Development and validation of a RP-HPLC method to determine the xanthyletin content in biodegradable polymeric nanoparticles

Xanthyletin is used as an inhibitor of the symbiotic fungus (Leucoagaricus gongylophorus) of the leaf-cutting ant (Atta sexdens rubropilosa), one of the most significant agricultural plague insects. The incorporation of this compound into nanoparticles is a promising approach to effectively control leaf-cutting ants. This study presents the development and validation of a specific analytical method using high-performance liquid chromatography (HPLC) for quantification of the xanthyletin content in biodegradable polymeric nanoparticles. The analytical methodology developed was specific, linear, accurate, precise, and robust. The absolute recovery of xanthyletin in colloidal suspensions was nearly 100%. The HPLC method proved reliable for the quantification of xanthyletin content in nanoparticle formulations.

Influence of initial CaO/SiO2 ratio on the hydration of rice husk ash-Ca(OH)2 and sugar cane bagasse ash-Ca(OH)2 pastes

This work presents the results of a study on the hydration of pastes containing calcium hydroxide and either rice husk ash (RHA) or sugar cane bagasse ash (SCBA) in various initial CaO/SiO2 molar ratios. The products of the reactions were characterized by thermal analyses X-ray diffraction, and scanning electron microscopy. In the case of the RHA pastes, the product was composed of CaO-SiO2-H2O (type I C-S-H) or CaO-SiO2-H2O (type II C-S-H) according to the CaO/SiO2 ratio of the mixture. In contrast, in the case of the SBCA pastes, the product was composed primarily of CaO-SiO2-H2O that differed from both the previous types; the product also contained inclusions of calcium aluminate hydrates.

DEVELOPMENT AND VALIDATION OF ANALYTICAL METHOD FOR PALM OIL DETERMINATION IN MICROCAPSULES PRODUCED BY COMPLEX COACERVATION

The microencapsulation of palm oil may be a mechanism for protecting and promoting the controlled release of its bioactive compounds. To optimize the microencapsulation process, it is necessary to accurately quantify the palm oil present both external and internal to the microcapsules. In this study, we developed and validated a spectrophotometric method to determine the microencapsulation efficiency of palm oil by complex coacervation. We used gelatin and gum arabic (1:1) as wall material in a 5% concentration (w/v) and palm oil in the same concentration. The coacervates were obtained at pH 4.0 ± 0.01, decanted for 24 h, frozen (−40 ºC), and lyophilized for 72 h. Morphological analyzes were then performed. We standardized the extraction of the external palm oil through five successive washes with an organic solvent. We then explored the best method for rupturing the microcapsules. After successive extractions with hexane, we determined the amount of palm oil contained in the microcapsules using a spectrophotometer. The proposed method was shown to be of low cost, fast, and easy to implement. In addition, in the validation step, we confirmed the method to be safe and reliable, as it proved to be specific, accurate, precise, and robust.

Development and validation of spectrophotometric method for the determination of DPP-4 inhibitor, sitagliptin, in its pharmaceutical preparations

A simple, sensitive and reproducible spectrophotometric method was developed for the determination of sitagliptin phosphate in bulk and in pharmaceutical formulations. The proposed method is based on condensation of the primary amino group of sitagliptin phosphate with acetyl acetone and formaldehyde producing a yellow colored product, which is measured spectrophotometrically at 430nm. The color was stable for about 1 hour. Beer's law is obeyed over a concentration range of 5-25 µg/ml. The apparent molar absorptivity and Sandell sensitivity values are 1.067 x 10(4) Lmol-1cm-1 and 0.0471 µgcm-2 respectively. All the variables were studied to optimize the reaction conditions. No interference was observed in the presence of common pharmaceutical excipients. The validity of the method was tested by analyzing sitagliptin phosphate in its pharmaceutical preparations. Good recoveries were obtained. The developed method was successfully employed for the determination of sitagliptin phosphate in various pharmaceutical preparations.

Development and validation of spectroscopic methods for simultaneous estimation and dissolution of ofloxacin and ornidazole in tablet dosage forms

The aim of this work was to develop and validate simple, accurate and precise spectroscopic methods (multicomponent, dual wavelength and simultaneous equations) for the simultaneous estimation and dissolution testing of ofloxacin and ornidazole tablet dosage forms. The medium of dissolution used was 900 ml of 0.01N HCl, using a paddle apparatus at a stirring rate of 50 rpm. The drug release was evaluated by developed and validated spectroscopic methods. Ofloxacin and ornidazole showed 293.4 and 319.6nm as λmax in 0.01N HCl. The methods were validated to meet requirements for a global regulatory filing. The validation included linearity, precision and accuracy. In addition, recovery studies and dissolution studies of three different tablets were compared and the results obtained show no significant difference among products.

