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Copyright of Cirugía y Cirujanos is the property of Publicidad Permanyer SLU and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introducción: Ante la necesidad de incremento de la efectividad empresarial e inversionista de la industria agroalimentaria cubana es urgente establecer los principios metodológicos para el desarrollo de sus procesos complementados por la asimilación tecnológica. Objetivo: El objetivo del trabajo es elaborar un procedimiento estratégico que guíe de forma científica y metodológica el desarrollo de procesos agroindustriales complementado con la asimilación de tecnologías. Materiales y Métodos: Se define el procedimiento estratégico de acuerdo a los precedentes y las mejoras requeridas. Se aplica la metodología para los surtidos harina, almidón nativo y almidón gelatinizado acetilado de yuca por asimilación de tecnologías y desarrollo de las etapas de gelatinización, acetilación y secado por aspersión. Resultados y Discusión: Se demuestra a través de la aplicación del procedimiento a los productos de yuca que el incremento de exigencias materiales, energéticas, complejidad tecnológica e inversionista del proceso diseñado para almidón gelatinizado acetilado en relación con los procesos asimilados permite elevar aplicabilidad y valor agregado respecto a los surtidos primarios, permitiendo resultados técnico-económicos y de sensibilidad favorables para todas las variantes en condiciones previstas o gestionadas. Conclusiones: El procedimiento integra y mejora las metodologías precedentes, considerando la asociación con la investigación y desarrollo de procesos, la gestión de la disponibilidad de materias primas y la combinación y modificación de surtidos hasta el máximo grado de aplicabilidad. El mejor comportamiento técnico económico para los productos de yuca se alcanzó para el almidón nativo y el gelatinizado acetilado, demandándose mayor efectividad inversionista en los materiales de menor valor agregado.

Because the need to increase business and investor effectiveness in Cuban agro-food industry, it is urgent to establish methodological principles for its processes development complemented by technological assimilation. Objective: To elaborate a strategic procedure that guides in scientific and methodological way the development of agro-industrial processes complemented with technologies assimilation. Materials and methods: Strategic procedure is defined according to precedents and required improvements. This methodology is applied for following assortments: flour, native starch and acetylated gelatinized cassava starch by technologies assimilation and of the gelatinization, acetylation and spray drying stages were development. Results and Discussion: It is demonstrated through procedure application to cassava products, that the increase in material, energy, technological complexity and investment requirements of designed process for acetylated gelatinized starch in relation to assimilated processes allows increasing applicability and added value to primary assortments, allowing favorable technical-economic and sensitivity results for all variants under planned or managed conditions. Conclusions: This procedure integrates and improves previous methodologies, considering the association with research and development of processes, management raw materials availability and assortments combination and modification to maximum applicability degree. The best technical economic performance for cassava products was achieved for native starch and acetylated gelatinized, demanding greater investment effectiveness in materials with lower added value. [ABSTRACT FROM AUTHOR]

A comparative theoretical study of reactivity of methanol, n-butyl alcohol, tert-butyl alcohol, phenol.p-nitrophenol and p-methylphenol acetylation, through the analysis of the corresponding reaction intermediates was carried out. The acetylation of alcohols is one of the most frequently used transformations in organic synthesis as it provides an efficient and inexpensive means for protecting hydroxyl group in a synthetic process. The activation energies and the reaction intermediates energies, were calculated with two levels of theory DFT (B3LYP) and MP2 combined with basis set 3-21G* and 6-31G*.The calculated values were compared with literature data. The methanol presented the higher reactivity in the acetylation reaction and the DFT/6-31G* method reported the lower energy values. [ABSTRACT FROM AUTHOR]

