bluuebunny/crossref_metadata_2025 huggingface dataset:
Coiled Tubing Deployed Multistage Horizontal Fracturing Technology: Lesson Learned and Case History in Egypt
Authors: Kareem E. Abdel , Salah M. , Farran A. El , Conrad B. , Beltagy A. El
Published: March 2015

Economic production from marginal reserves in mature fields has always been a major development challenge. Drilling horizontal wells and deploying coiled tubing (CT) multistage hydraulic fracturing stimulation treatments is now a proven solution for mature field development because it exposes more stimulated production zones.

Khalda and Umbarka fields are two mature fields located in the Egyptian Western Desert. They are characterized by their low, depleted reservoir pressure and laminated shaley sands (Upper Bahariya formation). Their hydrocarbon reserve contents are significant. However, because of their relatively low permeability and thin layers, it is very difficult to produce economically from this formation without using hydraulic fracturing. Single-stage hydraulic fracturing treatments in vertically drilled wells resulted in a production of 25 to 40 B/D per well, which is uneconomic for field developments.

Drilling horizontal wells into the best sand layer of the Upper Bahariya sand and performing seven isolated stages of hydraulic fracturing treatments by deploying CT technologies resulted in impressive production responses (1,800 B/D initial production) from this reservoir, which makes this development economical. Deploying CT to the operations exponentially improved its efficiency; seven isolated fracturing stages were performed along the lateral and more than one million lbm of proppant was pumped during three days through one single CT trip in the well.

This paper provides a comprehensive description of the lessons learned from two case histories where CT fracturing techniques for multistage stimulation were applied to achieve maximum production in the field and improve the efficiency of multistage fracturing operations.
Coiled Tubing Deployed Gas and Water Shutoffs in Alaska Utilizing a Polymer Gel and Microfine Cement
Authors: Robertson D. B. , Brown M. A. , Duong L.H. , Ivanova O.V. , Tambe A.
Published: March 2015

A common problem in oil and gas wells is excess free gas or water production from only certain portions of the completed interval. Other portions of the lower completion may still have viable oil or gas production potential if a method can be devised to successfully shut off the unwanted fluids. A coiled tubing deployed profile modification technique was developed primarily to shut off excess free gas production from the heel of cased and perforated horizontal oil wells. The technique has also been used for water and gas shut-off in both vertical and horizontal wells in a variety of lower completion types. The technique involves installing a temporary plug back to protect the toe or bottom most perforations to be preserved, then pumping a polymer gel followed immediately by a microfine cement to shut off the shallower or heel perforations. The objective of the gel and cement is to intentionally damage the rock matrix for a radius of ~2 ft around the perforated intervals to be shut off, creating a zone of little or no permeability adjacent to the wellbore. If successfully executed, there is no cement to be milled out of the liner post squeeze and no restrictions or liner diameter reduction after the job. Approximately 30 horizontal wells have had a cumulative total of almost 13,000 ft of perforated intervals squeezed with this method. The technique has also been used to shut off liner corrosion leaks in horizontal wells and for perforation shut off in deviated wells. Post-job production logs in several of the wells indicated little or no flow from the squeezed intervals even 1 to 2 years after the job.
Milling Faulty Lubricator Valve Using Innovative E-Line Conveyed Core Bit
Authors: Seng Wong Chun , Maitland Bryan , Singh Jagdish , Elnaeim Mohamed Ibrahim
Published: March 2015

Field A is a gas field located in Malaysia-Thailand Joint Development Area. As the field matures after 10 years of production, the number of idle gas wells has been increasing due to various issues such as low tubing head pressure, mechanical problems and sand fill. Currently, the operator has embarked on an aggressive, reactivation campaign to restore production through interventions.

Well A became idle in January 2013 due to unknown reasons and was selected as a pilot well for the re-activation campaign. Tubing Retrievable – Surface Controlled Subsurface Safety Valve (TR-SCSSV) cycling and Critical Device Function Test (CDFT) were performed successfully, but did not impact the production. In August 2013, lubricator valve (LV) diagnostics were performed using a Lead Impression Block (LIB) tool which indicated that the lubricator valve above the TR-SCSSV was only 80% open. As such, this malfunctioning lubricator valve (LV) prevented any future interventions for diagnostics, zonal isolation or the addition of perforations in order to fulfill the objectives of the idle-well reactivation campaign.

An in-depth, internal review had been conducted previously to evaluate all the available solutions in the market from both a technical and economic perspective. To enhance the chances of success, an innovative e-line conveyed core milling bit solution was selected for the pilot job in well A to restore full access to the well.

A customized solution using a 4.55 inch milling core bit run on e-line managed to successfully mill the malfunctioning lubricator valve and restore access to the well with substantial cost savings and lower risk compared to coiled tubing (CT) operation. Both milled coupons were retrieved with the aid of a catcher and brush combination designed into the bit. This managed to restore the access for the future intervention, zonal isolation and additional perforations in this well.

