The amino acid content of bone decreases slowly after death
It can be assessed by thin layer chromatography technique
Fresh bones contain atleast 15 amino acids
If the number of amino acids is found to be less than 7, the bone is alteast 100 years old
If proline and hydroxy proline are absent, it indicates that the bone is very old

Barium carbonate is a whitish powder
It is used as a rodenticide
Symptoms develop within half an hour of poison ingestion
Fatal dose is 0.8g

Symptoms of barium carbonate poisoning:

Gastrointestinal

Diarrhoea
Vomiting
Abdominal pain

Cardiac

Arrhythmia
Hypertension
Heart failure

Areflexia, tetraplegia, flaccid paralysis

Sparrow’s foot marks are bizarre shaped lacerations that result from the face coming in contact with shattered windshield glass
It is a commonly seen in front seat passengers in road traffic accidents

Reference:
Textbook Of Forensic Medicine And Toxicology: Principles And Practice By Vij

Burtonian line, also known as lead line is a clinical manifestation of chronic lead poisoning
It is a stippled blue line seen in 50-70% of patients with chronic lead poisoning
It is manifested as a bluish black line due to epidermal deposition of lead sulphate at the junction of the gums with the teeth (not seen on the teeth)
Similar pigmented lines are seen in poisoning with mercury, copper, silver, bismuth and iron poisoning
Other features of chronic lead poisoning include pallor (anemia), constipation, paralysis and lead encephalopathy

It is a set of 4 conditions as set by the Harvard School of Medicine for diagnosis of irreversible coma. They are:

Unreceptivity and unresponsiveness
Lack of movements or breathing
Absent reflexes
Flat electroencephalogram (confirmatory)

These conditions also are to be met:

Body temperature >= 32 C
Not under the influence of CNS depressants 

3 types of brain death are:

Cortical / cerebral death
brain stem death
whole brain death

It is also called secondary drowning or near drowning. It refers to a peron who was resuscitated after drowning and survives for 24hours. He may develop hypoxemia resulting in brain damage, cerebral edema, pulmonary edema, pneumonitis, myocardial anoxia, cardiac arrhythimas, electrolyte imbalance, metabolic acidosis, hemoglobinuria, fever and sepsis. Death occurs in about 20% of victims. 5-10% of those who survive can have severe neurological defects.

In dry drowning, water does not enter the lungs. Due to rapid entry of water into the nasopharynx and larynx, the larynx undergoes immediate sustained spasm, which is the cause of death. There may be production of mucus plugs and froth. It occurs mainly in childer and adults under the influence of alcohol or sedative hypnotics.

It is also known as primary drowning. In this, large amounts water enter the lungs. The person experiences severe chest pain. Death occurs in minutes due to cardiac arrest or ventricular fibrillation.

Types of drowning are:

Wet drowning
Dry drowning
Secondary drowning / post immersion syndrome / near drowning
Immersion syndrome / hydrocution / submersion inhibition