Precast CSA-based concrete tunnel lining segments reinforced with GFRP bars: challenges and opportunities

This research study investigates the potential of using Calcium Sulfoaluminate (CSA) binder as a sustainable alternative to ordinary Portland cement (OPC) in the production of precast concrete tunnel lining (PCTL) segments. The effectiveness of CSA-based concrete, reinforced with Glass Fiber-Reinforced Polymer (GFRP) bars, was examined through an experimental program. Comparative analyses, including analytical, experimental, and Life Cycle Assessment (LCA) comparisons, were conducted with OPC-based segments reinforced with traditional steel. The results indicate that the proposed CSA/GFRP solution has the potential to improve sustainability in mechanized tunnelling and prefabrication. A case study is also presented to support these findings

optimization of gfrp reinforcement in precast segments for metro tunnel lining

The possibility of replacing the traditional steel reinforcement with glass fiber reinforced polymer (GFRP) cages in precast concrete tunnel segmental lining has been shown by the authors in previous papers. The use of GFRP rebars as structural reinforcement in precast tunnel segments, allows several advantages in terms of structural durability or in cases of temporary lining that will have to be demolished later. Furthermore, this reinforcement type can be a suitable solution to create dielectric joints, ensuring the interruption of possible stray currents, which often lead to corrosion problems. Nevertheless, this peculiar application requires curvilinear shape of the reinforcement, and then different production process and rebar geometries. In the present work, a suggestion for the optimization of the GFRP reinforcement for tunnel segment is given. Four different GFRP cage typologies are analysed and applied as a reinforcement in full-scale tunnel segments. Both bending and point load tests are developed and the structural performances of the specimens are compared and discussed. Finally, the best solution, in terms of cost-benefit analysis is proposed

Experimental Test on Flexural Performance of Prestressed Concrete Beams Damaged by Corrosion

Prestressed reinforced concrete beams are widely used in industrial and commercial buildings, which are commonly exposed to aggressive environments and damaged by corrosion. This precast construction technique has also been used for the last 50 years in most viaducts and bridges built in many countries like Italy. According to previous literature results, the corrosion of prestressed concrete structures causes the size reduction of strands, degradation of mechanical properties of steel, cracking of the surrounding concrete and bond decay at the steel-to-concrete interface. The mixing of these effects strongly reduces the bearing-capacity of prestressed reinforced concrete members, changing the failure mechanism as well. In the framework of the OPTION research project between Niccolò Cusano University and Oslo Metropolitan University, an experimental campaign investigates the behavior of corroded prestressed beams. Four prestressed beams (cross section size 200 × 300; total length 3000 mm; clear span 2700 mm) were first subjected to artificial corrosion, to obtain different damage levels, and were then tested in four-point bending. The goal is to estimate the corrosion level that makes a deteriorated prestressed reinforced concrete beam less ductile while keeping the strength unchanged. In the present study, the first experimental results and some details about the laboratory procedure are presented

A multi-resolutive extraction of geometric descriptors for virtual shapes and humans

Tools for the automatic decomposition of a surface into shape features will facilitate and optimize the classification, matching, texturing, morphing, and simplification of 3D shapes. Different features, such as flats, limbs, tips, pits, and various blending shapes between them may be characterized in terms of local curvature and other differential properties of the surface, or in terms of a global skeletal organization of the volume it encloses. However, both solutions are extremely sensitive to small perturbations in the surface smoothness and to quantization effects when they operate on triangulated surfaces. The paper presents a shape characterization based on a multi-resolutive curvature computation where the vertices of a given triangle mesh are classified according to their curvature and shape behavior in neighborhoods of increasing size, and whose final goal is to segment 3D models into main bodies and tubular parts, and to code the tube/body connectivity with their geometric parameters. Last, we propose to apply the morphological analysis for the automatically extraction of the semantic of human body models for their representation, retrieval and applications to animation. We prove the efficacy of our tool in automatically extracting morphological shape parameters and locating feature points on the human body identifying fingertips, nose,armpits, ankles, umbilicus, and so on

3D Shape Matching through Topological Structures

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Multi-Segmentation and Annotation of 3D Surface Meshes

The ShapeAnnotator is a graphical tool designed to assist an expert user in the task of annotating a surface mesh with concepts belonging to a domain of expertise. The user is first required to identify meaningful surface features; Each such feature can then be "labeled" with a concept, and the surface mesh, along with the features identified and their labels, can be saved

Mapping genetic determinants of host susceptibility to Pseudomonas aeruginosa lung infection in mice.

Background: P. aeruginosa is one of the top three causes of opportunistic human bacterial infections. The remarkable variability in the clinical outcomes of this infection is thought to be associated with genetic predisposition. However, the genes underlying host susceptibility to P. aeruginosa infection are still largely unknown. Results: As a step towards mapping these genes, we applied a genome wide linkage analysis approach to a mouse model. A large F2 intercross population, obtained by mating P. aeruginosa-resistant C3H/HeOuJ, and susceptible A/J mice, was used for quantitative trait locus (QTL) mapping. The F2 progenies were challenged with a P. aeruginosa clinical strain and monitored for the survival time up to 7 days post-infection, as a disease phenotype associated trait. Selected phenotypic extremes of the F2 distribution were genotyped with high-density single nucleotide polymorphic (SNP) markers, and subsequently QTL analysis was performed. A significant locus was mapped on chromosome 6 and was named P. aeruginosa infection resistance locus 1 (Pairl1). The most promising candidate genes, including Dok1, Tacr1, Cd207, Clec4f, Gp9, Gata2, Foxp1, are related to pathogen sensing, neutrophils and macrophages recruitment and inflammatory processes. Conclusions: We propose a set of genes involved in the pathogenesis of P. aeruginosa infection that may be explored to complement human studie

