Lynne Wong's PhD thesis

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2.1.3 Methodology A mass of 2 kg each of dry trash, green leaves and immature cane tops without attached foliage above the natural breaking point of cane stalk, were shredded separately in a Jeffco cutter-grinder (Fig 2.1). Subsequently 20 kg of clean cane stalks, which had previously been chipped coarsely in a cane chipper (Fig 2.2), were shredded. The finely divided clean cane was well mixed; a sub-sample of 1329 g was taken, 329 g of which was analysed for pol % cane and fibre % cane by the Société de Technologie Agricole et Sucrière de Maurice (STASM) method (Anon., 1991). Simultaneously, one kg of the clean cane was subjected to a pressure of 20 MPa (200 bar) for two minutes in a Pinette Emidecau hydraulic press (Fig 2.3) to obtain first expressed juice. Distilled water (330 mL) was sprayed onto the pressed cake and a second pressing carried out to obtain “mixed juice”. The mass of the cake was weighed as bagasse, of which 50 g were analysed for moisture content and 150 g for Brix and pol (for method, see Appendix 1). Fibre % bagasse was taken as 100 – moisture % bagasse – Brix % bagasse. Mercuric iodide juice preservative was added to the mixed juice at the rate of 0.5 mL L -1 before analysis for Brix by a refractometer (Fig 2.4), pol and Clerget sucrose by a polarimeter (Fig 2.5) by the STASM method (Anon., 1991), sulfated ash content (for method, see Appendix 2), and glucose, fructose and sucrose by high performance ion chromatography making use of the official International Commission for Uniform Methods of Sugar Analysis (ICUMSA) method for molasses modified for juices (Schäffler, 1994) using lactose as internal standard. Clerget purity was obtained by dividing Clerget sucrose by the Brix, expressed as a percentage. The experiment was repeated with shredded dry trash, green leaves and cane tops added separately to sub-samples of the shredded clean cane so that the added EM constituted 5%, 10% and 20% of the total mass which was 1329 g. The experiment was concluded with a second sub-sample of clean cane alone, to ascertain that no deterioration of the cane had occurred. This was assessed by ensuring that the pol of the second mixed juice was not less than 0.05% lower than the first one, and the average of the two sets of clean cane data was taken. As an indication, the eleven “mixed juice” samples were processed not later than two hours after the start of the experiment. The composition in terms of moisture, Brix and pol of shredded dry trash, green leaves and cane tops were determined as for bagasse (Appendix 1). Six trials were carried out on fresh supply of cane and EM. 33
2.1.4 Results The analytical results of the six trials with addition of dry trash, green leaves and cane tops to clean cane are presented on CD (file: Raw data for Tables 2.2-2.4.xls). Averages of the six trials with addition of dry trash, green leaf and tops are shown in Tables 2.2 – 2.4. The first series of data in each category of clean cane and various additions of EM refer to the first trial, and so on. It is of note that Clerget sucrose results are in agreement with HPIC sucrose. The composition of the extraneous matter is compared to that of clean cane in Table 2.5 (samples from Trial 1 were not analysed). It is worth pointing out that the moisture of dry trash collected could be twice as much on a wet day than on a dry day (34.4% compared to 17.9%). In Table 2.5, apparent purity is obtained by dividing pol % by Brix %, expressed as percentage, and non-pol is taken as: Brix - pol. The influence of extraneous matter in cane is indicated by the mean analytical data compiled on the quality of mixed juice, bagasse and cane. Glucose, fructose and ash contents of mixed juice were used to calculate mixed juice-based target purity, to which were added 4.5 units to predict Clerget purity of molasses (Table 2.6), as explained earlier. Calculation of SJM sucrose recovery % sucrose in mixed juice leads to (i) g sucrose in sugar/kg cane, which after subtracting the assumed sucrose losses in filter cake and undetermined losses totalling 0.21% cane, yields sucrose recovery % cane, and (ii) g sucrose in molasses/kg cane and mass of molasses % cane. The data summarised in Table 2.6 enabled the calculation of mill extraction, boiling house recovery and overall recovery (Table 2.7) since, by definition, mill or press extraction is the percentage mass of sucrose originally in the cane that has been extracted into the mixed juice. Boiling house recovery is by definition, the percentage of sucrose in the mixed juice that passes into the sugar produced, and overall recovery is the percentage of sucrose in the cane that passes into the sugar produced. Brix and pol data of mixed juice in Tables 2.2 – 2.4 also allowed the determination of commercial cane sugar (CCS), which is computed from the following Australian equation (Anon., 1984): CCS = 3 2 ( fibre % cane 5) 1 100 - ( fibre % cane 3) ⎡ 100 - + pol⎢ ⎣ 100 in which pol and Brix refer to the first expressed juice. ⎤ ⎥ ⎦ ⎡ + − Brix 2 ⎢ ⎣ 100 ⎤ ⎥ ⎦ 34
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THE BRIX-FREE WATER CAPACITY AND SO
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dissolved and hydrated waters, and
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ACKNOWLEDGEMENTS I am particularly
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Page 1.5 THE DELETERIOUS EFFECTS OF
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Page 2.2 THE PHENOMENON OF BRIX-FRE
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Page 3.4.3.3 Cane tops 83 3.4.4 Cha
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4.3.3 Temperature at which Brix-fre
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4.6.1 Materials 143 4.6.1.1 Samples
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CHAPTER 6. PROPERTIES OF THE SORBED
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APPENDIX 3. CALCULATIONS LEADING TO
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LIST OF FIGURES Page Figure 1.1. Fi
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Figure 3.1. Glucose and fructose an
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Figure 5.11. Residual plots for the
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total adsorbed water (m) and the pr
Page 29 and 30: Table 2.18. Moisture content in sug
Page 31 and 32: Page Table 4.4. Results of the dete
Page 33 and 34: Page Table 4.24. Analysis of varian
Page 35 and 36: Page Table 5.13. Table 5.14. Equili
Page 37 and 38: Table 6.3. Heat of sorption of the
Page 39 and 40: GLOSSARY OF TERMS Absorption is the
Page 41 and 42: Filterability of a raw sugar is mea
Page 43 and 44: Sorption is the generic term used w
Page 45 and 46: LIST OF MAIN SYMBOLS Symbol Descrip
Page 47 and 48: s c s Slope of Caurie I isotherm pl
Page 49 and 50: number of 255, and cane land covere
Page 51 and 52: Nouvelle Mon In Trésor ustrie and
Page 53 and 54: Figure 1.3. Cane sampling by core s
Page 55 and 56: In Mauritius, most of the sugar fac
Page 57 and 58: are: cane tops, dry and green leave
Page 59 and 60: 1.4 TRENDS IN CANE QUALITY RECEIVED
Page 61 and 62: campaign was launched to encourage
Page 63 and 64: The level of extraneous matter in c
Page 65 and 66: In Australia (Cargill, 1976), cane
Page 67 and 68: The effect of soil on factory perfo
Page 69 and 70: leaves increased the level of impur
Page 71 and 72: • From 1976 to 1980, when the pro
Page 73 and 74: Clerget purity of molasses 40 Clerg
Page 75 and 76: CHAPTER 2. IMPACT OF EXTRANEOUS MAT
Page 77 and 78: Since the extrapolated purity of mo
Page 79: Figure 2.1. Jeffco cutter grinder.
Page 83 and 84: Table 2.3. Analytical results of re
Page 85 and 86: Table 2.5. Composition of dry trash
Page 87 and 88: Table 2.7. Predicted factory perfor
Page 89 and 90: Boiling house recovery 91.0 89.8 89
Page 91 and 92: 0 5 10 15 20 % EM in cane y = 0.572
Page 93 and 94: % EM in cane 0 5 10 15 20 0 -2 -4 -
Page 95 and 96: 1 y = 0.020 (% D) R 2 = 1.00 = 0.03
Page 97 and 98: % EM in cane 0 5 10 15 20 0 -2 y =
Page 99 and 100: esulting in 0.015 unit sucrose loss
Page 101 and 102: 2.2.1 Experimental procedure Cane m
Page 103 and 104: filter paper, rejecting the first f
Page 105 and 106: Table 2.9. Effect of increased addi
Page 107 and 108: Table 2.11. Effect of increased add
Page 109 and 110: Table 2.13. Effect of increased add
Page 111 and 112: various components such as stalk fi
Page 113 and 114: in the presence of dry leaves, if c
Page 115 and 116: Table 2.17. Moisture content in sug
Page 117 and 118: CHAPTER 3. SEPARATION OF THE SUGAR
Page 119 and 120: Table 3.1. It can be seen that the
Page 121 and 122: Table 3.2. Fibrous physical composi
Page 123 and 124: R 579 R 570 M 1557/70 M 1400/86 74
Page 125 and 126: loosen the fibre. The woody core is
Page 127 and 128: agitate the mixture in the pot, and
Page 129 and 130: Figure 3.7. Custom-built fibre-pith
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The extraction of fibres starting f
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pre-treatment in a Jeffco cutter-gr
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Figure 3.19. Stalk cake washed free
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not have many dry leaves attached t
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Table 3.5. Masses of cane samples a
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Table 3.7. Masses of cane samples a
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Table 3.9. Masses of cane component
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3 57.6 126.3 23.7 97.2 31.1 53.8 11
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Table 3.12. Material loss (%) from
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3.5.3 Fibre/pith ratios in cane com
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Table 3.15. Effect of extraneous ma
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Snow (1974) investigated the season
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from Figure 2.9 that the change in
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Table 3.18. Fibre % cane results by
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110
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(a). Dry leaf (b). Green leaf (c).
