Fundamentals of Applied Smouldering Combustion

Smouldering combustion is defined as a flameless oxidation reaction occurring on the surface of the condensed phase (i.e., solid or liquid). Traditional research on smouldering was related to economic damages, fire risk, and death, due to the release of toxic gases and slow propagation rates. Recently, smouldering has been applied as an intentional, engineering technology (e.g., waste and contaminant destruction). Smouldering involves the transport of heat, mass, and momentum in the solid and fluid phases along with different chemical reactions. Therefore, numerical models are essential for the fundamental understanding of the process. Smouldering models either neglected heat transfer between phases (i.e., assumed local thermal equilibrium) or employed heat transfer correlations (i.e., under local thermal non-equilibrium conditions) not appropriate for smouldering. Thus, the first step of this thesis was to develop and validate a new heat transfer correlation for air flowing through hot sand at conditions appropriated to smouldering. The new correlation was reliable and predicted well heat transfer between phases. The second step was to apply the new correlation along with appropriate chemistry into a one-dimensional model. The model was calibrated to a smouldering experiment of an organic liquid fuel embedded in sand and then confidence in the model was gained by independent simulations of additional experiments. Local thermal non-equilibrium demonstrated to be essential to correctly simulate smouldering of organic liquid fuels embedded in sand. Moreover, a two-step kinetic mechanism showed to be sufficient to simulate the smouldering chemistry. The third step was to use the one-dimensional model to understand the conditions that lead to self-sustaining smouldering and smouldering extinction. A global energy balance was developed, revealing that self-sustaining and extinction conditions occurred when the net energy balance was positive and negative, respectively. The last step was to use the one-dimensional model to conduct a sensitivity analysis of the key practical model parameters. Moreover, a local energy balance was developed and compared with the global energy balance; both were used to explain the physics of the process. It was found that the local energy balance described the moment of extinction, whereas the global energy balance predicted extinction in advance. Overall, this thesis presented new insights into the interplay between heat transfer and chemical reactions along with the understanding of the conditions that lead to self-sustaining smouldering and smouldering extinction

Effects of dislocation density on injection and temperature sensitivity of InGaN LED emission spectra: a combined experimental and simulation approach

The aim of this paper is to describe a combined simulation and characterization activity carried out on blue LEDs grown on templates with different threading dislocation densities (TDDs)

model driven reverse engineering approaches a systematic literature review

This paper explores and describes the state of the art for what concerns the model-driven approaches proposed in the literature to support reverse engineering. We conducted a systematic literature review on this topic with the aim to answer three research questions. We focus on various solutions developed for model-driven reverse engineering, outlining in particular the models they use and the transformations applied to the models. We also consider the tools used for model definition, extraction, and transformation and the level of automation reached by the available tools. The model-driven reverse engineering approaches are also analyzed based on various features such as genericity, extensibility, automation of the reverse engineering process, and coverage of the full or partial source artifacts. We describe in detail and compare fifteen approaches applying model-driven reverse engineering. Based on this analysis, we identify and indicate some hints on choosing a model-driven reverse engineering approach from the available ones, and we outline open issues concerning the model-driven reverse engineering approaches

Infection by Mycobacterium caprae in three cattle herds in Emilia-Romagna Region, Northern Italy

Bovine tuberculosis (bTB) is a contagious chronic disease associated with progressive emaciation (starvation) and tubercles (granuloma) formation commonly caused by Mycobacterium bovis. In cattle, M. caprae may also be responsible for bTB. In EU, human tuberculosis due to M. bovis had a notification rate of 0.04 cases per 100,000 inhabitants in 2017, but data did not include M. caprae human infections. From September 2018 to April 2019, bTB outbreaks were investigated in three neighbouring cattle herds in Parma province, Northern Italy. Parma municipality belongs to an officially free of bovine tuberculosis (OTF) Italian region. Official testing on cattle herds, performed every three years as legally required, revealed no positive animals. Tubercular lesions were found during the post mortem (PM) examination of slaughtered cattle and M. caprae genotype SB0418/VNTR 4,3,5,3,4,5,2,2,4,3,15,5 was isolated. This report confirms the crucial importance of PM veterinary inspection at slaughterhouse, despite the OTF status of cattle herds

