Comparison of different methods for variable selection

In chemistry for chemical analysis of a multi-component sample or quantitative structure-activity/property relationship (QSAR/QSPR) studies, variable selection is a key step. In this study, comparisons between different methods were performed. These methods include three classical methods such as forward selection, backward elimination and stepwise regression; orthogonal descriptors; leaps-and-bounds regression and genetic algorithm. Thirty-five nitrobenzenes were taken as the data set. From these structures quantum chemical parameters, topological indices and indicator variable were extracted as the descriptors for the comparisons of variable selections. The interesting results have been obtained. (C) 2001 Elsevier Science B.V. All rights reserved.

Theoretical study on the mechanisms of some elementary reactions catalyzed by modified carbonyl cobalt

All structural geometries of intermediates, transition states and product are, optimized at HF/ LANL2DZ level under the effective core potential approximation. The potential energy profile for some elementary reactions of hydroformylation catalyzed by Co-2(CO)(6)(PH3)(2), consisting of carbonyl insertion, H-2 oxidative addition and aldehyde reductive elimination, are calculated, The transition states are further confirmed by having one and only one imaginary vibrational frequency, The activation energies of carbonyl insertion, H-2 oxidative addition and aldehyde reductive elimination are 54, 02, 134, 02 and 43. 44 kJ/mol, respectively.

Variable selection by orthogonal descriptors and prediction of R-f value of phenol and aniline derivatives

Orthogonal descriptors is a viable method for variable selection, but this method strongly depend on the orthogonalisation ordering of the descriptors. In this paper, we compared the different methods used for order the descriptors. It showed that better results could be achieved with the use of backward elimination ordering. We predicted R-f value of phenol and aniline derivatives by this method, and compared it with classical algorithms such as forward selection, backward elimination, and stepwise procedure. Some interesting hints were obtained.

Cobalt(II)hexacyanoferrate film modified glassy carbon electrode for construction of a glucose biosensor

An amperometric glucose biosensor was constructed based on a glassy carbon electrode modified with a Cobalt(II)hexacyanoferrate film which catalyzes electroreduction of hydrogen peroxide. Gelatin was used as immobilization matrix. Interference could be effectively eliminated by the combination of low detection potential with a Nafion coating. A low applied potential can avoid oxidation of interferences such as ascorbic acid, uric acid, p-acetyl-aminophenol, etc.. Nafion coating prevents interferences from access to the electrode surface by electrostatic repulsion. A wide linear range of detection was obtained. Analytical performance parameters are given and kinetic analysis discussed.

Structure of [C8H7](+) and intramolecular proton transfer reactions in 3-phenyl-1-butyn-3-ol by MS/MS technique

The electron impact mass spectrum (EIMS) of 3-phenyl-1-butyn-3-ol was reported in this paper. Collision-induced dissociation (CID) was used to study the gas phase ion structure of [C8H7](+) formed by the fragmentation of ionized 3-phenyl-1-butyn-3-ol, and that it has the same structure as m/z 103 ions generated by cinnamic acid and alpha-methylstyrene. Deuterium labelling, metastable ion (MI) and CID experimental results indicate the formation of m/z 103 ion resulting from molecular ion of 3-phenyl-1-butyn-3-ol, which is a stepwise procedure via twice proton transfers, rather than concerted process during the successive elimination of methyl radical and neutral carbon monoxide accompanying hydrogen transfer. Moreover, in order to rationalized these fragmentation processes, the bimolecular proton bound complex between benzyne and acetylene intermediate has been proposed.

Ion/neutral complex-mediated reactions generated from some ionized tetrahydroimidazole-substituted methylene beta-diketones

The dissociation of gaseous metastable ions of m/z 153 and the formation of ions of m/z 139 from the unimolecular fragmentations of ionized tetrahydroimidazole-substituted methylene beta-diketones were examined by tandem mass spectrometry. In addition, some other fragments accompanying the elimination of either an H2O molecule or an CHO. radical were also observed in the collision-induced dissociation spectra of molecular ions of the compounds bearing an aromatic ring. Collision-induced dissociation and isotopic labeling showed that these processes may involve reactions of intermediate ion/neutral complexes and multistep rearrangements. The corresponding mechanisms are discussed. (C) 1997 by John Wiley & Sons, Ltd.

