Investigation of electrochemically-induced repassivation of Al 7075-T6 and Al 2024-T3 as a function of applied stress and galvanic corrosion

The repassivation behavior of Al alloys 7075-T6 and 2024-T3 was investigated by means of pitting scan (PS) technique (Fig. 1) (Trueba, Trasatti, 2015). The effect of mechanical load and galvanic coupling was estimated by considering principally the electrochemical characteristics of the reverse curve, namely the pit transition potential (Eptp), the associated current density (iptp) and the steepness. The load levels explored were mostly below the elastic limit, using four point bent-beam (4PBB) stress-corrosion test specimens (ASTM G39-99). CRES 304 or Ti6Al4V alloy were physically joined with Al sheet for simulating stress-induced galvanic corrosion. Different experimental variables (e.g. irev, [Cl-], pH, scan rate, etc.) were also considered. The study was complemented with corrosion morphology analysis. Please click Additional Files below to see the full abstract

Time course of risk factors associated with mortality of 1260 critically ill patients with COVID-19 admitted to 24 Italian intensive care units

Purpose: To evaluate the daily values and trends over time of relevant clinical, ventilatory and laboratory parameters during the intensive care unit (ICU) stay and their association with outcome in critically ill patients with coronavirus disease 19 (COVID-19). Methods: In this retrospective–prospective multicentric study, we enrolled COVID-19 patients admitted to Italian ICUs from February 22 to May 31, 2020. Clinical data were daily recorded. The time course of 18 clinical parameters was evaluated by a polynomial maximum likelihood multilevel linear regression model, while a full joint modeling was fit to study the association with ICU outcome. Results: 1260 consecutive critically ill patients with COVID-19 admitted in 24 ICUs were enrolled. 78% were male with a median age of 63 [55–69] years. At ICU admission, the median ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) was 122 [89–175] mmHg. 79% of patients underwent invasive mechanical ventilation. The overall mortality was 34%. Both the daily values and trends of respiratory system compliance, PaO2/FiO2, driving pressure, arterial carbon dioxide partial pressure, creatinine, C-reactive protein, ferritin, neutrophil, neutrophil–lymphocyte ratio, and platelets were associated with survival, while for lactate, pH, bilirubin, lymphocyte, and urea only the daily values were associated with survival. The trends of PaO2/FiO2, respiratory system compliance, driving pressure, creatinine, ferritin, and C-reactive protein showed a higher association with survival compared to the daily values. Conclusion: Daily values or trends over time of parameters associated with acute organ dysfunction, acid–base derangement, coagulation impairment, or systemic inflammation were associated with patient survival

A Systematic Review and International Web-Based Survey of Randomized Controlled Trials in the Perioperative and Critical Care Setting: Interventions Reducing Mortality

The authors aimed to identify interventions documented by randomized controlled trials (RCTs) that reduce mortality in adult critically ill and perioperative patients, followed by a survey of clinicians’ opinions and routine practices to understand the clinicians’ response to such evidence. The authors performed a comprehensive literature review to identify all topics reported to reduce mortality in perioperative and critical care settings according to at least 2 RCTs or to a multicenter RCT or to a single-center RCT plus guidelines. The authors generated position statements that were voted on online by physicians worldwide for agreement, use, and willingness to include in international guidelines. From 262 RCT manuscripts reporting mortality differences in the perioperative and critically ill settings, the authors selected 27 drugs, techniques, and strategies (66 RCTs, most frequently published by the New England Journal of Medicine [13 papers], Lancet [7], and Journal of the American Medical Association [5]) with an agreement ≥67% from over 250 physicians (46 countries). Noninvasive ventilation was the intervention supported by the largest number of RCTs (n = 13). The concordance between agreement and use (a positive answer both to “do you agree” and “do you use”) showed differences between Western and other countries and between anesthesiologists and intensive care unit physicians. The authors identified 27 clinical interventions with randomized evidence of survival benefit and strong clinician support in support of their potential life-saving properties in perioperative and critically ill patients with noninvasive ventilation having the highest level of support. However, clinician views appear affected by specialty and geographical location

A gold nanoparticle chemically modified gold electrode for the determination of surfactants

A chemically modified electrode (CME) bearing gold nanoparticles assembled onto a gold electrode via a 1,4-benzenedimethanethiol SAM bridge has been successfully employed for the determination of surfactants in solution, using a redox probe and exploiting the tendency of surfactants to be adhere to the high-energy nanoparticles' surfac

