Change In Reaction Rate Research Articles

Strong coupling-induced frequency shifts of highly detuned photonic modes in multimode cavities.

Strong coupling between light and molecules is a fascinating topic exploring the implications of the hybridization of photonic and molecular states. For example, many recent experiments have explored the possibility that strong coupling of photonic and vibrational modes might modify chemical reaction rates. In these experiments, reactants are introduced into a planar cavity, and the vibrational mode of a chemical bond strongly couples to one of the many photonic modes supported by the cavity. Some experiments quantify reaction rates by tracking the spectral shift of higher-order cavity modes that are highly detuned from the vibrational mode of the reactant. Here, we show that the spectral position of these cavity modes, even though they are highly detuned, can still be influenced by strong coupling. We highlight the need to consider this strong coupling-induced frequency shift of cavity modes if one is to avoid underestimating cavity-induced reaction rate changes. We anticipate that our work will assist in the re-analysis of several high-profile results and has implications for the design of future strong coupling experiments.

Methods for Determining and Predicting Shelf Life of Food Products

The length of shelf life can be determined using storage tests that evaluate the physical, chemical, enzymatic, and microbiological stability of the food. The design of the tests as well as the interpretation of the results require microbiological and technical knowledge and skills. Fresh foods can become microbiologically risky before they noticeably spoil. These products will require additional studies such as predictive microbiological models or challenge tests in addition to direct ones. Deterioration of shelf-stable or frozen foods at the end of their shelf life affects quality and consumer acceptance without impacting health and safety. In such a case, accelerated shelf-life testing is recommended, and the Arrhenius model is commonly used to determine the relationship between chemical reaction rate and temperature change.

Spatial, Seasonal, and Diel Controls of Nitrogen‐Carbon‐Oxygen Cycling During Lake‐Water Infiltration to an Aquifer

AbstractMany freshwater lakes are groundwater flow‐through systems. Although lakes commonly are considered to be sinks for nitrogen inputs, relatively little is known about carbon and nitrogen export from lakes to groundwater. The current study focused on lake‐bottom biogeochemical processes accompanying the transport of nitrogen, dissolved oxygen (O2), and dissolved organic carbon (DOC) during lake‐water recharge from a groundwater flow‐through lake. Lake‐water and porewater (15–100 cm below lakebed) samples were collected along transects within the lake downwelling zone. Infiltrating porewater O2 and DOC concentrations decreased with depth while nitrate (NO3−) concentrations increased, indicating nitrification of organic matter within the profiles. The depth of NO3− production and transport was seasonally dependent. In winter, NO3− and O2 were exported beyond 100‐cm depth; whereas in summer, shallow nitrification zones were underlain by deeper NO3− reduction zones, and diel patterns of O2 and NO3− penetration depths were observed. Microbial community compositions and stable isotope profiles (δ15N[NO3−], δ18O[NO3−], δ18O[O2]) were consistent with apparent C–N–O reaction stoichiometries indicating O2 reduction and nitrification in shallower porewater, followed by varying NO3− reduction at depth. Maximum porewater NO3− concentrations (∼10–20 μM) were limited by infiltrating O2 concentrations and C/N ratios of reacting organic matter. Lake‐water level variations caused changes in shoreline position and porewater velocities, while variations in lake‐water temperature, DOC, and O2 contributed to changes in reaction rates and depth of O2 and NO3− penetration into the lakebed. The quality of groundwater recharged by lake water reflected temporally and spatially varying physical and biogeochemical processes in the sediment porewater.

Preparation and application research of transition metal phosphides

Due to the serious environmental pollution in the world, the shortcut to harmonious development is to improve traditional disposable energy and identify new energy sources that can be utilized. The current problem that human society must solve is to discover and use efficient and inexhaustible new energy sources, among which electrolytic water technology is an effective way to develop clean energy. In recent years, researchers have focused on producing hydrogen by electrolyzed water, but the intermediate hydrogen evolution reaction and the oxygen evolution reaction are relatively slow kinetic processes, and they cannot give the factory a large range of electrolytic water hydrogen production work and push down the commercialization process, so improving the rate of electrolytic water process must be an efficient catalyst. Transition metal phosphide is one of the non-precious metal catalysts in the electrochemical hydrogen evolution reaction and oxygen evolution reaction. Transition metal phosphide can promote rapid change of chemical reaction rate, and it has the characteristics of being cheap and easy to operate so it has a great prospect in the electrolysis of water. In this experiment, the oxygen evolution performance was optimized based on the crystal surface regulation of cobalt-doped transition metal nickel phosphide. The optimal reduction time and a small overpotential (60 mV) were obtained by using sodium borohydride to reduce the sample.

