Hydroxide and Hydronium Ions Modulate the Dynamic Evolution of Nitrogen Nanobubbles in Water.

It has been widely recognized that the pH environment influences the nanobubble dynamics and hydroxide ions adsorbed on the surface may be responsible for the long-term survival of the nanobubbles. However, understanding the distribution of hydronium and hydroxide ions in the vicinity of a bulk nanobubble surface at a microscopic scale and the consequent impact of these ions on the nanobubble behavior remains a challenging endeavor. In this study, we carried out deep potential molecular dynamics simulations to explore the behavior of a nitrogen nanobubble under neutral, acidic, and alkaline conditions and the inherent mechanism, and we also conducted a theoretical thermodynamic and dynamic analysis to address constraints related to simulation duration. Our simulations and theoretical analyses demonstrate a trend of nanobubble dissolution similar to that observed experimentally, emphasizing the limited dissolution of bulk nanobubbles in alkaline conditions, where hydroxide ions tend to reside slightly farther from the nanobubble surface than hydronium ions, forming more stable hydrogen bond networks that shield the nanobubble from dissolution. In acidic conditions, the hydronium ions preferentially accumulating at the nanobubble surface in an orderly manner drive nanobubble dissolution to increase the entropy of the system, and the dissolved nitrogen molecules further strengthen the hydrogen bond networks of systems by providing a hydrophobic environment for hydronium ions, suggesting both entropy and enthalpy effects contribute to the instability of nanobubbles under acidic conditions. These results offer fresh insights into the double-layer distribution of hydroxide and hydronium near the nitrogen-water interface that influences the dynamic behavior of bulk nanobubbles.

Regulator of G protein signaling 1 is a potential target in gastric cancer and impacts tumor-associated macrophages.

Regulator of G protein signaling 1 (RGS1) is closely associated with the tumor immune microenvironment and is highly expressed in various tumors and immune cells. The specific effects of RGS1 in the dynamic progression from chronic gastritis to gastric cancer have not been reported, and the role of tumor-associated macrophages (TAMs) is also unclear. In the present study, RGS1 was identified as an upregulated gene in different pathological stages ranging from chronic gastritis to gastric cancer by using Gene Expression Omnibus (GEO) screening together with pancancer analysis of The Cancer Genome Atlas and clinical prognostic analysis. The results indicated that RGS1 is highly expressed in gastric cancer and has potential prognostic value. We confirmed through in vivo experiments that RGS1 inhibited the proliferation of gastric cancer cells and promoted apoptosis, which was further corroborated by in vitro experiments. Additionally, RGS1 influenced cell migration and invasion. In our subsequent investigation of RGS1, we discovered its role in the immune response. Through analyses of single-cell and GEO database data, we confirmed its involvement in immune cell regulation, specifically TAM activation. Subsequently, we conducted in vivo and in vitro experiments to confirm the involvement of RGS1 in polarizing M1 macrophages while indirectly regulating M2 macrophages through tumor cells. In conclusion, RGS1 could be a potential target for the transformation of chronic gastritis into gastric cancer and has a measurable impact on TAMs, which warrants further in-depth research.

Intramolecular and Water Mediated Tautomerism of Solvated Glycine.

Understanding tautomerism and characterizing solvent effects on the dynamic processes pose significant challenges. Using enhanced-sampling molecular dynamics based on state-of-the-art deep learning potentials, we investigated the tautomeric equilibria of glycine in water. We observed that the tautomerism between neutral and zwitterionic glycine can occur through both intramolecular and intermolecular proton transfers. The latter proceeds involving a contact anionic-glycine-hydronium ion pair or separate cationic-glycine-hydroxide ion pair. These pathways with comparable barriers contribute almost equally to the reaction flux.

The investigation of thrombocytopenia after transcatheter occlusion of patent ductus arteriosus.

