The FLEC® has been validated and used in research for many years.
Below is a publication list of journal articles, abstracts, poster or oral presentations where the FLEC or CHEMATEC’s other products have been in focus.
If you have anything that can be added to the list, we encourage you to contact CHEMATEC.
Shin, Seung H; Jo, Wan K
In: Chemosphere, 89 (5), pp. 569 - 578, 2012, ISSN: 0045-6535.
The present study investigated the indoor concentrations of selected volatile organic compounds (VOCs) and formaldehyde and their indoor emission characteristics in newly-built apartments at the pre-occupancy stage. In total, 107 apartments were surveyed for indoor and outdoor VOC concentrations in two metropolitan cities and one rural area in Korea. A mass balanced model was used to estimate surface area-specific emission rates of individual VOCs and formaldehyde. Seven (benzene, ethyl benzene, toluene, m,p-xylene, o-xylene, n-hexane, and n-heptane) of 40 target compounds were detectable in all indoor air samples, whereas the first five were detected in all outdoor air samples. Formaldehyde was also predominant in the indoor air samples, with a high detection frequency of 96%. The indoor concentrations were significantly higher than the outdoor concentrations for aromatics, alcohols, terpenes, and ketones. However, six halogenated VOCs exhibited similar concentrations for indoor and outdoor air samples, suggesting that they are not major components emitted from building materials. It was also suggested that a certain portion of the apartments surveyed were constructed by not following the Korean Ministry of Environment guidelines for formaldehyde emissions. Toluene exhibited the highest emission rate with a median value of 138μgm−2h−1. The target compounds with median emission rates greater than 20μgm−2h−1 were toluene, 1-propanol, formaldehyde, and 2-butanone. The wood panels/vinyl floor coverings were the largest indoor pollutant source, followed by floorings, wall coverings, adhesives, and paints. The wood panels/vinyl floor coverings contributed nearly three times more to indoor VOC concentrations than paints.
Min, Jingchun; Hu, Teng; Song, Yaozu
In: Journal of Membrane Science, 367 (1), pp. 174 - 181, 2011, ISSN: 0376-7388.
Experimental and numerical combined studies were carried out to investigate the effects of membrane properties and operating condition on water vapor (moisture) permeation through membranes. Experiments were conducted with water vapor transferring from a highly to a less humid air across membrane due to the water vapor concentration difference between the two sides of membrane, and numerical simulations were performed to simulate such process. The transmembrane moisture transfer was characterized using the moisture transfer resistance through membrane as well as the total moisture resistance, which include the membrane resistance and the boundary layer resistance on the two sides of membrane. The uniqueness of this research was a systematic examination of the effects of various membrane parameters and operating condition on the moisture permeation through membranes by combining the experiments and simulations. Tests were done on two membranes including the PVDF and PES membranes. The moisture diffusivities in these membranes were determined by comparing the experimental and numerical total moisture resistances. The results show that the moisture diffusivities in the PVDF and PES membranes are in the order of 10−6kgm−1s−1, with the PVDF yielding a larger diffusivity than the PES membrane. The moisture diffusivity in membrane, the maximum water uptake of membrane, and the sorption constant of membrane all have significant effects on the membrane resistance, with a high diffusivity, a large water uptake, and a proper sorption constant leading to a small membrane resistance, while the effects of the air entering humidity and airflow rate on the membrane resistance are dependent on the sorption constant. These results may help for the selection of the membrane materials.
Schossler, Patrícia; Schripp, Tobias; Salthammer, Tunga; Bahadir, Müfit
In: Science of The Total Environment, 409 (19), pp. 4031 - 4038, 2011, ISSN: 0048-9697.
The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called “alternative” plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p0 and octanol–air partitioning coefficients KOA were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients Kp and fractions can widely differ due to the uncertainty in the predicted p0 and KOA values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a microchamber as is shown for di-n-butyl phthalate (DnBP), di(2-ethylhexyl) adipate(DEHA), tri(octyl) trimellitate (TOTM) and DEHP.
Methodologies for Assessing Bioaerosol Exposures Incollection
In: Nriagu, J O (Ed.): Encyclopedia of Environmental Health, pp. 722 - 730, Elsevier, Burlington, 2011, ISBN: 978-0-444-52272-6.
Bioaerosols include viruses, bacteria, fungi, pollen, and their fragments as well as animal allergens. Bioaerosol exposure is common in indoor and outdoor environments and may cause infections, allergies, irritation, and toxic effects. The size of biological particles varies widely, from nanoscale (virions and microbial fragments) to approximately 100μm (pollen grains). The same physical principles that are applied to nonbiological particles can be applied to bioaerosol sampling in terms of sampling efficiency of a given particle size range. When sampling bioaerosols for exposure assessment purposes, one has to consider what biological property would be the most relevant measure for the health effect in question. Cultivation and microscopic counting are traditional analytical methods, but recently several new methods are emerging that are based on chemical, biological, or immunochemical analysis of bioaerosol components. Data interpretation is based on comparisons of results in target and reference areas or populations. When comparing data with previously published values, only results that are obtained using the same methodology should be directly compared.
Wang, Rong; Zhu, Jiping; Rastan, Soheil; Haghighat, Fariborz
In: Journal of Hazardous Materials, 192 (3), pp. 1026 - 1032, 2011, ISSN: 0304-3894.
A new approach for estimating chemical emissions from wet products has been developed. The concept of such approach is that emission rates can be estimated from the amount of target chemicals in the product as a function of evaporation time. Samples were placed under a laboratory fume hood under controlled conditions (surface air velocity and temperature). Weight losses of the product were monitored and residuals at different time intervals were chemically analyzed. Emission factors of the target chemicals were then calculated based on the weight losses and residual levels of the chemicals. To demonstrate the applicability of this approach, two wet products with very different physical characteristics, one liquid and one paste-like viscous fluid, were chosen. Emissions of two principle chemicals in the products, decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were measured. The influences of initial sample weight, surface air velocity, and temperature were investigated. The calculated emission profiles were compared with those obtained from the chamber method. The described approach could be used as an alternative screening method for emission tests of wet products, especially for compounds with low vapour pressure when sink effect poses serious challenge in traditional chamber-based emission tests.
