Light-absorbing non-refractory aerosol particles may contribute significantly to total aerosol absorption of solar radiation and have been observed with a new method associated with the NOAA ...Single-Particle Soot Photometer (SP2). The SP2 was designed to measure incandescence from refractory carbon in individual particles sampled from ambient or laboratory air samples. Although light-absorbing non-refractory particles do not incandesce, they lose mass while transiting the SP2 laser beam. This loss of mass is detected by the asymmetry produced in the particle scattering signal. Air sampled on board the NOAA WP-3D research aircraft during the TexAQS/GoMACCS campaign were examined for evidence of light-absorbing non-refractory particles. These particles are found in some plumes sampled during the campaign and are compared to the abundance of refractory black carbon particles.
The synthesis and characterisation of three novel reagents for use in the radioallergosorbent test (RAST) for the diagnosis of penicillin allergy are described. The antigenic determinants involved ...are the benzyl penicillanyl, thiol-linked benzyl penicillenate and thiol-linked penicillamine. These reagents, and also one specific for the benzyl penicilloyl group, have been used to evaluate the sea of subjects suspected of suffering from penicillin allergy and to explore the aetiology of the respiratory dyspnoea experienced by some workers exposed to penicillin-containing dusts. The use of these reagents, while confirming the importance of the penicilloyl or major determinant of penicillin allergy, has shown that there is heterogeneity in the IgE response of penicillin-allergic patients and some patients have IgE antibody specific for one or more of the new determinants only. These reagents will, therefore, increase diagnostic capabilities. Their use has also confirmed that the disorder induced by occupational exposure to penicillins is not primarily mediated by IgE antibody specific for allergenic determinants represented by any of the available reagents.
There is increasing evidence for the role of basophils in the allergen-induced late asthmatic response (LAR). To study the effect of inhaled allergen on basophil function in subjects with asthma, ex ...vivo basophil spontaneous histamine release (SHR) in peripheral blood and plasma histamine was measured before and 2, 5, 10, and 15 minutes, and 2, 4, 6, and 8 hours after allergen bronchial challenge (allergen study day) in six subjects with atopic asthma. Allergen inhalation induced an early response and LAR consisting of a mean (+/- SD) 32.5% (+/- 7.9%) and 28.8% (+/- 7.7%) fall in FEV1, respectively. As a control for the effects of bronchoconstriction, on another occasion, methacholine challenge was performed to produce a mean 33.4% (+/- 3.4%) fall in FEV1 during the early response and no LAR, and blood was obtained to measure basophil histamine release (HR) and plasma histamine. There was a small, but significant (p less than 0.05), rise in median SHR from 4.6% to 6.1% of total basophil histamine after allergen but not after methacholine inhalation. HR remained high after allergen inhalation during the 8 hours of study, whereas it demonstrated a steady, significant, decrease between 4 to 8 hours after methacholine inhalation. No significant changes in plasma histamine were recorded on either allergen or methacholine study days. On a third occasion, SHR was measured after challenge with physiologic saline to control for any effects of methacholine on SHR, and a decrease in HR was recorded during the day similar to HR observed after methacholine challenge. These studies suggest an enhancing effect of inhaled allergen on SHR.
Tropospheric ozone (O3) is a key compound influencing urban air quality. It is produced by the reaction of oxygen atoms (O) with oxygen molecules (O2). In the troposphere, oxygen atoms are primarily ...produced by photolysis of nitrogen dioxide (NO2). The presence of aerosols, in particular black carbon (BC), has previously been shown to reduce nitrogen dioxide photolysis rates. It has been suggested that ozone concentrations can be reduced by up to 20% because of the reduction in photolysis rates by BC. In this work, we will present results from the NOAA WP-3 research aircraft participating in the 2006 Texas Air Quality Study (TEXAQS2006). On board the aircraft, spectral actinic fluxes from 280 to 690 nm were measured at 1 Hz using a spectroradiometer. Photolysis rates of 19 compounds, including nitrogen dioxide and ozone, were calculated from the spectral actinic fluxes. Black carbon mass concentrations were measured at 1 Hz using a Single-Particle Soot Photometer (SP2). Photolysis rates were reduced by up to 30% under high BC mass loadings during the measurement campaign. Box model calculations of the tropospheric ozone chemical mechanism, including various precursors, e.g. CO, NO, and NO2, help to describe how these significant reductions in photolysis rates influenced ozone production rates during TEXAQS2006. We will also discuss the impact of black carbon on photolysis rates and ozone production in urban areas in general.
