Accidents cause economic losses to the company as well as suffering and general discontent among the employees. With an increased global responsibility, companies are not only answerable for what goes on inside their own gates but also for retailers and customers. When the packaging becomes a danger, how will we know what to replace it with? At IMI Hydronic Engineering, employees hurt themselves on the metal staples that seal the cartons, but is replacing metal staples with plastic tape an economical and safely viable option? This thesis dives into the workplace environment and collects data from semi-structural interviews with the employees and an evaluation of internal accident records. The main focuses are safety and economics, although the economy aspect has had to stand back due to the lack of empirical data. The results show that the tools and systems in place to protect the employees, where applied, are working and the workers believe that their job could be executed with a lower risk, perhaps even without a loss of production. The suggestion to the company is that to fully understand the costs, a collection of data regarding the current costs is needed and that usage of gloves by the employees might help lower the number of accidents per year. Suggestions for further studies include ecological aspects, profit versus costs and product returns due to inadequate packaging.

Les travaux présentés dans ce manuscrit sont relatifs à la conception et au développement d’antennes basées sur les structures artificielles – métamatériaux. La première antenne conçue et réalisée est une antenne bi-fonction en bande L (~1GHz) (GPS et DME) à diversité de bande/de polarisation, destinée aux applications aéronautiques. Ces travaux rentrent dans le cadre du projet MSIE (pôle de compétitivité ASTHEC) pour lequel notre LEME a été très actif. Les partenaires industriels de ce projet sont EADS/IW, Dassault aviation, INEO-Défense, SATIMO. Les résultats montrent la faisabilité d’une antenne unique pouvant avoir simultanément deux fonctions avec une diversité de polarisation et de bande spectrale. L’utilisation des métamatériaux a permis en particulier le maintien de la polarisation circulaire de l’antenne GPS -L1 à L5. La fonction DME a été consolidée avec le maintien de son gain. La seconde antenne est une antenne cavité Fabry-Pérot mettant en œuvre une structure partiellement réfléchissante double couche. Nous avons démontré le phénomène physique d’inversion de la phase du coefficient de réflexion de la PRS. Nous avons obtenu un gradient positif de phase sur une bande de 5 GHz autour de 80GHz. Grace à ce profil nouveau de la phase obtenu par la structure métamatériau PRS, on dispose d’une avance linéaire de la phase qui compense le retard du à la cavité Fabry-Pérot. Ainsi on maintient les conditions de résonance de la cavité sur une large bande, 5GHz. Nous démontrons, que la mise en œuvre de cette structure aux caractéristiques inédites permet de réaliser une antenne cavité ultra-directive sur une très large bande spectrale de 5GHz. Les performances atteintes sont une directivité de 35 à 40dBi sur 5 GHz, une adaptation parfaite (gain ~ directivité) avec très peu de sources primaires. L’antenne est compacte avec une hauteur totale inférieure au 10mm (connecteur compris) et une surface de 100mmx100mm. / The work presented in this manuscript is related to the design and development of antennas based on artificial structures - metamaterials. The first designed and built antenna is a GPS and DME dual-function in the L (~ 1GHz). It is an antenna designed with polarization and spectral diversities for aeronautical applications. The work is within the MSIE project of ASTHEC cluster for which our laboratory (LEME) was very active. The industrial partners of the project are EADS/IW, Dassault Aviation, INEO-Defense SATIMO. The results show the feasibility of a single antenna having simultaneously two functions with a diversity of polarization and spectral band. The use of metamaterials enabled in particular the preservation of circular polarization of the GPS antenna on the bands ranging from L1 to L2. The DME function was consolidated with the same gain.The second antenna is an antenna Fabry-Perot cavity employing a partially reflective structure (PRS) Double-layer. We have demonstrated by numerical simulation and experimental characterization, the physical phenomenon of inversion phase of the reflection coefficient PRS. We obtain a positive gradient of the phase over a broad band of 5 GHz around 80GHz. Thanks to this new profile obtained by the PRS metamaterial structure, it has a linear advance of the phase which compensates for the delay of the Fabry-Perot cavity. Thus the cavity resonance conditions are maintained over a wide band, 5GHz. We demonstrate that the implementation of this structure with unique features allows a highly directive antenna cavity over a very wide spectral band 5GHz. The performance are a directivity of 35-40 dBi over 5 GHz, a perfect adaptation (gain ~ directivity) with very few primary sources.

