Nontrivial Solutions for Time Fractional Nonlinear Schrödinger-Kirchhoff Type Equations

We study the existence of solutions for time fractional Schrödinger-Kirchhoff type equation involving left and right Liouville-Weyl fractional derivatives via variational methods

ZnO quantum dots-graphene composites: Formation mechanism and enhanced photocatalytic activity for degradation of methyl orange dye

The current study demonstrates homogenous decorating of zinc oxide quantum dots (QDs) onto graphene oxide (GO) surface via simple chemical method. The AFM image exhibited that the prepared graphene was 0.8 nm thick and hence practically monolayer. Average size of the ZnO QDs was estimated by transmission electron microscopy around 3 nm. Instrumental and chemical analyses demonstrated formation of a strong bond between ZnO QDs and GO, through C-O-Zn and C-Zn bridges. The UV-visible spectra displayed that the introduction of graphene sheets to ZnO QDs resulted in higher absorption intensity of UV as well as widening of adsorption window toward visible light for ZnO-Graphene due to chemical bond between ZnO QDS and graphene surface. Results showed that adding of graphene up to 30% can improve resistance of ZnO against acids however for keeping the activity of catalyst, the recommended pH is near neutral (pH approximate to 6-7.2). In addition, the presence of graphene on the surface of the ZnO could significantly suppress the photocorrosion effect. The ZnO-Graphene hybrids indicated enhanced photocatalytic activity for degradation of methyl orange (MO) with the following order: ZnO-5% Graphene > ZnO-10% Graphene > ZnO QDs > ZnO30%-Graphene. This enhancement of photocatalytic activity may be attributed to the extended absorption of visible light, reducing of electronehole recombination rate, and adsorption of MO molecules onto the huge surface area of graphene, where they are kept at vicinity of ZnO for decomposition. (C) 2015 Elsevier B.V. All rights reserved

Multi-line AI-assisted Code Authoring

CodeCompose is an AI-assisted code authoring tool powered by large language models (LLMs) that provides inline suggestions to 10's of thousands of developers at Meta. In this paper, we present how we scaled the product from displaying single-line suggestions to multi-line suggestions. This evolution required us to overcome several unique challenges in improving the usability of these suggestions for developers. First, we discuss how multi-line suggestions can have a 'jarring' effect, as the LLM's suggestions constantly move around the developer's existing code, which would otherwise result in decreased productivity and satisfaction. Second, multi-line suggestions take significantly longer to generate; hence we present several innovative investments we made to reduce the perceived latency for users. These model-hosting optimizations sped up multi-line suggestion latency by 2.5x. Finally, we conduct experiments on 10's of thousands of engineers to understand how multi-line suggestions impact the user experience and contrast this with single-line suggestions. Our experiments reveal that (i) multi-line suggestions account for 42% of total characters accepted (despite only accounting for 16% for displayed suggestions) (ii) multi-line suggestions almost doubled the percentage of keystrokes saved for users from 9% to 17%. Multi-line CodeCompose has been rolled out to all engineers at Meta, and less than 1% of engineers have opted out of multi-line suggestions

Magnetite nanoparticles embedded on reduced graphene oxide as an anode material for high capacity and long cycle-life Li-ion battery

A facile and cost-effective method was developed for the synthesis of "magnetite/reduced graphene oxide" nanocomposite, as an anode material for lithium-ion batteries. The fabricated composite was characterized by different instrumental analyses including XRD, Raman, XPS, SEM, TEM, and FTIR, as well as various electro-chemical (i.e. battery) tests. Such broad examination revealed the structure of the prepared material and its electrochemical behavior. It was found that the fabricated composite has a number of advantages over the currently utilized electrode materials such as cost efficiency, high Li ion storage (2528 mAh/g at 0.05 A/g at 1st discharge), cycle stability of 986 mAh/g over 100 cycles at a current density of 0.1 A/g, and eventually Coulombic efficiency of about 100 %. In comparison, the reduced graphene oxide (rGO) shows inferior per-formances, such as a constant capacity of 462 mAh/g, and a slower kinetics of the ion storage. Consequently, the synthesized low-cost anode material seems to be an attractive candidate for development of the next-generation energy-storage devices, used in electrical vehicles, and portable electronic instruments

Optimal growth of sodium titanate nanoflower on TiO2 thin film for the fabrication of a novel Ti/TiO2/Na2Ti3O7 photoanode with excellent stability

