In this study, high quality Magnéli phase Ti4O7 bulks with electrical conductivity up to 961.5 S cm−1 were successfully prepared by spark plasma sintering (SPS) and then served as electrode materials ...for electrochemical oxidation of azo dye methyl orange (MO). The influences of current density and initial dye concentration on the removal rates of MO and chemical oxygen demand (COD) were studied. Removal of MO and COD exhibited an increase with increasing current density and decreasing initial concentration of MO. Complete removal of MO was realized within a short time under all experimental conditions. The removal rate of COD reached 91.7% when current density was 10 mA cm−2 and initial dye concentration was 100 mg L−1. In addition, the electrochemical oxidation rate could be described through a pseudo-first-order kinetic constant k, and the obtained experimental results could be well fitted with a proposed kinetic model in all the examined conditions. Possible degradation mechanisms for electrochemical oxidation of MO by Ti4O7 electrode were proposed on the basis of intermediate products analysis. Tests were also conducted with other commercial electrodes for comparison, including commercial graphite, stainless-steel and dimension stable anode (DSA) electrodes. The results showed that Ti4O7 anode exhibited the fastest electrochemical oxidation rates than those of the other electrodes. This study provides a feasible method for realizing high efficiency of electrochemical oxidation degradation by Ti4O7 electrode.
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•High accuracy kinetic model between electrolysis time and operating parameters was established.•The possible mechanism of methyl orange degradation by Ti4O7 electrode was proposed.•Ti4O7 electrode shows the fastest removal rate of methyl orange in the comparative experiments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Ternary eutectic mixture of myristic–palmitic–stearic acid (MA–PA–SA) was prepared.•MA–PA–SA/EG (expanded graphite) composite PCM was prepared by pore structures of EG.•Optimum absorption ratio of ...MA–PA–SA in EG was obtained as 13:1 (by mass).•The prepared MA–PA–SA/EG had a good thermal performance and reliability.
Based on theoretical calculation, myristic acid–palmitic acid–stearic acid ternary eutectic mixture (MA–PA–SA) with a mass ratio of MA:PA:SA=52.2:29.4:18.4 was prepared firstly. Then, the MA–PA–SA/expanded graphite (EG) composite phase change material (PCM) with an optimum mass ratio of MA–PA–SA: EG=13:1 was fabricated. The prepared MA–PA–SA and MA–AP–SA composite PCM are characterized by the scanning electron microscope (SEM), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetry analyzer (TG). The SEM and FT-IR results showed that the MA–PA–SA was uniformly adsorbed into the network porous structure of EG. The DSC results indicated that the melting and freezing temperatures and latent heats of MA–PA–SA/EG composite PCM were 41.64°C and 42.99°C, and 153.5J/g and 151.4J/g respectively. TG analysis test revealed that the prepared MA–PA–SA/EG composite PCM has a high thermal stability in working temperature range. Thermal cycling test result showed the melting and freezing temperatures and latent heats of the prepared composite PCM changed by 0.28°C and 0.48°C, and −1.63% and −1.32% respectively after 1000 thermal cycles. The thermal conductivity of MA–PA–SA/EG composite PCM was improved by the high thermal conductivity of the EG. All results indicated that the prepared MA–PA–SA/EG composite PCM has proper phase change temperature, high latent heat and thermal conductivity, and good thermal reliability and stability for thermal energy storage in solar heating, waste heating recovery systems and other potential applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•PA–SA/CNTs composite PCMs with different contents of CNTs (5–8wt.%) were prepared.•Thermal conductivities of PA–SA/CNTs were significantly improved due to the CNTs.•Thermal release rates of ...PA–SA/CNTs were much higher than that of PA–SA.•The prepared PA–SA/CNTs composite PCMs had a good thermal reliability.
