Concentrations Of Reaction Products Research Articles

Employing generative adversarial neural networks as surrogate model for reactive transport modeling in the hyporheic zone

This study explores the application of advanced deep learning techniques, specifically conditional deep convolutional generative adversarial networks (cDC-GANs), to model and predict the complex dynamics of the hyporheic zone (HZ) driven by river stage fluctuations. The HZ is a critical transitional mixing zone between surface water and groundwater, where significant biogeochemical reactions occur. Traditional process-based reactive transport modeling methods are computationally intensive and require fine-scale parameterization. To overcome these challenges, we employ the cDC-GAN as a deep-learning-based surrogate model to predict zones of enhanced biogeochemical activity (i.e., hotspots) and reaction product concentrations in the HZ under varying bimodal sedimentary heterogeneity scenarios. The cDC-GAN model can efficiently capture nonlinear relationships between input data and output parameters without extensive parameterization, making it computationally less demanding. The model’s generative capabilities allow for the creation of new data instances, enabling the exploration of diverse scenarios and interpolation between observed data points. The model uses maps of liquid saturation and solute concentrations at different time steps to generate corresponding maps of reaction rates and reaction product concentrations. Results demonstrate the model’s qualitative and quantitative ability to capture complex relationships without relying on rigid assumptions about linearity or specific probability distribution functions. Notably, even amid variations in aquifer heterogeneity, the model consistently exhibits robust performance, validating its ability to adapt to dynamic geological settings. Our use of a simplified reaction scheme serves as a proof of concept for the cDC-GAN model’s ability to simulate solute transport in the HZ, opening avenues for future applications including more complex reaction networks within HZ system such as nutrient cycling, organic matter degradation, redox reactions, and beyond.

Incorporating different enzyme kinetics in amperometric biosensor for the steady-state conditions: A complete theoretical and numerical approach

The well-defined physical, chemical, and biological interactions that define the behaviour of biosensors are described by nonlinear differential equations. Because these biosensors have so many uses in many domains, it is desirable to represent them mathematically. The enzyme kinetic and the diffusion rate across the enzymatic layer determine the distinct enzymatic processes. The biosensors are modelled by a system of reaction-diffusion equations involving a nonlinear part associated with the reaction rate. The nonlinear equations in this model have been solved analytically (Rajendran-Joy method) and numerically (MATLAB® v2016b software). Approximate steady-state analytical solutions for the substrate and reaction product concentrations and the output current are presented for specific cases of first-order, Michaelis-Menten and ping-pong kinetics. The influence of various parameters on concentrations and currents is discussed. Further, the sensitivity of parameters in current was also analysed. The analytical results are compared with numerically simulated results for various kinetics.

Elementary Reaction Steps That Precede or Follow a Unimolecular Reaction Step Can Obfuscate Interpretation of the Driving-Force Dependence to Its Rate Constant.

Assessing the validity of a driving-force-dependent kinetic theory for a unimolecular elementary reaction step is difficult when the observed reaction rate is strongly influenced by properties of the preceding or following elementary reaction step. A well-known example occurs for bimolecular reactions with weak orbital overlap, such as outer-sphere electron transfer, where bimolecular collisional encounters that precede a fast unimolecular electron-transfer step can limit the observed rate. A lesser-appreciated example occurs for bimolecular reactions with stronger orbital overlap, including many proton-transfer reactions, where equilibration of an endergonic unimolecular proton-transfer step results in a relatively small concentration of reaction products, thus slowing the rate of the following step such that it becomes rate limiting. Incomplete consideration of these points has led to discrepancies in interpretation of data from the literature. Our reanalysis of these data suggests that proton-transfer elementary reaction steps have a nonzero intrinsic free energy barrier, implying, in the parlance of Marcus theory, that there is non-negligible nuclear reorganization. Outcomes from our analyses are generalizable to inner-sphere electron-transfer reactions such as those involved in (photo)electrochemical fuel-forming reactions.