An, Jae-Yoon; Kim, Sumin; Kim, Hyun-Joong
In: Journal of Hazardous Materials, 187 (1), pp. 44 - 51, 2011, ISSN: 0304-3894.
Formaldehyde was measured with a desiccator, a 20L chamber and the FLEC method. The formaldehyde emission rate from laminate was the highest at 32°C using the desiccator, which then decreased with time. The formaldehyde emission using the 20L small chamber and FLEC showed a similar tendency. There was a strong correlation between the formaldehyde and total volatile organic compounds (TVOCs) with both types of floorings using the two different methods. The formaldehyde emission rate and TVOC results were higher when tested using the FLEC method than with the 20L small chamber method. The emission rate was affected by the joint edge length in laminate flooring. Toluene, ethylbenzene and xylene were the main VOCs emitted from laminate flooring, and there were more unidentified VOCs emitted than identified VOCs. The samples heated with a floor heating system emitted more formaldehyde than those heated using an air circulation system due to the temperature difference between the bottom panel and flooring. The TVOC emission level of the samples was higher when an air circulation system was used than when a floor heating system was used due to the high ventilation rate.
Kim, Ki-Wook; Lee, Byoung-Ho; Kim, Sumin; Kim, Hyun-Joong; Yun, Ju-Ho; Yoo, Seung-Eul; Sohn, Jong Ryeul
In: Journal of Hazardous Materials, 187 (1), pp. 37 - 43, 2011, ISSN: 0304-3894.
Various experiments, such as the thermal extract (TE) method, field and emission cell (FLEC) method and 20L small chamber, were performed to examine the total volatile organic compound (TVOC) emissions from bio-composites. The TVOC of neat poly(lactic acid) (PLA) was ranged from 0.26mg/m2h to 4.11mg/m2h with increasing temperature. For both PLA bio-composites with pineapple flour and destarched cassava flour, the temperature increased from 0.30mg/m2h to 3.72mg/m2h and from 0.19mg/m2h to 8.74mg/m2h, respectively. The TVOC emission factors of all samples increased gradually with increasing temperature. Above 70°C, both PLA-P and PLA-C composites had higher TVOC emission factors than neat PLA due to the rapid emission of natural volatile organic compounds (VOCs), such as furfural (2-furancarboxyaldehyde). PLA composites containing 30wt% flour had high 1,4-dioxane reduction ability, >50%. The TVOC of poly(butylene succinate) (PBS) was emitted rapidly from 50°C to 90°C due to succinic acid from the pyrolysis of PBS. The TVOC emission factors of PLA bio-composite and PBS bio-composites were reduced using the bake-out method (temperature at 70°C and baking time 5h). The initial TVOC emission factors of the PLA and PBS bio-composites with pineapple flour and destarched cassava flour were reduced by the baking treatment using FLEC. The TVOC factors from PLA and PBS decreased until 5 days and were commonly maintained a relatively constant value after 5 days using 20L small chamber. The decrease in TVOC emission showed a similar trend to that of the TE and FLEC method. This method confirmed the beneficial effect of the baking treatment effect for polypropylene and linear density polyethylene (LDPE).
Ham, Jason E; Wells, Raymond J
In: Chemosphere, 83 (3), pp. 327 - 333, 2011, ISSN: 0045-6535.
Indoor environments are dynamic reactors where consumer products (such as cleaning agents, deodorants, and air fresheners) emit volatile organic compounds (VOCs) that can subsequently interact with indoor oxidants such as ozone (O3), hydroxyl radicals, and nitrate radicals. Typically, consumer products consist of mixtures of VOCs and semi-VOCs which can react in the gas-phase or on surfaces with these oxidants to generate a variety of oxygenated products. In this study, the reaction of a pine-oil cleaner (POC) with O3 (100ppb) on a urethane-coated vinyl flooring tile was investigated at 5% and 50% relative humidity. These results were compared to previous α-terpineol+O3 reactions on glass and vinyl surfaces. Additionally, other terpene and terpene alcohol mixtures were formulated to understand the emission profiles as seen in the POC data. Results showed that the α-terpineol+O3 reaction products were the prominent species that were also observed in the POC/O3 surface experiments. Furthermore, α-terpineol+O3 reactions generate the largest fraction of oxygenated products even in equal mixtures of other terpene alcohols. This finding suggests that the judicial choice of terpene alcohols for inclusion in product formulations may be useful in reducing oxidation product emissions.
Nriagu, J O (Ed.)
Subject Index Incollection
In: Nriagu, J O (Ed.): Encyclopedia of Environmental Health, pp. 809 - 1079, Elsevier, Burlington, 2011, ISBN: 978-0-444-52272-6.
In: International Journal of Heat and Mass Transfer, 53 (23), pp. 5478 - 5486, 2010, ISSN: 0017-9310.
Membrane-based total heat exchangers (or energy recovery ventilators) are the key equipments to fresh air ventilation, which is helpful for the control of respiratory diseases like Swine flu and SARs. Cross flow has been the predominant flow arrangement for these equipments. However performances are limited with this arrangement. A counter flow arrangement is the best. In this research, a quasi-counter flow parallel-plates total heat exchanger is constructed and investigated. A detailed mathematical modeling is conducted and the model is experimentally verified. The temperature and humidity values on membrane surfaces, and in the fluids are solved as a conjugate problem. The fluid flow, heat and mass transport equations in the entry regions are solved directly. The mean Nusselt and Sherwood numbers, and the sensible and latent effectiveness of the exchanger are calculated. It is found that the effectiveness of the current arrangement lie between those for cross flow and those for counter flow arrangements. The results also found that the flow can be divided distinctly into three zones: two cross-like zones and a pure-counter flow zone. The less the cross-like zones are, the larger the pure-counter flow zone is, and the greater the effectiveness is. The study also provides a solution of modeling mass transfer with FLUENT software from heat mass analogy.
Kim, Ki-Wook; Kim, Sumin; Kim, Hyun-Joong; Park, Jin Chul
In: Journal of Hazardous Materials, 177 (1), pp. 90 - 94, 2010, ISSN: 0304-3894.
