scholarly journals The role of gold atom concentration in the formation of Cu–Au nanoparticles from the gas phase

2021 ◽  
Vol 12 ◽  
pp. 72-81
Author(s):  
Yuri Ya Gafner ◽  
Svetlana L Gafner ◽  
Darya A Ryzkova ◽  
Andrey V Nomoev
Keyword(s):  
Chemical Composition ◽  
Vapor Phase ◽  
Md Simulation ◽  
Au Nanoparticles ◽  
Bimetallic Nanoparticles ◽  
Gold Atom ◽  
Synthesis Methods ◽  
Chemical Compositions ◽  
Atom Concentration ◽  
Target Composition

The synthesis of bimetallic nanoparticles need to be controlled in order to obtain particles of a desired size, spatial structure, and chemical composition. In the synthesis of the Cu–Au nanoparticles studied here, nanoparticles can be obtained through either chemical or physical methods, each of which has its own drawbacks. Although it is very difficult to achieve the required target chemical composition of nanoparticles during chemical synthesis, their size can be stabilized quite well. In turn, physical synthesis methods mainly allow to maintain the required chemical composition; however, the size of the resulting particles varies significantly. To solve this issue, we studied the formation of Cu–Au nanoparticles with different chemical compositions from a gaseous medium using computer molecular dynamics (MD) simulation. The aim was to determine the effect of the concentration of gold atoms on the size and on the actual chemical composition of the formed bimetallic nanoparticles. The modeled region had a cubic shape with a face length of 1350 Bohr radii and contained a total of 91125 copper and gold atoms uniformly distributed in space. Thus, based on the results of the MD simulation, it was concluded that an increase in the percentage of gold atoms in the initial vapor phase led to a decrease in the size of the synthesized nanoparticles. In addition, it was found that clusters with a size of more than 400–500 atoms, regardless of the chemical composition of the initial vapor phase, basically corresponded to a given target composition.

scholarly journals The role of gold atom concentration in the processes of formation of Cu-Au nanoparticles from the gas phase

2020 ◽  
Author(s):  
Yuri Ya Gafner ◽  
Svetlana L Gafner ◽  
Darya A Ryzkova ◽  
Andrey V Nomoev
Keyword(s):  
Chemical Composition ◽  
Au Nanoparticles ◽  
Gaseous Medium ◽  
Bimetallic Nanoparticles ◽  
Gold Atom ◽  
Dynamics Simulation ◽  
Synthesis Methods ◽  
Chemical Compositions ◽  
Atom Concentration

Currently, bimetallic nanoparticles have been widely used in various fields of nanotechnology, but the main area of their application continues to be the catalysis of chemical reactions. However, it soon became clear that the catalytic activity of nanoalloys very much depends on their size, chemical composition, and shape. Therefore, the question of controlling the synthesis of bimetallic nanoparticles to obtain particles of the desired size, spatial structure, and chemical composition is very acute. In the synthesis of the Cu-Au studied by us, nanoparticles can occur either through chemical or physical methods, each of which has its own drawbacks. Though it is very difficult to achieve the required target chemical composition of nanoparticles during chemical synthesis, their size can be stabilized quite well. In turn, physical synthesis methods mainly allow you to withstand the required chemical composition, but the size of the resulting particles varies significantly. To solve this contradiction, we studied the formation of Cu-Au nanoparticles of different chemical compositions from a gaseous medium using computer Molecular Dynamics simulation to determine the effect of the concentration of gold atoms on the size and actual chemical composition of the formed bimetallic nanoparticles.

High-throughput screening of the chemical composition distribution of random styrene-butyl acrylate copolymers

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Iván García Romero ◽  
Harald Pasch
Keyword(s):  
Chemical Composition ◽  
High Throughput ◽  
Butyl Acrylate ◽  
High Throughput Screening ◽  
Size Exclusion ◽  
Chemical Compositions ◽  
Composition Distribution ◽  
Chemical Composition Distribution ◽  
Exclusion Chromatography ◽  
Liquid Chromatographic

AbstractThe development of high-throughput liquid chromatographic techniques for the analysis of styrene-butyl acrylate (SBA) copolymers is discussed. The analysis time in size-exclusion chromatography (SEC) can be reduced to about 3 min per sample when high-throughput SEC columns and high flow rates are used. In gradient HPLC, small columns with improved separation efficiencies can be applied. The time requirements can be decreased to less than 2 min per sample. Using the high-throughput HPLC technique, the chemical composition distribution of high-conversion SBA copolymers can be analyzed in a fast and efficient way. The calibration of HPLC separation is conducted by coupling the HPLC system with FTIR through the LC-transform interface. A comparison of the chemical compositions of the copolymers obtained by 1H NMR, off-line FTIR and coupled HPLCFTIR verifies the accuracy of the high-throughput copolymer analysis approach.

