Curves Of Reactions Research Articles

Use of interactive mathematical simulations in Fundamentals of Biochemistry, a LibreText online educational resource, to promote understanding of dynamic reactions.

Biology is perhaps the most complex of the sciences, given the incredible variety of chemical species that are interconnected in spatial and temporal pathways that are daunting to understand. Their interconnections lead to emergent properties such as memory, consciousness, and recognition of self and non-self. To understand how these interconnected reactions lead to cellular life characterized by activation, inhibition, regulation, homeostasis, and adaptation, computational analyses and simulations are essential, a fact recognized by the biological communities. At the same time, students struggle to understand and apply binding and kinetic analyses for the simplest reactions such as the irreversible first-order conversion of a single reactant to a product. This likely results from cognitive difficulties in combining structural, chemical, mathematical, and textual descriptions of binding and catalytic reactions. To help students better understand dynamic reactions and their analyses, we have introduced two kinds of interactive graphs and simulations into the online educational resource, Fundamentals of Biochemistry, a LibreText biochemistry book. One is available for simple binding and kinetic reactions. The other displays progress curves (concentrations vs. time) for simple reactions and complex metabolic and signal transduction pathways. Users can move sliders to change dissociation and kinetic constants as well as initial concentrations and see instantaneous changes in the graphs. They can also export data into a spreadsheet for further processing, such as producing derivative Lineweaver-Burk and traditional Michaelis-Menten graphs of initial velocity (v0) versus substrate concentration.

Spin-Enhanced C–C Coupling in CO 2 Electroreduction with Oxide-Derived Copper

Spin-Enhanced C–C Coupling in CO ₂ Electroreduction with Oxide-Derived Copper

First-Principles Study on the Impact of Stress on Depassivation of Defects at a-SiO2/Si Interfaces

The amorphous silicon dioxide-silicon (a-SiO2/Si) interface is an important part of silicon devices. It is difficult to avoid interface defects during the device production process. The passivated interface defects will undergo a depassivation reaction with the protons in the silicon dioxide generated by irradiation and convert to positively charged dangling bonds, thereby affecting device performance. In engineering practice, there is a final passivation layer on top of a-SiO2, and it is inevitable to introduce stress on the a-SiO2/Si interface. Therefore, studying the depassivation reaction mechanism of a-SiO2/Si interface defects under stress is of great significance to understand the performance degeneration in real devices. By using molecular dynamics and first-principles calculations, Pb defects at a-SiO2/Si (111) interface and Pb1 defects at a-SiO2/Si (100) interface are selected in this work to investigate the effect of stress on their depassivations. Biaxial strains are applied to the models, energy curves of the depassivation reactions under stress are calculated using the CI-NEB (Climbing Image Nudged Elastic Band) method, and transition states are identified. According to the Harmonic Transition State Theory (HTST), the reaction rate constants of the depassivation reactions of Pb and Pb1 defects at a certain temperature can be obtained. Finally, the relative concentration curves during depassivation reactions of PbH and Pb1H under stress and room temperature are obtained. Detailed data and figure analyses are presented to demonstrate differences between the two typical interface defects when depassivating under stress. Appropriate degrees of interface stress are proved to extend the depassivation time of defects, therefore prolonging the service life of devices.

The Nutritional Quality and Structural Analysis of Black Soldier Fly Larvae Flour before and after Defatting.

