FOOD ENERGY VALUES. EXAMPLE OF AN EXPERIMENTALDETERMINATION, USING COMBUSTION CALORIMETRY. The energies involved in the combustion, under atmosphere of oxygen, of breakfast cereals and dehydrate powdered whole milk samples, were determined by combustion calorimetry. This practical work, in the ield of human nutrition, involved the characterization of the nutritional composition and the combustion of samples of the two foods that are part of the alimentary diet, namely, at breakfast. The obtained results allowed to assess the energy value printed in the foods labels and discuss the way those values are estimated.
In this paper, firstly, a brief description of cavitation phenomena in Francis turbines is given. Then, based on the literature survey, cavitation detection and measurement methods are explained. The details of the mechanism used for the cavitation tests of the turbines are presented. Finally, model test procedures and determination of model dimensions according to similitude principles of model and the prototype are briefly described.
Test medium parameters recorded during the assay fulfilled all the requirements for acute toxicity tests with fish (16.2 ± 0,1°C, pH = 8.1 ± 0.1, oxygen concentration = 8.8 ± 0.3 mg.L -1 and oxygen saturation > 89.4%) and no mortality was recorded during the assay. No relevant differences in anatoxin-a concentrations in test media among different times were found at any of the tested concentrations because the percentage of decay recorded at 96 h, was less than 20% of the initial concentration (T0) in all the anatoxin-a treatments (Fig. 1). These results confirm that anatoxin-a is stable in water at least for 96 hours at the experimental conditions used here. This is also important since the stability of the concentrations of the test-substance during the test is a pre-requisite for the use of static conditions in assays for BCF determination (OECD, 1992; Kleinow et al., 2008). These findings also indicate that the steady state of anatoxin-a concentrations in the fish body was already attained at 24h of exposure.
Este artigo teve como objetivo apresentar algumas das metodologias empregadas na determinação da frequência natural das estruturas. Para tanto, escolheu-se como objeto de estudo uma viga biapoiada em concreto armado. O estudo da dinâmica das estruturas se justifica por existir uma grande preocupação com a ocorrência de vibrações excessivas, indesejáveis do ponto de vista estrutural, já que podem causar danos na estrutura devido ao alto valor dos esforços solicitantes provocados. Assim, para o conhecimento dos modos de vibração de uma viga biapoiada em concreto armado foi feita análise no programa ABAQUS®. Após análise, modelou-se em laboratório uma viga com mesmas propriedades e geometria para ensaio dos modos de vibração experimental com auxílio de um aparelho piezoeléctrico do tipo acelerômetro ADXL 345 para medição das acelerações instantâneas. Posteriormente as medições foi utilizado o MATLAB® para fazer a transformada de Fourier e encontrar as frequências naturais e só assim compará-las aos valores simulados numericamente pelo ABAQUS®. Os resultados desta pesquisa demonstraram-se satisfatórios, validando a análise com utilização de sensores do tipo acelerômetro e a modelagem numérica pelo ABAQUS® e que poderia ser aplicada para o estudo em estruturas mais complexas.
We measured the effective pressure coefficients for the seismic velocities and elastic moduli of Brazilian limestones and sandsto- nes. The results show that, even for unconsolidated rocks, there is a deviation of the effective pressure coefficient from unity that can lead to errors on porepressure prediction from seismic data and also on time-lapse studies. These striking results are the first obtained for Brazilian rocks. Nevertheless, more experimental in- vestigations with different rock and fluid types are needed in order to obtain a better understanding of the effective pressure coeffici- ents and its influences on pressure estimation from seismic data.
Amongst the chemokine signalling axes involved in cancer, chemokine CXCL12 acting on chemokine receptor CXCR4 is particularly significant since it orchestrates migration of cancer cells in a tissue-specific metastatic process. High CXCR4 tumour expression is associated with poor prognosis of lung, brain, CNS, blood and breast cancers. We have identified a new class of small molecule CXCR4 antagonists based on the use of computational modelling studies in concert with experimentaldetermination of in vitro activity against CXCL12-induced intracellular calcium mobilisation, proliferation and chemotaxis. Molecular modelling proved to be a useful tool in rationalising our observed potencies, as well as informing the direction of the synthetic efforts aimed at producing more potent compounds.
