bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbiological Safety of Fruit Juices Consumed in Cafes and Restaurants of Debre-Markos Town, North Western Ethiopia
Authors: Geta Kindu , Kebede Ameha , Chemedissa Meseret
Published: June 2018

Improperly prepared fresh fruit and vegetable juices are recognized as an emerging cause of food borne illnesses. Therefore, this study was aimed at evaluating the microbiological safety of fresh fruit juices marketed in Debre-Markos town and their hygienic conditions of preparations. Thirty six fruit juices samples were collected from 6 cafés and restaurants of Debre-Markos town and analyzed for total aerobic viable bacterial count (TAVBC), total staphylococcal count (TSC), aerobic spore forming bacterial count (ASFBC), total coliform count (TCC), fecal coliform count (FCC), yeast and mould count (YMC). The spread plate method was used for the isolation of microorganisms on appropriate selective media. All isolates were characterized following standard methods. Bacterial and fungal species were isolated following standard methods. Questionnaires were distributed for 30 juice makers to obtain preliminary information on hygienic and safety practices of fruit juice makers. Results show that the mean TAVBC, ASFBC, TSC, yeast and mold, TCC and FCC of mango were 2.2±0.48x106,0.13±0.04x105 ,0.004x105 ,1.1±0.2x106 ,0.15±0.05x105,5.7±3.73x104 and 0.06±0.04x104 cfu/ml respectively. The mean of TAVBC, ASFBC, TSC, YMC, TCC, and FCC of avocado juice were 3.6±0.6x106, 0.08±0.02x105, 0.27±0.07x105, 1.2±0.4x106, 0.02±0.01x105, 6.46±3.7x104, and 0.2±0.1x104 cfu/ml respectively. The bacterial isolates were identified as Staphylococcus aureus, Escherichia coli, Klebsiella spp. Bacillus cereus, Enterobacter spp., Enterococcous spp., Streptococcus spp., and Serratia spp. while the identities of the fungal isolates were Fusarium spp., Mucor spp. and Saccharomyces cerevisiae. The results also showed that the microbial loads of most of the fruit juices were higher than the specifications set for fruit juices sold in the Gulf region and other parts of the world. Most venders obtained fruit from the open market and all juice makers lacked special training in food hygiene and safety. Therefore, regular training and health education on food hygiene and safety is recommended for juice handlers to improve the quality of fresh fruit juices in the study area.
Atmospheric Pollution Monitoring by Water Rain Analysis
Authors: Muro Jr Aldo , Lo Presti Diego , Antoniosi Filho Nelson Roberto , Viégas Wendt Elieser , Pittet Muro Nicola
Published: June 2018

Environmental legislation is moving towards global standards for ease of application and to impose sanctions and penalties when necessary, without compromising human health and biota. International environmental measures for control and monitoring of atmospheric air only monitor emissions of SOx, NOx, O3, and Pb. In general, most research work in air pollution done using the analysis of elements in rainwater show analysis of trace metals such as Na, Mg, Zn, and Mn. In this work, trace metals in the rainwater at the city of Goiânia, capital of the State of Goiás, were analyzed. Goiânia is a large city set in a predominantly agricultural province located in central Brazil. Presence of trace metals in rainwater was detected, indicating atmospheric air pollution levels higher than occupational limits set by WHO.
Functionalized Folic Acid-Chitosan Nanoparticles for Encapsulation of Dietary Polyphenols
Authors: Chanphai P. , Tajmir-Riahi H.A.
Published: June 2018

Encapsulation of antioxidant polyphenols leads to increase solubility and bioavailability of these micronutrients in solution. The encapsulation of antioxidant resveratrol, genistein and curcumin by folic acid-chitosan nanocapsules was studied in aqueous solution, using multiple spectroscopic methods, TEM images. Structural analysis showed that polyphenol bindings are via hydrophilic, hydrophobic and H-bonding contacts with resveratrol forming more stable conjugates. As chitosan size increased, the binding efficacy and stability of polyphenol-polymer adducts were increased. Polyphenol binding induced major alterations of chitosan morphology. Chitosan nanoparticles are capable of delivery of polyphenols in vitro.
Acute Administration of Caffeine: The Effect on Motor Coordination, Higher Brain Cognitive Functions and the Social Behavior of BLC57 Mice
Authors: Almosawi Sayed , Baksh Hasan , Qareeballah Abdulrahman , Falamarzi Faisal , Alsaleh Bano , Alrabaani Malak , Aljalban Ali , Mahdi Sadiq , Kamal Amer
Published: June 2018

