The directive of the European parliament and of the council on the Restriction of the use of certain Hazardous Substances (RoHS) in Electrical and Electronic Equipment (EEE) took effect in the European Union on July 1, 2006. Japan, California, China and Korea are all closed markets for exporters of components containing lead from July 1, 2007. Taiwan and Australia are working with similar directives. The RoHS directive is the reason why this thesis about the implementation of lead-free soldering in highly reliable applications is necessary. The European Lead Free soldering NETwork (ELFNET) status survey from 2005 shows that the majority of the companies are well informed, but 20% are still not active in lead-free soldering. The Swedish industry is for the most part prepared and 95% of the components are lead-free. The transition to lead-free soldering will have a major affect on logistics and administration, because the RoHS directive is 90% about administration and logistics problems. Only 10% is technical problems. The higher melting point in lead-free soldering affects every stage of the lead-free manufacturing, from assembly to testing and repair. The major concern for highly reliable applications are that there are not enough data to understand to what grade lead-free solders will perform differently from lead based solders. Five different types of reliability testing were studied in this thesis; vibration, mechanical shock, thermal shock, thermal cycling and combined environments. Whiskers, voids, brittle fractures and mixed assembly problems were also studied. Individual tests alone should not be used to make definite decisions on lead-free soldering reliability. The lower reliability for lead-free solders in some tests does not necessarily mean that lead-free solders not can be used in highly reliable applications like defence electronics. The most important conclusions from this thesis are: • Update or change the logistic system and mark/label according to available standards. • Secure a good board layout. • Secure a good process control. • Alternative surface board should be used. Tin-silver-copper (SAC) is the most reliable solder and Electroless Nickel/Immersion Gold (ENIG) is the most reliable surface finish. • Remember that the higher temperature affects every stage of the manufacturing. • No increased problems with whiskers or risk of high voiding levels. • Mixed assembly is a risk. Compatibility and contamination risks must be taken seriously. • Which environment will the applications be in? If it is not a highly vibrating and thermal cycling environment, lead-free soldering should be safe to use. / Europaparlamentets och rådets direktiv om begränsning av användningen av vissa farliga ämnen i elektriska och elektroniska produkter började gälla i Europeiska unionen 1 juli, 2006. Japan, Kalifornien, Kina och Korea är alla stängda marknader för exportörer av komponenter som innehåller bly från och med 1 juli, 2007. Taiwan och Australien arbetar med liknande direktiv. RoHS-direktivet är anledningen till varför detta examensarbete om implementeringen av blyfri lödning i högtillförlitliga applikationer är nödvändigt. En undersökning från 2005 av ELFNET visar att majoriteten av företagen är väl informerade, men 20% är fortfarande i aktiva med blyfri lödning. Den svenska industrin är till största delen väl förberedd och 95% av komponenterna är blyfria. Övergången till blyfri lödning kommer att ha stor effekt på logistik och administration, därför att 90% är administrations- och logistikproblem i RoHS-direktivet. Bara 10% är tekniska problem. Den högre smälttemperaturen i blyfri lödning påverkar varje steg av den blyfria tillverkningen, från montering till testning och reparation. Den stora oron för högtillförlitliga applikationer är att det inte finns tillräckligt med data för att förstå i vilken grad som blyfria lod kommer att bete sig annorlunda jämfört med blybaserade lod. Fem olika typer av tillförlitlighetstester har undersökts i detta examensarbete; vibration, mekanisk chock, termisk chock, termisk cykling och kombinerade tester. Whiskers, voids, sprödbrott och blandad montering studerades också. Individuella tester ska inte användas för att ta några definitiva beslut om blyfri lödnings tillförlitlighet. Den lägre tillförlitligheten för blyfria lod i en del tester behöver nödvändigtvis inte betyda att blyfria lod inte kan användas i högtillförlitliga applikationer som försvarselektronik. De viktigaste slutsatserna från detta examensarbete är: • Uppdatera eller byt logistiskt system och märk enligt tillgängliga standarder. • Säkerställ en bra kretskortsdesign. • Säkerställ en bra processkontroll. • Alternativa mönsterkort bör användas. SAC är det tillförlitligaste lodet och ENIG är den tillförlitligaste ytbehandlingen. • Kom ihåg att den ökade temperaturen påverkar varje steg i tillverkningen. • Inga ökade problem med whiskers eller stort antal voids. • Blandmontage är riskfyllt. Kompatibilitet och risker med kontaminering måste tas på allvar. • Vilken miljö kommer applikationen att befinna sig i? Är det inte en starkt vibrerande eller temperaturcyklisk miljö bör blyfri lödning vara säkert att använda.

