Controversies on the mechanism and kinetics of emulsion polymerization: An updated critical review.

Conventional emulsion polymerization (EP) is a process via free radicals whose driving force for its development has been its versatility to generate polymer colloids with ad hoc characteristics for a wide variety of applications, as well as its friendly character to the environment since the continuous medium is water. Although through decades of research, considerable progress has been made in understanding its mechanism and kinetics, some aspects are still not entirely clear. Furthermore, new ideas and experimental results have appeared in the literature that challenge the accepted knowledge about some aspects of EP. This work is a personal vision and an updated critical review on those controversial aspects whose precedent is the review with the same approach published by the author and collaborators almost 20 years ago (J. Macromol. Sci. Part C Polym. Rev., 2004;44:207-229). This review covers advances, aspects that are open to discussion or need improvement regarding what happens in the aqueous phase and in the interface (initiator decomposition, entry and exit of radicals, monomer transport) as well as in the polymer particles (free-radical propagation and termination, swelling, average number of radicals per particle). Special attention is paid to particle formation (nucleation) and its interrelation with colloidal stability and the evolution of the particle size distribution (PSD), which is one of the most fundamental and controversial issues of EP. The Smoluchowski collision rate coefficient to describe diffusion-controlled processes has practically become a paradigm despite the fact that there is evidence that questions its applicability. For this reason, this review also emphasizes this point and the alternatives that have been proposed to mathematically describe the diffusive stages of particle coagulation, the entry of radicals, and the termination reaction. Challenges in improving our understanding of the mechanism and kinetics of emulsion polymerization are pointed out.

Bloqueo caudal más anestesia general balanceada en un paciente con pentalogía de Cantrell, presentación de un caso clínico / Caudal block plus inhaled general anesthesia in a patient with pentalogy of Cantrell, presentation of a clinical case

The pentalogy of Cantrell is a disorder characterized by congenital abnormalities in the abdominal wall, lower sternum, anterior diaphragm, diaphragmatic pericardium, and cardiac anomalies. It is a rare disease with 250 cases registered around the world. The anesthetic implications will require a specialized management given the ventilatory mechanics and cardiac function which are compromised by the disease in the newborn. We present the case of a female patient with pentalogy of Cantrell without prenatal diagnosis, who had an operative procedure to correct patent ductus arteriosus and abdominal mesh placement under balanced general anesthesia with sevoflurane and fentanyl plus caudal block. This case is reported to provide our experience in the anesthetic management of this type of patients.

La pentalogía de Cantrell es una enfermedad caracterizada por anormalidades congénitas de la pared abdominal supraumbilical, esternón inferior, diafragma, pericardio diafragmático y anomalías cardiacas. Se trata de una enfermedad rara con 250 casos registrados alrededor del mundo. Las implicaciones anestésicas requieren de un manejo especializado debido a la mecánica ventilatoria y función cardíaca que se encuentran comprometidas en el recién nacido. Se presenta el caso de una recién nacida portadora de pentalogía de Cantrell, no diagnosticada prenatalmente, quien fue sometida a corrección de ductus arterioso persistente y colocación de malla abdominal bajo anestesia general balanceada con sevofluorano y fentanilo más bloqueo caudal. Se reporta el presente caso para brindar nuestra experiencia en el manejo anestésico de este tipo de pacientes.

Evaluación calórica y sensorial de una mezcla para helado formulado con inulina como sustituto parcial de grasa / Sensory and calorie evaluation of an ice cream mix, where inulin is incorporated as a partial substitute for fat

