Several popular approaches to 3D vision tasks process multiple views of the input independently with deep neural networks pre-trained on natural images, achieving view permutation invariance through a single round of pooling over all views. We argue that this operation discards important information and leads to subpar global descriptors. In this paper, we propose a group convolutional approach to multiple view aggregation where convolutions are performed over a discrete subgroup of the rotation group, enabling, thus, joint reasoning over all views in an equivariant (instead of invariant) fashion, up to the very last layer. We further develop this idea to operate on smaller discrete homogeneous spaces of the rotation group, where a polar view representation is used to maintain equivariance with only a fraction of the number of input views. We set the new state of the art in several large scale 3D shape retrieval tasks, and show additional applications to panoramic scene classification.

Timely restoration of blood supply after myocardial ischemia is imperative for the treatment of acute myocardial infarction but causes additional myocardial ischemia/reperfusion (MI/R) injury, which has not been hitherto effectively targeted by interventions for MI/R injury. Hence, the development of advanced nanomedicine that can reduce apoptosis of cardiomyocytes while protecting against MI/R in vivo is of utmost importance. Herein, a redox‐responsive and emissive TPE‐ss covalent organic framework (COF) nanocarrier by integrating aggregation‐induced emission luminogens and redox‐responsive disulfide motifs into the COF skeleton is developed. TPE‐ss COF allows for efficient loading and delivery of matrine, a renowned anti‐cryptosporidial drug, which significantly reduces MI/R‐induced functional deterioration and cardiomyocyte injury when injected through the tail vein into MI/R models at 5 min after 30 min of ischemia. Moreover, TPE‐ss COF@Matrine shows a drastic reduction in cardiomyocyte apoptosis and improvements in cardiac function and survival rate. The effect of the TPE‐ss COF carrier is further elucidated by enhanced cardiomyocyte viability and triphenyltetrazolium chloride staining in vitro. This work demonstrates the cardioprotective effect of TPE‐ss COFs for MI/R injury, which unleashes the immense potential of using COFs as smart drug carriers for the peri‐reperfusion treatment of ischemic heart disease with low cost, high stability, and single postoperative intervention.

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