Os aços com adição de boro temperados e revenidos têm sido utilizados em diversas aplicações que exigem um compromisso entre boas propriedades mecânicas e baixo custo. Por sua grande utilização e demanda crescente em novas aplicações com exigências mais severas de propriedades mecânicas, a influência dos parâmetros do processo e do tratamento térmico subsequente no comportamento mecânico deve ser mais bem estudada. Com o objetivo principal de caracterizar o aço ao boro DIN 39MnCrB6-2, construiu-se o diagrama de fases metaestável através de simulação, a curva de ductilidade a quente e avaliou-se a influência da temperatura de revenimento na microestrutura e nas propriedades mecânicas de tração e resistência ao impacto. Para isso, utilizou-se amostras de barras laminadas cedidas pela GERDAU - Aços Especiais Brasil de Pindamonhangaba - SP. O montante de amostras utilizadas pôde ser dividido em duas bitolas distintas: quadrada de 155 mm (grupo G1) e redonda de 34,93 mm (grupo G2). Estas amostras foram submetidas a tratamento de têmpera e revenimento e tiveram as propriedades mecânicas de tração, resistência ao impacto e dureza analisadas. Estas amostras foram caracterizadas por microscopia óptica e microscopia eletrônica de varredura. As amostras de seção transversal quadrada de 155 mm foram utilizadas para análises químicas para identificação de segregação e para a construção das curvas de ductilidade a quente. Nas amostras do grupo G1, observou-se segregação inversa de carbono e bons resultados de ductilidade a quente. As amostras de seção transversal redonda apresentaram diferenças significativas em propriedades de tração (Limite de Resistência e Tensão de Escoamento) e dureza mas não apresentaram diferença significativa em resistência ao impacto em baixas temperaturas (-40°C) em função da temperatura de revenimento. A região de fratura do corpo de prova ensaiado e foram encontrados borocarbonetos de menor dimensão. Foram obtidos bons resultados de resistência ao impacto em temperatura ambiente nas amostras temperadas e revenidas que se mantiveram mesmo com a normalização anterior ao tratamento térmico. Conclui-se que a formação de borocarbonetos é inerente aos aços ao boro e o seu crescimento deve ser evitado a fim de diminuir os pontos de fragilização na microestrutura. / Boron added steels in quenched and tempered condition have been used in a large number of applications with mechanical properties and low cost requirements, i.e., automotive, petrochemical and O&G industries. For its great use and increasing demand for new applications with more severe requirements for mechanical properties, it is important to study the influence of process parameters and subsequent heat treatment on the mechanical behavior. In order to characterize the boron steel DIN 39MnCrB6-2, the metastable phase diagram and the hot ductility curve were built. The influence of tempering temperature on the microstructure and mechanical properties of tensile and impact strength was studied. For this study, DIN 39MnCrB6-2 rolled steel bars samples were used. They were provided by Gerdau - Specialty Steel Brazil Pindamonhangaba - SP. The samples could be divided into two different diameters and cross sections: square 155 mm (G1) and round 34.93 mm (G2), from sequential steps of manufacturing process. These samples were quenched and tempered and the tensile mechanical properties, impact resistance (Charpy V-notch) and hardness were analyzed. These samples were also characterized by optical microscopy and scanning electron microscopy. Samples from the first step of rolling mill (square 155 mm) were used for chemical analysis to identify the segregation pattern and also to hot ductility tests. In samples G1 it was observed inverse segregation of carbon and no abnormal ductility loss in hot ductility test. Impact resistance results showed low absorbed energy for all tempering temperatures. Microscopy observation showed coarse borocarbides. Samples G2 showed significant differences in tensile properties and hardness related to tempering temperature. However, no significant differences in impact resistance (CVN) at low test temperatures (-40 ° C) were observed. Microscopy observation showed thin borocarbides. It was concluded that the formation of borocarbides is inherent in boron steels and their coarse morphology should be avoided in order to reduce embrittlement. Borocarbide morphology control is more effective to improve impact resistance than reduction ratio.

