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Journal articles on the topic 'Acetaldehyde Spectra'

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Published: 10 December 2022
Last updated: 29 January 2023

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1

Hudson, Reggie L., and Robert F. Ferrante. "Quantifying acetaldehyde in astronomical ices and laboratory analogues: IR spectra, intensities, 13C shifts, and radiation chemistry." Monthly Notices of the Royal Astronomical Society 492, no. 1 (December 11, 2019): 283–93. http://dx.doi.org/10.1093/mnras/stz3323.

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ABSTRACT Acetaldehyde is of interest to astrochemists for its relevance to both interstellar and cometary chemistry, but little infrared (IR) spectral data have been published for the solid phases of this compound. Here we present IR spectra of three forms of solid acetaldehyde, with spectra for one form being published for the first time. Direct measurements of band strengths and absorption coefficients also are reported for the first time for amorphous aldehyde, the form of greatest interest for astrochemical work. An acetaldehyde band strength at ∼1350 cm−1 that has been used as a reference for about 20 yr is seen to be in error by about 80 per cent when compared to the direct measurements presented here. Spectra and peak positions also are presented for H13C(O)13CH3, and then used for the first identification of ketene as a radiation product of solid acetaldehyde.
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2

Jen, Shih-Hui, Tsing-Jung Hsu, and I.-Chia Chen. "Fluorescence lifetime of rovibrational states of h4-acetaldehyde and spectra of d4-acetaldehyde." Chemical Physics 232, no. 1-2 (June 1998): 131–39. http://dx.doi.org/10.1016/s0301-0104(98)00097-4.

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3

Yakovlev, N. N., and I. A. Godunov. "The electronic spectra of acetaldehyde-h4 and -d4." Canadian Journal of Chemistry 70, no. 3 (March 1, 1992): 931–34. http://dx.doi.org/10.1139/v92-125.

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The [Formula: see text] electronic absorption spectra of acetaldehyde-h4 and -d4 were recorded in the vapour phase at room temperature. The major experimental requirement was a high pressure × path length (650 Torr × 140 m). The vibrational structure of these electronic transitions was interpreted in terms of the torsional modes [Formula: see text] and [Formula: see text] attached to the [Formula: see text] out-of-plane bending mode. The main CH3CHO results agreed with those obtained earlier (Moule and Ng); the values of the [Formula: see text] transition and torsional barrier height were 27240.1 and 590 cm−1 respectively. Three inversion (out-of-plane bending) energy levels in the excited [Formula: see text] state were found and the inversion potential function was determined with a barrier height of 1110 cm−1. The CD3CDO spectrum confirmed the CH3CHO analysis. The values of the [Formula: see text] transition and torsional barrier height were equal to 27270 and 610 cm−1. Keywords: vibronic spectrum, acetaldehyde, molecular structure.
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4

Elkeurti, M., L. H. Coudert, I. R. Medvedev, A. Maeda, F. C. De Lucia, A. R. W. McKellar, N. Moazzen-Ahmadi, D. Appadoo, and S. Toumi. "The microwave and far infrared spectra of acetaldehyde-." Journal of Molecular Spectroscopy 263, no. 2 (October 2010): 145–49. http://dx.doi.org/10.1016/j.jms.2010.07.005.

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5

Guidolin, Valeria, Erik S. Carlson, Andrea Carrà, Peter W. Villalta, Laura A. Maertens, Stephen S. Hecht, and Silvia Balbo. "Identification of New Markers of Alcohol-Derived DNA Damage in Humans." Biomolecules 11, no. 3 (February 27, 2021): 366. http://dx.doi.org/10.3390/biom11030366.

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Alcohol consumption is a risk factor for the development of several cancers, including those of the head and neck and the esophagus. The underlying mechanisms of alcohol-induced carcinogenesis remain unclear; however, at these sites, alcohol-derived acetaldehyde seems to play a major role. By reacting with DNA, acetaldehyde generates covalent modifications (adducts) that can lead to mutations. Previous studies have shown a dose dependence between levels of a major acetaldehyde-derived DNA adduct and alcohol exposure in oral-cell DNA. The goal of this study was to optimize a mass spectrometry (MS)-based DNA adductomic approach to screen for all acetaldehyde-derived DNA adducts to more comprehensively characterize the genotoxic effects of acetaldehyde in humans. A high-resolution/-accurate-mass data-dependent constant-neutral-loss-MS3 methodology was developed to profile acetaldehyde-DNA adducts in purified DNA. This resulted in the identification of 22 DNA adducts. In addition to the expected N2-ethyldeoxyguanosine (after NaBH3CN reduction), two previously unreported adducts showed prominent signals in the mass spectra. MSn fragmentation spectra and accurate mass were used to hypothesize the structure of the two new adducts, which were then identified as N6-ethyldeoxyadenosine and N4-ethyldeoxycytidine by comparison with synthesized standards. These adducts were quantified in DNA isolated from oral cells collected from volunteers exposed to alcohol, revealing a significant increase after the exposure. In addition, 17 of the adducts identified in vitro were detected in these samples confirming our ability to more comprehensively characterize the DNA damage deriving from alcohol exposures.
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6

Kleiner, I., F. J. Lovas, and M. Godefroid. "Microwave Spectra of Molecules of Astrophysical Interest. XXIII. Acetaldehyde." Journal of Physical and Chemical Reference Data 25, no. 4 (July 1996): 1113–210. http://dx.doi.org/10.1063/1.555983.

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7

Makulski, Włodzimierz, and Agata J. Wikieł. "Liquid and gas phase NMR spectra of 13CH313CHO acetaldehyde." Journal of Molecular Structure 1152 (January 2018): 145–53. http://dx.doi.org/10.1016/j.molstruc.2017.09.066.

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8

Terwisscha van Scheltinga, J., N. F. W. Ligterink, A. C. A. Boogert, E. F. van Dishoeck, and H. Linnartz. "Infrared spectra of complex organic molecules in astronomically relevant ice matrices." Astronomy & Astrophysics 611 (March 2018): A35. http://dx.doi.org/10.1051/0004-6361/201731998.