OBJECTIVE: To investigate the risk factors for thrombocytopenia after transcatheter occlusion operation of patent ductus arteriosus (PDA). METHOD: Retrospective analyses were conducted using clinical data from 106 patients with PDA who underwent transcatheter closure operations at Henan Provincial Chest Hospital, Zhengzhou University, from January 2018 to June 2022. The study compared the changes in platelet counts before and after the operation, and investigated the risk factors for thrombocytopenia following PDA closure in different groups and layers. RESULTS: The platelet count of patients with PDA significantly decreased after undergoing transcatheter PDA occlusion. Logistic regression analysis revealed that factors such as PDA diameter, occluder diameter, pressure difference on the two sides of the occluder, and residual shunt were associated with an increased risk of thrombocytopenia following PDA occlusion. Specifically, the size of the occluder and the pressure difference between the two sides of the occluder were found to have a negative correlation with the postoperative platelet count. Further subgroup analysis demonstrated that the incidence of total thrombocytopenia was significantly higher in the large PDA group compared to the small-medium PDA groups. CONCLUSION: Our findings suggest that occluder diameter, the pressure difference between the two sides of the occluder, and the residual shunt are major risk factors correlated with the incidence of postoperative thrombocytopenia. However, a multicenter and long-term prospective study is required to further evaluate the prognosis of PDA patients with thrombocytopenia after transcatheter occlusion.

Engineering Amorphous/Crystalline Ru(OH)3/CoFe-Layered Double Hydroxide for Hydrogen Evolution at 1000 mA cm-2.

For large-scale industrial applications, it is highly desirable to create effective, economical electrocatalysts with long-term stability for the hydrogen evolution reaction (HER) at a large current density. Herein, we report a unique motif with crystalline CoFe-layered hydroxide (CoFe-LDH) nanosheets enclosed by amorphous ruthenium hydroxide (a-Ru(OH)3/CoFe-LDH) to realize the efficient hydrogen production at 1000 mA cm-2, with a low overpotential of 178 mV in alkaline media. During the continuous HER process for 40 h at such a large current density, the potential remains almost constant with only slight fluctuations, indicating good long-term stability. The remarkable HER performance can be attributed to the charge redistribution caused by abundant oxygen vacancies in a-Ru(OH)3/CoFe-LDH. The increased electron density of states lowers the charge-transfer resistance and promotes the formation and release of H2 molecules. The water-splitting electrolyzer with a-Ru(OH)3/CoFe-LDH as both an anode and a cathode in 1.0 M KOH demonstrates stable hydrogen production and a 100% faradic efficiency. The design strategy of interface engineering in this work will inspire the design of practical electrocatalysts for water splitting on an industrial scale.

Ketogenic diet inhibits neointimal hyperplasia by suppressing oxidative stress and inflammation.

OBJECTIVE: Neointimal hyperplasia is the primary mechanism underlying atherosclerosis and restenosis after percutaneous coronary intervention. Ketogenic diet (KD) exerts beneficial effects in various diseases, but whether it could serve as non-drug therapy for neointimal hyperplasia remains unknown. This study aimed to investigate the effect of KD on neointimal hyperplasia and the potential mechanisms. METHODS AND RESULTS: Carotid artery balloon-injury model was employed in adult Sprague-Dawley rats to induce neointimal hyperplasia. Then, animals were subjected to either standard rodent chow or KD. For in-vitro experiment, impacts of ß-hydroxybutyrate (ß-HB), the main mediator of KD effects, on platelet-derived growth factor BB (PDGF-BB) induced vascular smooth muscle cell (VSMC) migration and proliferation were determined. Balloon injury induced event intimal hyperplasia and upregulation of protein expression of proliferating cell nuclear antigen (PCNA) and α-smooth muscle actin (α-SMA), and these changes were significantly ameliorated by KD. In addition, ß-HB could markedly inhibit PDGF-BB induced VMSC migration and proliferation, as well as inhibiting expressions of PCNA and α-SMC. Furthermore, KD inhibited balloon-injury induced oxidative stress in carotid artery, indicated by reduced ROS level, malondialdehyde (MDA) and myeloperoxidase (MPO) activities, and increased superoxide dismutase (SOD) activity. We also found balloon-injury induced inflammation in carotid artery was suppressed by KD, indicated by decreased expressions of proinflammatory cytokines IL-1ß and TNF-α, and increased expression of anti-inflammatory cytokine IL-10. CONCLUSION: KD attenuates neointimal hyperplasia through suppressing oxidative stress and inflammation to inhibit VSMC proliferation and migration. KD may represent a promising non-drug therapy for neointimal hyperplasia associated diseases.

Theoretical Kinetics studies of isoprene peroxy radical chemistry: The fate of Z-δ-(4-OH, 1-OO)-ISOPOO radical.

