bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-Term Effect of Docosahexaenoic Acid Feeding on Lipid Composition and Brain Fatty Acid-Binding Protein Expression in Rats
Authors: Elsherbiny Marwa , Goruk Susan , Monckton Elizabeth , Richard Caroline , Brun Miranda , Emara Marwan , Field Catherine , Godbout Roseline
Published: October 2015

Arachidonic (AA) and docosahexaenoic acid (DHA) brain accretion is essential for brain development. The impact of DHA-rich maternal diets on offspring brain fatty acid composition has previously been studied up to the weanling stage; however, there has been no follow-up at later stages. Here, we examine the impact of DHA-rich maternal and weaning diets on brain fatty acid composition at weaning and three weeks post-weaning. We report that DHA supplementation during lactation maintains high DHA levels in the brains of pups even when they are fed a DHA-deficient diet for three weeks after weaning. We show that boosting dietary DHA levels for three weeks after weaning compensates for a maternal DHA-deficient diet during lactation. Finally, our data indicate that brain fatty acid binding protein (FABP7), a marker of neural stem cells, is down-regulated in the brains of six-week pups with a high DHA:AA ratio. We propose that elevated levels of DHA in developing brain accelerate brain maturation relative to DHA-deficient brains.
Antioxidant and Anti-Fatigue Constituents of Okra
Authors: Xia Fangbo , Zhong Yu , Li Mengqiu , Chang Qi , Liao Yonghong , Liu Xinmin , Pan Ruile
Published: October 2015

Okra (Abelmoschus esculentus (L.) Moench), a healthy vegetable, is widely spread in tropical and subtropical areas. Previous studies have proven that okra pods possess anti-fatigue activity, and the aim of this research is to clarify the anti-fatigue constituents. To achieve this, we divided okra pods (OPD) into seeds (OSD) and skins (OSK), and compared the contents of total polysaccharides, total polyphenols, total flavonoids, isoquercitrin, and quercetin-3-O-gentiobiose and the antioxidant activity in vitro and anti-fatigue activity in vivo between OSD and OSK. The contents of total polyphenols and total polysaccharides were 29.5% and 14.8% in OSD and 1.25% and 43.1% in OSK, respectively. Total flavonoids, isoquercitrin and quercetin-3-O-gentiobiose (5.35%, 2.067% and 2.741%, respectively) were only detected in OSD. Antioxidant assays, including 1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, ferric reducing antioxidant power (FRAP) and reducing power test, and weight-loaded swimming test showed OSD possessed significant antioxidant and anti-fatigue effects. Moreover, biochemical determination revealed that that anti-fatigue activity of OSD is caused by reducing the levels of blood lactic acid (BLA) and urea nitrogen (BUN), enhancing hepatic glycogen storage and promoting antioxidant ability by lowering malondialdehyde (MDA) level and increasing superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) levels. These results proved okra seeds were the anti-fatigue part of okra pods and polyphenols and flavonoids were active constituents.
Effect of the Network Structure and Programming Temperature on the Shape-Memory Response of Thiol-Epoxy “Click” Systems
Authors: Belmonte Alberto , Guzmán Dailyn , Fernández-Francos Xavier , De la Flor Silvia
Published: October 2015

This paper presents a new methodology to develop “thiol-epoxy” shape-memory polymers (SMPs) with enhanced mechanical properties in a simple and efficient manner via “click” chemistry by using thermal latent initiators. The shape-memory response (SMR), defined by the mechanical capabilities of the SMP (high ultimate strength and strain), the shape-fixation and the recovery of the original shape (shape-recovery), was analyzed on thiol-epoxy systems by varying the network structure and programming temperature. The glass transition temperature (Tg) and crosslinking density were modified using 3- or 4- functional thiol curing agents and different amounts of a rigid triglycidyl isocyanurate compound. The relationship between the thermo-mechanical properties, network structure and the SMR was evidenced by means of qualitative and quantitative analysis. The influence of the programming temperature (Tprog) on the SMR was also analyzed in detail. The results demonstrate the possibility of tailoring SMPs with enhanced mechanical capabilities and excellent SMR, and intend to provide a better insight into the relationship between the network structure properties, programming temperature and the SMR of unconstrained (stress-free) systems; thus, making it easier to decide between different SMP and to define the operative parameters in the useful life.
Associations among Spirituality, Health-Related Quality of Life, and Depression in Pre-Dialysis Chronic Kidney Disease Patients: An Exploratory Analysis in Thai Buddhist Patients
Authors: Saisunantararom Waraporn , Cheawchanwattana Areewan , Kanjanabuch Talerngsak , Buranapatana Maliwan , Chanthapasa Kornkaew
Published: October 2015

