Isothermal Approach Research Articles

The Discovery of Rolling Circle Amplification and Rolling Circle Transcription

Nucleic acid amplification is a hugely important technology for biology and medicine. While the polymerase chain reaction (PCR) has been highly useful and effective, its reliance on heating and cooling cycles places some constraints on its utility. For example, the heating step of PCR can destroy biological molecules under investigation and heat/cool cycles are not applicable in living systems. Thus, isothermal approaches to DNA and RNA amplification are under widespread study. Perhaps the simplest of these are the rolling circle approaches, including rolling circle amplification (RCA) and rolling circle transcription (RCT). In this strategy, a very small circular oligonucleotide (e.g., 25-100 nucleotides in length) acts as a template for a DNA or an RNA polymerase, producing long repeating product strands that serve as amplified copies of the circle sequence. Here we describe the early developments and studies involving circular oligonucleotides that ultimately led to the burgeoning rolling circle technologies currently under development. This Account starts with our studies on the design of circular oligonucleotides as novel DNA- and RNA-binding motifs. We describe how we developed chemical and biochemical strategies for synthesis of well-defined circular oligonucleotides having defined sequence and open (unpaired) structure, and we outline the unusual ways in which circular DNAs can interact with other nucleic acids. We proceed next to the discovery of DNA and RNA polymerase activity on these very small cyclic DNAs. DNA polymerase "rolling circle" activities were discovered concurrently in our laboratory and that of Andrew Fire. We describe the surprising efficiency of this process even on shockingly small circular DNAs, producing repeating DNAs thousands of nucleotides in length. RNA polymerase activity on circular oligonucleotides was first documented in our group in 1995; especially surprising in this case was the finding that the process occurs efficiently even without promoter sequences in the circle. We describe how one can encode cleavable sites into the product DNAs and RNAs from RCA/RCT, which can then be resolved into large quantities of almost pure oligonucleotides. Our Account then proceeds with a summary describing a broad variety of tools and methods built in many laboratories around the rolling circle concept. Among the important developments are the discovery of highly efficient DNA polymerases for RCA; the invention of exponential ("hyperbranched") RCA amplification made possible by use of a second primer; the development of the "padlock" process for detection of nucleic acids and proteins coupled with RCA; the use of circular oligonucleotides as vectors in cells to encode biologically active RNAs via RCT; and the use of small DNA circles to encode and extend human telomeres. Finally, we finish with some ideas about where the field may go in the future.

A Comparison of the Pyrolysis of Olive Kernel Biomass in Fluidised and Fixed Bed Conditions

The use of thermogravimetric analysis to describe biomass kinetics often uses bench top thermogravimetric analyser (TGA) analysers which are only capable of low heating rates. The aim of this research was to compare experimental fast pyrolysis of Olive kernels in a bespoke laboratory thermogravimetric fluidised bed reactor (TGFBR) characterised by rapid heating rates at high flow rates, compared to a smaller bench scale fixed bed TGA system. The pyrolysis in the TGFBR was analysed by using the isothermal kinetic approach and it was theorised that the pyrolysis decomposition reactions occurred by two mechanisms depending on the temperature, resulting in an activation energy of 67.4 kJ/mol at temperatures below <500 °C and 60.8 kJ/mol at temperatures >500 °C. For comparison, a bench scale TGA was used to look at the thermal behaviour in different fixed bed thermal conditions giving a higher activation energy of 74.4 kJ/mol due to the effect of external particle gas diffusion. The effect of biomass particle size (0.3–4.0 mm) on the conversion of biomass at different temperatures, was investigated between 300 and 660 °C in the TGFBR. The results suggested inhibition of internal gas diffusion was more important at lower temperatures, but in comparison had no significant effect when measured in the fixed bed TGA at lower heating rates. Bench top TGA analysis of pyrolysis is a rapid and valuable method, but is limited by smaller sample sizes and lower heating rates. In comparison, the conditions encountered with the laboratory scale TGFBR are more likely to be relevant to larger scale systems where heat distribution, heat transfer and mass diffusion effects play major roles in the reactivity of biomass.

Demonstration of a Solar Reactor for Carbon Dioxide Splitting via the Isothermal Ceria Redox Cycle and Practical Implications

The performance of a 4.4 kW solar receiver/reactor to split carbon dioxide via the isothermal cerium dioxide thermochemical redox cycle is characterized during steady-state operation in a high-flux solar simulator. The solar reactor is the first to implement the isothermal redox cycle. Design innovations for continuous fuel production and gas-phase heat recuperation distinguish it from prior works. During steady-periodic operation at 1750 K, 360 mL min–1 of CO is produced continuously over 45 redox cycles, and up to 95% of the sensible heat of the process gases is recovered. The solar-to-fuel efficiency is 1.64% without consideration of the energy costs of producing nitrogen used as a sweep gas during reduction. With inclusion of the solar energy required to produce N2 via cryogenic separation, the efficiency is 0.72%. On the basis of the thermodynamic limitations of the cycle and the limited opportunity for increasing reactor efficiency beyond 2%, we conclude that the isothermal approach to split CO2 or ...

Multi-model attribution of upper-ocean temperature changes using an isothermal approach.

Both air-sea heat exchanges and changes in ocean advection have contributed to observed upper-ocean warming most evident in the late-twentieth century. However, it is predominantly via changes in air-sea heat fluxes that human-induced climate forcings, such as increasing greenhouse gases, and other natural factors such as volcanic aerosols, have influenced global ocean heat content. The present study builds on previous work using two different indicators of upper-ocean temperature changes for the detection of both anthropogenic and natural external climate forcings. Using simulations from phase 5 of the Coupled Model Intercomparison Project, we compare mean temperatures above a fixed isotherm with the more widely adopted approach of using a fixed depth. We present the first multi-model ensemble detection and attribution analysis using the fixed isotherm approach to robustly detect both anthropogenic and natural external influences on upper-ocean temperatures. Although contributions from multidecadal natural variability cannot be fully removed, both the large multi-model ensemble size and properties of the isotherm analysis reduce internal variability of the ocean, resulting in better observation-model comparison of temperature changes since the 1950s. We further show that the high temporal resolution afforded by the isotherm analysis is required to detect natural external influences such as volcanic cooling events in the upper-ocean because the radiative effect of volcanic forcings is short-lived.

Ion exchange at the critical point of solution

A mixture of isobutyric acid (IBA)+water has an upper critical point of solution at 26.7°C and an IBA concentration of 4.40M. We have determined the Langmuir isotherms for the hydroxide form of Amberlite IRN-78 resin in contact with mixtures of IBA+water at temperatures, 27.0, 29.0, 31.0 and 38.0°C, respectively. The Langmuir plot at 38.0°C forms a straight line. At the three lower temperatures, however, a peak in the Langmuir plot is observed for IBA concentrations in the vicinity of 4.40M. We regard this peak to be a critical effect not only because it is located close to 4.40M, but also because its height becomes more pronounced as the temperature of the isotherm approaches the critical temperature. For concentrations in the vicinity of the peak, the data indicate that the larger isobutyrate ion is rejected by the resin in favor of the smaller hydroxide ion. This reversal of the expected ion exchange reaction might be used to separate ions according to size. Using the Donnan theory of ion exchange equilibrium, we link the swelling pressure to the osmotic pressure. We show that the peak in the Langmuir plot is associated with a maximum in the “osmotic” energy. This maximum has its origin in the concentration derivative of the osmotic pressure, which goes to zero as the critical point is approached.

Automatic correction of the time step in implicit simulations of thermomechanical problems

The accurate numerical modelling of thermomechanical systems is important in several industrial applications. A new staggered coupling strategy is proposed to deal with thermo-elasto-plastic problems involving large deformations and rotations, which is combined with an automatic time-step control technique. The proposed strategy is based on the isothermal split approach. It differs from the classical scheme since, in each increment, there are two phases of interchange of information, instead of only one. In each increment, the solution procedure is divided in a prediction phase and a corrector phase, and the interchange of information is performed on both. The proposed strategy was implemented in the in-house quasi-static finite element code DD3IMP. Its performance is analysed and compared with the classical strategy and the iterative one, which are commonly employed for solving thermomechanical problems. The results indicate that the propose strategy contributes for improving the accuracy of the numerical solution, with a reasonable computational cost.

Vapour adsorption kinetics: statistical rate theory and zeta adsorption isotherm approach.

