Adaptive search space decomposition method for pre- and post-buckling analyses of space truss structures

The paper proposes a novel adaptive search space decomposition method and a novel gradient-free optimization-based formulation for the pre- and post-buckling analyses of space truss structures. Space trusses are often employed in structural engineering to build large steel constructions, such as bridges and domes, whose structural response is characterized by large displacements. Therefore, these structures are vulnerable to progressive collapses due to local or global buckling effects, leading to sudden failures. The method proposed in this paper allows the analysis of the load-equilibrium path of truss structures to permanent and variable loading, including stable and unstable equilibrium stages and explicitly considering geometric nonlinearities. The goal of this work is to determine these equilibrium stages via optimization of the Lagrangian kinematic parameters of the system, determining the global equilibrium. However, this optimization problem is non-trivial due to the undefined parameter domain and the sensitivity and interaction among the Lagrangian parameters. Therefore, we propose to formulate this problem as a nonlinear, multimodal, unconstrained, continuous optimization problem and develop a novel adaptive search space decomposition method, which progressively and adaptively re-defines the search domain (hypersphere) to evaluate the equilibrium of the system using a gradient-free optimization algorithm. We tackle three benchmark problems and evaluate a medium-sized test representing a real structural problem in this paper. The results are compared to those available in the literature regarding displacement–load curves and deformed configurations. The accuracy and robustness of the adopted methodology show a high potential for gradient-free algorithms to analyze space truss structures

New Frontiers on Seismic Modeling of Masonry Structures

An accurate evaluation of the non-linear behavior of masonry structural elements in existing buildings still represents a complex issue that rigorously requires non-linear finite element strategies difficult to apply to real large structures. Nevertheless, for the static and seismic assessment of existing structures, involving the contribution of masonry materials, engineers need reliable and efficient numerical tools, whose complexity and computational demand should be suitable for practical purposes. For these reasons, the formulation and the validation of simplified numerical strategies represent a very important issue in masonry computational research. In this paper, an innovative macroelement approach, developed by the authors in the last decade, is presented. The proposed macroelement formulation is based on different, plane and spatial, macroelements for the simulation of both the in-plane and out-of-plane behavior of masonry structures also in presence of masonry elements with curved geometry. The mechanical response of the adopted macroelement is governed by non-linear zero-thickness interfaces, whose calibration follows a straightforward fiber discretization, and the non-linear internal shear deformability is ruled by equivalence with a corresponding geometrically consistent homogenized medium. The approach can be considered as "parsimonious" since the kinematics of the adopted elements is controlled by very few degrees of freedom, if compared to a corresponding discretization performed by using non-linear finite element method strategies. This innovative discrete element strategy has been implemented in two user-oriented software codes 3DMacro (Caliò et al., 2012b) and HiStrA (Historical Structures Analysis) (Caliò et al., 2015), which simplify the modeling of buildings and historical structures by means of several wizard generation tools and input/output facilities. The proposed approach, that represents a powerful tool for the structural assessment of structures in which the masonry plays a key role, is here validated against experimental results involving typical masonry monumental substructural elements and numerical results involving real-scale structures

A macro‐model for describing the in‐plane seismic response of masonry‐infilled frames with sliding/flexible joints

Masonry infill walls are among the most vulnerable components of reinforced concrete (RC) frame structures. Recently, some techniques for enhancing the performance of the infills have been proposed, aiming at improving both the global and the local behaviour of the infilled frame structure. Among the most promising ones, there are those that aim to decouple or reduce the infill-frame interaction by means of flexible or sliding joints, relying respectively on rubber or low-friction materials at the interface between horizontal subpanels or between the panels and the frame. Numerous models have been developed in the last decades for describing the seismic response of masonry-infilled RC frames, but these have focused mainly on the case of traditional infills. This study aims to fill this gap by proposing a two-dimensional macro-element model for describing the in-plane behaviour of RC infilled frames with flexible or sliding joints. The proposed modelling approach, implemented in OpenSees, is an extension of a discrete macro-element previously developed for the case of traditional infill panels. It is calibrated and validated in this study against quasi-static tests from the literature, carried out on masonry-infilled RC frames with sliding and rubber joints. The study results show the capabilities of the proposed modelling approach to evaluate the benefits of using flexible joints in terms of minimising the negative effects of the interaction between infill and RC frame and limiting the increase of global stiffness of the system with respect to the bare frame condition

Liraglutide Improves Cardiovascular Risk as an Add-on to Metformin and Not to Insulin Secretagogues in Type 2 Diabetic Patients: A Real-life 48-Month Retrospective Study.

