黄土丘陵沟壑区退耕地土壤种子库特征与季节动态

采用野外样线取样与室内萌发相结合的方法研究了黄土高原丘陵沟壑区退耕地种子库的组成、密度、分布特征、季节动态、种子库类型。结果表明,土壤种子库中共发现50种植物的种子,隶属15个科,39个属,主要物种组成与密度季节间差异不显著;在演替过程中土壤种子库的物种数量与密度随退耕年限的增加表现出:增加-减少-增加的趋势,同时阳坡种子库密度波动较阴坡剧烈;土壤种子库密度年内变化范围为1 067~14 717粒/m2,土壤种子库平均密度是夏季>秋季>春季;研究区域退耕地土壤种子库类型属于以猪毛蒿为优势种,并具有其他一年生、多年生草本植物与灌丛种子的没有显著的季节动态的持久种子库,是物种适应黄土丘陵沟壑区特有生态环境条件的繁殖更新策略;从土壤种子库的物种组成、密度、类型来看,黄土丘陵沟壑区退耕地具有一定的自然恢复潜力。

Investigation of 3,3 ',5,5 '-tetramethylbenzidine as colorimetric substrate for a peroxidatic DNAzyme

in this Work, the suitability of 3,3',5,5'-tetramethylbenzidine sulfate (TMB) as the substrate of a DNAzyme catalytic system composed of a guanine-quadruplex DNA molecule and hemin was investigated. In the presence of H2O2, the hemin-DNA complex catalyzes the oxidation of TMB to produce two colored products, much like a peroxidase. The color-generating activity of this system could be influenced by several factors such as buffer type, pH value, DNA sequence, reaction time, and concentrations of both the hemin and H2O2. To illustrate the utility of this catalytic system, we designed a colorimetric assay, in which a synthetic oligonucleotide with a sequence complementary to the G-quadruplex DNA was used as the target. A detection limit of 1.86 nM was obtained. Our data have shown that TMB was an excellent colorimetric indicator that reported the peoxidase activities of the widely studied hemin-G-quadruplex DNAzyme system.

The formation of ordered nanoholes in binary, chemically similar, symmetric diblock copolymer blend films

Binary symmetric diblock copolymer blends, that is, low-molecular-weight poly(styrene-block-methyl methacrylate) (PS-b-PMMA) and high-molecular-weight poly(styrene-block-methacrylate) (PS-b-PMA), self-assemble on silicon substrates to form structures with highly ordered nanoholes in thin films. As a result of the chemically similar structure of the PMA and the PMMA block, the PMMA chain penetrates through the large PMA block that absorbs preferentially on the polar silicon substrate. This results in the formation of nanoholes in the PS continuous matrix.

Capillary liquid chromatographic-high-resolution mass spectrometric analysis of ribonucleotides

A method of capillary HPLC-high-resolution MS was developed for the trace analysis of ATP, GTP, dATP and dGTP Dimethylhexylamine (DMHA) was used as ion-pairing agent for the HPLC retention and separation of the nucleotides and positive ion electrospray time-of-flight MS was used for the detection. The application of capillary HPLC allowed minimal usage of DMHA while providing excellent peak retention and resolution, which significantly reduced the ion suppression in electrospray ionization-MS analysis and thus increased the sensitivity. Adduct ions of nucleotides and DMHA were used as quantitative ions in order to achieve the best sensitivity. DMHA concentration at 5 mM in the aqueous mobile phase at pH 7 was found to be the optimal conditions for the C Is capillary column. The method was applied to determine ATP level in cultured C6 glioma cells that were treated with toxic concentrations of Zn. The results showed that the cellular ATP level decreased from 2.7 pmol/cell (<10% cell death) in average control cell samples to 0.36 pmol/cell as the concentration of Zn increased to 120 mg/l (>35% cell death) in culture medium.