Formaldehyde and TVOC are emitted from wood-based panels that are made using wood particles, wood fiber, wood chips and formaldehyde-based resins. This study examined the formaldehyde and TVOC emission behavior of medium density fiberboard (MDF) overlaid with three types of uncoated lignocellulosic surface materials (oak decorative veneer, low pressure melamine impregnated paper and high pressure melamine impregnated paper) and four types of coated surface materials (coated paper, two types of finishing foils, and PVC) using the Field and Laboratory Emission Cell (FLEC) method and a 20L small chamber method. The uncoated lignocellulosic surface materials exhibited lower formaldehyde and TVOC emission levels. The coated surface materials did not show reduced TVOC emissions but the formaldehyde emission was reduced in the 20L small chamber test. In the FLEC test, both the uncoated lignocellulosic surface materials and coated surface materials showed lower TVOC and formaldehyde emissions from MDF.
Missia, Dafni A; Demetriou, E; Michael, N; Tolis, E I; Bartzis, J G
Indoor exposure from building materials: A field study Journal Article
In: Atmospheric Environment, 44 (35), pp. 4388 - 4395, 2010, ISSN: 1352-2310.
The present study has been conducted in the frame of BUMA (Prioritization of Building Materials Emissions as indoor pollution sources), a European funded project, aiming at assessing the exposure to emitted compounds in indoor air. Field campaigns in five (5) European cities (Milan, Copenhagen, Dublin, Athens and Nicosia) were carried out. These campaigns covered weekly winter and summer concentration measurements in two (2) public buildings and two (2) private houses in each city. BTEX, terpenes, and carbonyls were measured using passive sampling in two sites inside the building and one outside. VOC emission measurements on selected building material have also been performed using Field and Laboratory Emission Cell (FLEC). The results on indoor concentrations for compounds such as formaldehyde (1.2–62.6μgm−3), acetaldehyde (0.7–41.6μgm−3), toluene (0.9–163.5μgm−3), xylenes (0.2–177.5μgm−3) and acetone (2.8–308.8μgm−3) have shown diversity and relatively significant indoor sources depending on the building type, age etc. Indoor concentrations of these substances are varied depending on the building age and type. The percentage of approximately 40% of the indoor air quality levels originated from building materials.
In: Journal of Hazardous Materials, 176 (1), pp. 14 - 19, 2010, ISSN: 0304-3894.
This paper assesses the reproducibility of testing formaldehyde and TVOC emission behavior from wood flooring composites bonded by urea–formaldehyde resin at various manufacturing steps for surface finishing materials. The surface adhesion step of laminate flooring for this research was divided into two steps; HDF only and HDF with LPMs. In the case of engineered flooring, the manufacturing steps were divided into three steps; plywood only, fancy veneer bonded on plywood and UV coated on fancy veneer with plywood. Formaldehyde and VOCs emission decreased at the process of final surface finishing materials; LPMs were applied on the surface of HDF for laminate flooring. Although emissions increased when fancy veneer was bonded onto plywood in the case of engineered flooring, emission was dramatically reduced up to similar level with plywood only when final surface finishing; UV-curable coating was applied on fancy veneer. This study suggests that formaldehyde and VOCs emission from floorings can be controlled at manufacturing steps for surface finishing.
Clausen, Per Axel; Liu, Zhe; Xu, Ying; Kofoed-Sørensen, Vivi; Little, John C
In: Atmospheric Environment, 44 (23), pp. 2760 - 2766, 2010, ISSN: 1352-2310.
The emission of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring with ∼15% (w/w) DEHP as plasticizer was measured at 22 °C in five FLECs + one blank FLEC (Field and Laboratory Emission Cell). Initially, the flow through all FLECs was 450 ml min−1. After 689 days the flows were changed to 1000 ml min−1, 1600 ml min−1, 2300 ml min−1, and 3000 ml min−1, respectively, in four FLECs, and kept at 450 ml min−1 in one FLEC. Air samples were collected from the effluent air at regular intervals. After 1190 days the experiments were terminated and the interior surfaces of all six FLECs were rinsed with methanol to estimate the internal surface concentrations of DEHP. The DEHP air concentration and specific emission rate (SER) at steady state was estimated for the five different flow rates. The steady-state concentrations decreased slightly with increasing air flow with only the two highest flow rates resulting in significantly lower concentrations. In contrast, the SERs increased significantly. Despite large variation, the internal surface concentrations appeared to decrease slightly with increasing FLEC flow. Computational fluid dynamic (CFD) simulations suggest that the interior gas and surface concentrations were roughly uniform for the low flow case (450 ml min−1), under which, the partitioning between the FLEC internal surface and chamber air was examined. Although paired t-tests showed no difference between CFD and experimental results for DEHP air concentrations and SERs at steady-state conditions, CFD indicated that the experimental DEHP surface concentrations in the FLECs were underestimated. In conclusion, the experiments showed that the emission of DEHP from vinyl flooring is subject to “external” control and that the SER is strongly and positively dependent on the air exchange rate. However, the increased SER almost compensates for the decrease in gas-phase concentration caused by the increased air exchange.
An, Jae-Yoon; Kim, Sumin; Kim, Hyun-Joong; Seo, Janghoo
In: Building and Environment, 45 (8), pp. 1826 - 1833, 2010, ISSN: 0360-1323.
Formaldehyde and volatile organic compounds (VOCs) from the adhesive, flooring, and flooring with adhesive were measured using a desiccator, a 20-L chamber and a field and laboratory emission cell (FLEC). Flooring with an adhesive is similar to that used in construction was applied to a floor heating system and an air circulation system, and the surface temperature of the flooring was set to 20 °C, 26 °C and 32 °C. The rate of formaldehyde emission from the flooring was the highest at 32 °C using a desiccator and decreased with time. The formaldehyde and aldehyde emissions from the samples using a 20-L chamber and FLEC showed a similar tendency. The VOCs emission trends with the 20-L chamber and FLEC were similar. The rate of formaldehyde and TVOC emission determined using FLEC was higher than that determined using the 20-L chamber method. The flooring emitted primarily benzene, toluene, ethylbenzene, styrene, xylene, as well as some unknown VOCs. There was a strong correlation between formaldehyde and TVOC emission for the 20-L chamber and FLEC. Samples using a floor heating system showed higher formaldehyde emission than those using an air circulation system. The level of TVOC emission was higher from the samples using an air circulation system than those using the floor heating system.
