Investigations on force generation and joint properties of dissimilar thickness friction stir corner welded AA 5086 alloy

The force generation, joint mechanical and metallurgical properties of friction stir corner welded non-heat treatable AA 5086 aluminum alloy are investigated in this paper. The friction stir welding process is carried out with the plate thicknesses of 6 mm and 4 mm. The welding speed, tool rotational speed and tool plunge depth were considered as the process parameters to conduct the welding experiments. The machine spindle motor current consumption and tool down force generation during friction stir welding were analyzed. The microstructures of various joint regions were observed. The tensile samples revealed the tensile strength of 197 MPa with tool rotational and welding speeds of 1,000 rev/min and 150 mm/min respectively, which is 78 % of parent material tensile strength. A maximum micro hardness of 98 HV was observed at thermomechanically joint affected zone, which was welded with tool rotation of 1,000 rev/min and welding speed of 190 mm/min

Septal Pouch in the Left Atrium A New Anatomical Entity With Potential for Embolic Complications

ObjectivesThe purpose of this study was to develop a better understanding of the pathophysiology of the condition, we studied the patterns by which the septum primum (SP) and septum secundum (SS) fuse.BackgroundA patent foramen ovale (PFO) is a communication across the interatrial septum between a nonadherent SP and SS and is considered to be a risk factor for serious clinical syndromes.MethodsWe examined the interatrial septum in 94 randomly selected autopsied hearts, with a focus on the SP and SS and the patterns by which the 2 structures fuse.ResultsOf the 94 specimens that were suitable for analysis, 26 (27.66%) had a PFO. Of the remaining 68 hearts, complete fusion of the SP and SS along the entire zone of overlap was seen in 27 (28.7%) hearts. In the remaining 41 hearts (60.29%), a PFO was absent, but incomplete fusion of the SP and SS was seen. Of 41 hearts, 37 (90%) had a septal pouch that opened into the left atrial (LA) cavity. Four hearts (10%) had a pouch accessible from the right atrium. Hearts with left-sided pouches tended to be younger (50 ± 18 years of age) than hearts where there was complete fusion (age 63 ± 23 years) (p = 0.06).ConclusionsOur data suggest that when a foramen ovale closes spontaneously, the SP and SS fuse initially at the caudal limit of the zone of overlap of the 2 structures. This incomplete fusion results in a pouch that, in the majority of instances, communicates with the LA cavity

PNEUMATIC ARTIFICIAL MUSCLE CONSTRUCTION USING NATURAL FIBER "SILK" FOR BIO-MEDICAL ENGINEERING

The objective of this project is to design and develop a desirable low cost and lightweight Pneumatic Artificial Muscle PAM) actuator using different materials. In this work, the studies are conducted to find the effect of various braided materials such as nylon, steel and Natural Fiber (Silk). The analysis is carried out on actuators of having constant longitudinal length of 140 mm varying the diameter namely 15 mm, 20 mm and 30 mm. The experiment was set up to collect the length and force variation data of the artificial muscle with various compressed air pressures. The force generated by PAM purely depends on the rate of pressure added and removal from the actuator and is contractile in nature upon inflation. PAM actuators find wide applications in various facets of robotic equipments and industrial automation. They are easy to manufacture, low cost and can be integrated with human operations without any large scale safety requirements. The innovative idea of using silk as braided sleeves has many advantages: It is naturally available with higher stiffness and allowable tensile stress is higher than that of nylon and steel. At a low load actuation of 10 N, the 20 mm diameter the silicon(ny1on braided sleeve) actuator contracts 18.45 % , silicon(stee1 braided sleeve) actuator contracts 20 % and whereas silicon(si1k braided sleeve) actuator shows 17.90 % contraction at a inlet pressure of 3 bars. The movement of this actuator is soft which is similar to the human muscle; hence it is preferred for usage in bio medical application

Violent Hiccups: An Infrequent Cause of Bradyarrhythmias

A hiccup, or singultus, results from a sudden, simultaneous, vigorous contraction of the diaphragm and inspiratory muscles, accompanied by closure of the glottis. Hiccups can be associated with bradyarrhythmias. The mechanism of this phenomenon is likely hiccup-induced Valsalva maneuver and increased parasympathetic tone. We present a case of a patient with violent hiccups producing a bradyarrhythmia

Anatomical Basis for the Mobility of the Esophagus: Implications for Catheter Ablation of Atrial Fibrillation

We present autopsy data from a patient that illustrates the anatomical factors that allow the esophagus to be a mobile structure, especially with respect to the posterior left atrial wall

Review of the Gender and Social Impacts of Improved Seed Technology in Developing Countries: Policy Implications

Experts have acknowledged the limits to growth that the processes of climate change, population expansion, and resource depletion will place on agricultural producers in the 21st century (FAO 2012). In response, scientists are employing biotechnology to create new improved seed varieties. However, developing improved seed technology (IST) involves complex and controversial issues that span across disciplines in the biological and social sciences (see Box 1). In this policy brief, we emphasize the need to better examine the gender and social impacts of advancements in seed technology. Based on a detailed review of the literature, we determine that despite recent advancements, women and small farmers still face distinct challenges, particularly in developing countries. For example, farmers need to access a variety of resources to use IST but access to those resources is restricted by gender and class. Formal regulatory and property rights agreements can further hamper women’s agricultural potential. We suggest that policy makers (1) take into account existing gender and class inequalities in agricultural systems when crafting IST regulations, (2) work to understand how marginalized farmers may be lost in the gap between public and private IST distributions systems, (3) strive to increase transparency in how IST innovations are created and regulated, and (4) promote and support interdisciplinary research teams

