Synthesis of novel surface active agents via copper mediated living radical polymerisation : synthetic and mechanistic study

The synthesis of polyethylene glycol)-based surface active agents was undertaken via copper mediated living radical polymrisation. In a first approach, polyethylene glycol) was used as macroinitiator for the synthesis of polyethylene glycol) methyl ether-b-poly(methyl methacrylate) (MeOPEG-b- PMMA) block copolymers. The living character of the polymerisation was demonstrated, but MeOPEG was found to be a slow initiator. In a second approach, MeOPEG was used as a methacrylate macromonomer (MeOPEG-MA). Graft polymers were obtained by polymerisation in toluene and water, and various block copolymers, aiming to increase the hydrophobicity character of the final molecules, were also synthesised. The kinetics of the polymerisation was then studied, and various oxygen containing molecules were found to influence the polymerisation by polarity effect on the solution and potential competitive coordination with the ligands on the copper catalyst. Finally, the physical properties of the block and graft copolymers synthesised were tested. Thermal analyses, surface properties of the PMMA block copolymers and aggregates formation in aqueous solution were investigated

Development of an Actuation System for Automatic Immobilization Boards for Breast Cancer Radiotherapy

학위논문 (석사)-- 서울대학교 대학원 : 융합과학기술대학원 융합과학부, 2018. 2. 예성준.유방암 방사선 치료는 일반적으로 1일 1회씩 6-7주에 걸쳐 총28-33회로 수행된다. 정확한 방사선 치료를 위해 매회 같은 자세로 치료를 받아야 하고, 이를 위해 상체고정장치가 사용된다. 상체고정장치에는 수동으로 조절되는 여러 개의 조절부가 있으나, 짧은 시간에 환자를 치료 자세로 세팅하기 위해서 실제로는 2-3개의 조절부만이 사용되고 있다. 환자에 따라서 초기에 설정된 치료 자세로 자동으로 고정이 가능하다면, 세팅 시간이 줄어들면서도 모든 조절부를 사용하므로 방사선치료의 정밀성을 높일 수 있게 된다. 본 연구는 현재 유방암 방사선치료에 사용되고 있는 상체고정장치를 개조하여 자동화시키는 것을 목표로, 각 조절부를 구동하기 위한 구동시스템을 개발하는 것을 주 연구내용으로 하고 있다. 이를 위해, 병원에서 가장 널리 사용되고 있는 C 사의 상체고정장치를 사용하였다. 또한 CT 촬영 시 금속 음영이 생기지 않도록 금속 부품을 배치하여 구동시스템을 설계하였다. 환부에 정확히 방사선을 조사하기 위해서 지지부들의 위치는 정확하게 설정되어야 하므로, 본 연구에서는 dual absolute encoder 측정방식을 제안하였고, 이를 구동시스템 일부에 적용하였다. 시작품 제작 및 실험을 통해 dual absolute encoder를 적용한 구동시스템으로 상체고정장치를 자동화 시키는 것이 가능함을 보였다.Radiation therapy for breast cancer is conducted a total of 28–33 times and is generally administered once a day over a period of 6–7 weeks. In order to correctly expose the tumors to radiation, the patient setup should be the same every timefor this reason, an immobilization board is utilized. An immobilization board for breast cancer radiotherapy has many possible manual adjustments, but usually only 2–3 adjustments are used, so as to quickly fix the patient setup. However, for proper radiation therapy, the system of adjustments should be configured in a precise way. If it were possible to automatically set all the adjustments to each patients specific setup as initially configured, then it would take less time to fix each patient, and the radiotherapy could be administered more precisely by employing all the necessary adjustments. This study aims to remodel and automate a currently used immobilization board. The main focus is on developing an actuation system to drive the adjustments. Company Cs immobilization board, which is widely used in hospitals, is employed as the base frame. In designing the actuation system, its metal parts were specifically placed so that metal artifacts do not appear while the CT scan is being conducted. This study proposes a dual absolute encoder measurement and purposefully applies this method to the adjustments. The automation of an immobilization board with this system is demonstrated through prototyping and experimentation.제 1 장 서 론 1 제 1 절 연구 배경 1 제 2 절 연구 내용 5 제 2 장 구동부 절대위치 측정 시스템 6 제 1 절 관련연구 및 듀얼 절대엔코더 시스템 6 제 2 절 이론적 고찰 8 1) 감속비가 정수일 때 최소 분해능 10 2) 감속비가 정수가 아닐 때 최소 분해능 11 3) 최대분해능 13 제 3 절 시뮬레이션 14 제 4 절 실험 및 결과 고찰 16 1) 감속비가 정수일 때 실험 결과 17 2) 감속비가 정수가 아닐 때 실험 결과 21 제 3 장 상체고정장치 자동화를 위한 구동시스템 26 제 1 절 관련연구 및 연구추진방향 26 1) 관련연구 26 2) 연구추진방향 27 제 2 절 각 자유도의 자동화를 위한 메커니즘 설계 28 1) 상박 받침대 위치 조절 메커니즘 설계 29 2) 엉덩이 받침대 위치 조절 메커니즘 설계 34 3) 머리 받침대 위치 조절 메커니즘 설계 35 제 3 절 상박 조절부의 직교좌표 변환 36 제 4 절 실험 및 결과 고찰 41 1) 실험 장치 제작 41 2) 듀얼 절대 엔코더 실험 및 결과고찰 48 3) CT 영상 금속 음영 실험 및 결과고찰 50 4) 위치 반복성 실험 및 결과고찰 51 제 4 장 결론 54 참고문헌 56 부록 59 Abstract 62Maste

