Beam codebook based beamforming protocol for multi-Gbps millimeter-wave WPAN systems

In order to realize high speed, long range, reliable transmission in millimeter-wave 60 GHz wireless personal area networks (60 GHz WPANs), we propose a beamforming (BF) protocol realized in media access control (MAC) layer on top of multiple physical layer (PHY) designs. The proposed BF protocol targets to minimize the BF set-up time and to mitigate the high path loss of 60 GHz WPAN systems. It consists of 3 stages, namely the device (DEV) to DEV linking, sector-level searching and beam-level searching. The division of the stages facilitates significant reduction in setup time as compared to BF protocols with exhaustive searching mechanisms. The proposed BF protocol employs discrete phase-shifters, which significantly simplifies the structure of DEVs as compared to the conventional BF with phase-and-amplitude adjustment, at the expense of a gain degradation of less than 1 dB. The proposed BF protocol is a complete design and PHY-independent, it is applicable to different antenna configurations. Simulation results show that the setup time of the proposed BF protocol is as small as 2% when compared to the exhaustive searching protocol. Furthermore, based on the codebooks with four phases per element, around 15.1 dB gain is achieved by using eight antenna elements at both transmitter and receiver, thereby enabling 1.6 Gbps-data-streaming over a range of three meters. Due to the flexibility in supporting multiple PHY layer designs, the proposed protocol has been adopted by the IEEE 802.15.3c as an optional functionality to realize Gbps communication systems.     

Conductivity changes of dodecylbezensulfonic acid-doped polyaniline during pressure loading/unloading

Conductivity changes of polyaniline (PANi) doped with alkylbenzenesulfonic acid were investigated during pressure loading/unloading. PANi was chemically synthesized with ethylbenzenesulfonic acid (EBSA), octylbezenesulfonic acid (OBSA), and dodecylbenzenesulfonic acid (DBSA). Pellets were made for the comparison of chain length effects of PANi doped with alkylbenzenesulfonic acid on the conductivity change during pellet compression and expansion. PANi doped with DBSA exhibited the highest response to the pressure change. Relative amounts of DBSA to aniline (ANi) were adjusted to find out the optimal composition. It was revealed that the relative compositions of DBSA to PANi of pellets are similar (S/N ratio = 0.29–0.35) irrespective of feed ratios, but the conductivity change of pellets upon pressure loading/unloading becomes greater as the increase of relative amounts of DBSA to ANi in synthetic media. The variations of the conductivity change during repeated pressure loading/unloading were also compared. PANi pellets prepared from a solution containing [DBSA]/[ANi] = 2/1 retained more than 80% of the initial conductivity change value after 2000 cycles.     

Controlled Topology of Block Copolymer Gate Insulators by Selective Etching of Cylindrical Microdomains in Pentacene Organic Thin Film Transistors

We investigate the effect of surface topology of a block copolymer/neutral surface/SiO₂ trilayered gate insulator on the properties of pentacene organic thin film transistor (OTFT) by the controlled etching of self assembled poly(styrene‐b‐methyl methacrylate) (PS‐b‐PMMA) block copolymer. The rms roughness of the uppermost block copolymer film directly in contact with pentacenes was systematically controlled from 0.27 nm to approximately 12.5 nm by the selective etching of cylindrical PMMA microdomains hexagonally packed and aligned perpendicular to SiO₂ layer with 20 and 38 nm of diameter and periodicity, respectively. Both mobility and On/Off ratio were significantly reduced by more than 3 orders of magnitudes with the film roughness in OTFTs having 60 nm thick pentacene active layer. The poor device performance observed with the etched thin film of block copolymer dielectric is attributed to a defective pentacene active layer and the mixed crystalline structure consisting of thin film and bulk phase arising from the massive nucleation of pentacene preferentially at the edge of each cylindrical etched hole.     

Structure,chemical stability and electrical conductivity of perovskite La0.6Sr0.4M0.3Fe0.7O3−δ (M = Co,Ti) oxides

The perovskite La_0.6Sr_0.4M_0.3Fe_0.7O_3?δ (M = Co, Ti) powders have been synthesized by the citrate gel method. The structural and chemical stability of the La_0.6Sr_0.4M_0.3Fe_0.7O_3?δ (M = Co, Ti) oxides were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. The electrical conductivities of the sintered La_0.6Sr_0.4M_0.3Fe_0.7O_3?δ (M = Co, Ti) ceramics were measured. The results demonstrate the chemical stability in H₂/helium (He) atmosphere of the La_0.6Sr_0.4Ti_0.3Fe_0.7O_3?δ oxide is improved significantly compared to that of the La_0.6Sr_0.4Co_0.3Fe_0.7O_3?δ oxide. The incorporation of Ti^3+/4+ ions in the perovskite structure can significantly stabilize the neighboring oxygen octahedral due to the stronger bonding strength, leading to the enhanced structural and chemical stability of the La_0.6Sr_0.4Ti_0.3Fe_0.7O_3?δ. In addition, the perovskite La_0.6Sr_0.4M_0.3Fe_0.7O_3?δ (M = Co, Ti) oxides possess much higher chemical stability in CO₂/He atmosphere than that of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ oxide, in which the perovskite structure is destroyed completely in a flowing CO₂-containing atmosphere.     

Phase Decomposition and Dielectric Properties of Reactively Sputtered Bismuth Zinc Niobate Pyrochlore Thin Films Deposited from Monoclinic Zirconolite Target

Thin films of Bi₂O₃-ZnO-Nb₂O₅ system with cubic pyrochlore structure can be deposited using both cubic and monoclinic (zirconolite) targets. When monoclinic target was used, the as-deposited phase was nonequilibrium cubic monophase. After post-annealing in the 600–800^C range, phase decomposition occurred, resulting in more thermodynamically stable cubic pyrochlore and monoclinic zirconolite phases. The dielectric properties, such as dielectric constant and electric field dependent tunability, showed a steep increase along with phase separation. However, dielectric loss had a reverse tendency. The maximum tunability was about 38%, which exceeds that of cubic pyrochlore monophase films deposited from cubic target.     

