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Search Results: 1 - 10 of 219595 matches for " C. Delval "
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The rate of water vapor evaporation from ice substrates in the presence of HCl and HBr: implications for the lifetime of atmospheric ice particles
C. Delval, B. Fluckiger,M. J. Rossi
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2003,
Abstract: Using a multidiagnostic approach the rate Rev [ molec cm-3 s-1] or flux Jev [ molec cm-2 s-1] of evaporation of H2O and its corresponding rate constant for condensation, kcond [s-1 ], on a 1 μm thick ice film have been studied in the temperature range 190 to 240 K as well as in the presence of small amounts of HCl and HBr that left the vapor pressure of H2O on ice unchanged. The resulting Arrhenius expressions for pure ice are Jev = 1.6 · 10 28 ± 1 · exp (- 10.3 ± 1.2/ RT) [ molec cm-2 s-1] , kcond = 1.7 · 10 - 2 ± 1 · exp (+ 1.6 ± 1.5/ RT ) [s -1], in the presence of a HCl mole fraction in the range 3.2 · 10 - 5 - 6.4 · 10 - 3 : Jev = 6.4 · 10 26 ± 1 · exp (- 9.7 ± 1.2/ RT) [ molec cm-2 s-1] , kcond = 2.8 · 10 - 2 ± 1 · exp ( + 1.5 ± 1.6 /RT) [s -1], and a HBr mole fraction smaller than 6.4 · 10 - 3 : Jev = 7.4 · 10 25 ± 1 · exp ( - 9.1 ± 1.2 /RT) [ molec cm-2 s-1] , kcond = 7.1 · 10 - 5 ± 1 · exp (+ 2.6 ± 1.5/ RT) [s -1]. The small negative activation energy for H2O condensation on ice points to a precursor mechanism. The corresponding enthalpy of sublimation is DHsubl = Eev - Econd = 11.9 ± 2.7 kcal mol-1 , DHsubl = 11.2 ± 2.8 kcal mol-1, and DHsubl = 11.7 ± 2.8 kcal mol-1 whose values are identical within experimental uncertainty to the accepted literature value of 12.3 kcal mol-1 . Interferometric data at 633 nm and FTIR absorption spectra in transmission support the kinetic results. The data are consistent with a significant lifetime enhancement for HCl- and HBr-contaminated ice particles by a factor of 3–6 and 10–20, respectively, for submonolayer coverages of HX once the fraction of the ice not contaminated by HX has evaporated.
The rate of water vapor evaporation from ice substrates in the presence of HCl and HBr: Implications for the lifetime of atmospheric ice particles
C. Delval,B. Fluckiger,M. J. Rossi
Atmospheric Chemistry and Physics Discussions , 2003,
Abstract: Using a multidiagnostic approach the rate Rev or flux Jevof evaporation of H2O and its condensation, kcond, on a 1mm thick ice film have been studied in the temperature range 190 to 240 K as well as in the presence of small amounts of HCl and HBr that left the vapor pressure of H2O on ice unchanged. The resulting Arrhenius expressions with RT in kcal mol-1 for pure ice are Jev=1.6×1028+/ 1·exp({ 10.3+ 1.2}/{RT}) [molec cm 2 s 1], kcond=1.7×10 2+-1×exp({+1.6+ 1.5}/{RT}) [s 1], in the presence of an HCl mole fraction in the range 3.2×10 5-6.4×10 3: Jev=6.4×1026+/ 1×exp({ 9.7+/ 1.2}/{RT}) [molec cm 2 s 1], kcond=2.8×10 2+/-1×exp({+1.5+/ 1.6}/{RT}) [s 1], and an HBr mole fraction smaller than 6.4×10 3:Jev=7.4×1025+/ 1×exp({ 9.1+/ 1.2}/{RT}) [molec cm 2 s 1], kcond=7.1×10 5+ 1×exp({+2.6+/ 1.5}/{RT}) [s 1]}. The small negative activation energy for H2O condensation on ice points to a precursor mechanism. The corresponding enthalpy of sublimation is DHsubl=Eev-Econd=11.9+/ 2.7 kcal mol 1, DHsubl=11.2+/ 2.8 kcal mol 1, and DHsubl=11.7+/ 2.8 kcal mol 1 whose values are identical within experimental uncertainty to the accepted literature value of 12.3 kcal mol 1. Interferometric data at 633 nm and FTIR absorption spectra in transmission support the kinetic results. The data are consistent with a significant lifetime enhancement for HCl- and HBr-contaminated ice particles by a factor of 3–6 and 10–20, respectively, for submonolayer coverages of HX.
