Polymer Retention during Flow of Polymer Solutions through Porous Media

Polymer solution flow and retention through porous media is of interest to many applications in the oil industry such as drilling, water shut-off and enhanced oil recovery. Operators of mature oil and gas fields are faced with the problem of excessive water production (EWP), which can cause a premature abandonment of some oil and gas wells. It has been found that the injection of high molecular weight polymer solutions through the pay zones of the oil and gas wells would induce a sharp decrease of the water production without affecting the oil and gas production. This effect is called disproportionate permeability reduction (DPR) and the polymer solutions inducing such an effect are called relative permeability modifiers (RPM). Hence, the DPR effect has been utilized in the water shut-off or conformance control of oil and gas wells suffering from EWP. In spite of the extensive research of the DPR effect, there is still a lack of agreement on the mechanisms controlling such an effect and relatively high percentage failures are observed during conformance control field applications. Polymer retention in porous media has been attributed to mechanisms such as bridging-adsorption, adsorption-entanglement, and flow-induced adsorption. These mechanisms have been proposed to account for the increase in flow resistance during or after the flow of polymer solutions through porous media. The DPR effect has been attributed to effects induced by this retained polymer such as steric and lubrication effects, wettability change, segregated oil and water pathways, and swelling and shrinking of the adsorbed polymer layer. The aim of this study is to add knowledge on the effect of polymer solution flow on polymer retention in porous media. In this study, the rheology of high molecular weight polymer solutions was studied using a cone-and-plate setup. Moreover, the characteristics and the effective hydrodynamic thickness of adsorbed polymer layers on glass from these polymer solutions under static conditions were investigated using atomic force microscopy (AFM). Also, quartz crystal microbalance with the dissipation monitoring (QCM-D) was used to investigate the effect of increasing the flow rate of polymer solutions on the adsorbed amount on silica and gold surfaces. Additionally, the mobility reduction and the residual resistance as a result of polymer solution flow through single glass capillaries, 2D and 3D models of porous media were studied. The implementation of the above techniques was used to relate the microscopic effect of the flow of the polymer solutions to the polymer retention in the porous media. The anti-thixotropic behaviour of the polymer solutions, which can be attributed to the shearinduced formation of micron-size transient entanglement networks (TEN), is expected to play a major role in the polymer retention in porous media. These microscopic structures can adsorb on the solid surfaces if the adsorption energy of the polymer/solid system is sufficient. Also, in porous media in which mechanical entrapment is possible, these structures can be entrapped in the small pores and pore throats. Two new mechanisms for polymer retention are proposed in this study: transient-entanglement networks adsorption (TENA) and transient-entanglement networks entrapment (TENE). The TENA is the retention mechanism of the TEN structures in flow systems in which mechanical entrapment is not possible provided that the adsorption energy is sufficient. If mechanical entrapment is possible, then the retention by adsorption and mechanical entrapment are lumped in the TENE mechanism. The results from this study have given a new insight on the flow and retention of polymer solutions through porous media. Hence, it is believed that the improved understanding will improve the design of high molecula

Factors influencing secondary school students' decisions to enter higher education : implications for higher education capacity in the Sultanate of Oman

The major goal of this study is to investigate the factors influencing Omani secondary school students' decisions to enter higher education, and the implications of such decisions for higher education provision.A number of economic, sociological, psychological, demographic and institutional variables, derived from previous literature and from analysis of labour market conditions in Oman, were incorporated in the conceptual framework guiding the research.A questionnaire, developed to suit the Omani context, was distributed to cluster samples of final-year public secondary school students, stratified by gender and specialisation, in 6 educational regions (N= 1950, valid returns= 1830). These were followed by semi-structured interviews with 42 volunteer students and telephone interviews with 4 decision-makers in the Ministry of Education, to discuss emergent issues. Government and non-government documents and statistics on higher education capacity and labour market demand were analysed.Of the factors, Human Capital Theory appears to be the most influential factor on students' decisions. Students' self confidence in their ability, parents' and family influence, and students' own attitudes and perception towards higher education followed. External factors of the labour market and school were considered less influential and friends least. Moreover, students' specific motivation was shaped and largely determined by the characteristics of the Omani work environment. Mediating effects of gender, specialisation and region were discovered.Current capacity of higher education does not meet either students' aspirations or the labour market demand. However, inequities in capacity, combined with the traditional Omani disdain for certain types of work, complicate the issue. Resolving the problem, therefore, requires not only expansion of higher education capacity, but also adjustment and redirection of demand. Additionally, adjusting educational demand will necessitate addressing disparities in salaries and employment conditions between the public and private sectors.Theoretical and policy implications are highlighted and specific recommendations address the latter

