Influenza del comportamento ciclico dei collegamenti trave-colonna sulla risposta sismica di telai in acciaio regolari o in presenza di "set-backs"

2012 - 2013In accordo con i criteri della progettazione sismica tradizionale, la dissipazione dell’energia sismica in ingresso nei telai sismo-resistenti avviene in alcune zone degli elementi strutturali che vengono impegnate in campo plastico e che, quindi, devono essere dettagliate in maniera appropriata al fine di assicurare cicli di isteresi ampi e stabili. Le zone dissipative possono essere localizzate alle estremità della trave o negli elementi di collegamento a seconda della tipologia di nodo trave-colonna impiegata. Infatti, le connessioni trave-colonna possono essere progettate sia come nodi a completo ripristino di resistenza, con una sufficiente sovraresistenza rispetto alla trave collegata concentrando le zone dissipative alle estremità delle travi, o come nodo a parziale ripristino di resistenza, di modo che l’energia sismica in ingresso è dissipata attraverso l’impegno plastico di componenti nodali opportunamente selezionate. Il presente lavoro si propone di valutare l’influenza della tipologia di nodi trave colonna a parziale ripristino di resistenza sulla risposta sismica di telai sismo-resistenti in acciaio regolari e con irregolarità di tipo “set-backs”, a partire dalla conoscenza del comportamento rotazionale ciclico dei collegamenti, al fine di sviluppare metodologie più accurate per la valutazione della prestazione sismica di strutture con tale tipo di connessioni. Le strutture utilizzate sono telai sismo-resistenti in acciaio piani progettati adottando una rigorosa metodologia basata sui teoremi limite del collasso plastico in grado di assicurare lo sviluppo di un meccanismo di collasso di tipo globale. Le tipologie di connessione considerate sono quattro nodi a parziale ripristino di resistenza, progettati al fine di ottenere la stessa resistenza flessionale di progetto partendo da dettagli costruttivi differenti e quindi portando a risorse di duttilità e caratteristiche dissipative del tutto diverse. Le prime tre connessioni sono state progettate mediante criteri di gerarchia a livello delle singole componenti mentre la quarta connessione è un nodo trave-colonna equipaggiato con dissipatori ad attrito posizionati in corrispondenza delle flange della trave collegata progettato e dettagliato al fine di dissipare l’energia sismica in ingresso in funzione del massimo spostamento richiesto in occasione di eventi sismici di tipo distruttivo. L’utilizzo di questi nodi trave colonna è legato alla disponibilità di risultati sperimentali relativi alla loro risposta rotazionale ciclica, in quanto essi sono stati testati all’interno di sub-assemblaggi strutturali presso il laboratorio delle strutture dell’Università degli Studi di Salerno. Infatti, il comportamento ciclico di tali nodi trave-colonna è complicato dallo sviluppo di degrado di resistenza e rigidezza e dal fenomeno del pinching all’aumentare del numero di cicli, fenomeni governati da regole che non possono essere dedotte mediante approcci teorici semplificati. Al fine di valutare la risposta sismica dei telai in acciaio sismo-resistenti, è necessaria una modellazione accurata della struttura che sia in grado di rappresentarne correttamente sia la rigidezza che le caratteristiche di deformabilità, specialmente con riferimento alle connessioni trave-colonna, essendo la dissipazione dell’energia sismica in ingresso ottenuta attraverso la plasticizzazione di tali elementi. Nello specifico, i nodi trave-colonna sono stati modellati attraverso elementi molla rotazionale inelastica posizionati alle estremità delle travi la cui curva momento-rotazione è caratterizzata da un comportamento ciclico che porta in conto sia il degrado di resistenza che di rigidezza, nonché, il fenomeno del pinching. Successivamente, è stata portata avanti una ricerca volta ad ottenere, a partire dal comportamento ciclico dei nodi così modellati, una previsione della risposta sismica della struttura attraverso l’uso di analisi dinamiche al fine di investigare l’influenza del dettaglio costruttivo del nodo sulla risposta sismica dei telai sismo-resistenti in acciaio regolari. [a cura dell'autore]XII n.s

Bioengineering, augmented reality, and robotic surgery in vascular surgery: A literature review