Application and validation of a warning system for grapevine downy mildew controlusing fungicides

Most warning systems for plant disease control are based on Vinho, in Bento Gonçalves - RS, during the growing seasons 2000/ weather models dependent on the relationships between leaf wetness 01, 2002/03 and 2003/2004, using the grape cultivar Isabel. The duration and mean air temperature in this period considering the conventional system used by local growers was compared with the target disease intensity. For the development of a warning system to new warning system by using different cumulative daily disease severity control grapevine downy mildew, the equation generated by Lalancette values (CDDSV) as the criterion to schedule fungicide application and et al. (7) was used. This equation was employed to elaborate a critical reapplication. In experiments conducted in 2003/04, CDDSV of 12 - period table and program a computerized device, which records, though 14 showed promising to schedule the first spraying and the interval electronic sensors, leaf wetness duration, mean temperature in this between fungicide applications, reducing by 37.5% the number of period and automatically calculates the daily value of probability of applications and maintaining the same control efficiency in leaves infection occurrence. The system was validated at Embrapa Uva e and bunches, similarly to the conventional system.

Effects of different light levels on the initial growth and photosynthesis of Croton urucurana Baill. in southeastern Brazil

Four levels of shading (full sunlight (0%), 30, 50, 70% of solar radiation interception on growth, chlorophyll concentration and photosynthetic rate were studied in Croton urucurana Baill., a pioneer plant species. This species seedlings are of potential interest for reforestation projects and recovery of degraded areas. The seedlings were grown in pots containing soil and sand (2:1) and later transferred to plastic bags of 3 dm³ and submitted to different levels of shading (30, 50, 70%) of solar radiation and full sunlight, as control. The experimental design was completely randomized with five replicates and each experimental unit was composed of five plants. The results suggest that plants submitted to 70% shading showed higher dry weight accumulation in leaf and root, and higher plant height and leaf area. However, the seedlings root system showed higher dry biomass under full sunlight. It was observed a tendency to increase chlorophyll concentration and to decrease photosynthetic rate with the increase of the shading level.

Initial development and gas exchange of Talisia subalbens (Mart.) Radlk. under different shading conditions

Ecophysiological studies under semi-controlled conditions in nurseries and greenhouses are essential to enable the use of native species to recover degraded areas and for commercial planting. Talisia subalbens (Mart) Radlk, 'cascudo', is a native fruiting species of the Cerrado on the verge of extinction. The ecophysiological performance of this species was evaluated in nursery conditions under different levels of shading (full sunshine, 30%, 50% and 70%). Initial growth, biomass allocation, gas exchange and chlorophyll content of the plants were analyzed. Full sunshine cultivated plants showed a higher accumulation of total, shoot, and root dry biomass. There was no significant difference in the root/shoot ratio among the treatments. Seedlings cultivated under full sunshine and 30% shading showed higher values for height, basal diameter, and leaf area. Differences in stomata conductance and photosynthesis rate were not observed among the different shading levels. Plants cultivated under 70% of shading had higher contents of chlorophyll a, b, and total. During the initial phase with higher levels of radiation were fundamental for the development of T. subalbens seedlings.

Planting density and initial growth of two tree species adapted to the semi-arid region

Planting densities influence several aspects of forest formation, including management practices, timber yield, quality, and extraction, and consequently its production costs. The objective of this study was to evaluate Mimosa caesalpiinifolia and Gliricidia sepium growth as a function of planting density (400, 600, 800, 1000, and 1200 plants ha-1) and plant age. The species were evaluated every 90 days for plant height (PH), crown diameter (CD) and root collar diameter (RCD) (10 cm above the ground), with the first evaluation performed at 90 days and the last at 720 days. When plants were one year of age and beyond, evaluations were conducted also for stem diameter at breast height (DBH) (1.30 m above the ground). A randomized block design with split-plots and three replicates was adopted. Species were assigned to plots, planting densities were assigned to subplots, and evaluation ages were assigned to subsubplots. The four traits in both species had their values decreased as planting density increased, but continually increased as plant age increased. For PH and RCD there was an alternation between species superiority, with gliricidia being superior to sabiá at some ages, while the opposite occurred at other ages. As to CD the species only differed in the last measurement, gliricidia being superior. With regard to DBH, gliricidia was superior starting from the second measurement. There was an effect of the species × ages interaction for the four traits and also an effect of the densities × ages interaction for CD and DBH.

Initial growth of Bauhinia variegata trees under different colored shade nets and light conditions

Bauhinia variegata and B. variegata var. candida, commonly known as orchid trees, are small sized trees widely used for urban forestry and landscaping. Adult plants grow under full sun; in Brazil, however, seedlings are generally cultivated in commercial nurseries under natural half-shading. The objective of this study was to evaluate the influence of different colored shade nets and light conditions on the initial growth of B. variegata and B. variegata var. candida. The influence of six light conditions (red net with 50% shading; blue net with 50% shading; black net with 70% shading; black net with 50% shading; black net with 30% shading; and full sun) on the initial growth of B. variegata and B. variegata var. candida were evaluated along 160 days, and growth relationships were calculated. Seedlings showed more efficiency on the use of photoassimilated compounds when grown under full sun. Such condition is the most appropriate for seedling production of B. variegata and B. variegata var. candida, contradicting what has been performed in practice.

