Jorge C. Ribeiro

Chromatographic and spectroscopic analysis of heavy crude oil mixtures with emphasis in nuclear magnetic resonance spectroscopy: A review

The state of the art in the characterization of heavy crude oil mixtures is presented. This characterization can be done by different techniques, such as gas chromatography (GC), high performance liquid chromatography (HPLC), thin layer chromatography (TLC), infrared spectroscopy (IR), Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Nuclear magnetic resonance spectroscopy is the technique of choice due to its capability to provide information on the chemical nature of individual types of hydrogen and carbon atoms in different and complex mixtures of crude oils. The progress made in the interpretation of the NMR spectra with the development of new NMR techniques and different multivariate data analyses could give relevant information about the identification and characterization of hydrocarbons and their physical and chemical properties. These progresses can improve the refining industries operation as a result of the better knowledge on the crude composition that is fed in the refining process, as well as in the prediction of better operating conditions to obtain refined products with desired specifications and in quantities desirable to meet the market demands. The improvement in the refining operation conditions is reflected in economical benefits.

Influence of Polyphosphoric Acid on the Consistency and Composition of Formulated Bitumen: Standard Characterization and NMR Insights

Over the recent years, bitumen modification with polymers, acids, or mineral fillers has gained relevance to adjust its performance properties. This work reports the use of polyphosphoric acid (PPA) for the modification of formulated bitumen. With this objective, an in-depth literature review on PPA modification was firstly performed. Subsequently, five individual refinery components were selected for the preparation of bitumen blends, namely, asphaltic residue, vacuum residue, and three lube oils extracts. Seven binary/ternary bitumen blends were prepared and then treated with PPA. Afterwards, the five components and the unmodified and PPA-modified bitumen were characterized by standard methods (penetration, softening point, and penetration index), SARA analysis, elemental analysis, and (31)P and (1)H nuclear magnetic resonance (NMR) spectroscopy. The results evidenced higher asphaltenes and lower saturates/resins contents in PPA-modified bitumen. The NMR data suggest that the paraffinic chains became longer, the content of condensed aromatics increased, more substituted aromatic structures appeared, and α-hydrogen in aromatic structures diminished. These findings disclosed the improved consistency and oxidation stability of PPA-modified bitumen blends.

Infarto renal segmentario y factor V de Leiden

Resumen es: Objetivo: El infarto renal es raro y la presentacion clinica inconstante causa dificultades diagnosticas. Aunque la mayoria de los infartos renales son c...

Splenosis: a diagnosis to be considered

The term splenosis applies to the autotransplanted splenic tissue resulting from seeding in the context of past splenic trauma or surgery. We report a 42-year-old man with a history of splenectomy observed for an incidentally found retrovesical mass thought to be an ectopic testicle. The abdominal laparotomy revealed multiple focuses of pelvic splenosis. As splenosis can be diagnosed through specific imaging studies one should always consider it in differential diagnosis of a mass discovered years after splenic surgery or trauma.

Predicting Research and Motor Octane Numbers based on Near Infrared Spectroscopy: Models based on Partial Least Squares Regression and Artificial Neural Networks

Abstract This work focuses on the prediction of research and motor octane numbers of gasolines throughout multivariate statistical analysis, which may significantly increase the celerity of the quality control process. The aim of this work is to compare the performance of two different multivariate models, based on partial least squares regression and artificial networks. The results show that both models predict octane numbers with accuracy, presenting coefficients of determination above 0.95 for the calibration data set. For the test data set, partial least squares model is more accurate, which might indicate the existence of linear correlations between spectral data and octane numbers. The statistical parameters also show that the research octane number prediction is more accurate than the motor octane number.

Renal Sinus Hemangioma Simulating a Complex Cyst

Renal sinus hemangiomas are extremely rare and little is known about these benign mesenchymal tumors. We report a case of a suspected complex renal cyst. Ultrasonography, computed tomography and magnetic resonance were unable to rule out malignancy. The patient underwent nephrectomy, and histology revealed a renal sinus hemangioma without relation to parenchyma. Based on this case we discuss this infrequent pathology.

Ascitis post-histerectomía: retraso en el diagnóstico

Artículo disponible en www.actasurologicas.info DESCRIPCIÓN DEL CASO Mujer de 35 años enviada para histerectomía total de emergencia por hemorragia puerperal tras una cesárea urgente por rotura prematura de la bolsa de las aguas (35 semanas). La paciente recibió el alta hospitalaria el día 8 del postoperatorio, en buen estado clínico y asintomática. Volvió a ingresar 6 días después, con dolor y distensión abdominales e hipertermia. La paciente no presentaba otras molestias importantes (tampoco urinarias). El abdomen estaba distendido y la prueba de la onda de líquido era positiva para ascitis, pero no había signos de irritación peritoneal. Las concentraciones de creatinina en el líquido ascítico estaban muy aumentadas. La tomografía computarizada (TC) abdominal y pélvica reveló la presencia de una cantidad enorme de líquido abdominal, sin alteraciones renales o ureterales. Sin embargo, la fase cistográfica puso de manifiesto un escape en la pared posterior de la vejiga. Se remitió a la paciente para laparotomía exploradora. Se evacuaron más de 10 litros de urinoma intraperitoneal. El tratamiento consistió en enterólisis y limpieza peritoneal, seguidos de cistorrafia, colocación de un catéteter doble J y sondaje vesical. Se administraron los antibióticos adecuados con arreglo al cultivo del líquido ascítico. La evolución posquirúrgica fue favorable. La evaluación a los 3 meses, el análisis y la TC fueron normales.

Massive Hematuria Presenting Case of Alkaline Incrusted Cystitis

Alkaline incrusted cystitis is a rare chronic inflammatory disease characterized by bladder mucosal incrustations of inorganic salts. The genesis is conditioned by a pre-existing mucosal damage, urinary infection by urease-producing bacteria and alkaline urine. We present a severe case of alkaline incrusted cystitis caused by Staphylococcus simulans urinary tract infection and perform the brief review of the clinical, pathological and treatment features of this entity.