There are numerous studies of quality of life (QOL) in chronic kidney disease (CKD) patients; however, there are a few studies of spirituality and its association with QOL. Previous studies were done focusing on Western cultures; thus, the study of CKD patients in Eastern cultures would reveal interesting insights. This study was conducted to explore the spirituality, QOL, and depression of Thai CKD patients, and the associations between spirituality, QOL, and depression. This cross-sectional descriptive study using structured questionnaires was approved by the Khon Kaen University Ethics Committee in Human Research, Thailand. A total of 63 pre-dialysis CKD stage V patients who visited the kidney diseases clinic as appointed at the outpatient department in a community hospital in northeastern Thailand were recruited. The patients were asked for consent and then interviewed. Spirituality was assessed by using the WHOQOL Spirituality, Religiousness and Personal Beliefs (WHOQOL-SRPB) and the Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being Scale (FACIT-Sp). The 9-item Thai Health Status Assessment Instrument (9-THAI) was used to assess QOL. The Beck Depression Inventory-II (BDI-II) was used to evaluate the depression. The study patients had high WHOQOL-SRPB and FACIT-Sp spirituality scores (median = 18.0, and 44.0, respectively). The 9-THAI QOL scores were within the normal range of the Thai general, healthy population (physical health score [PHS]; median = 48.0, mental health score [MHS]; median = 32.0). Based on BDI-II scores, most patients were in the minimal depression group (63.5%). The Spearman rho correlation coefficients (rs) of PHS and WHOQOL-SRPB and FACIT-Sp were moderate with 0.34 for both spirituality measures. Similarly, also the mental health scores (MHS) correlated moderately with WHOQOL-SRPB (rs = 0.46) and FACIT-Sp (rs = 0.37). Depressive symptoms (BDI-II) strongly negatively correlated with WHOQOL-SRPB (rs = −0.58) and FACIT-Sp (rs = −0.55). Overall results were consistent with previous studies in Western contexts. Understanding spirituality would lead to the better management of depression and improving patient survival. These significant associations suggest that further research is needed on how provider knowledge of patient spirituality could affect the outcomes for patients both in terms of depression and patient survival.
Integrating Industrial Ecology Thinking into the Management of Mining Waste
Authors: Lèbre Éléonore , Corder Glen
Published: October 2015

Mining legacies are often dominated by large waste facilities and their associated environmental impacts. The most serious environmental problem associated with mine waste is heavy metals and acid leakage through a phenomenon called acid mine drainage (AMD). Interestingly, the toxicity of this leakage is partly due to the presence of valuable metals in the waste stream as a result of a diversity of factors influencing mining operations. A more preventive and recovery-oriented approach to waste management, integrated into mine planning and operations, could be both economically attractive and environmentally beneficial since it would: mitigate environmental impacts related to mine waste disposal (and consequently reduce the remediation costs); and increase the resource recovery at the mine site level. The authors argue that eco-efficiency and resilience (and the resulting increase in a mine’s lifetime) are both critical—yet overlooked—characteristics of sustainable mining operations. Based on these arguments, this paper proposes a framework to assist with identification of opportunities for improvement and to measure this improvement in terms of its contribution to a mine’s sustainability performance.
Integration of Concentration-Area Fractal Modeling and Spectral Angle Mapper for Ferric Iron Alteration Mapping and Uranium Exploration in the Xiemisitan Area, NW China
Authors: Qiu Jun-Ting , Zhang Chuan , Hu Xiao
Published: October 2015

The high-grade uranium deposits in the Xiemisitan area, northwestern China, are genetically associated with the faulting of felsic volcanic or sub-volcanic rocks. Ferric iron alteration indicates that oxidizing hydrothermal fluids percolated through the rocks. In this study, we measured the gamma-ray intensities of rocks in the Xiemisitan area and we propose a hybrid method for the mapping of ferric iron alteration using concentration-area fractal modeling and spectral angle mapper. The method enables ferric iron alteration to be distinguished from potash-feldspar granitic rocks. The mapping results were integrated with structural data to assist with exploration for uranium in the study area. Using this approach, six prospective areas of mineralization were proposed. Of these areas, two anomalies with high gamma-ray intensities of 104 and 650 Uγ were identified and verified by field inspection. These observations suggest that Enhanced Thematic Mapper Plus images are a valuable tool that can improve the efficiency of uranium exploration.
Measurement Properties of the Smartphone-Based B-B Score in Current Shoulder Pathologies
Authors: Pichonnaz Claude , Duc Cyntia , Gleeson Nigel , Ancey Céline , Jaccard Hervé , Lécureux Estelle , Farron Alain , Jolles Brigitte , Aminian Kamiar
Published: October 2015

This study is aimed at the determination of the measurement properties of the shoulder function B-B Score measured with a smartphone. This score measures the symmetry between sides of a power-related metric for two selected movements, with 100% representing perfect symmetry. Twenty healthy participants, 20 patients with rotator cuff conditions, 23 with fractures, 22 with capsulitis, and 23 with shoulder instabilities were measured twice across a six-month interval using the B-B Score and shoulder function questionnaires. The discriminative power, responsiveness, diagnostic power, concurrent validity, minimal detectable change (MDC), minimal clinically important improvement (MCII), and patient acceptable symptom state (PASS) were evaluated. Significant differences with the control group and significant baseline—six-month differences were found for the rotator cuff condition, fracture, and capsulitis patient groups. The B-B Score was responsive and demonstrated excellent diagnostic power, except for shoulder instability. The correlations with clinical scores were generally moderate to high, but lower for instability. The MDC was 18.1%, the MCII was 25.2%, and the PASS was 77.6. No floor effect was observed. The B-B Score demonstrated excellent measurement properties in populations with rotator cuff conditions, proximal humerus fractures, and capsulitis, and can thus be used as a routine test to evaluate those patients.
Observability Analysis of DVL/PS Aided INS for a Maneuvering AUV
Authors: Klein Itzik , Diamant Roee
Published: October 2015

