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Acute liver failure (ALF) is a life-threatening disease that occurs secondary to drug toxicity, infection or a devastating immune response. Orthotopic liver transplantation is an effective treatment but limited by the shortage of donor organs, the requirement for life-long immune suppression and surgical challenges. Stem cell transplantation is a promising alternative therapy for fulminant liver failure owing to the immunomodulatory abilities of stem cells. Here, we report that when transplanted into the liver, human endoderm stem cells (hEnSCs) that are germ layer-specific and nontumorigenic cells derived from pluripotent stem cells are able to effectively ameliorate hepatic injury in multiple rodent and swine drug-induced ALF models. We demonstrate that hEnSCs tune the local immune microenvironment by skewing macrophages/Kupffer cells towards an anti-inflammatory state and by reducing the infiltrating monocytes/macrophages and inflammatory T helper cells. Single-cell transcriptomic analyses of infiltrating and resident monocytes/macrophages isolated from animal livers revealed dramatic changes, including changes in gene expression that correlated with the change of activation states, and dynamic population heterogeneity among these cells after hEnSC transplantation. We further demonstrate that hEnSCs modulate the activation state of macrophages/Kupffer cells via cystatin SN (CST1)-mediated inhibition of interferon signaling and therefore highlight CST1 as a candidate therapeutic agent for diseases that involve over-activation of interferons. We propose that hEnSC transplantation represents a novel and powerful cell therapeutic treatment for ALF.

This study presents the preparation of cellulose micro-nanofibrils (CMNFs) from Enteromorpha (EP) and the application in PVA/acetylated distarch phosphate (ADSP)/CMNFs composite films. The Micro-nano scale, hydrophilicity, and strong hydrogen bond characteristics of CMNFs prepared form EP by acid hydrolysis were confirmed through the granular statistics, XRD analysis and chemical structure analysis. With the addition of CMNFs, the ultimate tensile strength and elongation at break of composite films are increased by 42.4 % and 90.3 %. An original Weibull statistical analysis shows the impact of CMNFs' added amount on strength distribution and ultimate stress. SEM and polarizing microscope images show the CMNFs' dispersion state in that films is optimal, when their addition was to be 2 %-3 % of total dry weight of PVA/ADSP matrix， which is consistent with the results of Weibull modulus analysis. The main thermal weight-loss process of the composite film is divided into four stages, CMNFs can significantly increase the thermostability at 280 °C to 400 °C. The experiment of water contact angle and water vapor transmission rate of the composite films confirmed that CMNFs can improve films' hydrophilicity. This study provides basis for the preparation of hydrophilic CMNFs and mechanism of modification study PVA-based composites.

Thin-rim gears are widely used in industrial fields such as aerospace and electric vehicles due to the advantage of light weight. Yet, the root crack fracture failure of thin-rim gears significantly limits their application and further affects the reliability and safety of high-end equipment. In this work, the root crack propagation behavior of thin-rim gears is experimentally and numerically investigated. The crack initiation position and crack propagation path for different backup ratio gears are simulated using gear finite element (FE) models. The crack initiation position is determined using the maximum gear root stress position. An extended FE method coupled with commercial software ABAQUS is used to simulate the gear root crack propagation. The simulation results are then verified by conducting experimental tests for different backup ratio gears based on a dedicated designed single-tooth bending test device.

A new fluorescent sensor dicyanoisophorone rhodanine-3-acetic acid has been developed by employing a DCI-based push–pull dye as the fluorophore and RDA as the recognition moiety for the simultaneous sensing of Fe3+ and Hg2+.

Herein, a self-healing hybrid polyurethane acrylate was prepared by solution polymerization of acrylic monomers in the presence of preformed polyurethane chains containing aliphatic disulfide bonds with terminal isocyanate groups.

