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1.
Measurements of mechanical and thermal transport properties have been made on the blends of cis-polyisoprene (CPI) and trans-polyisoprene (TPI) prepared by a solution casting method. Characterization of these blends has been done using wide angle X-ray scattering. Thermo-mechanical, mechanical, and thermal transport properties have been determined employing dynamic mechanical analyzer (DMA) and transient plane source. Storage modulus and tan δ as determined from DMA have been found to increase and decrease with the increase in TPI content, respectively. Mechanical properties such as Young’s modulus and tensile strength, as determined from strain–stress behavior of CPI/TPI blends, have been found to increase with increasing TPI content. This increase in properties has been explained on the basis of the crosslink density, calculated using theory of rubber elasticity. Thermal transport properties such as thermal conductivity, thermal diffusivity, and volumetric heat capacity are higher for all the three blends as compared to their pure components.  相似文献   

2.
Gevuina avellana and Rosa rubiginosa proteins were evaluated for their potential food use. The proteins were sequentially separated into five fractions according to their solubilities in deionized water, 0.5 M NaCl, 70% (vol/vol) isopropyl alcohol, 50% (vol/vol) glacial acetic acid, and 0.1 M NaOH. The five fractionated protein groups were then characterized by SDS-PAGE and gel filtration chromatography to determine their M.W. profiles. Ninety-six percent of G. avellana total protein was solubilized in three extraction stages, and 88% of R. rubiginosa total protein was solubilized in one extraction stage. Albumins were the major protein fraction in G. avellana and glutelins-1 the most abundant in R. rubiginosa. The protein solubility profile determined over the pH range 1–12 showed minimal solubilities at pH 3–5 and pH 3–7 for G. avellana and R. rubiginosa, respectively. Electrophoretic studies revealed the existence of proteins composed of two major kinds of polypeptides linked together via disulfide bonds and with molecular masses ranging from 13 to 119 kDa. Gel filtration chromatography profiles of globulins and albumins were studied for both seeds. Isoelectric focusing showed an isoelectric point in the ranges of 4.5–6 and 3–6.5 for G. avellana and R. rubiginosa proteins, respectively.  相似文献   

3.
The sandalwood kernels of Santalum insulare (Santalaceae) collected in French Polynesia give seed oils containing significant amounts of ximenynic acid, E-11-octadecen-9-oic acid (64–86%). Fatty acid (FA) identifications were performed by gas chromatography/mass spectrometry (GC/MS) of FA methyl esters. Among the other main eight identified fatty acids, oleic acid was found at a 7–28% level. The content in stearolic acid, octadec-9-ynoic acid, was low (0.7–3.0%). An inverse relationship was demonstrated between ximenynic acid and oleic acid using 20 seed oils. Results obtained have been compared to other previously published data on species belonging to the Santalum genus, using multivariate statistical analysis. The relative FA S. insulare composition, rich in ximenynic acid is in the same order of those given for S. album or S. obtusifolium. The other compared species (S. acuminatum, S. lanceolatum, S. spicatum and S. murrayanum) are richer in oleic acid (40–59%) with some little differences in linolenic content.  相似文献   

4.
Derivatives of 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylic acid (chrysanthemic acid) are classic natural pyrethroids discovered in pyrethrum plants and show insecticidal activity. Chrysanthemic acid, with two asymmetric carbons, has four possible stereoisomers, and most natural pyrethroids have the (1R,3R)-trans configuration. Interestingly, chrysanthemic acid–related structures are also found in insect sex pheromones; carboxylic esters of (1R,3R)-trans-(2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl)methanol (chrysanthemyl alcohol) have been reported from two mealybug species. In the present study, another ester of chrysanthemyl alcohol was discovered from the striped mealybug, Ferrisia virgata (Cockerell), as its pheromone. By means of gas chromatography–mass spectrometry, nuclear magnetic resonance spectrometry, and high-performance liquid chromatography analyses using a chiral stationary phase column and authentic standards, the pheromone was identified as (1S,3R)-(?)-cis-chrysanthemyl tiglate. The (1S,3R)-enantiomer strongly attracted adult males in a greenhouse trapping bioassay, whereas the other enantiomers showed only weak activity. The cis configuration of the chrysanthemic acid–related structure appears to be relatively scarce in nature, and this is the first example reported from arthropods.  相似文献   

