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1.
Matthew R. Miller Nigel B. Perry Elaine J. Burgess Susan N. Marshall 《Journal of the American Oil Chemists' Society》2011,88(4):509-516
The lipid profiles of the two most important New Zealand marine oil sources were investigated, with particular attention to
the regioisomeric compositions of triacylglycerides (TAG), using 13C-nuclear magnetic resonance analysis. Oils from hoki (Macruronus novaezelandiae) and Greenshell™ mussel (Perna canaliculus) (GSM) were analyzed for their lipid content, lipid class and fatty acid profile. The regiospecific distribution of long
chain (C ≥ 20) polyunsaturated fatty acids (LC-PUFA) between the sn-1,3 and sn-2 glycerol positions was calculated from 13C responses in the carbonyl region in the triacylglycerol fraction. Rendered hoki oil (RHO) produced from the viscera and
filleting discards, had a similar lipid profile to that of hoki liver oil (HLO) confirming that the liver is the major source
of oil in RHO. The regioisomeric distribution of fatty acids showed differences between the two oil sources. Docosahexaenoic
acid (DHA) had a regioisomeric distributional preference to the sn-2 position in TAG from all the oils (59.2% HLO, 54.3% RHO and 63.4% GSM). Eicosapentaenoic acid (EPA) had a more even distribution
along the triacylglycerol backbone in hoki TAG (29.1% HLO, 33.6% RHO) while there was a slight sn-2 positional preference in the GSM TAG (37.6%). This regioisomeric information is vital to distinguish LC-PUFA-rich marine
oils from other marine sources for authentication purposes. 相似文献
2.
Two light emitting molecules with the cyano group at different positions on the vinylene i.e., 2,5-bis(2-thienyl-1-cyanovinyl)-1-(2_-ethylhexyloxy)-4-methoxybenzene (-TPT) and 2,5-bis(2-thienyl-2-cyanovinyl)-1-(2-ethylhexyloxy)-4-methoxybenzene (-TPT), and corresponding polymers, i.e., poly[2,5-bis(2-thienyl-1-cyanovinyl)-1-(2-ethylhexyloxy)-4-methoxybenzene] (denoted as P1) and poly[2,5-bis(2-ethienyl-2-cyanovinyl)-1-(2-ethylhexyloxy)-4-methoxybenzene] (denoted as P2) were synthesized. -TPT and -TPT, respectively, were blended into two host polymers, poly(methyl methacrylate (PMMA) and poly(9-vinylcarbazole) (PVK), to study the optical properties of the dopants in different host polymer matrices. Although -TPT and -TPT have the same backbone structure, their optical properties are much different. The PL emission maximum (
max) of -TPT was found blue-shifted, compared with that of -TPT, while the PL intensity of -TPT was stronger than that of -TPT. Concentration effect in the optical properties was found, 1 wt% of -TPT in PVK had the maximum fluorescent emission.The PL maximum peak wavelengths for polymer films (P1 and P2) were found red-shifted; while their PL intensities were weaker when compared with those of blends. 相似文献
3.
In the present study, we have discussed the bulk ring opening polymerization (ROP) of rac-lactide (rac-LA) and ε-caprolactone (ε-CL) using Cd(OAc)2. Cd(OAc)2 appeared to be a good catalyst for the polymerization of rac-LA and ε-CL yielding high molecular weight (M n) polymers with narrow molecular weight distributions (MWDs). The catalytic activity of the system can be increased markedly upon using catalytic amount of BnOH as external alcoholic initiator. There is a first order dependence of the rate constant with respect to monomer concentrations as understood from the kinetic studies. The rate was found to be faster in the presence of BnOH. The polymerization process was controlled. The polymerization proceeded via the coordination-insertion mechanism without BnOH as well as activated monomer mechanism in the presence of BnOH. In the absence of BnOH, the acetyl group initiated the polymerization as understood from the 1H NMR and MALDI-TOF analysis. The benzyloxy group initiated the polymerization in the presence of BnOH. Moderate activity towards the polymerization of ethylene was observed using MAO as alkyl aluminum activator. The polymerization parameters towards the polymerization of ethylene were widely investigated. 相似文献
4.
