The characteristic response of domestic cats to plant iridoids allows them to gain chemical defense against mosquitoes.

Domestic cats and other felids rub their faces and heads against catnip (Nepeta cataria) and silver vine (Actinidia polygama) and roll on the ground as a characteristic response. While this response is well known, its biological function and underlying mechanism remain undetermined. Here, we uncover the neurophysiological mechanism and functional outcome of this feline response. We found that the iridoid nepetalactol is the major component of silver vine that elicits this potent response in cats and other felids. Nepetalactol increased plasma ß-endorphin levels in cats, while pharmacological inhibition of µ-opioid receptors suppressed the classic rubbing response. Rubbing behavior transfers nepetalactol onto the faces and heads of respondents where it repels the mosquito, Aedes albopictus Thus, self-anointing behavior helps to protect cats against mosquito bites. The characteristic response of cats to nepetalactol via the µ-opioid system provides an important example of chemical pest defense using plant metabolites in nonhuman mammals.

Proton Irradiation Tolerance of High-Efficiency Perovskite Absorbers for Space Applications.

Lead halide perovskite single layers with three grain sizes are subjected to proton-beam irradiation in order to assess the durability and radiation tolerance of perovskite solar cells (PSCs) against space radiation. Proton-beam irradiation is chosen because proton beams significantly affect solar cell performance in the space environment. We evaluate the effects of proton beams by focusing on the grain structure, crystal structure, and carrier lifetime of a perovskite single layer by using scanning electron microscopy, X-ray diffraction, photoluminescence (PL) spectra, and time-resolved PL (TRPL). The results show that proton irradiation does not significantly affect the grain structure and crystal structure of perovskite layer; the TRPL results show that the carrier lifetime inside the grain is constant up to a fluence of 1 × 1014 p+/cm2 and decreases significantly at a fluence of 1 × 1015 p+/cm2. Proton-beam radiation tolerance of the grain inside the perovskite layer is dominant in the radiation tolerance of PSCs.

Tolerance of Perovskite Solar Cell to High-Energy Particle Irradiations in Space Environment.

Materials to be used in the space environment have to withstand extreme conditions, particularly with respect to cosmic particle irradiation. We report robust stability and high tolerance of organolead trihalide perovskite solar cells against high-fluence electron and proton beams. We found that methylammonium and formamidinium-based lead iodide perovskite solar cells composed of TiO2 and a conductive polymer, as electron and hole transport materials, can survive against accumulated dose levels up to 1016 and 1015particles/cm2 of electrons (1 MeV) and protons (50 KeV), respectively, which are known to completely destroy crystalline Si-, GaAS-, and InGaP/GaAs-based solar cells in spacecraft. These results justify the superior tolerance of perovskite photovoltaic materials to severe space radiations and their usefulness in satellite missions.

Improved Syntheses of (+)-Iridomyrmecin and (-)-Isoiridomyrmecin, Major Components of Matatabilactone.

Improved syntheses'of iridomyrmecin and isoiridomyrmecin, major components of matatabilactone, are described. The synthesis features a direct transformation of nepetalactol into key intermediates by DIBAL-H reduction and provides an expeditious and straightforward production of iridoid lactones for biological investigations of the Matatabi phenomenon.