Pour voir les autres types de publications sur ce sujet consultez le lien suivant : VOC (Volatile organic compounds).
Articles de revues sur le sujet « VOC (Volatile organic compounds) »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « VOC (Volatile organic compounds) ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Fons, Françoise, Didier Froissard, Jean-Marie Bessière, Bruno Buatois et Sylvie Rapior. « Biodiversity of Volatile Organic Compounds from Five French Ferns ». Natural Product Communications 5, no 10 (octobre 2010) : 1934578X1000501. http://dx.doi.org/10.1177/1934578x1000501028.
Texte intégralRésumé :
Five French ferns belonging to different families were investigated for volatile organic compounds (VOC) by GC-MS using organic solvent extraction. Fifty-five VOC biosynthesized from the shikimic, lipidic and terpenic pathways including monoterpenes, sesquiterpenes and carotenoid-type compounds were identified. The main volatile compound of Adiantum Capillus-Veneris L. (Pteridaceae) was ( E)-2-decenal with a plastic or “stink bug” odor. The volatile profiles of Athyrium filix-femina (L.) Roth (Woodsiaceae) and Blechnum spicant (L.) Roth (Blechnaceae) showed similarities, with small amounts of isoprenoids and the same main volatile compounds, i.e., 2-phenylethanal (odor of lilac and hyacinth) and 1-octen-3-ol (mushroom-like odor). The main volatile compound of Dryopteris filix-mas (L.) Schott (Dryopteridaceae) was ( E)-nerolidol with a woody or fresh bark note. Polyketides, as acylfilicinic acids, were mainly identified in this fern. Oreopteris limbosperma (Bellardi ex. All.) J. Holub (Thelypteridaceae), well-known for its lemon smell, contained the highest biodiversity of VOC. Eighty percent of the volatiles was issued from the terpenic pathway. The main volatiles were ( E)-nerolidol, α-terpineol, β-caryophyllene and other minor monoterpenes (for example, linalool, pinenes, limonene, and γ-terpinen-7-al). It was also the fern with the highest number of carotenoid-type derivatives, which were identified in large amounts. Our results were of great interest underlying new industrial valorisation for ferns based on their broad spectrum of volatiles.
2
Jergl, Zdeněk. « Long-term VOC emissions emitted by furniture parts ». Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 55, no 1 (2007) : 65–70. http://dx.doi.org/10.11118/actaun200755010065.
Texte intégralRésumé :
The contribution refers to the problems of long-lasting emissions of VOC (volatile organic compounds) emitted from surface finishing furniture components. Furniture is one of the sources of VOC (volatile organic compounds) in living and working environment. By long-lasting affecting on a human body, higher emission concentrations of VOC in interior can cause health problems.Time is a significant factor influencing the number of VOC (volatile organic compounds) emitted from surface finishing furniture components. The number of long-term emissions was examined in particular phases of production of furniture components.The comparison was focused on a difference in surface finishing of furniture components with water-diluted materials and solvent lacquer materials.The compound of water-diluted materials and solvent lacquer materials has an effect of a quantity of emitted VOC.The quantitative and qualitative determination of VOC emissions from lacquer materials is the result of the carried out analyses.
3
Apriyanto, Donni Kis, et Mitrayana Mitrayana. « SERAPAN SENYAWA ORGANIK VOLATIL SEBAGAI BIOMARKER PENYAKIT KANKER PARU : SUATU MINI REVIEW ». Biomedika 12, no 2 (30 août 2020) : 58–64. http://dx.doi.org/10.23917/biomedika.v12i2.10114.
Texte intégralRésumé :
ABSTRAKUlasan ini merupakan hasil studi literatur yang memberikan tinjauan umum serapan senyawa-senyawa organik volatil yang dianggap sebagai biomarker kanker paru. Senyawa-senyawa ini dapat menyerap pada panjang gelombang tertentu. Senyawa-senyawa organik volatil yang teridentifikasi didaftar dan dijabarkan panjang gelombang yang dapat mereka serap. Studi literatur ini menyajikan kelompok senyawa-senyawa organik volatil dapat menyerap pada rentang panjang gelombang inframerah. Hasil ulasan ini mungkin dapat bermanfaat untuk pengembangan skrinning kanker paru dengan menggunakan alat spektroskopi fotoakustik yang menggunakan sumber laser pada rentang panjang gelombang inframerah atau ultraviolet dengan memanfaatkan serapan panjang gelombang oleh senyawa-senyawa tertentu.Keyword: Biomarker Kanker Paru,Senyawa Organik Volatil, Spektroskopi ABSTRACTThis review is the result of a literature study that provides a general collection of volatile organic compounds (VOC) which are considered as markers for lung cancer. These compounds can absorb certain long waves. The volatile organic compounds identified are listed and described in wavelengths that they can absorb. Literature studies that produce volatile organic compounds in the analysis wavelength range. The results of this review may be useful for the development of lung cancer screening by photoacoustic spectroscopic devices that use laser sources in the range of infrared or ultraviolet wavelengths by utilizing wavelength absorb by certain compounds.Keyword: Lung Cancer Biomarker, Volatile Organic Compounds, Spectroscopy
4
Kornilova, Anna, Lin Huang, Marina Saccon et Jochen Rudolph. « Stable carbon isotope ratios of ambient aromatic volatile organic compounds ». Atmospheric Chemistry and Physics 16, no 18 (21 septembre 2016) : 11755–72. http://dx.doi.org/10.5194/acp-16-11755-2016.
Texte intégralRésumé :
Abstract. Measurements of mixing ratios and stable carbon isotope ratios of aromatic volatile organic compounds (VOC) in the atmosphere were made in Toronto (Canada) in 2009 and 2010. Consistent with the kinetic isotope effect for reactions of aromatic VOC with the OH radical the observed stable carbon isotope ratios are on average significantly heavier than the isotope ratios of their emissions. The change of carbon isotope ratio between emission and observation is used to determine the extent of photochemical processing (photochemical age, ∫ [OH]dt) of the different VOC. It is found that ∫ [OH]dt of different VOC depends strongly on the VOC reactivity. This demonstrates that for this set of observations the assumption of a uniform ∫ [OH]dt for VOC with different reactivity is not justified and that the observed values for ∫ [OH]dt are the result of mixing of VOC from air masses with different values for ∫ [OH]dt. Based on comparison between carbon isotope ratios and VOC concentration ratios it is also found that the varying influence of sources with different VOC emission ratios has a larger impact on VOC concentration ratios than photochemical processing. It is concluded that for this data set the use of VOC concentration ratios to determine ∫ [OH]dt would result in values for ∫ [OH]dt inconsistent with carbon isotope ratios and that the concept of a uniform ∫ [OH]dt for an air mass has to be replaced by the concept of individual values of an average ∫ [OH]dt for VOC with different reactivity.
5
Suschka, Jan, Bozena Mrowiec et Grazyna Kuszmider. « Volatile organic compounds (VOC) at some sewage treatment plants in Poland ». Water Science and Technology 33, no 12 (1 juin 1996) : 273–76. http://dx.doi.org/10.2166/wst.1996.0348.
Texte intégralRésumé :
Volatile organic compounds have been measured at two relatively large sewage treatment plants. Quantitative estimation of benzene, toluene, m.p-xylene, o-xylene and isopropylbenzene have been made for raw sewage, sewage after primary treatment and after biological treatment. Also measurements of 14 different volatile organic compounds in the ambient air, close to screens, and the air above (0.5 m above) aeration tanks have been done. Tests on air stripping of added volatile organic compounds to clean water have been performed in parallel in the laboratory. The removal of examined VOCs in full scale treatment plants was very much below the expected level. In the low loaded activated sludge process the removal was between 2 and 56%, depending on the compound considered. The behavior of volatile organic compounds in laboratory tests was very much different. The concentration of VOCs in the air of rooms where bar racks have been installed was found to be very high. The concentration of toluene in the ambient air could be as high as 460 μg/m3.
6
Yu, Man, Shao Peng Wu, Mei Zhu Chen et Hong Hua Zhang. « Evaluation of Volatile Organic Compounds from Asphalt Using UV-Visible Spectrometer ». Advanced Materials Research 472-475 (février 2012) : 432–36. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.432.
