Hydrogel biomaterials with independent and combined variations in modulus and cell adhesion ligand gradients for guided neovascularization of engineered tissues

Figure 1. Gradient Hydrogel Scaffold Fabrication. (A) Schematic photo-frontal polymerization. (B) Precursor flow rate profiles during crosslinking. (C) Hydrogel sectioning along the gradient direction for quantification of spatial variation in material properties and vascular cell spheroid placement in different regions along the gradient(s). The engineering of large volume, metabolically demanding tissue requires the formation of rapid, stable, and functional neovascularization (new blood vessel formation) for oxygen and nutrient transport and removal of waste products to support viability, function, and restoration of newly formed tissue. Neovascularization is dependent on cell response to multiple spatiotemporal signals including, soluble and immobilized biochemical factors, as well as gradients of mechanical properties and physical structure provided by the 3D extracellular matrix (ECM); yet the individual and combined effects of these factors is poorly understood. Various polymerization techniques have been developed for creating gradient-based hydrogel scaffolds to promote rapid and guided neovascularization, however, most studies have focused on evaluating 3D cellular responses to scaffold embedded gradients of a single factor (i.e. growth factors). Herein we present free-radical approaches based on visible light frontal photopolymerization to synthesize synthetic poly(ethylene) glycol (PEG) hydrogel scaffolds with controllable, physiologically-relevant continuous gradients of elastic modulus and/or crosslink density, proteolytically mediated scaffold degradation (through incorporation of crosslinks susceptible to degradation by cell-secreted matrix-metalloproteinases) and immobilized concentration of cell adhesive peptide(RGD) ligands (through pendant RGD functionalized monofunctional acrylates). Scaffolds with desired gradients were created using a dual programmable syringe pump system to control the composition and flow rates of two distinct prepolymer solutions in the feed stream entering a reaction chamber simultaneously exposed to crosslinking via visible light = 514 nm) using an Argon Ion laser system (Figure 1 A,B). Using this approach proteolytically degradable hydrogel scaffolds were created with (1) gradients of elastic modulus (ranging from 660-1460 Pa) and proteolytic degradation while the immobilized RGD concentration was maintained uniform (2mM), (2) with uniform modulus (600 Pa) and proteolytic degradation with gradients of immobilized RGD concentration (0.48-0.98 mM) and (3) with varying RGD gradient characteristics including magnitude and slope (steep, intermediate and shallow slopes) (Figure 2).The effect of each type of gradient on 3D vascular sprouting parameters (invasion area, sprout length and number) was evaluated using a 3D co-culture spheroid model of sprouting angiogenesis. In scaffolds containing gradients of elastic modulus, the number of vascular sprouts increased in the opposing gradient direction while RGD gradient scaffolds promoted increases in the length of vascular sprouts towards the peptide gradient. Studies are currently underway to elucidate the effects the RGD gradient as scaffold modulus and proteolytic degradation kinetics are independently modulated on vascular sprouting. Finally strategies to spatially incorporate additional gradients such as peptides that enable affinity binding of growth factors or nanoparticles that provide spatiotemporal release of proangiogenic peptides within the scaffolds will be discussed. Please click Additional Files below to see the full abstract

Intergrated Segmentation and Detection Models for Dentex Challenge 2023

Dental panoramic x-rays are commonly used in dental diagnosing. With the development of deep learning, auto detection of diseases from dental panoramic x-rays can help dentists to diagnose diseases more efficiently.The Dentex Challenge 2023 is a competition for automatic detection of abnormal teeth along with their enumeration ids from dental panoramic x-rays. In this paper, we propose a method integrating segmentation and detection models to detect abnormal teeth as well as obtain their enumeration ids.Our codes are available at https://github.com/xyzlancehe/DentexSegAndDet

Process Reengineering: China\u27s Public Health Emergency Information System

The SARS crisis has exposed the inability of China’s fragile public health system to respond to emergencies. China’s central government has initiated a national project to establish a public health emergency information system (PHEIS). The purpose of this study is to investigate the ongoing development of China’s PHEIS. By using a functional coupling framework, the paper analyzes the weakness of the old public health system, describes the design and functionalities of PHEIS, and discusses implications on future system development from a process reengineering perspective

VCL Challenges 2023 at ICCV 2023 Technical Report: Bi-level Adaptation Method for Test-time Adaptive Object Detection

