Regression-Based Camera Pose Estimation through Multi-Level Local Features and Global Features.

Accurate and robust camera pose estimation is essential for high-level applications such as augmented reality and autonomous driving. Despite the development of global feature-based camera pose regression methods and local feature-based matching guided pose estimation methods, challenging conditions, such as illumination changes and viewpoint changes, as well as inaccurate keypoint localization, continue to affect the performance of camera pose estimation. In this paper, we propose a novel relative camera pose regression framework that uses global features with rotation consistency and local features with rotation invariance. First, we apply a multi-level deformable network to detect and describe local features, which can learn appearances and gradient information sensitive to rotation variants. Second, we process the detection and description processes using the results from pixel correspondences of the input image pairs. Finally, we propose a novel loss that combines relative regression loss and absolute regression loss, incorporating global features with geometric constraints to optimize the pose estimation model. Our extensive experiments report satisfactory accuracy on the 7Scenes dataset with an average mean translation error of 0.18 m and a rotation error of 7.44° using image pairs as input. Ablation studies were also conducted to verify the effectiveness of the proposed method in the tasks of pose estimation and image matching using the 7Scenes and HPatches datasets.

Synthesis of Unimolecular Micelles with Incorporated Hyperbranched Boltorn H30 Polyester modified with Hyperbranched Helical Poly(phenyl isocyanide) Chains and their Enantioselective Crystallization Performance.

Here, the fabrication of unimolecular micelles functionalized with helical polymeric chains as a chiral nucleating agent in enantioselective crystallization is reported. Starting from a fractionated hyperbranched polyester (Boltorn H30), the ring-opening polymerization of l-lactic acid (LLA) and subsequent terminal-group modification affords the alkyne-Pd(II)-anchored hyperbranched macroinitiator (H30-PLLA-Pd). By taking advantage of a Pd(II)-catalyzed living polymerization of chiral pendant modified l- or d-phenyl isocyanide (PI) monomers, well-defined chiral unimolecular micelles (H30-PLLA-PPI) grafted with radiating helical PPI coronas of one predominant screw sense are obtained. The resultant chiral materials demonstrate excellent application in the enantioselective crystallization of racemic threonine in water, and a 92% enantiomeric excess value of the residual solution is obtained. It is believed this present proof of concept and methodology are facile and powerful for preparing novel and versatile chiral materials with different topological structures, not only applicable to PPI but also to other types of polymers.

Versatile pH-response Micelles with High Cell-Penetrating Helical Diblock Copolymers for Photoacoustic Imaging Guided Synergistic Chemo-Photothermal Therapy.

With high optical absorption efficiency, near infrared (NIR) dyes have been proposed as theranostic agents for fluorescence imaging, photoacoustic imaging (PAI), and photothermal therapy (PTT). However, inherent hydrophobicity and short circulation time of small molecule hinder the further biomedical application. Herein smart amphiphilic copolymer was synthesized containing IR780/camptothecin@poly(ε-caprolactone) (IR780/CPT@PCL) as core, helical poly(phenyl isocyanide) (PPI) blocks as shell with the pH-responsive rhodamine B (RhB) moieties in the core-shell interface. With hydrophilic helical PPI coronas, these micelles present significantly enhanced cell-penetrating capacity that plays a key role in facilitating intracellular delivery of various cargos. By encapsulating CPT and IR780 molecules, the multifunctional self-assemble probe has huge potential to realize functional cooperativity and adaptability for cancer diagnosis and therapy. The in vitro and in vivo experimental results demonstrate that the pH-triggered fluorescent responsiveness and strong acoustic generation permit them efficient fluorescent and PA signal sensing for cancer diagnosis. Moreover, with 808 nm laser irradiation, the generated heat significantly improves the drug release from PCL core, leading to synergetic chemo-photothermal therapy and decreases tumor recurrence rates in mice. Overall, the biocompatible multifunctional micelles with these combined advantages can potentially be utilized for PAI guided disease diagnosis and tumor ablation.

Stimuli-Responsive Block Copolymer-Based Assemblies for Cargo Delivery and Theranostic Applications.

Although a number of tactics towards the fabrication and biomedical exploration of stimuli-responsive polymeric assemblies being responsive and adaptive to various factors have appeared, the controlled preparation of assemblies with well-defined physicochemical properties and tailor-made functions are still challenges. These responsive polymeric assemblies, which are triggered by stimuli, always exhibited reversible or irreversible changes in chemical structures and physical properties. However, simple drug/polymer nanocomplexes cannot deliver or release drugs into the diseased sites and cells on-demand due to the inevitable biological barriers. Hence, utilizing therapeutic or imaging agents-loaded stimuli-responsive block copolymer assemblies that are responsive to tumor internal microenvironments (pH, redox, enzyme, and temperature, etc.) or external stimuli (light and electromagnetic field, etc.) have emerged to be an important solution to improve therapeutic efficacy and imaging sensitivity through rationally designing as well as self-assembling approaches. In this review, we summarize a portion of recent progress in tumor and intracellular microenvironment responsive block copolymer assemblies and their applications in anticancer drug delivery and triggered release and enhanced imaging sensitivity. The outlook on future developments is also discussed. We hope that this review can stimulate more revolutionary ideas and novel concepts and meet the significant interest to diverse readers.