SIF Determination with Thermoelastic Stress Analysis

AbstractThis work is focused on the experimental determination of the stress intensity factor (SIF) using thermoelastic stress analysis (TSA) for a compact tension specimen during a fatigue crack growth test. A comparison of the stress field obtained with computational modelling, finite element method, against the experimental data obtained with the thermoelastic stress analysis under mode I loading in a fatigue test is presented. The stress field in front of the crack tip obtained with TSA, was used in William’s expansion, together with an overdetermined algorithm to calculate the SIF under mode I loading. The proposed methodology has a hybrid experimental-numerical nature where the stress intensity factor determination depends on a stress field obtained with an optical technique, TSA. The soundness of the experimentally obtained SIF solution was validated through finite element method computations

The Association between Myocardial Perfusion Scan and Electrocardiographic Findings among Patients with Myocardial Ischemia

Introduction: The aim of this study was to determine the consistency of Electrocardiography (ECG) and myocardial perfusion scan findings of patients with myocardial ischemia at Firoozgar and Hazrat-Rasool hospitals.Methods: Electrocardiogram of 80 patients undergoing myocardial perfusion scans was analyzed. All patients had a stable angina. All patients with bundle branch blocks and history of MI and coronary bypass or angiography were excluded. Overall, 120 patients were evaluated with single photon emission tomography/myocardial perfusion imaging for ischemia and 80 patients had a positive test.Results: Forty-five percent of patients were female and 55% were male. The average age of patients was 61.48 years. Sixty-one patients (76.25%) had normal ECG and 19 patients (23.75) had pathological changes in their ECG. Eleven patients had ST segment depression and 6 patients had T wave inversion. Furthermore, 21 patients (26.25%) had lateral wall ischemia in their myocardial perfusion scan and 13 (16.25%) patients had septal wall ischemia. The ECG changes in male patients and hypertensive cases were more prominent.Conclusions: This study showed that ST-T changes (ST depression and T inversion) in the ECG are more suggestive of accuracy of myocardial ischemia and ECG

Pulmonary Hypertension and Its Determinants in β-thalassemia Major and Intermedia Considering Left Ventricular Functional State

Introduction: Pulmonary hypertension (PHT) is a common complication in β-thalassemia. We aimed to determine the prevalence of PHT and its main indicators in patients with β thalassemia Major (TM) and β-thalassemia Intermedia (TI), considering left ventricular function.Methods: Pulmonary hypertension (PHT) is a common complication in β-thalassemia. We aimed to determine the prevalence of PHT and its main indicators in patients with β thalassemia Major (TM) and β-thalassemia Intermedia (TI), considering left ventricular function.Results: The overall prevalence of PHT in TM and TI group was estimated to be 35.2% and 29.3%, respectively; while reduced LVEF was evident in 22.7% and 10.1% of patients with TM and TI, respectively. No significant correlation was observed between mean PAP and LVEF in the patients with TI (Pearson coefficient = -0.096, P value = 0.345); while, an adverse association was revealed between mean PAP and LVEF in patients with TM (Pearson coefficient = -0.227, P value = 0.033). Upon univariate analysis, the only significant association was observed between LVEF and pulmonary hypertension among TM patients (P value = 0.001).Our results did not indicate that male gender and aging may affect the development of PHT.Conclusions: According to our findings, a considerable proportion of patients with TM and TI may have PHT. We detected an adverse association between mean PAP and LVEF in patients with TM. Left ventricular function was reduced in patients with PHT among TM group

Differential Co-Expression Network Analysis Reveals Key Hub-High Traffic Genes as Potential Therapeutic Targets for COVID-19 Pandemic

BackgroundThe recent emergence of COVID-19, rapid worldwide spread, and incomplete knowledge of molecular mechanisms underlying SARS-CoV-2 infection have limited development of therapeutic strategies. Our objective was to systematically investigate molecular regulatory mechanisms of COVID-19, using a combination of high throughput RNA-sequencing-based transcriptomics and systems biology approaches. MethodsRNA-Seq data from peripheral blood mononuclear cells (PSPRINGER NATUREs) of healthy persons, mild and severe 17 COVID-19 patients were analyzed to generate a gene expression matrix. Weighted gene co-expression network analysis (WGCNA) was used to identify co-expression modules in healthy samples as a reference set. For differential co-expression network analysis, module preservation and module-trait relationships approaches were used to identify key modules. Then, protein-protein interaction (PPI) networks, based on co-expressed hub genes, were constructed to identify hub genes/TFs with the highest information transfer (hub-high traffic genes) within candidate modules. ResultsBased on differential co-expression network analysis, connectivity patterns and network density, 72% (15 of 21) of modules identified in healthy samples were altered by SARS-CoV-2 infection. Therefore, SARS-CoV-2 caused systemic perturbations in host biological gene networks. In functional enrichment analysis, among 15 non-preserved modules and two significant highly-correlated modules (identified by MTRs), 9 modules were directly related to the host immune response and COVID-19 immunopathogenesis. Intriguingly, systemic investigation of SARS-CoV-2 infection identified signaling pathways and key genes/proteins associated with COVID-19's main hallmarks, e.g., cytokine storm, respiratory distress syndrome (ARDS), acute lung injury (ALI), lymphopenia, coagulation disorders, thrombosis, and pregnancy complications, as well as comorbidities associated with COVID-19, e.g., asthma, diabetic complications, cardiovascular diseases (CVDs), liver disorders and acute kidney injury (AKI). Topological analysis with betweenness centrality (BC) identified 290 hub-high traffic genes, central in both co-expression and PPI networks. We also identified several transcriptional regulatory factors, including NFKB1, HIF1A, AHR, and TP53, with important immunoregulatory roles in SARS-CoV-2 infection. Moreover, several hub-high traffic genes, including IL6, IL1B, IL10, TNF, SOCS1, SOCS3, ICAM1, PTEN, RHOA, GDI2, SUMO1, CASP1, IRAK3, HSPA5, ADRB2, PRF1, GZMB, OASL, CCL5, HSP90AA1, HSPD1, IFNG, MAPK1, RAB5A, and TNFRSF1A had the highest rates of information transfer in 9 candidate modules and central roles in COVID-19 immunopathogenesis. ConclusionThis study provides comprehensive information on molecular mechanisms of SARS-CoV-2-host interactions and identifies several hub-high traffic genes as promising therapeutic targets for the COVID-19 pandemic

