Complex Reaction Research Articles

Testing the hypothesis that solvent exchange limits the rates of calcite growth and dissolution.

It is established that the rates of solvent exchange at interfaces correlate with the rates of a number of mineral reactions, including growth, dissolution and ion sorption. To test if solvent exchange is limiting these rates, quasi-elastic neutron scattering (QENS) is used here to benchmark classical molecular dynamics (CMD) simulations of water bound to nanoparticulate calcite. Four distributions of solvent exchanges are found with residence times of 8.9 ps for water bound to calcium sites, 14 ps for that bound to carbonate sites and 16.7 and 85.1 ps for two bound waters in a shared calcium-carbonate conformation. By comparing rates and activation energies, it is found that solvent exchange limits reaction rates neither for growth nor dissolution, likely due to the necessity to form intermediate states during ion sorption. However, solvent exchange forms the ceiling for reaction rates and yields insight into more complex reaction pathways.

Deciphering complexity in Pd–catalyzed cross-couplings

Understanding complex reaction systems is critical in chemistry. While synthetic methods for selective formation of products are sought after, oftentimes it is the full reaction signature, i.e., complete profile of products/side-products, that informs mechanistic rationale and accelerates discovery chemistry. Here, we report a methodology using high-throughput experimentation and multivariate data analysis to examine the full signature of one of the most complicated chemical reactions catalyzed by palladium known in the chemical literature. A model Pd-catalyzed reaction was selected involving functionalization of 2-bromo-N-phenylbenzamide and multiple bond activation pathways. Principal component analysis, correspondence analysis and heatmaps with hierarchical clustering reveal the factors contributing to the variance in product distributions and show associations between solvents and reaction products. Using robust data from experiments performed with eight solvents, for four different reaction times at five different temperatures, we correlate side-products to a major dominant N-phenyl phenanthridinone product, and many other side products.

MS and NMR Analysis of Isotopically Labeled Chloramination Disinfection Byproducts: Hyperlinks and Chemical Reactions.

FT-ICR MS and NMR analysis of an isotopically labeled complex mixture of water disinfection byproducts formed by chloramine disinfection of model phenolic acids is described. A new molecular formula assignment procedure using the CoreMS Python library able to assign isotopically enriched formulas is proposed. Statistical analysis of the assigned formulas showed that the number of compounds, the diversity of the mixture, and the chlorine count increase during the chloramination reaction. The complex reaction mixture was investigated as a network of reactions using PageRank and Reverse PageRank algorithms. Independent of the MS signal intensities, the PageRank algorithm calculates the formulas with the highest probability at convergence of the reaction; these were chlorinated and nitrated derivatives of the starting materials. The Reverse PageRank revealed that the most probable chemical transformations in the complex mixture were chlorination and decarboxylation. These agree with the data obtained from INADEQUATE NMR spectra and literature data, indicating that this approach could be applied to gain insight into reactions pathways taking place in complex mixtures without any prior knowledge.

THE IMPACT OF STRESS-ASSOCIATED DISEASES OF THE DIGESTIVE ORGANS ON THE PSYCHOPHYSIOLOGICAL STATE OF OPERATORS OF UNMANNED AIRCRAFT SYSTEMS

