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1.
Werner Landmann N. V. Lovegren R. O. Feuge 《Journal of the American Oil Chemists' Society》1960,37(1):1-4
Summary Films of cocoa butter, highly hydrogenated cottonseed oil, mixtures of highly hydrogenated cottonseed oil and cottonseed oil,
chocolate liquor, and sweet milk chocolate were prepared; and their permeability to water vapor was determined by the cup
method. The permeability constant was calculated in terms of grams of water diffusing through a centimeter cube in one second
under a vapor pressure gradient of one millimeter of mercury across the cube.
Under the test conditions employed, the permeability constant for cocoa butter at room temperature was found to vary from
5.8×10−12 to 81.6×10−12. The permeability constants for the highly hydrogenated cottonseed oil and the cocoa butter, under comparable conditions
at room temperature, was found to be approximately 1.3×10−12 and 33×10−12, respectively.
From data obtained with cocoa butter it was concluded that the permeability constant increased with moderate increases in
film thickness.
Polymorphism was found to have a large effect on permeability, an approximately 15-fold difference was found between quickly
chilled and tempered films of cocoa butter at 3°C. (37.4°F.).
The percentage of liquid component in the fat was found to have a large effect on permeability. The increasing of the percentage
of liquid cottonseed oil in highly hydrogenated cottonseed oil from 0 to 40% increased the permeability constant from 1.3×10−12 to about 420×10−12.
The permeability of chocolate liquor and sweet milk chocolate at room temperature was increased greatly when the relative
humidity on the wet side of the films was increased to 100%. The nonfat components absorbed enough moisture to impair the
structure of the film.
Presented at the 32nd Fall Meeting of the American Oil Chemists' Society, Chicago, Ill., October 20–22, 1958.
Fellow, National Confectioners' Association.
One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S.
Department of Agriculture. 相似文献
2.
C. Bello L. L. Diosady W. F. Graydon L. J. Rubin 《Journal of the American Oil Chemists' Society》1985,62(11):1587-1592
Dichlorodicarbonylbis (triphenylphosphine) ruthenium (II), RuCl2 (CO)2 (PPh3)2, was investigated as a catalyst for edible oil hydrogenation in a preliminary screening of potential catalysts for producing
partially hydrogenated fats with lowtrans-isomer content. Refined, bleached and deodorized canola oil was hydrogenated using 1.77 × 10−5 − 6.64 × 10−4 mol/kg-oil of ruthenium catalyst equivalent to 1.79 × 10−4 − 6.71 × 10−3 wt% Ru. The effects of temperature (50–180 C) and pressure (50–750 psig) on reaction rate,trans-isomer content and fatty acid composition were examined. The activities of RuCl2 (CO)2 (PPh3)2 and nickel (Nysel HK-4 and AOCS standard nickel catalyst) were compared on a molar basis. At 4.40 × 10−4 mol/kg-oil (0.0026 wt/Ni or 0.0044 wt% Ru), 140 C and 50 psig, the nickel catalysts were completely inactive, but the ruthenium
catalyst produced an IV drop of 40 units in 60 min. At 110 C, 750 psig and 1.34 × 10−4 mol/kg-oil (1.35 × 10−3 wt% Ru), a hydrogenation rate of 0.89 ΔIV/min and a maximumtrans-isomer content of 10.4% (IV=45.0) was obtained with the ruthenium catalyst. 相似文献
3.
High functional ophthalmic lens materials, poly(HEMA-co-MMA)s, were prepared by the copolymerization of HEMA, MMA, NVP, EDGMA, and N,N-dimethylacrylamide in the presence of silver
nanoparticles. Silver nanoparticles have antimicrobial properties and a hydrophilic monomer N,N-dimethylacrylamide has excellent
biocompatibility and oxygen transmissibility. The water content was in the range of 36.63–44.45%, indicating the characteristics
of general water-content contact lenses, and the refractive index was measured to be in the range of 1.423–1.435. Meanwhile,
the oxygen transmissibility ranged from 10.63×10−11 to 18.85×10−11 (cm2/sec)(mlO2/ml×mmHg) increasing with increasing the addition ratio of N,N-dimethylacrylamide. The polymeric materials satisfied the basic
characteristics required for ophthalmic contact lenses. The polymers can be used to fabricate antimicrobial hydrogel contact
lenses with high oxygen transmissibility. 相似文献
4.
