Slab geometric boundary conditions are applied in the molecular dynamics simulation of a simple membrane-channel system. The results of the simulation were compared to those of an analogous system using normal three-dimensional periodic boundary conditions. Analysis of the dynamics and electrostatics of the system show that slab geometric periodicity eliminates the artificial bulk water orientational polarization that is present while using normal three-dimensional periodicity. Furthermore, even though the water occupancy and volume of our simple channel is the same when using either method, the electrostatic properties are considerably different when using slab geometry. In particular, the orientational polarization of water is seen to be different in the interior of the channel. This gives rise to a markedly different electric field within the channel. We discuss the implications of slab geometry for the future simulation of this type of system and for the study of channel transport properties.
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http://dx.doi.org/10.1016/S0006-3495(03)74458-0 | DOI Listing |
Materials (Basel)
December 2024
Centre of Materials and Building Technologies (C-MADE), Department of Civil Engineering and Architecture, University of Beira Interior (UBI), 6201-001 Covilhã, Portugal.
The paper examines the impact of passive restraint on fire-induced spalling in concrete, utilizing a concrete mixture to minimize compositional variability. A variety of specimen geometries was prepared, including standard cubes and cylinders for the determination of mechanical properties and slabs of different dimensions for fire spalling tests conducted under controlled conditions. A top-opening Dragon furnace, which applies ISO 834-1 fire curves, was used to evaluate the influence of "cold rim" boundaries, where slab edges were insulated to create thermal restraint.
View Article and Find Full Text PDFAsian Pac J Cancer Prev
December 2024
Department of Physics, Lovely Professional University, Phagwara, India.
Aim: To study the dosimetric behavior of dose computational algorithms in inhomogeneous medium using CMS XiO and MONACO treatment planning system (TPS) for 4 megavoltage (MV), 6 MV and 15 MV photon beam energies.
Material And Methods: Styrofoam blocks of thickness 1.90 cm, 3.
Magn Reson Med
November 2024
Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.
Purpose: To overcome the major challenges in diffusion MRI (dMRI) acquisition, including limited SNR, distortion/blurring, and susceptibility to motion artifacts.
Theory And Methods: A novel Romer-EPTI technique is developed to achieve SNR-efficient acquisition while providing distortion-free imaging, minimal spatial blurring, high motion robustness, and simultaneous multi-TE imaging. It introduces a ROtating-view Motion-robust supEr-Resolution technique (Romer) combined with a distortion/blurring-free Echo Planar Time-resolved Imaging (EPTI) readout.
Invest Ophthalmol Vis Sci
November 2024
Department of Internal Medicine, Healthcare Research Institute, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Republic of Korea.
Purpose: To elucidate the mechanism underlying changes in choroidal metrics (choroidal thickness [CT], choroidal vascularity index [CVI], and choriocapillaris [CC] flow deficit [FD]) observed in diabetic retinopathy (DR) and examine the association of choroidal metrics with both retinal vessel geometry and optical coherence tomography angiography (OCTA) metrics.
Methods: Overall, 133 eyes of 133 patients were analyzed retrospectively. Retinal vessel geometry parameters were assessed using semiautomated software.
PLoS One
November 2024
Department of Biology, University of Naples "Federico II", Naples, Italy.
Subduction of the Cocos and Nazca oceanic plates beneath the Caribbean plate drives the upward movement of deep fluids enriched in carbon, nitrogen, sulfur, and iron along the Central American Volcanic Arc (CAVA). These compounds fuel diverse subsurface microbial communities that in turn alter the distribution, redox state, and isotopic composition of these compounds. Microbial community structure and functions vary according to deep fluid delivery across the arc, but less is known about how microbial communities differ along the axis of a convergent margin as geological features (e.
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