Secondary Organic Aerosol Composition Studies Using Mass Spectrometry

Trace volatile organic compounds emitted by biogenic and anthropogenic sources into the atmosphere can undergo extensive photooxidation to form species with lower volatility. By equilibrium partitioning or reactive uptake, these compounds can nucleate into new aerosol particles or deposit onto already-existing particles to form secondary organic aerosol (SOA). SOA and other atmospheric particulate matter have measurable effects on global climate and public health, making understanding SOA formation a needed field of scientific inquiry. SOA formation can be done in a laboratory setting, using an environmental chamber; under these controlled conditions it is possible to generate SOA from a single parent compound and study the chemical composition of the gas and particle phases. By studying the SOA composition, it is possible to gain understanding of the chemical reactions that occur in the gas phase and particle phase, and identify potential heterogeneous processes that occur at the surface of SOA particles. In this thesis, mass spectrometric methods are used to identify qualitatively and qualitatively the chemical components of SOA derived from the photooxidation of important anthropogenic volatile organic compounds that are associated with gasoline and diesel fuels and industrial activity (C12 alkanes, toluene, and o-, m-, and p-cresols). The conditions under which SOA was generated in each system were varied to explore the effect of NO_x and inorganic seed composition on SOA chemical composition. The structure of the parent alkane was varied to investigate the effect on the functionalization and fragmentation of the resulting oxidation products. Relative humidity was varied in the alkane system as well to measure the effect of increased particle-phase water on condensed-phase reactions. In all systems, oligomeric species, resulting potentially from particle-phase and heterogeneous processes, were identified. Imines produced by reactions between (NH₄)₂SO₄ seed and carbonyl compounds were identified in all systems. Multigenerational photochemistry producing low- and extremely low-volatility organic compounds (LVOC and ELVOC) was reflected strongly in the particle-phase composition as well.

Chemical composition of Iraq water resources (abbreviated translation) [Translation from: Vodnye Resursy 1975(4,) 173-185]

This abbreviated translation summarises the chemical composition of Iraq water resources. Among the described water bodies are the River Euphrates, Shatt al Arab River and a number of standing waters.

Species composition and relative abundance of zooplanktivorous haplochromines in the northern portion of Lake Victoria (Uganda)

Recent surveys have indicated an increase in haplochromine biomass recorded from the bottom trawl and in the beam trawl. The haplochromines recovering in the offshore waters belong to three species in the zooplanktivorous trophic group: Yssichromis laparogramma (Greenwood and Gee), Yssichromis fusiformis (Greenwood and Gee) and Astatotilapia lacrimosa (Boulenger). In this paper, the species composition and relative abundance of the zooplanktivorous haplochromines recorded from the bottom and frame trawl surveys in the various parts of the Ugandan waters of Lake Victoria are discussed.

Composition and bulk properties of Dorset river gravels

Considerable interest has been expressed in the composition of the stream gravels, the movement of bed materials and the relationship of sediment composition, packing and siltation of void space to invertebrate ecology. In the autumn of 1982, freeze-samples of gravel were obtained in Dorset streams. Data were required on the depth of salmonid egg pocke and were part of a broader investigation of regional variation in the independent variables of salmonid fish length, gravel size, current velocity and the resultant dependent variable ~egg burial depth. The Dorset river gravels examined are bimodal. The grain size distribution may be resolved into two near-normal frequency distributions interpreted as representing a primary framework or lattice of gravel particles into which a secondary matrix population of sand particles has penetrated.

Changes in the phytoplankton

An article discussing changes observed in phytoplankton of the Lake District. An overview is given of previous phytoplankton studies undertaken in the area, detailing some changes found in various waterbodies. Water quality changes in Lake Windermere are mentioned, including the gradual increase of dissolved organic matter (DOM), believed to be caused by the increase of sewage to the lake. The lakes in the Alps are given as an example of a similar anthropogenic pollution scenario. The treatment of a Lake District tarn with bone meal is described. The article goes on to discuss the composition of plankton throughout the year under a variety of climatic conditions. A figure shows seasonal variation in the consistuents of phytoplankton in Windermere (north basin).

The changing chemical composition of chalk streams and rivers

The area studied was the River Frome system below Dorchester. The main river has its origins mainly in chalk springs, although some of its tributaries have surface run-off from farm lands and heath-lands. Thus the chemistry of the river is affected by changes in land practice and differences in the geology of the catchment area. Regular chemical analysis of chalk waters started at the River Laboratory in 1964, Regular weekly analyses have been carried out since 1965 at Bere Stream (a small chalk stream) and the River Frome (a large chalk stream); also single samples have been analysed to provide preliminary information. In 1970-71 an attempt was made to discover the contribution each main source made to the flow and chemical composition of the River Frome. Results of these investigations are presented in the paper.