This paper shares a detailed case study of Well A in terms of technology selection, operation execution, lessons learnt, and future recommendations. It is evident that e-line conveyed, core milling bit technology is technically and economically feasible to mill malfunctioned lubricator valve, thus eliminating the need of expensive solutions such as CT or rig intervention.
Recent Developments in Mechanical Descaling Operations: A Case Study from Saudi Arabia
Authors: Al-Buali M.H. , Abulhamayel Nahr , Leal Jairo , Ayub Mohammed , Driweesh Saad , Molero Nestor , Ahmed Danish , Raza Ali , Valley Joseph La , Alfonzo R.I. Ortega , Vejarano E.R.
Published: March 2015

Scale removal in sour gas wells has been one of most challenging operations in Saudi Arabia during the last decade. Operators face particularly demanding downhole environments with temperatures above 300 °F, significant concentrations of H2S and CO2, presence of complex mixed-scale deposits with limited dissolution, and risk of H2S release and corrosion with chemical removal methods. These conditions have led to mechanical removal methods using coiled tubing (CT) as the preferred technique for well descaling operations.

During the last 5 yr, CT descaling operations have consisted of temporary formation isolation via bullhead using CaCO3 chips as a bridging agent, mechanical scale removal with CT milling and high-pressure rotary jetting tools, and abrasive perforation or matrix stimulation to enhance well productivity. Mechanical alternatives for isolation with bridge plugs are not feasible due to the presence of FeS scale in the wellbore. Wellbore configurations also require pump rates above 2.0 bbl/min to ensure suitable cleanout and transportation of solids to surface.

The recent incorporation of CT equipped with a rugged version of fiber optic telemetry and a downhole measurements package into the descaling operations workflow has enabled pumping rates above 2.0 bbl/min. Key bottomhole data has also been obtained, leading to a better understanding of the scale removal progress, optimization of downhole tool operation; reduced well intervention risk, and enhancement of overall job efficiency.

During the CT mechanical descaling stage, differential pressure across a high-pressure rotary jetting tool was kept at its optimum range of operation while maintaining slight overbalance conditions to minimize the risk of gas influx and avoid loss of circulation while removing the formation isolation. Throughout the abrasive perforating stage, real-time depth correlation saved one CT run (i.e., ±24 hr), and higher pump rates significantly reduced operation time and maximized shot size and penetration.

This paper discusses an enhanced workflow for CT descaling operations where the implementation of the real-time downhole measurements package with an enhanced working envelope resulted in a significant increase in operational efficiency, reduced risk, and optimized job performance.
A Novel Fatigue Assessment of CT with Defects Based on Magnetic Flux Leakage
Authors: Liu Zhanke , Zheng Andrew , Diaz Oscar O. , Hauglund Lauren
Published: March 2015

Conventional models have been proven to be successful in predicting the mechanical fatigue life of coiled tubing (CT) without defects. However, defects of various types, including mechanical, manufacturing or corrosion defects, on CT are commonplace in the real world. The impact of such defects on CT fatigue life has been widely recognized. Today's common practice heavily relies on prove-up and manual measurement of defect dimensions, to assess the defect severity on tubing integrity issues, such as fatigue life. Such practice tends to be inefficient, user-dependent, and inconsistent in fatigue and severity assessment; sometimes it's even not feasible in the case of internal defects.

A novel defect severity analysis based on magnetic flux leakage (MFL) was used to quantitatively assess the CT fatigue life reduction due to mechanical defects. This new quantitative approach allows consistent, automated in-line fatigue analysis during operation, as it does not depend on a user's manual measurement of defect dimensions. The new model results compared well with experimental data. The analysis method was successfully used in fatigue assessment of realistic field defects.
Achieving Economically Successful Coiled Tubing Composite Plug Drillouts in Extended Reach Wells
Authors: Ahn J.
Published: March 2015

As horizontal completions are set at increasing depths, an efficient and economical composite plug coiled tubing (CT) drillout (CTDO) process becomes increasingly important. Therefore, it becomes a significant challenge when multiple composite plugs must be drilled out within a single well. By evaluating and making enhancements to each part of the process, thus reducing and possibly eliminating wiper trips, CT can provide an economic solution for these extended reach composite plug drillouts. The net benefits of this include less pipe fatigue, less fluid and chemicals pumped, and an overall more efficient and economic drillout. Extended reach plug drilling operations require particular attention to detail, combining technical, equipment, and operational improvements to reliably reach total depth (TD) in an efficient and safe manner.

This paper discusses the importance of the following six areas suggested for a successful plug drillout process: CT string design related to wellbore tubulars and deviation.Bottomhole assembly (BHA).Flowback arrangement.Drilling techniques.Fluid system.Monitoring and control during the job of the associated drillout parameters.

This paper additionally focuses on two case histories where wiper trips were successfully minimized/eliminated using the discussed method and process enhancements. The first of these is in the Williston basin, where a well (10,135 ft vertical and 9,868 ft lateral) with 24 composite plugs was successfully drilled out using 22,230 ft of 2 3/8-in. CT. In the Denver-Julesburg (DJ) basin, a well (6,780 ft vertical and 7,815 ft lateral) with 39 composite plugs was successfully drilled out using 17,990 ft of 2-in. CT.

