A series of experimental studies was performed to investigate two separate fluid impingement flow systems intended for removal of particles from a surface or deposition of particles onto a surface. One of these flow systems is generated using a nozzle that incorporates both tilted jets and suction to create what we call a "bounded vortex flow", consisting of an annular swirling jet and a wall-normal vortex with axial upflow into a suction outlet. The other flow system is generated by a combination of acoustic streaming and substrate heating from an ultrasonic source. The primary methods used in the study for flow field measurements included laser-induced fluorescence (LIF) and particle-image velocimetry (PIV). Thermocouples are utilized for gathering temperature information from the ultrasonic induced flow. For the bounded vortex flow, different jet/suction flow rates and different nozzle-substrate separation distances were examined. In the acoustic-generated flow system, different acoustic intensities and transducer-substrate separation distances and different choices of substrate material were examined. Both flow systems achieve high levels of shear stress on the impingement surface via a combination of flow oriented toward and/or away from the surface and via formation of vortex structures near the impingement surface. In the bounded flow configuration, the vortex flow is oriented with axis normal to the impingement surface, whereas in the acoustic-generated flow a series of vortex rings form with axes parallel to the impingement surface. For both flow fields, conditions are observed with high impingement surface shear stress that are well suited to particle removal from the impingement surface. However, as the variables controlling the flows are varied, other conditions are observed in which the flow fields become unstable, leading to oscillatory flows that generally have much smaller shear stress values on the impingement surface. The rate of fluid mixing, as characterized by upward and downward flows normal to the impingement surface, is also generally decreased after these flow transitions have occurred, implying that the unstable flows will be less suited for both particle deposition on and particle removal from the impingement surface.

This study aimed to understand the processes that govern free surface behaviour in depth-limited turbulent flows. Experimental data has shown that the turbulence properties at a point near the free surface relate directly to the properties of the free surface pattern. This would suggest a direct linkage between the free surface and the underlying turbulence field, but this cannot be true since the free surface pattern is strongly dynamic while the sub-surface turbulence field is relatively persistent. An oscillatory spatial correlation function was derived which explains the de-linkage, showing that the turbulence-generated surface pattern periodically inverts as it advects downstream. A model was developed, which shows that the observed free surfaces can be considered as an ensemble of overlapping but behaviourally independent oscillons. These are shown to influence a zone of fluid beneath the surface and invert at a frequency which is a function of the root-mean-square roughness height of the free surface. The spatial frequency of free surface oscillation relates strongly to the spatial frequency of turbulent structures, suggesting that the oscillon motion may form the trigger for near-bed bursting events. Given these relationships, it is proposed that measurement of the free surface behaviour may allow remote measurement of flow conditions. An acoustic wave probe was developed, which is able to remotely recover the key features of the water surface pattern. An array of such probes is proposed for the accurate measurement of temporal and spatial properties of turbulent free surfaces and hence the underlying bulk flow conditions.

A reciclagem agrícola do lodo de esgoto devidamente tratado é uma boa opção, pois transforma o resíduo orgânico em um importante insumo agrícola. Entretanto, a aplicação do lodo de esgoto pode alterar a quantidade e a estabilidade da matéria orgânica do solo. Com a presente pesquisa, objetivou-se avaliar os efeitos de doses de lodo de esgoto na matéria orgânica de dois solos (um Latossolo Vermelho distrófico sob floresta de eucalipto e um Latossolo Vermelho distroférrico sob cultivo de milho) por meio de técnicas quantitativas e espectroscópicas. O experimento I, sob cultivo de milho, foi instalado em Jaguariúna-SP, constituiu-se de 5 doses acumuladas de lodo de esgoto da ETE de Barueri, aplicadas de 1999 a 2005: 0; 30; 60; 120 e 240 t ha-1 (em base seca). O experimento II, sob floresta de eucalipto, foi instalado em dezembro de 2004, em área comercial da empresa da Suzano Papel e Celulose, em Angatuba - SP. Aplicou-se, uma única vez, 4 doses de lodo de esgoto da ETE de Jundiaí (0; 7,7; 15,4 e 23,1 t ha-1 em base seca). Nas amostras de solo foram determinados os conteúdos de carbono, por meio de análise elementar (CHN), e então, calculou-se o grau de humificação da matéria orgânica utilizando a Fluorescência Induzida por Laser (FIL). Com base nesses resultados, foram selecionadas algumas amostras para o fracionamento químico da matéria orgânica do solo e, por meio de técnicas espectroscópicas (FTIR, UV-vis, RMN e Fluorescência de