Chemical Engineering Commons^™

Biodegradable Magnesium Alloys For Orthopaedic Applications: A Review On Corrosion, Biocompatibility And Surface Modifications., Sankalp Agarwal, James Curtin, Brendan Duffy, Swarna Jaiswal

Articles

Magnesium (Mg) and its alloys have been extensively explored as potential biodegradable implant materials for orthopaedic applications (e.g. Fracture fixation). However, the rapid corrosion of Mg based alloys in physiological conditions has delayed their introduction for therapeutic applications to date. The present review focuses on corrosion, biocompatibility and surface modifications of biodegradable Mg alloys for orthopaedic applications. Initially, the corrosion behaviour of Mg alloys and the effect of alloying elements on corrosion and biocompatibility is discussed. Furthermore, the influence of polymeric deposit coatings, namely sol-gel, synthetic aliphatic polyesters and natural polymers on corrosion and biological performance of Mg and its …

Experimental And Modeling Studies In Membrane Distillation, Lin Li

Dissertations

A variety of microporous hydrophobic flat sheet membranes of polyvinylidene fluoride (PVDF) and expanded-polytetrafluoroethylene (e-PTFE) are studied to evaluate the influence of membrane properties on their performance in desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) processes. The membrane thickness is varied between 23 μm to 125 μm; the pore size is varied from 0.05 μm to 0.45 μm. The porosity is generally high in the range of 0.7 - 0.8. DCMD experiments are performed over a hot brine temperature range of 65 °C to 85 °C and distillate temperature at 25 °C for various brine …

Dissolution Kinetics Of Model Api In Molten Polymer Excipients During Batch Processing, Shen Ji

Theses

In the pharmaceutical industrial application field, hot-melt extrusion (HME) has been recently introduced to develop new solid dosage forms and products. By dissolving the poorly–soluble active pharmaceutical ingredients (API) into water-soluble polymers, the bioavailability of the Class II (with low solubility and high permeability in water) API in Biopharmaceutical Classification System (BCS) could be significantly improved in the body. For readily water-soluble API, HME provides a new approach to produce a controlled release drug system. Hence, pharmaceutical HME is a promising processing method in the pharmaceutical industry.

However, HME has not been widely applied into the pharmaceutical industry. The thermal …

Preparation, Ignition And Combustion Of Reactive Metal-Sulfur Nanocomposites, Ziyue Zhong

Theses

Mechanical milling is applied to synthesize reactive metal-sulfur nanocomposites. Specifically, magnesium-sulfur, aluminum-sulfur and zirconium-sulfur nanocomposite powders are prepared. Each powder particle contained homogeneously mixed sulfur and respective metal. These materials are expected to be stable in room air. They are also expected to release sulfur upon ignition; the released sulfur may serve as a biocidal agent. The ignition temperatures of the three prepared sulfur-bearing materials fall in a range of 750 - 1000 K. All prepared materials are successfully ignited in electrostatic discharge experiment as well as in a constant volume explosion experiment. The most sensitive material to spark ignition …

Development And Analysis Of Aluminum-Ptfe Reactive Composite Material, Siva Kumar Valluri

Theses

The shortcomings of micron sized aluminum due to the oxide barrier and two phase loses pose a hindrance for its efficient use as a fuel. In this study a fluoropolymer; Teflon’s inclusion in micron sized -325 mesh aluminum is suggested as a replacement to aluminum. Aluminum Teflon based energetic material see great potential for use in pyrotechnics, propellants and even explosives. A composite with composition Al-PTFE (90-10 wt. %) is prepared through Cryomilling and is shown to be a better method of preparation as compared to room temperature milling. The prepared materials are studied to identify best conditions. The analysis …

Raman Spectroscopic Analysis Of Fingernail Clippings Can Help Differentiate Between Postmenopausal Women Who Have And Have Not Suffered A Fracture, James R. Beattie, Niamh M. Cummins, Clare Caraher, Olive M. O'Driscoll, Aruna T. Bansal, Richard Eastell, Stuart H. Ralston, Michael D. Stone, Gill Pearson, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Raman spectroscopy was applied to nail clippings from 633 postmenopausal British and Irish women, from six clinical sites, of whom 42% had experienced a fragility fracture. The objective was to build a prediction algorithm for fracture using data from four sites (known as the calibration set) and test its performance using data from the other two sites (known as the validation set). Results from the validation set showed that a novel algorithm, combining spectroscopy data with clinical data, provided area under the curve (AUC) of 74% compared to an AUC of 60% from a reduced QFracture score (a clinically accepted …

Oxidation Kinetics Of Metallic Powders, Hongqi Nie

Dissertations

Aluminum and magnesium are widely used in pyrotechnic formulations and other energetic materials; they are also common components of reactive alloys, e.g., Al-Mg and B-Mg, and others, which are potential fuels for explosives and propellants. Reaction mechanisms and oxidation kinetics of aluminum, magnesium and Al-Mg alloy powders in different oxidizing environments are investigated using thermo-analytical measurements. New methods of data processing are developed, relying on measured particle size distributions of the reactive spherical powders. It became possible to identify the reaction interface location for many heterogeneous metal oxidation processes; for several reactions, detailed kinetic descriptions are obtained.

