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Teaching Acid-Base Equilibria by Using Log-log Diagrams: Chemical Education
No full textThe purpose of this column consists in illustrating the utility of log-log diagrams for the graphical determination of the pH value of acid-base systems in dilute aqueous solution. This methodology allows to tackle systems going well beyond the case of mono- or diprotic acids, providing fast and accurate estimations of the pH. It is also argued that the use of so-called Sillén diagrams affords a better understanding of complex acid-base systems
Attosecond Photoionization Dynamics: from Molecules over Clusters to the Liquid Phase
Get PDFPhotoionization is a process taking place on attosecond time scales. How its properties evolve from isolated particles to the condensed phase is an open question of both fundamental and practical relevance. Here, we review recent work that has advanced the study of photoionization dynamics from atoms to molecules, clusters and the liquid phase. The first measurements of molecular photoionization delays have revealed the attosecond dynamics of electron emission from a molecular shape resonance and their sensitivity to the molecular potential. Using electron-ion coincidence spectroscopy these measurements have been extended from isolated molecules to clusters. A continuous increase of the delays with the water-cluster size has been observed up to a size of 4-5 molecules, followed by a saturation towards larger clusters. Comparison with calculations has revealed a correlation of the time delay with the spatial extension of the created electron hole. Using cylindrical liquid-microjet techniques, these measurements have also been extended to liquid water, revealing a delay relative to isolated water molecules that was very similar to the largest water clusters studied. Detailed modeling based on Monte-Carlo simulations confirmed that these delays are dominated by the contributions of the first two solvation shells, which agrees with the results of the cluster measurements. These combined results open the perspective of experimentally characterizing the delocalization of electronic wave functions in complex systems and studying their evolution on attosecond time scales
Near-Quantitative, Catalyst-Free Depolymerization of RAFT Polymethacrylates: Polymer and Colloid Highlights
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Conference Report on the Nobel Symposium #168 “Visions of bio-inorganic chemistry: Metals and the molecules of life” held in Lejondal Castle, Sweden, from May 29 – June 1 2022: Conference Report
No full textThere is usually only one Nobel Symposium per discipline and year, but COVID has also had an effect on this rule. Initially planned to take place in 2020, this Nobel Symposium lined up a unique group of speakers and just about the same number of observers, as well as three members of the scientific press, all by invitation
Hybrid Microfluidic Device for High Throughput Isolation of Cells Using Aptamer Functionalized Diatom Frustules
Get PDFCirculating tumor cells (CTCs), secreted from primary and metastatic malignancies, hold a wealth of essential diagnostic and prognostic data for multiple cancers. Significantly, the information contained within these cells may hold the key to understanding cancer metastasis, both individually and fundamentally. Accordingly, developing ways to identify, isolate and interrogate CTCs plays an essential role in modern cancer research. Unfortunately, CTCs are typically present in the blood in vanishingly low titers and mixed with other blood components, making their isolation and analysis extremely challenging. Herein, we report the design, fabrication and optimization of a microfluidic device capable of automatically isolating CTCs from whole blood. This is achieved in two steps, via the passive viscoelastic separation of CTCs and white blood cells (WBCs) from red blood cells (RBCs), and subsequent active magnetophoretic separation of CTCs from WBCs. We detail the specific geometries required to balance the elastic and inertial forces required for successful passive separation of RBCs, and the use of computational fluid dynamics (CFD) to optimize active magnetophoretic separation. We subsequently describe the use of magnetic biosilica frustules, extracted from Chaetoceros sp. diatoms, to fluorescently tag CTCs and facilitate magnetic isolation. Finally, we use our microfluidic platform to separate HepG2-derived CTCs from whole blood, demonstrating exceptional CTC recovery (94.6%) and purity (89.7%
