Absorption spectra of poly-N-vinylcarbazole derivatives by experiment and simulation

Geometry molecular optimization and quantum chemical simulations of absorption spectra for newly synthesized poly-N-vinylcarbazole derivatives were performed using a semi-empirical approach. The studied polymers were modified by changing the positions of the carbazole group with respect to the polymer backbone. The absorption spectra were calculated for different numbers of PNVK monomers. A sufficient agreement between the calculated and experimentally measured spectra was observed. A change of the red shift absorption with respect to the blue shift was observed for cases when the number of monomers was higher than 4. The theoretical simulations indicate that this behavior is a consequence of the specific molecular structure of the considered molecules. The results demonstrate the potential of combined simulation and experimental studies in materials engineering and searching of new electro-luminescent materials

Proglucagon signalling in the rat dorsomedial hypothalamus - physiology and high-fat diet-mediated alterations

A relatively new pharmacological target in obesity treatment has been the preproglucagon (PPG) signalling, predominantly with glucagon-like peptide (GLP) 1 receptor agonists. As far as the PPG role within the digestive system is well recognised, its actions in the brain remain understudied. Here, we investigated PPG signalling in the Dorsomedial Hypothalamus (DMH), a structure involved in feeding regulation and metabolism, using in situ hybridisation, electrophysiology, and immunohistochemistry. Our experiments were performed on animals fed both control, and high-fat diet (HFD), uncovering HFD-mediated alterations. First, sensitivity to exendin-4 (Exn4, a GLP1R agonist) was shown to increase under HFD, with a higher number of responsive neurons. The amplitude of the response to both Exn4 and oxyntomodulin (Oxm) was also altered, diminishing its relationship with the cells' spontaneous firing rate. Not only neuronal sensitivity, but also GLP1 presence, and therefore possibly release, was influenced by HFD. Immunofluorescent labelling of the GLP1 showed changes in its density depending on the metabolic state (fasted/fed), but this effect was eliminated by HFD feeding. Interestingly, these dietary differences were absent after a period of restricted feeding, allowing for an anticipation of the alternating metabolic states, which suggests possible prevention of such outcome

Predicting growth and development of pigeonpea: leaf area development

Relationships are developed that describe the processes of node production, leaf appearance and senescence, and leaf size in pigeonpea in relation to temperature, plant density and maturity type. The rate of node production until owering in relation to thermal time was found to be unaffected by season and plant density in the range of 4±33 plants mÿ2. Maturity type did not affect the rate of node production on the main stem or the rate of appearance of leaves on the plant. The rate of senescence of main-stem nodes in relation to thermal time was unaffected by plant density and growth duration. The functions developed in this paper can be used to predict the temporal changes in leaf area development in crop growth models

Comparative physical maps derived from BAC end sequences of tilapia (Oreochromis niloticus)

Background: The Nile tilapia is the second most important fish in aquaculture. It is an excellent laboratory model, and is closely related to the African lake cichlids famous for their rapid rates of speciation. A suite of genomic resources has been developed for this species, including genetic maps and ESTs. Here we analyze BAC endsequences to develop comparative physical maps, and estimate the number of genome rearrangements, between tilapia and other model fish species. Results: We obtained sequence from one or both ends of 106,259 tilapia BACs. BLAST analysis against the genome assemblies of stickleback, medaka and pufferfish allowed identification of homologies for approximately 25,000 BACs for each species. We calculate that rearrangement breakpoints between tilapia and these species occur about every 3 Mb across the genome. Analysis of 35,000 clones previously assembled into contigs by restriction fingerprints allowed identification of longer-range syntenies. Conclusions: Our data suggest that chromosomal evolution in recent teleosts is dominated by alternate loss of gene duplicates, and by intra-chromosomal rearrangements (~one per million years). These physical maps are a useful resource for comparative positional cloning of traits in cichlid fishes. The paired BAC end sequences from these clones will be an important resource for scaffolding forthcoming shotgun sequence assemblies of the tilapia genome. (Résumé d'auteur