A kinetic study of the reaction between a tocopheroxyl radical and unsaturated fatty acid esters has been undertaken. The
rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl oleate2, ethyl linoleate3, ethyl linolenate4, and ethyl arachidonate5) by the tocopheroxyl radical (5,7-diisopropyltocopheroxyl6) in benzene have been determined spectrophotometrically. The second-order rate constants, k3, obtained are 1.04×10−5 M−1s−1 for2, 1.82×10−2 M−1s−1 for3, 3.84×10−2 M−1s−1 for4, and 4.83×10−2 M−1s−1 for5 at 25.0°C. Thus, the rate constants, kabstr/H, given on an available hydrogen basis are k3/4=2.60×10−6 M−1s−1 for2, k3/2=9.10×10−3 M−1s−1 for3, k3/4=9.60×10−3 M−1s−1 for4, and k3/6=8.05×10−3 M−1s−1 for5. The kabstr/H values obtained for the polyunsaturated fatty acid esters3,4, and5 containing H-atoms activated by two π-electron systems are similar to each other, and are about three orders of magnitude
higher than that for the ethyl oleate2 containing H-atoms activated by a single π-system. From these results, it is suggested that the prooxidant effect of α-tocopherol
in edible oils and fats may be induced by the above hydrogen abstraction reaction. 相似文献
5.
Şenol Alpat Sibel Kılınç Alpat Zekerya Dursun Azmi Telefoncu 《Journal of Applied Electrochemistry》2009,39(7):971-977
A new biosensor for the voltammetric detection of hydrogen peroxide was developed based on immobilization of catalase on a
clinoptilolite modified carbon paste electrode using bovine serum albumin and glutaraldehyde. The biosensor response was evaluated
according to electrode composition, reaction time, solution pH and temperature. The voltammetric signals were linearly in
proportion to H2O2 concentration in the range 5.0 × 10−6–1.0 × 10−3 M with a correlation coefficient of 0.9975. The detection limit is 8.0 × 10−7 M and the relative standard deviation for 4.0 × 10−4 M hydrogen peroxide was 1.83% (n = 6). The biosensor exhibited high sensitivity, and it was determined that it could be used for more than 2 months. In addition,
the biosensor was successfully applied for the determination of hydrogen peroxide in milk samples. 相似文献
6.
Effects of quenching mechanisms of carotenoids on the photosensitized oxidation of soybean oil 总被引:2,自引:0,他引:2
The effects of 0, 1.0 × 10”−5, 2.5 × 10−5, and 5.0 × 10−5 M β-apo-8'-carotenal, β-carotene, and canthaxanthin on the photooxidation of soybean oil in methylene chloride containing
3.3 × 10−9 M chlorophyll b were studied by measuring peroxide values and conjugated diene content. β-Apo-8'-carotenal, β-carotene, and
canthaxanthin contain 10,11, and 13 conjugated double bonds, respectively. The peroxide values and conjugated diene contents
of oils containing the carotenoids were significantly lower (P<0.05) than those of control oil containing no carotenoid. As
the number of conjugated double bonds of the carotenoids increased, the peroxide values of soybean oils decreased significantly
(P<0.05). The quenching mechanisms and kinetics of the carotenoids in the photosensitized oxidation of soybean oil were studied
by measuring peroxide values. The steady-state kinetics study showed that carotenoids quenched singlet oxygen to reduce chlorophyll-sensitized
photooxidation of soybean oil. The singlet-oxygen quenching rate constants ofβ- apo-8'-carotenal, β-carotene, and canthaxanthin were 3.06 × 109, 4.60 × 109, and 1.12 × 1010 M−1sec−1, respectively. 相似文献
7.
