Nonreciprocal Metasurface with Space-Time Phase Modulation

Creating materials with time-variant properties is critical for breaking reciprocity that imposes fundamental limitations to wave propagation. However, it is challenging to realize efficient and ultrafast temporal modulation in a photonic system. Here, leveraging both spatial and temporal phase manipulation offered by an ultrathin nonlinear metasurface, we experimentally demonstrated nonreciprocal light reflection at wavelengths around 860 nm. The metasurface, with traveling-wave modulation upon nonlinear Kerr building blocks, creates spatial phase gradient and multi-terahertz temporal phase wobbling, which leads to unidirectional photonic transitions in both momentum and energy spaces. We observed completely asymmetric reflections in forward and backward light propagations within a sub-wavelength interaction length of 150 nm. Our approach pointed out a potential means for creating miniaturized and integratable nonreciprocal optical components.Comment: 25 pages, 5 figure

Wireless Power Transfer and Data Collection in Wireless Sensor Networks

In a rechargeable wireless sensor network, the data packets are generated by sensor nodes at a specific data rate, and transmitted to a base station. Moreover, the base station transfers power to the nodes by using Wireless Power Transfer (WPT) to extend their battery life. However, inadequately scheduling WPT and data collection causes some of the nodes to drain their battery and have their data buffer overflow, while the other nodes waste their harvested energy, which is more than they need to transmit their packets. In this paper, we investigate a novel optimal scheduling strategy, called EHMDP, aiming to minimize data packet loss from a network of sensor nodes in terms of the nodes' energy consumption and data queue state information. The scheduling problem is first formulated by a centralized MDP model, assuming that the complete states of each node are well known by the base station. This presents the upper bound of the data that can be collected in a rechargeable wireless sensor network. Next, we relax the assumption of the availability of full state information so that the data transmission and WPT can be semi-decentralized. The simulation results show that, in terms of network throughput and packet loss rate, the proposed algorithm significantly improves the network performance.Comment: 30 pages, 8 figures, accepted to IEEE Transactions on Vehicular Technolog

1-Butyl­pyridinium bis­(1,2-dicyano­ethene-1,2-dithiol­ato)nickelate(III)

The NiIII atom in the anion of the title complex, (C9H14N)[Ni(C4N2S2)2], is coordinated by four S atoms of two maleonitrile­dithiol­ate ligands, and exhibits a square-planar coordination geometry

Bis[1-(3-cyano­benz­yl)pyridinium] bis­(1,2-dicyano­ethene-1,2-dithiol­ato)nickelate(II)

In the ionic title complex, (C13H11N2)2[Ni(C4N2S2)2], the NiII ion is located on an inversion centre so the asymmetric unit contains one-half [Ni(mnt)2]2− dianion (mnt2− is maleonitrile­dithiolate) and one 1-(3-cyano­benz­yl)pyridinium cation ([CNBzPy]+). The NiII ion in the [Ni(mnt)2]2− anion is coordinated by four S atoms of two mnt2− ligands, and exhibits square-planar coordination geometry. In the [CNBzPy]+ cation, the benzene and pyridine rings are twisted with respect to the C/C/N plane incorporating the methyl­ene C atom that links them. The crystal structure is stabilized by Coulombic inter­actions

Bis(4-dimethyl­amino-1-ethyl­pyridinium) bis­(1,2-dicyano­ethene-1,2-dithiol­ato-κ2 S,S′)nickelate(II)

The asymmetric unit of the title complex, (C9H15N2)2[Ni(C4N2S2)2], comprises one 4-dimethyl­amino-1-ethyl­pyri­din­ium cation and one half of a [Ni(mnt)2]2− (mnt2− = maleo­nitrile­dithiol­ate) anion; the complete anion is generated by the application of a centre of inversion. The NiII ion is coordinated by four S atoms of two mnt2− ligands and exhibits a square-planar coordination geometry

3-Butyl-1-methyl-1H-imidazol-3-ium bis­(1,2-dicyano­ethene-1,2-dithiol­ato-κ2 S,S′)nickel(III)

In the title compound, (C8H15N2)[Ni(C4N2S2)2], the NiIII atom is coordinated by four S atoms of two maleonitrile­dithiol­ate ligands and exhibits a distorted square-planar geometry. In the crystal, the cations and anions are connected alternately by weak inter­molecular C—H⋯N hydrogen bonds, forming a zigzag chain along [201]

Purification and characterization of recombinant glucose dehydrogenase isolated from a hyperthermophilic Sulfolobus-like bacterium

This study aimed to clone and characterize a thermal resistant glucose dehydrogenase (GDH) and investigate its clinical potential. A Sulfolobus-like thermophilic microbe was first isolated from a hot spring in Taitung, Chihpen County, Taiwan. The gene encoding GDH was cloned from the bacterium and expressed in Escherichia coli. The molecular weight of the enzyme was found to be approximately 39,000 kDa. The enzyme is stable over pH 4.0 to 11.0 and has an optimum pH of 8.0. The thermostability range of the enzyme correlated well with that of the natural environment for Sulfolobus. The GDH showed high substrate specificity for glucose. GDH could be useful in biotechnological applications because of its higher thermostability and substrate specificity when compared with that of other glucose-degrading enzymes.Keywords: Glucose dehydrogenase, sequencing, glucose test strip, blood glucose meter, diabetes mellitu