SYNTHESES AND CHARACTERIZATION OF [(MU-CF3CO2)(2)LN(MU-CF3CHO2)ALR(2)CENTER-DOT-2THF](2) AND THEIR CATALYTIC ACTIVITIES FOR POLYMERIZATION OF SOME POLAR MONOMERS

Three new bimetallic complexes were synthesized and crystalized by reactions of (CF3CO2)(3)Ln With R(1) AlR(2)(Ln=Nd and Y, R(1)=H, R=i-C4H9; Ln=Eu, R=R(1)=C2H5) in tetrahydrofuran solution, and their crystal structures were determined using a X-ray diffraction method. The structures and the questions on valence state and noncoplanarity in the structures were confirmed and cracked by means of H-1 NMR and C-13 NMR spectra, especially by C-13-H-1 COSY 2D NMR technique. A general formula of molecules of the three rare earth complexes was defined as follows: [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AlR(2) . 2THF](2) A mechanism on the formation of the new complexes was also proposed through the following five steps: alkylating, beta-elimination (or hydrogenation), hydrogen transfer, linkage and association. Both Y-Al and Eu-Al complexes function as a catalyst in polymerization of MMA and ECH. The polymer obtained from the first monomer is mainly syndiotactic chain structure and the polymerization of the last monomer shows higher catalytic activity. The Y-Al complex also capable of ring-opening polymerization of THF in case of adding-vary small amount of ECH and a oxonium ion mechanism of THF polymerization was suggested from the analysis of THF polymer terminal.

APPLICATION OF FACTOR-ANALYSIS TO CORRECTION OF SPECTRAL OVERLAP INTERFERENCE IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

Correction of spectral overlap interference in inductively coupled plasma atomic emission spectrometry by factor analysis is attempted. For the spectral overlap of two known lines, a data matrix can be composed from one or two pure spectra and a spectrum of the mixture. The data matrix is decomposed into a spectra matrix and a concentration matrix by target transformation factor analysis. The component concentration of interest in a binary mixture is obtained from the concentration matrix and interference from the other component is eliminated. This method is applied to correcting spectral interference of yttrium on the determination of copper and aluminium: satisfactory results are obtained. This method may also be applied to correcting spectral overlap interference for more than two lines. Like other methods of correcting spectral interferences, factor analysis can only be used for additive spectral overlap. Results obtained from measurements on copper/yttrium mixtures with different white noise added show that random errors in measurement data do not significantly affect the results of the correction method.

SPECTROPHOTOMETRIC DETERMINATION OF LANTHANUM AND SUM OF OTHER LIGHT RARE-EARTHS BY FLEXIBLE TOLERANCE SIMPLEX-METHOD

The absorptivities of color elements in a mixture can be obtained by using Gauas' elimination with selection of principal element in matrix to the standards. These values can be applied to flexible tolerance simplex method to give the composition of samples. In the exprimental design and data treatment, an effort was made to minimize the errors of results according the principal of optimization. When the difference of absorptivities of color material is significant to the exprimental error, the pr...

Comparative expression analysis of transcription factor genes in the endostyle of invertebrate chordates

The endostyle of invertebrate chordates is a pharyngeal organ that is thought to be homologous with the follicular thyroid of vertebrates. Although thyroid-like features such as iodine-concentrating and peroxidase activities are located in the dorsolateral part of both ascidian and amphioxus endostyles, the structural organization and numbers of functional units are different. To estimate phylogenetic relationships of each functional zone with special reference to the evolution of the thyroid, we have investigated, in ascidian and amphioxus, the expression patterns of thyroid-related transcription factors such as TTF-2/MoxE4 and Pax2/5/8, as well as the forkhead transcription factors FoxQ1 and FoxA. Comparative gene expression analyses depicted an overall similarity between ascidians and amphioxus endostyles, while differences in expression patterns of these genes might be specifically related to the addition or elimination of a pair of glandular zones. Expressions of Ci-FoxE and BbFoxE4 suggest that the ancestral FoxE class might have been recruited for the formation of thyroid-like region in a possible common ancestor of chordates. Furthermore, coexpression of FoxE4, Pax2/5/8, and TPO in the dorsolateral part of both ascidian and amphioxus endostyles suggests that genetic basis of the thyroid function was already in place before the vertebrate lineage. (c) 2005 Wiley-Liss, Inc.

