Two-dimensional nanofluidic channels are emerging candidates for capturing osmotic energy from salinity gradients. However, present two-dimensional nanofluidic architectures are generally constructed by simple stacking of pristine nanosheets with insufficient charge densities, and exhibit low-efficiency transport dynamics, consequently resulting in undesirable power densities (<1 W m −2 ). Here we demonstrate MXene/Kevlar nanofiber composite membranes as high-performance nanofluidic osmotic power generators. By mixing river water and sea water, the power density can achieve a value of approximately 4.1 W m −2 , outperforming the state-of-art membranes to the best of our knowledge. Experiments and theoretical calculations reveal that the correlation between surface charge of MXene and space charge brought by nanofibers plays a key role in modulating ion diffusion and can synergistically contribute to such a considerable energy conversion performance. This work highlights the promise in the coupling of surface charge and space charge in nanoconfinement for energy conversion driven by chemical potential gradients.

In this paper, we revisit the joint probabilistic data association (JPDA) technique and propose a novel solution based on recent developments in finding the m-best solutions to an integer linear program. The key advantage of this approach is that it makes JPDA computationally tractable in applications with high target and/or clutter density, such as spot tracking in fluorescence microscopy sequences and pedestrian tracking in surveillance footage. We also show that our JPDA algorithm embedded in a simple tracking framework is surprisingly competitive with state-of-the-art global tracking methods in these two applications, while needing considerably less processing time.

Photoacoustic microscopy (PAM) does not rely on contrast agent to image the optical absorption contrast in biological tissue. It is uniquely suited for measuring several tissue physiological parameters, such as hemoglobin oxygen saturation, that would otherwise remain challenging. Researchers are designing new clinical diagnostic tools and multimodal microscopic systems around PAM to fully unleash its potential. However, the sizeable and opaque piezoelectric ultrasonic detectors commonly used in PAM impose a serious constraint. Our solution is a coverslip-style optically transparent ultrasound detector based on a polymeric optical micro-ring resonator (MRR) with a total thickness of 250 μm. It enables highly-sensitive ultrasound detection over a wide receiving angle with a bandwidth of 140 MHz, which corresponds to a photoacoustic saturation limit of 287 cm−1, at an estimated noise-equivalent pressure (NEP) of 6.8 Pa. We also established a theoretical framework for designing and optimizing the MRR for PAM.

We designed an all-optical photoacoustic probe for endoscopic applications by employing an optically-transparent, coverslip-type, polymeric micro-ring resonator ultrasonic sensor. We experimentally quantified the axial, tangential, and radial resolutions and angular sensitive stability of this probe. Using this probe, we achieved volumetric imaging of several phantoms. Our all-optical probe design offers clear benefit in integrating photoacoustic endoscope with other optical endoscopic imaging modalities to facilitate the transformation from bench to bedside.

Cellulose nanocrystals (CNCs) were used to improve the performance of poly(vinylidene fluoride) (PVDF), and the composite properties were characterized. The results showed that the prepared nanocomposites displayed the increases in mechanical properties. In particular, with the incorporation of 6 wt% CNCs, increases in tensile strength and dynamic storage modulus were observed. For hydrophilicity, the water contact angle decreased from 90°to 77°with the incorporation of only 3 wt% CNCs, indicating improved hydrophilicity. Addition of CNCs to PVDF also helped improve its thermal stability and crystallinity. It was suggested that CNCs played a nucleating role in the crystallization of PVDF, which was supported by the smaller size of PVDF spherulite observed from scanning electron microscopy analysis. Rheological results indicated that incorporation of CNCs also increased both melt storage modulus and shear viscosity of composites. Overall, our present work demonstrates that CNCs can provide PVDF with simultaneously improved properties.