Heavy caffeine consumption is associated with adverse health effects. The effects of moderate and high doses of caffeine mixed with drinking water on the motor coordination, learning and memory and the social behavior in mice were studied in mice. Animals were divided into 3 groups: control group, moderate dose group (Ac MD) and high dose group (Ac HD). The animals were tested after 7 days of caffeine administration. Rota rod test for motor coordination showed that the mice of the moderate dose group could stay more time on the rotating rod before they fall than the control group and the high dose group. Water maze test for learning and memory showed better performance of mice receiving moderate dose of caffeine compared to the other groups. Animals that were administered moderate as well as high doses of caffeine showed no sociability and no preference for social novelty in the three-chamber test used to test the social behavior. In elevated plus maze, control animals showed no anxiety- like behavior while mice administered with caffeine were both showing anxiety-like behaviors. We concluded that acute administration of moderate dose of caffeine to mice could enhance their spatial memory and motor coordination. High doses however caused defects in memory and learning. The social behavior as the level of anxiety and sociability was affected negatively by moderate as well as high dose caffeine administration.
Artificial Membrane Induced by Novel Biodegradable Nanofibrous Scaffold in the Masquelet Procedure for the Treatment of Segmental Bone Defects
Authors: Yu Yi-Hsun , Wu Ren-Chin , Lee Demei , Chen Che-Kang , Liu Shih-Jung
Published: June 2018

Masquelet induced-membrane technique for the treatment of segmental bone defects includes a two-stage surgical procedure, and polymethylmethacrylate (PMMA) plays a major role in the treatment. However, the PMMA spacer must be surgically removed. Here, we investigated the potential of poly (lactic-co-glycolic acid) (PLGA) nanofibers, a biodegradable material to replace PMMA spacer, allowing the bioactive membrane to be induced, and the spacer to degrade without the additional surgery on a rabbit femoral segmental bone defect model. PLGA nanofibers were shown to degrade completely six weeks after implantation in the investigated animals, and a thick membrane was found to circumferentially fold around the segmental bone defects. Results from image studies demonstrated that, in the group without bone graft, all studied femurs exhibited either nonunion or considerable malunion. In contrast, the femurs in the bone graft group had a high union rate without considerable deformities. Histological examinations suggested that the membranous tissue in this group was rich in small blood vessels and the expression of BMP2 and VEGF increased. Our results demonstrate that the biodegradable PLGA nanofibers may be useful for replacing the PMMA spacer as the bioactive-membrane inducer, facilitating the process of healing and removing the need for repeated surgeries.
Exergy Inefficiency: An Indicator for Sustainable Development Analysis
Authors: Lucia Umberto , Grisolia Giulia
Published: June 2018

The present days can be considered a crossroad in the history our word because the economic, social and ecological needs don't agree one another. The result is a continuous growth of poverty and an increase of the ecological degradation. This has generated the present difficult socio-economic state, and it seems very difficult to escape. A new viewpoint must be introduced, but it cannot based on the usual economic indicators. So, new indicators must be introduced. They must allow us to consider the technological level, the environmental impact and the socio-economic conditions. In this paper we suggest three indicators based on an engineering approach of irreversibility. Three applications are shown in order to highlight the possible interest from different scientists and researchers in engineering, economy, etc, in order to develop sustainable approaches and policies for decision makers.
Neuropsychiatric Borreliosis/Tick-Borne Disease: An Overview
Authors: Bransfield Robert C
Published: June 2018

There is increasing evidence and recognition that Lyme borreliosis, and other associated tick-borne diseases (LB/TBD) cause mental symptoms. Data was drawn from databases, search engines and clinical experience to review current information on LB/TBD. LB/TBD infections cause immune and metabolic effects that result in a gradually developing spectrum of neuropsychiatric symptoms, usually presenting with significant comorbidity and may include developmental disorders, autism spectrum disorders, schizoaffective disorders, bipolar disorder, depression, anxiety disorders (panic disorder, social anxiety disorder, generalized anxiety disorder, posttraumatic stress disorder, intrusive symptoms), eating disorders, decreased libido, sleep disorders, addiction, opioid addiction, cognitive impairments, dementia, seizure disorders, suicide, violence, anhedonia, depersonalization, dissociative episodes, derealization and other impairments. Screening assessment followed by a comprehensive psychiatric clinical exam relevant to patient’s complaints and findings with a thorough history, mental status exam, review of systems, neurological exam, physical exam, a knowledgeable interpretation of laboratory findings, pattern recognition and clinical judgment facilitate diagnosis. Psychotropics and antibiotics may help improve functioning and prevent further disease progression. Awareness of the association between LB/TBD and neuropsychiatric impairments and studies of their prevalence in neuropsychiatric conditions can improve understanding of the causes of mental illness and violence and result in more effective prevention, diagnosis and treatment.
Umbral Methods and Harmonic Numbers
Authors: Dattoli Giuseppe , Germano Bruna , Licciardi Silvia , Martinelli Maria Renata
Published: June 2018

The theory of harmonic based function is discussed here within the framework of umbral operational methods. We derive a number of results based on elementary notions relying on the properties of Gaussian integrals.
On the Multiplicative Degree-Based Topological Indices of Silicon-Carbon Si2C3-I[p,q] and Si2C3-II[p,q]
Authors: Kwun Young Chel , Virk Abaid ur Rehman , Nazeer Waqas , Kang Shin Min
Published: June 2018

