A method for accelerating the discovery of ionic luminophores using combinatorial techniques is reported. The photophysical properties of the resulting transition-metal-based chromophores were ...compared against a series of analogous, traditionally prepared species. The strong overlap between these two sets confirms the identity of the parallel synthesis products and supports the truthfulness of the combinatorial results. Further support for the combinatorial method comes from the adherence of these complexes to the energy gap law. The relationship between the structure of a complex and its photophysical properties was also considered, and static DFT calculations were used to assess whether it is feasible to predict the luminescent behavior of novel materials.
Human immunoglobulin transgenic mice provide a method of obtaining human monoclonal antibodies (Mabs) using conventional hybridoma technology. We describe a novel strain of human immunoglobulin ...transgenic mice and the use of this strain to generate multiple high-avidity human sequence IgG kappa Mabs directed against a human antigen. The light chain transgene is derived in part from a yeast artificial chromosome clone that includes nearly half of the germline human V kappa region. In addition, the heavy-chain transgene encodes both human mu and human gamma 1 constant regions, the latter of which is expressed via intratransgene class switching. We have used these animals to isolate human IgG kappa Mabs that are specific for the human T-cell marker CD4, have high binding avidities, and are immunosuppressive in vitro. The human Mab-secreting hybridomas display properties similar to those of wild-type mice including stability, growth, and secretion levels. Mabs with four distinct specificities were derived from a single transgenic mouse, consistent with an extensive diversity in the primary repertoire encoded by the transgenes.
We report on the spectroscopic, electrochemical, and electroluminescent properties of Ir(ppy)2(dtb-bpy)+(PF6)- (ppy: 2-phenylpyridine, dtb-bpy: 4,4‘-di-tert-butyl-2,2‘-dipyridyl). Single-layer ...devices were fabricated and found to emit yellow light with a brightness that exceeds 300 cd/m2 and a luminous power efficiency that exceeds 10 Lm/W at just 3 V. The PF6 - space charge was found to dominate the device characteristics.
The Large Magellanic Cloud, a satellite galaxy of the Milky Way, has been observed with the High Energy Stereoscopic System (H.E.S.S.) above an energy of 100 billion electron volts for a deep ...exposure of 210 hours. Three sources of different types were detected: the pulsar wind nebula of the most energetic pulsar known, N 157B; the radio-loud supernova remnant N 132D; and the largest nonthermal x-ray shell, the superbubble 30 Dor C. The unique object SN 1987A is, unexpectedly, not detected, which constrains the theoretical framework of particle acceleration in very young supernova remnants. These detections reveal the most energetic tip of a γ-ray source population in an external galaxy and provide via 30 Dor C the unambiguous detection of γ-ray emission from a superbubble.
For the first time, free base and
N
-methylated porphyrins have been utilized as bifunctional organocatalysts in Michael additions and it was found that distortion of the macrocycle is a vital ...prerequisite for their catalytic activity. Conformational design has been used to tailor the properties of nonplanar porphyrins with regards to availability of the N-H units for hydrogen bonding (distortion-dependent hydrogen bonding) and the basicity of the heterocyclic groups. NMR spectroscopic- and catalyst screening studies provided insight into the likely mode of catalyst action. This unprecedented use of free base and
N
-substituted porphyrins as organocatalysts opens a new functional role for porphyrins.
No metal needed: nonplanar free base porphyrins act as bifunctional organocatalysts revealing a new mode of action for porphyrins.
Metabolite Transfer Via Enzyme-Enzyme Complexes Srivastava, D. K.; Bernhard, Sidney A.
Science (American Association for the Advancement of Science),
11/1986, Letnik:
234, Številka:
4780
Journal Article
Recenzirano
The concentrations of enzyme sites in cells are usually higher than the concentrations of cognate intermediary metabolities. Therefore metabolic pathways or substantial segments of pathways may ...proceed by the direct transfer of metabolities from one enzyme site to the next by means of enzyme-enzyme complex formation. This mechanism of metabolite transfer differs from that usually assumed where dissociation and random diffusion of metabolite through the aqueous environment is responsible for the transfer to the next enzyme site. Since the direct transfer mechanism does not involve the aqueous environment, the energetics of metabolite interconversion can differ from expectations based on aqueous solution data. Evidence is summarized suggesting that metabolite is transformed and transferred with equal facility everywhere in the direct transfer pathway.
Transition metal complexes have emerged as promising candidates for applications in solid-state electroluminescent devices. These materials serve as multifunctional chromophores, into which electrons ...and holes can be injected, migrate and recombine to produce light emission. Their device characteristics are dominated by the presence of mobile ions that redistribute under an applied field and assist charge injection. As a result, an efficiency of 10 lm/W--among the highest efficiencies reported in a single layer electroluminescent device--was recently demonstrated. In this article we review the history of electroluminescence in transition metal complexes and discuss the issues that need to be addressed for these materials to succeed in display and lighting applications.
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