Scaling predictions for radii of weakly bound triatomic molecules

The mean-square radii of the triatomic molecules 4He 3, 4He 2- 6Li, 4He 2- 7Li, and 4He 2- 23Na were calculated using a renormalized three-body model with a pairwise Dirac-δ interaction, having as physical inputs only the values of the binding energies of the diatomic and triatomic molecules. Molecular three-body systems with bound subsystems were considered. The resultant data were analyzed in detail.

Kinetics of martensitic phase decomposition in the Cu-10wt.%Al alloy with Ag additions

The study of the kinetics of martensitic phase decomposition in the Cu-10wt.%Al alloy with Ag additions showed that the presence of Ag retarded the eutectoid decomposition reaction and enhanced martensite stabilization. This stabilization effect was attributed to Ag atoms redistribution as structure defects, increase in the numbers of Cu-Al pairs due to Ag-Al interaction and the Al atoms redistribution around one Cu atom at the sub-lattice of the martensitic crystal. © 2008 Trans Tech Publications.

Propriedades nanoestruturais de géis de sílica preparados com adiçoes de surfactante anionico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo in vitro de braquetes ortodônticos: avaliação biomecânica e liberação de íons

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Lithium intercalation into double rare earth chromates

Lithium intercalation into double rare earth chromates was carried out. It was found that the compounds NaxLi1-xLa(CrO4)2 belong to the NaLa(CrO4)2 structural type and may be recommended as fast ionic conductors. At small values of x a third polymorphous modification of LiLa(CrO4)2 can be stabilized. Attempts to intercalate lithium into CsLa(CrO4)2 lead to collapse of the lamellar network with the formation of LaCrO4 and alkaline chromates. Ion exchange Li+/H+ data are consistent with these considerations. © 1994.

Impact of bleaching pine fibre on the fibre/cement interface

The goal of this article was to evaluate the surface characteristics of the pine fibres and its impact on the performance of fibre-cement composites. Lower polar contribution of the surface energy indicates that unbleached fibres have less hydrophilic nature than the bleached fibres. Bleaching the pulp makes the fibres less stronger, more fibrillated and permeable to liquids due to removal the amorphous lignin and its extraction from the fibre surface. Atomic force microscopy reveals these changes occurring on the fibre surface and contributes to understanding the mechanism of adhesion of the resulting fibre to cement interface. Scanning electron microscopy shows that pulp bleaching increased fibre/cement interfacial bonding, whilst unbleached fibres were less susceptible to cement precipitation into the fibre cavities (lumens) in the prepared composites. Consequently, bleached fibre-reinforced composites had lower ductility due to the high interfacial adhesion between the fibre and the cement and elevated rates of fibre mineralization.

Hybrid density functional study of small Rh-n (n=2-15) clusters

The physical properties of small rhodium clusters, Rh-n, have been in debate due to the shortcomings of density functional theory (DFT). To help in the solution of those problems, we obtained a set of putative lowest energy structures for small Rh-n (n = 2-15) clusters employing hybrid-DFT and the generalized gradient approximation (GGA). For n = 2-6, both hybrid and GGA functionals yield similar ground-state structures (compact), however, hybrid favors compact structures for n = 7-15, while GGA favors open structures based on simple cubic motifs. Thus, experimental results are crucial to indicate the correct ground-state structures, however, we found that a unique set of structures (compact or open) is unable to explain all available experimental data. For example, the GGA structures (open) yield total magnetic moments in excellent agreement with experimental data, while hybrid structures (compact) have larger magnetic moments compared with experiments due to the increased localization of the 4d states. Thus, we would conclude that GGA provides a better description of the Rh-n clusters, however, a recent experimental-theoretical study [ Harding et al., J. Chem. Phys. 133, 214304 (2010)] found that only compact structures are able to explain experimental vibrational data, while open structures cannot. Therefore, it indicates that the study of Rh-n clusters is a challenging problem and further experimental studies are required to help in the solution of this conundrum, as well as a better description of the exchange and correlation effects on the Rh n clusters using theoretical methods such as the quantum Monte Carlo method.