The Function of Anal Fin Egg-Spots in the Cichlid Fish Astatotilapia burtoni

Color and pigmentation patterns of animals are often targets of sexual selection because of their role in communication. Although conspicuous male traits are typically implicated with intersexual selection, there are examples where sex-specific displays play a role in an intrasexual context, e.g. when they serve as signals for aggression level and/or status. Here, we focus on the function of a conspicuous male ornament in the most species-rich tribe of cichlid fishes, the haplochromines. A characteristic feature of these ca. 1500 species are so-called egg-spots in form of ovoid markings on the anal fins of males, which are made up of carotenoid based pigment cells. It has long been assumed that these yellow, orange or reddish egg-spots play an important role in the courtship and spawning behavior of these maternal mouth-brooding fishes by mimicking the eggs of a conspecific female. The exact function of egg-spots remains unknown, however, and there are several hypotheses about their mode of action. To uncover the function of this cichlid-specific male ornament, we used female mate choice experiments and a male aggression test in the haplochromine species Astatotilapia burtoni. We manipulated the number and arrangement of egg-spots on the anal fins of males, or removed them entirely, and tested (1) female preference with visual contact only using egg-traps, (2) female preference with free contact using paternity testing with microsatellites and (3) male aggression. We found that females did not prefer males with many egg-spots over males with fewer egg-spots and that females tended to prefer males without egg-spots over males with egg-spots. Importantly, males without egg-spots sired clutches with the same fertilization rate as males with egg-spots. In male aggression trials, however, males with fewer egg-spots received significantly more attacks, suggesting that egg-spots are an important signal in intrasexual communication

(Photo)physical properties of new molecular glasses end-capped with thiophene rings composed of diimide and imine units

New symmetrical arylene bisimide derivatives formed by using electron-donating-electron-accepting systems were synthesized. They consist of a phthalic diimide or naphthalenediimide core and imine linkages and are end-capped with thiophene, bithiophene, and (ethylenedioxy)thiophene units. Moreover, polymers were obtained from a new diamine, N,N′-bis(5- aminonaphthalenyl)naphthalene-1,4,5,8-dicarboximide and 2,5- thiophenedicarboxaldehyde or 2,2′-bithiophene-5,5′-dicarboxaldehyde. The prepared azomethine diimides exhibited glass-forming properties. The obtained compounds emitted blue light with the emission maximum at 470 nm. The value of the absorption coefficient was determined as a function of the photon energy using spectroscopic ellipsometry. All compounds are electrochemically active and undergo reversible electrochemical reduction and irreversible oxidation processes as was found in cyclic voltammetry and differential pulse voltammetry (DPV) studies. They exhibited a low electrochemically (DPV) calculated energy band gap (Eg) from 1.14 to 1.70 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels and Eg were additionally calculated theoretically by density functional theory at the B3LYP/6-31G(d,p) level. The photovoltaic properties of two model compounds as the active layer in organic solar cells in the configuration indium tin oxide/poly(3,4-(ethylenedioxy)thiophene):poly(styrenesulfonate)/active layer/Al under an illumination of 1.3 mW/cm2 were studied. The device comprising poly(3-hexylthiophene) with the compound end-capped with bithiophene rings showed the highest value of Voc (above 1 V). The conversion efficiency of the fabricated solar cell was in the range of 0.69-0.90%

Nestmate relatedness in the Australian ant myrmecia pyriformis smith, 1858 (Hymenoptera: Formicidae)

We investigated the genetic structure of 19 colonies of the myrmeciine ant Myrmecia pyriformis SMITH, 1858, using five microsatellite loci. Nestmate relatedness of b = 0.51 +/- 0.04 significantly deviated from the theoretical value of 0.75, which is expected in a monogynous monandrous social system. The occurrence of multiple mating by queens was the most likely explanation in the majority of colonies, and the effective number of male mates was estimated to be 2.60. However, multiple female reproductives were also inferred in some cases. The results correspond well both to observations on promiscuous mating behaviour in the winged sexuals of some species of Myrmecia and to the occurrence of gamergates (mated workers) in M. pyriformis. The finding of high levels of polyandry in a species with totipotent workers is discussed with regard to the evolution of eusociality

Polyandry and colony genetic structure in the primitive and Nothomyrmecia macrops