La fabrication de cellules de piles à combustible IT-SOFC de large dimension par un nouveau procédé simple et peu coûteux est présentée dans ce manuscrit. L’optimisation de ce nouveau procédé en regard de l’utilisation d’agents de porosité, d’épaisseur de couches et de température de frittage a été réalisée. Les résultats des tests électrochimiques sur des cellules de surface active 10 cm2 réalisés dans le dispositif Fiaxell semi-ouvert ont été détaillés pour différentes cellules. Des tests de performance de longue durée ont également été menés sur le dispositif Fiaxell, présentés et discutés. La préparation et la réalisation d’un nouveau banc de test de stack a également été mené et présenté dans ces travaux. / The fabrications of large area IT-SOFC planar cell by new simple and cost effective process were explained. The optimization of the new process with respect to pore formers, thickness of layers, sintering temperature were performed. The electrochemical results of 10cm2 performed in Fiaxell open flange set up were detailed with respect to different configuration. Long term ageing performance tests of single cells were conducted in Fiaxell device and results are discussed. Preparation of new test bench and stacking process performed till now were briefed.

This research comprises an experimental and theoretical study on convective boiling inside tubes containing twisted-tape inserts. The demand for more compact and efficient thermal systems, in which the heat exchangers plays an important role, has led to the development and use of various heat transfer enhancement techniques. Among them twisted-tape insert as a swirl flow device is one of the most used. Twisted-tape inserts have been used for over more than one century ago as a technique of heat transfer enhancement applied to heat exchangers. However, the heat transfer augmentation comes together with pressure drop increment, impacting the pumping power and, consequently, the system efficiency. Moreover, until now it is not clear, the operational conditions under which the heat transfer coefficient augmentation by the use of twisted-tape inserts overcomes pressure drop penalty. In the present study, initially, extensive investigations of the literature concerning convective boiling inside plain tubes with and without twisted-tape inserts were performed. This literature review covers pressure drop, heat transfer coefficient and the leading frictional pressure drop gradient and heat transfer coefficient predictive methods during convective boiling inside tubes with and without twisted-tape inserts. Then, pressure drop and heat transfer coefficient results acquired in the present study were obtained in an experimental apparatus of 12.7 and 15.9 mm ID tubes during flow boiling of R134a for twisted-tape ratios of 3, 4, 9, 14 and tubes without inserts, mass velocities ranging from 75 to 200 kg/m2 s, saturation temperatures of 5 and 15°C and heat fluxes of 5 and 10 kW/m2. The experimental results were parametrically analyzed and compared against the predictive methods from literature. An analysis of the enhancement of the heat transfer coefficient and the pressure drop penalty is presented. Heat transfer coefficient increments up to 45% keeping the same pumping power and pressure drop penalty of about 35% were obtained by using twisted-tape relative to tubes without inserts. Additionally, through comparison of the present study experimental results with the predictive methods from the literature for heat transfer coefficient during two-phase flow inside tube containing twisted-tape inserts, it was verified that non of these methods predict satisfactory well the experimental results. However, a new method was develop for predicting the heat transfer coefficient during flow boiling inside tubes containing twisted-tape inserts based on the experimental results obtained in the present study. The predictive method takes into account the physical picture of the swirl flow phenomenon by including swirl flow effects promoted by the twisted-tape inserts. The proposed method predicts satisfactorily well the data obtained in the present study, predicting 89.1% of the