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Context. The number of identified complex organic molecules (COMs) in inter- and circumstellar gas-phase environments is steadily increasing. Recent laboratory studies show that many such species form on icy dust grains. At present only smaller molecular species have been directly identified in space in the solid state. Accurate spectroscopic laboratory data of frozen COMs, embedded in ice matrices containing ingredients related to their formation scheme, are still largely lacking.Aim. This work provides infrared reference spectra of acetaldehyde (CH3CHO), ethanol (CH3CH2OH), and dimethyl ether (CH3OCH3) recorded in a variety of ice environments and for astronomically relevant temperatures, as needed to guide or interpret astronomical observations, specifically for upcoming James Webb Space Telescope observations.Methods. Fourier transform transmission spectroscopy (500–4000 cm−1/20–2.5 μm, 1.0 cm−1 resolution) was used to investigate solid acetaldehyde, ethanol and dimethyl ether, pure or mixed with water, CO, methanol, or CO:methanol. These species were deposited on a cryogenically cooled infrared transmissive window at 15 K. A heating ramp was applied, during which IR spectra were recorded until all ice constituents were thermally desorbed.Results. We present a large number of reference spectra that can be compared with astronomical data. Accurate band positions and band widths are provided for the studied ice mixtures and temperatures. Special efforts have been put into those bands of each molecule that are best suited for identification. For acetaldehyde the 7.427 and 5.803 μm bands are recommended, for ethanol the 11.36 and 7.240 μm bands are good candidates, and for dimethyl ether bands at 9.141 and 8.011 μm can be used. All spectra are publicly available in the Leiden Database for Ice.
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9

Sheps, Leonid, Ashley M. Scully, and Kendrew Au. "UV absorption probing of the conformer-dependent reactivity of a Criegee intermediate CH3CHOO." Phys. Chem. Chem. Phys. 16, no. 48 (2014): 26701–6. http://dx.doi.org/10.1039/c4cp04408h.

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Transient absorption probing of a Criegee intermediate acetaldehyde oxide reveals the UV spectra of the two possible conformers, syn- and anti-CH3CHOO, and enables direct measurements of conformer-dependent reactivity.
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10

Zagorodskikh, S., M. Vapa, O. Vahtras, V. Zhaunerchyk, M. Mucke, J. H. D. Eland, R. J. Squibb, et al. "An experimental and theoretical study of core–valence double ionisation of acetaldehyde (ethanal)." Physical Chemistry Chemical Physics 18, no. 4 (2016): 2535–47. http://dx.doi.org/10.1039/c5cp05758b.

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Core–valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique and analyzed by means of quantum chemical calculations of transition energies.
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11

Negri, Fabrizia, and Giorgio Orlandi. "The Resonance Raman Spectra Of Biologically Relevant Polyene Derivatives in T1: A Theoretical Investigation." Laser Chemistry 19, no. 1-4 (January 1, 1999): 191–94. http://dx.doi.org/10.1155/1999/59018.

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The vibrational structure of the T1 resonance Raman spectra of β-ionylidene acetaldehyde (C15 aldehyde) and retinal are analyzed with the help of semiempirical quantum chemical calculations. The T1 equilibrium structures and vibrational force fields, along with the structure in the Tn state which is in resonance with the exciting wavelength, are obtained and employed to model the spectra under the assumption of a dominant Franck–Condon mechanism.
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12

Kono, Takumi, Masao Takayanagi, and Ichiro Hanazaki. "The C=O Stretching Frequency in the S1 (π* - n) State of Acetaldehyde and its Deuterated Derivatives Determined With the Photofragment Excitation Spectroscopy." Laser Chemistry 15, no. 2-4 (January 1, 1995): 249–59. http://dx.doi.org/10.1155/1995/75278.

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The vibrational structure was recorded for the S1 (π* - n) state of acetaldehyde (CH3CHO) and its deuterated derivatives (CH3CDO, CD3CHO and CD3CDO up to ∼3500 cm-1above the 0-0 bands with the LIF (laser induced fluorescence) and PHOFEX (photofragment excitation) techniques. In the PHOFEX spectroscopy, the yield of the formyl radical, HCO(X ˜) or DCO(X ˜), produced in the photodissociation of acetaldehyde is measured against the excitation frequency. The yield was determined by monitoring one of the rotational lines in the B˜ ← X˜ transition of the formyl radical by the LIF technique. This is the first measurement of the vibronic structure of acetaldehydes in supersonic jets above the dissociation threshold where they are non-fluorescent. The results have made it possible to locate v4 (the C=O stretching) and 2v4 bands unequivocally; the v4 fundamentals at 1217, 1189, 1210 and 1178 cm-1 above the 0-0 band for CH3CHO, CH3CDO, CD3CHO and CD3CDO, respectively. The corresponding overtone (2v4) bands are observed, respectively, at 2414, 2350, 2399 and 2334cm-1. All the vibronic bands newly observed in the PHOFEX spectra are found to be interpreted as the combinations of v4 and 2v4 with the modes appearing in the lower frequency (< 1200 cm-1) region, which consist of v10 (the C—C—O in-plane bending), v14 (the C=O out-of-plane wagging) and v15 (the methyl torsion).
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13

Moruzzi, Giovanni, and Adriana Predoi-Cross. "The Ritz program for assigning rotational and rovibrational transitions in asymmetric-top molecules." Canadian Journal of Physics 98, no. 6 (June 2020): 499–505. http://dx.doi.org/10.1139/cjp-2019-0471.

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The Ritz program is a user-interactive software package that simulates and enables the assignment of spectra of asymmetric top molecules, up to high rotational quantum numbers. The set of initial assignments can be extended using generated predictions for line positions. The graphical interface of the program handles wide spectral features corresponding to overlapped lines by fitting the expected number of profiles to the experimental contour. Features of the program allow for the detection and examination of Coriolis interactions. Initially designed to work for methanol and its isotopologues, the program has been modified to assign the spectra of cyanamide, hydrazine, acetaldehyde, and oxetane. An extension of the program, LaseRitz, has been developed for the assignment and prediction of optically pumped far-infrared laser transitions. Our paper presents a description of how the Ritz program works and provides an overview of studies carried-out using this software.
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14

PRINCE, K. C., R. RICHTER, M. DE SIMONE, and M. CORENO. "X-RAY ABSORPTION SPECTRA OF SOME SMALL POLYATOMIC MOLECULES." Surface Review and Letters 09, no. 01 (February 2002): 159–64. http://dx.doi.org/10.1142/s0218625x02002026.

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We report the Near Edge X-ray Absorption Fine Structure Spectra (NEXAFS) of a series of oxygen-containing organic molecules, namely formaldehyde, acetaldehyde, acetone, formic acid, methanol and dimethyl ether (DME), measured with high resolution at the carbon and oxygen edges. A vibrational progression has been observed at the oxygen 1s → π* resonance of formaldehyde, indicating that this state is bound with an excited state C=O stretching frequency of 136 meV. The spectra are compared with previous measurements and the applicability of the chromophore concept is tested for the functional groups present in these molecules.
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15

Védova, C. O. Della, and O. Sala. "Raman and infrared spectra and photochemical behaviour of acetaldehyde isolated in matrices." Journal of Raman Spectroscopy 22, no. 9 (September 1991): 505–7. http://dx.doi.org/10.1002/jrs.1250220906.

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16

Terwisscha van Scheltinga, J., N. F. W. Ligterink, A. C. A. Boogert, E. F. van Dishoeck, and H. Linnartz. "Infrared spectra of complex organic molecules in astronomically relevant ice matrices." Proceedings of the International Astronomical Union 15, S350 (April 2019): 356–57. http://dx.doi.org/10.1017/s1743921319008780.

