Publications by authors named "Ralf Meyer"
Methods that accelerate the evaluation of molecular properties are essential for chemical discovery. While some degree of ligand additivity has been established for transition metal complexes, it is underutilized in asymmetric complexes, such as the square pyramidal coordination geometries highly relevant to catalysis. To develop predictive methods beyond simple additivity, we apply a many-body expansion to octahedral and square pyramidal complexes and introduce a correction based on adjacent ligands (i.
View Article and Find Full Text PDFExpert opinion on design and endpoints for studies on catheter ablation of atrial fibrillation.
J Cardiovasc Electrophysiol
November 2024
Article Synopsis
- Catheter ablation for atrial fibrillation (AF) is widely researched, and this expert opinion aims to enhance future studies by applying lessons from past research and promoting consistency in methodologies.
- The effectiveness of these studies can improve with clearly defined endpoints and a thorough understanding of emerging technologies, as well as a need to revisit some current research methods.
- A panel of clinical experts has produced recommendations highlighting essential elements such as documenting clinical details, managing medications during trials, and assessing outcomes to aid in the standardization and quality of AF catheter ablation studies.
Article Synopsis
- Approximate density functional theory (DFT) is crucial for balancing cost and accuracy in large-scale screenings, but no universally accurate density functional approximation (DFA) has been identified yet.
- The authors developed a DFA recommender that uses electron density fitting and Δ-learning to identify the DFA with the least expected error relative to more accurate but expensive methods like coupled cluster theory.
- Their approach shows excellent performance in predicting spin splitting energies in transition metal complexes and could help bridge the accuracy vs. scope gap in computational chemistry.
Over the last years, inverse gas chromatography (IGC) proved to be a versatile and sensitive analytical technique for physicochemical properties. However, the comparability of results obtained by different users and devices remains a topic for debate. This is the first time, an interlaboratory study using different types of IGC instruments is reported.
View Article and Find Full Text PDFComparison and Incorporation of Reasoning and Learning Approaches for Cancer Therapy Research.
Stud Health Technol Inform
September 2023
Representing knowledge in a comprehensible and maintainable way and transparently providing inferences thereof are important issues, especially in the context of applications related to artificial intelligence in medicine. This becomes even more obvious if the knowledge is dynamically growing and changing and when machine learning techniques are being involved. In this paper, we present an approach for representing knowledge about cancer therapies collected over two decades at St.
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- * Different simulation methods, including molecular dynamics and phonon Monte Carlo simulations, are used to analyze how these kinks influence heat flow and overall thermal behavior.
- * Results show that the impact of kink angles on heat flow is complicated, depending on factors like crystal orientation and transport modeling, with phonon Monte Carlo simulations revealing that heat flow tends to be concentrated in a smaller area than the actual size of the nanowire.
Article Synopsis
- Surface-modified porous silica is studied through inverse gas chromatography (IGC) to understand its interaction with various probe molecules before and after modification with (3-mercaptopropyl)trimethoxysilane.
- The modification reduces the free surface energy and wettability of silica due to decreased polar interactions and silanol groups, leading to a significant loss in Lewis acidity.
- IGC experiments also reveal two distinct types of adsorption complexes based on probe molecule interactions with the silica surface, with differences in their thermal behavior indicated by varying isokinetic temperatures.
Article Synopsis
- To enhance the exploration of chemical compounds, researchers need to focus on finding the most informative and valuable compounds, especially in the area of lower-symmetry mononuclear octahedral transition metal complexes.
- A study of around 1000 Fe(II) complexes reveals a much larger theoretical space (∼816k) for accessible complexes, emphasizing the effectiveness of ligand combinations and the concept of ligand additivity for predicting properties.
- The team proposes a multi-step strategy to identify promising complexes within this larger space, successfully validating their method with nine new complexes that show potential for efficient discovery in targeted property regions.
Despite marked progress in the management of atrial fibrillation (AF), detecting AF remains difficult and AF-related complications cause unacceptable morbidity and mortality even on optimal current therapy. This document summarizes the key outcomes of the 8th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Eighty-three international experts met in Hamburg for 2 days in October 2021.
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- - Graft-versus-host disease (GvHD) is a serious complication post-transplantation, and diagnosing its skin form is tough due to similarities with drug reactions and viral rashes.
- - A study analyzed biopsies from acute GvHD and other skin conditions, finding significant changes in immune cell populations, such as fewer Langerhans cells and more macrophages in GvHD skin.
- - The distinct presence of certain T cells and natural killer cells in GvHD compared to other conditions suggests a unique inflammatory profile that could improve diagnostic accuracy.
Article Synopsis
- - Orbital-free approaches aim to enhance the effectiveness of density functional theory, allowing for larger system sizes in computational chemistry and physics.
- - Snyder et al. developed a machine learning method for the kinetic energy density functional, which worked well in a simple 1D scenario, but struggled with functional derivatives essential for optimization.
- - This research improves upon the original method by incorporating functional derivatives into machine learning training, exploring not only kernel ridge regression but also advanced techniques like convolutional neural networks used in image processing.
Article Synopsis
- The article provides a systematic review of methods for fabricating macroporous α-AlO with high specific surface areas (HSSA), analyzing various published studies and experimental results.
- It discusses major fabrication techniques such as hydrothermal methods, dopants, and sol-gel syntheses, while also revealing the limitations and thermodynamic stability of different alumina modifications.
- The authors highlight their own novel sol-gel synthesis, along with promising results from Mn-assisted transitions and the impact of carbon filling on the formation of α-AlO seeds.