Recently, ocean exploration has increased considerably through the use of autonomous underwater vehicles (AUV). A key enabling technology is the precision of the AUV navigation capability. In this paper, we focus on understanding the limitation of the AUV navigation system. That is, what are the observable error-states for different maneuvering types of the AUV? Since analyzing the performance of an underwater navigation system is highly complex, to answer the above question, current approaches use simulations. This, of course, limits the conclusions to the emulated type of vehicle used and to the simulation setup. For this reason, we take a different approach and analyze the system observability for different types of vehicle dynamics by finding the set of observable and unobservable states. To that end, we apply the observability Gramian approach, previously used only for terrestrial applications. We demonstrate our analysis for an underwater inertial navigation system aided by a Doppler velocity logger or by a pressure sensor. The result is a first prediction of the performance of an AUV standing, rotating at a position and turning at a constant speed. Our conclusions of the observable and unobservable navigation error states for different dynamics are supported by extensive numerical simulation.
Sensors for Highly Toxic Gases: Methylamine and Hydrogen Chloride Detection at Low Concentrations in an Ionic Liquid on Pt Screen Printed Electrodes
Authors: Murugappan Krishnan , Silvester Debbie
Published: October 2015

Commercially available Pt screen printed electrodes (SPEs) have been employed as possible electrode materials for methylamine (MA) and hydrogen chloride (HCl) gas detection. The room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) was used as a solvent and the electrochemical behaviour of both gases was first examined using cyclic voltammetry. The reaction mechanism appears to be the same on Pt SPEs as on Pt microelectrodes. Furthermore, the analytical utility was studied to understand the behaviour of these highly toxic gases at low concentrations on SPEs, with calibration graphs obtained from 10 to 80 ppm. Three different electrochemical techniques were employed: linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV), with no significant differences in the limits of detection (LODs) between the techniques (LODs were between 1.4 to 3.6 ppm for all three techniques for both gases). The LODs achieved on Pt SPEs were lower than the current Occupational Safety and Health Administration Permissible Exposure Limit (OSHA PEL) limits of the two gases (5 ppm for HCl and 10 ppm for MA), suggesting that Pt SPEs can successfully be combined with RTILs to be used as cheap alternatives for amperometric gas sensing in applications where these toxic gases may be released.
Dynamic Strain Measurements on Automotive and Aeronautic Composite Components by Means of Embedded Fiber Bragg Grating Sensors
Authors: Lamberti Alfredo , Chiesura Gabriele , Luyckx Geert , Degrieck Joris , Kaufmann Markus , Vanlanduit Steve
Published: October 2015

The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used to analyze the vibration characteristics of two real-life composite components. The first component is a carbon fiber-reinforced polymer automotive control arm; the second is a glass fiber-reinforced polymer aeronautic hinge arm. The modal parameters of both components were estimated by processing the FBG signals with two interrogation techniques: the maximum detection and fast phase correlation algorithms were employed for the demodulation of the FBG signals; the Peak-Picking and PolyMax techniques were instead used for the parameter estimation. To validate the FBG outcomes, reference measurements were performed by means of a laser Doppler vibrometer. The analysis of the results showed that the FBG sensing capabilities were enhanced when the recently-introduced fast phase correlation algorithm was combined with the state-of-the-art PolyMax estimator curve fitting method. In this case, the FBGs provided the most accurate results, i.e., it was possible to fully characterize the vibration behavior of both composite components. When using more traditional interrogation algorithms (maximum detection) and modal parameter estimation techniques (Peak-Picking), some of the modes were not successfully identified.
APFiLoc: An Infrastructure-Free Indoor Localization Method Fusing Smartphone Inertial Sensors, Landmarks and Map Information
Authors: Shang Jianga , Gu Fuqiang , Hu Xuke , Kealy Allison
Published: October 2015

The utility and adoption of indoor localization applications have been limited due to the complex nature of the physical environment combined with an increasing requirement for more robust localization performance. Existing solutions to this problem are either too expensive or too dependent on infrastructure such as Wi-Fi access points. To address this problem, we propose APFiLoc—a low cost, smartphone-based framework for indoor localization. The key idea behind this framework is to obtain landmarks within the environment and to use the augmented particle filter to fuse them with measurements from smartphone sensors and map information. A clustering method based on distance constraints is developed to detect organic landmarks in an unsupervised way, and the least square support vector machine is used to classify seed landmarks. A series of real-world experiments were conducted in complex environments including multiple floors and the results show APFiLoc can achieve 80% accuracy (phone in the hand) and around 70% accuracy (phone in the pocket) of the error less than 2 m error without the assistance of infrastructure like Wi-Fi access points.
Effects of Land Use and Slope Gradient on Soil Erosion in a Red Soil Hilly Watershed of Southern China
Authors: Zhang Zhanyu , Sheng Liting , Yang Jie , Chen Xiao-An , Kong Lili , Wagan Bakhtawar
Published: October 2015

