CHEMILUMINESCENCE FROM THE REDUCTION OF AROMATIC AMINE CATIONS AND RUTHENIUM(III) CHELATES*,‡

Abstract— –Chemiluminescence is reported from two types of reactions; those involving the reduction of amine cations yield fluorescence amines: RN H₂^+m+ reductant → RN H₂+hv and those involving reduction of transition metal chelates where the reduced form of the chelate is fluorescent: ML_x⁺⁽ⁿ⁺¹⁾+ reductant →ML_x⁺ⁿ+hv The results reported here are for reduction of the cation radical of 1,6-diaminopyrene and ruthenium (III) chelates where chelate ligands are substituted 1,10-phenanthrolines or 2,2'-bipyridine. Reducing agents for 1,6-diaminopyrene were hydrazine or the naphthalene radical anion; for the ruthenium chelates either hydroxyl ion or hydrazine in acid solution. A detailed study is reported for the kinetics of the ruthenium (III)-hydrazine reaction, using a computer kinetic modeling program. A quantitative fit of the experimental data to computer-generated curves can be accomplished at low hydrazine concentrations. At higher hydrazine concentrations the correct qualitative shapes of curves can be generated but the quantitative fit is not exact.     

The effect of olefinic terminal chains on the mesomorphic properties of 4,4′-disubstituted diphenyldiacetylenes

New diphenyldiacetylenes of the type with A, B = H and/or F; m = 0, 1; n = 1–4; and X = C _n H_2n+1, F, CF₃ or CN were synthesized and their mesomorphic properties determined by hot stage polarizing microscopy and DSC. When m = 0, all of these compounds showed only a nematic phase except when X = CF₃ when both nematic and smectic A phases were seen. Both clearing and melting temperatures were higher than those reported for substitution with the corresponding alkyl chains but the much larger increase in clearing temperatures produced considerably wider nematic phases. Eutectic mixtures of a few of these olefins yielded nematic materials also having much wider temperature ranges and higher clearing temperatures than the eutectic mixtures of the alkyl compounds, while retaining their high birefringence and low viscosities. Such materials are of interest for beam-steering devices. Four of the diacetylenes with m = 1 (A, B = H) were also prepared (X = C₆H₁₃, F, n= 2, 3). When X was C₆H₁₃ (n=2), the nematic range was smaller in the 2- than in the 1-olefin but wider than in the alkyl series. When X=F, either no nematic phase or a monotropic one was observed, whereas the 1-olefins gave a much wider nematic phase. Both transition temperatures were lower than those for the corresponding 1-olefin and alkyl analogues. The compound with X=C₆H₁₃ and n=2 had a melting temperature below room temperature.     

BUYING ECOLOGICAL SERVICES: FRAGMENTED RESERVES,CORE AND PERIPHERY NATIONAL PARK STRUCTURE,AND THE AGRICULTURAL EXTENSIFICATION DEBATE

Abstract Growing demand for cropland products has placed intense pressure on the ability of land resources to support nature, straining public budgets to purchase environmental goods. Fixing overall agricultural output, two environmental policy options are whether to (i) promote more agricultural extensification and nature‐friendly farming practices or (ii) produce intensively on some land and leave the rest wild. Microeconomic models of the topic have not accounted for widely recognized spatial externalities regarding fragmented reserves. This article does so, using Wirtinger's inequality to also identify a third policy possibility. This is that ecological services can follow a smoothly varying spatial path chararacterized by harmonic functions. We use the results to rationalize the core and periphery national park structure put in place around the world, that is, versions of our third policy possibility have been implemented.     

Energetics,electronic structures and geometries of naphthalene,quinoline and isoquinoline analogues of 1,2-didehydrobenzene

B3LYP/cc-pVTZ electronic structure calculations employed in conjunction with additive corrections derived from experimental data for 1,2-didehydrobenzene predict the standard enthalpies of formation of 1,2- and 2,3-didehydronaphthalenes to be equal to 121.0 and 123.7 kcal mol^?1, respectively. The corresponding singlet-triplet splittings amount to 40.1 and 35.4 kcal mol^?1. The positional dependence of both of these quantities is preserved in those didehydroquinolines and didehydroisoquinolines in which the didehydrogenation sites are separated by at least one carbon from the heteroatoms. The effect of the adjacent heteroatoms on the singlet-triplet splittings is significantly more pronounced than that on the standard enthalpies of formation. Test G3 calculations on 2,3-didehydronaphthalene confirm the reliability of the additive correction scheme in the prediction of properties of annelated analogues of 1,2-didehvdrobenzene. Such a scheme opens an avenue to facile electronic structure calculations on didehydrogenation reactions of polycondensed heterocyclic compounds with six-membered rings.     

MULTISPECIES MODELING FOR ADAPTIVE MANAGEMENT OF HORSESHOE CRABS AND RED KNOTS IN THE DELAWARE BAY

Abstract Adaptive management requires that predictive models be explicit and transparent to improve decisions by comparing management actions, directing further research and monitoring, and facilitating learning. The rufa subspecies of red knots (Calidris canutus rufa), which has recently exhibited steep population declines, relies on horseshoe crab (Limulus polyphemus) eggs as their primary food source during stopover in Delaware Bay during spring migration. We present a model with two different parameterizations for use in the adaptive management of horseshoe crab harvests in the Delaware Bay that links red knot mass gain, annual survival, and fecundity to horseshoe crab dynamics. The models reflect prevailing hypotheses regarding ecological links between these two species. When reported crab harvest from 1998 to 2008 was applied, projections corresponded to the observed red knot population abundances depending on strengths of the demographic relationship between these species. We compared different simulated horseshoe crab harvest strategies to evaluate whether, given this model, horseshoe crab harvest management can affect red knot conservation and found that restricting harvest can benefit red knot populations. Our model is the first to explicitly and quantitatively link these two species and will be used within an adaptive management framework to manage the Delaware Bay system and learn more about the specific nature of the linkage between the two species.