Cyclodextrins: Properties and Applications.

Cyclodextrins (CDs) are cyclic oligosaccharides that contain at least six d-(+)-glucopyranose units linked by α-(1, 4) glucosidic bonds [...].

Effect of 1,2-propanediol on the Critical Micelle Concentration of Decyltrimethylammonium Bromide at Temperatures from 293.15 K to 308.15 K.

It is well known that polar organic compounds, such as alcohols and polyols, exert an appreciable influence on water structure and thus have important effects on surfactant micellization. These substances are often used to modify the properties of surfactants in aqueous solutions, increasing the practical applications they have in diverse industries. In this work, the critical micelle concentration (CMC) of decyltrimethylammonium bromide (C10TAB) in water and in 1,2-propanediol aqueous solutions was determined from both sound velocity and surface tension measurements as a function of surfactant concentration in the temperature range of (293.15 to 308.15) K. The critical micelle concentration of the surfactant increases as the concentration of 1,2-propanediol becomes higher, while the effect on temperature does not show important changes within the range considered. At the selected temperatures, the standard thermodynamic parameters of micellization suggests that the addition of 1,2-propanediol makes the micellization process less favorable. Thermodynamic analysis suggests that the micelle formation of C10TAB is an entropy-driven process at the temperatures considered in this study.

Photocatalytic Degradation of Dielectric Mineral Oil with PCBs Content Coupled with Algae Treatment.

Insulating oil contaminated with polychlorinated biphenyls (PCBs) is an environmentally important pollutant. This research focused on the establishment of the optimum conditions under which photocatalytic oxidation can be used together with biotreatment using the Nostoc sp. microorganism to degrade PCBs present in used dielectric oils. Among the optimal conditions studied were PCB concentration, initial pH, and titanium dioxide (TiO2) concentration for the photocatalytic step, and PCB concentration and photoperiod for the biotreatment step. The results indicate that the optimal conditions necessary for photocatalytic degradation were a pH of 6.10, 113 mg/L TiO2, and 765 mg/L PCBs, achieving close to 90% removal. For the biotreatment step, the results showed that PCBs progressively inhibited the microbiological growth, with the lowest cellular growth observed in the medium with the highest PCB concentration.

Limiting diffusion coefficients of [Formula: see text],[Formula: see text]-amino acids in water and in sodium chloride aqueous solutions at 298.15 K.

Transport properties of model compounds in aqueous solutions such as amino acids can provide valuable information in order to understand the complex interactions in aqueous solutions as well as the protein stability in water and the relevant factors involved. Informations about the diffusion of amino acids in water and in aqueous solutions of sodium chloride are very scarce, especially for the 5-aminopentanoic acid and 6-aminohexanoic acid. In this study, limiting binary mutual diffusion coefficients at 298.15 K of 5-aminopentanoic and 6-aminohexanoic acids in aqueous solutions of NaCl 0.15 mol kg-1, using the Taylor dispersion technique, were determined and the results compared with the limiting binary mutual diffusion coefficients for 2-aminopentanoic acid, and 2-aminohexanoic acid, obtained in the same experimental conditions. The discussion of the properties of the selected amino acids is centered on the positions of the ionic groups in the hydrocarbon chain and, in addition, we have discussed the effects of NaCl on their structures and properties. The data on diffusion properties are supported by 1H, 13C and 23Na NMR experiments, which we have obtained for 5-aminopentanoic and 6-aminohexanoic acids, in aqueous solution, also in the presence of NaCl.

Limiting values of diffusion coefficients of glycine, alanine, α-amino butyric acid, norvaline and norleucine in a relevant physiological aqueous medium.

The side chain effect on transport in ionic aqueous salt solutions was investigated for [Formula: see text]-amino acids glycine, alanine, [Formula: see text]-amino butyric acid, norvaline, and norleucine --that together define a chemical homologous series based on the length of the characteristic side chain which increases from zero to four carbons, respectively. Binary mutual diffusion coefficients at infinitesimal concentration in aqueous solutions of NaCl (0.15 mol kg -1) are measured by means of Taylor dispersion technique for this series and significant differences were found against previous published results for identical systems in pure water. In this way, NaCl effect on the transport of each amino acid is thus assessed and discussed in terms of salting-out effects. Also, solvated Stokes hydrodynamic radii were computed for the series showing comparable results in water and NaCl solution. The new information should prove useful in the design and characterization of transport-controlled systems in physiological and pharmacological studies.

