BACKGROUND: Meningiomas are the most common primary benign brain tumors in adults. Given the extended life expectancy of most meningiomas, consideration of quality of life (QOL) is important when selecting the optimal management strategy. There is currently a dearth of meningioma-specific QOL tools in the literature. OBJECTIVE: In this systematic review, we analyze the prevailing themes and propose toward building a meningioma-specific QOL assessment tool. METHODS: A systematic search was conducted, and only original studies based on adult patients were considered. QOL tools used in the various studies were analyzed for identification of prevailing themes in the qualitative analysis. The quality of the studies was also assessed. RESULTS: Sixteen articles met all inclusion criteria. Fifteen different QOL assessment tools assessed social and physical functioning, psychological, and emotional well-being. Patient perceptions and support networks had a major impact on QOL scores. Surgery negatively affected social functioning in younger patients, while radiation therapy had a variable impact. Any intervention appeared to have a greater negative impact on physical functioning compared to observation. CONCLUSION: Younger patients with meningiomas appear to be more vulnerable within social and physical functioning domains. All of these findings must be interpreted with great caution due to great clinical heterogeneity, limited generalizability, and risk of bias. For meningioma patients, the ideal QOL questionnaire would present outcomes that can be easily measured, presented, and compared across studies. Existing scales can be the foundation upon which a comprehensive, standard, and simple meningioma-specific survey can be prospectively developed and validated.

Customer requirements and vision in aerospace dictate that the next generation of civil transport aircraft should have a strong emphasis on increased safety, reduced environmental impact and reduced cost without sacrificing performance. In this context, the School of Mechanical and Aerospace Engineering at the Queen’s University of Belfast and Bombardier have, in recent years, been conducting research into some of the key aerodynamic technologies for the next generation of aircraft engine nacelles. Investigations have been performed into anti-icing technology, efficient thrust reversal, engine fire zone safety, life cycle cost and integration of the foregoing with other considerations in engine and aircraft design. A unique correlation for heat transfer in an anti-icing system has been developed. The effect of normal vibration on heat transfer in such systems has been found to be negligible. It has been shown that carefully designed natural blockage thrust reversers without a cascade can reduce aircraft weight with only a small sacrifice in the reversed thrust. A good understanding of the pressure relief doors and techniques to improve the performance of such doors have been developed. Trade off studies between aerodynamics, manufacturing and assembly of engine nacelles have shown the potential for a significant reduction in life cycle cost.

Anodic oxides of SixGe1−x (0 ≤ x ≤ 1 ) alloys have been made by plasma assisted oxidation in a microwave frequency (2.45 GHz) reactor working in the constant current bias mode. Oxide films ∼15 – 40 nm (depending upon the Ge concentration) were obtained in 10 minutes without a temperature rise of the substrate of more than 100 °C. Detailed infrared absorption studies of the oxides enabled the Si-O-Si, Ge-O-Ge and Si-O-Ge vibrational modes to be identified, the strongest being at 1056, 858 and 1000 cm−1 respectively. These modes are associated with the O asymmetric stretch, their values are at lower wavenumbers than in bulk oxides due partly to ultraviolet radiation induced structural modification and partly to thin film optic effects. A statistical model for the different bonds present in SixGe1−xO2, when used to simulate the infrared spectrum does not predict the experimentally observed form, the Ge-O-Ge peak is in general too intense in the experimental spectrum. Auger electron spectroscopy profiling of the SixGe1−x oxides suggests that there is a build-up of Ge close to the surface/oxide interface so that when combined with the infrared data, we conclude that there is a GeO2 rich region at the surface/oxide interface. The oxide is, however, globally stoichiometric. Electrical measurements (C(V) and interface state density) were begun on metal-oxide-semiconductor (MOS) capacitors for Si1−xGex. oxides over the range of concentrations 0 ≤ x ≤ 1. Only Si1−xGex oxides with x≤0.15 appear to yield satisfactory MOS capacitor curves.