Glass matrix composites containing a conducting filler such as antimony tin oxide (ATO) or silicon carbide whiskers (SiCw) have the potential for applications such as transparent electrodes, heating elements, and electromagnetic shielding. For these applications, the composite performance is highly dependent on the microstructure of the composite and the interactions the added filler has with one another. In this research, borosilicate glass-matrix composites were fabricated using a processing method that creates segregated percolated networks at low concentrations of conducting fillers. The conducting fillers were hot pressed with the glass microspheres at temperatures near the glass transition temperature (550°C) using various pressures. Upon hot-pressing at these low temperatures, the glass microspheres deformed into faceted polyhedra and the fillers were displaced to the edges of the glass particles, resulting in percolation. The processing method used in this study was able to bypass many of the current composition and densification issues associated with the creation of percolated networks in glass composites. In some cases, the formation of these percolated networks resulted in a 12-13 orders of magnitude decrease in the resistivity. Using a non-destructive electrical measurement technique, ac impedance spectroscopy (IS), the changes in the electrical properties were tracked as the conducting networks developed. Using IS in conjunction with other techniques, correlations were made between the electrical properties, the filler interfaces, and the influence the processing parameters had on the development of the percolation networks within these composites.

A stable aqueous nanocomposite dispersion containing cellulose whiskers and a polymer matrix was prepared via miniemulsion polymerization. We were able to prepare a stable dispersion with a 250 wt % solid content and a cellulose whiskers content ranging from 1 up to 5 wt % based on polymer content. Cellulose nanocrytals suspension was mixed with monomers phase in presence of anionic or cationic surfactant and a stabilizing additive acting as a hydrophobe. After sonication for a short time to obtain a stable emulsion of small droplet polymerisation reaction was trigged by the addition of the initiator. The nanocomposite dispersion was characterized using dynamic light scattering, ζ-potential measurement, transmission electron microscopy (TEM), atomic force microscopy (AFM) and FE-SEM. It was found that the particle size of the prepared suspensions is in the range of 90-600 nm, and the final nanocrystals composite is stable for months.Films obtained by casting followed by water evaporation and particle coalescence were analyzed by differential scanning calorimetry, dynamic mechanical analysis, and tensile testing. The nanocomposite maintained high transparency, and their storage elastic modulus increased tediously with the increasing nanowhiskers content.

This research explored the processing and properties of PNCs using a polyfurfural alcohol (PFA) matrix. The precursor for PFA, furfuryl alcohol (FA) is sourced from feedstocks rich in hemicellulose, such as corn cobs, oat hulls and wood. To exploit FA as a polymerizable solvent, cellulose whiskers (CW) and montmorillonite clay (MMT) were used as the nanoparticle phase. Results from PNC processing show that CW and MMT can be dispersed in the PFA matrix by means of insitu polymerization, without the use of surfactants or dilution in solvents. Both CW and MMT nanoparticles catalyze the polymerization of furfuryl alcohol (FA). Moreover, the insitu intercalative polymerization of FA in the interlayer galleries of MMT leads to the complete exfoliation of the MMT in the PFA matrix. CW and MMT both function as effective matrix modifiers, increasing the thermal stability of PFA nanocomposites compared to pure PFA polymer. The increased thermal stability is seen as significant increases in the onset of degradation and in residual weight at high temperature. This research also explored the surface functionalization of Cu, Ni and Pt substrates by self-assembly of a range of difunctional linker molecules. Characterization by XPS and PM-IRRAS indicate that diisocyanides and dicarboxylic acids both form chemically "sticky" surfaces after self-assembly on Cu and Ni. Sticky surfaces may provide a means of increasing nanoparticle dispersion in metal nanocluster filled PNCs, by increasing their interaction with the matrix polymer. Another potential application for sticky surfaces on Cu is in the ongoing miniaturization of circuit boards. The functionalization of Cu bond pad substrates with linker molecules may provide an alternate means of bonding components to their bond pads, with higher placement accuracy compared to solder bumps.