Biomechanical effects of Teuscher activator in hyperdivergent Class II malocclusion treatment : a finite element analysis

In orthodontic treatment, the combination of an activator with a headgear is commonly used in treatment of the hyperdivergent Class II malocclusion. However, the distribution of stresses transmitted to the maxilla by these appliances has been little stud

Non-alcoholic fatty liver disease is not independent risk factor for cardiovascular disease event : a cohort study

There are no consistent results between previous studies for an independent association between non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD) events. To determine if there is an independent association between NAFLD and CVD events. In the present study, valid outcome data of 4808 subjects were available for phase 2 of our cohort study. These subjects had been followed up for seven years from phase 1, beginning in 2009-2010 to phase 2 during 2016-2017. Simple and multiple Cox proportional models were used to determine the association between NAFLD in the primary phase of the cohort and subsequent fatal and non-fatal CVD events during follow-up. The incidence of non-fatal CVD events in males with NAFLD was significantly higher ( = 0.004) than in males without NAFLD. A positive association was demonstrated between NAFLD and non-fatal CVD events in males (Hazard ratio = 1.606; 95%CI: 1.166-2.212; = 0.004) by the simple Cox proportional hazard model, but no independent association was detected between these in the multiple Cox models. No independent association was detected between NAFLD and CVD. It is likely that diabetes mellitus and age may be the principle mediators in this regard. [Abstract copyright: ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.

The prevalence of left ventricular heart failure in chronic obstructive pulmonary disease patients: brief report

Background: Chronic obstructive pulmonary disease (COPD) and heart failure are prevalent comorbidities affecting a vast proportion of the world population, responsible for significant morbidity and mortality, their coexistence is more frequent than previously recognized that poses important diagnostic and therapeutic challenges. We intend to determine the prevalence of concomitant left ventricular dysfunction in COPD patients. Methods: We performed a cross-sectional study in patients who had referred to Firuzgar University Hospital in Tehran from March 2011 to March 2013 in period of 2 years. All participants were compatible for including and excluding criteria’s. In all cases of COPD, pulmonary function test was done; also Echocardiography was performed as the diagnostic assessment of heart failure. Results: Out of 74 participants there was 56(75.7%) male and 18(24.3%) female with the mean age of 67.712.9 (SD), the prevalence of left ventricular systolic dysfunction (LVSD) was 25.70%, also the prevalence of left ventricular diastolic dysfunction (LVDD) was 74.60% among 71 patients. The prevalence of LVSD in patients with and without history of coronary artery disease (CAD) was 33.30% and 15.60% respectively. The prevalence of LVDD was 85.40% in patient with history of CAD and 60% in patients without it. The presence of ventricular dysfunction (neither systolic nor diastolic) in COPD patients was not statistically associated with presence of CAD or the intensity of underlying COPD disease. Conclusion: Knowledge about the prevalence of concomitant left side heart failure in COPD patients is limited, but it seems the presence is rather common, so more attention should be paid to coexistence of ventricular dysfunction in COPD patients disregarding presence of CAD or COPD intensity in clinical practice

Fracture toughness determination on an SCB specimen by meshless methods

This work investigates fracture characteristics of a marble semi-circular bend (SCB) specimen with a pre-defined crack under a compressive loading condition. It aims at evaluating how the fracture toughness can be affected by the crack and span length variation. Numerically, the model is solved using meshless methods, extended to the linear elastic fracture mechanics (LEFM), resorting to radial point interpolation method (RPIM) and its natural neighbor versions (NNRPIMv1 and NNRPIMv2). Alternatively, to validate the meshless method results, the problem is resolved following the finite element method (FEM) model based on the standard 2D constant strain triangle elements. As a result, fracture toughness and the critical strain energy release rate are characterized following the testing method on the cracked straight through semi-circular bend specimen (CSTSCB). A comparison is drawn amongst the theoretical, meshless methods and FEM results to evaluate the capability of advanced numerical methods. Encouraging results have been accomplished leading to validate the supporting numerical methodologies.Behzad V. Farahani gratefully acknowledges the funding received from Ministério da Educação e Ciência, Fundação para a Ciência e a Tecnologia (Portugal), under grant PTDC/EME-EME/29339/2017. Farid Mehri Sofiani expresses his deep gratitude to Professor Paulo Tavares de Castro (https://sigarra.up.pt/feup/en/FUNC_GERAL.FORMVIEW?p_codigo=207900 (accessed on 20 December 2021)) for advice and assistance in a course project in which present work initially developed and afterwards extended.info:eu-repo/semantics/publishedVersio