Transition Rates Research Articles

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

A mathematical framework for analysing particle flow in a network with multiple pools.

In many real-world systems, the entry rate of particles into a lane is affected by the occupancy of nearby pools. For instance, in biological networks, the concentration of molecules on the side of a membrane affects the entry of particles through the membrane. To understand the behaviour of such networks, we develop a network model of ribosome flow models (RFMs) having multiple pools where each RFM captures the dynamics of particle flow in a lane and competes for the finite resources present at the nearby pool. We study a ribosome flow model network with two pools (RFMNTP) and show that the network always admits a steady state. We then analyse the behaviour of the RFMNTP with respect to modifying the transition rate through a theoretical framework. Simulations of the RFMNTP demonstrate a counterintuitive result. For example, increasing any of the transition rates in the presence of a slow site in an RFM can increase the output rate of some RFMs and decrease the output rate of the other RFMs simultaneously. This suggests that the role of local sharing of particles incorporated is non-trivial. Finally, we illustrate how these results can provide insights into studying a network with multiple pools.

Radiatively cooled magnetic reconnection experiments driven by pulsed power

We present evidence for strong radiative cooling in a pulsed-power-driven magnetic reconnection experiment. Two aluminum exploding wire arrays, driven by a 20 MA peak current, 300 ns rise time pulse from the Z machine (Sandia National Laboratories), generate strongly driven plasma flows (MA≈7) with anti-parallel magnetic fields, which form a reconnection layer (SL≈120) at the mid-plane. The net cooling rate far exceeds the Alfvénic transit rate (τcool−1/τA−1≫1), leading to strong cooling of the reconnection layer. We determine the advected magnetic field and flow velocity using inductive probes positioned in the inflow to the layer, and inflow ion density and temperature from analysis of visible emission spectroscopy. A sharp decrease in x-ray emission from the reconnection layer, measured using filtered diodes and time-gated x-ray imaging, provides evidence for strong cooling of the reconnection layer after its initial formation. X-ray images also show localized hotspots, regions of strong x-ray emission, with velocities comparable to the expected outflow velocity from the reconnection layer. These hotspots are consistent with plasmoids observed in 3D radiative resistive magnetohydrodynamic simulations of the experiment. X-ray spectroscopy further indicates that the hotspots have a temperature (170 eV) much higher than the bulk layer (≤75 eV) and inflow temperatures (about 2 eV) and that these hotspots generate the majority of the high-energy (>1 keV) emission.

Effect of COVID-19 on the Cultural Transition Towards the Use of Midwives Over Standard Doctors of Medicine [ID 2683504

INTRODUCTION: In recent times, the use of midwives as obstetrical providers has become increasingly popular within the United States. Unsurprisingly, the SARS-CoV-2 pandemic (COVID-19) had a large effect on societal trust of health care, including providers, and thus this study aimed to determine whether the pandemic further accelerated the cultural transition towards utilizing midwives as birth attendants. METHODS: Using the CDC Natality Database, we reviewed deliveries from 2016 to 2021 of previously healthy mothers, ages 18–35, with singleton pregnancies, measuring incidence of birth attendants including MDs, DOs, nursing midwives, and non-nursing midwives. A binomial model was used to perform logistic regressions to assess whether COVID-19 correlated with alterations in rates of transition of birthing attendants. RESULTS: Rates of deliveries attended by MDs declined at a greater extent, whereas births attended by DOs increased at a lesser rate, and nursing midwives and non-nursing midwives increased at a greater rate (change in rates pre-to-post COVID-19: −0.390%, −0.084%, 0.044%, and 0.204%, respectively; P<2.2×10−16). Although this rate of change was small, since the start of COVID-19 there has been an 11% increase in non-MD-attended deliveries, nearly double the rate seen prior. CONCLUSION: There has been a significant increase in the number of deliveries attended by DOs, nursing midwives, and non-nursing midwives over the past several decades, even more so since the start of COVID-19. With the transition in the utilization of health care professionals, further investigation needs to be conducted to assess the effects this has on health outcomes of the mother and infant.

Can process intensification of liquefaction technology for LNG and LH2 accelerate adoption for transportation use?