A novel method for the remediation of o‐ and p‐aminophenol from industrial wastewater by hexacyanoferrate (III) ions using Ir‐complex catalyst

AbstractIn this manuscript o‐ and p‐aminophenols model environmental pollutants are being remedied by catalytic oxidation process. A kinetic‐spectrophotometric technique was used to study the remediation of o‐ and p‐aminophenol by hexacyanoferrate (III) ions as an oxidant and synthesized Ir‐DTPy complex as a catalyst in aqueous alkaline medium. The optimum pH for these experiments was 9.0 and 11.0 for o‐ and p‐aminophenol respectively at the constant temperature 25°C. It has been studied how variations in the concentration of the catalyst (Ir‐DTPy), the hexacyanoferrate (III) ions, and substrate affect the rate of the reaction. At four different temperatures, ranging from 25 to 40°C, the change in reaction rate has been analyzed with thermodynamic variables like free energy of activation, enthalpy, frequency factor, and activation energy. FTIR, UV‐Vis, and ESI‐MS spectroscopic analytical methods have been used to identify the oxidized products. 2‐aminophenoxazin‐3‐one and NN'‐bis‐(p‐hydroxyphenyl)‐2‐hydroxy‐5‐amino‐1, 4‐benzoquinone di‐imine are the main products of oxidation of o‐and p‐aminophenol, respectively. Therefore, this technique for removing o‐ and p‐aminophenol from contaminated water resources is very effective and environmentally safe.

Direct Electrochemical Functionalization of Graphene Grown on Cu Including the Reaction Rate Dependence on the Cu Facet Type.

We present an electrochemical method to functionalize single-crystal graphene grown on copper foils with a (111) surface orientation by chemical vapor deposition (CVD). Graphene on Cu(111) is functionalized with 4-iodoaniline by applying a constant negative potential, and the degree of functionalization depends on the applied potential and reaction time. Our approach stands out from previous methods due to its transfer-free method, which enables more precise and efficient functionalization of single-crystal graphene. We report the suggested effects of the Cu substrate facet by comparing the reactivity of graphene on Cu(111) and Cu(115). The electrochemical reaction rate changes dramatically at the potential threshold for each facet. Kelvin probe force microscopy was used to measure the work function, and the difference in onset potentials of the electrochemical reaction on these two different facets are explained in terms of the difference in work function values. Density functional theory and Monte Carlo calculations were used to calculate the work function of graphene and the thermodynamic stability of the aniline functionalized graphene on these two facets. This study provides a deeper understanding of the electrochemical behavior of graphene (including single-crystal graphene) on Cu(111) and Cu(115). It also serves as a basis for further study of a broad range of reagents and thus functional groups and of the role of metal substrate beneath graphene.

Assessment of Bulk Oxygen Capacity and Transient Redox Behavior of Foamed Lanthanum Strontium Manganese Perovskites

Abstract Synthesis of solar thermochemical hydrogen (STCH) production redox materials with engineered structures, for example, replica foams, can enable efficient heat and mass transport and are critical for scaled-up systems. Prior work has motivated the use of lanthanum strontium manganese (LSM)-type perovskites as foamed STCH materials, but the effect of their morphology on bulk and kinetic behavior has not been reported. In this work, replica and direct foamed samples of La0.65Sr0.35MnO3-δ (LSM35) were fabricated and compared to synthesized powders and dense monoliths, and similarly synthesized CeO2-δ (ceria) foams, regarding their specific reaction rates and bulk oxygen capacity/H2 yields. Changes in oxygen capacity (Δδ) and reaction rates were measured between 1200 °C and 1400 °C by using fixed ratios of steam and hydrogen during both reduction and oxidation steps, allowing for analysis under practical high conversion conditions. Results suggest bulk behavior and reaction rates of the foamed LSM materials are comparable to their powder analogues. Differences in reaction rates were observed only when replica foamed samples were subjected to rapid laser heating (emulating conditions expected in solar furnaces), which is expected but has not been demonstrated at such a small scale. Foamed samples were further subjected to 50 redox cycles at 1400 °C to evaluate their stability. Results show no statistically significant decrease in hydrogen production for any of the foamed samples, but the direct foamed samples became brittle with time. Together, these results demonstrate the viability of replica foamed LSM perovskites for integration in scaled-up STCH systems.

