Imran Saleem

Question 1

Particle size influences?

Answer 1

Powder flow
Powder mixing
Solubility and stability
Dissolution
Aerosol deposition

Question 2

Where do inhaled particles deposit?

Answer 2

Bigger than 5microns - mouth and trachea
1-5microns - sediment in the bronchi and bronchioles
Less than 1micron - diffuse into alveoli

Question 3

What is convection when referring to powder mixing?

Answer 3

Transfer of large groups of powder from one part of the mixer to another

Question 4

What is shear when referring to powder mixing?

Answer 4

Layer of material move or flow over one another

Question 5

What is diffusive mixing when referring to powder mixing?

Answer 5

Particles fall under gravity through voids created

Question 6

When does powder segregation or demixing take place?

Answer 6

When the particles are different size, shape or density

Question 7

What is percolation segregation?

Answer 7

When smaller particles fall through voids between larger particles

Question 8

What is trajectory segregation?

Answer 8

When larger particles have a greater kinetic energy and travel greater distances than smaller particles

Question 9

How would you overcome segregation?

Answer 9

Sieving
Milling of components - size reduction
Produce an ordered mix

Question 10

How do you decrease the size of a particle?

Answer 10

Ball milling - rotate particles around in a ball and will take parts off each other and get smaller
Fluid energy milling

Question 11

What particle size is required when ball milling?

Answer 11

1-500 micrometers

Question 12

What particle size is required when using the fluid energy mill?

Answer 12

1-50,000 micrometers

Question 13

In what sort of way does particle size affect dissolution?

Answer 13

Small particles dissolve more rapidly than larger particles

Question 14

What mechanism is used to evaluate the degree of mixing?

Answer 14

HPLC - high performance liquid chromatography

Question 15

How high must the funnel be held when measuring the angle of repose?

Answer 15

10cm

Question 16

How can you measure powder flow?

Answer 16

Measure the angle of repose

Question 17

What technique can you use to work out the particle distribution?

Answer 17

Sieving

Question 18

At what particle size is sieving viable?

Answer 18

45-1000 micrometers

Question 19

What is the sieving equivalent diameter?

Answer 19

The size of a sphere that will just pass through the mesh of a particular sieve

Question 20

When should you use the sieving method?

Answer 20

Materials analysed have good flowability
Range of different densities present
Material is robust
Material must me dry

Question 21

When should using a sieve not be used?

Answer 21

When dealing with fine powders
Particles are fragile
The powder easily acquires an electrical charge
When material easily adheres to the sieve

Question 22

List the features of a SEM?

Answer 22

3D image
Able to capture images
Can measure to nm range
Great depth of field

Question 23

List the features of a TEM?

Answer 23

2D images
Able to capture images
Can measure to nm range

Question 24

What are the range for the SEM, TEM and light microscope?

Answer 24

SEM - 0.05-1000 micrometers
TEM - 0.001-0.05 micrometers
Light microscope - 1-1000 micrometers

Question 25

What is the range a coulter counter?

Answer 25

0.1-1000 micrometers