Calorimetric study of the effect of water quantity on tetramethoxysilane hydrolysis under ultrasound stimulation

The ultrasound stimulated and oxalic acid-catalyzed hydrolysis of tetramethoxysilane (TMOS) was studied by means of a heat flux calorimetric method as a function of the initial water/TMOS molar ratio (r) ranging from 2 to 10. The method is based on the time recording of the hydrolysis exothermic heat peak. which takes place in acidulated heterogeneous water-TMOS mixtures under ultrasonic stimulation, accounting for the instantaneous hydrolysis rate. The hydrolysis rate increases from zero up to a maximum value during the heterogeneous step of the process and then diminishes naturally according to the reactant consumption. The total hydrolyzed quantity was found to be slightly increasing with r. The immiscibility gap of the TMOS- water system in the presence of the hydrolysis products has been inferred from the evaluation of the reacted quantity during the heterogeneous step of the reaction and it has been represented in a ternary diagram in the studied r-range.

Effects of the water quantity on the solventless TEOS hydrolysis under ultrasound stimulation

The acid hydrolysis under ultrasound stimulation of solventless tetraethoxysilane(TEOS)-water mixtures was studied at 40 degrees C, by means of a heat flux calorimetric method, as a function of the initial water/TEOS molar ratio (r) ranging from 2 to 10. The method is based on the time record of the exothermic heat peak of hydrolysis, arising after an induction time under ultrasound stimulation, which is a measure of the reaction rate. The hydrolysed quantity was found to be approximately independent of the water/TEOS molar ratio, even for r < 4. Polycondensation reaction takes place mainly for low water/TEOS molar ratio in order to supply water to allow almost complete hydrolysis. The overall process of dissolution and hydrolysis has reasonably been described by a previous modelling. The dissolution process of water in TEOS, under ultrasound stimulation and acid conditions, was found to be rather dependent of the alcohol produced in the hydrolysis reaction instead of the initial water quantity present in the mixture.

OPTIMIZATION OF EXTRUSION COOKING PROCESS FOR CHICKPEA (CICER-ARIETINUM, L) DEFATTED FLOUR BY RESPONSE-SURFACE METHODOLOGY

Response surface methodology was employed to optimize the production of a snack food from chickpea. The independent variables, process temperature (123-137-degrees-C) and feed moisture (13-27% d.s.b.) were selected at five levels (rotatable five level composite design: - square-root 2, -1, 0, 1, + square-root 2) in the extrusion of defatted chickpea flour. Response variables were expansion ratio, shear strength of the extrudate and sensory preference assessed by an untrained panel. Expansion ratio increased steadily with decrease in feed moisture similar to cereal extrusion. Regions of maxima were observed for sensory preference and shear strength, and these two product attributes were linearly related. The most acceptable chickpea snack was rated higher than a commercial corn snack.

THE CASSAVA (MANIHOT-ESCULENTA, C) CV PIONEIRA .3. COOKING CHARACTERISTICS

The edible parts of cassava cultivar Pioneira roots after 12 and 24 months of cultivation were analysed for human consum. The yield was 63% when the roots were harvested at the right time (12 months), and lower (58%) for older roots, with 24 months. Total cyanide contents were 62,0 - 61,8 and 58,0 - 63,4 ppm, respectively. Cooking time was 13,5 min and 19,5 min, respectively, although the cooked mass quality was similar good. The edible part of the roots was processed in french fries or tholes, submited to two treatment: blanching for three minutes and boiling for ten minutes. Treated and in natura tholes were fried in vegetable oil at 190-degrees-C. The effect of freezing (-20-degrees-C for 60 days) on the cooking quality was also evaluated. The frozen storage reduced the total cyanid content in all treatment. The rate of cyanid decrease were 45%, 84% and 88% with frying, blanching and frying, and boiling and frying, respectively. Blanching followed by frying assured a safe cyanid level for human consum as well as a good acceptance in sensorial analysis. The influence of the age of the roots in cooking quality was a decrease in softness. Frozen storage softened the 24 month old roots and worsened the flavor of 12 month old root. For table purposes cassava roots should be processed in french fries and blanching, what would allow frozen storage of edible part.

Carcass and meat quality traits of wild boar (Sus scrofa s. L.) with 2n=36 karyotype compared to those of phenotypically similar crossbreeds (2n=37 and 2n=38) raised under same farming conditions. 1. Carcass quantity and meat dressing

The aim of this study was to compare wild boar (chromosomal number 2n = 36) to phenotypically similar animals of 2n = 37 and 2n = 38 chromosomes (crossbreeds) with respect to live weight, carcass yield, meat yield, fat and weight of inner organs. All animals were born and raised on the same farm and slaughtered at 39 weeks. The final live weight of wild boar 2n = 36 was significantly lower (47.2 kg) as compared to crossbreeds (80.0 kg). Animals 2n = 36 had more carcass yields (65.5%) than 2n = 37 karyotype (64.9%) and 2n = 38 (64.4%). Wild boar had the highest yields for the cuts with bones and boneless cuts compared to crossbreeds. Therefore, variations in karyotype are accompanied by differences in some carcass quantitative traits, i.e., 2n = 36 grow and fatten slower than crossbreeds 2n = 37 and 2n = 38. (c) 2008 Elsevier Ltd. All rights reserved.

