Process for the preparation of fluorine containing crosslinked elastomeric polytriazine and product so produced

Crosslinking elastomeric polytriazines are prepared by a 4 step procedure which consists of (1) forming a poly(imidoylamidine) by the reaction, under reflux conditions, of anhydrous ammonia with certain perfluorinated alkyl or alkylether dinitriles; (2) forming a linear polytriazine by cyclizing the imidoylamidine linkages by reaction with certain perfluorinated alkyl or alkylether acid anhydrides or halides; (3) extending the linear polytriazine chain by further refluxing in anhydrous ammonia; and (4) heating to cyclize the new imidoylamidine and thereby crosslink the polymer

Advanced supersonic technology fuel tank sealants

Status of the fuel tank simulation and YF-12A flight tests utilizing a fluorosilicone sealant is described. New elastomer sealant development is detailed, and comparisons of high and low temperature characteristics are made to baseline fluorosilicone sealants

Polyimide fiber-glass composite resists high temperatures

Composites synthesized from bismaleimide have superior strength and oxidation resistance at elevated temperatures when compared with similar composites prepared with epoxy or silicon polymers of similar cost. Polyimide synthesis technique and processing method yield essentially void-free fiber-glass reinforced composites

Fiber-modified polyurethane foam for ballistic protection

Closed-cell, semirigid, fiber-loaded, self-extinguishing polyurethane foam material fills voids around fuel cells in aircraft. Material prevents leakage of fuel and spreading of fire in case of ballistic incendiary impact. It also protects fuel cell in case of exterior fire

Conference on the Development of Fire-Resistant Aircraft Passenger Seats

Papers are presented dealing with the development of aircraft seats with the minimum fire risk. Criteria examined include: flame spread, heat release, and smoke and/or toxic fumes. Materials and performance specifications of all seat material options are provided

Electrons in the Earth's Outer Radiation Zone

Electrons in the earths outer radiation bel

Conjugatable water-soluble Pt(ii) and Pd(ii) porphyrin complexes: Novel nano- and molecular probes for optical oxygen tension measurement in tissue engineering

Measurement of oxygen tension in compressed collagen sheets was performed using matrix-embedded optical oxygen sensors based on platinum(II) and palladium(II) porphyrins supported on polyacrylamide nanoparticles. Bespoke, fully water-soluble, mono-functionalised Pt(II) and Pd(II) porphyrin complexes designed for conjugation under mild conditions were obtained using microwave-assisted metallation. The new sensors display a linear response (1/τ vs. O₂) to varying oxygen tension over a biologically relevant range (7.0 × 10⁻⁴ to 2.7 × 10⁻¹ mM) in aqueous solutions; a behaviour that is maintained following conjugation to polyacrylamide nanoparticles, and following embedding of the nanosensors in compressed collagen sheets, paving the way to innovative approaches for real-time resolution of oxygen gradients throughout 3D matrices useful for tissue regeneration

Orthogonally bifunctionalised polyacrylamide nanoparticles: a support for the assembly of multifunctional nanodevices

Polyacrylamide nanoparticles bearing two orthogonal reactive functionalities were prepared by reverse microemulsion polymerisation. Water-soluble photosensitisers and peptide or carbohydrate moieties were sequentially attached to the new nanospecies by orthogonal conjugations based on copper- catalysed azide-alkyne cycloaddition and isothiocyanate chemistry

Gated rotation mechanism of site-specific recombination by ϕC31 integrase

Integrases, such as that of the Streptomyces temperate bacteriophage ϕC31, promote site-specific recombination between DNA sequences in the bacteriophage and bacterial genomes to integrate or excise the phage DNA. ϕC31 integrase belongs to the serine recombinase family, a large group of structurally related enzymes with diverse biological functions. It has been proposed that serine integrases use a “subunit rotation” mechanism to exchange DNA strands after double-strand DNA cleavage at the two recombining att sites, and that many rounds of subunit rotation can occur before the strands are religated. We have analyzed the mechanism of ϕC31 integrase-mediated recombination in a topologically constrained experimental system using hybrid “phes” recombination sites, each of which comprises a ϕC31 att site positioned adjacent to a regulatory sequence recognized by Tn3 resolvase. The topologies of reaction products from circular substrates containing two phes sites support a right-handed subunit rotation mechanism for catalysis of both integrative and excisive recombination. Strand exchange usually terminates after a single round of 180° rotation. However, multiple processive “360° rotation” rounds of strand exchange can be observed, if the recombining sites have nonidentical base pairs at their centers. We propose that a regulatory “gating” mechanism normally blocks multiple rounds of strand exchange and triggers product release after a single round

Charges and fields in a current-carrying wire

Charges and fields in a straight, infinite, cylindrical wire carrying a steady current are determined in the rest frames of ions and electrons, starting from the standard assumption that the net charge per unit length is zero in the lattice frame and taking into account a self-induced pinch effect. The analysis presented illustrates the mutual consistency of classical electromagnetism and Special Relativity. Some consequences of the assumption that the net charge per unit length is zero in the electrons frame are also briefly discussed