The Australian endemic ant Nothomyrmecia macrops is considered one of the most ‘primitive’ among living ants. We investigated the genetic structure of colonies to determine queen mating frequencies and nestmate relatedness. An average of 18.8 individuals from each of 32 colonies, and sperm extracted from 34 foraging queens, were genotyped using five highly variable microsatellite markers. Queens were typically singly (65%) or doubly mated (30%), but triple mating (5%) also occurred. The mean effective number of male mates for queens was 1.37. No relationship between colony size and queen mate number was found. Nestmate workers were related by b=0.61 ± 0.03, significantly above the threshold under Hamilton’s rule over which, all else being equal, altruistic behaviour persists, but queens and their mates were unrelated. In 25% of the colonies we detected a few workers that could not have been produced by the resident queen, although there was no evidence for worker reproduction. Polyandry is for the first time recorded in a species with very small mature colonies, which is inconsistent with the sperm-limitation hypothesis for the mediation of polyandry levels. Facultative polyandry is therefore not confined to the highly advanced ant genera, but may have arisen at an early stage in ant social evolution

Chronostratygraficzna i głębokościowa zmienność porowatości i wytrzymałości węgli w Górnośląskim Zagłębiu Węglowym

This article presents values of porosity and compression strength of hard coals from the area of the Upper Silesian Coal Basin. The change of the stage of carbonification, which results from conversion of coal substance in the process of coalification, is a source of many changes in the structure of coal. These changes exert influence on values of physical parameters, including the values of porosity and strength. Porosity and compression strength change with the degree of carbonification, a result of the depth of deposition. This study determined the values of effective porosity of coals and their strength considering the age chronology of coal seams and the depth of their occurrence. It examined coals of the Cracow Sandstone Series, the Mudstone Series, the Upper Silesian Sandstone Series, and the Paralic Series from depths ranging from about 350 m to 1200 m. The authors have shown that effective porosity of the Upper Silesian coals changes for particular stratigraphic groups and assumes values from a few to a dozen or so per cent, while compression strength from several to several dozen megapascals. It has been observed, from a chronostratigraphic perspective, that there is a shifting of the upper and lower limits of intervals of porosity variations towards higher values for younger coals. With the increase in compression strength, value of porosity in particular stratigraphic groups generally decreases. However, no regular changes were observed inmean, uniaxial compressive strength with the increase in the age of subsequent stratigraphic groups. On the other hand, for bright coal and semi-bright coal, a visible decrease in compression strength with the depth of deposition of strata was observed.W artykule przedstawiono wartości porowatości i wytrzymałości na ściskanie węgli kamiennych z obszaru Górnośląskiego Zagłębia Węglowego. Zmiana stopnia uwęglenia, który wynika z przemian materii węglowej w procesie uwęglenia, jest źródłem wielu zmian w strukturze węgla. Zmiany te wpływają na wartość parametrów fizycznych, w tym na wartość porowatości i wytrzymałości. Porowatość i wytrzymałość na ściskanie zmieniają się ze stopniem uwęglenia, który wynika z głębokości zalegania. Przedstawione w artykule wartości porowatości efektywnej węgli i ich wytrzymałość zostały opracowane z uwzględnieniem chronologii wiekowej pokładów węgla i głębokości ich występowania. Przebadano węgle krakowskiej serii piaskowcowej, serii mułowcowej, górnośląskiej serii piaskowcowej i serii paralicznej, z głębokości od około 350 m do około 1200 m. Autorzy wykazali, że porowatość efektywna węgli górnośląskich zmienia się dla poszczególnych grup stratygraficznych i przyjmuje wartości od kilku do kilkunastu procent a wytrzymałość na ściskanie od kilkunastu do kilkudziesięciu megapaskali. Zaobserwowano, w ujęciu chronostratygraficznym, przesuwanie się górnej i dolnej granicy przedziałów zmienności porowatości w kierunku wyższych wartości dla węgli młodszych. Ze wzrostem wytrzymałości na ściskanie wartość porowatości w poszczególnych grupach stratygraficznych generalnie maleje. Nie zaobserwowano natomiast regularnych zmian średniej wytrzymałości na jednoosiowe ściskanie ze wzrostem wieku kolejnych grup stratygraficznych. Dla węgla błyszczącego i półbłyszczącego wykazano natomiast wyraźny spadek wytrzymałości na ściskanie z głębokością zalegania pokładów