THE STEAM-JET AEROSOL COLLECTOR

A new principle of sampling aerosol particles by means of steam injection with the consequent collection of grown droplets has been established. An air stream free of water-soluble gases is rapidly mixed with steam. The resulting supersaturation causes aerosol particles to grow into droplets. The droplets containing dissolved aerosol species are then collected by two cyclones in series. The solution collected in the cyclones is constantly pumped out and can be on- or off-line analysed by means of ion chromatography or flow injection analysis. On the basis of the new sampling principle a prototype of an aerosol sampler was designed which is capable of sampling particles quantitatively down to several nanometres in diameter. The mass sampling efficiency of the instrument was found to be 99\%. The detection limit of the sampler for ammonium, sulphate, nitrate and chloride ions is below 0.7 mu g m(-3). By reduction of an already identified source of contamination, much lower detection limits can be achieved. During measurements the sampler proved to be stable, working without any assistance for extended periods of time. Comparison of the sampler with filter packs during measurements of ambient air aerosols showed that the sampler gives good results.

An approach to monitor the fraction of elemental carbon in the ultrafine aerosol

Attempts were made to measure the fraction of elemental carbon (EC) in ultrafine aerosol by modifying an Ambient Carbonaceous Particulate Monitor (ACPM, R&P 5400). The main modification consisted in placing a quartz filter in one of the sampling lines of this dual-channel instrument. With the filter all aerosol and EC contained in it is collected, while in the other line of the instrument the standard impactor samples only particles larger than 0.14 ��m. The fraction of EC in particles smaller than 0.14 ��m is derived from the difference in concentration as measured via the two sampling lines. Measurements with the modified instrument were made at a suburban site in Amsterdam, The Netherlands. An apparent adsorption artefact, which could not be eliminated by the use of denuders, precluded meaningful evaluation of the data for total carbon. Blanks in the measurements of EC were negligible and the EC data were hence further evaluated. We found that the concentration of EC obtained via the channel with the impactor was systematically lower than that in the filter-line. The average ratio of the concentrations was close to 0.6, which indicates that approximately 40% of the EC was in particles smaller than 0.14 ��m. Alternative explanations for the difference in the concentration in the two sampling lines could be excluded, such as a difference in the extent of oxidation. This should be a function of loading, which is not the case. Another reason for the difference could be that less material is collected by the impactor due to rebound, but such bounce of aerosol is very unlikely in The Netherlands due to co-deposition of abundant deliquesced and thus viscous ammonium compounds. The conclusion is that a further modification to assess the true fraction of ultrafine EC, by installing an impactor with cut-off diameter at 0.1 ��m, would be worth pursuing. �� 2005 Elsevier Ltd. All rights reserved.

Columnar aerosol properties in a northeastern atlantic site (plymouth united kingdom) by means of ground based skyradiometer data during years 2000-2008.

Between 2000 and 2008, columnar optical and radiative properties were measured at the Plymouth Marine Laboratory (PML), UK (50�� 21.95���N, 4�� 8.85���W) using an automatic Prede POM01L sun���sky photometer. The database was analyzed for aerosol optical properties using the SKYRAD radiative inversion algorithm and calibrated using the in situ SKYIL calibration method. Retrievals include aerosol optical depth, ��ngstr��m wavelength exponent, aerosol volume distribution, refractive index and single scattering albedo. The results show that the Plymouth site is characterized by low values of aerosol optical depth with low variability (0.18 �� 0.08 at 500 nm) and a mean annual ��ngstr��m exponent of 1.03 �� 0.21. The annual mean of the single scattering albedo is 0.97, indicative of non-absorbing aerosols. The aerosol properties were classified in terms of air mass back trajectories: the area is mainly affected by Atlantic air masses and the dominant aerosol type is a mixture of maritime particles, present in low burdens with variable size. The maritime air masses were defined by annual mean values for the AOD (at 500 nm) of 0.13���0.14 and a wavelength exponent of 0.96���1.03. Episodic anthropogenic and mineral dust intrusions occasionally occur, but they are sporadic and dilute (AOD at 500 nm about 0.20). Tropical continental air masses were characterized by the highest AOD at 500 nm (0.34) and the lowest wavelength exponent (0.83), although they were the least represented in the analysis.