Controlled oxidation of polycrystalline and single crystal silicon has been carried out at temperatures < 100 °C using microwave excited, plasma assisted anodisation. Oxide thicknesses up to 30 nm have been obtained in times ∼ 15 minutes. The growth kinetics are similar for both types of Si. The results of infrared absorption measurements clearly indicate that the anodic oxides have a network structure significantly different to that of high temperature, thermally grown oxides and this is partly due to ultra-violet radiation present in the plasma during growth. Electrical measurements (CV, IV) are underway on simple MOS capacitors. The results indicate that the plasma oxides have acceptable levels of fixed oxide charge but that the breakdown electric fields are presently low. Preliminary data suggests that these very low temperature oxides are suitable for TFT applications though some technical problems need to be addressed. Given these reservations the processing of large area flat panel displays using this type of plasma assisted oxidation is perfectly feasible.

In this work we show that annealing of silicon/silicon‐dioxide/silicon structures in forming gas (N2:H2; 95:5) above 500°C leads to spontaneous incorporation of mobile H+ ions in the buried SiO2 layer. We demonstrate that, unlike the alkali ions feared as killer contaminants in the early days, the space charge distribution of these mobile protons within the buried oxide layer can be very well controlled and easily rearranged with relatively high speed at room temperature. The hysteresis in the flat band voltage shift provides a unique vehicle to study proton kinetics in silicon dioxide thin films. It is further shown how this effect has great potential as the basis for a reliable nonvolatile FET memory device that is expected to be competitive with state‐of‐the‐art Si‐based memory technologies. The power of this novel device is its simplicity; it requires few processing steps, all of which are standard in Si integrated‐circuit fabrication.

We have performed electron spin resonance and electrical measurements on SiO2/Si structures subjected to anneals in 5% H2/N2 or 5% D2/N2 gases and subsequently injected with electrons using corona ions and ultra‐violet radiation. Threshold voltage and transconductance measurements have also been made on 0.25 μm metal‐oxide‐semiconductor transistors subjected to 400 °C anneals in the same gases and subsequently aged by hot electron injection. The electrical data on SiO2/Si structures indicates that the density of interface states increases as a result of electron injection but that there are only minor differences between H and D passivated interfaces. The data on Pb, trivalent Si dangling bond, centers at the same interfaces observed by electron spin resonance is insufficiently accurate to enable us to observe any significant differences. The hot electron injection experiments on transistors, consistent with other authors, indicate that, for the limited number of measurements we have made, the transistor ageing resulting from the generation of interface states is significantly reduced for devices annealed in the D containing gas as compared to those annealed in the H containing gas. The origins of some potential differences in annealing behaviour between the SiO2/Si structures and the 0.25 μm transistors are suggested.

High-temperature post-oxidation annealing of poly-Si/SiO2/Si structures such as metal-oxidesemiconductor capacitors and metal-oxide-semiconductor field effect transistors is known to result in enhanced radiation sensitivity, increased 1/f noise, and low field breakdown. We have studied the origins of these effects from a spectroscopic standpoint using electron paramagnetic resonance (EPR) and atomic force microscopy. One result of high temperature annealing is the generation of three types of paramagnetic defect centers, two of which are associated with the oxide close to the Si/SiO2 interface (oxygen-vacancy centers) and the third with the bulk Si substrate (oxygen-related donors). In all three cases the origin of the defects may be attributed to out-diffusion of O from the SiO2 network into the Si substrate with associated reduction of the oxide. We present a straightforward model for the interfacial region which assumes the driving force for O out-diffusion is the chemical potential difference of the O in the two phases (SiO2 and the Si substrate). Experimental evidence is provided to show that enhanced hole trapping and interface-trap and border-trap generation in irradiated high-temperature annealed Si/SiO2/Si systems are all related either directly, or indirectly, to the presence of oxygen vacancies.