experimental data within an error band of ± 30% and absolute mean deviation of 15.7%. / A presente pesquisa trata-se de um estudo teórico e experimental sobre a ebulição convectiva no interior de tubos com fitas retorcidas. A crescente demanda por sistemas térmicos mais compactos e eficientes, nos quais os trocadores de calor apresentam elevada relevância, tem motivado o desenvolvimento de inúmeras técnicas de intensificação de troca de calor, sendo que a utilização de fitas retorcidas é uma das técnicas mais adotadas. Fitas retorcidas são utilizadas como técnicas de intensificação de troca de calor há mais de um século. Entretanto o incremento da transferência de calor é acompanhado do aumento da perda de pressão, que por sua vez implica em aumento da potência de bombeamento, e consequentemente afeta a eficiência global do sistema. Adicionalmente, até os dias de hoje não há consenso sobre as condições operacionais em que o ganho com o incremento do coeficiente de transferência de calor é superior à perda devido ao aumento da perda de pressão. Neste estudo, inicialmente foi realizada uma extensa revisão da literatura sobre a ebulição convectiva no interior de tubos com e sem fitas retorcidas. Esta revisão aborda aspectos relacionados à perda de pressão e ao coeficiente de transferência de calor, juntamente com os métodos de previsão destes parâmetros. Foram realizados experimentos para determinação experimental de perda de pressão e coeficiente de transferência de calor, em aparato experimental contando com tubos horizontais com diâmetros internos iguais a 12,7 e 15,9 mm, para escoamento bifásico de R134a, razões de retorcimento iguais a 3, 4, 9, 14 e tubo sem fita, velocidades mássicas entre 75 e 200 kg/m²s, temperaturas de saturação iguais a 5 e 15°C, e fluxo de calor iguais a 5 e 10 kW/m². Os resultados experimentais foram analisados e comparados com estimativas segundo métodos disponíveis na literatura. Uma análise do aumento do coeficiente de transferência de calor e da perda de pressão friccional é apresentada. Foram verificados incrementos do coeficiente de transferência de calor de até 45% para a mesma potência de bombeamento, e aumento de perda de pressão de aproximadamente 35% para tubos com fitas retorcidas em relação aos tubos sem fita. Adicionalmente, através da comparação dos resultados experimentais com os métodos de previsão para coeficiente de transferência de calor, foi verificado que nenhuma metodologia apresentava previsões satisfatórias dos resultados. Portanto um novo método para previsão do coeficiente de transferência de calor durante ebulição convectiva no interior de tubos com fitas retorcidas foi desenvolvido com base nos resultados experimentais obtidos durante o presente estudo. O método proposto é função de parâmetros geométricos e do escoamento, e também de parâmetros físicos do escoamento rotacional induzido pela fita. A metodologia desenvolvida apresenta previsões satisfatórias dos resultados experimentais, prevendo 89,1% dos resultados experimentais com erro inferior a ± 30% e erro médio absoluto igual a 15,7%.

Made available in DSpace on 2016-04-28T18:23:08Z (GMT). No. of bitstreams: 1 Felipe Augusto de Souza Santos.pdf: 1601405 bytes, checksum: 5aceb79107bef912ae3c37583b50be9c (MD5) Previous issue date: 2015-09-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This research aims to investigate issues of theatrical aesthetics and the process of creation of Samuel Beckett, from a study on aspects of his work as a playwright and director of his own plays. First it will be made an approach about the relationship between text and scene in Beckett s work, that is, we will make a survey of the major aesthetic and structural features of plays such as Waiting for Godot, Endgame, Happy days and Footfalls, in order to problematize some of major issues involving the dramaturgy of Beckett, and also a study of the trajectory of Beckett from playwright to director. Later, we will make an analysis of the dramaturgical text of Krapp s last tape, using concepts from the writings of Mikhail Bakhtin and the Circle, such as dialogism, polyphony and chronotope, and also a reflection on the various