bluuebunny/crossref_metadata_2025_split huggingface dataset:
Persistence in real exchange rate convergence
Authors: Stengos Thanasis , Yazgan M. Ege 
Published: June 2013

AbstractIn this paper we use a long memory framework to examine the validity of the Purchasing Power Parity (PPP) hypothesis using both monthly and quarterly data for a panel of 47 countries over a 50 year period (1957–2009). The analysis focuses on the long memory parameter d that allows us to obtain different convergence classifications depending on its value. Our analysis allows for the presence of smooth structural breaks and it does not rely on the use of a benchmark. Overall the evidence strongly points to the presence of a long memory process, where 0.5<d<1. The implication of our results is that we find long memory mean reverting convergence, something that is also consistent with Pesaran, M. H., R. P. Smith, T. Yamagata, and L. Hvozdyk. 2009. “Pairwise Tests of Purchasing Power Parity.” Econometric Reviews 28: 495–521. In explaining the speed of convergence as captured by the estimated long memory parameter d we find impediments to trade such as distance between neighboring countries and sticky prices to be mainly responsible for the slow adjustment of real exchange rates to PPP rather than nominal rates for all country groups but Asia, where the opposite is true.
Redetermination of the structure of N-(2-benzoyl-4-chlorophenyl)-2- chloroacetamide, C15H11Cl2NO2
Authors: Yamuna Thammarse S. , Yathirajan Hemmige S. , Ramakrishna Ramesha A. , Gerber Thomas , Hosten Eric , Betz Richard 
Published: June 2013

Abstract C15H11Cl2NO2, triclinic, P1¯ (no. 2), a = 5.9681(3) Å, b = 9.9888(5) Å, c = 11.9936(6) Å, α = 81.800(2)°, β = 77.113(2)°, γ = 81.364(2)°, V = 684.6 Å3, Z = 2, Rgt(F) = 0.0314, wRref(F2) = 0.0818, T = 200 K.
Probing Small Protonated Water Clusters in Acetonitrile Solutions by 1H NMR
Authors: Sigalov Mark V. , Kalish Noah , Carmeli Benny , Pines Dina , Pines Ehud 
Published: June 2013

Abstract
In a previous publication by Kalish et al. (J. Phys. Chem. A 115 (2011) 4063) the existence of well defined small protonated water clusters in acetonitrile has been established by IR spectroscopy. Here we report on a 1H NMR study of triflic acid, CF3SO3H, in acetonitrile-water solutions. Using NMR we are able to corroborate the general solvation scheme we have proposed for the hydrated proton in acetonitrile as a function of the molar ratio between the strong mineral acid and water, n = [H2O]/[acid]. According to this scheme, backed now by both IR absorption spectroscopy and NMR measurements, the very strong triflic acid completely dissociates in acetonitrile/water solutions to yield the aqueous proton and the triflate anion when n > 1. Furthermore, increasing n results in the proton solvated in increasingly larger water clusters formed within the acetonitrile solution.
Clearly distinguishable by NMR are the smallest protonated water clusters, the protonated water monomer, H3
+O, and the protonated water dimer, H5
+O2, which dominate the solution for n = 1,2,3. For larger n the NMR study indicates the gradual increase of the average protonated water cluster size as a function of n while the proton inner solvation core more closely retaining the characteristics of a deformed protonated water dimer, (H2O-H+⋯OH2)
s
than that of the protonated water monomer (H3
+O)
s
.
The Genetic Architecture of Methotrexate Toxicity Is Similar in Drosophila melanogaster and Humans
Authors: Kislukhin Galina , King Elizabeth G , Walters Kelli N , Macdonald Stuart J , Long Anthony D 
Published: June 2013