UV-vis), foi realizado um estudo aprofundado da influência do lodo de esgoto nas substâncias húmicas do solo, bem como, em seu estágio de humificação. Pode-se verificar um aumento na concentração de carbono no solo com a aplicação do lodo de esgoto em ambos experimentos, bem como um aumento da alifaticidade e, conseqüentemente, diminuição da aromaticidade das substâncias húmicas, resultado da incorporação de matéria orgânica fresca, não compostada / Agricultural recycling of sewage sludge treated properly is a good option, since it transforms organic waste into a major agricultural input. However, the application of sewage sludge can alter the amount and stability of soil organic matter. The present work aimed to evaluate the effects of sewage sludge levels on organic matter from two different soils (an Oxisol under eucalyptus forest and an Oxisol under corn) through quantitative and spectroscopy techniques. The experiment, under corn, was installed in Jaguariuna-SP, consisted of 5 accumulated levels of sewage sludge from ETE Barueri, implemented from 1999 to 2005: 0, 30, 60, 120 and 240 t ha-1. Experiment II, in eucalyptus forest, was installed in December 2004, the commercial company Suzano Papel e Celulose, in Angatuba - SP. Applied only once, 4 doses of sewage sludge from Seawater Sewage Treatment from Jundiai (0, 7.7, 15.4 and 23.1 t ha-1 on a dry basis). Soil samples were determined carbon content by means of elemental analysis (CHN), and then calculated the degree of humification of organic matter using Laser Induced Fluorescence (LIF). Based on these results, we selected some samples for chemical fractionation of soil organic matter, and by means of spectroscopic techniques (FTIR, UV-vis, NMR and Fluorescence UV-vis), was conducted a detailed study of the influence of sludge sewage humic substances on the ground as well as on their stage of humification. One can observe an increase in the amount of carbon in the soil application of sewage sludge in both experiments, as well as an increase in aliphaticity and consequently decreased aromaticity of humic substances, resulting from the incorporation of fresh organic matter, noncomposted

Made available in DSpace on 2017-07-21T19:25:59Z (GMT). No. of bitstreams: 1 Vanessa Elvira Bonometo.pdf: 1928189 bytes, checksum: 6d3aff421841c38eb85f9fcb925b0243 (MD5) Previous issue date: 2010-06-22 / Stocks and stability of soil organic matter (SOM), even accounting approximately 5% of soil total, are indicators of quality and sustainability of the management system to which the soil is submitted, it has influence on nutrient availability for plants, assists in erosion retention, increases aggregates stability and assists in carbon sequestration. As labile SOM becomes stable through the humification process, affected by climate, soil type and management systems, the molecular structures gain complexity resulting in the formation of groups such as fluorescent aromatic rings and quinines, which can be evaluated by spectroscopy techniques. The purpose of this research was to use spectroscopic techniques to measure the humification of organic matter in a Cambisol, which comes from Irati – PR, submitted to two management systems: conventional tillage and no-tillage (six years and nine years). The forest was used as comparison. Analysis were performed using laser induced fluorescence (LIF) in whole soil (no chemical or physical treatment), and fractions obtained by physical fractionation by granulometry: (clay), (silt) e (fine sand) e (sand). The samples were also analyzed for fluorescence of humic acids, obtained by chemical fractionation of soil and absorption spectroscopy, UV-Visible ( ratio). The results of these tests show no difference in the degree of humification of SOM between management systems. / Os estoques e a estabilidade da matéria orgânica do solo (MOS), mesmo representando cerca de 5% do total do solo, são indicadores da qualidade e da sustentabilidade do sistema de manejo ao qual o solo está submetido, pois tem influência na disponibilidade de nutrientes para as plantas, auxilia na retenção de processos erosivos, aumenta a estabilidade de agregados e auxilia no sequestro de carbono. À medida que a MOS lábil torna-se estável por meio do processo de humificação, afetado pelo clima, tipo de solo e sistemas de manejo, as estruturas moleculares ganham complexidade, resultando na formação de grupos fluorescentes como anéis aromáticos e quinonas, que podem ser avaliados por técnicas espectroscópicas. O objetivo desta pesquisa foi utilizar técnicas espectroscópicas para medir a humificação da matéria orgânica de um Cambissolo Háplico, proveniente do município de Irati – PR, submetidos a dois sistemas de manejo: plantio convencional e plantio direto (de seis e de nove anos). Foi utilizada a mata para comparação. Foram realizadas análises de fluorescência induzida a laser (FIL) nas amostras de solo inteiro (sem nenhum tratamento físico ou químico) e das suas fracões obtidas através de fracionamento físico granulométrico: (argila), (silte) e (areia fina) e (areia grossa). Também foram realizadas análises de fluorescência dos ácidos húmicos, obtidos por meio de fracionamento químico do solo, e espectroscopia de absorção de UV-Visível (razão ). Os resultados desta análise mostram que não houve diferença no grau de humificação da MOS entre os sistemas de manejo.

