A vectorial model for the nonlinear gradient force exerted on metallic Rayleigh nanoparticles

Optical tweezers have proved to be a powerful tool with a wide range of applications. The gradient force plays a vital role in the stable optical trapping of nano-objects. The scalar method is convenient and effective for analyzing the gradient force in traditional optical trapping. However, when the third-order nonlinear effect of the nano...

Theoretical investigation on the effect of volume fraction in the optical trapping of gold nanoparticles

Stable optical trapping of gold nanoparticles is essential and desirable because of its wide applications in nanotechnology. While several factors have been proposed to affect optical trapping stability, the sample's volume fraction during optical trapping has often been neglected. To address this, by utilizing the effective medium theory, we...

Nonlinear optical trapping effect with reverse saturable absorption

Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With the gradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise in sequence and thereby modulate the nonlinear properties of materials. In current nonlinear optical traps, however, the underlying physical...

Identification of metro-bikeshare transfer trip chains by matching docked bikeshare and metro smartcards

Metro-bikeshare integration, an important way of improving the efficiency of public transportation, has grown rapidly during the last decades in many countries. However, most previous analysis of metro-bikeshare transfer trips were based on limited sample size and the number of recognized metro-bikeshare trips were not sufficient. The primary...

Plant traits determining biogeomorphic landscape dynamics: A study on clonal expansion strategies driving cliff formation at marsh edges

Despite the well-recognized importance of plant traits for biogeomorphic development of landscapes, our understanding remains limited of how species-specific plant traits respond to and serve as drivers for the sedimentary dynamics within a biogeomorphic landscape. By manipulating a series of laboratory experiments, using mesocosms and a...

Salt marsh establishment in poorly consolidated muddy systems: effects of surface drainage, elevation, and plant age

Conservation and restoration of salt marsh ecosystems are becoming increasingly important because of the many ecosystem services they provide. However, the processes controlling salt marsh establishment and persistence, especially on bare tidal flats in muddy areas, remain unclear. As muddy sediments typically experience a restriction of soil...

Nonlinearity-modulated single molecule trapping and Raman scattering analysis

Single molecule detection and analysis play important roles in many current biomedical researches. The deep-nanoscale hotspots, being excited and confined in a plasmonic nanocavity, make it possible to simultaneously enhance the nonlinear light-matter interactions and molecular Raman scattering for label-free detections. Here, we...

A plasmonic spanner for metal particle manipulation

Typically, metal particles are difficult to manipulate with conventional optical vortex (OV) tweezers, because of their strong absorption and scattering. However, it has been shown that the vortex field of surface plasmonic polaritons, called plasmonic vortex (PV), is capable of stable trapping and dynamic rotation of metal particles, especially...

Dynamic plasmonic beam shaping by vector beams with arbitrary locally linear polarization states

Vector beams, which have space-variant state of polarization (SOP) comparing with scalar beams with spatially homogeneous SOP, are used to manipulate surface plasmon polarizations (SPPs). We find that the excitation, orientation, and distribution of the focused SPPs excited in a high numerical aperture microscopic configuration highly depend on...

Engineered Tumor Cell Apoptosis Monitoring Method Based on Dynamic Laser Tweezers

Monitoring the cells’ apoptosis progression could provide a valuable insight into the temporal events that initiate cell death as well as the potential for rescue of apoptotic cells. In this paper, we engineered a novel and robust method for monitoring apoptosis of tumor cells based on dynamic laser tweezers, using A549 and HeLa cell line as...