Computer Simulation of the Semiconductor Nanoelectromechanical Systems AIIBIVAs2 Stability after Attosecond Impulse Exposure

The article deals with computer modeling of responses of multicomponent semiconductor nanoelectromechanical systems of arsenides to an attosecond radiation pulse at cryogenic (T1=77 K) and standard temperatures (T2=298 K). Kinetic curves of relaxation processes in ternary semiconductor nanolayers CdSiAs2, CdGeAs2, ZnSiAs2, ZnGeAs2, and nanolayers of variable composition CdSi1-xGex As2, ZnSi1-xGexAs2, Cd1-xZnxSiAs2 и Cd1-xZnxGeAs2 are obtained. This research reveals the differences in the average relaxation energy of nanolayers that depend on temperature and the amplitudes of energy fluctuations, and the time of reaching the plateau. A comparison with relaxation processes taking place at absolute zero temperatures is demonstrated. The radial distribution functions of atoms in the system before and after relaxation processes caused by impulsive action on the system of atoms in the semiconductor layer are considered. The modification of the peaks corresponding to the coordination spheres of atomic distribution depending on the composition of the nanolayer is described. The regularities of relaxation changes of the first order coordination spheres, as well as the regularities of relaxation destructions of the second and the third order coordination spheres at cryogenic and standard temperatures are revealed.

A continuum membrane model predicts curvature sensing by helix insertion

Protein domains, such as ENTH (Epsin N-terminal homology) and BAR (bin/amphiphysin/rvs), contain amphipathic helices that drive preferential binding to curved membranes. However, predicting how the physical parameters of these domains control this ‘curvature sensing’ behavior is challenging due to the local membrane deformations generated by the nanoscopic helix on the surface of a large sphere. To overcome this challenge, we here use a deformable continuum model that accounts for the physical properties of the membrane and the helix insertion to predict curvature sensing behavior and is in good agreement with existing experimental data. Specifically, we show that the insertion can be modeled as a local change to the membrane’s spontaneous curvature,. Using physically reasonable ranges of the membrane bending modulus к, and a of ∼0.2-0.3 nm-1, this approach provides excellent agreement with the energetics extracted from experiment. For small vesicles with high curvature, the insertion lowers the membrane energy by relieving strain on a membrane that is far from its preferred curvature of zero. For larger vesicles with low curvature, however, the insertion has the inverse effect, de-stabilizing the membrane by introducing more strain. The membrane energy cannot be directly predicted analytically, due to shape changes from surface relaxation around the anisotropic insertion. We formulate here an empirical expression that captures numerically calculated membrane energies as a function of both basic membrane properties (bending modulus к and radius R) as well as stresses applied by the inserted helix ( and area Ains). We show that the shape relaxation energy has a similar magnitude to the insertion energy, with a strong nonlinear dependence on . We therefore predict how these physical parameters will alter the energetics of helix binding to curved vesicles, which is an essential step in understanding their localization dynamics during membrane remodeling processes.

Predicting Carbonyl Excitation Energies Efficiently Using EOM-CC Trends

We approach the problem of predicting excitation energies of diverse, larger (5–6 carbons) carbonyl species central to earth’s tropospheric chemistry. Triples contributions are needed for the vertical excitation energy (E^vert), while EOM-CCSD//TD-DFT calculations provide acceptable estimates for the S₁ relaxation energy (E^relax), and (TD-)DFT suffices for the S₀ → S₁ zero-point vibration energy correction (∆E^ZPVE). <div><br></div><div>Perturbative triples corrections deliver E^vert values close in accuracy to full iterative triples EOM-CC calculations. The error between EOM-CCSD and triples-corrected E vert values appears to be systematic and can be accounted for with scaling factors. However, saturated and α,β-unsaturated carbonyls must be treated separately. Double-hybrid S₀ minima can be used to calculate E^vert with negligible loss in accuracy, relegating the O(N⁵) expense of CCSD to only single-point energy and excitation calculations. </div><div><br></div><div>This affordable protocol can be applied to all volatile carbonyl species. E⁰⁻⁰ predictions do overestimate measured values by ∼8 kJ/mol due to a lack of triples contribution in E relax, but this overestimation is systematic and the mean unsigned error is within 4 kJ/mol once this is accounted for.</div>

Predicting Carbonyl Excitation Energies Efficiently Using EOM-CC Trends

We approach the problem of predicting excitation energies of diverse, larger (5–6 carbons) carbonyl species central to earth’s tropospheric chemistry. Triples contributions are needed for the vertical excitation energy (E^vert), while EOM-CCSD//TD-DFT calculations provide acceptable estimates for the S₁ relaxation energy (E^relax), and (TD-)DFT suffices for the S₀ → S₁ zero-point vibration energy correction (∆E^ZPVE). <div><br></div><div>Perturbative triples corrections deliver E^vert values close in accuracy to full iterative triples EOM-CC calculations. The error between EOM-CCSD and triples-corrected E vert values appears to be systematic and can be accounted for with scaling factors. However, saturated and α,β-unsaturated carbonyls must be treated separately. Double-hybrid S₀ minima can be used to calculate E^vert with negligible loss in accuracy, relegating the O(N⁵) expense of CCSD to only single-point energy and excitation calculations. </div><div><br></div><div>This affordable protocol can be applied to all volatile carbonyl species. E⁰⁻⁰ predictions do overestimate measured values by ∼8 kJ/mol due to a lack of triples contribution in E relax, but this overestimation is systematic and the mean unsigned error is within 4 kJ/mol once this is accounted for.</div>

