Natural fibers can be harvested from
Plants animals and minerals
The shiny nature of silk can be related to
It's ability to refract light
What characteristics of cotton make it a great source of fiber for clothing?
The fibers are easily woven and dyed
Mineral fibers such as asbestos are very durable. These fibers are used in all of the following except: rope,shingles,floor tiles,brake liners
Rope
True/false: synthetic fibers do not contain any natural fibers.
They are used in the production of carpet fibers
They are man made
They are formed by combining monomer compounds into polymer molecules
False
True
True
True
A characteristic of a natural fiber is that they
Are affected by microscopic organisms
Which of the following observations are used to help identify a specific fiber?
-smell of the burned fiber
-on contact with the flame does the fiber cool or melt?
-color and structure of the residue left after the fiber burns
-all of the above
All of the above
Fibers are an excellent source of trace evidence because
They are easily transferred from victim to suspect, they are often overlooked by a suspect, they can be easily collected and stored
T/F the shaft of the hair is considered class evidence in a trial
T
T/F hair is composed of a protein called cellulose
F
T/F all hairs on the head of a person are identical
F
T/F the cortex may contain pigment granules
T
The hair shaft is composed of the cuticle, cortex, and
Medulla
What factors are used to calculate the medullary index of the hair?
Width of the medulla and width of hair
Which characteristics is found in typical Asian hair?
Dark medulla
Human hair has what type of cuticle?
Imbricate
Which parts of a hair can be analyzed for DNA?
Root
The cuticle scales of the hair always point toward the
Tip of the hair
The period of active hair growth is called the ____stage
Anagen
Although variations can occur, which best describes Northern European hair?
Straight with Evenly distributed granules
Which of the following is most likely a result of hair bleaching?
A yellowish tint to the hair
Why is hair considered class evidence?
It cannot be traced back to a single person unless you don't have the root which has the DNA
Describe the structure of the hair
Had is growing from the follicle and has an inner medulla surrounded by a correct and then the cuticle
What are two ways animal hair differs from human?
Medullary index and cuticle pattern
What are some examples of mineral fibers
Asbestos, rock wool, fiberglass
Which phase lasts about three weeks
Catagen
What is the hair shaft composed of?
Cortex, medulla, cuticle
What can be used to connect suspect and victim to a crime scene
Fiber evidence
Name two synthetic fibers
Nylon polyester spandex
3 wats to test for identification of fibers
Burn test, chemical test, thermal decomp, stain test
What are the three cuticle patterns?
Imbricate, spinous, coronal
What type of evidence can hair provide for placing an individual at a crime scene
Corroborative evidence
What race is the only race to have a continuos medulla
Mongoloid
What are three major categories of cross-section
Oval, crescent moon, round
What is hair pigmented by?
Melanocytes
Where is medulla found? What might it look like
In the center- absent, continuous, fragmented, interrupted, stacked
How do you individualize a fiber
Chemical comp, color dye, being torn
How is hair color determined,
Genetics
Which incidents can cross transfer occur in?
Hit and run, contact, crime
During which phase of growth does hair begun to grow
Anagen
Do fibers have probative value?
Yes because blood, DNA, and it can create connections
Can a piece of fabric be individualized to a specific government
A fabric can be individualized
Which cross section is curly
Oval
what are some o the cross-sections for fibers
round, trilobal, dogbone, dumbbell
T/F polymers and monomers are structurally different
true- monomers make up polymers
if hair is forcibly removed can DNA still be attached?
yes
Which stage does hair naturally fall out?
telogen
how many fiber sources will be lost after 4 hours?
80%
how big/ what is a micrometer
one millionth of a meter
1/1000000
what is a blend
fabrics mixed together usually warped and weft fibers
t/f DNA is still attached when hair is forcibly removed?
true
T/F human hair usually has stacked Medulla
false
T/F a human root is generally frayed
false
what is the difference betweeen warp and weft?
warp is east to west
wept is north to south
there are more than 2000 different dye formulations?
true- 7000
what kind of incidents are fibers considered important evidence in?
homicide, assault
what are filaments?
single strands of materials twisted all together to makeup a thread of fiber
what are the three basic weave patterns?
plain, twill, satin
what is a method of separating components of mixtures based on preferential adsorption or partitioning of components in a gas, liquid, or solution
chromatography
what is a fabric
fibers interwoven together
does a human or animal have a thicker medulla?
animal
what is the name of the extra pigment in a redhead?
tricociterin
what are two types of sweat glands in the skin?
eccrine and apochrie
what are the three cuticle types
coronal, spinous, and imbricate
name the medulla types
interrupted, fragmented, continuous, stacked, absent
what protein is in hair?
keratin
where is mitochondrial DNA found?
shaft
where is nuclear DNA found?
root
examples of nylon
seatbelts, ropes
examples of polyester
suits, carpets, ropes
ex of rayon
table cloths, drapes
ex of spandex
athletic clothing, bathing suites
what muscle causes goosebumps
arrector pili
what classifies black people, white people and Asians
negroid, Caucasoid, mongoloid
wat gives paint adhesive qualities/
resin
what is the most common paint examined by scientists?
automobile
what is in paint to prevent bacterial growth
additives and fillers
what is paint used for
protection, decoration, added functionality
what are the classification of fibers
natural, manufactured, synthetic
a biochemical polymer formed by linking amino acids
polypeptide
a series of carbon atoms connected by oxygen atoms
polyethers