Early target cells of measles virus after aerosol infection of non-human primates

Measles virus (MV) is highly infectious, and has long been thought to enter the host by infecting epithelial cells of the respiratory tract. However, epithelial cells do not express signaling lymphocyte activation molecule (CD150), which is the high-affinity cellular receptor for wild-type MV strains. We have generated a new recombinant MV strain expressing enhanced green fluorescent protein (EGFP), based on a wild-type genotype B3 virus isolate from Khartoum, Sudan (KS). Cynomolgus macaques were infected with a high dose of rMV(KS)EGFP by aerosol inhalation to ensure that the virus could reach the full range of potential target cells throughout the entire respiratory tract. Animals were euthanized 2, 3, 4 or 5 days post-infection (d.p.i., n?=?3 per time point) and infected (EGFP(+)) cells were identified at all four time points, albeit at low levels 2 and 3 d.p.i. At these earliest time points, MV-infected cells were exclusively detected in the lungs by fluorescence microscopy, histopathology and/or virus isolation from broncho-alveolar lavage cells. On 2 d.p.i., EGFP(+) cells were phenotypically typed as large mononuclear cells present in the alveolar lumen or lining the alveolar epithelium. One to two days later, larger clusters of MV-infected cells were detected in bronchus-associated lymphoid tissue (BALT) and in the tracheo-bronchial lymph nodes. From 4 d.p.i. onward, MV-infected cells were detected in peripheral blood and various lymphoid tissues. In spite of the possibility for the aerosolized virus to infect cells and lymphoid tissues of the upper respiratory tract, MV-infected cells were not detected in either the tonsils or the adenoids until after onset of viremia. These data strongly suggest that in our model MV entered the host at the alveolar level by infecting macrophages or dendritic cells, which traffic the virus to BALT or regional lymph nodes, resulting in local amplification and subsequent systemic dissemination by viremia.

A comprehensive aerosol spray method for the rapid photocatalytic grid area analysis of semiconductor photocatalyst thin films

Indicator inks, previously shown to be capable of rapidly assessing photocatalytic activity via a novel photo-reductive mechanism, were simply applied via an aerosol spray onto commercially available pieces of Activ (TM) self-cleaning glass. Ink layers could be applied with high evenness of spread, with as little deviation as 5% upon UV-visible spectroscopic assessment of 25 equally distributed positions over a 10 cm x 10 cm glass cut. The inks were comprised of either a resazurin (Rz) or dichloroindophenol (DCIP) redox dye with a glycerol sacrificial electron donor in an aqueous hydroxyethyl cellulose (HEC) polymer media. The photo-reduction reaction under UVA light of a single spot was monitored by UV-vis spectroscopy and digital images attained from a flat-bed scanner in tandem for both inks. The photo-reduction of Rz ink underwent a two-step kinetic process, whereby the blue redox dye was initially reduced to a pink intermediate resorufin (Rf) and subsequently reduced to a bleached form of the dye. In contrast, a simple one-step kinetic process was observed for the reduction of the light blue redox dye DCIP to its bleached intermediates. Changes in red-green-blue colour extracted from digital images of the inks were inversely proportional to the changes seen at corresponding wavelengths via UV-visible absorption spectroscopy and wholly indicative of the reaction kinetics. The photocatalytic activity areas of cuts of Activ (TM) glass, 10 cm x 10 cm in size, were assessed using both Rz and DCIP indicator inks evenly sprayed over the films: firstly using UVA lamp light to activate the underlying Activ (TM) film (1.75 mW cm(-2)) and secondly under solar conditions (2.06 +/- 0.14 mW cm(-2)). The photo-reduction reactions were monitored solely by flat-bed digital scanning. Red-green-blue values of a generated 14 x 14 grid (196 positions) that covered the entire area of each film image were extracted using a Custom-built program entitled RGB Extractor(C). A homogenous degradation over the 196 positions analysed for both Rz (Red colour deviation = 19% UVA, 8% Solar: Green colour deviation = 17% UVA, 12% Solar) and DCIP (Red colour deviation = 22% UVA, 16% Solar) inks was seen in both UVA and solar experiments, demonstrating the consistency of the self-cleaning titania layer on Activ (TM). The method presented provides a good solution for the high-throughput photocatalytic screening of a number of homogenous photocatalytically active materials simultaneously or numerous positions on a single film; both useful in assessing the homogeneity of a film or determining the best combination of reaction components to produce the optimum performance photocatalytic film. (C) 2010 Elsevier B.V. All rights reserved.