RESUMEN Se evaluó el aporte calórico, el contenido de grasa saturada y la aceptación sensorial de helados de vainilla formulados con inulina, como sustituto parcial de grasa saturada. Se formularon por triplicado cuatro mezclas para helados, en las cuales, se reemplazó parte de la grasa de palma (2, 3 y 4%) por inulina comercial. La grasa del tratamiento control, se formuló con 7% de grasa vegetal saturada. Para el reemplazo, se utilizó una relación 1:0,25 (grasa saturada:inulina). El aporte calórico, se calculó mediante la medición de energía bruta. El análisis sensorial, se realizó con 23 jueces consumidores habituales de helado. Se concluyó que en la formulación de helados de vainilla es posible reemplazar el 57,14% de grasa vegetal saturada por inulina sin que se afecten las propiedades sensoriales en el producto, logrando reducir en un 16%, el contenido calórico y, en 48,6%, el contenido de grasa saturada. Por lo tanto, la sustitución de grasa vegetal por inulina es una alternativa, que permite ofrecer en el mercado helados funcionales, con bajo contenido calórico, sin perder la palatabilidad, que hace a los helados un producto placentero para la gran mayoría de la población mundial.

ABSTRACT The caloric intake, saturated fat content and sensory acceptance of vanilla ice cream formulated with inulin as a partial substitute for saturated fat was evaluated. Ice cream mixtures by triplicate were formulated, and part of the palm fat (2, 3 and 4%) was replaced by commercial inulin. The fat of the control treatment was formulated with 7% vegetable fat. For the replacement of fat, a ratio of 1: 0.25 (fat: inulin) was used. The caloric intake was calculated by measuring gross energy. The sensory analysis was carried out with 23 habitual consumers judges of ice cream. It was concluded that in the formulation of vanilla ice cream is possible to replace 57.14% vegetable fat for inulin without affecting the sensory properties in the product, with this is possible to obtain 16% reduction in the caloric content and 48.6% in the content of saturated fat. Therefore, the replacement of vegetable fat by inulin is an alternative that allows offering functional ice cream with low caloric content, without losing the palatability that makes ice cream pleasant for most of the world population.

Oil-in-eutectic mixture HIPEs co-stabilized with surfactant and nanohydroxyapatite: ring-opening polymerization for nanocomposite scaffold synthesis.

Mixtures of a nonionic surfactant and non-functionalized nanohydroxyapatite (NHA) enhanced the stability of oil-in-eutectic mixture high internal phase emulsions (HIPEs). Upon ring opening polymerization of the eutectic mixture composed of l-lactide and ε-caprolactone, biodegradable polyHIPEs with specific cavity sizes and selective interfacial functionalization with NHA are produced.

Super-enhanced particle nucleation in styrene emulsion polymerization in the presence of sodium styrene sulfonate.

The styrene (St) emulsion polymerization using Aerosol MA80 as surfactant and in the presence of sodium styrene sulfonate (NaSS) was studied. The effect of NaSS content was assessed using MA80 concentrations below and at the critical micellar concentration. It was found that at the higher NaSS and MA80 contents, the number of particles (N) reaches a maximum of the order of 1017particles/cm3 water, a huge value that has never been reported. In this work an explanation for this super-enhanced particle nucleation phenomenon is proposed. Such hypothesis is based on the role of St-NaSS oligomers formed in the aqueous phase and their synergy with MA80 molecules to provide colloidal stability to the system. The proposal seems to be consistent with the experimental data obtained for the evolution of monomer conversion, N, particles size distribution and the wideness of this latter as well as with a theoretical estimation of the N.

Secuencia de displasia caudal: Estudio clínico y radiológico de un paciente / Caudal dysplasia sequence: Clinical and radiological study of a patient

La secuencia de displasia caudal (SDC), denominada también síndrome de regresión caudal y síndrome de agenesia sacra, es una malformación congénita poco frecuente, que incluye principalmente agenesia con extensión variable de cuerpos vertebrales distales lumbosacrococcígeos y/o sacrococcígeos. En este trabajo se presentan criterios diagnósticos por imagen, clasificación y estudio de un caso clínico.

Caudal dysplasia sequence (CDS), also called caudal regression syndrome and syndrome of sacral agenesis is a rare congenital malformation, which includes agenesis with variable extension of lumbo-sacral-coccygeal distal and sacrococcygeal vertebral bodies. In this article we review diagnostic criteria, classification and report a clinical case.

