<p>Najče&scaron;ća komplikacija nakon ugradnje silikonskih implantata za dojku je kontraktura fibrozne kapsule (KK), koja se normalno stvara oko implantata u sklopu reakcije oko stranog tela. Najozbiljnija komplikacija nakon ugradnje silikonskih implantata za dojku je anaplastični krupnoćelijski limfom koji se javlja isključivo kod pacijentkinja koje imaju ugraĎene implantate (eng. Breast-implant associated anaplastic large cell lymphoma &ndash; BIA ALCL). Uzrok nastanka ovih komplikacija ostaje nepoznat. Ustanovljeno je da se KK manje javlja kod implantata koji imaju makroteksturisanu povr&scaron;inu i kod onih koji su presvučeni poliuretanskom penom. S druge strane, BIA-ALCL se če&scaron;će dijagnostikuje kod pacijentkinja kojima su ugraĎeni upravo makroteksturisani implantati. Subklinička infekcija koja predstavlja odgovor organizma na postojanje biofilma na ugraĎenim implantatima, predstavlja jedan od najznačajnijih etiolo&scaron;kih faktora za nastanak KK i BIA-ALCL. Biofilm je konglomerat mirkoorganizama uronjenih u matriks koji ih &scaron;titi od dejstva antibiotika i antiseptika. Kako je nemoguće delovati medikamentozno na eradikaciju biofilma, brojni autori daju razne preporuke u cilju izbegavanja kontaminacije implantata tokom operativnog zahvata, a time i formiranja biofilma. Pored brojnih mera, savetuje se i ispiranje džepa u koji će se plasirati proteza kao i same proteze, nekim od antiseptičkih ili antibiotskih rastvora. Do sada ne postoje prihvaćene jasne preporuke o načinu ispiranja različitih implantata, objavljena su samo lična iskustva raznih autora. Ciljevi ovog istraživanja su bili da se ustanovi mogućnost formiranja biofilma četiri različite bakterije (Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa i Ralstonia pickettii) na tri različito teksturisana silikonska implantata za dojku (sa porama veličine 70-150 &mu;m, 50&ndash;900 &mu;m i 13 &mu;m) u in vitro uslovima; da se ispita da li ispiranje antisepticima (oktenidindihidrohloridom i povidon jodom), ili antibiotikom (cefuroksimom) ili istovremeno me&scaron;avinom povidon joda i antibiotika pre bakterijske kontaminacije sa četiri različite bakterije ima uticaja na formiranje biofilma na tri različito teksturisana implantata za dojke u in vitro uslovima; i da se ispita efekat antiseptika u odnosu na efekat antibiotika na formiranje bakterijskog biofilma na tri različito teksturisana silikonska implantata za dojku. Istraživanje je koncipirano kao prospektivna studija u vidu eksperimenta koji je izveden u Laboratoriji za mikrobiologiju, Instituta za javno zdravlje Vojvodine u Novom Sadu. Za izvoĎenje eksperimenta kori&scaron;ćeni su uzorci tri vrste silikonskih implantata za dojku sa različito teksturisanom povr&scaron;inom, odnosno porama različite veličine: 70-150 &mu;m, 50&ndash;900 &mu;m, i 13 &mu;m. Od svakog od navedenih implantata su pravljeni uzorci, sečenjem kapsula implantata na komadiće veličine 1x1 cm. Ukupno je bilo 1440 uzoraka. Na osnovu teksture uzorci su podeljeni u tri grupe: Grupa 1 (pore veličine 70-150 &mu;m), Grupa 2 (pore veličine 50&ndash;900 &mu;m) i Grupa 3 (pore veličine 13 &mu;m). Svaka od ovih grupa je dalje podeljena u jednu kontrolnu grupu i po četiri ispitivane grupe. Nakon sterilizacije uzoraka svaka kontrolna grupa je kontaminirana sa po 100&mu;l bakterijskog bujona Staphylococcus epidermidis (n=30), Staphylococcus aureus (n=30), Pseudomonas aeruginosa (n=30) i Ralstonia pickettii (n=30). Ispitivane grupe se bile podeljene prema načinima ispiranja na one u kojima su uzorci prvo ispirani: oktenidin &ndash; dihidrohloridom ili povidon jodom ili cefuroksimom ili kombinacijom povidon joda i dva antibiotika, pa potom kontaminirani sa po 100&mu;l bakterijskog bujona Staphylococcus epidermidis (n=30), Staphylococcus aureus (n=30), Pseudomonas aeruginosa (n=30) i Ralstonia pickettii (n=30). Po zavr&scaron;enoj kontaminaciji, uzorci su se inkubirali na temperaturi od 37&deg;C u trajanju od 96h, čime su stvoreni uslovi za formiranje biofilma. Nakon inkubacije, svaki pojedinačni uzorak je uronjen u sterilan tripton soja bujon, izlagan soničnoj energiji u trajanju od 1minuta i zatim vorteksiran 1 minut, čime je omogućeno odvajanje nastalog biofilma od implantata. Za ispitivanje sposobnosti formiranja biofilma kori&scaron;ćena je modifikovana tehnika sa mikrotitar pločom po Stepanoviću. Rezultati su pokazali