bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling the Impact of Alkaline-Surfactant and Alkaline-Surfactant-Polymer Flooding Processes on Scale Precipitation and Management
Authors: Al Kalbani Munther Mohammed , Jordan Myles Martin , Mackay Eric James , Sorbie Ken Stuart , Nghiem Long X. 
Published: June 2020

Abstract
Mineral scaling issues have been reported in many alkaline and Alkaline-Surfactant-Polymer (ASP) projects. The role of the in situ mineral reactions on the produced scaling ions and pH has been little reported in the literature. The objective of this study is to investigate the impact of the in situ chemical and geochemical interactions on the scale precipitation risk when the fluids reach the wellbore, and their inhibition during Alkaline-Surfactant (AS) and ASP flooding processes.
Reservoir simulation is used to model the geochemical interactions and chemical flood flow behaviour using 2D areal and vertical homogeneous and heterogeneous models. Data from the literature is used to model oil, water and rock interactions (interfacial tension, reaction rate parameters, relative permeability, chemical adsorption and polymer viscosity) for surfactant, and sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) alkalis, and HPAM polymer. At the wellbore, squeeze modelling is used to investigate the volume, concentration and cost of calcite scale inhibitor for three different AS and ASP flooding options.
Results show that the in situ rock dissolution, mineral precipitation and brine mixing reduce the produced ion concentrations (Ca2+, Mg2+, HCO3-) and pH compared to the initial concentration and the injected pH value. The calcite scaling risk can be high during Na2CO3 injection while silica and Mg(OH)2 scales are potential minerals that will precipitate in the production system during NaOH injection. Uncertainty in the mineral reaction rate parameters, especially mineral surface area, is important and must be captured, as this may impact the scaling risk in the producer. Among the studied flooding options, ASP with pre and post polymer slugs shortens the calcite scaling period, reduces the scaling ion concentrations and the produced water rates. This case, then, requires the least number of squeeze treatments, the lowest scale inhibitor volume, and delivers the highest incremental oil recovery.
This paper gives a workflow for assessing the scaling risks for AS and ASP flooding, with crucial role played by reservoir complexity. It is therefore recommended that scaling assessment calculations following our workflow be carried out for specific AS and ASP field cases.
Impact of Relaxation of LSSW Parameters on Scaling Risk
Authors: Al Kalbani Munther , Al Shabibi Hatem , Ishkov Oleg , Silva Duarte , Mackay Eric , Baraka-Lokmane Salima , Pedenaud Pierre 
Published: June 2020

Abstract
Injection of Low Sulphate Seawater (LSSW) instead of untreated Full Sulphate Seawater (FSSW) is widely used to mitigate barium sulphate (BaSO4) scaling risk at production wells. LSSW injection may no longer be required when the barium (Ba2+) concentrations in the produced water drop below a certain threshold. Such a trigger value could be estimated from the BaSO4 precipitation tendency. Relaxation of requirements for the Sulphate Reduction Plant (SRP) can significantly reduce operational costs. This study investigates the impact of several parameters on the timing and degree of relaxation of the output sulphate (SO42-) concentration by the SRP. Finally, the optimal switching strategy is proposed for a field case.
The strategy for switching from LSSW to FSSW, e.g. time and method (direct or gradual increase in the SO42- concentration) were initially investigated using generic 2D areal and vertical models. The sensitivity study included the impact of reservoir heterogeneity and initial Ba2+ and SO42- ion concentrations. Findings were later applied on a full field reservoir simulation model followed by a mineral scale prediction software to investigate the specific switching strategy for a field that has multiple wells and significantly more complex heterogeneity.
Results show that Ba2+ concentrations in the formation brine impact the choice of switching time more than the output SO42- concentration produced by the SRP. The degree of heterogeneity around the producers also has a significant impact on the switching time. Another parameter is the contrast in the permeability between layers; higher contrast allows longer period of co-production of the scaling ions and thus delays the switching time. In the field case, switching to FSSW at early times allows higher consumption of Ba2+ ions due to its in situ precipitation. Ba2+ is no longer a limiting ion, and so a higher degree of deep reservoir precipitation reduces the requirement for prolonged LSSW injection. Another strategy is a gradual relaxation of LSSW output, which allows even earlier build-up of the injected SO42- concentration compared to the direct FSSW switch.
The study investigates the reservoir parameters that impact SO42- relaxation of LSSW injection for a field. Following the proposed workflow, the optimal relaxation strategy can be designed for other field cases.
Experimental Investigation of the Minimum Inhibitor Concentration in Porous Media
Authors: Yang Weipeng , Wang Yanqing , Fu Chenliang , Lu Jun 
Published: June 2020

