Le Chatelier's Principle Research Articles

Protein Signaling Networks from Single Cell Fluctuations and Information Theory Profiling

Protein signaling networks among cells play critical roles in a host of pathophysiological processes, from inflammation to tumorigenesis. We report on an approach that integrates microfluidic cell handling, in situ protein secretion profiling, and information theory to determine an extracellular protein-signaling network and the role of perturbations. We assayed 12 proteins secreted from human macrophages that were subjected to lipopolysaccharide challenge, which emulates the macrophage-based innate immune responses against Gram-negative bacteria. We characterize the fluctuations in protein secretion of single cells, and of small cell colonies (n = 2, 3,···), as a function of colony size. Measuring the fluctuations permits a validation of the conditions required for the application of a quantitative version of the Le Chatelier's principle, as derived using information theory. This principle provides a quantitative prediction of the role of perturbations and allows a characterization of a protein-protein interaction network.

Electrical current mediated interconversion between graphene oxide to reduced grapene oxide

In this work, we demonstrate that graphene oxide (GO) can be reversibly converted to reduced-graphene-oxide (rGO) through the use of electric current. Strong electric field could cause ionization of water molecules in air to generate H+ ions at cathode, causing GO to be reduced. When the bias is reversed, the same electrode becomes positive and OH− ions are produced. According to Le Chatelier Principle, it then favors the reverse reaction, converting rGO back to GO, GO+2H++2e−=>rGO+H2O. X-ray spectroscopy and Raman spectroscopy were carried to verify the conversion reversibility in the reversed process.

Size and sequence and the volume change of protein folding.

The application of hydrostatic pressure generally leads to protein unfolding, implying, in accordance with Le Chatelier's principle, that the unfolded state has a smaller molar volume than the folded state. However, the origin of the volume change upon unfolding, ΔV(u), has yet to be determined. We have examined systematically the effects of protein size and sequence on the value of ΔV(u) using as a model system a series of deletion variants of the ankyrin repeat domain of the Notch receptor. The results provide strong evidence in support of the notion that the major contributing factor to pressure effects on proteins is their imperfect internal packing in the folded state. These packing defects appear to be specifically localized in the 3D structure, in contrast to the uniformly distributed effects of temperature and denaturants that depend upon hydration of exposed surface area upon unfolding. Given its local nature, the extent to which pressure globally affects protein structure can inform on the degree of cooperativity and long-range coupling intrinsic to the folded state. We also show that the energetics of the protein's conformations can significantly modulate their volumetric properties, providing further insight into protein stability.

Variación del grado de avance de reacción en sistemas cerrados en equilibrio químico que modifican la temperatura a volumen constante

In this paper it is presented a thermodynamic analysis that aims to find the mathematical expression of the variation of extent of reaction with the infinitesimal variation in the temperature at constant volume of a chemical equilibrium mixture. The goal of this paper is to establish an alternative approach to avoid both the Le Chatelier's principle and the problems that emerge when trying to apply its qualitative statements. This attempt is based on the laws of thermodynamics.

Renewable Energy Driven by Le Chatelier's Principle, Enzyme Function, and Non-Additive Contributions to Ion Fluctuations: A Hypothesis in Biomechanical and Nanotechnology Energy Theory

The search for green energy sources has populated the research arena with significant emphasis on green electronics, green fuels, and green batteries that reduce waste, emissions, and environmental toxicity. Simultaneously, nanotechnology has developed substantially in the recent years and the emerging area of nanoenergetics has shown impressive discoveries that can aid in the search for alternative and green energies. The use of exotic materials in these fields and even enzymes has led scientists to be able to cross-link biomolecules and nanotechnology circuits, which can be important points in the search of novel energy searches. This paper discusses a biochemical energy-generating unit driven by ion fluctuations and spontaneous enzyme conformational changes. The paper lays also the theoretical thermodynamical foundation of the nanoenergy unit and to exploit the principle of nonadditivity and equilibrium as main forces in driving an energy-generating reaction.

DECAB: Process development of a phase change absorption process

This work describes the conceptual design of a novel separation process for CO2 removal from flue gas based on precipitating solvents. The process here described (DECAB) is an enhanced CO2 absorption based on the Le Chatelier's principle, which states that reaction equilibrium can be shifted by removing one of the constituents in the reaction. A conceptual design of this process has been developed based on literature data, thermodynamic principles and a limited number of experiments. As solvent example, the potassium salt of taurine was selected. The strategy followed is based on the compilation and determination of the key properties and parameters that govern the absorption and regeneration of the solvent. Then, the performance of the process is evaluated with the aid of short cut design methods. Results show that the key advantages of this process are environmental friendliness (no emissions to the air) and low energy consumption related to a lower vapor pressure of the solvent and higher net loading than conventional processes. The design developed allows for future economic evaluation and assessment of options that will further lead to benefits over conventional processes. © 2011 Published by Elsevier Ltd.

Effects of the impurity–host interactions on the nonradiative processes in ZnS:Cr

There is a great deal of controversy about whether the behavior of an intermediate band in the gap of semiconductors is similar or not to the deep-gap levels. It can have significant consequences, for example, on the nonradiative recombination. In order to analyze the behavior of an intermediate band, we have considered the effect of the inward and outward displacements corresponding to breathing and longitudinal modes of Cr-doped ZnS and on the charge density for different processes involved in the nonradiative recombination using first-principles. This metal-doped zinc chalcogenide has a partially filled band within the host semiconductor gap. In contrast to the properties exhibited by deep-gap levels in other systems, we find small variations in the equilibrium configurations, forces, and electronic density around the Cr when the nonradiative recombination mechanisms modify the intermediate band charge. The charge density around the impurity is equilibrated in response to the perturbations in the equilibrium nuclear configuration and the charge of the intermediate band. The equilibration follows a Le Chatelier principle through the modification of the contribution from the impurity to the intermediate band and to the valence band. The intermediate band introduced by Cr in ZnS for the concentrations analyzed makes the electronic capture difficult and later multiphonon emission in the charge-transfer processes, in accordance with experimental results.

ChemInform Abstract: Chemistry of Potentially Prebiological Natural Products

A relationship between what might be called a kinetic version of Le Chatelier's principle and chemical self-organization is considered. Some aspects of the search for a pre-RNA genetic system are discussed. Results of an experimental investigation on the pairing properties of alternative nucleic acid systems — including those of pyranosyl-RNA (‘p-RNA’), a constitutional isomer of RNA — are summarized.

Optimization of the sintering atmosphere for high-density hydroxyapatite–carbon nanotube composites

Hydroxyapatite-carbon nanotube (HA-CNT) composites have the potential for improved mechanical properties over HA for use in bone graft applications. Finding an appropriate sintering atmosphere for this composite presents a dilemma, as HA requires water in the sintering atmosphere to remain phase pure and well hydroxylated, yet CNTs oxidize at the high temperatures required for sintering. The purpose of this study was to optimize the atmosphere for sintering these composites. While the reaction between carbon and water to form carbon monoxide and hydrogen at high temperatures (known as the 'water-gas reaction') would seem to present a problem for sintering these composites, Le Chatelier's principle suggests this reaction can be suppressed by increasing the concentration of carbon monoxide and hydrogen relative to the concentration of carbon and water, so as to retain the CNTs and keep the HA's structure intact. Eight sintering atmospheres were investigated, including standard atmospheres (such as air and wet Ar), as well as atmospheres based on the water-gas reaction. It was found that sintering in an atmosphere of carbon monoxide and hydrogen, with a small amount of water added, resulted in an optimal combination of phase purity, hydroxylation, CNT retention and density.