5.
Poly(ethylene oxide)-block-poly(butyl acrylate) copolymers were prepared via simplified electrochemically mediated atom transfer radical polymerization (seATRP) utilizing only 1 ppm of CuII complex, which is the limit of a successful well-controlled polymerization. The presented seATRP system works under potentiostatic and galvanostatic conditions. The polymerization results showed similar molecular weight evolution while maintaining a narrow molecular weight distribution throughout the reactions. 1H NMR results confirm chemical structure of synthesized diblock copolymers. This ultralow ppm technique is promising candidate for polymerization from nanoparticles, flat surfaces, proteins, and DNA.  相似文献   

6.
In this study, we synthesized the new kinds of semiconducting polymeric gels having negative (n-type) and positive (p-type) counter ions as charge carriers. The polyacrylamide gel was doped with pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt), having \textSO3 - {\text{SO}}_{3}^{ - } ions as side groups and Na+ as counter ions, so-called p-type semiconducting gel. The doping process was performed during the polymerization where the pyranine binds to the polymer strands over OH group chemically via radical addition. In a similar way, N-isopropylacrylamide (NIPA) gel was doped with methacrylamidopropyltrimethyl ammonium chloride (MAPTAC), having Cl as counter ions, so-called n-type semiconducting gel. Here MAPTAC was embedded by copolymerization within the polymer network (NIPA). These semiconducting gels can show different electrical properties by changing the concentration of the doping agents, swelling ratio etc. We have shown that the pn junction, formed by combining p-type and n-type gels together in close contact, rectifies the current similar to the conventional Si and Ge diodes.  相似文献   

7.
The chitosan Schiff bases were synthesised through the condensation reaction of chitosan with o-, m- and p-nitrobenzaldehyde (abbreviated as CSB-o, CSB-m and CSB-p) in the ratio 1:1 and were characterised by means of FTIR, UV, XRD and SEM. The thermal dehydration and degradation kinetics of all these Schiff bases were studied using different isoconversional and maximum rate (peak) methods, viz. Kissinger–Akahira–Sunose (KAS), Tang, Starink, Flynn–Wall–Ozawa (FWO) and Bosewell from DSC data and the thermal stability from TG. The activation energy values of thermal dehydration and degradation reactions obtained from isoconversional methods of FWO and Bosewell are slightly higher than that obtained from other methods. All the isoconversional and maximum rate (peak) methods yielded consistent values of E α for both the dehydration and degradation reactions and is in the order CSB-o < CSB-m < CSB-p. The Schiff bases observed (from TG) the same order of thermal stability.  相似文献   

8.
Few studies report the individual effect of 9c,11t- and 10t,12c-CLA on human energy metabolism. We compared the postprandial oxidative metabolism of 9c,11t- and 10t,12c-CLA and oleic acid (9c-18:1) in 22 healthy moderately overweight volunteers. After 24 weeks supplementation with 9c,11t-, 10t,12c-CLA or 9c-18:1 (3 g/day), subjects consumed a single oral bolus of the appropriate [1-13C]-labeled fatty acid. 8 h post-dose, cumulative oxidation was similar for 9c-18:1 and 10t,12c (P = 0.66), but significantly higher for 9c,11t (P < 0.01).  相似文献   

9.
Rhamnolipids are a class of biosurfactants that have a great potential to be used in industries. Five proteins/enzymes, namely RhlA, RhlB, RhlC, RhlG and RhlI, are critical for the production of rhamnolipids in Pseudomonas aeruginosa. Four of the 5 proteins except RhlC were successfully over-expressed in E. coli and three of them (RhlA, RhlB and RhlI) were purified and obtained in milligram quantities. The purified proteins were shown to be folded in solution. Homology models were built for RhlA, RhlB and RhlI. These results lay a basis for further structural and functional characterization of these proteins in vitro to favor the construction of super strains for rhamnolipids production.
  相似文献   

