Assessing the Effect of Stabilization and Carbonization Temperatures on Electrochemical Performance of Electrospun Carbon Nanofibers from Polyacrylonitrile

Supercapacitors (SCs) are considered a promising alternative to batteries to power up portable and wearable devices. Among different categories of materials for SCs, carbon nanofibers (CNFs) are particularly appealing for their electrochemical, morphological, and mechanical properties, coupled with the ease of synthesis. Electrospinning is a simple and low-cost technique to prepare the polymer-based precursors for CNFs, allowing to obtain fibers with a tunable morphology and a diameter in the nanometer range. However, even if electrospun CNFs were intensely studied over the years, in the literature there is a lack of information regarding the optimization of the thermal treatment to prepare bare CNFs with high specific capacitance (C s). Herein, a systematic study on the optimization of the stabilization and carbonization temperatures for electrospun CNFs prepared from polyacrylonirtile is reported, achieving a maximum C s of 49 F g−1 at 0.5 A g−1 in a symmetrical SC device based on 1 m H2SO4 electrolyte. Aspects related to the specific surface area, nitrogen doping, and carbon microstructure are examined concerning the different thermal treatments, allowing to define structure–property–function relationships in these capacitive nanoarchitectures

Soft X-ray spectroscopy as a probe for gas-phase protein structure:Electron impact ionization from within

Preservation of protein conformation upon transfer into the gas‐phase is key for structure determination of free single molecules, e.g. using X‐ray free‐electron lasers. In the gas phase, the helicity of melittin decreases strongly as the protein's protonation state increases. We demonstrate the sensitivity of soft X‐ray spectroscopy to the gas phase conformation of melittin cations ([melittin+qH]q+, q=2‐4) in a cryogenic linear radiofrequency ion trap. With increasing helicity we observe a decrease of the dominating carbon 1s‐* transition in the amide C=O bonds for non‐dissociative single ionization and an increase for non‐dissociative double ionization. As the underlying mechanism we identify inelastic electron scattering. Using an independent atom model we show that the more compact nature of the helical protein conformation substantially increases the probability for off‐site intramolecular ionization by inelastic Auger electron scattering

Hibiscus sabdariffa L. - A phytochemical and pharmacological review

Hibiscus sabdariffa L. (Hs, roselle; Malvaceae) has been used traditionally as a food, in herbal drinks, in hot and cold beverages, as a flavouring agent in the food industry and as a herbal medicine. In vitro and in vivo studies as well as some clinical trials provide some evidence mostly for phytochemically poorly characterised Hs extracts. Extracts showed antibacterial, anti-oxidant, nephro- and hepato-protective, renal/diuretic effect, effects on lipid metabolism (anti-cholesterol), anti-diabetic and anti-hypertensive effects among others. This might be linked to strong antioxidant activities, inhibition of α-glucosidase and α-amylase, inhibition of angiotensin-converting enzymes (ACE), and direct vaso-relaxant effect or calcium channel modulation. Phenolic acids (esp. protocatechuic acid), organic acid (hydroxycitric acid and hibiscus acid) and anthocyanins (delphinidin-3-sambubioside and cyanidin-3-sambubioside) are likely to contribute to the reported effects. More well designed controlled clinical trials are needed which use phytochemically characterised preparations. Hs has an excellent safety and tolerability record. © 2014 The Authors. Published by Elsevier Ltd

Referent: Dr. Bernd Boll (Freiburg)

Dokument oder Propaganda? Quellenkritische Anmerkungen zum Foto- und Filmmaterial der deutschen Propagandatruppen 1938-1945 (Vortrag) Trotz großer Verluste in den letzten Kriegswochen sind fast eine Million Einzelaufnahmen und 300.000 Meter Wochenschau-Film der deutschen Propagandakompanien (PK) aus dem Zweiten Weltkrieg im Bundesarchiv überliefert. Dieses Bildmaterial prägte die Vorstellung des Publikums vom Zweiten Weltkrieg entscheidend mit. Aber geben diese Bilder als dessen visuelle Sig..

Referent: Dr. Bernd Boll (Freiburg)

Dokument oder Propaganda? Quellenkritische Anmerkungen zum Foto- und Filmmaterial der deutschen Propagandatruppen 1938-1945 (Vortrag) Trotz großer Verluste in den letzten Kriegswochen sind fast eine Million Einzelaufnahmen und 300.000 Meter Wochenschau-Film der deutschen Propagandakompanien (PK) aus dem Zweiten Weltkrieg im Bundesarchiv überliefert. Dieses Bildmaterial prägte die Vorstellung des Publikums vom Zweiten Weltkrieg entscheidend mit. Aber geben diese Bilder als dessen visuelle Sig..

Feeding a grape seed extract extends the survival of the red flour beetle Tribolium castaneum under heat-stress depending on nrf-2, jnk-1, and foxo-1 homologous genes but independent of catechin monomers

Besides caloric restriction, a diet rich in fruits and vegetables is believed to delay the ageing process thus providing a powerfull tool in preventive medicine. To investigate underlying interactions between food ingredients and genes simple models, such as the red flour beetle Tribolium castaneum, appear especially constructive. Here we show that 1 % of a grape seed extract containing 30 % of procyanidins, significantly increases the survival of T. castaneum at 42 °C when added to flour as a dietary source. The beneficial effects of grape seed extract could not be reproduced by supplementing flour with single catechins of which the oligomeric procyanidins consist. We identified previously stress resistance genes responsible for a survival extension by dietary ingredients and show here by the use of RNA-interference that a knockdown of transcripts encoding homologues of Nrf-2 or Jnk-1 block the effects of grape seed extract on survival. Interestingly, grape seed extract under knockdown of Foxo-1 caused a significant survival reduction, stressing the hormetic response as underlying the survival extension by the dietary interventions. In conclusion, our studies provide evidence that a procyanidin-rich extract is able to extend the survival of the model organism T. castaneum. Catechin monomers, however, appear not to mediate the effects. The active ingredients, moreover, need the presence of stress resistance factors, and here especially of Foxo-1, in order to promote their preventive activities with regard to degenerations

Social security and intergenerational redistribution: a generational accounting perspective

SIGLEAvailable from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel W 348 (41) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman