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MSc, School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment / A study has been conducted into the synthesis of 10wt% diamond/ mullite composites through two methods: First through the hot press sintering of alumina and silica in stoichiometric composition for 3:2 mullites (mullite formed in situ) at 1400, 1450 and 1500oC. Second through the sol/ gel process. The sol/ gel method only provided the basis for future development with no further discussion of the results while the hot press sintering method yielded composites with residual cristobalite and corundum phases. Achieved densities of the composites were 93.7, 94.6 and 95.8% of the theoretical density with respect to sintering temperatures of 1400, 1450 and 1500oC for compact samples by the first method. Hardness – measured by Vickers indentation – of the composites decreased with increase in temperature with 15.5 ± 0.33GPa achieved at the lowest sintering temperature investigated. The decrease in hardness was attributed to the structural degradation of diamond to non-diamond carbon forms with increase in temperature as observed from Raman spectra of each of the composites. X-ray traces showed an increase in the mullite content with increase in temperature. The fracture toughness of compacts initially hot press sintered from alumina and silica in stoichiometric composition for 3:2 mullite with no diamond added decreased with increase in sintering temperature with 4.75 ± 0.10MPa·m1/2 achieved at the lowest sintering temperature investigated. Further discussion to the structure and physical properties is presented.

by Tse Pak Kan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Tse Pak Kan. / ABSTRACT --- p.i / 摘要 --- p.iii / ACKNOWLEDGEMENTS --- p.iv / TABLE OF CONTENTS --- p.v / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.xiii / Chapter CHAPTER 1 --- DIAMOND AND DIAMOND-LIKE CARBON FILMS - BACKGROUND --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Properties of diamond and diamond like carbon --- p.1 / Chapter 1.2.1 --- Nature of diamond film --- p.1 / Chapter 1.2.2 --- Nature of diamond-like carbon films --- p.3 / Chapter 1.2.2.1 --- Diamond-Like Carbon Films --- p.6 / Chapter 1.2.2.2 --- Diamond-Like Hydrocarbon Films --- p.7 / Chapter 1.3 --- Application of diamond films --- p.8 / Chapter 1.4 --- Application of diamond-like carbon films --- p.9 / References for Chapter1 --- p.11 / Chapter CHAPTER 2 --- BACKGROUND OF THE STUDY --- p.12 / Chapter 2.1 --- Introduction --- p.12 / Chapter 2.2 --- Chemical Vapor Deposition --- p.15 / Chapter 2.2.1 --- CVD techniques --- p.17 / Chapter 2.2.2 --- Drawback of CVD techniques --- p.17 / Chapter 2.3 --- Ion beam Deposition --- p.18 / Chapter 2.3.1 --- Ion beam deposition techniques --- p.18 / Chapter 2.3.2 --- Literature review of ion beam deposition of diamond films --- p.19 / Chapter 2.3.2.1 --- Homoepitaxy of diamond films --- p.20 / Chapter 2.3.2.2 --- Heteroepitaxy of diamond films --- p.21 / Chapter 2.4 --- Objective of the present study --- p.23 / References for Chapter2 --- p.25 / Chapter CHAPTER 3 --- INSTRUMENTATION --- p.27 / Chapter 3.1 --- Introduction --- p.27 / Chapter 3.2 --- Low energy ion beam deposition system (LEIBS) --- p.27 / Chapter 3.2.1 --- Introduction --- p.27 / Chapter 3.2.2 --- Theory --- p.28 / Chapter 3.2.3 --- System Operations --- p.29 / Chapter 3.2.3.1 --- Ion Source --- p.30 / Chapter 3.2.3.2 --- Electrostatic Einzel Focusing Lens --- p.33 / Chapter 3.2.3.3 --- Auxiliary hot electron emitter --- p.33 / Chapter 3.2.3.4 --- Substrate stage with a heater block --- p.35 / Chapter 3.3 --- X-ray photoelectron spectroscopy (XPS) --- p.35 / Chapter 3.3.1 --- Background of XPS --- p.35 / Chapter 3.3.2 --- Theory --- p.35 / Chapter 3.3.3 --- Qualitative analysis --- p.39 / Chapter 3.3.3.1 --- Chemical Shift Peaks --- p.42 / Chapter 3.3.3.2 --- Auger Peaks --- p.43 / Chapter 3.3.3.3 --- Energy Loss Peaks --- p.43 / Chapter 3.3.4 --- Quantitative analysis --- p.44 / Chapter 3.3.4.1 --- Homogeneous system --- p.44 / Chapter 3.3.4.2 --- Layer Thickness Determination --- p.49 / Chapter 3.3.5 --- Instrumentation --- p.51 / Chapter 3.3.5.1 --- Monochromatized X-ray source --- p.53 / Chapter 3.3.6 --- Application to carbon films --- p.54 / Chapter 3.3.6.1 --- Compositional Analysis --- p.54 / Chapter 3.3.6.2 --- Angle-resolved analysis --- p.56 / Chapter 3.3.6.3 --- Energy Loss Structure --- p.58 / References for Chapter3 --- p.61 / Chapter CHAPTER 4 --- THE CHARACTERIZATION OF LOW ENERGY ION BEAM USING A COMPACT FARADAY CUP --- p.63 / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- Design of the Faraday cup with retarding lens --- p.63 / Chapter 4.3 --- Parameters control of energy distribution of ion beam --- p.66 / Chapter 4.4 --- Basic operation of the retarding lens energy analyser --- p.67 / Chapter 4.5 --- Effect of cathode voltage on energy distribution --- p.68 / Chapter 4.6 --- Effect of anode voltage on energy distribution --- p.71 / Chapter 4.7 --- Effect of sample bias on energy distribution --- p.71 / Chapter 4.8 --- Conclusions --- p.71 / References for Chapter4 --- p.76 / Chapter CHAPTER 5 --- OPTICAL PROPERTIES OF DLC FILMS DEPOSITED --- p.77 / Chapter 5.1 --- Introduction --- p.77 / Chapter 5.2 --- Experimental Procedure --- p.78 / Chapter 5.2.1 --- Sample pretreatment --- p.78 / Chapter 5.2.2 --- Improvement of current density --- p.80 / Chapter 5.2.3 --- Improvement of charging effect --- p.80 / Chapter 5.2.4 --- Experimental Plan --- p.82 / Chapter 5.3 --- Determination of thickness and growth rate of DLC films by alpha-step instrument --- p.83 / Chapter 5.4 --- Determination of microstructures in DLC films by Raman spectroscopy --- p.86 / Chapter 5.5 --- Determination of sp3/sp2 ratios in DLC films by infrared spectroscopy --- p.91 / Chapter 5.6 --- Determination of band gap of DLC by ultraviolet-visible transmittance spectrum --- p.94 / Chapter 5.7 --- Conclusions --- p.97 / References for Chapter5 --- p.99 / Chapter CHAPTER 6 --- GROWTH OF DIAMOND AND DIAMOND-LIKE FILMS USING DIFFERENT ION ENERGIES --- p.100 / Chapter 6.1 --- Introduction --- p.100 / Chapter 6.2 --- Experimental Procedure --- p.100 / Chapter 6.2.1 --- Sample pretreatment --- p.100 / Chapter 6.2.2 --- Improvement of heating source --- p.100 / Chapter 6.2.3 --- Experimental Plan --- p.101 / Chapter 6.3 --- Characterization of carbon films using XPS --- p.102 / Chapter 6.4 --- XPS-EELS of carbon films under different ion beam energy --- p.102 / Chapter 6.5 --- Surface morphology of carbon films --- p.106 / Chapter 6.6 --- Mechanism proposed --- p.108 / Chapter 6.7 --- Conclusions --- p.109 / References for Chapter6 --- p.111 / Chapter CHAPTER 7 --- INVESIGATION OF ADHESION PROPERTIES OF PERFLUORINATED LUBRICANTS ON AMORPHOUS CARBON OR CARBON NITRIDE FILMS --- p.112 / Chapter 7.1 --- Introduction --- p.112 / Chapter 7.2 --- Experimental Procedure --- p.113 / Chapter 7.2.1 --- Description of perfluorinated lubricant used --- p.113 / Chapter 7.2.2 --- Determination of the composition of a-C:H or CNX layer --- p.116 / Chapter 7.2.3 --- Thickness calculation --- p.116 / Chapter 7.3 --- Characterization of PFPE film --- p.121 / Chapter 7.4 --- Effects of molecular weight of PFPE on lubricant adhesion --- p.125 / Chapter 7.5 --- Effects of hydrogen content on lubricant adhesion --- p.128 / Chapter 7.6 --- Effects of end groups of PFPE on lubricant adhesion --- p.128 / Chapter 7.7 --- Verification of film thickness --- p.129 / Chapter 7.8 --- Conclusions --- p.129 / References for Chapter7 --- p.131 / Chapter CHAPTER 8 --- CONCLUSIONS --- p.132

