Synthesis of Water-Soluble Calixarenes Catalyzed One-Pot Mannich-Type Reaction in Aqueous Media

This article demonstrates the synthesis of new water soluble calix[4]arenes (8) based catalyst and application in one-pot, three component Mannich reactions to catalyze reaction between aromatic ketones/aldehyde and amines to acquire β-Amino carbonyl compounds in appreciable yields at room temperature in aqueous media.     

Biegeschwingungen der schnellrotierenden Kreiszylinderschale aus orthotropen Werkstoffen

Zusammenfassung Es wird ein Verfahren zur n?herungsweisen Berechnung der Biegeeigenfrequenzen schnellrotierender Kreiszylinderschalen aus orthotropen Werkstoffen vorgeschlagen. Im Gegensatz zur ruhenden Kreizylinderschale herrschen in der rotierenden Schale Umfangsspannungen. Diese Umfangsspannungen führen zu einer “Versteifung” der Schale und damit bei bestimmten Eigenformen zu einer Erh?hung der Biegeeigenfrequenz. Die N?herung besteht darin, da? man für den Fall der Biegeschwingung eine konstante Umfangsspannung annimmt. Dadurch wird das Gleichungssystem für einige technisch bedeutsame F?lle l?sbar.     

Effects of nitrite levels,endpoint temperature and storage on pink color development in turkey rolls

The objective of this research was to determine the relationship between minimum nitrite level, endpoint temperature and storage period on pink discoloration of turkey rolls. Rolls were prepared with 0, 3 or 5 parts per million (ppm) NO₂^–, cooked to an endpoint temperature of 75 °C or 85 °C and stored at 4 °C. During the 13-day storage period, on the 0th, 4th, 8th and 13th days cured pigment, total pigment, residual nitrite and color parameters were measured and sensory color was evaluated. At each endpoint temperature, addition of 3 ppm or 5 ppm NO₂^– significantly increased cured pigment and total pigment levels. Cured pigment levels of turkey rolls cooked to 75 °C were higher than rolls cooked to 85 °C, regardless of the NO₂^– level. There was a significant decrease in cured pigment levels at the end of the storage period (13th day). Analysis of residual NO₂^– in all treatment groups showed no detectable amounts. Endpoint temperature and addition of NO₂^– affected L* values: rolls cooked to the 75 °C endpoint had higher L* values. The additon of nitrite with the 75 °C endpoint temperature resulted in higher a* values. a* values also increased during the storage. The higher endpoint temperature (85 °C) resulted in lower a* values. Yellowness was not affected by final cooking temperature. Both the addition of NO₂^– and storage decreased b* values. The panel found no differences in pinkness intensity between the two levels of added nitrite (3 and 5 ppm). Sensory pinkness intensity in nitrite-added samples increased with increasing storage.     

Numerical determination of yield surfaces of Al/SiC laminated composite plates

In this study the elastic-plastic properties of an aluminum alloy reinforced by unidirectional SiC-fibers are computed by using nonlinear finite element simulations. In order to carry out these computations, a representative volume element assuming a regular quadratic arrangement of the fibers is used. The plastic properties of the composite are described by a quadratic flow criterion which is able to consider both direction and tension-compression anisotropy. Additionally, the flow rule takes into account plastic volume changes. The hardening of the material is defined by a mixed isotropic-kinematic hardening model. By using this modeling yield surfaces of multi-layer laminated composite plates under an in-plane loading are determined.