Made available in DSpace on 2017-07-24T19:38:00Z (GMT). No. of bitstreams: 1 Talita Martins.pdf: 7224778 bytes, checksum: bdb6b8d18dd89284e3b8171f47ce02ad (MD5) Previous issue date: 2009-04-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Organic matter is the main agent present in the soil due to some of its actions, for example: responsible by source of nutrient for the plants, avoid erosive process, improve the aggregates stability, and act as a drain to atmospheric CO2, among others. Therefore, there are same management practice to enforce an increase in the percentage of soil organic matter, increasing the soil quality and the fertility. Among the management systems uses, being conservation management system that increase or keep the same rate of organic matter mainly on the surface, and Conventional Management that use a high rotation and cleanup the soil. In this work were used samples of Distrofic Red Latossol from Ponta Grossa – PR region, at different management systems: Conventional Tillage (CT), Reduced Tillage (RT) and No-Tillage (NT) at 0-5, 5-10, 10-15 and 15-20 cm of depth. Beyond the samples without any treatment (whole soil) it was analyzed parts obtained by granulometric physical fraction according: smaller than 2 μm (clay), between 2-20 μm (silt) and between 20-1000 μm (sand). All the samples were analyzed by X-ray fluorescent (XRF) and Fourier transform infrared (FTIR) and X-ray diffraction. It was determined eleven different mineral in the samples: Cau, Ha, Mt, Gb, Ve, An, Gt, Qz, He, Mag ant Rt. In relation to management systems and depth were not find qualitative different at the minerals. Humification indexes was determined in the soil organic matter by laser induced fluorescent (LIF) and the C/N ratio. CT samples showed larger humification and lower C/N ratio than others systems. In the other hand, NT collected between 0-5 cm depths showed larger percentage of C and lower humification than others systems. Sand fraction showed larger humification than other fractions soil studied. All cases presented lower humification in the superficial samples (0-5 cm depth). NT samples showed more favorable for organic matters accumulated, it was observed due to the difficult to separate the sand fraction from the others fractions by the granulometric physical fraction. / A matéria orgânica é o principal agente constituinte do solo, por ser responsável pela disponibilidade de nutrientes para as plantas, evitar processos erosivos, aumentar a estabilidade dos agregados, agir como um dreno do CO2 atmosférico, entre outras. Portanto, existe uma preocupação em adotar práticas de manejo que favoreçam maiores aportes de matéria orgânica do solo (MOS) e consequentemente aumentando sua qualidade e fertilidade. Entre os sistemas de manejo adotados, estão os sistemas conservacionistas que mantém ou aumentam as taxas de matéria orgânica principalmente na superfície e o plantio convencional que utiliza intenso revolvimento e limpeza do solo. Utilizou-se amostras de Latossolo Vermelho distrófico da região de Ponta Grossa, PR (Campos Gerais) em diferentes sistemas de manejo: plantio direto (PD), plantio convencional (PC) e preparo mínimo (PM) com profundidades 0-5, 5-10, 10-15 e 15-20 cm. Além das amostras de solo inteiro (sem nenhum tratamento físico ou químico) analisou-se também as suas frações obtidas através de fracionamento físico granulométrico: < 2 μm (argila), 2-20 μm (silte) e 20-1000 μm (areia). As amostras de solo inteiro e suas frações foram analisadas mineralogicamente utilizando a espectroscopia de Fluorescência de Raios X (FRX) e Infravermelho com transformada de Fourier (FTIR), além da Difração de Raios X (DRX). Foram determinados onze minerais nas amostras de solo inteiro, Cau, Ha, Mt, Gb, Ve, An, Gt, Qz, He, Mag e Rt. Em relação aos sistemas de manejo e profundidades não foram observadas diferenças qualitativas nos minerais. Para determinar o grau de humificação da MOS utilizou-se a espectroscopia de Fluorescência Induzida por Laser (FIL) e a razão C/N. No geral as amostras de solo inteiro sob PC apresentaram os maiores índices de humificação e menores razões C/N indicando maior humificação em comparação com os demais sistemas de manejo. Em contrapartida, as amostras sob PD e profundidade 0-5 cm foram as que apresentaram maior teor de C e menor grau de humificação. Para as frações do solo, a fração areia apresentou-se como a mais humificada e a fração argila menos humificada. Em todos os casos, as amostras de profundidades menores (0-5 cm) apresentaram menores índices de humificação. O PD mostrou-se favorável à acumulação de matéria orgânica, aumentando a estabilidade dos agregados, fato observado pela maior dificuldade em separar a fração argila das demais frações através do fracionamento físico granulométrico.