The effect of carbon nanotubes (CNTs) on thermal behavior of palmitic–stearic acid binary eutectic mixture (PA–SA) was investigated experimentally. Four samples of PA–SA/CNTs composite phase change materials (PCMs) with mass fractions of CNTs of 5–8wt.% at an increase of 1wt.% were prepared. The thermal properties of the PA–SA/CNTs composite PCMs characterized by Differential Scanning Calorimeter indicated that the phase change temperatures and latent heats of the composites changed slightly as the change of the mass fraction of CNTs. The thermal conductivities of the PA–SA/CNTs composite PCMs increased by 20.2%, 26.2%, 26.2% and 29.7% respectively when the mass fractions of CNTs were 5wt.%, 6wt.%, 7wt.% and 8wt.%. The thermal performance test results showed that the thermal release rate of the prepared composite PCMs increased due to the addition of CNTs while the storage rate decreased. Thermal cycling test results revealed that the PA–SA/CNTs composite PCMs performed well in thermal reliability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•The ternary eutectic mixture of lauric–myristic–palmitic acid (LA–MA–PA) was prepared.•The form-stable composites PCM of LA–MA–PA/EG (expanded graphite) were fabricated.•The maximum absorption of ...LA–MA–PA in the LA–MA–PA/EG is 94.7wt%.•The thermal conductivity of LA–MA–PA/EG is 1.67W/mK, a sharp increase than that of LA–MA–PA.
Based on the theoretically calculated mass ratio and the melting temperature of ternary eutectic mixtures, the ternary eutectic mixture of lauric acid (LA), myristic acid (MA) and palmitic acid (PA) was prepared firstly. The differential scanning calorimetry (DSC) results indicated that the eutectic mixture was composed by LA, MA and PA in the ratio of 55.24:29.74:15.02 (by mass). Then the LA–MA–PA was absorbed in expanded graphite (EG), which acts as a supporting material, to prepare six kinds of composite phase change material (PCM). The optimal mass ratio of LA–MA–PA to EG is found. The SEM, FT-IR and DSC comprehensive characterization results show that EG interacted with the capillary tubes and surface tension of LA–MA–PA via its porous structure, instead of any chemical action. At the maximum mass ratio of LA–MA–PA to EG of 18:1 (by mass), the phase change temperature and latent heat of LA–MA–PA ternary eutectic mixture were 31.41°C and 145.8J/g respectively; and the LA–MA–PA/EG composite PCM had a phase change temperature of 30.94°C and a latent heat of 135.9J/g, and the thermal conductivity of the LA–MA–PA/EG was measured as 1.67W/mK, a sharp increase than that of LA–MA–PA. Thermal cycling test showed that the LA–MA–PA/EG composite had a good thermal reliability. Based on all results, it was concluded the prepared LA–MA–PA/EG composite PCM has a proper melting temperature and latent heat for low temperature thermal storage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•A highly sensitive gas sensor based on WO3–Au nanofibers has been fabricated.•WO3–Au composite nanofibers were obtained by electrospinning with subsequent annealing.•WO3–Au composite shows higher ...sensing performance than pure WO3.•Gold content can be easily tuned to optimize the sensing performance.
A highly sensitive and selective gas-sensing material based on gold (Au)-functionalized tungsten oxide (WO3) composite nanofibers (NFs) has been fabricated under mild conditions by electrospinning (ES). Au nanoparticles (NPs)-decorated WO3 composite NFs were obtained by ES of the tungsten precursor (ammonium metatungstate hydrate) (AMT) and polyvinyl alcohol (PVA) solution followed by a two-step annealing treatment. The chemical and structural characterizations of the resulting composite nanofibers have been performed with various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and inductively coupled plasma optical emission spectrometry (ICP-OES). The gas-sensing properties of the WO3–Au composite NFs with different Au contents (0.01M and 0.1M) toward volatile organic compounds (VOCs) (such as n-butanol) have been studied. A discussion concerning the role of Au content and the operating temperature is given to optimize the sensitivity, the dynamic response–recovery behaviors and consequently the efficiency of the WO3–Au composite sensor.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
(Ti,M)(C,N)-Based Cermets were synthesized from (Ti,M)(C,N)-Ni-Co composite powders by vacuum sintering. The material phase evolution, microstructure and densification behavior were investigated ...under different sintering temperature from 800 °C to 1400 °C. Results showed that deoxidation occurred and solid phase diffusion observed below 1200 °C. The solid phase liquidization appeared from 1200 °C to 1350 °C, resulting in decrease of pores in the material. Above 1350 °C, the liquid phase fully melted to fill the pores of material, and the cermets approach densification lead to the maximum value of its transverse rupture strength and hardness. (Ti,M)(C,N)-based cermets prepared by vacuum sintering have a hard phase of “weak core/rim structure".
