Compositional Streamline-Based Modeling of Polymer Flooding Including Rheology, Retention, and Salinity Variation.

The chemical enhanced oil recovery (CEOR) technology that is most used worldwide is polymer flooding due to its proven commercial success at field scale, maturity, and versatility to combine with other technologies. So, there has been an increasing interest in expanding its applicability to more unfavorable mobility ratio conditions and adverse environments (such as high-temperature, high-salinity carbonate reservoirs, pH-sensitive polymers, and formations with active clays). Therefore, a requirement for successful field application is to find the design parameters of the process that balance material requirements and oil recovery benefits in a cost-effective manner, which is usually done through reservoir modeling. Polymer flooding predictive tools normally require detailed information and are based on time-consuming field reservoir simulations. Thus, for effective project management, a quick and sound tool is needed to screen for polymer flooding applications without giving up key physical-chemical phenomena that govern the oil recovery. In this research, we developed a two-dimensional polymer flooding model based on the streamlines approach. This is an alternative to having a multidimensional practical tool thoroughly representing the physical and chemical behavior of polymer flooding by considering key phenomena such as rheology behavior (shear thinning and shear thickening), salinity variations, permeability reduction, and polymer adsorption. Previously published streamline multidimensional models for polymer flooding lack the integrated modeling of the above-mentioned key phenomena. Additionally, the models to represent rheology and retention phenomena in the proposed tool consider a more complete description than the present streamline-based simulators. For the construction of streamlines, we considered a black oil formulation to estimate the pressure and saturation 2D distribution by applying the implicit in pressure and explicit in saturation method, coupled with an explicit formulation for the 2D composition computation. For saturation-composition along the streamlines, the 1D practical tool incorporated represents the polymer flooding key phenomena. The numerical algorithm used by the streamline-based tool is supported by laboratory experiments for waterflooding in homogenous porous media, analytical results for waterflooding in heterogeneous media, polymer flooding field scale simulation cases, and a CMG-STARS model built as a reference for waterflooding in both media (homogenous and heterogeneous) and for polymer flooding. The practical tool developed contributes to simplifying the upscaling from laboratory observations to field applications with better fitted numerical simulation models and to determining favorable scenarios; thus, it could assist in understanding how key parameters affect oil recovery without performing time-consuming CEOR simulations.

Behavioral effects on the offspring of rodent mothers exposed to Tetrahydrocannabinol (THC): A meta-analysis.

Pre and perinatal administration of Tetrahydrocannabinol (THC) in rodents and their offspring has many effects that have been studied using different methods that have not been integrated using quantitative methods. The effect of THC administration on behavior can be better understood by meta-analytic techniques. We examined whether there is an overall effect on the behavior of the offspring when THC is administered to mothers. Eligibility criteria included experiments using an experimental design with a control group without THC, in which THC is administered to mothers during pregnancy and lactation in rodents, and in which at least one type of behavioral (locomotor, emotional or cognitive) measurement in the offspring was implemented. Cohen's d was obtained for each study, then each individual study was weighted, and moderator analysis was performed. Analysis was performed using fixed and random effect models, and the heterogeneity was assessed by calculating Qb, I 2 and the prediction interval. Furthermore, 3 sub-meta-analyses were carried out according to the type of behavior. The general analysis determined a low weighted effect size of THC on the behavior of the offspring, moderated by type of rat strain. The sub-meta-analyses showed a medium effect for cognitive effects of THC in the offspring, and a low effect on locomotor activity and emotional behavior. In addition, publication bias was not detected. More research is needed to contribute to the understanding of the effect of THC exposure on offspring.

Practical Mathematical Model for the Evaluation of Main Parameters in Polymer Flooding: Rheology, Adsorption, Permeability Reduction, and Effective Salinity.

