Sistemas de liberação controlada vêm sendo cada vez mais utilizados em diferentes áreas tendo em vista sua aplicabilidade que os tornam uma tecnologia capaz de atender as necessidades econômicas e ambientais uma vez que permitem a utilização de princípios ativos em quantidades precisas e apenas nos locais desejados. Dentre a diversidade de opções de matrizes utilizadas nesses sistemas o poli(álcool vinílico) tem sido bastante empregado e pode ser obtido pela técnica de ciclos térmicos. Azadiractina, um princípio ativo encontrado em óleo de semente de Nim tem sido descrita como repelente de diferentes tipos de insetos e apresenta grande aplicabilidade na agricultura. Com base nas propriedades desse composto, propôs-se o desenvolvimento de um sistema de liberação controlada para combate a pulgas Ctenocephalides felis felis. No presente trabalho, foram realizadas caracterizações físico-químicas das matrizes e dispositivos através de ensaios de fração gel, intumescimento, calorimetria exploratória diferencial e microscopia eletrônica de varredura e caracterizações biológicas quanto à citotoxicidade do óleo de Nim, matrizes e dispositivos e bioensaio para análise do comportamento das pulgas na presença do óleo de Nim. As caracterizações físico-químicas permitiram a escolha da matriz mais adequada para o desenvolvimento do dispositivo. As caracterizações biológicas demonstraram ausência de citotoxicidade do óleo de Nim, das matrizes e dos dispositivos e o bioensaio resultou em 40% de mortalidade das pulgas testadas. Na cinética de liberação, verificou-se que todos os agentes encapsulantes utilizados permitiram a liberação de princípios ativos do óleo de Nim. / Controlled release systems has been increasingly used into different purposes due to its applicability that turns it onto a technology able to supply economic and environmental needs, once thats allows using precise amounts of active ingredients and only on aimed locations. Among the variety of matrix options used in this systems, poly (vinyl alcohol) has been larged employed and can be obtained by thermal cycles technics. Azadirachtin, an active ingredient found in Neem seed oil has been described as a repellent of different kinds of insects and has great agriculture\'s applicability. Based on compound properties, was proposed to develop a controlled release system to combat flea Ctenocephalides felis felis. In the present study was performed physicochemical characterizations of matrix and devices through gel fraction, swelling tests, differential scanning calorimetry, scanning electron microscopy and biological characterizations by cytotoxicity assay of Neen\'s oil, matrix and devices and analysis of flea\'s behavior at neem\'s oil presence by bioassay. The physical-chemical characterizations has enabled to choose the most suitable matrix to device\'s development. The biological characterizations has been demonstrated absence of oil\'s cytotoxicity, matrices and devices and bioassay has resulted in 40% mortality of fleas. On kinetic\'s release, was cheked that all used encapsulating agents has allowed the release neem\'s oil active principles.

