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1.
The positional distribution of isovaleric acid in natural cetacean triglycerides has been studied using proton magnetic resonance
with lanthanide shift reagents. Twenty-nine samples of melon, jaw, and blubber triglycerides from 13 genera in the Delphinidae,
Phocoenidae, and Monodontidae families were examined. Isovaleric acid was found esterified only at the 1,3-positions in the
monoisovaleroyl and diisovaleroyl triglycerides of these animals. 相似文献
2.
Marek Matlengiewicz 《Polymer Bulletin》1987,18(6):507-512
Summary Standard 100 MHz 1H-NMR spectrum of the PCT/FT copolyterephthalate gives little information on its microstructure and exhibits only slight splitting of the terephthalic signal which was found to be useful for evaluating distribution of compositional sequences. Application of Pr(fod)3 provides clear splitting of this signal into lines of compositional diads with traces of compositional tetrads, while Eu(fod)3 compresses the lines already split in the standard spectrum and yields one featureless broad terephthalic signal containing no microstructural information. The splitting induced by Pr(fod)3 is comparable to that obtained using a superconducting spectrometer operating at 300 MHz. 相似文献
3.
The use of Eu(fod)3 and Pr(fod)3 shift reagents for the investigation of the nuclear magnetic resonance spectra of polymers is reported for the following samples: poly(vinyl methyl ether), poly(vinyl ethyl ether), poly(vinyl acetate) and poly-(propylene oxide). 相似文献
4.
5.
Whentris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octaneodionato)europium (III)—Eu(fod)3—forms a complex with a sufficiently basic functional group in a donor molecule, the change in the magnetic environment of
protons near the coordination site causes their nuclear magnetic resonance (NMR) signals to shift to different positions.
Consequently Eu(fod)3 and other compounds that similarly affect NMR signals have been designated chemical shift reagents (csr). Because of their
ability to shift proton signals, csr substantially increase the amount of structural information that can be obtained from
NMR spectroscopy, frequently converting complicated splitting patterns into first-order spectra. Some generally useful experimental
and interpretive csr techniques are described here using methyl petroselinate and methyl oleate as examples. Csr studies of
methyl petroselinate reveal that the position of the double bond is at C-6, and that there is no chain substitution or branching
before C-9. Csr studies of methyl oleate reveal that the position of the double bond is at or beyond C-9, and that there is
no chain substitution or branching before C-6. Some suggestions are presented for expanding the amount of structural information
that can be obtained by csr studies of unsaturated lipid derivatives.
Presented in part at AOCS Meeting, Atlantic City, October, 1971. 相似文献
6.
Saowapa Chotisuwan Jatuporn Wittayakun Rodrigo J. Lobo-Lapidus Bruce C. Gates 《Catalysis Letters》2007,115(3-4):99-107
Bimetallic MgO-supported catalysts were prepared by adsorption of Pt3Ru6(CO)21(μ3-H)(μ-H)3 on porous MgO. Characterization of the supported clusters by infrared (IR) spectroscopy showed that the adsorbed species
were still in the form of metal carbonyls. The supported clusters were decarbonylated by treatment in flowing helium at 300 °C,
as shown by IR and extended X-ray absorption fine structure (EXAFS) data, and the resulting supported PtRu clusters were shown
by EXAFS spectroscopy to have metal frames that retained Pt–Ru bonds but were slightly restructured relative to those of the
precursor; the average cluster size was almost unchanged as a result of the decarbonylation. These are among the smallest
reported bimetallic clusters of group-8 metals. The decarbonylated sample catalyzed ethylene hydrogenation with an activity
similar to that reported previously for γ-Al2O3-supported clusters prepared in nearly the same way and having nearly the same structure. Both samples were also active for
n-butane hydrogenolysis, with the MgO-supported catalyst being more active than the γ-Al2O3-supported catalyst. 相似文献
7.
Feng-Fang Shue 《Fuel》1983,62(1):127-128
Ytterbium (fod)3 was used as a shift reagent in conjunction with solution 1H n.m.r. studies of asphaltene isolated from Devonian shale bitumen. Upon addition of the reagent, bands attributed to protons on alkyl groups alpha to oxygen atoms were shifted and separated from that attributed to protons alpha to two aromatic systems. Similar experiments with Green River bitumen asphaltene did not show any observable shift. The presence and absence of the ether formations in shale asphaltenes can be substantiated by 13C n.m.r. 相似文献
8.
