New Insight into the Gas-Phase Bimolecular Self-Reaction of the HOO Radical

2007 ◽  
Vol 111 (9) ◽  
pp. 1695-1704 ◽  
Author(s):  
Josep M. Anglada ◽  
Santiago Olivella ◽  
Albert Solé
Keyword(s):  
Gas Phase ◽  
Insight Into

An insight into the gas-phase inhibition mechanism of polymers by addition of triphenyl phosphate flame retardant

2020 ◽  
Author(s):  
S. A. Trubachev ◽  
O. P. Korobeinichev ◽  
S. A. Kostritsa ◽  
V. D. Kobtsev ◽  
A. A. Paletsky ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Gas Phase ◽  
Inhibition Mechanism ◽  
Triphenyl Phosphate ◽  
Insight Into

Theoretical insight into the substituent effects on the antioxidant properties of 8-hydroxyquinoline derivatives in gas phase and in polar solvents

2018 ◽  
Vol 96 (5) ◽  
pp. 453-458
Author(s):  
Anes El-Hadj Saïd ◽  
Sidi Mohamed Mekelleche ◽  
Taki-Eddine Ahmed Ardjani
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
Antioxidant Properties ◽  
Substituent Effects ◽  
Hydrogen Atom Transfer ◽  
Polar Solvents ◽  
Antioxidant Power ◽  
Theoretical Insight ◽  
Insight Into

The objective of this work is to perform a theoretical analysis of the antioxidant properties of a series of 8-hydroxyquinolines (8-HQs) to rationalize the available experimental results and to design new potent 8-HQ derivatives. The study was carried out in gas phase and in methanol at the DFT/B3LYP/ 6-311++G(d,p) computational level. The formation of stable ArO• radicals is discussed on the basis of different mechanisms, namely, hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and single proton loss electron transfer (SPLET). The obtained results show that the HAT mechanism is, thermodynamically, more favoured in gas phase, whereas the SPLET pathway is more favoured in polar solvents. The calculated thermochemical descriptors allow classification of the antioxidant power of the studied compounds.

Key Mechanistic Insight into the Direct Gas-Phase Epoxidation of Propylene by the RuO2-CuO-NaCl/SiO2Catalyst

ChemCatChem ◽  
2014 ◽  
pp. n/a-n/a ◽  
Author(s):  
Anusorn Seubsai ◽  
Bahman Zohour ◽  
Daniel Noon ◽  
Selim Senkan
Keyword(s):  
Gas Phase ◽  
Epoxidation Of Propylene ◽  
Mechanistic Insight ◽  
Insight Into

Spectroscopic Determination of C2 Densities in AR/H 2/CH 4 and AR/H2/C60 Microwave Plasmas For Nanocrystalline Diamond Synthesis

1997 ◽  
Vol 502 ◽  
Author(s):  
A. N. Goyette ◽  
J. E. Lawler ◽  
L. W. Anderson ◽  
D. M. Gruen ◽  
T. G. Mccauley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Diamond Films ◽  
High Sensitivity ◽  
Nanocrystalline Diamond ◽  
Chamber Pressure ◽  
Diamond Synthesis ◽  
Microwave Plasmas ◽  
State Concentration ◽  
Insight Into

ABSTRACTWe have measured the steady state concentration of gas phase C2 in Ar/H2/CH4 and Ar/H2/C60 microwave plasmas used for the deposition of nanocrystalline diamond films. High sensitivity white light absorption spectroscopy is used to monitor the C2 density using the d 3 Π ← a3Π (0,0) vibrational band of C2 as chamber pressure, microwave power, substrate temperature and feed gas mixtures are varied in both chemistries. Understanding how these parameters influence the C2 density in the plasma volume provides insight into discharge mechanisms relevant to the deposition of nanocrystalline diamond.

