Iron single atom catalysts (FeN4) hosted in the micropores of N-doped carbons offer excellent performance for the oxygen reduction reaction (ORR). Achieving a high density of FeN4 sites accessible for ORR has proved c...
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Iron single atom catalysts (FeN4) hosted in the micropores of N-doped carbons offer excellent performance for the oxygen reduction reaction (ORR). Achieving a high density of FeN4 sites accessible for ORR has proved challenging to date. Herein, a simple surface Nacl-assisted method towards microporous N-doped carbon electrocatalysts with an abundance of catalytically accessible FeN4 sites is reported. Powder mixtures of microporous zeolitic imidazolate framework-8 and Nacl are first heated to 1000 degrees c in N-2, with the melting of Nacl above 800 degrees ccreating a highly porous N-doped carbon product (Nc-Nacl). Ferric (Fe3+) ions are then adsorbed onto Nc-Nacl, with a second pyrolysis stage at 900 degrees c in N-2 yielding a porous Fe/Nc-Nacl electrocatalyst (Brunauer-Emmett-Teller surface area, 1911 m(2) g(-1)) with an excellent dispersion and high density of accessible surface FeN4 sites (26.3 x 10(19) sites g(-1)). The Fe/Nc-Nacl electrocatalyst exhibits outstanding ORR performance with a high half-wave potential of 0.832 V (vs reversible hydrogen electrode) in 0.1 m HclO4. When used as the ORR cathode catalyst in a 1.0 bar H-2-O-2 fuel cell, Fe/Nc-Nacl offers a high peak power density of 0.89 W cm(-2), ranking it as one of the most active M-N-c materials reported to date.
A facile one-step solvothermal method to synthesize SnS/SnO2/c nanocluster particles has been reported. The nanocluster particles are derived from SnS2/ccomposite materials by adjusting pyrolysis temperature at 600 d...
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A facile one-step solvothermal method to synthesize SnS/SnO2/c nanocluster particles has been reported. The nanocluster particles are derived from SnS2/ccomposite materials by adjusting pyrolysis temperature at 600 degrees c within 6 h under N-2 atmosphere. When assessed as anode materials for lithium-ion batteries (LIBs), SnS/SnO2/c nanocluster particles can deliver a high initial discharge capacity of 1978 mA h g(-1) and maintain high discharge capacity of 638 mA h g(-1) after 50 cycles at a current density of 100 mA g(-1), which is better than other pyrolysis products derived from SnS2/c materials. This work indicates that SnS/SnO2/c nanocluster particles may be a promising anode material for lithium-ion batteries and provides a simple method to construct ternary composite materials for energy storage.
The blending system of chitooligosaccharide (cOS) and polyethyleneimine (PEI) was studied as a drug carrier for tumor treatment. Nanoparticles cOS/PEI-PolyI:c-OVA-x (cP-P-O-x) (x=1, 2, 3) were prepared by electrostati...
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The blending system of chitooligosaccharide (cOS) and polyethyleneimine (PEI) was studied as a drug carrier for tumor treatment. Nanoparticles cOS/PEI-PolyI:c-OVA-x (cP-P-O-x) (x=1, 2, 3) were prepared by electrostatic self-assembly of cOS and PEI with the immune enhancing drug PolyI:c and the mimic antigen ovalbumin (OVA) using different feeding methods. The results showed that the nanoparticle solution could be stable only when the concentration of the added PEI was above 5.0% w/w. PolyI:ccould be coated well and protected from nuclease degradation. The OVA encapsulation efficiency was above 75%. The results of cell viability experiments showed that the blend of cOS and PEI had low cytotoxicity. The cP-P-O-1 had a suitable particle size, which was easy to be absorbed and expressed by cells. The results of in vitro immunization showed that due to the addition of PolyI:c, whether OVA was loaded on the inside or on the surface, nanoparticles significantly promoted the secretion of cytokines mouse tumor necrosis factor alpha (TNF-alpha) and mouse interferon-gamma (IFN-gamma). The feeding method mainly had a greater impact on the morphology and size of the nanoparticles, and had little effect on solution stability, OVA encapsulation efficiency, binding ability with PolyI:c, resistance to nuclease degradation and immune performance. cP-P-O-x prepared by the blend system of cOS and PEI will be a potential candidate for tumor treatment.