Physical, chemical and corrosion properties of a hexavalent chromium conversion coating (CCC) and that of a commercial third generation trivalent chromium system; Tripass LT1500, on zinc electrodeposited steel has been studied. Moreover, the role of additives has been studied to elucidate film formation and corrosion resistance mechanisms. Micro-cracking and self-repair corrosion protection behaviour commonly associated with hexavalent CCCs has also been investigated. Scanning Electron Microscopy (SEM) studies showed that for both hexavalent and trivalent CCCs were in general, flat with a spherical-like structure and in the case of the former microcracked beyond 122 nm conversion coating thickness. In general, the micro-crack pattern observed e.g. a dense crack network, depended upon the underlying zinc substrate morphology. The study has also demonstrated the effect of SEM imaging and prior specimen preparation conditions on hexavalent CCC micro-cracking and blistering. X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and Infrared (IR) data has indicated that the hexavalent CCC film formation appears to be a electrochemical/sol-gel mechanism given the lack of zinc content at surface and subsurface regions within the conversion coating, presence of H2O and in particular the contribution of Cr(OH)3 as opposed to Cr2O3. An alternative film formation mechanism may exist for trivalent CCC given a higher proportion of zinc at surface and sub-surface regions, IR data analysis indicating that chromium is possibly deposited from a chromium (III) complex ion such as [CrC2O4(H2O)4] + , moreover as Cr(OH)3 and Cr2O3 compounds as indicated by XPS data analysis. The role of cobalt nitrate during film formation is unclear given that cobalt was not detected within the trivalent CCC from XPS and AES data. Electrochemical LPR measurements, polarisation curves and XPS data has shown in general, self-repair corrosion protection properties for hexavalent CCC to be lacking. Instead, it is proposed that the corrosion protection behaviour for hexavalent and trivalent CCC to be barrier. Polarisation curves and LPR data showed that the corrosion resistance performance for trivalent CCC was higher than hexavalent CCC, in general. LPR data showed that the omission of cobalt nitrate and increased addition of sodium molybdate content within the Tripass LT1500 treatment solution formulation was found to overall decrease corrosion resistance within the trivalent CCC. In addition, silica based topcoat and black trivalent CCCs was also investigated and characterised using AES, SEM and LPR. Zinc whiskers was also observed from zinc electrodeposits following exposure to thermal treatment (150°C for 1 h). Elemental analysis and grain pattern investigations failed to help determine the cause of zinc whisker initiation. Zinc whiskers was seen to protrude out of hexavalent and trivalent CCCs, with the latter requiring a longer thermal exposure time.

