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海洋微藻中EPA和DHA的超临界CO2提取方法研究 总被引：1，自引：0，他引：1
用超临界CO_2萃取海洋微藻中的EPA和DHA,选用乙酸乙酯为改性剂,通过正交试验确定了工作压力、温度、CO_2消耗量和改性剂添加量等工艺条件的最优化组合,对日本小球藻Chlorellahiralaii、钝顶螺旋藻Spirulinaplatensis和亚心形扁藻Platymonassubcordiformis进行提取试验,并与直接酯化法、Bligh－Dyer法、索氏抽提法和乙醇－乙烷法等溶剂法作对比。以提取效率最高的直接酯化法为基础,超临界萃取法对日本小球藻中ω－3脂肪酸二十碳五烯酸（EPA）的提取率为92．1％,二十二碳六烯酸（DHA）为89．4％,对钝顶螺旋藻和亚心形扁藻的提取率也达到90％左右,高于其他溶剂法,产物中EPA和DHA的纯度亦优于溶剂法。 相似文献
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设计4因子5水平的正交实验方案[采用正交表L25（5＾6）],通过确定加速溶剂萃取法（ASE）处理的最优化条件,包括萃取溶剂、萃取温度、萃取时间和萃取循环次数,达到快速萃取微藻油脂并且萃取量高的效果．结果表明,除循环次数外,其他萃取条件因子均能显著影响油脂萃取量（P〈0．035）．在萃取溶剂为无水乙醇或丙酮、温度为175℃、萃取时间为16min、循环次数为3次的最优处理条件下,微藻油脂萃取量最高（19．20％～21．36％）．与常规的索氏萃取法相比,萃取量可提高39．08％～47．09％．采用ASE法在最优化条件下萃取微藻油脂可以达到良好效果． 相似文献
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《海洋湖沼通报》2019,(5)
采用大容量二氧化碳超临界流体萃取设备对裂殖壶菌OUC168菌粉进行油脂萃取,并以四种油料作物黑芝麻、大豆、花生、核桃进行比较,通过气相色谱技术检测了萃取物中的脂肪酸组成及含量,并比较和分析了不同萃取条件下超临界流体对不同脂肪酸的萃取效果。结果表明,四种油料作物中的脂肪酸均以16-18C为主,裂殖壶菌中含有丰富的长链脂肪酸DHA(22C:6,44.34%),是非常好的不饱和脂肪酸来源。二氧化碳超临界流体萃取技术可以有效萃取四种油料作物中的脂肪酸,萃取率均在75%以上。对于裂殖壶菌中脂肪酸的萃取,在萃取温度30-40℃,萃取压力30MPa,分离温度35-55℃条件下,长链脂肪酸的萃取率总体低于短链脂肪酸;同种脂肪酸在萃取温度为30℃时的萃取率高于40℃时的萃取率。在萃取温度30℃,萃取压力30MPa,分离温度55℃,分离压力8～10MPa,CO_2流速14L/h的条件下,二氧化碳超临界流体萃取裂殖壶菌总脂肪酸的萃取率为56.03%,DHA萃取率为22.16%。 相似文献
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讨论了不同温度的有机溶剂分级提取对鳀鱼鱼油得率、脂肪酸组成及EPA、DHA含量变化的影响。经15℃干法分级提取的液态鳀鱼鱼油,在设定的4种温度下,液态鳀鱼鱼油得率均随溶剂量的增加而提高;在相同溶剂量的情况下,随着分级提取温度的降低,液态鳀鱼鱼油得率呈下降的趋势。有机溶剂分级提取对14碳短碳链的饱和与不饱和脂肪酸及16碳、18碳的饱和脂肪酸的脱除效果是明显的,但对脱除20碳、22碳的长碳链饱和脂肪酸的效果不明显。在4种试验温度下,EPA和DHA的总量分别为29.88%、31.74%、35.27%和41.80%,高出美国阿拉斯佳深海鱼油对应总量(28.76%)的1.12%～13.04%。 相似文献
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温度对四种产油微藻生长和油脂特性的影响 总被引：1，自引：0，他引：1
本文采用气相质谱联用技术对三株海水微藻—三角褐指藻(Phaeodactylum tricornutum,CCMM2012)、小球藻(Chlorella vulgaris,CCMM4004)、微拟球藻(Nannochloropsis sp.,CCMM6004),和一株淡水微藻—栅藻(Scenedesmus quadricauda,CCMM4002)在不同温度下的生长及油脂变化规律进行研究。结果表明:三角褐指藻、小球藻和栅藻在20℃下的油脂产率最大,分别为2.94、5.79和5.83mg/L/d,它们在20℃的培养条件下比较适合应用于生物能源开发;而微拟球藻在25℃下油脂产率最大,达6.45mg/L/d,因此此温度下更适合用于生物能源开发。三角褐指藻在15℃条件下DHA和EPA含量最多,为16.47%,而微拟球藻在25℃下DHA和EPA最多,为22.74%;因此三角褐指藻和微拟球藻在15℃和25℃下均比较适合应用于多不饱和脂肪酸的开发,而小球藻和栅藻的EPA和DHA含量在三个温度下普遍较少,不适合用于多不饱和脂肪酸的开发。 相似文献
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以坛紫菜（Porphyra haitanensis）为实验材料,采用盐酸水解法和浸提法,以日立L-8900型高速全自动氨基酸分析仪为测定仪器,分别研究了坛紫菜总氨基酸（TAA）和游离氨基酸（FAA）在提取过程中各条件的不同水平对提取结果的影响.实验结果表明：（1）利用正交设计L9（34）对影响TAA提取的4个条件（藻体质量、稀释倍数、干燥温度、空白值）在3个水平上进行优化实验,藻体质量、稀释倍数对测定结果影响显著,干燥温度影响不显著;通过实验筛选出各条件的最佳水平为：藻体质量为0.050 0g,稀释3倍,干燥温度为60℃.（2）利用正交设计L16（45）对影响FAA测定的5个条件（藻体质量、提取液、提取温度、提取时间、空白值）在4个水平上进行优化实验,结果表明藻体质量、提取液、提取温度、提取时间的不同水平对测定结果均有显著影响,其中藻体质量对结果的影响最大;通过实验筛选出各条件的最佳水平为：藻体质量为0.010 0 g,提取液为去离子水,提取温度为60℃,提取时间为4 h. 相似文献
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Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
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海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans 总被引：1，自引：0，他引：1
A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level. 相似文献