Texte intégralRésumé :
In order to evaluate volatile organic compounds (VOC) from asphalt, this paper explored to use ultraviolet and visible spectroscopy (UV-VIS) as the detection method of VOC. 288nm wavelength was selected as the characteristic absorption wavelength of VOC, finding that VOC quality and its absorbance value showed a good linear relationship which could be the basis for evaluation in this research. Experiments were carried out under different conditions, results of which showed that VOC emission was related to temperatures and asphalt specimens. Moreover, VOC emission increased with increasing temperatures. Results under non-high temperatures conditions showed that VOC emission during its service process should not be ignored.
7
Álvarez-García, Samuel, Sara Mayo-Prieto, Guzmán Carro-Huerga, Álvaro Rodríguez-González, Óscar González-López, Santiago Gutiérrez et Pedro A. Casquero. « Volatile Organic Compound Chamber : A Novel Technology for Microbiological Volatile Interaction Assays ». Journal of Fungi 7, no 4 (25 mars 2021) : 248. http://dx.doi.org/10.3390/jof7040248.
Texte intégralRésumé :
The interest in the study of microbiological interactions mediated by volatile organic compounds (VOCs) has steadily increased in the last few years. Nevertheless, most assays still rely on the use of non-specific materials. We present a new tool, the volatile organic compound chamber (VOC chamber), specifically designed to perform these experiments. The novel devices were tested using four Trichoderma strains against Fusarium oxysporum and Rhizoctonia solani. We demonstrate that VOC chambers provide higher sensitivity and selectivity between treatments and higher homogeneity of results than the traditional method. VOC chambers are also able to test both vented and non-vented conditions. We prove that ventilation plays a very important role regarding volatile interactions, up to the point that some growth-inhibitory effects observed in closed environments switch to promoting ones when tested in vented conditions. This promoting activity seems to be related to the accumulation of squalene by T. harzianum. The VOC chambers proved to be an easy, homogeneous, flexible, and repeatable method, able to better select microorganisms with high biocontrol activity and to guide the future identification of new bioactive VOCs and their role in microbial interactions.
8
Kratt, Lothar, et Johannes Münz. « UV-Licht gegen VOC ». UmweltMagazin 51, no 05-06 (2021) : 12–14. http://dx.doi.org/10.37544/0173-363x-2021-05-06-12.
Texte intégral
9
Liu, Yu, Jun Shen et Xiao Dong Zhu. « Volatile Organic Compounds Emissions of Particleboards in Response to Processing Parameters ». Advanced Materials Research 250-253 (mai 2011) : 943–46. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.943.
Texte intégralRésumé :
The purpose of this study is to reveal the concentration variations of VOC concentrations of larch particleboards with different processing parameters. The mat moisture content (MC), panel type and density were chosen as the influencing factors to investigate the VOC emissions after processing, and consequently provide basic guideline for the selection of processing parameters of particleboards to control the pollutants. 1m3 environmental chamber and portable VOC monitor were used for VOC sampling and analysis. The results showed that these factors had significant impact on VOC concentrations. The increase of MC, board panel and density had a positive effect on VOC emissions. With the MC and board density various in the ranges from 6%-14% and 0.60-0.80 g·cm-3, the TVOC concentrations increased 42.6% and 74.7% separately. The three layers particleboard had the higher concentration than the single layer particleboard.
10
Sun, Shi Jing, et Jun Shen. « Study on Reducing the Volatile Organic Compounds Emissions from Different Processing Particleboards ». Advanced Materials Research 113-116 (juin 2010) : 1101–5. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.1101.
Texte intégralRésumé :
The aim of this paper is to study on how to control VOC emissions from wood-based panel manufacturing. Total volatile organic compounds (TVOC) emissions from larch particleboard under different processing conditions were collected by an environmental chamber. VOC samples were prepared by desiccator, adsorbed by activated carbon, desorpted with Methylene dichloride and measured by GC/MS. The result showed that the optimal process parameters were single-layer structure, moisture content of 6%, density of 0.60 g•cm-3, thickness of 8mm, resin content of 7%, hot-pressing time of 4min.TVOC increased with board density going up，hot-pressing time increasing, moisture content and resin content rising. The predominant compounds emissions from the particleboards are aromatic compound and hydrocarbon. 24 kinds of compounds were identified from the standard board. With hydrocarbon decreasing, aromatic VOC type increased.
11
Malone, Shealyn C., David K. Weaver, Tim F. Seipel, Fabian D. Menalled, Megan L. Hofland, Justin B. Runyon et Amy M. Trowbridge. « Herbivore-induced volatile emissions are altered by soil legacy effects in cereal cropping systems ». Plant and Soil 455, no 1-2 (21 août 2020) : 171–86. http://dx.doi.org/10.1007/s11104-020-04674-2.
Texte intégralRésumé :
Abstract Aims (main purpose and research question) Soil properties, including microbial composition and nutrient availability, can influence the emissions of plant volatile organic compounds (VOCs) that serve as host-location cues for insect pests and their natural enemies. Agricultural practices have profound effects on soil properties, but how these influence crop VOCs remains largely unknown. The aim of this study was to investigate the effect of agricultural practices on constitutive and herbivore-induced VOC emissions by a major staple crop through soil legacy effects. Methods In a full factorial experiment, we measured VOC emissions by wheat (Triticum aestivum) grown in soil inoculum from wheat-fallow or wheat-cover crop rotations that was subjected to feeding by larval Cephus cinctus. Results (main findings) Under herbivory, plants grown in cover crop inoculum emitted greater total VOCs, including higher concentrations of 2-pentadecanone, an insect repellent, and nonanal, a compound important in the recruitment of natural enemies. Plants grown in fallow inoculum showed no differences in emissions whether under herbivory or not. Soil inoculum did not influence VOC emissions of plants in the absence of larval feeding. Conclusions These results suggest that agricultural practices influence crop VOC emissions through soil legacy effects. Additionally, crops grown in wheat-fallow rotations may be less successful recruiting natural enemies of pests through herbivore-induced VOC signaling. Abbreviations Volatile organic compounds (VOCs); herbivore-induced plant volatiles (HIPV); green leaf volatiles (GLVs); northern Great Plains (NGP); wheat stem sawfly (WSS); gas chromatography-mass spectrometry (GC-MS); non-metric multidimensional scaling (NMDS); generalized linear mixed-effects model (GLMM).
12
Acton, W. Joe F., Zhonghui Huang, Brian Davison, Will S. Drysdale, Pingqing Fu, Michael Hollaway, Ben Langford et al. « Surface–atmosphere fluxes of volatile organic compounds in Beijing ». Atmospheric Chemistry and Physics 20, no 23 (7 décembre 2020) : 15101–25. http://dx.doi.org/10.5194/acp-20-15101-2020.
Texte intégralRésumé :
Abstract. Mixing ratios of volatile organic compounds (VOCs) were recorded in two field campaigns in central Beijing as part of the Air Pollution and Human Health in a Chinese Megacity (APHH) project. These data were used to calculate, for the first time in Beijing, the surface–atmosphere fluxes of VOCs using eddy covariance, giving a top-down estimation of VOC emissions from a central area of the city. The results were then used to evaluate the accuracy of the Multi-resolution Emission Inventory for China (MEIC). The APHH winter and summer campaigns took place in November and December 2016 and May and June 2017, respectively. The largest VOC fluxes observed were of small oxygenated compounds such as methanol, ethanol + formic acid and acetaldehyde, with average emission rates of 8.31 ± 8.5, 3.97 ± 3.9 and 1.83 ± 2.0 nmol m−2 s−1, respectively, in the summer. A large flux of isoprene was observed in the summer, with an average emission rate of 5.31 ± 7.7 nmol m−2 s−1. While oxygenated VOCs made up 60 % of the molar VOC flux measured, when fluxes were scaled by ozone formation potential and peroxyacyl nitrate (PAN) formation potential the high reactivity of isoprene and monoterpenes meant that these species represented 30 % and 28 % of the flux contribution to ozone and PAN formation potential, respectively. Comparison of measured fluxes with the emission inventory showed that the inventory failed to capture the magnitude of VOC emissions at the local scale.
13
Shammay, A., I. Evanson et R. M. Stuetz. « A comparison of removal performance of volatile organic and sulfurous compounds between odour abatement systems ». Water Science and Technology 77, no 11 (17 mai 2018) : 2657–67. http://dx.doi.org/10.2166/wst.2018.223.
