Exam 1 Review
Exam 1 Review BE305
Popular in Biomaterials and mechanics
verified elite notetaker
verified elite notetaker
verified elite notetaker
PSC 204- Dr. Chyzh
verified elite notetaker
verified elite notetaker
Popular in Biomedical Sciences
This 12 page Study Guide was uploaded by Notetaker Notetaker on Tuesday February 17, 2015. The Study Guide belongs to BE305 at University at Buffalo taught by Professor Zhao in Fall. Since its upload, it has received 171 views. For similar materials see Biomaterials and mechanics in Biomedical Sciences at University at Buffalo.
Reviews for Exam 1 Review
Eugh...this class is soo hard! I'm so glad that you'll be posting notes this semester.
-Elfrieda Tromp DDS
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/17/15
General Properties 0 Crystalline Materials Periodic 3D arrays 0 NonCrystalline Materials No Periodic Packing 0 Amorphous Have no organizational structure to packing 0 Atom Packing Dense regular packing Non dense irregular packing 0 Densities Metals have close packing and a large atomic mass Ceramics have less dense packing and lighter elements Polymers have poor packing and even lighter elements 0 Thermal Properties Metals and other crystalline structures typically have a set melting point Ceramics if amorphous have no fixed melting point Polymers have a variety of different properties which can exist dependent upon the temperature Metals 0 Used in load bearing applications 0 Can be an alloy of two or more metals Alloys allow for better corrosion resistance and strength 0 Applications Orthopedics oral and maxillofacial and cardiovascular 0 Common metals Stainless Steel Cobalt Chromium Molybdenum Titanium 0 Crystalline in structure with a periodic order Simplest unit is the unit cell 0 Unit cells repeat nicely and this allows XRay diffraction to be used to analyze the structure of the material Common crystalline structures gt Body Centered Cubic gt Face Centered Cubic gt Hexagonal Close Packed Atomic Packing Fraction APF 2 Volume of the A toms E the Ifmt Cell Total Volume of the Umt Cell 0 Coordination Number number of atoms which share a corner junction 0 Metallic Defects in the lattice structure Point Defect gt SelfInterstitial gt Vacancy Impurities Atom size electronegativity and valiancy must be similar gt Interstitial impurity atom gt Substitutional Impurity Atom Metal Alloys 0 Impurities are added to provide corrosion resistance andor strength Stainless steel is a great example 0 To create an alloy it will need to be remelted alloyed and then retested to verify the properties of the new material 0 Alloy oxides are traditionally more stable allowing for surface pacification to occur reducing the amount of biomaterial body interactions Ceramics 0 Nonmetallic solid which is produced by heating and subsequent cooling 0 Held together by ionic andor covalent bonds 0 Can be crystalline partially crystalline or amorphous 0 Bioceramics Bioinert Bioactive Biodegradable or soluble 0 Bone is a ceramic which is naturally found in nature 0 Ion size is critical Cations prefer to have the maximum amount of anion contact Stable ceramics have cations that are as large or larger than anions Unstable ceramics have cations which are smaller than the present anions 0 Impurities must maintain electronegativity Schottky Defect gt Anion and cation are missing Frenkel Defect gt Cation has moved locations Polymers 0 Formation of polymers Addition Reactions gt Monomer is added onto the end of the growing polymer chain Condensation Reactions gt Two different monomers are added together and condense together forming a polymer which leaves a byproduct The continual reaction needs alternating forms of the two precursor monomers 0 Techniques for Forming Polymers Bulk Polymerization gt Bulk monomer is added and the reaction is allowed to proceed The polymer is extracted chemically Solution Polymerization gt Monomers are soluble in solution while the polymer is typically not soluble in solution Suspension Polymerization gt Insoluble monomer sits on the surface of the solution where polymerization occurs in congealed groups of monomer Emulsion Polymerization gt Droplets of the polymermonomer are stabilized with an emulsifying agent 0 Molecular Structure Homopolymer Random Alternating Block Graft 0 Physical Structure Linear Branched Crosslinked 3D Network 0 Thermal Response Thermoplastic gt Heat allows the shape to be changed Cooling and reheating allows the shape to again be changed Thermosetting gt Heat allows the shape to be changed however once cooled the object will be set in the shape it cooled in 0 Thermal Properties Glassy Polymers gt Temperature is below the glass transition temperature gt Hard and brittle Rubbery or Leathery Polymers gt Temperature is between the melting point and the glass transition point gt Deform plastically and elastically at this point Liquid Polymers gt Temperature is greater than that of the melting point gt Bonds between chains are very weak allowing them to slide past one another with little effort 0 Tacticity Refers to the configuration of the side groups on the polymer Isotactic the specified group is found on the same side of the polymer Syndiotactic the specified group is found