bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unconventional Reservoir Modeling of a Gas Field in the Nile Delta of Egypt
Authors: Daoud Ahmed , Hegazy Osama , Hazem Yasser , Lotfy Mohamed , Youssef Samir , Bustami Sami Salah , El Hawary Anas 
Published: March 2008

AbstractGas reservoirs in the Nile Delta of Egypt are characterized vertically by its thin beds of sands and shale and laterally by severe variations in facies. These challenges in the static modeling have a strong impact in the dynamic modeling which can be summarized in the following points. First, the vertical sequence of sands and shale leads to the difficulty in detecting a single gas-water contact in the field. Second, the vertical heterogeneity leads to the use of fine gridding especially in the vertical direction to accurately simulate the fluid flow in the reservoir. Third, the lateral variation in facies forces to use different saturation functions at different parts of the reservoir.The dynamic behavior of pressure and production performance from few wells (total seven wells) producing from this field show severe vertical discrepancy in pressure, gas and water production. This adds another challenge in the dynamic modeling and leads to dividing the field into three main reservoirs that are completely isolated with each has different reservoir and production characters.Due to these challenges, we developed an unconventional approach to model this field and estimate its gas in place that honors both static and dynamic data. First, we used the concept of initialization by enumeration instead of the conventional approach of initialization by equilibration that requires accurate detection of gas-water contact. The initial pressures are obtained from MDT (Modular Dynamic Tester) data and the water saturation are obtained from the petrophysical analysis in initial wells and populated in the reservoir to honor the seismic and the production data. Second, we used low vertical permeability to simulate the vertical variations in sand-shale sequence. This also helps in reducing the severity of the phases being not in equilibrium due to the initialization by enumeration. Third, we used fine gridding to capture the heterogeneous variation in property. To reduce the CPU time for running one single fine grid model, we divided it into three different models each represent one reservoir with running each model separately. Both production and pressure data confirms that these reservoirs are completely isolated and no wells are producing commingled from these reservoirs thus separating them will not have any effect on its performance.This work summarizes the workflow we developed in the dynamic modeling of this field, the history match approach we used to calibrate the model and finally the suggested optimum development plan to increase its reserves.
Enhancement of Gas Management for Flaring Reduction in KOC (West Kuwait)
Authors: Al-Kandari Ali , Ray Siddhartha 
Published: March 2008

Abstract
Reduction of gas flaring while sustaining the oil production target of 500 MBOPD from the West Kuwait field of KOC is a challenge. There are some reliability issues within the existing set up of West Kuwait oil & gas processing facilities in term of gas and condensate management which sometimes causes very high flaring. Moreover high flaring is also triggered whenever there is any problem occurs in downstream units in the Refinery.
Presently the average flaring from West Kuwait field is very high and reaches up to 30% of the total gas production. KOC has developed road map for gradual reduction of gas flaring to achieve 1% flaring and initiated several short term and long term initiatives to improve reliability & availability of the gas processing facilities and gas distribution network.
Sol–Gel Process
Authors: Landau Miron V. 
Published: March 2008

AbstractThe sections in this article areIntroductionPhysico‐Chemical Basis and Principles of Sol–Gel Processing for the Preparation of Porous SolidsActivation of Sol–Gel PrecursorsPolycondensationGelation/Aging/WashingGel Drying/DesolvationStabilization of Xerogels and AerogelsApplication of Sol–Gel Processing for the Preparation of Solid CatalystsBulk Catalytic‐Phase Materials: Xerogels and AerogelsA Monometallic Catalytic Materialsa Aluminab Chromiac TitaniaB Multimetallic Composite Catalytic Phasesa Spinel Compoundsb Hydrotalcitesc PerovskitesCatalytic Materials and Modifiers Entrapped in Porous MatricesA Atoms or Molecular Substances Entrapped by Co‐Condensation at the Colloidization Stepa Mixed Metal Oxides Xerogels and Aerogelsb Hybrid Organic–Inorganic Interphase CatalystsB Molecular Substances Adsorbed or Entrapped at the Gelation Stepa Functionalized Organic Catalystsb Inorganic Molecular Catalystsc EnzymesC Nanoparticles of Catalytic Phases Entrapped in Inorganic Porous Matricesa Metalsb Other Inorganicsc Functionalized and Templating PolymersCatalytic Coatings, Films, and MembranesMonolith CoatingMicroreactorsThin, Nanometric Catalytic FilmsCatalytic MembranesSummary
Preparation and adsorption properties of polyethylenimine containing fibrous adsorbent for carbon dioxide capture
Authors: Li Peiyuan , Zhang Sujuan , Chen Shuixia , Zhang Qikun , Pan Junjian , Ge Bingqing 
Published: March 2008