Kim, Sumin; Choi, Yoon-Ki; Park, Kyung-Won; Kim, Jeong Tai
In: Bioresource Technology, 101 (16), pp. 6562 - 6568, 2010, ISSN: 0960-8524.
This paper reviews different methods for the analysis of formaldehyde and volatile organic compounds (VOCs) from wood-based panel materials for furniture and building interiors and highlights research on reduction of emission from wood-based panels that can adversely affect indoor air quality. In Korea, standard test methods have been developed to determine formaldehyde and VOC emissions from building products, and the Ministry of Environment regulates the use of building materials with pollutant emissions. Desiccator and perforator methods are being used for formaldehyde and the chamber and field and laboratory emission cell (FLEC) methods for VOC and formaldehyde emissions. The VOC analyzer is a suitable pre-test method for application as a total VOC (TVOC) emission test and bake-out is a useful method to reduce TVOC and formaldehyde emissions from furniture materials in indoor environments.
Ekelund, M; Azhdar, B; Gedde, U W
In: Polymer Degradation and Stability, 95 (9), pp. 1789 - 1793, 2010, ISSN: 0141-3910.
The migration of di(2-ethylhexyl)phthalate (DEHP) from poly(vinyl chloride) (PVC) to a surrounding gas phase at temperatures below 120 °C kinetically is controlled by evaporation. The effects on the DEHP loss rate of nitrogen flow rate, relative humidity and degradation of the plasticizer at 100 °C was assessed. The sample mass decreased linearly with time for both pristine DEHP and plasticized PVC at comparable rates, suggesting that a thin film of DEHP was present on the jacketing insulation during desorption. The latter hypothesis was supported by infrared spectroscopy and by the fact that DEHP is an amphiphilic molecule that will tend to aggregate at the surface with the hydrophobic 2-ethylhexyl units at the air interface. The effect on the migration rate of moisture present in the gas phase was negligible. The DEHP loss rate increased in a retarding non-linear fashion with increasing gas flow rate. In one of the experiments, DEHP was accidently degraded as revealed by discoloration, the presence of low molar mass degradation products (liquid chromatography) containing additional carbonyl groups (infrared spectroscopy) and an increase in the evaporation rate at temperatures between 100 and 130 °C.
Yamashita, Shohei; Kume, Kazunari; Horiike, Toshiyuki; Honma, Nobuyuki; Fusaya, Masahiro; Ohura, Takeshi; Amagai, Takashi
In: Journal of Hazardous Materials, 178 (1), pp. 370 - 376, 2010, ISSN: 0304-3894.
Volatile organic compounds (VOCs) emitted from building and furnishing materials are frequently observed in high concentrations in indoor air. Nondestructive analytical methods that determine the main parameters influencing concentration of the chemical substances are necessary to screen for sources of VOC emissions. Toward this goal, we have developed a new flux sampler, referred to herein as an emission cell for simultaneous multi-sampling (ECSMS), that is used for screening indoor emission sources of VOCs and for determining the emission rates of these sources. Because the ECSMS is based on passive sampling, it can be easily used on-site at a low cost. Among VOCs, low-molecular-weight carbonyl compounds including formaldehyde are frequently detected at high concentrations in indoor environments. In this study, we determined the reliability of the ECSMS for the collection of formaldehyde and other carbonyl compounds emitted from wood-based composites of medium density fiberboards and particleboards. We then used emission rates determined by the ECSMS to predict airborne concentrations of formaldehyde emitted from a bookshelf in a large chamber, and these data were compared to formaldehyde concentrations that were acquired simultaneously by means of an active sampling method. The values obtained from the two methods were quite similar, suggesting that ECSMS measurement is an effective method for screening primary sources influencing indoor concentrations of formaldehyde.
Min, Jingchun; Hu, Teng; Liu, Xiaowei
Evaluation of moisture diffusivities in various membranes Journal Article
In: Journal of Membrane Science, 357 (1), pp. 185 - 191, 2010, ISSN: 0376-7388.
An experimental set-up was designed and constructed to investigate the moisture permeation through a membrane. The test section consists mainly of an airflow channel, a membrane, and a water tank, with the membrane being sandwiched between the channel and water tank. An air gap exists between the membrane and the water in the water tank to avoid any possible wetting of the membrane by the water. Moisture transfers from the water to the airstream in the channel through the air gap and membrane. The moisture transfer process was described using a serial resistance model, which involves the convective moisture resistance in the channel, the moisture resistance through membrane, and the moisture resistance caused by the air gap. Special methods were developed to determine the convective and air gap resistances, with the membrane resistance obtained by subtracting such two resistances from the total resistance. Tests were conducted on three membranes including the PVDF (poly vinylidene fluoride), PES (poly ether sulfone) and cellulose membranes for airflow rates from 3.0 to 5.0l/min, yielding Reynolds numbers from 117 to 195. The results showed that the moisture diffusivities in these membranes were in the order of 10−7 to 10−6kg/ms, with the PVDF yielding the maximum diffusivity and the PES giving the minimum diffusivity.
Kagi, N; Fujii, S; Tamura, H; Namiki, N
In: Building and Environment, 44 (6), pp. 1199 - 1205, 2009, ISSN: 0360-1323.
Chemical reactions on the surface of building materials can lead to secondary emissions from these materials that influence indoor air quality. Many studies have been made on the physical processes that influence material emissions. However, there are only a few studies on secondary emissions resulting from exposure of building material surfaces to ozone or ultraviolet (UV) irradiation. Therefore, this study was aimed at elaborating on the emission of chemicals resulting from chemical reactions initiated by the exposure of the surface of flooring materials to ozone or UV irradiation. The laboratory tests were conducted to estimate gas-phase emissions from the flooring materials when they were exposed to ozone or various kinds of light irradiation (infrared, sunlight, UV-A and UV-B lamps). The infrared and sunlight lamps significantly increased the temperature of the test specimens and, in turn, increased the emission rate for various organic compounds. The flooring materials used in this study had been treated with UV-cured surface coatings during their manufacturing. As a result, when exposed to UV irradiation, chemical transformations occurred resulting in the emission of a number of secondary products, including formaldehyde, acetaldehyde, cyclohexanone and benzaldehyde. Ozone reacted with chemicals present in the flooring materials to increase the emission rates of formaldehyde and acetaldehyde. Hence, the exposure of ozone and UV irradiation increased the secondary emissions of formaldehyde, even though the low formaldehyde emission type of flooring material was employed.