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AbstractThe identification of complex organic molecules, COMs, in inter- and circumstellar gas phase environments is steadily increasing. The formation of such COMs takes largely place on the icy dust grains, as has been shown in recent laboratory studies. Until now solid state features of smaller molecular species have been directly identified in these environments. The presented work on acetaldehyde (CH3CHO), ethanol (CH3CH2OH), and dimethyl ether (CH3OCH3) in different astronomically relevant ice environments and for temperatures in the range 15 to 160 Kelvin, provides the necessary tools to guide or interpret astronomical observations, specifically for upcoming James Webb Space Telescope observations.
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17

Maes, H., G. Wlodarczak, D. Boucher, and J. Demaison. "The Millimeter- and Submillimeter-Wave Spectra of Acetaldehyde: Centrifugal Distortion and Internal Rotation Analysis." Zeitschrift für Naturforschung A 42, no. 1 (January 1, 1987): 97–102. http://dx.doi.org/10.1515/zna-1987-0117.

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141 internal rotation doublets (282 transitions, among which 174 new measurements) of acetaldehyde in its ground torsional state have been measured up to 600 GHz (J ≦ 32). An overall fit of the measurements (including the lines identified by previous workers) using the Internal Axis Method has allowed us to accurately determine the rotational, centrifugal distortion and internal rotation constants. The quality of the fit is good enough to permit the accurate prediction of transition frequencies of possible astrophysical interest.
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18

Findsen, Leonore A., Howard L. Fang, Robert L. Swofford, and Robert R. Birge. "Theoretical description of the overtone spectra of acetaldehyde using the local mode approach." Journal of Chemical Physics 84, no. 1 (January 1986): 16–27. http://dx.doi.org/10.1063/1.450166.

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19

Thompson, David B., De Ji, Shih-Ying Chen, and David M. Hanson. "Excitation and decay spectra of core-excited resonances in acetaldehyde, propionaldehyde and acetone." Journal of Physics B: Atomic, Molecular and Optical Physics 32, no. 24 (December 2, 1999): 5711–24. http://dx.doi.org/10.1088/0953-4075/32/24/308.

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20

Hergenhahn, U., A. Rüdel, K. Maier, A. M. Bradshaw, R. F. Fink, and A. T. Wen. "The resonant Auger spectra of formic acid, acetaldehyde, acetic acid and methyl formate." Chemical Physics 289, no. 1 (April 2003): 57–67. http://dx.doi.org/10.1016/s0301-0104(02)00795-4.

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21

Erker, Gerhard, and Uwe Korek. "Stereoselektive Insertion von Aldehyden und Ketonen in die Metall-Kohlenstoff-Bindung eines (η6-Fulven)titan-Komplexes / Stereoselective Insertion of Aldehydes and Ketones into the Metal-Carbon Bond of a (η6-Fulvene)titanium Complex." Zeitschrift für Naturforschung B 44, no. 12 (December 1, 1989): 1593–98. http://dx.doi.org/10.1515/znb-1989-1222.

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Thermolysis of Bis(η-methylcyclopentadienyl)diphenyltitanium (6) at 80°C yields benzene and (η6-fulvene)(η-methylcyclopentadienyl)phenyltitanium (8). Complex 8 reacts with various aldehydes and ketones by insertion into the Ti—CH2C5H4 σ-bond to stereoselectively form the metallacyclic chiral metallocene complexes [xxx] 10a—d. Difference NOE 1H NMR spectra of the acetaldehyde insertion product 10c (R1 = H, R2 = CH3) have revealed a cis-arrangement of the methyl substituent and the titanium bound σ-phenyl ligand at the central metallacyclic ring system.
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22

Wei, Mingzhuo, Zhijun Li, Peijiao Chen, Lei Sun, Shilin Kang, Tianwei Dou, Yang Qu, and Liqiang Jing. "N-Rich Doped Anatase TiO2 with Smart Defect Engineering as Efficient Photocatalysts for Acetaldehyde Degradation." Nanomaterials 12, no. 9 (May 5, 2022): 1564. http://dx.doi.org/10.3390/nano12091564.

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Nitrogen (N) doping is an effective strategy for improving the solar-driven photocatalytic performance of anatase TiO2, but controllable methods for nitrogen-rich doping and associated defect engineering are highly desired. In this work, N-rich doped anatase TiO2 nanoparticles (4.2 at%) were successfully prepared via high-temperature nitridation based on thermally stable H3PO4-modified TiO2. Subsequently, the associated deep-energy-level defects such as oxygen vacancies and Ti3+ were successfully healed by smart photo-Fenton oxidation treatment. Under visible-light irradiation, the healed N-doped TiO2 exhibited a ~2-times higher activity of gas-phase acetaldehyde degradation than the non-treated one and even better than standard P25 TiO2 under UV-visible-light irradiation. The exceptional performance is attributed to the extended spectral response range from N-rich doping, the enhanced charge separation from hole capturing by N-doped species, and the healed defect levels with the proper thermodynamic ability for facilitating O2 reduction, depending on the results of ∙O2− radicals and defect measurement by electron spin resonance, X-ray photoelectron spectroscopy, atmosphere-controlled surface photovoltage spectra, etc. This work provides an easy and efficient strategy for the preparation of high-performance solar-driven TiO2 photocatalysts.
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23

Journal, Baghdad Science. "Synthesis of New Mannich Bases from Indole Derivatives." Baghdad Science Journal 9, no. 1 (March 4, 2012): 168–77. http://dx.doi.org/10.21123/bsj.9.1.168-177.

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This work includes two steps of synthesis, the first one is the synthesis of indole which was prepared according to literature of the reaction of phenyl hydrazine with acetaldehyde in glacial acetic acid afforded phenyl hydrazone of acetaldehyde , this product was fused with zinc chloride to give the indole.Reaction of cyclohexanone with phenyl hydrazine using the same procedure for the preparing giving 1,2,3,4-Tetrahydrocarbazole.Second step involved synthesis of a series of (17) of mannich bases derivatives of indole and 1,2,3,4-Tetrahydrocarbazle. Mannich reaction involves the condensation of aldehyde usually formaldehyde with different secondary amine and with compound containing an activated hydrogen.The reaction illustrated by the following equation :R2NH+HCHO+RH?R2N-CH2-R+H2O These compounds were characterized by U.V , FT-IR and 1H-NMR spectra for two compounds. The secondary amines that used to prepare mannich bases are:N-methyl –N-phenyl amine, N,N-dimethyl amine, N,N- diphenyl amine, N-ethyl –N- phenyl amine, N,N-di-n-propyl amine, pyrrolidine, morpholine, N- methyl pipyridine, N,N-dibenzyl amine, N,N-di –n-butyl amine and N,N-di ethyl amine.
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24

Piliai, Lesia, David Tomeček, Martin Hruška, Ivan Khalakhan, Jaroslava Nováková, Přemysl Fitl, Roman Yatskiv, et al. "New Insights towards High-Temperature Ethanol-Sensing Mechanism of ZnO-Based Chemiresistors." Sensors 20, no. 19 (September 30, 2020): 5602. http://dx.doi.org/10.3390/s20195602.