Purpose The silicone modifications of two-component epoxy resin coatings are commonly built on epoxy resins rather than on epoxy curing agents. The silicone-modified epoxy curing agent system is rarely reported yet. This study aims to prepare the polysiloxane (PS)-modified waterborne epoxy coatings based on aqueous curing agents technology. Design/methodology/approach Waterborne epoxy curing agents with different contents of terminal epoxy PS were synthesized by reacting with triethylenetetramine, followed by incorporating of epoxy resin (NPEL-128) and polyethylene glycol diglycidyl ether. The waterborne epoxy coatings were prepared with the above curing agents, and their performance was investigated through thermogravimetric analysis, scanning electron microscopy, mechanical characterization, gloss measurement, chemical resistance test and ultraviolet (UV) aging experiment. Findings The results showed that the epoxy coating prepared by silicon-modified curing agent has higher gloss, better chemical resistance and UV resistance than the coating from unmodified curing agent with terminal epoxy PS and commercially available waterborne epoxy curing agent (Aradur 3986), as well as the competitive mechanical properties and heat resistance. Reduced water absorption on fibrous paper was also obtained with the help of silicon-modified curing agent. Originality/value These findings will be valuable for resin researchers in addressing the modification issues about waterborne epoxy resin and curing agent.

Self-healing polymers based on dynamic crosslinkers have drawn rapidly increasing interest over the last decade. Here, a self-healable epoxy network with exchangeable disulfide bonds was synthesized by polymerizing two epoxies with an aromatic amine containing a disulfide bond. The bisphenol A diglycidyl ether (DGEBA) and poly(ethylene glycol) diglycidyl ether (DER736) were used as rigid and soft components, respectively. The crosslinking densities of studied polymers decreased with the increasing amount of DER736, resulting in the lower glassy temperature and weaker mechanical strength. The dynamic covalent network character of disulfide bond and its low active energy were also investigated through stress relaxation experiments at various temperatures. The self-healing performance of healable epoxy resins with varied flexibility was measured by tensile tests. The tensile strength of a full-cut sample was restored to 84% (13 MPa) of the initial values (16 MPa) at moderate temperature. Its healed fracture strain was up to 505%. Moreover, the effect of healing time and temperature on the self-healing properties was also studied. A model was proposed to investigate the self-repairing efficiency evolution with healing time, suggesting that hydrogen bonds mainly contributed to the initial sticking or interfacial adhesion while disulfide links and chain interdiffusion assisted time dependent reformation of networks to restore the original mechanical strength.

Development of a novel fluorescence enhancement probe for detection of Sn2+ in organisms, with high selectivity and sensitivity, is of great interest but remains a great challenge. Herein, an ICT-based fluorescence probe TPPB was rationally developed to act as an ‘enhancement’ luminescent and “naked-eye” indicator for Sn2+ detection. Importantly, spectroscopic studies indicated that TPPB was a fluorescence enhancement sensor for Sn2+ with rapid response, low detection limit (0.116 μM) and excellent binding constant (1.6 × 104 M−1). The mechanism of TPPB response to Sn2+ was further proved by 1H NMR titration, and enhancement calculations. Furthermore, TPPB is applied as a fluorescence probe for imaging in Hela cells, indicated that it can be potentially applied for Sn2+ sensing in biological fields.

In this paper, large-scale, self-standing polypyrrole/graphene oxide (PPy/GO) nanocomposite films were prepared by an environmentally friendly and easy-to-operate confined polymerization method, and were also assembled as electrode materials for symmetric all-solid-state supercapacitors. In this paper, large-scale, self-standing polypyrrole/graphene oxide (PPy/GO) nanocomposite films were prepared by an environmentally friendly and easy-to-operate confined polymerization method, and were also assembled as electrode materials for symmetric all-solid-state supercapacitors. The morphology, chemical structure and electrochemical property were characterized by field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS), respectively. The lamellar structure of GO and both strong interaction with ice and pyrrole could promote polymerization of pyrrole and improve the compactness of the film. With the aid of GO, the conjugation length of PPy increased, the resistance of the material decreased, and the electrochemical energy storage of the composite film was significantly enhanced. In the case of 2.5 wt% GO, the prepared PPy/GO nanocomposite supercapacitor exhibited a high area specific capacitance of 97.3 mF cm−2 at 1 mA cm−2. Furthermore, the PPy/GO film supercapacitor also showed excellent cycling stability and good flexibility.

