Two-step pyrolysis of ZIF-8 functionalized with ammonium ferric citrate for efficient oxygen reduction reaction

Zeolitic imidazolate frameworks（ZIFs） are widely employed in catalyst synthesis as parental materials for electrochemical energy storage and conversion. Herein, we have demonstrated a facile synthesis of highly efficient catalyst for oxygen reduction reaction in both alkaline and acidic medium, which is derived from ZIF-8 functionalized with ammonium ferric citrate via two-step pyrolysis in Ar and NHatmosphere.The results reveal that the catalytic activity improvement after NH3 pyrolysis benefits from mesoporedominated morphology and high utilization of Fe-containing active sites. The optimum catalyst shows excellent performance in zinc-air battery and polymer electrolyte membrane fuel cell tests.

Estimation on Global Reaction Heat for the Aromatization Process of Liquefied Petroleum Gas

The reaction heat effect analysis for the aromatization process of Liquefied Petroleum Gas (LPG) was completed in this paper. In order to characterize this complex reaction system, one set of independent reactions was determined by means of atomic coefficient matrix method. Based on reaction thermodynamic and stoichiometric knowledge, the heat effect, Gibbs free energy change and equilibrium constant for each independent reaction was calculated for the specified conditions. Under these conditions, based on the initial and final composition data from LPG aromatization experiments, the actual extent of reaction for each independent reaction was determined. Furthermore, the global reaction heat and adiabatic temperature rise of LPG aromatization reaction system could be estimated. This work would provide a theoretical guidance for the design and scale-up of reactor for LPG aromatization process, as well as for the selection of proper operating conditions.

Misconceptions in global reactions and formula writing

The frequently used concept of "global reaction" is discussed and the reason for the confusion behind explained. The misconception is cleared by formula writing based on the donor–acceptor(donac) reaction concept and by applying the Grand Rule of Formula Writing that is based on it.

Global existence and blow up of solutions for two classes of reaction diffusion systems with two nonlinear source terms in bounded domain

In this paper we deal with the initial boundary value problem for two classes of reaction diffusion systems with two source terms in bounded domain. Under some assumptions on the exponents and the initial data, applying the comparison principle, the maximum prin- ciple and the supersolution-subsolution method, we prove the global existence and blow up of solutions. We also establish some upper blow up rates.

A NOTE ON THE GLOBAL SOLUTIONS OF A SEMILINEAR REACTION DIFFUSION SYSTEM

This note studies the global solutions of a semilineear reaction diffusion system which comes from an exothermic themical reaction.This is a complement of paper[1]and gives a positive answer to the question mentioned by paper[2].

Global Bounded Solutions for Reaction-diffusion Systems with a Full Matrix of Diffusion Coefficients and a Balance Law

This paper deals with an initial boundary value problem for the strongly coupledreaction-diffusion systems with a full matrix of diffusion coefficients. The global existence ofsolutions is proved by using the techniques based on invariant regions, Lyapunov functionalmethods, and local Lp prior estimates independent of time.

Global attractors associated with general partly dissipative reaction-diffusion systems in unbounded domains

The asymptotic behaviour of solutions for general partly dissipative reaction-diffusion systems in Rn is studied. The asymptotic compactness of the solutions and then the existence of the global attractor are proved in L2(Rn )× L2(Rn ) .

Forecast of the Luminescent Phenomena of Silicon Rich Oxide Films off Stoichiometry by Means of the Global Reaction Model

The Global Reaction Model describes a set of chemical reactions that can potentially occur during the process of obtaining silicon rich oxide (SRO) films, regardless of the technique used to grow such films which are an outside stoichiometry material. Particularly, chemical reactions that occur during the process of growing of SRO films by LPCVD technique are highlighted in this model. We suggest and evaluate either some types of molecules or resulting nanostructures and we predict theoretically, by applying the density functional theory, the contribution that they may have to the phenomenon of luminescence which is measured in SRO films. Also, we have calculated the opto-electronic properties of SRO films. The suggested model provides enough information required to identify the molecular structures resulting from the presence of defects in SRO films and also those corresponding to charged structures. It is also possible to detect the molecular structures which are modified due to the effect of heat treatment, and identify the presence of different oxidation states inclusive the formation of siloxanes.

