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•The techno-economic feasibility of CO2 hydrogenation into long-chain HCs is compared to other synthesis paths.•Review of performances of Fe and Co catalysts, pointing up K-Fe ...catalysts efficiency for production of long-chain HCs.•Complexity of HCs synthesis from CO2 hydrogenation is reported and need for further studies on reaction mechanism is shown.
In the framework of limiting the concentration of CO2 in the atmosphere, the utilization of CO2 as a feedstock for the synthesis of different products, such as methanol, dimethyl ether and liquid fuels, is gaining a lot of interest. In particular, the Power-to-Liquid (PtL) concept which combines the CO2 hydrogenation with the production of hydrogen from water electrolysis, powered by renewable sources, seems a very interesting solution for the production of liquid fuels and chemicals. It also represents a storage solution for the intermittent renewable energies. In this work, the techno-economic feasibility of the CO2 hydrogenation into long-chain hydrocarbons, compared to the synthesis of other liquid or gaseous products (methanol, DME, hydrogen, methane…) is studied, as well as that of PtL compared to other renewable fuels production pathways. Even if the PtL process is not economically competitive on the market yet, some economic considerations predict a decrease in the production cost of PtL fuels, thus it is worth to study the synthesis of liquid fuels from CO2 and H2 for its several advantages in terms of efficiency and sustainability of the process, especially for middle or long term prospects and for their potential applications as fuel for the heavy-duty, marine and aviation transport, but also as feedstock for the chemical industry. The review is then focused on the hydrogenation of CO2 into liquid fuels. A review of the performances of Fe and Co catalysts is also given, pointing up that iron catalysts are more suitable for the production of long-chain hydrocarbons, especially when potassium-promoted. A state-of-the-art about the kinetic modeling of the reaction and the current industrial demonstrators has also been reported. However, very few data are available and further investigation in this field should be done. This work, summarizing general information about the hydrocarbon synthesis from CO2 hydrogenation, shows the complexity of such a process and points out that further studies about the reaction mechanism, kinetics and the development of a highly active catalyst selective towards long-chain hydrocarbons are needed. This will help to increase the techno-economic feasibility of this challenging process.
Three different deep eutectic solvent (DES)-based extraction procedures were rationally designed and optimized for the recovery of antioxidants from chestnut wood fiber (CWF), a clean and largely ...available solid waste of the tannin industry. First, a mild protocol was developed using a choline chloride (ChCl)/tartaric acid DES at 50 °C, for 90 min. Ellagic acid (EA) was identified as the only low molecular weight phenolic component of the extract. In other experiments, harsher conditions were explored involving treatment of CWF with ChCl-based DESs at 120 °C for 8 h, which afforded a solid sample characterized by high phenolic content (up to 1.0 mg of gallic acid equivalents/mg of sample) and antioxidant properties (EC50 <0.025 mg/mL in the 2,2-diphenyl-1-picrylhydrazyl assay), and containing guaiacyl-syringyl lignin along with EA. Based on these results, a sequential two-step DES-based treatment of CWF was eventually designed, allowing to selectively obtain both an EA-enriched and an EA-free, lignin-enriched sample, with an overall 50% w/w of the starting CWF dissolved. In particular, a 2.3% w/w yield of EA was achieved, which is significantly higher than those reported in the case of DES-based processing of other agricultural wastes. The proposed tunable, straightforward, and eco-friendly approach may allow to fully exploit CWF as a green, cheap, and easily accessible source of high-value products.
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•Chestnut wood fiber (CWF) can be exploited as a clean source of antioxidants.•Selective deep eutectic solvent (DES)-based extraction protocols were developed.•Choline chloride (ChCl)-tartaric acid DES afforded high yields of ellagic acid.•Subsequent treatment of CWF with ChCl-lactic acid DES led to a lignin-rich extract.•All the extracts exhibited a high phenol content and potent antioxidant properties.
