diana rodriguez - Academia.edu (original) (raw)
Papers by diana rodriguez
FMC - Formación Médica Continuada en Atención Primaria, 2007
M ujer de 65 años de edad, que acude a la consulta por presentar desde hace varios meses lesiones... more M ujer de 65 años de edad, que acude a la consulta por presentar desde hace varios meses lesiones cutáneas faciales asintomáticas, que aparecen en verano y desaparecen o mejoran en los meses de otoño e invierno.
Analysis of variance of saponin content showed significant differences only for water deficit tre... more Analysis of variance of saponin content showed significant differences only for water deficit treatments, stages, and stage × deficit interaction. The saponin content showed highly significant differences (p < 0.01) among the 3 soil water deficit treatments based on analysis of variance. Saponin content for the low soil water deficit plants was 0.456% whereas that for the high water deficit was 0.386%. Highly significant differ- ences (p < 0.01) were also observed among the growing stages. The lowest saponin content (0.309%) was found in the branching stage and the highest (0.608%) in blooming. These results are in agreement with those
Journal of Agronomy and Crop Science, 1994
ABSTRACT The effect of phosphorus nutrition on the development of wheat plants, was studied. Phos... more ABSTRACT The effect of phosphorus nutrition on the development of wheat plants, was studied. Phosphorus deficiency increased the duration of the phyllochron when the concentration in shoots was less than 0.8 %. Phosphorus concentration in shoots appeared to be a good indicator of the effect of plant phosphorus status on wheat development.
La estrategia de diversificación corporativa ha dado lugar a un debate académico y empresarial mu... more La estrategia de diversificación corporativa ha dado lugar a un debate académico y empresarial muy interesante durante las últimas tres décadas. Este trabajo proporciona evidencia adicional del impacto de ésta estrategia sobre el valor de la empresa. Considerando las posibles diferencias en oportunidades de crecimiento entre empresas diversificadas y no diversificadas proponemos un modelo que incorpora un ajuste en la medida de exceso de valor con base en dichas oportunidades. De acuerdo con la tradicional hipótesis de destrucción de valor encontramos un descuento para las empresas del mercado español, sin embargo este descuento desaparece cuando tomamos en consideración las diferencias de oportunidades de crecimiento entre empresas diversificadas y no diversificadas. Consistente con la evidencia empírica obtenida podemos concluir que el impacto de la estrategia de diversificación no es absoluto, más bien es condicional de las opciones de crecimiento que ejercen las empresas.
Brain
In addition to multiple peripheral neuro®bromas, Neuro®bromatosis 1 (NF1) predisposes to CNS tumo... more In addition to multiple peripheral neuro®bromas, Neuro®bromatosis 1 (NF1) predisposes to CNS tumours. Most of them are pilocytic astrocytomas, arise in children and are located in the optic pathways or in the brainstem. The majority are indolent, but factors predictive of poor prognosis have yet to be identi®ed. Furthermore, the incidence and natural history of gliomas of a higher grade, arising in adults or involving other locations are largely unknown in NF1. In order to address these issues, we performed a retrospective study of 104 patients followed in seven French centres between 1982 and 2000. Inclusion criteria were a diagnosis of NF1, according to the National Institutes of Health criteria, and the presence of a CNS tumour, regardless of type, location or age of onset. The series included 88 children (age range 3 months to 17 years) and 16 adults (age range 19±52 years). The median follow-up was 5.6 years. One hundred and twenty-seven CNS tumours were observed in the 104 patients. Eighty-four (66%) were optic pathway tumours (OPT) and 43 (34%) extra-optic pathway tumours (extra-OPT) (brainstem: n = 21; other locations: n = 22). Twentyone patients (20%) had multiple CNS tumours. OPT were symptomatic in 50 patients and extra-OPT in 19. Main clinical ®ndings at presentation included visual loss (n = 29; 58%) and precocious puberty (n = 5; 10%) for OPT, increased intracranial pressure (n = 9; 48%) for extra-OPT. Fourteen out of the 27 symptomatic tumours with histology were pilocytic astrocytomas. The overall survival rate was 90% at 5 years (95% con-®dence interval 82±95%). Extra-optic location, tumour diagnosis in adulthood and symptomatic tumours were independent factors associated with shorter survival time (P < 0.05, Cox model). Radiotherapy for OPT was associated with vascular complications (ischaemic strokes) and growth hormone de®ciency in 32 and 46% of patients, respectively. In conclusion, mortality is high in extra-OPT, particularly in adults, whereas OPT are only exceptionally life-threatening. Radiotherapy of OPT is associated with an important morbidity in NF1.
