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741.
W. B. Nilsson E. J. Gauglitz Jr. J. K. Hudson V. F. Stout J. Spinelli 《Journal of the American Oil Chemists' Society》1988,65(1):109-117
Supercritical fluid CO2 was used to fractionate menhaden oil fatty acid ethyl esters to obtain concentrates of the esters of allcis-5,8,11,14,17-eicosapentaenoic acid (EPA) and allcis-4,7,10,13,16,19-docosahexaenoic acid (DHA). Separation of the ethyl esters was found to occur primarily by carbon number,
thus limiting the degree to which the ethyl esters of EPA and DHA could be concentrated. Urea fractionation of whole esters
in order to remove saturates, monoenes and dienes prior to fractionation with supercritical fluid CO2 resulted in concentrates of EPA and DHA in purities exceeding 90%. Several criteria are given for the selection of crude
oils in order to maximize both purity and yield of concentrates. 相似文献
742.
Younsook Shin Kyunghee Son Dong Il Yoo Sam Hudson Marian McCord Suzanne Matthews Yoon‐Jung Whang 《应用聚合物科学杂志》2006,100(6):4306-4310
The surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmospheric pressure He/O2 plasma treatment. Accessibility of the modified PET nonwoven has been investigated in terms of crystallinity, surface chemical composition, hydrophilicity, and dye uptake. Differential scanning calorimetry (DSC) for crystallinity measurement and X‐ray photoelectron spectroscopy (XPS) for chemical composition measurement were used. Surface morphology was studied by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Percentage crystallinity increased due to the depletion of amorphous region by plasma etching. Redeposition of etched particles was observed. Oxygen‐based functional groups on the surface of PET increase from 27 to about 32% after 90 s exposure. Wettability increases by more than 10 times and moisture regain increases by three times, compared with the untreated sample. Dye uptake was not changed significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4306–4310, 2006 相似文献
743.
Joseph P. Fletcher Guy F. Hudson Srini Raghavan Subhash H. Risbud 《Journal of the American Ceramic Society》1989,72(9):1744-1746
Flow microcalorimetry was used for an investigation of the surface chemical nature of glass surfaces. A commercially available flow microcalorimeter allowed for the measurement of heat energy changes during surface reactions of two different glass powders with pyridine and water solutions. Pure fused silica glass and a fluorozirconate glass were the materials studied by flow microcalorimetry. 相似文献
744.
Five natural gem diamonds which included type IA, IB and IIA specimens, have been investigated by ion beam spectrochemical analysis (IBSCA) to determine the total hydrogen impurity concentration in the diamonds. These data were compared with that obtained from other conventional techniques such as infrared and ultraviolet absorption spectroscopy, electron spin resonance and transmission electron microscopy (TEM). IBSCA indicated that all the specimens appeared to contain 1 at. % of hydrogen contrary to the infrared evidence. The highest hydrogen concentration was recorded by a type IB specimen which contained small ( 3nm) bubbles. The hydrogen concentration did not correlate with any defect within the specimens, for example the {100} planar faults, and appeared to be a general impurity. No evidence was found to suggest that inclusions were responsible for the impurity. 相似文献
745.
The electrospinning of silk fibroin(SF)/chitosan(CS) blends with different composition ratios was performed with formic acid as a spinning solvent. The SF/CS blends containing up to the CS content of 30% could be electrospun into the continuous fibrous structure, although pure CS was not able to be electrospun into the fibrous structure. As-spun SF/CS blend nanofibers showed smaller diameter and narrower diameter distribution than pure SF nanofibers, and the diameter gradually decreased from 450 to 130 nm with the addition of CS in blends. However, at the blend compositions with above 40 wt% chitosan, the continuous SF nanofibers containing CS beads were produced. We also investigated the influence of the methanol treatment on the secondary structure of as-spun SF or SF/CS blend nanofibers by means of ATR-IR and solid-state CP-MAS 13C-NMR. Comparing with the pure SF nanofibers, the conformational change of the as-spun SF/CS blend nanofibers into β-sheet was faster because the CS with rigid backbone synergistically might promote the conformational transition of SF by an intermolecular interaction. 相似文献
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747.
An investigation of the factors influencing the degree of exfoliation of an organically modified clay in a series of epoxy resins is reported. The use of sonication, choice of curing agent, effect of the moisture content of the clay, and the cure temperature were examined. The dispersion was characterized using a combination of rheological measurements, X‐ray diffraction, and dynamic mechanical thermal analysis. Rheological analysis of the clay dispersion in the epoxy monomer indicated that at high clay loads Herschel–Bulkley type behavior is followed. Higher cure temperatures and higher levels of clay moisture were found to influence the extent of exfoliation. Improvements in physical properties were observed through the addition of nanocomposites. The DGEBA/DDM and DEGEBA/DDS exhibited 2 and 4°C increase, respectively, in Tg per wt % of added clay. DGEBF showed virtually no enhancement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
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