Abstract
Bottle test and tube-blocking test are two major methods to estimate the minimum inhibitor concentration (MIC) for scale inhibitor applications, such as scale squeeze and continuous injection. However, they may not adequately represent the behaviors of scales and inhibitors in porous media. In this study, coreflood, bottle test and tube-blocking test were conducted, and the measured MIC values were compared to investigate the mechanism leading to the differences.
Bottle tests were conducted to determine the MIC of phosphino polycarboxylic acid (PPCA) by measuring the Ba2+ concentration in solution. Tube-blocking tests were carried out to determine the MIC of PPCA in stainless steel tubing by recording the increase of differential pressure. Finally, coreflood experiments were conducted to evaluate the performance of PPCA in porous media. Pressure changes were monitored along the core plug and were used to determine the location of BaSO4 deposition. Ba2+ concentrations in effluents were measured and compared with the bottle test results to investigate the performance of PPCA in porous media.
Results show that PPCA cannot stop scale deposition in porous media at the MIC determined by bottle tests and tube-blocking tests. Both bottle tests and tube blocking tests suggest an MIC of 6 ppm for PPCA. However, coreflood results show a noticeable increase of pressure in the first section of the core at 6 ppm. Moreover, the Ba2+ concentration in the effluent with 6 ppm PPCA of coreflood is just slightly higher that measured in the coreflood with no PPCA, which means that the MIC determined by bottle test and tube- blocking test cannot mitigate scale deposition in porous media. Sandpacks with higher permeability show higher permeability reduction after the same pore volume of water injection.
This study finds that the MICs determined by commonly used bottle tests and tube-blocking tests are not adequate to mitigate BaSO4 deposition in porous media. The mechanism of BaSO4 deposition and the behavior of inhibitors in porous media need to be further studied.
Iron Carbonate Scale Inhibitor Selection for Low-Permeability, High-Temperature, Low-Pressure, and Low Water-Cut Gas Wells in Chalk Formation
Authors: Al-Ghamdi Tawfik , Chen Ping , Hagen Thomas , Hamam Mohamed , Shakeel Muzzammil 
Published: June 2020

Abstract
Scaling problems were identified in a typical tight carbonate gas reservoir. Selecting an effective iron carbonate scale inhibitor in low-permeability (≤ 1 mD), high-temperature, low-pressure, and low water-cut gas wells of this reservoir type can be challenging. The scale treatment strategy focused on the application of a downhole scale inhibitor squeeze treatment as one of the most effective methods for controlling scale deposition from the reservoir to the wells.
The scaling index from the scale prediction work indicated a moderate to high scaling potential for siderite and calcite. This paper concentrates on the selection of a scale inhibitor to inhibit scale formation of siderite and calcite under downhole conditions. The approach used to select the most appropriate scale inhibitor formulation consisted of a series of laboratory screening tests, such as anaerobic dynamic scale loop tests and static compatibility tests.
Based on the testing results, the performance of the selected scale inhibitor was evaluated under anaerobic dynamic conditions at high temperature and high pressure on a dynamic loop rig. The dynamic loop test results provide a low MIC of 5 ppm for the qualified scale inhibitor. Additionally, a coreflood experiment was conducted to evaluate potential formation damage to the limestone reservoir.
The results indicate that the scale inhibitor brine at the tested concentrations did not cause damage to the core. The regained permeability of the core plug was greater than 90% after scale inhibitor injection under the reservoir conditions. The static compatibility tests were also conducted to evaluate 10% scale inhibitor compatibility with the brine as well as the field condensate to confirm that the selected scale inhibitor was fully compatible with the contacting fluids.
The novelty of laboratory testing for the selected scale inhibitor to inhibit iron carbonate scale formation has led to a field trial, and a scale inhibitor squeeze treatment was performed successfully.
Performance Improvement of Helical Downhole Gas-Oil Separator Using Experimental Approach
Authors: Najafi Sadegh , Hajidavalloo Ebrahim , Ghanbarzadeh Afshin , Gerami Hamed , Alavi Seyed Mohammad 
Published: June 2020