One of the reasons gaseous fuels, methane, and hydrogen, are renewable and sustainable replacements for traditional liquid hydrocarbon-based transportation fuels is their small carbon footprint. Global awareness of the immediate need to address impacts of emissions from transportation energy use has emphasized urgency of changes from business as usual. However, the transition from existing fuels to new fuels is complex because fuel usage is huge, and so many variables influence the rate of adoption. When one reads excellent energy outlooks of major energy companies, data driven reports of international and national energy agencies, along with thoughtful studies of the water, energy, food nexus, the systemic complexities are daunting. Marchetti’s insightful numerical modeling of the rate of transition among different energy sources over the past two centuries with credible validation from recorded usage data shows the time scale for appreciable changes among energy systems is several decades. A further important observation of Marchetti’s work is that transitions among energy sources were and are driven by substitution of superior technology rather than by depletion of prevalent sources. These observations incentivize developments of more efficient, less expensive, robust, scalable methods of production, liquefaction, storage, transport, delivery, and dispensing of hydrogen and natural gas to accelerate adoption by transportation customers. This paper presents a few examples of process intensification in advanced liquefiers for LNG and LH2 at the same location could reduce capital costs, energy costs, and footprints of different sized liquefiers. These combinations could help address gaps in existing technology for several essential needs such as liquefiers for heavy-duty vehicle refueling stations or marine vessel bunkering systems, or refrigerators for storage tank boil-off management systems. Modular, containerized liquefiers plants with several tonne/day capacity could be scaled by interconnecting multiple units to make small industrial plants that match localized fuel demands from distributed mobile users.

The Shear-Accelerated II-I Phase Transition of Isotactic Poly(1-Butene).

The II-I phase transition of isotactic poly(1-butene) (iPBu) leads to improved mechanical performance. However, this will take several weeks and increase storage and processing costs. In this work, shear forces are introduced into the supercooled iPBu melt, and the effects of isothermal crystallization temperature (Tc) and shear temperature (Tshear) on crystallization and phase transition are explored. Shear-induced transcrystalline morphology of Form II with a significantly shortened crystallization induction period can beobserved at relatively high Tc (105 °C). Besides, the shear-induced Form II can transit to Form I faster than the unsheared one. In addition, the phase transition rate increases as the Tshear decreases, with the fastest rate occurring at Tshear of 120 °C. The half transition time (t1/2) is measured as 6.3 h when Tc = 105 °C, Tshear = 120 °C, which is much shorter than the 20.7 h required for unsheared samples. The accelerated phase transition of iPBu can be attributed to the stretching of molecular chains, resulting from shear treatment. This study provides a quantitative analysis of the influence of the shear treatment and the Tshear on the II-I phase transition rate. It also presents a cost-effective and straightforward approach for expediting the phase transition process.

Collisional-radiative modeling for the EUV spectrum of W40+-W42+ions

The wavelengths and transition rates of W40+-W42+ ions within the range of 40–140 Å, have been calculated using the Flexible Atomic Code of the Dirac-Fock-Slater method with a central potential. We investigated the charge state distribution of W38+-W45+ ions at different temperatures by constructing an appropriate rate equation and demonstrate the importance of the dielectronic recombination process. Additionally, we simulated the emission spectra of W40+-W42+ ions in a Tokamak plasma environment using collisional-radiative modeling. Our findings demonstrate strong agreement with experimental results and other related theoretical investigations. Finally, we propose certain pairs of transition lines as diagnostic tools for plasma temperature and density, leveraging the correlation between line intensity ratio and electron temperature and density.

Labour market trajectories and unemployment of older workers in Europe after the Great Recession

AbstractMany European countries want to overcome the early exit from labour market which was widespread since the 1970s through pension reform and labour policies. The extension of working life is hindered by factors that the literature overlooks. This article focuses on the discontinuity of the late‐career caused by unemployment. The aim is to investigate whether older workers are at risk of unemployment and what are the transitions after spells of unemployment. The labour market trajectories of workers over 50s in 11 European countries from 2006 to 2019 were analysed, specifically after the Great Recession and before the Covid‐19 epidemic. It is based on longitudinal survey data from the generated Survey of Health, Ageing and Retirement in Europe Job Episodes Panel. Event history analysis and sequence analysis were performed. Older employees are unlikely to face unemployment. The transition rate highlights the difficulty for older workers into re‐employment. A low education level increases the risk of unemployment and remaining unemployed. Data by country confirm the trend towards overcoming the transition from unemployment to early exit. Divergences concern the higher risk of being trapped in unemployment in Southern European countries such as Greece and Italy.

