Speciation leads to divergent methylmercury accumulation in sympatric whitefish

Central European lake whitefish (Coregonus spp.) colonized Swiss lakes following the last glacial retreat and have undergone rapid speciation and adaptive radiation. Up to six species have been shown to coexist in some lakes, and individual species occupy specific ecological niches and have distinct feeding and reproductive ecologies. We studied methylmercury (MeHg) accumulation in sympatric whitefish species from seven Swiss lakes to determine if ecological divergence has led to different rates of MeHg bioaccumulation. In four of seven lakes, sympatric species had distinctly different MeHg levels, which varied by up to a factor of two between species. Generally, species with greater MeHg levels were smaller in body size and planktivorous, and species with lower MeHg were larger and benthivorous. While modest disparities in trophic position between species might be expected a priori to explain the divergence in MeHg, δ15N of bulk tissue did not correlate with fish MeHg in five of seven lakes. Results of a nested ANCOVA analysis across all lakes indicated that only two factors (species, lake) explained substantial portions of the variance, with species accounting for more variance (52%) than inter-lake differences (32%). We suggest that differences in MeHg accumulation were likely caused by diverging metabolic traits between species, such as differences in energy partitioning between anabolism and catabolism, potentially interacting with species-specific prey resource utilization. These results indicate substantial variability in MeHg accumulation between closely related fish species, illustrating that ecological speciation in fish can lead to divergent MeHg accumulation pattern

Analysis of 3,4-Methylenedioxymethamphetamine (MDMA) and its Metabolites in Plasma and Urine by HPLC-DAD and GC-MS

In Europe, the compound 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy, Adam), in addition to cannabis, is the most abused illicit drug at all-night "techno” parties. Methods for the determination of MDMA and its metabolites, 4-hydroxy-3-methoxymethamphetamine (HMMA), 3,4-dihydroxymethamphetamine (HHMA), 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxyamphetamine (HMA), and 3,4-dihydroxyamphetamine (HHA), in biological fluids were established. Plasma and urine samples were collected from two patients in a controlled clinical study over periods of 9 and 22 h, respectively. MDMA and MDA were determined in plasma and urine by reversed-phase high-performance liquid chromatography with diode array detection (HPLC-DAD) after solid-phase extraction on cation-exchange columns. Acidic or enzymatic hydrolysis was necessary to detect HMMA, HMA, HHMA, and HHA, which are mainly excreted as glucuronides. Gas chromatography-mass spectrometry (GC-MS) was used for confirmation. Sample extraction and on-disc derivatization with heptafluorobutyric anhydride (HFBA) were performed on Toxi-Lab SPEC solid-phase extraction concentrators. After administration of a single oral dose of 1.5 mg/kg body weight MDMA, peak plasma levels of 331 ng/mL MDMA and 15 ng/mL MDA were measured after 2 h and 6.3 h, respectively. Peak concentrations of 28.1 µg/mL MDMA in urine appeared after 21.5 h. Up to 2.3 µg/mL MDA, 35.1 µg/mL HMMA, and 2.1 µg/mL HMA were measured within 16-21.5 h. Conjugated HMMA and HHMA are the main urinary metabolites of MDM

A Stable Polyaniline-Benzoquinone-Hydroquinone Supercapacitor

A Polyaniline‐Supercapacitor with quinone electrolytes remains stable over 50 000 galvanostatic charge‐discharge cycles. The quinones provide superior stability by preventing the conversion of porous polyaniline to a highly reactive state. Our work shows that highly stable polymer‐supercapacitors can be engineered by combining electrochemically active polymers and redox‐active electrolytes with concerted electrochemical properties

A Stable Polyaniline-Benzoquinone-Hydroquinone Supercapacitor

A Polyaniline‐Supercapacitor with quinone electrolytes remains stable over 50 000 galvanostatic charge‐discharge cycles. The quinones provide superior stability by preventing the conversion of porous polyaniline to a highly reactive state. Our work shows that highly stable polymer‐supercapacitors can be engineered by combining electrochemically active polymers and redox‐active electrolytes with concerted electrochemical properties