Hydrolysis of CuCl 2 in the Cu–Cl thermochemical cycle for hydrogen production: Experimental studies using a spray reactor with an ultrasonic atomizer

The Cu–Cl thermochemical cycle is being developed as a hydrogen production method. Prior proof-of-concept experimental work has shown that the chemistry is viable while preliminary modeling has shown that the efficiency and cost of hydrogen production have the potential to meet DOE's targets. However, the mechanisms of CuCl 2 hydrolysis, an important step in the Cu–Cl cycle, are not fully understood. Although the stoichiometry of the hydrolysis reaction, 2CuCl 2 + H 2O ↔ Cu 2OCl 2 + 2HCl, indicates a necessary steam-to-CuCl 2 molar ratio of 0.5, a ratio as high as 23 has been typically required to obtain near 100% conversion of the CuCl 2 to the desired products at atmospheric pressure. It is highly desirable to conduct this reaction with less excess steam to improve the process efficiency. Per Le Chatelier's Principle and according to the available equilibrium-based model, the needed amount of steam can be decreased by conducting the hydrolysis reaction at a reduced pressure. In the present work, the experimental setup was modified to allow CuCl 2 hydrolysis in the pressure range of 0.4–1 atm. Chemical and XRD analyses of the product compositions revealed the optimal steam-to-CuCl 2 molar ratio to be 20–23 at 1 atm pressure. The experiments at 0.4 atm and 0.7 atm showed that it is possible to lower the steam-to-CuCl 2 molar ratio to 15, while still obtaining good yields of the desired products. An important effect of running the reaction at reduced pressure is the significant decrease of CuCl concentration in the solid products, which was not predicted by prior modeling. Possible explanations based on kinetics and residence times are suggested.

Le Chatelier's principle in sensation and perception: fractal-like enfolding at different scales

Le Chatelier's principle asserts that a disturbance, when applied to a resting system may drive the system away from its equilibrium state, but will invoke a countervailing influence that will counteract the effect of the disturbance. When applied to the field of sensation and perception, a generalized stimulus will displace the system from equilibrium, and a generalized adaptation process will serve as the countervailing influence tending to reduce the impact of the stimulus. The principle applies at all levels, from the behavioral to the neural, the larger enfolding the smaller in fractal-like form. Le Chatelier's principle, so applied, leads to the unification of many concepts in sensory science. Ideas as diverse as sensory adaptation, reflex arcs, and simple deductive logic can be brought under the umbrella of a single orienting principle. Beyond unification, this principle allows us to approach many questions in pathophysiology from a different perspective. For example, we find new direction toward the reduction of phantom-limb pain and possibly of vertigo.

Extrusion-like chip formation mechanism and its role in suppressing void nucleation

The mechanism of chip formation transforms from concentrated shearing to an extrusion-like behavior at a critical combination of undeformed chip thickness and tool edge radius. Finite element analysis shows that material is removed by severe deviatoric stress within the boundary of elastic–plastic deformation during extrusion-like chip formation while this boundary is constantly redistributed to accommodate chip growth. Simultaneously, the deformation region is contained within active compressive components and hydrostatic pressure as chips are extruded. Under such operating conditions, void nucleation is prevented according to the Le-Chatelier's principle. Exceptional surface finish was produced experimentally through the extrusion-like chip formation mechanism.

An error corrected almost ideal demand system for major cereals in Kenya

AbstractDespite significant progress in theory and empirical methods, the analysis of food consumption patterns in developing countries, particularly those in Sub‐Saharan Africa (SSA), has received very limited attention. An attempt is made in this article to estimate an Error Corrected Almost Ideal Demand System for four major cereals consumed in Kenya employing annual data from 1963 to 2005. This demand system performs well on both theoretical and empirical grounds. The symmetry and homogeneity conditions are supported by the data and the Le Chatelier principle holds. Empirically, all own‐price elasticities are negative and significant at 5% level and irrespective of the time horizon, maize, wheat, rice, and sorghum may be considered as necessities in Kenya. While the expenditure elasticities of all four cereals are positive, they are inelastic both in the short run and in the long run. Finally, wheat and rice complement maize consumption in Kenya while sorghum acts as a substitute. Since cereal consumers have price and income inelastic responses, a combination of income and price‐oriented policies could improve cereal consumption in Kenya.