The OH radical recycling mechanism in isoprene oxidation is one of the most exciting topics in atmospheric chemistry, and the corresponding studies expand our understanding of oxidation mechanisms of volatile organic compounds in the troposphere and provide reliable evidence to improve and develop conventional atmospheric models. In this work, we performed a detailed theoretical kinetics study on the Z-δ-(4-OH, 1-OO)-ISOPOO radical chemistry, which is proposed as the heart of OH recycling in isoprene oxidation. With the full consideration of its accumulation and consumption channels, we studied and discussed the fate of Z-δ-(4-OH, 1-OO)-ISOPOO radical by solving the energy-resolved master equation over a broad range of conditions, including not only room temperatures but also high temperatures of a forest fire or low temperatures and pressures of the upper troposphere. We found non-negligible pressure dependence of its fate at combustion temperatures (up to two orders of magnitude) and demonstrated the significance of both the multi-structural torsional anharmonicity and tunneling for accurately calculating kinetics of the studied system. More interestingly, the tunneling effect on the phenomenological rate constants of the H-shift reaction channel is also found to be pressure-dependent due to the competition with the O2 loss reaction. In addition, our time evolution calculations revealed a two-stage behavior of critical species in this reaction system and estimated the shortest half-lives for the Z-δ-(4-OH, 1-OO)-ISOPOO radical at various temperatures, pressures and altitudes. This detailed kinetics study of Z-δ-(4-OH, 1-OO)-ISOPOO radical chemistry offers a typical example to deeply understand the core mechanism of OH recycling pathways in isoprene oxidation, and provides valuable insights for promoting the development of relevant atmospheric models.

Influence of an Axial-Electromagnetic Field Treatment Device with a Solenoid Structure on Crystallization Fouling on the Tube Side of a Shell-and-Tube Heat Exchanger.

In this study, the influence of an axial-electromagnetic field treatment device (AEFTD) with a solenoid structure using different electromagnetic frequencies on calcium carbonate (CaCO3) crystallization fouling on the tube side of a shell-and-tube heat exchanger was investigated. The experimental results indicated that the application of the AEFTD could effectively reduce fouling resistance and decelerate the growth rate of CaCO3 fouling. The opposite trend between fouling resistance and the outlet temperature of an experimental fluid indicated that the application of the AEFTD could enhance heat transfer. Meanwhile, the crystal morphologies of the fouling samples were analyzed by means of scanning electron microscopy (SEM). The axial-electromagnetic field favored the formation of vaterite as opposed to calcite. Non-adhesive vaterite did not easily aggregate into clusters and was suspended in bulk to form muddy fouling that could be carried away by turbulent flow. Furthermore, the anti-fouling mechanism of the axial-electromagnetic field is discussed in detail. The anti-fouling effect of the AEFTD on CaCO3 fouling exhibited extreme characteristics in this study. Therefore, the effectiveness of the AEFTD is contingent upon the selection of the electromagnetic parameters.

HuangJinShuangShen granules can improve immunity and enhance the ability of 5-fluorouracil to induce apoptosis of gastric cancer cells.

In recent years, Chinese herbal compounds have gained significant prominence in the treatment of gastric cancer. The goal of this study was to investigate the antitumor effect of HuangJinShuangShen granules (HJSS) combined with 5-fluorouracil on MFC gastric cancer mice. In this study, the MFC model with gastric cancer was successfully established. After continuous administration for 14 d, the body weight, tumor volume and weight and spleen mass of mice in each group were recorded. The levels of IFN-γ and TGF-ß1 in serum were detected by ELISA. The expression of apoptosis proteins in tumor tissues was detected by Western blotting. Compared with the model group and the 5-FU group, the combined drug group can significantly inhibit tumor growth, reduce tumor volume, promote tumor cell necrosis and increase spleen index in mice. At the same time, the combined treatment group significantly increased IFN-γ level and BAX protein expression, decreased TGF-ß1 level and decreased Bcl2, Caspase-9 and Cleaved Caspase-3 protein expressions. These findings provide evidence that HJSS can augment the suppressive impact of 5-FU on tumor growth in gastric cancer mice, potentially through the induction of tumor cell apoptosis and the restoration of immune function.

Master equation study of hydrogen abstraction from HCHO by OH via a chemically activated intermediate.

