Publications by authors named "Oscar Medina"

This paper evaluates solvent-based nanofluids for in situ heavy oil upgrading during cyclic steam stimulation (CSS) applications. The study includes a comprehensive analysis of the properties and characteristics of nanofluids, as well as their performance in in situ upgrading and oil recovery. The evaluation includes laboratory experiments to investigate the effects of the nanoparticle's chemical nature, asphaltene adsorption and gasification, heavy oil recovery, and quality upgrading.

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The effect of temperature and drying technologies on mucilage and cellulose (obtained by the microwave-assisted extraction technique, MAE) from (OFI) and (CC) was determined using a conventional oven (CO) and Refractive Window (RW). Mathematical modeling was performed from drying kinetics data using the Lewis, Henderson-Pabis, Page, and Logarithmic models. Activation Energy (Ea) and Diffusivity (D) were also determined.

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Non-centrifugal cane sugar (NCS) is the second most important Colombian agribusiness in social importance. However, the sugar cane industry is facing some challenges caused by the controversial nutritional and safety attributes of NCS. Some Colombian NCS producers employ natural mucilages as clarifiers; but the uncontrolled application of these components has caused a risk of extinction in the mucilage source plants.

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At present, Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are two highly prevalent disorders worldwide, especially among elderly individuals. T2DM appears to be associated with cognitive dysfunction, with a higher risk of developing neurocognitive disorders, including AD. These diseases have been observed to share various pathophysiological mechanisms, including alterations in insulin signaling, defects in glucose transporters (GLUTs), and mitochondrial dysfunctions in the brain.

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This study focuses on evaluating the volumetric hydrogen content in the gaseous mixture released from the steam catalytic gasification of -C asphaltenes and resins II at low temperatures (<230 °C). For this purpose, four nanocatalysts were selected: CeO, CeO functionalized with Ni-Pd, Fe-Pd, and Co-Pd. The catalytic capacity was measured by non-isothermal (from 100 to 600 °C) and isothermal (220 °C) thermogravimetric analyses.

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Manganese ferrite solid nanospheres (MSNs) were prepared by a solvothermal method and calcined at various temperatures up to 500 °C. Their surface area, morphology, particle size, weight change during calcination, surface coordination number of metal ions, oxidation state, crystal structure, crystallite size, and magnetic properties were studied. The MSNs were used as catalysts to activate potassium peroxymonosulfate (PMS) for the oxidative degradation of para-nitrophenol (PNP) from water and for the oxidation of n-C asphaltenes in flowing air at atmospheric (0.

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Fines migration is a common problem in the oil and gas industry that causes a decrease in productivity. In this sense, the main objective of this study is to develop nanocomposites based on the interaction of quaternary amine (hexadecyltrimethylammonium bromide-CTAB) and MgO to enhance the capacity of retention of fine particles in the porous medium. MgO nanoparticles were synthesized by the sol-gel method using Mg(NO)·6HO as a precursor.

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The main objective of this study is to evaluate the injection of a dispersed nanocatalyst-based nanofluid in a steam stream for in situ upgrading and oil recovery during a steam injection process. The nanocatalyst was selected through adsorption and thermogravimetric experiments. Two nanoparticles were proposed, ceria nanoparticles (CeO), with and without functionalization with nickel, and palladium oxides (CeNi0.

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The main objective of this study is to evaluate the regenerative effect of functionalized CeO nanoparticles with a mass fraction of 0.89% of NiO and 1.1% of PdO in adsorption and subsequent decomposition of -C asphaltenes in steam gasification processes.

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The main objective of this work is the catalyst optimization of Fe₂O₃-, Co₃O₄-, NiO- and/or PdO- (transition element oxides-TEO) functionalized CeO₂ nanoparticles to maximize the conversion of asphaltenes under isothermal conditions at low temperatures (<250 °C) during steam injection processes. Adsorption isotherms and the subsequent steam decomposition process of asphaltenes for evaluating the catalysis were performed through batch adsorption experiments and thermogravimetric analyses coupled to Fourier-transform infrared spectroscopy (FTIR), respectively. The adsorption isotherms and the catalytic behavior were described by the solid-liquid equilibrium (SLE) model and isothermal model, respectively.

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Objective: To compare the efficacy, safety, and tolerability of olanzapine and quetiapine in adolescents with first episode psychosis.

Method: Fifty adolescents (age 16 +/- 1.25) with a first episode of psychosis were randomized to quetiapine or olanzapine in a 6-month open label study.

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Background: Antipsychotic drug discontinuation is a key risk factor in psychotic relapses. Clinical relapse is related to poor outcome, especially in the earlier stages of psychotic illness. The attitude toward treatment during the acute phase of a first episode of psychosis has been proposed as one of the main determinants of treatment discontinuation.

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Objective: To describe the prevalence and correlates of post-traumatic stress disorder (PTSD), depressive and anxiety disorders, or any other mental disorder among adult victims treated in a hospital at different points in time after the 11 March 2004 terrorist attacks in Madrid.

Design, Setting, And Participants: A random sample of 56 individuals injured in the attacks was interviewed in person at one, six, and twelve months after the attacks.

Main Outcome Measures: Current DSM-IV mental disorders: depressive disorders and anxiety disorders (PTSD, generalised anxiety, agoraphobia, social phobia, and panic disorder) were assessed with the Spanish version of the MINI (Mini International Neuropsychiatric Interview), a structured, lay-administered psychiatric interview.

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The best health and nutrition results can be achieved not only from the consumption of fruits and vegetables with high antioxidant capacities, but also from medicinal plants and herbs. Therefore, in the present investigation, the bioactive compounds (polyphenols and flavonoids) and the radical scavenging capacities of Prolipid, a mixture of herbs, were studied. Water extracts showed relatively high capacity of about 61.

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Objective: To examine the diagnostic stability and the functional outcome of patients with early-onset psychosis (EOP) over a 2-year follow-up period.

Methods: A total of 24 patients (18 males (75%) and 6 females (25%), mean age +/- SD: 15.7 +/- 1.

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The purpose of this study is to determine the decrease of neurological soft signs (NSS) during adolescence and to compare this evolutionary process in two groups of adolescents with first episode psychosis: a) schizophrenia and b) non-schizophrenia patients. The structured neurological evaluation scale (NES) was administered to 24 adolescents with first episode psychosis. The number of NSS, the total and subscales scores were correlated with age in patients and in 39 healthy controls.

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Cysticercosis due to Taenia solium infection is endemic in developing countries of the Americas, Asia, and Africa. This study was designed to establish the prevalence of cysticercosis in 158 inpatients of a psychiatric institution in the state of Tachira (Venezuela) and in 127 healthy control subjects. Positive blood tests for cysticercosis by Western blotting were recorded in 18.

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