Italian version of the Cumberland Ankle Instability Tool (CAIT-I)

Study design: Evaluation of the psychometric properties of a translated, culturally adapted questionnaire. Objective: Translating, culturally adapting, and validating the Italian version of the Cumberland Ankle Instability Tool (CAIT-I). Summary of background data: Ankle sprains are one of the most common musculoskeletal injuries and can lead to chronic ankle instability (CAI). The International Ankle Consortium recommends the Cumberland Ankle Instability Tool (CAIT) as a valid and reliable self-report questionnaire assessing the presence and severity of CAI. At this moment, there is no validated Italian version of CAIT. Methods: The Italian version of the CAIT (CAIT-I) was developed by an expert committee. Test-retest reliability of the CAIT-I was measured in 286 healthy and injured participants within a 4-9-day period, by using Intraclass Correlation Coefficients (ICC2,1). Construct validity, exploratory factor analysis, internal consistency and sensitivity were examined in a sample of 548 adults. Instrument responsiveness over 4 time points was determined in a subgroup of 37 participants. Results: The CAIT-I demonstrated excellent test-retest reliability (ICC≥0.92) and good internal consistency (α = .84). Construct validity was confirmed. Identified cut-off for the presence of CAI was 24.75, with sensitivity= 0.77 and specificity= 0.65. There were significant differences across time for CAIT-I scores (P < .001), demonstrating responsiveness to change, but no floor or ceiling effects. Conclusion: The CAIT-I demonstrates acceptable psychometric performance as a screening and outcome measure. The CAIT-I is a useful tool to assess the presence and severity of CAI

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues

Electroluminescence (EL) characterization of InGaN/GaN light-emitting diodes (LEDs), coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of current- and temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs). First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional) classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i) the approximations in the transport description through the multi-quantum-well active region, (ii) the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii) the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10−30 cm6/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary attempt at uncertainty quantification confirms, beyond the present case, the need for an improved description of carrier transport and microscopic radiative and nonradiative recombination mechanisms in device-level LED numerical models

Influence of Lactobacillus kefiri on Intestinal Microbiota and Fecal IgA Content of Healthy Dogs

The increasing incidence of gastrointestinal tract pathologies in dogs and the worrisome topic of antibiotic resistance have raised the need to look for new therapeutic frontiers. Of these, the use of probiotics represents a potential therapeutic alternative. Lactobacillus kefiri (Lk) is a species of Lactobacillus isolated from kefir. Previous studies have demonstrated that its administration in mice downregulates the expression of proinflammatory mediators and increases anti-inflammatory molecules in the gut immune system. It also regulates intestinal homeostasis, incrementing immunoglobulin A (IgA) secretion. Since Lk has never been studied as a single probiotic in dogs, the aim of this study was to evaluate the safety of Lk in dogs, and its effect on IgA secretion and on intestinal microbiota composition. Ten healthy dogs without a history of gastrointestinal diseases were included. The dogs received Lk at a dose of 107 live microorganisms orally, once daily for 30 days. The fecal samples were tested before administration, in the middle, at the end, and 30 days after discontinuation. The IgA secretion concentration and the microbiota composition were evaluated on the fecal samples. The results in this study suggested that Lk did not influence the concentration of IgA, nor significant changes of the intestinal microbiota were observed during and after the treatment. Therefore, additional studies are needed to investigate if a higher daily dosage of Lk can influence the intestinal homeostasis of dogs

When ring makes the difference: coordination properties of Cu2+/Cu+ complexes with sulfur-pendant polyazamacrocycles for radiopharmaceutical applications