Ham, Jason E; Wells, Raymond J
In: Atmospheric Environment, 43 (26), pp. 4023 - 4032, 2009, ISSN: 1352-2310.
The surface-phase reaction products of dihydromyrcenol (2,6-dimethyl-7-octen-2-ol) with ozone (O3), air, or nitrogen (N2) on silanized glass, glass and vinyl flooring tile were investigated using the recently published FACS (FLEC (Field and Laboratory Emission Cell) Automation and Control System). The FACS was used to deliver ozone (100 ppb), air, or N2 to the surface at a specified flow rate (300 mL min−1) and relative humidity (50%) after application of a 2.0% dihydromyrcenol solution in methanol. Oxidation products were detected using the derivatization agents: O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) and N,O-bis(trimethysilyl)trifluoroacetamide (BSTFA). The positively identified reaction products were glycolaldehyde, 2,6-dimethyl-5-heptenal, and glyoxal. The proposed oxidation products based on previously published VOC/O3 reaction mechanisms were: 2,6-dimethyl-4-heptenal, 6-methyl-7-octen-2-one and the surface-specific reaction products: 6-methyl-6-hepten-2-one, 6-methyl-5-hepten-2-one, and 6-hydroxy-6-methylheptan-2-one. Though similar products were observed in gas-phase dihydromyrcenol/O3 reactions, the ratio, based on peak area, of the reaction products was different suggesting stabilization of larger molecular weight species by the surface. Emission profiles of these oxidation products over 72 h are also reported.
Shinohara, Naohide; Kai, Yuya; Mizukoshi, Atsushi; Fujii, Minoru; Kumagai, Kazukiyo; Okuizumi, Yumiko; Jona, Miki; Yanagisawa, Yukio
In: Building and Environment, 44 (5), pp. 859 - 863, 2009, ISSN: 0360-1323.
In indoor environments with high levels of air pollution, it is desirable to remove major sources of emissions to improve air quality. In order to identify the emission sources that contribute most to the concentrations of indoor air pollutants, we used passive flux samplers (PFSs) to measure emission rates of carbonyl compounds and volatile organic compounds (VOCs) from many of the building materials and furnishings present in a room in a reinforced concrete building in Tokyo, Japan. The emission flux of formaldehyde from a desk was high (125μg/m2/h), whereas fluxes from a door and flooring were low (21.5 and 16.5μg/m2/h, respectively). The emission fluxes of toluene from the ceiling and the carpet were high (80.0 and 72.3μg/m2/h, respectively), whereas that from the flooring was low (9.09μg/m2/h). The indoor and outdoor concentrations of formaldehyde were 61.5 and 8.64μg/m3, respectively, and those of toluene were 43.2 and 17.5μg/m3, respectively. The air exchange rate of the room as measured by the perfluorocarbon tracer (PFT) method was 1.84/h. Taking into consideration the area of the emission sources, the carpet, ceiling, and walls were identified as the principal emission sources, contributing 24%, 20%, and 22% of the formaldehyde, respectively, and 22%, 27%, and 14% of the toluene, respectively, assuming that the emission rate from every major emission sources could be measured. In contrast, the door, the flooring, and the desk contributed little to the indoor levels of formaldehyde (1.0%, 0.54%, and 4.1%, respectively) and toluene (2.2%, 0.31%, and 0.85%, respectively).
In: Bioresource Technology, 100 (2), pp. 744 - 748, 2009, ISSN: 0960-8524.
The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring using the natural tannin form bark in the wood. The natural wattle tannin adhesive were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. PVAc was added to the natural tannin adhesive to increase viscosity of tannin adhesive for surface bonding. For tannin/PVAc hybrid adhesives, 5%, 10%, 20% and 30% of PVAc to the natural tannin adhesives were added. tannin/PVAc hybrid adhesives showed better bonding than the commercial natural tannin adhesive with a higher level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method), field and laboratory emission cell (FLEC) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial the natural tannin adhesive and tannin/PVAc hybrid adhesives. By desiccator method and FLEC, the formaldehyde emission level of each adhesive showed the similar tendency. All adhesives satisfied the E1 grade (below 1.5mg/L) and E0 grade (below 0.5mg/L) with UV coating. VOC emission results by FLEC and VOC analyzer were different with the formaldehyde emission results. TVOC emission was slightly increased as adding PVAc.
Giorgi, Rodorico; Chelazzi, David; Fratini, Emiliano; Langer, Sarka; Niklasson, Annika; Rådemar, Maria; Svensson, Jan-Erik; Baglioni, Piero
In: Journal of Cultural Heritage, 10 (2), pp. 206 - 213, 2009, ISSN: 1296-2074.
Acetic and formic acid vapors emitted from woodwork in historical organs are very important corrosive agents for lead pipes. These acids are slowly released from the wood both during playing and when the pipes are silent. To inhibit this emission process, the wood surface can be modified, by creating a protective layer with alkaline features. However, a coating of wood is not recommended since this could modify the appearance and create a layer not perfectly compatible with the substrate. For this reason, we propose to use some innovative nanotechnology that has been successfully applied for the deacidification of wood samples coming from the Vasa shipwreck. Application of calcium (or magnesium) hydroxide nanoparticles, with sizes ranging from 30–150nm, allowed a homogeneous distribution of particles through the surface layer of wood simply by soaking (or spraying) it in a alcoholic (or mixed with less polar solvents) dispersion of nanoparticles. Nanoparticles do not modify the wood appearance and distribute randomly within the first layers of wood. The small size of particles accounts for the high reactivity with CO2 from the air, to give the alkaline reserve of carbonates that provide high efficacy in the neutralization of gaseous acids. The emission of volatile organic compounds (VOC) from the treated wood was determined by using an emission test cell, Field and Laboratory Emission Cell (FLEC). The results show that the emissions of acetic acid vapor from nanoparticles treated wood was very low (<70μg/m2h) during the first 13 month. In contrast, untreated wood emitted high concentrations of acetic acid vapor (200–400μg/m2h).