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In this work, we investigate ethanol (EtOH)-sensing mechanisms of a ZnO nanorod (NRs)-based chemiresistor using a near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). First, the ZnO NRs-based sensor was constructed, showing good performance on interaction with 100 ppm of EtOH in the ambient air at 327 °C. Then, the same ZnO NRs film was investigated by NAP-XPS in the presence of 1 mbar oxygen, simulating the ambient air atmosphere and O2/EtOH mixture at the same temperature. The partial pressure of EtOH was 0.1 mbar, which corresponded to the partial pressure of 100 ppm of analytes in the ambient air. To better understand the EtOH-sensing mechanism, the NAP-XPS spectra were also studied on exposure to O2/EtOH/H2O and O2/MeCHO (MeCHO = acetaldehyde) mixtures. Our results revealed that the reaction of EtOH with chemisorbed oxygen on the surface of ZnO NRs follows the acetaldehyde pathway. It was also demonstrated that, during the sensing process, the surface becomes contaminated by different products of MeCHO decomposition, which decreases dc-sensor performance. However, the ac performance does not seem to be affected by this phenomenon.
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25

Karapinar, Emin, Orhan Karabulut, and Nazan Karapinar. "Thermal, Electrical, and Optical Properties of Synthesized (1E, 2E)-(4-bromophenyl)(hydroxyimino)acetaldehyde Oxime Complexes." Journal of Chemistry 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/256983.

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The (1E, 2E)-(4-bromophenyl)(hydroxyimino)acetaldehyde oxime complexes, [ML2], M = Co(II), Cu(II), and Ni(II), were synthesized and characterized by elemental analysis, magnetic susceptibility, FT-IR spectra, and thermal analysis techniques. The optical band gap of this ligand and its complexes were determined by UV-vis spectrophotometer in the wavelength range 300–800 nm. A decrease in the energy band gap of the [CoL2], [NiL2], and [CuL2] complexes has been observed compared with LH ligand. Temperature-dependent conductivity measurements showed that all samples behave like semiconductor. Activation energies calculated from Arrhenius plots showed that the conduction occurs via both intramolecular and the intermolecular processes.
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26

Moule, D. C., and K. H. K. Ng. "The conformational changes accompanying the triplet–singlet electronic excitation of acetaldehyde, CH3CHO." Canadian Journal of Chemistry 63, no. 7 (July 1, 1985): 1378–81. http://dx.doi.org/10.1139/v85-236.

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The first electronic absorption system of acetaldehyde was recorded in the vapour phase at room temperature. The many-banded spectrum proved to be very complex and it was only at the extreme red edge of the absorption that the pattern became simple enough to analyze. The major experimental requirement was a high pressure × path length (500 Torr × 168 m). Spectra were interpreted in terms of the torsional mode ν′15 and ν″15 attached to the ν′14 out-of-plane bending mode. Both modes were highly Franck–Condon active and the [Formula: see text] band at 27240.4 cm−1 was not directly observed. The barrier to rotation of the methyl group was 618.5 cm−1. More surprising was the observation that the methyl group undergoes a rotation from a [Formula: see text] eclipsed configuration to a staggered configuration. The intensity of the ν′14 quantum addition and its position in the spectrum suggest that the aldehydic hydrogen is nonplanar in the ã state.
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27

Zhao, Fei, Chunyu Wang, Xianjing Liu, Qingyue Luo, and Ling Zhu. "Purification of fuel ethanol engine exhaust with platinum-loaded Ce0.5Zr0.5O2 catalyst." Nanomaterials and Nanotechnology 9 (January 1, 2019): 184798041988667. http://dx.doi.org/10.1177/1847980419886673.

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This work aimed at exploring a new kind of purification catalysts for fuel ethanol engine exhaust. Platinum loaded on Ce0.5Zr0.5O2 was prepared by impregnation method and characterized by X-ray diffraction, Brunner–Emmet–Teller measurements (BET), temperature-programmed reduction of hydrogen, scanning electron microscope, and X-ray photoelectron spectra. The three-way catalyst platinum/ceria–zirconia/fw is prepared with the paste ball mill coating technique. And the catalytic performance is evaluated under simulated fuel ethanol engine exhaust gas condition. The catalysts not only show excellent low-temperature performances and several-way catalytic activities for carbon monoxide, hydrocarbons, nitrogen oxides, and acetaldehyde but also have better high-temperature resistance. The addition of sulfur dioxide to feedstream degrades the performances of the catalysts.
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28

Grue-Sørensen, Gunnar, and Ian D. Spenser. "The biosynthesis of ephedrine." Canadian Journal of Chemistry 67, no. 6 (June 1, 1989): 998–1009. http://dx.doi.org/10.1139/v89-152.

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It is shown by 13C nuclear magnetic resonance spectroscopy that the labelled C2 fragment of [2,3-13C2]pyruvic acid is transferred intact into the C-methyl group and the adjacent carbon atom of the Ephedra alkaloids, norephedrine, ephedrine, norpseudoephedrine, and pseudoephedrine, in growing plants of Ephedragerardiana. This finding serves to identify pyruvate as the elusive precursor of the aliphatic C2 terminus of the skeleton of the alkaloids. In earlier experiments with C-labelled substrates, label from [3-14C]pyruvic acid was incorporated mainly, but not exclusively, into the C-methyl group of ephedrine, and label from [2-14C]pyruvate was incorporated similarly into the carbon atom adjacent to the C-methyl group. A C6–C1 unit related to benzaldehyde or benzoic acid has long been known to generate the benzylic fragment of the carbon skeleton of the Ephedra alkaloids. It is likely that the carbon skeleton of ephedrine is generated from pyruvate and either benzaldehyde or benzoic acid, by a reaction analogous to the formation of acetoin or diacetyl from pyruvate and acetaldehyde or acetic acid, respectively. Keywords: biosynthesis of ephedrine, Ephedra alkaloids, 13C NMR spectra, ephedrine, biosynthesis of pyruvic acid, incorporation into ephedrine13C NMR spectra.
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29

Rassem, Hesham Hussein, Abdurahman Hamid Nour, and Rosli Mohammed Yunus. "GC-MS ANALYSIS OF BIOACTIVE CONSTITUENTS OF JASMINE FLOWER." Journal of Chemical Engineering and Industrial Biotechnology 4, no. 1 (September 1, 2018): 52–59. http://dx.doi.org/10.15282/jceib.v4i1.3883.