ATMOSPHERIC CHEMISTRY AND PHYSICS
The uptake of SO 2 onto Saharan mineral dust from the Cape Verde Islands was investigated using a... more The uptake of SO 2 onto Saharan mineral dust from the Cape Verde Islands was investigated using a coated wall flow tube coupled to a mass spectrometer. The rate of loss of SO 2 to the dust coating was measured and uptake coefficients were determined using the measured BET surface area of the sample. The uptake of SO 2 , with an initial concentration between (2-40)×10 10 molecule cm −3 (0.62-12 µTorr), was found to be strongly time dependent over the first few hundred seconds of an experiment, with an initial uptake γ 0,BET of (6.6±0.8)×10 −5 (298 K), declining at longer times. The amount of SO 2 adsorbed on the dust samples was measured over a range of SO 2 concentrations and mineral dust loadings. The uptake of SO 2 was found to be up to 98% irreversible over the timescale of these investigations. Experiments were also performed at 258 K, at a relative humidity of 27% and at 298 K in the presence of ozone. The initial uptake and the amount of SO 2 taken up per unit area of BET dust surface was the same within error, irrespective of the conditions used; however the presence of ozone reduced the amount of SO 2 released back into the gas-phase per unit area once exposure of the surface ended. Multiple uptakes to the same surface revealed a loss of surface reactivity, which did not return if the samples were exposed to gas-phase water, or left under vacuum overnight. A mechanism which accounts for the observed uptake behaviour is proposed and numerically modelled, allowing quantitative estimates of the rate and amount of SO 2 removal in the atmosphere to be estimated. Removal of SO 2 by mineral dust is predicted to be significant at high dust loadings.
Atmospheric Environment
The kinetics of the gas-phase reactions of chlorine atoms with acrylic acid (1) and allyl alcohol... more The kinetics of the gas-phase reactions of chlorine atoms with acrylic acid (1) and allyl alcohol (2) have been investigated at low pressure (0.5-3 Torr) in the temperature range 260-333 K using the mass spectrometric discharge-flow method. The temperature dependence of the reaction rate constants at 1 Torr have been determined under pseudo-first-order conditions in excess of organic compound over Cl atoms, giving: k 1 ¼ ð1:370:9Þ Â 10 À13 expð16007200Þ=T cm 3 molecule À1 s À1 and k 2 ¼ ð1:170:5Þ Â 10 À11 expð4707135Þ=T cm 3 molecule À1 s À1 : At room temperature and 1 Torr; products of abstraction and addition channels have been detected for reactions (1) and (2). By mass spectrometric quantification, the branching ratio for channels giving HCl, was determined as 0:1370:05 for reaction (1) and 0:5770:06 for reaction (2). The results obtained are related to previous studies, and the atmospheric implications are also discussed in relation to the homogeneous sinks of acrylic acid and allyl alcohol. r
Chemical Physics Letters
The kinetics and mechanism of the reaction of chlorine atoms with acrylonitrile (CH 2 CHCN) (1) h... more The kinetics and mechanism of the reaction of chlorine atoms with acrylonitrile (CH 2 CHCN) (1) have been studied by the mass spectrometric discharge-flow method in the temperature range (260-333) K and at a total pressure between 0.5 and 3 Torr. At 1.0 Torr the following Arrhenius expression for the rate constant has been obtained from the kinetics of Cl radical consumption in excess of CH 2 CHCN: k 1 ¼ ð5:2 AE 1:6Þ Â 10 À14 exp½ð1400 AE 100=T Þ cm 3 molecule À1 s À1 . The reaction is found to proceed through an addition mechanism involving a relatively stable adduct. The atmospheric significance of the present results for acrylonitrile is also discussed.
