Modelling, diagnostics and experimental analysis of plasma assisted processes for material treatment

This work presents results from experimental investigations of several different atmospheric pressure plasmas applications, such as Metal Inert Gas (MIG) welding and Plasma Arc Cutting (PAC) and Welding (PAW) sources, as well as Inductively Coupled Plasma (ICP) torches. The main diagnostic tool that has been used is High Speed Imaging (HSI), often assisted by Schlieren imaging to analyse non-visible phenomena. Furthermore, starting from thermo-fluid-dynamic models developed by the University of Bologna group, such plasma processes have been studied also with new advanced models, focusing for instance on the interaction between a melting metal wire and a plasma, or considering non-equilibrium phenomena for diagnostics of plasma arcs. Additionally, the experimental diagnostic tools that have been developed for industrial thermal plasmas have been used also for the characterization of innovative low temperature atmospheric pressure non equilibrium plasmas, such as dielectric barrier discharges (DBD) and Plasma Jets. These sources are controlled by few kV voltage pulses with pulse rise time of few nanoseconds to avoid the formation of a plasma arc, with interesting applications in surface functionalization of thermosensitive materials. In order to investigate also bio-medical applications of thermal plasma, a self-developed quenching device has been connected to an ICP torch. Such device has allowed inactivation of several kinds of bacteria spread on petri dishes, by keeping the substrate temperature lower than 40 degrees, which is a strict requirement in order to allow the treatment of living tissues

Vibrações de rede e ligas binária : um modelo baseado no funcional de densidade

Orientador: Luiz Guimarões FerreiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb WataghinResumo: Neste trabalho estudamos os mecanismos de crescimento durante a epitaxia de estruturas III-V baseadas na liga InP. Em particular, o principal objetivo foi correlacionar os mecanismos cinéticos durante a nucleação de nanoestruturas auto-formadas com as propriedades estruturais da camada que serve de substrato. Todas as amostras foram crescidas usando um sistema de epitaxia por feixe químico (CBE). De forma geral as amostras foram caracterizadas usando microscopia de força atômica (AFM), microscopia eletrônica de transmissão (TEM), difração de elétrons de alta energia (RHEED) e difração de raios-X. Na primeira parte deste trabalho correlacionamos as mudanças morfológicas nos filmes homoepitaxiais de InP com o padrão de RHEED exibido durante o crescimento epitaxial. Mostramos que as mudanças morfológicas de 3D para 2D com os parâmetros de crescimento estão diretamente relacionadas com as reconstruções superficiais 2x1 e 2x4, respectivamente. Além disso, indicamos que a formação de defeitos morfológicos é devido à dimerização In-P, através da ativação local do mecanismo de bias na difusão. Por outro lado, também investigamos o efeito dos parâmetros de crescimento (temperatura, taxa de crescimento e quantidade de material) na nucleação e auto-formação de ilhas de InP sobre InGaP/GaAs. Na segunda parte desta tese concentramos nossa atenção no efeito das propriedades da camada buffer de InGaP sobre nanoestruturas auto-formadas, principalmente sobre a sua organização espacial. Para tanto, em primeiro lugar, investigamos as propriedades de bulk da liga de InGaP e a dependência com os parâmetros de crescimento. Nossos resultados mostram que o InGaP exibe tanto ordenamento atômico de rede quanto modulação de composição. Estes dois fenômenos estão correlacionados com o tipo de reconstrução superficial. Em específico, a liga de InGaP apresenta ordenamento CuPtB quando a superfície exibe reconstrução superficial 2x1, conforme descrito na literatura. Por outro lado, a reconstrução superficial 2x4 desempenha um papel importante no fenômeno de modulação de composição. De fato, tanto a modulação de composição quanto a morfologia superficial do filme depende dos mecanismos cinéticos de superfície, que envolvem tanto os átomos adsorvidos de In quanto de Ga. Por fim mostramos que a modulação de composição na liga de InGaP pode organizar espacialmente a nucleação de ilhas de InP em uma rede quadrada. Além disso, mostramos que é possível criar redes bidimensionais de pontos quânticos de InAs/GaAs a partir do arranjo espacialmente ordenado das ilhas de InP/InGaPAbstract: In this work we study the growth mechanisms during epitaxy of III-V structures based on InP. The main goal was to correlate the kinetic mechanisms during nucleation of self-assembled nanostructures with the bulk properties of the buffer layer. All samples were grown by chemical beam epitaxy (CBE) and characterized using atomic force microscopy (AFM), transmission electron microscopy (TEM), reflection high-energy electron diffraction (RHEED) and X-ray diffraction. In the first part of this work we correlate the morphological changes in homoepitaxial InP films with the RHEED pattern during growth process. We show that the morphological transition from 3D to 2D with growth parameters is related to changes in surface reconstruction, from 2x1 to 2x4. Moreover, we point out that the formation of morphological defects is due to mixed In-P dimerization, via the local activation of the diffusion bias mechanism. On the other hand, we also investigate the influence of the growth parameters (temperature, growth rate and amount of deposited material) on the nucleation and selfassembly of InP islands grown on InGaP/GaAs layers. In the second part of this work we concentrate our attention on the InGaP bulk properties, and their effect on the self-assembled InP nanostructures, mainly regarding their spatial ordering. In this way, we first investigate the dependence of InGaP bulk properties with the growth parameters. Our results show that our InGaP layers exhibit atomic ordering as well as compositional modulation. Both phenomena are correlated to the surface reconstruction exhibited by the InGaP surface during growth process. The InGaP alloy presents CuPtB atomic ordering when the RHEED pattern shows 2x1 reconstruction, in agreement with reports in literature. On the other hand, the 2x4-type reconstruction plays an important role in the compositional modulation phenomena. Actually, both compositional modulation and surface morphology of InGaP films depend on surface kinetic mechanisms, and thus on In and Ga adatom mobilities. At last we show that the compositional modulation in the InGaP alloy can be used to organize spatially the InP islands in a square lattice. Moreover, we point out that it is possible to produce bidimensional lattices of InAs/GaAs quantum dots starting from a template of laterally organized InP/InGaP nanostructuresDoutoradoFísicaDoutor em Ciência

