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31.
Weighted least squares and error-in-variable statistical methods were used to minimize variations in the experimental data set obtained from literature, and were used to validate Models I and II, S h′ = 0.0015(R e 1/2 S c 1/3)2.58 and S h′ = 0.00084(R e 0.4299 S c 0.8783), respectively. Published data were used for the empirical estimation of mass transfer coefficients in separation processes in fixed bed systems using supercritical carbon dioxide extraction with low molecular diffusion. Model I gained accuracy when the Schmidt Number Sc is high (> 70) and the molecular diffusion is weak. The exponential ratio of the Re and Sc of Model II differed from the common ratio of 3:2; however, the exponents of the Sc are unique for both Models I and II. 相似文献
32.
A series of bimodal polyethylenes with different molecular weight distribution characteristics were prepared by melt blending, and the fracture behavior of these bimodal polyethylenes was studied by the method of essential work of fracture. The results show that specific essential work of fracture, we, increases obviously with the molecular weight distribution characteristic, AL/U, indicating the improvement of the resistance to crack propagation. By means of successive self-nucleation and annealing analysis, obvious variations in the crystal structures of bimodal polyethylenes with increasing AL/U have been found. That is, the crystal size and the amount of relatively thick lamellas increase with AL/U, but no large variation of crystallinities has been observed. So, the influence of AL/U is mainly on the crystal perfection, the improvement of which produces an enhancement of fracture toughness since more energy would be dissipated in the superior network structure constructed from crystalline zones and amorphous zones. 相似文献
33.
Fernanda B. R. D. Iorio Ana M. A. Liberatore Ivan H. J. Koh Choyu Otani 《臭氧:科学与工程》2016,38(4):253-260
The ozonation of vegetable oils has been studied, since the produced ointments have antibacterial and fungicidal activities. However, the ozonation of mineral oils has not been reported in the literature yet, opening an interesting field for examination. In this work, we have shown the ozonation of a commercial mineral oil (Nujol). The main goal was to produce oils containing free ozone, so that this gas could act as antimicrobial agent. It was found that in Nujol, ozone remains for at least 40 days and in the sample ozonized for 15 h its concentration was 7.5 mg mL?1. Neat Nujol showed no antimicrobial activity against the tested microorganisms, however, when ozonated it showed antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus and Escherichia coli. 相似文献
34.
Adriana Dillenburg Meinhart Tayse Ferreira Ferreira da Silveira Mateus Henrique Petrarca Leonardo Henrique Silva Maria Rosa de Moraes Cristiano Augusto Ballus Patrícia Oliveira de Souza Thais Cristina Lima de Souza Roger Wagner Helena Maria André Bolini Roy Edward Bruns Helena Teixeira Godoy 《European Journal of Lipid Science and Technology》2017,119(10)
35.
Mahtab Samadi Zurina Zainal Abidin Robiah Yunus Dayang Radiah Awang Biak Hiroyuki Yoshida Eng Hai Lok 《中国化学工程学报》2017,25(2):216-222
This study aimed to model the kinetic of hydro-distillation of Aquilaria malaccensis leaves oil in order to understand and optimize the extraction process. In addition, this study, for the first time, aimed to identify the chemical compositions of the A. malaccensis leave-oil. By assessing both first-order kinetic model and the model of simultaneous washing and diffusion, the result indicated that the model of simultaneous washing and diffusion better describes the hydro-distillation mechanism of the essential oil from A. malaccensis leaves.The optimum time, solid to liquid ratio, and the heating power for extracting the highest amount of essential oil were found to be around 3 h, 1:10(g·ml-1), and 300 W respectively. Yellow essential oil with a strong smell and a yield of 0.05 v/w was extracted by hydro-distillation Clevenger apparatus. Chemical compounds of the essential oil were analyzed using gas chromatography–mass spectroscopy(GC/MS), which resulted in identification of 42 compounds that constitute 93% of essential oil. Among the identified components,Pentadecanal(32.082%), 9-Octadecenal,(Z)(15.894%), and Tetradecanal(6.927%) were the major compounds.Considering the fact that all the identified major components possess pesticidal properties, A. malaccensis leaves can be regarded as a promising natural source for producing pesticides. 相似文献
36.
CO2超临界萃取技术提取沙田柚皮的研究 总被引:2,自引:0,他引:2
采用沙田柚皮作为实验材料 ,研究在CO2 超临界流体萃取时 ,粉碎度、温度、压力、萃取时间等条件对精油萃取率的影响 ,得到萃取沙田柚皮精油的最佳条件为 13MPa ,4 0℃ ,萃取时间 1h ,为批量生产提供了依据 相似文献
37.
