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81.
Extraction of nutraceuticals from milk thistle 总被引:1,自引:0,他引:1
Sunny N. Wallace Danielle Julie Carrier Edgar C. Clausen 《Applied biochemistry and biotechnology》2003,108(1-3):881-889
Milk thistle contains compounds that display hepatoxic protection properties. We examined the batch extraction of silymarin
compounds from milk thistle seed meal in 50, 70, 85, and 100°C water as a function of time. After 210 min of extraction at
100°C, the yield of taxifolin was 1.2 mg/g of seed, a 6.2-fold increase over the results obtained in a Soxhlet extraction
with ethanol on pretreated (defatted) seeds. Similarly, the yield of silychristin was 5.0 mg/g of seed, a 3.8-fold increase.
The yields of silybinin A and silybinin B were 1.8 and 3.3 mg/g of seed, respectively, or roughly 30% of the Soxhlet yield.
The ratios of the extracted compounds, and particularly the ratios at long extraction times, showed that the more polar compounds
(taxifolin and silychristin) were preferentially extracted at 85°C, while the less polar silybinin was favored at 100°C. 相似文献
82.
83.
E. Clausen E. S. Lahaniatis M. Bahadir und D. Bieniek 《Fresenius' Journal of Analytical Chemistry》1987,327(3-4):297-300
Summary Several plastics (polyester and hardened epoxideresins) with flame retardants as additives were tested for the formation of brominated dibenzofurans and dibenzodioxins under temperatures from 400 °C to 800 °C under aerobic conditions. 2,3,7,8-Tetrabromodibenzodioxin was not formed at a detection limit of 10 ppm (g·g–1). At 400 °C, polymers containing decabromodiphenylether and antimony trioxide as flame retardant yield up to 4,000 ppm tetrabromodibenzofurans (TBrDF), besides other brominated dibenzofurans.In contrast, formation of polybrominated dibenzofurans does not occur with polymers containing decabromodiphenylether without antimony trioxide. 2,3,7,8-Tetrabromodibenzufuran could not be found at a detection limit of 20 ppm. Under the given thermolytical conditions, polymers with brominated flame retardants such as tetrabromobisphenol-A, polytribromostyrene, hydroxyethylated tetrabromobenzimidazolone, poly(pentabromobenzyl)acrylate or N,N-ethylene-bis-tetrabromophthalimide snowed no tendency to form polybrominated dibenzodioxins or dibenzofurans, even in the presence of antimony trioxide. 相似文献
84.
V. Tarigopula O.S. Hopperstad M. Langseth A.H. Clausen F. Hild 《International Journal of Solids and Structures》2008,45(2):601-619
Tensile tests were conducted on dual-phase high-strength steel in a Split-Hopkinson Tension Bar at a strain-rate in the range of 150–600/s and in a servo-hydraulic testing machine at a strain-rate between 10?3 and 100/s. A novel specimen design was utilized for the Hopkinson bar tests of this sheet material. Digital image correlation was used together with high-speed photography to study strain localisation in the tensile specimens at high rates of strain. By using digital image correlation, it is possible to obtain in-plane displacement and strain fields during non-uniform deformation of the gauge section, and accordingly the strains associated with diffuse and localised necking may be determined. The full-field measurements in high strain-rate tests reveal that strain localisation started even before the maximum load was attained in the specimen. An elasto-viscoplastic constitutive model is used to predict the observed stress–strain behaviour and strain localisation for the dual-phase steel. Numerical simulations of dynamic tensile tests were performed using the non-linear explicit FE code LS-DYNA. Simulations were done with shell (plane stress) and brick elements. Good correlation between experiments and numerical predictions was achieved, in terms of engineering stress–strain behaviour, deformed geometry and strain fields. However, mesh density plays a role in the localisation of deformation in numerical simulations, particularly for the shell element analysis. 相似文献
85.