Reverse water gas-shift reaction product driven dynamic activation of molybdenum nitride catalyst surface

In heterogeneous catalysis catalyst activation is often observed during the reaction process, which is mostly attributed to the induction by reactants. In this work we report that surface structure of molybdenum nitride (MoNx) catalyst exhibits a high dependency on the partial pressure or concentration of reaction products i.e., CO and H2O in reverse water gas-shift reaction (RWGS) (CO2:H2 = 1:3) but not reactants of CO2 and H2. Molybdenum oxide (MoOx) overlayers formed by oxidation with H2O are observed at reaction pressure below 10 mbar or with low partial pressure of CO/H2O products, while CO-induced surface carbonization happens at reaction pressure above 100 mbar and with high partial pressure of CO/H2O products. The reaction products induce restructuring of MoNx surface into more active molybdenum carbide (MoCx) to increase the reaction rate and make for higher partial pressure CO, which in turn promote further surface carbonization of MoNx. We refer to this as the positive feedback between catalytic activity and catalyst activation in RWGS, which should be widely present in heterogeneous catalysis.

The role of supplementary cementitious materials and fiber reinforcements in enhancing the sulfate attack resistance of SCC/ECC composite systems

The purpose of this study is to investigate the effects of sulfate exposure on the mechanical behavior of fresh-to-fresh composite systems (CS), incorporating self-compacting concrete (SCC) in compression and engineered cementitious composites (ECC) in tension. ECCs were designed based on various supplementary cementitious materials (SCM) such as low and high calcium fly ash, slag and reinforcing fibers such as PVA and steel fibers. Repeated cycles of immersion in concentrated sodium sulfate solution were followed by drying at high temperatures (80 °C). After 90 and 180 days of cyclic exposure, the mechanical properties including flexural, compressive and tensile bond strength and mass change were evaluated. To investigate microstructural deterioration and reaction product concentration, SEM-EDS and backscattered electron imaging were used to examine sulfate profiles at the interfacial zone between SCC and ECC. Composite samples demonstrated excellent physico-mechanical resilience. The incorporation of low calcium fly ash and slag was observed to have a beneficial impact on residual mechanical properties in long-term exposures, along with the de-passivation capacity of the reinforcing fibers. No physical de-bonding was observed in any CS, however phase assemblages revealed high concentrations of reaction products in the SCC layers near the interfacial bond with the ECC layers.

Nonlinear effects of partitioning and diffusion-limiting phenomena on the response and sensitivity of three-layer amperometric biosensors

The influence of the partitioning and diffusion limitations on the response of amperometric biosensors is investigated analytically and computationally using a three-compartment model: an enzyme layer, a diffusion limiting membrane and an outer diffusion layer. The biosensors are modelled by a system of reaction–diffusion equations involving a nonlinear term related to Michaelis–Menten kinetics. Exact steady state analytical solutions for the substrate and reaction product concentrations and the output current are presented for specific cases of first and zero-order reaction rates. The performance of the biosensor is numerically investigated at the transition conditions. Application of different specific types of the interface conditions, perfect contact and partition conditions, at which the steady state biosensor response is the same for both types of the interface conditions is analysed. The effective diffusion coefficients merging two diffusion layers are defined for reducing the three-compartment to the corresponding two-compartment model. The nonlinear and non-monotonic behaviour of the biosensor response is discussed.

High-precision finishing method for narrow-groove channel-cut crystal x-ray monochromator using plasma chemical vaporization machining with wire electrode.

A channel-cut crystal monochromator (CCM) is a popular and powerful device for producing monochromatic x-ray beams with extreme angular stability at a nano-radian level. Narrowing the groove width of CCMs has various benefits; for example, it is made possible to design more compact CCMs with an equivalent working energy range and to reduce the optical delay and the amount of beam shift, enhancing compatibility with various experimental techniques. An obstacle to the use of narrow-groove CCMs is the lack of a high-precision finishing method for the inner-wall reflecting surfaces, which imposes the distortion of x-ray wavefronts and spectral purity. We propose a new, damage-free surface-finishing method for silicon CCMs with a narrow groove of 1mm or less with a localized etching technique using plasma generated with a wire electrode of 50 µm diameter under atmospheric pressure. Repeating plasma-on and plasma-off periods with a pulsed power supply, we reduce the concentration of reaction products through self-diffusion during the plasma-off periods and minimize the redeposition of the products on the processed surface that deteriorates the surface roughness. Under optimized conditions, we processed a CCM with a groove width of 1.2mm, which has uniform reflection profiles and a nearly ideal reflectivity behavior for coherent monochromatic x rays.