Relationship between Chemical Composition and the Amount of Phosphorus Adsorbed

2011 ◽  
Vol 695 ◽  
pp. 141-144
Author(s):  
Eiji Watanabe ◽  
Kaori Nishizawa ◽  
Masaki Maeda
Keyword(s):  
Chemical Composition ◽  
Chemical Compositions ◽  
Natural Materials ◽  
Adsorption Behaviors ◽  
Relationship Of

Relationship of the adsorption behaviors of phosphorus with several natural materials and artificial HAS-clay with various chemical compositions was investigated. The amounts of phosphorus adsorbed by them were closely related with the contents of aluminum in the material. It was found that the higher the aluminum contents of material, larger the amount of phosphorus were adsorbed.

Evolution of Equilibrium Composition of MnO-SiO2 and Al2O3-MnO-SiO2 Inclusions in Liquid Fe and Fe-36%Ni Alloy During Cooling

2012 ◽  
Vol 57 (2) ◽  
pp. 449-455 ◽  
Author(s):  
W. Jerzak ◽  
Z. Kalicka
Keyword(s):  
Chemical Composition ◽  
Theoretical Analysis ◽  
Thermodynamic Model ◽  
Pure Iron ◽  
Infinite Dilution ◽  
Equilibrium Composition ◽  
Inclusion Composition ◽  
Target Composition ◽  
Ni Alloy ◽  
Residual Melt

Evolution of Equilibrium Composition of MnO-SiO2and Al2O3-MnO-SiO2Inclusions in Liquid Fe and Fe-36%Ni Alloy During CoolingEvolution of chemical composition of inclusions for Fe-36%Ni melt on cooling was simulated on the basis of theoretical analysis. The equilibrium states for deoxidization reactions using manganese, silicon and aluminum were found by using the subregular solution thermodynamic model, including the interaction parameters and the activity coefficients for O, Mn, Si i Al at infinite dilution in iron and nickel. The equilibrium compositions of the inclusions when cooling the melt were computed for Fe-36%Ni for the temperatures from 1873K to 1773K. For comparison, the same analysis was made for pure iron melt. The obtained results indicate different behavior of the inclusions for those melts. For Fe-36%Ni, either MnO-SiO2inclusions or Al2O3-MnO-SiO2ones always increase substantially in MnO content on cooling. When Al2O3content goes up, the effect gets weaker. As to the pure iron melt, the inclusions behave more differently, i.e., the MnO content may go up, go down or stay constant depending on the initial inclusion composition. Despite of the fact that Al2O3-MnO-SiO2inclusions fluctuate significantly as to their compositions for Fe-36%Ni melt, it seems however, that it would be easier for this melt - in comparison to pure iron one - to forecast such a chemical target composition which would allow to achieve the desired composition of the inclusions left within the residual melt after metal cooling from 1873K to 1773 K.

scholarly journals Soil and Leaf Nutrients Drivers on the Chemical Composition of the Essential Oil of Siparuna muricata (Ruiz & Pav.) A. DC. from Ecuador

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2949
Author(s):  
Juan I. Burneo ◽  
Ángel Benítez ◽  
James Calva ◽  
Pablo Velastegui ◽  
Vladimir Morocho
Keyword(s):  
Gas Chromatography ◽  
Chemical Composition ◽  
Secondary Metabolites ◽  
Essential Oil ◽  
Chemical Elements ◽  
Climatic Conditions ◽  
Gas Chromatography Mass Spectrometry ◽  
Chemical Compositions ◽  
Leaf Nutrients ◽  
First Time