Myocardial ischemia reperfusion injury: Apoptotic, inflammatory and oxidative stress role of galectin-3

Background/aims: Myocardial reperfusion has the potential to salvage the ischemic myocardium after a period of coronary occlusion. Reperfusion, however, can cause a wide spectrum of deleterious effects. Galectin-3 (GAL-3), a beta galactoside binding lectin, is closely associated with myocardial infarction (MI), myocardial fibrosis and heart failure. In our study, we investigated its role in ischemia-reperfusion injuries (IR) as this phenomenon is extremely relevant to the early intervention after acute MI.Methods: C57B6/J wild type (WT) mice and GAL-3 knockout (KO) mice were used for murine model of IR injury in the heart where a period of 30 minutes ischemia was followed by 24 hours of reperfusion. Heart samples were processed for immunohistochemical and immunofluorescent labeling, morphometric analysis, western blot and enzyme-linked immunosorbent assay to identify the apoptotic, inflammatory and oxidative stress role of GAL-3.Results: Our results show that there was a significant increase in GAL-3 levels in the heart which shows GAL-3 is playing a role in the ischemia reperfusion injury. Troponin I was also significantly higher in GAL-3-KO group than wild type. Our study shows that GAL-3 is associated with an increase in the antioxidant activity in the IR injured myocardium. Antioxidant enzymes superoxide dismutase, glutathione and catalase were found to be significantly raised in the GAL-3 wild type IR as compared to the GAL-3 KO IR group. A significant increase in apoptotic activity is seen in GAL-3 KO IR group as compared with GAL-3 wild IR group.Conclusion: Our study shows that GAL-3 can affect the redox pathways, controlling cell survival and death, and plays a protective role on the myocardium following IR injury

Galectin-1 in early acute myocardial infarction

Myocardial infarction (MI) is the most serious manifestation of coronary artery disease and the cause of significant mortality and morbidity worldwide. Galectin-1(GAL-1), a divalent 14.5-kDa protein, is present both inside and outside cells, and has both intracellular and extracellular functions. Hypoxia inducible factor-1 alpha (HIF-1α) is a transcription factor mediating early and late responses to myocardial ischemia. Identification of the pattern of expression of GAL-1 and HIF-1α in the heart during the first 24 hours following acute MI will help in understanding early molecular changes in this event and may provide methods to overcome serious complications. Mouse model of MI was used and heart samples were processed for immunohistochemical and immunofluorescent labeling and Enzyme linked immunosorbent assay to identify GAL-1 and HIF 1α levels in the heart during the first 24 hours following MI. There was significant increase in left ventricular GAL-1 at 20 (p = 0.001) and 30 minutes (p = 0.004) following MI. There was also a significant increase in plasma GAL-1 at 4 hours (p = 0.012) and 24 hours (p = 0.001) following MI. A significant increase in left ventricular HIF-1 α was seen at 20 minutes (p = 0.047) following MI. In conclusion, we show for the first time that GAL-1 level in the left ventricle is increased in early ischemic period. We also report for the first time that HIF-1 α is significantly increased at 20 minutes following MI. In addition we report for the first time that mouse plasma GAL-1 level is significantly raised as early as 4 hours following MI

Galectin-1: A biomarker of surgical stress in murine model of cardiac surgery

Galectin-1 (GAL-1) belongs to the family of β-galactoside-binding lectins. It regulates cell-cell and cell-matrix interactions, the immune response, apoptosis, cell cycle, RNA splicing and neoplastic transformation. We investigate the effect of heart manipulation secondary to cardiac surgery on the level of GAL-1 in murine heart and plasma. Male C57B6/J mice were used for adopted model of cardiac surgery. Heart samples were processed for immunohistochemical and immunofluorescent labeling, Enzyme linked immunosorbent assay and quantitative RT-PCR to identify GAL-1 levels in the heart and plasma during the first 24 hours following cardiac surgery. There is significant increase of GAL-1 in the LV at 30 minutes (

Loss of dystrophin staining in cardiomyocytes: A novel method for detection early myocardial infarction