Thermal reaction products and formation pathways of two monoterpenes under in situ thermal desorption conditions that mimic vaping coil temperatures

Vaping has become more popular and different brands and types of vaping devices have rapidly emerged. However, little is known about the potential health risks of human inhalation exposures to the volatile chemicals in the vapour, which includes both directly vaporised components of vaping liquid and their reaction products formed during vaping processes. This study investigated reaction products of two monoterpenes (α-pinene and terpinolene) that are used as flavouring agents in vaping liquids with a focus on the identification of reaction products and their formation pathways. The thermal desorption was conducted under an in situ condition that is in the range of heating coil temperature in vaping by thermally desorbing the chemicals at a temperature range of 100–300 °C. Additional clean air was introduced during the thermal desorption. 36 and 29 reaction products were identified from α-pinene and terpinolene, respectively, at a relative concentration of 0.01% and greater in the desorbed mixture. 3-Carene was the dominant reaction product of α-pinene, while reaction products of terpinolene was dominated by p-isopropenyltoluene. Several reaction pathways including ring opening, allylic oxidation, cyclo-etherification, Wagner–Meerwein rearrangement, epoxidation, cleavage and removal of partial structure, and dehydration were involved in the formation of various reaction products. These pathways and resulting relative concentrations of residual parent compound and reaction products were influenced by both temperature and amount of air present during thermal desorption. The study results demonstrate possible existence of reaction products from thermally labile chemicals like monoterpenes in vaping aerosols and can help inform policies regulating vaping devices and products to protect public health.

Non-thermal plasma treatment of sludge and its model compounds: Gasification characteristics and reaction kinetics

Plasma gasification stands as an effective technique for sludge treatment. This study focuses on investigating the characteristics of plasma sludge gasification using a plate barrier discharge reaction and examines both the sludge itself and its model compounds, glucose and leucine. A thorough analysis of voltage effects was conducted, and kinetic parameters for H2, CH4, and CO production were calculated. The findings revealed that increasing voltage led to higher concentrations of reaction products, with H2 being the predominate gas produced. Notably, glucose in the sludge contributed to CO2 production during the gasification reaction, while leucine played a vital role in enhancing H2 production. FTIR results showed that the initial step of the reaction primarily involved macromolecular ring-opening, followed by the secondary fracture of organic components, such as aromatic rings. Remarkably, the activation energy for sludge gasification under plasma was significantly lower (17.1 kJ/mol) compared to pyrolysis (above 70 kJ/mol).

An Artificial Liposome Compartment with Size Exclusion Molecular Transport.

The cellular compartment plays an essential role in organizing the complex and diverse biochemical reactions within the cell. By mimicking the function of such cellular compartments, the challenge of constructing artificial compartments has been taken up to develop new biochemical tools for efficient material production and diagnostics. The important features required for the artificial compartment are that it isolates the interior from the external environment and is further functionalized to control the transport of target chemicals to regulate the interior concentration of both substrate and reaction products. In this study, an artificial compartment with size-selective molecular transport function was constructed by using a DNA origami-guided liposome prepared by modifying the method reported by Perrault et al. This completely isolates the liposome interior, including the DNA origami skeleton, from the external environment and allows the assembly of a defined number of molecules of interest inside and/or outside the compartment. By incorporating a bacterial membrane protein, OmpF, into the liposome, the resulting artificial compartment was shown to transport only the molecule of interest with a molecular weight below 600 Da from the external environment into the interior of the compartment.

Effect of severe sulfate exposure on the bonding behavior of hybrid engineered composite systems

This article examines the sulfate resistance of composite concrete systems (CS) combining self-consolidating concrete (SCC) in compression and engineered cementitious composite (ECC) in tension, with special focus on the bonding properties at SCC/ECC interface. The effect of different fibers in the ECC tension area was investigated considering the use of PVA, steel and hybrid PVA/steel fibers at the same content. SCC and ECC layers were hot-jointed at fresh-to- fresh state and the hardened systems were tested under repeated cycles of concentrated sodium sulfate immersion and oven drying at a high temperature of 80 °C. Samples were assessed for physical, mechanical, and microstructural changes, including visual state, failure mode, mass, compressive strength, flexural properties and tensile bond strengths at different immersion-drying cycles. In addition, using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS) and backscattered electron imaging, sulfate profiles and phase assemblage methods were applied to investigate the concentration of reaction products of each SCC/ECC system. The long-term exposure results confirmed the advanced sulfate resistance of all CSs as compared to monolithic SCC. Considering the different degradation levels of CSs, the use of PVA demonstrated slightly enhanced physic-o-mechanical properties due to its greater interfacial effect at the SCC/ECC bond. Microstructural studies revealed that there were high concentrations of reaction products in the SCC layers that also affected a limited area near the interfacial bond with the ECC layers, particularly when steel fibers were included in CSs.

