Viscosity and degradation controlled injectable hydrogel for esophageal endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is a common procedure to treat early and precancerous gastrointestinal lesions. Via submucosal injection, a liquid cushion is created to lift and separate the lesion and malignant part from the muscular layer where the formed indispensable space is convenient for endoscopic incision. Saline is a most common submucosal injection liquid, but the formed liquid pad lasts only a short time, and thus repeated injections increase the potential risk of adverse events. Hydrogels with high osmotic pressure and high viscosity are used as an alternate; however, with some drawbacks such as tissue damage, excessive injection resistance, and high cost. Here, we reported a nature derived hydrogel of gelatin-oxidized alginate (G-OALG). Based on the rheological analysis and compare to commercial endoscopic mucosal resection (EMR) solution (0.25% hyaluronic acid, HA), a designed G-OALG hydrogel of desired concentration and composition showed higher performances in controllable gelation and injectability, higher viscosity and more stable structures. The G-OALG gel also showed lower propulsion resistance than 0.25% HA in the injection force assessment under standard endoscopic instruments, which eased the surgical operation. In addition, the G-OALG hydrogel showed good in vivo degradability biocompatibility. By comparing the results acquired via ESD to normal saline, the G-OALG shows great histocompatibility and excellent endoscopic injectability, and enables create a longer-lasting submucosal cushion. All the features have been confirmed in the living both pig and rat models. The G-OALG could be a promising submucosal injection agent for esophageal ESD

Analyzing Mushroom Structural Patterns of a Highly Compressible and Expandable Hemostatic Foam for Gastric Perforation Repair

Abstract Nature presents the most beautiful patterns through evolving. Here, a layered porous pattern in golden ratio (0.618) is reported from a type of mushroom ‐Dictyophora Rubrovalvata stipe (DRS). The hierarchical structure shows a mathematical correlation with the golden ratio. This unique structure leads to superior mechanical properties. The gradient porous structure from outside to innermost endows it with asymmetrical hydrophilicity. A mathematical model is then developed to predict and apply to 3D printed structures. The mushroom is then explored to repair gastric perforation because the stomach is a continuous peristaltic organ, and the perforated site is subject to repeated mechanical movements and pressure changes. At present, endoscopic clipping is ineffective in treating ulcerative perforation with fragile surrounding tissues. Although endoscopic implant occlusion provides a new direction for the treatment of gastric ulcers, but the metal or plastic occluder needs to be removed, requiring a second intervention. Decellularized DRS (DDRS) is found with asymmetric water absorption rate, super‐compressive elasticity, shape memory, and biocompatibility, making it a suitable occluder for the gastric perforation. The efficacy in blocking gastric perforation and promoting healing is confirmed by endoscopic observation and tissue analysis during a 2‐month study

Flexible Polyimide Nanocomposites with dc Bias Induced Excellent Dielectric Tunability and Unique Nonpercolative Negative‑<i>k</i> toward Intrinsic Metamaterials

Intrinsic metamaterials with negative-<i>k</i> that originated from random-structured materials have drawn increasing attention. Currently, intrinsic negative-<i>k</i> was mainly achieved in percolative composites by tailoring the compositions and microstructures. Herein, plasmalike negative-<i>k</i> was successfully achieved in multiwalled carbon nanotubes (MWCNT)/polyimide (PI) nanocomposites via applying external dc bias which exhibited excellent capability in conveniently and accurately adjusting negative-<i>k</i>. Mechanism analysis indicated that the localized charges at the interfaces between MWCNT and PI became delocalized after gaining energy from the dc bias, resulting in elevated concentration of delocalized charges, and hence the enhanced negative-<i>k</i>. Furthermore, it is surprising to observe that negative-<i>k</i> also appeared in multilayer nanocomposites consisting of alternating BaTiO₃/PI and PI layers, in which there was no percolative conducting network. On the basis of systematic analysis, it is proposed that the unique nonpercolative negative-<i>k</i> resulted from the mutual competition between plasma oscillations of delocalized charges and polarizations of localized charges. Negative-<i>k</i> appeared once the polarizations were overwhelmed by plasma oscillations. This work demonstrated that applying dc bias is a promising way to achieve highly tailorable negative-<i>k</i>. Meanwhile, the observation of unique nonpercolative negative-<i>k</i> and the clarification of underlying mechanisms offer new insights into negative-<i>k</i> metamaterials, which will greatly facilitate the exploration of high-performance electromagnetic metamaterials

Self-Frequency Tracking for Fixed-Ratio Switch-Capacitors in Data Center Application without Extra Sensors

Peer reviewed: TruePublication status: PublishedAs research into data centers progresses, the importance of resonant switched-capacitor converters in power supply design becomes more evident. Practical applications reveal that the values of resonant capacitors and inductors may deviate from their nominal values due to various factors, leading to resonant frequency instability. This instability poses a challenge to power electronics technology, affecting system reliability and performance. This paper analyzes the effect of frequency deviation on system functionality, identifies the relationship between output voltage and switching frequency, and proposes a self-tracking frequency strategy to address this issue. Through experimental validation, this approach shows that it maintains synchronization between switching and resonant frequencies, reducing losses associated with frequency misalignment. Simulation and experimental results validate the converter’s stable operation and its ability to achieve zero-voltage and zero-current switching.</jats:p

ONCE-3DLanes: Building Monocular 3D Lane Detection

We present ONCE-3DLanes, a real-world autonomous driving dataset with lane layout annotation in 3D space. Conventional 2D lane detection from a monocular image yields poor performance of following planning and control tasks in autonomous driving due to the case of uneven road. Predicting the 3D lane layout is thus necessary and enables effective and safe driving. However, existing 3D lane detection datasets are either unpublished or synthesized from a simulated environment, severely hampering the development of this field. In this paper, we take steps towards addressing these issues. By exploiting the explicit relationship between point clouds and image pixels, a dataset annotation pipeline is designed to automatically generate high-quality 3D lane locations from 2D lane annotations in 211K road scenes. In addition, we present an extrinsic-free, anchor-free method, called SALAD, regressing the 3D coordinates of lanes in image view without converting the feature map into the bird's-eye view (BEV). To facilitate future research on 3D lane detection, we benchmark the dataset and provide a novel evaluation metric, performing extensive experiments of both existing approaches and our proposed method. The aim of our work is to revive the interest of 3D lane detection in a real-world scenario. We believe our work can lead to the expected and unexpected innovations in both academia and industry.Comment: CVPR 2022. Project page at https://once-3dlanes.github.i