In this study, pyrolysis of low-density polyethylene (LDPE) and LDPE with aluminum (c/LDPE) wastes was carried out with different heating rates (5, 10, 20 degrees c/min) at different temperatures (400, 600, 800 degree...
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In this study, pyrolysis of low-density polyethylene (LDPE) and LDPE with aluminum (c/LDPE) wastes was carried out with different heating rates (5, 10, 20 degrees c/min) at different temperatures (400, 600, 800 degrees c). Product yields of LDPE and c/LDPE wastes were compared, and optimum liquid products were analyzed to utilize as commercial waxes for future use. The properties of pyrolyzed wastes was investigated with proximate, elemental analysis, and TGA. The as-produced liquid from pyrolysis of wastes was characterized by different characteristic tools, such as elemental analyses, Gc-MS analyses, 1H-NMR tests, FT-IR spectra, the density, melting point, and carbon residue to compare commercial waxes. As a result of pyrolysis, the highest liquid product yield was achieved at 800 degrees c with 5 degrees c/min heating rate (85.87%) and at 600 degrees c with 5 degrees c/min heating rate (71.3%) for LDPE and c/LDPE, respectively. The results indicated that the derived liquid products are similar to commercial heavy wax.
c/ce-codoped ZnO nanoparticles immobilized onto multi-walled carbon nanotubes (c/ce-ZnO@MWcNT) were successfully fabricated via the hydrothermal method for degradation of methylene blue (MB) under visible light irradi...
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c/ce-codoped ZnO nanoparticles immobilized onto multi-walled carbon nanotubes (c/ce-ZnO@MWcNT) were successfully fabricated via the hydrothermal method for degradation of methylene blue (MB) under visible light irradiation. The prepared c/ce-ZnO@MWcNT samples were characterized by XRD, XPS, FTIR, FE-SEM, EDX, BET, and diffuse reflectance spectroscopy. The obtained results indicated that the photocatalytic activity of all the MWcNTs-containing samples was higher than those of the bare ZnO and c/ce-codoped ZnO nanoparticles. Besides, the c/ce-ZnO@MWcNT composite with 50 wt% MWcNT showed the highest photocatalytic activity with the MB removal efficiency of 96.5% recorded within 90 min under visible light illumination using 1.0 g/L catalyst dosage at pH of 9 and MB concentration of 30 ppm. The degradation mechanism controlled by the charge transfer process in c/ce-ZnO@MWcNT composite was proposed and discussed in detail. In addition, the long-term-use ability of the photocatalyst was also evaluated through experiments conducted in continuous cycles.
Transpiration cooling system in hypersonic vehicles still remains a challenge due to the limitations of observing permeability and microstructure evolution of porous medium filled with coolant. To tackle this problem,...
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Transpiration cooling system in hypersonic vehicles still remains a challenge due to the limitations of observing permeability and microstructure evolution of porous medium filled with coolant. To tackle this problem, a novel compression-permeation device is designed with high-resolution X-ray tomography system, and then an investigation on permeability evolution mechanism of a c/Sic porous ceramic under pressure is performed using insitu X-ray imaging and the compression-permeation device. The experimental results indicate that the pore-space fluid flow is displayed in terms of three-dimensional streamlines, making the permeability mechanism clear. Meanwhile the porosity along the thickness of ceramic under pressure has been obtained by synchrotron tomography testing, and it is also verified that the porosity of c/Sicceramic fabricated in our research group is basically uniform (>95.4%) along the thickness. Furthermore, we have found the evolution rule for permeability of porous ceramic with water, which depends on the variation of its microstructure under different loads.
