Assessment of mechanical properties and microstructure characterizing techniques in their ability to quantify amount of cold work in 316l alloy

Stress corrosion cracking (SCC) behavior is a matter of concern for structural materials, namely, stainless steels and nickel alloys, in nuclear power plants. High levels of cold work (CW) have shown to both reduce crack initiation times and increase crack growth rates. Cold working has numerous effects on a material, including changes in microstructure, mechanical properties, and residual stress state, yet it is typically reported as a simple percent change in geometry. There is need to develop a strategy for quantitative assessment of cold-work level in order to better understand stress corrosion cracking test data. Five assessment techniques, commonly performed alongside stress corrosion cracking testing (optical microscopy (OM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), tensile testing, and hardness testing) are evaluated with respect to their ability to quantify the level of CW in a component. The test material is stainless steel 316L that has been cold-rolled to three conditions: 0%, 20%, and 30% CW. Measurement results for each assessment method include correlation with CW condition and repeatability data. Measured values showed significant spatial variation, illustrating that CW level is not uniform throughout a component. Mechanical properties (tensile testing, hardness) were found to correlate most linearly with the amount of imparted CW

Oxidant-NO dependent gene regulation in dogs with type I diabetes: impact on cardiac function and metabolism

<p>Abstract</p> <p>Background</p> <p>The mechanisms responsible for the cardiovascular mortality in type I diabetes (DM) have not been defined completely. We have shown in conscious dogs with DM that: <it>1</it>) baseline coronary blood flow (CBF) was significantly decreased, <it>2</it>) endothelium-dependent (ACh) coronary vasodilation was impaired, and <it>3</it>) reflex cholinergic NO-dependent coronary vasodilation was selectively depressed. The most likely mechanism responsible for the depressed reflex cholinergic NO-dependent coronary vasodilation was the decreased bioactivity of NO from the vascular endothelium. The goal of this study was to investigate changes in cardiac gene expression in a canine model of alloxan-induced type 1 diabetes.</p> <p>Methods</p> <p>Mongrel dogs were chronically instrumented and the dogs were divided into two groups: one normal and the other diabetic. In the diabetic group, the dogs were injected with alloxan monohydrate (40-60 mg/kg iv) over 1 min. The global changes in cardiac gene expression in dogs with alloxan-induced diabetes were studied using Affymetrix Canine Array. Cardiac RNA was extracted from the control and DM (n = 4).</p> <p>Results</p> <p>The array data revealed that 797 genes were differentially expressed (P < 0.01; fold change of at least ±2). 150 genes were expressed at significantly greater levels in diabetic dogs and 647 were significantly reduced. There was no change in eNOS mRNA. There was up regulation of some components of the NADPH oxidase subunits (gp91 by 2.2 fold, P < 0.03), and down-regulation of SOD1 (3 fold, P < 0.001) and decrease (4 - 40 fold) in a large number of genes encoding mitochondrial enzymes. In addition, there was down-regulation of Ca²⁺cycling genes (ryanodine receptor; SERCA2 Calcium ATPase), structural proteins (actin alpha). Of particular interests are genes involved in glutathione metabolism (glutathione peroxidase 1, glutathione reductase and glutathione S-transferase), which were markedly down regulated.</p> <p>Conclusion</p> <p>our findings suggest that type I diabetes might have a direct effect on the heart by impairing NO bioavailability through oxidative stress and perhaps lipid peroxidases.</p

Quiescence and γH2AX in neuroblastoma are regulated by ouabain/Na,K-ATPase

Cellular quiescence is a state of reversible proliferation arrest that is induced by anti-mitogenic signals. The endogenous cardiac glycoside ouabain is a specific ligand of the ubiquitous sodium pump, Na,K-ATPase, also known to regulate cell growth through unknown signalling pathways. To investigate the role of ouabain/Na,K-ATPase in uncontrolled neuroblastoma growth we used xenografts, flow cytometry, immunostaining, comet assay, real-time PCR, and electrophysiology after various treatment strategies. The ouabain/Na,K-ATPase complex induced quiescence in malignant neuroblastoma. Tumour growth was reduced by >50% when neuroblastoma cells were xenografted into immune-deficient mice that were fed with ouabain. Ouabain-induced S-G2 phase arrest, activated the DNA-damage response (DDR) pathway marker γH2AX, increased the cell cycle regulator p21Waf1/Cip1 and upregulated the quiescence-specific transcription factor hairy and enhancer of split1 (HES1), causing neuroblastoma cells to ultimately enter G0. Cells re-entered the cell cycle and resumed proliferation, without showing DNA damage, when ouabain was removed. Conclusion: These findings demonstrate a novel action of ouabain/Na,K-ATPase as a regulator of quiescence in neuroblastoma, suggesting that ouabain can be used in chemotherapies to suppress tumour growth and/or arrest cells to increase the therapeutic index in combination therapies

Quantitative impacts of regenerative vibration and abrasive wheel eccentricity on surface grinding dynamic performance

