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.

Utilizzo di dispositivi magnetici nel trattamento della patologia artrosica del ginocchio

The use of scaffolds for Tissue Engineering (TE) is increasing due to their efficacy in helping the body rebuild damaged or diseased tissue. Hydroxyapatite (HA) is the most suitable bioactive ceramic to be used in orthopaedic reconstruction since it replicates the mineral component of the hard tissues, and it has therefore excellent biocompatibility properties. The temporal and spatial control of the tissue regeneration process is the limit to be overcome in order to treat large bone and osteochondral defects. In this thesis we describe the realization of a magnetic scaffolds able to attract and take up growth factors or other bio-agents in vivo via a driving magnetic force. This concept involves the use of magnetic nanoparticles (MNP) functionalized with selected growth factors or stem cells. These functionalized MNP act as shuttles transporting the bio-agents towards and inside the scaffold under the effect of the magnetic field, enhancing the control of tissue regeneration processes. This scaffold can be imagined as a fixed “station” that provides a unique possibility to adjust the scaffold activity to the specific needs of the healing tissue. Synthetic bone graft substitutes, made of collagen or biomineralized collagen (i.e. biomimetic Hydroxyapatite/collagen composites) were used as starting materials for the fabrication of magnetic scaffolds. These materials are routinely used clinically to replace damaged or diseased cartilaginous or bone tissue. Our magnetization technique is based on a dip-coating process consisting in the infilling of biologically inspired porous scaffolds with aqueous biocompatible ferrofluids’ suspensions. In this technique, the specific interconnected porosity of the scaffolds allows the ferrofluids to be drawn inside the structure by capillarity. A subsequent freeze-drying process allows the solvent elimination while keeping very nearly the original shape and porosity of the scaffolds. The remaining magnetic nanoparticles, which are trapped in the structure, lead to the magnetization of the HA/Collagen scaffold. We demonstrate here the possibility to magnetize commercially available scaffolds up to magnetization values that are used in drug delivery processes. The preliminary biocompatibility test showed that the investigated scaffolds provide a suitable micro-environment for cells. The biocompatibility of scaffold facilitates the growth and proliferation of osteogenic cells.

Crescita volumetrica dei miomi uterini: analisi dei fattori di rischio

I miomi uterini sono la neoplasia uterina più comune e colpiscono fino al 30% delle donne in età fertile. Nonostante l’elevata prevalenza, pochi studi in Letteratura hanno analizzato i fattori di rischio per la crescita dei miomi uterini, mostrando spesso dei risultati contrastanti. Nel nostro studio osservazionale prospettico sono state arruolate pazienti che rispettassero i criteri di inclusione e di esclusione, con diagnosi di miomi uterini evidenziati mediante ecografia eseguita presso i nostri ambulatori, a partire da giugno 2017. A partire da gennaio 2019, sono state ricercate mensilmente le pazienti precedentemente arruolate che erano tornate presso i nostri ambulatori per esecuzione di ulteriore ecografia, a distanza di 24 ± 5 mesi, fino a raggiungere il campione designato, cioè 450 pazienti totali. È stato, quindi, valutato il tasso di crescita annuo del mioma di maggiori dimensioni ed è stato utilizzato l'approccio polinomiale frazionario multivariabile per selezionare i fattori di rischio anamnestici ed ecografici legati all’incremento volumetrico. Circa la metà dei miomi uterini analizzati ha mostrato stabilità dimensionale nel corso del follow-up (crescita ≤10%), mentre la restante metà ha mostrato una crescita > 10%. Il solo fattore di rischio associato alla crescita volumetrica dei miomi uterini è risultato essere il volume del mioma durante l’ecografia di arruolamento (P = 0.001), quindi miomi di piccole dimensioni presentano un tasso di crescita maggiore rispetto ai miomi di grandi dimensioni. Lo studio ha raccolto la più ampia casistica in Letteratura nella valutazione del naturale andamento di modifica dimensionale dei miomi uterini. Sebbene siano necessari ulteriori studi con campione più ampio, questi dati possono fornire un utile supporto per eseguire un adeguato counselling con le pazienti nella pratica clinica quotidiana.

