Electronic Structure and Magnetism of Pristine, Defected, and Strained Ti2N MXene

From first principles electronic structure calculations, we unravel the evolution of structural, electronic, and magnetic properties of pristine, defected, and strained titanium nitride MXene with different functional groups (-F, -O, -H, and -OH). The formation and cohesive energies reveal their chemical stability. The MAX phase and defect free functionalized MXenes are metallic except for oxygen terminated (Ti 2 NO 2 ) one which is 100% spin polarized half-metallic ferromagnet. The spin-orbit coupling significantly influences the bare MXene (Ti 2 N) to exhibit Dirac topology and band inversion near the high symmetry directions and Fermi level. The strain effect sways the Fermi level thereby shifting it toward lower energy state under compression and toward higher energy state under tensile strain in Ti 2 NH 2 . The Ti 2 NO 2 exhibits exotic electronic structure and magnetic states not only in pristine but also in strained and defected structures. Its half-metallic nature changes to semi-metallic under 1% compression and it is completely destroyed under 2% compression. In single vacancy defect, its band structure remarkably transforms from half-metallic to semi-conducting with large band gap in 12.5% Ti, weakly semi-conducting in 5.5% Ti, and semi-metallic in 12.5% O. The 25% N defect changes it’s half-metallic characteristic to metallic. Further, the 12.5% Co substitution preserves it’s half-metallic character, whereas Mn substitution allows it to convert half-metallic characteristic into weak semi-metallic characteristic preserving ferromagnetism. However, Cr substitution converts half-metallic ferromagnetic state to half-metallic anti-ferromagnetic state. The understanding made here on collective structural stability, and electronic band structure, and magnetic phenomena in novel 2D Ti 2 N derived MXenes open up their possibility in designing them for synthesis and thereby taking to applications.

Negative tension controls stability and structure of intermediate filament networks

Networks, whose junctions are free to move along the edges, such as two-dimensional soap froths and membrane tubular networks of endoplasmic reticulum are intrinsically unstable. This instability is a result of a positive tension applied to the network elements. A paradigm of networks exhibiting stable polygonal configurations in spite of the junction mobility, are networks formed by bundles of Keratin Intermediate Filaments (KIFs) in live cells. A unique feature of KIF networks is a, hypothetically, negative tension generated in the network bundles due to an exchange of material between the network and an effective reservoir of unbundled filaments. Here we analyze the structure and stability of two-dimensional networks with mobile three-way junctions subject to negative tension. First, we analytically examine a simplified case of hexagonal networks with symmetric junctions and demonstrate that, indeed, a negative tension is mandatory for the network stability. Another factor contributing to the network stability is the junction elastic resistance to deviations from the symmetric state. We derive an equation for the optimal density of such networks resulting from an interplay between the tension and the junction energy. We describe a configurational degeneration of the optimal energy state of the network. Further, we analyze by numerical simulations the energy of randomly generated networks with, generally, asymmetric junctions, and demonstrate that the global minimum of the network energy corresponds to the irregular configurations.

Shear strain-induced structure relaxation of Ni Σ17 [110](223) grain boundary: A molecular dynamics simulation

The stabilization of grain boundaries (GBs) is beneficial for improving the stability and mechanical properties of nanocrystalline (NC) metals. Molecular dynamics (MD) calculations were performed to investigate the shear response of Ni [Formula: see text]17 [110](223) symmetrical tilt GB. It was found that under the action of shear, the nucleation and evolution of the GB source Shockley partial dislocations ultimately result in the low-energy-state transformation of the GB structure units (SUs). However, the Ag atom contained in the GB increases the shear stress and strain required for the GB relaxation, and the strain range for the GB relaxation is expanded, indicating the inhibitory effect of the Ag atom on the structural relaxation of Ni [Formula: see text]17 [110](223) GB. As the temperature increases from 10 K to 250 K, the structural relaxation of Ni [Formula: see text]17 [110](223) GB becomes easier to proceed. In addition to segregation-induced GB stabilization, strain-induced GB relaxation and the roles of foreign atom and temperature clarified in this work could provide several new entry points for stabilizing high-energy GBs.