abstract: Increasing density of microelectronic packages, results in an increase in thermal and mechanical stresses within the various layers of the package. To accommodate the high-performance demands, the materials used in the electronic package would also require improvement. Specifically, the damage that often occurs in solders that function as die-attachment and thermal interfaces need to be addressed. This work evaluates and characterizes thermo-mechanical damage in two material systems – Electroplated Tin and Sintered Nano-Silver solder. Tin plated electrical contacts are prone to formation of single crystalline tin whiskers which can cause short circuiting. A mechanistic model of their formation, evolution and microstructural influence is still not fully understood. In this work, growth of mechanically induced tin whiskers/hillocks is studied using in situ Nano-indentation and Electron Backscatter Diffraction (EBSD). Electroplated tin was indented and monitored in vacuum to study growth of hillocks without the influence of atmosphere. Thermal aging was done to study the effect of intermetallic compounds. Grain orientation of the hillocks and the plastically deformed region surrounding the indent was studied using Focused Ion Beam (FIB) lift-out technique. In addition, micropillars were milled on the surface of electroplated Sn using FIB to evaluate the yield strength and its relation to Sn grain size. High operating temperature power electronics use wide band-gap semiconductor devices (Silicon Carbide/Gallium Nitride). The operating temperature of these devices can exceed 250oC, preventing use of traditional Sn-solders as Thermal Interface materials (TIM). At high temperature, the thermomechanical stresses can severely degrade the reliability and life of the device. In this light, new non-destructive approach is needed to understand the damage mechanism when subjected to reliability tests such as thermal cycling. In this work, sintered nano-Silver was identified as a promising high temperature TIM. Sintered nano-Silver samples were fabricated and their shear strength was evaluated. Thermal cycling tests were conducted and damage evolution was characterized using a lab scale 3D X-ray system to periodically assess changes in the microstructure such as cracks, voids, and porosity in the TIM layer. The evolution of microstructure and the effect of cycling temperature during thermal cycling are discussed. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2018

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-11-27T15:18:54Z No. of bitstreams: 1 BrismarkGoesDaRocha_TESE.pdf: 14655007 bytes, checksum: f132218e797f47b22250ea1afea1399e (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2015-11-30T21:25:07Z (GMT) No. of bitstreams: 1 BrismarkGoesDaRocha_TESE.pdf: 14655007 bytes, checksum: f132218e797f47b22250ea1afea1399e (MD5) / Made available in DSpace on 2015-11-30T21:25:07Z (GMT). No. of bitstreams: 1 BrismarkGoesDaRocha_TESE.pdf: 14655007 bytes, checksum: f132218e797f47b22250ea1afea1399e (MD5) Previous issue date: 2014-07-30 / O presente trabalho tem como objetivos extrair a fibra da folha do abacaxizeiro tipo P?rola para obter bast?es (?whiskers) de celulose destas fibras tratadas quimicamente, para utiliza??o como refor?o na fabrica??o de filmes de Biocomp?sito com Poli ?lcool Vin?lico (PVA) e Poli (?cido l?tico) (PLA) como matrizes. As amostras foram caracterizadas utilizando an?lises como TGA, FTIR e DSC. Tamb?m foram realizados ensaios das folhas para a identifica??o de macro e micro nutrientes. As amostras dos filmes de biocomp?sitos foram usadas para ensaios mec?nicos de tra??o nos filmes e o teste de biodegrada??o aer?bica, bem como nos filmes de 100% de PVA e PLA. A extra??o da fibra foi efetuada numa desfibradeira autom?tica, e em seguida as fibras extra?das foram lavadas v?rias vezes para remover as impurezas e foram tratadas com NaOH (hidr?xido de s?dio) e NaClO (hipoclorito de s?dio), para remover as impurezas inerentes ?s fibras e a cor natural, respectivamente. Em seguida, as fibras tratadas foram submetidas a um processo de hidr?lise com ?cido sulf?rico a 13,5%, para obten??o de bast?es de celulose. Foram produzidos filmes biocomp?sitos de PVA e PLA com bast?es de celulose nas concentra??es de 0%, 1%, 3%, 6%, 9% e 12%. ?gua destilada a 80?C ? 