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111.
Chen T.-M. Chiu Y.-M. Wang C.-C. Chan K.-U. Lin Y.-H. Huang M.-C. Lu C.-H. Wang W.-S. Hu C.-S. Lee C.-C. Huang J.-Z. Chang B.-I. Yen S.-C. Lin Y.-Y. 《Solid-State Circuits, IEEE Journal of》2007,42(5):983-991
A low-power fullband 802.11a/b/g WLAN transceiver in 0.15-mum CMOS technology is described. The zero-IF transceiver achieves a receiver noise figure of 4.4/4 dB for the 2.4-GHz/5-GHz bands, respectively. The corresponding sensitivity at 54-Mb/s operation is -72 dBm for 802.11g and -74 dBm for 802.11a using actual PER measurement. An on-chip PA delivers 20 dBm output P1-dB. A new I/Q compensation scheme is implemented in local oscillator (LO) and an image rejection of better than 52 dB is observed. The transmitter delivers 10/1.5 dBm (2.4-/5-GHz) EVM-compliant output power for a 64-QAM OFDM signal at 54-Mb/s. The power consumption is 117/135 mW (1.8-V) in the receive mode and 570/233.1 mW in the transmit mode for 2.4/5 GHz, respectively. The low power consumption, high integration and robustness (-40 to 140degC) make this transceiver suitable for portable applications 相似文献
112.
M. R. Melloch D. D. Nolte J. M. Woodall J. C. P. Chang D. B. Janes E. S. Harmon 《固体与材料科学评论》1996,21(3):189-263
When arsenides are grown by molecular beam epitaxy at low substrate temperatures, as much as 2% excess arsenic can be incorporated into the epilayer. This excess arsenic is in the form of antisites, but there is also a substantial concentration of gallium vacancies. With anneal, there is a significant decrease in the arsenic antisite and gallium vancancy concentrations as the excess arsenic precipitates. With further anneal, the arsenic precipitates coarsen. This combination of low substrate temperature molecular beam epitaxy and a subsequent anneal results in a broad spectrum of materials, from highly defected epilayers to a two-phase system of semimetallic arsenic precipitates in an arsenide semiconductor matrix. These materials exhibit some very interesting and useful electrical and optical properties. 相似文献
113.
Two-dimensional layered materials are considered ideal platforms to study novel small-scale optoelectronic devices due to their unique electronic structures and fantastic physical properties. However, it is urgent to further improve the light–matter interaction in these materials because their light absorption efficiency is limited by the atomically thin thickness. One of the promising approaches is to engineer the plasmonic environment around 2D materials for modulating light–matter interaction in 2D materials. This method greatly benefits from the advances in the development of nanofabrication and out-plane van der Waals interaction of 2D materials. In this paper, we review a series of recent works on 2D materials integrated with plasmonic environments, including the plasmonic-enhanced photoluminescence quantum yield, strong coupling between plasmons and excitons, nonlinear optics in plasmonic nanocavities, manipulation of chiral optical signals in hybrid nanostructures, and the improvement of the performance of optoelectronic devices based on composite systems. 相似文献
114.
Chang Hyeong Lee Kyung Duk Park Bongsoo Jang 《Journal of mathematical chemistry》2013,51(7):1945-1960
In this paper, we present the multistage homotopy perturbation method for finding the solution of the chemical kinetics with nonlinear reactions. We develop a general scheme for finding the analytic solution of chemical reaction networks and apply it to motivating chemical examples such as the enzyme kinetics model and the Brusselator model. We illustrate the numerical result for the models and show the accuracy of the method. 相似文献
115.
Bor-Wen Yang Shih-Yuan Wang Yu-Yen Wang Jyun-Jhang Cai Chung-Hao Chang 《Optical Review》2013,20(5):438-441
Albinism is a kind of congenital disease of abnormal metabolism. Poecilia reticulata (guppy fish) is chosen as the model to study the development of albinic embryos as it is albinic, ovoviviparous and with short life period. This study proposed an imaging method for penetrative embryo investigation using optical coherence tomography. By imaging through guppy mother’s reproduction purse, we found the embryo’s eyes were the early-developed albinism features. As human’s ocular albinism typically appear at about four weeks old, it is the time to determine if an embryo will grow into an albino. 相似文献
116.