Abstract
The severity of the toxic side effects of chemotherapy varies among patients, and much of this variation is likely genetically based. Here, we use the model system Drosophila melanogaster to genetically dissect the toxicity of methotrexate (MTX), a drug used primarily to treat childhood acute lymphoblastic leukemia and rheumatoid arthritis. We use the Drosophila Synthetic Population Resource, a panel of recombinant inbred lines derived from a multiparent advanced intercross, and quantify MTX toxicity as a reduction in female fecundity. We identify three quantitative trait loci (QTL) affecting MTX toxicity; two colocalize with the fly orthologs of human genes believed to mediate MTX toxicity and one is a novel MTX toxicity gene with a human ortholog. A fourth suggestive QTL spans a centromere. Local single-marker association scans of candidate gene exons fail to implicate amino acid variants as the causative single-nucleotide polymorphisms, and we therefore hypothesize the causative variation is regulatory. In addition, the effects at our mapped QTL do not conform to a simple biallelic pattern, suggesting multiple causative factors underlie the QTL mapping results. Consistent with this observation, no single single-nucleotide polymorphism located in or near a candidate gene can explain the QTL mapping signal. Overall, our results validate D. melanogaster as a model for uncovering the genetic basis of chemotoxicity and suggest the genetic basis of MTX toxicity is due to a handful of genes each harboring multiple segregating regulatory factors.
Oxidation Dynamics of a Chain of Aluminum Nanoparticles
Authors: Shekhar Adarsh , Wang Weiqiang , Clark Richard , Kalia Rajiv K. , Nakano Aiichiro , Vashishta Priya 
Published: June 2013

ABSTRACTMultimillion-atom molecular dynamics simulations are used to investigate burning behavior of a chain of three alumina-coated aluminum nanoparticles (ANPs), where particles one and three are heated above the melting temperature of pure aluminum. The mode and mechanism behind the heat and mass transfer from the hot ANPs (particles one and three) to the middle, cold ANP (particle two) are studied. The hot nanoparticles oxidize first, after which hot Al atoms penetrate into the cold nanoparticle. It is also found that due to the penetration of hot Al atoms, the cold nanoparticle oxidizes at a faster rate than in the initially heated nanoparticles. The calculated speed of penetration is found to be 54 m/s, which is within the range of experimentally measured flame propagation rates. As the atoms penetrate into the central ANP, they maintain their relative positions. The atoms from the shell of the central ANP form the first layer, which is followed by the atoms from the shell of the outer ANP making the second layer and lastly the atoms from the core of the outer ANPs form the third layer. In addition to heating the central ANP by convection, the ejected hot Al atoms from the outer ANPs initiate exothermic oxidation reactions inside the central ANP, leading to further heating within the central ANP. During 1 ns, all three ANPs fuse together, forming a single ellipsoidal aggregate.
The Influence of Modifiers on the Pigmentary Properties of Titanium Dioxide
Authors: Gleń Marta A. , Grzmil Barbara U. 
Published: June 2013

ABSTRACTIn the present work modified titanium dioxide products are prepared. The influence of introduced modifiers (phosphorus, potassium, aluminium, and tin) on the photoactivity, optical properties, and phase composition of titanium dioxide is studied. The molar contents of P2O5, K2O, Al2O3, and SnO2 in relation to TiO2 are 0.10, 0.18, 0.24, and 0.08-1.32 mol%, respectively. The research is aimed at obtaining the pigmentary rutile TiO2 with the highest possible photostability and improved optical properties.
Carrier Lifetime Measurements by Photoconductance at Low Temperature on Passivated Crystalline Silicon Wafers
Authors: Courtois Guillaume , Bruneau Bastien , Sobkowicz Igor P. , Salomon Antoine , Cabarrocas Pere Roca i 
Published: June 2013

ABSTRACTWe propose an implementation of the PCD technique to minority carrier effective lifetime assessment in crystalline silicon at 77K. We focus here on (n)-type, FZ, polished wafers passivated by a-Si:H deposited by PECVD at 200°C. The samples were immersed into liquid N2 contained in a beaker placed on a Sinton lifetime tester. Prior to be converted into lifetimes, data were corrected for the height shift induced by the beaker. One issue lied in obtaining the sum of carrier mobilities at 77K. From dark conductance measurements performed on the lifetime tester, we extracted an electron mobility of 1.1x104 cm².V-1.s-1 at 77K, the doping density being independently calculated in order to account for the freezing effect of dopants. This way, we could obtain lifetime curves with respect to the carrier density. Effective lifetimes obtained at 77K proved to be significantly lower than at RT and not to depend upon the doping of the a-Si:H layers. We were also able to experimentally verify the expected rise in the implied Voc, which, on symmetrically passivated wafers, went up from 0.72V at RT to 1.04V at 77K under 1 sun equivalent illumination.
CFD as a Tool For Pumping Strategy Evaluation on Matrix Acidizing Treatments
Authors: de Melo Andressa R. , de Oliveira Thiago Judson 
Published: June 2013

Abstract
Computational Fluid Dynamics (CFD) is a widely used technique to solve transport phenomena problems by the discretization of the conservation equations on the geometry of interest. Recently, several SPE papers use CFD to solve near wellbore problems. Features like perforated completions and fluid flow performance on multiple layers reservoirs are topics addressed. Other works focus on the reactive dissolution of carbonates. However, they are restricted to small scales due to the phenomenon complexity and high computational cost.
Most commercial CFD simulators allow users to implement their own models through user defined functions. This fact makes possible to simulate high complexity phenomena with lower computational cost. For instance, one could use an empirical model instead of solving the complete transport equations. CFD also allows a detailed view of flow aspects at wellbore scale, an important issue when flow paths or pressure drop are important to fluid placement.
This work addresses the implementation of an empirical wormhole propagation model on a CFD software. We have two goals: the simulation of different pumping strategies for matrix acidizing treatments aiming acid placement optimization and show how CFD could be a powerful tool to solve near wellbore problems.
Extending the Production Capacity in Sand Control Completions Using a Self-Mitigating Sand Screen
Authors: Yeh Charles S. , Mayer Christian S. , Howell David A. , Grueschow Eric R. , Angeles Renzo , Gillespie George A. , Sladic John , Simonds Randy 
Published: June 2013

Abstract
Stand-alone screens are often a simple and cost-effective sand control solution for long, multi-zone openhole completions. A recent technology advancement is a self-mitigating MazeFlo™ screen for enhanced sand screen reliability. Redundant screens and compartment mazes are incorporated to capture local sand ingress caused by screen damage without interrupting the overall well production. A common screen damage mechanism is screen erosion. The new screen extends the production capacity by increasing erosion resistance and providing self-mitigating functionality.
A self-mitigating screen includes an outer primary and an enclosed offset inner secondary screen. A maze compartment stands between the two screens to enable self-mitigation of screen damage. Without the primary screen damage, the secondary screen must withstand continuous fines production to maintain sand control capability in the well. If the primary screen is damaged, the erosive sand will enter the maze compartment and deposit on the secondary screen. The integrity of the maze compartment must be maintained until the compartment is fully packed and the well production is diverted to adjacent undamaged screens.
This paper discusses a methodology to evaluate the erosion resistance with regard to operating conditions in a self-mitigating screen. The methodology includes a suite of laboratory tests to establish an erosion baseline for a wire-wrapped screen. The erosion baseline, along with fluid flow modeling will provide design guidelines for a given operating condition. A proper MazeFlo screen design sustains the self-mitigation capability throughout the life of the well. The design envelope can be further expanded when combined with other technologies such as zonal isolation and inflow control devices.
Modification of the Kozeny-Carman Equation to Quantify Formation Damage by Fines in Clean Unconsolidated Porous Media
Authors: Krauss Eva D. , Mays David C. 
Published: June 2013

Abstract
Estimating formation permeability as a function of porosity, grain size, and the quantity and structure of fines is important for increasing hydrocarbon extraction from rock formations. The Kozeny-Carman equation can be used to estimate the permeability of clean unconsolidated media as a function of porosity and grain size, but does not account for the quantity and structure of deposited fines. This study shows how incorporating the volume of fines and a dimensionless bulk factor into the Kozeny-Carman equation can be used to model how the quantity and structure of deposited fines controls permeability. Several experimental studies from the literature are analyzed, representing a variety of fines (type and diameter), porous media, fluids, and flow velocities. These studies indicate that, when other variables are held constant, experiments conducted at higher flow velocity result in less plugging. For each experiment, a dimensionless bulk factor in the Kozeny-Carman equation was fitted, using the root mean square method, to best match the experimental data. Fitted values of the bulk factor were then correlated with the Peclet number to investigate how the structure of fines, quantified by the bulk factor, depends on the characteristics of the porous media, the depositing colloids, and the flow velocity. Larger bulk factors are observed at lower Peclet number, when diffusive transport dominates, which could result from more dendritic deposits. Smaller bulk factors are observed at higher Peclet numbers, when advective transport dominates, which could result from deposits that are more compact. By understanding how the bulk factor, and therefore the extent of permeability reduction, depends on the Peclet number, pumping schemes can be optimized in order to enable more complete hydrocarbon recovery. The primary application of this work is to optimize well flow rates to prevent or manage formation damage (i.e., plugging) resulting from deposition of fines in initially clean unconsolidated porous media.
A Neural Network Approach to Predict Formation Damage Due to Calcium Sulphate Precipitation
Authors: Foroutan Sadra , Moghadasi Jamshid 
Published: June 2013

Abstract
Sulphate and carbonate scale are the most important types of inorganic scales that can be observed in majority of reservoirs which encounter scaling problem during water injection.[8–9–10–11] Precipitation of these scales may ends to dramatic permeability reduction during water injection and due to their relative hardness and low solubility there are limited processes for their removal and prevention measures such as ‘squeeze’ inhibitor treatment has to be taken. In this regard, it is important to have a proper understanding of the kinetics of scale formation and trend of scale precipitation with considering the effective parameters on the phenomenon. This paper presents an experimental and theoretical study of calcium sulphate precipitation. A series of experiments were carried out to investigate the effect of different parameters on precipitation of calcium sulphate such as temperature, concentration of brine and flow rate. In addition, three different sets of experiments with the same procedure and different experimental condition were analyzed, compared and contrasted. The functional form of permeability reduction due to effect of different parameters in all experiments persuaded us to device a method to predict precipitation trend. Finally an artificial neural network was developed based on the data that obtained from experimental works. The network can predict permeability with considering effective parameters in each section of precipitation with very good accuracy and because of wide range of entrance data it can be considered as a reliable substitute for time/expense consuming experimental works in different range of time, flow rate, temperature and brine concentration.
Hydrolysis Effect on the Properties of a New Class of Viscoelastic Surfactant-Based Acid and Damage Caused by the Hydrolysis Products
Authors: He Zhenhua , Wang Guanqun , Nasr-El-Din Hisham A. , Holt Stuart 
Published: June 2013

Abstract
Viscoelastic surfactants (VES) have been widely used in acidizing and acid fracturing. They are used as diversion agents during matrix acid treatments and leakoff control agents during acid fracturing. At high temperatures, viscoelastic surfactants hydrolyze, resulting in phase separation after a certain time. Their viscosities significantly decrease and it is much easier for them to flow back and this causes much less damage to the formation.
In this study, 4 to 8 wt% of a new VES-acid system were tested at temperature up to 250°F over hydrolysis times of 0 to 6 hours. Then the solutions were neutralized by calcium carbonate until pH reached 4.5. An HP/HT rheometer was used to measure the viscosity of the spent acids. Mass spectrometry (MS) was conducted to analyze the hydrolysis products of the VES. Coreflood tests were also conducted on Indiana limestone to determine the effect of the hydrolysis products on the permeability of these cores. Temperature was set at 250°F and flow rate at 2.5 cm3/s.
The viscosities of all VES-acid systems remained high at the beginning of hydrolysis, which was good for acid diversion. After that, the VES acid systems experienced significant viscosity reduction because of phase separation; it became much easier for the spent acid to flow back. Coreflood experiments showed little damage caused to the Indiana limestone. MS results indicated that hydrolysis was achieved through the peptide bond. Fatty acids formed the top oil layer and amine-based molecules formed the aqueous phase.
This paper will summarize and discuss the details of viscosity changes of the acid systems of this kind of viscoelastic surfactant, the damage caused by the hydrolysis products, and how this kind of viscoelastic surfactant can be used to improve the treatments.
Non-Polymeric Permanent Clay Stabilizer for Shale Completions
Authors: Maley Darren , Farion Grant , O’Neil Bill 
Published: June 2013

Abstract
Many studies have been performed to identify chemical additives that will aid shale stability in large volume slick water fracturing treatments. Most of the targeted shale formations have a very low permeability, do not experience conventional leakoff and do not contain high amounts of swelling clays such as smectite, leading to a perception that the shale is not water sensitive. However, recent laboratory evaluations have shown that not all shales are stable in fresh water, destabilizing with fresh water contact and releasing fines which could potentially result in formation damage and reduce net fracture pack conductivity.
Previous studies of the ability of inorganic salts, temporary clay stabilizers, and permanent polymeric based clay stabilizers show that some of the common hydraulically fractured shales encounter stability problems when contacting fresh water. The studies have revealed that cationic polymeric permanent clay stabilizers improve the stability of the water sensitive shales. However, polymeric shale stabilizers are not without potential detriments. Polymers can lead to formation damage by blocking pore throats and reducing permeability. Additionally, the use of cationic polymers can limit the use of other chemical compounds used in treating fluids that may not be compatible with the cationic charge.
This paper will compare a non-polymeric permanent clay stabilizer to conventional cationic polymers, temporary clay stabilizers, and inorganic salts and demonstrate equivalent and, sometimes, improved performance. Laboratory data from shale stability (roller oven), capillary suction time (CST), and regained permeability (core flow) studies will be presented demonstrating the efficacy of this new compound. Shales selected for the study will include standard Pierre shale and a variety of commonly hydraulically fractured shales from North America. Additionally, chemical compatibility testing will demonstrate the benefits of the new compound over conventional cationic polymeric clay stabilizers.
Novel Water Shutoff Treatments in Gas Wells Using Petroleum External Solutions and Microemulsions
Authors: Lakatos I. J. , Lakatos-Szabo J. , Szentes G. , Vadaszi M. , Vago A. 
Published: June 2013

Abstract
The different water shutoff treatments based on in-situ gelation are attractive technologies; however, the field results often fall short of expectation. Reason of unsuccessful treatments might be that the flow resistance against water often develops not in the right time and reservoir space. Therefore, the primary aim of the research project was to develop such chemical systems, which will form the blocking phase triggered by mixing with water. As a novelty, water sensitive petroleum solutions and external microemulsions were developed, which are stable until they are diluted with water forming thus stable water external macroemulsions. Phase inversion of such metastable systems to stable ones in reservoir may radically restrict the water flow through their high viscosity and entrapment of the dispersed particles by the pores. The transformation and structure of phases were analyzed by photon correlation spectrometry, rheometry. The core studies confirmed that all metastable systems reduce the flow of water by 80–90% in water-saturated sandstone. Using chemical-free postflush the flow resistance remains substantial against water; meanwhile the permeability deterioration against gas is negligible.
The petroleum microemulsions are in phase of pilot test in two gas wells in the largest Hungarian oil/gas reservoir (Algyő field) with the aim at restricting the substantial water production. The concept and the developed technology is similar to the earlier silicon microemulsion field test, which yielded 3 106 m3 incremental gas production in the same reservoir and measurable decrease in water production. The metastable systems may offer an excellent opportunity for water shutoff in matured gas fields and gas storage facilities. The unique properties of the techniques are that flow resistance may occur only in water saturated reservoir space and in case of technical failure; the flow barrier can be eliminated by oil and gas injection.