Introduction. In the conditions of martial law, an important role belongs to modern military equipment, which includes unmanned aircraft systems (UAS). Оperators of UAS in the course of combat missions are significantly affected by the stress factor. It provokes the occurrence of stress-associated diseases in them, therefore, studying the specifics of the impact of stress-associated diseases on the psychophysiological state of operators determines the relevance of this study. The purpose of the study. To establish the patterns of influence of stress-associated diseases of the digestive organs on the psychophysiological state of the operators of unmanned aircraft systems. Materials and methods. In the course of the research, 94 operators of UAS under the age of 40 were examined, who were then divided into groups based on their health status. The examination was carried out using modern modified methods implemented on the basis of the software and hardware complex for psychophysiological research «PFI-2». The results. It has been proven that stress-associated diseases of the digestive organs significantly worsen (p<0,05) the psychophysiological state of operators of UAS in a sufficiently large number of professionally important psychophysiological qualities. The reliable influence of the «state of health» factor on the indicators of simple and complex visual-motor reaction of operators of UAS is shown. The analysis of correlation constellations according to cognitive parameters showed that 6 of them are observed in healthy operators, 2 in mildly ill patients, and 1 in severely ill patients, that is, the system of connections between cognitive functions breaks down quite strongly with the development of stress-associated diseases of the digestive organs. There is a natural decrease in the number of connections in the series «healthy (13) – mildly ill (10) – severely ill (5)». It is shown that the stress that causes the disease fundamentally destroys the system of ensuring professional activity. Conclusions. It was established that stress-associated diseases of the digestive organs negatively affect the psychophysiological state of operators. The degree of degradation of the structure of correlation relations (р=0,0491) as a result of the influence of the stress factor on the operators was revealed. A hypothesis regarding the destruction of the system of connections between cognitive psychophysiological parameters depending on the «severity of the disease» is proposed. The need to develop a set of measures to prevent the development of stress-related diseases among operators of UAS has been established.

Development e-module on genetic materials to enhance student’s critical thinking skills

Genetic material is classified as material that is difficult for students to understand because the material is abstract, there are many foreign terms, and there are many complex molecular reactions, so students have difficulty developing critical thinking skills. Therefore, developing a good, suitable, effective, and attractive media is necessary. . This study aims to develop an e-module on the topic of genetic substance, to test the feasibility of the e-module, and to determine the differences in critical thinking skills before and after the implementation of the e-module. This type of research is research and development research with a 4D Thiagarajan model consisting of define, design, development,and disseminate. . This research was conducted without the dissemination stage. The results of the validation of media experts are 81.7% (fair enough) and material experts are 85.5% (very feasible). The results of the trial were limited to 10 students, namely 92.1% (very decent) and 80.4% biology teachers (quite decent). The results of field trials are 90.2% (very feasible). The results of the t-test indicate that there are differences in critical thinking skills before and after the implementation of the e-module. This study implicate that e-modules on the topic of genetic substances are feasible to use and to empower students’s critical thinking skills.

Partial Oxidation of Methanol on Gold: How Selectivity Is Steered by Low-Coordinated Sites.

Partial methanol oxidation proceeds with high selectivity to methyl formate (MeFo) on nanoporous gold (npAu) catalysts. As low-coordinated sites on npAu were suggested to affect the selectivity, we experimentally investigated their role in the isothermal selectivity for flat Au(111) and stepped Au(332) model surfaces using a molecular beam approach under well-defined conditions. Direct comparison shows that steps enhance desired MeFo formation and lower undesired overoxidation. DFT calculations reveal differences in oxygen distribution that enhance the barriers to overoxidation at steps. Thus, these results provide an atomic-level understanding of factors controlling the complex reaction network on gold catalysts, such as npAu.

Isoconversional approach to quantitative assessment of reactivity under non-isothermal conditions

The present paper proposes the isoconversional approach to a quantitative assessment of the reactivity in elementary and complex reactions studied by thermal methods under non-isothermal conditions. The focus is on the processes studied at a constant heating rate as the most common mode used in thermal analysis. The accuracy of the proposed approach is tested on simulated data for elementary reactions, whereas its practical application is demonstrated on few experimental examples. The effect of experimental uncertainties on the precision of the introduced reactivity factors is also considered.

Sintering behavior and densification mechanism of MoOx targets obtained by hot pressing

MoOx targets for magnetron sputtering Mo–O films were obtained by vacuum hot pressing sintering. MoOx powder was obtained by hydrogen reduction of MoO3, and the O/Mo atomic ratio was determined by the k-value method. The sintering behavior and densification mechanism of the MoOx target were analyzed by exploring the influence of hot pressing sintering pressure, temperature, and holding time on the target's density, phase composition, and morphology. MoOx targets with different oxygen content were sintered using MoOx powder with O/Mo of 2.838, 2.679, and 2.494, respectively. The results reveal that complex reactions occur in the shrinkage stage of sintering. The content of Mo4O11 increases, the content of Mo9O26 and MoO2 decreases, and the oxygen content of the targets is positively correlated with the content of MoO2 in MoOx powder. Subsequently, Mo4O11 grain growth densifies the targets. Excessive sintering temperature and pressure will cause the decomposition of Mo4O11, resulting in a decrease in density. Finally, the MoO2.623 target with a density of 97.85 % was obtained by hot pressing sintering with MoO2.494 as raw material at 973 K, 40 MPa, and holding temperature for 60 min. Raman mapping shows the MoO2.623 target with 16.9 wt% MoO2 and 83.1 wt% Mo4O11, and the phase distribution was uniform.