Gluconeogenesis is not regulated by either glucose or insulin in extremely low birth weight infants receiving total parenteral nutrition.

OBJECTIVE: To determine potential factors regulating gluconeogenesis (GNG) in extremely low birth weight infants receiving total parenteral nutrition. STUDY DESIGN: Seven infants (birth weight, 0.824 ± 0.068 kg; gestational age, 25.4 ± 0.5 weeks; postnatal age, 3.3 ± 0.2 days) were studied for 11 hours, with parenteral lipid and amino acid therapy continued at prestudy rates. Glucose was supplied at prestudy rates for the first 5 hours (period 1) and was then reduced to 6 mg/kg·min for 1 hour and further to ~3 mg/kg·min for 5 hours (period 2). A total of 2.5 mg/kg·min of the glucose was replaced by [U-(13)C]glucose throughout the study for measurements of glucose production and GNG. Concentrations of glucose, insulin, glucagons, and cortisol were determined. RESULTS: GNG and glucose production remained unchanged (2.12 ± 0.23 vs. 1.84 ± 0.25 mg/kg·min [P = NS] and 2.44 ± 0.27 vs. 2.51 ± 0.31 mg/kg·min [P = NS], respectively), despite a 60% reduction of the glucose infusion rate and subsequent 30% (124.7 ± 10.8 to 82.6 ± 8.9 mg/dL; P = .009) and 70% (26.9 ± 4.7 to 6.6 ± 0.4 µU/mL; P = .002) decreases in glucose and insulin concentrations, respectively. Cortisol and glucagon concentrations remained unchanged. CONCLUSION: In extremely low birth weight infants receiving total parenteral nutrition, GNG is a continuous process that is not affected by infusion rates of glucose or concentrations of glucose or insulin.

Specific characteristics of sudden death in a mediterranean Spanish population.

Most of the data reported on sudden cardiac death has been from studies of Anglo-Saxon patients. We conducted a study to ascertain the relation between sudden death (SD) and some epidemiologic, clinical, and biochemical parameters and to assess the coronary histopathologic aspects of subjects in a Spanish population who had died suddenly. A total of 204 subjects (86% men), aged 12 to 80 years (mean 54 ± 15), who had died from out-of-hospital natural SD were evaluated. Only 15% of subjects had been previously diagnosed with heart disease. Pathologic evidence of underlying cardiovascular disease was found in 90% of cases, with coronary heart disease (CHD) the most frequent (58%). The CHD was acute coronary thrombosis in 41% and a stable plaque with luminal narrowing of ≥75% in 59%. An old myocardial infarction was found in 31% of the SD victims. Cardiac hypertrophy was found in 48%, with no relation between the presence of cardiac hypertrophy and CHD. Patients with stable plaques had a greater heart weight than did those with acute coronary thrombosis (p = 0.02). Male gender, older age, smoking, and low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio of ≥3 were associated with CHD. A greater percentage of patients with an eroded and/or ruptured plaque than patients with a stable plaque were smokers. Only smoking and a low-density lipoprotein/high-density lipoprotein cholesterol ratio of ≥3 were associated with an eroded and/or ruptured plaque. In conclusion, compared with the findings from studies of Anglo-Saxon patients, a lower incidence of CHD and acute coronary thrombosis and a greater incidence of cardiac hypertrophy were found in SD victims of a Mediterranean Spanish population.

[Intensive insulin therapy in non-diabetic patients with myocardial infarction and hyperglycemia. INSUCOR study]. / Tratamiento intensivo con insulina en pacientes sin diabetes conocida con infarto de miocardio e hiperglucemia. Estudio INSUCOR.

