**4. Conclusions**

The objective of this document was to carry out a methodological analysis of the technologies available for the removal of sulfur in water for human consumption. This review provides a guideline to possible users or possible research in the area of sulfate removal. A user, based on the characteristics of the water, concentration, pH, T, can choose a method that is fit for a given application, considering the available resources (monetary, human, space), and characteristics of the water to be treated

Given the complexity and diversity of the technologies and materials evaluated, choosing the best methodology or material depends on several factors, including equipment availability, technology, operation, maintenance, economy, response speed, efficiency. These factors become more relevant for developing countries like Mexico, where there is a lack of trained technicians, or places with the greatest need for water have limited or no access to replacement parts.

All necessary pretreatment, pH change, use of reagents before or after treatment, installation or initial investment, operation, and maintenance requirements, must be considered when evaluating which methodology is better, especially if there are economic restrictions. When considering biological treatment, it is important to keep in mind the high retention times needed for relevant removal efficiencies. Finally, it is also important to keep in mind that a 98% efficiency removal with a sample below 66 mg L−1 (as is the case of Adsorption Polyaniline) is not the same as a 90% efficiency with concentrations of 3,665 mg L−1 (as in the case of ion exchange).

This review also helps identify the following research gaps and opportunities:

Sulfur water has not been considered for human consumption due to social rejection caused by the characteristic taste and smell of sulfur present in the water. However, this water has the potential to become an important source of drinking water after treatment. This review provides the basis to identify technologies that can be effective at removing sulfate from potential drinking water sources. In particular, for countries like Mexico, there is still room for improvement in developing a methodology that is effective and economic, and that can be used at a large scale in water purification plants. Currently, the best options are physical treatments, such as the use of membranes or adsorbents, but other materials or a combination of them could provide better alternatives.


**1. Introduction**

Thyroid cancer has the most rapidly increasing incidence rate among all major cancers, with a triple increase from 4.5 to 14.4 per 100,000 population during 1974–2013 [1]. It was estimated 52,890 new cases in the United States in 2020 and contributed to 0.36% of all cancer deaths [2,3]. Most primary thyroid cancers are follicular cell-derived epithelial tumors, making up four main pathological carcinoma types: papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC). Medullary thyroid carcinomas (MTC) originate from thyroid parafollicular (C) cells. PTC and FTC are differentiated thyroid cancers, whereas ATC is undifferentiated. PTC constitutes up to 90% of all thyroid malignancies [4], followed by FTC (5–10%), ATC (<2%, typically occurring in the elder patients) and MTC (2%) [5]. As the most common type of well-differentiated thyroid cancer [6], PTC comprises numerous histopathologic variants that are well validated clinically and biologically, including classic variant, follicular variant (encapsulated/well demarcated, with tumor capsular invasion), follicular variant (encapsulated/well demarcated, noninvasive), follicular variant (infiltrative), tall cell variant, hobnail variant, cribriform-morular variant, columnar cell variant and diffuse sclerosing variant [7]. Among all variants, the follicular variant of papillary thyroid carcinoma (FVPTC) is one of the most common diagnoses, representing up to 30% of all thyroid carcinoma cases [8]. FVPTC is subdivided into two subtypes: the infiltrating/diffuse variant (infiltrative FVPTC), which has the metastatic tendency of the classic papillary thyroid carcinoma, and the encapsulated variant (EFVPTC), which may present with no capsular or angiolymphatic invasion or metastases [9,10]. The microscopic diagnostic criteria for EFVPTC are mainly encapsulation or clear demarcation, follicular growth patterns, and nuclear features of papillary carcinoma (enlargement, crowding/overlapping, elongation, irregular contours, grooves, pseudoinclusions and chromatin clearing) [11–14]. Controversies have existed for a long time about whether all EFVPTC cases should be classified as malignancy [15–17]. Evidence suggests that a subset of non-invasive EFVPTC, earlier considered as conventional thyroid cancer, has been demonstrated to be a highly indolent tumor showing an overall risk of recurrence (local, regional and distant) of less than 1% [15,16,18–20]. In 2016, a new terminology Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) has been proposed to name the subset of non-invasive EFVPTC [11] to address the indolent behavior of this tumor and avoid the term "carcinoma" and potential over-treatment.

NIFTP presents the following characteristics: (1) main morphological features, including encapsulation or clear demarcation, follicular growth pattern, no well-formed papillae, no psammoma bodies, <30% solid/trabecular/insular growth pattern, nuclear score 2–3, no tumor necrosis, no high mitotic activity; (2) lack of invasion, which separates this tumor from invasive EFVPTC; (3) a very low risk of the adverse outcome when the tumor is noninvasive [11,21,22]. Histopathological examination of the entire tumor remains the gold standard for NIFTP diagnosis. Of note, the initial exclusionary papillae less than 1% that was subjective to apply has been updated to a 0% cut-off to ensure indolent outcome [22,23]. NIFTP is still an evolving diagnosis, and more data need to be established to substantiate this new entity [24]. As neoplasm develops specific alterations at the proteomic and/or genomic level, molecular marker-based ancillary tests at histological or cytological level may be a great asset in improving the accuracy of the diagnosis of NIFTP [4,11,25,26]. Recently, immunohistochemical test of Programmed Death-Ligand 1 expression has been shown to distinguish invasive EFVPTC from the indolent NIFTP and benign nodules [25], and recommended as an auxiliary aid to pathologists [27].

Galectin-3 (Gal-3), a member of the beta-galactoside-binding protein family that is predominantly localized in the cytoplasm, may translocate to the perinuclear membrane, nucleus and/or secreted from the cytoplasm [28,29]. This protein is involved in various physiological and pathological processes, such as cell proliferation, apoptosis, inflammation, cell adhesion, cellular transformation, tumor progression and metastasis of cancer cells [28,30]. Overexpression of *galectin-3* cDNA in vitro generates a transformed phenotype [31]; conversely, inhibition of Gal-3 expression has suppressed tumor growth in mice tumor models [32]. Gal-3 is a p53 physiological target mediating p53-induced apoptosis at the molecular level; therefore, the aberrant expression of Gal-3 blocks the apoptotic program, promoting the development of cancer [33]. Gal-3 is overexpressed in a high proportion of carcinomas, especially of the papillary histotype, but weak or absent from normal or benign thyroid tissue [29,30,34], suggesting its potential biological role in the malignant transformation of thyroid cells. Gal-3 immunohistochemistry has been reported to assist the diagnosis of FVPTC [29,35]; however, the role of Gal-3 expression as an ancillary marker in reclassification to NIFTP has not yet been determined.