Electrochemical Flow Reactor Design Allows Tunable Mass Transport Conditions for Operando Surface Enhanced Infrared Absorption Spectroscopy

AbstractIn situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR‐SEIRAS) is often used to investigate the near‐surface electrocatalytic reaction environment. However, there is a gap in directly correlating the near‐surface reaction environment with electrocatalytic reaction rates. To that end, we designed an electrochemical flow reactor for operando electrochemical ATR‐SEIRAS and demonstrate its capability with the CO2 reduction reaction (CO2RR). Roughened gold catalyst thin films are prepared on ATR silicon crystals as a model system to probe local species under CO2RR conditions in 0.1 M KHCO3. We measured changes in the interfacial CO2 concentration as a function of applied potential and electrolyte flow rate in operando, allowing us to correlate the changes in reaction rates with the observed CO2 concentration. Including the choice of the catalyst and electrolyte, coupling hydrodynamic control with ATR‐SEIRAS in this platform enables investigations of how the local microenvironment affects the activity and selectivity of electrochemical reactions.

Updating and evaluating the NH3 gas-phase chemical mechanism of MOZART-4 in the WRF-Chem model

The accuracy of determining atmospheric chemical mechanisms is a key factor in air pollution prediction, pollution-cause analysis and the development of control schemes based on air quality model simulations. However, the reaction of NH3 and OH to generate NH2 and its subsequent reactions are often ignored in the MOZART-4 chemical mechanism. To solve this problem, the gas-phase chemical mechanism of NH3 was updated in this study. Response surface methodology (RSM), integrated gas-phase reaction rate (IRR) diagnosis and process analysis (PA) were used to quantify the influence of the updated NH3 chemical mechanism on the O3 simulated concentration, the nonlinear response relationship of O3 and its precursors, the chemical reaction rate of O3 generation and the meteorological transport process. The results show that the updated NH3 chemical mechanism can reduce the error between the simulated and observed O3 concentrations and better simulate the O3 concentration. Compared with the Base scenario (original chemical mechanism simulated), the first-order term of NH3 in the Updated scenario (updated NH3 chemical mechanism simulated) in RSM passed the significance test (p < 0.05), indicating that NH3 emissions have an influence on the O3 simulation, and the effects of the updated NH3 chemical mechanism on NOx-VOC-O3 in different cities are different. In addition, the analysis of chemical reaction rate changes showed that NH3 can affect the generation of O3 by affecting the NOx concentration and NOx circulation with radicals of OH and HO2 in the Updated scenario, and the change of pollutant concentration in the atmosphere leads to the change of meteorological transmission, eventually leading to the reduction of O3 concentration in Beijing. In conclusion, this study highlights the importance of atmospheric chemistry for air quality models to model atmospheric pollutants and should attract more research focus.

Large-scale simulation of CO2 gasification reaction with mass transfer for metallurgical coke: Comparison with lab-scale experiment at 1373 K in early stage

The large-scale simulation of gasification using a highly resolved coke model is a powerful tool for predicting structural changes in metallurgical coke in a blast furnace. The objective of this study was to evaluate the accuracy of a numerical simulation using the results obtained from laboratory-scale gasification experiments. For the experiment, a cylindrical coke sample with a radius of 20 mm was gasified using CO2 gas at 1373 K in a coke gasification reaction furnace until the conversion reached 0.2. In addition, a numerical simulation of the coke model developed from X-ray computer tomography images of the coke sample before the reaction was conducted at 1373 K. Three low-resolution coke models were developed using the full-resolution coke model. The reaction rate and the coke structure after reaction were compared between the experiment and the numerical simulation. As a result, the prediction accuracies of reaction rate and structural change decreased with decreasing the image resolution as overall trend.

