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The solvent can occupy up to ∼70% of macromolecular crystals, and hence, having models that predict solvent distributions in periodic systems could improve the interpretation of crystallographic data. Yet, there are few implicit solvent models applicable to periodic solutes, and crystallographic structures are commonly solved assuming a flat solvent model. Here, we present a newly developed periodic version of the 3D-reference interaction site model (RISM) integral equation method that is able to solve efficiently and describe accurately water and ion distributions in periodic systems; the code can compute accurate gradients that can be used in minimizations or molecular dynamics simulations. The new method includes an extension of the Ornstein-Zernike equation needed to yield charge neutrality for charged solutes, which requires an additional contribution to the excess chemical potential that has not been previously identified; this is an important consideration for nucleic acids or any other charged system where most or all the counter- and co-ions are part of the "disordered" solvent. We present several calculations of proteins, RNAs, and small molecule crystals to show that x-ray scattering intensities and the solvent structure predicted by the periodic 3D-RISM solvent model are in closer agreement with the experiment than are intensities computed using the default flat solvent model in the refmac5 or phenix refinement programs, with the greatest improvement in the 2 to 4 Å range. Prospects for incorporating integral equation models into crystallographic refinement are discussed.
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http://dx.doi.org/10.1063/5.0070869 | DOI Listing |
Behav Res Methods
September 2025
Department of Psychology, University of Basel, Basel, Switzerland.
Over the past several decades, decision-making research has been dominated by the study of binary choice tasks, with key models assuming that people remain equally cautious regardless of how long they have spent on the choice problem. Recent research has begun to place a greater focus on studying tasks with a continuous-response scale, as well as models that allow for decreases in caution over decision time; however, these research topics have remained separate from one another. For instance, proposed models of continuous-response scales have assumed constant caution over time, and studies investigating whether caution decreases over time have focused on binary choice tasks.
View Article and Find Full Text PDFBrain Res Bull
September 2025
Department of Psychiatry, Keck School of Medicine, University of Southern California, Los Angeles, CA; Institute for the Developing Mind, Children's Hospital Los Angeles, Los Angeles, CA.
We propose a Biophysically Restrained Analog Integrated Neural Network (BRAINN), an analog electrical network that models the dynamics of brain function. The network interconnects analog electrical circuits that simulate two tightly coupled brain processes: (1) propagation of an action potential, and (2) regional cerebral blood flow in response to the metabolic demands of signal propagation. These two processes are modeled by two branches of an electrical circuit comprising a resistor, a capacitor, and an inductor.
View Article and Find Full Text PDFContemp Clin Trials
September 2025
Quantitative Sciences Unit, Stanford School of Medicine, United States of America.
Background: Non-collegiate young adults engage in high rates of heavy drinking but are less likely to access alcohol-related counseling or treatment. Peers play a significant role in shaping drinking behavior, yet few interventions target close peer influence in this population.
Methods: This two-arm randomized controlled trial will enroll 300 young adults aged 18-25 who report 2+ heavy drinking days (HDD; defined as 4+ drinks for a woman and 5+ drinks for a man) in the past 30 days and are not enrolled in college.
Front Nutr
August 2025
Thaer-Institute-Div. Urban Plant Ecophysiology, Humboldt-Universität zu Berlin, Berlin, Germany.
Background: Changes in consumer food choices have been associated with transformation in the food environment. Despite the direct impact of consumers' food choices on their diet and health outcomes, there is a lack of comprehensive evidence regarding how various factors within the food environment impact these choices.
Methods: This study uses the Theory of Planned Behavior to examine how socio-psychological factors in the food environment influence consumers' healthy food choices.
ACS Electrochem
September 2025
Liquid Sunlight Alliance, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Reaction rate coefficients for electron-transfer processes at the electrode-electrolyte interface are commonly estimated by using the Butler-Volmer equation, but their values are inaccurate beyond a few tenths of volts of overpotential. The Marcus-Hush-Chidsey (MHC) formalism yields correct asymptotic behavior of the rate coefficients vs applied overpotential but has complex dependencies on the redox system's intrinsic parameters, which can be difficult to model or measure. In this work, we bridge the two kinetics formalisms to estimate the reorganization energy, one of the important parameters for the MHC formalism, and investigate its dependence on other intrinsic parameters such as activation barriers, electronic coupling strength, and the density of states of the electrode surface.
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