| 1. |
- Fabiano, Simone, et al.
(författare)
-
Poly(ethylene imine) impurities induce n-doping reaction in organic (semi)conductors
- 2014
-
Ingår i: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 26:34, s. 6000-6006
-
Tidskriftsartikel (refereegranskat)abstract
- Volatile impurities contained in polyethyleneimine (PEI), and identified as ethyleneimine dimers and trimers, are reported. These N-based molecules show a strong reducing character, as demonstrated by the change in electrical conductivity of organic (semi) conductors exposed to the PEI vapor. The results prove that electron transfer rather than a dipole effect at the electrode interface is the origin of the work-function modification by the PEI-based layers.
|
|
| 2. |
- Gekière, Antoine, et al.
(författare)
-
Poison or Potion : Effects of Sunflower Phenolamides on Bumble Bees and Their Gut Parasite
- 2022
-
Ingår i: Biology. - : MDPI AG. - 2079-7737. ; 11:4
-
Tidskriftsartikel (refereegranskat)abstract
- Specific floral resources may help bees to face environmental challenges such as parasite infection, as recently shown for sunflower pollen. Whereas this pollen diet is known to be unsuitable for the larval development of bumble bees, it has been shown to reduce the load of a trypanosomatid parasite (Crithidia bombi) in the bumble bee gut. Recent studies suggested it could be due to phenolamides, a group of compounds commonly found in flowering plants. We, therefore, decided to assess separately the impacts of sunflower pollen and its phenolamides on a bumble bee and its gut parasite. We fed Crithidia-infected and -uninfected microcolonies of Bombus terrestris either with a diet of willow pollen (control), a diet of sunflower pollen (natural diet) or a diet of willow pollen supplemented with sunflower phenolamides (supplemented diet). We measured several parameters at both microcolony (i.e., food collection, parasite load, brood development and stress responses) and individual (i.e., fat body content and phenotypic variation) levels. As expected, the natural diet had detrimental effects on bumble bees but surprisingly, we did not observe any reduction in parasite load, probably because of bee species-specific outcomes. The supplemented diet also induced detrimental effects but by contrast to our a priori hypothesis, it led to an increase in parasite load in infected microcolonies. We hypothesised that it could be due to physiological distress or gut microbiota alteration induced by phenolamide bioactivities. We further challenged the definition of medicinal effects and questioned the way to assess them in controlled conditions, underlining the necessity to clearly define the experimental framework in this research field.
|
|
| 3. |
- Sculfort, Ombeline, et al.
(författare)
-
Specialized Metabolites in Floral Resources : Effects and Detection in Buff-Tailed Bumblebees
- 2021
-
Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- The selection of appropriate food resources by bees is a critical aspect for the maintenance of their populations, especially in the current context of global change and pollinator decline. Wild bees have a sophisticated ability to forage selectively on specific resources, and can assess the quality of pollen using contact chemosensory perception (taste). While numerous studies have investigated the detection of pollen macronutrients in bees and their impact on bee health and reproductive success, only a few studies have described the gustatory responses of bees toward specialized metabolites. In addition, these studies mostly focused on the response to nectar and neglected pollen, which is the main food resource for both bee imagines and larvae. Whether bees have the ability to detect specialized toxic metabolites in pollen and then rapidly adapt their foraging behavior to avoid them is very little studied. In this study, we tested whether pollen specialized metabolites affect bumblebees at both the micro-colony and individual levels (i.e., bioassays using supplemented pollen), and whether foragers detect these specialized metabolites and potentially display an avoidance behavior (i.e., preference tests using supplemented syrup). Bumblebees were fed with either amygdalin-, scopolamine- or sinigrin-supplemented pollen diets in ratios that mimic 50%, 100%, and 200% of naturally occurring concentrations. We found no effect of these specialized metabolites on resource collection, reproductive success and stress response at the micro-colony level. At the individual level, bumblebees fed on 50%-amygdalin or 50%-scopolamine diets displayed the highest scores for damage to their digestive systems. Interestingly, during the preference tests, the solution with 50%-scopolamine displayed a phagostimulatory activity, whereas solution with 50%-amygdalin had a deterrent effect and could trigger an active avoidance behavior in bumblebees, with a faster proboscis retraction. Our results suggest that regulation of toxin intake is not as well-established and effective as the regulation of nutrient intake in bees. Bees are therefore not equally adapted to all specialized pollen metabolites that they can come into contact with.
|
|
| 4. |
- Tassignon, Benjamin, et al.
(författare)
-
Site Selectivity of Peptoids as Azobenzene Scaffold for Molecular Solar Thermal Energy Storage
- 2023
-
Ingår i: Chemistry - A European Journal. - 1521-3765 .- 0947-6539. ; 29:70
-
Tidskriftsartikel (refereegranskat)abstract
- Storing solar energy is a key challenge in modern science. MOlecular Solar Thermal (MOST) systems, in particular those based on azobenzene switches, have received great interest in the last decades. The energy storage properties of azobenzene (t1/2<4 days; ΔH~270 kJ/kg) must be improved for future applications. Herein, we introduce peptoids as programmable supramolecular scaffolds to improve the energy storage properties of azobenzene-based MOST systems. We demonstrate with 3-unit peptoids bearing a single azobenzene chromophore that dynamics of the MOST systems can be tuned depending on the anchoring position of the photochromic unit on the macromolecular backbone. We measured a remarkable increase of the half-life of the metastable form up to 14 days at 20 °C for a specific anchoring site, significantly higher than the isolated azobenzene moiety, thus opening new perspectives for MOST development. We also highlight that liquid chromatography coupled to mass spectrometry does not only enable to monitor the different stereoisomers during the photoisomerization process as traditionally done, but also allows to determine the thermal back-isomerization kinetics.
|
|
| 5. |
- Tran Nguyen, Ha, et al.
(författare)
-
Novel regioregular poly(3-hexylthiophene)-based polycationic block copolymers
- 2011
-
Ingår i: POLYMER BULLETIN. - : Springer Science Business Media. - 0170-0839 .- 1436-2449. ; 66:1, s. 51-64
-
Tidskriftsartikel (refereegranskat)abstract
- Regioregular poly(3-hexylthiophene) has been successfully incorporated into various poly(N,N-dimethylamino-2-ethyl methacrylate)-based block copolymers, i.e., P3HT-b-PDMAEMA, via Grignard metathesis (GRIM) method and atom transfer radical polymerization (ATRP) reactions. The structure of the diblock copolymers was fully confirmed by FT-IR, H-1 NMR spectroscopy, gel permeation chromatography (GPC), and ultraviolet-visible spectroscopy (UV-vis). The recovered copolymers could be treated by protonation of the pending tertiary amine functions and depending on the relative content in PDMAEMA, the copolymers could be solubilized in more polar solvents where P3HT alone proved to be totally insoluble.
|
|
