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141.
Nanogap Array Fabrication Using Doubly Clamped Freestanding Silicon Nanowires and Angle Evaporations
Han Young Yu Chil Seong Ah In‐Bok Baek Ansoon Kim Jong‐Heon Yang Chang‐Guen Ahn Chan Woo Park Byung Hoon Kim 《ETRI Journal》2009,31(4):351-356
We present a simple semiconductor process to fabricate nanogap arrays for application in molecular electronics and nano‐bio electronics using a combination of freestanding silicon nanowires and angle evaporation. The gap distance is modulated using the height of the silicon dioxide, the width of the Si nanowires, and the evaporation angle. In addition, we fabricate and apply the nanogap arrays in single‐electron transistors using DNA‐linked Au nanoparticles for the detection of DNA hybridization. 相似文献
142.
143.
[reaction: see text] 2'-Deoxy-2'-C-difluoromethylene-4'-thiocytidine (4) as a potential antitumor agent was synthesized starting from L-xylose via 2-deoxy-2-C-difluoromethylene-4-thiosugar as a key intermediate. An elimination product, 8, was always formed as the major product during removal of the protecting groups under acidic or basic conditions. However, utilizing neutral reaction conditions to remove the protecting groups afforded the desired product 4 exclusively. 相似文献
144.
Surface-enhanced emission from single semiconductor nanocrystals 总被引:1,自引:0,他引:1
The fluorescence behavior of single CdSe(ZnS) core-shell nanocrystal (NC) quantum dots is dramatically affected by electromagnetic interactions with a rough metal film. Observed changes include a fivefold increase in the observed fluorescence intensity of single NCs, a striking reduction in their fluorescence blinking behavior, complete conversion of the emission polarization to linear, and single NC exciton lifetimes that are >10(3) times faster. The enhanced excited state decay process for NCs coupled to rough metal substrates effectively competes with the Auger relaxation process, allowing us to observe both charged and neutral exciton emission from these NC quantum dots. 相似文献
145.
Chang‐Woo Kim 《ETRI Journal》2006,28(3):386-388
Monolithic SiGe heterojunction bipolar transistor (HBT) variable gain amplifiers (VGAs) with a feedforward configuration have been newly developed for 5 GHz applications. Two types of the feedforward VGAs have been made: one using a coupled‐emitter resistor and the other using an HBT‐based current source. At 5.2 GHz, both of the VGAs achieve a dynamic gain‐control range of 23 dB with a control‐voltage range from 0.4 to 2.6 V. The gain‐tuning sensitivity is 90 mV/dB. At VCTRL= 2.4 V, the 1 dB compression output power, P1‐dB, and dc bias current are 0 dBm and 59 mA in a VGA with an emitter resistor and ‐1.8 dBm and 71mA in a VGA with a constant current source, respectively. 相似文献
146.
Tsai JZ Cao H Tungjitkusolmun S Woo EJ Vorperian VR Webster JG 《IEEE transactions on bio-medical engineering》2000,47(1):41-48
The apparent resistance of a finite-thickness layer measured with a four-electrode plunge probe depends on the electrode insertion depth, electrode spacing, and layer thickness, as well as the resistivity ratio of an underlying layer. A physical model consisting of air, a saline solution layer, and an agar layer simulates the real situation of resistivity measurement. The saline layer represents the finite-thickness layer whose resistivity is to be measured by a plunge electrode probe, and the agar layer represents an underlying perturbing layer. A micropositioner controls the insertion depth of the four electrodes into the saline solution. With the apparent resistance measured on a semi-infinite-thickness layer of saline solution as standard, measurement results show decreasing apparent resistance and increasing error with increasing electrode insertion depth. This information is important for correct measurement of myocardial resistivity in vivo and in vitro. 相似文献
147.
La Porta Thomas F. Ramjee Ramachandran Woo Thomas Sabnani Krishan K. 《Mobile Networks and Applications》1998,3(2):123-141
Wireless networks are characterized by simple end devices and limited bandwidth. One solution to address these and other limitations
of the wireless mobile environment that has been widely pursued is the placement of proxies, or agents, inside the network
to assist with application processing that would normally take place on end devices. These agents can additionally manipulate
data to reduce bandwidth requirements and assist in providing services. The design and implementation of a user agent is heavily
impacted by the application it supports. In this paper we present our experiences with user agents in two different types
of applications: telephony-based Personal Communication Services (PCS) and two-way messaging. To provide low latency service,
the PCS user agents are mobile so that they may be kept close to their end devices. The design of the PCS agents limits migration
overhead to the transfer of approximately 100 bytes of information in about 150 milliseconds. To provide advanced messaging
services, the messaging user agent supports flexible messages while limiting air interface bandwidth usage. The messaging
agents reduce uplink bandwidth usage by approximately 35% when applied to a cellular PCS system, and reduce message payloads
by 97%.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
148.
Hua P. Woo E.J. Webster J.G. Tompkins W.J. 《IEEE transactions on bio-medical engineering》1993,40(4):335-343
In electrical impedance tomography (EIT), the measured voltages are sensitive to electrode-skin contact impedance because the contact impedance and the current density through it are both high. Large electrodes were used to provide a more uniform current distribution and reduce the contact impedance. A large electrode differs from a point electrode in that it has shunting and edge effects that cannot be modeled by a single resistor. The finite-element method (FEM) was used to study the electric field distributions underneath an electrode, and three models were developed: a FEM model, a simplified FEM model, and a weighted load model. The FEM models considered both shunting and edge effects and closely matched the experimental measurements. It is concluded that FEM models of electrodes can be used to improve the performance of an electrical impedance tomography reconstruction algorithm 相似文献
149.
Woo Yong Lee Jong Beom Ra 《Electronics letters》1996,32(20):1871-1873
To improve the quality of reconstructed images for a given bit rate constraint, the assigned bits must be distributed efficiently using a set of admissible quantisers so that source distortion can be minimised. However, the optimal bit allocation scheme is usually not practical due to its large computational burden. The authors propose a new fast algorithm which needs less computing time than required by existing fast algorithms 相似文献
150.
Φ3 field theory in six space-time dimensions is used as a testing ground for the renormalization group. The consistency of the new method devised by 't Hooft is verified at the two-loop level by exhibiting certain cancellations among single pole coefficients, and also relations among double and single pole coefficients. This calculation is contrasted in efficiency with one using the Gell-Mann-Low equation in dimensionally regularized form for which a solution is obtained at the one-loop level, without neglecting mass dependence.The theory shares with asymptotically free ones the virtue of an asymptotically vanishing effective coupling constant. Indeed, the next to leading term in the beta function is also of opposite sign to the coupling constant. 相似文献