This dissertation examines speakers’ production of speech and representational gesture. It utilizes the Repetition Effect as the investigative tool. The Repetition Effect appears to vary by the tendency for some items to shorten when repeating, at least under the condition that speakers can primarily operate by their assumption of the state of knowledge of the listener. In speech, a highly conventionalized form of performance, word duration reduces within the same stretch of coherent discourse; then, it resets in the first mention of a new stretch of coherent discourse regardless of the state of knowledge to the speaker or the listener. Therefore, the Repetition Effect in speech is best analyzed as an automatic behavior triggered by discourse structure, rather than reflecting online changes in word accessibility for either interlocutor, be it for the speaker (Listener-neutral explanation) or for the listener (Listener-modeling explanation). The Repetition Effect in speech production in this dissertation will be accounted for within an exemplar model of the perception/production loop. However, in representational gestures, a much less conventionalized form of performance compared to speech, the Repetition Effect shows a different pattern. When speakers only operate by their assumption of the state of knowledge of the listener, without dynamic, appreciable listener feedback, they steadily reduce most types of representational gesture across tellings. Based on these results, it can be argued that representational gestures primarily serve as a part of speech production, rather than as communicative acts. That is, they are produced without regard to the novelty of the information to the listener, thus, consistent with the Listener-neutral explanation.

The dynamic business environment has prompted the companies to improve their competitiveness in terms of manufacturing efficiencies by exploring faster, better and cheaper modes of product development. In this concern, different approaches are configured such as lean manufacturing, just in time and lead time reduction. The study focuses on a critical investigation into the reduction of Lead Time within discrete manufacturing in Kurdistan region of Iraq and the reasons behind this research, that area has evolved gradually as well as the government has an action plan for national recovery and development of reconstruction, where lead-time has become a major issue in manufacturing industry. Specifically, current research study aims at contributing to the strand by focusing on a critical investigation into the reduction of lead time within discrete manufacturing in Kurdistan region of Iraq, where lead-time has become a major issue in manufacturing industry. Mainly, the study has the goals of developing reliable techniques for reducing the lead time through application of assessment survey, capacity planning and key performance indicators in order to implement and control the manufacturing processes. The rationale behind the present study is consisted of economic development within the region, which has attracted a large number of foreign direct investments, but the expanded lead time is causing hurdles with the lack of a strategic plan for resolving the issue which has not keenly addressed in literature so current study would be beneficial for both the stakeholders such as researchers relying on literature and for practitioners as well. In order to conduct the analysis, current research applies the mixture of quantitative and qualitative research. Specifically, for quantitative analysis, a survey is conducted using questionnaires as data collection tool and SPSS analysis for exploring the cause and effect relationship. Mainly, the data are collected from eight Kurdistan based manufacturers. On the contrary, the qualitative analysis is conducted through the case studies. The development of a comprehensive conceptual framework has been applied for focusing on quick response manufacturing both at batch and mass production level. The framework is a contribution to academic knowledge. Through the outcomes of the study, specific factors which are explored to be the main causes of extension in lead time include ineffective forecasting for material requirements, capacity planning, inaccurate demand analysis, decreased resource efficiency and shipment delays. As the most effective solution to these issues, the findings explained that the lot for lot technique is much better than the fixed period requirements which are mostly used in the Iraq region. Moreover, just in time manufacturing strategy and closed loop capacity is also proven to be fruitful along with the splitting order tactic. It is concluded from the findings of this study that the basic issue lies with management in different areas like in human resource, quality, information acquiring, technological developments and operational efficiency. So, it is recommended to the practitioners to higher efficient management squad at the most basic level to eradicate the root cause of the lead time issue. This research will provide new simple strategies for reducing manufacturing lead-time because this is particularly important, as it can be used to provide guidance to industry practitioners on how to reduce manufacturing lead time.