Simple SummaryThe increasing global population and consumer demand for protein will render the provision of protein a serious future challenge, thus placing substantial pressure on the food industry to provide for the human population. The lower environmental impact of insect farming makes the consumption of insects such as black soldier fly larvae (BSFL) an appealing solution, although consumers in developed countries often respond to the idea of eating insects with aversion. One approach to adapt consumers to insects as part of their diet is through the application of making insect-based products in an unrecognized form. Nutritional value and structural properties of the BSFL flours (full fat and defatted) were assessed. Defatted as well as full-fat flour both displayed good nutritional and structural characteristics for use in many food applications.This study aimed to assess the nutritional information and structural overview of the BSFL (black soldier fly larva) flours (full fat and defatted). The BSFL flours were obtained by freeze-drying the larvae and the removal of fat using hexane and isopropanol ratio of 3:2 (v/v), these solvents were used due to their defatting efficiency and because they are less toxic. Nutritional and structural analyses were conducted using standard methods. The full-fat and defatted flours had high protein content (45.82% and 56.11% respectively). Defatting significantly (p < 0.05) increases the protein content by approximately 10%, while the fat content decreased from 25.78% in full-fat larvae to 4.8% in defatted larvae. The compositional data were qualitatively confirmed with Universal Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (UATR-FTIR) mainly in the amide I and II regions. Thermal gravimetry (TG) and differential scanning calorimeter (DSC) analysis, showed the conformational physical changes induced due to removal of fat which affected protein denaturation. DSC analysis displayed curves of both endothermic and exothermic reactions. During the first heating program, both samples had wide endothermic heating peaks ranging from 42 to 112 °C, which may be attributed to the water content in the samples evaporating. The first stage of the decomposition process was important, with loss of free and loosely bound water up to 150 °C, according to TGA curves. Protein and carbohydrates volatilized during the second stage of decomposition. The third level may be linked to polypeptide decomposition. FTIR revealed that the defatting process induced structural modifications on the amide I (1650 cm−1) and amide II (1540 cm−1) regions. Defatting has a significant effect on the functional groups and nutritional value of the BSFL. Defatted as well as full-fat flour both show good nutritional and structural characteristics for use in many food applications, however the improved proximate composition of the defatted BSFL can be applied to food products using BSFL flour as an alternative ingredient.

SOLVING INVERSE PROBLEM OF CHEMICAL KINETICS WITH USE OF CUBIC SPLINES

A simple effective method for solving the inverse problem of chemical kinetics based on non-stationary experiments for multistage reactions occurring in an isothermal reactor of ideal mixing is described. The idea of the method is based on taking into account the distinctive features (informativeness) of different fragments of relaxation curves for chemical reactions with arbitrary (non-monotonic) kinetics and their as accurate approximation as possible. For this purpose, non-linear (cubic) splines are used to describe different informative fragments of relaxation curves, which allow to approximate and interpolate experimental data as accurately as possible. An additional advantage of cubic splines, from the point of view of the implementation of the described method, is their continuity at all given points up to and including second-order derivatives (smoothness). This allows us to calculate with good accuracy not only the concentration of reagents, but also the instantaneous rate of change at any time. The consequence of this is the possibility of a sufficiently accurate solution of the inverse problem based on the data of non-stationary experiments. The correctness of the mathematical model used and the stability of the method were tested using variations of the original data. An example of using the method for determining the intervals of physical values of the rate constants of the stages of a two-stage reaction is given. The influence of the method of selecting the reference points (structure) of the spline and measurement errors (noise) of experimental data on the error of determining the speed constants of the stages is estimated. The efficiency of application and good accuracy of the method for solving the inverse problem of chemical kinetics of multistage reactions occurring in non-gradient systems with taking into account of noise is shown.

Real-Time Fluorescence-Based Approaches to Disentangle Mechanisms of a Protein's RNA Chaperone Activity.

RNA-binding proteins with an RNA chaperone activity exert either one or both of the following catalytic activities: (1) RNA annealing, i.e., the protein supports intra- as well as intermolecular RNA-RNA interactions and (2) strand displacement, i.e., the protein mediates the exchange of individual strands of a preexisting RNA duplex. To discriminate and further characterize these activities, it requires defined assay systems. These are based on entirely or partially complementary RNA oligonucleotides that are labeled with fluorescent and/or quencher dyes. The non-catalyzed and the protein-supported associations of the RNA molecules are followed by a real-time fluorescence resonance energy transfer (FRET) system. By site-specific modification of the RNAs or the protein, the substrate- and protein-specific parameters of the RNA chaperone activity can be explored and identified.In this chapter, we present strategies on the design of labeled RNA molecules to be used to characterize the activities of an RNA-binding protein and explain how to monitor progress curves of RNA annealing and strand displacement reactions in single cuvette or well-plate scales. We provide sets of equations and models to determine and analyze different types of reactions, e.g., by calculation of first- and second-order rate constants. Likewise, we demonstrate how to exploit these simple experimental setups to elucidate elementary principles of the reaction mechanisms performed by the protein of interest by applying basic kinetic applications, such as ARRHENIUS and linear free energy relationship analyses. These approaches will be explained by providing example plots and graphs from experiments investigating the RNA chaperone activities of the RNA-binding proteins NF90-NF45 and AUF1 p45.

