148 results match your criteria emitted graphene

Graphene Oxide Quantum Dots Promote Osteogenic Differentiation of Stem Cells from Human Exfoliated Deciduous Teeth via the Wnt/-Catenin Signaling Pathway.

Stem Cells Int 2021 5;2021:8876745. Epub 2021 Feb 5.

Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, China.

Graphene oxide quantum dots (GOQDs) are a carbon nanomaterial with broad potential for application in the field of nanomaterial biomedicine. Stem cells from human exfoliated deciduous teeth (SHEDs) play an important role in tissue engineering and regenerative medicine. This study investigated the effects of GOQDs on SHED osteogenic differentiation. Read More

View Article and Full-Text PDF
February 2021

Measuring prompt gamma-ray emissions from elements found in tissue during passive-beam proton therapy.

Biomed Phys Eng Express 2021 Feb 12;7(2). Epub 2021 Feb 12.

Department of Physics, RW James, University Avenue, University of Cape Town, Rondebosch 7701, Cape Town, South Africa.

Prompt gamma detection during proton radiotherapy for range verification purposes will need to operate in both active and passive treatment beam environments. This paper describes prompt gamma measurements using a high resolution 2″ × 2″ LaBrdetector for a 200 MeV clinical passive-scatter proton beam. These measurements examine the most likely discrete prompt gamma rays emitted from tissue by detecting gammas produced in water, Perspex, carbon and liquid-nitrogen targets. Read More

View Article and Full-Text PDF
February 2021

Using Geiger Dosimetry EKO-C Device to Detect Ionizing Radiation Emissions from Building Materials.

Sensors (Basel) 2021 Jan 18;21(2). Epub 2021 Jan 18.

Faculty of Production and Power Engineering, University of Agriculture in Krakow, Mickiewicza Av. 21, 31-120 Krakow, Poland.

The purpose of the article is to check and assess what radiation is emitted by particular building materials with the passage of time. The analysis was performed with the EKO-C dosimetry device from Polon-Ekolab. The scope of the work included research on sixteen selected construction materials, divided into five groups. Read More

View Article and Full-Text PDF
January 2021

Unusual Dependence of the Diamond Growth Rate on the Methane Concentration in the Hot Filament Chemical Vapor Deposition Process.

Materials (Basel) 2021 Jan 16;14(2). Epub 2021 Jan 16.

Department of Materials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea.

Although the growth rate of diamond increased with increasing methane concentration at the filament temperature of 2100 °C during a hot filament chemical vapor deposition (HFCVD), it decreased with increasing methane concentration from 1% CH -99% H to 3% CH -97% H at 1900 °C. We investigated this unusual dependence of the growth rate on the methane concentration, which might give insight into the growth mechanism of a diamond. One possibility would be that the high methane concentration increases the non-diamond phase, which is then etched faster by atomic hydrogen, resulting in a decrease in the growth rate with increasing methane concentration. Read More

View Article and Full-Text PDF
January 2021

Nanometer-Thick Crystalline Carbon Films Having a Spinel Structure Grown on ZnO Substrates: Implications for New Ceramic-Carbon Composition.

Norihiro Shimoi

ACS Omega 2020 Dec 11;5(50):32334-32340. Epub 2020 Dec 11.

Department of Electrical and Electronic Engineering, Tohoku Institute of Technology, 35-1 Yagiyama, Kasumicho, Taihaku-ku, Sendai 982-8577, Japan.

I developed a bottom-up process of crystal growth using a field emission (FE) electron beam without transfer of heat energy. In this study, highly crystalline single-walled carbon nanotubes were used as the FE electron source. Acetylene was irradiated with an electron beam of high-resolution energy emitted from the electron source. Read More

View Article and Full-Text PDF
December 2020

Abnormal Electron Emission in a Vertical Graphene/Hexagonal Boron Nitride van der Waals Heterostructure Driven by a Hot Hole-Induced Auger Process.

ACS Appl Mater Interfaces 2020 Dec 1;12(51):57505-57513. Epub 2020 Dec 1.