10.
The autoxidation processes of the cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) isomers of CLA were separately observed at ca. 0% RH and different temperatures. The t10,c12 CLA oxidized faster than the c9,t11 isomer at all tested temperatures. The first half of the oxidation process of t10,c12 CLA obeyed an autocatalytic-type rate expression, but the latter half followed first-order kinetics. On the other hand, the entire oxidation process of c9,t11 CLA could be expressed by the autocatalytic-type rate expression. The apparent activation energies and frequency factors for the autoxidation of the isomers were estimated from the rate constants obtained at various temperatures based on the Arrhenius equation. The apparent activation energies for the CLA isomers were greater than those for the nonconjugated n−6 and n−3 PUFA or their esters. However, the enthalpyentropy compensation held during the autoxidation of both the CLA and PUFA. This suggested that the autoxidation mechanisms for the CLA and PUFA were essentially the same.  相似文献   

11.
Ethanolic extract of aerial parts of Artemisia annua L. and artemisinin were evaluated as anti-insect products. In a feeding deterrence assay on Epilachna paenulata Germ (Coleoptera: Coccinellidae) larvae, complete feeding rejection was observed at an extract concentration of 1.5 mg/cm2 on pumpkin leaf tissue. The same concentration produced a feeding inhibition of 87% in Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae). In a no-choice assay, both species ate less and gained less weight when fed on leaves treated with the extract. Complete mortality in E. paenulata and 50% mortality in S. eridania were observed with extract at 1.5 mg/cm2. Artemisinin exhibited a moderate antifeedant effect on E. paenulata and S. eridania at 0.03–0.375 mg/cm2. However, a strong effect on survival and body weight was observed when E. paenulata larvae were forced to feed on leaves treated at 0.03 and 0.075 mg/cm2. Artemisia annua ethanolic extract of aerial parts at 1.5 mg/cm2 showed no phytotoxic effect on pumpkin seedlings.  相似文献   

12.
The hydrocarbons (3Z,6Z,9Z)-3,6,9-octadecatriene (3Z,6Z,9Z-18:H) and (3Z,6Z,9Z)-3,6,9-nonadecatriene (3Z,6Z,9Z-19:H) constitute the pheromone of the winter moth, Erannis bajaria. These compounds belong to a large group of lepidopteran pheromones which consist of unsaturated hydrocarbons and their corresponding oxygenated derivatives. The biosynthesis of such hydrocarbons with an odd number of carbons in the chain is well understood. In contrast, knowledge about the biosynthesis of even numbered derivatives is lacking. We investigated the biosynthesis of 3Z,6Z,9Z-18:H by applying deuterium-labeled precursors to females of E. bajaria followed by gas chromatography–mass spectrometry analysis of extracts of the pheromone gland. A mixture of deuterium-labeled [17,17,18,18-2H4]-3Z,6Z,9Z-18:H and the unlabeled 3Z,6Z,9Z-18:H was obtained after topical application and injection of (10Z,13Z,16Z)-[2,2,3,3-2H4]-10,13,16-nonadecatrienoic acid ([2,2,3,3-2H4]-10Z,13Z,16Z-19:acid) or (11Z,14Z,17Z)-[3,3,4,4-2H4]-11,14,17-icosatrienoic acid ([3,3,4,4-2H4]-11Z,14Z,17Z-20:acid). These results are consistent with a biosynthetic pathway that starts with α-linolenic acid (9Z,12Z,15Z-18:acid). Chain elongation leads to 11Z,14Z,17Z-20:acid, which is shortened by α-oxidation as the key step to yield 10Z,13Z,16Z-19:acid. This acid can be finally reduced to an aldehyde and decarbonylated or decarboxylated to furnish the pheromone component 3Z,6Z,9Z-18:H. A similar transformation of 11Z,14Z,17Z-20:acid yields the second pheromone component, 3Z,6Z,9Z-19:H.  相似文献   

13.
In batch chromatography, solvent-gradient operations (SG) produce significant improvement in terms of the enrichment of products and the separation time and the solvent consumption as compared with isocratic operations. This work studied solvent-gradient operation in reversed-phase simulated moving bed unit to separate ortho-xylene and para-xylene. In a solvent-gradient mode, different mobile phase compositions lead to a different retention behavior of solutes, i.e., different adsorption isotherms. Frontal analysis experiments for ortho-xylene and para-xylene were carried out with a reversed-phase column to measure adsorption parameters at several different mobile phase compositions, such as 45%, 50%, 60%, 75% and 90% acetonitrile. Therefore, the parameters in the retention model for solvent-gradient operation in the case of reversed-phase chromatography were estimated and applied to the design of an SMB system. A modified design method for solvent-gradient simulated moving bed chromatography (SG-SMB) was proposed. The robust operating conditions were obtained within the separation region on (φ R , φ E ) plane (φ R and φ E are the volumetric content of organic modifier in the raffinate and the extract streams, respectively). The performance results of isocratic and solvent-gradient SMB were compared. A partial-discard strategy and increasing of the solvent gradient level were also applied to improve the performance of the SG-SMB.  相似文献   