The minimum quantity of lubricant (MQL) technique in the surface grinding of steel

This research aimed to analyze the viability of the minimum quantity of lubricant (MQL) technique towards different methods of lubri-refrigeration in surface grinding of steel, considering process quality, wheel life and the viability of using cutting fluids The proposal methods were the conventional (abundant fluid flow), the minimum quantity lubrication (MQL) and the optimized method with Webster nozzle (rounded) This analysis was carried out in equal machining conditions, through the assessment of variables such as grinding force, surface roughness, G ratio (volume of removed material/volume of wheel wear), and microhardness The results showed the possibility of improvement of the grinding process Besides, there is the opportunity for production of high quality workpieces with lower costs The MQL technique showed efficiency in machining with lower depths of cut The optimized method with Webster nozzle applies the fluid in a rational way, without considerable waste Hence, the results show that industry can rationalize and optimize the application of cutting fluids, avoiding inappropriate disposal, inadequate use and consequently environment pollution

Study on the behavior of the Minimum quantity lubricant - MQL technique under different lubricating and cooling conditions when grinding ABNT 4340 steel

The behavior of the minimum quantity lubricant (MQL) technique was analyzed under different lubricating and cooling conditions when grinding ABNT 4340 steel. The comparative analysis of the residual stress values showed that residual compressive stresses were obtained under all the lubrication/cooling conditions and types of abrasive tools employed. The highest residual compressive stress obtained with the aluminum oxide grinding wheel with MQL under the condition of V= 30m/s for air and V= 40ml/h for lubricant was -376MPa against the -160MPa attained with conventional cooling, representing a 135% increase in residual compressive stress. The results show that method and quantity of lubricant and cooling are factors that influence the grinding process.

Influence of optimized lubrication-cooling and minimum quantity lubrication on the cutting forces, on the geometric quality of the surfaces and on the micro-structural integrity of hardened steel parts

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

Bioactive substance contents and antioxidant capacity of the lipid fraction of Annona crassiflora Mart. seeds

Annona crassiflora Mart. is a typical fruit of the Brazilian cerrado, considered to be a species of economic interest, mainly for its use in cooking, which is widespread among the inhabitants of that region, and can be found in many typical local dishes, especially sweets, jellies, liqueurs, soft drinks, ice creams and juices. Thus, the objective of this study was to determine the bioactive substance contents and the antioxidant capacity of the lipid fraction of A. crassiflora Mart. seeds in the interest of better identifying the quality of this raw material from the Brazilian cerrado. After the receipt of the fruits, the seeds were removed manually and, then, the lipid fraction was obtained by cold extraction with chloroform:methanol:water (2:1:0.8, v/v/v) and analyzed for the composition of phytosterols, tocopherols, fatty acids, total carotenoids, antioxidant activity and oxidative stability index. The lipid fraction showed significant quantity of bioactive substances, especially phytosterols, tocopherols and unsaturated fatty acids, as well as significant antioxidant capacity and oxidative stability, influenced by the content of phytosterols and the composition of fatty acids present in the analyzed fraction. © 2012 Elsevier B.V.

Inclusão de grãos de girassol na ração de cordeiros sobre as características quantitativas da carcaça e qualitativas da carne

This study aimed to evaluate the carcass quantitative characteristics, tissue composition of carcass cuts and meat quality of lambs receiving sunflower seeds in the diet. Twenty-one lambs 7/8 Ile de France 1/8 Ideal, not castrated, with initial body weight of 17 kg were housed in individual pens and distributed in three diets (0,7.5 and 15% of sunflower seeds inclusion) in a completely randomized design in 3 x 2 factorial arrangement (three diets and two carcass cuts). At the end of the experimental period, the animals were slaughtered; weights and hot and cold carcass yields and commercial and biological carcass dressing were collected. The carcasses were split lengthways and left half carcass divided into six anatomical parts. The leg and loin were removed for evaluation of tissue composition, meat color, water holding capacity, cooking losses and shearing force. Difference was detected in the commercial carcass yield; with higher value (46.82% of total weight) for carcasses of lambs fed without sunflower seeds when compared with carcass yield (44.11%) of lambs fed with 15% of sunflower seed inclusion. The proportion of muscle and total fat, as muscle:fat ratio were affected (P<0.05) by feeding, with higher quantity of muscle (63.15%) and less fat (16.63%) in the leg and loin cuts of lambs fed without sunflower seeds. In the leg was observed higher proportions of muscle (67.27%), muscle:bone ratio (4.08) and muscle:fat ratio (4.92) when compared with the loin cut. The water retention capacity and shearing force of Longissimus lumborum muscle showed better results when compared with Semimembranosus muscle. The inclusion of sunflower seeds in the diet of feedlot lambs increased the fat deposition in carcass cuts, however did not affect the other parameters of meat quality.