The seed oil of Lesquerella and the closely related genus Physaria (Brassicaceae) is rich in hydr... more The seed oil of Lesquerella and the closely related genus Physaria (Brassicaceae) is rich in hydroxy fatty acids (HFAs). HFAs and their derivatives are used to produce a variety of industrial products including lubricants, nylon-11, plastics, drying agents, protective coatings, surfactants, cosmetics, and pharmaceuticals. Lesquerella fendleri is being developed as a new crop for arid regions of the southwestern United States as an alternative source of HFAs. Between 1995 and 2001, 66 accessions from 28 species of Lesquerella were collected in the United States, 33 accessions from four species were collected in Mexico, and 41 accessions from 15 species of Physaria were collected from the southwestern United States. Mean seed mass ranged from 0.54 to 2.30 mg for Lesquerella compared to 1.70 to 5.80 mg for Physaria. Seed oil content ranged from a high of 32.2% in Lesquerella to a high of 35.4% in Physaria. The fatty acid profile of all species of Physaria and most of the lesquerolic-acid-rich species of Lesquerella contained from 30 to 55% lesquerolic acid, although several species contained Ͼ60%. These collections of wild germplasm provide a diverse gene pool that should enhance our breeding program in developing a domestic source of HFAs.
Journal Français d Ophtalmologie
Environmental Science and Pollution Research, 2015
Ultrafine particles, PM2.5 and PM10 mass concentration, NOx, Ozone, SO2, back-trajectories of air... more Ultrafine particles, PM2.5 and PM10 mass concentration, NOx, Ozone, SO2, back-trajectories of air masses and meteorological parameters were studied in a small city over the period February, 2013 to June, 2014. The profiles of PM2.5 and PM10 particles are provided, showing averaged values of 16.6 and 21.6 μg m(-3), respectively. The average number concentration of particles in the range of diameters 5.6-560 nm was 1.2 × 10(4)#/ cm(3) with contributions of 42, 51 and 7 % from the nucleation, Aitken, and accumulation modes, respectively. The average number concentration of ultrafine particles was 1.1 × 10(4)#/ cm(3). The results obtained are evidence for some differences in the pollution of ambient air by particles in the studied town in comparison to bigger cities. Nucleation events due to emissions from the city were not observed, and traffic emissions amount to a small contribution to PM2.5 and PM10 particles which are mainly due to crustal origin from the arid surroundings and long-range transport from the Sahara Desert.