Since acne vulgaris is the combined result of a bacterial infection and the inflammatory response to that infection, we examined
whether Abies koreana essential oil (AKE) possessed anti-inflammatory and antibacterial activities against skin pathogens. In this study, AKE showed
excellent antibacterial activities against drug-susceptible and -resistant Propionibacterium acnes and Staphylococcus epidermidis, which are acne-causing bacteria. In addition, AKE reduced the LPS-induced secretion of tumor necrosis factor-α (TNF-α),
interleukin-1β (IL-1β), IL-6, NO and PGE2 in RAW 264.7 cells, indicating that it has anti-inflammatory effects. Therefore, we suggest that AKE may be an attractive
candidate for promoting skin health. 相似文献
38.
Harminder Pal Singh Shalinder Kaur Sunil Mittal Daizy Rani Batish Ravinder Kumar Kohli 《Journal of chemical ecology》2009,35(2):154-162
We investigated the chemical composition and phytotoxicity of the essential oil extracted from leaves of Artemisia scoparia Waldst. et Kit. (red stem wormwood, Asteraceae). GC/GC-MS analyses revealed 33 chemical constituents representing 99.83%
of the oil. The oil, in general, was rich in monoterpenes that constitute 71.6%, with β-myrcene (29.27%) as the major constituent followed by (+)-limonene (13.3%), (Z)-β-ocimene (13.37%), and γ-terpinene (9.51%). The oil and β-myrcene were evaluated in a dose–response bioassay under laboratory conditions for phytotoxicity against three weeds—Avena fatua, Cyperus rotundus, and Phalaris minor. A significant reduction in germination, seedling growth, and dry matter accumulation was observed in the test weeds. At
the lowest treatment of 0.07 mg/ml Artemisia oil, germination was reduced by 39%, 19%, and 10.6% in C. rotundus, P. minor, and A. fatua, respectively. However, the inhibitory effect of β-myrcene was less. In general, a dose-dependent effect was observed and the growth declined with increasing concentration.
Among the three weeds, the inhibitory effect was greatest on C. rotundus, so it was selected for further studies. We explored the explanation for observed growth inhibition in terms of reactive
oxygen species (ROS: lipid peroxidation, membrane integrity, and amounts of conjugated dienes and hydrogen peroxide)-induced
oxidative stress. Exposure of C. rotundus to Artemisia oil or β-myrcene enhanced solute leakage, indicating membrane disintegration. There were increased levels of malondialdehyde and hydrogen
peroxide, indicating lipid peroxidation and induction of oxidative stress. We conclude that Artemisia oil inhibits plant root growth through generation of ROS-induced oxidative damage. 相似文献
39.
Fatty acid analysis is an important research tool, and indices derived from essential fatty acid contents serve as useful
biomarkers related to cardiovascular and other chronic disease risk. Both clinical and basic studies of essential fatty acid
composition are becoming ever larger in magnitude leading to delays while the rather laborious lipid analyses are performed.
A robotic transesterification procedure has been developed for high-throughput analysis of plasma fatty acid methyl esters.
In this approach, robots perform most steps including plasma and reagent transfer, transesterification reaction via heating
at 80 °C in open tubes with multiple reagent additions, followed by two-phase extraction and transfer of lipid extracts to
GC vials. The vials are then placed directly onto a GC autosampler carousel for robotic sample injection. An improved fast
GC method is presented in which the peaks of interest are eluted within 6 min. This method is readily scalable to prepare
and analyze 200 samples per day (1,000 samples per week) so that large clinical trials can be accommodated.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
40.
Hajar Abbasi Karamatollah Rezaei Ladan Rashidi 《Journal of the American Oil Chemists' Society》2008,85(1):83-89
In this study, essential oils from pomegranate seeds of the Malas variety from Shahreza, Iran, were extracted using hexane
and petroleum benzene applying four extraction methods: normal stirring, soxhlet, microwave irradiation, and ultrasonic irradiation.
Also, supercritical fluid extraction (SFE) using CO2 under different conditions was used for comparison. Different methods of extraction with organic solvents (normal stirring,
soxhlet, microwave irradiation, and ultrasonic irradiation) showed significant differences in the extraction yields. However,
no differences were found when a given method (e.g., microwave irradiation) was applied using different organic solvents.
On the other hand, different extraction conditions from the various runs of SFE resulted in different extraction yields, all
of which were lower than those of the other extraction methods using organic solvents. No significant differences were observed
in the fatty acid compositions of the extracted oils using organic solvents. However, the fatty acid compositions of the oils
extracted under different conditions of the SFE system indicated significant differences among several fatty acids including
unsaturated fatty acids. 相似文献