UGC NTA NET/JRF Exam, Forensic Science, December-2023

SBSE stands for Stir Bar Sorptive Extraction. This analytical technique uses a stir bar coated with a sorptive material to extract analytes from a liquid sample. The stir bar is placed in the sample, and as it stirs, analytes are absorbed onto the coating.

This method is advantageous because it combines extraction and concentration in one step, improving sensitivity and reducing solvent usage.

Stir Bar Solvent Extraction and Solvent Based Sample Extraction are incorrect because SBSE specifically refers to sorptive extraction, not solvent-based methods. Solvent Based Single Extraction does not accurately describe the technique.

A serum ethyl glucuronide concentration of greater than 5 mg/L indicates recent past consumption of an alcoholic beverage.

Ethyl glucuronide is a direct metabolite of ethanol and serves as a biomarker for alcohol intake. It is detectable in the blood for up to 80 hours after alcohol consumption.

Heroin, chloral hydrate, and chloroform do not produce ethyl glucuronide as a metabolite. Therefore, a high level of ethyl glucuronide specifically points to alcohol ingestion rather than the use of these other substances.

The backward hurling of injured tissue as a high-velocity rifle bullet enters the body is known as tail splash.

This phenomenon occurs due to the kinetic energy transfer and the temporary cavity created by the bullet. Ricochet refers to a bullet bouncing off a surface. Drilling is not related to tissue displacement.

Yaw describes the bullet's deviation from its flight path. Tail splash is unique to the energy dynamics of highvelocity projectiles and the resultant tissue disruption.

In hard contact wounds, the immediate edges of the entrance are seared by hot gases of combustion and blackened by soot embedded in the seared skin, which cannot be completely removed.

This happens when the muzzle of the firearm is pressed tightly against the skin, causing gases and soot to enter the wound. Incomplete wounds, near contact wounds, and intermediate range wounds do not exhibit this characteristic searing and embedding of soot.

Hard contact wounds display these features due to the close proximity and direct impact of the firearm's discharge.

Exit wounds are typically larger and can be stellate, slit-like, crescent, circular, or completely irregular. This variability is due to the bullet's energy and the body's resistance as it exits, often tearing the tissue in an irregular fashion.

Distant wounds and angled contact wounds do not exhibit such a wide variety of shapes and sizes. Intermediate large wounds do not refer to a specific wound type characterized by these features.

Exit wounds are influenced by the bullet's path and the body's anatomical structures, leading to their diverse appearances.

The primer consisting of a brass or gilding metal cup, a pellet containing a sensitive explosive, a paper dish, and a brass anvil with a single large flash hole in the bottom of the case is known as a Boxer primer.

Boxer primers are widely used in the United States and are known for their ease of reloading due to the single flash hole.

Berdan primers, on the other hand, have two smaller flash holes and an anvil built into the case, making them more difficult to reload.

Head stamp refers to the markings on the base of a cartridge case. Pin-fire is an older type of cartridge ignition system not commonly used today.

Black and white films are divided into four basic groups. These groups are based on their sensitivity and contrast characteristics, which include normal contrast films, high contrast films, low contrast films, and special purpose films.

Each type of film is suited for different photographic conditions and purposes, allowing photographers to choose the best film for their specific needs.

Two, three, and five groups do not accurately represent the classification of black and white films, which are traditionally categorized into these four main groups.

Polarized filters are used to reduce haze, glare, and reflected light when photographing near or over water surfaces. These filters work by blocking certain directions of polarized light, which helps in reducing reflections and enhancing contrast in the image.

Skylight filter No-1A is used to reduce the blue cast in outdoor photography. Yellow filter No-8 enhances contrast in black and white photography.

Red Filter No-25 is used for dramatic contrast effects in black and white photography but does not significantly reduce reflections. Polarized filters are specifically designed for this purpose.

The most widely used restrainer (antifoggant) during the development process of paper and film negatives is potassium bromide. Potassium bromide helps in preventing fogging and reducing unwanted background density, ensuring clearer and higher quality images.

Boric acid, amidol, and L-ascorbic acid are not commonly used as restrainers in photographic development. Boric acid is a weak acid used in various applications, amidol is a developing agent, and L-ascorbic acid is used as an antioxidant.

Potassium bromide's effectiveness as a restrainer makes it a standard choice in photographic processing.

The lowest temperature at which a liquid gives off sufficient vapour to form a mixture with air that will support combustion is known as the flash point.

The flash point is a critical parameter in assessing the flammability and safety of substances, particularly in industrial and safety contexts. End point refers to the final stage of a process or reaction.

Boiling point is the temperature at which a liquid turns into vapour. Cooling point is not a standard term in this context. The flash point is a specific measure of a liquid's potential fire hazard.