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Gas Chromatography-Mass Spectrometry (GC-MS) the best technique to identified the compounds of essential oils by comparison of mass spectra data obtained from the sample with that taken from pure commercially available standards injected under the same conditions. To characterize the chemical constituents of Hibiscus Flower using GC-MS, the shade dried flower powder was extracted with methanol by using Microwave-assisted Hydrodistillation (MAHD). The GC-MS analysis provided different peaks determining the presence of ten compounds. These compounds havebiological activity namely 2-Phenylthiolane (57.31%), Cyclohexene, 3-ethenyl- (25.91%), Acetaldehyde (12.70%), N-Methylallylamine (9.99%), ropanamide (6.79%) and Phthalic acid, bis (7-methyloctyl) ester (5.21%). From the results, it can be concluded that Jasmine flower extract shows the presence of 10 phytocompounds. The presence of various bioactive compounds justifies the use of the jasmine flower for various ailments by traditional practitioners.
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Teipel, Jan C., Thomas Hausler, Katharina Sommerfeld, Andreas Scharinger, Stephan G. Walch, Dirk W. Lachenmeier, and Thomas Kuballa. "Application of 1H Nuclear Magnetic Resonance Spectroscopy as Spirit Drinks Screener for Quality and Authenticity Control." Foods 9, no. 10 (September 24, 2020): 1355. http://dx.doi.org/10.3390/foods9101355.

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Due to legal regulations, the rise of globalised (online) commerce and the need for public health protection, the analysis of spirit drinks (alcoholic beverages >15% vol) is a task with growing importance for governmental and commercial laboratories. In this article a newly developed method using nuclear magnetic resonance (NMR) spectroscopy for the simultaneous determination of 15 substances relevant to assessing the quality and authenticity of spirit drinks is described. The new method starts with a simple and rapid sample preparation and does not need an internal standard. For each sample, a group of 1H-NMR spectra is recorded, among them a two-dimensional spectrum for analyte identification and one-dimensional spectra with suppression of solvent signals for quantification. Using the Pulse Length Based Concentration Determination (PULCON) method, concentrations are calculated from curve fits of the characteristic signals for each analyte. The optimisation of the spectra, their evaluation and the transfer of the results are done fully automatically. Glucose, fructose, sucrose, acetic acid, citric acid, formic acid, ethyl acetate, ethyl lactate, acetaldehyde, methanol, n-propanol, isobutanol, isopentanol, 2-phenylethanol and 5-(hydroxymethyl)furfural (HMF) can be quantified with an overall accuracy better than 8%. This new NMR-based targeted quantification method enables the simultaneous and efficient quantification of relevant spirit drinks ingredients in their typical concentration ranges in one process with good accuracy. It has proven to be a reliable method for all kinds of spirit drinks in routine food control.
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31

Ioppolo, S., B. A. McGuire, M. A. Allodi, and G. A. Blake. "THz and mid-IR spectroscopy of interstellar ice analogs: methyl and carboxylic acid groups." Faraday Discuss. 168 (2014): 461–84. http://dx.doi.org/10.1039/c3fd00154g.

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A fundamental problem in astrochemistry concerns the synthesis and survival of complex organic molecules (COMs) throughout the process of star and planet formation. While it is generally accepted that most complex molecules and prebiotic species form in the solid phase on icy grain particles, a complete understanding of the formation pathways is still largely lacking. To take full advantage of the enormous number of available THz observations (e.g.,Herschel Space Observatory, SOFIA, and ALMA), laboratory analogs must be studied systematically. Here, we present the THz (0.3–7.5 THz; 10–250 cm−1) and mid–IR (400–4000 cm−1) spectra of astrophysically-relevant species that share the same functional groups, including formic acid (HCOOH) and acetic acid (CH3COOH), and acetaldehyde (CH3CHO) and acetone ((CH3)2CO), compared to more abundant interstellar molecules such as water (H2O), methanol (CH3OH), and carbon monoxide (CO). A suite of pure and mixed binary ices are discussed. The effects on the spectra due to the composition and the structure of the ice at different temperatures are shown. Our results demonstrate that THz spectra are sensitive to reversible and irreversible transformations within the ice caused by thermal processing, suggesting that THz spectra can be used to study the composition, structure, and thermal history of interstellar ices. Moreover, the THz spectrum of an individual species depends on the functional group(s) within that molecule. Thus, future THz studies of different functional groups will help in characterizing the chemistry and physics of the interstellar medium (ISM).
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32

Andrews, A. M., M. Yu Tretyakov, B. H. Pate, G. T. Fraser, and I. Kleiner. "Fourier-transform infrared and jet-cooled diode-laser spectra of the 867 cm-1 v 9 band of acetaldehyde." Molecular Physics 84, no. 1 (January 1995): 201–10. http://dx.doi.org/10.1080/00268979500100151.

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33

Dereli, Ö., Y. Erdogdu, and M. T. Gulluoglu. "Study on molecular structure and vibrational spectra of (triphenylphosphoranylidene) acetaldehyde using DFT: A combined experimental and quantum chemical approach." Journal of Molecular Structure 1012 (March 2012): 105–12. http://dx.doi.org/10.1016/j.molstruc.2011.12.040.

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34

Coen, Muireann, Jennifer Bodkin, Damla Power, William A. Bubb, Uwe Himmelreich, Philip W. Kuchel, and Tania C. Sorrell. "Antifungal Effects on Metabolite Profiles of Medically Important Yeast Species Measured by Nuclear Magnetic Resonance Spectroscopy." Antimicrobial Agents and Chemotherapy 50, no. 12 (December 2006): 4018–26. http://dx.doi.org/10.1128/aac.00439-06.

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ABSTRACT Drug-induced inhibition of fungal growth is used in the diagnostic laboratory to predict therapeutic efficacy but is relatively slow, and determination of endpoints can be problematic. Nuclear magnetic resonance (NMR) spectroscopy identifies the metabolic complement of microorganisms while monitoring utilization of constituents of the incubation medium. This technique may provide a rapid and objective indicator of antifungal effects. We evaluated the effects of caspofungin, amphotericin B (AMB), and voriconazole on metabolic profiles of yeast species cultured in RPMI-2% glucose-morpholinepropanesulfonic acid buffer in microtiter plates in a proof-of-principle study. 1H NMR spectra were obtained using Bruker NMR spectrometers at 1H frequencies of 600 and 360 MHz. Metabolites were identified by two-dimensional correlation NMR spectra, and relative peak integrals were calculated from one-dimensional 1H NMR spectra. MICs were determined by a modification of the Clinical and Laboratory Standards Institute broth microdilution method M27-A. Utilization of glucose and branched-chain and aromatic amino acid substrates was accompanied by fungal production of acetate, acetaldehyde, ethanol, formate, fumarate, glycerol, lactate, pyruvate, and succinate. Clear-cut metabolic endpoints indicating a greater than 50% reduction in substrate utilization and fungal metabolite production which correlated with MICs were noted at 16 and 24 h for all three drugs. At 8 h, reductions of greater than 50% for selected metabolites were noted for caspofungin and AMB. Direct NMR-based observation of metabolic alterations in yeast cultures reveals changes in key metabolic pathways and should be evaluated formally as a rapid technique for determining susceptibility to antifungal drugs.
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35

Zwiener, C., T. Glauner, and F. H. Frimmel. "LC-ESI/MS/MS analysis with derivatization applied to polar disinfection by-products in water treatment." Water Supply 3, no. 1-2 (March 1, 2003): 321–28. http://dx.doi.org/10.2166/ws.2003.0120.

