Enhancing Mask Transformer with Auxiliary Convolution Layers for Semantic Segmentation.

Transformer-based semantic segmentation methods have achieved excellent performance in recent years. Mask2Former is one of the well-known transformer-based methods which unifies common image segmentation into a universal model. However, it performs relatively poorly in obtaining local features and segmenting small objects due to relying heavily on transformers. To this end, we propose a simple yet effective architecture that introduces auxiliary branches to Mask2Former during training to capture dense local features on the encoder side. The obtained features help improve the performance of learning local information and segmenting small objects. Since the proposed auxiliary convolution layers are required only for training and can be removed during inference, the performance gain can be obtained without additional computation at inference. Experimental results show that our model can achieve state-of-the-art performance (57.6% mIoU) on the ADE20K and (84.8% mIoU) on the Cityscapes datasets.

Widespread global peatland establishment and persistence over the last 130,000 y.

Glacial-interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (>40°N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.

Tandem fabrication of upconversion nanocomposites enabled by confined protons.

Lanthanide-doped upconversion nanoparticle (UCNP)-based nanocomposites can address the intrinsic limitations associated with UCNPs and bestow new functions on UCNPs, which can facilitate the development and application of UCNPs. However, the fabrication of UCNP-based composites typically suffers from complex operations, long-drawn-out procedures, and even loss or damage of UCNPs. Herein, we report a tandem fabrication strategy for the preparation of UCNP-based nanocomposites, in which protons, confined in the non-aqueous polar solvent, can produce ligand-free UCNPs for the direct fabrication of a composite without further treatment. Our studies show that the confined protons can be generated by diverse materials and can yield different types of ligand-free nanomaterials for desired composites. This versatile strategy enables a simple but scalable fabrication of UCNP-based nanocomposites, and can be extended to other nanomaterial-based composites. These findings should provide a platform for constructing multifunctional UCNP-based materials, and benefit potential applications of UCNPs in varied fields.

Organic Linkers Enable Tunable Transfer of Migrated Energy from Upconversion Nanoparticles.

Energy transfer plays a pivotal role in applying lanthanide-doped upconversion nanoparticles (UCNPs) as optical probes for diverse applications, particularly in biology and medicine. However, achieving tunable energy transfer from UCNPs to different acceptors remains a daunting challenge. Here, we demonstrate that using small organic molecules as linkers, the energy transfer from UCNPs to acceptors can be modulated. Specifically, organic linkers can enable efficient energy transfer from NaGdF4:Yb/Tm@NaGdF4 core-shell UCNPs to different acceptors. Moreover, the organic linker-mediated energy transfer can be facilely tuned by simply changing organic linkers. Based on our mechanistic investigations, the extraction of Gd3+ migrated energy from UCNPs by organic linkers and the subsequent energy injection from linkers to acceptors should be the two key processes for controlling the energy transfer. The tunable energy transfer from UCNPs allows us to design novel applications, including sensors and optical waveguides, based on UCNPs. These findings may open up new ways to develop UCNP-based bioapplications and advance further fabrication of hybrid upconversion nanomaterials.