孤岛油田油藏动态模型和开发环境及剩余油分布

This paper is an important part of the national "863" topic :"Reservoir dynamic model, the development environment and the forecast of remaining oil". In this paper, multi-theory, method and technology are synthesized, and sufficiently use the computer method. We use unifies of qualitative and quota, unifies of macroscopic and microscopic, unifies of dynamic and quiescent description of reservoir, unifies of comprehensive research about reservoir and physical mathematical simulation, unifies of three-dimensional and four-dimensional description of reservoir to research the reservoir of channel sand in Gudao oilfield. and we do some research about the last 10 years of the more than 30 year high pressure water injection and polymer water flooding development, dynamic changes and geologic hazard of reservoir fluid field. It discloses the distribution, genesis and controlling factors. The main innovation achievement and the understanding are: we built-up the framework of the strata and structure, and found genetic type, spatial distribution and aeolotropism of the upper Guantao member. We form the macroscopic and microscopic reservoir model of dynamic evolution, disclose the character, distribution of the macroscopic and microscopic parameter，and the relationship with remaining oil. Next we built-up the model about hydrosialite, and find the styles, group of styles, formation mechanism and controlling factors of the reservoir, disclose the affection of the hydrosialite to remaining oil, pollution of the production environment of oilfield and geologic hazard. The geologic hazards are classified to 8 styles first time, and we disclose the character, distribution law, formation mechanism and controlling factors of the geologic hazard. We built-up the model of the distribution of remaining oil in different periods of Gudao oilfield, and disclose the macroscopic and microscopic formation mechanism of remaining oil in different periods, forecast the distribution of the mobile remaining oil, and find that the main cause of the dynamic evolution of all the sub-models of reservoir fluid field is the geologic process of the reservoir development hydrodynamic force. We develop the reservoir fluid field, research of environment disaster and the description about the support theory, method and technology. The use of this theory in Gudao oilfield has obtained very good economic efficiency, and deepened and develops development geology about the continental facies fault-trough basin, and theory of geologic hazard.

松辽盆地河流-三角洲体系高分辩率层序地层学、储层构形及非均质模型研究

This dissertation tries to combine the new theories of high-resolution sequence stratigraphy and reservoir architecture with fine sedimentology to form a integral theory system -"high-resolution sequence sedimentology", which can be applied widely ranging from the early petroleum exploration to the tertiary recovery stage in marine and terrestrial basin. So the west slope area in south of Songliao basin, in which, early-fine exploration have been developed, and Xingnan area of Daqing placantictine in high water-bearing and tertiary recovery stage, are selected as target areas to research and analyze. By applying high-resolution sequence stratigraphy theory as well as analysis of source area-facies, the west slope area has been divided into two source areas and three drainage systems and the following conclusions have been drawn: three high values sandstone areas, two sandstone pinchout zones and one stratigraphic pinchout overlap; the facies between Baicheng-Tongyu drainage system is frist ascertained as large-scale argillaceous filled plain facies; fine-grained braided channel-delta depositional system has been found; plane sedimentary facies and microfacies maps of different-scale sequence have been completed, and then twenty-eight lithologic traps have been detected in the east of Taobao-Zhenlai reverse fault zone; In no exploration area of the west, large-scale stratigraiphic overlap heavy oil reservoirs has first been found, which has become an important prograss. In Xingnan area, in the view of high-resolution sequence stratigraphy, the surface of unconformity (the bottom of SSC13) in P I group has been identified, and the following method and technique have been advanced: the division and correlation methods of short-scale base-level cycle sequence (SSC); the comprehensive research methods of SSC plane microfacies; the division technique of hierarchy and type of flow unit, the origin of large-scale composite sandbody and flow unit; And ,on the basis of these, 103 monosandstone bodies and 87 flow units of the third levels have been identified, and four levels of flow units model of five sandstone-bodies types have been established. Because it is a very difficult task all over the world to research architecture in subsurface monosandstone body, brings forward a series of techniques as follows: technique of researching architecture of thin interbed in subsurface monosandstone body; classification, type and liquid-resisting mechanism of thin interbed; multiple-remember vertical subsequence model of remaining oil in monosadstone body. Models of heterogeneity and architecture of thin interbed in five types of monosandstone body have been established. Applying these techniques, type and distribution of remaining oil in different types of monosandstone bodies have been predicated.