Eighteen field plots at 15 locations were selected throughout the state to evaluate the status of the boron content in irrigation waters, soils, and alfalfa (Medicago sativa) plant tissue under irrigated conditions. No boron deficiency symptoms were observed in any of the alfalfa plants at any of these locations, nor were any of the plant tissue boron levels inadequate. Only two locations were found in which the alfalfa plants exibited toxicity symptoms. These locations were along the Indian and Antelope Creeks in Duchesne County which contain high boron levels in the water. All the alfalfa and soil tested and irrigated by either Indian or Antelope Creek waters are the only ones tested and found to contain, naturally occuring, high levels of boron in Utah. The light sandy soils were found to contain less available boron than the heavier clay soils. The sandy soil of the Grand County location at Moab showed no available soil boron, while the clayey soils in Duchesne County irrigated with high boron waters were the only soils found to contain excessive levels of available soil boron. The application of 2.8 kilograms of boron per hectare in the form of Solubor significantly increased the available soil boron content by 19.07 percent in the Cache County plots. The 12 alfalfa varieties grown in the Morgan and Tooele County plots showed significant differences with respect to location and tissue boron contents when the results of the two locations were combined. Overall, variety desert had the highest average boron content of 69.5 milligrams boron per kilogram and AS-49R contained the lowest boron content (Y=69.91+13.64X; R2=0.79) or the available soil boron content (Y=63.15+7.66X; R2=0.82).

Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Sciences, Systems Science and Industrial Engineering Department, 2006. / Includes bibliographical references.

No description available.

<p>To further develop cancer therapy, targeted delivery of cell killing agents directly to tumor cells is an interesting approach. This thesis describes the development of PEG-stabilized liposome conjugates targeting either epidermal growth factor receptor (EGFR) using its natural ligand EGF, or human epidermal growth factor receptor 2 (HER-2) using the antibody trastuzumab. Both receptors are known to be overexpressed on a variety of tumors. The liposomes were loaded with the boronated compounds water soluble boronated acridine (WSA) or water soluble boronated phenantridine (WSP), compounds primarily developed for boron neutron capture therapy, BNCT. </p><p>The liposome conjugates bound specifically to their receptors in cell culture. Because the WSA conjugates exhibited the most favorable boron uptake this compound was chosen for further study. The WSA-loaded liposome conjugates was internalized, an important characteristic for BNCT, and had a long retention inside the cells. The cellular localization of WSA, studied using fluorescence was found to be mainly cytoplasmic. </p><p>To increase the boron uptake studies comparing different incubation methods was performed. It was shown for both EGF and trastuzumab targeted liposomes the uptake could be increased over 10 times by changing from incubation in monolayer culture to incubation in cell suspension in roller flasks. With this treatment the boron concentrations reached after 24 h incubation time was 90 ppm for EGF-liposomes and 132 ppm for trastuzumab-liposomes, levels that are clinically interesting. </p><p>To study the cell-killing efficacy of the liposome-conjugates an experimental BNCT study was performed using EGF-liposome-WSA on cultured glioma cells. About half the number of thermal neutron was needed to inactivate 90% of the cells if the cells had been incubated with EGF-liposome-WSA compared to control cells. When comparing the survival to dose it was shown that to inactivate 90% of the cells 2.9 Gy was needed for EGF-liposome-WSA and neutrons compared to 5.6 Gy with ¹³⁷Cs gamma. </p><p>The biodistribution of EGF-liposomes was also studied in mice. It was compared to EGF and it was found that the addition of a PEG-stabilized liposome to EGF significantly reduced EGF uptake in liver and kidneys, the circulation time in blood was prolonged as well. The reduced liver uptake might be due to inability of the 100 nm liposomes to pass the sinusoidal fenestrations of the liver and bind to the EGFR-rich hepatocytes. The reduced liver uptake potentates the use of EGF-liposome conjugates for systemic injection.</p>

The cell survival curve is the only means by which to both qualitatively and quantitatively assess morphologic alterations directly resulting from in vitro irradiation of the cell. A ������Co cell survival curve experiment has successfully demonstrated the response of the AtT-20 clone mammalian cell line to the effects of gamma rays. With the results of this experiment, a low LET radiation cell survival curve now exists to be used as a comparative upon the completion of BNCT cell survival curves. / Graduation date: 1995