Abstract - The knowledge of the phase equilibrium is one of the most important factors to study the design of separation processes controlled by the equilibrium. Fatty acids are present in high concentration as by- products in vegetable oils but the equilibrium data involving these components is scarce. The objective of this work is the experimentaldetermination of the liquid-vapor equilibrium of five binary different systems formed by carbon dioxide and palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). The equilibrium experimental data was collected at 40, 60 and 80ºC at 60, 90 and 120 bar, at the extract and raffinate phases, using an experimental apparatus containing an extractor, a gas cylinder and pressure and temperature controllers. The data was modeled using the cubic equation of state of Peng-Robinson with the mixing rule of van der Waals with binary interaction parameters. The model was adequate to treat the experimental data at each temperature and at all the temperatures together. The best model that includes the van der Waals mixing rule with two parameters has maximum deviation of 17%. The distribution coefficients were also analyzed and it was concluded that the fractionation of the fatty acids is possible using supercritical carbon dioxide.
This work investigated a strategy as a quality control parameter (QC), using standard surrogate with physical and chemical characteristics different of the analytes of interest, to minimize the effect matrix in the determination of pesticides, by solid phase microextraction gas chromatography with flame ionization detector (SPME-GC-FID), in environmental aqueous matrices with different characteristics: river water, estuarine, seawater and weir water.
T HE motivation for this work is as follows: given the severity of recent Natural Disasters involving coupling between Earthquake Fault Slips and Tsunami generation, it has been borne in upon the authors that efforts should be directed, in general, to facilitate those systems, such as monitoring, predictive and warning systems , , , , that would serve to mitigate these dire scenarios. The problem, baldly stated, is as follows: we seek to automate the process of solving an Inverse Problem, in this case the restitution of Event Epicentre coordinates from Energy-onset Timings, in a reliable and rapid manner. The technique we have chosen to follow up is: the solution of the above Inverse Problem by the rapid and possible automatic determination of Epicentral Coordinates that uses a Software Architecture which is to trigger either or both of:
. Amberlite XAD-2 functionalized with dithizone was also applied for the determination of cadmium in seawater result- ing in a detection limit of 6.7 ng L −1 . The determination of cadmium from waste, tap and mineral waters has been studied using a SPE system with alumina modified with sodium dodecyl sulfate and 1-(2-pyridylazo)-2-naphthol. This system reached a detection limit for cadmium of 24.3 ng L −1 . Furthermore, it has been demonstrated that alumina has a great potential for solid-phase extraction because of its high versatility [16–19]. It can function as both a cation and an anion exchanger, depend- ing on the solution pH; under basic conditions it shows a high affinity for a wide range of cationic species while, under acidic conditions it exhibits a high affinity for anionic species .
For the determination of analytes in environmental matrices becomes generally required isolation, pre- concentration and possibly a cleaning step (clean- up) due to the complexity of the matrix. Among the applied extraction methods for the determination of nonylphenol in water are liquid-liquid extraction (LLE), the solid phase extraction (SPE) solid- phase micro extraction (SPME) and dispersive liquid-liquid micro extraction (DLLME). In solid matrices or sewage sludge extractors type soxhlet and extraction assisted by ultrasound, extraction accelerated solvent (ASE) and pressurized liquid extraction (PLE) are most widely used. Table II presents an overview of nonylphenol extraction methods, liquid and solid matrices described more recently.