abstract: Numerous orchestral reductions for piano are plagued by cumbersome passages that impede pianists from delivering phrases with flow and elegance. The vocal works of George Frideric Handel (1685–1759) and Richard Wagner (1813–1883) are among the more unwieldy of these. While arrangers of the piano vocal scores by these two composers admirably include as much orchestration as possible, their efforts often result in writing that is not idiomatic for the piano. The frustrating difficulties in the orchestral reductions of Handel’s “Empio, dirò, tu sei” (Giulio Cesare), his Messiah chorus “For unto us a child is born” as well as Wagner’s aria “Du bist der Lenz” (Die Walküre) all plead for a new, fresh arrangement for the working pianist. Concerning itself with the formation of one’s hands, stamina preservation, and the need to give proper support to the singers, this paper makes examples of these three pieces to document and justify the steps and techniques one may take to customize both these and any variety of orchestral reductions. With great emphasis on the methodology of rewriting operatic and choral orchestral reductions, this document presents newly arranged note–for–note piano vocal scores of the above arias and chorus. By customizing and rewriting complex scores, our partners benefit by singing above the identical accompaniment every time. It is the intent that the collaborative pianist can apply these methods to future rewrites, with the result of producing scores that are conducive to proper technique and flow. / Dissertation/Thesis / D.M.A. Music 2012

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Inicialmente, é feita uma revisão bibliográfica dos principais métodos de obtenção de vanádio metálico, comparando-se os resultados obtidos com os diversos redutores empregados. Também os métodos de purificação usualmente empregados são revistos, e mostra-se a eficácia de alguns deles. A seguir, analisa-se o processo aluminotérmico de obtenção de vanádio metálico a partir de pentóxido de vanádio, compreendendo estudos termodinâmicos, cinéticos e de transporte de calor. É mostrada a influência de diversas variáveis sobre a recuperação do metal. Desenvolve-se na parte experimental o estudo sobre a aluminotermia de pentóxido de vanádio, utilizando-se para isto reatores abertos revestidos com argamassa refratária. Estuda-se a influência das variáveis de processo sobre a recuperação de vanádio, incluindo a adição de fluxantes, a granulometria dos reagentes, o tamanho da carga, a pureza dos reagentes, o uso de excesso de redutor e o modo de ignição da carga. Os resultados experimentais obtidos são apresentados e discutidos. O trabalho apresenta conclusões e sugestões para pesquisas futuras. / A literature survey on the processes of vanadium reduction was carried out having in mind the behavior of the reducing agents used. The refining methods for crude metallic vanadium were also covered in the review. The aluminothermic process for the reduction of vanadium pentoxide was particularly considered. Its thermochemistry features were studied, as well as the heat transfer and the rate phenomena concerning such a reaction system discussed. It was pointed out the effect of the processes parameters on the recovery of metallic vanadium. The experiments were designed to investigate the effects of the harge composition, the purity level of the reactants, the size of the solid particles of the reacting mixture and the ignition method on the recovery of vanadium. The aluminothermic reaction was carried out in an open reaction vessel. The experimental results are presented and discussed. The research work done has reached conclusive trends which allows the proposal for further interesting research.