INTRODUCTION: Although liraglutide is widely recognized to have glycemic and extra-glycemic effects, few studies have compared these effects in relation to hypoglycemic treatment starting from the diagnosis of diabetes. We evaluated the effectiveness of liraglutide in reducing the Framingham risk score (FRS) and visceral adiposity index (VAI) in relation to first-line hypoglycemic treatment from diagnosis of type 2 diabetes, continued without any changes. METHODS: We selected 105 diabetic outpatients who were treated with liraglutide for at least 48 months as an add-on therapy to metformin alone (group A, n = 52) or insulin secretagogues (group B, n = 53) from diagnosis time. RESULTS: Although both groups showed a reduction in BMI, waist circumference, blood pressure, HbA1c and triglycerides, only group A showed a significant reduction in FRS (p < 0.001) and VAI (p = 0.012) after 48 months. No significant intergroup difference was found for any parameters at either baseline or 48 months, with the exception of FRS at 48 months, lower in group A (p = 0.002), regardless of duration of disease, improvement in glycemic control and VAI. CONCLUSION: Our data show that during a 48-month follow-up liraglutide was more efficacious in reducing cardiovascular risk than when it was used as add-on therapy to the first-line therapy from diagnosis with metformin and not with insulin secretagogues

No phenotypic differences for polycystic ovary syndrome (PCOS) between women with and without type 1 diabetes mellitus.

CONTEXT: Women with type 1 diabetes mellitus (DM1) have a higher prevalence of polycystic ovary syndrome (PCOS) than the general population. OBJECTIVE: The aim of this study was to clarify, in DM1 women with PCOS (PCOS-DM1), the influence of insulin therapy and glycemic control and evaluate the hormonal and phenotypic differences with age-matched and body mass index (BMI)-matched women with PCOS without diabetes. DESIGN, SETTING, AND PATIENTS: We evaluated 103 DM1 women with and without PCOS treated with intensive insulin therapy; 38 age-matched and BMI-matched women with PCOS without diabetes were compared in a cross-sectional study. OUTCOME MEASUREMENTS: Clinical, anthropometric, and metabolic parameters were evaluated. Hormonal evaluation and ovary ultrasound were performed during the follicular phase of the menstrual cycle. RESULTS: Applying the diagnostic criteria of the Androgen Excess Society, 38 (36.89%) women with DM1 showed PCOS. The 38 PCOS-DM1 women showed no differences in treatment and glycemic control compared with DM1 women without PCOS. The only difference was a higher visceral adiposity index in PCOS-DM1 (1.21±0.70 vs 0.90±0.32; P=.002). PCOS-DM1 showed no phenotypic differences with age-matched and BMI-matched PCOS without diabetes. The hormonal pattern was similar except that higher levels of Δ4androstenedione were found in PCOS-DM1 (12.89±3.49 vs 2.79±1.75 nmol/L; P=.010). CONCLUSIONS: The women with PCOS-DM1 do not exhibit particular phenotypic characteristics compared with nondiabetic women with PCOS. However, this pathological disorder must not be underestimated because it could be an additional cardiovascular risk factor in women with DM1

OER nelle Università italiane: primi risultati di un'indagine conoscitiva del Gruppo CRUI OA-OER

Le OER si inseriscono nell'ambito del movimento Open Access e dell'accesso aperto alla conoscenza, ritenuta come bene comune e prevedono licenze aperte costruite nel rispetto dei diritti di proprietà intellettuale dell’autore come stabilito dalle convenzioni internazionali e dalle normative europee e nazionali. All’inizio del 2006, nell’ambito della Commissione biblioteche della CRUI, è stato costituito il Gruppo di lavoro per l’Open Access, coordinato dal prof. Roberto Delle Donne, con il compito di dare attuazione ai principi della Dichiarazione di Berlino. Il Gruppo CRUI Open Access ha creato un sottogruppo OER. Durante l'avvio della discussione del Sottogruppo OA-OER, ci si è accordati sull'idea di realizzare un'indagine e di creare una mappa dello stato dell'arte di OER in Italia. Il contributo presenta i primi risultati dell'indagine sulle OER nelle Università italiane

Durability of a recombination catalyst-based membrane-electrode assembly for electrolysis operation at high current density