Spin Orbit Effects in the Electronic Transport Properties of Adsorbed Graphene Nanoribbons

Graphene has received great attention due to its exceptional properties, which include corners with zero effective mass, extremely large mobilities, this could render it the new template for the next generation of electronic devices. Furthermore it has weak spin orbit interaction because of the low atomic number of carbon atom in turn results in long spin coherence lengths. Therefore, graphene is also a promising material for future applications in spintronic devices - the use of electronic spin degrees of freedom instead of the electron charge. Graphene can be engineered to form a number of different structures. In particular, by appropriately cutting it one can obtain 1-D system -with only a few nanometers in width - known as graphene nanoribbon, which strongly owe their properties to the width of the ribbons and to the atomic structure along the edges. Those GNR-based systems have been shown to have great potential applications specially as connectors for integrated circuits. Impurities and defects might play an important role to the coherence of these systems. In particular, the presence of transition metal atoms can lead to significant spin-flip processes of conduction electrons. Understanding this effect is of utmost importance for spintronics applied design. In this work, we focus on electronic transport properties of armchair graphene nanoribbons with adsorbed transition metal atoms as impurities and taking into account the spin-orbit effect. Our calculations were performed using a combination of density functional theory and non-equilibrium Greens functions. Also, employing a recursive method we consider a large number of impurities randomly distributed along the nanoribbon in order to infer, for different concentrations of defects, the spin-coherence length.

Parapoxvirus: basi genomiche della patogenesi

Parapoxvirus (PPV) are member of a genus in the family poxviridae which currently encompasses four species: the prototype orf virus (OV), bovine papular stomatitis virus (BPSV), pseudocowpox virus (PCPV) and parapoxvirus of New Zealand red deer (PVNZ). PPVs cause widespread, but localized diseases of small and large ruminants and they can also be transmitted to man. Knowledge of the molecular biology of PPV is still limited as compared to orthopoxviruses, especially vaccinia virus (VACV). The PPV genome displays a high G+C content and relatively small size for poxvirus. Coventional electron microscopy displays PPV virions with ovoid shape and slightly smaller in size than the brickshaped orthopoxviruses. The most striking feature, which readily enables identification of PPV, is a tubule-like structure that surrounds the particle in a spiral fashion. PPV genome organization and content is very similar to that of other poxviruses, the central region contain 88 genes which are present in all poxviruse, in contrast the terminal regions are variable and contain a set of genes unique to the genus PPV. Genes in the near-terminal regions of the genome are frequently not essential for growth in cultured cells encoding factors with important roles in virushost interactions including modulating host immune responses and determining host range. Recently it was suggested that the open reading frames (ORFs) 109 and 110 of the OV genome have a major role in determining species specificity during natural infection in sheep and goats. This hypothesis is based on the analysis of a few number of sequences of different sheep and goats viral isolates. PPV replicate into the cytoplasm of infected cells and produce three structurally different infectious particles: the intracellular mature virions (IMV), intracellular enveloped virions (IEV) and the extracellular enveloped virions (EEV). The vaccinia A33R and A34R hotologue proteins encoded by the ORFS 109 and 110 are expressed in the envelope of the IEV and EEV. The F1L immunodominant protein of orf virus is the major component of the surface tubule structure of the IMV and can post-translationaly insert into membranes via Cterminal, hydrofobic anchor sequence like its orthologue VACV H3L protein. Moreover the F1L protein binds to glycosaminoglycans on the cell surface and has an important role in IMV adsorption to mammalian cells. In this study we investigated the morphogenesis of the PPV through the construction of a mutant virus deleted of the F1L protein. A study of the deleted virus life cycle was conducted in different type of cells and its morphology was observed with electron microscopy. It was demonstared that F1L protein have important role in morphogenesis and infectivity. Moreover it is essential to determine the spiral fashion of the tubule like structure of the virion surface. Some pathogenetic aspects of the PPV infection were studied, in particular the protein implicated in the host range were analysed in detail. An experimental infection with OV and PCPV was conducted in goats and sheep. After infection, the severity of the lesions were comparable in both the animal species. The OV did not result in severe disease neither in sheep nor in goats, suggesting that host factors, rather than virus strain characteristics, may play an important role in the pathogenesis of the Parapoxvirus infections. The PCPV failed to produce any lesion in both sheep and goats, ruling out the possibility of any recombination between PCPV and OV during natural infection in these animal species. The phylogenetic analysis of the ORFs 109 and 110 from several goats and sheep viral isolates showed a clustering based on the antigenic content of the protein that was independent from species and geographic origin.