Aim: Polyamidoamine (PAMAM) dendrimers inherent properties have made it the nanocarrier of choice in the current era of innovation. Dendrimer based products are growing and mushrooming like anything in the current time. Although it suffer from hemolytic toxicity which could be reduced by protecting free amino group. Methods: In the present work alternate acetylated method for PAMAM dendrimers was discussed. 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide Linker was used for acetylation. The acetylated conjugate was evaluated for color reaction, Ultraviolet-visible spectroscopy, Fourier Transform infrared spectroscopy, Differential scanning calorimetric, Nuclear magnetic resonance spectra studies. Results: The PAMAM dendrimers were synthesized using divergent approach and further acetylated. Change in λmax values from 282.0 to 282.5 nm was observed for acetylated dendrimers. Characteristic peak of N-H stretch of primary amine at 3284.16 cm-1 was disappeared due to conversion of primary amine to secondary amine. A new peak of -(CO)-NH stretch was obtained at 1640.28 cm-1 (medium) which shows attachment of acetic acid surface group. The changes in Endothermic peak from 120.56 to 110.40ºC were observed which shows the PAMAM dendrimers surface modifications The peak of -NH2 at 2.99 ppm was replaced by (-NHCOCH3) at 2.42 ppm further supports the proof of acetylation. Conclusions: The spectral data clearly revealed that this approach for acetylation gives considerable amount of acetylation in less time duration with elimination of organic solvent. This method could be employed for regular acetylation of amine terminated nanocarriers. EDC linker mediated capping of amine groups opened a new avenue for acetylation of amine terminated protein/peptides.

En esta investigación, nanofibras de celulosa (CNF) de Chusquea quila fueron usadas como refuerzo del ácido poliláctico (PLA) en la fabricación de membranas en electrospinning. El objetivo de este trabajo fue analizar la incidencia de las CNF en las propiedades mecánicas del PLA. Para demostrar lo anterior, fueron elaboradas membranas sin adición de CNF y membranas con CNF en porcentajes de 1%, 3% y 5% con respecto al peso del PLA. Las CNF y las membranas fueron caracterizadas morfológicamente. Además, las CNF fueron acetiladas para lograr dispersión en el PLA. Asimismo, las membranas fueron sometidas a ensayos de tracción y resistencia al desgarro. Se encontró que la adición del 1% de CNF refuerza el material ante esfuerzos de tracción y desgarro. [ABSTRACT FROM AUTHOR]

Native starches are very useful in the manufacture of pharmaceutical, cosmetic and food products. However, they have important limitations, which can be improved by physical, chemical or enzymatic modifications. Millet and maize starches (reference), were modified at three levels. Physicochemical and pharmaceutics tests were applied to evaluate changes in behavior. Under the same conditions, corn starch achieved higher substitution rates. Acetylation of starches, in more extensive, causes changes in the ability of the starch to trap water. The rates of swelling (swelling power) and sorption increase, as viscosity. There were an improve behavior in the characteristics of the gels and the water uptake. This behavior improves stabilization of gels, with less tendency to syneresis. The gelatinization temperature decreases as acetylation increases. By reducing the gelatinization temperature, gels are obtained in less time and with less energy consumption. The crystallinity profile do not change substantially. There were no significant changes in the pharmaceutics properties of the modified starches compared to the native ones. Higher water uptake in the solid state favors rapid disintegration in tablets. These aspects show a potential use of acetylated millet starch in the pharmaceutical and food industry as a gelling and disintegrating agent. [ABSTRACT FROM AUTHOR]

The aim of the work is to experimentally determine the best reaction conditions for acetylation of cassava starch in aqueous basic medium with acetic anhydride as esterifying agent, starting from native and pregelatinized cassava starch and the full kinetic expression when the starting material is pregelatinized starch for the reactor design and evaluation. It was determined that, in order to achieve an adequate functional behavior in the final product, the best conditions are achieved starting from pregelatinized starch in aqueous suspension at concentration of 10% w/v, with a molar anhydrous/glucose anhydrous unit ratio of 0,5 or higher at 40°C, without gelatinization at the above mentioned concentration. The variables that have the greatest influence are the type of starch, the molar ratio in feeding and the temperature in that order. The interactions between the variables considered have significant and positive effects. The kinetic is of the first order with respect to the active pre-gelatinized starch and to the anhydride and of the second global order. The kinetic constants at fixed temperatures resulted in K1, 25°C = 0.0061 L/mol min and K1, 40°C = 0.0213 L/mol min. The activation energy and frequency factor for this reaction resulted in: E1= 10113.5 J/mol and K01= 0.17 L/mol min. The acetylation reactor size is minimized when the initial concentration of anhydride and temperature are increased. [ABSTRACT FROM AUTHOR]

