Towards magnetic engineering at metal surfaces

The aim of this thesis is twofold: on the one hand to demonstrate a new method of building magnetic nanostructures at surfaces and on the other hand to present the construction of a new 1K UHV Low Temperature STM aimed at coupling the spatial resolution of the STM microscope with the capability to detect magnetism. The focus of the first chapter is the construction of the entire system incorporating the STM microscope. Design and the functionalities of the instrument are emphasized. The system is an Eigler type UHV LT STM. This class of low T STM relies on a pendulum mechanism which mechanically decouples the STM from the entire UHV system. As a result the mechanical stability of the microscope is particularly improved. Besides, this design will allow eventually to develop a temperature control allowing the instrument to work between 1 and 80 K. Unlike the first generation of Eigler type STM, the temperature can be lowered below 4.2 K by the use of a Joule-Thompson expansion closed cycle. He3 is let to expand into the cavity allocating the pendulum. Upon circulation of the gas around the pendulum the microscope is cooled down to a temperature as low as 0.5 K. The STM microscope itself is adapted from a design originally proposed by Pan and then developed by Pietzch. This design is compact, stable, provides a good thermal stability and allows for in situ 180° sample rotation. Different proposals for the detection of magnetism with the STM are described at the end of the chapter. The second chapter is inherently focused on the construction of magnetic nanostructures at surfaces under UHV conditions. A VT-STM is used to characterize organo-metallic assemblies formed on Cu(100). A magnetic atom, Fe, and an organic molecule, TMA, are deposited on the surface. A chemical reaction between the two adsorbates takes place. The TMA molecules offers three carboxyl moieties for lateral linkage to the Fe atoms. In this respect the coordinative interaction between the carboxyl moiety and the Fe atom can be suitably used to build a range of different nano structures. By tuning the reciprocal amount of ligand [L] and metal [M] i.e. [M]/[L], the sequence of adsorbates deposition, the substrate temperature, a number of different structures can be synthesized. At low values of [M]/[L] mononuclear Fe[TMA]4 complexes evolve. These complexes are chiral. For increasing values [M]/[L] multiple linkage of TMA molecules is observed. By inverting the order of adsorbates deposition polynuclear complexes are observed at flat terraces. Upon annealing the formation of 1D and 2D structures arises. The 2D assemblies comprise chiral arrangements of 1D structures. The 2D assemblies may result from an hierarchical effect of chemical interactions within and among 1D structures, i.e. coordinative bonding and hydrogen bonding. Unlike crystal engineering the adsorbate-substrate interaction still plays a relevant role in this scenario. A thorough discussion of the possible applications of this technique to reproduce results of magneto chemistry is also presented

A Short-Period Therapy with Subcutaneous Low-Dose IL-2 Plus High-Dose Melatonin to Correct Advanced Cancer-Related Lymphocytopenia: Possible Impact on the Survival Time

n/

EMT/MET at the crossroad of stemness, regeneration and oncogenesis. The Ying-Yang equilibrium recapitulated in cell spheroids

The epithelial-to-mesenchymal transition (EMT) is an essential trans-differentiation process, which plays a critical role in embryonic development, wound healing, tissue regeneration, organ fibrosis, and cancer progression. It is the fundamental mechanism by which epithelial cells lose many of their characteristics while acquiring features typical of mesenchymal cells, such as migratory capacity and invasiveness. Depending on the contest, EMT is complemented and balanced by the reverse process, the mesenchymal-to-epithelial transition (MET). In the saving economy of the living organisms, the same (Ying-Yang) tool is integrated as a physiological strategy in embryonic development, as well as in the course of reparative or disease processes, prominently fibrosis, tumor invasion and metastasis. These mechanisms and their related signaling (e.g., TGF-β and BMPs) have been effectively studied in vitro by tissue-derived cell spheroids models. These three-dimensional (3D) cell culture systems, whose phenotype has been shown to be strongly dependent on TGF-β-regulated EMT/MET processes, present the advantage of recapitulating in vitro the hypoxic in vivo micro-environment of tissue stem cell niches and their formation. These spheroids, therefore, nicely reproduce the finely regulated Ying-Yang equilibrium, which, together with other mechanisms, can be determinant in cell fate decisions in many pathophysiological scenarios, such as differentiation, fibrosis, regeneration, and oncogenesis. In this review, current progress in the knowledge of signaling pathways affecting EMT/MET and stemness regulation will be outlined by comparing data obtained from cellular spheroids systems, as ex vivo niches of stem cells derived from normal and tumoral tissues. The mechanistic correspondence in vivo and the possible pharmacological perspective will be also explored, focusing especially on the TGF-β-related networks, as well as others, such as SNAI1, PTEN, and EGR1. This latter, in particular, for its ability to convey multiple types of stimuli into relevant changes of the cell transcriptional program, can be regarded as a heterogeneous "stress-sensor" for EMT-related inducers (growth factor, hypoxia, mechano-stress), and thus as a therapeutic target

A quantum particle in a box with moving walls

We analyze the non-relativistic problem of a quantum particle that bounces back and forth between two moving walls. We recast this problem into the equivalent one of a quantum particle in a fixed box whose dynamics is governed by an appropriate time-dependent Schroedinger operator.Comment: 12 pages, 0 figure