Myocardial infarction (MI) is the most frequent diagnosis made in majority of sudden death cases subjected to clinical and medicolegal autopsies. When sudden death occurs at a very early stage of MI, traditional macroscopic examination, or histological stains cannot easily detect the myocardial changes. For this reason we propose a new method for detecting MI at an early stage. Murine model of MI was used to induce MI through permanent ligation of left anterior descending branch of left coronary artery. Five groups of C57B6/J mice were used for inducing MI, which includes 20 minutes, 30 minutes, one hour, four hours and 24 hours post MI groups. One naïve group and sham-operated groups were used as controls. There is loss of dystrophin membranous staining in cardiac myocytes occurs as early as 20 minutes post myocardial infarction. This can be used as a novel method to diagnose early myocardial infarction in post mortem cases where diagnosis is unclear. In conclusion, evaluation of immunohistochemical expression of dystrophin represents a highly sensitive method for detecting early myocardial infarction due to the loss of staining in the infarcted areas. Dystrophin immunostaining can also be used to assess myocardial architecture

Acute myocardial infarction and myocardial ischemia-reperfusion injury: A comparison

Myocardial infarction (MI) denotes the death of cardiac myocytes due to extended ischemia. Myocardial reperfusion is the restoration of coronary blood flow after a period of coronary occlusion. Reperfusion has the potential to salvage ischemic myocardium but paradoxically can cause injury, a phenomenon called as \u27reperfusion injury\u27 (IR). Standard histologic, immunohistochemical and Elisa techniques were used to study the histopathologic, oxidative, apoptotic and inflammatory changes in MI and IR. The IL-6 levels in the LV of the MI group were significantly raised as compared to the IR group (P=0.0008). Plasma IL-6 was also significantly increased in the MI group as compared to the IR group (P=0.031). MI model was also associated with increase in the neutrophil polymorphs number in the infarction related myocardium as compared to the re-perfused myocardium. A significant increase in troponin I level in the MI group as compared to the IR group is also seen (P=0.0001). Our IR model showed enhanced pro-apoptotic mediators like cleaved caspase-3 (P=0.005) and cytochrome c in the myocardium as compared to the MI model. In conclusion, myocardial damage in MI is mainly due to ischemic necrosis and inflammatory mechanisms while apoptosis is the main mechanism of cell death in IR in addition to limited ischemic necrosis

Waqf as a Financing Tool and Its Role in Achieving SDGs and Foreseeing the Future

The significance of Waqf goes beyond being an act of worship that has been ordained to fulfill society’s welfare in many fronts, spiritual and material, individual and social, as well as here and hereafter. It is characterized as being one of the most pertinent tools of Islamic economics. This is due to its autonomy, flexibility, sustainability, and continuity, and its ability to achieve socioeconomic development for contemporary and future generations alike. The Waqf system have witnessed various stages of development in the light of the Islamic civilization to encompass all socioeconomic sectors; education, culture, healthcare, housing, services, politics, military, energy, infrastructure, food and water security, clean and affordable energy, and more. Proving itself to be capable of achieving high and advanced potentials of Sustainable Development Goals (SDGs). This chapter aims at investigating the capacity and flexibility of Waqf, and its ability to achieve advanced progress towards various SDGs. The challenges facing Waqf and hindering it from achieving its great potentials are analyzed and solutions and policy recommendations would be presented

Convergent Validity and Internal Consistency of an Arabic Snaith Hamilton Pleasure Scale

Anhedonia, a reduced capacity for pleasure, is viewed as a trait-like vulnerability marker for schizophrenia and depressive disorders. To date there are scarce data from the Arab world on anhedonia as a symptom, and even less on the psychometric properties of instruments designed to assess it. This study examines the internal consistency of an Arabic version of the Snaith Hamilton Pleasure Scale (SHAPS), and its convergence with real-time hedonic responses to emotional stimuli. A correlational study design is used; undergraduate students ( N = 113) in the United Arab Emirates (UAE) completed the SHAPS, and also undertook an expanded version of the picture rating task (PRT). The PRT required participants to rate a series of pleasant and unpleasant images in terms of emotional valence. Levels of anhedonia as assessed by SHAPs were similar to those observed in nonclinical populations in other countries. Internal consistency for the Arabic version of SHAPs was very good; α = .86. Furthermore, SHAPS scores were correlated with lower valence ratings for pleasant images ( r = .36), and uncorrelated with unpleasant images. The SHAPS appears to be a useful instrument for assessing anhedonia in the present UAE student population