Wetting in Binary Fluid Mixtures: Recent Resugts in H2/He on Cesium

We present the resugts of an experiment on the wetting of liquid hydrogen on a cesium substrate using helium as a surfactant. In contrast to the previously studied case of ³He-⁴He mixtures on cesium, there is less ambiguity about the concentration dependence of the liquid-solid surface tension, suggesting that the resugts may be more easily interpreted; however, the relatively high temperatures and pressures complicate both experiment and calculation. The thermal expansion of the liquid turns out to be a major contribution to the temperature variation of the liquid-solid surface tension. When this is taken into account, there is excellent agreement between the observed variation of the wetting temperature with helium concentration (?.31±0.01 K/bar) and the calculated value (?.30 K/bar).     

Organocatalytic Enantioselective Decarboxylative Addition of Malonic Half Thioesters to Imines

We describe a biomimetic organocatalytic enantioselective decarboxylative addition of malonic acid half thioesters to imines. This simple protocol makes use of readily available Cinchona‐derived organocatalysts and nucleophiles at the carboxylate oxidation state. The resulting β‐amino thioesters, being attractive precursors for the preparation of optically active β‐amino acids, are formed in good yields and in up to 79 % ee. As suggested by several mechanistic insights the desired products are formed via initial formation of a thioester acetate enolate via decarboxylation of the malonic acid half thioester, followed by addition to the imine.     

Surfactants for Exploring the Liquid–Solid Surface Free Energy

Helium-3 and helium-4 can be used as surfactants to modify the observed wetting transitions of hydrogen and deuterium on rubidium. The effect of these surfactants on the wetting temperature is calculated. Prewetting induced by ⁴ He in H ₂ on Rb is studied, and found to be re-entrant. Experiments can use the effect to measure the difference in temperature and concentration dependence of a free solid surface and a liquid/solid interface. This may help to resolve some unresolved questions pertaining to the wetting behavior of helium isotopic mixtures on cesium.     

Effect of different colored filters on photooxidation in pasteurized milk

The effect of different colored filters and atmospheres on photooxidation and quality in milk was studied. Pasteurized bovine milk (3.9% fat) was packed in 2 different atmospheres (air and N₂) and exposed to light for 20 h at 4°C under 8 transparent filters with different light transmission properties. The following transparent, noncolored, and colored filters based on polyethylene terephthalate (PET) were used: noncolored (PET), noncolored with 2 different UV-block regions, yellow, green, amber, orange, and red. Control samples were stored in darkness and in a carton. Sensory evaluation showed off flavors significantly increased in milk stored under all filters compared with the control samples. Variation in atmosphere resulted in significant differences in formation of rancid flavor in milk stored under different filters. Milk samples stored in N₂ underwent the most sensory deterioration under orange and red filters, whereas milk samples stored in air were most deteriorated under noncolored filters. According to the oxidation compounds measured by gas chromatography, milk samples stored under noncolored and orange filters were highly oxidized, whereas red, green, and amber filters offered better protection against photooxidation. Fluorescence spectroscopy was used to examine the degradation of photosensitizers (riboflavin, protoporphyrin, and chlorophyllic compounds) in the milk samples. Degradation of protoporphyrin and chlorophyllic compounds in N₂ correlated well with sensory properties related to photooxidation (R² = 0.75-0.95). The study indicates that protoporphyrin and chlorophyllic compounds were effective photosensitizers in milk. To avoid photooxidation in milk, it is therefore important to protect it against light from the UV spectrum as well as light from the entire visible region.     

Fishmeal and oil from lantern fish (Myctophidae) with special emphasis on protein quality

Fishmeal made from lantern fish (family: Myctophidae; genus: Benthosema pterotum) had proximate, mineral, amino acid and fatty acid composition within the range reported for fishmeal made from conventional fish. Similarly, the pressed-out oil had a fatty acid composition and content of unsaponifiables as reported for conventional fish oil. The content of unsaponifiables in the body fat of the fish indicated that wax esters contributed a minor part of the lipids of this species of lantern fish. Determined in chicks, the true digestibility of the amino acids varied from 92% (arginine) to 73% (hydroxyproline) which for most of the amino acids was 1-3% units lower than that found for a high-quality capelin fishmeal. No differences in rate of mortality, growth rate and feed consumption and utilisation were found between lantern and capelin fishmeal when they replaced increasing amounts (0 to 100%) of soya bean meal as protein supplements (72% of total protein) to cereal diets, both fishmeals reducing feed consumption and causing a significant improvement in feed utilisation compared with soya bean meal. The data indicate that lantern fish may be used for the production of fishmeal.     

Rapid Assessment of Rancidity in Complex Meat Products by Front Face Fluorescence Spectroscopy

ABSTRACT: Front face autofluorescence from meat products was measured to elucidate the method's ability to measure and predict lipid oxidation. Three sample sets were studied: turkey meat with added aldehydes, raw and heat-treated turkey meat, and meat loaf at different process steps. Multivariate regression was used to correlate against sensory assessed rancidity, volatile compounds (GC-MS), and TBARS. Results verified that the increase in fluorescence during storage originates from aldehydes reacting with the meat matrix. Fluorescence modeled sensory assessed rancidity at the same accuracy as volatile compounds (R = 0.9), but was superior to TBARS. Front face fluorescence seems to be a powerful tool for nondestructive analysis of oxidation progress in meat products.     