Combination aerosol therapy to treat Burkholderia cepacia complex

<p>Burkholderia cepacia infection in cystic fibrosis (CF) patients is associated with significant morbidity and mortality, yet no definitive treatment is currently available. This report describes a new approach to treat B. cepacia infection in CF patients, using a combination of amiloride and tobramycin aerosols. Four adults with the typical clinical syndrome of CF were recruited after repeated positive sputum cultures for B. cepacia. Aerosols of amiloride and tobramycin were given three times daily for 1-6 months, and repeated sputum cultures were collected to assess efficacy. Three of the four patients treated with the combined therapy eradicated B. cepacia from their sputum cultures for at least 2 yrs, and there were no adverse events. This novel combination may provide a new therapeutic option for Burkholderia cepacia infections. Furthermore, the strategy of combining antibiotics with ion transport agents may have ramifications for the treatment of other multi-resistant organisms.</p>

Distribui����o por tamanhos do aerosol atmosf��rico na Pen��nsula Ib��rica

Um dos principais fatores que afetam negativamente a qualidade do ambiente em muitas cidades em todo o mundo �� o material particulado (PM). A sua presen��a na atmosfera pode ter impactos negativos na sa��de humana, clima, patrim��nio edificado e ecossistemas. Muitos dos estudos realizados em ��reas urbanas focam apenas as fra����es respir��veis (PM10 e PM2,5). No entanto, os processos de forma����o, a identifica����o das fontes emissoras e os efeitos dependem muito da distribui����o granulom��trica das part��culas. A aten����o tem reca��do na an��lise de hidrocarbonetos poliarom��ticos (PAHs), devida �� sua carcinogenicidade e a informa����o dispon��vel sobre outros compostos �� escassa. O presente estudo consistiu na obten����o do PM distribu��do por diferentes fra����es de tamanho e na an��lise detalhada da sua composi����o qu��mica, em dois locais urbanos da Pen��nsula Ib��rica (Madrid e Lisboa). Dado que os ve��culos representam uma das principais fontes emissoras em ambientes urbanos, efetuou-se uma caracteriza����o mais detalhada deste tipo de emiss��es, conduzindo uma campanha de amostragem num t��nel rodovi��rio (Marqu��s de Pombal, Lisboa). As amostragens, em ambas as cidades, decorreram durante um m��s, quer no ver��o quer no inverno, em dois locais urbanos distintos, um junto a uma via com influ��ncia de tr��fego e outro numa ��rea urbana de fundo. No t��nel a amostragem foi realizada apenas durante uma semana. Em Madrid e no t��nel, o PM foi recolhido utilizando um amostrador de elevado volume com impactor em cascata com quatro tamanhos: 10-2,5, 2,5-0,95, 0,95-0,49 e < 0,49 ��m. Em Lisboa, foi utilizado um impactor em cascata com apenas dois tamanhos, 10- 2,5 e < 2,5 ��m. As amostras foram quimicamente analisadas e determinadas as concentra����es de compostos carbonados (OC, EC e carbonatos), i��es inorg��nicos sol��veis em ��gua (Cl���, NO3���, SO42���, Na+, NH4+, K+, Mg2+, Ca2+),metais e compostos org��nicos. Em Madrid, as concentra����es m��dias de PM10 foram 44 e 48% maiores nas amostras recolhidas junto �� estrada do que as de fundo urbano no ver��o e inverno, respetivamente. A fra����o grosseira e o PM0,5 apresentaram concentra����es mais elevadas no ver��o do que no inverno devido ��s condi����es climat��ricas pouco usuais. No ver��o, as amostragens decorreram num m��s em que as temperaturas foram muito