AbstractWe successfully prepared a novel fibrous adsorbent for carbon dioxide (CO2) capture by coating polyethylenimine (PEI) on a glass fiber matrix, using epoxy resin (EP) as crosslinking agent. The physicochemical properties of the fibrous adsorbents were characterized in terms of Fourier transform infrared spectrometry and thermogravimetric analysis. Factors that affected the adsorption capacity of the fibrous adsorbent were studied, including the crosslinking agent dosage, coating weight, moisture, adsorption temperature, and CO2 concentration of the simulated flue gas. The experimental results indicate that the properly crosslinked fibrous adsorbent had a high thermal stability at about 280°C. With a PEI/EP ratio of 10:1, a maximum adsorption capacity of 276.96 mg of CO2/g of PEI was obtained at 30°C. Moisture had a promoting influence on the adsorption of CO2 from flue gas. The CO2 adsorption capacity of the fibrous adsorbent in the presence of moisture could be 19 times higher than that in dry conditions. The fibrous adsorbent could be completely regenerated at 120°C. The CO2 adsorption capacity of the regenerated fibrous adsorbent was almost the same as that of the fresh adsorbent. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Lignin and ethylcellulose as polymers in controlled release formulations of urea
Authors: Fernández‐Pérez M. , Garrido‐Herrera F. J. , González‐Pradas E. , Villafranca‐Sánchez M. , Flores‐Céspedes F. 
Published: March 2008

AbstractLignin and ethylcellulose (EC) have been used for the preparation of controlled release (CR) formulations of urea. The lignin matrixes were prepared by mixing the urea with kraft lignin (UL) under melting conditions. They were also crushed and sieved to obtain granules of size between 0.5–1, 1–2, 2–3 and 3–5 mm. The coated urea granules were produced in a Wurster‐type fluidized‐bed equipment, using an ethanolic solution of EC on two different polymer levels. Having researched the encapsulation efficiency (EE) and the homogeneity of the CR formulations, kinetic‐release experiments were carried out in water. A high EE was reached, it oscillated between 95.12% for the system coated with 20% of EC and 97.18% for the 1 mm < d < 2 mm UL system. The rate of urea release from CR granules diminished in all cases in relation to nonformulated urea, being the latter completely dissolved in less than 0.5 h, but it took at least 48 h to release the 90% of urea from the EC coated formulations. Using an empirical equation, the time taken for 50% of the active ingredient to be released into water (T50) was calculated. From the analysis of the T50 values, we can deduce that the release rate of urea can be controlled mainly by selecting the granule size for lignin CR systems and changing the thickness of the coating film for EC coated granules. The variation order of T50 values, UL (0.5 mm < d < 1.0 mm) < UL (1.0 mm < d < 2.0 mm) < UL (2.0 mm < d < 3.0 mm) < UL (3.0 mm < d < 5.0 mm) < UEC10 < UEC20, showed that the presence of EC in formulations retarded the release of urea in relation to those prepared with lignin. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of rubber curing ingredients and phenolic‐resin on mechanical, thermal, and morphological characteristics of rubber/phenolic‐resin blends
Authors: Derakhshandeh Babak , Shojaei Akbar , Faghihi Morteza 
Published: March 2008

AbstractThis article examines the physical and mechanical characteristics of mixtures of two different synthetic rubbers, namely styrene‐butadiene rubber (SBR) and nitril‐butadiene rubber (NBR), with novolac type phenolic‐resin (PH). According to Taguchi experimental design method, it is shown that the addition of PH increases the crosslinking density of rubber phase probably due to its curative effects. Thermal analysis of the blends indicates that, contrary to NBR/PH blend, thermal stability of SBR/PH blend is dependent on sulfur content due to predominant polysulfidic crosslinks formed in SBR. Slight shift in glass‐transition temperature (Tg) of pure SBR and NBR vulcanizates by the addition of PH suggests that both SBR/PH and NBR/PH are incompatible blends with a partially soluble PH in the rubber phase. Two‐phase morphology of the mixtures is also evidenced by scanning electron microscopy. Correlation of the rubber/PH modulus versus PH concentration by Halpin‐Tsai model shows a deviation from the model. Presence of PH in the rubber phase is thought to vary the mechanical properties of the rubber phase by changing both the crosslinking density and rigidity of the molecular network of the rubber, leading to misuse of modulus of pure rubber in Halpin‐Tsai equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Seven‐week embryo with gastroschisis, multiple anomalies, and physiologic hernia suggests early onset of gastroschisis
Authors: Byrne Janice L. B. , Feldkamp Marcia L. 
Published: March 2008