da sve četiri ispitivane bakterije S. epidermidis, S. aureus, P. aeruginosa i Ralstonia pickettii statistički značajno vi&scaron;e stvaraju biofilm na implantatima sa porama veličine 50&ndash;900 &mu;m u odnosu na pore 70-150 &mu;m i u odnosu na pore veličine 13 &mu;m. Biofilm se statistički značajno vi&scaron;e stvara na porama veličine 70-150 &mu;m u odnosu na pore 13 &mu;m. Jedini izuzetak je Pseudomonas aeruginosa kod kojeg ne postoji statistični značajna razlika u produkciji biofilma na teksturisanim implantatima sa porama veličine 70-150 &mu;m u odnosu na one sa porama 13 &mu;m. TakoĎe, sve četiri ispitivane bakterije statistički značajano manje stvaraju biofilm nakon ispiranja povidon jodom, oktenidin-dihidrohloridom ili rastvorom antibiotika u sve tri grupe implantata, u odnosu na povr&scaron;ine koje nisu ispirane. Izuzetak je S. epidermidis u Grupi 3 kod kojeg nije utvrĎeno statistički značajno manje formiranje biofilma nakon ispiranja oktenidin dihidrohloridom u odnosu na neispiranje. Cefuroksim je bio efikasniji u sprečavanju formiranja biofilma sve četiri ispitivane bakterije u odnosu na neispiranje u Grupi 1, kao i za S. epidermidis i Ralstoniu Pickettii u Grupi 2. Cefuroksim se nije pokazao statistički značajno efikasnim u sprečavanju formiranja biofilma S. aureus i P. aeruginosa u Grupi 2, kao ni kod jedne bakterije u Grupi 3. Dalje je dokazano da su antiseptici (oktenidin-dihirohlorid i povidon jod) kao i me&scaron;avina povidon joda i dva antibiotika (cefuroksim i gentamicin), statistički značajno efikasnji od ispiranja samo antibiotikomcefuroksimom u smanjenju formiranja biofilma sve četiri ispitivane bakterije kod sva tri ispitivana, različito teksturisana silikonska implantata. Rezultati su pokazali da je ispiranje povidon jodom statistički značajno efikasnije u prevenciji stvaranja biofilma kod skoro svih ispitivanih bakterija od ispiranja oktenidin- dihidrohloridom u sve tri grupe implantata. Statistički značajna razlika nije utvrĎena u prevenciji stvaranja biofilma Staphylococcus aureusa kod sve tri grupe implantata prilikom ispiranja povidon jodom u odnosu na oktenidin- dihidrohlorid, kao i kod Ralsotnia pickettii u Grupi 2. Na osnovu rezultata ove studije, preporuka je da se koriste mikroteksturisani implantati kao i da se oni, pre ugradnje isperu povidon jodom ili me&scaron;avinom povidon jod i dva antibiotika (cefuroksim i gentamicin), u cilju prevencije stvaranja biofilma, a time i postoperativnih komplikacija koje mogu nastati nakon ugradnje implantata.</p> / <p>The most common complication after breast implant surgery is contracture of capsule, which is normally formed around implants as part of foreign body reaction. The most sincere complication after this kind of surgery is breast implant associated anaplastic large cell lymphoma (BIA-ALCL). The cause of these complications is still unknown. It is evident that capsular contracture (CC) is seen less frequently in patients with macro-textured implants and in those with implants covered with polyurethane foam. On the other hand, BIA-ALCL is diagnosed more frequently in patients with those, macro-textured implants. Subclinical infection, defined as an response of organism on presence of biofilm on the implant, is considered to be one of the most important etiologic factors for CC and BIA-ALCL. Biofilm is a conglomerate of microorganisms immersed into matrix, which protects them from influence of antibiotics and antiseptics. As it is impossible to eradicate biofilms with medicaments, many authors suggest different steps in order to avoid contamination of the implant during the operation and therefore, prevent the formation of biofilm. Among many tips, it is recommended to irrigate the pocket for breast implant and the implant itself, with some antiseptic or antibiotic solution. Up till now, there is no agreed consensus on the type of irrigation for different implants. Only personal experiences of a few authors have been published. Aims of this research were: to establish the possibility of biofilm formation of four different bacteria (Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa and Ralstonia pickettii) on three differently textured breast implants (with pore diameter of 70-150 &mu;m, 50&ndash;900 &mu;m and 13 &mu;m) in vitro; to examine whether the irrigation of implant with antiseptics (povidone iodine and