Measurements were made of light-scattering from individual particles containing black carbon (BC) using a single particle soot photometer (SP2) integrated on board a NASA WB-57F high altitude ...research aircraft. The measurements were made during January and February 2006 at altitudes from near the surface to 19 km and at latitudes from 40circN to the equator. The BC mass of each particle was measured over the range ~0.1 - 0.6 mum BC volume equivalent diameter. The mixing state of each particle was inferred from light-scattering characteristics, with a detection limit equivalent to a ~40 nm coating of dry sulfate. We observed strongly contrasting mixing states for BC in the lower stratosphere versus the troposphere. Mie calculations were used to derive the coating thickness, single-scatter albedo, and enhanced light absorption for individual particles. These results provide important observations of the mixing state of black carbon particles in the tropical troposphere and lower stratosphere and, hence, represent important constraints on BC removal rates and lifetimes in global aerosol models.
Radioallergosorbent tests (RAST) using urinary proteins from mice, rats, guinea pigs and rabbits have been developed and used in the diagnosis of laboratory animal allergy (LAA). Of the 273 subjects ...tested, 15 had been previously diagnosed as laboratory animal allergic and 8 of these (53%) gave one or more positive RAST results. Of the 258 symptom-free individuals, only 9 (3.5%) had one or more positive RAST. Of these 9, 7 had previously worked with animals or had occupational exposure to the appropriate species; the remaining 2 individuals had only some pet exposure. RAST was, therefore, of value in the diagnosis of LAA. During the development of these RAST assays, several sources of potential error were identified. Modest titres of total IgE (600 IU/ml and above) were found to influence the specific RAST index observed and lead to false positive results. The presence of human IgG antibody specific for rabbit serum proteins was also identified in four sera, and was responsible for interference in the rabbit urinary protein RAST system.
Size-resolved, non-refractory (NR) aerosol composition was measured on a 10-second basis and with high sensitivity aboard the NOAA WP-3D aircraft using an Aerodyne Compact Time-of-Flight Aerosol Mass ...Spectrometer (C-ToF AMS) during the 2006 Texas Air Quality Study/Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS/GoMACCs). Fine features in the C-ToF AMS data were highly correlated with independent measurements of submicron aerosol volume and dry extinction. There are emissions of several secondary aerosol precursors in the Houston area: sulfur dioxide (SO2) from industrial facilities and isolated power plants as well as volatile organic compounds (VOCs) from industrial facilities mainly along the ship channel and from other urban sources. Downwind of Houston, there is a clear progression of increasing aerosol mass as a function of distance, with both sulfate and organic material being formed. However, the complexity of the Houston area sources produces an inhomogeneous composition of the aerosol downwind, also depending on the upwind source. Since the sources of SOA (secondary organic aerosol) precursors cover a large area whereas SO2 is emitted from point sources, the urban area generally produces broadly distributed SOA with narrow, high mass concentrations of sulfate aerosol in the first several hours downwind. In contrast, Dallas is more typical of urban areas with VOCs from mobile emissions as the main precursor of secondary aerosol. Hence, downwind of Dallas the aerosol is more homogeneous in composition and primarily organic. The hygroscopic and optical properties of the aerosol, as it is transformed downwind of both urban areas, will also be discussed.
Myocardial protection provided by 2 types of cold cardioplegic solution and by cold saline solution was compared experimentally in dogs on cardiopulmonary bypass. Techniques and solutions used ...simulated clinical conditions. Serial biopsies of myocardium were assayed for adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate. Maintenance and recovery of each phosphate was calculated as a percentage of the prebypass value for each type of solution; these values were used to compare the myocardial protection afforded by the 3 solutions. A difference in these values was not observed between the 2 types of cardioplegic solution; both values were greater than for the control solution, which may indicate improved myocardial protection with cardioplegic arrest.
Formation of particulate matter is common in areas with high emissions of volatile organic compounds (VOCs), NOx, and SO2. These particles have lifetimes of days to weeks, and thus can have both ...local and regional effects on visibility, air quality, and human health as well as direct and indirect effects on climate. During TexAQS 2006, mass concentrations of non-refractory inorganic species (sulfate, ammonium, and nitrate) and total organics in submicron aerosols were measured by a Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) onboard the NOAA WP-3D aircraft. In this presentation, we analyze composition changes of organic aerosols in different air masses. We examine organic mass spectra along with simultaneous measurements of VOCs and their oxidation products in order to determine the contribution of anthropogenic and biogenic sources to the aerosol organic mass. These measurements were performed in plumes intercepted during the daytime north of Houston where large isoprene emissions were observed. Furthermore, the fresh hydrocarbon-like (HOA) and processed oxygenated-like organics (OOA) fractions of the total organic aerosol mass in several plumes transected during daytime and nighttime are presented and compared. We will also discuss differences in correlations between organic aerosol composition markers and primary or secondary gas-phase species in different plumes.
