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81.
Poly(amide-carbonate)s and poly(amide-thiocarbonate)s derived from the diphenol-amides N-(2,6-dichloro-4-nitrophenyl)-2,2-bis(hydroxyphenyl)-propylamide (I), N-(2,6-dichloro-4-nitrophenyl)-3,3-bis(hydroxyphenyl)-butylamide (II), and N-(2,6-dichloro-4-nitrophenyl)-4,4-bis(hydroxyphenyl)-pentylamide (III), and phosgene or thiophosgene, have been synthesized under phase transfer conditions using several quaternary ammonium salts
as phase transfer catalysts. Benzyltriethylammonium chloride (BTEAC) was effective in practically all cases due the hydrophilicity
of this catalysts.
Received: 21 February 1997/Revised: 28 April 1997/Accepted: 30 April 1997 相似文献
82.
M. Manzano M. Urueña M. Sužnjević E. Calle J. A. Hernández M. Matijasevic 《Multimedia Systems》2014,20(5):451-470
Cloud gaming is a new paradigm that is envisaged to play a pivotal role in the video game industry in forthcoming years. Cloud gaming, or gaming on demand, is a type of online gaming that allows on-demand streaming of game content onto non-specialised devices (e.g. PC, smart TV, etc.). This approach requires no downloads or game installation because the actual game is executed on the game company’s server and is streamed directly to the client. Nonetheless, this revolutionary approach significantly affects the network load generated by online games. As cloud gaming presents new challenges for both network engineers and the research community, both groups need to be fully conversant with these new cloud gaming platforms. The purpose of this paper is to investigate OnLive, one of the most popular cloud gaming platforms. Our key contributions are: (a) a review of the state-of-the-art of cloud gaming; (b) reverse engineering of the OnLive protocol; and (c) a synthetic traffic model for OnLive. 相似文献
83.
Volatile Emissions Triggered by Multiple Herbivore Damage: Beet Armyworm and Whitefly Feeding on Cotton Plants 总被引:5,自引:3,他引:5
Plants are commonly attacked by more than one species of herbivore, potentially causing the induction of multiple, and possibly competing, plant defense systems. In the present paper, we determined the interaction between feeding by the phloem feeder silverleaf whitefly (SWF), Bemisia tabaci Gennadius (B-biotype = B. argentifolii Bellows and Perring), and the leaf-chewing beet armyworm (BAW), Spodoptera exigua Hübner, with regard to the induction of volatile compounds from cotton plants. Compared to undamaged control plants, infestation with SWF did not induce volatile emissions or affect the number and density of pigment glands that store volatile and nonvolatile terpenoid compounds, whereas infestation by BAW strongly induced plant volatile emission. When challenged by the two insect herbivores simultaneously, volatile emission was significantly less than for plants infested with only BAW. Our results suggest that tritrophic level interactions between cotton, BAW, and natural enemies of BAW, that are known to be mediated by plant volatile emissions, may be perturbed by simultaneous infestation by SWF. Possible mechanisms by which the presence of whiteflies may attenuate volatile emissions from caterpillar-damaged cotton plants are discussed. 相似文献
84.
F. Fraga P. Payo E. Rodríguez‐Núñez J. M. Martínez‐Ageitos C. Castro‐Díaz 《应用聚合物科学杂志》2007,103(6):3931-3935
The physical aging of the epoxy network consisting of a diglycidyl ether of bisphenol A, m‐xylylenediamine, and polyetherimide was studied by differential scanning calorimetry. The glass transition temperature and the variation of the specific heat capacities have been calculated using the method, based on the intersection of both enthalpy–temperature lines for glassy and liquid states. The apparent activation energy (EH) was calculated using a single method that involved separate temperature and excess enthalpy dependency. All calorimetric data were compared with those obtained for the epoxy network without thermoplastic. thermoplastic. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3931–3935, 2006 相似文献
85.
Jeung Hee Lee Kerby C. Jones Thomas A. Foglia Alberto Nuñez Jong Ho Lee Yu Mi Kim Phuong-Lan Vu Ki-Teak Lee 《Journal of the American Oil Chemists' Society》2007,84(3):211-217
Using a 1,3-regioselective lipase as a catalyst, soybean oil and olive oil were interesterified with the short-chain triacylglycerol
tributyrin (1,2,3-tributyrylglycerol) to produce mixtures of structured triacylglycerols (SL-TAG). The SL-TAG were purified
by column chromatography and analyzed by both normal-phase (silica column; NPSIL) and reversed-phase [octadecyl silane (ODS) column] high-performance liquid chromatography (HPLC). Individual SL-TAG molecular
species were detected by evaporative light-scattering detection, and characterized by mass spectrometry. NPSIL HPLC successfully separated the newly synthesized SL-TAG into two groups of TAG: one composed of one butyryl group and two
long-chain fatty acyl groups (from soybean or olive oil); the second was composed of two butyryl groups and one long-chain
fatty acyl group. The SL-TAG species were further analyzed by reversed-phase HPLC which gave a more detailed separation of
the TAG species present in the two SL-TAG. 相似文献
86.