Microscopic Picture of the Solvent Reorganization During Electron Transfer to Flavin in Water.

The redox potential of molecular species is largely modulated by its molecular environment so that a change of the environment will lead to a different redox potential. However, a detailed molecular picture of reorganization of the environment upon reduction is still unclear. To unravel the details of the solvent reorganization during electron transfer, we have performed density functional theory-based molecular dynamics (DFT-MD) and hybrid quantum mechanics/molecular mechanics (QM/MM) simulations of the reduction of lumiflavin. Previously, we have calculated the reduction free energy curves of the redox half reactions of lumiflavin in water as a function of the instantaneous gap energy (ΔE) ( J. Chem. Theory Comput. 2013 , 9 , 3889 - 3899 ). In this work, we focus on finding the changes in the solvent environment that correlate with this ΔE reaction coordinate. Comparing the QM/MM simulations, in which the solvent is modeled with an empirical force field, with the (full) DFT-MD simulations, we find that the response through electronic polarization plays a significant role in the latter case. Also a small charge transfer between flavin and solvent is observed in the full DFT treatment. As a result, we find only in the case of the QM/MM model a strong correlation between ΔE and the (pairwise computed) electrostatic potential (ESP) at the flavin due to the solvent. By analyzing the contribution of the ESP at the flavin per solvent molecule, we cannot only distinguish between the different modes of hydration by solvent molecules that coordinate at the hydrophilic and hydrophobic sides of the flavin molecule but also quantify their contribution to the reorganization free energy by measuring the ESP fluctuations per solvent molecule.

Volcano curves for homologous series reactions: Oxidation of small alkanes

Volcano curves are typically developed and used for predicting new catalysts for a single reaction and one substrate. The concept of using the volcano curve to predict catalysts for an entire homologous series of reactions has been unexplored. Herein the catalytic activity of seven monometallic catalysts (Pt, Pd, Rh, Ag, Ni, Cu, and Co/Al2O3) and three Ag-Pd/Al2O3 bimetallic catalysts is evaluated in the total oxidation of small alkanes (methane, ethane, propane, and isobutane) in the 280–400 °C temperature range under fuel lean and rich conditions. We show that hysteresis in activity, with three distinct kinetic regimes, is a common phenomenon of alkane oxidation over all catalysts studied when varying the oxygen concentration, and the size of the hysteresis loop depends on the oxophilicity of the catalyst and the reducing ability of the hydrocarbon. Expectedly, the concept of the universality of the volcano curve for a homologous series is valid but only when a suitable surrogate substrate is chosen. Hydrocarbons with two or more carbon atoms can serve as surrogates of the alkane homologous series, whereas methane is not. Interestingly and consistent with the hysteresis, the feed composition controls the catalyst oxidation state and potentially impacts the optimal catalyst descriptors used to determine new catalysts. The predicted 1:3 Ag-Pd catalyst is indeed superior to single metals for the homologous series under fuel lean conditions for ethane and larger alkanes. It is inferior to Pt under fuel rich conditions and better than Pd and Pt for methane rich conditions. A method for qualitative inference of the catalyst structure, based on the volcano curve and the oxidation state of the catalyst, is proposed.

Simulation and Fitting of Cyclic Voltammetry and Chronoamperometry Curves of Electrochemical Reactions with Different Mechanisms — A Didactic Perspective

Electrochemical simulations are presented to introduce students to the capabilities of cyclic voltammetry (CV). The systems chosen involve one and two-electron transfers, and can be delineated with CV as being reversible, quasi-reversible, or irreversible. The rate constants for the electron transfer can be estimated by the theory of Nicholson and Shain. DigiElch, professional® provides the opportunity of fitting experimental CVs after assuming a reaction scheme. We will demonstrate data fitting for two different mechanisms, electron transfer E and electron transfer followed by a chemical reaction with a subsequent electron transfer of the product ECE.