Polyaniline (PANI)/Epoxy copolymer as a core material was synthesized via a chemical oxidation method. Various analytical techniques, including scanning electron microscope, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, thermogravimetry, and electrochemical impedance spectroscopy, were used to characterize the morphology, compositions, and self-healing and anticorrosion properties of the prepared microcapsules and coatings. The prepared PANI/Epoxy copolymer showed the best electrochemical corrosion resistance when the ratio of PANI to epoxy was 0.05: 1 (wt.:wt.). For the mass fraction of the core (PANI/Epoxy copolymer) of 60.84 ± 0.06 wt%, the mean particle diameter of the prepared microcapsules was 4.20 ± 0.92 μm. The coatings with 15 wt% microcapsules possessed excellent self-healing performance and corrosion resistance. The low-frequency impedance modulus at 0.01 Hz of scratched coatings immersed in the NaCl solution for 24 h was 5.27 × 10

Photoacoustic (PA) imaging has received more and more attention on disease diagnosis and fundamental scientific research. It is still challenging to amplify their imaging ability and reduce the toxicity of inorganic materials and exogenous contrast agents. Semiconducting polymer nanoparticles (SPNs), as a new type of contrast agent, have the advantages of low toxicity, flexible structure adjustment, good photostability, and excellent photothermal conversion efficiency. SPNs containing benzo(1,2-c;4,5-c′)bis(1,2,5)thiadiazole (BBT) units, as the most classic second near-infrared window (NIR-II, 1,000–1700 nm) PA contrast agents, can achieve light absorption in the NIR-II region, thereby effectively reducing light loss in biological tissues and improving imaging resolution. This mini review summarizes the recent advances in the design strategy of BBT and its derivative-based semiconducting polymer nanoparticles for second near-infrared photoacoustic imaging. The evolution process of BBT blocks provides a unique perspective for the design of high-performance NIR-II PA contrast agents.

The hexamethylenediamine-modified graphite oxide/Co-polyamide (GO-HMD/CO-PA) nanocomposites were successfully produced by solution blending method. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy analyses revealed that GO with a large number of oxygen-containing functional groups was successfully obtained by a modified Hummer’s method. For GO-HMD, the amino and amide bonds were introduced into the GO sheets, making the sheets more incompact, fluffy, and irregular. GO-HMD with a content of less than 1 wt% could be uniformly dispersed in the CO-PA matrix. A series of analysis indicated that the tensile strength, yield strength, and elongation at break of 0.4 wt% GO-HMD/CO-PA increased by 73.4%, 185.9%, and 42.3%, respectively. Thermogravimetric analysis showed that GO-HMD played the role of the heterogeneous nucleation in the matrix and could change the crystal type of the polyamide. The T 50% and Td , max of nanocomposites were 14.3°C and 11.8°C higher than pure polyamide, respectively. The nanofiller GO-HMD contributes to the increase of the thermal diffusivity at low temperature.

Ba0.7Sr0.3TiO3 ceramics has been synthesized by solid state reaction method. The effects of sintering time on microstructure and electric properties of Ba0.7Sr0.3TiO3 ceramics have been investigate...

The fatigue failures of gears have great influence on lifetime and reliabilities of mechanical transmissions. Initial residual stress (IRS) induced in the manufacturing process, together with the applied loading stress, contributes to gear fatigue behavior. Gear fatigue behavior represents a continuous damaging process during a high-cycle period. In the present work, a damage-coupled numerical model considering the effect of IRS is developed to investigate the gear fatigue performance. The deterioration of gear material, the detailed evolution of damage and the stress response during the cyclic loading process are calculated and recorded based on the continuum damage mechanics (CDM) using a user material subroutine (UMAT) in ABAQUS. Both the tooth surface contact fatigue and tooth root bending fatigue of the gear are evaluated, and the influence of IRS on stress response and damage evolution is analyzed. Results show that the risk of surface contact fatigue failure of this gear is much greater than that of the tooth bending fatigue. The initial compressive residual stress has positive effect on contact fatigue performance while the initial tensile residual stress with amplitude of 380 MPa would reduce the gear contact fatigue life by 20%.

