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This article presents the design and fabrication of a coplanar waveguide (CPW)-fed slot antenna on thin substrate for dual-band operation of wireless local-area network (WLAN) applications within 2.400–2.484 GHz and 5.150–5.350/5.725–5.825 GHz bandwidths. The prototype consists of a thin substrate and a CPW-fed slot antenna. To obtain sufficient bandwidth with -10 dB return loss, a thin substrate layer is inserted under the ground plate and the radiator. A thin substrate CPW-fed slot antenna that has a WLAN-band is used. The important design parameters are the slot's construction, width, length, the substrate height, and the CPW-fed gaps. From these optimized parameters, a CPW-fed slot antenna is fabricated and measured. The measured results of the fabricated antenna are obtained individually, at 1.70 and 2.40 GHz bandwidths, with a -10 dB return loss referenced to the center frequency, and with the individual peak gains at 1.37 and 1.78 dBi. The experimental radiation efficiency in both the E- and H-planes is shown to be a pass band total of 48–75%. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2799–2802, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24742 [ABSTRACT FROM AUTHOR]

The growth of vertical single-walled carbon nanotube (SWNT) arrays of uniform aerial distribution is achieved by oxygen assisted plasma enhanced chemical vapor deposition (PECVD) growth from nanopatterned catalyst arrays prepared by block copolymer lithography. Block copolymer lithography is an attractive nanopatterning method for generating a uniform catalyst particle array for carbon nanotube growth. Nevertheless, the scale of the catalyst particles patterned by block copolymer lithography is usually not small enough for SWNT growth. In this work, various methods to reduce the catalyst size have been investigated for SWNT growth. Nanopatterned iron catalyst arrays having a mean diameter of 9 nm were prepared via tilted evaporation of thin iron catalyst films over a block copolymer template with the nanopore size of 20 nm, followed by heat treatment at 600 °C. The catalyst particle size was further reduced to the size required for SWNT growth (∼3 nm) by the following two methods. In method i, the catalyst particles were sequentially annealed at 800 °C first in air and then in an H2atmosphere. The evaporation of iron atoms and subsequent reduction during heat treatment produced catalyst particles sufficiently small for SWNT growth. In method ii, an Al layer was deposited over the catalyst array, which decreased the exposed area of the catalyst particles. The effective catalyst particle size was thus reduced, which enabled the growth of SWNTs. [ABSTRACT FROM AUTHOR]

We demonstrate a straightforward approach for rapid growth of wall-number selected, N-doped CNT arrays. Highly uniform nanopatterned iron catalyst arrays were prepared by tilted deposition through block copolymer nanotemplates. PECVD growth of CNTs from the nanopatterned catalysts in an NH3environment generated vertical N-doped CNTs with a fine-tunability of their carbon wall numbers. The optimized growth conditions produced 52 μm long N-doped CNTs within 1 min. Owing to N-doping, the wall-number selected CNTs including DWNTs and TWNTs demonstrated enhanced electro-conductivity and chemical functionality. This remarkably fast growth of highly uniform N-doped CNTs, whose material properties and chemical functionalizability are reinforced by N-doping, offers a new area of large-scale nanofabrication, potentially useful for diverse nanodevices. [ABSTRACT FROM AUTHOR]

This paper presents the characteristics of the miniaturized Z-shaped meander-type antenna realized for 5.25-GHz wireless LAN systems. The proposed antenna consists of the modified meander line, corrugated shape, and shorting pin with coaxial feeding on the two-layered (air and FR4) substrate, which forms the letter “Z.” This proposed antenna has equivalent performance with about 44.87% of size reduction with respect to conventional antennas. Its maximum measured impedance bandwidth (-10-dB below) is approximately 300 MHz (5.05–5.35 GHz) or 5.76%, which meets to the bandwidth requirement of WLAN (5.15–5.35 GHz) systems. Details of the proposed antenna are described and experimental results of constructed prototypes also are presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1269–1271, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21673 [ABSTRACT FROM AUTHOR]

The cathode active materials Li[Ni0.6Co0.2Mn0.2]O2 are synthesized using different inorganic salts, sulfate [NiSO4⋅6H2O, CoSO4⋅7H2O, MnSO4⋅H2O], nitrate [M(NO3)2⋅6H2O (M = Ni, Co, Mn)] and acetate [M(CH3COO)2⋅4H2O (M = Ni, Co, Mn)]. The X-ray diffraction (XRD) patterns indicate that sulfate and nitrate starting materials formed a well-ordered hexagonal α-NaFeO2 layered structure (space group: 166, R...m). However, acetate starting material is led to a poorly layered structure compared to the other materials. Field emission scanning electron microscope (FE-SEM) images show that sulfate and acetate starting materials formed nano-sized primary particles with a size of about 200-500 nm and 300 nm, and void channels. However, the primary particles with a size of 300 nm from nitrate starting material agglomerate together to form micro-sized secondary particles. The initial discharge capacities of the sulfate, nitrate, and acetate starting materials are 138.3, 142.4, and 135.9 mAh g-1 at 1 C-rate in the voltage range 3.0-4.3 V vs. Li/Li+, respectively. The discharge capacity retentions of sulfate, nitrate, and acetate starting materials are 92.5%, 63.9%, and 78.1% at 1 C-rate after 50 cycles, and 83.2%, 48.0%, and 71.7% at 6 C-rate after 100 cycles, respectively. [ABSTRACT FROM AUTHOR]

