Crystal structure, DFT and Hirshfeld surface analysis of N-acetyl-t-3-methyl-r-2,c-6-diphenylpiperidine

In the title compound [systematic name: 1-(3-methyl-2,6-diphenylpiperidin-1-yl)ethanone], C20H23NO, the piperidine ring adopts a distorted boat conformation, while the phenyl rings subtend a dihedral angle 65.1 (2)°. In the crystal, molecules are linked by C—H...O hydrogen bonds into chains extending along the b-axis direction. The DFT/B3LYP/6–311 G(d,p) method was used to determine the HOMO–LUMO energy levels. A Hirshfeld surface analysis was conducted to verify the contributions of the different intermolecular interactions, indicating that the important contributions to the crystal packing are from H...H (73.2%), C...H (18.4%) and O...H (8.4%) interactions.

First theoretical probe for alkynyl bridged thiophene modified coumarin nonlinear optical materials with D-π-A and A-π-D-π-A structures

First-principles exploration is very important to molecular design. In this study, geometric structure, intramolecular charge transfer (ICT), energy levels, polar moment, and ultraviolet–visible (UV–Vis) spectroscopy of eight novel and different alkynyl bridged thiophene modified coumarin nonlinear optical molecules with [Formula: see text]-[Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text]-[Formula: see text]-[Formula: see text]-[Formula: see text] structures had been studied by density-functional theory (DFT) calculations within B3LYP hybrid functional using 6-31 [Formula: see text], [Formula: see text] Gaussian type molecular-orbital basis set. This has guiding significance for the design of nonlinear optical molecules and the development of coumarin-based photoelectric molecules.

A Robust Dirichlet Reputation and Trust Evaluation of Nodes in Mobile Ad Hoc Networks

The distributed nature of mobile ad hoc networks (MANETs) presents security challenges and vulnerabilities which sometimes lead to several forms of attacks. To improve the security in MANETs, reputation and trust management systems (RTMS) have been developed to mitigate some attacks and threats arising from abnormal behaviours of nodes in networks. Generally, most reputation and trust systems in MANETs focus mainly on penalising uncooperative network nodes. It is a known fact that nodes in MANETs have limited energy resources and as such, the continuous collaboration of cooperative nodes will lead to energy exhaustion. This paper develops and evaluates a robust Dirichlet reputation and trust management system which measures and models the reputation and trust of nodes in the network, and it incorporates candour into the mode of operations of the RTMS without undermining network security. The proposed RTMS employs Dirichlet probability distribution in modelling the individual reputation of nodes and the trust of each node is computed based on the node’s actual network performance and the accuracy of the second-hand reputations it gives about other nodes. The paper also presents a novel candour two-dimensional trustworthiness evaluation technique that categorises the behaviours of nodes based on their evaluated total reputation and trust values. The evaluation and analyses of some of the simulated behaviours of nodes in the deployed MANETs show that the candour two-dimensional trustworthiness evaluation technique is an effective technique that encourages and caters to nodes that continuously contribute to the network despite the reduction in their energy levels.

DFT and TD-DFT Studies of 1,3,5-Tris (Dipheny1amino) Benzene Derivatives Based Hole Transport Materials: Application for Perovskite Solar Cells

The current study examined a series of 1,3,5-tris (diphenylamino) benzene derivatives used as hole transport materials in perovskite solar cells (HTM1-HTM9). DFT and TD/DFT with the B3LYP/6-311G basis set used for all calculations. The ground state geometry, frontier molecular orbital (FMO), photoelectric properties and reorganization energies and the absorption spectra were investigated. The energy levels of HOMO and LUMO orbitals were calculated for HTM1-HTM9, compared to all of the compounds under investigation and the spiro-OMeTAD, HTM 8 has the lowest HOMO energy level, indicating a favourable overlap with the MAPbI3 perovskite active layer.

