A diisopropyl-fluorophosphatase (DFPase) was purified from brain and ganglia of squid Todarodes pacificus steenstrup. The DFPase had a preference in hydrolysis toward diisopropylphosphorofluoridate (DFP). It also was able to hydrolyze O-1,2,2-trimethylpropyl methylphosphofluoridate (soman) and O-isopropyl methylphosphonofluoridate (sarin) at nearly equal hydrolytic rates but only 1/10 that of DFP. The hydrolytic activity toward diethyl-p-nitrophenylphosphate (paraoxon) was very low compared with DFP, soman, and sarin. The DFPase was purified 330-fold to a specific activity of 18,300 n mol/min/mg protein. Its molecular weight was 34,000 dalton determined by gel-filtration chromatography. Mn2+ stimulation of the DFPase was not observed when DFP and soman were the substrates, but with sarin, the rate increased onefold in the presence of 1.0 mM of Mn2+. Ethylenediamine tetraacetic acid disodium (EDTA-Na2) at 0.05 M inhibited the DFPase activity about 30%. It could be concluded that this DFPase belongs to the squid-type DFPase.

A magnetic near-field probe (H-field probe) with dual output has been developed using a four-layer printed circuit board (PCB) technique. To achieve the improvement of detection sensitivity, the symmetrical double-loop is adopted to double the detection signal while suppressing the electric field coupling, which is also illustrated in a circuit model. The calibration factor (defined as the ratio of the external magnetic field to the induced response voltage of the probe) of the proposed H-field probe reaches 37.74 [dB (A/m)/V] at 0.5 GHz with the loop area of 0.8 mm 2 , resulting in a better sensitivity than the single-loop probe. For the suppression of unwanted electric field a floating shield is added to the bottom of the probe, leading to an excellent common electric field suppression ratio of 29 dB in the frequency range up to 10 GHz. The probe is also characterised by parameters such as high differential electric field suppression, spatial resolution and probe influence on the device under test. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A dual‐band horizontally polarized (HP) antenna with omnidirectional radiation patterns is presented in this paper. The HP antenna is a vertical slot backed with a metal box, which is excited by a tapered feeding patch with a U‐slit for dual‐band operation. Good omnidirectional radiations are observed. A dual‐band dual‐polarized (DP) antenna is then developed by adding a dual‐band vertically polarized (VP) element to the HP element. The VP element is composed of two horizontal slots excited by a two‐branch feedline. The dual‐band DP antenna achieves an overlapped impedance bandwidth of 6% (2.34‐2.5 GHz) for the lower band and 15% (5.06‐5.91 GHz) for the upper band with an isolation of higher than 35 dB. Both the dual‐band HP and DP antennas are suitable to serve as WiFi/WLAN/ISM antennas for short‐range, low power wireless communications.

A novel circular polarization (CP) reconfigurable antenna is proposed. The CP antenna consists of two folded off‐center‐driven dipoles. By switching four PIN diodes in the off‐center‐driven dipoles, the senses of CP can be changed between the left‐handed CP and the right‐handed CP. Two parasitic rectangular loops are added to the folded off‐center‐driven dipoles to improve the bandwidth. A T‐shaped microstrip probe line is used to feed the antenna. Experimental results show that the CP reconfigurable antenna achieves an impedance bandwidth of 31% (2.05–2.8 GHz) for return los >10 dB and a CP bandwidth of 16% (2.3–2.7 GHz) for axial ratio <3 dB. The measured gain of the CP reconfigurable antenna is about 7 dBi.

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