118 research outputs found
On sub-surface stress caused by contact roughness in compressible elastic solids
No full textContact between elastic bodies with self-affine rough surfaces is mostly studied with a focus on determining surface fields, despite body fields are of great importance to establish, for instance, when and where elasticity breaks down. This work aims at analyzing the effect of contact roughness on the body fields of compressible frictionless solids modeled using Green's function molecular dynamics. Although area-load curves are insensitive to changes in the Hurst exponent as long as they are correctly normalized and are clearly not affected by compressibility, the Von-Mises stress is found to depend on both Hurst exponent and Poisson's ratio.(OLD) MSE-7Team Marcel Sluite
Dravidian Futurities: A Creative Process
No full textIn this article, author and artist Meena Murugesan analyzes their creative process and research in the making of Dravidian Futurities, a multi-channel video installation with live performance. Methodologies of auto-ethnography, visual aesthetics, embodied movement practices, Tamil historiographies, queer futurities, caste analysis, and poetics are applied to treat the issues at hand. Dravidian Futurities draws connections between communities of South Indian and Sri Lankan Shudra and Dalit caste backgrounds, Dravidian, and Afro-Indian peoples, depending on the historical era examined. As someone of the Shudra caste, the author draws connections between agriculture, land, and earth, as being rooted in Shudra identities, and in opposition to brahminical systems. Therefore, the movement forms of somatics, improvisation, and nature-based embodiment practices are investigated as possible embodied inroads to grapple with caste within brahminized bharatanatyam. Notions of futurity and place-making are unearthed from the depths of the Indian Ocean with a hypothetical sunken landmass called Lemuria or Kumari Kandam that might have once connected South India, Sri Lanka, and Madagascar. Dravidian Futurities also dreams into existence this speculative landmass as a possible utopia we might co-build, similar to that which Dalit mystic saint Guru Ravidas imagined five hundred years ago with Begumpura (“land without sorrow”) as a casteless, stateless utopia
Correction: Murugesan, M., et al. Johnson Cook Material and Failure Model Parameters Estimation of AISI-1045 Medium Carbon Steel for Metal Forming Applications. Materials 2019, 12, 609
No full textThe author wishes to make the following corrections to this paper [...
The Role of HOXA1 in oncogenic transformation of the human mammary epithelial cell
No full textFull text is available to authenticated members of The University of Auckland only.Expression of homeobox AI. (HOXAI) results in oncogenic transformation of immortalized human mammary epithelial cells with aggressive tumor formation in vivo. However, the mechanisms by which HOXAl mediates oncogenic transformation is not well defined. The primary aim of this thesis was to delineate the downstream
effectors and signal transduction pathways utilized for HOXAl mediated oncogenic transformation of human mammary epithelial cells. To identify molecules that could potentially be involved in HOXAl-mediated oncogenic transformation, microarray analysis was utilized to characterize and compare the gene expression pattern in response to forced expression or depletion of HOXAl in human mammary carcinoma cells. Gene expression profiling identified that genes involved in the p44/42 mitogenactivated protein (MAP) kinase activation pathway (GRB2, MAP kinase kinase (MEKI) and SDFRl) or p44/42 MAP kinase-regulated genes (IER3, EPASl, PCNA and catalase) are downstream expression targets ofHOXAl. Expression of exogenous HOXAl increased GRB2 and MAP kinase kinase (MEKl) mRNA and protein expression and increased p44/42 MAP kinase phosphorylation, activity and Elk-1- mediated transcription. Use of a MEKl inhibitor demonstrated that increased p44/42 MAP kinase activity is required for the HOXAl-mediated increase in cell proliferation, survival, oncogenicity and oncogenic transformation. Thus, modulation
of the p44/42 MAP kinase pathway is one mechanism by which HOXAl mediates oncogenic transformation of the human mammary epithelial cell. However, treatment with a MEKl inhibitor did not completely prevent HOXAl stimulated oncogenic transformation, suggestive of the involvement of additional signal transduction pathways. Here I report that forced expression of HOXAl in immortalised human mammary
epithelial cells significantly increased levels of STAT3/5A/5B mRNA by transcriptional upregulation. Protein levels of STAT3/5B but not STAT5A, and phosphorylation level of STAT3/5B protein were significantly increased by forced expression of HOXAl. Forced
expression of STAT3 or. STATSB was sufficient to oncogenically transform an immortalised human mammary epithelial cell. Antagonism of STAT3 or STATSB activity with dominant negative STAT3 or STATSB accordingly abrogated the ability of HOXAl to stimulate cell proliferation, survival, oncogenic transformation and generation of large disorganized multiacinar structures. These results suggest that modulation of the p44/42 MAP kinase, STAT3 and STAT5B pathways are pivotal down stream mechanisms, through which HOXAl mediates oncogenic transformation of human mammary epithelial cell
Entomopathogenic Fungi for the Management of Calopepla leayana on Gmelina arborea
No full textEntomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae were isolated and identified as natural pathogens of Calopepla leayana. Both the species of fungi were effective against the larval and adult stages of C. leayana causing white and green muscardine diseases respectively. It was also found that B. bassiana was more pathogenic to the pest as compared to M. anisopliae. The susceptibility of larvae and adults was negatively associated with the age and positively associated with the fungal spore concentration. In all the stages from I instar to adult, the highest mortality was observed in 10% of 1x109 spores/ml concentration of B. bassiana among 1, 2.5, 5 & 10% of 1x109 spores/ml concentration. It was also reflected in probit analysis that the concentration of spores required to kill fifty percent of the population was ranges from 0.09% to 5.98% of 1x109 spores/ml concentration of B. bassiana and 1.02% to 9.72% of 1x109 spores/ml concentration of M. anisopliae. The larvae of I instar have shown highest mortality, which gradually decreased with the increase in age or decrease in the concentration of fungal spores. Mass production of B. bassiana using different substrates was attempted to harvest ample amount of spores. This study revealed that spore production was directly proportional to the mycelial weight and incubation period. From the seven substrates tested, wheat flour was identified as one of the suitable substrates for the mass production of B. bassiana. A field trial was conducted to test their efficacy under field conditions. 72-93% mortality was observed in field conditions.-----------------------------------------------------------------------------------------------------Division of Bioprospecting, Institute of Forest Genetics and Tree Breeding, Coimbatore-641002, Tamilnadu, India*Corresponding author, Email: [email protected] This Article As: N. Senthilkumar and S. Murugesan. 2010. Entomopathogenic Fungi for the Management of Calopepla leayana on Gmelina arborea. J. Ecobiotechnol. 2(3): 01-0
