Enhancing the ultrafast third order nonlinear optical response by charge transfer in VSe2-reduced graphene oxide hybrid

Nonlinear optical phenomena play a critical role in understanding microscopic light-matter interactions and have far-reaching applications across various fields, such as biosensing, quantum information, optical switching, and all-optical data processing. Most of these applications require materials with high third-order absorptive and refractive optical nonlinearities. However, most materials show weak nonlinear optical responses due to their perturbative nature and often need to be improved for practical applications. Here, we demonstrate that the charge donor-acceptor hybrid of VSe2-reduced graphene oxide (rGO) hybrid exhibits enhanced ultrafast third-order absorptive and refractive nonlinearities compared to the pristine systems, at least by one order of magnitude. Through density functional theory and Bader charge analysis, we elucidate the strong electronic coupling in the VSe2-rGO hybrid, involving the transfer of electrons from VSe2 to rGO. Steady-state and time-resolved photoluminescence (PL) measurements confirm the electronic coupling and charge transfer. Furthermore, we fabricate an ultrafast optical limiter device with better performance parameters, such as an onset threshold of 2.5 mJ cm-2 and differential transmittance of 0.42

Evaluation of Incisor Inclination on Smile on Lateral Profile

Background: Smile is the key that fits the lock of every heart. Objective: The aim of the study was to evaluate inclination of maxillary incisors on smile aesthetics in relation with the profile view and to evaluate the perception and awareness of dentists, orthodontists, lay people and students towards smile attractiveness. Methods: A right smiling lateral profile photographs of a 21-year-old female subject were taken and then altered. Five final images were obtained which were printed separately and randomly distributed to four groups of evaluators (50 orthodontists, 50 dentists, 50 lay people and 50 students). A Visual Analogue Scale (VAS) was distributed to them for judgment. The obtained data were subjected to statistical analysis using ANOVA and Fischer’s test. Results: The results showed significant variation in the perception of smile based on the incisor inclination among different professionals (Wilk's Lambda, F = 2.825, P = <0.001). The original profile smile had the highest score among all professions (58% of dentists, 94% of orthodontists, 36% of students and 28% of layman). Conclusion: Orthodontists preferred inclination labially; dentists and laypeople did not appreciate excessive incisor inclination in either the lingual or the labial directions

Experimental and computational investigation on the charge storage performance of a novel Al2O3-reduced graphene oxide hybrid electrode

Abstract The advancements in electrochemical capacitors have noticed a remarkable enhancement in the performance for smart electronic device applications, which has led to the invention of novel and low-cost electroactive materials. Herein, we synthesized nanostructured Al2O3 and Al2O3-reduced graphene oxide (Al2O3-rGO) hybrid through hydrothermal and post-hydrothermal calcination processes. The synthesized materials were subject to standard characterisation processes to verify their morphological and structural details. The electrochemical performances of nanostructured Al2O3 and Al2O3- rGO hybrid were evaluated through computational and experimental analyses. Due to the superior electrical conductivity of reduced graphene oxide and the synergistic effect of both EDLC and pseudocapacitive behaviour, the Al2O3- rGO hybrid shows much improved electrochemical performance (~ 15-fold) as compared to bare Al2O3. Further, a symmetric supercapacitor device (SSD) was designed using the Al2O3- rGO hybrid electrodes, and detailed electrochemical performance was evaluated. The fabricated Al2O3- rGO hybrid-based SSD showed 98.56% capacity retention when subjected to ~ 10,000 charge–discharge cycles. Both the systems (Al2O3 and its rGO hybrid) have been analysed extensively with the help of Density Functional Theory simulation technique to provide detailed structural and electronic properties. With the introduction of reduced graphene oxide, the available electronic states near the Fermi level are greatly enhanced, imparting a significant increment in the conductivity of the hybrid system. The lower diffusion energy barrier for electrolyte ions and higher quantum capacitance for the hybrid structure compared to pristine Al2O3 justify improvement in charge storage performance for the hybrid structure, supporting our experimental findings

Rational Design of Dynamic Bimetallic NiCoSe₂/2D Ti₃C₂T<i>_x</i> MXene Hybrids for a High-Performance Flexible Supercapacitor and Hydrogen Evolution Reaction