Anemia occurs in 60% of patients with Shwachman Diamond Syndrome (SDS). Although bi-allelic mutations in SBDS cause SDS, it is unclear whether SBDS is critical for erythropoiesis and what the pathogenesis of anemia is in SDS. I hypothesize that SBDS protects early erythroid progenitors from p53 family member mediated apoptosis by promoting ribosome biosynthesis and translation. SBDS deficiency by vector-based shRNA led to impaired cell expansion of differentiating K562 cells due to accelerated apoptosis and reduced proliferation. Furthermore, the cells showed general reduction of 40S, 60S, 80S ribosomal subunits, loss of polysomes and impaired global translation during differentiation. An upregulation of the pro-apoptotic p53 family member, TAp73, was found in resting SBDS deficient cells; however, not in differentiating cells. These results demonstrate SBDS plays a critical role in erythroid expansion by promoting survival of early erythroid progenitors and in maintaining ribosome biogenesis during erythroid maturation independently of p53 family members.

Artificial cardiovascular implants are now made mainly from extruded polytetrafluroethylene (PTFE). However, the limited haemocompatibility of PTFE causes blood clotting and results in early replacement. Many techniques are being developed to improve the haemocompatibility of such devices. One of the most promising techniques is to coat the devices with nitrogen-doped diamond-like carbon (NDLC) thin films. However, the structure of NDLC and its effect on the haemocompatibility of the coated devices have not been fully investigated as required for practical applications. In this thesis, ion beam deposited DLC and Nitrogen doped thin films on PTFE were investigated in order to have a better understanding of the relationships between the structure and biomedical properties of the DLC thin films.<p> DLC and NDLC thin films were synthesized using ion beam deposition. Commercially available PTFE sheets, which are similar to the material used for vascular grafts, were used as substrates for the DLC thin films. Silicon wafers were also utilized as substrates for condition optimization and property comparison. Raman spectroscopy, atomic force microscopy, X-ray photo emission spectroscopy and scanning electron microscopy were used to study the structural and morphological properties of the coated surface. The results show that the ion beam deposited thin films have a very smooth surface and exhibit low coefficient of friction and high adhesion to the substrate. Low concentration of nitrogen doping in DLC improved surface hardness and reduced surface roughness. Higher concentration of sp3 hybridized bonds was observed in the DLC thin films on Si than those on PTFE. DLC coating decreased the surface energy and improved the wettability of PTFE films.<p> The haemocompatibility of the pristine and DLC coated PTFE sheets were evaluated by platelet adhesion technique. The platelet adhesion results showed that the haemocompatibility of DLC coated PTFE, especially NDLC coated PTFE, was considerably improved as compared with uncoated PTFE. SEM observations showed that the platelet reaction on the coated PTFE was minimized as the platelets were much less aggregated and activated.

Anemia occurs in 60% of patients with Shwachman Diamond Syndrome (SDS). Although bi-allelic mutations in SBDS cause SDS, it is unclear whether SBDS is critical for erythropoiesis and what the pathogenesis of anemia is in SDS. I hypothesize that SBDS protects early erythroid progenitors from p53 family member mediated apoptosis by promoting ribosome biosynthesis and translation. SBDS deficiency by vector-based shRNA led to impaired cell expansion of differentiating K562 cells due to accelerated apoptosis and reduced proliferation. Furthermore, the cells showed general reduction of 40S, 60S, 80S ribosomal subunits, loss of polysomes and impaired global translation during differentiation. An upregulation of the pro-apoptotic p53 family member, TAp73, was found in resting SBDS deficient cells; however, not in differentiating cells. These results demonstrate SBDS plays a critical role in erythroid expansion by promoting survival of early erythroid progenitors and in maintaining ribosome biogenesis during erythroid maturation independently of p53 family members.

Commutative Gröbner bases theory is well known and widely used. In this thesis, we will discuss thoroughly its generalization to noncommutative polynomial ring <em>k</em><<em>X</em>> which is also an associative free algebra. We introduce some results on monomial orders due to John Lawrence and the author. We show that a noncommutative monomial order is a well order while a one-sided noncommutative monomial order may not be. Then we discuss the generalization of polynomial reductions, S-polynomials and the characterizations of noncommutative Gröbner bases. Some results due to Mora are also discussed, such as the generalized Buchberger's algorithm and the solvability of ideal membership problem for homogeneous ideals. At last, we introduce Newman's diamond lemma and Bergman's diamond lemma and show their relations with Gröbner bases theory.

Commutative Gröbner bases theory is well known and widely used. In this thesis, we will discuss thoroughly its generalization to noncommutative polynomial ring <em>k</em><<em>X</em>> which is also an associative free algebra. We introduce some results on monomial orders due to John Lawrence and the author. We show that a noncommutative monomial order is a well order while a one-sided noncommutative monomial order may not be. Then we discuss the generalization of polynomial reductions, S-polynomials and the characterizations of noncommutative Gröbner bases. Some results due to Mora are also discussed, such as the generalized Buchberger's algorithm and the solvability of ideal membership problem for homogeneous ideals. At last, we introduce Newman's diamond lemma and Bergman's diamond lemma and show their relations with Gröbner bases theory.

Artificial cardiovascular implants are now made mainly from extruded polytetrafluroethylene (PTFE). However, the limited haemocompatibility of PTFE causes blood clotting and results in early replacement. Many techniques are being developed to improve the haemocompatibility of such devices. One of the most promising techniques is to coat the devices with nitrogen-doped diamond-like carbon (NDLC) thin films. However, the structure of NDLC and its effect on the haemocompatibility of the coated devices have not been fully investigated as required for practical applications. In this thesis, ion beam deposited DLC and Nitrogen doped thin films on PTFE were investigated in order to have a better understanding of the relationships between the structure and biomedical properties of the DLC thin films.<p> DLC and NDLC thin films were synthesized using ion beam deposition. Commercially available PTFE sheets, which are similar to the material used for vascular grafts, were used as substrates for the DLC thin films. Silicon wafers were also utilized as substrates for condition optimization and property comparison. Raman spectroscopy, atomic force microscopy, X-ray photo emission spectroscopy and scanning electron microscopy were used to study the structural and morphological properties of the coated surface. The results show that the ion beam deposited thin films have a very smooth surface and exhibit low coefficient of friction and high adhesion to the substrate. Low concentration of nitrogen doping in DLC improved surface hardness and reduced surface roughness. Higher concentration of sp3 hybridized bonds was observed in the DLC thin films on Si than those on PTFE. DLC coating decreased the surface energy and improved the wettability of PTFE films.<p> The haemocompatibility of the pristine and DLC coated PTFE sheets were evaluated by platelet adhesion technique. The platelet adhesion results showed that the haemocompatibility of DLC coated PTFE, especially NDLC coated PTFE, was considerably improved as compared with uncoated PTFE. SEM observations showed that the platelet reaction on the coated PTFE was minimized as the platelets were much less aggregated and activated.