Light-induced charge separation in ruthenium based triads - New variations on an old theme

Success with artificial photosynthesis requires control of the photoinduced electron transfer reactions leading to charge-separated states. In this review, some new ideas to optimize such charge-separated states in ruthenium(II) polypyridyl based three-component systems with respect to: (1) long lifetimes and (2) ability to store sufficient energy for catalytic water splitting, are presented. To form long-lived charge-separated states, a manganese complex as electron donor and potential catalyst for water oxidation has been used. The recombination reaction is unusually slow because it occurs deep down in the Marcus normal region as a consequence of the large bond reorganization following the manganese oxidation. For the creation of high energy charge-separated states, a strategy using bichromophoric systems is presented. By consecutive excitations of the two chromophores, the formation of charge-separated states that lie higher in energy than either of the two excited states could in theory be achieved, the first results of which will be discussed in this review.     

Temperature adaptation by the myotomal muscle of fish

Fish living within a fluctuating thermal environment (eurythermal) are able to adapt their contractile proteins to suit a particular temperature. In goldfish, this adaptive capability has limits, which correspond to their preferred temperature (10°C - 30°C), but fish are able to tolerate extremes (0°C - 40°C). Adaptations in catalytic efficiency and thermostability of the myofibrillar ATPase are controlled by the regulatory proteins. Fish living in a limited temperature range have evolved contractile proteins designed specifically to function at that temperature. A fish living at a constant temperature (stenothermal) was also examined to see if it could adapt its contractile apparatus. Myofibrillar ATPase from trout kept at 5°C and at 20°C showved no differences in either specific activity or thermostability. Furthermore, when placed in a temperature gradient trout have been reported to select the same temperature, regardless of thermal history. It is unknown whether trout, as it is a primitive fish, has never had the ability to adapt its contractile apparatus, or, as it lives in a relatively unchanging temperature it has never needed to.     

Iron based oxypnictides: Structure and properties

Metals, alloys and metal oxides have been investigated over several decades for their interesting electronic properties including superconductivity. However the pnictides (multinary compounds containing at least one pnictogen) have not been so popular for their superconducting properties. That has changed recently (2008) after the discovery of superconductivity at 26 K in fluoride-doped LaO_0.9F_0.1FeAs by Kamihara et al. [1] which has created a huge excitement in the field of superconductivity and pnictides. Since then a large number of pnictogen based superconductors were discovered. This article summarizes the structure and properties of the parent compounds, LnOFePn (Ln = La, Ce and Pr; Pn = P and As). Effect of Fe-Pn hybridization on structural distortion, electronic and magnetic properties of LnOFePn is examined.     

Peptide Chain Initiation in Bacteria,Mitochondria and Chloroplasts

Abstract

Ribosomes prepared from the bacterium Bacillus subtilis, from mitochondria of Neurospora crassa and from chloroplasts of Euglena gracilis carry out the ApUpG-dependent reactions for peptide chain initiation demonstrated for Escherichia coli ribosomes. Initiation factors functionally similar to those from E. coli appear to be present on the above reported ribosomal preparations. The activity of ribosomes washed with high concentrations of ammonium chloride may be restored by adding initiation factors prepared from E. coli.     

Mitochondrial morphogenesis: Fusion factor for fly fertility

The Drosophila Fzo protein is required for mitochondrial fusion during a key step in sperm formation. This novel, membrane-bound GTPase defines a family of proteins that may mediate mitochondrial fusion in a variety of eukaryotic cells.