5 na dilui??o de PVA e diclorometano para a dilui??o do PLA na temperatura ambiente. Na prepara??o dos filmes foi utilizado o m?todo de ?casting?. Posteriormente foram realizados os testes de absor??o de ?gua pelos filmes produzidos. Para o ensaio mec?nico de tra??o dos filmes foi utilizada a norma ASTM D638-10 com velocidade de 50 mm/min. O teste estat?stico Qui-quadrado foi empregado para a verifica??o da exist?ncia de diferen?as significativas em n?vel de 0,05: comprimentos das folhas do abacaxizeiro e dos bast?es, procedimentos utilizados para filtra??o em filtro utilizando seringa de 0,2 ?m e filtragem atrav?s de centrifuga??o. Foi realizado estudo de hidrofilidade dos filmes com base no ?ngulo de contato. Tamb?m foi aplicado o teste Estat?stico T-Student com n?vel de signific?ncia (0,05) para comparar as espessuras dos filmes de PVA e PLA e das propriedades mec?nicas (tra??o). Na avalia??o da biodegradabilidade dos biocomp?sitos, bem como os filmes de 100% das matrizes de PVA e PLA, foi utilizado o teste de Sturm norma D5209. Os resultados indicam a presen?a de bast?es de celulose com comprimentos variandos de 7,33 nm a 186,17 nm. As espessuras em m?dia dos filmes de PVA e PLA eram de 0,153 ?m e 0,210 ?m, respectivamente. Foi observada uma forte correla??o linear diretamente proporcional entre a tra??o dos filmes de PVA e a concentra??o de bast?es de celulose nos filmes (0,7336), da espessura do filme de 0,1404. Juntos, a porcentagem de bast?es de celulose e a espessura dos filmes, correlacionaram 0,8740. No caso dos filmes de PLA, a correla??o entre o teor dos bast?es de celulose e a tra??o foi fraca, inversamente proporcional (-0,0057) e a espessura em -0,2602, totalizando -0,2659, isto ?, os bast?es de celulose n?o aderiram totalmente ao PLA. Na compara??o dos resultados da tra??o das duas matrizes polim?ricas, os bast?es de celulose contribu?ram na melhoria das propriedades mec?nicas no caso de PVA, mas h? uma diferen?a com rela??o a PLA. Nos testes de biodegradabilidade, foi observado a degrada??o total do filme de PVA ap?s 27 dias, enquanto o filme de PLA degradou em 20 dias, o que comprova que os filmes produzidos s?o biodegrad?veis. / This work has the main objective to obtain nano and microcrystals of cellulose, extracted from the pineapple leaf fibres (PALF), as reinforcement for the manufacture of biocomposite films with polymeric matrices of Poly(vinyl alcohol) (PVA) and Poly(lactic acid) (PLA). The polymer matrices and the nano and microcrystals of cellulose were characterised by means of TGA, FTIR and DSC. The analysis was performed on the pineapple leaves to identify the macro and micronutrients. The fibers of the leaves of the pineapple were extracted in a desfibradeira mechanical. The PALF extracted were washed to remove washable impurities and subsequently treated with sodium hydroxide (NaOH) and sodium hypochlorite (NaClO) in the removal of impurities, such as fat, grease, pectates, pectin and lignin. The processed PALF fibers were hydrolysed in sulfuric acid (H2SO4) at a concentration of 13.5 %, to obtain nano and microcrystals of cellulose. In the manufacture of biocomposite films, concentrations of cellulose, 0 %, 1 %, 3 %, 6 %, 9% and 12% were used as reinforcement to the matrices of PVA and PLA. The PVA was dissolved in distilled water at 80 ? 5 oC and the PLA was dissolved in dichloromethane at room temperature. The manufacture of biocomp?sitos in the form of films was carried out by "casting". Tests were carried out to study the water absorption by the films and mechanical test of resistance to traction according to ASTM D638-10 with a velocity of 50 mm/min.. Chi-square statistical test was used to check for the existence of significant differences in the level of 0.05: the lengths of the PALF, lengths of the nano and microcrystals of cellulose and the procedures used for the filtration using filter syringe of 0.2 ?m or filtration and centrifugation. The hydrophilicity of biocomp?sitos was analysed by measuring the contact angle and the thickness of biocomp?sitos were compared as well as the results of tests of traction. Statistical T test - Student was also applied with the significance