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51.
Douglas X. West Authrine C. Whyte Brenda L. Mokijewski Scott A. Frank 《Transition Metal Chemistry》1991,16(6):596-598
Summary Cobalt(II) and copper(II) complexes of the title ligand, TCEC, as well as a cobalt(II) complex ofN,N,N",N'-tetra (1-methyl-2-cyanoethyl)-1,4,8,11-tetraazacyclotetradecane, TMCEC, have been isolated and spectrally characterized. 相似文献
52.
Engelhardt FC Shi YJ Cowden CJ Conlon DA Pipik B Zhou G McNamara JM Dolling UH 《The Journal of organic chemistry》2006,71(2):480-491
[reaction: see text] A newly developed synthesis of a NO-releasing prodrug of rofecoxib is described. The highly productive process consists of five chemical steps and produces prodrug 1 in an overall 64% yield from commercially available 3-phenyl-2-propyn-1-ol (4). The synthesis is highlighted by the carbometalation reaction of propargyl alcohol 4 to generate the tetrasubstituted olefin core, sulfone acid 2. Additionally, two alternate end-game strategies to prepare NO-COXIB 1 from this intermediate were explored and developed: (1) a convergent synthesis where a bromonitrate side chain is introduced in one step and (2) a two-step sequence that first installs the requisite six-carbon ester side chain followed by chemoselective nitration. 相似文献
53.
Khan CB Markowitz H McCowan B 《The Journal of the Acoustical Society of America》2006,120(3):1684-1694
The goal of this research was to determine when harbor seal pup vocalizations become sufficiently distinctive to allow individual recognition. A total of 4593 calls were analyzed from 15 captive pups. Nineteen were harsh, broadband, staccato calls used in an aggressive context. The rest were tonal "mother attraction calls," having an inverted "v"- or "u"-shaped spectrogram with harmonics and a fundamental frequency around 200-600 Hz. Calls were individually distinctive even in pups less than 2 weeks old, suggesting that mothers may be able to recognize pup vocalizations at this early age. Classification rates from discriminant function analysis were generally comparable to those of other phocids and less than in otariids, supporting the theory that recognition is more highly developed in otariids. Significant differences were found between male and female pup calls, and there were significant interactions between pup sex and age. The results of this study should be interpreted with caution until the findings are verified in wild harbor seal pups. 相似文献
54.
In the capacitated team orienteering problem (CTOP), we are given a set of homogeneous vehicles and a set of customers each with a service demand value and a profit value. A vehicle can get the profit of a customer by satisfying its demand, but the total demand of all customers in its route cannot exceed the vehicle capacity and the length of the route must be within a specified maximum. The problem is to design a set of routes that maximizes the total profit collected by the vehicles. In this article, we propose a new heuristic algorithm for the CTOP using the ejection pool framework with an adaptive strategy and a diversification mechanism based on toggling between two priority rules. Experimental results show that our algorithm can match or improve all the best known results on the standard CTOP benchmark instances proposed by Archetti et al. (2008). 相似文献
55.
David A. Pérez Berrocal Dr. Thimmalapura M. Vishwanatha Dr. Daniel Horn-Ghetko J. Josephine Botsch Laura A. Hehl Dr. Sebastian Kostrhon Dr. Mohit Misra Prof. Dr. Ivan Ðikić Dr. Paul P. Geurink Dr. Hans van Dam Prof. Dr. Brenda A. Schulman Dr. Monique P. C. Mulder 《Angewandte Chemie (International ed. in English)》2023,62(32):e202303319
Protein post-translational modification with ubiquitin (Ub) is a versatile signal regulating almost all aspects of cell biology, and an increasing range of diseases is associated with impaired Ub modification. In this light, the Ub system offers an attractive, yet underexplored route to the development of novel targeted treatments. A promising strategy for small molecule intervention is posed by the final components of the enzymatic ubiquitination cascade, E3 ligases, as they determine the specificity of the protein ubiquitination pathway. Here, we present UbSRhodol, an autoimmolative Ub-based probe, which upon E3 processing liberates the pro-fluorescent dye, amenable to profile the E3 transthiolation activity for recombinant and in cell-extract E3 ligases. UbSRhodol enabled detection of changes in transthiolation efficacy evoked by enzyme key point mutations or conformational changes, and offers an excellent assay reagent amenable to a high-throughput screening setup allowing the identification of small molecules modulating E3 activity. 相似文献
56.
57.
Flexible and self-standing multilayered films made of nanoperforated poly(lactic acid) (PLA) layers separated by anodically polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) conducting layers have been prepared and used as electrodes for supercapacitors. The influence of the external layer has been evaluated by comparing the charge storage capacity of four- and five-layered films in which the external layer is made of PEDOT (PLA/PEDOT/PLA/PEDOT) and nanoperforated PLA (PLA/PEDOT/PLA/PEDOT/PLA), respectively. In spite of the amount of conducting polymer is the same for both four- and five-layered films, they exhibit significant differences. The electrochemical response in terms of electroactivity, areal specific capacitance, stability, and coulombic efficiency was greater for the four-layered electrodes than for the five-layered ones. Furthermore, the response in terms of leakage current and self-discharge was significantly better for the former electrodes than for the latter ones. 相似文献
58.
Brenda L. García Burjor Captain Richard D. Adams Ana B. Hungria Paul A. Midgley Sir John Meurig Thomas John W. Weidner 《Journal of Cluster Science》2007,18(1):121-130
The cluster complex Pt2Ru4(CO)18 was used as a precursor to prepare a 60 wt% 1:2 Pt:Ru nanoparticles on carbon (PtRu/C) for use as an electrocatalyst for
methanol oxidation. This bimetallic carbonyl cluster complex was found to provide smaller, more uniform bimetallic nanoparticle
that exhibited higher electrocatalytic activity than a 60 wt% 1:1 Pt:Ru commercial catalyst from E-Tek. Using bimetallic cluster
precursors simplifies the synthetic procedures by reducing the need for high temperature reduction and assures a more intimate
mixing of the two different metals. Transmission electron microscopy (TEM) images of the catalyst obtained from the cluster
precursor showed bimetallic nanoparticles having a narrow size range of 2–3 nm that were dispersed uniformly over the surface
of the support. Images of the commercial catalyst showed particles 3–4 nm in diameter that tended to agglomerate near the
edges of the carbon support particles. Cyclic voltammograms of methanol oxidation from the two catalysts showed significantly
higher activity for the cluster-derived catalyst. The onset potential for methanol oxidation for the cluster-derived catalyst
was approximately 170 mV lower than that of the commercial catalyst at 100 A/g Pt, and approximately 250 mV lower at 400 A/g
Pt.
* This report is dedicated to Prof. Günter Schmid on the occasion of his 70th birthday. 相似文献
59.
60.
From the resinous exudate of Heliotropium sinuatum (family Boraginaceae), a new compound: 4-(3',5'-dihydroxynonadecyl)phenol 1, together with eight previously described flavonoids, were isolated and their antioxidant activities were assessed by quenching measurements with ABTS and DPPH cation radicals. 相似文献