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The rates of nucleation of liquid aerosols from the gaseous mixtures H2SO4 + H2O and HNO3 + H2O at 25°C for various relative humidities (10 to 100%) and various activities of acid vapor are calculated using the Flood-Neumann-Döring-Reiss-Doyle theory of binary homogeneous nucleation. The activities of acid vapor needed for nucleation are 25 to 300 times smaller for H2SO4 + H2O than for HNO3 + H2O. This is due to the much larger free energy of mixing in the liquid phase for H2SO4 + H2O. Conversion from activities to actual pressures leads to concentrations of HNO3 which are much too high to be found under normal atmospheric conditions. On the other hand, the concentrations of H2SO4 vapor needed to nucleate droplets in the H2SO4 + H2O system are in the range 4(10?5) to 1.3 (10?2) ppm, a concentration which can result from photo-oxidation of SO2 in the atmosphere. Calculations are made of the growth curves for H2SO4 + H2O droplets (radius vs composition) at various relative humidities from the critical size radius up to a 1000 Å radius, corresponding to nuclei large enough to serve as condensation centers for heterogeneous nucleation. The limitations of binary homogeneous nucleation theory at extremely low concentrations of one of the components are discussed and it is shown that this theory becomes inapplicable if the actual vapor pressure of one component is below 10?6 torr. 相似文献
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Rapid fractionation of grape seed proanthocyanidins. 总被引：5，自引：0，他引：5
C Saucier M Mirabel F Daviaud A Longieras Y Glories 《Journal of agricultural and food chemistry》2001,49(12):5732-5735
A rapid method that permits separation of grape seed proanthocyanidins according to their polymerization degrees has been developed. This method was based on liquid/liquid extraction and relative solubility of these compounds in different solvents (water, ethyle acetate, methanol, and chloroform). The different fractions obtained were then analyzed by various HPLC techniques (normal phase, reversed phase after thiolysis, and gel permeation) to determine their mean degree of polymerization (DP) and molecular weight profiles. Results show that this method can be used on a preparative scale to separate these polymers according to their sizes. 相似文献
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Mirabel IF 《Science (New York, N.Y.)》2012,335(6065):175-176
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Millet Maurice Wortham Henri Mirabel Philippe Flori Jean-Paul Lakkis Dominique Leroy Maurice 《Water, air, and soil pollution》2001,132(1-2):105-126
In the present study, included within the framework of a Franco-German Research Program for Conservation of HistoricalMonuments, the chemical composition of rainwater was investigated in Thann (Alsace, France) and in Tours (Indre etLoire, France) between 1992 and 1993. A total of 78 and 24samples, respectively, were collected, near the Thann collegiateand the Tours cathedral on a weekly basis and analysed for Cl-, NO3 -, SO4 2-, Na+, NH4 +, K+, Mg2+ and Ca2+. Results showpH ranged from 3.60 to 6.58 and from 5.49 to 7.01 for Thann andTours, respectively. In Thann, SO4 2- is the major anion and rainwater acidity is neutralised by compounds ofterrigenic origin which come from the soil of the upper Rhinevalley (Ca2+; ‘loess’) and the potash mines of Alsace. In Tours, SO4 2- is also the major anion and the acidity is neutralised partially by atmospheric ammonia and partially by compounds of terrigenic origin and by dust fromthe erosion of the cathedral and the works of restoration, in the form of CaCO3. 相似文献
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Mazzali PA Valenti S Della Valle M Chincarini G Sauer DN Benetti S Pian E Piran T D'Elia V Elias-Rosa N Margutti R Pasotti F Antonelli LA Bufano F Campana S Cappellaro E Covino S D'Avanzo P Fiore F Fugazza D Gilmozzi R Hunter D Maguire K Maiorano E Marziani P Masetti N Mirabel F Navasardyan H Nomoto K Palazzi E Pastorello A Panagia N Pellizza LJ Sari R Smartt S Tagliaferri G Tanaka M Taubenberger S Tominaga N Trundle C Turatto M 《Science (New York, N.Y.)》2008,321(5893):1185-1188
The only supernovae (SNe) to show gamma-ray bursts (GRBs) or early x-ray emission thus far are overenergetic, broad-lined type Ic SNe (hypernovae, HNe). Recently, SN 2008D has shown several unusual features: (i) weak x-ray flash (XRF), (ii) an early, narrow optical peak, (iii) disappearance of the broad lines typical of SN Ic HNe, and (iv) development of helium lines as in SNe Ib. Detailed analysis shows that SN 2008D was not a normal supernova: Its explosion energy (E approximately 6x10(51) erg) and ejected mass [ approximately 7 times the mass of the Sun (M(middle dot in circle))] are intermediate between normal SNe Ibc and HNe. We conclude that SN 2008D was originally a approximately 30 M(middle dot in circle) star. When it collapsed, a black hole formed and a weak, mildly relativistic jet was produced, which caused the XRF. SN 2008D is probably among the weakest explosions that produce relativistic jets. Inner engine activity appears to be present whenever massive stars collapse to black holes. 相似文献
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In the frame of the climatological project REKLIPwhich involves part of Switzerland, Germany and Franceand concerns the upper Rhine valley, an atmosphericemission inventory has been established with a spatialresolution of a square kilometer and a time resolutionup to one hour. Anthropogenic emissions of SO2, NOx,CO, HCl and volatile organic compounds (VOC) divided into thirty compounds or group of compounds as well as biogenic emissions of NMVOC have been taken into account for the year 1990. This inventory has been updated for the following years until 1993 and some hourly emissions inventories have been derived for a period of several days of September 1992,corresponding to a REKLIP intensive measurement campaign. 相似文献
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We show that the black hole in the x-ray binary Cygnus X-1 was formed in situ and did not receive an energetic trigger from a nearby supernova. The progenitor of the black hole had an initial mass greater than 40 solar masses, and during the collapse to form the approximately 10-solar mass black hole of Cygnus X-1, the upper limit for the mass that could have been suddenly ejected is approximately 1 solar mass, much less than the mass ejected in a supernova. The observations suggest that high-mass stellar black holes may form promptly, when massive stars disappear silently. 相似文献
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