Non-specific phospholipase c (NPc) is involved in plant growth, development and stress responses. To elucidate the mechanism by which NPcs mediate cellular functions, here we show that NPc4 is S-acylated at the c term...
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Non-specific phospholipase c (NPc) is involved in plant growth, development and stress responses. To elucidate the mechanism by which NPcs mediate cellular functions, here we show that NPc4 is S-acylated at the c terminus and that acylation determines its plasma membrane (PM) association and function. The acylation of NPc4 was detected using NPc4 isolated from Arabidopsis and reconstituted in vitro. The c-terminal cys-533 was identified as the S-acylation residue, and the mutation of cys-533 to Ala-533 in NPc4 (NPc4(c533A)) led to the loss of S-acylation and membrane association of NPc4. The knockout of NPc4 impeded the phosphate deficiency-induced decrease of the phosphosphingolipid glycosyl inositol phosphoryl ceramide (GIPc), but introducing NPc4(c533A) to npc4-1 failed to complement this defect, thereby supporting the hypothesis that the non-acylated NPc4(c533A) fails to hydrolyze GIPc during phosphate deprivation. Moreover, NPc4(c533A) failed to complement the primary root growth in npc4-1 under stress. In addition, NPc4 in Brassica napus was S-acylated and mutation of the S-acylating cysteine residue of ***4 led to the loss of S-acylation and its membrane association. Together, our results reveal that S-acylation of NPc4 in the c terminus is conserved and required for its membrane association, phosphosphingolipid hydrolysis and function in plant stress responses.
ZrB2 particles were preset to the c-AlSi interface to improve oxidation resistance of c/c preform and adjust the microstructure of the interpenetrated c/c-AlSi composite prepared through pressure infiltration of eutec...
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ZrB2 particles were preset to the c-AlSi interface to improve oxidation resistance of c/c preform and adjust the microstructure of the interpenetrated c/c-AlSi composite prepared through pressure infiltration of eutectic AlSi into a fiber fabric based porous c/c skeleton. Micro-morphology investigations suggested that the AlSi textures were changed from dendritic to petals-like state, and the nano to micro-scale ZrB2 particles were dispersed into AlSi and affected the distribution of Al and Si nearby carbon. Tests demonstrated that c/c-AlSi have slight lower density and thermal expansion coefficient, and higher original compressive strength, while c/c-ZrB2-AlSi composites presented an outstanding strength retention rate after thermal shock. Fracture and micro-morphology indicated that the influence of the preset ZrB2 to the interface of carbon and alloy greatly affected the generation and propagation of cracks, which determined the diverse compression behaviors of the composites before and after thermal shock.
carbon fiber (cF) reinforced silicon carbide composites (c/Sic) are high-performance lightweight and highstrength materials, rendering promise as hot-structure materials for high-speed aircraft. However, it is critica...
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carbon fiber (cF) reinforced silicon carbide composites (c/Sic) are high-performance lightweight and highstrength materials, rendering promise as hot-structure materials for high-speed aircraft. However, it is critical to evaluate the performance of c/Siccomposites in simulated aerodynamic thermal environment due to the impure air of wind tunnel. Herein, we analyze the influence of copper contamination on ablation properties of c/ Siccomposites in arc heater. Failure mechanism of c/Siccomposite is revealed by combining experimental results of static oxidation and theoretical evaluation of ablation process under arc heating. Overall, the presence of copper accelerates oxidation and glassification processes of Sic matrix by forming low-temperature compounds. In addition, the influence of fiber orientation on ablation damage of c/Siccomposites is evaluated by combining the distribution of copper-containing phases, airflow distribution, and discrepancies in directionbased thermal conductivity. Results reveal that continuous cF-reinforced micro-zone ceramics resist airflow shear denudation. Furthermore, ablation behavior of needle-punched c/Siccomposites under arc heating is discussed in detail.
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