Summary
Growing demand for a subsurface pump application to perform artificial lift in low-pressure wells increases the necessity of a high-efficiency downhole separator to prevent gas entrance in the pump. The purpose of this study is to empirically investigate the efficiency of a helical downhole separator and provide suggestions for improving its performance. To make the results more practical, dimensionless numbers governing the problem were specified using dimensional analysis and the Buckingham theorem, and a laboratory-scale separator was built. Oil and air were selected as the working fluids for this experiment. The results of the experiments showed that the separator performance was divided into three regions: inefficiency region, rapid-growth region, and nongrowth region. To increase the separator efficiency, the separator was modified by blocking the initial holes of the inner tube to provide a region for developing the prerotational effect. The modified separator showed an increase in efficiency as much as 7%. In the third step, the number of holes that were blocked at the entrance region in the first modification were distributed in the rest of the inner tube so that the total hole area remains constant. The separator efficiency, in this case, was significantly increased compared with the previous two cases by as much as twofold. It was found that the inlet design of the separator significantly affects its performance.
Feasibility and validity of the PERF-FIT test battery to assess movement skills, agility and power among children in low- resource settings.
Authors: Smits-Engelsman Bouwien , Bonney Emmanuel , Neto Jorge Lopes Cavalcante , Jelsma Dorothee L 
Published: June 2020

Abstract
Background: Numerous movement skills and physical fitness tests have been developed for children in high-income countries. However, adaptation of these tests to low-resource settings has been slow and norms are still unavailable for children living in low-income communities. The aim of this paper was to describe the development and validation of the Performance and Fitness (PERF-FIT) test battery, a new test to assess motor skill-related physical fitness in children in low-resource settings. Method: The PERF-FIT test was developed in a stepwise manner. This involved defining the relevant domains of the construct of interest and selecting and evaluating test items. The Content Validity Index (CVI) was used to estimate content validity. Following development of the PERF-FIT test, a preliminary study was performed to validate items and to examine the feasibility of implementing the test in a low-resource community. Structural validity was also determined based on data from eighty (n=80) children (aged 7-12 years) using principal component analysis.Results: The CVI for the throw and catch item was 0.86 and 1.00 for the other nine items, leading to a total CVI score of 0.99. The hierarchical sequence of the item series was demonstrated by highly significant (p<0.001) linear trends, confirming the increase in difficulty of subsequent items. Principal component analysis revealed three factors; the first component is represented by locomotor skills that require static and dynamic balance, the second component by throwing and catching items and the third component by agility and power items. These findings suggest that it is feasible to implement the PERF-FIT in low-resource settings. Conclusion: The PERF-FIT test battery is easy to administer and may be suitable for measuring skill-related physical fitness in in low-resource settings. It has excellent content validity and good structural validity. After minor adaptions, further studies should be conducted to establish normative values, evaluate reliability, and document criterion and cross-cultural validity of this test.
Comparative analyses on epidemiological characteristics of dengue fever in Guangdong and Yunnan, China, 2004-2018
Authors: Yue Yujuan , Liu Qiyong , Liu Xiaobo , Wu Haixia 
Published: June 2020

