bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sorption of polar and nonpolar aromatic compounds to two humic acids with varied structural heterogeneity
Authors: Sun Huiyu , Zhu Dongqiang , Mao Jingdong 
Published: July 2008

Abstract
The major objective of the present study was to evaluate the correlation between structural nature of humic acids (HAs) and sorption affinity of organic compounds with varied polarity. We compared the sorption behavior of three aromatic compounds—nonpolar phenanthrene (PHEN) and 1,2,4,5-tetrachlorobenzene (TeCB) and highly polar 2,4-dichlorophenol (DCP)—to a solid-phase coal humic acid (CHA) and a soil humic acid (SHA) suspended in aqueous solution. The structural nature of HAs was characterized using elemental analysis, ultraviolet absorbance, diffusive reflectance Fourier-transform infrared, and solid-state 13C nuclear magnetic resonance. The two tested HAs have very different structural properties: CHA consists primarily of poly(methylene)-rich aliphatics with high aromatic content and some COO/N–C=O but low polarity, while SHA consists of young materials of lignin, carbohydrates, and peptides with high polarity. In response to the structural heterogeneity of HAs, sorption of nonpolar and more hydrophobic solutes (PHEN, TeCB) to CHA is much greater than that to SHA because of the predominance of hydrophobic effects; however, disparities in sorption affinity between the two HAs become smaller for polar and less hydrophobic DCP because of the major role played by polar interactions. The influence of pH on the sorption of different solutes to the two HAs was also discussed. The results of the present work highlight the importance of structural heterogeneity of both solutes and HAs in the sorption process.
Scale-Corrected Ensemble Kalman Filtering Applied to Production-History Conditioning in Reservoir Evaluation
Authors: Lødøen O. P. , Omre H. 
Published: July 2008

SummaryIn reservoir evaluation problems, the reservoir properties are largely unknown. To infer these properties from observations of the reservoir production is referred to as history matching or production history conditioning. Traditionally, this is done by repeated fluid-flow simulations, where all the available production data are used simultaneously to arrive at a set of history-matched reservoir models. In recent years, the amount of data continuously collected from a reservoir under production has been on the increase. Hence, the need for automatic, continuous model updating is apparent. The ensemble Kalman filter has been shown to be suitable for this purpose. However, large reservoir evaluation problems require upscaling reservoir properties to perform the necessary number of fluid-flow simulations. Traditional ensemble Kalman filtering is shown to give bias in the production history conditioned reservoir representations. The loss in accuracy and precision introduced by performing fluid-flow simulations on a coarser scale should be accounted for, but this is rarely or never done. We introduce the scale-corrected ensemble Kalman filter approach in order to quantify the loss in accuracy and precision. A reference scale is defined and all uncertainty quantifications are made relative to this scale, although the fluid flow simulations are made on a coarser scale. The production history conditioned reservoir representation will be accurate with realistic precision measures on this reference scale. The methodology is demonstrated on a large case study inspired by the characteristics of the Troll field in the North Sea.
Modeling of Experiments on Water Vaporization for Gas Injection Using Traveling Waves
Authors: Zuluaga Elizabeth , Lake Larry W. 
Published: July 2008