5.
A novel ∈-lysine acylase (N
6-acyl-l-lysine amidohydrolase; EC 3.5.1.17) was isolated from Streptomyces mobaraensis and purified to homogeneity by SDS-PAGE from the culture broth. The purified enzyme was monomeric, with a molecular mass
of approximately 60 kDa. The enzyme was inactivated by the presence of 1,10-phenanthroline and activated in the presence of
Co2+ and Zn2+. The enzyme showed a pH optimum of 8.0 and was stable at temperatures of up to 50°C for 1 h at pH 8.0. The enzyme specifically
catalyzed the hydrolysis of the amide bond of various N∈-acyl-l-lysines. Furthermore, the enzyme efficiently catalyzed the synthesis of N∈-acyl-l-lysines with fatty and aromatic acyl groups in an aqueous buffer. In the syntheses of N∈-decanoyl-l-lysine, N∈-lauroyl-l-lysine, and N∈-myristoyl-l-lysine, the product precipitated and the yield was 90% or higher using 10 mM FA and 0.5 M l-lysine as the substrate. 相似文献
6.
A model is described, which makes it possible to calculate the distribution of nonequilibrium carriers and an electric field near the p–n junction, which arose as a result of the internal photoeffect. Using laser illumination, the possibilities to control the properties of nanolayered structures sensitive to the concentration of free carriers are analyzed. The mutual location of the region of the intense absorption of radiation and the p–n junction itself is varied and the linear and square mechanisms of carrier recombination are analyzed. 相似文献
7.
Sobotník J Hanus R Kalinová B Piskorski R Cvacka J Bourguignon T Roisin Y 《Journal of chemical ecology》2008,34(4):478-486
The behavioral and electroantennographic responses of Prorhinotermes canalifrons to its soldier frontal gland secretion, and two separated major components of the secretion, (E)-1-nitropentadec-1-ene and (E,E)-α-farnesene, were studied in laboratory experiments. Behavioral experiments showed that both the frontal gland secretion
and (E,E)-α-farnesene triggered alarm reactions in P. canalifrons, whereas (E)-1-nitropentadec-1-ene did not affect the behavior of termite groups. The alarm reactions were characterized by rapid walking
of activated termites and efforts to alert and activate other members of the group. Behavioral responses to alarm pheromone
differed between homogeneous and mixed groups, suggesting complex interactions. Antennae of both soldiers and pseudergates
were sensitive to the frontal gland secretion and to (E,E)-α-farnesene, but soldiers showed stronger responses. The dose responses to (E,E)-α-farnesene were identical for both soldiers and pseudergates, suggesting that both castes use similar receptors to perceive
(E,E)-α-farnesene. Our data confirm (E,E)-α-farnesene as an alarm pheromone of P. canalifrons. 相似文献
8.
S. S. Ordan’yan S. V. Vikhman Yu. S. Nagaeva 《Refractories and Industrial Ceramics》2009,50(2):127-130
Sections are constructed for WSi2–Me
VB2 of the quaternary systems W–Si–(V, Nb, Ta)–B described by eutectic diagrams of state with T
eut (1940 ± 20), (1980 ± 20) and (2020 ± 30)°C and a boride content in the eutectics of 35, 20 and 15 mol.% respectively.
Translated from Novye Ogneupory, No. 3, pp. 41 – 44, March 2009. 相似文献
9.
Contribution of legumes towards N economy in cereal-based cropping systems is well-known but there has been a gradual decline
in the cultivation of grain legumes, threatening sustainability of maize (Zea mays)–wheat (Triticum aestivum) cropping system in north-western India. A study was made to evaluate and quantify the effect of different grain legumes
on productivity, profitability, N economy and soil fertility in maize–wheat cropping system at New Delhi during 2002–2004.
