Phagocytosis is the process by which cells engulf foreign bodies. It is the hallmark behavior of white blood cells, being the process through which those cells ingest and degrade pathogens and debris. To date a large amount of research has focused on documenting the existence and role of biochemical components involved with phagocytosis. Scores of signaling molecules have been implicated in the complex signal cascade which drives the process. These molecules are small (typically no larger than 5 nanometers) and operate in a crowded, chemically “noisy,” environment, yet they coordinate the cell's activity over comparatively expansive distances (as large as 20 micrometers). How these molecular processes scale-up to coordinate the activities of the cell over such massive distances is largely unknown. Using a planar analog of phagocytosis termed “frustrated phagocytosis,” we experimentally demonstrate that phagocytosis occurs in three distinct phases: initial cell-antigen binding, symmetric spreading, and late-stage contraction. Initial binding and symmetric spreading appears to be both mechanically and chemically similar to the quasi-universal cellular behaviors of adhesion and migration. Adhesion and migration have received extensive attention from the biophysics community in recent years. Leveraging these similarities, we adapt the biomechanical frameworks used in models of migration to phagocytosis. We show that macroscopic properties such as a cell's effective viscosity and membrane cortical tension can be used to model cell behavior during phagocytosis. Our experiments reveal that late-stage contraction distinguishes frustrated phagocytosis from other spreading behaviors. This contraction is myosin dependent. Additionally we demonstrate, for the first time, that late-stage contraction corresponds with formation of a contractile F-actin belt. Based on the dynamic contraction model (DC) developed to explain actin structure during cell migration we propose a DC model of phagocytosis which posits that contractile belt formation is the result of a late-stage myosin activity coupled with F-actin.

Made available in DSpace on 2015-03-26T13:23:49Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1550233 bytes, checksum: d4d097877e07cf41cd16798df4a21906 (MD5) Previous issue date: 2013-02-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The importance of Brazilian agriculture in the global scenario is closely related to the expansion of the agricultural frontier throughout the country in recent decades. This process occurred through the use of new techniques, processes and equipment that allowed the expansion of crops for areas previously considered unsuitable. The tractor had an instrumental role in jump national agriculture and can be considered the main source of power in the field. The use of tractors in production enhances the quality of service performed and ensures achieving greater operational efficiency at all stages of production. The tractor is a complex machine, comprising a number of elements and mechanisms which operate concurrently to ensure basic function of a tractor, in other words, provide power for agriculture. The performance of a machine in traction is affected by several variables such as the internal pressure of the tires and weight transfer. Thus, the aim of this work was to evaluate the following questions: Influence of the internal pressure of the tires and the slope of the line traction in operating parameters and the mechanical vibration of the base station operation; Change in the internal pressure of the tire dynamic condition due to the weight transfer between front and rear axle. Work was done on the campus of the Federal University of Viçosa, in the period from March to August 2012. The experiment conducted to determine the performance and vibration in the post of operation was performed in firm ground track, and the treatments of the combination of three tire inflation pressure (12, 14 and 16 psi), three inclinations of traction line and four traction forces (3.57, 6.86, 12.46 and 16.23 kN), in a completely randomized design, with eight replications. The experiment conducted to evaluate the variation of the internal pressure of the tires in dynamic condition was performed on concrete track, with four treatments consisting of traction forces of 4.44, 14.57, 18.6 and 23.92 kN, in a completely randomized design, with four replications. We used a tractor with front wheel assist, equipped with bias tires and a set of transducers for measuring the parameters of interest. The results showed that the slip of wheelsets of the tractor increased progressively with increasing traction force, that reducing the internal pressure of the tires caused a reduction in the slip of the wheelsets in the greatest traction forces and that the inclination of the line traction had significant effect only for the tensile strength of 16.23 kN. The hourly fuel consumption increased by about 65% with increasing tensile strength of 3.56 to 16.23 kN, the internal pressure of the tires and the class of inclination of the line traction had limited effect on this variable. The traction force and the internal pressure of the tire exerted a positive effect