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Image, graphical abstract Macrophage polarization is one of the main factors contributing to the proinflammatory milieu of transplanted islets. It causes significant islet loss. Bilirubin exhibits protective effects during the islet transplantation process, but the mode of delivering drugs along with the islet graft has not yet been developed. In addition, it remains unclear whether bilirubin or its derivatives can modulate macrophage polarization during islet transplantation. Therefore, this study aimed to develop an ε-polylysine-bilirubin conjugate (PLL-BR) to encapsulate the islets for protection and to explore its macrophage modulation activities. In in vitro studies, the PLL-BR was shown to tightly adhere to the islet surface. It also exhibited enhanced cytoprotective effects against oxidative and inflammatory conditions by promoting M2-type macrophage polarization. In i n vivo studies, the PLL-BR-protected islets successfully prolonged the euglycemia period in diabetic mice and accelerated the blood glucose clearance rate by maintaining the insulin secretion function. Compared to the untreated islets, the PLL-BR-encapsulated islets induced anti-inflammatory responses that were characterized by elevated levels of M2 macrophage markers and local vascularization. In conclusion, PLL-BR can be used as a tool for reprograming macrophage polarization while providing a more efficient immune protection for transplanted islets. Macrophage polarization is one main factor that caused significant loss of transplanted islets. Bilirubin possesses protective effects toward pancreatic islet, but how to deliver the drug along with the islet graft has not yet been harnessed. More importantly, whether bilirubin or its derivatives could modulate macrophage polarization during the host rejections has also not been answered. In this study, we developed an ε-polylysine-bilirubin conjugate (PLL-BR) to encapsulate the islets and explore its role in macrophage modulation activities. PLL-BR could attach to the surface of islets and exerted high oxidation resistance and anti-inflammatory effect. For the first time, we demonstrate that bilirubin and its derivatives effectively promoted the M2-type macrophage polarization, and optimize the immune microenvironment for islets survival and function. [ABSTRACT FROM AUTHOR]

One of the most important reasons for the controversy over the development of nuclear energy is the proper disposal of spent fuel. Separation of actinide and lanthanide ions is an important part of safe long-term storage of radioactive waste. Herein, a three-dimensional (3D) graphene-based macrostructure (GOCS) was utilized to remove actinide thorium and lanthanide europium ions from aqueous solutions. The adsorption of Eu(III) and Th(IV) on the GOCS was evaluated as a function of adsorption time, solution pH, initial ion concentrations, and ionic strength. The experimentally determined maximum adsorption capacities of this GOCS for Eu(III) (pH 6.0) and Th(IV) (pH 3.0) are as high as 150 and 220 mg/g, respectively. By using Fourier transformation infrared (FT-IR), X-ray photoelectron (XPS), and extended X-ray absorption fine structure (EXAFS) spectroscopy, we concluded that the Eu(III) and Th(IV) adsorption was predominantly attributed to the inner-sphere coordination with various oxygen- and nitrogen-containing functional groups on GOCS surfaces. Our selective adsorption results demonstrate that the actinide and lanthanide ions can be effectively separated from transition metal ions. This study provides new clues to the overall recycling of actinide and lanthanide ions in radioactive environmental pollution treatments. Image 1 • Adsorption capacities for Eu(III) and Th(IV) are as high as 150 mg/g at pH 6.0 and 220 mg/g at pH 3.0, respectively. • Highly selective adsorption of actinide and lanthanide ions from mixed solution could be realized under acidic conditions. • The inner-sphere surface complexation by -COO-, -OH, and -NH 2 was revealed by utilizing batch experiments and spectroscopy. The three-dimensional graphene-based GOCS macrostructure has a superior selective adsorption ability for lanthanide and actinide ions. [ABSTRACT FROM AUTHOR]

Flame stabilization mechanisms of a hydrogen-fueled laboratory model scramjet combustor are numerically studied. The combustor consists of a sonic fuel jet injected paralleling into a supersonic air flow at the base of a wedge-shaped strut. The numerical calculations are based on an Open Source Field Operation and Manipulation (OpenFOAM) solver using the large eddy simulation method. A skeletal mechanism for hydrogen-air chemistry including 9 species 27 reactions is used to depict the combustion dynamics. Three cases with air stagnation temperature of 568 K, 460 K, and 960 K, are respectively studied under the same equivalence ratio and entrance Mach number. Damköler number based on the subgrid turbulent mixing time scale and the instantaneous chemical time scale is used to distinguish the role of mixture self-igniting from flame propagation in different air inflows. Flame stabilization in such strut-based combustor is compared with that of cavity-based one. It is found that the basic working principles for the two types of combustor are similar. However, the strut shows more simplicity in flame stabilization locations. [ABSTRACT FROM AUTHOR]

