Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is now a well established analytical technique used to sample solid materials and determine their elemental composition. Two areas that are becoming increasingly important, and for which LA-ICP-MS is a key tool, are bio-imaging and the analysis of micro-particulates. However, current instrumental designs limit the practicality of the technique for these applications. This study investigates the development of a high speed, high efficiency LA-ICP-MS interface through modelling of the flow dynamics of a newly designed laser ablation cell and experimental investigation of single laser pulse response. Through this work the Sniffer-Dual Concentric Injector interface was realised. This interface reduced particle residence times within the laser cell and transport tubing. The interface was also used to investigate turbulence related aerosol dispersion within the ICP and potential designs to overcome this. The resulting design yields an interface with improved sensitivity and reduced aerosol dispersion such that a lower limit of detection is achieved, important when considering the mass of analyte in a single cell or micro-particulate, compared to existing designs. Thus the interface can be used to improve image spatial resolution as the ablation spot size, and thus pixel information, can be reduced; and also reduces total analysis time. The calibration technique Laser Ablation of a Sample In Liquid (LASIL) was also investigated as a means of calibration for solid samples. The investigation lead to the development of LASIL in a droplet, a technique that can be used to calibrate solid samples when a matrix matched standard is unavailable. The mechanism of the technique resulted in an improved laser-energy sample coupling efficiency and a reduction in the liquid to ablated mass ratio, thus decreasing sampling time. As the technique captures the ablated particulate in solution, post chemistry techniques can be used to remove analyte interferences.

Made available in DSpace on 2014-12-17T15:43:54Z (GMT). No. of bitstreams: 1 DiegoMS_DISSERT.pdf: 1792102 bytes, checksum: 305ff686e7a1606e27026b528fd1d091 (MD5) Previous issue date: 2013-01-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Low level laser irradiation (LLLI) has been used in Dentistry to promote wound healing and tissue regeneration. The literature shows a positive effect of LLLI on cell proliferation, but little is known about their effectiveness in promoting stem cells proliferation. The aim of this study was to evaluate the effect of LLLI on the proliferative rate of human periodontal ligament stem cells. Extracts of periodontal ligament were isolated from two third molars removed by surgical and/or orthodontic indication. After enzymatic digestion, the cells were grown in α-MEM culture medium supplemented with antibiotics and 15% fetal bovine serum. On the third subculture, the cells were irradiated with a InGaAlP-diode laser, using two different energy densities (0,5J/cm 2 - 16 seconds and 1,0J/cm? - 33 seconds), with wavelength of 660nm and output power of 30mW. A new irradiation, using the same parameters, was performed 48h after the first. A control group (non irradiated) was kept under the same experimental culture conditions. The Trypan blue exclusion test and the mitochondrial activity of the cells measured by MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] essay were performed to assess the cell proliferation in the intervals of 0, 24, 48 e 72 h after irradiation. The data of cell counts were submitted to nonparametrical statistical tests (Kruskal-Wallis and Mann-Whitney), considering a confidence interval of 95%. DAPI (4 -6-Diamidino-2-phenylindole) staining of the cells was performed at 72h interval to evaluate possible nuclear morphological changes induced by LLLI. The results of this study show that the energy density of 1,0 J/cm? promoted greater cell proliferation compared to the other groups (control and 0,5 J/cm?) at intervals of 48 and 72h. The mitochondrial activity measured by MTT essay showed similar results to the Trypan blue cell counting test. The group irradiated with 1,0J/cm? exhibited a significantly higher MTT activity in the intervals of 48 and 72h, when compared to the group irradiated with 0,5J/cm?. No nuclear morphological change was observed in the cells from the three groups studied. It is concluded that LLLI has stimulatory effects on the proliferation of human periodontal ligament stem cells. Therefore, the use of laser irradiation in this cell type may be important to promote future advances in periodontal regeneration / O laser de baixa intensidade (LBI) tem sido utilizado na Odontologia com a finalidade de promover cicatriza??o e regenera??o dos tecidos. A literatura mostra um efeito positivo do LBI na prolifera??o celular, por?m pouco se sabe sobre a sua efic?cia na prolifera??o de c?lulas-tronco. O objetivo deste estudo foi avaliar o efeito da irradia??o do LBI na taxa proliferativa de c?lulas -tronco do ligamento periodontal humano. Extratos de ligamento periodontal foram isolados de dois terceiros molares h?gidos removidos por indica? ?o cir?rgica e/ou ortod?ntica. Ap?s a digest?o enzim?tica, as c?lulas foram cultivadas em meio de cultura α-MEM suplementado com antibi?ticos e 15% de soro fetal bovino. No terceiro subcultivo, as c?lulas foram irradiadas com um laser diodo InGaAlP, utilizando-se duas diferentes densidades de energia (0,5J/cm 2 - 16 segundos e 1,0J/cm? - 33 segundos), comprimento de onda de 660nm e pot?ncia de 30mW. Uma nova irradia??o, utilizando os mesmos par?metros, foi realizada 48 h ap?s a primeira. Um grupo controle (n?o irradiado) foi mantido nas mesmas condi??es experimentais de cultivo. O m?todo de exclus?o por azul de Tripan e a atividade mitocondrial das c?lulas medida atrav?s do ensaio de MTT [brometo de 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetraz?lio], nos intervalos de 0, 24, 48 e 72 h p?s-irradia??o, foram utilizados a fim de avaliar a prolifera??o celular. Os dados das contagens celulares foram submetidos a testes estat?sticos n?o param?tricos de Kruskal-Wallis e Mann-Whitney, considerando um intervalo de confian?a de 95%. Com o objetivo de verificar poss?veis altera??es morfol?gicas nucleares induzidas pelo laser, as c?lulas foram submetidas ? marca??o com DAPI (4 -6-Diamidino-2-phenylindole) no intervalo de 72 h. Os resultados do presente estudo mostraram que a densidade de energia de 1,0 J/cm? promoveu maior prolifera??o das c?lulas em compara??o com os outros grupos (controle e laser 0,5 J/cm?) nos intervalos de 48 e 72 h. A atividade mitocondrial, medida pelo ensaio de MTT, apresentou resultados semelhantes ?s contagem celulares com azul de Tripan, com o grupo irradiado com 1,0 J/cm? exibindo uma atividade significativamente maior do MTT nos intervalos de 48 e 72 h, quando comparado com o grupo irradiado com 0,5 J/cm?. Nenhuma altera??o morfol?gica nuclear foi observada, tanto das c?lulas do grupo controle quanto nas c?lulas irradiadas. Conclui-se que o LBI apresenta efeitos estimulantes sobre a prolifera??o de c?lulas-tronco do ligamento periodontal humano. Portanto, a aplica??o da laserterapia neste tipo celular pode ser importante para futuros avan?os na regenera??o periodontal

