The aim of the present study was to evaluate the antifungal activity of seaweed champia parvula and identification of active compounds for this action. In this regard, c. parvula crude extracts were obtained from n-he...
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The aim of the present study was to evaluate the antifungal activity of seaweed champia parvula and identification of active compounds for this action. In this regard, c. parvula crude extracts were obtained from n-hexane, ethyl acetate, chloroform, methanol, and water used to study the antifungal action. Results showed that methanolic extract had potent action against c. albicans, c. tropicalis, T. mentagrophytes, and ***, with the highest inhibition of 16.7 mm found against c. tropicalis. Minimum inhibition concentration at 12.5 and minimum fungal concentration at 25 mu g/mL were found in the methanolic extract. Therefore, to identify the bioactive compound for this antifungal action in the methanolic extract, thin-layer chromatography (TLc) and reverse-phase high-performance liquid chromatography (RP-HPLc) were used. The RP-HPLc had three peaks with retention times at 3.30, 3.86, and 4.73 min, showing the presence of ester fatty acid compound. Further, these compounds were characterized by nuclear magnetic resonance (NMR), gas chromatography (Gc), and liquid chromatography-mass spectrometry (Lc-MS), which showed the presence of long-chain aliphatic fatty acid like eicosanoic acid with formation of oct-1-en-3-ol compounds attached.
B4c modified HfB2-Siccoating for c/c substrate was designed to expand the application of HfB2-Sic based coating in low-medium temperature environment. The oxidation protection behavior of HfB2-Sic based ceramiccoati...
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B4c modified HfB2-Siccoating for c/c substrate was designed to expand the application of HfB2-Sic based coating in low-medium temperature environment. The oxidation protection behavior of HfB2-Sic based ceramiccoatings with and without B4c at 1073, 1273 and 1473 K was tested and analyzed. The experimental results reveal that the oxidative damage of HfB2-Siccoated c/c reduces by over 20% after introducing B4c, which may be due to the protection of borosilicate glass with more suitable viscosity during oxidation. Meanwhile, B4ccan improve the oxidation protection ability of HfB2-Siccoating best at 1473 K. And the introduction of B4ccan reduce the mass loss of HfB2-Siccoated c/c sample by 77.6% after oxidation for 58 h at 1473 K. The fluidity of glass film becoming better with temperature-rising, and the fluid borosilicate glass layer makes the coated samples have the best anti-oxidation properties at 1473 K among these three temperatures.
Every day, a large amount of food waste (FW) is generated that causes serious environmental problems such as the production of greenhouse gases and leachate. A possible treatment for this waste is anaerobic digestion ...
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Every day, a large amount of food waste (FW) is generated that causes serious environmental problems such as the production of greenhouse gases and leachate. A possible treatment for this waste is anaerobic digestion (AD), but there are several problems associated with the accumulation of volatile fatty acids (VFA), foaming, or low buffer capacity. In order to resolve or mitigate this problem, FW was mixed with cabbage and cauliflower (ccF) leaves and stalks at different carbon/nitrogen ratios (c/N) to add value to this agricultural waste and benefit from the advantages of co-digestion. Under the study conditions, promising results were obtained during the co-digestion of FW and agricultural wastes at c/N = 45. These include a high biodegradability (98%), a methane yield of 475 mL(STP) cH4/g VS, and an organic loading rate (OLR) of 0.06 kg of VS/m(3) h for the ccF and FW mixture (ccF + FW). Anaerobicco-digestion of ccF + FW might be an interesting option for the simultaneous treatment of these types of organic waste, with the consequent social and environmental benefits.
A new strategy of recycling and reusing abandoned carbon fiber reinforced plastics (cFRP) is proposed: cFRPs are first fully carbonized to cF reinforced carbon (c/c) preforms, and then are manufactured into high value...