Advanced thermal barrier coatings (TBCs) developed by incorporating multicomponent rare earth oxide dopants into zirconia are promising alternative to replace yttria-stabilized zirconia (YSZ) thermal ...barrier coatings. In this study, a zirconia-based nanopowder coating doped by multiple rare earth oxides (YLaYbZr: 5.86 Mol.%Y
2
O
3
-1.99 Mol.%La
2
O
3
-1.98 Mol.%Yb
2
O
3
-ZrO
2
) was synthesized using co-precipitation technique which is advantageous in terms of simplicity and cost-effectiveness. The product was then characterized using X-ray diffraction (XRD) method and field emission scanning electron microscopy (FESEM). The stability of YLaYbZr compound was studied after a heat treating the product at 1300°C for 50 h. The results indicated that the initially obtained powder was a metastable tetragonal (t-prime) zirconia. Rietveld refinement of the XRD data from YLaYbZr powder after 50 h of heat treatment at 1300°C confirmed stabilization of zirconia in the t-prime phase with around 15 wt.% monoclinic impurity. Furthermore, FESEM results (before and after heat treatment) indicated orderly particles of uniform shape and size with a small tendency toward agglomeration.
A new class of unilateral variational models appearing in the theory of poroelasticity is introduced and studied. A poroelastic medium consists of solid phase and pores saturated with a Newtonian ...fluid. The medium contains a fluid-driven crack, which is subjected to non-penetration between the opposite crack faces. The fully coupled poroelastic system includes elliptic–parabolic governing equations under the unilateral constraint. Well-posedness of the corresponding variational inequality is established based on the Rothe semi-discretization in time, after subsequent passing time step to zero. The NLCP-formulation of non-penetration conditions is given which is useful for a semi-smooth Newton solution strategy.
This study investigated the two-body wear resistance of a first generation 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), a second generation 3Y-TZP, a third generation 4 mol% ...yttria partially stabilized zirconia (4Y-PSZ), a 5 mol% yttria partially stabilized zirconia (5Y-PSZ), and a type III gold alloy (Aurocast 8), performed using opposing antagonistic cusps made out of the same material. Eight cylindrical specimens were prepared for each material (n = 8) for a total of forty specimens (N = 40). Conical cusps were fabricated for each material. Each cylinder−cusp pair was arranged inside a two-axis chewing simulator over up to 360,000 loading cycles. The wear resistance was analyzed by measuring the vertical substance loss (mm) and the volume loss (mm3). The antagonist wear (mm) was recorded before and after the wear test to evaluate the linear difference. Statistical analysis was performed using one-way analysis of variance (ANOVA); multiple comparisons were performed according to Tukey’s method. No statistically significant differences (p > 0.05) among the first generation 3Y-TZP, second generation 3Y-TZP, and 4Y-PSZ wear were found. 5Y-PSZ showed statistically significant higher wear compared to other the zirconias. Aurocast 8 displayed the highest values in terms of vertical wear, antagonist cusp wear, and volumetric loss. Although still not statistically comparable, the wear behavior of the latest 5Y-PSZ was the closest to the widely recognized gold standard represented by the type III gold alloy.
Atovaquone belongs to a naphthoquinone class of drugs and is used in combination with proguanil (Malarone) for the treatment of acute, uncomplicated malaria caused by Plasmodium falciparum (including ...chloroquine-resistant P. falciparum/P. vivax). Numerous quinone-derived compounds have attracted considerable attention in the last few decades due to their potential in antimalarial drug discovery. Several semi-synthetic derivatives of natural quinones, synthetic quinones (naphtho-/benzo-quinone, anthraquinones, thiazinoquinones), and quinone-based hybrids were explored for their in vitro and in vivo antimalarial activities. A careful literature survey revealed that this topic has not been compiled as a review article so far. Therefore, we herein summarise the recent discovery (the year 2009–2020) of quinone based antimalarial compounds in chronological order. This compilation would be very useful towards the exploration of novel quinone-derived compounds against malarial parasites with promising efficacy and lesser side effects.
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•Quinone derivatives exhibit potent antimalarial activities against drug-sensitive and MDR-resistant P. falciparum strains.•This review covers the recent studies of in vitro and in vivo antimalarial activity (2009-2020) of quinone-based compounds.•This describes structural modifications at specified positions on quinones and their impact on antimalarial activity.•Toxicity and bioavailability issues suffered by quinones need to be addressed for the development of effective drugs.