Conceptual Examination of Gas Phase Particulate Formation in Gas Turbine Combustors

1980 ◽  
Vol 102 (3) ◽  
pp. 613-618 ◽  
Author(s):  
A. S. Kesten ◽  
J. J. Sangiovanni ◽  
P. Goldberg
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Mathematical Framework ◽  
Droplet Combustion ◽  
Laboratory Studies ◽  
Gas Turbine Combustors ◽  
Large Particles ◽  
Fuel Pyrolysis ◽  
Insight Into ◽  
Recent Laboratory

Recent laboratory studies of droplet combustion indicate the potential for substantial gas phase particulate formation even with single component hydrocarbon fuels. Formation of large particles has been observed in the neighborhood of burning droplet arrays, particularly when the droplets are closely spaced. To provide insight into the potential for particulate formation during the combustion of fuel droplet sprays in gas turbine combustors, a mathematical framework is developed for examining the formation of soot nuclei in droplet combustion. A simplified model of the chemistry of fuel pyrolysis and nuclei formation is used and a series of calculations is made to explore the sensitivity of soot nuclei formation to conditions typical of gas turbine combustion systems.

scholarly journals Unravelling the Keto-Enol Tautomer Dependent Photochemistry and Degradation Pathways of the Protonated UVA Filter Avobenzone

2020 ◽  
Author(s):  
Jacob A. Berenbeim ◽  
Natalie Wong ◽  
Martin C. R. Cockett ◽  
Giel Berden ◽  
Jos Oomens ◽  
...  
Keyword(s):  
Gas Phase ◽  
Free Electron Laser ◽  
Selective Excitation ◽  
Uv Laser ◽  
Infrared Multiple Photon Dissociation ◽  
Enol Tautomer ◽  
Ion Yields ◽  
The Stability ◽  
First Time ◽  
Insight Into

Avobenzone (AB) is a widely used UVA filter known to undergo irreversible photodegradation. Here, we investigate the detailed pathways by which AB photodegrades by applying UV laser-interfaced mass spectrometry to protonated AB ions. Gas-phase infrared multiple-photon dissociation (IRMPD) spectra obtained with the free electron laser for infrared experiments, FELIX, (600-1800 cm-1) are also presented to confirm the geometric structures. The UV gas-phase absorption spectrum (2.5-5 eV) of protonated AB contains bands that correspond to selective excitation of either the enol or diketo forms, allowing us to probe the resulting, tautomer-dependent photochemistry. Numerous photofragments (i.e. photodegradants) are directly identified for the first time, with m/z 135 and 161 dominating, and m/z 146 and 177 also appearing prominently. Analysis of the production spectra of these photofragments reveals that that strong enol to keto photoisomerism is occurring, and that protonation significantly disrupts the stability of the enol (UVA active) tautomer. Close comparison of fragment ion yields with the TDDFT-calculated absorption spectra give detailed information on the location and identity of the dissociative excited state surfaces, and thus provide new insight into the photodegradation pathways of avobenzone, and photoisomerisation of the wider class of β-diketone containing molecules.<br>

scholarly journals Linkage Memory in Underivatized Protonated Carbohydrates

2020 ◽  
Author(s):  
Abhigya Mookherjee ◽  
Sanjit S. Uppal ◽  
Taylor A. Murphree ◽  
Miklos Guttman
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Large Scale ◽  
Biological Function ◽  
Hydrogen Deuterium Exchange ◽  
Fragment Ions ◽  
Hydrogen Deuterium ◽  
Structural Insight ◽  
Multiple Conformations ◽  
Insight Into

<p>Carbohydrates are among the most complex class of biomolecules and even subtle variations in their structures are attributed to diverse biological function. Mass spectrometry has been essential for large scale glycomics and glycoproteomics studies, but the gas-phase structures and sometimes anomalous fragmentation properties of carbohydrates present longstanding challenges. Here we investigate the gas-phase properties of a panel of isomeric protonated disaccharides differing in their linkage configurations. Multiple conformations were evident for most of the structures based on their fragment ion abundances by tandem mass spectrometry, their ion mobilities in several gases, and their deuterium uptake kinetics by gas-phase hydrogen deuterium exchange. Most notably, we find that the properties of the Y-ion fragments are characteristically influenced by the precursor carbohydrate’s linkage configuration. This study reveals how protonated carbohydrate fragment ions can retain ‘linkage memory’ that provides structural insight into their intact precursor.</p>

scholarly journals Latvijas minerālās izejvielas eko-keramikas izstrādei

2018 ◽  
Vol 35 ◽  
pp. 62-85
Author(s):  
Gaida Sedmale ◽  
Māris Rundāns ◽  
Mārtiņs Randers ◽  
Ingunda Šperberga ◽  
Andris Cimmers
Keyword(s):  
High Temperature ◽  
Ceramic Material ◽  
Gas Phase ◽  
Phase Formation ◽  
Raw Materials ◽  
Ceramic Materials ◽  
Firing Process ◽  
Mineral Raw Materials ◽  
Technological Processes ◽  
Insight Into

