Electrical sintering of nanoparticle structures

A method for sintering nanoparticles by applying voltage is presented. This electrical sintering method is demonstrated using silver nanoparticle structures ink-jet-printed onto temperature-sensitive photopaper. The conductivity of the printed nanoparticle layer increases by more than five orders of magnitude during the sintering process, with the final conductivity reaching 3.7 × 10(7)?S?m(-1) at best. Due to a strong positive feedback induced by the voltage boundary condition, the process is very rapid-the major transition occurs within 2?μs. The best obtained conductivity is two orders of magnitude better than for the equivalent structures oven-sintered at the maximum tolerable temperature of the substrate. Additional key advantages of the method include the feasibility for patterning, systematic control of the final conductivity and in situ process monitoring. The method offers a generic tool for electrical functionalization of nanoparticle structures.     

ESTERASES OF BAKER'S YEAST. III. THE ESTER/ACID RATIO IN MODEL SOLUTIONS

Ester/acid equilibria were studied in reaction mixtures containing ethyl alcohol, ethyl caprylate or caprylic acid, and baker's yeast or an esterase purified from baker's yeast in buffer. The equilibrium concentration of ethyl caprylate after an incubation of yeast or a yeast esterase preparation with caprylic acid was the same as in the case where yeast or esterase preparation was incubated with the ethyl caprylate. The equilibrium attained depends not only on the concentration of the ester and the alcohol but also on the pH, the final ester concentration remaining higher at low pH. It could be shown that yeast esterase is responsible for the hydrolysis or synthesis of the ester. At equilibrium the molar ratio of ethyl caprylate/caprylic acid is about the same as that found in fermentation solutions under the same conditions.     

Volatile compounds of blackcurrant juice and wine

Volatile compounds of blackcurrant juice, concentrate and wine were analysed by applying a dynamic headspace gaschromatographic method based on selective capillary column trapping. A significant sensorial difference between the wine made from blackcurrant juice and that from concentrate was found by duo-trio assessment for aroma, while only a slight difference was observed in the volatile composition of the wines. Blackcurrant wines contained only a few terpene compounds, whereas numerous terpenes were identified from the juice. Differences between the blackcurrant juice and concentrate were found, with some terpene compounds appearing in higher amounts in the former.

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Flüchtige Verbindungen im Saft und im Wein der Schwarzen Johannisbeere

Zusammenfassung Flüchtige Verbindungen von Saft, Konzentrat und Wein der Schwarzen Johannisbeere wurden mittels der dynamischen Kopfraum-gaschromatographischen Methode untersucht, wobei die flüchtigen Substanzen selektiv mit einer Capillarsäule erfaßt wurden. Es konnten bei der Duo-trio-Bestimmung des Aromas signifikante sensorische Unterschiede zwischen dem Wein aus Saft und dem Wein aus Konzentrat festgestellt werden, während ein nur geringer Unterschied bei der Zusammensetzung der flüchtigen Verbindungen der Weine zu beobachten war. Die Weine aus der Schwarzen Johannisbeere enthalten nur wenige terpene Verbindungen, bei Saft dagegen konnte eine größere Anzahl an Terpenen nachgewiesen werden. Bei dem Vergleich von Saft und Konzentrat zeigte sich ein höherer Anteil an terpenen Verbindungen im Saft.

     

THE ESTERASES OF BAKER'S YEAST. I. ACTIVITY AND LOCALIZATION IN THE YEAST CELL

The activity of esterase in baker's yeast cells and in cell fractions was estimated using 2-oxoglutaric acid diethyl ester, p-nitrophenyl acetate and α- and β-naphthyl acetate as substrates. The esterase hydrolysing 2-oxoglutaric acid ester was shown to be located inside the cell, both directly by an enzymic method and by indirect evidence. The activities of the esterases hydrolysing aryl esters were found to vary greatly with the different substrates and estimation methods used. The presence of esterase activity towards phenyl and naphthyl esters in both cell wall digests and sphaeroplast lysates confirms the localization of at least one esterase in both sides of the plasma membrane barrier. Depending on the method of evaluation, values between 80 and 40% of the total were obtained for the proportion of esterase activity located outside the plasma membrane, the most reliable values being about 50–65%.     