Are There Any Parameters Missing in the Mathematical Models Applied in the Process of Spreading COVID-19?

On 11 March 2020, coronavirus disease 2019 (COVID-19) was declared a pandemic by the World Health Organization (WHO). As of 12.44 GMT on 15 January 2021, it has produced 93,640,296 cases and 2,004,984 deaths. The use of mathematical modelling was applied in Italy, Spain, and UK to help in the prediction of this pandemic. We used equations from general and reduced logistic models to describe the epidemic development phenomenon and the trend over time. We extracted this information from the Italian Ministry of Health, the Spanish Ministry of Health, Consumer Affairs, and Social Welfare, and the UK Statistics Authority from 3 February to 30 April 2020. We estimated that, from the seriousness of the phenomenon, the consequent pathology, and the lethal outcomes, the COVID-19 trend relate to the same classic laws that govern epidemics and their evolution. The curve d(t) helps to obtain information on the duration of the epidemic phenomenon, as its evolution is related to the efficiency and timeliness of the system, control, diagnosis, and treatment. In fact, the analysis of this curve, after acquiring the data of the first three weeks, also favors the advantage to formulate forecast hypotheses on the progress of the epidemic

IMC-BFMNU: Un índice estructural relacionado a la masa grasa

Introduction: Body mass index (BMI) provides little information on body composition. For example, two people with the same BMI might have different body compositions. In this sense, the development of a new BMI able to provide body composition information is of clinical and scientific interest. The aim of the study was to suggest a new modified BMI formula.Material and methods: A total of 108 subject, females 56 and males 52, 0-73 years old, in various physiopathological conditions were evaluated. Data were collected and processed by a program that through anthropometric measurements calculates classic BMI, volume, surface, V/S (that we can defined like a body-thickness “pseudospessore”) and the new BMI-BFMNU.Results: The basic formula (BMI =Body Mass [kg]/Height [m2]) uses the height squared as the value of the body surface, although this is only an approximation of the real surface, whereas using the real surface instead, the new BMI reflects better the ratio between the body volume and its surface. The ratio called "pseudospessore" is already used in literature from the BFMNU (Italian acronym refereed to Biologia e Fisiologia Modellistica della Nutrizione Umana) method and has been shown to be related to the amount of fat.Conclusions: Using the BMI-BFMNU, it is possible to obtain an indication of the body structure related to the amount of fat. The consequence is that the obtained numerical values do not coincide with the traditional BMI’s values and will refer to different normal ranges. For instance, a person may be in the range of normal weight for both BMI measurements, but only the BMI-BFMNU detects whether a person has a higher or lower fat content considering the individual’s category. This study opens up to new possible future developments on the application of the new BMI that will allow a more accurate assessment and classification of patients.Introducción: El índice de masa corporal (IMC) proporciona poca información sobre la composición corporal. Por ejemplo, dos personas con el mismo IMC pueden presentar composiciones corporales muy diferentes. Por tanto, sería de gran interés clínico y científico encontrar un nuevo IMC que proporcione información adicional sobre la composición corporal. El objetivo del estudio fue encontrar una nueva fórmula de IMC.Material y métodos: Un total de 108 sujetos, 56 