Texte intégralRésumé :
Abstract Three types of odour abatement systems in sewer networks in Australia were studied for 18 months to determine the removals of different compounds. Six volatile sulfurous compounds and seven volatile organic compounds (VOCs) were further investigated. All types of odour abatement systems exhibited good removal of hydrogen sulfide with the biotrickling filters (BTFs) showing the highest consistent removal. Biofilters outperformed BTFs and activated carbon (AC) filters in the removal of dimethyl mono-, di- and tri-sulfide species at the low inlet concentrations typically found. AC filters exhibited little VOC removal with no compound consistently identified as having a removal greater than 0%. Biofilters outperformed BTFs in VOC removal, yet both had high removal variability.
14
Langford, B., E. Nemitz, E. House, G. J. Phillips, D. Famulari, B. Davison, J. R. Hopkins, A. C. Lewis et C. N. Hewitt. « Fluxes and concentrations of volatile organic compounds above central London, UK ». Atmospheric Chemistry and Physics Discussions 9, no 4 (14 août 2009) : 17297–333. http://dx.doi.org/10.5194/acpd-9-17297-2009.
Texte intégralRésumé :
Abstract. Concentrations and fluxes of eight volatile organic compounds (VOCs) were measured during October 2006 from a high telecom tower above central London, as part of the CityFlux contribution to the REPARTEE I campaign. A continuous flow disjunct eddy covariance technique with analysis by proton transfer reaction mass spectrometry was used. Daily averaged VOC mixing ratios were within the range 1–19 ppb for the oxygenated compounds (methanol, acetaldehyde and acetone) and 0.2–1.3 ppb for the aromatics (benzene, toluene and ethylbenzene). Typical VOC fluxes were in the range 0.1–1.0 mg m−2 h−1. There was a non-linear relationship between VOC fluxes and traffic density for most of the measured compounds. Traffic activity was estimated to account for approximately 70% of the aromatic compound fluxes, whereas non-traffic related sources were found to be more important for methanol and isoprene fluxes. The measured fluxes were comparable to the estimates of the UK national atmospheric emission inventory for the aromatic VOCs and CO. In contrast, fluxes of the oxygenated compounds were about three times larger than inventory estimates. For isoprene and acetonitrile this difference was many times larger. At temperatures over 25°C it is estimated that more than half the isoprene observed in central London is of biogenic origin.
15
Langford, B., E. Nemitz, E. House, G. J. Phillips, D. Famulari, B. Davison, J. R. Hopkins, A. C. Lewis et C. N. Hewitt. « Fluxes and concentrations of volatile organic compounds above central London, UK ». Atmospheric Chemistry and Physics 10, no 2 (22 janvier 2010) : 627–45. http://dx.doi.org/10.5194/acp-10-627-2010.
Texte intégralRésumé :
Abstract. Concentrations and fluxes of eight volatile organic compounds (VOCs) were measured during October 2006 from a high telecom tower above central London, as part of the CityFlux contribution to the REPARTEE I campaign. A continuous flow disjunct eddy covariance technique with analysis by proton transfer reaction mass spectrometry was used. Daily averaged VOC mixing ratios were within the range 1–19 ppb for the oxygenated compounds (methanol, acetaldehyde and acetone) and 0.2–1.3 ppb for the aromatics (benzene, toluene and C2-benzenes). Typical VOC fluxes were in the range 0.1–1.0 mg m−2 h−1. There was a non-linear relationship between VOC fluxes and traffic density for most of the measured compounds. Traffic activity was estimated to account for approximately 70% of the aromatic compound fluxes, whereas non-traffic related sources were found to be more important for methanol and isoprene fluxes. The measured fluxes were comparable to the estimates of the UK national atmospheric emission inventory for the aromatic VOCs and CO. In contrast, fluxes of the oxygenated compounds were about three times larger than inventory estimates. For isoprene and acetonitrile this difference was many times larger. At temperatures over 25° C it is estimated that more than half the isoprene observed in central London is of biogenic origin.
16
Čech, Petr. « Influence of adhesive bonding on quantity of emissions VOCs ». Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 56, no 4 (2008) : 29–36. http://dx.doi.org/10.11118/actaun200856040029.
Texte intégralRésumé :
The study deals with the influence of urea-formaldehyde glue and veneered bolstering on technological operation veneering on quantity of emission VOCs (volatile organic compounds).The so-called Volatile Organic Compounds (VOC) are among the largest pollution sources of both the internal and external environments.VOC is defined as emission of any organic compound or a mixture thereof, with the exception of methane, whereby the compound exerts the pressure of 0.01 kPa or more at the temperature of 20 °C (293.15 K) and reaches the corresponding volatility under the specific conditions of its use and can undergo photochemical reactions with nitrogen oxides when exposed to solar radiation.The effects of VOC upon environment can be described by equation:VOC + NOx + UV radiation + heat = tropospheric ozone (O3).In this work there were tested background working environment in various parts of multi-storeyed press, next was judged emissive charge of veneered device and used glue. We used surface material such as chipboard. We used urea-formaldehyde glue KRONOCOL U300 on technological operation veneering.The VOC emissions from the wooden surfaces with or without finishing were tested in the Equipment for VOC Measuring with a small-space chamber. This equipment was installed in and made available by the Institute of Furniture, Design and Habitation. The small-space chamber is suitable for testing small parts of wood products. The device equipped with small-chamber satisfies all conditions mandated in the standard ENV 13 419 DIN -V-ENV 13 419 ”Determination of the emissions of Volatile organic compounds”.The VOC emissions were collected in columns with sorbent Tenax TA. We analyzed the columns with the VOC emissions by: the gas chromatography in conjunction with mass spectrometer and Direct Thermal Desorption.
17
Robin, Yannick, Johannes Amann, Tobias Baur, Payman Goodarzi, Caroline Schultealbert, Tizian Schneider et Andreas Schütze. « High-Performance VOC Quantification for IAQ Monitoring Using Advanced Sensor Systems and Deep Learning ». Atmosphere 12, no 11 (10 novembre 2021) : 1487. http://dx.doi.org/10.3390/atmos12111487.
Texte intégralRésumé :
With air quality being one target in the sustainable development goals set by the United Nations, accurate monitoring also of indoor air quality is more important than ever. Chemiresistive gas sensors are an inexpensive and promising solution for the monitoring of volatile organic compounds, which are of high concern indoors. To fully exploit the potential of these sensors, advanced operating modes, calibration, and data evaluation methods are required. This contribution outlines a systematic approach based on dynamic operation (temperature-cycled operation), randomized calibration (Latin hypercube sampling), and the use of advances in deep neural networks originally developed for natural language processing and computer vision, applying this approach to volatile organic compound measurements for indoor air quality monitoring. This paper discusses the pros and cons of deep neural networks for volatile organic compound monitoring in a laboratory environment by comparing the quantification accuracy of state-of-the-art data evaluation methods with a 10-layer deep convolutional neural network (TCOCNN). The overall performance of both methods was compared for complex gas mixtures with several volatile organic compounds, as well as interfering gases and changing ambient humidity in a comprehensive lab evaluation. Furthermore, both were tested under realistic conditions in the field with additional release tests of volatile organic compounds. The results obtained during field testing were compared with analytical measurements, namely the gold standard gas chromatography mass spectrometry analysis based on Tenax sampling, as well as two mobile systems, a gas chromatograph with photo-ionization detection for volatile organic compound monitoring and a gas chromatograph with a reducing compound photometer for the monitoring of hydrogen. The results showed that the TCOCNN outperforms state-of-the-art data evaluation methods, for example for critical pollutants such as formaldehyde, achieving an uncertainty of around 11 ppb even in complex mixtures, and offers a more robust volatile organic compound quantification in a laboratory environment, as well as in real ambient air for most targets.
18
Benard, S., M. Ousmane, L. Retailleau, A. Boreave, P. Vernoux et A. Giroir-Fendler. « Catalytic removal of propene and toluene in air over noble metal catalystThis article is one of a selection of papers published in this Special Issue on Biological Air Treatment. » Canadian Journal of Civil Engineering 36, no 12 (décembre 2009) : 1935–45. http://dx.doi.org/10.1139/l09-135.