The equilibrium zeta adsorption isotherm for vapours indicates the amount adsorbed is finite for vapour-phase pressures approaching the saturation value, and is strongly supported by experimental measurements for a number of different vapour-solid surface systems. This isotherm assumes the adsorbate consists of differently sized molecular clusters in local equilibrium rather than the adsorbate being in layers. We use the local-equilibrium approximation and develop a method to determine the expression for chemical potential of the adsorbate in terms of the amount adsorbed, nA(t). This allows us to apply statistical rate theory to calculate nA(t) at five different vapour-phase pressures, xV (≡PV/Psat), in terms of a parameter, re. Statistical rate theory indicates that re describes the dynamics of a given isolated system under equilibrium conditions. We consider two methods for determining the value of re that give the best agreement with the measurements performed at each of five values of xV. In one method, we assume, re, is a function of both temperature, T, and pressure, xV, and determine the five best-fit values of re. In the experiments, xV changes by a factor of more than two, but the standard deviation in the re values is 6%. In the second method, we assume re is a function only of T; and find that the value of re is not changed significantly. In all cases, the calculated nA(t) agree with the measurements.

VolcFlow capabilities and potential development for the simulation of lava flows

Abstract VolcFlow is a finite-difference Eulerian code based on the depth-averaged approach and developed for the simulation of isothermal geophysical flows. Its capability for reproducing lava flows is tested here for the first time. The field example chosen is the 2010 lava flow of Tungurahua volcano (Ecuador), the emplacement of which is tracked by projecting thermal images onto a georeferenced digital topography. Results show that, at least for this case study, the isothermal approach of VolcFlow is able to simulate the velocity of the lava through time, as well as the extent of the solidified lava. However, the good fit between the modelled and the natural flow may be explained by the short emplacement time ( c. 20 h) of a thick lava ( c. 5 m), which could limit the influence of cooling on the flow dynamics, thus favouring the use of an isothermal rheology.

Characterization of the Pore Structure and Surface Properties of Shale Using the Zeta Adsorption Isotherm Approach

The determination of the specific surface area and pore structure parameters of natural materials have been a long-standing issue. We propose a method for determining the specific surface area and pore size distribution that is based on the zeta adsorption isotherm and apply that method for each of two hydrocarbon vapors, octane and heptane, adsorbing on two types of shale, as-received and milled shale. We determined the specific surface areas of both materials, approximate the pores as cylindrical, and determine the average pore mouth radius. The standard deviation in the mean values of the specific surface areas and average pore radius determined with each of the two vapors is less than 3%. The experimental isotherms on the as-received shale indicate the existence of a pronounced adsorption–desorption hysteresis loop that results from the mesoporous structure of the material. We previously showed that liquid forms in the pores because of coalescence of molecular clusters inside the pores. In this study, we show that the pore emptying in the as-received shale is delayed because of the pore blocking effect. The zeta isotherm theory and the necessary conditions for thermodynamic equilibrium along with the measured amount adsorbed are used to determine the distribution in the pore mouth radii.

Life estimation methodology for short fiber reinforced polymers under thermo‐mechanical loading in automotive applications

In this paper a FE based lifetime assessment methodology for short glass fiber reinforced polybutylene terephthalate (PBT‐GF30) under thermo‐mechanical fatigue (TMF) loading is presented.In order to investigate the fatigue behavior of the material both isothermal strain controlled fatigue (ISCF) tests at four different temperatures and thermo‐mechanical fatigue tests were conducted on plain and notched specimens.Through a comparative microscopic investigation of thermo‐mechanical fatigue fracture surfaces and isothermal strain controlled fatigue fracture surfaces created at different temperatures the material state (i.e. the temperature) at which thermo‐mechanical fatigue failure occurs was determined.On the basis of this insight a life estimation methodology derived from a strain energy density (SED) based approach was developed for the corresponding isothermal strain controlled fatigue load case [1]. Through consideration of additional effects occurring during thermo‐mechanical fatigue testing (i.e. relaxation, spatial temperature gradients, creep damage due to low testing frequencies and plastic overloads) the isothermal approach was successfully adapted to the thermo‐mechanical fatigue load case.

