Donor–Acceptor–Acceptor's Molecules for Vacuum‐Deposited Organic Photovoltaics with Efficiency Exceeding 9%

Three vacuum‐deposited donor–acceptor–acceptor (d–a–a') small molecule donors are studied with different side chains attached to an asymmetric heterotetracene donor block for use in high efficiency organic photovoltaics (OPVs). The donor with an isobutyl side chain yields the highest crystal packing density compared to molecules with 2‐ethylhexyl or n‐butyl chains, leading to the largest absorption coefficient and short circuit current in an OPV. It also exhibits a higher fill factor, consistent with its preferred out‐of‐plane molecular π–π stacking arrangement that facilitates charge transport in the direction perpendicular to the substrate. A power conversion efficiency of 9.3 ± 0.5% is achieved under 1 sun intensity, AM 1.5 G simulated solar illumination, which is significantly higher than 7.5 ± 0.4% of the other two molecules. These results indicate that side chain modification of d–a–a' small molecules offers an effective approach to control the crystal packing configuration, thereby improving the device performance.     

The effects of calling song spacing and intensity on the attraction of flying crickets (orthoptera: Goryllidae: Nemobiinae)

Previous studies have shown that sexually signaling males across different taxa show stereotyped spacing behavior that may be related to aspects of their signals, such as intensity. However, few studies have shown that the separation between signaling males affects their relative attractiveness. Using two sound traps broadcasting the calling song of the cricketEunemobius carolinus, we show that the separation, relative intensity, and absolute intensity of the calling songs influence calling song attractiveness. For calling songs separated by 5 m, the proportion of individuals attracted to the higher intensity song increased as the relative intensity difference of the two songs increased from 3 to 6 dB. For calling songs that differed by 6 dB, relative attraction to the less intense song decreased with decreasing song separation. These two results are consistent with the predictions of a model (Forrest and Raspet, 1994) that suggests that dense spacing is more costly for less powerful singers and that this cost increases with increasing differences in relative intensity. When the relative intensity of the songs was held constant (6 dB), we found that discrimination between songs decreases as the song absolute intensity increases. In particular, a greater proportion of individuals was attracted to the high-intensity song when the songs were broadcast at 103 and 97 dB than when the songs were broadcast at 109 and 103 dB. Unlike mammals and birds, the ability ofE. carolinus to discriminate between songs that differ in intensity may decrease as the absolute intensity increases. This may mean that females are less discriminating when they are closer to singing males.     

The spread of topically-applied pyrethrin I from the cuticle to the central nervous system of the cockroach Periplaneta americana

Penetration of topically-applied pyrethrin I into adult male American cockroaches (Periplaneta americana L.) and its subsequent distribution within the insects was studied microchemically and biologically. After applying an LD95 (0.5 g per insect), pyrethrin I was lost from the surface of the insects at a rate diminishing with time; 20% of the dose applied penetrated during the first hour, but elimination limited the amount found inside the insects to a maximum of 13%. The amount inside the insects increased for an hour after dosing, when symptoms of poisoning had become severe, but then remained steady until the end of the test, 48 hrs after dosing.Pyrethrin I sorbs strongly but reversibly on insect solids from aqueous solution, and at equilibrium is distributed between solids and solution in the ratio 3 × 10⁴: 1. This ratio would give a concentration of only 4 × 10^–11 M of pyrethrin I in the haemolymph of insects poisoned with an LD95 of the insecticide, but solids in the haemolymph would increase its pyrethrin I content and speed the spread of the insecticide from cuticle to nervous system. Chemical tests able to detect pyrethrin I at concentrations of 2×10^–8 M failed to show its presence in the haemolymph of poisoned cockroaches, but the haemolymph caused symptoms resembling those of pyrethroid poisoning when applied to nerve preparations from normal cockroaches.Although pyrethrin I at 4 × 10^–11 M in the haemolymph of cockroaches treated topically with LD95s of the insecticide seems too dilute to have produced the symptoms observed in their nervous systems, the results of additional tests did not support the alternative suggestion that the insecticide reached the nervous system by spreading over the cuticle and through the tracheal system. Larger concentrations of pyrethrin I occurring locally in the haemolymph near the nervous system during the early stages of poisoning may explain the anomaly.

---

Résumé La pénétration d'une application topique de pyrethrine I chez le mâle adulte de Periplaneta americana et sa distribution ultérieure dans l'organisme est étudiée microchimiquement et biologiquement. Après application d'une dose égale à la DL 95 (0,5 g par insecte), la pyrethrine I est absorbée à la surface de l'insecte à un taux décroissant avec le temps; 20% de la dose appliquée pénètre durant la 1ère heure, mais l'élimination limite la quantité trouvée dans l'organisme à un maximum de 13%. La quantité trouvée dans l'organisme s'accroît pendant la 1ère heure après l'intoxication, quand les symptômes de l'intoxication deviennent importants, puis reste stationnaire jusqu'à la fin du test, soit 48 heures après l'intoxication.La pyrethrine I s'absorbe fortement mais réversiblement sur la phase solide de l'insecte, à partir de la solution aqueuse et le coefficient de partition est de 3×10⁴: 1. Ce coefficient donnarait une concentration de pyrethrine I de seulement 4 × 10^–11 M dans l'hémolymphe des insectes intoxiqués à la DL 95, mais la phase solide de l'hémolymphe augmenterait sa teneur en pyrethrine I et accélérerait la vitesse de pénétration de l'insecticide, de la cuticule vers le système nerveux. Des tests chimiques capables de déceler la pyrethrine I à la concentration de 2×10^–8 M n'ont pu établir sa présence dans l'hémolymphe des blattes intoxiquées, mais cette hémolymphe provoque des symptômes analogues à ceux de l'intoxication par les pyrethrines, quand elle est appliquée à des préparations nerveuses de blattes nonintoxiquées.Quoique la pyrethrine I à la concentration de 4 × 10^–11 M dans l'hémolymphe de blattes traitées localement à la DL 95 de cet insecticide, semble trop diluée pour produire les symptômes observés dans le système nerveux, des résultats supplémentaires n'ont pas autorisé une autre hypothèse, à savoir que l'insecticide atteindrait le système nerveux via la cuticule et le système trachéen. Des concentrations plus fortes de pyrethrine I, localisées près du système nerveux pendant les premiers stades de l'intoxication pourraient expliquer cette anomalie.

     

Molecular markers for adult plant leaf rust resistance gene <Emphasis Type="Italic">Lr48</Emphasis> in wheat

Leaf rust of wheat, caused by Puccinia triticina, is an important disease throughout the world. The adult plant leaf rust resistance gene Lr48 reported in CSP44 was previously mapped in chromosome 2B, but the marker–gene association was weak. In this study, we confirmed the location of Lr48 to be in the short arm of chromosome 2B and identified closely linked markers suitable for use in breeding. The CSP44/WL711 recombinant inbred line (RIL) population (90 lines) showed monogenic segregation for Lr48. Twelve resistant and 12 susceptible RILs were used for selective genotyping using an iSelect 90K Infinium SNP assay. Closely linked SNPs were converted into Kompetitive allele-specific primers (KASP) and tested on the parental lines. KASP markers giving clear clusters for alternate genotypes were assayed on the entire RIL population. SNP markers IWB31002, IWB39832, IWB34324, IWB72894 and IWB36920 co-segregated with Lr48 and the marker IWB70147 was mapped 0.3 cM proximal to this gene. Closely linked KASP markers were tested on a set of Australian and Nordic wheat genotypes. The amplification of SNP alleles alternate to those linked with Lr48 in the majority of the Australian and Nordic wheat genotypes demonstrated the usefulness of these markers for marker-assisted pyramiding of Lr48 with other rust resistance genes.     

Combined monte carlo and molecular dynamics simulation of fully hydrated dioleyl and palmitoyl-oleyl phosphatidylcholine lipid bilayers

We have applied a new equilibration procedure for the atomic level simulation of a hydrated lipid bilayer to hydrated bilayers of dioleyl-phosphatidylcholine (DOPC) and palmitoyl-oleyl phosphatidylcholine (POPC). The procedure consists of alternating molecular dynamics trajectory calculations in a constant surface tension and temperature ensemble with configurational bias Monte Carlo moves to different regions of the configuration space of the bilayer in a constant volume and temperature ensemble. The procedure is applied to bilayers of 128 molecules of POPC with 4628 water molecules, and 128 molecules of DOPC with 4825 water molecules. Progress toward equilibration is almost three times as fast in central processing unit (CPU) time compared with a purely molecular dynamics (MD) simulation. Equilibration is complete, as judged by the lack of energy drift in 200-ps runs of continuous MD. After the equilibrium state was reached, as determined by agreement between the simulation volume per lipid molecule with experiment, continuous MD was run in an ensemble in which the lateral area was restrained to fluctuate about a mean value and a pressure of 1 atm applied normal to the bilayer surface. Three separate continuous MD runs, 200 ps in duration each, separated by 10,000 CBMC steps, were carried out for each system. Properties of the systems were calculated and averaged over the three separate runs. Results of the simulations are presented and compared with experimental data and with other recent simulations of POPC and DOPC. Analysis of the hydration environment in the headgroups supports a mechanism by which unsaturation contributes to reduced transition temperatures. In this view, the relatively horizontal orientation of the unsaturated bond increases the area per lipid, resulting in increased water penetration between the headgroups. As a result the headgroup-headgroup interactions are attenuated and shielded, and this contributes to the lowered transition temperature.     