Biomedical engineering integrates a variety of applied sciences with life sciences to improve human health and reduce the invasiveness of surgical procedures. Technological advances, achieved through biomedical engineering, have contributed to significant improvements in the field of vascular and endovascular surgery. This paper aims to review the most cutting-edge technologies of the last decade involving the use of augmented reality devices and robotic systems in vascular surgery, highlighting benefits and limitations. Accordingly, two distinct literature surveys were conducted through the PubMed database: the first review provides a comprehensive assessment of augmented reality technologies, including the different techniques available for the visualization of virtual content (11 papers revised); the second review collects studies with bioengineering content that highlight the research trend in robotic vascular surgery, excluding works focused only on the clinical use of commercially available robotic systems (15 papers revised). Technological flow is constant and further advances in imaging techniques and hardware components will inevitably bring new tools for a clinical translation of innovative therapeutic strategies in vascular surgery

Molecular modeling studies, synthesis, configurational stability and biological activity of 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide

The potential therapeutic benefit of compounds able to activate AMPA receptors (AMPArs) has led to a search for new AMPAr positive modulators. Among them, 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide (1) has attracted particular attention, because it is one of the most active benzothiadiazine\u2013derived positive modulators of the AMPA receptor. It possesses two stereogenic centers, C3 and C6, thus it can exist as four stereoisomers. In this work, preliminary in silico studies suggested that 1 interacts stereoselectively with AMPArs. Single stereoisomers of 1 were prepared in order to evaluate their biological activity. However, studies regarding the configurational stability of the investigated compounds suggested a rapid epimerization at C3 in aqueous solvents, and we can expect the same reaction in vivo. Thus, electrophysiological experiments were performed on the two epimeric mixtures, (3 17,6R)- and (3 17,6S)- 8-chloro-2,3,5,6-tetrahydro-3,6-dimethyl-pyrrolo[1,2,3-de]-1,2,4-benzothiadiazine 1,1-dioxide, in order to evaluate their activities as positive allosteric modulators of AMPArs. The obtained data suggest that the (3 17,6S) epimeric mixture is the most active in positively modulating AMPArs, confirming in silico results

Design, stereoselective synthesis, configurational stability and biological activity of 7-chloro-9-(furan-3-yl)-2,3,3a,4-tetrahydro-1H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine 5,5-dioxide

Chiral 5-arylbenzothiadiazine derivatives have recently attracted particular attention because they exhibit an interesting pharmacological activity as AMPA receptor (AMPAr) positive modulators. However, investigations on their configurational stability suggest a rapid enantiomerization in physiological conditions. In order to enhance configurational stability, preserving AMPAr activity, we have designed the novel compound (R,S)-7-chloro-9-(furan-3-yl)-2,3,3a,4-tetrahydro-1H-benzo[e]pyrrolo[2,1-c][1,2,4]thiadiazine 5,5-dioxide bearing a pyrrolo moiety coupled with the 5-(furan-3-yl) substituent on benzothiadiazine core. A stereoselective synthesis was projected to obtain single enantiomer of the latter compound. Absolute configuration was assigned by X-ray crystal structure. Patch clamp experiments evaluating the activity of single enantiomers as AMPAr positive allosteric modulator showed that R stereoisomer is the active component. Molecular modeling studies were performed to explain biological results. An on-column stopped-flow bidimensional recycling HPLC procedure was applied to obtain on a large scale the active enantiomer with enantiomeric enrichment starting from the racemic mixture of the compound

Aquaporin-9 Contributes to the Maturation Process and Inflammatory Cytokine Secretion of Murine Dendritic Cells

Dendritic cells (DCs) are the most potent antigen-presenting cells able to trigger the adaptive immune response to specific antigens. When non-self-antigens are captured, DCs switch from an “immature” to a “mature” state to fulfill their function. Among the several surface proteins involved in DCs maturation, the role of aquaporins (AQPs) is still poorly understood. Here we investigated the expression profile of Aqps in murine bone marrow derived dendritic cells (BMDCs). Among the Aqps analyzed, Aqp9 was the most expressed by DCs. Its expression level was significantly upregulated 6 h following LPS exposure. Chemical inhibition of Aqp9 led to a decreased inflammatory cytokines secretion. BMDCs from AQP9-KO mice release lower amount of inflammatory cytokines and chemokines and increased release of IL-10. Despite the reduced release of inflammatory cytokines, Aqp9-KO mice were not protected from DSS induced colitis. All together, our data indicate that AQP9 blockade can be an efficient strategy to reduce DCs inflammatory response but it is not sufficient to protect from acute inflammatory insults such as DSS induced colitis

