DualToken-ViT: Position-aware Efficient Vision Transformer with Dual Token Fusion

Self-attention-based vision transformers (ViTs) have emerged as a highly competitive architecture in computer vision. Unlike convolutional neural networks (CNNs), ViTs are capable of global information sharing. With the development of various structures of ViTs, ViTs are increasingly advantageous for many vision tasks. However, the quadratic complexity of self-attention renders ViTs computationally intensive, and their lack of inductive biases of locality and translation equivariance demands larger model sizes compared to CNNs to effectively learn visual features. In this paper, we propose a light-weight and efficient vision transformer model called DualToken-ViT that leverages the advantages of CNNs and ViTs. DualToken-ViT effectively fuses the token with local information obtained by convolution-based structure and the token with global information obtained by self-attention-based structure to achieve an efficient attention structure. In addition, we use position-aware global tokens throughout all stages to enrich the global information, which further strengthening the effect of DualToken-ViT. Position-aware global tokens also contain the position information of the image, which makes our model better for vision tasks. We conducted extensive experiments on image classification, object detection and semantic segmentation tasks to demonstrate the effectiveness of DualToken-ViT. On the ImageNet-1K dataset, our models of different scales achieve accuracies of 75.4% and 79.4% with only 0.5G and 1.0G FLOPs, respectively, and our model with 1.0G FLOPs outperforms LightViT-T using global tokens by 0.7%

Polymersomes with aggregation-induced emission based on amphiphilic block copolypeptoids

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Fe³⁺@polyDOPA‑<i>b</i>‑polysarcosine, a T₁‑Weighted MRI Contrast Agent via Controlled NTA Polymerization

α-Amino acid <i>N</i>-thiocarboxyanhydrides (NTAs) are promising cyclic monomers to synthesize polypeptides and polypeptoids via controlled ring-opening polymerizations. Superior to <i>N</i>-carboxyanhydrides requiring protection on hydroxyl groups, NTAs are able to tolerate such nucleophiles. In this work, we report the synthesis of NTA monomers containing unprotected phenolic hydroxyl groups of 3,4-dihydroxy-l-phenylalanine (DOPA) and l-tyrosine (Tyr). Their controlled ROPs and sequential copolymerizations with polysarcosine (PSar) yield PDOPA, PTyr, and PDOPA-<i>b</i>-polysarcosine (PDOPA-<i>b</i>-PSar) products quantitatively with designable degrees of polymerization. Micellar nanoparticles of Fe³⁺@PDOPA-<i>b</i>-PSar have been prepared thanks to the strong chelation of iron­(III) cation by catechol ligands that act as T1-weighted magnetic resonance imaging (MRI) contrast agents. For instance, Fe³⁺@PDOPA₁₀-<i>b</i>-PSar₅₀ exhibits higher longitudinal relaxivity (<i>r</i>₁ = 5.6 mM^–1 s^–1) than commercial Gd³⁺-based compounds. Effective MRI contrast enhancement in vivo of nude mice with a moderate duration (150 min) and 3D magnetic resonance angiography in rabbit illustrated by using volume rendering and maximal intensity projection techniques ignite the clinical application of Fe³⁺-based polypept­(o)­ides in diagnostic radiology as Gd-free MRI contrast agents

Fe³⁺@polyDOPA‑<i>b</i>‑polysarcosine, a T₁‑Weighted MRI Contrast Agent via Controlled NTA Polymerization

α-Amino acid <i>N</i>-thiocarboxyanhydrides (NTAs) are promising cyclic monomers to synthesize polypeptides and polypeptoids via controlled ring-opening polymerizations. Superior to <i>N</i>-carboxyanhydrides requiring protection on hydroxyl groups, NTAs are able to tolerate such nucleophiles. In this work, we report the synthesis of NTA monomers containing unprotected phenolic hydroxyl groups of 3,4-dihydroxy-l-phenylalanine (DOPA) and l-tyrosine (Tyr). Their controlled ROPs and sequential copolymerizations with polysarcosine (PSar) yield PDOPA, PTyr, and PDOPA-<i>b</i>-polysarcosine (PDOPA-<i>b</i>-PSar) products quantitatively with designable degrees of polymerization. Micellar nanoparticles of Fe³⁺@PDOPA-<i>b</i>-PSar have been prepared thanks to the strong chelation of iron­(III) cation by catechol ligands that act as T1-weighted magnetic resonance imaging (MRI) contrast agents. For instance, Fe³⁺@PDOPA₁₀-<i>b</i>-PSar₅₀ exhibits higher longitudinal relaxivity (<i>r</i>₁ = 5.6 mM^–1 s^–1) than commercial Gd³⁺-based compounds. Effective MRI contrast enhancement in vivo of nude mice with a moderate duration (150 min) and 3D magnetic resonance angiography in rabbit illustrated by using volume rendering and maximal intensity projection techniques ignite the clinical application of Fe³⁺-based polypept­(o)­ides in diagnostic radiology as Gd-free MRI contrast agents