scholarly journals Chemical bath synthesis of metal chalcogenide films. Part 42. Experimental verification of the deposition regions of PbSe by sodium selenosulfate and selenourea in the presence of various ligands

2019 ◽  
Vol 60 (10) ◽  
pp. 88-98
Author(s):  
Larisa N. Maskaeva ◽  
◽  
Victoria M. Yurk ◽  
Anastasia V. Belceva ◽  
Ivan V. Zarubin ◽  
...  
Keyword(s):  
Metal Salt ◽  
Three Dimensional ◽  
Reaction System ◽  
Iodine Content ◽  
Solution Concentration ◽  
Synthesis Process ◽  
Initial Concentration ◽  
Reaction Systems ◽  
Sodium Selenosulfate ◽  
System 1

Calculation of ionic equilibria in the reaction system for synthesis of PbSe thin films was carried out. Three reaction systems containing the following combinations of reagents were considered: sodium citrate with liquid ammonia and sodium selenosulfate (system 1) or selenourea (system 2) used as chalcogenizer, ethilendiamine, sodium acetate and selenourea (system 3).The main lead complex compoundsprevented the fast PbSe formation in system 1 and 2 in region of pH of intensive selenosulfate and selenourea decomposition were hydroxo-citrate complexes. In the system 3 complexes with ethilendiamine and acetate-ions played the most significant role. For evaluating the deposition conditions of the main and impurity phases (metal hydroxides and cyanamides) by thermodynamic calculations taking into account the sizes of critical nucleis, the boundary conditions and regions of formation of PbSe, Pb(OH)2, PbCN2 in the studied reaction systems were found. The calculation results are presented in the form of three-dimensional dependencies in the coordinates “indicator of the initial concentration of the metal salt – pH of the solution – ligand concentration” and “indicator of the initial concentration of the metal salt – pH of the solution – concentration of the chalcogenizer”. Based on the calculations and preliminary experiments, the compositions of the discussed reaction mixtures were formed for the chemical bath deposition of PbSe films, which, in addition to the main components, included a dopant in the form of ammonium iodide. In the synthesis process at a temperature of 353 K (system 1 and 2) for 60 minutes and 308 K for 90 minutes (system 3), using all the studied reaction systems on glass substrates, homogeneous PbSe layers with a thickness of ~500 to ~700 nm were obtained. The ratio between the main elements of Pb and Se in the film varies between 0.98-1.32, and the iodine content is 7-11 at.% depending on the composition of the reaction bath.

SYNTHESIS AND CHARACTERIZATION OF 3D CARBON NANOTUBES

MRS Advances ◽  
2018 ◽  
Vol 3 (1-2) ◽  
pp. 103-108
Author(s):  
Oxana V. Kharissova ◽  
Beatriz Ortega Garcia ◽  
Patsy Y. Arquieta Guillén ◽  
Hugo V. Galindo Cuevas ◽  
Romeo Selvas Aguilar
Keyword(s):  
Carbon Nanotubes ◽  
3D Structure ◽  
Three Dimensional ◽  
Multiwall Carbon Nanotubes ◽  
Solution Concentration ◽  
Synthesis Process ◽  
Synthesis Time ◽  
Research Areas ◽  
Functionalization Of Carbon Nanotubes ◽  
Nanoparticles Of Silver

ABSTRACTA nanomaterial that attracts the attention in a variety of research areas is multiwall carbon nanotubes (MWCNTs), due to their good mechanical proprieties, and high electrical and thermal conductivity. For this reason, the preparation of three-dimensional (3D) structures from them draws interest because it opens new horizons to produce materials with novel properties and useful applications. In this investigation the synthesis of 3D nanotube carbon (nanoforest type) functionalized with nanoparticles of silver, aluminum, and iron was studied. A 3D structure was produced in the form of aligned microchannels. The functionalization of carbon nanotubes with nanoparticles of silver, aluminum or iron during the synthesis process of carbon nanotubes, was carried out through spray-pyrolysis with different synthesis time and solution concentration. The results were characterized through microscopy SEM, TEM and Raman’s spectroscopy.

