Solubility and Thermodynamic Parameters of H2S/CH4 in Ionic Liquids Determined by 1H NMR.

Natural gas remains an important global source of energy. Usually, sour gas from the well or refinery stream contains H2S among other contaminants that should be removed to fulfill permissible standards of use. Despite the use of different gas-liquid sour gas upgrading technologies, ionic liquids (ILs) have been recognized as promising materials to remove H2S from sour gas. However, data concerned with thermodynamic solution functions of H2S in ILs have scarcely been reported in the literature. In this work, solution 1H NMR spectroscopy was employed for quantifying H2S soluble in [BMIM][Cl] and for gaining a better understanding of the H2S-IL interaction. Experiments were carried out in a Young-Tap NMR tube containing a saturated solution of H2S/CH4/[BMIM][Cl] and recording spectra from 298 to 333 K. The thermodynamic solution functions, determined from the Van't Hoff equation, showed that solubility of the H2S in the [BMIM][Cl] is an exothermic gas-liquid physisorption process (ΔsolH° = -66.13 kJmol-1) with a negative entropy change (ΔsolS° = -168.19 JK-1 mol-1). 1H NMR spectra of the H2S/[BMIM][Cl] solution show a feature of strong solute-solvent interactions. However, solubility enthalpy is a fifth of the H-S bond energy value. Results from 1H NMR spectroscopy also agree with those from the bench dynamic experiments.

Bioequivalence and Tolerability of Ambrisentan: A Pharmacokinetic Study in Mexican Healthy Male Subjects.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a disease characterized by a progressive rise in pulmonary vascular resistance. Ambrisentan is an oral, propanoic acid based-endothelin receptor antagonist (ERA), selective for the endothelin type-A receptor, which is approved for the treatment of PAH. The Colombia National Food and Drug Surveillance Institute regulatory criteria require demonstrating that the proposed generic product is bioequivalent to its reference-listed drug to obtain marketing approval. OBJECTIVES: The purpose of this study was to test the bioequivalence, pharmacokinetics, and tolerability of ambrisentan 10 mg tablets. METHODS: In this open-label, randomized, oral single-dose, two-way crossover bioequivalence study, 26 Mexican adult healthy male subjects received either the generic product of ambrisentan 10 mg or the reference product Volibris® (ambrisentan) 10 mg tablets during each study period under fasting conditions. There was a 7-day washout period between each dosing. Ambrisentan concentrations in plasma samples were quantified using a validated ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method. Blood samples were collected up to 72 h post-dose in each study period. The primary end points were maximum plasma concentration (Cmax) and area under the plasma concentration-time (AUC0-t) curve between 0 and 72 h for ambrisentan. RESULTS: The ratios (90% CI) of geometric mean for ambrisentan were 104.3% (97.12-111.98%) and 100.2% (95.56-104.72%). These pharmacokinetic parameter values lie within the INVIMA-specified bioequivalence limits of 80%-125%. Nervous system disorders were the most common adverse events (AEs). All AEs were mild to moderate in nature and were resolved after follow-up or pharmacologic treatment. Both products were safe and well tolerated. CONCLUSIONS: The test product ambrisentan 10 mg tablets is bioequivalent to the reference product Volibris® (ambrisentan) 10 mg tablets. Both treatments were well tolerated in the Mexican male population of this study. TRIAL REGISTRATION: COFEPRIS National Clinical Trials Registry number 183300410B0367/2018.

[Safety of gastroenterologist-directed propofol administration for endoscopic procedures: 10-year experience in a private clinic in Lima, Peru]. / Seguridad en la administración de propofol dirigido por gastroenterólogo entrenado en procedimientos endocópicos: experiencia de 10 años en clínica privada en Lima, Perú.

