44 research outputs found

    Comprehensive review of foam application during foam assisted water alternating gas (FAWAG) method

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    © Maxwell Scientific Organization, 2014. In the last few decades, much focus has been placed on enhancing oil recovery from existing fields. This is accomplished by the study and application of various methods. As for recent cases, the Study of fluid mobility control and sweep efficiency in gas injection process as well as Water Alternating Gas (WAG) method have demonstrated positive results on oil recovery and thus gained wide interest in petroleum industry. WAG injection application results in an increased oil recovery. Its mechanism consists in reduction of Gas Oil Ratio (GOR). However, there are some problems associated with this which includes poor volumetric sweep efficiency due to its low density and high mobility when compared with oil. This has led to the introduction of Foam Assisted Water Alternating Gas (FAWAG) technique, which in contrast with WAG injection, acts in improving the sweep efficiency and reducing the gas oil ration therefore maximizing the production rate from the producer wells. This study presents a comprehensive review of FAWAG process from perspective of Snorre field experience. In addition some comparative results between FAWAG and the other EOR methods are presented including their setbacks. The main aim is to provide a solid background for future laboratory research and successful field application-extend

    Evaluation of the Mechanical Properties of Normal Concrete Containing Nano-MgO under Freeze–Thaw Conditions by Evolutionary Intelligence

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    In this research, different amounts of nano-MgO were added to normal concrete samples, and the effect of these particles on the durability of the samples under freeze and thaw conditions was investigated. The compressive and tensile strength as well as the permeability of concrete containing nanoparticles were measured and compared to those of plain samples (without nanoparticles). The age of concrete samples, percentage of nanoparticles, and water-to-binder ratio are the variables of the current research. Based on the results, the addition of 1% nano-MgO to the normal concrete with a water-to-binder ratio of 0.44 can reduce the permeability up to 63% and improve the compressive and tensile strengths by 9.12% and 10.6%, respectively. Gene Expression Programming (GEP) is applied, and three formulations are derived for the prediction of mechanical properties of concrete containing nano-MgO. In this method, 80% of the dataset is used randomly for the training process and 20% is utilized for testing the formulation. The results obtained by GEP showed acceptable accuracy

    Expression of Stem Cell Markers in the Human Fetal Kidney

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    In the human fetal kidney (HFK) self-renewing stem cells residing in the metanephric mesenchyme (MM)/blastema are induced to form all cell types of the nephron till 34th week of gestation. Definition of useful markers is crucial for the identification of HFK stem cells. Because wilms' tumor, a pediatric renal cancer, initiates from retention of renal stem cells, we hypothesized that surface antigens previously up-regulated in microarrays of both HFK and blastema-enriched stem-like wilms' tumor xenografts (NCAM, ACVRIIB, DLK1/PREF, GPR39, FZD7, FZD2, NTRK2) are likely to be relevant markers. Comprehensive profiling of these putative and of additional stem cell markers (CD34, CD133, c-Kit, CD90, CD105, CD24) in mid-gestation HFK was performed using immunostaining and FACS in conjunction with EpCAM, an epithelial surface marker that is absent from the MM and increases along nephron differentiation and hence can be separated into negative, dim or bright fractions. No marker was specifically localized to the MM. Nevertheless, FZD7 and NTRK2 were preferentially localized to the MM and emerging tubules (<10% of HFK cells) and were mostly present within the EpCAMneg and EpCAMdim fractions, indicating putative stem/progenitor markers. In contrast, single markers such as CD24 and CD133 as well as double-positive CD24+CD133+ cells comprise >50% of HFK cells and predominantly co-express EpCAMbright, indicating they are mostly markers of differentiation. Furthermore, localization of NCAM exclusively in the MM and in its nephron progenitor derivatives but also in stroma and the expression pattern of significantly elevated renal stem/progenitor genes Six2, Wt1, Cited1, and Sall1 in NCAM+EpCAM- and to a lesser extent in NCAM+EpCAM+ fractions confirmed regional identity of cells and assisted us in pinpointing the presence of subpopulations that are putative MM-derived progenitor cells (NCAM+EpCAM+FZD7+), MM stem cells (NCAM+EpCAM-FZD7+) or both (NCAM+FZD7+). These results and concepts provide a framework for developing cell selection strategies for human renal cell-based therapies

    Threatened reef corals of the world

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    10.1371/journal.pone.0034459PLoS ONE73

    The value of validated vulnerability data for conservation planning in rapidly changing landscapes

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    Data needed for informed conservation prioritization are generally greater than the data available, and surrogates are often used. Although the need to anticipate threats is recognized, the effectiveness of surrogates for predicting habitat loss (or vulnerability) to land-use change is seldom tested. Here, we compared properties of two different vulnerability surrogates to validated vulnerability—validated prediction of habitat conversion based on a recent assessment of land-use change. We found that neither surrogate was a particularly effective predictor of vulnerability. Importantly, both surrogates performed poorly in places most imminently threatened with habitat conversion. We also show that the majority of areas protected over the last two decades have low vulnerability to the most active threatening process in this biome (habitat conversion). The contrary patterns of vulnerability and protection suggest that use of validated vulnerability would help to clarify protection needs, which might lead to the improvement of conservation decisions. Our study suggests the integration of validated vulnerability into conservation planning tools may be an important requirement for effective conservation planning in rapidly changing landscapes. We apply our results to discuss the practical considerations and potential value of incorporating validated vulnerability into conservation planning tools both generally and in the context of New Zealand’s indigenous grasslands
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