State Key Lab of Optoelectronic Materials and Technologies, Guangdong Province Key Lab of Display Material and Technology, Sun Yat-sen University, Guangdong 510275, People's Republic of China.

Understanding the scattering process of field injection hot carriers is important for modulating their behaviors, which is the key for improving the efficiency of charge transfer and energy conversion in hot carrier devices. In this work, a significant electron thermalization induced by Auger scattering between a field injection hot hole and a native cold electron has been observed in a vertical single layer graphene/hexagonal boron nitride/few layer graphene (Gr/hBN/FLG) device by measuring the vacuum electron emission characteristics. For the first time, it is found that vacuum electron emission can be measured under both directions of bias within the device. Read More

View Article and Full-Text PDF
December 2020

Secondary Electron Emission by Plasmon-Induced Symmetry Breaking in Highly Oriented Pyrolytic Graphite.

Phys Rev Lett 2020 Nov;125(19):196603

Institut für Theoretische Physik, Technische Universität Wien, Wiedner Hauptstraße 8-10/136, A-1040 Vienna, Austria.

Two-particle spectroscopy with correlated electron pairs is used to establish the causal link between the secondary electron spectrum, the (π+σ) plasmon peak, and the unoccupied band structure of highly oriented pyrolytic graphite. The plasmon spectrum is resolved with respect to the involved interband transitions and clearly exhibits final state effects, in particular due to the energy gap between the interlayer resonances along the ΓA direction. The corresponding final state effects can also be identified in the secondary electron spectrum. Read More

View Article and Full-Text PDF
November 2020

Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene.

Sci Rep 2020 Oct 16;10(1):17540. Epub 2020 Oct 16.

NanoScience Technology Center and Department of Physics, University of Central Florida, Orlando, FL, 32826, USA.

We present a proof of concept for a spectrally selective thermal mid-IR source based on nanopatterned graphene (NPG) with a typical mobility of CVD-grown graphene (up to 3000 [Formula: see text]), ensuring scalability to large areas. For that, we solve the electrostatic problem of a conducting hyperboloid with an elliptical wormhole in the presence of an in-plane electric field. The localized surface plasmons (LSPs) on the NPG sheet, partially hybridized with graphene phonons and surface phonons of the neighboring materials, allow for the control and tuning of the thermal emission spectrum in the wavelength regime from [Formula: see text] to 12 [Formula: see text]m by adjusting the size of and distance between the circular holes in a hexagonal or square lattice structure. Read More

View Article and Full-Text PDF
October 2020

The physisorption mechanism of SO on graphitized carbon.

Phys Chem Chem Phys 2020 Sep;22(37):21463-21473

School of Chemical and Biomedical Engineering, Nanyang Technological University, 637459, Singapore. and Singapore Membrane Technology Centre, Nanyang Environmental and Water Research Institute, Nanyang Technological University, 637141, Singapore.

Sulfur dioxide (SO2) in flue gases emitted from fossil fuel power plants dramatically reduces the CO2 capture efficiency via adsorption, which is due to the potential reaction of SO2 with basic functional groups on the adsorbent. Physisorption rather than chemisorption is preferred, because adsorbents can be more easily regenerated by either reducing the pressure or increasing the temperature. Carbon is a suitable adsorbent for SO2 capture and widely used, and therefore it is important to study SO2 adsorption onto carbon with the Monte Carlo simulation to provide microscopic details to demarcate the roles of the basal plane of the graphene layer and the functional groups in adsorption. Read More

View Article and Full-Text PDF
September 2020

Highly Conductive and Flexible Dopamine-Graphene Hybrid Electronic Textile Yarn for Sensitive and Selective NO Detection.

ACS Appl Mater Interfaces 2020 Oct 24;12(41):46629-46638. Epub 2020 Sep 24.

School of Biomedical Engineering, Korea University, Seoul 02841, South Korea.