Rafael Moneo: la complessità del vuoto. Dalle matrici formali dell'opera di Oteiza e Chillida

The experience of void, essential to the production of forms and to make use them, can be considered as the base of the activities that attend to the formative processes. If void and matter constitutes the basic substances of architecture. Their role in the definition of form, the symbolic value and the constructive methods of it defines the quality of the space. This job inquires the character of space in the architecture of Moneo interpreting the meaning of the void in the Basque culture through the reading of the form matrices in the work of Jorge Oteiza and Eduardo Chillida. In the tie with the Basque culture a reading key is characterized by concurring to put in relation some of the theoretical principles expressed by Moneo on the relationship between place and time, in an unique and specific vision of the space. In the analysis of the process that determines the genesis of the architecture of Moneo emerges a trajectory whose direction is constructed on two pivos: on the one hand architecture like instrument of appropriation of the place, gushed from an acquaintance process who leans itself to the reading of the relations that define the place and of the resonances through which measuring it, on the other hand the architecture whose character is able to represent and to extend the time in which he is conceived, through the autonomy that is conferred to them from values. Following the trace characterized from this hypothesis, that is supported on the theories elaborated from Moneo, surveying deepens the reading of the principles that construct the sculptural work of Oteiza and Chillida, features from a search around the topic of the void and to its expression through the form. It is instrumental to the definition of a specific area that concurs to interpret the character of the space subtended to a vision of the place and the time, affine to the sensibility of Moneo and in some way not stranger to its cultural formation. The years of the academic formation, during which Moneo enters in contact with the Basque artistic culture, seem to be an important period in the birth of that knowledge that will leads him to the formulation of theories tied to the relationship between time, place and architecture. The values expressed through the experimental work of Oteiza and Chillida during years '50 are valid bases to the understanding of such relationships. In tracing a profile of the figures of Oteiza and Chillida, without the pretension that it is exhaustive for the reading of the complex historical period in which they are placed, but with the needs to put the work in a context, I want to be evidenced the important role carried out from the two artists from the Basque cultural area within which Moneo moves its first steps. The tie that approaches Moneo to the Basque culture following the personal trajectory of the formative experience interlaces to that one of important figures of the art and the Spanish architecture. One of the more meaningful relationships is born just during the years of his academic formation, from 1958 to the 1961, when he works like student in the professional office of the architect Francisco Sáenz de Oiza, who was teaching architectural design at the ETSAM. In these years many figures of Basque artists alternated at the professional office of Oiza that enjoys the important support of the manufacturer and maecenas Juan Huarte Beaumont, introduced to he from Oteiza. The tie between Huarte and Oteiza is solid and continuous in the years and it realizes in a contribution to many of the initiatives that makes of Oteiza a forwarder of the Basque culture. In the four years of collaboration with Oiza, Moneo has the opportunity to keep in contact with an atmosphere permeated by a constant search in the field of the plastic art and with figures directly connected to such atmosphere. It’s of a period of great intensity as in the production like in the promotion of the Basque art. The collective “Blanco y Negro”, than is held in 1959 at the Galería Darro to Madrid, is only one of the many times of an exhibition of the work of Oteiza and Chillida. The end of the Fifties is a period of international acknowledgment for Chillida that for Oteiza. The decade of the Fifties consecrates the hypotheses of a mythical past of the Basque people through the spread of the studies carried out in the antecedent years. The archaeological discoveries that join to a context already rich of signs of the prehistoric era, consolidate the knowledge of a strong cultural identity. Oteiza, like Chillida and other contemporary artists, believe in a cosmogonist conception belonging to the Basques, connected to their matriarchal mythological past. The void in its meaning of absence, in the Basque culture, thus as in various archaic and oriental religions, is equivalent to the spiritual fullness as essential condition to the revealing of essence. Retracing the archaic origins of the Basque culture emerges the deep meaning that the void assumes as key element in the religious interpretation of the passage from the life to the death. The symbology becomes rich of meaningful characters who derive from the fact that it is a chthonic cult. A representation of earth like place in which divine manifest itself but also like connection between divine and human, and this manipulation of the matter of which the earth it is composed is the tangible projection of the continuous search of the man towards God. The search of equilibrium between empty and full, that characterizes also the development of the form in architecture, in the Basque culture assumes therefore a peculiar value that returns like constant in great part of the plastic expressions, than in this context seem to be privileged regarding the other expressive forms. Oteiza and Chillida develop two original points of view in the representation of the void through the form. Both use of rigorous systems of rules sensitive to the physics principles and the characters of the matter. The last aim of the Oteiza’s construction is the void like limit of the knowledge, like border between known and unknown. It doesn’t means to reduce the sculptural object to an only allusive dimension because the void as physical and spiritual power is an active void, that possesses that value able to reveal the being through the trace of un-being. The void in its transcendental manifestation acts at the same time from universal and from particular, like in the atomic structure of the matter, in which on one side it constitutes the inner structure of every atom and on the other one it is necessary condition to the interaction between all the atoms. The void can be seen therefore as the action field that concurs the relations between the forms but is also the necessary condition to the same existence of the form. In the construction of Chillida the void represents that counterpart structuring the matter, inborn