Optical transition properties, 1550-to-980 nm upconversion, and temperature sensing of NaEr(WO4)2:Yb3+ phosphors synthesized via the microwave-assisted hydrothermal method

Improving photoelectric conversion efficiency and enhancing heat management are two critical considerations for silicon-based solar cells. In this study, efficient Yb3+ infrared emissions through the upconversion process were achieved by adjusting the concentrations of Yb3+ in Er3+ highly condensed NaEr(WO4)2 phosphor. Additionally, the temperature sensing based on the fluorescence intensity ratio (FIR) was also studied in this tungstate system. Moreover, the radiative transition rates for all relevant transitions of Er3+ in NaEr(WO4)2:Yb3+ phosphors were calculated in the framework of Judd-Ofelt theory, and the optical transition properties of Yb3+ were also revealed by taking Er3+ as a reference. It was found that the radiative transition rate of Yb3+:2F5/2→2F7/2 (2977.52s−1) is significantly higher than that of Er3+:4I11/2→4I15/2 (303.50s−1), thus suggesting the feasibility for the strong emission at 980 nm of Yb3+ in assistance of the energy transfer 4I11/2+2F7/2→4I15/2+2F5/2. Finally, strong and nearly pure NIR emissions of Yb3+ were experimentally observed under 1550 nm excitation, and possible upconversion mechanisms were proposed. The temperature sensing performance of the studied materials was also assessed. All the results imply that NaEr(WO4)2:Yb3+ constitutes an excellent material for enhancing both the photoelectric conversion efficiency and thermal management of silicon-based solar cells.

Metro Train Stopping Scheme Decision Based on Multisource Data in Express-Local Train Mode

Metro Train Stopping Scheme Decision Based on Multisource Data in Express-Local Train Mode

Оценка предельно допустимых концентраций тяжелых металлов в почвах с учетом взаимосвязей свойств почв

It has been proved in the work that admissible concentration limits of mobile fraction of heavy metals in the soils have to be additionally rated for the water- soluble fractions taking into consideration the rate of the ion transition into solution and soil deposit capacity, with respect to environment pH, as pH = 4,8 in the CH3COONH4 exudate basically does not appear in the soils. The admissible concentration limits have to be assessed due to the soil characteristics combination which determines heavily the concentration of heavy metal water-soluble fractions (efficient solubility of their deposits, effective constants of the ion exchange and effective constants of the complex instability). The correlation of water-soluble fractions of heavy metals depending on pH in the common black soils was: for Pb = -0,40; for Cd = -0,32; for Co = -0,39; for Ni = -0,47. The proportion of positively charged species not linked into complexes increases under the pollution augment in the soil. This way, PbL7PbL+ ratio was 0,33±0,01 in the check, under the pollution it was Pb - 0,08±0,01. The feedback systems on photosynthesis activity, sprout development, microbial flora change, genetic tests on drosophila are offered for the assessment of the heavy metal influence over the biotests. Keywords: HEAVY METALS, ADMISSIBLE CONCENTRATION LIMITS, BIOTESTS

Do MNEs Create Spillover Effects in Cuba?

In the past three decades, Cuba has extended opportunities for Multinational Enterprises (MNEs) to establish operations within its predominantly centrally planned economy. Many MNEs have seized this opportunity and established their presence in Cuba, resulting in FDI inflows reaching up to 2 per cent of GDP in certain years. In our paper, we aim to assess the impact of MNEs’ activity on local companies, with a specific focus on productivity spillover effects. Additionally, we analyze how institutional factors influence the strength of these effects. Our data collection involved conducting questionnaires and semi-structured interviews with MNEs operating in Cuba and experts on the Cuban economy. Our findings reveal that MNEs introduce new technology and knowledge to Cuba, thereby positively influencing the local development. We have confirmed the existence of vertical spillover effects, as certain MNEs provide direct assistance to local companies with whom they collaborate. The extent of these spillover effects is heavily contingent on Cuba’s institutional framework. Local regulations mandate that MNEs cooperate with local companies for various operations, such as expanding product distribution across the country, thus amplifying the impact. Conversely, spillover effects through labor mobility are limited, as there is a low rate of transition from MNEs to local companies among the local workforce. Stringent legal constraints further hinder interaction between MNEs and the Cuban private sector, thereby limiting the broader spillover effects.

The study of atomic structure parameters of n = 2-n = 3 for Cl XII ion

This study utilized the multiconfiguration Dirac-Hartree-Fock (MCDHF) method to compute transition wavelengths among the 2s22p2, 2s22p3s, 2s22p3d, 2s2p23p configurations of the carbon-like Cl ion, as the same time, the transition rates, weighted oscillator strengths, and line strengths for these transitions are investigated. Comparison with experimental and theoretical results demonstrated favorable agreement, validating the accuracy of the calculated results. The study's results for transition rates deviated by no more than 20 % from reference values and showed good agreement for weighted oscillator strengths compared to Hartree-Fock Relativistic (HFR) method calculations. The line strength results served to assess the reliability of the calculated atomic structure parameters. We hope these results are anticipated to contribute to the expansion of the Cl ions database and furnish valuable help for studies within the plasma domain.