Impurity-Induced Magnetization of Graphene

We present a model of impurity-induced magnetization of graphene assuming that the main source of graphene magnetization is related to impurity states with a localized spin. The analysis of solutions of the Schrödinger equation for electrons near the Dirac point has been performed using the model of massless fermions. For a single impurity, the solution of Schrödinger’s equation is a linear combination of Bessel functions. We found resonance energy levels of the non-magnetic impurity. The magnetic moment of impurity with a localized spin was accounted for the calculation of graphene magnetization using the Green’s function formalism. The spatial distribution of induced magnetization for a single impurity is obtained. The energy of resonance states was also calculated as a function of interaction. This energy is depending on the impurity potential and the coupling constant of interaction.

Sex-specific regulation of metabolic health and vertebrate lifespan by AMP biosynthesis

The loss of energy homeostasis seen during aging, is causally linked to multiple age-related pathologies. The AMP-activated protein kinase (AMPK) directly senses cellular energy levels, which are reflected in the ratio between AMP:ATP. However, the genetic regulation of vertebrate aging by the AMPK pathway remains poorly understood. Here, we manipulate ATP production by mutating APRT, a key enzyme in AMP biosynthesis, and extend vertebrate lifespan in a male-specific manner. Using a multi-omics approach, we demonstrate that the APRT mutation restores metabolic plasticity, and identify a distinct transcriptional signature linking mitochondria with the sex-related differences in longevity. Accordingly, APRT mutant cells display a reduction in mitochondrial functions and ATP levels, and an increase in AMPK activity, resembling a persistent state of energy starvation. In-vivo, a fasting-like response was observed exclusively in male mutants, including resistance to a high-fat diet. Finally, intermittent fasting eliminated the longevity benefits mediated by the APRT mutation in males. Together, these data identify AMP biosynthesis as a sex-specific mediator of vertebrate longevity and metabolic health.

Transition to Parenthood, Gender and Well-Being: A Longitudinal Study of the United Kingdom

Previous studies have omitted a dynamic analysis to examine systematically how the transition into parenthood shapes gendered mental health trajectories. This paper adopts a life-course approach to study gender differences in how the transition into parenthood affects multiple indicators of parents’ mental health over time, using high-quality panel data from the ‘UK Household Longitudinal Study’ (2009-2020). Results from fixed effects models with discrete-time trends show that: (1) mothers’ mental health is more largely affected –both positively and negatively– by the transition to parenthood than fathers’; (2) mothers’ overall mental health shows a distinctive positive anticipation and adaptation around childbirth, while fathers show insignificant changes in this transition; (3) becoming a parent decreases the risks of depressive moods for both genders, with long-lasting effects for mothers; (4) stress and energy levels show a deterioration during care-intensive years for both parents, particularly among women; (5) mothers from higher socioeconomic backgrounds experience lower mental health outcomes during care-intensive years. Overall, this study demonstrates the relevance of parenthood transitions in shaping gendered effects on specific mental health outcomes, with distinct implications for women and men over time, as well as across socioeconomic groups.

Atypical dependence of excited exciton energy levels and electron-hole correlation on emission energy in pyramidal InP-based quantum dots

We calculate the spectrum of excited exciton states in application-relevant self-assembled pyramidal quantum dots grown in InAs/InP and InAs/AlGaInAs material systems. These types of dots have been recently shown to combine the emission in the third optical fiber window with low surface density and a reasonable level of in-plane symmetry of emitters, which predestines them for studies on single- and entangled-photon emission and for corresponding applications. The spectrum of optically active excited states is crucial for successful resonant and quasi-resonant excitation of emitters, allowing for conservation of angular momentum and addressing individual selected quantum states. Here, we show that in both types of studied dots, due to their specific morphology of truncated pyramid, the density of excited-state ladder, especially the s–p shell splitting may follow an unconventional dependence on emission energy, opposite to the one typically met in regular quantum dots. We obtain this result via modeling based on available morphological data and calculation within the multi-band $${{\varvec{k}} {\cdot } {\varvec{p}}}$$ k · p envelope-function theory combined with the configuration-interaction method used to calculate exciton states. Then, we explain this observation in purely geometric terms, as a result of an increasing effective quantum confinement width in a pyramid that is progressively cut from the top. Additionally, we show that the inverted trend is also manifested in the amount of electron-hole correlation in the exciton ground state, which also shows an anomalous dependence on emission energy and quantum dot volume.