Summary
Dry gas injected into wells will vaporize water from near the wellbore. The vaporization starts from the well and proceeds outward. Gas flowing to producers is in equilibrium with the reservoir brine, but water will be vaporized because the pressure drop that occurs toward the wellbore increases the ability of the gas to contain water. Thus, there are different mechanisms for injection and production.
For both gas injection and gas production, vaporization concentrates solids in the brine that will precipitate into the formation when sufficiently concentrated. This paper reports on a combined experimental and theoretical analysis on the vaporization portion of this problem for dry gas injection.
Experiments have been performed previously to determine the rate of water vaporization from Berea core samples at uniform initial water saturation (Zuluaga and Monsalve 2003). These experiments were performed by injecting dry methane into core samples that contained immobile water to represent water vaporization in a gas injector.
Effluent water concentration curves showed two vaporization periods: a constant rate period and a falling rate period. The existence of a constant rate period means that the mass transfer within the core is occurring at conditions of local equilibrium. We interpret the falling rate period as the result of a moving capillary transition zone in which the amount of water vaporized decreases slowly because of capillary pressure effects. The falling rate period is the consequence of capillary imbibition of a wetting phase at very small saturation.
We interpret the vaporization results with two traveling wave solutions. The first, which can be solved analytically, assumes that the capillary diffusion coefficient, D, and the volume fraction of water in the gaseous phase, Cwg, are constant. For this case, the results of the traveling wave solution are matched to the results of laboratory experiments by adjusting D. The second traveling-wave solution must be solved through numerical integration. In this case, the relative permeability scaling exponent is adjusted to match the laboratory experiments. The fitting provides insights into the nature of wetting phase flow at small saturation. Lastly, the experimental and mathematical procedure discussed in this paper is certainly a new method to obtain relative permeability exponents for the wetting phase at very low values of wetting-phase saturation (down to theoretically zero values).
Reduction of Wellbore Effects on Gas Inflow Evaluation Under Underbalanced Conditions
Authors: Aremu O. J. , Osisanya S. O. 
Published: July 2008

Summary
Wellbore storage effects have been identified to significantly smear the accuracy of evaluating reservoir productivity through the fluid outflow rate from the annulus during underbalanced drilling. Such effects have continuously introduced considerable errors in characterizing the reservoir during underbalanced drilling. Conceptually, because of the ready volume-changing ability of the gas, wellbore storage becomes a determining factor during underbalanced drilling of a gas reservoir. Wellbore storage could either cause decrease (unloading effects) or increase (loading effects) in the annular gas density, depending on the choke opening procedures. Correspondingly, annular fluid outflow rate is considerably affected. Because it is practically difficult to deduct the fluid-flow rate attributable to the wellbore storage from the total fluid outflow rate, reducing the influence of wellbore effects on the evaluation of gas-reservoir productivity is presented in this study. Volumetric production analysis at the wellbore-sand face is introduced through a mathematical modeling of inflow of gas bubbles into the wellbore. This mathematical modeling utilizes forces such as the viscous force, drilling fluid ejecting forces from the bit nozzles, buoyancy, interfacial tension, and gas-reservoir forces for its analyses. Some analytical results that are overshadowed by wellbore storage are presented and supported by extensive experimental studies.
Application of a New Grain-Based Reconstruction Algorithm to Microtomography Images for Quantitative Characterization and Flow Modeling
Authors: Thompson Karsten E. , Willson Clinton S. , White Christopher D. , Nyman Stephanie , Bhattacharya Janok P. , Reed Allen H. 
Published: July 2008

Summary
X-ray computed microtomography (XMT) is used for high-resolution, nondestructive imaging and has been applied successfully to geologic media. Despite the potential of XMT to aid in formation evaluation, currently it is used mostly as a research tool. One factor preventing more widespread application of XMT technology is limited accessibility to microtomography beamlines. Another factor is that computational tools for quantitative image analysis have not kept pace with the imaging technology itself.
In this paper, we present a new grain-based algorithm used for network generation. The algorithm differs from other approaches because it uses the granular structure of the material as a template for creating the pore network rather than operating on the voxel set directly. With this algorithm, several advantages emerge: the algorithm is significantly faster computationally, less dependent on image resolution, and the network structure is tied to the fundamental granular structure of the material. In this paper, we present extensive validation of the algorithm using computer-generated packings. These analyses provide guidance on issues such as accuracy and voxel resolution. The algorithm is applied to two sandstone samples taken from different facies of the Frontier Formation in Wyoming, USA, and imaged using synchrotron XMT. Morphologic and flow-modeling results are presented.
Improving Petrophysical Interpretation With Wide-Band Electromagnetic Measurements
Authors: Toumelin Emmanuel , Torres-Verdín Carlos , Bona Nicola 
Published: July 2008