Asthma is a chronic in ammatory disease of the respiratory tract with a complex genetic background in uenced by the exposition to a series of environmental factors. Genetic studies can only elucidate part of the heritability and susceptibility of asthma and even though several diseases have an evident genetic etiology, only a fraction of the genes involved in their pathogenicity have been identi ed. The epigenetic regulation of the latter is a fact one should bear in mind in order to explain the major triggers of diseases whose understanding is complicated, such as allergies and asthma. External stimulus such as nourishment, stress, physical activity, atmospheric pollution, tobacco smoking and alcohol drinking can induce either gene silencing or gene expression. In this regard, epigenetics can explain how these environmental factors in u- ence our genetic inheritance. There is growing evidence that backs-up the fact that DNA methylation, histone post-translational modi cation and microRNA expression are in uenced by the environment. This helps explaining how several of the risk factors mentioned contribute to the development and inheritance of asthma. In this review, differ- ent environmental factors and their relation with the main epigenetic regulatory mechanisms will be analyzed, as well as their possible role in the development of asthma.

Al saturar la pared celular de la madera con anhídrido acético, se reemplazan los grupos hidroxilos libres de las macromoléculas celulosa y hemicelulosa. Con ello se logra rellenar los espacios moleculares con grupos acetilo y así evitar que éstos reaccionen con las moléculas de agua o con los complejos enzimáticos de los hongos de pudrición. Así, se produce la muerte de los hongos por falta de alimento. Con esta modificación química de la madera también se ha mejorado la estabilidad dimensional y la resistencia a agentes xilófagos. Bajo esta premisa, se evaluó el tratamiento químico de acetilación para la protección de madera de Pinus radiata D. Don. Se empleó una metodología en condiciones de laboratorio que permitió determinar el efecto de la acetilación sobre las propiedades de: contenido de humedad; densidad; absorción de agua; estabilidad dimensional y biodegradación por hongos en madera de Pinus radiata D. Don. Se trabajó con dos tiempos de inmersión en anhídrido acético y dos tiempos en autoclave logrando ganancias en peso que fueron desde 6 a 20%. Se mejoraron algunas propiedades de la madera del Pinus radiata D. Don, tales como: a) la resistencia a la degradación producto de la acción de hongos de pudrición café, dado que las pérdidas de peso en las maderas acetiladas fueron desde 1.38% a 17.43% en comparación con la madera control que alcanzó un 64.94%, con el mismo hongo; b) Con un hongo de pudrición blanca se obtuvieron valores de pérdida de peso en madera acetilada que fueron entre 2.96% y 9.12% en comparación con madera no acetilada que exhibió sólo 17.9%, tras cuatro meses de exposición. Además, se mejoraron las propiedades de estabilidad dimensional y absorción de agua.When woody cell wall is saturated with acetic anhydride, the free hydroxyl groups present on cellulosic structures are replaced. Thus, the capillary spaces are filled with acetyl groups and this replacement avoids further reactions with water or enzymatic degradation provoked by rot fungi. So, the death of different fungi is produced by the lack of food. It has been observed too that this chemical modification has improved the dimensional stability and the resistance to xylophages agents. Under this premise, we conducted a research in order to test acetylation of Pinus radiata D. Don wood as a strategy for their protection. An experimental methodology was used under laboratory conditions to determine the effect of the acetylation on some properties such as: water content; density, water uptake; dimensional stability and biodegradation provoked by rot fungi in Pinus radiata D. Don. Two immersion times of pine wood on acetic anhydride and two times in autoclave were tested (30 and 60 minutes). Thus, observed weight gains ranged between 6 and 20%. We also noted the improvement of other properties such as: a) the resistance to the degradation provoked by brown rot fungi, because in treated wood the weight losses ranged between 1.38% and 17.43% in comparison to control samples which reached 64.94% when the same fungi strain was used; b) when a white rot fungi strain was tested, weight losses ranged between 2.96% and 9.12% for acetylated samples in comparison to untreated pieces which showed 17.9% after 4 months of incubation. Furthermore, the dimensional stability and water absorption capacity improved.

