29 research outputs found
Field-induced compensation of magnetic exchange as the origin of superconductivity above \texorpdfstring{40\,T}{40~T} in \texorpdfstring{\UTe}{UTe2}
The potential spin-triplet heavy-fermion superconductor \UTe exhibits
signatures of multiple distinct superconducting phases. For field aligned along
the axis, a metamagnetic transition occurs at \HmT. It
is associated with magnetic fluctuations that may be beneficial for the
field-enhanced superconductivity surviving up to \Hm. Once the field is tilted
away from the towards the axis, a reentrant superconducting phase
emerges just above \Hm. In order to better understand this remarkably
field-resistant superconducting phase, we conducted magnetic-torque and
magnetotransport measurements in pulsed magnetic fields. We determine the
record-breaking upper critical field of \HcT and its
evolution with angle. Furthermore, the normal-state Hall effect experiences a
drastic suppression indicative of a reduced band polarization above \Hm in the
angular range around caused by a partial compensation between the
applied field and an exchange field. This promotes the Jaccarino-Peter effect
as a possible mechanism for the reentrant superconductivity above \Hm.Comment: Main text: 27 pages, 4 figure, supplement: 10 pages, 5 figure
Aquatic Global Passive Sampling (AQUA-GAPS) Revisited – First Steps towards a Network of Networks for Organic Contaminants in the Aquatic Environment
Organic contaminants, in particular persistent organic pollutants (POPs), adversely affect water quality and aquatic food webs across the globe. As of now, there is no globally consistent information available on concentrations of dissolved POPs in water bodies. The advance of passive sampling techniques has made it possible to establish a global monitoring program for these compounds in the waters of the world, which we call the Aquatic Global Passive Sampling (AQUA-GAPS) network. A recent expert meeting discussed the background, motivations, and strategic approaches of AQUA-GAPS, and its implementation as a network of networks for monitoring organic contaminants (e.g., POPs and others contaminants of concern). Initially, AQUA-GAPS will demonstrate its operating principle via two proof-of-concept studies focused on the detection of legacy and emerging POPs in freshwater and coastal marine sites using both polyethylene and silicone passive samplers. AQUA-GAPS is set-up as a decentralized network, which is open to other participants from around the world to participate in deployments and to initiate new studies. In particular, participants are sought to initiate deployments and studies investigating the presence of legacy and emerging POPs in Africa, Central and South America
Universal ultrafast detector for short optical pulses based on graphene
Graphene has unique optical and electronic properties that make it attractive as an active material for broadband ultrafast detection. We present here a graphene-based detector that shows 40-picosecond electrical rise time over a spectral range that spans nearly three orders of magnitude, from the visible to the far-infrared. The detector employs a large area graphene active region with interdigitated electrodes that are connected to a log-periodic antenna to improve the long-wavelength collection efficiency, and a silicon carbide substrate that is transparent throughout the visible regime. The detector exhibits a noise-equivalent power of approximately 100 µW·Hz–½ and is characterized at wavelengths from 780 nm to 500 µm
The meaning of my feelings depends on who I am: work-related identifications shape emotion effects in organizations
Theory and research on affect in organizations has mostly approached emotions from a valence perspective, suggesting that positive emotions lead to positive outcomes and negative emotions to negative outcomes for organizations. We propose that cognition resulting from emotional experiences at work cannot be assumed based on emotion valence alone. Instead, building on appraisal theory and social identity theory, we propose that individual responses to discrete emotions in organizations are shaped by, and thus depend on, work-related identifications. We elaborate on this proposition specifically with respect to turnover intentions, theorizing how three discrete emotions - anger, guilt, and pride - differentially affect turnover intentions, depending on two work-related identifications - organizational and occupational identification. A longitudinal study involving 135 pilot instructors reporting emotions, work-related identifications, and turnover intentions over the course of one year provides general support for our proposition. Our theory and findings advance emotion and identity theories by explaining how the effects of emotions are dependent on the psychological context in which they are experienced
A Novel Efficient L-Lysine Exporter Identified by Functional Metagenomics
Lack of active export system often limits the industrial bio-based production processes accumulating the intracellular product and hence complexing the purification steps. L-lysine, an essential amino acid, is produced biologically in quantities exceeding two million tons per year; yet, L-lysine production is challenged by efficient export system at high titers during fermentation. To address this issue, new exporter candidates for efficient efflux of L-lysine are needed. Using metagenomic functional selection, we identified 58 genes encoded on 28 unique metagenomic fragments from cow gut microbiome library that improved L-lysine tolerance. These genes include a novel L-lysine transporter, belonging to a previously uncharacterized EamA superfamily, which is further in vivo characterized as L-lysine exporter using Xenopus oocyte expression system as well as Escherichia coli host. This novel exporter improved L-lysine tolerance in E. coli by 40% and enhanced yield, titer, and the specific production of L-lysine in an industrial Corynebacterium glutamicum strain by 7.8%, 9.5%, and 12%, respectively. Our approach allows the sequence-independent discovery of novel exporters and can be deployed to increase titers and productivity of toxicity-limited bioprocesses
Single‐Molecule Doping : Conductance Changed By Transition Metal Centers in Salen Molecules
The creation of molecular components for use as electronic devices has made enormous progress. In order to advance the field further toward realistic electronic concepts, methods for the controlled modification of the conducting properties of the molecules contacted by metallic electrodes need to be further developed. Here a comprehensive study of charge transport in a class of molecules that allows modifications by introducing metal centers into organic structures is presented. Single molecules are electrically contacted and characterized in order to understand the role of the metal centers in the conductance mechanism through the molecular junctions. It is shown that the presence of single metal ions modifies the energy levels and the coupling of the molecules to the electrical contacts, and that these modifications lead to systematic variations in the statistical behavior of transport properties of the molecular junctions. A rigorous statistical analysis of thousands of junctions is performed to reveal this correlation. The understanding of the role of the metal ion in the resulting conductance properties is an essential step toward the development of molecular electronic circuits.publishe
Introducing molasses as an alternative feedstock into itaconate production using Ustilago sp
In this work, we established an efficient process for the production of itaconate from the regionally sourced industrial side-stream molasses using Ustilago cynodontis and Ustilago maydis. While being relatively cheap and more environmentally friendly than refined sugars, there are some major challenges to overcome when working with molasses. Some of those challenges are a high nitrogen load, unknown impurities in the feedstock, and high amounts of ill-favoured carbon sources, such as sucrose or lactate. We could show that the activity of the sucrose-hydrolysing enzyme invertase plays a crucial role in the efficiency of the process and that the fructose utilisation differs between the two strains used in this work. Thus, with a higher invertase activity, the ability to convert fructose into the desired product itaconate, and an overall higher tolerance towards undesired substances in molasses, U. maydis is better equipped for the process on the alternative feedstock molasses than U. cynodontis. The established process with U. maydis reached competitive yields of up to 0.38 g g−1 and a titre of more than 37 g L−1. This shows that an efficient and cost-effective itaconate production process is generally feasible using U. maydis, which has the potential to greatly increase the sustainability of industrial itaconate production