On violations of Le Chatelier’s principle for a temperature change in small systems observed for short times

Le Chatelier's principle states that when a system is disturbed, it will shift its equilibrium to counteract the disturbance. However for a chemical reaction in a small, confined system, the probability of observing it proceed in the opposite direction to that predicted by Le Chatelier's principle, can be significant. This work gives a molecular level proof of Le Chatelier's principle for the case of a temperature change. Moreover, a new, exact mathematical expression is derived that is valid for arbitrary system sizes and gives the relative probability that a single experiment will proceed in the endothermic or exothermic direction, in terms of a microscopic phase function. We show that the average of the time integral of this function is the maximum possible value of the purely irreversible entropy production for the thermal relaxation process. Our result is tested against computer simulations of the unfolding of a polypeptide. We prove that any equilibrium reaction mixture on average responds to a temperature increase by shifting its point of equilibrium in the endothermic direction.

Chemistry misconceptions associated with understanding calcium and phosphate homeostasis

Successful learning of many aspects in physiology depends on a meaningful understanding of fundamental chemistry concepts. Two conceptual diagnostic questions measured student understanding of the chemical equilibrium underlying calcium and phosphate homeostasis. One question assessed the ability to predict the change in phosphate concentration when calcium ions were added to a saturated calcium phosphate solution. Fifty-two percent of the students correctly predicted that the phosphate concentration would decrease in accord with the common ion effect. Forty-two percent of the students predicted that the phosphate concentration would not change. Written explanations showed that most students failed to evoke the idea of competing chemical equilibria. A second question assessed the predicted change in calcium concentration after solid calcium phosphate was added to a saturated solution. Only 11% of the students correctly predicted no change in calcium concentration; 86% of the students predicted an increase, and many based their prediction on a mistaken application of Le Chatelier's principle to heterogeneous equilibria. These results indicate that many students possess misconceptions about chemical equilibrium that may hamper understanding of the processes of calcium and phosphate homeostasis. Instructors can help students gain greater understanding of these physiochemical phenomena by adopting strategies that enable students achieve more accurate conceptions of chemical equilibria.

The LeChatelier principle in a DEA model

Abstract This paper aims to relate the LeChatelier principle, first introduced into economics by Samuelson (1947), with the DEA approach through two propositions. These propositions allow for bridging the principle over a DEA model with and without the presence of non-discretionary inputs and enable one to make comparisons for the various efficiency measures under different conditions. The quasi-fixity of some inputs hinders a firm’s capacity from instantly and freely adjusting its input combination in order to minimize its production costs. The assumption that all inputs are discretionary tends to exaggerate managers’ ability to dispense resources and renders invalid information on the adjustment of the current input mix.

The effect of marketing regulations on efficiency: LeChatelier versus coordination effects

Government regulations designed to promote social welfare can have unintended consequences on efficiency. According to the LeChatelier Principle, regulations that effectively limit substitution possibilities among inputs will reduce firm and industry-wide efficiency. In imperfectly competitive markets, however, government constraints on a strategic variable can facilitate coordination. An advertising restriction, for example, would improve efficiency if it enables firms to produce the same level of sales with less advertising spending. We use data envelopment analysis to estimate the effect of marketing regulations on efficiency in the U.S. cigarette industry. Unlike previous studies, we do not assume that marketing and production technologies are separable. Our results demonstrate that coordination effects dominate LeChatelier effects. Cigarette producers have benefited from advertising restrictions, a result consistent with the capture theory of regulation.

