#forensicnotes

[forensicfield]

Questions- What is difference between Poison, Toxin And Venom?

Answer- Poison, toxin, venom are terms for any substance that injures the health or destroys life when absorbed into the system. ☣ Poison: Poison, in biochemistry, a substance, natural or synthetic, that causes damage to living tissues and has an injurious or fatal effect on the body. ☣ Toxin: A toxin is a poison produced by an organism. ☣ Venom: Venom is especially used of the poisons secreted by certain animals, usually injected by bite or sting.

Question- What quantity of a poison would be necessary to produce a lethal out-come in a human victim?

Answer- There are several considerations to keep in mind for poisoning. Studies revealed that small doses of a substance might be harmless or beneficial, whereas larger doses could be toxic. This is now known as the dose-response relationship, a major concept in toxicology. A poison is any substance that can cause illness or death when ingested in small quantities. This definition excludes the multitude of substances that cause damage if ingested in large quantities. For example- A dose of aspirin (acetylsalicylic acid) that is harmless to an adult may be poisonous to an infant. Similarly, an elderly person’s tolerance of a substance may be much lower than that of a healthy young adult. Lethal Amount of poison is also depend on person, poison and many other factors, such as; Lethal dosage often varies depending on the method of administration; for instance, many substances are less toxic when administered orally than when intravenously administered.

[forensicfield]

Analysis of Fiber Colors and Dyes

➿ The vast majority of fibers used in commercial applications are colored.

➿ Fiber color is one of the most important properties in the comparison of fibers.

〽️ There are a variety of methods for characterizing the color of the dyes in the fibers. They fall into three major categories:

1.) Visual:The visual method is the simple observation and comparison of the fiber colors by use of the unaided eye. Visual comparison is easy, fast, accurate and non- destructive. It is a crucial first step in any fiber comparison, as many otherwise similar fibers can be excluded from consideration by color.

2.) Chemical:Chemical methods, which include thin layer chromatography and high performance liquid chromatography, address the make-up of the dyes used to color the fiber. (This latter statement is an important distinction: analyzing the color of a fiber is not the same as analyzing the dyes used to color that fiber.)

3.)Instrumental- Instrumental analyses include microspectrophotometry in the UV and/or visible ranges and, more rarely, spectrophotometric measurement of fluorescence.

[forensicfield]

Cartridge Cases

📌 Cartridge cases are usually made of brass, a composition of 70% copper and 30% zinc.

📌Less commonly, they are made of steel or aluminum.

📌 Zinc andplastic materials have been used experimentally.

📌 Brass, plastic, and paper are used for shot-shell tubes.

📌 The main function of the cartridge case is to expand and seal the chamber against rearward escape of gases when the cartridge is fired. When a brass cartridge is fired in a weapon, the gas pressure produced by the burning of the propellant expands the case tightly against the walls of the chamber. If the brass is tempered to the correct hardness, it will spring back to approximately its original dimensions and make the case easy to extract. If the brass is too soft, it will not spring back and will make extraction difficult. If the brass is too hard, brittle, it will crack.

👉 There are three general shapes for cartridge cases: 🕵️‍♂️ Straight, 🕵️‍♂️ Bottleneck, 🕵️‍♂️ and, Tapered.

Almost all pistol cartridges are straight, whereas almost all rifle cartridges are bottle-necked. The bottle-neck design permits more powder to be packed in a shorter, fatter cartridge than would be possible in a straight cartridge, where the lumen is approximately the diameter of the bullet. Cartridges with tapered cases are virtually obsolete.

Watch video for more information: https://youtu.be/Y6VUcFocLoI

[forensicfield]

Handguns:

There are four basic types of handguns: 1. Single-shot pistols 2. Derringers 3. Revolvers 4. Auto-loading pistols (automatics)

1. Single-shot pistols- A single-shot pistol has one firing chamber integral with the barrel, which must be loaded manually each time the weapon is to be fired.

2. Derringers- They are a variant of single-shot pistols. Derringers are small pocket firearms having multiple barrels, each of which is loaded and fired separately. The traditional derringer has two barrels.

3. Revolvers- The revolver is the most common type of handgun in the United States. Revolvers have a revolving cylinder that contains several chambers, each of which holds one cartridge. The cylinder is rotated mechanically so as to align each chamber successively with the barrel and firing pin. The first revolver was produced by Samuel Colt in 1835–1836.

4. Auto-loading pistols (automatics)- Auto-loading or automatic pistols make up the fourth category of handguns. The term “automatic pistol” is a misnomer, as this form of pistol is an auto-loader in which the trigger must be pulled for every shot fired. Regardless of the correct terminology, however, these weapons are invariably called “automatics” or just “pistols.”

[forensicfield]

Question- What is Forensic Glass Examination?

Answer- 👉Forensic examination of glass consists of the examination of two or more fragments to determine whether they have a common origin. 

👉Identifying broken glass fragments having a common source to the exclusion of all other sources may only be done if they can be physically matched together.

Question- How will you analyse Glass fragments in lab?

Answer- 👉Submitted samples from a crime scene must first be confirmed as glass.  ✔Differentiating glass from plastic is done by examining hardness, solubility, and observation with a polarized light microscope.  ✔Once confirmed as glass, the examiner will perform an analysis of

📌physical properties, such as; color, fluorescence, thickness, curvature, density, 📌optical properties, such as; Refractive Index 📌and chemical composition. 

✔ no further comparison is needed if any difference between questioned and known samples is found during analysis.

[forensicfield]

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