Redox-active amino acids were synthesized for incorporation into peptide assemblies to study photoinitiated electron or energy transfer. 4′-Methyl-2,2′-bipyridine-4-carboxylic acid was obtained in ...72% yield by consecutive SeO
2 and Ag
2O oxidation without isolation of intermediates. The side chain ε-amino group of Boc-
l-lysine methyl ester or γ-carboxyl group of Boc-
l-glutamic acid α-methyl ester was coupled to a redox moiety (transition-metal chromophore, electron donor, electron acceptor, metal ligand, or triplet-energy transmitter) using 4-(dimethylamino)pyridine, (1-benzotriazoleoxy)tris(dimethylamino)phosphonium hexafluorophosphate,
N-methylmorpholine, and 1-hydroxybenzotriazole. Use of one equivalent of 4-(dimethylamino)pyridine provided the amide coupling product in 80–97% isolated yield. Selective hydrolysis of the methyl esters with lithium hydroxide provided the redox Boc-amino acids in 70–98% yield. These redox modules are suitable for solid-phase assembly of light-harvesting peptides, as illustrated by the synthesis of the partially α-helical 11-residue redox triad that contains a phenothiazine electron donor, a ruthenium(II)tris(bipyridine) chromophore, and an anthraquinone electron acceptor. Upon laser excitation at 420 nm, the peptide triad underwent photoinduced electron transfer to create a charge-separated state with a lifetime of 53 ns and decayed with a first-order rate constant of 1.9 × 10
8 s
−1.
Redox-active modules were synthesized and assembled by solid-phase synthesis into a partially α-helical 11-residue light-harvesting peptide.
The Sentinel-3 Mission: Overview and status Donlon, C.; Berruti, B.; Mecklenberg, S. ...
2012 IEEE International Geoscience and Remote Sensing Symposium,
2012-July
Conference Proceeding
The series of Global Monitoring for Environment and Security (GMES) Sentinel satellites will continue and extend the European heritage of ENVISAT to provide data to numerous user communities. ...Sentinel-3 is being developed to support GMES Ocean and global Land monitoring services. Two Sentinel-3 satellites are in development with a first launch in 2014 and the second satellite expected approximately 18 months after the first. This paper provides an overview of the Sentinel-3 Mission.
Aerographite (AG) is a mechanically robust, lightweight synthetic cellular material, which consists of a 3D interconnected network of tubular carbon 1. The presence of open channels in AG aids to ...infiltrate them with polymer matrices, thereby yielding an electrical conducting and lightweight composite. Aerographite produced with densities in the range of 7–15 mg/cm3 was infiltrated with a low viscous epoxy resin by means of vacuum infiltration technique. Detailed morphological and structural investigations on synthesized AG and AG/epoxy composite were performed by scanning electron microscopic techniques. Our present study investigates the fracture and failure of AG/epoxy composites and its energy absorption capacity under compression. The composites displayed an extended plateau region when uni-axially compressed, which led to an increase in energy absorption of ~133% per unit volume for 1.5 wt% of AG, when compared to pure epoxy. Preliminary results on fracture toughness showed an enhancement of ~19% in KIC for AG/epoxy composites with 0.45 wt% of AG. Furthermore, our observations of fractured surfaces under scanning electron microscope gives evidence of pull-out of arms of AG tetrapod, interface and inter-graphite failure as the dominating mechanism for the toughness improvement in these composites. These observations were consistent with the results obtained from photoelasticity experiments on a thin film AG/epoxy model composite.
The adoption of Article V, Section 1 of the Montana Constitution, on November 6, 1906 initiated the process of initiative and referendum in Montana and it has been heavily used ever since. An ...initiative is a proposal by petition to enact a new law by a vote of the people on any matter except the appropriation of money, or local or special laws. If the petitions are signed by the required number of electors, the proposed initiative must be submitted to the qualified electors. A referendum is a proposal by which the people, by their majority vote, can approve or reject a previously enacted statute, except an appropriation of money. A referendum may be originated by the legislature that enacted the statute or by the people. The Montana Secretary of State Elections Bureau and the Montana Legislative Library are invaluable sources of information for initiative and referendum in Montana and have subject lists of all these measures attempted in the state.
Law libraries that serve the public have diverse clientele, types of reference and research requirements, and opportunities for contact that firm and academic law libraries seldom experience. This ...article explores these opportunities, which the authors take advantage of for providing a "teachable moment." opportunity to teach something. The specific subjects are diverse: the legislative process, summary dissolution, arbitration rules, or how to use a keyboard's mouse. Our constant goal is to teach or show that libraries and librarians are still an integral part of today's commercial and legal arenas, and to demonstrate that a government agency can actually be a beneficial tax-supported institution.
