Programming hydrogel adhesion with engineered polymer network topology

Hydrogel adhesion that can be easily modulated in magnitude, space, and time is desirable in many emerging applications ranging from tissue engineering, and soft robotics, to wearable devices. In synthetic materials, these complex adhesion behaviors are often achieved individually with mechanisms and apparatus that are difficult to integrate. Here, we report a universal strategy to embody multifaceted adhesion programmability in synthetic hydrogels. By designing the surface network topology of a hydrogel, supramolecular linkages that result in contrasting adhesion behaviors are formed on the hydrogel interface. The incorporation of different topological linkages leads to dynamically tunable adhesion with high-resolution spatial programmability without alteration of bulk mechanics and chemistry. Further, the association of linkages enables stable and tunable adhesion kinetics that can be tailored to suit different applications. We rationalize the physics of chain slippage, rupture, and diffusion that underpins emergent programmable behaviors. We then incorporate the strategy into the designs of various devices such as smart wound patches, fluidic channels, drug-eluting devices, and reconfigurable soft robotics. Our study presents a simple and robust platform in which adhesion controllability in multiple aspects can be easily integrated into a single design of a hydrogel network

Optimization of direct-hole cutting blasting technology for deep-buried layered surrounding rock diversion tunnels

Objective In recent years, the trend of tunnel blasting construction extending to depth is becoming more and more significant, and the influence of layered rock mass in deep buried diversion tunnel on cutting quality in blasting construction is the key to blasting construction. Methods In order to study the influence of the location of blasting in deep layered surrounding rock on the cut blasting, a three-dimensional finite element numerical calculation model was established by using ANSYS/LS-DYNA, based on the blasting excavation project of the diversion tunnel of San Gabán hydropower station in Peru. The damage area caused by cut blasting was analyzed, and the optimization scheme was put forward for field test. Results The results show that the boundary area of layered surrounding rock has a certain influence on the range of rock damage caused by cutting blasting. The closer to the boundary area of layered surrounding rock, the smaller the range of rock damage. In order to increase the damage area of cut blasting, the location of blasting should keep a certain distance from the boundary area of layered surrounding rock. Conclusion The optimized blasting scheme was tested on site and good blasting effect was achieved. In this study, numerical simulation was used to optimize the position of the cutting hole accroding to the law of rock damage evolution, which can improve the economy and safety of tunnel construction

Semantic-Based Building Extraction from LiDAR Point Clouds Using Contexts and Optimization in Complex Environment

The extraction of buildings has been an essential part of the field of LiDAR point clouds processing in recent years. However, it is still challenging to extract buildings from huge amount of point clouds due to the complicated and incomplete structures, occlusions and local similarities between different categories in a complex environment. Taking the urban and campus scene as examples, this paper presents a versatile and hierarchical semantic-based method for building extraction using LiDAR point clouds. The proposed method first performs a series of preprocessing operations, such as removing ground points, establishing super-points and using them as primitives for subsequent processing, and then semantically labels the raw LiDAR data. In the feature engineering process, considering the purpose of this article is to extract buildings, we tend to choose the features extracted from super-points that can describe building for the next classification. There are a portion of inaccurate labeling results due to incomplete or overly complex scenes, a Markov Random Field (MRF) optimization model is constructed for postprocessing and segmentation results refinement. Finally, the buildings are extracted from the labeled points. Experimental verification was performed on three datasets in different scenes, our results were compared with the state-of-the-art methods. These evaluation results demonstrate the feasibility and effectiveness of the proposed method for extracting buildings from LiDAR point clouds in multiple environments

Sequencing, Characterization, and Comparative Analyses of the Plastome of Caragana rosea var. rosea

To exploit the drought-resistant Caragana species, we performed a comparative study of the plastomes from four species: Caragana rosea, C. microphylla, C. kozlowii, and C. Korshinskii. The complete plastome sequence of the C. rosea was obtained using the next generation DNA sequencing technology. The genome is a circular structure of 133,122 bases and it lacks inverted repeat. It contains 111 unique genes, including 76 protein-coding, 30 tRNA, and four rRNA genes. Repeat analyses obtained 239, 244, 258, and 246 simple sequence repeats in C. rosea, C. microphylla, C. kozlowii, and C. korshinskii, respectively. Analyses of sequence divergence found two intergenic regions: trnI-CAU-ycf2 and trnN-GUU-ycf1, exhibiting a high degree of variations. Phylogenetic analyses showed that the four Caragana species belong to a monophyletic clade. Analyses of Ka/Ks ratios revealed that five genes: rpl16, rpl20, rps11, rps7, and ycf1 and several sites having undergone strong positive selection in the Caragana branch. The results lay the foundation for the development of molecular markers and the understanding of the evolutionary process for drought-resistant characteristics

