Transduction of light dependent signals to redox sensitive kinases in photosynthetic membranes modulates energy transfer to the photochemical reaction centres and regulates biogenesis, stability and turnover of thylakoid protein complexes. The occupancy of the quinol-oxidation site of the cytochrome bf complex by plastoquinol and the redox state of protein thiol groups act as elements of the si...

The photochemical oxidation of Fe(2+) -hydroxide complexes dissolved in anoxic Precambrian oceans has been suggested as a mechanism to explain the deposition of Banded Iron Formations (BIFs). Photochemical studies have not yet addressed the low levels of manganese in many of these deposits, which probably precipitated from solutions bearing similar concentrations of Fe2+ and Mn2+. Depositiona...

The presence of aromatic residues and their close spatial proximity to disulphide bridges makes hen egg white lysozyme labile to UV excitation. UVB induced photo-oxidation of tryptophan and tyrosine residues leads to photochemical products, such as, kynurenine, N-formylkynurenine and dityrosine and to the disruption of disulphide bridges in proteins. We here report that lysozyme UV induced phot...

7.11.5.1 Thermal and Photochemical Reactions 405 7.11.5.2 Reactions with Electrophiles 406 7.11.5.2.1 N-Alkylation 406 7.11.5.2.2 C-Allcylation and arylation 408 7.11.5.2.3 Reaction with diazonium ions 409 7.11.5.2.4 Oxidation of ring atoms 409 7.11.5.2.5 Halogenation 410 7.11.5.2.6 Metal complexes 410 7.11.5.3 Reactions with Nucleophiles 411 7.11.5.3.1 Reduction 411 7.11.5.3.2 Amination and hy...

We have investigated an aerosol processing and evolution event from 21–22 July during the summer 2009 Field Intensive Study at Queens College in New York City (NYC). The evolution processes are characterized by three consecutive stages: (1) aerosol wet scavenging, (2) nighttime nitrate formation, and (3) photochemical production and evolution of secondary aerosol species. Our results suggest th...

Advanced Oxidation Processes (AOP) using ozone, H2O2, ultrasound (US), ultraviolet radiation (UV), Fenton’s reagent (FeII+H2O2) alone or in combination involving hydroxyl radicals are considered as possible methods of clean and ecologically safe remedial treatment for the degradation of organics. In the present study, comparison of kinetics of photochemical, sonochemical and chemical oxidation ...

Isoprene hydroxynitrates (IN) are tracers of the photochemical oxidation of isoprene in high NOx environments. Production and loss of IN have a significant influence on the NOx cycle and tropospheric O3 chemistry. To better understand IN chemistry, a series of photochemical reaction chamber experiments was conducted to determine the IN yield from isoprene photooxidation at high NO concentration...

Atmospheric brown carbon (BrC) is a collective term for light absorbing organic compounds in the atmosphere. While the identification of BrC and its formation mechanisms is currently a central effort in the community, little is known about the atmospheric removal processes of aerosol BrC. As a result, we report on a series of laboratory studies of photochemical processing of BrC in the aqueous ...

Abstract. From the Archean toward Proterozoic, Earth's atmosphere underwent a major shift from anoxic to oxic conditions at around 2.4 2.1 Ga known as Great Oxidation Event (GOE). This rapid transition may be related an atmospheric instability caused by formation of ozone layer. Previous works were all based on 1D photochemical models. Here, we revisit GOE with 3D photochemical–climate model in...