This paper numerically investigated the dynamic characteristics of combustion in a model scramjet. Three-dimensional compressible large eddy simulation was performed on a hydrogen fueled combustor and pressure fluctuations were recorded. The analysis of pressure data showed that the combustion processes are intrinsically unstable under supersonic air inflow conditions. Flame dynamics were convinced by the fluctuations in flame lift-off distance away from the strut base. Combined with the corresponding time interval, instantaneous flame speed was calculated. Results indicated that pressure oscillations at different locations show difference in amplitude, frequency, and the underlying control mechanism. Flame front oscillation analysis showed that the flame–shock interaction in the strut recirculation zone was responsible for the combustion instability. Flame dynamics were compared with low-speed turbulent lifted flames. The transition between flame propagation just after the strut and shock-induced combustion in the subsonic bubble at the intersection of two wall-reflected oblique shocks made for the flame stabilization. [ABSTRACT FROM AUTHOR]

This study reports the combustion oscillation features in a three-dimensional (3D) rocket-based combined-cycle (RBCC) engine combustor under flight Mach number ( M flight ) 3.0 conditions both experimentally and numerically. Experiment is performed on a direct-connect ground test facility, which measures the wall pressure along the flow-path. High-speed imaging of the flame luminosity and schlieren is carried out at exit of the primary rocket. Compressible reactive large eddy simulation (LES) with reduced chemical kinetics of a surrogate model for kerosene is performed to further understand the combustion oscillation mechanisms in the combustor. LES results are validated with experimental data by the time-averaged and root mean square (RMS) pressure values, and show acceptable agreement. Effects of the primary rocket jet on pressure oscillation in the combustor are analyzed. Relation of the high speed rocket jet oscillation, which is thought to among the most probable sources of combustion oscillation, with the RBCC combustor is recognized. Results reveal that the unsteady over-expanded rocket jet has significant impacts on the combustion oscillation feature of the RBCC combustor, which is different from a thermo-acoustics type oscillation. The rocket jet/air inflow physical interactions under different rocket jet expansion degrees are experimentally studied. [ABSTRACT FROM AUTHOR]

This study reports combustion characteristics of a rocket-based combined-cycle engine combustor operating at ramjet mode numerically. Compressible large eddy simulation with liquid kerosene sprayed and vaporized is used to study the intrinsic unsteadiness of combustion in such a propulsion system. Results for the pressure oscillation amplitude and frequency in the combustor as well as the wall pressure distribution along the flow-path, are validated using experimental data, and they show acceptable agreement. Coupled with reduced chemical kinetics of kerosene, results are compared with the simultaneously obtained Reynolds–Averaged Navier–Stokes results, and show significant differences. A flow field analysis is also carried out for further study of the turbulent flame structures. Mixture fraction is used to determine the most probable flame location in the combustor at stoichiometric condition. Spatial distributions of the Takeno flame index, scalar dissipation rate, and heat release rate reveal that different combustion modes, such as premixed and non-premixed modes, coexisted at different sections of the combustor. The RBCC combustor is divided into different regions characterized by their non-uniform features. Flame stabilization mechanism, i.e., flame propagation or fuel auto-ignition, and their relative importance, is also determined at different regions in the combustor. [ABSTRACT FROM AUTHOR]

In this study, Large Eddy Simulation (LES) of supersonic turbulent mixing and combustion adopting a Partially Stirred Reactor (PaSR) sub-grid combustion model is performed for a hydrogen fueled model scramjet combustor. The compressible LES solver, which adopts a skeleton of 27 steps and 9 species hydrogen chemical kinetics model, is used to simulate the flowing and combustion processes based on structured hexahedral grids. The code is implemented in an Open Source Field Operation and Manipulation (OpenFOAM) solver, and validated against experimental data in terms of mean axial velocity and static temperature at different cross-sections, all show good predictions. An analysis of the flow field is carried out to investigate the supersonic turbulent flame structure and combustion mode in the combustor. Mixture fraction is extracted to indicate the reaction progress at different sites, which donates the most likely flame locations when at stoichiometric. Comparison of combustion parameters including OH mass fraction, scalar dissipation rate, flame index and heat release rate spatial distribution reveals that the supersonic combustion has the characteristics of a turbulent diffusion flame, where combustion is held at non-premixed mode controlled by turbulent mixing in the shear layers. A time scale analysis, the Damköhler Number is performed to examine these reactive zones in more detail. The role of auto-ignition in flame stabilization and lift-off is revealed. [ABSTRACT FROM AUTHOR]