The aim of the current study was to determine whether Gal-3 subcellular expression in histological surgical tissues could serve as a useful biomarker to distinguish indolent NIFTP from invasive EFVPTC.


**1. Introduction**

In the twenty-first century, higher education plays a pivotal role in preparing learners to become more active and independent, responsible members of society and trustworthy people. So, it is experiencing a reconstituted change because of the change in standards and curriculum, science, technological innovation, globalization, international agreements, privatization, human rights, urbanization, and industrialization [1]. Learners nowadays encounter many obvious economic difficulties along

with social, emotional, and environmental issues, such as global warming, criminal attacks, suicide, lack of job security, and poverty.

As research indicated, adults are considered the fundamental elements of the construction of modern society due to their physical and intellectual capability. However, in the real scenario, the majority of the adults do not have the ability to make use of their potency in a convenient way due to the deficiency of guidance and motivation [2] while the notions such as communication skills, objective setting, the way of meal preparation, budget allocating, and time management are often anticipated to be dealt with along the way as students get mature [3]. Expeditiously, the number of social problems has increased such as drug abuse, sexual harassment, and alcoholism and affected the development of empathy with surrounding and having harmony in society. As [4] opine that it is crucially significant that college graduates get in the manpower with the skills to realize sustainable prosperity and success in a competitive and swiftly alternating revolutionary world. However, in accordance with variously conducted studies, today's college graduate often endeavors to join the workplace but are unequipped to satisfy the requirements of today's employers. Also, there is growing frustration over the high-education learners' dearth of the necessary life skills. So, those challenge requires immediate and effective responses from a socially responsible system of education while learners lack home life support to deal with the future life after graduation. High education institutions are working in a complicated and refined era due to the rapid and radical change in terms of personal characteristics and business workplace requirements. In the Fourth Industrial Revolution (FIR), improving learners' core competencies which include personal, intellectual, emotional, and social competencies is the highest priority for preparing learners to be more competitive citizens in the world business economies [5]. Also, it leads to respond learners' needs, to fulfilling their interests. Therefore, ministers of education around the world have acknowledged and identified the necessity and requirement to develop their educational systems to make life skills education a compulsory element and mandatory component in schools' curricula and through extra-curricular activities to help learners navigate the world [6]. Consequently, this topic has been an investigation problem for various studies such as [7] and the like. The main purpose of this research was to identify the significance of preparation of higher education learners for a transformative work environment by improving their life skills. Also, the research aims to investigate how life skills are realized, operationalized, activated, and implemented in teaching and learning strategies to enhance and improve life skills in the high education context.


From Biomass to Biobased Products

*Edited by Eduardo Jacob-Lopes, Leila Queiroz Zepka and Rosangela Rodrigues Dias*

Published in London, United Kingdom

#### From Biomass to Biobased Products http://dx.doi.org/10.5772/intechopen.107581 Edited by Eduardo Jacob-Lopes, Leila Queiroz Zepka and Rosangela Rodrigues Dias

#### Contributors

A. Venkata Ramayya, Abdulbari A. Ahmad, Abdulraqeeb Alwahbi, Adewale Elijah Fadeyi, Aleksandra M. Rozhkova, Ana Cristna de Oliveira Macedo, Antonio Donizeti de Oliveira, Arkady P. Sinitsyn, Aseeya Wahid, Asfaw Gezae Daful, Benito Buendía Quispe, Carlos Yesid Varela Bernal, Celia Kirsch, Daniela Eusébio, Danyang Ying, Derese T. T. Nega, Eduardo Jacob-Lopes, Ekaterina A. Rubtsova, Fabian Giebner, Hani Dammag, Henok Mekonnen Mossissa, Hisashi Miyafuji, Ishka Bless, Jaqueline Torres de Souza, Jordan Pennells, Jose Antonio Mayoral Chavando, Joseph Akpan, João Graciano Mendonca Filho, João Sousa Cardoso, Julio Javier Armijo Carranza, Laila A. Al Khateeb, Lalita Pal, Leila Queiroz Zepka, Luiz Guilherme Costa dos Santos, Luís A.C. Tarelho, Marie Loridon, Mattaparthi Lakshmi Durga, Meegalla R. Chandraratne, Million M. Afessa, Milton Cézar da Silva, Moses Jeremiah Barasa Kabeyi, Muhammad Ahsan Amjed, Natascha Eggers, Noelia del Valle Franco Rondón, Olga G. Korotkova, Oludolapo Akanni Olanrewaju, Pablo Juliano, Raymundo Erazo Erazo, Roberto Robles Calderón, Rosangela Rodrigues Dias, Saheed Olatunbosun Akiode, Sammy N. Aso, Tais Freitas, Takashi Hosoya, Thiago dos Santos Barbosa, Torsten Birth, Valter Silva, Yuki Hirano

#### © The Editor(s) and the Author(s) 2024

The rights of the editor(s) and the author(s) have been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights to the book as a whole are reserved by INTECHOPEN LIMITED. The book as a whole (compilation) cannot be reproduced, distributed or used for commercial or non-commercial purposes without INTECHOPEN LIMITED's written permission. Enquiries concerning the use of the book should be directed to INTECHOPEN LIMITED rights and permissions department (permissions@intechopen.com).

Violations are liable to prosecution under the governing Copyright Law.

Individual chapters of this publication are distributed under the terms of the Creative Commons Attribution 3.0 Unported License which permits commercial use, distribution and reproduction of the individual chapters, provided the original author(s) and source publication are appropriately acknowledged. If so indicated, certain images may not be included under the Creative Commons license. In such cases users will need to obtain permission from the license holder to reproduce the material. More details and guidelines concerning content reuse and adaptation can be found at http://www.intechopen.com/copyright-policy.html.

#### Notice

Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book.