Effect of tempeaature and concentration on the iscosity of aqueous solutions oof 3-aminopropanoic acid, 4-aminobutanoic acid, 5-aminopentanoic acid,6-aminohexanoic / Acid efecto e laa temperatura y la concentración en la viscoidad de solucioones acuosas de ácido 3-aminopropanoico, ácido 4-aminobutanoico, ácido 5-aminopentanoico, ácido 6-aminohexanoico / Efeito da temperatura e a concentraçâo na viscosiade das soluções aquosas de áciido 3-aminopropanoico, ácido 4-aminobutanoico, ácido 5-aminopentanoico, ácido 6-aminohexanoico

In this work we present the effect of temperature on the viscosities of aqueous so-lutions of 3-aminopropanoic acid, 4-ami-nobutanoic acid, 5-aminopentanoic acid and 6-aminohexanoic acid as a function of concentration. The experimental mea-surements were done from 293.15 K to 308.15 K. At each temperature the experimental data were fitted to the Tsangaris-Martin equation and the B viscosity coefficient was determined. The dependence of the B coefficients on the number of carbon atoms of the amino acids is linear, so the contribution of polar and apolar groups was established. The results are interpreted in terms of amino acid hydration.

En este trabajo se presenta el efecto de la temperatura sobre las viscosidades de soluciones acuosas de acido 3-aminopro-panoico, acido 4-aminobutanoico, acido 5-aminopentanoico, acido 6-aminohexa-noico en función de la concentración. Las determinaciones experimentales se realizaron en un intervalo de temperatura entre 293,15 K hasta 308,15 K. A cada una de las temperaturas trabajadas, los datos experimentales se ajustaron a la ecuación de Tsangaris-Martin y se determinó el coeficiente B de viscosidad. La dependencia del coeficiente B con el número de carbonos del aminoácido es lineal lo cual permitió establecer la contribución de los grupos polares y apo-lares del aminoácido. Los resultados se interpretan en términos de la hidratación de los aminoácidos.

Neste trabalho é apresentado o efeito da temperatura sobre as viscosidades das soluções aquosas de ácido 3-aminopro-panoico, ácido 4-aminobutanoico, ácido 5-aminopentanoico, ácido 6-aminohe-xanoico em função da concentração. As determinações experimentais foram feitas em um intervalo de temperatura entre os 293,15 K até 308,15 K. Para cada uma das temperaturas trabalhadas, os dados experimentais foram ajustados à equação de Tsangaris-Martin, e o coe-fciente B de viscosidade foi determinado. A dependência do coeficiente B com o número de carbonos do aminoácido é linear e permitiu estabelecer a contri-buição dos grupos polares e apolares do aminoácido. Os resultados foram interpretados em termos da hidratação dos aminoácidos.

INFLUENCE OF 1-BUTANOL, 1,2-BUTANEDIOL AND 1,2,3,4-BUTANETETROL ON THE ADSORPTION OF b-LACTOGLOBULIN AT THE AIR-WATER INTERFACE / INFLUENCIA DE 1-BUTANOL, 1,2-BUTANODIOL Y 1,2,3,4-BUTANOTETROL EN LA ADSORCIÓN DE b-LACTOGLOBULINA EN LA INTERFASE AIRE-AGUA / INFLUÊNCIA DE 1-BUTANOL, 1,2-BUTANODIOL E 1,2,3,4-BUTANOTETROL NA ADSORÇÃO DE b-LACTOGLOBULINA NA INTERFACE AR-ÁGUA

In this work, a systematic study on the effect of 1-butanol, 1,2-butanediol and 1,2,3,4-butanetetrol (erythritol) on the surface tension of β-lactoglobulin in aqueous solution at pH 6.5 and 298.15 K is presented. The experimental data were used to calculate the surface pressure and were adjusted to different protein adsorption models at the liquid-air interface to explain the behavior of β-lactoglobulin in aqueous solution. The results show that the alcohols produce a significant effect on the adsorption behavior of the protein at the interface that is related to the number of hydroxyl groups.