The application of graph theory in chemical and molecular structure research far exceeds people's expectations, and it has recently grown exponentially. In the molecular graph, atoms are represented by vertices and bonded by edges. Closed forms of multiplicative degree-based topological indices which are numerical parameters of the structure and determine physico-chemical properties of the concerned molecular compound. In this article, we compute and analyze many multiplicative degree-based topological indices of silicon-carbon Si2C3-I[p,q] and Si2C3-II[p,q].
Wastewater Remediation Using Microbial Fuel Cells and Bioenergy Production
Authors: Prasath Balaji B. , Poon Karen
Published: June 2018

Microbial Fuel Cells (MFCs) representing a promising technology for the extract of energy and resources through wastewater and it also offer an economic solution to the problem of environment effluent and energy crisis in near future. The advance device is rather appealing, due its potential benefits, its practical application is, however hindered by several drawbacks, such an internally competing microbial reaction, and low power generation. This report is an endeavor to address various design connected to the MFCs application to wastewater treatment, in particular cost effective bioelectricity from waste water are reviewed and discussed with a multidisciplinary approach. The conclusions drawn herein can be of practical interest to all new researchers dealing with effluent wastewater treatment using MFCs.
Structure-Function Changes of the Distal Outflow Tract in Response to Nitric Oxide
Authors: Susannah Waxman Susannah , Wang Chao , Dang Yalong , Hong Ying , esfandiari hamed , Shah Priyal , Lathrop Kira L. , Loewen Ralitsa , Loewen Nils A.
Published: June 2018

Purpose: To correlate outflow function and outflow tract vessel diameter changes induced by nitric oxide (NO). Methods: In a porcine anterior segment perfusion model, the effects of a nitric oxide donor (100 µM DETA-NO) on outflow facility were compared to controls (n=8 per group) with trabecular meshwork (TM) and after circumferential ab interno trabeculectomy (AIT). Outflow structures were assessed with spectral domain optical coherence tomography (SD-OCT) before and after NO, or an NO synthase inhibitor (100 µM L-NAME) and the vasoconstrictor, endothelin-1 (100 pg/mL ET-1). Scans were processed with a custom macro script and aligned for automated reslicing and quantification of cross-sectional outflow tract areas (CSA). Results: The facility increased after DETA-NO (0.189±0.081 μL/min·mmHg, p=0.034) and AIT (0.251±0.094 μL/min·mmHg, p=0.009), respectively. Even after AIT, DETA-NO increased the facility by 61.5% (0.190±0.074 μL/min·mmHg, p=0.023) and CSA by 13.9% (p<0.001). L-NAME + ET-1 decreased CSA by -8.6% (p<0.001). NO increased the diameter of focal constrictions 5.0±3.8 fold. Conclusions: NO can dilate vessels of the distal outflow tract and increase outflow facility in a TM-independent fashion. There are short, focally constricting vessel sections that display large diameter changes and may have a substantial impact on outflow.
Early Developmental Exposure to General Anesthetic Agents in Primary Neuron Culture Disrupts Synapse Formation via Actions on the mTOR Pathway
Authors: Xu Jing , Mathena R. Paige , Xu Michael , Wang YuChia , Chang CheJui , Fang Yiwen , Zhang Pengbo , Johns Roger A. , Mintz C. David
Published: June 2018

Human epidemiologic studies and laboratory investigations in animal models suggest that exposure to general anesthetic agents (GAs) have harmful effects on brain development. The mechanism underlying this putative iatrogenic condition is not clear and there are currently no accepted strategies for prophylaxis or treatment. Recent evidence suggests that anesthetics might cause persistent deficits in synaptogenesis by disrupting key events in neurodevelopment. Using an in vitro model consisting of dissociated primary cultured mouse neurons we demonstrate abnormal pre- and post-synaptic marker expression after a clinically relevant isoflurane anesthesia exposure conducted during neuron development. We find that pharmacologic inhibition of the mechanistic target of rapamycin (mTOR) pathway can reverse the observed changes. Isoflurane exposure increases expression of phospho-S6, a marker of mTOR pathway activity, in a concentration-dependent fashion and this effect occurs throughout neuronal development. The mTOR 1 complex (mTORC1) and the mTOR 2 complex (mTORC2) branches of the pathway are both activated by isoflurane exposure and this is reversible with branch-specific inhibitors. Upregulation of mTOR is also seen with sevoflurane and propofol exposure, suggesting that this mechanism of developmental anesthetic neurotoxicity may occur with all the commonly used GAs in pediatric practice. We conclude that GAs disrupt the development of neurons during development by activating a well-defined neurodevelopmental disease pathway and that this phenotype can be reversed by pharmacologic inhibition.
Heated Intraperitoneal Chemotherapy in the Management of Ovarian Cancer
Authors: Jewell Andrea , McMahon Megan , Khabele Dineo
Published: June 2018

Heated intraperitoneal chemotherapy (HIPEC) has several potential benefits. Higher doses of chemotherapy can be used with HIPEC because the plasma-peritoneal barrier results in little absorption into the blood stream. HIPEC offers higher peritoneal penetration in comparison to an intravenous (IV) regimen and does not have the traditional normothermic intraperitoneal (IP) regimen limitation of post-operative adhesions. Hyperthermia itself has cytotoxic effects and can potentiate antineoplastic effects of chemotherapy in part by increasing the depth of tumor penetration by up to 3 mm. For the treatment of ovarian cancer, HIPEC has been evaluated in the recurrent setting with secondary cytoreduction. Recent studies, including a prospective trial, have evaluated its role in primary management of ovarian cancer. This review summarizes previous and ongoing studies regarding the use of HIPEC in the management of ovarian cancer.
Cavitation Erosion Resistance and Wear Mechanism Model of Flame-Sprayed Al2O3–40%TiO2/NiMoAl Cermet Coatings
Authors: Szala Mirosław , Hejwowski Tadeusz
Published: June 2018