on levels of longitudinal vibration at the base of the post operating, the highest levels were observed for the combination of tensile strength of 16.23 kN and the internal pressure of 110,32 kPa, with values close to 0,61 m s-2, and the lowest for the force of 3,56 kN and 82,74 kPa pressure, with values close to 0,20 m s-2. The traction force and the internal pressure of the tires had a quadratic effect on vibration levels in the vertical direction at the base of the post operating, the highest levels were observed for the combination of traction force of 16,23 kN and the internal pressure of 110,32 kPa, with values close to 0.75 m s-2, and the lowest for the force of 3,56 kN combined with the internal pressure of the tires of 82,74 kPa. The variation of weight transfer acting on each axle of the tractor was able to provide the change in the internal pressure of tires in dynamic condition. The traction force showed a linear variation of the internal pressure of the tire during the development of tensile, being generated model considered valid to estimate the traction force from the variation of the internal pressure of the tires. / A importância da agricultura brasileira no cenário mundial está intimamente relacionada com a ampliação da fronteira agrícola ao longo do território nacional nas últimas décadas. Esse processo ocorreu mediante a utilização de novas técnicas, processos e equipamentos que permitiram a expansão dos cultivos para áreas antes consideradas impróprias. O trator agrícola teve papel fundamental no salto da agricultura nacional e pode ser considerada a principal fonte de potência no campo. A utilização de tratores na produção aprimora a qualidade do serviço realizado e garante a obtenção de maior rendimento operacional em todas as etapas da produção. O trator é uma máquina complexa, composta de uma série de mecanismos e elementos que operam concomitantemente para garantir a função básica de um trator, ou seja, fornecer potência para a agricultura. O desempenho de uma máquina em tração é afetado por diversas variáveis como a pressão interna dos pneus e a transferência de peso. Deste modo, objetivou-se com esse trabalho avaliar os seguintes quesitos: Influência da pressão interna dos pneus e da inclinação da linha de tração nos parâmetros operacionais e nas vibrações mecânicas na base do posto de operação; Alteração da pressão interna dos pneus em condição dinâmica decorrente da transferência de peso entre o eixo dianteiro e traseiro. Os trabalhos foram executados no campus da Universidade Federal de Viçosa, no período de março a agosto de 2012. O experimento conduzido para determinar o desempenho e a vibração no posto de operação foi realizado em pista de solo firme, sendo os tratamentos constituídos da combinação de três pressões internas dos pneus (12, 14 e 16 psi), três inclinações da linha de tração e quatro forças de tração (3,57; 6,86; 12,46 e 16,23 kN), no delineamento inteiramente casualizado, com oito repetições. O experimento conduzido para avaliar a variação da pressão interna dos pneus em condição dinâmica foi realizado em pista de concreto, com quatro tratamentos constituídos das forças de tração de 4,44; 14,57; 18,6 e 23,92 kN, no delineamento inteiramente casualizado, com quatro repetições. Foi utilizado um trator agrícola com tração dianteira auxiliar, equipado com pneus diagonais e um conjunto de transdutores para mensurar os parâmetros de interesse. Os resultados demonstraram que o deslizamento dos rodados do trator aumentou progressivamente com o aumento da força de tração, que a redução da pressão interna dos pneus promoveu a redução do deslizamento dos rodados nas maiores forças de tração e que a inclinação da linha de tração apresentou efeito significativo apenas para a força de tração de 16,23 kN. O consumo horário de combustível aumentou cerca de 65% com o aumento da força de tração de 3,56 para 16,23 kN, a pressão interna dos pneus e a classe de inclinação da linha de tração apresentaram efeito reduzido sobre essa variável. A força de tração e a pressão interna dos pneus exerceram efeito positivo nos níveis de vibração longitudinal na base do posto de operação, sendo que os maiores níveis foram observados para a combinação entre a força de tração de 16,23 kN e a pressão interna de 110,32 kPa, com valores próximos a 0,61 m s-2, e as menores para a força de 3,56 kN e pressão de 82,74 kPa, com valores próximos a 0,20 m s-2. A força de tração e a pressão interna dos pneus apresentaram efeito quadrático nos níveis de vibração no sentido vertical na base do posto de operação, sendo os maiores níveis observados para a combinação entre a força de tração de 16,23 kN e a pressão interna de 110,32 kPa, com valores próximos a 0,75 m s-2, e as menores para a força de 3,56 kN combinada com a pressão interna dos pneus de 82,74 kPa. A variação da transferência de peso atuando sobre cada eixo do trator foi capaz de propiciar a alteração da pressão interna dos pneus em condição dinâmica. A força de tração apresentou efeito linear na variação da pressão interna dos pneus durante o desenvolvimento de tração, sendo o modelo gerado considerado válido para estimar a força de tração a partir da variação da pressão interna dos pneus.