Design of aqueous redox-enhanced electrochemical capacitors with high specific energies and slow self-discharge

Electrochemical double-layer capacitors exhibit high power and long cycle life but have low specific energy compared with batteries, limiting applications. Redox-enhanced capacitors increase specific energy by using redox-active electrolytes that are oxidized at the positive electrode and reduced at the negative electrode during charging. Here we report characteristics of several redox electrolytes to illustrate operational/self-discharge mechanisms and the design rules for high performance. We discover a methyl viologen (MV)/bromide electrolyte that delivers a high specific energy of ~14 Wh kg⁻¹ based on the mass of electrodes and electrolyte, without the use of an ion-selective membrane separator. Substituting heptyl viologen for MV increases stability, with no degradation over 20,000 cycles. Self-discharge is low, due to adsorption of the redox couples in the charged state to the activated carbon, and comparable to cells with inert electrolyte. An electrochemical model reproduces experiments and predicts that 30–50 Wh kg⁻¹ is possible with optimization.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Nature Publishing Group. The published article can be found at: http://www.nature.com/ncomms/2015/150804/ncomms8818/full/ncomms8818.htm

EVAluation of Soybean varieties for low Input and Organic productioN under stressed conditions (EVASION) 2021–2024

Weed competitiveness of soybean varieties is a desirable trait for organic, but also for non-organic production, as the use of herbicides is increasingly limited. Soybean cultivation will have to cope more often with drought in the future. The objective of the EVASION project (2021-2024) is to improve the assessment of varieties in order to identify the ones with the best behavior in stress conditions, following the effort of breeding companies to offer new lines with new characteristics. Variety evaluation usually consists in comparing candidate varieties performances to « standard » varieties, in multilocal trials. This is usually not enough to identify the varieties with the best potential in limiting conditions, like drought or strong weed infestation, as stress conditions may result in the abandon of the location, due to an extreme high variability among plots and locations. It is therefore important to define a new methodology to assess variety performance in a large range of growing conditions. The first step will consist in improving the knowledge of variety adaptation to drought and weed stress and their interactions. The best strategies (morphological and physiological) will be identified in field trials. The second step will be to test non destructive measurement tools and choose the most relevant for routine evaluation. The third step will be to implement these methods to routine evaluation, in organic and non-organic trials. At the end of the project we will have new evaluation strategies allowing to propose varieties with better performance in stress conditions, for both feed and food, and better description of each variety potential depending on the environmental conditions. Furthermore, farmers will learn about soybean cultivation and implications of drought, stress- and weed tolerant varieties thanks to strip trials and field visits and by other dissemination activities

Biphenyl-cyclophanes : the molecular control over the conductivity of single-molecule junctions

