Rate Acceleration Research Articles

Active Locating Exciton- and Charge-Initialized Degradation in Quantum-Dot Light-Emitting Diodes.

For quantum-dot light-emitting diodes (QLED), electrical aging commonly introduces collective aging sources across all layers, making it difficult to isolate the impact of each layer on electroluminescence (EL) degradation. In this work, a layer-selective aging method using active photoexcitation is proposed, in which the photoexcitation wavelength is used to selectively target specific layers for exciton generation, and an electrical bias is applied to induce photocurrent and create charges. An iterative aging-sampling (A-S) procedure is used to link aging conditions to EL degradation. It is found that photo-aging leads to strong but reversible quenching of EL intensity, which is interpreted as being caused by electrical field screening due to trapped charges in the quantum dot (QD) layer and requires electrical activation before the sampling (S) step. Repeated A-S cycles in a model red QLED system show that excitations in the QD layer result in negligible EL degradation. In contrast, aging of the hole-transport (HT) layer enables an acceleration of aging rate by 3 orders of magnitude compared to standard aging and is interpreted as a result of photo-charge accumulation in the HT layer, particularly related to electrons and low electron mobility.

Spectroscopic and Computational Insights into the Mechanism of Cofactor Cobalt-Carbon Bond Homolysis by the Adenosylcobalamin-Dependent Enzyme Ethanolamine Ammonia-Lyase.

The adenosylcobalamin (AdoCbl)-dependent enzyme ethanolamine ammonia-lyase (EAL) catalyzes the conversion of ethanolamine to acetaldehyde and ammonia. As is the case for all AdoCbl-dependent isomerases, the catalytic cycle of EAL is initiated by homolytic cleavage of the cofactor's Co-C bond, producing CoIIcobalamin (CoIICbl) and an adenosyl radical that serves to abstract a hydrogen atom from the substrate. Remarkably, in the presence of substrate, the rate of Co-C bond homolysis of enzyme-bound AdoCbl is increased by 12 orders of magnitude. For Class I AdoCbl-dependent isomerases, an important contribution to this rate acceleration stems from a stabilization of the CoIICbl posthomolysis product by the axially coordinated histidine residue that displaces the pendant base from the Co ion upon AdoCbl binding to these enzymes. However, EAL and other Class II isomerases bind AdoCbl in the so-called "base-on" conformation and must therefore employ a different mechanism of Co-C bond activation. In the present study, we have used a combined spectroscopic and computational approach to probe the conformational changes and enzyme/cofactor/substrate interactions that contribute to the rate acceleration of Co-C bond homolysis in EAL. Spectroscopic data of AdoCbl and CoIICbl show minimal perturbations upon cofactor binding to EAL in both the absence and presence of substrate. Structural models of free and EAL-bound AdoCbl were constructed using molecular dynamics and quantum mechanics/molecular mechanics computations. By carrying out relaxed potential energy scans for Co-C bond cleavage of free and EAL-bound AdoCbl, we identified key cofactor/enzyme interactions that contribute to the Co-C bond activation by EAL and obtained Co-C bond dissociation energies that agree well with published experimental data.

Reasons for accelerating inflation in the Russian economy

The article shows that the increase in inflation in 2020—2024 is associated with the acceleration of the growth rate of the money supply. The main contribution to the growth of the monetary base was made by transactions with the National Wealth Fund, which were not sterilized. Following this, there was an acceleration in the growth rate of lending, supported by preferential programs and a decrease in the required reserve ratio, which was reflected in an increase in the credit multiplier. Accelerated growth in the money supply led to an increase in the growth rate of consumer prices. The current phase of the economic cycle, together with the labor shortage, is increasing inflationary pressure. Inflation growth could have been even greater if not for the increased demand for real cash balances and high rates of real GDP growth in 2023—2024. Along with a tight monetary policy, additional measures to reduce inflation may include slower indexation of regulated prices and excise rates; limiting the growth rate of the consumer and auto loan portfolio of commercial banks; increasing reserve requirements for them.

