NOVEL STRATEGIES TO IMPROVE METABOLIC PARAMETERS AND PRECONDITION DIABETIC HEARTS AGAINST ISCHEMIA/REPERFUSION INJURY

Insulin resistance and chronic hyperglycemia promote vascular damage, increase circulating levels of inflammatory cytokines and lead to increased morbidity and mortality. MicroRNAs (miRs) -103/107 have been shown to negatively regulate insulin sensitivity and glucose homeostasis. Based on complimentary binding profiles, the downstream target gene of miR-103/107 is caveolin-1 (Cav-1). We hypothesized that daily administration of the phosphodiesterase-5 inhibitor tadalafil (TAD) ± the curcumin analogue (HO-3867) will attenuate inflammation, improve metabolic parameters and reduce infarct size after ischemia/reperfusion injury (IRI). Furthermore, we propose that TAD therapy will reduce myocardial expression of miR-103/107 and increase mRNA and protein levels of its target gene, Cav-1. Leptin receptor null mice were randomized to receive daily injections of TAD (1mg/kg), HO-3867 (25mg/Kg), combination therapy, or control for 12weeks with weight and fasting glucose monitored weekly. Upon completion, cardiomyocytes were isolated from each group and were subjected to simulated ischemia and reoxygenation (SI/RO) for cell viability and reactive oxygen species (ROS) measurement. Another set were subjected to IRI in a Langendorff model. Plasma samples were taken to measure plasma concentrations of cytokines. For miR expression, total RNA was isolated from TAD and DMSO treated mice and was subjected to reverse transcription and real time PCR using miR assay probes to determine expression. TAD, HO-3867 and the combination of both attenuated fasting glucose levels, reduced myocardial infarct size after IRI and inflammatory cytokines when compared to control (p\u3c0.05 for each vs. control). Cardiomyocytes isolated from each treatment groups and subjected to SI/RO demonstrated reduced necrosis as shown by trypan blue exclusion assay, ROS generation, and improved mitochondrial membrane potential as compared to DMSO (control). Likewise, both mRNA and protein expression of Cav-1 were reduced in diabetic hearts but were significantly increased in TAD treated diabetic mice, which may be a mechanism to improve insulin signaling through downregulation of miR-103/107 and upregulation of Cav-1. These studies suggest that TAD alone or in combination may be a unique strategy to improve metabolic parameters and precondition diabetic hearts against IRI

Analysis and behavior of high-strength rectangular CFT columns

[EN] The current AISC Specification (AISC 360-16) specifies the material strength limits for concrete-filled steel tube (CFT) columns. According to AISC 360-16, the steel yield stress (Fy) for CFT columns should not exceed 525 MPa, and the concrete compressive strength (f’c) should not exceed 70 MPa. CFT columns are classified as high strength if either Fy or f’c exceeds these specified limits, and are classified as conventional strength if both Fy and f’c are less than or equal to the limits. Due to lack of adequate research and comprehensive design equations, AISC 360-16 does not endorse the use of high-strength materials for CFT columns. This paper makes a contribution towards addressing this gap using a two-step approach. The first step consists of compiling an experimental database of high-strength rectangular CFT column tests in the literature and evaluating the possibility of extending the current AISC 360-16 design equations to high-strength rectangular CFT columns. The second step consists of developing and benchmarking detailed 3D nonlinear finite element models for predicting the behavior of high-strength CFT columns from the database. The benchmarked models are being used to perform comprehensive parametric studies to address gaps in the database and propose design equations for high-strength rectangular CFT members, which will be part of a future paper.Lai, Z.; Varma, A. (2018). Analysis and behavior of high-strength rectangular CFT columns. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 245-252. https://doi.org/10.4995/ASCCS2018.2018.6957OCS24525

Synthesis Study: Repair and Durability of Fire-Damaged Prestressed Concrete Bridge Girders

Recent research results from INDOT research project SPR-4221 indicate that the damage to prestressed concrete bridge girders from an intense hydrocarbon fire is limited to concrete material degradation up to a depth of 1 inch from the surface. Additionally, concrete cracking and spalling occur in the fire-damaged region, but the structural strength (flexure and shear) of fire-exposed prestressed concrete bridge girders is not compromised. The findings open the possibility for repairing damaged bridge girders and answers questions regarding the durability of damaged-unrepaired and damaged-repaired girders