Kyu-Suk Hwang Sang-Wook Park Dae-Won Park Kwang-Joong Oh Seong-Soo Kim 《Korean Journal of Chemical Engineering》2009,26(5):1383-1388
Rubidium carbonate was used as an adsorbent to capture carbon dioxide from gaseous stream of carbon dioxide, nitrogen, and
moisture in a fixed-bed to obtain the breakthrough data of CO2. Experiments were carried out at flow rates of carbon dioxide and nitrogen (5×10−6–35×10−6 m3/min), moisture (0.5×10−6–3.0×10−6 m3/h), amount of adsorbent (0.5×10−3–1.8×10−3 kg), mole fraction of carbon dioxide (0.03–0.22), and different sorption temperatures (323–353 K) at atmospheric pressure.
The deactivation model in the non-catalytic heterogeneous reaction systems was used to analyze the sorption kinetics among
carbon dioxide, carbonate, and moisture, employing the experimental breakthrough data that fit the deactivation model better
than the adsorption isotherm models in the literature. 相似文献
8.
The effects of microwave drying on moisture content, moisture ratio, drying time and effective moisture diffusivity of purslane
leaves (Portulaca oleracea L.) were investigated. By increasing the microwave output power (180–900W) and the sample amounts (25–100 g), the drying time
decreased from 43 to 12.5 minutes and increased from 27 to 54 minutes, respectively. To determine the kinetic parameters,
the drying data were fitted to various models based on the ratios of the differences between the initial and final moisture
contents and equilibrium moisture content versus drying time. Among the models proposed, the semi-empirical Midilli et al.
model gave a better fit for all drying conditions applied. By increasing the microwave output power and decreasing the sample
amount, the effective moisture diffusivity values ranged from 5.913×10−11 to 1.872×10−10 m2/s and from 9.889×10−11 to 3.292×10−11 m2/s, respectively. The activation energy was calculated using an exponential expression based on the Arrhenius equation. 相似文献
9.
Mahdie Motahary Sayed Mehdi Ghoreishi Mohsen Behpour Mahshid Golestaneh 《Journal of Applied Electrochemistry》2010,40(4):841-847
A multi-walled carbon nanotubes (MWCNTs)–tetradecyltrimethylammonium bromide (TTAB) film-coated graphite electrode (GE) was
fabricated, and the electrochemical oxidation of ascorbic acid (AA) was studied in Britton–Robinson (B–R) buffer (pH 7.0)
using cyclic, square wave, and differential pulse voltammetry (CV, SWV, and DPV). An electroanalytical study of AA and acetaminophen
(ACOP) and of several mixtures of these compounds in different ratios was made. A sensitive linear voltammetric response for
AA was obtained for the concentration range of 5 × 10−7 to 1.7 × 10−4 mol L−1, with a correlation coefficient of 0.992, and the detection limit for AA was found to be 1.1 × 10−7 mol L−1 using DPV. The relative standard deviation (RSD) was 2.7%, suggesting that the film electrode has excellent day-to-day reproducibility.
The proposed voltammetric approach was also applied to the determination of the AA concentration in commercial tablets. 相似文献
10.
