bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing Scale Inhibitor Squeeze Retention With Additives
Authors: Sutherland Louise , Jordan Myles
Published: April 2016

The practice of scale squeeze treatments to oil/gas production wells to prevent inorganic scale formation has been applied for over 30 years and during that period of time different mechanisms to retain the inhibitor chemical have been evaluated. The simple mechanism of inhibitor retention adsorption/desorption has been complemented over the years by enhanced adsorption via mutual solvent and full precipitation of the active inhibitor as calcium salt onto the mineral surface of the reservoir.

This study has been conducted to understand if the retention of phosphonate and phosphate ester inhibitors can be improved by adsorption of a charged polymer onto the rock prior to application of the scale inhibitor or if application of the same polymer enhancer after adsorption of the scale inhibitor will extend squeeze life. These tests have been carried out using pack floods at 85°C with synthetic North Sea produced water and the details of the extension in treatment life observed are correlated to the inhibitor type tested and the sequence of application of the polymer enhancer. This study shows how the different functional groups within the scale inhibitors interact with the mineral surface and polymer enhancer to extend treatment lifetimes and so potentially reducing the frequency of squeeze treatments and therefore total cost of operations.
A Thermodynamic Model for The Solution Density and Mineral Solubility Predictions up to 250 °C, 1,500 Bars for Na-K-Mg-Ca-Ba-Sr-Cl-CO3-HCO3-SO4-CO2 aq Systems
Authors: Dai Zhaoyi , Kan Amy T. , Zhang Fangfu , Yan Fei , Ruan Gordon , Bhandari Narayan , Zhang Zhang , Liu Ya , Al-Saiari Hamad A. , Tomson Mason B.
Published: April 2016

Deep water oil and gas production is playing an important role in global energy support. With the advancement of deep water offshore production in recent years, there are more chances encountering with the extreme conditions of high temperature (up to 250 °C), high pressure (up to 1,500 bars) and high TDS (up to halite saturated salinity) in the presence of mixed electrolytes. Scale control in such environment requires accurate prediction of scale formation tendency. However, most previous models are not capable of predicting the scale mineral solubilities over such wide ranges of temperature, pressure and ionic strength. Pitzer theory is one of the most advanced thermodynamic models for the predictions of mineral solubility and other thermodynamic properties. However, the published Pitzer models often have limited ranges of applicability and potential inconsistencies with each other. In this paper, the published Pitzer models have been thoroughly reviewed to evaluate the consistencies of Pitzer parameters among these published models. In addition, more than 5,000 density and solubility experimental data published in the past 150 years were collected as the input database for model fitting to extend the applicable ranges. These experimental data were fitted through the determinations of standard partial molar volume (V0¯) of each ion and the virial coefficients for species specific short range interactions as functions of temperature and pressure. The developed model is capable to predict the density of soluble chloride and sulfate salt solutions within ±0.1% relative error, common scale mineral saturation index (SI = lg(IonActivityProduct/Ksp) within ±0.1 units under most conditions, CO2 solubility in NaCl and CaCl2 solutions within 0.7% relative error of 95% confidence interval. The developed model has been incorporated into ScaleSoftPitzer for practical use in the oil and gas fields, along with the flash calculator based on Peng-Robinson EoS, which can accurately predict the species partitioning in oil/water/gas phases.
Modelling CaCO3 Scale in CO2 Water Alternating Gas CO2-WAG Processes
Authors: Silva D. , Sorbie K. S. , Mackay E. J.
Published: April 2016

CO2 Water Alternating Gas (CO2-WAG) is one of the main Enhanced Oil Recovery (EOR) techniques which is currently being implemented in the emerging pre-salt projects offshore Brazil. CO2-WAG consists of the alternated injection of CO2 and water in the reservoir for tertiary oil recovery. However, this process may lead to the enhanced deposition of CaCO3 in production wells. This may occur since, in a CO2-WAG scheme, CO2 dissolves in the water slug causing a decrease in the pH. At lower pH levels, carbonate rock is dissolved causing an increase in the carbon and calcium content in the water slug. As fluids are later produced, the operating pressure is reduced and dissolved CO2 is evolved from solution, causing an increase in the pH. At these less acidic pH levels, CaCO3 may become oversaturated and precipitate.

In order to address each process involved in CaCO3 formation, an integrated modelling approach between aqueous scale prediction modelling, Vapour-Liquid Equilibria (VLE) modelling and reservoir modelling is proposed. In particular, acid equilibria and precipitation reactions coupled with the Pitzer equations are used to build the scale prediction model. The facility to calculate CaCO3 co-precipitation with other minerals, such as BaSO4, FeCO3, FeS, etc., is also introduced. Five different equations of state (namely SRK, PR, PRSV, PT and VPT) are used in VLE calculations to model the solubility of CO2 (or a mixture of CO2, H2S and CH4) in brine. To model the reactive flows in the reservoir, the advection-diffusion equation is coupled with the scale precipitation equations. The reactive transport model addresses carbonate rock-brine interactions and fluid flow through a porous medium. Once integrated in one single model, these equations have been shown to address all steps in CaCO3 formation relevant for CO2-WAG, i.e., the geochemical processes taking place in the reservoir and at the production wells, thus capturing the full dimension of the scaling problem. In addition, the proposed model has been successfully validated with experimental data on the injection of seawater adjusted to various pH levels into a CaCO3 packed column. The measured effluent pH levels and calcium concentrations were used to validate the model.
Least Square Support Vector Machine: An Emerging Tool for Data Analysis
Authors: Panja Palash , Pathak Manas , Velasco Raul , Deo Milind
Published: April 2016