Polymer flooding is one of the most used chemical enhanced oil recovery (CEOR) technologies worldwide. Because of its commercial success at the field scale, there has been an increasing interest to expand its applicability to more unfavorable mobility ratio conditions, such as more viscous oil. Therefore, an important requirement of success is to find a set of design parameters that balance material requirements and petroleum recovery benefits in a cost-effective manner. Then, prediction of oil recovery turns out to handle more detailed information and time-consuming field reservoir simulation. Thus, for an effective enhanced oil recovery project management, a quick and feasible tool is needed to identify projects for polymer flooding applications, without giving up key physical and chemical phenomena related to the recovery process and avoiding activities or projects that have no hope of achieving adequate profitability. A detailed one-dimensional mathematical model for multiphase compositional polymer flooding is presented. The mathematical formulation is based on fractional flow theory, and as a function of fluid saturation and chemical compositions, it considers phenomena such as rheology behavior (shear thinning and shear thickening), salinity variations, permeability reduction, and polymer adsorption. Moreover, by setting proper boundary and initial conditions, the formulation can model different polymer injection strategies such as slug or continuous injection. A numerical model based on finite-difference formulation with a fully implicit scheme was derived to solve the system of nonlinear equations. The validation of the numerical algorithm is verified through analytical solutions, coreflood laboratory experiments, and a CMG-STARS numerical model for waterflooding and polymer flooding. In this work, key aspects to be considered for optimum strategies that would help increase polymer flooding effectiveness are also investigated. For that purpose, the simulation tool developed is used to analyze the effects of polymer and salinity concentrations, the dependence of apparent aqueous viscosity on the shear rate, permeability reduction, reversible-irreversible polymer adsorption, polymer injection strategies on petroleum recovery, and the flow dynamics along porous media. The practical tool and analysis help connect math with physics, facilitating the upscaling from laboratory observations to field application with a better-fitted numerical simulation model, that contributes to determine favorable scenarios, and thus, it could assist engineers to understand how key parameters affect oil recovery without performing time-consuming CEOR simulations.

A supervised clustering MCMC methodology for large categorical feature spaces.

There is a well-established tradition within the statistics literature that explores different techniques for reducing the dimensionality of large feature spaces. The problem is central to machine learning and it has been largely explored under the unsupervised learning paradigm. We introduce a supervised clustering methodology that capitalizes on a Metropolis Hastings algorithm to optimize the partition structure of a large categorical feature space tailored towards minimizing the test error of a learning algorithm. This is a general methodology that can be applied to any supervised learning problem with a large categorical feature space. We show the benefits of the algorithm by applying this methodology to the problem of risk adjustment in competitive health insurance markets. We use a large claims data set that records ICD-10 codes, a large categorical feature space. We aim at improving risk adjustment by clustering diagnostic codes into risk groups suitable for health expenditure prediction. We test the performance of our methodology against common alternatives using panel data from a representative sample of twenty three million citizens in Colombian Healthcare System. Our results outperform common alternatives and suggest that it has potential to improve risk adjustment.

Preparation and Evaluation of Mebendazole Microemulsion for Intranasal Delivery: an Alternative Approach for Glioblastoma Treatment.

Although mebendazole (MBZ) has demonstrated antitumor activity in glioblastoma models, the drug has low aqueous solubility and therefore is poorly absorbed. Considering that other strategies are needed to improve its bioavailability, the current study was aimed to develop and evaluate novel microemulsions of MBZ (MBZ-NaH ME) for intranasal administration. MBZ raw materials were characterized by FTIR, DSC, and XDP. Subsequently, the raw material that contained mainly polymorph C was selected to prepare microemulsions. Two different oleic acid (OA) systems were selected. Formulation A was composed of OA and docosahexaenoic acid (3:1% w/w), while formulation B was composed of OA and Labrafil M2125 (1:1% w/w). Sodium hyaluronate (NaH) at 0.1% was selected as a mucoadhesive agent. MBZ MEs showed a particle size of 209 nm and 145 nm, respectively, and the pH was suitable for nasal formulations (4.5-6.5). Formulation B, which showed the best solubility and rheological behavior, was selected for intranasal evaluation. The nasal toxicity study revealed no damage in the epithelium. Furthermore, formulation B improved significantly the median survival time in the orthotopic C6 rat model compared to the control group. Moreover, NIRF signal intensity revealed a decrease in tumor growth in the treated group with MBZ-MaH ME, which was confirmed by histologic examinations. Results suggest that the intranasal administration of mebendazole-loaded microemulsion might be appropriated for glioblastoma treatment. Graphical abstract.