Este trabalho teve por objetivo estudar a redução por hidrogênio de sínteres produzidos com coque e carvão vegetal. Para isso, foram realizadas sinterizações utilizando 3 tipos de sinter feeds hematíticos. Os sinter feeds foram caracterizados através de análise granulométrica, análise química, difração de raios-X, microscopia óptica e microscopia eletrônica de varredura. Os primeiros ensaios de sinterização visaram a produção de sínter de retorno para as sinterizações posteriores. Misturas adicionando o sinter feed resíduo do processo de pelotização de minérios (SFRP) foram sinterizadas para avaliar o efeito da adição deste subproduto no processo de sinterização. Um teste foi realizado para verificar o efeito da redução de finos presentes no sínter de retorno no processo de sinterização. Foram realizados 6 ensaios de sinterização substituindo o coque por carvão vegetal como combustível do processo. As substituições foram de 0%, 8%, 16%, 25%, 50% e 100%. As amostras com substituições de 0%, 50% e 100% foram reduzidas em termobalança, durante 6 horas, em temperatura de 1000°C, utilizando uma mistura de gases contendo Argônio 10% Hidrogênio. As amostras que apresentaram a melhor e a pior redutibilidade foram estudadas através de cálculos cinéticos, a fim de determinar os mecanismos de reação envolvidos durante a redução dos óxidos. A etapa de caracterização microscópica dos sínteres e reduzidos foi realizada de modo que tornou possível comparar a amostra de sínter antes e após o processo de redução. Os resultados mostraram que, para as misturas produzidas, o sínter fabricado com carvão vegetal diminuiu os índices de produção da sinterização e de resistência do sínter. Contudo, o sínter produzido utilizando somente carvão vegetal como combustível, apresentou maior redutibilidade. Os cálculos cinéticos indicaram, tanto para o sínter produzido com carvão vegetal quanto para o sínter produzido com coque, que o mecanismo controlador nos primeiros instantes (entre 50 e 55 minutos) é a reação química. No sínter produzido com carvão vegetal, o mecânismo muda para o controle misto. No sínter produzido com coque, o mecânismo muda para a difusão. Ensaios interrompendo o tempo de redução em 40min, 80min e 120min (40min + 40min + 40min), foram realizados com a amostra de sínter produzido com 8% de carvão vegetal. Nesta etapa, foi possível identificar os fenômenos de nucleação e crescimento da fase de ferro metálico sobre a estrutura do sínter. / This work aimed to study the sinter reduction by hydrogen produced with charcoal and coke breeze. Three kinds of hematitic sinter feeds were used. The materials were characterized by particle size analysis, chemical analysis, X-ray diffraction optical and scanning electron microscopy. The inicial sintering tests aimed to produce return fines for subsequent sintering. Mixtures adding the sinter feed residue from the pellets process were sintered to evaluate the addition effect of this product in the process of sintering. A test was conducted to verify the effect of elimination of fines present in the sinter return sintering process. Six sintering tests were conducted replacing coke breeze by charcoal as process fuel. The replacements were 0%, 8%, 16%, 25%, 50% and 100%. The samples with substitutions of 0%, 50% e 100% were reduced in thermobalance for 6 hours at a temperature of 1000°C using a blend of gases containing Argon 10% Hydrogen. The samples which presented the best and the worst reducibility were studied through kinect calculations to determine the reaction mechanisms involved during the reduction of oxide. The step of microscopic characterization of reduced sinters was carried out in a way that made possible to compare the sinter sample before and after the process of reduction. The results showed the sinter made with charcoal decrease the sinter rates of production and resistance. However, the sinter made using only charcoal as fuel presented better reducibility. The kinect calculation denotes both for the sinter made with charcoal and sinter made with coke breeze the controlling mechanism in the initial stages (between 50 and 55 minutes) is the chemical reaction. For the sinter produced with charcoal the controlling mechanism switches for mixed control. The sinter produced with coke breeze, the mechanism switches for diffusion. Tests interrupting the reduction time for 40min, 80min e 120min (40min + 40min + 40min) were produced with sinter sample produced with 8% with charcoal. At this stage it was possible to identify the phenomena of nucleation and growth phase of metallic iron on the sinter structure.

