Abstract. The interest in organic nitrogen and particularly in quantifying and studying the fate of amino acids (AAs) has been growing in the atmospheric-science community. However very little is known about biotic and abiotic transformation mechanisms of amino acids in clouds. In this work, we measured the biotransformation rates of 18 amino acids with four bacterial strains (Pseudomonas graminis PDD-13b-3, Rhodococcus enclensis PDD-23b-28, Sphingomonas sp. PDD-32b-11, and Pseudomonas syringae PDD-32b-74) isolated from cloud water and representative of this environment. At the same time, we also determined the abiotic (chemical, OH radical) transformation rates within the same solutions mimicking the composition of cloud water. We used a new approach by UPLC–HRMS (ultra-performance liquid chromatography–high-resolution mass spectrometry) to quantify free AAs directly in the artificial-cloud-water medium without concentration and derivatization. The experimentally derived transformation rates were used to compare their relative importance under atmospheric conditions with loss rates based on kinetic data of amino acid oxidation in the aqueous phase. This analysis shows that previous estimates overestimated the abiotic degradation rates and thus underestimated the lifetime of amino acids in the atmosphere, as they only considered loss processes but did not take into account the potential transformation of amino acids into each other.

γ -Al 2 O 3 nanoparticles have been synthesized by electrochemical method using a rectangular aluminum plate as the a node and aluminum plate as the cathode (counter electrode); both electrodes have the same shape and dimensions. TEM, and XRD have been used to characterize the nanoparticles. The results indicated that the size range of γ-Al 2 O 3 nanoparticles was (14-19) nanometers. Dealt with the studying of the effectiveness of the synthesized nanoparticles on the adsorption of cadmium ion from its aqueous solutions under different temperatures (10, 20, 30, 40, 50) • C, Also thermodynamic parameters (ΔS, ΔH, ΔG) were calculated. The equilibrium geometries of γ-Al 2 O 3 nanoparticles have been studied by Density function theory (DFT) using Gaussian 09 package program. The calculated highest-occupied molecular orbital energy (E HOMO ) is to be (-.04798 a.u) and the lowest-unoccupied molecular orbital energy (E LUMO ) is to be (0.05909 a.u). The calculated activation energy breakage γ-Al 2 O 3 -Cd was (35.529 kcal/ mole).

Abstract. The interest for organic nitrogen and particularly for quantifying and studying the fate of amino acids (AA) has been growing in the atmospheric science community. However very little is known about biotic and abiotic transformation mechanisms of amino acids in clouds. In this work, we measured the biotransformation rates of 18 amino acids with four bacterial strains (Pseudomonas graminis PDD-13b-3, Rhodococcus enclensis PDD-23b-28, Sphingomonas PDD-32b-11 and Pseudomonas syringae PDD-32b-74) isolated from cloud water and representative of this environment. At the same time, we also determined the abiotic (chemical, OH radical) transformation rates within the same solutions mimicking the composition of cloud water. We used a new approach by UPLC-HRMS to quantify free AA directly in the artificial cloud water medium without concentration and derivatization. The experimentally-derived transformation rates were used to compare their relative importance under atmospheric conditions and compared to the chemical loss rates based on kinetic data of amino acid oxidation in the aqueous phase. This analysis shows that previous estimates overestimated the abiotic degradation rates, and thus underestimated the lifetime of amino acids in the atmosphere as they only considered loss processes but did not take into account the potential transformation of amino acids into each other.

The article describes a new way to the synthesis of silver nanoparticles based on UV-irradiation energy. Our technique allows for producing high quality and clean nanoparticles. Moreover, our photolysis approach allows us to synthesis silver nanoparticles (Ag NPs) with very low cost and short time. The nanostructures were characterized using X-ray diffraction, transmission electron spectroscopy and UV-visible spectrometer. Most of the Ag NPs are shown to be a hexagonal shape and some of them are a spherical shape. The average size of nanoparticles was calculated to be around 20.23 nm. The morphology, size, and ion concentration of the synthesized Ag NPs determine their absorbance and transmittance at the UV region of spectrum. Silver's antimicrobial properties are well known and due to their antimicrobial activity, silver nanoparticles become more important. Therefore, our synthesized Ag NPs were used against Staphylococcus aureus (Gram-positive bacteria) and E. coli (Gram-negative bacteria). The results show that the nanoparticles at a concentration of 0.2 mg/ml demonstrated a high activity of antimicrobials, resulting in a good inhibition for both grams positive and negative bacteria. However, the effect of Ag NPs on gram-positive bacteria is higher than gram-negative bacteria.

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Abstract. The sinks of hydrocarbons in the atmosphere are usually described by oxidation reactions in the gas and aqueous (cloud) phases. Previous lab studies suggest that in addition to chemical processes, biodegradation by bacteria might also contribute to the loss of organics in clouds; however, due to the lack of comprehensive data sets on such biodegradation processes, they are not commonly included in atmospheric models. In the current study, we measured the biodegradation rates of phenol and catechol, which are known pollutants, by one of the most active strains selected during our previous screening in clouds (Rhodococcus enclensis). For catechol, biodegradation is about 10 times faster than for phenol. The experimentally derived biodegradation rates are included in a multiphase box model to compare the chemical loss rates of phenol and catechol in both the gas and aqueous phases to their biodegradation rate in the aqueous phase under atmospheric conditions. Model results show that the degradation rates in the aqueous phase by chemical and biological processes for both compounds are similar to each other. During day time, biodegradation of catechol is even predicted to exceed the chemical activity in the aqueous phase and to represent a significant sink (17 %) of total catechol in the atmospheric multiphase system. In general, our results suggest that atmospheric multiphase models may be incomplete for highly soluble organics as biodegradation may represent an unrecognized efficient loss of such organics in cloud water.

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