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Chlorination and ozonation experiments under conditions close to drinking water treatment were carried out with two different tap waters with low DOC content and water from a bog lake with high natural organic matter content. THM formation was low and in the range of 10 μg/L. Derivatization with dinitrophenylhydrazine and HPLC/tandem mass spectrometry were applied to measure carbonyl DBPs by precursor ion scans at m/z 163 for aldehydes and at m/z 182 for dicarbonyls. Formaldehyde, acetaldehyde, glyoxal, and methylglyoxal were formed by chlorination and ozonation. Ozonation produced the highest levels of carbonyls, in particular in the tap water samples. A strategy for structure suggestion and identification of unknown compounds on the basis of collision-induced dissociation (CID) mass spectra (MS) is given. The resulting structures are carbonyls with additional hydroxy and carboxy groups and serve for choice or synthesis of standard compounds for further identification. The possibilities and limits of compound identification are discussed.
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36

Rezaei, Golbon, and Giovanni Meloni. "Study of the Synchrotron Photoionization Oxidation of Alpha-Angelica Lactone (AAL) Initiated by O(3P) at 298, 550, and 700 K." Molecules 26, no. 13 (July 3, 2021): 4070. http://dx.doi.org/10.3390/molecules26134070.

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In recent years, biofuels have been receiving significant attention because of their potential for decreasing carbon emissions and providing a long-term renewable solution to unsustainable fossil fuels. Currently, lactones are some of the alternatives being produced. Many lactones occur in a range of natural substances and have many advantages over bioethanol. In this study, the oxidation of alpha-angelica lactone initiated by ground-state atomic oxygen, O(3P), was studied at 298, 550, and 700 K using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Lawrence Berkeley National Lab (LBNL). Photoionization spectra and kinetic time traces were measured to identify the primary products. Ketene, acetaldehyde, methyl vinyl ketone, methylglyoxal, dimethyl glyoxal, and 5-methyl-2,4-furandione were characterized as major reaction products, with ketene being the most abundant at all three temperatures. Possible reaction pathways for the formation of the observed primary products were computed using the CBS–QB3 composite method.
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37

Golec, Barbara, Magdalena Sałdyka, and Zofia Mielke. "Photo-Induced Reactions between Glyoxal and Hydroxylamine in Cryogenic Matrices." Molecules 27, no. 15 (July 27, 2022): 4797. http://dx.doi.org/10.3390/molecules27154797.

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In this paper, the photochemistry of glyoxal–hydroxylamine (Gly–HA) complexes is studied using FTIR matrix isolation spectroscopy and ab initio calculations. The irradiation of the Gly–HA complexes with the filtered output of a mercury lamp (λ > 370 nm) leads to their photoconversion to hydroxyketene–hydroxylamine complexes and the formation of hydroxy(hydroxyamino)acetaldehyde with a hemiaminal structure. The first product is the result of a double hydrogen exchange reaction between the aldehyde group of Gly and the amino or hydroxyl group of HA. The second product is formed as a result of the addition of the nitrogen atom of HA to the carbon atom of one aldehyde group of Gly, followed by the migration of the hydrogen atom from the amino group of hydroxylamine to the oxygen atom of the carbonyl group of glyoxal. The identification of the products is confirmed by deuterium substitution and by MP2 calculations of the structures and vibrational spectra of the identified species.
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38

Chou, Yung-Ching, Cheng-Liang Huang, I.-Chia Chen, Chi-Kung Ni, and A. H. Kung. "Rotationally resolved spectra of transitions involving motion of the methyl group of acetaldehyde in the system à 1A″−X̃ 1A′." Journal of Chemical Physics 115, no. 11 (September 15, 2001): 5089–100. http://dx.doi.org/10.1063/1.1394751.

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39

Delbecq, Françoise, and Fabienne Vigné. "Acetaldehyde on Pt(111) and Pt/Sn(111): A DFT Study of the Adsorption Structures and of the Vibrational Spectra." Journal of Physical Chemistry B 109, no. 21 (June 2005): 10797–806. http://dx.doi.org/10.1021/jp045207j.

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40

Badescu, Virgil. "Contributions to the Interpretation of Mass Spectra of the TEOS Methoxy-Transesters. Linked Scans, Accurate Mass Measurements and M+1, M+2 Isotopic Effects." Revista de Chimie 71, no. 8 (August 31, 2020): 39–54. http://dx.doi.org/10.37358/rc.20.8.8277.

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The aim of this article is the study of the fragmentation reactions of the methoxy-transesters of tetraethoxysilane (TEOS), with structural formula (CH3O)x(C2H5O)ySi, initiated by electronic impact in the ionization chamber of a double focusing mass spectrometer. The initiation centers of fragmentation reactions for the neutral and ionized TEOS methoxy-transesters were established by quantum calculations of net atomic charges. The ions of the mass spectra of the TEOS methoxy-transesters were obtained experimentally by the B/E and B/E(1-E)1/2 linked scans. Thus, there can be written the fragmentation pathways for the primary events by B/E linked scan (cleavage of methoxy and ethoxy groups) and eliminations of neutral molecules (acetaldehyde, ethylene, formaldehyde, molecular hydrogen) by B/E(1-E)1/2 linked scan. Accurate mass measurements at high resolution (5000), double bond equivalent (DBE) for the molecular ions and fragmentation ions of the TEOS methoxy-transesters and M+1, M+2 isotopic effects were used to confirm their identification. The reaction pathways and accurate mass in mass spectrum of dimethoxydiethoxysilane (TR2M) are detailed.
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41

Chou, Yung-Ching, Cheng-Liang Huang, I.-Chia Chen, Chi-Kung Ni, and A. H. Kung. "Rotationally resolved spectra of transitions involving methyl torsion and C–C–O bend of acetaldehyde in the system of Ã1A″–X̃1A′." Journal of Chemical Physics 116, no. 3 (January 15, 2002): 1003–11. http://dx.doi.org/10.1063/1.1424312.

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42

Ding, Y., W. Y. Peng, C. L. Strand, and R. K. Hanson. "Quantitative measurements of broad-band mid-infrared absorption spectra of formaldehyde, acetaldehyde, and acetone at combustion-relevant temperatures near 5.7 µm." Journal of Quantitative Spectroscopy and Radiative Transfer 248 (June 2020): 106981. http://dx.doi.org/10.1016/j.jqsrt.2020.106981.

