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1
Wu, Jianfeng, Zhichao Chen, Xiaohong Xu, Peng Wei, Guobin Xie e Xinyi Zhang. "The Growth Process and Photocatalytic Properties of h-MoO3 and α-MoO3 under Different Conditions". Crystals 13, n. 4 (1 aprile 2023): 603. http://dx.doi.org/10.3390/cryst13040603.
Testo completoAbstract (sommario):
In this experiment, we investigated the effects of different reactions on the growth process and morphology of h-MoO3 and α-MoO3, and their optical properties and photocatalytic activities were also investigated. Orthogonal experiments were designed to investigate the effects of four influencing factors, namely the amount of ammonium molybdate tetrahydrate (AHM), the type of acid, the reaction temperature and the holding time, on the morphology of h-MoO3 by a microwave hydrothermal method. The phase and morphology were analyzed by using advanced physicochemical techniques. The XRD results showed that the samples produced by the microwave hydrothermal method had sharp diffraction peaks, high crystallinity and complete crystalline shape. AHM generates h-MoO3 in both hydrochloric and nitric acid environments. In particular, when the temperature rises to 200 °C, the generated h-MoO3 will be converted to α-MoO3 in a nitric acid environment, which will be generated in a sulfuric acid environment. Therefore, increasing the reaction temperature will result in the conversion of h-MoO3 to α-MoO3 in sulfuric acid solution. SEM results show that the sample prepared from hydrochloric acid solution has a complete hexagonal prism morphology, while the sample prepared from sulfuric acid solution presents a long fibrous morphology, and the sample prepared from nitric acid solution has many defects on the surface of the hexagonal prism morphology. Interestingly, sample A11 prepared in nitric acid solution showed a spherical structure. Since the generated A3, A6 and A9 samples are all stable phase α-MoO3, they have a wider band gap compared with other samples. Their particle size is up to the nanometer scale, so they have strong adsorption properties. The spherical sample A11 has excellent adsorption and photocatalytic activity.
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Maniruzzaman, Md, Rahim Abdur, Md Abdul Kuddus Sheikh, Son Singh e Jaegab Lee. "Conductive MoO3–PEDOT:PSS Composite Layer in MoO3/Au/MoO3–PEDOT:PSS Multilayer Electrode in ITO-Free Organic Solar Cells". Processes 11, n. 2 (16 febbraio 2023): 594. http://dx.doi.org/10.3390/pr11020594.
Testo completoAbstract (sommario):
The solution-processed and conductive MoO3–PEDOT:PSS (Mo–PPSS) composite layer in a MoO3/Au/MoO3–PEDOT:PSS (MoAu/Mo–PPSS) multilayer electrode in ITO-free organic solar cells (OSCs) was optimized in terms of electrical conductivity, interfacial contact quality, work function, and process wettability of the conductive composite thin film. The surface composition of the PEDOT:PSS film onto different electrodes was observed by using X-Ray Photoelectron Spectroscopy. The PEDOT:PSS-MoO3 composite protects the dissolution of individual MoO3 with PEDOT:PSS, which was confirmed by Auger Electron Spectroscopy. The UV-Visible spectroscopy showed that the photoactive layer of P3HT:PCBM absorbs in the wavelength range of 300–650 nm with the maximum absorption at 515 nm (2.40 eV). The device performance of 3.97% based on an MoAu/Mo–PPSS conductive composite electrode exhibited comparable enhancement and only 6% enhancement compared to an ITO-based electrode (3.91%). The enhancement of device efficiency was mainly due to relatively higher conductivity, a low work function of the conductive metal oxide-metal-metal oxide/polymer composite, and an enhancement of interfacial contact quality between the hole transport layer (HTL) and the mixed organic polymeric photoactive layer. These results indicate that the solution-processable Mo–PPSS conductive composite layer of the MoO3/Au multilayer electrode can replace the ITO-based electrode in the bulk of heterojunction organic photovoltaics (OPVs).
3
BAI, SHOULI, SONG CHEN, YUAN TIAN, RUIXIAN LUO, DIANQING LI e AIFAN CHEN. "HYDROTHERMAL SYNTHESIS OF α-MoO3 NANORODS FOR NO2 DETECTION". International Journal of Nanoscience 11, n. 06 (dicembre 2012): 1240044. http://dx.doi.org/10.1142/s0219581x12400443.
Testo completoAbstract (sommario):
Thermodynamically stable molybdenum trioxide nanorods have been successfully synthesized by a simple hydrothermal process. The product exhibits high-quality, single-crystalline layered orthorhombic structure (α- MoO3 ), and aspect ratio over 20 by characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared (FT-IR). The growth mechanism of α- MoO3 nanorods can be understood by electroneutral and dehydration reaction, which is highly dependent on solution acidity and hydrothermal temperature. The sensing tests show that the sensor based on MoO3 nanorods exhibits high sensitivity to NO2 and is not interferred by CO and CH4 , which makes this kind sensor a competitive candidate for NO2 detection. The intrinsic sensing performance of MoO3 maybe arise from its nonstoichiometry of MoO3 owing to the presence of Mo5+ and oxygen vacancy in MoO3 lattice, which has been confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The sensing mechanism of MoO3 for NO2 is also discussed.
4
Zeng, Yi, Chaoping Liang, Yuanjun Sun, Na Wang, Xiangdong Ding e Jun Sun. "Effect of Mo Oxides on the Phase Composition and Characteristics of Mo-10Re Pre-Alloyed Powders Co-Reduced with NH4ReO4". Materials 16, n. 17 (30 agosto 2023): 5936. http://dx.doi.org/10.3390/ma16175936.
Testo completoAbstract (sommario):
Mo-Re pre-alloyed powders are crucial raw materials in fabricating Mo-Re alloys, and their properties can significantly impact the properties of the resulting alloys. The powders are usually produced by the co-reduction of a mixture of Mo and Re oxides. However, it remains unclear if the overall characteristics of the produced Mo-Re powders rely on the different combinations of the Mo and Re oxide precursors. Therefore, in this work, a comparative study is conducted on the co-reduction processes of different Mo oxides together with NH4ReO4, along with its influence on the size distribution and phase composition of the resulting Mo-10Re pre-alloyed powders. The results show that MoO3 is more promising than MoO2 as a precursor material. The powders fabricated using MoO3, when compared to MoO2, have a much more uniform size distribution, with a primary particle size ranging from 0.5–4 μm. In addition, it is also beneficial to achieve atomic-scale homogeneous mixing with Mo and Re elements and the formation of a solely Mo(Re) solid solution if MoO3 is used as a precursor oxide. In contrast, such desirable features were not identified when using the MoO2 route. The reason for this discrepancy may relate to whether Mo-O-Re metallurgical bonding has formed during the co-reduction process.
5
Eliseeva, E. A., S. L. Berezina e I. G. Gorichev. "Kinetics of Molybdenum Trioxide Dissolution in the Alkaline Medium". Herald of the Bauman Moscow State Technical University. Series Natural Sciences, n. 2 (107) (aprile 2023): 98–109. http://dx.doi.org/10.18698/1812-3368-2023-2-98-109.
Testo completoAbstract (sommario):
The paper presents experimental study results of the MoO3 powder samples dissolution kinetics in the aqueous ammonia solution at various pH concentrations and values. Molybdenum ions concentration in the filtrate samples was determined spectrophotometrically. Kinetic characteristics were obtained, and kinetic parameters (specific dissolution rate, reaction order with respect to the H+ ion) were calculated. It was established that the dissolution rate was increasing in the ammonia solution concentration range of 0.02--1.26 mol/l, and with the growing pH it passed through the maximum. Taking into account the acid-base equilibria constants, the dissolution process was simulated, and its stage-by-stage nature was established. Fractional reaction order with respect to the H+ ions calculated from the curves plotted in the α--t/t0.5 coordinates (affine transformation method) indicated the adsorption mechanism of dissolution. It was shown that the MoO3 dissolution proceeded with formation of the intermediate adsorption complexes. Due to the HMoO4- low concentration in the MoO3 concentration within the studied pH range by the surface-active particle, on which groups of ions were adsorbed, the MoO4- could be considered. The results obtained are an addition to the data possessed on the molybdenum oxide phase and other transitional metals behavior. They could be applied in the practical applications associated with dissolving molybdenum in the alkaline electrolytes
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Du, Xiaoni, Xiaohong Wang, Yang Liu e Peizhong Feng. "Spray solution combustion synthesis of hollow porous MoO3 photocatalyst". Ceramics International 45, n. 9 (giugno 2019): 12599–601. http://dx.doi.org/10.1016/j.ceramint.2019.03.168.
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Dhanabal, Rengasamy, Dhanasekaran Naveena, Sivan Velmathi e Arumugam Chandra Bose. "Reduced Graphene Oxide Supported Molybdenum Oxide Hybrid Nanocomposites: High Performance Electrode Material for Supercapacitor and Photocatalytic Applications". Journal of Nanoscience and Nanotechnology 20, n. 7 (1 luglio 2020): 4035–46. http://dx.doi.org/10.1166/jnn.2020.17779.