Experimental-Theoretical Approach to the Adsorption Mechanisms for Anionic, Cationic, and Zwitterionic Surfactants at the Calcite-Water Interface.

The adsorption of surfactants (DTAB, SDS, and CAPB) at the calcite-water interface was studied through surface zeta potential measurements and multiscale molecular dynamics. The ground-state polarization of surfactants proved to be a key factor for the observed behavior; correlation was found between adsorption and the hard or soft charge distribution of the amphiphile. SDS exhibits a steep aggregation profile, reaching saturation and showing classic ionic-surfactant behavior. In contrast, DTAB and CAPB featured diversified adsorption profiles, suggesting interplay between supramolecular aggregation and desorption from the solid surface and alleviating charge buildup at the carbonate surface when bulk concentration approaches CMC. This manifests as an adsorption profile with a fast initial step, followed by a metastable plateau and finalizing with a sharp decrease and stabilization of surface charge. Suggesting this competition of equilibria, elicited at the CaCO3 surface, this study provides atomistic insight into the adsorption mechanism for ionic surfactants on calcite, which is in accordance with experimental evidence and which is a relevant criterion for developing enhanced oil recovery processes.

Detección de displasias corticales asistida mediante métodos semiautomáticos de espesor cortical / Cortical dysplasia detection using semi-automatic cortical thickness methods

Objetivo: Evaluar la detección de displasias corticales utilizando un método semiautomático de cuantificación morfométrica basado en superficie mediante la localización de zonas con espesor cortical anormal. Materiales y métodos: Se seleccionó un grupo de pacientes remitidos por diagnóstico de epilepsia refractaria para la detección de lesiones cerebrales. El espesor cortical se midió utilizando algoritmos automáticos de morfometría basado en superficie de imágenes de resonancia magnética en cada uno de los pacientes, los cuales fueron comparados con un grupo control de sujetos sanos pareados por edad. Resultados: Se realizó la cuantificación de espesor cortical en 4 de los 5 pacientes seleccionados. Se encontraron áreas de engrosamiento cortical en las zonas de displasia cortical conocidas que se relacionaron con las zonas detectadas previamente por el radiólogo en la secuencia FLAIR de cada paciente. Se hallaron diferencias en los mapas de espesor cortical de cada paciente respecto al grupo control. Conclusión: La cuantificación morfométrica de espesor cortical es una técnica que promete ser de utilidad como asistencia computarizada al diagnóstico de las displasias corticales.

Objective: To evaluate the detection of cortical dysplasias using a semi-automatic surface-based morphometric quantification by locating areas with abnormal cortical thickness. Materials and methods: A group selected of patients referred for refractory epilepsy diagnosis to detect brain injury. The cortical thickness was measured using automatic algorithms based morphometry surface of magnetic resonance imaging in each of the patients, which were compared with a control group of age-matched healthy subjects. Results: The quantification was performed cortical thickness in 4 of the 5 patients selected. We found areas of cortical thickening in areas of cortical dysplasia known and related to areas previously identified by the radiologist FLAIR sequence in each patient. We found differences in cortical thickness maps of each patient in the control group. Conclusion: morphometric quantification of cortical thickness is a technique that promises to be useful as diagnostic support to scan cortical dysplasias.