Tendo em vista os vários problemas envolvendo a metodologia correntemente utilizada para a determinação da viabilidade no controle de qualidade da vacina BCG liofilizada, foi levado a efeito um estudo a respeito do assunto. Foi procedido um estudo de métodos alternativos a serem empregados em procedimentos de controle de qualidade da vacina BCG liofilizada. Com esse objetivo foi desenhado e construído um polarógrafo de eletrodo de oxigênio constituído de eletrodo de platina e o de referência de Ag-AgCl embutido em peça única e ainda dotado de sensor de temperatura, com circuito eletrônico permitindo a medida de consumo de oxigênio. Levou-se a efeito, então, estudo comparativo de viabilidade de vacina BCG liofilizada pela medida polarográfica de consumo de oxigênio em comparação à manométrica pelo clássico método de Warburg e o método de contagem de colônias (UFC). A análise de 66 diferentes lotes de vacina BCG liofilizada produzidas pelo Instituto Butantan, São Paulo, e pela Fundação Ataulpho de Paiva, Rio de Janeiro, demonstrou que a técnica polarográfica revelou ser altamente reprodutível e muito mais conveniente que os métodos manométrico e de contagem de colônias. Verificou-se que entre o método polarográfico e o manométrico e UFC os resultados da regressão linear mostraram correlação positiva de alta intensidade e significante ao nível de a= 0,05, permitindo indicar o método polarográfico descrito, como procedimento de escolha para operações de controle de qualidade em laboratórios de produção de vacina BCG bem como em Unidades de Saúde, para determinações adequadas de viabilidade de lotes de vacinas, a serem utilizadas para fins de imunização. / Considering the several problems regarding the procedures currently employed in the assays o f the control of quality, and the viability of the freeze-dried BCG vaccines, a study on various methods used for this purpose was carried out. Aiming to introduce a much more suitable, sensitive and less time consuming method than the classic Warburg technique and the colony count test (CFU) bacteriological procedure, currently used, a new oxygen electrode polarograph was designed with the aim of employing it for the study of the viability of the freeze-dried BCG vaccine. This polarograph electrode was built in a single piece containing the platinun and theAgAgCl reference electrode besides a temperature sensor. By using this assembly a comparative study was carried on the viability of the freeze-dried BCG vaccine assayed by the polarographic method in comparison with the manometric and the CFU methods. The analysis of the viability of 66 different batches of freeze-dried BCG vaccines produced at the Butantan Institute, São Paulo, and at the Ataulpho de Paiva Foundation, Rio de Janeiro, demonstrated that the polarograpbic technique revealed to be highly reliable and much more convenient than both the manometric and the CFU methods: it has been found out that between the polarographic and the manometric and the CFU, the linear regression sbowed a high intensity positive correlation and significant at the level of a = 0,05. In this way, the polarographic method could be considered as a choice method for the control of quality procedure as well as for the establishment of the viability of the batches of vaccines to be used for human immunization in Units of the Health Department.

MAX-phase ceramics are a class of ductile ceramic material group with the general molecular formula Mn+1AXn (n = 1, 2, 3….), where M is an early transition element, A is an element from the ‘A’ group of the periodic table and X is either nitride or carbide. One advantage of these materials is that they maintain their strength at high temperatures. In addition these ceramic materials possess the best properties of both ceramics and metals. Some of their important characteristics are low density, high stiffness, machinability, excellent thermal and electrical conductivity and they even exhibit some plasticity at elevated temperature. These amazing combinations of properties have made researchers foresee the technological importance of these materials as a structural ceramic for high temperature application. Since this ceramic is relatively new to the market, only a handful of work has been undertaken on this material and its applications are limited to heating elements. In addition, analysis of the thermodynamic data on this material is incomplete. This PhD work addresses this issue and conducts a complete thermodynamic analysis involved in the formation mechanism of the ternary titanium carbide MAX-phase Ti2AlC ceramic, using Self-propagating High temperature Synthesis (SHS) form of combustion synthesis process, based on the following exothermic reaction: (2+x) Ti + (y) Al + C → Ti2AlC + (x) Ti + (y) Al (i) Where x and y = 0.1. 0.2, 0.3… A thermodynamic model has been formulated to predict the temperature evolution during the reaction (i), for the formation of Ti2AlC using SHS process. In addition the effect of particle size in the elemental reaction has been studied on the formation mechanism of Ti2AlC and methods to control the porosity by fine tuning the particle size has been recognized. Manufacturing processes such as Self-propagating High temperature Synthesis (SHS), foam replication and freeze casting have been developed in this thesis to produce micro and macro porous Ti2AlC ceramic mainly for electrode applications. A systematic material development technique to produce macro porous Ti2AlC ceramic, using a foam replication technique has been established in this research work. The material fabricated by this technique has a uniform pore size (up to 5mm), with open interconnected pores and is ideal for a flow battery application which requires a multifunctional electrode material which is highly porous to allow the flow of electrolyte through it, is corrosion resistant and at the same time being electrically conductive. The mechanical properties of the ceramic produced by this method has been characterised and steps to mitigate the cracks and defects formed during the fabrication process to obtain structurally stable macro porous Ti2AlC ceramic has been reported in this work. This research demonstrates that one of the applications of macro porous Ti2AlC ceramic formed using foam replication technique is as an electrode material in a photo-Microbial Fuel Cell (p-MFC). Graded porosity micro porous Ti2AlC ceramics have also been fabricated using a freeze casting technique, with camphene as the freezing vehicle. A systematic material development process has been tailored for this particular material. A ceramic material with gradient pore size ranging from 27-305µm has been fabricated using this technique. This type of ceramic is a good candidate as an electrode material in micro-redox battery and for sensing applications. A variety of processing parameters such as solid loading (amount of ceramic content in the material), freezing temperature and mould material which affect the pore formation and pore size have been studied in this PhD and the range of porosities achieved by controlling these parameters have been reported.