Ching Hsuan Lin Yu Ren Feng Kang Hong Dai Hou Chien Chang Tzong Yuan Juang 《Journal of polymer science. Part A, Polymer chemistry》2013,51(12):2686-2694
A phenolic OH‐containing benzoxazine ( F‐ap ), which cannot be directly synthesized from the condensation of bisphenol F, aminophenol, and formaldehyde by traditional procedures, has been successfully prepared in our alternative synthetic approach. F‐ap was prepared by three steps including (a) condensation of 4‐aminophenol and 5,5'‐methylenebis(2‐hydroxybenzaldehyde) (1) , (b) reduction of the resulting imine linkage by sodium borohydride, and (c) ring closure condensation by formaldehyde. The key starting material, (1) , was prepared from 2‐hydroxybenzaldehyde and s‐trioxane in the presence of sulfuric acid. F‐ap is structurally similar to bis(3,4‐dihydro‐2H‐3‐phenyl‐1,3‐benzoxazinyl)methane ( F‐a, a commercial benzoxazine based on bisphenol F/aniline/formaldehyde) except for two phenolic OHs. The phenolic OHs can provide reaction sites with epoxy and 1,1'‐(methylenedi‐p‐phenylene)bismaleimide (BMI). The structure–property relationships between the thermosets of F‐ap /epoxy, F‐a /epoxy, F‐ap /BMI, and F‐a /BMI were discussed. Experimental data showed that thermosets based on F‐ap /epoxy and F‐ap /BMI provided much better thermal properties than those based on F‐a /epoxy and F‐a /BMI. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2686–2694 相似文献
117.
Variation of lateral doping (VLD) is applied to the epitaxial-layer drift region in LDMOSTs, resulting in non-uniform doping concentration. In addition to a decrease in on-resistance, it improves electric field distribution on the surface of drift region, and thus increases the breakdown voltage. We studied the condition of using the VLD technique, and compared it with the conventional technique of optimizing the epitaxial-layer uniform concentration. Results from TSPUREM 4 and MEDICI simulations indicate that when the epitaxial-layer doping concentration is 1.5 × 1015 cm−3, applying VLD to the drift region increases the breakdown voltage by as much as 34% (187-251 V), while the specific on-resistance is lowered by 55% (49-22 mΩ cm2), which are remarkable improvements. On the other hand, if the doping concentration of epitaxial-layer is already high, the improvement of applying VLD is limited. 相似文献
118.
Tae Woo Kim Hana Yoo In Young Kim Hyung‐Wook Ha Ah Reum Han Jong‐San Chang Ji Sun Lee Seong‐Ju Hwang 《Advanced functional materials》2011,21(12):2301-2310
Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as‐prepared manganese oxide–aluminum oxide nanocomposite is X‐ray amorphous whereas heat‐treatment gives rise to the crystallization of an α‐MnO2 phase at 600 °C and Mn3O4/Mn2O3 and γ‐Al2O3 phases at 800 °C. Electron microscopy and N2 adsorption‐desorption‐isotherm analysis clearly demonstrate that the as‐prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of ~20 nm and a surface area of >410 m2 g?1. Of particular interest is that the small particle size of the as‐prepared nanocomposite is well‐maintained up to 600 °C, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very‐high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals. 相似文献
119.
120.
Chang‐Ching Chan Mark S. Bolgar Dilusha Dalpathado David K. Lloyd 《Rapid communications in mass spectrometry : RCM》2012,26(12):1507-1514
A method has been developed to reduce the mass spectrometric ion signal suppression associated with the use of TFA as an additive in LC mobile phases. Through post‐column infusion of diluted NH4OH solution to LC eluents, the ammonium ion introduced causes the neutral analyte‐TFA ion pair to dissociate which consequently releases the protonated analyte as free ions into the gas phase (through regular electrospray ionization mechanisms). An ion signal improvement from 1.2 to 20 times for a variety of compounds had been achieved through the application of this method. The molar ratios of NH4OH:TFA which result in a reduction of signal suppression were determined to be between 0.5:1 and 50:1. In addition, it was shown that this NH4OH infusion method could reduce the level of doubly‐charged species and the product ions formed via in‐source collision. The use of diluted NH4OH solution is favorable since it is compatible with mass spectrometry analysis, and it is applicable in both positive and negative‐ion generation mode. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献