The disruption of the blood-brain barrier (BBB) occurs after ischemic and hemorrhagic stroke and contributes to secondary brain damage. Matrix metalloproteinase-9 (MMP9) has been identified to be the main mediator of post-stroke BBB disruption. It is unknown whether deposition of heme/iron in the brain following stroke would affect MMP9 expression. In this study, I have demonstrated that heme/iron up-regulated MMP9 expression in rat astrocytes and that this upregulation was most likely due to reactive oxygen species (ROS) generated by heme/iron deposition on cells. ROS can activate AP-1 and NFκB signaling pathways which were responsible for increased MMP9 expression. Inhibiting AP-1 and NFκB decreased MMP9 expression. Heme/iron deposition also activated Nrf-2 and increased the expression of neuroprotective heme oxygenase-1. My study suggests that heme and iron deposition generates ROS and increases MMP9 expression through AP-1 and NFκB signaling pathways and that targeting these pathways or clearance of heme and iron may modulate MMP9 expression for reduced damage.

To fully exploit the strengths of La2Zr2O7 pyroclores and promote them as a next-generation thermal barrier coating (TBC), the improvements of their thermally insulating property and fracture toughness are studied in this thesis. A strong phonon scattering source, rattlers, is found in Y3+-doped La2Zr2O7 pyrochlores. Rattlers dramatically flatten k (thermal conductivity)-T curves, or even make k approach the amorphous limit. The presence of rattlers is strongly dependent on (1) oversized atomic cages that are formed in pyrochlores; and (2) the occupation of smaller guest ions in those oversized cages. To maximize the rattling effect, In3+/Sc3+ ions that are much smaller than Y3+ are introduced to the La2Zr2O7 lattice. As envisaged, the smaller ions in the oversized lattice voids make k glass-like at a much lower doping content. Nevertheless, they are still not effective in reducing the high temperature plateau kmin. Instead, oxygen vacancies are very effective in reducing kmin, because they generate an electrostatic repulsion force among cations surrounding them, resulting in stronger lattice anharmonicity and weaker bonds. The plateau kmin is reduced dramatically by the filling of the B-sites in La2Zr2O7 with a 21% larger (and 50% heavier) Ce4+ guest ion rather than a 96% heavier (but similar-sized) Hf4+ ion, suggesting that a large absolute size of substitutional atoms is more effective in reducing kmin than a heavy absolute mass. This is because: (1) kmin is proportional to (E/M)0.5 (where E is the elastic modulus and M is the average atomic mass); (2) a larger size of guest ions tends to produce a weaker ionic bond and consequently, a lower E; and (3) the changing extent of E by introducing larger guest ions is much greater than that of M induced by adding heavier ones. Lastly, the fracture toughness (KIc) has been increased by dispersing the tetragonal 3 mol% Y2O3-stabilized zirconia (t-3YSZ) particulates in the La2Zr2O7 (LZ) matrix. The tendency of the dispersive t-3YSZ second phases transforming to monoclinic (m) phases strongly depends on the volume fraction introduced. For samples made from equilibrium route, they are toughened by phase transformations within the dispersive t-3YSZ second phases and a crack shielding effect arising from the residual compressive stress within the LZ matrix. An anticipated increase of KIc from ferroelastic toughening together with the residual compressive stress toughening highlights a potential to improve coating durability by depositing t’-3YSZ/LZ composite TBCs by the non-equilibrium route.

