No description available.

The electromagnetic shielding effectiveness of kenaf bast fiber based composites with different iron oxide impregnation levels was investigated. The kenaf fibers were retted to remove the lignin and extractives from the pores in fibers, and then magnetized. Using the unsaturated polyester and the magnetized fibers, kenaf fiber based composites were manufactured by compression molding process. The transmission energies of the composites were characterized when the composite samples were exposed under the irradiation of electromagnetic (EM) wave with a changing frequency from 9 GHz to 11 GHz. Using the scanning electron microscope (SEM), the iron oxide nanoparticles were observed on the surfaces and inside the micropore structures of single fibers. The SEM images revealed that the composite’s EM shielding effectiveness was increased due to the adhesion of the iron oxide crystals to the kenaf fiber surfaces. As the Fe content increased from 0% to 6.8%, 15.9% and 18.0%, the total surface free energy of kenaf fibers with magnetizing treat increased from 44.77 mJ/m2 to 46.07 mJ/m2, 48.78 mJ/m2 and 53.02 mJ/m2, respectively, while the modulus of elasticity (MOE) reduced from 2,875 MPa to 2,729 MPa, 2,487 MPa and 2,007 MPa, respectively. Meanwhile, the shielding effectiveness was increased from 30-50% to 60-70%, 65-75% and 70-80%, respectively.

Development of nanostructures as MR contrast agent will significantly improve the field of disease diagnostics. Contrast agents such as iron oxide nanoparticles are less toxic compared to more commonly used gadolinium based agents. A subclass of iron based nano particles are super paramagnetic iron oxide nano particles, (SPIOs) which are widely studied MR contrast agents useful in both imaging and drug delivery applications. In this work, SPIOs were synthesized and characterized and used for cellular tracking and multi modal labeling. A new solvent exchange method was utilized to coat different core size iron oxide nano particles. SPIOs were characterized for in-vivo imaging using MR and they had a very uniform size distribution which was determine using dynamic light scattering (DLS) and transmission electron microscopy. Furthermore, blood circulation half-life of 16nm SPIOs were determined through tail vein injection. SPIOs have many applications among which is the in vivo tracking of stem cells which is critical for determination of stem cells fate after injection. Magnetic Resonance (MR) as a non-invasive method can provide significant information about the fate of the cells as well as determination of the success rate of therapeutic cellular deliveries. Mesenchymal stem cells can be loaded with super paramagnetic iron oxide nano particles (SPIOs) and have their movements followed once planted in vivo. We present our findings on the effect of SPIO concentration and stem cell density on the MR signal and transverse relaxation time. Our preliminary results indicated that SPIOs do not cause mesenchymal stem cell cytotoxicity and do not affect proliferation ability up to 200 μg/ml concentration. The release of the nanoparticles was investigated 24 hours post internalization and the result showed that SPIOs will stay inside the cell. We also found that the contrast increases in a concentration dependent manner. Our results suggest that using MR with low concentration of SPIOs is a novel and promising method for tracking of mesenchymal stem cells. In this work SPIOs were also labeled with 64Cu to investigate their potential for multi modal positron emission tomography (PET) MR imaging. Dual modality PET MR SPIO contrast agent can be synthesized to image diseases such as cancer and atherosclerosis. The advantage is the non-invasive and early detection of disease at molecular lever before it has spread to late stages or in case of the atherosclerosis before the plaque has blocked the vessel. To develop a multi modal contrast agent, a positron emitter, 64Cu (half-life of 12.701 ± 0.002 hours), was used in labeling and synthesis was performed all in one step with the addition of 64Cu chelator, 14-PE DTPA followed by radiolabeling for both 6.5nm SPIO and 17nm SPIO. After labeling and purification with the desalting column, the amount of dissociated 64Cu in the solution was determined using radio thin layer chromotagraphy (TLC) and the particle was shown to have minimum amount of fee 64Cu. Serum stability of labeled SPIO was determined in vitro by incubating 64Cu-labeled SPIOs in mouse serum at 37 °C for 24 hr with constant shaking. Radio TLC result then revealed that 64Cu stays bounded to the SPIO after 24 hours in mouse serum. This means that 64Cu labeled SPIO has a great potential as a dual modality contrast agents and further in-vivo studies are required to verify the findings.