Multiphysics modeling of subcritical crack growth in glass

Subcritical crack growth starting from flaws on glass surfaces/edges causes slow degradation in glass strength. This phenomenon involves multiple physics and is very challenging to predict. In this work, we introduce a novel multiphysics model for subcritical crack growth in glass. This model considers water-assisted stress relaxation, stress-dependent chemical reaction between water and glass, diffusion of water to the crack tip, and reaction-driven slow crack growth. Stress relaxation is achieved by using a Prony series in the bond-based peridynamic viscoelastic model, and a new bond breakage criterion based on the concentration of reaction product is introduced. A displacement-loaded double beam with a pre-crack is used to obtain the crack velocity vs. stress intensity factor (v-K) curve. With proper simplifications and assumptions, v-K curves obtained from the model successfully reproduced their typical patterns in experiments. This model will help us better understand fundamental mechanisms and make predictions for subcritical crack growth in glass.

Application of a nucleophilic substitution reaction for spectrofluorimetric determination of aripiprazole in pharmaceutical dosage form and plasma matrix; greenness assessment

Aripiprazole is an antipsychotic medicine used to treat a variety of mental disorders, including irritability linked with autism disorder in children. Herein, a green and highly sensitive spectrofluorimetric method was developed for the determination of aripiprazole in pharmaceutical dosage form and plasma matrix. The method based on the formation of a fluorescent adduct from the nucleophilic substitution reaction of 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-chloride) with aripiprazole, which can be detected at 542 nm following excitation at 481 nm. Factors that affect the development and fluorescence sensitivity of the reaction product were investigated and optimized. The reaction yielded the most optimal fluorescence responses when it was performed using 1.5 mL of 0.2 % w/v NBD-chloride, 1.5 mL of borate buffer pH 9, heating at 80 °C for 20 min, and ethanol as a diluting solvent. The method was validated as per ICH guidelines for analytical and bioanalytical procedures. Good linearity was established between the fluorescence responses of the reaction product and aripiprazole concentrations in the range of 100–1200 ng/mL with adequate accuracy and precision results. The applied method was very sensitive and selectively determined aripiprazole in pharmaceutical and plasma matrices with no interferences. Furthermore, the compliance of the proposed method with the principles of green analytical chemistry was evaluated in comparison with the reported method using analytical eco-scale and AGREE metrics. The outputs proved that the proposed method complied more with the principles of green analytical chemistry than the reported method.

Reservoir characterization by push-pull tests employing kinetic interface sensitive tracers - a pore-scale study for understanding large-scale processes

The kinetic interface-sensitive (KIS) tracer experiment is a newly developed method to quantify the fluid-fluid interfacial area (FIFA) during drainage processes. The concentration breakthrough curves, obtained by measuring reaction product concentration in brine/water samples after breakthrough, are interpreted with a specialized numerical model to determine the FIFA. However, this method has its own limitations since the volume of the usable water sample (after breakthrough), based on which the analysis takes place, is often insufficient. This happens because this volume strongly depends on the aquifer material, i.e. sand type and system parameters. An alternative is to employ KIS tracers in a “push-pull” experimental set-up, i.e. primary drainage is followed by a consequent main imbibition process, with the flow direction being reversed. This study applies a pore-scale numerical model to study the KIS tracer reactive transport during a push-pull experiment in a 2D porous medium. The advective-dispersive-reactive transport during both primary drainage and main imbibition processes is discussed. The concentration breakthrough curves show a non-linear descending trend with time, until reaching a constant concentration at the steady state. By analyzing the spatial concentration distribution and the concentration breakthrough curve, the macro-scale KIS tracer reactive transport model can be interpreted for the push-pull process. Finally, the new method is applied in a column experiment, where the determined specific interfacial area is found to be close to literature data.

Formation of Maillard Reaction Products in Aged Sorghum Vinegar during Ageing and Protective Effects of Pure Vinegar Melanoidin Against CCl4-Induced Rat Hepatic Damage.