Graphene-based electronic textile (e-textile) gas sensors have been developed for detecting hazardous NO gas. For the e-textile gas sensor, electrical conductivity is a critical factor because it directly affects its sensitivity. To obtain a highly conductive e-textile, biomolecules have been used for gluing the graphene to the textile surface, though there remain areas to improve, such as poor conductivity and flexibility. Read More

View Article and Full-Text PDF
October 2020

Recent Progress in the Development of Composite Membranes Based on Polybenzimidazole for High Temperature Proton Exchange Membrane (PEM) Fuel Cell Applications.

Polymers (Basel) 2020 Aug 19;12(9). Epub 2020 Aug 19.

Departamento de Termodinámica Aplicada (ETSII), Universitat Politècnica de València, Camino de Vera. s/n, 46022 Valencia, Spain.

The rapid increasing of the population in combination with the emergence of new energy-consuming technologies has risen worldwide total energy consumption towards unprecedent values. Furthermore, fossil fuel reserves are running out very quickly and the polluting greenhouse gases emitted during their utilization need to be reduced. In this scenario, a few alternative energy sources have been proposed and, among these, proton exchange membrane (PEM) fuel cells are promising. Read More

View Article and Full-Text PDF

Photoluminescence Response in Carbon Nanomaterials to Enzymatic Degradation.

Anal Chem 2020 10 4;92(19):12880-12890. Epub 2020 Sep 4.

Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.

Myeloperoxidase (MPO), a key enzyme released by neutrophils during inflammation, has been shown to catalyze the biodegradation of carbon nanomaterials. In this work, we perform photoluminescence studies on the MPO-catalyzed oxidation of graphene oxide (GO) and surfactant-coated pristine (6,5) single-walled carbon nanotubes (SWCNTs). The enzymatic degradation mechanism involves the introduction of defects, which promotes further degradation. Read More

View Article and Full-Text PDF
October 2020

The Effect of Periodic Spatial Perturbations on the Emission Rates of Quantum Dots near Graphene Platforms.

Materials (Basel) 2020 Aug 8;13(16). Epub 2020 Aug 8.

Electronic Imaging Center and ECE Department, New Jersey Institute of technology (NJIT), Newark, NJ 07102, USA.

The quenching of fluorescence (FL) at the vicinity of conductive surfaces and, in particular, near a 2-D graphene layer has become an important biochemical sensing tool. The quenching is attributed to fast non-radiative energy transfer between a chromophore (here, a Quantum Dot, QD) and the lossy graphene layer. Increased emission rate is also observed when the QD is coupled to a resonator. Read More

View Article and Full-Text PDF

Surface-enhanced electrochemiluminescence combined with resonance energy transfer for sensitive carcinoembryonic antigen detection in exhaled breath condensates.

Analyst 2020 Oct 6;145(20):6524-6531. Epub 2020 Aug 6.

Ministry of Education Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian Province 350116, China.

The detection of biomarkers in exhaled breath condensates (EBCs) is regarded as a promising non-invasive diagnostic approach. However, the ultralow concentration of biomarkers in EBCs is a great challenge. Herein, a sensitive dual signal amplification strategy was developed based on surface-enhanced electrochemiluminescence (SEECL) combined with resonance energy transfer (RET). Read More

View Article and Full-Text PDF
October 2020

Field Emission Properties of Polymer Graphite Tips Prepared by Membrane Electrochemical Etching.

Nanomaterials (Basel) 2020 Jul 1;10(7). Epub 2020 Jul 1.

Surface Physics and Materials Technology lab, Department of Physics, Mutah University, Al-Karak 61710, Jordan.

This paper investigates field emission behavior from the surface of a tip that was prepared from polymer graphite nanocomposites subjected to electrochemical etching. The essence of the tip preparation is to create a membrane of etchant over an electrode metal ring. The graphite rod acts here as an anode and immerses into the membrane filled with alkali etchant. Read More

View Article and Full-Text PDF

[Emission Characteristics and Risk Assessment of Volatile Organic Compounds from Typical Factories in Zhengzhou].

Huan Jing Ke Xue 2020 Jul;41(7):3056-3065

College of Resources and Environmental, Zhejiang University, Hangzhou 310058, China.

To understand the characteristics and potential hazards of volatile organic compounds (VOCs) emitted from different industrial factories in Zhengzhou, several representative factories have been selected for sample collection using canisters; the samples were subsequently analyzed by GC-MS/FID system, from which the composition and risk of VOCs are discussed in this study. It was found that OVOCs, especially ethyl acetate and isopropanol, were the most important species originating from printing factories, which accounted for more than 93.1% of total VOCs. Read More

View Article and Full-Text PDF

Emissions and exposures of graphene nanomaterials, titanium dioxide nanofibers, and nanoparticles during down-stream industrial handling.

J Expo Sci Environ Epidemiol 2020 Jun 16. Epub 2020 Jun 16.

Occupational and Environmental Medicine, Lund University, SE-22100, Lund, Sweden.

Today, engineered nanomaterials are frequently used. Nanosized titanium dioxide (TiO) has been extensively used for many years and graphene is one type of emerging nanomaterial. Occupational airborne exposures to engineered nanomaterials are important to ensure safe workplaces and to extend the information needed for complete risk assessments. Read More

View Article and Full-Text PDF

High Quality Graphene Thin Films Synthesized by Glow Discharge Method in A Chemical Vapor Deposition System Using Solid Carbon Source.

Materials (Basel) 2020 Apr 26;13(9). Epub 2020 Apr 26.

Key Laboratory of Optoelectronics Technology, Beijing University of Technology, Beijing 100124, China.

Arc discharge is traditionally used to synthesize randomly arranged graphene flakes. In this paper, we substantially modify it into a glow discharge method so that the discharge current is much more reduced. The H and/or Ar plasma etching of the graphitic electrode (used to ignite the plasma) is hence much gentler, rendering it possible to grow graphene in thin film format. Read More

View Article and Full-Text PDF

Experimental and Computational Study of Molecular Water Interactions with Condensed Nopinone Surfaces Under Atmospherically Relevant Conditions.

J Phys Chem A 2020 May 21;124(18):3652-3661. Epub 2020 Apr 21.

Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden.

Water and organics are omnipresent in the atmosphere, and their interactions influence the properties and lifetime of both aerosols and clouds. Nopinone is one of the major reaction products formed from β-pinene oxidation, a compound emitted by coniferous trees, and it has been found in both gas and particle phases in the atmosphere. Here, we investigate the interactions between water molecules and nopinone surfaces by combining environmental molecular beam (EMB) experiments and molecular dynamics (MD) simulations. Read More

View Article and Full-Text PDF

A multi-stop time-of-flight spectrometer for the measurement of positron annihilation-induced electrons in coincidence with the Doppler-shifted annihilation gamma photon.

Rev Sci Instrum 2020 Mar;91(3):033903

Department of Physics, University of Texas at Arlington, Arlington, Texas 76019, USA.

In this study, we describe an advanced multi-functional, variable-energy positron beam system capable of measuring the energies of multiple "positron-induced" electrons in coincidence with the Doppler-shifted gamma photon resulting from the annihilation of the correlated positron. The measurements were carried out using the unique characteristics of the digital time-of-flight spectrometer and the gamma spectrometer available with the advanced positron beam system. These measurements have resulted in (i) the first digital time-of-flight spectrum of positron annihilation-induced Auger electrons generated using coincident signals from a high-purity Ge detector and a micro-channel plate, (ii) a two-dimensional array of the energy of Doppler-broadened annihilation gamma and the time-of-flight of positron-annihilation induced Auger electrons/secondary electrons measured in coincidence with the annihilation gamma photon, and (iii) the time-of-flight spectra of multiple secondary electrons ejected from a bilayer graphene surface as a result of the impact and/or annihilation of positrons. Read More

View Article and Full-Text PDF

Facile in situ fabrication of biomorphic CoP-CoO/rGO/C as an efficient electrocatalyst for the oxygen reduction reaction.

Nanoscale 2020 Feb;12(7):4374-4382

School of Materials Science and Engineering, Shanghai Jiaotong University, Shanghai 200240, China.