Intellectual Property Rights for New Seed Technologies: Balancing Farmers’ and Breeders’ Rights

Many cite improved seed technologies as vital to addressing the challenge of food insecurity, especially when faced with combined stresses of global climate change, population growth, and natural resource depletion (Anthony and Ferroni 2012; Lipton 2007). As improved seeds find their way into the developing world, policymakers are struggling to find the appropriate institutional mechanisms to regulate their creation and use. Arguments over intellectual property rights (IPR) are central to this debate. Some activists in the Global South are distrustful of any IPR regime that creates private ownership over seeds, whereas international financial institutions such as the World Trade Organization (WTO) encourage stronger IPR protections for commercial seed breeders creating new plant varieties. Policymakers face two conflicting imperatives in making these policies: (1) promote improved seed development and distribution in ways that will encourage new seed innovations and protect the interests of commercial breeders and (2) protect the interests of farmers who serve as both a source of vital germplasm and as the potential users of these improved seeds. In this policy brief, we consider the sources of these conflicting imperatives for developing nations to protect the rights of commercial plant breeders and small farmers, as well as some examples of national policies trying to balance those demands

MULTI-RESPONSE OPTIMIZATION OF PROCESS PARAMETERS BY TAGUCHI GREY RELATIONAL ANALYSIS FOR DISSIMILAR THICKNESS FRICTION STIR PROCESS CORNER WELD AA5086 ALLOY

This paper presents the multi-response optimization of friction stir corner welding process for dissimilar thickness AA5086 aluminium alloy plates. The corner joint of AA5086 aluminium alloy plates of thicknesses of 6 mm and 4 mm was welded by Friction Stir Welding (FSW) process. The FSW experiments were conducted agreeing to the L9 orthogonal array. Three FSW process parameters: tool traverse speed (100, 150 and 190 mm/min), rotational speed (900, 1000 and 1100 rev/min), and plunge depth (0.1, 0.2, and 0.3 mm) were related with weld tensile strength and hardness. The Analysis of Variance (ANOVA) was used to determine the percentage contribution of each input parameter on the weld quality. Taguchi Grey Relational Analysis is used to optimize and order the FSW process parameters. Conferring to the results of the analyses, the optimal welding condition was determined as 1000 rev/min for tool rotational speed, 150 mm/min for traverse speed and 0.1 mm for tool plunge depth. The percentage contribution of the traverse speed (54%) revealed a significant influence compared to tool rotational speed (21%) and plunge depth (13%). The microstructures of various zones were observed and analysed. Tensile tests were conducted and the fracture was observed at heat affected zones for all the joints. Current consumption, temperature distribution, and force generation during friction stir welding were acquired and analysed.

Prolongation of the QTc Interval Is Seen Uniformly During Early Transmural Ischemia

ObjectivesIn order to more clearly understand the electrocardiographic manifestations of early transmural ischemia, we studied electrocardiograms (ECGs) in patients undergoing balloon angioplasty.BackgroundDecisions regarding reperfusion strategies in patients with acute myocardial infarction rely largely on the presence of ST-segment elevation (STE) in the ECG, consequently with significant limitations. Studies of the “ischemic cascade” show that ST-segment changes occur well after the onset of wall motion abnormalities.MethodsWe prospectively analyzed ECGs obtained at 20-s intervals in 74 patients undergoing elective balloon angioplasty. The ECGs were analyzed using 3 methodologies. In 74 patients, the ST-segment, the T-wave, and the QT-interval were analyzed using the MUSE (General Electric HC, Menomonee Falls, Wisconsin) automated system (MUSE). Fifty patients were also analyzed using the Interval Editor automated system (IE; General Electric HC). In 20 patients, measurements were made manually.ResultsTransmural ischemia prolonged the QTc interval (using the Bazett’s formula) in 100% of patients. In all 74 patients analyzed with MUSE, QTc interval prolonged from 423 ± 25 ms to 455 ± 34 ms (p < 0.001). In the 50 patients analyzed with IE, QTc interval prolonged in 50 of 50 (100%) patients (from 424 ± 27 ms to 458 ± 33 ms [p < 0.001]). Mean time to maximal QTc interval prolongation, changes in T-wave polarity, ≥1 mm STE, and ST-segment depression (STD) were 22, 24, 29, and 35 s, respectively. Although QTc interval prolonged in 100% of patients, T-wave changes, STE, and STD (≥1 mm) occurred in 7%, 15%, and 7%, respectively.ConclusionsThe QTc interval prolongs in 100% of patients with early transmural ischemia. When compared with clinically accepted indexes of transmural ischemia (i.e., STD and STE [≥1 mm]) it is the earliest ECG abnormality