L-770,644: a potent and selective human beta3 adrenergic receptor agonist with improved oral bioavailability.

L-770,644 (9c) is a potent and selective agonist of the human beta3 adrenergic receptor (EC50 = 13 nM). It shows good oral bioavailability in both dogs and rats (%F = 27), and is a full agonist for glycerolemia in the rhesus monkey (ED50 = 0.21 mg/kg). Based on its desirable in vitro and in vivo properties, L-770,644 was chosen for further preclinical evaluation.     

Fine mapping of the chromosome 5B region carrying closely linked rust resistance genes <Emphasis Type="Italic">Yr47</Emphasis> and <Emphasis Type="Italic">Lr52</Emphasis> in wheat

Key message

Fine mapping of Yr47 and Lr52 in chromosome arm 5BS of wheat identified close linkage of the marker sun180 to both genes and its robustness for marker-assisted selection was demonstrated.

Abstract

The widely effective and genetically linked rust resistance genes Yr47 and Lr52 have previously been mapped in the short arm of chromosome 5B in two F₃ populations (Aus28183/Aus27229 and Aus28187/Aus27229). The Aus28183/Aus27229 F₃ population was advanced to generate an F₆ recombinant inbred line (RIL) population to identify markers closely linked with Yr47 and Lr52. Diverse genomic resources including flow-sorted chromosome survey sequence contigs representing the orthologous region in Brachypodium distachyon, the physical map of chromosome arm 5BS, expressed sequence tags (ESTs) located in the 5BS6-0.81-1.00 deletion bin and resistance gene analog contigs of chromosome arm 5BS were used to develop markers to saturate the target region. Selective genotyping was also performed using the iSelect 90 K Infinium wheat SNP assay. A set of SSR, STS, gene-based and SNP markers were developed and genotyped on the Aus28183/Aus27229 RIL population. Yr47 and Lr52 are genetically distinct genes that mapped 0.4 cM apart in the RIL population. The SSR marker sun180 co-segregated with Lr52 and mapped 0.4 cM distal to Yr47. In a high resolution mapping population of 600 F₂ genotypes Yr47 and Lr52 mapped 0.2 cM apart and marker sun180 was placed 0.4 cM distal to Lr52. The amplification of a different sun180 amplicon (195 bp) than that linked with Yr47 and Lr52 (200 bp) in 204 diverse wheat genotypes demonstrated its robustness for marker-assisted selection of these genes.

     

Foliage affects colour preference in bumblebees (<Emphasis Type="Italic">Bombus impatiens</Emphasis>): a test in a three-dimensional artificial environment

Red flowers are a defining character of the bird-pollination syndrome. Birds do not, however, innately prefer red, suggesting that rather than attracting birds, red flowers may serve to exclude other visitors (e.g., bumblebees). Bees are sometimes considered “blind” to red, but studies have in fact documented both blue and red preferences in various bee species. These mixed results may be an effect of overly simplistic lab settings. We hypothesized that bees might readily locate red flowers in a simple laboratory environment, but struggle to find the same flowers in a complex, foliated setting. We tested the effects of environmental complexity on visitation to red and blue artificial flowers and on the foraging rate of captive worker bumblebees (Bombus impatiens). Bees made significantly fewer visits to red flowers when foraging in a complex environment with artificial green foliage, suggesting that red becomes harder to locate in this context than in a simple, leafless environment. Bees also foraged more slowly, on average, in the complex environment, although the difference was apparent only among experienced bees. Our findings provide a possible explanation for previous laboratory tests finding no colour preference in bumblebees. This “contextual colour-blindness” of bees supports the hypothesis that red evolved as a mechanism for plants to avoid visitation by bees, favouring bird pollination instead.