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Articles de revues sur le sujet « Methanol-water »

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Auteur : Grafiati
Publié le 18 mai 2024

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1

Fileti, Eudes E., et Sylvio Canuto. « Calculated infrared spectra of hydrogen-bonded methanol-water, water-methanol, and methanol-methanol complexes ». International Journal of Quantum Chemistry 104, no 5 (2005) : 808–15. http://dx.doi.org/10.1002/qua.20585.

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2

Barraclough, Colin G., Peter T. McTigue et Y. Leung Ng. « Surface potentials of water, methanol and water + methanol mixtures ». Journal of Electroanalytical Chemistry 329, no 1-2 (juillet 1992) : 9–24. http://dx.doi.org/10.1016/0022-0728(92)80205-i.

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3

Kurihara, Kiyofumi, Tsuyoshi Minoura, Kouichi Takeda et Kazuo Kojima. « Isothermal Vapor-Liquid Equilibria for Methanol + Ethanol + Water, Methanol + Water, and Ethanol + Water ». Journal of Chemical & ; Engineering Data 40, no 3 (mai 1995) : 679–84. http://dx.doi.org/10.1021/je00019a033.

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4

Masella, Michel, et Jean Pierre Flament. « Relation between cooperative effects in cyclic water, methanol/water, and methanol trimers and hydrogen bonds in methanol/water, ethanol/water, and dimethylether/water heterodimers ». Journal of Chemical Physics 108, no 17 (mai 1998) : 7141–51. http://dx.doi.org/10.1063/1.476131.

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5

Ratanakandilok, S. « Coal desulfurization with methanol/water and methanol/KOH ». Fuel and Energy Abstracts 43, no 4 (juillet 2002) : 236. http://dx.doi.org/10.1016/s0140-6701(02)86071-4.

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6

Ratanakandilok, S., S. Ngamprasertsith et P. Prasassarakich. « Coal desulfurization with methanol/water and methanol/KOH ». Fuel 80, no 13 (octobre 2001) : 1937–42. http://dx.doi.org/10.1016/s0016-2361(01)00047-3.

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7

Rived, Fernando, Immaculada Canals, Elisabeth Bosch et Martı́ Rosés. « Acidity in methanol–water ». Analytica Chimica Acta 439, no 2 (juillet 2001) : 315–33. http://dx.doi.org/10.1016/s0003-2670(01)01046-7.

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8

Sun, Tong, Gerald Wilemski, Barbara N. Hale et Barbara E. Wyslouzil. « The effects of methanol clustering on methanol–water nucleation ». Journal of Chemical Physics 157, no 18 (14 novembre 2022) : 184301. http://dx.doi.org/10.1063/5.0120876.

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The formation of subcritical methanol clusters in the vapor phase is known to complicate the analysis of nucleation measurements. Here, we investigate how this process affects the onset of binary nucleation as dilute water–methanol mixtures in nitrogen carrier gas expand in a supersonic nozzle. These are the first reported data for water–methanol nucleation in an expansion device. We start by extending an older monomer–dimer–tetramer equilibrium model to include larger clusters, relying on Helmholtz free energy differences derived from Monte Carlo simulations. The model is validated against the pressure/temperature measurements of Laksmono et al. [Phys. Chem. Chem. Phys. 13, 5855 (2011)] for dilute methanol–nitrogen mixtures expanding in a supersonic flow prior to the appearance of liquid droplets. These data are well fit when the maximum cluster size imax is 6–12. The extended equilibrium model is then used to analyze the current data. On the addition of small amounts of water, heat release prior to particle formation is essentially unchanged from that for pure methanol, but liquid formation proceeds at much higher temperatures. Once water comprises more than ∼24 mol % of the condensable vapor, droplet formation begins at temperatures too high for heat release from subcritical cluster formation to perturb the flow. Comparing the experimental results to binary nucleation theory is challenged by the need to extrapolate data to the subcooled region and by the inapplicability of explicit cluster models that require a minimum of 12 molecules in the critical cluster.
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9

Tian, Gang, Cong Yang, Xiaoxia Li, Guoxu He, Xiaojun Zhao, Xiaoming Peng, Cuiqing Li, Liang Chen et Binbin Zhang. « Determination and correlation of refractive index of three binary and ternary systems containing hydroxyl ionic liquids/ water/methanol ». Materials Express 10, no 4 (1 avril 2020) : 469–78. http://dx.doi.org/10.1166/mex.2020.1667.