Correlation among mandibular, femoral, lumbar and cervical bone density

INTRODUÇÃO: diante da maior frequência de pacientes adultos que se submetem atualmente ao tratamento ortodôntico, as condições gerais de saúde dessa faixa etária têm sido motivo de investigações correlacionadas aos eventos ligados ao metabolismo ósseo, haja vista que os movimentos dentários são dependentes do processo de remodelação óssea, ainda que num nível local. Diferentes padrões de densidade óssea podem acarretar diferentes respostas ao movimento ortodôntico. OBJETIVOS: o presente estudo avaliou a correlação da densidade mineral óssea (DMO) geral com aquela da região mandibular. MÉTODOS: para tanto, 22 mulheres saudáveis, com idades entre 30 e 45 anos, foram selecionadas para os exames de densitometria óssea das regiões lombar, cervical e femural, bem como da região mandibular. Foram testadas as correlações entre essas leituras e, também, estabelecidos valores de referência para as áreas cervical e mandibular. RESULTADOS: os resultados não demonstraram correlação significativa entre a densidade mandibular e as demais áreas estudadas. Houve correlação significativa apenas entre a região cervical e a femural. O valor médio DMO normal para a região mandibular foi de 0,983g/cm² (d.p. = 0,334), enquanto para a região cervical foi de 0,768g/cm² (d.p. = 0,102), e os valores médios para a região lombar e femural foram de, respectivamente, 1,127g/cm² (d.p. = 0,067) e 0,925g/cm² (d.p. = 0,078), esses últimos semelhantes aos valores de referência da Organização Mundial de Saúde. CONCLUSÕES: sugere-se que o exame da área femural possa abranger o valor esperado para a área cervical, entretanto há necessidade do exame densitométrico particular para a área mandibular, não sendo adequada a extrapolação dos valores tradicionais (lombar e femural) para estimativa dessa área. Estudos adicionais são necessários para avaliar as variações densitométricas locais e eventual influência sobre a movimentação ortodôntica.INTRODUCTION: Due to the rise in frequency of adult patients who currently are submitted to orthodontic treatment, general health conditions of this age have been a reason of inquiries correlated to events related to bone metabolism, as dental movements are dependent on the process of bone remodeling, even though in a local level. Different standards of bone density can give different answers to the orthodontic movement. AIM: The present study evaluated the correlation of the general bone mineral density (BMD) to the mandibular region. METHODS: Therefore, 22 healthy women aged between 30 and 45 years old were selected for bone densitometry examinations of lumbar, cervical, femoral, as well as mandibular alveolar region. The correlations to these readings were tested as well as values of reference were established for cervical and mandibular areas. RESULTS: The results did not demonstrate significant correlation among the mandibular density to the others studied areas. There was only significant correlation between cervical and femural region. Normal BMD average value for mandibular region was 0.983g/cm² (SD = 0.334), whereas for cervical region was 0.768g/cm² (SD = 0.102), and the average values for lumbar and femoral regions were respectively 1.127g/cm² (SD = 0.067) and 0.925g/cm² (SD = 0.078), these last ones were similar to the reference values of World Health Organization (WHO). CONCLUSIONS: It is suggested that the examination of the femoral area can comprehend the expected value to cervical area, however particular densitometry examination for the mandibular area is needed, and the exploration of the traditional values (lumbar and femoral) is not appropriate to the estimative of this area. Additional studies are necessary to evaluate local density variations and its influence on orthodontic movement

Evaluation of anti-inflammatory treatments for CF lung disease in murine models of lung infection in vivo

Glycosidase inhibition is expected to be addressed toward specific non-enantioselective, lipophilic enzymes, such as glucocerebrosidases GBA1 and GBA2. In order to assess the effect of chirality and lipophilicity of alkylated iminosugars on the activity/selectivity of such enzymes, some D and L-alkylated iminosugars as 1 and ent-1, in particular those having a gluco-configured pseudo-saccharide moiety (DNJ derivatives) have been synthesize

Effect of mechanical deformation on corrosion and repassivation of 2024-T3 and 7075-T6 aluminum alloys

Con il presente lavoro si riporta l’effetto dell’applicazione di una condizione di sollecitazione a flessione sui meccanismi di corrosione e ripassivazione delle leghe di alluminio 2024-T3 e 7075-T6 in soluzioni aggressive di NaCl, investigati tramite polarizzazione anodica a singolo ciclo ed esperimenti di corrosione galvanica. Sono stati applicati carichi fino al raggiungimento della tensione di snervamento di ogni specifica lega utilizzando provini di tensocorrosione in condizione di sollecitazione a flessione su 4 punti (4PBB). L’effetto del carico a flessione (a sollecitazione costante) sul comportamento elettrochimico risulta più evidente per la lega Al 7075-T6, anche in presenza di accoppiamento galvanico con CRES 304. Una condizione elettrochimica critica, associata all’insorgenza di microplasticità, è stata identificata dal comportamento a ripassivazione. L’esistenza di tale punto critico, sebbene meno evidente, può essere indicata anche per la lega Al 2024-T3. In questo caso, l’effetto della sollecitazione meccanica è probabilmente mascherato dalla corrosione microstrutturale tipica della lega in questione (microstructural pitting), derivante dalla presenza nella stessa di intermetallici a funzione catodica ricchi in rame. I risultati complessivi sottolineano l'interdipendenza nella tensocorrosione delle leghe di Al tra ambiente aggressivo, evento elettrochimico e stato meccanico.The present work reports on the effect of constant bending load on corrosion and repassivation of high strength 2024-T3 and 7075-T6 Al alloys in NaCl solutions, investigated by means of single cycle anodic polarization and galvanic corrosion experiments. Bending loads up to the yield strength of a given alloy were applied using four point bent beam stress corrosion test specimens. The effect of bending load (side in tension) on the electrochemical behavior is more evident for Al 7075-T6, also in the presence of galvanic coupling with CRES 304. A critical electrochemical condition associated to the onset of microplasticity is identified from the repassivation behavior. The existence of such critical condition though less noticeable is indicated for Al 2024-T3 also. In this case, the effect of stress is likely overwhelmed by microstructural corrosion. Overall results emphasize the interdependence between the local aggressive environment, the electrochemical event and the mechanical state in the stress corrosion cracking of Al alloys