Efficient small molecule bulk heterojunction solar cells with high fill factors via pyrene-directed molecular self-assembly

Efficient organic photovoltaic (OPV) materials are constructed by attaching completely planar, symmetric end-groups to donor-acceptor electroactive small molecules. Appending C2-pyrene as the small molecule end-group to a diketopyrrolopyrrole core leads to materials with a tight, aligned crystal packing and favorable morphology dictated by π-π interactions, resulting in high power conversion efficiencies and high fill factors. The use of end-groups to direct molecular self-assembly is an effective strategy for designing high-performance small molecule OPV devices.     

The social status of aggressive students across contexts: The role of classroom status hierarchy, academic achievement, and grade.

This study tested the effects of 5 classroom contextual features on the social status (perceived popularity and social preference) that peers accord to aggressive students in late elementary school, including classroom peer status hierarchy (whether within-classroom differences in popularity are large or small), classroom academic level, and grade level as the main predictors of interest as well as classroom aggression and ethnic composition as controls. Multilevel analyses were conducted on an ethnically diverse sample of 968 fourth- and fifth-graders from 46 classrooms in 9 schools. Associations between aggression and status varied greatly from one classroom to another. Aggressive students were more popular and better liked in classrooms with higher levels of peer status hierarchy. Aggressive students had higher social status in Grade 5 than in Grade 4 and lower social preference in classrooms of higher academic level. Classroom aggression and ethnic composition did not moderate aggression–status associations. Limitations and practical implications of these findings are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Estimating the effects of 17alpha-ethinylestradiol on populations of the fathead minnow Pimephales promelas: are conventional toxicological endpoints adequate?

Environmental benchmarks have recently been proposed for several steroids including the synthetic steroid, 17alpha-ethinylestradiol (EE2). These benchmarks are based on extrapolation from studies involving long-term exposure of various fish species to EE2. One of the critical studies was a complete life-cycle experiment performed with the fathead minnow Pimephales promelas over a 289 day exposure period. The lowest observed effect concentration (LOEC) and the no observed effect concentration (NOEC) for gonad histology were 4 and 1 ng L(-1) respectively. This was because no testicular tissue could be found in any fish exposed to 4 ng L(-1). In the present paper, the survival and reproduction data from that study are reanalyzed to determine the effects of EE2 on the intrinsic rate of population growth (r = In (lambda)), a parameter of demographic importance. We estimate critical threshold concentrations with respect to r and compare these with those previously derived from conventional toxicity test summaries. Further, we assess the influence of individual variability on threshold estimates using a combination of bootstrap and regression approaches, together with a suite of perturbation analyses. These yield ErC100 values (the concentration estimated to reduce intrinsic growth rate to zero) of 3.11 ng L(-1) (linear model) and 3.41 ng L(-1) (quadratic model), comparable with a maximum acceptable toxicant concentration (MATC) of 2 ng L(-1) for feminization of exposed fish calculated by Laenge et al. Our results indicate that reduction in population growth rate with increasing concentration occurred more through EE2 acting to reduce fertility than survival rates. The significance of these summary statistics when deriving environmental benchmarks for steroid estrogens is discussed in the context of affording protection to populations following long-term exposure.     

Antimicrobial activity of foodborne Paenibacillus and Bacillus spp. against Clostridium botulinum

The saprophytic Paenibacillus and Bacillus spp. found in cooked chilled foods may have an effect on the growth of Clostridium botulinum, a major microbiological hazard, especially for pasteurized vacuum-packaged products. Culture supernatants of 200 strains of Paenibacillus and Bacillus strains isolated from commercial cooked chilled foods containing vegetables were screened for activity against C. botulinum type A, proteolytic type B, and type E strains in a well diffusion assay. Nineteen strains were positive against C. botulinum. Among those, seven Paenibacillus polymyxa strains showed the highest antibotulinal activity and the largest antimicrobial spectrum against C. botulinum strains. The antibotulinal activity was evaluated throughout the growth of a representative strain of the positive P. polymyxa strains. The antimicrobial activity was detected in the culture supernatant from late-log/early stationary phase of the bacteria, which occurred after 7 to 10 days of incubation at 10 degrees C and after 2 to 3 days at 20 degrees C in nutrient broth and in vegetable purées under aerobic or anaerobic conditions. In co-cultures with the positive strain of P. polymyxa in nutrient broth and vegetable purées, a C. botulinum type E strain was inhibited whenever P. polymyxa reached stationary phase and produced its antimicrobial activity before C. botulinum began its exponential growth phase. The antimicrobial activity of P. polymyxa against C. botulinum was attributed to the production of antimicrobial peptides resistant to high temperature and acidity. Other gram-positive and -negative bacteria (Escherichia coli, Streptococcus mutans, Leuconostoc mesenteroides, and Bacillus subtilis) were also sensitive to these antimicrobial peptides.     

[C] Milk, urine and faeces excretion kinetics in lactating goats after an oral administration of [C]polycyclic aromatic hydrocarbons

The aim of this work was to characterize phenanthrene, pyrene, benzo(a)pyrene and TCDD transfer to milk, urine and faeces in lactating goats after a single oral ingestion (2.5 10⁶ Bq) of [¹⁴C]phenanthrene, [¹⁴C]pyrene, [¹⁴C]benzo[a]pyrene or [¹⁴C]2,3,7,8-TCDD.

Seven hours after [¹⁴C] PAHs oral ingestion, a radioactivity peak was detected in plasma for all compounds studied. Regarding excretion routes, three specific types of behaviour were noticed: 2,3,7,8-TCDD was mainly excreted in milk (7.8%) and a large part of radioactivity ingested remained in the organism (71.2%). Phenanthrene and pyrene presented a similar behaviour, with a low milk transfer (1.6% and 1.9%, respectively) and a high excretion through urine (40.4% and 11.4%, respectively) suggesting their metabolization. Benzo[a]pyrene was poorly absorbed (88% of the ingested part of this compound was detected in faeces) and radioactivity due to benzo[a]pyrene was not significantly detected in milk (0.2%).     

Black carbon from the Mississippi River: quantities,sources, and potential implications for the global carbon cycle

Black carbon (BC) may be a major component of riverine carbon exported to the ocean, but its flux from large rivers is unknown. Furthermore, the global distribution of BC between natural and anthropogenic sources remains uncertain. We have determined BC concentrations in suspended sediments of the Mississippi River, the 7th largest river in the world in terms of sediment and water discharge, during high flow and low flow in 1999. The 1999 annual flux of BC from the Mississippi River was 5 x 10(-4) petagrams (1 Pg = 10(15) g = 1 gigaton). We also applied a principal components analysis to particulate-phase high molecular weight polycyclic aromatic hydrocarbon isomer ratios in Mississippi River suspended sediments. In doing so, we determined that approximately 27% of the BC discharged from the Mississippi River in 1999 originated from fossil fuel combustion (coal and smelter-derived combustion), implicating fluvial BC as an important source of anthropogenic BC contamination into the ocean. Using our value for BC flux and the annual estimate for BC burial in ocean sediments, we calculate that, in 1999, the Mississippi River discharged approximately 5% of the BC buried annually in the ocean. These results have important implications, not only for the global carbon cycle but also for the fluvial discharge of particulate organic contaminants into the world's oceans.     

A current review of structure,functional properties,and industrial applications of pulse starches for value-added utilization

Pulse crops have received growing attention from the agri-food sector because they can provide advantageous health benefits and offer a promising source of starch and protein. Pea, lentil, and faba bean are the three leading pulse crops utilized for extracting protein concentrate/isolate in food industry, which simultaneously generates a rising volume of pulse starch as a co-product. Pulse starch can be fractionated from seeds using dry and wet methods. Compared with most commercial starches, pea, lentil, and faba bean starches have relatively high amylose contents, longer amylopectin branch chains, and characteristic C-type polymorphic arrangement in the granules. The described molecular and granular structures of the pulse starches impart unique functional attributes, including high final viscosity during pasting, strong gelling property, and relatively low digestibility in a granular form. Starch isolated from wrinkled pea—a high-amylose mutant of this pulse crop—possesses an even higher amylose content and longer branch chains of amylopectin than smooth pea, lentil, and faba bean starches, which make the physicochemical properties and digestibility of the former distinctively different from those of common pulse starches. The special functional properties of pulse starches promote their applications in food, feed, bioplastic and other industrial products, which can be further expanded by modifying them through chemical, physical and/or enzymatic approaches. Future research directions to increase the fractionation efficiency, improve the physicochemical properties, and enhance the industrial utilization of pulse starches have also been proposed. The comprehensive information covered in this review will be beneficial for the pulse industry to develop effective strategies to generate value from pulse starch.