Darbā dots ieskats par iespējām izmantot Latvijas minerālās izejvielas kā bāzi vai  piedevu  keramikas  materiālu  (eko-materiālu)  izstrādei ar dažādu pielietošanas aspektu, to skaitā parādīt iespēju šo materiālu ieguves tehnoloģisko procesu optimizēšanai virzībā uz to apdedzināšanas temperatūras samazināšanu, līdz ar to reducējot kaitīgu gāzveida izmešu nonākšanu vidē. Parādīti darbu rezultāti laika periodā no 2007. g. līdz 2017. g. Tiek apskatīti un analizēti sekojoši pētījumi:neapstrādāta māla pielietošana atkritumu deponēšanas vietu noblīvēšanai;daļēji dehidratizēta māla pielietošana Cr3+, Cr6+, Zn2+ un Cu+ jonu sorbcijai, kas veidojas galvanisko procesu notekūdeņos; poru saturošas augsttemperatūras keramikas izstrāde no jauktiem izejvielu maisījumiem, kas nodrošina pietiekamu gāzveida fāzes izveidošanos keramikas apdedzināšanas procesā, veidojot poras, lai pielietotu par filtrēšanas/attīrīšanas materiālu;illīta māla piedevu izmantošana, lai pazeminātu augsttemperatūras blīvas keramikas saķepināšanas/apdedzināšanas temperatūru, iegūstot ilgspējīgu mehāniski un termiski izturīgu produktu; kā arī tehnoloģiskie procesi, kas nodrošina porainas, siltumu izolējošas keramikas materiāla ieguvi pie pazeminātām temperatūrām (ģeopolimēru metode).Mineral Raw Materials of Latvia for Development of Eco-CeramicsThe paper gives an insight into the possibilities to use Latvian mineral raw materials as a base or additives for the development of ceramic materials (eco- materials) with different application aspects, including showing the possibility of optimizing the technological processes of these materials towards the reduction of their firing temperature, thereby reducing the release of harmful gaseous effluents into the environment.The results of the works that are reported in the period were obtained from  2007 to 2017. The following studies are reviewed and analyzed: the use of untreated clay for the sealing of waste deposits; the use of partly dehydrated clay for sorption of Cr3+,6+, Zn2+ and Cu2+, which have formed in galvanic processes; the development of porous high temperature ceramics from mixes  of mineral raw materials and synthetic additives that provide a sufficient gas phase  formation in the firing process and consecutively to form pores in obtained ceramic material; the use of illite clay additives to reduce the temperature of sintering of high temperature dense mechanical and thermally durable ceramics, as well as technological processes that ensure the production of porous, heat-insulating ceramic materials at reduced temperatures (geopolymer method).

scholarly journals ANTIOXIDANT PROPERTIES OF FOLIC ACID: A DFT STUDY

2018 ◽  
Vol 56 (4A) ◽  
pp. 39 ◽  
Author(s):  
Dao Duy Quang
Keyword(s):  
Free Radicals ◽  
Folic Acid ◽  
Gas Phase ◽  
Antioxidant Properties ◽  
Hydrogen Atom Transfer ◽  
Single Electron Transfer ◽  
To Receive ◽  
Antioxidant Mechanisms ◽  
Insight Into ◽  
Free Radicals Scavenging

Antioxidant activity of folic acid (FA) was investigated via two main antioxidant mechanisms: hydrogen atom transfer (HAT) and single electron transfer (SET) at the DFT/B3LYP/6-311G(d,p) level of theory. The characterizing thermochemical properties such as bond dissociation enthalpies (BDEs), ionization energy (IE) and electron affinity (EA) were calculated in the gas phase. Analyses of HOMOs distribution shows that the postions which easily donate electrons to free radicals are essentially found at C ring, while the positions which easily accept electrons (LUMOs) from radicals are mainly situated at B ring. The lowest BDE values equal to 76.5 and 80.1 kcal/mol are obtained at C19-H and C9–H position, respectively. It is showed that FA represents a potential antioxidant via HAT mechanism. In addition, the IE and EA values calculated in the gas phase are equal to 5.45 eV and 1.87 eV, respectively. This result shows that FA has higher ability to donate electrons into free radicals, while the ability to receive electrons is quite weak. Finally, the HAT reaction between FA and reactive radical like HOO• was also calculated at the same level of theory. This provides more insight into its mechanism on free radicals scavenging.

Sign in / Sign up

Export Citation Format

Share Document