Polyethylene separator of 300% uni-axial stretching ratio is dip-coated with sol-gel synthesized NiO nanoparticles. The crystalline structure and the porous nature of the synthesized NiOnano particles are confirmed using X-Ray diffractometer (XRD) and field emission scanning electron microscope (FE-SEM). The dip-coated stretched PE separator is to be observed with high ionic conductivity of 2.12 mS cm-1and lower MacMullin number of 3.9 compared to the uncoated stretched PE separator. With regard to the thermal behavior coated separator has around six times lower enthalpy value, lower weight loss, and lower thermal shrinkage behavior as proven by differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA) and even when exposed to high temperature, respectively. The above characteristics of coated separator enhance the safety of Li-ion batteries. The electrochemical property is tested using electrochemical cycler and Li-ion cells with coated separator possess a similar initial discharge capacity but with enhanced capacity retention ratio of 95.73%. The obtained cycling behavior is well scrutinized by plotting the discharge profile and also by measuring its interfacial stability i.e., charge transfer resistance (Rct) based on cycle numbers using electrochemical impedance spectroscope (EIS). Improved rate capability behavior of Li-ion cells with coated separator is also demonstrated. [ABSTRACT FROM AUTHOR]

A method for the modeling of polarization-electric field (P-E) hysteresis curves of ferroelectric thin film with asymmetric electrode configuration was developed. The hysteresis curve of the ferroelectric capacitor with asymmetric electrode materials is shifted due to the work function difference between the top and bottom electrodes and the apparent polarization values are reduced as the screening length increases. [ABSTRACT FROM AUTHOR]

Background: We evaluated the posterior tibial artery as an alternative arterial cannulation site to the radial artery in small children.Methods: A two-stage study was conducted. First, we evaluated the anatomical characteristics of the posterior tibial artery compared with the radial and dorsalis pedis arteries. Next, a parallel-arm single-blind randomized controlled study compared the initial success rate of ultrasound-guided arterial cannulation among three arteries as a primary outcome.Results: Sixty patients were analyzed in the observational study. The diameter of the posterior tibial artery (1.5 ± 0.2 mm) was similar to that of the radial artery (1.5 ± 0.2 mm) and larger than that of the dorsalis pedis artery (1.2 ± 0.2 mm; P < 0.001). The posterior tibial artery has a larger cross-sectional area (2.8 ± 1.1 mm) compared with the radial (2.3 ± 0.8 mm; P = 0.013) and dorsalis pedis arteries (1.9 ± 0.6 mm; P = 0.001). In total, 234 patients were analyzed in the randomized study. The first-attempt success rate of the posterior tibial artery (75%) was similar to that of the radial (83%; P = 0.129; odds ratio, 1.53; 95% CI, 0.69 to 3.37) and higher than that of the dorsalis pedis artery (45%; P < 0.001; odds ratio, 3.95; 95% CI, 1.99 to 7.87). Median cannulation time of the posterior tibial artery (21 s; interquartile range, 14 to 30) was similar to that of the radial artery (27 s; interquartile range, 17 to 37) and shorter than that of the dorsalis pedis artery (34 s; interquartile range, 21 to 50).Conclusions: The posterior tibial artery is a reasonable alternative to the radial artery for ultrasound-guided arterial cannulation in small children. [ABSTRACT FROM AUTHOR]

We present a flexible room temperature NO2 gas sensor consisting of vertical carbon nanotubes (CNTs)/reduced graphene hybrid film supported by a polyimide substrate. The reduced graphene film alone showed a negligible sensor response, exhibiting abnormal N–P transitions during the initial NO2 injection. A hybrid film, formed by the growth of a vertically aligned CNT array (with CNTs 20 μm in length) on the reduced graphene film surface, exhibited remarkably enhanced sensitivities with weak N–P transitions. The increase in sensitivity was mainly attributed to the high sensitivity of the CNT arrays. The outstanding flexibility of the reduced graphene films ensured stable sensing performances in devices submitted to extreme bending stress. [ABSTRACT FROM AUTHOR]