Genetic characterization of asymmetric reciprocal hybridization between the flatfishes Paralichthys olivaceus and Paralichthys dentatus

Interspecific reciprocal crosses between the two flatfishes Paralichthys olivaceus and P. dentatus yielded hybrids with different viabilities. Specifically, the hybrids of P. olivaceus female and P. dentatus male (HI) were found to be viable, while the reciprocal hybrids from P. dentatus female and P. olivaceus male (HII) were completely inviable. All the HII individuals showed morphological deformities and died before first feeding. The chromosome analysis showed that HI individuals had the same chromosome number as parents. However, two chromosomes were missing in HII offspring indicating that the latter were aneuploids. Genomic inheritance from the parents to F-1 progeny was also examined by amplified fragment length polymorphism (AFLP) analyses, and the results showed differences between reciprocal hybrids. Almost all AFLP bands (97.71%) observed in parents were passed on to HI individuals. In contrast, only 86.64% of the AFLP bands from parents were scored in HII individuals. Frequency of lost parental bands was thus significantly higher in HII than that in HI and intraspecific crosses, which was probably associated with chromosomal elimination. In addition, higher segregation distortions were found in hybrids than in controls, although these differences were not significant. The present study indicates that chromosomal elimination and loss of AFLP loci occurred in inviable HII individuals, while such genomic changes were not found in viable HI individuals. Possible implications of such difference on genomic changes for asymmetric viability in reciprocal hybrids are discussed.

中国明对虾免疫系统中抗氧化相关基因的克隆与表达分析

对虾病害在世界范围内的广泛传播，给水产养殖和沿海农村经济造成了重大损失。深入开展对虾免疫机制研究并在此基础上寻找对虾疾病防治的有效方法已成为当务之急。研究表明，当对虾等甲壳动物受到外界病原刺激时，其体内的吞噬细胞在吞噬活动中会激活磷酸己糖支路的代谢，引起呼吸爆发，产生多种活性氧分子。另外，受到病原侵染的对虾还会产生其他多种免疫反应，这些免疫反应将消耗大量的能量（ATP），产能的呼吸链会加速运转，由此也会引发大量活性氧的产生。这些活性氧分子可以杀灭入侵的病原微生物，但同时由于活性氧分子反应的非特异性，它们也会对宿主的细胞、组织和器官造成严重伤害，进而导致对虾生理机能的损伤和免疫系统的破坏。所以，消除对虾体内因过度免疫反应产生的过量氧自由基将能够增强其抵御病原侵染的能力，提高免疫力。本论文从中国明对虾体内克隆了线粒体型超氧化物歧化酶（mMnSOD）、胞质型超氧化物歧化酶（cMnSOD）、过氧化氢酶（Catalase）和过氧化物还原酶（Peroxiredoxin）等四种与免疫系统相关的抗氧化酶基因，分析了它们的分子结构特征，组织分布及应答不同病原刺激的表达变化模式，并对其中的mMnSOD基因和Peroxiredoxin基因进行了体外重组表达、分离纯化和酶活性分析。 采用RACE技术从中国明对虾血细胞中克隆了两个超氧化物歧化酶（SOD）基因，通过序列比对分析发现，其中一个为mMnSOD基因，另一个为cMnSOD基因。mMnSOD基因的cDNA全长为1185个碱基，其中开放阅读框为660个碱基，编码220个氨基酸，其中推测的信号肽为20个氨基酸。多序列比对结果显示中国明对虾mMnSOD基因的推导氨基酸序列与罗氏沼虾、蓝蟹的推导氨基酸序列同源性分别为88%和82%。Northern blot结果表明，该基因在对虾的肝胰脏、血细胞、淋巴器官、肠、卵巢、肌肉和鳃等组织中均有表达。半定量RT-PCR结果显示，对虾感染病毒3 h时，该基因在血细胞和肝胰脏中的转录水平显著升高。此外，通过构建原核表达载体，本研究对该基因进行了体外重组表达，并对纯化的重组蛋白进行了质谱鉴定和酶活分析。cMnSOD基因的cDNA全长为1284个碱基，其中开放阅读框为861个碱基，编码287个氨基酸。多序列比对结果显示中国明对虾cMnSOD基因的推导氨基酸序列与斑节对虾和凡纳滨对虾的同源性高达98%和94%。组织半定量结果显示，cMnSOD基因在对虾被检测的各个组织中均有表达。 另外，半定量RT-PCR结果表明，对虾感染病毒23h时，该基因在肝胰脏中的转录上升到正常水平的3.5倍；而感染后59 h时，该基因在血细胞中的转录上升到正常水平的2.5倍。 利用根据其他生物过氧化氢酶保守氨基酸序列设计的简并引物，结合RACE技术，从中国明对虾肝胰脏中克隆到了过氧化氢酶基因的部分片段，片段长1725个碱基。多序列比对结果发现目前所得中国明对虾Catalase基因部分片段的推导氨基酸序列与罗氏沼虾和皱纹盘鲍Catalase氨基酸序列的同源性分别达到95%和73%。通过实时荧光定量PCR技术对中国明对虾Catalase基因在各个组织中的分布情况及病毒感染后该基因在血细胞和肝胰脏中的转录变化进行了研究。结果发现，该基因在肝胰脏、鳃、肠和血细胞中表达水平较高，在卵巢、淋巴器官和肌肉中的表达水平相对较弱；感染病毒23 h和37 h时，对虾血细胞和肝胰脏中该基因mRNA的表达量分别出现显著性上升。 依据中国明对虾头胸部cDNA文库提供的部分片段信息，结合SMART-RACE技术，从中国明对虾肝胰脏中克隆到了过氧化物还原酶基因（Peroxiredoxin）， 该基因的cDNA全长为942个碱基，其中开放阅读框为594个碱基，编码198个氨基酸。中国明对虾Peroxiredoxin基因的推断氨基酸序列与伊蚊、文昌鱼和果蝇等Peroxiredoxin基因的推断氨基酸序列同源性分别为77%、76%和73%。其蛋白理论分子量为22041.17 Da，pI为5.17。Northern blot结果表明，Peroxiredoxin基因在对虾的肝胰脏、血细胞、淋巴器官、肠、卵巢、肌肉和鳃等组织中均有表达。实时荧光定量PCR结果显示，弧菌感染后，该基因在对虾血细胞和肝胰脏中的转录水平都有明显变化并且表达模式不同。另外，对该基因进行了体外重组表达，并对纯化的重组蛋白进行了质谱鉴定和酶活性分析。酶活性分析表明，复性后的重组蛋白能在DTT存在的条件下还原H2O2。

