Plasticized single conductung polyelectrolytes based on poly (AMPS)

Poly(2-acrylamido-2-methyl-propane-1-sulphonic acid), poly(AMPS), has been ion exchanged with lithium and sodium to form alkali metal ion conducting polyelectrolytes. In the pure form these materials are rigid and would thus show limited conductivity. However addition of water or dimethylsulphoxide, as plasticizers, increases the conductivity by several orders or magnitude. The thermal analysis and NMR relaxation studies of these systems suggest that the increase in conductivity is as a direct result of increased ion mobility although the FTIR evidence still suggests significant ion association consistent with weak electrolytes. Although the T_g's of the sodium form of the polymer were higher, this system displayed higher conductivities than lithium which can be explained by a greater degree of ion dissociation and hence a larger number of charge carriers in the case of sodium poly(AMPS).     

Group transfer polymerisation in hydrophobic ionic liquids

For the first time, group transfer polymerisation of methyl methacrylate (MMA) has been successfully carried out at ambient temperatures in an ionic liquid to produce living polymers of improved polydispersity.     

Ab initio nonadiabatic molecular dynamics of the ultrafast electron injection across the alizarin-TiO2 interface

The observed 6-fs photoinduced electron transfer (ET) from the alizarin chromophore into the TiO2 surface is investigated by ab initio nonadiabatic (NA) molecular dynamics in real time and at the atomistic level of detail. The system derives from the dye-sensitized semiconductor Gr?tzel cell and addresses the problems of an organic/inorganic interface that are commonly encountered in photovoltaics, photochemistry, and molecular electronics. In contrast to the typical Gr?tzel cell systems, where molecular donors are in resonance with a high density of semiconductor acceptor states, TiO2 sensitized with alizarin presents a novel case in which the molecular photoexcited state is at the edge of the conduction band (CB). The high level ab initio analysis of the optical absorption spectrum supports this observation. Thermal fluctuations of atomic coordinates are particularly important both in generating a nonuniform distribution of photoexcited states and in driving the ET process. The NA simulation resolves the controversy regarding the origin of the ultrafast ET by showing that although ultrafast transfer is possible with the NA mechanism, it proceeds mostly adiabatically in the alizarin-TiO2 system. The simulation indicates that the electron is injected into a localized surface state within 8 fs and spreads into the bulk on a 100-fs or longer time scale. The molecular architecture seen in the alizarin-TiO2 system permits efficient electron injection into the edge of the CB by an adiabatic mechanism without the energy loss associated with injection high into the CB by a NA process.     

Match statistics for sequence-based alleles in profiles from forensic PCR-mps kits

The first autosomal sequence-based allele (aka SNP-STR haplotype) frequency database for forensic massively parallel sequencing (MPS) has been published, thereby removing one of the remaining barriers to implementing MPS in casework. The database was developed using a specific set of flank trim sites. If different trim sites or different kits with different primers are used for casework, then SNP-STR haplotypes may be detected that do not have frequencies in the database. We describe a procedure to address calculation of match probabilities when casework samples are generated using an MPS kit with different trim sites than those present in the relevant population frequency database. The procedure provides a framework for comparison of any MPS kit or database combination while also accommodating comparison of MPS and CE profiles.     

Transport in ceria electrolytes modified with sintering aids: effects on oxygen reduction kinetics

Small (2 mol%) cobalt oxide additions to ceria-gadolinia (CGO) materials considerably improve sinterability, making it possible to obtain ceramics with 95–99% density and sub-micrometre grain sizes at 1,170–1,370 K. The addition of Co causes a significant shift of the electrolytic domain to lower pO₂. This modification to the minor electronic conductivity of the electrolyte material has influence on the cathodic oxygen reduction reaction. The impedance technique is shown to provide information not only about polarisation resistance, but also about the active electrode area from analysis of the current constriction resistance. It is demonstrated that this current constriction resistance can be related to the minor electronic contributions to total conductivity in these materials. A simple imbedded grid approach gives control of the contact area allowing the properties of the electrolyte materials to be studied. A much lower polarisation resistance for the Co-containing CGO electrolyte is observed, which can be clearly attributed to an increased three-phase reaction area in the Co-containing material, as a consequence of elevated p-type conductivity.     

Proteomic analysis of the Arabidopsis thaliana cell wall

With the completion of the Arabidopsis genome, many hypothetical proteins have been predicted without any information on their expression, subcellular localisation and function. We have performed proteomic analysis of proteins sequentially extracted from enriched Arabidopsis cell wall fractions and separated by two-dimensional gel electrophoresis (2-DE). The proteins were identified by peptide mass fingerprinting using matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry and genomic database searches. This is part of a targeted exercise to establish the entire Arabidopsis secretome database. We report evidence for new proteins of unknown function whose existence had been predicted from genomic sequences and, furthermore, localise them to the cell wall. In addition, we observed an unexpected presence in the cell wall preparations of proteins whose known biochemical activity has never been associated with this compartment hitherto. We discuss the implications of these findings and present results suggesting a possible involvement of cell wall kinases in plant responses to pathogen attack.     

A homologous series of regioselectively tetradeprotonated group 8 metallocenes: new inverse crown ring compounds synthesized via a mixed sodium-magnesium tris(diisopropylamide) synergic base

Subjecting ferrocene, ruthenocene, or osmocene to the synergic amide base sodium-magnesium tris(diisopropylamido) affords a unique homologous series of metallocene derivatives of general formula [(M(C(5)H(3))(2))Na(4)Mg(4)(i-Pr(2)N)(8)] (where M = Fe (1), Ru (2), or Os (3)). X-ray crystallographic studies of 1-3 reveal a common molecular "inverse crown" structure comprising a 16-membered [(NaNMgN)(4)](4+) "host" ring and a metallocenetetraide [M(C(5)H(3))(2)](4-) "guest" core, the cleaved protons of which are lost selectively from the 1, 1', 3, and 3'-positions. Variable-temperature NMR spectroscopic studies indicate that 1, 2, and 3 each exist as two distinct interconverting conformers in arene solution, the rates of exchange of which have been calculated using coalescence and EXSY NMR measurements.