M. Dülk ST. Fischer M. Bitter M. Caraccia W. Vogt E. Gini H. Melchior W. Hunziker A. Buxens H.N. Poulsen A.T. Clausen 《Optical and Quantum Electronics》2001,33(7-10):899-906
A monolithically integrated and fully packaged Mach–Zehnder interferometer with semiconductor optical amplifiers (MZI-SOA) is demonstrated as polarisation-independent high-speed demultiplexer for up to 160 Gbit/s optical time division multiplexed (OTDM) data streams. 相似文献
86.
U. Pedersen B. Yde T. Andersen M. Thorsen K. Clausen S.-O. Lawesson 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):381-384
Abstract 2, 4-Bis(4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane 2, 4-disulfide, LR, is easily prepared by refluxing P4S10 in anisole for two hours produces the title compound in high yield. 相似文献
87.
A Glycan Array‐Based Assay for the Identification and Characterization of Plant Glycosyltransferases
Colin Ruprecht Max P. Bartetzko Deborah Senf Anna Lakhina Peter J. Smith Maria J. Soto Hyunil Oh Jeong‐Yeh Yang Digantkumar Chapla Daniel Varon Silva Mads H. Clausen Michael G. Hahn Kelley W. Moremen Breeanna R. Urbanowicz Fabian Pfrengle 《Angewandte Chemie (International ed. in English)》2020,59(30):12493-12498
Growing plants with modified cell wall compositions is a promising strategy to improve resistance to pathogens, increase biomass digestibility, and tune other important properties. In order to alter biomass architecture, a detailed knowledge of cell wall structure and biosynthesis is a prerequisite. We report here a glycan array‐based assay for the high‐throughput identification and characterization of plant cell wall biosynthetic glycosyltransferases (GTs). We demonstrate that different heterologously expressed galactosyl‐, fucosyl‐, and xylosyltransferases can transfer azido‐functionalized sugar nucleotide donors to selected synthetic plant cell wall oligosaccharides on the array and that the transferred monosaccharides can be visualized “on chip” by a 1,3‐dipolar cycloaddition reaction with an alkynyl‐modified dye. The opportunity to simultaneously screen thousands of combinations of putative GTs, nucleotide sugar donors, and oligosaccharide acceptors will dramatically accelerate plant cell wall biosynthesis research. 相似文献
88.
89.
Sørensen J Clausen HF Poulsen RD Overgaard J Schiøtt B 《The journal of physical chemistry. A》2007,111(2):345-351
The environmental influence on the electronic character of two O-H...O hydrogen bonds in a beta-diketone, 2-acetyl-1,8-dihydroxy-3,6-dimethylnaphthalene, is studied by low-temperature synchrotron X-ray diffraction and high-level density functional theory (DFT) calculations. It is revealed that one of the hydrogen bonds is very strong, yet partial localization is found. This result is analyzed by atoms in molecules (AIM) theory and applying the source function. Model compounds, with less steric strain, reveal that the strong hydrogen bond is not merely a result of steric compression. 相似文献
90.
Outgassing minerals at elevated temperatures prior to BET measurements can lead to phase changes, especially in the case of amorphous and poorly crystalline materials. In order to evaluate the applicability of the BET method when low outgassing temperatures are required, selected aquifer minerals were outgassed at different temperatures and for different times. The studied minerals are 2-line ferrihydrite, goethite, lepidocrocite, quartz, calcite, alpha-alumina, and kaolinite. The results demonstrate that measured specific surface areas of iron oxides are strongly dependent on outgassing conditions because the surface area increased by 170% with increasing temperature. In the poorly crystalline minerals, phase changes caused by heating were observed at temperatures lower than 100 degrees C. Therefore low outgassing temperatures are preferable for minimizing phase changes. As demonstrated in this study, stable BET values can be obtained by increasing the outgassing time without heating iron oxides. For quartz, calcite, alpha-alumina, and kaolinite, stable BET values were obtained after outgassing the minerals at 100 to 250 degrees C for 2 h. However, outgassing these minerals at room temperature (20 degrees C) only resulted in minor errors, implying that aquifer sediments containing poorly crystalline materials can be outgassed at low temperatures if the outgassing time is increased. Scanning electron microscopy of the studied minerals demonstrated that the particle size as calculated from BET data compares well with particle size observed by scanning electron microscopy images. Copyright 2000 Academic Press. 相似文献