Negative-saturation approach for (non)-isothermal compositional three-phase flow simulations in porous media

This article describes the extension of the two-phase (non)-isothermal negative-saturation solution approach to the three-phase (non)-isothermal negative-saturation (NegSat3) solution approach. The NegSat3 solution approach solves efficiently any (non)-isothermal compositional flow problem in porous media that involves phase transitions between different phase states when the maximum number of phases is less than four. The solution approach circumvents using different equations and primary variables for single-phase, two-phase, and three-phase regions in porous media. Consequently, the NegSat3 solution approach avoids switches or variable substitutions at phase transitions where the convergence of the Newton-Raphson procedure is hampered by oscillations between m-phase and n-phase states. The NegSat3 solution approach can be implemented efficiently in numerical simulators to deal with modeling issues for thermal recovery processes, CO2 sequestration, and for multicontact miscible gas injection in oil reservoirs if the number of phases is less than four. We illustrate the NegSat3 solution approach by way of example to steam injection in a 1D heavy-oil reservoir. However, the NegSat3 solution approach can be used for any n ≤ 3-dimensional, multicomponent three-phase problems. The example solution is compared with a standard numerical solution that is analytically verified by the method of characteristics and shows excellent agreement. The results show that the oil recovery depends critically on whether the boiling temperature of the volatile oil is around the water boiling temperature, or much below or above it. These boiling-temperature ranges give rise to three different types of wave structures. When the boiling temperature of the volatile oil is near the boiling temperature of water, the striking result is that the speed of the evaporation front is equal or somewhat larger than the speed of the steam-condensation front. Thus, the volatile oil condenses at the location where the steam condenses too, yielding virtually complete oil recovery. Conversely, if the boiling temperature is too high or too low, there is incomplete recovery.

Solubility and Some Crystallization Properties of Conglomerate Forming Chiral Drug Guaifenesin in Water

The solubility of 3-(2-methoxyphenoxy)-propane-1,2-diol, the well-known chiral drug guaifenesin 1, in water has been investigated by means of polythermal and isothermal approaches. It was found that the solubilities of racemic and enantiomeric diols rac- and (R)-1 depend strongly on temperature. The ternary phase diagram of the guaifenesin enantiomers in water in the temperature range between 10°C and 40°C was constructed. Clear evidence was obtained that rac-1 crystallizes as a stable conglomerate. The Meyerhoffer coefficient for the guaifenesin-water system is more than two and strongly depends on temperature. Neither crystalline hydrates nor polymorphs were detected within the range of conditions covered. Metastable zone width data with regard to primary nucleation were also collected for rac-1 and (R)-1. On the basis of the knowledge acquired, the resolution of racemic guaifenesin by preferential crystallization from solution could be realized successfully.

Thermo‐mechanical couplings in elastomers – experiments and modelling

Elastomers take an important role in many industrial applications. In the automotive industries for example, elastomers are used in various bearings, where they inhibit vibration propagation and thereby significantly enhance driving performance and comfort. Several models have been developed to simulate the material's mechanical response to various stresses and strains a component may undergo during its lifetime. So far, these models are commonly developed under isothermal conditions. In this contribution it is shown that the mechanical properties significantly depend on the temperature and that the material heats up under large dynamic deformations. Therefore, an elastomer's behaviour is not described sufficiently with an isothermal approach, a detailed thermo‐viscoelastic modelling is required. In this contribution, the behaviour of elastomers is experimentally investigated in order to gain informations about the time‐ and temperature‐dependent mechanical properties. We perform different tests on a natural rubber to emphasize the temperature dependence of the equilibrium stress‐strain relation as well as the time‐dependent behaviour in relaxation tests. As it is necessary for parameterising a material model, thermal tests are carried out to determine the specific heat capacity, the thermal expansion coefficient and the thermal conductivity. In a second step, we introduce a material model which is able to represent the temperature‐dependent viscoelastic material behaviour including large deformations, as well as the self‐heating of the material. The model's mechanical parameters are identified on tension tests. In first FE calculations, the applicability of the introduced model is proven by depicting the experimental results of several tension tests at different temperatures. Besides these validations, the self‐heating under dynamic load, depending on the loads amplitude and frequency as well as the surrounding temperature is calculated.

A study of interfacial adsorption isotherm at divided interface for novel macrocycles in solvent extraction

A new aspect of liquid–liquid extraction by using the adsorption isotherm approach at divided interface was described. In order to explain complexation behavior of ligands, extraction of ions in the interfacial region of liquid–liquid phase can be modeled by Langmuir adsorption isotherm. A series of macrocycles of different ring sizes with different type of donor atoms has been synthesized and characterized by several spectroscopic techniques. Solvent extraction method was used to evaluate metal-ion binding properties of the macrocycles. The values of the extraction constants and the complex compositions were determined for the extracted complexes. Macrocycles 2 and 3 as extractant of silver cation from aqueous solution at different temperatures and concentrations was investigated. Kinetics and thermodynamic parameters of the interfacial adsorption were also investigated. The cation-binding affinity of macrocyclic ligand 2 among the other ligands for Ag+ over other cations in both organic solvents was found to be the highest. The Ag+ ion was extracted by 88.3 and 81.7 % to the dichloromethane and chloroform phase with macrocycle 2, respectively. The maximum metal ion adsorption capacity (28 %) was found for macrocycle 2 at 20 °C.