Chemical compositions of plants are affected by the initial nutrient contents in the soil and climatic conditions; thus, we analyzed for the first time the effects of soil and leaf nutrients on the compositions of the essential oils (EOs) of Siparuna muricata in four different localities in Ecuador. EOs were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS) and a gas chromatography/flame ionization detector (GC/FID). Enantiomeric distribution by GC/MS was determined, modifying the enantiomeric separation of β-pinene, limonene, δ-elemene, β-bourbonene, cis-cadina-1 (6), 4-diene and atractylone. A total of 44 compounds were identified. The most representative for L1 were guaiol, atractylone and 4-diene; for L2, cis-cadina-1(6),4-diene and myrcene; for L3, atractylone, myrcene and germacrene B; and finally, L4 germacrene B, myrcene and cis-cadina-1(6),4-diene. Correlations between soil- leaf chemical elements such as Al, Ca, Fe, Mg, Mn, N and Si in the different localities were significant with chemical composition of the essential oil of Siparuna muricata; however, correlations between soil and leaf K, P, and Na were not significant. Cluster and NMDS analysis showed high dissimilarity values of secondary metabolites between four localities related with changes in soil- leaf nutrients. Thus, the SIMPER routine revealed that not all secondary metabolites contribute equally to establishing the differences in the four localities, and the largest contributions are due to differences in guaiol, cis-cadina-1(6),4-diene, atractylone and germacrene. Our investigation showed for the first time the influences of altitude and soil- leaf chemical elements in the chemical composition of the EOs of S. muricata.

scholarly journals Relationship between the Optical Properties and Chemical Composition of Urban Aerosol Particles in Lithuania

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Julija Pauraite ◽  
Kristina Plauškaitė ◽  
Vadimas Dudoitis ◽  
Vidmantas Ulevicius
Keyword(s):  
Optical Properties ◽  
Chemical Composition ◽  
Organic Aerosol ◽  
Single Scattering ◽  
Chemical Compositions ◽  
Spectra Analysis ◽  
Average Value ◽  
Aerosol Mass ◽  
In Situ Investigation

In situ investigation results of aerosol optical properties (absorption and scattering) and chemical composition at an urban background site in Lithuania (Vilnius) are presented. Investigation was performed in May-June 2017 using an aerosol chemical speciation monitor (ACSM), a 7-wavelength Aethalometer and a 3-wavelength integrating Nephelometer. A positive matrix factorisation (PMF) was used for the organic aerosol mass spectra analysis to characterise the sources of ambient organic aerosol (OA). Five OA factors were identified: hydrocarbon-like OA (HOA), biomass-burning OA (BBOA), more and less oxygenated OA (LVOOA and SVOOA, respectively), and local hydrocarbon-like OA (LOA). The average absorption (at 470 nm) and scattering (at 450 nm) coefficients during the entire measurement campaign were 16.59 Mm−1 (standard deviation (SD) = 17.23 Mm−1) and 29.83 Mm−1 (SD = 20.45 Mm−1), respectively. Furthermore, the absorption and scattering Angström exponents (AAE and SAE, respectively) and single-scattering albedo (SSA) were calculated. The average AAE value at 470/660 nm was 0.97 (SD = 0.16) indicating traffic-related black carbon (BCtr) dominance. The average value of SAE (at 450/700 nm) was 1.93 (SD = 0.32) and could be determined by the submicron particle (PM1) dominance versus the supermicron ones (PM > 1 µm). The average value of SSA was 0.62 (SD = 0.13). Several aerosol types showed specific segregation in the SAE versus SSA plot, which underlines different optical properties due to various chemical compositions.

scholarly journals Effect of Conditions of Sol-Gel Synthesis and Post-Synthetic Treatment on Photoelectrochemical and Electro-Catalytic Properties of Titanium Oxide Nanostructures and Tio2-Au Nanocomposites

2021 ◽  
Vol 57 (4) ◽  
pp. 1-14
Author(s):  
N.I. Romanovska ◽  
◽  
P.A. Manorik ◽  
V.S. Vorobets ◽  
G.Ya. Kolbasov ◽  
...  
Keyword(s):  
Visible Light ◽  
Au Nanoparticles ◽  
Sol Gel ◽  
Au Nanoparticle ◽  
Chemical Compositions ◽  
High Catalytic Activity ◽  
Electron Microscopies ◽  
Treatment Conditions ◽  
Carboxylate Groups ◽  
Tio2 Nanostructures