Radiative and Non-Radiative Decay Pathways in Carbon Nanodots toward Bioimaging and Photodynamic Therapy

The origin and classification of energy states, as well as the electronic transitions and energy transfers associated with them, have been recognized as critical factors for understanding the optical properties of carbon nanodots (CNDs). Herein, we report the synthesis of CNDs in an optimized process that allows low-temperature carbonization using ethanolamine as the major precursor and citric acid as an additive. The results obtained herein suggest that the energy states in our CNDs can be classified into four different types based on their chemical origin: carbogenic core states, surface defective states, molecular emissive states, and non-radiative trap states. Each energy state is associated with the occurrence of different types of emissions in the visible to near-infrared (NIR) range and the generation of reactive oxygen species (ROS). The potential pathways of radiative/non-radiative transitions in CNDs have been systematically studied using visible-to-NIR emission spectroscopy and fluorescence decay measurements. Furthermore, the bright photoluminescence and ROS generation of these CNDs render them suitable for in vitro imaging and photodynamic therapy applications. We believe that these new insights into the energy states of CNDs will result in significant improvements in other applications, such as photocatalysis and optoelectronics.

Automation of workover candidate ranking processes at Krasnoleninskoye oil and gas condensate field

Background. Workovers (WO) are the main EOR tool at Krasnoleninskoye reservoirs. Therefore, the issue of increasing the reliability of technological and economic performance when planning various types of workovers is urgent. This is due to the complexity of selecting well candidates, the lack of a comprehensive methodology for assessing the short-term and long-term potential of wells, large WO scopes, as well as declining WO performance associated with the reduction of reserves, deterioration of the energy state of the reservoirs, and advancement of the injected water front. The purpose of the study is to create mathematical tools that will reduce the time of well-candidates selection for various types of workovers and to improve the WO quality for entire field. The paper describes methods of automated selection of well candidates that were successfully applied in the conditions of the field of interest, namely graphical and mathematical tools. The mathematical one has been created based on the correlation-regression analysis of the actual implementation of stimulation methods in various geological-field conditions in Microsoft Excel 2010 with Visual Basic for Applications (VBA). The graphical tool has been generated on the basis of all historical field data verified and processed using methods of primary statistical analysis in RN-KIN software. The study resulted in a technique that was selected and tested in the conditions of Krasnoleninskoye oil and gas condensate field. The process of introducing the developed approaches to the search for well candidates for various types of workovers in the field was accompanied by updating, analysis of results, and cyclic training of the system. A methodological approach has been developed, including the combination of several methods for selecting well candidates for various types of workovers. A combination of statistical and graphical methods made it possible to significantly improve the reliability of WO candidates selection and therefore to reduce the share of uneconomic workovers by 12 % in the period from 2017 to 2020. As part of the study, a script has been developed that automatically computes the rank of a well-candidate which significantly reduces time costs and allows to quickly evaluate the “best” workover candidates.

Future Trends and Aging Analysis of Battery Energy Storage Systems for Electric Vehicles

The increase of electric vehicles (EVs), environmental concerns, energy preservation, battery selection, and characteristics have demonstrated the headway of EV development. It is known that the battery units require special considerations because of their nature of temperature sensitivity, aging effects, degradation, cost, and sustainability. Hence, EV advancement is currently concerned where batteries are the energy accumulating infers for EVs. This paper discusses recent trends and developments in battery deployment for EVs. Systematic reviews on explicit energy, state-of-charge, thermal efficiency, energy productivity, life cycle, battery size, market revenue, security, and commerciality are provided. The review includes battery-based energy storage advances and their development, characterizations, qualities of power transformation, and evaluation measures with advantages and burdens for EV applications. This study offers a guide for better battery selection based on exceptional performance proposed for traction applications (e.g., BEVs and HEVs), considering EV’s advancement subjected to sustainability issues, such as resource depletion and the release in the environment of ozone and carbon-damaging substances. This study also provides a case study on an aging assessment for the different types of batteries investigated. The case study targeted lithium-ion battery cells and how aging analysis can be influenced by factors such as ambient temperature, cell temperature, and charging and discharging currents. These parameters showed considerable impacts on life cycle numbers, as a capacity fading of 18.42%, between 25–65 °C was observed. Finally, future trends and demand of the lithium-ion batteries market could increase by 11% and 65%, between 2020–2025, for light-duty and heavy-duty EVs.