BACKGROUND AND OBJECTIVE: Hyperglycemia at admission has been associated with bad prognosis in patients with myocardial infarction (MI). The clinical benefit of intensive insulin treatment has been evaluated in diabetic patients admitted to intensive care units. The aim of our study was to assess the short-term effects and the safety of strict glycemic control in subjects with MI and hyperglycemia without a previous history of diabetes. PATIENTS AND METHOD: Twenty-eight non-previously diabetic patients admitted with MI and hyperglycemia were randomized to 2 treatment arms during the first 48 h: a) the intensive group (n = 13) received intravenous insulin with target glycemia levels of 80-110 mg/dl, and b) the conventional group (n = 15) received subcutaneous insulin only when glycemia was 160 mg/dl. High-sensitivity C-reactive protein was determined at 48 h and before discharge. An oral glucose tolerance test was performed after one month. RESULTS: During the first 48 h, glycemia was significantly lower in the intensive than in the conventional group -mean (standard deviation): 104 (8) and 153 (54) mg/dl, respectively (p = 0.002)-, without any clinically significant hypoglycemic episodes. At 48 h, high-sensitivity C-reactive protein was significantly lower in the intensive group -44.3 (35.7) and 20.3 (20.3) mg/ml, respectively (p = 0.04)-. After 4 weeks, only 28.6% of patients showed normal response in the oral glucose tolerance test. CONCLUSIONS: Intensive treatment with insulin to maintain near normoglycemia in non-diabetic patients with MI and hyperglycemia is feasible, safe and more effective than conventional treatment. In addition, it produces attenuation of inflammatory response. Our study also confirms the high prevalence of unknown abnormalities in glucose tolerance in subjects with MI.

Tratamiento intensivo con insulina en pacientes sin diabetes conocida con infarto de miocardio e hiperglucemia. Estudio INSUCOR / Intensive insulin therapy in non-diabetic patients with myocardial infarction and hyperglycemia. INSUCOR study

Fundamento y objetivo: La hiperglucemia en el momento del ingreso se ha asociado con mal pronóstico en pacientes con infarto de miocardio (IM). El beneficio clínico del tratamiento intensivo con insulina se ha evaluado en pacientes diabéticos ingresados en unidades de cuidados intensivos. Nuestro objetivo ha sido evaluar los efectos a corto plazo y la seguridad del control glucémico estricto en pacientes con IM e hiperglucemia sin diabetes conocida. Pacientes y método: Se aleatorizó a un total de 28 pacientes sin diabetes conocida que habían ingresado con IM e hiperglucemia a 2 grupos de tratamiento durante las primeras 48 h: a) grupo de tratamiento intensivo (n = 13), que recibió insulina intravenosa con el objetivo de mantener la glucemia entre 80 y 110 mg/dl, y b) grupo de tratamiento convencional (n = 15), que recibió insulina subcutánea sólo si la glucemia era mayor o igual a 160 mg/dl. La proteína C reactiva ultrasensible se determinó a las 48 h del ingreso y al alta. Se realizó un test de tolerancia oral a la glucosa al cabo de un mes. Resultados: Durante las primeras 48 h la glucemia fue significativamente menor en el grupo de tratamiento intensivo, con una media (desviación estándar) de 104 (8) mg/dl, frente a 153 (54) mg/dl en el grupo de tratamiento convencional (p = 0,002), sin episodios de hipoglucemias sintomáticas. A las 48 h la proteína C reactiva ultrasensible fue significativamente menor en el grupo de tratamiento intensivo que en el de tratamiento convencional ­media de 44,3 (35,7) y 20,3 (20,3) mg/ml, respectivamente (p = 0,04)­. Al cabo de 4 semanas sólo el 28,6% de los pacientes presentaba tolerancia normal a la glucosa. Conclusiones: El tratamiento intensivo con insulina con valores cercanos a la normoglucemia en pacientes no diabéticos con IM e hiperglucemia es factible, seguro y más efectivo que el tratamiento convencional. Además, atenúa la respuesta inflamatoria. El estudio confirma la alta prevalencia de alteraciones de la tolerancia a la glucosa no conocidas en pacientes con IM