Summary
Because of their sensitivity to ionic content and surface texture, wide-band electromagnetic (WBEM) measurements of saturated rocks exhibit frequency dispersions of electrical conductivity and dielectric constant that are influenced by a variety of petrophysical properties. Factors as diverse as fluid saturation, porosity, pore morphology, thin wetting films, and electrically charged clays affect the WBEM response of rocks. Traditional dielectric mixing laws fail to quantitatively and practically integrate these factors to quantify petrophysical information from WBEM measurements. This paper advances a numerical proof of concept for useful petrophysical WBEM measurements. A comprehensive pore-scale numerical framework is introduced that incorporates explicit geometrical distributions of grains, fluids and clays constructed from core pictures, and that reproduces the WBEM saturated-rock response on the entire kHz-GHz frequency range. WBEM measurements are verified to be primarily sensitive (a) in the kHz range to clay amounts and wettability; (b) in the MHz range to pore morphology (i.e., connectivity and eccentricity), fluid distribution, salinity, and clay presence; and (c) in the GHz range to porosity, pore morphology and fluid saturation. Our simulations emphasize the need to measure dielectric dispersion in the entire frequency spectrum to capture the complexity of the different polarization effects. In particular, it is crucial to accurately quantify the phenomena occurring in the MHz range where pore connectivity effects are confounded with clay polarization and pore/grain shape effects usually considered in dielectric phenomena. These different sensitivities suggest a strong complementarity between WBEM and NMR measurements for improved assessments of pore-size distribution, hydraulic permeability, wettability, and fluid saturation.
Multiscale Regularization of Flooding Optimization for Smart Field Management
Authors: Lien M. , Brouwer D. R. , Mannseth T. , Jansen J. D. 
Published: July 2008

Summary
Smart fields can provide enhanced oil recovery through the combined use of optimization and data assimilation. In this paper, we focus on the dynamic optimization of injection and production rates during waterflooding. In particular, we use optimal control theory in order to find an optimal well management strategy over the life of the reservoir that maximizes an objective function (e.g., recovery or net present value). Optimal control requires the determination of a potentially large number of (groups of) well rates for a potentially large number of time periods. However, the optimal number of well groups and time steps is not known a priori. Moreover, taking these numbers too large can slow down the optimization process and increase the chance of achieving a suboptimal solution. We investigate the use of multiscale regulariza-tion methods to achieve grouping of the control settings of the wells in both space and time. Starting out with a very coarse grouping, the resolution is subsequently refined during the optimization. The regularization is adaptive in that the multiscale parameterization is chosen based on the gradients of the objective function. Results for the numerical examples studied indicate that the regularization may lead to significantly simpler optimum strategies, while resulting in a better or similar cumulative oil production.
Low‐Dimensional Nanomaterials Based on Small Organic Molecules: Preparation and Optoelectronic Properties
Authors: Zhao Yong Sheng , Fu Hongbing , Peng Aidong , Ma Ying , Xiao Debao , Yao Jiannian 
Published: July 2008

AbstractThis article presents a comprehensive review of recent progress of research dedicated to low‐dimensional nanomaterials constructed from functional low‐molecular‐weight organic compounds, whose optoelectronic properties are fundamentally different from those of their inorganic counterparts. After introducing the development of inorganic and organic macromolecular nanomaterials, we begin with a general review of the construction strategies for achieving both zero‐dimensional (0D) and one‐dimensional (1D) nanostructures from small organic functional molecules. We then provide an overview of the unique optoelectronic properties induced by molecular aggregation in the nanostructures. Special emphasis is put on the luminescent properties that are different from those of the corresponding bulk materials, such as aggregation‐induced enhanced emission, fluorescence narrowing, multicolor emission, and tunable and switchable emissions from doped nanostructures. We conclude with a summary and our personal view of the direction of future development of organic opto‐functional nanomaterials and devices.
Conjugated Polymer Photovoltaic Materials with Broad Absorption Band and High Charge Carrier Mobility
Authors: Li Yongfang , Zou Yingping 
Published: July 2008