The utilization of gas resources is a promising strategy with both economic and environmental benefits. With the development of exploration technology, the deep reservoir has become the main ...application direction of geological storage. However, it is challenging to quantitatively analyze the multiphase interaction and flow behavior of oil, water, and gas using microfluidic technology at 115 °C and 55 MPa. In this study, different gases (N2, CO2, hydrocarbon gas (HC)) were injected into the high-temperature and high-pressure (HTHP) microfluidic chip to analyze bubble dissolution, hydrodynamic dispersion, and droplet dynamics. The results show that HTHP on wettability leads to cross-distribution of oil-wet and water-wet surfaces, reducing the gas’s relative permeability. Nitrogen has a dissolution mechanism with interstitial dissolution and addition reaction. With CO2/HC injection, the dominant mechanism is gradually transformed from dissolution-condensate to extraction-vaporization. The deposited asphaltene gradually dissolves into a mobile liquid and its volume expansion rate exceeds 28.50 %. The displacement efficiency of N2, HC, and CO2 for residual oil in the microfluidic chip is 14.35 %, 29.38 % and 35.16 %, respectively. In the mobilization mechanism of CO2 recovery, immiscible displacement, extraction, and swelling account for 14.35 %, 16.68 % and 4.13 %, respectively. Hence, geological CO2 utilization and storage for oil production are recommended, especially in deep reservoirs.
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•Microfluidic device simulating 55 MPa and 115 ℃ is developed.•Interaction property of gas and deep oil is quantified from microscopic perspective.•Migration mechanism of multiphase flow in porous media is confirmed.•Successful practice provides geological CO2 utilization and storage in deep geological reservoir
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•A highly efficient photocatalyst ML-WO3/TiO2 was successfully prepared for the first time.•The 1 mol% ML-WO3/TiO2 sample reached 98.05% decomposition of MB within 10 min under solar ...irradiation.•The ML-WO3/TiO2 material maintained high stability after five cycle tests.•ML-WO3/TiO2 photocatalytic mechanism under solar consistent with Z-scheme heterojunctions.
Highly efficient photocatalysts were formed via high-temperature calcination of monolayer WO3 prepared by a space-constrained method combined with commercial TiO2, and the optimal ratio of these components was explored. These synthetic catalysts were also characterized. During photocatalysis, the decomposition rate of MB achieved by the 1 mol% ML-WO3/TiO2 composite reached 98.05% within 10 min under solar light. Moreover, the photocatalytic efficiency of the composite catalyst did not decrease substantially after 5 cycles of operation. In addition, energy band position and active gene capture experiments revealed that the prepared photocatalysts conform to the transfer theory of Z-scheme heterojunctions.
Polycrystalline La0.67(Ca0.27Sr0.06)MnO3:mol%Agx (LCSMO:Agx, x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were prepared by conventional sol-gel method. Effects of Ag-doping (x) on structures, surface ...morphologies, electrical and magnetic transport properties of the as-prepared LCSMO:Agx samples were evaluated. X-ray diffraction (XRD) showed that all samples crystallized in orthorhombic structures with Pnma space group. As x content increased, main diffraction peak (121) shifted downwards lower angles, giving rise to A site ions (Ca2+ or Sr2+) substitution by Ag+. This, in turn, caused slight expansion of the lattice and improved Mn4+ ion concentration. Meanwhile, grain size gradually increased and grain boundaries (GBs) reduced, the resistivity decreased and metal-insulator transition temperature (TMI) almost kept constant at room temperature. On the other hand, the magnetoresistance (MR) and temperature coefficient of resistance (TCR) increased during first stages and then decreased as x further rose. An optimum doping molar ratio of x = 0.2 was obtained, with room temperature MR and TCR reaching up to 44.5% and 22.5% K−1, respectively. Curve fitting results indicated that in low temperature ferromagnetic metallic (FM) region, conductive behavior of LCSMO:Agx was mainly related to electron-electron, electron-phonon, and electron-magnon scattering. In high temperature paramagnetic insulating (PI) region, data followed the small-polaron-hopping model. Conductive behavior in the entire temperature region was fitted with phenomenological equation under percolation approach, and found to depend on segregation of FM and PI phases. These findings suggest promising applications of LCSMO:Agx materials in photoelectric (uncooled bolometer or infrared detectors) or magnetic devices (uncooled magnetic sensors) at room temperature.
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