Three polyazamacrocyclic ligands, i.e. 1,5,9-tris[2-(methylsulfanyl)ethyl]-1,5,9-triazacyclododecane (TACD3S), 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetrazacyclotridecane (TRI4S) and 1,4,8,11-tetrakis[2-(methylsulfanyl)ethyl]-1,4,8,11-tetrazacyclotetradecane (TE4S), were considered as potential chelators for the medically relevant copper radioisotopes. The ligands have been synthesized through facile, single-step reactions, and their acidity constants have been measured in aqueous solution at 25 degrees C. The kinetic, thermodynamic, electrochemical and structural properties of their Cu2+ and Cu+ complexes were investigated in aqueous solution at 25 degrees C using spectroscopic (UV-Visible, EPR, NMR) and electrochemical techniques (pH-potentiometric titrations, cyclic voltammetry and electrolysis). TACD3S was demonstrated to be unable to stabilize Cu2+, whereas for TRI4S and TE4S the formation of stable monocupric (CuL2+) and monocuprous (CuL+) complexes was detected. TRI4S coordinates Cu(2+)via a [4N] and a [4N]S array of donor atoms while with TE4S only the latter geometry exists. The thermodynamic stability and the kinetic inertness of the copper complexes formed by TACD3S, TRI4S and TE4S were compared with those previously reported for 1,4,7,10-tetrakis-[2-(methylsulfanyl)ethyl]-1,4,7,10-tetrazacyclododecane (DO4S) to unravel the influence of the ring size and the nitrogen donor array on the copper chelation properties of these sulfur-rich macrocycles. The copresence of four nitrogen atoms is an essential feature to allow effective copper coordination when a 12-member ring is employed, as the Cu2+-DO4S complexes were far more stable than those of Cu2+-TACD3S. Furthermore, the larger ring size of TRI4S and TE4S, when compared to DO4S, progressively increases the rate of the Cu2+ complexation reactions but decreases the thermodynamic stability of the Cu2+ complexes. Despite this, the ability of TRI4S and TE4S to stably accommodate both copper oxidation states makes them very attractive for application in nuclear medicine as they could avoid the demetallation after the biologically triggered Cu2+/Cu+ reduction

Inactivating SARS-CoV-2 Using 275 nm UV-C LEDs through a Spherical Irradiation Box: Design, Characterization and Validation

We report on the design, characterization and validation of a spherical irradiation system for inactivating SARS-CoV-2, based on UV-C 275 nm LEDs. The system is designed to maximize irradiation intensity and uniformity and can be used for irradiating a volume of 18 L. To this aim: (i) several commercially available LEDs have been acquired and analyzed; (ii) a complete optical study has been carried out in order to optimize the efficacy of the system; (iii) the resulting prototype has been characterized optically and tested for the inactivation of SARS-CoV-2 for different exposure times, doses and surface types; (iv) the result achieved and the efficacy of the prototype have been compared with similar devices based on different technologies. Results indicate that a 99.9% inactivation can be reached after 1 min of treatment with a dose of 83.1 J/m2

Elucidating the characteristic energy balance evolution in applied smouldering systems

Applied smouldering systems are emerging to solve a range of environmental challenges, such as remediation, sludge treatment, off-grid sanitation, and resource recovery. In many cases, these systems use smouldering to drive an efficient waste-to-energy process. While engineers and researchers are making strides in developing these systems, the characteristic energy balance trends have not yet been well-defined. This study addresses this topic and presents a detailed framework to uncover the characteristic energy balance evolution in applied smouldering systems. This work provides new experimental results; a new, validated analytical description of the cooling zone temperature profile at steady-state conditions; insight into the characteristic temperature changes over time; a re-analysis of published data; and a robust framework to contextualize the global energy balance results from applied smouldering systems. Altogether, this study is aimed to support researchers and engineers to better understand smouldering system performance to further the development of environmentally beneficial applications