O preparo inicial do solo tem grande importÃncia para a produÃÃo agrÃcola, essa atividade à geralmente realizada por traÃÃo animal na agricultura familiar. Nesse trabalho estudou-se a utilizaÃÃo de tratores de rabiÃas como fonte de otimizaÃÃo do trabalho no campo. O experimento foi desenvolvido com um trator de rabiÃas com um arado acoplado na Universidade Federal do Cearà com o objetivo de avaliar a eficiÃncia energÃtica do trator de rabiÃas acoplado ao arado de disco utilizando trÃs marchas (1Â, 2 e 3Â) em um Argissolo Vermelho Amarelo, avaliou-se tambÃm o empolamento do solo e os nÃveis de ruÃdo com a mÃquina parada em diferentes raios de afastamento (1, 2, 5 e 10 m), e com o trator de rabiÃas em movimento utilizando trÃs rotaÃÃes (810, 1.040 e 1.360 rpm). Para obtenÃÃo de dados sobre a eficiÃncia energÃtica utilizou-se um trator de rabiÃas, instrumentado com sensores indutivos nas rodas para medir a patinagem dos rodados, fluxÃmetro para medida do consumo de combustÃvel e cÃlula de carga para obtenÃÃo da forÃa de trabalho na barra de traÃÃo. Para instalar a cÃlula de carga e obter estabilidade do implemento foi necessÃrio utilizar um comboio, onde o conjunto percorria um espaÃo 25 m com trÃs repetiÃÃes em cada marcha para as coletas dos dados. O empolamento do solo foi calculado atravÃs de dados obtidos com o perfilometro no campo e os nÃveis de ruÃdo foram medidos com dosÃmetro e decibelimetro. As variÃveis estudadas foram consumo horÃrio de combustÃvel (L.h-1), consumo especÃfico de combustÃvel (g.kW.h-1), patinagem dos rodados (%), forÃa de traÃÃo na barra (kN), velocidade de trabalho (m.s-1) e potÃncia disponÃvel (kW). Esses dados foram avaliados com o arado realizando trabalho e com o implemento erguido para ser feito de comparaÃÃo calculou-se as diferenÃa (resultados com o implemento arando, menos os resultados com o arado sem realizar trabalho), para estudo das mÃdias obtidas. A anÃlise dos dados foi realizada utilizando estatÃstica descritiva utilizando o programa computacional Assistat 7.6 beta. Os resultados mostraram que os valores mÃdios da patinagem foram de 10 % (1 marcha), 12 % (2 marcha) e 18 % (3 marcha). Os valores mÃdios encontrados para o arado realizando trabalho para o consumo horÃrio de combustÃvel foi de 5,45 L.h-1 (1 marcha), 4,22 L.h-1 (2 marcha) e 2,54 L.h-1 (3 marcha); o consumo especÃfico de combustÃvel foi de 3004,98 g.kW.h-1 (1 marcha), 4343,88 g.kW.h-1 (2 marcha) e 5787,91 g.kW.h-1 (3 marcha); a potÃncia foi de 1,54; 0,83 e 0,38 kW para a 1Â, 2 e 3 marcha respectivamente e as mÃdias da velocidade de deslocamento foram de 0,32 m.s-1 (1 marcha), 0,41 m.s-1 (2 marcha) e 0,44 m.s-1 (3 marcha). Os valores mÃdios encontrados para o momento em que o arado nÃo realizava trabalho, ou seja, o implemento estava erguido foi para o consumo horÃrio de combustÃvel de 6,58 L.h-1 (1 marcha), 5,98 L.h-1 (2 marcha) e 4,20 L.h-1 (3 marcha); o consumo especÃfico de combustÃvel apresentou valores de 3514,09 g.kW.h-1 (1 marcha), 4728,22 g.kW.h-1 (2 marcha) e 5787,91 g.kW.h-1 (3 marcha); a potÃncia foi de 1,54 kW (1 marcha), 0,83 kW (2 marcha) e 0,38 kW (3 marcha) e as mÃdias da velocidade de deslocamento foram de 0,27; 0,33 e 0,40 m.s-1 para a 1Â, 2 e 3 marchas respectivamente. O empolamento do solo chegou a 75 % (2 marcha) e obteve valores de aproximadamente 64 % para a 1 e 3 marcha. E os nÃveis de ruÃdo encontrados utilizando o dosimetro foram de 95,7 dB(A) (1 marcha), de 98,2 dB(A) (2 marcha) e 98,8 dB(A) (3 marcha). Os nÃveis mÃdios de ruÃdo encontrados com o auxilio do decibelimetro foi de 76,71; 77,38 e 80,80 dB(A) para as rotaÃÃes de 810, 1.040 e 1.360 rpm respectivamente. Recomenda-se o uso de protetores auriculares ou a diminuiÃÃo da carga horÃria de trabalho para o operador que esteja trabalhando diretamente com o trator de rabiÃas. / The initial tillage has great importance for agricultural production. This activity is usually performed by animal traction in family farming. In this paper, we studied the use of handlebar tractors as a source for field work optimization. The experiment was conducted with a handlebar tractor with a plow attached to it at the Federal University of CearÃ. The goal was to evaluate the energetic efficiency of the handlebar traitor attached to the disc plow, using three gears (1st, 2nd, 3rd) in a red, yellow argisoil. It was also evaluated the soil shoaling and the noise levels with the machine both stopped in different rays of distances (1, 2, 5 and 10 meters), and with handlebar traitor in movement, using three different number of turns (810, 1040 and 1360 rpm). To obtain data about energetic efficiency, it was used a handlebar traitor, an instrument with inductive sensors on wheels to measure the wheelsets slippage, a flowmeter to measure the fuel consumption and a loading cell to obtain the workforce in the drawbar. To install the loading cell and obtain the implement stability, it was necessary to use a train, in which the set traveled 25m with three repetitions in each gear to the collecting of the data. The soil shoaling was calculated through