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43

Serebrennikov, L. V., and A. V. Golovkin. "Reaction of acetaldehyde with hydrogen peroxide at low temperatures: IR spectra in xenon matrices and calculations of intermediates and transition states." Russian Journal of Physical Chemistry 80, S1 (November 2006): S63—S71. http://dx.doi.org/10.1134/s0036024406130115.

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44

Noguchi, Shinnosuke, Toru Tokutome, and Shinji Iwamoto. "Nitrification of Nb-Modified Titanias Prepared by the Solvothermal Method and their Photocatalytic Activities under Visible-Light Irradiation." Key Engineering Materials 596 (December 2013): 43–49. http://dx.doi.org/10.4028/www.scientific.net/kem.596.43.

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Niobium modified titania samples were prepared by thermal reaction of titanium tetraisopropoxide and niobium pentaethoxide in 1,4-butanediol at 300 °C (solvothermal method), and the products were nitrified in an NH3 flow at 600 °C. The physicochemical property of the thus-obtained N-and Nb-co-doped titanias and visible-light response photocatalytic activity of FeOx-loaded N-and Nb-co-doped titanias were investigated. The N-and Nb-co-doped titanias had larger absorptions in the visible-light range as compared to the only N-doped titania samples. In ESR spectra of the Nb-modified TiO2 samples annealed at 300 °C after the nitrification, signals due to Ti3+ and oxygen vacancies, which accelerate the recombination of the photo-generated electrons and holes, were clearly observed. On the other hand, for the N-and Nb-co-doped titanias annealed at 500 °C, the signals due to Ti3+ and oxygen vacancies decreased significantly. Actually, the FeOx-loaded N-and Nb-co-doped samples annealed at 500 °C exhibited a higher photocatalytic activity for a photocatalytic decomposition of acetaldehyde under visible-light irradiation.
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45

Marsico, Antonio, Rocco Perniola, Maria Cardone, Matteo Velenosi, Donato Antonacci, Vittorio Alba, and Teodora Basile. "Study of the Influence of Different Yeast Strains on Red Wine Fermentation with NIR Spectroscopy and Principal Component Analysis." J 1, no. 1 (October 31, 2018): 133–47. http://dx.doi.org/10.3390/j1010013.

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Alcoholic fermentation is a key step in wine production. Indeed, a wide range of compounds, which strongly affect the sensory properties of wine, is produced during this process. While Saccharomyces cerevisiae yeast cultures are commonly employed in winemaking to carry on the fermentation process, some non-Saccharomyces species have recently gained attention due to their ability to produce various metabolites of oenological interest. The use of different yeasts strains usually results in wines with different sensory properties, despite being obtained from the same grape variety. In this paper, we tested the feasibility of using near-infrared spectroscopy (NIR) to discriminate among red wines from three different grape varieties produced with pure S. cerevisiae or by mixed fermentation with a promising non-Saccharomyces yeast, namely the Starmeriella bacillaris, which usually yields wines with significant amounts of glycerol and low levels of ethanol, acetic acid, and acetaldehyde. A principal component analysis (PCA) performed on the NIR spectra was used to search for differences in the samples. The NIR results have been compared with both basic wine parameters and sensory analysis data.
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46

Khawaja, N., F. Postberg, J. Hillier, F. Klenner, S. Kempf, L. Nölle, R. Reviol, Z. Zou, and R. Srama. "Low-mass nitrogen-, oxygen-bearing, and aromatic compounds in Enceladean ice grains." Monthly Notices of the Royal Astronomical Society 489, no. 4 (October 2, 2019): 5231–43. http://dx.doi.org/10.1093/mnras/stz2280.

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ABSTRACT Saturn’s moon Enceladus is erupting a plume of gas and ice grains from its south pole. Linked directly to the moon’s subsurface global ocean, plume material travels through cracks in the icy crust and is ejected into space. The subsurface ocean is believed to be in contact with the rocky core, with ongoing hydrothermal activity present. The Cassini spacecraft’s Ion and Neutral Mass Spectrometer (INMS) detected volatile, gas phase, organic species in the plume and the Cosmic Dust Analyser (CDA) discovered high-mass, complex organic material in a small fraction of ice grains. Here, we present a broader compositional analysis of CDA mass spectra from organic-bearing ice grains. Through analogue experiments, we find spectral characteristics attributable to low-mass organic compounds in the Enceladean ice grains: nitrogen-bearing, oxygen-bearing, and aromatic. By comparison with INMS results, we identify low-mass amines [particularly (di)methylamine and/or ethylamine] and carbonyls (with acetic acid and/or acetaldehyde most suitable) as the best candidates for the N- and O-bearing compounds, respectively. Inferred organic concentrations in individual ice particles vary but may reach tens of mmol levels. The low-mass nitrogen- and oxygen-bearing compounds are dissolved in the ocean, evaporating efficiently at its surface and entering the ice grains via vapour adsorption. The potentially partially water soluble, low-mass aromatic compounds may alternatively enter ice grains via aerosolization. These amines, carbonyls, and aromatic compounds could be ideal precursors for mineral-catalysed Friedel–Crafts hydrothermal synthesis of biologically relevant organic compounds in the warm depths of Enceladus’ ocean.
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47

Li, Guihua, Yonghui Zhao, Jerry Pui Ho Li, Wei Chen, Shoujie Li, Xiao Dong, Yanfang Song, Yong Yang, Wei Wei, and Yuhan Sun. "Insight into Composition and Intermediate Evolutions of Copper-Based Catalysts during Gas-Phase CO2 Electroreduction to Multicarbon Oxygenates." Catalysts 11, no. 12 (December 10, 2021): 1502. http://dx.doi.org/10.3390/catal11121502.

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Conversion of CO2 to valuable chemicals driven by renewable electricity via electrocatalytic reduction processes is of great significance for achieving carbon neutrality. Copper-based materials distinguish themselves from other electrocatalysts for their unique capability to produce multicarbon compounds in CO2 electroreduction. However, the intrinsic active composition and C–C coupling mechanism of copper-based catalysts are still ambiguous. This is largely due to the absence of appropriate in situ approaches to monitor the complicated processes of CO2 electroreduction. Here, we adopted operando spectroscopy techniques, including Raman and infrared, to investigate the evolution of compositions and intermediates during gas-phase CO2 electroreduction on Cu foam, Cu2O nanowire and CuO nanowire catalysts. Although all the three copper-based catalysts possessed the activity of electroreducing gas-phase CO2 to multicarbon oxygenates, Cu2O nanowires showed the much superior performance with a 71.9% Faradaic efficiency of acetaldehyde. Operando Raman spectra manifested that the cuprous oxide remained stable during the whole gas-phase CO2 electroreduction, and operando diffuse reflectance infrared Fourier transform spectroscopy (DRFITS) results provide direct evidences of key intermediates and their evolutions for producing multicarbon oxygenates, in consistence with the density functional theory calculations.
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48

Brei, Volodymyr. "OXIDATION OF ALCOHOLS OVER CERIUM-OXIDE CATALYST: CORRELATION BETWEEN THE ACTIVATION ENERGY OF THE REACTION AND THE CHEMICAL SHIFT δ (R13 COH)." Ukrainian Chemistry Journal 85, no. 8 (August 15, 2019): 66–72. http://dx.doi.org/10.33609/0041-6045.85.8.2019.66-72.