OBJECTIVE: To evaluate safety of propofol combined with Meperidine and Midazolam in colonoscopies, upper endoscopies (EGD) and Endoscopic Ultrasound (EUS) administered by a nurse supervised by a trained gastroenterologist. To compare the required doses of propofol among older and younger than 75 years old. MATERIALS AND METHODS: Retrospective descriptive study including patients 18 years of age and older who received propofol for EGD, colonoscopy (or EGD + colonoscopy) and EUS. The patients were given a baseline dose of Meperidine (25 mg) and Midazolam (1-3 mg) intravenously (IV). After 2-3 minutes, they received an IV bolus of propofol between 10-30 mg. Repeat boluses of 10-20 mg were administered at intervals no lesser than 60 seconds during the procedure, as needed according to patient`s tolerance to the procedure. RESULTS: Between September 2006 and September 2016, 9,704 procedures were performed, of which 1,598 were EGD, 3,065 colonoscopies, 2,492 EGD + colonoscopies and 57 EUS. There were 3,912 women (59.1%), and the average age was 57.1 ± 14.6 years. Eight hundred eighty (12.5%) were older than 75 years. The average dose of propofol for all the procedures was 83.2 ± 48.1 mg, for EGD and colonoscopy was 59.7 ± 36.2 mg and 77.2 ± 41 mg respectively. The average dose used in patients >75 years for EGD was 47.5 ± 37.8 mg, for colonoscopies 58.3 ± 33.4 mg and for EGD + colonoscopies was 78.7 ± 42.7 mg compared to patients <75 years in whom the average dose for EGD was 61.1 ± 35.8 mg (p<0.05), in colonoscopies was 80.5 ± 41.3 mg (p<0.05) and in EGD + colonoscopies 105.9 ± 50.2 mg (p<0.05). There were no sedation-related complications. CONCLUSIONS: Propofol combined with meperidine and midazolam in endoscopic procedures directed by a trained gastroenterologist is safe. Elderly patients (>75 years old) required significantly less doses of propofol for EGD, colonoscopy, EGD/colonoscopy and EUS.

Seguridad en la administración de propofol dirigido por gastroenterólogo entrenado en procedimientos endocópicos: experiencia de 10 años en clínica privada en Lima, Perú / Safety of gastroenterologist-directed propofol administration for endoscopic procedures: 10-year experience in a private clinic in Lima, Peru

Objetivo: Evaluar la seguridad de propofol combinado con meperidina y midazolam en colonoscopías, endoscopías y ecoendoscopía administrado por una enfermera supervisada por un gastroenterólogo entrenado y comparar su requerimiento en pacientes menores y mayores de 75 años. Material y métodos: Estudio descriptivo retrospectivo, que incluyó a pacientes mayores de 18 años de edad que recibieron propofol durante la endoscopía, colonoscopía (o endoscopía+colonoscopía) y ecoendoscopía. A los pacientes se les administró una dosis inicial de Meperidina (25 mg) y Midazolam (1-3 mg) por vía intravenosa (IV). Después de 2-3 minutos recibieron un bolo IV de propofol entre 10-30 mg. Se administraron bolos repetidos de 10-20 mg a intervalos no menores a 60 segundos durante cada procedimiento, titulado según necesidad y tolerancia del paciente. Resultados: Entre septiembre del 2006 y septiembre del 2016, se realizaron 9 704 procedimientos endoscópicos: 1 598 endoscopías, 3 065 colonoscopías, 2 492 endoscopía + colonoscopía y 57 eco-endoscopías. Hubo 3 912 mujeres (59,1%), la edad promedio fue de 57,1 ± 14,6 años, 880 pacientes (12,5%) mayores de 75 años. La dosis media de propofol para todos los procedimientos fue de 83,2 ± 48,1 mg, para la endoscopía y colonoscopía fue de 59,7 ± 36,2 mg y 77,2 ± 41 mg respectivamente. La dosis media utilizada en pacientes mayores de 75 años en endoscopía fue de 47,5 ± 37,8 mg, colonoscopías de 58,3 ± 33,4 mg y endoscopía + colonoscopía de 78,7 ± 42,7 mg en comparación con pacientes < 75 años en los que la dosis promedio de endoscopía fue de 61,1±35,8 mg (p <0,05), en colonoscopías de 80,5±41,3 mg (p<0,05) y en endoscopías+colonoscopías 105,9 ± 50,2 mg (p<0,05). No hubo complicaciones relacionadas con la sedación. Conclusiones: Propofol combinado con meperidina y midazolam en procedimientos endoscópicos, administrado por enfermera y dirigidos por un gastroenterólogo entrenado, es seguro. Los pacientes mayores de 75 años, necesitaron dosis significativamente menores de propofol para endoscopía, colonoscopia, endoscopía + colonoscopia y ecoendoscopía.