Streptococcus thermophilus, a Gram-positive (G+) bacterium featuring a teichoic acid-rich cell wall, has been employed as both a phosphorus source and template to synthesize a biomorphic Co2P-Co3O4/rGO/C composite as an efficient electrocatalyst for the oxygen reduction reaction (ORR). Different from the conventional method for the synthesis of phosphides, bio-derivative phosphorus vapor was emitted from the inside out, which facilitated the in situ transformation of the chemically adsorbed Co precursor on the bacteria into Co2P-Co3O4 heterogeneous nanoparticles, which featured a Co2P-rich body and Co3O4-rich surface. Besides, reduced graphene oxide (rGO) was also introduced in the synthetic process to keep Co2P-Co3O4 scattered and further promote the electron transport efficiency. Read More

View Article and Full-Text PDF
February 2020

Highly selective antenna effect of graphene quantum dots (GQDs): A new fluorescent sensitizer for rare earth element terbium in aqueous media.

Talanta 2020 Mar 26;209:120504. Epub 2019 Oct 26.

College of Chemistry and Chemical Engineering, Anhui University, Hefei, 230601, China; Institute for Combustion Science and Environmental Technology, Department of Chemistry, Western Kentucky University, Bowling Green, KY, 42101, USA. Electronic address:

This study focused on the fluorescence antenna-sensitizing effect of graphene quantum dots (GQDs) in a case on the detection of terbium ions. A simple one-step chemical oxidation method was applied for the preparation of GQDs starting from the regular multilayer graphene oxide (GO) via the refluxing in a concentrated mixture of strong acids. The as-prepared GQDs were further evaluated as a fluorescent sensitizer to the terbium ion. Read More

View Article and Full-Text PDF

DNA Waves and Their Applications in Biology.

Open Access Maced J Med Sci 2019 Sep 11;7(18):3096-3100. Epub 2019 Sep 11.

Department of Dermatology, University of G. Marconi, Rome, Italy.

Aim: In this research, we show that DNA waves have many applications in biology. DNA is formed by the joining of quantum particles like electrons and charged atoms. DNA has different motions during transcription, translation, and replication, in which the charged particles move, accelerate, and emit waves. Read More

View Article and Full-Text PDF
September 2019

Triplet Excitation and Electroluminescence from a Supramolecular Monolayer Embedded in a Boron Nitride Tunnel Barrier.

Nano Lett 2020 Jan 13;20(1):278-283. Epub 2019 Dec 13.

Instituto de Energía Solar , Universidad Politécnica de Madrid , Avenida Complutense 30 , Madrid 28040 , Spain.

We show that ordered monolayers of organic molecules stabilized by hydrogen bonding on the surface of exfoliated few-layer hexagonal boron nitride (hBN) flakes may be incorporated into van der Waals heterostructures with integral few-layer graphene contacts forming a molecular/two-dimensional hybrid tunneling diode. Electrons can tunnel through the hBN/molecular barrier under an applied voltage , and we observe molecular electroluminescence from an excited singlet state with an emitted photon energy > , indicating upconversion by energies up to ∼1 eV. We show that tunneling electrons excite embedded molecules into singlet states in a two-step process via an intermediate triplet state through inelastic scattering and also observe direct emission from the triplet state. Read More

View Article and Full-Text PDF
January 2020

Graphene-Coupled Terahertz Semiconductor Lasers for Enhanced Passive Frequency Comb Operation.

Adv Sci (Weinh) 2019 Oct 23;6(20):1900460. Epub 2019 Aug 23.

State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai 200062 China.

Optical frequency combs, consisting of well-controlled equidistant frequency lines, have been widely used in precision spectroscopy and metrology. Terahertz combs have been realized in quantum cascade lasers (QCLs) by employing either an active mode-locking or phase seeding technique, or a dispersion compensator mirror. However, it remains a challenge to achieve the passive comb formation in terahertz semiconductor lasers due to the insufficient nonlinearities of conventional saturable absorbers. Read More

View Article and Full-Text PDF
October 2019

Tetraphenylethylene@Graphene Oxide with Switchable Fluorescence Triggered by Mixed Solvents for the Application of Repeated Information Encryption and Decryption.