The processing method generally affects the toxicity and biological activity of aged sorghum vinegar. This study investigates the changes in the intermediate Maillard reaction products of sorghum vinegar during ageing and the in vivo hepatoprotective effects of pure melanoidin obtained from it. High-performance liquid chromatography (HPLC) and fluorescence spectrophotometry were utilized to quantify intermediate Maillard reaction products. The CCl4-induced liver damage in rats was used to evaluate the protective role of pure melanoidin in rat liver. Compared with the initial concentration, the 18-month ageing process caused a 1.2- to 3.3-fold increase in the concentrations of intermediate Maillard reaction products, i.e. 5-hydroxymethylfurfural (HMF), 5-methylfurfural (MF), methyglyoxal (MGO), glyoxal (GO) and advanced glycation end products (AGEs). The concentrations of HMF in the aged sorghum vinegar were 6.1-fold higher than the 450 μM limit standard for honey, implying the need for shortening the ageing of the vinegar in practice for safety concerns. Pure melanoidin (Mr>3.5 kDa) demonstrated significant protective effects against CCl4-induced rat liver damage, as evidenced by normalized serum biochemical parameters (transaminases and total bilirubin), suppressing hepatic lipid peroxidation and reactive oxygen species, as well as increasing glutathione amount and restoring antioxidant enzyme activities. Histopathological analysis revealed that melanoidin in vinegar reduced cell infiltration and vacuolar hepatocyte necrosis in rat liver. The findings demonstrated that a shortened ageing process should be considered in practice to ensure the safety of aged sorghum vinegar. Vinegar melanoidin is a potential alternative for the prevention of hepatic oxidative damage. This study demonstrates that the manufacturing process had a profound influence on the generation of vinegar intermediate Maillard reaction products. In particular, it revealed the in vivo hepatoprotective effect of pure melanoidin from aged sorghum vinegar, and provides insight into the in vivo biological activity of melanoidin.

Nanocellulose coated paper diagnostic to measure glucose concentration in human blood.

A new generation of rapid, easy to use and robust colorimetric point of care (POC) nanocellulose coated-paper sensors to measure glucose concentration in blood is presented in this study. The cellulose gel containing the enzyme with co-additive is coated and dried onto a paper substrate. Nanocellulose gel is used to store, immobilize and stabilize enzymes within its structure to prolong enzyme function and enhance its availability. Here, we immobilize glucose oxidase within the gel structure to produce a simple colorimetric blood glucose sensor. Increase in blood glucose concentration increases the concentration of reaction product which decreases the system pH detected by the pH indicative dye entrapped in the nanocellulose gel. The sensor produces a color change from red to orange as pH decreases due to the enzymatic reaction of glucose into gluconic acid and hydrogen peroxide. This sensor can measure glucose concentrations of 7-13mM (medical range for diabetes control) at temperatures of 4°C-40°C. Stability tests confirm that no denaturation of enzyme occurs by measuring enzyme activity after 4weeks. A prototype device is designed to instantly measure the glucose concentration from blood in a two steps process: 1) red blood cell separation and 2) quantification of glucose by color change. This study demonstrates nanocellulose sensor as an economical, robust, and sensitive diagnostic technology platform for a broad spectrum of diseases.

Nutrient and Maillard reaction product concentrations of commercially available pet foods and treats.

Thermal processing is used to produce most commercial pet foods and treats to improve safety, shelf life, nutritional characteristics, texture, and nutrient digestibility. However, heat treatments can degrade protein quality by damaging essential amino acids, as well as contribute to the Maillard reaction. The Maillard reaction forms melanoidins that favorably improve food qualities (e.g., color, flavor, aroma), but also form Maillard reaction products (MRP) and advanced glycation end-products that may negatively affect health. Because commercial pet diets are frequently fed to domestic cats and dogs throughout their lifetimes, it is critical to quantify MRP concentrations and understand the variables that influence their formation so future diets may be formulated with that in mind. Because few research studies on MRP in pet diets have been conducted, the goals of this study were to measure the MRP in commercial pet foods and treats, estimate pet MRP intake, and correlate MRP with dietary macronutrient concentrations. Fifty-three dry and wet dog foods, dog treats, and cat foods were analyzed for dry matter, organic matter, crude protein, acid-hydrolyzed fat, total dietary fiber, and gross energy using standard techniques. MRP were analyzed using high-performance liquid chromatography and gas chromatography-mass spectrometry. Data were analyzed using the Mixed Models procedure of SAS 9.4. Dry foods had lower reactive lysine concentrations and reactive lysine: total lysine ratios (indicator of damage) than wet foods. Wet foods had more fructoselysine (FRUC) than dry foods; however, dry dog treats contained more FRUC than wet dog treats. The greatest 5-hydroxymethyl-2-furfural (HMF) concentrations were measured in dry and wet dog foods, whereas the lowest HMF concentrations were measured in dry and wet cat foods. Based on dietary concentrations and estimated food intakes, dogs and cats fed wet foods are more likely to consume higher carboxymethyllysine and FRUC concentrations than those fed dry foods. However, dogs fed wet foods are more likely to consume higher HMF concentrations than those fed dry foods. In cats, those fed dry foods would consume higher HMF concentrations than those fed wet foods. We demonstrated that pet foods and treats contain highly variable MRP concentrations and depend on diet/treat type. In general, higher MRP concentrations were measured in wet pet foods and dry treats. While these findings are valuable, in vivo testing is needed to determine if and how MRP consumption affect pet health.