Dust-acoustic wave modulation in the presence of superthermal ions

A study is presented of the nonlinear self-modulation of low-frequency electrostatic (dust acoustic) waves propagating in a dusty plasma, in the presence of a superthermal ion (and Maxwellian electron) background. A kappa-type superthermal distribution is assumed for the ion component, accounting for an arbitrary deviation from Maxwellian equilibrium, parametrized via a real parameter kappa. The ordinary Maxwellian-background case is recovered for kappa ->infinity. By employing a multiple scales technique, a nonlinear Schrodinger-type equation (NLSE) is derived for the electric potential wave amplitude. Both dispersion and nonlinearity coefficients of the NLSE are explicit functions of the carrier wavenumber and of relevant physical parameters (background species density and temperature, as well as nonthermality, via kappa). The influence of plasma background superthermality on the growth rate of the modulational instability is discussed. The superthermal feature appears to control the occurrence of modulational instability, since the instability window is strongly modified. Localized wavepackets in the form of either bright-or dark-type envelope solitons, modeling envelope pulses or electric potential holes (voids), respectively, may occur. A parametric investigation indicates that the structural characteristics of these envelope excitations (width, amplitude) are affected by superthermality, as well as by relevant plasma parameters (dust concentration, ion temperature).

NON-GAUSSIAN STATISTICS OF OIL PRICING TIME-SERIES: A CASE STUDY

The stochastic nature of oil price fluctuations is investigated over a twelve-year period, borrowing feedback from an existing database (USA Energy Information Administration database, available online). We evaluate the scaling exponents of the fluctuations by employing different statistical analysis methods, namely rescaled range analysis (R/S), scale windowed variance analysis (SWV) and the generalized Hurst exponent (GH) method. Relying on the scaling exponents obtained, we apply a rescaling procedure to investigate the complex characteristics of the probability density functions (PDFs) dominating oil price fluctuations. It is found that PDFs exhibit scale invariance, and in fact collapse onto a single curve when increments are measured over microscales (typically less than 30 days). The time evolution of the distributions is well fitted by a Levy-type stable distribution. The relevance of a Levy distribution is made plausible by a simple model of nonlinear transfer. Our results also exhibit a degree of multifractality as the PDFs change and converge toward to a Gaussian distribution at the macroscales.

Rheological, mechanical and membrane penetration properties of novel dual drug systems for percutaneous delivery

In this study it has been demonstrated that mixtures of two solid drugs, ibuprofen and methyl nicotinate, with different but complementary pharmacological activities and which exist as a single liquid phase over a wide composition range at skin temperature, can be formulated as o/w emulsions without the use of an additional hydrophobic carrier. These novel dual drug systems provided significantly enhanced in vitro penetration rates through a model lipophilic barrier membrane compared to conventional individual formulations of each active. Thus, for ibuprofen, drug penetration flux enhancements of three- and 10-fold were observed when compared to an aqueous ibuprofen suspension and a commercial alcohol-based ibuprofen formulation, respectively. Methyl nicotinate penetration rates were shown to be similar for aqueous gels and emulsified systems. Mechanisms explaining these observations are proposed. Novel dual drug formulations of ibuprofen and methyl nicotinate, formulated within the liquid range at skin temperature, were investigated by oscillatory rheology and texture profile analysis. demonstrating the effects of drug and viscosity enhancer concentrations, and disperse phase type upon the rheological, mechanical and drug penetration properties of these systems. (C) 2000 Elsevier Science B.V. All rights reserved.

