Sample Duplication Method for Monte Carlo Simulation of Large Reaction-Diffusion System

The sample duplication method for the Monte Carlo simulation of large reaction-diffusion system is proposed in this paper. It is proved that the sample duplication method will effectively raise the efficiency and statistical precision of the simulation without changing the kinetic behaviour of the reaction-diffusion system and the critical condition for the bifurcation of the steady-states. The method has been applied to the simulation of spatial and time dissipative structure of Brusselator under the Dirichlet boundary condition. The results presented in this paper definitely show that the sample duplication method provides a very efficient way to sol-'e the master equation of large reaction-diffusion system. For the case of two-dimensional system, it is found that the computation time is reduced at least by a factor of two orders of magnitude compared to the algorithm reported in literature.     

IDENTIFICATION OF DYNAMIC BEHAVIOUR OF LIGHT-POTENTIAL TRANSDUCTION SYSTEM IN PHOTORECEPTOR OF CALLIPHORA ERYTHROCEPHALA USING IRS-STIMULI

The linear dynamic behaviour of the light-potential transduction system in photorceeptor of Calliphora erythrocephala has been studied through the cross-correlation method using InverseRepeat Sequences and the lineal model of phototransduction is provided. The impulse response function and frequency characteristics have been determiued in the condition of background illumination.The results suggest that the R1-6 is equipped with a gain and time constant control mechanism which depends upon the adaptation level of the system under study.It becomes evident that the IRS correlation method is powerful to quantify the dynamic characteristics of the system containing nonlinearities and will become a very popular application for the study of biological sensory systems.The visual receptor cells R1-6 in the fly are the most sensible choice for the study of the light-potential transdnction system of the eye. The input of the system is the temporarily varying light intensity applied upon the eyes of the fly and th     

Synthesis, Characterization of Mesoporous Al-Mg Composite Oxide and Catalytic Performance for Oxyethylation of Fatty Alcohol

A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate（SDS） as the template in the presence of ethylenediamine. The XRD, nitrogen adsorption-desorption and TEM studies indicate that the composite has a hexagonal framework structure and an average pore diameter of 2. 6 nm. The TG/DTA spectra indicate that the decomposition and the removal of the occluded surfactant of the sample take place in a range of 230-550 ℃. The mesoporous Al-Mg composite oxide exhibites a highly catalytic activity for the oxyethylation of fatty alcohols. Narrow-range distributed ethoxylates are formed in the presence of the mesoporous Al-Mg composite oxide catalyst. The distribution selectivity coefficient（Cx） is 24 when the mesoporous Al-Mg composite oxide was used as a catalyst for the oxyethylation of octanol and the average adduct degree of ethoxylates is 6. 4.     

COMPARISON OF GPC AND THERMAL FIELDFLOW FRACTIONATION METHODS FOR LINEAR AND STAR BRANCHED POLYSTYRENE SAMPLES

The Thermal Field-Flow Fractionation (TFFF) method was used to determine the elution volumeof a series of star branched polystyrene having different number of arms but the same arm molecularweigh and polystyrene standards with narrow distribution whose molecular weight ranged from5.0×10~4 to 8.6×10~5. Results were obtained by measuring at two temperature difference (△T=30℃and △T=50℃in THF. The same star branched samples were measured by means of GPC method.Comparison of Vr-Mrelationships obtained from TFFF and GPC showed that the displacement of V_r-M curves for star and linear polystyrene is larger than that in GPC. This difference is caused by theentirely different mechanism of separation for these two methods. As the controlling factor is hy-drodynamic volume of the polymer chain in solution for GPC, it is the diffusion coefficient of polymermolecules for TFFF. The experimental results indicate that the influence of variance of chain struc-ture on diffusion coefficient is stronger than that on the hydrodynamic volume and that TFFF tech-nique may be used as a method for characterizing branching of polymer molecules. For this pur-pose a proper theoretical model and more accurate experiments are needed.     

Sucrose as chiral selector for determining enantiomeric composition of phenylalanine by UV-vis spectroscopy and chemometrics

The determination of enantiomeric composition by partial least squares(PLS) modeling of UV-vis spectral data was investigated for samples of phenylalanine(phe) using sucrose as a chiral auxiliary.And a new data preprocess method,reference band normalization,was introduced to eliminate the spectral variations due to the changes of total concentration of phe.The determination coefficient(R~2) and the standard error of calibration set(SEC) of 13 standard samples are 0.9987 and 0.0128 respectively.The standard error of validation set(SECV) of 7 validation samples is 0.0049.The standard error of predict(SEP) of 6 blind samples for evaluating the robustness of the model is 0.0366.The regression model is robust to determine enantiomeric composition when total concentration varied.It is demonstrated that the reference band normalization is a convenient method of compensating for variations in total concentrations without knowing that in advance.     