the data obtained in the field by a profilometer, and the levels of noise were measured with a dosimeter and a decibelimeter. The studied variables were the hourly fuel consumption (L.h-1), the specific fuel consumption, (g.kW.h-1), the wheelsets slippage (%), traction force in the bar (kN), work speed (m.s-1) and available power (kW). These data were evaluated with the plow working and with the implement raised to be compared. We calculated the difference (results with the implement plowing minus the results with the plow not working) to study the obtained averages. Data analysis was performed using descriptive statistics using the computer program Assistat 7.6 beta. The results showed that the average rates of slippage were 10% (1st gear), 12 % (2nd gear) and 18% (3rd gear). The average rates for the plow while it was working for the hourly fuel consumption were 5,45 L.h-1 (1st gear), 4,22 L.h-1 (2nd gear) and 2,54 L.h-1 (3rd gear); the specific fuel consumption was 3004,98 g.kW.h-1 (1st gear), 4343,88 g.kW.h-1 (2nd gear) and 5787,91 g.kW.h-1 (3rd gear); the power was 1,54; 0,83 and 0,38 kW for 1st, 2nd and 3rd gear respectively, and the movement speed averages were 0,32 m.s-1 (1st gear), 0,41 m.s-1 (2nd gear) and 0,44 m.s-1 (3rd gear). The average rates for the hourly fuel consumption that were found for the moment when the plow was not working, that is, the implement was raised, were 6,58 L.h-1 (1st gear), 5,98 L.h-1 (2nd gear) and 4,20 L.h-1 (3rd gear); the rates for the specific fuel consumption were 3514,09 g.kW.h-1 (1st gear), 4728,22 g.kW.h-1 (2nd gear) and 5787,91 g.kW.h-1 (3rd gear); the power was 1,54 kW (1st gear), 0,83 kW (2nd gear) and 0,38 kW (3rd gear), and the movement speed averages were 0,27; 0,33 and 0,40 m.s-1 for 1st , 2nd and 3rd gears respectively. The soil shoaling achieved the rates 75 % (2nd gear) and, approximately, 64 % for the 1st and 3rd gears. And the levels of noise that were found by the usage of the dosimeter were 95,7dB(A) (1st gear), 98,2dB(A) (2nd gear) and 98,8 dB(A) (3rd gear). The average levels of noise that were found by the usage of the decibelimeter were 76,71; 77,38 and 80,80 dB(A) for the turns 810, 1.040 e 1.360 rpm respectively. It is advised the use of headphones or the decreasing of the working hours for the operator who is working directly with the tractor handlebars.

In biomechano-transducing, cellular generated tension can be measured by soft substrates based on polymers but these techniques are limited either by spatial resolution or ability to detect localised cell traction forces (CTF) due to their non-linear viscous behaviour under shear rates. A newly developed cell traction force transducer system based on cholesteryl ester lyotropic liquid crystals (LCTFT) was developed to sense localised traction forces of human keratinocyte cell lines (HaCaTs), in which the length of the deformation line induced represents the intensity of the CTF exerted. The physical properties of the cholesteryl ester based lyotropic liquid crystals (LLC) were characterised by using polarising microscopy, rheology, atomic force microscopy (AFM) based nano-indentation, spherical indentation, and micro-tensile tests. The interactions of LLC with cells were studied by using cell viability studies, cytochemical treatments, widefield surface plasmon resonance (WSPR) microscopy and various immuno-staining techniques. The results show that LLC is thermally stable (0 - 50 oC) and linearly viscoelastic below 10 % shear strain at shear rates of < 1 s-1. AFM nano and spherical indentations show a good agreement on the Young¿s modulus of both determined at ~110 kPa which is close to the elastic modulus of the epidermis. The Poisson¿s ratio of LLC was determined at ~0.58 by using micro tensile tests. The biophysical interaction studies indicated that LLC is biocompatible and allowed cell attachment. Cell relaxation technique by cytochalasin-B treatment suggested that the attachment and contraction of cells on LLC was due to the contractile activity of actin cytoskeletons that are mediated by focal adhesions. The staining experiments showed that cells consistently expressed the same suites of integrins (¿2, ¿3, ¿5 and ¿1) and ECM proteins (collagen type IV, laminin and fibronectin) on both glass and LLC coated substrates. Interfacial interaction of cells with LLC observed via the staining of actin and vinculin, and WSPR imaging suggest the association of marginal actin filaments and focal adhesions in attaching HaCaT cells to the LLC. Linear static analysis applied in the Finite Element model of focal adhesion-LC confirmed the compressive force patterns induced by cells. By applying cell relaxation techniques and Hooke¿s theorem, the force-deformation relationships of the LLC were derived and used for direct quantification of CTF in culture. The sensitivity of the LCTFT was implied by a wide range of CTF (10 - 140 nN) measured at high resolutions (~2 ¿m). Nonetheless, a custom-built cell traction force measurement and mapping software (CTFM) was developed to map CTF of single cells. Reliability of the LCTFT was evaluated by using a known pharmacological active cytokine, TGF-¿1, in inducing contraction of human keratinocytes. This study inferred internal consistency and repeatability of the LCTFT in sensing contraction responses of HaCaT cells in a concentration dependent manner of TGF-¿1. The overall LCTFT and CTFM software had shown good potential for use in the study of contraction and migration of keratinocytes. / Malaysia Ministry of Higher Education