performances of Krapp s last tape directed by Beckett. For this, we will use an unpublished translation of Krapp s last tape held by the researcher and published in this work as well as Beckett s directing notebook, with notes of the staging process of his version of Krapp s last tape performed at the Schiller-Theater in Berlin in 1969, and the changes undergone by the dramatic text. The results suggest the importance of the staging process performed by Beckett on some of his major plays, particularly Krapp s last tape, as a revising and defining element of his dramaturgy / Esta pesquisa tem como objetivo investigar questões ligadas à estética teatral e ao processo de criação de Samuel Beckett, a partir de um estudo relativo a aspectos de seu trabalho como dramaturgo e encenador de suas próprias peças. Primeiramente será realizada uma abordagem acerca da relação entre texto e cena na obra de Beckett, ou seja, faremos um levantamento das principais características estéticas e estruturais de peças como Esperando Godot, Fim de partida, Dias felizes e Passos, no intuito de problematizarmos algumas das principais questões envolvendo a dramaturgia de Beckett, e também um estudo acerca da trajetória de Beckett de dramaturgo a encenador. Posteriormente, faremos uma análise do texto dramatúrgico de A última gravação de Krapp, utilizando conceitos provenientes dos escritos de Mikhail Bakhtin e do Círculo, tais como dialogismo, polifonia e cronotopo, e também uma reflexão sobre as diversas encenações de A última gravação de Krapp dirigidas por Beckett. Para tanto, serão utilizados uma tradução inédita de A última gravação de Krapp realizada pelo pesquisador e publicada neste trabalho, bem como o caderno de direção de Beckett, contendo as anotações do processo de encenação de sua montagem de A última gravação de Krapp no Schiller-Theater de Berlim, em 1969, e as alterações sofridas pelo texto dramatúrgico. Os resultados obtidos apontam para a importância do processo de encenação realizado por Beckett em relação a algumas de suas principais peças, em especial A última gravação de Krapp, como elemento revisor e definidor de sua dramaturgia

Skin, more specifically the outermost skin layer, the stratum corneum (SC), forms an extremely effective barrier, preventing both the loss of heat and water, and the ingress of micro-organisms and chemicals. Assessing the rate and extent of drug permeation into or through the skin is important both to evaluate the usefulness of a drug for topical or transdermal delivery, and to compare different formulations to assess their bioequivalence. Prediction of drug permeation is logistically, ethically and economically preferable to in vivo measurements. The recent progress that has been made with empirical and mechanistic mathematical models, along with in vitro diffusion cell techniques has been reviewed. However, currently, in vivo measurements, in man, are still required. For new chemical entities, the need for clinical trials is clear. In the case of generic products, however, there is considerable effort currently being expended to replace expensive, subjective clinical trials with objective, validated measurements of drug permeation, in vivo, in particular to assess bioequivalence. The tape stripping technique has emerged as a promising technique to objectively measure drug permeation through skin, and is the focus of this thesis. After formulation application and removal, layers of SC are sequentially removed by adhesive tapes. As the SC performs the main barrier function of the skin, measuring the rate and extent of drug permeation through this layer is assumed to be related to overall topical bioavailability. The work in this thesis concentrates on performing tape stripping studies such that all tapes are analysed individually, and drug concentration as a function of SC depth is measured. The concentration depth profiles across the SC may be fitted to an appropriate solution of Fick's second law of diffusion to obtain estimates of the vehicle-SC partition coefficient and the drug's diffusivity in the membrane. These dermato-pharmacokinetic parameters may be compared for different formulations.

