Magnetically coupled oscillators applicable to high-sensitivity mass detection

Microsystem Technologies - In this paper, a system of magnetically coupled oscillators consisting of a Π-shaped horizontal cantilever and a rectangular vertical cantilever with a frequency...     

Characteristics of sol-gel derived PZT thin films with lead oxide cover layers and lead titanate interlayers

The sol-gel derived PbZr_0.53Ti_0.47O₃ (PZT) films were fabricated on the bare Pt/Ti/SiO₂/Si substrates or the same substrates coated by the PbTiO₃ (PT) interlayers. The post-deposition annealing temperature and time were optimized when the PbO cover layers and PbO vapour-containing atmosphere were compared with each other and adopted as the method to diminish the lead-loss problem during the high-temperature post-deposition annealing. The X-ray diffraction patterns, microstructures, and electrical properties such as relative permittivity, _r, remanent polarization, P _r, and coercive electrical field, E _c, were investigated in relation to the annealing conditions. The PZT films deposited on the bare Pt/Ti/SiO₂/Si substrates under the PbO vapour-containing atmosphere showed better electrical properties. This indicates that the PbO vapour-containing atmosphere may be the better method of lead-loss-prevention to process the lead-containing films rather than the PbO cover layer method. The electrical characteristics of the PZT films, _r=1150, a dissipation factor of 0.039, P _r=26 C cm^–2, and E _c=40.5 kV cm^–1 were measured at 1 kHz. When PZT films were deposited on substrates coated by the PT layers, PZT-PT films with single perovskite phase were derived by post-deposition annealing at 500 °C for 1 h. However, the relative electrical properties are very poor, i.e. E _r=160, P _r=2.0 C cm^–2 and E _c=75 kVcm^–1. The optimum combination for preparing PZT-PT films is a 40 nm PbTiO₃ interlayer and annealing conditions of 6 h at 550 °C in a PbO vapour-containing atmosphere; the derived films exhibit electrical properties of E _r=885, P _r=21.5 C cm^–2 and E _c=64 kV cm^–1. The combination of inserting a PT interlayer and annealing in a PbO vapour-containing atmosphere can prevent the formation of electrical short paths. In this case, nearly pin-hole-free PZT films can be grown on the PT (interlayer) /Pt/Ti/SiO₂/Si substrates. It is believed that it is possible to prepare the PZT films with nano-scale uniformity, reproducible quality, which may be worth considering for commercial applications.     

Production of IL-6 by T cells from the femoral head of patients with rapidly destructive coxopathy (RDC)

We developed a method to improve the quantitative precision of FDG-PET scans in cancer patients. The total-lesion evaluation method generates a correlation coefficient (r) constrained Patlak parametric image of the lesion together with three calculated glucose metabolic indices: (a) the total-lesion metabolic index ("KT-tle", ml/min/lesion); (b) the total-lesion voxel index ("VT-tle", voxels/lesion); and (c) the global average metabolic index ("KV-tle", ml/min/voxel). METHODS: The glucose metabolic indices obtained from conventional region of interest (ROI) and multiplane evaluation were used as standards to evaluate the accuracy of the total-lesion evaluation method. Computer simulations and four patients with metastatic melanoma before and after chemotherapy were studied. RESULTS: Computer simulations showed that the total-lesion evaluation method has improved precision (% s.d. < 0.6%) and accuracy (approximately 10% error) compared with the conventional ROI method (% s.d. approximately 5%; approximately 25% error). The KT-tle and VT-tle indices from human FDG-PET studies using the total-lesion evaluation method showed excellent correlations with the corresponding values obtained from the conventional ROI methods and multiplane evaluation (r approximately 1.0) and CT lesion volume measurements. CONCLUSION: This method is a simple but reliable way to quantitatively monitor tumor FDG uptake. The method has several advantages over the conventional ROI method: (a) less sensitive to the ROI definition, (b) no need for image registration of serial scan data and (c) includes tumor volume changes in the global tumor metabolism.     

Molecular dynamics simulations of diffusion of submonolayer polar liquid lubricant films on solid surfaces

A fundamental understanding of the diffusion phenomena of submonolayer polar liquid films is important for achieving reliable lubrication between moving mechanical parts separated by a nanometer-sized gap. To acquire this understanding, we conducted molecular dynamics (MD) simulations of diffusion phenomena of submonolayer polar perfluoropolyether (PFPE) Zdol films on solid surfaces. To improve the accuracy of these simulations, we developed an all-atom model that includes hydrogen-bond potential and refined atomic charges for Zdol molecules and tested it through MD simulations of spreading of step-shaped submonolayer PFPE films. Our MD simulations reproduced the experimentally observed effects of polar end groups on the diffusion speed and molecular conformation of Zdol. We then conducted MD simulations of self-diffusion of submonolayer Zdol films; these simulations demonstrated that as the thickness of the submonolayer Zdol films decreases, molecular conformation becomes flatter and the self-diffusion coefficient decreases. These changes in molecular conformation partially explain our experimental finding that the spreading of step-shaped submonolayer polar PFPE films slows down with decreasing initial thickness.     

