bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exchange Character of Caesium Ions onto Zirconium Tungstate
Authors: Sheha R.R. , El-Khouly S.H. 
Published: July 2011

Amorphous zirconium tungstate, an inorganic ion-exchanger, was synthesized under optimum conditions and used as a cation-exchange material for the removal of caesium ions from radioactive waste solutions under simulated conditions using batch techniques. The physical and chemical properties of the synthesized ion-exchanger were characterized using Fouriertransform (FT) infrared, X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques. Its chemical stability in various mineral acids, bases and organic solvents was also assessed. The data obtained reveal that the prepared exchanger had a good ionexchange capacity (1.34 mequiv/g towards Cs+ ions) and a high thermal and chemical stability. A hypothetical structural formula, Zr[WO2(OH)2]• 4H2O, was proposed on the basis of chemical composition, FT-IR and thermal analyses. The influences of pH, contact time, initial solute concentration and temperature are reported. Various parameters such as the effective diffusion coefficient under different conditions and the activation energy were determined from the graphical representation of the linearized form of the Arrhenius equation. Thermodynamic parameters such as ΔG0, ΔH0 and ΔS0 were also calculated. The numerical value of ΔG0 increased from 7.43 to 9.74 kJ/mol as the temperature was increased from 298 K to 313 K, indicating that the exchange reaction was more favourable at low temperatures. The negative value of ΔH0 (–49.55 kJ/mol) reflected the exothermic nature of the exchange process.
Adsorptive Removal of 2,6-Dichlorophenol from Aqueous Solution by Surfactant-Modified Palygorskite Sorbents: Equilibrium, Kinetics and Thermodynamics
Authors: Wang Xue , Pan Jianming , Guan Wei , Zou Xiaohua , Hu Wei , Yan Yongsheng , Li Chunxiang 
Published: July 2011

Raw palygorskite was modified by the addition of selected surfactants, viz. hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB) and octadecyldimethylbenzyl ammonium chloride (ODBAC). These modified clays were used as sorbents for the adsorptive removal of 2,6-dichlorophenol (2,6-DCP) from aqueous solution. Characterization of the sorbents was achieved by Fourier-transform infrared (FT-IR) analysis, nitrogen adsorption/desorption measurements and particle-size analysis. The adsorptive performance of the modified palygorskites towards the removal of 2,6-DCP from aqueous solution was studied by batch methods. In addition, the influence of contact time, pH and temperature on the adsorption process was investigated in detail. The equilibrium data for the three modified sorbents were well fitted by the Langmuir model. It was found that the monolayer adsorption capacity increased with increasing contact time and solution temperature, respectively. Application of the pseudo-first-order and pseudo-second-order kinetic models to the kinetic data showed that the pseudo-second-order kinetic model provided an excellent fit (R2 > 0.99). In addition, the film diffusion, pore diffusion and intra-particle diffusion models were also used to investigate the adsorption mechanism. Intra-particle diffusional analysis indicated that 2,6-DCP molecules diffused rapidly during the initial adsorption stage, followed by a slower stage and finally the establishment of an equilibrium condition. Thermodynamic studies showed that the adsorption of 2,6-DCP onto the three sorbents examined occurred spontaneously and that the process was endothermic in nature. The results indicate that the surfactant-modified palygorskite exhibited a significant potential as a sorbent material for the removal of phenolic compounds from aqueous solution.
In situ Measurement Methods for Characterising Sound Diffusion
Authors: Schmich I. , Brousse N. 
Published: July 2011

Two methods have been investigated to define a new way of measuring diffusion in situ. The first one is based on the measurement of a mono-dimensional reverberation time between two parallel plates and gives an evaluation of a scattering coefficient. This field method has been tested through computer simulation and shows high sensitivity to experimental conditions. The experimental set-up has been realized and laboratory measurements conducted. The second method is focused on the scale of a concert hall and proposes new parameters which could lead to a new global diffusivity index. It has been simulated with a computer model with various diffuser arrangements. These two methods are complementary and if further developed could lead to efficient tools for evaluating and optimizing diffusion in real concert halls.
Open Measurements of Edge Diffraction from a Noise Barrier Scale Model
Authors: Schröder Dirk , Svensson U. Peter , Vorländer Michael 
Published: July 2011

Until today, all known simulation methods for the wave phenomenon of edge diffraction are just approximations, based on either Geometrical Acoustics or the numerical solving of the wave equation. Although these methods work fine for simple test scenarios and a certain frequency range, they fail to simulate the effect of diffraction in its whole complexity. This leads to false predictions especially for more complex geometries where the influence of multiple wave diffraction and sound scattering has to be taken into account as well. Consequently, huge effort is currently put into the development of improved simulation methods. Here, a basic need is an all-embracing validation of simulation results, which also includes the comparison with real-world measurements. Unfortunately, there is a lack of such data which is the reason why the Institute of Technical Acoustics (ITA), RWTH Aachen University, Germany, and the Centre for Quantifiable Quality of Service in Communication Systems (Q2S), NTNU Trondheim, Norway, have started an initiative called openMeasurements, which is aimed to be an internet platform for free acoustic measurement data of any kind, together with their respective simulation models (CAD-model, detailed information on sources and receivers, material data) and helpful tools. As initial step, various measurement series of a scaled-down model of a noise barrier were carried out. These series aim to give researches, developers, and common application users, the possibility to thoroughly test their prediction models of edge diffraction. The measurements were carried out in a full anechoic chamber and a turntable was used to rotate the scale-model during the measurements in steps of one degree. The scale-model was constructed with a changeable ground layer in order to massively influence the object's acoustical properties and, thus, create measurement datasets that considerably differ. Here, datasets for five different ground layers were obtained: 3 absorbers, 1 rigid surface and 1 self-constructed skyline-diffuser. A skyline diffuser was chosen as it is a well reproducible geometrical pattern, which enables a simulation of sound scattering in two ways: stochastic and deterministic. In this contribution, detailed information on the measurement setup is given and measurement procedures are described thoroughly. Measurement uncertainties are briefly discussed and first comparisons with simulations are presented. All measurements together with geometrical models of the scale-model (with/without diffuser), detailed information on sources and receivers, material data (absorption- and scattering coefficients) and useful Matlab tools are freely available for download ( www.openmeasurements.net ).
Regressing the Size and Cost of Turbulent Cavity Flow Simulations
Authors: Rona A. , Monti M. 
Published: July 2011

A successful model of high Reynolds number cavity flows involves reproducing the flow physics with adequate accuracy, given the available computational resources. The process of planning high Reynolds number cavity flow simulations is systematically reviewed to extract the dependence of different programmer's choices on the CFD mesh size and on the cost of the computation. This process has been broken down into five phases: i) description of the problem in the continuous domain, ii) problem order reduction by turbulence modelling, iii) discretization in space and time, iv) integration of the governing equations, v) costing the numerical operations of the flow solver. This paper examines the influence of each phase on the spectral width and the grid density, which are the key CFD indicators that determine the cost of the computation. A dimensional analysis was conducted to separate the effects of the geometry of the enclosure, the boundary layer resolution, the turbulence model, and the numerical scheme order of accuracy. Regression analysis on the non-dimensional groups of published cavity CFD simulations determined the range of practical values used by current state-of-the-art computations. This analysis is a useful tool for obtaining design trade-offs by a multivariate optimization in cavity flow CFD and for estimating the order of magnitude of the computational resources required by the simulations.
Generating Approximate Inverse Preconditioners for Sparse Matrices Using CUDA and GPGPU
Authors: Xu Shiming , Xue Wei , Wang Ke , Lin Hai Xiang 
Published: July 2011

The problem of numerical solution of sparse matrix-based linear systems arises from many scientific applications. Iterative solvers and corresponding preconditioning techniques are usually adopted. Due to the the irregularity in memory access patterns and undeterministic branching behavior of sparse matrix-based algorithms, they present unique problems for emerging GPU-based platforms. This paper discusses the techniques associated with applying GP-GPU and CUDA to the generation of right-looking approximate inverse preconditioners (AINV) and preconditioned GMRES based on them. Parallel algorithms are designed for generating AINV preconditioners with predefined sparsity pattern or dynamic fill-in control themes. Detailed complexity analysis is provided for dynamic fill-in control in preconditioners. Shared Memory-based optimization yield 200% speedup in the sparse vector inner products and sparse vector updates; while overall speedup compared with parallel CPU-based implementations are 3 times and 6 times, respectively. The preconditioned GMRES iteration based on AINV witnessed 7 to 9 times speedup, due to the high efficiency of matrix-vector product based preconditioning. The developed techniques can also be applied to other Krylov solvers and preconditioners.
Toxicity of Alzheimer's disease-associated Aβ peptide is ameliorated in a Drosophila model by tight control of zinc and copper availability
Authors: Hua Haiqing , Münter Lisa , Harmeier Anja , Georgiev Oleg , Multhaup Gerd , Schaffner Walter 
Published: July 2011

Abstract
Amyloid plaques consisting of aggregated Aβ peptide are a hallmark of Alzheimer's disease. Among the different forms of Aβ, the one of 42aa length (Aβ42) is most aggregation-prone and also the most neurotoxic. We find that eye-specific expression of human Aβ42 in Drosophila results in a degeneration of eye structures that progresses with age. Dietary supplements of zinc or copper ions exacerbate eye damage. Positive effects are seen with zinc/copper chelators, or with elevated expression of MTF-1, a transcription factor with a key role in metal homeostasis and detoxification, or with human or fly transgenes encoding metallothioneins, metal scavenger proteins. These results show that a tight control of zinc and copper availability can minimize cellular damage associated with Aβ42 expression.
Results of the recalibration of creatinine measurement with the modular Beckman Coulter® Jaffe creatinine method
Authors: Fillée Catherine , Vranken Guido , Othmane Myriam , Philippe Marianne , Allaeys Jean-Michel , Courbe Anne , Ruelle Jean-Luc , Peeters Rudy 
Published: July 2011

AbstractSerum creatinine is important for detecting the beginning of a decline in kidney function. The Beckman Coulter Jaffe reagents for measuring creatinine have been standardized to the internationally accepted reference method: isotope dilution mass spectrometry (IDMS). The impact of this recalibration on the Beckman CoulterRecalibrated Jaffe (calibrator set points IDMS traceable) and classic National Institute of Standards and Technology (NIST) creatinine methods (traceable to NIST 914a) were compared with an enzymatic method (Sentinel, traceable to NIST SRM 967). All measurements were performed on Synchron DxC 800 systems. Imprecision of the routine methods was studied using the Clinical and Laboratory Standards Institute (CLSI) protocols and laboratory quality survey. Thirteen plasma pools, with concentrations <354 μmol/L, were analyzed with a gas chromatography isotope dilution mass spectrometry (GC-IDMS) method and routine methods. Total error of 8.2% based on biological variability, set on the GC-IDMS values and acceptance criteria (bias <5%, imprecision <8% at concentrations ≥88.4 μmol/L and a maximum 10% increase in the relative error of estimated glomerular filtration rate (eGFR) of the National Kidney Disease Educational Program (NKDEP) were used for evaluating analytical performance of the routine methods studied.After recalibration of the Jaffe method, median bias (μmol/L) decreased from 12.4 (95% CI: 9.1–21.2) to 7.3 (95% CI: 1.5–10.5). Imprecision of the Jaffe method is in agreement with the claim of the manufacturer, namely <9 μmol/L or <3% below or above 292 μmol/L. Below creatinine of 88.4 μmol/L, imprecision of the recalibrated Jaffe and enzymatic methods is between 4.1% and 6.9%, and 5.0% and 7.1%, respectively, and significantly different (p=0.02 for both the Jaffe and enzymatic methods) from the goal, based on biological variability, of 2.7%. For the adult pools, all recalibrated Jaffe and enzymatic results fall within the total error of 8.2%. In the pediatric samples, one-third of the recalibrated Jaffe and three of the six enzymatic results fall within this total error goal.Recalibration significantly reduced bias of the Jaffe method. For pediatric samples, recalibrated Jaffe results do not comply with either the imprecision goal or the total error based on biological variability. Adult recalibrated Jaffe results are in compliance with the goals based on biological variability and with the acceptance criteria from the NKDEP.
Improvement of dimensional stability of wood via combination treatment: swelling with maleic anhydride and grafting with glycidyl methacrylate and methyl methacrylate
Authors: Li Yongfeng , Wu Qinglin , Li Jian , Liu Yixing , Wang Xiang-Ming , Liu Zhenbo 
Published: July 2011

Abstract
A novel two-step combined treatment of poplar wood was developed to improve its dimensional stability. Maleic anhydride (MAN) was first employed to swell and bond to the wood cell wall, and then mixed monomers of glycidyl methacrylate/methyl methacrylate (GMA/MMA) were grafted to the cell wall through the chemical reaction with MAN within the wood cell lumen. The results of scanning electron microscopy and energy dispersive X-ray apparatus (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR) analyses indicate that MAN penetrated and chemically bonded to the cell wall causing 9% volume swelling, and the copolymer from GMA/MMA monomers was grafted onto the wood cell wall, resulting in the improved interfacial compatibility between the polymer and wood matrix. The dimensional stability of poplar wood modified by the combined two-step treatment was remarkably improved compared with that of untreated poplar wood. The combination treatment of wood employed in this study proved to be more effective for improving the dimensional stability than treatment with PEG-1000 aqueous solution with 30% concentration.
Isolated GH deficiency: mutation screening and copy number analysis of HMGA2 and CDK6 genes
Authors: Gorbenko Del Blanco Darya , de Graaff Laura C G , Posthouwer Dirk , Visser Theo J , Hokken-Koelega Anita C S 
Published: July 2011

ObjectiveIn most patients, the genetic cause of isolated GH deficiency (IGHD) is unknown. By identifying several genes associated with height variability within the normal population, three separate genome-wide association studies provided new candidate genes for human growth disorders. We selected two of them for genetic screening of our IGHD population.AimWe aimed to determine whether high-mobility group A2 (HMGA2) and cyclin-dependent protein kinase 6 (CDK6) are involved in the pathogenicity of IGHD.MethodsWe directly sequenced coding regions and exon–intron boundaries of the genesHMGA2andCDK6in 105 Caucasian IGHD patients from the Dutch HYPOPIT study. In addition, we developed a new probe set of multiplex ligation-dependent probe amplification for both genes in order to detect copy number variations.ResultsIn one patient with classical IGHD phenotype, we identified a new heterozygous 20 bp deletion in the intronic region ofHMGA2(c.250-29_-9del), which was absent in the databases and healthy controls. Together, with recently published data concerning the 12q14 microdeletion syndrome, where patients with anHMGA2haploinsufficiency had proportionate short stature, this study provides further support of the important role for HMGA2 in growth. InCDK6, we found only known polymorphisms.ConclusionsThis study provides the first report of a deletion in theHMGA2gene that might be related to IGHD. We suggest that this gene is investigated as a second screening in patients with a classical IGHD phenotype in which mutations in classical candidate genes have been excluded.
A Robust Approach to Field Development Plan Integrating Multi Dynamic Reservoir Models with Surface Network
Authors: Ojeke Akpoebi , Itotoi Ibiada Harrison , Nnamdi Dike , Umurhohwo Jonathan , Benjamin Osaigbovo 
Published: July 2011

Abstract
Recent advances in computing speed and software call for a better practical approach to subsurface-surface network modelling. Looking at it from the angle of Integrated Asset management, which requires the subsurface and surface teams to work as one in providing input and solution to field development plan challenges, this comes as an important tool in long term planning of a project. With this approach, team members from various disciplines, will be able to work directly with others, sharing ideas and making real time decisions on a regular basis.
The case study in this paper shows how such integration resulted in time and cost savings when good and quick decisions are made on a project. this shows a clear departure from the traditional subsurface/surface engineering relation in field development studies, where the subsurface reservoir simulation work is done independent of surface considerations. This paper highlights the benefits of the new approach to the project.
A Stochastic Approach to Well Spacing Optimization of Oil Reservoirs
Authors: John U. M-P. , Ibukun S. , Pius J. , Kayode O. 
Published: July 2011

Abstract
The subject of well spacing is one of importance in the petroleum industry. The well itself plays a very significant role in the development of the oil and gas reservoirs and in the control of the recovery process. However, determination of appropriate well spacing for maximum economic oil recovery and investment optimization has been a complicated and controversial issue in oil field development.
Previous papers on this subject have concentrated on deterministic evaluation of optimum well spacing to maximize returns on investment. A stochastic approach to fully account for uncertainties in input variables is proposed in this paper.
An analytical approach is used in developing the optimization model from an economic view point. The model is tested with one of the reservoirs of a Niger Delta field. Non-linear programming application is used to estimate the optimum well spacing from a population of input variables of different probability distribution. Uncertainty analysis is carried out using CrystallBall.
The result from the study carried out on the shallow and deep levels of a swamp field located in the Niger Delta, Nigeria gave the optimum well spacing for maximum returns on investment. Unlike the deterministic approach, the stochastic approach provided reasonable bounds for NPV that reflects the uncertainties associated with the input variables.
The optimum well spacing falls within reasonable bounds for field optimization and maximization of returns on investment. The combination of non-linear programming tool and stochastic approach provides a cost effective method in getting a quicker solution to the problem of well spacing.
Advances in Mud Design and Challenges in HPHT Wells
Authors: Godwin Woha , Ogbonna Joel , Boniface Oriji 
Published: July 2011

Abstract
The world's energy demand is rising and favourable economics has allowed oil companies prospect and drill for oil in deeper, more challenging frontiers (which are prone to high pressures and high temperatures) than ever before. There are vast reserves of hydrocarbons in these remote locations that promise to bridge the gap between demand and supply for energy. However HPHT prospects can be a formidable challenge. The mud weight (which is higher for HPHT wells) must be accurately controlled because of the very narrow mud weight windows. This high mud weight requirement leads to problems of high solid loading and barite sag. Technology to effectively monitor downhole pressure and temperature conditions is not well developed. Rig crews need to be adequately trained to adopt best practices in HPHT drilling to minimize the risk of well control issues. In this study, the conventional practices and procedures in mud design were studied and analyzed. Advances in mud design were highlighted and case studies of some HPHT wells in regions around the world were reviewed to learn the lessons and best practices that led to their success. Many of the conventional practices were found to be inadequate for HPHT drilling. Rigorous laboratory testing is necessary to generate detailed engineering guidelines for HPHT drilling fluids. Furthermore, a standard temperature concept used for controlling the surface mud weight was defined. The results of the new approaches to mud design and practices have been phenomenal. The importance of a stable mud system, detailed drilling program, best practices and correct field execution are fundamental. With the new approaches, many HPHT wells have been successfully completed in a cost effective manner and with no well control incidents recorded.
An Approach for Ranking Realizations to Characterize Reservoirs for Fluid Flow Simulation
Authors: Odai Lowestein , Ogbe David O. 
Published: July 2011

Abstract
Techniques in Geostatistics are increasingly being used to generate reservoir models and quantify uncertainty in reservoir properties. This is achieved through the building of multiple realizations to capture significant physical features in the reservoir. However, only a limited number of these realizations are required for complex fluid flow simulation to predict reservoir future performance. Therefore, there is the need to adequately rank and select a few of the realizations for detailed flow simulation.
This paper presents a methodology for building and ranking equiprobable realizations of the reservoir by both static and dynamic measures. Sequential Gaussian Simulation was used to build 30 realizations of the reservoir. The volume of oil originally in place, which is a static measure, was applied in ranking the realizations. Also, this study utilizes Cumulative Recovery and Average Breakthrough times from streamline simulation together with Geometric Average Permeability as the dynamic measures to rank the realizations. A couple of realizations selected from both static and dynamic measures were used to conduct a successful history match of field water cut in a case study.