Input,flux, and persistence of six select pesticides in San Francisco Bay

Temporal patterns of pesticide inputs to San Francisco Bay were identified and correlated with timing of application and transport mechanism. Fluxes were calculated from measured concentrations and estimated flow. Persistence of the pesticides under typical riverine or estuarine conditions were estimated from laboratory experiments. Simazine was detected most frequently and had the highest flux into the Bay, which could be explained by its continuous use and long half-life. In comparison, diazinon was detected at lower concentrations and had a lower flux which corresponded to its lower use and shorter half-life. The order-of-magnitude lower fluxes of carbofuran and methidathion corresponded to their lower use and expected hydrolysis. Molinate was detected at the highest concentration but its flux was lower than expected, considering its very high use and persistence in the laboratory experiments. Additional loss of molinate is likely to occur from volatilization and photodegradation on the rice fields. Although thiobencarb had the second highest use, it had the lowest flux of the six pesticides, which can be attributed to its loss via hydrolysis, photodegradation, volatilization, and sorption to sediments. Fluxes into San Francisco Bay were equal to or greater than those reported for other estuaries, except for the Gulf of Mexico.     

Magtrieve™: a convenient catalyst for the oxidation of alcohols

We find that Magtrieve™ (CrO₂) catalyzes the oxidation of a wide variety of alcohols with periodic acid as the terminal oxidant. Mild conditions, short reaction times, and facile aqueous work-up make this a most attractive method. Olefins are not oxidized under these conditions; thus alcohols react selectively in the presence of alkenes. Conditions have been optimized with respect to catalyst loading, solvent, and co-oxidant; and the scope of the reaction includes primary and secondary benzylic, allylic, and aliphatic alcohols.     

Molecular Fluorescence Imaging Spectroscopy for Mapping Low Concentrations of Red Lake Pigments: Van Gogh's Painting The Olive Orchard

Vincent van Gogh used fugitive red lake pigments that have faded in some paintings. Mapping their distribution is key to understanding how his paintings have changed with time. While red lake pigments can be identified from microsamples, in situ identification and mapping remain challenging. This paper explores the ability of molecular fluorescence imaging spectroscopy to identify and, more importantly, map residual non‐degraded red lakes. The high sensitivity of this method enabled identification of the emission spectra of eosin (tetrabromine fluorescein) lake mixed with lead or zinc white at lower concentrations than elemental X‐ray fluorescence (XRF) spectroscopy used on account of bromine. The molecular fluorescence mapping of residual eosin and two carmine red lakes in van Gogh's The Olive Orchard is demonstrated and compared with XRF imaging spectroscopy. The red lakes are consistent with the composition of paint tubes known to have been used by van Gogh.     

Dodecyl sulfate-hydrotalcite nanocomposites for trapping chlorinated organic pollutants in water

A series of hybrid organic-inorganic nanocomposite materials was synthesized by three different procedures using sodium dodecyl sulfate (DDS) and magnesium-aluminum layered double hydroxide (Mg/Al LDH with a Mg/Al molar ratio of 2 to 5). Both the pH of the exchange medium (6.5 to 10) and the Mg/Al molar ratio of the LDH affected the basal spacing, the content of DDS retained and the orientation of the DDS chains within the interlamellar space. For LDH with higher charge density (Mg/Al=2 and 3), DDS molecules likely formed a perpendicular monolayer within the LDH interlayer and the solution pH had little effect on the basal spacing, with a mean and standard deviation of 25.5+/-0.4 A. However, for LDH with lower charge density (Mg/Al=4 and 5), DDS molecules more likely formed an interpenetrating bilayer, and the basal spacing significantly increased with increasing pH, with a mean and standard deviation of 32.7+/-5.2 A. Sorption of trichloroethylene and tetrachloroethylene by DDS-LDH varied with synthesis conditions, LDH type and DDS configuration in the interlayer. DDS-Mg(3)Al-LDH had the highest affinity for both trichloroethylene and tetrachloroethylene in water, either comparable to or as much as four times higher than other clay-derived sorbents, followed by DDS-Mg(4)Al-LDH and DDS-Mg(5)Al-LDH. DDS-Mg(2)Al-LDH had the lowest sorption affinity although the highest amount of DDS. The pH of the exchange solution also affected the amount of DDS retained by the LDH as well as the sorption efficiency. Mg(3)Al-LDH has a charge equivalent area of 32.2 A(2)/charge, which allows the formation of optimal DDS configuration within its interlayer, thus resulting in the highest affinity for the chlorinated compounds. The DDS-Mg/Al-LDHs can be easily synthesized either ex situ or in situ at low temperature, indicating the feasibility of practical applications. The results obtained by controlling the synthesis procedure suggest that different arrangements of DDS molecules in the LDH interlayers can be obtained and optimized for the sorption of specific sorbates.     

Selective hydrolysis of peptides promoted by metal ions: a positional scanning approach

Rapid, microplate-based fluorogenic screening of a positional scanning combinatorial library accurately predicts the sequence specificity of metal-assisted peptide hydrolysis.     

A new approach for the large-scale generation of mature dendritic cells from adherent PBMC using roller bottle technology

Background  

Human monocyte-derived DC (mDC) loaded with peptides, protein, tumor cell lysates, or tumor cell RNA, are being tested as vaccines against multiple human malignancies and viral infection with great promise. One of the factors that has limited more widespread use of these vaccines is the need to generate mDC in large scale. Current methods for the large-scale cultivation of mDC in static culture vessels are labor- and time- intensive, and also require many culture vessels. Here, we describe a new method for the large-scale generation of human mDC from human PBMC from leukopheresis or buffy coat products using roller bottles, never attempted before for mDC generation. We have tested this technology using 850 cm² roller bottles compared to conventional T-175 flat-bottom static culture flasks.