Rapid and sensitive determination of fatty acids in edible oil by liquid chromatography-electrospray ionization tandem mass spectrometry

A sensitive and robust on-line LC/MS method was developed for quantitative determination of linoleic acid,docosahexaenoic acid and docosanoic acid from edible oil samples.The oil samples were dissolved in chloroform-isopropyl alcohol(20:80,v:v)solution and the three fatty acids were separated by HPLC with a C4 column using 10 mmol/L ammonium acetate-isopropyl alcohol-acetonitrile(20:40:40,v:v:v)mobile phase in isocratic elution.Electrospray ionization mass spectrometry with the selected ion recording monitoring was used to detect and quantify the fatty acid.The calibration curves were linear in the range of 10.00–5000 pg/mL for linoleic acid and docosanoic acid,and 1.000–500.0 pg/mL for docosahexaenoic acid.The limit of detection was 2.0 pg/mL for linoleic acid,3.0 pg/mL for docosanoic acid,and 0.20 pg/mL for docosahexaenoic acid.The results showed that the method described in this paper could be utilized for rapid determination of three fatty acids at picogram levels in edible oils.     

Advancing from unimechanism polymerization to multimechanism polymerization: binary polymerization

Polymerizations with multiple mechanisms performed simultaneously are promising but very challenging. As the key limitation,the complicated mutual influence between different mechanisms can be hardly defined and measured. Herein we establish a universal framework for the assessment of mutual influence between different mechanisms using binary polymerization for demonstration. The kinetics and thermodynamics of polymerization with two mechanisms are compared with the corresponding homopolymerization and the difference is expressed by a hybrid function. The hybrid function is composed of a hybrid parameter that describes the extent of mutual influence and a function that describes necessary conditions for mutual influence to occur. The extent of mutual influence can be calculated using kinetic and thermodynamic data without details of reaction mechanisms, for the first time providing a straightforward method to assess the mutual influence between different polymerization mechanisms.We envision that the method has potential in more complex systems with multiple mechanisms/monomers with mutual influence.     

Non－decoloured In－gel Digestion of Coomassie Blue－stained Proteins

A simplified method is presented for tryptic digestion of Coomassie brilliant blue(CBB)-stained proteins in polyacrylamide gels. Compared with conventional methods, the proposed method does not require a re-moval of the dye before digestion, and is thus faster and saves a lot of labor. The resulted digest canbe ana-lyzed by either RPLC/ESIMS or MALDI MS for identification of the protein in a conventional way. Model studies with bovine serum albumin(BSA) showed that 50 ng of the protein could be routinely identified. The simplified procedure displays a tendency to produce more incompletely cleaved peptides, which is favorable for improving the sequence coverage.     

Is the Chandler Period Stable?

The problem on the Chandler period is an unsolved one. Several authors suggested a hypothesis that the Chandler wobble is only one free period which slightly changes in time and is amplitude-dependent. In this paper, we shall examine the hypothesis more rigorous than that which has been carried yet. A new deconvolution method for Fourier transform is suggested. Using this method, the polar motion data since 1900 are analysed and the varying process of the Chandlerian period and amplitude are given. The analytical results show that the Chandler period is not stable and is indeed amplitude-dependent. The probable explanation for this phenomenon is that it might be caused by non-equilibrium response of the ocean.     

A New Extraction Spectrophotometric Method for the Determination of Phenol in Water

The product of the reaction among phenol, sodium nitroprusside and hydroxylamine hydrochloride in an alkaline solution can be extracted by chloroform in the presence of cetylpyridinium bromide(CPB), on the basis of which a new extraction spectrophotometric method for the determination of phenol in water is developed. The optimum determination wavelength is 720 nm. The molar absorptivity is 1.05×105 mol-1·L·cm-1 and the detection limit is 4.0 μg/L. For 30.0 and 60.0 μg/L standard solutions, the relative standard deviations are 4.5% and 2.2%, respectively(n=6). F values of the statistical analysis show that there is no notable difference between the proposed method and 4-AAP method. The results of the standard addition method for the natural water samples are satisfactory.     

