PCBs and OCPs on a East-to-West Transect: The Importance of Major Currents and Net Volatilization for PCBs in the Atlantic Ocean

Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large section of the tropical Atlantic suggested net volatilization of PCBs to the atmosphere. Only for the higher chlorinated PCB 153 and hexachlorobenzene (HCB) were gradients near equilibrium detected. The use of passive samplers also enabled the detection of dichlorodiphenyltrichloroethane (DDT) and its transformation products across the tropical Atlantic, indicating net deposition. There were clear differences between the southern and northern hemisphere apparent in terms of atmospheric concentrations: Once the ship moved from the southern into the northern hemisphere air, concentrations of HCB and other organochlorine pesticides increased several-fold. For large swaths of the tropical Atlantic Ocean, neither PCB nor organochlorine pesticide dissolved concentrations varied much longitudinally, probably due to efficient mixing by ocean currents. In selected samples, dissolved concentrations reflected the influence of river plumes and major ocean currents far away from the continents. Dissolved concentrations of PCBs 28, 52, 101, 118, and HCB increased in the Amazon plume and the Gulf Stream. While the Amazon plume flushed only a few kg of PCBs and HCB, the Gulf Stream is potentially delivering tons of PCBs into the North Atlantic annually.     

Measurement of surface‐transfer coefficient values for CO2 absorption in lime solutions in presence of surfactants

A modified manometric apparatus has been used for the experimental determination of surface‐transfer coefficient values, used for the design calculations of various mass‐transfer equipments, for the absorption of carbon‐dioxide gas in saturated lime solution in presence of different types of surfactants. An analytical expression has been derived for estimation of the volume of gas absorbed, using the manometric data, for different times of absorption. The rate of gas absorption was found to remain constant initially for about 1 min and thereafter decreased with the progress of absorption time. Surface‐transfer coefficient values for gas absorption have been calculated using the experimental data of the volume of gas absorbed, without and with the addition of different concentrations of surfactants to the lime solutions. For a particular surfactant, surface‐transfer coefficient values were found to decrease with an increase in the concentration of surfactant in solution. The calculated values of the surface‐transfer coefficients for different surfactants are in close agreement with those reported in the literature.     

Pillared MWW zeolites MCM-36 prepared by swelling MCM-22P in concentrated surfactant solutions

Lamellar zeolite forms like layered MCM-22 precursor, MCM-22P, offer unprecedented opportunities for creating diversity of more open zeolite structures prepared post-synthesis by expanding and modifying the interlamellar space. This is a relatively unexplored area with regard to procedures ensuring easy, least destructive and most efficient expansion of layered zeolites. Herein we explore concentrated surfactant solutions with high pH for their ability to provide swollen MCM-22 that can be converted to the pillared MCM-36. High pH of the swelling solutions was obtained by addition of tetrapropylammonium hydroxide and by partial conversion of the surfactant chloride into hydroxide by ion exchange. The products were evaluated based on their X-ray diffraction characteristics, sorption properties, scanning electron microscopy and IR spectra as indicators of catalytic potential. The swelling/pillaring efficiency was judged based on BET surface area and depended on swelling conditions, especially the apparent basicity. There was an overall decrease in acid site concentration due to incorporation of inert silica pillars. The MCM-36 zeolite with the highest BET showed increased uptake of 2,6-di-tert-butyl-pyridine by 75% compared to the parent MCM-22 suggesting enhanced accessibility of acid sites for bulky probe molecules. We conclude that concentrated surfactant solutions can be effective in swelling MCM-22P even at room temperature but an optimal approach must balance many factors including yield and activity of the final product.     

Inference about long run canonical correlations

This article proposes methods for testing the null hypothesis that a number of so‐called long run canonical correlations (LRCCs) are zero. Two test statistics are proposed and their limiting distributions are derived under the null hypothesis. The finite sample properties of the tests are illustrated via a number of simulation studies that reveal the asymptotic theory provides a good guidance to behaviour in moderate or large sized samples. It is shown that the statistics provide a natural way for testing the asymptotic independence of two standardized sums. The usefulness of the tests is illustrated via the following examples: inference about cointegrating vector in a particular cointegration model; inference about break points in a cointegration model; moment estimation; parameter estimation in Generalized Method of Moments estimation.     

A method for identifying water foraging bees by refractometer analysis: a spotlight on daily and seasonal water collecting activities of Apis mellifera L.

The current discussion about the relevance of guttation as a water source for honey bees (Apis mellifera L.) draws attention to the activity of water foraging bees. However, due to the wide foraging range, field observations of water foraging bees are difficult to carry out. Therefore, samples of returning bees were collected in front of the entrance early in the morning as well as during the day in summer and autumn 2010. In the laboratory, honey sacs of bees without pollen or propolis were examined. Honey sac samples with a weight of ≥0.005?g were classified as successful foragers. For the determination of water or nectar foragers, the honey sac contents of successful foragers were analyzed with a refractometer. Due to the dilution and the precision of the refractometer, an accuracy of 5?% was possible. Based on the known range of sugar concentrations in nectars, the analyzed samples were divided into nectar foragers (25–65?% sugar) and water foragers (0–15?% sugar). The study reveals that nectar and water foraging bees can be discriminated by analyzing the honey sac extracts with a refractometer. In autumn, the water demand of honey bee colonies is almost exclusively covered by water collection, whereas during summer nectar is mainly used as a substitute for water. In general, water collection is not restricted to certain times of the day.     