A reciclagem agrícola do lodo de esgoto devidamente tratado é uma boa opção, pois transforma o resíduo orgânico em um importante insumo agrícola. Entretanto, a aplicação do lodo de esgoto pode alterar a quantidade e a estabilidade da matéria orgânica do solo. Com a presente pesquisa, objetivou-se avaliar os efeitos de doses de lodo de esgoto na matéria orgânica de dois solos (um Latossolo Vermelho distrófico sob floresta de eucalipto e um Latossolo Vermelho distroférrico sob cultivo de milho) por meio de técnicas quantitativas e espectroscópicas. O experimento I, sob cultivo de milho, foi instalado em Jaguariúna-SP, constituiu-se de 5 doses acumuladas de lodo de esgoto da ETE de Barueri, aplicadas de 1999 a 2005: 0; 30; 60; 120 e 240 t ha-1 (em base seca). O experimento II, sob floresta de eucalipto, foi instalado em dezembro de 2004, em área comercial da empresa da Suzano Papel e Celulose, em Angatuba - SP. Aplicou-se, uma única vez, 4 doses de lodo de esgoto da ETE de Jundiaí (0; 7,7; 15,4 e 23,1 t ha-1 em base seca). Nas amostras de solo foram determinados os conteúdos de carbono, por meio de análise elementar (CHN), e então, calculou-se o grau de humificação da matéria orgânica utilizando a Fluorescência Induzida por Laser (FIL). Com base nesses resultados, foram selecionadas algumas amostras para o fracionamento químico da matéria orgânica do solo e, por meio de técnicas espectroscópicas (FTIR, UV-vis, RMN e Fluorescência de UV-vis), foi realizado um estudo aprofundado da influência do lodo de esgoto nas substâncias húmicas do solo, bem como, em seu estágio de humificação. Pode-se verificar um aumento na concentração de carbono no solo com a aplicação do lodo de esgoto em ambos experimentos, bem como um aumento da alifaticidade e, conseqüentemente, diminuição da aromaticidade das substâncias húmicas, resultado da incorporação de matéria orgânica fresca, não compostada / Agricultural recycling of sewage sludge treated properly is a good option, since it transforms organic waste into a major agricultural input. However, the application of sewage sludge can alter the amount and stability of soil organic matter. The present work aimed to evaluate the effects of sewage sludge levels on organic matter from two different soils (an Oxisol under eucalyptus forest and an Oxisol under corn) through quantitative and spectroscopy techniques. The experiment, under corn, was installed in Jaguariuna-SP, consisted of 5 accumulated levels of sewage sludge from ETE Barueri, implemented from 1999 to 2005: 0, 30, 60, 120 and 240 t ha-1. Experiment II, in eucalyptus forest, was installed in December 2004, the commercial company Suzano Papel e Celulose, in Angatuba - SP. Applied only once, 4 doses of sewage sludge from Seawater Sewage Treatment from Jundiai (0, 7.7, 15.4 and 23.1 t ha-1 on a dry basis). Soil samples were determined carbon content by means of elemental analysis (CHN), and then calculated the degree of humification of organic matter using Laser Induced Fluorescence (LIF). Based on these results, we selected some samples for chemical fractionation of soil organic matter, and by means of spectroscopic techniques (FTIR, UV-vis, NMR and Fluorescence UV-vis), was conducted a detailed study of the influence of sludge sewage humic substances on the ground as well as on their stage of humification. One can observe an increase in the amount of carbon in the soil application of sewage sludge in both experiments, as well as an increase in aliphaticity and consequently decreased aromaticity of humic substances, resulting from the incorporation of fresh organic matter, noncomposted

