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[en] Brief review of development of insights into heterogenous structure of the glass is given. Contradictory results of direct structural investigation methods are compared. Development of fundamental researches of glass-like state and analysis of some contradictory experimental data on the structure of borate glasses permit to contemplate the ways for the further investigations
[en] A surface dielectric barrier discharge configuration with two identical high voltage electrodes is investigated in air at atmospheric pressure. Synchronized breakdown of streamers on both electrodes is evidenced by statistical study. The light emitted by plasma filament on one electrode can trigger the breakdown of streamers on the other electrode. The role of photodesorption of negative charges deposited on the Pyrex dielectric barrier is responsible for these self-synchronized breakdowns. The binding energy of negative charges photodesorbed is estimated to be lower than 3.5 eV.
[en] Output voltage drifting was observed in MEMS gyroscopes. Other than the quadrature error, frequency mismatch and quality factor, the dielectric parasitic charge was thought to be a major determinant. We studied the mechanism and variation of the parasitic charge in the MEMS gyroscopes, and analyzed the effect of the parasitic charge on the output stability. This phenomenon was extremely obvious in the Pyrex encapsulated MEMS gyroscopes. Due to the DC voltage required for the electrostatic actuation, the parasitic charge in the dielectric layer would accumulate and induce a residual voltage. This voltage had an impact on the resonant frequency of the gyroscopes, so as to affect the output stability. The theoretical studies were also confirmed by our experimental results. It was shown that the parasitic charge was harmful to the output stability of MEMS gyroscopes. (paper)
[en] The surface recombination probability of oxygen atoms as a function of wall temperature is studied by using a double pulse discharge technique. The main discharge pulse dissociates molecular oxygen and the second pulse, shorter than the main one, excites atoms during the stationary afterglow. The recombination probability is determined from the atomic oxygen density decay during the stationary afterglow of the main pulse (MP). The oxygen atoms are detected by time-resolved optical emission spectroscopy. In order to correlate the oxygen emission lines with the oxygen atom density, argon is used as an actinometer. To scan the whole afterglow of the main discharge pulse, the delay of the probe pulse is uniformly increased in every period following the MP. The evolution of the relative O atom density is deduced from the O emission lines at 777 and 844 nm and from the Ar actinometry line at 750 nm. The wall recombination probability γ on a Pyrex surface ranges from 4.0 x 10-4 to 1.6 x 10-2 for wall temperatures from 77 to 460 K
[en] Plasma diagnostics were carried out in a theta-pinch device to investigate the applicability for plasma-material interaction under fusion-like conditions. A series of triple probe diagnostics show that the plasma is sustained for approximately 80 (micro)s at each pulse, with 3.0 (10)21 m-3 plasma density and up to 40 eV electron temperature when a 32 (micro)F main capacitor is discharged at 20 kV. In order to increase plasma density and temperature, an RF antenna is installed near one end of a Pyrex tube and a 50 (micro)F preionization capacitor is connected to an electrode placed at the same end as the antenna. In this configuration, several time delays between the main and preionization capacitors are tested. When the preionization capacitor was triggered 45 (micro)s before the main bank discharge, it resulted in high energetic plasma being obtained with a few density spikes at 1022 m-3 and electron temperature around 100 eV.
[en] The experimental Hugoniot data obtained by Mcqueen et al. show that there is a plateau on D-U plane. Authors think this is a first order phase transition from one solid to another solid which results in a more closely packed structure and decreased compressibility. The entropy change is calculated on the basis of Gibbs equlibrium conditions, using the equation of state for low pressures. The entropy change is negative, which means that this phase transition is a exothermic process. Then the equation of state for phase transition region is achieved, where the cold pressure is constant and the energy includes the effect of the phase transition entropy. The calculated Hugoniot using the above equation of state is in agreement with experimental Hugoniot presented by Mcqueen et al
[en] Cells regulate their behavior in response to mechanical strains. Cell cultures to study mechanotransuction are typically cm"2 in area, far too large to monitor single cell response. We have developed an array of dielectric elastomer microactuators as a tool to study mechanotransduction of individual cells. The array consists of 72 100 µm × 200 µm electroactive polymer actuators which expand uniaxially when a voltage is applied. Single cells will be attached on each actuator to study their response to periodic mechanical strains. The device is fabricated by patterning compliant microelectrodes on both sides of a 30 µm thick polydimethylsiloxane membrane, which is bonded to a Pyrex chip with 200 µm wide trenches. Low-energy metal ion implantation is used to make stretchable electrodes and we demonstrate here the successful miniaturization of such ion-implanted electrodes. The top electrode covers the full membrane area, while the bottom electrodes are 100 µm wide parallel lines, perpendicular to the trenches. Applying a voltage between the top and bottom electrodes leads to uniaxial expansion of the membrane at the intersection of the bottom electrodes and the trenches. To characterize the in-plane strain, an array of 4 µm diameter aluminum dots is deposited on each actuator. The position of each dot is tracked, allowing displacement and strain profiles to be measured as a function of voltage. The uniaxial strain reaches 4.7% at 2.9 kV with a 0.2 s response time, sufficient to stimulate most cells with relevant biological strains and frequencies. (paper)
[en] We present a detailed experimental and theoretical study of edge enhancement in optically pumped Rb vapor in coated cylindrical pyrex glass cells. The Zeeman polarization of Rb atoms is produced and probed in the vicinity (∼10-4 cm) of the cell surface by evanescent pump and probe beams. Spin-polarized Rb atoms diffuse throughout the cell in the presence of magnetic field gradients. In the present experiment the edge enhanced signal from the back surface of the cell is suppressed compared to that from the front surface, due to the fact that polarization is probed by the evanescent wave at the front surface only. The observed magnetic resonance line shape is reproduced quantitatively by a theoretical model and yields information about the dwell time and relaxation probability of Rb atoms on Pyrex glass surfaces coated with antirelaxation coatings.