Testo completoAbstract (sommario):
Using a simple solution based synthesis route, hexagonal MoO3 (h-MoO3) nanorods on reduced graphene oxide (RGO) sheets were prepared. The structure and morphology of resulting RGO-MoO3 nanocomposite were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The optical property was studied using UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectroscopy (PL). The RGO-MoO3 nanocomposites were used as an electrode for supercapacitor application and photocatalyst for photodegradation of methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. We demonstrated that the RGO-MoO3 electrode is capable of delivering high specific capacitance of 134 F/g at current density of 1 A/g with outstanding cyclic stability for 2000 cycles. The RGOMoO3 photocatalyst degrades 95% of MB dye within 90 min, and a considerable recyclability up to 4 cycles was observed. The quenching effect of scavengers test confirms holes are main reactive species in the photocatalytic degradation of MB. Further, the charge transfer process between RGO and MoO3 was schematically demonstrated.
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Ioakeimidis, Apostolos, Alina Hauser, Michael Rossier, Flavio Linardi e Stelios A. Choulis. "High-performance non-fullerene acceptor inverted organic photovoltaics incorporating solution processed doped metal oxide hole selective contact". Applied Physics Letters 120, n. 23 (6 giugno 2022): 233301. http://dx.doi.org/10.1063/5.0091671.
Testo completoAbstract (sommario):
Inverted organic photovoltaics (OPVs) allow flexibility on designing a roll-to-roll production process of OPVs, providing technological opportunities. The OPV roll-to-roll production process demands thick and high-performance solution-based hole selective contacts. Here, we show that a solution processed antimony-doped tin oxide (ATO) hole selective contact produced by spray pyrolysis route exhibits exceptional optoelectronic properties and functionality within non-fullerene acceptor PM6:Y6:PC70BM inverted OPVs. The corresponding solution processed inverted OPVs provide high power conversion efficiency values when a thick hole selective contact of solution processed doped ATO is incorporated within the inverted OPV device structure and similar light stability to that achieved with the commonly used thermally evaporated MoO3 hole selective contact.
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Nagar, Mangey Ram, Rohit Ashok Kumar Yadav, Deepak Kumar Dubey e Jwo-Huei Jou. "Solution Process Feasible Highly Efficient Organic Light Emitting Diode with Hybrid Metal Oxide Based Hole Injection/Transport Layer". MRS Advances 4, n. 31-32 (2019): 1801–9. http://dx.doi.org/10.1557/adv.2019.300.
Testo completoAbstract (sommario):
ABSTRACTOrganic light emitting diodes (OLEDs) have drawn great attention owing to their potential applications in high-quality flat display panels and smart solid-state lighting. Over the last three decades, numerous approaches have been made on material design and device physics to achieve high-efficiency and long-lifespan. Herein, we report a novel tactic to employ solution-processed hybrid metal oxide, molybdenum trioxide-tungsten trioxide (MoO3:WO3), as an efficient and stable hole injection/transport (HIL/HTL) and electron blocking layer for efficient OLEDs. By using phosphorescent orange-red emitter tris(2-phenylquinoline)-iridium(III) Ir(2-phq)3, MoO3:WO3 HIL based OLED device exhibits a power efficiency of 27.7 lm W-1 and 22.9 lm W-1 at 100 and 1000 cd m-2, respectively, which are 89% and 157% higher than that of conventional OLED device consisting of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as an HIL. Moreover, the resulted device also displays 1.6 times lower turn-on voltage and 3.0 time higher brightness as compare to other counter part. The higher device performances of OLED device may be attributed to robust hole transporting ability, balanced charge carrier in the recombination zone and non-acidic nature of designed HIL. Our results demonstrate that a novel alternative approach based on transition metal oxide hybrid HIL/HTL as a substitute to PEDOT:PSS for high-efficiency solution process OLEDs.
10
Pacco, Antoine, Teppei Nakano, Shota Iwahata, Akihisa Iwasaki e Efrain Altamirano Sanchez. "Etching of molybdenum via a combination of low-temperature ozone oxidation and wet-chemical oxide dissolution". Journal of Vacuum Science & Technology A 41, n. 3 (maggio 2023): 032601. http://dx.doi.org/10.1116/6.0002404.
Testo completoAbstract (sommario):
Etching of molybdenum was demonstrated in two steps. Mo was first oxidized in an ozone gas ambient to form molybdenum oxide. It is shown that comparable oxide thicknesses can be obtained in ozone and oxygen but at lower temperatures for the former. Initial oxide growth is fast but then considerably slows down due to its diffusion-limited character. The metal-oxide thickness can be controlled by temperature and defines the amount of metal etch per cycle (EPC). XPS analysis showed that the thermally grown oxide is MoO3. In the second, wet-chemical step, MoO3 was dissolved selectively toward the Mo metal using an aqueous solution. The dissolution rate of amorphous MoO3 formed in O3 at temperatures below ∼230 °C is fast, but the dissolution of MoO3 formed at Tox > 230 °C was shown to be incomplete. Cross-section TEM showed a matrix of amorphous oxide with crystallized MoO3 islands, the latter more difficult to dissolve. However, the crystalline phase could be completely and selectively removed using a more concentrated NH4OH solution at an elevated temperature (70 °C). The EPC was determined for temperatures between 150 and 290 °C. The etch rates increased with temperature from 1–2 nm/cycle at 150 °C to 5–6 nm/cycle at 290 °C. This hybrid thermal-wet etching sequence is well suited for vertical and lateral recess etching as it shows a controlled and isotropic dissolution of polycrystalline Mo at the nanoscale. Furthermore, the process shows a progressive surface smoothening upon increasing the number of etching cycles.
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Vedyagin, Alexey A., Anton Koskin e Ilya Mishakov. "In search of efficient catalysts and appropriate reaction conditions for gas phase nitration of benzene". Resource-Efficient Technologies, n. 3 (19 settembre 2016): 118–25. http://dx.doi.org/10.18799/24056529/2016/3/56.
Testo completoAbstract (sommario):
The present paper is dedicated to the development of a method for the nitrobenzene production using solid acid catalysts, as an alternative to industrial nitration, based on a mixture of concentrated acids. The influence of key parameters of the nitration process (temperature, reagent flow rate, nitrating agent concentration etc.) on the conversion of the initial substrate, the degree of decomposition of nitric acid and the quantity ofresulting oxygenates was studied. Recommendations for the selection of effective catalytic systems (high content of Brønsted acid sites with Ho < −4, high specific surface and resistance to HNO3) were developed and the best conditions for process reactions (temperature 200 °C, aqueous solution of nitric acid with concentration of 30 wt%, “nitric acid:benzene” ratio = 0.76) were found. A method for regeneration of the catalytic activity without unloading the catalyst was proposed. As an example, MoO3/SiO2 sample was tested in a dual-mode nitration/regeneration process, which allowed us to increase the flow rates of reagents and obtain catalyst efficiency of up to STY = 4.09 g/(gcat · h). Several of the most promising catalysts (MoO3/SiO2, WO3/ZrO2 and Nafion/support composite) for the process were tested in identical conditions.
12
DOĞAN, Kemal, Ali Akbar HUSSAINI, Mehmet Okan ERDAL e Murat YILDIRIM. "Examining the hydrophobic properties of electrospun oxide-induced polystyrene nanofibers for application in oil-water separation". International Advanced Researches and Engineering Journal 6, n. 2 (under construction) (15 agosto 2022): 100–105. http://dx.doi.org/10.35860/iarej.1075031.
Testo completoAbstract (sommario):
Nanofibers have great importance in the membrane technology used in hydrophobic surface filtration studies applied to water-oil separation products. This study improves upon the hydrophobic properties of electrospun polystyrene-based nanofibers by increasing surface contact angles. As a result, nanofibers have been produced by adding ZnO, MoO3, NiO, SiO2, and TiO2 additives to the polystyrene (PS)/dimethylformamide (DMF) polymer solution at 5% of the mass. Surface contact angle (CA), fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) images of the nanofibers were taken. The obtained results were evaluated and show the fiber diameter to range from 555 to 1553 nm. The addition process was observed to be able to affect the polystyrene fiber’s ability to retain water. Moreover, surface contact angle of polystyrene increased to 143° by TiO2 addition. Furthermore, the highest oil-carrying capacity is concluded to have been observed on the SiO2 and MoO3 doped fibers.
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Lee, Min-Hsuan, Lixiang Chen, Ning Li e Furong Zhu. "MoO3-induced oxidation doping of PEDOT:PSS for high performance full-solution-processed inverted quantum-dot light emitting diodes". J. Mater. Chem. C 5, n. 40 (2017): 10555–61. http://dx.doi.org/10.1039/c7tc03700g.
Testo completoAbstract (sommario):
MoO3-induced oxidation in PEDOT:PSS hole contact enables improving its conductivity, work function and process compatibility for application in solution-processed transparent QD-LEDs, attaining a maximum luminous efficiency of 1.39 cd A−1and a transparency of >70%.
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Kannan, B., R. Pandeeswari e B. G. Jeyaprakash. "Influence of precursor solution volume on the properties of spray deposited α-MoO3 thin films". Ceramics International 40, n. 4 (maggio 2014): 5817–23. http://dx.doi.org/10.1016/j.ceramint.2013.11.022.