Realizing simultaneously excellent energy storage and discharge properties in AgNbO3 based antiferroelectric ceramics via La3+ and Ta5+ co-substitution strategy

AgNbO3 based antiferroelectric (AFE) ceramics have large maximum polarization and low remanent polarization, and thus are important candidates for fabricating dielectric capacitors. However, their energy storage performances have been still large difference with those of lead-based AFEs because of their room-temperature ferrielectric (FIE) behavior. In this study, novel La3+ and Ta5+ co-substituted AgNbO3 ceramics are designed and developed. The introduction of La3+ and Ta5+ decreases the tolerance factor, reduces the polarizability of B-site cations and increases local structure heterogeneity of AgNbO3, which enhance AFE phase stability and refine polarization-electric field (P–E) loops. Besides, adding La3+ and Ta5+ into AgNbO3 ceramics causes the decrease of the grain sizes and the increase of the band gap, which contribute to increased Eb. As a consequence, a high recoverable energy density of 6.79 J/cm3 and large efficiency of 82.1%, which exceed those of many recently reported AgNbO3 based ceramics in terms of overall energy storage properties, are obtained in (Ag0.88La0.04)(Nb0.96Ta0.04)O3 ceramics. Furthermore, the discharge properties of the ceramic with discharge time of 16 ns and power density of 145.03 MW/cm3 outperform those of many lead-free dielectric ceramics

Effect of Surface Functionality on the Rheological and Self-Assembly Properties of Chitin and Chitosan Nanocrystals and Use in Biopolymer Films

Chitin nanocrystals (ChNCs) are unique to all other bio-derived nanomaterials in one aspect: the inherent presence of a nitrogen moiety. By tuning the chemical functionality of this nanomaterial, and thus its charge and hydrogen bonding capacity, one can heavily impact its macroscopic properties such as its rheological and self-assembly characteristics. In this study, two types of ChNCs are made using acid hydrolysis (AH-ChNCs) and oxidative (OX-ChNCs) pathways, unto which deacetylation using a solvent-free procedure is utilized to create chitosan nanocrystals (ChsNCs) of varying degree of deacetylation (DDA). These nanocrystals were then studied for their rheological behaviour and liquid crystalline ordering. It was found that with both deacetylation and carboxylation of OX-ChNCs, viscosity continually increased with increasing concentrations from 2-8 wt. %, contrary to AH-ChNC suspensions in the same range. Interestingly, increasing the amine content of ChNCs was not proportional to the storage modulus, where a peak saturation of amines provided the most stiffness. Conversely, while the introduction of carboxylation increased the elastic modulus of OX-ChNCs by an order of magnitude from that of AH-ChNCs, it was degraded by increasing DDA. Deacetylation and carboxylation both inhibited the formation of a chiral nematic phase. Finally, these series of nanocrystals were incorporated into biodegradable pectin-alginate films as a physical reinforcement, which showed increased tensile strength and Young’s modulus values for the films incorporated with ChsNCs. Overall, this study is the first to investigate how surface functionalization of chitin-derived nanocrystals can affect their rheological and liquid-crystalline properties, and how it augments starch-based pectin/alginate films as a physical reinforcement nanofiller

Chitosan Nanocrystals Synthesis via Aging and Application Towards Alginate Hydrogels for Sustainable Drug Release

In this article, we demonstrate a new and clean method for the fabrication of chitosan nanocrystals relying on aging. We provide metrics to showcase the greeness of this method. We are then using these materials as building block to fabricate alginate hydrogels, and demonstrated that they have superior properties for gelation and drug release.<br /

Effect of Yttrium-Incorporated TiO₂ Electron Transport Layer on the Photovoltaic Performance of Triple-Cation Perovskite Solar Cells

Achieving an excellent electron transport layer is significant for high-performance perovskite solar cells. A TiO2 compact film is extensively applied as an electron transport layer. However, some limiting issues, such as unfavorable band offset, unsatisfactory electrical conductivity, low electron mobility, and high-density defects, remain in the TiO2 electron transport layer. In this work, yttrium (Y) is proposed as a dopant in the TiO2 electron transport layer. It is revealed that the incorporation of Y promotes the Fermi energy level of TiO2 shift upward, bringing about more favorable energy-level alignment for the transport of photogenerated carriers. In addition, the device assembled with a Y-TiO2 electron transport layer exhibits an increased built-in potential, suggesting a more powerful driving force for charge separation and transport. Eventually, the triple-cation perovskite solar cell equipped with a Y-TiO2 electron transport layer acquires an efficiency of 20.09%. It is superior to that of the TiO2-based device (17.28%). The results indicate that Y-ion doping is a promising method to fabricate highly efficient perovskite solar cells