Development of high speed computing leads to major advancements in every field of science and engineering. Artificial intelligence (AI) method is emerging as new modern technology applied to machine learning, pattern recognition, processing and understanding data, robotics etc. Its application in oil and gas industry is new despite of the fact that it has huge potential to explore the knowledge regarding reservoir characterization, PVT properties estimation, maximize productions, locating sweet spot using pattern recognition, optimum design of fracturing job, calculation of recoverable hydrocarbon, well placement etc. The main objective of this study is to put AI such as LSSVM in perspective from reservoir engineering and encourage engineers and researchers to consider it as a valuable alternative tool in the petroleum industry. Factors most affecting the production from fractured low permeability reservoirs such as reservoir permeability, gas relative permeability exponent, rock compressibility, initial gas oil ratio, slope of gas oil ratio in PVT, initial pressure, flowing bottom hole pressure and fracture spacing, are studied. A wide range of values of each parameter based on real field data from Eagle Ford, Bakken and Niobrara in the USA are assigned. Two different kinds of mathematical surrogate models, polynomial response surface method (RSM) and least square support vector machine (LSSVM) are compared to seek the better surrogate models in terms of predictability. Data are generated from a generic reservoir model using commercial simulator. Various models of recovery factors and gas oil ratio are developed for different times (after 90 days, 1 year, 5 years, 10 years, 15 years and 20 years) and for a minimum economic rate (5 STB/ day). Multivariate regression was used to obtain coefficients for the second-order polynomial response surface models using 80% of the simulated results (144). The LSSVM models coupled with radial basis kernel function (RBF) are trained with 60% data. 20% of data is used to tune the regularization parameter and kernel parameter using genetic algorithm (GA) optimization routine. Rest 20% data is utilized for testing the models' predictability for future performance. Goodness of fit is statistically measured by calculating coefficient of determination (R2), normalized root mean square error (NRMSE) and average absolute relative error (AARE). LSSVM exhibits good predictability to forecast the production such as oil recovery, gas recovery as surrogate models. The developed models can be used with high accuracy to forecast the production of oil from ultra-low permeability reservoirs. Quick sensitivity analysis of oil recovery to any parameter used in this study can be performed. The models are also useful for uncertainty analysis of productions.
Effects of Hydraulic Fractures on the Treatment of Condensate by Huff-n-Puff Gas Injection in Eagle Ford Shale
Authors: Yang S. , Wei Y. , Chen Z. , Wu W. , Ji D.
Published: April 2016

With the production of a gas condensate tight reservoir, condensate in fracture can significantly decrease the productivity of gas condensate wells. Previous work shows that the negative effect of condensate bank on gas production is more seriously in tighter reservoir. The implement of hydraulic fracture and multi-stages fracturing can mitigate the negative effects on the formation of condensate bank, but the effects cannot be completely removed. A huff-n-puff methane injection has been proven to be an effective method to reduce the effect of condensate by maintaining the reservoir pressure above the dew-point pressure and revaporizing the formed condensate. However, the previous work neglects the effect of hydraulic fractures on the treatment of condensate by gas injection.

Non-aqueous components are lumped into fourteen pseudo components. Dual permeability, logarithmically spaced, locally refined grids are implemented to model natural and hydraulic fractures in a simulation model. The laboratory measured relative permeability taking account of condensate bank is used to accurately represent two-phase flow in a shale reservoir. Furthermore, two different settings of cyclic schedule are implemented to test their advantages and disadvantages.

The results show that the huff-n-puff dry gas injection can effectively improve gas and condensate recovery. A fracture conductivity has significant influences on well production during the injection, while during the primary recovery its impact is not that obvious. In addition, the huff-n-puff schedules also plays a crucial role in both gas and condensate recovery. Our study highlights gas injection mitigates the effect of condensate bank on gas production in a shale reservoir, and provides an extensive insight on optimal design of Huff-n-Puff gas injection.
Integrated Reservoir Modeling Workflow That Couples PVT and Adsorption in Confined Nano-Pores, An Eagle Ford Application
Authors: Wu Xingru , Zhou Guangqing , Najobaei Bahareh , Pu Hui , Li Yinghui
Published: April 2016

Enhanced oil recovery techniques are having a growing interest for unconventional reservoirs to attack the low primary recovery factor issue, especially in a low oil price environment. Tight oil behaves a quick decline without much pressure support and thus jeopardies project profitability given a large initial capital requirement for horizontal drilling and massive multi-stage hydraulic fracturing operations. However, over 90% oil is still left behind in stimulated reservoir volume. It is imperative to understand the differences in production drivers in unconventional reservoirs, especially using EOR techniques, for example, how capillarity and adsorption may greatly alter phase behavior in nano-size pores.

