Seismic cycle and deformation processes in quartz gouges under hydrothermal conditions

openMy master’s thesis project is focused on the study of the mechanical behavior of a quartz gouge during the seismic cicle (and the related deformation mechanisms) under hydrothermal conditions and in presence of hot and pressurized water. To achieve this purpose, I am exploiting the rotary shear apparatus “RoSA” equipped with the pressure vessel “Hydros” which is installed in the Rock Mechanics Laboratory of the Department of Geosciences. This machine allows to simulate the seismic cycle, applying an effective stress (σn’) to the analyzed samples and making the samples shear with temperatures (T) up to 500 °C and especially in the presence of pressurized fluids. Specifically, I performed 10 Slide-Hold-Slide (SHS) tests alternating slip phases (slide) with stationary contact phases (hold), to measure how a fault regains strength by increasing the stationary contact time (healing). This parameter is fundamental to describe the recurrence of seismic events within a fault. Five experiments were carried out with an F110 heterometric angular quartz, varying effective stress, fluid pressure (Pp) and temperature. The remaining 5 experiments instead were conducted using microquartz, replicating the same experimental conditions used before, to evaluate the different mechanical behavior as a function of the experimental parameters, such as σn’, Pp, T and grain size. The used experimental procedure consists in: 1. Sample preparation (usually 1.2-1.5 g of gouge) and assembly of the apparatus. 2. Achievement of the experimental parameters (σn’, Pp, T). 3. Wait for chemical equilibrium to be reached between fluids and sample (H2O and SiO2, usually 2 hours). 4. Initial shear, usually between 40 and 50 mm, at a velocity of 10 μm/s, to reach steady state in terms of shear torque and compaction. 5. SHS test, which includes a series of 1 mm slides alternating with increasing hold time (usually from 3 to about 50000 s), 6. New 10-15 mm slide. 7. Repeat the previous SHS series, in order to investigate the effect of strain on the mechanical response of the gouge. 8. Extraction of the sample from the apparatus. 9. Drying of the sample, ready for a microstructural/microanalytical analysis. The samples, which are initially powder, at the end of the experiments are slightly cohesive, allowing their correct extraction from the apparatus to analyze the produced microstructures. I have developed different Matlab codes to analyze the obtained mechanical data. Precisely, after some data cleaning steps including removal of outliers and smoothing, I am converting the measurements of the machine (shear torque, vertical displacement, rpm, etc.) into data with geological meaning such as friction, slip, compaction, etc. Once these values have been calculated, plotting them against each other is the way to visualize the different trends.My master’s thesis project is focused on the study of the mechanical behavior of a quartz gouge during the seismic cicle (and the related deformation mechanisms) under hydrothermal conditions and in presence of hot and pressurized water. To achieve this purpose, I am exploiting the rotary shear apparatus “RoSA” equipped with the pressure vessel “Hydros” which is installed in the Rock Mechanics Laboratory of the Department of Geosciences. This machine allows to simulate the seismic cycle, applying an effective stress (σn’) to the analyzed samples and making the samples shear with temperatures (T) up to 500 °C and especially in the presence of pressurized fluids. Specifically, I performed 10 Slide-Hold-Slide (SHS) tests alternating slip phases (slide) with stationary contact phases (hold), to measure how a fault regains strength by increasing the stationary contact time (healing). This parameter is fundamental to describe the recurrence of seismic events within a fault. Five experiments were carried out with an F110 heterometric angular quartz, varying effective stress, fluid pressure (Pp) and temperature. The remaining 5 experiments instead were conducted using microquartz, replicating the same experimental conditions used before, to evaluate the different mechanical behavior as a function of the experimental parameters, such as σn’, Pp, T and grain size. The used experimental procedure consists in: 1. Sample preparation (usually 1.2-1.5 g of gouge) and assembly of the apparatus. 2. Achievement of the experimental parameters (σn’, Pp, T). 3. Wait for chemical equilibrium to be reached between fluids and sample (H2O and SiO2, usually 2 hours). 4. Initial shear, usually between 40 and 50 mm, at a velocity of 10 μm/s, to reach steady state in terms of shear torque and compaction. 5. SHS test, which includes a series of 1 mm slides alternating with increasing hold time (usually from 3 to about 50000 s), 6. New 10-15 mm slide. 7. Repeat the previous SHS series, in order to investigate the effect of strain on the mechanical response of the gouge. 8. Extraction of the sample from the apparatus. 9. Drying of the sample, ready for a microstructural/microanalytical analysis. The samples, which are initially powder, at the end of the experiments are slightly cohesive, allowing their correct extraction from the apparatus to analyze the produced microstructures. I have developed different Matlab codes to analyze the obtained mechanical data. Precisely, after some data cleaning steps including removal of outliers and smoothing, I am converting the measurements of the machine (shear torque, vertical displacement, rpm, etc.) into data with geological meaning such as friction, slip, compaction, etc. Once these values have been calculated, plotting them against each other is the way to visualize the different trends