Texte intégralRésumé :
In this paper we present the study of catalytic oxidation of volatile organic compound (VOC) traces in air over Pt/γ-Al2O3 catalysts. The study was carried out using a laboratory fixed-bed catalytic reactor (FBCR) with catalytic oxidation of propene and toluene as model reactions. For better understanding of catalytic activity in a FBCR, the influence of operating parameters such as of platinum (Pt) loading, total gas flow rate, VOC concentration, and oxygen content were studied. The results showed that catalytic activity increases with increase in VOC concentration and a decrease in total gas flow rate. This displayed behaviour is instrumental to working at a low temperature region for complete oxidation of volatile organic compounds.
19
Vargas, Victor, Marie-Cecile Chalbot, Robert O'Brien, George Nikolich, David W. Dubois, Vic Etyemezian et Ilias G. Kavouras. « The effect of anthropogenic volatile organic compound sources on ozone in Boise, Idaho ». Environmental Chemistry 11, no 4 (2014) : 445. http://dx.doi.org/10.1071/en13150.
Texte intégralRésumé :
Environmental context Volatile organic compounds are precursors of ozone, a pollutant with adverse environmental effects. It is important to determine the associations between the various sources of volatile organic compounds and ozone levels because emission controls are based on sources. We estimated the contributions of specific sources of volatile organic compounds on ozone levels using both measurements and statistical models, and found that traffic is the largest source even in events when wildfire smoke is present. Abstract Here, we present the application of a tiered approach to apportion the contributions of volatile organic compound (VOC) sources on ozone (O3) concentrations. VOCs from acetylene to n-propylbenzene were measured at two sites at Boise, Idaho, using an online pneumatically focussed gas chromatography system. The mean 24-h concentrations of individual VOCs varied from 0.4ppbC (parts per billion carbon) for 1-butene to 23.2ppbC for m- and p-xylene. The VOC sources at the two monitoring sites were determined by positive matrix factorisation. They were attributed to: (i) liquefied petroleum and natural gas (LPG/NG) emissions; (ii) fugitive emissions of olefins from fuel and solvents; (iii) fugitive emissions of aromatic VOCs from area sources and (iv) vehicular emissions. Vehicle exhausts accounted for 36 to 45% of VOCs followed by LPG/NG and fugitive emissions of aromatic VOCs. Evaluation of photochemical changes showed that the four separate VOC sources were identified by PMF rather than different stages of photochemical processing of fresh emissions. The contributions of VOC sources on daily 8-h maximum O3 concentrations measured at seven locations in the metropolitan urban area were identified by regression analysis. The four VOC sources added, on average, 6.4 to 16.5 parts per billion by volume (ppbv) O3, whereas the unexplained (i.e. intercept) O3 was comparable to non-wildfire policy-relevant background O3 levels in the absence of all anthropogenic emissions of VOC precursors in North America for the region. Traffic was the most significant source influencing O3 levels contributing up to 32ppbv for days with O3 concentrations higher than 75ppbv.
20
Ciccioli, P., A. Cecinato, E. Brancaleoni, M. Frattoni, F. Bruner et M. Maione. « Occurrence of Oxygenated Volatile Organic Compounds (VOC) in Antarctica ». International Journal of Environmental Analytical Chemistry 62, no 3 (mars 1996) : 245–53. http://dx.doi.org/10.1080/03067319608028137.
Texte intégral
21
Molnár, Ágnes. « Estimation of volatile organic compounds (VOC) emission for Hungary ». Atmospheric Environment. Part A. General Topics 24, no 11 (1990) : 2855–60. http://dx.doi.org/10.1016/0960-1686(90)90173-k.
Texte intégral
22
Salman, Dahlia, Wadah Ibrahim, Amisha Kanabar, Abigail Joyce, Bo Zhao, Amisha Singapuri, Michael Wilde et al. « The variability of volatile organic compounds in the indoor air of clinical environments ». Journal of Breath Research 16, no 1 (2 décembre 2021) : 016005. http://dx.doi.org/10.1088/1752-7163/ac3565.
Texte intégralRésumé :
Abstract The development of clinical breath-analysis is confounded by the variability of background volatile organic compounds (VOCs). Reliable interpretation of clinical breath-analysis at individual, and cohort levels requires characterisation of clinical-VOC levels and exposures. Active-sampling with thermal-desorption/gas chromatography-mass spectrometry recorded and evaluated VOC concentrations in 245 samples of indoor air from three sites in a large National Health Service (NHS) provider trust in the UK over 27 months. Data deconvolution, alignment and clustering isolated 7344 features attributable to VOC and described the variability (composition and concentration) of respirable clinical VOC. 328 VOC were observed in more than 5% of the samples and 68 VOC appeared in more than 30% of samples. Common VOC were associated with exogenous and endogenous sources and 17 VOC were identified as seasonal differentiators. The presence of metabolites from the anaesthetic sevoflurane, and putative-disease biomarkers in room air, indicated that exhaled VOC were a source of background-pollution in clinical breath-testing activity. With the exception of solvents, and waxes associated with personal protective equipment (PPE), exhaled VOC concentrations above 3 µg m−3 are unlikely to arise from room air contamination, and in the absence of extensive survey-data, this level could be applied as a threshold for inclusion in studies, removing a potential environmental confounding-factor in developing breath-based diagnostics.
23
Tirillini, Bruno, et Filippo Maggi. « Volatile Organic Compounds of the Glandular Trichomes of Ocimum basilicum and Artifacts during the Distillation of the Leaves ». Applied Sciences 11, no 16 (9 août 2021) : 7312. http://dx.doi.org/10.3390/app11167312.
Texte intégralRésumé :
Focusing on volatile organic compounds (VOC) of Ocimum basilicum, this study aims to determine the chemical composition of VOC in secretory trichomes and compare it with that of essential oil obtained by hydrodistillation of leaves. The technique of extracting the content of glandular trichomes refers to the microneedle shuttle analysis. Hydrodistillation of fresh leaves was done with a Clevenger distiller (EO). The chemical compositions were determined by GC/FID and GC/MS. The head of the capitate trichomes does not contain volatile compounds. Fifty volatile compounds were detected in the EO, and twenty-four volatile compounds were detected in the VOC; the main components were eugenol (from 15.47 ± 1.05% to 41.89 ± 2.83%) and linalool (from 32.05 ± 2.57% to 28.99 ± 2.32%), respectively. During the distillation of the basil leaves 26 artifacts are formed. The composition of the essential oil of O. basilicum therefore depends not only on the plant but also on the method used to obtain it.
24
Kumeroa, Fern, Shanika Komahan, Svetla Sofkova-Bobcheva et Andrea Clavijo McCormick. « Characterization of the Volatile Profiles of Six Industrial Hemp (Cannabis sativa L.) Cultivars ». Agronomy 12, no 11 (27 octobre 2022) : 2651. http://dx.doi.org/10.3390/agronomy12112651.
Texte intégralRésumé :
Volatile organic compounds (VOCs) play an important role in plant ecology and can be useful in pest management. This work characterises, for the first time, the VOC emissions of six industrial hemp (Cannabis sativa L.) cultivars grown in New Zealand: CFX-2, CRS-1, Ferimon 12, Katani, Futura 75, and Finola. Volatiles emitted from flowers and foliage of eight-week-old plants were collected using a dynamic headspace sampling method and analysed using gas chromatography coupled to mass spectrometry. We assessed the effect of cultivar, sex (monoecious, male, and female), and site (i.e., two sites differing in soil types, maintained under irrigation and rain-fed conditions) on VOC emissions. Thirty-five volatile compounds were tentatively identified from the headspace samples of hemp plants, but none of the cultivars emitted all 35 compounds. β-Myrcene was the most abundant compound in most cultivars. Overall, there was a significant effect of sex, and the interaction of sex and cultivar on the volatile profiles, but no effect of site. Female plants typically emitted more volatiles than their male counterparts and monoecious cultivars. The main compounds driving the difference between cultivars and sexes were (Z)- and (E)-β-ocimene. We hypothesize that differences in emission emerged as a defence strategy to protect costly female flowers from herbivores (since C. sativa is wind pollinated), but this hypothesis needs further testing. We recommend additional studies exploring how biotic and abiotic factors influence hemp VOC emissions, changes in VOCs throughout the crop cycle, the role of VOCs in plant-insect interactions and their use in pest management.
25
Webber, M. D., J. D. Goodin, P. J. A. Fowlie, R. L. Hong-You et J. Legault. « Persistence of Volatile Organic Compounds in Sludge Treated Soils ». Water Quality Research Journal 32, no 3 (1 août 1997) : 579–98. http://dx.doi.org/10.2166/wqrj.1997.034.