First published in London, United Kingdom, 2024 by IntechOpen IntechOpen is the global imprint of INTECHOPEN LIMITED, registered in England and Wales, registration number: 11086078, 167-169 Great Portland Street, London, W1W 5PF, United Kingdom

British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library

Additional hard and PDF copies can be obtained from<EMAIL_ADDRESS>
From Biomass to Biobased Products Edited by Eduardo Jacob-Lopes, Leila Queiroz Zepka and Rosangela Rodrigues Dias p. cm. Print ISBN 978-1-83769-002-2 Online ISBN 978-1-83769-003-9 eBook (PDF) ISBN 978-1-83769-004-6


*3.2. Mechanical Tests*

The cubic specimens with side a = 150 mm were used for compressive strength determination, with a diameter (d) of 100 mm and height (h) of 200 mm for the cylindrical samples for the splitting tensile strength tests. Three samples were used to test unheated concrete and two were used to test heated concrete. The modulus of elasticity was determined from the stress–strain (σ-ε) using one cylindrical sample (d = 100 mm; h = 200 mm). All E values were expressed in GPa and calculated from σ-ε curves as the stress to strain and strain ratio in the range of 10% to 40% of the ultimate stresses. For all properties six temperature levels were studied: T = 20, 200, 400, 600, 800, and 1000 ◦C. The compressive strength test procedures applied were presented in EN 12390-3 [32], and the splitting Brazilian tests were done according to EN 12390-6 [33].

#### **4. Test Results and Discussion**

### *4.1. Initial Properties*

For B CEMI, B CEMIII, RB CEMI, and RB CEMIII concretes, the initial physical properties of bulk density ρo20◦C and permeability k, and the mechanical properties of compressive strength fc20◦C tensile strength ft20◦C and modulus of elasticity E20◦C were determined after 90 days. The initial measurements, obtained for non-heated concrete properties, are presented in Table 5 and marked with the symbol 20 ◦C.

#### *4.2. Evolution of Bulk Density with Temperature*

The progressive increase of the temperature resulted in free water evaporation and progressive dehydration of the material. The C-S-H, as well as portlandite and calcium carbonate decomposition, were progressive in higher temperatures. As a result, weight loss was observed and the progressive density changes were recorded. The bulk density of B CEMI, B CEMIII, RB CEMI, and RB CEMIII concretes decreased as a function of the temperature. The mean values of bulk density are presented in Figure 2.

**Figure 2.** Bulk density of riverbed aggregates (RB) and basalt (B) concretes made with CEMI and CEMIII concretes; mean value of three samples.

In Figure 2 the bulk densities of the test concretes are presented. The values are mainly related to the type of aggregate: basalt or riverbed. The density of basalt CEMI concrete was 2558.8 kg/m3 and the B CEMIII 2533.2 kg/m3. The RB CEMI and RB CEMIII concrete were 2300.7 and 2315.6 kg/m3, respectively. Apart from the initial values of density observed in the non-heated pristine concrete, the changes of the density with the temperature were quite similar for both cement types.

#### *4.3. Evolution of Compressive Strength and Splitting Tensile Strength with Temperature Exposure*

Figure 3 depicts the average and individual values of compressive strength. From the figure it can be concluded that the compressive strength of unheated concrete was higher for both CEMIII concretes made with basalt and riverbed aggregates. This tendency is maintained at 200 ◦C. When the temperature is higher than 400 ◦C, there are few differences in strength between B CEMI and B CEMIII, as well as between RB CEMI and RB CEMIII concretes. They all presented almost the same strength of 60 MPa.

**Figure 3.** The compressive strength evolution CEMI and CEMIII concretes on basalt and riverbed aggregate.

In Figure 4, the average and individual values of ftT are presented. Heating resulted in a progressive reduction in strength, nevertheless, the differences between CEMI and CEMIII concretes over a whole range of temperatures may be considered insignificant, in the scope of measurement error, or the scatter of results for this mechanical property.

**Figure 4.** The changes in the splitting tensile strength of heated CEMI and CEMIII concretes on basalt and riverbed aggregate.

As has already been shown in previous research, an important aspect in the high temperature behavior of concrete is the thermal stability of aggregates at high temperatures. This can be evaluated by thermo-gravimetric and differential thermal analysis, which indicate the physical or chemical transformation of aggregates. As has already been reported [10], basalt is thermally stable up to 1000 ◦C; above this temperature melting is observed at 1050 ◦C and expansion and gas release both occur.

#### *4.4. Relationship between Stress and Strain, and the Modulus of Elasticity Evaluation*

The stress–strain relationships for the tested concretes are presented in Figure 5. Along with the temperature increase, a change of concrete stiffness was observed, as represented by the slope of the stress–strain curve. For the specimens heated to 600 ◦C and above, the stress–strain curve presents nonlinear behavior in compression due to the presence of cracks, which are closing partially when a compressive load is applied during the test. The similar stress–strain behavior of concrete in compression was observed for hot tested and tested after cooling down [8,15], an important cracking of samples was observed, especially for concretes with siliceous aggregates, heated without loading. The cracking of unloaded concrete was confirmed by the thermal strain evolution observation during heating [6].

The static modulus of elasticity values (ET) of heated B CEMI and B CEMIII, as well as RB CEMI and RB CEMIII, are shown in Figure 6. The pristine non-heated concretes' modulus of elasticity (E20◦C) were 44.4 and 48.9 GPa, respectively, for B CEMI and B CEMIII. For riverbed aggregate RB CEMI and RB CEMIII they were 30.6 and 29.7 GPa. These results show clearly that for concretes with the same volume of cement paste, the modulus of elasticity is related to the nature of the aggregate and is strongly related to concrete density. Higher values of ET were observed for both CEMIII concretes with RB and B aggregates.

A quasi linear decrease in the ET value over the whole range of heating temperatures was observed. The slope of ET decrease is most pronounced in the range of temperatures between 400 and 1000 ◦C (Figure 5). This sharp decrease of stiffness was attributed to crack development due to a mismatch of the strains between the cement paste and aggregates that is observed in this range of temperatures, and an increase in thermal strains resulting from cracking [6,7].

 7R&

**Figure 6.** Modulus of elasticity change with the temperature of CEMI and CEMIII concretes.

From Figure 6 it can be concluded that the relative change of the modulus of elasticity is quasi identical for the concretes tested, and does not depend on cement type. The differences between the modulus of elasticity values of RB CEMI and RB CEMIII are not significant except for differences occurring at 20 ◦C.