A study was undertaken to develop an appropriate plan of land use under suitable slope gradient to control soil erosion from a red soil hilly watershed of southern China by using the GeoWEPP (Geo-spatial Interface for the Water Erosion Prediction Project) model. The model was calibrated and validated using monitoring data of the outlet from 2010 to 2012, in which the 2010 and 2012 annual total runoff and sediment yield data were used for calibration, and the 2011 monthly runoff and sediment yield data for validation. The performance of the model in validation period were good with a high coefficient of determination values of 0.98 and 0.93 and Nash-Sutcliffe simulations of 0.96 and 0.91 while low root mean square error values of 6.91 mm and 0.35 t respectively for runoff and sediment yield. Subsequently, the model was used to simulate four typical land use (forest, farm, orchard, and fallow land) in the study area to evaluate their impacts on soil erosion production. The results showed that the runoff decreased by 44.7% and 61.1% for forest and orchard land compared to the current land use, as well as the sediment yield decreased by 43.7% and 68.6%. While the runoff and sediment yield increased by 52.2% and 42.6% for farm land, and 48.8% and 29.6% for fallow land. As the same time, soil erosion increased with increasing of the slope gradient of the quadratic regression equation for all land use. The critical slope gradient of 15° for returning the farmland to forest or others is suitable in the red soil region but is not accurate. The result of the study provides good scientific evidence for developing an appropriate plan of land use in the watershed and other similar areas.
Requirements within the Ebola Viral Glycoprotein for Tetherin Antagonism
Authors: Vande Burgt Nathan , Kaletsky Rachel , Bates Paul
Published: October 2015

Tetherin is an interferon-induced, intrinsic cellular response factor that blocks release of numerous viruses, including Ebola virus, from infected cells. As with many viruses targeted by host factors, Ebola virus employs a tetherin antagonist, the viral glycoprotein (EboGP), to counteract restriction and promote virus release. Unlike other tetherin antagonists such as HIV-1 Vpu or KSHV K5, the features within EboGP needed to overcome tetherin are not well characterized. Here, we describe sequences within the EboGP ectodomain and membrane spanning domain (msd) as necessary to relieve tetherin restriction of viral particle budding. Fusing the EboGP msd to a normally secreted form of the glycoprotein effectively promotes Ebola virus particle release. Cellular protein or lipid anchors could not substitute for the EboGP msd. The requirement for the EboGP msd was not specific for filovirus budding, as similar results were seen with HIV particles. Furthermore trafficking of chimeric proteins to budding sites did not correlate with an ability to counter tetherin. Additionally, we find that a glycoprotein construct, which mimics the cathepsin-activated species by proteolytic removal of the EboGP glycan cap and mucin domains, is unable to counteract tetherin. Combining these results suggests an important role for the EboGP glycan cap and msd in tetherin antagonism.
CHALLENGES IN THE IMPLEMENTATION OF PUBLIC ELECTRONIC SERVICES: LESSONS FROM A REGIONAL-BASED STUDY
Authors: Ferreira Neuza C. M. Q. F. , Ferreira Fernando A. F. , Marques Carla S. E. , Ilander Guillermo O. Pérez-Bustamante , Çipi Amali
Published: October 2015

Building the information and knowledge society has involved the development of numerous projects and initiatives all over the world. Portugal is no exception. This work is based on the analysis of the ALO Digital Project, which involves a series of strategies developed at the local e-government level in four Portuguese counties near Lisbon (i.e. Amadora, Loures, Odivelas and Vila Franca de Xira). Having the residents of the four counties involved as the target, this paper aims to identify the level of electronic service use resulting from the implementation of the ALO Digital Project. A questionnaire was administered and the results of a regression analysis demonstrate that the project is still at low level of online service sophistication. Additionally, despite users’ overall satisfaction, implementation difficulties were noticed. In practical terms, this reveals a type of service more related to information consultation, downloading and printing documentation, and supports the premise that a change of focus and direction of local e-government is needed to substantially improve the life of the individual citizen.
Achieving a National Sample of Nursing Homes: Balancing Probability Techniques and Practicalities
Authors: Fielding Elaine , Beattie Elizabeth , O'Reilly Maria , McMaster Mitchell ,   The AusQoL Group
Published: October 2015

Sampling design is critical to the quality of quantitative research, yet it does not always receive appropriate attention in nursing research. The current article details how balancing probability techniques with practical considerations produced a representative sample of Australian nursing homes (NHs). Budgetary, logistical, and statistical constraints were managed by excluding some NHs (e.g., those too difficult to access) from the sampling frame; a stratified, random sampling methodology yielded a final sample of 53 NHs from a population of 2,774. In testing the adequacy of representation of the study population, chi-square tests for goodness of fit generated nonsignificant results for distribution by distance from major city and type of organization. A significant result for state/territory was expected and easily corrected for by the application of weights. The current article provides recommendations for conducting high-quality, probability-based samples and stresses the importance of testing the representativeness of achieved samples.