Previous studies showed that phase behavior and production mechanisms might be significantly different under nano-scale pore confinement in organic matter in Eagle Ford formation. This research was to shed light to quantify such differences under the influce of large capillary forces in organic and inorganic pores integrating petrographic and/or petrophysical measurements, for example, mercury injection capillary pressure (MICP) experiments. Further, this study developed a new methodology to consistently evaluate the effect of adsorption at the same pore size distribution as capillary evolved.

Results showed that a large difference of phase and adsorption behavior existed for unconventional reservoirs in the oil window in the Eagle Ford formation, and pore size distribution played an important role in quantifying such differences. This may lead to additional rock-typing techniques to better characterize the Eagle Ford oil play and improve well expected ultimate recovery (EUR) and economics.
Phase Behavior of Multicomponent Hydrocarbons in Organic Nanopores Under the Effects of Capillary Pressure and Adsorption Film
Authors: Dong Xiaohu , Liu Huiqing , Hou Jirui , Chen Zhangxin , Wu Keliu , Zhan Jie
Published: April 2016

The presence of nanopores in tight rocks and shales have been confirmed by numerous studies. These pores are also the primary storage space of oil and gas in shales. Due to the effect of nanoscale confinement, the phase behavior of fluids confined in such extra-low permeability formation (nanodarcy scale) differs significantly from those observed in the conventional formation.

In this paper, the cubic PR EOR is coupled with the capillary-pressure equation and adsorption theory to investigate and represent the phase equilibria of pure components and their mixtures in cylindrical nanopores. The pore confinement effects of interaction between fluid molecule and pore wall and the shift of critical properties are all considered. Also due to the effect of adsorption film, an improved Young-Laplace equation is adopted to simulate the capillarity instead of the conventional equation. For the adsorption behavior, the experimental data on the adsorbent of silicalite are used to represent the adsorption behavior of hydrocarbons in nanopores. Then, a prediction process for the behavior of methane, n-butane, n-pentane, n-hexane and their mixtures are performed. And the results are compared against the available experimental data to confirm the accuracy of this scheme. The actual Eagle Ford oil is also used to examine the performance of our scheme.

Results indicate that the presence of adsorption film could further increase the vapor-liquid equilibrium constant (K-value) and capillary pressure of the confined pure-component fluid, especially for the nanopores with few nanometers. The smaller the nanopore radius, the higher the deviation between the actual K-value and bulk value. For methane, when the pore radius is higher than about 20 nm, the K-value is approaching the bulk fluids and the effect of capillary pressure and adsorption film can be neglected. For n-pentane, it is about 18 nm. For binary mixture, it is found the higher the difference between the two components, the stronger the nanopore confinement effects. The capillary pressure will present a bilinear relation with the pore radius in the log-log plot. For multicomponent mixture, as the pore radius decreases, the bubble-point pressure is depressed, the dew-point pressure is increased, and the phase envelop of confined fluids is also shrinked. When the adsorption film is neglected, the bubble-point pressure will be overestimated, and the dew-point pressure is underestimated. For Eagle Ford oil, when the nanopore radius is higher than about 100 nm, the behavior will approach the bulk value and the influence of nanopore confinement can be neglected. This study will shed some important insights for the phase behavior of tight oil and gas condensate in nanopores.
Effects of Nanoscale Pore Confinement on CO2 Immiscible and Miscible Processes
Authors: Zhang Kai , Kong Bing , Zhan Jie , He Ruijian , Qin Tianjie , Wu Keliu , Chen Zhangxin , Chen Shengnan , Zhang Jiaming
Published: April 2016

CO2 flooding is a promising technique for improving oil recovery in tight oil reservoirs. Because of existence of nanoscale pores in tight oil reservoirs, which can affect phase equilibrium, there will be some variations between CO2 immiscible and miscible processes in conventional and tight oil reservoirs. In this paper, the effects of nanoscale pore confinement on CO2 immiscible and miscible processes are studied.

On the basis of Cardium crude oil composition, phase equilibrium at various nanoscale pore radii is investigated. Since the interfacial tension is related to capillary pressure, it can be scaled in normalized oil recovery calculations. Furthermore, a reservoir can be assumed an immiscible zone, a miscible zone, or an unswept zone during CO2 injection. In this case, nanoscale pore confinement on CO2 immiscible and miscible processes can be evaluated.

