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111.
112.
O. E. Ayers S. P. McManus C. U. Pittman 《Journal of polymer science. Part A, Polymer chemistry》1973,11(6):1201-1212
Ferrocenylmethyl acrylate (I) and ferrocenylmethyl methacrylate (II) have been readily copolymerized with maleic anhydride in benzene–ethyl acetate solutions. Similarly, II has been copolymerized with both acrylonitrile and N-vinyl-2-pyrrolidone in benzene solutions to give higher molecular weight copolymers in high yields. In all cases azobisisobutyronitrile has been the initiator. Based on e values obtained, the metal carbonyl substituent acts as an electron-withdrawing group. Over a wide range of comonomers (N-vinyl-2-pyrrolidone, styrene, vinyl acetate, methyl acrylate, acrylonitrile, and maleic anhydride) I and II exhibit r1 values lower than (and r2 values higher than) similar copolymerizations with methyl acrylate or methyl methacrylate. Further more, the Q values found for I (0.03–0.11) and II (0.08–0.18) are smaller than those for methyl acrylate (0.46) and methyl methacrylate (0.74). Thus, I and II are less reactive than expected, presumably due to steric effects. 相似文献
113.
Coupling of bulky,electron-deficient partners in aryl amination in the preparation of tridentate bis(oxazoline) ligands for asymmetric catalysis 总被引:2,自引:0,他引:2
A new class of tridentate bis(oxazoline) ligands 7, in which an N-phenylaniline unit links the two oxazoline rings, has been prepared. The key step in their synthesis is a Hartwig-Buchwald type Pd-catalyzed aryl amination between the two bulky o-substituted coupling partners, 2-(2'-bromophenyl)oxazolines 8 and 2-(o-aminophenyl)oxazolines 9. By varying the substituent on the coupling partners, a range of 10 ligands has been prepared in good yield. During the synthesis of 2-(o-aminophenyl)oxazolines 9a-d, a number of products of unexpected side reactions were isolated in two of the three steps. Alternatively, the required 2-(o-aminophenyl)oxazolines 9 were obtained by a DAST-promoted cyclodehydration of hydroxyamides 12a-d without formation of any byproducts. 相似文献
114.
Brian D. Wagner Shannon J. Fitzpatrick Gregory J. McManus 《Journal of inclusion phenomena and macrocyclic chemistry》2003,47(3-4):187-192
The fluorescence intensity of 7-methoxycoumarin (7MC) in aqueoussolution is found to significantly decrease upon addition of variouscyclodextrins. This observed phenomenon is described asfluorescence suppression, to distinguish it from fluorescencereduction via bimolecular quenching. The decrease in fluorescenceof 7MC is proposed to be the result of the formation of ahost–guest inclusion complex with cyclodextrin. Since 7MC isa polarity-sensitive fluorophore, which is less fluorescent ina nonpolar environment, its fluorescence decreases uponinclusion into the relatively nonpolar internal cavity of thecyclodextrin. The same equation used for extracting the associationconstant in the case of 1 : 1 host–guest inclusion-induced fluorescenceenhancement is shown to be applicable to the case of fluorescencesuppression. In the case of β-cyclodextrin, the degree of fluorescencesuppression, as well as the value of the binding constant for formationof the inclusion complex, are found to be unaffected by modificationof the cyclodextrin rims, suggesting that the molecule iscompletely included within the β-cyclodextrin cavity. In the case ofγ-cyclodextrin, the degree of fluorescence suppression, butnot the value of the binding constant, is found to be significantlyaffected by modification of the cyclodextrin rims, suggesting thatthe molecule is experiencing a less polar environment in the modifiedγ-cyclodextrin cavity. The binding constant is three timeslarger in β- as compared to γ-cyclodextrin, indicatinga much better size match in the smaller β-cyclodextrin cavity. 相似文献
115.
William J. Patterson Samuel P. McManus Charles U. Pittman 《Journal of polymer science. Part A, Polymer chemistry》1974,12(4):837-850
A new monomer, 1,1′-bis(dimethylaminodimethylsilyl)ferrocene, was synthesized by two routes and polymerized with three aryl disilanols: dihydroxydiphenylsilane, 1,4-bis(hydroxydimethylsilyl)benzene, and 4,4′-bis(hydroxydimethylsilyl)biphenyl, yielding three different polysiloxanes. Melt polymerizations carried out at 1 torr pressure and 100°C resulted in the highest molecular weight polymers. Intramolecular cyclization competed with intermolecular chain extension in polymerization of the bis(aminosilane) with dihydroxydiphenylsilane, resulting in isolation of a bridged derivative, 1,3,5-trisila-2,4-dioxa-1,1,5,5-tetramethyl-3,3-diphenyl[5]ferrocenophane. Cyclization did not compete significantly during the formation of polymers from this bisaminosilane and the two remaining diols, as evidenced by higher yields and greater molecular weights. These polymers could be cast as tough flexible films, and fibers could be drawn from their melts. TGA and DSC data showed the polymer formed from 1,1′-bis(dimethylaminodimethylsilyl)ferrocene and 1,4-bis(hydroxydimethylsilyl)benzene to be at least as thermally stable as an arylene siloxane polymer which differed from the ferrocenylsiloxane structure only in the replacement of the ferrocene moiety with a p-substituted phenylene linkage. The ferrocene-containing polymers were generally hydrolytically stable under conditions of refluxing THF–H2O(10 : 1) for 1 hr. The polymer-forming reaction was found to follow second-order kinetics, and the specific rate constants for formation of two of the polymers were measured. 相似文献
116.