[Res Gerontol Nurs. 2016; 9(2):58–65.]
Mechanical Properties and Wear Resistance of PM Composite Materials Reinforced with the Halloysite Particles
Authors: Dobrzański Leszek Adam , Tomiczek Błażej , Pakieła Wojciech , Tomiczek Anna Ewa
Published: October 2015

The purpose of this work is the development of the aluminium alloy matrix composite materials using powder metallurgy technologies, including mechanical alloying and hot extrusion with the required properties and structure of the designed material. In this work halloysite nanotubes, was used as alternative reinforcement of metal matrix composites. Halloysite is a clayey mineral of volcanic origin, characterised by high porosity, high ion exchange, large specific surface and easy chemical, as well as mechanical treatment. High energy ball milling leads to uniform distribution of the halloysite reinforcing particles throughout the AlMg1SiCu matrix and simultaneously reduces the particle size. Proved microstructural changes influence the mechanical properties, especially microhardness, and compression yield, as well as wear resistant. The tribological analysis reveals that composite materials – irrespective of the measuring cycles number and load – are characterised by much smaller wear volume in comparison to the matrix material. The MMCs obtained as a result of mechanical alloying, cold compacting and hot extrusion are characterised with the microstructure of homogeneous distribution of halloysite particles in fine-grain matrix of AlMg1SiCu alloy, facilitate the obtainment of higher values of mechanical properties, compared to the base alloy. The composite materials reinforced with nanoparticles with 15% mass share are characterised by more than 180% higher yield strength and almost twice as higher microhardness compared to the matrix material. The analysis of the investigation results has confirmed that halloysite nanotubes can be applied as effective reinforcement in the MMCs.
Influence of Thermo-Mechanical Treatments on Structure and Mechanical Properties of High-Mn Steel
Authors: Dobrzański Leszek Adam , Borek Wojciech , Mazurkiewicz Janusz
Published: October 2015

The aim of this paper is to determine the high-manganese austenite propensity to twinning induced by the cold working and its effect on structure and mechanical properties, and especially the strain energy per unit volume of new-developed high-manganese Fe – Mn – (Al, Si) investigated steel, containing about 24,5 % of manganese, 1% of silicon, 3 % of aluminium and microadditions Nb and Ti with various structures after their heat- and thermo-mechanical treatments. The new-developed high-manganese Fe – Mn – (Al, Si) steel provide an extensive potential for automotive industries through exhibiting the twinning induced plasticity (TWIP) mechanisms. TWIP steel not only show excellent strength, but also have excellent formability due to twinning, thereby leading to excellent combination of strength, ductility, and formability over conventional dual phase steels or transformation induced plasticity (TRIP) steels. Results obtained for high-manganese austenitic steel with the properly formed structure and properties in the thermo-mechanical processes indicate the possibility and purposefulness of their employment for constructional elements of vehicles, especially of the passenger cars to take advantage of the significant growth of their strain energy per unit volume which guarantee reserve of plasticity in the zones of controlled energy absorption during possible collision resulting from activation of twinning induced by the cold working as the fracture counteraction factor, which may result in significant growth of the passive safety of these vehicles' passengers.
Application with Simultaneous Electrocontact Heating Stretching to Reduce Residual Stresses in the Heat Exchange Tube
Authors: Shimov Georgy , Serebryakov Andrey , Serebryakov Aleksander
Published: October 2015

The main reason of appearance and growth of corrosion damages of the nuclear steam generator heat exchanger tubes is the process of stress-corrosion cracking of metal under the influence of residual tensile stress.The article contain the suggestion of the method that combines the operation of heat processing and straightening of pipes by stretching. The approbation of the method was carried out in the laboratory conditions. There is described the construction and working principle of a trial installation. During the experiments different parameters of electrocontact heating with stretching were tested. Approbation showed that the proposed method can reduce the level of tensile residual stresses or get compressive residual stresses in the wall of the tubes, which increases their resistance to corrosion.Keywords:Steam generator, heat exchange tubes, stress corrosion cracking, intercrystalline corrosion, residual stresses
Effect of Accelerated Spheroidisation and Long Annealing of 100CrMnSi6-4 Steel on Structure and Properties after Hardening
Authors: Hauserova Daniela , Dlouhý Jaromír , Novy Zbysek
Published: October 2015