in it, the element in absence of which wouldn’t be variations neither distinctive characters to define the phenomenal variety of the world. The physics laws become the subject of the sculptural representation, the void are the instrument that concurs to catch up the equilibrium. Chillida dedicate himself to experience the space through the senses, to perceive of the qualities, to tell the physics laws which forge the matter in the form and the form arranges the places. From the artistic experience of the two sculptors they can be transposed, to the architectonic work of Moneo, those matrices on which they have constructed their original lyric expressions, where the void is absolute protagonist. An ambit is defined thus within which the matrices form them drafts from the work of Oteiza and Chillida can be traced in the definition of the process of birth and construction of the architecture of Moneo, but also in the relation that the architecture establishes with the place and in the time. The void becomes instrument to read the space constructed in its relationships that determine the proportions, rhythms, and relations. In this way the void concurs to interpret the architectonic space and to read the value of it, the quality of the spaces constructing it. This because it’s like an instrument of the composition, whose role is to maintain to the separation between the elements putting in evidence the field of relations. The void is that instrument that serves to characterize the elements that are with in the composition, related between each other, but distinguished. The meaning of the void therefore pushes the interpretation of the architectonic composition on the game of the relations between the elements that, independent and distinguished, strengthen themselves in their identity. On the one hand if void, as measurable reality, concurs all the dimensional changes quantifying the relationships between the parts, on the other hand its dialectic connotation concurs to search the equilibrium that regulated such variations. Equilibrium that therefore does not represent an obtained state applying criteria setting up from arbitrary rules but that depends from the intimate nature of the matter and its embodiment in the form. The production of a form, or a formal system that can be finalized to the construction of a building, is indissolubly tied to the technique that is based on the acquaintance of the formal vocation of the matter, and what it also can representing, meaning, expresses itself in characterizing the site. For Moneo, in fact, the space defined from the architecture is above all a site, because the essence of the site is based on the construction. When Moneo speaks about “birth of the idea of plan” like essential moment in the construction process of the architecture, it refers to a process whose complexity cannot be born other than from a deepened acquaintance of the site that leads to the comprehension of its specificity. Specificity arise from the infinite sum of relations, than for Moneo is the story of the oneness of a site, of its history, of the cultural identity and of the dimensional characters that that they are tied to it beyond that to the physical characteristics of the site. This vision is leaned to a solid made physical structure of perceptions, of distances, guideline and references that then make that the process is first of all acquaintance, appropriation. Appropriation that however does not happen for directed consequence because does not exist a relationship of cause and effect between place and architecture, thus as an univocal and exclusive way does not exist to arrive to a representation of an idea. An approach that, through the construction of the place where the architecture acquires its being, searches an expression of its sense of the truth. The proposal of a distinction for areas like space, matter, spirit and time, answering to the issues that scan the topics of the planning search of Moneo, concurs a more immediate reading of the systems subtended to the composition principles, through which is related the recurrent architectonic elements in its planning dictionary. From the dialectic between the opposites that is expressed in the duality of the form, through the definition of a complex element that can mediate between inside and outside as a real system of exchange, Moneo experiences the form development of the building deepening the relations that the volume establishes in the site. From time to time the invention of a system used to answer to the needs of the program and to resolve the dual character of the construction in an only gesture, involves a deep acquaintance of the professional practice. The technical aspect is the essential support to which the construction of the system is indissolubly tied. What therefore arouses interest is the search of the criteria and the way to construct that can reveal essential aspects of the being of the things. The constructive process demands, in fact, the acquaintance of the formative properties of the matter. Property from which the reflections gush on the relations that can be born around the architecture through the resonance produced from the forms. The void, in fact, through the form is in a position to constructing the site establishing a reciprocity relation. A reciprocity that is determined in the game between empty and full and of the forms between each other, regarding around, but also with regard to the subjective experience. The construction of a background used to amplify what is arranged on it and to clearly show the relations between the parts and at the same time able to tie itself with around opening the space of the vision, is a system that in the architecture of Moneo has one of its more effective applications in the use of the platform used like architectonic element. The spiritual force of this architectonic gesture is in the ability to define a place whose projecting intention is perceived and shared with who experience and has lived like some instrument to contact the cosmic forces, in a delicate process that lead to the equilibrium with them, but in completely physical way. The principles subtended to the construction of the form taken from the study of the void and the relations that it concurs, lead to express human values in the construction of the site. The validity of these principles however is tested from the time. The time is what Moneo considers as filter that every architecture is subordinate to and the survival of architecture, or any of its formal characters, reveals them the validity of the principles that have determined it. It manifests thus, in the tie between the spatial and spiritual dimension, between the material and the worldly dimension, the state of necessity that leads, in the construction of the architecture, to establish a contact with the forces of the universe and the intimate world, through a process that translate that necessity in elaboration of a formal system.