A dynamic phase separation model for glass transition behavior in water-triggered shape memory polymer towards programmable recovery onset

Water-triggered shape memory polymers (SMPs) have been extensively studied for biomedical applications due to their advantages of non-thermal actuation capability. However, few studies have been carried out to explore the working principle of shape recovery onset, which is essentially determined by the complex reactions between polymer macromolecules and water molecules. In this study, we developed a phase separation model to describe the dynamic glass transition in water-triggered SMPs. Based on the phase transition theory, dense and dilute phase separations of polymer macromolecules can be achieved when the dynamic diffusions of water molecules in the SMPs undergo dehydration and absorption processes, respectively. Then, the dynamic glass transition is resulted from the dehydration and absorption of water molecules, leading to the dense and dilute phases in the SMPs. Therefore, a free-energy equation has been developed to characterize the recovery onset, in which the mixing free energy and elastic free energy are originated from the Flory–Huggins solution theory and phase separation model, respectively. Moreover, the glass transition and its connection to shape recovery behaviors, i.e. recovery ratio, relaxation time and dynamic mechanical modulus, have also been investigated, according to the Fick’s diffusion law. Meanwhile, onset of programmable recovery has been explained by the dynamic phase separation, based on the transpiration theory and permeability model. Finally, the proposed model is verified using the experimental results reported in the literature. This study is expected to provide a fundamental approach to formulate the constitutive relationship between the dynamic phase separation and programmable recovery onset in the water-triggered SMPs.

Analysis of cementitious pore solutions with very high time resolution by coupling cross flow filtration and ICP-OES

Pore solution analysis is a powerful tool for understanding reactions that occur during the cement hydration. Crossflow filtration of cement paste provides more detailed insight into reactions and reaction pathways compared to standard methods for gaining pore fluid. In particular, the large time resolution for the analysis enables the characterization of fast processes like adsorption kinetics and hydration reactions of aluminate phases in unprecedented detail. A direct comparison of the crossflow filtration results with those obtained using a filter press showed no significant difference in pore solution composition. With this method, it is possible to analyze the complex reaction patterns of cementitious reactions in great detail during the first minutes of hydration. This is especially important for chemically admixed systems.

The computational molecular technology for complex reaction systems: The Red Moon approach

AbstractFor dealing with complex reaction (CR) systems that show typical chemical phenomena in molecular aggregation states, the Red Moon (RM) approach is introduced based on a new efficient and systematic RM methodology. First, the theoretical background with my motivation to develop the RM approach is presented from the recent necessity to perform ‘atomistic’ molecular simulation of large‐scale and long‐term phenomena of (i) complex chemical reactions, (ii) stereospecificity, and (iii) aggregation structures. The RM methodology uses both the molecular dynamics (MD) method for molecular motions (translation, rotation, and vibration of molecules) that frequently occur on a short‐time scale and the Monte Carlo (MC) method for rare events such as chemical reactions that hardly do on that time scale. Then, under the transition rate using both the potential energy difference before and after a rare event trial and its chemical kinetic probability, it is tested and judged by the MC method whether the trial is possible (Metropolis method). Next, typical applications of the RM approach are reviewed in two main research fields, (i) polymerization and (ii) storage battery (rechargeable battery or secondary cell), with various examples of our successful studies. Finally, we conclude that the RM approach using the RM methodology should become an efficient new‐generation approach as one promising computational molecular strategy (CMT). We believe it will play an essential role in surveying, at the multilevel resolution, various specificities of CR systems in molecular aggregation states.This article is categorized under: Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics Structure and Mechanism > Reaction Mechanisms and Catalysis Molecular and Statistical Mechanics > Molecular Dynamics and Monte‐Carlo Methods