Sistemas de liberação controlada vêm sendo cada vez mais utilizados em diferentes áreas tendo em vista sua aplicabilidade que os tornam uma tecnologia capaz de atender as necessidades econômicas e ambientais uma vez que permitem a utilização de princípios ativos em quantidades precisas e apenas nos locais desejados. Dentre a diversidade de opções de matrizes utilizadas nesses sistemas o poli(álcool vinílico) tem sido bastante empregado e pode ser obtido pela técnica de ciclos térmicos. Azadiractina, um princípio ativo encontrado em óleo de semente de Nim tem sido descrita como repelente de diferentes tipos de insetos e apresenta grande aplicabilidade na agricultura. Com base nas propriedades desse composto, propôs-se o desenvolvimento de um sistema de liberação controlada para combate a pulgas Ctenocephalides felis felis. No presente trabalho, foram realizadas caracterizações físico-químicas das matrizes e dispositivos através de ensaios de fração gel, intumescimento, calorimetria exploratória diferencial e microscopia eletrônica de varredura e caracterizações biológicas quanto à citotoxicidade do óleo de Nim, matrizes e dispositivos e bioensaio para análise do comportamento das pulgas na presença do óleo de Nim. As caracterizações físico-químicas permitiram a escolha da matriz mais adequada para o desenvolvimento do dispositivo. As caracterizações biológicas demonstraram ausência de citotoxicidade do óleo de Nim, das matrizes e dos dispositivos e o bioensaio resultou em 40% de mortalidade das pulgas testadas. Na cinética de liberação, verificou-se que todos os agentes encapsulantes utilizados permitiram a liberação de princípios ativos do óleo de Nim. / Controlled release systems has been increasingly used into different purposes due to its applicability that turns it onto a technology able to supply economic and environmental needs, once thats allows using precise amounts of active ingredients and only on aimed locations. Among the variety of matrix options used in this systems, poly (vinyl alcohol) has been larged employed and can be obtained by thermal cycles technics. Azadirachtin, an active ingredient found in Neem seed oil has been described as a repellent of different kinds of insects and has great agriculture\'s applicability. Based on compound properties, was proposed to develop a controlled release system to combat flea Ctenocephalides felis felis. In the present study was performed physicochemical characterizations of matrix and devices through gel fraction, swelling tests, differential scanning calorimetry, scanning electron microscopy and biological characterizations by cytotoxicity assay of Neen\'s oil, matrix and devices and analysis of flea\'s behavior at neem\'s oil presence by bioassay. The physical-chemical characterizations has enabled to choose the most suitable matrix to device\'s development. The biological characterizations has been demonstrated absence of oil\'s cytotoxicity, matrices and devices and bioassay has resulted in 40% mortality of fleas. On kinetic\'s release, was cheked that all used encapsulating agents has allowed the release neem\'s oil active principles.

