Search results for "Atmospheric Pressure"
showing 10 items of 105 documents
Accurate spectroscopic constants of nitrogen determined from stimulated Raman spectra of the fundamental and first hot bands
1990
Nitrogen spectra of the Q-branch of the fundamental and the first hot bands were recorde with a high-resolution stimulated Raman spectrometer at atmospheric pressure and ca. 1300 K. The absolute frequencies of the Raman lines were measured with high accuracy, leading to a refinement of spectroscopic constants. A temperature estimation was also performed from the Raman intensities.
ChemInform Abstract: Catalytic Activity of Large-Pore High Si/Al Zeolites: Cracking of Heptane on H-Beta and Dealuminated HY Zeolites
1988
Abstract The catalytic activity, selectivity, catalyst decay, thermal and hydrothermal stability, and acidity of H-Beta and HY zeolites with Si Al ratios of 7.5 and 10, respectively, have been studied during cracking of n-heptane at 450 °C and atmospheric pressure. It has been found that the H-Beta zeolite is more active and decays more slowly than HY. H-Beta presents a higher steric hindrance for dibranched molecules and therefore its open structure should be smaller than that of HY. A lower hydrogen transfer activity and hydrothermal stability is observed for H-Beta in comparison with the corresponding HY.
A device to trigger automatically electrical stimulation at different states of in- or expiration on the background of variable lung inflation in the…
1975
A device is described which permits to obtain a signal at the beginning of in- or expiration respectively. This signal may be used to trigger an electrical stimulator. To permit studies at different states of lung inflation the tracheal cannula is connected to a spirometer circuit. To produce constant positive or negative air pressure this bellows-type spirometer is loaded with exchangeable metal weights. The tracheal pressure is recorded by means of a pressure transducer, the output of which is taken as signal. The device allows accurate compensation of the DC-component of the transducer output resulting from spirometer operation at a maintained positive or negative pressure.
A study on the fragmentation of sulfuric acid and dimethylamine clusters inside an Atmospheric Pressure interface Time Of Flight Mass Spectrometer
2021
Abstract. Sulfuric acid and dimethylamine vapours in the atmosphere can form molecular clusters, which participate in new particle formation events. In this work, we have produced, measured and identified clusters of sulfuric acid and dimethylamine using an electrospray ionizer coupled with a planar differential mobility analyser, connected to an atmospheric pressure interface time-of-flight mass spectrometer (ESI–DMA–APi-TOF MS). This set-up is suitable for evaluating the extent of fragmentation of the charged clusters inside the instrument. We evaluated the fragmentation of 11 negatively charged clusters both experimentally and using a statistical model based on quantum chemical data. The…
Separation of the azeotropic mixture 2-propanol + water employing different imidazolium ionic liquids as solvents
2020
Abstract The liquid-liquid equilibria of the ternary systems water (1) + 2-propanol (2) + [emim][Tf2N] (3) and water (1) + 2-propanol (2) + [hmim][Tf2N] (3) at 283.2, 303.2 and 323.2 K and atmospheric pressure were investigated, in order to achieve a better knowledge of the ternary mixture behaviour. The capability of [emim][Tf2N] and [hmim][Tf2N] as solvents in the separation of the azeotropic mixture water + 2-propanol was studied through the distribution coefficient and selectivity, and compared with the results obtained with other ionic liquids in the same azeotropic mixture studied before by our research group. The thermodynamic parameters of both ternary mixtures were calculated by th…
In vivo aroma release by APCI-MS and PTR-MS: impact of water content of exhaled air and evidence for competition between aroma compounds
2013
Livre ISBN-13 : 978-3-902811-91-2; International audience; Atmospheric pressure chemical ionization mass spectrometry (APCI-MS) or proton transfer reaction mass spectrometry (PTR-MS) has been in use frequently for in vivo aroma release studies. In APCI-MS, protonated water clusters formed from moisture in the expired air are used as reagent ions. Yet the influence of a change in relative water content in the ionization gas on the data collected have been rarely studied and conflicting results were obtained. In this context our first objective was to study the impact of water content of the expired air on the level of aroma release measured by APCI-MS and to compare with the results obtained…
Effect of pressure on the electrochemical generation of hydrogen peroxide in undivided cells on carbon felt electrodes
2017
The electrochemical generation of H2O2can be performed in aqueous solutions by cathodic reduction at carbonaceous cathodes of oxygen coming from air. The performances of the process in terms of concentration of H2O2and current efficiency (CE) are limited by the low solubility of oxygen in water at atmospheric pressure. However, the solubility of oxygen can be increased upon enhancing the air pressure. The effect of pressure on the electrochemical generation of hydrogen peroxide was studied in undivided cells changing the pressure from 0 to 30 relative bar and the current density from 1 to 100Â mAÂ cmâ2. Simple carbon felt and compact graphite cathodes were first used. A dramatic effect of…
A new class of ZnIIand CrIIIporphyrins incorporated into porous polymer matrices via an atmospheric pressure plasma enhanced CVD to form gas sensing …
2014
Designed ZnII and CrIII porphyrins (ZnIIP, CrIIIP(Cl)(H2O)) and conventional ZnIITPP and CrIIITPP(Cl)(H2O) are immobilized into porous polysiloxane films via chemical vapor deposition enhanced by an atmospheric pressure dielectric barrier discharge. UV/vis spectroscopy and mass spectrometry prove the integrity of the chromophores after the plasma treatment. The optical amine sensing capabilities of the films are investigated spectroscopically on exposure to triethylamine vapors. A series of coatings with different porphyrin loadings indicate influences of the deposition conditions on the growth of the sensing films and hence the device performance. Additionally, the synthesis and characteri…
A fast method for determining low-molecular-mass aliphatic carboxylic acids by high-performance liquid chromatography–atmospheric pressure chemical i…
2006
A fast quantitative high-performance liquid chromatographic separation method with atmospheric pressure chemical ionization mass spectrometric detection (HPLC-APCI-MS) was developed for the determination of low-molecular-mass aliphatic mono- and dicarboxylic acids typically present in different industrial process waters. A mixture of glycolic, lactic, a-glucoisosaccharinic, oxalic, maleic, fumaric, succinic, malic, glutaric, methylsuccinic, and adipic acids was separated using an RP chromatographic system. Adipic acid was used as an internal standard to calculate correlation coefficients for the acids studied. The chromatographic analysis of these acids was primarily carried out by means of…
Eine oligomeranaloge friessche umlagerung oligomerer 2-acetoxy-1,3-phenylenmethylene
1979
α-Hydro-ω-hydroxypoly(5-chloro-2-hydroxy-1,3-phenylenemethylene)s (1a, b), the oligomeric condensation products from 4-chloro-2,6-bis(hydroxymethyl)phenol and 4-chlorophenol with hydrochloric acid in 1,4-dioxane, could be completely dehalogenated at room temperature and atmospheric pressure with hydrogene/Raney-Ni. The resulting oligomers 2a, b were esterified with acetic anhydride, and the esters 3a, b were subjected to a oligomer analogous Fries rearrangement to form the linear α-hydro-ω-hydroxypoly(5-acetyl-2-hydroxy-1,3-phenylenemethylene)s 4a and 4b. The characterization of the products was mainly done by spectroscopic methods.