El desarrollo de métodos biocatalíticos ha permitido la preparación de una amplia variedad de productos con alto valor agregado a través de procesos simples, selectivos, económicos y respetuosos con el medio ambiente. En este trabajo se evaluó la transformación microbiana causada por el hongo Aspergillus sp. sobre el sustrato arilpropanoide trans-cinamaldehído. El proceso se llevó a cabo empleando los medios de cultivo líquido Sabouraud y Czapeck-Dox, a temperatura promedio de 24oC, humedad relativa entre 45 y 60% y agitación orbital a 120 rpm. El sustrato se transformó principalmente a los productos metabólicos: 3-fenil-1-propanol, alcohol cinamílico, 3-fenilpropanal, acetato 3-fenilpropílico, acetato de cinamilo, alcohol bencílico, 1-fenilpropanol y 2-fenilpropanol. A partir de los resultados se concluyó que el hongo Aspergillus sp. convirtió inicialmente el trans-cinamaldehído mediante reacciones de reducción, y posteriormente modificó los productos resultantes por esterificación y descarboxilación, generando varios compuestos que se emplean como materias primas en diferentes industrias. Se discute una posible ruta metabólica y el efecto del medio de cultivo en la transformación del sustrato.The development of biocatalytic methods has allowed the preparation of a wide variety of products with high added value through simple, selective, economical and environmentally friendly processes. In this work, the microbial transformation of arylpropanoide substrate trans-cinnamaldehyde using the fungus Aspergillus sp. was investigated. The process is carried out in liquid media culture Sabouraud y Czapeck-Dox to an average temperature 24oC, relative humidity between 45 and 60%, and with agitation at 120 rpm on a orbital shaker. The biotransformation of the substrate generated mainly the metabolic products 3-phenyl-1-propanol, cinnamyl alcohol, 3-phenylpropanal, 3-phenylpropyl acetate, cinnamyl acetate, benzylic alcohol, 1-phenylethanol, and 2-phenylethanol. From the results it is concluded that the fungus Aspergillus sp. initially converted the trans-cinnamaldehyde by reduction reactions, and later modified the products resulting through esterification and decarboxylation. In the process, several compounds used as raw materials in different industries were generated. The metabolic pathway and culture medium effect on substrate transformation are discussed.

El objetivo del trabajo es explorar experimentalmente las condiciones de reacción para la acetilación de almidón de yuca en medio básico acuoso con anhídrido acético como agente esterificante, partiendo de almidón nativo y pregelatinizado de yuca y la expresión cinética completa cuando el material de partida es almidón pregelatinizado con fines de diseño y evaluación del reactor. Se determinó que para alcanzar un comportamiento funcional adecuado en el producto final, las mejores condiciones se alcanzan partiendo de almidón pregelatinizado en suspensión acuosa a concentración del 10 % p/v, a una relación molar anhídrido/unidad de anhidro glucosa igual o superior a 0,86 y a 40 °C, sin gelatinización a la concentración referida. Las variables que mayor influencia ejercen en la acetilación son el tipo de almidón, la relación molar en la alimentación y la temperatura en ese orden. Las interacciones entre las variables consideradas tienen efecto significativo y positivo. La cinética es de primer orden respecto al almidón pregelatinizado activo y al anhídrido y de segundo orden global. Las constantes cinéticas a las temperaturas de trabajo resultaron en K1, 25°C = 0,0061 L/mol min y K1, 40°C = 0,0213 L/mol min. La energía de activación y el factor de frecuencia para esta reacción resultaron en: E1= 10113,5 J/mol y K01= 0,17 L/mol min. El tamaño del reactor de acetilación se minimiza cuando se incrementan la concentración inicial de anhídrido y la temperatura.