O interesse pela extração dos compostos bioativos, a partir de fontes naturais, para o emprego na produção de alimentos funcionais tem aumentado, devido, principalmente, à crescente demanda por parte dos consumidores, por produtos mais saudáveis e que possam trazer benefícios à saúde. Dentre as fontes naturais de compostos bioativos, destaca-se o hibisco (Hibiscus sabdariffa L.), que é rico em antocianinas, flavonoides, ácidos fenólicos, carotenoides, dentre outros. Entretanto, quando os compostos bioativos são separados de suas matrizes, estes se tornam altamente instáveis frente a diversos fatores ambientais, necessitando serem protegidos. O recobrimento por microencapsulamento é uma alternativa para retardar a degradação desses compostos. Este estudo teve como objetivo a extração, identificação, quantificação e microencapsulamento por atomização e liofilização dos compostos bioativos dos cálices do hibisco. Primeiramente, foi realizada a extração exaustiva total dos carotenoides e compostos fenólicos por meio de solventes orgânicos, para a identificação e quantificação desses compostos. Também foi estudada a extração de antocianinas e demais compostos fenólicos por meio de solvente aquoso acidificado (ácido cítrico 2 %, p/v). A partir do melhor tratamento de extração, o extrato obtido foi microencapsulado mediante atomização e liofilização, empregando goma arábica (GA), goma guar parcialmente hidrolisada (GGPH) e polidextrose (PD) como agentes encapsulantes, na concentração de 10%. Os carotenoides e compostos fenólicos foram identificados e quantificados por HPLC-DAD-MS/MS (cromatografia líquida de alta eficiência com detecção por arranjo de diodos e espectrometria de massa). Vinte e um carotenoides foram encontrados, dos quais, quinze foram identificados. O total de carotenoides nos cálices de hibisco foi de 641,38 ± 23,61 μg/100 g massa fresca, sendo a all-trans-luteína e o all-trans--caroteno os compostos majoritários, representando 49 e 23%, respectivamente. Para os compostos fenólicos, foram encontrados vinte compostos, dos quais, catorze foram identificados. As antocianinas foram os compostos majoritários nos cálices de hibisco, sendo que a delfinidina 3-sambubiosídeo e cianidina 3-sambubiosídeo representaram 41 e 13% do total de compostos fenólicos, respectivamente. Dentre os ácidos fenólicos, os componentes majoritários foram o ácido 3-cafeoilquínico e ácido 5-cafeoilquínico, representando 15 e 13% do total de compostos fenólicos, respectivamente. Para a extração aquosa acidificada, foi utilizado um planejamento experimental fatorial fracionado (24-1), com quatro fatores: concentração de enzima, temperatura, velocidade de agitação e tempo de extração. A partir da ANOVA, os efeitos principais e de interação foram avaliados, tendo como respostas Chroma, antocianinas monoméricas totais (TMA), capacidade redutora, ABTS e compostos fenólicos. A partir dos resultados, o melhor tratamento foi: 55 °C, 50 μL de enzima/1000 g extrato, 400 rpm e 4 horas de extração, obtendo-se nessa condição de extração 3,82 mg/g extrato em base seca para TMA e 17,59 mg/g de extrato em base seca para compostos fenólicos totais, que resultou em capacidade antioxidante de 7,72 μmol Eq. Trolox/g de extrato em base seca, avaliado por ABTS e de 3,96 mg GAE/g de de extrato em base seca, avaliado pela capacidade redutora. Este extrato foi empregado no estudo de encapsulamento, por atomização (140 ºC) e liofilização (-68 ºC por 24 horas), utilizando GA, GGPH e PD como encapsulantes. Observou-se que o melhor tratamento foi por liofilização empregando GA como encapsulante, resultando em 2,83 mg/g amostra em base seca para TMA, capacidade antioxidante de 2,98 mg GAE/g amostra em base seca e 5.67 μmol Eq. Trolox/g amostra em base seca, avaliados por capacidade redutora e ABTS, respectivamente. Entretanto, quando foram avaliadas as propriedades físicas e morfológicas dos pós, as amostras elaboradas por atomização e usando GA e GGPH apresentaram os melhores desempenhos, onde os valores de solubilidade, higroscopicidade e umidade foram de 95,8 e 95,2%, 31,3 e 28,9%, 1,9 e 2,4%, respectivamente. Para a temperatura de transição vítrea (Tg), os tratamentos que utilizaram GA e GGPH nos dois métodos de encapsulamento, tiveram os maiores valores de Tg, variando de 10,9 a 17,4 ºC. Já para os tratamentos que utilizaram a PD como material de parede, os valores foram de (0,7 °C), tanto na atomização como na liofilização. Na microscopia também foi observado um