Aspectos de la construcción del conocimiento sobre la sociedad
Delval, Juan;
Educar em Revista , 2007, DOI: 10.1590/S0104-40602007000200004
Abstract: the child has to construct models or representations about the reality of the society where he or she lives in order to give a meaning to the surrounding world and, furthermore, taking into consideration that these representations serve as landmarks to his action. most of the mental representations constructed by the child are not simple copies of the adult representations; instead, they are personal constructions and differ qualitatively from those of the older people. the study of the development of knowledge about society in children is attracting the attention of many investigators. there are three main theoretical approaches to this subject: the constructivist position says that the child has to construct their own knowledge counting on their personal intellectual instruments; the traditional study about social representations originated in the french school of sociology, that has been renewed by moscovici; and the historical cultural psychology of vygotskyan approach. the first position emphasizes the activity of the subject, while the others put the emphasis on the environmental influences and so hold a counterpoint to the constructivist position. however, the existence of children beliefs different from those from adults' as well as from the social context, and the universality of some of these beliefs, compel us not to forget the personal work of construction made by the subject.
Freezing of water droplets colliding with kaolinite particles
E. A. Svensson, C. Delval, P. von Hessberg, M. S. Johnson,J. B. C. Pettersson
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2009,
Abstract: Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under relatively dry conditions (when no water vapor was added) freezing was observed to occur below 249 K, while a freezing threshold of 267 K was observed when water vapor was added to the air in the chamber. The effect of relative humidity is attributed to an influence on the contact freezing process for the kaolinite-water droplet system, and it is not related to the lifetime of the droplets in the electrodynamic balance. Freezing probabilities per collision were derived assuming that collisions at the lowest temperature employed had a probability of unity. Mechanisms for contact freezing are briefly discussed.
Freezing of water droplets colliding with kaolinite particles
E. A. Svensson,C. Delval,P. von Hessberg,M. S. Johnson
Atmospheric Chemistry and Physics Discussions , 2009,
Abstract: Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditions freezing was observed to occur below 249 K, while a freezing threshold of 267 K was observed at high relative humidity. The effect of relative humidity is attributed to an influence on the contact freezing process for the kaolinite-water droplet system, and it is not related to the lifetime of the droplets in the electrodynamic balance. Freezing probabilities per collision were derived assuming that collisions at the lowest temperature employed had a probability of unity. The data recorded at high humidity should be most relevant to atmospheric conditions, and the results indicate that parameterizations currently used in modelling studies to describe freezing rates are appropriate for kaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed.
The Pbx Interaction Motif of Hoxa1 Is Essential for Its Oncogenic Activity
Stéphanie Delval, Arnaud Taminiau, Juliette Lamy, Cécile Lallemand, Christine Gilles, Agnès No?l, René Rezsohazy
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0025247
Abstract: Hoxa1 belongs to the Hox family of homeodomain transcription factors involved in patterning embryonic territories and governing organogenetic processes. In addition to its developmental functions, Hoxa1 has been shown to be an oncogene and to be overexpressed in the mammary gland in response to a deregulation of the autocrine growth hormone. It has therefore been suggested that Hoxa1 plays a pivotal role in the process linking autocrine growth hormone misregulation and mammary carcinogenesis. Like most Hox proteins, Hoxa1 can interact with Pbx proteins. This interaction relies on a Hox hexapeptidic sequence centred on conserved Tryptophan and Methionine residues. To address the importance of the Hox-Pbx interaction for the oncogenic activity of Hoxa1, we characterized here the properties of a Hoxa1 variant with substituted residues in the hexapeptide and demonstrate that the Hoxa1 mutant lost its ability to stimulate cell proliferation, anchorage-independent cell growth, and loss of contact inhibition. Therefore, the hexapeptide motif of Hoxa1 is required to confer its oncogenic activity, supporting the view that this activity relies on the ability of Hoxa1 to interact with Pbx.
Endogenous Plasma Peptide Detection and Identification in the Rat by a Combination of Fractionation Methods and Mass Spectrometry
Fabrice Bertile,Flavie Robert,Véronique Delval-Dubois,Sarah Sanglier
Biomarker Insights , 2007,
Abstract: Mass spectrometry-based analyses are essential tools in the field of biomarker research. However, detection and characterization of plasma low abundance and/or low molecular weight peptides is challenged by the presence of highly abundant proteins, salts and lipids. Numerous strategies have already been tested to reduce the complexity of plasma samples. The aim of this study was to enrich the low molecular weight fraction of rat plasma. To this end, we developed and compared simple protocols based on membrane filtration, solid phase extraction, and a combination of both. As assessed by UV absorbance, an albumin depletion 99% was obtained. The multistep fractionation strategy (including reverse phase HPLC) allowed detection, in a reproducible manner (CV [1] 30%–35%), of more than 450 peaks below 3000 Da by MALDI-TOF/MS. A MALDI-TOF/MS-determined LOD as low as 1 fmol/μL was obtained, thus allowing nanoLC-Chip/ MS/MS identification of spiked peptides representing ~10–6% of total proteins, by weight. Signal peptide recovery ranged between 5%–100% according to the spiked peptide considered. Tens of peptide sequence tags from endogenous plasma peptides were also obtained and high confidence identifications of low abundance fibrinopeptide A and B are reported here to show the efficiency of the protocol. It is concluded that the fractionation protocol presented would be of particular interest for future differential (high throughput) analyses of the plasma low molecular weight fraction.