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The oxidation of thirteen alcohols over sup-ported CeO2/Al2O3 catalyst with 10 wt.% of CeO2 have been studied using a desorption mass-spec-trometry technique. A catalyst sample 4–6 mg in quartz cuvette was evacuated at 100 0C, cooled to room temperature, and then adsorption of a alco-hol was provided. After vacuumation of alcohol excess, the TPR profiles of products of alcohol oxidation were recorded at sweep rate 2 a.u.m./sec and heating rate of 15 0C/min using MX-7304A monopole mass- spectrometer. Identification of formed aldehydes and ketones was provided on the bases of their characteristic ions in obtained mass-spectra, namely, acetaldehyde (m/e = 29, 44); pro-panal (29, 58); acetone (43, 58); butanal (44, 43); methyl propanal (43, 41, 72), 2-butanon (43, 72); methoxyacetone (45, 43); cyclohexanone (55); ace-tophenone (105, 77); benzaldehyde (77, 106). It was shown that the oxidation of several alcohols pro-ceeds in a wide temperature interval from 130 to 280 0C. So, peak of formaldehyde formation from me-thanol adsorbed on CeO2/Al2O3 is observed at 280 0C whereas peaks of methyl glyoxal and water formation from adsorbed hydroxyacetone are re-corded at 135 0 C. The linear correlation between activation energy of reaction and chemical shift δ (R13COH) of studied alcohols was found as Ea= 183 –1.4δ (kJ/mol). Respectively, the maximum oxi-dation rate, for instance, for methanol (50 ppm) is observed at 280 0C, for ethanol (58 ppm) at 215 0C, for n-butanol (62 ppm) at 200 0C, for n-propanol (64 ppm) at 190 0C, for 2-butanol (69 ppm) at 160 0C, for hydroxyacetone (69 ppm) at 135 0C, and for 1-phenylethanol (70 ppm) at 130 0C. Thus, ability of alcohols to oxidation decreases with increase of their electronic density on carbon atom of alcohol group in following order: 1-phenyl ethanol ≈ hyd-roxyacetone ≈ cyclohexanol > allyl alcohol ≈ 2-bu-anol ≈ i-butanol ≈ i-propanol > methoxypropanol-2 ≈ n-propanol ≈ n-butanol ≈ benzyl alcohol ≈ ethanol >> methanol. On an example of ethanol, the scheme of alcohol oxidation on ceria that assumes the addition of atomic oxygen to C–H bond of alcoho-lic group with intermediate acetaldehyde hydrate formation is discussed.
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49

Manigand, S., J. K. Jørgensen, H. Calcutt, H. S. P. Müller, N. F. W. Ligterink, A. Coutens, M. N. Drozdovskaya, E. F. van Dishoeck, and S. F. Wampfler. "The ALMA-PILS survey: inventory of complex organic molecules towards IRAS 16293–2422 A." Astronomy & Astrophysics 635 (March 2020): A48. http://dx.doi.org/10.1051/0004-6361/201936299.

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Context. Complex organic molecules are detected in many sources in the warm inner regions of envelopes surrounding deeply embedded protostars. Exactly how these species form remains an open question. Aims. This study aims to constrain the formation of complex organic molecules through comparisons of their abundances towards the Class 0 protostellar binary IRAS 16293–2422. Methods. We utilised observations from the ALMA Protostellar Interferometric Line Survey of IRAS 16293–2422. The species identification and the rotational temperature and column density estimation were derived by fitting the extracted spectra towards IRAS 16293–2422 A and IRAS 16293–2422 B with synthetic spectra. The majority of the work in this paper pertains to the analysis of IRAS 16293–2422 A for a comparison with the results from the other binary component, which have already been published. Results. We detect 15 different complex species, as well as 16 isotopologues towards the most luminous companion protostar IRAS 16293–2422 A. Tentative detections of an additional 11 isotopologues are reported. We also searched for and report on the first detections of methoxymethanol (CH3OCH2OH) and trans-ethyl methyl ether (t-C2H5OCH3) towards IRAS 16293–2422 B and the follow-up detection of deuterated isotopologues of acetaldehyde (CH2DCHO and CH3CDO). Twenty-four lines of doubly-deuterated methanol (CHD2OH) are also identified. Conclusions. The comparison between the two protostars of the binary system shows significant differences in abundance for some of the species, which are partially correlated to their spatial distribution. The spatial distribution is consistent with the sublimation temperature of the species; those with higher expected sublimation temperatures are located in the most compact region of the hot corino towards IRAS 16293–2422 A. This spatial differentiation is not resolved in IRAS 16293–2422 B and will require observations at a higher angular resolution. In parallel, the list of identified CHD2OH lines shows the need of accurate spectroscopic data including their line strength.
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50

Ruuskanen, T. M., M. Müller, R. Schnitzhofer, T. Karl, M. Graus, I. Bamberger, L. Hörtnagl, F. Brilli, G. Wohlfahrt, and A. Hansel. "Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF." Atmospheric Chemistry and Physics Discussions 10, no. 9 (September 2, 2010): 21077–108. http://dx.doi.org/10.5194/acpd-10-21077-2010.

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Abstract. Eddy covariance (EC) is the preferable technique for flux measurements since it is the only direct flux determination method. It requires a continuum of high time resolution measurements (e.g. 5–20 Hz). For volatile organic compounds (VOC) soft ionization via proton transfer reaction has proven to be a quantitative method for real time mass spectrometry; here we use a proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution of the PTR-TOF enabled the identification of chemical formulas and separation of oxygenated and hydrocarbon species exhibiting the same nominal mass. We determined 481 ion mass peaks from ambient air concentration above a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria. During harvesting we found significant fluxes of 18 compounds distributed over 43 ions, including protonated parent compounds, as well as their isotopes and fragments and VOC-H+-water clusters. The dominant BVOC fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes. The smallest reliable fluxes we determined were less than 0.1 nmol m−2 s−1, as in the case of sesquiterpene emissions from freshly cut grass. Terpenoids, including mono- and sesquiterpenes, were also deposited to the grassland before and after the harvesting. During cutting, total VOC emission fluxes up to 200 nmol C m−2 s−1 were measured. Methanol emissions accounted for half of the emissions of oxygenated VOCs and a third of the carbon of all measured VOC emissions during harvesting.
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