Objetivo. Determinar la presencia y secuencia del integrón clase I en un aislamiento clínico de Staphylococcus epidermidis proveniente de un neonato con diagnóstico de sepsis. Materiales y métodos. En una cepa de S. epidermidis, aislada de una muestra de hemocultivo de un neonato, se realizaron las pruebas de identificación microbiológica, susceptibilidad antimicrobiana y la caracterización molecular de los genes aac6´-aph2´´, mecA, el gen de la integrasa intI1 y el gen casete aac6´. Resultados. Se identificó el gen de la integrasa intl1 y mediante secuenciación de nucleótidos se encontró una homología del 78% con las secuencias reportadas en la base de datos del NCBI para bacterias Gram negativas. También se evidenció el casete genético aac6´ presente dentro del integrón clase 1, el cual acetila los aminoglucósidos para conferir resistencia a este antibiótico; como parte de la caracterización molecular se encontró la presencia del gen (aac6´-aph2´´), que codifica para una enzima bifuncional que inactiva a los aminoglucósidos, y el gen mecA que confiere resistencia a los ß-lactámicos. En las pruebas de susceptibilidad se encontró resistencia a ampicilina, oxacilina y gentamicina. Conclusiones. Se reporta por primera vez en Colombia, la secuencia del gen de la integrasa intl1 en un aislamiento de S. epidermidis, proveniente de un recién nacido con sepsis neonatal de la unidad de cuidados intensivos en un hospital de tercer nivel de Bogotá. Esta integrasa ha sido relacionada sólo en integrones clase 1, los cuales se han asociado a multirresistencia en aislamientos clínicos en bacterias Gram negativas. El hallazgo de este mecanismo de resistencia, en el presente estudio realizado en una bacteria Gram positiva, sugiere la relación con transferencia horizontal de genes de resistencia entre especies, efectuado mediante la combinación de elementos genéticos móviles. Lo anterior resalta la importancia de la caracterización molecular de cepas causantes de sepsis para el control epidemiológico de la infección y el tratamiento en neonatos.Objective: To determine the presence and the sequence of the class one integron in a Staphylococcus epidermidis strain isolated from a septic neonatal patient. Materials and methods: The S. epidermidis strain was isolated from a blood culture of a newborn. The microbiological identification, test of sensitivity and molecular characterization of the integrase gene int/1, the cassette gene aac6; aac6´aph2´´ resistant gene to aminoglycoside antibiotics and mecA gene resistant to ß-lactamics were realized. Results: The nucleotide sequence of the integrase gen intl1 in S. epidermidis is reported, which showed a 78% similarity to the reported sequence of the NCBI data base in Gram negative bacteria. The gene cassette aac6 aac6´ (aminoglycoside acetilation) was also identified within the class one integron confering aminoglycoside resistance. Through molecular characterization we also found the aminoglycoside ß-lactamics resistance genes (aac6´aph2´y mecA ´); the susceptibility tests showed resistance to ampicilin, oxacilin and gentamicin. Conclusions: The nucleotide sequence of the integrase gen int/1 is reported for the first time in Colombia in a S. epidermidis strain isolated from a septic neonatal patient, at the neonatal care unit of a third level hospital in Bogotá. This integrase in class one integron was reported, which has shown multiresistance association in clinical isolates in Gram negative bacteria. The resistance mechanism found during this approach realized in Gram negative bacteria showed the evidence of an interspecies horizontal transfer especially by gene transfer or by moving elements such as integrons and gene cassettes.The molecular character of the causing agent of sepsis is important for epidemiological control of the infection and treatment in the newborn.

El almidón extraído de las semillas del fruto de pan (Artocarpus altilis) fue modificado químicamente por acetilación y oxidación, y sus propiedades funcionales evaluadas y comparadas con las del almidón nativo. El análisis proximal reveló que los almidones modificados presentaron contenidos de humedad más altos que el nativo. El contenido de cenizas, proteínas, fibra cruda, y amilosa aparente fue reducido con las modificaciones. Las modificaciones no alteraron la morfología de los gránulos de almidón nativo de A. altilis, presentando forma irregular, en su mayoría ovalados y con superficie lisa. La absorción de agua, poder de hinchamiento y sólidos solubles variaron con las modificaciones químicas realizadas, resultando mayores en el almidón acetilado. En comparación con el almidón nativo, los dos tipos de modificación redujeron la temperatura inicial de gelatinización; el pico de máxima viscosidad se redujo en el almidón oxidado pero aumentó en el acetilado; la viscosidad de la pasta en caliente disminuyó para los almidones modificados, mientras que la viscosidad en frío fue menor en el almidón oxidado y mayor en el almidón acetilado. La estabilidad se incrementó con la acetilación y se redujo con la oxidación. El almidón acetilado presentó el valor más bajo de setback o asentamiento, por lo que hubo una menor tendencia a la retrogradaciónEffect of acetylation and oxidation on some properties of Breadfruit (Artocarpus altilis) seed starch. Starch extracted from seeds of Artocarpus altilis (Breadfruit) was chemically modified by acetylation and oxidation, and its functional properties were evaluated and compared with these of native starch. Analysis of the chemical composition showed that moisture content was higher for modified starches. Ash, protein, crude fiber and amylose contents were reduced by the modifications, but did not alter the native starch granules’ irregularity, oval shape and smooth surface. Acetylation produced changes in water absorption, swelling power and soluble solids, these values were higher for acetylated starch, while values for native and oxidized starches were similar. Both modifications reduced pasting temperature; oxidation reduced maximum peak viscosity but it was increased by acetylation. Hot paste viscosity was reduced by both modifications, whereas cold paste viscosity was lower in the oxidized starch and higher in the acetylated starch. Breakdown was increased by acetylation and reduced with oxidation. Setback value was reduced after acetylation, indicating it could minimize retrogradation of the starch

