Controlling the Er content of porous silicon using the doping current intensity

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process

Laboratorio online: tutoring e vantaggi per lo studente universitario

Il presente lavoro nasce con l’intento di realizzare una ricerca che ha come obiettivo principale quello di analizzare la funzione del tutoring e dei laboratori online su un gruppo di matricole frequentanti il primo anno del Corso di Laurea di Scienze dell’Educazione dell’Università di Cagliari. In tali attività, ruolo cruciale è svolto dal tutor online che funge da facilitatore e contribuisce a chiarire e a raggiungere il conseguimento degli obiettivi educativi e delle interazioni. Il tutor induce lo sviluppo di apprendimento autonomo dei singoli discenti, facendo leva sulla loro curiosità, individuando il loro bisogni formativi, formulando obiettivi compatibili con le loro possibilità e identificando le risorse per loro più adeguate. Partendo da questi presupposti ci siamo chiesti quale sia stata la soddisfazione generale sul ruolo del tutor e l’efficacia del laboratorio in termini di percezione dell’aumento delle proprie abilità di problem solving, dell’autostima, della motivazione, del locus of control e delle competenze informatiche. In generale, si può affermare che l’esperienza del laboratorio di didattica si è rivelata positiva e ha rappresentato un elemento di supporto per gli studenti che vi hanno partecipato

Expression analysis of HLA-E and NKG2A and NKG2C receptors points at a role for natural killer function in ankylosing spondylitis

Background. Ankylosing Spondylitis (AS) is a complex chronic inflammatory disease strongly associated with the majority of HLA-B27 alleles. HLA-E are non-classical MHC class I molecules that specifically interact with the natural killer receptors NKG2A (inhibitory) and NKG2C (activating), and have been recently proposed to be involved in AS pathogenesis. Objectives: To analyze the expression of HLA-E and the CD94/NKG2 pair of receptors in HLA-B27 positive AS patients and healthy controls (HC) bearing the AS-associated, B*2705 and the non-AS-associated, B*2709 allele. Methods: The level of surface expression of HLA-E molecules on CD14 positive peripheral blood mononuclear cell was evaluated in 21 HLA-B*2705 patients with AS, 12 HLA-B*2705 HC, 12 HLA-B*2709 HC and 6 HLA-B27 negative HC, using the monoclonal antibody MEM-E/08 by quantitative cytofluorimetric analysis. The percentage and density of expression of HLA-E ligands NKG2A and NKG2C were also measured on CD3-CD56+ NK cells. Results. HLA-E expression in CD14 positive cells was significantly higher in AS patients (587.0 IQR 424-830) compared to B*2705 HC (389 IQR 251.3-440.5, p=0.0007), B*2709 HC (294.5 IQR 209.5-422, p=0.0004) and HLA-B27 negative HC (380 IQR 197.3-515.0, p=0.01). A higher number of NK cells expressing NKG2A compared to NKG2C was found in all cohort analysed as well as a higher cell surface density. Conclusion: The higher surface level of HLA-E molecules in AS patients compared to HC, concurrently with a prevalent expression of NKG2A, suggests that the crosstalk between these two molecules might play a role in AS pathogenesis accounting for the previously reported association between HLA-E and AS

Electrochemical synthesis of polyaniline/metal-based anodes and their use in microbial fuel cell

A limited number of metals may be suitable as bioanode material: noble metals, such as gold and platinum, could be the optimum choice being electrochemically inert in the operational potential window of the bioelectrochemical system. However, high costs limit their wide scale application. Even though its antimicrobial nature, copper is being considered as a promising alternative anode material, due to its high conductivity, that allows minimising the electrode material costs. Literature research indicated that high-performing electrochemically active biofilms may be grown on this metal. In the present work, gold and copper substrates have been coated by a conductive polymer (PANI), using a layer – by – layer procedure: surface grafting by reduction of 4-nitrobenzendiazonium salt was followed by reduction of nitro- to amino-groups; PANI was electrodeposited on this under-layer. The synthesized anodes were tested as working electrodes (WE) in a microbial fuel cell fed with anaerobic sludge and acetate; to assess the growth of the biofilm on the WE surface, the trend of the bioelectrocatalytic current of acetate oxidation was monitored over time. Cyclic voltammetries reveal the presence of typical redox couples related to the presence of electroactive microorganisms on the electrode surface. Preliminary data show bioelectrochemical activity on polyaniline-coated metal surfaces

Syngas production, clean-up and wastewater management in a demo-scale fixed-bed updraft biomass gasification unit

This paper presents the experimental development at demonstration scale of an integrated gasification system fed with wood chips. The unit is based on a fixed-bed, updraft and air-blown gasifier-with a nominal capacity of 5 MWth-equipped with a wet scrubber for syngas clean-up and an integrated chemical and physical wastewater management system. Gasification performance, syngas composition and temperature profile are presented for the optimal operating conditions and with reference to two kinds of biomass used as primary fuels, i.e., stone pine and eucalyptus from local forests (combined heat and power generation from this kind of fuel represents a good opportunity to exploit distributed generation systems that can be part of a new energy paradigm in the framework of the circular economy). The gasification unit is characterised by a high efficiency (about 79-80%) and an operation stability during each test. Particular attention has been paid to the optimisation of an integrated double stage wastewater management system-which includes an oil skimmer and an activated carbon adsorption filter-designed to minimise both liquid residues and water make-up. The possibility to recycle part of the separated oil and used activated carbon to the gasifier has been also evaluated