Cities as development hubs in Italy an analytical approach

Italy, the country where the modern cities were born, suffer from the early '90 of past century for a lack of vision and political address in terms of adoption of its urban agenda. The public debate about cities is focused only on administrative and insti aspects; not enough attention is dedicated to the problems of the Italian cities as development hubs. As a result, the law of 2014 that introduced the formal regulation of new metropolitan authorities lies unapplied. The paper gives some evidence about the economic specialization of the most important Italian metropolitan cities and about their relative room for innovation, using an hirschmanian index

Support from Teaching Staff and Self-efficacy as Determinants of Students' Perceived Employability: a Longitudinal study

[EN] Perceived employability acquires, for university students, growing importanceto deal with occupational uncertainty. This study examines how teaching inuniversity influences perceived employability in a sample of Italian final-yearuniversity students. We draw on Conservation on Resources Theory andCareer self-management model to hypothesise a positive impact of supportfrom teaching staff on students' perceived employability. We also contend thatstudents' self-efficacy mediates the relationship between support from teachingstaff and perceived employability. One hundred fifty-one university studentscompleted a survey three times over 10 months. The results confirm thatsupport from teaching staff enhances students' perceived employabilitydirectly and indirectly by shaping students' self-efficacy. Our findings confirmthe role of university teachers and their didactical practice to equip theirstudents with career resources.Petruzziello, G.; Mariani, MG.; Guglielmi, D.; Chiesa, R. (2021). Support from Teaching Staff and Self-efficacy as Determinants of Students' Perceived Employability: a Longitudinal study. En 7th International Conference on Higher Education Advances (HEAd'21). Editorial Universitat Politècnica de València. 1079-1086. https://doi.org/10.4995/HEAd21.2021.12957OCS1079108

Serum mesothelin and other biomarkers: What have we learned in the last decade?

In the last decade there is been much interest in noninvasive, economic and well-accepted diagnostic tests for screening of subjects exposed to asbestos, and in patients with malignant pleuric mesothelioma (MPM) for diagnosis or monitoring response to treatment. Several biomarkers have been suggested as tools for screening and early diagnosis of MPM. Currently, in patients with MPM, have been reported high levels of soluble mesothelin-related peptides (SMRP), plasmatic osteopontin (pOPN), vimentin, fibulin-3 and many others as promising marker for diagnosis, even their use in prevention monitoring is still discussed. In this type of disease, a key role could be played by miRNAs, which expression has been investigated in a large series of MPM to examine new pathways useful in diagnosis, prognosis and therapy. An altered expression of some proteins has been reported, useful as biomarkers, in comparative proteomic analysis of malignant pleural mesothelioma. New promising markers are nowadays under study and alone or better in combination, they'll be very helpful in diagnosing, monitoring mesothelioma patients or for screening of risk groups

Imaging of Congenital Skeletal Disorders

AbstractOsteochondrodysplasias are the result of the expression of gene mutations. The phenotypes in osteochondrodysplasias evolve through life, with the possibility that previously unaffected bones may be involved at later stages of growth. Due to the variable time of onset, the diagnosis may be made prenatally, at birth, or later. Certainty in the diagnosis is sometimes only achieved as the patient matures and the disease evolves. Radiographic evaluation is a fundamental part of the diagnostic work-up of congenital skeletal disorders and in most cases the first tool used to arrive at a diagnosis. This review describes the imaging characteristics, specific signs, and evolution of several skeletal dysplasias in which diagnosis may be directly or indirectly suggested by radiologic findings. A definitive accurate diagnosis of a congenital skeletal abnormality is necessary to help provide a prognosis of expected outcomes and to counsel parents and patients

