Characterization of surface and bulk features of SLM parts

An experiment-analytical procedure based on the building of an object in severe atmosphere resistant steel by SLM is proposed. The complex shape was investigated with the sectioning and laboratory observation of the physical object. The study evidenced the need to get a variable layer thickness to follow double curvature complex shapes. In particular the key variable in the process is the melt bath dimension by which the metal powder assumes by solidification the required global geometry. It was observed that the bath detected mainly in terms of the area of section tends to decrease when approaching to the surface of the physical model where the complex geometry needs to be described. Relationships describing the bath area behaviour and correlations between surface roughness and internal bath dimensions were found and proposed in detail. The surface roughness is highly correlated with the bath area in the zones of the section approaching the surface

in process control of rotational speed in friction stir welding of sheet blanks with variable mechanical properties

Abstract In the present work, an adaptive control constraint system was applied in the friction stir welding of AA6082 aluminum alloy with the aim of tailoring the mechanical properties of the sheet blank to the subsequent forming processes. To this purpose, blanks in the solution heat-treated and artificially aged (T6), and in the annealed (O) conditions were welded according to a well defined layout. Such in-process control strategy was based on the variation of the controlled variable (rotational speed of the pin tool) in order to keep the measured one (vertical force) constant during the welding stage of the process. To this end, a preliminary investigation on the effect of the rotational speed, varying from 1000 to 2500 rpm, on the vertical force during FSW was performed. The capability of the proposed approach in friction stir welding sheet blanks with variable mechanical properties along the welding line was proven

Buckling behavior of 3D printed composite isogrid structures

Abstract Different 3D printed composite isogrid structures in polyamide reinforced with 20% in weight of short carbon fiber were manufactured by means of fused deposition modeling process. Six configurations were realized varying the rib width and the rib thickness of the structures. The isogrid panels were tested under compressive load in order to investigate the effect of geometric parameters on the buckling behavior, in terms of strength and specific strength. Different failure modes were identified, depending on geometric parameters: global and local buckling. Finally, optical microscopy was carried out in order to analyze the fractured ribs after buckling. It was demonstrated that the configurations which result in the highest strength are not the same of those providing the highest specific strength

Deformation behavior of pre-painted steel sheets

Abstract The present work aims at studying the tensile behaviour of a hot-dip galvanized Z100 steel sheet, coated with a silicone-modified polyester resin. To this purpose, the pre-painted steel sheet was subjected to interrupted tensile tests at different strain levels in order to evaluate the elongation capability of both paint coating and steel sheet. The occurrence of superficial damages on paint coating was detected and the damage evolution before the sample fracture was analyzed. Furthermore, the thinning of each layer of the pre-painted sheet was also evaluated as a function of strain levels. Before the onset of necking, the degree of thinning on the different layers is almost uniform, whilst, once the necking was reached, a noticeable reduction in the thickness of both paint and steel sheet can be observed in the central zone of tensile sample

Mapping of Yucca gloriosa invasion along Mediterranean coastal dunes using unmanned aerial vehicles (UAVs)

