Low-loss narrowband filtering switch based on coaxial resonators

© 2013 IEEE. In this paper, a narrowband filtering switch with low loss and high selectivity is presented based on coaxial resonators for the first time. PIN diodes mounted on the printed circuit boards are embedded into a coaxial filter to enable ON and OFF states. In the ON-state, the PIN diodes are turned OFF, which do not introduce the loss and affect the linearity. Two transmission zeros are generated by a novel feeding structure, which improves the skirt selectivity. In the OFF-state, the PIN diodes are turned on. Then, lumped capacitors are loaded to the coaxial resonators so that the resonant frequencies of the resonators are changed. The passband at the operating frequency cannot be formed, resulting in high isolation. For demonstration, the coaxial-resonator-based filtering switch is designed and fabricated. Good agreement between simulated and measured results verifies the proposed ideas. Comparison with other reported filtering switches is given. The proposed filtering switch shows the advantages of high Q-factor, relatively compact size, and wide stopband responses, which is attractive in wireless systems

First-principles study of alkali-metal intercalation in disordered carbon anode materials

The intercalation of alkali metals in disordered carbon anode materials is studied by a combination of first-principles and machine-learning methods.</p

Mass spectrometry analysis reveals differences in the host cell protein species found in pseudotyped lentiviral vectors

Lentiviral vectors (LVs) have been successfully used in clinical trials showing long term therapeutic benefits. Studying the role of cellular proteins in lentivirus HIV-1 life cycle can help understand virus assembly and budding, leading to improvement of LV production for gene therapy. Lentiviral vectors were purified using size exclusion chromatography (SEC). The cellular protein composition of LVs produced by two different methods was compared: the transient transfection system pseudotyped with the VSV-G envelope, currently used in clinical trials, and a stable producer cell system using a non-toxic envelope derived from cat endogenous retrovirus RD114, RDpro. Proteins of LVs purified by size exclusion chromatography were identified by tandem mass spectrometry (MS/MS). A smaller number of cellular protein species were detected in stably produced vectors compared to transiently produced vector samples. This may be due to the presence of co-purified VSV-G vesicles in transiently produced vectors. AHNAK (Desmoyokin) was unique to RDpro-Env vectors. The potential role in LV particle production of selected proteins identified by MS analysis including AHNAK was assessed using shRNA gene knockdown technique. Down-regulation of the selected host proteins AHNAK, ALIX, and TSG101 in vector producer cells did not result in a significant difference in vector production

Coralline Sr/Ca and Mg/Ca thermometer for the northern South China Sea: calibration and primary application high resolution on high-resolution SST reconstructing

利用全谱直读等离子体光谱(ICP2AES) 的分析方法精确分析了南海珊瑚的SrPCa 和MgPCa 比值,结合实测表层海水温度(SST),标定了海南岛南部三亚海域和西沙海域两个滨珊瑚的SrPCa 和MgPCa 温度计。在此基础上,尝试对两个南海北部全新世时期的珊瑚进行SST记录重建。结果显示约540aB.P. (小冰期) 西沙海域夏季月均SST 较现代低约1℃,而约6 500aB.P. (大暖期) 海南岛三亚海域夏季月均SST则高出现代1.0～1.5℃。The method for precisely and simultaneously measuring the coralline Sr/Ca and Mg/Ca ratios was established using inductively coupled plasma atomic emission spectrometry (ICP-AES). Using this method, the high-resolution Sr/Ca and Mg/Ca ratios of two Porites lutea from Sanya, South Hainan Island and Xisha Islands were measured. By comparing to the instrumentally measured sea surface temperatures in these two areas, the coralline Sr/Ca thermometer and the Mg/Ca thermometer were calibrated. These two thermometers can provide SST records with an error bar < 0.2℃, and they are suitable for high-resolution SST reconstructions in these areas. Based on these two thermometers, two short SST records were reconstructed from two Holocene Porites corals of the northern South China Sea. The results indicated that the monthly summer SSTs in Xisha Islands at about 540 years ago (the Little Ice Age) were 1℃ lower than that at present, and the monthly summer SSTs in Sanya, southern Hainan Island at 6 500 years ago (the Megathermal) were about 1℃ to 1 5℃ higher than that at present.published_or_final_versio

Rice protein radicals: growth and stability under microwave treatment

published_or_final_versio

Recent changes of water discharge and sediment load in the Yellow River basin, China

The Yellow River basin contributes approximately 6% of the sediment load from all river systems globally, and the annual runoff directly supports 12% of the Chinese population. As a result, describing and understanding recent variations of water discharge and sediment load under global change scenarios are of considerable importance. The present study considers the annual hydrologic series of the water discharge and sediment load of the Yellow River basin obtained from 15 gauging stations (10 mainstream, 5 tributaries). The Mann-Kendall test method was adopted to detect both gradual and abrupt change of hydrological series since the 1950s. With the exception of the area draining to the Upper Tangnaihai station, results indicate that both water discharge and sediment load have decreased significantly (p&lt;0.05). The declining trend is greater with distance downstream, and drainage area has a significant positive effect on the rate of decline. It is suggested that the abrupt change of the water discharge from the late 1980s to the early 1990s arose from human extraction, and that the abrupt change in sediment load was linked to disturbance from reservoir construction.Geography, PhysicalGeosciences, MultidisciplinarySCI(E)43ARTICLE4541-5613

Enhanced performance in polymer photovoltaic cells with chloroform treated indium tin oxide anode modification

Enhanced performance of a poly(3-hexylthiophene):(6,6)-phenyl C61 butyric acid methyl ester bulk heterojunction polymer photovoltaic cell is reported by modifying the indium tin oxide (ITO) anode with chloroform solution. Instead of the traditional UV-ozone treatment, the optimized chloroform modification on ITO anode can result in an enhancement in the power conversion efficiency of an identical device, originating from an increase in the photocurrent with negligible change in the open-circuit voltage. The performance enhancement is attributed to the work function modification of the ITO substrate through the surface incorporation of the chlorine, and thus improved charge collection efficiency. © 2011 American Institute of Physics

Versatile computer-controlled system for characterization of gas sensing materials

Author name used in this publication: M. H. Wong2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Wideband Diplexer with Narrow Channel Spacing Using Hybrid Bandpass-Bandstop Structures

© 2013 IEEE. In this paper, a wideband diplexer with narrow channel spacing is designed by using hybrid bandpass-bandstop structures. Two wideband bandpass structures are designed with the transmission zeros at the upper or lower passband edges to achieve high skirt selectivity. Two bandstop structures based on half-wavelength coupled lines are integrated to the two bandpass structures to introduce additional transmission zeros and thus the skirt selectivity is further improved. Accordingly, two channel filters with high skirt selectivity and high stopband rejection are designed to realize a wideband microstrip diplexer with very narrow channel spacing. For verification, a wideband diplexer operating at 1.71-2.17 GHz and 2.30-2.70 GHz is implemented, which covers multiple frequency bands for different mobile systems. The measured results show excellent performance of passband flatness, high in-band isolation of better than 35 dB and low minimum insertion losses of 0.46 and 0.50 dB for the two channels