Five legumes, viz. blackgram (Vigna mungo), greengram (Vigna radiata), cowpea (Vigna unguiculata), groundnut (Arachis hypogaea) and soybean (Glycine max) were either intercropped with maize or grown in sole cropping, and their residues were incorporated before the following
crop of wheat, which was grown with varying rates of N, viz. 0, 40, 80 and 120 kg N ha−1. Maize-equivalent productivity was significantly more with intercropped greengram (16.1–29.9%), cowpea (24.8%) and groundnut
(11.1–16.6%) than in sole maize. Land equivalent ratio and other competitive functions were favourably influenced with intercropped
maize + greengram and maize + cowpea. Addition of N through legume residues varied from 11.5–38.5 kg ha−1 in intercropped system and 17.5–83.5 kg ha−1 in sole cropping, which improved productivity of following wheat to a variable extent. Nitrogen economy in wheat was 21 kg ha−1 due to residue incorporation of intercropped greengram, cowpea and groundnut; and 49–56 kg N ha−1 of sole cropped greengram and groundnut. Residual soil fertility in terms of organic C and KMnO4-N showed an improvement under maize-based intercropping systems followed by wheat, and the beneficial effect was more pronounced
with sole cropping of legumes due to greater addition of residues. Apparent N balance as well as actual change in KMnO4-N at the end of study was positive in most intercropped legumes as well as sole cropping systems, with greater improvement
noticed under groundnut, soybean and greengram. Net returns were marginal with maize-based intercropping or sole cropping
of legumes, but improved considerably with wheat, particularly when greengram, cowpea and groundnut were grown in the previous
season. The studies suggested that inclusion of grain legumes, particularly greengram, cowpea and groundnut was beneficial
for improving productivity, profitability, N economy and soil fertility in maize–wheat cropping system. 相似文献
10.
To study the activity of the different desaturases present in the pheromone biosynthetic pathway of the Egyptian armyworm,
Spodoptera littoralis, we prepared a series of mono-and gem-difluorinated analogs of myristic acid with halogen substitution at the C8–C11 positions of the aliphatic chain via specifically positioned dithiane precursors. Thus, transformation of dithianes by treatment with N-bromosuccinimide in the presence of H2O followed by reduction with LiAIH4 afforded the appropriate alcohols, which reacted with diethylaminosulfur trifluoride to give rise to the corresponding monofluoroderivative
intermediates. Alternatively, the introduction of the gem-difluoro functionality was carried out by reaction of the appropriate dithiane intermediate with 1,3-dibromo-5,5-dimethylhydantoin
in the presence of HF/pyridine. The activity of these fluorinated FA as substrates and inhibitors of the desaturases involved
in the biosynthesis of the sex pheromonal blend of S. littoralis has been studied. In this case, 11-fluorotetradecanoic acid elicited a moderate inhibitory activity of Δ11 desaturase. 相似文献
11.
V. G. Kulichikhin L. K. Golova I. S. Makarov G. N. Bondarenko A. K. Berkovich S. O. Ilyin 《Polymer Science Series C》2016,58(1):74-84
Combined solutions of cellulose and an acrylonitrile-based copolymer in N-methylmorpholine-N-oxide have been prepared for the first time, new composite fibers have been formed, and the properties of the solutions and fibers under standard conditions and during thermal treatment have been studied. On the basis of studying the phase state and morphological peculiarities of combined cellulose solutions with polyacrylonitrile additives, it has been shown that the completed solutions make emulsions in the entire range of investigated concentrations. The rheological behavior of combined solutions changes with temperature. With the use of IR spectroscopy methods, it has been found that the addition of polyacrylonitrile to cellulose results in the association of nitrile groups with hydroxyl groups of cellulose, which favors the cyclization of CN groups during heating and the appearance of polyconjugated bonds in polyacrylonitrile chains. Thermal transformations of cellulose and polyacrylonitrile in the course of mixed-fiber carbonization have been studied via DSC and TGA. It has been shown that polyacrylonitrile inhibits the dehydration processes in cellulose and reduces the intensity of the peak due to the first stage of the structural rearrangement, i.e., acts as a “catalyst” of pyrolysis. 相似文献
12.
