Genetic recombination as a generalised gradient flow

It is well known that the classical recombination equation for two parent individuals is equivalent to the law of mass action of a strongly reversible chemical reaction network, and can thus be reformulated as a generalised gradient system. Here, this is generalised to the case of an arbitrary number of parents. Furthermore, the gradient structure of the backward-time partitioning process is investigated.

New Formulation of Tertiary Amines for Thermally Stable and Cost-Effective Chemical Additive: Synthesis Procedure and Displacement Tests for High-Temperature Tertiary Recovery in Steam Applications

Summary A newly formulated chemical additive from a group of amines has been tested and applied to in-situheavy oil thermal recovery. Switchable-hydrophilicity chemical additives were successfully synthesized from N,N-dimethylcyclohexylamine in the form of homogeneous and hydrophilic solution. Fundamentally, tertiary amines comprise functional groups of hydrophilic and hydrophobic components. These unique features enable this chemical additive to wet both water and heavy oil, yielding potential interfacial tension (IFT) improvement. Furthermore, the reversible chemical reaction of this chemical additive yields both positive and negative ions. An ion pair formed due to the adsorption of cations—[C8H17NH+]—on the surface of heavy oil, whereas the anions—[HCO3−]—promoted solid-phase surface charge modification, therefore, resulting in the repulsive forces between heavy oil and the rock surface—substantially improving water-wetness and restoring an irreversible wettability alteration due to the phase change phenomenon during steam injection. In this research, two types of heavy oil acquired from a field in western Alberta encompassing the viscosity of 5,616 and 46,140 cp at 25°C was utilized in each experiment. All experiments were performed and measured at high-pressure, high-temperature (HPHT) steam conditions up to 200 psi and 200°C. We perceived that favorable IFT reduction was achieved, and irreversible wettability could be restored after combining switchable-hydrophilicity tertiary amines (SHTA) with steam as a result of the solid-phase surface charge modification to be more negatively charged. Phase distribution/residual oil in the porous media developed after steam injection was able to be favorably recovered, indicating that capillary forces could be reduced. Consequently, more than 80% of the residual oil could be recuperated post-SHTA injection, presenting favorable oil recovery performance. In addition to this promising evidence, SHTA could be potentially recovered by switching its reversible chemical reaction to be in hydrophobic form, hence, promoting this chemical additive to be both reusable and more economically effective. Comprehensive studies and analyses on interfacial properties, phase distribution in porous media, and recovery performance exhibit essential points of view in further evaluating the potential of SHTA for tertiary recovery improvement. Valuable substantiations and findings provided by our research present useful information and recommendations for fields with steam injection applications.

Термодинамический цикл Брайтона с обратимой химической реакцией

The Brighton cycle is considered, where a chemically reacting gas is used as a working substance and its molar weight and heat capacity change because of a reversible chemical reaction. The lower T_low characterizes a cycle with a constant heat supply and upper T_top temperature limits of existence, between these limits the thermal efficiency can vary from 0 to 1. Such unusual properties are manifested due to two factors: the reversibility of the chemical reaction and the special role of chemical work in the transformation heat into mechanical work.

Remediation of CO2 in Boudouard’s Reaction as an Example of Reversible Chemical Reaction

One of the fundamental elements of a scientist's work is the ability to lead observations of the phenomena that surround us and based on them making conclusions. These observations are conducted within the so-called scientific experiments. Lessons learned based on the results obtained in experiments allow researchers to better understand the essence of the phenomena occurring in the world around us. Drawing conclusions is not always easy. In order to achieve this skill, we must possess a well-established knowledge in the field of the phenomenon that interests us. The most striking example of how important skills are observation and drawing proper conclusions is the phenomenon of global climate warming. The main parameter influencing temperatures registered on Earth is the concentration of greenhouse gases in the atmosphere, and especially carbon dioxide created from combustion processes. A significant role in studies of the reduction of CO2 emissions plays chemists. To be sure that conducted by them experiments are optimally designed, it is necessary to ensure them with proper education already at the secondary school level. The main aim of this article was to conduct the study in order to explain chemical issues that create the greatest cognitive difficulties among students. The second aim of the article was to propose a chemical experiment to students that would allow them to find out more about the phenomena governing in the area of problematic issues. The proposed experiment is based on the concept of solubility equilibrium. Results of preliminary tests that have been carried out after applying this experiment on a small group of students, indicated their better understanding of the studied subject.

Detailed Balance $$=$$ Complex Balance $$+$$ Cycle Balance: A Graph-Theoretic Proof for Reaction Networks and Markov Chains

We further clarify the relation between detailed-balanced and complex-balanced equilibria of reversible chemical reaction networks. Our results hold for arbitrary kinetics and also for boundary equilibria. Detailed balance, complex balance, “formal balance,” and the new notion of “cycle balance” are all defined in terms of the underlying graph. This fact allows elementary graph-theoretic (non-algebraic) proofs of a previous result (detailed balance = complex balance + formal balance), our main result (detailed balance = complex balance + cycle balance), and a corresponding result in the setting of continuous-time Markov chains.