14.
Lesquerella fendleri is a promising new crop whose seed contains hydroxy FATG with potential industrial uses as well as substantial amounts of valuable gums. The defatted L. fendleri seeds also contain more than 30% protein. The objective of this study is to process and characterize this protein component for possible future uses in food. Hexane-defatted seed has more than 30% protein content. Defatted lesquerella meal was extracted sequentially with 0.5 M sodium chloride (2×), water, 70% ethanol, and 0.1 N sodium hydroxide (2×). Each sodium chloride extract was dialyzed against deionized water and centrifuged to separate the water-soluble fraction (albumin) from the salt-soluble fraction (globulin) before freeze-drying. The ethanol extract and the neutralized sodium hydroxide extracts (glutelin) were dialyzed against water and freeze-dried. Albumin had the highest proportion of lysine and sulfur amino acids per 16 g nitrogen among all the fractions analyzed. Glutelin and globulin accounted for the highest amount of protein nitrogen. SDS-PAGE of the reduced albumin, globulin, and glutelin showed the presence of several protein bands with M.W. ranging from 7 to 98 kDa. Nitrogen solubility of defatted lesquerella meal from pH 2 to 12 indicated a solubility minimum of 15% around pH 4.2 and a solubility of 75% at pH 11.5. Nonprotein nitrogen of defatted meal was 12% of total nitrogen. Defatted lesquerella meal has the potential for food use based on good nitrogen solubility and good amino acid composition.  相似文献   

15.
A series of N-allyl, N-ethylmethacrylate and N-phenylmethacrylatenaphthalimide monomers have been prepared with –C=CFc, –C≡CFc and –C≡CSiMe3 substituents at the 4-position of the naphthalimide ring. All have been characterised by elemental analysis and spectroscopy; the X-ray structure of N-allyl-4-ethenylferrocenylnapththalimide is also reported. Free-radical polymerisation of these monomers gave homopolymers, random co- and terpolymers with polydispersities ranging from 1.7 to 3.2. Incorporation into a polymer matrix has no effect on the spectroscopic and electrochemical properties of the naphthalimide or ferrocenyl components. The ferrocenyl polymers are electrochromic and when oxidised give naphthalimide charge-transfer bands in the NIR; this electrochromism was examined by OTTLE techniques.  相似文献   

16.
N,N,N-Trimethyl chitosan, a highly water soluble derivative of chitosan, has been made by reductive methylation of chitosan by a three-step process reported in literature. A novel polyelectrolyte complex of this derivative with gellan gum has been made by mixing the aqueous solutions of the two polymers. The complex was characterized by FTIR, TGA, DSC and SEM techniques. Maximum yield of the complex was obtained at pH 2.0 with a gellan gum:trimethylchitosan ratio of 3:1. The swelling study indicated pH responsiveness of the polyelectrolyte complex sample, with higher swelling under neutral or slightly basic conditions. In vitro studies on the release of the drug ketoprofen from the polyelectrolyte complex matrix were conducted in simulated gastric and intestinal fluids. The results indicated release of 85–90 % of the entrapped drug in the media of pH 6.8 and 7.4 and less than 7 % release in the medium of pH 1.2. The kinetic analysis indicated the drug release to be a first-order process. The mechanism of water transport and drug diffusion is shown to be of Fickian type. The results prove the suitability of the polyelectrolyte complex as a matrix material for delivery of drugs with short half life such as ketoprofen in the slow release mode.  相似文献   

