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991.
Jingkuang Chen Wise K.D. Hetke J.F. Bledsoe S.C. Jr. 《IEEE transactions on bio-medical engineering》1997,44(8):760-769
A bulk-micromachined multichannel silicon probe capable of selectively delivering chemicals at the cellular level as well as electrically recording from and stimulating neurons in vivo has been developed. The process buries multiple flow channels in the probe substrate, resulting in a hollow-core device, Microchannel formation requires only one mask in addition to those normally used for probe fabrication and is compatible with on-chip signal-processing circuitry. Flow in these microchannels has been studied theoretically and experimentally. For an effective channel diameter of 10 μm, a channel length of 4 mm, and water as the injected fluid, the flow velocity at 11 torr is about 1.3 mm/s, delivering 100 pl in 1 s. Intermixing of chemicals, with the tissue fluid due to natural diffusion through the outlet orifice becomes significant for dwell times in excess of about 30 min, and a shutter is proposed for chronic use. The probe has been used for acute monitoring of the neural responses to various chemical stimuli in guinea pig superior and inferior colliculus 相似文献
992.
Nanoindentor techniques have been used to obtain the values of hardness and elastic modulus of α-Al2O3 polycrystalline implanted
with metallic species at room temperature with 170 keV, doses ranging from 2×1016 to 2×1017 ions cm-2. After implantation,
annealing was performed in the temperature range 600–1400°C. An attempt has been made to correlate the mechanical property
modifications with physico-chemical analysis. Elastic and plastic properties of the implanted layers, of about 100 nm thickness,
have been characterized by microprobe investigation. This has indicated that certain fluences and thermal annealing temperatures
are favourable for the improvement of mechanical properties.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
993.
Full-wave solutions to the problem of radiation by open-ended rectangular waveguides (OEG) are presented. The radiation problem is formulated in terms of an electric field integral equation (EFIE). The EFIE is solved using the method of moments for three OEG antennas covering the frequency range from 200 to 750 MHz. Results for the near-zone gains as a function of both frequency and distance from the OEG aperture are presented. Estimates for uncertainties in the calculated gain are also given 相似文献
994.
Tungsten oxide and molybdenum doped tungsten oxide electrochromic films have been electrochemically prepared from a metal peroxide bath and experimentally tested. They were characterized by electrical and optical methods, using cyclic voltammograms and calculating the charge capacity as a function of the number of deposition cycles.The color of the electrochromic WO3 film is strongly altered by doping it with molybdenum. Electrochromic W---Mo oxide films were fabricated by adding different percentages of molybdenum to tungsten oxide, ranging from 0.5% to 7% weight of deposition solution. Normal optical transmittance was also measured and evidence is given of different behavior if the switching for oxidation and reduction cycle, so that coloration occurs in a shorter time than the bleaching. The time constant of the process tends to increase as a function of the molybdenum oxide doping concentration. 相似文献
995.
Using time-of-flight technique between 100 K and 700 K a nearly constant IC modulation parameter is found. It depends only weakly on crystal composition. The intensity of the first-and second-order satellites decreases with temperature and at 700 K it is nearly disappeared. These facts are discussed with a view to the anti-phase domain model. 相似文献
996.
F. Cœuret E. Oliveira Vilar E. Bezerra Cavalcanti 《Journal of Applied Electrochemistry》2002,32(10):1175-1182
The paper deals with carbon fibre cloth electrodes, employed in the fabrication of composite materials. The electrical conductivity of single bundles, groups of bundles and cloth is studied. Ohm's law applies to the electrical conduction in the direction of the fibre length, but bundle conductivity decreases with the number of fibres in the bundle. Electrochemical mass transfer between a flowing electrolyte and a cloth arranged as a flow-through or a flow-by porous electrode indicates the existence of double porosity in the material. Due to double porosity, only the external surface of the cloth works as an electrode. This finding shows that the material is not suitable for such an application. 相似文献
997.
This paper describes a new write/erase method for flash memory to improve the read disturb characteristics by means of drastically reducing the stress leakage current in the tunnel oxide. This new write/erase operation method is based on the newly discovered three decay characteristics of the stress leakage current. The features of the proposed write/erase method are as follows: 1) the polarity of the additional pulse after applying write/erase pulse is the same as that of the control gate voltage in the read operation; 2) the voltage of the additional pulse is higher than that of a control gate in a read operation, and lower than that of a control gate in a write operation; and 3) an additional pulse is applied to the control gate just after a completion of the write/erase operation. With the proposed write/erase method, the degradation of the read disturb life time after 106 write/erase cycles can be drastically reduced by 50% in comparison with the conventional bipolarity write/erase method used for NAND type flash memory. Furthermore, the degradation can he drastically reduced by 90% in comparison with the conventional unipolarity write/erase method fur NOR-, AND-, and DINOR-type flash memory. This proposed write/erase operation method has superior potential for applications to 256 Mb flash memories and beyond 相似文献
998.
N. Murayama M. Awano Y. Kodama S. Sakaguchi F. Wakai 《Journal of Materials Science》1992,27(13):3642-3644
Bi0.85Pb0.15Sr0.8CaCu1.4O
y
superconductor was quenched to room temperature after annealing at several temperatures in air. From the initial magnetization curve measurement for the annealed samples, it was found that the volume fraction of superconducting phases of the sample annealed at 650°C greatly decreased. TEM observation revealed that a second phase often appeared in the grain-boundary region for the sample annealed at 700°C. The second phase was identified as Bi1Pb2Sr2.6Ca1.6O
y
by energy dispersive spectroscopy. 相似文献
999.
T.J.L. McComb A.B. Rimmer M.L.B. Rodgers K.E. Turver A.F. Vickers 《Cold Regions Science and Technology》1992,20(3)
A mathematical model for predicting the temperature in a homogeneous layer of dry snow is presented. The model, which is physically based, is capable of predicting diurnal temperature behaviour at the snow surface and at any depth within a snow layer given the variation in a limited set of meteorological parameters over that period. A sensitivity analysis is performed to determine the important parameters in the prediction of snow surface temperatures. These are found to be consistent with simple physical reasoning. 相似文献
1000.
The Kalman decomposition for a general class of implicit systems is introduced and studied. The properties of strong reachability, observability, acceptance of all inputs and outer sequences, output-uniqueness, uniqueness, and trajectory observability of the original system are related to the properties of its subsystems obtained via the Kalman decomposition. The problems of transfer relation, regularizability by feedback, output feedback, and output injection are studied by means of this decomposition 相似文献