Atmospheric Environment, 2014
ABSTRACT The atmospheric degradation of two hydrofluoroethers, HFE-7300 [n-C2F5CF(OCH3)CF(CF3)2] ... more ABSTRACT The atmospheric degradation of two hydrofluoroethers, HFE-7300 [n-C2F5CF(OCH3)CF(CF3)2] and HFE-7500 [n-C3F7CF(OC2H5)CF(CF3)2] used in industrial applications has been studied. The kinetics and reaction products were determined at atmospheric pressure as a function of temperature in a reaction chamber using GC/FID and GC/MS techniques for the analysis. The following Arrhenius expressions were obtained (in units of cm3 molecule�1 s�1): kHFE-7300 þ OH ¼ (5.6 ± 2.0) � 10�13 exp(�(1186 ± 111)/T); kHFE-7300 þ Cl ¼ (3.8 ± 1.3) � 10�12 exp(�(968 ± 101)/T); and kHFE-7500 þ OH ¼ (7.6 ± 6.0) � 10�12exp(�(1163 ± 385)/T) (temperature range 271e333 K). The atmospheric lifetimes calculated from kinetic data for HFE-7300 and HFE-7500 were 5.24 and 0.30 years, respectively. In the oxidation of HFE-7300 with OH and Cl radicals, the only detected product was F3CF2CF(OCHO)CF(CF3)2, whereas in the oxidation of HFE-7500 by OH radicals the detected products were: C3F7CF(OC(O)CH3)CF(CF3)2 and C3F7CF(OC(O)H)CF(CF3)2. Infrared spectra of the studied HFEs have also been measured and radiative forcing efficiencies were determined. Combining these results with the kinetic data, we estimated 100- year time horizon global warming potentials of 440 and 12 for HFE-7300 and HFE-7500, respectively
International Journal of Environmental Science and Technology, 2014
ABSTRACT Recently, it has been demonstrated that grass and cut grass are important sources of C6 ... more ABSTRACT Recently, it has been demonstrated that grass and cut grass are important sources of C6 esters’ emissions into the atmosphere. The esters emitted as part of the wound defense mechanisms are responsible for the smell of freshly cut grass and are also highly photochemically reactive. Thus, these grass emissions should be included in models of urban photochemical pollution so that accurate smog predictions can be obtained. In this work, we have carried out a kinetic study of the gas-phase reactions of chlorine atom and hydroxyl radical with cis-3-hexenylformate (HCO2CH2CH2CH=CHC2H5) for the first time. This was performed in a Teflon static reactor at room temperature and atmospheric pressure of nitrogen or air using gas chromatography with flame ionization detection. Kinetic rate coefficients obtained for cis-3-hexenylformate were (in units of cm3 molecule−1 s−1) (2.45 ± 0.30) × 10−10 and (4.61 ± 0.71) × 10−11 for chlorine and hydroxyl radical reactions, respectively. The reaction between the ester and chlorine atoms is very fast, approaching the collision-controlled regime; nevertheless, the rate constant for the reaction with hydroxyl radical is lower. In addition, the rate coefficients for the reactions of cis-3-hexenylformate with different atmospheric reactive species were estimated through a Quantitative Structure–Activity Relationship model in which High Occupied Molecular Orbital energy of the formate is used as a theoretical molecular descriptor. Tropospheric lifetimes, based on the homogeneous sinks of the cis-3-hexenylformate, are estimated from the kinetic data obtained in the present work. The relatively short atmospheric lifetimes of the ester indicate that the compound will be oxidized near its anthropogenic origin source.
Materials Science Forum, 2001
Organic Preparations and Procedures International, 2002
The exudate of Aloe vera L., Liliaceae, is used for numerous medical and cosmetic applications si... more The exudate of Aloe vera L., Liliaceae, is used for numerous medical and cosmetic applications since ancient times . The gel of A. vera possesses various biological and physiological activities: (1) healing ability of skin burns and cutaneous injuries; (2) prophylactic effect against radiation leucopenia; (3) anti-ulcer; (4) inhibitory action against some bacteria and fungi; (5) inflammation-inhibiting effect; (6) inhibition of the prostaglandin synthesis by anthraquinone-type compounds; and inhibition of the AIDS virus by acemannan.
Materials Science Forum, 2003
Archives de Pediatrie, 2002
ABSTRACT Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have ... more ABSTRACT Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have elaborated recommendations for the management of the disease. Bibliography was obtained through a Medline of articles from 1966 to 1999 for the terms neurofibromatosis, NF1, neurofibroma and from textbooks. A consensual document was written taking into account extracted data. An annual careful clinical examination is recommended except in cases with complications. Screening investigations are not recommended due to the rarity of complications, generally symptomatic and easily detected during the clinical follow-up. The only controversial exception might be magnetic resonance imaging for early detection of optic pathway gliomas in young children. A co-ordinated follow-up in specialised multidisciplinary centres, providing patients with a rational management, is recommended.