Optische Spektroskopie an Fermium (Z=100)

Im Rahmen der vorliegenden Arbeit wurde erstmals Laser-Atomspektroskopie an einem Element durchgeführt, für das bisher keine atomaren Niveaus bekannt waren. Die Experimente wurden am Element Fermium mit der Ordnungszahl Z=100 mit der Resonanzionisationsspektroskopie (RIS) in einer Puffergaszelle durchgeführt. Verwendet wurde das Isotop 255Fm mit einer Halbwertszeit von 20.1 h, das im Hochflusskernreaktor des ORNL, Oak Ridge, USA, hergestellt wurde. Die von einem elektrochemischen Filament in das Argon-Puffergas bei einer Temperatur von 960(20)°C abgedampften Fm-Atome wurden mit Lasern in einem Zweistufenprozess resonant ionisiert. Dazu wurde das Licht eines Excimerlaser gepumpten Farbstofflasers für den ersten Anregungsschritt um die Wellenlänge 400 nm durchgestimmt. Ein Teil des Excimer (XeF) Laser Pumplichtes mit den Wellenlänge 351/353 nm wurde für die nicht-resonante Ionisation verwendet. Die Ionen wurden mit Hilfe elektrischer Felder aus der optischen Zelle extrahiert und nach einem Quadrupol Massenfilter mit einem Channeltron-Detektor massenselektiv nachgewiesen. Trotz der geringen Probenmenge von 2.7 x 10^10 eingesetzten Atomen wurden zwei atomare Resonanzen bei Energien von 25099.8(2) cm-1 und 25111.8(2) cm-1 gefunden und das Sättigungsverhalten dieser Linien gemessen. Es wurde ein theoretisches Modell entwickelt, dass sowohl das spektrale Profil der sättigungsverbreiterten Linien als auch die Sättigungskurven beschreibt. Durch Anpassung an die Messdaten konnten die partiellen Übergangsraten in den 3H6 Grundzustand Aki=3.6(7) x 10^6/s und Aki=3.6(6) x 10^6/s bestimmt werden. Der Vergleich der Niveauenergien und Übergangsraten mit Multikonfigurations Dirac-Fock Rechnungen legt die spektroskopische Klassifizierung der beobachteten Niveaus als 5f12 7s7p 5I6 und 5G6 Terme nahe. Weiterhin wurde ein Übergang bei 25740 cm-1 gefunden, der aufgrund der beobachteten Linienbreite von 1000 GHz als Rydbergzustand Zustand mit der Niveauenergie 51480 cm-1 interpretiert wurde und über einen Zweiphotonen Prozess angeregt werden kann. Basierend auf dieser Annahme wurde die Obergrenze für die Ionisationsenergie IP = 52140 cm-1 = 6.5 eV abgeschätzt. In den Messungen wurden Verschiebungen in den Zeitverteilungsspektren zwischen den mono-atomaren Ionen Fm+ und Cf+ und dem Molekül-Ion UO+ festgestellt und auf Driftzeitunterschiede im elektrischen Feld der gasgefüllten optischen Zelle zurückgeführt. Unter einfachen Modellannahmen wurde daraus auf die relativen Unterschiede Delta_r(Fm+,Cf+)/r(Cf+) ˜ -0.2 % und Delta_r(UO+,Cf+)/r(Cf+) ˜ 20 % in den Ionenradien geschlossen. Über die Bestimmung der Abnahme der Fm-a Aktivität des Filamentes auf der einen Seite und die Messung der Resonanzzählrate auf der anderen Seite, wurde die Nachweiseffizienz der Apparatur zu 4.5(3) x 10^-4 bestimmt. Die Nachweisapparatur wurde mit dem Ziel weiterentwickelt, Laserspektroskopie am Isotop 251Fm durchzuführen, das über die Reaktion 249Cf(a,2n)251Fm direkt in der optischen Zelle erzeugt werden soll. Das Verfahren wurde am chemischen Homolog Erbium getestet. Dabei wurde das Isotop 163Er über die Reaktion 161Dy(a,2n)163Er erzeugt und nach Resonanzionisation nachgewiesen. Die Nachweiseffizienz der Methode wurde zu 1 x 10^-4 bestimmt.