A method is described for labeling and measuring the incorporation of dietary copper into hair using the enriched (99.61 atomic-%) 65Cu isotope. Natural isotope abundant copper exists as 65Cu (30.86 atomic-%) and 63Cu (69.17 atomic-%), but enriched (99.61 atomic-%) 65Cu isotope may be obtained commercially and administered to change deliberately the natural isotope abundance of copper to “label” the copper source. Natural isotope abundant copper and the enriched (99.61 atomic-%) 65Cu isotope were mixed into rat feed and administered daily by gavage. The isotope concentration was determined by neutron activation analysis (NAA). The copper concentration was determined by direct-current argon plasma (DCP) spectrometry.The measured copper isotope ratios (65Cu/Cutot)_for the natural isotope abundant copper in National Bureau of Standards Standard Reference Materials (NBS SRM) 1571 Orchard Leaves and 1577a Bovine Liver were 0.3201 ± 0.0039 and 0.3187 ± 0.0089, respectively. Measured copper isotope ratios in rat hair were 0.3100 ± 0.0606, 0.4580 ± 0.2495 and 0.2712 ± 0.0645 from rats given a standard feed that contained natural isotope abundant copper, a daily supplement of natural isotope abundant copper sulfate mixed into the standard feed and a daily supplement of copper sulfate administered by gavage, respectively. The copper isotope ratio increased to 0.5251 ± 0.2860 and 0.7235 ± 0.0704 in hair from rats given enriched 65Cu in their feed and by gavage, respectively. The statistically significant increase in the 65Cu isotope when administered by gavage demonstrates strates successful labeling of dietary copper in the hair. 相似文献
117.
A protein molecular weight map of ES2 clear cell ovarian carcinoma cells using a two-dimensional liquid separations/mass mapping technique 总被引:6,自引:0,他引:6
A molecular weight map of the protein content of ES2 human clear cell ovarian carcinoma cells has been produced using a two-dimensional (2-D) liquid separations/mass mapping technique. This method uses a 2-D liquid separation of proteins from whole cell lysates coupled on-line to an electrospray ionization-time of flight (ESI-TOF) mass spectrometer to map the accurate intact molecular weight (M(r)) of the protein content of the cells. The two separation dimensions involve the use of liquid isoelectric focusing as the first phase and nonporous silica reversed-phase high-performance liquid chromatography (HPLC) as the second phase of separation. The detection by ESI-TOF-MS provides an image of pI versus M(r) analogous to 2-D gel electrophoresis. Each protein is then identified based upon matrix-assisted laser desorption/ionization (MALDI)-TOF-MS peptide mapping and intact M(r) so that a standard map is produced against which other ovarian carcinoma cell lines can be compared. The accurate intact M(r) together with the pI fraction, and peptide map serve to tag the protein for future interlysate comparisons. An internal standard is also used to provide a means for quantitation for future interlysate studies. In the ES2 cell line under study it is shown that nearly 900 M(r) bands are detected over 17 pI fractions from pH 4 to 12 and a M(r) range up to 85 kDa and that around 290 of these bands can be identified using mass spectrometric based techniques. The protein M(r) is detected within an accuracy of 150 ppm and it is shown that many of the proteins in this human cancer sample are modified compared to the database. The protein M(r) map may serve as a highly reproducible standard Web-based method for comparing proteins from related human cell lines. 相似文献
118.
Graves Duane A. Lang Craig A. Leavitt Maureen E. 《Applied biochemistry and biotechnology》1991,(1):813-826
Client-funded bench-scale investigations concerning the likelihood of successfully applying biological remediation to hazardous
wastes must be cost-effective, and they usually need only determine if biodegradation is likely to occur on site. To assess
the potential for stimulating biodegradation, biochemical oxygen demand (BOD) was used to continuously monitor bacterial respiration
during growth on mixed organic wastes from contaminated water and soil. Continuously collected oxygen-consumption data provided
information on the overall metabolic activity of the resident bacterial population and permitted direct observation of the
cessation of microbial respiratory activity and, thus, the termination of aerobic degradation. The correlation of biological
oxygen utilization with biodegradation was confirmed using independent analytical methods. Continuous, long-term BOD analysis
was applied to bench-scale studies to assess the biodegradation of mixed organic wastes from contaminated sites and industrial
waste effluents. This information was used to make an initial determination regarding the need to further explore bioremediation
as a potential remedial-action technology using on-site, pilot-scale testing. 相似文献
119.
Alexopoulos T Allen C Anderson EW Areti H Banerjee S Beery PD Biswas NN Bujak A Carmony DD Carter T Cole P Choi Y De Bonte R Erwin A Findeisen C Goshaw AT Gutay LJ Hirsch AS Hojvat C Kenney VP Koltick D Lindsey CS LoSecco JM McMahon T McManus AP Morgan N Nelson K Oh SH Piekarz J Porile NT Reeves D Scharenberg RP Stringfellow BC Stampke SR Thompson M Turkot F Walker WD Wang CH Wesson DK 《Physical review letters》1988,60(16):1622-1625
120.
Maureen P. Edwards Peter M. Waterhouse María Jesús Munoz-Lopez Robert S. Anderssen 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2016,67(5):112
The spread of a virus through the leaf of a plant is both spatially and temporally causal in that the present status depends on the past and the spatial spread is compactly supported and progresses outwards. Such spatial spread is known to occur for certain nonlinear diffusion processes. The first compactly supported solution for nonlinear diffusion equations appears to be that of Pattle published in 1959. In that paper, no explanation is given as to how the solution was derived. Here, we show how the solution can be derived using Lie symmetry analysis. This lays a foundation for exploring the behavior of other choices for nonlinear diffusion and exploring the addition of reaction terms which do not eliminate the compactly supported structure. The implications associated with using the reaction–diffusion equation to model the spatial–temporal spread of a virus through the leaf of a plant are discussed. 相似文献