FMC - Formación Médica Continuada en Atención Primaria, 2007
M ujer de 65 años de edad, que acude a la consulta por presentar desde hace varios meses lesiones... more M ujer de 65 años de edad, que acude a la consulta por presentar desde hace varios meses lesiones cutáneas faciales asintomáticas, que aparecen en verano y desaparecen o mejoran en los meses de otoño e invierno.
Analysis of variance of saponin content showed significant differences only for water deficit tre... more Analysis of variance of saponin content showed significant differences only for water deficit treatments, stages, and stage × deficit interaction. The saponin content showed highly significant differences (p < 0.01) among the 3 soil water deficit treatments based on analysis of variance. Saponin content for the low soil water deficit plants was 0.456% whereas that for the high water deficit was 0.386%. Highly significant differ- ences (p < 0.01) were also observed among the growing stages. The lowest saponin content (0.309%) was found in the branching stage and the highest (0.608%) in blooming. These results are in agreement with those
Journal of Agronomy and Crop Science, 1994
ABSTRACT The effect of phosphorus nutrition on the development of wheat plants, was studied. Phos... more ABSTRACT The effect of phosphorus nutrition on the development of wheat plants, was studied. Phosphorus deficiency increased the duration of the phyllochron when the concentration in shoots was less than 0.8 %. Phosphorus concentration in shoots appeared to be a good indicator of the effect of plant phosphorus status on wheat development.
La estrategia de diversificación corporativa ha dado lugar a un debate académico y empresarial mu... more La estrategia de diversificación corporativa ha dado lugar a un debate académico y empresarial muy interesante durante las últimas tres décadas. Este trabajo proporciona evidencia adicional del impacto de ésta estrategia sobre el valor de la empresa. Considerando las posibles diferencias en oportunidades de crecimiento entre empresas diversificadas y no diversificadas proponemos un modelo que incorpora un ajuste en la medida de exceso de valor con base en dichas oportunidades. De acuerdo con la tradicional hipótesis de destrucción de valor encontramos un descuento para las empresas del mercado español, sin embargo este descuento desaparece cuando tomamos en consideración las diferencias de oportunidades de crecimiento entre empresas diversificadas y no diversificadas. Consistente con la evidencia empírica obtenida podemos concluir que el impacto de la estrategia de diversificación no es absoluto, más bien es condicional de las opciones de crecimiento que ejercen las empresas.
Brain
In addition to multiple peripheral neuro®bromas, Neuro®bromatosis 1 (NF1) predisposes to CNS tumo... more In addition to multiple peripheral neuro®bromas, Neuro®bromatosis 1 (NF1) predisposes to CNS tumours. Most of them are pilocytic astrocytomas, arise in children and are located in the optic pathways or in the brainstem. The majority are indolent, but factors predictive of poor prognosis have yet to be identi®ed. Furthermore, the incidence and natural history of gliomas of a higher grade, arising in adults or involving other locations are largely unknown in NF1. In order to address these issues, we performed a retrospective study of 104 patients followed in seven French centres between 1982 and 2000. Inclusion criteria were a diagnosis of NF1, according to the National Institutes of Health criteria, and the presence of a CNS tumour, regardless of type, location or age of onset. The series included 88 children (age range 3 months to 17 years) and 16 adults (age range 19±52 years). The median follow-up was 5.6 years. One hundred and twenty-seven CNS tumours were observed in the 104 patients. Eighty-four (66%) were optic pathway tumours (OPT) and 43 (34%) extra-optic pathway tumours (extra-OPT) (brainstem: n = 21; other locations: n = 22). Twentyone patients (20%) had multiple CNS tumours. OPT were symptomatic in 50 patients and extra-OPT in 19. Main clinical ®ndings at presentation included visual loss (n = 29; 58%) and precocious puberty (n = 5; 10%) for OPT, increased intracranial pressure (n = 9; 48%) for extra-OPT. Fourteen out of the 27 symptomatic tumours with histology were pilocytic astrocytomas. The overall survival rate was 90% at 5 years (95% con-®dence interval 82±95%). Extra-optic location, tumour diagnosis in adulthood and symptomatic tumours were independent factors associated with shorter survival time (P < 0.05, Cox model). Radiotherapy for OPT was associated with vascular complications (ischaemic strokes) and growth hormone de®ciency in 32 and 46% of patients, respectively. In conclusion, mortality is high in extra-OPT, particularly in adults, whereas OPT are only exceptionally life-threatening. Radiotherapy of OPT is associated with an important morbidity in NF1.