octenidine dihydrochloride), antibiotics (cefuroxime) or mixture of povidone iodine and two antibiotics, before the contamination with bacteria, has an influence on the incidence on biofilm formation on three differently textured implants; and to examine the effect of antiseptics in contrast to the effect of antibiotics on biofilm formation on three differently textured breast implants. The study was conducted as a prospective research that took place at the Laboratory for microbiology, at the Institute of public health of Vojvodina in Novi Sad. For the experiment, three types of silicone breast implants were used with different pore sizes: 70-150 &mu;m, 50&ndash;900 &mu;m and 13 &mu;m. Samples were made by cutting each of these types of implants into pieces sized 1x1cm. There were 1440 samples in total. According to texture, samples were divided it three groups: Group 1 (pore size 70-150 &mu;m), Group 2 (pore size 50&ndash;900 &mu;m) and Group 3 (pore size 13 &mu;m). Furthermore, each of these groups was divided in one control and four test groups. After sterilisation of samples, every control group was contaminated with 100&mu;l of bacterial broth of Staphylococcus epidermidis (n=30), Staphylococcus aureus (n=30), Pseudomonas aeruginosa (n=30) and Ralstonia pickettii (n=30). Tested groups were divided according to type of irrigation into those where samples were firstly irrigated with either: octenidine dihydrochloride of povidone iodine or cefuroxime of mixture of povidone iodine with two antibiotics, and after the irrigation, contaminated with 100&mu;l bacterial broth of Staphylococcus epidermidis (n=30), Staphylococcus aureus (n=30), Pseudomonas aeruginosa (n=30) and Ralstonia pickettii (n=30). After contamination, samples were incubated on 37&deg;C for 96h, which created excellent conditions for biofilm formation. After incubation, each sample was dipped into sterile tripton soy broth, and then exposed to sonic energy for 1 minute and vortexed for 1 minute, which made biofilm separate from the implant. For testing the capability of biofilm formation, modified technique with microtitar plates described by Stepanović was used. Results show that all four examined bacteria S. epidermidis, S. aureus, P. aeruginosa and Ralstonia pickettii form more biofilm on implants with pore sizes 50&ndash;900 &mu;m compared to implants with pore size 70-150 &mu;m and those with 13 &mu;m. Statistical significance was found in biofilm formation on implants with pores 70-150 &mu;m compared to implants with pores 13 &mu;m. Furthermore, all four examined bacteria form statistically less biofilm after the irrigation with any of used solutions: povidone iodine, octenidine dihydrochloride, antibiotic solution of mixture of povidone iodine and two antibiotics, in all three groups of implants compared to surfaces that were not irrigated. The exception is S. epidermidis in Group 3, where no statistical significance was found on biofilm formation after the irrigation with octenidine dihydrochloride compared to non-irrigation. Cefuroxime was more efficient in biofilm prevention for all four tested bacteria compared to non-irrigation in Group 1 and for S. epidermidis and Ralstonia pickettii in Group 2. There was no statistical significance found in prevention of S. aureus i P. aeruginosa biofilms when irrigating with cefuroxime in Group 2, as well as for all tested bacteria in Group 3. Furthermore, it was verified that antiseptics (octenidin dihydrochloride and povidone iodine) and mixture of povidone iodine and two antibiotics (cefuroxime and gentamycin), were statistically more efficient in biofilm prevention of all four examined bacteria in all groups of implants, compared to irrigation with antibiotic-cefuroxime alone. Results show that irrigation with povidone iodine is statistically more efficient in biofilm prevention of almost all examined bacteria compared to irrigation with octenidine dihydrochloride in all groups of implants. There was not found any statistical significance in prevention of Staphylococcus aureus biofilm when irrigating with povidone iodine compared to octenidine dihydrochloride in all groups of implants, and also in biofilm prevention of Ralsotnia pickettii in Group 2. According to results of this research, it is recommended to use micro-textured implants and to irrigate them with povidone iodine or mixture of povidone iodine and two antibiotics (cefuroxime and gentamycin) prior the implementation, in order to prevent biofilm formation which is most probable cause of postoperative complications after implant surgery.</p>

