Archivio Istituzionale della Ricerca - Università degli Studi della Campania "Luigi Vanvitelli"
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Numerical Fatigue Analysis for Crack Propagation Using XFEM Method
No full textAdditive manufacturing (AM) enables highly complex metallic components, but process-induced defects such as porosity, lack-of-fusion discontinuities, and residual stresses can markedly reduce fatigue resistance and accelerate crack initiation and growth. Because experimental fatigue crack propagation tests are costly, time-consuming, and not always transferable from standard specimens to real geometries, this dissertation develops a predictive numerical framework for fatigue crack growth in AM metals based on the eXtended Finite Element Method (XFEM). The work first establishes the fracture-mechanics background required to model fatigue crack growth, with emphasis on stress intensity factors and Paris-law behaviour. Building on this foundation, a mesh-independent XFEM formulation is implemented in Abaqus by combining enrichment functions, a partition-of-unity approach, and a level-set representation of the crack surface, enabling crack propagation without remeshing. Crack growth under cyclic loading is introduced through an energy-based fracture criterion, implemented via the *FRACTURE CRITERION keyword and calibrated using Paris-law constants, coupled with “Direct Cyclic” analyses to efficiently simulate large numbers of cycles. Validation is carried out in three stages. First, XFEM simulations of Compact Tension (CT) specimens are compared against experimental fatigue crack growth data, reproducing the crack-length evolution (a–N), fatigue crack growth rate trends, and Paris-law parameters with strong agreement. Second, the approach is tested against literature-based configurations including multiple-crack scenarios, demonstrating robustness in tracking complex crack paths. Finally, the framework is applied to a realistic AM component—a hip prosthesis stem—under service-like cyclic loading, comparing different material states (as-built versus post-processed conditions such as heat treatment and HIP) and showing the model’s capability to distinguish the influence of post-processing and load orientation on crack trajectory and predicted fatigue life
Pericolosi all'esercizio delle libertà democratiche: i fascisti nell'Italia repubblicana (1945-1960)
No full textThis research project investigates how democratic states have monitored, controlled, and repressed neo‐fascist groups after 1945, starting from the Italian case and extending to a broader European and transatlantic perspective. The core of the project is the analysis of intelligence services and exceptional legal tools such as police surveillance, preventive confinement, and special laws used against Italian neo‐fascists in the 1950s, in the context of the Cold War and of the consolidation of the republican constitutional order
Immunosenescence and Allergy: Molecular and Cellular Links Between Inflammaging, Neuro-Immune Aging, and Response to Biologic Therapies
No full textGenetic Editing of the zebrafish clock gene reveals previously unexpected molecular and phenotypic effects
No full textThe histone acetyltransferase (HAT) activity of the circadian protein CLOCK is thought to couple rhythmic transcription with chromatin remodeling, yet it in vivo function remains poorly understood. Here, we establish innovative zebrafish models to dissect the physiological relevance of CLOCKB acetyltransferase domain. Using CRISPR–Cas9 and base-editing approaches, we generated three complementary clockb mutant lines: a point mutation within the HAT domain (FEN), a complete knockout (CBKO), and in-frame deletion removing the entire HAT domain (INF). Loss of Clockb HAT function impaired histone H3 acetylation and disrupted circadian gene expression, demonstrating that Clockb is required to sustain rhythmic chromatin states. Beyond circadian control, clockb deficiency caused striking developmental alterations affecting eye formation, retinal organization, locomotor behavior, and pigment cell differentiation, revealing that Clockb acetyltransferase activity is essential for developmental homeostasis.At the systemic level, clockb mutants displayed consistent dysregulation of thyroid-axis genes, suggesting that Clockb links circadian chromatin regulation to endocrine signaling pathways controlling growth and pigmentation. Together, these findings identify Clockb as a chromatin-dependent regulator that synchronizes circadian transcription with endocrine and developmental programs. The zebrafish models developed here provide a unique in vivo platform to uncover how intrinsic HAT activity of circadian factors shapes vertebrate physiology
Biodegradable films enriched with thymol and carvacrol with antioxidant and antibacterial properties to extend cheese shelf-life
No full textBiodegradable active food packaging films obtained incorporating natural compounds, offer a promising solution for reducing food spoilage and prolonging shelf life. In this study, starch-based thermoplastic biopolymer (BioPol) was functionalized with thymol and carvacrol (at concentration of 5% and 8% wt/wt) through melting and mixing processes, producing flexible and sustainable films exhibiting both antioxidant and antimicrobial properties. To assess their effectiveness, these active films were used to package Brie cheese to evaluate their potential inextending its shelf life. The resulting flexible films were subjected to physico-chemical and thermal characterization, along with evaluation of their wettability and barrier properties. The results showed that incorporating carvacrol and thymol had minimal impact on the overall film properties, with the, exception of water vapor permeability. Specifically, films containing 5% and 8% thymol exhibited a reduction in water vapor permeability by approximately 29% and 22% for biopolymer (BioPol) films containing 5% and 8% thymol, respectively, compared to the unmodified biopolymer (BioPol). The functionalized films demonstrated effective scavenging of DPPH• and ABTS•+ radicals, achieving efficiencies greater than 50% and 90%, respectively. Films containing 8% carvacrol and thymol led to a microbial growth reduction of over 99.9% against pathogenic bacteria such as Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, and the spoilage bacterium Brochothrix thermosphacta, while Pseudomonas aeruginosa showed a growth reduction between 90 and 99%. Notably, when Brie cheese was wrapped in films containing 8% of the active compound, a strong antimicrobial effect (2 < R < 3) was observed against artificially inoculated pathogenic bacteria after 7 and 10 days of storage. In contrast, no antimicrobial activity was detected against lactobacilli
PRELIMINARY INSIGHTS INTO UNUSUAL PATHWAYS IN SENESCENCE: RNA LIGASE AND MITOCHONDRIAL MICROPROTEINS
No full textCellular senescence is a fundamental biological process that underlies
organismal aging and the emergence of degenerative disease. While conventional
models attribute senescence primarily to DNA damage, telomere erosion, and
oxidative stress, there is now evidence pointing toward additional, nonconventional
molecular pathways that sustain the senescent state. This thesis investigates two
pathways, including human RNA ligase (C12ORF29) and mitochondrial-derived
microproteins (MDPs) containing HUMANIN, SHLP2, and SHLP3 as novel cellular
stress response and senescence regulators in mesenchymal stromal cells (MSCs).