Herein, intelligent construction of an NiCoSe2/Ti3C2Tx hybrid heterostructure with unique morphologies was performed using a hydrothermal protocol. The coexistence of the dual metal core in Ni–Co selenides and Ti3C2Tx MXene helps in realizing outclassing physicochemical properties. The two-dimensional (2D) heterostructure provides an admirably smaller Tafel slope of 86 mV/dec, indicating the faster H2 evolution rate (Pt/C: 82 mV/dec) and overpotential of 62 mV at 10 mA/cm2 (Pt/C: 52 mV/dec). Our heterostructure devices demonstrate a specific energy density of 32.05 Wh kg–1 coupled with a power density of 0.2 kW kg–1 and maintain 15.39 Wh kg–1 coupled with a power density of 0.92 kW kg–1. The experimental results underpin new profitable opportunities and scale up deployment of the bifunctional electrodes. Further, the experimental findings were supported through density functional theory (DFT) simulations in terms of a lower overpotential and higher quantum capacitance for the heterostructure NiCoSe2/MXene compared to pristine NiCoSe2. There is charge transfer from MXene Ti3C2Tx to NiCoSe2 leading to enhanced electronic states near the Fermi level responsible for enhanced catalytic activities and charge storage performance

Stability and reactivity study of bio-molecules brucine and colchicine towards electrophile and nucleophile attacks: Insight from DFT and MD simulations

© 2021 Elsevier B.V.A set of molecular descriptors have been calculated and used in order to identify the most reactive parts of bioactive molecules, brucine (BRU) and colchicine (COL). Comparison of various physico-chemical properties has been performed in order to investigate stability. Besides global and local reactive parameters, attention has been paid to the autoxidation properties and reactivity with water molecules. Molecular Dynamics (MD) simulations and docking results show that BRU and COL bound D-lactate dehydrogenase enzyme are less fluctuating and more stable than the apo protein. To reveal the autoxidation and reactivity with water molecules Density Functional Theory (DFT) simulation has been carried out for the interactions and charge transfer mechanism of water molecules on different sites of bio-molecules, BRU and COL. This may help to further understand and identify the most active parts of the bio-molecules, BRU and COL. We have presented various interaction parameters, e.g., adsorption energy, molecular distance, charge transfer and orbital interactions. The sites with higher adsorption energy and charge transfer signify better reactivity with water

A survey of perception of pain and discomfort with elastomeric separators in patients undergoing orthodontic treatment in Western Maharashtra region

Aim: The aim is to determine the perception of pain and discomfort by the patient during the placement of orthodontic separators. Materials and Methods: Elastomeric separators were placed in randomly selected 100 patients for fixed orthodontic mechanotherapy. Visual analog scale was used to register the patient's pain perception during the placement of elastomeric separators and continued subsequently on 1st, 2nd, 3rd, 4th, and 5th day. Results: The data show 41.3% of urban and 53.7% of the rural population of the patients reported pain during the placement of separators. Until the 1st day, in the urban, 53.04% of patients and in the rural population, 48.15% of patients reported pain. In the urban population, 30.43% of patients and in the rural population, 25.93% consumed analgesics. Conclusion: The pain associated peaks within 4–48 hr from separator placement, and then declines to reach its lowest level on the 5th day. Since pain of moderate intensity occurs during the treatment, analgesics and soft food are recommended

Evaluation of the awareness and knowledge of orthodontics and orthodontic treatment in patients visiting School of Dental Sciences, Karad

Aim: The aim of the study attitudes and perceptions toward dental appearance differ among populations and individuals. There is a paucity of data regarding awareness of orthodontic treatment among village population in the Indian context. Materials and Methods: After due ethical clearance, a prestructured questionnaire consisting of twenty questions was given to random 500 patients visiting the School of Dental Sciences, Karad, Maharashtra, India, in the age group of 18–25 years, who may or may not have taken orthodontic treatment. Exclusion criteria used were systemically compromised patients. The responses of the patients to the questions were recorded on a 3-point Likert scale. Simple descriptive statistics were applied to describe the study variables. The Chi-square test procedure was used to compare means for two groups. Results: Chi square tests done on the data obtained from random village population suggests that there is significant difference between the awareness of orthodotnic treatment in males and females. Conclusion: Within limits of this study, it may be concluded that people in rural areas comparatively lack awareness regarding advances and various techniques in orthodontic treatment. Although people are concerned regarding their facial appearance, lack of awareness regarding this field makes them unapproachable to an orthodontist