For aluminum powders, …

Custom Engineered Nanomaterials For Energetics And Energy Applications, Ani Abraham

Dissertations

Recent interest in reactive material has shifted to more custom formulations targeting specific applications. In this work, preparation and characterization of nanomaterials used for several energetics and energy applications are addressed.

The main challenge of this effort is to design and prepare nanomaterials which have significant improvements associated with combustion dynamics, reaction rates, sensitivity, biocidal effectiveness, moisture stability, and are environmentally safer over the existing energetics. Nanomaterials that are used to defeat stockpiles of chemical and biological weapons, modify ionosphere properties for transmission of optical and radio signals, and for energy storage are prepared under room or cryogenic temperatures via …

Nano-Photonic Waveguides For Chemical And Biomedical Sensing, Surya Venkatasekhar Cheemalapati

USF Tampa Graduate Theses and Dissertations

In this dissertation, advances in the fields of Photonics, and Plasmonics, and specifically, single cell analysis and waveguide sensing will be addressed. The first part of the dissertation is on Finite Difference Time Domain (FDTD) optimization and experimental demonstration of a nano-scale instrument that allows sensing at the cellular and subcellular levels. A new design of plasmonic coupler into a nanoscale waveguide is proposed and optimized using FDTD simulations. Following this, a subcellular nanoendoscope that can locally excite fluorescence in labelled cell organelles and collect the emitted fluorescent light for detailed spectrum analysis is fabricated and tested. The nanoendoscope has …

Force On A Large Sphere Immersed In An Expanded Water-Fluidized Bed Over A Wide Range Of Voidage Values, Alberto Di Renzo, Nicola Grassano, Francesco P. Di Maio

Fluidization XV

The presence of large objects immersed in a fluidized bed has been long studied in order to verify to what extent can the analogy with a buoyant body in a liquid represent the object-to-suspension interaction (1). One of the most useful information resulting from such study is the effective drag force exerted on the object and how it is related to the suspension properties, particularly with respect to the expansion degree. Implications are found also in the formulation of drag force expressions for homogeneous polydisperse systems.

In the present work an experimental series of tests has been conducted on a …

Applications Of Tribology And Fracture Mechanics To Determine Wear And Impact Attrition Of Particulate Solids In Cfb Systems, Ronald W. Breault, Samuel C. Bayham, Esmail R. Monazam

Fluidization XV

In recent years, much attention has been focused on the development of novel technologies for carbon capture and chemicals production that utilize a circulating fluidized bed configuration; examples include chemical looping combustion and circulation of temperature swing adsorbents in a CFB configuration for CO2 capture. A major uncertainty in determining the economic feasibility of these technologies is the required solids makeup rate, which, among other factors, is due to impact and wear attrition at various locations, including standpipes, cyclones, and the gas jets in fluid beds. While correlations have been developed that estimate the attrition rates at these areas, these …

Experimental Validation Of Cfd Hydrodynamic Models For Catalytic Fast Pyrolysis (Cfp), Bruce D Adkins, Travis Dudley, Neeti Kapur, Peter Blaser, James Parker

Fluidization XV

Catalytic Fast Pyrolysis (CFP) is a means of producing renewable fuels and chemicals from lignocellulosic biomass. KiOR, a world leader in this area, has developed a CFP technology along the lines of the FCC process.

In early 2015, KiOR engaged with CPFD Software to develop a new, parallel path for developing and optimizing its CFP technology. Emphasis was placed on hydrodynamics predictions, since that is one key area where KiOR’s CFP differs significantly from FCC. The KiOR-CPFD team reduced the hydrodynamics validation problem to four key milestones. Each milestone needs independent experimental validation, and must build on the previous ones: …

Combustion Of Lignin-Rich Residues With Coal In A Pilot-Scale Bubbling Fluidized Bed Reactor, Roberto Solimene, Riccardo Chirone, Antonio Cammarota, Nicola Rossi, Paolo Leoni, Piero Salatino

Fluidization XV

The deployment and the exploitation of bioethanol as automotive fuel became more and more relevant to reduce the emissions of greenhouse gases and to limit the dependence on countries supplying fossil fuels. However, the production of second-generation bioethanol, i.e. using lignocellulosic biomass or scraps of agricultural crops as feedstock, generates a waste stream consisting of lignin-rich residues whose fate has to be found (1-2). This work aims at investigating the combustion of lignin-rich residues (in the following simply called lignin), coming from a second-generation bioethanol production plant, with coal in a pilot-scale bubbling fluidized bed combustor (FBC). The pilot-scale 200kW …

Micro/Meso Simulations Of A Fluidized Bed With Heat Transfer, Florian Euzenat, Anthony Wachs, Abdelkader Hammouti, Pascal Fede, Eric Climent

Fluidization XV

Particulate flows encountered in fluidized beds are frequently used in industrial applications (refining, energy, chemicals/petrochemicals, pharmaceutics). The wide range of spatial scales and interactions between the phases in such systems yields a complex flow often coupled with mass and/or heat transfer. These transfer have been widely investigated in the past in an experimental and numerical manners for dilute (1, 2) and dense suspensions (3, 4).