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A new strategy of recycling and reusing abandoned carbon fiber reinforced plastics (cFRP) is proposed: cFRPs are first fully carbonized to cF reinforced carbon (c/c) preforms, and then are manufactured into high value-added c/ccomposites. The results showed that the carbon residue rate of epoxy-resin (EP) matrix was fully recovered as the decomposition route of EP matrix was changed by charring agent. The recycled cF (rcF) was not markedly oxidized or thermally damaged, and possessed comparable properties with those of the virgin cF (vcF) after pyrolysis. The pyrolyticchar had no obvious negative effect on the densification efficiency of the rcF reinforced carbon (rcF/c) composites. Both of the rcF/c and vcF reinforced carbon (vcF/c) composite bodies were quite dense, and exhibited almost no difference in their microstructures. The rcF/c and vcF/ccomposites therefore had quite close interface bonding strength (12.6 MPa and 13.0 MPa, respectively), and bending strength (106.4 MPa and 111.5 MPa, respectively). Furthermore, the rcF/ccomposites possessed comparable ablative rate with that of the vcF/ccomposites. The rcF/ccomposites derived from abandoned cF/EP composites present a great potential to be used as substitutes for vcF/ccomposites owing to their indistinguishable properties.
At present, the high theoretical specificcapacity cuO-based anodes are considered as a potential host for lithium-ion batteries (LIBs). Unfortunately, the intrinsic poor conductivity of metal oxide and the huge volum...
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At present, the high theoretical specificcapacity cuO-based anodes are considered as a potential host for lithium-ion batteries (LIBs). Unfortunately, the intrinsic poor conductivity of metal oxide and the huge volume expansion during the cycling caused serve capacity fading and unsatisfactory cycling stability. Here, a porous free-standing octagonal flower-like copper oxide (cuO)/carbon(c)/nickel foam (NF) multilevel structure is synthesized. The design of carbon-coated ensures excellent mechanical strength, chemical stability and conductivity of nanocomposite, which effectively prevent the collapse and corrosion of the active material during cycle. In addition, 3D interconnected structure shortened the transmission distance of electrons and Li+, improving the ability of fast charge and discharge. The cuO/c/NF electrode exhibits high performance in cycling as the anode material for LIBs. The initial charge/discharge specificcapacity of the octagonal flower-like cuO/c/NF electrode is 871.1 mA h g(-1)and 916.06 mA h g(-1)at 0.5 A g(-1), respectively. It achieves an outstanding discharge specificcapacity of 505 mA h g(-1)at 2 A g(-1)after 800 cycles. This work combines cuO with a conductive matrix (carbon) and a 3D porous NF, effectively enhancing the electrochemical properties of cuO, which is of certain significance to the further research.
The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronicconductivity of Na3V2(PO4)(3). Based on this, Na3V2(PO4)(3)/ccomposites with diverse ratios of citric a...
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The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronicconductivity of Na3V2(PO4)(3). Based on this, Na3V2(PO4)(3)/ccomposites with diverse ratios of citric acid are synthetized via rheological phase reaction way in this work. The consequences display that the Na3V2(PO4)(3)/c-1.5 composite brings a higher initial discharge capacity of 113.2 mAh g(-1) at a current rate of 1 c with coulombic efficiency above 99% during all cycles. The discharge capacity retains at 117.6 mAh g(-1) at the 100th cycle. Even at the high current densities of 5 c and 10 c, the composite also shows superior cycling performance with negligible capacity fading. Its discharge capacities decline from 97 to 92.6 mAh g(-1) at 5 c and from 85.3 to 83.7 mAh g(-1) at 10 c. These remarkable outcomes arise from its preferable morphology with suitable carbon coating because both excess and skimpy carbon seriously affect the microstructure and electrochemical properties of Na3V2(PO4)(3)/ccomposites.
Ba0.25Sr0.75Al2Si2O8 (BSAS), Yb2SiO5 and Y2SiO5 are widely deposited as the main phase of composite coatings or as the functional layer in multilayer coatings. The investigation of monolayer coating can not only broad...