#### *4.5. Heated Concrete Permeability Evolution*

For RB CEMI and RB CEMIII, the initial reference permeability, measured on non-heated concrete after exposure to 20 ◦C, reached values of 1.20 × 10−17 m2 and 1.00 × 10−17 m2, respectively. For B CEMI and B CEMIII this permeability was 0.70 × 10−17 m2 and 0.52 × 10−17 m2. With the increase of heating temperature residual permeability was increased. For the specimens heated to 1000 ◦C the permeability could not be measured due to crack development, and the gas flows could not be stabilized, so the permeability could not be measured with the Cembureau set-up. The results of the permeability measurements are presented in Figure 7. For B CEMIII and RB CEMIII concretes generally, lower values of permeability were observed. For the riverbed aggregate concrete RB CEMIII, permeability measured after exposure to high temperatures at 200, 400, 600, and 800 ◦C was systematically slightly lower than for RB CEMI. Basalt aggregate-based concretes provide lower permeability than riverbed ones. Nevertheless, these differences could not be considered significant. For all the concretes heated up to 1000 ◦C, the permeability could not be measured with the Cembureau method due to the significant damage to the concrete and crack development.

**Figure 7.** Effect of heating on the permeability of the test materials: RB CEMI and RB CEMIII, B CEMI and CEMIII. The reference permeability at 20 ◦C and permeability after heating to 200, 400, 600, and 800 ◦C.

#### *4.6. Permeability vs. High Temperature Damage Factor*

Previous studies [34,35] have indicated that the degradation of concrete at high temperatures, arising from a coupled hygro-thermal, chemical (dehydration) and mechanical interaction, can be modelled by means of the isotropic damage theory of Mazars [36]. Following Gawin et al. [9], the total damage *D* may be described by a multiplicative format of mechanical and thermo-chemical damage components, as shown in Equation (2):

$$D = 1 - \frac{E(T)}{E\_0(T\_0)} = 1 - \frac{E(T)}{E\_0(T)} \frac{E\_0(T)}{E\_0(T\_0)} = 1 - (1 - d) \times (1 - V),\tag{2}$$

where V corresponds to the thermo-chemical damage and *d* to the mechanical damage. The term (1 – d) corresponds to E(T) E0(T), and (1–V) to E0(T) E0(T0). In the above equation E0(T0) is the initial value of the static modulus of elasticity, E0(T) is the modulus for mechanically undamaged material expressed in a function of heating temperature, and E(T) represents the static modulus of elasticity of mechanically damaged heated concrete.

Following this approach, in Figure 8 the effect of temperature on the damage parameter for heated concretes is presented. The damage factor was calculated on the basis of the change in the modulus of elasticity with temperature (see Figure 6), leading to Equation (3), and this evaluates the deterioration of the stiffness of the heated concrete samples by comparing them with the parameters found in non-heated concrete:

$$D\_E = \mathbb{1} - E\_T \mathbb{E}\_{20} \circ\_{C\_{\mathcal{L}}} \tag{3}$$

where E20◦C is the static modulus of elasticity tested at 20 ◦C and ET is the value obtained for heated concrete.

The damage factor follows a comparable increasing change for all tested materials and almost reaches the value of 0.9, which means that 90% of the concrete has deteriorated. However, at 400 ◦C the damage value becomes much higher for the basalt aggregate concretes in comparison with the riverbed aggregate ones. Overall, the damage values for the CEMIII concretes appear to be slightly lower than for the CEMI concretes, especially for the basalt-based materials.

**Figure 8.** Damage factor (*DE*) as a function of temperature.

These changes may be qualitatively compared to the change of total damage with temperature of a high performance concrete [9]. However, the damage values obtained and cited in this study are higher (damage of 0.8 at 600 ◦C). The reason for this difference may be due to the heating conditions, and notably the heating rate, which was four times higher in the study by Gawin et al. [9] than in our procedure, and which may provide stronger thermal gradients and therefore greater degradation.

It has already been noted that the changes to the inner micro-structure and permeability of the concrete may be characterized using this mechanistic approach, using damage evaluation to describe the high temperature degradation and/or micro-cracking effects [9,26,37,38]. The results of such a correlation are presented in Figure 9 for all the test materials. One may observe that all the data follow a single master law, independent of cement type or aggregate type. The results follow an exponential relationship, except for the permeability values obtained at 800 ◦C (Equation (4)):

**Figure 9.** Juxtaposition of permeability (log scale) and damage to unheated concretes (20 ◦C) and concretes heated to 200, 400, 600, and 800 ◦C.

In Equation (4) k is the permeability of the heated material, k0 the initial reference permeability, DE the damage factor, and CDE is the material dependent parameter, here equal to 8, which confirms the value obtained for another high performance concreteat elevated temperatures, but based only on the CEMI cement [9]. The CDE value being equal to 8was obtainedfrom the regression curve with the coefficient of determination R2 of 0.86 value. Therefore, the proposed regression curve is limited

in the range of temperature from 20 to 600 ◦C.Three points that do not follow the trend in Figure 9 correspond to permeability values obtained at 800 ◦C. At this temperature, important cracking occurs following the already mentioned nonlinear mechanical behavior.


**2.4 Oxidation-reduction**

Sulfide minerals in mining waste pose several relative resistances to weathering (**Table 1**) [9]. However, due to physicochemical processes, the weathering process presents alterations that influence the composition of water that can drain or percolate in the mining waste.

The oxidation of sulfur minerals is due frequently to their deposition in aerated places where sulfide minerals are thermodynamically unstable. Therefore, pyrite and pyrrhotite, which generally dominate sulfide deposits are the first sulfides to undergo oxidation [Eqs. (3) and (4)] due to their chemical composition. During oxidation process, one mole of pyrite and pyrrhotite with atmospheric oxygen, is the main electron acceptor, and water form Fe2+, 4 and 2 moles of acid, respectively [9]. However, sphalerite, chalcopyrite, galena and arsenopyrite also contribute to the generation of acid drainage [4, 14].

$$\text{FeS}\_2 + \frac{15}{4}\text{O}\_2 + \frac{7}{2}\text{H}\_2\text{O} \rightarrow 2\text{SO}\_4^{2-} + \text{Fe(OH)}\_3 + 4\text{H}^+\tag{3}$$

$$\text{Fe}\_{1-x}\text{S} + \left(2 - \frac{\varkappa}{2}\right) \text{O}\_2 + \varkappa \text{H}\_2\text{O} \rightarrow \text{SO}\_4^{2-} + (1-\varkappa) \text{Fe}^{2+} + 2\varkappa \text{H}^+ \tag{4}$$

#### **Table 1.**

*Relative resistances of sulfide minerals and magnetite in oxidized tailings taken from [9].*