A series of Co-Pt(Pd, Rh)/γ- Al2O3 catalysts were prepared by successive wetness impregnation. The catalytic activities for CO oxidation, NO decomposition and
NO selective catalytic reduction (SCR) by C2H4 over the samples calcined at 500°C and reduced at 450°C were determined. The activities of the samples calcined at 750°C
and reduced at 450°C for NO selective catalytic reduction (SCR) by C2H4 were also determined. All the samples were characterized by XRD, XPS, XANES, EXAFS, TPR, TPO and TPD techniques. The results
of activity measurements show that the presence of noble metals greatly enhances the activity of Co/γ-Al2O3 for CO or C2H4 oxidation. For NO decomposition, the H2-reduced Co-Pt(Pd, Rh)/γ- Al2O3 catalysts exhibit very high activities during the initial period of catalytic reaction, but with the increase of reaction
time, the activities decrease obviously because of the oxidation of surface cobalt phase. For NO selective reduction by C2H4, the reduced samples are oxidized more quickly by the excess oxygen in reaction gas. The oxidized samples possess very low
activities for NO selective reduction. The results of XRD, XPS and EXAFS indicate that all the cobalt in Co-Pt(Pd, Rh)/γ-Al2O3 has been reduced to zero valence during reduction by H2 at 450°C, but in Co/γ-Al2O3 only a part of the cobalt has been reduced to zero valence, the rest exists as CoAl2O4-like spinel which is difficult to reduce. For the samples calcined at 750°C, the cobalt exists as CoAl2O4 which cannot be reduced by H2 at 450°C and possesses better activities for NO selective reduction. The results of XANES spectra show that the cobalt in
Co/γ- Al2O3 has lower coordination symmetry than that in Co-Pt(Pd, Rh)/γ-Al2O3. This difference mainly results from the distorting tetrahedrally- coordinated Co2+ ions which have lower coordination symmetry than Co0 in the catalysts. The coordination number for the Co-Co shell from EXAFS has shown that the cobalt phase is highly dispersed
on Co-Pt(Pd, Rh)/γ- Al2O3 catalysts. The TPR results indicate that the addition of noble metals to Co/γ- Al2O3 makes the TPR peaks shift to lower temperatures, which implies the spillover of hydrogen species from noble metals to cobalt
oxides. The oxygen spillover from noble metals to cobalt is also inferred from the shift of TPO peaks to lower temperatures
and the increased amount of desorbed oxygen from TPD. For CO oxidation, the Co0 is the main active phase. For NO decomposition and selective reduction, Co0 is also catalytically active, but it can be oxidized into Co3O4 by oxygen at high reaction temperature.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
The lower jaw fat of the Amazon River dolphinInia geoffrensis contains 52.8% wax ester, 44.7% triglyceride and 2.5% diacyl glyceryl ether, while its dorsal blubber fat is >98% triglyceride.
Examination of the intact lipids, the derived fatty acids and the derived fatty alcohols by gas chromatography reveals that
the blubber triglycerides show characteristics of freshwater fish fats, but the jaw fat lipids have several distinctive features.
Jaw fat wax esters, triglycerides and diacyl glyceryl ethers are all rich in C10, C12 and C14 fatty acids and contain no polyunsaturated acids. The fatty alcohols in the wax esters are over 90% saturated. The major
carbon numbers in the jaw fat triglycerides (C38–C46) are considerably lower than those of the blubber triglycerides (C48–C54). The possible adaptation of the jaw lipids for use in the underwater echolocation process of this dolphin is discussed. 相似文献
10.
Neetha A. Khan Luis E. Murillo Yuying Shu Jingguang G. Chen 《Catalysis Letters》2005,105(3-4):233-238
The low-temperature self-hydrogenation (disproportionation) of cyclohexene was used as a probe reaction to correlate the reactivity
of Co/Pt(111) bimetallic surfaces with supported Co/Pt/γ-Al2O3 catalysts. Temperature-programmed desorption (TPD) experiments show that cyclohexene undergoes self-hydrogenation on the
~1 ML Co/Pt(111) surface at ~219 K, which does not occur on either pure Pt(111) or a thick Co film on Pt(111). Supported catalysts
with a 1:1 atomic ratio of Co:Pt were synthesized on a high surface area γ-Al2O3 to verify the bimetallic effect on the self-hydrogenation of cyclohexene. EXAFS experiments confirmed the presence of Co–Pt
bonds in the catalyst. Using FTIR in a batch reactor configuration, the bimetallic catalyst showed a higher activity toward
the self-hydrogenation of cyclohexene at room temperature than either Pt/γ-Al2O3 or Co/γ-Al2O3 catalysts. The comparison of Co/Pt(111) and Co/Pt/γ-Al2O3 provided an excellent example of correlating the self-hydrogenation activity of cyclohexene on bimetallic model surfaces
and supported catalysts. 相似文献
11.