Taking the nanoscale pore confinement into consideration, the tie line length and interfacial tension can be reduced, which contribute to a lower CO2 minimum miscible pressure (MMP). In this way, the efficiency of CO2 immiscible flooding is improved, while the efficiency of miscible flooding is not affected by a confinement effect. Furthermore, the length of a CO2 immiscible zone can be decreased by nanoscale pore confinement.
Effect of Methane Adsorption on Stress-Dependent Porosity and Permeability in Shale Gas Reservoirs
Authors: Pang Y. , Soliman M. Y. , Deng H. , Emadi Hossein
Published: April 2016

Although stress-dependent porosity and permeability have been applied to majority of models to calculate effective porosity and permeability, effect of adsorbed gas specified as pore volume occupied by adsorbate is not properly accounted. However, nanoscale porosity and permeability of shale rocks would be significantly reduced, since the pore volume is occupied by layers of adsorbed gas molecules.

In this paper, we combine stress and adsorption effects to establish a new correlation of shale porosity and permeability. We calculate the stress-dependent pore volume with a constant pore compressibility and obtain the volume of adsorbate from doing regression analysis for density of adsorbed gas by Dubinin-Astakhov (D-A) equation under the supercritical condition. Lab experiments for methane adsorption in shale are measured by five real core samples. The data of Gibbs adsorption obtained by experiments is converted to absolute adsorption so that it could be used to generate the correlation of stress-dependent porosity and permeability including consideration of adsorption effect.

The new generated correlation illustrates that the trend of changes in porosity and permeability with pore pressure is quite similar to the trend calculated by Shi-Durucan (S-D) model in application to coalbed methane, which indicates that porosity and permeability decrease with the increase of pore pressure. This tendency is the inverse of changes in stress-dependent porosity and permeability in relation to pore pressure, which demonstrates that adsorption has a larger influence on pore volume than stress, because more gas attempts to adsorb on surface area of matrix as pore pressure increases. The new correlation is added into a numerical model in field-scale, which successfully matches production data from a horizontal well with multistage hydraulic fractures in Barnett shale reservoir. The simulation results point out that without considering the impact of pore volume occupied by adsorbed gas, cumulative gas production would be greatly overestimated during economical producing period in shale gas reservoirs.

Thus, overestimation of porosity and permeability in shale might be avoided by applying the new correlation considering both stress and adsorption effects. The correlation incorporated into numerical simulators could provide accurate estimation and evaluation of gas production.
A Multi-Scale Imaging and Modeling Workflow for Tight Rocks
Authors: Ruspini L. C. , Lindkvist G. , Bakke S. , Alberts L. , Carnerup A. M. , Øren P. E.
Published: April 2016

Heterogeneous rocks with broad pore size distributions, such as carbonates and clay-rich sandstones, often display widely varying behavior. The interaction of micro- and macro-porosity in these complex rocks makes them difficult both to understand and to characterize. Pore scale imaging and modeling has the potential to greatly improve our understanding and predictive capabilities of these complex rocks. However, a single imaging technique can rarely capture the relevant length scales in desired detail due to restrictions of image size vs. resolution. Similarly, direct simulations of transport properties in heterogeneous rocks with broad pore size distributions are prohibitively expensive computationally.

In the present work we present a multi-scale imaging and modeling workflow to compute transport properties of rocks with wide pore size distributions. A dry/wet micro-CT imaging sequence is used to spatially map the porosity distribution and connectivity of macro- (i.e. resolved) and micro-porous (i.e. sub-resolution) regions. The registered 3D porosity map is transformed into a multi-scale pore network model where macro-porosity regions are modeled in a conventional pore network manner while micro-porous network elements are treated as a continuous porous medium. The necessary input parameters to characterize the micro-porous elements are computed from high resolution BSE images of different micro-porosity regions.

The multi-scale workflow was applied to two samples of tight sandstones. Computed petrophysical properties as well as capillary pressure and relative permeability relationships are compared with available experimental data. The agreement between computed and measured results is encouraging. The results clearly demonstrate that the distribution and connectivity between macro- and micro-porosity regions control the observed transport properties.
Improved Hole Size Calculated from Cement Data in Williston Basin
Authors: Sheperd Paul , Noman Sarah , Beery William , Bridge Alexander
Published: April 2016

The intermediate casing hole size can be calculated from empirical data in the Williston basin. Using this calculation reduces the cement excess required, helps achieve the top of cement objectives, and reduces the cementing costs. Many operators in the Williston basin are using an outdated assumption of average hole size for calculation of cement volumes on their intermediate casing section. This results in excessive cement volumes to sometimes detrimental effect; breakdown is occurring frequently at the Mission Canyon. This occasionally causes operators to fail to meet cementing job objectives. Very few open hole calipers are run in the intermediate section in this basin, making direct measurements very rare.

In an extensive review, cement evaluation logs from approximately 300 wells in a 15-month period from January 2014 through March 2015 were used to approximate top of cement and then derive an average effective hole size. The logs evaluated were from cement bond log (CBL) and ultrasonic imaging tools. The data are controlled in a statistical manner for cement job anomalies such as losses or severe channeling.

The findings prove that intermediate casing hole size in the Williston basin is much smaller today than in the recent past. The switch from water-base mud to oil-base mud and a marked improvement in drilling speed have limited the size of the intermediate section hole. One operator was able to substantially reduce cement volumes, keeping the top of tail slurry a minimal height above the weakest formation and thus avoiding losses. As a result, this operator is achieving top of cement objectives more frequently and has substantially reduced cementing cost.