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Gurskii, A. L., N. A. Kalanda, M. V. Yarmolich, I. A. Bobrikov, S. V. Sumnikov e A. V. Petrov. "PHASE TRANSFORMATIONS DURING CRYSTALLIZATION OF A SOLID SOLUTION OF STRONTIUM-SUBSTITUTED DOUBLE PEROVSKITE". Doklady BGUIR, n. 7-8 (29 dicembre 2019): 73–80. http://dx.doi.org/10.35596/1729-7648-2019-126-8-73-80.
Testo completoAbstract (sommario):
The kinetics of phase contents modification in the process of SrBaFeMoO6–δ crystallization from a stoichiometric mixture of SrCO3 + BaCO3 + 0,5Fe2O3 + MoO3 simple oxides using the solid phase method has been investigated. In the temperature region of 300–1200°С, a number of endotermic effects have been detected. Herewith, the first one (with maximum around 552°С) and the third one (with maximum around 743°С) are accompanying by the significant decrease of the mass of specimen. In the temperature range of 946–1200°С, the mass change of specimen is practically not observable, while the thermal effect is still present, and the specimen remains not single-phase one. This indicates the difficulty of the flow of solid phase reactions with the formation of solid solution of barium-strontium ferromolybdate. During analysis of the change of the phase composition consisting of a mixture of initial reagents of stoichiometric relation SrCO3 + BaCO3 + 0,5Fe2O3 + MoO3, it has been observed that with increasing temperature, complex compounds BaMoO4, SrFeO3 appear almost simultaneously, then SrBaFeMoO6–δ appears consequently. Thus, the compounds BaMoO4 и SrFeO3, are structure forming for the solid solution of barium-strontium ferromolybdate. With further temperature increase up to 770°С the formation of new compound ВаFeO3 with disappearing SrFeO3 was detected. In this case, the amount of double perovskite increases faster than that of barium molybdate. The main accompanying compounds at the crystallization of the SrBaFeMoO6–δ double perovskite solid solution are BaMoO4 and SrFeO3. It was established that at the initial stage of the interaction, the resulting solid solution of barium-strontium ferromolybdate is enriched with iron and its composition changes during the reaction in the direction of an increase of the molybdenum content, as in the case of other precursor combinations.
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Abla, Fatima, Yehya Elsayed, Nedal Abu Farha, Khaled Obaideen, Ahmed A. Mohamed, Haesung Lee, Changseok Han, Mehmet Egilmez e Sofian Kanan. "Fabrication of High Surface Area TiO2-MoO3 Nanocomposite as a Photocatalyst for Organic Pollutants Removal from Water Bodies". Catalysts 13, n. 2 (7 febbraio 2023): 362. http://dx.doi.org/10.3390/catal13020362.
Testo completoAbstract (sommario):
A nanocomposite (NC) of titanium (IV) oxide (TiO2) and molybdenum (VI) oxide (MoO3) was synthesized using a hydrothermal route. Detailed analyses using transmission electron microscopy, X-ray diffraction, X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) isotherms, X-ray photoelectron spectroscopy, Raman, and diffuse reflectance infrared Fourier transform spectroscopy were carried out and confirmed the successful formation of pure TiO2-MoO3 (Ti-Mo) NC. The Ti-Mo NC possesses sizes in the range of 150–500 nm. XPS, Raman, and DRIFT shift measurements confirmed the formation of mixed oxide linkage in the form of Ti-O-Mo. Sorption of nitrogen isotherms revealed a significant increase in the number and pore widths of mesopores in the NC. Water sorption isotherms revealed enhanced affinity of the nanocomposites for water relative to the pure metal oxides. The BET surface area for Ti-Mo NC from the nitrogen adsorption isotherm was 129.3 m2/g which is much higher than the pure metal oxides (i.e., 37.56 m2/g for TiO2 and 2.21 m2/g for MoO3). The Ti-Mo NC provided suitable adsorption sites that captured the studied carbamates from the solution and promoted their photodegradation process. The photocatalytic degradation of MB in the presence of the catalyst was enhanced by 2.9 and 5.5 folds upon irradiation with white LED and 302 nm UV light sources, respectively.
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Selvan, P., D. J. J. Jebaraj e N. R. J. Hynes. "Pulsed laser deposition of ZnO and MoO3 as reflection prohibitors on photovoltaic cell substrate to enhance the efficiency". Journal of Achievements in Materials and Manufacturing Engineering 113, n. 2 (1 agosto 2022): 65–71. http://dx.doi.org/10.5604/01.3001.0016.1414.
Testo completoAbstract (sommario):
With the ever-growing demand for conventional fuels, the improvement in the efficiency of the photovoltaic system is the need of the hour. Antireflection coatings enhance the availability of solar power by reducing the percentage of light reflected. A new coating has been developed to improve the solar cell's overall efficiency. This study focuses on enhancing the efficiency of the monocrystalline solar cell when a coating of ZnO-MoO3 is applied at a certain thickness. A layer of ZnO followed by MoO3 is deposited on a Silicon solar cell substrate using a Pulsed Laser Deposition process. Due to the transmissivity d between the two materials, they act as excellent antireflection coating. The layer thickness has been engineered to lie in the maximum absorption spectrum of monocrystalline silicon solar cells, which is between 400 and 800 nanometers. Based on the calculation of transmissivities for a given layer thickness of coating material, the coating has been done, and the efficiencies of the coated specimen were compared with the uncoated solar cell. The percentage improvement in the electrical efficiency of a single crystalline silicon solar cell with an anti-reflection coating at 1059 W/m2 is about 35.7%. Among the available antireflection coating materials, the combination that provides better efficiency when coated on top of a solar cell is hard to find. This anti-reflection coating could be a better solution to enhance the overall efficiency of the single crystalline silicon solar cell. Although ZnO and MoO3 coatings have been investigated separately for improvement in solar cell efficiency with varying levels of success, the hybrid coating of ZnO/MoO3 with a performance enhancement of 35.7% is a great leap.
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Mizushima, Takanori, Kazuya Fukushima, Hironobu Ohkita e Noriyoshi Kakuta. "Synthesis of β-MoO3 through evaporation of HNO3-added molybdic acid solution and its catalytic performance in partial oxidation of methanol". Applied Catalysis A: General 326, n. 1 (30 giugno 2007): 106–12. http://dx.doi.org/10.1016/j.apcata.2007.04.006.
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Khoshnevisana, A., e H. Yoozbashizadeha. "Determination of optimal conditions for pressure oxidative leaching of Sarcheshmeh Molybdenite concentrate using Taguchi method". Journal of Mining and Metallurgy, Section B: Metallurgy 48, n. 1 (2012): 89–99. http://dx.doi.org/10.2298/jmmb110308003k.
Testo completoAbstract (sommario):
The present research work is based on finding the optimum conditions for pressure oxidative leaching of the molybdenite concentrate to produce technical-grade molybdic oxide (MoO3) with high recovery through further treatment of the filtrate solution. The Taguchi method was used to design and minimize the number of experiments. By using Taguchi orthogonal (L25) array, five parameters (time, temperature, oxygen pressure, pulp density and acid concentration) at five levels were selected for 25 experiments. The experiments were designed and carried out in a high-pressure reactor in the presence of nitric acid as solvent and oxidizing agent for the molybdenite concentrate and its ReS2 content. The optimum conditions for pressure leaching of molybdenite were obtained through using Signal to Noise analysis and modified by using Minitab software prediction tool. Furthermore, the optimum condition for an economical pressure leaching of rhenium sulfide (ReS2) was achieved with the same process. Analysis of variance (ANOVA) showed that the pulp density is of paramount importance in this process.
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Fu, Ming, S. Penumella e J. A. Sekhar. "Micropyretic synthesis of MoSi2 powders through an aluminothermic reaction". Journal of Materials Research 14, n. 5 (maggio 1999): 2023–28. http://dx.doi.org/10.1557/jmr.1999.0273.
Testo completoAbstract (sommario):
An aluminothermic reaction starting with inexpensive MoO3, SiO2, and Al powders was utilized to prepare molybdenum disilicide (MoSi2) powders by the micropyretic/combustion synthesis process and leaching. The combustion-synthesized product was porous and could readily be crushed into powders. X-ray diffraction (XRD) analysis revealed that the product of such a reaction consisted of α–Al2O3, MoSi2, and a small amount of Mo(Si,Al)2 and Mo5Si3. The reason for the formation of Mo(Si, Al)2 phase is discussed. MoSi2 powders were obtained by leaching out the Al2O3 from the synthesized powder mixtures in boiling phosphoric acid solution. The synthesized MoSi2 powders, including a small amount of Mo(Si, Al)2 and Mo5Si3, were very fine with an average particle size of about 1 μm.
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Xing, Hai-Rui, Ping Hu, Chao-Jun He, Xiang-Yang Zhang, Fan Yang, Jia-Yu Han, Song-Wei Ge et al. "Exploring the Formation Mechanism, Evolution Law, and Precise Composition Control of Interstitial Oxygen in Body-Centered Cubic Mo". Metals 13, n. 1 (20 dicembre 2022): 1. http://dx.doi.org/10.3390/met13010001.
