86 research outputs found
3D Nanofabrication inside rapid prototyped microfluidic channels showcased by wet-spinning of single micrometre fibres
Microfluidics is an established multidisciplinary research domain with
widespread applications in the fields of medicine, biotechnology and
engineering. Conventional production methods of microfluidic chips have been
limited to planar structures, preventing the exploitation of truly
three-dimensional architectures for applications such as multi-phase droplet
preparation or wet-phase fibre spinning. Here the challenge of nanofabrication
inside a microfluidic chip is tackled for the showcase of a spider-inspired
spinneret. Multiphoton lithography, an additive manufacturing method, was used
to produce free-form microfluidic masters, subsequently replicated by soft
lithography. Into the resulting microfluidic device, a threedimensional
spider-inspired spinneret was directly fabricated in-chip via multiphoton
lithography. Applying this unprecedented fabrication strategy, the to date
smallest printed spinneret nozzle is produced. This spinneret resides tightly
sealed, connecting it to the macroscopic world. Its functionality is
demonstrated by wet-spinning of single-digit micron fibres through a
polyacrylonitrile coagulation process induced by a water sheath layer. The
methodology developed here demonstrates fabrication strategies to interface
complex architectures into classical microfluidic platforms. Using multiphoton
lithography for in-chip fabrication adopts a high spatial resolution technology
for improving geometry and thus flow control inside microfluidic chips. The
showcased fabrication methodology is generic and will be applicable to multiple
challenges in fluid control and beyond
Combining Deep Eutectic Solvents with TEMPO‐based Polymer Electrodes: Influence of Molar Ratio on Electrode Performance
For sustainable energy storage, all-organic batteries based on redox-active polymers promise to become an alternative to lithium ion batteries. Yet, polymers contribute to the goal of an all-organic cell as electrodes or as solid electrolytes. Here, we replace the electrolyte with a deep eutectic solvent (DES) composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) and N-methylacetamide (NMA), while using poly(2,2,6,6-tetramethylpiperidin-1-yl-oxyl methacrylate) (PTMA) as cathode. The successful combination of a DES with a polymer electrode is reported here for the first time. The electrochemical stability of PTMA electrodes in the DES at the eutectic molar ratio of 1 : 6 is comparable to conventional battery electrolytes. More viscous electrolytes with higher salt concentration can hinder cycling at high rates. Lower salt concentration leads to decreasing capacities and faster decomposition. The eutectic mixture of 1 : 6 is best suited uniting high stability and moderate viscosity
Influence of Chloride and Nitrate Anions on Copper Electrodeposition onto Au(111) from Deep Eutectic Solvents
Copper electrodeposition on Au(111) from deep eutectic solvents (DESs) type III was investigated employing cyclic voltammetry as well as chronoamperometry. It was further examined on Au(poly) using the electrochemical quartz crystal microbalance (EQCM). The employed DESs are mixtures of choline chloride (ChCl) or choline nitrate (ChNO) with ethylene glycol (EG) as hydrogen bond donor (HBD), each in a molar ratio of 1 : 2. CuCl, CuCl, or Cu(NO) ⋅ 3HO were added as copper sources. Underpotential deposition (UPD) of Cu precedes bulk deposition in chloride as well as nitrate electrolytes. Cu deposition from Cu in chloride media is observed as a one-electron reaction, whereas deposition from Cu occurs in two steps since Cu is strongly stabilized by chloride. Cu is less stabilized by nitrate and the beginning of bulk deposition in the nitrate-containing DES with Cu is shifted by several hundred mV to more positive potentials compared to the chloride DES. A diffusion-controlled, three-dimensional nucleation and growth mechanism is found by chronoamperometric measurements and analysis based on the model of Scharifker and Mostany
Conjugated Polyimidazole Nanoparticles as Biodegradable Electrode Materials for Organic Batteries
Conjugated polymers are promising active materials for batteries. Batteries not only need to have high energy density but should also combine safe handling with recyclability or biodegradability after reaching their end-of-life. Here, π-conjugated polyimidazole particles are developed, which are prepared using atom economic direct arylation adapted to a dispersion polymerization protocol. The synthesis yields polyimidazole nanoparticles of tunable size and narrow dispersity. In addition, the degree of crosslinking of the polymer particles can be controlled. It is demonstrated that the polyimidazole nanoparticles can be processed together with carbon black and biodegradable carboxymethyl cellulose binder as an active material for organic battery electrodes. Electrochemical characterization shows that a higher degree of crosslinking significantly improves the electrochemical performance and leads to clearer oxidation and reduction signals of the polymer. Polyimidazole as part of the composite electrode shows complete degradation by exposure to composting bacteria over the course of 72 h