Neste trabalho realizaram-se reações de resolução enzimática de alcoóis secundários utilizando a enzima imobilizada lipase de Candida antarctica (NOVOZYME 435). Os alcoóis utilizados foram: (RS)-1-(4-metoxifenil)etanol (1a); (RS)-4-metil-2-pentanol (3a); (RS)-2-metil-3-hexanol (4a); (RS)-5-metil-2-hexanol (5a); (RS)-2-octanol (6a); (RS)-3-heptanol (7a); (RS)-6-metil-5-hepten-2-ol (8a); (RS)-1-octen-3-ol (9a). Todos os alcoóis foram resolvidos pela lipase, com exceção do álcool 4a. Nas resoluções enzimáticas os excessos enantioméricos dos álcoois e acetatos foram superiores a 98 %, havendo a conversão total (50 %) dos enantiômeros S nos respectivos acetatos: (S)-1-acetato-4-metoxifenil (1b); (S)-2-acetato-4-metil-pentano (3b); (S)-2-acetato-5-metil-hexano (5b); (S)-2-acetato-octano (6b); (S)-3-acetato-heptano (7b); (S)-2-acetato-6-metil-5-hepteno (8b); (S)-3-acetato-1-octeno (9b). Realizou-se ainda um estudo biocatalítico envolvendo reações de redução de cetonas com fungos de origem marinha. Foram utilizadas na reduções as cetonas: 4-metoxiacetofenona (1), 1-fenil-etanona (2), 4-metil-2-pentanona (3), 2-octanona (6) e a 6-metil-5-hetpen-2-ona (8) e como biocatalisadores três fungos de origem marinha (Bionectria sp Ce5, Aspergillus sydowii Ce15 e Aspergillus sydowii Ce19). A 4-metoxiacetofenona (1) foi reduzida pelos fungos Bionectria sp Ce5, Aspergillus sydowii Ce15 e Aspergillus sydowii Ce19 com excesso enantiomérico de 98% e rendimento de 65 %. A 2-octanona (6) e a 6-metil-5-hepten-2-ona (8) foram reduzidas pelo fungo A. sydowii Ce15 nos respectivos (S)-álcoois 6a e 8a com pureza enantiomérica > 98 %. Já a 1-fenil-etanona (2) foi reduzida somente pelo fungo Bionectria sp Ce5 com excesso enantiomérico de 50 % e rendimento de 25 %. A 4-metil-2-pentanona (3) não foi reduzida por nenhum dos microrganismos estudados. / This work carried out the enzymatic reactions of alcohols by using a lipase from immobilized Candida Antarctica (NOVOZYME 435). The alcohols used were: (RS)-1- (4-methoxyphenyl) ethanol (1a), (RS)-4-methyl-2-pentanol (3a), (RS)-2-methyl-3- hexanol (4a), (RS)-5-methyl-2-hexanol (5a), (RS)-2-octanol (6a), (RS)-3-heptanol (7a), (RS)-6-methyl-5-hepten-2-ol (8a) and (RS)-1-octen-3-ol (9a). All the alcohols were catalyzed by lipase, except for the alcohol 4a. In this enzymatic resolutions the enantiomeric excesses of alcohols and acetates were more than 98% and total conversions (50%) for enantiomers of the acetates: (R)-1-acetate-4-methoxyphenyl (1b), (R)-2-acetate-4-methyl-pentane (3b), (R)-2-acetate-5-methyl-hexane (5b), (R)-2-acetateoctane (6b), (R)-3-acetate-heptane (7b), (R)-2-acetate-6-methyl-5-hepteno (8b) and (S)- 3-acetate-1-octene (9b). In addition it was studied the biocatalytic reduction of ketones with marine-derived fungi. The ketones used were the 4-metoxyacetophenone (1), 1- phenyl-etanone (2), 4-methyl-2-pentanone (3), 2-octanone (6) and 6-methyl-5-hetpen-2- one (8). The marine-derived fungi used as biocatalysts were Bionectria sp Ce5, Aspergillus sydowii Ce15 and Aspergillus sydowii Ce19. The 4-metoxyacetophenone (1) was reduced by Bionectria sp Ce5 by Aspergillus sydowii Ce15 and Aspergillus sydowii Ce19 in high enantiomeric excess (98% e.e.) and good yield, i.g., 65%. The 2- octanone (6) and 6-methyl-5-hepten-2-one (8) were reduced by A. sydowii Ce15 in the (R)-alcohols 6a and 8a in high enantiomeric purities, > 98% e.e. However the 1-phenyletanone (2) was reduced only by the fungus Bionectria sp Ce5 with enantiomeric excess of 50% and yield of 25%. The 4-methyl-2-pentanone (3) was not reduced by the microorganisms studied.