Texte intégralRésumé :
Abstract Laboratory incubation studies were conducted to assess the persistence of ten volatile organic compounds (VOCs) in seven soils treated with 3% dw of anaer-obically digested municipal sludge. The VOCs were probable municipal sludge contaminants and the soils represented wide ranges of constituents likely to sorb organic compounds, e.g., organic carbon (1.3 to 12%) and clay (7 to 50%). The VOCs were spiked into soils at 50 mg kg-1 dw of soil, except for trichloro-ethylene and chloroform which were at 2.5 mg kg-1 dw. Three general patterns of VOC losses from soils were identified: (1) complete volatilization at room temperature within 24 h, (2) complete volatilization/degradation within 144 to 288 h, and (3) incomplete volatilization/degradation within 288 h. All VOC losses were consistent with first-order kinetics and indicated a combination of a rapid initial kinetic (0 to 4 h) followed by a slower kinetic. The slower kinetic was assumed to be more relevant to field VOC losses than the rapid kinetic, and first-order half-lives were calculated using the 4- to 288-h experimental data. The half-lives ranged from 5.5 to 1,926 h with a median value of 70 h, and generally increased with increasing boiling points of the VOCs and with increasing organic carbon contents of the soils. These laboratory findings indicate that VOCs in land-applied sludge are unlikely to represent a hazard to agriculture.
26
Zhou, You, et Bing Yan. « A responsive MOF nanocomposite for decoding volatile organic compounds ». Chemical Communications 52, no 11 (2016) : 2265–68. http://dx.doi.org/10.1039/c5cc09029f.
Texte intégralRésumé :
A molecular decoding platform, which recognizes aromatic VOCs with distinctly different 2D readouts, has been developed by a responsive luminescent MOF nanocomposite. The VOC recognition is based on an unprecedented dual-readout orthogonal identification scheme.
27
Chiemchaisri, Wilai, Chettiyappan Visvanathan et Shing Wu Jy. « Effects of trace volatile organic compounds on methane oxidation ». Brazilian Archives of Biology and Technology 44, no 2 (juin 2001) : 135–40. http://dx.doi.org/10.1590/s1516-89132001000200005.
Texte intégralRésumé :
The effects of volatile organic compounds (VOCs) on methane oxidation in landfill cover soils were examined. The batch experiments were conducted using single and mixed VOCs, such as, dichloromethane (DCM), trichloroethylene (TCE), tetrachloroethylene (PCE), and benzene. The results from all combinations showed a decrease in methane oxidation rate with increase in VOC concentrations. Moreover, inhibition effects of TCE and DCM were found higher than benzene and PCE. The reduction of methane oxidation by benzene and PCE could be attributed to the toxicity effect, whereas TCE and DCM were found to exhibit the competitive-inhibition effect. When the soil was mixed with DCM, no methane oxidation was found. Damage to the cell’s internal membrane was found in a methanotrophic culture exposed to VOC gases which is the attachment site of a key enzyme needed for methane oxidation
28
Chen, Jing, Neng Zhu et Xin Li Shi. « Measurements of VOC Emission from Polyurethane Varnish for Interior Use ». Applied Mechanics and Materials 193-194 (août 2012) : 345–50. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.345.
Texte intégralRésumé :
The emission of volatile organic compounds (VOC) from single-component polyurethane varnish applied to beech plywood at two temperatures (33°C, 43°C) has been investigated in a small environmental chamber. The experimental results indicated that the concentration of each compound, as well as the total volatile organic compounds (TVOC), increased rapidly after the start of experiment, and attained their maximum values at 0.5 h. The concentrations decreased rapidly after 0.5 h, and then decreased more slowly in the period 2 – 24 h. The concentrations of isopropylbenzene, n-decane and TVOC were higher in the 43°C test than in the 33°C test within the first 1.5 h. The influences of temperature on the concentrations of these pollutants were different during the period 1.5 – 24 h.
29
el Manouni el Hassani, Sofia, Hendrik Niemarkt, Hager Said, Daniel Berkhout, Anton van Kaam, Richard van Lingen, Marc Benninga, Nanne de Boer et Tim de Meij. « Fecal Volatile Organic Compounds in Preterm Infants Are Influenced by Enteral Feeding Composition ». Sensors 18, no 9 (11 septembre 2018) : 3037. http://dx.doi.org/10.3390/s18093037.
Texte intégralRésumé :
Fecal volatile organic compound (VOC) analysis has shown great potential as a noninvasive diagnostic biomarker for a variety of diseases. Before clinical implementation, the factors influencing the outcome of VOC analysis need to be assessed. Recent studies found that the sampling conditions can influence the outcome of VOC analysis. However, the dietary influences remains unknown, especially in (preterm) infants. Therefore, we assessed the effects of feeding composition on fecal VOC patterns of preterm infants (born at <30 weeks gestation). Two subgroups were defined: (1) daily intake >75% breastmilk (BM) feeding and (2) daily intake >75% formula milk (FM) feeding. Fecal samples, which were collected at 7, 14 and 21 days postnatally, were analyzed by an electronic nose device (Cyranose 320®). In total, 30 preterm infants were included (15 FM, 15 BM). No differences in the fecal VOC patterns were observed at the three predefined time-points. Combining the fecal VOC profiles of these time-points resulted in a statistically significant difference between the two subgroups although this discriminative accuracy was only modest (AUC [95% CI]; p-value; sensitivity; and specificity of 0.64 [0.51–0.77]; 0.04; 68%; and 51%, respectively). Our results suggest that the influence of enteral feeding on the outcome of fecal VOC analysis cannot be ignored in this population. Furthermore, in both subgroups, the fecal VOC patterns showed a stable longitudinal course within the first month of life.
30
Fiorenza, Roberto. « Bimetallic Catalysts for Volatile Organic Compound Oxidation ». Catalysts 10, no 6 (12 juin 2020) : 661. http://dx.doi.org/10.3390/catal10060661.
Texte intégralRésumé :
In recent years, the impending necessity to improve the quality of outdoor and indoor air has produced a constant increase of investigations in the methodologies to remove and/or to decrease the emission of volatile organic compounds (VOCs). Among the various strategies for VOC elimination, catalytic oxidation and recently photocatalytic oxidation are regarded as some of the most promising technologies for VOC total oxidation from urban and industrial waste streams. This work is focused on bimetallic supported catalysts, investigating systematically the progress and developments in the design of these materials. In particular, we highlight their advantages compared to those of their monometallic counterparts in terms of catalytic performance and physicochemical properties (catalytic stability and reusability). The formation of a synergistic effect between the two metals is the key feature of these particular catalysts. This review examines the state-of-the-art of a peculiar sector (the bimetallic systems) belonging to a wide area (i.e., the several catalysts used for VOC removal) with the aim to contribute to further increase the knowledge of the catalytic materials for VOC removal, stressing the promising potential applications of the bimetallic catalysts in the air purification.
31
Bitas, Vasileios, Hye-Seon Kim, Joan W. Bennett et Seogchan Kang. « Sniffing on Microbes : Diverse Roles of Microbial Volatile Organic Compounds in Plant Health ». Molecular Plant-Microbe Interactions® 26, no 8 (août 2013) : 835–43. http://dx.doi.org/10.1094/mpmi-10-12-0249-cr.
Texte intégralRésumé :
Secreted proteins and metabolites play diverse and critical roles in organismal and organism–environment interactions. Volatile organic compounds (VOC) can travel far from the point of production through the atmosphere, porous soils, and liquid, making them ideal info-chemicals for mediating both short- and long-distance intercellular and organismal interactions. Critical ecological roles for animal- and plant-derived VOC in directing animal behaviors and for VOC as a language for plant-to-plant communication and regulators of various physiological processes have been well documented. Similarly, microbial VOC appear to be involved in antagonism, mutualism, intra- and interspecies regulation of cellular and developmental processes, and modification of their surrounding environments. However, the available knowledge of how microbial VOC affect other organisms is very limited. Evidence supporting diverse roles of microbial VOC with the focus on their impact on plant health is reviewed here. Given the vast diversity of microbes in nature and the critical importance of microbial communities associated with plants for their ecology and fitness, systematic exploration of microbial VOC and characterization of their biological functions and ecological roles will likely uncover novel mechanisms for controlling diverse biological processes critical to plant health and will also offer tangible practical benefits in addressing agricultural and environmental problems.