Abstract: Design of an efficient site-specific drug delivery system based on degradable functional polymers still remains challenging. In this work, we synthesized and characterized three degradable functional polyesters belonging to the poly(malic acid) family: the poly(benzyl malate) (PMLABe), the poly(ethylene glycol)-b-poly(benzyl malate) (PEG42-b-PMLABe), the biotin-poly(ethylene glycol)-b-poly(benzyl malate) (Biot-PEG62-PMLABe). Starting from these building blocks, we were able to prepare the corresponding well-defined degradable functional nanoparticles whose toxicity was evaluated in vitro on normal and cancer cell lines. Results have evidenced that the prepared nanoparticles did not show any significant cytotoxicity even at high concentrations. A model anti-cancer drug (doxorubicin, Dox) or a fluorescent probe (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodicarbocyanine, DiD oil) has been encapsulated into PMLABe, PEG42-PMLABe or Biot-PEG62-PMLABe based nanoparticles in order to evaluate, respectively, the in vitro cytotoxicity of Dox-loaded nanoparticles on normal and cancer cell lines and the ligand (biotin) effect on cellular uptake in vitro using mmt 060562 cell line. Dox-loaded PMLABe, PEG42-PMLABe or Biot-PEG62-PMLABe nanoparticles showed an in vitro cytotoxicity similar to that of free Dox. Moreover, the DiD oil loaded Biot-PEG62-PMLABe based nanoparticles showed a better in vitro cellular uptake than ligand-free DiD oil loaded nanoparticles. Both results evidence the great potential of such degradable functional poly(malic acid) derivatives for the design of highly efficient site-specific anti-cancer nanovectors. [Copyright &y& Elsevier]

Transient mixing and ignition mechanisms in a simplified pre-chamber/main-chamber system are investigated using direct numerical simulation (DNS) with detailed chemical kinetics. Full ignition and flame propagation processes in the premixed methane/air mixtures are simulated. Ignition, the progress and topology of flame evolution, and the mean burning velocity in the main chamber are analyzed in detail. Four important phases in the ignition and flame propagation processes are identified based on the flame structure development in the main chamber, the pressure and velocity evolution at typical points in both the pre-chamber and main chamber. Results show that the intermediate species OH, CH 2 O, and HO 2 are critical for flame stabilization and propagation in the main chamber due to their high reactivity. This is sorted as the chemical effect that the pre-chamber jet acts on the main chamber. The high temperature jet also brings heat and unburned fuel into the main chamber, which are sorted as thermal and enrichment effect, respectively. The heat release rate is found to be approximately proportional to the product of CH 2 O and OH mass fractions, which could be regarded as a reliable and effective marker for the heat release rate of methane/air mixtures. It is found that the mean burning velocity in the main chamber can be elevated up to 30 times under the condition investigated. [ABSTRACT FROM AUTHOR]

Abstract The skin-friction in a rocket-based combined-cycle engine operating from Mach 1.5 to 6.0 was analyzed in the present study. The friction proportion of different parts of the engine was investigated to offer a reference for the rearrangement of skin-friction reduction in the engine. The distribution and variation trend of the skin-friction in the flow path as well as its impacts on the engine performance were numerically compared. At three typical flight points, i.e. at 1.8Ma, 3.0Ma and 6.0Ma, the change of the skin-friction with attack angle was studied. A special focus was placed on the reduction of the skin-friction by using boundary layer combustion. It was modeled when the airstream flowed into the engine at the speed of 6 Ma. The method of hydrogen combustion in boundary layer has achieved 57.7% skin-friction reduction effect. Highlights • The average value of skin-friction at 6 Ma is almost 4 times higher than at 1.5 Ma. • The skin-friction is as high as 40.3% of the thrust at 6 Ma. • The higher flight speed, the higher proportion of the skin-friction in combustor. • After 3 Ma, the skin-friction gradually increases with the increasing attack angle. • Drag is reduced by 57.5% on a simplified inlet through boundary layer combustion. [ABSTRACT FROM AUTHOR]

Intrauterine adhesion (IUA) is characterized by endometrial stromal replaced with fibrous tissue during the trauma or operation induced injury. Current clinic IUA management mainly involves surgical removal of the connective tissues and physical separation and often results in reoccurrence. It is of clinic interest to directly address the issue via facilitating the endometrial repair and thereby inhibiting the formation of re-adhesion. To this end, we designed a nanocomposite aloe/poloxamer hydrogel for β-estradiol (E2) intrauterine delivery to exert multi-therapeutic effects and promote endometrial regeneration for IUA treatment. Nanoparticulate decellularized uterus (uECMNPs) was prepared to encapsulate E2 (E2@uECMNPs), which improved the solubility and prolonged cargo release. Then, E2@uECMNPs were further embedded into the thermosensitive aloe-poloxamer hydrogel (E2@uECMNPs/AP). Multiple components from E2@uECMNPs/AP system could collectively promote proliferation and inhibit apoptosis of endometrial stromal cells. E2@uECMNPs/AP significantly increased morphological recovery and decreased uterine fibrosis rate compared with IUA rats in other groups in vivo. Additionally, the levels of Ki67, cytokeratin, and estrogen receptor β were all up-regulated, along with the decreased expression of TGF-β1 and TNF-α in the uterus from rats receiving E2@uECMNPs/AP therapy. Taken together, in situ administration of E2@uECMNPs/AP hydrogel could effectively promote endometrial regeneration and prevent the re-adhesion. Image, graphical abstract [ABSTRACT FROM AUTHOR]