Weak, Quiet Magnetic Fields Seen in the Venus Atmosphere.

The existence of a strong internal magnetic field allows probing of the interior through both long term changes of and short period fluctuations in that magnetic field. Venus, while Earth's twin in many ways, lacks such a strong intrinsic magnetic field, but perhaps short period fluctuations can still be used to probe the electrical conductivity of the interior. Toward the end of the Venus Express mission, an aerobraking campaign took the spacecraft below the ionosphere into the very weakly electrically conducting atmosphere. As the spacecraft descended from 150 to 140 km altitude, the magnetic field became weaker on average and less noisy. Below 140 km, the median field strength became steady but the short period fluctuations continued to weaken. The weakness of the fluctuations indicates they might not be useful for electromagnetic sounding of the atmosphere from a high altitude platform such as a plane or balloon, but possibly could be attempted on a lander

Enhanced eicosapentaenoic acid production by a new deep-sea marine bacterium Shewanella electrodiphila MAR441T

This is the final version of the article. Available from the publisher via the DOI in this record.There is another ORE record for this publication: http://hdl.handle.net/10871/33412Omega-3 fatty acids are products of secondary metabolism, essential for growth and important for human health. Although there are numerous reports of bacterial production of omega-3 fatty acids, less information is available on the biotechnological production of these compounds from bacteria. The production of eicosapentaenoic acid (EPA, 20:5ω3) by a new species of marine bacteria Shewanella electrodiphila MAR441T was investigated under different fermentation conditions. This strain produced a high percentage (up to 26%) of total fatty acids and high yields (mg / g of biomass) of EPA at or below the optimal growth temperature. At higher growth temperatures these values decreased greatly. The amount of EPA produced was affected by the carbon source, which also influenced fatty acid composition. This strain required Na+ for growth and EPA synthesis and cells harvested at late exponential or early stationary phase had a higher EPA content. Both the highest amounts (20 mg g-1) and highest percent EPA content (18%) occurred with growth on L-proline and (NH4)2SO4. The addition of cerulenin further enhanced EPA production to 30 mg g-1. Chemical mutagenesis using NTG allowed the isolation of mutants with improved levels of EPA content (from 9.7 to 15.8 mg g-1) when grown at 15°C. Thus, the yields of EPA could be substantially enhanced without the need for recombinant DNA technology, often a commercial requirement for food supplement manufacture.The authors acknowledge the support of the NERC ECOMAR program (NE/C512961/1) and the BBSRC-Croda Dorothy Hodgkin Postgraduate Award (DHPA) to Dr Jinwei Zhang

Shewanella electrodiphila sp. nov., a psychrotolerant bacterium isolated from Mid-Atlantic Ridge deep-sea sediments.

This is the author accepted manuscript. The final version is available from Microbiology Society via the DOI in this record.Strains MAR441(T) and MAR445 were isolated from Mid-Atlantic Ridge sediments from a depth of 2734 m, and were found to belong to the genus Shewanella. The strains were rod-shaped, pigmented, non-motile and capable of anaerobic growth either by fermentation of carbohydrates or by anaerobic respiration. The strains utilized a variety of electron acceptors, including nitrate and ferric compounds, and could utilize peptone when grown anaerobically in a two-chambered microbial fuel cell, which used carbon cloth electrodes and delivered a stable power output of ,150-200 mW m(-2). The major fatty acids were typical of the genus Shewanella, with major components C13 : 0, iso-C13 : 0, iso-C15 : 0, C16 : 0, C16 : 1ω7c, C18 : 1ω7c and C20 : 5ω3 fatty acids. The DNA G+C content of strains MAR441(T) and MAR445 was 42.4 mol%. 16S rRNA gene sequence analysis indicated that strains MAR441(T) and MAR445 were most closely related to Shewanella olleyana (sequence similarities 97.9% to the type strain). DNA-DNA hybridization demonstrated only 15.6-37.2% relatedness between strain MAR441(T) and the type strains of related species of the genus Shewanella. Phenotypic characteristics confirmed that these isolates constituted a novel species of the genus Shewanella, for which the name Shewanella electrodiphila sp. nov. is proposed; the type strain is MAR441(T) (5ATCC BAA-2408(T) = DSM 24955(T)).The authors acknowledge the support of the NERC ECOMAR programme (NE/C512961/1). J. Z. was the recipient of a BBSRC-Croda Dorothy Hodgkin Postgraduate Award