Degradation of 430 nra thick SiO2 layers in Si/SiO2/Si structures which results from high temperature annealing (1320°C) has been studied using electron spin resonance, infra-red absorption spectroscopy and refractive index measurements. Large numbers of oxygen-vacancies are found in a region ≤ 100 nm from each Si/SiO2 interface. Two types of paramagnetic defects are observed following γ or X-irradiation or hole injection. The 1106 cm−l infra-red absorption associated with O interstitials in the Si substrate is found to increase with annealing time. The infra-red and spin resonance observations can be explained qualitatively and quantitatively in terms of a model in which oxygen atoms are gettered from the oxide into the under or overlying Si, the driving force being the increased O solubility limit associated with the anneal temperature.

An electron spin resonance study has been carried out on a-SiO2 films deposited from SiH4 and N2O gases using UV lamp induced chemical vapour deposition. Deposition pressures have been varied from 5 torr to 30 torr whilst the substrate temperature was maintained at 240°C. Bridging nitrogen (O3≡Si-N-Si≡O3) and oxygen-vacancy center defects are observed in small quantities (≈ 1016cm−3) whilst over coordinated N defects are observed in concentrations up to 1018 cm−3 dependent upon the deposition pressure. The concentration of these defects can be dramatically reduced either by depositing the a-SiO2 at high pressures (≈ 30 torr) or by post-deposition annealing at ≈ 600°C. Comparison with data on films produced by plasma enhanced chemical vapour deposition demonstrates that the mode of incorporation of nitrogen into the network depends critically upon the chemical species in the deposition reactor.

Ultraviolet radiation has been used to anneal out extrinsic defects in several types of deposited a-SiO2 films. The UV light was obtained from a new krypton UV-VIS-IR lamp with a spectral range of 170 nm <λ<3μ This “cold” annealing was performed on a-SiO2 films, with various thicknesses up to 400 nm. The films were deposited by various techniques, ultraviolet induced chemical vapour deposition (UVCVD), plasma enhanced vapour deposition (PECVD) and spin-on-glass (SOG). Fourier Transform Infra-Red spectroscopy (FTIR) and Electron Spin Resonance (ESR) were used to characterize the effect of the radiation. In the case of UVCVD and SOG a-SiO2 films, it is shown that the UV radiation removes the Si-H bonds and reduces significantly the amount of C-H and C-H3 groups. In both these films, an important reduction in the amount of adsorbed water and Si-OH groups is observed, together with an increase in the number of Si-O bonds. In PECVD films made with tetraethylorthosilicate (TEOS) vapour and O2 as precursor gases, we find evidence for an important reduction in the amount of C and the number of Cn Hy related defects. The UV treatment is effective even at temperatures as low as 100 °C, which suggests that it could constitute a much needed low temperature annealing step.

Silicon dioxide films have been deposited using a microwave plasma of (SiH4 + O2) excited by distributed electron cyclotron resonance. The ratio of flow rates of the reactive gas was (O2: SiH4) = 7 and no intentional substrate heating was used. The effect of ion energy during deposition, in the 10 — 150 eV range, has been studied through refractive index, infrared absorption bands, chemical etch rate and electrical measurements. It is found that for an ion energy > 50 eV, many of the film characteristics are close to those of thermal SiO2.

Amorphous SiO2 films have been deposited by plasma enhanced chemical vapor deposition (N2O:SiH4 flow rate ratio of 40:1) then 60Co gamma irradiated. We observe paramagnetic defects similar to oxygen vacancy centers which are created at least 100 times more efficiently in as-deposited oxide than in the same oxide annealed for 1 hr in Ar at 950°C. Positive fixed oxide charge creation in samples irradiated in the unbiased mode has a fractional yield of 0.018 defects per electron-hole pair. No enhancement of the positive fixed oxide charge creation is observed when comparing as-deposited and annealed films suggesting that the paramagnetic and electric defects do not have the same physical origin. Comments are made about the potential hazards of using such deposited oxide near a semiconductor surface where surface inversion may occur.