Testo completoAbstract (sommario):
Interstitial oxygen (O) on the formation mechanism and enrichment distribution of body-centered cubic (BCC) molybdenum (Mo) has rarely been reported, and the O usually can cause serious brittle fracture in Mo. In this paper, we studied the formation mechanism and evolution of oxygen (O) when it was precisely controlled in the range of 3700–8600 parts per million (wppm). It was found that, with an increase in O concentration, O element not only existed in the form of solid solution but generated O element with different valence states in Mo metal. Large amounts of MoO2, MoO3, and Mo4O11 intermediate oxides were identified by electron probe micro-analyzer (EPMA) and X-ray photoelectron spectroscopy (XPS). Thermodynamic calculations revealed the formation process of oxides, and authenticity of the presence of O was verified by XPS. Enrichment and distribution of O element were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and EPMA. Moreover, the compressive yield strength and hardness of Mo were greatly affected by O content range of 4500–8600 wppm. Our study is helpful to understand the behavior of interstitial impurity O in refractory Mo metals and provides important guidance for development of high-purity rare Mo metals.
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Xhaferaj, Nertil, Nicolò M. Ippolito, Fabio Maggiore e Francesco Ferella. "Extraction and Recovery of Metals from Spent HDS Catalysts: Lab- and Pilot-Scale Results of the Overall Process". Metals 12, n. 12 (15 dicembre 2022): 2162. http://dx.doi.org/10.3390/met12122162.
Testo completoAbstract (sommario):
The present study proposes an overall recycling process for spent hydrodesulfurization (HDS) catalysts. These catalysts contain valuable metals like cobalt (Co), molybdenum (Mo), nickel (Ni), and vanadium (V). In particular, one Co-Mo catalyst was treated in order to optimize the roasting step (time, soda ash, and temperature) at a pilot scale and thus maximize the extraction yield of molybdenum (Mo) and vanadium (V). In particular, a dry Co-Mo catalyst was used. After roasting at 700 °C for 2.5 h, the best conditions, the catalysts underwent water leaching, separating Mo and V from Co and the alumina carrier, which remained in the solid residue. The pregnant solution was treated to remove arsenic (As) and phosphorus (P), representing the main impurities for producing steel alloys. V was precipitated as NH4Cl, and further calcined to obtain commercial-grade V2O5, whereas Mo was recovered as molybdic acid by further precipitation at a pH of around one. Thus, molybdic acid was calcined and converted into commercial-grade MoO3 by calcination. The hydrometallurgical section was tested on a lab scale. The total recovery yield was nearly 61% for Mo and 68% for V, respectively, compared with their initial concentration in the spent Co-Mo catalysts.
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Utami, Lucky Indrati, Tahan Simamora Rizaldi, Kindriari Nurma Wahyusi e Reva Edra Nugraha. "The Utilization of Lapindo Mud Waste for Aluminium Sulfate Production". International Journal of Eco-Innovation in Science and Engineering 2, n. 02 (17 novembre 2021): 14–19. http://dx.doi.org/10.33005/ijeise.v2i02.40.
Testo completoAbstract (sommario):
The Lapindo mudflow disaster in East Java Province, or also known as LUSI (LUmpur “mud”-SIdoarjo) has become spectacular longest ongoing disaster in recent memory since 2006. The utilization of volcanic Lapindo mud could be the promising solution to prevent further environmental damage. The chemical composition of Lapindo mud contained of 44.1% SiO2, 23.7% Fe2O3, 13% Al2O3, 7.02% CaO, 5.35% MoO3, 2.53% K2O, 1.84% TiO2 and 0.7% Na2O. Aluminium sulfate (Al2(SO4)3) or “alum” have been widely used as coagulation compound in water treatment, paper and textiles industry. Aluminium sulfate can be synthesized from aluminium oxide (Al2O3) from Lapindo mud with acidic solutions (H2SO4). The aim of this work was to synthesize aluminum sulfate from Lapindo mud by using extraction process. The impact of H2SO4 concentration and heating time to the production of aluminium sulfate have been investigated. The results showed that the aluminium sulfate can be synthesized from Lapindo mud by using H2SO4. Based on XRF analysis, the variation of heating time and H2SO4 concentration affect the aluminium sulfate conversion. The increasing of heating time and H2SO4 concentration directly enhance the conversion until reach the optimum condition. The optimum condition for aluminium sulfate synthesis from Lapindo mud (75.78% conversion) was found to be 90 min for heating time with H2SO4 concentration of 80%
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Choi, Woon-Seop, e Thi Thu Thuy Can. "2D MoS2 Pattern from Sol-Gel-Processed Precursors Using Jet Printer for TFT Application". ECS Meeting Abstracts MA2022-02, n. 35 (9 ottobre 2022): 1293. http://dx.doi.org/10.1149/ma2022-02351293mtgabs.
Testo completoAbstract (sommario):
Molybdenum disulfide (MoS2) is one of the most studied layered TMDCs due to its excellent optical, electrochemical, and electrical properties. Monolayer MoS2 is a semiconductor with a direct band gap of 1.8 eV, but it has an indirect band gap in its bulk form, and make it possible to use 2D materials in the next generation of switching and optoelectronic devices. Many research groups have attempted to synthesize MoS2 with different methods to make good MoS2 quality. Mechanical exfoliation has been known as an uncomplicated way for flakes extracted from single crystals. However, several restrictions that method had to come up with were small and random flake size then extreme difficulty in the alignment for device fabrication. Chemical vapor deposition (CVD) have been used to prepare MoS2 thin layers in large scale. Nevertheless, this method demanded vacuum, the use of Mo or MoO3 thin films as precursors included in four-step CVD process for reduction and sulfurization resulted in expensive MoS2 films. Solution based methods, by contrast, is promising for large area formation of controllable MoS2 film with simple equipment, time-saving at low cost. No report has been published using jet printing technology from MoS2 precursor solution but our group. Therefore, the goal of this research was to develop a new drop-on demand printing method for MoS2 atomic layers based on sol-gel synthesis method. We developed a unique solution process to obtain large-size and uniform MoS2 atomic layers without CVD. The sulfurization process is omitted to simplify the entire process, and wafer-scale and larger-scale synthesis of MoS2 can be achieved by simple thermal treatment. The atomic layers of the synthesized MoS2 were identified as 2 layers, 3 layers, and 5 layers for MoS2 concentrations. MoS2 patterns were made with highly uniform coverage using electrohydrodynamic (EHD)-jet printing for the first time. The EHD jet-printed MoS2 TFTs show good electrical properties of 19.4 cm2 V-1 s-1.
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Yoo, Kyoungkeun, Won Beom Koo, Hanggoo Kim e Sang-hun Lee. "The Self-Reduction during the Thermal Decomposition of an Ammonium Molybdate". Minerals 13, n. 2 (17 gennaio 2023): 133. http://dx.doi.org/10.3390/min13020133.
Testo completoAbstract (sommario):
In the hydrometallurgical process of molybdenum using ammonia solution, ammonium paramolybdate tetrahydrate (APT: (NH4)6Mo7O24·4H2O) is produced as an intermediate product after a crystallization step. ATP is then thermally decomposed at a high temperature to give MoO3, which is reduced by hydrogen gas in a two-stage process to reduce molybdenum metal powder as the final product. If APT is pre-dried at an appropriately low temperature to remove the crystal water corresponding to 4 mol per mol of APT, it changes into (NH4)4Mo5O17, and the content of residual ammonia, which can be utilized as a reductant, in the ammonium molybdate increases. In this regard, the self-reducing potential of (NH4)4Mo5O17 was examined in this study through the effectiveness analysis of the residual ammonia component as a reductant for the primary hydrogen reduction step. In a series of experimental work on the thermal decomposition of (NH4)4Mo5O17 in an inert atmosphere, a maximum self-reduction degree of 18% was achieved. Based on this result, it can be expected that the metal powder can be manufactured in a more effective way than conventional processes in terms of hydrogen consumption and reaction time.
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Lo, Ming-Hung, Feng-Huei Cheng e Wen-Cheng J. Wei. "Preparation of Al2O3/Mo nanocomposite powder via chemical route and spray drying". Journal of Materials Research 11, n. 8 (agosto 1996): 2020–28. http://dx.doi.org/10.1557/jmr.1996.0254.
Testo completoAbstract (sommario):
A route to prepare nanometer-sized Mo particulates in Al2O3 was attempted by a combination of solution reactions in molecular scale and forcing precipitation by a spray-drying technique. MoO3 was first dissolved in ammonia water and then added in the slurry with high purity, submicrometer Al2O3 powder. Mixed suspension was spray-dried, and then the dried granules were reduced by hydrogen gas and further hot-pressing to a bulky composite at various temperatures. Dissolution of Mo oxide, adsorption reactions on the alumina surface, and surface potential of alumina particles in homogeneous ammonia suspension were studied. Characterization of the granules, including compactability, flowing properties, surface morphology, grain growth of Mo and Al2O3, and mixing homogeneity, were examined. Homogeneity of the spray-dried granules was determined by the calculation of mixing index and the observation of the microstructure of the sintered body. The existence of intergranular, intragranular, and nanosized Mo particulates within Al2O3 grains was observed by transmission electron microscopy (TEM). All the evidence revealed that homogeneous composites with nanometer-sized Mo had been successfully prepared by this attempt with the proposed chemical roue and following the spray-drying process.
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Escobar, Beatriz, Sara Lbarra, Adriana Reyes, Ysmael Verde, Romeli Barbosa, Ana Valenzuela e José Melo. "Síntesis y caracterización de materiales nanoestructurados de Ni y Mo depositados sobre bentonita". Quimica Hoy 4, n. 3 (30 settembre 2014): 5. http://dx.doi.org/10.29105/qh4.3-218.