Helen L. Ngo Alberto Nuñez Wenbin Lin Thomas A. Foglia 《European Journal of Lipid Science and Technology》2007,109(3):214-224
Branched‐chain (bc) saturated fatty acids (SFA) have potential as oleochemical intermediates since they have better oxidative stability than linear unsaturated fatty acids (UFA) and have better low‐temperature properties than linear SFA. Previous studies in converting UFA to bc‐FA using clay catalysts have resulted in only modest yields and conversions. Recent reports, however, have suggested that certain zeolites can be effective catalysts for converting UFA to bc‐FA in higher yields and conversions. In this work, we examined the scope and potential of the zeolite‐catalyzed synthesis of bc‐FA starting from readily available monounsaturated linear FA. Our results show that common UFA such as oleic acid can be converted to bc‐isomers using modified Ferrierite zeolite catalysts with high conversions (98%) and high selectivity (85%) and that the zeolite catalysts are reusable for at least three cycles. The positions of branching (methyl) on the FA chain were determined from the GC‐MS spectra of the picolinyl esters of the bc‐FA. 相似文献
87.
Victor T. Wyatt Alberto Nuñez Thomas A. Foglia William N. Marmer 《Journal of the American Oil Chemists' Society》2006,83(12):1033-1039
Novel oligomeric prepolymers were synthesized by acid-catalyzed condensation of glycerol with iminodiacetic, azelaic, or succinic
acid. The prepolymers were obtained, on average, in 62% yield and were characterized by 13C NMR, 1H NMR, matrix-assisted laser desorption ionization-time of flight-mass spectrometry, and gel permeation chromatography. The
synthesized oligomers had an average M.W. of 1543 Daltons (average polydispersity (PD)=1.34, average degree of polymerization
(DOP)=5.5). Hyperbranching was evident in the oligomers produced when using azelaic acid and succinic acid as co-monomers
with glycerol, whereas the reaction between iminodiacetic acid and glycerol resulted in linear products bearing cyclic urethane
structures. 相似文献
88.
M. Cartens E. Molina Grima A. Robles Medina A. Giménez Giménez J. Ibáñez González 《Journal of the American Oil Chemists' Society》1996,73(8):1025-1031
Eicosapentaenoic acid (EPA, 20∶5n-3) was obtained from the marine microalgaePhaeodactylum tricornutum by a three-step process: fatty acid extraction by direct saponification of biomass, polyunsaturated fatty acid (PUFA) concentration
by formation of urea inclusion compounds, and EPA isolation by semipreparative high-performance liquid chromatography (HPLC).
Alternatively, EPA was obtained by a similar two-step process without the PUFA concentration step by the urea method. Direct
saponification of biomass was carried out with two solvents that contained KOH for lipid saponification. An increase in yield
was obtained because the problems associated with emulsion formation were avoided by separating the biomass from the soap
solution before adding hexane for extraction of insaponifiables. The most efficient solvent, ethanol (96%) at 60°C for 1 h,
extracted 98.3% of EPA. PUFA were concentrated by the urea method with a urea/fatty acid ratio of 4∶1 at a crystallization
temperature of 28°C and by using methanol and ethanol as urea solvents. An EPA concentration ratio of 1.73 (55.2∶31.9) and
a recover yield of 78.6% were obtained with methanol as the urea solvent. This PUFA concentrate was used to obtain 93.4% pure
EPA by semipreparative HPLC with a reverse-phase, C18, 10 mm i.d.×25-cm column and methanol/water (1% acetic acid), 80∶20 w/w, as the mobile phase. Eighty-five percent of EPA
loaded was recovered, and 65.7% of EPA present inP. tricornutum biomass was recovered in highly pure form by this three-step downstream process. Alternatively, 93.6% pure EPA was isolated
from the fatty acid extract (without the PUFA concentration step) with 100% EPA recovery yield. This two-step process increases
the overall EPA yield to 98.3%, but it is only possible to obtain 20% as much EPA as that obtained by three-step downstream
processing. 相似文献
89.
Effects of allelochemicals on plant respiration and oxygen isotope fractionation by the alternative oxidase 总被引:8,自引:1,他引:8
The goal of this investigation was to determine the effects of allelochemicals on plant respiration that thereby may be responsible for their role in growth inhibition. We have tested the effects of juglone, quercetin, cinnamic acid, and-pinene on respiration rates, and electron partitioning through the cytochrome and alternative respiratory pathways, by measuring on-line oxygen consumption and oxygen isotope fractionation in soybean cotyledon tissue. Cinnamic acid and-pinene decreased the oxygen consumption rate and increased the relative partitioning of electron transport to the alternative pathway. Possible biochemical mechanisms of these effects are discussed. 相似文献
90.
E. Rivera-Muñoz D. Lardizabal G. Alonso A. Aguilar M.H. Siadati R.R. Chianelli 《Catalysis Letters》2003,85(3-4):147-151
MCM-41- and silica gel-supported MoS2 catalysts were prepared. MCM-41 was synthesized and impregnated with precursor, then activated to obtain the active phase. The sol–gel method was used for providing the SiO2 support as well as for including the catalyst precursors in one single step of preparation. Such catalysts have applications particularly in hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) processes. A comparison of the activities of the catalysts was made. The catalytic activity results showed the method of preparation used in this study was successful in producing very efficient catalysts for the HDS of dibenzothiophene (DBT).A higher selectivity for direct C–S bond cleavage was observed for the MoS2 catalyst supported on SiO2 by the sol–gel method. X-ray diffraction studies showed that the catalysts were poorly crystallized with a very weak intensity of the (002) line of 2H-MoS2. 相似文献