ВПЛИВ Х М ЧНОГО СКЛАДУ НА ТИСК НАСИЧЕНО ПАРИ В МОТОРНИХ Б ОЛОГ ЧНИХ ПАЛИВАХ The influence of chemical composition on the saturated vapor pressure in biological motor fuels Влияние химического состава на давление насыщенного пара в моторных биологических топливах
?.В. Полунк?н,C.О. Зубенко,О.О. Гайдай,А.В. Струнгар
Proceedings of National Aviation University , 2010,
Abstract: Розглянуто вплив випаровуваност альтернативних палив на р шення проблеми холодного пуску двигуна за рахунок використання пропан-бутаново сум ш для п двищення тиску насичено пари. Volatility fuels fraction of the estimated parameters and letkosti. Volatility characterizes the ability to switch fuels in vaporous state. Selecting indicators to assess the volatility depends on the chemical composition of fuel. The main measure letkosti etanolnogo fuel is vapor pressure. The most simple and cost-effective to improve cold start is putting in fuel lehkoletyuchyh components: butane, izopentanu, gas and other petroleum. It was investigated the influence of DEE on alcohol-gasoline blend, the results show that DEE positive impact on increasing vapor pressure to the desired minimum for starting the engine. But because the ether to 19%, then at such high levels can actively formed peroxide compounds, which is undesirable. Very promising is the use of propane-butane gas mixture as lehkoletyuchoyi gaseous component. Butanizovani spirit-petrol mixture can be recommended for use as alternative fuel vehicles after further study of their stability and himmotolohichnyh characteristics. Автомобильные бензины и альтернативные биологические топлива на основе этанола преимущественно предназначены для применения в двигателях внутреннего сгорания. При использовании альтернативного биологического топлива, особенно этанольного, возникает проблема недостаточной испаряемости бензина при низкой температуре, в результате чего в холодное время года двигатель может не запуститься. Пусковые свойства бензина зависят от содержания в них летучих фракций или летучих соединений. Проблему холодного запуска предлагается решать за счет использования пропан-бутановой смеси для повышения давления насыщенного пара. Для перспективного применения газов пропан-бутановой смеси легколетучего газообразного компонента необходимы дальнейшие исследования стабилизации такой композиции.
Strategic trends of development of the Lithuanian aviation in the light of Euro-integration processes Стратегические направления развития авиации литвы в свете евроинтеграции процессов СТРАТЕГ ЧНИЙ НАПРЯМ РОЗВИТКУ АВ АЦ ЛИТВИ У СВ ТЛИ ВРО НТЕГРАЦ ЙНИХ ПРОЦЕС В
Й. Станкунаc
Proceedings of National Aviation University , 2004,
Abstract: The factors having an effect on the system of air transport in the Republic of Lithuania in connection with Lithuania’s membership in the European Union are discussed. The structure of the system of air transport of the country is presented, an analysis of the current situation and a strategic analysis of the development of the system is made, and the measures addressed at the long-range perspective are proposed. Рассмотрены факторы, действующие в системе воздушного транспорта Литовской Республики после вступления в Европейский Союз. Приведена структура системы воздушного транспорта страны и выполнен стратегический анализ развития транспортной системы на долгосрочную перспективу. Розглянуто чинники, що д ють у систем пов тряного транспорту Литовсько Республ ки п сля вступу в вропейський Союз. Подано структуру систем пов тряного транспорту кра ни та виконано стратег чний анал з розвитку транспортно системи на довгострокову перспективу.
LIMIT DISTRIBUTION OF A RANK OF RANDOM SATURATED MATRIX ABOVE A FIELD GF(2) ПРЕДЕЛЬНОЕ РАСПРЕДЕЛЕНИЕ РАНГА СИЛЬНОЗАПОЛНЕННОЙ СЛУЧАЙНОЙ МАТРИЦЫ НАД ПОЛЕМ GF(2) ГРАНИЧНИЙ РОЗПОД Л РАНГУ СИЛЬНОЗАПОВНЕНО ВИПАДКОВО МАТРИЦ В ПОЛ GF(2)
C.В. Поперешняк
Proceedings of National Aviation University , 2012,
Abstract: In this paper a theorem on the asymptotic distribution of rank of random matrices in the field GF (2) of independent random -D lines, the absence in it of unity lines and the assumption that the difference between the number of rows and number of columns of the matrix is a fixed number of random characters, . Получена теорема про асимптотику распределения ранга случайной матрицы над полем GF(2), которая состоит из независимых случайных -мерных строк, при условии отсутствия в ней единичных линий и в предположении, что разница между числом строк и числом столбцов матрицы фиксированное число произвольного знака, . Отримано теорему про асимптотику розпод лу рангу випадково матриц в пол GF(2) з незалежних випадкових -вим рних рядк в за умови в дсутност в н й одиничних л н й та в припущенн , що р зниця м ж числом рядк в та числом стовпц в матриц ф ксоване число дов льного знаку,
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