Mechanical microcontacts of powder particles studied with the quartz crystal microbalance

Within this work, a particle-polymer surface system is studied with respect to the particle-surface interactions. The latter are governed by micromechanics and are an important aspect for a wide range of industrial applications. Here, a new methodology is developed for understanding the adhesion process and measure the relevant forces, based on the quartz crystal microbalance, QCM. rnThe potential of the QCM technique for studying particle-surface interactions and reflect the adhesion process is evaluated by carrying out experiments with a custom-made setup, consisting of the QCM with a 160 nm thick film of polystyrene (PS) spin-coated onto the quartz and of glass particles, of different diameters (5-20µm), deposited onto the polymer surface. Shifts in the QCM resonance frequency are monitored as a function of the oscillation amplitude. The induced frequency shifts of the 3rd overtone are found to decrease or increase, depending on the particle-surface coupling type and the applied oscillation (frequency and amplitude). For strong coupling the 3rd harmonic decreased, corresponding to an “added mass” on the quartz surface. However, positive frequency shifts are observed in some cases and are attributed to weak-coupling between particle and surface. Higher overtones, i.e. the 5th and 7th, were utilized in order to derive additional information about the interactions taking place. For small particles, the shift for specific overtones can increase after annealing, while for large particle diameters annealing causes a negative frequency shift. The lower overtones correspond to a generally strong-coupling regime with mainly negative frequency shifts observed, while the 7th appears to be sensitive to the contact break-down and the recorded shifts are positive.rnDuring oscillation, the motion of the particles and the induced frequency shift of the QCM are governed by a balance between inertial forces and contact forces. The adherence of the particles can be increased by annealing the PS film at 150°C, which led to the formation of a PS meniscus. For the interpretation, the Hertz, Johnson-Kendall-Roberts, Derjaguin-Müller-Toporov and the Mindlin theory of partial slip are considered. The Mindlin approach is utilized to describe partial slip. When partial slip takes place induced by an oscillating load, a part of the contact ruptures. This results in a decrease of the effective contact stiffness. Additionally, there are long-term memory effects due to the consolidation which along with the QCM vibrations induce a coupling increase. However, the latter can also break the contact, lead to detachment and even surface damage and deformation due to inertia. For strong coupling the particles appear to move with the vibrations and simply act as added effective mass leading to a decrease of the resonance frequency, in agreement with the Sauerbrey equation that is commonly used to calculate the added mass on a QCM). When the system enters the weak-coupling regime the particles are not able to follow the fast movement of the QCM surface. Hence, they effectively act as adding a “spring” with an additional coupling constant and increase the resonance frequency. The frequency shift, however, is not a unique function of the coupling constant. Furthermore, the critical oscillation amplitude is determined, above which particle detach. No movement is detected at much lower amplitudes, while for intermediate values, lateral particle displacement is observed. rnIn order to validate the QCM results and study the particle effects on the surface, atomic force microscopy, AFM, is additionally utilized, to image surfaces and measure surface forces. By studying the surface of the polymer film after excitation and particle removal, AFM imaging helped in detecting three different meniscus types for the contact area: the “full contact”, the “asymmetrical” and a third one including a “homocentric smaller meniscus”. The different meniscus forms result in varying bond intensity between particles and polymer film, which could explain the deviation between number of particles per surface area measured by imaging and the values provided by the QCM - frequency shift analysis. The asymmetric and the homocentric contact types are suggested to be responsible for the positive frequency shifts observed for all three measured overtones, i.e. for the weak-coupling regime, while the “full contact” type resulted in a negative frequency shift, by effectively contributing to the mass increase of the quartz..rnThe interplay between inertia and contact forces for the particle-surface system leads to strong- or weak-coupling, with the particle affecting in three mentioned ways the polymer surface. This is manifested in the frequency shifts of the QCM system harmonics which are used to differentiate between the two interaction types and reflect the overall state of adhesion for particles of different size.rn