Predicting effects of exploitation rate on weight-at-age, population dynamics, and bioaccumulation of PCDD/Fs and PCBs in herring (Clupea harengus L.) in the Northern Baltic Sea

The Baltic Sea ecosystem and fish stocks contain high concentrations of environmental chemicals such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs). This study forecasts how changes in fishing or natural mortality would probably influence concentrations of PCDD/F and PCB in the Bothnian Sea (Northern Baltic) herring (Clupea harengus L.). An age-structured simulation model was developed to forecast herring stock dynamics, catches, and weight-at-age under different assumptions about exploitation and natural mortality. The simulated herring weight-at-age estimates were employed in a bioenergetics model capable of simultaneous estimation of bioaccumulation of 17 PCDD/F and 37 PCB congeners. Although the natural variability in recruitment greatly influences the stock dynamics, considerable changes in weight-at-age would ensue changes in exploitation rate or in natural mortality rate. If exploitation rates increase, growth rates would be higher and herring in the weight categories of commercial fisheries would be younger and contain less PCDD/F and PCB. Hence, the average toxicant concentrations in catches would also decline. However, it is likely that only fairly small changes would occur in toxicant concentrations-at-age. On the other hand, a drastic decrease in herring fishing would substantially increase PCDD/F and PCB concentrations in herring. The study indicated that, in spite of the clear influences of fishing on the toxicant concentrations, fishing alone cannot resolve the problems associated with a high concentration of toxicants in herring; further decreases in loading are still required.     

The effect of enzymatic treatment on blackcurrant (Ribes nigrum) juice flavour and its stability

The effects of different enzymatic treatments on the sensory profile and chemical composition, especially various phenolic compounds, sugars and fruit acids, of blackcurrant juices were investigated. In addition to pectinolytic activities, the enzymes had different cellulolytic, hemicellulolytic and glycolytic activities. The enzymatic treatments improved significantly the yield of juice, but with more fermented and astringent characteristics than juices without enzymatic hydrolysis. Enzymes with higher glycosidase activity increased astringency and the content of phenolic compounds in the juice. When the incubation temperature was elevated the contents of fruit acids increased whereas sugars and the perceived sweetness were the highest in the juices without enzymatic treatments. Despite of the significant changes in chemical composition, the sensory properties did not change significantly during 6 weeks of storage. Optimisation of the enzymatic process is crucial for juice making as maximising the juice yield or the content of phenolic compounds may produce unwanted sensory properties to the juice.     

Persistence of probiotic strains in the gastrointestinal tract when administered as capsules, yoghurt, or cheese

Most clinical studies of probiotics use freeze-dried, powdered bacteria or bacteria packed in capsules. However, probiotics are commercially available in various food matrices, which may affect their persistence in the gastrointestinal tract. The objective of the study was to compare oral and faecal recovery during and after administration of a combination of Lactobacillus rhamnosus GG and LC705, Propionibacterium freudenreichii subsp. shermanii JS, and Bifidobacterium animalis subsp. lactis Bb12 as capsules, yoghurt, or cheese. This randomized, parallel-group, open-label trial (n = 36) included a 4-week run-in, 2-week intervention, and 3-week follow-up period. Participants consumed 10¹⁰ cfu/day of probiotic combination and provided saliva and faecal samples before, during, and after the intervention. Strain-specific real-time PCR was used to quantify the strains.L. rhamnosus GG was the only probiotic strain regularly recovered in saliva samples. During the intervention period it was recovered in the saliva of 88% of the volunteers at least once. No difference was found between the yoghurt and cheese groups. At the end of the intervention, L. rhamnosus GG and LC705 counts were high in faecal samples of all product groups (8.08 and 8.67 log₁₀ genome copies/g, respectively). There was no matrix effect on strain quantity in faeces or the recovery time after ceasing the intervention. For P. freudenreichii subsp. shermanii JS and B. animalis subsp. lactis Bb12, a matrix effect was found at the end of the intervention (P < 0.01 and P < 0.001, respectively) and in the recovery time during follow-up (P < 0.05 for both). Yoghurt yielded the highest faecal quantity of JS and Bb12 strains (8.01 and 9.89 log₁₀ genome copies/g, respectively). The results showed that the administration matrix did not influence the faecal quantity of lactobacilli, but affected faecal counts of propionibacteria and bifidobacteria that were lower when consumed in cheese. Thus, the consumption of probiotics in yoghurt matrix is highly suitable for studying potential health benefits and capsules provide a comparable means of administration when the viability of the strain in the capsule product is confirmed.     

The association of noise sensitivity with coronary heart and cardiovascular mortality among Finnish adults

The association of coronary heart and cardiovascular mortality with noise sensitivity was studied. We also investigated how this association is affected by self-reported lifetime noise exposure. In 1988 a case-control study, based on the Finnish Twin Cohort, was carried out to investigate the relationship between noise and hypertension (n=1495). Potential confounders were obtained from questionnaire in 1981 for the same individuals. Data on deaths and causes of death were obtained from record linkage to the nationwide register of death certificates. All deaths that occurred among the study population during the 15 years of follow-up were classified as being due to all causes (n=382), to cardiovascular diseases (n=193), including the number of deaths due to coronary heart diseases (n=111) and to other causes than cardiovascular diseases (n=189). Cardiovascular mortality (Hazard ratio 1.80, 95% CI 1.07-3.04) was significantly increased among noise-sensitive women. Among men, there were no statistically significant effects. Noise sensitivity may be a risk factor for cardiovascular mortality in women.