The structure of Watson-Crick-type adenine-thymine and guanine-cytosine pairs has been studied by hybrid Monte Carlo (HMC) and path integral hybrid Monte Carlo (PIHMC) simulations with the use of semiempirical PM6-DH+ method in the gas phase. We elucidated the nuclear quantum effect and temperature dependency on the hydrogen-bonded moiety of base pairs. It was shown that the contribution of nuclear quantum effect on the hydrogen-bonded structure is significant not only at low temperature 150 K but also at temperature as high as 450 K. The relative position of hydrogen-bonded proton between two heavy atoms and the nuclear quantum nature of the proton are also shown. Furthermore, we have applied principal component analysis to HMC and PIHMC simulations to analyze the nuclear quantum effect on intermolecular motions. We found that the ratio of Buckle mode (lowest vibrational mode from normal mode analysis) decreases due to the nuclear quantum effect, whereas that of Propeller mode (second lowest vibrational mode) increases. In addition, nonplanar structures of base pairs were found to become stable due to the nuclear quantum effect from two-dimensional free energy landscape along Buckle and Propeller modes.
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http://dx.doi.org/10.1002/jcc.23399 | DOI Listing |
J Chem Phys
January 2025
Microsoft Research AI for Science, 21 Station Road, Cambridge CB1 2FB, United Kingdom.
Variational ab initio methods in quantum chemistry stand out among other methods in providing direct access to the wave function. This allows, in principle, straightforward extraction of any other observable of interest, besides the energy, but, in practice, this extraction is often technically difficult and computationally impractical. Here, we consider the electron density as a central observable in quantum chemistry and introduce a novel method to obtain accurate densities from real-space many-electron wave functions by representing the density with a neural network that captures known asymptotic properties and is trained from the wave function by score matching and noise-contrastive estimation.
View Article and Find Full Text PDFNat Mater
January 2025
School of Physics, Zhejiang University, Hangzhou, China.
In ordered magnets, the elementary excitations are spin waves (magnons), which obey Bose-Einstein statistics. Similarly to Cooper pairs in superconductors, magnons can be paired into bound states under attractive interactions. The Zeeman coupling to a magnetic field is able to tune the particle density through a quantum critical point, beyond which a 'hidden order' is predicted to exist.
View Article and Find Full Text PDFSmall
January 2025
MEET, Battery Research Center, University of Muenster, 48149, Muenster, Germany.
Rechargeable lithium-ion batteries (LIBs) are critical for enabling sustainable energy storage. The capacity of cathode materials is a major limiting factor in the LIB performance, and doping has emerged as an effective strategy for enhancing the electrochemical properties of nickel-rich layered oxides such as NCM811. In this study, boron is homogeneously incorporated into the tetrahedral site of NCM811 through co-precipitation, leading to an inductive effect on transition metal (TM)-O-B bonds that delayed structural collapse and reduced oxygen release.
View Article and Find Full Text PDFTech Vasc Interv Radiol
December 2024
Department of Interventional Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, FL; Department of Interventional Radiology, Miami Cardiac and Vascular Institute, Baptist Health South Florida, Miami, FL; Department of Radiology and Nuclear Medicine, Amsterdam UMC, Location VUmc, Cancer Center Amsterdam, AMS, The Netherlands. Electronic address:
Robotic systems for minimally invasive procedures, particularly in interventional oncology, have advanced significantly, especially for percutaneous interventions guided by CT, Cone-beam CT, and MRI. These systems, which include needle-guiding and needle-driving robots, enhance the precision of procedures like biopsy and tumor ablation. Needle-guiding robots plan and align the needle, while needle-driving robots autonomously advance it, improving needle placement accuracy, enabling out-of-plane insertion, and reducing radiation exposure.
View Article and Find Full Text PDFSci Rep
January 2025
Molecular Modeling and Simulation Team, Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba City, Chiba, 263-8555, Japan.
Sequence-dependent mechanical properties of DNA could play essential roles in nuclear processes by affecting histone-DNA interactions. Previously, we found that the DNA entry site of the first nucleosomes from the transcription start site (+ 1 nucleosome) in budding yeast enriches AA/TT steps, but not the exit site, and the biased presence of AA/TT in the entry site was associated with the transcription levels of yeast genes. Because AA/TT is a rigid dinucleotide step, we considered that AA/TT causes DNA unwrapping.
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