Vacuum assisted delivery (VAD) is a common procedure used in the final stage of labor in the situation of a difficult natural delivery. Since the only biomechanical studies concerning the clinical safe traction force were conducted during 70s using simplified models to mimic the fetal head, concerns remain regarding the side effects of this medical intervention when applying high levels of traction forces. For experimental evaluation of VAD, a tissue-mimicking accurate fetal head phantom, having the same skull and brain dimension as a newborn, as well as, proper mechanical and acoustic properties of materials, can be used as a useful resource in terms of establishing safe levels of traction forces. The goal of this project is to develop a realistic patient-specific fetal head phantom that will be used to investigate the relation between applied traction force and imposed brain deformation in VAD in an experimental setting. A realistic fetal head phantom was developed using geometry accurate segmented meshes of pediatric skull and brain from a CT fetal head dataset. The fetal skull was 3D printed while the segmented mesh of the brain was used to create a fetal brain mold. The fetal brain phantom was developed using a PVA and graphite solution (10% and 3% mass concentration), whereas the sutures and fontanels, the scalp and the cerebrospinal fluid were mimicked using silicone, surgical latex and water, respectively. All the tissue-mimicking materials used corresponded with the biomechanical properties of the fetal head tissues. After the construction of the fetal head phantom, grey-scale long- and short- axis ultrasound images as well as the fetal brain phantom elasticity map were obtained. Furthermore, using sonomicrometry crystals, the reference strain values during manual hand pressure and VAD experimental procedures were acquired. The results showed negative strain values (compression) reaching 15% in the manual pressure experimental procedure, and higher positive strain values (stretching) reaching over 40% in the VAD experimental procedure. However, due to experimental limitations only one measurement using clinically realistic levels for both vacuum pressure (65 kPa) and traction force (70 N) was achieved. The developed fetal head phantom has potential to provide trustful biomechanical evidence to guide safe vacuum assisted delivery as well as to provide useful resource in terms of defining the clinical effective force of the vacuum extractor (VE). / I slutskedet av svåra vaginala förlossningar är assistans med sugklocka vanligt förekommande. Eftersom de enda biomekaniska studierna om kliniskt säkra dragkrafter genomfördes under 70 -talet med hjälp av förenklade modeller för att efterlikna fostrets huvud, finns det fortfarande oro om vilka skador användandet av sugklocka kan leda till när höga dragkrafter används. För att kunna fastställa en säker nivå av dragkrafter skulle en modell av fosterhuvudet, med realistiska dimensioner samt liknande mekaniska och akustiska egenskaper som en nyfödd, kunna användas.  Målet med detta projekt är att utveckla en realistisk patientspecifik modell av fosterhuvudet och sedan använda den för att experimentellt undersöka sambandet mellan applicerad dragkraft och hjärndeformation.  En realistisk fosterhuvudsmodell utvecklades från segmenterade datortomografibilder på ett fosterhuvud. Skallbenet tillverkades med en 3D-skrivare medan hjärnans gjöts i PVA och grafit (10% och 3% masskoncentration) i en 3D-utskriven form. Suturerna och fontanellerna, skalpen och cerebrospinalvätskan efterliknades med silikon, kirurgisk latex respektive vatten. Alla vävnadsimiterande material som användes motsvarade de biomekaniska egenskaperna hos ett fosters huvud.  När modellen var färdigkonstruerad togs ultraljudsbilder i gråskala i både lång- och kortaxel. Även hjärnmodellens elasticitet mättes med ultraljudsbaserad skjuvvågselastografi. Sonomikrometri –kristaller användes för att samla in referensvärden på hjärndeformation vid manuellt handtryck och experimentell rekonstruktion av förlossning med sugklocka. Resultaten visade att negativ deformation (kompression) på 15% i experimentella rekonstruktionen av förlossning. På grund av experimentella begränsningar uppnåddes dock endast en mätning med kliniskt realistiska nivåer för både vakuumtryck (65 kPa) och dragkraft (70 N).  Den utvecklade fosterhuvudsmodellen har i vidare studier potential att tillhandahålla tillförlitliga biomekaniska bevis för att vägleda säker vakuumassisterad förlossning samt för att definiera kliniska effektiva krafter i en sugklocka.

