Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Citric acid cycle wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Biosynthesis wikipedia , lookup
Biochemistry wikipedia , lookup
15-Hydroxyeicosatetraenoic acid wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Specialized pro-resolving mediators wikipedia , lookup
Butyric acid wikipedia , lookup
CERTIFICATE OF HIGHER EDUCATION IN COSMETIC SCIENCE DIPLOMA IN COSMETIC SCIENCE Paper One Date: 7th September 2012 Time: 2.30 pm to 4.30 pm INSTRUCTIONS TO CANDIDATES Answer FOUR questions. Start each question on a new page to aid marking. Write your DLC STUDENT NUMBER, PAPER NUMBER and QUESTION NUMBER on the top of each sheet. Do not write your name on the paper. Do not write on the back of the paper. Do not write in pencil. PAPER ONE 1. Answer all parts:Personal care and cosmetic formulations, whether they are cleansing or cosmetic products, are often referred to as colloidal systems. They are comprised of particles (solids or liquids) dispersed in an incompatible medium. An input of energy is often required to create the dispersion. a) Using the second law of thermodynamics as a guide, explain with the aid of a diagram the energy changes that occur over time for a colloidal dispersion. ( 5 Marks) Note: The second law of thermodynamics may be expressed by the following equation: G = A -TS Where G is the change in the free energy of the system, is the interfacial tension, A is the amount of new interfacial area created, T is the temperature and S is the entropy change. b) What are the most likely kinetic pathways to instability for an aqueous solid dispersion (slurry)? ( 2 Marks) c) With the aid of a free energy diagram, explain how you would stabilise the colloidal dispersion. Give two examples of how this could be achieved. ( 6 Marks) d) Linear block copolymers (surfactants) comprised of alternating hydrophobic and hydrophilic groups are often used to stabilise the dispersion. Describe how the polymer can adsorb onto the surface of the particle and which conformation provides optimum stabilisation. ( 4 Marks) e) Describe how the steric hindrance mechanism is able to stabilise the dispersion? ( 6 Marks) f) Give two examples of the potential disadvantages provided by this method. ( 2 Marks) PAPER ONE 2. Answer all parts:The urinary system is the principal means by which metabolic waste is removed from the body. a) List the organs which make up the urinary system and briefly describe their roles. You may include a diagram to illustrate your answer. ( 5 Marks) b) Describe the processes involved in the manufacture of urine. Relate these processes to their location in the nephron. ( 8 Marks) c) As one of the major roles of the urinary system is the maintenance of fluid and electrolyte balance within the body, urine volume varies according to the levels of hydration. Describe how aldosterone and antidiuretic hormone act to regulate the amount of urine produced. ( 8 Marks) d) Why would you not expect to find red blood cells in the urine? If blood is present what might this indicate? ( 4 Marks) 3. Answer all parts:a) Most of the natural gums are derived from naturally occurring plants or their seeds usually by aqueous extraction. Give examples of five natural gums used in the cosmetics industry and their natural origin. ( 5 Marks) b) Name three main commercial types of Carrageenan. What are the primary differences that influence their properties. ( 6 Marks) c) Suggest a thickener used in the manufacturing of the following three products giving reasons as to why you have made your suggestions:i) Toothpaste ii) Skin Cream/Lotion iii) Shampoo ( 9 Marks) d) What major rheological property would you expect magnesium aluminium silicate (MAS) gels to have. Give an example of the application area of MAS gels. ( 5 Marks) PAPER ONE 4. Answer all parts:The following gas chromatogram (Figure 1) shows the separation of standards of free fatty acids (FFAs) using a medium polar stationary phase. Further details of the separation are given in Table 1. Use your knowledge of chromatography to answer the questions. Column: Deactivated polyethylene glycol Column: Deactivated polyethylene (PEG), wax coated. glycolo(PEG), wax coated Temperature: 145 145 o C, isothermal Temperature: C, isothermal Carrier gas: Hydrogen Carrier gas: Hydrogen Flowrate: rate: min Flow 5 5mlml/ /min Detector: Flame ionisation Detector: Flame ionisation detector detectorvol: 1 μl Injection Injection vol: Split 1 μl50:1;block temp Injection: o Injection: Split 250 