Electron-scale dissipative electrostatic solitons in multi-species plasmas

The linear and nonlinear properties of small-amplitude electron-acoustic solitary waves are investigated via the fluid dynamical approach. A three-component plasma is considered, composed of hot electrons, cold electrons, and ions (considered stationary at the scale of interest). A dissipative (wave damping) effect is assumed due to electron-neutral collisions. The background (hot) electrons are characterized by an energetic (excessively superthermal) population and are thus modeled via a κ-type nonthermal distribution. The linear characteristics of electron-acoustic excitations are discussed, for different values of the plasma parameters (superthermality index κ and cold versus hot electron population concentration β). Large wavelengths (beyond a threshold value) are shown to be overdamped. The reductive perturbation technique is used to derive a dissipative Korteweg de-Vries (KdV) equation for small-amplitude electrostatic potential disturbances. These are expressed by exact solutions in the form of dissipative solitary waves, whose dynamics is investigated analytically and numerically. Our results should be useful in elucidating the behavior of space and experimental plasmas characterized by a coexistence of electron populations at different temperatures, where electron-neutral collisions are of relevance.

Diamond microelectrodes for corrosion studies

Este trabalho teve como objetivos a produção, caracterização e aplicação de microelétrodos (MEs) de diamante como sensores amperométricos e potenciométricos em sistemas de corrosão nos quais a agressividade do meio e a presença de produtos de corrosão, constituem obstáculos que podem diminuir o desempenho, ou inviabilizar a utilização, de outros tipos de sensores. Os microeléctrodos são baseados em filmes finos de diamante dopado com boro (BDD – Boron Doped Diamond) depositados sobre fios de tungsténio afiados, através do método de deposição química a partir da fase vapor, assistida por filamento quente (HFCVD – Hot Filament Chemical Vapor Deposition). A otimização das diversas etapas de fabricação dos MEs deu origem ao desenvolvimento de um novo sistema de afiamento eletroquímico para obtenção destes fios e a várias opções para a obtenção dos filmes de diamante condutor e seu isolamento com resinas para exposição apenas da ponta cilíndrica. A qualidade cristalina dos filmes de diamante foi avaliada por espectroscopia de Raman. Esta informação foi complementada com uma caracterização microestrutural dos filmes de diamante por microscopia eletrónica de varrimento (SEM), em que se fez a identificação da tipologia dos cristais como pertencendo às gamas de diamante nanocristalino ou microcristalino. Os filmes de BDD foram utilizados na sua forma não modificada, com terminações em hidrogénio e também com modificação da superfície através de tratamentos de plasma RF de CF4 e O2 indutores de terminações C-F no primeiro caso e de grupos C=O, C-O-C e C-OH no segundo, tal como determinado por XPS. A caracterização eletroquímica dos MEs não modificados revelou uma resposta voltamétrica com elevada razão sinal/ruído e baixa corrente capacitiva, numa gama de polarização quasi-ideal com extensão de 3 V a 4 V, dependente dos parâmetros de crescimento e pós-tratamentos de superfície. Estudou-se a reversibilidade de algumas reações heterogéneas com os pares redox Fe(CN)6 3-/4- e FcOH0/+ e verificou-se que a constante cinética, k0, é mais elevada em elétrodos com terminações em hidrogénio, nos quais não se procedeu a qualquer modificação da superfície. Estes MEs não modificados foram também testados na deteção de Zn2+ onde se observou, por voltametria cíclica, que a detecção da redução deste ião é linear numa escala log-log na gama de 10-5-10-2 M em 5 mM NaCl. Realizaram-se também estudos em sistemas de corrosão modelares, em que os microeléctrodos foram usados como sensores amperométricos para mapear a distribuição de oxigénio e Zn2+ sobre um par galvânico Zn-Fe, com recurso a um sistema SVET (Scanning Vibrating Electrode Technique). Foi possível detetar, com resolução lateral de 100 μm, um decréscimo da concentração de O2 junto a ambos os metais e produção de catiões de zinco no ânodo. Contudo verificou-se uma significativa deposição de zinco metálico na superfície dos ME utilizados. Os MEs com superfície modificada por plasma de CF4 foram testados como sensores de oxigénio dissolvido. A calibração dos microeléctrodos foi efetuada simultaneamente por voltametria cíclica e medição óptica através de um sensor de oxigénio comercial. Determinou-se uma sensibilidade de ~0.1422 nA/μM, com um limite de deteção de 0.63 μM. Os MEs modificados com CF4 foram também testados como sensores amperométricos com os quais se observou sensibilidade ao oxigénio dissolvido em solução, tendo sido igualmente utilizados durante a corrosão galvânica de pares Zn-Fe. Em alguns casos foi conseguida sensibilidade ao ião Zn2+ sem que o efeito da contaminação superficial com zinco metálico se fizesse sentir. Os microeléctrodos tratados em plasma de CF4 permitem uma boa deteção da distribuição de oxigénio, exibindo uma resposta mais rápida que os não tratados além de maior estabilidade de medição e durabilidade. Nos MEs em que a superfície foi modificada com plasma de O2 foi possível detetar, por cronopotenciometria a corrente nula, uma sensibilidade ao pH de ~51 mV/pH numa gama de pH 2 a pH 12. Este comportamento foi associado à contribuição determinante de grupos C-O e C=O, observados por XPS com uma razão O/C de 0,16. Estes MEs foram igualmente testados durante a corrosão galvânica do par Zn-Fe onde foi possível mapear a distribuição de pH associada ao desenvolvimento de regiões alcalinas causadas pela redução do oxigénio, acima da região catódica, e de regiões ácidas decorrentes da dissolução anódica do ânodo de zinco. Com o par galvânico imerso em 50 mM NaCl registou-se uma variação de pH aproximadamente entre 4,8 acima do ânodo de zinco a 9,3 sobre o cátodo de ferro. A utilização pioneira destes MEs como sensores de pH é uma alternativa promissora aos elétrodos baseados em membranas seletivas.