Florian J. Stadler 《Korean Journal of Chemical Engineering》2011,28(3):954-963
Several ethylene homopolymers and ethene/ α-olefin-copolymers with crystallinities ranging between 85 and 12% were characterized by dynamic-mechanical measurements.
The occurring relaxations were correlated to the crystallinity of the polymeric materials and to morphology. The α-relaxation, being attributed to interlamellar shear, was found to be around 60 °C with activation energies of about 120 kJ/mol
in samples with more than 42% crystallinity. The β-transition shows a much greater variety among the different samples characterized. Its relaxation temperatures vary between
−40 and 10 °C with activation energies between 200 and 400 kJ/mol. The α- and β-relaxation of several quenched samples with crystallinities between 63 and 42% were found to overlap, thus producing bimodal
maxima and different activation energies from the Arrhenius plots. A separation of these overlapping relaxations was only
possible by measuring the relaxations over a frequency range of more than three orders of magnitude. 相似文献
13.
The possibility of increasing the laminar flame velocity in a hydrogen-air mixture by excitation of O2 molecules into the a
1Δ
g
singlet state. The presence of 10% of O2(a
1Δ
g
) molecules in oxygen is demonstrated to result in noticeable (up to 50%) enhancement of mixture burning. The temperature
of combustion products and also the concentrations of H2O, NO, and other constituents increase. The greatest effect of O2(a
1Δ
g
) molecules is manifested in combustion of lean mixtures; the least pronounced effect is observed in rich mixtures. These
effects are caused by intensification of the chain mechanism in the presence of a super-equilibrium amount of excited O2(a
1Δ
g
) molecules in a hydrogen-air mixture.
__________
Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 4, pp. 3–12, July–August, 2008. 相似文献
14.
Gibb AR Suckling DM El-Sayed AM Bohman B Unelius CR Dymock JJ Larsen ML Willoughby BE 《Journal of chemical ecology》2007,33(4):839-847
The grass webworm Herpetogramma licarsisalis (Lepidoptera: Crambidae), which has recently established in pasture in Northland, New Zealand, is an important pest of many
tropical and subtropical grasses. Two pheromone components, (Z)-11-hexadecen-1-yl acetate (Z11–16:Ac) and (11Z,13E)-hexadecadien-1-yl acetate (Z11,E13–16:Ac), were identified in pheromone gland extracts of female moths by gas chromatography (GC), GC-electroantennographic
detection, and GC-mass spectrometry in conjunction with microchemical tests (dimethyldisulfide and 4-methyl-1,2,4-triazoline-3,5-dione
derivatizations). Z11,E13–16:Ac and its geometric isomer (11E,13Z)-hexadecadien-1-yl acetate (E11,Z13–16:Ac) were synthesized via stereoselective Wittig reactions, and the identity of the diene present in the pheromone glands
was confirmed to be Z11,E13–16:Ac. Field bioassays at Indooroopilly in Brisbane, Australia, established that Z11,E13–16:Ac was necessary and sufficient for attraction of male grass webworm moths and that the corresponding alcohol, (11Z,13E)-hexadecadien-1-ol (Z11,E13–16:OH), had a strong inhibitory effect on trap catches at the ratios tested. When mixed with Z11,E13–16:Ac in various ratios, Z11–16:Ac had no effect on the attractiveness of lures.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Sui-Lou Wang Jun-She Sun Bei-Zhong Han Xiao-Zong Wu 《Korean Journal of Chemical Engineering》2008,25(3):513-516
High hydrostatic pressure (HHP) technology was used for improving the ability of β-carotene biosynthesis of Rhodotorula glutinis R68. After the treatments of five repeated cycles at 300 MPa for 15 min, the barotolerant mutant PR68 was obtained. After
72 h of culture, the biomass of mutant PR68 was 21.6 g/L, decreased by 8.5% compared to the parent strain R68, but its β-carotene production reached 19.4 mg/L, increased by 52.8% compared to the parent strain R68. The result of restriction fragment
length polymorphism analysis suggested that mutant strain PR68 was likely to change in nucleic acid level, and thus enhanced
β-carotene production in this strain was a result of gene mutation induced by HHP treatment. HHP technology seems a promising
approach for improving industrial microbes. 相似文献
16.