Compression Testing and Failure Modes of Steel-Concrete Composite (SC) Structures for Nuclear Containment

Although being able to provide much cleaner power than burning coal and other fossil fuels, nuclear power plants are still a tough sell to the general public due to their history of being spontaneously dangerous. The containment structures surrounding these nuclear plants, however, can play a huge role in reducing the risks associated with them. Relatively new designs for these containment assemblies, known as SC (steel-concrete composite) structures, aim to increase the strength and durability of the containment facilities while keeping costs down. By varying the spacing between shear studs, the ratio of concrete to steel, and the ratio of width to thickness, many different properties of these structures change in a way that determines overall strength and failure mode (i.e. global vs. local buckling). In this research, several scaled-down specimens mimicking a theoretical SC wall were put into compression tests that yielded results exhibiting their behaviors under hypothetical loads that the structure may encounter. By observing the specimens with a high-speed camera (complete failure is observed over the course of a couple of seconds), results such as the failure mode and compressive strengths were observed. These findings will supply a portion of the research and information that is necessary in order to continue this design’s development into nuclear-containment facilities. Research on the design must be continued to find relationships between variables that would allow an engineer to idealize the structural design for their specific needs. Such is necessary for their future implementation in real structures

Finite Element Analysis of Bolted Connections under Fire

Over the course of human history, fire disasters are one of the major catastrophes that causes loss of lives and properties. In order to ensure building safety against fire, civil engineers seek to understand the behavior of structures at high temperatures. Moreover, they need to study the behavior of bolted connections, given the important role it plays in steel structures. Sarraj (2007) proposed a plate-bearing computational model used to describe this behavior; however, it has never been experimentally verified. Prior to this specific project, a series of single-bolted connection tests at 400°C and 600°C were conducted in the Bowen Laboratory at Purdue University. In this project, the experimental data from these tests was used to benchmark a finite element (FE) model. Additional finite element analysis was conducted based on 16 double-splice joint specimens tested at Chiba University, Japan. The purpose of the analysis was to further verify the accuracy of the previous FE model. Once the FE model was well benchmarked, a parametric study was conducted afterwards to identify other parameters that could affect the plate-bearing behavior of bolted connections. Comparison of load-deformation plots between experimental and numerical results showed that the model is capable of predicting the behavior of bolted connections with good precision. The results of the parametric study indicated that bolt size and loading angle could also affect the plate-bearing behavior in fire. Further work is necessary to verify the accuracy of Sarraj’s model, and to conduct experimental tests on bolted connections at other temperature levels

Seismic Design Coefficients for SpeedCore or Composite Plate Shear Walls - Concrete Filled (C-PSW/CF)

This report summarizes the results from FEMA P695 analytical studies conducted to verify the seismic design factors for composite plate shear walls – concrete filled (C-PSW/CF), also referred to as Speedcore. ASCE 7-16 provides the seismic design factors, which include the seismic response modification factor, R, deflection amplification factor, Cd, and overstrength factor, Ωo, for various approved seismic systems. C-PSW/CFs are assigned a response modification factor of 6.5, a deflection amplification factor of 5.5, and an overstrength factor of 2.5 for C-PSW/CFs. These seismic design factors were selected based on the seismic performance of similar structural systems and engineering judgment of the committee. This analytical study investigated and verified the appropriateness of these seismic design factors for walls with flange plates as boundary elements. Four planar (3-story, 6-story, 9-story, and 12-story) and three C-shaped (15-story, 18-story, and 22-story) C-PSW/CF walls were analyzed following the FEMA P695 procedure. This procedure included development of representative planar and C-shaped C-PSW/CF archetypes, calibration of numerical models for these archetypes, and evaluation of nonlinear static (pushover) and incremental dynamic (time history) analyses. The results indicate that seismic design coefficients of R = 6.5, Cd = 5.5, and Ωo = 2.5 appropriately quantify the seismic performance of C-PSW/CF with boundary elements. Walls without any boundary elements or closure plates are not recommended for seismic design based on supplementary analytical studies