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / PURPOSE: To assess the long-term effect of a 2% aqueous chlorhexidine (CHX) solution on bond strength to artificially eroded dentin compared to sound dentin. MATERIALS AND METHODS: Flat mid-coronal dentin surfaces of extracted third molars (n = 28) were subjected only to grinding with a 600-grit SiC paper for 1 min (sound dentin S, n = 14) or additionally to erosive pH cycling with a cola-based soft-drink (eroded dentin E, n = 14). After acid etching, rinsing, and air drying, S and E were rehydrated with 1.5 μl of 2% CHX (S2%, n = 7; E2%, n = 7) or of distilled water (control SC, n = 7; EC, n = 7). Composite buildups were incrementally constructed with Filtek Z350 following Adper Single Bond 2 application. Specimens were sectioned into beams, which were subjected to microtensile testing immediately or after 6 or 12 months of aging. Fractured surfaces were observed under a digital microscope (50X magnification). Microtensile bond strength (μTBS) (MPa) was analyzed by three-way ANOVA and Tukey's tests (α = 0.05) and failure mode by the Kruskal-Wallis test (α = 0.05). RESULTS: Compared to sound dentin, eroded dentin was consistently related to lower μTBS. Immediately and after 12-month aging, the effect of CHX was insignificant, but it was significant after 6-month aging, when it conserved the bond strength to both eroded and sound dentin. The percentage of adhesive and mixed failures were equivalent, and significantly more frequent than cohesive failures, whether in dentin or in composite. CONCLUSION: The 2% CHX effect on bond strength conservation to both eroded and sound dentin was not found to be persistent. / Revisión por pares

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / PURPOSE: To evaluate the effect of aqueous solutions of chlorhexidine digluconate (CHX) in different concentrations on bond strength to eroded dentin up to 6 months, using normal dentin as a control. METHODS: Exposed flat dentin of extracted third molars was only ground with 600-grit SiC paper/1 minute (normal dentin - N), or subsequently eroded by a regular-cola soft-drink (eroded dentin - E). N and E were acid-etched, washed, dried and rehydrated with 1.5 μL, respectively, of distillated water (control - NC / EC); of 0.004% CHX (N0.004% / E0.004%); or of 2% CHX (N2% / E2%). Adper Single Bond 2 was applied in all specimens and resin composite buildups were constructed with Filtek Z350. Specimens were sectioned in beams, which were tested (μTBS) immediately or after 6 months of aging. RESULTS: Microtensile bond strength to eroded dentin was always significantly lower than that to normal dentin. Application of tested CHX solutions did not exert a significant effect immediately; however, after aging, the 2% CHX prevented abrupt bond strength loss both to eroded and normal dentin. / Revisión por pares

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / PURPOSE: To assess the influence of simulated oral erosive/abrasive challenges on the bond strength of an etch-and-rinse two-step bonding system to enamel using an in situ/ex vivo protocol. METHODS: Bovine enamel blocks were prepared and randomly assigned to four groups: CONT - control (no challenge), ABR - 3x/day-1 minute toothbrushing; ERO - 3x/day - 5 minutes extraoral immersion into regular Coca Cola; and ERO+ABR - erosive protocol followed by a 1-minute toothbrushing. Eight blocks were placed into an acrylic palatal appliance for each volunteer (n = 13), who wore the appliance for 5 days. Two blocks were subjected to each of the four challenges. Subsequently, all the blocks were washed with tap water and Adper Single Bond 2/Filtek Z350 were placed. After 24 hours, 1 mm2 beams were obtained from each block to be tested with the microtensile bond strength test (50 N load at 0.5 mm/minute). The data were statistically analyzed by one-way RM-ANOVA and Tukey's tests (alpha = 0.05). RESULTS: No difference was detected among the ABR, ERO, and CONT groups (P > 0.05). ERO+ABR group yielded lower bond strengths than either the ABR and ERO groups (P < 0.0113). / Revisión por pares

