Triple band-notched UWB antenna using meandered ground stubs

In this paper, three pairs of meandered ground stubs are used to create a triple band-notched characteristic for a compact planar-monopole antenna used in the ultrawide band (UWB). The three band notches include the IEEE 802.16 (WiMax) band (3.3-3.6 GHz), the lower wireless area network (WLAN) band (5.15-5.35 GHz) and the higher WLAN band (5.725-5.825 GHz). The center frequencies and bandwidths of the notches can be adjusted using the dimensions of the meandered ground stubs. Prototype of the proposed antenna is designed and fabricated. The band-notched characteristics, return loss, radiation patterns, peak gains and efficiencies of the antenna are studied using both computer simulation and measurements. ©2010 IEEE.published_or_final_versionThe 2010 Loughborough Antennas and Propagation Conference (LAPC 2010), Loughborough, U.K., 8-9 November 2010. In Proceedings of LAPC, 2010, p. 341-34

Effects of ground-plane size on planar UWB monopole antenna

Planar monopole antennas have found widespread applications in wireless communication systems. Their advantages of compact size, omnidirectional radiation pattern and wide impedance bandwidth make them good candidates for the designs of ultra-wideband (UWB) antennas. This paper investigates the effects of the dimensions of the rectangular ground-plane on the return loss and efficiency of an elliptical planar monopole antenna for UWB applications. Computer simulation and measurement are carried out on a group of nine antennas with different rectangular ground plane sizes. The simulated and measured results on return loss agree well. However, the simulated and measured efficiencies do not agree well in the lower UWB band. The measured efficiency shows that the efficiency is affected more by the width rather than by the length of the ground plane while the length of the ground plane affects the lower cutoff frequency. © 2010 IEEE.published_or_final_versionThe 2010 IEEE Region 10 International Conference (TENCON 2010), Fukuoka, Japan, 21-24 November 2010. In TENCON (IEEE Region 10 Conference) Proceedings, 2010, p. 422-42

An antenna for UWB and Bluetooth standards with band-notched characteristic

This paper presents the design and results of a small size, integrated Bluetooth and Ultrawideband (UWB) planar monopole antenna with a band-notched characteristic in the WLAN band. The antenna consists of a dual-ring radiator as the primary radiation element for the Bluetooth and UWB bands and a complementary split-ring resonator (CSRR) to produce a notched characteristic at the center frequency of 5.5GHz. The return loss, voltage-standing-wave ratio (VSWR), radiation pattern and peak gain of the antenna are studied by computer simulation and verified by measurements which agree well with the simulation results. © 2009 IEEE.published_or_final_versionThe 2009 IEEE International Conference on Ultra-Wideband (ICUWB 2009), Vancouver, BC., 9-11 September 2009. In Proceedings of ICUWB, 2009, p. 170-17

Band-notched characteristic using meandered ground stubs for compact UWB antennas

In this paper, a pair of meandered ground stubs is used to design a single band-notched characteristic in a compact planar-monopole antenna for ultrawide band (UWB) applications. The single-band notch covers the wireless area network (WLAN) band from 5.15 GHz to 5.825 GHz. The center-notch frequency and notch bandwidth can be adjusted using the dimensions of the meandered ground stubs. Prototype of the proposed antenna is designed, fabricated and studied. The band-notched characteristics, return loss, radiation patterns, peak gains and efficiencies of the antenna are studied using both computer simulation and measurements. © 2010 IEEE.published_or_final_versionThe 2010 IEEE International Conference on Ultra-Wideband (ICUWB), Nanjing, China, 20-23 September 2010. In Proceedings of ICUWB2010, 2010, v. 1, p. 147-15

RAS AND RHO COREGULATE LIVER DEVELOPMENT AND HEPATOCELLULAR CARCINOMA IN ZEBRAFISH

Ph.DDOCTOR OF PHILOSOPH

Modeling of cable for measurements of small monopole antennas

Coaxial cable is often used for measurements of antennas inside anechoic chambers. In the measurement of a monopole antenna with a small ground-plane, the finite-sized ground causes the current to flow back from the radiator to the outer surface of the coaxial cable. This results in secondary radiation which introduces errors to the measured radiation pattern. To reduce the unwanted secondary radiation, the coaxial cable can be covered with EMI suppressant tubing materials. However, this introduces errors to the measured efficiency. In this paper, the models of the coaxial cable with and without suppressant tubing are developed and used for computer simulation. The cable effects on the measured results of a small monopole ultrawide band (UWB) antenna are studied by using the antenna measurement equipment Satimo StarLab and the EM simulation tool CST. The results show great agreements between the simulated and measured results. © 2011 IEEE.published_or_final_versio

2,2′-[Nonane-1,9-diylbis(nitrilo­methyl­idyne)]diphenol

In the title Schiff base compound, C23H30N2O2, the complete mol­ecule is generated by crystallographic twofold symmetry, with one C atom lying on the rotation axis. The nonane chain adopts a linear conformation and the hydr­oxy group forms an intra­molecular O—H⋯N hydrogen bond to the imine group

Stabilization and release of palm tocotrienol emulsion fabricated using pH-sensitive calcium carbonate

Calcium carbonate (CaCO3) has been utilized as a pH-responsive component in various products. In this present work, palm tocotrienols-rich fraction (TRF) was successfully entrapped in a self-assembled oil-in-water (O/W) emulsion system by using CaCO3 as the stabilizer. The emulsion droplet size, viscosity and tocotrienols entrapment efficiency (EE) were strongly affected by varying the processing (homogenization speed and time) and formulation (CaCO3 and TRF concentrations) parameters. Our findings indicated that the combination of 5000 rpm homogenization speed, 15 min homogenization time, 0.75% CaCO3 concentration and 2% TRF concentration resulted in a high EE of tocotrienols (92.59–99.16%) and small droplet size (18.83 ± 1.36 µm). The resulting emulsion system readily released the entrapped tocotrienols across the pH range tested (pH 1–9); with relatively the highest release observed at pH 3. The current study presents a potential pH-sensitive emulsion system for the entrapment and delivery of palm tocotrienols

Effects of environmental stresses and in vitro digestion on the release of tocotrienols encapsulated within chitosan-alginate microcapsules

Considering the health benefits of tocotrienols, continuous works have been done on the encapsulation and delivery of these compounds. In this study, we encapsulated tocotrienols in chitosan-alginate microcapsules and evaluated their release profile. Generally, these tocotrienols microcapsules (TM) displayed high thermal stability. When subjected to pH adjustments (pH 1–9), we observed that the release of tocotrienols was the highest (33.78 ± 0.18%) under basic conditions. The TM were also unstable against the effect of ionic strength, with a high release (70.73 ± 0.04%) of tocotrienols even at a low sodium chloride concentration (50 mM). As for the individual isomers, δ-tocotrienol was the most sensitive to pH and ionic strength. In contrast, β-/γ-tocotrienols were the most ionic-stable isomers but more responsive toward thermal treatment. Simulated gastrointestinal model showed that the chitosan-alginate-based TM could be used to retain tocotrienols in the gastric and subsequently release them in the intestines for possible absorption