Plasma actuators are electrical devices that generate a wall bounded jet without the use of any moving parts. For aerodynamic applications they can be used as flow control devices to delay separation and augment lift on a wing. The aim of this project is to initially develop a system capable of generating and sustaining a plasma that generates a wall bounded jet. The next step is to investigate the effect of varying the number and distribution of encapsulated electrodes in the dielectric layer. Finally the best case design is applied at the leading edge and flap shoulder of a NACA0015 aerofoil with a 20% flap. Utilising a transformer cascade, plasma has been generated for a variety of input voltages. In the quiescent environment of a Faraday cage the velocity flow field is recorded using particle image velocimetry (PIV). Through understanding of the mechanisms involved in producing the wall jet and the importance of the encapsulated electrode a novel actuator design was investigated. The actuator design distributes the encapsulated electrode throughout the dielectric layer. The experiments have shown that actuators with shallow initial encapsulated electrodes induce velocities greater than the baseline case at the same voltage. Actuators with a deep initial electrode are able to induce the highest velocities as they can operate at higher voltages without breakdown of the dielectric. The best actuator case is applied to the aerofoil for Reynolds numbers of 1:97x10⁵, 2:63x10⁵ and 3:29x10⁵. The lift and drag are recorded using pressure measurements around the aerofoil surface and across the aerofoil's wake. PIV is utilised to visualise the flow field. The trailing edge actuator produces a step increase in lift for pre-stall angles of attack and delays stall by 1° at Re = 1:97x10⁵. The leading edge actuator has limited impact on the flow for the no flap deflection case due to the actuator location. As the flap deflection increases the leading edge actuator is able to influence the flow. Repositioning of the leading edge actuator has the ability to reattach the flow around the fore portion of the aerofoil at a post stall angle of alpha = 18°.