Thermodynamic Approach to Fatigue Failure Analysis in Metals and Composite Materials

Fatigue is a dissipative process and must obey the laws of thermodynamics. In general, it can be hypothesized that the degradation of machinery components is a consequence of irreversible thermodynamic processes that disorder a component, and that degradation is a time dependent phenomenon with increasing disorder. This suggests that entropy —a fundamental parameter in thermodynamics that characterizes disorder— offers a natural measure of component degradation. The majority of the existing methods for prediction of fatigue are limited to the study of a single fatigue mode, i.e., bending or torsion or tension-compression. Further, the variability in the duty cycle in a practical application may render many of these existing methods incapable of reliable performance. During this research, we put forward the idea that fatigue is a degradation process and that entropy is the most suitable index for assessing degradation. That is, tallying irreversible entropy is more reliable and accurate than many of the other methods presented in the existing papers. We show that in processes involving fatigue, for a given material (metal and composite laminate), there exists a unique threshold of the cumulative thermodynamic entropy beyond which fatigue fracture takes place. This threshold is shown to be independent of the type of the fatigue process and the loading history. This exciting result is the basis of the development of a Fatigue Monitoring Unit (FMU) described in this research. We also propose a general procedure for assessment of damage evolution based on the concept of entropy production. The procedure is applicable to both constant- and variable amplitude loading. Empirical relations between entropy generation and damage evolution for two types of metals (Alumunium 6061-T6 and Stainless steel 304) and a woven Glass/Epoxy composite laminate are proposed and their potential for evaluation of fatigue damage are investigated

Analysis of Circular Dichroism and Linear Dichroism Spectroscopy

Circular Dichroism (CD) and Linear Dichroism (LD) spectroscopies measure the difference in absorption between left and right circularly polarized light and parallel and perpendicular linearly polarized light as a function of wavelength respectively. CD and LD are popular biomedical physics techniques used to determine structural changes in biomolecules. This dissertation addresses improvements made to the measurement of CD and LD signals by characterizing the transfer function of the spectrometer. Shot noise, stray light and dark current were characterized. A new model for the measurement of the CD signal involving the presence of static birefringence was derived and tested by implementation of novel techniques used to measure the phase-difference amplitude and static birefringence in the photoelastic modulator (PEM) crystal. The model was tested by measuring the fractional change in the signal on Camphorsulfonic Acid (for CD) and Chrysazin (for LD). It is hoped that this study will impact how CD and LD are measured and analyzed in the future.  Ph.D

Transient electric birefringence of macromolecular systems

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The transient electric birefringence method, i. e. the transient Kerr effect, has been employed to study the optical, electrical and geometrical properties of three macromolecular systems. An apparatus is described in which the birefringence could be measured when d. c. electric field pulses (of duration 1μs to 5s and strength up to 50 KV/cm) and a. c. electric field pulses (of duration greater than 5 ms, of frequency up to 20 kHz, and strength up to 3 KV/Cm) were applied to solutions of macromolecules. Both the linear and quadratic optical systems have been employed to measure the induced birefringence. A theoretical analysis and review of the errors implicit in such measurements is given, with suggested alignment and calibration procedures. For the first time in electro-optic work, a data-logging system and computer program have been developed and employed, and enabled the automatic recording of transient responses with subsequent high speed data analysis. Measurements have been made on a polypeptide poly – β – benzyl – 1 – aspartate in two solvents. These show how the method can be used to study a rigid macromolecule. A novel investigation was made on the interaction of an anionic surfactant, sodium dodecyl sulphate, with a flexible polymer, polyvinylpyrrolidone. The large variation of Kerr constant observed with addition of surfactant indicated a great potential use of this method for studying polymer surfactant interactions. An aqueous suspension of the bacteria E. coli was also studied, but changes in turbidity and not birefringence were the origin of the observed effects. Novel practical methods of investigation, and turbidity calculations carried out with the aid of a computer enabled size parameters and electrical properties to be determined for E. coli. For the first time such results were in agreement with electro-optic light scattering measurements.Science Research Counci

