Reaction of naphthalene‐2,3‐dicarbaldehyde with cyanide; A unique oxidative condensation product

Naphthalene‐2,3‐dicarbaldehyde (NDA), a reagent used for the fluorescent detection of amino acids in the presence of cyanide, self‐condenses in the presence of cyanide ion and methanol at room temperature to yield a unique crystalline product 2, 15‐hydroxybenzo[g]benzo[6,7]isochromeno[4,3‐c]isochromen‐7(15H)‐one. The product is proposed to result from facile air oxidation of NDA to a methyl ester in combination with benzoin condensation. Product 2 does not to form in the absence of air. The gHMBC spectrum of 2 distinguishes it from a possible alternative isomeric condensation product.     

Periodic Fermentor Yield and Enhanced Product Enrichment from Autonomous Oscillations

Four decades of work have clearly established the existence of autonomous oscillations in budding yeast culture across a range of operational parameters and in a few strains. Autonomous oscillations impact substrate conversion to biomass and products. Relatively little work has been done to quantify yield in this case. We have analyzed the yield of autonomously oscillating systems, grown under different conditions, and demonstrate that it too oscillates. Using experimental data and mathematical models of yeast growth and division, we demonstrate strategies to increase the efficient recovery of products. The analysis makes advantage of the population structure and synchrony of the system and our ability to target production within the cell cycle. While oscillatory phenomena in culture have generally been regarded with trepidation in the engineering art of bioprocess control, our results provide further evidence that autonomously oscillating systems can be a powerful tool, rather than an obstruction.     

Tariff concessions in production sourcing

In this paper, we study a multi-stage production sourcing problem where tariff concessions can be exploited at the firm level using free trade agreements between countries. To solve the problem, an algorithm which embeds a very large-scale neighborhood (VSLN) search into a simulated annealing framework is developed. A numerical study is conducted to verify the effectiveness of the solution approach.     

The growth rate of the harmonious chromatic number

In this paper we investigate the growth rate of the harmonious chromatic number of a family of regular graphs, as a function of the number of vertices, when the valency or the diameter is fixed. We also look at families of graphs where the harmonious coloring is minimal.     

Synthesis and characterization of high molecular weight hexafluoroisopropylidene‐containing polybenzimidazole for high‐temperature polymer electrolyte membrane fuel cells

A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F‐PBI) was synthesized from 3,3′‐diaminobenzidine (TAB) and 2,2‐bis(4‐carboxyphenyl) hexafluoropropane (6F‐diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F‐PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064–4073, 2009     

Carbazolylmethylphosphonate compounds – Synthesis,coordination and fluorescence in solution and cells

The compounds diethyl-N-carbazolylmethylphosphonate 1 and diethyl-2-oxymethylphosphonate carbazole 2 have been synthesised and characterized by a range of techniques including NMR, absorption and emission spectroscopy, infrared, and mass spectroscopy. Compound 1 forms a 2:1 complex 3 with calcium nitrate and the single crystal X-ray diffraction structure of 3 is described. Titrations of 1 with Zn²⁺ and Ca²⁺ in ethanol reveal that the intrinsic fluorescence is only slightly perturbed in the presence of these metal ions in micromolar ethanol solutions. Compounds 1 and 2 are readily taken up and visualized in L929 fibrosarcoma and DRG (Dorsal root ganglia) cell lines.     

Synthesis and characterisation of trinuclear metal complexes derived from carboxymethyl-substituted sarcophagine macrobicyclic cage amines

The synthesis and single-crystal x-ray structure determination of two new trinuclear metal complexes is detailed. In these we utilise the appended iminodiacetate substituents, in [Co(CH₃)NH(CH₂CO₂H)₂sar]³⁺, to act as a focus for coordination of other metal ions. Thus, we have made complexes of Cu and Ni utilising the basic carbonates of these metals and [Co(CH₃){N(CH₂CO₂H)₂}sar]³⁺ (CoL2) which gave rise to ((CoL2–2H⁺)₂M), M = Cu and Ni. The electrochemical study of the latter was inconclusive and provides the impetus for further study.