In biomechano-transducing, cellular generated tension can be measured by soft substrates based on polymers but these techniques are limited either by spatial resolution or ability to detect localised cell traction forces (CTF) due to their non-linear viscous behaviour under shear rates. A newly developed cell traction force transducer system based on cholesteryl ester lyotropic liquid crystals (LCTFT) was developed to sense localised traction forces of human keratinocyte cell lines (HaCaTs), in which the length of the deformation line induced represents the intensity of the CTF exerted. The physical properties of the cholesteryl ester based lyotropic liquid crystals (LLC) were characterised by using polarising microscopy, rheology, atomic force microscopy (AFM) based nano-indentation, spherical indentation, and micro-tensile tests. The interactions of LLC with cells were studied by using cell viability studies, cytochemical treatments, widefield surface plasmon resonance (WSPR) microscopy and various immuno-staining techniques. The results show that LLC is thermally stable (0-50 °C) and linearly viscoelastic below 10% shear strain at shear rates of < 1 s⁻¹. AFM nano and spherical indentations show a good agreement on the Young's modulus of both determined at ~110 kPa which is close to the elastic modulus of the epidermis. The Poisson's ratio of LLC was determined at ~0.58 by using micro tensile tests. The biophysical interaction studies indicated that LLC is biocompatible and allowed cell attachment. Cell relaxation technique by cytochalasin-B treatment suggested that the attachment and contraction of cells on LLC was due to the contractile activity of actin cytoskeletons that are mediated by focal adhesions. The staining experiments showed that cells consistently expressed the same suites of integrins (α2, α3, α5 and β1) and ECM proteins (collagen type IV, laminin and fibronectin) on both glass and LLC coated substrates. Interfacial interaction of cells with LLC observed via the staining of actin and vinculin, and WSPR imaging suggest the association of marginal actin filaments and focal adhesions in attaching HaCaT cells to the LLC. Linear static analysis applied in the Finite Element model of focal adhesion-LC confirmed the compressive force patterns induced by cells. By applying cell relaxation techniques and Hooke's theorem, the force-deformation relationships of the LLC were derived and used for direct quantification of CTF in culture. The sensitivity of the LCTFT was implied by a wide range of CTF (10 - 140 nN) measured at high resolutions (~2 μm). Nonetheless, a custom-built cell traction force measurement and mapping software (CTFM) was developed to map CTF of single cells. Reliability of the LCTFT was evaluated by using a known pharmacological active cytokine, TGF-β1, in inducing contraction of human keratinocytes. This study inferred internal consistency and repeatability of the LCTFT in sensing contraction responses of HaCaT cells in a concentration dependent manner of TGF-β1. The overall LCTFT and CTFM software had shown good potential for use in the study of contraction and migration of keratinocytes.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The growing demand for energy that causes the increased traffic of agricultural machinery, larger and more robust, acts negatively on soil compaction, directly and indirectly affecting crop productivity, as many changes in soil physical attributes. As a potential technique to solve this problem has the chiseling, which promotes the disruption of these compacted layers, without causing the inversion of the soil, keeps the plant residues deposited on the surface, improves infiltration, the structure and porosity of the soil and thus facilitates erosion control. However this operation has a high demand for traction. Seeking a more efficient operation of scarification, ie, better utilization of energy, developed and evaluated a tool to break ground in layers simultaneously. For this purpose it was necessary to construct a Structure-Port Mobile Tools capable of performing experimental procedures resulting from the planned treatments. As a mobile source of power was used a Massey Ferguson tractor model MF 275 with 53 kW. The experiment was conducted in the Municipality of Capon Beautiful South, Rio Grande do Sul, in a clayey soil. As a general objective, we sought to answer the following questions: (i) is there any significant difference between chiseling in a single layer or more than one layer, considering the average horizontal force on the drawbar, the specific resistance and the average hourly fuel consumption as criteria for each level of speed? (Ii) how the deepening affects the average horizontal force in the drawbar? And (iii) acts as the advance on the soil area mobilized? Configurations were tested with chiseling of the soil in one, two and three layers, with variations in longitudinal distances between the tips of the spikes. The chiseling treatments in two concurrent 0,15 meters layers and longitudinal distance between the tip ends of 0,30 and 0,40 meters, with one in 0,10 meter of deepening and 0,30 meters advancing presented as the most promising. It was concluded at the end of this work, considering all the tested configurations, there are combinations of deepening, advancing and speed, which proved more efficient than chiseling a single layer. / A crescente demanda de energia que ocasiona o aumento do tráfego de máquinas agrícolas, maiores e mais robustas, atua negativamente na compactação do solo, afetando direta e indiretamente a produtividade das culturas, pois modifica diversos atributos físicos do solo. Como técnica potencial para solucionar este problema tem-se a escarificação, que promove o rompimento dessas camadas compactadas, sem ocasionar a inversão do solo, mantém os resíduos vegetais depositados na superfície, melhora a infiltração, a estrutura e a porosidade do solo e