Capillary electrophoresis laser-induced fluorescence (CE-LIF) is widely used to detect both the presence and concentration of fluorescently labeled biomolecules. In CE-LIF, a plug of sample fluid is electrophoretically driven down a microchannel using a high voltage applied between the opposite ends of the microchannel. Molecules of different sizes and charge states travel at different velocities down the channel. Laser light with a wavelength in the excitation band of the fluorophores is focused near the end of the channel. As each species of molecule passes through the laser spot, the fluorophores emit a fluorescence signal which is measured with an optical detector. Commercial CE-LIF systems are available as a complete, expensive package. Custom CE-LIF systems are a collection of commercially available components that meet the specific needs of the end user. Using the custom system in Dr. Woolley's lab as the standard, we hypothesized that 3D printed parts in conjunction with low-cost components could be used to significantly reduce costs and simplify the system, which in turn would make such systems more widely available with a lower barrier to entry. Testing this hypothesis began with five semesters of small teams of senior undergraduate students trying to design and assemble a low-cost CE-LIF system as part of their mandatory one-semester senior project. I was one of the seniors who worked on the system. Although none of the senior project teams were successful, a partially functioning system was ultimately produced. I reference this system as the starting point system throughout this thesis, which is focused on identifying and solving the system's obstacles in order to reach a working state. I re-designed and re-built each sub-system of the starting point system as needed if within the available budget to create a system that was functional. Budgetary constraints were included in evaluating potential improvements. The end goal was to compare the improved system's performance with that of an expensive conventional system (hereinafter referred to as the standard system) available in Dr. Adam Woolley's laboratory on the Brigham Young University campus. The ultimate conclusion of my masters' thesis work is that a low-cost CE-LIF system based on 3D printed and low-cost components results in a system that does not offer repeatable performance. In the course of my work, many lessons were learned as to what would reduce overall system costs while maintaining a user-friendly experience. My analysis is given on a subsystem basis to explain what limited the ability of the system to run consistently or what caused it to fail altogether. Details and methodology of my contributions including circuits designed, code written, components used, and 3D models printed in order to test the hypothesis are documented. Attribution of the work prior to mine is laid out when each subsystem is broken down in detail for the failure modes that prevented consistent operation. Future work is suggested to correct the problems encountered and provide a path forward to implement a next-generation system that can be achieved at a lower cost compared to a conventional system, and yet which does not suffer from the performance problems associated with the version explored in this thesis in which maximum cost reduction was aggressively pursued.

Les phénomènes physiques pilotant la stabilisation des flammes laminaires partiellement prémélangées sont étudiés à l'appui d'un brûleur domestique modèle. La structure et l'aérodynamique de la flamme sont caractérisées par Fluorescence Induite par Laser sur le radical OH et par Vélocimétrie par Images de Particules. Cette flamme est considérée comme deux flammes doubles adjacentes, chacune constituées d'une extrémité de flamme. La flamme double supérieure a un comportement similaire à une flamme d'un brûleur Bunsen : elle est stabilisée par un mécanisme d'accroche-flamme sur le brûleur et le sommet du cône est stabilisé par l'équilibre de la vitesse du front de flamme et de la vitesse de l'écoulement. La flamme double inférieure se stabilise au croisement de la ligne stœchiométrique et de la ligne iso-vitesse, correspondante à la vitesse de flamme plane stœchiométrique. Cette base inférieure est soufflée lorsque ces deux lignes n'ont plus de point commun.

