14 resultados para Afinidades químicas

em Repositório da Produção Científica e Intelectual da Unicamp


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The ONIOM method was used to calculate the proton affinities (PA) of n-alkylamines (CnH2n+1NH2, n = 3 to 6, 8, 10, 12, 14, 16 and 18). The calculations were carried out at several levels (HF, MP2, B3LYP, QCISD(T), ...) using Pople basis sets and at the QCISD(T) level using basis sets developed by the generator coordinate method (GCM) and adapted to effective core potentials. PAs were also obtained through the GCM and high level methods, like ONIOM[QCISD(T)/6-31+G(2df,p):MP2/6-31G+G(d,p))//ONIOM[MP2/6-31+G(d,p):HF/6-31G]. The average error using the GCM, with respect to experimental data, was 3.4 kJ mol-1.

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Surfactin, a lipopeptide produced by strains of Bacillus subtilis, has been proved to be a suitable biosurfactant in several applications. For many years, it has been investigated mainly for oil recovery and environmental usage. Its chemical, technological and functional characteristics turn surfactin into an attractive compound for several utilizations. In this review we emphasize some aspects of surfactin as a new food ingredient and its potential pharmaceutical and health applications.

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Descriptors in multivariate image analysis applied to quantitative structure-activity relationship (MIA-QSAR) are pixels of bidimensional images of chemical structures (drawings), which were used to model the trichomonicidal activities of a series of benzimidazole derivatives. The MIA-QSAR model showed good predictive ability, with r², q² and r val. ext.² of 0.853, 0.519 and 0.778, respectively, which are comparable to the best values obtained by CoMFA e CoMSIA for the same series. A MIA-based analysis was also performed by using images of alphabetic letters with the corresponding numeric ordering as dependent variables, but no correlation was found, supporting that MIA-QSAR is not arbitrary.

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A trial was carried out to evaluate the chemical composition in the aerial part of lettuce, cv. 'Elisa', irrigated with wastewater treated with constructed wetland and source deposit water, grown on a Rhodic Hapludox Soil, using the irrigation systems sprinkle, subsurface drip and surface drip irrigation. The experiment was carried out from August 17th to October 3rd of 2001 and the chemical analyses of the lettuce were accomplished to 47 days after transplanting of the seedling. The aerial part of the lettuce was analyzed as for the levels of total nitrogen, nitrate, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, sodium, boron, cobalt and molybdenum. The sodium and the sulfur presented higher levels than the maximum suitable in the aerial part of the lettuce and the smallest level of magnesium, while other chemical elements analyzed were normal and appropriate considering the standard for well-nourished plants, not being influenced by the water type. The sodium was the chemical element that presented the highest levels in the aerial part of the lettuce in the treatments irrigated with wastewater, presenting significant difference in relationship to the treatments irrigated with source deposit water in the three irrigation systems. The use of the different irrigation systems by the application of wastewater treated with constructed wetland did not interfere in the levels of nutrients in the aerial part of the lettuce.

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Excessive and inadequate handling of fruits and vegetables provides high incidences of physical damage, consequently, post harvest losses. The main goal of this work was to evaluate the impact magnitude in persimmon packing lines, Rama Forte, and to determine, at the laboratory, its impact limits. For evaluating the critical points it was used an instrumented sphere of 76 mm of diameter (Technmark, Inc, Lansing, USA), which registered the impact magnitude in seven distinctive impact lines located in four packing houses. For determining physical damages, tests were carried out at the laboratory, where fruit drop was related to impact magnitude, physical damage incidence and fruit post harvest losses. At the packing lines, the values found varied from 21 to 87 G on the transfer points and the majority of registered impacts (over 94%) were down 50G. Drops from 20 cm caused an increase in weight losses after six days of storage at room temperature. Drops from 20 and 30 cm caused skin darkness (low L values), associated to a decrease in color intensity (chroma). Impact drop did not affect pulp fruit chemical features.

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During the taxonomic study of the Thelypteridaceae from southeastern Brazil was founded Thelypteris polypodioides (Raddi) C. F. Reed and Thelypteris villosa (Link) C. F. Reed, two rare and poorly known species. The taxonomic position of these species is uncertain. This study presents key, descriptions, illustrations, data on geographical distribution, and comments for both species, as well as comments on taxonomic affinity between the two species and Thelypteris subgenera.

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The taxonomy of the genus Heliotropium L. in Brazil was studied, revealing nine species and two varieties: H. amplexicaule Vahl, H. angiospermum Murray, H. curassavicum L., H. curassavicum var. argentinum I.M. Johnst., H. elongatum (Lehm.) I.M. Johnst., H. elongatum var. burchellii I.M. Johnst., H. indicum L., H. leiocarpum Morong, H. nicotianaefolium Poir., H. phylicoides Cham. and H. transalpinum Vell. Descriptions, illustrations, comments on relationships based on morphology and data on species distribution are presented.

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This paper considers Judith Kestenberg's approach to the psychic contextualization of human body movements, presenting: 1) the main movement categories identified by Kestenberg and their meanings; 2) the relations (affinities and shocks) within these movement patterns; 3) the relations between the initial preferences of a child for certain rhythms of movements and his/her movement patterns in adult life. The aim of this research was to present Kestenberg's studies, which offer a necessary knowledge to those willing to comprehend human body movement in a therapeutic context.