非均质储层叠前地震反演技术研究及应用

(1) I research on the relationship between elastic parameters, lithology and liquid. It is a physical base for pre-stack seismic inversion. I research all kinds of approximate expressions of Zoeppritz function. Then the relation of all kinds of approximate expressions can be confirmed. The geological model of water sand and gas sand in different depth was designed. Moreover I research on precision of all kinds of approximate expressions. (2) In process of seismic data which aim at amplitude recovery and apply in pre-stack seismic inversion, I advance to adopt double flow chart for different aim. Pre-stack noise elimination, real amplitude recovery and NMO correction of long offset are the key taches. (3) I made a systemic expatiate for the thinking and applicability about all kinds of expressions of elastic impedance. And mathematical model was applied to compare the precision with all kinds of expressions of elastic impedance. I propose a new pre-stack simultaneous inversion which is based on the Zoppritz function and simulated annealing algorithm. This method can ensure calculation precision of reflection coefficient from different incident angle and get a global optimum solution. Therefore this method improves the precision of pre-stack seismic inversion. (4) The object function of P-S wave pre-stack simultaneous inversion was established. I compared the precision and convergence between simultaneous inversion and P-wave inversion. And the results show that simultaneous inversion is superior to P-wave inversion. Through the study of AVO event of transformed wave, AVO characters of different kinds of gas sand were analyzed. (5) I carried out the study work of pre-stack seismic inversion for carbonate reservoir in middle of Tarim basin and sand shale reservoir in Sulige Area of Erdos Basin. The method and technology in this paper was applied to practical work. And I made a prediction for heterogeneous reservoir. Moreover it acquires a good application effect. Key Word: reflection coefficient， amplitude recovery， pre-stack seismic inversion， Heterogeneous reservoir，prediction.