melhor desempenho nas micropartículas atomizadas usando GA e GGPH, as quais mostraram partículas mais esféricas e sem tendência de atração e aderência entre si. Em relação ao diâmetro médio de partícula (D[4, 3]), os tratamentos liofilizados tiveram partículas maiores que os atomizados, variando de 101,7 a 143,1 μm para os liofilizados, e de 5,4 a 7,3 μm para os atomizados. Quanto ao span, o qual avalia distribuição de tamanho de partícula, variou de 1,90 a 2,00 para as amostras atomizadas e de 3,06 a 3,19 para as amostras liofilizadas, indicando que houve uma boa uniformidade na distribuição de tamanho de partícula. Conclui-se que o hibisco é uma matriz com ampla composição de compostos bioativos e tem potencial para aplicação em alimentos. / The interest in the extraction of bioactive compounds from natural sources, for use in the production of functional foods has increased, mainly due to the growing demand by consumers for healthier products and can bring health benefits. Among the natural sources of bioactive compounds, stands out the hibiscus (Hibiscus sabdariffa L.), which is rich in anthocyanins, flavonoids, phenolic acids, carotenoids, among others. However, when the bioactive compounds are separated from their matrix, they become highly unstable against various environmental factors and need to be protected. The coating by microencapsulation is an alternative to slow the degradation of these compounds. This study aimed at the extraction, identification, quantification and microencapsulation by spray drying and freeze drying of bioactive compounds of hibiscus calyces. Firstly, a thorough exhaustive extraction of carotenoids and phenolic compounds by organic solvents was performed for identification and quantification of these compounds. The extraction of anthocyanins was also studied along with other phenolic compounds by an aqueous solvent acidified (2% citric acid, w/v). From the best treatment for extraction, the extract obtained was microencapsulated by spray drying and freeze drying using Arabic gum (GA), partially hydrolyzed guar gum (PHGG) and polydextrose (PD) as encapsulating agents in a concentration of 10%. Carotenoids and phenolic compounds were identified and quantified by HPLC-DAD-MS/MS (high-performance liquid chromatography with diode array detection and mass spectrometry). Twenty-one carotenoids were found, of which fifteen were identified. The total carotenoids in hibiscus calyces was 641.38 ± 23.61 mg/100 g fresh weight, with the all-trans-lutein and all-trans-β-carotene the major compounds, representing 49 and 23%, respectively. Regarding the phenolic compounds it was found twenty of those, of which fourteen have been identified. Anthocyanins were the main components in the hibiscus calyces, and delphinidin and cyanidin 3-sambubioside 3-sambubioside represented 41 and 13% of total phenolic compounds, respectively. Among the phenolic acids, the major components were the 3-caffeoylquinic acid and 5-caffeoylquinic acid, representing 15 and 13% of total phenolic compounds, respectively. For acidified aqueous extraction, we used a fractional factorial design (24-1) with four factors: enzyme concentration, temperature, stirring speed and extraction time. From the ANOVA, the main and interaction effects were assessed as answers: Chroma, total anthocyanins monomeric (TMA), reducing capacity, ABTS and phenolic compounds. From the results, the best treatment was with 55 °C, 50 μL of enzyme/1000 g extract, 400 rpm and 4 hours of extraction, it was obtained in this extraction condition 3.82 mg/g extract on a dry basis for TMA and 17.59 mg/g extract on a dry basis for phenolic compounds, which resulted in antioxidant capacity of 7.72 μmol Eq. Trolox/g extract on a dry basis, evaluated by ABTS and 3.96 mg GAE/g extract on a dry basis, assessed by reducing capacity. This extract was used for the encapsulation study, by spray drying (140 °C) and freeze drying (-68 ° C for 24 hours) using GA, PHGG, and PD as encapsulants. It was observed that the best treatment is by freeze drying using GA as encapsulant, resulting in 2.83 mg/g sample on dry basis for TMA, antioxidant capacity of 2.98 mg GAE/g sample on dry basis and 5.67 μmol Eq. Trolox/g sample on dry basis, evaluated by reducing capacity and ABTS, respectively. However, when we evaluated the physical and morphological properties of powders, samples prepared by spray drying and using GA and PHGG showed the best performance, and the values for solubility, hygroscopicity