El Almidón nativo (AN) de arracacha (Arracacia xanthorrhiza Bancroft) fue oxidado (AO) o acetilado (AA) para elaborar películas biodegradables, modificando la concentración de glicerol con el fin de determinar el efecto del tipo de modificación del almidón y la concentración del plastificante sobre las propiedades mecánicas de las películas. Se observó que el tipo de modificación del almidón y la cantidad de plastificante utilizado en la formulación para la obtención de las películas tienen efecto significativo (p

A comparative theoretical study of reactivity of methylamine, aniline, diphenylamine, p-nitroaniline and pmethylaniline acetylation, through the analysis of the corresponding reaction intermediates was carried out. The acetylation of amines is one of the most frequently used transformations in organic synthesis since it provides an efficient and inexpensive means for protecting amino group in a synthetic process. The activation energies and the reaction intermediates energies were calculated with two levels of theory: density functional theory (DFT) with the standard B3LYP and the Møller-Plesset perturbation theory (MP2) combined with the basis set 6-31G*. The calculated values were compared with literature data. The methylamine presented the higher reactivity in the acetylation reaction and the DFT method gave the lower energy values. [ABSTRACT FROM AUTHOR]

Copyright of West Indian Medical Journal is the property of West Indian Medical Journal (WIMJ) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Al saturar la pared celular de la madera con anhídrido acético, se reemplazan los grupos hi-droxilos libres de las macromoléculas celulosa y hemicelulosa. Con ello se logra rellenar los espacios moleculares con grupos acetilo y así evitar que éstos reaccionen con las moléculas de agua o con los complejos enzimáticos de los hongos de pudrición. Así, se produce la muerte de los hongos por falta de alimento. Con esta modificación química de la madera también se ha mejorado la estabilidad dimensional y la resistencia a agentes xilófagos. Bajo esta premisa, se evaluó el tratamiento químico de acetilación para la protección de madera de Pinus radiata D. Don. Se empleó una metodología en condiciones de laboratorio que permitió determinar el efecto de la acetilación sobre las propiedades de: contenido de humedad; densidad; absorción de agua; estabilidad dimensional y biodegradación por hongos en madera de Pinus radiata D. Don. Se trabajó con dos tiempos de inmersión en anhídrido acético y dos tiempos en autoclave logran-do ganancias en peso que fueron desde 6 a 20%. Se mejoraron algunas propiedades de la madera del Pinus radiata D. Don, tales como: a) la resistencia a la degradación producto de la acción de hongos de pudrición café, dado que las pérdidas de peso en las maderas acetiladas fueron desde 1.38% a 17.43% en comparación con la madera control que alcanzó un 64.94%, con el mismo hongo; b) Con un hongo de pudrición blanca se obtuvieron valores de pérdida de peso en madera acetilada que fueron entre 2.96% y 9.12% en comparación con madera no acetilada que exhibió sólo 17.9%, tras cuatro meses de exposición. Además, se mejoraron las propiedades de estabilidad dimensional y absorción de agua. Abstract When woody cell wall is saturated with acetic anhydride, the free hydroxyl groups present on ce-llulosic structures are replaced. Thus, the capillary spaces are filled with acetyl groups and this repla-cement avoids further reactions with water or enzymatic degradation provoked by rot fungi. So, the death of different fungi is produced by the lack of food. It has been observed too that this chemical modification has improved the dimensional stability and the resistance to xylophages agents. Under this premise, we conducted a research in order to test acetylation of Pinus radiata D. Don wood as a strategy for their protection. An experimental methodology was used under laboratory conditions to determine the effect of the acetylation on some properties such as: water content; density, water uptake; dimensional stability and biodegradation provoked by rot fungi in Pinus radiata D. Don. Two immersion times of pine wood on acetic anhydride and two times in autoclave were tested (30 and 60 minutes). Thus, observed weight gains ranged between 6 and 20%. We also noted the improvement of other properties such as: a) the resistance to the degradation provoked by brown rot fungi, because in treated wood the weight losses ranged between 1.38% and 17.43% in comparison to control samples which reached 64.94% when the same fungi strain was used; b) when a white rot fungi strain was tested, weight losses ranged between 2.96% and 9.12% for acetylated samples in comparison to untreated pieces which showed 17.9% aft er 4 months of incubation. Furthermore, the dimensional stability and water absorption capacity improved.