Foi realizado um experimento com a finalidade de apresentar um protocolo preciso, simples, rápido e de baixo custo para determinar os coeficientes de metabolizabilidade dos nutrientes e o valor energético das dietas. Para tal, determinaram-se os CMMS, CMPB e CMEB e EMAn através da comparação de diferentes metodologias de digestibilidade in vivo que incluem a utilização ou não de indicador Cr2O3 a 0,5% (coleta parcial) ou marcador Fe2O3 a 1% e a aplicação ou não de jejum (0, 4, 6 e 8 horas) pré-inicio de coleta e pós-período de alimentação. Também a duração do período de coleta foi testada (3 ou 5 dias). Foi estudado o efeito dos períodos de jejum sobre o tamanho dos órgãos digestivos. Foram utilizados 81 frangos de corte, machos, com 21 dias de idade, distribuídos individualmente em gaiolas de metabolismo, constituindo 9 tratamentos (TRAT) com 9 repetições em delineamento completamente casualizado. Em todos os TRAT houve 4 dias de adaptação à uma dieta única, com 3055 kcal EM/kg, à base de milho e farelo de soja. A água foi fornecida à vontade. Após o período de coleta, 5 aves por TRAT, que receberam jejum, foram pesadas e abatidas e o papo, moela+proventrículo, intestino delgado e cólon+ceco foram pesados, bem como o conteúdo presente em cada um. Através do aparecimento do marcador foi determinada a duração da passagem de digesta pelo TGI das aves. O tempo de passagem foi considerado como o tempo entre o fornecimento da dieta com óxido férrico e o início do aparecimento das excretas marcadas. Os coeficientes de metabolismo e a energia não diferiram significativamente na coleta total comparandose 3 ou 5 dias de coleta (P>0,05). O uso do marcador Fe2O3 e três dias de coleta, resultou em menor valor do CMPB (P<0,02) em relação à coleta total sem marcador. Na metodologia de coleta parcial com 5 dias de coleta, observou-se coeficientes de menor valor para todas as respostas (P<0,05), comparados a 3 dias de coleta. O uso da metodologia de coleta total resultou em maiores CMMS e CMPB (P<0,05) comparado à coleta parcial, em função de uma taxa incompleta de recuperação do Cr2O3 na excreta. Não foi observada influencia do jejum sobre o tamanho dos órgãos, indicando que em até 8 horas de jejum não há mudança no tamanho absoluto ou relativo dos mesmos. No entanto, o peso relativo do jejuno das aves submetidas a 4, 6 e 8 horas de jejum foi maior (P<0,03) do que o das aves sem jejum. O tempo médio de passagem da ração foi estimado em 228 minutos. Conclui-se que a coleta total de excretas, por um período de 3 dias, sem o uso de jejum, resulta no melhor método de avaliação de ingredientes e ração. / One experiment was conducted in order to define a reliable, easy to apply and non expensive protocol to determinate nutrient and energy metabolizability values of broiler chicken diets. For this purpose, metabolizability coefficients (MC) of dry matter (DM); crude protein (CP); gross energy (GE) and nitrogen-corrected apparent metabolizable energy (AMEn) were calculated through the comparison of different in vivo digestibility methodologies including the utilization of Cr2O3 (0,5%) as an indicator (partial collection) or Fe2O3 (1%) as a marker; fasting, prior to excreta collection and at the end of the feeding period (0, 4, 6 and 8 hours). Also, two excreta collection periods were tested (3 and 5 days). It was assessed the effect of fasting on digestive organs weight. Eighty one 21 days male broilers were distributed individually in metabolic cages used distributed in nine treatments (T) and nine replicates per T, in a completely randomized design. Birds were held in individual metabolism cages located in a controlledtemperature room. All T had a 4 day adaptation period to a single diet of 3055 kcal ME/kg, based on corn and soybean meal. Water was offered ad libitum. At the end of fasting, 5 birds per T that received fasting were sacrificed by cervical dislocation and weighed. Crop, proventriculus+gizzard, small intestine and the ceca+colon were removed and weighed individually as their contents