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• The evolution law of fatigue damage of NEPE propellants is analyzed based on tests. • The generation mechanism of typical low-frequency fatigue behaviors is discussed. • An improved FDZM is proposed for predicting the fatigue behavior of NEPE propellants. The long-term fatigue loading history from offshore vibration environment will cause microdamage and affect the mechanical properties of NEPE solid propellant grains. The paper investigates the evolution law of microdamage through constant-strain-amplitude fatigue tests, and proposes an improved fractional derivative constitutive model for effectively predicting the low-frequency fatigue behavior of NEPE solid propellant based on the experimental phenomena. The evolution law of microdamage is negative power functional with the loading time and exponential with the maximum loading strain during the fatigue loading process. The stress-softening behavior, the Mullins effect, and the accumulation of residual strain are observed, as characteristics of low-frequency fatigue behavior. The theoretical modeling of the stress-softening behavior and the Mullins effect is proven to be significant for effectively predicting the low-frequency fatigue behavior by the improved fractional derivative constitutive model, while strain-modfication is also necessary for eliminating the influence of residual strain. The fatigue damage in solid propellant grains cannot be neglected when assessing the structural integrity of a solid propellant grain which has experienced long-term transportation or offshore storage. [ABSTRACT FROM AUTHOR]

Achieving high catalytic performance with the lowest cost is critical for hydrogen evolution reduction. In recent years, biomass-derived carbon catalysts have triggered huge interest in catalytic reactions owing to the low cost, high energy conversion efficiency and environmental friendliness. A rapid growth of novel electrocatalysts is witnessed especially those based on non-precious metals, some of which approach the activity of precious metals. Synergistic interactions between metals and heteroatoms can significantly improve the electrocatalytic activity, thus transition metal-decorated biomass-based carbon materials were commonly adopted to improve HER performance. The resulting electrocatalytic activities are introduced and compared to conventional Pt/C-based electrocatalysts in present research. Moreover, the remaining challenges in the development process and future prospects of hydrogen evolution reduction catalysts are discussed. • The advantages, synthetic methods of biomass-based catalysts for HER were summarized. • The transition metals in different forms can promote the electrocatalytic activity. • The challenges in the development process and future prospects were discussed. [ABSTRACT FROM AUTHOR]

Understanding the dopant behavior in cement clinker has been an important issue due to the increasing use of alternative fuels and secondary raw materials for cement manufacturing following the rising demand for reduction of CO 2 emissions and energy consumption. In this work, state-of-the-art ab initio calculations have been employed to systematically investigate manganese (Mn) doping mechanism in four dominant clinker phases. Corresponding experimental studies are incorporated to verify simulated results. A conspicuous preference of Mn for occupying the Fe site in ferrite is found based on formation energy analyses, which is in accord with our experiments and vast literatures. More in-depth analyses indicate the Mn doping mechanism follows the “electronic structure matching” principle, which influences the stability of doped structures by inducing localized coordination distortions. The work provides a fundamental perspective to investigate doped clinker, which facilitates the searching for other doping species, thereby designing steerable doping-enhanced cement. [ABSTRACT FROM AUTHOR]

Ba x Sr 1− x TiO 3 –(Ba–B–Al–Si–O) glass ceramics (BST–BBAS) was prepared via controlled crystallization. The effect of the crystallization temperature on the electric properties of BST–BBAS glass ceramics were investigated. The results show that the BDS first increases with the crystallization temperature rising until the maximum and then changes to decrease. In order to get higher energy storage materials, the microwave treatment was introduced to this study. It was found that microwave treatment restrain the formation of the dendritic microstructure, so that improve the dielectric breakdown strength (BDS) (increased from 1166 kV/cm to 1486 kV/cm). In addition, the relationship between the breakdown properties and activation energy of glass ceramics was investigated. In this study, due to the quite high dielectric BDS and comparatively high dielectric constant, the energy densities reach to 2.8 J/cm 3 (treated at 950 °C by microwave heat method), which is relatively high for bulk materials. [ABSTRACT FROM AUTHOR]

The electrospinning method combined with high temperature thermal annealing was used to prepare TiO 2 fibers modified with different concentrations of Co 3 O 4. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), desktop scanning electron microscope (TM3030)-energy spectrometer (SwiftED3000), thermal analyzer (TGA), X-ray diffractometer (XRD), X-ray photoelectron energy Spectral analyzer (XPS), Brunauer–Emmett–Teller (BET) (BET) were used to study the influence of different cobalt oxide concentrations on the morphology of mesoporous TiO 2 fibers. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and continuous cycle method were used to evaluate the fiber's oxygen evolution reaction (OER) and oxygen reduction (ORR) reactivity. It was found that the fiber with a molar ratio of Co to Ti of 1:10 showed the best performance for both OER and ORR reactions in alkaline solution. The fiber showed an overpotential of 382 mV at a current density of 10 mA cm−2, a Tafel slope of 58 mV·dec−1, and a half-wave potential change of only 10 mV after 4000 CV cycles. It has an onset potential of 0.83 V (vs RHE) in the ORR reaction. The OER/ORR overpotential gap (E) of 0.85 V is significantly lower than commercial platinum/carbon and bulk TiO 2 analogs. Obviously, this catalytic activity stems from the synergy between Co 3 O 4 and TiO 2 fibers. In addition, the higher specific surface area and the presence of disordered mesopores provide a higher charge carrier density during the electrocatalytic process, which improves the reaction activity. [Display omitted] • TiO 2 was adopted in present research to replace carbon as a catalyst support substrate. • The Co 3 O 4 @TiO 2 nanofiber possess an unique mesoporous structure, which provides more active sites for the reaction, and makes good catalytic performance for the reaction through the synergistic of TiO 2 and Co 3 O 4. • The Co 3 O 4 @TiO 2 nanofibers show good catalytic performance for both the OERand ORR. [ABSTRACT FROM AUTHOR]

Highlights: [•] Concerted mechanisms of thiocarbonyl ene reactions were verified by DFT calculations. [•] Substituent affects the activation energy and regioselectivity. [•] The charge difference on C1 and S in enophile controls the regioselectivity. [•] There are good linear relationships between the CT and the activation energies. [ABSTRACT FROM AUTHOR]

Abstract: Adsorptions of methane on Pdn clusters were studied using PW91 functional with a plane wave basis set to understand the role of Pdn clusters in detecting trace amounts of CH4 in air and the observations made in the temperature-programmed desorption experiment on the CH4 physisorption on Pd clusters supported by Al2O3. Fifteen Pdn clusters consisting of up to 13 atoms were chosen to form various CH4 Pdn adducts. Dispersion correction to the adsorption energy was also calculated. Our results show that the interaction between CH4 and Pdn cluster depends strongly on the adsorption site and CH4 orientation. The most preferred adsorption occurs (1) along the C ∞ axis of the linear Pdn clusters, (2) perpendicular to the main C n axis of the planar Pdn clusters, and (3) at the atop site of the three-dimensional Pdn clusters. All four coordination modes of σ−bonds, η1, η2–C,H, η2–H,H, and η3, are found in these adducts. Additionally, the η3–C,H,H, η3-Pd,Pd,Pd, and η1-Pd,Pd modes are identified. The η1 σ−bond is found to be dominant in the CH4 Pdn adducts with Pdn clusters larger than trimer. Our results show that the CH4 does not adsorb on top of the monolayer Pd clusters. Furthermore, the adsorption strength is more dependent on the thickness of the Pd clusters than the cluster size. [ABSTRACT FROM AUTHOR]

The isotope effect on integral cross section and product rotational polarization has been investigated for title reactions D+ +H2 and H+ +D2 by quasiclassical trajectory method. The calculated results show the isotope effect on the integral cross section is weak at low collision energy but remarkable at high collision energy. However, the rotational polarization of the product HD molecule is sensitive to the mass factor at low collision energy of 0.524eV. The initial vibrational excitation plays a more important role in the anisotropic distribution of the product angular momentum vector for the reaction D+ +H2 than that for the reaction H+ +D2. [Copyright &y& Elsevier]