17.
Yellow-cedar, Callitropsis nootkatensis, is prevalent in coastal forests of southeast Alaska, western Canada, and inland forests along the Cascades to northern California, USA. These trees have few microbial or animal pests, attributable in part to the distinct groups of biologically active secondary metabolites their tissues store for chemical defense. Here we summarize the new yellow-cedar compounds identified and their biological activities, plus new or expanded activities for tissues, extracts, essential oils and previously known compounds since the last review more than 40 years ago. Monoterpene hydrocarbons are the most abundant compounds in foliage, while heartwood contains substantial quantities of oxygenated monoterpenes and oxygenated sesquiterpenes, with one or more tropolones. Diterpenes occur in foliage and bark, whereas condensed tannins have been isolated from inner bark. Biological activities expressed by one or more compounds in these groups include fungicide, bactericide, sporicide, acaricide, insecticide, general cytotoxicity, antioxidant and human anticancer. The diversity of organisms impacted by whole tissues, essential oils, extracts, or individual compounds now encompasses ticks, fleas, termites, ants, mosquitoes, bacteria, a water mold, fungi and browsing animals. Nootkatone, is a heartwood component with sufficient activity against arthropods to warrant research focused toward potential development as a commercial repellent and biopesticide for ticks, mosquitoes and possibly other arthropods that vector human and animal pathogens.  相似文献   

18.
Goldenseal (Hydrastis canadensis L.) is a popular medicinal plant distributed widely in North America. The rhizome, rootlets, and root hairs produce medicinally active alkaloids. Berberine, one of the Hydrastis alkaloids, has shown antifungal activity. The influence of a combination of the major Hydrastis alkaloids on the plant rhizosphere fungal ecology has not been investigated. A bioassay was developed to study the effect of goldenseal isoquinoline alkaloids on three Fusarium isolates, including the two species isolated from Hydrastis rhizosphere. The findings suggest that the Hydrastis root extract influences macroconidia germination, but that only the combined alkaloids—berberine, canadine, and hydrastine—appear to synergistically stimulate production of the mycotoxin zearalenone in the Fusarium oxysporum isolate. The Hydrastis root rhizosphere effect provided a selective advantage to the Fusarium isolates closely associated with the root tissue in comparison with the Fusarium isolate that had never been exposed to Hydrastis.  相似文献   

19.
Avato P  Rosito I  Papadia P  Fanizzi FP 《Lipids》2005,40(10):1051-1056
As a continuation of our study on plants of the Sapindaceae, the chemical composition of the oil extracted from seeds of Allophylus natalensis (Sonder) De Winter and of A. dregeanus (Sonder) De Winter has been investigated. The oil from both species contained approximately equal amounts of TAG and type I cyanolipids (CL), 1-cyano-2-hydroxymethylprop-2-en-1-oldiesters, with minor amounts of type III CL, 1-cyano-2-hydroxymethylprop-1-en-3-ol-diesters. Structural investigation of the oil components was accomplished by chemical, chromatographic (TLC, CC, GC, and GC-MS), and spectroscopic (IR, NMR) means. GC and GC-MS analysis showed that C20 FA were dominant in the CL components of the oil from the two species (44–80% vs. 21–26% in TAG), with cis-11-eicosenoic acid (36–46%) and cis 13-eicosenoic acid (paullinic acid, 23–37%) as the major esterified fatty acyl chains in A. natalensis and A. dregeanus, respectively. cis-Vaccenic acid was particularly abundant (11–31%) in the CL from A. dregeanus, whereas eicosanoic acid (10–22%) was also a major component of CL in both species.  相似文献   

20.
The fatty acid composition of the seed oil of 19 wild legume species from southern Spain was analyzed by gas chromatography. The main seed oil fatty acids ranged from C14:0 to C20:0. Among unsaturated fatty acids, the most abundant were linoleic, oleic and linolenic acids, except for Lathyrus angulatus, L. aphaca, L. clymenum, L. sphaericus and L. nigricans where C18:3 contents were higher than C18:1 contents. Palmitic acid was the most abundant saturated acid in studied species, ranging from 11.6% in Lathyrus sativus to 19.3% in Lens nigricans. All studied species showed higher amounts of total unsaturated fatty acids than saturated ones. Among studied species, the ω6/ω3 ratio was variable, ranging from 2.0% in L. nigricans to 13.8% in L. sativus, there being eight species in which the ω6/ω3 ratio was below 5. The fatty acids observed in these plants supports the use of these plants as a source of important dietary lipids.  相似文献   

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