All‐Organic Battery Based on Deep Eutectic Solvent and Redox‐Active Polymers
Sustainable battery concepts are of great importance for the energy storage demands of the future. Organic batteries based on redox-active polymers are one class of promising storage systems to meet these demands, in particular when combined with environmentally friendly and safe electrolytes. Deep Eutectic Solvents (DESs) represent a class of electrolytes that can be produced from sustainable sources and exhibit in most cases no or only a small environmental impact. Because of their non-flammability, DESs are safe, while providing an electrochemical stability window almost comparable to established battery electrolytes and much broader than typical aqueous electrolytes. Here, we report the first all-organic battery cell based on a DES electrolyte, which in this case is composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) and N-methylacetamide (NMA) alongside the electrode active materials poly(2,2,6,6-tetramethylpiperidin-1-yl-oxyl methacrylate) (PTMA) and crosslinked poly(vinylbenzylviologen) (X-PVBV). The resulting cell shows two voltage plateaus at 1.07 V and 1.58 V and achieves Coulombic efficiencies of 98 %. Surprisingly, the X-PVBV/X-PVBV redox couple turned out to be much more stable in NaTFSI : NMA 1 : 6 than the X-PVBV/X-PVBV couple, leading to asymmetric capacity fading during cycling tests
Hydrogen bonding in water under extreme confinement unveiled by nanoscale vibrational spectroscopy and simulations
Fluids under extreme confinement exhibit distinctly new properties compared
to their bulk analogs. Understanding the structure and intermolecular bonding
of confined water lays the foundation for creating and improving applications
at the water-energy nexus. However, probing confined water experimentally at
the length scale of intermolecular and surface forces has remained a challenge.
Here, we report a combined experiment/theory framework to reveal changes in
H-bonding environment and the underlying molecular structure of confined water
inside individual carbon nanotubes. H-bonding is directly probed through the
O-H stretch frequency with vibrational electron energy-loss spectroscopy and
compared to spectra from molecular-dynamics simulations based on
density-functional-theory. Experimental spectra show that water in larger
carbon nanotubes exhibit the bonded O-H vibrations of bulk water, but at
smaller diameters, the frequency blueshifts to near the 'free' O-H stretch
found in water vapor and hydrophobic surfaces. The matching simulations reveal
that, in addition to steric confinement, the tube's vibrations play a key role
in breaking up the H-bond network, resulting in an orientationally-dispersed,
non-H-bonded phase. Furthermore, the temperature-dependence of the vibrations
is investigated, providing insights into phase transitions and the
confined-water density. This research demonstrates the potential of the
experiment/theory framework to explore unprecedented aspects of structure and
bonding in confined fluids
Disease- and sex-specific differences in patients with heart valve disease: a proteome study
Pressure overload in patients with aortic valve stenosis and volume overload in mitral valve regurgitation trigger specific forms of cardiac remodeling; however, little is known about similarities and differences in myocardial proteome regulation. We performed proteome profiling of 75 human left ventricular myocardial biopsies (aortic stenosis = 41, mitral regurgitation = 17, and controls = 17) using high-resolution tandem mass spectrometry next to clinical and hemodynamic parameter acquisition. In patients of both disease groups, proteins related to ECM and cytoskeleton were more abundant, whereas those related to energy metabolism and proteostasis were less abundant compared with controls. In addition, disease group-specific and sex-specific differences have been observed. Male patients with aortic stenosis showed more proteins related to fibrosis and less to energy metabolism, whereas female patients showed strong reduction in proteostasis-related proteins. Clinical imaging was in line with proteomic findings, showing elevation of fibrosis in both patient groups and sex differences. Disease- and sex-specific proteomic profiles provide insight into cardiac remodeling in patients with heart valve disease and might help improve the understanding of molecular mechanisms and the development of individualized treatment strategies
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