Mechanical Behavior of Lithium-Ion Battery Separators under Uniaxial and Biaxial Loading Conditions.

The mechanical integrity of two commercially available lithium-ion battery separators was investigated under uniaxial and biaxial loading conditions. Two dry-processed microporous films with polypropylene (PP)/polyethylene (PE)/polypropylene (PP) compositions were studied: Celgard H2010 Trilayer and Celgard Q20S1HX Ceramic-Coated Trilayer. The uniaxial tests were carried out along the machine direction (MD), transverse direction (TD), and diagonal direction (DD). In order to generate a state of in-plane biaxial tension, a pneumatic bulge test setup was prioritized over the commonly performed punch test in an attempt to eliminate the effects of contact friction. The biaxial flow stress-strain behavior of the membranes was deduced via the Panknin-Kruglov method coupled with a 3D Digital Image Correlation (DIC) technique. The findings demonstrate a high degree of in-plane anisotropy in both membranes. The ceramic coating was found to negatively affect the mechanical performance of the trilayer microporous separator, compromising its strength and stretchability, while preserving its failure mode. Derived from experimentally calibrated constitutive models, a finite element model was developed using the explicit solver OpenRadioss. The numerical model was capable of predicting the biaxial deformation of the semicrystalline membranes up until failure, showing a fairly good correlation with the experimental observations.

Elasto-Static Analysis of Composite Restorations in a Molar Tooth: A Meshless Approach.

Dental caries and dental restorations possess a long history and over the years, many materials and methods have been invented. In recent decades, modern techniques and materials have brought complexity to this issue, which has created the necessity to investigate more and more to achieve durability, consistency, proper mechanical properties, efficiency, beauty, good colour, and reduced costs and time. Combined with the recent advances in the medical field, mechanical engineering plays a significant role in this topic. This work aims at studying the elasto-static response of a human molar tooth as a case study, respecting the integral property of the tooth and different composite materials of the dental restoration. The structural integrity of the case study will be assessed through advanced numerical modelling resorting to meshless methods within the stress analysis on the molar tooth under different loading conditions. In this regard, bruxism is considered as being one of the most important cases that cause damage and fracture in a human tooth. The obtained meshless methods results are compared to the finite element method (FEM) solution. The advantages and disadvantages of the analysed materials are identified, which could be used by the producers of the studied materials to improve their quality. On the other hand, a computational framework, as the one presented here, would assist the clinical practice and treatment decision (in accordance with each patient's characteristics).

Scoring systems of metabolic syndrome and prediction of cardiovascular events: A population based cohort study.

BACKGROUND AND AIMS: Continuous scoring systems were developed versus traditional dichotomous approaches to define metabolic syndrome. The current study was carried out to evaluate the ability of scoring systems to predict fatal and nonfatal cardiovascular events. MATERIALS AND METHODS: The data of 5147 individuals aged 18 years or more obtained from a population-based cohort study were analyzed. The occurrence of atherosclerotic cardiovascular disease (ASCVD) in the period of 7 years follow-up was considered as the associated outcome. Joint Interim Statement (JIS) definition, as a traditional definition of metabolic syndrome (MetS), and two versions of MetS scoring systems, based on standardized regression weights from structural equation modeling (SEM) and simple method for quantifying metabolic syndrome (siMS) were considered as potential predictors. RESULTS: The scoring systems, particularly, based on SEM, were observed to have a significant association with composite cardiovascular events (HR = 1.388 [95% CI = 1.153-1.670], p = .001 in men and HR = 1.307 [0.95% CI = 1.120-1.526] in women) in multiple Cox proportional hazard regression analyses, whereas the traditional definition of MetS did not show any significant association. While both two scoring systems showed acceptable predictive abilities for cardiovascular events in women (MetS score based on SEM: area of under curve [AUC] = 0.7438 [95% CI = 0.6195-0.7903] and siMS: AUC = 0.7207 [95% CI = 0.6676-0.7738]), the two systems were not acceptable for identifying risk in men. CONCLUSION: Unlike the dichotomous definition of MetS, the scoring systems showed an independent association with cardiovascular events. Scoring systems, particularly those based on SEM, may be useful for the prediction of cardiovascular events in women.

