Magneto-hydrodynamics of multi-phase flows in heterogeneous systems with large property gradients:Multi-Component multi-phase magnetohydrodynamics

The complex interplay between thermal, hydrodynamic, and electromagnetic, forces governs the evolution of multi-phase systems in high technology applications, such as advanced manufacturing and fusion power plant operation. In this work, a new formulation of the time dependent magnetic induction equation is fully coupled to a set of conservation laws for multi-phase fluid flow, energy transport and chemical species transport that describes melting and solidification state transitions. A finite-volume discretisation of the resulting system of equations is performed, where a novel projection method is formulated to ensure that the magnetic field remains divergence free. The proposed framework is validated by accurately replicating a Hartmann flow profile. Further validation is performed through correctly predicting the experimentally observed trajectory of Argon bubbles rising in a liquid metal under varying applied magnetic fields. Finally, the applicability of the framework to technologically relevant processes is illustrated through the simulation of an electrical arc welding process between dissimilar metals. The proposed framework addresses an urgent need for numerical methods to understand the evolution of multi-phase systems with large electromagnetic property contrast

Modelling dynamic precipitation in pre-aged aluminium alloys under warm forming conditions

This work presents a model for deformation enhanced precipitate growth and coarsening kinetics in pre-aged 7xxx aluminium alloys under warm forming conditions (100 to 200 °C). A multi-class Kampmann–Wagner framework is used to describe the evolution of precipitate size distribution, where the effect of deformation is incorporated through enhanced solute diffusivity resulting from deformation induced excess vacancies. A classical phenomenological model is used to describe the accumulation of excess vacancies. The model is validated with experimental warm deformation data from the literature, and applied to investigate a wide range of deformation conditions to predict the effect of strain, strain rate and temperature on precipitate growth and coarsening kinetics. It is demonstrated that the interaction of solute supersaturation and excess vacancy concentration can lead to complex non-monotonic precipitate growth rate variation for certain regimes of strain rate and temperature

Delayed Replantation of Avulsed Incisor with Prolonged Extraoral Dry Storage

Trauma to the anterior teeth mainly affects children and adolescents. Tooth avulsion has become a common dental injury, that can occur at any age with maxillary anteriors being commonly affected. It affects the esthetics and psychological well being of both the child and the parent. Management of tooth avulsion in the permanent dentition often presents a challenge to the dental professional. Definitive treatment planning and consultation with specialists is seldom possible at the time of emergency treatment. Replantation of the avulsed tooth is an immediate procedure, which can restore the esthetics, function and create positive impact on patient if carried out under ideal conditions. This article describes the management of a patient with an avulsed maxillary permanent central incisor, that had been stored in unfavorable conditions for about 48 hours. Adequate space maintenance, esthetics and functional requirements of the patient were totally met till a long-term treatment is planned, when the patient finishes his pubertal growth.&nbsp

Interactions between plastic deformation and precipitation in Aluminium alloys: A crystal plasticity model

This work presents a crystal plasticity model for dynamic precipitation in aluminium alloys. It takes into account both the influence of an evolving precipitate distribution on the critical stress for dislocation glide, and the accelerating effect of deformation on precipitation kinetics. The effect of precipitates on deformation behaviour is integrated into the crystal plasticity constitutive law. The effect of deformation on precipitation kinetics is modelled spatio-temporally using a multi-class precipitation kinetic model (KWN) incorporating the effect of deformation through accelerated solute diffusion caused by the production of excess vacancies. The model is applied to growth and coarsening of shearable precipitates in pre-aged AA7075 alloy under deformation at 150°C, which corresponds to an industrially relevant production. This paper first explores the influence of dynamic precipitation on the tensile behaviour, showing that dynamic precipitation might be responsible for a gain in uniform elongation and tensile stress of respectively 2% strain and 50 MPa for the case at hand. The influence of dynamic precipitation on the development of plastic strain heterogeneities is discussed. The model demonstrates how spatial heterogeneities in precipitate distribution may develop during deformation, and how these heterogeneities correlate with the development of strain heterogeneities. The precipitate distributions obtained under static or dynamic ageing are predicted and compared with each other, and the influence of texture is discussed

Computational study of the geometrical influence of grain topography on short crack propagation in AA7XXX series alloys

Intergranular Environmentally-Assisted Cracking (EAC) has recently been reported to be an issue of concern innew-generation 7000 series aluminium alloys, such as AA7085, when exposed to humid air. The cracking processoccurs in a highly brittle manner almost exclusively along grain boundaries (GB’s) and has been attributed tohydrogen embrittlement, probably by GB decohesion within the stress field at the crack tip. Currently, how thehighly heterogeneous grain structures found in these partially recrystallized materials impact the growth behaviourof microstructurally short cracks is poorly understood. In particular, there is expected to be a high sensitivity tothe grain structure in the transition from initiation to sustained propagation, where the local mechanical drivingforce is very sensitive to the crack path. Volume Elements, VE's, with synthetic grain structures have beengenerated from real microstructure and texture data, so that the effects of important grain structure variables canbe explored in crystal-plasticity simulations, to understand the extent to which typical grain-structural featuresaffect the driving force for short-crack growth. Specifically, by considering the effect of different uncrystallisedgrain aspect ratios and embedding recrystallised grains in the model, the strain energy release rate has beencalculated as a function of crack path. This has revealed large reductions and fluctuations in the driving force forshort cracks in relation to the local grain structure encountered by the crack tip, which have been estimated by themodel

Botox: Buy Me Beauty!

‘Beauty lies in the eyes of the beholder’. Beauty has been admired since time immemorial not only by the medical personals but also by the general masses. Beauty undoubtedly has a strong influence on human life. Orthodontists have a special interest in facial beauty. One of the most socially significant of human behaviors is expression of emotions on the face with smile being the most important of those emotions. The display of excessive gingival tissue in the maxilla upon smiling has been called a ‘gummy smile’, a condition some consider esthetically displeasing. Some people with excessive gingival display are self-conscious or embarrassed about it, and some are psychologically affected. There are a number of different treatment methods described in the literature for the treatment of gummy smile. These includes both surgical and nonsurgical options, including Le Fort I osteotomy, crown lengthening procedure, maxillary incisor intrusion, self-curing silicone implant injected at the anterior nasal spine and finally myectomy and partial resection of the levator labii superioris or muscle repositioning. Some patients do not wish to go through the long presurgical orthodontic treatment in preparation for a Le Fort I osteotomy while others wish to avoid the possible complications surrounding surgery, such as postoperative pain, swelling and infection, permanent or temporary nerve damage and root damage during osteotomy. A nonsurgical alternative for reducing excessive gingival display caused by muscle hyperfunction would be advantageous. Botulinum toxin has been under clinical investigation since the late 1970s for the treatment of several conditions associated with excessive muscle contraction or pain. The aim of this article is to give an overview about the science of Botox and its various uses

Combination syndrome: An update

Destructive changes in the hard and soft tissues have been reported in patients with maxillary complete denture opposed by natural anterior teeth and a bilateral distal extension removable partial denture. The characteristic features of these changes include loss of bone from anterior portion of the maxillary ridge, overgrowth of the tuberosities, papillary hyperplasia of hard palatal mucosa, extrusion of mandibular anterior teeth and loss of alveolar bone and ridge height beneath the mandibular removable partial denture bases, which is termed as combination syndrome as described by Kelly. This article reviews about sequelae of combination syndrome and recent treatment modalities in treating combination syndrome