A29 NMR spin-lattice relaxation study of paramagnetics -doped orthosilictes

A ~si MAS NMR study of spin-lattice relaxation behaviour in paramagnetic-doped crystalline silicates was undertaken, using synthetic magnesium orthosilicate (forsterite) and synthetic zinc orthosilicate (willemite) doped with 0.1% to 20% of Co(II), Ni(II), or CU(II), as experimental systems. All of the samples studied exhibited a longitudinal magnetization return to the Boltzmann distribution of nuclear spin states which followed a stretched-exponential function of time: Y=exp [- (tjTn) n], Ophase, and ion distribution complexities inherent in many of these systems.

Some Applications of Markov Additive Processes as Models in Insurance and Financial Mathematics

Cette thèse est principalement constituée de trois articles traitant des processus markoviens additifs, des processus de Lévy et d'applications en finance et en assurance. Le premier chapitre est une introduction aux processus markoviens additifs (PMA), et une présentation du problème de ruine et de notions fondamentales des mathématiques financières. Le deuxième chapitre est essentiellement l'article "Lévy Systems and the Time Value of Ruin for Markov Additive Processes" écrit en collaboration avec Manuel Morales et publié dans la revue European Actuarial Journal. Cet article étudie le problème de ruine pour un processus de risque markovien additif. Une identification de systèmes de Lévy est obtenue et utilisée pour donner une expression de l'espérance de la fonction de pénalité actualisée lorsque le PMA est un processus de Lévy avec changement de régimes. Celle-ci est une généralisation des résultats existant dans la littérature pour les processus de risque de Lévy et les processus de risque markoviens additifs avec sauts "phase-type". Le troisième chapitre contient l'article "On a Generalization of the Expected Discounted Penalty Function to Include Deficits at and Beyond Ruin" qui est soumis pour publication. Cet article présente une extension de l'espérance de la fonction de pénalité actualisée pour un processus subordinateur de risque perturbé par un mouvement brownien. Cette extension contient une série de fonctions escomptée éspérée des minima successives dus aux sauts du processus de risque après la ruine. Celle-ci a des applications importantes en gestion de risque et est utilisée pour déterminer la valeur espérée du capital d'injection actualisé. Finallement, le quatrième chapitre contient l'article "The Minimal entropy martingale measure (MEMM) for a Markov-modulated exponential Lévy model" écrit en collaboration avec Romuald Hervé Momeya et publié dans la revue Asia-Pacific Financial Market. Cet article présente de nouveaux résultats en lien avec le problème de l'incomplétude dans un marché financier où le processus de prix de l'actif risqué est décrit par un modèle exponentiel markovien additif. Ces résultats consistent à charactériser la mesure martingale satisfaisant le critère de l'entropie. Cette mesure est utilisée pour calculer le prix d'une option, ainsi que des portefeuilles de couverture dans un modèle exponentiel de Lévy avec changement de régimes.