as well. The passage time along broiler GIT was measured with ferric oxide as a marker. The passage time was taken as the time elapsed from time of marker administration to time of the first observation of droppings red color. Metabolism coefficients and energy were not significantly different between 3 and 5 days of total collection (P>0,05). CPMC was lower (P<0,02) for Fe2O3 utilization and 3 days excreta collection compared to the total collection. With the methodology of partial collection with 5 days of collection, it was observed the lowest values for all the responses (P<0,05), compared to 3 days collection period. The use of the total collection methodology produced the highest DMMC and CPMC (P<0,05) compared to partial collection, due to the incomplete recovery of the Cr2O3 from the excreta. No fasting influence was observed on the digestive organ sizes, indicating that until 8 hours of fasting no changes are observed in either relative or absolute organs weight. However, the relative jejunum weight of birds submitted to 4, 6 and 8 hours was higher (P<0,03) than those of birds under no fasting. The mean passage time of fed through broiler GIT was 228 minutes. It was conclude that total collection, during a 3 days period, without fasting utilization, is the best methodology for poultry ingredient and fed evaluation.

Foi realizado um experimento com a finalidade de apresentar um protocolo preciso, simples, rápido e de baixo custo para determinar os coeficientes de metabolizabilidade dos nutrientes e o valor energético das dietas. Para tal, determinaram-se os CMMS, CMPB e CMEB e EMAn através da comparação de diferentes metodologias de digestibilidade in vivo que incluem a utilização ou não de indicador Cr2O3 a 0,5% (coleta parcial) ou marcador Fe2O3 a 1% e a aplicação ou não de jejum (0, 4, 6 e 8 horas) pré-inicio de coleta e pós-período de alimentação. Também a duração do período de coleta foi testada (3 ou 5 dias). Foi estudado o efeito dos períodos de jejum sobre o tamanho dos órgãos digestivos. Foram utilizados 81 frangos de corte, machos, com 21 dias de idade, distribuídos individualmente em gaiolas de metabolismo, constituindo 9 tratamentos (TRAT) com 9 repetições em delineamento completamente casualizado. Em todos os TRAT houve 4 dias de adaptação à uma dieta única, com 3055 kcal EM/kg, à base de milho e farelo de soja. A água foi fornecida à vontade. Após o período de coleta, 5 aves por TRAT, que receberam jejum, foram pesadas e abatidas e o papo, moela+proventrículo, intestino delgado e cólon+ceco foram pesados, bem como o conteúdo presente em cada um. Através do aparecimento do marcador foi determinada a duração da passagem de digesta pelo TGI das aves. O tempo de passagem foi considerado como o tempo entre o fornecimento da dieta com óxido férrico e o início do aparecimento das excretas marcadas. Os coeficientes de metabolismo e a energia não diferiram significativamente na coleta total comparandose 3 ou 5 dias de coleta (P>0,05). O uso do marcador Fe2O3 e três dias de coleta, resultou em menor valor do CMPB (P<0,02) em relação à coleta total sem marcador. Na metodologia de coleta parcial com 5 dias de coleta, observou-se coeficientes de menor valor para todas as respostas (P<0,05), comparados a 3 dias de coleta. O uso da metodologia de coleta total resultou em maiores CMMS e CMPB (P<0,05) comparado à coleta parcial, em função de uma taxa incompleta de recuperação do Cr2O3 na excreta. Não foi observada influencia do jejum sobre o tamanho dos órgãos, indicando que em até 8 horas de jejum não há mudança no tamanho absoluto ou relativo dos mesmos. No entanto, o peso relativo do jejuno das aves submetidas a 4, 6 e 8 horas de jejum foi maior (P<0,03) do que o das aves sem jejum. O tempo médio de passagem da ração foi estimado em 228 minutos. Conclui-se que a coleta total de excretas, por um período de 3 dias, sem o uso de jejum, resulta no melhor método de avaliação de ingredientes e ração. / One experiment was conducted in order to define a reliable, easy