Atopic eczema is an incurable disorder of the skin. Sufferers are afflicted with hypersensitivity to environmental agents such as soaps (detergents), animal dander, pollen, specific foods and sometimes even water. Genetic mutations in atopic eczema compromise the development of the stratum corneum resulting in xerotic skin that is prone to cracking and increased permeability which leads to irritation due to the influx of exogenous material through the skin. The causes of atopic eczema are due to a combination of genetic and environmental factors and it is, therefore, a difficult disease to manage. Emollients and topical corticosteroids are the mainstay treatments for eczema. However, they do not treat the underlying cause of the flare-ups frequently seen in the condition; the damaged skin barrier. Defects in the skin barrier arise from premature desquamation of the stratum corneum. The main contributors to barrier breakdown are the up-regulation of skin proteases that are located in the skin. Since zinc is a known protease inhibitor, it would thus follow that a topical treatment for skin barrier repair should be developed. Therefore, the main objectives of this thesis are to successfully incorporate zinc into a formulation to develop a novel class of treatment for eczema and to assess the delivery of the element into the skin. In this thesis, methods to assess and characterise changes to skin barrier function and to extract and quantify zinc in the stratum corneum have been established. The development of two novel topically applied formulations containing zinc lactate as the active ingredient (1% w/w zinc lactate cream and a 2% w/v zinc lactate formulation) has been achieved and the uptake of zinc from the preparations in vitro determined. Further, the in vitro percutaneous penetration of zinc from three commercially available preparations has been investigated and compared to that recovered from the stratum corneum after passive diffusion with the novel zinc formulations. Additionally, in vivo uptake of zinc into human stratum corneum from Sudocremis ® reported. Scanning electron microscopy has revealed the distribution of zinc on the surface of skin treated with various formulations and has also allowed the efficiency of two cleaning procedures to be ascertained. The delivery of zinc from the novel topical formulation; 1% w/w zinc lactate cream, was more efficient than that the three commercial formulations and shows promise as a new approach to treat atopic eczema.

Cost effective high volume manufacture of solid oxide fuel cells (SOFCs) is a major challenge for commercial success of these devices. More than fifteen processing methods have been reported in the literature, many of which could be used in various combinations to create the desired product characteristics. For some of these processes, high volume manufacturing experience is very limited or non-existent making traditional costing approaches inappropriate. Additionally, currently available cost models are limited by a lack of incorporation of device performance requirements. Therefore, additional modeling tools are needed to aid in the selection of the appropriate processing techniques prior to making expensive investment decisions. This project describes the development of a SOFC device performance model and a manufacturing process tolerance model. These models are then linked to a preliminary cost model; creating a true multi-process, performance based cost model that permits the comparison of manufacturing cost for different combinations of three processing methods. The three processing methods that are investigated are tape casting, screen printing, and sputtering. . This model is capable of considering production volume, process tolerance and process yield, in addition to the materials and process details. Initial comparisons were performed against processes used extensively within the solid oxide fuel cell industry and the cost results show good agreement with this experience base. Sensitivity of manufacturing costs to SOFC performance requirements such as maximum power density and operation temperature are also investigated.