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

BACKGROUND: 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 studied. This study aimed to compare the biomechanical effects of stresses transmitted to the maxilla and teeth by a Teuscher activator (TA) for different lines of action of extraoral force, using finite element analysis. MATERIAL AND METHODS: A tridimensional finite element model of the maxilla and teeth was created based on the true geometry of a human skull. The (TA) and the face bow were designed in 3D computer-aided design and fixed in the maxilla model. To study the effects of mechanical stress transmitted to the maxilla in the treatment of hyperdivergent Class II malocclusion with (TA) combined with extraoral forces, five different finite element models were used, considering the centers of resistance of the maxilla and dentition. RESULTS: The results showed that stresses increased progressively when the force line of action moved in posteroanterior direction. Von Mises equivalent stress was lower in Model 1 (0°) than in Model 5 (60°). In Models 1 (0°) and 2 (15°), molars suffered greater distal displacement and incisors showed extrusion. In Model 3 (30°), the force line of action promoted a distal displacement of molars and incisors. In Models 4 (45°) and 5 (60°), the whole maxillary anterior sector showed counterclockwise displacement. CONCLUSIONS: Different force lines of action influence the intensity and distribution of orthodontic and orthopedic forces in the maxilla. The extraoral force's line of action used in Model 3 (30°) is the most compatible with the objectives of the hyperdivergent Class II malocclusion treatment in growing patients. Key words:Class II, Headgear, Early treatment, FEA.

Troponin is a useful marker in clinical decision making in hospitalized patients with COVID-19 infections.

BACKGROUND: COVID-19 was introduced by the World Health Organization (WHO) as a global pandemic. The disease manifestations ranges from a mild common cold to severe disease and death. It has a higher mortality rate in people with a history of comorbidities, including cardiovascular disease (CVD) and can also contribute to cardiac injury. This study was conducted to evaluate the relationship between troponin levels as a cardiac marker and adverse outcomes in this disease. METHODS: The study sample included 438 patients hospitalized with COVID-19; however, the troponin data of 6 patients were not available. The need to be admitted to the intensive care unit (ICU), and death were considered the adverse outcome in patients with COVID-19. Troponin levels were checked in all patients on day 1 and day 3 of hospitalization. Multiple logistic regression analysis was performed to determine whether there was an independent association between the adverse outcomes and troponin enzyme in hospitalized patients with COVID-19. RESULTS: The mean age of patients was 61.29 ± 15.84 years. Among the 432 patients tested on day 1 of hospitalization, 24 patients (5.6%) tested positive (Troponin 1), and among the 303 patients tested on day 3, 13 patients (4.3%) tested positive (Troponin 2). Based on our results, Troponin 1 showed an independent association with both death (3.008 [95%CI = 1.091-8.290]; P = 0.033) and need for ICU admission (8.499 [95%CI = 3.316-21.788]; P < 0.001) in multiple logistic regression analysis. Moreover, the status of Troponin 2 had an independent significant association with both death (4.159 [95%CI = 1.156-14.961]; P = 0.029) and ICU admission (7.796 [95%CI = 1.954-31.097]; P = 0.004). CONCLUSION: Troponin showed a significant association with adverse outcomes in people who were hospitalized with COVID-19. The periodical assessment of this enzyme from the time of hospitalization may improve the clinical decision making of clinicians.

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

BACKGROUND: There are no consistent results between previous studies for an independent association between non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD) events. AIM: To determine if there is an independent association between NAFLD and CVD events. METHODS: 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. RESULTS: The incidence of non-fatal CVD events in males with NAFLD was significantly higher (P = 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; P = 0.004) by the simple Cox proportional hazard model, but no independent association was detected between these in the multiple Cox models. CONCLUSION: 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.

10-year risk of cardiovascular disease and body mass index in association with the obesity paradox.

