Ultra-High Q-Factor Silicon Resonator for High Frequency Oscillators

The thesis focuses on the investigation and characterisation of ultra-high Q-factor low loss Silicon resonators with transverse electric (TE)-like electromagnetic band-gap determined by two dimensional periodic structure made of a Silicon slab having a triangular lattice of air cylinders. A band-gap is observed where no energy is propagated through the slab, however engineering defects are created and optimised within the lattice producing resonant cavities and waveguides. The structure being excited with the fundamental TE10 mode can be coupled to external circuits via waveguides and its respective transitions in co-planar waveguide transmission line used to convey the millimetre-wave frequency signals. The ultimate goal is to investigate and characterise the promising low loss and high frequency Silicon resonators suitable for millimetre-wave communications such as used in low phase noise oscillator application and band pass filters. The results clearly show that electromagnetic band-gap structures or photonic crystals (PC) can be utilized for application in high frequency oscillators directly in fundamental mode with great benefits in obtaining ultra-high Q-factor and therefore low phase noise; and with better performance than alternative state-of-art technologies such as crystal oscillators in combination with frequency multiplication or frequency synthesis causing an increase in the overall phase noise by 20 log rule. By successfully demonstrating the experiment of using electromagnetic band-gap structures with oscillators, it is a great contribution towards the solution of the problem of high phase noise affecting high frequency oscillators operating at millimetre-wave band

An X-ray variable absorber within the Broad Line Region in Fairall 51

Fairall 51 is a polar-scattered Seyfert 1 galaxy, a type of active galaxies believed to represent a bridge between unobscured type-1 and obscured type-2 objects. Fairall 51 has shown complex and variable X-ray absorption but only little is known about its origin. In our research, we observed Fairall 51 with the X-ray satellite Suzaku in order to constrain a characteristic time-scale of its variability. We performed timing and spectral analysis of four observations separated by 1.5, 2 and 5.5 day intervals. We found that the 0.5-50 keV broadband X-ray spectra are dominated by a primary power-law emission (with the photon index ~ 2). This emission is affected by at least three absorbers with different ionisations (log(xi) ~ 1-4). The spectrum is further shaped by a reprocessed emission, possibly coming from two regions -- the accretion disc and a more distant scattering region. The accretion disc emission is smeared by the relativistic effects, from which we measured the spin of the black hole as a ~ 0.8 (+-0.2). We found that most of the spectral variability can be attributed to the least ionised absorber whose column density changed by a factor of two between the first (highest-flux) and the last (lowest-flux) observation. A week-long scale of the variability indicates that the absorber is located at the distance ~ 0.05 pc from the centre, i.e., in the Broad Line Region.Comment: 12 pages, 9 figures, accepted to A&

Adhesion and proliferation of human schwann cells on adhesive coatings

Attachment to and proliferation on the substrate are deemed important considerations when Schwann cells (SCs) are to be seeded in synthetic nerve grafts. Attachment is a prerequisite for the SCs to survive and fast proliferation will yield large numbers of SCs in a short time, which appears promising for stimulation of peripheral nerve regeneration. The aim of the present study was to compare the adhesion and proliferation of human Schwann cells (HSCs) on different substrates. The following were selected for their suitability as an internal coating of synthetic nerve grafts; the extracellular matrix proteins fibronectin, laminin and collagen type I and the poly-electrolytes poly( -lysine) (PDL) and poly(ethylene-imine) (PEI). On all coatings, attachment of HSCs was satisfactory and comparable, indicating that this factor is not a major consideration in choosing a suitable coating.\ud \ud Proliferation was best on fibronectin, laminin and PDL, and worst on collagen type I and PEI. Since nerve regeneration is enhanced by laminin and/or fibronectin, these are preferred as coatings for synthetic nerve grafts seeded with SCs

366. Development of Engineered Magnetic Nanoparticles Coupled With Lentiviral Vectors for Targeted Cancer Therapy and Hyperthermia

BackgroundIn recent years, considerable efforts have been spent to develop magnetic nanoparticles (MNPs) and to improve their applicability in several areas including hyperthermia and target cancer gene therapies.The aim of the present study was to synthesize and characterize Fe3O4, magnetite core-silica shell and magnetite core-silica shell doped with calcium ions nanoparticles (NPs) in combination with lentiviral vectors to deliver therapeutic genes in vivo.Materials and MethodsMagnetite NPs were prepared by co-precipitation method, the silica shell was obtained by wet chemistry on the magnetic core stabilized with citric acid. Calcium ions were added to the silica shell modulating the NPs surface reactivity.The NPs were characterized with X-Ray diffraction, transmission electron microscopy, Vibrating Sample Magnetometer and zeta potential.Cytocompatibility tests were performed using both direct and not-direct contact models with murine endothelial cells (MS1) both in static and dynamic conditions using MNP coupled with/out LV.MNP and MNP-LV were tail vein injected intravenously in C57/Bl6 mice, biodistribution and expression studies were performed by histology and immunofluorescence using GFP as a marker gene.ResultsSpherical magnetite nanoparticles of about 15 nm in diameter were obtained with good dispersion in water. Addition of silica and calcium allowed obtaining a thin and amorphous silica or Ca-enriched silica shell, maintaining good dispersion in water. All the MNPs displayed a superparamagnetic behaviour.The MNP+/-LV used demonstrated to be cytocompatible in both static traditional and dynamic cytocompatibility models. Moreover when MNP-LV injected in mice we detected GFP expression mainly in the liver and spleen with biodistribution differences based on the MNPs-LV combination used.ConclusionThese results suggest these NPs as promising for in vivo applications. Biodistribution studies in vivo of Fe3O4 NPs in mice models were performed and accumulation of NPs into vital organs was minimal with no toxicity in mice up to 1 month later and sustained GFP expression detected with no inflammatory responses. The present studies can significantly improve the cancer therapy effectiveness by means of a selective and localized delivery of transgenes together with the opportunity to conjugate hyperthermic and genetic approaches using therapeutic transgenes

