Hydroxyapatite (HA) based bioceramics have been developed to treat bone defects for the last 30 years. Doping HA with elements is a common approach to increase mechanical strength, biocompatibility and osteointegrity. Bone morphogenetic protein (BMP)-containing bioceramic composites enhance osteointegrity and induce bone formation. Strontium (Sr) is currently used to treat osteoporosis clinically as this element inhibits bone resorption and stimulates bone formation. In this study, HA was doped with silicon (Si), Sr, BMP-2 and evaluated in cortical bone defect healing. Ceramics were produced and tested mechanically after characterization. Sr release from ceramics was assessed. Ceramics were further evaluated in in vitro and in vivo conditions. X-ray diffraction analysis results of HA were in line with the literature and Sr-Si-HA ceramics showed similar intensities with HA. Ceramics had 36.9 to 41.6% porosity. Compression strength of Sr1000-Si-HA ceramics was 117.5 MPa which was more than that of the other groups. Consistent Sr release was observed in the Sr1000-Si-HA and the Sr250-Si-HA groups. Sr1000-Si-HA and Sr250-Si-HA ceramics showed higher cellular proliferation rates than the other groups in vitro. BMP addition increased alkaline phosphatase activities and DNA amounts. BMP-Sr-Si-HA group presented higher (0.304&plusmn / 0.02 g/cm2) bone mineral density values than the other groups 4 weeks after implantation however differences between groups were not significant in vivo. Sr-Si-HA and BMP-Sr-Si-HA composites stimulated new bone formation at cortical bone defects of tibia according to micro computerized-tomography and histological results. Findings of this study promote future research on Sr containing bioceramics in treatment of orthopedic problems.

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名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成4年10月19日 狩野良雄氏の博士論文として提出された

The effect of local defect on thin film mechanical properties is studied in this thesis. The molecular dynamics (MD) is employed to simulate and analyze the relation between intermolecular strength and deformation in the nanoindentation test. The variation of hardness and elastic modulus are simulated from the load-displacement response and the projected area of contact at the maximum load. In this study, Tersoff potential function is employed to describe the molecular behavior of nano-scale carbon and silicon films. The MD models of the diamond indenter and film are applied in the simulation. Due to the hardness different, the diamond indenter can be assumed rigid when silicon thin film was test. However, the indenter¡¦s wear and compressive effects can not be ignored when diamond film were studied under nanoindentation simulation. The indentation parameter in the simulation includes substrate size, indentation velocity, peak hold time, system temperature, indentation depth, local void size, void position and vacancy rate. The results show that the hardness and elastic modulus of thin film may decrease significantly with considering the existence of local defect. The results also elucidated that the elastic modulus and hardness for perfect lattice structure thin films should be the upper bond value of the real bulk material.

Thesis (Ph.D.)--University of Central Florida, 2009. / Adviser: Viatcheslav Kokoouline. Includes bibliographical references (p. 138-149).

This dissertation has been motivated by the increasing application of sensing technologies in structural health monitoring. Many wireless sensor techniques exist for structural health monitoring while a challenge faced is the finite lifetime of batteries. The objective of this dissertation is to develop passive wireless technology to provide early warning of conditions that damage the structure. In this dissertation, sensing mechanism is proposed based on time and frequency domain characteristics of magneto-inductive (MI) waves. Experimental results are also presented to demonstrate the sensing mechanism. MI waves are predominantly magnetic waves that are supported in periodic arrays of magnetically coupled resonators and propagate within a narrow frequency band around the resonant frequency. The array is to be embedded in a structure and different types of transducers can be integrated for different sensing applications. With the onset of structure defect, the transducer introduces an impedance discontinuity that generates reflected MI waves along the array, which are monitored and processed by Smoothed Wigner-Ville distribution (WVD) to extract time-of-flight for frequency components in the narrow passband. The transmission and reflection coefficients of MI waves are also investigated based on the lumped-element circuit model of the array. Based on MI waves travel time, amplitude and group velocity, the position and severity of structure defect are decided. The sensing mechanisms for different distribution of defects are proposed. The validity of the sensing mechanism is examined in experiments. The guided wave testing is implemented in one-dimensional square-shaped printed spiral resonators with Q-factor of 161 at 13.6 MHz. It demonstrates that low MI waves propagation loss is achieved with value of 0.098 dB per element at mid-band with center-to-center distance of half an inch. A pitch-catch measurement system is built to capture traveling MI signal in resonant element and extract group velocity, and a pulse-echo measurement system is designed to monitor reflected MI signal and locate structure discontinuity. In both measurement systems, MI waves are excited with wide bandwidth voltage pulse, and a digitizer is attached to sense the MI signal in a specific resonant element circuit. A baseline signal is obtained from the healthy state to use as reference and comparison with the test case using pitch-catch system. The test signal subtracted from baseline signal infers the structure damage information with time and frequency domain characteristics. It can offer an effective method to estimate the structure discontinuity location, severity and type of damage. The experimental results are consistent with the theoretical predictions. At the end, future directions for the research to integrate with other technologies are suggested. / text