Ziel dieser Arbeit war die Entwicklung neuer Methoden in der Rasterkraftmikroskopie, um die Qualität und Interpretierbarkeit von Oberflächenabbildungen auf der Nanometerskala, vor allem jener sehr weicher Proben, entscheidend zu verbessern. Der für polymere und biologische Materialien standardmäßig verwendete intermittierende Kontaktmodus führt auf weichen Oberflächen zu verfälschten Abbildungen der Topographie und der mechanischen Eigenschaften. In dieser Arbeit wurden Techniken entwickelt, die einerseits zerstörungsfreie, tiefenaufgelöste Rasterkraftmikroskopie und andererseits Einzelmessungen mit variabler Dämpfung im intermittierenden Kontaktmodus ermöglichen. Die laterale Auflösung beider Methoden liegt dabei im Rahmen herkömmlicher Techniken (< 10 nm). Die Tiefenauflösung konnte im Vergleich zu anderen Methoden um eine Größenordnung auf unter 1 nm verbessert werden. Die neuen Methoden wurden auf einer breiten Palette polymerer Materialien angewandt. Die räumliche Struktur oberflächennaher Bereiche eines Blockcopolymerfilms konnte im Vergleich zu herkömmlichen Methoden deutlich genauer abgebildet werden. Gleiches wurde auf elastomerem Polypropylen erreicht. Es konnten weiche, amorphe Deckschichten auf teilkristallinen Polymeren nachgewiesen und vermessen werden, was in der organischen Elektronik eine wichtige Rolle spielen kann. Die innere Struktur selbstangeordneter Nanodrähte aus Oligothiophen-Aggregaten konnte aufgelöst werden und es wurde die Selbstanordnung von Kollagenfibrillen im gequollenen Zustand beobachtet.

Les oxydes à base de Cérium, ont fait l’objet de nombreuses études ces dernières décennies et se sont révélés des matériaux de choix, dans le domaine de la catalyse hétérogène. L’objectif à l’heure actuelle, est donc d’accroître la réactivité de ces oxydes, tout en élargissant leur gamme de températures optimales d’utilisation. Dans ce contexte particulier, il semble possible de moduler les propriétés des oxydes à base de cérium en contrôlant la morphologie des cristallites. Ce travail de thèse a donc été consacré à la détermination, l’élaboration et à la caractérisation de matériaux oxydes à base de cérium de morphologies contrôlées. Nous avons tout d’abord déterminé cristallographiquement et thermodynamiquement les morphologies accessibles au système étudié puis par traitement hydrothermale assistée par chauffage micro-ondes nous avons synthétisé les dites morphologies. Après caractérisation de la réactivité par ATG et thermographie Infrarouge nous avons optimisé ces matériaux par un dopage extrinsèque tout d’abord (dépôt de métaux précieux), puis par un dopage intrinsèque ensuite (Yttrium et Fer). Enfin, l’obtention de morphologies non accessibles cristallographiquement nous a amené à approfondir le(s) processus de germination croissance de ces particules et la forte réactivité des matériaux dopés fer nous a poussé à une caractérisation fine de la microstructure de ces matériaux. Au final nous avons pu corréler l’influence de la morphologie des cristallites sur la réactivité propre de l’ensemble des familles de matériaux étudiés. / Recent decades, numerous studies on cerium-based oxides have been realized and have revealed that cerium-based oxides were materials of choice in the field of heterogeneous catalysis. The aim now is therefore to increase the reactivity of these oxides, while expanding their range of optimal temperatures of Use. In this particular context, it seems possible to modulate the properties of cerium-based oxides by controlling the morphology of the crystallites. This thesis has been devoted to the identification, development and characterization of materials based on cerium oxides of controlled morphology. We first determined possible morphologies for the studied system, by hydrothermal synthesis by micro-wave assisted heating we have synthesized these morphologies and we characterized reactivity of these materials by infrared thermography and TGA. We have optimized these materials first, by extrinsic doping (deposition of precious metals) and then by intrinsic doping (Yttrium and Iron). New morphologies have been synthesized so we have studied the processes of nucleation-growth set in. The high reactivity of iron-doped materials has led us to a detailed characterization of the microstructure of these materials. Finally correlation reactivity/morphologies of crystallites have been achieved.