During embryogenesis and post-embryonic patterning, active transport of the phytohormone auxin, reflected in the expression of the Arabidopsis PIN family of auxin efflux mediators, generates local auxin distributions that are crucial for correct organ and tissue specification. Polar auxin transport routes have also long been postulated to regulate vein formation in the leaf. The molecular identification of PIN proteins has made it possible to investigate this hypothesis further by visualizing auxin transport routes in developing leaves. In Arabidopsis leaf primordia, PIN1 is expressed before the earliest known markers of vascular identity, in domains that are gradually restricted to sites of vein formation. PIN1 polarity indicates that auxin is directed towards distinct “convergence points” (CPs) in the marginal epidermis, from which it defines the sites of major vein formation. Within incipient veins, PIN1 polarity indicates drainage of auxin into preexisting veins, such that veins connected at both ends display two divergent polarities. Local auxin application triggers the formation of ectopic CPs and new veins, demonstrating the sufficiency of auxin as a vein-specifying signal. However, not all PIN1-labeled auxin transport routes differentiate as veins: Minor veins are initially unstable, suggesting local competition for auxin transport. Expression of ATHB8, a marker of vascular cell selection, correlates with enhanced PIN1 expression domain (PED) stability and vascular differentiation. Auxin application and auxin transport inhibition reveal that both CP formation in the epidermis and subepidermal PED dynamics are auxin-dependent and self-organizing. Furthermore, normal auxin perception through the ARF-Aux/IAA signaling pathway is required for the restriction of PIN1-mediated auxin transport to narrow subepidermal domains. ARF-Aux/IAA signaling is known to control auxin transport through the regulation of PIN1 dynamics, but the mechanism of this regulation is unclear. It is here shown that two redundantly acting AUXIN RESPONSE FACTOR (ARF) transcription factors, ARF5/MONOPTEROS (MP) and ARF7/NPH4, jointly regulate both PIN1 expression and localization during lateral root patterning in Arabidopsis, in part through the direct transcriptional activation of PIN1 by MP. Taken together, these results indicate that feedback between PIN-mediated auxin transport and ARF-Aux/IAA signaling regulates the patterning of root and shoot organs.

During embryogenesis and post-embryonic patterning, active transport of the phytohormone auxin, reflected in the expression of the Arabidopsis PIN family of auxin efflux mediators, generates local auxin distributions that are crucial for correct organ and tissue specification. Polar auxin transport routes have also long been postulated to regulate vein formation in the leaf. The molecular identification of PIN proteins has made it possible to investigate this hypothesis further by visualizing auxin transport routes in developing leaves. In Arabidopsis leaf primordia, PIN1 is expressed before the earliest known markers of vascular identity, in domains that are gradually restricted to sites of vein formation. PIN1 polarity indicates that auxin is directed towards distinct “convergence points” (CPs) in the marginal epidermis, from which it defines the sites of major vein formation. Within incipient veins, PIN1 polarity indicates drainage of auxin into preexisting veins, such that veins connected at both ends display two divergent polarities. Local auxin application triggers the formation of ectopic CPs and new veins, demonstrating the sufficiency of auxin as a vein-specifying signal. However, not all PIN1-labeled auxin transport routes differentiate as veins: Minor veins are initially unstable, suggesting local competition for auxin transport. Expression of ATHB8, a marker of vascular cell selection, correlates with enhanced PIN1 expression domain (PED) stability and vascular differentiation. Auxin application and auxin transport inhibition reveal that both CP formation in the epidermis and subepidermal PED dynamics are auxin-dependent and self-organizing. Furthermore, normal auxin perception through the ARF-Aux/IAA signaling pathway is required for the restriction of PIN1-mediated auxin transport to narrow subepidermal domains. ARF-Aux/IAA signaling is known to control auxin transport through the regulation of PIN1 dynamics, but the mechanism of this regulation is unclear. It is here shown that two redundantly acting AUXIN RESPONSE FACTOR (ARF) transcription factors, ARF5/MONOPTEROS (MP) and ARF7/NPH4, jointly regulate both PIN1 expression and localization during lateral root patterning in Arabidopsis, in part through the direct transcriptional activation of PIN1 by MP. Taken together, these results indicate that feedback between PIN-mediated auxin transport and ARF-Aux/IAA signaling regulates the patterning of root and shoot organs.