How coherent structures dominate the residence time in a bubble wake: an experimental example

Mixing timescales and residence times in reactive multiphase flows can be essential for product selectivity. For instance when a gas species is consumed e.g. by a competitive consecutive reaction with moderate reaction kinetics where reaction timescales are comparable to relevant mixing timescales. To point out the importance of the details of the fluid flow, we analyze experimental velocity data from a Taylor bubble wake by means of Lagrangian methods. By adjusting the channel diameter in which the Taylor bubble rises, and thus the rise velocity, we obtain three different wake regimes. Remarkably the normalized residence times of passive particles advected in the wake velocity field show a peak for intermediate rise velocities. This fact seems unintuitive at first glance because one expects a faster removal of passive tracers for a faster overall flow rate. However, the details of the flow topology analyzed using Finite Time Lyapunov Exponent (FTLE) fields and Lagrangian Coherent Structures (LCS) reveal the existence of a very coherent vortical pattern in the bubble wake which explains the long residence times. The increased residence times within the vortical structure and the close bubble interface acting as a constant gas species source could enhance side product generation of a hypothetical competitive consecutive reaction, where the first reaction with the gas species forms the desired product and the second the side product.Comment: 13 pages, 7 figures, 1 tabl

New Guanidine-Pyridine Copper Complexes and Their Application in ATRP

The guanidine hybrid ligands, (tetramethylguanidine)methylenepyridine (TMGpy) and (dimethylethyleneguanidine)methylenepyridine (DMEGpy), were proven to be able to stabilize copper complexes active in the solvent-free polymerization of styrene at 110 degrees C using 1-phenylethylbromide as the initiator. The polymerization proceeded after first-order kinetics, and polystyrenes with polydispersities around 1.2 could be obtained. Using the ligand, DMEGpy, three new copper guanidine-pyridine complexes could be synthesized and structurally characterized. Their structural characteristics are discussed

Road to a Chemistry-Specific Data Management Plan

In order to develop a discipline-specific data management plan (DMP) template, it is important to obtain information from researchers. For a chemistry-specific template, NFDI4Chem conducted a series of interviews with 27 participants and used data from the RDA WG Discipline-specific Guidance for DMP online survey. The interviews showed that the implementation of research data management in everyday work is a big challenge. Key findings from the interview series highlight challenges in implementing FAIR principles, with a focus on “Findability” and “Reusability.” The importance of linking physical samples and data in chemistry is emphasised, with discussions on storage, archiving, and the use of tools like electronic lab notebooks and repositories. However, documentation methods, software tools, and naming conventions commonly used in chemical research are also addressed. Overall, the study underscores the need for improved resources and strategies to enhance data management practices in the field of chemistry. All the gathered information and examples will be used to develop a DMP template in line with chemistry-specific requirements. The results provide a comprehensive outlook on the future developments of research data management (RDM) in chemistry

New Guanidine-Pyridine Copper Complexes and Their Application in ATRP

The guanidine hybrid ligands, (tetramethylguanidine)methylenepyridine (TMGpy) and (dimethylethyleneguanidine)methylenepyridine (DMEGpy), were proven to be able to stabilize copper complexes active in the solvent-free polymerization of styrene at 110 degrees C using 1-phenylethylbromide as the initiator. The polymerization proceeded after first-order kinetics, and polystyrenes with polydispersities around 1.2 could be obtained. Using the ligand, DMEGpy, three new copper guanidine-pyridine complexes could be synthesized and structurally characterized. Their structural characteristics are discussed

Digitalizing the Chemical Landscape: A Comprehensive Overview and Progress Report of NFDI4Chem

The Chemistry consortium NFDI4Chem aims to digitalise key steps in chemical research, supporting scientists in managing research data throughout its life cycle. The SmartLab, embedded in a federation of services, integrates various tools such as electronic lab notebooks, data repositories, and search services, to create a smart lab environment for structured data gathering. Utilizing terminology services and adhering to data format standards, NFDI4Chem promotes secure and FAIR data sharing, fostering collaboration and expediting scientific discoveries. This development is supported by community building measures, workshops, and training initiatives, along with collaboration on international minimum information standards

NFDI4Chem - A Research Data Network for International Chemistry

Research data provide evidence for the validation of scientific hypotheses in most areas of science. Open access to them is the basis for true peer review of scientific results and publications. Hence, research data are at the heart of the scientific method as a whole. The value of openly sharing research data has by now been recognized by scientists, funders and politicians. Today, new research results are increasingly obtained by drawing on existing data. Many organisations such as the Research Data Alliance (RDA), the goFAIR initiative, and not least IUPAC are supporting and promoting the collection and curation of research data. One of the remaining challenges is to find matching data sets, to understand them and to reuse them for your own purpose. As a consequence, we urgently need better research data management

Towards New Robust Zn(II) Complexes for the Ring-Opening Polymerization of Lactide Under Industrially Relevant Conditions

The synthesis of bio-based and biodegradable plastics is a hot topic in research due to growing environmental problems caused by omnipresent plastics. As a result, polylactide, which has been known for years, has seen a tremendous increase in industrial production. Nevertheless, the manufacturing process using the toxic catalyst Sn(Oct)2 is very critical. As an alternative, five zinc acetate complexes have been synthesized with Schiff base-like ligands that exhibit high activity in the ring-opening polymerization of non-purified lactide. The systems bear different side arms in the ligand scaffold. The influence of these substituents has been analyzed. For a detailed description of the catalytic activities, the rate constants kapp and kp were determined using in-situ Raman spectroscopy at a temperature of 150 °C. The polymers produced have molar masses of up to 71 000 g mol−1 and are therefore suitable for a variety of applications. Toxicity measurements carried out for these complexes proved the nontoxicity of the systems. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

Optically Induced Avoided Crossing in Graphene

Degenerate states in condensed matter are frequently the cause of unwanted fluctuations, which prevent the formation of ordered phases and reduce their functionalities. Removing these degeneracies has been a common theme in materials design, pursued for example by strain engineering at interfaces. Here, we explore a non-equilibrium approach to lift degeneracies in solids. We show that coherent driving of the crystal lattice in bi- and multilayer graphene, boosts the coupling between two doubly-degenerate modes of E1u and E2g symmetry, which are virtually uncoupled at equilibrium. New vibronic states result from anharmonic driving of the E1u mode to large amplitdues, boosting its coupling to the E2g mode. The vibrational structure of the driven state is probed with time-resolved Raman scattering, which reveals laser-field dependent mode splitting and enhanced lifetimes. We expect this phenomenon to be generally observable in many materials systems, affecting the non-equilibrium emergent phases in matter.Comment: 13 pages, 4 figure