*Mobility of Heavy Metals in Aquatic Environments Impacted by Ancient Mining-Waste DOI: http://dx.doi.org/10.5772/intechopen.98693*

Heat is released when oxidation reaction of metal sulfides occurs. When pyrite is oxidized and form acid, this reaction releases 1440 KJ.mol�1 , heat that is hardly released by an oxidation reaction [15]. The heat generated by that exothermic reaction of pyrite, as long as there is high permeability in the tailings cover, it transports oxygen by convection, increasing oxidation rate of sulfides. However, when a reservoir is saturated with water, advective transport is reduced and the main oxygen transport mechanism is diffusion [14, 16]. In addition, oxygen can be supplied by wind in lateral parts of deposit, where oxygen can migrate upward or reach basal regions by advection, convection and diffusion, [17]. Therefore, low concentrations of oxygen are due to its high consumption in oxidation of sulfides minerals and to a limited supply due to the low permeability that governs waste materials.

When the cover of the tailings dam is depleted in oxygen and the air supply is insufficient, high oxidation of sulfides causes water to be characterized by pH <3, high concentrations of sulfates and metals, for instance Zn, Fe, Pb. Under these scenarios, Fe3+ ion remains in solution and becomes the dominant oxidant of metal sulfides, generating acidity in the environment, Eqs. (5) and (6) show generation of acid from oxidation of pyrite and pyrrhotite [9].

$$\rm FeS\_2 + 14Fe^{3+} + 8H\_2O \to 15Fe^{2+} + 2SO\_4^{2-} + 16H^+ \tag{5}$$

$$Fe\_{(1-x)}\mathbb{S} + (\mathbb{S} - 2\mathbb{x})Fe^{3+} 4H\_2O \to (\mathbb{S} - 3\mathbb{x})Fe^{2+} + \mathbb{S}O\_4^{2-} + 8H^+ \tag{6}$$

## **2.5 Geological factors influencing mobility of heavy metals**

Geological formations are volumes of rocks confined to a certain space, they are formed by different types of rocks (igneous, sedimentary, and metamorphic) of different nature, they can enclose mineral deposits of great economic value. Metallic mineral deposits are generally enriched in sulfides such as: pyrite (FeS2), pyrrhotite (Fe(1-x) S), sphalerite (ZnS), chalcopyrite (FeCuS2), arsenopyrite (FeAsS), galena (PbS) and cubanite (CuFe2S3). From the metallurgical method, the recovery of high economic value metals such as Pb, Zn and Cu is carried out, releasing to the environment waste ground material commonly called "tailings" enriched in gangue minerals that do not represent any economic interest for its exploitation as: pyrite (FeS2), arsenopyrite (FeAsS), pyrrhotite (Fe(1-x) S), calcite (CaCO3), quartz (SiO2) and K feldspars (AlSi3O8) [3, 18].

Once the deposition of tailings is concluded, either if oxygen and water flow through pores or if there is ferric ion, oxidation of sulfides occur, generating acidity through the release of protons H+ (Eqs. (7)–(10)]. In deposit of tailings, As is associated with pyrite, Zn and Cd with sphalerite, and they are released when these minerals are dissolved. Despite that galena has a reactivity similar sphalerite, it does dissolve very slowly because secondary mineral of anglesite (PbSO4) generally precipitates on its edges, which avoid its dissolution even in highly oxidized environments removed from sphalerite. Cu in acidic environments is released from chalcopyrite, while Co and Ni are generally derived from the oxidation of pyrite and pyrrhotite [3, 9].

$$\text{FeS}\_{2(s)} + \text{3.5O}\_{2(ac)} + H\_2\text{O}\_{(l)} \to \text{Fe}^{2+}\_{(ac)} + 2\text{SO}\_4^{2-} + 2\text{H}^+\_{(ac)}\tag{7}$$

$$\text{ZnS}\_{(s)} + \text{2O}\_{2(ac)} \rightarrow \text{Zn}^{2+}\_{(ac)} + \text{SO}^{2-}\_{4(ac)}\tag{8}$$

$$\text{PbS}\_{(s)} + \text{2O}\_{2(ac)} \rightarrow \text{Pb}^{2+}\_{(ac)} + \text{SO}^{2-}\_{4(ac)}\tag{9}$$

$$\text{FeS}\_2 + \text{14Fe}^{3+}\_{(ac)} + \text{8H}\_2\text{O}\_{(l)} \rightarrow \text{15Fe}^{2+}\_{(ac)} + \text{2SO}\_4^{2-} + \text{16H}^+\_{(ac)}\tag{10}$$

If the oxidation of sulfides remains, the acidity would increase at pH <4, generating acid mine drainage (AMD). However, if the mineralogy of the encasing rock has enough carbonate as calcite (CaCO3), hydroxide and silicate, when dissolution occurs, acid is consumed and neutralization of the AMD is completed [Eq. (11)], originating secondary gypsum precipitates and other metal sulfates [9, 11].

$$\text{CaCO}\_{3\text{ (s)}} + \text{H}\_2\text{SO}\_{4\text{ (ac)}} + \text{H}\_2\text{O}\_{(l)} \to \text{CaSO}\_4 \cdot 2\text{H}\_2\text{O}\_{(s)} + \text{CO}\_2\text{}\_{(g)}\tag{11}$$

However, when acidity-consuming minerals are insufficient, neutralization is not achieved, so continuous generation of AMD dissolves mineral phases, causing supersaturation of ions with high electrical conductivity and generating the precipitation of secondary minerals such as oxyhydroxides of Fe3+ (goethite), hydroxysulfates (jarosite, scorodite and beudantite). Those highly oxidized tailings, are rich in sulfides; the precipitation of these minerals' forms cemented layers known as hardpads, of low porosity and high density that serve as hydraulic barriers and temporary sinks of metals and metalloids, where the precipitation of beudantite and scorodite limits the mobility of As and Pb, and Fe oxyhydroxides adsorb Cd, Pb, Cr, Zn (despite their high mobility) and As where substitution process in jarosite is common [3, 6, 8]. Although Fe oxyhydroxides have a high adsorption capacity for highly toxic metals, it decreases as increasing crystallinity, the larger grain size the lower surface area. Although high concentrations of metals and metalloids reach the aquatic environment by runoff, their mobility will depend on the nature of the sediments and minerals that predominate in the aquatic environment [9].