Background and objective: Hyperglycemia at admission has been associated with bad prognosis in patients with myocardial infarction (MI). The clinical benefit of intensive insulin treatment has been evaluated in diabetic patients admitted to intensive care units. The aim of our study was to assess the short-term effects and the safety of strict glycemic control in subjects with MI and hyperglycemia without a previous history of diabetes. Patients and method: Twenty-eight non-previously diabetic patients admitted with MI and hyperglycemia were randomized to 2 treatment arms during the first 48 h: a) the intensive group (n = 13) received intravenous insulin with target glycemia levels of 80-110 mg/dl, and b) the conventional group (n = 15) received subcutaneous insulin only when glycemia was 160 mg/dl. High-sensitivity C-reactive protein was determined at 48 h and before discharge. An oral glucose tolerance test was performed after one month. Results: During the first 48 h, glycemia was significantly lower in the intensive than in the conventional group ­mean (standard deviation): 104 (8) and 153 (54) mg/dl, respectively (p = 0.002)­, without any clinically significanyt hypoglycemic episodes. At 48 h, high-sensitivity C-reactive protein was significantly lower in the intensive group ­44.3 (35.7) and 20.3 (20.3) mg/ml, respectively (p = 0.04)­. After 4 weeks, only 28.6% of patients showed normal response in the oral glucose tolerance test. Conclusions: Intensive treatment with insulin to maintain near normoglycemia in non-diabetic patients with MI and hyperglycemia is feasible, safe and more effective than conventional treatment. In addition, it produces attenuation of inflammatory response. Our study also confirms the high prevalence of unknown abnormalities in glucose tolerance in subjects with MI

Amyloid-beta peptide binds to microtubule-associated protein 1B (MAP1B).

Extracellular and intraneuronal formation of amyloid-beta aggregates have been demonstrated to be involved in the pathogenesis of Alzheimer's disease. However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of targets have deleterious effects on cellular functions. In the present study we have shown for the first time that amyloid-beta 1-42 bound to a peptide comprising the microtubule binding domain of the heavy chain of microtubule-associated protein 1B by the screening of a human brain cDNA library expressed on M13 phage. This interaction may explain, in part, the loss of neuronal cytoskeletal integrity, impairment of microtubule-dependent transport and synaptic dysfunction observed previously in Alzheimer's disease.

Dietary glutamate is almost entirely removed in its first pass through the splanchnic bed in premature infants.

Breast milk glutamate is a potential gluconeogenic substrate. However, in piglets, most dietary glutamate undergoes first pass extraction by the gut, limiting its contribution to glucose formation. The objectives of the study were to determine in preterm infants, whether dietary glutamate increases plasma [glutamate] in a dose-dependent fashion and whether glutamate carbon appears in plasma glucose to an appreciable extent. Five enterally fed infants (31 +/- 0 wk; 1555 +/- 131 g) (mean +/- SE) were studied twice (postnatal age 10 +/- 1 d and 17 +/- 1 d, respectively), while receiving an intragastric infusion of glutamate (labeled to 4% +/- by [U-13C] glutamate) at 2.4 (study 1) and 4.8 micromol/kg/min (study 2) for 1.5 h (n=2) or 5 h (n=3). Plasma [glutamate] was 82 +/- 8 microM at baseline, and 84 +/- 11 and 90 +/- 13 microM after glutamate supplementation at 2.4 and 4.8 micromol/kg/min, respectively, values not different from baseline. Plasma [glutamate] was not affected by the duration of the glutamate infusion (1.5 versus 5 h). Plasma 13C glucose enrichment was only 0.3% (after 5 h ingestion of glutamate labeled to 4%) indicating insignificant contribution of dietary glutamate carbon to glucose. Thus, in premature infants, splanchnic extraction is the major fate of dietary glutamate, which is not a significant gluconeogenic substrate in these infants.

