bluuebunny/crossref_metadata_2025_split huggingface dataset:
"Don't Let the Temperature Log Fool You"—False Indications of Height Containment From Case Studies in a Tectonically Stressed Environment
Authors: Dozier George C. 
Published: June 2009

Summary
Fracture-height prediction and evaluation is critical in understanding the effectiveness of a fracturing treatment. Volumetrically, fracturing must adhere to mass-balance equations. Therefore, prop-pant placed in the fracture must be accounted for in the creation of fracture height, width, and length. In many cases, excessive fracture height generation is at the expense of fracture-width and -length creation. As a result, in fracture treatments where excessive height growth is believed to have occurred, premature screenouts are usually the result of insufficient fracture width. This unfortunate circumstance creates an operational strain and productivity underperformance for wells.
Various methods have been used to evaluate fracture height before the fracture treatment. These methods can be as simple as height estimates based on sensitivity studies of fracture-height growth for different fluids, pumping rates, and other factors, using a derived rock-stress profile within a fracturing simulator, and as complex as the most robust methods of direct measurement, using passive seismic monitoring of fracture events during an injection test. As the industry comes closer to what is believed to be direct measurement of fracture height, the level of trust increases as well.
Both temperature logs and radioactive tracers have been used on a regular basis by the fracturing industry to evaluate fracture-height containment (or the lack thereof). However, the information from these tools may be quite misleading when planning a fracture treatment because of the inherent assumption made when analyzing the log data. The major assumption is of a vertical fracture propagating from the wellbore. Nevertheless, in a tectonically stressed environment, where the maximum principal stress is not always an overburden, the assumption of a vertical fracture may be incorrect. Where this is true, the indication of height control seen in these log types may be a mirage. This paper describes, through case studies, the unique problems of evaluating fracture height in tectonically stressed formations. Furthermore, it shows that while both temperature and tracer logs may add value to evaluating fracture effectiveness, their results should be validated by a thorough pressure analysis of the injection data. If this critical step is forgone, many assumptions of height control, as indicated by a temperature log alone, may in fact conceal an environment of excessive height growth and lead to premature screenouts.
The First Dual-Lateral Well Successfully Drilled Underbalanced in Libya
Authors: Safar Hussein , Azhary Sadek , Hijazi Ahmad , Qutob Hani , Chopty James 
Published: June 2009

Summary
The B24 well in the Fidaa Field was the first dual-lateral, underbalanced horizontal well drilled in Libya and the second well of Zueitina Oil Company's (ZOC) underbalanced drilling (UBD) campaign.
The targeted hard dolomite reservoir, "Facha," is partly depleted after 23 years of production to a 7.2 lbm/gal equivalent mud weight. Nitrified diesel, a two-phase drilling fluid, was used to drill the reservoir section of the B24 well underbalanced to avoid circulation losses and formation damage. Real-time logging while drilling (LWD) was crucial for geosteering the well path in a complex reservoir structure, and real-time annular-pressure measurement also was necessary to ensure that the underbalanced condition was maintained throughout the entire UBD phase.
Two 6-in. horizontal drains were drilled successfully with 2,053- and 1,517-ft drain lengths. Integrated efforts of ZOC and service companies of various disciplines during planning and operation stages of the well led to the success of the project. No quality, health, safety, and environment (QHSE) incidents were reported, and the productivity of the well was enhanced significantly (Cade et al. 2003; Qutob 2004a).
The B24 well's production alone contributes more than 30% of the total Fidaa field production.
The high-temperature creep properties of materials processed using severe plastic deformation
Authors: Xu Cheng , Kawasaki Megumi , Langdon Terence G. 
Published: June 2009

Abstract
Processing through the application of severe plastic deformation (SPD) is now an accepted procedure for introducing very significant grain refinement into bulk solids. Typically, experiments show that the materials processed in this way have grain sizes in the submicrometer or even the nanometer range. This exceptional grain refinement provides an opportunity for conducting creep tests at elevated temperatures and examining the occurrence of creep flow through mechanisms where the creep rate varies inversely with the grain size. The present paper describes creep experiments conducted on two different representative materials subjected to SPD processing: high-purity aluminum and an aluminum 7034 alloy. The results demonstrate that the creep behavior depends critically upon the thermal stability of the ultrafine-grain microstructures.
The elastic–plastic transition in nanograined polycrystals
Authors: Saada Georges , Dirras Guy 
Published: June 2009

