We report the first use of synchrotron radiation, continuously tunable from 8 to 15 eV, for flame-sampling photoionization mass spectrometry (PIMS). Synchrotron radiation offers important advantages over the use of pulsed vacuum ultraviolet lasers for PIMS; these include superior signal-to-noise, soft ionization, and access to photon energies outside the limited tuning ranges of current VUV laser sources. Near-threshold photoionization efficiency measurements were used to determine the absolute concentrations of the allene and propyne isomers of C3H4 in low-pressure laminar ethylene–oxygen and benzene–oxygen flames. Similar measurements of the isomeric composition of C2H4O species in a fuel-rich ethylene–oxygen flame revealed the presence of substantial concentrations of ethenol (vinyl alcohol) and acetaldehyde. Ethenol has not been previously detected in hydrocarbon flames. Absolute photoionization cross sections were measured for ethylene, allene, propyne, and acetaldehyde, using propene as a calibration standard. PIE curves are presented for several additional reaction intermediates prominent in hydrocarbon flames.

Selective detection of isomers with photoionization mass spectrometry for studies of hydrocarbon flame chemistry

The photo-assisted catalytic degradation of ethylene was studied in the tubular photoreactor packed with TiO2 pellets prepared by sol–gel method. The dependence of the reaction rate on the light intensity, feed composition (ethylene, oxygen and water vapor) and temperature were investigated. More than 95% ethylene was always completely mineralized irrespective of the reaction conditions. The reaction rate for ethylene conversion was greatly suppressed when the water vapor mole fraction was increased in the reactant gas stream. The rate determining step is the oxidation of C2H4OH radicals with oxygen on the catalyst surface. The rate law is expressed as follows to account for the results obtained: − d [ C 2 H 4 ] d t = k 9 K 8 I a φK C 2 H 4 P C 2 H 4 K O 2 P O 2 k OH (1+K C 2 H 4 P C 2 H 4 +K H 2 O P H 2 O )(1+K O 2 P O 2 )

Kinetic studies of oxidation of ethylene over a TiO2 photocatalyst

Photocatalytic degradation of trichloroethylene in water using TiO2 pellets.

The rate coefficients of thermal decomposition of peroxyacetic nitric anhydride (PAN) and peroxymethacrylic nitric anhydride (MPAN) were measured over the temperature range 302–323 K. The resulting Arrhenius expressions were k = 1017.4±0.4 exp(−28.5 ± 0.5/RT) for PAN, and k = 1016.2±0.7 exp(−26.8 ± 1.0/RT) for MPAN, where the activation energy is in Kcal/mol. These results are in good agreement with previous studies of PAN and other PAN-type compounds, and imply that energies of RC(O)OONO2 bonds are relatively independent of the nature of R.

The thermal decomposition of peroxyacetic nitric anhydride (PAN) and peroxymethacrylic nitric anhydride (MPAN)

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Toxicological profile for tetrachloroethylene

The kinetics and product formation of the homogeneous gas-phase reactions of the OH radical with 1,1-di-, tri- and tetrachloroethylene were investigated at temperatures between 298–459 K, in the pressure range of 0.5–5.6 mbar. Measurements were made in a discharge-flow apparatus, using helium as the carrier gas. The OH radical and the reaction products were detected by mass spectrometry. The rate constants were observed to be pressure independent in the case of 1,1-di- and tetrachloroethylene but slightly pressure dependent in the case of trichloroethylene. The temperature dependencies can be expressed by the Arrhenius equation (in units of 1012 cm3 mol−1 s−1).



k(T) = (0.136 ± 0.016) exp[(9.5 ± 0.4) kJ mol−1/RT] for 1,1-dichloroethylene,



k(T) = (0.470 ± 0.051) exp[(2.0 ± 0.5) kJ mol−1/RT] for trichloroethylene, and



k(T) = (3.33 ± 0.19) exp[−(8.6 ± 0.1) kJ mol−1/RT] for tetrachloroethylene.



The major products are: CH2OH — CCl2 for 1,1-dichloroethylene; 2,2-dichloroethenol and Cl for trichloroethylene; trichloroethenol, dichloroacetyl chloride, Cl, CHCl2 and phosgene for tetrachloroethylene.

The Reaction of OH Radicals with 1,1‐di‐, tri‐ and tetrachloroethylene

Abstract: Background The close monitoring of blood pressure during a caesarean section performed under central neuraxial anaesthesia should be the standard of safe anaesthesia. As classical oscillometric and invasive blood pressure measuring have intrinsic disadvantages, we investigated a novel, non-invasive technique for continuous blood pressure measuring. Methods: In this monocentric, retrospective data analysis, the reliability of continuous non-invasive blood pressure measuring using ClearSight® (Edwards Lifesciences Corporation) is validated in 31 women undergoing central neuraxial anaesthesia for caesarean section. In addition, patients and professionals evaluated ClearSight® through questioning. Results: 139 measurements from 11 patients were included in the final analysis. Employing Bland–Altman analyses, we identified a bias of −10.8 mmHg for systolic, of −0.45 mmHg for diastolic and of +0.68 mmHg for mean arterial blood pressure measurements. Pooling all paired measurements resulted in a Pearson correlation coefficient of 0.7 for systolic, of 0.67 for diastolic and of 0.75 for mean arterial blood pressure. Compensating the interindividual differences in linear regressions of the paired measurements provided improved correlation coefficients of 0.73 for systolic, of 0.9 for diastolic and of 0.89 for mean arterial blood pressure measurements. Discussion: Diastolic and mean arterial blood pressure are within an acceptable range of deviation from the reference method, according to the Association for the Advancement of Medical Instrumentation (AAMI) in the patient collective under study. Both patients and professionals prefer ClearSight® to oscillometric blood pressure measurement in regard of comfort and handling.

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The Use of Non-Invasive Continuous Blood Pressure Measuring (ClearSight®) during Central Neuraxial Anaesthesia for Caesarean Section—A Retrospective Validation Study

D. Helf

Papers

The Reaction of OH Radicals with 1,1‐di‐, tri‐ and tetrachloroethylene

The Use of Non-Invasive Continuous Blood Pressure Measuring (ClearSight®) during Central Neuraxial Anaesthesia for Caesarean Section—A Retrospective Validation Study