The abstraction reaction of hydrogen from formaldehyde by OH radical plays an important role in formaldehyde oxidation. The reaction involves a bimolecular association to form a chemically activated hydrogen-bonded reaction complex followed by a unimolecular reaction of the complex to generate the products. The reaction rate is usually considered to be pressure-independent by assuming equilibrium between the reactants and the complex. However, our nonequilibrium calculations based on the chemically significant eigenmode of the master equation, carried out with our recently developed TUMME program, indicate that the reaction complex makes the rate constant dependent on pressure at low temperatures (T < 200 K). The calculations include anharmonicity, variational effects, and multi-dimensional tunneling. We find that the reaction rate constant reaches a low-pressure limit at pressures below 10 Torr over the whole investigated temperature range (20-1800 K), which explains why the available low-temperature experiments, which are for pressures below 2 Torr, did not observe the pressure dependence. A new extension of the TUMME master-equation program is used to explore the time evolutions of the concentrations of the OH radical and the complex under pseudo-first-order conditions. The time-dependent evolution of the concentrations of the complex at a low temperature provide direct evidence for the stabilization of the reaction complex at high pressures, and it shows the negligible role of the stabilized reaction complex at low pressures. The picture that emerges is qualitatively consistent with our previous study of the reaction of methanol with OH in that the tunneling in the unimolecular step from the complex to the products affects the phenomenological reaction rate constants differently at high and low pressures and leads to a significant pressure effect.

How sodium chloride extends lifetime of bulk nanobubbles in water.

We present a molecular dynamics simulation study on the effects of sodium chloride addition on stability of a nitrogen bulk nanobubble in water. We find that the lifetime of the bulk nanobubble is extended in the presence of NaCl and reveal the underlying mechanisms. We do not observe spontaneous accumulation or specific arrangement of ions/charges around the nanobubble. Importantly, we quantitatively show that the N2 molecule selectively diffuses through water molecules rather than pass by any ions after it leaves the nanobubble due to the much weaker water-water interactions than ion-water interactions. The strong ion-water interactions cause hydration effects and disrupt hydrogen bond networks in water, which leave fewer favorable paths for the diffusion of N2 molecules, and by that reduce the degree of freedom in the dissolution of the nanobubble and prolong its lifetime. These results demonstrate that the hydration of ions plays an important role in stability of the bulk nanobubble by affecting the dynamics of hydrogen bonds and the diffusion properties of the system, which further confirm and interpret the selective diffusion path of N2 molecules and the extension of lifetime of the nanobubble. The new atomistic insights obtained from the present research could potentially benefit the practical application of bulk nanobubbles.

Ultrasonic-assisted decoration of Ag2WO4, AgI, and Ag nanoparticles over tubular g-C3N4: Plasmonic photocatalysts for impressive removal of tetracycline under visible light.

The development of an efficient, eco-friendly, and low-cost photocatalyst is essential for addressing environmental and energy crises. In this regard, we report novel plasmonic photocatalysts through adorning tubular g-C3N4 with Ag2WO4, Ag, and AgI nanoparticles (TGCN/Ag/Ag2WO4/AgI) fabricated via a facile ultrasonic-irradiation procedure. The TGCN/Ag/Ag2WO4/AgI (20%) nanocomposite presented the excellent photocatalytic ability for removal of tetracycline hydrochloride under visible light, which was almost 45.6, 4.03, and 1.32 times more than GCN, TGCN, and TGCN/Ag/Ag2WO4 (20%) photocatalysts, respectively. Interestingly, the photocatalyst displayed impressive ability for the degradations of amoxicilline, rhodamine B, methyl orange, fuchsine, and methylene blue, which was 14.7, 52.2, 9.8, 13.2, and 7.46 times as much as pure GCN. The outcomes of DRS, PL, EIS, and photocurrent density analyses proved that the impressive activity could be related to the highly promoted harvesting of visible light, segregation of charge carriers, and improved charge migrations. In addition, trapping tests exhibited that •O2- and h+ were active species in the photocatalysis process.

Pressure-dependent kinetics of the o-xylene reaction with OH radicals.