Insulin and TOR pathways regulate cellular and organismal growth through the myc oncogene in Drosophila

A large body of literature documents in both mice and Drosophila the involvement of Insulin pathway in growth regulation, probably due to its role in glucose and lipid import, nutrient storage, and translation of RNAs implicated in ribosome biogenesis (Vanhaesebroeck et al. 2001). Moreover several lines of evidence implicate this pathway as a causal factor in cancer (Sale, 2008; Zeng and Yee 2007; Hursting et al., 2007; Chan et al., 2008). With regards to Myc, studies in cell culture have implied this family of transcription factors as regulators of the cell cycle that are rapidly induced in response to growth factors. Myc is a potent oncogene, rearranged and overexpressed in a wide range of human tumors and necessary during development. Its conditional knock-out in mice results in reduction of body weight due to defect in cell proliferation (Trumpp et al. 2001). Evidence from in vivo studies in Drosophila and mammals suggests a critical function for myc in cell growth regulation (Iritani and Eisenman 1999; Johnston et al. 1999; Kim et al. 2000; de Alboran et al. 2001; Douglas et al. 2001). This role is supported by our analysis of Myc target genes in Drosophila, which include genes involved in RNA binding, processing, ribosome biogenesis and nucleolar function (Orain et al 2003, Bellosta et al., 2005, Hulf et al, 2005). The fact that Insulin signaling and Myc have both been associated with growth control suggests that they may interact with each other. However, genetic evidence suggesting that Insulin signaling regulates Myc in vivo is lacking. In this work we were able to show, for the first time, a direct modulation of dMyc in response to Insulin stimulation/silencing both in vitro and in vivo. Our results suggest that dMyc up-regulation in response to DILPs signaling occurs both at the mRNA and potein level. We believe dMyc protein accumulation after Insulin signaling activation is conditioned to AKT-dependent GSK3β/sgg inactivation. In fact, we were able to demonstate that dMyc protein stabilization through phosphorylation is a conserved feature between Drosophila and vertebrates and requires multiple events. The final phosphorylation step, that results in a non-stable form of dMyc protein, ready to be degraded by the proteasome, is performed by GSK3β/sgg kinase (Sears, 2004). At the same time we demonstrated that CKI family of protein kinase are required to prime dMyc phosphorylation. DILPs and TOR/Nutrient signalings are known to communicate at several levels (Neufeld, 2003). For this reason we further investigated TOR contribution to dMyc-dependent growth regulation. dMyc protein accumulates in S2 cells after aminoacid stimulation, while its mRNA does not seem to be affected upon TORC1 inhibition, suggesting that the Nutrient pathway regulates dMyc mostly post-transcriptionally. In support to this hypothesis, we observed a TORC1-dependent GSK3β/sgg inactivation, further confirming a synergic effect of DILPs and Nutrients on dMyc protein stability. On the other hand, our data show that Rheb but not S6K, both downstream of the TOR kinase, contributes to the dMyc-induced growth of the eye tissue, suggesting that Rheb controls growth independently of S6K.. Moreover, Rheb seems to be able to regulate organ size during development inducing cell death, a mechanism no longer occurring in absence of dmyc. These observations suggest that Rheb might control growth through a new pathway independent of TOR/S6K but still dependent on dMyc. In order to dissect the mechanism of dMyc regulation in response to these events, we analyzed the relative contribution of Rheb, TOR and S6K to dMyc expression, biochemically in S2 cells and in vivo in morphogenetic clones and we further confirmed an interplay between Rheb and Myc that seems to be indipendent from TOR. In this work we clarified the mechanisms that stabilize dMyc protein in vitro and in vivo and we observed for the first time dMyc responsiveness to DILPs and TOR. At the same time, we discovered a new branch of the Nutrient pathway that appears to drive growth through dMyc but indipendently from TOR. We believe our work shed light on the mechanisms cells use to grow or restrain growth in presence/absence of growth promoting cues and for this reason it contributes to understand the physiology of growth control.

