Effect of crystallographic orientations on transport properties of methylthiol-terminated permethyloligosilane molecular junction

The understanding of the influence of electrode characteristics on charge transport is essential in the field of molecular electronics.In this work,we investigate the electronic transport properties of molecular junctions comprising methylthiolterminated permethyloligosilanes and face-centered crystal Au/Ag electrodes with crystallographic orientations of(111)and(100),based on the ab initio quantum transport simulations.The calculations reveal that the molecular junction conductance is dominated by the electronic coupling between two interfacial metal–S bonding states,which can be tuned by varying the molecular length,metal material of the electrodes,and crystallographic orientation.As the permethyloligosilane backbone elongates,although theσconjugation increases,the decreasing of coupling induced by the increasing number of central Si atoms reduces the junction conductance.The molecular junction conductance of methylthiol-terminated permethyloligosilanes with Au electrodes is higher than that with Ag electrodes with a crystallographic orientation of(111).However,the conductance trend is reversed when the electrode crystallographic orientation varies from(111)to(100),which can be ascribed to the reversal of interfacial coupling between two metal–S interfacial states.These findings are conducive to elucidating the mechanism of molecular junctions and improving the transport properties of molecular devices by adjusting the electrode characteristics.

Two central circadian oscillators OsPRR59 and OsPRR95 modulate magnesium homeostasis and carbon fixation in rice

Photosynthesis,which provides oxygen and energy for all living organisms,is circadian regulated.Photosynthesis-associated metabolism must tightly coordinate with the circadian clock to maximize the efficiency of the light-energy capture and carbon fixation.However,the molecular basis for the interplay of photosynthesis and the circadian clock is not fully understood,particularly in crop plants.Here,we report two central oscillator genes of circadian clock,OsPRR95 and OsPRR59 in rice,which function as transcriptional repressors to negatively regulate the rhythmic expression of OsMGT3 encoding a chloroplast-localized Mg2+transporter.OsMGT3-dependent rhythmic Mg fluctuations modulate carbon fixation and consequent sugar output in rice chloroplasts.Furthermore,sugar triggers the increase of superoxide,which may act as a feedback signal to positively regulate the expression of OsPRR95 and OsPRR59.Taken together,our results reveal a negative-feedback loop that strengthens the crosstalk between photosynthetic carbon fixation and the circadian clock,which may improve plan adaptation and performance in fluctuating environments.