The global LeChatelier Principle and multimarket equilibria

LeChatelier (Comptes Rendus 99:786, 1884) and LeChatelier (Ann Mines 13(2):157, 1888) proposed that the adjustment of a physical system to a disturbance in its equilibrium was smaller as constraints are added to the adjustment process. Samuelson (Econometrica 28:368–379, 1960) showed that this Principle applied to a stable multimarket equilibrium for the case that all commodities are gross substitutes. We note that the Principle also applies to the stable equilibria of markets for which commodities can also be gross complements as formulated by Morishima (Osaka Econ Pap 1:101–113, 1952). Further, the Morishima and gross substitute cases are the only cases to which the Principle can apply, based only upon the stability hypothesis and a specification of the gross substitute/complement relations among commodities. We show that the Milgrom and Shannon (Econometrica 62:157–180, 1994) single crossing conditions specified for monotone comparative statics can be configured appropriate to the Morishima case to give global conditions for the LeChatelier Principle to apply to a multimarket equilibrium.

Growth Inhibition to Enhance Conformal Coverage in Thin Film Chemical Vapor Deposition

We introduce the use of a growth inhibitor to enhance thin film conformality in low temperature chemical vapor deposition. Films of TiB(2) grown from the single source precursor Ti(BH(4))(3)(dme) are much more highly conformal when grown in the presence of one of the film growth byproducts, 1,2-dimethoxyethane (dme). This effect can be explained in terms of two alternative inhibitory mechanisms: one involving blocking of surface reactive sites, which is equivalent to reducing the rate of the forward reaction leading to film growth, the other analogous to Le Chatelier's principle, in which the addition of a reaction product increases the rate of the back reaction. The reduction in growth rate corresponds to a reduction in the sticking probability of the precursor, which enhances conformality by enabling the precursor to diffuse deeper into a recessed feature before it reacts.

Cluster mechanism of the anti-greenhouse effect

The Earth’s atmosphere is a complex dynamic system, which protects the biosphere. One of the significant factors impacting Earth’s radiation balance is the greenhouse effect. Its enhancement is not only due to an increase in solar activity but also due to an increase in the content of gases with pronounced radiation properties in the atmosphere. Water vapor and atmospheric gases, such as CO 2 , CH 4 , N 2 O, and others, have a decisive influence on the formation of thermal radiation fields. However, according to the Le Chatelier principle, there are opposite compensating processes in the atmosphere. Clustering of greenhouse gases can be considered as one of these processes. The autoregulation of the atmosphere composition due to the formation of water clusters and their subsequent capture of greenhouse gas molecules is, as a rule, ignored in estimates of Earth’s radiation balance. The characteristics of infrared (IR) radiation absorption by water clusters incorporating molecules of the most abundant atmospheric gases—nitrogen, oxygen, and argon—were studied in [1‐4]. This work deals with the molecular dynamics study of the influence of clustering of H 2 O vapor and atmospheric gases CO 2 , N 2 O, CH 4 , C 2 H 2 , and C 2 H 6 on the greenhouse effect. The IR absorption spectra were calculated for systems formed by water clusters and molecules of the above greenhouse gases at 233 K. Due to clustering, a homogeneous single-phase system represented by a mixture of gases transforms into a “twophase” or even “three-phase” state since, depending on the ambient conditions, clusters constituting a fine “phase” can be in both the liquid and solid states. Water clusters were simulated using the improved interaction potential TIP4P for water and the rigid foursite model of H 2 O molecules [5]. To determine the influence of absorbed polyatomic molecules on the greenhouse effect, we considered different types of ultradisperse systems: (H 2 O) n (I), (CO 2 ) i (H 2 O) 10 (II), (CH 4 ) i (H 2 O) 10 (III), (N 2 O) i (H 2 O) 10 (IV), (C 2 H 2 ) m (H 2 O) 20 (V), and (C 2 H 6 ) m (H 2 O) 20 (VI), where n = 10–20 , i = 1–10 , and m = 1‐6. The calculation of the autocorrelation function of the total dipole moment M of the clusters makes it possible to determine their IR spectra, which characterize absorption coefficients [6]. The IR radiation absorption cross section was specified by the equation [7]