AbstractGastroschisis is an increasingly common birth defect involving the development of the ventral body wall. Extrusion of the bowel is usually paraumbilical, usually right sided, and associated anomalies are less common than in omphalocele. Recently, hypotheses regarding the timing of the typical gastroschisis defect have come into question. Unlike previous theories, Feldkamp et al. (2007) has postulated that gastroschisis occurs much earlier in development, before abdominal wall closure, which is completed by about 35 days postconception. We present a case of a spontaneously aborted dysmorphic embryo which exhibits features of the normal physiologic herniation of the midgut as well as gastrochisis. The co‐existence of the abdominal wall defect in this abnormal embryo with the physiologic hernia supports the early development of this defect and also illustrates the causal heterogeneity of gastroschisis. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.
Temperature effects on the aerobic metabolism of glycogen‐accumulating organisms
Authors: Lopez‐Vazquez Carlos M. , Song Young‐Il , Hooijmans Christine M. , Brdjanovic Damir , Moussa Moustafa S. , Gijzen Huub J. , van Loosdrecht Mark C.M. 
Published: March 2008

AbstractShort‐term temperature effects on the aerobic metabolism of glycogen‐accumulating organisms (GAO) were investigated within a temperature range from 10 to 40°C. Candidatus Competibacter Phosphatis, known GAO, were the dominant microorganisms in the enriched culture comprising 93 ± 1% of total bacterial population as indicated by fluorescence in situ hybridization (FISH) analysis. Between 10 and 30°C, the aerobic stoichiometry of GAO was insensitive to temperature changes. Around 30°C, the optimal temperature for most of the aerobic kinetic rates was found. At temperatures higher than 30°C, a decrease on the aerobic stoichiometric yields combined with an increase on the aerobic maintenance requirements were observed. An optimal overall temperature for both anaerobic and aerobic metabolisms of GAO appears to be found around 30°C. Furthermore, within a temperature range (10–30°C) that covers the operating temperature range of most of domestic wastewater treatment systems, GAOs aerobic kinetic rates exhibited a medium degree of dependency on temperature (θ = 1.046–1.090) comparable to that of phosphorus accumulating organisms (PAO). We conclude that GAO do not have metabolic advantages over PAO concerning the effects of temperature on their aerobic metabolism, and competitive advantages are due to anaerobic processes. Biotechnol. Bioeng. 2008;101: 295–306. © 2008 Wiley Periodicals, Inc.
Syn, anti, and finally both conformations of cyclic AMP are involved in the CRP‐dependent transcription initiation mechanism in E. coli lac operon
Authors: Tutar Yusuf 
Published: March 2008

AbstractThe cyclic AMP receptor protein (CRP) of Escherichia coli regulates the activity of more than 150 genes. Allosteric changes in CRP structure accompanied by cAMP binding, initiate transcription through protein binding to specific DNA sequences. Initially, researchers proposed a two‐site cAMP‐binding model for CRP‐dependent transcription activation since biophysical methods showed two transitions during titration experiments. Three conformational states were considered; apo‐CRP, CRP:(cAMP)1 and CRP:(cAMP)2, and CRP:(cAMP)1 was proposed as the active form in this initial model. X‐ray data indicated an anti conformation and in contrast NMR experiments suggested a syn conformation for bound cAMPs. For years this paradigm about ligand conformation has been ambiguous. When CRP was crystallized with four bound cAMP in the last decade, two cAMPs were assigned to syn and the other two to anti conformations. Again three conformational states were suggested; apo‐CRP, CRP:(cAMP)2, and CRP:(cAMP)4. This new structure changed the view of CRP allosteric activation from a two‐site model to a four‐site model in the literature and the new model has been supported by biochemical and genetic data so far. According to the accepted model, binding of the first two cAMP molecules displays positive cooperativity, however, binding of the last two cAMP molecules shows negative cooperativity. This resolved the conflict between dynamic and static experimental observations. However, this new model cannot explain the initiation mechanism as previously proposed because functionally active CRP has only one cAMP equivalent. Gene regulation and transcription factors are involved in regulating both prokaryotic and eukaryotic metabolism. Although gene regulation and expression are much more complex in eukaryotes, CRP‐mediated transcription initiation is a model of general interest to life sciences and medicine. Therefore, the aim of this review is to summarize recent works and developments on the cAMP‐dependent CRP activation mechanism in E. coli. Copyright © 2008 John Wiley & Sons, Ltd.
Streptomyces Phospholipase D Mutants with Altered Substrate Specificity Capable of Phosphatidylinositol Synthesis
Authors: Masayama Atsushi , Takahashi Tetsuya , Tsukada Kaori , Nishikawa Seigo , Takahashi Rie , Adachi Masaatsu , Koga Kazushi , Suzuki Atsuo , Yamane Takashi , Nakano Hideo , Iwasaki Yugo 
Published: March 2008