level (0.05). In biodegradation, Sturm test of standard D5209 was used. Nano and microcrystals of cellulose with lengths ranging from 7.33 nm to 186.17 nm were found. The PVA films showed average thicknesses of 0.153 ?m and PLA 0.210 ?m. There is a strong linear correlation directly proportional between the traction of the films of PVA and the concentration of cellulose in the films (composite) (0,7336), while the thickness of the film was correlated in 0.1404. Nano and microcrystals of cellulose and thickness together, correlated to 0.8740. While the correlation between the cellulose content and tensile strength was weak and inversely proportional (- 0,0057) and thickness in -0.2602, totaling -0,2659 in PLA films. This can be attributed to the nano and microcrystals of cellulose not fully adsorbed to the PLA matrix. In the comparison of the results of the traction of the two polymer matrices, the nano and microcrystals have helped in reducing the traction of the films (composite) of PLA. There was still the degradation of the film of PVA, within a period of 20 days, which was not seen in the PLA film, on the other hand, the observations made in the literature, the average time to start the degradation is above 60 days. What can be said that the films are biodegradable composites, with hydrophilicity and the nano and microcrystals of cellulose, contribute positively in the improvement of the results of polymer matrices used.

Composites, in which the matrix and the reinforcing fillers are respectively, poly(acrylic acid) (PAA) with two different molecular weights, and chitin whiskers (CHW) were successfully prepared using an evaporation method. The weight fraction of CHW was varied from 0.03 to 0.73. Mechanical and thermal properties and crystallinity of the composites were characterised using tensile testing, differential scanning calorimetry, thermogravimetric analysis and X-ray diffraction. The tensile strength of the composite increased up to 11 wt % CHW after which it decreased. XRD characterisation showed a decrease in crystalline index, crystalline size, chitin crystalline peak and intensity as the content of PAA and its molecular weight increased. Raman spectroscopy was used for the first time to monitor the deformation of chitin film and CHW reinforced PAA composites. The Raman band located at 1622 cm^(-1) was monitored for deformation. On application of tensile deformation the Raman band initially located at 1622 cm^(-1) shifted toward a lower wavenumber. Raman band shift rates of -1.85 cm^(-1)/% for chitin film and -0.59 and -0.25 cm^(-1)/% for 73 and 23 wt % CHW content, respectively, were measured. The modulus of a single chitin whisker and composites were found to be 115, 37 and 16 GPa respectively, for a two dimensional (2D) in-plane distribution of CHW. CHW within a PAA matrix did not show any preferential alignment in a polarised Raman. The Raman intensity ratio〖 I〗_1698 /I_1622 showed that the strongest interaction of the carboxylic group in the composites occured at 3 wt % CHW content. The interaction gradually reduced as the CHW content increased. 〖 CaCO〗_3 crystals were grown in CHW, PAA and CHW/PAA composites by a solution and evaporation casting method. In the absence of PAA and CHW, rhombohedral calcites were observed while rod-like aragonite polymorphs were seen when only PAA was used as a template. In the presence of only CHW, a morphological mixture of ellipsoidal and disc shape with traces of rhombohedral aggregate calcite were the features. In the presence of both PAA and CHW, the rhombohedral shape showed roughness with irregular faces while the vaterite polymorph continued to agglomerate with the observation of porosity at higher CHW content. The vaterite particles gradually decreased as the CHW content was decreased. At lower CHW content aragonite polymorph growth was favoured to the detriment of calcite. The results showed that the vaterite polymorph can be grown even at higher filler loading. The effect of 〖 CaCO〗_3 growth on the mechanical properties of CHW reinforced PAA indicated that better mechanical properties can be achieved at a CHW content of 3 wt % when compared with neat PAA and when 〖 CaCO〗_3 was not incorporated into the CHW/25PAA composites.