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In this paper, the refractive index of methanol + water, [HOEMIm]Cl + methanol, [HOEMMIm]Cl + methanol, [OHEN1,1,1]Cl + methanol, [HOEMIm]Cl + water, [OHEN1,1,1]Cl + water, [HOEMMIm]Cl + water, [OHEN1,1]Cl + water, [HOEMIm]Cl + methanol + water, [HOEMMIm]Cl + methanol + water and [OHEN1,1,1]Cl+methanol+water at different temperatures were determined by refractometer. The physical database of hydroxyl ionic liquids was enriched, and the excess refractive index of these systems was obtained by calculation. The relationship between the refractive index or the excess refractive index and the composition mole fraction were established at 20 °C.
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10

Buettner, Joerg, Maritza Gutierrez et A. Henglein. « Sonolysis of water-methanol mixtures ». Journal of Physical Chemistry 95, no 4 (février 1991) : 1528–30. http://dx.doi.org/10.1021/j100157a004.

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11

Boukis, N., V. Diem, W. Habicht et E. Dinjus. « Methanol Reforming in Supercritical Water ». Industrial & ; Engineering Chemistry Research 42, no 4 (février 2003) : 728–35. http://dx.doi.org/10.1021/ie020557i.

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12

Kooi, J. « The system methylmethacrylate - methanol - water ». Recueil des Travaux Chimiques des Pays-Bas 68, no 1 (2 septembre 2010) : 34–42. http://dx.doi.org/10.1002/recl.19490680103.

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13

Vaidya, Pravin S., et Raghavendra V. Naik. « Liquid−Liquid Equilibria for the Epichlorohydrin + Water + Methanol and Allyl Chloride + Water + Methanol Systems ». Journal of Chemical & ; Engineering Data 48, no 4 (juillet 2003) : 1015–18. http://dx.doi.org/10.1021/je034018b.

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14

Wang, C. H., K. L. Pan, G. J. Ueng, L. J. Kung et J. Y. Yang. « Burning behaviors of collision-merged water/diesel, methanol/diesel, and water+methanol/diesel droplets ». Fuel 106 (avril 2013) : 204–11. http://dx.doi.org/10.1016/j.fuel.2012.12.022.

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15

Vašková, Hana, et Martin Tomeček. « Rapid spectroscopic measurement of methanol in water-ethanol-methanol mixtures ». MATEC Web of Conferences 210 (2018) : 02035. http://dx.doi.org/10.1051/matecconf/201821002035.

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The paper is focused on the Raman spectroscopic analysis of methanol content in water-ethanol-methanol mixtures as this kind of mixture chemically closely relates to alcoholic drinks. Counterfeit alcoholic drinks represent losses to the economy, but especially can cause serious health risks starting from nausea, to blindness, and even death. Extensive methanol poisonings were reported in last decades in number of countries worldwide. A set of water-ethanol-methanol mixtures with a range of concentrations of methanol from 0 % to 100 % was prepared to obtain the calibration dataset, needful for quantitative assessment. Based on calibration data, test samples and alcoholic beverages were evaluated. Raman spectroscopy is used especially because of this method’s benefits as specific vibrational fingerprint, direct measurement through the bottles, no need of additional chemicals and fast response. The study confirms the rapid and accurate analysis complying with safety limits set by methanol spirits legislation.
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16

Isdale, J. D., A. J. Easteal et L. A. Woolf. « Shear viscosity of methanol and methanol + water mixtures under pressure ». International Journal of Thermophysics 6, no 5 (septembre 1985) : 439–50. http://dx.doi.org/10.1007/bf00508889.

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17

Alfenaar, M., et C. L. de Ligny. « The universal pH-scale in methanol and methanol-water mixtures ». Recueil des Travaux Chimiques des Pays-Bas 86, no 11 (2 septembre 2010) : 1185–90. http://dx.doi.org/10.1002/recl.19670861104.