The Role of Enthalpy of Reaction in the Process of Global Warming: What Can We Learn from Basic Thermodynamics*

An increase of carbon dioxide content accompanied by an increase of the temperature is observed in the atmosphere during the last 200 years. This behaviour can be explained by examination of correlations between tree generally accepted data sets of the recent past, world population, carbon dioxide content in the atmosphere, and rise of global temperature as function of time. No return to climate situations from hundred thousand of years before present is necessary. The world climate is a dynamic equilibrium between all energy generating processes on earth, especially sun energy, and the radiation of energy into space. Since approx. 200 years the dynamic equilibrium is changed additionally by means of fossil energy carriers, whose depots were put on in passed geological epochs, a climatic disturbance was produced. It is shown that the consumption of energy per year by the mankind can warm up the atmosphere by about one degree. This quantity cannot be neglected in climatic calculations;therefore it is the cause of mankind made warming of the atmosphere. The qualitative analyses presented here have shown that the use of so-called renewable energy sources does not necessarily lead to the avoidance of global warming. It can be expected that some techniques will have no or even small effect. Especially the model calculations to the operation of wind turbines and its influence on the temperature of the atmosphere show that it is difficult to estimate their influence and cannot be foreknown.

GLOBAL EXISTENCE OF SOLUTIONS FOR A STRONGLY COUPLED REACTION-DIFFUSION SYSTEM

This paper is concerned with an Initial Boundary Value Problem (IBVP) for a strongly coupled semilinear reaction-diffusion system. By using the upper and lower solutions method and Leray-Schauder fixed point theorem and so on, the authors prove the global existence and uniqueness of a. smooth. solution for this IBVP under some appropriate conditions.

Preparing low-oxygen Ti-6Al-4V alloy powder through direct reduction of oxides and its synergistic reaction mechanism

Ti-6Al-4V alloy powder was prepared through a two-step reduction of a mixture of TiO_(2),V_(2)O_(5) and Al_(2)O_(3) in this study.The oxide mixture was first reduced by Mg in MgCl_(2) at 750℃ in argon,where oxygen was reduced to 2.47 wt%from 40.02 wt%.The oxygen content in the final powder was eventually reduced to an extremely low level(0.055 wt%)using calcium at 900℃ in argon,and the final powder had the composition of 90.12 wt%Ti,5.57 wt%Al,and 3.87 wt%V,which meets the standard specification of Ti-6Al-4V(ASTM F1108-09).Between the two reductions,a heat treatment step was designed to help controlling the specific surface area and particle size.The effect of the heat treatment temperature on the morphology,and composition uniformity of the powder was investigated in detail.Heat treatment above 1300℃ attributed to a dense powder with a controlled specific surface area.Thermodynamic modeling and experimental results indicated that onlyα-Ti enriched with Al andβ-Ti enriched with V exist in the final powder,and other possible phases including Al-Mg and Al-V were excluded.This study also offers a triple-step thermochemical process for producing high-purity Ti-based alloy powder.

The Nucleon-Actinide Global Optical Model Potential Below 300 MeV

A set of new global phenomenological optical model potential parameters has been obtained in the mass range of target nuclei 220≤A≤260 with incident energies below 300 MeV, by simultaneously fitting the experimental data of 232Th and 23Su, and these potential parameters are analyzed and used to calculate the reaction cross sections, energy spectra and double differ- ential cross sections for p＋232Th reaction. Comparison of calculated results using these potential parameters with available experimental data shows that the present form of global optical model potential could reproduce experimental data for both the neutron and the proton.

Global Asymptotic Stability and Hopf Bifurcation in a Homogeneous Diffusive Predator-Prey System with Holling Type II Functional Response

In this paper, we considered a homogeneous reaction-diffusion predator-prey system with Holling type II functional response subject to Neumann boundary conditions. Some new sufficient conditions were analytically established to ensure that this system has globally asymptotically stable equilibria and Hopf bifurcation surrounding interior equilibrium. In the analysis of Hopf bifurcation, based on the phenomenon of Turing instability and well-done conditions, the system undergoes a Hopf bifurcation and an example incorporating with numerical simulations to support the existence of Hopf bifurcation is presented. We also derived a useful algorithm for determining direction of Hopf bifurcation and stability of bifurcating periodic solutions correspond to j ≠0 and j = 0, respectively. Finally, all these theoretical results are expected to be useful in the future study of dynamical complexity of ecological environment.