Expression of Kv1.5 K+ channels in activated microglia in vivo

OBJECTIVES: This study evaluated postoperative weight gain in children who received albumin versus crystalloid prime for cardiopulmonary bypass (CPB). DESIGN: A retrospective case-controlled study. Children whose extracorporeal (EC) circuit prime contained albumin (group 1) were matched with those whose prime contained only crystalloid (group 2) on the basis of age, weight, and surgical repair. SETTING: A university-based medical center. PARTICIPANTS: Seventy-six children (newborn to 4 years of age) who underwent CPB for correction of a congenital heart anomaly from 1993 to 1995. Group 1 underwent surgery from October 1994 to September 1995, and group 2 from February 1993 to September 1994. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Group 1 had less weight gain on postoperative days (PODs) 1, 2 and 3 compared with group 2 (p = 0.04 on POD 1). Albumin (grams per milliliter) prime and prime volume in milliliters per kilogram were the best predictors of weight gain (p < 0.004), with prime volume being the more important. Children who weighed less than 7.5 kg received more prime volume and had greater weight gain than children who weighed 7.5 kg or greater on PODs 1, 2, and 3 (p < 0.02). CONCLUSION: Data suggest that adding albumin to the EC circuit prime and minimizing the prime volume will result in less postoperative weight gain. Further prospective study with a larger sample is warranted to determine whether albumin prime offers other clinical benefits.     

Deterioration of device characteristics of MFSFET due to fatigue

Abstract

Change of device characteristics of the metal-ferroelectric-semiconductor FET (MFSFET) with the progress of fatigue of the ferroelectric thin film are simulated in this study. The field-dependent polarization model and the square-law FET model are employed in our simulation. C-V_G curves exhibit the accumulation, the depletion and inversion regions clearly. They also exhibit the memory window of 2V. I_D-V_D curves are composed of the triode and the saturation regions. The difference of saturation drain currents of the MFSFET device at the dual threshold voltages in I_D-V_D curve is 6mA/cm², which decreases as much as 50% after fatigue. Our model is expected to be very useful in the estimation of the behaviour of MFSFET devices with the progress of fatigue.     

Continuous low-voltage dc electroporation on a microfluidic chip with polyelectrolytic salt bridges

A microfluidic electroporator operating under a continuous low dc voltage (7 to approximately 15 V) is reported. The proposed electroporation microchip exploits the ionic conductivity of polyelectrolytic gel electrodes to precisely control the electric field that is applied to cells without bubble generation in the microchannel. In this study, pDADMAC (poly diallyldimethylammonium chloride) was used to efficiently apply the electric potential difference to the cells in the microchannels. Impedance analysis showed that the pDADMAC plugs could work as ionic conductors with a conductivity of approximately 16 S m(-1). In accordance with the calculation using CFD-ACE, an input voltage of only 10 V could generate an electric field of 0.9 kV cm(-1) across the microchannel; this meets the requirements for electropermeation. The electropermeation of K562 human chronic leukemia cells was observed in the microchip from 7 V, and the efficiency increased up to 60% upon the application of an input voltage of 15 V with a viability of 80%. An amount of 10(5) cells could be transfected every minute under a constant potential difference. The transfection and expression of DNA plasmids were also successfully demonstrated in the suspension cell line.     

TENORM aerosols in the Florida phosphate industry--assessment of lung fluid solubility and annual effective dose to workers

Inhalation exposure to workers in the Florida phosphate industry due to TENORM aerosols has not been adequately addressed owing to lack of aerosol information. One of the more critical factors is the absorption rate of inhaled radionuclides into blood. In this study, this parameter was characterised using an in vitro dissolution test. The solubility data and other aerosol information were then used for individualised dose assessments at six different Florida phosphate facilities. The solubility data support the selections of ICRP Publication 66 Type M for uranium and lead isotopes and Type S for thorium isotopes. Total annual effective doses are 0.34 +/- 0.12 mSv at granulator areas, 0.30 +/- 0.10 mSv at storage areas and 0.23 +/- 0.02 mSv at shipping areas. These findings are considerably lower than originally postulated in previous studies where no site-specific information on particle size and lung fluid solubility had been available.     

Aptamer biosensors for label-free colorimetric detection of human IgE based on polydiacetylene (PDA) supramolecules

In this study, we demonstrate an aptamer-based biosensor (apta-biosensor) using PDA liposomes for label-free detection of allergy diagnosis by hIgE detection. In order to detect the target hIgE, the surface of PDA liposome were functionalized with hIgE antibody and anti-hIgE aptamer as a receptor, and the target hIgE onto the receptors was detected by the change of fluorescence signal. The hIgE antibody-modified PDA liposome biosensor had a serious problem that the immune reaction between receptor and target could not powerfully affect the change of florescence signal on PDA liposome. In order to solve this problem, the anti-hIgE aptamer which was far smaller than whole antibody was introduced as the receptor for the PDA liposome system. An aptamer-based PDA liposome biosensor was able to measure a quantity of target protein with various concentrations and at this time the detection limit was 141 ng/mL of the hIgE concentration. These results enabled diagnosis of allergy disease by an aptamer-based PDA liposome biosensor because real allergic patients showed high concentration of hIgE in serum (greater than 290 ng/mL). Therefore, we suggest that aptamer-modified PDA supramolecules as promising candidates for development of label-free colorimetric biosensors.