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18

Noskov, S. Y., M. G. Kiselev, A. M. Kolker et B. M. Rode. « Structure of methanol-methanol associates in dilute methanol-water mixtures from molecular dynamics simulation ». Journal of Molecular Liquids 91, no 1-3 (avril 2001) : 157–65. http://dx.doi.org/10.1016/s0167-7322(01)00157-x.

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19

Zhai, Yanqin, Peng Luo, Jackson Waller, Jeffrey L. Self, Leland W. Harriger, Y. Z et Antonio Faraone. « Dynamics of molecular associates in methanol/water mixtures ». Physical Chemistry Chemical Physics 24, no 4 (2022) : 2287–99. http://dx.doi.org/10.1039/d1cp04726d.

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The nanoscopic mutual diffusion coefficient, DMn, of a methanol/water mixture is smaller than the single particle diffusion coefficient of either methanol or water, indicating the existence of dynamic associates of water and methanol molecules.
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20

Xu, Changchun, et Haengmuk Cho. « Effect of Methanol/Water Mixed Fuel Compound Injection on Engine Combustion and Emissions ». Energies 14, no 15 (25 juillet 2021) : 4491. http://dx.doi.org/10.3390/en14154491.

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Due to the recent global increase in fuel prices, to reduce emissions from ground transportation and improve urban air quality, it is necessary to improve fuel efficiency and reduce emissions. Water, methanol, and a mixture of the two were added at the pre-intercooler position to keep the same charge and cooling of the original rich mixture, reduce BSFC and increase ITE, and promote combustion. The methanol/water mixing volume ratios of different fuel injection strategies were compared to find the best balance between fuel consumption, performance, and emission trends. By simulating the combustion mechanism of methanol, water, and diesel mixed through the Chemkin system, the ignition delay, temperature change, and the generation rate of the hydroxyl group (−OH) in the reaction process were analyzed. Furthermore, the performance and emission of the engine were analyzed in combination with the actual experiment process. This paper studied the application of different concentration ratios of the water–methanol–diesel mixture in engines. Five concentration ratios of water–methanol blending were injected into the engine at different injection ratios at the pre-intercooler position, such as 100% methanol, 90% methanol/10% water, 60% methanol/40% water, 30% methanol/70% water, 100% water was used. With different volume ratios of premixes, the combustion rate and combustion efficiency were affected by droplet extinguishment, flashing, or explosion, resulting in changes in combustion temperature and affecting engine performance and emissions. In this article, the injection carryout at the pre-intercooler position of the intake port indicated thermal efficiency increase and a brake specific fuel consumption rate decrease with the increase of water–methanol concentration, and reduce CO, UHC, and nitrogen oxide emissions. In particular, when 60% methanol and 40% water were added, it was found that the ignition delay was the shortest and the cylinder pressure was the largest, but the heat release rate was indeed the lowest.
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21

Cassone, Giuseppe, Adriano Sofia, Jiri Sponer, A. Marco Saitta et Franz Saija. « Ab Initio Molecular Dynamics Study of Methanol-Water Mixtures under External Electric Fields ». Molecules 25, no 15 (24 juillet 2020) : 3371. http://dx.doi.org/10.3390/molecules25153371.

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Intense electric fields applied on H-bonded systems are able to induce molecular dissociations, proton transfers, and complex chemical reactions. Nevertheless, the effects induced in heterogeneous molecular systems such as methanol-water mixtures are still elusive. Here we report on a series of state-of-the-art ab initio molecular dynamics simulations of liquid methanol-water mixtures at different molar ratios exposed to static electric fields. If, on the one hand, the presence of water increases the proton conductivity of methanol-water mixtures, on the other, it hinders the typical enhancement of the chemical reactivity induced by electric fields. In particular, a sudden increase of the protonic conductivity is recorded when the amount of water exceeds that of methanol in the mixtures, suggesting that important structural changes of the H-bond network occur. By contrast, the field-induced multifaceted chemistry leading to the synthesis of e.g., hydrogen, dimethyl ether, formaldehyde, and methane observed in neat methanol, in 75:25, and equimolar methanol-water mixtures, completely disappears in samples containing an excess of water and in pure water. The presence of water strongly inhibits the chemical reactivity of methanol.
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22

Kostko, Oleg, Leonid Belau, Kevin R. Wilson et Musahid Ahmed. « Vacuum-Ultraviolet (VUV) Photoionization of Small Methanol and Methanol−Water Clusters† ». Journal of Physical Chemistry A 112, no 39 (2 octobre 2008) : 9555–62. http://dx.doi.org/10.1021/jp8020479.