mujeres y 52 hombres, de entre 0-73 años, con diversas condiciones fisiopatológicas fueron evaluados. Los datos fueron recolectados y procesados por un programa que a través de medidas antropométricas calculó el IMC clásico, volumen, superficie, V/S (que puede ser definido como pseudoespesor corporal “pseudospessore”) y el nuevo IMC-BFMNU. Resultados: La fórmula básica (IMC = Masa corporal [kg]/Altura [m2]) usa la altura al cuadrado como el valor de la superficie corporal, aunque esto es solo una aproximación de la superficie real, mientras que, al usar la superficie real, el nuevo IMC refleja mejor la relación entre el volumen corporal y su superficie. La proporción denominada "pseudoespesor" ya se utiliza en la literatura dentro del método BFMNU (acrónimo italiano referido a Biologia e Fisiologia Modellistica della Nutrizione Umana) y que se ha demostrado que está relacionada con la cantidad de grasa. Conclusiones: Utilizando el IMC-BFMNU, es posible obtener una indicación de la estructura corporal relacionada con la cantidad de grasa. La consecuencia es que los valores numéricos obtenidos no coinciden con los valores del IMC tradicional y se refieren a diferentes rangos de normalidad. Por ejemplo, una persona puede estar en el rango de peso normal para ambas mediciones de IMC, pero solo el IMC-BFMNU puede detectar si una persona tiene un mayor o menor contenido de grasa considerando la categoría del individuo. Este estudio se abre a nuevos posibles desarrollos futuros sobre la aplicación del nuevo IMC que permitirá una valoración y clasificación más precisa de los pacientes

Experimental investigation on the influence of target physical properties on an impinging plasma jet

The present work aims to investigate the interaction between a plasma jet and targets with different physical properties. Electrical, morphological and fluid-dynamic characterizations were performed on a plasma jet impinging on metal, dielectric and liquid substrates by means of Intensified Charge-Coupled Device (ICCD) and high-speed Schlieren imaging techniques. The results highlight how the light emission of the discharge, its time behavior and morphology, and the plasma-induced turbulence in the flow are affected by the nature of the target. Surprisingly, the liquid target induces the formation of turbulent fronts in the gas flow similar to the metal target, although the dissipated power in the former case is lower than in the latter. On the other hand, the propagation velocity of the turbulent front is independent of the target nature and it is affected only by the working gas flow rate

Curiosities of Weight Loss Diets of the Last 60 Years

Lately, we've witnessed the emergence of obesity as a prominent concern for public health and the economy. This issue commands serious attention, impacting millions worldwide, particularly in the most developed nations. Practical approaches to tackling obesity involve tailored physical activity and dietary interventions overseen by qualified healthcare professionals. Nonetheless, some individuals opt for quicker routes, embracing dietary regimens that promise rapid and effortless weight reduction yet lack substantiated scientific backing. Given the potential hazards these approaches pose to well-being, this calls for immediate address, occasionally leading to unexpected and severe consequences. In this review, we aim to analyze the curiosities of popular diets embraced by adults from the 1960s to the present day, including the scientific justification that supports or contradicts their effectiveness.N.S.O. was supported by the Universidad de Alicante, Ministerio de Universidades and the European Union ‘NextGeneration EU/PRTR’ through 2022–2024 Margarita Salas grant (MARSALAS22-23)

