Heat Transfer to Non-Newtonian Fluid Foods under Laminar Flow Conditions in Horizontal Tubes

This paper presents a study of rates of heat transfer to non-Newtonian fluid foods: mango and papaya nectars, passing through horizontal tubes of circular cross section under laminar flow conditions. Determination of the flow and thermal properties of the fluids under study was performed to adequately explain heat transfer experiences. A laminar mixed convection equation was used for describing experimental heat transfer coefficients: Nu = 1.75 [Gz + 0.0083 (Gr_w . Pr_W)^0.75]^1/3 . δ^1/3 . (K_b/K_w)^0.14 The experimental data covered Graetz numbers between 500 and 7000, and were correlated with a mean deviation of 8.4%. The results should be helpful for interpreting heat transfer to pseudoplastic materials in the design of double tube heat exchangers.     

Solar Water Heating

This paper summarises one of the four final report titles published under CEC contract NO ES-A-P-009-UK(N), “Performance Monitoring of Solar Heating Systems in Dwellings (Part II)”.

The report described here contains measured monthly performance data from monitored solar water heating projects located in member countries of the European Community. Reported performance figures range from 400 to 1,200 MJm^? 2 p.a. (100 to 300 kWh/m² p.a.), which represents 10 to 30% of global radiation incident on the collectors. It is suggested that an annual performance of 1,000 to 1,400 MJm^? 2 p.a. is realistic as a performance target for better optimised systems.     

Cryopreservation of <i>Cyrtopodium hatschbachii</i> Pabst (Orchidaceae) immature seeds by encapsulation-dehydration

The aim of the present study was to investigate the efficiency of the encapsulation-dehydration technique for cryopreservation of Cyrtopodium hastchbachii Pabst seeds. Immature seeds of this species were cryopreserved by an encapsulation-dehydration technique. Seeds of five immature pods, 120 days after pollination, were encapsulated in 3% calcium alginate matrix and pretreated in liquid medium supplemented with 0.08 M sucrose (24 h), 0.15 M sucrose (24 h), 0.25 M sucrose (48 h), 0.5 M sucrose (24 h) and 0.75 M sucrose (24 h) in shaker at 60 rpm. Alginate beads were dehydrated 5 h in silicagel and immersed in liquid nitrogen for 12 h. Cryopreserved beads were thawed at 30°C for 1 min, rehydrated using the same liquid mediums [0.75 M sucrose (24 h), 0.5 M sucrose (24 h), 0.25 M sucrose (48 h) and 0.15 M sucrose (24 h)] and cultivated in half strength Murashige & Skoog medium (1962) with the addition of 2 g/L activated charcoal. Sixty four percent of seeds survived and developed into acclimatized plants after being cryopreserved. In this work, the encapsulation-dehydration technique was employed for first time in Cyrtopodium hatschbachii.     

Effects of resonant magnetic perturbations on radial electric fields in DⅢ-D tokamak

Gyrokinetic simulations of DⅢ-D tokamak equilibrium find that resonant magnetic perturbation(RMP) drives a neoclassical non-ambipolar electron particle flux,which causes a rapid change of equilibrium radial electric fields consistent with experimental observations during the suppression of the edge localized mode (ELM).The simulation results provide a support for the conjecture that RMP-induced changes of radial electric fields lead to the enhanced turbulent transport at the pedestal top during the ELM suppression (Taimourzadeh et a12019 Nucl.Fusion 59046005).Furthermore,gyrokinetic simulations of collisionless damping of zonal flows show that resonant responses to the RMP decrease the residual level of the zonal flows and damp the geodesic acoustic mode.     

Proton NMR and Dielectric Measurements on Sucrose Filled Agar Gels and Starch Pastes

Low-field proton NMR and high-frequency dielectric measurements were performed on sucrose-filled agar gels of 0 to 1.2g sucrose/g water and starch pastes of concentrations between 0.2 and lg starch/ g water. The dielectric constant decreased linearly with increasing concentration for both. The dielectric loss of sucrose-filled agar gels showed two regions, first increasing and then decreasing with concentration. The dielectric loss data for starch pastes showed a constant value close to that of pure water throughout the concentration range. Dielectric data were related to hydration models derived from proton NMR measurements.     

Chemical composition and microbial evaluation of Argentinean Corrientes cheese

The chemical and microbial composition of an artisanal cheese made from raw cow's milk produced and consumed in the province of Corrientes (north-eastern Argentina) was evaluated using standard methods. Corrientes cheese has high moisture content (50–60%), normal protein and fat contents (21–27 and 22–26% respectively), and is low in salt (0.5–2.0% w/w). Microbial counts also varied significantly between samples (colony-forming units per gram ranges covering logs of 5–11), probably due to environmental contamination in the raw material. These results will help produce higher quality Corrientes cheeses with well-defined characteristics.     

An Examination of the Minimal Water Activity for Staphylococcus aureus ATCC 6538 P Growth in Laboratory Media Adjusted with Less Conventional Solutes

Present work investigated whether or not Staphylococcus aureus ATCC 6538 P growth may occur below a_w 0.86 in laboratory media adjusted by addition of less conventional a_w controlling solutes. Solutes examined included, 1-proline, 1-lysine, β-alanine, sorbitol, KC1, sodium lactate and polyethylene glycols. No growth was observed in any case at or slightly below a_w 0.86; thus Scott's (1953) general conclusion on the lowest limit for S. aureus growth remains unchallenged. Results obtained also showed that polyethylene glycols (M.W. 200 and 400) have a significant inhibitory effect on S. aureus ATCC 6538 P growth independent of a_w lowering.