This manuscript deals with the cavitation erosion resistance of low-velocity oxy-flame (LVOF) sprayed Al2O3–40%TiO2/NiMoAl cermet coatings, a new functional application of cermet coatings. The aim of the study was to investigate the cavitation erosion mechanism and determine the effect of feedstock powder ratio (Al2O3–TiO2/NiMoAl) of LOVF cermet coatings on their cavitation erosion resistance. As-sprayed coatings were investigated for roughness, porosity, hardness, Young’s modulus. Microstructural characteristics of the cross-section and the surface of as-sprayed coatings were examined by light optical microscopy (LOM) and scanning electron microscopy (SEM) equipped with the EDS and XRD methods. Coatings cavitation tests were conducted in accordance with the ASTM G32 standard with usage of reference samples made from steel, copper and aluminum alloys. Cavitation erosion resistance was measured by weight and volume loss, and normalised cavitation erosion resistance was calculated. Surface eroded due to cavitation was examined in successive time intervals by LOM and SEM-EDS. On the basis of coating properties and cavitation investigations, a phenomenological model of the cavitation erosion of Al2O3–40%TiO2/NiMoAl cermet coatings was elaborated. General relationships between their properties, microstructure and cavitation wear resistance were established. The Al2O3–40%TiO2/NiAlMo composite coating containing 80% of ceramic powder has a higher cavitation erosion resistance than the reference aluminium alloy.
APLICACIÓN MÓVIL PARA LA RECOMENDACIÓN DE ASIGNATURAS EN LOS ESTUDIOS DE GRADO UNIVERSITARIO
Authors: Zafra A. , Gibaja E. , Gámez J. C. , Soto J. M. , Arauzo A. , Moyano J. M. , Ramírez A. , Martínez M.
Published: June 2018

Los Grados Universitarios en sus planes de estudios tienen asignados una serie de créditos optativos, en los que el estudiante tiene libertad para elegir las asignaturas que más le interesen. Esta elección suele ser bastante complicada para los estudiantes, que si bien cuentan con una guía docente de cada asignatura, que les permite conocer los contenidos teóricos y prácticos, los profesores que la imparten, la metodología y los criterios de evaluación, no suele ser suficiente para decidirse. En este contexto, los estudiantes están interesados en las valoraciones que le pueden ofrecer otros compañeros o compañeras que las cursaron, siendo una práctica habitual que los estudiantes recurran a los estudiantes de otros cursos para que les orienten en el proceso. No obstante, se debe tener cierta precaución con esta práctica, porque no todas las valoraciones que se reciban deberían tener la misma consideración. Por un lado, los intereses y propósitos del estudiante que pide opinión y los del estudiante que la proporciona puede que sean diferentes, y por otro lado, puede que la información se encuentre distorsionada por haber pasado por varios intermediarios. En este escenario, los sistemas de recomendación aparecen como herramientas para ayudar a la toma de decisiones generando recomendaciones a los estudiantes sobre un determinado objeto de estudio, a partir de preferencias y opiniones dadas por otros estudiantes que tienen unos intereses o preferencias similares a los suyos. En este proyecto se ha diseñado e implementado una aplicación móvil, fácil de manejar por los estudiantes y que permite que cualquier estudiante registrado en un determinado Grado pueda obtener una recomendación sobre las asignaturas que más le pueden interesar.
A Novel View of Barium Sulfate Deposition in Stainless Steel Tubing
Authors: Lu Alex Yi-Tsung , Ruan Gedeng , Harouaka Khadouja , Sriyarathne Dushanee , Li Wei , Deng Guannan , Zhao Yue , Wang Xing , Kan Amy , Tomson Mason
Published: June 2018

Deposition of inorganic scale has always been a common problem in oilfield pipes, especially in raising safety risk and producing cost. However, the fundamentals of deposition mechanism and the effect of various surface, temperature, flow rate and inhibitors on deposition rate has not been systematically studied. The objective of this research is to reveal the process of barium sulfate deposition on stainless steel surfaces.

In this work a novel continuous flow apparatus has been set up to enable further investigation of deposition rate, crystal size and morphology and the effect of scale inhibitor. In this apparatus supersaturate barium sulfate solution is mixed and passed through a 3 feet stainless steel tubing with ID = 0.04 inch or 0.21 inch at 70 to 120 degree C. The barium concentration is measured at the effluent to quantify the concentration drop. After 1 to 200 hours the tubing is cut into pieces to measure the barite deposition amount and observe the barite crystal morphology using SEM.