32
Rondanelli, Mariangela, Federica Perdoni, Vittoria Infantino, Milena Anna Faliva, Gabriella Peroni, Giancarlo Iannello, Mara Nichetti, Tariq A. Alalwan, Simone Perna et Clementina Cocuzza. « Volatile Organic Compounds as Biomarkers of Gastrointestinal Diseases and Nutritional Status ». Journal of Analytical Methods in Chemistry 2019 (10 septembre 2019) : 1–14. http://dx.doi.org/10.1155/2019/7247802.
Texte intégralRésumé :
Purpose. The purpose of this review was to identify the best solution for rapid and noninvasive diagnosis and long-term monitoring of patients affected by inflammatory gastrointestinal diseases, colon and gastric cancer, obesity in correlation to diet, and breast milk to evaluate exposure to VOCs in women and infants. Methods. This review included 20 previously published eligible studies. VOC analysis has allowed us to highlight differences in lifestyles, intestinal microbiota, and metabolism. New innovative methods have been described that allow the detection and quantification of a broad spectrum of metabolites present in exhaled breath even at very low levels, some of which have been shown to be indicators of pathological conditions. Results. Five studies were analyzed that involved VOC analysis in relation to type of diet. All of them showed that the type of diet can have an impact on metabolites excreted and therefore can be a useful tool in the nutritional studies related to metabolism and health and disease status. Two studies concerned VOC analysis in inflammatory bowel diseases, and the results showed that VOCs can distinguish active disease from remission; VOC profile is clearly different in patients. In particular, C15H30 1-pentadecene, 3-methyl-1-butanal, octane, acetic acid, alpha-pinene, and m-cymene are elevated in active ulcerative colitis. Four studies examined VOCs in gastric and colorectal tumors showing a change in metabolic biomarkers of cancer patients compared to the control group. Finally, the study of VOCs in breast milk has improved the understanding of the potential health risks of exposure of children to chemical pollutants. Conclusions. VOC analysis allowed to highlight differences in behavior, lifestyle, and metabolism of individuals. Analytical methods are continuously developed to allow for better detection and quantification of metabolites, thus enabling the detection of a broader spectrum of pathophysiology and disease biomarkers.
33
Pui, Wee Kong, Rozita Yusoff et Mohamed Kheireddine Aroua. « A review on activated carbon adsorption for volatile organic compounds (VOCs) ». Reviews in Chemical Engineering 35, no 5 (26 juillet 2019) : 649–68. http://dx.doi.org/10.1515/revce-2017-0057.
Texte intégralRésumé :
Abstract A number of control methods have been adopted for the removal of hazardous volatile organic compounds (VOCs) from gas streams, particularly adsorption processes which are considered more prominent in terms of feasibility, effectiveness as well as cost competence compared to other methods. In this study, most of the activated-carbon-based adsorbents are critically reviewed in terms of their advantages and limitations for VOC gas adsorption. The choice of adsorbent and process parameters depends mainly on the type of VOC used, its chemical and structural properties, in addition to the adsorbent’s characteristics. The review discusses in detail the application of fixed-bed adsorption systems. A computational simulation study using quantum-chemical conductor like screening model for real solvents is included in this review which determines the efficiency in describing and predicting the adsorption technique required for each process. This review offers a comprehensive discussion of the VOC adsorption techniques and their implementation for different applications.
34
Wu, Shu Yun, Zeng Feng Yan, Jun Gang Dong et Huan Huan Liu. « Research of the Distribution of Volatile Organic Compounds (VOC) in Print Shops in Xi’an ». Applied Mechanics and Materials 209-211 (octobre 2012) : 1560–65. http://dx.doi.org/10.4028/www.scientific.net/amm.209-211.1560.
Texte intégralRésumé :
Volatile organic compounds (VOCs) are major constituents of the indoor air pollutants. The indoor air quality has caused wide concern for VOCs may affect human health in many ways. The VOCs in general rooms volatilize from building materials, furniture and so on. In print shops the print equipment and materials may produce a large amount of VOCs that may affect the health of the long-term print shop workers. The author has measured the VOC content and the air indexes in a seventy square-meter print shop in Xi’an with comprehensive functions, then, evaluated the pollution and proposed the preventions of the VOC content in print shops.
35
Lim, M., et A. R. Lea-Langton. « Simulation of ozonolysis of volatile organic compounds : Effect on flue gas composition ». IOP Conference Series : Materials Science and Engineering 1195, no 1 (1 octobre 2021) : 012012. http://dx.doi.org/10.1088/1757-899x/1195/1/012012.
Texte intégralRésumé :
Abstract This study shows that the reaction of ozone with various volatile organic compounds (VOC) yields different flue gas composition in terms of the carbon dioxide, oxygen and moisture contents. Steam production and thermal output requirements from a combustion system (i.e., a boiler) may dictate the range of operating conditions, such as the air to fuel mass flow rates. To improve the combustion efficiency in these operating conditions, low temperature plasmas have been used to ionize air and generate ozone as an oxidant for ozonolysis with the VOC. Therefore, this study simulates the reaction mechanism of the ozonolysis of VOC and the effect on the flue gas composition, which affects the combustion efficiency. Simulation results show that residual oxygen in the flue gas reduces, reducing the excess air. Thus, the corresponding efficiency loss through dry flue gas would be reduced. Literature data shows that emissions of alkanes, alkynes and alkenes per unit mass of solid fuel is evident for both coal and biomass, and thus ozonolysis of these VOC would reduce the excess air, improving the combustion efficiency.
36
Zhang, Hong Hua, Shao Peng Wu, Ling Pang, Kim Jenkins, Man Yu et Pei Qiang Cui. « Grey System Theoretical Analysis on the Influence of Volatile Organic Compounds Emission from Asphalt on its Performance ». Advanced Materials Research 753-755 (août 2013) : 481–85. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.481.
Texte intégralRésumé :
Light components in the asphalt can volatilize under the circumstances of high temperature or long-term service process, leading to the deteriorating of the asphalt pavement. This paper tried to discuss the influences of volatile organic compounds (VOC) emission from the asphalt on physical properties in the high temperature (at 180) by grey system theory. Both Heat and Vacuum environment were monitored as the emission conditions and the emission temperature was 180°C, physical properties of asphalt, released and unreleased were analyzed. Basic tests, including mass change, chemical compositions, penetration and soften point, were used to compare the influences of VOC emission on the asphalts performances. Meanwhile, grey system theory was used to investigate the sequent performances influenced by VOC emission. Results show that physical properties and four generic components of the asphalts are affected obviously in these two emission conditions, and the oxygen may promote VOC emission from the asphalt. In additional, the greatest factor associating with VOC emission is light components in the asphalt.
37
Umarani, R., M. Bhaskaran, C. Vanitha et M. Tilak. « Fingerprinting of volatile organic compounds for quick assessment of vigour status of seeds ». Seed Science Research 30, no 2 (juin 2020) : 112–21. http://dx.doi.org/10.1017/s0960258520000252.
Texte intégralRésumé :
AbstractSeed is a fertilized mature ovule, which possesses an embryonic plant. When the dry, mature seeds are subjected to imbibition, they release a wide range of organic substances, which include low molecular weight carbonyl compounds (gases and volatiles) and water-soluble organic substances (enzymes and polysaccharides). The volatile organic compounds (VOCs) are molecules of low molecular weight (300 g mol−1) and high vapour pressure (0.01 kPa at 20°C) and include diverse chemical compounds. The nature and emission kinetics of volatiles produced from seeds vary, depending on the moisture content of the seeds. Orthodox seeds stored at ‘low seed moisture content’ undergo seed deterioration, predominantly due to lipid peroxidation, initiated by autoxidation or enzymatic oxidation of unsaturated or polyunsaturated fatty acids. This peroxidation leads to emission of volatile compounds. The quantity of VOCs emitted is positively correlated with the advancement of seed deterioration. With respect to the seed germination process, exposure of seeds to ‘high moisture conditions’ leads to increased respiration, triggers glycolysis and mobilization of storage reserves, resulting in the emission of volatile metabolic products. The quantity of VOCs emitted on commencement of metabolic activity in germinating seeds depends on (1) vigour status and (2) amount of storage reserves. Since it has been established that there is a significant difference between high and low vigour seeds with respect to quantity and profile of VOCs emitted, there is great potential for utilizing the VOC profile to obtain a quick and reproducible test of vigour status of crop seeds. In order to harness the VOC profile for quick assessment of vigour status of seeds, research has to be taken up to develop standard protocols for fingerprinting of VOCs for the purpose of seed vigour assessment and to fix the standard volatile biomarker(s) specific to crop and vigour status of seeds.