Spurenanalyse von Aktiniden in der Umwelt mittels Resonanzionisations-Massenspektrometrie

In dieser Arbeit wurde die Methode der resonanten Ionisation von neutralen Atomen mittels Laserstrahlung auf die leichten Aktinide Thorium, Uran, Neptunium und Plutonium angewendet und für die Ultraspurenanalyse optimiert. Der empfindliche Nachweis dieser Aktinide stellt eine Herausforderung für die Beobachtung und Bestimmung von radioaktiven Verunreinigungen aus kerntechnischen Anlagen in der Umwelt dar. In einem für diese Untersuchungen entwickelten Quadrupolmassenspektrometer konnte durch Resonanzionisationsspektroskopie jeweils eine Reihe unbekannter Energiezustände in der Elektronenhülle des neutralen Atoms der oben genannten Aktinide identifiziert, sowie effiziente Anregungsschemata für die resonante Ionisation entwickelt und charakterisiert werden. Durch die verwendete in-source-Ionisation, die aufgrund der guten Überlagerung von Laserstrahlung und Atomstrahl eine hohe Nachweiseffizienz gewährleistet, konnten diese Untersuchungen bereits mit einem, für Radionuklide notwendigen, geringen Probeneintrag erfolgen. Die resonante Ionisation erlaubt durch die selektiven resonanten Prozesse eine Unterdrückung unerwünschter Kontaminationen und wurde auf den analytischen Nachweis von Ultraspurengehalten in Umweltproben, sowie die Bestimmung der entsprechenden Isotopenzusammensetzung optimiert. Durch die effiziente in-source-Ionisation mit leistungsstarker gepulster Laserstrahlung, konnten Nachweiseffizienzen im Bereich von bis zu 1% erreicht werden. Dabei wurden für Plutonium in synthetischen Proben, aber auch in ersten Umweltproben, Nachweisgrenzen von 10^4-10^5 Atomen erzielt. Die Verwendung spektral schmalbandiger Dauerstrichlaser und eine Ionisation transversal zum frei propagierenden Atomstrahl ermöglicht durch Auflösung der Isotopieverschiebung eine hohe Selektivität gegenüber dominanten Nachbarisotopen, wohingegen die Ionisationseffizienz deutlich abnimmt. Hiermit konnte für das Ultraspurenisotop U-236 eine Nachweisgrenze bis hinab zu 10^-9 für das Isotopenverhältnis N(U-236)/N(U-238) bestimmt werden.