Genome-wide Association Study Identifies Two Susceptibility Loci for Osteosarcoma

Osteosarcoma is the most common primary bone malignancy of adolescents and young adults. In order to better understand the genetic etiology of osteosarcoma, we performed a multi-stage genome-wide association study (GWAS) consisting of 941 cases and 3,291 cancer-free adult controls of European ancestry. Two loci achieved genome-wide significance: rs1906953 at 6p21.3, in the glutamate receptor metabotropic 4 [GRM4] gene (P = 8.1 ×10-9), and rs7591996 and rs10208273 in a gene desert on 2p25.2 (P = 1.0 ×10-8 and 2.9 ×10-7). These two susceptibility loci warrant further exploration to uncover the biological mechanisms underlying susceptibility to osteosarcoma

Roadmap on Photovoltaic Absorber Materials for Sustainable Energy Conversion

Photovoltaics (PVs) are a critical technology for curbing growing levels of anthropogenic greenhouse gas emissions, and meeting increases in future demand for low-carbon electricity. In order to fulfil ambitions for net-zero carbon dioxide equivalent (CO2eq) emissions worldwide, the global cumulative capacity of solar PVs must increase by an order of magnitude from 0.9 TWp in 2021 to 8.5 TWp by 2050 according to the International Renewable Energy Agency, which is considered to be a highly conservative estimate. In 2020, the Henry Royce Institute brought together the UK PV community to discuss the critical technological and infrastructure challenges that need to be overcome to address the vast challenges in accelerating PV deployment. Herein, we examine the key developments in the global community, especially the progress made in the field since this earlier roadmap, bringing together experts primarily from the UK across the breadth of the photovoltaics community. The focus is both on the challenges in improving the efficiency, stability and levelized cost of electricity of current technologies for utility-scale PVs, as well as the fundamental questions in novel technologies that can have a significant impact on emerging markets, such as indoor PVs, space PVs, and agrivoltaics. We discuss challenges in advanced metrology and computational tools, as well as the growing synergies between PVs and solar fuels, and offer a perspective on the environmental sustainability of the PV industry. Through this roadmap, we emphasize promising pathways forward in both the short- and long-term, and for communities working on technologies across a range of maturity levels to learn from each other.Comment: 160 pages, 21 figure

Obstetric history and mammographic density: a population-based cross-sectional study in Spain (DDM-Spain)

High mammographic density (MD) is used as a phenotype risk marker for developing breast cancer. During pregnancy and lactation the breast attains full development, with a cellular-proliferation followed by a lobular-differentiation stage. This study investigates the influence of obstetric factors on MD among pre- and post-menopausal women. We enrolled 3,574 women aged 45–68 years who were participating in breast cancer screening programmes in seven screening centers. To measure MD, blind anonymous readings were taken by an experienced radiologist, using craniocaudal mammography and Boyd’s semiquantitative scale. Demographic and reproductive data were directly surveyed by purpose-trained staff at the date of screening. The association between MD and obstetric variables was quantified by ordinal logistic regression, with screening centre introduced as a random effect term. We adjusted for age, number of children and body mass index, and stratified by menopausal status. Parity was inversely associated with density, the probability of having high MD decreased by 16% for each new birth (P value < 0.001). Among parous women, a positive association was detected with duration of lactation [>9 months: odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.02–1.72] and weight of first child (>3,500 g: OR = 1.32; 95% CI = 1.12–1.54). Age at first birth showed a different effect in pre- and post-menopausal women (P value for interaction = 0.030). No association was found among pre-menopausal women. However, in post-menopausal women the probability of having high MD increased in women who had their first child after the age of 30 (OR = 1.53; 95% CI = 1.17–2.00). A higher risk associated with birth of twins was also mainly observed in post-menopausal women (OR = 2.02; 95% CI = 1.18–3.46). Our study shows a greater prevalence of high MD in mothers of advanced age at first birth, those who had twins, those who have breastfed for longer periods, and mothers whose first child had an elevated birth weight. These results suggest the influence of hormones and growth factors over the proliferative activity of the mammary gland