Nicolle, Jérôme; Desauziers, Valérie; Mocho, Pierre; Ramalho, Olivier
In: Talanta, 80 (2), pp. 730 - 737, 2009, ISSN: 0039-9140.
The FLEC®-SPME sampler, described in a previous paper, consists of an emission cell coupled with solid phase microextraction (SPME) for passive sampling of VOCs emitted from building materials. It represents an interesting alternative to standard dynamic sampling protocol as it is easier to implement. If standard dynamic sampling determines emission rates, passive FLEC®-SPME aims to the determination of the concentration in air at the material surface. That could be assumed provided that material/air equilibrium is reached. Thus, VOCs emission kinetics were studied for 3 different materials (pine wood panel, carpet and PVC floor) to determine equilibrium times. Then, the relevance of the method has been assessed using new materials through a 3-day emission test. Qualitative results were compared to those obtained from the standard method to check the ability of FLEC®-SPME to detect the most toxic compounds, named “VOCs of interest” and listed in the French regulation. Minor differences were observed, so this methodology seems promising, especially for field studies aiming in the identification of VOCs sources in buildings. Moreover, the concentration at the material surface combined to emission modeling could be used to predict indoor VOCs concentrations helping in indoor air quality diagnostic.
Westberg, Åsa; Momcilovic, Dane; Björk, Folke; Karlsson, Sigbritt
In: Polymer Degradation and Stability, 94 (6), pp. 914 - 920, 2009, ISSN: 0141-3910.
2-Ethyl hexanol from hydrolysed di-octyl-phthalate (DOP) may cause a secondary emission from building products such as PVC carpets and/or glues causing indoor air pollution. In the present study, a micro-scale headspace vial (MHV) method, earlier developed by us, was refined to study the degradation of DOP and di-isononyl phthalate (DINP) in humid and alkaline environments. By HS-SPME it was possible to extract the degradation products at low temperature, 35°C, which limits the risks of unwanted degradation during sampling. Three different types of HS-SPME fibres were evaluated. The carbowax-divinyl benzene (CW/DVB) fibre had the highest extraction capacity of 2-ethyl-1-hexanol and 5-nonanol. Although significantly shorter extraction times could be used with the 7μm and 30μm poly-dimethylsiloxane (PDMS) fibres, the CW/DVB fibre was found to be the most suitable for these alcohols. Furthermore, it was found that pH of the alkaline environment strongly influences the formation of degradation products from DOP and DINP.
Järnström, H; Saarela, K; Kalliokoski, P; Pasanen, A -L
In: Environment International, 34 (3), pp. 420 - 427, 2008, ISSN: 0160-4120, (Proceedings of the 1st Conference of the UK Network on Persistent Organic Pollutants (POPs) 29th and 30th March 2006, University of Birmingham, UK).
Emission rates of volatile organic compounds (VOCs) and ammonia measured from six PVC materials and four adhesives in the laboratory were compared to the emission rates measured on site from complete structures. Significantly higher specific emission rates (SERs) were generally measured from the complete structures than from individual materials. There were large differences between different PVC materials in their permeability for VOCs originating from the underlying structure. Glycol ethers and esters from adhesives used in the installation contributed to the emissions from the PVC covered structure. Emissions of 2-ethylhexanol and TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) were common. High ammonia SERs were measured from single adhesives but their contribution to the emissions from the complete structure did not appear as obvious as for VOCs. The results indicate that three factors affected the VOC emissions from the PVC flooring on a structure: 1) the permeability of the PVC product for VOCs, 2) the VOC emission from the adhesive used, and 3) the VOC emission from the backside of the PVC product.
Clausen, Per Axel; Xu, Ying; Kofoed-Sørensen, Vivi; Little, John C; Wolkoff, Peder
In: Atmospheric Environment, 41 (15), pp. 3217 - 3224, 2007, ISSN: 1352-2310, (Indoor Air 2005 - 10th International Conference on Indoor Air Quality and Climate (Part I)).
Asthma in children appears to be associated with both phthalate esters and dampness in buildings. An important question is whether the concentrations of phthalate esters correlate with dampness (expressed as relative humidity—RH) in indoor air. The objective was to study the influence of RH on the specific emission rate (SER) of di-(2-ethylhexyl)phthalate (DEHP) from one type of vinyl flooring in the well characterized Field and Laboratory Emission Cell (FLEC). The vinyl flooring with ca. 17% (w/w) DEHP as plasticizer was tested in 6 FLECs at 22°C. The RH in the 6 FLECs was 10%, 30%, 50% (in triplicate) and 70%. The RH was changed after 248d in 2 of the 50%-FLECs to 10% and 70%, and to 50% in the 10%-and 70%-FLECs. The data show that the SER of DEHP from vinyl flooring in FLECs during a 1yr period is independent of the RH. A new physically based emission model for semivolatile organic compounds was found to be consistent with the experimental data and independent of the RH. The model helps to explain the RH results, because it appears that RH does not significantly influence any of the identified controlling mechanisms.
Qian, Ke; Zhang, Yinping; Little, John C; Wang, Xinke
In: Atmospheric Environment, 41 (2), pp. 352 - 359, 2007, ISSN: 1352-2310.
Based on the most recently published mass transfer model of volatile organic compound (VOC) emissions from dry building materials, it is found that the dimensionless emission rate and total emission quantity are functions of just four dimensionless parameters, the ratio of mass transfer Biot number to partition coefficient (Bim/K), the mass transfer Fourier number (Fom), the dimensionless air exchange rate (Nδ2/Dm) and the ratio of building material volume to chamber or room volume (Aδ/V). Through numerical analysis and data fitting, a group of dimensionless correlations for estimating the emission rate from dry building materials is obtained. The predictions of the correlations are validated against the predictions made by the mass transfer model. Using the correlations, the VOC emission rate from dry building materials can be conveniently calculated without having to solve the complicated mass transfer equations. Thus it is very simple to estimate VOC emissions for a given condition. The predictions of the correlations agree well with experimental data in the literature except in the initial few hours. Furthermore, based on the correlations, a relationship between the emission rates of a material in two different situations is deduced. With this relationship, the results for a given building material in a test chamber can be scaled to those under real conditions, if the dimensionless parameters are within the appropriate region for the correlations. The relationship also explicitly explains the impacts of air velocity, load ratio, and air exchange rate on the VOC emission rate, which determines the feasibility of assuming that the VOC emission rates in real conditions are the same as those in the test chambers.
