pH-responsive bioadhesive with robust and stable wet adhesion for gastric ulcer healing.

Development of bioadhesives that can be facilely delivered by endoscope and exhibit instant and robust adhesion with gastric tissues to promote gastric ulcer healing remains challenging. In this study, an advanced bioadhesive is prepared through free radical polymerization of ionized N-acryloyl phenylalanine (iAPA) and N-[tris (hydroxymethyl) methyl] acrylamide (THMA). The precursory polymer solution exhibits low viscosity with the capability for endoscope delivery, and the hydrophilic-hydrophobic transition of iAPA upon exposure to gastric acid can trigger gelation through phenyl groups assisted multiple hydrogen bonds formation and repel water molecules on tissue surface to establish favorable environment for interfacial interactions between THMA and functional groups on tissues. The in-situ formed hydrogel features excellent stability in acid environment (14 days) and exhibits firm wet adhesion to gastric tissue (33.4 kPa), which can efficiently protect the wound from the stimulation of gastric acid and pepsin. In vivo studies reveal that the bioadhesive can accelerate the healing of ulcers by inhibiting inflammation and promoting capillary formation in the acetic acid-induced gastric ulcer model in rats. Our work may provide an effective solution for the treatment of gastric ulcers clinically.

Numerical Simulation on Erosion and Stress on a Small-Diameter Hydrajet Fracturing Tool.

Conventional hydrajet fracturing techniques are often frustrated when they are applied to some specific well types, such as casing-damaged and small-diameter wells. It is of great significance to investigate the erosion and stress on a small-diameter hydrajet fracturing tool during its service and clarify the relevant influencing factors. Based on the solid-liquid two-phase flow theory and erosion model, a numerical simulation was conducted on the erosion and stress on a small-diameter hydrajet fracturing tool by using the computational fluid dynamics approach in order to understand how the inlet flow rate, particle size, and particle mass concentration affect the erosion and stress on the tool. The results show that the erosion on the small-diameter hydrajet fracturing tool is generally a cutting erosion of proppant particles on the tool body. Such erosion occurs on the lower wall of the nozzle, and the erosion at the upper-0° nozzle is higher in rate and smaller in area than that at the lower-180° nozzle. The maximum stress of the small-diameter hydrajet fracturing tool is concentrated on the upper and lower walls of the upper and lower nozzles, especially the lower part inside the upper nozzle. The maximum erosion rate, average erosion rate, and maximum stress on the wall near the nozzle during fracturing increase as the inlet flow rate and particle mass concentration increase and decrease as the proppant particle size increases.

Hydrogen Bonds Reinforced Ionogels with High Sensitivity and Stable Autonomous Adhesion as Versatile Ionic Skins.

Flexible wearable sensors have demonstrated enormous potential in various fields such as human health monitoring, soft robotics, and motion detection. Among them, sensors based on ionogels have garnered significant attention due to their wide range of applications. However, the fabrication of ionogels with high sensitivity and stable autonomous adhesion remains a challenge, thereby limiting their potential applications. Herein, we present an advanced ionogel (PACG-MBAA) with exceptional performances based on multiple hydrogen bonds, which is fabricated through one-step radical polymerization of N-acryloylglycine (ACG) in 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES) in the presence of N,N'-methylenebis(acrylamide) (MBAA). Compared with the ionogel (PAA-MBAA) formed by polymerization of acrylic acid (AA) in EMIES, the resulting ionogel exhibits tunable mechanical strength (35-130 kPa) and Young's modulus comparable to human skin (60-70 kPa) owing to the multiple hydrogen bonds formation. Importantly, they demonstrate stable autonomous adhesion to various substrates and good self-healing capabilities. Furthermore, the ionogel-based sensor shows high sensitivity (with a gauge factor up to 6.16 in the tensile range of 300-700%), enabling the detection of both gross and subtle movements in daily human activities. By integration of the International Morse code, the ionogel-based sensor enables the encryption, decryption, and transmission of information, thus expanding its application prospects.

Molecular architecture regulation for the design of instant and robust underwater adhesives.

Development of underwater adhesives with instant and robust adhesion to diverse substrates remains challenging. A strategy taking the structural advantage of phenylalanine derivative, N-acryloyl phenylalanine (APA), is proposed to facilely prepare a series of underwater polymeric glue-type adhesives (UPGAs) through one-pot radical polymerization with commonly used hydrophilic vinyl monomers. The adjacent phenyl and carboxyl groups in APA realize the synergy between interfacial interactions and cohesion strength, by which the UPGAs could achieve instant (~5 seconds) and robust wet tissue adhesion strength (173 kilopascal). The polymers with varied hydrophobicity and substitutional groups as well as carboxyl and phenyl groups in separated components are designed to investigate the underwater adhesion mechanism. The universality of APA for the construction of UPGAs is also verified by the copolymerization with different hydrophilic monomers, and the applications of the UPGAs have been validated in diverse hemorrhage models and distinct substrates. Our work may give a promising solution to design potent underwater adhesives.

