Posted: October 27th, 2022

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 Respond to each post with 90-120 words and 1 reference. 

Post #1

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Spandex and vinyon are two fibers that are manufactured. Spandex is made out of a long-chain synthetic polymer that is composed of at least 85% of a segmented polyurethane (Houck and Siegel, 2015, p. 385). Although vinyon is also made out of a long-chain synthetic polymer, its composition is different from that of spandex. Vinyon is composed of at least 85% by weight of vinyl chloride units (Houck and Siegel, 2015, p. 385).

Cotton fibers and sisal fibers are two types of fibers that are natural. Cotton fibers are from a seed, and have a twisted, ribbon like appearance since they are made from layers that spiral around a central lumen (Houck and Siegel, 2015, p. 389). On the other hand, sisal fibers originate from a leaf. Sisal fibers have irregular lumen size, crystals, spiral elements, and annular vessels (Houck and Siegel, 2015, p. 389).

When analyzing the natural or manufactured fibers, the color of the fiber can be challenging. An analyst’s perception of color depends on numerous factors, such as genetics, age, and environment (Houck and Siegel, 2015, p. 397). For example, one’s perception of color can change depending on surrounding colors which can make other colors look lighter or darker. In order to identify the correct color, an objective method of color measurement must be used to check any visual comparison (Houck and Siegel, 2015, p. 398).

Human hair is examined under a microscope, and is categorized as being from the head, pubic, face, chest, axillary, eyelash/eyebrow, or limb (Houck and Siegel, 2015, p. 301). The characteristics of human hair varies depending on the region of the body that it came from. Hair from the head is usually even in diameter, while the diameter of hair from the limb is fine and tampered (Houck and Siegel, 2015, p. 302). Although characteristics, such as the diameter of a sample of hair, can help with identification, it can still be difficult to identify where on the body a piece of hair came from. For example, it can be sometimes difficult to identify hair as being from the chest or axillary (Houck and Siegel, 2015, p. 301). On the other hand, Manufactured fibers are identified with the use of polarized and nonpolarized light. While polarized light is the primary tool used to identify and analyze manufactured fibers, nonpolarized light can be used to identify accurate and direct characteristics of manufactured fibers (Houck and Siegel, 2015, pp. 390-391).

Post #2

Fibers have characteristics that when studied make them easy to distinguish between one another. Scientists generally classify fibers as either natural or manufactured. Animal fibers are one example of a natural fiber. For the most part animal fibers are made up of proteins. The purpose of said animal fibers is designed to protect the skin. These fibers typically absorb more water and are not as susceptible to changes in temperature. These same fibers are more susceptible to milder, rot, and fungi (Britannica, 2020). Manufactured fibers have different quite different qualities than manufactured fibers. According to Houck and Siegel (2015), synthetic fibers are created through a chemical process. Nylon for example is made up of a long sting of a synthetic polyamide. Fifteen percent or more of the linking’s are attached with two other aromatic rings (pp. 385-388). The challenge associated with examining fibers is the difficulty in tracing fibers back to an individual. The difficulty of using fibers as evidence lies in the quantity of fibers being used and produced. (Houck & Siegel, 2015, pp.383). The good news is that scientists have a way to analyze fibers and hairs.

One tool that forensic scientists often use is a polarized microscopic. Houck & Siegel (2015) note, polarized microscopes are the best way to analyze manufactured fibers. Forensic scientist can identify what the fiber is used for, the shape, and the material that was used in its production (p. 391). Scientists have other tools at their disposal as well, which, help get the most out of small clues whether they are fibers or hairs. Houck & Siegel (2006) note that often scientists often use DNA sequencing in addition to microscopic examinations to identify the source of the hair (p.306). The tools forensic scientists have at their disposal make it easier to narrow down possible suspects.

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