Uchiyama, Shigehisa; Matsushima, Erica; Kitao, Nahoko; Tokunaga, Hiroshi; Ando, Masanori; Otsubo, Yasufumi
In: Atmospheric Environment, 41 (38), pp. 8825 - 8830, 2007, ISSN: 1352-2310.
The effects of natural compounds on reducing formaldehyde emission from plywood were investigated. Urea, catechin and vanillin were examined as the natural formaldehyde reducers. The microemission cell, with an internal volume of 35ml, the maximum exposed test surface area of 177cm2 and an air purge flow rate of 50mlmin−1, was used to measure specific emission rate (SER). In the case of no reducer treatment, formaldehyde emission from plywood was fast and SERs were 4.4mgm−2h−1 at 30°C and 15mgm−2h−1 at 60°C. When this plywood was treated with the natural compounds, the SERs of formaldehyde were decreased at all temperatures. In the case of urea treatment, the SERs of formaldehyde decreased to 0.30mgm−2h−1 at 30°C and 0.65mgm−2h−1 at 60°C. When the urea treatment was applied to the inside of kitchen cabinet (made from plywood; 270cm wide, 60cm deep, 250cm high), the concentration of formaldehyde was reduced substantially from 1600 to 130μgm−3. The reducing effect of formaldehyde continued during the observation period (6 months), with a mean concentration of 100μgm−3. Reducers in the plywood would react with released formaldehyde. Application of natural compounds such as urea, catechin and vanillin could provide a simple and effective approach for suppressing formaldehyde emission from plywood.
Abstracts Journal Article
In: Fuel and Energy Abstracts, 48 (3), pp. 146 - 223, 2007, ISSN: 0140-6701.
Järnström, H; Saarela, K; Kalliokoski, P; Pasanen, A -L
In: Atmospheric Environment, 41 (11), pp. 2290 - 2302, 2007, ISSN: 1352-2310.
A 3-year research project was established in 1999 to create numerical reference data for material emissions during the time of construction and during the first year. Seven buildings, representing the present construction practice in Finland, were investigated. Material emissions were measured by using the field and laboratory cell (FLEC) during the time of construction, in the newly finished, and in the 6- and 12-month-old buildings. The emission rates for volatile organic compounds (VOCs), formaldehyde, and ammonia were determined. The highest total VOCs (TVOC) emissions were measured in the newly finished buildings from the ceiling structure and from some of the PVC floor coverings. These emissions were up to 1300–2000μgm−2h−1. Individual VOCs with emission rates above 50μgm−2h−1 included 2-(2-butoxyethoxy) ethanol and its acetate, C4–C16-substituted alkylbenzenes, and xylenes. The mean TVOC emission decreased at least to the Finnish M1-class level (200μgm−2h−1) from all surfaces and in all the buildings in 6–12 months. The ammonia and formaldehyde emissions from the ceiling structure were 20–60μgm−2h−1 in the newly finished buildings and the M1-levels (30/50μgm−2h−1) were exceeded in some cases. These emissions even increased in some buildings during the follow-up period indicating the difference between emissions measured in the laboratory and on site from real structures. Reference values based on the means and 95th percentile are presented to be utilised in both quality control and while investigating indoor air quality problems which are suspected to be caused by a defect structure.
Shinohara, Naohide; Fujii, Minoru; Yamasaki, Akihiro; Yanagisawa, Yukio
In: Atmospheric Environment, 41 (19), pp. 4018 - 4028, 2007, ISSN: 1352-2310.
A new passive flux sampler (PFS) was developed to measure emission rates of formaldehyde and to determine emission sources in indoor environments. The sampler consisted of a glass Petri dish containing a 2,4-dinitrophenyl hydrazine (DNPH)-impregnated sheet. At the start of sampling, the PFS was placed with the open face of the dish on each of the indoor materials under investigation, such as flooring, walls, doors, closets, desks, beds, etc. Formaldehyde emitted from a source material diffused through the inside of the PFS and was adsorbed onto the DNPH sheet. The formaldehyde emission rates could be determined from the quantities adsorbed. The lower determination limits were 9.2 and 2.3μgm−2h−1 for 2- and 8-h sampling periods. The recovery rate and the precision of the PFS were 82.9% and 8.26%, respectively. The emission rates measured by PFS were in good agreement with the emission rates measured by the chamber method (R2=0.963). This shows that it is possible to take measurements of the formaldehyde emission rates from sources in a room and to compare them. In addition, the sampler can be used to elucidate the emission characteristics of a source by carrying out emission measurements with different air-layer thicknesses inside the PFS and at different temperatures. The dependency of the emission rate on the thickness of the air layer inside the PFS indicated whether the internal mass transfer inside the source material or the diffusion in the gas-phase boundary layer controlled the formaldehyde emission rate from a material. In addition, as a pilot study, the formaldehyde emission rates were measured, and the largest emission source of formaldehyde could be identified from among several suspected materials in a model house by using the PFS.
Abstracts for issue 48/2 Journal Article
In: Fuel and Energy Abstracts, 48 (2), pp. 74 - 136, 2007, ISSN: 0140-6701.
In: International Journal of Heat and Mass Transfer, 49 (5), pp. 1176 - 1184, 2006, ISSN: 0017-9310.
This research focuses studies of water permeation potential through a polymer membrane with the help of a standard field and laboratory emission cell. Special efforts are devoted to finding a correlation governing the relations between the number of transfer units (NTU) and the moisture exchange effectiveness. As a first step, moisture diffusivity in the hydrophilic polymer membrane is experimentally measured. In combination with mathematical modeling, the moisture concentration distributions in the cell, the water uptake gradients in the membrane, as well as the local vapor emission rate on membrane surface, are investigated. The results are that the emission rates show a non-uniform character and a polynomial equation governing the moisture exchange effectiveness and the dimensionless number of transfer units, could be used to inversely estimate the diffusivity of water vapor in hydrophilic membranes. The form and the value of constants in the equation are obtained.