Predicting Carbonyl Excitation Energies Efficiently Using EOM-CC Trends

We approach the problem of predicting excitation energies of diverse, larger (5–6 carbons) carbonyl species central to earth’s tropospheric chemistry. Triples contributions are needed for the vertical excitation energy (E^vert), while EOM-CCSD//TD-DFT calculations provide acceptable estimates for the S₁ relaxation energy (E^relax), and (TD-)DFT suffices for the S₀ → S₁ zero-point vibration energy correction (∆E^ZPVE). <div><br></div><div>Perturbative triples corrections deliver E^vert values close in accuracy to full iterative triples EOM-CC calculations. The error between EOM-CCSD and triples-corrected E vert values appears to be systematic and can be accounted for with scaling factors. However, saturated and α,β-unsaturated carbonyls must be treated separately. Double-hybrid S₀ minima can be used to calculate E^vert with negligible loss in accuracy, relegating the O(N⁵) expense of CCSD to only single-point energy and excitation calculations. </div><div><br></div><div>This affordable protocol can be applied to all volatile carbonyl species. E⁰⁻⁰ predictions do overestimate measured values by ∼8 kJ/mol due to a lack of triples contribution in E relax, but this overestimation is systematic and the mean unsigned error is within 4 kJ/mol once this is accounted for.</div>

Compact Trap-Assisted-Tunneling Model for Line Tunneling Field-Effect-Transistor Devices

Trap-assisted-tunneling (TAT) is a well-documented source of severe subthreshold degradation in tunneling field-effect-transistors (TFET). However, the literature lacks in numerical or compact TAT models applied to TFET devices. This work presents a compact formulation of the Schenk TAT model that is used to fit experimental drain-source current (Ids) versus gate-source voltage (Vgs) data of an L-shaped and line tunneling type TFET. The Schenk model incorporates material-dependent fundamental physical constants that play an important role in influencing the TAT generation (GTAT) including the lattice relaxation energy, Huang–Rhys factor, and the electro-optical frequency. This makes fitting any experimental data using the Schenk model physically relevant. The compact formulation of the Schenk TAT model involved solving the potential profile in the TFET and using that potential profile to calculate GTAT using the standard Schenk model. The GTAT was then approximated by the Gaussian distribution function for compact implementation. The model was compared against technology computer-aided design (TCAD) results and was found in reasonable agreement. The model was also used to fit an experimental device’s Ids–Vgs characteristics. The results, while not exactly fitting the experimental data, follow the general experimental Ids–Vgs trend reasonably well; the subthreshold slope was loosely similar to the experimental device. Additionally, the ON-current, especially to make a high drain-source bias model accurate, can be further improved by including effects such as electrostatic degradation and series resistance.

Conformational state switching and pathways of chromosome dynamics in cell cycle

Cell cycle is a process and function of a cell with different phases essential for cell growth, proliferation, and replication. Cell cycle depends on the structure and dynamics of the underlying DNA molecule, which underpins the genome function. A microscopic structural-level understanding of how genome or its functional module chromosome performs the cell cycle in terms of large-scale conformational transformation between different phases such as the interphase and the mitotic phase is still challenging. Here, we develop a non-equilibrium excitation-relaxation energy landscape-switching model to quantify the underlying chromosome conformational transitions through (de-)condensation for a complete microscopic understanding of the cell cycle. We show that the chromosome conformational transition mechanism from the interphase to the mitotic phase follows a two-stage scenario, in good agreement with the experiments. In contrast, the mitotic exit pathways show the existence of an over-expanded chromosome that recapitulates the chromosome in the experimentally identified intermediate state at the telophase. We find the conformational pathways are heterogeneous and irreversible, as a result of the non-equilibrium dynamics of the cell cycle from both structural and kinetic perspectives. We suggest that the irreversibility is mainly due to the distinct participation of the ATP-dependent structural maintenance of chromosomal protein complexes during the cell cycle. Our findings provide crucial insights into the microscopic molecular structural and dynamical physical mechanism for the cell cycle beyond the previous more macroscopic descriptions. Our non-equilibrium landscape framework is general and applicable to study diverse non-equilibrium physical and biological processes such as active matter, differentiation/development and cancer.

Cross-relaxation energy transfer between the Er3+ ions in vitreous arsenic chalcogenide

In this paper, we study widely investigated photoluminescent properties of [Formula: see text] compounds in the near-infrared ranges. The increase of the infrared luminescence intensity with increasing [Formula: see text] concentration can be attributed to the cross-relaxation process between the activator ions.