Neste trabalho realizou-se o primeiro estudo biocatalítico envolvendo reações de redução de cetonas com fungos de origem marinha. Foram utilizadas 7 cetonas comerciais como substratos e 8 fungos derivados marinhos como biocatalisadores. Os fungos foram isolados das esponjas marinhas Geodia corticostylifera (Trichoderma sp Gc1, Penicillium miczynskii Gc5, Aspergillus sydowii Gc12) e Chelonaplysylla erecta (Bionectria sp Ce5, Aspergillus sydowii Ce15, Penicillium raistrickii Ce16 e Aspergillus sydowii Ce19). A redução α-cloroacetofenona (1) foi estudada sob várias condições de reação (mudanças de pH, adição ou ausência de glicose) e o melhor resultado foi com fungo P. miczynskii Gc5, pois se obteve um rendimento isolado de 60 % e excesso enantiomérico de 50 % para a (S)-2-cloro-1-feniletanol (1a). O interessante nestes estudos foi que todos os fungos utilizados na triagem com a α-cloroacetofenona (1) apresentaram seletividade anti-Prelog. Na literatura é comum obter redução enzimática com seletividade Prelog. A α-bromoacetofenona (2) foi biotransformada pelo fungo A. sydowii Ce19 nos correspondentes compostos: (S)-2-bromo-1-feniletanol (2a), (S)-2-cloro-1-feniletanol (1a), enquanto que a α-hidroxiacetofenona (2c), α-clorocetofenona (1) e o epóxido-estireno (2b) foram obtidos por reações não enzimáticas. A p-bromo-α-bromoacetofenona (3) e a p-nitro-α-bromoacetofenona (4) foram totalmente biodegradadas pelo fungo A. sydowii Ce19. A redução biocatalítica da orto-iodoacetofenona (5) e meta-iodoacetofenona (6) com o fungo Trichoderma sp Gc1 forneceu o orto-iodo-1-feniletanol (5a) e o meta-iodo-1-feniletanol (6a) com excelentes excessos enantioméricos (e.e. > 99 %). Ficou comprovado também neste trabalho que os fungos derivados marinhos para promover as reações de redução por biocatálise precisam ser cultivados em água do mar artificial. Enquanto a p-iodoacetofenona (7) produziu o p-iodo-1-feniletanol (7a) com e.e. 48 %. / This work carried out the first biocatalytic study involving reactions of reduction of ketones with marine-derived fungi. In this study were utilized 7 commercial ketones as substrates and 8 marine-derived fungi as biocatalysts. The fungi were isolated from the marine sponges Geodia corticostylifera (Trichoderma sp Gc1, Penicillium miczynskii Gc5, Aspergillus sydowii Gc12) and Chelonaplysylla erecta (Bionectria sp Ce5, Aspergillus sydowii Ce15, Penicillium raistrickii Ce16 and Aspergillus sydowii Ce19). The reduction of 2-chloro-1-phenylethanone was studied under several conditions of reaction (changes of pH, addition or absence of glucose) and the best result was with fungus P. miczynskii Gc5, therefore it was isolated in modest yield of 60% and enantiomeric excess of 50% for the (S)-(+)-2-chloro-1-phenylethanol. The interesting in these studies was that all the fungi utilized in the screening with the 2-chloro-1- phenylethanone presented selectivity anti-Prelog. In the literature is common to obtain enzymatic reduction with Prelog selectivity. The 2-bromo-1-phenylethanone was biotransformated by the fungus A. sydowii Ce19 in the (S)-2-bromo-1-phenylethanol, (S)-2-cloro-1-phenylethanol, whereas the α-hydroxy-acetophenone, 2-chloro-1- phenylethanone and the 2-phenyloxirane were obtained by no enzymatic reactions. The 2-bromo-1-(4-bromophenyl)ethanone and the 2-bromo-1-(4-nitrophenyl)ethanone were biodegraded by the fungus A. sydowii Ce19. The biocatalytic reduction of 1-(2- iodophenyl)ethanol and 1-(3-iodophenyl)ethanol with the fungus Trichoderma sp Gc1 afforded the 1-(2-iodophenyl)ethanol and the 1-(3-iodophenyl)ethanol in excellent enantiomeric excesses (e.e. >99 %). It was verified that the marine-derived fungi must grow in artificial sea water to catalyze the reduction reactions.

