1. Photoxidation in leaves is measured by exposing them to light in an atmosphere free from carbon dioxide but containing varied percentages of oxygen. 2. Photoxidation is observed in living leaves as well as in dead ones and in plant juices. Its rate is only slightly enhanced by feeding the leaves with sugar, but the respiration (autoxidation) becomes considerably enlarged during the exposure ...

The heterogeneous chemical kinetics of N2O5 on CaCO3 and other atmospheric mineral dust surrogates F. Karagulian, C. Santschi, and M. J. Rossi Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Pollution Atmosphérique et Sol (EPFL, LPAS), Bâtiment CH H5, Station 6, CH-1015 Lausanne, Switzerland Received: 7 September 2005 – Accepted: 12 September 2005 – Published: 24 October 2005 Correspon...

Several liquid sample injection methods have been developed to satisfy the requirements for serial femtosecond X-ray nanocrystallography, which enables radiation-damage-free determination of molecular structure at room temperature. Time-resolved nanocrystallography would combine structure analysis with chemical kinetics by determining the structures of the transient states and chemical kinetic ...

This article provides an introduction to a computer tutorial on transient state kinetics. The tutorial uses our Macintosh version of the computer program, KINSIM, that calculates the time course of reactions. KINSIM is also available for other popular computers. This program allows even those investigators not mathematically inclined to evaluate the rate constants for the transitions between th...

We use the statistics of photon emission from single molecules to probe the ultrafast dynamics of an unfolded protein via Förster resonance energy transfer. Global reconfiguration of the chain occurs on a time scale of approximately equal to 50 ns and slows down concomitant with chain collapse under folding conditions. These diffusive dynamics provide a missing link between the phenomenological...

We show that steady-state catalytic conversion in nanoporous materials can occur in a quasi-counter-diffusion mode with the reactant (product) concentration strongly decaying (growing) into the pore, but also with oscillations in the total concentration. These oscillations reflect the response of the fluid to the transition from an extended to a confined environment near the pore opening. We fo...

A comprehensive one-dimensional photochemical model extending from the middle atmosphere (50 km) to the exobase (432 km) has been used to study the escape of hydrogen and deuterium from the Earth's atmosphere. The model incorporates recent advances in chemical kinetics as well as atmospheric observations by satellites, especially the Atmosphere Explorer C satellite. The results suggest: (1) ...

It is felt very essential to develop a knowledge base on dye chemistry and effects of dyeing process variables as well as rate of dyeing and chemical kinetics of dyeing for different natural dyes and fibres combinations to manipulate the processes of natural dyeing efficiently in order to get maximum color yield in economical way. A review on the effects of dye extraction medium, optimum concen...

Based on the facts of chemistry and current storage conditions, the Shroud of Turin is in no danger of autocatalytic decomposition. Autocatalytic chemical reactions are those in which the rate increases as the materials react. The most important single factor in predicting effects is the temperature. When the temperature changes, the rate changes. The only severe heating episode the Shroud has ...

The enzyme-catalyzed conversion of a substrate into a product is a common reaction motif in cellular chemical systems. In the three reactions that comprise this process, the intermediate enzyme-substrate complex is usually much more likely to decay into its original constituents than to produce a product molecule. This condition makes the reaction set mathematically "stiff." We show here how th...