The synergy of the six areas followed during the CTDO operations has proven to be a cost effective and reliable process, saving the operator well intervention time. Results and recommendations are presented including the lessons learned from the implementation of the process enhancements within these two case histories.
Optimizing CT Milling Efficiency with the Use of Real-Time CT Modeling Software
Authors: Yeung John , Opel Steve , Smalley Ed
Published: March 2015

In the last decade, the number of horizontal wells drilled in North America has risen dramatically. As a result, there has been an associated increase in the use of the plug and perforation system and the ball-drop system used to complete these horizontal wells. After the fracturing treatment has been completed, the bridge plugs or ball seats are subsequently milled out via the use of coiled tubing (CT).

During the plug or ball-seat milling phase, it is difficult to control weight-on-bit at the end of the CT. If the injector releases too much weight at surface, then the weight-on-bit is too high and the downhole motor can experience a stall. Alternatively, if the injector is not releasing enough weight at surface, then there is insufficient weight-on-bit to mill out the plug or ball-seat. Given that these operations are performed in horizontal wells, it is difficult to predict the optimal weight-on-bit without the presence of real-time downhole measurements.

The current data acquisition software used on CT field operations does not analyze or interpret the data - - it only records the measurements. As a result, it is an arduous process to identify trends in pressure, depth or CT string weight changes over an extended period of time. However, analyzing changes in these variables is critical for optimizing the CT milling operation.

This paper focuses on an innovative technique for analyzing real-time CT job data that can be used to calculate the required surface weight needed to achieve the optimal weight-on-bit. Furthermore, the technique also enables real -time interpretation of CT job data to confirm that the mill is making the desired progress. This technique has been implemented as a utility within a leading CT modeling software package. This paper will also present field case studies that demonstrate how the new CT interpretation utility software has optimized the milling efficiency in horizontal wells.
Cost Effective Solutions to Achieve Injection Post Toe Valve Failure
Authors: Trebing Cody , Whitworth Jeff , Beszterda Alex
Published: March 2015

The use of pressure-activated toe valves in a completion string is yet another innovative approach to completing a horizontal well. This technology eliminates the need for perforating guns prior to a multi-stage hydraulic fracturing (frac) operation. Subsequently, the operator can greatly reduce costs when the need for coiled tubing (CT), wireline (WL), or workover rig (WOR) is no longer needed on location to convey perforating guns.

However, when injection rate through the toe valve is not adequate for wireline pump-down operations, or the toe valve fails to open at all, the operator must revert back to conventional methods of perforating in order to achieve injection into the well and begin the frac operation. These failures immediately negate any of the cost savings the toe valves were designed to provide. This paper will review cost effective solutions, through the use of abrasive perforating, to quickly and efficiently perforate the toe stage and minimize non-productive time (NPT).

Most often, adequate pump-down rate is not achieved through the toe valve when debris or cement is lying across the tool, preventing it from opening or plugging off the ports. Prior to perforating, a motor and bit run is common to verify that the well is clean down to plug back total depth (PBTD). This requires a minimum of two round trips with coiled tubing or a workover rig. Two different methods of abrasive perforating have been used to benefit both conventional plug and perforate and frac sleeve completions (sometimes referred to as “baffles”). Several case histories will be presented to explain how a single trip in hole, utilizing a motor BHA and abrasive perforator in tandem to clean and perforate the toe stage, can minimize costs compared to several round trips using the conventional method with perforating guns. Additionally, we will explore an innovative approach to abrasively perforate the toe stage through frac sleeves where minimal ID's pose a problem with conventional methods of perforating.

Abrasive perforating technology, in conjunction with other innovative tools, adds a wide range of flexibility for today's complex horizontal wells. Utilizing this technology, problems such as toe valve failures can be addressed in a safe and cost effective manner.
Two Decades of Wireline Tractor Experience – One Operator Perspective From the Norwegian Continental Shelf
Authors: Buchanan Alastair , Koldal Hans Morten , Sælensminde Thor
Published: March 2015

Electric wireline tractor conveyance technology was introduced to Statoil operations in Norway in the mid 1990′s. Uptake was rapid and the technology offerings expanded to include ‘powered mechanical’ services run in conjunction with wireline tractor conveyance – further development and expansion of these services is on-going. This development is to a large extent reflected in global oilfield operations with widespread acceptance and application of these technologies.

Since 2008 a detailed record has been maintained of wireline tractor operations and runs for Statoil operations. This database is used to rapidly identify reference operations for on-going activities but also serves as a source of statistical information useful for strategic planning. The database is currently populated with information on over 900 separate wireline tractor operations and over 3000 individual runs – the vast majority of the data is from operations in Norway with some additional activity in Brazil and on US land operations.