**3. Dengue fever epidemiology**

Dengue is a viral mosquito-borne infection which in recent years has become a major international public health concern. According to the estimates given by (PDVI, 2011), 3.6 billion (55% of world population) are at risk of acquiring dengue infection (see Fig. 8a)). It is estimated that every year, there are 70 − 500 million dengue infections, 36 million cases of dengue fever (DF) and 2.1 million cases of dengue hemorragic fever (DHF), with more than 20.000 deaths per year (CDC, 2011; PDVI, 2011; WHO, 2009). In many countries in Asia and South America DF and DHF has become a substantial public health concern leading to serious social-economic costs.

Fig. 8. Worldwide Dengue distribution 2010. In red Countries and areas where dengue has been reported Data source: World Health Organization (WHO) & Centers for Disease Control and Prevention (CDC). Adapted from (Gubler, 2002; Mackenzie et al., 2004).

Dengue fever is transmitted by the female domestic mosquito Aedes aegypti, although Ae. albopictus and Ae. polynesiensis can also act as transmission vector (Favier et al., 2005). Virus transmission in its simplest form involves the ingestion of viremic blood by mosquitoes and passage to a second susceptible human host. The mosquito becomes infected when taking a blood meal from a viremic person. After an extrinsic incubation period, the mosquito becomes infective and remains so during its entire life span (Rigau-Pérez et al., 1998). As the blood meal stimulates ovoposition, which undergoes at least one, often more, reproductive cycles there is an opportunity of vertical transmission to the eggs, passing the virus to the next generation of mosquitoes (CDC, 2011; Monath, 1994; Rosen et al., 1983).

There are four antigenically distinct dengue viruses, designated DEN-1, DEN-2, DEN-3, and DEN-4 (Guzmán et al., 2010; Halstead, 1994; SES, 2010; WHO, 2009). Infection by one serotype confers life-long immunity to only that serotype and a short temporary cross-immunity period to other serotypes exists. It lasts from three to nine months, when the antibody levels created during the response to that infection would be enough to protect against infection by a different but related serotype (Dejnirattisai et al., 2010; Halstead, 1994; Matheus et al., 2005; SES, 2010; WHO, 2009). Two variants of the disease exist: dengue fever (DF), a non-fatal form 10 Will-be-set-by-IN-TECH

framework for epidemiological systems, is still the SIR type model, a good and simple model for many infectious diseases. However, different extensions of the classical single-strain SIR model show a rich dynamic behavior, e.g. (Stone et al., 2007) in measles, or in generalized multi-strain SIR type models to describe the epidemiology of dengue fever (Aguiar et al.,

Dengue is a viral mosquito-borne infection which in recent years has become a major international public health concern. According to the estimates given by (PDVI, 2011), 3.6 billion (55% of world population) are at risk of acquiring dengue infection (see Fig. 8a)). It is estimated that every year, there are 70 − 500 million dengue infections, 36 million cases of dengue fever (DF) and 2.1 million cases of dengue hemorragic fever (DHF), with more than 20.000 deaths per year (CDC, 2011; PDVI, 2011; WHO, 2009). In many countries in Asia and South America DF and DHF has become a substantial public health concern leading to serious

Fig. 8. Worldwide Dengue distribution 2010. In red Countries and areas where dengue has been reported Data source: World Health Organization (WHO) & Centers for Disease Control and Prevention (CDC). Adapted from (Gubler, 2002; Mackenzie et al., 2004).

Dengue fever is transmitted by the female domestic mosquito Aedes aegypti, although Ae. albopictus and Ae. polynesiensis can also act as transmission vector (Favier et al., 2005). Virus transmission in its simplest form involves the ingestion of viremic blood by mosquitoes and passage to a second susceptible human host. The mosquito becomes infected when taking a blood meal from a viremic person. After an extrinsic incubation period, the mosquito becomes infective and remains so during its entire life span (Rigau-Pérez et al., 1998). As the blood meal stimulates ovoposition, which undergoes at least one, often more, reproductive cycles there is an opportunity of vertical transmission to the eggs, passing the virus to the next generation of

There are four antigenically distinct dengue viruses, designated DEN-1, DEN-2, DEN-3, and DEN-4 (Guzmán et al., 2010; Halstead, 1994; SES, 2010; WHO, 2009). Infection by one serotype confers life-long immunity to only that serotype and a short temporary cross-immunity period to other serotypes exists. It lasts from three to nine months, when the antibody levels created during the response to that infection would be enough to protect against infection by a different but related serotype (Dejnirattisai et al., 2010; Halstead, 1994; Matheus et al., 2005; SES, 2010; WHO, 2009). Two variants of the disease exist: dengue fever (DF), a non-fatal form

mosquitoes (CDC, 2011; Monath, 1994; Rosen et al., 1983).

2008).

**3. Dengue fever epidemiology**

social-economic costs.

of illness, and dengue hemorrhagic fever (DHF), which may evolve toward a severe form known as dengue shock syndrome (DSS).

Epidemiological studies support the association of DHF with secondary dengue infection (Guzmán et al., 2000; Halstead, 1982, 2003; Nisalak et al., 2003; Vaughn, 2000), and there is good evidence that sequential infection increases the risk of developing DHF, due to a process described as antibody-dependent enhancement (ADE), where the pre-existing antibodies to previous dengue infection cannot neutralize but rather enhance the new infection.

Fig. 9. Scheme of the immunological response on recurrent dengue infections. In (a.) the first infection with a given dengue virus serotype, in (b.) production of antibodies (Immunoglobulin M (IgM)), in (c.) inactivation of the virus and in (d.) production of antibodies (IgG class, the so called memory antibodies). In (e.) the temporary cross immunity period, that lasts between 3-9 months. After that period, the individual can get infected again with another dengue virus serotype (f.). In (g.) the IgG from the previous dengue infection binds to the new virus but do not inactivate them. In (h.) the complex antibody-virus enhances the new infection (i.). In (j.) the production of antibodies (IgM class) which is then able to inactivate the new viruses, leading to (l.), an enhanced immune response, such that hemorrhagic symptoms are observed. In (m.) production of IgG antibodies.