Florian J. Stadler 《Korean Journal of Chemical Engineering》2011,28(10):2057-2063
The temperature- and frequency-dependent dynamic-mechanical properties in the temperature regime of the γ-transition were determined for a number of polyethylenes and ethylene/α-olefin-copolymers differing in their crystallinity and crystal morphology. The temperature dependence of the γ-transition was found to obey the Arrhenius law for thermally activated processes. The γ-transition temperature determined at a frequency of 1 Hz and the corresponding activation energy were analyzed as a function
of the crystallinity. As an overall trend, both quantities are found to decrease with decreasing crystallinity, which is explained
by the increase in free volume due to the incorporation of short-chain branches or the thermal pretreatment (e.g., quenching).
Taking into account that the crystal morphology of polyethylenes can be classified into four different groups, a more detailed
picture appears. Within one type of morphology both quantities, namely the transition temperature and the activation energy,
increase with decreasing crystallinity independent of the α-olefin used as the comonomer. These findings can be explained by partial orientations of the molecule segments in the interlamellar
amorphous space in the case of HDPE or by the increased steric hindrance of the crankshaft motion by the short-chain branches.
From the findings of this series of studies, it was concluded that the glass transition in polyethylene and polyethylene/α-olefin-copolymers is the β- and not the γ-transition. 相似文献
17.
L. Alonso P. Cuesta S. E. Gilliland 《Journal of the American Oil Chemists' Society》2009,86(4):337-342
The aim of this study was to evaluate the effect of β-cyclodextrin (β-CD) on trans C18:1 fatty acid isomers, conjugated linoleic acid (CLA), polyunsaturated fatty acids (PUFA) and phospholipids in pasteurized
milk. The individual trans C18:1 isomers were not significantly affected by the β-CD. trans-11 C18:1 (vaccenic acid) was found to be the major isomer (1.31 ± 0.12%) followed by trans-15 C18:1 (0.35 ± 0.06%). Individual trans linoleic acids did not show differences from the effect of β-CD, representing the high amount of the isomer trans-11 cis-15 C18:2 (0.433 ± 0.087%). The main CLA isomer cis-9 trans-11 C18:2 (rumenic acid) did not show differences between the control milk (0.672 ± 0.080%) and β-CD milk (0.663 ± 0.074%). PUFA and omega-3 and -6 fatty acids were not also significant by the effect of β-CD. Total phospholipids were not significantly affected by effect of the β-CD (0.023 ± 0.001% vs. 0.022 ± 0.001%). β-CD is a effective oligosaccharide for cholesterol removal from pasteurized milk and does not significantly affect the lipid
components of the milk fat. 相似文献
18.
