bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Stage Algebraic Multiscale Linear Solver for Highly Heterogeneous Reservoir Models
Authors: Zhou H.. , Tchelepi H.A.. A. 
Published: February 2012

Summary
An efficient Two-Stage Algebraic Multiscale Solver (TAMS) that converges to the fine-scale solution is described. The first (global) stage is a multiscale solution obtained algebraically for the given fine-scale problem. In the second stage, a local preconditioner, such as the Block ILU (BILU), or the Additive Schwarz (AS) method is used. Spectral analysis shows that the multiscale solution step captures the low-frequency parts of the error spectrum quite well, while the local preconditioner represents the high-frequency components accurately. Combining the two stages in an iterative scheme results in efficient treatment of all the error components associated with the fine-scale problem. TAMS is shown to converge to the reference fine-scale solution. Moreover, the eigenvalues of the TAMS iteration matrix show significant clustering, which is favorable for Krylov-based methods. Accurate solution of the nonlinear saturation equations (i.e., transport problem) requires having locally conservative velocity fields. TAMS guarantees local mass conservation by concluding the iterations with a multiscale finite-volume step. We demonstrate the performance of TAMS using several test cases with strong permeability heterogeneity and large-grid aspect ratios. Different choices in the TAMS algorithm are investigated, including the Galerkin and finite-volume restriction operators, as well as the BILU and AS preconditioners for the second stage. TAMS for the elliptic flow problem is comparable to state-of-the-art algebraic multigrid methods, which are in wide use. Moreover, the computational time of TAMS grows nearly linearly with problem size.
Validation of Toe-to-Heel Air-Injection Bitumen Recovery Using 3D Combustion-Cell Results
Authors: Greaves M.. , Dong L.L.. L. , Rigby S.P. P 
Published: February 2012

Summary
Rigorous validation of a simulation model of the toe-to-heel air-injection (THAI) process has been performed using results obtained from a 3D combustion-cell experiment on Athabasca oil sands. The numerical model includes a new kinetics formulation, based on the Athabasca thermal-cracking kinetics scheme proposed by Phillips et al. (1985). The kinetics model excludes low-temperature oxidation because THAI operates in a high-temperature oxidation mode. Excellent agreement was obtained between the predicted and experimental oil-production rate, and there was generally a good match obtained for other dynamic variables, including the residual coke profile, produced oxygen, and peak combustion temperature. The numerical model provides a fundamental platform for upscaling to field scale that will enable fine-scale details of the process to be captured.
Simulations were performed under dry in-situ combustion (ISC) conditions at the high air-injection fluxes used in the experiment. Under these conditions, vertical-plane temperature profiles in the sandpack confirm that the combustion front is quasivertical and forward leaning in the direction of the heel of the horizontal producer well. The shape of the combustion front was predicted more accurately from horizontal-plane profiles, showing that there was no oxygen in regions ahead of the combustion front. Oil displacement occurs mainly by gravity drainage, but pressure drawdown into the horizontal producer well below the mobile-oil zone (MOZ) is also significant. Various zones that develop during the ISC process include a steam zone located in the upstream part of the MOZ. All of the mobilized oil is produced from the MOZ, which is composed of two distinct oil regions. The first part contains oil produced by thermal cracking of the heavy residue and vaporized lighter oil. The main bulk of the oil produced in THAI comes from the second region of the MOZ, containing banked original oil. The oil that is eventually produced is partially upgraded oil because of the thermally upgraded and lighter oil fractions mixing with the original oil when they enter the horizontal producer well.
Pushing the Boundaries of Concentric-Coiled-Tubing Technology To Resurrect Subhydrostatic Gas Wells on an Unmanned Offshore Installation
Authors: Davies Ann , Dunning Matthew , Kuchel Mike , Roberts Tony , Taggart Michael 
Published: February 2012

Summary
Ravenspurn North is a mature gas field in the southern North Sea with 42 wells, drilled (and many hydraulically fractured) in the late 1980s. By 2006, more than half of the wells had ceased to flow, and many were flowing intermittently. With ailing wells and consequently falling production rates, the longer-term future for Ravenspurn North field was uncertain.
A wireline campaign suggested a common failure mode for many wells: Large amounts of proppant had accumulated in the wellbore. Modeling of the potential range of static and dynamic pressure losses caused by this proppant supported a significant enhancement to the remaining gas potential. However, the depths of the wells combined with subhydrostatic pressure conditions and large-diameter lower completions made achieving cleanout challenging. Furthermore, the target wells were located on unmanned offshore installations with minimal facilities, deck space, and deck loading.
This paper details how each of these obstacles was successfully tackled to reinstate a target set of wells. It describes the various cleanout options that were considered, and why concentric-coiled-tubing vacuum technology (CCTVT) was ultimately selected. Before this project, CCTVT had never been deployed in the North Sea, and nowhere in the world at these reservoir depths. The operation was delivered on the small unmanned installation by conducting the world's first boat-spooling operation of concentric coiled tubing (CCT); rigorously reassessing deck loadings; and running the operation completely self-sufficiently, with a maximum of 10 personnel onboard.
Finally, this paper provides a detailed description of the successful CCTVT operations that recovered a total of 2,950 lbm of proppant from three wells to expose the perforations and unload the wells of liquid. Furthermore, CCT was used to mill out tubing-profile nipples and install a packer to hang off 1,200 ft of flush-joint tail pipe. Innovative thinking and close collaboration between operator and service companies were required, because the ability to perform multiple operations on CCT was in itself pioneering.
Overall, this campaign has pushed the boundaries of intervention technology to deliver an extremely challenging project. This has resulted in a more-certain future for the Ravenspurn North field, as well as newly unlocked opportunities in deep depleted gas wells worldwide.
Modeling and Simulation of Flow Field Around a Blowout Well
Authors: Hajidavalloo Ebrahim , Omidian Parham 
Published: February 2012

Summary
Modeling and simulation of a blowing-out oil/gas well is very important in the drilling industry because they can accurately predict the velocity, pressure, and temperature fields around the well. This would help the personnel during the control operation to make proper decisions with minimum risk. In this paper, hydrodynamics and thermal behavior of a gaseous-well blowout were investigated. The flow was modeled as a free turbulent jet discharging in the atmosphere. A realizable k-ε model was used to model the turbulence, and a non-premixed model was used to model the combustion. The effect of placing a flow tube on the wellhead was studied. The results showed that combustion has an important effect on the flow behavior around the well by doubling the suction flow rate. Using the flow tube has a significant effect by concentrating the vacuum at the bottom of the wellhead, and increasing the flow-tube diameter increases the suction flow rate. It was also found that the drag force on the flow tube will be increased when the flow is reacting or when the flow-tube diameter is increased.
Gas-Well Liquid Loading Probed With Advanced Instrumentation
Authors: Alamu Mhunir Bayonle 
Published: February 2012

Summary
Drop size, liquid holdup, and pressure drop have been measured simultaneously in real time. This experiment was carried out with air/water to establish annular two-phase flow on a 0.019-m-internal-diameter vertical pipe (7-m-long multiphase-flow facility). Drop concentration, distribution, and sizes in the core flow were measured using Spraytec, a light-diffraction-based instrumentation.
Liquid holdup was logged with pairs of flush-mounted ring-conductance probes at various positions within the test section. Pressure drop was monitored using a differential-pressure meter mounted between two pressure taps separated by a distance of 1.5 m.
Subtle changes were observed in the characteristic drop diameters around gas superficial velocities of 21 and 30 m/s following progressive, systematic increase in gas and liquid superficial velocities. The gas superficial velocities at which these changes were observed have been linked with transition boundaries to cocurrent and mist annular flows, respectively. Corresponding similar pseudochanges, fingerprinted in the liquid-holdup and pressure-drop data at these transition boundaries, in addition to film and drop-flow reversals captured on video, make the evidence more compelling. Applicability of core-flow dynamic data to explain various physical processes associated with gas-well liquid loading has been demonstrated.
Occluding Effect of Nd:YAG Laser and Different Dentin Desensitizing Agents on Human Dentinal Tubules In Vitro: A Scanning Electron Microscopy Investigation
Authors: Al-Saud LMS , Al-Nahedh HNA 
Published: February 2012

SUMMARY

Objectives
This in vitro study aimed to microscopically evaluate and compare the occluding effect of the Nd:YAG laser and different dentin desensitizing agents on human dentinal tubules.

Materials and Methods
The Nd:YAG laser (SunLase™ 800) and four commercially available and professionally applied dentin desensitizers (Gluma® desensitizer, Tenure Quick®, Quell™ desensitizer, and VivaSens®) were investigated in this study. Sixty-four extracted intact human molars were used. Each dentin surface was divided by shallow indentation into two halves, one of which was used for treatment and the other of which served as a control. The dentin surfaces were etched to remove any smear plugs and to mimic the open dentinal tubules of sensitive dentin using 0.5 M ethylenediaminetetraacetic acid (pH 7.4) for two minutes (applied with a microbrush) and then rinsed with an air-water syringe for 30 seconds. The laser samples (n=16) were randomly divided into four groups of four samples each. These groups were the step-up technique group, the 14-day group, the one-minute group, and the two-minute group. Forty-eight samples were treated with the four tested desensitizing agents and were randomly divided into four groups (n=12/group). Each group was further subdivided into three subgroups (n=4). Samples of the first subgroup were treated for 14 days, while those of the second subgroup were treated once. Samples of the last subgroup were fractured longitudinally after a single treatment. All of the samples were then examined under a scanning electron microscope.

Results
The Nd:YAG laser–irradiated dentin showed reduction or complete obliteration of the dentinal tubule lumen; thus, the treatment modified the original dentinal structure. The lased dentin surface in the two-minute group showed bubble-like changes in the area of the dentinal tubules' orifices. Statistically, the two-minute group was found to have a significantly higher percentage of partially or fully occluded tubules than did the one-minute group. All of the studied desensitizing agents produced occlusion of the dentinal tubules; however, the appearance of the precipitates, the level of coverage, and the degree of dentinal occlusion varied among the tested products.

Conclusion
Throughout the specified period of this study, occlusion and/or narrowing of the open dentinal tubules have been successfully achieved with both treatment approaches.
Clinical Evaluation of Stress-reducing Direct Composite Restorations in Structurally Compromised Molars: A 2-year Report
Authors: Deliperi S , Bardwell DN , Alleman D 
Published: February 2012

SUMMARY

Objective
To evaluate the clinical performance of class II large-size direct composite restorations.

Materials and Methods
Fifty (50) patients 18 years or older were included in this clinical trial restoring 75 vital molar teeth with large-size cavities.

Inclusion Criteria
Occlusal extension greater than two-thirds the intercuspal distance and proximal extension greater than half the distance between line angles. Teeth with residual cavity walls less than 1 mm and with one or more cusps involved were excluded. Teeth were randomly divided in three groups. Group 1: Opti-Bond FL; group 2: Scotchbond 1 XT; group 3: PQ1. Total-etching was performed using 35% phosphoric acid followed by the application of 2% chlorhexidine gluconate in the three groups. All teeth were restored using Vit-l-escence microhybrid composite resin. The proximal surface was built up first, followed by dentin and enamel occlusal surface stratification; wedge-shaped increments of composite resin were placed and cured using the UltraLume V curing light through a combination of pulse and progressive curing techniques.

Results
Restorations were evaluated at six-month intervals during the two-year period using a modified US Public Health Service criteria by two independent evaluators precalibrated at 85% reliability. No failures were reported and α scores were recorded for all parameters. Statistical analysis was performed using a χ2 test and the Fisher exact test (χ2=10.6; p=0.001). No teeth exhibited sensitivity in the three groups both at the two-week recall and two-year follow-up.
Endothelial cell adhesion on polyelectrolyte multilayer films functionalised with fibronectin and collagen
Authors: Zanina Nahla , Haddad Soumaya , Othmane Ali , Jouenne Thierry , Vaudry David , Souiri Mina , Mora Laurence 
Published: February 2012

AbstractThe seeding of endothelial cells on biomaterial surfaces has become a major challenge to achieve better haemocompatibility of these surfaces. Multilayers of polyelectrolytes formed by the layerby-layer method are promising in this respect. In this study, the interactions of endothelial cells with multilayered polyelectrolytes films were investigated. The build-ups were prepared by selfassembled alternatively adsorbed polyanions and polycations functionalised with fibronectin and collagen. Anionic poly(sodium 4-styrenesulfonate) and cationic poly(allylamine hydrochloride) polyelectrolytes were chosen as a model system. Elaborated surfaces were characterised by electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode showed good reversible electrochemical properties and high stability in an electrolyte solution. The film ohmic resistance was highest when the film was coated with fibronectin; the parameters so determined were correlated with atomic force microscopy images. Cell colorimetric assay (WST-1) and immunofluorescence were used to quantify the cell viability and evaluate the adhesion properties. When cultured on a surface where proteins were deposited, cells adhered and proliferated better with fibronectin than with collagen. In addition, a high surface free energy was favourable to adhesion and proliferation (48.8 mJ m−2 for fibronectin and 39.7 mJ m−2 for collagen, respectively). Endothelial cells seeded on functionalised-polyelectrolyte multilayer films showed a good morphology and adhesion necessary for the development of a new endothelium.
Selective anomeric deacetylation using zinc acetate as catalyst
Authors: Kaya Eda , Sonmez Fatih , Kucukislamoglu Mustafa , Nebioglu Mehmet 
Published: February 2012

AbstractAn alternative method has been developed for the anomeric deacetylation of fully acetylated carbohydrate derivatives using zinc acetate dihydrate as a catalyst in methanol under mild conditions. The experimental simplicity, low cost, acceptable yield, use of a readily handled acidic catalyst, and the environmentally benign nature are some of the advantages of this method.
Solubility of methane in octane + ethanol at temperatures from 303.15 K to 333.15 K and pressures up to 12.01 MPa
Authors: Cai Jun-Qing , Qiao Jin-Zhi 
Published: February 2012

AbstractSolubility of methane in octane + ethanol was measured at temperatures ranging from 303.15 K to 333.15 K and pressures ranging from 2.60 MPa to 12.01 MPa. Experimental data were analyzed using the Soave-Redlich-Kwong equation of state with three types of mixing rules, and the estimated average deviation from the experimental solubility data was less than 3.5 %.
Novel report of expression and function of CD97 in malignant gliomas: correlation with Wilms tumor 1 expression and glioma cell invasiveness
Authors: Chidambaram Archana , Fillmore Helen L. , Van Meter Timothy E. , Dumur Catherine I. , Broaddus William C. 
Published: February 2012

Object
The Wilms tumor 1 (WT1) protein—a developmentally regulated transcription factor—is aberrantly expressed in gliomas and promotes their malignant phenotype. However, little is known about the molecular allies that help it mediate its oncogenic functions in glioma cells.

Methods
The authors used short interfering RNA (siRNA) to suppress WT1 expression in glioblastoma (GBM) cells and evaluated the effect of this on GBM cell invasiveness. Gene expression analysis was then used to identify the candidate genes that were altered as a result of WT1 silencing. One candidate target, CD97, was then selected for further investigation into its role by suppressing its expression using siRNA silencing, followed by proliferation and invasion assays.

Results
WT1 levels were reliably and reproducibly suppressed by siRNA application. This resulted in a significant decrease in cellular invasiveness. Microarray analyses identified the gene products that were consistently downregulated (27) and upregulated (11) with WT1 silencing. Of these, CD97 expression was consistently suppressed across the 3 different GBM cell lines studied and was found on further investigation to significantly impact GBM cell invasiveness.

Conclusions
Although CD97 expression in gliomas has not been described previously, we conclude that the possible upregulation of CD97 mediated by WT1 promotes cellular invasiveness—one of the most characteristic and challenging aspects of glial tumor cells. Further studies are needed to clarify the nature of this regulation and its impact, as CD97 could represent a novel target for antiglioma therapies.
Cluster analysis of submontane forest along western slope of Frasers' Hill Research Centre in Raub District, Malaysia
Authors: Adam Jumaat H , Ming Liow Kah , Juhari Mohd Afiq Aizat , Jalaludin Masdahila Ahmad , Idris Wan Mohd Radzi , Othman ABD Rahim , Tarmidzi Siti Norhafizah Ahmad 
Published: February 2012

Submontance forest at five different altitudes along the western slope of Frasers' Research Centre (FHRC) in Raub District, Pahang State of Malaysia by Ward Linkage Method (WLM) was classified. Five plots were set at 1000 m (P1), 1050 m (P2), 1100 m (P3), 1150 m (P4) and 1200 m (P5), and all the trees with diameter at breast height (DBH) ≥ 5 cm have been measured. Cluster analysis by WLM of these plots resulted in the identification of four forest zones (FZ) denoted by FZ1P1, FZ2P2, FZ3P3P4 and FZ4P5. These forest zones were denoted by three most dominant species in term of importance value (Iv) such as Dacrydium elatum (Roxb.) Wall. ex Hook.- Prunus arborea (Blume) Kalkman - Adinandra dumosa Jack (Zone FZ1P1), Trigonobalanus verticillata Forman - Syzygium stapfianum (King) I.M. Turner - Syzygium subdecussatum (Wall. ex Duthie) I.M. Turner (Zone FZ2P2), Syzygium leptostemon (Korth.) Merr. & L.M. Perry - Wikstroemia polyantha Merr - Syzygium napiforme (Koord. & Valeton) Merr. & L.M. Perry (Zone FZ3P3P4) and Syzygium filiforme (Wall. ex Duthie) P. Chantaranothai & J. Parn.- Decaspermum parviflorum (Lam.) A.J. Scott - Litsea machilifolia Gamble (Zones FZ4P5). Correlation analysis showed that the number of trees in 0.1 ha, density/ha, DBH, mean DBH, number of species, number of family, number of genus, basal area (BA), mean BA, R, H and E and species with the biggest DBH decreased with increasing altitude. The r-values obtained for these 13 attributes were from – 0.13 to – 0.99. The distribution of trees were found to differ between DBH Class (DBHC) in all FZ. This study revealed that 73.1 to 88.17% of trees in all FZ fall into DBHC1 and DBHC2. On the other hand, 1.02 to 6.28% fall into DBHC5, DBHC6 and DBHC7. The distribution of species was different between Iv Class (IvC) all the four FZ. It was found that from 77.68 to 93.75% of the species fall into IvC1 and IvC2, and between 1.66 to 5.12% of the species fall into IvC4 and IvC5. Key words: Cluster analysis; Submontane forest; Western slope; Malaysia DOI: http://dx.doi.org/10.3329/bjb.v40i2.9767 Bangladesh J. Bot. 40(2): 121-132, 2011 (December)
Phenology and degree days of rice cultivars under organic culture
Authors: Islam MR , Sikder S 
Published: February 2012

Variations in the phenology and degree days of five fine rice cultivars viz., Rajshahi swarna, Silkumul, Kataribhog, Lal pajam and Sanla under organic and inorganic cultural conditions were studied following a split plot design. The requirement of days to attain various phenological stages was highest in Rajshahi swarna, medium in Silkumul, Kataribhog and Lal pajam and the lowest in Sanla for both the cultural conditions. The growing degree days (GDD) and heat use efficiency (HUE) were slightly higher under inorganic than organic culture because of higher life span of rice cultivars in inorganic culture. The highest GDD and HUE were found in Rajshahi swarna, whereas the lowest in Sanla. Results also showed that the requirement of days and GDD were initially higher up to maximum tillering stage under organic culture but thereafter these requirements were greater under inorganic culture for all the cultivars. The grain yield was somewhat lower in organic compared to inorganic culture. In Rajshahi highest grain yield of swarna was 2.90 and 2.74 t/ha under inorganic and organic culture, respectively. Key words: Phenology; Growing degree days; Heat use efficiency; Fine rice DOI: http://dx.doi.org/10.3329/bjb.v40i2.9770 Bangladesh J. Bot. 40(2): 149-153, 2011 (December)
Airborne bio-particulate objects at Chittagong University Campus
Authors: Pasha MK , Hossain Mohammad Sohrab 
Published: February 2012

Survey of airborne bio-particulate objects was carried out at Chittagong University Campus during October, 2006 to September, 2007. A total of 1,451 such airborne objects were encountered consisting of plant parts and non-plant parts. Flower parts made the highest contribution, followed by dermal appendages, filamentous objects, fungal spores, plant tissues and insect appendages. Maximum concentration of airborne bio-particulate objects were observed in the month of June and minimum in November. Key words: Airborne particulate objects; Plant parts; Insect appendages; Chittagong University Campus DOI: http://dx.doi.org/10.3329/bjb.v40i2.9776 Bangladesh J. Bot. 40(2): 189-191, 2011 (December)