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91.
Heidari AH Braun RJ Hirsa AH Snow SA Naire S 《Journal of colloid and interface science》2002,253(2):295-307
The drainage of a thin liquid film with an insoluble monolayer down a vertical wall is studied. Lubrication theory is used to develop a model where the film is pinned at the top with a given thickness and the film drains into a bath at the bottom. A nonlinear equation of state is used for the surface tension and the surface viscosity is a nonlinear function of the surfactant concentration; these are appropriate for some aqueous systems. The three partial differential equations are solved via discretization in space and then the resulting differential algebraic system is solved. Results are described for a wide range of parameters, and the conditions under which the free surface is immobilized are discussed. 相似文献
92.
The heats of reaction of tolueneMo(CO)3 with a series of phosphines and phosphites have been measured by solution calorimetry. The order of stability toward formation of fac-(PR3)3Mo(CO)3 in THF solution is: P(OCH3)3s> PMe3 > PnBu3 > PMe2Ph> PEt3 > triphos> P(OPh)3 > PMePh2 > PPh3 > PCl3 and spans a range of 25 kcal/mol reflecting individual bond strength differences up to 8 kcal/mol. The bulky phosphines PCy3 and PtBu3 react with tolueneMo(CO)3 in THF, but 30–40 kcal/mol less heat is evolved in these reactions than with the other phosphines and phosphites. The coordinately unsaturated five-coordinate complexes (PR3)2Mo(CO)3 are proposed as the reaction products. The importance of both steric and electronic factors in the Mo---P bond is discussed. 相似文献
93.
This paper describes the design and synthesis of a family of pore-forming amphiphiles. Two of these amphiphiles, which are derived from cholic acid, lysine, and p-phenylenediamine, can produce pores in lipid bilayers as individual molecules. In sharp contrast, analogous amphiphiles that do not contain a rigid 1,4-phenylenediamide moiety favor the formation of dimer-based pores. Kinetic evidence in support of monomer- and dimer-based pores has been obtained from Na+ transport measurements across bilayers made from 1-palmitoyl-2-oleoyl-2-sn-glycero-3-phosphocholine (POPC). Structure-activity studies that have been carried out with pore-forming, dimer-based amphiphiles have also revealed a significant activity dependence on their overall compactness. The practical potential of pore-forming amphiphiles with controllable supramolecular properties is briefly discussed. 相似文献
94.
Reaction of camphor with hydroxylamine-O-sulfonic acid affords the nitrogen insertion product α-camphidone by migration of the methylene group rather than the bridgehead. Since Beckmann rearrangements of trigonal oximes afford bridgehead cleavage products with camphor, an alternative synchronous rearrangement of a tetrahedral intermediate is proposed for this Beckmann-like reaction. 相似文献
95.
De Jonghe S Lamote I Venkataraman K Boldin SA Hillaert U Rozenski J Hendrix C Busson R De Keukeleire D Van Calenbergh S Futerman AH Herdewijn P 《The Journal of organic chemistry》2002,67(3):988-996
The synthesis of a new series of D-erythro-homoceramide analogues is described. Several synthetic approaches were investigated. Homoceramides can be successfully synthesized from L-homoserine as chiral building block and a protected Weinreb-amide as a key intermediate. The synthesis of short-chain analogues with a heptyl side chain, as well as with a phenyl residue in the sphingoid part (instead of the naturally occurring tridecyl side chain), was effected. The homoceramides 15-17 and 24 were investigated for their potential to reverse the inhibitory effect of fumonisin B(1) on axonal growth. Unfortunately, none of the tested compounds showed any biological activity due to their lack of metabolism to glucosylhomoceramide. 相似文献
96.
The synthesis and crystal structure of Cu(6)(4,7-phenanthroline)(8)(MeCN)(4)(6+) a novel Cu(i)-molecular hexamer is described in which the metal cations and phenanthroline molecules self-assemble into a dimer of shallow triangular-shaped bowls, within which are located large spherical polyoxometalate anions PM(12)O(40)(3-)(M = Mo or W). 相似文献
97.
Three naturally occurring methyl-1,6-dioxaspiro[4.5]decanes have been prepared in good yield using organoselenium mediated reactions during the crucial cyclization process. 相似文献
98.
99.
Yuichiro Hori Miyako Nishiura Tomomi Tao Reisuke Baba Steven D. Bull Kazuya Kikuchi 《Chemical science》2021,12(7):2498
Reversible enzymatic post-translational modification of the ε-amino groups of lysine residues (e.g. N-acylation reactions) plays an important role in regulating the cellular activities of numerous proteins. This study describes how enzyme catalyzed N-deprotection of lysine residues of non-fluorescent peptide-coumarin probes can be used to generate N-deprotected peptides that undergo spontaneous O- to N-ester transfer reactions (uncatalyzed) to generate a highly fluorescent N-carbamoyl peptide. This enables detection of enzyme catalyzed N-deacetylation, N-demalonylation, N-desuccinylation and N-demethylation reactions activities towards the N-modified lysine residues of these probes using simple ‘turn on’ fluorescent assays.We developed “turn-on” fluorescent probes that detect enzymatic lysine deacylation and demethylation critical for epigenetic and other cellular phenomena, using intramolecular O- to N-ester transfer reactions. 相似文献
100.
Day JS Edwards HG Dobrowski SA Voice AM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(3):563-568
This paper describes the application of Raman spectroscopy to the detection of exogenous substances in latent fingerprints. The scenario considered was that of an individual handling a substance and subsequently depositing a contaminated fingerprint. Five drugs of abuse (codeine phosphate, cocaine hydrochloride, amphetamine sulphate, barbital and nitrazepam) and five non-controlled substances of similar appearance, which may be used in the adulteration of drugs of abuse (caffeine, aspirin, paracetamol, starch and talc), were studied in both sweat-rich and sebum-rich latent fingerprints. The substances studied could be clearly distinguished using their Raman spectra and were all successfully detected in latent fingerprints. Photobleaching was necessary to reduce the fluorescence background in the spectra of some substances. Raman spectra obtained from the substances in sweat-rich latent fingerprints were of a similar quality to spectra that obtained from the substances under normal sampling conditions. Interfering Raman bands arising from latent fingerprint material were present in the spectra obtained from the substances in sebum-rich fingerprints. These bands did not prevent identification of the substances and could be successfully removed by spectral subtraction. The most difficult aspect of the detection of these substances in latent fingerprints was visually locating the substance in the fingerprint in order to obtain a Raman spectrum. 相似文献