ACS Appl Mater Interfaces 2019 Sep 10;11(38):35255-35263. Epub 2019 Sep 10.

School of Materials Science and Engineering , Tianjin University of Technology , Tianjin 300384 , P. R. China.

Aggregation-induced emission (AIE) materials present unique solid-state fluorescence. However, there remains a challenge in the switching of fluorescence quenching/emitting of AIE materials, limiting the application in information encryption. Herein, we report a composite of tetraphenylethylene@graphene oxide (TPE@GO) with switchable microstructure and fluorescence. Read More

View Article and Full-Text PDF
September 2019

Charge-Exchange-Driven Low-Energy Electron Splash Induced by Heavy Ion Impact on Condensed Matter.

J Phys Chem Lett 2019 Sep 9;10(17):4805-4811. Epub 2019 Aug 9.

Institute of Applied Physics, TU Wien, 1040 Vienna, Austria.

Low-energy electrons (LEEs) are of great relevance for ion-induced radiation damage in cells and genes. We show that charge exchange of ions leads to LEE emission upon impact on condensed matter. By using a graphene monolayer as a simple model system for condensed organic matter and utilizing slow highly charged ions (HCIs) as projectiles, we highlight the importance of charge exchange alone for LEE emission. Read More

View Article and Full-Text PDF
September 2019

High Brightness Organic Light-Emitting Diodes with Capillary-Welded Hybrid Diameter Silver Nanowire/Graphene Layers as Electrodes.

Micromachines (Basel) 2019 Aug 3;10(8). Epub 2019 Aug 3.

Key Laboratory of Advanced Display and System Applications, Ministry of Education, Shanghai University, Yanchang Road 149, Shanghai 200072, China.

The development of silver nanowire electrodes is always limited due to some disadvantages, such as roughness, oxidative properties, and other disadvantages. In this research, a capillary-welded silver nanowire/graphene composite film was used as an electrode for organic light-emitting diode (OLED) devices. As an encapsulation layer, graphene reduced the surface roughness and the oxidation probability of silver nanowires. Read More

View Article and Full-Text PDF

Fluorescent Graphitic Carbon Nitride-Based Nanozymes with Peroxidase-Like Activities for Ratiometric Biosensing.

Anal Chem 2019 08 9;91(16):10648-10656. Epub 2019 Aug 9.

Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing National Laboratory of Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials , Nanjing University , Nanjing , Jiangsu 210093 , China.

While breakthroughs in peroxidase-like nanozymes for bioanalysis have been made, most of current nanozyme biosensing systems are based on a single signal output. Such sensing systems could be easily influenced by environmental and personal factors. We envision that nanozyme sensing systems with ratiometric signal outputs would provide more reliable and robust sensing performance. Read More

View Article and Full-Text PDF

Iron-Salt Thermally Emitted Strategy to Prepare Graphene-like Carbon Nanosheets with Trapped Fe Species for an Efficient Electrocatalytic Oxygen Reduction Reaction in the All-pH Range.

ACS Appl Mater Interfaces 2019 Aug 26;11(31):27823-27832. Epub 2019 Jul 26.

National Institute for Advanced Materials, School of Materials Science and Engineering , Nankai University , Tianjin 300350 , China.

Earth-abundant, highly active, and durable electrocatalysts toward oxygen reduction reaction (ORR) in the all-pH range are highly required for practical application of electrochemical energy conversion technologies. Here, non-noble-metal graphene-like carbon nanosheets with trapped Fe species (Fe-N/GPC) are developed by an iron-salt thermally emitted strategy, which integrates the modulation of the electronic structure for boosted intrinsic activity with the engineering of hierarchical porosity for enriched active sites. The ORR electrocatalytic performance of Fe-N/GPC-800 achieves the half-wave potentials of 0. Read More

View Article and Full-Text PDF