No description available.

Ziel dieser Arbeit war die Entwicklung neuer Methoden in der Rasterkraftmikroskopie, um die Qualität und Interpretierbarkeit von Oberflächenabbildungen auf der Nanometerskala, vor allem jener sehr weicher Proben, entscheidend zu verbessern. Der für polymere und biologische Materialien standardmäßig verwendete intermittierende Kontaktmodus führt auf weichen Oberflächen zu verfälschten Abbildungen der Topographie und der mechanischen Eigenschaften. In dieser Arbeit wurden Techniken entwickelt, die einerseits zerstörungsfreie, tiefenaufgelöste Rasterkraftmikroskopie und andererseits Einzelmessungen mit variabler Dämpfung im intermittierenden Kontaktmodus ermöglichen. Die laterale Auflösung beider Methoden liegt dabei im Rahmen herkömmlicher Techniken (< 10 nm). Die Tiefenauflösung konnte im Vergleich zu anderen Methoden um eine Größenordnung auf unter 1 nm verbessert werden. Die neuen Methoden wurden auf einer breiten Palette polymerer Materialien angewandt. Die räumliche Struktur oberflächennaher Bereiche eines Blockcopolymerfilms konnte im Vergleich zu herkömmlichen Methoden deutlich genauer abgebildet werden. Gleiches wurde auf elastomerem Polypropylen erreicht. Es konnten weiche, amorphe Deckschichten auf teilkristallinen Polymeren nachgewiesen und vermessen werden, was in der organischen Elektronik eine wichtige Rolle spielen kann. Die innere Struktur selbstangeordneter Nanodrähte aus Oligothiophen-Aggregaten konnte aufgelöst werden und es wurde die Selbstanordnung von Kollagenfibrillen im gequollenen Zustand beobachtet.

La région boréale arctique (RBA) couvre une vaste étendue qui lui confère un rôle important dans le système climatique mondial, par ses échanges d'énergie et de matière avec l'atmosphère. La température de l'air dans la région boréale arctique a augmenté à des taux disproportionnés par rapport à la moyenne mondiale, entraînant des changements dans la composition et la structure de la végétation. La RBA comprend l'écotone de la forêt boréale et de la toundra (EFT), qui s'étend sur plus de 10,000 km à travers l'hémisphère nord. La structure et la composition de la végétation varient considérablement à travers l’EFT. Du sud au nord, les arbres deviennent plus courts, plus dispersés et finalement absents. Ce gradient entraîne des variations dans la balance énergétique de surface. Ainsi, des changements dans la composition et la structure de la végétation dans l’EFT pourraient influencer le climat régional futur de ces régions. Ces changements régionaux pourraient se répercuter sur le climat mondial en interagissant avec le cycle du carbone par des changements dans les régimes de perturbations et la profondeur de la couche limite atmosphérique. L'objectif de cette étude était de développer un état des lieux de la variation latitudinale des interactions entre la surface et l’atmosphère et du climat régional à travers l’EFT dans le nord-ouest du Canada. Nous avons utilisé des mesures de covariance des turbulences provenant d’une forêt subarctique en marge de l’EFT et d’une toundra minérale caractérisant l’EFT du nord-ouest du Canada afin de quantifier les différences journalière et saisonnières des échanges d'énergie. Quatre paramètres de surface (albédo, conductance aérodynamique, conductance de surface et facteur de découplage) ont été examinés dans le but d’expliquer les différences dans la balance énergétique de surface. Des observations par radiosonde basées sur des campagnes de terrain et une expérience de modélisation de la couche limite atmosphérique ont été réalisées afin de discuter des conséquences potentielles des changements de végétation sur la dynamique de la couche limite atmosphérique (hauteur, température, humidité) et ses implications pour le climat régional. La forêt subarctique a démontré une meilleure capacité à transférer la chaleur vers l’atmosphère et une plus grande résistance à l'évapotranspiration, se traduisant par des conditions atmosphériques plus chaudes et sèches, spécialement au printemps. En été et automne, une conductance de surface plus élevée sur le site de la toundra s’est traduite par à une plus grande proportion de l'énergie utilisée pour humidifier l'atmosphère, résultant en une couche atmosphérique moins épaisse et un refroidissement régional du climat. La caractérisation des interactions entre la surface