Degradation Diagnosis of Li(Ni0.5Mn0.2Co0.3)O2/Li Half-cell by Identifying Physical Parameter Evolution Profile Using Impedance Spectra During Cycling

Electrochemical Impedance Spectroscopy (EIS) is considered as a quick and nondestructive diagnostic tool to characterize the degradation of LIBs within a short testing timeframe. In this study, to obtain the relationship between EIS spectra and cell capacity degradation, our previously reported physics-based EIS model is further utilized to interpret EIS spectra of Li-NMC(5:2:3) half-cell measured under cycling. The EIS spectra show that the polarization impedance (Rp) increases with the number of cycles under different open circuit voltages (OCVs), especially in the mid-frequency range. After interpreting EIS spectra by the physics-based model, we found that the diffusion coefficient, ionic conductivity, and cathode reaction rate at different OCVs all decrease with the number of cycles. The impedance variation caused by the change of cathode reaction rate during cycles is much more significant than that caused by the other two parameters. Furthermore, the cell capacity degradation is linearly related to the charge transfer resistance (Rct2) caused by cathode/electrolyte interface reaction rate at specific OCVs and it could serve as the indicator of cell capacity fade beyond 10 cycles.

Improving the spatial control of soil biocementation using indigenous microorganisms: Column experiments and reactive transport modeling

Microbially-Induced Calcite Precipitation (MICP), or biocementation, is a biomediated soil improvement process that uses microbial ureolytic activity to enable the precipitation of CaCO3 on soil particle surfaces and contacts. As the technology advances towards practical adoption, approaches that can modulate the spatial uniformity of biocementation and maximize treatment extent will be critical towards reducing implementation costs and impacts. In this study, treatment strategies capable of enriching indigenous ureolytic microorganisms at controlled ureolytic activities and the effects of these techniques on resulting spatial distributions of MICP were explored using centimeter- and meter-scale soil column experiments and reactive transport simulations. In column experiments, differences in treatment solution supplied yeast extract concentrations were shown to reliably control the enrichment of indigenous ureolytic microorganisms and achieve a wide range of ureolytic activities. Reactive transport simulations further demonstrated that reductions in stimulated ureolytic rates could enable more uniform improvement and increases in the extent of improvement with reduced sensitivity to changes in solution injection velocities. A reaction-to-injection duration ratio (RTIDR) parameter was proposed and captured the collective impacts of changes in injection rates and ureolytic reaction rates on reactive transport conditions thereby unifying outcomes from both simulations and experiments. A nonuniformity area (NA) parameter was also introduced to quantitatively characterize differences in biocementation uniformity independent of length scale and CaCO3 magnitudes. Results from this study collectively demonstrate the utility of changes in stimulated ureolytic activities towards controlling the spatial uniformity and extent of biocementation over meter-scale distances.

Revealing Preservice Teachers’ Conceptions, Troublesome Knowledge and Threshold Concept of Chemical Equilibrium through Predict Observe Explain Mental Model Diagnostic Test (POE-MMDT)

The purpose of this study is to reveal preservice teacher’ conception of chemical equilibrium concepts which then were further analysed to identify the troublesome knowledge and threshold concept of chemical equilibrium. The participants of this study were 68 preservice chemistry teachers from one of the Teacher Education Institutions in Bandung, Indonesia. Using the descriptive-qualitative design, this research uses a predict-observe-explain mental model diagnostic test consisting of four main questions related to the phenomenon equilibrium process of the decomposition of N2O4 to become NO2. The findings show that most of the preservice teachers’ conceptions about chemical equilibrium are at the level of partial understanding, with five misconceptions has been identified in this study: (1) the reaction in chemical equilibrium is the same as an irreversible reaction; (2) the concentration of reactant and products are the same at equilibrium state; (3) gas with a greater concentration at equilibrium state can be determined from the gas that was first inserted to the container; (4) the concentration ratio at equilibrium is equal with the ratio of the coefficient reaction, and (5) the reactant is the gas which fills the container first. Further analysis shows that there are eight concepts in chemical equilibrium with troublesome knowledge characteristics, namely (1) the concentration of reactants and products in a state of equilibrium; (2) changes in the concentration of reactants and products to a state of equilibrium when starting from any side; (3) reactions that occur in an equilibrium state, (4) chemical equations for equilibrium reaction; (5) the rate of reactions in equilibrium state; (6) the change of reaction rate to reach an equilibrium state; (7) the relationship between Q and K; and (8) the calculation of reactants and products concentration at an equilibrium state. In addition, chemical equilibrium has two threshold concepts: the dynamic characteristic of equilibrium reaction and equilibrium constant. These findings show that the predict-observe-explain instrument has the potential to disclose PSTs’ mental model since it requires the participants to explain the prediction and its corresponding observation result. Besides, this instrument also guides the participants in explaining the macroscopic phenomena, which generates information about their understanding at the submicroscopic and symbolic levels. should be recognised as encompassed by and a form or part of “for all.”