We found that C12ORF29 is significantly upregulated at both mRNA and
protein levels under oxidative stress and cellular senescence, suggesting its direct
involvement in maintaining RNA stability and ribosomal function under stressful
conditions. Knockdown of C12ORF29 with siRNA induced massive cell death in
senescent MSCs, suggesting its indispensable role in RNA stability and cellular
survival during stress adaptation.
Simultaneously, mitochondrial-derived microproteins were found to exhibit
both mitochondrial and cytoplasmic localization. Oxidative stress triggered the strong
upregulation of HUMANIN, SHLP2, and SHLP3 expression, as confirmed by
immunocytochemistry, Western blotting, and RT qPCR analysis of RNR1 and RNR2,
mitochondrial rRNA genes. Exogenous treatment with HUMANIN inhibited H2O2-
induced apoptosis, increased proliferation, restored normal cell cycle progression, and
reduced senescence-associated β-galactosidase activity. These findings confirm the
cytoprotective and anti-senescent activities of HUMANIN in maintaining
mitochondrial and cellular homeostasis.
Together, these results suggest that C12ORF29 and mitochondrial
microproteins act as cooperative factors within the cellular defence network, linking
RNA maintenance and mitochondrial signalling to stress resistance and longevity. The
study positions these molecules in the spotlight as potential biomarkers and
therapeutic targets for protection from oxidative damage and senescence-associated
dysfunction, offering new insight into the noncanonical molecular mechanisms of
aging
Innovative Dietary Strategies: A novel approach to Obesity management and diseases prevention
No full textAbstract
Obesity represents a major global health issue, associated with metabolic syndrome, insulin resistance, and chronic inflammation. Identifying effective and sustainable dietary strategies is essential for improving metabolic efficiency and reducing related comorbidities. Recent evidence highlights the role of Orexin-A, a hypothalamic neuropeptide regulating arousal, appetite, and energy expenditure, as a potential biomarker of neuro-metabolic adaptation. This study aimed to evaluate the effects of three different dietary interventions—low-calorie Mediterranean diet, intermittent fasting (16:8), and alternate-day fasting (5:2)—on body composition, metabolic parameters, inflammatory profile, and plasma Orexin-A levels in obese subjects. Thirty obese participants (15 males and 15 females, aged 20–40 years) were recruited from the Dietetics and Sports Medicine Unit of the University of Campania “Luigi Vanvitelli”. Subjects were divided into three groups (n=10 per group), each following one of the three dietary regimens for 12 months. Anthropometric parameters, lipid and glycemic profiles, and inflammatory cytokines (CRP, TNF-α, IL-6, IL-10) were measured at baseline (T0) and at 3-month intervals (T1, T2, T3). Plasma Orexin-A levels were quantified by ELISA. All dietary regimens improved body composition and metabolic health over time, but with distinct patterns. The 16:8 intermittent fasting protocol produced the most rapid and consistent benefits, including significant reductions in BMI, visceral fat, total cholesterol, and blood glucose, along with a marked increase in Orexin-A levels (p < 0.001). The low-calorie Mediterranean diet induced gradual improvements, becoming significant at T3, while the 5:2 fasting regimen produced modest, non-significant changes. The observed rise in Orexin-A correlated with enhanced metabolic flexibility and reduced inflammation, suggesting a neuroendocrine adaptation to time-restricted feeding. Among the dietary strategies tested, intermittent fasting (16:8) proved to be the most effective in improving metabolic efficiency, reducing inflammation, and increasing Orexin-A levels. These results support its potential as a practical and sustainable therapeutic approach for obesity management