Under the experimental conditions, the deposition rate along the stainless steel tubing can be modelled by second order crystal growth kinetics, the SEM micrograph also shows that most of deposited barite is micrometer sized crystals. The highest deposition rate happens at the beginning of the tubing even before the expected induction time of bariums sulfate. The results indicated that the deposition happens even before the mixed solution is expected to form particles, which suggest that the heterogeneous nucleation might be the dominate mechanism in the initial stage, then crystal growth takes place and governs the deposition.

The mechanism of scale attachment to tubing surface has never been well-understood. The apparatus in this work provides a reliable and reproducible method to investigate barium sulfate deposition. The findings in this research will enhance our knowledge of mineral scale deposition process, and aid the use of inhibitors in mineral scale control.
The Effect of Surface Material on the Mechanics of Calcium Carbonate Scale Deposition
Authors: Harouaka Khadouja , Lu Yi Tsung , Ruan Gedeng , Sriyarathne H. Dushanee , Li Wei , Deng Guannan , Zhao Yue , Wang Xin , Kan Amy T , Tomson Mason
Published: June 2018

Calcium carbonate deposition experiments were carried out by pumping a brine solution through PTFE plastic, carbon steel, and 316 stainless steel tubing at 150°C and at a maximum SICaCO3 of 1.36. The kinetics of deposition were inferred from the variation of HCO3- concentration in the effluent with changing flow rate. The inhibition kinetics were determined before, during, and after the addition of NTMP inhibitor into the system. On the metal surfaces, deposition occurred within 10 minutes of the start of the experiment and had similar behavior with changing flow rate, whereas deposition did not begin on the PTFE surface until 30 minutes had passed. No more than 1ppm of NTMP was sufficient to completely halt deposition in the PTFE and stainless steel experiments, whereas up to 2 ppm of NTMP was required in the carbon steel experiment. The deposition kinetics were indistinguishable between the metal surfaces, and were ultimately similar on the smoother hydrophobic PTFE surface once an initial coating of scale had developed. The inhibition efficiency of the NTMP was negatively affected by the corrosion products produced in the carbon steel experiments, assumed to be primarily dissolved Fe (II). Inhibitor retention was higher in the metal surfaces than in the PTFE, possibly due to the preferential adsorption of the NTMP to the surface of the Fe rich steel tubing. Our results suggest that it is the hydrodynamics of brine in the tubing, controlled by flow rate, and the SI that are the main factors controlling scale deposition. Calcium carbonate scale attachment occurs via heterogenous nucleation directly onto the surface of the tube when the brine solution approaches oversaturation from a state of equilibrium with respect to calcium carbonate. The mechanism of inhibition in our system is likely to proceed through the formation of Ca- and Fe-NTMP complexes that either poison the growth surfaces of the scale, or drop the SI of the calcium carbonate by reducing the acitivity of free Ca in the brine.
Recent Experience in Squeeze Treating Huff and Puff Wells for Control of Steamflood Generated Calcium Carbonate Scale
Authors: Thornton Alex , Belhimer Yaz , Smith Ian , Subramaniyan Aravind
Published: June 2018

Steamflooding technology introduction into hydrocarbon recovery operations often brings with it unwanted unavoidable mineral scaling challenges. In this example, steamflood generated calcium carbonate scale caused downhole equipment failure during cyclical steamflood stimulation (CSS) operations. The precipitated scale was effectively removed via mineral acid tubing wash, however mineral acid use for ad-hoc scale dissolving duty added significantly to the corrosion burden of well production tubing strings already regularly exposed to aggressive high concentration mineral acid during near wellbore matrix stimulation treatments. Scale inhibitor squeezing was proposed as a proactive alternative to mineral acid for downhole scale mitigation, and is the subject of this case history. The Middle Eastern heavy oil (HO) field has experience in employing scale inhibitors for topside scale control, but has limited experience in scale squeezing, and no experience of scale squeezing cyclical steam flooded wells. The initiative therefore presented some interesting challenges with respect to the Scale inhibitor selection (thermal stability concerns, compatibility and calcium carbonate efficacy concerns), where to place the scale squeeze in the CSS treatment programme, the squeeze design and its placement within the CSS well, and introduction and execution of routine well scaling health monitors for assessing the performance of the scale squeeze across the full CSS life-cycle.

Detailed bullheaded scale squeeze designs were prepared for two pilot HO field CSS wells that had experienced CaCO3 scaling. Once prepared, the squeeze treatments were quickly scheduled and executed without significant issue - either during treatment application or post-squeeze/steamflood return. The well brine monitors (brine ion composition, residual scale inhibitor and suspended solids) revealed interesting trends during the surveillance phase, but most importantly showed that the scale squeezes performed according to design and successfully maintained the wells free of CaCO3 scale, up to and including the 266 days post-steamflood, at which point routine well produced water sampling was discontinued. After 360 days (at the final review meeting) the field operators advised that both squeezed wells were still in operation and had experienced no scaling downtime.
Novel Laboratory Test Method and Field Applications for Silica/Silicate and Other Problematic Scale Control
Authors: Lu Haiping , Brooks Johnathon , Legan Rick , Fritz Steven
Published: June 2018

The formation of silica and silicate scales caused troublesome issues in various water-handling systems, including steam generators, geothermal wells, and waste-water disposal systems. Recently, a produced water with over 300 ppm of silica, and a spent brine off the strong acid cation (SAC) softeners containing high levels of calcium (Ca), barium (Ba), and magnesium (Mg) were commingled in the production wells. The mixing of these two waters induced silicate as well as other scales, including calcite, barite, etc. In order to provide effective scale inhibition when these waters are mixed, effective scale inhibitors for both silicate and other scales were requested for evaluation.