Rilievi e indagini diagnostiche non distruttive per l’individuazione delle cripte - La Cattedrale di Ragusa

I diversi operatori, che si occupano di Beni Storici e Culturali, si avvalgono sempre più spesso delle soluzioni tecnologiche avanzate offerte dalla moderna Geomatica, facendo ricorso ad integrazioni delle sue discipline, per meglio studiare, indagare e monitorare un bene di interesse storico. Oggi si tentano nuove integrazioni con altre discipline che, tradizionalmente, non riguardano il campo del rilievo propriamente detto. Questo è, ad esempio, il caso dello studio condotto sulla Cattedrale di San Giovanni a Ragusa, nel quale si è partiti dal rilievo laser scanning di una porzione della chiesa e del suo pregiatissimo pavimento, sotto il quale secondo uno schizzo dei primi anni del XIX secolo (Fig. 1) dovrebbero trovarsi delle sepolture, per poi proseguire lo studio con l’ausilio del Georadar, strumento utilizzato tradizionalmente da geofisici e geologi per indagare il terreno. Ciò è stato fatto al fine di verificare l’effettiva presenza di strutture ipogee senza però agire con indagini invasive. Il risultato dell’elaborazione dei dati georadar, trasformato in una ricostruzione tridimensionale del sottopavimento, è stato affiancato alla ricostruzione tridimensionale della chiesa, realizzata dall’elaborazione dei dati del rilievo laser scanning. Tale integrazione ha permesso di confermare la presenza di strutture ipogee e di capire in che relazione sono queste ultime con gli avvallamenti presenti nel pavimento della chiesa. Del modello tridimensionale completo si è, infine, realizzata una versione navigabile (VRML), capace di offrire una visualizzazione e un’interazione anche ad utenti privi di conoscenze informatiche approfondite

Turin : une BM internationale pour 2006

Le 23 mars 2001, un jury international composé d’architectes, d’ingénieurs, de bibliothécaires et d’experts de théâtre a déclaré l’architecte Mario Bellini vainqueur du concours international lancé par la ville de Turin pour le projet d’un centre culturel comprenant la nouvelle bibliothèque municipale centrale. L’achèvement du projet définitif est prévu pour 2003 et la construction sera achevée fin 2006, début 2007

Effect of efflux pump inhibition on Pseudomonas aeruginosa transcriptome and virulence

Efflux pumps of the resistance-nodulation-cell-division (RND) family increase antibiotic resistance in many bacterial pathogens, representing candidate targets for the development of antibiotic adjuvants. RND pumps have also been proposed to contribute to bacterial infection, implying that efflux pump inhibitors (EPIs) could also act as anti-virulence drugs. Nevertheless, EPIs are usually investigated only for their properties as antibiotic adjuvants, while their potential anti-virulence activity is seldom taken into account. In this study it is shown that RND efflux pumps contribute to Pseudomonas aeruginosa PAO1 pathogenicity in an insect model of infection, and that the well-characterized EPI Phe-Arg-β-naphthylamide (PAβN) is able to reduce in vivo virulence of the P. aeruginosa PAO1 laboratory strain, as well as of clinical isolates. The production of quorum sensing (QS) molecules and of QS-dependent virulence phenotypes is differentially affected by PAβN, depending on the strain. Transcriptomic and phenotypic analyses showed that the protection exerted by PAβN from P. aeruginosa PAO1 infection in vivo correlates with the down-regulation of key virulence genes (e.g. genes involved in iron and phosphate starvation). Since PAβN impacts P. aeruginosa virulence, anti-virulence properties of EPIs are worthy to be explored, taking into account possible strain-specificity of their activit

Extended endoscopic endonasal transsphenoidal approach to the suprasellar area: Anatomic considerations - Part I

INTRODUCTION: Interest in using the extended endonasal transsphenoidal approach for management of suprasellar lesions, with either a microscopic or endoscopic technique, has increased in recent years. The most relevant benefit is that this median approach permits the exposure and removal of suprasellar lesions without the need for brain retraction. MATERIALS AND METHODS: Fifteen human cadaver heads were dissected to evaluate the surgical key steps and the advantages and limitations of the extended endoscopic endonasal transplanum sphenoidale approach. We compared this with the transcranial microsurgical view of the suprasellar area as explored using the bilateral subfrontal microsurgical approach, and with the anatomy of the same region as obtained through the endoscopic endonasal route. RESULTS: Some anatomic conditions can prevent or hinder use of the extended endonasal approach. These include a low level of sphenoid sinus pneumatization, a small sella size with small distance between the internal carotid arteries, a wide intercavernous sinus, and a thick tuberculum sellae. Compared with the subfrontal transcranial approach, the endoscopic endonasal approach offers advantages to visualizing the subchiasmatic, retrosellar, and third ventricle areas. CONCLUSION: The endoscopic endonasal transplanum sphenoidale technique is a straight, median approach to the midline areas around the sella that provides a multiangled, close-up view of all relevant neurovascular structures. Although a lack of adequate instrumentation makes it impossible to manage all structures that are visible with the endoscope, in selected cases, the extended endoscopic endonasal approach can be considered part of the armamentarium for surgical treatment of the suprasellar area