Artificial quantum confinement in LAO3/STO heterostructure

Heterostructures of transition metal oxides (TMO) perovskites represent an ideal platform to explore exotic phenomena involving the complex interplay between the spin, charge, orbital and lattice degrees of freedom available in these compounds. At the interface between such materials, this interplay can lead to phenomena that are present in none of the original constituents such as the formation of the interfacial 2D electron system (2DES) discovered at the LAO3/STO3 (LAO/STO) interface. In samples prepared by growing a LAO layer onto a STO substrate, the 2DES is confined in a band bending potential well, whose width is set by the interface charge density and the STO dielectric properties, and determines the electronic band structure. Growing LAO (2 nm) /STO (x nm)/LAO (2 nm) heterostructures on STO substrates allows us to control the extension of the confining potential of the top 2DES via the thickness of the STO layer. In such samples, we explore the dependence of the electronic structure on the width of the confining potential using soft X-ray ARPES combined with ab-initio calculations. The results indicate that varying the thickness of the STO film modifies the quantization of the 3d t2g bands and, interestingly, redistributes the charge between the dxy and dxz/dyz bands

PAP-TEST FEATURES IN A COHORT OF SYSTEMIC SCLEROSIS PATIENTS

Background: Increased incidence of malignancies was frequently reported in systemic sclerosis (SSc), as well as for other autoimmune diseases. Besides the previously observed association with lung cancer1 and the increased risk for breast cancer2, no association with cancer of the cervix has been described in literature. However, cervical uterus malignancy is one of the most frequent cancer in women so that public health programs of screening have been established in several countries worldwide. In Italy, the pap cytology test is recommended every 3 years for all women between 25 and 64 years old. Objectives: To investigate pap-test features in SSc patients. Methods: We retrospectively evaluated a cohort of 80 consecutive female SSc patients (mean age 51.2±12SD years, disease duration 7.9±5.8SD years, limited/diffuse skin subsets 72/8), who underwent to pap cytology tests as screening for cancer of the cervix, during the period between January 1st, 2008 and December 31th, 2014. All patients came from the same geographical area (province of Modena, Northern Italy). Clinical, serological, and instrumental data of SSc patients were collected and related to cytological findings. Results: At gynaecological and pap test evaluations, 55 (68.7%) patients were negative, while 20 (25%) presented inflammatory alterations (i.e. chronic cervicitis); while atypical cells related to cancer or pre-cancerous lesions were found in 5 (6.2%) cases. Namely, 2 women showed cervix cancer (one of them in situ), 1 a vulvar melanoma, 1 a vulvar intraepithelial neoplasia, and 1 an endocervical polyp with immature squamous metaplasia at histology. The frequency of cervix cancer in our series seems to be clearly higher in comparison to the incidence registered in the same geographical area and in the same years (standardized rate 8, 95%IC 5.2-10.7 cases out of 100,000 subjects). At statistical analysis, the atypical cytological findings correlated with serum anti-Scl70 autoantibodies (4/5 vs. 19/75; p=0.022); moreover, the patients with these alterations tended to be older (median 65, range 46-67), if compared to the whole series (p=0.052). No statistical correlations with skin or visceral involvements, smoking history, treatment with immunosuppressors were found. Conclusions: In our SSc patients' series, we found a relatively high frequency of cancerous lesions of the cervix by means of pap test. A significant correlation with anti-Scl70 autoantibodies was also found. These preliminary findings need to be verified in larger controlled epidemiological studies

Validation of a gold standard method for iodine quantification in raw and processed milk, and its variation in different dairy species

Adequate milk consumption significantly contributes to meeting the human iodine recommended daily intake, which ranges from 70 µg/d for infants to 200 µg/d for lactating women. The fulfilment of iodine recommended daily intake is fundamental to prevent serious clinical diseases such as cretinism in infants and goiter in adults. In the present study iodine content was measured in raw and processed commercial cow milk, as well as in raw buffalo, goat, sheep, and donkey milk. Iodine extraction was based on 0.6% (vol/vol) ammonia, whereas iodine detection and quantification were carried out through an inductively coupled plasma mass spectrometer analyzer. Among processed commercial cow milk, partially skimmed pasteurized milk had the greatest iodine content (359.42 µg/kg) and raw milk the lowest (166.92 µg/kg). With regard to the other dairy species, the greatest iodine content was found in raw goat milk (575.42 µg/kg), followed by raw buffalo (229.82 µg/kg), sheep (192.64 µg/kg), and donkey milk (7.06 µg/kg). Repeatability of milk iodine content, calculated as relative standard deviation of 5 measurements within a day or operator, ranged from 0.96 to 1.84% and 0.72 to 1.16%, respectively. The overall reproducibility of milk iodine content, calculated as relative standard deviation of 45 measurements across 3 d of analyses and 3 operators, was 4.01%. These results underline the precision of the proposed analytical method for the determination of iodine content in milk