G. A. Nagana Gowda Narasimhamurthy Shanaiah Amanda Cooper Mary Maluccio Daniel Raftery 《Lipids》2009,44(6):527-535
Bile acids constitute a group of structurally closely related molecules and represent the most abundant constituents of human
bile. Investigations of bile acids have garnered increased interest owing to their recently discovered additional biological
functions including their role as signaling molecules that govern glucose, fat and energy metabolism. Recent NMR methodological
developments have enabled single-step analysis of several highly abundant and common glycine- and taurine- conjugated bile
acids, such as glycocholic acid, glycodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, taurodeoxycholic acid,
and taurochenodeoxycholic acid. Investigation of these conjugated bile acids in human bile employing high field (800 MHz)
1H-NMR spectroscopy reveals that the ratios between two glycine-conjugated bile acids and their taurine counterparts correlate
positively (R
2 = 0.83–0.97; p = 0.001 × 10−2–0.006 × 10−7) as do the ratios between a glycine-conjugated bile acid and its taurine counterpart (R
2 = 0.92–0.95; p = 0.004 × 10−3–0.002 × 10−10). Using such correlations, concentration of individual bile acids in each sample could be predicted in good agreement with
the experimentally determined values. These insights into the pattern of bile acid conjugation in human bile between glycine
and taurine promise useful clues to the mechanism of bile acids’ biosynthesis, conjugation and enterohepatic circulation,
and may improve our understanding of the role of individual conjugated bile acids in health and disease.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
Kang Du Weihua Liu Shuang Qiao Changli Zhou Wei Cao 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(4):881-885
It is found that nucleic acids can greatly enhance the fluorescence intensity of morin–nanoTiO2. Under optimum conditions, the enhanced fluorescence intensity of the system is in proportion to the concentration of nucleic
acids in the range of 2.0 × 10−8 to 2.2 × 10−7 g mL−1 for calf thymus DNA (ctDNA) and 1.0 × 10−8 to 2.5 × 10−7 g mL−1 for yeast RNA (yRNA). The detection limits are 4.8 × 10−9 g mL−1 for ctDNA and 1.2 × 10−9 g mL−1 for yRNA, respectively. This method has satisfactorily been used for the determination of nucleic acids in actual sample. 相似文献
12.
Kinetic Study of the Prooxidant Effect of α-Tocopherol. Hydrogen Abstraction from Lipids by α-Tocopheroxyl Radical 总被引:1,自引:0,他引:1
Aya Ouchi Masaharu Ishikura Kensuke Konishi Shin-ichi Nagaoka Kazuo Mukai 《Lipids》2009,44(10):935-943
A kinetic study of the prooxidant effect of α-tocopherol was performed. The rates of allylic hydrogen abstraction from various
unsaturated fatty acid esters (ethyl stearate 1, ethyl oleate 2, ethyl linoleate 3, ethyl linolenate 4, and ethyl arachidonate 5) by α-tocopheroxyl radical in toluene were determined, using a double-mixing stopped-flow spectrophotometer. The second-order
rate constants (k
p) obtained are <1 × 10−2 M−1 s−1 for 1, 1.90 × 10−2 M−1 s−1 for 2, 8.33 × 10−2 M−1 s−1 for 3, 1.92 × 10−1 M−1 s−1 for 4, and 2.43 × 10−1 M−1 s−1 for 5 at 25.0 °C. Fatty acid esters 3, 4, and 5 contain two, four, and six –CH2– hydrogen atoms activated by two π-electron systems (–C=C–CH2–C=C–). On the other hand, fatty acid ester 2 has four –CH2– hydrogen atoms activated by a single π-electron system (–CH2–C=C–CH2–). Thus, the rate constants, k
abstr/H, given on an available hydrogen basis are k
p/4 = 4.75 × 10−3 M−1 s−1 for 2, k
p/2 = 4.16 × 10−2 M−1 s−1 for 3, k
p/4 = 4.79 × 10−2 M−1 s−1 for 4, and k
p/6 = 4.05 × 10−2 M−1 s−1 for 5. The k
abstr/H values obtained for 3, 4, and 5 are similar to each other, and are by about one order of magnitude higher than that for 2. From these results, it is suggested that the prooxidant effect of α-tocopherol in edible oils, fats, and low-density lipoproteins
may be induced by the above hydrogen abstraction reaction. 相似文献
13.
Chia seeds as a source of natural lipid antioxidants 总被引:8,自引:0,他引:8
M. Silvia Taga E. E. Miller D. E. Pratt 《Journal of the American Oil Chemists' Society》1984,61(5):928-931
Chia (Salvia sp) seeds were investigated as a source of natural lipid antioxidants. Methanolic and aqueous extracts of defatted chia seeds
possessed potent antioxidant activity. Analysis of 2 batches of chia-seed oils demonstrated marked difference in the fatty
acid composition of the oils. In both batches, the oils had high concentrations of polyunsaturated fatty acids. The major
antioxidant activity in the nonhydrolyzed extract was caused by flavonol glycosides, chlorogenic acid (7.1 × 10−4 mol/kg of seed) and caffeic acid (6.6 × 10−3 m/kg). Major antioxidants of the hydrolyzed extracts were flavonol aglycones/kaempferol (1.1 × 10−3 m/kg), quercetin (2.0 × 10−4 m/kg) and myricetin (3.1 × 10−3 m/kg); and caffeic acid (1.35 × 10−2 m/kg). Two methods were used to measure antioxidant activities. Both were based on measuring bleaching ofβ-carotene in the coupled oxidation ofβ-carotene and linoleic acid in the presence of added antioxidants. 相似文献
14.