>Magister Scientiae - MSc / In South Africa, water pollution problems have continued to increase due to increasing anthropogenic activities. The increasing number of organic contaminants in various water sources can be attributed to industrial development, population growth and agricultural run- off. These activities have impacted negatively on the availability and accessibility to sustainable clean water resources, exposing citizens to water borne diseases such as cholera, diarrhoea and typhoid fever; commonly reported among children. Advanced oxidation technologies such as dielectric barrier electrohydraulic discharge (EHD), also referred to as dielectric barrier discharge (DBD), have the ability to decompose persistent organics and eliminate microbes. DBD offers advantages such as efficiency, energy saving, rapid processing, use of few or no chemicals, and non-destructive impact on the ecosystem. The system is also capable of generating ozone, hydrogen peroxide, singlet oxygen, superoxide radicals, hydroxyl radicals and other active species. The combination of these reactive species has been reported to degrade biological and chemical pollutants rapidly and efficiently. In this study, the DBD system was optimized by investigating the effect of physico-chemical, electrical parameters and reactor configurations on Methylene Blue (MB) decolouration efficiency. The physico-chemical parameters included MB concentration, solution pH and conductivity, solution volume, NaCl electrolyte concentration in the electrode compartment and air flow rate. As for electrical parameters, the effects of voltage, electrode type and size on MB decolouration efficiency were studied. The effect of the aforementioned parameters on MB decolouration efficiency was assessed by varying one parameter at a time. The following physico-chemical parameters: time (from 0 - 60 minutes), pH (2.5 - 10.5), solution conductivity (5 - 20 mS/cm), MB concentration (0.5 – 10 mg/L), solution volume (500 – 2000 mL), NaCl electrode electrolyte concentration (10 – 50 g/L) and air flow rate (2– 4 L/min) were varied in their respective ranges under the applied experimental conditions: reactor air gap 2 mm, solution volume 1500 mL, NaCl electrolyte concentration of 50 g/L in the electrode compartment, voltage 25 V (7.8 kV), airflow rate 3 L/min, 0.5 mm silver electrode and a running time of 60 minutes. As for electrical parameters, voltage (from 20 - 25 V), electrode type (copper, silver and stainless steel) and electrode diameter (0.5 – 1.5 mm) were also altered individually at the applied experimental conditions. The reactor air gap was varied from 2 to 6 mm. At the same experimental conditions, the free reactive species generated mainly H2O2 and O3, were detected and quantified using the Eisenberg and indigo methods, respectively. The optimum physico-chemical parameters were found to be MB concentration 5 mg/L, concentration of NaCl electrolyte used in the central compartment of the DBD reactor 50 g/L, solution pH 2.5, solution conductivity 10 mS/cm, air flow rate 3 L/min, solution volume 1500 mL and an optimum contact time of 30 minutes. The optimum electrical parameters were found to be: applied voltage 25 and 1.5 mm silver electrode. The following parameters MB concentration, solution conductivity and pH, applied voltage and reactor configuration significantly affected MB decolouration efficiency compared to parameters such as solution volume, the inlet air flow rate, electrode type and size and NaCl electrolyte concentration in the electrode compartment, which were less effective in enhancing MB decolouration. Moreover, for all DBD experiments performed at the applied experimental conditions, complete decolouration of MB was achieved in the first 30 minutes. However, trends between the optimized parameters and MB decolouration efficiency were mostly observed after 10 minutes. The optimized DBD system reduced the treatment time from 30 to 20 minutes without any chemical additives. Moreover, at 5 mg/L MB under the applied optimum conditions, it was proved that besides 99% of MB decolouration reached after 60 minutes, 53% of total organic carbon (TOC) removal was also achieved. The chemical oxygen demand (COD) characterizing MB toxicity was less than 5 mg/L before as well as after the DBD experiment. After 10 minutes of experiment under the following conditions: Applied voltage 25 V, MB concentration 5 mg/L, solution pH (in between 6.04 and 6.64), solution volume 1500 mL, air flow rate 3 L/min, 0.5 mm silver electrode and a contact time of 60 minutes, about 3.73 x 10-5 mol/L H2O2 was produced which decreased to 2.93 x 10-5 mol/L 10 minutes later, while O3 concentration was initially very low and could not be detected. However, 0.5 mol/L of O3 was detected after 20 minutes of operating time, thereafter, H2O2 concentration decreased continuously with time while that of O3 fluctuated as the treatment time increased. Likewise, the energy density for the production of free reactive species reached 0.87 g/ kWh in the first 10 minutes due to the presence of chromophoric functional groups such as =N+(CH3)2 in MB structure that had to be destroyed. Thereafter, the energy consumption decreased progressively to zero with an increase in treatment time due to the destruction of =N+(CH3)2 groups in MB structure with time. The correlation between the rise in the of H2O2 concentration and energy density after 10 minutes was probably due to dissociation of OH- OH bonds in H2O2 by UV light to yield OH radicals which unselectively may have attacked MB dye. Thus, MB decomposition in the current DBD reactor was mostly initiated by H2O2 and O3. The irradiation of H2O2 by UV light generated in the DBD system was found to accelerate dye decomposition in the first 30 minutes of the experiment. The UV-vis analysis of treated MB samples confirmed that the complete decolouration of MB achieved in the first 30 minutes was due to the destruction of the chromophoric [=N+(CH3)2] group in Methylene blue structure, while the FT-IR confirmed the presence of traces of various functional groups such as C=C, C=O, C=N, NH, NH3, NO2, etc. characteristics of carboxylic acids, amines, amides, nitrogen based compounds (salts), aliphatic and unsaturated by-products remaining in the bulk solution after treatment. The salts analysis after treatment showed that 16 mg/L of nitrates and nitrites and 1.1mg/L of sulphates mainly originating from air and MB decomposition were present in the treated samples. The EHD/DBD system used in this study offers an approach to partially treat water/wastewaters and its optimization was able to significantly enhance the decomposition of the target MB dye as indicated by the reduction of total organic carbon (TOC) from 8.3 mg/L to 3.9 mg/L. Compared to previous research, this study successfully optimised a complete double cylindrical dielectric barrier discharge (DBD) reactor at ambient condition without any chemical additives.