Nanocomposite conductive hydrogels with Robust elasticity and multifunctional responsiveness for flexible sensing and wound monitoring.

Flexible biosensors made from conductive hydrogels have shown tremendous potential in health management and human-machine interfaces. Nevertheless, it remains challenging to fabricate conductive hydrogels with robust resilience and long-term stability. Herein, we report a nanocomposite conductive hydrogel prepared through one-pot radical polymerization of 3-acrylamidophenylboronic acid (APBA) and acrylamide (AM) in the presence of LAPONITE® XLG nanosheet (XLG) stabilized carbon nanotubes (CNTs). Owing to the existence of various non-covalent interactions within the network (B-N coordination, hydrogen bond, and polymer chain entanglement), the hydrogels feature splendid mechanical properties with a tensile strength of 252-323 kPa, fracture strain of 880-1200%, Young's modulus of 48-50 kPa and fracture energy of 911-1078 J m-2, and exhibit robust elasticity and fatigue resistance during 1000 consecutive tensile and compressive cycles. The hydrogels show remarkable sensing performances (gauge factor up to 9.43) and a broad sensing range of strain (1-300%) and pressure (1-80 kPa), enabling reliable and accurate monitoring of large and tiny motions in daily human life. Moreover, the conductive hydrogels could not only accelerate skin incision healing but also act as smart wearable sensors to monitor the skin wound healing process by detection of local temperature changes.

Toughening Double-Network Hydrogels by Polyelectrolytes.

The Hoffmeister effect of inorganic salts is verified as a promising way to toughen hydrogels, however, the high concentration of inorganic salts may be accompanied by poor biocompatibility. In this work, it is found that polyelectrolytes can obviously elevate the mechanical performances of hydrogels through the Hoffmeister effect. The introduction of anionic poly(sodium acrylate) into poly(vinyl alcohol) (PVA) hydrogel induces the aggregation and crystallization of the PVA to boost the mechanical properties of the resulting double-network hydrogel: elevation of 73, 64, 28, 135, and 19 times in the tensile strength, compressive strength, Young's modulus, toughness, and fracture energy compared with poly(acrylic acid), respectively. It is noteworthy that the mechanical performances of the hydrogels can be flexibly tuned by the variation of polyelectrolyte concentration, ionization degree, relative hydrophobicity of the ionic component, and polyelectrolyte type in a wide range. This strategy is verified to work for other Hoffmeister-effect-sensitive polymers and polyelectrolytes. Also, the introduction of urea bonds into the polyelectrolyte can further improve the mechanical properties and antiswelling capability of hydrogels. As a biomedical patch, the advanced hydrogel can efficiently inhibit hernia formation and promote the regeneration of soft tissues in an abdominal wall defect model.

Electrocatalytic desalination with CO2 reduction and O2 evolution.

Multifunctional electrocatalytic desalination is a promising method to increase the production of additional valuable chemicals during the desalination process. In this work, a multifunctional desalination device was demonstrated to effectively desalinate brackish water (15 000 ppm) to 9 ppm while generating formate from captured CO2 at the Bi nanoparticle cathode and releasing oxygen at the Ir/C anode. The salt feed channel is sandwiched between two electrode chambers and separated by ion-exchange membranes. The electrocatalytic process accelerates the transportation of sodium ions and chloride ions in the brine to the cathode and anode chamber, respectively. The fastest salt removal rate to date was obtained, reaching up to 228.41 µg cm-2 min-1 with a removal efficiency of 99.94%. The influences of applied potential and the concentrations of salt feed and electrolyte were investigated in detail. The current research provides a new route towards an electrochemical desalination system.

Achieving High-Quality Freshwater from a Self-Sustainable Integrated Solar Redox-Flow Desalination Device.

Solar-assisted electrochemical desalination has offered a new energy-water nexus technology for sustainable development in recent studies. However, only a few reports have demonstrated insufficient photocurrent, a low salt removal rate, and poor stability. In this study, a high-quality freshwater level of 5-10 ppm (from an initial feed of 10 000 ppm), an enhanced salt removal rate (217.8 µg cm-2 min-1 of NaCl), and improved cycling and long-term stability are achieved by integrating dye-sensitized solar cells (DSSCs) and redox-flow desalination (RFD) under light irradiation without additional electrical energy consumption. The DSSC redox electrolyte (I- /I3- ) is circulated between the photoanode (N719/TiO2 ) and intermediate electrode (graphite paper). Two DSSCs in parallel or series connections are directly coupled to the RFD device. Overall, this hybrid system can be used to boost photo electrochemical desalination technology. The energy-water nexus technology will open a new route for dual-role devices with photodesalination functions without energy consumption and solar-to-electricity generation.

Bi metal/oxygen-deficient BiO2-x with tetrahedral morphology and high photocatalytic activity.

Vacancy-rich materials with high photocatalytic activity are of great interest for pollutants removal and play a significant role in green chemistry. Herein, we successfully synthesized Bi/BiO2-x composite through hydrothermal route. In this case, the surface plasmon resonance effect of Bi and oxygen vacancies of BiO2-x collectively increase the removal rate of pollutants. More importantly, the Bi/BiO2-x composites have enhanced activity in the degradation of RhB, MO, BPA and CIP, and the reduction of Cr(VI) and PNA. Besides, an enhanced photocatalytic activity is due to the main reactive species of ·[Formula: see text] and h+ that is confirmed by trapping experiments and ESR analyses. The electronic structure and visible light harvesting of photocatalysts were measured and also theoretically calculated by using density functional theory and finite difference time domain calculations, DRS, VB x-ray photoelectron spectroscopy and Mott-Schottky plots, which allowed to propose a possible photocatalytic mechanism for the degradation process.

Enhanced Efficiency of Air-Stable CsPbBr3 Perovskite Solar Cells by Defect Dual Passivation and Grain Size Enlargement with a Multifunctional Additive.

The perovskite solar cells (PSCs) based on cesium lead bromide (CsPbBr3) with outstanding environmental stability and low preparation cost are regarded as one of the most promising photovoltaic devices for commercial applications. However, the performance of CsPbBr3 PSCs can be badly deteriorated by the intense charge recombination arising from the ionic defects at the grain boundaries of perovskite film. To cope with this issue, we adopt an amino acid of l-lysine with two amino and one carboxyl groups as a chemical additive to incorporate into perovskite film to simultaneously anchor the uncoordinated Pb2+ (Cs+) and halogen ion defects. Further, the grain size of CsPbBr3 perovskite is boosted from 688 to over 1000 nm after l-lysine incorporation as a result of the decreased nucleation rate and the sufficient growth of perovskite, which effectively reduce the grain boundaries for load defects. As expected, the optimized device achieves a best power conversion efficiency of 9.69% attributed to the remarkably reduced charge recombination and enhanced charge extraction arising from the efficient defects dual-passivation and enlarged grain size of perovskite film as well as the improved energy level alignment at the device interface after the introduction of l-lysine, which is elevated by 61.23% in comparison to 6.01% efficiency of the pristine one. Moreover, the unencapsulated device with l-lysine incorporation exhibits remarkable long-term stability in air with 80% RH at 25 °C and 0% RH at 80 °C as well as under continuous illumination conditions. This work provides an effective multifunctional additive for imperfection passivation and grain size enlargement of perovskite to build PSCs with high efficiency and stability.

Co3O4-NP embedded mesoporous carbon rod with enhanced electrocatalytic conversion in lithium-sulfur battery.

Lithium-sulfur battery has been considered to be one of the promising alternatives to the traditional lithium-ion battery due to its high theoretical energy density and saving-cost. However, the sluggish reaction during the decomposition of lithium sulfide results in a low specific capacity and poor cycling stability. Herein Co3O4 nano-particle embedded mesoporous carbon rod (Co3O4@MCR) was prepared through a template method to accommodate sulfur as cathode of lithium-sulfur battery. The resultant composite was characterized by Raman spectra, XRD, TEM, SEM, etc. The electrochemical investigation demonstrated that Co3O4@MCR composite exhibits enhanced electrocatalytic performance in lithium-sulfur battery, which was confirmed by cyclic voltammograms, galvanostatic charge-discharge testing, and study of sulfide oxidation using linear sweep voltammetry. With the current density of 0.2 A/g, the specific discharge capacity can be achieved up to more than 1000 mAh/g after 100 cycles. The enhanced electrocatalytic conversion from Co3O4@MCR leads to a low over-potential, fast lithium-ion kinetics and sulfide oxidation reaction.