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23

You, Shujie, Junchun Yu, Bertil Sundqvist, L. A. Belyaeva, Natalya V. Avramenko, Mikhail V. Korobov et Alexandr V. Talyzin. « Selective Intercalation of Graphite Oxide by Methanol in Water/Methanol Mixtures ». Journal of Physical Chemistry C 117, no 4 (18 janvier 2013) : 1963–68. http://dx.doi.org/10.1021/jp312756w.

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24

Yang, Wenshao, Zhenhua Geng, Qing Guo, Dongxu Dai et Xueming Yang. « Effect of Multilayer Methanol and Water in Methanol Photochemistry on TiO2 ». Journal of Physical Chemistry C 121, no 32 (3 août 2017) : 17244–50. http://dx.doi.org/10.1021/acs.jpcc.7b04224.

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25

VIJAYALAKSHMI, S., C. P. VINOD et G. U. KULKARNI. « A METHANOL–WATER COMPLEX STABILIZED ON A Zn(0001) SURFACE ». Surface Review and Letters 10, no 01 (février 2003) : 87–94. http://dx.doi.org/10.1142/s0218625x0300469x.

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Coadsorption of water and methanol on a clean Zn(0001) surface has been investigated by employing X-ray photoelectron spectroscopy after exposing the surface at 80 K to the binary vapor from water–methanol liquid mixtures of varying compositions and subsequently warming the surface up to the room temperature. When the surface was exposed to the vapor from a mixture with water molefraction, xw, of 0.5, the proton abstraction and the C–O bond cleavage in methanol leading to methoxy (CH3O) and the hydrocarbon ( CH x) species respectively, occurs at a much higher temperature of 180 K, compared to 120 K in the case of pure methanol adsorption. For water-rich mixtures (xw = 0.7 and 0.9) molecular methanol is stabilized on the surface up to 200 K, beyond which water itself desorbs. For xw = 0.7, virtually no dissociation is observed up to 200 K. The increased stability of molecular methanol on the Zn(0001) surface is attributed to the surface-mediated hydrogen bonds that stabilize a water–methanol complex.
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26

Pálinkás, G., et I. Bakó. « Excess Properties of Water-Methanol Mixtures as Studied by MD Simulations ». Zeitschrift für Naturforschung A 46, no 1-2 (1 février 1991) : 95–99. http://dx.doi.org/10.1515/zna-1991-1-215.

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AbstractMolecular dynamics simulations with pair interactions reproduce experimental excess properties of methanol-water mixtures. Water molecules lose, and methanol molecules gain neighbours in the mixtures as compared to the solvents. The water-methanol mixture with 0.25 mole fraction of methanol, resulting in extreme values for different excess properties, is characterized by the highest number of molecules with maximal number of H-bonded neighbours.
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27

Freakley, Simon J., Nikolaos Dimitratos, David J. Willock, Stuart H. Taylor, Christopher J. Kiely et Graham J. Hutchings. « Methane Oxidation to Methanol in Water ». Accounts of Chemical Research 54, no 11 (19 mai 2021) : 2614–23. http://dx.doi.org/10.1021/acs.accounts.1c00129.

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28

Bo, ZHENG, LI He-Xian, WANG Guo-Chang, LIU Kun, YUAN Wei, LI He et LIANG Bo. « Supramolecular Complexation in Water-Methanol Mixtures ». Acta Physico-Chimica Sinica 24, no 08 (2008) : 1503–6. http://dx.doi.org/10.3866/pku.whxb20080830.

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Mallamace, Francesco, Carmelo Corsaro, Domenico Mallamace, Cirino Vasi, Sebastiano Vasi et H. Eugene Stanley. « Dynamical properties of water-methanol solutions ». Journal of Chemical Physics 144, no 6 (14 février 2016) : 064506. http://dx.doi.org/10.1063/1.4941414.