AbstractThe substrate specificity of a phospholipase D (PLD) from Streptomyces antibioticus was altered by site‐directed saturation mutagenesis, so that it was able to synthesize phosphatidylinositol (PI). Mutations were introduced in the pld gene at the positions corresponding to three amino acid residues that might be involved in substrate recognition, and the mutated genes were expressed in Escherichia coli BL21 (DE3). High‐throughput screening of approximately 10 000 colonies for PI‐synthesizing activity identified 25 PI‐synthesizing mutant PLDs. One of these mutant enzymes was chosen for further analysis. The structure of the PI synthesized with the mutant enzyme was analyzed by HPLC‐MS and NMR. It was found that the mutant enzyme generated a mixture of structural isomers of PIs with the phosphatidyl groups connected at different positions of the inositol ring. The phosphatidylcholine‐hydrolyzing activity of the mutant PLD was much lower than that of the wild‐type enzyme. The mutant enzyme was able to transphosphatidylate various cyclohexanols with a preference for bulkier compounds. This is the first example of alteration of the substrate specificity of PLD and of PI synthesis by Streptomyces PLD.
A Sensitive and Selective Near‐Infrared Fluorescent Probe for Mercuric Ions and Its Biological Imaging Applications
Authors: Tang Bo , Cui Li Juan , Xu Ke Hua , Tong Li Li , Yang Gui Wen , An Li Guo 
Published: March 2008

AbstractA new mercury(II) near‐infrared region fluorescent probe 3,9‐dithia‐6‐monoazaundecane‐tricarbocyanine has been designed and synthesized. It consists of two functional moieties: the tricarbocyanine performs as the near‐infrared region fluorophore, and the 3,9‐dithia‐6‐monoazaundecane acts as the selected binding site for metal ions. The near‐IR excitation and emission profiles of the probe can minimize cell and tissue damage and avoid native fluorescence from natural cellular species. It exhibits fluorescence increase upon the binding of the Hg2+ based on the inhibition of the photoinduced electron transfer quenching mechanism. Excellent sensitivity and selectivity for mercuric ions are observed with this probe. The value of the system is demonstrated by its use in monitoring the real‐time uptake of Hg2+ within HepG2 cells and five day old zebrafish. The synthesis and remarkable properties of it help to extend the development of metal ions fluorescent probes for biological applications.
Understanding NMR J‐couplings by the theory of polarization propagators
Authors: Aucar Gustavo Adolfo 
Published: March 2008

AbstractPropagators are powerful theoretical tools that were first developed within the nonrelativistic (NR) regime and were applied to calculate atomic and molecular properties more than 30 years ago. The recent relativistic generalization of polarization propagators has shown that these propagators play a special role in describing the quantum origin of any molecular property and the broad implication of their particular definition. In this article, we give a general overview on fundamentals and applications of polarization propagators to one of the most important NMR spectroscopic parameters, the nuclear spin coupling mediated by the electronic system within both regimes: relativistic and NR. This presentation is given in a level that can be followed with a basic knowledge of quantum mechanics. Our aim is to show what one can learn about molecular electronic configurations, and also the transmission and influence of magnetic perturbations on electronic systems from basic theoretical elements like molecular orbitals, electronic excitation energies, coupling pathways, entanglement, etc. by using propagators. We shall use i) semiempirical models and ii) ab initio calculations at different levels of approach. We give a deep insight on the electronic origin of the Karplus' rule, the sign of indirect nuclear spin couplings, unusually large long‐range couplings, cooperativity effects, relativistic effects, and the origin of diamagnetism. Some of these analysis are based on previous publications, and some others are presented here for the first ime. © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part A 32A: 88–116, 2008.
Modulation of dendritic spine remodeling in the motor cortex following spinal cord injury: Effects of environmental enrichment and combinatorial treatment with transplants and neurotrophin‐3
Authors: Kim Byung G. , Dai Hai‐Ning , McAtee Marietta , Bregman Barbara S. 
Published: March 2008