New pixel driving circuit using self‐discharging compensation method for high‐resolution OLED micro displays on a silicon backplane

A new 4T2C pixel circuit formed on a silicon substrate is proposed to realize a high‐resolution 7.8‐μm pixel pitch AMOLED microdisplay. In order to achieve high luminance uniformity, the pixel circuit compensates its Vth variation of the MOSFET for the driving transistor internally by using self‐discharging method. Also presented are 0.5‐in Quad‐VGA and 1.25‐in wide Quad‐XGA microdisplays with the proposed pixel circuit.     

Patient views of adverse events: comparisons of self-reported healthcare staff attitudes with disclosure of accident information

In the present paper, we report results of surveys in 2003 in Japan and Denmark about patients' views about adverse events, focusing on the actions of healthcare staff involved in a medical accident. Results show that patients were more likely to indicate negative expectations to a doctor's reactions after a medical accident when asked in general terms than when asked in relation to concrete case stories. When asked in general terms, 66% (47%) of Japanese (Danish) respondents expected that doctors sometimes hold back on providing information to patients about a medical accident, while 37% (7%) did so when asked about a concrete, mild-outcome case. We examine some possible reasons for the relatively high level of distrust of Japanese patients, and we discuss whether the seemingly lower level of disclosure in Japan than in Denmark and the negative stories in the Japanese press may have an impact. We also suggest some implications for introducing a patient-centred or customer-centred approach to risk management in healthcare and other domains.     

Low temperature hopping conduction in neutron transmutation doped isotopically enriched70Ge:Ga single crystals

The temperature dependence of variable range hopping resistivity in neutron transmutation doped (NTD) isotopically enriched⁷⁰Ge:Ga samples is reported. Five samples with compensation ratios K less than 0.001 and Ga concentrations between 3×10¹⁶ and 1.77×10¹⁷ cm^–3 were studied. All samples investigated show the ln T^–1/2 dependence in the temperature range below 1.5K. As thermistor materials NTD⁷⁰Ge:Ga samples are found to have more than factor of two higher sensitivity than commonly used natural NTD Ge in the temperature range between 0.2K and 1K. Our results are compared with theoretical predictions for variable range hopping conduction.     

Dielectric Dispersion of Polycrystalline Aluminum Nitride at Microwave Frequencies

Complex permittivity of polycrystalline AlN was measured over the frequency range 100 MHz to 13 GHz using reflection coefficient and cavity resonator methods. Dielectric relaxation peaks of loss tangent were observed in the frequency range 200 MHz to 3 GHz. The maximum value of loss tangent was ∼200 × 10⁻⁴. Relative permittivities decreased by ∼4% with increased frequency at the region of relaxation peaks. It was shown that these dispersion frequencies were inversely proportional to the grain sizes of AlN and independent of purities and processes. Model calculations for elastic vibration of a single-crystal grain of AlN were performed to investigate the origin of the dielectric dispersion due to piezoelectric effect. The calculated results of elastic sphere and 14-faced-polyhedron models showed a good quantitative agreement with the observed dispersion frequencies, which suggested that the dispersion was due to a piezoelectric vibration of a single grain of AlN ceramics at microwave frequencies.     

Further study on different dopings into PbWO4 single crystals to increase the scintillation light yield

Since we presented our preliminary result (Nucl. Instr. and Meth. A 486 (2002) 170) at SCINT2001, we have continued our efforts to increase the light yield (LY) of PbWO₄ scintillators by extending different dopings with an aim to find a possibility of using PbWO₄ successfully in Positron Emission Tomography (PET). Overall result obtained for single doping as well as double and tripple co-dopings are summarized, including decay characteristics and radiation hardness. The LY in non-doped PbWO₄ crystals with a size of 10×10×(20–30) mm³ is 25–35 photolectrons/MeV (phe/MeV) corresponding to 3–4% of the LY in BGO, when measured with a bialkali photomultiplier during a gate of 1 μs. The maximum LY increased to 49 phe/MeV for single doping with Mo⁶⁺, 80 phe/MeV for double co-doping of Mo⁶⁺+Sb⁵⁺, and 85 phe/MeV for tripple co-doping of Mo⁶⁺+Cd²⁺+Sb⁵⁺. The radiation hardness is larger than 10⁵ Gy for each of the samples co-doped with Mo⁶⁺+Sb⁵⁺ and Mo⁶⁺+Cd²⁺+Sb⁵⁺, while it is much poorer in PWO:Mo⁶⁺. In each of these co-doped samples, a medium-speed green emission in the microsecond range is created besides the fundamental fast (a few nanoseconds range) blue one, giving a peak at 500 nm in the radioluminescence spectrum similarly as in PWO:Mo⁶⁺.