There is a large, and growing, collection of technical papers addressing the technology and operations related to wireline tractor and related services. Most of these publications refer to specific technology descriptions and individual, or collected, case histories. With the aforementioned database of information we believe that there is a good basis for providing a more ‘holistic’ review of the results of applyling tractor and related technology – at least within the context of Statoil drilling and well operations in Norway.

This paper will: Discuss the introduction and uptake of tractor related services within the historical context of Statoil operations in Norway.Provide context in terms of the reservoir, well and operational environments encountered on Statoil operations in Norway.Provide a statistical overview of the applications of wireline tractors and related technologies for Statoil in Norway.Discuss the success rate of various applications of the technology within the context of Statoil operations in Norway.Discuss future challenges and opportunities.
Light Well Intervention Using Conventional Slickline and Electric Line off the East Coast of Canada
Authors: Loov R. , Locken D. , McInnes N. , Chippett E.
Published: March 2015

Well intervention is a critical aspect of managing brownfield assets as operators seek to optimize hydrocarbon recovery and perform maintenance work to ensure wellbore integrity. The costs of traditional workover methods and technologies, specifically in an offshore environment, can create economic barriers to the number and types of interventions that are completed in a declining field. Light well intervention technology is considered a cost effective alternative to performing rig interventions on aging subsea wells.

Operators and service providers continually seek to develop technologies and procedures that mitigate economic risk when working on these mature production wellbores. One revolution that has been in development for the past few decades involves using conventional slickline and electric line to perform light well interventions without the requirement of an offshore drilling or workover rig. This process uses a light well intervention vessel (LWIV) complete with a moonpool located mid-deck for open-sea access, a riserless pressure control package typically involving remotely operated vehicles (ROVs), and a combination of conventional slickline and electric line intervention packages. Interventions using this technology adaptation were primarily developed for the North Sea and Gulf of Mexico regions and have been widely used in those regions. However, after several years of planning, the technology has now been used for the first time to rework several wells for an operator off the east coast of Canada.

Light, riserless, well intervention technologies have been deployed in three individual wellbores offshore Canada. Multiple services were required in each of these three wellbores. Conventional slickline operations were run to prepare each of wellbores, with the retrieval of crown plugs and conventional drift runs. Operations then switched to electric line services to perform diagnostic runs followed by remedial intervention services. Once the electric line services were completed, slickline services were used for safety valve isolations and gas lift remedial work and then returning the newly configured wells back to production mode. The use of the LWIV provided the operator with an efficient intervention technique to evaluate and potentially improve well performance.
A New Approach to In-Service Coiled Tubing Improved Inspection Based Micro-Magnetic Technology
Authors: ZhaoMing Zhou , TaiHe Shi , Runqiao Yu , Fu Wan
Published: March 2015

Mechanical defects are incurred routinely in the coiled tubing (CT), and can have a first order influence on fatigue crack development. Failures of the CT can significantly impact operations and in a worst case can lead to the loss of a well. This paper developed the new non-contact CT assessment system with the new inspection method, which is suitable for the detection in-service and new coiled tubing. This paper proposes a new micro-magnetic detection technology for rapid detection in-service coiled tubing. The method is based on a high precision fluxgate sensor that measures the magnetic field changes in the geomagnetic field, without needing external magnetization and demagnetization to identify the location of the defect. We use iron base amorphous alloy to make the smallerfluxgate sensor. This method is effective in assessing the early damage and developed defects. Eddy current lift-off technique is used for the gap measurement and design ovality detection algorithm. The ovality is obtained through calculation of the software. The optical distance measure sensor measures down to the length of the coiled tubing. The test tool is designed and produced and can be installed and removed fast. 2D imaging is achieved and features the shape of defect. This system is available for various CT diameters. Data acquisition software real-time display flaws curve and the detection imaging. The tool can realize non-contact, measure wall thickness, diameter, ovality, and can fast nondestructively test in-service coiled tubing. The resolution of the testing instrument is 1 mm. It is easy-operating and time-saving, and has the maximum measuring velocity of up to several meters per second. Detection results are close to accurate location of prefabricated corrosion defects through inspection CT test sample. However, as a comparatively new test method, it still has a large room to be improved. Micro-magnetic measurement signals are weak, and its amplitude is small and unperturbed by the environment. Inspection of in-service coiled tubing still need to improve and develop.
Use of Real-Time BHA Data to Enhance Predictability and Safety of Coiled Tubing Solids Removal Operations in New Zealand
Authors: Mallanao Genesis , Saunders Preston , Peralta Javier H
Published: March 2015

Coiled tubing (CT) cleanout operations in New Zealand require extremely detailed planning and execution. When significant proppant is left in the well as a result of hydraulic fracture screenout, customer concern requires ensuring that hydrocarbons are not produced and returned to temporary surface equipment during the cleanout operation. During solids removal, the solid rate of return at surface must be limited to prevent erosion of flowback equipment.