New intelligent photometric titration system and its method for constructing chemical oxygen demand based on micro-flow injection

The characteristics of the signals during the process of chemical oxygen demand (COD) titration are analyzed in this paper. The signals are derived for normalized titration curves of reactions having the color mutation reaction. After analyzing the characteristics, the critical control points are observed. The switch, stop and end points are searched by the algorithm on a computer. Based on this three-point method, a new intelligent photometric titration system is constructed for COD, without using the calibration curves. Using this system, a new intelligent photometric titrator has been built for COD for automatic sampling and intelligent titrating. Under computer control, the process of titration is conducted intelligently and accurately; no manual operation or assistance is required. The titration chamber was homemade. The optimized conditions of the titration system are as follows: the titrant was consecutively micro-flow injected into the chamber with a velocity of 0.00576 mL·s−1; 100 points per second of the titrating process signal were collected; and the homemade agitator blade stirred at a speed of 420 rpm. The preferences tested by actual samples proved that this titrator meets the requirements of the standard method and is suitable for use in experiments. Overall, our approach facilitates adoption of an intelligent titrimetry system for the determination of photometric titration.

(Invited) Influence of the Crystal Structure of Manganese Oxides on the ORR Kinetics: A Combined Experimental and Computational Study

Recently, while studying the oxygen reduction reaction (ORR) in alkaline medium on Mn oxides with various crystal structures, we documented [1] an unparalleled activity of Mn2O3 oxide with bixbyite structure. Then we also observed a clear correlation of the electrocatalytic activity with the formal potential of Mn(IV/III) interfacial redox transition and suggested the ORR mechanism involving this transition as a mediator step. To extend our understanding of this complex mechanism, we also compared the behavior of various oxides in peroxide oxidation/reduction reactions [2] and in respect to the peroxide yield during the ORR. All materials were studied in the form of composites with Sibunit carbon (weight ratio 1:1). This carbon binder provides a high utilization of the oxide surface in electrocatalysis [3]. The voltammetry in deairated 1M NaOH solution and rotating disc electrode (RDE) measurements in the same but O2-saturated solution were used to determine the total charge and the ORR kinetic currents. Rotating ring disc electrode (RRDE) was applied to compare the peroxide yields on various Mn oxides. All the values were compared after normalizing them to the BET surface area. The number of electrons involved in the oxygen reduction was close to 4 and 3 for more and less active oxides, respectively. Less active oxides demonstrated significantly higher peroxide yields and slower peroxide reduction, with a convection-independent limiting current which documents a slow chemical step in a wide potential region. The independent experimental facts which can be considered for comparison with simulations are as follows: surface concentration of the Mn active centers (estimated from the total charge in Mn(IV/III) transition region);specific activity of pure carbon generating additional peroxide, which further reacts on the oxide component in carbon-oxide composites (see in Ref.[4] about the dual role of carbon);ORR polarization curves;polarization curves for peroxide reactions;peroxide yield during the ORR. This wide set of data provides a valuable input for multi-parametric simulations, which significantly decreases the number of possible solutions. The modeling involved the rate constants for five reaction steps as well as the parameter for interactions of the adsorbed oxygen species involved in the Mn(IV/III) transition (in terms of Frumkin isotherm). We found that the complete set of data can be interpreted only assuming the structural dependence of at least two rate constants: one at the initial stage (peroxide formation) and another at the final stage (peroxide reduction). Another intriguing possibility to explain the very high Mn2O3 activity in the ORR is to assume a direct ORR pathway for this oxide, and to consider a series pathway for all other oxides. To elucidate whether the latter hypothesis is reasonable, we addressed the O-O bond break on Mn2O3 and MnOOH (typical examples of high and low activities, respectively) in the framework of a quantum chemical approach resting on the cluster model of the oxide surface and the DFT level of theory. The computational results were used to map the effective reaction path. We found that for both model surfaces the direct bond cleavage at the oxide surface is hardly feasable both for the O2 molecule and most likely for peroxide intermediates. This finding makes it possible to exclude the direct pathway and to focus on molecular reasons of the structural effects on the rate constant for other steps such as the reduction of the adsorbed peroxide intermediate. The work is supported by EraNetRus program, project (#270 NANO-Morf). [1] A.S. Ryabova et al, Electrochimica Acta 187 (2016) 161–172. [2] A.S. Ryabova et al, ChemElectroChem 3 (2016) 1667 – 1677. [3] A.S. Ryabova et al, Electrochimica Acta 246 (2017) 643–653. [4] T. Poux et al, Catalysis Today 189 (2012) 83– 92.