This analysis contributes to the community valuable empirical data about intermediate section hole size in the Williston basin using a large dataset and statistical controls to ensure quality of the conclusions.
Long–Term Renal Outcomes after Cisplatin Treatment
Authors: Latcha Sheron , Jaimes Edgar A. , Patil Sujata , Glezerman Ilya G. , Mehta Swati , Flombaum Carlos D.
Published: April 2016

Background and objectives

Nephrotoxicity remains the dose–limiting side effect of cisplatin, an effective chemotherapeutic agent with applications across diverse tumor types. This study presents data on renal outcomes across multiple tumor types in 821 adults. We report on incidence of AKI, initial and long-term changes in eGFR after cisplatin, and relationships between cumulative dose, initial eGFR, age, sex, and long–term renal function.

Design, setting, participants, & measurements

This was a retrospective study of adult patients treated with cisplatin from January 1, 2000 to September 21, 2011 who had survived ≥5 years after initial dose. The Modification of Diet in Renal Disease equation was used to calculate eGFR. AKI was defined as an increase from the baseline creatinine of >25% within 30 days after the first cycle of cisplatin. Chi-squared tests were done to evaluate the relationships between categorical or ordinal variables; ANOVAs or t tests were used to evaluate continuous or categorical variables. Changes in eGFR over time were evaluated in a growth curve model.

Results

Mean follow-up was 6 years (25th and 75th percentiles, 4 and 9 years). AKI occurred in 31.5% of patients, with a median initial decline in eGFR of 10 ml/min per 1.73 m2 (25th and 75th percentiles, −41.5 and −23.3 ml/min per 1.73 m2). At any time point after the first cycle of cisplatin, <3% of patients progressed to eGFR<29 ml/min per 1.73 m2, and none were known to be on dialysis. Age was associated with a higher risk for AKI after cisplatin. Compared with age <25 years old, the odds ratios for AKI versus no AKI are 1.22 for >26–44 years old (95% confidence interval [95% CI], 0.60 to 2.4), 1.54 for >45–65 years old (95% CI, 0.78 to 3), and 2.96 for >66 years old (95% CI, 1.4 to 6.1). The lowest dose categories of cisplatin (≤100 and 101–250 mg/m2) are associated with increases in eGFR (P=0.06 and P=0.02, respectively) compared with the highest dose category (>701 mg/m2).

Conclusions

This is the largest study of adult patients with cancer who received cisplatin for treatment across multiple tumor types. Most patients experience small but permanent declines in eGFR, but none progressed to ESRD requiring hemodialysis.
Innovation and a Return to the Status Quo
Authors: Strunk Katharine O. , Marsh Julie A. , Hashim Ayesha K. , Bush-Mecenas Susan
Published: April 2016

School reconstitution, a turnaround strategy that prescribes massive staffing turnover, is expected to result in more committed and capable school staff and innovative practices. However, little evidence supports this assumption. We use quasi-experimental designs to assess the impact of reconstitution on student achievement and teacher mobility, finding that reconstitution affected teacher mobility and improved student achievement in the first year of the reform, with continued but smaller impacts in the out years. We draw on mutual learning theory to conduct an exploratory analysis of reform implementation. We find that initial re-staffing and strategic planning may have promoted balance between exploring new and exploiting existing knowledge. Over time, however, balanced, mutual learning was not sustained.
After dispossession
Authors: Salemink Oscar , Rasmussen Mattias Borg
Published: April 2016

Since the 1980s globalization has taken on increasingly neoliberalizing forms in the form of commoditization of objects, resources, or even human bodies, their reduction to financial values, and their enclosure or other forms of dispossession. “After dispossession” provides ethnographic accounts of the diverse ways to deal with dispossessions by attempts at repossessing values in connection to what has been lost in neoliberal assemblages of people and resources and thus how material loss might be compensated for in terms of subjective experiences of restoring value beyond the financial. The analytical challenge we pursue is one of bridging between a political economy concerned with the uneven distribution of wealth and resources, and the profound changes in identity politics and subject formation that are connected to these. We therefore argue that any dispossession may trigger acts of repossession of values beyond the financial realm, and consequently that suffering, too, entails forms of agency predicated on altered subjectivities. This move beyond the suffering subject reconnects the study of subjectivities with the analysis of alienation, disempowerment, and impoverishment through dispossession and attempts at recapturing value in altered circumstances.
Infrastructures of progress and dispossession
Authors: Andersen Astrid Oberborbeck
Published: April 2016