To reduce operator uncertainty during this process, modeling with a solids transport simulator, along with a real-time downhole communication system, was used to provide real-time pressure data at downhole conditions. To provide an engineered cleanout, one of the modeling goals was to determine the predicted maximum solids return rates so the flowback choke integrity was maintained. Real-time monitoring of downhole information during the operation enabled a hydrostatic pressure calculation based on true vertical depth (TVD) to determine the equivalent circulation density (ECD) of the fluid column. Determining the ECD enabled the estimation of the solids concentration in the fluid returned via the annulus (tubing/CT). Consequently, an increase of hydrostatic pressure (relative to water) at downhole conditions correlated to an increase of solids concentration in the fluid column during the cleanout phase. By monitoring this increase in the ECD during the sand cleanout, the operator had an early indication of an increase in solids concentration in the fluid returns. This knowledge enabled the operator to manage the flowback operation at the surface, without exceeding surface equipment specifications. The process met customer requirements for enhanced proppant cleanout operations.

This paper details the background of the operator cleanout requirements, the pre-job design analysis used, the job parameters during execution, and the incorporated improvements made compared with conventional well interventions.
Alloy formation by Mg underpotential deposition on al from nitrate melts
Authors: Cvetkovic Vesna , Bjelica Luka , Vukicevic Natasa , Jovicevic Jovan
Published: March 2015

Magnesium was underpotentially deposited on aluminium electrodes from
magnesium nitrate-ammonium nitrate melts at temperatures ranging from 390 K
to 500 K. Electrochemical techniques used were linear sweep voltammetry and
potential step. Electrodes were studied by Scanning electron microscopy
(SEM), Energy dispersive spectrometry (EDS), energy dispersive X-ray
spectroscopy (EDX) and X-ray diffraction (XRD). It was found that reduction
processes of nitrate, nitrite and water (when present), in the underpotential
range studied, took part simultaneously with magnesium underpotential
deposition. Consequently, magnesium UPD reduction and stripping voltammetry
peaks were not pronounced and well defined. Nevertheless, EDS, EDX and XRD
measurements showed evidence of Mg2Al3, MgAl2 and Al12Mg17 alloys formed by
underpotential deposition of magnesium onto aluminium substrate.
Stock returns, inflation, and real activity in developing countries: A Markov-switching approach
Authors: Cifter Atilla
Published: March 2015

This paper empirically investigates the relationship between real stock
returns, inflation, and real activity using the Markov-switching dynamic
regression (MS-DR) approach. The MS-DR allows multiple structural breaks in
the estimation, and we can check regression coefficients separately in the
recession and expansion periods. We selected two major developing countries
(Mexico and South Africa) in order to reduce location bias. We use real stock
returns, expected inflation, unexpected inflation, and real GDP growth in the
estimations, and the ARFIMA model is used for unexpected inflation. The
empirical results show that the relationship between real stock returns and
inflation is negative only in the recession period. This regime-dependency is
also tested with Eugene F. Fama?s (1981) proxy effect hypothesis, and it is
found that the stock returns respond differently to inflation in a regime
according to the regime-dependent proxy effect hypothesis. These findings
suggest that the negative relationship puzzle in the empirical finance
literature can be explained with the regime-dependency effect.
Income inequality and the business cycle
Authors: Shahee Mostafa
Published: March 2015

This paper first examines the relationship between ordinary least squares
estimators of consumption and investment for 36 selected countries with their
respective Gini indices. The analysis shows that income inequality is
consistent with a smaller estimator of consumption and a greater estimator of
investment. Second, the cycles of GDP, consumption and investment are dated
separately to determine how the deepness and duration of cycles of those
variables are correlated with the Gini indices of countries. The results show
that income inequality leads to a deeper and longer decline of GDP, which
causes a greater cumulative income loss of GDP during recession, and a
somewhat faster speed of recovery during expansion. Likewise, the result of a
correlation between Gini indices and the number of cycles in consumption,
investment and GDP indicate that income inequality is associated with a
greater number of cycles in consumption and GDP and a lower number of cycles
in investment.
Stress, Coping, and Work Engagement within the Specific Job Context: Comment on Kaiseler, et al. (2014)
Authors: Gracia Esther
Published: March 2015

This work discusses the use of tools that make use of context information. Comments are based on a previous study that looked into the relationship between stressors, coping, and work engagement (Kaiseler, Queirós, Passos & Sousa, 2014). A set of propositions are provided for research that will allow the design of contextualized stress interventions in specific job settings.
Relationship of Cognitive Behavioral Therapy Effects and Homework in an Indicated Prevention of Depression Intervention for Non-Professional Caregivers
Authors: Otero Patricia , Væzquez Fernando L. , Hermida Elisabet , Díaz Olga , Torres Ángela
Published: March 2015

Activities designed to be performed outside of the intervention are considered an essential aspect of the effectiveness of cognitive-behavioral therapy. However, these have received little attention in interventions aimed at individuals with subclinical depressive symptoms who do not yet meet diagnostic criteria for depression (indicated prevention). In this study, the completion of tasks given as homework and their relationship with post-treatment depressive symptoms was with relation to an indicated prevention of depression intervention. Eighty-nine female non-professional caregivers recruited from an official registry completed an intervention involving 11 homework tasks. Tasks performed were recorded and depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES–D). Among caregivers, 80.9% completed 9–11 tasks. The number of tasks performed was associated with post-treatment depressive symptoms, with 9 being optimal for clinically significant improvement. These findings highlight the relationship between homework and post-treatment depressive symptoms.
Relationship between Brazilian Adolescents' Physical Activity and Social and Economic Indicators of the Cities Where They Live
Authors: Silva Diego A. S.
Published: March 2015