Ultra-low carrier concentration and surface dominant transport in Sb-doped Bi2Se3 topological insulator nanoribbons

A topological insulator is a new state of matter, possessing gapless spin-locking surface states across the bulk band gap which has created new opportunities from novel electronics to energy conversion. However, the large concentration of bulk residual carriers has been a major challenge for revealing the property of the topological surface state via electron transport measurement. Here we report surface state dominated transport in Sb-doped Bi2Se3 nanoribbons with very low bulk electron concentrations. In the nanoribbons with sub-10nm thickness protected by a ZnO layer, we demonstrate complete control of their top and bottom surfaces near the Dirac point, achieving the lowest carrier concentration of 2x10^11/cm2 reported in three-dimensional (3D) topological insulators. The Sb-doped Bi2Se3 nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications.Comment: 5 pages, 4 figures, 1 tabl

Gate-tuned normal and superconducting transport at the surface of a topological insulator

Three-dimensional topological insulators are characterized by the presence of a bandgap in their bulk and gapless Dirac fermions at their surfaces. New physical phenomena originating from the presence of the Dirac fermions are predicted to occur, and to be experimentally accessible via transport measurements in suitably designed electronic devices. Here we study transport through superconducting junctions fabricated on thin Bi2Se3 single crystals, equipped with a gate electrode. In the presence of perpendicular magnetic field B, sweeping the gate voltage enables us to observe the filling of the Dirac fermion Landau levels, whose character evolves continuously from electron- to hole-like. When B=0, a supercurrent appears, whose magnitude can be gate tuned, and is minimum at the charge neutrality point determined from the Landau level filling. Our results demonstrate how gated nano-electronic devices give control over normal and superconducting transport of Dirac fermions at an individual surface of a three-dimensional topological insulator.Comment: 28 pages, 5 figure

Power electronic-controlled high Q resonator theory with HTS technology

Power electronic-controlled switch has been used with a high-temperature superconductor (HTS) to develop an advanced high Q resonant circuit. With a HTS, a very high Q circuit can be achieved; consequently special aspects such as high voltage generation can be theoretically and practically realized. Theoretical study has been carried out for this concept and method, and this paper describes the theory of this high Q resonant circuit and the operational principle. © 2006 IEEE

The behavior of two-way reinfoced concrete slabs externally strengthened with steel plate to subject patch load

2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

HTS high Q resonant controller

High Tc superconductor (HTS) technology has been used to develop an advanced high Q resonant circuit and its devices. With a HTS, a very high Q circuit can be achieved; consequently special aspects such as high voltage generation and high current control can be theoretically and practically realized. Theoretical study has been carried out, as well as a practical approach has been made for the concept verification. This paper describes the theory of this high Q resonant circuit and the operational principle of its high voltage generation and current control

Comparative cost-based analysis of a novel plug-in hybrid electric vehicle with conventional and hybrid electric vehicles

© 2015 Universiti Malaysia Pahang. Hybrid electric vehicles provide higher fuel efficiency and lower emissions through the combination of the conventional internal combustion engine with electric machines. This paper analyzes and compares two types of hybrid electric powertrain with a conventional vehicle powertrain to study the lifetime costs of these vehicles. The novelty of the University of Technology Sydney plug-in hybrid electric vehicle (UTS PHEV) arises through a special power-splitting device and energy management strategy. The UTS PHEV and comparative powertrains are studied through numerical simulations to determine fuel consumption for the proposed low and high congestion drive cycles. Satisfactory results are achieved in terms of fuel economy, the all-electric range and electrical energy consumption for the UTS PHEV powertrain, providing significant improvement over the alternative powertrains. The analysis of these vehicles is extended to include a cost-based analysis of each powertrain in order to estimate the total lifetime costs at different fuel prices. The results obtained from this analysis demonstrate that whilst the conventional powertrain is cheaper in terms of purchase and maintenance costs, both alternative configurations are more cost-effective overall as the average price of fuel increases