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Cryogenic transmission electron microscopy has revolutionized structural biology and materials science. To image below liquid nitrogen temperatures, various liquid helium stages have been constructed but have proven to be complex and unstable, making high-resolution imaging challenging. This problem is even more pronounced in side-entry specimen holders common on modern transmission electron microscopes. Here, we introduce an ultracold liquid helium transmission electron microscope side-entry specimen holder, featuring continuous cryogen flow and vibration decoupling. This instrument is compatible with modern aberration-corrected microscopes and achieves sub-25 K base temperature, [Formula: see text]2 mK thermal stability over many hours, and atomic resolution-setting the stage for a new era of cryogenic electron microscopy.
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http://dx.doi.org/10.1073/pnas.2509736122 | DOI Listing |
Proc Natl Acad Sci U S A
September 2025
The Rowland Institute at Harvard, Harvard University, Cambridge, MA 02138.
Cryogenic transmission electron microscopy has revolutionized structural biology and materials science. To image below liquid nitrogen temperatures, various liquid helium stages have been constructed but have proven to be complex and unstable, making high-resolution imaging challenging. This problem is even more pronounced in side-entry specimen holders common on modern transmission electron microscopes.
View Article and Find Full Text PDFSci Prog
September 2025
State Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.
This article addresses the challenges posed by the unique vapor-liquid physical properties of helium, specifically, focusing on the slosh of liquid helium caused by shaking during transportation. A three-dimensional model of a baffle structure is developed to prevent sloshing in the liquid helium portable tanks. Literature-based verification of simulation model via gas-liquid interface data shows <8.
View Article and Find Full Text PDFJ Phys Chem A
September 2025
Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284, United States.
The recent observation of a high-spin Na dimer formed on the surface of liquid helium nanodroplets raises some fundamental questions, as the ground state of Na is known to have zero spin. Is it protected against spontaneous dissociation? What is its binding energy and interatomic distance? Is it stable at a higher temperature? Using calculations based on density functional theory (with and without long-range interaction) and coupled cluster methods, CCSD(T), we show that the bonding in the high-spin Na dimer is governed by van der Waals interaction with binding energy (bond length) varying between -0.030 eV (5.
View Article and Find Full Text PDFJACS Au
August 2025
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Heterogeneous catalytic hydrocracking of polyolefins is a promising approach for the processing of postconsumer plastics, but product quantification methods remain inconsistent across the literature. In systems that generate a large fraction of vapor-phase products, typical product capture methods can result in large carbon balance deficits, exceeding 50%, compromising reported yields and selectivities. Here, we identify the major sources of product loss and develop enhanced capture methods to improve the quantification accuracy.
View Article and Find Full Text PDFPolymers (Basel)
August 2025
European Organization for Nuclear Research (CERN), Esplanade des Particules 1, 1211 Geneva, Switzerland.
Different polyurethanes (PURs) and silicone for potential use in particle accelerators and detectors have been characterized in the uncured state, after curing, and after exposure to ionizing irradiation in ambient air and in liquid helium. The viscosity evolution during processing was measured with a rheometer. Dynamic mechanical analysis (DMA) and Shore A hardness measurements were applied to detect irradiation-induced crosslinking and chain scission effects.
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