•(Ti,M)(C,N)-based cermet with"weak core/rim structure"was prepared by vacuum sintering.•Both the core and rim phase were (Ti,M)(C,N) solid solution with similar composition.•Cermet reached densification by vacuum sintering.•Low-pressure sintering could improve the mechanical properties of cermet.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Selective entrapment of precious metals from industrial wastes containing various metals is a most challenging branch of environmental science. Developed methods like solvent or solid-phase ...extraction, ion exchange, co-precipitation, membrane filtration, and adsorption rely on chelation, electrostatic attraction, or ion exchange, and these methods present limited selectivity and require post-treatment for further application. Herein, an original concept is reported involving the utilization of the superior catalytic properties of Pd selectively for efficient entrapment of Pd from other metals. Specifically, side chains of poly(vinyl alcohol) (PVA) functionalized with alkynyl groups are catalytically dimerized using Pd(II), which forms gels. The Pd(II) ions are coordinatively encapsulated into the gel networks, while the other metal ions are excluded from the networks, thus allowing the separation and immobilization of Pd. The entrapped Pd(II) is also reduced to Pd(0) nanoparticles (PdNPs) forming PdNPs@alkyne-PVA aerogels that exhibit a high catalytic activity for the Suzuki–Miyaura cross-coupling reaction. PdNPs@alkyne-PVA aerogels are further carbonized to PdNPs@C networks for the efficient electrochemical hydrogen evolution reaction. This method provides an effective way not only to selectively separate Pd but also to utilize the entrapped Pd resources for multiple catalyses without further post-treatment of the entrapped Pd source.
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A series of novel matrine–1H-1,2,3-triazole–chalcone conjugates was synthesized and their anticancer activity against A549, Bel-7402, Hela, and MCF-7 cancer cells was evaluated. Most ...of the conjugates displayed higher potency than their components. Compounds 6h and 6i exhibited more potent anticancer activity than 5-fluorouracil against the four tested human cancer cell lines and lower cytotoxicity to NIH3T3 normal cells. Flow cytometry tests demonstrated that compound 6h could induce apoptosis of A549 cells in a concentration-dependent manner. Moreover, 6h could efficiently suppress human tumor growth in mouse xenograft model without causing obvious toxicities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This study aimed to investigate the performance of a novel encapsulated phase change material (PCM) photovoltaic/thermal (PV/T) system. A PCM, which has a high latent heat capacity, can absorb energy ...from a PV cell and reduce the operating temperature, improving both the electrical and thermal efficiencies of the panel. In this study, a computer model based on a PCM PV/T panel is developed, and its accuracy is verified using experimental data. The effect of the phase change temperature on the performance of the panel was analyzed by numerical simulation. When the phase change temperature was 30.1 °C, the system exhibited a maximum electrical efficiency of 8.2% and a thermal efficiency of 71.8%. When the phase change temperature was 20.24 °C, the system had a maximum exergy efficiency of 33.7%. In general, the temperature of the PCM integrated into the PV/T system should not be too high.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
For an aperture synthesis radiometer (ASR), the visibility and the modified brightness temperature (BT) are related to the Fourier transform when the distance between the system and the source is in ...the far-field region. BT reconstruction can be achieved using G-matrix imaging. However, for ASRs with large array sizes, the far-field condition is not satisfied when performing performance tests in an anechoic chamber due to size limitations. Using far-field imaging methods in near-field conditions can introduce errors in the images and fail to correctly reconstruct the BT. Most of the existing methods deal with visibilities, converting near-field visibilities to far-field visibilities, which are suitable for point sources but not good for extended source correction. In this paper, two near-field imaging methods are proposed based on the near-field distance. These methods enable BT reconstruction in near-field conditions by generating improved resolving matrices: the near-field G-matrix and the F-matrix. These methods do not change the visibility measurements and can effectively image both the point source and the extended source in the near field. Simulations of point sources and extended sources in near-field conditions demonstrate the effectiveness of both methods, with F-matrix imaging outperforming near-field G-matrix imaging. The feasibility of both near-field imaging methods is further validated by carrying out experiments on a 10-element Y-array system.
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