In this paper, scale inhibitor chemistries for preventing both silica/silicate and other scales were reviewed and the possible synergistic effects were assessed by Design of Experiment (DOE) software. DOE is a systematic method to determine the relationship between several factors, i.e. various chemistries and the performance of formulations under designed application conditions. Selected chemicals were formulated for control of both silica/silicates and other scales, and their performances were evaluated by a Kinetic Turbidity Test (KTT). The KTT is a novel laboratory test method using an Ultraviolet-Visible (UV-Vis) spectrophotometer to monitor the formation of scales at various dosages of tested products. Bottle tests were also conducted for the comparison of inhibition performance.

Based on the lab testing results from the KTT and the bottle tests, the combined products exhibited good scale inhibition performance for both silicate and other scales. The product was recommended for field applications. Subsequent field applications of this product have provided the desired scale control.

This paper presents the laboratory testing data for scale inhibitor selection for the combination products on both silica/silicate control and other scale control by using the efficient performance evaluation method. It also provides an effective product formulation approach for finding synergetic effects of different products. Successful scale inhibitor implementations in the field applications are also presented in this paper. Both laboratory and field testing results show a good case history for the optimization of the silica/silicate and other scale treatment.
Non-Chemical Methods for Downhole Control of Carbonate and Sulphate Scales - An Alternative Approach to Scale Management?
Authors: Heath Stephen , Bin Ruslan Mohd Zahirin , McKay Eric , Ishkov Oleg
Published: June 2018

The deposition of carbonate and sulphate scales is a major problem during oil and gas production. Managing scale with chemical application methods involving either scale prevention and/or removal are the preferred methods of maintaining well production. However, chemical scale control is not always an option, depending upon the nature of the reservoir and well completion and, in cases of severe scaling, the problem can render chemical treatments uneconomic unless other non-chemical methods are utilised.

A variety of non-chemical scale control methods exist, the most common being injection of low salinity brines or low sulphate seawater (LSSW) using reverse osmosis and a sulphate removal plant (SRP) respectively. In addition, careful mixing of lift gas, produced waters and reinjection, coatings, smart well completions with active inflow control devices (ICD) and sliding sleeves (SS) are other methods.

All of these techniques, including combinations thereof, are currently in use and the advantages and disadvantages of the key techniques are compared to chemical methods for both carbonate and sulphate scale control. A detailed example from a North Sea field demonstrates where downhole chemical scale control has not been required through a strategy of careful mixing of lift gas, brines and produced water re-injection. This was combined with understanding fluid flow paths in the reservoir and their likely breakthrough at production wells.

Consideration is given to the injection of smart brines to scale deep in the reservoir, and data from North Sea chalk fields shows how "in situ" geochemical reactions between the reservoir and the injected fluid can precipitate sulphate scales. The necessity to understand these geochemical reactions and their implications for improved oil recovery and the design of smart injection brines for scale control are discussed.

This paper presents a comprehensive review of non-chemical methods for downhole scale control and discusses how the use of these techniques can provide alternative scale management strategies through minimising or alleviating the need for downhole chemical treatments.
Enhancing Scale Inhibitor Squeeze Retention in Carbonate Reservoirs
Authors: Sutherland Louise , Jordan Myles , Champion Nalco
Published: June 2018

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 different mechanisms to retain the inhibitor chemical have been evaluated. Many of these studies have focused on sandstone reservoir with less extensive studies carried out on carbonate substrates.

This paper details work carried out using ‘squeeze life enhancer’ chemicals within the Preflush and Overflush stages utilising a co-polymer containing a quaternary amine group to evaluate this chemicals effect on phosphonate scale inhibitor retention process. Phosphonate scale inhibitors are known to provide excellent squeeze lifetimes in carbonate reservoirs due to their strong interaction with the negatively charged formation using hydrogen ion bonding at low pH or calcium ion bridging at higher pH however with the aid of an enhancer chemical it was hoped to help the retention/release process and so provide further improved squeeze lifetimes. The location of the enhancer chemical within the squeeze process was the focus of the study. Enhancing adsorption of the scale inhibitor is not objective of this application study rather ensuring that the retained chemical is released into the flowing brine during production which is a challenge in carbonate reservoirs.

Laboratory work will be presented which evaluates the effect of using a polyaspartate enhancer within either the preflush or overflush stages to extend the lifetime of a commonly applied phosphonate scale inhibitor. These tests have been carried out using pack floods at 85°C with synthetic Middle East 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 utilised.