In the first dengue infection virus particles will be captured and processed by so-called antigen presenting cells. These viruses will be presented to T-cells causing them to become activated. And likewise B-cells will encounter their antigen free floating and become activated. B-cells produce antibodies that are used to tag the viruses to encourage their uptake by macrophages and inactivate them. In a secondary infection the antibodies from the first infection will attach to the virus particles but will not inactivate them. The antibody-virus complex suppresses innate immune responses, increasing intracellular infection and generating inflammatory citokines and chemokines that, collectively, result in enhanced disease (Dejnirattisai et al., 2010; Guzmán et al., 2010; Halstead, 1982, 1994, 2003; Mackenzie et al., 2004; WHO, 2009). Fig.9 is an scheme to illustrate the immunological response on recurrent dengue infections.

DF is characterized by headache, retro-orbital pain, myalgia, arthralgia, rash, leukopenia, and mild thrombocytopenia. The symptoms resolve after 27 days. DHF is a potentially

(*R*).

infection was caused by strain two (*I*21) or for second time infected with strain two when the first infection was caused by strain one (*I*12). Notice that infection by one serotype confers life-long immunity to that serotype. Then the individuals recover from the secondary infection

Modeling Infectious Diseases Dynamics: Dengue Fever, a Case Study 241

To capture differences in primary infection by one strain and secondary infection by another strain we consider a basic two-strain SIR-type model for the host population, which is only slightly refined as opposed to previously suggested models for dengue fever (Billings et al.,

The stochastic version of the multi-strain dengue model is now in complete analogy to the previously described SIR model, and the mean field ODE system for the multi-strain dengue model can be read from the following reaction scheme (24), describing the transitions for first infection with strain 1 and secondary infection with strain 2, and for the reverse process, where the first infection is caused by strain 2 and the secondary infection is caused by strain 1, the

> *β* −→ *I*1 + *I*1

*φβ* −→ *I*1 + *I*21

*β* −→ *I*12 + *I*2

*φβ*

of two strains completely (for more information on the deterministic ODE system and its

The complete system of ordinary differential equations for the two strain epidemiological system is given by Eq. system (25) and the dynamics are described as follows. Susceptibles to both strains can get the first infection with strain one or strain two with force of infection *βI*

is acquired via an individual in his second infection. They recover from the first infection with a recovery rate *γ*, conferring full and life-long immunity against the strain that they were exposed to, and also a short period of temporary cross-immunity *α* against the other strain, becoming susceptible to a second infection with a different strain. The susceptible with

on whom (individual on his primary or secondary infection) is transmitting the infection. Then, with recovery rate *γ*, the individuals recover and become immune against all strains. We assume no epidemiological asymmetry between strains, i.e. infections with strain one or strain two contribute in the same way to the force of infection. Here, the only relevant difference concerning disease transmissibility is that the force of infection varies accordingly to the number of previous infections the hosts have experienced. The parameter *φ* in our model, is the ratio of secondary infection contribution to the force of infection. For more

−→ *I*12 + *I*12

*R*1 *α* −→ *S*1 (24)

−→ *S* defining the system

*N* when the infection

*N* depending

*N* or *φβI*

*N*

same reaction scheme can be used to describe the transitions by just changing labels.

*S* + *I*1

*S* + *I*21

*S*1 + *I*2

*S*1 + *I*12

The demographic transitions are *S*, *I*1, *I*2, *R*1, *R*2, *S*1, *S*2, *I*12, *I*21, *R μ*

when the infection is acquired via an individual in his first infection or *φβI*

a previous infection gets the secondary infection with force of infection *βI*

parametrization, see (Aguiar et al., 2011 a)).

*I*12 *γ* −→ *R*

*I*1 *γ* −→ *R*1

2007; Ferguson et al., 1999; Schwartz et al, 2005).

deadly complication that is characterized by high fever and hemorrhagic phenomenae. DHF develops rapidly, usually over a period of hours, and resolves within 12 days in patients who receive appropriate fluid resuscitation. Otherwise, it can quickly progress to shock (CDC, 2011; WHO, 2009).

Treatment of uncomplicated dengue cases is only supportive, and severe dengue cases requires careful attention to fluid management and proactive treatment of hemorrhagic symptoms (CDC, 2011; WHO, 2009). A vaccine against dengue is not yet available, since it would have to simulate a protective immune response to all four serotypes (Stephenson, 2005), although several candidates of tetravalent vaccines are at various stages of development (WHO, 2011).

Mathematical models describing the transmission of dengue viruses appeared in the literature early as 1970 (Fischer & Halstead, 1970). More recently, mathematical models describing the transmission of dengue viruses have focused on the ADE effect and temporary cross immunity trying to explain the irregular behavior of dengue epidemics. Such models ultimately aim to be used as a predictive tool with the objective to guide the policies of prevention and control of the dengue virus transmission, including the implementation of vaccination programs when the candidate dengue fever vaccines will be accessible. In the literature the multi-strain interaction leading to deterministic chaos via ADE has been described previously, e.g. (Billings et al., 2007; Ferguson et al., 1999; Schwartz et al, 2005) but neglecting temporary cross immunity. Consideration of temporary cross immunity is rather complicated and up to now not in detail analyzed. Models formulated in (Loureço & Recker, 2010; Nagao & Koelle, 2008; Recker et al., 2009; Wearing & Rohani, 2006), did not investigate closer the possible dynamical structures. In (Aguiar & Stollenwerk, 2007; Aguiar et al., 2008, 2009, 2011 a) by including temporary cross immunity into dengue models with ADE, a rich dynamic structure including deterministic chaos was found in wider and more biologically realistic parameter regions.


**3.1 Fused deposition modelling**

Fused deposition modelling (FDM) or known as fused filament fabrication (FFF) is a manufacturing technology in which objects are created by extruding polymer filament onto a built platform through a heated nozzle. There are numerous versions of FDM printers with various price ranges. In this research, Prusa i3 MK3 is used as a low-cost FDM printer where the platform moves in the Y-axis and the nozzle in the X- and Z-axes. When one layer is done, the nozzle will move up vertically to allow a new layer to be applied to the previous one. The thickness of the layer (slice) depends on the print parameters, and in the case of the used Prusa printer, the slices are between 0.05 and 0.30 mm thick [29]. Prior to the AM process, the constructed CAD model must be exported in a compatible file format, such as STL. Such a model is then cut into horizontal slices in a software package (so-called slicer). The paths of the platform and the nozzle are calculated by the software according to the parameters set by the user. In addition to the mentioned layer thickness, which significantly affects the accuracy, some of the other variable parameters are the number of layers in the outer wall and the number of layers at the bottom and top of the part, the percentage and structure of the filling, extrusion speed, and others. Because the next printing layer prints on top of the last one, supporting structures are required to print large overhangs or holes. They are printed together with the part and removed after printing is done. In general, overhangs should be avoided by proper orientation of the part or by using angled overhangs where possible. The most common materials used in FDM technology are ABS, PLA, PC, ASA, PPSF/PPSU, ULTEM, PH-HD. PE-LD, PET, TPU, and others. **Figure4** shows a working principle of the FDM technology.