Analysis of the characteristics of silver nanowires (AgNW) random network for transparent heater applications

Transparent heaters (THs) find widespread application in various indoor and outdoor settings, such as LCD panels and motorcycle helmet visors. Among the materials used for efficient TH performance, the AgNW network stands out due to its high conductivity, substantial transmittance, and minimal solution requirement. Extensive research has been directed towards enhancing AgNW characteristics, focusing on smaller diameters and longer wires. In TH applications, the primary considerations include a rapid response and elevated temperature. Consequently, this research delves into investigating the impact of parameters like diameter, length, and density on random AgNW networks under varying applied voltages. The finite element method is employed for analyzing temperature changes in response to voltage application, particularly in scenarios involving small-scale setups with high-density and high-percolation AgNW networks. The results reveal a significant increase in the thermal transition rate, ranging from 28% to 36%, with varying densities in the random network. Within the same density, the AgNW network with larger diameters and lengths demonstrates the highest temperatures, aligning with previous calculations. Furthermore, a trade-off exists between optical properties in smaller diameters and electrical properties in larger diameters within a relatively narrow temperature range.

Resonant detectors of gravitational wave in the linear and quadratic generalized uncertainty principle framework

In this work, we consider a resonant bar detector of gravitational waves in the generalized uncertainty principle (GUP) framework with linear and quadratic momentum uncertainties. The phonon modes in these detectors vibrate due to the interaction with the incoming gravitational wave. In this uncertainty principle framework, we calculate the resonant frequencies and transition rates induced by the incoming gravitational waves on these detectors. We observe that the energy eigenstates and the eigenvalues get modified by the GUP parameters. We also observe non-vanishing transition probabilities between two adjacent energy levels due to the existence of the linear order momentum correction in the generalized uncertainty relation which was not present in the quadratic GUP analysis (Class Quantum Gravity 37:195006, 2020). We finally obtain bounds on the dimensionless GUP parameters using the form of the transition rates obtained during this analysis.

Exponential stability for switched semi‐Markov jump systems with mode‐dependent average dwell time and generally uncertain transition rates

AbstractThis paper investigates the exponential stability in mean square sense for a class of stochastic switched semi‐Markov jump systems (ssSMJS). In this model, a hierarchical control switched regulation is designed, considering the external stochastic disturbances and generally uncertain transition rates (TRs) of the entire system and making the system more general and practical. By using appropriate Lyapunov–Krasovskii functional, linear matrix inequality, Jensen inequality, and mode‐dependent average dwell time (MDADT), sufficient conditions on the exponential stability in mean square sense for ssSMJS are derived. Furthermore, a nonfragile state feedback controller is designed. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed criterion.

Multi-Temporal Analysis of the Impact of Summer Forest Dynamics on Urban Heat Island Effect in Yan’an City

In this study, MODIS land products and China land cover datasets were used to extract normalized difference vegetation index, land surface temperature, and vegetation cover type in Yan’an City during the summers of 2017–2022. On this basis, analysis of spatial change and correlation were carried out as a way to study the mitigation effect on urban heat islands in Yan’an City with forest. The study showed that: (1) The coverage of normalized difference vegetation index over 0.4 in summer in Yan’an City increased from 59.38% to 69.12%, and the vegetation showed good growth conditions. It has a spatial distribution pattern of more in the south and less in the north. (2) The proportion of the urban heat island in Yan’an City increased from 15.51% to 16.86%. Urban heat island intensity fluctuated year by year, with the maximum urban heat island intensity of 6.26 °C appearing in 2019. It has a spatial distribution pattern of less in the south and less in the north. The transition rate of temperature field grade from low to high is 73.32%, and the transition rate to low is only 0.31%. (3) There is a negative correlation between land surface temperature and normalized difference vegetation index in Yan’an City. Vegetation has a mitigating effect on the UHI and the best cooling effect among the vegetation is shown by forest. The cooling effect of forest in Yan’an City is attenuated by an increase in distance, and the effective range is greater than 1000 m. In this study, the regulation effect of forest on the urban heat island was obtained by digging deeper into the intrinsic connection between spatial change in vegetation cover and land surface temperature change in Yan’an City. It provides an important reference for the formulation of meteorological protection policy as well as the promotion of sustainable development of the urban ecological environment and is of guiding significance for future urban planning and ecological construction.

Clinical and neurodevelopmental predictors of psychotic disorders in children and adolescents at clinical high risk for psychosis: the CAPRIS study.