Won-Jong Hong Mao Ueda Shinji Iwamoto Saburo Hosokawa Kenji Wada Masashi Inoue 《Catalysis Letters》2012,142(1):32-41
Abstract
Ce–Mn mixed oxides with a Mn/(Ce + Mn) molar ratio of 0.25 were prepared by solvothermal (ST-1) and co-precipitation (CP) methods, and Ba was loaded on the Ce–Mn oxides. In addition, CeO2–MnO x –BaO catalysts with various compositions were directly prepared by the solvothermal (ST-2) method. The NO decomposition activities of these catalysts were examined. Among the catalysts examined, the ST-2 catalyst having a nominal composition of Ce0.8Mn0.15Ba0.05O x exhibited the highest activity; 77% NO conversion to N2 was attained at 800 °C. These catalysts were characterized by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The Raman and XPS results indicate that the CP catalyst had larger amounts of the BaMnO3-δ and/or Mn3O4 phases. The ST-1 and ST-2 catalysts had highly dispersed Ba species on the surface. The ST-2 catalyst had Mn species with the lowest binding energy of Mn 2p and also had a high population of oxygen vacancies in the ceria lattice, suggesting that Mn species with a low oxidation state contributes to the formation of oxygen vacancies, which play an important role in this reaction. 相似文献19.
The Δ9-fatty acid desaturase is a key enzyme in the synthesis of unsaturated fatty acids. The fatty acid composition of membrane
phospholipids in Psychrobacter urativorans is characterized by a high degree of desaturation at Δ9 position. Based on CODEHOP-mediated PCR strategy, a novel gene designated
as PuFAD9, putatively encoding a Δ9-fatty acid desaturase (PuFAD9), was isolated from P. urativorans. The gene consists of 1,455 bp and codes for 484 amino acids. Analysis of the amino acid sequence reveals three histidine
clusters and a hydropathy profile, typical for membrane-bound desaturases. Activity of the PuFAD9 protein, recombinantly expressed in Escherichia coli was confirmed by GC-MS analysis of the cellular fatty acid composition. It was found that the ratio between palmitoleic and
palmitic acid in E. coli cells heterologously expressing the PuFAD9 gene was significantly affected by IPTG induction and the growth temperature. 相似文献
20.
A. R. Sharma Ratan Singh S. K. Dhyani R. K. Dube 《Nutrient Cycling in Agroecosystems》2010,87(2):187-197
Mulching with vegetative materials is a highly beneficial and widely-investigated agro-technique in rainfed areas but the
adoption of this practice has been constrained due to non-availability of mulch biomass locally. Live mulching with fast-growing
annual green manure legumes like sunnhemp (Crotalaria juncea) or prunings of Leucaena leucocephala grown as hedge rows can be done for moisture conservation as well as nutrient cycling in the maize–wheat cropping system,
which is predominantly followed in the high rainfall sub-mountainous region of north-western India. A field experiment was
conducted at Selakui, Dehradun during 2000–2004 to study the effect of legume mulching, viz. in situ grown sunnhemp and Leucaena prunings, along with varying N levels, viz. 0, 30, 60 and 90 kg N ha−1 (to maize), and 0, 40 and 80 kg N ha−1 (to wheat) on productivity, soil moisture conservation and soil physico-chemical properties. Intercropped sunnhemp added
0.75–1.45 t dry matter and 21.6–41.3 kg N ha−1 at 30–35 days, while Leucaena twigs added 1.89–4.15 t dry matter and 75.2–161.3 kg N ha−1 at 60–65 days of maize growth. Live mulching with sunnhemp or Leucaena biomass improved soil moisture content at maize harvest (+1.15–1.57%) and crop productivity by 6.8–8.8% over no mulching.
Combined use of both the mulching materials was more effective in improving the soil moisture content (+2.08–2.29%) and grain
yield (15.1%) over their single application. Response of maize to N fertilizer application was significant up to 90 kg N ha−1, and it was relatively more pronounced under the mulching treatments. Residual effect of mulching on wheat showed an increase
in yield of 10.2% with sunnhemp or Leucaena, and 27.9% with sunnhemp + Leucaena. There was an improvement in organic C and total N status of soil, and a decrease in bulk density associated with an increase
in infiltration rate due to mulching at the end of 4 cropping cycles. It was concluded that legume mulching is a highly beneficial
practice for enhanced moisture and nutrient conservation, leading to increased productivity and soil health of maize–wheat
cropping system under Doon valley conditions of north-western India. 相似文献