Reaction of mononuclear Ln(fod)3 chelates (where fod is the anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and Ln = Nd, Eu, Tb and Lu) with potentially bridging ligand 2,2′-bipyrimidine (bpm) in 2:1 mole ratio in ethanol afforded new dinuclear lanthanide complexes of the form [Ln(fod)3-(μ-bpm)-Ln(fod)3]. Neodymium complex is one of the rare bipyrimidine-bridged dinuclear complexes. The absorption spectrum of the neodymium complex displays characteristic hypersensitive as well as non-hypersensitive transitions. The excitation of Eu–Eu and Tb–Tb complexes at 355 nm produces an intense red and green luminescence, respectively. 相似文献
12.
G. J. Boudreaux A. V. Bailey V. W. Tripp 《Journal of the American Oil Chemists' Society》1972,49(3):200-201
The use of a pseudo contact shift reagent, (Eu[fod]3), to obtain simplified NMR spectra of a typical long chain monounsaturated fatty acid methyl ester, methyl petroselinate,
is described. Spectra were obtained in which individual methylene groups are identifiable from their splitting patterns. Non-equivalent
splitting patterns were observed for the methine protons with varying amounts of reagent used. The effect of concentration
of the shift reagent on the chemical shift is discussed.
Presented in part at the Meeting of the Gulf Coast Instrumental Analysis Group, Houston, October 1971.
S. Market. and Nutr. Res. Div., ARS, USDA 相似文献
13.
Feeding the ethyl ester of dihomo-γ-linolenic acid for 25 days to rabbits resulted in increased PGE1 (20to30-fold) and PGE2 (1.5-fold) output by a hormone responsive, in vitro, renal papilla preparation. The relative amount of PGE1 increased from <5% of PGE2 in controls to 25–35% of PGE2 in the papillae of 20∶3ω6-supplemented animals. During the study renomedullary triglycerides in the 20∶3ω6-supplemented animals
increased 2.8-fold compared to animals fed an equal amount of a control fatty acid mixture, and in addition to a marked enrichment
in 20∶3ω6, also contained increased proportions of 20∶4ω6 and longer chain polyenes. The increase in triglyceride content
found in the renal medulla was not seen in the renal cortex or liver. There was no increase in renomedullary phospholipid
content during the study, and phopholipids of treated animals contained increased proportions of 20∶3ω6 and 20∶4ω6, but not
longer chain polyenes. The results indicate that enriching the prostaglandin precursor pool by feeding 20∶3ω6 can alter the
type and amount of prostaglandin released by the renal papilla, at least in vitro. Also, the selective changes in amount and
long chain polyene content of renomedullary triglycerides during the study suggest some special functions for this lipid class
in prostaglandin precursor metabolism. *** DIRECT SUPPORT *** A00M6131 00010 相似文献
14.
Park Joo-Hyoung Cho Hyun Ju Park Sang Jun Nam In-Sik Yeo Gwon Koo Kil Jeong Ki Youn Young Kee 《Topics in Catalysis》2007,42(1-4):61-64
Co/Pt/Ba/γ-Al2O3, Co/Ba/γ-Al2O3, Pt/Ba/γ-Al2O3, Co/Pt/γ-Al2O3, Ba/γ-Al2O3, Pt/γ-Al2O3, and Co/γ-Al2O3 type catalysts were prepared by a conventional impregnation method, and their NO
x
storage capacities were evaluated by colorimetric assay. Co-containing catalysts had a higher NO
x
storage capacity than that of Co-free counterparts. The role of each component, especially Co, for the catalysts prepared
was investigated by using in-situ FTIR. The high NO
x
storage for Co-containing catalysts including Co/Ba/γ-Al2O3 and Co/Pt/Ba/γ-Al2O3 is mainly due to the formation of Co3O4 on the catalyst surface identified by XAFS. 相似文献
15.
Zi-dong Zhang Zhi-cheng Shi Run-hua Fan Di-sheng Yao Dong-yue Zhang Jing Li 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(1):86-89
The aim of this paper is to synthesize α-(Fe, Al)2O3 solid solutions from precursors prepared by the sol–gel method. The powders were characterized by X-ray diffraction, particle
size analysis and TGA-DSC. The results indicated that the precursor prepared by sol–gel method will translate into α-(Fe,
Al)2O3 solid solutions after calcined at 1300 °C for 3 h, with the average grain size of 14 μm. And Fe2O3 reduced the temperature of the γ-Al2O to α-Al2O3 phase transition from 1,300 to 850 °C. 相似文献
16.