Mitigation of testicular damage induced by DMBA/TPA through Murraya koenigii (L.) Spreng.: Insights into antioxidant and anti-apoptotic mechanisms

Abstract BACKGROUND: 7,12-Dimethylbenz[a]anthracene (DMBA) is a known mutagen, teratogen, and toxicant besides being a significant factor responsible for skin carcinogenesis. During carcinogenesis, DMBA and its metabolites produce excessive free radicals and oxidative stress. This oxidative stress further targets various cell organelles. Consequences of the damage by DMBA also influence vital organs, such as the brain, liver, and testis, with complex reactions, such as an increase in mutation, modification in cell membranes, structural proteins, metabolic enzymes, and signaling proteins. Therefore, this study evaluated the possible role of hydroethanolic Murraya koenigii (L.) Spreng. leaves extract (HEMKLE) upon damages incurred in testis tissues against DMBA/12-O-tetradecanoyl phorbol-13-acetate (TPA) in skin tumor-bearing mice. METHODS: Forty male LACA mice were segregated into four groups: control, DMBA/TPA, HEMKLE, and HEMKLE + DMBA/TPA. Skin tumors were induced by DMBA (500 nmol/100 μL of acetone) and TPA (1.7 nmol/100 μL of acetone; applied topically). RESULTS: The protective response of HEMKLE (200 mg/kg body weight) to testicular damage during skin tumorigenesis was apparent by recovery of endogenous antioxidant enzymes, along with histoarchitecture in the HEMKLE + DMBA/TPA group contrasted with the DMBA/TPA group. Furthermore, in the HEMKLE + DMBA/TPA group, reduced messenger ribonucleic acid and protein expressions of proapoptotic genes (caspase-9 and caspase-3) and enhancement in Bcl-2 were observed, proposing the anti-apoptotic potential of HEMKLE in testicular tissues. CONCLUSION: HEMKLE could be used as a nutraceutical or antioxidant drug to protect the body from testicular insults.

Patients After Mastectomy: The Prevalence of Phantom Breast Syndrome and Its Effect on Depression

Background: Phantom breast syndrome (PBS) following mastectomy has been believed to be a complex psychological reaction to mastectomy but studies on PBS are limited. The study aims to determine the prevalence of phantom breast syndrome and the impact of phantom breast syndrome on patients suffering from depression following mastectomy. Methods: A total of 272 women who had undergone mastectomy were interviewed using a structured questionnaire related to phantom breast sensation and depression caused by its effect by using ‘’Hamilton Depression Scale’. SPSS Statistics v27 was used to analyze the data. Results: Out of 272 females, 7.4% of the participants in our study reported having phantom sensations following surgery, 64.7% had Phantom Breast Syndrome,37.5% had mild, 5.1% had moderate, and 0.7% had severe depression according to ‘Hamilton Depression Scale’. Univariate logistic regression revealed that females under 45 have a higher likelihood of developing phantom breast syndrome compared to those over 45 (OR=2.012, p=0.038). Conclusion: Females with depression have a higher likelihood of experiencing phantom breast syndrome compared to females without depression.

IN ARTERIAL HYPERTENSION THE RIGHT VENTRICLE IS NO LONGER THE “FORGOTTEN CAVITY”

