Physical Thermodynamic Model of Alkali and Alkaline-Earth Fluorozirconate Glass-Forming Melts

A physical model for the thermodynamics of glass-forming alkali and alkaline-earth fluorozirconate melts is presented that takes into consideration the strong negative deviation from ideal behavior that is manifested by deep eutectic wells in the phase diagrams and large exothermic heats of mixing. The model is based on chemical equilibria between anionic complexes with six- to eight-fold coordination of zirconium and a simple Temkin model for the free energy of mixing. Calculated phase diagrams and liquidliquid heats of mixing agree well with the experimental data. The model predicts six-fold coordination of zirconium in glass-forming melts, which implies that the fragile nature of fluorozirconate glasses can be explained by a significant increase in the coordination of zirconium when the melt is quenched to the glassy state.     

Load-carrying capacity of a journal bearing under dynamic loading

A method of obtaining the simultaneous solution of the Reynolds equation for dynamically loaded bearings by using a suitable numerical method is briefly outlined. It is assumed that the relation between the relative radial velocity and the hydrodynamically effective angular velocity of the journal is known. The solution is illustrated by graphs and a table. Examination of the application of separate solutions of the Reynolds equation in Holland's method for solving the motion of the journal centre suggests that an error exists which is not always negligible. Therefore a modification of Holland's method based on the simultaneous solution derived in this paper is proposed.     

Analysis of a new algorithm for one-dimensional minimization

Davidon has recently introduced a new approach to optimization using the idea of nonlinear scaling. In this paper we study the algorithm that results when applying his ideas to the one-dimensional case. We show that the algorithm is locally convergent withQ-order equal 2 and compare it with the method of cubic interpolation.     

Effects of dietary phenolic compounds on tocopherol, cholesterol, and fatty acids in rats

The effects of the phenolic compounds butylated hydroxytoluene (BHT), sesamin (S), curcumin (CU), and ferulic acid (FA) on plasma, liver, and lung concentrations of α- and γ-tocopherols (T), on plasma and liver cholesterol, and on the fatty acid composition of liver lipids were studied in male Sprague-Dawley rats. Test compounds were given to rats ad libitum for 4 wk at 4 g/kg diet, in a diet low but adequate in vitamin E (36 mg/kg of γ-T and 25 mg/kg of α-T) and containing 2 g/kg of cholesterol. BHT significantly reduced feed intake (P<0.05) and body weight and increased feed conversion ratio; S and BHT caused a significant enlargement of the liver (P<0.001), whereas CU and FA did not affect any of these parameters. The amount of liver lipids was significantly lowered by BHT (P<0.01) while the other substances reduced liver lipid concentrations but not significantly. Regarding effects on tocopherol levels, (i) feeding of BHT resulted in a significant elevation (P<0.001) of α-T in plasma, liver, and lung, while γ-T values remained unchanged; (ii) rats provided with the S diet had substantially higher γ-T levels (P<0.001) in plasma, liver, and lung, whereas α-T levels were not affected; (iii) administration of CU raised the concentration of α-T in the lung (P<0.01) but did not affect the plasma or liver values of any of the tocopherols; and (iv) FA had no effect on the levels of either homolog in the plasma, liver, or lung. The level of an unknown substance in the liver was significantly reduced by dietary BHT (P<0.001). BHT was the only compound that tended to increase total cholesterol (TC) in plasma, due to an elevation of cholesterol in the very low density lipoprotein + low density lipoprotein (VLDL+LDL) fraction. S and FA tended to lower plasma total and VLDL+LDL cholesterol concentrations, but the effect for CU was statistically significant (P<0.05). FA increased plasma high density lipoprotein cholesterol while the other compounds reduced it numerially, but not significantly. BHT, CU, and S reduced cholesterol levels in the liver TC (P<0.001) and percentages of TC in liver lipids (P<0.05). With regard to the fatty acid composition of liver lipids, S increased the n-6/n-3 and the 18∶3/20∶5 polyunsaturated fatty acids (PUFA) ratios, and BHT lowered total monounsaturated fatty acids and increased total PUFA (n−6+n−3). The effects of CU and FA on fatty acids were not highly significant. These results suggest some in vivo interactions between these phenolic compounds and tocopherols that may increase the bioavailability of vitamin E and decrease cholesterol in rats.     

Effect of Infrared Blanching on Enzyme Activity and Retention of β‐Carotene and Vitamin C in Dried Mango