This study reports the effect of the Ti source (Ti foil or TiO2 thin layer) and NaOH concentration on the growth of sodium titanate nanostructures via hydrothermal treatment to improve the photoelectrochemical (PEC) water splitting performance. An optimal condition to grow sodium titanate nanoflower composed of ultrathin nanosheets on the surface of the thin TiO2 film led to the formation of a novel nanocomposite TiO2/Na2Ti3O7 photoelectrode with great adhesion of the two phases. The Ti/TiO2/Na2Ti3O7 photoanode demonstrated a significant enhancement in photocurrent density and shifted the onset potential to a more negative value compared to the pure Ti/TiO2 and Ti/Na2Ti3O7 samples. This noticeable improvement is attributed to the suitable band alignment between the TiO2 and Na2Ti3O7 phases and their direct contact with the Ti foil, as well as the large surface area of nanoflower sodium titanate, which significantly facilitate the generation, separation, and transfer of photogenerated electrons from the active phases to the substrate. More interestingly, the prepared photoanode retained its initial photocurrent density even after 16 h. An ion-exchange method and calcination treatment were used at different temperatures to convert the Na2Ti3O7 phase in the Ti/TiO2/Na2Ti3O7 photoanode to TiO2 to investigate the role of type II heterojunction for efficient photogenerated charge carrier separation in this photoanode. It was concluded that converting Na2Ti3O7 into TiO2 in the Ti/TiO2/Na2Ti3O7 system would reduce its PEC performance due to the formation of a pure phase of TiO2 in the Ti/TiO2/TiO2 photoanode

Synthesis of “L-cysteine–graphene oxide” hybrid by new methods and elucidation of its uptake properties for Hg(II) ion

<p>This study introduces two new, simple, and scalable methods for synthesis of “cysteine–graphene oxide” hybrid, namely nucleophilic and covalent methods. Produced adsorbents could uptake 500 and 600 mg Hg²⁺/g, respectively, which are larger than capacities of most of the commercial adsorbents. By means of different instrumental techniques, chemical structures of the obtained graphene products were disclosed, and two pertinent mechanisms for their formations were suggested. Time for attaining uptake equilibrium for nucleophilic/covalent samples was 30 min/150 min, and kinetics was controlled by liquid film resistance/chemical reaction mechanisms, respectively. High selectivity and good regenerability are other key features of the prepared adsorbents.</p

Physicochemical properties of hybrid graphene-lead sulfide quantum dots prepared by supercritical ethanol

Recently, hybrid graphene–quantum dot systems have attracted increasing attention for the next-generation optoelectronic devices such as ultrafast photo-detectors and solar energy harvesting. In this paper, a novel, one-step, reproducible, and solution-processed method is introduced to prepare hybrid graphene–PbS colloids by employing supercritical ethanol. In the hybrid nanocomposite, PbS quantum dots (~3 nm) are decorated on the reduced graphene oxide (rGO) nanosheets (~1 nm thickness and less than 1 micron lengths). By employing X-ray photoelectron and Raman and infrared spectroscopy techniques, it is shown that the rGO nanosheets are bonded to PbS nanocrystals through carboxylic bonds. Passivation of {111} planes of PbS quantum dots with rGO nanosheets is demonstrated by employing density function theory. Quenching of the photoluminescence emission of PbS nanocrystals through coupling with graphene sheets is also shown. In order to illustrate that the developed preparation method does not impair the quantum efficiency of the PbS nanocrystals, the photovoltaic efficiency of solar cell device is reported and compared with oleic acid-capped PbS colloidal quantum dot solar cells. By employing the “Hall effect” measurement, it is shown that the carrier mobility is significantly increased (by two orders of magnitudes) in the presence of graphene nanosheets

Simultaneous Enhancement of Charge Separation and Hole Transportation in a W:alpha-Fe2O3/MoS2 Photoanode: A Collaborative Approach of MoS2 as a Heterojunction and W as a Metal Dopant

In this study, a facile approach has been successfully applied to synthesize a W-doped Fe2O3/MoS2 core-shell electrode with unique nanostructure modifications for photoelectrochemical performance. A two-dimensional (2D) structure of molybdenum disulfide (MoS2) and tungsten (W)-doped hematite (W:alpha-Fe2O3) overcomes the drawbacks of the a-Fe2O3 and MoS2 semiconductor through simple and facile processes to improve the photoelectrochemical (PEC) performance. The highest photocurrent density of the 0.5W:alpha-Fe2O3/MoS2 photoanode is 1.83 mA.cm(-2) at 1.23 V vs reversible hydrogen electrode (RHE) under 100 mW.cm(2) illumination, which is higher than those of 0.5W:alpha-Fe2O3 and pure alpha-Fe2O3 electrodes. The overall water splitting was evaluated by measuring the H-2 and O-2 evolution, which after 2 h of irradiation for 0.5W:alpha-Fe2O3/MoS2 was determined to be 49 and 23.8 mu mol.cm(-2), respectively. The optimized combination of the heterojunction and metal doping on pure alpha-Fe2O3 (0.5W:alpha-Fe2O3/MoS2 photoanode) showed an incident photon-to-electron conversion efficiency (IPCE) of 37% and an applied bias photon-to-current efficiency (ABPE) of 26%, which are around 5.2 and 13 times higher than those of 0.5W:alpha-Fe2O3, respectively. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications