Multi-criteria analysis for dredger dispatching under uncertainty

Dredger dispatching is a complex decision making process in which multiple requirements and uncertain site conditions have to be taken into consideration simultaneously, for a specific dredging task. In evaluating the suitability of dredgers, besides quantitative assessments, qualitative assessments are often required to deal with uncertainty, subjectiveness and imprecision, which are best represented with fuzzy data. This paper formulates dredger dispatching as a fuzzy multi-criteria analysis model, and presents an effective algorithm for handling both crisp and fuzzy data in a straightforward manner. As a result, effective decisions can be made based on consistent evaluation results. An empirical study of a real case in China is conducted to demonstrate the applicability of the model. With its simplicity in both concept and computation, the model can be implemented as an effective decision aid in selecting dredgers for specific dredging tasks.     

Enantioselective Friedel-Crafts reaction of indoles with carbonyl compounds catalyzed by bifunctional cinchona alkaloids

In this communication, we report an efficient asymmetric Friedel-Crafts reaction that, unprecedently, is applicable to a wide range of both indoles and carbonyls. The use of a readily accessible catalyst in combination with a high enantioselectivity that is insensitive to reaction concentration, temperature, air, and moisture should allow this reaction to provide useful enantioselective access to new chiral indole derivatives. [reaction: see text]     

Pulsed photothermal phase-shift spectroscopy for weak absorption measurement

A novel photothermal phase-shift spectroscopy configuration based on the retro-reflected beam interference has been developed and its operational principle is described. The weak absorption measurement ability of this technique is experimentally proven with a water/ethanol solution of standard Pyronine G dye and the limit of detection is found to be 1.8 x 10(-6) absorbance. Potential applications of the technique are discussed.     

Expedient synthesis of the tetracyclic core of ent-nakadomarin A

An efficient eight-step assembly of the tetracyclic core (ABCD rings) of ent-(+)-nakadomarin A, a bioactive hexacyclic marine alkaloid, has been realized with Sonogashira coupling, platinum(II)-promoted cascade cyclizations, and saturation of a challenging carbon-carbon double bond through a hydroboration/oxidation/xanthate formation/Barton-McCombie deoxygenation sequence as key transformations.     

Micellization-induced conformational change of a chiral proline surfactant

A proline surfactant including two chiral carbons, sodium N-dodecanoyl-(4R)-hydroxy-L-prolinate (SDHP), has been synthesized, and its micellization behavior in aqueous solution has been investigated by 1H NMR spectroscopy. Two conformational isomers of SDHP, namely, Z and E, are discriminated in the NMR time scale, and critical micelle concentration is derived for each isomer separately. The transformation from E to Z is observed upon micellization, and the amount of Z isomer is approximately three times that of E isomer in the equilibrated system. Moreover, the variation in chemical shifts with the surfactant concentration reveals the shielding effect of the carboxyl group on the syn-side protons of the pyrrolidine ring, which implies that the pyrrolidine rings arrange in a side-to-side manner and lie parallel to the plane of the carboxyl bonds in the neighboring molecules. The difference in the directions of the carbonyl group between Z and E isomers essentially determines their different micellization abilities and molecular arrangements in the micellization process.     

Asymmetric synthesis of cis-5-tert-butylproline with metal carbenoid NH insertion

The highly stereoselective intramolecular metal carbenoid insertion reaction of sulfinimine-derived delta-amino alpha-diazoesters is used to prepare cis-5-tert-butylproline. A concerted or nearly concerted metal carbenoid N-H insertion reaction mechanism is proposed.     

Highly regioselective rearrangement of 2-substituted vinylepoxides catalyzed by gallium(III) triflate

Gallium(III) triflate catalyzed the rearrangement of 2-substituted vinylepoxides into beta,gamma-unsaturated carbonyl compounds with high regio- and chemoselectivity (>97/3) in low catalyst loading (1-5 mol %). The alkyl-substituted trimethylsilylvinyl epoxides gave beta,gamma-unsaturated ketone, but aryl-substituted vinylepoxides gave the aldehydes instead.     

Study of binding constant of toll-like receptor 4 and lipopolysaccharide using capillary zone electrophoresis

This short communication describes the interaction between toll-like receptor 4 (TLR4) and lipopolysaccharide (LPS, its specific ligand) using analytical methods. Their interaction has been evidenced in many reports. Nevertheless, there are few reports focused on their binding constant. In this research, the interaction between TLR4 and LPS is investigated using mobility shift method by CZE. To optimize the electrophoresis conditions, the effecting factors, running buffer, sample concentration, injection duration, and operation voltage of electrophoretic on the mobility shift are studied in detail. Electrophoresis conditions were described as follows: borate buffer (pH 7.4, 20 mM), 5 s for 50 mbar pressure injection duration, and 13 kV of separation voltage in 41.5 cm fused silica capillary with 75 μm id and 375?μm od. The combination constant of TLR4 and LPS is calculated using Scatchard methods. The Scatchard liner correlation is y=-0.0165x+0.1456, binding constant is K=1.65 x 10? (g/mL)?1.     

Feeding deterrents against two grain storage insects from Euphorbia fischeriana

The screening of several Chinese medicinal herbs for insecticidal principles showed that Euphorbia fischeriana roots possessed significant feeding deterrent activity against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From ethanol extract, four feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as jolkinolide B, 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate, 17-hydroxyjolkinolide A and B on the basis of their phytochemical and spectral data. Jolkinolide B and 17-hydroxyjolkinolide B possessed strong feeding deterrent activities against S. zeamais (EC?? = 342.1 and 543.9 ppm, respectively) and T. castaneum adults (E?? = 361.4 and 551.5 ppm, respectively). 17-Hydroxyjolkinolide A and 12-deoxyphorbol 13-(9Z)-octadecenoate 20-acetate A also exhibited feeding deterrent activity against the two grain storage insects with EC?? values of 631.9 and 884.3 ppm for S. zeamais and 656.5 and 1058.4 ppm for T. castaneum adults.