Invasive Alien Plants (IAPs) are defined as those species whose introduction and/or spread outside their natural distribution can threaten the biological diversity of an ecosystem. They represent a severe threat to biodiversity and can severely alter the performance of crucial ecosystems such as coastal dunes. Coastal dunes are composed of specialized fauna and flora, converting them into strategic ecosystems due to their unique ecological functions. Coastal dunes are one of the most invaded European environments, with a total flora composed of up to 7% of IAPs. One of these IAPs is Yucca gloriosa L. (Asparagaceae), a homoploid hybrid native plant from the United States of America introduced to Europe for ornamental purposes. For Italy, Y. gloriosa is a typical invasive species related to fixed dunes dominated by Juniperus sp. pl. (with which it competes). Concerning biological invasions, maybe the most effective management strategy is early detection and mapping. In that sense, this work explores and tests the potential of unmanned aerial vehicles (UAVs) for detecting, mapping, and managing the Y. gloriosa invasion along the Mediterranean coastal dunes of a protected area located in Tuscany (Italy). In detail, this work focuses on four aspects: i) determine the suitability of RGB images to map Y. gloriosa, ii) identify the best time of data acquisition, iii) detect changes affecting the occurrence and cover of Y. gloriosa, and iv) propose a set of management actions to preserve a coastal dune ecosystem subjected to plant invasion. The UAV images allowed the generation of ultra-high spatial resolution maps to assess the Y. gloriosa invasion and distribution along the surveyed sandy dunes. The morphological characteristics of this plant – especially at the foliar level – make the invasion of Y. gloriosa particularly suitable for being evaluated and managed using UAV mapping, especially in coastal dunes vegetation that can be a mosaic of different plant communities hard to identify when airborne or satellite images are used. According to the obtained results, the spring season is the perfect time to collect data because light conditions are ideal, with minimal shading effects. Also, due to the peculiar morphology of Y. gloriosa leaves, the timing of data collection seems not crucial for mapping this IAP on coastal dune habitats. Despite the massive eradication action funded by a LIFE project during the period 2005-2009, Y. gloriosa is still present in the protected area and affects the priority habitat of juniper. This might be linked to the fact that Y. gloriosa is a perennial rhizomatous shrub capable of switching its photosynthesis from the C3 to CAM pathway and, therefore, withstand the harsh environmental conditions of dune ecosystems. The early detection using UAVs is the first line of defense against IAPs colonization over any ecosystem. From a conservation and management point of view, this work suggests the development of annual biomonitoring of Y. gloriosa to check its distribution over time and control its spread where it becomes particularly invasive. In this case, one possible strategy will be to keep the IAP in isolated nuclei of plants that are easier to remove with mechanical methods. In a broader view, the study area and the Mediterranean coast must include the ban on introducing non-native species as a strategy, adopting a short-term non-native Management Plan as urgent action

Impaired bone remodeling in children with osteogenesis imperfecta treated and untreated with bisphosphonates: the role of DKK1, RANKL, and TNF-α

In this study, we investigated the bone cell activity in patients with osteogenesis imperfecta (OI) treated and untreated with neridronate. We demonstrated the key role of Dickkopf-1 (DKK1), receptor activator of nuclear factor-κB ligand (RANKL), and tumor necrosis factor alpha (TNF-α) in regulating bone cell of untreated and treated OI subjects. These cytokines could represent new pharmacological targets for OI. Introduction: Bisphosphonates are widely used in the treatment of children with osteogenesis imperfecta (OI) with the objective of reducing the risk of fractures. Although bisphosphonates increase bone mineral density in OI subjects, the effects on fracture incidence are conflicting. The aim of this study was to investigate the mechanisms underlying bone cell activity in subjects with mild untreated forms of OI and in a group of subjects with severe OI treated with cycles of intravenous neridronate. Methods: Sclerostin, DKK1, TNF-α, RANKL, osteoprotegerin (OPG), and bone turnover markers were quantified in serum of 18 OI patients (12 females, mean age 8.86 ± 3.90), 8 of which were receiving cyclic intravenous neridronate, and 21 sex- and age-matched controls. The effects on osteoblastogenesis and OPG expression of media conditioned by the serum of OI patients and anti-DKK1 neutralizing antibody were evaluated. Osteoclastogenesis was assessed in cultures from patients and controls. Results: DKK1 and RANKL levels were significantly increased both in untreated and in treated OI subjects with respect to controls. The serum from patients with high DKK1 levels inhibited both osteoblast differentiation and OPG expression in vitro. High RANKL and low OPG messenger RNA (mRNA) levels were found in lymphomonocytes from patients. High amounts of TNF-α were expressed by monocytes, and an elevated percentage of circulating CD11b-CD51/CD61+ osteoclast precursors was observed in patients. Conclusions: Our study demonstrated the key role of DKK1, RANKL, and TNF-α in regulating bone cell activity of subjects with OI untreated and treated with bisphosphonates. These cytokines could represent new pharmacological targets for OI patients

β2-Adrenergic receptor stimulation improves endothelial progenitor cell-mediated ischemic neoangiogenesis

Endothelial progenitor cells (EPCs) are present in the systemic circulation and home to sites of ischemic injury where they promote neoangiogenesis. β2-Adrenergic receptor (β2AR) plays a critical role in vascular tone regulation and neoangiogenesis

The Results of the URRAH (Uric Acid Right for Heart Health) Project: A Focus on Hyperuricemia in Relation to Cardiovascular and Kidney Disease and its Role in Metabolic Dysregulation

