Binding Reactions at Finite Systems

A perpetual yearn exists among computational scientists to scale-down the size of physical systems, a desire shared as well with experimentalists able to track single molecules. A question then arises whether averages observed at small systems are the same as those observed at large, or macroscopic, systems. Utilizing statistical-mechanics formulations in ensembles in which the total numbers of particles are fixed, we demonstrate that system's properties of binding reactions are not homogeneous functions. That means averages of intensive properties, such as the concentration of the bound-state, at finite-systems are different than those at large-systems. The discrepancy increases with decreasing numbers of particles, temperature, and volume. As perplexing as it may sound, despite these variations in average quantities, extracting the equilibrium constant from systems of different sizes does yield the same value. The reason is that correlations in reactants' concentrations are ought be accounted for in the expression of the equilibrium constant, being negligible at large-scale but significant at small-scale. Similar arguments pertain to the calculations of the reaction rate-constants, more specifically, the bimolecular rate of the forward reaction is related to the average of the product (and not to the product of the averages) of the reactants' concentrations. Furthermore, we derive relations aiming to predict the composition of the system only from the value of the equilibrium constant. All predictions are validated by Monte-Carlo and molecular dynamics simulations. An important significance of these findings is that the expression of the equilibrium constant at finite systems is not dictated solely by the chemical equation but requires knowledge of the elementary processes involved.

Interpreting chemistry and technology of lime binders and implementing it in the conservation field _ Interpretação da química e da tecnologia de ligantes à base de cal e sua implementação no campo da conservação

The objective of the paper is the compilation, review and dissemination of updated scientific knowledge on lime theory and technology in the field of heritage conservation.The strong evidence of the last decade’s research on the positive effect of the-not demonstrable by a chemical equation-‘key’ missing link of the maturation process is highlighted. It is demonstrated that the exceptional performance characteristics of durable lime based mortars predominately rely on the capacity for rapid, efficient and extensive carbona-tion of the air-hardening phase of limes, in particular when matured (nanoparticle wet slaked) lime putties are used; and on the chemical and mechanical stability of the strength components (principally CSHs) of the hydraulic phase of limes, which is higher in their more crystalline forms of historical lime-pozzolan mixtures than in their amorphous forms of modern cements. Hence, physicochemical adhesion and cohesion bonds both at the lime matrix and at the binder/aggregate interfaces are ensured imparting minimization of cracks and durability to lime based mortars and historic masonries.The comprehensive documentation of the former leads to optimal materials and procedures to preserve our cultural heritage. Resumo O objectivo do presente artigo é a compilação, revisão e disseminação do actual conhecimento científico sobre teoria e tecnologia da cal no campo da conservação do património. Com base na investigação da última década, são destacados os fortes indícios do efeito positivo-não demonstrável por equação química-do elo perdido ‘chave’, o processo de maturação. É demonstrado que as excepcionais características de desempenho das argamassas à base de cal mais duráveis dependem predominantemente das suas capacidades para uma rápida, eficiente e extensa carbonatação da fase de presa aérea da cal, em particular quando é usada cal em pasta com maior tempo de maturação (extinção húmida ao nível das nanopartículas); e da estabilidade química e mecânica dos com-ponentes de resistência (principalmente silicatos de cálcio hidratados (CSHs)) da fase hidráulica da cal, que é mais elevada nas for-mas mais cristalinas das misturas históricas de cal e pozolana do que nas formas amorfas dos cimentos modernos. Deste modo são asseguradas as ligações fisico-químicas por adesão e por coesão, quer na matriz de cal, quer nas interfaces ligante/agregado, conferindo minimização de fissuras e durabilidade a argamassas à base de cal e alvenarias históricas. Uma abrangente documentação destes proces-sos permitirá a obtenção de materiais e procedimentos progressivamente mais adequados à preservação do nosso património cultural. Palavras-chave Maturação; Cal em pasta; Argamassa de cal; Componentes de resistência; Estabilidade estrutural.

Domain Knowledge and Adaptive Serious Games: Exploring the Relationship of Learner Ability and Affect Adaptability

Detection and responding to a player’s affect are important for serious games. A method for this purpose was tested within Chem-o-crypt, a game that teaches chemical equation balancing. The game automatically detects boredom, flow, and frustration using the Affdex SDK from Affectiva. The sensed affective state is then used to adapt the game play in an attempt to engage the player in the game. A randomized controlled experiment incorporating a Dynamic Bayesian Network that compared results from groups with the affect-sensitive states vs those without revealed that measuring affect and adapting the game improved learning for low domain-knowledge participants.

“near wall” combustion model of spark ignition engine

This paper has illustrated a "near wall" combustion model for a spark ignition engine that was included in a two-zone thermodynamic model. The model has calculated cylinder pressure and temperature, composition, as well as heat transfer of fresh and combustion gas. The CO submodel used a simplified chemical equation to calculate the dynamics of CO during the expansion phase. Subsequently, the HC submodel is introduced, and the post-flame oxidation of un-burned hydrocarbon was affected by the reaction/diffusion phenomenon. After burning 90% of the fuel, the hydrocarbon reaction dominates at a very late stage of combustion. This modeling method can more directly describe the ?near wall? flame reaction and its contribution to the total heat release rate.

Application of the Concept of Linear Equation Systems in Balancing Chemical Reaction Equations

This study discusses the equalization of chemical reactions using a system of linear equations with the Gaussian and Gauss-Jordan elimination. The results show that there is a contradiction in the existing methods for balancing chemical reactions. This study also aims to criticize several studies that say that the equalization of the reaction coefficient can use a system of linear equations. In this paper, the chemical equations were balanced by representing the chemical equation into systems of linear equations. Particularly, the Gauss and Gauss-Jordan elimination methods were used to solve the mathematical problem with this method, it was possible to handle any chemical reaction with given reactants and products.

Text-mined dataset of inorganic materials synthesis recipes

Materials discovery has become significantly facilitated and accelerated by high-throughput ab-initio computations. This ability to rapidly design interesting novel compounds has displaced the materials innovation bottleneck to the development of synthesis routes for the desired material. As there is no a fundamental theory for materials synthesis, one might attempt a data-driven approach for predicting inorganic materials synthesis, but this is impeded by the lack of a comprehensive database containing synthesis processes. To overcome this limitation, we have generated a dataset of “codified recipes” for solid-state synthesis automatically extracted from scientific publications. The dataset consists of 19,488 synthesis entries retrieved from 53,538 solid-state synthesis paragraphs by using text mining and natural language processing approaches. Every entry contains information about target material, starting compounds, operations used and their conditions, as well as the balanced chemical equation of the synthesis reaction. The dataset is publicly available and can be used for data mining of various aspects of inorganic materials synthesis.

Stoichiometry of equations through the Inverse de Donder relation

The stoichiometry of equations was revisited in light of the Law of Conservation of Matter at an atomic, elemental level. For a balanced chemical equation following the simplest general model aA → bB, the fact that ${a \over b} = {{{n_A}} \over {{n_B}}}$, where nA is the number of moles of A consumed and nB is the number of moles of B produced in the reaction during the experiment, was used to address the de Donder relation, introduced by Theophile de Donder (1873–1957). While crediting the Belgian scientist for pointing out that “the reaction-ratio method” may be utilized for stoichiometry, the inverse de Donder relation was applied to problems in reaction stoichiometry. Several examples were used to show that the latter relation can be used to form proportions in order to rapidly solve such stoichiometry problems and to do so with fundamental chemical understanding. Educators in general chemistry were encouraged to teach the discussed method in their courses.