Dust attenuation law in JWST galaxies at z = 7-8

Attenuation curves in galaxies depend on dust chemical composition, content, and grain size distribution. Such parameters are related to intrinsic galaxy properties such as metallicity, star formation rate, and stellar age. Due to the lack of observational constraints at high redshift, dust empirical curves measured in the local Universe (e.g. Calzetti and SMC curves) have been employed to describe the dust attenuation at early epochs. We exploit the high sensitivity and spectral resolution of the JWST to constrain the dust attenuation curves in high-z galaxies. Our goals are to check whether dust attenuation curves evolve with redshift and quantify the dependence of the inferred galaxy properties on the assumed dust attenuation law. We develop a modified version of the SED fitting code BAGPIPES by including a detailed dust attenuation curve parametrization. Dust parameters are derived, along with galaxy properties, from the fit to the data from FUV to mm bands. Once applied to three star-forming galaxies at z = 7-8, we find that their attenuation curves differ from local templates. One out of three galaxies shows a characteristic MW bump, typically associated to the presence of small carbonaceous dust grains such as PAHs. This is one of the first evidences suggesting the presence of PAHs in early galaxies. Galaxy properties such as stellar mass and SFR inferred from SED fitting are strongly affected by the assumed attenuation curve, though the adopted star formation history also plays a major role. Our results highlight the importance of accounting for the potential diversity of dust attenuation laws when analyzing the properties of galaxies at the EoR, whose dust properties are still poorly understood. The application of our method to a larger sample of galaxies observed with JWST can provide us important insights into the properties of dust and galaxies in the early universe.Comment: 19 pages, 10 figure

Skin rash and response to cetuximab treatment: a retrospective single-center analysis

Background: The standard of care for patients with recurrent/metastatic head and neck squamous cell cancer (R/M HNSCC) not susceptible for surgery or reirradiation is chemotherapy with 5-FU and cisplatin plus cetuximab. Skin rash (SR) is a common adverse event of cetuximab. In patients treated with cetuximab for colorectal cancer there is strong evidence of a better outcome in those who undergo moderate or high grade of SR, and some retrospective data seem to confirm this finding in HNSCC. We report our experience. Materials and methods: We retrospectively reviewed 107 patients treated with cetuximab for R/M HNSCC from January 2014 to December 2016. Patients were divided in two groups by the grade of SR (G0-1 and G2-4), conforming to Common Terminology Criteria for Adverse Events (CTCAE) v 4.0. Progression-free survival (PFS) was computed as time of progression or death since the date of assessment of recurrent/metastatic disease. Overall response rate (ORR) was computed as the sum of partial and complete responses and evaluated according to RECIST 1.1. PFS and ORR were correlated to the grade of rash. Results: 67 patients were evaluable for PFS: among them PFS was significantly longer (p 0.0014) in those who underwent a G2-4 rash (9,3 months) vs G0-1 (4,9 months). Hazard Ratio was 2,445 (CI 1.412-4.232). 95 patients were evaluable for ORR: among them G0-1 group had 4,2%, while G2-4 group had 36,8% of ORR. Conclusions: Our results support data of literature on improved outcome according to the development of skin rash in HNSCC. SR might be considered a predictive marker of response in these patients; nonetheless further ad hoc studies would be interesting

Reinforcing and neurochemical effects of cannabinoid CB1 receptor agonists, but not cocaine, are altered by an adenosine A2A receptor antagonist

Several recent studies suggest functional and molecular interactions between striatal adenosine A2A and cannabinoid CB1 receptors. Here, we demonstrate that A2A receptors selectively modulate reinforcing effects of cannabinoids. We studied effects of A2A receptor blockade on the reinforcing effects of delta‐9‐tetrahydrocannabinol (THC) and the endogenous CB1 receptor ligand anandamide under a fixed‐ratio schedule of intravenous drug injection in squirrel monkeys. A low dose of the selective adenosine A2A receptor antagonist MSX‐3 (1 mg/kg) caused downward shifts of THC and anandamide dose‐response curves. In contrast, a higher dose of MSX‐3 (3 mg/kg) shifted THC and anandamide dose‐response curves to the left. MSX‐3 did not modify cocaine or food pellet self‐administration. Also, MSX‐3 neither promoted reinstatement of extinguished drug‐seeking behavior nor altered reinstatement of drug‐seeking behavior by non‐contingent priming injections of THC. Finally, using in vivo microdialysis in freely‐moving rats, a behaviorally active dose of MSX‐3 significantly counteracted THC‐induced, but not cocaine‐induced, increases in extracellular dopamine levels in the nucleus accumbens shell. The significant and selective results obtained with the lower dose of MSX‐3 suggest that adenosine A2A antagonists acting preferentially at presynaptic A2A receptors might selectively reduce reinforcing effects of cannabinoids that lead to their abuse. However, the appearance of potentiating rather than suppressing effects on cannabinoid reinforcement at the higher dose of MSX‐3 would likely preclude the use of such a compound as a medication for cannabis abuse. Adenosine A2A antagonists with more selectivity for presynaptic versus postsynaptic receptors could be potential medications for treatment of cannabis abuse