The objectives of this work were to evaluate infrared (IR) dry blanching in comparison with conventional water blanching prior to hot air drying of mango to inactivate polyphenol oxidase (PPO) and ascorbic acid oxidase (AAO) enzymes, and to study its effect on color change and retention of vitamin C and β‐carotene. Mango cylinders were blanched under similar temperature–time conditions either by IR heating or by immersion in a water bath during 2 min at 90 °C (high‐temperature‐short‐time—HTST) or for 10 min at 65 °C (low‐temperature‐long‐time—LTLT). After blanching mango was hot air dried at 70 °C. PPO was completely inactivated during the blanching treatments, but AAO had a moderate remaining activity after LTLT treatment (～30%) and a low remaining activity after HTST treatment (9% to 15%). A higher retention of vitamin C was observed in mango subjected to IR dry blanching, 88.3 ± 1.0% (HTST) and 69.2 ± 2.9% (LTLT), compared with water blanching, 61.4 ± 5.3% (HTST) and 50.7 ± 9.6% (LTLT). All‐trans‐β‐carotene retention was significantly higher in water blanched dried mango, 93.2 ± 5.2% (LTLT) and 91.4 ± 5.1% (HTST), compared with IR dry blanched, 73.6 ± 3.6% (LTLT) and 76.9 ± 2.9% (HTST). Increased levels of 13‐cis‐β‐carotene isomer were detected only in IR dry blanched mango, and the corresponding dried mango also had a slightly darker color. IR blanching of mango prior to drying can improve the retention of vitamin C, but not the retention of carotenoids, which showed to be more dependent on the temperature than the blanching process. A reduction of drying time was observed in LTLT IR‐blanching mango.     

Comparative study on acute effects of water accommodated fractions of an artificially weathered crude oil on Calanus finmarchicus and Calanus glacialis (Crustacea: Copepoda)

Extrapolation of ecotoxicological data from temperate species for use in risk assessment in the polar environments may be difficult since polar organisms as a rule differ from temperate species in terms of life span length, developmental time, surface-to-volume ratios, metabolic rates, total energy usage and lipid content for energy storage. In the current work we performed a comparative study where two closely related and morphologically similar copepod species, Calanus finmarchicus (temperate-boreal) and Calanus glacialis (arctic), were exposed to water accommodated fractions (WAF) of oil in a series of parallel experiments. The two species, adapted to 10 °C and 2 °C, respectively, were compared on the basis of acute ecotoxicity (LC₅₀) and the WAF-mediated induction of the gene encoding glutathione S-transferase (GST). In addition, an experiment was conducted in order to reveal relationships between lipid content and acute toxicity. LC₅₀ values differed between the two species, and the Arctic copepod appeared less sensitive than the temperate-boreal species. The lipid contents of the two species, measured biometrically, were comparable, and the relationships between lipid content and response (reduced survival) to acute WAF exposure followed the same trend: Lipid-rich copepods survived longer than lipid-poor copepods at the same exposure concentration. In terms of GST expression, both species showed concentration-dependent and exposure time-dependent trends. However, as for the acute toxicity data, the Arctic copepod appeared to respond slower and with a lower intensity. From the study it can be concluded that temperature and lipid content are important factors for assessing differences between temperate and Arctic species, and that a delayed response in organisms adapted to low temperatures needs to be corrected for when extrapolating toxicity data from species with other temperature optimums for use in Arctic environments.     

Biotope patterns and amphibian distribution as assessment tools in urban landscape planning

We investigated how information on biotope patterns over time and spatio-temporal distribution patterns of focal species (amphibians) in Stockholm, can assist in identifying landscape-ecological zones and give support to urban planning. Species data were combined with biotope patterns interpreted from aerial photographs (1998 and 1945/1950). These were then compared with information on roads with heavy traffic (1998 and 1950), with anticipated serious isolation effects. Spatial analyses were conducted using GIS (ArcView). We found that temporal distribution of amphibians is negatively related to increased fragmentation of valuable biotope configurations. Our use of context sensitive data on biotopes and species, provided insight into the ability of ecosystems to buffer land cover changes. We identified a time-lag of several decades between changes in urban land and road traffic intensity, and the response in species occurrence. This time-lag is not recognised in present-day planning and, therefore, the view of the status of wetland biodiversity in Stockholm’s natural and semi-natural areas remains too optimistic. To maintain the resilience of biotopes in urban areas, we argue that organisations responsible for implementing any active plan regarding biodiversity should more fully consider comprehensive reference data in their analysis programme, i.e. biotope and species data with a time-span that covers all land and waters in the given municipality. This is to develop a greater capacity to adapt physical planning work to the different risk of biodiversity loss in specifically chosen areas.     

Effects of lactic acid concentration and spray drying conditions on stickiness of acidified skim milk powder

The effects of lactic acid concentration (LA) and spray drying conditions on stickiness of acidified skim milk powder (SMP), which impacts process efficiency and powder properties, were examined using a fully replicated 2^4-1 fractional factorial design. The wall deposition was significantly affected by LA, and yield was positively influenced by the drying temperature difference. Drying temperature difference significantly affected particle size, moisture content and water activity of acidified SMP. Particle size was also significantly influenced by nozzle airflow rate. Moisture content and water activity were significantly affected by LA, while glass transition temperature was only influenced by the outlet temperature.     

Influence of partial acidification of skim milk on ultrafiltration performance and physicochemical properties of the produced streams

The influence of partial acidification of skim milk (SM) using glucono-δ-lactone (GDL), citric acid (CA) or lactic acid (LA), on physicochemical properties (e.g. viscosity and calcium balance) of ultrafiltration (UF) retentates produced at 10 and 55°C was investigated. Ultrafiltration retentates produced using CA showed a significantly lower amount (P < 0.05) of ionic calcium and higher apparent viscosity than GDL and LA. Regardless of the acid used, total calcium concentration and apparent viscosity of streams were modified compared with SM, which impaired UF overall performance. Specifically, CA at 10°C and GDL at 55°C, both reduced the permeate flux when compared to the other acids.