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2.5 Type of car seat material
To fabricate a ventilated car seat Nylon Fabric, Faux Vinyl, PCV, Vinyl, Faux Leather, Suede and Brushed Nylon is the common material used. Each material is described briefly in section 2.5.1 to 2.5.7.
2.5.1 Nylon Fabric
Nylon is a durable, hard-wearing upholstery fabric which comes in many colours. There are plain and patterned designs and you can choose a type which best suits the interior of your vehicle. Because nylon is weaved, it is harder to tear than some fabrics. It is also very stain resistant, providing you can wash out any spills before the dry. It is also the most popular form of fabric found in most automobiles. It is available in many colours and is the least expensive form of trim for your vehicle (Willis, 2014).
2.5.2 Faux Vinyl
This is actually a vinyl which takes on the characteristics of leather or suede or other types of material. It is hard-wearing and can have the appearance and shine of soft leather or the dullness of fabric trim. Faux vinyl is a mock vinyl which emulates the real article at a fraction of the cost (Willis, 2014).
2.5.3 PCV Leather
Commonly known as soft plastic, this is a vinyl style-material that is pliable and easy to form. It stretches well and is used in lower-end models of cars and vans. It can be coloured or made in black and white, but it is notorious for being sticky to sit on during the summer. Heat has a tendency to make the upholstery sweat and the driver of the vehicle is best advised not to wear shorts in the summer if their vehicle is lined with PVC (Willis, 2014).
2.5.4 Vinyl
Easy to wipe clean, durable and hard wearing, vinyl is another coonly used material in the making of automobile upholstery. It has similar properties to PVC but vinyl can soft, hard, pliable or firm. You might be aware that old LP records were made from vinyl but, because it is used in a different capacity for upholstery, it can be as soft as velvet although it will still make the skin sweat during hot periods of weather (Willis, 2014).
2.5.5 Faux Leather
Faux leather is a very versatile material that can be made to appear like almost anything. People have covered their car seats in fake crocodile skin, fake snake’s skin and even dinosaur prints. It behaves like leather and is easy to wipe clean. Spillages can be quickly dealt with so faux leather doesn’t stain easily and is very durable (Willis, 2014).
2.5.6 Suede
Cloth-based suede fabrics are a nice choice for an automobile interior. Suede is soft to the touch and feels like brushed cotton. This automobile fabric is not used as often because it stains easily and it not as durable for many types of automobile use (Willis, 2014).
2.5.7 Brushed Nylon
Brushed nylon is soft and warm and ideal for an interior seat cover or door trim. It is a thick fabric that is usually just under a ¼ thick when used in vehicles. It seems well and is a firm, durable material which is quite hard to tear (Willis, 2014).

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2.6 GENOME PLASTICITY AND EVOLUTION OF ESCHERICHIA COLI
Like all life forms, new strains of E. coli evolve through the natural biological processes of mutation, gene duplication, and horizontal gene transfer; in particular, 18% of the genome of the laboratory strain MG1655 was horizontally acquired since the divergence from Salmonella. E. coli K-12 and E. coli B strains are the most frequently used varieties for laboratory purposes. Some strains develop traits that can be harmful to a host animal. These virulent strains typically cause a bout of diarrhea that is often self-limiting in healthy adults but is frequently lethal to children in the developing world. (Futadar et al., 2005). More virulent strains, such as O157:H7, cause serious illness or death in the elderly, the very young, or the immunocompromised.
The genera Escherichia and Salmonella diverged around 102 million years ago (credibility interval: 57–176 mya), which coincides with the divergence of their hosts: the former being found in mammals and the latter in birds and reptiles. (Wang et al., 2009). This was followed by a split of an Escherichia ancestor into five species (E. albertii, E. coli, E. fergusonii, E. hermannii, and E. vulneris). The last E. coli ancestor split between 20 and 30 million years ago.
The long-term evolution experiments using E. coli, begun by Richard Lenski in 1988, have allowed direct observation of genome evolution over more than 65,000 generations in the laboratory. For instance, E. coli typically do not have the ability to grow aerobically with citrate as a carbon source, which is used as a diagnostic criterion with which to differentiate E. coli from other, closely, related bacteria such as Salmonella. In this experiment, one population of E. coli unexpectedly evolved the ability to aerobically metabolize citrate, a major evolutionary shift with some hallmarks of microbial speciation.
2.7 INCUBATION PERIOD
The time between ingesting the STEC bacteria and feeling sick is called the “incubation period”. The incubation period is usually 3–4 days after the exposure, but may be as short as 1 day or as long as 10 days. The symptoms often begin slowly with mild belly pain or non-bloody diarrhea that worsens over several days. HUS, if it occurs, develops an average of 7 days after the first symptoms, when the diarrhea is improving.

2.7.1 DISCOVERY OF ANTIBIOTICS
• History of antibiotics – 1
19th century:Louis Pasteur & Robert Koch
• History of antibiotics – 2
Plant extracts
– Quinine (against malaria)
– Ipecacuanha root (emetic, e.g. in dysentery)
Toxic metals
– Mercury (against syphilis)
– Arsenic (Atoxyl, against Trypanosoma)
• Dyes
– Trypan Blue (Ehrlich)
– Prontosil (azo-dye, Domagk, 1936)
• History of antibiotics – 3
Paul Ehrlich
• started science of chemotherapy
• Systematic chemical modifications
(“Magic Bullet”) no. 606 compound = Salvarsan (1910)
• Selective toxicity.
• Developed the Chemotherapeutic Index
• History of antibiotics – 4
Penicillin- the first antibiotic – 1928• Alexander Fleming observed the
killing of staphylococci by a fungus (Penicillium notatum)
• observed by others – never exploited
• Florey & Chain purified it by freeze-drying (1940) – Nobel prize 1945
• First used in a patient: 1942
• World War II: penicillin saved 12-15% of lives
• History of antibiotics – 5
Selman Waksman – Streptomycin (1943), was the first scientist who discovered antibiotic active against all Gram-negatives for examples; Mycobacterium tuberculosis
– Most severe infections were caused by Gram-negatives and Mycobacterium
tuberculosis, extracted from Streptomyces – extracted from Streptomyces
– 20 other antibiotics include. neomycin, actinomycin
2.8 CHARACTERISTICS OF ANTIBIOTICS
According to the Oxford Dictionary, the term Antibiotics encompasses medicines (such as penicillin or its derivatives) that inhibit the growth of or destroys microorganisms. Antibiotics are naturally occurring substances that exhibit inhibitory properties towards microbial growth at high concentrations. (Zaffiri, et al., 2012).
-Antibiotics are selective in their effect on different microorganisms, being specific in their action not only against genera and species but even against strains and individual cells. Some of these agents act mainly on gram-positive bacteria, while others inhibit only gram-negative ones.
-Some antibiotics are produced by some organism, from different strains of penicillin.
-Bacteria are sensitive to the antibiotic which enable them to developed resistance after contact, for several periods.

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2.9 ROLE OF ANTIBIOTICS
Based on the clinical use of antibiotics, it may appear that these compounds play a similar role as microbial weapons in nature, yet this seems unlikely due to the fact that the concentrations used in the clinical setting are significantly higher than that produced in nature (Fajardo et al., 2008). Due to experimental evidence, it makes more sense to see antibiotics as small, secreted molecules involved in cell-to-cell communication within microbial communities.
(Martinez, 2008). Diverse Studies have been conducted in which different antibiotics and antibiotic-like structures were administered to different bacterial species at levels below the compounds minimum inhibitory concentrations (MIC). (Fajardo et al., 2008). that was

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