Il craniofaringioma nel bambino e nell'adolescente. Luci ed ombre durante il follow-up

Introduction. Craniopharyngioma (CF) is a malformation of the hypothalamicpituitary region and it is the most common nonglial cerebral tumor in children with an high overall survival rate. In some case severe endocrinologic and metabolic sequelae may occur during follow up. 50% of patients (pts), in particular those with radical removal of suprasellar lesions, develop intractable hyperphagia and morbid obesity, with dyslypidemia and high cardiovascular risk. We studied the auxological and metabolic features of a series of 29 patients (18 males) treated at a mean age of 7,6 years, followed up in our Centre from 1973 to 2008 with a mean follow up of 8,3 years. Patients features at the onset. 62% of pts showed as first symptoms of disease visual impairment and neurological disturbancies (headache); 34% growth arrest; 24% signs of raised intracranial pressure and 7% diabetes insipidus. Diagnosis. Diagnosis of CF was reached finally by TC or MRI scans which showed endo-suprasellar lesion in 23 cases and endosellar tumour in 6 cases. Treatment and outcome. 25/29 pts underwent surgical removal of CF (19 by transcranial approach and 6 by endoscopic surgery); 4 pts underwent stereotactic surgery as first line therapy. 3 pts underwent local irradiation with yttrium-90, 5 pts post surgery radiotherapy. 45% of pts needed more than one treatment procedure. Results. After CF treatment all patients suffered from 3 or more pituitary hormone deficiencies and diabetes insipidus. They underwent promptly substitutive therapy with corticosteroids, l-thyroxine and desmopressin. In 28/29 pts we found growth hormone (GH) deficiency. 20/28 pts started GH substitutive therapy and 15 pts reached final height(FH) near target height(TH). 8 pts were not GH treated for good growth velocity, even without GH, or for tumour residual. They reached in 2 cases FH over TH showing the already known phenomenon of growth without GH. 38% of patients showed BMI SDS >2 SDS at last assessment, in particular pts not GH treated (BMI 2,5 SDS) are more obese than GH treated (BMI 1,2 SDS). Lipid panel of 16 examined pts showed significative differencies among GH treated (9 pts) and not treated (7 pts) with better profile in GH treated ones for Total Cholesterol/C-HDL and C-LDL/C-HDL. We examined intima media thickness of common carotid arteries in 11 pts. 3/4 not GH treated pts showed ultrasonographic abnormalities: calcifications in 2 and plaque in 1 case. Of them 1 pt was only 12,6 years old and already showed hypothalamic obesity with hyperphagia, high HOMA index and dyslipidemia. In the GH treated group (7) we found calcifications in 1 case and a plaque in another one. GH therapy was started in the young pt with carotid calcifications, with good improvement within 6 months of treatment. 5/29 pts showed hypothalamic obesity, related to hypothalamic damage (type of surgical treatment, endo-suprasellar primitive lesion, recurrences). 48% of patients recurred during follow up ( mean time from treatment: 3 years) and underwent, in some cases up to 4 transcranial surgical treatments. GH seems not to increase recurrence rate since 40% of GH treated recurred vs 66,6% of not GH treated pts. Discussion. Our data show the extereme difficulties that occur during follow up of craniopharyngioma treated patients. GH therapy should be offered to all patients even with good growth velocity after CF treatment, to avoid dislypidemia and reduce cardiovascular risk. The optimal therapy is not completely understood and whether gross tumor removal or partial surgery is the best option remains to be decided only on one patient tumour features and hypothalamic involvement. In conclusion the gold standard treatment of CF remains complete tumour removal, when feasible, or partial resection to preserve hypothalamic function in endosuprasellar large neoplasms.

Advanced SPM studies on the growth of ultrathin films of organic semiconductors at metal and dielectric interfaces

Many studies on the morphology, molecular orientation, device performance, substrate nature and growth parameter dependence have been carried out since the proposal of Sexithiophene (6T) for organic electronics [ ] However, these studies were mostly performed on films thicker than 20nm and without specifically addressing the relationship between morphology and molecular orientation within the nano and micro structures of ultrathin films of 0-3 monolayers. In 2004, the observation that in OFETs only the first few monolayers at the interface in contact with the gate insulator contribute to the charge transport [ ], underlined the importance to study submonolayer films and their evolution up to a few monolayers of thickness with appropriate experimental techniques. We present here a detailed Non-contact Atomic Force Microscopy and Scanning Tunneling Microscopy study on various substrates aiming at the investigation of growth mechanisms. Most reported similar studies are performed on ideal metals in UHV. However it is important to investigate the details of organic film growth on less ideal and even technological surfaces and device testpatterns. The present work addresses the growth of ultra thin organic films in-situ and quasi real-time by NC-AFM. An organic effusion cell is installed to evaporate the organic material directly onto the SPM sample scanning stage.