on alternating sides Atactic the specified group is randomly placed on the polymer 0 Degradation useful for drug release Mixing of the polymer and the drug allows for release from the polymer surface Preencapsulating the drug allows for release once the polymer has degraded to a certain extent Can also be used for cell release such as providing a scaffold which cells can grow on Biostable gt 810 years Biodegradable gt Less than one year Biostable and Bioeliminable gt Hours or Days 0 Morphology Dependent upon structure and molecular interactions gt Chemical structure and molecular weight gt Physical Structure Polymer branching and side chains gt Molecular Structure Regularity of the units in copolymers gt Physical interactions gt Tacticity see below Amorphous Crystalline Semicrystalline Hydrogels 0 Insoluble network of polymer chains which swell 0 Physical properties of the hydrogel are classified by Covalent Junctions gt Chemical reaction to induct crosslinking Physical noncovalent junctions gt Hydrophobic interactions van der Waals forces gt Hydrogen Bonding gt Ionic Interactions gt Protein Interactions gt Temperature Mediation These two properties can be mixed to achieve a variety of different factors which affect the swelling of a hydrogel 0 The amount of swelling which occurs depends on two factors Equilibrium is achieved when these forces are equal to each other Swelling force gt The effect of the water entering the hydrogel and forcing it apart Retraction force gt The effect of the polymer chains resisting the water in ux 0 The amount which the hydrogel swells affects the useful properties of the hydrogel Solute Diffusion through the gel gt Can affect drug release Surface properties Optical properties Mechanical Properties Degradation of Biomaterials 0 Biodegradation Degradation due to biological activity 0 Bioerosion Degradation due to physical andor chemical activity in the biological environment 0 Bioresorption and Bioabsorption Consumption of degradation products by biological activity 0 Unwanted Degradation Metallic implants corroding in a biological environment 0 Wanted Degradation Design of the biomaterial to degrade to help drug delivery or tissue engineering Degradation of Metals 0 Electrochemical reaction at the surface of the metallic implant REDOX reaction gt If the free energy of oxidation is less than zero it Will occur spontaneously dependent upon the separation of the ions Measurement of the reduction potential of a metal to be reduced gt More negative reduction potentials Will be more reactive gt Low potentials are said to be active While high potentials are said to be noble gt Nernst Equation is used Pourbaix Diagram illustrates the correlation between potential and pH 0 Processing Parameters Crevice Corrosion gt Occurs in spaces Where access to uid in an environment is limited Pitting Corrosion gt Localized Corrosion Which leads to the creation of small holes in the metal Intergranular Corrosion gt Grain boundaries of crystals are more susceptible to corrosion than their insides 0 Mechanical Environment Stress Corrosion gt Metal under tension can be corroded Fatigue Corrosion gt Metal is under continuous bending or exing 0 Alleviation of degradation on metals Correct electrochemical properties gt Account for the nonideal environment of the body including the presence of hydrogen gas Metallic oxides Will passivates the surface Degradation of Ceramics 0 Developed from different forms of calcium phosphates Which are naturally found in the body 0 Do not show corrosion 0 Interact though chemical or physical interactions 0 Bioinert Ceramics Alumina Morphological Fixation gt Dense and nonporous gt Cemented or pressfit into the location of the defect Porous Fixation gt Porous gt Allows mechanical tissue ingrowths in place of chemical cement 0 Bioactive Ceramics Glass Ceramics Bioactive Fixation gt Dense nonporous surface directly bonds to surfacetissue though bond formation gt Must stimulate the healing process gt Rate of change in the surface of the material is the sum of the rate of disappearance and rate of formation 0 Bioresorbable Ceramics Calcium Phosphate Biodegradation gt Due to cellular or chemical reactions gt No long term consequences V Stress shielding loosening or stability Calcium Phosphate gt 7 Different forms based on various chemical properties gt Degradation is caused by V pH of the environment V Physical disintegration V Biological factors macrophages or other responses gt Degradation is controlled by V Surface area V Grain size and crystal structure V Substitutions in the material Degradation of Polymers O Biostable Long term Bioinert O Biodegradable Temporary Avoidance of in ammation and long term complications 0 Degradation Methods Primary Bonds gt Using water or a highly reactive species to break primary bonds Secondary Bonds gt Swelling and dissolution of the secondary bonds via a solvent 0 Hydrolytic Degradation Scission of chemical groups using water as a reactant Surface Erosion Hydrolysis gt Exterior surface of the polymer is degraded gt Linear loss of material Bulk Erosion Hydrolysis gt Polymer is degraded uniformly interiorly and exteriorly gt Nonlinear loss of material Balance between surface and bulk hydrolysis depends on water diffusion and chain cleavage rates Dependent upon gt Hydrophobicity Crystal Structure Molecular Weight Degree of Crosslinking Steric Effect gt Surface and Bulk Morphology 0 Oxidative Degradation Abstraction of a hydrogen yielding an ion or radical for direct oxidation gt Superoxide anion and hydrogen peroxide from neutrophils and macrophages gt Catalyzed by metal ions llll 0 Enzymatic Degradation Natural and synthetic polymers can be degraded this way Quicker than hydrolysis Degradation can be localized to the location where the enzyme is located 0 Measuring Degradation Rates Mass change with respect to time Molecular weight change Mechanical and optical properties of the polymer Surface and bulk morphology Biomaterial Processing Metal Processing 0 Raw metal ore is refined to the needed metal type 0 Metal ore is processed into a stock shape Casting gt Liquid metal is poured into a mold and allowed to solidify Forging gt Shaping by plastic deformation by compressive forces Drawing gt Using tensile force to stretch the metal into a desired shape 0 Heat treatment Releases stress found in the metal Obtain special microstructures Improved machinability formability and reduction in ductility 0 Processing into a metal device via the fabrication process Investment gt Creating a wax structure incasing it in a ceramic case and then pouring the liquid metal into the ceramic case allowing the wax to melt CAD Design gt Machining to specific specifications and tolerances Hot Isostatic Pressing gt Reduces porosity of the metal and improves the mechanical and workability properties 0 Surface Preparation Porous Coatings Plasma Treatment Nitriding 0 End Product Finalization Cleaning and passivating Packing and shipping Ceramic Processing 0 Glass Forming Heating of the ceramic between the working and softening temperature in a mold Air is then injected and the ceramic takes the shape of the mold which it is placed into 0 Casting and Firing Ceramic particles which are mixed with water and organic binders are placed in a mold Upon fully drying the material is fired at a high temperature 0 Powder Processing Ceramic particles which are mixed with water and organic binders are sintered at a high temperature to give shape Polymer Processing 0 Molded Products screws plates and other orthopedic applications Compression Molding gt Compressive force is used to shape the plastic Injection Molding gt The plastic is injected into the mold via high pressure 0 Fibrous Manufacturing Fiber Extrusion gt Polymer chips or beads are heated and spun into a larger fiber by sequentially larger rolls Electrospinning gt A syringe injects thin polymer strands onto a charged plate effectively creating a random distribution of polymer frequency on the charged plate 0 Polymer Foam Porous Scaffold is created by solvent casting and particulate leaching 0 Phase separation Emulsion Process gt Two immiscible phases With surfactant Biomaterial Sterilization 0 Critical for minimization of a host response 0 Effectiveness is measured via the Sterility Assurance Level Steam Treatment Denatures cell proteins gt Simple cheap nontoxic gt Can soften polymers and cause degradation of hydrolytically cleavable biomaterials Ethylene Oxide Sterilization through alkylation Substitution of hydrogen atoms in key molecules disabling functionality gt Low temperature effective gt Toxic expensive and chemically alters materials Radiation Ionization of key molecules in the cell disrupting the chemical bonds gt Rapid effective gt Expensive shielding needed polymer can degrade Material Characterization Spectroscopy 0 Related to the amount of energy Which is absorbed Chromatography 0 Separation based on the chemical properties of the material XRay Diffraction 0 Constructive and Destructive interference are re ected 0 Useful in crystalline materials to tell crystalline structure based on patterns seen Ultraviolet and Visible Light Spectroscopy 0 Electrons are excited and jump to different energy levels 0 Absorption occurs at various wavelengths Which depend on chemical structure IR Spectroscopy 0 Infrared light incident on the molecule causes the bonds of the molecule to Vibrate or move at a certain frequency Which is measurable dependent upon the type of bond Nuclear Magnetic Resonance 0 High energy magnetic fields cause the hydrogen atom electrons to change circulation patterns Which is measurable 0 Dependent upon Where the hydrogen is located in the molecule Will change the amount of energy which is needed to cause the electrons to change patterns Mass Spectrometry 0 High energy electron collides With the molecule causing it to fragment The positive fragments are then measured by the machine 0 Molecular ion is the total mass of the molecule minus an electron negligible weight 0 mz is the mass to charge ratio Size Exclusion Chromatography 0 Column With a porous packing material 0 Molecules Which are bigger Will not enter the pores and Will therefore take a smaller amount of time to pass though the column 0 Smaller molecules Will become trapped in the porous material and take a longer amount of time to pass through the column
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'