to apply and non expensive protocol to determinate nutrient and energy metabolizability values of broiler chicken diets. For this purpose, metabolizability coefficients (MC) of dry matter (DM); crude protein (CP); gross energy (GE) and nitrogen-corrected apparent metabolizable energy (AMEn) were calculated through the comparison of different in vivo digestibility methodologies including the utilization of Cr2O3 (0,5%) as an indicator (partial collection) or Fe2O3 (1%) as a marker; fasting, prior to excreta collection and at the end of the feeding period (0, 4, 6 and 8 hours). Also, two excreta collection periods were tested (3 and 5 days). It was assessed the effect of fasting on digestive organs weight. Eighty one 21 days male broilers were distributed individually in metabolic cages used distributed in nine treatments (T) and nine replicates per T, in a completely randomized design. Birds were held in individual metabolism cages located in a controlledtemperature room. All T had a 4 day adaptation period to a single diet of 3055 kcal ME/kg, based on corn and soybean meal. Water was offered ad libitum. At the end of fasting, 5 birds per T that received fasting were sacrificed by cervical dislocation and weighed. Crop, proventriculus+gizzard, small intestine and the ceca+colon were removed and weighed individually as their contents as well. The passage time along broiler GIT was measured with ferric oxide as a marker. The passage time was taken as the time elapsed from time of marker administration to time of the first observation of droppings red color. Metabolism coefficients and energy were not significantly different between 3 and 5 days of total collection (P>0,05). CPMC was lower (P<0,02) for Fe2O3 utilization and 3 days excreta collection compared to the total collection. With the methodology of partial collection with 5 days of collection, it was observed the lowest values for all the responses (P<0,05), compared to 3 days collection period. The use of the total collection methodology produced the highest DMMC and CPMC (P<0,05) compared to partial collection, due to the incomplete recovery of the Cr2O3 from the excreta. No fasting influence was observed on the digestive organ sizes, indicating that until 8 hours of fasting no changes are observed in either relative or absolute organs weight. However, the relative jejunum weight of birds submitted to 4, 6 and 8 hours was higher (P<0,03) than those of birds under no fasting. The mean passage time of fed through broiler GIT was 228 minutes. It was conclude that total collection, during a 3 days period, without fasting utilization, is the best methodology for poultry ingredient and fed evaluation.

Foi realizado um experimento com a finalidade de apresentar um protocolo preciso, simples, rápido e de baixo custo para determinar os coeficientes de metabolizabilidade dos nutrientes e o valor energético das dietas. Para tal, determinaram-se os CMMS, CMPB e CMEB e EMAn através da comparação de diferentes metodologias de digestibilidade in vivo que incluem a utilização ou não de indicador Cr2O3 a 0,5% (coleta parcial) ou marcador Fe2O3 a 1% e a aplicação ou não de jejum (0, 4, 6 e 8 horas) pré-inicio de coleta e pós-período de alimentação. Também a duração do período de coleta foi testada (3 ou 5 dias). Foi estudado o efeito dos períodos de jejum sobre o tamanho dos órgãos digestivos. Foram utilizados 81 frangos de corte, machos, com 21 dias de idade, distribuídos individualmente em gaiolas de metabolismo, constituindo 9 tratamentos (TRAT) com 9 repetições em delineamento completamente casualizado. Em todos os TRAT houve 4 dias de adaptação à uma dieta única, com 3055 kcal EM/kg, à base de milho e farelo de soja. A água foi fornecida à vontade. Após o período de coleta, 5 aves por TRAT, que receberam jejum, foram pesadas e abatidas e o papo, moela+proventrículo, intestino delgado e cólon+ceco foram pesados, bem como o conteúdo presente em cada um. Através do aparecimento do marcador foi determinada a duração da passagem de