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The authors present a novel compact wideband pattern-reconfigurable antenna with alternate reflector and radiator. The proposed antenna consists of a pair of step-shape patches, four switches and a coplanar waveguide feeding line. By setting the switches ON or OFF, the two step-shape patches can alternately switch between the radiator and the reflector. As a result, the proposed antenna is able to provide two-directional radiation patterns whose main beams are roughly directed in opposing directions from 3.7 to 6 GHz. Compared with other current pattern-reconfigurable antennas, the proposed antenna exhibits advantages of better back-to-front radiation ratio, more compact antenna size and wider operating band. In this investigation, the optimised size of the proposed antenna is 20 × 20 mm², which equates to 0.25 × 0.25λ²0 (λ0 is the wavelength at the low edge of the operating frequency band). In addition, the time-domain characteristics of the proposed antenna are presented and analysed. The antenna shows a good time-domain performance. Measured results are presented. [ABSTRACT FROM AUTHOR]

Magnesium diboride (MgB2) shows a wide application prospect in the field of low field DC application for its relatively simple structure and rather higher critical temperature than LTS. With the development of MgB2 composite superconductor manufacturing technology and cryogenic technology, developing conduction cooled superconducting MRI system with MgB2 composite superconductor is becoming increasingly feasible. An MgB2 superconducting magnet for MRI was developed. The MgB2 superconducting magnet is used to investigate the fundamental scientific problem of the MRI main magnet, including field uniformity and stability, influencing factors of MgB2 composite superconductor on field uniformity and stability. The superconducting magnet consists of 2 solenoids wound with MgB2 wire with the length of 60 m. The magnet has an outer diameter of 169 mm, an iron core diameter of 135 mm, and air gap of 32 mm. The superconducting magnet is fabricated and tested. The central magnetic field reaches 1.0 T when the current of the MgB2 magnet is 290 A. The central magnetic field is 0.39 T when the current of the MgB2 magnet is 100 A. In this paper, the minimum quench energy, the quench propagation velocity and the minimum propagation zone of the MgB2 composite conductor are measured. Main magnet for MRI with MgB2 composite superconductor is analysed and proposed, including magnet design and test results. By theoretical modeling and simulation, the detailed quench propagation of the magnet is further analysed. Finally, the stability criteria of conduction-cooled MRI magnet are established. [ABSTRACT FROM AUTHOR]

Magnesium diboride (MgB2) shows a wide application prospect in the field of low field DC application for its relatively simple structure and rather higher critical temperature than LTS. With the development of MgB2 composite superconductor manufacturing technology and cryogenic technology, developing conduction cooled superconducting MRI system with MgB2 composite superconductor is becoming increasingly feasible. An MgB2 superconducting magnet for MRI was developed. The MgB2 superconducting magnet is used to investigate the fundamental scientific problem of the MRI main magnet, including field uniformity and stability, influencing factors of MgB2 composite superconductor on field uniformity and stability. The superconducting magnet consists of 2 solenoids wound with MgB2 wire with the length of 60 m. The magnet has an outer diameter of 169 mm, an iron core diameter of 135 mm, and air gap of 32 mm. The superconducting magnet is fabricated and tested. The central magnetic field reaches 1.0 T when the current of the MgB2 magnet is 290 A. The central magnetic field is 0.39 T when the current of the MgB2 magnet is 100 A. In this paper, main magnet for MRI with MgB2 composite superconductor is analysed and proposed, including magnet design, test results, and field uniformity. [ABSTRACT FROM AUTHOR]

In 2005, rose plants ( Rosa rugosa cv. ‘Plena’) exhibiting typical phytoplasma disease symptoms of stunting, yellowing, witches’-broom and dieback were observed in Pingyin, Shandong Province, China. The disease, rose witches’-broom (RoWB), is progressively destructive and can be graft-transmitted. Polymerase chain reaction (PCR), sequencing of PCR products and electron microscopy were used to investigate the possible association of phytoplasma with RoWB. All results indicated that presence of phytoplasma in the symptomatic rose plants. Sequence alignment of 16S rRNA gene, tuf gene and rp gene confirmed that the phytoplasma associated with RoWB is the causal agent of Paulownia witches’-broom disease, which might be transmitted from the paulownia tree that is several meters away. To our knowledge, this is the first report of the molecular characterization of phytoplasma infecting rose in China. [ABSTRACT FROM AUTHOR]

Conical carbon fibers (CCFs) with carbon nanotubes (CNTs) as their cores were grown on graphite substrates with a chemical vapor deposition method. The CNT-cored CCFs were about several tens of micrometers in length. In the interaction with a probe system, the CNT core filaments demonstrated good mechanical strength. Furthermore, field emission currents around 100 μA were also attained from individual CNTs. The growth mechanism of this CNT/CCF combined structure is briefly discussed. Our method has provided a convenient and inexpensive approach to mass assembling CNTs to a carbon substrate. [ABSTRACT FROM AUTHOR]

HTS materials can be used to develop novel permanent magnet (PM) motor. Based on the experimental and theoretical investigations, it was observed that the multi-impulse magnetization strategy should be selected for the constraints such as the temperature distributions and mechanical strength of the motor. The asymmetrical field distribution of HTS would induce torque ripples and unbalanced force. Proper cares have to be taken to avoid irreversible demagnetization. Resin impregnation and enclosing the rotor in a can/sleeve may provide the rotor enough mechanical strength to enable its high speed applications. [ABSTRACT FROM AUTHOR]

