Simultaneous dual-region two-photon imaging of biological dynamics spanning over 9 mm in vivo

Biodynamical processes,especially in system biology,that occur far apart in space may be highly correlated.To study such biodynamics,simultaneous imaging over a large span at high spatio-temporal resolutions is highly desired.For example,large-scale recording of neural network activities over various brain regions is indispensable in neuroscience.However,limited by the field-of-view(FoV)of conventional microscopes,simultaneous recording of laterally distant regions at high spatio-temporal resolutions is highly challenging.Here,we propose to extend the distance of simultaneous recording regions with a custom micro-mirror unit,taking advantage of the long working distance of the objective and spatio-temporal multiplexing.We demonstrate simultaneous dual-region two-photon imaging,spanning as large as 9 mm,which is 4 times larger than the nominal FoV of the objective.We verify the system performance in in vivo imaging of neural activities and vascular dilations,simultaneously,at two regions in mouse brains as well as in spinal cords,respectively.The adoption of our proposed scheme will promote the study of systematic biology,such as system neuroscience and system immunology.

An ultra-thin piezoelectric nanogenerator with breathable,superhydrophobic,and antibacterial properties for human motion monitoring

Piezoelectric nanogenerators(PENGs)are promising for harvesting renewable and abundant mechanical energy with high efficiency.Up to now,published research studies have mainly focused on increasing the sensitivity and output of PENGs.The technical challenges in relation to practicability,comfort,and antibacterial performance,which are critically important for wearable applications,have not been well addressed.To overcome the limitations,we developed an all-nanofiber PENG(ANF-PENG)with a sandwich structure,in which the middle poly(vinylidene fluoride-co-hexafluoropropylene(P(VDF-HFP))/ZnO electrospun nanofibers serve as the piezoelectric layer,and the above and below electrostatic direct-writing P(VDF-HFP)/ZnO nanofiber membranes with a 110 nm Ag layer on one side that was plated by vacuum coating technique serve as the electrode layer.As the ANF-PENG only has 91μm thick and does not need further encapsulating,it has a high air permeability of 24.97 mm/s.ZnO nanoparticles in ANF-PENG not only improve the piezoelectric output,but also have antibacterial function(over 98%).The multifunctional ANF-PENG demonstrates good sensitivity to human motion and can harvest mechanical energy,indicating great potential applications in flexible self-powered electronic wearables and body health monitoring.

Micro-mechanical model for predicting the elasto-plastic behavior of composites based on secant formulation method

To predict the Elasto-Plastic Behaviors(EPBs)of aligned inclusions reinforced composites,this paper develops an interpolative Mori-Tanaka/Double-Inclusion(MT-DI)homogenization model with the secant formulation,and gives the numerical implementation algorithms of the developed MT-DI model with the secant formulation.The Finite Element(FE)homogenization method is implemented to provide the "exact" EPBs of the composites and thus validate the MT-DI model with the secant formulation.The MT-DI model with the 2 nd-order secant formulation is validated to provide the more accurate predictions,while the MT-DI model with the 1 st-order secant formulation always gives the stiffer predictions.The results show that using the macro-stress and macrostrain as the inputs,the MT-DI model with the secant formulation gives the identical predictions.The predictions of the MT-DI model with the secant formulation vary between those of the MT and DI models with the secant formulation.Meanwhile,the MT-DI model with the secant formulation does not predict the accurate EPBs for the phases of the composites.

Highly sensitive vector magnetic fiber sensor based on hyperbolic metamaterials

Hyperbolic metamaterials(HMMs) are novel artificial materials that excite the surface plasmon resonance(SPR) because of their unique hyperbolic dispersion properties. Herein, to the best of our knowledge, we propose the first HMM-based fiber SPR(HMM-SPR) sensor for vector magnetic detection. By selecting the composite materials and structural parameters of the HMM dispersion management, HMM-SPR sensors can achieve a high refractive index sensitivity of 14.43 μm/RIU. Vector magnetic field detection was performed with the HMM-SPR sensor encapsulated with a magnetic fluid. Compared with other ferrofluidbased magnetic field fiber sensors, the proposed sensor shows pronounced advantages in intensity and direction sensitivity of 1.307 nm/Oe and 7.116 nm/°, respectively. The sensor design approach presented in this paper provides an excellent demonstration of HMM-SPR sensors in various applications.

Dual Effects of Interfacial Interaction and Geometric Constraints on Structural Formation of Poly(butylene terephthalate)Nanorods

When the size of the material is smaller than the size of the molecular chain,new nanostructures can be formed by crystallizing polymers in nanoporous alumina.However,the effect of pore wall and geometric constraints on polymer nanostructures remains unclear.In this study,we demonstrate three new restricted nanostructures{upright-,flat-and tilting-ring}in polybutylene terephthalate(PBT)nanorods prepared from nanoporous alumina.The dual effects of geometrical constraints and interfacial interactions on the formation of PBT nanostructures were investigated for the first time by using X-ray diffraction and Cerius^(2) modeling packages.Under weak constraints,the interaction between pore wall and the PBT rings is dominant and the ring plane tends to be parallel to the pore wall and radiate outward to grow the upright-ring crystals.Surprisingly,in strong 2D confinement,a structural formation reversal occurs and geometrical constraints overpower the effect of pore wall.Rings tend to pile up vertically or obliquely along the long axis of the rod,so the flat-and tilting-ring crystals are predominate in the constrained system.In principle,our study of the nanostructure formation based on the geometrical constraints and the pore wall interfacial effects could provide a new route to manipulate the chain assembly at the nanoscale,further improving the performance of polymer nanomaterial.