moss and dollar spot incidence. / Master of Science

Orientador: Ana Carolina Firmino / Resumo: O encharcamento do solo é um problema comum em algumas áreas agricultáveis, inclusive em regiões sob cultivo de soja (Glycine max). Em solos encharcados, ocorre a depleção de O2 do solo pelos microrganismos aeróbicos e plantas, afetando os processos metabólicos e fisiológicos das plantas após sofrerem anoxia no tecido radicular. Outro fator prejudicial neste contexto, é o aumento exponencial da disponibilidade de ferro (Fe) no solo, o que pode resultar na absorção excessiva do Fe pelas plantas. No primeiro experimento, o objetivo foi avaliar a vulnerabilidade do aparato fotossintético e produção de biomassa de duas cultivares de soja no estágio fenológico V2, sob condição hídrica adequada e diferentes níveis de encharcamento do solo associada a uma concentração moderada e duas concentrações tóxicas de Fe. No segundo experimento, o objetivo foi avaliar o comportamento fisiológico e bioquímico da soja cultivar Agroeste 3680 associado ao desenvolvimento das vagens (estágio fenológico R3) sob solo não encharcado e encharcado combinado com uma concentração moderada e duas concentrações tóxicas de Fe. No primeiro experimento, o aparato fotossintético das cultivares de soja responderam diferentemente ao encharcamento e à disponibilidade de Fe no solo. Ambas cultivares foram vulneráveis ao encharcamento de 100% em todas as concentrações Fe, o que resultou em danos acentuados às trocas gasosas, concentração de clorofilas e, consequentemente, levou à diminuição da biomassa seca da part... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Soil waterlogging is a common problem in some agricultural areas, including regions under soybean (Glycine max) cultivation. In waterlogged soils, soil O2 depletion occurs due to aerobic microorganisms and plants, affecting the metabolic and physiological processes of plants after suffering anoxia in their root tissue. Another harmful factor of this situation is the exponential increase in the availability of iron (Fe) in the soil, which may result in excessive Fe uptake by plants. In the first experiment, the objective was to evaluate the vulnerability of the photosynthetic apparatus and biomass production of two soybean cultivars at the phenological stage V2, under optimal water condition and different levels of soil waterlogging, combined with one moderate and two toxic levels of Fe. While in the second experiment, the objective was to evaluate the physiological and biochemical behaviour of soybean cultivar Agroeste 3680, associated with the development of pods (at the phenological stage R3) in non-waterlogged and waterlogged soil, combined with one moderate and two toxic levels of Fe. In the first experiment, the photosynthetic apparatus of the two soybean cultivars responded differently to waterlogging and the availability of Fe in the soil. Both cultivars were vulnerable to waterlogging of 100% at all concentrations Fe, which resulted in damage to gas exchange and chlorophyll levels, and consequently, led to lower shoot and root biomass accumulation. The photosynthetic ... (Complete abstract click electronic access below) / Mestre

Nitrogenase has a central role in the global nitrogen cycle as the enzyme that catalyzes the reduction of atmospheric N2 to NH3. Fixed nitrogen is generally limiting in the environment and in agriculture, so nitrogenase has received much attention as an alternative to nitrogen fertilizers. Characterizing the mechanism of nitrogenase is the goal of this work. The molybdenum nitrogenase enzyme system is comprised of the MoFe protein and the Fe protein. Interactions between these proteins and nucleotides are crucial to catalysis. An important approach to characterize these interactions is to correlate the kinetics of nitrogenase catalysis to a mechanism based on the properties of the nitrogenase components. Ironically, the most successful kinetic model of nitrogenase was devised by R. N. F. Thorneley and D. J. Lowe (T&L) before any crystal structures of nitrogenase were solved. This work critiques the ability of the T&L model to predict nitrogenase catalysis accurately. Several defects in the model are described, but it is qualitatively correct. A literature review and critique leads to the rational design of a new kinetic model of nitrogenase catalysis. Because of its comprehensive scope and superior detail, this model has the potential to describe nitrogenase catalysis quantitatively. However, the development of this model is an ambitious project only begun in this work, step by step. Some of the areas of study include: an analysis of Fe protein reduction by dithionite; the characterization of a form of Fe protein reduced to the all-ferrous [4Fe-4S]0 state with a novel spin S = 0 state by the in vivo reductant flavodoxin; and a novel account of salt effects that weaken the nitrogenase complex to increase the rate of complex dissociation, the rate-limiting step in nitrogenase catalysis.