Abstract
This paper is devoted to the analysis of the specific constraints imposed on the mean free path, the nucleation and the multiplication rate of dislocations in strained polycrystals whose grain size is smaller than about 100 nanometres. It is demonstrated that the extent of the microdeformation stage, at the end of which the yield stress should be measured, is definitely larger than the generally accepted value of 0.2 % proof strain for average grain sizes smaller than 125 nanometres. This analysis is confirmed experimentally in two instances. Systematic experimental analysis of the elastic – plastic transition in these materials is a necessary requirement in order to obtain relevant values of the flow stress in these materials.
Effect of equal channel angular pressing on microstructure, texture, and high-cycle fatigue performance of wrought magnesium alloys
Authors: Müller Julia , Janeček Miloš , Yi Sangbong , Čížek Jakub , Wagner Lothar 
Published: June 2009

Abstract
The magnesium alloys AZ80 und ZK60 received from Dead Sea Magnesium in as-cast conditions were extruded at T = 350 °C using an extrusion ratio of ER = 22. The extruded bars were severely plastically deformed by equal channel angular pressing (ECAP). Multiple ECAP processing up to 8 passes was done. The ECAP-induced changes in grain size and grain size distribution were measured by transmission electron microscopy while changes in dislocation density and crystallographic textures were determined by positron annihilation spectroscopy and X-ray diffraction analysis, respectively. The strain induced by ECAP was found to influence the microstructural characteristics, in particular the grain size, the dislocation density, and the crystallographic texture, which in turn enhance (or deteriorate) the mechanical or fatigue response of both alloys.
Deformation behaviour of ultrafine-grained 7075 aluminium alloy
Authors: Lukáč Pavel , Turba Kryštof , Málek Přemysl , Cieslar Miroslav 
Published: June 2009

Abstract
Samples of a 7075 aluminium alloy were prepared by the equal-channel angular pressing (ECAP) technique. The channel had a 10 mm × 10 mm cross section and an angle of 90°. A total of six passes was performed using route BC. The ECAP processing was carried out at 120, 170, and 220 °C. The ECAP-processed samples with grain sizes between 300 and 2000 nm were machined to tensile specimens with their tensile axis parallel to the pressing direction. Uniaxial tensile tests were carried out using an INSTRON testing machine at temperatures between room temperature and 300 °C at a constant crosshead speed giving an initial strain rate of 10 – 3 s – 1. The maximum stress decreases with increasing testing temperature. The elongation to failure increases with increasing testing temperature. The values of the yield stress, the maximum stress (ultimate tensile stress), and the elongation to failure depend also on the ECAP processing conditions.
Recovery and recrystallization behavior of aluminum processed by extrusion-preceded equal channel angular pressing
Authors: Zi Aikaterini , Stulíková Ivana , Smola Bohumil , Riehemann Werner 
Published: June 2009

Abstract
High-purity aluminum was severely plastically deformed by miniaturized extrusion-preceded ECAP as well as by cold rolling. Isochronal and isothermal annealing was performed to investigate the recovery and recrystallization behavior by measuring the development of Vickers microhardness and electrical resistivity. Both processes were found to take place which was verified by TEM and EBSD observations. The onset and course of recovery and recrystallization in cold-rolled Al were postponed to higher temperatures and time due to the lower stored deformation energy. The activation energies for recovery and recrystallization estimated from the microhardness response to isothermal annealing match well those of relevant processes, namely those of thermally activated dislocation motion, pipe-, boundary-, and self-diffusion.
EBSD investigation of the grain boundary distributions in ultrafine-grained Cu and Cu–Zr polycrystals prepared by equal-channel angular pressing
Authors: Dopita Milan , Janeček Miloš , Rafaja David , Uhlíř Jaromír , Matěj Zdeněk , Kužel Radomír 
Published: June 2009

Abstract
Ultrafine-grained copper and cooper–zirconium polycrystals prepared by equal-channel angular pressing following the route Bc to various strain (1, 2, 4 and 8 passes) were investigated using electron back-scatter diffraction. Equal-channel angular pressing resulted in significant grain-size reduction. The original course-grained structure evolved from prolate bands of cells/subgrains enclosed by lamellar nonequilibrium grain boundaries (after the first two passes) towards an equiaxed homogeneous microstructure with equilibrium grain boundaries (after 8 passes). Significant changes in the volume fraction and the character of grain boundaries were observed both in Cu and in Cu – Zr alloy. Pronounced evolution of twin-related boundaries (3n grain boundaries) with strain (number of ECAP passes) was found in Cu while only a weak increase of 3 and 9 grain boundaries was observed in Cu – Zr alloys.
XRD profile analysis of ECAP Cu and Cu + Zr samples
Authors: Matěj Zdeněk , Kužel Radomír , Dopita Milan , Janeček Miloš , Čížek Jakub , Brunátová Tereza 
Published: June 2009

Abstract
Technical purity copper and copper with addition of 0.18 wt.% of zirconium samples processed by equal channel angular pressing with different number of passes were studied by X-ray line profile analysis. Dislocation-induced broadening is the dominant effect determining diffraction line shape. X-ray analysis reveals increasing mean dislocation density (∼1015 m – 2) with the number of ECAP passes. The character of the deformation field connected with the dislocation distribution is slightly different in pure copper than in copper with addition of zirconium and evolves significantly during 4 or 8 ECAP passes in the case of pure copper.
Effects of shot peening on internal friction in cp aluminum and aluminum alloy 6008
Authors: Flejszar Aneta , Ludian Tomasz , Mielczarek Agnieszka , Riehemann Werner , Wagner Lothar 
Published: June 2009

Abstract
The strain-amplitude-dependent damping of bending beams of aluminum alloy 6008 and CP aluminum was measured at room temperature after different heat treatments and after shot peening. Shot peening led to an increase of damping in almost the whole measured amplitude strain range from 10 – 6 to 10 – 3 for CP aluminum. Strong ageing effects at room temperature were observed immediately after the shot peening process, namely an increase of the amplitude dependent part and a decrease of the amplitude-independent part of damping. After about 2700 h, ageing of the samples had saturated. For aluminum alloy 6008 much smaller ageing effects were found being due to compensating effects like formation of Cottrell clouds, precipitation of G.P. – zones, and the reduction of foreign atoms in solid solution. The found amplitude-dependent damping can be explained by the reversible movement of dislocations between strong pinning points like, e. g., precipitates and weak pinning points like solid solute atoms as proposed by the dislocation damping theory of Granato and Lücke. Using this model the found ageing effects can be explained by the diffusion of solid solute atoms to the dislocations.
High-temperature creep properties of Fe–Al alloys modified by Zr
Authors: Karlík Miroslav , Kratochvíl Petr , Pešička Josef , Vlasák Tomáš 
Published: June 2009

Abstract
Two Fe – Al alloys with Zr additions were prepared by vacuum induction melting and rolling at 1200 °C: a disordered (ferrite – A2) and a D03-ordered one. The data are compared to a similar Fe3Al-based alloy with lower Zr content investigated earlier. Tensile and creep tests were performed at 600, 700, and 800 °C, where the disordered alloy maintains its A2 structure, and D03-ordered alloys are transformed to B2-ordered structure. Transmission electron microscopy of the alloys crept at 600 °C showed precipitation of fine particles on dislocations, subgrain boundaries and also in the matrix. Coarsening of these particles during creep at 800 °C takes place. The particles in Fe3Al-based alloys are identified mostly as zirconium carbides, whereas (Fe, Al)2Zr precipitates were observed in the ferritic alloy. The increase of Zr content from 0.25 to 0.6 at.% does not have a significant effect on the high temperature (HT) mechanical properties of the Fe3Al-type aluminide, because both alloys contain the same amount of carbon. In consequence no additional volume fraction of ZrC particles could be formed. The creep resistance of the ferritic alloy is considerably lower, but this material can easily be rolled to prepare sheets for HT corrosion protection.
High-pressure torsion deformation of a magnesium-based nanocomposite
Authors: Száraz Zoltán , Trojanová Zuzanka , Zehetbauer Michael 
Published: June 2009

Abstract
Discs of microcrystalline magnesium reinforced with Al2O3 nanoparticles were deformed by high-pressure torsion at room temperature. Hydrostatic pressures from 1 to about 4 GPa were used and discs were deformed from 0.5 up to 2 rotations. The in-situ flow stress curves were obtained and transformed into resolved shear stress/resolved shear strain curves. In-situ stress – strain curves indicate some softening effects, which probably arise from recrystallisation. The evolution of microstructure was observed with methods of light microscopy and transmission electron microscopy. Radial dependence of the microstructure was also monitored with microhardness measurements. The high-pressure torsion deformation also affects the distribution of the reinforcing particles in the hexagonal matrix.
Seroprevalence of Hepatitis C Virus in HIV/AIDS Patients in Jos, Nigeria
Authors: Nimzing Lohya , Busari Bisayo , Ladep Nimzing G 
Published: June 2009

Introduction: Hepatitis C Virus (HCV) infection is a life threatening infection and is more serious in people living with HIV/AIDS (PLWHA). It leads to liver damage more quickly and may also affect the treatment of HIV infection. This study was aimed at determining the seroprevalence of HCV, possible risk factors for HCV infection and highlighting the importance of HCV screening in PLWHA in Jos, Nigeria. Materials and Methods: One hundred and eighty two blood samples were collected from confirmed HIVpositive patients attending clinics at the Faith Alive Hospital in Jos for the detection of anti-hepatitis C antibodies. An enzyme linked immunosorbent assay (ELISA), DIALABTM HCV Ab test kit (DIALAB GmbH, Australia) was used for the analysis. Results: Sixty one of the 182 samples tested positive giving a co-infection rate of 33.9%. Old age and low educational levels of the patients were found to be associated with HCV/HIV co-infection (P<0.05). However, the patient's occupation and marital status and the possible risk factors analyzed which included: histories of blood transfusion, sexually transmitted infection (STIs) apart from HIV, surgery, multiple sex partners and injecting drug use were not associated with HCV infection (P>0.05) for the subjects screened. Also, the CD4 cell count ranges of patients and the use of antiretroviral therapy were not associated with HCV infection (P>0.05). Conclusion: The high HCV/HIV co-infection rate observed indicates a possible increase in the development of chronic liver diseases and hepatocellular carcinoma in these patients. Therefore, increasing education on HCV infection and routine screening of HIV patients for anti-HCV antibodies is critical. Key words: Hepatitis C virus, people living with HIV/AIDS (PLWHA), anti-hepatitis C antibodies, chronic liver diseases, hepatocellular carcinoma. doi: 10.3329/blj.v1i1.2622 Bangladesh Liver Journal Vol.1(1) 2009 p.28-33
Absence ofMycobacterium tuberculosisin Arterial Lesions from Patients with Takayasu’s Arteritis
Authors: ARNAUD LAURENT , CAMBAU EMMANUELLE , BROCHERIOU ISABELLE , KOSKAS FABIEN , KIEFFER EDOUARD , PIETTE JEAN-CHARLES , AMOURA ZAHIR 
Published: June 2009

Objective.Previous studies have suggested thatMycobacterium tuberculosis(MT) could be involved in the pathogenesis of Takayasu’s arteritis (TA). The search for MT in arterial lesions of TA has never been assessed directly by sensitive methods. Our aim was to assess the presence of MT in arterial samples obtained in patients with TA.Methods.Fresh arterial samples were collected from 10 consecutive patients (9 women and 1 man, median age 42 yrs, range 19–67 yrs) with a diagnosis of TA according to the American College of Rheumatology criteria who underwent vascular surgical procedures for their disease. Three patients had recent onset of TA and 7 had longstanding disease. No patient had evidence of active tuberculosis. Arterial biopsies were collected during vascular surgical procedures, and were systematically studied by a pathologist specializing in vascular diseases. Presence of MT was assessed in the biopsies by acid-fast and auramine-fluorochrome stainings, mycobacterial cultures, and direct amplification test (DAT) for MT.Results.Histological examination showed active (n = 5) and inactive (n = 5) arterial lesions. MT was not detected in arterial lesions of either active or inactive TA, by acid-fast and auramine-fluorochrome staining, mycobacterial cultures, or DAT. No DAT inhibitors were found.Conclusion.Our study does not support a direct role of MT in the pathogenesis of arterial lesions in either recent or longstanding TA, but does not exclude the possibility of a cross-reaction between mycobacterial and arterial antigens.
Changes in Lipid Profile Between Flare and Remission of Patients with Systemic Lupus Erythematosus: A Prospective Study
Authors: URQUIZU-PADILLA MARIA , BALADA EVA , CHACON PILAR , PÉREZ EDUARDO HERMOSILLA , VILARDELL-TARRÉS MIQUEL , ORDI-ROS JOSEP 
Published: June 2009