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30

Szuromi, Phil. « A water boost for methanol synthesis ». Science 368, no 6490 (30 avril 2020) : 484.5–485. http://dx.doi.org/10.1126/science.368.6490.484-e.

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31

Endo, Harumi, Kenji Saijou et Gordon Atkinson. « Sound absorption in water-methanol mixtures. » Journal of the Acoustical Society of Japan (E) 13, no 2 (1992) : 85–90. http://dx.doi.org/10.1250/ast.13.85.

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32

Yan, Hong-Lei, Zhi-Min Zong, Wei-Wei Zhu, Zhan-Ku Li, Yu-Gao Wang, Zhe-Hao Wei, Yan Li et Xian-Yong Wei. « Poplar Liquefaction in Water/Methanol Cosolvents ». Energy & ; Fuels 29, no 5 (16 avril 2015) : 3104–10. http://dx.doi.org/10.1021/ef502518n.

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33

Flörke, Ulrich, Wahyudi Priyono Suwarso, Ratna Layla Gani, Karsten Krohn et Si Wang. « Dasypogalactone–methanol–water (1/2/1) ». Acta Crystallographica Section E Structure Reports Online 59, no 5 (16 avril 2003) : o638—o640. http://dx.doi.org/10.1107/s1600536803008055.

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34

Xu, Bei-Bei, Min Zhou, Ran Zhang, Man Ye, Ling-Yun Yang, Rong Huang, Hai Feng Wang, Xue Lu Wang et Ye-Feng Yao. « Solvent Water Controls Photocatalytic Methanol Reforming ». Journal of Physical Chemistry Letters 11, no 9 (21 avril 2020) : 3738–44. http://dx.doi.org/10.1021/acs.jpclett.0c00972.

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35

Savage, Phillip E., Ruokang Li et John T. Santini. « Methane to methanol in supercritical water ». Journal of Supercritical Fluids 7, no 2 (juin 1994) : 135–44. http://dx.doi.org/10.1016/0896-8446(94)90050-7.

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36

Barylka, A. G., et R. M. Balabai. « Graphene Wetting by Methanol or Water ». Ukrainian Journal of Physics 60, no 10 (octobre 2015) : 1049–54. http://dx.doi.org/10.15407/ujpe60.10.1049.

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37

Green, Gary J., et Tsoung Y. Yan. « Water tolerance of gasoline-methanol blends ». Industrial & ; Engineering Chemistry Research 29, no 8 (août 1990) : 1630–35. http://dx.doi.org/10.1021/ie00104a009.

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38

Pestov, Dmitry, Miaochan Zhi, Zoe-Elizabeth Sariyanni, Nikolai G. Kalugin, Alexander Kolomenskii, Robert Murawski, Yuri V. Rostovtsev, Vladimir A. Sautenkov, Alexei V. Sokolov et Marlan O. Scully. « Femtosecond CARS of methanol-water mixtures ». Journal of Raman Spectroscopy 37, no 1-3 (janvier 2006) : 392–96. http://dx.doi.org/10.1002/jrs.1482.

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39

Rao, R. Jagannadha, et C. Venkata Rao. « Ternary liquid equilibria : Methanol-water-esters ». Journal of Applied Chemistry 7, no 8 (4 mai 2007) : 435–39. http://dx.doi.org/10.1002/jctb.5010070804.

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40

Stouten, Pieter F. W., et J. Kroon. « Computation Confirms Contraction : A Molecular Dynamics Study of Liquid Methanol, Water and a Methanol-Water Mixture ». Molecular Simulation 5, no 3-4 (septembre 1990) : 175–79. http://dx.doi.org/10.1080/08927029008022129.

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41

Taghavi, Toktam, Hiral Patel, Omololu E. Akande et Dominique Clark A. Galam. « Total Anthocyanin Content of Strawberry and the Profile Changes by Extraction Methods and Sample Processing ». Foods 11, no 8 (7 avril 2022) : 1072. http://dx.doi.org/10.3390/foods11081072.