Trans fatty acids. 2. Fatty acid composition of the brain and other organs in the mature female pig

Female pigs were fed from three wk of age and up to two years a diet containing partially hydrogenated fish oil (PHFO, 28%trans monoenoic fatty acids), partially hydrogenated soybean oils (PHSBO, 36%trans fatty acids) or lard. No consistent differences were found between PHFO and PHSBO with regard to incorporation oftrans fatty acids in organ lipids, buttrans incorporations were highly organ-specific. Notrans fatty acids were detected in brain phosphatidylethanolamine (PE). The incorporation of monoenoictrans isomers, as a percentage of totalcis + trans, in other organs was highest in subcutaneous adipose tissue and liver mitochondria PE, followed by blood lipids with the lowest level in heart PE. The percentage oftrans isomers compared with that of dietary lipids was consistently lower for 20∶1, compared with 18∶1 in organs from PHFO-fed pigs. The only effect of dietarytrans fatty acids on the fatty acid pattern of brain PE was an increased level of 22∶5n−6. Heart PE and total serum lipids of pigs fed the hydrogenated fats contained higher levels of 18∶2n−6, and these lipids of the PHFO-fed group also contained slightly elevated amounts of 20∶3n−6, 18∶3n−3 and 20∶5n−3. Liver mitochondria PE of the PHFO group also contained higher levels of 20∶3n−6 and 22∶5n−6. Dietarytrans fatty acids caused a consistent decrease of saturated fatty acids compensated by increased levels of monoenes. Thus, it may be concluded that dietary long-chaintrans fatty acids in PHFO behaved similarly metabolically to 18∶1-trans in PHSBO in pigs, without noticeable influence on brain PE composition and with moderate to slight effects on the fatty acid profile of the other organs.     

Critical review: life-cycle inventory procedures for long-term release of metals

Life-cycle assessment (LCA) is the method of inventorying, assessing, and interpreting environmental interventions caused by products and product systems through their life cycle. The ecotoxicity of metals has proven a challenge for LCA given metal characteristics such as reversibility of removal processes, speciation, and the effect on bioavailability and ecotoxic effect assessment. Our review focuses on the first part of the ecotoxic impact chain for metals, i.e., the release of metals from solid deposits. According to the principle of temporal justice, sustainability assessment tools such as LCA should accountfor emissions regardless of temporal location distribution. This is in LCA commonly interpreted as leaching until depletion of metals bound in solid wastes under the presumption that infinite time implies infinite weathering. This approach is risk conservative for metals and it hampers the use of LCA to assess remediation projects for soils and sediments contaminated by inorganic substances. We discuss metal significance and inventory issues in LCA, and review existing and proposed approachesto make LCA applicable to metal long-term emission.     

Myosins from red and white bovine muscles: Differences measured by turbidimetric,calorimetric and rheological techniques

The aim of this study was to elucidate the functional performance of the most abundant protein component in meat, ie myosin, which is recognised as important for binding in meat products. As several genetic variants of skeletal myosin exist, myosins from two bovine muscles of different fibre type composition, M masseter and M cutaneus trunci were compared with respect to filament forming properties and denaturation characteristics. The principal methods used were turbidimetric measurements, which were used to monitor filament formation, calorimetry and rheology. The myosin systems were examined at two different salt levels (0.2 and 0.6 M NaCl) and at pH 5.5–7.0. The method of preparing myosin suspensions/solutions was also examined. Differences in the filament-forming process for the two myosins were detected. Measurements of turbidity revealed that at conditions of low pH and low ionic strength white myosin had a higher ultimate turbidity compared with red myosin. Early in the transition from low to high turbidity, red myosin had a higher turbidity than white myosin corresponding to reduced solubility. The turbidity increased with time of storing the myosin suspensions/solutions. This change was attributed to formation of filaments and further association of filaments. White myosin had a smaller apparent enthalpy of denaturation than red myosin. The calorimetric measurements recorded in 0.2 M NaCl suggested that the head and the rod of white myosin were less stable than the corresponding parts of red myosin. However, exceptions to this rule were found at pH 6.0. In 0.6 M NaCl the identification of the transitions for red myosin was more difficult. The method of preparing myosin suspensions affected calorimetric and rheological measurements. In 0.6 M NaCl and pH 6.0 calorimetric thermograms of both myosins were affected by the preparation method. At pH 5.5 this change was interpreted as caused by denaturation promoted by the dilution/rapid titration technique compared with dialysing the systems to pH 5.5 from pH 7. Differences in the filaments formed might, however, also contribute to the variations seen in the calorimetric ther-mograms. The gelling properties of white myosin were most sensitive to the preparation method used. Systems prepared by dialysis gave stronger heat-induced gels than those prepared by ‘dilution’. White myosin always produced stronger gels than red myosin independent of the preparation technique. The rheological properties (at 80°C) of red myosin were less affected by the preparation method than were those of white myosin. At lower temperatures, however, there was more variation in the shapes of the rheological thermograms (? versus temperature) for red myosin than in the corresponding thermograms of white myosin.