Crashworthiness analysis of a novel corrugated multi-cellular tube structure

This study innovatively combines Fourier curves with circular tube design and proposes a novel corrugated multi-cellular tube structure (NCMTS), aiming to improve crashworthiness. The accuracy of the finite element model was validated through axial quasi-static compression tests. The influence mechanism of different structural parameter combinations on the energy absorption capacity of NCMTS was further investigated. The results reveal that the EA of NCMTS increases monotonically with rising of parameter ru , with a notable acceleration in growth rate as parameter Rc is elevated. Notably, the combination of larger values of ru and Rc , and tout and tc can significantly improve the crashworthiness performance. Moreover, appropriately increasing C 1 and C can increase the EA of NCMTS by approximately 50%. Through multi-objective optimization analysis utilizing the global response surface method, the optimal structural parameters for NCMTS were identified: at Rc = 0.68, C = −0.57, C 1 = 0.16, tout = 2.0 mm, tc = 0.68, the EA, SEA and IPCF reached 7.02 kJ, 15.33 kJ/kg and 400 kN respectively. This study offers valuable guidance for the design and optimization of high-performance collision energy-absorbing structures.

Influence of Sudden Changes in Foot Strikes on Loading Rate Variability in Runners.

Foot strike patterns influence vertical loading rates during running. Running retraining interventions often include switching to a new foot strike pattern. Sudden changes in the foot strike pattern may be uncomfortable and may lead to higher step-to-step variability. This study evaluated the effects of running with an imposed and usual foot strike on vertical loading rate variability and amplitude. Twenty-seven participants (16 men and 11 women; age range: 18-30 years) ran on an instrumented treadmill with their usual foot strike for 10 min. Then, the participants were instructed to run with an unusual foot strike for 6 min. We calculated the vertical instantaneous and vertical average loading rates and their variances over 200 steps to quantify vertical loading rate variability. We also calculated the amplitude and variability of the shank acceleration peak using an inertial measurement unit. The vertical loading rate and shank acceleration peak amplitudes were higher when running with a rearfoot strike, regardless of the foot strike conditions (i.e., usual or imposed). The vertical loading rate and shank acceleration peak variability were higher when running with an imposed rearfoot strike than when running with a usual forefoot strike. No differences were found in the vertical loading rate and shank acceleration peak variabilities between the imposed forefoot strike and usual rearfoot strike conditions. This study offers compelling evidence that adopting an imposed (i.e., unusual) rearfoot strike amplifies loading rate and shank acceleration peak variabilities.

Temperature Margin Calculation During Finite Element Creep Simulations

Abstract Creep deformation in turbomachinery applications is a highly nonlinear phenomenon where ±15 °C may halve or double the average rupture life. Even in well-controlled laboratory conditions, this stochastic nature means that identical tests may differ by a factor of two. Analysts using implicit finite element user creep subroutines may not appreciate the uncertainty of their solution, or the design changes required to account for uncertainty in either the boundary conditions or the solution itself. Designing to a maximum strain limit does not consider the sudden acceleration of tertiary creep rates. Applying a time factor may extend the simulation time by multiple factors. This paper presents a methodology where two estimations of creep damage are made in parallel to the creep simulation at actual operating temperatures. These two estimations consider the predicted change in stress relaxation, at higher or lower temperatures, to estimate the temperature change required to reach the onset of creep, at any given node in the model, and at any given time in the analysis. This margin calculation is expanded to consider the uncertainty in creep prediction. A time-based scatter factor is incorporated into the temperature margin calculation to provide a minimum temperature margin that includes model uncertainty. The analyst can also consider the uncertainty of the temperature prediction and boundary conditions to produce a robust creep prediction in a real-world simulation. The methodology is validated through the finite element analysis (FEA) of example cases and applied to a creep-limited second stage turbine blade.

Acceleration of Chronic Wound Healing With Galenic cream of Snail Seromucoid, Durian Peel Extract Polysaccharides And chitosan