Calculation of productions of PET radioisotopes via phenomenological level density models

In the present paper, we have explained the phenomenological level density models to utilize it in the production of positron emission tomography (PET) radioisotopes. To achieve this aim, the cross-sections of reaction processes were calculated by TALYS code for the level density models. Additionally, to estimate the production of PET radioisotopes, the integral yield curves of reactions for three different level density models were calculated using the mass stopping power obtained from X-PMSP program in the particle beam current of 1 µA and irradiation time 1 h. Based on these results, we discussed the suitable level density model for the production of PET radioisotopes.

Dose–response curves for MRI-detected radiation-induced temporal lobe reactions in patients after proton and carbon ion therapy: Does the same RBE-weighted dose lead to the same biological effect?

PurposeTo derive the dose–response curve for temporal lobe reactions (TLRs) after proton therapy and to compare the resulting relative biological effectiveness (RBE)-weighted tolerance doses based on an RBE of 1.1 with published values for carbon ions, which were calculated by the two versions of the local effect model (LEM I or IV). Methods and materials62 patients treated with protons for skull base tumors were analyzed for TLRs using magnetic resonance imaging. Within the mean follow-up time of 38 months, TLRs were observed in six patients. Dose–response curves based on the RBE-weighted maximum dose, excluding the 1 cm3-volume with the highest dose, were derived and compared to previously published dose–response curves for carbon ions, which were obtained using LEM I or IV, respectively. ResultsThe dose–response curves for protons and LEM I were found to be almost identical while the curve of LEM IV was shifted toward higher doses. The resulting tolerance doses at the 5% effect level were 68.2+2.7-5.6, 68.6+3.0-3.9 and 78.3+3.8-5.0 Gy (RBE), respectively. ConclusionsThe RBE-weighted dose prescription for protons leads to the same RBE-weighted dose–response curve for TLR as the one for LEM I-based carbon ions, while LEM IV predicts clinically significant higher tolerance doses.

Thermodynamic Activity-Based Progress Curve Analysis in Enzyme Kinetics

Macrokinetic Michaelis-Menten models based on thermodynamic activity provide insights into enzyme kinetics because they separate substrate-enzyme from substrate-solvent interactions. Kinetic parameters are estimated from experimental progress curves of enzyme-catalyzed reactions. Three pitfalls are discussed: deviations between thermodynamic and concentration-based models, product effects on the substrate activity coefficient, and product inhibition.

Dual kinetic curves in reversible electrochemical systems

We introduce dual kinetic chronoamperometry, in which reciprocal relations are established between the kinetic curves of electrochemical reactions that start from symmetrical initial conditions. We have performed numerical and experimental studies in which the kinetic curves of the electron-transfer processes are analyzed for a reversible first order reaction. Experimental tests were done with the ferrocyanide/ferricyanide system in which the concentrations of each component could be measured separately using the platinum disk/gold ring electrode. It is shown that the proper ratio of the transient kinetic curves obtained from cathodic and anodic mass transfer limited regions give thermodynamic time invariances related to the reaction quotient of the bulk concentrations. Therefore, thermodynamic time invariances can be observed at any time using the dual kinetic curves for reversible reactions. The technique provides a unique possibility to extract the non-steady state trajectory starting from one initial condition based only on the equilibrium constant and the trajectory which starts from the symmetrical initial condition. The results could impact battery technology by predicting the concentrations and currents of the underlying non-steady state processes in a wide domain from thermodynamic principles and limited kinetic information.