Characterization of a monolayer graphitic structure

1994 ◽  
Vol 52 ◽  
pp. 760-761
Author(s):  
X. Lin ◽  
X. K. Wang ◽  
V. P. Dravid ◽  
J. B. Ketterson ◽  
R. P. H. Chang
Keyword(s):  
Three Dimensional ◽  
Single Layer ◽  
Synthesis Process ◽  
Graphitic Structure ◽  
Positive Gaussian Curvature ◽  
Graphitic Sheet ◽  
Structural And Electronic Properties ◽  
New Material ◽  
Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

scholarly journals SiCaSMA: An Alternative Stochastic Description via Concatenation of Markov Processes for a Class of Catalytic Systems

Mathematics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1074
Author(s):  
Vincent Wagner ◽  
Nicole Erika Radde
Keyword(s):  
Reaction System ◽  
Stochastic Simulation Algorithm ◽  
Test Bed ◽  
Biochemical Reaction Networks ◽  
Full System ◽  
Catalytic Systems ◽  
Reaction Systems ◽  
Sample Paths ◽  
Alternative Description ◽  
Linear Differential

The Chemical Master Equation is a standard approach to model biochemical reaction networks. It consists of a system of linear differential equations, in which each state corresponds to a possible configuration of the reaction system, and the solution describes a time-dependent probability distribution over all configurations. The Stochastic Simulation Algorithm (SSA) is a method to simulate sample paths from this stochastic process. Both approaches are only applicable for small systems, characterized by few reactions and small numbers of molecules. For larger systems, the CME is computationally intractable due to a large number of possible configurations, and the SSA suffers from large reaction propensities. In our study, we focus on catalytic reaction systems, in which substrates are converted by catalytic molecules. We present an alternative description of these systems, called SiCaSMA, in which the full system is subdivided into smaller subsystems with one catalyst molecule each. These single catalyst subsystems can be analyzed individually, and their solutions are concatenated to give the solution of the full system. We show the validity of our approach by applying it to two test-bed reaction systems, a reversible switch of a molecule and methyltransferase-mediated DNA methylation.

scholarly journals Synthesis of luminescent thorium-based metal–organic frameworks with 1,2,4,5-tetrakis(4-carboxyphenyl)benzene

RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17431-17436
Author(s):  
Ting Yu ◽  
Zheng-hua Qian ◽  
Lin Li ◽  
Xiao-ling Wu ◽  
Hui He ◽  
...  
Keyword(s):  
Metal Salt ◽  
Metal Organic Frameworks ◽  
Reaction System ◽  
Similar Reaction ◽  
Metal Organic

Three new thorium-based MOFs based on 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (H4TCPB) were obtained under a similar reaction system (metal salt, ligand, solvent, and acid are the same).

A comparative study and combined application of RSM and ANN in adsorptive removal of diuron using biomass ashes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sunil K. Deokar ◽  
Nachiket A. Gokhale ◽  
Sachin A. Mandavgane
Keyword(s):  
Three Dimensional ◽  
Current Approach ◽  
Coefficient Of Determination ◽  
Ann Model ◽  
Operational Parameters ◽  
Initial Concentration ◽  
Combined Application ◽  
Artificial Neural Network Ann ◽  
Relationship Of ◽  
Biomass Ashes

Abstract Biomass ashes like rice husk ash (RHA), bagasse fly ash (BFA), were used for aqueous phase removal of a pesticide, diuron. Response surface methodology (RSM) and artificial neural network (ANN) were successfully applied to estimate and optimize the conditions for the maximum diuron adsorption using biomass ashes. The effect of operational parameters such as initial concentration (10–30 mg/L); contact time (0.93–16.07 h) and adsorbent dosage (20–308 mg) on adsorption were studied using central composite design (CCD) matrix. Same design was also employed to gain a training set for ANN. The maximum diuron removal of 88.95 and 99.78% was obtained at initial concentration of 15 mg/L, time of 12 h, RHA dosage of 250 mg and at initial concentration of 14 mg/L, time of 13 h, BFA dosage of 60 mg respectively. Estimation of coefficient of determination (R 2) and mean errors obtained for ANN and RSM (R 2 RHA = 0.976, R 2 BFA = 0.943) proved ANN (R 2 RHA = 0.997, R 2 BFA = 0.982) fits better. By employing RSM coupled with ANN model, the qualitative and quantitative activity relationship of experimental data was visualized in three dimensional spaces. The current approach will be instrumental in providing quick preliminary estimations in process and product development.

Fenton-like reaction system with an analyte-activated catfish effect for enhanced colorimetric and photothermal dopamine bioassay

The Analyst ◽  
2020 ◽  
Author(s):  
Zhengrong Niu ◽  
Hong-Hong Rao ◽  
Xin Xue ◽  
Mingyue Luo ◽  
Xiuhui Liu ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Advanced Oxidation Processes ◽  
Reaction System ◽  
Reactive Oxygen ◽  
Advanced Oxidation ◽  
Oxygen Species ◽  
Reaction Systems ◽  
Oxidation Processes

Fenton-like reaction systems have been proven to be more efficient as the powerful promoters in advanced oxidation processes (AOPs) due to their resultantly generated reactive oxygen species (ROS) such as...

scholarly journals Degradation of methylene blue by natural manganese oxides: kinetics and transformation products