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Alterations in physical, chemical and functional characteristics of egg proteins occur during storage. These changes depend on the storage conditions, mainly duration, temperature and relative humidity. This study examined the fresh egg Haugh unit score and the storage egg Haugh unit score, at room temperature (25°C) and under refrigeration conditions (8°C), during 7, 14 and 21 days of storage. Haugh units and albumin height decreased considerably during storage at room temperature. At 8°C, there was no significant difference in the Haugh unit for different periods of storage, but their values were smaller as compared to fresh eggs. The weight of the eggs was not affected by both storage and temperature. For both temperatures, pH was positively correlated with Haugh units and negatively with the albumin height.

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The durability and postharvest quality of cut flowers are fundamental attributes in value along the production chain and in consumer satisfaction. The objective of this study was to evaluate the effect of chemical inhibitors of ethylene action on maintaining the postharvest quality of chrysanthemum stems (Chrysanthemum morifolium Ramat cv. Dragon). The experiment tested maintenance solutions with silver thiosulfate (STS) under five levels (distilled water, a 0.2 mM STS, the STS 0.2 mM + sucrose at 50 g L-1, STS at 0.4 mM; STS at 0.4 mM + sucrose at 50 g L-1), and date of sampling, for three levels (0, 3, 6 days). Three replications with two flower stems in each treatment were used in the experiment. Physical assessments were made: color, fresh mass and relative water content; chemical evaluations: reducing sugars and pigments, and qualitative assessments: turgidity, flower color, and number of buds, open flowers and partially open flowers. Treatment with 0.2 mM STS resulted in better maintenance of fresh mass of stems. The concentration of pigments and reducing sugar was higher in those treatments in which sucrose was associated. The color and relative water content were favored in treatments STS 0.2 mM and 0.4 mM. The concentration of 0.2 mM STS obtained the best results, prolonging the vase life the stems. The quality of these stems was higher, with the best assessments of water content, color and turgidity.

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The development and use of techniques that extend the life vase of the flowers, maintaining the quality of the product, is essential for reducing postharvest losses. The objective of this work was to evaluate different solutions for maintenance, associated or not to sucrose, in maintaining the postharvest quality of chrysanthemum stems. The treatments used distilled water, 8-HQC to 100 mg L-1, 8-HQC to 100 mg L-1 + sucrose 50 g L-1, 8-HQC to 200 mg L-1, 8-HQC to 200 mg L-1 + sucrose 50 g L-1. Physical assessments were made: color, fresh mass and relative water content; chemical evaluations: reducing sugars and pigments, and qualitative assessments: turgidity, color of the flowers, and number of buttons, open flowers and partially open flowers. The combination of 8-HQC 200 mg L-1 + sucrose 50 g L-1 was the best performance that made for maintaining the quality of flower stems, favoring the opening of buttons and turgidity of petals. Sucrose contributed to better maintenance of the reserve substances in the shaft, which had increased the flower vase life.

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One of the main objectives of applying edible coatings on fruits surface is to create a protective film to reduce weight loss due to evaporation and transpiration and also to decrease the risk of fruit rot caused by environmental contamination, in order to improve the visual aspect. Therefore, it is possible to increase shelf life, and decrease post harvest losses. Persimmon is a much appreciated fruit, with high potential for export, but sensitive to handling and storage. This study aimed to evaluate the effect of applying the edible coating Megh Wax ECF-124 (18% of active composts, consisting of emulsion of carnauba wax, anionic surfactant, preservative and water) produced by Megh Industry and Commerce Ltda in three different concentrations (25, 50 and 100%) on post harvest quality of 'Fuyu' persimmon stored for 14 days. The attributes evaluated for quality were: firmness, pH, acidity, soluble solids, weight loss and color. The results showed that application of carnauba wax in different concentrations was effective on decreasing weight loss of persimmon cv. Fuyu and maintenance of color aspects. Treatment at lower concentration, 25%, showed lower rate of discharge, but high concentrations showed lower values of mass loss. Carnauba wax application showed a high potential for use on postharvest conservation, and can be applied together with other technologies, helping to maintain quality for export.

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The association of 0,03 % v/w pectinase (Clarex), 0,6 % v/w invertase (Invertase-S) and 0,5 % w/w glucose isomerase (Taka-sweet) in industrialized banana (Musa cavendishii) pulp, under conditions of hydrolysis 40oC, 15 minutes, was observed and compared to other three enzymatic treatements: 0,03 % v/w pectinase (Clarex); 0,03 % v/w pectinase (Clarex) associated to 0,6 % v/w invertase (Invertase-S); and 0,03 % v/w pectinase (Sigma) associated to 0,03 % cellulase (Sigma) to determine the quality using a group of physical, physico-chemical, chemical, microbiological and sensory properties of the banana juices obtained. These properties had not differ significantly in function of pectinases and celulase employed. The addition of invertase had increased sweetness and decreased viscosity in juice. On the other side, the addition of glucose isomerase in inverted juice was not able in increasing significantly fructose content.

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Universidade Estadual de Campinas . Faculdade de Educação Física