Adsorption of CO₂and H₂on Cu and Zn Micro-Cluster Surfaces Studied by Quantum Chemistry and Theory of Absolute Reaction Rates

Statistical mechanics and semi-empirical molecular orbital theory (PM6) are used to calculate the surface coverage of CO2 and H2 molecular species chemically adsorbed on the surface of Cu and Zn micro clusters. The calculation shows that CO2 is adsorbed well both on the surface of Cu and Zn micro clusters. Although H2 is adsorbed well on the surface of Zn micro clusters, H2 absorption on the surface of Cu micro clusters is much more limited in the pressure range of 20 - 100 atm and temperature range of 200 - 1000 K. Reaction rates are also estimated for some chemical adsorption process of H2 gas using theory of absolute reaction rates. It is found that the values of the reaction rate calculated in the present paper agree reasonably well with the experimental values.

Critical Fujita Exponents for Localized Reaction Diffusion Systems

In this paper, we prove the existence of cirtical Fujita exponents for a class of localized reaction diffusion systems.

Gamma Cascade Transition of ⁵¹V(n_th, <i>g </i>)⁵²V Reaction

The thermal neutron capture gamma radiations for 51V(n, g)52V reaction have been studied at Dalat Nuclear Research Reactor (DNRR). The gamma two-step cascade transition was measured by event-event coincidence spectrometer. The added-neutron binding energy in 52V was measured as 7.31 MeV. Energy and the intensity transition of cascades were consistent with prediction of single particle model. Furthermore, the spin and the parity of levels were confined.

Heat Propagation of Eyring-Prandtl Double Reaction and Pressure Driven Hydromagnetic Viscous Heating Fluid in a Device

The effect toxic industrial discharge on the environment and ecosystem cannot be overlooked. This is owing to a partial combustion of hydrocarbon arising from industrial activities and human endeavours. As such, this investigation focuses on the pressure driven flow and heat propagation of combustible Prandtl-Eyring viscous heating fluid in a horizontal device. The combustion-reaction of the viscoplastic material is considered to be inspired by two-step exothermic reaction. With negligible reactant consumption, the flowing fluid is influenced by a chemical kinetic, activation energy and electromagnetic force. An invariant transformation of the partial derivative model to an ordinary derivative model is obtained through an applied dimensionless variable. The solutions to the unsteady thermal fluid flow model are obtained via a semi-implicit difference scheme, and the outputs of the solution are displayed in plots and tables. As revealed, an enhanced heat propagation is obtained that in turn encourages the combustion process of the system. Also, increasing material dilatant simulated fluid molecular bond and viscosity. Therefore, the outcomes of this study are treasured to the thermal and chemical engineering, and the environmental management.

GLOBAL EXISTENCE AND ASYMPTOTIC BEHAVIOR OF SOLUTIONS FOR SOME COUPLED SYSTEMS VIA A LYAPUNOV FUNCTIONAL

The purpose of this work is to study the global existence and asymptotic behavior of solutions to a coupled reaction-diffusion system describing epidemiological or chemical situations. Our analytical proofs are based on the Lyapunov functional methods.

Wave equations and reaction-diffusion equations with several nonlinear source terms

The initial boundary value problem of wave equations and reaction-diffusion equations with several nonlinear source terms in a bounded domain is studied by potential well method. The invarianee of some sets under the flow of these problems and the vacuum isolation of solutions are obtained by introducing a family of potential wells. Then the threshold result of global existence and nonexistence of solutions are given. Finally, the problem with critical initial conditions are discussed.

UPPER SEMICONTINUITY OF ATTRACTORS FORTHE REACTION DIFFUSION EQUATION

This paper deals with the reaction diffusion equation in domain, Omega = R or Omega = (-L, L) with L < infinity. Let A(L) and A be the global attractor of this equation corresponding to Omega = (-L,L) and Omega = R, respectively. It is showed that the global attractor A is upper semicontinuity at 0 with respect to the sets {A(L)} in some sense.