Wei-Jun Liu Guo-Xuan Xiong Dong-Hai Zeng 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(1):97-103
Three ferrocenyl-Schiff base monomers were synthesized by the condensation of ferrocenecarboxaldehyde and phenylenediamine
under neutral conditions, and then used to produce copolymer materials with terephthaloyl chloride monomer by the Friedel–Crafts
method. The model compound and copolymers of three novel poly(ferrocenyl-Schiff bases) and their charge transfer complexes
with iodine were successful obtained and their structures were characterized by 1H-NMR, infrared, and ultraviolet spectra. The effect of degree of iodine doping on their structures was studied. It appears
that poly-p-bis(ferrocenyl-Schiff base) can be doped to a higher iodine level than the other two prepared materials. Electrical measurement
results showed that the conductivity can be increased several orders of magnitude after doping with iodine. The maximum conductivity
at room temperature is 3.17 × 10−4 S cm−1 indicating that the conducting polymer has potential as a semiconductor material. 相似文献
15.
Pabyton G. Cadena Eric C. Oliveira Alberto N. Araújo Maria C. B. S. M. Montenegro Maria C. B. Pimentel José L. Lima Filho Valdinete L. Silva 《Lipids》2009,44(11):1063-1070
An expeditious colorimetric methodology for the determination of the deoxycholic acid (DCA) and of the ursodeoxycholic acid
(UDCA) in pharmaceutical formulations is reported. The method is based on their competitive complexation reaction with a color
indicator to form β-cyclodextrin-inclusion complexes. Several pH color indicators were tested, but phenolphthalein (PHP) showed
the best interaction with the β-cyclodextrin (β-CD) with an inclusion yield higher than 95%. The best concentrations of β-cyclodextrin
to form inclusion complexes were 1.24 × 10−3 and 6.2 × 10−4 M at pH 9.5 and 10.5. Statistical analysis of the results showed that the pH had a significant effect on the DCA determination
and that high β-CD-PHP inclusion complex concentrations had a significant negative effect on the UDCA determination (p < 0.05). The limit of detection and limit of quantification were 3.94 × 10−5 and 1.31 × 10−4 M for DCA (range: 6.1 × 10−6–3.13 × 10−3 M), 4.08 × 10−5 and 1.36 × 10−4 M for UDCA (range: 6.05 × 10−6–3.88 × 10−4 M). This simple and cheap method showed high stability and feasible instrumentation. 相似文献
16.
Yu. V. Pokonova 《Solid Fuel Chemistry》2010,44(6):428-430
Polymer materials with cohesion strengths from 2.9 to 5.4 MPa and adhesion to steel 3 from 2.6 to 3.1 MPa were prepared based
on compositions of shale phenols. The specific elongation varied from 75 to 125%. In the use of compositions for the immobilization
of industrial wastes, the leachability of strontium and cesium was 1 × 10−10 and 1 × 10−12 cm2/s, respectively, whereas the leachability of cobalt and ruthenium was 1 × 10−13 cm2/s, which is several orders of magnitude lower than the leachability of 1 × 10−8 cm2/s from Portland cement. 相似文献
17.
