The Rectenna (RECTifying antENNA), which was first demonstrated by William C. Brown in 1964 as a receiver for microwave power transmission, is now increasingly researched as a means of harvesting solar radiation. Tapping into the growing photovoltaic market, the attraction of the rectenna concept is the potential for devices that, in theory, are not limited in efficiency by the Shockley-Queisser limit. In this review, the history and operation of this 40-year old device concept is explored in the context of power transmission and the ever increasing interest in its potential applications at THz frequencies, through the infra-red and visible spectra. Recent modelling approaches that have predicted controversially high efficiency values at these frequencies are critically examined. It is proposed that to unlock any of the promised potential in the solar rectenna concept, there is a need for each constituent part to be improved beyond the current best performance, with the existing nanometer scale antennas, the rectification and the impedance matching solutions all falling short of the necessary efficiencies at THz frequencies. Advances in the fabrication, characterisation and understanding of the antenna and the rectifier are reviewed, and common solar rectenna design approaches are summarised. Finally, the socio-economic impact of success in this field is discussed and future work is proposed.

In eastern Europe, primary H. pylori resistance to metronidazole is considerable, and that to clarithromycin is similar to or slightly higher than that in western Europe. Resistance to amoxicillin, ciprofloxacin and tetracycline was detected in several centers. Primary and post-treatment resistance rates vary greatly between centers.

Controlling magnetism with electric field directly or through strain-driven piezoelectric coupling remains a key goal of spintronics. Here, we demonstrate that giant piezomagnetism, a linear magneto-mechanic coupling effect, is manifest in antiperovskite MnNiN, facilitated by its geometrically frustrated antiferromagnetism opening the possibility of new memory device concepts. Films of MnNiN with intrinsic biaxial strains of ±0.25% result in Néel transition shifts up to 60 K and magnetization changes consistent with theory. Films grown on BaTiO display a striking magnetization jump in response to uniaxial strain from the intrinsic BaTiO structural transition, with an inferred 44% strain coupling efficiency and a magnetoelectric coefficient α (where α = d B/d E) of 0.018 G cm/V. The latter agrees with the 1000-fold increase over CrO predicted by theory. Overall, our observations pave the way for further research into the broader family of Mn-based antiperovskites where yet larger piezomagnetic effects are predicted to occur at room temperature.

We have studied the anomalous Hall effect (AHE) in strained thin films of the frustrated antiferromagnet Mn 3 NiN. The AHE does not follow the conventional relationships with magnetization or longitudinal conductivity and is enhanced relative to that expected from the magnetization in the antiferromagnetic state below T N = 260 K. This enhancement is consistent with origins from the noncollinear antiferromagnetic structure, as the latter is closely related to that found in Mn 3 Ir and Mn 3 Pt where a large AHE is induced by the Berry curvature. As the Berry-phase-induced AHE should scale with spin-orbit coupling, yet larger AHE may be found in other members of the chemically flexible Mn 3 AN structure.

Fifty nine Salmonella Corvallis isolates from humans and food products in Bulgaria, Denmark, and Thailand were examined for antimicrobial susceptibility and characterized by pulsed-field gel electrophoresis (PFGE). Cephalosporin-resistant isolates were examined for the presence of genes encoding beta-lactamases by PCR and sequencing. Ten different PFGE types were observed. One type (30 isolates) was recovered in all three countries; three types were found only in Bulgaria, two only in Denmark, two only in Thailand, and two both in Denmark and Thailand. Ten isolates were susceptible to all antimicrobial agents tested, whereas 41 were resistant to three or more antimicrobials. Most resistance was observed among the isolates from Bulgaria. Of the 25 isolates from Bulgaria, 20 displayed resistance to ampicillin and the cephalosporins ceftiofur and cephalothin. All 20 isolates tested negative for bla (CMY-1), bla (CMY-2), and bla (ACC), but positive for bla (SHV), of which five were sequenced to bla (SHV-2). Plasmid profiling and hybridization revealed that the bla (SHV) gene was located on plasmids of approximately 70 kb. Five plasmid profiles were found among these 20 isolates. The plasmid profiling confirmed the PFGE-type and was able to further subdivide the strains. Seventeen of these 20 isolates contained also bla (TEM), of which nine representatives were sequenced to bla (TEM-1B), or bla (TEM-1H). One isolate contained bla (CTX-M-15), bla (SHV-2), and bla (TEM-1H), with the bla (CTX-M-15), and bla (TEM-1H) genes located on a 63-kb transferable plasmid. This study showed a high frequency of resistance among S. Corvallis isolated from humans and food products in Bulgaria, with a lower frequency in Thailand and Denmark. The clonal relatedness among the isolates from three countries could indicate a recent spread of this serovar.