Testo completoAbstract (sommario):
Recently, clay has been accepted as excellent adsorbents, catalyst, fillers in industry. The wide usefulness of bentonite is essentially as a result of its high specific surface area, high chemical and mechanical stabilities, and a variety of surface and structural properties. Nickel and molybdenum nanoparticles with particle size distribution ranging between 30-50 nm were synthesized by chemical reduction of ions using nickel nitrate hexahydrate (Ni(NO3)6.6H2O) and ammonium molybdate tetrahydrate (NH4)6Mo7O24.4H2O) in methanol solution, respectively. The process for reducing Pt nanoparticles was carried out in presence of NaBH4, Poly(N-vinylpyrrolidone) was used as protecting agent of the obtained particles. The synthesis process was performed at room temperature. The colloidal dispersions of Ni and M were supported on bentonite by impregnation method, and then were dried at around l00ºC until the solution was completely evaporated. The anchoring of Ni and Mo nanoparticles on the bentonite surface was carried out by a thermal process in a tubular furnace adapted with a quartz tube, where samples were annealed at 400ºC under nitrogen atmosphere for 30 min with a flow rate of 50 ml min-1. The obtained samples were chacterized using X-ray diffractometer (XRD), scanning electron microscope (SEM) and X-ray energy dispersive spectrormeter (EDS). In X-rays analysis for Ni sample was possible to observe peaks of metallic Ni and formation of NiO2, where as for molybdenum appeared diffraction peaks corresponding to the phases of Mo and MoO3. Through SEM waS possible to observe the morphology of the sample and Incorporation of the metal nanoparticles of Ni and Mo, Impregnated on the support. The characterization also reveals the well disperse of these obtained Ni and Mo nanoparticles supported on the external surface of clay with roughly spherical morphology and mean diameter of 30 nm. Finally, using the EDS technique was possible to estimate the actual load on bentonite catalysts.
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Shao, Yan Hai, Ming Ming Li e Xiong Tong. "Extraction of Vanadium in the Comprehensive Recycling of Spent Al2O3-Based Catalyst". Advanced Materials Research 634-638 (gennaio 2013): 3216–21. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.3216.
Testo completoAbstract (sommario):
Under the premise of comprehensive recycling valuable metals, a novel technology was developed to extract vanadium from spent Al2O3-based catalyst. Mixture of spent catalyst and sodium carbonate was roasted at 1000°C for 30 min with the mol ratio of Na2O to (Al2O3 + V2O5 + MoO3) as 1.15, after water leaching, 97.3% of vanadium could be extracted. With CaO addition of 25 g/L and reacting at 90°C for 4 h, 98.6% of vanadium in sodium aluminate solution was precipitated as desilication residue. The desilication residue was leached at 80°C for 45 min with sodium bicarbonate concentration of 100 g/L and L/S of 4 mL/g, over 96.4% of vanadium could be leached. By two purification steps with addition of 30 wt.% H2SO4 and Mg(NO3)2, respectively, over 99% of Al, 96% of Si, 93% of P and 95% of As were removed from leach liquor. Adding 50 g/L NH4NO3 to the purified leach liquor and adjusting pH to 8.2, 99.8% of vanadium could be precipitated as ammonium metavanadate. After calcination, the purity of V2O5 product was 98.25%. In the whole process, up to 88.7% of vanadium could be recovered from the spent catalyst.
29
Sakhnenko, Mykola, Iryna Stepanova, Svitlana Zyubanova, Anatoly Djenyuk e Sergey Indykov. "Photocatalytic activity of oxide systems based on doped d-elements of titanium alloys". Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, n. 3(9) (18 ottobre 2021): 97–102. http://dx.doi.org/10.20998/2413-4295.2021.03.14.
Testo completoAbstract (sommario):
CO-, W-, MO- and Zn-containing hetero-oxide nanostructured coatings on titanium and its alloys formed by plasma-electrolyte oxidation in galvanostatic mode from alkaline electrolytes were investigated. The morphology of the surface of the formed coatings was studied by scanning microscopy on the Zeiss Evo 40XVP microscope. The phase composition of the obtained coatings was determined on the X-ray diffractometer Drone-2. Photocatalytic activity of ZnO-WO3/TiO2 films, ZnO-MOO3/TIO2, ZnO-Co3O4/TiO2, CoO-WO3/TiO2 tested in a model reaction of decomposition of an aqueous solution of azobye with a concentration of 12,2·10-5 mol/L (MО) at UV irradiation. It is shown that with plasma-electrolyte oxidation of titanium and its alloys in alkaline diphosphate electrolytes in the mode of «drop-down power» forming heterostructural composites with micro-globular surface morphology. The possibility of controlling the phase and elemental composition of oxide layers, as well as the topography of the surface by changing the composition of the electrolyte and the content of individual components, as well as the modes of formation is confirmed. Heteroxide coatings formed in PEO modes differ in composition and surface morphology, but all exhibit photocatalytic properties of varying degrees of activity. The study of the photocatalytic activity of the obtained coatings in the azo dye decomposition reaction by means of UV testing allowed to rank the heteroxide systems according to the specified parameter. Thus, the degree of decomposition of MF on ZnO-WO3/TiO2 films in 50 minutes was 23 %. Metal oxide systems ZnO-Co3O4/TiO2 had similar characteristics of the degree of decomposition – 21 %. The incorporation of CoO and WO3 oxides into the coating composition reduced the catalytic activity of the system to 19 %. The unstable mode of formation of ZnO-MoO3/TiO2 oxides and the low speed of the process have affected the quality of the catalytic coating activity, reduced the degree of decomposition of MO to values of titanium monoxide Ti/TiO2 without dopants. Comparison of quantitative characteristics of the properties of the obtained coatings allowed to determine the effects of dopants, incorporated into metal oxide systems, on their photocatalytic activity.
30
Norouzi, Nazgol, Darrell Omo-Lamai, Timofey Averianov, Farbod Alimohammadi e Ekaterina Pomerantseva. "Molybdenum Oxide/Dopamine-Derived Carbon Electrodes with Enhanced Electrochemical Activity in Energy Storage Systems". ECS Meeting Abstracts MA2022-02, n. 2 (9 ottobre 2022): 137. http://dx.doi.org/10.1149/ma2022-022137mtgabs.
Testo completoAbstract (sommario):
Herein, a versatile sol-gel reaction produces new electrode materials consisting of tightly integrated molybdenum oxide and carbon derived from chemically incorporated dopamine molecules, and the materials show enhanced electrochemical activity in nonaqueous Li-ion and aqueous Zn-ion energy storage systems. The novel synthesis entails the oxidation of molybdenum in aqueous solutions of excess and limited dopamine (Dopa) hydrochloride via a hydrogen peroxide-initiated process. The transformation of molybdenum under the condition of Dopa excess (Mo:Dopa molar ratio of 1:1) resulted in the formation of a metastable precipitate of polydopamine (PDopa) spheres encapsulated by Dopa-preintercalated molybdenum oxide, (Dopa)xMoOy@PDopa. Hydrothermal treatment (HT) of (Dopa)xMoOy@PDopa precursor was concomitant with concurrent Dopa carbonization and molybdenum reduction processes, resulting in a formation of spherical matrices of Dopa-derived carbon decorated by MoO2 nanoplatelets (HT-MoO2/C), as determined through FTIR spectroscopy, Raman spectroscopy, and SEM imaging. Annealing (An) of HT-MoO2/C at 600°C under argon atmosphere (AnHT-MoO2/C) led not only to improvements in MoO2 crystallinity, but also to an increased oxidation state of molybdenum and a facilitated interaction between molybdenum-based and Dopa-derived components, resulting in an intimate MoO2/C heterointerface. Consequently, while both HT-MoO2/C and AnHT-MoO2/C showed reversible intercalation-type behavior when evaluated as electrodes versus Li/Li+ in nonaqueous lithium-ion cells, AnHT-MoO2/C demonstrated higher capacities, enhanced capacity retention, better rate capability, and lower charge transfer resistance. The AnHT-MoO2/C electrode showed an initial specific capacity of 260 mAh/g and 67% capacity retention after 50 cycles at 10 mA/g, compared to an initial specific capacity of 235 mAh/g and 47% capacity retention shown by HT-MoO2/C at the same current density. Furthermore, in rate capability experiments, HT-MoO2/C and AnHT-MoO2/C delivered specific capacities of 93 mAh/g and 120 mAh/g respectively at 100 mA/g. When molybdenum was transformed in the presence of Dopa deficit (Mo:Dopa molar ratio of 5:1), a (Dopa)xMoOy powder precursor was isolated, and subsequent hydrothermal treatment of this precursor produced an MoO3 material with carbonized Dopa molecules, HT-MoO3/C. Reference α-MoO3 electrodes (α-MoO3-ref) were synthesized similarly but in the absence of Dopa molecules in the initial sol-gel reaction. The appearance of characteristic D and G bands in the Raman spectra and distinct vibrational modes in the FTIR spectra of HT-MoO3/C confirmed the presence of carbon in its structure. SEM images showed a uniform nanobelt morphology with fragmentation due to interactions between interlayer Dopa and MoO3 layers under the conditions of hydrothermal treatment. HT-MoO3/C delivered a second-cycle capacitance of 141.4 F/g when cycled at 2 mV/s in a -0.25–0.70 V versus Ag/AgCl potential window in 5M ZnCl2 electrolyte, while α-MoO3-ref delivered a nearly two-fold smaller second-cycle capacitance of 76.1 F/g under the same conditions. HT-MoO3/C also showed increased capacitance compared to α-MoO3-ref when cycled at increasing sweep rates up to 20 mV/s. The superior performance of HT-MoO3/C prompted a study of the electrode in an expanded potential window, based on previous reports in which MoO3 showed electrochemical activity at negative potentials versus Ag/AgCl. The HT-MoO3/C electrode exhibited a capacitance of 347.6 F/g on the second cycle when cycled between -0.85–1.00V versus Ag/AgCl at 2 mV/s in 5M ZnCl2 electrolyte. This work demonstrates a new strategy to improve the electrochemical performance of transition metal oxide electrodes for next-generation energy storage systems. Integration of oxides with carbon through the wet chemistry synthesis approaches that involve carbonization of organic molecules can be used to control oxide crystal phase and heterointerfaces leading to improved charge transfer and energy storage properties.