Expression profiling in developing peach seed and mesocarp as affected by growth regulators

Jasmonates (JAs) and spermidine (Sd) influence fruit (and seed) development and ripening. In order to unravel their effects in peach fruit, at molecular level, field applications of methyl jasmonate (MJ) and propyl dihydrojasmonate (PDJ), and Sd were performed at an early developmental stage (late S1). At commercial harvest, JA-treated fruit were less ripe than controls. Realtime RT-PCR analyses confirmed a down-regulation of ethylene biosynthetic, perception and signaling genes, and flesh softening-related genes. The expression of cell wall-related genes, of a sugar-transporter and hormone-related transcript levels was also affected by JAs. Seeds from JA-treated fruit showed a shift in the expression of developmental marker genes suggesting that the developmental program was probably slowed down, in agreement with the contention that JAs divert resources from growth to defense. JAs also affected phenolic content and biosynthetic gene expression in the mesocarp. Levels of hydroxycinnamic acids, as well as those of flavan-3-ols, were enhanced, mainly by MJ, in S2. Transcript levels of phenylpropanoid pathway genes were up-regulated by MJ, in agreement with phenolic content. Sd-treated fruits at harvest showed reduced ethylene production and flesh softening. Sd induced a short-term and long-term response patterns in endogenous polyamines. At ripening the up-regulation of the ethylene biosynthetic genes was dramatically counteracted by Sd, leading to a down-regulation of softening-related genes. Hormone-related gene expression was also altered both in the short- and long-term. Gene expression analyses suggest that Sd interfered with fruit development/ripening by interacting with multiple hormonal pathways and that fruit developmental marker gene expression was shifted ahead in accord with a developmental slowing down. 24-Epibrassinolide was applied to Flaminia peaches under field conditions early (S1) or later (S3) during development. Preliminary results showed that, at harvest, treated fruit tended to be larger and less mature though quality parameters did not change relative to controls.

Integrated analysis and design of optimization and up-scaling of inductively coupled plasma synthesis of nanoparticles

This study is focused on radio-frequency inductively coupled thermal plasma (ICP) synthesis of nanoparticles, combining experimental and modelling approaches towards process optimization and industrial scale-up, in the framework of the FP7-NMP SIMBA European project (Scaling-up of ICP technology for continuous production of Metallic nanopowders for Battery Applications). First the state of the art of nanoparticle production through conventional and plasma routes is summarized, then results for the characterization of the plasma source and on the investigation of the nanoparticle synthesis phenomenon, aiming at highlighting fundamental process parameters while adopting a design oriented modelling approach, are presented. In particular, an energy balance of the torch and of the reaction chamber, employing a calorimetric method, is presented, while results for three- and two-dimensional modelling of an ICP system are compared with calorimetric and enthalpy probe measurements to validate the temperature field predicted by the model and used to characterize the ICP system under powder-free conditions. Moreover, results from the modeling of critical phases of ICP synthesis process, such as precursor evaporation, vapour conversion in nanoparticles and nanoparticle growth, are presented, with the aim of providing useful insights both for the design and optimization of the process and on the underlying physical phenomena. Indeed, precursor evaporation, one of the phases holding the highest impact on industrial feasibility of the process, is discussed; by employing models to describe particle trajectories and thermal histories, adapted from the ones originally developed for other plasma technologies or applications, such as DC non-transferred arc torches and powder spherodization, the evaporation of micro-sized Si solid precursor in a laboratory scale ICP system is investigated. Finally, a discussion on the role of thermo-fluid dynamic fields on nano-particle formation is presented, as well as a study on the effect of the reaction chamber geometry on produced nanoparticle characteristics and process yield.