This article examines what economic growth and state versions of progress
have done to small and medium-scale farmers in an urban setting, in Arequipa
in southern Peru. The general reorganization of production, resources, and
labor in the Peruvian economy has generated a discursive move to reposition small
and medium-scale farmers as backward. This article analyzes how farmers struggle
to find their place within a neoliberal urban ecology where different conceptions of
what constitutes progress in contemporary Peru influence the landscape. Using an
analytical lens that takes material and organizational infrastructures and practices
into account, and situates these in specific historical processes, the article argues
that farmers within the urban landscape of Arequipa struggle to reclaim land and
water, and reassert a status that they experience to be losing. Such a historical focus
on material and organizational infrastructural arrangements, it is argued, can
open up for understanding how local and beyond-local processes tangle in complex
ways and are productive of new subjectivities; how relations are reconfigured
in neoliberal landscapes of progress and dispossession. Such an approach makes
evident how state and nonstate actors invest affects, interests, and desires differently
within a given landscape.
Foregrounding possibilities and backgrounding exploitation in transnational medical research projects in Lusaka, Zambia
Authors: Bruun Birgitte
Published: April 2016

Today medical research funded by resourceful commercial companies and philanthropic organizations increasingly takes place in much less resourceful settings across the globe. Recent academic studies of this trend have observed how global inequalities have shaped the movements of this research, and how human subjects who make their blood and bodies available are at risk of exploitation. In Lusaka, people expressed their fears of being used by transnational medical research projects in various idioms of concern. While such concerns were always latent, people were generally eager to join the projects. Concerns were often backgrounded in favor of pragmatic attention to—and active creation of—possibilities that might stretch well beyond the purpose and time limit of individual research projects. The article illuminates how intimately the ambiguities and possible scenarios of exploitation inherent in transnational medical research projects are intertwined with scenarios of possibility.
Humanitarian mine action in Myanmar and the reterritorialization of risk
Authors: MacLean Ken
Published: April 2016

This article examines current debates for and against Humanitarian Mine Action (HMA) in Myanmar. The analysis, based on interviews with key local, national, and international actors involved in HMA, reveals why so many of them regard the mapping and removal of “nuisance” landmines as posing a security threat to the peace process. (Landmines deny people access to territory; when conflict ends, these landmines no longer serve a strategic purpose and thus become a dangerous nuisance.) These same debates also shed light on the growing role risk management approaches now take in Myanmar as a response to decades of authoritarian misrule by a succession of military regimes. The landmines, although buried in the ground, actively unsettle such good governance initiatives and the neoliberal development projects to which they are often linked, most often by reterritorializing military, humanitarian, political, and economic authority in overlapping and conflicting ways at multiple scales. The findings reveal why HMA actors resist labeling the crisis landmine contamination poses to civilians as a “crisis” that requires immediate humanitarian action.
Antifungal activity and brine shrimp toxicity assessment of Bulbine abyssinica used in the folk medicine in the Eastern Cape Province, South Africa
Authors: Kibiti Cromwell Mwiti , Afolayan Anthony Jide
Published: April 2016

Bulbine abyssinica is widely used in folk medicine in Eastern Cape Province, South Africa. The aim of this study was to evaluate the antifungal and toxicity potentials of essential oil, acetone and aqueous extracts of this species using standard procedures and brine shrimp test, respectively. The results showed that the species was active against the growth of Microsporum canis, Microsporum gypseum and Trichophyton rubrum among the evaluated opportunistic fungi. The toxicity results showed that the lowest cysts hatching success was observed with the essential oil, then acetone extract, with aqueous extract exhibiting the highest hatching success. Based on the criterion of toxicity indices of the lethality test, all the plant fractions exhibited LD50 values greater than 1 mg/mL hence are non-toxic. These findings indicate that B. abyssinica is a good source of antifungal agents.

 
Intensification of Mediterranean Goat Production Systems: A Case Study in Northern Morocco
Authors: Godber Olivia , Laroussi Boughaleb , Chentouf Mouad , Wall Richard
Published: April 2016

Goats are important contributors to both food and financial security of the resource poor, particularly in marginal environments such as those in the Mediterranean region. To fully understand the feasibility and potential consequences of any intensification or husbandry changes that could contribute to higher outputs, it is important to have a thorough prior understanding of the functional dynamics of these systems. Here the current performance of ten goat holdings in the northern region of Morocco, classified as either commercial milk producers, commercial cheese producers or non-commercial dairy producers, was recorded, based on the Food and Agricultural Organisation and International Centre for Advanced Mediterranean Agronomic Studies (FAO-CIHEAM) technical and economic indicators, to assess whether intensification of dairy production was financially viable. Fecundity and prolificacy rates were comparatively lower than those achieved by many European Mediterranean herds. Both kid and doe mortality were higher on commercial dairy holdings, where dairy sales provided an additional, rather than alternative, source of income to goat sales. Despite this, due to significantly higher expenditure on supplementary feed, gross margin per doe did not differ significantly between holding types. With the exception of indigenous Greek herds, all European Mediterranean herds outperform those of northern Morocco. The study suggests that a low level of supplementary feeding is constraining goat dairy production in northern Morocco, and that the current high cost and limited availability of additional supplementary feed restricts the financial viability of intensification. Alternative feeding strategies within a participatory approach that might ameliorate these problems, and value chain constraints, are discussed.
Effect of Pollution Controls on Atmospheric PM2.5 Composition during Universiade in Shenzhen, China
Authors: Dewan Nitika , Wang Yu-Qin , Zhang Yuan-Xun , Zhang Yang , He Ling-Yan , Huang Xiao-Feng , Majestic Brian
Published: April 2016