OH-initiated oxidation reactions of o-xylene are widely concerned both in combustion and atmospheric chemistry. In this work, the kinetics of the o-xylene reaction with OH radicals has been studied systematically in a wide temperature range of 220-3000 K for the high-pressure limit and several selected pressures from 1 torr to 500 atm using multi-structural variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT) and the system-specific quantum Rice-Ramsperger-Kassel (SS-QRRK) method. The calculations fully considered various factors which could affect the accuracy of the calculated rate constants including anharmonicity of both low- and high-frequency modes and multiple low-energy conformers, variational effect, and tunneling. The results are in good agreement with the available experimental data. The obtained overall rate constants exhibit a nonmonotonic temperature dependence due to the competition between the hydrogen abstraction and addition reactions. At low temperatures, the addition channels are dominant reactions, but the abstraction reactions are also non-ignorable with a ∼12% contribution to the overall rate constants at 298 K and 1 atm. Above 800 K, the abstraction reactions become dominant under all the pressure conditions. In addition, we observed a more significant pressure dependence of o-xylene plus OH reaction as compared to the similar toluene plus OH reaction, which is the effect of the additional methyl group. At T = 500-1000 K, the pressure can influence the total rate constants of the o-xylene reaction by a factor of up to 2.5. These kinetics data provide us with a comprehensive understanding of the mechanism and pressure-dependence of kinetics for the o-xylene + OH reaction, which is also beneficial for the study of other similar aromatic hydrocarbon reactions.

Observing Intramolecular Vibrational Energy Redistribution via the Short-Time Fourier Transform.

Intramolecular vibrational energy relaxation (IVR) is important in many problems in chemical physics. Here, we apply the short-time Fourier transform method for analyzing IVR with classical dynamics. Calculating time-dependent Fourier transforms to perform such an analysis requires extending the usual Fourier transform method, and we do that here. The guiding concept behind the generalization is that if there is a shift of vibrational energy from one frequency range to another, we see a difference between the spectrum before the shift and the spectrum after the shift. We use time-window functions to transform the power spectrum of a trajectory into a time-dependent density spectrum of the average kinetic energy. The time-dependent average kinetic energy for each interval of the spectrum becomes an indicator to monitor the extent and nature of the energy transfer into and out of the corresponding modes. We illustrate this method for the H2O molecule. By analyzing cases with different initial conditions, we show that the short-time Fourier transform method can distinguish trends in IVR that depend on the initial distribution of energy and not just on the total energy.

A chemically consistent rate constant for the reaction of nitrogen dioxide with the oxygen atom.

In the present study, a chemically consistent rate constant for the reaction between nitrogen dioxide and the oxygen atom has been obtained by combining low-temperature experimental data from the literature and new high-temperature quantum chemical calculations. The expression for our rate constant is kNO2+O=NO+O2= 2.589 × 1015T-1.035 exp(-226/RT) + 4.242 × 1016T-0.861exp(-50 917/RT) cm3 mol-1 s-1, where R = 8.314 J mol-1 K-1, and is valid over the temperature range T = 221 to 3000 K. The effect of the inclusion of the new rate constant on the prediction of three detailed reaction models from the literature has been studied using (i) new experimental oxygen atom profiles obtained in a shock tube during nitrogen dioxide pyrolysis, and (ii) published shock tube and jet-stirred reactor data for H2-NOx mixtures with and without dioxygen. The impact of the new rate constant on the sensitivity coefficients and reaction pathways has also been analyzed under some conditions. Overall, the predictive capability of the reaction models were improved. The present study suggests that our chemically consistent rate constant should be included in detailed reaction models for combustion applications.

Correction: A kinetics study on hydrogen abstraction reactions of cyclopentane by hydrogen, methyl, and ethyl radicals.

Correction for 'A kinetics study on hydrogen abstraction reactions of cyclopentane by hydrogen, methyl, and ethyl radicals' by Wenqi Chen et al., Phys. Chem. Chem. Phys., 2021, 23, 7333-7342, DOI: 10.1039/D1CP00386K.

A kinetics study on hydrogen abstraction reactions of cyclopentane by hydrogen, methyl, and ethyl radicals.

Hydrogen abstraction reactions of (cyclo)alkanes by radicals play a fundamental role in both combustion and atmospheric chemistry. In this work, we select three common radicals in the pyrolysis of hydrocarbon fuels: hydrogen radical (H[combining dot above]), methyl radical (CH3), and ethyl radical (CH2CH3) to investigate the kinetics of their hydrogen abstraction reactions with cyclopentane. The rate constants over a broad temperature range of 150-3000 K are calculated by using the multi-structural variational transition state theory in the small-curvature tunneling approximation (MS-CVT/SCT), by which the multi-structural torsional (MS-T) anharmonicity of partition functions, variational effects, and corner-cutting tunneling are all included in dynamics calculations. We stress the particular importance of considering the MS-T anharmonicity in the rate constant calculation for the reaction with the ethyl radical compared to those with hydrogen and methyl radicals. The MS-T anharmonicity significantly accelerates the reaction with the ethyl radical in the whole temperature range, and in particular, it increases the rate constant by a factor of >-9 at 1000 K. We also found that the tunneling effect drastically increases the rate constants at low-temperatures by up to 3-5 orders of magnitudes. The calculated reaction rate constants have an order of .