AbstractIncomplete spinal cord injury (SCI) elicits structural plasticity of the spared motor system, including the motor cortex, which may underlie some of the spontaneous recovery of motor function seen after injury. Promoting structural plasticity may become an important component of future strategies to improve functional outcomes. We have recently observed dynamic changes in the density and morphology of dendritic spines in the motor cortex following SCI. The present study sought to test whether SCI‐induced changes in spine density and morphology could be modulated by potential strategies to enhance functional recovery. We examined the effects of enriched environment, transplants, and neurotrophin‐3 on the plasticity of synaptic structures in the motor cortex following SCI. Housing rats in an enriched environment increased spine density in the motor cortex regardless of injury. SCI led to a more slender and elongated spine morphology. Enriched housing mitigated the SCI‐induced morphological alterations, suggesting that the environmental modification facilitates maturation of synaptic structures. Transplantation of embryonic spinal cord tissue and delivery of neurotrophin‐3 at the injury site further increased spine density when combined with enriched housing. This combinatorial treatment completely abolished the injury‐induced changes, restoring a preinjury pattern of spine morphology. These results demonstrated that remodeling of dendritic spines in the motor cortex after SCI can be modulated by enriched housing, and the combinatorial treatment with embryonic transplants and neurotrophin‐3 can potentiate the effects of enriched housing. We suggest that synaptic remodeling processes in the motor cortex can be targeted for an intervention to enhance functional recovery after SCI. J. Comp. Neurol. 507:473–486, 2008. © 2008 Wiley‐Liss, Inc.
Methyloxy Substituted Heteroleptic Bis(phthalocyaninato) Yttrium Complexes: Density Functional Calculations
Authors: Zhang Yuexing , Cai Xue , Qi Dongdong , Yao Ping , Bian Yongzhong , Jiang Jianzhuang 
Published: March 2008

AbstractThe effects of alkyloxy substituents attached to one phthalocyanine ligand of three heteroleptic bis(phthalocyaninato) yttrium complexes Y(Pc)[Pc(α‐OCH3)4] (1), Y(Pc)[Pc(α‐OCH3)8] (2), and Y(Pc)[Pc(β‐OCH3)8] (3), as well as their reduction products {Y(Pc)[Pc(α‐OCH3)4]}− (4), {Y(Pc)[Pc(α‐OCH3)8]}− (5), and {Y(Pc)[Pc(β‐OCH3)8]}− (6) [H2Pc(α‐OCH3)4=1,8,15,22‐tetrakis(methyloxy)phthalocyanine; H2Pc(α‐OCH3)8=1,4,8,11,15,18,22,25‐octakis(methyloxy)phthalocyanine; H2Pc(β‐OCH3)8=2,3,9,10,16,17,23,24‐octakis(methyloxy)phthalocyanine] are studied by DFT calculations. Good consistency is found between the calculated results and experimental data for the electronic absorption, IR, and Raman spectra of 1 and 3. Introduction of electron‐donating methyloxy groups on one phthalocyanine ring of the heteroleptic double‐deckers induces structural deformation in both phthalocyanine ligands, electron transfer between the two phthalocyanine rings, changes in orbital energy and composition, shift of electronic absorption bands, and different vibrational modes of the unsubstituted and substituted phthalocyanine ligands in the IR and Raman spectra in comparison with the unsubstituted homoleptic counterpart Y(Pc)2. The calculations reveal that incorporation of methyloxy substituents at the nonperipheral positions has greater influence on the structure and spectroscopic properties of bis(phthalocyaninato) yttrium double‐deckers than at the peripheral positions, which increases with increasing number of substituents. Nevertheless, the substituent effect of alkyloxy substituents at one phthalocyanine ligand of the double‐decker on the unsubstituted phthalocyanine ring and on the whole molecule and the importance of the position and number of alkyloxy substituents are discussed. In addition, the effect of reducing 1–3 to 4–6 on the structure and spectroscopic properties of the bis(phthalocyaninato) yttrium compounds is also discussed. This systemic DFT study is not only useful for understanding the structure and spectroscopic properties of bis(phthalocyaninato) rare earth metal complexes but also helpful in designing and preparing double‐deckers with tunable structure and properties.