Resonancia magnética de alta definiciónde lesiones intracraneales de la línea media: estudio descriptivo de nueve casos / High-resolution magnetic resonance imaging of midline intracranial lesions: a descriptive study of nine cases

Introducción: La técnica secuencia gradiente de eco tridimensional de campo rápido equilibrado en estado estacionario (3D b-FFE T2) permite visualizar la anatomía cerebral con mayor detalle que las secuencias convencionales para el estudio de la hidrocefalia, la afectación del III y IV ventrículo, el acueducto cerebral y otras estructuras de la línea media. Objetivo: Describir los hallazgos imaginológicos por resonancia magnética de la anatomía y algunas lesiones intracraneales de la línea media, utilizando secuencias 3D b-FFE T2. Materiales y métodos: Se desarrolló un estudio descriptivo de series de casos de nueve individuos de diferentes edades de la ciudad de Medellín, Colombia, en los que se evaluaron alteraciones de la línea media utilizando la técnica 3D b-FFE T2 durante el 2014. Resultados: Se seleccionaron cuatro casos con análisis del III ventrículo, el acueducto, las cisternas basales y sus contenidos por las secuencias convencionales de espín eco o turbo espín eco T1 y T2, y la técnica 3D b-FFE T2. Además, se incluyeron tres casos de hidrocefalia obstructiva, un caso con ventriculostomía, uno con hidrocefalia comunicante y dos con malformaciones vasculares cerebrales evaluados con la técnica 3D b-FFE T2. En todos los casos la secuencia 3D b-FFE T2 mostró en detalle las estructuras y lesiones de la línea media. Conclusiones: La secuencia 3D b-FFE T2 es de utilidad en el planeamiento prequirúrgico y en el seguimiento de la neuroendoscopía o de la ventriculostomía endoscópica del tercer ventrículo. Además, permite visualizar las estructuras y lesiones de la línea media con gran detalle.

Introduction: The three-dimensional balanced fast field echo (3D b-FFE T2) technique provides the visualization of cerebral anatomy with more detail than conventional techniques for the study of hydrocephalus,III and IV ventricular pathology, cerebral aqueduct and other midline brain structures. Objective:To describe imaginological findings by magnetic resonance of anatomy and some intracranial lesions of midline using 3D b-FFE T2 sequences. Materials and methods: A descriptive case series was developed on nine individuals of different age groups from Medellin, Colombia, in which the midlinepathology was evaluated through the 3D b-FFE T2 technique during 2014. Results: Four patients with analysis by conventional T1 and T2 spin echo or turbo spin echo and 3D b-FFE T2 techniques of the III ventricle, cerebral aqueduct, basal cisterns and their content were selected. In addition, three casesof obstructive hydrocephalus, a case with ventriculostomy, one with communicating hydrocephalus and two cases of cerebral vascular malformations evaluated with 3D b-FFE T2 technique were included.In all cases, the 3D b-FFE T2 sequence showed in details the structures and intracranial lesions of the midline. Conclusions: The 3D b-FFE T2 sequence is useful to preoperative planning and follow-up of the neuroendoscopic procedures or endoscopic ventriculostomy of the third ventricle. In addition, it permits to visualize the structures and lesions of midline with detail.

Utilidad de la resonancia magnética y de la tomografía computarizada en el diagnóstico de la enfermedad de las arterias coronarias / Value of magnetic resonance imaging and computed tomography in the diagnosis of coronary artery diseases

Introducción: En los últimos años, el avance en métodos diagnósticos no invasivos como la resonancia magnética y la tomografía computarizada ha permitido la valoración de estructurasanatómicas complejas, con lo que se ha desarrollado un creciente interés en la evaluación de pacientes con sospecha de enfermedad coronaria. Desde el punto de vista radiológico, la valoración de las arterias coronarias ha presentado múltiples retos, incluyendo el tamaño pequeño de las estructuras a evaluar, el movimiento constante del corazón y el movimiento respiratorio.Objetivo: describir los hallazgos imaginológicos y la utilidad diagnóstica de la resonancia magnética y de la tomografía computarizada en pacientes con sospecha de enfermedad coronaria.Materiales y métodos: se realizó un estudio descriptivo de serie de casos para el diagnóstico de pacientes con sospecha de enfermedad coronaria, en una institución de ayudas diagnósticasde alta complejidad de la ciudad de Medellín, Colombia. Resultados: se evaluaron cuatro casos de pacientes con sospecha de enfermedad coronaria. En el primero de la serie se demuestra la utilidad de la angiotomografía coronaria en un paciente con riesgo intermedio y prueba de esfuerzo con ejercicio no concluyente. En los dos casos siguientes, se demuestra la utilidad de la tomografía y la resonancia magnética para valorar las relaciones anatómicas en las anomalías del origen y del curso de estas arterias. Finalmente, se presenta un caso de fístula coronaría y la valoración de esta rara enfermedad por medio de la resonancia magnética...