ATMOSPHERIC CHEMISTRY AND PHYSICS
The uptake of SO 2 onto Saharan mineral dust from the Cape Verde Islands was investigated using a... more The uptake of SO 2 onto Saharan mineral dust from the Cape Verde Islands was investigated using a coated wall flow tube coupled to a mass spectrometer. The rate of loss of SO 2 to the dust coating was measured and uptake coefficients were determined using the measured BET surface area of the sample. The uptake of SO 2 , with an initial concentration between (2-40)×10 10 molecule cm −3 (0.62-12 µTorr), was found to be strongly time dependent over the first few hundred seconds of an experiment, with an initial uptake γ 0,BET of (6.6±0.8)×10 −5 (298 K), declining at longer times. The amount of SO 2 adsorbed on the dust samples was measured over a range of SO 2 concentrations and mineral dust loadings. The uptake of SO 2 was found to be up to 98% irreversible over the timescale of these investigations. Experiments were also performed at 258 K, at a relative humidity of 27% and at 298 K in the presence of ozone. The initial uptake and the amount of SO 2 taken up per unit area of BET dust surface was the same within error, irrespective of the conditions used; however the presence of ozone reduced the amount of SO 2 released back into the gas-phase per unit area once exposure of the surface ended. Multiple uptakes to the same surface revealed a loss of surface reactivity, which did not return if the samples were exposed to gas-phase water, or left under vacuum overnight. A mechanism which accounts for the observed uptake behaviour is proposed and numerically modelled, allowing quantitative estimates of the rate and amount of SO 2 removal in the atmosphere to be estimated. Removal of SO 2 by mineral dust is predicted to be significant at high dust loadings.
Atmospheric Environment
The kinetics of the gas-phase reactions of chlorine atoms with acrylic acid (1) and allyl alcohol... more The kinetics of the gas-phase reactions of chlorine atoms with acrylic acid (1) and allyl alcohol (2) have been investigated at low pressure (0.5-3 Torr) in the temperature range 260-333 K using the mass spectrometric discharge-flow method. The temperature dependence of the reaction rate constants at 1 Torr have been determined under pseudo-first-order conditions in excess of organic compound over Cl atoms, giving: k 1 ¼ ð1:370:9Þ Â 10 À13 expð16007200Þ=T cm 3 molecule À1 s À1 and k 2 ¼ ð1:170:5Þ Â 10 À11 expð4707135Þ=T cm 3 molecule À1 s À1 : At room temperature and 1 Torr; products of abstraction and addition channels have been detected for reactions (1) and (2). By mass spectrometric quantification, the branching ratio for channels giving HCl, was determined as 0:1370:05 for reaction (1) and 0:5770:06 for reaction (2). The results obtained are related to previous studies, and the atmospheric implications are also discussed in relation to the homogeneous sinks of acrylic acid and allyl alcohol. r
Chemical Physics Letters
The kinetics and mechanism of the reaction of chlorine atoms with acrylonitrile (CH 2 CHCN) (1) h... more The kinetics and mechanism of the reaction of chlorine atoms with acrylonitrile (CH 2 CHCN) (1) have been studied by the mass spectrometric discharge-flow method in the temperature range (260-333) K and at a total pressure between 0.5 and 3 Torr. At 1.0 Torr the following Arrhenius expression for the rate constant has been obtained from the kinetics of Cl radical consumption in excess of CH 2 CHCN: k 1 ¼ ð5:2 AE 1:6Þ Â 10 À14 exp½ð1400 AE 100=T Þ cm 3 molecule À1 s À1 . The reaction is found to proceed through an addition mechanism involving a relatively stable adduct. The atmospheric significance of the present results for acrylonitrile is also discussed.