facilita assim o controle da erosão. Contudo esta operação apresenta elevada demanda de tração. Visando uma operação de escarificação mais eficiente, ou seja, com maior aproveitamento de energia, desenvolveu-se e avaliou-se uma ferramenta para o rompimento do solo em camadas, de forma simultânea. Para tanto foi necessária a construção de uma Estrutura Porta-Ferramentas Móvel, capaz de executar os procedimentos experimentais decorrentes dos tratamentos planejados. Como fonte móvel de potência foi utilizado um trator marca Massey Ferguson, Modelo MF 275 com 72 CV (53 kW) de potência. O experimento foi conduzido no Município de Capão Bonito do Sul, Rio Grande do Sul, em um solo de textura muito argilosa. Como objetivo geral, buscou-se responder às seguintes perguntas: (i) existe alguma diferença significativa entre a escarificação em única camada ou em mais de uma camada, considerando a força horizontal média na barra de tração, a resistência específica e o consumo horário médio de combustível como critérios, para cada nível de velocidade? ; (ii) de que forma influi o aprofundamento (espessura das camadas) na força horizontal média na barra de tração? ; e (iii) como atua o avanço (distância longitudinal entre as ponteiras das hastes), sobre a área de solo mobilizada? Foram testadas configurações com escarificação do solo em uma, duas e três camadas, com variações nas distâncias longitudinais entre as pontas das ponteiras. Os tratamentos com escarificação em duas camadas simultâneas de quinze centímetros e distância longitudinal entre as pontas das ponteiras tanto de trinta quanto de quarenta centímetros, juntamente com aquele com aprofundamento de dez e avanço de trinta centímetros apresentaram-se como mais promissores. Concluiu-se ao final deste trabalho, considerando todas as configurações testadas, que existem combinações de aprofundamento, avanço e velocidade, que revelaram-se mais eficientes que a escarificação em camada única.

Les métastases sont responsables de 90 % des décès causés par le cancer. Les métastases sont des foyers cancéreux secondaires qui se forment à distance de la tumeur d’origine. Des cellules cancéreuses quittent la tumeur primaire, rejoignent la circulation sanguine puis colonisent des organes voisins par migration à travers l’endothélium vasculaire. Ce phénomène d’adhésion à l’endothélium et de migration à travers l’endothélium appelé l’extravasation est une étape clé du processus métastatique. L’identification des molécules impliquées constitue une priorité dans le but d’élaborer de nouvelles drogues anticancéreuses. Nous avons précédemment montré que la molécule d’adhésion cellulaire InterCellular Adhesion Molecule-1 (ICAM-1) exprimée par les cellules endothéliales, est impliquée dans l’interaction des cellules de cancer de la vessie (BCs) avec l’endothélium. Cependant les ligands d’ICAM-1 n’ont pas été étudiés. Dans cette étude, nous utilisons des tests d'adhésion cellulaire et la microscopie à force atomique (AFM) afin d’identifier les ligands d’ICAM-1 et de mesurer les forces impliquées dans l’interaction ligand-ICAM-1. Nous avons identifié que les protéines MUC1 et CD43 exprimées par les BCs les plus invasives se lient à ICAM-1 en développant des forces d’intensité différente selon le couple considéré. Une analyse détaillée des événements de rupture suggère que CD43 est fortement lié au cytosquelette et que son interaction avec ICAM-1 correspond principalement à des sauts brusques. Au contraire, MUC1 semble être lié faiblement au cytosquelette et ses interactions avec ICAM-1 sont principalement associées à la formation de filaments membranaires ou « tethers ». Les forces mises en jeu lors de la migration des cellules cancéreuses à travers l'endothélium ont été étudiées par microscopie de forces de traction (TFM). Les résultats préliminaires montrent que les tractions exercées par les cellules cancéreuses lors de l’extravasation sont mesurables par TFM. / Cancer metastasis is associated with 90% cancer-associated deaths, when cancer cells escape from the primary tumor and form metastatic colonies in secondary sites. Extravasation is an important step in cancer metastasis, where cancer cells carried in blood, adhere and transmigrate through the endothelium. Therefore identifying the key molecules involved during the adhesion process could enable to develop new anticancer cancer drugs able to inhibit the adhesion of cancer cells to the endothelium. We have previously shown that InterCellular Adhesion Molecule-1 (ICAM-1) expressed by endothelial cells is involved in the interactions of bladder cancer cells (BCs) with the endothelium. However the ICAM-1 ligands have never been investigated. In this study, we combined adhesion assays and Atomic Force Microscopy (AFM) to identify the ligands involved and to quantify the forces relevant in such interactions. We report the expression of MUC1 and CD43 on BCs and demonstrate that these ligands interact with ICAM-1 to mediate cancer cell-endothelial cell adhesion in the case of the more invasive BCs. AFM experiments were performed to quantify the force ranges involved by MUC1 and CD43 during their interaction with ICAM-1. AFM measurements combined with a Gaussian Mixture Model showed distinct force ranges for the interaction of ICAM-1 with MUC1 and ICAM-1 with CD43. Furthermore, a detailed analysis of the rupture events suggests that CD43 is strongly connected to the cytoskeleton and that its interaction with ICAM-1 mainly corresponds to force ramps followed by sudden jumps. On the contrary, MUC1 seems to be weakly connected to the cytoskeleton as its interactions with ICAM-1 are mainly associated with the formation of tethers. The forces involved during the transmigration of cancer cells through the endothelium was investigated using Traction Force Microscopy (TFM). Preliminary results showed that tractions exerted by cancer cells during transmigration can be studied and quantified using TFM.