BACKGROUND: Some recent studies reported an inverse association between obesity and risk of cardiovascular diseases (CVD), heart failure related mortality rate, outcomes of myocardial infarction (MI), and the consequences of cardiovascular events interventions; this inverse association was named the obesity paradox. The present study was conducted with the aim to determine whether the obesity paradox will be detectable when the 10-year risk of CVD is estimated using CVD risk assessment tools. METHODS: The related data of 2910 subjects aged 40-74 years obtained in our cohort study that was carried out among 6140 subjects in Amol, in northern Iran, was included in this study. CVD risk assessment tools were used to estimate the 10-year risk of CVD. Obesity was evaluated using 4 indices, including waist circumference (WC), waist to height ratio (WHtR), waist to hip ratio (WHR), and body mass index (BMI). The receiver operating characteristic (ROC) curve analysis was utilized to evaluate the discriminatory power of obesity indices for 10-year risk of CVD. RESULTS: Categorizing the participants to with and without obesity according to BMI showed that a significantly higher proportion of men with obesity had a 10-year risk of CVD ≥ 7.5% and ≥ 10% according to American College of Cardiology/American Heart Association (ACC/AHA) and the Framingham approaches, respectively. A higher proportion of women without obesity had a 10-year risk of CVD ≥ 7.5% than women with obesity based on the ACC/AHA equation (28.54% vs. 24.15%; P = 0.0707). BMI had a non-significant AUC (< 0.5) according to the the ACC/AHA equation. CONCLUSION: BMI showed a weak and non-significant inverse association with 10-year risk of CVD estimated using pooled cohort equations of ACC/AHA in women. However, this result cannot directly provide enough evidence for the obesity paradox.

Echocardiographic and Electrocardiographic Findings in Patients with Ankylosing Spondylitis without Cardiovascular Risk Factors.

Background: Ankylosing spondylitis (AS) is a chronic inflammatory condition associated with more cardiac manifestations than those in the normal population. In this study, we sought to determine the prevalence of cardiac involvement in patients suffering from AS without cardiovascular risk factors. Methods: The present case-control study, conducted in 2 university hospitals in Tehran from January 2016 to December 2017, recruited 67 patients with AS and 40 age- and sex-matched healthy controls. The diagnosis of AS was based on the classification criteria of the Assessment of SpondyloArthritis International Society. All the participants were examined using transthoracic echocardiography and a standard 12-lead ECG. Baseline characteristics, echocardiographic findings, and ECG features were compared between the AS and control groups using univariate analyses. Results: The median age was 33.5 (IQR25-75%: 20.5-59) years in the AS group and 35 (IQR25-75%: 26-59) years in the control group (P=0.301). The number of patients with left ventricular systolic and diastolic dysfunction was significantly higher in the patients with AS than in the controls (7.5% vs. 20.9%; P=0.067, and 22.9% vs. 5.0%; P=0.026, respectively). The number of individuals with a left-axis deviation and a left anterior fascicular block was significantly higher in the patients suffering from AS than in the control group. The number of patients with aortic valve involvement was comparable between the groups (P=0.332). Conclusion: The most common cardiac involvement in our patients with AS was left ventricular dysfunction, followed by rhythm disturbances and aortic valve insufficiency. These findings were independent of age, AS severity, and disease duration. Therefore, the implementation of cardiovascular screening can be recommended for patients with AS.

Preventive Effect of Trimetazidine on Contrast-Induced Acute Kidney Injury in CKD Patients Based on Urinary Neutrophil Gelatinase-associated Lipocalin (uNGAL): A randomized Clinical Trial.

INTRODUCTION: Contrast-induced Acute Kidney Injury (CI-AKI) is a prevalent complication of chronic kidney disease (CKD) patients. The aim of this study was to evaluate the effects of periprocedural administration of trimetazidine as an anti-oxidant agent on the incidence of CI-AKI in CKD patients based on changes of Neutrophil Gelatinase-Associated Lipocalin (uNGAL) level, which has recently been introduced as an early predictor of CI-AKI. METHODS: One hundred CKD patients with a mean GFR of 50 ± 7 cc/min who were candidate for coronary angiography assigned randomly to receive (50 patients, intervention group) or not receive (50 patients, control group) trimetazidine (70mg/d) for 72 hours. CI-AKI was defined as 0.5 mg or 25% increase in serum creatinine. We also checked uNGAL before and 12h after angiography. RESULTS: Serum creatinine, showed a trend of less increment in the case group, although could not achieve a significant difference, there was a significant difference in urinary NGAL rise between two groups. CI-AKI was defined as 1.7 times increase in uNGAL level (12h after angiography to pre-procedurally uNGAL level ratio) according to the ROC curves. The incidence of CI-AKI according to urinary NGAL definition was 8% in the Trimetazidine group and 24% in the control group (P < .05). CONCLUSION: We concluded that Trimetazidine treatment before angiography may be effective in CI-AKI prevention. Moreover, it is shown that 1.7 times increase in urine NGAL after angiography is a valuable cut off point for clinicians to discriminate high risk patients for contrast nephropathy.