A Computational Model for Processing Lexical Information"

The group analysed some syntactic and phonological phenomena that presuppose the existence of interrelated components within the lexicon, which motivate the assumption that there are some sublexicons within the global lexicon of a speaker. This result is confirmed by experimental findings in neurolinguistics. Hungarian speaking agrammatic aphasics were tested in several ways, the results showing that the sublexicon of closed-class lexical items provides a highly automated complex device for processing surface sentence structure. Analysing Hungarian ellipsis data from a semantic-syntactic aspect, the group established that the lexicon is best conceived of being as split into at least two main sublexicons: the store of semantic-syntactic feature bundles and a separate store of sound forms. On this basis they proposed a format for representing open-class lexical items whose meanings are connected via certain semantic relations. They also proposed a new classification of verbs to account for the contribution of the aspectual reading of the sentence depending on the referential type of the argument, and a new account of the syntactic and semantic behaviour of aspectual prefixes. The partitioned sets of lexical items are sublexicons on phonological grounds. These sublexicons differ in terms of phonotactic grammaticality. The degrees of phonotactic grammaticality are tied up with the problem of psychological reality, of how many degrees of this native speakers are sensitive to. The group developed a hierarchical construction network as an extension of the original General Inheritance Network formalism and this framework was then used as a platform for the implementation of the grammar fragments.

Three-dimensional magnetic resonance observation of cartilage repair tissue (MOCART) score assessed with an isotropic three-dimensional true fast imaging with steady-state precession sequence at 3.0 Tesla

INTRODUCTION: Cartilage defects are common pathologies and surgical cartilage repair shows promising results. In its postoperative evaluation, the magnetic resonance observation of cartilage repair tissue (MOCART) score, using different variables to describe the constitution of the cartilage repair tissue and the surrounding structures, is widely used. High-field magnetic resonance imaging (MRI) and 3-dimensional (3D) isotropic sequences may combine ideal preconditions to enhance the diagnostic performance of cartilage imaging.Aim of this study was to introduce an improved 3D MOCART score using the possibilities of an isotropic 3D true fast imaging with steady-state precession (True-FISP) sequence in the postoperative evaluation of patients after matrix-associated autologous chondrocyte transplantation (MACT) as well as to compare the results to the conventional 2D MOCART score using standard MR sequences. MATERIAL AND METHODS: The study had approval by the local ethics commission. One hundred consecutive MR scans in 60 patients at standard follow-up intervals of 1, 3, 6, 12, 24, and 60 months after MACT of the knee joint were prospectively included. The mean follow-up interval of this cross-sectional evaluation was 21.4 +/- 20.6 months; the mean age of the patients was 35.8 +/- 9.4 years. MRI was performed at a 3.0 Tesla unit. All variables of the standard 2D MOCART score where part of the new 3D MOCART score. Furthermore, additional variables and options were included with the aims to use the capabilities of isotropic MRI, to include the results of recent studies, and to adapt to the needs of patients and physician in a clinical routine examination. A proton-density turbo spin-echo sequence, a T2-weighted dual fast spin-echo (dual-FSE) sequence, and a T1-weighted turbo inversion recovery magnitude (TIRM) sequence were used to assess the standard 2D MOCART score; an isotropic 3D-TrueFISP sequence was prepared to evaluate the new 3D MOCART score. All 9 variables of the 2D MOCART score were compared with the corresponding variables obtained by the 3D MOCART score using the Pearson correlation coefficient; additionally the subjective quality and possible artifacts of the MR sequences were analyzed. RESULTS: The correlation between the standard 2D MOCART score and the new 3D MOCART showed for the 8 variables "defect fill," "cartilage interface," "surface," "adhesions," "structure," "signal intensity," "subchondral lamina," and "effusion"-a highly significant (P < 0.001) correlation with a Pearson coefficient between 0.566 and 0.932. The variable "bone marrow edema" correlated significantly (P < 0.05; Pearson coefficient: 0.257). The subjective quality of the 3 standard MR sequences was comparable to the isotropic 3D-TrueFISP sequence. Artifacts were more frequently visible within the 3D-TrueFISP sequence. CONCLUSION: In the clinical routine follow-up after cartilage repair, the 3D MOCART score, assessed by only 1 high-resolution isotropic MR sequence, provides comparable information than the standard 2D MOCART score. Hence, the new 3D MOCART score has the potential to combine the information of the standard 2D MOCART score with the possible advantages of isotropic 3D MRI at high-field. A clear limitation of the 3D-TrueFISP sequence was the high number of artifacts. Future studies have to prove the clinical benefits of a 3D MOCART score.