This study investigated the relationship between sufficient amounts of physical activity among Brazilian adolescents and the economic and social indicators of the cities where they live. Data from a large national survey including 109, 104 boys and girls ages 13 to 15yr. (47.8% boys, 52.2% girls) were analyzed. The economic and social indicators were the Human Development Index (HDI), which is a comparative measure to rank cities according to their degree of human development, the Gini index (income inequality), population density, and maternal education. Stepwise regression was used to identify associations between physical activity and economic and social indicators of the cities. The physical activity of Brazilian adolescents was associated with the social and economic conditions of the cities where they live. The amount of physical activity of girls was greater in the cities with fewer income inequalities. For boys, physical activity was greater in the cities with a higher HDI and fewer income inequalities.
Creating a Positive Learning Environment for Students with English Classroom Anxiety
Authors: Liao Hung-Chang , Wang Ya-Huei
Published: March 2015

Students situated in post-structural feminist pedagogical learning (PFPL) in a freshman English course (37 students) were expected to have lower English classroom anxiety, score higher in English, and have greater satisfaction with the class they attended than those in conventional lecture classes (40 students). Seventy-four students participated in the study ( M age = 18.5 yr., SD = 0.5; 34 men, 43 women). The measures included the English Classroom Anxiety Scale (ECAS), English proficiency tests, the Student Satisfaction Questionnaire (SSQ), and student interviews. After the classes were completed, students in PFPL reported a significant decrease in anxiety toward the English classroom, scored significantly higher on English proficiency, and expressed significantly greater satisfaction with the course. PFPL potentially decreases students' English classroom anxiety and increases their English proficiency.
Evaluation of Peripheral and Focal Vision in Proprioceptive Differentiation of Underfoot Inversion Angles: Comment on Witchalls, et al. (2013)
Authors: Schwabova J. Paulasova , Maly T. , Zahalka F.
Published: March 2015

A study by Witchalls, et al. (2013) mentioned that the addition of focal vision to proprioception testing with walking produces greater proprioceptive acuity than peripheral vision alone (measured ankle proprioception in athletes with or without chronic ankle instability during a stepping task on the Active Movement Extent Discrimination Apparatus; AMEDA). According to this study, people with impaired proprioception, e.g., athletes with chronic ankle instability, may profit from looking down during walking or running. This commentary notes that the active stepping task may not be truly comparable to rhythmic stepping, which is characteristic for walking. In addition, we suggest several amendments to the methodology for further studies related to ankle proprioception measurement, e.g., monitoring of proband eye attention during a stepping task or clear objective evaluation of the subject sample.
Paths with More Turns are Perceived as Longer: Misperceptions with Map-Based and Abstracted Path Stimuli
Authors: Brunyé Tad T. , Mahoney Caroline R. , Taylor Holly A.
Published: March 2015

When navigating, people tend to overestimate distances when routes contain more turns, termed the route-angularity effect. Three experiments examined the source and generality of this effect. The first two experiments examined whether route-angularity effects occur while viewing maps and might be related to sex differences or sense of direction. The third experiment tested whether the route-angularity effect would occur with stimuli devoid of spatial context, reducing influences of environmental experience and visual complexity. In the three experiments, participants ( N = 1,552; M = 32.2 yr.; 992 men, 560 women) viewed paths plotted on maps (Exps. 1 and 2) or against a blank background (Exp. 3). The depicted paths were always the same overall length, but varied in the number of turns (from 1 to 7) connecting an origin and destination. Participants were asked to estimate the time to traverse each path (Exp. 1) or the length of each path (Exps. 2 and 3). The Santa Barbara Sense of Direction questionnaire was administered to assess whether overall spatial sense of direction would be negatively related to the magnitude of the route-angularity effect. Repeated-measures analyses of variance (ANOVAs) indicated that paths with more turns elicited estimates of greater distance and travel times, whether they were depicted on maps or blank backgrounds. Linear regressions also indicated that these effects were significantly larger in those with a relatively low sense of direction. The results support the route-angularity effect and extend it to paths plotted on map-based stimuli. Furthermore, because the route-angularity effect was shown with paths plotted against blank backgrounds, route-angularity effects are not specific to understanding environments and may arise at the level of visual perception.
Laboratory Study of Water Shutoff by Activated Heavy Oil for High Temperature and High Salinity Reservoirs
Authors: Yang Wang , Jijiang Ge , Yonggang Zhang , Guicai Zhang , Wenchao Zhou
Published: March 2015