Total AC losses in multi-filamentary, silver-sheathed Bi2Sr2Ca2Cu3Oy (Bi-2223) tape were measured as functions of transport current, applied magnetic field and frequency by electromagnetic and calorimetric methods. Results of both methods agree well with each other. The calorimetric method was employed to investigate the effect of the phase difference between transport current and applied field, Δj on total AC loss. Total loss changes significantly with Δj when applied magnetic field is perpendicular to the surface of the sample. The effect of Δj on total loss in parallel magnetic applied field is smaller. [ABSTRACT FROM AUTHOR]

HTS bulks can be used as flux-focusing elements in reluctance motors. As parts of the primary study, a small prototype reluctance motor was designed and constructed by using HTS YBCO bulks. The performance was analyzed based on magnetic field calculation. An experimental investigation was carded out on the prototype motor. Computed parameters are compared with test measurements, showing good agreement. Compared with the conventional synchronous reluctance motors, higher efficiency and smaller size make these motors very attractive for the applications, such as cryogenic pumps and flywheel drives. [ABSTRACT FROM AUTHOR]

In-situ high-pressure energy dispersive X-ray diffraction measurements on CuBa2-Ca3Cu4O10+δ(Cu-1234) have been performed by using diamond anvil cell (DAC) device with synchrotron radiation. The results suggest that the crystal structure of Cu-1234 superconductor is stable under pressures up to 34 GPa at room temperature. According to the Birch-Murnaghan equation of state, the bulk modulus is obtained to be ∼150 GPa. [ABSTRACT FROM AUTHOR]

The solanum fruit fly,Bactrocera latifrons(Hendel), is a major agricultural pest in Asia and Hawaii, and it is important to prevent its widespread invasion in plant quarantine. In this study we introduced a real-time polymerase chain reaction (PCR) essay, using SYBR Green I dye, to rapidly identifyB. latifronson an ABI PRISM 7700 sequence detection system. A latifron-specific PCR primer set was obtained based on mtDNA COI gene ofB. latifrons. NineBactrocerafruit flies,B. latifrons,Bactrocera dorsalis,Bactrocera papayae,Bactrocera carambolae,Bactrocera philippinensis,Bactrocera occipitalis,Bactrocera correcta,Bactrocera cucurbitaeandBactrocera tau, were used to determine the specificity of primers lati1 and lati2. A series of genomic DNA dilutions ofB. latifrons(0.01, 0.1, 1, 10, 20, 40 and 100 ng) were used to assess the sensitivity of the SYBR Green PCR. Template DNA concentration was one of the sources of variability in cycle threshold values (CT) and the optimum DNA concentration was between 1 and 20 ng. Genomic DNA isolated from larvae, pupae and adult specimens ofB. latifronswere used to assess the specificity of the SYBR Green PCR. Melting curve analysis and agarose gel electrophoresis was employed to check the specificity of PCR products. Similar amplification plots were obtained using DNA from the three different stages ofB. latifronswith primer set lati1/lati2. The melting temperature (Tm) of PCR products was 77.5 ± 0.1°C, and the length of the amplified fragment 366 bp. Given the specificity and sensitivity of the assay, combined with high speed, low cost and the possibility of automating, SYBR Green PCR can be used as a rapid and specific technique for pest species identification in plant quarantine. [ABSTRACT FROM AUTHOR]

Control of nutrients as nitrogen and phosphorus after discharge into lakes is necessary since it is difficult and costly to control within wastewater plants currently in China. This paper studied the cycling of phosphorus and nitrogen with water and sediments from two lakes in China. It is found that oxygen plays a critical role in regulating phosphorus and nitrogen cycling within water and sediments. Three different oxygenation methods including aeration, calcium peroxide and hydrogen peroxide were studied to control phosphorus and nitrogen in overlying water. In anoxic conditions, the P concentration in water increased from an average 14 µg/L to 115.2 µg/L for Xili Lake, and from an average 24 µg/L to 1,000 µg/L for Jinchun Lake. The concentration of ammonia increased under anoxic conditions, while the concentration of nitrate increased under oxic conditions. In anoxic conditions, the nitrate concentration decreased probably through denitrification. Both N and P accumulation processes can be controlled under the three treatments. The phosphorus removal efficiency from the water body was in the order of CaO2 addition > aeration > H2O2 addition, while controlling effectiveness for ammonia was in the order of aeration > CaO2 addition > H2O2 addition. [ABSTRACT FROM AUTHOR]

Fuzzy methods in remote sensing have received growing interest for their particular value in situations where the geographical phenomena are inherently fuzzy. A fuzzy approach is investigated for the classification of sub-urban land cover from remote sensing imagery and the evaluation of classification accuracy. Under the fuzzy strategy, fuzziness, intrinsic to both remotely sensed data and ground data, is accommodated and usefully explored. For comparative purposes, hard and fuzzy classifications were produced and tested using hard and fuzzy evaluation techniques. The results show that the fuzzy approach holds advantages over both conventional hard methods and partially fuzzy approaches, in which fuzziness in only the remotely sensed imagery is accommodated. It was found that Kappa coefficients were more than doubled when applying the fuzzy evaluation technique as opposed to the hard evaluation technique. Furthermore, the fuzzy approach paves the way towards an integrated handling of remotely sensed data and other spatial data. [ABSTRACT FROM AUTHOR]

We report a giant resistance drop induced by dc electrical currents in La0.67Ca0.33MnO3 epitaxial thin films. Resistance of the patterned thin films decreases exponentially with increasing current and a maximum drop shows at the temperature of resistance peak Tp. Variation of resistance with current densities can be scaled below and above Tp, respectively. This work can be useful for the future applications of electroresistance. [ABSTRACT FROM AUTHOR]