Comparison of cardiovascular risk assessment tools and their guidelines in evaluation of 10-year CVD risk and preventive recommendations: A population based study.

BACKGROUND: Identification of individuals at risk of cardiovascular diseases (CVDs) results in better clinical outcomes and may help policy makers in conscious decision making for community based and national intervention strategies. The main aim of this study was to compare various CVD risk assessment tools and their related guidelines in estimation of 10-year CVD risk and subsequent therapeutic recommendations, respectively. METHODS: Data of 3086 subjects aged 40-74years from a cohort study of northern Iran were utilized in this cross-sectional study. The risks were calculated based on American College of Cardiology/American Heart Association (ACC/AHA) tool, two versions of Systematic Coronary Risk Evaluation (SCORE) equations (for low and high risk European countries) and Framingham approach. We also detected participants who ought to be recommended for treatment based on the specific guidelines related to each of the risk assessment tools. RESULTS: Mean cardiovascular risks were 12.96%, 8.84%, 1.90% and 3.45% in men and 5.87%, 2.13%, 0.8% and 1.13% in women based on ACC/AHA, Framingham, SCORE equation for low-risk European countries and high-risk European countries, respectively. Based on ACC/AHA, Adult Treatment Panel III (ATPIII) and European Society of Cardiology (ESC) guidelines related to SCORE equations for low and high risk European countries 58.2%, 27.1%, 21.1% and 28.6% of men and 39.7%, 33.0%, 29.5% and 30.7% of women were recommended to statin therapy, respectively. CONCLUSIONS: In conclusion, more individuals were recommended for treatment by ACC/AHA guideline than the other guidelines.

Optimal cutoff points for HOMA-IR and QUICKI in the diagnosis of metabolic syndrome and non-alcoholic fatty liver disease: A population based study.

AIMS: The present study was carried out to determine the optimal cutoff points for homeostatic model assessment (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) in the diagnosis of metabolic syndrome (MetS) and non-alcoholic fatty liver disease (NAFLD). METHODS: The baseline data of 5511 subjects aged ≥18years of a cohort study in northern Iran were utilized to analyze. Receiver operating characteristic (ROC) analysis was conducted to determine the discriminatory capability of HOMA-IR and QUICKI in the diagnosis of MetS and NAFLD. Youden index was utilized to determine the optimal cutoff points of HOMA-IR and QUICKI in the diagnosis of MetS and NAFLD. RESULTS: The optimal cutoff points for HOMA-IR in the diagnosis of MetS and NAFLD were 2.0 [sensitivity=64.4%, specificity=66.8%] and 1.79 [sensitivity=66.2%, specificity=62.2%] in men and were 2.5 [sensitivity=57.6%, specificity=67.9%] and 1.95 [sensitivity=65.1%, specificity=54.7%] in women respectively. Furthermore, the optimal cutoff points for QUICKI in the diagnosis of MetS and NAFLD were 0.343 [sensitivity=63.7%, specificity=67.8%] and 0.347 [sensitivity=62.9%, specificity=65.0%] in men and were 0.331 [sensitivity=55.7%, specificity=70.7%] and 0.333 [sensitivity=53.2%, specificity=67.7%] in women respectively. CONCLUSION: Not only the optimal cutoff points of HOMA-IR and QUICKI were different for MetS and NAFLD, but also different cutoff points were obtained for men and women for each of these two conditions.

Reliability, validity, and sensitivity measures of expanded and revised version of the short-form McGill Pain Questionnaire (SF-MPQ-2) in Iranian patients with neuropathic and non-neuropathic pain.