Accelerated carbide spheroidisation enables significant shortening of time necessary for formation of steel microstructure consisting of ferritic matrix and globular carbides. Conventional way to obtain such structure is long duration soft annealing after semiproduct hot forming. Research of accelerated carbide spheroidisation showed that it is possible to spheroidise lamellar pearlite in minutes. Accelerated carbide spheroidisation produces very similar microstructure like conventional soft annealing in morphological point of view, but carbide particles and grain size of the matrix is significantly smaller. Finer microstructure results in higher hardness in comparison with conventionally annealed steel. Finer microstructure also ensures more homogeneous and finer structure after final heat treatment, after hardening. This fact indicates, that properties of final product differ according to previous structure after soft annealing. Finer carbides in structure enhance hardness and facilitates carbide dissolution during austenitisation. This effect enables quenching temperature lowering. Steel 100CrMnSi6-4 microstructure and properties are compared in view of various kind of spheroidisation and quenching temperature.
Forming a Structured Surface of a New Type of Solar Absorber with Hydroforming
Authors: Mrňa Libor , Řiháček Jan
Published: October 2015

One of the ways to increase efficiency of the solar absorber is modification of absorption area in the system of pyramidal cavities, where the incident radiation is absorbed by multiple reflections. The paper deals with the technology of production of the flow solar absorber with a structured surface in a single technological operation using hydroforming. Two laser-welded sheets are inserted into the forming chamber. Then the space between them is pressurized with hydraulic fluid which causes their form to the desired shape. The first part of this article describes hydroforming device. The second section deals with theoretical simulation of forming a different structured surface in the programming environment of ANSYS. As follows practical test of hydroforming is performed. Austenitic stainless steel X5CrNi18-10 was used as a material for the production of samples.
In Situ Testing and Heterogeneity of UFG Cu at Elevated Temperatures
Authors: Petrenec Martin , Král Petr , Dvořák Jiří , Svoboda Milan , Sklenička Václav
Published: October 2015

Experiments were conducted to investigate deformation-induced processes during in-situ tensile test at elevated temperature. Consequently the microstructure after creep loading was examined by 3D Electron Back Scatter Diffraction (EBSD) technique. The billets of coarse-grained copper were processed by equal-channel angular pressing (ECAP) at room temperature using a die that had an internal angle of 90° between the two parts of the channel and an outer arc of curvature of ~ 20°, where these two parts intersect. The pressing speed was 10 mm/min. To obtain an ultrafine-grained (UFG) material, the billets were subsequently pressed by route Bc by 8 ECAP passes to give the mean grain size ~ 0.7 μm. The constant strain-rate test in tension was performed at 473 K using testing GATAN stage Microtest 2000EW with EH 2000 heated grips which is configured for in-situ electron back scatter diffraction (EBSD) observations. Microstructure was examined by FEG-SEM TESCAN MIRA 3 XM equipped by EBSD detector HKL NordlysMax from OXFORD INSTRUMENT. The tensile test was interrupted by fast stress reductions after different deformation step and observation of microstructure changes was performed. Despite of a considerable interest in ECAP processing method, there are not many works documenting microstructure evolution and changes during creep testing and determining creep mechanisms of ultrafine-grained materials processed by ECAP. It was found that creep resistance of UFG pure Al and Cu is considerably improved after one ECAP pass in comparison with coarse grained material, however, further repetitive pressing leads to a noticeable deterioration in creep properties of ECAP material. Recently it was observed the coarsening of the grains in microstructure of ECAP copper during creep at elevated temperature. It was suggested that creep behaviour is controlled by storage and dynamic recovery of dislocations at high-angle boundaries. In the present work was found that ultrafine-grained microstructure is instable and significant grain growth has already occurred during heating to the testing temperature. Static recrystallization during heating led to the formation of high fraction of special boundaries Σ3 and Σ9. The tensile deformation at 473 K led to the additional grain growth and formation of new grains. Microstructure was investigated also by 3D EBSD.
Optimization of Microstructure of the Low Alloy Structural Steel Using Rare Earth Metal (REM) Addition
Authors: Jonšta Petr , Machovčák Pavel , Sušovský Michal , Trefil Antonín , Brožová Silvie , Vu The Ha , Drápala Jaromír , Rykalová Eva
Published: October 2015

A general trend in steelmaking industry is to increase strength, resistance to brittle fracture and fatigue properties of steel products at favorable price. Achieving fine-grained microstructure during austenite to ferrite transformation is a basic prerequisite to improve the mechanical properties. The desired transformation can be achieved in several ways one of which is the use of small non-metallic inclusions as heterogenous nucleation sites during solidification of steel. A great attention is focused on this concept in recent years. Rare earth metals are suitable for the formation of small inclusions similarly as in the case of conventional microalloying elements such as niobium, titanium, vanadium and other. Rare earth metals have a high affinity to oxygen and sulfur. The paper deals with the optimization of microstructure of 42CrMo4 low alloy structural steel used for machine parts exposed to higher stresses. The steel was alloyed with cerium in the form of mischmetal to achive fine-grained microstructure. Operational experiment was proposed and realized in accordance with results of laboratory experiment.
Combination of International High Pressure Forming and Q-P Process for Production of Hollow Products from Ahs Steel
Authors: Mašek Bohuslav , Vorel Ivan , Jirková Hana , Kurka Petr
Published: October 2015