Article Synopsis
- Locating the minimum energy structure of molecules, known as geometry optimization, is a crucial step in computational chemistry.
- Early research focused on developing molecule-specific coordinates for faster convergence to energy minima, while recent methods use machine learning, particularly reverting to Cartesian coordinates for efficiency.
- This study demonstrates that combining Gaussian process regression with advanced coordinate systems in geometry optimization can enhance machine learning performance, validated through benchmarks with 30 small covalently bonded molecules.
The localization of transition states and the calculation of reaction pathways are routine tasks of computational chemists but often very CPU-intense problems, in particular for large systems. The standard algorithm for this purpose is the nudged elastic band method, but it has become obvious that an "intelligent" selection of points to be evaluated on the potential energy surface can improve its convergence significantly. This article summarizes, compares, and extends known strategies that have been heavily inspired by the machine learning developments of recent years.
View Article and Find Full Text PDFSurface modification of porous glass beads by ethanol-based 3-mercaptopropyltrimethoxysilane (MPTMS) grafting solutions is directly evidenced by nitrogen adsorption, elemental analysis, thermogravimetry, infrared and Si CP MAS NMR spectroscopy. Furthermore, the energetic characterization of the surface is essential to understand comprehensively the physico-chemical interactions between the pristine and MPTMS-modified surface and its gas/liquid-phase environment. In this study, inverse gas chromatography (IGC) is used to characterize the surface properties of porous glass (PG).
View Article and Find Full Text PDFThe 0.4 K internal temperature of superfluid helium nanodroplets is believed to guarantee a corresponding ground-state population of dopant atoms and molecules inside this cryogenic matrix. We have recorded 6s ← 5p excitation spectra of indium atoms in helium droplets and found two absorption bands separated by about 2000 cm, a value close to the spin-orbit (SO) splitting of the In P ground state.
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- The use of advanced lasers with shorter pulse lengths allows for the observation of rapid chemical reactions at the level of electron and nucleus movements.
- Superfluid helium serves as a unique solvent enabling the creation of new molecules, but the effect of photoexcitation on its surrounding solvent shell is not fully understood.
- Research involving femtosecond pump-probe spectroscopy reveals that when indium atoms are excited within helium nanodroplets, the solvation shell expands quickly, prompting a collaborative oscillation pattern that influences molecular dynamics.
Article Synopsis
- A recent study introduces a new method for chiral separation using functionalized, nanoporous graphene sheets, which is aimed at improving the separation of chiral molecules.
- The article explores the principles behind this method and suggests various functionalization options for targeting specific chiral drug molecules.
- The authors evaluate different computational chemistry methods, concluding that the GFN-xTB approach is the most effective for simulating functionalized pores, as it aligns closely with results from the more complex density functional theory.
Article Synopsis
- A multicenter study evaluated the safety and pharmacokinetics of intravenous posaconazole for antifungal prophylaxis in neutropenic patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or after allogeneic hematopoietic stem cell transplantation (HSCT).
- A total of 237 patients received a specific dosing regimen of posaconazole, and their drug levels were monitored throughout the treatment.
- Results showed that the drug was well tolerated with low side effects, and there were only a few cases of invasive fungal disease reported, indicating effective prophylaxis in high-risk patients.
Article Synopsis
- - The new European regulation for in vitro diagnostics (IVD) separates the certification of these diagnostics, including companion diagnostics (CDx), from the market authorization process for medicines, requiring notified bodies (NB) to conduct conformity assessments.
- - CDx will now need to provide clinical evidence for certification, marking a shift from the previous practice where manufacturers mainly conducted self-assessments.
- - Close collaboration between the European Medicines Agency (EMA) and NB is essential since the effectiveness of a medicine can rely on the performance of its CDx, making detailed information on CDx from clinical trials vital for evaluating competing diagnostics.
A roadmap to improve the quality of atrial fibrillation management: proceedings from the fifth Atrial Fibrillation Network/European Heart Rhythm Association consensus conference.
Europace
January 2016
Article Synopsis
- Atrial fibrillation (AF) affects at least 30 million people globally and is associated with significant health risks like strokes, heart failure, and high mortality rates, even with existing treatments.
- There is a critical need to improve preventive measures and identify treatable causes of AF, as many cases remain undiagnosed or poorly managed.
- The fifth Atrial Fibrillation Network conference focused on enhancing AF care through collaboration, patient-centered approaches, structured management, quality improvement, and personalized treatment plans, alongside outlining key research priorities for AF.
Fundamental development of a biocompatible and degradable nanocarrier platform based on hydroxyethyl starch (HES) is reported. HES is a derivative of starch and possesses both high biocompatibility and improved stability against enzymatic degradation; it is used to prepare nanocapsules via the polyaddition reaction at the interface of water nanodroplets dispersed in an organic miniemulsion. The synthesized hollow nanocapsules can be loaded with hydrophilic guests in its aqueous core, tuned in size, chemically functionalized in various pathways, and show high shelf life stability.
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- Salvage therapy combined with high-dose therapy (HDT) is crucial for patients with relapsed lymphoma, but there's no best treatment plan established yet.
- The study focused on the R-DexaBEAM regimen, which includes rituximab and several other drugs, for patients aged 18-65 with relapsed/refractory B-cell non-Hodgkin lymphoma (NHL).
- Results showed a 62% response rate for aggressive NHL and a 78% rate for indolent NHL, with significant survival outcomes, suggesting R-DexaBEAM followed by HDT is a promising salvage treatment option.