Abstract
Background Guangdong and Yunnan were the two provinces with the toughest dengue epidemic in China. It was to compare epidemiological characteristics of dengue fever there, 2004-2018. Methods Epidemiological method and spatial-temporal analysis were used to explore time-series, spatial and demographic features of dengue fever.Results 93.7% of indigenous cases and 65.9 % of imported cases in mainland China, 2004-2018 occurred in Guangdong and Yunnan. 55,970 and 5,938 indigenous cases occurred in 108 counties of Guangdong and 8 counties of Yunnan, respectively. 1,146 and 3,050 imported cases occurred in 84 counties of Guangdong and 72 counties of Yunnan, respectively. Guangdong and Yunnan had similar seasonal characteristics for dengue fever, and Guangdong had a longer peak period. 85.1% of indigenous cases in Yunnan were located in Ruili City and Jinghong City along the southwestern border. Most dengue cases in Guangdong occurred in the Pearl River Delta region, and especially more than 70.0% of dengue cases in Guangdong occurred in Guangzhou City. 93.9% of imported cases in Guangdong and Yunnan were imported from 9 countries of Southeast Asia. Thailand, Cambodia and Malaysia were the main imported origins in Guangdong. Myanmar and Laos were the main imported origins in Yunnan. There was a strong male predominance among imported cases and an almost equal gender distribution among indigenous cases. Most dengue cases were from individuals in 21-50 years old, accounting for 57.3% and 62.8% of indigenous cases and 83.2% and 62.6% of imported cases in Guangdong and Yunnan, respectively. There were similar major occupations as housework or unemployment, retiree and businessman for indigenous cases, and businessman for imported cases. However, farmers accounted for a larger proportion of dengue cases in Yunnan.Conclusions The findings of epidemiological characteristics and differences of dengue fever in Guangdong and Yunnan are helpful to formulate targeted, strategic plans and implement effective public health prevention measures in China.
Neuroprotective Effects of Magnesium L-threonate in a Hypoxic Zebrafish Model
Authors: Kim Young Sung , Won Young Ju , Lim Byung Gun , Min Too Jae , Kim Yeon-Hwa , Lee Il-Ok 
Published: June 2020

Abstract
Background: Hypoxia inhibits the uptake of glutamate (a major neurotransmitter in the brain closely related to cognitive function) into brain cells, and the initial response of cells to cortical hypoxia depends on glutamate. Previous studies have suggested that magnesium may have protective effects against hypoxic injuries. In particular, magnesium L-threonate (MgT) may increase magnesium ion concentrations in the brain better than MgSO 4 and improve cognitive function.

Methods: We evaluated cell viability under hypoxic conditions in the MgT- and MgSO 4 -treated human SH-SY5Y neurons, in vivo behavior using the T-maze test following hypoxia in MgT-treated zebrafish, activity of brain mitochondrial dehydrogenase by 2,3,5-triphenyltetrazolium chloride (TTC) staining, and protein expression of the excitatory amino acid transporter (EAAT) 4 glutamate transporter by western blotting.

Results : Among the groups treated with hypoxia, cell viability significantly increased when pre-treated with 1 or 10 mM MgT (p = 0.009 and 0.026, respectively). Despite hypoxic insult, MgT-treated zebrafish showed preferences for the red compartment (p= 0.025 for distance and p= 0.007 for frequency of entries), suggesting memory preservation. TTC staining showed reduced cerebral infarction and preserved absorbance in the MgT-treated zebrafish brain after hypoxia (p=0.010 compared to the hypoxia group). In addition, western blot showed upregulation of EAAT4 protein in the MgT treated group.

