It is an insulator.
A permeable solution is one that allows substances to pass through it, such as water or other molecules. This can refer to a variety of materials, such as membranes or filters, that have openings or pores that permit the movement of substances. Permeable solutions are often used in filtration processes or in controlling the flow of substances in various applications.
Haversian canals
Nuclear Pores
Intervertebral foramina
High Lipid Solubility
The measure of variation in particle sizes of filter and ion exchange media. The coefficient is defined as the the ratio of the sieve size that will permit passage of 60% of the media by weight to the sieve sieve size that will permit passage of 10% of the media material by weight.
Materials with high atomic numbers, such as lead, and dense substances like bone or metal, can block the passage of x-rays due to their ability to absorb and scatter the radiation. The level of attenuation depends on factors like the thickness and density of the material through which the x-rays are passing.
You don't unless your a Pharmaceutical company with a DEA permit to manufacture controlled substances.
A birthday party, and you can get a learners permit to drive and vote in the United States of America.
A substance that does not permit the passage of x-rays or other radiant energy is characterized as being opaque. This means that the substance absorbs or scatters the radiation, preventing it from passing through. Examples of opaque materials include lead and thick concrete.
Bombs, illegal drugs, endangered species, human body parts (without a permit), poisonous substances (again without a permit or consignment note). Basically anything illegal.