Carbon-doped mesoporous TiO2 nanostructures and TiO2-Au nanocomposites with stabilized Au nanoparticles have been synthesized by the sol-gel template method and characterized by X-ray diffraction, scanning and transmission electron microscopies, Fourier-transform infrared spectroscopy, N2 adsorption/desorption, ultraviolet-visible spectroscopy, and photoelectrochemical current spectroscopy. The synthesis hydrothermal treatment conditions affected the particle size, electronic structure, morphology, phase, and chemical compositions, as well as the texture of the synthesized materials. The TiO2 and TiO2-Au based electrodes were light-sensitive in a wavelength range of 250–412 nm and were distinguished by a high catalytic activity during oxygen electroreduction. The presence of -ol and carboxylate groups in the amorphous phase is the main factor affecting the photosensitivity of TiO2 nanostructures to visible light and an increase in their photoactivity during the decomposition of methylene blue upon irradiation with ultraviolet and visible light relative to pure anatase. The higher photosensitivity and photoactivity of TiO2-Au nanocomposites compared with those of the corresponding starting TiO2 is due to the synergistic effect of Au nanoparticles and interstitial Ti-O-C groups, which depends on the Au nanoparticle content of the composite and on the mesopore size.

scholarly journals Low Density Multi-principal Element Alloy from Al-Mg-Ca-Si-B System

2019 ◽  
Vol 70 (7) ◽  
pp. 2315-2320
Author(s):  
Victor Geanta ◽  
Robert Ciocoiu ◽  
Ionelia Voiculescu
Keyword(s):  
Chemical Composition ◽  
Chemical Element ◽  
Mechanical Characteristics ◽  
Cast Alloy ◽  
Complex Oxides ◽  
Scientific Paper ◽  
Chemical Compositions ◽  
Low Density ◽  
Principal Element ◽  
Research Stage

The scientific paper presents a numerical modeling of the chemical composition for the optimization of the multicomponent light alloys in the Al-Mg-Ca-Si-B system. The effects of the proportion of each chemical element on the main characteristics of the alloy based on the mixture rule and the correlation between the melting temperature and the modulus of elasticity were analyzed numerically. The model results has reveals that even other factors must be taken into account, i.e. the mechanical characteristics which varied significantly with changing of chemical compositions. A compromise was set, by slightly increasing the density to acquire better mechanical characteristics. The selected chemical composition was then used to obtain the new low density alloy. In current research stage we conclude that the as cast alloy comprises an inhomogeneous solid solution and complex oxides. Further studies are ongoing on the experimental alloy in various states (homogenization annealed and processed by plastic deformation).

scholarly journals Comparison of chemical compositions of essential oils isolated by hydrodistillation from wild thyme (Thymus serpyllum L.) with use of Deryng and Clevenger apparatus

2014 ◽  
Vol 60 (2) ◽  
pp. 7-17 ◽  
Author(s):  
Aneta Wesołowska ◽  
Monika Grzeszczuk ◽  
Dorota Jadczak
Keyword(s):  
Chemical Composition ◽  
Essential Oil ◽  
Essential Oils ◽  
Methyl Ether ◽  
The Other ◽  
Chemical Compositions ◽  
Distillation Apparatus ◽  
Ms Analysis ◽  
Wild Thyme ◽  
Thymus Serpyllum

Abstract The aim of the studies conducted in 2012-2013 was to compare the chemical composition of essential oils isolated from wild thyme (Thymus serpyllum L.) by hydrodistillation in Deryng and Clevenger apparatus. GC-MS analysis of the isolated oils revealed that carvacrol (42.81-45.24%), γ-terpinene (7.68-9.04%), β-caryophyllene (5.28-9.10%), β-bisabolene (5.76-6.91%) and carvacrol methyl ether (4.92-6.09%) were the major components of all the samples. On the basis of the obtained data it was proved that the type of distillation apparatus had no significant effect on the content of the main essential oil constituents of wild thyme. However, based on the means for both years of the study it was proved that hydrodistillation in Deryng apparatus was more effective for carvacrol concentration, while in Clevenger apparatus - for y-terpinene and carvacrol methyl ether concentration. The type of distillation apparatus had no significant effect on the content of the other essential oil constituents.

Sign in / Sign up

Export Citation Format

Share Document