The study shows how the different functional groups within the scale inhibitor interact with the carbonate mineral surface and polymer enhancer to extend treatment lifetimes and so potentially reducing the frequency of squeeze treatments and therefore total cost of operations and it is order of application of these chemicals to the rock surface that prove to be critical to the extension observed.
Effect of Magnesium and Ferrous Ions on CaCO3 Scaling in MEG Regeneration Pre-Treatment
Authors: Ma Xiaoguang , Neteland Marte , Broby Margrethe , Andreassen Jens-Petter , Seiersten Marion
Published: June 2018

Monoethylene glycol (MEG) regeneration may include a pre-treatment to reduce the concentration of cations that tend to induce scaling in the downstream process. This work reproduced pre-treatment conditions in a continuous stirred-tank reactor. The experiments were performed in 50 wt% MEG solutions at 80°C. Divalent cations and alkalinity solutions were dosed into the reactor and the mixed solution was pumped out at controlled rates. Steel rods were inserted into the test solution to measure scaling rates. The growth of scale and particles in bulk solution with varying Mg2+, Fe2+ and SO42− ions were studied as function of supersaturation with respect to calcite.

The experimental results show that crystallization fouling, rather than particulate fouling, is the dominating mechanism controlling the formation of calcium carbonate scale in MEG pre-treatment. The supersaturation at steady state controlled the amount of scale. The presence of Mg2+ retarded the nucleation rate of calcium carbonate and thereby lowered the surface areas available for consumption of Ca2+ and CO32− in in the bulk solution. It resulted in higher CaCO3 supersaturation which promoted scaling. Addition of Fe2+ had little effect on scale formation. At these conditions, the calcium carbonate scale that formed on steel rods and as solids in the bulk were exclusively the aragonite polymorph. Seeding with aragonite reduced the scaling tendency in the experiments where Mg2+ was present. The result indicates that maintaining a large active surface area for growth in the bulk solution can reduce the scale formation.
A Novel Evaluation of Scale Inhibitor Performance against Calcium Carbonate Scaling in the Presence of Iron Sulfide
Authors: Russek Jeffrey , Flores Nicole , Brooks Johnathon
Published: June 2018

Scale inhibitors are commonly used for mitigating scale deposition risks in many oil and gas wells worldwide. Of the various chemistries used for scale inhibition, much research has gone into the various conditions in which each chemistry performs best (i.e. temperature, brine solubility, salinity, etc.)4-6. Furthermore, it is known that dissolved iron (Fe2+ and Fe3+) can hinder the performance of scale inhibitors, some more than others3. Thus, applying this knowledge we can extrapolate which inhibitor chemistries might perform best under a given set of conditions. This knowledge can then be applied regionally where most production comes from the same or similar reservoirs and production conditions.

However, less research has been conducted on the effects of pre-existing iron sulfide deposits on the performance of scale inhibitors. Iron sulfide solids are becoming increasingly problematic in the oil field. The combination of iron sulfide with more conventional scaling deposits and the fact that scale inhibitors are surface active and tend to adsorb onto surfaces can yield very challenging situations. This paper discusses testing conducted on various scale inhibitor chemistries and evaluates how exposure to pre-existing FeS solids may impact performance. The various scale inhibitors were evaluated for inhibition performance against a set of controls (no FeS exposure) utilizing the NACE Standard TM0137-2007 "Laboratory Screening Tests to Determine the Ability of Scale Inhibitors to Prevent the Precipitation of Calcium Sulfate and Calcium Carbonate from Solution (for Oil and Gas Production Systems)" with an additional pre-test procedure to expose scale inhibitors in stock solution to a set weight of reagent grade ferrous sulfide (FeS).

Scale inhibitor chemistries evaluated include two polymers (scale inhibitor A and B) and five phosphorous based scale inhibitors (scale inhibitors C through F). The various configurations tested included: scale inhibitors alone, scale inhibitor plus FeS solids, scale inhibitor without FeS plus crude oil, scale inhibitor plus FeS and crude oil. The inclusion of the crude oil allowed an interface for potential micelle interactions. The results indicate scale inhibitors A, C and G were least affected by the presence of FeS with no regard to the presence of crude oil. With this study a scale inhibitor that worked best in the presence of FeS solids for the customer's field in the Permian Basin, where FeS has become an increasing issue, was recommended. This also allowed the customer to treat the FeS solids issue via the method that works best for them.
Scale Formation and Inhibition Study for Water Injection Wells
Authors: Wang Wei , Wei Wei , Ferrier Neil , Arismendi Nayi
Published: June 2018

Produced water can be routely re-injected into reservoir for purposes including pressure support and environmentally acceptable disposal. Scale prevention and control is required to maintain well injectivity and longetivity. This paper presents a comprehensive scale study to reliably access injection well scaling potential and establish fit-for-purpose/optimal scale management strategy. Field water samples were appropriately collected and characterized. Laboratory testing was well designed/conducted to understand scale formation potential, and determine required scale inhibitor dosage. Study results suggest calcite and silicate scales can be of potential concern, and increase of downhole temperature or/and fluid residence time (e.g., under abnormal operation condition with low injection rate or well shut in) at near wellbore formation can lead to higher scaling risk. Testing results show that one scale inhibitor product (originally recommended by chemical vendor) at high dosage can potentially accelerate scale formation leading to more solid precipitation. Alternative inhibitor products were tested and scale inhibitor selection and treatment strategy was optimized based on testing results.
Halite Challenges and Mitigation in the Bakken- Experience of Managing High Saline Produced Water from Hydraulically Fractured Wells
Authors: Zhang Nan , Schmidt Darren , Choi Wanjoo , Sundararajan Desikan , Reisenauer Zach , Freeman Jack , Kristensen Eivind Lie , Dai Zhaoyi , Kan Amy , Tomson Mason
Published: June 2018