Comparison of two strategies for the management of postoperative recurrence in Crohn's disease patients with one clinical risk factor: A multicentre IG-IBD study

BackgroundThe management of postoperative recurrence (POR) in Crohn's disease (CD) after ileo-colonic resection is a highly debated topic. Prophylactic immunosuppression after surgery is currently recommended in the presence of at least one clinical risk factor. ObjectiveOur aim was to determine whether early immunosuppression can be avoided and guided by endoscopy in CD patients with only one risk factor. MethodsCD patients with only one risk factor for POR, including previous intestinal resection, extensive small intestine resection (>50 cm), fistulising phenotype, history of perianal disease, and active smoking, were retrospectively included. Two groups were formed based on whether immunosuppression was started immediately after surgery ("prophylaxis group") or guided by endoscopy ("endoscopy-driven group"). Primary endpoints were rates of any endoscopic recurrence (Rutgeerts >= i2a) and severe endoscopic recurrence (i4) within 12 months after surgery. Secondary outcomes were clinical recurrence rates at 6, 12 and 24 months after surgery. ResultsA total of 195 patients were enroled, of whom 61 (31.3%) received immunoprophylaxis. No differences between immunoprophylaxis and the endoscopy-driven approach were found regarding any endoscopic recurrence (36.1% vs. 45.5%, respectively, p = 0.10) and severe endoscopic recurrence (9.8% vs. 15.7%, respectively, p = 0.15) at the first endoscopic evaluation. Clinical recurrence rates were also not statistically different (p = 0.43, p = 0.09, and p = 0.63 at 6, 12, and 24 months, respectively). ConclusionsIn operated CD patients with only one risk factor for POR, immediate immunoprophylaxis does not decrease the rate of early clinical and endoscopic recurrence. Prospective studies are needed to confirm our results

Frictional Melting in Hydrothermal Fluid-Rich Faults: Field and Experimental Evidence From the Bolfín Fault Zone (Chile)

Tectonic pseudotachylytes are thought to be unique to certain water-deficient seismogenic environments and their presence is considered to be rare in the geological record. Here, we present field and experimental evidence that frictional melting can occur in hydrothermal fluid-rich faults hosted in the continental crust. Pseudotachylytes were found in the >40 km-long Bolfín Fault Zone of the Atacama Fault System, within two ca. 1 m-thick (ultra)cataclastic strands hosted in a damage-zone made of chlorite-epidote-rich hydrothermally altered tonalite. This alteration state indicates that hydrothermal fluids were active during the fault development. Pseudotachylytes, characterized by presenting amygdales, cut and are cut by chlorite-, epidote- and calcite-bearing veins. In turn, crosscutting relationship with the hydrothermal veins indicates pseudotachylytes were formed during this period of fluid activity. Rotary shear experiments conducted on bare surfaces of hydrothermally altered rocks at seismic slip velocities (3 m s−1) resulted in the production of vesiculated pseudotachylytes both at dry and water-pressurized conditions, with melt lubrication as the primary mechanism for fault dynamic weakening. The presented evidence challenges the common hypothesis that pseudotachylytes are limited to fluid-deficient environments, and gives insights into the ancient seismic activity of the system. Both field observations and experimental evidence, indicate that pseudotachylytes may easily be produced in hydrothermal environments, and could be a common co-seismic fault product. Consequently, melt lubrication could be considered one of the most efficient seismic dynamic weakening mechanisms in crystalline basement rocks of the continental crust

Reduced humoral response to two doses of COVID-19 vaccine in patients with inflammatory bowel disease: Data from ESCAPE-IBD, an IG-IBD study

Background Patients on immunosuppressive drugs have been excluded from COVID-19 vaccines trials, creating concerns regarding their efficacy. Aims To explore the humoral response to COVID-19 vaccines in patients with inflammatory bowel disease (IBD) Methods Effectiveness and Safety of COVID-19 Vaccine in Patients with Inflammatory Bowel Disease (IBD) Treated with Immunomodulatory or Biological Drugs (ESCAPE-IBD) is a prospective, multicentre study promoted by the Italian Group for the study of Inflammatory Bowel Disease. We present data on serological response eight weeks after the second dose of COVID-19 vaccination in IBD patients and healthy controls (HCs). Results 1076 patients with IBD and 1126 HCs were analyzed. Seropositivity for anti-SARS-CoV-2 IgG was reported for most IBD patients, even if with a lesser rate compared with HCs (92.1% vs. 97.9%; p<0.001). HCs had higher antibody concentrations (median OD 8.72 [IQR 5.2-14-2]) compared to the whole cohort of IBD patients (median OD 1.54 [IQR 0.8-3.6]; p<0.001) and the subgroup of IBD patients (n=280) without any treatment or on aminosalicylates only (median OD 1.72 [IQR 1.0–4.1]; p<0.001). Conclusions Although most IBD patients showed seropositivity after COVID-19 vaccines, the magnitude of the humoral response was significantly lower than in HCs. Differently from other studies, these findings seem to be mostly unrelated to the use of immune-modifying treatments (ClinicalTrials.govID:NCT04769258)