The seed oil of Lesquerella and the closely related genus Physaria (Brassicaceae) is rich in hydr... more The seed oil of Lesquerella and the closely related genus Physaria (Brassicaceae) is rich in hydroxy fatty acids (HFAs). HFAs and their derivatives are used to produce a variety of industrial products including lubricants, nylon-11, plastics, drying agents, protective coatings, surfactants, cosmetics, and pharmaceuticals. Lesquerella fendleri is being developed as a new crop for arid regions of the southwestern United States as an alternative source of HFAs. Between 1995 and 2001, 66 accessions from 28 species of Lesquerella were collected in the United States, 33 accessions from four species were collected in Mexico, and 41 accessions from 15 species of Physaria were collected from the southwestern United States. Mean seed mass ranged from 0.54 to 2.30 mg for Lesquerella compared to 1.70 to 5.80 mg for Physaria. Seed oil content ranged from a high of 32.2% in Lesquerella to a high of 35.4% in Physaria. The fatty acid profile of all species of Physaria and most of the lesquerolic-acid-rich species of Lesquerella contained from 30 to 55% lesquerolic acid, although several species contained Ͼ60%. These collections of wild germplasm provide a diverse gene pool that should enhance our breeding program in developing a domestic source of HFAs.
Journal Français d Ophtalmologie
Environmental Science and Pollution Research, 2015
Ultrafine particles, PM2.5 and PM10 mass concentration, NOx, Ozone, SO2, back-trajectories of air... more Ultrafine particles, PM2.5 and PM10 mass concentration, NOx, Ozone, SO2, back-trajectories of air masses and meteorological parameters were studied in a small city over the period February, 2013 to June, 2014. The profiles of PM2.5 and PM10 particles are provided, showing averaged values of 16.6 and 21.6 μg m(-3), respectively. The average number concentration of particles in the range of diameters 5.6-560 nm was 1.2 × 10(4)#/ cm(3) with contributions of 42, 51 and 7 % from the nucleation, Aitken, and accumulation modes, respectively. The average number concentration of ultrafine particles was 1.1 × 10(4)#/ cm(3). The results obtained are evidence for some differences in the pollution of ambient air by particles in the studied town in comparison to bigger cities. Nucleation events due to emissions from the city were not observed, and traffic emissions amount to a small contribution to PM2.5 and PM10 particles which are mainly due to crustal origin from the arid surroundings and long-range transport from the Sahara Desert.