Produced water from the Bakken and Three Forks formations in the Williston Basin is notably high in total dissolved solids, which leads to many well maintenance issues related to halite scaling (salt precipitation). Fresh water is widely used to prevent halite scaling; however, initial treatment programs tend to "overtreat" the problem and leads to high operation and maintenance costs. An effort to improve halite scale management has been explored, which includes identification of wells that need fresh water injection; optimization of the fresh water volumes; minimizing deferred oil production; and preventing other scales associated with the presence of fresh water in the wellbore. Several methodologies have been applied to characterize halite scaling and achieve optimization of fresh water treatments. A scaling prediction model was developed and validated with literature data and field data. The model calculates saturation ratios and optimal fresh water volume, which provides critical inputs for treatment recommendations. Field tests have been conducted to dynamically characterize produced fluids. Results have influenced new methods for treatment and fresh water injection techniques. Halite scale inhibitors have also been examined in laboratory and field tests. This work resulted in optimizing both fresh water and chemical treatment programs to minimize halite scaling. Significant cost savings have been achieved from reduced fresh water usage, thereby lowered produced water disposal.
New Test Method for Scale Inhibitor Qualification Verified by Field Testing
Authors: Halvorsen A. M. , Reiersølmoen K. , Andersen K. S. , Brurås A. M. , Sylte A. , Birketveit Ø , Evjenth R. , Du Plessis M. H.
Published: June 2018

A new laboratory test method for qualification of scale inhibitors for carbonate, sulphate and sulphide scale has been demonstrated. The new method reflected conditions at the first stage separator at Gullfaks A in a more realistic way than by use of the more common dynamic tube blocking test. Results of this method have been compared with dynamic tube blocking and static scale inhibition tests and a full-scale field test.

The method developed includes iron particles, realistic H2S and CO2 pressures under anaerobic conditions allowing water chemistry similar to field conditions. The method can be utilised for water with carbonate or sulphate scale potential or a mix. A pH closer to system conditions and scaling on surfaces can be achieved without adjustment of the water composition. The residence time can be up to 5 minutes, which typically represent the residence time in for example separators. The results are interpreted through visual observations through glass coils and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) analyses of steel coils.

Using the new method, significant scale was formed when the incumbent scale inhibitor was tested which was also observed in the field. Several alternative scale inhibitor chemistries were recommended for evaluation based on environmental properties, field experience and cost efficiency. When testing the chemistries with the new method only one inhibitor gave acceptable results (no scaling nor co-precipitation of scale and scale inhibitor). This inhibitor was recommended for further testing in a two-week field test. The field test included quantification of suspended solids and a filter rig test. The results from the field test confirmed the laboratory results showing that the selected inhibitor was more efficient than the incumbent.
Optimization of Scale Treatment Program for Offshore Field Operations with Presence of Iron
Authors: Lee Dong Joon , Srivastava Piyush , Stead Paul , Brooks Johnathon
Published: June 2018

The presence of various levels of iron can be found in field brines primarily due to the mineralogy of the reservoir or from corrosion byproduct (Zhang 2015). The adverse effect of the presence of iron on the performance of scale inhibitors (SI) is known, and if left untreated, can lead to plugging of well tubing and pipelines. It can also cause fouling of separators; resulting in costly remediation and loss of production and revenues.

For the asset under study, traces of carbonate scale and iron sulfide were detected throughout a topsides production system. It was suspected the carbon steel production tubing was corroding over time and the byproduct was reacting with hydrogen sulfide from the souring reservoir. There are a number of well-developed methods that can be implemented to treat corrosion, bacteria, and dissolve the iron sulfide downhole; however, none of these application methods were available for this production system.

This paper will discuss the findings from laboratory testing for carbonate and sulfate scales in the precence of significant levels of iron. In order to select a proper scale inhibitor and the minimum effective concentration (MEC) for this system, a variety of chemistries were screened. Five scale inhibitors were selected for the testing, as shown in Table 1. The findings of the study show, Inhibitor D performed the best in the presence of iron at operationally viable dose rates in both static and dynamic testing conditions favorable for CaCO3, FeCO3, and BaSO4 precipitation.

Table 1 Scale Inhibitor Chemistry Scale Inhibitor Chemistry A DTPMP − Diethylenetriamine penta(methylene phosphonic acid) B BHMT − Bis(Hexamethylene triamine penta) phosphonate scale inhibitor C AEEA − Ethylyethanolamine phosphonic acid E AMPS/AA − (2-methylpropanesulfonic acid and acrylic acid) copolymer based scale inhibitor F TEA − Triethanolamine phosphate ester