Energy Dependence of Ensemble-Averaged Energy Transfer Moments and Its Effect on Competing Decomposition Reactions.

We carried out a direct dynamics study on the internal-energy dependence of the ensemble-averaged energy transfer moments of the isobutyl radical in collisions with N2 bath gas. We find a linear dependence of the downward moment ⟨ΔEd⟩ and the root-mean-square moment ⟨ΔE2⟩ on the initial internal energy, but the upward moment ⟨ΔEu⟩ is found to be independent of the molecule's internal energy. We improved the exponential-down relaxation model by including a linear dependence of ⟨ΔEd⟩ on the initial energy, and we used the improved treatment in the 1D master equation for isobutyl radical decomposition reactions and for a model of competitive reactions with a larger difference in barrier heights. We calculated phenomenological rate constants and branching ratios from chemically significant eigenmodes of the master equation and showed that the energy dependence of ⟨ΔEd⟩ has a greater influence on channels with higher barriers in competitive reactions. Rate constants and branching ratios from master equation calculations indicate that for a given temperature and pressure, there is a constant ⟨ΔEd⟩ that can reproduce results obtained with an E-dependent ⟨ΔEd⟩. But a constant ⟨ΔEd⟩ cannot do this for all temperatures and pressures, with larger differences when the barriers for the competing channels differ more. We conclude that when the branching ratio of competitive reactions is sensitive to pressure, including the energy dependence of ⟨ΔEd⟩ in master equation simulations can make a significant difference in the results.

Relationship of Anxiety and Depression with Perfectionism in Patients with Aesthetic All-Ceramic Repair of Anterior Teeth.

BACKGROUND Many psychological problems arising from patients undergoing aesthetic repair of teeth should be considered. However, there are no published studies on the relationship between anxiety/depression and perfectionism in patients with aesthetic repair of anterior teeth. MATERIAL AND METHODS A total of 640 patients receiving aesthetic repair of anterior teeth were assessed using the Corah dental anxiety scale (CDAS), a self-rating anxiety scale (SAS), a self-rating depression scale (SDS), and the Chinese version of the Frost Multidimensional Perfectionism Psychological Scale (CFMPS). Statistical analyses included use of the independent-samples t test, correlation analysis, and multiple stepwise regression analysis. RESULTS We found that 156 patients with a high dental anxiety disorder had significantly greater SAS and SDS scores than those without a high dental anxiety disorder. There were significant differences between these patients and the non-high dental anxiety group, based on 3 dimensions of the CFMPS: concern over mistakes (CM), doubt about action (DA), and organization (OR). Patients with dental anxiety had a significant positive correlation with SAS in the categories CM and DA, with SDS in the categories CM and DA, and with personal standard (PS); OR was negatively correlated with SAS and SDS scores. Regression analysis showed that the CM and OR dimension scores of CFMPS and age had strong predictive effects on SAS scores, while CM, DA, PS dimension scores, and age were strong predictors of SDS scores. CONCLUSIONS The incidence of dental anxiety prior to anterior tooth repair treatment is high, and patients with dental anxiety have a significant tendency toward pursuing perfectionism.

Low-Pressure Limit of Competitive Unimolecular Reactions.

Barker and Ortiz found unusual falloff effects in the flux coefficients of the competitive unimolecular reactions of 2-methylhexyl radicals, and they concluded that this might have important effects on the rate constants of reactions with higher thresholds. To study this effect, we carried out master equation calculations of the same reaction system to learn whether this effect shows up in measurable rate constants, and the answer is yes. We also studied specially designed mechanisms to reveal that the various reactive pathways connecting the reagents can have a large effect on the rate constants, causing them to be quite different than if the reactions proceeded independently, and that reactions with significantly higher barriers may nevertheless have larger rate constants. This provides a new perspective for interpreting and predicting the kinetics of competitive unimolecular reactions.