and moisture were 95.8 and 95.2%, 31.3 and 28.9%, 1.9 and 2.4%, respectively. For the glass transition temperature (Tg), treatments with GA and PHGG on both encapsulation methods had high Tg values ranging from 10.9 to 17.4 °C. As for treatments of PD as wall material, the values were (0.7 °C), both the spray drying as in freeze drying. In microscopy was also observed improved performance in spray-dried microparticles using GA and PHGG, which showed more spherical particles and with no tendency to attract and adhere to each other. Regarding the average particle diameter (D [4, 3]), the freeze-dried treatments had higher spray-dried particles ranging from 101.7 to 143.1 μm for freeze-dried, and 5.4 to 7.3 μm for spray-dried. As the span, which assesses particle size distribution ranged from 1.90 to 2.00 for spray-dried samples and 3.06 to 3.19 for the freeze-dried samples, indicating that there was a good uniformity in the size in the distribution of the size of the particle. It follows that hibiscus is a matrix with broad composition and bioactive compounds have potential for application in foods.

Tendo em vista os vários problemas envolvendo a metodologia correntemente utilizada para a determinação da viabilidade no controle de qualidade da vacina BCG liofilizada, foi levado a efeito um estudo a respeito do assunto. Foi procedido um estudo de métodos alternativos a serem empregados em procedimentos de controle de qualidade da vacina BCG liofilizada. Com esse objetivo foi desenhado e construído um polarógrafo de eletrodo de oxigênio constituído de eletrodo de platina e o de referência de Ag-AgCl embutido em peça única e ainda dotado de sensor de temperatura, com circuito eletrônico permitindo a medida de consumo de oxigênio. Levou-se a efeito, então, estudo comparativo de viabilidade de vacina BCG liofilizada pela medida polarográfica de consumo de oxigênio em comparação à manométrica pelo clássico método de Warburg e o método de contagem de colônias (UFC). A análise de 66 diferentes lotes de vacina BCG liofilizada produzidas pelo Instituto Butantan, São Paulo, e pela Fundação Ataulpho de Paiva, Rio de Janeiro, demonstrou que a técnica polarográfica revelou ser altamente reprodutível e muito mais conveniente que os métodos manométrico e de contagem de colônias. Verificou-se que entre o método polarográfico e o manométrico e UFC os resultados da regressão linear mostraram correlação positiva de alta intensidade e significante ao nível de a= 0,05, permitindo indicar o método polarográfico descrito, como procedimento de escolha para operações de controle de qualidade em laboratórios de produção de vacina BCG bem como em Unidades de Saúde, para determinações adequadas de viabilidade de lotes de vacinas, a serem utilizadas para fins de imunização. / Considering the several problems regarding the procedures currently employed in the assays o f the control of quality, and the viability of the freeze-dried BCG vaccines, a study on various methods used for this purpose was carried out. Aiming to introduce a much more suitable, sensitive and less time consuming method than the classic Warburg technique and the colony count test (CFU) bacteriological procedure, currently used, a new oxygen electrode polarograph was designed with the aim of employing it for the study of the viability of the freeze-dried BCG vaccine. This polarograph electrode was built in a single piece containing the platinun and theAgAgCl reference electrode besides a temperature sensor. By using this assembly a comparative study was carried on the viability of the freeze-dried BCG vaccine assayed by the polarographic method in comparison with the manometric and the CFU methods. The analysis of the viability of 66 different batches of freeze-dried BCG vaccines produced at the Butantan Institute, São Paulo, and at the Ataulpho de Paiva Foundation, Rio de Janeiro, demonstrated that the polarograpbic technique revealed to be highly reliable and much more convenient than both the manometric and the CFU methods: it has been found out that between the polarographic and the manometric and the CFU, the linear regression sbowed a high intensity positive correlation and significant at the level of a = 0,05. In this way, the polarographic method could be considered as a choice method for the control of quality procedure as well as for the establishment of the viability of the batches of vaccines to be used for human immunization in Units of the Health Department.