Atmospheric Environment, 2014
ABSTRACT The atmospheric degradation of two hydrofluoroethers, HFE-7300 [n-C2F5CF(OCH3)CF(CF3)2] ... more ABSTRACT The atmospheric degradation of two hydrofluoroethers, HFE-7300 [n-C2F5CF(OCH3)CF(CF3)2] and HFE-7500 [n-C3F7CF(OC2H5)CF(CF3)2] used in industrial applications has been studied. The kinetics and reaction products were determined at atmospheric pressure as a function of temperature in a reaction chamber using GC/FID and GC/MS techniques for the analysis. The following Arrhenius expressions were obtained (in units of cm3 molecule�1 s�1): kHFE-7300 þ OH ¼ (5.6 ± 2.0) � 10�13 exp(�(1186 ± 111)/T); kHFE-7300 þ Cl ¼ (3.8 ± 1.3) � 10�12 exp(�(968 ± 101)/T); and kHFE-7500 þ OH ¼ (7.6 ± 6.0) � 10�12exp(�(1163 ± 385)/T) (temperature range 271e333 K). The atmospheric lifetimes calculated from kinetic data for HFE-7300 and HFE-7500 were 5.24 and 0.30 years, respectively. In the oxidation of HFE-7300 with OH and Cl radicals, the only detected product was F3CF2CF(OCHO)CF(CF3)2, whereas in the oxidation of HFE-7500 by OH radicals the detected products were: C3F7CF(OC(O)CH3)CF(CF3)2 and C3F7CF(OC(O)H)CF(CF3)2. Infrared spectra of the studied HFEs have also been measured and radiative forcing efficiencies were determined. Combining these results with the kinetic data, we estimated 100- year time horizon global warming potentials of 440 and 12 for HFE-7300 and HFE-7500, respectively
International Journal of Environmental Science and Technology, 2014
ABSTRACT Recently, it has been demonstrated that grass and cut grass are important sources of C6 ... more ABSTRACT Recently, it has been demonstrated that grass and cut grass are important sources of C6 esters’ emissions into the atmosphere. The esters emitted as part of the wound defense mechanisms are responsible for the smell of freshly cut grass and are also highly photochemically reactive. Thus, these grass emissions should be included in models of urban photochemical pollution so that accurate smog predictions can be obtained. In this work, we have carried out a kinetic study of the gas-phase reactions of chlorine atom and hydroxyl radical with cis-3-hexenylformate (HCO2CH2CH2CH=CHC2H5) for the first time. This was performed in a Teflon static reactor at room temperature and atmospheric pressure of nitrogen or air using gas chromatography with flame ionization detection. Kinetic rate coefficients obtained for cis-3-hexenylformate were (in units of cm3 molecule−1 s−1) (2.45 ± 0.30) × 10−10 and (4.61 ± 0.71) × 10−11 for chlorine and hydroxyl radical reactions, respectively. The reaction between the ester and chlorine atoms is very fast, approaching the collision-controlled regime; nevertheless, the rate constant for the reaction with hydroxyl radical is lower. In addition, the rate coefficients for the reactions of cis-3-hexenylformate with different atmospheric reactive species were estimated through a Quantitative Structure–Activity Relationship model in which High Occupied Molecular Orbital energy of the formate is used as a theoretical molecular descriptor. Tropospheric lifetimes, based on the homogeneous sinks of the cis-3-hexenylformate, are estimated from the kinetic data obtained in the present work. The relatively short atmospheric lifetimes of the ester indicate that the compound will be oxidized near its anthropogenic origin source.
Materials Science Forum, 2001
Organic Preparations and Procedures International, 2002
The exudate of Aloe vera L., Liliaceae, is used for numerous medical and cosmetic applications si... more The exudate of Aloe vera L., Liliaceae, is used for numerous medical and cosmetic applications since ancient times . The gel of A. vera possesses various biological and physiological activities: (1) healing ability of skin burns and cutaneous injuries; (2) prophylactic effect against radiation leucopenia; (3) anti-ulcer; (4) inhibitory action against some bacteria and fungi; (5) inflammation-inhibiting effect; (6) inhibition of the prostaglandin synthesis by anthraquinone-type compounds; and inhibition of the AIDS virus by acemannan.
Materials Science Forum, 2003
Archives de Pediatrie, 2002
ABSTRACT Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have ... more ABSTRACT Twenty experts, members of a French medical network devoted to neurofibromatosis 1 have elaborated recommendations for the management of the disease. Bibliography was obtained through a Medline of articles from 1966 to 1999 for the terms neurofibromatosis, NF1, neurofibroma and from textbooks. A consensual document was written taking into account extracted data. An annual careful clinical examination is recommended except in cases with complications. Screening investigations are not recommended due to the rarity of complications, generally symptomatic and easily detected during the clinical follow-up. The only controversial exception might be magnetic resonance imaging for early detection of optic pathway gliomas in young children. A co-ordinated follow-up in specialised multidisciplinary centres, providing patients with a rational management, is recommended.