Spatially Resolved Deconvolution of Loss Processes in PEM Fuel Cells

The complex operating behaviour of PEM Fuel Cells is heavily influenced by different non-linear loss processes, which limit the cell performance. Depending on the operating conditions, the different losses change in magnitude and characteristic time constants [1]. During technical operation of large-sized PEM Fuel Cells, gradients in operating conditions occur along the gas channels, resulting in an inhomogeneous current density distribution. This is caused by the locally varying electrochemical activity due to in-plane gradients in concentrations of reactants and reaction products, gas pressure and temperature. Consequently, each loss process occurs locally distributed to a varying degree. Therefore, a profound knowledge about the spatial distribution of losses is essential for optimizing the operating strategy as well as the cell and stack components.The commonly measured I/V characteristics provide only integral information about the overall performance. Thus, the data obtained represent merely the sum of all loss processes averaged over the entire cell area and do not allow detailed conclusions about the respective spatial distribution along the channel.Inevitably, in order to deconvolute the loss processes in the entire area of large sized cells, an approach is required that provides deeper insight in the processes and their interdependencies. For this purpose, an impedance-based methodology is developed that enables a spatially resolved deconvolution of loss processes. It is based on electrochemical impedance spectroscopy (EIS) and an impedance data analysis by the distribution of relaxation times (DRT) [2,3] that is applied to a segmented cell [4] with almost gradient-free segments. By systematically varying operating conditions the different loss processes are identified, quantified and separated with respect to their characteristic frequencies.In this contribution the design of the test bench and the segmented cell will be presented. Furthermore, first results regarding the electrochemical characterization and the impedance-based deconvolution of loss processes in a segmented cell will be discussed. M. Heinzmann et al., J. Power Sources 402, pp. 24-33 (2018).H. Schichlein et al., J. Appl. Electrochem. 32, pp. 875-882 (2002).E. Ivers-Tiffée et al., J. Ceram. Soc. Japan 125, pp. 193-201 (2017).T. Reshetenko et al., J. Electrochem. Soc. 163, pp. F1100-F1106 (2016)

Influence of Oxygen Admixture on Plasma Nitrocarburizing Process and Monitoring of an Active Screen Plasma Treatment

The effect of a controlled oxygen admixture to a plasma nitrocarburizing process using active screen technology and an active screen made of carbon was investigated to control the carburizing potential within the plasma-assisted process. Laser absorption spectroscopy was used to determine the resulting process gas composition at different levels of oxygen admixture using O2 and CO2, respectively, as well as the long-term trends of the concentration of major reaction products over the duration of a material treatment of ARMCO® iron. The short-term studies of the resulting process gas composition, as a function of oxygen addition to the process feed gases N2 and H2, showed that a stepwise increase in oxygen addition led to the formation of oxygen-containing species, such as CO, CO2, and H2O, and to a significant decrease in the concentrations of hydrocarbons and HCN. Despite increased oxygen concentration within the process gas, no oxygen enrichment was observed in the compound layer of ARMCO® iron; however, the diffusion depth of nitrogen and carbon increased significantly. Increasing the local nitrogen concentration changed the stoichiometry of the ε-Fe3(N,C)1+x phase in the compound layer and opens up additional degrees of freedom for improved process control.

Reaction Products Affecting the PEFC Catalyst Ink Property

Catalyst ink is a key material of the catalyst layer in a proton exchange membrane fuel cell, but can be degraded as the reactions of alcohols are promoted by Pt in the ink. The present study quantitatively determined the concentrations of reaction products in an ethanol/water-based catalyst ink, and the effects of these substances on the ink and catalyst layer were investigated. The acetaldehyde concentration was found to be the key factor, as acetaldehyde caused particle agglomeration in the catalyst ink and micro-scale crack formation in the catalyst layer.