The ongoing miniaturization trend in the semiconductor industry will soon reach its technical and physical limit. Alternative concepts are required which allow a further reduction in size of the electronic active components. The idea to build cheap semiconductor devices with molecular-scale components is fueling the current interest in Molecular Electronics. However, our ultimate goal is to understand and master single-molecule devices. Organic molecules are very attractive because they can be engineered with high complexity, and their intrinsic physical properties can be tuned by chemists. Electronic devices such as switches or rectifiers using molecular systems have already been demonstrated. Scientists have yet to develop a profound understanding of charge transport through a single molecular wire. The ultimate goal of this thesis is to develop, design and synthesize model compounds in order to contribute to the comprehension of structure-transport relationships in single molecule junctions. The idea was to design and synthesize new “test sets” of model compounds and to characterize their electrical, electronic, optical and electrochemical properties in a multidisciplinary cooperation with physicists. In contrast to ensemble experiments, the observation of a single molecule uncovers molecular characteristics which would otherwise be averaged out in the bulk. To corroborate the molecular nature of observed transport characteristics a series of molecules with a single well defined variation of their torsion angle was investigated. In order to gain access to parallel series of model compounds as “test sets”, a synthetic strategy was developed allowing post-modification of the principal model structures with various chemical labels, namely anchoring groups. Biphenyl-cyclophanes, functionalized with acetyl-protected thiol groups in their terminal positions, as a series of molecules of similar length and substitution pattern and the π-backbone conformation as the only structural variable, were first proposed and synthesized. Charge transport investigations using a STM-based break junction technique revealed that electronic hole transport through the HOMO linearly depends on the cos2Φ of the torsion angle. In order to explore the extent to which these findings also apply to electrons delocalized in the structure’s LUMO a series of dicyano-biphenyl-cyclophanes were synthesized and studied. Transport investigation showed that the electron transport through the LUMO also follows the cos2Φ relation. Furthermore, a two step electrochemical reduction process was observed. Thereby, the potential gap between both reduction processes was found to follow the cos2Φ relation. Optical absorption spectroscopy of both series showed that the vertical excitation energy of the conjugation band correlates with the cos2Φ of the torsion angle. These correlations demonstrate that the angle measured in the solid state structure is a good proxy for the molecular conformation in solution. Furthermore, spectroelectrochemical investigations and DFT calculations support these observations. X-ray structures of nearly all model compounds, provided the torsion angles used in these correlations. The conductance values of the fully planar model structures did not follow the trend. To understand this unexpected behavior of the fluorene derivates within the respective series several fully planer biphenyl structures were synthesized. While the axial length within the series remains similar, the type of chemical bridge in 2,2’-position of the biphenyl scaffold varies. Interesting candidates for charge transport investigation were the dibenzo-norcaradiene derivates which represent an unbent biphenyl system. Furthermore, thiol and cyano groups were installed in the terminal position to investigate hole and electron transport. Optical absorption measurements showed that the π-systems are highly sensitive to the chemical nature of the second bridge in these planar biphenyl structures. To conclude, this thesis discusses the relationship between molecular structure and electronic and electrical properties of several series of biphenyl systems with an emphasis on the spatial molecular conformation and the single-molecule conductance in solution. Due to the large number of related structures within a series the measured transport signatures could be assigned to their molecular origin

Hydroxycyclopentanone derivatives from D-Mannose via ring closing metathesis: An improved synthesis of a key intermediate of Tricyclo-DNA

A large scale, 10 step synthesis of cyclopentanone 1 , starting from the chiral pool compound D-mannose, is described. The synthesis proceeds via a ring closing metathesis reaction as the key step in an overall yield of 23%. Cyclopentanone 1 is a central intermediate for the synthesis of tricyclo-DN

Analysis of 3,4-Methylenedioxymethamphetamine (MDMA) and its Metabolites in Plasma and Urine by HPLC-DAD and GC-MS

In Europe, the compound 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy, Adam), in addition to cannabis, is the most abused illicit drug at all-night “techno” parties. Methods for the determination of MDMA and its metabolites, 4-hydroxy-3-methoxymethamphetamine (HMMA), 3,4-dihydroxymethamphetamine (HHMA), 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxyamphetamine (HMA), and 3,4-dihydroxyamphetamine (HHA), in biological fluids were established. Plasma and urine samples were collected from two patients in a controlled clinical study over periods of 9 and 22 h, respectively. MDMA and MDA were determined in plasma and urine by reversed-phase high-performance liquid chromatography with diode array detection (HPLC-DAD) after solid-phase extraction on cation-exchange columns. Acidic or enzymatic hydrolysis was necessary to detect HMMA, HMA, HHMA, and HHA, which are mainly excreted as glucuronides. Gas chromatography-mass spectrometry (GC-MS) was used for confirmation. Sample extraction and on-disc derivatization with heptafluorobutyric anhydride (HFBA) were performed on Toxi-Lab SPEC solid-phase extraction concentrators. After administration of a single oral dose of 1.5 mg/kg body weight MDMA, peak plasma levels of 331 ng/mL MDMA and 15 ng/mL MDA were measured after 2 h and 6.3 h, respectively. Peak concentrations of 28.1 µg/mL MDMA in urine appeared after 21.5 h. Up to 2.3 µg/mL MDA, 35.1 µg/mL HMMA, and 2.1 µg/mL HMA were measured within 16–21.5 h. Conjugated HMMA and HHMA are the main urinary metabolites of MDMA