Effect of hydrocarbon chain length of amphiphilic ruthenium dyes on solid-state dye-sensitized photovoltaics

We studied the influence of the hydrophobic hydrocarbon chain length of amphiphilic ruthenium dyes on the device performance in solid-state dye-sensitized solar cells. We found that the dyes with longer hydrocarbon chains gave higher efficiency values when used as a sensitizer in solid-state dye-sensitized solar cells. With increasing chain length, we observed higher currents and open-circuit voltages up to a limiting chain length. We attribute this improvement to the expected larger distance between TiO2 and the hole conductor, which seems to suppress recombination effectively.     

Structure-aided optimization of kinase inhibitors derived from alsterpaullone

In order to perform computer-aided design of novel alsterpaullone derivatives, the vicinity of the entrance to the ATP-binding site was scanned for areas that could be useful as anchoring points for additional protein-ligand interactions. Based on the alignment of alsterpaullone in a CDK1/cyclin B homology model, substituents were attached to the 2-position of the parent scaffold to enable contacts within the identified areas. Synthesis of the designed structures revealed three derivatives (3-5) with kinase-inhibitory activity similar to alsterpaullone. The novel 2-cyanoethylalsterpaullone (7) proved to be the most potent paullone described so far, exhibiting inhibitory concentrations for CDK1/ cyclin B and GSK-3beta in the picomolar range.     

Vertical distribution of sediment enzyme activities involved in the cycling of carbon, nitrogen, phosphorus and sulphur in three boreal rural lakes

Vertical distribution of eleven hydrolytic enzyme activities were investigated with fluorogenic model substrates in boreal rural lake sediments, Lake Uurainen (13 km(2)), Lake J?mij?rvi (9 km(2)) and Lake Pyylampi (0.068 km(2)), in Finland. The eleven hydrolytic enzyme activities were high into deep sediment layers indicating potential for turnover of organic matter in the permanently anoxic zones. The activities of beta-glucosidase, sulphatase and N-acetyl-glucosaminidase were similar in the three lakes independent on the ecological status of the lake. Acetate- and butyrate-esterase were more active than the other enzymes in the three lakes. These unspecific esterases had sediment activities in forest Lake Pyylampi close to those reported for boreal coniferous forest soils in Finland. Similar beta-cellobiosidase activities throughout the sediment depths indicated constant depolymerisation potential for cellulose.     

Fractionation of surface sediment fines based on a coupled sieve-SPLITT (split flow thin cell) method

In traditional sediment grain-size separation using sieve technique, the bulk of the organic matter passes through the smallest mesh size (generally 38 microm) and is not further fractionated. In this study, a common sieve separation has therefore been coupled with an extra high capacity split flow thin cell fractionation (EHC-SPLITT) instrument to separate the bulk surface sediment not only into size-based sieve fractions (> 100, 63-100, 38-63 and < 38 microm) but particularly to further fractionate hydrodynamically the fine fraction (< 38 microm) using the EHC-SPLITT. Compared to the few previous studies using a smaller high capacity (HC) SPLITT cell, the EHC-SPLITT evaluated in detail here has several advantages (e.g., 23 times higher throughput and allowance for large particle diameters). First, the EHC-SPLITT was calibrated with particle standards. Then, its ability to fractionate fine surface sediments hydrodynamically was demonstrated with material from biogeochemically distinct regimes using two cutoff velocities (1 and 6 m d(-1)). The results from particle standards indicated a good agreement between theory and experiment and a satisfactory mass recovery for the sieve-SPLITT method (80-97%) was observed for sediment samples. The mass distributions revealed that particles < 38 microm were predominant (70-90%), indicating the large need for a technique such as the EHC-SPLITT to further fractionate the fine particles. There were clearly different compositions in the EHC-SPLITT-mediated sub-fractions of the sediment fines as indicated by analyses of organic and inorganic parameters (POC, Si, Fe and Al). The EHC-SPLITT technique has the potential to provide information of great utility to studies of benthic boundary layer transport and off-shelf export and how such processes fractionate geochemical signals.     

Immobilization of arsenic in a tailings material by ferrous iron treatment

Weathering and internal dissolution processes in mining waste materials may mobilize elevated levels of arsenic (As), contaminating ground and surface waters. Treating the polluted waters with iron oxyhydroxides is an established remediation method. By contrast, little knowledge is available to stabilize As in source materials by treating it with Fe precipitates and, on this way, to prevent the generation of polluted waters. In the present work the efficiency of Fe(II) treatment on As immobilization in a tailings material (TM) was studied with regard to the Fe:As molar ratio, the influence of CaCO3 amendment, and the As desorption at continued intensive leaching of Fe-treated TM. Fe precipitates were created by aerobic treatment of TM with Fe(II)sulfate at several Fe:As molar ratios with or without adding CaCO3, followed by aging the Fe-treated TM. The As retention in the treated tailings was studied by 4-fold elution with water, and the As desorption kinetics was examined by suspension leaching in laboratory microcosms over 3 weeks. Fe(II) treatment of TM reduced the water-extractable total As to <10 microg/L as the Fe:As molar ratio increased from 0 to 8. The water-soluble As of Fe-treated tailings could be reduced to 10-30 microg/L also under conditions of intensive leaching. Stabilizing the pH with CaCO3 resulted in consistently higher As release. The As desorption data followed the first-order kinetics in the early time stages of the desorption whereas at longer times the parabolic diffusion model was valid.     

Occurrence of a nitro metabolite of a defined nonylphenol isomer in soil/sewage sludge mixtures

Uniformly [14C]-ring-labeled 4-(3,5-dimethyl-3-heptyl)phenol (353-nonylphenol) is a highly relevant isomer of the technical nonylphenol mixture. We studied the sorption, desorption, and degradation of the synthesized isomer in an agricultural sandy loam at various soil/sewage sludge ratios. Sorption of 353-nonylphenol was high and differed with the amount of suspended soil in water. log Koc values, which are used to assess the risk of nonylphenol, ranged from 3.80 to 5.75. Desorption was slow and low and resulted in constant concentrations of about 15 ng/L353-nonylphenol in water after several desorption steps. In degradation studies up to 6% of the applied 353-nonylphenol in soil was volatilized; we consider this an important source of nonylphenol in the environment. With increasing amounts of sewage sludge in the soil/sewage sludge mixtures, 353-nonylphenol was stabilized, probably because of the lack of oxygen in sludge aggregates even under oxic conditions in flow-through systems. Unexpectedly, a less-polar metabolite was detected in amounts up to 40% of the applied nonylphenol after 135 days of incubation. This novel metabolite was identified as 4-(3,5-dimethyl-3-heptyl)-2-nitrophenol. This product formation might indicate the existence of novel metabolic pathways of nonylphenol in the environment.     

A novel method for determination of size resolved, submicrometer particle traffic emission factors

A novel approach to determine size-segregated particle number emission factors for traffic is presented. It was proven that using limited data sets (800-2000 samples) statistically significant emission factors from road traffic can be extracted. In this study data from four sites were used for calculating emission factors (rural and urban roadside, urban rooftop, and urban background). The measurements were performed using SMPS/DMPS (scanning or differential particle sizers) from TSI and commercial gas analyzers. Describing the particle concentration as a ratio to an exhaust trace gas, e.g. NOx, the dilution effect will be minimized. This ratio is easily compared among different studies. By knowledge of the emission factor of the chosen trace gas the emission ratio can be converted to an emission factor for particle numbers of defined particle sizes. For the presented method only one measurement site is needed, where the difference between high and low (background) traffic exposure is used. To define high and low traffic exposure, the best result was obtained using high ratio of [NO] to [NO2] and low [NOx], respectively. Emission ratios for 10-100-nm particles at two road sites, one high-speed 90-kmph rural case and one urban, slower, and more congested situation, were determined to (35 +/- 15) x 10(14) and (24 +/- 8) x 10(14) particles per mole NOx, respectively.     

Ethoxylation—a new method of separating brown-coal tar

Separating the complex mixture that makes up brown-coal tar is very difficult if it consists largely of phenols, resins and carboxylic acids. By ethoxylating the ingredients that possess active hydrogen, they become water-soluble and can easily be removed from the mixture by aqueous extraction. Hydrocarbons can then be recovered and used. The extracted ingredients are valuable raw materials for industry.