A Photonic Crystal Slab Laplace Differentiator

We introduce an implementation of a Laplace differentiator based on a photonic crystal slab that operates at transmission mode. We show that the Laplace differentiator can be implemented provided that the guided resonances near the $\Gamma$ point exhibit an isotropic band structure. Such a device may facilitate nanophotonics-based optical analog computing for image processing.Comment: Primary text 6 pages, 5 figures; Supplementary material 5 pages, 3 figure

1-(3,4-Dimethyl­benzyl­idene)-4-ethyl­thio­semicarbazide

The title compound, C12H17N3S, was prepared by the reaction of 4-ethyl­thio­semicarbazide and 3,4-dimethyl­benzaldehyde. The dihedral angle between the thiourea unit and the benzene ring is 7.09 (8)°. In the crystal, inversion dimers linked by pairs of N—H⋯S hydrogen bonds occur

Optimising the linear electron transport rate measured by chlorophyll a fluorescence to empirically match the gross rate of oxygen evolution in white light: towards improved estimation of the cyclic electron flux around photosystem I in leaves

The cyclic electron flux (CEF) around photosystem I (PSI) was discovered in isolated chloroplasts more than six decades ago, but its quantification has been hampered by the absence of net formation of a product or net consumption of a substrate. We estimated in vivo CEF in leaves as the difference (ΔFlux) between the total electron flux through PSI (ETR1) measured by a near infrared signal, and the linear electron flux through both photosystems by optimised measurement of chlorophyll a fluorescence (LEFfl). Chlorophyll fluorescence was excited by modulated green light from a light-emitting diode at an optimal average irradiance, and the fluorescence was detected at wavelengths >710 nm. In this way, LEFfl matched the gross rate of oxygen evolution multiplied by 4 (LEFO2) in broad-spectrum white actinic irradiance up to half (spinach, poplar and rice) or one third (cotton) of full sunlight irradiance. This technique of estimating CEF can be applied to leaves attached to a plant.This work was supported by a China Scholarship Council Fellowship (to M-M. Z.), and a grant from the Australian Research Council (to WSC, DP1093827)

N′-[4-(Dimethyl­amino)­benzyl­idene]furan-2-carbohydrazide

The title compound, C14H15N3O2, was prepared by the reaction of 4-(dimethyl­amino)­benzaldehyde and furan-2-carbohydrazide. The dihedral angle between the benzene ring and the furan ring is 25.59 (19)°. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O hydrogen bonds, forming chains along [010]