38
Murphy, J. G., D. E. Oram et C. E. Reeves. « Measurements of volatile organic compounds over West Africa ». Atmospheric Chemistry and Physics 10, no 12 (16 juin 2010) : 5281–94. http://dx.doi.org/10.5194/acp-10-5281-2010.
Texte intégralRésumé :
Abstract. In this paper we describe measurements of volatile organic compounds (VOC) made using a Proton Transfer Reaction Mass Spectrometer (PTR-MS) aboard the UK Facility for Atmospheric Airborne Measurements during the African Monsoon Multidisciplinary Analyses (AMMA) campaign. Observations were made during approximately 85 h of flying time between 17 July and 17 August 2006, above an area between 4° N and 18° N and 3° W and 4° E, encompassing ocean, mosaic forest, and the Sahel desert. High time resolution observations of counts at mass to charge (m/z) ratios of 42, 59, 69, 71, and 79 were used to calculate mixing ratios of acetonitrile, acetone, isoprene, the sum of methyl vinyl ketone and methacrolein, and benzene respectively using laboratory-derived humidity-dependent calibration factors. Strong spatial associations between vegetation and isoprene and its oxidation products were observed in the boundary layer, consistent with biogenic emissions followed by rapid atmospheric oxidation. Acetonitrile, benzene, and acetone were all enhanced in airmasses which had been heavily influenced by biomass burning. Benzene and acetone were also elevated in airmasses with urban influence from cities such as Lagos, Cotonou, and Niamey. The observations provide evidence that both deep convection and mixing associated with fair-weather cumulus were responsible for vertical redistribution of VOC emitted from the surface. Profiles over the ocean showed a depletion of acetone in the marine boundary layer, but no significant decrease for acetonitrile.
39
Zhu, Xiao Dong, Jun Shen et Yu Liu. « Removal of Formaldehyde and Volatile Organic Compounds from Particleboards by Air-Cleaning Materials ». Advanced Materials Research 113-116 (juin 2010) : 1870–73. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.1870.
Texte intégralRésumé :
The removal efficiencies of 4 air-cleaning materials on formaldehyde and VOC emissions from particleboards were examined in this paper. The effect of activated carbon and photo catalyst on formaldehyde and VOC emissions removal was notable in short time. The effect of scavenger was obviously on formaldehyde removal for its synthetic mechanism. And the impact of bioenzyme on formaldehyde and VOC emissions from particleboards is dependent on the test conditions and it shows no impact on emissions in this experiment.
40
Yamaguchi, Takeo. « Separation and Recovery of Volatile Organic Compounds（VOC）by Membranes ». MEMBRANE 31, no 1 (2006) : 30–31. http://dx.doi.org/10.5360/membrane.31.30.
Texte intégral
41
Ozdemir, Celalettin, Sukru Dursun et Nejdet Sen. « Methane Production from Anaerobic Treatment of Volatile Organic Compounds (Voc) ». Energy Exploration & ; Exploitation 24, no 4 (août 2006) : 259–70. http://dx.doi.org/10.1260/014459806779398767.
Texte intégral
42
Czajka, Magdalena, Beata Fabisiak et Ewa Fabisiak. « Emission of Volatile Organic Compounds from Heartwood and Sapwood of Selected Coniferous Species ». Forests 11, no 1 (11 janvier 2020) : 92. http://dx.doi.org/10.3390/f11010092.
Texte intégralRésumé :
The qualitative and quantitative composition of volatile organic compounds (VOC) emitted from furnishings from solid wood and all kinds of wood derivative materials depends on many factors, of which the most important is the wood species. The intraspecies and interspecies differences in VOC emission result from the differences in the chemical composition and anatomical structure of heartwood and sapwood of different species. VOC composition analysis was performed separately for heartwood and sapwood of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and European larch (Larix decidua Mill.) trees. The studies were conducted in a glass climatic chamber of 0.025 m3, equipped with a system for the monitoring and control of climatic conditions. Samples of air for analyses were collected after 3, 7, 14 and 28 days of exposure. The results provided evidence for interspecies and intraspecies differences in the qualitative and quantitative compositions of VOC. The concentration of total VOC (TVOC) released from heartwood of Scots pine was higher than that released from sapwood. For European larch and Norway spruce, the opposite relations were observed. The VOC emission from Scots pine heartwood was about 17 times higher than the emission from European larch and Norway spruce heartwood. The differences in TVOC emitted from the sapwood of samples from different species were smaller. For each of the species, the highest percentage contribution to TVOC was made by terpenes. The second highest percentage contribution in TVOC was made by compounds containing a carbonyl group, mainly aldehydes, while aromatic compounds made the third highest contribution.
43
Brüggemann, Martin, Nathalie Hayeck, Chloé Bonnineau, Stéphane Pesce, Peter A. Alpert, Sébastien Perrier, Christoph Zuth, Thorsten Hoffmann, Jianmin Chen et Christian George. « Interfacial photochemistry of biogenic surfactants : a major source of abiotic volatile organic compounds ». Faraday Discussions 200 (2017) : 59–74. http://dx.doi.org/10.1039/c7fd00022g.
Texte intégralRésumé :
Films of biogenic compounds exposed to the atmosphere are ubiquitously found on the surfaces of cloud droplets, aerosol particles, buildings, plants, soils and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to in bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants and VOC production. In particular, irradiation of samples containing solely biofilm cells without matrix components exhibited the strongest VOC production upon irradiation. In agreement with previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC productionviaperoxy radical chemistry. Up to now, such VOC emissions were directly accounted to high biological activity in surface waters. However, the results obtained suggest that abiotic photochemistry can lead to similar emissions into the atmosphere, especially in less biologically-active regions. Furthermore, chamber experiments suggest that oxidation (O3/OH radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth’s radiation budget.
44
Kohl, Lukas, Markku Koskinen, Kaisa Rissanen, Iikka Haikarainen, Tatu Polvinen, Heidi Hellén et Mari Pihlatie. « Technical note : Interferences of volatile organic compounds (VOCs) on methane concentration measurements ». Biogeosciences 16, no 17 (4 septembre 2019) : 3319–32. http://dx.doi.org/10.5194/bg-16-3319-2019.
Texte intégralRésumé :
Abstract. Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes in the mixing ratio of CH4 that coincide with much larger changes in the mixing ratio of volatile organic compounds (VOCs). Here, we assessed whether 11 commonly occurring VOCs (e.g. methanol, α- and β-pinene, Δ3-carene) interfered with the quantitation of CH4 by five laser-absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed minimal interference with laser-based analysers and underlined the importance of identifying and compensating for interferences with FTIR instruments. When VOCs were not included in the spectral library, they exerted a strong bias on FTIR-based instruments (64–1800 ppbv apparent CH4 ppmv−1 VOC). Minor (0.7–126 ppbv ppmv−1) interference with FTIR-based measurements were also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (<20 ppbv ppmv−1) and transient (< 1 min) VOC interferences on laser-absorption spectroscopy-based analysers. Overall, our results demonstrate that VOC interferences have only minor effects on CH4 flux measurements in soil chambers, but may severely impact stem and shoot flux measurements. Laser-absorption-based instruments are better suited for quantifying CH4 fluxes from plant leaves and stems than FTIR-based instruments; however, significant interferences in shoot chamber measurements could not be excluded for any of the tested instruments. Our results furthermore showed that FTIR can precisely quantify VOC mixing ratios and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).
45
Heinrich-Ramm, R., M. Jakubowski, B. Heinzow, J. Molin Christensen, E. Olsen et O. Hertel. « Biological monitoring for exposure to volatile organic compounds (VOCs) (IUPAC Recommendations 2000) ». Pure and Applied Chemistry 72, no 3 (1 janvier 2000) : 385–436. http://dx.doi.org/10.1351/pac200072030385.