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Kang, Myoungsuk, e Jiwan Kim. "A Study on the ZnO Thin Film Deposited by RF Sputtering Method as an Electron Transport Layer in Quantum Dot Light-Emitting Diodes". Korean Journal of Metals and Materials 59, n. 10 (5 ottobre 2021): 718–23. http://dx.doi.org/10.3365/kjmm.2021.59.10.730.
Testo completoAbstract (sommario):
We report a highly efficient quantum dot light emitting diode (QLEDs) with a radio frequency (RF) sputtered ZnO thin film as an electron transport layer (ETL) instead of the conventional ZnO nanoparticles (NPs) by solution process. ZnO NPs have been used as a key material to improve the performance of QLEDs, but the charge imbalance in ZnO NPs resulting from fast electron injection, and their limited uniformity are significant disadvantages. In this study, ZnO layers were deposited by RF sputtering with various O2 partial pressures. All of the ZnO films showed preferential growth along the (002) direction, smooth morphology, and good optical transmittance. To test their feasibility for QLEDs, we fabricated devices with RF sputtered ZnO layers as an ETL, which has the inverted structure of ITO/RF sputtered ZnO/QDs/CBP/MoO3/Al. The optical/electrical characteristics of two devices, comprised of RF sputtered ZnO and ZnO NPs, were compared with each other. QLEDs with the sputtered ZnO ETL achieved a current efficiency of 11.32 cd/A, which was higher than the 8.23 cd/A of the QLEDs with ZnO NPs ETL. Next, to find the optimum ZnO thin film for highly efficient QLEDs, deposition conditions with various O2 partial pressures were tested, and device performance was investigated. The maximum current efficiency was 13.33 cd/A when the ratio of Ar/O2 was 4:3. Additional oxygen gas reduced the O vacancies in the ZnO thin film, which resulted in a decrease in electrical conductivity, thereby improving charge balance in the emission layer of the QLEDs. As a result, we provide a way to control the ZnO ETL properties and to improve device performance by controlling O2 partial pressure.
32
Kang, Myoungsuk, e Jiwan Kim. "A Study on the ZnO Thin Film Deposited by RF Sputtering Method as an Electron Transport Layer in Quantum Dot Light-Emitting Diodes". Korean Journal of Metals and Materials 59, n. 10 (5 ottobre 2021): 718–23. http://dx.doi.org/10.3365/kjmm.2021.59.10.718.
Testo completoAbstract (sommario):
We report a highly efficient quantum dot light emitting diode (QLEDs) with a radio frequency (RF) sputtered ZnO thin film as an electron transport layer (ETL) instead of the conventional ZnO nanoparticles (NPs) by solution process. ZnO NPs have been used as a key material to improve the performance of QLEDs, but the charge imbalance in ZnO NPs resulting from fast electron injection, and their limited uniformity are significant disadvantages. In this study, ZnO layers were deposited by RF sputtering with various O2 partial pressures. All of the ZnO films showed preferential growth along the (002) direction, smooth morphology, and good optical transmittance. To test their feasibility for QLEDs, we fabricated devices with RF sputtered ZnO layers as an ETL, which has the inverted structure of ITO/RF sputtered ZnO/QDs/CBP/MoO3/Al. The optical/electrical characteristics of two devices, comprised of RF sputtered ZnO and ZnO NPs, were compared with each other. QLEDs with the sputtered ZnO ETL achieved a current efficiency of 11.32 cd/A, which was higher than the 8.23 cd/A of the QLEDs with ZnO NPs ETL. Next, to find the optimum ZnO thin film for highly efficient QLEDs, deposition conditions with various O2 partial pressures were tested, and device performance was investigated. The maximum current efficiency was 13.33 cd/A when the ratio of Ar/O2 was 4:3. Additional oxygen gas reduced the O vacancies in the ZnO thin film, which resulted in a decrease in electrical conductivity, thereby improving charge balance in the emission layer of the QLEDs. As a result, we provide a way to control the ZnO ETL properties and to improve device performance by controlling O2 partial pressure.
33
Lee, Thomas (Yew Sing). "A Closed Form Solution for the Asymmetric Random Polling System with Correlated Levy Input Process". Mathematics of Operations Research 22, n. 2 (maggio 1997): 432–57. http://dx.doi.org/10.1287/moor.22.2.432.
Testo completo
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Shi, Jiayuan, Li Liu, Shusen Kang, Xiaotao Chen e Bin Shi. "Cathode materials with mixed phases of orthorhombic MoO3 and Li0.042MoO3 for lithium-ion batteries". Canadian Journal of Chemistry 98, n. 2 (febbraio 2020): 106–13. http://dx.doi.org/10.1139/cjc-2019-0382.
Testo completoAbstract (sommario):
MoO3 is a promising cathode candidate for lithium-ion batteries and its electronic conductivity is usually improved by MoO3lithiation via reaction of MoO3 with LiCl solutions. However, this process might increase the manufacturing complexity and result in surface breakage of MoO3 cathodes. In this paper, by introducing lithium source into MoO3 synthesis, MoO3 can be lithiated through introduction of the Li0.042MoO3 phase into the MoO3 structure. XRD and ICP results indicate that the phase composition and lithium content can be regulated by changing the amount of lithium source in the reaction solutions. FESEM and specific surface area measurements show that the particle size becomes more uniform and the surface area is increased when the degree of MoO3 lithiation is higher. The lithiated MoO3 sample shows better cycling performance than that of pristine MoO3, which is mainly due to the enhanced conductivity and increased surface area of the lithiated MoO3.
35
Lee, Dongwook, e Rémi Bourgeois. "GP-MOOD: a positivity-preserving high-order finite volume method for hyperbolic conservation laws". Proceedings of the International Astronomical Union 16, S362 (giugno 2020): 373–79. http://dx.doi.org/10.1017/s1743921322001363.
Testo completoAbstract (sommario):
AbstractWe present an a posteriori shock-capturing finite volume method algorithm called GP-MOOD. The method solves a compressible hyperbolic conservative system at high-order solution accuracy in multiple spatial dimensions. The core design principle in GP-MOOD is to combine two recent numerical methods, the polynomial-free spatial reconstruction methods of GP (Gaussian Process) and the a posteriori detection algorithms of MOOD (Multidimensional Optimal Order Detection). We focus on extending GP’s flexible variability of spatial accuracy to an a posteriori detection formalism based on the MOOD approach. The resulting GP-MOOD method is a positivity-preserving method that delivers its solutions at high-order accuracy, selectable among three accuracy choices, including third-order, fifth-order, and seventh-order.
36
Kamoun, Faouzi, May El Barachi, Russell Hamilton e Ahmed Ben Hadj Khelifa. "The IASO Self-Reporting System". International Journal of Applied Research on Public Health Management 5, n. 2 (luglio 2020): 40–62. http://dx.doi.org/10.4018/ijarphm.2020070104.
Testo completoAbstract (sommario):
Mood swings are commonly observed phenomena among hospitalized patients. As a result, there has been a growing interest in developing solutions that can assist caregivers in acquiring a better understanding of patient mood states and behaviors. A key challenge resides in the need to not only monitor patients' mood state but also to try to influence it and regulate it. This article presents the IASO self-reporting system, a persuasive clinical mood tracking, and a management application for hospital patients. We describe the design process of the system, its technical implementation details, and key features. Unlike most earlier related studies, IASO incorporates the concept of mood-based adaptive art (MBAA) that triggers animated digital art clips with background sounds in response to patients' self-reported mood states, thus offering a tool for creative healing and mood enhancement. Our proposed solution empowers patients to gain more control over their wellbeing, regulates their moods and enables caregivers to receive timely feedback about potential mood swings and dangerous mood conditions.
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Grebeniak, Andrii. "Cyber-physical System to Help Moor a Ship". Advances in Cyber-Physical Systems 5, n. 2 (3 ottobre 2020): 63–69. http://dx.doi.org/10.23939/acps2020.02.063.