Luo, R; Niu, J L
In: Building and Environment, 41 (9), pp. 1148 - 1160, 2006, ISSN: 0360-1323.
The diffusion and partition coefficients of eight volatile organic compounds (VOCs) in cement slabs were experimentally determined using a field and laboratory emission cell (FLEC) system based on the method developed in a previous study on the water vapor diffusion. A cement slab planted with a mixture of eight VOCs was placed in an one-FLEC system to undergo the mass diffusion in the slab and the emission to air flowing through the FLEC. The concentration of each VOC in the air flowing out of the FLEC was measured according to the EPA Method TO-17 using sorbent tube-automatic thermal desorption (ATD) and the gas chromatography-mass spectrum detector (GC-MSD) system. The diffusion and partition coefficients were then obtained by solving the inverse problem of the one-dimensional unsteady mass diffusion equations in the cement slab. And, the partition coefficient was also obtained from the total mass transfer estimated from the VOC concentration measurements and air flowrate, which was equivalent to the headspace concentration-weighting method.
In: Journal of Membrane Science, 269 (1), pp. 75 - 83, 2006, ISSN: 0376-7388.
Moisture diffusivity in hydrophilic membranes is measured traditionally by stepwise drying experiments or steady state permeation tests. Problems with these methods are that the convective moisture resistance in membrane boundary layers is seldom taken into account, and the distributed nature of moisture emissions on membrane surface and air concentration above it often give distorted results. In this study, a new method designed to overcome these imperfections is proposed in predicting the diffusivity of moisture in hydrophilic membranes. The key equipment is a filed and laboratory emission cell. The whole technique comprises two steps: in the first step, the cell surface convective mass transfer coefficient is obtained; and in the second step, moisture diffusivity in membrane is measured. The technique also involves a two-dimensional modeling of moisture transport in membranes.
Volume Index, layout sheets att’ed Journal Article
In: International Journal of Heat and Mass Transfer, 49 (25), pp. I - XXXIV, 2006, ISSN: 0017-9310.
Chen, Xiao Dong
In: Separation and Purification Technology, 48 (2), pp. 121 - 132, 2006, ISSN: 1383-5866, (Separation and Purification in the Food Industry).
Drying is a complex process to model. Certain assumptions, such as an isothermal process, a uniform temperature process and a heat transfer limiting process, where no mass transfer resistance is considered and so on. Lewis number (Le) is defined as the ratio of the thermal diffusivity to the mass diffusivity. It indicates if the heat and mass transfer processes are whether mass transfer limiting (Le≫1), heat transfer limiting (Le≪1), or are much coupled processes (Le∼1). The Lewis number for drying is calculated using the properties that may not be realistic, e.g. that by neglecting the effect of the water sorption capability of the material being dried. Sometimes, quite different conclusions on whether or not drying is limited by heat transfer can result. Here, two new approaches to Lewis number estimation are presented for hygroscopic materials. Sample calculations are made for milk particle drying as an illustration of the principles outlined.
Li, Feng; Niu, Jianlei; Zhang, Lizhi
In: Building and Environment, 41 (10), pp. 1317 - 1325, 2006, ISSN: 0360-1323.
Paints are widely used in residential and commercial buildings. The surface areas covered by this kind of coatings are usually very large. The volatile organic compounds (VOCs) emissions from such kind of materials will affect indoor air quality decisively. A relatively simple but physically-based model was developed to simulate VOCs emissions from paints. The model parameters have distinct physical meanings and thus the model is easy to scale up. The field and laboratory emission cell (FLEC) was used to investigate the VOCs emissions from commercially available water-based emulsion paint. Totally 23 individual VOCs were detected and quantified, the most abundant VOC was 1-ethyl-3-methylbenzene. Test data were used to obtain model parameters and to validate the proposed model. Good agreements between experimental data and model predictions were evidenced. Paints applied on two different substrates aluminium and particle board were simulated. Results indicated that real substrates like particle board would act like a ‘sponge’, which lowers the peak concentration but prolongs the presence of VOCs from the applied paint.
04/00472 Business excellence through resource efficiency (betre): An evaluation of the UKs highest recruiting, facilitated self-help waste minimisation project: Ackroyd, J. et al. Resources, Conservation and Recycling, 2003, 38, (4), 271–299. Journal Article
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
04/00474 CO2 emission abatement from fossil fuel power plants by exhaust gas treatment: Gambini, M. and Vellini, M. Journal of Engineering for Gas Turbines and Power, 2003, 125, (1), 365–373. Journal Article
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
Luo, R; Niu, J L
In: International Journal of Heat and Mass Transfer, 47 (10), pp. 2061 - 2072, 2004, ISSN: 0017-9310.
Water vapor diffusion and partition coefficients in cement slabs were determined by solving the inverse problem of one-dimensional unsteady mass diffusion based on measurements of the concentration of water vapor in a field and laboratory emission cell (FLEC) system. A solution for multi-process mass diffusion was obtained to analyze the influence of the non-uniform initial water vapor concentration distribution on the determination of diffusion and partition coefficients. The main factors affecting the accuracy of the diffusion and partition coefficients were discussed. Good agreement between the measured data and the predictions of the inverse problems showed that the mass diffusion in the cement slabs could be described accurately by the one-dimensional model.
04/00475 Effects of substrate parameters on the emissions of volatile organic compounds from wet coating materials: Zhang, L. Z. and Niu, J. L. Building and Environment, 2003, 38, (7), 939–946. Journal Article
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
04/00477 Estimating exposures in the asphalt industry for an international epidemiological cohort study of cancer risk: Burstyn, I. et al. American Journal of Industrial Medicine, 2003, 43, (1), 3–17. Journal Article
In: Fuel and Energy Abstracts, 45 (1), pp. 56, 2004, ISSN: 0140-6701.
04/00471 Beryllium in the environment: a review: Taylor, T. et al. Journal of Environmental Science and Health, Part A: Toxic/Hardous Substances & Environmental Engineering, 2003, A38, (2), 439–469. Journal Article
In: Fuel and Energy Abstracts, 45 (1), pp. 55 - 56, 2004, ISSN: 0140-6701.
Subject index Journal Article
In: Fuel and Energy Abstracts, 45 (1), pp. 71 - 78, 2004, ISSN: 0140-6701.