Defect-induced ferromagnetism is attracting intensive research interest. It not only challenges the traditional opinions about ferromagnetism, but also has some potential applications in spin-electronics. SiC is a new candidate for the investigation of defect-induced ferromagnetism after graphitic materials and oxides due to its high material purity and crystalline quality. In this thesis, we made a comprehensive investigation on the structural and magnetic properties of ion implanted and neutron irradiated SiC sample. In combination with X-ray absorption spectroscopy and first-principles calculations, we try to understand the mechanism in a microscopic picture. For neon or xenon ion implanted SiC, we identify a multi-magnetic-phase nature. The magnetization of SiC can be decomposed into paramagnetic, superparamagnetic and ferromagnetic contributions. The ferromagnetic contribution persists well above room temperature and exhibits a pronounced magnetic anisotropy. We qualitatively explain the magnetic properties as a result of the intrinsic clustering tendency of defects. By combining X-ray magnetic circular dichroism and first-principles calculations, we clarify that p electrons of the nearest-neighbor carbon atoms around divacancies are mainly responsible for the long-range ferromagnetic coupling. Thus, we provide a direct correlation between the collective magnetic phenomena and the specific electrons/orbitals. With the aim to verify if the defect-induced magnetization can be increased by orders of magnitude, i.e., if a sample containing defects through its bulk volume can persist ferromagnetic coupling, we applied neutron irradiation to introduce defects into SiC. Besides a weak ferromagnetic contribution, we observe a strong paramagnetism, scaling up with the neutron fluence. The ferromagnetic contribution induced by neutron irradiation only occurs in a narrow fluence window or after annealing. It seems non-realistic to make the bulk specimens ferromagnetic by introducing defects. Instead, we speculate that defect-induced ferromagnetism rather locally appears in particular regions, like surface/interface/grain boundaries. A comparable investigation on neutron irradiated graphite supports the same conclusion.

The application of popular image processing and classification algorithms, including agglomerative clustering and neural networks, is explored for the purpose of grouping semiconductor wafer defect map patterns. Challenges such as overlapping pattern separation, wafer rotation, and false data removal are examined and solutions proposed. After grouping, wafer processing history is used to automatically determine the most likely source of the issue. Results are provided that indicate these methods hold promise for wafer analysis applications. / text

Current metrology methods involve technicians viewing through a microscope, increasing the time, cost, and error rate in inspection. Developing an automated inspection system eliminates these difficulties. Shown in this work is a laser scanning microscope (LSM) design for an opto-electronic detection system (OEDS), based upon the concept that intensity differences related to pattern defects can be obtained from reflections off fused silica samples coated with photoresist (PR) or Aluminum. Development of this system for data collection and processing is discussed. Results show that 2.1 μm resolution of these defects is obtainable. Preliminary results for larger-array patterns through stitching processes are also shown. The second part of this work uses the concept of phase contrast edge detection. Looking at non-metallized patterns, one can use the property that phase changes induced by a refractive-index sensitive material can be seen with a multi-cell array, rendering the image visible by comparing the respective phases. A variety of defects and samples are shown. Extrapolating results to larger arrays is also discussed. Latent imaging, or imaging without development, is also evaluated. Future work in the areas of system commercialization, sample storage, and other mass-printing techniques are discussed.

Amelogenesis imperfecta (AI) is a genetically determined enamel defect characterized by genetic and clinical heterogeneity . The prevalence and incidence of AI were established in the county of Västerbotten, northern Sweden, in 3-19-yr-olds born 1963-79, as were the mode of inheritance and clinical manifestation of AI. The distribution of the inorganic component in the enamel of AI teeth was studied as well as the surface morphology and other morphological details, and the findings were correlated to genetic and clinical data. AI was diagnosed in 79 children and adolescents (index cases). The prevalence in the study population was 1.4: 1 000. The mean yearly incidence 1963-79 was 1.3:1 000. The inheritance patterns for AI were established in 78 index cases from 51 families. Pedigree and segregation analyses suggested autosomal dominant (AD) inheritance in 3 3 families, autosomal recessive (AR) in six families, and X- linked recessive in two families; in ten families only sporadic cases were found. In one of the families with an AD inheritance pattern, X-linked dominant was a possible alternative. Examination of the families of the 78 index cases revealed 107 new cases of AI. The hypoplastic form was seen in 72% of all diagnosed cases and the hypomineralization form in 28% of the cases. A further classification of the clinical manifestations led to the identification of eight clinical variants. In 3 3 of the 51 families the same clinical variant was found in all affected members. In eight families affected members were assigned to different clinical variants. In three families with an X-linked inheritance pattern for AI, the clinical manifestation differed between women and men due to lyo- nization. Among the remaining five families, with an AD inheritance pattern for AI, variants clinically characterized by hypoplasia as well as variants characterized by hypomineralization were found in three families; in the other two families the clinical manifestation varied within the same main form of AI, i.e. hypoplasia or hypomineralization. Hypoplasia as well as hypomineralization were observed microradiographically in the enamel of most of the examined teeth. These findings were supported by scanning electron microscopy (SEM). Both clinically and microradiographically as well as by SEM, similar variants of AI were found as AD and AR traits and/or among the sporadic cases. In the families with AI as an X-linked trait the genetic hypothesis was confirmed by the clinical, microradiographic and scanning electron microscopic findings. / <p>S. 1-46: sammanfattning, s. 47-134: 5 uppsatser</p> / digitalisering@umu