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Anthocyanins are the primarily pigments in many flowers, vegetables, and fruits and play a critical role in human and plant health. They are polyphenolic pigments that are soluble in water and usually quantified by spectrophotometric methods. The two main methods that quantify anthocyanins are pH differential and organic solvent-based methods. Our hypothesis was that these methods extract different anthocyanin profiles. Therefore, this experiment was designed to identify anthocyanin profiles that are extracted by pH differential and organic solvent-based methods and observe their total anthocyanin content from strawberries. Six methods were tested in this experiment to quantify and profile anthocyanins in strawberry fruits by spectrophotometry and Ultra High Performance Liquid Chromatography (UHPLC) respectively. Four methods used organic solvents (methanol, and chloroform-methanol) in different combinations. The next two methods were pH differential and a combination of organic solvent and the pH differential method. The results suggest that acidified chloroform-methanol extracted the highest anthocyanin content compared to water-based solvents. Methanol-water based solvents also performed better than methanol alone, because both methanol and water may extract different profiles of anthocyanins. Water-based extracts had the greatest absorbance at a lower wavelength (498 nm), followed by methanol (508 nm), and chloroform (530 nm). Chloroform-methanol solvent with higher pH (3.0) extracted pelargonidin as the main anthocyanin, while methanol and water-based solvents (with lower pH 1.0–2.0) extracted delphinidin as their main anthocyanin as identified by UHPLC. Therefore, chloroform-methanol and methanol-water solvents were the best solvents for extracting anthocyanins from strawberries. Also, freeze-dried strawberries had higher anthocyanin contents compared to fresh or frozen samples.
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42

Schick, Bernhard, Pran N. Moza, Klaus Hustert et Antonius Kettrup. « Photochemistry of vinclozolin in water and methanol-water solution ». Pesticide Science 55, no 11 (15 octobre 1999) : 1116–22. http://dx.doi.org/10.1002/(sici)1096-9063(199911)55:11<1116 ::aid-ps65>3.0.co;2-y.

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43

Haniš, Tomáš, Miroslav Smrž, Pavel Klír, Karel Macek et Zdeněk Deyl. « Improved separation of C12-C22 fatty acid phenacyl esters by reversed phase column liquid chromatography ». Collection of Czechoslovak Chemical Communications 51, no 12 (1986) : 2722–26. http://dx.doi.org/10.1135/cccc19862722.

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Phenacyl esters of C12-C22 fatty acids were separated on Separon SGX C18 column, using a gradient elution with methanol-acetonitrile-water. The proposed gradient showed better resolution of the critical pairs C18:3-C14:0, C16:1-C20:4, and C16:0-C18:1 than the gradient elution with methanol-water or acetonitrile-water, or than the isocratic elution with methanol-acetonitrile-water. The optimum volume concentration (83%) of the sum of both methanol and acetonitrile was maintained constant for 35 min; in this period the acetonitrile concentration decreased linearly from the initial 42-60% to 0% while the methanol concentration increased from the initial 41-23% to 83% at the same rate. After 35 min the elution was completed with a methanol-water gradient. The whole analysis can be performed within 63 min at a flow rate 1 ml/min.
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44

Takamuku, Toshiyuki, Toshio Yamaguchia, Masaki Asato, Masaki Matsumoto et Nobuyuki Nishi. « Structure of Clusters in Methanol-Water Binary Solutions Studied by Mass Spectrometry and X-ray Diffraction ». Zeitschrift für Naturforschung A 55, no 5 (1 mai 2000) : 513–25. http://dx.doi.org/10.1515/zna-2000-0507.

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Abstract The structure of clusters in methanol-water solutions in its dependence on the methanol mole fraction xM has been investigated by mass spectrometry on clusters isolated from submicron droplets by adiabatic expansion in vacuum and by X-ray diffraction on the bulk binary solutions. The mass spectra have shown that the average hydration number, (nm), of m-mer methanol clusters decreases with increasing xM , accompanied by two inflection points at xM = ~0.3 and ~0.7. The X-ray diffraction data have revealed a similar change in the number of hydrogen bonds per water and/or methanol oxygen atom at ~2.8 Å. On the basis of both results, most likely models of clusters formed in the binary solutions are proposed: at 0 < xM < 0.3 the tetrahedral-like water cluster is the main species, at 0.3 < xM < 0.7 chain clusters of methanol molecules gradually evolve with increasing methanol content, and finally, at xM > 7 chain clusters of methanol become predominant. The present results are compared with clusters previously found in ethanol-water binary solutions and discussed in relation to anomalies of the heat of mixing of methanol-water binary solutions.
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45