La estabilidad dimensional de muestras sólidas modificadas químicamente de las especies maderables tropicales Teca (Tectona grandis) y Melina (Gmelina arborea) fue estudiada. Las muestras de ambas especies fueron modificadas utilizando anhídrido acético como reactivo, y el tiempo de reacción fue cambiado con la finalidad de obtener distintos valores de ganancia en peso (WPG). La estabilidad dimensional fue determinada por medio de cinco ciclos de impregnación con agua y secado de las muestras en un horno. Los cambios en el volumen fueron medidos para calcular el coeficiente volumétrico de hinchazón (S%) y la eficiencia de anti-encogimiento (ASE%). Se encontró que el S% disminuye confome incrementa el tiempo de reacción y que el ASE% incrementa a mayor tiempo de reacción para ambas especies, con lo cual, se mejora la estabilidad dimensional de ambas especies tropicales.

El objetivo del presente estudio fue la extracción y caracterización de l-carnitina en aguacate (Persea americana) a través de técnicas instrumentales y computacionales. la cuantificación de l-carnitina de dos variedades de aguacate (booth 8 y fuerte) se realizó mediante espectrofotometría uv/vis. se encontró que la variedad booth 8 tiene un contenido de 84 μg de l carnitina/gramo de fruto fresco, mientras que la fuerte, 82 μg/g. además, se determinó la cinética de reacción de acetilación de la l-carnitina por medio de espectrofotometría de infrarrojos. como resultado se obtuvo una reacción de segundo orden global con una constante de velocidad de 4.45x10 l/mol·s a 298±2K. Por último, se realizó el análisis termodinámico de la reacción, se determinó el mecanismo de reacción y el análisis de reactividad y selectividad de las moléculas reactantes mediante técnicas computacionales, con el método b3lYP y el conjunto de bases 6 311g (d,p). la entalpía de reacción fue de –8.2 kcal/mol en fase gaseosa y de –4.1 kcal/mol en fase acuosa. se estableció que la reacción de acetilación se produce por un ataque nucleofílico del hidrocloruro de l-carnitina al cloruro de acetilo, pasa por la formación de un estado de transición tetraédrico y culmina con la eliminación de ácido clorhídrico. se determinó que la l carnitina es una molécula nucleofílica con el oxígeno como sitio activo, mientras que el cloruro de acetilo es el electrófilo y su sitio activo es el carbono carbonílico.