Titanium and boron nitride and carbide, titanium diboride were synthesized by carbothermic reduction as single phase as well as mixtures intended to form composite materials. The aim of the project is to study the physical chemistry of carbothermic reduction for the production of pure nonoxide ceramic powders and also for the in-situ formation of ceramic/ceramic partially-densified composites. The thermodynamic and kinetic factors that govern the phase constituents are discussed and the effect of processing parameters on the morphology and extent of reduction are also established. The first part of the present investigation is aimed at the production of titanium nitride, carbonitride and carbide powders and the in-situ formation of TiN/TiC partially-densified composites by the carbothermic reduction of titania in suitable nitriding atmospheres. The investigation includes the aspects of the thermodynamics and kinetics of the nitriding reaction and points out the reaction mechanism by identifying the phase formed after the nitridation process. The microstructures produced after the reduction-nitridation process have been correlated with the thermodynamic and kinetic parameters. The synthesized titanium nitride powder was identified as the carbonitride phase, Ti(CxN1_x), having a range of composition. The rate of reduction of TbO2 was found to be determined by the rate of oxygen diffusion in the sub-oxide lattice and the derived value of activation energy in the temperature range 1473K to 1773K from the Arrhenius plot is 120 kJ-mole-1 of T102. TI305 was found as a high temperature precursor phase for the formation of titanium nitride. The use of iron chloride as catalyst and activated charcoal in the mixtures of oxide increased the yield of titanium nitride phase by enhancing the rate of reduction of titanium oxides. The morphology of titanium carbonitride particles was dependent upon the reactivity of carbon and the temperature. The calculated equilibrium phase fields were found to be in agreement with the experimental data and provide a means to select the variables for the reduction condition for designing a required ceramic microstructure. The microstructure of boron nitrides is closely related to the structural chemistry of carbon and nitriding agent. The main aim of the second part of the project was to synthesize boron nitride and carbide powders and whiskers by carbothermic reduction of boric anhydride (6203) in nitrogen atmosphere and also to understand a relation between the processing parameters and the phases produced. The effect of processing conditions such as the gas composition, reactivity of carbon, reaction temperature and time as well as the composition of starting materials on the synthesis of boron nitride and carbide phases were studied. The reactivity of carbon, B/C ratio and gas composition were the most important variables that determined the formation, structure and morphology of the nitride. During the nitridation process, boron carbide phase also formed and played a significant role. The investigation also reports the evidence for the formation of metastable forms of BN i. e wurtzite and cubic BN. We also report the results of the solubility of nitrogen in C-saturated B4C structure. The third part of the present work is aimed at the production of TiB2 powders. Aspects of the formation of two or three ceramic phase mixtures were also examined together with the relative stability of the single phase mixed diborides with respect to pure diboride phase. The central aim of this part is to establish the mechanism of the synthesis reaction leading to the formation of uniform size of titanium diboride crystals. Titanium boride (TiB2) powder was produced in the powder form by the reduction of ingredient oxides with carbon via a gas-solid phase reaction. For the production of the composite microstructure, the nitrogen partial pressure was found to be the most critical factor. In the composite microstructure, the titanium nitride particles have a submicrometer size whereas the boride particle size is only a few micrometers with predominantly hexagonal morphology. Some calculated equilibrium phase fields have been experimentally verified. The empirical verification is a useful tool to establish the correctness of the calculated phase diagram. The theoretical approach therefore enables to identify the condition for the formation of phase mixtures. The constituent phases depend on the reduction conditions. For example, nitrides in equilibrium with Ti62 can only form above a critical nitrogen partial pressure whereas TiC or B4C form in the inert atmospheres. This result is applicable to all other ceramics. The investigation also shows the viability of production of the composite powder mixture via the oxide co-reduction technique. The synthesis of TIB2/TiN, TiB2ýC, TB2/TN/BN and mixed diboride composites is possible by employing the reduction route.