Description of a Sarcoptic Mange Outbreak in Alpine Chamois Using an Enhanced Surveillance Approach

Since 1995, the Alpine chamois (Rupicapra r. rupicapra) population of the Dolomites has been affected by sarcoptic mange with considerable management concerns. In this study, 15 years (2006–2020) of passive surveillance and demographic data were analyzed in order to describe a mange outbreak. Furthermore, an enhanced passive surveillance protocol was implemented in order to evaluate the efficiency of ordinary vs. enhanced surveillance protocol in identifying dead chamois in the field and in reaching a correct diagnosis. Our results confirm the role of mange as a determining factor for chamois mortality, while stressing the importance of a wider view on the factors affecting population dynamics. The enhanced passive surveillance protocol increased the probability of carcass retrieval and identification of the cause of death; however, its adoption may be too costly if applied for long periods on a wide scale. Passive surveillance, in both ordinary and enhanced surveillance protocol, should encompass the use of other strategies in the future to study the eco-epidemiology of the disease in wild Caprinae

Biomarkers of Acute Graft-Versus-Host Disease: Surface Antigens and Micro Rnas in Extracellular Vesicles

Introduction Biomarkers could be crucial to identify patients at high-risk of acute Graft-vs.-Host Disease (aGVHD). Given their involvement in inflammation, Extracellular Vesicles (EVs) may become attractive biomarkers. Moreover, EVs are non-invasively extracted from body fluids. In a preliminary study, we significantly correlated CD146, CD31 and CD140a expression on EVs membranes with the onset of aGVHD (Lia G. Leukemia 2017). Objectives We designed a prospective study to further characterize EVs by their surface antigens and by their content in MicroRNAs. Methods EVs are extracted from serum samples at given time-points (pre-transplant, on day 0, 3, 7, 14, 21, 28, 35, 45 and then monthly up to 1 year) by a protamine-based precipitation method and analyzed by flow-cytometry (Guava EasyCyte Flow Cytometer) for the expression of 13 membrane proteins (CD44, CD138, CD146, KRT18, CD120a, CD8, CD30, CD106, CD25, CD31, CD144, CD86, and CD140a). MicroRNAs (miR100, miR92b, miR155, miR194) are extracted from EVs at pre- transplant and on day 0, 7, 14, 28, and quantified by real time PCR as relative quantification compared to healthy donors after cDNA Reverse Transcription. Logistic Regression Analysis is performed for each marker. Results Thirty-five transplant patients with hematological diseases have so far been enrolled. Seventeen/35 patients (49%) developed grade II-IV aGVHD. Our preliminary findings show that CD146 (melanoma cell adhesion molecule, MCAM-1) and CD44 (homing-associated cell adhesion molecule, H-CAM) were associated with an increased risk of aGVHD (Odds Ratio (OR) 4.3, p=0.008; OR 2.1, p=0.039), whereas CD31 (platelet endothelial cell adhesion molecule, PECAM-1) level was associated with a decreased risk of aGVHD (OR 0.31, p=0.001). Moreover, increased risk of aGVHD was significantly correlated with levels of miR100 (OR 4.66, p=0.004), miR194 (OR 2.2, p=0.01) and miR155 (OR 3.56, p=0.035). Of note, biomarkers associated with aGVHD showed a constant consensual change in signal levels before aGVHD onset (Figure 1). Conclusions An association of 3 EVs membrane antigens and onset of aGVHD was observed. Of note, CD146, CD44 and CD31 belong to the Cell Adhesion Molecule Family and are critical for endothelium and immune cells interactions. The functional role of miR-194 in GVHD pathogenesis remains to be determined while JAK/STAT and TGFβ pathways were shown to be involved in other studies (Gimondi S Exp Hematol, 2016). MiR-100 has been reported to regulate inflammatory neovascularization during GvHD (Leonhardt F, Blood 2013) while miR-155 drives donor T cell expansion and tissue infiltration (Zitzer N, J Immunol 2018, Ranganathan P Blood 2012)