Activated heavy oil is a favorable blocking agent, because of its good selectivity and recyclability. In this paper, by simulating the reservoir conditions of Tahe Oilfield, the feasibility of water shutoff by activated heavy oil for high temperature, high salinity and high hardness reservoirs has been studied. Based on the reservoir characteristics, a nonionic-anionic compound emulsifier of 2 % MZ-18 + 3 % BH-12 (MZ-18 = nonionic amide emulsifier condensed by long chain carboxylic acid and polyethylene polyamine; BH-12 = anionic sulfonate emulsifier) was screened out as the optimum emulsification system for the activated heavy oil. The W/O emulsion prepared by the activated heavy oil is of high viscosity; besides, its temperature resistance, salinity tolerance and thermal stability were competent to Tahe reservoir. The water shutoff performance of activated heavy oil was evaluated by the physical simulation experiments. The results show that the activated heavy oil can improve the water shutoff performance and flushing resistance performance in a wide range of permeability – from 300 to 1 500 mD. Also it is found that, the water shutoff ability of the activated heavy oil increases with the increase of permeability of the sands, injection rate of blocking agent as well as the displacing rate of displacement fluid.
Electrokinetic Potentials of Cotton Fabrics Dyed and Finished in Presence of LAS and Alkyl Polyglucosides and Dye Transfer Inhibitor
Authors: Carrión-Fité Francisco J.
Published: March 2015

In this work we aimed our focus at the determination of the zeta potentials of a standard fabric of cotton Empa type (dyed, finished and softened), which was washed in the presence of surfactants and of a copolymer of action DTI – dye transfer inhibition agent –. The copolymer DTI the type VI/PVP, was used. The washing with ecological surfactants such as: a sodium dodecylbenzene sulfonate (LAS) mixed with an non-ionic alkylpolyglucoside (APG) was made. The cotton fabric was dyed with three different direct dyes (with different molecular weights), finished by the resin of DMDHEU (dimethylol dihydroxy ethylene urea) and softened with a microemulsionated compound of ammoniumsilicone. The variation of zeta potential of cotton articles was obtained under the influence of the total concentration and the proportion of mixture of the surfactants anionic with non-ionic, and of these separately. The polymer DTI stayed to constant concentration, when mixing it with the surfactants. The variation of the zeta potentials of the cotton undyed and finished in function of the DTI were obtained.
Production cross–section calculations of medical 32P, 117Sn, 153Sm and 186,188Re radionuclides used in bone pain palliation treatment
Authors: Demir B. , Kaplan A. , Çapalı V. , Sarpün İ. H. , Aydın A. , Tel E.
Published: March 2015

In this study, production cross–section calculations of 32P, 117Sn, 153Sm and 186,188Re radionuclides used in bone pain palliation treatment produced by 30Si(d,γ)32P, 118Sn(γ,n)117Sn, 116Sn(n,γ)117Sn, 150Nd(α,n)153Sm, 154Sm(n,2n)153Sm, 152Sm(n,γ)153Sm, 186W(d,2n)186Re, 187Re(γ,n)186Re, 185Re(n,γ)186Re and 187Re(n,γ)188Re reactions have been investigated in the different incident energy range of 0.003–34 MeV. Two-component exciton and generalised superfluid models of the TALYS 1.6 and exciton and generalised superfluid models of the EMPIRE 3.1 computer codes have been used to pre-equilibrium (PEQ) reaction calculations. The calculated production cross–section results have been compared with available experimental results existing in the experimental nuclear reaction database (EXFOR). Except the 118Sn(γ,n)117Sn, 150Nd(α,n)153Sm and 185Re(n,γ)186Re reactions, the two-component exciton model calculations of TALYS 1.6 code exhibit generally good agreement with the experimental measurements for all reactions used in this present study.
Evaluation of advanced displacement cross-sections for the major EUROFER constituents based on an atomistic modelling approach
Authors: Konobeyev A. Yu. , Fischer U. , Pereslavtsev P. E.
Published: March 2015

The displacement cross-sections were evaluated for main components of EUROFER at the energies of primary neutrons up to 150 MeV. The number of primary defects was calculated using an advanced binary collision approximation model applying results of molecular dynamics simulations. The cross-sections obtained were processed into ENDF and ACE formatted data and tested using the MCNP code.
3D reconstruction and characterization of carbides in Ni-based high carbon alloy in a FIB-SEM system
Authors: Bala Piotr , Tsyrulin Katja , Jaksch Heiner , Stepien Milena
Published: March 2015

Dual beam focused ion beam scanning electron microscopes (FIB-SEMs) are well suited for characterizing micron and submicron size microstructural features in three dimensions throughout a serial-sectioning experiment. In this article, a FIB-SEM instrument was used to collect morphological, crystallographic, and chemical information for an Ni–Ta–Al–Cr alloy of high carbon content. The alloy has been designed to have excellent tribological properties at elevated temperatures. The morphology, spatial distribution, scale, and degree of interconnection of primary carbides in the Ni–Ta–Al–Cr–C alloy was assessed via serial sectioning in a casting cross-section. The 3D reconstructions showed that the primary carbides and dendrites were forming a dendrite surrounded by primary carbide network over the entire cross-section. Additionally, the morphology and spatial distribution of secondary carbides after heat treatment was determined.
Influence of casting procedure on microstructure and properties of Mg alloy–glassy carbon particle composite
Authors: Olszówka-Myalska Anita , Myalski Jerzy , Chrapoński Jacek
Published: March 2015