Testo completoAbstract (sommario):
A method of organizing an information cyber- physical system to assist in the mooring process has been considered in the article. It describes ways to organize the mooring of ships to the berth. The problems that occur during this operation have been listed. As the mooring process is labor- intensive and depends on the human factor, a system that will provide up-to-date real-time information to facilitate the mooring operation has been regarded. The structure and stages of development of the proposed solution have been described. The features of the selected elements have been indicated. Obtaining preliminary sensory results from two ports makes it possible to begin the next stage of system development.
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Beloglazov, Alexander A., Lilia B. Beloglazova, Igor M. Malkov, Natalia A. Antonova, Liliya A. Alekseeva, Polina A. Kopylova, Natalia V. Novoselova, Sofya D. Pudovkina e Irina A. Beloglazova. "Possibilities of telecommunicational training and information system and MOOC in comprehensive solution of tasks of teaching foreign students in Russian universities". RUDN Journal of Informatization in Education 17, n. 1 (15 dicembre 2020): 26–35. http://dx.doi.org/10.22363/2312-8631-2020-17-1-26-35.
Testo completoAbstract (sommario):
Problem and goal. The article actualizes the problem of integrating the capabilities of a massive open online course (MOOC) and a telecommunicational training and information system (TUIS) of the university, taking into account the identification of opportunities for this integration for a comprehensive solution of the problems of teaching foreign students at the university. Methodology. One of the most effective solutions in the framework of the considered prospects for the development of a modern university is the integration of MOOC and TUIS systems. Results. The possibilities of innovative forms of distance education for the organization of the educational process in the university are revealed. The perspective possibilities of integration of the MOOC and the telecommunication educational and information system within the functioning of the modern digital educational environment of the university are identified and disclosed. Conclusion. The integration of MOOC and TUIS systems allows to neutralize the nuances associated with the orientation of MOOC to a large number of users. Despite the fact that the number of university students is high, taking into account the characteristics of a particular university is provided by the interaction of MOOC and TUIS systems, which makes the educational process progressive, innovative and focused on modern development trends.
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Popczyk, Magdalena, e B. Łosiewicz. "Effect of Molybdenum(IV) Oxide on the Process of Hydrogen Evolution on Ni+Mo Electrolytic Composite Coatings". Solid State Phenomena 228 (marzo 2015): 277–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.228.277.
Testo completoAbstract (sommario):
The Ni+Mo and Ni+MoO2+Mo composite coatings were electrodeposited at the constant deposition current density ofjdep= -200 mA cm-2from the nickel plating bath containing powder of Mo or MoO2and Mo. The investigations of hydrogen evolution reaction (HER) were carried out in 5 M KOH solution at room temperature using steady-state polarization and electrochemical impedance spectroscopy (EIS) techniques. It was found that for the Ni+MoO2+Mo composite coating the increase in the activity of HER was observed in comparison with Ni+Mo composite coating probably due to the more porous surface and presence of additional composite component (MoO2) in the nickel matrix.
40
Nikolichev, Ilya, e Vladimir Sesyukalov. "Design of a Low-Energy Earth-Moon Flight Trajectory Using a Planar Auxiliary Problem". Applied Sciences 13, n. 3 (2 febbraio 2023): 1967. http://dx.doi.org/10.3390/app13031967.
Testo completoAbstract (sommario):
The paper presents a sufficiently simple technique for designing a low-energy flight trajectory of a spacecraft (SC) from the Earth to the Moon with insertion into a low circular orbit of the latter. The proposed technique is based on the solution and subsequent analysis of a special model problem, which is a variant of the restricted circular four-body problem (RC4BP) Earth-Sun-SC-Moon; for which it is assumed that the planes of the orbits of all considered bodies coincides. The planar motion of the center of mass of the SC relative to the Earth is considered as perturbed (Sun, Moon). To describe it, equations in osculating elements are used, obtained by using the method of variation of constants based on the analytical solution of the planar circular restricted problem of two bodies (RC2BP)—Earth-SC, for which the rotation of the main axes of the coordinate system (the main plane) is synchronized with the motion of the Sun. The trajectory problem of designing a SC flight from a low circular near-Earth orbit to a low circular selenocentric one (“full” motion model—a restricted four-body problem (R4BP), an ephemeris model) is considered as an optimization one in the impulse formulation. The solution of the main problem is carried out in few (three) stages, on each the appropriate solution of the current variant of the auxiliary problem is determined, which is subsequently used as the basis of the initial approximation to the main one.
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Pratama, Aldi Adi, Hans Pangaribuan, I. Gede Yoga Widnyana, Sifa Hardiyati Fatikha, Warista Yessy Sakinah e Ratih Pratiwi. "MASTER-D W-MOOC PLATFORM BASED MEDIA AS AN ONLINE LEARNING SOLUTION FOR DYSLEXIC ACCOUNTING STUDENTS". Vol 14 No 1 (2022): April Edition 14, n. 1 (4 aprile 2022): 41–54. http://dx.doi.org/10.23969/jrak.v14i1.5094.
Testo completoAbstract (sommario):
Health protocol rules during the New Normal period due to the COVID-19 virus pandemic in Indonesia are serious obstacle, especially the online learning process in universities. Accounting students are required to excel in attending lectures and online practice, including accounting students with dyslexia. This study uses a qualitative descriptive method with naturalistic and interpretive paradigms that describe solutions for dyslexic students in adjusting to being able to complete their education and can be realized at the time of graduation. Subjects consisted of senior professional educators from Dyslexia Center Indonesia (DCI). The Open Online Course (W-MOOC) is needed for people with dyslexia as a learning solution to improve the innovation ability of applied accounting skills, and prepare graduates' competencies according to their field of study.
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Aghajani, Reza, e Kavita Ramanan. "The Limit of Stationary Distributions of Many-Server Queues in the Halfin–Whitt Regime". Mathematics of Operations Research 45, n. 3 (agosto 2020): 1016–55. http://dx.doi.org/10.1287/moor.2019.1021.
Testo completoAbstract (sommario):
We consider the so-called GI/GI/N queue, in which a stream of jobs with independent and identically distributed service times arrive as a renewal process to a common queue that is served by [Formula: see text] identical parallel servers in a first-come, first-served manner. We introduce a new representation for the state of the system and, under suitable conditions on the service and interarrival distributions, establish convergence of the corresponding sequence of centered and scaled stationary distributions in the so-called Halfin–Whitt asymptotic regime. In particular, this resolves an open question posed by Halfin and Whitt in 1981. We also characterize the limit as the stationary distribution of an infinite-dimensional, two-component Markov process that is the unique solution to a certain stochastic partial differential equation. Previous results were essentially restricted to exponential service distributions or service distributions with finite support, for which the corresponding limit process admits a reduced finite-dimensional Markovian representation. We develop a different approach to deal with the general case when the Markovian representation of the limit is truly infinite dimensional. This approach is more broadly applicable to a larger class of networks.
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Wannapop, Surangkana, Titipun Thongtem e Somchai Thongtem. "Characterization of Donut-Like SrMoO4Produced by Microwave-Hydrothermal Process". Journal of Nanomaterials 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/474576.
Testo completoAbstract (sommario):
SrMoO4hierarchical nanostructures were successfully produced by a one step of 270 W microwave-hydrothermal process of one of the solutions containing three strontium salts [Sr(NO3)2, Sr(CH3CO2)2, and SrCl2·6H2O] and (NH4)6Mo7O24·4H2O for different lengths of time. The as-produced products were characterized by X-ray diffraction, electron microscopy, and spectroscopy. In this research, they were primitive tetragonal structured donut-like SrMoO4, with the main 881cm−1 ν1(Ag)symmetric stretching vibration mode of[MoO4]2−units and 3.92 eV energy gap.
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Abed, Baraa Mohammed, e Wesam Mohammed Jasim. "Multi Objective Optimization Algorithms for Mobile Robot Path Planning: A Survey". International Journal of Online and Biomedical Engineering (iJOE) 18, n. 15 (6 dicembre 2022): 160–77. http://dx.doi.org/10.3991/ijoe.v18i15.34397.
Testo completoAbstract (sommario):
Path planning algorithms is the most significant area in the robotics field. Path Planning (PP) can be defined as the process of determining the most appropriate navigation path before a mobile robot moves. Optimization of path planning refers to finding the optimal or near-optimal path. Multi-objective optimization (MOO) is concerned with finding the best solution values that satisfy multiple objectives, such as shortness, smoothness, and safety. MOOs present the challenge of making decisions while balancing these contradictory issues through compromise (tradeoff). As a result, there is no single solution appropriate for all purposes in MOO, but rather a range of solutions. The purpose of this paper is to present an overview of mobile robot navigation strategies employed to find the path that has the minimum number of criteria (shortest, smoothness, and safest) so far. Here, multi objective approaches are discussed in detail in order to identify research gaps. In addition, it is important to understand how path planning strategies are developed under various environmental circumstances.
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El-Shobaky, G. A., e Kh A. Khalil. "Surface Characteristics of the Pure and Li2O-doped MoO3/Al2O3 System". Adsorption Science & Technology 16, n. 2 (marzo 1998): 127–34. http://dx.doi.org/10.1177/026361749801600206.