Rapid Molecular Assays for the Detection of Yellow Fever Virus in Low-Resource Settings

BackgroundYellow fever (YF) is an acute viral hemorrhagic disease transmitted by Aedes mosquitoes. The causative agent, the yellow fever virus (YFV), is found in tropical and subtropical areas of South America and Africa. Although a vaccine is available since the 1930s, YF still causes thousands of deaths and several outbreaks have recently occurred in Africa. Therefore, rapid and reliable diagnostic methods easy to perform in low-resources settings could have a major impact on early detection of outbreaks and implementation of appropriate response strategies such as vaccination and/or vector control.MethodologyThe aim of this study was to develop a YFV nucleic acid detection method applicable in outbreak investigations and surveillance studies in low-resource and field settings. The method should be simple, robust, rapid and reliable. Therefore, we adopted an isothermal approach and developed a recombinase polymerase amplification (RPA) assay which can be performed with a small portable instrument and easy-to-use lyophilized reagents. The assay was developed in three different formats (real-time with or without microfluidic semi-automated system and lateral-flow assay) to evaluate their application for different purposes. Analytical specificity and sensitivity were evaluated with a wide panel of viruses and serial dilutions of YFV RNA. Mosquito pools and spiked human plasma samples were also tested for assay validation. Finally, real-time RPA in portable format was tested under field conditions in Senegal.Conclusion/SignificanceThe assay was able to detect 20 different YFV strains and demonstrated no cross-reactions with closely related viruses. The RPA assay proved to be a robust, portable method with a low detection limit (<21 genome equivalent copies per reaction) and rapid processing time (<20 min). Results from real-time RPA field testing were comparable to results obtained in the laboratory, thus confirming our method is suitable for YFV detection in low-resource settings.

Experimental Method on Rapid Identification of Autocatalysis in Decomposition Reactions

Many chemical substances will decompose in an autocatalytic manner, and such autocatalytic behavior can be identified through isothermal measurements, such as using differential scanning calorimetry(DSC) and microcalorimetry(C80). However, since it is difficult to predict the appropriate temperature for isothermal testing, it would be helpful to develop a simple and effective experimental method to distinguish autocatalytic decomposition. Based on the results of Roduit et al., a new technique for identifying autocatalysis is described herein, termed the"interruption and re-scanning"method. The decompositions of 2-ethylhexyl nitrate(EHN), 2,4-dinitrotoluene(2,4-DNT), dicumyl peroxide(DCP), and cumyl hydroperoxide(CHP) were assessed using both this new method and isothermal approach. Based on the results, the decompositions of EHN and DCP were found to proceed accord to the"nth order"law,whereas 2,4-DNT and CHP decomposed autocatalytically. We conclude that the interruption and rescanning method can be used to identify the characteristics of autocatalysis both quickly and effectively.

Clusters in the adsorbates of vapours and gases: zeta isotherm approach.

A procedure for determining the structure of vapour and gas adsorbates that is based on the Zeta adsorption isotherm is reported. For vapours and for gases, this isotherm supposes that an adsorbate consists of particle clusters with the number of particles in a cluster denoted ζ, where ζ can be 1, 2, 3… up to a maximum of ζm, and predicts the isotherm constants are independent of pressure. For vapours, this allows the isotherm constants to be determined from isotherm measurements made at pressures less than the saturation-vapour pressure, Ps, but applied at pressures greater than Ps. Since ζ has an upper limit, we show that there are no singularities in the vapour or gas adsorption isotherms for any pressure. This allows the adsorption of vapours at pressures greater than Ps to be investigated: clusters with ζm molecules are predicted to increase in number as P(V) is increased, until they form an adsorbed film with each adsorption site occupied by a ζm-cluster. We apply the same procedure to determine the value of ζm for gas adsorption. For CO adsorbing on Ni(100), ζm is predicted to be unity for all the cases considered, indicating that the adsorbate consists of adsorbed molecules without any clustering. For H2 adsorption on the three different materials, ζm is found to be two: indicating the adsorbate consists of both adsorbed molecules and atoms. For each material considered, a pressure is predicted where the mole fractions of both are equal, and at higher pressure, the mole fraction of adsorbed molecules exceeds that of the adsorbed atoms.