Iron Fischer-Tropsch (FT) catalysts are typically prepared as iron oxides which are reduced to FT-active iron metal and iron carbide prior to FT synthesis. The iron oxides contain a variety of different chemical and structural promoters to alter FT-activity. Silica is a common structural promoter which stabilises the formation of small crystallites and provides mechanical integrity to the catalyst. However, silica inhibits the reduction of the oxide precursor to the FT-active phases. This ultimately affects catalyst activity and product selectivity. It has been proposed that the silica interacts with the iron to form encapsulating shells of fayalite (Fe2SiO4), or fayalite rafts between the iron oxide and the silica support. In this study, six silica-promoted iron oxide samples were prepared using a simple co-precipitation technique. Samples contain varying amounts of silica, and the samples are named 100/x Fe/SiO2, where x is the weight of silica for 100 weight iron, with x taking on values of 0, 10, 25, 50, 100 and 200. The resulting iron oxides were characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRPD), M¨ossbauer spectroscopy (MS), magnetic susceptibility measurements (MM), Raman spectroscopy, thermal gravimetric analysis (TGA) and nitrogen physisorption. Their reduction in a hydrogen atmosphere was investigated using temperature programmed reduction (TPR), in situ XRPD and TEM. The reduction in hydrogen of 100/0 Fe/SiO2 and 100/10 Fe/SiO2 was also studied using in situ gas flow TEM cells. These cells allow the samples to be studied in the electron microscope at temperature and pressure conditions approaching those experienced in a real reactor environment. In the absence of a silica promoter (100/0 Fe/SiO2), hematite particles are formed with mean particle diameters of 39 ± 12 and 52.7 ± 0.2 nm determined using TEM and XRPD respectively. MM data reveals a magnetic transition (Morin transition) at≈230 K, consistent with a mean particle size of≈50 nm. In a hydrogen atmosphere, the hematite reduces to metallic iron via a two-step process viz. hematite → magnetite → iron. The final iron particles have an average crystallite size of 68.0 ± 0.2 nm. The presence of lower amounts of silica in the samples 100/10 Fe/SiO2, 100/25 Fe/SiO2 and 100/50 Fe/SiO2 results in the formation of silicasubstituted 2-line ferrihydrite particles. Bands in the Raman spectra of these samples shift on increasing silica content, which indicates an increasing number of Fe-O-Si bonds within the ferrihydrite framework. MM reveals typical superparamagnetic (SPM) behaviour above a blocking temperature in the range 39 - 68 K which gives mean particle sizes of 4.2, 3.6 and 3.5 nm for 100/10 Fe/SiO2, 100/25 Fe/SiO2 and 100/50 Fe/SiO2 respectively, in good agreement with particle sizes determined using TEM (3.1±0.4, 2.4±0.3 and 2.4±0.3 nm respectively). MS data at 300 K and 4.2 K were fitted with distributions of ∆EQ and Bhf respectively. The median values of Bhf decrease with increasing silica content, indicating greater degrees of distortion in the Fe3+ environments induced by increased silica substitution. The reduction to metallic iron occurs via a three-step process viz. hematite → magnetite → wu¨stite → iron, with the silica stabilising the wu¨stite phase. The increasing amount of Fe-O-Si bonds on increasing silica content shifts reduction to higher temperatures broadens each reduction step as a result of local Fe-O-Si concentration variations. Fractions of each sample are not completely reduced even at 1000°C, with the relative proportion increasing with increasing silica content. In situ gas flow TEM studies reveal that the mechanism of reduction involves the liberation of atomic iron atoms from the silica-substituted iron oxides which agglomerate and grow into final iron particles. This leaves a poorly crystalline Fe-O-Si bonded framework behind. STEM-EDS and STEM-EELS reveal low concentrations of silicon at the surface of the resulting iron particles, however they do not form encapsulating shells of fayalite as previously suggested. The majority of the silica remains in the Fe-O-Si material which may crystallise into separate fayalite particles at elevated temperature. The presence of silica in high proportions (100/100 Fe/SiO2 and 100/200 Fe/SiO2) results in the formation of a two-phase system consisting of silicasubstituted 2-line ferrihydrite particles which are encapsulated in an ironinfused amorphous silica network. As with the other silica-bearing samples, there is an increase in Fe-O-Si bonds and an increase in the degree of distortion at Fe3+ sites with increasing silica content. The large amount of silica suppresses the blocking temperature of the SPM crystallites. In a hydrogen atmosphere, the reduction to metallic iron follows the same three step process as the other silica-bearing samples. Reduction temperatures are further shifted to higher values and given reduction steps are considerably broader with increasing silica content. The fraction of iron not fully reduced also increases. Iron particle diameters are very small, since encapsulation by the silica matrix prevents growth of particles.