elevadas e em que ocorreram v��rios epis��dios de intrus��o de poeira africana. Durante o per��odo de amostragem de inverno, as temperaturas foram muito baixas e registaram-se v��rios dias de precipita����o quer sob a forma de chuva, quer sob a forma de neve. As situa����es meteorol��gicas sin��ticas mais comuns, incluindo aquelas que causam o transporte de massas de ar com poeiras Africanas, foram identificadas em ambas as esta����es do ano. As concentra����es m��ssicas de PM10, EC e OC foram encontrados predominantemente na fra����o de tamanho ultrafino em ambos os locais de amostragem e esta����es do ano. Nas restantes fra����es n��o se observou nenhuma tend��ncia sazonal. O carbono org��nico secund��rio (SOC) mostrou um claro padr��o sazonal, com concentra����es muito mais elevadas no ver��o do que no inverno, em ambos os lugares. A partir do balan��o m��ssico de i��es, observou-se que, no ver��o, a forma����o de compostos inorg��nicos secund��rios (SIC) conduziu a um enriquecimento pouco comum de Ca2+ na fra����o submicrom��trica, quer nas amostras de tr��fego, quer em fundo urbano. Os alcanos, PAHs, os ��lcoois e os ��cidos foram as classes de compostos org��nicos identificados e quantificados no material particulado. Globalmente, representaram 0,26 e 0,11 ��g m���3 no ver��o e inverno, respetivamente, no local de tr��fego e 0,28 e 0,035 ��g m���3 na ��rea urbana de fundo. Os diferentes compostos org��nicos tamb��m apresentaram padr��es sazonais, sugerindo fontes de emiss��o (e.g. escapes dos ve��culos e fontes biog��nicas) ou processos de forma����o com contribui����es vari��veis ao longo do ano. As concentra����es de benzo���a���pireno equivalente foram menores que 1 ng m-3 e o risco carcinog��nico estimado �� baixo. No ver��o, os maiores enriquecimentos de metais ocorreram na fra����o submicrom��trica, e no inverno na fra����o grosseira. No ver��o, os enriquecimentos foram ��� 80% para o Mn, Ni, Cu, Zn, Cd, Sb e Co, no inverno, estes tra��adores de emiss��es do tr��fego foram menores, exceto para o Zn. Em Lisboa, a concentra����o m��dia de PM10 foi de 48 ��g m-3 no ver��o e de 44 ��g m-3 no inverno, junto �� estrada. Na ��rea de fundo urbano, registaram-se n��veis compar��veis nas duas esta����es (27 ��g m-3 e 26 ��g m-3). A m��dia do r��cio PM2,5/PM10 foi de 65% no ver��o e 44% no inverno na ��rea de tr��fego e 62% e 59% na ��rea urbana de fundo. Estes resultados significam que o PM2,5 �� um dos principais contaminantes que afetam a qualidade do ar no centro da cidade de Lisboa. A rela����o OC/EC, que reflete a composi����o das emiss��es de combust��o dos ve��culos, variou entre 0,3 e 0,4 no interior do t��nel. Os r��cios de OC/EC m��nimos obtidos junto ��s vias de tr��fego em Madrid e em Lisboa encontram-se entre os do t��nel e os registados em atmosferas urbanas de fundo, sugerindo que os valores m��nimos habitualmente obtidos para este par��metro em ambientes urbanos abertos sobrestimam as emiss��es diretas de OC pelo transporte rodovi��rio. Espera-se que os resultados deste trabalho contribuam para suprir, pelo menos em parte, as lacunas de informa����o quer sobre a composi����o de v��rias granulometrias de PM, quer sobre fontes e processos de forma����o em atmosferas urbanas. Como a exposi����o a poluentes do ar ultrapassa o controle dos indiv��duos e exige a����o das autoridades p��blicas a n��vel nacional, regional e at�� mesmo internacional, �� importante propor medidas mitigadoras focadas nas principais fontes de emiss��o identificadas.