digesta pelo TGI das aves. O tempo de passagem foi considerado como o tempo entre o fornecimento da dieta com óxido férrico e o início do aparecimento das excretas marcadas. Os coeficientes de metabolismo e a energia não diferiram significativamente na coleta total comparandose 3 ou 5 dias de coleta (P>0,05). O uso do marcador Fe2O3 e três dias de coleta, resultou em menor valor do CMPB (P<0,02) em relação à coleta total sem marcador. Na metodologia de coleta parcial com 5 dias de coleta, observou-se coeficientes de menor valor para todas as respostas (P<0,05), comparados a 3 dias de coleta. O uso da metodologia de coleta total resultou em maiores CMMS e CMPB (P<0,05) comparado à coleta parcial, em função de uma taxa incompleta de recuperação do Cr2O3 na excreta. Não foi observada influencia do jejum sobre o tamanho dos órgãos, indicando que em até 8 horas de jejum não há mudança no tamanho absoluto ou relativo dos mesmos. No entanto, o peso relativo do jejuno das aves submetidas a 4, 6 e 8 horas de jejum foi maior (P<0,03) do que o das aves sem jejum. O tempo médio de passagem da ração foi estimado em 228 minutos. Conclui-se que a coleta total de excretas, por um período de 3 dias, sem o uso de jejum, resulta no melhor método de avaliação de ingredientes e ração. / One experiment was conducted in order to define a reliable, easy to apply and non expensive protocol to determinate nutrient and energy metabolizability values of broiler chicken diets. For this purpose, metabolizability coefficients (MC) of dry matter (DM); crude protein (CP); gross energy (GE) and nitrogen-corrected apparent metabolizable energy (AMEn) were calculated through the comparison of different in vivo digestibility methodologies including the utilization of Cr2O3 (0,5%) as an indicator (partial collection) or Fe2O3 (1%) as a marker; fasting, prior to excreta collection and at the end of the feeding period (0, 4, 6 and 8 hours). Also, two excreta collection periods were tested (3 and 5 days). It was assessed the effect of fasting on digestive organs weight. Eighty one 21 days male broilers were distributed individually in metabolic cages used distributed in nine treatments (T) and nine replicates per T, in a completely randomized design. Birds were held in individual metabolism cages located in a controlledtemperature room. All T had a 4 day adaptation period to a single diet of 3055 kcal ME/kg, based on corn and soybean meal. Water was offered ad libitum. At the end of fasting, 5 birds per T that received fasting were sacrificed by cervical dislocation and weighed. Crop, proventriculus+gizzard, small intestine and the ceca+colon were removed and weighed individually as their contents as well. The passage time along broiler GIT was measured with ferric oxide as a marker. The passage time was taken as the time elapsed from time of marker administration to time of the first observation of droppings red color. Metabolism coefficients and energy were not significantly different between 3 and 5 days of total collection (P>0,05). CPMC was lower (P<0,02) for Fe2O3 utilization and 3 days excreta collection compared to the total collection. With the methodology of partial collection with 5 days of collection, it was observed the lowest values for all the responses (P<0,05), compared to 3 days collection period. The use of the total collection methodology produced the highest DMMC and CPMC (P<0,05) compared to partial collection, due to the incomplete recovery of the Cr2O3 from the excreta. No fasting influence was observed on the digestive organ sizes, indicating that until 8 hours of fasting no changes are observed in either relative or absolute organs weight. However, the relative jejunum weight of birds submitted to 4, 6 and 8 hours was higher (P<0,03) than those of birds under no fasting. The mean passage time of fed through broiler GIT was 228 minutes. It was conclude that total collection, during a 3 days period, without fasting utilization, is the best methodology for poultry ingredient and fed evaluation.