NADH inhibition of SIRT1 links energy state to transcription during time-restricted feeding

In mammals, circadian rhythms are entrained to the light cycle and drive daily oscillations in levels of NAD+, a cosubstrate of the class III histone deacetylase sirtuin 1 (SIRT1) that associates with clock transcription factors. Although NAD+ also participates in redox reactions, the extent to which NAD(H) couples nutrient state with circadian transcriptional cycles remains unknown. Here we show that nocturnal animals subjected to time-restricted feeding of a calorie-restricted diet (TRF-CR) only during night-time display reduced body temperature and elevated hepatic NADH during daytime. Genetic uncoupling of nutrient state from NADH redox state through transduction of the water-forming NADH oxidase from Lactobacillus brevis (LbNOX) increases daytime body temperature and blood and liver acyl-carnitines. LbNOX expression in TRF-CR mice induces oxidative gene networks controlled by brain and muscle Arnt-like protein 1 (BMAL1) and peroxisome proliferator-activated receptor alpha (PPARα) and suppresses amino acid catabolic pathways. Enzymatic analyses reveal that NADH inhibits SIRT1 in vitro, corresponding with reduced deacetylation of SIRT1 substrates during TRF-CR in vivo. Remarkably, Sirt1 liver nullizygous animals subjected to TRF-CR display persistent hypothermia even when NADH is oxidized by LbNOX. Our findings reveal that the hepatic NADH cycle links nutrient state to whole-body energetics through the rhythmic regulation of SIRT1.

Investigation Into Magnetic Reconnection Formation on Propellant Ignition in Electrical Explosion

In magnetic reconnection, magnetic lines break and reconnect to change their topology to a lower-energy state. This process can liberate stored magnetic field energy and accelerate particles during unsteady explosive events. Here, we report the observations of the magnetic reconnection and kink instability of plasma jet in single wire electrical explosion and their effect on propellant ignition. The results showed that the initial velocity of plasma was ∼2,000 m/s, and when the magnetic reconnection occurred, the velocity increased by ∼400–∼2,400 m/s. The evaluated Alfvén velocity was ∼500 m/s, the Alfvén time was ∼20 µs, and the Lundquist number S = 1.7 × 107. Based on these experimental results and model, the three-dimensional magnetic field topology and its evolution process was evaluated and presented. Furthermore, the magnetic reconnection occurred when its curvature reached a certain value due to the fact that the motion of the current sheet changes the topology of the magnetic field, and then, the plasma jet was accelerated and exhausted. The plasma jet angle was ∼50° in experiment 1, and it was consistent with the calculated results. The resulting magnetic reconnection plays an important role in propellant ignition, which enhances the ignition ability of wire electrical explosion. Furthermore, the results represent a key step towards resolving one of the most important problems of plasma physics and can be used to improve the understanding of wire array explosion and propellant ignition.

Towards an ecological definition of sepsis: a viewpoint

In critically ill patients with sepsis, there is a grave lack of effective treatment options to address the illness-defining inappropriate host response. Currently, treatment is limited to source control and supportive care, albeit with imminent approval of immune modulating drugs for COVID-19-associated lung failure the potential of host-directed strategies appears on the horizon. We suggest expanding the concept of sepsis by incorporating infectious stress within the general stress response of the cell to define sepsis as an illness state characterized by allostatic overload and failing adaptive responses along with biotic (pathogen) and abiotic (e.g., malnutrition) environmental stress factors. This would allow conceptualizing the failing organismic responses to pathogens in sepsis with an ancient response pattern depending on the energy state of cells and organs towards other environmental stressors in general. Hence, the present review aims to decipher the heuristic value of a biological definition of sepsis as a failing stress response. These considerations may motivate a better understanding of the processes underlying “host defense failure” on the organismic, organ, cell and molecular levels.