All sectors of industry experience high demand for shaped products with as good mechanical properties as possible at low costs. Automotive industry, in addition, requires that the parts are of lightweight construction. Consequently, new types of materials and processes have to be combined to design new production chains capable to meet this demand. For instance, there are high-strength low-alloyed steels, whose final properties are attained by advanced heat treating techniques. One of such techniques is the Q&P process which can deliver excellent ultimate strengths exceeding 2000 MPa at a sufficient elongation level of 10 %. When combined with an unconventional forming method, it allows complex-shaped parts with outstanding mechanical properties to be made. One example of such combined procedure is the sequence of internal high pressure forming, hot stamping and Q&P processing. In the present study, thin-walled hollow stock was processed using such a combined procedure. After stepwise optimization of processing parameters, products with martensitic structure and a small amount of bainite were obtained. In all locations of the product which were tested, the ultimate strength exceeded 1950 MPa and elongation reached 15 %
New Type of Device for Achievement of Grain Refinement in Metal Strip
Authors: Rusz Stanislav , Čížek Lubomír , Michenka Vít , Dutkiewicz Jan , Salajka Michal , Hilšer Ondřej , Tylšar Stanislav , Kedroň Jan , Klos Marcel
Published: October 2015

DRECE - Dual Rolls Equal Channel Extrusion" (dual rolls pressure combined with equal channel extrusion) method is used for production of metallic materials with very fine grain size (hereinafter referred to as UFG structure - Ultrafine Grain Size). During the actual forming process the principle of severe plastic deformation is used. The device is composed of the following main parts: “Nord” type gearbox, electric motor with frequency speed converter, multi-plate clutch, feed roller and pressure rollers with regulation of thrust, and of the forming tool itself – made of Dievar steel type. Metallic strip with dimensions 58×2×1000 mm (width x thickness x length) is inserted into the device. During the forming process the main cylinder in synergy with the pressure roller extrude the material through the forming tool without any change of cross section of the strip. In this way a significant refinement of grain is achieved by severe plastic deformation. This method is used for various types of metallic materials, non-ferrous metals and their alloys. Forming process is based on extrusion technology with zero reduction of thickness of the sheet metal with the ultimate aim - achieving a high degree of deformation in the formed material. The DRECE device is also being verified from the viewpoint of achievement of a UFG structure in a blank of circular cross-section (wire) with diameter of ø 8 mm × 1000 mm (length).
Enhancing Bitumen Flotation with Colloidal Nanoparticles
Authors: Kuznetsov Oleksandr V. , Suresh Radhika , Agrawal Devesh K. , Mazyar Oleg A. , Feng Xianhua , Behles Jacqueline A. , Khabashesku Valery N.
Published: October 2015

In bitumen flotation, ultra-dispersed hydrophilic nanoparticles are found to be capable of stabilizing biwettable ore fines in aqueous phase by adsorbing onto fines surfaces. As a result, fine solids move away from oil/water interfaces reducing slime-coating onto liberated bitumen droplets. It was demonstrated that reduction of slime-coating increases bitumen recovery during flotation of low grade ore by more than 5%. Addition of nanoparticles has no negative effect on froth quality as well as on oil, water and solids separation in naphthenic and paraffinic froth treatment processes. Detailed molecular dynamics (MD) simulations revealed mechanisms which improve bitumen liberation from mined oil sands in flotation process. Therefore our studies demonstrate that colloidal nanoparticles affect all stages of bitumen extraction process from bitumen separation to clay wettability alteration.
Phase Behavior of CO2-Rich Live Oil Samples From High Pressure Reservoirs
Authors: Cardoso F. M. R. , Viegas C. C. B. , Fleming F. P. , Freitas R. S. , Vieira A. J. M. , Rosa P. T. V. , Carrier H. , Daridon J-L
Published: October 2015

Oil production activities are strongly dependent on the phase behavior of produced fluids. Among the usual phase changes, those that lead to the appearance of one or more solid phases are among the main focus of flow assurance studies. The flocculation of asphaltenes, the heaviest and most polar fraction of crude oil, usually occurs downhole at high pressure and temperature conditions. To assess the live oil phase behavior, four samples were evaluated using a high pressure microscope (HPM). The results obtained from HPM isothermal depressurization experiments revealed the existence of four different phase behavior patterns, suggesting the existence of a liquid-liquid equilibrium at elevated temperatures and pressures in CO2-rich fluids. The pictures and videos acquired from the HPM showed that the the second liquid phase droplets hardly coalesce, suggesting either a low interfacial tension between the two coexisting liquids or the presence of a natural surfactant at the interface. This unusual phase behaviour is not promptly antecipated by thermodynamic simulations, rendering unavoidable the experimental characterization of live oil samples. In light of this new scenario, techniques that only evaluate the appearance of a different phase like the solid detection system (SDS) analysis based on the light scattering in the NIR region are not conclusive when used independently. HPM analysis or the combination of different techniques like SDS and isobaric filtration, become indispensable in order to assess solids formation in live oil samples above their bubble points.
Identification While Drilling of Drill-String Dynamic Model for Diagnostics and Optimization
Authors: Veltman A. , Stulemeijer I. , Catena A.
Published: October 2015

The main objective of this paper is to improve drilling performance by obtaining a representative dynamic model of a drilling system: top-drive, controls, drill-pipe and bottom hole assembly (BHA). High-fidelity simulations with a representative analytical model are a goal necessary to optimize controller-settings while or before drilling. Goals such as ‘lowest sensitivity to torque disturbance at the bit’ or ‘best reaction to stick-slip events’ can be pursued while guarding stability limits of the full system.

