Search for: All records

Methods based on upward canopy gap fractions are widely employed to measure in-situ effective LAI (Le) as an alternative to destructive sampling. However, these measurements are limited to point-level and are not practical for scaling up to larger areas. To address the point-to-landscape gap, this study introduces an innovative approach, named NeRF-LAI, for corn and soybean Le estimation that combines gap-fraction theory with the neural radiance field (NeRF) technology, an emerging neural network-based method for implicitly representing 3D scenes using multi-angle 2D images. The trained NeRF-LAI can render downward photorealistic hemispherical depth images from an arbitrary viewpoint in the 3D scene, and then calculate gap fractions to estimate Le. To investigate the intrinsic difference between upward and downward gaps estimations, initial tests on virtual corn fields demonstrated that the downward Le matches well with the upward Le, and the viewpoint height is insensitive to Le estimation for a homogeneous field. Furthermore, we conducted intensive real-world experiments at controlled plots and farmer-managed fields to test the effectiveness and transferability of NeRF-LAI in real-world scenarios, where multi-angle UAV oblique images from different phenological stages were collected for corn and soybeans. Results showed the NeRF-LAI is able to render photorealistic synthetic images with an average peak signal-to-noise ratio (PSNR) of 18.94 for the controlled corn plots and 19.10 for the controlled soybean plots. We further explored three methods to estimate Le from calculated gap fractions: the 57.5° method, the five-ring-based method, and the cell-based method. Among these, the cell-based method achieved the best performance, with the r2 ranging from 0.674 to 0.780 and RRMSE ranging from 1.95 % to 5.58 %. The Le estimates are sensitive to viewpoint height in heterogeneous fields due to the difference in the observable foliage volume, but they exhibit less sensitivity to relatively homogeneous fields. Additionally, the cross-site testing for pixel-level LAI mapping showed the NeRF-LAI significantly outperforms the VI-based models, with a small variation of RMSE (0.71 to 0.95 m2/m2) for spatial resolution from 0.5 m to 2.0 m. This study extends the application of gap fraction-based Le estimation from a discrete point scale to a continuous field scale by leveraging implicit 3D neural representations learned by NeRF. The NeRF-LAI method can map Le from raw multi-angle 2D images without prior information, offering a potential alternative to the traditional in-situ plant canopy analyzer with a more flexible and efficient solution. 

Abstract Hydrophobic interactions are one of the fundamental driving forces of self‐assembly in living systems. It remains challenging to harness hydrophobicity to have a controllable and programmable assembly of DNA nanostructures. On the other hand, there is also a need to explore orthogonal hierarchical assembly strategies to be used as an additional toolset along with the traditional Watson–Crick base pairing to achieve complex superstructures. In this work, we rationally design and synthesize a series of low molecular weight hydrophobic molecules that are conjugated to single‐stranded DNA strands. By incorporating these modified DNA strands into the precisely defined locations of DNA tiles and origami nanostructures, we achieve controlled hierarchical assembly driven by hydrophobic interaction. We demonstrate a versatile hydrophobicity‐guided higher‐order assembly strategy by employing strategically engineered DNA nanostructures of increasing complexity, ranging from simple DNA tiles to complex origami structures, functionalized with these small hydrophobic molecules as programmable building blocks. 

Abstract DNA is a versatile abiomaterial for constructing nanostructures with biomedical and biotechnological applications. Among the methods available, DNA origami is a robust and widely recognized technique. Traditionally, most origami designs adopt antiparallel crossovers in both scaffold and staple strands, with less emphasis on parallel crossovers, which offer advantages like enhanced nuclease resistance and single‐strand routing potential. Here, a DNA origami nanostructure is designed, featuring two rotational panels that can be locked into configurations based on either antiparallel or parallel crossovers. By systematically varying the length and arrangement of these key staples, 36 pairs of antiparallel and parallel designs are studied in competitive folding tests, providing insights into the relative preference for each design. The 12 antiparallel and parallel designs are ranked, their folding pathways are examined, and nuclease resistance is assessed. The results reveal that the arrangement of staples near the central scaffold crossover is crucial for shifting between parallel and antiparallel conformations. Additionally, a two‐way isothermal transformation between antiparallel and parallel origami driven by toehold‐mediated displacement reactions is demonstrated, highlighting the potential of parallel designs as dynamic nanodevices for temperature‐sensitive environments. This study offers valuable insights into ‐ dynamics in antiparallel and parallel DNA origami, opening opportunities for designing  nanodevices based on parallel crossovers. 

Abstract DNA tiles serve as the fundamental building blocks for DNA self-assembled nanostructures such as DNA arrays, origami, and designer crystals. Introducing additional binding arms to DNA crossover tiles holds the promise of unlocking diverse nano-assemblies and potential applications. Here, we present one-, two-, and three-layer T-shaped crossover tiles, by integrating T junction with antiparallel crossover tiles. These tiles carry over the orthogonal binding directions from T junction and retain the rigidity from antiparallel crossover tiles, enabling the assembly of various 2D tessellations. To demonstrate the versatility of the design rules, we create 2-state reconfigurable nanorings from both single-stranded tiles and single-unit assemblies. Moreover, four sets of 4-state reconfiguration systems are constructed, showing effective transformations between ladders and/or rings with pore sizes spanning ~20 nm to ~168 nm. These DNA tiles enrich the design tools in nucleic acid nanotechnology, offering exciting opportunities for the creation of artificial dynamic DNA nanopores.