Objective: The right ventricle showed late interest in the assessment and stratification of the severity of arterial hypertension. The complex systemic reaction in the context of arterial hypertension, represented in particular by the activation of the renin angiotensin aldosterone system and the increase in sympathetic activity would suggest an early impairment of diastolic and later systolic function also of the right ventricle. Echocardiography is the most accessible way to evaluate the right ventricle in medical practice. Purpose of the study: to evaluate the precocity and the type of right ventricular function impairment in recently diagnosed hypertensive patients. Design and method: The patients were included after following the recommendations for the diagnosis of arterial hypertension according to the guide published by ESH in 2023. Personal biological data and parameters, cardiovascular risk factors, blood pressure values were recorded. Patients with other comorbidities, with secondary hypertension were excluded.Patients on antihypertensive treatment were also excluded. We investigated echocardiographically by analyzing 2D diastolic parameters, Doppler spectral and mitral and tricuspid tissue parameters as well as the global longitudinal strain of both ventricles. We studied right ventricle global longitudinal strain (RVGLS), septal wall longitudinal strain (RVSWLS), right ventricle lateral wall longitudinal strain (RVLWLS). Results: we studied a group of 61 patients who presented with essential hypertension, recently diagnosed, with an average age of 68.1 +- 6.3 years and who were analyzed according to grade, gender, risk factors. The (RVGLS) was analyzed separately and comparatively for the lateral and septal wall and the values were RVGLS =19%+- 3.2%. RVSWLS=-13.1% +-2.9% and RVFWLS=-22.6%+- 3.4%. The filling ratio of the right ventricle E/e’ was 14. Conclusions: the diastolic function of the right ventricle is affected in recently diagnosed hypertensive patients in relation to the degree of hypertension, myocardial mass and the filling ratio of the left ventricle. Slightly increased values of RVLWGLS could be interpreted as a consequence of sympathetic activation

Applicability and Validity of CFD‐based Compartment Models for One to Multiple Operating Points

AbstractCFD‐based compartment (CPT) models offer a promising modeling method and trade‐off between computational effort and required accuracy. The models combine the relevant fluid dynamics from the computational expensive CFD and the incorporation of complex reaction mechanisms usually used in basic reactor models. However, one criticism is their reliance on specific operating points, rendering them invalid when boundary conditions change. This study explores using a CFD‐based CPT model for static mixing elements across multiple operating points by making use of the creeping flow. The mean age theory facilitates a comprehensive comparison between CFD and CPT models. Results indicate that within this flow region, the CPT model can be extrapolated to other operating points via linear scaling.

Multi‐Interface Strategy for Electrode Tailoring Toward Fast‐Charging Lithium‐Ion Batteries

AbstractThick and dense graphite anodes used in lithium‐ion batteries (LIBs) suffer from sluggish reaction kinetics at the electrode level, causing Li metal plating on their surfaces and significant capacity decay at high charging currents. Thus, it is crucial to tailor electrodes based on a comprehensive understanding of the complex reaction kinetics to realize fast‐charging LIBs. A multi‐interface strategy is proposed for electrode tailoring using Al2O3 nanoparticles to enhance fast‐charging capability while suppressing Li metal plating. Molecular dynamics simulations suggest that the incorporated Al2O3 nanoparticles perturb the charge and molecule distributions in the boundary layer, forming an “interfacial highway” for facile Li+ transport at the Al2O3/electrolyte interface. This pushes Li+ deeper into the electrode and homogenizes the Li+ flux across the electrode's top surface. A full cell assembled with the Al2O3‐decorated graphite electrode (areal capacity of 4.4 mAh cm−2) exhibits excellent cyclability with a capacity retention of 83.4% over 500 cycles even at a 2C rate without any noticeable signal for undesirable Li plating. The role of interfacial highways predicted by theoretical computations is further validated using a pouch‐type full cell (500 mAh). These findings provide insights into the interfacial and microstructural design of high‐capacity graphite electrodes for fast‐charging, long‐cycling LIBs.

Психофизиологические особенности молодых людей с признаками интернет-зависимости

<p>The purpose of this work is to study the psychophysiological features and characteristics of the activity of the central nervous system in young people with signs of Internet addiction. Young people were investigated, students of grades 10-11 of Tyumen gymnasiums, as well as students of 1-3 courses of Tyumen State University were studied. Internet addiction was determined by the Chen test, the average screen time spent online using mobile gadgets was recorded, the level of anxiety was determined when modeling the symptom of network access cancellation. Cognitive plasticity was determined by the Stroop method. The properties of the central nervous system were studied using a Symbol Cancellation Test (Landolt rings), the critical frequency of the fusion of flickers, the time of simple and complex visual-motor reactions were measured. The following results were found: in gymnasium students with signs of Internet addiction, significant cognitive rigidity was recorded in congruent (1.19 ± 0.05 s per solution; p<0.01 with control) and non-congruent (1.49 ± 0.08 s per solution; p<0.001 with control) Scab samples, respectively. In the group with Internet addiction, low reliability of work on the Landolt test was also noted (Kp 16.24 ± 2.09%; p <0.001 with control), low accuracy of work (At 0.76 ± 0.03 units; p <0.001 with control) and more inert indicators of complex visual-motor reaction (436.66 ± 14.52 ms; p<0.001 with control).The most pronounced negative characteristics associated with low reliability of information processing, low endurance and ability to differentiate in the central nervous system, as well as reduced selective perception of information were noted in the group of gymnasium students and, in part, in the risk groups of gymnasium students and students.</p>

