The photooxidation of methyl pheophorbides, derived from bacteriochlorophyll c, yields ring-opened acetylbilitrienes which are structurally related to mammalian bile pigments. The mechanism of this photooxidation, and that of certain mesomethyl-substituted model compounds, has been studied using 18O labeling with molecular oxygen. In all cases, the methine bridge carbon atoms were retained in t...

[1] The oxidation of isoprene (2-methyl-1,3-butadiene) is known to play a central role in the photochemistry of the troposphere, but is generally not considered to lead to the formation of secondary organic aerosol (SOA), due to the relatively high volatility of known reaction products. However, in the chamber studies described here, we measure SOA production from isoprene photooxidation under ...

A series of outdoor chamber experiments has been used to establish and characterize the significant atmospheric aerosol-forming potentials of the most prevalent biogenic hydrocarbons emitted by vegetation. These compounds were also studied to elucidate the effect of structure on aerosol yield for these types of compounds. Because oxidation products partition between the gas and aerosol phases, ...

[1] Molecular level characterizations of dissolved lignin were conducted in Mississippi River plume waters to study the impact of various removal mechanisms (photooxidation, microbial degradation, and flocculation) on dissolved organic material (DOM) concentrations and compositions. Prior to analysis, dissolved (<0.2-mm pore size) samples were size fractionated by ultrafiltration into high mole...

Analyzing cell morphology is crucial in the fields of cell biology and neuroscience. One of the main methods for evaluating cell morphology is by using intracellular fluorescent markers, including various commercially available dyes and genetically encoded fluorescent proteins. These markers can be used as free radical sources in photooxidation reactions, which in the presence of diaminobenzidi...

A new denuder-filter sampling technique has been used to investigate the gas/particle partitioning behaviour of the carbonyl products from the photooxidation of isoprene and 1,3,5-trimethylbenzene. A series of experiments was performed in two atmospheric simulation chambers at atmospheric pressure and ambient temperature in the presence of NOx and at a relative humidity of approximately 50%. Th...

An investigation of the effect of relative humidity on aerosol formation from m-xylene and 1,3,5-trimethylbenzene photooxidation is reported. Experiments were performed in the presence and absence of ammonium sulfate seed particles (both aqueous and dry) to ascertain the effect of partitioning of oxidation products into a strong electrolytic solution or onto dry crystalline seed particles. In m...

tio2 nanoparticles, as a photocatalyst for oxidation of dimethyl methylphosphonate (dmmp) as an organophosphorus simulant of chemical warfare agent, were prepared by using sol-gel method. the prepared nanoparticles were then modified with transition metals in order to decrease the electron-hole recombination and increase the photocatalytic activity. transition metal ions including pt, pd and ni...

Objective: The objective of the present study to investigate photooxidation of PC in presence of thermally generated triplet excited ketones and in presence of photosensitizers rose bengal and riboflavin. Methods: The Photooxidation of antiviral drug penciclovir was studied under different reaction conditions. First we treated the penciclovir (PC 1) with triplet excited ketones, which have been...