Étude numérique des origines hémodynamiques des oscillations dans des réseaux de capillaires

En simulant l’écoulement du sang dans un réseau de capillaires (en l’absence de contrôle biologique), il est possible d’observer la présence d’oscillations de certains paramètres comme le débit volumique, la pression et l’hématocrite (volume des globules rouges par rapport au volume du sang total). Ce comportement semble être en concordance avec certaines expériences in vivo. Malgré cet accord, il faut se demander si les fluctuations observées lors des simulations de l’écoulement sont physiques, numériques ou un artefact de modèles irréalistes puisqu’il existe toujours des différences entre des modélisations et des expériences in vivo. Pour répondre à cette question de façon satisfaisante, nous étudierons et analyserons l’écoulement du sang ainsi que la nature des oscillations observées dans quelques réseaux de capillaires utilisant un modèle convectif et un modèle moyenné pour décrire les équations de conservation de masse des globules rouges. Ces modèles tiennent compte de deux effets rhéologiques importants : l’effet Fåhraeus-Lindqvist décrivant la viscosité apparente dans un vaisseau et l’effet de séparation de phase schématisant la distribution des globules rouges aux points de bifurcation. Pour décrire ce dernier effet, deux lois de séparation de phase (les lois de Pries et al. et de Fenton et al.) seront étudiées et comparées. Dans ce mémoire, nous présenterons une description du problème physiologique (rhéologie du sang). Nous montrerons les modèles mathématiques employés (moyenné et convectif) ainsi que les lois de séparation de phase (Pries et al. et Fenton et al.) accompagnés d’une analyse des schémas numériques implémentés. Pour le modèle moyenné, nous employons le schéma numérique explicite traditionnel d’Euler ainsi qu’un nouveau schéma implicite qui permet de résoudre ce problème d’une manière efficace. Ceci est fait en utilisant une méthode de Newton- Krylov avec gradient conjugué préconditionné et la méthode de GMRES pour les itérations intérieures ainsi qu’une méthode quasi-Newton (la méthode de Broyden). Cette méthode inclura le schéma implicite d’Euler et la méthode des trapèzes. Pour le schéma convectif, la méthode explicite de Kiani et al. sera implémentée ainsi qu’une nouvelle approche implicite. La stabilité des deux modèles sera également explorée. À l’aide de trois différentes topologies, nous comparerons les résultats de ces deux modèles mathématiques ainsi que les lois de séparation de phase afin de déterminer dans quelle mesure les oscillations observées peuvent être attribuables au choix des modèles mathématiques ou au choix des méthodes numériques.

Development and Analysis of a Compact Dual-Band Coplanar Antenna

The coplanar wave guide is an attractive device in microwave integrated circuits due to its uniplanar nature, ease of fabrication and low production cost. Several attempts are already done to explore the radiating modes in coplanar wave guide transmission lines. Usually coplanar wave guides are excited by an SMA connector with its centre conductor connected to the exact middle of the centre strip and the outer ground conductor to the two ground strips. The mode excited on it is purely a bound mode. The E-field distribution in the two slots are out of phase and there for cancels at the far field. This thesis addresses an attempt to excite an in phase E-field distribution in the two slots of the co planar wave guide by employing a feed asymmetry, in order to get radiation from the two large slot discontinuities of the coplanar waveguide. The omni directional distribution of the radiating energy can be achieved by widening the centre strip.The first part of the thesis deals with the investigations on the resonance phenomena of conventional coplanar waveguides at higher frequency bands. Then an offset fed open circuited coplanar waveguide supporting resonance/radiation phenomena is analyzed. Finally, a novel compact co planar antenna geometry with dual band characteristics, suitable for mobile terminal applications is designed and characterized using the inferences from the above study.