AbstractPolymer solar cells (PSCs) have attracted great attention in recent years because of their advantages of easy fabrication, low cost, light weight, and potential for flexible devices. However, the power conversion efficiency (PCE) of the PSCs needs to be improved for future commercial applications. Factors limiting the PCE of the PSCs include the low exploitation of sunlight due to the narrow absorption band of conjugated polymers, and the low charge‐transport efficiency in the devices due to the lower charge‐carrier mobility of the polymer photovoltaic materials. In this Research News article, recent progress in new conjugated polymer photovoltaic materials fabricated by our group and others is reviewed, including polythiophene (PT) and poly(thienylene vinylene) derivatives with conjugated side chains for a broad absorption band, crosslinked PT derivatives with conjugated bridges for higher hole mobility, and low‐bandgap donor–acceptor copolymers for broad, red‐shifted absorption to match the solar spectrum.
Micrometer‐ and Nanometer‐Sized Organic Single‐Crystalline Transistors
Authors: Tang Qingxin , Jiang Lang , Tong Yanhong , Li Hongxiang , Liu Yaling , Wang Zhaohui , Hu Wenping , Liu Yunqi , Zhu Daoben 
Published: July 2008

AbstractThe use of micrometer and nanometer‐sized organic single crystals to fabricate devices can retain all the advantages of single crystals, avoid the difficulties of growing large crystals, and provide a way to characterize organic semiconductors more efficiently. Moreover, the effective use of such “small” crystals will be beneficial to nanoelectronics. Here we review the recent progress of organic single‐crystalline transistors based on micro‐/nanometer‐sized structures, namely fabrication methods and related technical issues, device properties, and current challenges.
Rational Functionalization of Carbon Nanotubes Leading to Electrochemical Devices with Striking Applications
Authors: Yan Jie , Zhou Haojie , Yu Ping , Su Lei , Mao Lanqun 
Published: July 2008

AbstractAs one‐dimensional carbon nanostructures, carbon nanotubes (CNTs) are a member of the carbon family but they possess very different structural and electronic properties from other kinds of carbon materials frequently used in electrochemistry, such as glassy carbon, graphite, and diamond. Although the past decade has witnessed rapid and substantial progress in both the fundamental understanding of CNT‐oriented electrochemistry and the development of various kinds of electrochemical devices with carbon nanotubes, the increasing demand from both academia and industry requires CNT‐based electrochemical devices with vastly improved properties, such as good reliability and durability, and high performance. As we outline here, the smart functionalization of CNTs and effective methods for the preparation of devices would pave the way to CNT‐based electronic devices with striking applications.
Demonstration of loop reactor operation
Authors: Madai A. Y. , Sheintuch M. 
Published: July 2008

AbstractThis article is the first experimental demonstration of autothermal operation in an open loop reactor for catalytic abatement of low‐concentration volatile organic compounds (VOC). The system under investigation, which comprises three reactors organized in a loop with automatic switching of the feed position, has been successfully operated for ethylene oxidation. The influence of the feed flow rate and concentration on the pulse velocity and maximal temperature has been investigated. A simple analytical approximation for front velocity in the nonadiabatic one‐dimensional (1D) model has been derived and compared with the experimental results. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Optical Rotation of Achiral Compounds
Authors: Claborn Kacey , Isborn Christine , Kaminsky Werner , Kahr Bart 
Published: July 2008

