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[IEEE 2018 XIV International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE) - Novosibirsk, Russia (2018.10.2-2018.10.6)] 2018 XIV International Scientific-Technical Conference on Actual Problems of Electronics Instrument Engineering (APEIE) - Students' Project Developments of Wave Optics Virtual Labs
摘要： The author organized the project activity of computer modeling in teaching physics of IT students. The students' teams develop software products – virtual laboratories. The article presents some examples of the students' developments of virtual laboratories of Wave Optics.
关键词： computer modeling of physical processes,project training,virtual labs
更新于2025-09-23 15:22:29
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Chirality-dependent growth of self-assembled diphenylalanine microtubes
摘要： The difference in crystal structure and growth kinetics of microtubes formed from L- and D- enantiomers of diphenylalanine dipeptide is investigated both experimentally and theoretically by computer simulation. The microtubes of L- and D- enantiomers grown simultaneously and under identical experimental conditions possess different crystallographic space groups, have essential difference in sizes and demonstrate different growth kinetics. Computer simulation by molecular mechanics methods revealed a fundamental difference in the interaction between structural units of microtubes of different chiralities. A model describing chirality-dependent growth of microtubes is proposed.
关键词： Growth kinetics,Enantiomers,Dipeptide,Computer modeling,Nanotubes,Self-assembly
更新于2025-09-16 10:30:52
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Solubility and H-bonding of poly(vinylidene fluoride) copolymers in carbonyl liquids: Experiment and molecular simulation
摘要： H-bond formation among fluoropolymers and carbonyl solvents was studied by microcalorimetry and quantum chemistry simulation. Typically, fluorine atoms in organic molecules depress their ability to molecular interactions with solvents. Meanwhile, it is not the case if fluoropolymer is dissolved in carbonyl solvent. Among other organic solvents carbonyl-containing liquids are characterized by very large exothermic effects of dissolution of vinylidene fluoride copolymers which are typical for the systems with electron-donor-acceptor complexes. The enthalpy of mixing in the entire concentration range was determined for P(VDF-co-HFP) and P(VDF-co-CTFE) solutions in ethyl acetate and Flory-Huggins parameter was evaluated. It was ?1.31, which means very strong interaction among solvent and vinylidene fluoride monomer units. This interaction was modeled by quantum chemistry semi-empirical AM1, PM3, PM5 and density functional B88-PW91, B88-LYP, D-VWN calculations for the complexes between acetone or ethyl acetate and vinylidene fluoride tetramer. The heat of formation of the complex from its components was found around ?18 kJ/mol. The binding site of the complex was a macrocyclic structure which comprised H-bonds between carbonyl and methylene hydrogens of vinylidene fluoride backbone, and weaker H-bonds between fluorine atoms and methyl hydrogen. The analysis of molecular orbitals of the complex reveals extended electron delocalization across the binding center.
关键词： Calorimetry,H-bonding,Computer modeling,Solubility of vinylidene fluoride copolymers
更新于2025-09-10 09:29:36
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Virtual Tissue Engineering and Optic Pathways: Plotting the Course of the Axons in the Retinal Nerve Fiber Layer
摘要： As part of a larger project on virtual tissue engineering of the optic pathways, we describe the conditions that guide axons extending from the retina to the optic nerve head and formulate algorithms that meet such conditions. To find the entrance site on the optic nerve head of each axon, we challenge the fibers to comply with current models of axonal pathfinding. METHODS. First, we build a retinal map using a single type of retinal ganglion cell (RGC) using density functions from the literature. Dendritic arbors are equated to receptive fields. Shape and size of retinal surface and optic nerve head (ONH) are defined. A computer model relates each soma to the corresponding entry point of its axon into the optic disc. Weights are given to the heuristics that guide the preference entry order in the nerve. RESULTS. Retinal ganglion cells from the area centralis saturate the temporal section of the disc. Retinal ganglion cells temporal to the area centralis curve their paths surrounding the fovea; some of these cells enter the disc centrally rather than peripherally. Nasal regions of the disc receive mixed axons from the far periphery of the temporal hemiretina, together with axons from the nasal half. The model plots the course of the axon using Bezier curves and compares them with clinical data, for a coincidence level of 86% or higher. CONCLUSIONS. Our model is able to simulate basic data of the early optic pathways including certain singularities and to mimic mechanisms operating during development, such as timing and fasciculation.
关键词： optic pathways,course of axons,retinal ganglion cell layer,computer modeling
更新于2025-09-04 15:30:14