Effect of pectinolitic enzymes on the physical properties of caja-manga (Spondias cytherea Sonn.) pulp

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Measurement of fats, oil and grease by spectro-photometry and its application on different sites at São Paulo State, Brazil

This investigation was carried out within the Parana sedimentary basin, Brazil, involved the sampling of effluents and groundwater from monitoring stations situated at different sites at São Paulo State, and was realized with the purpose of evaluating the presence of fats, oil and grease (FOG) in different matrices. Several tests were realized with very distinct materials (cooking oil, butter, margarine, pig fat, vacuum pump oil) in order to properly calibrate the spectrophotometric system. Each matrix was dissolved with 1,1,1-trichloroethane and from the stock solutions it was prepared working standards from different dilutions. The data obtained were plotted on absorbance vs. concentration graph that yielded a successful calibration curve when a mineral oil for vacuum pump was utilized in the experiments at a wavelength corresponding to 410 mn. The results obtained for the analyzed samples were compared with the limiting value established by the São Paulo State legislation on the prevention and pollution control of the environment that was established in 8(th) September 1976 by Rule No. 8468.

Spectroscopic studies on glassy Ni(II) and Co(II) polyphosphate coacervates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Amorphous manganese polyphosphates: preparation, characterization and incorporation of azo dyes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Changes of physical properties of glass surfaces exposed to KNO3 vapors

Modifications of glass surfaces were studied after exposure of samples to an atmosphere resulting from the decomposition of molten KNO3. The diffusion coefficient of K+ ions migrating into the surfaces of float glass and synthesized glasses doped with up to 5 wt% SnO2 was calculated by the Boltzmann-Matano technique. The Vickers hardness and the refractive index increase with exposure time. Infrared spectra show that the migration of K+ is responsible for an increase in the number of non-bridging oxygens in the exposed samples. The spectra of the synthesized glasses present evidences that their surfaces undergo crystallization during the exposure. All results lead to the conclusion that the presence of tin in the glasses hinders the diffusion of K+ ions, thus affecting the Vickers hardness, the refractive index and the infrared spectra. It is shown that the exposure method can be used as an alternative process to promote the K+ migration into glass surfaces. (c) 2006 Elsevier B.V. All rights reserved.

Mechanical properties, hydrophilicity and water activity of starch-gum film: effect of additives and deacetylated xanthan gum

The effect of deacetylated xanthan gum, additives (sucrose, soybean oil, sodium phosphate and propylene glycol) and pH modifications on mechanical properties, hydrophilicity and water activity of cassava starch-xanthan gum films has been studied. Sucrose addition resulted in the highest effect observed on cassava starch films elongation at break. The deacetylated xanthan gum had higher effect on elongation at break when comparing to the acetylated gum, although both gums presented an inferior effect in relation to the obtained with sucrose. However, when comparing to the control and PVC films, lower tensile strength resistance values were observed when adding sucrose. Increased water activity was observed for films added with sucrose, thus, increasing the material biodegradation. Sucrose and deacetylated xanthan gum addition resulted in a slight hydrophilicity increase. (C) 2004 Elsevier Ltd. All rights reserved.

Effect of chemical pretreatment on the physical properties of dehydrated grapes

The effects of chemical pretreatment and air drying temperature on drying kinetics, shrinkage, density and rehydration ratio of grapes were determined at various moisture contents. It was observed that the chemical pretreatment employed - a solution of 2% CaCO3 with 0 to 3% ethyl oleate - increased considerably the drying rate. It was established that the shrinkage increased with drying temperature between 40 to 80 degrees C and decreased with increasing concentration of ethyl oleate in the chemical pretreatment solution.

Physical properties of silicate glasses doped with SnO2

The presence of tin in the network of silicate glasses produces changes in several of their physico-chemical properties. Glasses with the composition (mol%) 22Na(2)O (.) 8CaO (.) 70SiO(2) containing up to 5 wt% of SnO2 were analyzed under several experimental techniques. Dilatometric measurements showed an increase of the glass transition temperature with increasing tin content, while the average thermal expansion coefficient is reduced. Vickers microhardness, density, and refractive index also increase with the tin content. Diffuse reflectance spectra in the infrared (DRIFT) showed that the presence of tin, even at low concentrations, is responsible for some structural changes since there is an increase of the bridging oxygen concentration. The doped glasses present a brown color and optical absorption spectra measurements are interpreted as being due to precipitation of tin in the form of colloidal particles during cooling of the melted glass. In the Na+ <-> K+ ion exchange process the presence of tin in the glass network hinders the diffusion of these ions. The diffusion coefficients of those ions were calculated by the Boltzmann-Matano technique, after concentration profiles obtained by EDS measurements. All results obtained present evidences that Sn4+ cation acts as a glass network former. (c) 2005 Elsevier B.V. All rights reserved.

The characteristics of a test liquid formulation for use in evaluating the performance of handling and metering systems

Injection metering systems are an important option for the development of pesticide application equipment, with advantages relating to minimising the need for disposal of unused pesticide, improving the ease of cleaning and optimising the accuracy of chemical application. For all injection systems, characteristics such as the steady-state accuracy of delivered dose, dose stability and the time response for dose step changes are related to the ability of the system to operate with different chemical formulations. A system designed to inject liquids should be able to accommodate changes in viscosity and density. The aim of this study was to develop a methodology for testing chemical injection systems using liquids with different viscosities. The experimental arrangement simulating applications with injection metering systems used dye and salt solutions as tracers. Tests were conducted to analyse the influence of salt on the characteristics of the water and a viscous solution. Results showed that the salt interfered with the dye stability in the water solution. In tests with a viscous test liquid, the salt was introduced at different steps during the mixing process, providing four different liquids to be analysed in terms of viscosity, density and pH. Some differences in liquid characteristics were found which could influence the performance of the injection systems.

