Thermodynamic Properties of Gases from Speed-of-Sound Measurements

A procedure for deriving thermodynamic properties of gases from speed of sound is presented. It is based on numerical integration of ordinary differential equations (ODEs) (rather than partial differential equations—PDEs) connecting speed of sound with other thermodynamic properties in the T-p domain. The procedure enables more powerful methods of higher-order approximation to ODEs to be used (e.g., Runge-Kutta) and requires only Dirichlet initial conditions. It was tested on gaseous argon in the temperature range from 250 to 450 K and in the pressure range from 0.2 to 12 MPa, and also on gaseous methane in the temperature range from 275 to 375 K and in the pressure range from 0.4 to 10 MPa. The density and isobaric heat capacity of argon were derived with absolute average deviations of 0.007% and 0.03%, respectively. The density and isobaric heat capacity of methane were derived with absolute average deviations of 0.006% and 0.09%, respectively.     

How Well Is Engineering Education Incorporating Societal Issues?

The formal undergraduate engineering curriculum of a leading North American university was examined in terms of the extent to which students learn to incorporate an understanding of how technology affects human life, society and the biosphere into engineering theory and design in order to ensure a greater compatibility between technology and its contexts. Faculty publications and theses were also examined. Given current economic, social and environmental trends and policies, the study shows cause for deep concern, while at the same time identifying a largely untapped potential for engineers to assist society in overcoming some of its current challenges while helping to reduce the drop-out rate and attract more persons to engineering.     

The delta-opioid receptor in SK-N-BE human neuroblastoma cell line undergoes heterologous desensitization

The human neuroblastoma cell line SK-N-BE expresses delta-opioid receptors negatively coupled to adenylyl cyclase. Prolonged treatment (2 h) of the cells with 100 nM etorphine leads to an almost complete desensitization (8.2 +/- 5.9 vs. 45.8 +/- 8.7% for the control). Other receptors negatively coupled to adenylyl cyclase, namely, D2-dopaminergic, alpha 2-adrenergic, and m2/m4-muscarinic, were identified by screening of these cells, and it was shown that prolonged treatment (2 h) with 1 microM 2-bromo-alpha-ergocryptine or 1 microM arterenol resulted in a marked desensitization of D2-dopaminergic and alpha 2-adrenergic receptors, respectively. Cross-desensitization experiments revealed that pretreatment with etorphine desensitized with the same efficiency the delta-opioid receptor and the D2-dopaminergic receptor, and pretreatment with 2-brorno-alpha-ergocryptine also desensitized both receptors. In contrast, pretreatment with etorphine desensitized only partly the alpha 2-adrenergic receptor response, whereas pretreatment with 1 microM arterenol partly desensitized the delta-opioid receptor response. It is concluded that the delta-opioid receptor-mediated inhibitory response of adenylyl cyclase undergoes heterolgous desensitization, and it is suggested that delta-opioid and D2-dopaminergic receptors are coupled to adenylyl cyclase via a G12 protein, whereas alpha 2-adrenergic receptor could be coupled to the enzyme via two G proteins, G12 and another member of the G1/G0 family.     

Cactus pear peel snacks prepared by instant pressure drop texturing: Effect of process variables on bioactive compounds and functional properties

Cactus pear (Opuntia ficus-indica) has a growing interest from both food manufacturers and consumers due to its medicinal and functional traits. Peel is a major waste from cactus pear juice industry accounting for about 38?% of the fruit weight. New concept of snacks preparation has been developed using instant controlled pressure drop (Détente instantanée controlee, DIC) techniques that provide a texturing stage between initial and final hot air drying stages. In this study, the application of DIC of cactus pear peel (CPP) was performed to be used as starch-free snacks with functional attributes. DIC resulted in high crispness CPP snacks with improved structural and nutritional attributes as well as high relative expansion ratio (up to 21 times). DIC expanded CPP snacks exhibited cutting force (3.34 N) that was much lower than untreated CPP (19.41 N). It is worth noting that optimized DIC treatment (P?=?0.6 MPa for t?=?15 s) allowed more availability of phenolic compounds and β-carotene by 83 and 551?%, respectively. In addition, antioxidant activity was increased up to 53?%. Results showed that steam pressure had significant effect on fat and alcohol insoluble solids (AIS) contents, wherein the correlation coefficients revealed critical relationships between structural and biochemical availabilities. Therefore, DIC could be used as an innovative technology to value this by-product leading to manufacture of crispy CPP snacks with high nutritious quality. There was a significant difference among the DIC treated and untreated CPP in respect to sensory properties, DIC treated CPP at operation conditions of saturated steam pressure?=?0.6 MPa and processing time?=?15 had the highest acceptability.