Synthesis and biological action of novel 4-position-modified derivatives of D-myo-inositol 1,4,5-trisphosphate

The design of a range of 4-position-modified D-myo-inositol 1,4,5-trisphosphate derivatives is described. The enantioselective synthesis of these compounds is reported, along with initial biological analysis, which indicates that these compounds do not act as D-myo-inositol 1,4,5-trisphosphate receptor agonists or antagonists.     

Structurally-defined direct C-magnesiation and C-zincation of N-heterocyclic aromatic compounds using alkali-metal-mediated metallation

Demonstrating direct synergic "low polarity metallation", 1-methylindole is C-magnesiated by (TMEDA)(2).Na(2)MgBu(4) and C-zincated by (TMEDA).Na((t)Bu)(TMP)Zn((t)Bu), and 1-methylpyrrole is C-zincated by the same reagent, with all three metal products successfully crystallographically characterised.     

Effects of thermal impact on a thin spherical cap

Because of the importance of thin shells as structural elements in all aircraft and missile vehicles, the response of the shell to transient thermal loads is of extreme interest. At very high heating rates, as can be produced by the absorption of intense radiation energy, dynamic mechanical response of the structure may be produced. This paper describes a brief exploratory investigation of the effects of short-duration, high-intensity thermal radiation exposure of a thin-shell structure. Exposure of a spherical cap in a arc-image furnance failed to produce buckling under the test conditions. Rapid thermal rupture, however, did result in interesting failure surfaces.     

An Oxygen‐Tolerant PET‐RAFT Polymerization for Screening Structure–Activity Relationships

The complexity of polymer–protein interactions makes rational design of the best polymer architecture for any given biointerface extremely challenging, and the high throughput synthesis and screening of polymers has emerged as an attractive alternative. A porphyrin‐catalysed photoinduced electron/energy transfer–reversible addition‐fragmentation chain‐transfer (PET‐RAFT) polymerisation was adapted to enable high throughput synthesis of complex polymer architectures in dimethyl sulfoxide (DMSO) on low‐volume well plates in the presence of air. The polymerisation system shows remarkable oxygen tolerance, and excellent control of functional 3‐ and 4‐arm star polymers. We then apply this method to investigate the effect of polymer structure on protein binding, in this case to the lectin concanavalin A (ConA). Such an approach could be applied to screen the structure–activity relationships for any number of polymer–protein interactions.     

Elementary steps and mechanism of electrodeposition of Al from complex hydride ions in tetrahydrofuran baths

Electrocrystallization of Al cannot be achieved from aqueous media, but is possible from low melting-point organic salts, and from aromatic and etheric solutions. In the present paper studies are reported on the kinetics and mechanisms of electrodeposition of Al from plating baths of varying ratios of AlCl₃ and LiAlH₄ dissolved in tetrahydrofuran (THF). A complementary paper, which follows, deals with the topic of nucleation and growth processes involved in Al phase electrocrystallization and provides experimental results on that process. Steady-state cathodic and anodic Tafel polarization relations are determined, complemented by ac impedance studies. Back-reaction corrected Tafel plots enable anodic and cathodic transfer coefficients (α) to be evaluated together with corresponding stoichiometric numbers (ν). Critical evaluation both of the present α and ν results, and previous α values in the literature, enables a mechanism of elementary steps in Al deposition from the hydrido-chloride baths to be proposed.     

Profile evolution of edge parameters during L/H and H/L mode transitions on compass-D

On COMPASS-D the profile evolution of electron density, electron temperature, perpendicular electric field, poloidal impurity velocity, and neutral density at the outboard mid-plane has been investigated during ohmic single null diverted (SND) discharges undergoing an L/H, H/L, and another L/H transition. This was achieved using a novel combined diagnostic consisting of thermal helium beam and Doppler spectrometry, sharing the same lines of sight. To generate the transitions first an ELM-free H-mode phase was produced by terminating the gas fuelling. Within this H-mode a stepped gas puff was applied triggering an intermediate L-mode phase followed by a second ELM-free phase. It was found that on COMPASS-D the L/H transition is not preceded by a change in velocity or electric field shear. The maximum electric field shear of ∇ ▽E _ψ ≈2×10³kV/m² develops after the L/H transition around the 95% flux surface. Although the neutral density at the separatrix is of the ordern _D ≈ 10¹⁷m⁻³ no indication of a local influence could be concluded. However, a correlation between the decay of the shear and the gas puff was observed. Presented at the Workshop on Role of Electric Fields in Plasma Confinement and Exhaust, Budapest, 18–19 June 2000. This work was jointly funded by the UK Department of Trade and Industry and EURATOM. The author H. Meyer is funded by a Marie Curie Research Training Grant.