High-Gradient Magnetic Separation (HGMS) is a powerful separation process that has great potential for industrial wastewater treatment, particularly for the removal and recovery of paramagnetic colloidal particles. The chief advantages of HGMS are that the separation is reversible and potentially selective. However, these advantages are compromised if non-magnetic filtration mechanisms influence significantly the capture of particles. The objective of this study was to identify the chief mechanisms responsible for the removal of ferric oxide (Fe2O3) from water by an HGMS process. This objective was achieved by measuring the effects of applied magnetic induction, collector radius, and fluid velocity on the removal efficiency (RE) of a stainless-steel filter column. These factors were tested on the removal of bare Fe2O3 particles and particles treated with a surfactant (sodium dodecyl sulfate, SDS). The results were compared to the predictions of a trajectory model which simulates particle capture by a magnetic force. The experimental results show that non-magnetic force mechanisms are primarily responsible for the removal of bare Fe2O3 particles for the experimental conditions used in this work. For these particles, the three factors tested had no significant effect on the RE, and 90.1% of the particles were removed without a magnetic force. These results differed sharply from modeling predictions. However, the magnetic force mechanism is primarily responsible for the removal of surfactant-treated Fe2O3 particles. The three factors investigated had a marked effect on the RE, and only 10.8% of the particles were removed without a magnetic force. An increase in magnetic induction from 0.2 to 0.5 T increased the RE from 79.9 to 93.4 %; a decrease in wire radius from 49 to 15 Ym increased the RE from 60.2 to 93.4%, and a decrease in fluid velocity from 0.5 to 0.1 cm/s increased the RE from 69.5 to 95.3%. These results agreed closely with the model predictions.This study demonstrates that by reducing the effect of attractive non-magnetic forces on filtration, surfactant treatment of colloidal particles can potentially preserve and enhance these two key advantages, i.e., regeneration and selectivity of HGMS processes.

This work details the synthesis and growth mechanisms of 1D magnetic and semiconducting nanostructures. Specifically, magnetic iron oxide and ZnS-SiO2 nanowires are examined. These materials are chosen due to their promise for biomedical and electronic applications and the perceived need to both create these structures as tools for these applications and to understand their formation processes so that they can be manufactured at a scale and efficiency suitable for commercialization. The current state and impact of nanotechnology is discussed through the lens of continuing technological advances and environmental factors, and the term is defined according to a specific set of criterion involving size, utility, and uniqueness. Details of synthesis and characterization of Fe3O4, ε-Fe2O3, and ZnS-SiO2 core-shell nanowires are presented. Observations regarding the growth of these structures are paired with additional experiments, simple simulations, and other literature to discuss the classical VLS growth process in general, and its applicability to these structures in particular. Finally, some exciting future applications are discussed, with details for initial experimental work presented in the appendix.

No description available.

Fluoride in drinking water can lead to a crippling disease called fluorosis. As there is no cure for fluorosis, prevention is the only means of controlling the disease and research into fluoride remediation is critical. This work begins by providing a new approach to assessing fluoride remediation strategies using a combination of groundwater chemistry, saturation indices, and multivariate statistics based on the results of a large groundwater survey performed in a fluoride-contaminated region of India. From the Indian groundwater study, it was noted that one technique recommended for defluoridation involved using hydrous ferric oxide (HFO) as a solid phase sorbent for fluoride. This prompted investigation of bacteriogenic iron oxides (BIOS), a biogenic form of HFO, as a means of approaching bioremediation of fluoride. Batch sorption experiments at ionic strengths ranging from 0.001 to 0.1 M KNO3 and time course kinetic studies with BIOS and synthetic HFO were conducted to ascertain total sorption capacities (ST), sorption constants (Ks), and orders of reaction (n), as well as forward (kf) and reverse (kr) rate constants. Microcosm titration experiments were also conducted with BIOS and HFO in natural spring water from a groundwater discharge zone to evaluate fluoride sorption under field conditions. This thesis contributes significant, new information regarding the interaction between fluoride and BIOS, advancing knowledge of fluoride remediation and covering new ground in the uncharted field of fluoride bioremediation.