The 16th Universiade, an international multi-sport event, was hosted in Shenzhen, China from 12 to 23 August 2011. During this time, officials instituted the Pearl River Delta action plan in order to enhance the air quality of Shenzhen. To determine the effect of these controls, the current study examined the trace elements, water-soluble ions, and stable lead isotopic ratios in atmospheric particulate matter (PM) collected during the controlled (when the restrictions were in place) and uncontrolled periods. Fine particles (PM2.5) were collected at two sampling sites in Shenzhen: “LG”—a residential building in the Longgang District, with significant point sources around it and “PU”—Peking University Shenzhen Graduate School in the Nanshan District, with no significant point sources. Results from this study showed a significant increase in the concentrations of elements during the uncontrolled periods. For instance, samples at the LG site showed (controlled to uncontrolled periods) concentrations (in ng·m−3) of: Fe (152 to 290), As (3.65 to 8.38), Pb (9.52 to 70.8), and Zn (98.6 to 286). Similarly, samples at the PU site showed elemental concentrations (in ng·m−3) of: Fe (114 to 301), As (0.634 to 8.36), Pb (4.86 to 58.1), and Zn (29.5 to 259). Soluble Fe ranged from 7%–15% for the total measured Fe, indicating an urban source of Fe. Ambient PM2.5 collected at the PU site has an average 206Pb/204Pb ratio of 18.257 and 18.260 during controlled and uncontrolled periods, respectively. The LG site has an average 206Pb/204Pb ratio of 18.183 and 18.030 during controlled and uncontrolled periods, respectively. The 206Pb/204Pb ratios at the PU and the LG sites during the controlled and uncontrolled periods were similar, indicating a common Pb source. To characterize the sources of trace elements, principal component analysis was applied to the elements and ions. Although the relative importance of each component varied, the major sources for both sites were identified as residual oil combustion, secondary inorganic aerosols, sea spray, and combustion. The PM2.5 levels were severely decreased during the controlled period, but it is unclear if this was a result of the controls or change in meteorology.
Droplet-based Biosensing for Lab-on-a-Chip, Open Microfluidics Platforms
Authors: Dak Piyush , Ebrahimi Aida , Swaminathan Vikhram , Duarte-Guevara Carlos , Bashir Rashid , Alam Muhammad
Published: April 2016

Low cost, portable sensors can transform health care by bringing easily available diagnostic devices to low and middle income population, particularly in developing countries. Sample preparation, analyte handling and labeling are primary cost concerns for traditional lab-based diagnostic systems. Lab-on-a-chip (LoC) platforms based on droplet-based microfluidics promise to integrate and automate these complex and expensive laboratory procedures onto a single chip; the cost will be further reduced if label-free biosensors could be integrated onto the LoC platforms. Here, we review some recent developments of label-free, droplet-based biosensors, compatible with “open” digital microfluidic systems. These low-cost droplet-based biosensors overcome some of the fundamental limitations of the classical sensors, enabling timely diagnosis. We identify the key challenges that must be addressed to make these sensors commercially viable and summarize a number of promising research directions.
Sputter-Deposited Indium–Tin Oxide Thin Films for Acetaldehyde Gas Sensing
Authors: Cindemir Umut , Lansåker Pia , Österlund Lars , Niklasson Gunnar , Granqvist Claes-Göran
Published: April 2016

Reactive dual-target DC magnetron sputtering was used to prepare In–Sn oxide thin films with a wide range of compositions. The films were subjected to annealing post-treatment at 400 °C or 500 °C for different periods of time. Compositional and structural characterizations were performed by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, Rutherford backscattering and scanning electron microscopy. Films were investigated for gas sensing at 200 °C by measuring their resistance response upon exposure to acetaldehyde mixed with synthetic air. We found that the relative indium-to-tin content was very important and that measurable sensor responses could be recorded at acetaldehyde concentrations down to 200 ppb, with small resistance drift between repeated exposures, for both crystalline SnO2-like films and for amorphous films consisting of about equal amounts of In and Sn. We also demonstrated that it is not possible to prepare crystalline sensors with intermediate indium-to-tin compositions by sputter deposition and post-annealing up to 500 °C.
Load Concentration Factor Based Analytical Method for Optimal Placement of Multiple Distribution Generators for Loss Minimization and Voltage Profile Improvement
Authors: Shahzad Mohsin , Ahmad Ishtiaq , Gawlik Wolfgang , Palensky Peter
Published: April 2016

This paper presents novel separate methods for finding optimal locations, sizes of multiple distributed generators (DGs) simultaneously and operational power factor in order to minimize power loss and improve the voltage profile in the distribution system. A load concentration factor (LCF) is introduced to select the optimal location(s) for DG placement. Exact loss formula based analytical expressions are derived for calculating the optimal sizes of any number of DGs simultaneously. Since neither optimizing the location nor optimizing the size is done iteratively, like existing methods do, the simulation time is reduced considerably. The exhaustive method is used to find the operational power factor, and it is shown with the results that the losses are further reduced and voltage profile is improved by operating the DGs at operational power factor. Results for power loss reduction and voltage profile improvement in IEEE 37 and 119 node radial distribution systems are presented and compared with the the loss sensitivity factor (LSF) method, improved analytical (IA) and exhaustive load flow method (ELF). The comparison for operational power factor and other power factors is also presented.
Performance of Hybrid Reinforced Concrete Beam Column Joint: A Critical Review
Authors: Kabir Md , Alam M. , Said Aly , Ayad Achraf
Published: April 2016

Large residual strain in reinforced concrete structures after a seismic event is a major concern for structural safety and serviceability. Alternative reinforcement materials like fiber-reinforced polymer (FRP) have been widely used to mitigate corrosion problems associated with steel. Low modulus of elasticity and brittle behavior compared to steel has made the use of FRP unsuitable in seismic resistant strictures. A combination of steel-FRP reinforcement configuration can address the problem of corrosion. Therefore, introducing a material that shows strong post elastic behavior without any decay due to corrosion is in demand. Shape memory alloy (SMA), a novel material, is highly corrosion resistive and shows super elastic property. Coupling SMA with FRP or steel in the plastic hinge region allows the structure to undergo large deformations, but regains its original shape upon unloading. In this study, the performance characteristics of four previously tested beam-column joints reinforced with different configurations (steel, SMA/steel, glass fiber reinforced polymer (GFRP) and SMA/FRP) are compared to assess their capacity to endure extreme loading. Experimental results are scrutinized to compare the behavior of these specimens in terms of load-story drift and energy dissipation capacity. SMA/FRP and SMA/Steel couples have been found to be an acceptable approach to reduce residual deformation in beam-column joints with adequate energy dissipation capacity. However, SMA/FRP is superior to SMA/Steel concerning to the corrosion issue in steel.
Potential of UAVs for Monitoring Mudflat Morphodynamics (Application to the Seine Estuary, France)
Authors: Jaud Marion , Grasso Florent , Le Dantec Nicolas , Verney Romaric , Delacourt Christophe , Ammann Jérôme , Deloffre Julien , Grandjean Philippe
Published: April 2016

Intertidal mudflats play a critical role in estuarine exchange, connecting marine and continental supplies of nutrients and sediments. However, their complex morphodynamics, associated with a wide range of physical and biological processes, are still poorly understood and require further field investigation. In addition, mudflats are challenging areas for Structure-from-Motion (SfM) photogrammetric surveys. Indeed, the mudflats generally hold back residual tidal water, which can make stereo restitution particularly difficult because of poor correlations or sun-glint effects. This study aims to show the potential of light UAVs (Unmanned Aerial Vehicles) for monitoring sedimentary hydrodynamics at different spatial scales in a silty estuary. For each UAV mission an orthophotograph and a Digital Elevation Model (DEM) are computed. From repeated surveys the diachronic evolution of the area can be observed via DEM differencing. Considering the ground texture in such a context, the stereo restitution process is made possible because of the high spatial resolution of the UAV photographs. Providing a synoptic view as well as high spatial resolution (less than 4 cm), the UAV dataset enables multi-scale approaches from the study of large areas to the morphodynamics of smaller-scale sedimentary structures and the morphodynamics impact of plant ground cover.
Induction of ROS Overload by Alantolactone Prompts Oxidative DNA Damage and Apoptosis in Colorectal Cancer Cells
Authors: Ding Yushuang , Wang Hongge , Niu Jiajing , Luo Manyu , Gou Yangmei , Miao Lining , Zou Zhihua , Cheng Ying
Published: April 2016

Cancer cells typically display higher than normal levels of reactive oxygen species (ROS), which may promote cancer development and progression but may also render the cancer cells more vulnerable to further ROS insult. Indeed, many of the current anticancer therapeutics kill cancer cells via induction of oxidative stress, though they target both cancer and normal cells. Recently, alantolactone (ATL), a natural sesquiterpene lactone, has been shown to induce apoptosis by increasing ROS levels specifically in cancer cells; however, the molecular mechanisms linking ROS overproduction to apoptosis remain unclear. Here we show that the ATL-induced ROS overload in human SW480 and SW1116 colorectal cancer cells was followed by a prominent accumulation of cellular oxidized guanine (8-oxoG) and immediate increase in the number of DNA strand breaks, indicating that increased ROS resulted in extensive oxidative DNA damage. Consequently, the G1/S-CDK suppresser CDKN1B (p21) and pro-apoptotic proteins Bax and activated caspase-3 were upregulated, while anti-apoptotic Bcl-2 was downregulated, which were followed by cell cycle arrest at G1 and marked apoptosis in ATL-treated cancer but not non-cancer cells. These results suggest that the ATL-induced ROS overload triggers cell death through induction of massive oxidative DNA damage and subsequent activation of the intrinsic apoptosis pathway.