Abstract This thesis describes a detailed investigation of new glass 10Li₂O−10Na₂O−20K₂O−60MoO₃ (LNKM), ceramic (α-MoO₃) and ceramic-commercial glass (PZ29-GO17, rutile TiO₂-GO17) composites to satisfy the future requirements for ultra-low fabrication temperature materials and their associated processes. The initial part of the thesis is devoted to the development of the LNKM glass by a glass-melting and quenching process, followed by an investigation into its structural, microstructural and microwave dielectric properties. The prepared glass had ultra-low glass transition and melting temperatures of 198 and 350 °C, respectively. The glass pellet heat-treated at 300 °C had a relative permittivity (εr) of 4.85 and a dielectric loss (tan δ) of 0.0009 at 9.9 GHz. The temperature dependence of the relative permittivity was (τε) 291 ppm/°C. Another part of the work concerns α-MoO₃ ceramic, its preparation by uniaxial pressing and sintering at 650 °C followed by an investigation of its structural, microstructural, thermal and microwave dielectric properties. It had an εr of 6.6, tan δ of 0.00013 (at 9.9 GHz) and τε of 140 ppm/°C. In addition to this, a functional ultra-low temperature co-fired composite was developed based on commercial PZ29 and 50 wt.% of GO17 glass followed by tape casting and co-firing with Ag at 450 °C. The average values of the piezoelectric (d₃₃) and voltage (g₃₃) coefficients were 17 pC/N and 30 mV/N, respectively. The sintered sample had an average CTE value of 6.9 ppm/°C measured in the temperature range of 100–300 °C. The εr and tan δ of the sintered substrates were 57.8 and 0.05 at 2.4 GHz, respectively. Additionally, a new ceramic-glass composite was developed using rutile TiO₂-GO17, and co-fired with Ag at 400 °C. It had an average CTE value of 8.3 ppm/°C measured in the temperature range of 100–300 °C. This composite substrate showed εr of 15.5 and tan δ 0.003, at 9.9 GHz. Moreover, it also had τε of -400 ppm/°C at 9.9 GHz measured in the temperature range of −40 to 80 °C. The findings of the thesis reveal the feasibility of the ultra-low temperature co-fired ceramic (ULTCC) technology for high-frequency telecommunication devices as well as for electronics packages. Additionally, a first step to develop functional ULTCC has been taken. / Tiivistelmä Tässä väitöskirjassa kuvataan uuden lasin 10Li₂O−10Na₂O−20K₂O−60MoO₃ (LNKM), keraamin (α-MoO₃) sekä keraami-lasi (PZ29-GO17, rutiili TiO₂-GO17) komposiittien tutkimustulokset, jotka mahdollistavat tulevaisuuden sähkökeraamisten materiaalien ja komponenttien valmistuksen ultra-matalissa valmistuslämpötiloissa. Väitöskirjan alkuosa keskittyy LNKM lasin kehitykseen lasin sulatus- ja karkaisuprosessilla, sekä tämän materiaalin mikrorakenteen sekä mikroaaltoalueen dielektristen ominaisuuksien tarkasteluun. Valmistetulla lasilla oli ultra-matala lasittumislämpötila 198 °C sekä sulamislämpötila 350 °C. Lasipelletin, joka lämpökäsiteltiin 300 °C:ssa, suhteellinen permittiivisyys (εr) oli 4,85 ja dielektriset häviöt (tan δ) 0,0009 9,9 GHz taajuudella. Suhteellisen permittiivisyyden lämpötilariippuvuus (τε) oli 291 ppm/°C. Toinen osa työtä käsittelee α-MoO₃ keraamia, josta valmistettiin näytteet mikrorakenne ja mikroaaltoalueen dielektristen ominaisuuksien tutkimuksiin aksiaalisella puristuksella ja sintraamalla 650 °C:ssa. Valmistetun materiaalin suhteellinen permittiivisyys oli 6,6, häviöt 0,00013 (9,9 GHz:ssa) ja permittiivisyyden lämpötilariippuvuus 140 ppm/°C. Näiden lisäksi kehitettiin toiminnallinen ultra-matalan lämpötilan yhteissintrattu komposiitti perustuen kaupalliseen pietsosähköiseen keraamiin (PZ29) ja lasiin (GO17). Komposiitista valmistetiin monikerrosrakenne nauhavalulla ja yhteissintraamalla hopeaelektrodien kanssa 450 °C:ssa. Keskimääräiset arvot pietsosähköiselle varausvakiolle (d₃₃) sekä jännitevakiolle (g₃₃) olivat 17 pC/N ja 30 mV/N. Sintratun näytteen keskimääräinen lämpölaajenemiskerroin oli 8,3 ppm/°C lämpötila-alueella 100–300 °C. Tämän komposiittisubstraatin suhteellinen permittiivisyys oli 15,5 ja häviötangentti 0,003 9,9 GHz:n taajuudella. Lisäksi suhteellisen permittiivisyyden lämpötilariippuvuus oli -400 ppm/°C samalla 9,9 GHz:n taajuudella, kun lämpötilan mittausalue oli −40–80 °C. Tämän väitöstyön tulokset osoittavat ultra-matalan lämpötilan yhteissintrattavan keraamiteknologian (ULTCC) soveltuvuuden korkean taajuuden tietoliikennesovelluksiin ja elektroniikan pakkausteknologiaan. Lisäksi työssä on otettu ensimmäiset askeleet funktionaalisten ULTCC materiaalien kehittämiseksi.