Applications of the SW96 formulation in the thermodynamic calculation of fluid inclusions and mineral-fluid equilibria

The SW96 formulation explicit in Helmholtz free energy proposed by Span and Wagner (1996) is the most accurate multifunction equation of state of CO2 fluid, from which all thermodynamic properties can be obtained over a wide temperature-pressure range from 216.592 to 1100 K and from 0 to 8000 bar with or close to experimental accuracy. This paper reports the applications of the SW96 formulation in fluid inclusions and mineral-fluid equilibria. A reliable and highly efficient algorithm is presented for the saturated properties of CO2 so that the formulation can be conveniently applied in the study of fluid inclusions, such as calculation of homogenization pressures, homogenization densities (or molar volumes), volume fractions of vapor phase and isochores. Meanwhile, the univariant curves of some typical decarbonation reactions of minerals are calculated with the SW96 formulation and relevant thermodynamic models of minerals. The computer code of the SW96 formulation can be obtained from the corresponding author.

Reduction of Carbon Dioxide by a Molybdenum-Containing Formate Dehydrogenase: A Kinetic and Mechanistic Study.

Carbon dioxide accumulation is a major concern for the ecosystems, but its abundance and low cost make it an interesting source for the production of chemical feedstocks and fuels. However, the thermodynamic and kinetic stability of the carbon dioxide molecule makes its activation a challenging task. Studying the chemistry used by nature to functionalize carbon dioxide should be helpful for the development of new efficient (bio)catalysts for atmospheric carbon dioxide utilization. In this work, the ability of Desulfovibrio desulfuricans formate dehydrogenase (Dd FDH) to reduce carbon dioxide was kinetically and mechanistically characterized. The Dd FDH is suggested to be purified in an inactive form that has to be activated through a reduction-dependent mechanism. A kinetic model of a hysteretic enzyme is proposed to interpret and predict the progress curves of the Dd FDH-catalyzed reactions (initial lag phase and subsequent faster phase). Once activated, Dd FDH is able to efficiently catalyze, not only the formate oxidation (kcat of 543 s(-1), Km of 57.1 μM), but also the carbon dioxide reduction (kcat of 46.6 s(-1), Km of 15.7 μM), in an overall reaction that is thermodynamically and kinetically reversible. Noteworthy, both Dd FDH-catalyzed formate oxidation and carbon dioxide reduction are completely inactivated by cyanide. Current FDH reaction mechanistic proposals are discussed and a different mechanism is here suggested: formate oxidation and carbon dioxide reduction are proposed to proceed through hydride transfer and the sulfo group of the oxidized and reduced molybdenum center, Mo(6+)═S and Mo(4+)-SH, are suggested to be the direct hydride acceptor and donor, respectively.

Transport Properties Study on Carbon Electrodes for Vanadium Redox Flow Batteries