Immunosuppressive myeloid-derived suppressor cells (MDSCs) continuously expand and lead to poor outcome during sepsis. The activation of liver X receptor (LXR) can mitigate sepsis-induced liver and myocardial damage. This study aims to determine whether LXR plays a protective role in sepsis by regulating MDSCs. Cecal ligation and puncture(CLP)was used to induce sepsis in mice. The mice were then treated with LXR agonist GW3965 (3 mg/kg) or vehicle 1 h, 6 h, 12 h, 24 h, 48 h, 72 h postoperatively. The effect of LXR on the survival rate and multi-organ injury induced by sepsis was evaluated by survival analysis, histological staining, biochemical analysis and ELISAs. The percentages of MDSCs and T cells were detected using flow cytometry. The mRNA expressions of LXR and ATP-binding cassette transporter A1 (ABCA1) were measured using real-time quantitative PCR (RT-qPCR). ABCA1 protein level was determined using immunofluorescence staining. LXR agonist GW3965 treatment improved the survival of septic mice, accompanied by reduced multi-organ injury and a decreased level of inflammatory cytokines. Furthermore, GW3965 treatment decreased MDSCs abundance in spleen by boosting the apoptosis of spleen MDSCs, therefore ameliorating their immunosuppressive activity. Meanwhile, bacteria clearance in tissues was enhanced after the GW3965 administration in septic mice. Mechanistically, GW3965 activated LXRβ and its downstream target ABCA1 to initiate the apoptosis of spleen MDSCs. These findings provide new insights into the relationship between LXR and MDSCs in sepsis, thus revealing a potentially effective approach to target the immunosuppression of sepsis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The preparation method of fiber catalyst is simple. • The reaction was carried out under mild conditions. • The chosen fiber catalyst PAN T-UdA F-I is highly efficient and recyclable. • Possible mechanism based on the fiber's microenvironment is proposed. Fiber-supported quaternary ammonium catalysts for the fixation of CO 2 with epoxides were designed and prepared via amination and quaternization of polyacrylonitrile fiber, followed by ion exchange with different anions. The impact of different quaternary ammonium structures and counter anions on the reaction yields was investigated. A fiber catalyst (PAN T-UdA F-I) with a C 11 carboxylic acid chain and iodide counter anion exhibited excellent catalytic activity in the fixation of CO 2 with epoxides under mild and solvent-free conditions (80 °C, 0.1 MPa) with a very low catalyst amount (0.5 mol%), and diverse cyclic carbonates were obtained in yields between 24–99 %. PAN T-UdA F-I could be conveniently separated by filtration and showed good recyclability and durability till the 4th cycle. Novel cooperative catalytic mechanism is proposed where the ionic microenvironment plays a crucial role to stabilize the ionic intermediates and lowers the activation energy of the reaction. [ABSTRACT FROM AUTHOR]

Zinc ion, as inevitably incorporated into cement clinker during the waste co-disposal of cement kiln, has conspicuous influence on the phase composition and properties of clinker minerals. The present study employs the state-of-the-art density functional theory calculation to clarify the mechanism of zinc incorporation into clinker crystals at the atomic level. We theoretically predicted the substitution preference of zinc ions in silicate clinker phases, which is in good agreement with previous experimental results. Furthermore, it finds that the zinc substitution preference is mainly governed by the overall crystal deformation and local structural distortion. Herein, two indicators defined as "relative volume changes" and "bonding structure difference" are proposed to characterize and predict zinc-doping mechanism in silicate clinker phases, which performs much better than previous indicators such as "ionic radius" and "structure difference factor". This theoretical method is supposed to be generalized to investigations of other chemical impurities and clinker systems, which facilitates the design and modification of doping-enhanced cementitious materials. Image 1 • The Zn incorporation into complex silicate clinker is studied at atomic scale. • The Zn substitution mechanism in clinker system is fully clarified. • We proposed useful theoretical method to facilitate experimental studies of clinker. [ABSTRACT FROM AUTHOR]