The relationship between Serum Uric Acid (UA) and Cardiovascular (CV) diseases has already been extensively evaluated, and it was found to be an independent predictor of all-cause and cardiovascular mortality but also acute coronary syndrome, stroke and heart failure. Similarly, also many papers have been published on the association between UA and kidney function, while less is known on the role of UA in metabolic derangement and, particularly, in metabolic syndrome. Despite the substantial number of publications on the topic, there are still some elements of doubt: (1) the better cut-off to be used to refine CV risk (also called CV cut-off); (2) the needing for a correction of UA values for kidney function; and (3) the better definition of its role in metabolic syndrome: is UA simply a marker, a bystander or a key pathological element of metabolic dysregulation?. The Uric acid Right for heArt Health (URRAH) project was designed by the Working Group on uric acid and CV risk of the Italian Society of Hypertension to answer the first question. After the first papers that individuates specific cut-off for different CV disease, subsequent articles have been published responding to the other relevant questions. This review will summarise most of the results obtained so far from the URRAH research project

Serum Uric Acid Predicts All-Cause and Cardiovascular Mortality Independently of Hypertriglyceridemia in Cardiometabolic Patients without Established CV Disease: A Sub-Analysis of the URic acid Right for heArt Health (URRAH) Study

High serum uric acid (SUA) and triglyceride (TG) levels might promote high-cardiovascular risk phenotypes across the cardiometabolic spectrum. However, SUA predictive power in the presence of normal and high TG levels has never been investigated. We included 8124 patients from the URic acid Right for heArt Health (URRAH) study cohort who were followed for over 20 years and had no established cardiovascular disease or uncontrolled metabolic disease. All-cause mortality (ACM) and cardiovascular mortality (CVM) were explored by the Kaplan-Meier estimator and Cox multivariable regression, adopting recently defined SUA cut-offs for ACM (≥4.7 mg/dL) and CVM (≥5.6 mg/dL). Exploratory analysis across cardiometabolic subgroups and a sensitivity analysis using SUA/serum creatinine were performed as validation. SUA predicted ACM (HR 1.25 [1.12-1.40], p < 0.001) and CVM (1.31 [1.11-1.74], p < 0.001) in the whole study population, and according to TG strata: ACM in normotriglyceridemia (HR 1.26 [1.12-1.43], p < 0.001) and hypertriglyceridemia (1.31 [1.02-1.68], p = 0.033), and CVM in normotriglyceridemia (HR 1.46 [1.23-1.73], p < 0.001) and hypertriglyceridemia (HR 1.31 [0.99-1.64], p = 0.060). Exploratory and sensitivity analyses confirmed our findings, suggesting a substantial role of SUA in normotriglyceridemia and hypertriglyceridemia. In conclusion, we report that SUA can predict ACM and CVM in cardiometabolic patients without established cardiovascular disease, independent of TG levels

Serum uric acid and left ventricular mass index independently predict cardiovascular mortality: The uric acid right for heart health (URRAH) project

A relationship between serum uric acid (SUA) and cardiovascular (CV) events has been documented in the Uric Acid Right for Heart Health (URRAH) study. Aim: of this study was to investigate the association between SUA and left ventricular mass index (LVMI) and whether SUA and LVMI or their combination may predict the incidence of CV death. Methods: Subjects with echocardiographic measurement of LVMI included in the URRAH study (n=10733) were part of this analysis. LV hypertrophy (LVH) was defined as LVMI > 95 g/m2 in women and 115 g/m2 in men. Results: A significant association between SUA and LVMI was observed in multiple regression analysis in men: beta 0,095, F 5.47, P 5.6 mg/dl in men and 5.1 mg/dl in women) and LVH (log-rank chi-square 298.105; P<0.0001). At multivariate Cox regression analysis in women LVH alone and the combination of higher SUA and LVH but not hyperuricemia alone, were associated with a higher risk of CV death, while in men hyperuricemia without LVH, LVH without hyperuricemia and their combination were all associated with a higher incidence of CV death. Conclusions: Our findings demonstrate that SUA is independently associated with LVMI and suggest that the combination of hyperuricemia with LVH is an independent and powerful predictor for CV death both in men and women