Scaled down physical properties of semiconductor nanowires for nanoelectronics scaling up

Semiconductor nanowires (NWs) are one- or quasi one-dimensional systems whose physical properties are unique as compared to bulk materials because of their nanoscaled sizes. They bring together quantum world and semiconductor devices. NWs-based technologies may achieve an impact comparable to that of current microelectronic devices if new challenges will be faced. This thesis primarily focuses on two different, cutting-edge aspects of research over semiconductor NW arrays as pivotal components of NW-based devices. The first part deals with the characterization of electrically active defects in NWs. It has been elaborated the set-up of a general procedure which enables to employ Deep Level Transient Spectroscopy (DLTS) to probe NW arrays’ defects. This procedure has been applied to perform the characterization of a specific system, i.e. Reactive Ion Etched (RIE) silicon NW arrays-based Schottky barrier diodes. This study has allowed to shed light over how and if growth conditions introduce defects in RIE processed silicon NWs. The second part of this thesis concerns the bowing induced by electron beam and the subsequent clustering of gallium arsenide NWs. After a justified rejection of the mechanisms previously reported in literature, an original interpretation of the electron beam induced bending has been illustrated. Moreover, this thesis has successfully interpreted the formation of NW clusters in the framework of the lateral collapse of fibrillar structures. These latter are both idealized models and actual artificial structures used to study and to mimic the adhesion properties of natural surfaces in lizards and insects (Gecko effect). Our conclusion are that mechanical and surface properties of the NWs, together with the geometry of the NW arrays, play a key role in their post-growth alignment. The same parameters open, then, to the benign possibility of locally engineering NW arrays in micro- and macro-templates.

Interfacial interactions, charge transport and growth phenomena in Organic Field Effect Transistors

Organic electronics is an emerging field with a vast number of applications having high potential for commercial success. Although an enormous progress has been made in this research area, many organic electronic applications such as organic opto-electronic devices, organic field effect transistors and organic bioelectronic devices still require further optimization to fulfill the requirements for successful commercialization. The main bottle neck that hinders large scale production of these devices is their performances and stability. The performance of the organic devices largely depends on the charge transport processes occurring at the interfaces of various material that it is composed of. As a result, the key ingredient needed for a successful improvement in the performance and stability of organic electronic devices is an in-depth knowledge of the interfacial interactions and the charge transport phenomena taking place at different interfaces. The aim of this thesis is to address the role of the various interfaces between different material in determining the charge transport properties of organic devices. In this framework, I chose an Organic Field Effect Transistor (OFET) as a model system to carry out this study as it An OFET offers various interfaces that can be investigated as it is made up of stacked layers of various material. In order to probe the intrinsic properties that governs the charge transport, we have to be able to carry out thorough investigation of the interactions taking place down at the accumulation layer thickness. However, since organic materials are highly instable in ambient conditions, it becomes quite impossible to investigate the intrinsic properties of the material without the influence of extrinsic factors like air, moisture and light. For this reason, I have employed a technique called the in situ real-time electrical characterization technique which enables electrical characterization of the OFET during the growth of the semiconductor.

Obscured AGN in deep fields: tracing accretion and star-formation up to z ∼ 5

The discovery of scaling relations between the mass of the SMBH and some key physical properties of the host galaxy suggests that the growth of the SMBH and that of the galaxy are coupled, with the AGN activity and the star-formation (SF) processes influencing each other. Although the mechanism of this co-evolution are still a matter of debate, all scenarios agree that a key phase of the co-evolution is represented by the obscured accretion phase. This phase is of the co-evolution is the least studied, mostly due to the challenge in detecting and recognizing such obscured AGN. My thesis aims at investigating the AGN-galaxy co-evolution paradigm by identifying and studying AGN in the obscured accretion phase. The study of obscured AGN is key for our understanding of the feedback processes and of the mutual influence of the SF and the AGN activity. Moreover, these obscured and elusive AGN are needed to explain the X-ray background spectrum and to reconcile the measurements and the theoretical prediction of the BH accretion rate density. In this thesis, we firstly investigate the synergies between IR and X-ray missions in detecting and characterizing AGN, with a particular focus on the most obscured ones. We exploited UV/optical emission lines to select high-redshift obscured AGN at the cosmic noon, where the highest SFR density and BH accretion rate density are expected. We provide X-ray spectral analysis and UV-to-far-IR SED-fitting. We show that our samples host a significant fraction of very obscured sources; many of these are highly accreting. Finally, we performe a thoughtful investigation of a galaxy at z~5 with unusual and peculiar features, that lead us to identify a second extremely young population of stars and hidden AGN activity.