Objective.To determine the lipid profile of patients with systemic lupus erythematosus (SLE) according to the disease activity, and to calculate the percentage of patients that diverged from optimal values.Methods.Serum was collected from 52 patients with SLE at flare and at remission. SLE disease activity was measured by using the SLE Disease Activity Index (SLEDAI). Clinical and biological measures were evaluated in both situations. Total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), and triglyceride (TG) levels were analyzed after overnight fasting. We also calculated the atherogenic ratios of TC/HDLC and LDLC/HDLC.Results.SLE patients had significantly higher median TC/HDLC and LDLC/HDLC ratios at flare than during remission: 4.5 ± 1.5 versus 3.9 ± 1.0 (p = 0.007) and 2.7 ± 1.1 versus 2.4 ± 0.8 (p = 0.015), respectively. The differences persisted after adjustments based on kidney disease and treatment but not after adjusting by creatinine clearance < 60 ml/min/1.73 m2in remission. The variation between flare and remission of the percentage of SLE patients with high-risk levels of lipid profile to desirable values, and vice versa, was statistically significant for the LDLC/HDLC ratio (9 vs 1; p = 0.021).Conclusion.Our results reflect a higher risk of atherosclerosis phenomena in SLE patients during flare than during clinical remission. This might explain the propensity to develop coronary heart disease in patients with SLE.
Serum Uric Acid Is Independently Associated with Metabolic Syndrome in Subjects with and without a Low Estimated Glomerular Filtration Rate
Authors: SEE LAI-CHU , KUO CHANG-FU , CHUANG FANG-HSIU , LI HONG-YI , CHEN YU-MING , CHEN HUNG-WEI , YU KUANG-HUI 
Published: June 2009

Objective.The relationship among serum uric acid (SUA), metabolic syndrome, and chronic kidney disease (CKD) is unclear. We examined whether SUA level is an independent risk factor for chronic kidney disease and whether the association between SUA and metabolic syndrome is affected by kidney function.Methods.We analyzed 28,745 subjects (17,478 men, 11,267 women, age 20–49 yrs) who underwent health examinations at this hospital between 2000 and 2007. Hyperuricemia was defined as SUA level > 7.7 mg/dl in men or > 6.6 mg/dl in women. Kidney function was assessed by estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease Study equation modified for Chinese subjects. Impaired renal function with low GFR was defined as eGFR < 90 ml/min/1.73 m2. The UA-low GFR groups were defined according to the observed combination of hyperuricemia and low GFR: Group A (absence of both hyperuricemia and low GFR); Group B (presence of low GFR but no hyperuricemia); Group C (presence of hyperuricemia but not low GFR); and Group D (presence of both hyperuricemia and low GFR).Results.The prevalence of hyperuricemia, metabolic syndrome, and impaired kidney function with low GFR was 20.3% (27.6% in men, 8.9% in women), 7.6% (10.6% in men, 3.0% in women), and 9.9% (11.6% in men, 7.1% in women), respectively. The Pearson correlation between SUA and eGFR was only −0.26 (−0.21 in men, −0.22 in women; p < 0.001). In men, the age-adjusted odds ratio (OR) of metabolic syndrome was 1.41 (Group B), 2.45 (Group C), and 2.58 (Group D) in comparison with Group A. In women, the age-adjusted OR of metabolic syndrome was 0.83 (Group B), 5.47 (Group C), and 3.31 (Group D) in comparison with Group A.Conclusion.Hyperuricemia is prevalent in the Taiwan population. Hyperuricemia is only weakly associated with renal function, but is strongly associated with metabolic syndrome with or without a low eGFR.