Demokritos Tsoukatos Constantinos A. Demopoulos Alexandros D. Tselepis Michael C. Moschidis Andreas Donos Angelos Evangelou Jaques Benveniste 《Lipids》1993,28(12):1119-1124
Evidence is presented that cardiolipin, a naturally occurring phospholipid, inhibits the aggregatory effect of platelet-activating
factor (paf) on rabbit plateletsin vitro. Bovine heart cardiolipin was shown to inhibit the aggregation of washed rabbit platelets induced by 1×10−10 M and 2×10−10 M paf with IC50 values (doses for half-maximal inhibition) of 8.4±0.8×10−7 M and 2.6±0.6×10−6 M, respectively. Phosphonocardiolipin was also able to inhibit platelet aggregation induced by 1× 10−10 M paf with an IC50 value of 3±1×10−7M. Both compounds, in concentrations up to 1×10−5 M, were unable to aggregate washed rabbit platelets and failed to inhibit the aggregation induced by 0.9 and 1.8 μM adenosine
diphosphate or 0.2–1.0 μM arrchidonic acid. By contrast, the acetylated derivative of cardiolipin exerted an aggregatory effect
on aspirin-treated rabbit platelets in the presence of creatine phosphate/creatine phosphokinase. This aggregation was inhibited
by the specific paf antagonists BN 52021 and WEB 2086. Also, platelets treated with acetyl-cardiolipin were insensitive to
the aggregatory effect of paf. Phosphatidic acid, phosphatidylglycerol,bis(dipalmitoylglycero)phosphate and their phosphono analogues were totally inactive. Similar data were obtained when platelet-rich
plasma was used instead of washed rabbit platelets. Our results support the hypothesis that the effect of cardiolipin is mediated
through specific paf receptors that act on the rabbit platelet membrane. 相似文献
18.
The kinetic model of asymmetric reduction of 3-oxo-3-phenylpropionic acid ethyl ester using Saccharomyces cerevisiae CGMCC No.2266 with 10% glucose as co-substrate to realize the regeneration of NADPH was established. The effect factors on
reduction, the type and the content of co-substrate and coenzyme, and the changes of the substrate and product content vs.
time during the reaction process were investigated. The results indicate that 10% glucose can increase the reaction conversion
from 23.0% to 98.4% and NADPH is reducer. The reduction process conforms with sequence mechanisms. The model parameters are
as follows: v
m
=5.0×10−4 mol·L−1·h−1, k1=1.5×10−6 mol·L−1·h−1, k2=3.0×10−3 mol·L−1·h−1. The kinetic model is in good agreement with the experimental data. 相似文献
19.
John E. McGhee Robert Silmaim E. B. Bagley 《Journal of the American Oil Chemists' Society》1978,55(2):244-247
Soybean products including soy milk can provide needed protein for human consumption. Soybean flour contains raffinose and
stachyose considered responsible for flatulence often associated with soy products. A partially purified preparation of α-galactosidase
and invertase, prepared fromAspergillus awamori NRRL 4869 cultured on wheat bran, hydrolyzes the oligosaccharides of soy milk. The α-galactosidase exhibited its maximum
activity at pH 5.0 and was stable in that pH range. The optimum temperature was 50 C; however, 8% of α-galactosidase activity
was lost after 15 min at 55 C., and complete inactivation was observed after 14 min at 70 C. Parachloromercuribenzoate, AgNO3, HgCl2, and iodine exhibited strong inhibitory effects on the enzymes. Km values of the α-galactosidase with melibiose and raffinose
as substrates were 3.0 and 3.6 × 10−2 M, respectively, and the molecular weights of both enzymes were estimated to be about 130,000 on the basis of Sephadex and
sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. 相似文献
20.
The electrooxidation of d-penicillamine (d-PA) was studied in the presence of ferrocyanide as a homogeneous mediator at the surface of a carbon paste electrode in aqueous
media using cyclic voltammetry (CV) and chronoamperometry. Under optimum pH in CV the oxidation of d-PA occurs at a potential about 380 mV less positive than that in the absence of ferrocyanide. The catalytic oxidation peak
current was dependent on the d-PA concentration and a linear calibration curve was obtained in the ranges 4.0 × 10−5–2.0 × 10−3 M and 8.0 × 10−6–1.8 × 10−4 M of d-PA with CV and differential pulse voltammetry (DPV) methods, respectively. The detection limits (3σ) were determined as 1.9 × 10−5 and 3.2 × 10−6 M by CV and DPV methods. This method was also used for the determination of d-PA in pharmaceutical preparations by the standard addition method. 相似文献