Rossby waves with linear topography in barotropic fluids

Rossby waves are the most important waves in the atmosphere and ocean, and are parts of a large-scale system in fluid. The theory and observation show that, they satisfy quasi-geostrophic and quasi-static equilibrium approximations. In this paper, solitary Rossby waves induced by linear topography in barotropic fluids with a shear flow are studied. In order to simplify the problem, the topography is taken as a linear function of latitude variable y, then employing a weakly nonlinear method and a perturbation method, a KdV (Korteweg-de Vries) equation describing evolution of the amplitude of solitary Rossby waves induced by linear topography is derived. The results show that the variation of linear topography can induce the solitary Rossby waves in barotropic fluids with a shear flow, and extend the classical geophysical theory of fluid dynamics.

An efficient combination of supercritical fluid extraction and high-speed counter-current chromatography to extract and purify homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler

Supercritical fluid extraction (SFE) was used to extract homoisoflavonoids from Ophiopogon japonicus (Thunb.) Ker-Gawler. The optimization of parameters was carried out using an orthogonal test L-9 (3)(4) including pressure, temperature, dynamic extraction time and the amount of modifier. The process was then scaled up by 100 times with a preparative SFE system under the optimized conditions of 25 MPa, 55 degrees C, 4.0 h and 25% methanol as a modifier. Then crude extracts were separated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/ACN/water (1.8:1.0:1.0:1.2:1.0 v/v). There three homoisoflavonoidal compounds including methylophiopogonanone A 6-aldehydo-isoophiopogonone A, and 6-formyl-isoophiopogonanone A, were successfully isolated and purified in one step. The collected fractions were analyzed by HPLC. In each operation, 140 mg crude extracts was separated and yielded 15.3 mg of methylophiopogonanone A (96.9% purity), 4.1 mg of 6-aldehydo-isoophiopogonone A (98.3% purity) and 13.5 mg of 6-formyl-isoophiopogonanone A (97.3% purity) respectively. The chemical structure of the three homoisoflavonoids are identified by means of ESI-MS and NMR analysis.

Extraction of Nitraria tangutorum seed oil by supercritical carbon dioxide and determination of free fatty acids by HPLC/APC/IMS with fluorescence detection

The seed oil from Nitraria tangutorum samples was obtained by supercritical carbon dioxide extraction methods. The extraction parameters for this methodology, including pressure, temperature, particle size and extraction time, were optimized. The free fatty acids in the seed oil were separated with a pre-column derivation method and 1,2-benzo-3,4-dihydrocarbazole-9-ethyl-p-toluenesulfonate (BDETS) as a labeling regent, followed by high-performance liquid chromatography (HPLC) with fluorescence detection. The target compounds were identified by mass spectrometry with atmospheric pressure chemical ionization (APCI in positive-ion mode). HPLC analysis shows that the main compositions of the seed oil samples were free fatty acids (FFAs) in high to low concentrations as follows: linoleic acid, oleic acid, hexadecanoic acid and octadecanoic acid. The assay detection limits (at signal-to-noise of 3:1) were 3.378-6.572 nmol/L. Excellent linear responses were observed, with correlation coefficients greater than 0.999. The facile BDETS derivatization coupled with mass spectrometry detection allowed the development of a highly sensitive method for analyzing free fatty acids in seed oil by supercritical CO2 extraction. The established method is highly efficient for seed oil extraction and extremely sensitive for fatty acid profile determination. (C) 2007 Elsevier B.V. All rights reserved.

Mantle-derived gaseous components in ore-forming fluids of the Xiangshan uranium

The Xiangshan U deposit, the largest hydrothermal U deposit in China, is hosted in late Jurassic felsic volcanic rocks although the U mineralization post dates the volcanics by at least 20 Ma. The mineralization coincides with intrusion of local mantle-derived mafic dykes formed during Cretaceous crustal extension in South China. Ore-forming fluids are rich in CO2, and U in the fluid is thought to have been dissolved in the form of UO2 (CO3)22− and UO2 (CO3) 34− complexes. This paper provides He and Ar isotope data of fluid inclusions in pyrites and C isotope data of calcites associated with U mineralization (pitchblende) in the Xiangshan U deposit. He isotopic compositions range between 0.1 and 2.0Ra (where Ra is the 3He/4He ratio of air=1.39×10−6) and correlates with 40Ar/36Ar; although there is potential for significant 3He production via 6Li(n,α)3H(β)3He reactions in a U deposit (due to abundant neutrons), nucleogenic production cannot account for either the 3He concentration in these fluids, nor the correlations between He and Ar isotopic compositions. It is more likely that the high 3He/4He ratios represent trapped mantle-derived gases. A mantle origin for the volatiles of Xiangshan is consistent with the δ13C values of calcites, which vary from −3.5‰ to −7.7‰, overlapping the range of mantle CO2. The He, Ar and CO2 characteristics of the ore-forming fluids responsible for the deposit are consistent with mixing between 3He- and CO2-rich mantle-derived fluids and CO2-poor meteoric fluids. These fluids were likely produced during Cretaceous extension and dyke intrusion which permitted mantle-derived CO2 to migrate upward and remobilize U from the acid volcanic source rocks, resulting in the formation of the U deposit. Subsequent decay of U within the fluid inclusions has reduced the 3He/4He ratio, and variations in U/3He result in the range in 3He/4He observed with U/3He ratios in the range 5–17×103 likely corresponding to U concentrations in the fluids b0.2 ppm.

超临界溶液快速膨胀技术制备药物微细颗粒研究

本文主要研究了超临界溶液快速膨胀法（Rapid Expansi Qnofsu Percritical of Solution，RESs）制备微细颗粒装置的建立，并在此装置上考查了实现、布洛芬、黄体酮微细化处理的RESS过程工艺参数。RESS技术是超临界流体领域的一项新兴技术。其特点是借助于超．临界流体（Supercritial Fluids，SCF）的溶解性随其密度变化的关系，利用压力的改变，迅速地减小scF中溶质的溶解度，在极短的时间内在体系中造成极大的过饱和度和巨大扰动，形成微细而均一的溶质颗粒。在操作中可避免高温分解，还可有效避免副反应及有机物污染等问题。因此RESS法是一种安全、卫生的制备微细颗粒技术。我们根据RESS技术原理，查阅大量有关RESS过程的文献报道，利用原有超临界萃取装置的溶剂供应系统和萃取釜，又自行建立了包括预膨胀段、喷头、膨胀室、流量计以及附属于它们的控制、调节元件在内的膨胀收集单元：，构成了一套完整的RESS装置。许多药物的药效与其药物颗粒大小关系密切，随着颗粒尺寸的减小，它在体内的溶解和吸收速率提高。因此我们在本研究中选择两种药物-布洛芬、黄体酮进行微细化处理。布洛芬是一种重要的消炎镇痛药，我们首先在此装置上进行布洛芬的RESS过程研究，考察了操作条件对布洛芬微细颗粒粒径、比表面积、颗粒形态的影响。实验结果表明，利用此装置完全可以实现布洛芬的微细化处理。实验中还发现用多孔金属烧结板做喷嘴时，喷出产率特别大，这一特点为RESS法的工业化提供了重要可能性。黄体酮是一种重要的昌体类激素药物，它同时又是合成其它激素类药物的关键中间体。本研究也研究了黄体酮在此装置上实现RESS过程得到微细颗粒的可行性。研究结果表明：此装置同样适用于黄体酮的微细化处理。