### *3.1.1 Continuous fibre fabrication*

In addition to classic FDM technology, devices that can produce parts from composite materials using FDM processes are known as continuous fibre fabrication (CFF). In this paper, Markforged Onyx Pro is used, in which the platform moves in the Z-axis and the nozzle in the X- and Y-axes. Compared to the Prusa printer, it is a much more expensive device but allows 3D printing of composite materials made of plastic matrix and inlaid

*Framework for Design and Additive Manufacturing of Specialised Multirotor UAV Parts DOI: http://dx.doi.org/10.5772/intechopen.102781*

**Figure 5.** *Fibre reinforcement layout—CFF technology [30].*

fibreglass fibres for better mechanical properties and increased lifetime, compared to plastic alone. The strength and stiffness of a fibre-reinforced part can be comparable to aluminium. The software package allows adjustment of the classic print parameters and further adjustment of the composite reinforcements parameters as shown in **Figure 5**.


**About the Editors**

**Alberto Campisano**, Ph.D., Associate Professor, Associate Professor at the University of Catania since 2014. He has been an Assistant Professor at the same university since 2001. He is a qualified Civil engineer with a Ph.D. degree in Hydraulic Engineering from the University of Naples, Italy. He has 20 years of teaching and research experience in the field of water engineering. His teaching experience includes courses in hydraulic constructions, hydrology, and river engineering. His research activities include design, modeling and control of urban water systems, hydrology of natural and urban catchments, modeling of sediment transport in river and drainage systems, reservoir sedimentation, design of sediment control structures in rivers, sustainable urban drainage, rainwater harvesting systems. He is an author of more than 150 papers published in scientific journals and books, national and international conferences, author of books and manual chapters. He has been the supervisor of more than 70 diploma and master theses, and 8 Ph.D. theses in the field of hydraulic engineering. Research consultant for municipalities and other public institutions for problems related to water engineering. He has been chairman of the IWA/IAHR Urban Stormwater Harvesting Working Group.

**Enrico Creaco**, Ph.D., Associate Professor, Enrico Creaco obtained his Ph.D. in Hydraulic Engineering in 2006 and has researched topics pertinent to water and environmental systems for over ten years. His career began at the Universities of Catania and then Ferrara, Italy. From May 2014 to June 2015, he took up a Research Fellow post at the University of Exeter and became an Assistant Professor at the University of Pavia in September 2015. He has been an Associate Professor at the University of Pavia since September 2018. He has been Honorary Senior Reseach Fellow at the University of Exeter and Adjunct Senior Lecturer at the University of Adelaide. In September 2018, he obtained the Full Professor Qualification in the Hydraulics, Hydrology and Hydraulic Infrastructure Sector. He has been a lecturer on hydraulic infrastructures at both undergraduate and postgraduate levels and has published more than 100 papers in a variety of Scopus and ISI indexed international journals. He is the Associate Editor of the Journal of Water Resources Planning and Management—ASCE and participated in/coordinated various national and international research projects. Research interests: design and management of water distribution; sewer and irrigation systems; numerical modeling of shallow waters and sediment transport; demand analysis; protection of water distribution systems from contamination.


**1. Introduction**

As diverse as laser applications are, they have one thing in common: the complexity of the interaction of photons with matter and the multiphysics nature of the phenomena (thermal, fluidic, optical, mechanics, etc.) involved during laser processing whether it is drilling [1], grooving [2], cutting [3], welding [4], estimating ablation threshold limits [5] or simply predicting the thermal effects on the material [6]. Several mechanisms can be involved before, during and after the material ejection and they strongly depend on the laser characteristics (wavelength, pulse duration, beam shape, polarization, etc.) and the process parameters (scanning speed, repetition rate, pulse energy, etc.). The development in computer sciences (calculation capability and software) gave the opportunity to better understand the prepon‐ derance or the concomitance of mechanisms depending on the application and the objective of the researcher. Moreover, given the dynamic and short time-scale nature of the laser

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

process, numerical simulation can give an insight of what is happening inside the work‐ piece, which is delicate by experimental means.

Multiphysics packages such as ANSYS, ABAQUS, ADINA, or COMSOL are effective for the aforementioned issue and for fundamental investigation. In the industry, another semiempir‐ ical modeling method is useful when direct answers are expected regarding parameters optimization, predicting the system behavior or analyzing the effect of a modification. The Design Of Experiment (DOE) methodology shows its efficiency especially when the experi‐ mental investigation suffers from constraints such as the availability of the device, the experimenter, the material, the risks, the costs, or the environment.

Although nonexhaustive, a list of laser applications and how they were modeled will be presented in the following parts. Multiphysics models will be presented first, followed by the DOE approach. A laser application will be discussed for both types of numerical simulations.


**4. Summary**

The conducted study clarified that there is a clear influence of initiation behavior of the drawn arc on the electrode temperature, which is about 100 K (8%) higher in case of outer radial position measured directly after current interruption. Cr vapor density after current interruption is about 10% higher for outer radial positions. Therefore, it can be concluded that arc ignition in outer regions leads to higher local anode temperature and mean vapor density. Such behavior could potentially lead to increased electrode erosion, shorter lifetimes, and more restrikes (breakdown after current interruption). Future electrode design should take into account possible changes in electrode surface topology after significant current load.

Further investigations are planned to study the dependence of obtained results on material (electrode composition), as well other electrode design (such as AMF contacts).

**Author Contributions:** Conceptualization, S.G., A.L., E.D.T., F.G.; methodology, S.G., R.M., S.F.; software, S.F., S.G.; validation, E.D.T., F.G.; formal analysis, S.G.; investigation, S.G., D.G.; resources, D.G.; data curation, S.G.; writing—original draft preparation, S.G.; writing—review and editing, S.F., R.M., D.G., A.L., E.D.T. and F.G.; visualization, S.G., R.M. and S.F.; supervision, D.G. and F.G.; project administration, S.G. and A.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.