A novel approach to identify plant parasitic nematodes using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Plant parasitic nematodes are difficult to identify because different species are morphologically similar, and this makes their control more difficult. The aim of this work was to develop a rapid, simple method to identify plant parasitic nematodes, based on analysis of protein profiles of nematodes generated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). Two methods have been used: grinding and direct analysis of intact nematodes. Both methods were standardised using the nematode Anguina tritici (wheat seed-gall nematode) as a model. Development of the approach involved optimisation of experimental parameters to generate reproducible diagnostic protein profiles for plant parasitic nematodes. With alpha-cyano-4-hydroxycinnamic acid (CHCA) as the matrix, the most effective solvent extraction was with 90% acetone. With sinapinic acid (SA) as matrix, 90% ethanol was most effective. When intact nematodes were analysed directly by mixing with the matrix solution, 40 min extraction with CHCA matrix solution generated the best protein profiles. The standardised methods were applied to analyse the seed-gall nematodes A. tritici and A. funesta and to the root-knot nematode, Meloidogyne javanica, which infects many horticultural crops. Typical protein profiles and diagnostic peaks were identified for these nematode species and for mixtures of Anguina species. The results provide 'proof-of-concept' that these nematode species can be identified by protein profiling using MALDI-TOFMS. This new approach could be extended to identify other plant and non-plant parasitic nematodes.     

食醋中C_1－C_8脂肪酸及乳酸的气相色谱分析

食醋中Ｃ１－Ｃ８脂肪酸和乳酸与适当过量的四甲基氢氧化铵作用生成季胺盐，用二甲基甲酰胺将其溶解，在室温下与过量溴乙烷完全反应而生成相应的乙酯。生成的乙酯在１０％丁二酸乙二醇聚酯（ＰＧＳ）柱上进行分离。用保留时间定性，用内标法定量。本法操作简便、快速，分离完全，对几种样品的测定结果较好     

Quantitative determination of the fatty acid composition of human serum lipids by high-performance liquid chromatography

A high-performance liquid chromatographic method for the analysis of the fatty acid composition of human serum lipids with fluorescence detection was examined. Both free and total fatty acids extracted from serum were derivatized with 9-anthryldiazomethane and were analysed using methanol-water (94.7:5.3) as mobile phase. Twelve kinds of fatty acid were detected, both in the free and total fatty acids, and were well separated. Concentrations of individual fatty acids of serum lipids were estimated from an internal standard, heptadecanoic acid. The results correlated well with those from two other quantitative analyses. These results indicate that the high-performance liquid chromatographic analysis of fatty acids is a reliable method for determining individual fatty acids of human serum lipids. The compositions of free fatty acids and total fatty acids of serum lipids were analysed and compared in 27 normal subjects, 27 diabetics, and 20 angina pectoris patients by this method.     

Analysis of fatty acids in lung tissues using gas chromatography-mass spectrometry preceded by derivatization-solid-phase microextraction with a novel fiber

In this article, a laboratory-made sol-gel derived fiber with butyl methacrylate/hydroxy-terminated silicone oil (BMA/OH-TSO) coating was first used for headspace solid-phase microextraction (HS-SPME) of medium and long chain fatty acids after derivatization and applied to the analysis of fatty acids in lung tissues by coupling to gas chromatography-mass spectrometry (GC-MS). The experimental parameters for derivatization, HS-SPME and desorption were optimized. Fatty acids in cancerous lung tissues from five patients with lung cancer were determined under the optimized conditions. Normal lung tissues from the same five patients were used as controls. This fiber showed higher extraction efficiency for fatty acids after derivatization when compared with commercial polydimethylsiloxane (PDMS) and polydimethylsiloxane-divinylbenzene (PDMS/DVB) fibers due to the three-dimensional network in the coating. The method presented in this paper showed satisfactory precision, accuracy, linearity and limits of detection (LODs). The relative standard deviation values were below 13.3% (n = 5) and the recoveries obtained ranged from 76.35% to 107.0%. The results obtained using the SPME method were also compared with those got by using liquid-liquid extraction (LLE) technique. It was found that the sensitivity could be enhanced by the SPME method. The analysis of the cancerous lung tissues and normal controls from five patients with lung cancer indicated that the main components of lung tissue were palmitic acid (C_16:0), stearic acid (C_18:0) and lignoceric acid (C_24:0). A comparison between the levels of the fatty acids in cancerous lung tissues and normal controls from the same a patient with lung cancer shows that most of the saturated fatty acids showed higher levels in cancerous lung tissues, while unsaturated fatty acids showed higher levels in normal controls on the whole.     