Multi-scale modeling is a numerical approach developed to understand these phenomena from the particle scale (microscale) to process unit (macroscale). An intermediate scale (mesoscale) ranging from 10⁴ to 10⁸ particles is also introduced. …

Cfd-Dem Simulation Of Nanoparticle Agglomerates Fluidization With A Micro- Jet, Daoyin Liu, Berend G. M. Van Wachem, J. Ruud Van Ommen, Robert F. Mudde, Xiaoping Chen

Fluidization XV

Nanoparticles can be fluidized as agglomerates, but for some materials this is cumbersome due to the cohesive nature. Micro-jets are shown to be effective for improving the fluidization in such cases (1). In this study, the mechanisms of micro-jet assistance are investigated by using an adhesive CFD-DEM (Computational Fluid Dynamics – Discrete Element Modelling) model. In previous studies, the complex agglomerates found in a fluidized bed are treated as the discrete elements (2). Here we use the simple agglomerates as the discrete elements, which are the building blocks of the larger complex agglomerates. The collision of the simple agglomerates are …

Segregation Of Equal-Sized Particles Of Different Densities In A Vertically Vibrated Fluidized Bed, E. Cano-Pleite, A. Acosta-Iborra, F. Hernández-Jiménez, T. Tsuji, C. R. Müller

Fluidization XV

Many operations in the chemical and energy-conversion industries rely on the fluidization of heterogeneous materials. During fluidization, particles of different densities can segregate, even if they are of the same size. Segregation is typically an undesired phenomenon, especially in fluidized bed reactors (1). Thus, an understanding of segregation on a fundamental level is paramount to identify effective measures to control it. One approach to control segregation could be the vibration of the bed vessel. However, there is very little literature available concerning the effect of vibration on density-induced segregation dynamics (2).

Thus, this work studies the influence of vibration on …

Reversal Of Gulf Stream Circulation In A Vertically Vibrated Triangular Fluidized Bed, E. Cano-Pleite, A. Acosta-Iborra, F. Hernández-Jiménez, C. R. Müller

Fluidization XV

Vibrated fluidized beds are a process intensification technique consisting in introducing vibratory kinetic energy in a fluidized bed (1). In this work we assess experimentally the effect of vibration on the gulf-stream circulation pattern of particles in a fluidized bed that is of triangular shape. The bed has 0.206 m span and 0.01 m thickness. The base of the bed is composed of two inclined walls, each one forming an angle of 45º with the horizontal. Air was injected through the inclined bed walls to fluidize the bed (see Figure 1a). This gas injection, together with vibration, can make the …

Experimental Study Of Solid Mixing Mechanism In A 2d Fluidized Bed, J. Sánchez-Prieto, A. Soria-Verdugo, L.M. García-Gutiérrez, F. Hernández-Jiménez, F. Suárez-Gómez

Fluidization XV

The main mechanism of solids mixing in bubbling fluidized beds is well understood. When a bubble rises through the bed, it carries a wake of particles to the bed surface. A downflow of solids exists in the region surrounding the rising bubbles, resulting on an overall convective circulation of particles in the axial direction (1).

In this work, a new method to characterize solids mixing in a 2D fluidized bed is developed. This mixing index is able to macroscopically characterize the rate of mixing in a fluidized bed by means of DIA. The mixing index is analogous to the Lacey’s …

Microscopic Modelling Of Capillary Liquid Bridge Force And Volume Repartition For Dem Simulations Of Polydisperse Systems, Alberto Di Renzo, Andrea Lorenti, Francesco P. Di Maio

Fluidization XV

Many fluidization processes like granulation, agglomeration, encapsulation or coating exhibit conditions where liquid bridges form between particles (1), resulting in strong particle-particle interactions at the microscopic scale. DEM and DEM-CFD simulations are able to show how the particle-scale phenomena determine the overall behavior of a wet particulate material in industrial systems.

Description of the capillary interaction between spherical particles in the pendular regime (i.e. with liquid bridges forming on a one-to-one basis) has been long studied and characterized, particularly in the case of spheres of the same size. When polydisperse systems are considered, the formation, interaction force and rupture of …

Recirculating Fluidized Bed Reactor For Chemical-Looping, Raman Sharma, Mines Paristech, Arnaud Delebarre, Babu Alappat

Fluidization XV

Chemical-Looping Combustion (CLC) is an oxy-combustion CO₂ capture technique. CLC involves metal oxides to split the combustion in oxidation and reduction cycles. A wide variety of reactors, single as well as interconnected, have been tested for CLC. These reactor configurations have some operational and process difficulties associated with them. A single Recirculating Fluidized Beds (RCFB) reactor configuration is proposed here for CLC with a feeling that it can overcome some of these problems. RCFB is a spouted fluidized bed with a central riser tube and the outer tube is known as downcomer. A cold model of RCFB reactor was …