The main problem of production planning at the enterprise for the processing of non-ferrous metals is a large range of alloys with limited smelting and casting capacities. In this case, it is necessary to connect the cast alloys with the rest of the production in order to balance the capacities of the processing units for rhythmic, uninterrupted and coordinated work. From the validity and accuracy of intra-workshop planning, timeliness, breadth, completeness and reliability of accounting at the enterprise directly depends on the effectiveness and efficiency of its activities in general. Since enterprises for the deep processing of non-ferrous metals have a large number of production sites and technological conversions, for each of which it is necessary to constantly plan production indicators. At the same time, this system should ensure the turnover of metal in a closed metallurgical cycle, prevent the possibility of downtime or overload of existing equipment, personnel, as well as the release of the final product within the time period set by the customer. Thus, the relevance of the research topic lies in the need for continuous planning of production activities that ensure the growth of financial results and reduce the cost of production. / Основной проблемой планирования производства на предприятии по глубокой переработке цветных металлов является большой спектр сплавов с ограниченными плавильно-литейными мощностями. При этом необходимо связать отливаемые сплавы с остальным производством для балансировки мощностей перерабатывающих подразделений для ритмичной, бесперебойной и слаженной работы. От обоснованности и точности внутрицехового планирования, своевременности, широты, полноты и достоверности учета на предприятии напрямую зависит результативность и эффективность её деятельности в целом. Поскольку предприятия по глубокой переработке цветных металлов имеют большое количество производственных участков и технологических переделов, то для каждого из которых необходимо постоянно планировать производственные показатели. При этом данная система должна обеспечить оборачиваемость металла в замкнутом металлургическом цикле, предотвратить возможности простоев или перегрузки имеющегося оборудования, персонала, а также выпуск конечного изделия в установленные заказчиком сроки. Таким образом, актуальность темы исследования заключается в необходимости постоянного планирования производственной деятельности, обеспечивающего рост финансового результата и снижения себестоимости выпускаемой продукции.

Homogeneity of powder blends is an important metric for industrial applications in fortified dairy foods including commercial pediatric nutrition products. Product development practices evaluating physical properties and nutrient stability performance are reliant on blending parameters that deliver a uniform powder at both the pilot and commercial scale. Quantities of individual micronutrients in finished products are particularly critical for formulated infant foods. The two preliminary phases of this study focused on developing a simple, efficient method, specifically for a pilot scale ribbon blender, in which maximum homogeneity in fortified dairy-based powder blends could be reached. In phase one, a red iron oxide pigment powder was mixed throughout a white dairy powder and color homogeneity was measured by comparing L*a*b* color values from powder samples extracted from different areas of the ribbon blender. For phase two, sixteen similar fortified dairy blends were produced with varying ribbon blade shaft rpm, fill level, and blending durations according to a response surface method (RSM). The level of homogeneity of ferrous sulfate in the dairy blend was measured in these fortified mixtures to determine optimal blender parameters. After operating parameters were determined for uniform blending, phase three was enacted using these parameters. A comparison study of nutrient stability in fortified model non-agglomerated powder infant formula (PIF) and agglomerated whey protein concentrate (WPC) powder blends was executed to evaluate the degradative effect of microencapsulated ferrous sulfate (MFS) vs. unencapsulated ferrous sulfate (UFS) in these fortified dairy blends. The nutrient degradation rates of vitamins A, E and C in both PIF and WPC base powder, fortified with either MFS or UFS, were determined and compared during an accelerated eight-week stability study. Using p = 0.05, no statistically significant differences in vitamin degradation rates were observed when comparing independent spray-dried dairy-based blends containing unencapsulated or microencapsulated ferrous sulfate (using an encapsulating composition of 60% stearic acid) during eight weeks of accelerated shelf-life storage conditions (37 °C with a 75% relative humidity, RH). Of note, the degradation rates of vitamins A and E in blends containing PIF and UFS were more rapid than the control and suggestively significantly different (p = 0.07).