AGUSTINA, EVA. « UJI AKTIVITAS SENYAWA ANTIOKSIDAN DARI EKSTRAK DAUN TIIN (Ficus Carica Linn) DENGAN PELARUT AIR, METANOL DAN CAMPURAN METANOL-AIR ». KLOROFIL : Jurnal Ilmu Biologi dan Terapan 1, no 1 (1 novembre 2017) : 38. http://dx.doi.org/10.30821/kfl:jibt.v1i1.1240.

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<p>Antioxidants can ward off free radicals in the body to resist oxidative damage caused by free radicals. The aim of this research is to know the influence of water solvent, methanol and methanol-water mixture to antioxidant activity. The extraction is done by maceration method. The extraction results in the phytochemical test and functional group analysis to determine the compounds contained in Pig leaf extract. Further testing of antioxidant activity with DPPH method. Pig leaf extract with methanol solvent has antioxidant activity with IC50 3,3005 μg / ml value, Pig leaf extract with water solvent has antioxidant activity 3,6976 μg / ml and Pig leaf extract with methanol solvent: water has antioxidant activity 13,6140 μg / ml. The IC50 &lt;50 μg / ml value indicates that the Pig leaf extract with some solvents has potent antioxidant potential. Pig leaf extract with methanol solvent has the best antioxidant activity with IC50 3,3005 μg / ml value because according to phytochemical test and functional group analysis that methanol solvent is able to extract more active compound such as flavonoid, Triterpenoid and Sterol, Alkaloid and Saponin followed by Pig leaf extract with water solvent and methanol mixture: water.</p>
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46

Pytela, Oldřich, Taťjana Nevěčná et Jaromír Kaválek. « Reactivity of proton and general acid with 1,3-bis-(4-methylphenyl)triazene in aqueous methanol ». Collection of Czechoslovak Chemical Communications 55, no 11 (1990) : 2701–6. http://dx.doi.org/10.1135/cccc19902701.

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The effect of concentration of benzoic acid and composition of the binary solvent water-methanol on the rate of decomposition of 1,3-bis(4-methylphenyl)triazene has been studied. It has been found that both general acid catalysis by undissociated benzoic acid and catalysis by the proton are significant. The rate constant kHA of general acid catalysis decreases monotonously with decreasing amount of water in the mixture due to preferred solvation of the activated complex as compared with the educts. The rate constant kH of the catalysis by proton in its dependence on methanol concentration exhibits a minimum for 80% (by wt.) of methanol in the mixture. This phenomenon is caused by formation of the conjugated acid from more basic methanol and proton with simultaneous solvation by water and methanol; the particle thus formed is a weaker acid as compared with the complexes existing in water or in methanol. The kH value is higher in methanol than in water due to preferred solvation of the educts as compared with that of the transition state.
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47

Marenco, Leonardo Fabio León, Luiza Pereira de Oliveira, Daniella Lopez Vale et Maiara Oliveira Salles. « Predicting Vodka Adulteration : A Combination of Electronic Tongue and Artificial Neural Networks ». Journal of The Electrochemical Society 168, no 11 (1 novembre 2021) : 117513. http://dx.doi.org/10.1149/1945-7111/ac393e.

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An artificial neural network was used to build models caple of predicting and quantifying vodka adulteration with methanol and/or tap water. A voltammetric electronic tongue based on gold and copper microelectrodes was used, and 310 analyses were performed. Vodkas were adulterated with tap water (5 to 50% (v/v)), methanol (1 to 13% (v/v)), and with a fixed addition of 5% methanol and tap water varying from 5 to 50% (v/v). The classification model showed 99.5% precision, and it correctly predicted the type of adulterant in all samples. Regarding the regression model, the root mean squared error was 3.464% and 0.535% for the water and methanol addition, respectively, and the prediction of the adulterant content presented an R2 0.9511 for methanol and 0.9831 for water adulteration.
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48

Feibert, E. B. G., S. R. James, K. A. Rykbost, A. R. Mitchell et C. C. Shock. « Potato Yield and Quality Not Changed by Foliar-applied Methanol ». HortScience 30, no 3 (juin 1995) : 494–95. http://dx.doi.org/10.21273/hortsci.30.3.494.