The article presents the microstructure and properties of a new cast composite material with a magnesium alloy matrix (Zn 0.7 wt.%, Zr 0.06 wt.%, Nd 0.41 wt.%, Gd 0.21 wt.% and Mn 0.03 wt.%) and glassy carbon particles (10 wt.%, granulation 70–100 μm), dedicated to a technical application under dry friction conditions, manufactured under industrial conditions from a particle–metal suspension. Microstructural examination revealed that the pressure die casting method eliminates the microvoids formed in the gravity cast process both in the matrix and at the interface and also that it decreases the effect of Zr and other phases accumulating around the particles. The applied procedure of particle extraction from the composite's matrix, followed by scanning electron microscopy examination with energy dispersive spectroscopy, revealed the influence of Nd and Gd on the microstructure of the particle–matrix interface. The results of the mechanical and tribological properties tests showed that the application of pressure die casting method for the processing of Mg–GCp composite products improved those properties.
Microstructure and interfacial reactions in the bonding zone of explosively welded Zr700 and carbon steel plates
Authors: Paul Henryk , Morgiel Jerzy , Faryna Marek , Prażmowski Mariusz , Miszczyk Magdalena
Published: March 2015

The microstructure of an explosive cladding joint formed between parallel Zr700 alloy and carbon steel plates was examined with the use of scanning and transmission electron microscopes equipped with energy dispersive spectrometry. The study focused on near-the-interface microstructural changes and possible interdiffusion between the plates. At the macro-scale, the interfaces were outlined by a characteristic sharp transition, indicating that there was no mechanical mixing between the welded metals in the solid state. At the micro-scale, the melted zones often showed non-uniform swirl-like areas of a similar contrast. The nano-scale analysis revealed that the melted areas were composed of mixed amorphous and nano-crystalline phases. The bonding was always achieved by way of surface melting of the joined materials, which might be invisible for observation methods other than transmission electron microscopy.
Development of new spectrophotometric method for estimation of tenofovir disoproxil fumarate using MBTH reagent
Authors: Varsha Mannem Sri , Babu N. Raghavendra , Padmavathi Yenumula , Kumar P. Ravi
Published: March 2015

A new simple, sensitive and specific procedure has been developed for determination of tenofovir disoproxil fumarate in bulk and pharmaceutical dosage forms using MBTH reagent. The purpose of this analytical validation procedure is to validate it by laboratory experiments to prove that the method meets the minimum standards for laboratory use. 3-methyl-2-bezothiazoline hydrazone reacts with the secondary amine group of tenofovir in the presence of oxidizing agent, ferric chloride. The resulting apple green coloured chromogen when measured spectrophotometrically in visible region (i.e., 400-800nm) shows a maximum absorbance at 626.5nm. This method can be successfully applied for the determination of drug content in pharmaceutical formulations. The results of analysis have been validated statistically.DOI: http://dx.doi.org/10.3329/icpj.v4i4.22620 International Current Pharmaceutical Journal, March 2015, 4(4): 378-381
Evaluation of growth of Chlorella ellipsoidea in different culture media
Authors: Jahan F , Rahman MS , Hossain MA
Published: March 2015

An experiment was conducted to evaluate the growth of Chlorella ellipsoidea in three different media viz,. medium I (pulse bran), medium II (soil extract) and medium III (inorganic) under the natural environmental conditions. The alga, C. ellipsoidea, reached maximum cell density of 56.32 × 106 cells ml-1 in 10 days in medium I (pulse bran), maximum cell density of 102.99 × 106 cells ml-1 in 11 days in medium II (soil extract) and maximum cell density of 64.23 × 106 cells ml-1 in 12 days in medium III (inorganic medium). The ranges of water temperature, air temperature and light intensity were 22 to 32ºC, 22 to 34ºC and 2.11 to 4.31 (× 103) lux, respectively during the culture period. The average sunshine period was 7.65 ± 1.57 hours. Total alkalinity, free CO2, pH, NO3-N, PO4- P of algal culture medium I, medium II and medium III were 220, 200 and 150 mg L-1 ; 26, 9 and 19 mg L-1; 7.9, 7.6 and 7.5; 45, 45 and 133.33 mg L-1; 10.9, 15.1 and 37.06 mg L-1, respectively. Cell densities of cultures of C. ellipsoidea under three treatments I, II and III, it can be concluded that cell densities under 3 treatments are significantly different (F=39.78) and treatment II (soil extract medium) is the best for algal (C. ellipsoidea) culture among three treatments. DOI: http://dx.doi.org/10.3329/ijarit.v4i2.22636 Int. J. Agril. Res. Innov. & Tech. 4 (2): 6-10, December, 2014