Cristalli fotonici monodimensionali nanostrutturati per applicazioni sensoristiche

I cristalli fotonici, strutture costituite da una disposizione periodica di materiali a diverso indice di rifrazione in una o più dimensioni dello spazio, sono materiali caratterizzati da spettri di riflettività in cui sono presenti intervalli di lunghezze d'onda a riflettività idealmente unitaria. Un materiale tra i più promettenti, efficaci ed economici per la produzione di cristalli fotonici è il silicio poroso. L'impiego del silicio poroso nella produzione di cristalli fotonici è molto interessante dal punto di vista sensoristico; infatti, se l'aria presente nella struttura porosa viene sostituita da un liquido con dato indice di rifrazione o con materiale biologico le proprietà ottiche del cristallo fotonico risulteranno mutate. Il silicio poroso può essere prodotto mediante un processo controllato di erosione elettrochimica in soluzioni acquose contenti acido fluoridrico (HF). In particolare, il silicio poroso esibisce proprietà ottiche che dipendono dalla morfologia (porosità, spessore dello strato poroso) della sua struttura. Nel presente lavoro di tesi, è stata sfruttata la possibilità di modulare la porosità del silicio poroso prodotto mediante erosione elettrochimica, per fabbricare una particolare tipologia di cristalli fotonici: i “rugate filter”. Tali strutture presentano un profilo di porosità e, quindi, di indice di rifrazione, di tipo sinusoidale in una direzione dello spazio (direzione ortogonale alla superficie del wafer di silicio in cui il rugate filter è realizzato). Dal punto di vista ottico tali strutture esibiscono degli spettri di riflettività con un picco centrato ad una ben precisa lunghezza d'onda. L’obiettivo principale del presente lavoro di tesi è stato quello di progettare, fabbricare e caratterizzare otticamente rugate filter, realizzati in silicio poroso nanostrutturato operanti nel visibile (350 nm – 780 nm). A partire dagli spettri di riflessione sono state ricavate le proprietà di tali filtri ottici: banda spettrale, lunghezza d'onda a centro banda e fattore di qualità. Tale studio ha rappresentato la prima tappa verso lo sviluppo di un (bio)sensore di tipo ottico. In particolare, tale possibilità è stata investigata preliminarmente mediante uno studio di tipo optofluidico che ha previsto l'acquisizione degli spettri di riflettività dei rugate filter fabbricati in presenza di liquidi, a diverso indice di rifrazione infiltrati per capillarità all’interno dei pori. In particolare, monitorando lo spostamento del picco di riflettività in funzione dell'indice di rifrazione del liquido all'interno dei pori, è stato possibile stimare due parametri molto importanti in ambito sensoristico: la Sensitivity ed il Limit-of-Detection. I risultati ottenuti sono confrontabili con lo stato dell'arte di questa tecnologia, specialmente per quanto riguarda la Sensitivity il cui valore è dell'ordine di qualche centinaio di nanometri per variazione unitaria di indice di rifrazione. Sebbene non ancora ottimizzati, i rugate filter fabbricati durante l'attività sperimentale del presente lavoro di tesi risultano promettenti nella realizzazione di (bio)sensori di tipo ottico

Serum BAFF levels, methypredsinolone therapy, Epstein-Barr virus and <i>Mycobacterium avium</i> subsp. <i>paratuberculosis</i> infection in Multiple Sclerosis patients

Elevated B lymphocyte activating factor BAFF levels have been reported in multiple sclerosis (MS) patients; moreover, disease-modifying treatments (DMT) have shown to influence blood BAFF levels in MS patients, although the significance of these changes is still controversial. In addition, BAFF levels were reported increased during infectious diseases. In our study, we wanted to investigate on the serum BAFF concentrations correlated to the antibody response against Mycobacterium avium subspecies paratuberculosis (MAP), Epstein-Barr virus (EBV) and their human homologous epitopes in MS and in patients affected with other neurological diseases (OND), divided in Inflammatory Neurological Diseases (IND), Non Inflammatory Neurological Diseases (NIND) and Undetermined Neurological Diseases (UND), in comparison to healthy controls (HCs). Our results confirmed a statistically significant high BAFF levels in MS and IND patients in comparison to HCs but not NIND and UND patients. Interestingly, BAFF levels were inversely proportional to antibodies level against EBV and MAP peptides and the BAFF levels significantly decreased in MS patients after methylprednisolone therapy. These results implicate that lower circulating BAFF concentrations were present in MS patients with humoral response against MAP and EBV. In conclusion MS patients with no IgGs against EBV and MAP may support the hypothesis that elevated blood BAFF levels could be associated with a more stable disease

Type 1 Diabetes at-risk children highly recognize <i>Mycobacterium avium</i> subspecies <i>paratuberculosis</i> epitopes homologous to human Znt8 and Proinsulin

Mycobacterium avium subspecies paratuberculosis (MAP) has been previously associated to T1D as a putative environmental agent triggering or accelerating the disease in Sardinian and Italian populations. Our aim was to investigate the role of MAP in T1D development by evaluating levels of antibodies directed against MAP epitopes and their human homologs corresponding to ZnT8 and proinsulin (PI) in 54 T1D at-risk children from mainland Italy and 42 healthy controls (HCs). A higher prevalence was detected for MAP/ZnT8 pairs (62,96% T1D vs. 7,14% HCs; p &lt; 0.0001) compared to MAP/PI epitopes (22,22% T1D vs. 9,52% HCs) and decreasing trends were observed upon time-point analyses for most peptides. Similarly, classical ZnT8 Abs and GADA decreased in a time-dependent manner, whereas IAA titers increased by 12%. Responses in 0–9 year-old children were stronger than in 10–18 age group (75% vs. 69,1%; p &lt; 0.04). Younger age, female sex and concomitant autoimmune disorders contributed to a stronger seroreactivity suggesting a possible implication of MAP in multiple autoimmune syndrome. Cross-reactivity of the homologous epitopes was reflected by a high correlation coefficient (r2 &gt; 0.8) and a pairwise overlap of positivity (&gt;83% for MAP/ZnT8)