En este trabajo se presenta un estudio sistemático del efecto de 1-butanol, 1,2-butanodiol y 1,2,3,4-butanotetrol (eritritol) sobre la tensión superficial de la β-lactoglobulina en solución acuosa a 298,15 K. Los datos experimentales fueron usados para calcular la presión superficial y se ajustaron a distintos modelos de adsorción en la interfase líquido-aire para explicar el comportamiento de la β-lactoglobulina en solución acuosa. Los resultados muestran que los alcoholes tienen un efecto significativo en el proceso de adsorción de la proteína en la interfase, relacionado con el número de grupos hidroxilo del alcohol.

Neste trabalho, um estudo sistemático sobre o efeito do 1-butanol, 1,2-butanodiol e 1,2,3,4-butanotetrol (eritritol) sobre a tensão superficial da β-lactoglobulina em soluçãoaquosa em pH 6,5 e 298,15 K é apresentado. Os dados experimentais foram utilizados para calcular a pressão de superfície e foram ajustados para diferentes modelos de adsorção de proteínas na interface líquido-ar para explicar o comportamento de β-lactoglobulina em soluçãoaquosa. Os resultados mostram que os alcoóisproduzem um efeito significativo sobre o comportamento de adsorção da proteína na interface que está relacionado com o número de grupos hidroxila.

Partial molar vllume of some alkanolamines in water at 298.15 k / Volumen molar parcial de algunas alcanolaminas en agua a 298,15 k / Volume molar paccial de algumas alcanolaminas em água a 298,15 k

Densities of aqueous solutions of 3-amino-1-propanol, 2-amino-1-propanol, 3-amino-1,2-propanediol, and 1,3-diamino-2-propanol were measured at 298.15 K using the vibrating tube technique. The apparent molar volumes of the alkanolamines were determined as a function of composition from experimental data and the solute limiting partial molar volume was obtained through extrapolation. The results are discussed in terms of the effect of the number and the position of polar groups in the molecules.

Las densidades de soluciones acuosas de 3-amino-1-propanol, 2-amino-1-propanol, 3-amino-1,2-propanodiol y 1,3-diamino-2-propanol fueron medidas a 298,15 K usando la técnica del tubo vibrante. Los volúmenes molares aparentes se determinaron en función de la composición a partir de los datos experimentales y los volúmenes molares parciales de los solutos a dilución infinita fueron obtenidos por extrapolación. Los resultados son discutidos en términos del efecto del número y la posición de los grupos polares en las moléculas.

As densidades de soluções aquosas de 3-amino-1-propanol, 2-amino-1-propanol, 3-amino-1,2-propanediol and 1,3-diamino-2-propanol foram medidas a 298 K utilizando a técnica de tubo vibratório. Os volumes molares aparentes das alcanolaminas foram determinados como uma função de composição partindo de dados experimentais e parciais volumes molares de solutos na diluição infinita foram obtidos por extrapolação. Os resultados são discutidos em termos do efeito do número e da posição dos grupos polares nas moléculas.

EFECTO DE ALCOHOLES Y POLIOLES SOBRE LA ESTABILIDAD ESTRUCTURAL DE LA β-LACTOGLOBULLNA EN SOLUCIÓN ACUOSA / EFFECT OF ALCOHOLS AND POLYOLS ON THE STRUCTURAL STABILITY OF β-LACTOGLOBULLN IN AQUEOUS SOLUTION / EFEITO DE ALCOÓIS E POLIOLES SOB A ESTABILIDADE ESTRUTURAL DA β-LACTOGLOBULLNA EM SOLUÇÃO AQUOSA

En este trabajo se presenta un estudio sistemático sobre el efecto del incremento en el número de grupos OH de alcoholes y polioles de cuatro carbonos sobre las propiedades conformacionales de la β-lactoglobulina. Los cambios en el comportamiento de las soluciones acuosas de la proteína por la adición de 1-butanol, 1,2-butanodiol, 1,2,4-butano-triol y 1,2,3,4-butanotetrol fueron determinados por espectroscopia UV, de fluorescencia y DC en el UV lejano, y en el UV cercano a 298,15 K. Los resultados muestran que el butanol ejerce una mayor modificación en la estructura de la proteína y el efecto va disminuyendo a medida que se incrementa el número de grupos OH.