Hydrogen production through polymer electrolyte membrane water electrolysis was investigated at high current density (4 A cm-2). A PtCo recombination catalyst-based membrane-electrode assembly (MEA) was assessed in terms of performance, efficiency and durability. The electrolysis cell consisted of a thin (50 µm) perfluorosulfonic acid membrane and low platinum group metals (PGM) catalyst loadings (0.6 mgMEA PGM cm-2). An unsupported PtCo catalyst was successfully integrated in the anode. A composite catalytic layer made of IrRuOx and PtCo assisted both oxygen evolution and oxidation of hydrogen permeated through the membrane. The cell voltage for the recombination catalyst-based MEA was about 30 mV lower than the bare MEA during a 3500 h durability test. The modified MEA showed low performance losses during 3500 hours operation at high current density (4 A cm-2) with low catalyst loadings. A decay rate of 9 µV/h was observed in the last 1000 hours. These results are promising for decreasing the capital costs of polymer electrolyte membrane electrolysers. Moreover, the stable voltage efficiency of about 80% vs. the high heating value (HHV) of hydrogen at 4 A cm-2, here achieved, appears very promising to decrease operating expenditures

High-Entropy Spinel Oxides Produced via Sol-Gel and Electrospinning and Their Evaluation as Anodes in Li-Ion Batteries

In the last few years, high-entropy oxides (HEOs), a new class of single-phase solid solution materials, have attracted growing interest in both academic research and industry for their great potential in a broad range of applications. This work investigates the possibility of producing pure single-phase HEOs with spinel structure (HESOs) under milder conditions (shorter heat treatments at lower temperatures) than standard solid-state techniques, thus reducing the environmental impact. For this purpose, a large set of HESOs was prepared via sol-gel and electrospinning (by using two different polymers). Ten different equimolar combinations of five metals were considered, and the influence of the synthesis method and conditions on the microstructure, morphology and crystalline phase purity of the produced HESOs was investigated by a combination of characterization techniques. On the other hand, the presence of specific metals, such as copper, lead to the formation of minority secondary phase(s). Finally, two representative pure single-phase HESOs were preliminarily evaluated as active anode materials in lithium-ion batteries and possible strategies to enhance their rate capability and cyclability were proposed and successfully implemented. The approaches introduced here can be extensively applied for the optimization of HEO properties targeting different applications.Italian Ministry of University and Research (MUR)Peer Reviewe

Diabetic foot ulcers: Retrospective comparative analysis from Sicily between two eras

Aim: The aim of this study was to analyze changes in the incidence, management and mortality of DFU in Sicilian Type 2 diabetic patients hospitalized between two eras, i.e. 2008-2013 and 2014-2019. Methods: We compared the two eras, era1: 2008-13, era2: 2014-19. In era 1, n = 149, and in era 2, n = 181 patients were retrospectively enrolled. Results: In the population hospitalized for DFU in 2008-2013, 59.1% of males and 40.9% of females died, whilst in 2014-2019 65.9% of males and 34.1% of females died. Moderate chronic kidney disease (CKD) was significantly higher in patients that had died than in ones that were alive (33% vs. 43%, p < 0.001), just as CKD was severe (14.5% vs. 4%, p < 0.001). Considering all together the risk factors associated with mortality, at Cox regression multivariate analysis only moderate-severe CKD (OR 1.61, 95% CI 1.07-2.42, p 0.021), age of onset greater than 69 years (OR 2.01, 95% CI 1.37-2.95, p <0.001) and eGFR less than 92 ml/min (OR 2.84, 95% CI 1.51-5.34, p 0.001) were independently associated with risk of death. Conclusions: Patients with DFU have high mortality and reduced life expectancy. Age at onset of diabetic foot ulcer, eGFR values and CKD are the principal risk factors for mortality

Comparative life cycle assessment of Fe2O3-based fibers as anode materials for sodium-ion batteries

AbstractSodium-ion batteries (SIBs) potentially represent a more sustainable, less expensive and environmentally friendly alternative to lithium-ion batteries. The development of new low-cost, non-toxic, highly performing electrode materials is the key point for the SIB technology advances. This study develops a basic life cycle assessment (LCA) model for the evaluation of the production by electrospinning of iron (III) oxide-based fibers to be used as anode materials in SIBs. Indeed, it has been recently demonstrated that electrospun silicon-doped iron (III) oxide (Fe2O3) fibers exhibit outstanding electrochemical properties and gravimetric capacities never achieved before for pure Fe2O3-based anodes. The LCA methodology is utilized in order to analyze the environmental burdens (from raw material extraction to manufacturing process) of these electrode materials. The simplified comparative LCA studies, conducted to assess the environmental impacts associated with the electrospun Fe2O3 and Fe2O3:Si fibers at the same cell performance, demonstrate that the Si-doped anode material, which exhibits better electrochemical performance with respect to the undoped one, has also lower impact for each category of damage, namely human health, ecosystem quality and resources