Contact fatigue failures of gears, especially those used in heavy duty conditions such as wind turbine gears, become important issues in mechanical transmission industry. In the present work, a continuous damage mechanism and Voronoi-based finite element model is developed to investigate the contact fatigue of a wind turbine gear. Plane strain assumption is adopted to simplify the gear contact model. Voronoi tessellations are utilized to represent the microstructure topology of the gear material, and continuous damage mechanism is implemented to reflect the material degradation within critical substrate area. With the developed framework, the contact pressure distribution, intergranular mechanical response and the progressive fatigue damage at the grain boundaries during repeated gear meshing are evaluated and discussed in detail. The depths of the maximum shear stress reversal and the crack initiation agree well with previously reported findings. The influence of microstructure on the gear contact fatigue behavior is also investigated.

The fibers obtained by centrifugal melt electrospinning exhibit high production efficiency, controllable morphology, and excellent mechanical properties. Therefore, centrifugal electrospinning technology is in alignment with the industrial development trend of superfine fiber preparation. However, during the rapid development of this new spin method, some fundamental understanding of the relationships between the fiber performance and centrifugal force, electric field force, and gravity is unclear. In this study, the effect of the spin factors on the fiber properties (diameter, yield, and molecular chain formation) is investigated by dissipative particle dynamics simulation. The results show that in an electrostatic field, if the rotating speed, temperature, and electric field intensity increases, the fiber diameter decreases, and fiber productivity and chain length increase. In a pulsed electric field, the fiber diameter is very small when the duty ratio is 70% and the chain length is long when the duty ratio is 100%. However, as the frequency increases, the fiber diameter decreases sharply, whereas the chain length increases gradually. When the fiber drops rapidly, the chain length generally becomes longer with increasing steps. The above knowledge of the fiber performance and spin factors will contribute significantly to obtain high-quality fibers using centrifugal melt electrospinning.

Fe-Co nanoparticle-incorporated carbon nanofibers ((Fe-Co)-CNFs) were obtained by a simple and flexible electrospinning method and were further pre-oxidized and carbonized under a high-temperature nitrogen atmosphere for application as counter electrodes for highly efficient platinum-free dye-sensitized solar cells (DSSCs). Electrochemical characterizations revealed that the (Fe-Co)-CNFs showed excellent electrocatalytic activity for the I3−/I− redox couple. Photoelectric performance tests have shown that dye-sensitized solar cells equipped with (Fe-Co)-CNF counter electrodes have comparable photovoltaic efficiency to platinum counter electrode cells. This is because the graphite properties of these fibers rendered them electronically conducting. One-dimensional nanofibers provide oriented electron transport pathways, while lapped fibers form a three-dimensional mesoporous network, enhancing the contact with the electrolyte, and hence leading to faster ionic reaction kinetics. This study demonstrates that (Fe-Co)-CNFs can be used as low-cost high-efficiency counter electrodes for DSSCs.

Under the action of the wind, wind turbine gears experience complex loading histories in which the amplitude of the load is varying. The variable load conditions make the load sequence and the load amplitude inverse number as important factors to be considered for gear fatigue analysis. In the present work, a damage-coupled elastic-plastic constitutive model based on the continuous damage mechanics (CDM) is established to analyze the influence of load sequence on rolling contact fatigue (RCF) crack initiation of a wind turbine gear. The crack initiation is indicated by reaching the critical threshold of the defined damage variable related to the shear stress range and the plastic strain. During repeated loading cycles, the deterioration of material is reflected by gradually reducing mechanical properties. The numerical simulation is carried out in the frame of ABAQUS using the subroutine of user defined material subroutine (UMAT). The two-level load conditions are selected and results of which are compared with those of constant amplitude load conditions. Different inverse numbers are utilized to investigate the influence of load amplitude inverse number on crack initiation life. Simulation results are compared with existing damage accumulation criteria. The results indicate that when the first crack initiates, the sum of lifetime ratio is greater than unity for the low-high load sequence, while this value is less than unity for the high-low load sequence. Furthermore, the increase of the load amplitude inverse number will weaken the influence of the load sequence with regard to the crack initiation life. The highly nonlinear characteristic of damage accumulation during fatigue process under variable loading histories is captured by the proposed method. This method provides a new way to reveal the contact fatigue process of gears under variable loading histories and lay a foundation for predicting the accurate fatigue life under the real, complex loading condition of a gear.