Real-Time Monitoring of Multistep Batch and Flow Synthesis Processes of a Key Intermediate of Lifitegrast by a Combined Spectrometer System with Both Near-Infrared and Raman Spectroscopies Coupled to Partial Least-Squares.

Process analytical technology (PAT) has been successfully applied in numerous chemical synthesis cases and is an important tool in pharmaceutical process research and development. PAT brings new methods and opportunities for the real-time monitoring of chemical processes. In multistep synthesis, real-time monitoring of the complex reaction mixtures is a significant challenge but provides an opportunity to enhance reaction understanding and control. In this study, a combined multichannel spectrometer system with both near-infrared and Raman spectroscopy was built, and calibration models were developed to quantify the desired products, intermediates, and impurities in real-time at multiple points along the synthetic pathway. The capabilities of the system have been demonstrated by operating dynamic experiments in both batch and continuous-flow processes. It represents a significant step forward in data-driven, multistep pharmaceutical ingredient synthesis.

Controlling the Selectivity of Electrocatalytic NO Reduction through pH and Potential Regulation on Single-Atom Catalysts.

Electrocatalytic nitrogen oxide reduction (NOxRR) emerges as an effective way to bring the disrupted nitrogen cycle back into balance. However, efficient and selective NOxRR is still challenging partly due to the complex reaction mechanism, which is influenced by experimental conditions such as pH and electrode potential. Here, we have studied the enzyme-inspired iron single-atom catalysts (Fe-N4-C) and identified that the selectivity roots in the first step of the nitric oxide reduction. Combining the constrained molecular dynamics (MD) simulations with the quasi-equilibrium approximation, the effects of electrode potential and pH on the reaction free energy were considered explicitly and predicted quantitatively. Systematic heat maps for selectivity between single-N and N-N-coupled products in a wide pH-potential space are further developed, which have reproduced the experimental observations of NOxRR. The approach presented in this study allows for a realistic simulation of the electrocatalytic interfaces and a quantitative evaluation of interfacial effects. Our results in this study provide valuable and straightforward guidance for selective NOx reduction toward desired products by precisely designing the experimental conditions.

Complex reaction mechanisms of electrolyte decomposition at large-scale Ni-rich Li-ion battery cells including electrode crosstalk effect

Ni-rich cathodes are essential for the advancement of high-energy lithium-ion batteries but encounter significant challenges at elevated voltages, including oxygen liberation and enhanced surface reactivity, which precipitate electrolyte decomposition. This study explores the intricate reaction mechanisms of electrolyte decomposition linked to the pronounced release of oxygen from the cathode lattice in large-scale 18650 cylindrical cells employing Ni-rich LiNi0.90Mn0.05Co0.05O2(NMC90)//graphite configurations, focusing on electrode crosstalk effects at high voltages. Notably, acetals such as methoxy methanol (49.93 %) and methane diol (50.07 %) were identified at 4.7 V, with their presence escalating at 4.9 V. Formaldehyde, present at 7.21 %, along with methanol (22.77 %), methane diol (36.35 %), and methoxy methanol (33.67 %), begins to manifest at 4.9 V. The dissolution of transition metals was analyzed using Inductively Coupled Plasma Atomic Emission Spectrometry, and changes in the double-layer capacitance were assessed through electrochemical impedance spectroscopy, further validating the link between these decomposition products and cathode failure associated with oxygen release. These insights reveal the complex relationship between electrolyte decomposition and cathode degradation due to oxygen release, highlighting a critical failure mechanism in large-scale cylindrical lithium-ion batteries.