Modelo bioeconómico de simulación para orientar la definición del objetivo de selección en el sistema doble propósito / Bioeconomic simulation model to orientate selection objetive definition in dual purpose system

Se describe un modelo determinístico dinámico para la simulación de un sistema de producción de doble propósito, la escala vaca-maute se utilizó para estimar los efectos sobre el margen bruto, resultado de cambios en los niveles productivos generados por mejoramiento genético de las características biológicas involucradas. El modelo se concibió compuesto de al menos dos versiones principales, que se articulan integradamente para alcanzar los objetivos de simulación. La versión descriptiva consistió en la caracaterización de la estructura de un sistema de produccioón doble propósito, escala vaca-maute, ubicado en la cuenca del Lago de Maracaibo, cuyas variables biológicas y económicas constituyeron el andamiaje teórico de referencia. La otra versión se refierio a las ecuaciones matemáticas, las cuales les permitieron completar las fases de análisis y simulación. La validación del modelo fue realizada con datos suministrados por el sistema de registros e información para la ganadería de doble propósito, provenientes del municipio Sucre del estado Zulia. En la fase de experimentación se pudo comprobar que, en las condiciones que se realizó la simulación, las características que podrían integrar el objetivo de selección del sistema doble propósito son, peso adulto y producción de leche, la sihuiente fase en el proceso de definición del programa genéticoserá determinar los indicadores más adecuados que sean necesario evaluar para optimizar el progreso en esas características.

Estudio sobre las teorias de: el triangulo equilatero de Einthoven, el electrodo central de Wilson y las derivaciones Unipolares de Goldberg y de Wilson / Study about theories of: equilateral triangle of Einthoven, Wilson's theory and Unipolar Leads of Goldberg and Wilson

Revisando la literatura original sobre los orígenes del electrocardiograma se encontró que las bases de la teoría de el triángulo equilátero de Einthoven, la teoría de Wilson y las derivaciones unipolares de Goldberg y otras teorías asociadas a estas, no es tan sólida como se cree hoy en día. Utilizando un análisis diferente y original se encontró que en realidad estas teorías están basadas en conceptos erróneos. El hecho de que la suma de los valores de las tres derivaciones estándar es igual a cero se debe a la construcción de estas derivaciones y no como se cree a la veracidad de la teoría del triángulo de Einthoven. Las teorías en que se fundamentan Wilson y colaboradores para demostrar que el potencial del Terminal Central de Wilson es igual a cero son: la teoría del triángulo equilátero de Einthoven y la ley de Kirchhoff. La primera no tiene una demostración científica sólida como se demuestra matemática y experimentalmente en este artículo, y la segunda está relacionada con flujos eléctricos, no con potenciales eléctricos. La suma algebraica de los flujos eléctricos dentro de un circuito eléctrico es la que es igual a cero, no la suma de sus potenciales. Esto se demuestra también matemática y experimentalmente en el artículo

A new interpretation method of surface wave measurements to obtain representative shear wave velocity profiles of soils

This paper presents the reference profile concept and shows that it fits well with measured CXW data. Reference SWV profiles may be obtained in the field almost immediately following the measurements and may be used as representative profiles for site amplification evaluations eliminating the need for computationally intensive inversion solutions used with other Vf-Vs methods.(AU)

Variables bioquimicas relacionadas con la motividad y vitalidad espermatica masculina / Variable biochemicals to relates with the motility and spermatic vitality in the sterility masculinity

Uno de los aspectos mas enganosos de la esterilidad e infertilidad masculina es la ausencia de caracteristicas clinicas evidentes del estado de salud y fisiopatologia del testiculo, por lo que es muy importante realizar un examen minucioso del liquido seminal. En este trabajo, se determinaron 174 examenes seminologicos en pacientes con sospecha de infertilidad y esterilidad, cuyas edades fructuan entre 19 y 50 anos. El grupo de pacientes con astenospernia leve (32 %) presento vitalidad mayor de 80 %, sin embargo el 52 y el 71% de estos pacientes reportaron valores disminuidos o aumentados de los niveles de fructuosa y acido citrico respectivamente. Asimismo los pacientes catalogados con necrospernia minima, moderada severa y muy severa presentaron valores muy aumentados y disminuidos de los niveles de fructuosa y acido citrico.