Acoustic radiation force on a rigid cylinder near rigid corner boundaries exerted by a Gaussian beam field

Acoustic manipulation is one of the well-known technologies of particle control and a top research in acoustic field.Calculation of acoustic radiation force on a particle nearby boundaries is one of the critical tasks,as it approximates realistic applications.Nevertheless,it is quite difficult to solve the problem by theoretical method when the boundary conditions are intricate.In this study,we present a finite element method numerical model for the acoustic radiation force exerting on a rigid cylindrical particle immersed in fluid near a rigid corner.The effects of the boundaries on acoustic radiation force of a rigid cylinder are analyzed with particular emphasis on the non-dimensional frequency and the distance from the center of cylinder to each boundary.The results reveal that these parameters play important roles in acoustic manipulation for particle-nearby complicated rigid boundaries.This study verifies the feasibility of numerical analysis on the issue of acoustic radiation force calculation close to complex boundaries,which may provide a new idea on analyzing the acoustic particle manipulation in confined space.

The DELLA-ABI4-HY5 module integrates light and gibberellin signals to regulate hypocotyl elongation

Plant growth is coordinately controlled by various environmental and hormonal signals,of which light and gibberellin(GA)signals are two critical factors with opposite effects on hypocotyl elongation.Although interactions between the light and GA signaling pathways have been studied extensively,the detailed regulatory mechanism of their direct crosstalk in hypocotyl elongation remains to be fully clarified.Previously,we reported that ABA INSENSITIVE 4(ABI4)controls hypocotyl elongation through its regulation of cellelongation-related genes,but whether it is also involved in GA signaling to promote hypocotyl elongation is unknown.In this study,we showthat promotion of hypocotyl elongation by GA is dependent on ABI4 activation.DELLAs interact directly with ABI4 and inhibit its DNA-binding activity.In turn,ABI4 combined with ELONGATED HYPOCOTYL 5(HY5),a key positive factor in light signaling,feedback regulates the expression of the GA2ox GA catabolism genes and thus modulates GA levels.Taken together,our results suggest that the DELLA-ABI4-HY5 module may serve as a molecular link that integrates GA and light signals to control hypocotyl elongation.

Regulatory dynamics of the higher-plant PSI-LHCI supercomplex during state transitions

State transition is a fundamental light acclimation mechanism of photosynthetic organisms in response to the environmental light conditions.This process rebalances the excitation energy between photosystemI(PSl)and photosystem Il through regulated reversible binding of the light-harvesting complex Il(LHCll)to PSl.However,the structural reorganization of PSI-LHCI,the dynamic binding of LHCll,and the regulatory mechanisms underlying state transitions are less understood in higher plants.In this study,using cryoelectron microscopy we resolved the structures of PSI-LHCI in both state 1(PSI-LHCI-ST1)and state 2(PSILHCI-LHCll-ST2)from Arabidopsis thaliana.Combined genetic and functional analyses revealed novel contacts between Lhcb1 and PsaK that further enhanced the binding of the LHCll trimer to the PSI core with the known interactions between phosphorylated Lhcb2 and the PsaL/PsaH/PsaO subunits.Specifically,PsaO was absent in the PSI-LHCI-ST1 supercomplex but present in the PSI-LHCI-LHCIl-ST2 supercomplex,in which the PsaL/PsaK/PsaA subunits undergo several conformational changes to strengthen the binding of PsaO in ST2.Furthermore,the PSI-LHCI module adopts a more compact configuration with shorter Mg-to-Mg distances between the chlorophylls,which may enhance the energy transfer efficiency from the peripheral antenna to the PSl core in ST2.Collectively,our work provides novel structural and functional insights into the mechanisms of light acclimation during state transitions in higher plants.

Reply to “Comment on ‘A numerical investigation of the acoustic mode waves in a deviated borehole penetrating a transversely isotropic formation' ”

We appreciate the comment from Horne,Miller and Wang on the paper‘A numerical investigation of the acoustic mode waves in a deviated borehole penetrating a transversely isotropic formation’by Liu et al.(2015)[1],for the opportunity to consider and clarify the group and phase velocity issue in sonic logging with a deviated borehole penetrating a VTI formation.We re-read the paper by Liu et al.[1]and did some numerical tests and analyses.After discussions we agree that at