To further develop cancer therapy, targeted delivery of cell killing agents directly to tumor cells is an interesting approach. This thesis describes the development of PEG-stabilized liposome conjugates targeting either epidermal growth factor receptor (EGFR) using its natural ligand EGF, or human epidermal growth factor receptor 2 (HER-2) using the antibody trastuzumab. Both receptors are known to be overexpressed on a variety of tumors. The liposomes were loaded with the boronated compounds water soluble boronated acridine (WSA) or water soluble boronated phenantridine (WSP), compounds primarily developed for boron neutron capture therapy, BNCT. The liposome conjugates bound specifically to their receptors in cell culture. Because the WSA conjugates exhibited the most favorable boron uptake this compound was chosen for further study. The WSA-loaded liposome conjugates was internalized, an important characteristic for BNCT, and had a long retention inside the cells. The cellular localization of WSA, studied using fluorescence was found to be mainly cytoplasmic. To increase the boron uptake studies comparing different incubation methods was performed. It was shown for both EGF and trastuzumab targeted liposomes the uptake could be increased over 10 times by changing from incubation in monolayer culture to incubation in cell suspension in roller flasks. With this treatment the boron concentrations reached after 24 h incubation time was 90 ppm for EGF-liposomes and 132 ppm for trastuzumab-liposomes, levels that are clinically interesting. To study the cell-killing efficacy of the liposome-conjugates an experimental BNCT study was performed using EGF-liposome-WSA on cultured glioma cells. About half the number of thermal neutron was needed to inactivate 90% of the cells if the cells had been incubated with EGF-liposome-WSA compared to control cells. When comparing the survival to dose it was shown that to inactivate 90% of the cells 2.9 Gy was needed for EGF-liposome-WSA and neutrons compared to 5.6 Gy with 137Cs gamma. The biodistribution of EGF-liposomes was also studied in mice. It was compared to EGF and it was found that the addition of a PEG-stabilized liposome to EGF significantly reduced EGF uptake in liver and kidneys, the circulation time in blood was prolonged as well. The reduced liver uptake might be due to inability of the 100 nm liposomes to pass the sinusoidal fenestrations of the liver and bind to the EGFR-rich hepatocytes. The reduced liver uptake potentates the use of EGF-liposome conjugates for systemic injection.

This thesis describes the development of new catalytic methods for the synthesis and application of organometallic reagents, mainly focusing on allylboronic acid derivatives. Thus, palladium pincer-complex catalysis has been applied for extending the scope of palladiumcatalyzed borylation reactions in the synthesis of regio- and stereodefined functionalized allylboronic acid derivatives. These novel allylboronic acids were also employed as substrates in palladium catalyzed regioselective coupling reactions with iodobenzenes. We have also developed a new one-pot sequence based on preparation of allyl- and vinylboronates via catalytic carbon-hydrogen bond activation/borylation reactions. The synthetic scope of the reaction as well as mechanistic studies on the borylation process are presented. Finally, the synthesis of new chiral palladium pincer-complexes is described. These species were employed as catalysts in asymmetric electrophilic allyation of imines.

Successful operation of Nano-ElectroMechanical Systems (NEMS) critically depends on their working environment and component materials' electromechanical properties. It is equally important that ambient or liquid environment to be seriously considered for NEMS to work as high sensitivity sensors with commercial viabilities. Firstly, to understand interaction between NEMS oscillator and fluid, transfer function of suspended gold nanowire NEMS devices in fluid was calculated. It was found that NEMS's resonance frequency decreased and energy dissipation increased, which constrained its sensitivity. Sensitivity limit of NEMS oscillators was also considered in a statistical framework. Subsequently, suspended gold nanowire NEMS devices were magnetomotively actuated in vacuum and liquid. Secondly, electromechanical properties of gold nanowires were carefully studied and the observed size effect was found to agree with theory, which predicted small changes of electromechanical property compared with bulk gold materials. Finally, it is well recognized that continuous development of new NEMS devices demands novel materials. Mechanical properties of new two-dimensional hexagonal Boron Nitride films with a few atomic layers were studied. Outlook of utilizing ultrathm BN films in next generation NEMS devices was discussed.

Several nanomaterials systems, both inorganic and organic in nature, have been extensively investigated by a number of characterization techniques including atomic force microscopy (AFM), electron microscopy, Fourier transform infrared spectroscopy (FTIR), and energy dispersive x-ray spectroscopy (EDX). The first system consists of boron nitride nanotubes (BNNTs) synthesized via two different methods. The first method, silica-assisted catalytic chemical vapour deposition (SA-CVD), produced boron nitride nanotubes with different morphologies depending on the synthesis temperature. The second method, growth vapour trapping chemical vapour deposition (GVT-CVD), produced multiwall boron nitride nanotubes (MWBNNTs). The bending modulus of individual MWBNNTs was determined using an AFM three-point bending technique, and was found to be diameter-dependent due to the presence of shear effects. The second type of nanomaterial investigated is the biomineralized calcareous shell of the serpulid Hydroides dianthus. This material was found to be an inorganic-organic composite material composed of two different morphologies of CaCO3, collagen, and carboxylated and sulphated polysaccharides. The organic components were demonstrated to mediate the mineralization of CaCO3 in vitro. The final system studied is the proteinaceous cement of the barnacle Amphibalanus amphitrite. The secondary structure of the protein components was investigated via FTIR, revealing the presence of β-sheet conformation, and nanoscale rod-shaped structures within the cement were identified as β-sheet containing amyloid fibrils via chemical staining. These rod-shaped structures exhibited a stiffer nature compared with other structures in the adhesive, as measured by AFM nanoindentation.