In this work we present a systematic study of the effect of the increase of OH groups in alcohols and polyols of four carbon atoms on the conformational properties of β-lactoglobulin. The changes in the behavior of the aqueous solution of the protein by the addition of 1-butanol, 1,2-butanediol, 1,2,4-butanetriol y 1,2,3,4-butano-tetrol were determined by UV, far and near UV CD spectra and fluorescence spectroscopy at 298.15K. The results show that the largest modification ofprotein structure is due to butanol and the effect decreases as the number of OH groups increase.

Neste trabalho apresenta-se um estudo sistemático sob o efeito do acréscimo do número de grupos OH de alcoóis e polióis de quatro carbonos nas propriedades conformacionais da β-lactoglobulina. As mudanças no comportamento das soluções aquosas da proteína, pela adição de 1-butanol, 1,2 butanodiol, 1,2,4 e 1,2,3,4 butanotetrol butanotriol, foram determinados por espectroscopia UV, fluorescência e DC no UV distante, e no UV próximo a 298,15 K. Os resultados mostraram que o butanol tem uma maior influencia na estrutura da proteína, e o seu efeito diminui com o aumento do número de grupos OH.

Identification of an important component of the contact sex pheromone of Callidiellum rufipenne (Coleoptera: Cerambycidae).

Adult male and female Callidiellum rufipenne (Motschulsky) (Coleoptera: Cerambycidae) aggregate on severely stressed or fallen trees and cut logs of cypress species (Cupressaceae) that are the hosts of their larvae. Our studies showed that male C. rufipenne actively search for females on these trees and only respond to females after contacting them with their antennae. Removing cuticular hydrocarbons from fresh carcasses of females with solvent rendered the carcasses unattractive to males, but activity was restored when the solvent extract was reapplied. These findings suggest that contact pheromones mediate mate recognition in this species. Bioassays of fractions of the extracts determined that the branched chain hydrocarbon fraction was primarily responsible for activity. 5,17-Dimethylnonacosane was a key sex-specific component in extracts of females, and synthetic 5,17-dimethylnonacosane elicited a strong mating response from males. We conclude that this compound is an important component of the contact sex pheromone of C. rufipenne if not the sole component. Solvent extracts of both sexes also contained 9-pentacosyne and 9-heptacosyne. To our knowledge, this is only the second report of alkynes in the cuticular lipids of insects.

ESTABILIZACIÓN DE HOLO-α-LACTOALBÚMINA EN PRESENCIA DE POLIOLES / HOLO-α-LACTALBUMLN STABILIZATION IN THE PRESENCE OF POLYOLS / ESTABILIDADE TÉRMICA DA HOLO-α-LACTOALBUMFNA EM PRESENÇA DE POLIÓIS

En este trabajo se presenta un estudio sistemático sobre el efecto de las soluciones acuosas de eritritol, xilitol, sorbitol e inositol con diferentes concentraciones, sobre la estabilidad térmica de la holo-α-lactoalbúmina bovina con pH 6,5 usando espectroscopia UV-VIS. Los resultados obtenidos muestran que los polioles usados estabilizan la holo-α-lactoalbúmina en un grado significativamente menor al reportado para otras proteínas. Se sugiere que este menor efecto de estabilización ocurre debido a que esta proteína presenta un estado desnaturalizado parcialmente desdoblado.