Texte intégralRésumé :
This paper deals with the appropriate application of biological monitoring (BM) for exposure to volatile organic compounds (VOCs). Sampling guidelines, approved analytical procedures, quality control systems, detailed aspects for the interpretation of biomonitoring data, a compilation of international biological action values for VOC exposure at the workplace (e.g., BAT, BEI®), and state of the art reference values are outlined or referred to in this review for recommendation as guidelines for health professionals in occupational and environmental settings.VOCs are frequently encountered at the workplace, in daily routines and widely used consumer products. They cover a broad spectrum of chemical classes with different physicochemical and biological properties. Inhalation is a prominent route of exposure due to their volatility but many VOCs can quite readily be absorbed through the skin. BM allows assessment of the integrated exposure by different routes including inhalation and concomitant dermal and oral uptake—a helpful tool for relating exposure to body burden and possible health effects. Because of the different toxicological profiles of VOCs, no uniform approach for BM can be recommended. VOCs in blood and urinary VOC metabolites are most often applied for BM. Limit values for workplace exposure have been established for many VOCs. In this field, profound analytical methodology and extensive experience exist in numerous international scientific laboratories for reliable routine application. Contamination and loss of VOCs during specimen collection, storage and sample treatment, and applied calibration procedure are the most important uncertainties for analytical quantification of VOCs in blood. For interpretation of the analytical results appropriate time of sampling, according to toxicokinetics of the compound, is crucial due to VOC elimination with short but differing biological half-lives. Lifestyle factors (such as smoking habits, alcohol consumption, and dietary habits), workload, personal working habits, exposure to VOC mixtures and endogeous factors (as genetic polymorphism for VOC metabolizing enzymes, body mass) contribute to BM results and have to be considered in detail. Future analytical work should focus on the improvement of analytical methodology of VOC determination in body fluids at low-level environmental exposure and evaluation of corresponding reference intervals.
46
Fisher, R. M., R. J. Barczak, J. P. Alvarez Gaitan, N. Le-Minh et R. M. Stuetz. « Odorous volatile organic compound (VOC) emissions from ageing anaerobically stabilised biosolids ». Water Science and Technology 75, no 7 (20 janvier 2017) : 1617–24. http://dx.doi.org/10.2166/wst.2017.030.
Texte intégralRésumé :
Opportunities for the beneficial re-use of biosolids are limited by nuisance odour emissions. Volatile organic compounds (VOCs) from anaerobically stabilised biosolids were measured to identify compounds that could contribute to the overall odour character of nuisance emissions. Flux hood sampling and chemical analysis were used to identify VOCs emitted from biosolids as they were stored in ambient conditions. Compounds emitted varied as the biosolid cakes were stored for a period of 50 days. VOCs detected in the biosolids are likely to occur from catchment sources as well as abiotic and biotic generation in the wastewater processing and the biosolids as they are stored. Odour activity values (OAVs) were used to compare odorants. Trimethylamine was the only VOC detected that exceeded the sulfur compounds in terms of OAVs. Other compounds such as limonene, ethyl methyl benzene and acetic acid were detected at concentrations exceeding their olfactory detection limits, however at lower OAVs than sulfur compounds.
47
McFarlane, Michael, Ramesh P. Arasaradnam, Beryl Reed, Emma Daulton, Alfian Wicaksono, Heena Tyagi, James A. Covington et Chuka Nwokolo. « Minimal Gluten Exposure Alters Urinary Volatile Organic Compounds in Stable Coeliac Disease ». Sensors 22, no 3 (8 février 2022) : 1290. http://dx.doi.org/10.3390/s22031290.
Texte intégralRésumé :
Coeliac disease (CD) patients are distinguishable from healthy individuals via urinary volatile organic compounds (VOCs) analysis. We exposed 20 stable CD patients on gluten-free diet (GFDs) to a 14-day, 3 g/day gluten challenge (GCh), and assessed urinary VOC changes. A control cohort of 20 patients continued on GFD. Urine samples from Days 0, 7, 14, 28 and 56 were analysed using Lonestar FAIMS and Markes Gas Chromatography–Time of Flight–Mass Spectrometer (GC-TOF-MS). VOC signatures on D (day) 7–56 were compared with D0. Statistical analysis was performed using R. In GCh patients, FAIMS revealed significant VOC differences for all time points compared to D0. GC-TOF-MS revealed significant changes at D7 and D14 only. In control samples, FAIMS revealed significant differences at D7 only. GC-TOF-MS detected no significant differences. Chemical analysis via GC-MS-TOF revealed 12 chemicals with significantly altered intensities at D7 vs. D0 for GCh patients. The alterations persisted for six chemicals at D14 and one (N-methyltaurine) remained altered after D14. This low-dose, short-duration challenge was well tolerated. FAIMS and GC-TOF-MS detected VOC signature changes in CD patients when undergoing a minimal GCh. These findings suggest urinary VOCs could have a role in monitoring dietary compliance in CD patients.
48
Ran, Jinjun, Marianthi-Anna Kioumourtzoglou, Shengzhi Sun, Lefei Han, Shi Zhao, Wei Zhu, Jinhui Li et Linwei Tian. « Source-Specific Volatile Organic Compounds and Emergency Hospital Admissions for Cardiorespiratory Diseases ». International Journal of Environmental Research and Public Health 17, no 17 (27 août 2020) : 6210. http://dx.doi.org/10.3390/ijerph17176210.
Texte intégralRésumé :
Knowledge gaps remain regarding the cardiorespiratory impacts of ambient volatile organic compounds (VOCs) for the general population. This study identified contributing sources to ambient VOCs and estimated the short-term effects of VOC apportioned sources on daily emergency hospital admissions for cardiorespiratory diseases in Hong Kong from 2011 to 2014. We estimated VOC source contributions using fourteen organic chemicals by positive matrix factorization. Then, we examined the associations between the short-term exposure to VOC apportioned sources and emergency hospital admissions for cause-specific cardiorespiratory diseases using generalized additive models with polynomial distributed lag models while controlling for meteorological and co-pollutant confounders. We identified six VOC sources: gasoline emissions, liquefied petroleum gas (LPG) usage, aged VOCs, architectural paints, household products, and biogenic emissions. We found that increased emergency hospital admissions for chronic obstructive pulmonary disease were positively linked to ambient VOCs from gasoline emissions (excess risk (ER%): 2.1%; 95% CI: 0.9% to 3.4%), architectural paints (ER%: 1.5%; 95% CI: 0.2% to 2.9%), and household products (ER%: 1.5%; 95% CI: 0.2% to 2.8%), but negatively associated with biogenic VOCs (ER%: −6.6%; 95% CI: −10.4% to −2.5%). Increased congestive heart failure admissions were positively related to VOCs from architectural paints and household products in cold seasons. This study suggested that source-specific VOCs might trigger the exacerbation of cardiorespiratory diseases.
49
Vasagiri, Suresh, Rajesh Kumar Burra, Jyothi Vankara et M. S. Pradeep Kumar Patnaik. « A survey of MEMS cantilever applications in determining volatile organic compounds ». AIP Advances 12, no 3 (1 mars 2022) : 030701. http://dx.doi.org/10.1063/5.0075034.
Texte intégralRésumé :
Recently, microelectromechanical system (MEMS) cantilevers have received significant interest in the domain of Volatile Organic Compounds (VOCs). An analysis of MEMS cantilevers in VOCs is presented in this Review. It examines the different forms of sensors used to detect VOCs. It goes into the conditions that influence MEMS and the strategies used for VOC sensing. It examines research on MEMS cantilevers and other VOC sensing and detection techniques. It shows how MEMS can be used to detect VOCs. Moreover, it presents a comparative study based on the objectives, types of sensors employed, merits, and shortcomings of existing works. This Review intends to explore MEMS cantilevers in VOCs for supporting further research and applications.
50
Pedrini, Alessandro, Angelo Maspero, Silvia Bracco, Angelina Comotti, Simona Galli, Luciano Marchiò, Luca Nardo et al. « Synthesis, crystal structure, and optical properties of fluorinated poly(pyrazole) ligands and in silico assessment of their affinity for volatile organic compounds ». New Journal of Chemistry 44, no 16 (2020) : 6443–55. http://dx.doi.org/10.1039/d0nj00259c.
Texte intégralRésumé :
Increasing fluorination of an organic ligand forming porous coordination polymers results in enhanced affinity for volatile organic compounds (VOCs) without affecting the fluorescence properties, thus opening new perspectives for VOC sensing.