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The Wonderful World of Hairs and Fibers

The Wonderful World of Hairs and Fibers. Different Scopes used to analyze hair and fiber. Compound light Comparison Dissecting Polarized Scanning Electron Microscope (SEM). Stages of Hair “Life”. Anagen Growing stage Up to 6 years possible Root shaped like “flame”

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The Wonderful World of Hairs and Fibers

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  1. The Wonderful World of Hairs and Fibers

  2. Different Scopes used to analyze hair and fiber • Compound light • Comparison • Dissecting • Polarized • Scanning Electron Microscope (SEM)

  3. Stages of Hair “Life” • Anagen • Growing stage • Up to 6 years possible • Root shaped like “flame” • Hair grows ~1cm/month (1” every 10 weeks)

  4. Stages of Hair “Life” • Catagen • ~3 weeks long • Dormant, resting stage • Root gets longer and thinner

  5. Stages of Hair “Life” • Telogen • ~6 months • Root  • Club shaped • Pushes out and is shed • Lose approximately 70 hairs/day

  6. Human Hair Parts • 1. Root • 2. Follicle • 3. Shaft • 4. Tip 4 2 3 1

  7. Human Hair Parts • 1. Distal (tip) • 2. Proximal (root end) • 3. Medulla • 4. Cuticle (contains scale pattern) • 5. Cortex 1 4 3 5 2

  8. Scale patterns • Imbricated • Mosaic • Petal • Pectinate • Chevron

  9. Medulla Types • Continuous • Fragmented • Intermittent/interrupted

  10. Medullary Index of Hair • To find the MI • Diameter of medulla/hair shaft diameter • Humans = <1/3 • Other animals = >1/2 • Classify Medulla as: • Continuous, Interrupted, Fragmented, or Absent

  11. Example Medulla Patterns that can be seen • Lattice • Vacuolated • Uniserial • Multiserial

  12. Deer, Dog & Muskrat hair Deer Muskrat

  13. Which is Caucasian, Negroid, Mongoloid Head Hair? Caucasian, Europeans, Mexicans, Middle Easterners: oval to round Negroid, Africans oval to flat Mongoloid, Orientals, American Indians: round

  14. Pulled Hair v. Shed Hair Anagen Stage Pulled Hair Telogen stage

  15. Razor, Cut hair & Split hair Split Razor Cut

  16. Human eyebrow

  17. Burned hair

  18. Buckling of hair seen in pubic hair

  19. Hair match • This is the view that a comparison scope can give when comparing two matching hairs

  20. Dust Mite The small things in life Eyelash mites Bedbug feeding on flesh

  21. Fibers

  22. Types of fibers • Natural fibers • Animal fibers are most common at crime scene • Man-made

  23. Natural fibers • Animal: • Wool from sheep most common • Goats, camel, alpaca, rabbit, mink, llamas, beaver • Plant: • Cotton most common • Flax (linen), ramie, sisal, jute, hemp • Excrement: • Silk from silkworm (cellulose from mulberry leaves) • Mineral: • Asbestos

  24. Cotton fibers cross-section

  25. Wool fibers v. Cotton fibers Cotton Wool

  26. Flax Fibers

  27. Hemp fibers

  28. Silk fibers • Raw thrown • Wild silk

  29. Asbestos fibers

  30. Man-Made fibers • Regenerated fibers • Machine made from natural materials like cotton or wood • 1910 rayon, then acetate, then triacetate • Synthetic fibers • Most fibers are made synthetically from chemicals • 1939 nylon, then polyester and acrylic • Shape or cross-section can determine value of the fiber; manufacturer specific

  31. Nylon fiber cross sections

  32. Acetate Fibers

  33. Nylon fibers

  34. Orlon Fibers

  35. Polypropylene fibers

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