The electrode is a key component to optimize in the vanadium redox flow battery (VRFB) to achieve high battery performance and market competitiveness. Generally, carbon based materials are the most prevalent type of electrode utilized in commercial and experimental VRFBs.1 Fibrous carbon materials and their derivatives are widely used as electrodes in VRFB system because they are porous to allow electrolyte penetration, resistant to the electrolyte chemical environment and relatively low-cost. Recently, significant performance improvement of VRFB has been achieved by utilization of carbon paper materials with enhanced surface properties.2 Mass transport is a major factor in the efficiency loss in VRFB, particularly at low states of charge. Ohmic, activation and mass transport overpotential losses cause efficiency loss in an electrochemical system.3The electrode loss is mainly comprised of activation and mass transport losses, while the ohmic loss is mainly due to separator resistance. The activation overpotential is caused by limited reaction rate of redox couple and limited surface area. The mass transport overpotential is caused by reaction active species depletion due to insufficient active species supply on electrode surface. Because of the slow motion of cation in solution, it is critical to understand the relationship between the electrode properties and mass transport in electrode. Future material development and system optimization can benefit from this work. The properties of the carbon electrode can have a strong influence on the active species mass transport inside the cell. In Figure 1, the IR corrected polarization curves of positive and negative redox reactions on SGL 10AA and X-2 in VRFB are shown at varying electrolyte flow rates. The electrode materials were housed in a 5 cm2 battery hardware (Fuel Cell Technologies Inc.) with serpentine flow field. The electrolyte was composed of 1.7 M vanadium ions with 5 M total sulfate/bisulfate. The state of charge was maintained at 55% during the entire polarization curve measurement. In both reactions, the polarization curves show a typical mass transport limiting current density (iMT ) at high overpotential. In both reactions, higher iMT on 10AA indicates the better mass transport towards the surface of 10AA in the experimental scenario. X-2 is advantageous in reaction kinetics, since the activation overpotential is always lower on X-2 than 10AA in both reactions. However, the current density on 10AA generally surpasses that of X-2 at elevated overpotential. This trend should be attributed to better mass transport property of 10AA, though the detailed mechanism is not clear yet. We will present a thorough study of the mass transport properties of carbon paper electrode in VRFB cell. A systematic study of the physical properties and their influence on the convective and diffusive transport of redox active species within the electrode will be discussed. The transport study will be correlated to electrochemical test to develop a protocol to evaluate the mass transport properties’ influence on battery’s performance. This work is supported by Dr. Imre Gyuk, Office of Electricity Delivery and Energy Reliability, US Department of Energy. Reference: 1. M. H. Chakrabarti, N. P. Brandon, S. A. Hajimolana, F. Tariq, V. Yufit, M. A. Hashim, M. A. Hussain, C. T. J. Low, and P. V. Aravind, J. Power Sources, 253, 150–166 (2014) 2. A. M. Pezeshki, J. T. Clement, G. M. Veith, T. A. Zawodzinski, and M. M. Mench, J. Power Sources, 294, 333–338 (2015) 3. D. S. Aaron, Z. Tang, A. B. Papandrew, and T. A. Zawodzinski, J. Appl. Electrochem., 41, 1175–1182 (2011). Figure 1. IR corrected discharging polarization curves of negative and positive redox couple on SGL 10AA and X-2 in 5 cm2 FCT flow battery cell of varying flow rates with 1.7 M V2/3+/5 M bisulfate/sulfate electrolyte at 55% SoC. Figure 1

New Method for Extracting Diffusion-Controlled Kinetics from Differential Scanning Calorimetry: Application to Energetic Nanostructures

A new expression is derived for interpreting differential scanning calorimetry curves for solid-state reactions with diffusion-controlled kinetics. The new form yields an analytic expression for temperature at the maximum peak height that is similar to a Kissinger analysis, but that explicitly accounts for laminar, cylindrical, and spherical multilayer system geometries. This expression was used to analyze two reactive multilayer nanolaminate systems, a Zr/CuO thermite and an Ni/Al aluminide, that include systematically varied layer thicknesses. This new analysis scales differential scanning calorimetry (DSC) peak temperatures against sample geometry, which leads to geometry-independent inherent activation energies and prefactors. For the Zr/CuO system, the DSC data scale with the square of the bilayer thickness, while, for the Ni/Al system, the DSC data scale with the thickness. This suggests distinct reaction mechanisms between these systems.

Kinetics of steam gasification of bituminous coals in terms of their use for underground coal gasification

The kinetics of steam gasification was examined for bituminous coals of a low coal rank. The examined coals can be the raw material for underground coal gasification. Measurements were carried out under isothermal conditions at a high pressure of 4MPa and temperatures of 800, 900, 950, and 1000°C. Yields of gasification products such as carbon monoxide and carbon dioxide, hydrogen and methane were calculated based on the kinetic curves of formation reactions of these products. Also carbon conversion degrees are presented. Moreover, calculations were made of the kinetic parameters of carbon monoxide and hydrogen formation reaction in the coal gasification process. The parameters obtained during the examinations enable a preliminary assessment of coal for the process of underground coal gasification.