2019 ◽  
Vol 6 (7) ◽  
pp. 190351 ◽  
Author(s):  
Shuangxi Zhou ◽  
Zhiling Du ◽  
Xiuwen Li ◽  
Yunhai Zhang ◽  
Yide He ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Manganese Oxides ◽  
Ph Value ◽  
Low Cost ◽  
Reaction System ◽  
Transformation Products ◽  
Low Ph ◽  
Initial Concentration ◽  
Environmental Material ◽  
High Redox Potential

In this study, natural manganese oxides (MnO x ), an environmental material with high redox potential, were used as a promising low-cost oxidant to degrade the widely used dyestuff methylene blue (MB) in aqueous solution. Although the surface area of MnO x was only 7.17 m 2 g −1 , it performed well in the degradation of MB with a removal percentage of 85.6% at pH 4. It was found that MB was chemically degraded in a low-pH reaction system and the degradation efficiency correlated negatively with the pH value (4–8) and initial concentration of MB (10–50 mg l −1 ), but positively with the dosage of MnO x (1–5 g l −1 ). The degradation of MB fitted well with the second-order kinetics. Mathematical models were also built for the correlation of the kinetic constants with the pH value, the initial concentration of MB and the dosage of MnO x . Furthermore, several transformation products of MB were identified with HPLC-MS, which was linked with the bond energy theory to reveal that the degradation was initiated with demethylation.

Networks of Reaction Systems

2020 ◽  
Vol 31 (01) ◽  
pp. 53-71 ◽  
Author(s):  
Paolo Bottoni ◽  
Anna Labella ◽  
Grzegorz Rozenberg
Keyword(s):  
Reaction System ◽  
Reaction Systems

In this paper, we study the behavior (processes) of reaction systems where the context is not arbitrary, but it has its own structure. In particular, we consider a model where the context for a reaction system originates from a network of reaction systems. Such a network is formalized as a graph with reaction systems residing at its nodes, where each reaction system contributes to defining the context of all its neighbors. This paper provides a framework for investigating the behavior of reaction systems receiving contexts from networks of reaction systems, provides a characterisation of their state sequences, and considers different topologies of context networks.

scholarly journals Coarse-graining via EDP-convergence for linear fast-slow reaction systems

2020 ◽  
Vol 30 (09) ◽  
pp. 1765-1807 ◽  
Author(s):  
Alexander Mielke ◽  
Artur Stephan
Keyword(s):  
Detailed Balance ◽  
Reaction System ◽  
Gradient Flow ◽  
Coarse Graining ◽  
Reaction Rates ◽  
Coarse Grained ◽  
Gradient Structure ◽  
Reaction Systems ◽  
Fast Reactions ◽  
Finite State

We consider linear reaction systems with slow and fast reactions, which can be interpreted as master equations or Kolmogorov forward equations for Markov processes on a finite state space. We investigate their limit behavior if the fast reaction rates tend to infinity, which leads to a coarse-grained model where the fast reactions create microscopically equilibrated clusters, while the exchange mass between the clusters occurs on the slow time scale. Assuming detailed balance the reaction system can be written as a gradient flow with respect to the relative entropy. Focusing on the physically relevant cosh-type gradient structure we show how an effective limit gradient structure can be rigorously derived and that the coarse-grained equation again has a cosh-type gradient structure. We obtain the strongest version of convergence in the sense of the Energy-Dissipation Principle (EDP), namely EDP-convergence with tilting.

Buffer capacity in multiple chemical reaction systems involving solid phases

2006 ◽  
Vol 84 (8) ◽  
pp. 1036-1044 ◽  
Author(s):  
Ilie Fishtik ◽  
Igor Povar
Keyword(s):  
Chemical Reaction ◽  
Buffer Capacity ◽  
Reaction System ◽  
Chemical Species ◽  
Abundant Species ◽  
Stoichiometric Coefficient ◽  
Reaction Systems ◽  
Chemical Reaction Systems ◽  
Chemical Reaction System ◽  
Multiple Chemical

The buffer capacity of a chemical species in a multiple chemical reaction system is discussed in terms of a special class of stoichiometrically unique reactions referred to as response reactions (RERs). More specifically, it is shown that the buffer capacity may be partitioned into a sum of contributions associated with RERs. This finding provides a deeper understanding of the factors that determine the buffer capacity. In particular, the main contributions to the buffer capacity come from the RERs involving the most abundant species. Concomitantly, the RERs approach provides a simple stoichiometric algorithm for the derivation and analysis of the buffer capacity that may be easily implemented into a computer software.Key words: buffer capacity, response reaction, heterogeneous system, stoichiometric coefficient.

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