Conclusions: Pre-treatment with MgT attenuated cell death and cerebral infarction due to hypoxia and protected cognitive function in zebrafish. In addition, MgT appeared to modulate expression of the glutamate transporter, EAAT4.
Genetic polymorphism of Plasmodium falciparum circumsporozoite protein (PfCSP) on Bioko Island, Equatorial Guinea and global comparative analysis
Authors: Huang Hui-Ying , Liang Xue-Yan , Lin Li-Yun , Chen Jiang-Tao , Ehapo Carlos Salas , Eyi Urbano Monsuy , Li Jian , Jiang Ting-Ting , Zheng Yu-Zhong , Zha Guang-Cai , Xie Dong-De , He Jin-Quan , Chen Wei-Zhong , Liu Xiang-Zhi , Mo Huan-Tong , Chen Xin-Yao , Lin Min 
Published: June 2020

Abstract
Background Plasmodium falciparum circumsporozoite protein (PfCSP) is a potential malaria vaccine candidate, but various genetic polymorphisms of PfCSP among global P. falciparum population become the major barrier to the effectiveness of vaccines. This study aimed to investigate the genetic polymorphisms and natural selection of PfCSP in Bioko and the comparison among global P. falciparum population.Methods From January 2011 to December 2018, 148 blood samples were collected from P. falciparum infected Bioko patients and 96 monoclonal sequences of them were successfully acquired and analyzed with 2200 global PfCSP sequences mined from MalariaGEN Pf3k Database and NCBI. Results In Bioko, the N-terminus of PfCSP showed limited genetic variations and the numbers of repetitive sequences (NANP/NVDP) were mainly found as 40 (35%) and 41 (34%) in central region. Most polymorphic characters were found in Th2R/Th3R region, where natural selection (p>0.05) and recombination occurred. The overall pattern of Bioko PfCSP gene had no obvious deviation from African mainland PfCSP (Fst=0.00878, p<0.05). The comparative analysis of Bioko and global PfCSP displayed the various mutation patterns and obvious geographic differentiation among populations from four continents (p<0.05). The global PfCSP C-terminal sequences were clustered into 138 different haplotypes (H_1 to H_138). Only 3.35% of sequences matched 3D7 strain haplotype (H_1). Conclusions The genetic polymorphism phenomena of PfCSP were found universal in Bioko and global isolates and the majority mutations located at T cell epitopes. Global genetic polymorphism and geographical characteristics were recommended to be considered for future improvement of malaria vaccine design.
"Knock Knock": A qualitative study exploring the experience of household contacts on home visits and their attitude towards people living with TB in South Africa
Authors: Sathar Farzana , Velen Kavindhran , Peterson Meaghan , Charalambous Salome , Chetty-Makkan Candice M 
Published: June 2020

Abstract
Background: Household contract tracing (HHCT) is an important strategy for active tuberculosis case finding and offers an opportunity for testing of other diseases such as HIV. However, there is limited data on the patient-centered approach to HHCT. Our study aimed to describe experiences and preferences of household contacts (HHCs) for HHCT.Methods: We conducted a qualitative study in Rustenburg, South Africa from September 2013 to March 2015. Twenty-four HHCs (≥18 years) had audio-recorded in-depth interviews. We used an inductive thematic analysis approach to develop themes. We made an a priori assumption that we would reach saturation with at least 20 interviews. Results: There were 16 (66.7%) females (median age = 36 years) and eight (33.3%) males (median age = 34 years). Two themes developed: (i) Positive attitude of HHCs towards TB services provided at home and (ii) HHCs relationship to and acceptance of people living with TB (PLTB). The first main theme emphasized that HHCs appreciated the home visits. Participants preferred home visits because they had negative experiences at the clinic such as delayed waiting times and long queues. HHCs supported the screening of children for TB at home. Participants suggested that the research staff could expand their services by screening for diabetes and hypertension alongside TB screening. In the second main theme, there was a sense of responsibility from the HHCs towards accepting the diagnosis of PLTB and caring for them. A sub-theme that emerged was that as their knowledge on TB disease improved, they accepted the TB status of the PLTB empowering them to take care of the PLTB.Conclusions: HHCs are supportive of HHCT and felt empowered by receiving TB education that ultimately allowed them to better understand and care for PLTB. HHCs were supportive of screening children for TB at home. Future HHCT activities should consider raising community awareness on the benefits of TB contact tracing at households.