三烷基氧化膦中脂肪酸的气相色谱测定

报道了用气相色谱测定萃取剂三烷基氧化膦中的微量脂肪酸。用碳酸钠溶液萃洗分离三烷基氧化膦,在甲醇溶液中用四甲基氢氧化铵作为甲基化试剂,反应在裂解进样器中进行,回收率为90％－105％,误差在10％以内。     

Measurement of polyunsaturated fatty acids of myocardial lipids by high performance liquid chromatography

Summary This report describes a modified method for the separation and analysis of polyunsaturated fatty acids such as 20:4, 20:5, and 22:6, using HPLC. The results show that these fatty acids are well separated from the saturated acids. Since the unsaturated fatty acids elute earlier than saturated acids, and this method does not require the fractionation of free fatty acids using thin layer chromatography, a necessary step for the gas chromatographic analysis, the recoveries of polyunsaturated fatty acids were significantly higher as compared to those from gas chromatography. Furthermore, HPLC and gas chromatographic methods gave identical results for the acyl chain composition of phosphatidylserine. The advantages of using HPLC over gas chromatography in determining the acyl chain composition of free fatty acids and phospholipids are also discussed.     

小鼠眼球中脂肪酸的组成分析

首次对小鼠眼球中的脂肪酸组成进行了气相色谱分析。小鼠眼球中的脂肪酸经氯仿－甲醇－盐酸混合液萃取,用甲醇－氢氧化钾法甲酯化,在２５ｍ×０．２５ｍｍＰＥＧ－２０Ｍ熔融石英毛细管柱内进行分离,眼球中１２种主要脂肪酸得到了定性和定量。测试结果提示：正常小鼠眼球中饱和脂肪酸含量较高,占全部脂肪酸含量的５２．８％;不饱和脂肪酸含量较少,但以多不饱和脂肪酸居多,占全部脂肪酸含量的１８．２％,不饱和脂肪酸与饱和脂肪酸的比值为０．６。可为有关眼疾病的治疗、预防及生化方面的深入研究提供有意义的信息。     

植物油中脂肪酸不同定量方法的比较分析

比较峰面积归一化法与标准曲线法两种方法分析植物油中脂肪酸百分比含量的差异.利用气相色谱-质谱联用仪(GC-MS)检测10种市售食用植物油中的8种主要脂肪酸,峰面积归一化法和标准曲线法计算脂肪酸的百分比含量.结果表明,标准曲线法与峰面积归一化法相比,肉豆蔻酸、棕榈酸、十七烷酸、硬脂酸和棕榈油酸所占的百分比升高,而油酸、亚...     

Ultra-fast screening of free fatty acids in human plasma using ion mobility mass spectrometry

Free fatty acids are involved in many metabolic regulations in the human body. In this work, an ultra-fast screening method was developed for the analysis of free fatty acids using trapped ion mobility spectrometry coupled with mass spectrometry. Thirty-three free fatty acids possessing different unsaturation degrees and different carbon chain lengths were baseline separated and characterized within milliseconds. Saturated, monounsaturated, and polyunsaturated free fatty acids showed different linearities between collision cross-section values and m/z. The establishment of correlations between structures and collision cross-section values provided additional qualitative information and made it possible to determine free fatty acids which were out of the standards pool but possessed the confirmed linearity. The gas-phase separation made the quantitative analysis reliable and repeatable at a much lower time cost than chromatographic methods. The sensitivity was comparable to and even better than the reported results. The method was validated and applied to profiling free fatty acids in human plasma. Saturated free fatty acids abundance in the fasting state was found to be lower than that in the postprandial state, while unsaturated species abundance was found higher. The method was fast and robust with minimum sample pretreatment, so it was promising in the high-throughput screening of free fatty acids.     

A Novel Labeling Reagent of 2-(12-Benzo[b]acridin-5-(12H)-yl)-acetohydrazide for Determination of Saturated and Unsaturated Fatty Acids in Traditional Chinese Herbs by HPLC-APCI-MS

A new fluorescence labeling reagent 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) has been designed for fatty acids labeling. Eleven fatty acids containing seven saturated and four unsaturated fatty acids were used to evaluate the analytical potential of this reagent. The labeling reaction of BAAH with fatty acids was completed at 85?°C for 60?min using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl) as the condensing agent. Separation of the derivatized fatty acids was carried out on a reversed-phase Thermo Hypersil Gold C18 column (4.6?mm?×?250?mm, 5?μm) in combination with a gradient elution with a good baseline resolution. The fluorescence excitation and emission wavelengths were set at λ_ex 280 and λ_em 510?nm, respectively. The identification was carried out by the online APCI-MS in positive-ion detection mode. Linear correlation coefficients for all fatty acid derivatives were of >0.9994. Detection limits, at a signal-to-noise ratio of 3:1, were 3.89–12.5?nmol?L^?1 for the labeled fatty acids. The developed method was successfully applied to the accurate determination of fatty acids in five traditional Chinese herbs with satisfactory results.