A novel kind of loaded photocatalyst of TiO2/SiO2/γ‐Fe2O3 (TSF) that can photodegrade effectively organic pollutants in the dispersion system and can be recycled easily by a magnetic
field is reported in this paper. The γ‐Fe2O3 cores in TiO2/γ‐Fe2O3 are found to reduce the activity of the TiO2 photocatalyst in the photodegradation of dyes under either UV or visible light irradiation. Addition of a SiO2 membrane between the γ‐Fe2O3 core and the TiO2 shell weakens efficiently the influence of the γ‐Fe2O3 cores on the TiO2 photocatalytic activity and leads to a highly active and magnetically separable photocatalyst on TSF. Comparison of the photodegradation
processes of dyes under UV and visible irradiation is also carried out.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Radioactivity from orally administered radiolabeled dihomo-γ-linolenic acid (20∶3ω6) was recovered from the liver, plasma
and brain lipid fractions. After administration the fatty acid was metabolized to arachidonic acid, the 22 carbon chain length
fatty acid, and was also β-oxidized. However, 22 hr after administration of [1-14C]20∶3 between one-third and one-half of the recovered radioactivity was still associated with dihomo-γ-linolenic acid in
the liver and plasma lipid fractions. Orally administered dihomo-γ-linolenic acid is incorporated into lipid fractions and
is, therefore, available in the metabolic pool for PGE1 synthesis. 相似文献
18.
1H-NMR and Eu(fod)3 lanthanide shift reagent were used to determine tetrad distribution of comonomer units of the PDT/FT copolyterephthalate obtained from terephthaloyl chloride (intermonomer) and 3,3′-dimethylbisphenol A and phenolphtalein (comonomers). Computer simulations of the terephthalic proton signal split into the lines of compositional tetrads were performed to obtain quantitative data. To characterize the microstructure of the copolymer samples synthesized at different temperatures, the degree of randomness and the degree of alternation were calculated. It was shown that the latter can differentiate the chains which seemed to be identical concerning the diad distribution only. 相似文献
19.
Seung-Soo Kim Jinsoo Kim Hwaung Lee Byung-Ki Na Hyung Keun Song 《Korean Journal of Chemical Engineering》2005,22(4):585-590
Spherical nanostructured γ-Al2O3 granules were prepared by combining the modified Yoldas process and oil-drop method, followed by the Pt impregnation inside
mesopores of the granules by incipient wetness method. Prepared Pt/γ-Al2O3 catalysts were reduced by novel method using plasma, which was named plasma assisted reduction (PAR), and then used for methane
conversion in dielectric-barrier discharge (DBD). The effect of Pt loading, calcination temperature on methane conversion,
and selectivities and yields of products were investigated. Prepared Pt/γ-Al2O3 catalysts were successfully reduced by PAR. The main products of methane conversion were the light alkanes such as C2H6, C3H8 and C4H10 when the catalytic plasma reaction was carried out with Pt/γ-Al2O3 catalyst. Methane conversion was in the range of 38–40% depending on Pt loading and calcination temperature. The highest
yield of C2H6 was 12.7% with 1 wt% Pt/γ-Al2O3 catalysts after calcinations at 500 ‡C. 相似文献
20.
Guosheng Peng Zaihui Fu Dulin Yin Sheng Zhong Yan Yang Ningya Yu Donghong Yin 《Catalysis Letters》2007,118(3-4):270-274
A coupled process, of which Pd/γ-Al2O3–NH4VO3 catalyzed the hydroxylation of benzene with hydrogen peroxide produced in situ by an anthraquinone (AQ) redox route, was
carried out via a sealed gaseous inner-circulated device under the atmospheric pressure. By means of such process, 0.57% of
benzene conversion, 100% of phenol selectivity and 26.6% of anthraquinone-utilized efficiency were achieved upon the mixed
Pd/γ-Al2O3–NH4VO3 (V/Pd molar ratio for 4) in the presence of benzene/acetic acid (4v/10v). Above all, after the coupled reaction system was
recycled three times, the accumulated phenol amount could achieve ca. 0.833 mmol and its average value (ca. 0.278 mmol) was
slightly higher than phenol amount obtained in the first run (ca. 0.255 mmol), indicating that such coupled reaction system
could be recycled efficiently. In addition, a synergistic mechanism was proposed to explain the favorable effect of V compound
on the Pd/γ-Al2O3 catalyst. 相似文献