Post-Earthquake Fire Assessment of Steel Buildings

Resilience of structural systems after hazardous events is a crucial concern of building design. An abundance of research has focused on hazards such as seismic and fire separately. This project conducted a multi-hazard study on steel buildings considering both seismic and fire damage. A literature review of the behavior of steel-framed buildings due to fires after earthquakes, known as post-earthquake fires (PEF), is offered. The new PEF methodology, delivered in this study, starts with creating a three dimensional (3D) model of the examined steel building using the finite element method software, ABAQUS. Next, varying intensities of seismic and fire hazards were applied to the building models. Incremental dynamic analyses (IDA) were conducted to examine the progression of damage as peak ground accelerations increase. Similarly, incremental fire analyses (IFA) involved scaling the peak fire temperature and recording the vertical story deflection. Three primary failure modes were observed: compartment failure, column failure and bay failure. Preliminary results show that gravity columns are the most vulnerable component within the structure, regardless of seismic damage. Recommendations for improving building resilience are provided for future examination

Efficient Load Rating and Quantification of Life-Cycle Damage of Indiana Bridges Due to Overweight Loads

In this study, a computational approach for conducting durability analysis of bridges using detailed finite element models is developed. The underlying approach adopted is based on the hypothesis that the two main factors affecting the life of a bridge structure are the level of repetitive loading it sustains and the natural condition of the bridge that may be thought of as a combined effect of both, physical processes in the environment that cause deterioration and any maintenance activity undertaken to thwart such processes. Detailed finite element models of representative bridges are developed and subjected to a set of representative traffic loads repeatedly. Finite element model updation is used to characterize the evolution of damage over the lifetime of a bridge and real-life data from inspection reports of bridges is used to calibrate the durability models developed. The results of this approach may be used to evaluate the permit fee structure for overweight trucks and make informed decisions for asset management of the bridges in INDOT’s inventory

Assessment of medical students by OSPE method in pathology

ABSTRACT: Objective structured practical examination (OSPE) is a practical exam system wherein there is a series of stations at which students work through tasks designed to test various skills and are tested using agreed check lists with observers sitting at some of the stations. It has been found to be objective, valid and reliable. It also eliminates examiner bias. The purpose of this study is to introduce OSPE both as an evaluation and a teaching tool and to draw attention to its advantages and disadvantages. We designed an OSPE that tested all the above objectives satisfactorily. The OSPE exam was conducted in the department of pathology during the second internal assessment of the students. This method was the compared with the conventional method of practical exam conducted during the first internal assessment of the same batch of students. The results showed that OSPE tests different desired components of competence better. It is an objective, valid and reliable method and gets rid of variation due to examiner bias. It has a better discrimination index on merit. Interpretative exercises are the most relevant part and deserve the lion’s share of total marks. Students feel more comfortable and less stressed to perform the exam. KEYWORDS: Objective structured practical examination; Medical education; Teaching methodology; PathologyInternet Journal of Medical Update 2012 January;7(1):2-

B-type natriuretic peptide levels and its correlation with left ventricular functions and heart failure in patients of acute coronary syndromes

Background: This study was designed to measure levels of B-type natriuretic peptide (BNP) across entire spectrum of acute coronary syndrome (ACS) and to find its correlation with left ventricular functions and heart failure.Methods: We measured BNP levels at baseline in 100 consecutive patients between 24-96 hours after the onset of ischemic symptoms in patients of ACS. Echocardiography was performed in all patients between day 2-5 after the index diagnosis and stabilizing the patients.Results: The BNP levels were raised across the entire spectrum of ACS, with levels (>80 pg/ml) in 32.2% of patients with ST segment-elevation myocardial infarction (STEMI), in 24% with non-ST segment-elevation myocardial infarction (NSTEMI), and in 16.6% with unstable angina (UA) respectively. High BNP levels were associated with greater increase in LV end-systolic volumes (r=+0.545, p<0.001) (LVESV) and end-diastolic volumes (LVEDV) (r=+0.336, p<0.001). There was a negative correlation between BNP levels and left ventricular ejection fraction (LVEF) (r=-0.394, p<0.002). BNP levels were significantly raised (156.0±45.1 vs 57.7±18.3 pg/ml, p<0.02) in patients developing symptomatic clinical heart failure, irrespective of LVEF ≤40%.Conclusions: Integrated use of echocardiography and BNP levels provide powerful incremental assessment of cardiac functions, clinical status, and outcome across the entire spectrum of acute coronary syndromes (ACS). Increased BNP levels are associated with progressive ventricular dilatation, LV-dysfunction, development of clinical heart failure and is associated with poor prognosis in patients of ACS