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Since the famous Swedish chemist Scheele described molybdenum blue for the first time in 1778, polyoxometalate (POM) chemistry has made significant progress in its more than 200-year history. Compared with...

Three new sandwich-type selenotungstate anion structures and Co1 show superior catalytic performance in the Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate under mild conditions.

[HNi(HO)NbO], representing the first high-nuclear nickel-cation-bridged polyoxoniobate, has been synthesized. It incorporates two [{NiO}(HO)(NbO)] and two [Ni(HO)NbO] subunits exhibiting a rhombus-like architecture. Furthermore, the solution behaviour was examined by electrospray ionization mass spectrometry and the magnetic properties in the low temperature range indicate the presence of ferromagnetic interactions.

This paper presents a simple and low cost solution for the implementation of a screw relaxing sensor based on ultra-high frequency (UHF) radio frequency identification (RFID) passive tags. The proposed method opportunistically uses the natural capability of a metallic screw (or a metallic part fixed on a plastic screw) to realize an electrical continuity between two electrical lines, which is exploited to realize an open/closed switch mechanism associated to the tightened/relaxed screw status. Several switch-like possible realizations are described according to different working environments and situations, as well as tag-sensor implementation schemes. Three tag-sensors are designed and manufactured to comply with metallic or non-metallic application surfaces and to work within the UHF RFID Chinese band 920.5-924.5 MHz, showing a reliable discrimination capability between well-tightened and relaxed screw states. Finally, parameters such as maximum detection surface and minimum detection time are evaluated for completing the analysis of the presented detection system. INDEX TERMS Antennas, Internet of Things, sensors, radio frequency identification (RFID), ultra-high frequency (UHF), tag-sensor, screw relaxing detection.