Analysing the contribution of ATM/ATR pathway activation in establishing the premature senescence of E2F1/E2F2-/- bone-marrow-derived macrophages

E2F1 and E2F2 transcription factors have an important role during the regulation of cell cycle. In experiments done with E2F1/E2F2 knockout mice, it has been described that bone-marrow-derived macrophages (BMDM) undergo an early rapid proliferation event related to DNA hyper-replication. As a consequence, DNA damage response (DDR) pathway is triggered and E2F1/E2F2 knockout macrophages enter premature senescence related to G2/M phase arrest. The exact mechanism trough which DNA hyper-replication leads to DDR in absence of E2F1 and E2F2 remains undiscovered. To determine whether the ATR/ATM pathway, the master regulator of G2/M checkpoint, might be the surveillance mechanism in order to regulate uncontrolled proliferation in the DKO model, we monitored and analysis biochemical properties of BMDM cultures in the presence of caffeine, a potent inhibitor of ATM/ATR activity. Our results show that the addition of caffeine abolishes premature senescence in DKO BMDM, stimulates γ-H2AX accumulation and decreases Mcm2 expression.

Aspects of the washout of salmonid eggs. 6. Information on gravel composition , redd sites, the dimensions of redds and the depth of egg burial

Sampling was concentrated on the North Moor region and the series of ditches which drained this area to the Bristol Channel. Although most ditches were not deep the mud substratum precluded sampling from within the habitat. All samples were taken with a pond net from the banks. Efforts were made to sample each part of the habitat although in some ditches the macrophyte growth was so intense as to make sampling difficult particularly of the sediments. Organisms were identified on the 10 sampling sites.

Size composition of the catches of the pink shrimp Penaeus duorarum notialis in the shrimp fishery of Sierra Leone

Measurements were taken of size distribution of P. d. notialis collected off Sierra Leone over a period of six months from October 1977 to March 1978. From the frequency distribution curves it is observed that the curves for male shrimps show only one or two major modes, which show prominence between 12.5 and 14.1 cm of total length. Females mostly exhibited size groups with three or four different length ranges and occasional occurrence of 1 to 5 modes. These size groups were observed to show continuous changes. No one group could be said to be permanent. The point of entry into the fishery of male shrimps was found to be at an average total length of 10.5 cm, while females did so at 11 cm. Sex ratios in the different samples were usually 1:1 but in one case the males were more numerous by 2:1 and in four other samples females were significantly preponderent. These departures from the 1:1 ratio may have been artificially created by sorting of the catches on board the ships.

Effect of alkaline-earth metal composition on spectroscopic properties of Er3+ in fluorophosphate glasses

Optical spectroscopic properties of Er3+-doped alkaline-earth metal modified fluoropho sphate glasses have been investigated experimentally for developing broadband fiber and planar amplifiers. The results show a strong correlation between the alkaline-earth metal content and the spectroscopic parameters such as absorption and emission cross sections, full widths at half-maximum and Judd-Ofelt intensity parameters. It is found that strontium ions could have more influences on the Judd-Ofelt intensity parameters and the absorption and emission cross sections than other alkaline-earth metal ions such as Mg2+, Ca2+, Ba2+. The sample containing 23 mol% strontium fluoride exhibits the maximum emission cross section of 7.58 x 10(-21) cm(2), the broadest full width at half-maximum of 65 nm and the longer lifetime of 8.6 ms among the alkaline-earth metal modified fluorophosphates glasses studied. The Judd-Ofelt intensity parameter Omega(6)s, the emission cross sections and the full widths at half-maximum in the Er3+-doped fluorophosphate glasses studied are larger than in the silicate and phosphate glasses.

Composition dependent frequency upconversion luminescence in Er3+-doped oxychloride germanate glasses

Er3+ -doped oxychloride germanate glasses have been synthesized by conventional melting and quenching method. Structural and thermal stability properties were obtained based on the Raman spectra and differential thermal analysis, indicating that PbCl2 plays an important role in the formation of glass network and has an important influence on the maximum phonon energy and thermal stability of host glasses. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), and F-4(9/2) -> I-4(15/2), respectively, were observed at room temperature. With increasing PbCl2 content, the intensity of green (525 and 546 nm) emissions increases significantly, while the red (657 nm) emission increases slowly. The results indicate that PbCl2 has more influence on the green emissions than the red emission in oxychloride germanate glasses. The possible upconversion luminescence mechanisms has also been estimated and discussed. (c) 2005 Elsevier Ltd. All rights reserved.