et l’atmosphère à travers l’EFT contribuera à améliorer les prédictions des effets des changements de végétation en cours sur le climat régional dans la région boréale arctique. / Considering its vast extent, the Arctic-boreal region (ABR) plays an important role in the global climate system through its exchange of energy and matter with the atmosphere. Air temperature across the ABR has been increasing at a higher rate compared to the global average and has led to changes in vegetation composition and structure across the ABR. The ABR includes the forest-tundra ecotone (FTE), spanning more than 10,000 km across the northern hemisphere. As the world’s longest transition zone, the FTE separates the boreal and Arctic biomes over a width of only a few tens to hundreds of kilometers. Vegetation composition and structure varies considerably across the FTE as trees become, from south to north, shorter and more stunted, sparser, and eventually, absent. The associated latitudinal gradient in surface properties results in corresponding latitudinal variations in the energy balance. Thus, changes in the latitudinal variation in surface properties and energy exchanges within the atmospheric boundary layer (ABL) may affect future regional climate across the FTE. The goal of this study was to develop a baseline understanding of the latitudinal variation in surface-atmosphere interactions and atmospheric boundary layer dynamics across the FTE in northwestern Canada. We used paired eddy covariance measurements of surface energy fluxes and supporting environmental measurements at a subarctic woodland (‘woodland’) and a mineral upland tundra site (‘tundra’) to quantify differences in daily and seasonal differences in woodland and tundra properties and energy exchanges. Four bulk surface parameters (albedo, aerodynamic conductance, surface conductance, and decoupling factor) were examined to explain drivers of those differences. Campaign-based radiosonde observations and numerical experiments using an ABL model were used to examine the impacts of a sparse tree cover on ABL dynamics (height, temperature, humidity) and their implications for surface climate compared to treeless tundra. The sparse tree cover at the woodland site showed an enhanced ability to transfer heat into the atmosphere and a higher resistance to evapotranspiration compared to tundra, leading to warmer and drier conditions especially in late winter and spring. In summer and fall, higher bulk surface conductance at the tundra site led to more energy being used to moisten the atmosphere, resulting in a shallower ABL and regional cooling of the atmosphere. Refined characterization of land surface-atmosphere interactions across the FTE will help to project the effect of ongoing vegetation changes on regional climate in the circumpolar Arctic-boreal region.

Yes / A new type of self-assembled polyelectrolyte complex nanocarrier composed of chondroitin (CHON) and protamine (PROT) was designed and the ability of the carriers to bind salmon calcitonin (sCT) was examined. The response of sCT-loaded CHON/PROT NPs to a change in the properties of the liquid medium, e.g. its pH, composition or ionic strength was studied and in vitro peptide release was assessed. The biocompatibility of the NPs was evaluated in Caco-2 cells. CHON/PROT NPs were successfully obtained with properties that were dependent on the concentration of the polyelectrolytes and their mixing ratio. X-ray diffraction determined the amorphous nature of the negatively charged NPs, while those with the positive surface potential were semi-crystalline. sCT was efficiently associated with the nanocarriers (98-100%) and a notably high drug loading (13-38%) was achieved. The particles had negative zeta potential values and were homogenously dispersed with sizes between 60 and 250 nm. CHON/PROT NPs released less than 10% of the total loaded peptide in the first hour of the in vitro release studies. The enthalpy of the decomposition exotherm correlated with the amount of sCT remaining in NPs after the release experiments. The composition of medium and its ionic strength was found to have a considerable influence on the release of sCT from CHON/PROT NPs. Complexation to CHON markedly reduced the toxic effects exerted by PROT and the NPs were compatible and well tolerated by Caco-2 cells.