Objective: To evaluate safety of propofol combined with Meperidine and Midazolam in colonoscopies, upper endoscopies (EGD) and Endoscopic Ultrasound (EUS) administered by a nurse supervised by a trained gastroenterologist. To compare the required doses of propofol among older and younger than 75 years old. Materials and methods: Retrospective descriptive study including patients 18 years of age and older who received propofol for EGD, colonoscopy (or EGD + colonoscopy) and EUS. The patients were given a baseline dose of Meperidine (25 mg) and Midazolam (1-3 mg) intravenously (IV). After 2-3 minutes, they received an IV bolus of propofol between 10-30 mg. Repeat boluses of 10-20 mg were administered at intervals no lesser than 60 seconds during the procedure, as needed according to patient`s tolerance to the procedure. Results: Between September 2006 and September 2016, 9,704 procedures were performed, of which 1,598 were EGD, 3,065 colonoscopies, 2,492 EGD + colonoscopies and 57 EUS. There were 3,912 women (59.1%), and the average age was 57.1 ± 14.6 years. Eight hundred eighty (12.5%) were older than 75 years. The average dose of propofol for all the procedures was 83.2 ± 48.1 mg, for EGD and colonoscopy was 59.7 ± 36.2 mg and 77.2 ± 41 mg respectively. The average dose used in patients >75 years for EGD was 47.5 ± 37.8 mg, for colonoscopies 58.3 ± 33.4 mg and for EGD + colonoscopies was 78.7 ± 42.7 mg compared to patients <75 years in whom the average dose for EGD was 61.1 ± 35.8 mg (p<0.05), in colonoscopies was 80.5 ± 41.3 mg (p<0.05) and in EGD + colonoscopies 105.9 ± 50.2 mg (p<0.05). There were no sedation-related complications. Conclusions: Propofol combined with meperidine and midazolam in endoscopic procedures directed by a trained gastroenterologist is safe. Elderly patients (>75 years old) required significantly less doses of propofol for EGD, colonoscopy, EGD/colonoscopy and EUS.

The effect of the central donor in bis(benzimidazole)-based cobalt catalysts for the selective cis-1,4-polymerisation of butadiene.

A series of bis(benzimidazole)-based cobalt(II) dichloride complexes containing a range of different central donors has been synthesized and characterized. The nature of the central donor affects the binding of the ligand to the cobalt centre and determines the coordination geometry of the metal complexes. All complexes have been shown to catalyse the polymerization of butadiene, in combination with MAO as the co-catalyst, to give cis-1,4-polybutadiene with high selectivity. The nature of the central donor has a marked influence on the polymerization activity of the catalysts, but does not affect the polymer microstructure. The addition of PPh(3) generally increases the polymerization activity of these cobalt catalysts and results in predominantly (60-70%) 1,2-vinyl-polybutadiene.

An unprecedented alpha-olefin distribution arising from a homogeneous ethylene oligomerization catalyst.

Treatment of the bis(benzimidazolyl)amine chromium complex 2 with ethylene in the presence of MAO affords an exceptionally active oligomerization catalyst and an unprecedented distribution of 1-olefin products in which the C4n series is much more abundant than the C4n+2 series. Deuterium labeling studies are consistent with a metallacyclic chain growth mechanism in which the unusual product distribution arises from the interplay of two sites.

Experimental evidence for large ring metallacycle intermediates in polyethylene chain growth using homogeneous chromium catalysts.

Deuterio-ethylene labeling studies on two homogeneous chromium ethylene oligomerization catalysts show that chain propagation proceeds via metallacyclic intermediates; reactions performed in the presence of 1-nonene show no incorporation of the higher olefin, strongly implicating the involvement of large ring metallacycles.

Marcapaso como terapia en bloqueo cardíaco completo congénito / Artificial pacemaker as therapy in congenital complete heart block

El bloqueo cardíaco completo congénito es una alteración del sistema de conducción cardíaco a nivel del nodo aurículo-ventrícular. Es una entidad poco común y los pacientes que adolecen de la enfermedad suelen ser asintomáticos o bien tener sintomatología desde la vida fetal o en el nacimiento. Cuando desarrollan síntomas, estos pacientes necesitan ser tratados, en forma farmacológica o con el uso de marcapaso artificial. Reportamos los primeros 2 casos de bloqueo cardíaco completo congénito en niños tratados con la implantación de marcapaso permanente en Honduras