反射地震转换波成像方法研究

Multi-waves and multi-component get more and more attentions from oil industry. On the basis of existent research results, My research focuses on some key steps of OBC 4C datum processing. OBC datum must be preprocessed quite well for getting a good image. We show a flow chart of preprocess including attenuation of noise on multi-component datum、elimination ghost by summing P and Z and rotation of horizontal components. This is a good foundation for the coming steps about OBC processing. How to get exact converted point location and to analyze velocity are key points in processing reflection seismic converted wave data. This paper includes computing converted point location, analyzing velocity and nonhyperbolic moveout about converted waves. Anisotropic affects deeply the location of converted wave and the nonhyperbolic moveout. Supposed VTI, we research anisotropic effect on converted wave location and the moveout. Since Vp/Vs is important, we research the compute method of Vp/Vs from post-stack data and pre-stack data. It is a part of the paper that inversing anisotropic parameter by traveltime. Pre-stack time migration of converted wave is an focus, using common-offset Kirchhoff migration, we research the velocity model updating in anisotropic media. I have achieved the following results: 1) using continued Fractions, we proposed a new converted point approximate equation, when the offset is long enough ,the thomsen’s 2 order equation can’t approximate to the exact location of converted point, our equation is a good approximate for the exact location. 2) our new methods about scanning nonhyperbolic velocity and Vp/Vs can get a high quality energy spectrum. And the new moveout can fit the middle and long offset events. Processing the field data get a good result. 3) a new moveout equation, which have the same form as Alkhalifah’s long offset P wave moveout equation, have the same degree preciseness as thomsen’s moveout equation by testing model data. 4) using c as a function of the ratio offset to depth, we can uniform the Li’s and thomsen’s moveout equation in a same equation, the model test tell us choice the reasonable function C can improve the exact degree of Li’s and thomsen’s equation. 5) using traveltime inversion ,we can get anisotropic parameter, which can help to flat the large offset event and propose a model of anisotropic parameter which will useful for converted wave pre-stack time migration in anisotropic media. 6）using our pre-stack time migration method and flow, we can update the velocity model and anisotropic parameter model then get good image. Key words: OBC, Common converted Point (CCP), Nonhyperbolic moveout equation, Normal moveout correction, Velocity analysis, Anisotropic parameters inversion, Kirchhoff anisotropic pre-stack time migration, migration velocity model updating

表面相关多次波衰减方法与应用研究

The function of seismic data in prospecting and exploring oil and gas has exceeded ascertaining structural configuration early. In order to determine the advantageous target area more exactly, we need exactly image the subsurface media. So prestack migration imaging especially prestack depth migration has been used increasingly widely. Currently, seismic migration imaging methods are mainly based on primary energy and most of migration methods use one-way wave equation. Multiple will mask primary and sometimes will be regarded as primary and interferes with the imaging of primary, so multiple elimination is still a very important research subject. At present there are three different wavefield prediction and subtraction methods: wavefield extrapolation; feedback loop; and inverse-scattering series. I mainly do research on feedback loop method in this paper. Feedback loop method includs prediction and subtraction.Currently this method has some problems as follows. Firstly, feedback loop method requires the seismic data used to predict multiple is full wavefield data, but usually the original seismic data don’t meet this assumption, so seismic data must be regularized. Secondly, Multiple predicted through feedback loop method usually can’t match the real multiple in seismic data and they are different in amplitude, phase and arrrival time. So we need match the predicted multiple and that in seismic data through estimating filtering factors and subtract multiple from seismic data. It is the key for multiple elimination how to select a correct matching filtering method. There are many matching filtering methods and I put emphasis on Least-square adaptive matching filtering and L1-norm minimizing adaptive matching filtering methods. Least-square adaptive matching filtering method is computationally very fast, but it has two assumptions: the signal has minimum energy and is orthogonal to the noise. When seismic data don’t meet the two assumptions, this method can’t get good matching results and then can’t attenuate multiple correctly. L1-norm adaptive matching filtering methods can avoid these two assumptions and then get good matching results, but this method is computationally a little slow. The results of my research are as follows: 1. Proposed a method that interpolates seismic traces based on F-K migration and demigration. The main advantage of this method is that it can interpolate seismic traces in any offsets. It shows this method is valid through a simple model. 2. Comparing different Least-square adaptive matching filtering methods. The results show that equipose multi-channel adaptive matching filtering methods can get better results of multiple elimination than other matcing methods through three model data and two field data. 3. Proposed equipose multi-channel L1-norm adaptive matching filtering method. Because L1-norm is robust to large amplitude differences, there are no assumption on the signal has minimum energy and orthogonality, this method can get better results of multiple elimination. 4. Research on multiple elimination in inverse data space. The method is a new multiple elimination method and it is different from those methods mentioned above.The advantages of this method is that it is simple in theory and no need for the adaptive subtraction and computationally very fast. The disadvantage of this method is that it is not stabilized in its solution. The results show that equipose multi-channel and equipose pesudo-multi-channel least-square matching filtering and equipose multi-channel and equipose pesudo-multi-channel L1-norm matching filtering methods can get better results of multiple elimination than other matcing methods through three model data and many field data.