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Previously published research suggests that the yield and water-use efficiency of C-3 plants can be enhanced through foliar-applied methanol. Potatoes (Solanum tuberosum L. cv. Russet Burbank) grown in Oregon at Klamath Falls, Madras, and Ontario were subjected to repeated foliar methanol treatments during the 1993 season. Methanol was applied at 20%, 40%, and 80% concentration with Triton X-100 sticker-spreader at 0.1%, and methanol was applied at 20% and 40% without Triton X-100. Methanol had no effect on tuber yield, size distribution, grade, or specific gravity at any location. Tuber stem-end fry color showed no methanol response at the two locations where it was measured. Soil water potential (measured at Madras and Ontario) showed no difference in water-use efficiency between methanol-treated and nontreated potato plants.
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49

Inaba, Satoshi. « Acid–Base Catalytic Effects on Reduction of Methanol in Hot Water ». Catalysts 9, no 4 (21 avril 2019) : 373. http://dx.doi.org/10.3390/catal9040373.

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We have performed a number of quantum chemical simulations to examine the reduction process of methanol in hot water. Methanol is converted into a methane by capturing a hydrogen molecule and leaving a water molecule behind. The required energy for the reduction is too high to proceed in the gas phase. The energy barrier for the reduction of methanol is reduced by the catalytic effect of water molecules when we consider the reduction in aqueous solution. However, the calculated reduction rate is still much slower than that found experimentally. The ion product of water tends to increase in hot water, even though it eventually decreases at the high temperature of supercritical water. It is valuable to consider the acid–base catalytic effects on the reduction of methanol in hot water. The significant reduction of the energy barrier is accomplished by the acid–base catalytic effects due to hydronium or hydroxyde. Mean collision time between a hydronium and a methanol in hot water is shorter than the reduction time, during which a methanol is converted into a methane. The calculated reduction rate with the acid–base catalytic effects agrees well with that determined by laboratory experiments. The present study reveals a crucial role of the acid–base catalytic effects on reactions in hot water.
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Ullah, Aubaid, Nur Awanis Hashim, Mohamad Fairus Rabuni et Mohd Usman Mohd Junaidi. « A Review on Methanol as a Clean Energy Carrier : Roles of Zeolite in Improving Production Efficiency ». Energies 16, no 3 (2 février 2023) : 1482. http://dx.doi.org/10.3390/en16031482.

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Clean methanol can play an important role in achieving net zero emission targets by decarbonizing the energy and chemical sectors. Conventionally, methanol is produced by using fossil fuel as raw material, which releases a significant amount of greenhouse gases (GHGs) into the environment. Clean methanol, which is produced by hydrogen (H2) from renewable sources (green H2) and captured carbon dioxide (CO2), is totally free from the influence of fossil fuel. Due to its vast applications, clean methanol has potential to substitute for fossil fuels while preventing further GHGs emissions. This review addresses the feasibility of producing clean methanol from renewable resources, i.e., green H2 and captured CO2. Availability of these raw materials is the main factor involved in establishing the circular economy of methanol, therefore, their potential sources and the possible pathways to access these sources are also summarized. Renewable energy sources such as solar, wind and biomass should be utilized for producing green H2, while CO2 captured from air, and more likely from point emission sources, can be recycled to produce clean methanol. After producing methanol from CO2 and H2, the removal of by-product water by distillation is a big challenge due its high energy consumption. An alternative approach for this methanol-water separation is membrane technology, which is an energy saving option. Water-selective zeolite membranes can separate water post-synthesis, as well as during the synthesis. Production efficiency of methanol can be enhanced by utilizing zeolite membranes inside the methanol synthesis reactor. Furthermore, CO2 conversion as well as methanol selectivity, purity and yield can also be increased significantly by selectively removing by-product water using a zeolite membrane reactor.
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