Anaerobic biodigestion of pigs feces in the initial, growing and finishing stages fed with diets formulated with corn or sorghum

The objective of this study was to evaluate the quality and the production of biogas and biofertilizer obtained from biodigester supplied with pig feces in the initial, growing and finishing stages, fed with diets formulated based on corn or sorghum. Twenty bench biodigesters were used with hydraulic retention time of 30 days and daily loads that contained 4 to 6% of total solids (TS) and 3.6 to 5.2% of volatile solids (VS). In the effluent of the biodigesters, mean levels of TS were observed ranging between 1.6 and 2.0% and of VS between 1.2 and 1.6%. The mean reductions of TS were 57.7 to 64.7% and of VS from 61.7 to 69.0%, and there was only difference in the finishing phase, in which the major averages reductions were produced by the biodigesters supplied with feces from animals fed with diets based on corn. In biodigesters supplied with feces from animals in the initial and growing stages fed with diets based on corn, were observed higher average productions of biogas and the greatest average potentials of biogas production. The average potentials obtained were 0.033; 0.181; 0.685; 0.788 and 1.132 m³ per kg of affluent, manure, TS added, VS added and VS reduced, respectively. No differences were found on the average content of methane in the biogas between diets and stages. The average concentrations of nutrients N, P, K, Ca, Mg, Na, Fe, Mn, Zn and Cu in the biodigester affluent and effluent, ranged between diets and stages.

Initial development of two eucalyptus hybrid submitted to irrigation

The eucalyptus offers several advantages compared to other forestry species and, by using the irrigation can increase productivity and decrease production time. The objective of the present study was to evaluate two hybrid eucalyptus (Grancam and Urograndis), no irrigation, dripping and micro sprinkler irrigated at 90, 120, 150 and 180 days after transplanting (DAT). The experiment was conducted at the experimental irrigation area in the State University of Mato Grosso do Sul, in the municipality of Aquidauna - State of MS, Brazil. The experimental design was randomized blocks, split plot with four blocks and two replications within each block, and the plots were composed by irrigation treatments (dripping, micro sprinkler irrigate and dry) and the subplots the hybrids (Grancam and Urograndis).The total area of the experiment had 3 hectares, where each plot consisted of 1 ha. It was evaluated plant height, stem diameter and canopy, stem basal area, the relationship between height and stem diameter, the relationship between height and canopy diameter and stem volume. Data were subjected to analysis of variance and compared by Tukey test at 5% probability. Irrigation systems and dripping sprinkle provide greater plant height, stem diameter, canopy diameter, stem basal area and stem volume.

Uncertainties of the 137Cs technique for validation of soil redistribution modelling in a semiarid meso-scale watershed

Scarcity of long-term series of sediment-related variables has led watershed managers to apply mathematical models to simulate sediment fluxes. Due to the high efforts for installation and maintenance of sedimentological gauges, tracers have been pointed out as an alternative to validate soil redistribution modelling. In this study, the 137Cs technique was used to assess the WASA-SED model performance at the Benguê watershed (933 km²), in the Brazilian semiarid. Qualitatively, good agreement was found among the 137Cs technique and the WASA-SED model results. Nonetheless, quantitatively great differences, up to two orders of magnitude, were found between the two methods. Among the uncertainties inherent to the 137Cs technique, definition of the reference inventory seems to be a major source of imprecision. In addition, estimations of water and sediment fluxes with mathematical models usually also present high uncertainty, contributing to the quantitative differences of the soil redistribution estimates with the two methods.

Validation study of an overall radiation balance estimation method under Ponta Grossa (PR) Brazil weather conditions

Radiation balance is the fraction of incident solar radiation upon earth surface which is available to be used in several natural processes, such as biological metabolism, water loss by vegetated surfaces, variation of temperature in farming systems and organic decomposition. The present study aimed to assess and validate the performance of two estimation models for Rn in Ponta Grossa city, Paraná State, Brazil. To this end, during the period of 04/01/2008 to 04/30/2011, from radiometric data collected by an automatic weather station set at the Experimental Station, of the State University of Ponta Grossa. We performed a linear regression study by confrontation between measurements made through radiometric balance and Rn estimates obtained from Brunt classical method, and the proposed method. Both models showed excellent performance and were confirmed by the statistical parameters applied. However, the alternative method has the advantage of requiring only global solar radiation values, temperature, and relative humidity.

Construction and validation of a surgical skills assessment tool for general surgery residency program

Objective: To develop and validate an instrument for measuring the acquisition of technical skills in conducting operations of increasing difficulty for use in General Surgery Residency (GSR) programs. Methods: we built a surgical skills assessment tool containing 11 operations in increasing levels of difficulty. For instrument validation we used the face validaity method. Through an electronic survey tool (Survey MonKey(r)) we sent a questionnaire to Full and Emeritus members of the Brazilian College of Surgeons - CBC - all bearers of the CBC Specialist Title. Results: Of the 307 questionnaires sent we received 100 responses. For the analysis of the data collected we used the Cronbach's alpha test. We observed that, in general, the overall alpha presented with values near or greater than 0.70, meaning good consistency to assess their points of interest. Conclusion: The evaluation instrument built was validated and can be used as a method of assessment of technical skill acquisition in the General Surgery Residency programs in Brazil.