The method is based on spectral correlation between at least two signals: a broad-band signal with frequencies in the relevant band (0.05Hz to 5Hz) added to the top-drive's torque command and second: the measured top-drive speed. Mathematical tools from seismic exploration and control-theory are used to determine key parameters of this closed-loop system. Correlation techniques allow identification even during high background noise generated by varying friction and bit-cutting forces in most cases.

Experimental results from a number of wells in Oman, Malaysia, and USA show that the transmission-line based model can be accurately matched at all depths. Besides the eigen frequency, a number of higher modes of the drill sting are found, including their effective damping. The identified response agrees with expected response based on pre-computed mechanical drill-string composition parameters. In one well a substantial increase in friction and bit-inertia was identified at certain depth intervals. Logs taken afterwards showed wash-outs at these depths, suggesting diagnostic potential of this estimation technique.

Novel is the ability to identify a dynamic drill string model without advance information, yielding auto-tuning capability for most stick-slip mitigation technologies such as ‘softtorque’. A very welcome benefit is the estimation of the string's characteristic impedance and length but also internal and external friction components along the string and at the bit. Traditionally, these damping terms are often neglected, exaggerated or set to an agreeable value to limit the amplitude of resonances in the calculated model. The presented identification method generates updates of these different damping terms every ten minutes or so. During drilling several wells, the found damping terms are spread over a wide range due to mud-pipe, pipe-wall interaction and bit-formation variability. We conclude that damping terms cannot be ignored without severely compromising the dynamic fidelity of the model. Future diagnostic and drilling optimization tools may be based on this new way of harvesting information from down hole.
Inlet Effects on Flow Regimes in Downwards Inclined Pipes
Authors: Diaz M. , Nydal O. J.
Published: October 2015

Multiphase flow models require models for each flow regime, and models for the transition between the regimes. Dynamic slug flow models also aim at predicting the slug formation and decay as well as the statistical distributions of lengths, frequencies and velocities.

Previous experimental studies have demonstrated the existence of a region in the flow regime map where both stratified and slug flow can be stable flow regimes, typically for low pressure systems. This phenomenon can also lead to large flow transients at the point of stratified-slug transition, with excess liquid transported out of the pipeline in the form of a large liquid slug, with length depending on the pipe geometry and length.

This phenomenon is experimentally investigated for 3 degrees downwards air-water flow in a 16 m long pipe of 60 mm internal diameter. An inlet section of 3 m long was configured at 14.6 degree downward and 25 degrees upward, in order to generate either stratified flow or slug flow. The statistical analysis of the slug frequency and length distribution was examined, and the results show a premature stratified-slug transition when slug flow is set as inlet condition. The slug formation and evolution along the pipeline was studied by tracking the slugs at different locations in the downward pipe. Results were compared against flow patterns predicted by a commercial simulator.
Simplified Hydraulic Design Methodology for a Subsea Inline Oil-Water Pipe Separator
Authors: Stanko M. , Golan M.
Published: October 2015

This paper introduces and demonstrates a simplified hydraulic design methodology of an oil water pipe inline separator for subsea deployment in a hydrocarbon production system. The oilwater pipe separator consists of an inclined tube section with evenly spaced tapping points at the bottom from where water rich streams are withdrawn.

Two main steps of the hydraulic design process are discussed in detail and demonstrated using numerical modeling, synthetic and literature data. The steps are: 1) assessing the potential production gain of installing the inline separator in a subsea production system and identifying the required separator performance and 2) Quantifying the separation performance of a single tapping and predicting the separation performance of a group of tapping points.

The results show that the proposed methodology can be successfully used to: Evaluate the potential gain in oil production when installing a subsea oilwater separator; Obtain a rough approximation of the required performance of the separator (required drained water flow rate and associated oil content) to achieve a given desired production increase; and estimate the approximate number of tapping points required and their operating conditions.

The concepts and methodology discussed in the present work can be easily generalized to other subsea separation techniques. They allow to determine the feasibility of installing a separator on a subsea production system and a concept to measure and predict the performance of separation techniques based on tapping.
Regulatory Approaches for Safety of Personnel Transfer Baskets
Authors: Paula Henrique
Published: October 2015

There are different approaches for regulating the offshore transfer of personnel using personnel transfer devices (e.g., transfer baskets). This article summarizes the regulatory approaches used by several countries and offers remarks about the spectrum of regimes that can be used. Additionally, this article illustrates an interenationally recognized Type Approval program, as it applies to these transfer devices. The Type Approval program supports and complements the efforts of the industry (manufacturers, operators etc.) and regulatory bodies in helping ensure the safety of personnel during transfers.