C 50:1;block temp 250oC 1 acetic acid 6 n-valeric acid acetic acid n-valeric acid 21propionic acid 76isocaproic acid 2 propionic acid 7 isocaproic 3 isobutyric acid 8 caproic acidacid acid 9 heptanoic 8 caproic 43n-isobutyric butyric acid acid acid 4 nbutyric acid 9 heptanoic 5 isovaleric acid acid 5 isovaleric acid Table 1 Conditions of separation Figure 1 Chromatogram of free fatty acids a) Describe the type of chromatography carried out and why the components separated under these conditions. ( 6 Marks) b) Briefly describe how the components were detected after eluting from the column. ( 3 Marks) c) Suggest an alternative mobile phase. ( 1 Mark ) d) What is the retention time of n-valeric acid? ( 1 Mark ) e) Approximately what volume of mobile phase would have passed through the column when isocaproic acid eluted? ( 2 Marks) f) Comment on the resolution of normal (n) and isomeric (iso) forms of the fatty acids. ( 3 Marks) (continued overleaf) PAPER ONE 4. (continued) g) Which component has the highest boiling point and explain your selection? ( 3 Marks) h) Assuming that you will carry out a survey of FFAs in oil samples using this technique, what precautions would you take to ensure that the results obtained were accurate and precise? ( 6 Marks) 5. Answer all parts:a) Differentiate between monosaccharides, disaccharides and polysaccharides. ( 3 Marks) b) Give two biologically significant examples of each. ( 6 Marks) c) Explain how monosaccharide molecules can be joined together to form polysaccharides. ( 6 Marks) d) Give a brief description of the uses of carbohydrates in biological systems. 6. (10 Marks) Answer all parts:Fatty alcohol ethoxylates are an important group of non-ionic surfactants used in cosmetic and personal care formulations. The hydrophobes (fatty alcohols) are obtained from both natural (fats and oils) and synthetic (petrochemicals) feedstocks. a) Using fatty alcohols as a starting point, describe the process used to manufacture alcohol ethoxylates. What are the advantages and the disadvantages of the process? ( 8 Marks) b) Detergency is described as the process to remove oily soils such as sebum and particulates from substrates (skin or hair). It can be broken down into four main steps. Briefly describe the mechanisms involved in the presence of a surfactant. ( 4 Marks) (continued overleaf) PAPER ONE 6. (continued) c) Oily soil removal can be described by the roll back mechanism. The process is determined by the interfacial tensions acting on the soil (oil droplet) and its influence on the contact angle formed by the droplet with the substrate. The forces acting on the oil droplet are described by the Young equation. OS, OL and SL are the respective interfacial tensions of the oil in contact with the substrate, the oil in contact with the liquid and the solid in contact with liquid. Discuss the significance of the equation to the wetting of the substrate by the wash liquid (water) and the spreading properties of the oil droplet on the surface of the substrate. In your answer make consideration of the relevance of the contact angle to the removal of the oil droplet from the substrate. What conditions must be met in order for the oily soil to detach from the substrate? ( 8 Marks) d) Although non-ionic surfactants are able to penetrate soils, they are often used in conjunction with ionic surfactants to provide optimum cleaning performance. Describe the mechanism for an anionic/nonionic mixed surfactant system to detach a particulate soil (solid) from the surface of the substrate. ( 5 Marks) PAPER ONE 7. Answer all parts:a) Draw a fully labelled diagram of a bacterial cell, including annotations of the functions of the parts labelled. ( 8 Marks) b) What do you understand by the term binary fission in terms of microbial growth? ( 4 Marks) c) State and discuss the factors that can influence the growth of microorganisms and how these can be used to control their growth. (13 Marks) 8. Answer all parts:a) Describe the chemical structure of a natural oil and a basic silicone oil, including diagrams of the structures. (14 Marks) b) For the silicone oils state the most common grades and how they differ. ( 2 Marks) c) In the formulation development of a premium skin care emulsion you are allowed to use both natural oils and silicones. Give examples of two natural oils and one silicone oil and explain their roles in your emulsion. ( 6 Marks) d) What are the potential hazards of using natural oils in an emulsion and how can you avoid these hazards? ( 3 Marks)