Inflammation, Infectious Triggers, and Parkinson's Disease

Parkinson's disease is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons of the substantia nigra pars compacta with a reduction of dopamine concentration in the striatum. The complex interaction between genetic and environmental factors seems to play a role in determining susceptibility to PD and may explain the heterogeneity observed in clinical presentations. The exact etiology is not yet clear, but different possible causes have been identified. Inflammation has been increasingly studied as part of the pathophysiology of neurodegenerative diseases, corroborating the hypothesis that the immune system may be the nexus between environmental and genetic factors, and the abnormal immune function can lead to disease. In this review we report the different aspects of inflammation and immune system in Parkinson's disease, with particular interest in the possible role played by immune dysfunctions in PD, with focus on autoimmunity and processes involving infectious agents as a trigger and alpha-synuclein protein (α-syn)

Deciphering Molecular Mechanisms of Interface Buildup and Stability in Porous Si/Eumelanin Hybrids

Porous Si/eumelanin hybrids are a novel class of organic–inorganic hybrid materials that hold considerable promise for photovoltaic applications. Current progress toward device setup is, however, hindered by photocurrent stability issues, which require a detailed understanding of the mechanisms underlying the buildup and consolidation of the eumelanin–silicon interface. Herein we report an integrated experimental and computational study aimed at probing interface stability via surface modification and eumelanin manipulation, and at modeling the organic–inorganic interface via formation of a 5,6-dihydroxyindole (DHI) tetramer and its adhesion to silicon. The results indicated that mild silicon oxidation increases photocurrent stability via enhancement of the DHI–surface interaction, and that higher oxidation states in DHI oligomers create more favorable conditions for the efficient adhesion of growing eumelanin

Inhibition of Listeria monocytogenes by a formulation of selected dairy starter cultures and probiotics in an in vitro model

Three strains of lactic acid bacteria (LAB) and a commercial probiotic were selected to evaluate their in vitro activity towards Listeria monocytogenes. The strains Lactococcus lactis ssp. lactis, strain 340, L. lactis ssp. lactis, strain 16; Lactobacillus casei ssp. casei, strain 208 and Enterococcus faecium UBEF-41 were inoculated into skim milk and brain heart infusion broth (BHI) to get an initial Lactococcus: Lactobacillus: E. faecium UBEF-41 ratio of 2:1:1 and a concentration of approximately 7 log cfu mL−1 until challenge vs. pathogen. L. monocytogenes ATCC 7644 was also inoculated in same media to get approximately 4 log cfu mL−1. Growth curves in skim milk and BHI at 4, 10 and 30 °C, respectively were studied for: (i) LAB formulation; (ii) L. monocytogenes and (iii) LAB vs. L. monocytogenes. When challenged with LAB, at 30 °C in milk, L. monocytogenes was not detectable after day-3 and in BHI it decreased below log cfu mL−1 after day-5. At 10 and 4 °C, in both media, L. monocytogenes counts were always significantly lower (p < .001) than the counts of L. monocytogenes alone from day-2 for milk at 4 °C and BHI at 10 °C and from day-7 for BHI at 4 °C and milk at 10 °C. In conclusion, the proposed formulation was able to limit L. monocytogenes in vitro growth, even at refrigeration temperature

Antibody response against HERV-W env surface peptides differentiates multiple sclerosis and neuromyelitis optica spectrum disorder

A specific humoral immune response against HERV-W envelope surface (env-su) glycoprotein antigens has been reported in serum of patients with multiple sclerosis (MS). However, it has not been evaluated to date in patients with neuromyelitis optica spectrum disorder (NMOSD)

Indici per la valutazione della qualit? ecologica dei laghi

Collection of methods to evaluate lake quality using biological element

The Italian long-term ecosystem research (LTER-Italy) network: results, opportunities, and challenges for coastal transitional ecosystems

1 - The Long-Term Ecosystem Research (LTER) network, now a global reality, was founded on a combination of long-term ecological studies, short-term experiments, and comparisons among sites and eco-domains. 2 - The LTER-Italy network was officially established as a formal member of the LTER international network in 2006, following a wider on-going process in Europe; it currently consists of 22 sites representing the main ecosystem typologies of Italy. Four coastal transitional ecosystem sites are included in the LTER-Italy network: on the northern Peninsula, these include the Venice Lagoon and the lagoons of the Po River Delta, which are characterized by a temperate climate and the influence of tides; and in the southern sector, these include the coastal ecosystems of Sardinia and the Mar Piccolo of Taranto, which are characterized by a Mediterranean climate and the absence of sensible tides. 3 - In this paper, we present and discuss three main issues: the LTER-International and LTER-Europe context, emphasising the most practical issues and activities that must be addressed for the effective organization and maintenance of LTER networks; the history, structure, and perspectives of the national LTER-Italy network; and the opportunities, strengths, and weaknesses related to participation of the LTER-Italy network in the study of coastal transitional ecosystems