This diploma thesis is about ZnO nanowires growth, their doping and analysis. High temperature and pressure oxidation of brass foil and deposition from effusion cell in oxidative atmosphere utilized for nanowires growth. The growth is affected by different temperature and pressure. It has been shown that under certain experimental conditions nanowires can be prepared by the former method. However, the growth was hindered when effusion cell was used.

Diese aus drei verschiedenen Studien bestehende Arbeit trägt mittels Verknüpfung von Anatomie (Struktur) und Physiologie oder Verhalten (Funktion) zu einem besseren Verständnis von somatosensorischer Informationsverarbeitung bei. In der ersten Studie untersuchten wir wie das Nervensystem der Ratte sich an das kontinuierliche Nachwachsen und Ausfallen der Tasthaare anpasst. Unsere Ergebnisse zeigen, dass Barrel-Kortex Neurone nach Auslenkung von sowohl jungen oder alten Tasthaaren ähnliche neuronale Antworten aufweisen. Wir konnten auch beobachten, dass junge und alte Tasthaare gemeinsam im Follikel innerviert werden und im Kortex nicht separat topologisch repräsentiert sind. Diese Ergebnisse könnten erklären wie die Stabilität von Wahrnehmung während fortlaufenden körperlich-sensorischen Veränderungen gewährleistet wird. In der zweiten Studie identifizierten wir Details der kortikalen Nasen Repräsentation und konnten zeigen, dass die Organisation von Schicht 4 im Somatosensorischen Kortex in Nagetieren konserviert ist. Wir fanden auch eine Kopplung von Nervenzellaktivität mit der Atmung, was für eine koordinierte Verarbeitung von Tastsinn und Atmung im Nasen-Somatosensorischen Kortex spricht. In der dritten Studie charakterisierten wir die kortikale Repräsentation der Schnauze im Hausschwein und konnten zeigen, dass dessen makroskopische, drei-dimensionale Erscheinung viele Details aufweist, die auch bei der tatsächlichen Schnauze zu finden sind. Ähnlich wie bei unseren histologischen Beobachtungen im Nasen- Somatosensorischen Kortex von Nagern konnten wir im Hausschwein Kortex eine Verjüngung von Schicht 4 der mutmaßlichen Repräsentation des Nasenlochs beobachten. Zusammengefasst zeigt diese Arbeit i) einen potentiellen Mechanismus für Kontinuität der Wahrnehmung während körperlichen Veränderungen ii) Details der kortikalen Nasen-Repräsentation und dessen Verhältnis zur Atmung und iii) isomorphe Eigenschaften der kortikalen Schnauzen-Repräsentation im Hausschwein. / Topological mapping of body part representations in the brain have long been studied in neuroscience. In this thesis, three separate studies investigate such somatosensory representations by relating anatomy (structure) to physiology or behavior (function). In the first study we investigated whether and how the rat nervous system adapts to whiskers regrowth. We found that barrel cortex neurons displayed similar response properties to young and old whisker deflection and that both whiskers share their peripheral innervation in the same follicle. Our results further suggest that young and old whiskers do not form topologically distinct representations in the cortex. Such findings illuminate how perceptual stability is maintained despite the constant change of bodies and sensory structures. In the second study we identified the rodent nose somatosensory cortex and found that its tangential layer 4 organization is conserved across rodents. We also found significant respiration locked neural activity in the rat nose somatosensory cortex, suggesting coordinated processing of touch and respiration. In the third study we characterized the pig rostrum somatosensory cortex and found that its three-dimensional, gross organization matches the detailed structure of the actual rostrum appearance. We also found that layer 4 appears thinner in the putative nostril, similar to our results in the rodent nose somatosensory cortex. Collectively, our data i) reveal potential mechanisms for perceptual stability during bodily changes ii) identify the rodent nose somatosensory cortex and its relationship to respiration and iii) a striking isomorphism of the pig cortical rostrum representation with the pig snout.