Design and analysis of TX/RX dual microstrip antenna using FDTD at Ku-band

A TX/RX dual microstrip 8/spl times/4 array antenna for satellite communication is designed, fabricated and measured and its element characteristics are analysed using finite difference time domain (FDTD) method. TX/RX frequency ranges are 14.0-14.5 GHz, 11.7-12.75 GHz, respectively, and vertical and horizontal polarisations are used for TX and RX. This antenna uses microstrip direct feeding for RX and aperture coupled stripline feeding for TX and accommodates stacked elements for a high directivity and wide impedance bandwidth. FDTD gives more accurate results because of the consideration of finite structure and two imperfect ground planes. This element has a return loss below -8 and -14 dB over the TX and RX frequency ranges and a gain of 7.5 and 8.3 dBi at the centre frequency of TX and RX. Return loss below -10 and -14 dB and a gain of 21.4 and 20.0 dBi were achieved for the TX and RX array, respectively.     

Design of ultra-broadband on-glass antenna with a 250 /spl Omega/ system impedance for automobiles

The design of a very simple, ultra-broadband, on-glass antenna for automobiles is described. A 250 /spl Omega/ impedance system is proposed and a loop-based antenna structure with tuning arms is optimised by a genetic algorithm. The measured results on a prototype antenna show an average VSWR of 1.61 in the UHF and L bands.     

The effects of amine additives and flow rate on the performance of mixed-bed ion exchange at ultralow concentrations

Experimental data were obtained to evaluate the effects of amine additives for pH control of solution and the volumetric flow rate of feed solution on the performance of mixed-bed ion exchange for the removal of ionic impurities in solution. The experiments were performed under various temperatures and cation resin ratios by using a continuous column system with NaCl solution. The breakthrough curves of ions, plotted as the ratio of the effluent to influent concentration versus run time or treated solution volume, give detailed results about the effects of the existence of the pH controller, such as ammonia and morpholine, and the variable flow rate on the fate of each ion in the units. The experimental results show that the morpholine breakthrough occurs earlier than the ammonia breakthrough and that the effect of ammonia on both sodium and chloride exchange rates is more significant than that of morpholine. The addition of ammonia in solution results in the decrease of cation resin capacity for the sodium removal much more than the addition of morpholine. The step changes in the flow rate affect significantly the shapes of sodium and chloride breakthrough curves. The effluent concentrations of sodium and chloride change according to the flow rate. However, the effect increases with decreasing operation capacity of cation resin, while it becomes serious around the breakthrough time of chloride and negligible after the time.     

“Multipoint Force Feedback” Leveling of Massively Parallel Tip Arrays in Scanning Probe Lithography

Nanoscale patterning with massively parallel 2D array tips is of significant interest in scanning probe lithography. A challenging task for tip‐based large area nanolithography is maintaining parallel tip arrays at the same contact point with a sample substrate in order to pattern a uniform array. Here, polymer pen lithography is demonstrated with a novel leveling method to account for the magnitude and direction of the total applied force of tip arrays by a multipoint force sensing structure integrated into the tip holder. This high‐precision approach results in a 0.001° slope of feature edge length variation over 1 cm wide tip arrays. The position sensitive leveling operates in a fully automated manner and is applicable to recently developed scanning probe lithography techniques of various kinds which can enable “desktop nanofabrication.”     

Zirconium oxide nanotube surface prompts increased osteoblast functionality and mineralization

Electrochemical formation of tunable nanoscale oxide layers on biomedical metallic surfaces has recently drawn much attention in biomaterials research. In this study, we report on the cellular response to a unique vertically aligned, laterally spaced nanotube nanostructure made of zirconium oxide (ZrO₂) fabricated by anodization. The growth, morphology, and functionality of osteoblasts cultured on ZrO₂ nanotubes have been investigated. The initial adhesion and spreading was considerably improved on the nanotube surface as compared to a flat zirconium (Zr) surface without a nanostructure. The morphology of the adhered cells on the nanotube surface elicited a highly organized cytoskeleton with crisscross patterned actin, which was lacking on the flat Zr. Increased alkaline phosphatase activity levels and the formation of calcified extracellular matrix implied improved osteoblast functionality and mineralization on the nanotube substrate. This in vitro study suggests that the ZrO₂ nanotubes provided an enhanced osteoblast response and demonstrated their apparent role in providing a platform for bone growth.