The neurodevelopmental hypothesis of schizophrenia represents the disorder as an expression of an alteration during the brain development process early in life. Neurodevelopmental variables could become a trait marker, and the study of these variables in children and adolescents at clinical high risk for psychosis (CHR) could identify a specific cluster of patients who later developed psychosis. The aim of this study is to describe clinical and neurodevelopment predictors of transition to psychosis in child and adolescent participants at CHR.Naturalistic longitudinal two-center study of 101 CHR and 110 healthy controls (HC) aged 10-17. CHR participants were children and adolescents aged 10-17, meeting one or more of the CHR criteria assessed at baseline and at 18 months' follow-up. Neurodevelopmental variables assessed were obstetric complications, delay in principal development milestones, and presence of a neurodevelopment diagnosis. Pairwise comparisons, linear regressions, and binary logistic regression were performed.A transition rate of 23.3% at 1.5 years was observed. Participants who developed psychosis (CHR-P) showed higher rates of grandiosity and higher proportions of antipsychotic medication intake at baseline compared to participants who did not develop a psychotic disorder (CHR-NP). In terms of neurodevelopment alterations, CHR-P group showed a higher proportion of participants reporting delay in language development than the CHR-NP and HC groups. The odds of psychosis increased by 6.238 CI 95% [1.276-30.492] for a one-unit increase in having a positive score in grandiosity; they increased by 4.257 95% CI [1.293-14.023] for a one-unit increase in taking antipsychotic medication, and by 4.522 95% [1.185-64.180] for showing language development delay. However, the p-values did not reach significance after adjusting for multiple comparisons.A combination of clinical and neurodevelopmental alterations could help predict the transition to psychotic disorder in a CHR child and adolescent sample. Our results suggest the potential utility of collecting information about neurodevelopment and using these variable multifactorial models to predict psychosis disorders.

Soret and Dufour effects on an unsteady MHD flow about a permeable rotating vertical cone with variable fluid properties

The objective of the present work is to examine the characteristics of unsteady incompressible magnetohydrodynamic fluid flow around a permeable rotating vertical cone. The effects of thermal radiation, viscous dissipation, and the Soret and Dufour effects are investigated in the analysis of heat and mass transfer. The viscosity of the fluid is considered inversely proportional to the temperature, and the thermal conductivity of the fluid is considered directly proportional to the temper-ature. The governing equations are converted into ordinary differential equations using suitable similarity transformations, which are then solved numerically using bvp4c from MATLAB. Results obtained in this study are in excellent correlation with previously conducted studies. The results demonstrate that the Dufour and Soret effects subsequently reduce the heat transit rate (by –3.3%) and mass transit rate (by –1.2%) of the system. It is also detected that fluids with higher viscosity tend to increase tangential skin friction (+8.9%) and azimuthal skin friction (+8.3%). The heat transit rate of the system is found to be more efficient for fluids with higher viscosity and lower thermal conductivity and Eckert numbers. Further-more, the thickness of the momentum, thermal, and concentration boundary layers significantly reduces while the heat and mass transit rates (+17.8% and +18.3%, respectively) of the system become more efficient for greater values of the un-steadiness parameter.

Effects of a Larger N‐Heterocyclic Ring in Rofecoxib Analogues on AIE Activity and Multifunctional Applications

AbstractTwo analogues of rofecoxib, 2‐Pyr‐ROF and 2‐Pip‐ROF, were designed according to the strategy of heterocyclic ring enlargement and facilely synthesized in a facile manner by Knoevenagel reactions. The first compound, 2‐Pyr‐ROF, had low quantum yields (QY) of 3.0 % in the solid states. After replacing the pyrrolidinyl with piperidinyl, the resulting 2‐Pip‐ROF had a significantly increased QY, with a value of 28 %. The root‐mean‐square deviation (RMSD) values between S0 and S1 of 2‐Pyr‐ROF and 2‐Pip‐ROF in tetrahydrofuran were 0.51, 0.35 Å, respectively. As compared with 2‐Pyr‐ROF, compound 2‐Pip‐ROF exhibited a smaller RMSD, which indicated a lower non‐radiative transition rate. A single‐crystal X‐ray diffraction study and Hirshfeld surfaces analysis revealed that 2‐Pip‐ROF had a more nonplanar molecule structure and a weaker π‐π interaction, which might result in a higher fluorescence intensity and QY. Owing to its better aggregation‐induced emission (AIE) behavior, compound 2‐Pip‐ROF showed more multi‐functional applications, including mechanochromism, acidochromism, and lipid droplets imaging ability. These results imply that the strategy of heterocyclic ring enlargement provides a new paradigm for the design of new luminogens with AIE properties.