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dry fibre, or a factor, is used in
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Steuerwald (1912) applied sucrose s
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solution/fibre ratio was lowered fr
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leave some residual moisture on the
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instead of 150 g of 10° Brix sucro
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Table 4.2. Determination of Brix-fr
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Table 4.3. Comparison of Brix-free
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Table 4.4. Results of the determina
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In order to test for homogeneity of
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Table 4.7. Results of the repeat de
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The experiment was repeated with th
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e any residual moisture in the samp
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By means of the same technique, Won
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was still hot. Since the filter was
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value determined could be corrected
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Qin and White’s finding was confi
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A sample size of 3.5 g with 75 g co
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Figure 4.4. Fibre samples drying in
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- One large fibre sample (rind) of
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Table 4.18. Brix-free water values/
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Table 4.20. Brix-free water values/
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4.7.3 Statistical analysis It is es
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Table 4.23. Analysis of variance (B
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pointing out that at 52 weeks old,
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The crop of R 570 sampled in 2001 w
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4.7.4. Estimated Brix-free water co
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The main difference in the two sets
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Table 4.27. Predicted Brix-free wat
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4.8 SUMMARY AND CONCLUSIONS An anal
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component parts, and verify the Bri
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3) Thermodynamic, water in equilibr
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Langmuir (1916, 1917, 1918) propose
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to determine the moisture sorption
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Table 5.1. Some commonly used isoth
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Lomauro et al. (1985) found that wi
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and on agricultural products such a
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Bruijn (1963) studied the mass incr
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After measuring the EMC of dry corn
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approached, that is, either by adso
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Table 5.4. Water activity (a w ) of
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5.6.3 Procedure to determine equili
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5.6.4 Results and discussion An exa
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Table 5.8. Equilibrium moisture con
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Table 5.10. Equilibrium moisture co
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Table 5.12. Equilibrium moisture co
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30 o C 45 o C 55 o C 60 o C Water w
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m/m of 96% activity, a w (g/100g dr
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vaporisation generally decreases fr
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30 o C isotherm 45 o C isotherm 55
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4 0 Stalk fibre 5 0 Stalk pith 5 0
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5.6.4.4 Fitting of sorption models
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Table 5.19. Parameters of the sorpt
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Modified GAB Kuhn Iglesias - Chirif
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Table 5.28. Classification of resid
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Stalk fibre Stalk pith Rind fibre 4
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5.6.4.5 Calculated EMC values of re
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Table 5.30. Calculated equilibrium
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m/m of 96% Table 5.32. Calculated e
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Table 5.33. Parameters of the Hailw
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CHAPTER 6. PROPERTIES OF THE SORBED
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where m is the equilibrium moisture
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6.2 THE NUMBER OF ADSORBED MONOLAYE
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6.3 TOTAL SOLID SURFACE AREA AVAILA
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Thus, for each cane component of ea
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abscissa. For each moisture level (
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A similar procedure was followed to
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10 0 Stalk fibre Stalk pith Rind fi
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Moreover, if T β > T hm the proces
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Table 6.5. Characteristic parameter
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Binding energy/kJ (kg mol) -1 2 0 0
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6.8 CALCULATION OF BOUND WATER AND
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The values of K 1 , K 2 and W were
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Table 6.7. Separation of the total
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Table 6.7. (Contd.) Sample 30 o C 4
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3 0 S talk fibre 4 0 Stalk pith 3 0
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3 0 Reconstituted cane at 30 o C 3
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when water is added to dry wood, wh
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It is evident that in some cases ma
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The number of adsorbed monolayers,
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Data in Tables 2.9 and 2.11 show th
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particular fibre is systematically
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Anon. (1985b). Laboratory manual fo
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Blanchi R.H. and A.G. Keller (1952)
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Day D.L. and G.L. Nelson (1965). De
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Heyrovsky J. (1970). Determination
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Kuhn I.J. (1964). A new theoretical
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Madamba P.S., R.H. Driscoll and K.A
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Prinsen Geerligs, H.C. (1897). Stud
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Sing K.S.W., D.H. Everett, R.A.W. H
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Van der Pol C., C.M. Young and K. D
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Lynne Wong's PhD thesis

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