Electronic structure of Pb1-xLaxTiO3 ferroelectric materials from Ti 2p and O 1s soft x-ray absorption spectroscopy

The electronic structure of Pb1-xLaxTiO3 (PLT) compounds for x ranging from 0 to 30 at. % of La is investigated by means of soft x-ray absorption near edge structure (XANES) at the Ti L-3,L-2 and O K edges. The greatest modification in the structure of the Ti 2p XANES spectra of the PLT compounds is observed in the region of the high energy peak of the L-3 edge (e(g) states), which exhibits a splitting in the undoped sample. As the amount of lanthanum increases, this splitting becomes less pronounced. This modification is interpreted as a decrease in the degree of disorder of titanium atoms, which is correlated to the substitution of Pb by La atoms. The structural changes observed at the low energy peaks of the O K-edge XANES spectra of the PLT compounds may be interpreted in terms of hybridization between O 2p, Ti 3d, and Pb 6p orbitals. A decrease in the degree of hybridization observed as Pb atoms are replaced by La atoms may be related to the differences in the ferroelectric properties observed between x=0.0 and x=0.30 compounds. (c) 2006 American Institute of Physics.

Thermo-physical properties of cooked ham

Experimental studies were carried out to determine thermal conductivity (k), thermal diffusivity (alpha), specific heat at constant pressure (c(p)), and density (rho) of cooked ham as functions of both sample moisture content (M) and temperature (T). Thermal conductivity was measured using the heat-line-source probe, thermal diffusivity by Dickerson method, specific heat by differential scanning calorimeter, and density by pycnometer assembly. Temperature ranged from 3.0 degrees C to 74.0 degrees C, corresponding to the cooking process, and moisture ranged from 40.0 to 73.0% (w. b.). Equations are provided for alpha as a function of M, c(p) as a function of T, and rho as a function of both M and T. Results for thermal conductivity are compatible with those published in the literature.

A generalized theory of electrical characteristics of schottky barriers for amorphous materials

In the present paper, we discuss a generalized theory of electrical characteristics for amorphous semiconductor (or insulator) Schottky barriers, considering: (i) surface states, (ii) doping impurity states at a single energy level and (iii) energetically distributed bulk impurity states. We also consider a thin oxide layer (≈10 Å) between metal and semiconductor. We develop current versus applied potential characteristics considering the variation of the Fermi level very close to contact inside the semiconductor and decrease in barrier height due to the image force effect as well as potential fall on the oxide layer. Finally, we discuss the importance of each parameter, i.e. surface states, distributed impurity states, doping impurity states, thickness of oxide layer etc. on the log I versus applied potential characteristics. The present theory is also applicable for intimate contact, i.e. metal-semiconductor contact, crystalline material structures or for Schottky barriers in insulators or polymers.

Effect of drying technique on some physical properties of cross-linked high amylose/pectin mixtures

Polymers mixtures as well as cross-linking reactions are approaches that have been used successfully to modulate the polymers characteristics in order to improve the control over drug release rate. High amylose and pectin are polysaccharides frequently used to prepare drug delivery systems. Since the drying technique can strongly influence the properties of such systems, the aim of this work was to characterize high amylose/pectin mixtures cross-linked with sodium trimetaphosphate and dried by different techniques-oven and lyophilization. The results showed that samples dried by lyophilization presented reduced particle size, higher porosity and higher swelling ability than the samples dried in oven. Besides, lower thermal stability and different diffraction patterns showed by the former particles should reflect the structural changes as a function of drying technique. © 2013 Informa Healthcare USA, Inc.

Soil organic matter and physical attributes affected by crop rotation under no-till

Growing cover crops in systems under no tillage affects different pools of soil organic matter, and eventually soil physical attributes are modified. The objective of this study was to evaluate changes in soil organic matter and their relationship with soil physical attributes as affected by plant species grown in rotation with soybean [Glycine max (L.) Merr.] under no-till for 3 yr. Crop rotations included grain sorghum [Sorghum bicolor (L.) Moench], ruzigrass [Urochloa ruziziensis (R. Germ, and CM. Evard) Crins] and sorghum mixed with ruzigrass, all grown in fall/winter, followed by pearl millet [Pennisetum americanum (L.) Leeke], sunn hemp (Crotalaria juncea L.) and sorghum-sudangrass [S. bicolor × S. sudanense (Piper) Stapf] grown during the spring, plus a fallow check plot. Soybean was grown as the summer crop. Millet and sorghum-sudangrass cropped in spring showed higher root and shoot production as spring cropping. In fall/winter, sorghum mixed with ruzigrass yielded higher phytomass compared with sole cropping. Soil physical attributes and organic matter fractioning were positively affected by cropping millet and sorghum-sudangrass whereas intermediate effects were observed after sunn hemp. Maintaining fallow in spring had negative effects on soil organic matter and physical properties. Ruzigrass and sorghum mixed with ruzigrass cropped in fall/winter resulted in better soil quality. Spring cover crops were more efficient in changing soil bulk density, porosity, and aggregates down to 0 to 10 cm; on the other hand, fall/winter cropping showed significant effects on bulk density in the uppermost soil layer. Total C levels in soil were increased after a 3-yr rotation period due to poor initial physical conditions. Fractions of particulate organic C, microbial C, and C in macroaggregates were the most affected by crop rotations, and showed high relation with improved soil physical attributes (porosity, density, and aggregates larger than 2 mm). © Soil Science Society of America, All rights reserved.