Graham's law states that gas diffusion rate is inversely proportional to square root of molecular weight. Heavier gases diffuse more slowly than lighter ones. Law applies only to molecular effusion through holes, not diffusion between gases
Diffusion through plane sheets follows linear concentration distribution with time. Barrer developed method to determine diffusion constant from time lag measurements. Holstein's solution provides alternative method for small time intervals. Variable surface concentrations can be modeled using exponential or linear equations. Diffusion from limited volume stirred solution follows partition factor approach
Cell membrane is flexible but acts as a formidable barrier. Lipid bilayer allows some small molecules but blocks large water-soluble ones. Transport occurs through channels, facilitators, and pumps
Plasma membranes are 5-10 nm thick and form a fluid mosaic model. Main components include phospholipids, cholesterol, proteins, and carbohydrates. Phospholipids have hydrophilic heads and hydrophobic tails. Cholesterol is present in the membrane's core
Textbook covers physical origins and rate equations of heat transfer. Discusses relationships between heat transfer and thermodynamics. Provides methodology for analyzing heat transfer problems
Atoms can move between atomic sites in materials with defects. Energy barrier (activation energy) prevents atoms from moving between sites. Diffusion probability depends on temperature and energy barrier height