This thesis is focused on studies of substituted Hg-based superconducting copper oxides ((Hg1-xMx)Ba2Can-1CunO2n+2+δ). These compounds are promising objects of investigation, not only from a fundamental point of view but also because of their high values of superconducting transition temperature (Tc) and irreversibility field (Hirr). The first part of the thesis is devoted to optimization of the synthesis procedure for Hg-based cuprates. The influence of different parameters (T, t, p(Hg), p(O2)) on the synthesis of these compounds in sealed silica tubes was studied. Optimal conditions yielded samples containing up to 95% of HgBa2Ca2Cu3O8+δ (Hg-1223). The formation of solid solutions with the formula (Hg1-xCux)Ba2Ca2Cu3O8+δ (where x &lt;= 0.5) was also established. Another technique was developed, using LiF as a flux, for synthesis of samples containing up to 90% of the HgBa2CaCu2O6+δ (Hg-1212) phase. The second part concerns synthesis and studies of oxyfluorides using Hg-1212 and Hg-1223 as starting materials together with XeF2 as a fluorinating agent. It was found that oxyfluorides of both phases have a parabolic dependence of Tc vs. a parameter as well as enhanced Tc values (ΔT ≈ 3-4 K) in comparison with optimally doped non-fluorinated analogues. The crystal structure of Hg-1223 oxyfluoride was studied by X-ray powder and neutron diffraction methods. It is suggested that chemical modification of the crystal structure leads to a decrease in Cu-O distance without noticeable change in Cu-O-Cu angle (in the (CuO2) layers), which may be the significant factors influencing this Tc increase. Hg-1223 oxyfluoride was also studied under high pressure for first time. It was found that this compound has a record-high Tc value (≈ 166 K) at P ≈ 23 GPa. The last part describes the investigation of substituted Hg-based superconductors in the series (Hg0.9M0.1)Ba2CuO4+δ {(Hg,M)-1201}, where M = Tl, Pb, W, Mo, Nb and V. A comprehensive study of these compounds by various methods (X-ray powder diffraction, EDX, IR-, EXAFS- and XANES -spectroscopy) indicated that the change of charge carrier doping level is a crucial factor determining the irreversibility line. (Hg0.9Mo0.1)Ba2CuO4+δ showed the most improved irreversibility line position among the (Hg,M)-1201 compounds studied in this series.

Bone metabolism is regulated by endocrine and paracrine signalling molecules influencing bone cells in the continuously remodelling bone tissue. These molecules include a variety of osteotropic stimulatory and inhibitory cytokines. Degradation of alveolar bone in periodontal disease is believed to be a result of local release of such osteotropic cytokines, although the relative importance of particular cytokines and their cellular origin is currently unknown. The aim of the present project was to study if, and how, pro-inflammatory cytokines in the interleukin-6 (IL-6) family of cytokines, and anti-inflammatory IL-4 and IL-13 type of cytokines, can affect osteoclast differentiation and bone resorption. Additionally, the objective was to study if gingival fibroblasts may influence alveolar bone resorption through secretion of IL-6 type cytokine release and if the secretion is regulated by pro-inflammatory as well as anti-inflammatory mediators such as IL-4 and IL-13. IL-6 in combination with its soluble receptor (sIL-6R) was found to stimulate mouse calvarial bone resorption. Similarly, two other IL-6 family members, leukemia inhibitory factor (LIF) and oncostatin M (OSM) were found to stimulate bone resorption. The stimulatory effect on bone resorption induced by the three cytokines was associated with increased expression of receptor activator of NF- κB ligand (RANKL), a cytokine which is essential in osteoclast formation and activation through binding to receptor activator of NF- κB (RANK) on osteoclastic cells. The interaction between RANKL and RANK can be inhibited by binding of the decoy receptor osteoprotegerin (OPG) to RANKL, and the expression of OPG was also regulated by IL-6, LIF and OSM (Paper I). The two related cytokines IL-4 and IL-13 were found to inhibit osteoclastogenesis and mouse calvarial bone resorption by mechanisms involving a decreased RANKL/OPG ratio in osteoblasts and decreased RANK expression in osteoclastic cells. The results further demonstrated that IL-4 and IL-13 exert their effects on both osteoblasts and osteoclasts by a mechanism involving the transcription factor signal transducer and activator of transcription 6 (STAT6) (Paper II). Constitutional expression of IL-6, LIF and another member of the IL-6 family of cytokines, IL-11, was demonstrated in human gingival fibroblasts. IL-6 type cytokine expression levels were found to be enhanced by IL-1β and tumour necrosis factor-α (TNF-α) (Paper III), whereas IL-4 and IL-13 inhibited IL 11 and LIF release from gingival fibroblasts (Paper IV). In conclusion, IL 6 type cytokines were found to be stimulators and IL-4 and IL-13 inhibitors of bone resorption in vitro via mechanisms involving RANK/RANKL/OPG interactions. Additionally, gingival fibroblasts were able to secrete several cytokines in the IL-6 family. Secretion was further enhanced by pro-inflammatory mediators and inhibited by IL-4 and IL- 13. These findings support the view that resident cells may influence the pathogenesis of periodontal disease through osteotropic cytokine production.