OBJECTIVE: The aim of this study was to assess validity, reliability, and sensitivity of the Persian version of the short-form McGill Pain Questionnaire 2 (SF-MPQ-2) in patients with neuropathic and non-neuropathic pain. DESIGN: Beaton's guideline was used to translate and adapt the SF-MPQ-2 to Persian. SUBJECTS: One hundred eighty-four patients with subacute and chronic non-neuropathic pain and 74 patients with painful diabetic peripheral neuropathy (total 258) attending multidisciplinary pain clinic participated in the study. OUTCOME MEASURES: Internal consistency and intraclass correlation coefficient (ICC) were estimated for participants who had completed the questionnaire in the morning and evening of the first day. The visual analog scale (VAS) and the present pain intensity (PPI) were also recorded to test convergent validity of the questionnaire. Sensitivity to change was examined after a standard treatment and validated by means of the patient global impression of change (PGIC) in addition to VAS and PPI. Exploratory factor analysis (EFA) was used to find possible components. RESULTS: Cronbach's alpha was 0.906, which showed high internal consistency. ICC (0.941) revealed test-retest reliability. There was high correlation between the mean VAS and the mean total score (r = 0.926). Patients in different levels of PPI and PGIC exhibited significant differences among their mean total scores (P < 0.05). EFA revealed four components similar to the original SF-MPQ-2. CONCLUSION: The Persian translation of the expanded and revised version of the SF-MPQ-2 is a highly reliable, sensitive, and valid instrument to evaluate pain in patients with and without neuropathic etiology.

Prevalence of different electrocardiographic patterns in Iranian athletes.

To explore the abnormalities in Iranian athletes' electrocardiogram and find any relation with body fat. 239 international athletes were involved in this cross sectional study. Body-fat percentage and resting 12-lead ECGs were recorded from all participants. Of 239 participant athletes, 212 were male and 27 female. 60% of participants had sinus bradycardia. A total of 84% of the athletes demonstrated at least 1 abnormal ECG finding. Average values for the PR, QRS and QT intervals, P-wave duration and QRS axis were in normal range. Frequencies of various ECG abnormal findings in all athletes were as follows: right axis deviation 4.2%, left ventricular hypertrophy 6.2%, sinus arrhythmia 5.8%, right bundle branch block (RBBB) 24.2% (incomplete RBBB 16.8%, complete RBBB 7.4%), ST elevation 72.5%, prolonged QT interval 1.7%, T inversion 3.1% and Mobitz type I 1.2%. The athletes' ECG response to treadmill stress test was normal with no ischemia or arrhythmia. The means of BMI and body-fat percentage were 24.04 ± 3.5 kg/m² and 9.15 ± 2.12%, respectively. Pearson correlation coefficient between body-fat percentage and ST changes was 0.65 (P=0.008) in anterior leads and 0.198 (P=0.017) in lateral leads. Also, the correlation coefficient between the body fat percentage and right bundle branch block was 0.36 (P=0.013). The results of current study support the inclusion of ECG in athletes' cardiac screening before they engage in vigorous exercises in order to detect the potentially fatal arrhythmias.

Evaluation of QT Interval in ß Thalassemia Major Patients in Comparison with Control Group.

BACKGROUND: Cardiac complications are the primary cause of death in patients with b thalassemia major. QTc interval is an indicator of variability of ventricular repolarization and is supposed to be prominent in high risk patients. The aim of this investigation was to evaluate the relationship between QTc interval in ß thalassemia major in comparison with the control group. PATIENTS AND METHODS: Sixty ß thalassemia major and intermadia patients were enrolled in this analytical cross-sectional study. Thalassemia major and intermadia patients with no clinical symptoms of cardiac disease underwent echocardiographic and stress tests. QTc interval, blood pressure, heart rate, and average serum ferritin levels were measured. Statistical analysis was performed using version 15 SPSS. RESULTS: Although there was no clinical or echocardiographic sign of cardiac disease and QTc intervals measured before the test were not significantly different between patients and control group (421.7 ± 29.6 vs. 412.4 ± 28.2, P = 0.06), we found that, during stress test, QTc intervals (452.7 ± 30.8 vs. 410.2 ± 26.2, P < 0.001) and heart rate (105 ± 15.1 vs. 89.7 ± 12.3, P < 0.001) were notably greater in ß thalassemia major patients compared to the control group, respectively. CONCLUSION: We found augmented QTc intervals in this group of thalassemia major patients who have neither clinical nor electrocardiographic and gross echocardiographic signs of cardiac disease. QTc interval can be helpful in the cardiac assessment of thalassemia major patients.