Forensics cheat sheet, Cheat Sheet of Environmental science

Download Forensics cheat sheet and more Cheat Sheet Environmental science in PDF only on Docsity! “BER ANAL?S § / detcesi=s k/vat-alaniva' sellealinguishes = / \ yellow las d = anton place in lon, shlicks aay — lqutis ~ spandex lope Star: nae: alse bend bear =polyeser sted: hole nea lane contruge turn ng —= rescue) OS Ss oak leel wool ‘netural/animal ha eacter Rayon Under Microscope Glass Fibers Magresion zne | simore Talay nina Water Lost <n >, fen sae sna Sg Nie rN, ~ Alcubak Test ‘Hopper Wire Test Rubbing W Ach \e AN < ae SS 8 Vinegar Ne , * Hydiogen Pare Deer Rabbit Cat How to ID polymers: start with unknown polymer: put it in water: Floats: put in 46% isopropyl alcohol Floats: put in Vegetable oil Floats:PP Sinks:LDPE Sinks:HDPE Sinks: put in 10% NaCl Floats:PS Sinks:Saturated NaCl Floats:PC or PMMA Sinks: PETE or PVC PETE vs PVC:PETE=tough, PVC=flexible PC vs PMMA:PC is used in bulletproof glass, PMMA is used in glasses Based on the evidence gathered, we concluded that the culprits were ___ and ____, and that _____ and _____ were not responsible for the crime. There is much evidence to support our conclusion. ______ was found at the scene of the crime, and _____ frequently works with _____. In addition, _____ hair was found at the crime scene and _____ has a pet _____. Furthermore, _____’s fingerprints were found at the scene of the crime. [DISCUSS ALL OTHER RELEVANT EVIDENCE HERE]. In addition, there was not enough evidence to point to other suspects. [EXPLAIN WHY HERE]. We were able to rule out ______ because _______. (DO THIS FOR EACH OF THE OTHER SUSPECTS) Therefore, it can be concluded that _____ and ______, were responsible for the crime, while _____ and ______ were not. How to Identify Fibers: Wool - Wool is the most commonly used animal fiber. The fiber is obtained from the soft, hairy covering of sheep and sometimes goats. Under the microscope, the wool fiber looks like a long cylinder with scales on it. The fiber is very curly and springy. Cloth made from wool includes cashmere, camel's hair, alpaca, covert cloth, flannel, gabardine, mohair, serge, tweed and worsted. Silk - Silk, another common animal fiber, was once quite popular but has been replaced to a great extent by such synthetic fibers as Nylon, Orlon, and Dacron. Silk is made by the mulberry silk worm when spinning its cocoon. Under the microscope, the silk fiber appears as a thin, long, smooth and lustrous cylinder. Cloths made from silk include brocade, brocatelle, chiffon, crepe, velvet, crepe de Chine, foulard, lame, moiré, satin, taffeta, tulle, and falle. Cotton - Cotton is the most widely used plant fiber. Cotton fibers are the hairs found on the seeds of the cotton plant. If possible, obtain a cotton boll on its stem. Examined under a microscope, the cotton fibers (use a few strands of absorbent cotton) will look like a flattened, irregular, twisted ribbon. Many high school chemistry and physical science textbooks (and books on identifying textiles) have excellent pictures of fibers as seen through a microscope. Clothes made from cotton area cheesecloth, organdy, chintz, gingham, crinoline, muslin, percale, calico, velveteen, seersucker, some poplin, sail cloth and canvas. Most cotton thread has been treated to make it smooth and lustrous; this is done by stretching the cotton and immersing it in a concentrated solution of cold sodium hydroxide (lye). Cotton treated in this manner is said to be mercerized. Linen - Another common plant fiber is linen, which comes from the flax plant. This fiber is long, lustrous, and smooth. Under the microscope it looks like a bamboo can, with jointed cells and split, tapered ends. Point out that linen is often used to make handkerchiefs, tablecloths, napkins, summer clothing and blouses. Jute and Hemp - Jute and Hemp, other plant fibers, are not as fine as cotton and linen, and are used to make carpet backing rope, twine and sacks. Rayon - Rayon is one of the first successful artificial fibers. It is made from cellulose. When manufactured, the rayon fibers resemble silk. Under the microscope, the rayon fiber looks like a smooth, lustrous cylinder. Rayon can be made into cloth that is hard to distinguish from silk, cotton, linen, or wool. Celanese is one form of rayon. Synthetic Fibers - Today there is a wide variety of synthetic fibers; all have trade names such as Nylon, Orlon, Dacron, Vinyon, Aralac, Acrilan, Velon, Dynel, Banlon and Lycra. Like rayon, these fibres resemble silk, and under the microscope look like smooth, lustrous cylinders. Synthetic fibers are easily identified because of their uniform thickness (the thickness of natural fibers varies). Synthetic fibers area made into fabrics that have special properties.. Glass - Glass and asbestos can also be spun into thread and woven into fabrics. Glass fibers are made by stretching melted glass into fine filaments, which are spun into thread for weaving into cloth. Lightweight glass fibers are used to make long lasting windows curtains, drapes, and lamp shades. Heavier glass fabrics are used to make fireproof theater and school curtains. Asbestos - Asbestos is the name given to a group of minerals that occur naturally as masses of strong, flexible fibers that can be separated into thin threads and woven to make asbestos cloth. These fibers are not affected by heat or chemicals and do not conduct electricity. Asbestos cloth was used in fireproof theater curtains and protective suits for use by firefighters. It was also used as a building material, brake pads and a range of other products. It is now know that the fibers of asbestos are a dangerous irritant. Even exposure to small amounts of asbestos dust can lead to a range of illnesses such as asbestosis, a serious lung inflammation caused by asbestos exposure, and Mesothelioma a cancer of the chest and abdomen. Although asbestos products are rarely made these days, they can still be found, particularly in old buildings.