Fatty acids and tocopherol levels in M. Longissimus dorsi of beef cattle in Sweden - A comparison between seasonal diets

This study investigated the influence of Swedish outdoor feeding systems on the fatty acid composition and tocopherol content of M. Longissimus dorsi from beef. Dietary effects of pasture (PA), silage, and silage supplemented with grain (SIG) were compared. Each dietary group consisted of six animals. Higher levels (P < 0.05) of polyunsaturated fatty acids (PUFA) were found in the PA treatment. The n − 6/n − 3 fatty acid ratio of total lipids in the muscle tissue was in the range 1.2–1.5. The SIG treatment increased the n − 6/n − 3 ratio and decreased the total PUFA content of muscle tissue. The lipid class composition and the content of -tocopherol in the meat showed no differences among treatments.     

Determination of Total Carbohydrate Content in Beer Using Its Pre-column Enzymatic Cleavage and HPLC-RI

Beside ethanol, carbohydrates are the main source of total energy in beer. While analyses of fermentable carbohydrates are important from the technological point of view, the total content of carbohydrates is relevant in terms of nutrition. A high-performance liquid chromatography (HPLC) method with refractometric (RI) detection was developed for determination of total carbohydrate content in beer. Using enzymatic reaction with amyloglucosidase, the carbohydrates were cleaved to yield glucose and short glucose oligomers of less than 10 units, and separated on HPLC ion exchanger Rezex RSO-Oligosaccharide column in Ag⁺ mode. Optimum parameters were established for the enzymatic sample treatment and for the HPLC separation of reaction products. Calibration curves of glucose, fructose, maltose and simultaneously analyzed glycerol ranged from 0.001 to 0.5 g/100 ml, correlation coefficients of all calibration curves were 0.9999. The instrumental limits of quantification were 0.001 g/100 ml and they were verified using repetitive injections, with coefficient of variation (CV) less than 10 % in five replicates. The method limit of quantification was 0.01 g/100 ml since it was necessary to dilute the beer samples before chromatographic analysis. Recovery of the method in non-alcoholic and alcoholic beer was 98.5 %, and 92.3 %, respectively. Finally, ten non-alcoholic and 15 alcoholic beers from Czech market were analyzed using the method, the average content of total carbohydrates in non-alcoholic and alcoholic beers being 4.21 and 3.70 g/100 ml, respectively. These results are in a good correlation with the real extract of beer, which is on average 4.58 and 4.27 g/100 ml.     

Monitoring of black tea fermentation process using electronic nose

Black tea fermentation is essentially an oxidation process. After the plucked tea leaves are treated by series of processes called withering (removal of moisture by air flow), pre-conditioning and CTC (essentially maceration and cutting of leaves), the leaves are subjected to the process of fermentation by exposing them to air by laying the cut tea leaves on floor, trough or moving conveyor under controlled temperature, humidity and air-flow conditions. During this process, the leaves change colour from green to coppery brown and the grassy smell gets transformed to floral smell. It is critical that the leaves be allowed to ferment only up to the desired limit and both under and over fermentation result in deteriorated quality of black tea. Out of the two detectable parameters (colour and smell), smell is very important since a strong, very specific fragrance emanates from the leaves once leaves are optimally fermented. A new electronic nose-based approach for monitoring of tea aroma during fermentation is proposed. Two methods namely the 2-Norm method (2NM) and the Mahalanobis distance method (MDM) were tested and the results were correlated with the results of colorimetric tests and human expert evaluation.     

Chlorinated phenols in human milk

The paper deals with the contamination of human milk with chlorinated phenols. The average and median concentrations of the chlorophenols investigated ranged from 0.75 to 9.74 g.kg^–1 and from being not detectable to 5.62 g.kg^–1, respectively, for the different compounds. The highest average and median levels were found for pentachlorophenol and 2,4,5-trichlorophenol. The concentrations determined were below the permissible levels.     

Polyacrylate-coated graphene-oxide and graphene solution via chemical route for various biological application

In this work, we have developed a polyacrylate-coated graphene-oxide and then chemically reduced them into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene-oxide/graphene. They show good colloidal stability in different aqueous buffer solution with pH ranging from 5 to 10, and these solutions are stable for more than a month. The polyacrylate-coated grapheme oxide/graphene has been characterized by X-ray photoemission spectroscopy (XPS) and micro-Raman spectroscopy. Based on good colloidal stability, this graphene-oxide/graphene is most suitable for the biological application.