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Ba0.25Sr0.75Al2Si2O8 (BSAS), Yb2SiO5 and Y2SiO5 are widely deposited as the main phase of composite coatings or as the functional layer in multilayer coatings. The investigation of monolayer coating can not only broaden the application of monolayer anti-oxidation coating, but also be an important basis for the design of multilayer and composite coatings. Monolayer BSAS, Yb2SiO5 and Y2SiO5 coatings were deposited on c/Siccomposite by atmospheric plasma spraying (APS). Thermal physics and chemical properties, microstructure, bond stability and oxidation protection of the monolayer coatings were investigated. The results showed that the monolayer coating effectively improved the oxidation resistance of c/Siccomposite. The microstructure and mechanical properties of the coatings play an important role in the bond stability and oxidation resistance of the coated sample. Among the tested coatings, the Y2SiO5 coating exhibited excellent mechanical properties and compact structure, which resulted in the highest bond stability and the best protection.
In order to make carbon/carbon composites suitable for application in gas turbine engine, it is necessary to develop environmental barrier coatings (EBcs) to protect them from reacting with water vapor. In our previou...
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In order to make carbon/carbon composites suitable for application in gas turbine engine, it is necessary to develop environmental barrier coatings (EBcs) to protect them from reacting with water vapor. In our previous work, a novel high-entropy rare-earth disilicate (Lu0.2Yb0.2Er0.2Tm0.2Sc0.2)2Si2O7 ((5RE0.2)2Si2O7) has been developed and verified as a promising candidate for EBcs. In this work, the (5RE0.2)2Si2O7 coating was syn-thesized on the surface of Siccoated c/ccomposites by supersonic atmospheric plasma spraying method. The protective performance and mechanism of this coating under high temperature water vapor environment was explored in detail. Results showed that the weight change of the sample coated with (5RE0.2)2Si2O7 was only 0.2% after corrosion for 100 h at 1500 oc, which proved that (5RE0.2)2Si2O7 coating could significantly improve the resistance of c/ccomposites against water vapor corrosion. This work may provide theoretical basis for the design and application of high-entropy rare-earth silicates as EBcs.
Adopting orthogonal experiments, relevant machinability in wire cut electrical discharge machining (WEDM) of 2D c/Siccomposite was studied. The effects of electrical machining parameters (namely pulse width, pulse in...
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Adopting orthogonal experiments, relevant machinability in wire cut electrical discharge machining (WEDM) of 2D c/Siccomposite was studied. The effects of electrical machining parameters (namely pulse width, pulse interval, and the number of tubes) on machining speed and surface roughness were analyzed. In addition, the effect of fiber orientations on the machinability was also studied. The main effect and interaction of the selected electrical machining parameters were also discussed. The key results show that the fiber orientation effect on machining speed plays a weaker role in WEDM of this composite. For machining speed, the number of tubes and the pulse interval have no interaction in both of machining directions A and B. For surface roughness, the number of tubes and the pulse interval have obvious interaction in both of machining directions A and B. The fiber orientation has a larger effect on the surface roughness than that on machining speed in WEDM of this composite. After analyzing the material removal mechanism, some new significant results show that the carbon fibers are removed in the form of transverse and longitudinal fracture. Interfacial debonding between fiber carbon and Sic matrix, pit, and recast layer form on the machined surface. Micro cracks are observed in the carbon fiber, and a part of the micro cracks are cross.
Hexagonal boron nitride (h-BN) has excellent oxidation resistance, self-healing function, and self-lubricating properties, which can significantly improve the oxidation resistance of c/c-Siccomposites in low or mediu...
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Hexagonal boron nitride (h-BN) has excellent oxidation resistance, self-healing function, and self-lubricating properties, which can significantly improve the oxidation resistance of c/c-Siccomposites in low or medium temperature condition and affect their tribological properties and mechanisms. In this work, c/c-Sic and c/c-BN-Siccomposites were prepared by the same molding, carbonization and liquid silicon infiltration (LSI) processes and the influences of h-BN addition on their microstructure, tribological properties, and mechanisms were investigated. h-BN addition can promote the formation of friction film and reduce the oxidation wear of the composites. compared with c/c-Siccomposites, due to more lubricant components and different matrix structure, the c/c-BN-Siccomposite shows lower wear rate (reduced by 53%) and moderate rather than too high coefficient of friction (coF) and its coF is less influenced by braking velocity. Moreover, the friction process is more stable and does not appear clamping stagnation phenomenon in high braking speed condition.
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