Thermal effects on dispersion of secondary inorganic aerosols in an urban street canyon

The surface heating in complex urban areas affects concentration of secondary inorganic aerosol (SIA) via flow and chemical environment changes. Previous studies on heating effects on pollutants have focused on effect of dispersion change. However, the heating of buildings also affects SIA concentration via chemical environmental changes, such as reaction rate and thermodynamic equilibrium changes. Accordingly, we investigated the effect of heating, by not only flow changes but also chemical environment changes, on SIA using a coupled chemistry-computational fluid dynamics (CFD) model. We investigated the change of temperature and wind in each scenario to separately identify the effects caused by the chemistry and dynamics of thermal heating on reactive aerosols. We found that both the chemical and dynamical effects reduce SIA concentration. The effect of heating caused by chemical environment changes on SIA was 49.4% larger than that of flow changes, suggesting the importance of chemical reactions in aerosol calculations in urban microscale aerosol simulations, which are not considered in most CFD-based models. We conclude that chemical speciation and detailed aerosol chemistry calculations, including an inorganic aerosol thermodynamic equilibrium model, should be considered for accurately accounting for the effect of heating on urban areas.

Numerical study on the mixing process of hot desulfurization slag and converter steel slag

Slag mixing technique is a process that eliminates the lumping phenomenon of slag and iron in desulfurization slag. This process is conducted by mixing the high-temperature converter slag and iron desulfurization slag. The slag crushing difficulty is remarkably reduced after mixing. This technique eliminates the lumping phenomenon in the iron desulfurization slag. A numerical model based on Eulerian multiphase flow was established for the mixing process. The model obtained the characteristics of the phase field distribution inside the slag tank. The slag expansion phenomenon was identical with experimental results. A simplified temperature dropping model of slag mixing process was established based on the principle of energy conservation. According to this simplified model, the time dependence of the chemical reaction rate and temperature was investigated. The simplified model built by multifactor regression method can effectively predict the chemical reaction rate and temperature change under the following conditions: converter slag with an initial mass of 4–12 t, an initial iron oxide content of 20%–40%, an iron desulfurization slag mixing volume of 1–5 t, and an iron desulfurization slag mass flow rate of 0.1–1 t/s. The simplified model provides basic physical parameters for post-processing while ensuring safe production.

Solvent Deuterium Isotope Effects of Substrate Reduction by Nitrogenase from Azotobacter vinelandii.

The mechanism of nitrogenase, the enzyme responsible for biological nitrogen fixation, has been of great interest for understanding the catalytic strategy utilized to reduce dinitrogen to ammonia under ambient temperatures and pressures. The reduction mechanism of nitrogenase is generally envisioned as involving multiple cycles of electron and proton transfers, with the known substrates requiring at least two cycles. Solvent kinetic isotope effect experiments, in which changes of reaction rates or product distribution are measured upon enrichment of solvent with heavy atom isotopes, have been valuable for deciphering the mechanism of complex enzymatic reactions involving proton or hydrogen transfer. We report the distribution of ethylene, dihydrogen, and methane isotopologue products measured from nitrogenase-catalyzed reductions of acetylene, protons, and cyanide, respectively, performed in varying levels of deuterium enrichment of the solvent. As has been noted previously, the total rate of product formation by nitrogenase is largely insensitive to the presence of D2O in the solvent. Nevertheless, the incorporation of H/D into products can be measured for these substrates that reflect solvent isotope effects on hydrogen atom transfers that are faster than the overall rate-determining step for nitrogenase. From these data, a minimal isotope effect is observed for acetylene reduction (1.4 ± 0.05), while the isotope effects for hydrogen and methane evolution are significantly higher at 4.2 ± 0.1 and 4.4 ± 0.1, respectively. These results indicate that there are pronounced differences in the sensitivity to isotopic substitution of the hydrogen atom transfer steps associated with the reduction of these substrates by nitrogenase.