This report outlines our team's participation in VCL Challenges B Continual Test_time Adaptation, focusing on the technical details of our approach. Our primary focus is Testtime Adaptation using bi_level adaptations, encompassing image_level and detector_level adaptations. At the image level, we employ adjustable parameterbased image filters, while at the detector level, we leverage adjustable parameterbased mean teacher modules. Ultimately, through the utilization of these bi_level adaptations, we have achieved a remarkable 38.3% mAP on the target domain of the test set within VCL Challenges B. It is worth noting that the minimal drop in mAP, is mearly 4.2%, and the overall performance is 32.5% mAP

Tunable Quantum Anomalous Hall Effects in Ferromagnetic van der Waals Heterostructures

The quantum anomalous Hall effect (QAHE) has unique advantages in topotronic applications, but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices. Through systematic first-principles calculations, we predict that the in-plane magnetization induced QAHE with Chern numbers C = $\pm$1 and the out-of-plane magnetization induced QAHE with high Chern numbers C = $\pm$3 can be realized in a single material candidate, which is composed of van der Waals (vdW) coupled Bi and MnBi$_2$Te$_4$ monolayers. The switching between different phases of QAHE can be controllable by multiple ways, such as applying strain or (weak) magnetic field or twisting the vdW materials. The prediction of an experimentally available material system hosting robust, highly tunable QAHE will stimulate great research interest in the field. Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.Comment: 14 pages, 4 figure

Unusual microwave response and bulk conductivity of very thin fese0.3te0.7 films as a function of temperature

Results of X-band microwave surface impedance measurements of FeSe1-xTex very thin film are reported. The effective surface resistance shows appearance of peak at T less and near Tc when plotted as function of temperature. The authors suggests that the most well-reasoned explanation can be based on the idea of the changing orientation of the microwave magnetic field at a SN phase transition near the surface of a very thin film. The magnetic penetration depth exhibits a power-law behavior of delta lambda proportional to T with an exponent n = 2.4 at low temperatures, which is noticeably higher than in the published results on FeSe1-xTexsingle crystal. However the temperature dependence of the superfluid conductivity remains very different from the behavior described by the BCS theory. Experimental results are fitted very well by a two-gap model with delta1/kTc=0.43 and delta2/kTc=1.22,thus supporting s(+-)- wave symmetry. The rapid increase of the quasiparticle scattering time is obtained from the microwave impedance measurements.Comment: 13 pages, 13 figure

Simultaneous Single-Position Oblique Lateral Interbody Fusion Combined With Unilateral Percutaneous Pedicle Screw Fixation for Single-Level Lumbar Tuberculosis: A 3-Year Retrospective Comparative Study

Objective To illustrate a simultaneous single-position oblique lateral interbody fusion (SP-OLIF) combined with unilateral percutaneous pedicle screw fixation in treating single-level lumbar tuberculosis, compared with posterior-only approach in clinical and radiographic evaluations. Methods Consecutive patients who had undergone surgeries for single-level lumbar tuberculosis from January 2018 to December 2020 were retrospectively reviewed. The patients included were divided into SP-OLIF and posterior-only groups according to surgical methods applied, with follow-up for at least 36 months. Outcomes included estimated blood loss, operative time, and complications for safety evaluation; visual analogue scale (VAS), Oswestry Disability Index (ODI) for efficacy evaluation; erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) for evaluating tuberculosis activity; x-ray and computed tomography scan were used for radiographic evaluation. Results A total of 136 patients had been enrolled in the study (60 for SP-OLIF and 76 for Posterior-only). The median operative time, blood loss, and hospital stay in SP-OLIF group were significantly less, with a lower complication rate. Meanwhile, the SP-OLIF group showed substantially lower VAS in 1 and 7 days and decreased ODI in the first month postoperatively, without significant difference afterward. Similarly, the median CRP and ESR in SP-OLIF group were significantly lower in 3 and 7 days postoperatively. All indicators had reduced to normal after 3 months. No recurrence had been reported throughout the whole follow-up. Conclusion SP-OLIF was an efficient minimally invasive protocol for single-level lumbar tuberculosis, facilitating earlier clinical improvement, with decreased blood loss, operative time and hospital stay compared with posterior-only approach