Copyright of Revista Alergia de Mexico is the property of Coleg. Mexicano de Inmunologia Clinica y Alergia A.C.; Soc. Lat. de Alergia, Asma e Inmunologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wood samples of two tropical hardwood species, Cedar Mary (Calophyllum brasiliense Cambess.) and Guanacaste (Enterolobium cyclocarpum (Jacq.) Griseb.), growing in Costa Rica were chemically modified by acetylation. Acetic anhydride was used as reagent and donor of the acetyl group, potassium carbonate as a catalyst and N,N-dimethylformamide (DMF) as a solvent. The reaction was carried out at 90° C and three reaction times were studied in order to determine the percentage weight gain (PWG) for every treatment. For the seven hour reaction, PWG was 12.88 % and 12.44 % for Guanacaste and Cedar Mary samples respectively. IR spectra using ATR technology were obtained in order to corroborate the reaction. Results showed characteristic signals of functional groups C = O (1737 cm-1), C-O (1220 cm-1) and C-H bending vibration for the acetyl group (1368 cm-1), which indicates that hydroxyl groups had been replaced by acetyl groups. Longer reaction times increase this replacement in both species. [ABSTRACT FROM AUTHOR]

When woody cell wall is saturated with acetic anhydride, the free hydroxyl groups present on cellulosic structures are replaced. Thus, the capillary spaces are filled with acetyl groups and this replacement avoids further reactions with water or enzymatic degradation provoked by rot fungi. So, the death of different fungi is produced by the lack of food. It has been observed too that this chemical modification has improved the dimensional stability and the resistance to xylophages agents. Under this premise, we conducted a research in order to test acetylation of Pinus radiata D. Don wood as a strategy for their protection. An experimental methodology was used under laboratory conditions to determine the effect of the acetylation on some properties such as: water content; density, water uptake; dimensional stability and biodegradation provoked by rot fungi in Pinus radiata D. Don. Two immersion times of pine wood on acetic anhydride and two times in autoclave were tested (30 and 60 minutes). Thus, observed weight gains ranged between 6 and 20%. We also noted the improvement of other properties such as: a) the resistance to the degradation provoked by brown rot fungi, because in treated wood the weight losses ranged between 1.38% and 17.43% in comparison to control samples which reached 64.94% when the same fungi strain was used; b) when a white rot fungi strain was tested, weight losses ranged between 2.96% and 9.12% for acetylated samples in comparison to untreated pieces which showed 17.9% after 4 months of incubation. Furthermore, the dimensional stability and water absorption capacity improved. [ABSTRACT FROM AUTHOR]

Arracacha (Arracacia xanthorrhiza Bancroft) native starch (NS) was oxidized (OS) or acetylated (AS) to produce biodegradable films, changing the concentration of glycerol in order to determine the effect of modifying the starch type and concentration of the plasticizer on the mechanical properties of the films. It was observed that the type of modification of starch and the amount of plasticizer used in the formulae to obtain the films have significant effect (p<0.01) in tensile strength (TS), percent elongation at break (%E) and elasticity modulus (EM). When using AS for the production of films, a greater value in the average TS was reached and this is greater when using lowest amount of plasticizer. While using NS, higher average %E was achieved and this is greater when using higher amount of plasticizer. Among the two factors that affect the mechanical properties of the films obtained, there was not interaction. [ABSTRACT FROM AUTHOR]

Copyright of Archivos Latinoamericanos de Nutrición is the property of Sociedad Latinoamericana de Nutricion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work was aimed at assessing the decay resistance of acetylated Scots pine (Pinus sylvestris) sapwood against white (Coriolus versicolor) and brown (Coniophora puteana) rot fungi and the effect of pyridine as catalyst. Samples were decayed over pure cultures on 4% malt agar for twelve weeks, following the general procedures of the European Standard EN113. Additionally, the dimensional stability of wood given by acetylation was compared in the catalysed and uncatalysed chemical modification systems. The chemical modification provided resistance to the biodegradation of the wood against brown and white rot fungi. A greater level of acetylation was required to inhibit the brown rot, in comparison with the required level to prevent the white rot. The decay patterns and the weight loss recorded indicated that, pyridine as a catalyst did not influence the decay resistance of acetylated wood, when results were compared within the same fungus species. The dimensional stability provided by acetilización, and measured by the antiswelling efficiency (ASE), was satisfactory in both reaction systems, although the uncatalysed system was significantly more efficient. It was concluded that the weight percentage gain due to chemical modification is a good indicator of the degree of permanent partial swelling of the wood blocks, as well as of the dimensional stability and the resistance to decay of the acetylated wood. [ABSTRACT FROM AUTHOR]