Intraperitoneal bilirubin administration decreases infarct area in a rat coronary ischemia/reperfusion model
No full textBilirubin was previously considered a toxin byproduct of heme catabolism. However, a mounting body of evidence suggests that at physiological doses, bilirubin is a powerful antioxidant and anti-atherosclerotic agent. Recent clinical studies have shown that human beings with genetically-induced hyperbilirubinemia (Gilbert Syndrome) are protected against coronary heart disease. The purpose of this study was to investigate whether administration of exogenous bilirubin to normal rats would convey similar protective effects in an experimental model of coronary ischemia. We hypothesized that intraperitoneal bilirubin administration 1 h before injury would decrease infarct area and preserve left ventricular (LV) systolic function when compared to non-treated rats. Coronary ischemia was induced by temporary (30 min) ligation of the left anterior descending coronary artery in control or bilirubin treated rats, followed by a 1-h period of reperfusion. LV function was estimated by measurements of fractional shortening (FS) and fractional area shortening using echocardiography. LV function decreased in both experimental groups after ischemia and reperfusion, although in bilirubin-treated rats FS was less depressed during the period of ischemia (18.8 vs. 25.8%, p = 0.034). Infarct size was significantly reduced in the bilirubin treated group compared to the non-treated group (13.34 vs. 25.5%, p = 0.0067). Based on the results of this study, bilirubin supplementation appears to provide significant decrease in infarct size although protective effects on LV function were noted only during the period of ischemia. This result also suggests that lipid soluble antioxidant bilirubin prevents the oxidation of cardiolipin and decreases the infarct size in the heart during ischemia
3-D Green's function molecular dynamics for solids with generic elastic properties
No full textVarious contact mechanics theories have been developed in recent years. The most popular are the statistical asperity theories of the type of Greenwood and Williamson and Persson’s theory, which treats self affine rough surfaces. The latter theory includes roughness at all length scales as well as long range elastic interactions. However, it is exact only at full contact conditions, which are often met by rubbers but not by metals. With metals in mind, we here use Green’s function molecular dynamics (GFMD) simulations to assess the validity of Persson’s theory at small loads, therefore small contact areas. GFMD is a boundary-value method which allows for ultra fine discretization of rough surfaces since it is computationally very efficient, and treats interfacial contact using interatomic potentials. To date, the GFMD method was only used in 3-D for modelling the normal loading of rough elastic semi-infinite incompressible (Poisson's ratio = 0.5) solids. In this work we extend GFMD in order to model both normal and tangential loading of rough solids with finite height and generic elastic properties. GFMD is then used to numerically calculate the proportionality constant κ between the area of real contact ar and nominal pressure p for the contact between a compressible linear elastic solid and a rough rigid punch. The numerically calculated value of the proportionality constant k is then extrapolated to the thermodynamic, fractal and continuum (TFC) limit. Results are then compared with that of the other analytical models
Multi-species electrochemical reaction modeling using lattice Boltzmann method: study of transport phenomena in alkaline water electrolyzer
No full textEnhancing the efficiency of industrial water electrolysis for hydrogen production is vital for the energy transition. In Alkaline Water Electrolysis (AWE), hydrogen is produced at the cathode, and the bubbles are formed when the local hydrogen concentration exceeds the solubility limit. It is important to understand the exact local conditions that result in the nucleation of bubbles in this multi-phase and reactive system. With modeling, it is possible to gain insight into the relation between various local properties, but the model needs to include all relevant physics and chemistry. Thus, this work focuses on the multi-species electrochemical transport phenomena with reaction occurring on the electrode-electrolyte interface.The electrochemical transport phenomena and the bubble nucleation are meso-scale phenomena occurring at the electrode-electrolyte interface. Lattice Boltzmann Method (LBM) is well suited for modeling meso- scale behavior but it is computationally memory expensive. Consequently, a hybrid approach combining Finite Difference Method (FDM) and LBM has been developed to simulate transport phenomena in the migration-diffusion problem with heterogeneous reaction kinetics. The Debye-Hückel theory is used as a benchmark to validate the developed model. Subsequently, the model is employed to simulate the transport phenomena occurring in the hydrogen half-cell of AWE, with a specific focus on the Hydrogen Evolution Reaction (HER) governed by the Butler-Volmer kinetics equation.The model captures the dynamic evolution of physical parameters such as electric potential, concentration of species, and fluxes within the system particularly in the Electric-Double layer (EDL). The effect of electrode potential on the distribution of species involved in the reaction are studied by performing simulations for different electrode potential. The influence of secondary fluxes on the species distributionis studied by implementing a spatially varying boundary condition to the reacting site. Finally, the formulated methodology is extended to solve a multi-phase system with species transportation occurringaround a catalyst particle.Mechanical Engineering | Energy, Flow and Process Technolog
- …