Disruption of the blood-brain barrier (BBB) is hypothesized to play an important role in the disease biology of schizophrenia (SZ). Brain microvascular endothelial cells (BMECs) have paracellular and transcellular proteins, transporters, as well as important extracellular matrix proteins, which collectively contribute to maintaining proper BBB function. While previous studies have provided some insights into the role of the BBB in SZ pathophysiology, there is a significant gap in our understanding of the cellular-molecular underpinnings of its major component, BMECs. Human induced pluripotent stem cells (hiPSCs) provide an exciting new avenue for exploring the role of BMECs in SZ. We hypothesize that BMECs have intrinsic deficits that lead to BBB dysfunction in SZ. In this study, we first aimed to test whether the existing hiPSC-derived BMEC protocols work with our patient-specific hiPSC samples. Secondly, we sought to investigate any potential deficits between BMECs derived from healthy control (HC) and SZ subjects. We successfully adapted the established protocol and confirmed the identity of these hiPSC-derived BMECs with relevant cell markers such as CLDN5, OCLN, TJP1, PECAM1, and SLC2A1. We also evaluate barrier function by measuring trans-endothelial electrical resistance (TEER) and efflux transporters activity of ABCB1 and ABCC1. We observed evidence of poor cellular adhesion and disrupted tight junctions in a subset of SZ hiPSC-derived BMECs, where approximately 70% of them demonstrated extensive BBB disruption (reduced TEER). These findings suggest that there may be cell-autonomous disease-specific deficits in BMECs in SZ that result in BBB dysfunction. / 2022-06-07T00:00:00Z

In this work, the possibility of Cu electrodeposition on Ru-Ta alloy thin films is explored. Ru and Ta were sputter deposited on Si substrate with different composition verified by RBS. Four point probe, XRD, TEM and AFM were used to study the properties of Ru-Ta thin films such as sheet resistance, crystallinity, grain size, etc. Cyclic voltammetry is used to study the Cu electrodeposition characteristics on Ru-Ta after various surface pretreatments. The results provide insights on the removal of Ta oxide such that it enables better Cu nucleation and adhesion. Bimetallic corrosion of Cu on modified Ru-Ta surface was studied in CMP related chemicals. In Cu interconnect fabrication process, the making of trenches and vias on low-k dielectric films involves the application of fluorocarbon plasma etch gases. Cu microdots deposited on Ru and Ta substrate were treated by fluorocarbon plasma etch gases such as CF4, CF4+O2, CH2F2, C4F8 and SF6 and investigated by using x-ray photoelectron spectroscopy, contact angle measurement and electrochemical techniques. Micropattern corrosion screening technique was used to measure the corrosion rate of plasma treated Cu. XPS results revealed different surface chemistry on Cu after treating with plasma etching. The fluorine/carbon ratio of the etching gases results in different extent of fluorocarbon polymer residues and affects the cleaning efficiency and Cu corrosion trends.

京都大学 / 新制・課程博士 / 博士(社会健康医学) / 甲第23119号 / 社医博第115号 / 新制||社医||11(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 近藤 尚己, 教授 万代 昌紀, 教授 川上 浩司 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DFAM

Barrier options are the most popular and traded derivatives in the financial market because of their lower prices. Many studies have been conducted to develop the methods of pricing barrier options. Barrier option prices can be calculated using the classical binomial tree method, but it is time-consuming when we have a large number of time periods. Muroi and Yamada have developed a new fast algorithm to obtain the prices of barrier options by using the spectral expansion approach. We implement and check this algorithm by doing more extensive numerical experimental studies and showing that the same prices calculated using the binomial tree method can also be obtained using the spectral binomial tree approach with a higher computational speed.

The goal of my master‘s thesis is to project a municipality with an attached library in the town Leopoldov. The municipality building has two aboveground floors and the library is designed as a single-floor structure. Both are designed to be barrier-free. The construction system is made out of limestone-sand blocks. The ceilings are mostly made out of prestressed ceiling panels, except for the first floor of the municipality, where the prestressed panel ceiling is combined with monolithic ceiling plates made out of reinforced concrete. The roof of the library is projected as a green roof with a terrace and the municipality has a flat deck roof with river gravel.

This diploma thesis is focused on preparation and characterization of parylene C barrier properties. The layers were prepared by chemical vapour deposition (CVD). The interest in characterization of those layers is huge mainly because of their possible use in museology for the protection of the museum archives against the corrosion. Chlorinated dimer of para-xylylene was used as a precursor. Polypropylene foils, metal sheets and silica wafers were used as tested substrates for thin film preparation. Polypropylene foils were used for oxygen transmission rate measurements, metal sheets were used for corrosion tests and silica wafers were used for Fourier transform infrared spectroscopy (FTIR), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and stylus profilometry.