Copper Phenoxyl Complexes

The work described in the following was inspired by radical copper enzymes such as Galactose Oxidase (GO). GO catalyses the two-electron oxidation of terminal alcohols to the corresponding aldehydes using air oxygen. Transfer of two electrons is possible, since GO contains two magnetically coupled one-electron redox centres: a tyrosylate ligand from the apo-protein, which exists either in the tyrosylate or the tyrosyl radical form and is bound to a copper ion possessing two stable oxidation states (+I and +II). The catalytic activity of GO can be assigned to the Cu-OTyr (Tyr = Tyrosine, or more general Cu-Oaryl) motive, which is also found in all complexes synthesised and characterised in this thesis. The ligands specifically designed for this study, contain substituted, non-substituted or aromatically enlarged phenoxy moieties and belong to various compound classes: O,N,O pincer ligands, O,O',N donor ligands, salen type ligands, phenol-substituted triazole ligands, phenalenone ligands, benzoquinone ligands und acridine ligands. All of them were used to synthesise Cu(II) complexes, selected ligands (e.g. O,O',N, donor ligands) were additionally coordinated to Ni(II), Zn(II), Fe(II), Fe(III) and Co(II). All compounds were fully characterised using NMR or EPR spectroscopy, UV/vis/NIR-absorption spectroscopy, emission spectroscopy, cyclic voltammetry, spectroelectrochemistry, elemental analysis and XRD. These studies focus on (a) the electrochemical properties of the two one-electron redox couples Cu(II)/Cu(I) und [PhO•+]/[PhO], (b) the influence of ligand- and complex structure on both redox pairs and (c) the catalytic activity of the complexes resulting from their electrochemical properties. The latter was investigated by test reactions using benzyl alcohol as substrate and an in situ generated catalyst. Furthermore, detailed investigations on reactions yielding the active radical species Cu(II)-[OPh•+] under catalysis conditions were performed using a phenol-substituted triazole ligand system. Two methods were compared, one starting from a Cu(I) precursor, which is oxidised by air oxygen to yield the copper radical complex and the second starting from Cu(II) complexes which undergo a disproportionation reaction forming the active radical species and a Cu(I) byproduct

Computing Intelligence Technique and Multiresolution Data Processing for Condition Monitoring

Condition monitoring (CM) of rotary machines has gained increasing importance and extensive research in recent years. Due to the rapid growth of data volume, automated data processing is necessary in order to deal with massive data efficiently to produce timely and accurate diagnostic results. Artificial intelligence (AI) and adaptive data processing approaches can be promising solutions to the challenge of large data volume. Unfortunately, the majority of AI-based techniques in CM have been developed for only the post-processing (classification) stage, whereas the critical tasks including feature extraction and selection are still manually processed, which often require considerable time and efforts but also yield a performance depending on prior knowledge and diagnostic expertise. To achieve an automatic data processing, the research of this PhD project provides an integrated framework with two main approaches. Firstly, it focuses on extending AI techniques in all phases, including feature extraction by applying Componential Coding Neural Network (CCNN) which has been found to have unique properties of being trained through unsupervised learning, capable of dealing with raw datasets, translation invariance and high computational efficiency. These advantages of CCNN make it particularly suitable for automated analyzing of the vibration data arisen from typical machine components such as the rolling element bearings which exhibit periodic phenomena with high non-stationary and strong noise contamination. Then, once an anomaly is detected, a further analysis technique to identify the fault is proposed using a multiresolution data analysis approach based on Double-Density Discrete Wavelet Transform (DD-DWT) which was grounded on over-sampled filter banks with smooth tight frames. This makes it nearly shift-invariant which is important for extracting non-stationary periodical peaks. Also, in order to denoise and enhance the diagnostic features, a novel level-dependant adaptive thresholding method based on harmonic to signal ratio (HSR) is developed and implemented on the selected wavelet coefficients. This method has been developed to be a semi-automated (adaptive) approach to facilitate the process of fault diagnosis. The developed framework has been evaluated using both simulated and measured datasets from typical healthy and defective tapered roller bearings which are critical parts of all rotating machines. The results have demonstrated that the CCNN is a robust technique for early fault detection, and also showed that adaptive DD-DWT is a robust technique for diagnosing the faults induced to test bearings. The developed framework has achieved multi-objectives of high detection sensitivity, reliable diagnosis and minimized computing complexity