In an effort to develop more efficient and practical interventions for athletic performance, some behavioral researchers have incorporated a variety of technological innovations. In sports research, only a few studies have examined the effects of video feedback on athletic skill development. The effects of combining expert video modeling with self video feedback as an adjunct to standard coaching techniques were analyzed in this study. Participants in this study were four 7-10 year old competitive gymnasts. During the intervention, each gymnast performed a specific gymnastics skill and then viewed a pre-recorded video segment showing an expert gymnast performing the same skill. The gymnast then viewed a video replay of her own performance of the skill. Next she saw a side by side slow motion with freeze frame comparison of her performance with that of the expert model. Lastly, in normal time, the gymnast viewed the expert video clip again, followed by her own performance of the skill. The effect of expert video modeling with self video feedback on gymnastics skill performance was evaluated in a multiple baseline across behaviors research design. The results showed that the gymnasts' skills increased in performance following exposure to video feedback.

<p>Research on freeze-thaw resistance of concrete in general and on curing and moisture conditions in particular is motivated from an economic and product sustainability point of view. Specifically, it is argued for the importance of considering the effect of curing and test exposure conditions on the moisture uptake and performance during freeze-thaw. Due to the demonstrated importance of moisture conditions on performance, they should be related to those of field service conditions when choosing a test procedure in a particular case. This is vital for adequate testing of new</p><p>and more sustainable concrete materials.</p>

Research on freeze-thaw resistance of concrete in general and on curing and moisture conditions in particular is motivated from an economic and product sustainability point of view. Specifically, it is argued for the importance of considering the effect of curing and test exposure conditions on the moisture uptake and performance during freeze-thaw. Due to the demonstrated importance of moisture conditions on performance, they should be related to those of field service conditions when choosing a test procedure in a particular case. This is vital for adequate testing of new and more sustainable concrete materials.

A gel is a cross-linked polymer network that spans an entire liquid medium; its properties depend strongly on the interaction of the polymer and the liquid medium. There are various ways to induce gelation in different systems such as altering temperature or pH. In this study, phenol extracted protein fractions from non-acclimated (NA) and cold-acclimated (CA) winter rye (Secale cereale L. cv Musketeer) leaf tissue were subjected to freeze-thaw treatment. Gelation was induced in the NA and CA extracts after repeated freeze-thaw treatments, accompanied by a change in sample rheological properties. Further experimentation revealed that gel formation only occurred at high pH (pH 12.0) and that a minimum of 3 to 4 freeze-thaw cycles were required. The viscosity of the protein gel increased 5.7- to 9.5-fold in the NA and CA extracts respectively upon freeze-thaw. Experiments optimizing the extraction conditions and protein concentration were also performed. The gel was stable and only a specific combination of chaotropic agent, anionic surfactant and reducing agent such as urea, sodium docecyl sulfate (SDS) and â-mercaptoethanol (â-ME) with heating could disrupt the gel network. The gel was composed of several proteins in the extracts as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Based on SDS-PAGE analysis, ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) was identified as the major protein component in the gel. Various experiments were performed to assess the role of Rubisco in gel formation; however, the results were inconclusive. It is suggested that these extracts may contain antifreeze proteins (AFPs) that have been demonstrated to form amyloid gels upon freeze-thaw. Further studies examining the composition and mechanism of gel formation may result in a future role for this material in the food industry.