Biomarkers in the prevention and follow-up of workers exposed to asbestos

Although in most developed countries the use of asbestos is banned, there is still a consistent portion of the world where asbestos extraction, trading and manufacturing of asbestos-made products is largely diffuse. Worldwide, hundreds of millions of people are at risk of developing an asbestos caused disease because of occupational, environmental or domestic exposure. The WHO estimates that asbestos is responsible for more than 100,000 deaths yearly. This scenario has prompted the research on biomarkers potentially useful for early diagnosis, prognosis and preventive programs on exposed population as well. Here we reviewed the up-to-date literature on this field of research highlighting that along with mesothelin and osteopontin (OPN), some more recently investigated molecules, such as high mobility group box 1 (HMGB1) protein, fibulin-3 and some miRNAs showed very promising. Most of the carried-out studies showed an interesting diagnostic and prognostic performance of some biomarkers, but since they usually lack adequate either specificity or sensitivity, their use in screening or in preventive programs is still not recommended on a routine basis. However, this review suggests the need for more reliable experimental design involving larger population and preferring longitudinal screening of asbestos exposed individuals rather than a single baseline assessment investigation. In addition, given their better diagnostic accuracy, the use of panels including several biomarkers is highly recommended

Positive aging in demanding workplaces: The gain cycle between job satisfaction and work engagement

Nowadays organizations have to cope with two related challenges: maintaining an engaged and highly performing workforce and, at the same time, protecting and increasing employees' well-being and job satisfaction under conditions of a generalized increase of job demand, in an increasingly growing older population. According to the motivational process of the JD-R model, a work environment with many organizational resources will foster work engagement, which in turn will increase the likelihood of positive personal and organizational outcomes, such as job satisfaction, performance, and intention to stay. However, it is not clear how this motivational process could work in different age cohorts, as older workers may have different priorities to those of younger colleagues. Postulating the existence of a gain-cycle in the relationship between work engagement and outcomes, in this study we tested a longitudinal moderated mediation model in which job satisfaction increases over time through an increment in work engagement. We hypothesized that this process is moderated by job demand and aging. We collected data in public administrations in Northern Italy in order to measure work engagement and job satisfaction. 556 workers aged between 50 and 64 replied to the survey twice (the first time and 8 months later). The findings confirmed a moderated mediation model, in which job satisfaction at time 1 increased work engagement, which in turn fostered job satisfaction 8 months later, confirming the hypothesized gain-cycle. This relationship was shown to be moderated by the joint influence of job demand intensity and age: higher job demands and younger age are related to the maximum level of level gain cycle, while the same high level of job demands, when associated with older age, appears unable to stimulate a similar effect. The results confirm that, on one hand, older workers cannot be seen as a homogeneous group and, on the other hand, the importance of considering the role played by the gain cycle of resources. Our findings show that age matters, and that greater consideration should be devoted to age differences in order to design appropriate human resources practices that foster work engagement and satisfaction

Spaced out. Raccontare lo spazio con le immagini

Between si avventura nel campo, vasto e insidioso, dello studio dei fumetti. Lo fa dando spazio, per la progettazione e la cura di questo numero, alla collaborazione, attiva dal 2015 in questo ambito di ricerca, tra studiosi dell’Università di Cagliari, dell’Università di Bologna, dell’Université Paris Nanterre e dell’Accademia delle Belle Arti di Bologna. Nella condivisione di interessi, prospettive di studio e pratiche creative, i membri di questo piccolo sodalizio hanno tratto di che alimentare una vivace attività di ricerca e hanno saputo dare vita ad alcune importanti occasioni di incontro e di confronto dedicate al fumetto, come le giornate di studio Storie lievi, nel 2015 e nel 2016

Thermal-induced phase transitions in self-assembled mesostructured films studied by small-angle X-ray scattering

Two examples of phase transition in self-assembled mesostructured hybrid thin films are reported. The materials have been synthesized using tetraethoxysilane as the silica source hydrolyzed with or without the addition of methyltriethoxysilane. The combined use of transmission electron microscopy, small-angle X-ray scattering and computer simulation has been introduced to achieve a clear identification of the organized phases. A structural study of the self-assembled mesophases as a function of thermal treatment has allowed the overall phase transition to be followed. The initial symmetries of mesophases in as-deposited films have been linked to those observed in samples after thermal treatment. The monodimensional shrinkage of silica films during calcination has induced a phase transition from face-centered orthorhombic to body-centered cubic. In hybrid films, instead, the phase transition has not involved a change in the unit cell but a contraction of the cell parameter normal to the substrate