AbstractOriented achiral molecules and crystals with D2d symmetry or one of its non‐enantiomorphous subgroups, S4, C2v, or Cs, can rotate the plane of transmitted polarized light incident in a general direction. This well‐established fact of crystal optics is contrary to the teaching of optical activity to students of organic chemistry. This Minireview gives an overview of the measurement and calculation of the chiroptical properties of some achiral compounds and crystals. Methane derivatives with four identical ligands related by reflection symmetry are quintessential optically inactive compounds according to the logic of van't Hoff. Analysis of the optical activity of simple achiral compounds such as H2O and NH3 provides general aspects of chiroptics that are not readily broached when considering chiral compounds exclusively. We show here, through the use of group theoretical arguments, the transformation properties of tensors, and diagrams, why some achiral, acentric compounds are optically active while others are not.
Origin and Endpoint of the Olfactory Nerve Fibers: As Described by Santiago Ramón y Cajal
Authors: Levine Catherine , Marcillo Alexander 
Published: July 2008

AbstractIllustration by author Catherine Levine inspired by the original drawing by Santiago Ramón y Cajal, featured in the article Origin and endpoint of the olfactory nerve fibers: As described by Santiago Ramón y Cajal. Depicted are large tufted cells and granule cells, a large stellate cell, a row of mitral cells and the arborization on the olfactory glomeruli, with olfactory nerve fibers streaming through the cartilage formation of the cribriform plate. See Levine et al., Anatomical Record 291:741–750.
Cloning and characterization of Bmrunt from the silkworm Bombyx mori during embryonic development
Authors: Liu Wenbin , Yang Fei , Jia Shihai , Miao Xuexia , Huang Yongping 
Published: July 2008

AbstractPair‐rule genes (genes that are expressed only in alternate segments, odd or even) play an important role in translating the broad gradients of upstream genes into dual segment periodicity for body plan patterning in Drosophila. However, homologues of pair‐rule genes show a remarkable diversity of expression patterns and functions in other insects. We cloned the homologue of runt in the silkworm Bombyx mori, an intermediate germband‐type insect. Whole‐mount in situ hybridization revealed three stripes arose one by one before gastrulation at the blastoderm stage. Five additional stripes were then generated sequentially as the growth zone elongated. Eight stripes appeared in a pair‐rule manner with two‐segment periodicity, each of which was confined to the posterior of an odd‐numbered parasegment. The weaker segmental secondary stripes emerged de novo in even‐numbered parasegments. The Bmrunt transcript vanished before blastokinesis and was then expressed again in the whole embryo. RNA interference for Bmrunt caused severely truncated, almost completely asegmental defects. This cadual‐like phenotype suggests that Bmrunt does not function as a pair‐rule gene in silkworm segmentation. Bmrunt is required for formation of most body segments and axis elongation in B. mori. Arch. Insect Biochem. Physiol. 2008. © 2008 Wiley‐Liss, Inc.
Monoterpenoid Indole Alkaloids Bearing an N4‐Iridoid from Gelsemium elegans
Authors: Yin Sheng , He Xiu‐Feng , Wu Yan , Yue Jian‐Min 
Published: July 2008

AbstractFive new alkaloids, gelseganines A–D (1–4) and humantenine N4‐oxide (5), were isolated from the stems and leaves of Gelsemium elegans. Compounds 1–4 represent a rare class of monoterpenoid indole alkaloids that bear an N4‐iridoid unit. The structures of 1–5 were determined by spectroscopic analysis, single‐crystal X‐ray diffraction, and chemical correlation, and their absolute configurations were elucidated by CD analysis. A plausible biogenetic pathway for alkaloids 1–5 was also postulated.
Stereoselective Synthesis of (−)‐Amphidinolide E
Authors: Kim Chan Hyuk , An Hyo Jung , Shin Won Kyo , Yu Wei , Woo Sang Kook , Jung Soon Kyu , Lee Eun 
Published: July 2008

AbstractThe total synthesis of (−)‐amphidinolide E was accomplished by following a synthetic scheme that incorporates the labile C2 stereocenter at a very late stage. The oxolane unit was prepared by β‐alkoxyacrylate radical cyclization. The enyne metathesis reaction was employed for the synthesis of the side chain. The Kocienski–Julia reaction was used for the union of the two major fragments, and the Kita macrolactonization protocol was used for macrolide synthesis.