Computational simulation of liquid-fuelled HVOF thermal spraying

Liquid-fuelled high-velocity oxygen–fuel (HVOF) thermal spraying systems are gaining more attentions due to their advantage of producing denser coatings in comparison to their gas-fuelled counterparts. The flow through a HVOF gun is characterized by a complex array of thermodynamic phenomena involving combustion, turbulence and compressible flow. Advanced computational models have been developed to gain insight to the thermochemical processes of thermal spraying, however little work has been reported for the liquid-fuelled systems. This investigation employs a commercial finite volume CFD code to simulate the flow field through the most widely used liquid-fuel HVOF gun, JP5000 (Praxair, US). By combining numerical combustion and discrete phase models the turbulent spray flame is captured and the development of supersonic gas flow is revealed. The flow field is thoroughly examined by adjusting the nozzle throat diameter and combustion chamber size. The influence of fuel droplet size on the flame shame shape and combusting gas flow is also examined.<br/

Identification of the Salivary Proteome in Children Throughout the Course of Dental Eruption

The salivary proteome is recognized as a valuable source of potential oral and systemic disease biomarkers. Major efforts in salivary research have been dedicated to identify and characterize salivary proteins present in saliva using both classical biochemical methods and proteomics approaches in adults. Despite considerable research on the salivary proteome, little attention has been given to the changes in the salivary proteome occurring in children, specifically from 0-3 years of age. Through the use of anionic PAGE, SDS PAGE, HPLC and MS/MS, salivary protein profiles in children before, during and after dental eruption were compared with edentulous adult controls. We identified substantive qualitative and quantitative differences in the salivary proteome between children and adults, suggesting a greater emphasis is warranted in the study of the changes in the salivary proteome as a function of age and dental status

Effects of liquid swine manure placement and rate on phosphorus loss with runoff water

There is an increasing concern on the use of nitrogen (N) based manure application rate for corn production and its impact on soil phosphorus (P) buildup and the potential to release P to the environment. Therefore a field study was conducted to evaluate the effects of manure application rate and method of application on soil erosion and P loss with runoff water and sediment. Simulated rainfall was applied to 24 runoff plots to study two variables in triplicate. The first variable was application rate: liquid swine manure was applied at N recommended rate and twice the rate, and inorganic liquid fertilizer with P level that matches the amount of P supplied by manure. The second variable was placement, with manure or fertilizer either surface broadcast or incorporated;Average total runoff flow volume was found to be significantly greater for the broadcast method of manure application in comparison with the incorporated treatment. Average total runoff flow volume was also found to be greater for liquid fertilizer application treatment in comparison with manure treatment. Total suspended solids (TSS) concentrations and mass losses in runoff water were significantly greater for the liquid fertilizer treatment in comparison with manure treatment;Concentrations and total losses of all P forms with runoff water were significantly greater for fertilizer treatment in comparison with manure. These losses were significantly less when manure or fertilizer was incorporated. Concentrations of all P forms were significantly greater for the higher rates of application, but similar effects on mass losses were only found for total phosphorus, particulate phosphorus, and bioavailable phosphorus (BAP). Soil test for P (STP) by agronomic and environmental tests showed that dissolved P (DP) and BAP concentrations in runoff water were best predicted by Bray 1-P or iron oxide strip-P in soil. DP and BAP total losses with runoff water were well correlated (r \u3e 0.85) with Bray 1-P, iron oxide strip-P, and water extractable P in soil

Numerical investigations of thermal spray coating processes: combustion, supersonic flow, droplet injection, and substrate impingement phenomena

The aim of this thesis is to apply CFD methods to investigate the system characteristics of high speed thermal spray coating processes in order facilitate technological development. Supersonic flow phenomena, combustion, discrete droplet and particle migration with heating, phase change and disintegration, and particle impingement phenomena at the substrate are studied. Each published set of results provide an individual understanding of the underlying physics which control different aspects of thermal spray systems.A wide range of parametric studies have been carried out for HVOF, warm spray, and cold spay systems in order to build a better understanding of process design requirements. These parameters include: nozzle cross-section shape, particle size, processing gas type, nozzle throat diameter, and combustion chamber size. Detailed descriptions of the gas phase characteristics through liquid fuelled HVOF, warm spray, and cold spray systems are built and the interrelations between the gas and powder particle phases are discussed. A further study looks in detail at the disintegration of discrete phase water droplets, providing a new insight to the mechanisms which control droplet disintegration, and serves as a fundamental reference for future developments of liquid feedstock devices.In parallel with these gas-particle-droplet simulations, the impingement of molten and semi-molten powder droplets at the substrate is investigated and the models applied simulate the impingement, spreading and solidification. The results obtained shed light on the break-up phenomena on impact and describe in detail how the solidification process varies with an increasing impact velocity. The results obtained also visually describe the freezing induced break-up phenomenon at the splat periphery

Ocular manifestations of graft-versus-host disease

AbstractAllogeneic hematopoietic stem cell transplantation (HSCT) has evolved over the past two decades to become the standard of care for hematologic and lymphoid malignancies. Major ocular complications after allogeneic HSCT have been increasing in number and severity. Graft-versus-host disease (GVHD) remains a major cause of ocular morbidity after allogeneic HSCT. The main objective of this review is to elucidate the ocular complications in patients developing GVHD following HSCT.Ocular complications secondary to GVHD are common and include dry eye syndrome, acquisition of ocular allergy from donors with allergic disorders. Eyelid changes may occur in GVHD leading to scleroderma-like changes. Patients may develop poliosis, madarosis, vitiligo, lagophthalmos, and entropion. The cornea may show filamentary keratitis, superficial punctate keratitis, corneal ulcers, and peripheral corneal melting which may lead to perforation in severe cases. Scleritis may also occur which can be anterior or posterior. Keratoconjunctivis sicca appears to be the most common presentation of GVHD. The lacrimal glands may be involved with mononuclear cell infiltration of both the major and accessory lacrimal glands and decrease in tear production.Severe dry eye syndrome in patients with GVHD may develop conjunctival scarring, keratinization, and cicatrization of the conjunctiva.Therapy of GVHD includes systemic immunosuppression and local therapy. Surgical treatment in refractory cases includes surgical intervention to improve the manifestation of GVHD of the eye. This may include tarsorrhapy, prose lenses, punctal occlusions and corneal transplantation

Granulocytic sarcoma in a patient with chronic myeloid leukaemia in complete haematological, cytogenetic and molecular remission

Granulocytic sarcoma, also known as myeloid sarcoma, is an extramedullary tumour composed of immature myeloid cells. Granulocytic sarcoma is typically found in patients with acute myeloid leukaemia, accelerated phase or blast crisis of chronic myeloid leukaemia, myelodysplastic syndrome, or as an isolated event without bone marrow involvement. We present a case of granulocytic sarcoma in a patient with chronic myeloid leukaemia in the setting of complete haematological, molecular and cytogenetic remission. Our patient was first treated with imatinib for chronic-phase chronic myeloid leukaemia. After maintaining remission for 42 months, he developed a granulocytic sarcoma in his spine. In this case report, we describe our case, along with the three other cases reported in the literature. In addition to being a rare diagnosis, this case demonstrates the importance of being vigilant in diagnosing the cause of back pain and atypical symptoms in patients with a history of leukaemia