Modeling of rare earth element sorption to the Gram positive Bacillus subtilis bacteria surface

In this study, rare earth element (REE) binding constants and site concentration on the Gram+ bacteria surfaces were quantified using a multi-site Langmuir isotherm model, along with a linear programming regression method (LPM), applied to fit experimental REE sorption data. This approach found one discrete REE binding site on the Gram+ Bacillus subtilis surface for the pH range of 2.5–4.5. Average log10 REE binding constants for a site j on these bacteria ranged from 1.08±0.04 to 1.40±0.04 for the light REE (LREE: La to Eu), and from 1.36±0.03 to 2.18±0.14 for the heavy REE (HREE: Gd to Lu) at the highest biomass concentration of 1.3g/L of B. subtilis bacteria. Similar values were obtained for bacteria concentrations of 0.39 and 0.67g/L indicating the independence of REE sorption constants on biomass concentration. Within the experimental pH range in this study, B. subtilis was shown to have a lower affinity for LREE (e.g. La, Ce, Pr, Nd) and a higher affinity for HREE (e.g. Tm, Yb, Lu) suggesting an enrichment of HREE on the surface of Gram+ bacteria. Total surface binding site concentrations of 6.73±0.06 to 5.67±0.06 and 5.53±0.07 to 4.54±0.03mol/g of bacteria were observed for LREE and HREE respectively, with the exception of Y, which showed a total site concentration of 9.53±0.03, and a log KREE,j of 1.46±0.02 for a biomass content of 1.3g/L. The difference in these values (e.g. a lower affinity and increased binding site concentration for LREE, and the contrary for the HREE) suggests a distinction between the LREE and HREE binding modes to the Gram+ bacteria reactive surface at low pH. This further implies that HREE may bind more than one monoprotic reactive group on the cell surface. A multisite Langmuir isotherm approach along with the LPM regression method, not requiring prior knowledge of the number or concentration of cell surface REE complexation sites, were able to distinguish between the sorption constant and binding site concentration patterns of LREE and HREE on the Gram+ B. subtilis surface. This approach quantified the enrichment of Tm, Yb and Lu on the bacteria surface and it has therefore proven to be a useful tool for the study of natural reactive sorbent materials controlling REE partitioning in the natural environment.

The Preparation and Curing Kinetics of Epoxy/PhS(4, 4'-dihydroxydiphe-nylsulfone)/aluminum tris (tetradecylacetoacetate) Latent Resin System

In this paper, organic aluminum compound, aluminum tris (tetradecylacetoacetate) (Al-14) was synthesized, and its molecular structure was identified by IR spectrum. The investigation of the curing kinetic of epoxy resin system with PhS (4, 4-dihydroxydiphenylsulfone)/aluminum tris (tetradecylacetoacetate) (Al-14) latent catalysts was performed by differential scanning calorimetry (DSC) using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order and activation energy were calculated and reported. The results indicated that the curing reaction of Ep/PhS/Al-14 compand system in this experiment proceeded through an autocatalytic kinetic mechanism.

High-temperature isothermal chemical cycling for solar-driven fuel production

The possibility of producing chemical fuel (hydrogen) from the solar-thermal energy input using an isothermal cycling strategy is explored. The canonical thermochemical reactive oxide, ceria, is reduced under high temperature and inert sweep gas, and in the second step oxidized by H2O at the same temperature. The process takes advantage of the oxygen chemical potential difference between the inert sweep gas and high-temperature steam, the latter becoming more oxidizing with increasing temperature as a result of thermolysis. The isothermal operation relieves the need to achieve high solid-state heat recovery for high system efficiency, as is required in a conventional two-temperature process. Thermodynamic analysis underscores the importance of gas-phase heat recovery in the isothermal approach and suggests that attractive efficiencies may be practically achievable on the system level. However, with ceria as the reactive oxide, the isothermal approach is not viable at temperatures much below 1400 °C irrespective of heat recovery. Experimental investigations show that an isothermal cycle performed at 1500 °C can yield fuel at a rate of ~9.2 ml g(-1) h(-1), while providing exceptional system simplification relative to two-temperature cycling.