Tenta flashcards inte 2023

Question 1

What is charactererizing soluble ceramics?

Answer 1

They bonds are destroyed in aqueous medium. Dissolve speed is increased by high surface to mas ratio, low crystallinity, small grain size

Question 2

Explain SIMS

Answer 2

Uses ions to fire at a sample. The molecules/ions scatter from the surface and it can be mapped, like billiard. May be destructive for organic samples.

Question 3

Explain the three types of cells that a biomaterial may interact with and the possible clinical outcomes thereof

Answer 3

Target cells that theraphy is aimed at. Required interaction–> good outcome

Defensive cells from the innate and adaptive immnue system. No effect –> god outcome

Interfering cells “getting in the way”. No effect –> good outcome

Question 4

What is an auxetic material?

Answer 4

Material with negative poisson value

Question 5

ECM constituents

Answer 5

Fibrillar proteins (collagens, elastin)

Amorphous matrix (glycosaminoglycans, proteoglycans and hyaluronan)

Adhesive molecules (fibronectin, laminin)

Question 6

Two statements true for biomaterial surfaces, three properties that can be measured

Answer 6

Surfaces have unique reactivity, different from bulk, readily contaminates

Smoothness, chemistry, composition

Question 6

Four strategies of strengthening metals

Answer 6

1. Solid solution strengthening
2. Precipitation strengthening
3. Work hardening
4. Grain size strengthening

Question 7

Why does “solid solution strengthening” work and how does it strengthen the material?

Answer 7

Impurity atoms distort the lattice and generate stress which can produce a barrier to dislocation motion

Question 8

One example of a thermoplsatic, thermoset, elstomere

Answer 8

Polyester, epoxies, Silicones

Question 9

Three fundamental molecular properties of polymers. How can these be altered and what would happen?

Answer 9

Chain stiffness, chain polarity, chain architecture
1. Longer chain –> increased MW –> more rigid

2. Replacing side groups –> Lesser perfecion of molecular packing –> decreased Tm and crystallinity
3. Creating copolymers –> i.e substitute carbin backbone with more rigid structures –> stiffer chain

Question 10

Why is the degree of a hydrogel swelling important?

Answer 10

1. Affects the solute diffusion coefficient through the gel which in turn affects drug delivery, oxygen diffusion,
2. Surface properties change
3. Optical properties change
4. Mechanical properties change

Question 11

How to quantify swelling of a hydrogel?

Answer 11

Ratio of the sample volume or weight in the swollen state to the volume or weight of the dry state

Question 12

Illustrate the three fabrication methods for ceramics in a diagram showing defect frequency vs defect size

Answer 12

Powder - Tall, narrow

Shaping - Medium tall, medium narrow

Surface - Flat, wide

Question 13

Give 2 examples of important features that dictates which type of erosion that takes place

Answer 13

Hydrophobicity

“Critikal thickness”, could prevent surface erosion

Question 14

Describe what is meant by “metal reactivity”

Answer 14

How quickly a metal reacts within a aqueos solution

Question 15

How can you improve the strength of a 1. metal, 2. ceramic, 3. polymer. One strengthening method for each.

Answer 15

1. solid solution strengthening - Impurity atoms distort the lattice and generate stress which can produce a barrier to dislocation motion
2. Powder fabrication –> Reduce size of defects
3. Increase chain stiffness by making it longer or increasing cross linking

Question 16

Main degradation mechanisms of a 1. metal 2. ceramic 3. polymer

Answer 16

1. Corrosion, fatigue
2. Fatigue, aging
3. Hydrolysis and enzymization