Effects of chemical boundary conditions on simulated O3 concentrations in China and their chemical mechanisms

Chemical boundary conditions (BCs) are important inputs for regional chemical transport models. In this study, we use the brute-force method (BFM), process analysis (PA) and response surface model (RSM) to quantify the effects of BCs on simulated O3 concentrations in different regions of China by the weather research and forecasting with chemistry (WRF–Chem) model. We combine the model with an integrated gas-phase reaction rate (IRR) tool to further analyze the changes in the O3 chemical mechanisms. Our results show that the simulated O3 concentrations in western cities are significantly affected by the O3 in the BCs (BC-O3), which can increase the maximum simulated O3 concentration, such as in Lanzhou (36.6 μg/m3, 26.3 %), Wuhai (30.1 μg/m3, 25.5 %) and Urumqi (50.7 μg/m3, 41.2 %). In contrast, O3 generation in the eastern region is dominated by emissions. Subsequently, we compare the reaction rate changes in O3 generation and consumption under the effects of BC-O3 in the western city of Urumqi and the eastern city of Beijing. The results show that in Beijing, the O3 concentration and the related chemical reaction rates undergo little change, while in Urumqi, the concentration and reaction rates have significant differences. The BC-O3 significantly accelerates the O3 photochemical reaction process in Urumqi, resulting in increased O3 generation and consumption reaction rates; additionally, there may be a chemical reaction pathway for the formation of O3: BC-O3 + NO → NO2 + hv → O + O2 → O3. BC-O3 transmission is the main pathway of changes in the simulated O3 concentration in the study area, and the chemical reactions between BC-O3 and local pollutants are primarily characterized by O3 consumption. In conclusion, the study shows the importance of BCs for regional model simulation while providing supporting information for O3 formation in model studies.

UV‐Induced C−H Functionalization of Alkanes with NO2 in Supercritical Carbon Dioxide

AbstractA novel catalyst‐free method for functionalization of unbranched alkanes via radical nitration with UV‐activated nitrogen oxide (IV) in supercritical carbon dioxide medium has been developed. The method allows to transform these inactive substrates into corresponding nitrates and nitro compounds with outstanding yields (up to 65 %), using available reagents (NO2, O2) under mild reaction conditions (35–50 °C), and exhibits lower hazards compared to conventional analogues. An improved selectivity towards the nitrates has been achieved by adding pure oxygen to the reaction. Based on changes in reaction rate and product composition, the plausible reaction mechanism for the UV‐induced C−H functionalization of alkanes with nitrogen oxide (IV) and pure oxygen has been proposed.

A new 12C + 12C nuclear reaction rate: Impact on stellar evolution

Context. By changing the internal composition of stars, nuclear reactions play a key role in their evolution and spur their contribution to the chemical evolution of galaxies. The STELLA collaboration recently carried out new direct measurements of the 12C + 12C fusion cross section – one of the key reactions occurring in C-burning regions in massive stars. Using a coincidence technique, accurate measurements were obtained for many different energies, with the lowest energy explored according to the Gamow window for massive stars. Aims. This work presents new 12C + 12C reaction rates in the form of numerical tables with associated uncertainty estimations, as well as analytical formulae that can be directly implemented into stellar evolution codes. We also describe the impact of these new rates on C-burning in stars. Methods. We determined reaction rates for two cross section extrapolation models: one based on the fusion-hindrance phenomenon and the other on fusion-hindrance plus a resonance. We then compared our results to prior data. Using the GENEC stellar evolution code, we study how these new rates impact the C-burning phases in two sets of stellar models for stars with 12 M⊙ and 25 M⊙ initial masses, which were chosen to be highly representative of the diversity of massive stars. Results. The effective temperatures of C-burning in both sets of stellar models are entirely covered by the sensitivity of the present experimental data and no extrapolation of the rates is required. Although the rates may differ by more than an order of magnitude for temperatures typical of C-burning, the impacts on the stellar structures during that phase remain modest. This is a consequence of the readjustment of the stellar structure to a change of nuclear reaction rate for reactions that are shown to be important for energy production. For the hindrance case, the C-burning phase is found to occur at central temperatures that are 10% higher than with the hindrance plus resonance rate. Its C-burning lifetime is reduced by a factor of two. This model, nevertheless, loses more entropy than the other one; thus, it enters into the degeneracy regime earlier, which will impact the last stages of the evolution at the pre-core collapse time. The hindrance model produces up to 60% more neon. The impact of the different rates on the s-process occurring during the C-burning phase is modest, affecting the final abundances of s-processed elements by at most 20% (cobalt).

Crystallization of struvite in the presence of calcium ions: Change in reaction rate, morphology and chemical composition

Crystallization of struvite in the presence of calcium ions: Change in reaction rate, morphology and chemical composition