In this work we present a systematic study of the effect of aqueous solutions of erythritol, xylitol, sorbitol and inositol on thermal stability of bovine holo-α-lactalbumin at pH 6,5 using UV-VIS spectroscopy. The results show that the polyols used stabilize the holo-α-lactoalbumin in a significant lesser extent than the reported for others proteins. It is suggested that the lower stabilization achieved for this protein is the result of a partially unfolded denaturated state that this protein presents.

Neste trabalho é apresentado um estudo sistemático acerca do efeito de soluções aquosas de eritritol, xilitol, sorbitol e inositol a diferentes concentrações sobre a estabilidade térmica da holo-α-lactoalbumina bovina a pH 6,5 usando espectroscopia UV-VIS. Os resultados obtidos mostram que os polióis usados estabilizam a holo-α-lactoalbumina num grado significativamente menor ao reportado para outras proteínas. Se sugere que este menor efeito de estabilização ocorre devido a que esta proteína apresenta um estado desnaturalizado parcialmente desdobrado.

Efecto de la tepperatura sobre la viscosidad desoluciones acuosas diluidas de 1,2-hexanodiol, 1,5-hexanodiol, 1,6-hexanodiol y 2,5-hexanodiol / Effect of temperature on the viscosities of dilute aqueous solutions of 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol and 2,5-hexanedool / Efeito d temperaatura sobre as propriedades viscosimetrio de soluções aaquosas diluídas de 1,2-hexanodiol, 1,5-hexanodiol, 1,6-hexanodiol y 2,5-hexanodiol

Se determinó la viscosidad de soluciones acuosas diluidas de 1,2-hexanodiol, 1,5- hexanodiol, 1,6-hexanodiol y 2,5-hexanodiol en un rango de temperatura entre 283,15 y 308,15 K usando viscosímetros tipo Ubbelohde. Los valores de viscosidad relativa fueron ajustados a una ecuación de segundo orden para obtener el coeficiente B que está relacionado con el tamaño y la forma de la molécula de soluto. La dependencia del coeficiente B de viscosidad con la temperatura se discute en términos de la posición de los grupos hidroxilo en la estructura del agua.

Experimental viscosities of dilute aqueous solutions of 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol and 2,5-hexanediol were measured in the temperature range from 283,15 to 308,15 K using Ubbelohde viscometers. The relative viscosity values were adjusted by least-squares to a second order equation to obtain the viscosity B coefficient which has been related to the size and shape of the solute molecule. The temperature dependence of the viscosity B coefficient is discussed in terms of the effect of the position of the hydroxyl groups in the diol molecules on water structure.

Determinou-se a viscosidade de soluções aquosas diluídas de 1,2-hexanodiol, 1,5- hexanodiol, 1,6- hexanodiol y 2,5- hexanodiol numa faixa de temperatura entre 283,15 y 308,15 K, com o auxílio de viscosímetros tipo Ubbelohde. Os valores de viscosidade relativa foram ajustados a uma equação de segunda ordem para a obtenção do coeficiente B, que está relacionado com o tamanho e a forma da molécula de soluto. A dependência do coeficiente de viscosidade B com a temperatura é discutido em termos da posição dos grupos hidroxila na estrutura da água.

Efecto de la tepperatura sobre las propiedades olumétricas de alcoholes alifátticos en soluciones acuosas diluidas / Effect of temeraature on the volumetric propeties of aliphatic alcohols in ddilute aqueous solutinss / Efeito datemperaatura sobre as propriedades volumétrico d álcoois alifátticos em soluções aquosas diluídas

La influencia de la temperatura sobre las propiedades volumétricas de soluciones acuosas ha sido frecuentemente usada para obtener información sobre los efectos de los distintos solutos sobre la estructura del agua. En este trabajo se presentan los resultados experimentales de densidades de soluciones acuosas diluidas de n-pentanol, n-hexanol, n-heptanol y n-octanol a 288,15; 293,15; 298,15; 303,15 y 308,15 K. Las medidas de densidad fueron realizadas en un densímetro Antón Paar de tubo vibracional (DMA 60/602) y a partir de los datos obtenidos se calcularon volúmenes de exceso, volúmenes molares aparentes y volúmenes molares parciales a dilución infinita. Para determinar el carácter hidrofóbico de los solutos empleados y su efecto sobre la estructura del agua se empleó el criterio de la segunda derivada del volumen molar parcial en función de la temperatura. Se calculó la contribución volumétrica del grupo CH2 encontrándose que tiene un valor constante en el rango de temperatura estudiado.

