Effect of high-intensity ultrasonic field on process of semi-continuous casting for AZ80 magnesium alloy billets
TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA
Authors: Zhang Zhi-qiang; Le Qi-chi; Cui Jian-zhong
Abstract
Under the high-intensity ultrasonic field, AZ80 magnesium alloy was semi-continuously cast. The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated. The results show that the microstructures of the alloy cast under high-intensity ultrasonic field are fine and uniform, and the grains are equiaxed, rose-shaped or globular with an average size of 257 mu m. High-intensity field significantly decreases the grain size, changes the morphologies of the beta-Mg17Al12 phases and reduces their area fraction. It is also shown that a proper increase in ultrasonic intensity is helpful to obtain fine, uniform and equiaxed as-cast microstructures. The optimum ultrasonic parameters are that frequency is 20 kHz and ultrasonic intensity is 1 368 W. The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy billets cast under ultrasonic field are greatly improved, and with increasing the ultrasonic intensity, the mechanical properties of the entire alloy billets are much higher and more uniform than those of the alloy without ultrasonic field.
Nutritional potential of leaves and tubers of crem (Tropaeolum pentaphyllum Lam.)
REVISTA DE NUTRICAO-BRAZILIAN JOURNAL OF NUTRITION
Authors: Braga, Vanessa Bernardi; Vieira, Meite de Moraes; Inchausti de Barros, Ingrid Bergman
Abstract
Objective To determine the centesimal composition of minerals, fatty acids and vitamin C of leaves and tubers of crem, and to discuss the nutritional potential of the T. pentaphyllum species. Methods The centesimal composition of protein, lipid, fiber, ash and carbohydrate was determined by gravimetric analysis. Mineral composition was determined by optical emission spectrometry. Vitamin C was determined by dinitrophenylhydrazine method. Fatty acids were determined by gas chromatography. The percentage of recommended dietary intake of leaves and tubers of crem was calculated for each nutrient. Results A high content of fibrous fraction (63.07g/100g), potassium (4.55g/100g), magnesium (553.64mg/100g) and sulfur (480.79mg/100g) was observed in the chemical composition of leaves. In tubers, a high carbohydrate content was observed, with 62.60g/100g of starch and 3.43g/100g of fiber, as well as high potassium (0.58g/100g), sulfur (447.14g/100), calcium (205.54g/100g) and phosphorus (530.07g/100g) levels. The vitamin C content of tubers was 78.43mg/100g and the linoleic acid content was 0.455g/100g. The intake of 100g of crem leaves may contribute with 65% of the recommended dietary intake of sulfur. The intake of 100g of crem tuber may contribute with 106% of the recommended dietary intake of sulfur and 21% of the recommended dietary intake of Vitamin C. Conclusion The chemical composition of crem (Tropaeolum pentaphyllum Lam.) tubers and leaves demonstrated an important contribution of nutrients, mainly sulfur, vitamin C and linoleic acid in its tubers, indicating a high nutritional potential of this species.