Charge distribution, dipole moments and molecular structure of some organogermanium compounds

Formal charge distributions in, and the electric dipole moments of, a few simple organogermanium compounds have been evaluated by the method of R. P. Smith et al. [J. Amer. Chem. Soc., 73(1951) 2263]. The difference between the experimental and calculated moments in the case of alkylhalogermanes is explained in terms of the pπ—dπ back bonding effect outweighing the electron releasing effect. In unsaturated compounds, the differences are attributed to possible mesmeric effects involving the expansion of the germanium valence shell.

Chemical mass closure and source-specific composition of atmospheric particles

It has been known for decades that particles can cause adverse health effects as they are deposited within the respiratory system. Atmospheric aerosol particles influence climate by scattering solar radiation but aerosol particles act also as the nuclei around which cloud droplets form. The principal objectives of this thesis were to investigate the chemical composition and the sources of fine particles in different environments (traffic, urban background, remote) as well as during some specific air pollution situations. Quantifying the climate and health effects of atmospheric aerosols is not possible without detailed information of the aerosol chemical composition. Aerosol measurements were carried out at nine sites in six countries (Finland, Germany, Czech, Netherlands, Greece and Italy). Several different instruments were used in order to measure both the particulate matter (PM) mass and its chemical composition. In the off-line measurements the samples were collected first on a substrate or filter and gravimetric and chemical analysis were conducted in the laboratory. In the on-line measurements the sampling and analysis were either a combined procedure or performed successively within the same instrument. Results from the impactor samples were analyzed by the statistical methods. This thesis comprises also a work where a method for the determination carbonaceous matter size distribution by using a multistage impactor was developed. It was found that the chemistry of PM has usually strong spatial, temporal and size-dependent variability. In the Finnish sites most of the fine PM consisted of organic matter. However, in Greece sulfate dominated the fine PM and in Italy nitrate made the largest contribution to the fine PM. Regarding the size-dependent chemical composition, organic components were likely to be enriched in smaller particles than inorganic ions. Data analysis showed that organic carbon (OC) had four major sources in Helsinki. Secondary production was the major source in Helsinki during spring, summer and fall, whereas in winter biomass combustion dominated OC. The significant impact of biomass combustion on OC concentrations was also observed in the measurements performed in Central Europe. In this thesis aerosol samples were collected mainly by the conventional filter and impactor methods which suffered from the long integration time. However, by filter and impactor measurements chemical mass closure was achieved accurately, and a simple filter sampling was found to be useful in order to explain the sources of PM on the seasonal basis. The online instruments gave additional information related to the temporal variations of the sources and the atmospheric mixing conditions.

Seasonal Greeting token 1983

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Stylized design of the Western Wall and the Mount above.

Seasonal Greeting token 1986

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: The monument to Jewish soldiers erected at the Jewish Martyrs Memorial Institute of Yad Vashem in Jerusalem.

Seasonal Greeting token 1993

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Stylized menorah, inscription.

Seasonal Greeting token 1978

Obverse: emblem of the Israel Government Coins and Medal Corporation. Reverse: Dove with spread wings.

Seasonal Greeting token 1998

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Stylized menorah with number fifty in the middle part.

Seasonal Greeting token 1994

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Three runners stylized, countryside in the background.

Seasonal Greeting token 2000

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Map from the15th century with Jerusalem as a center of the world.

Seasonal Greeting token 1999

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Menorah in the midddle of the zodiac symbols.

Seasonal Greetings Token 1979

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Building of the Israel Government Coins and Medal Corporation.

Seasonal Greeting token 1985

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Stylized view on Jerusalem.

Seasonal Greeting token 1987

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Dove of peace with olive branch in its beak.

Seasonal Greeting token 1989

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: Stylized menorah with number forty.

Seasonal Greeting token 1988

Obverse: Emblem of the Israel Government Coins and Medal Corporation. Reverse: The outline of Jerusalem with inscription.