In grinding, regenerative vibration and forced vibration due to grinding wheel eccentric rotation are main excited-vibration sources that interact with grinding material removal mechanism. In the paper, instantaneous undeformed chip thickness in down-grinding cutting phase may consist of two components, i.e. linear kinetic thickness and nonlinear dynamic thickness. Considering abrasive grit-workpiece interaction in the grinding contact zone, the grinding vibration system is presented by a new set of differential equations of two degrees of freedom (DOF) with a close-loop feedback control system models. Conventional grinding control parameters, including wheel spindle speed, work-speed in feed direction and radial cutting depth, are often regarded as linear constants in many existing simplified models. When considering time delay, they can be transferred to nonlinear variables, so the capability of prediction and the accuracy of solution of the grit-workpiece dynamic performance are improved. Based on quantitative comparison of force and vibration magnitudes, the influence of the eccentric rotation of abrasive wheel and the negative rake angle of working grit cutting edges on grinding performance are demonstrated in the paper. © 2018 Springer-Verlag London Ltd., part of Springer Natur

Saving Human Lives: What Complexity Science and Information Systems can Contribute

We discuss models and data of crowd disasters, crime, terrorism, war and disease spreading to show that conventional recipes, such as deterrence strategies, are often not effective and sufficient to contain them. Many common approaches do not provide a good picture of the actual system behavior, because they neglect feedback loops, instabilities and cascade effects. The complex and often counter-intuitive behavior of social systems and their macro-level collective dynamics can be better understood by means of complexity science. We highlight that a suitable system design and management can help to stop undesirable cascade effects and to enable favorable kinds of self-organization in the system. In such a way, complexity science can help to save human lives.Comment: 67 pages, 25 figures; accepted for publication in Journal of Statistical Physics [for related work see http://www.futurict.eu/

Sustainability indicators for grinding applied to dressing strategies

Growing environmental awareness leads production engineers to focus increasingly on energy and material efficiency of manufacturing processes. However, only a few holistic approaches have been applied on the manufacturing process level and they often disregard product quality. In this study, sustainability indicators for the discrete manufacturing process of grinding are defined and discussed. Various temporal and spatial boundaries for the sustainability analysis are evaluated with regard to their effect on the results. Selected indicators, here energy and waste intensity, are then used to evaluate different dressing strategies in a case study. This study highlights the challenges in setting the boundaries for a sustainability analysis and stresses the importance of clearly defining these in research papers. © 2014 by ASME

Sustainability indicators for grinding applied to dressing strategies

Growing environmental awareness leads production engineers to focus increasingly on energy and material efficiency of manufacturing processes. However, only a few holistic approaches have been applied on the manufacturing process level and they often disregard product quality. In this study, sustainability indicators for the discrete manufacturing process of grinding are defined and discussed. Various temporal and spatial boundaries for the sustainability analysis are evaluated with regard to their effect on the results. Selected indicators, here energy and waste intensity, are then used to evaluate different dressing strategies in a case study. This study highlights the challenges in setting the boundaries for a sustainability analysis and stresses the importance of clearly defining these in research papers. © 2014 by ASME

Shigley Hauler - A competitive project illustrating basic machine design principles

By requiring students to meet demanding functional specifications using limited resources, the competitive Shigley Hauler project offers undergraduate students practical "hands-on" experience in the design, fabrication, and testing of mechanical systems. The project imparts a thorough experiential understanding of the key principles that govern the selection and integration of basic machinery components - gears, shafts, bearings, DC motors, etc. - into a robust and efficient working system. The Shigley Hauler project has been successfully incorporated into the mechanical engineering curriculum at UC Davis for more than a decade, and its pedagogical and motivational value is corroborated by student feedback. The project is run within a 10-week timeframe, and entails only modest costs for the instructor and student teams

Learning benefits by integrating design, manufacturing, and testing in a course for compressible flow visualizations

Although engineering is by nature an applied and interdisciplinary field, courses in engineering can lead even the best students to develop knowledge that is disconnected from other related fields and from conditions of application. This paper describes an innovative undergraduate course that integrated the theory of shock waves, computational modeling, experimental testing, and science of sustainable manufacturing. The course supported better visualization of mechanical and aerospace engineering phenomena, such as shock waves in supersonic gas flows, by utilizing the hydraulic analogy of shallow water and a simple water table. Airfoil design and manufacture were integrated through aerospace and manufacturing theory and application. For the first course offering, student learning was assessed with regard to their views of engineering, learning experience, and transfer of learning. The course proved to increase self-efficacy as engineers, as well as their self-reported confidence in working comfortably on multi-disciplinary teams. Furthermore, scenario-based assessments confirmed that the students were able to integrate aerospace and manufacturing theory and application within new scenarios

Molecular dynamics simulations of single grain pure aluminum in a vice fixture for nanomanufacturing applications

Although nano and macro manufacturing encompass two different scales of machining, investigating both is essential for understanding machining distortions and deformations. In both macro and nano fabrication, the fixture is the primary means of securing the workpiece in place while performing the manufacturing operations. Understanding the fixture design is a critical aspect relating the two different scales of manufacturing. This paper describes a method involving atomistic simulation for understanding machining distortions for the macro scale by investigation of nano machining and work holding devices. This research aims to help bridge the knowledge gap in manufacturing of macro and nano scale applications. The simulations performed showed that the fixture influences the machining distortions and the critical stress concentrations on the workpiece