Testo completoAbstract (sommario):
Two series of MoO3/Al2O3 solids, having the nominal compositions 0.2MoO3: Al2O3 and 0.5MoO3:A12O3, were prepared by impregnating finely powdered Al(OH)3 samples with calculated amounts of ammonium molybdate solutions. The solids thus obtained were dried at 120°C and then calcined in air at temperatures varying between 400°C and 1000°C. The doped samples were prepared by treating Al(OH)3 with LiNO3 solutions prior to impregnation with ammonium molybdate. The dopant concentrations employed were 1.5 and 6.0 mol% Li2O, respectively. The surface characteristics, viz. the specific surface area (SBET), the total pore volume (VP) and the mean pore radius (r) of the various pure and doped solids were measured from nitrogen adsorption isotherms conducted at -196°C. The SBET data measured for different adsorbents calcined at various temperatures enabled the apparent activation energy for sintering (ΔE3) to be determined for all the adsorbents investigated. The results obtained reveal that the SBET value of the pure and doped solids decreased on increasing the calcination temperature in the range 400–1000°C. The decrease was, however, more pronounced when the calcination temperature increased from 500°C to 700°C due to the formation of Al2(MoO4)3. Lithium oxide doping decreased the SBET value of the solid samples investigated and also decreased the activation energy for sintering to an extent proportional to the amount of dopant present. The sintering process for the pure and doped solids proceeds, mainly, via a particle adhesion mechanism.
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Zhu, Wen, e Jingwei Chen. "Two-dimensional photocatalyst with highly efficient and stable visible light photocatalytic activity". Advances in Engineering Technology Research 1, n. 2 (24 settembre 2022): 457. http://dx.doi.org/10.56028/aetr.1.2.457.
Testo completoAbstract (sommario):
Hex ammonium molybdate (AHM), ammonium nitrate (NH4NO3), and glycine were used as the precursors in a microwave-assisted solution combustion synthesis (WSCS) process to create foam-like MoO2 nanoparticles. Methodically investigated was the effect of the glycine/NH4NO3 ratio (=0.25, 0.50, 0.75, 1.0 and 1.25) on the finished goods. The findings indicate that the final morphologies and phases of the products are virtually influenced by the value of Φ. MoO2 nanoparticles measuring 20 to 30 nm can be successfully composited under the condition of Φ=0.50 to produce a foam-like result. The photocatalytic activity of foam-like MoO2 nanoparticles was tested with several pollutants. The results show that foam-like MoO2 nanoparticles have good degradability and stability. The photocatalytic mechanism and fabrication mechanism of foam-like MoO2 has been presented in detail. Using foam-like MoO2-based photocatalyst materials for energy transfer and environment protection is supported by this research.
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Zhu, Wen, e Jingwei Chen. "Two-dimensional photocatalyst with highly efficient and stable visible light photocatalytic activity". Advances in Engineering Technology Research 2, n. 1 (24 settembre 2022): 457. http://dx.doi.org/10.56028/aetr.2.1.457.
Testo completoAbstract (sommario):
Hex ammonium molybdate (AHM), ammonium nitrate (NH4NO3), and glycine were used as the precursors in a microwave-assisted solution combustion synthesis (WSCS) process to create foam-like MoO2 nanoparticles. Methodically investigated was the effect of the glycine/NH4NO3 ratio (=0.25, 0.50, 0.75, 1.0 and 1.25) on the finished goods. The findings indicate that the final morphologies and phases of the products are virtually influenced by the value of Φ. MoO2 nanoparticles measuring 20 to 30 nm can be successfully composited under the condition of Φ=0.50 to produce a foam-like result. The photocatalytic activity of foam-like MoO2 nanoparticles was tested with several pollutants. The results show that foam-like MoO2 nanoparticles have good degradability and stability. The photocatalytic mechanism and fabrication mechanism of foam-like MoO2 has been presented in detail. Using foam-like MoO2-based photocatalyst materials for energy transfer and environment protection is supported by this research.
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Tuktin B.T.,, Shapovalova L.B.,, Tenizbayeva A.A.,, Abilmagzhanov A.Z., e Egizbaeva R.I.,. "HYDROTREATING AND HYDROISOMERIZATION OF OIL FRACTIONS ON MODIFIED ALUMINUM-COBALTMOLYBDENUM CATALYSTS". SERIES CHEMISTRY AND TECHNOLOGY 5, n. 443 (ottobre 2020): 99–107. http://dx.doi.org/10.32014/2020.2518-1491.86.
Testo completoAbstract (sommario):
In this work we are given results and research of hydro refining of gasoline and diesel oil fractions on alumina catalysts CoO-MoO3-La2О3-Р2О5-ZSM-Al2O3, CoO-MoO3-Ce2О3-Р2О5-ZSM-HY-Al2O3, CoO-MoO3-La2О3-Р2О5- AAC-ZSM -Al2O3. The catalysts were prepared by impregnating a mixture of aluminum hydroxide and zeolites ZSM-5, HY with aqueous solutions of salts Co, Mo, La and phosphoric acid. Large-scale laboratory tests of the synthesized catalysts were carried out in the process of hydro processing of various types of gasoline and diesel fractions. At hydro treating of straight-run gasoline over CoO-MoO3-La2О3-Р2О5-ZSM-Al2O3 shows that in the temperature range 320 - 350оС the maximum amount of isoalkanes is formed 33.4-40.4%. The octane number of refined gasoline increases in comparison with the initial one from 78.9 to 89.3 (RON) and from 60.9 to 73.4 (MON). The sulfur content of catalysate with increasing temperature up to 400оС decreased to 0.0012 %. At hydro processing of catalytic cracking gasoline on CoO-MoO3-La2О3-Р2О5-ZSM-Al2O3 the octane number of refined gasoline is slightly reduced. The sulfur content of catalysate with increasing temperature up to 400оС decreased from initial with from 0.0134 to 0 0014 %. It was found that the lowest pour point and cloud point of hydro-refined diesel fuel is observed on the catalyst CoO-MoO3-La2O3-P2O5-ZSM-Al2O3. After hydro treating on this catalyst the pour point and cloud point are equal to minus 52.7oC and minus 40.8oC accordingly. This same catalyst has the highest hydro desulfurization activity: the sulfur content decreases from 0.5600% to 0.104%. Thus, the developed modified zeolite-containing catalysts CoO-MoO3-La2О3-P2O5-ZSM-Al2O3, CoO-MoO3-Се2О3-P2O5-ZSM-HY-Al2O3, CoO-MoO3-La2О3-P2O5-AAC-ZSM-Al2O3, exhibiting high activity at hydro treating of gasoline and diesel fractions and is able in one stage deep hydro treating, hydro isomerization and hydrocracking which allows to obtain low-sulfur, high-octane gasoline and low-sulfur and low solidifying diesel fuel which is important for operation of vehicles in winter conditions.
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Bo, Lijun, Agostino Capponi e Chao Zhou. "Power Forward Performance in Semimartingale Markets with Stochastic Integrated Factors". Mathematics of Operations Research 48, n. 1 (febbraio 2023): 288–312. http://dx.doi.org/10.1287/moor.2022.1262.
Testo completoAbstract (sommario):
We study the forward investment performance process (FIPP) in an incomplete semimartingale market model with closed and convex portfolio constraints, when the investor’s risk preferences are of the power form. We provide necessary and sufficient conditions for the existence of such a FIPP. In a semimartingale factor model, we show that the FIPP can be recovered as a triplet of processes that admit an integral representation with respect to semimartingales. Using an integrated stochastic factor model, we relate the factor representation of the triplet of processes to the smooth solution of an ill-posed partial integro-differential Hamilton–Jacobi–Bellman equation. We develop explicit constructions for the class of time-monotone FIPPs, generalizing existing results from Brownian to semimartingale market models. Funding: L. Bo was supported by the National Natural Science Foundation of China (NSFC) [Grant 11971368] and National Center for Applied Mathematics in Shaanxi (NCAMS). A. Capponi was supported in part by the National Science Foundation [Grant DMS-1716145]. C. Zhou was supported by the Singapore Ministry of Education Academic Research Fund [Grant R-146-000-271-112] and NSFC [Grant 11871364].
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Gu, Siyong, Mingli Qin, Houan Zhang e Jidong Ma. "Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen". Materials 11, n. 12 (27 novembre 2018): 2385. http://dx.doi.org/10.3390/ma11122385.
Testo completoAbstract (sommario):
This work reports the preparation of La2O3 uniformly doped Mo nanopowders with the particle sizes of 40–70 nm by solution combustion synthesis and subsequent hydrogen reduction (SCSHR). To reach this aim, the foam-like MoO2 precursors (20–40 nm in size) with different amounts of La2O3 were first synthesized by a solution combustion synthesis method. Next, these precursors were used to prepare La2O3 doped Mo nanopowders through hydrogen reduction. Thus, the content of La2O3 used for doping can be accurately controlled via the SCSHR route to obtain the desired loading degree. The successful doping of La2O3 into Mo nanopowders with uniform distribution were proved by X-ray photon spectroscopy and transmission electron microscopy. The preservation of the original morphology and size of the MoO2 precursor by the La2O3 doped Mo nanopowders was attributed to the pseudomorphic transport mechanism occurring at 600 °C. As shown by X-ray diffraction, the formation of Mo2C impurity, which usually occurs in the direct H2 reduction process, can be avoided by using the Ar calcination-H2 reduction process, when residual carbon is removed by the carbothermal reaction during Ar calcination at 500 °C.