Studies of the growth and size distribution of aerorosol particles

A study is made of the theoretical growth of soluble aerosol particles with increasing humidity. The growth equation is applied to sodium chloride and ammonium sulphate particles, chosen because of their special significance as atmospheric nuclei. The effect of particle growth on visibility is also considered. An experimental investigation of the effect of humidity on particle size is carried out using artificially generated aerosols of sodium chloride and ammonium sulphate. Inaddition a study is made of the variation in the particle size distribution of the atmospheric aerosol measured continuously over a 49 day period at Durham Observatory. A theoretical growth relation, based on Mason's equation (1971) relating the size of a solution droplet to the relative humidity of its environment, is derived. Novel approximations are incorporated in the application of the growth equation to particles of sodium chloride and ammonium sulphate and the results for sodium chloride agree with Mason’s equation to within 0.5% over the dry particle mass range from 3 x l0(^-17) g to 3 x 10(^-11) g. The predicted growth of ammonium sulphate particles with relative humidity indicates agreement with previous work, by Garland (1969). Experimental measurements were made of the growth of sodium chloride ammonium sulphate nuclei with humidity. The particles with initial radius between 2 x 10(^-6) and 3 x 10(^-6) were generated by a collison atomizer and allowed to grow in a storage vessel as the humidity was increased from about 60% to 92% The experimental measurements agree well with the theoretical growth curves, chosen to correspond as closely as possible to the experimental particle size at the lowest humidity. Average percentage increases in the particle radius of 60% and 95% for ammonium sulphate and sodium chloride particles of initial average radii of 3.0 x 10(^-6)cm and 2.6 x 10(^-6)cm respectively were obtained as the humidity was increased from about 60% to 92%. Approximations to Mie's theory of light scattering were used to calculate the extinction coefficient, σ, for monodisperse aerosols of sodium chloride and ammonium sulphate as a function of solute mass per particle in the range between 3 x 10(^-17)g and 3 x 10(^-11)g at humidities of 80%, 95% and 99%. The results indicate that the sodium chloride particles are more efficient in reducing visibility than ammonium sulphate particles by factors varying from about 1.3 to 5.5 over the whole range of humidity and dry particle mass. Calculations show that, for both salts, a Junge particle size distribution is about twice as effective at reducing visibility as a monodisperse aerosol of the same salt with particle radius equal to the mass median of the Junge distribution, A study of the variation in the particle size distribution of the atmospheric aerosol in the radius range 0.25 - 5.0 micrometres, measured at Durham Observatory over a period of 49 days from 21 July to 8 September 1975, indicates that the distribution closely follows the shape of a Junge log-radius distribution with a slope, β, equal to 3.04, The average diurnal variation over the period shows maximum and minimum number concentration occurring between 0200 and 0800 hours B.S.T. and 1400 and 2000 hours B,S.T. respectively. The general increase in the particle number concentration, particularly in the lower size ranges, during the period 0000 to 0600 can be partly attributed to an increase in humidity. This is reflected in the positive correlation coefficient between particle number concentration and relative humidity

Comprehensive multivariate correlations between climatic effect, metabolite-profile, antioxidant capacity and antibacterial activity of Brazilian red propolis metabolites during seasonal study

The standardization of apiceutical products like as propolis extracts has been widely debated worldwide and variations in the propolis chemical composition are still very relevant topics for use-standardized of different propolis-type as medication by much of the world’s population. The present manuscript discuss important issues related to the climate effect and variations in propolis metabolite-profiling changes, antioxidant capacity and variations of the antibacterial activity of the Brazilian red propolis metabolites using comprehensive multivariate correlations. It was observed the increasing of guttiferones concentrations during the intense drought period and drastic decreasing in rainy period. The climate variation induced the high concentration of flavonoids in rainy period with pronounced dropped in some rainy months. The Pearson´s analysis demonstrated correlation between IC50 from DPPH and guttiferones and flavonoids concentrations. The PCA-X and Hotelling T2 test showed outliers during the months with lowest concentrations of formononetin and isoliquiritigenin was observed in antibacterial tests. The PLS-DA, OPLS-DA and VIP analysis demonstrate guttiferone E, guttiferone B, liquiritigenin, naringenin are considered important substances responsible by anti-staphylococcal activity in red propolis composition during the rainy season and drought period, but a synergistic effect with other flavonoids and isoflavonoids are not ruled out

The Japanese Market for U.S. High-Value Products: Effects of the GATT-11 Agreement

This study examines the effects of the 1988 GATT-11 Agreement on U.S. exports to Japan. The agreement was reached by the General Agreement on Tariffs and Trade (GATT) after bilateral negotiations between Japan and the United States broke down. The commodities covered under the agreement include a diverse group of semiprocessed, high-value agricultural products (HVPs). During the 6- year period 1988-93, Japanese imports of these commodities increased substantially, and imports from the United States increased around $100 million. The agreement, therefore, has been beneficial to the United States as well as other suppliers. In Japan, the growing difficulty of relying on domestic suppliers is encouraging retailers to look abroad for many types of high-value products. During the next decade, the list of products needed by Japan is expected to expand far beyond the original GATT-11 commodities

High-Value Products: Growing U.S. and EC Competition in World Markets

This study examines competition between the U.S. and the European Community (EC) in world markets for high-value agricultural products (HVPs). The EC and the United States are the world's largest exporters of HVPs. A comparison of U.S. and EC •export shares during 1970-87 shows that the EC; the world's leading exporter of high-value products, has successfully competed against the United States for a number of leading processed products including dairy products, meat, and flourd EC agricultural exports have benefited for many years from subsidies which make their HVP exports competitive in world markets. The United States, with its plentiful supply of high-quality, low-priced inputs and efficient processing capacity has the potential for increasing its share of the HVP market. While U.S. policy changes authorized under the 1985 Farm Bill and the lower dollar have bOosted U.S. HVP exports; future expansion will depend upon U.S. competitiveness and changes in foreign demand

Lights Out.

Illustration of the silhouette of a soldier playing a trumpet among tents. Photo of a man.https://scholarsjunction.msstate.edu/cht-sheet-music/4580/thumbnail.jp