We report on progress towards a neutral atom imaging device that will be used for chemically sensitive surface microscopy and nanofabrication. Our novel technique for improving refractive power and correcting chromatic aberration in atom lenses is based on a fundamental paradigm shift from continuous-beam focusing to a pulsed, three-dimensional approach. Simulations of this system suggest that it will pave the way toward the long-sought goal of true atom imaging on the nanoscale. Using a prototype lens with a supersonic beam of metastable neon, we have imaged complex patterns with lower distortion and higher resolution than has been shown in any previous experiment. Comparison with simulations corroborates the underlying theory and encourages further refinement of the process.
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http://dx.doi.org/10.1063/1.4976986 | DOI Listing |
Chemistry
January 2025
University of Padova: Universita degli Studi di Padova, Dipartimento di Scienze Chimiche, Via Marzolo 1, 35131, Padova, ITALY.
Chalcogenide exchange reactions are an important class of bimolecular nucleophilic substitution reactions (SN2) involving sulfur and selenium species as nucleophile, central atom, and/or leaving group, which are fundamental throughout redox biology and metabolism. While thiol-disulfide exchange reactions have been deeply investigated, those involving selenium are less understood, especially with regards to the polarised selenenyl sulfides RSe-SR' even though the directed reactivity of selenenyl sulfides is biologically crucial for selenoenzymes such as thioredoxin reductase (TrxR) and glutathione peroxidase (GPx). Synthetic methods to create asymmetric selenenyl sulfides with high regiochemical purity only emerged over the last five years; this functional group has already demonstrated powerful applications to cell biology, through probes for molecular imaging (e.
View Article and Find Full Text PDFAnal Chem
January 2025
Institute of Physical Science and Information Technology, Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, Anhui 230601, China.
Real-time monitoring of the dynamics of cytosolic RNA-protein condensates, termed stress granules (SGs), is vital for understanding their biological roles in stress response and related disease treatment but is challenging due to the lack of simple and accurate methods. Compared with protein visualization that requires complex transfection procedures, direct RNA labeling offers an ideal alternative for tracking SG dynamics in living cells. Here, we propose a novel molecular design strategy to construct a near-infrared RNA-specific fluorescent probe () for tracking SGs in living cells.
View Article and Find Full Text PDFLuminescence
January 2025
Department of Mathematical and Natural Sciences, Özyeğin University, Istanbul, Türkiye.
The present study introduces the idea of a novel fluorescence-based imaging technique combined with a microfluidic platform that enables a precise control of dark transient state populations of fluorescent probes flowing over a uniform, top flat supergaussian excitation field with a constant flow rate. To demonstrate the imaging capability of the proposed detection method, numerical simulations have been performed by considering laser, microscope and flow parameters of experimental setup together with photophysical model and electronic transition rates of fluorescent dyes. As an output data to be assessed, fluorescence image data is simulated numerically for bromine-free carboxyfluorescein and its brominated derivatives having different numbers of bromine atoms.
View Article and Find Full Text PDFSmall
January 2025
Key Lab of Bamboo and Rattan Science & Technology, International Center for Bamboo and Rattan, Beijing, 100102, P. R. China.
A nitrogen-coordinated Fe single-atom catalyst (SA Fe-N/C) is synthesized using a homogeneous ethanol-based dissolution system with bamboo kraft lignin serving as the carbon source. Uniformly dispersed Fe atoms with an interatomic distance of less than 2 Å throughout the SA Fe-N/C structure are revealed through X-ray absorption spectral analysis and HAADF-STEM images, which possessed a high Fe loading of 2.69%.
View Article and Find Full Text PDFBiophys J
January 2025
Department of Chemistry, Chicago Center for Theoretical Chemistry, The James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States. Electronic address:
Microtubules (MTs) constitute the largest components of the eukaryotic cytoskeleton and play crucial roles in various cellular processes, including mitosis and intracellular transport. The property allowing MTs to cater to such diverse roles is attributed to dynamic instability, which is coupled to the hydrolysis of GTP (guanosine-5'-triphosphate) to GDP (guanosine-5'-diphosphate) within the β-tubulin monomers. Understanding the equilibrium dynamics and the structural features of both GDP- and GTP-complexed MT tips, especially at an all-atom level, remains challenging for both experimental and computational methods because of their dynamic nature and the prohibitive computational demands of simulating large, many-protein systems.
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