Injectable and self-healing hydrogels with tissue adhesiveness and antibacterial activity as wound dressings for infected wound healing

The design of wound dressings with excellent self-healing ability, adequate adhesion, good biocompatibility, and potential antibacterial ability is of great significance for the healing of infected wounds arising from human activities. Herein, a series of multi-functional hydrogel dressings, poly(ionized isocyanoethyl methacrylate-glutamine)/poly(hexamethylene guanidine) (iG_x/PHMG_y) hydrogels, were obtained through homopolymerization of fully ionized isocyanoethyl methacrylate-glutamine (iIEM-Gln) in the presence of poly(hexamethylene guanidine) (PHMG), in which strong hydrogen bonds were formed among urea groups in the P (iIEM-Gln) chain to form a stable hydrogel network. The prepared iG_x/PHMG_y hydrogels exhibited adequate self-healing ability and tissue adhesion, which could be firmly adhered to the wound surface and remained intact during application. In addition, the presence of PHMG imparted good antibacterial activity to the hydrogels for the effective promotion of the wound healing in S. aureus infected skin wound on mice. Overall, this multi-functional hydrogel provides a facile and effective strategy for the design of infected wound dressings, and may show great potential in clinical applications.     

A Novel Ternary Composite of Polyurethane/Polyaniline/Nanosilica with Antistatic Property and Excellent Mechanical Strength: Preparation and Mechanism

Chinese Journal of Polymer Science - Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments. Herein, polyurethane was...     

Acridone-Based Host Materials for Green Phosphorescent and Thermally Activated Delayed Fluorescent OLEDs with Low-Efficiency Roll-Offs

By linking the carbazole unit to the nitrogen atom of acridone through phenyl or pyridyl, two compounds, named 10-(4-(9H-carbazol-9-yl)phenyl)acridin-9(10H)-one (AC-Ph-Cz) and 10-(5-(9H-carbazol-9-yl)pyridin-2-yl)acridin-9(10H)-one (AC-Py-Cz) were designed and synthesized. These two materials, characterized with highly twisted and rigid structure, good thermal stability, and balanced carrier-transporting properties, were employed as host materials for green phosphorescent and thermally activated delayed fluorescent organic light-emitting diodes (OLEDs). The carbazole group, despite its small contribution to the highest occupied molecular orbitals (HOMOs) of these two materials, plays an essential role as an intramolecular host in energy delivering and improving the hole transporting ability of these two hosts. The incorporation of the electron-deficient pyridyl group as a linking group slightly improves the electron transporting capability of AC-Py-Cz. The green phosphorescent OLED (PhOLED) based on AC-Py-Cz exhibited excellent device performance with a turn-on voltage of 2.5 V, a maximum power efficiency and an external quantum efficiency (η_ext) of 89.8 lm W⁻¹ and 25.2 %, respectively, benefitting from the better charge-balancing ability of AC-Py-Cz host due to the presence of the pyridyl bridge. More importantly, all the devices based on these two hosts showed low efficiency roll-off at high brightness due to the suppressed non-radiative transition in the emitting layer. In particular, the AC-Py-Cz-hosted green PhOLED exhibited an efficiency roll-off of 1.6 % from the maximum next at a high brightness of 1000 cd m⁻² and a roll-off of 15.9 % at an extremely high brightness of 10000 cd m⁻². This study manifests that acridone-based host materials have great potential in fabricating OLEDs with low efficiency roll-off.     

In situ confinement of iron-based active sites within high porosity carbon frameworks with enhanced activity for rechargeable Zn–air battery

Non-noble bifunctional electrocatalysts with robust activity and stability toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are greatly significant but challenging for Zn-air batteries. Here, in situ confinement of FeN_x active sites in high porosity carbon framework (FeN_x/CMCC) derived from chelate of carboxymethylcellulose (CMC) and iron ions were synthesized. Particularly, construction of FeN_x within porous carbon framework accelerates the electron transfer and the sufficient utilization of active centers, and then expedites the reaction kinetics of ORR and OER. As expected, the optimized FeN_x/CMCC exhibits superior ORR activity with a larger half-wave potential of 0.869 V. The rechargeable Zn-air battery delivers a higher power density of 99.6 mW/cm² and a special capacity of 781.9 mA h/g_Zn at 10 mA/cm², together with excellent durability of over 335 h. Remarkably, the as-assembled solid-state battery exhibits a higher open circuit voltage (OCV) of 1.5 V, a special capacity of 709.7 mA h/g_Zn, as well as prolonged cycling stability (90 h). Moreover, the flexible solid-state battery displays negligible loss of electrochemical performance under various bending angles, illustrating its potential application in flexible electronic devices.     

A Novel 3D Na(I) Coordination Polymer Constructed by 3,5-Bis(4'-Carboxy-Phenyl)-1,2,4-Triazole: Synthesis,Crystal Structure,and Photocatalytic Property

Crystallography Reports - A novel 3D metal coordination polymer, {[Na4(µ2-H2O)(DMF)2(BCT)2]?DMF}n (I) (DMF = N,N-dimethylformamide, H2BCT =...     

Effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid solution

In this study, the effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid (HCl) solution was investigated by using dodecyl trimethyl ammonium chloride (DTAC), tetradecyl trimethyl ammonium chloride (TTAC), cetyl trimethyl ammonium chloride (CTAC), and octadecyl trimethyl ammonium chloride (OTAC) as corrosion inhibitors to uncover their structure–efficiency relationships. The effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in HCl solution was studied under different conditions, such as corrosion inhibitor concentration, temperature, and acidity, and this was done using the weightlessness method. The results obtained show that these inhibitors have high corrosion inhibition effect on A₃ steel, and the corrosion inhibition efficiency is dependent on the length of the alkyl chain. At the same concentration, the longer the alkyl chain, the weaker the corrosion inhibition effect. When the temperature was 50 °C and the concentration of corrosion inhibitor was 70 mg/L, the corrosion inhibition efficiency order of the four cationic surfactants was DTAC > TTAC > CTAC > OTAC. Besides, the experimental results obtained show that the adsorption of the inhibitor on the A₃ steel surface conforms to the Langmuir type isotherm, and then the corresponding adsorption thermodynamic parameters were obtained according to these parameters. It was observed that ΔH, ΔS, and E_a increased with increase in the length of the alkyl chain. The adsorption of the inhibitor on the steel surface is an exothermic, spontaneous, entropy process.     

Chaos enhanced grey wolf optimization wrapped ELM for diagnosis of paraquat-poisoned patients

Paraquat (PQ) poisoning seriously harms the health of humanity. An effective diagnostic method for paraquat poisoned patients is a crucial concern. Nevertheless, it's difficult to identify the patients with low intake of PQ or delayed treatment. Here, a new efficient diagnostic approach to integrate machine learning and gas chromatography-mass spectrometry (GC–MS), named GEE, is proposed to identify the PQ poisoned patients. First, GC–MS provides the original data that efficiently identified the paraquat-poisoned patients. According to the high dimensionality of the original data, in the second stage, the chaos enhanced grey wolf optimization (EGWO) is adopted to search the optimal feature sets to improve the accuracy of identification. Finally, the extreme learning machine (ELM) is used to identify the PQ poisoned patients. To efficiently evaluate the proposed method, four measures were used in our experiments and comparisons were made with six other methods. The PQ-poisoned patients and robust volunteers can be well identified by GEE and the values of AUC, accuracy, sensitivity and specificity were 95.14%, 93.89%, 94.44% and 95.83%, respectively. Our experimental results demonstrated that GEE had better performance and might serve as a novel candidate diagnosis of PQ-poisoned patients.     

The effects of learning in production and group size on the lot-sizing problem

One of the lot-sizing problem extensions that received noticeable attention in the literature is the one that investigated the effects of learning in production. The studies along this line of research assumed learning to improve with the number of repetitions following a power form. There is evidence also that the group size, i.e., the number of workers learning in a group affects performance (time per unit). This note revisits the problem and modifies it by incorporating the group size, along with cumulative production, as a proxy for measuring performance. Numerical examples are provided to illustrate the behavior of the modified model. The results of the two models are also compared to draw some meaningful insights and conclusions. Although the results favor using a simple univariate learning curve, considering group size when modeling lot-sizing problems can significantly affect the unit production cost.     

A modified SPH method to model the coalescence of colliding non-Newtonian liquid droplets

This paper develops a modified smoothed particle hydrodynamics (SPH) method to model the coalescence of colliding non-Newtonian liquid droplets. In the present SPH, a van der Waals (vdW) equation of state is particularly used to represent the gas-to-liquid phase transition similar to that of a real fluid. To remove the unphysical behavior of the particle clustering, also known as tensile instability, an optimized particle shifting technique is implemented in the simulations. To validate the numerical method, the formation of a Newtonian vdW droplet is first tested, and it clearly demonstrates that the tensile instability can be effectively removed. The method is then extended to simulate the head-on binary collision of vdW liquid droplets. Both Newtonian and non-Newtonian fluid flows are considered. The effect of Reynolds number on the coalescence process of droplets is analyzed. It is observed that the time up to the completion of the first oscillation period does not always increase as the Reynolds number increases. Results for the off-center binary collision of non-Newtonian vdW liquid droplets are lastly presented. All the results enrich the simulations of the droplet dynamics and deepen understandings of flow physics. Also, the present SPH is able to model the coalescence of colliding non-Newtonian liquid droplets without tensile instability.     

Multi-stable quantum droplets in optical lattices

Nonlinear Dynamics - We address the nonlinear dynamics of binary Bose-Einstein condensates with mutually symmetric spinor components trapped in an optical lattice. The interaction between the...