Introduction: In recent years, advances in noninvasive diagnostic methods, such as magnetic resonance imaging and computed tomography, have allowed the assessment of complex anatomical structures, which has prompted a growing interest in the evaluation of patients with suspected coronary artery disease. From a radiological point of view, assessment of the coronary arteries has presented many challenges, including the small size of the structures to be evaluated, the constant motion of the heart, and respiratory movements. Objective: to describe the imaging findings and the diagnostic usefulness of magnetic resonance imaging and computed tomography in patients with suspected coronary disease. Materials and methods: a descriptive case series on diagnosis of patients with suspected coronary artery disease in a high complexity diagnostic imaging center in Medellin, Colombia. Results: four patients with suspected coronary disease were analyzed. The first of the series, demonstrates the utility of computed tomography angiography for excluding coronary disease in a patient with intermediate risk and inconclusive stress test. The following two cases, demonstrate the usefulness of computed tomography and magnetic resonance imaging to evaluate the anatomical relationships in anomalous origin and course of the coronary arteries. Finally, a case of coronary arterial fistula and its assessment by magnetic resonance imaging is presented...

Enfermedades difusas del hígado: evaluación con resonancia magnética / Diffuse liver disease: evaluation with magnetic resonance

Las enfermedades difusas de hígado hasta finales del siglo XX fueron entidades de difícil diagnóstico por imagen y su confirmación sólo era posible a través de un estudio histopatológico. Actualmente las técnicas avanzadas en resonancia magnética pueden hacer un diagnóstico de estas patologías de una manera más fiable que las demás modalidades por imagen y de una forma no invasiva. Objetivo: describir los hallazgos imaginológicos por resonancia magnética de diferentes enfermedades difusas del hígado Metodología: se realizó un estudio descriptivo tipo series de casos en pacientes con patología difusa de hígado en una institución prestadora de servicios de salud especializada en resonancia magnética. Resultados: se observaron cuatro casos con cirrosis hepática de diferente etiología: uno por virus de la hepatitis B con carcinoma hepatocelular difuso y trombosis maligna de la vena porta, otro por virus de la hepatitis C, el tercero de origen vascular (congestivo) y un último caso de causa alcohólica. De igual manera se evaluaron otros dos casos de esteatosis hepática, uno de ellos con área de respeto focal y otro con infiltración grasa generalizada. En relación con la hemocromatosis secundaria se analizó un caso. Conclusión: la resonancia magnética se convierte en una ayuda diagnóstica no invasiva que no implica exposición a la radiación ionizante, de gran utilidad para el estudio preoperatorio y en el seguimiento de enfermedades difusas del hígado, independiente de su etiología.

Jaundice revealing a k light chain myeloma because of liver light chain deposits.

We report the case of a 77-year-old man referred for jaundice and diagnosed with intrahepatic light chain deposit as primary manifestation of a kappa light chain multiple myeloma. Jaundice is a very rare way of presentation for myeloma. In our observation, diagnosis was made by liver biopsy, which found light chain deposits infiltrating perisinusoidal spaces. We discuss jaundice's possible mechanisms in myeloma.

Factors that affect gastric passage of video capsule.