Introdução: o fator de proteção solar (FPS) dos filtros solares é determinado in vivo pela aplicação de uma quantidade padrão de 2mg/cm². Na prática, os usuários aplicam uma quantidade menor e de maneira irregular o que afeta o FPS final. Modelos matemáticos mostram que a reaplicação do fotoprotetor resulta em um aumento de 15-40% na capacidade de proteção à radiação ultravioleta. Objetivos: avaliar se a reaplicação de filtro solar aumenta a quantidade e melhora a regularidade do filme do produto na pele. Métodos: os voluntários selecionados foram solicitados a aplicar um filtro solar padronizado composto por benzofenona 6% (FPS 6) em ambos antebraços previamente lavados com sabonete neutro. Após 30 minutos o fotoprotetor foi reaplicado em um antebraço, selecionado previamente por computador para evitar a influência do lado dominante. Cinco fitas adesivas foram coletadas de duas diferentes áreas de cada antebraço, 30 minutos após a primeira aplicação e 30 minutos após a reaplicação. A concentração de benzofenona foi medida por cromatografia líquida de alta eficiência e a quantidade do filtro estimada por correlação matemática entre a quantidade de benzofenona removida nas fitas e a concentração na formulação. Resultados: um total de 107 voluntários, com idades entre 18 e 35 anos, foram selecionados. Entre eles, 36 participaram da parte prática do estudo (21 mulheres e 15 homens, idade média de 22,6 anos) A mediana da quantidade do filme de filtro solar aplicado à pele com 1 aplicação foi de 0,43mg/cm² (0,17-1,07) e com 2 aplicações foi de 0,95mg/cm² (0,18-1,91) e essa diferença foi considerada estatisticamente significativa (p=0,002). A variação comparando a uniformidade do filme com 1 e 2 aplicações não foi significativa (p=0,423). Conclusões: a reaplicação de filtro solar resulta em uma melhora da quantidade de produto aplicado à pele, refletindo, provavelmente, em uma melhora da proteção à radiação ultravioleta. Contudo, mesmo com a reaplicação a quantidade mediana foi inferior à preconizada (2mg/cm²) e não foi uniforme, confirmando que o fator de proteção real é muito inferior ao estabelecido no rótulo do produto. Os resultados reforçam a recomendação de reaplicar o produto para atingir um melhor nível de fotoproteção. / Background: the sun protection factor (SPF) of sunscreens is determined in vivo by the application of a standard amount of 2mg/cm², under controlled conditions. Individuals usually apply a smaller and irregular amount, compromising the final sun protection. Theoretical models show that sunscreen reapplication results in an increase of 15% to 40% in the UV protection capacity. Objective: to verify how young individuals use the filter and whether its reapplication increases the amount and regularity of the product in the skin, under real conditions. Methods: the selected volunteers were asked to apply a standardized sunscreen with 6 % benzophenone on both forearms. After 30 minutes, the sunscreen was reapplied in one of the forearms. Five tape-strips were collected from 2 different sites in each forearm, 30 minutes after the first application and 30 minutes after reapplication. The concentration of benzophenone was measured by liquid chromatography and the quantity of filter was estimated by calculating the correlation between the amount of benzophenone that was removed by the tapes, and the quantity present in the formulation. Results: A total of 107 volunteers, with ages between 18 and 35 years, were selected. Among them, 36 volunteers (21 female and 15 male, mean age 22.6 years) participated in the practical part of the study. The overall median sunscreen amount was 0,43mg/cm² (0.17–1.07) with 1 application and 0.95mg/cm² (0.18-1.91) with 2 applications, and the difference between sites was significant (p=0,002). The variation comparing the uniformity of the film with 1 and 2 applications was not significant (p=0,423). Conclusion: the reapplication of sunscreen contributes for a better amount of the product in the skin, probably reflecting in a better sun protection. However, even with reapplication, the median amount was less than the recommended one (2mg/cm²) and not homogeneous, confirming that the real level of protection is much lower than the stated SPF of the product. The results support the recommendation for reapplying filters to obtain a more reliable chemical photoprotection.