No description available.

O presente trabalho trata do estudo, análise, construção e teste de uma nova configuração para um atuador planar. O dispositivo, que apresenta uma movimentação sobre o plano com dois graus de liberdade a partir de um único dispositivo de tração, é formado por um carro, também chamado de primário, que apresenta dois enrolamentos trifásicos independentes, ortogonais entre si, montados em um núcleo ranhurado de material compósito magneticamente macio de grão isolado; e por um estator, também chamado de secundário, formado por uma chapa de alumínio plana montada sobre um núcleo ferromagnético igualmente plano, formando a área de trabalho ou de movimentação do primário. Através de um acionamento trifásico, os enrolamentos produzem campos magnéticos viajantes, fazendo com que correntes elétricas induzidas apareçam nos materiais eletricamente condutores do secundário. A interação entre os campos magnéticos e as correntes induzidas proporciona o aparecimento de uma força planar de propulsão na direção do campo magnético viajante, responsável pelo deslocamento do primário sobre a área de trabalho, definida pelo secundário. O atuador apresenta uma distribuição espacial da densidade de fluxo magnético em toda a sua estrutura. Este trabalho preocupa-se em analisar analítica, numérica e experimentalmente os fenômenos eletromagnéticos envolvidos, tanto em regime estático como dinâmico. O emprego de duas configurações para o secundário, utilizados separadamente, é investigado: no caso 1 é montado um núcleo de material ferromagnético sobre o qual é colocada uma chapa de alumínio; já no caso 2, é retirado o alumínio do conjunto, mantendo-se o mesmo material ferromagnético, a saber, aço maciço 1020. Uma análise estática e dinâmica, a partir do método dos elementos finitos tornou possível a verificação da densidade de fluxo magnético no entreferro e da distribuição da densidade de corrente elétrica induzidas nos materiais do secundário em função da excitação trifásica dos enrolamentos do primário, bem como a obtenção dos seus efeitos sobre a força planar de propulsão, considerando as duas configurações propostas para o estator. Além disso, pode-se comparar esses resultados, direta ou indiretamente, como os resultados analíticos e experimentais obtidos. Esses resultados apontam que existem diferenças significativas na utilização das duas configurações, indicando que o caso 1, quando utilizado de maneira adequada no sistema, produz uma melhor resposta de força em função da excitação elétrica. / The present work presents the study, analysis, implementation and test of a new type of planar actuator, the induction planar actuator with orthogonal windings. The device, which presents movement over the plan with two degrees of freedom from a unique traction device, is formed by a car, also called primary, which presents two three-phase independent winding, orthogonal among each other, assembled on a slotted core made of grain insulated soft magnetic composite material and by a stator, also called secondary, formed by an aluminum plate assembled over a plan ferromagnetic core equally plan, forming a work area or of primary movement. Through the three-phase operation drive, the windings produce traveling magnetic fields, having the electric induced current to appear at the electrically conductor materials of the secondary. The interaction between the magnetic fields and the induced currents provides the appearance of a planar traction force towards the traveling magnetic field, responsible for the displacement of the primary over the work area, defined by the secondary. The actuator presents magnetic flow density spatial distribution in all its structure. This paper is concerned about analyzing analytically, numerically and experimentally the phenomena involved as in steady as dynamic state. The employment of two settings to the secondary used separately is argued: in case 1 a ferromagnetic core is assembled over which is placed an aluminum plate; in case 2 the aluminum is taken off the setting, maintaining the same ferromagnetic material (steel 1020). Dynamic and statics analysis, from the finite elements method, made the verification of the magnetic flux density possible in the air gap and the distribution of the electric current density induced on the material of the secondary due to the three-phase excitation of the winding of the primary, as well as the obtainment of its effects over the planar traction force, regarding the two settings proposed for the stator. Besides, it’s possible to compare these results, direct or indirectly as analytical and experimental results obtained. These results point the there are meaningful differences at both settings, indicating that case 1, when used adequately in the system, produces better force response due to the electric excitation.