BACKGROUND: Gastric retention and delayed gastric emptying of the video capsule are major limitations. We retrospectively studied gastric transit time, gastric retention, and completeness of capsule endoscopy (CE) in relation to the conditions in which it was performed. METHODS: From May 2002 to September 2004, CE was performed in 190 patients (92 men; mean age, 58.4 years, range 16-91 years). Patients were stratified according to the way CE was performed (hospital day setting, outpatient, or ongoing hospitalization), and the recordings were analyzed to measure gastric retention, gastric transit time, and the completeness of the examinations. RESULTS: CE examination was performed in a hospital day setting in 100 patients, in an outpatient setting in 61, and during hospitalization in 29. Gastric retention of the capsule occurred in 8 of 190 patients (4.2%) (5 women, 3 men; mean age, 37.9 years). Gastric retention occurred during hospitalization in 7/29 (24.1%) and in hospital day setting in one of 100. Ongoing hospitalization was statistically associated with an increased risk of gastric capsule retention (p < 0.0001). The cecum was reached in 165/190 (87%), and ongoing hospitalization was associated with a lower rate of complete examinations (p < 0.001). Small-bowel transit time was similar, regardless of the circumstances of CE performance. CONCLUSIONS: Ongoing hospitalization is a major cause of gastric retention and incomplete examination by CE. Therefore, CE performance during ongoing hospitalization may require the use of a prokinetic agent.

Is a 2-liter PEG preparation useful before capsule endoscopy?

AIMS: Small bowel contents can sometimes hamper the quality of capsule images. Our aim was to investigate the effect of PEG administered prior to capsule endoscopy (CE) upon quality of images, gastrointestinal transit time, and detection rate of small bowel bleeding lesions in patients with obscure gastrointestinal bleeding. PATIENTS AND METHODS: Forty-two consecutive patients were included. CE was performed following a 12-hour fasting period. The 16 first patients (Group A) received no preparation and the following 27 patients (Group B) received 2 L of PEG the night before. The quality of images was assessed at both in duodenojejunum and ileum level, using a scale including the presence of air bubbles, biliary secretion, and residue (1-4). RESULTS: Quality of images were not different in Group A compared with Group B in the duodenojejunum and in the ileum. Gastric transit time tended to be shorter in Group A compared with Group B (25.5 vs. 45.7 minutes) (P = 0.15), whereas small bowel transit was not different between both groups (271 vs. 288 minutes). Total small bowel CE examination was complete in Group A and in 24 of 26 in Group B (not significant). Potential bleeding lesions were seen in 8 patients in Group A and 12 in Group B (not significant). CONCLUSION: Our retrospective study suggests that 2 L PEG preparation seems able to improve neither the quality of CE images nor its diagnostic performance. Moreover, in our study, PEG tended to increase gastric emptying time and may constitute a limitation for small bowel complete examination.

Diagnostic yield and therapeutic implications of capsule endoscopy in obscure gastrointestinal bleeding.

AIM: The main aim of this study was to evaluate efficacy and therapeutic impact of capsule endoscopy (CE) in obscure gastrointestinal bleeding (OGIB). In addition, we evaluated the software of automatic detection of red zones (SBI, Given Imaging). PATIENTS AND METHODS: From June 2002 to June 2003, thirty-five patients with OGIB underwent capsule endoscopy after negative upper and lower digestive endoscopy. Capsule endoscopy was performed following a 12-hour fasting period and some received 2 L of PEG the night before for bowel preparation. RESULTS: CE was performed for occult (N=18) or overt (N=17) OGIB. Potentially bleeding lesions were found in 16/35 patients (45.7%). Lesions were angiodysplasias (N=8), ulcerations (N=4), tumors (N=2) and active bleeding without visible lesion (N=2). Lesions were located in gastric antrum (N=1), duodenum (N=2) and jejuno-ileum (N=13). Endoscopic (N=10), surgical (N=2) or medical (N=1) treatments were performed in 13/35 (37%). SBI was retrospectively evaluated in 24 patients with sensitivity, specificity, positive and negative predictive value of respectively 45%, 73%, 50% and 69%. CE retention during 10 days occurred in a patient with a small bowel NSAID-induced stricture. CONCLUSION: CE is a safe and effective procedure in the management of OGIB and had a therapeutic impact in more than one third of patients.