The electron field-emission properties of hydrogenated amorphous carbon and nitrogenated tetrahedral amorphous carbon thin films are examined by measuring the field-emission current as a function of the applied macroscopic electric field. The experimental results indicate the existence of an optimum film thickness for low-threshold electron field emission. The predictions of various emission models are compared to the experimental results.

Lygus species of plant-feeding insects have emerged as economically important pests of cotton in the United States. These species are not controlled by commercial Bacillus thuringiensis (Bt) cotton varieties resulting in economic losses and increased application of insecticide. Previously, a Bt crystal protein (Cry51Aa2) was reported with insecticidal activity against Lygus spp. However, transgenic cotton plants expressing this protein did not exhibit effective protection from Lygus feeding damage. Here we employ various optimization strategies, informed in part by protein crystallography and modelling, to identify limited amino-acid substitutions in Cry51Aa2 that increase insecticidal activity towards Lygus spp. by >200-fold. Transgenic cotton expressing the variant protein, Cry51Aa2.834_16, reduce populations of Lygus spp. up to 30-fold in whole-plant caged field trials. One transgenic event, designated MON88702, has been selected for further development of cotton varieties that could potentially reduce or eliminate insecticide application for control of Lygus and the associated environmental impacts.

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CYP84 is a recently identified family of cytochrome P450-dependent mono-oxygenases defined by a putative ferulate-5-hydroxylase (F5H) from Arabidopsis. Until recently F5H has been thought to catalyze the hydroxylation of ferulate to 5-OH ferulate en route to sinapic acid. Sinapine, a sinapate-derived ester in the seeds, is antinutritional and a target for elimination in canola meal. We have isolated three F5H-like genes (BNF5H1-3) from a cultivated Brassica napus, whose amphidiploid progenitor is considered to have arisen from a fusion of the diploids Brassica rapa and Brassica oleracea. Two cultivated varieties of the diploids were also found to contain BNF5H3 and additionally either BNF5H1 or BNF5H2, respectively. Whereas all three are Ͼ90% identical in their coding sequence, BNF5H1 and BNF5H2 are closer to each other than to BNF5H3. This and additional data suggest that the two groups of genes have diverged in an ancestor of the diploids. B. napus showed maximal F5H expression in the stems, least in the seeds, and subtle differences among the expression profiles of the three genes elsewhere. Transgenic B. napus with cauliflower mosaic virus 35S-antisense BNF5H contained up to 40% less sinapine, from 9.0 Ϯ 0.3 mg in the controls to 5.3 Ϯ 0.3 mg g Ϫ1 seed. F5H from Arabidopsis and a similar enzyme from sweetgum (Liquidamber styraciflua) has recently been shown to have coniferaldehyde hydroxylase activity instead of F5H activity. Thus the supply of 5-OH coniferaldehyde or 5-OH ferulate has a bearing on sinapine accumulation in canola seeds.Secondary metabolism is indeed essential to the form and function of plants and also to the survival of these sessile members in their diverse and dynamic ecosystems. The products range from relatively simple phenolic esters to the complex, heterogeneous polymers of lignin. These metabolites have a wide range of often disparate functions ranging from providing mechanical strength to pest deterrence to facilitation of symbiosis (Strack, 1997). The general phenylpropanoid pathway is central to secondary metabolism from various perspectives (Dooner et al

A new bis(β-diketonate), 1,3-bis(4,4,4-trifluoro-1,3-dioxobutyl)phenyl (BTP), which contains a trifluorinated alkyl group, has been prepared for the synthesis of two series of dinuclear lanthanide complexes with the general formula Ln2(BTP)3L2 [Ln(3+) = Eu(3+), L = DME(1), bpy(2), and phen(3); Ln(3+) = Sm(3+), L = DME(4), bpy(5), and phen(6); DME = ethylene glycol dimethyl ether, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline]. The crystal structure of the free ligand has been determined and shows a twisted arrangement of the two binding sites around the 1,3-phenylene spacer. X-ray crystallographic analysis reveals that complexes 1, 2, 4, and 5 are triple-stranded dinuclear structures formed by three bis-bidentate ligands with two lanthanide ions. The room-temperature photoluminescence (PL) spectra of complexes 1-6 show that this bis-β-diketonate can effectively sensitize rare earths (Sm(3+) and Eu(3+)) and produce characteristic emissions of the corresponding Eu(3+) and Sm(3+) ions. In addition, two bidentate nitrogen ancillary ligands, 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), have been employed to enhance the luminescence quantum yields and lifetimes of both series of Eu(3+) and Sm(3+) complexes.