Today and increasingly, the choice of analytical methods, reagents, materials and systems used in laboratories is essential in the application of new technology on the market, outside the walls of laboratories. The preference for less polluting, cheaper, scalable systems and accessible reagents are essential in the spread and exploitation of science. The scientific community should always evaluate the socio-economic impact of analytical decisions. The combination of theoretical and experimental techniques confirmed the formation of an inclusion complex between darunavir and -cyclodextrin by our research group. Complexation was obtained in purified water in proportion of 1:1. In theoretical studies, complex darunavir: -cyclodextrin formed showed increased solubility in about 600 times against the free drug.
fatty material presents in the creams (Experimental section, Procedures for determination of 8-MOP in topical creams sub-section); and a limpid fraction, ideal for luorescence measurements, was obtained. Thus, the limpid extract (water-alcohol fraction) obtained with the use of KCl to break the emulsion led to results that indicated that there were no potential interfering substances that could inluence in the luorescence signals of 8-MOP in their wavelengths of excitation and emission (305/495 nm). Recovery studies and Figure 6 corroborate this information.
propuseram um método de hidrólise enzimática para extração de lipídios totais da soja, utilizando diversas enzimas, uma vez que o óleo da parede celular muitas vezes não é adequadamente extraído com solventes. Comparando a saponificação direta da amostra com e sem aquecimento, no método da saponificação com aquecimento, apesar de serem utilizadas diferentes quantidades de amostras e reagentes, após a aplicação de calor, houve a formação de uma solução viscosa e densa nas amostras de ração, inviabilizando sua continuidade. Além disso, não houve solubilização total das amos- tras de ração. O método da saponificação direta da amostra sem aquecimento foi o que apresentou um cromatograma com menor número de interferentes e maior área do pico de colesterol, além de ser de fácil execução e utilizar menor quantidade de solvente. Este método foi, portanto, selecionado para a otimização através de planejamento experimental.
The use of hybrid trial yields (Ybf) was considered sufficient for model calibration. When the model was validated with independent data, the errors (absolute deviation) were below 15%, which is acceptable for studies of yield determination influenced by climate variability. The yield data used for calibration (Yw) represents an optimum management, thus it was related to above-average management of trials. The model does not consider any biotic stress, such as pests and diseases, which may occur in the hybrid trials. Thus, these constraints and all possible available information on crop development should be considered when using experimental data for calibrating the model. In this study, most simulated yields for calibration and validation were slightly higher than Ybf, indicating the differences between simulated and experimental yields. It is emphasized that more specific data on physiological maturity of cultivars instead of harvest date could provide more accurate results. The use of actual yields for estimating Yw and/or Yp is a common practice, and has been performed by many authors (ERNST et al., 2016; HALL et al., 2013; LOBELL; CASSMAN; FIELD, 2009; VAN ITTERSUM et al., 2013). The use of publicly available data is also acknowledged (GRASSINI et al., 2015), as it is related to dissemination of the proposed assessment method. However, it must be emphasized that a greater availability of trial data, comprising spatial variability within regions, would decrease the level of uncertainties on model calibration and evaluation (HALL et al., 2013).
For enzyme extraction, the gills were removed, dried with absorbent paper, and weighed in analytical balance. The membrane’s cells of the gills of P. vivipara were isolated for dosage of the Na + K + - ATPase and Mg ++ - ATPase activities (Bouef et al., 1978; Harache et al., 1980). Stages of the membrane isolation for determination of the ATPase activity: (1) Homogenization in the Ultra Turrax of 0.2 g of tissue in 0.5 ml of Tris buffer 5 mM, Sucrose solution 0.25 mM, EGTA (Ethylene- Glycol bis ( β aminoethylether) N-N’ Tetra-acetic Acid) 0.2 mM, pH 7.4. Time of homogenization 1.5 min per 7,000 rpm at 4 o C. (2) Centrifugation at 8,714 xg for 10 min and removed the supernatant. (3) Centrifugation at 61,000 xg for 45 min. (4) Ressuspension in 1.5 ml of homogenization buffer in the Potter and preparation of a gradient 1:1 with the Tris buffer 5 mM, Sucrose solution 1.4 M, EGTA 0.2 mM pH 7.4 and centrifugation at 61,000 xg for 45 min. (5) Remotion of the membrane fraction and dilution of 5 times with Tris-EGTA buffer 0.2 mM pH 7.4 and centrifugation at 61,000 xg for 45 min. (6) Ressuspension in 1.5 ml with imidazole buffer 25 mM, Sucrose 0.25 mM, EGTA 0.2 mM pH 7.4. (7) Evaluation of the ATPase activity.