The effect of temperature on the behavior of volumetric and surface properties of aqueous solutions has often been used to obtain information about solute effect on water structure. In this work, we present experimental results for densities of dilute aqueous solutions of n-pentanol, n-hexanol, n-heptanol and n-octanol at 288.15; 293.15; 298.15; 303.15 and 308.15 K. Density measurements were realized using an Anton Paar (DMA 60/602) vibrating tube densimeter. Excess volumes, apparent volumes and molar partial volumes at infinite dilution were evaluated from density data. The second derivate of partial molar volume with temperature was used to determine the hydrophobic character of the solutes and their effect on the water structure. The volumetric contribution of CH2 group was evaluated and it has a constant value at the studied temperatures.

A influência da temperatura sobre as propriedades volumétricas de soluções aquosas tem sido freqüentemente usada para obter informação sobre os efeitos dos diferentes solutos na estrutura do água. Neste trabalho apresentam-se os resultados experimentais de densidades de soluções aquosas diluídas de n-pentanol, n-hexanol, n-heptanol y n-octanol à 288,15; 293,15; 298,15; 303,15 y 308,15 K. As medidas de densidade foram realizadas num densímetro Anton Paar de tubo vibracional (DMA 60/602) e partindo dos dados obtidos calcularam-se volumes de excesso, volumes molares aparentes e volumes molares parciais à diluição infinita. Para determinar o caráter hidrofóbico dos solutos e o seu efeito sobre estrutura de água usou-se o critério da segunda derivada do volume molar parcial em função da temperatura. Foi calculado a contribuição volumétrica do grupo de CH2 encontrando- se que tem um valor constante na faixa de temperatura estudada.

Thermal stability of beta-lactoglobulin in the presence of aqueous solution of alcohols and polyols.

A systematic study concerning the effect of aqueous solution of alcohols and polyols with four carbon atoms on beta-lactoglobulin stability is presented. The protein was chosen due to its functional properties and applications in food and pharmaceutical industries and because its structure and properties in aqueous solution have been widely described. The alcohols having a four carbon chain were selected to examine the effect of the gradual increase in the number of OH groups on protein stability. Protein thermal stability in water, buffers and dilute aqueous solutions of 1-butanol, 1,2-butanediol, 1,2,4-butanetriol and 1,2,3,4-butanetetrol was evaluated by fluorescence spectroscopy. The results were used to determine the temperature range in which the unfolding process is reversible and the protein denaturation temperature in acetate buffer pH 5.5 and in the aqueous mixed solvents. Thermodynamic results show that alcohol denaturating effect diminishes gradually as the number of OH groups increase.

Construcción y aalibración de un equipo isopiésico para la determinación de cooeficientes osmóticos y coeficientes de actividad / Construction and calibration of n isopiestic apparatus for determination of osmmotic and activity coefficients

Se describe un equipo isopiéstico para la determinación de los coeficientes osmóticos de soluciones acuosas, usando cloruro de sodio como sustancia de referencia a temperaturas de 288,15 K, 293,15 K y 298,15 K. Los tiempos de equilibrio estuvieron entre 12 y 20 días para concentraciones de 0,1 a 0,6 m. Los coeficientes osmóticos de las soluciones acuosas de KCl obtenidos a partir del método isopiéstico y los coeficientes de actividad calculados fueron comparados con datos de literatura.

An isopiestic apparatus for determination of osmotic coefficients of aqueous solutions using NaCl reference solutions is described. Measurements were made at 288,15 K, 293,15 K and 298,15 K. Equilibrium times between 12 and 20 days were required for molalities between 0,1 and 0,6 m. Osmotic coefficients of aqueous KCl solutions obtained by the isopiestic method and calculated activity coefficients are compared with literature data.