The treatment of chronic wounds take a relatively long time so a wound care process or wound management using traditional or modern medical therapy is needed. Objective: The objective of this study is to investigate the effectiveness of galenic cream of snail seromucoid, durian peel extract and chitosan as anti-inflammatories in vitro and in vivo for chronic wound healing. Theoretical Framework: Snail seromucoid, durian peel extract, and chitosan and their combinations can be developed as galenic cream preparations for the treatment of chronic wounds Method: The research method was based on the experimental design with the research stages covering bioformulation of galenic cream preparations of snail seromucoid, durian peel extract, and chitosan as well as testing the quality of galenic preparations physically, chemically, and microbiologically. Results and Discussion: Bioformulation galenic preparation of 2% snail seromucoid, 2% polysaccharide of durian peel extract; 2% chitosan and their combination with ratio 1:1:1 according to the requirements of Food and Drug Monitoring Agency, Republic of Indonesia No. 32 of 2019, it meets the requirements for the quality test of cream preparations in a physicochemical manner including pH, antioxidant activity, dispersion, and adhesion and microbiologically includes Total Plate Number, Yeast Mold Number, and no microbial pathogens Staphylococcus aureus, Pseudomonas aeruginosa,and Candida albicans. Research Implications: The galenic of 2% snail seromucoid, 2% polysaccharide of durian peel extract and 2% chitosan 2% is effective as an anti-inflammatory cream. The results of this study indicate implications for the acceleration of chronic wound healing rates. Originality/Value: Harti et al's research results of the Basic Research Program Higher Education, Ministry of Research and Technology Republic of Indonesia, 2019-2022 fiscal years and the Simple Patent No. S00202010479 showed a synergistic effect of bioactive compounds seromucoid snails and chitosan as biological response modifiers or bioimmunostimulators and antimicrobial agents so that it can be developed as anti-inflammatory galenic preparations

Inadvertent neuromodulation during pulmonary vein isolation for atrial fibrillation – immediate and short-term effects of radiofrequency and cryogenic energy

Inadvertent vagal denervation has been reported as an adjunctive effect during pulmonary vein isolation (PVI) for atrial fibrillation (AF). However, it is not known how frequent and durable this effect is during thermal ablation. Material and methods: This is a retrospective study of consecutive patients with AF and first PVI in sinus rhythm using radiofrequency or cryogenic energy. We studied the incidence of non-targeted and non-transient heart rate (HR) acceleration, induction and abolition of vagal reflex (VR), as well as the durability of the HR increase at the end of the first month. Results: PVI was carried out in 102 patients (cryo, n = 46). Overall, 60 patients (58.8%) had inadvertent neuromodulation, presented by VR induction and abolition (n = 18, 17.6%) and predominantly by HR increase (n = 50, 49%). In patients with vs those without HR acceleration the mean HR increase at the end of the procedure was 14.2 ± 5.64 bpm vs. -2.63 ± 5.43 bpm, and at the next day – 10.6 ± 7.53 bpm vs. 3.68 ± 7.75 bpm (p < 0.001 for all). The mean HR at 1 month was 74.2 ± 9.91 bpm vs. 68.9 ± 12 bpm (p = 0.048). Patients with a durable HR increase were younger (median age 61 vs. 65.5 years, p = 0.016) and less frequently had heart failure with reduced ejection fraction (1% vs. 6.9%, p = 0.031). Conclusion: Inadvertent neu-romodulation occurs in more than half of the patients with radiofrequency or cryo PVI for AF. It is mostly represented by a HR increase and persists for up to at least one month post-procedurally.

The identification of extensive samples of motor units in human muscles reveals diverse effects of neuromodulatory inputs on the rate coding.

Movements are performed by motoneurons transforming synaptic inputs into an activation signal that controls muscle force. The control signal emerges from interactions between ionotropic and neuromodulatory inputs to motoneurons. Critically, these interactions vary across motoneuron pools and differ between muscles. To provide the most comprehensive framework to date of motor unit activity during isometric contractions, we identified the firing activity of extensive samples of motor units in the tibialis anterior (129 ± 44 per participant; n=8) and the vastus lateralis (130 ± 63 per participant; n=8) muscles during isometric contractions of up to 80% of maximal force. From this unique dataset, the rate coding of each motor unit was characterised as the relation between its instantaneous firing rate and the applied force, with the assumption that the linear increase in isometric force reflects a proportional increase in the net synaptic excitatory inputs received by the motoneuron. This relation was characterised with a natural logarithm function that comprised two stages. The initial stage was marked by a steep acceleration of firing rate, which was greater for low- than medium- and high-threshold motor units. The second stage comprised a linear increase in firing rate, which was greater for high- than medium- and low-threshold motor units. Changes in firing rate were largely non-linear during the ramp-up and ramp-down phases of the task, but with significant prolonged firing activity only evident for medium-threshold motor units. Contrary to what is usually assumed, our results demonstrate that the firing rate of each motor unit can follow a large variety of trends with force across the pool. From a neural control perspective, these findings indicate how motor unit pools use gain control to transform inputs with limited bandwidths into an intended muscle force.

The identification of extensive samples of motor units in human muscles reveals diverse effects of neuromodulatory inputs on the rate coding

Movements are performed by motoneurons transforming synaptic inputs into an activation signal that controls muscle force. The control signal emerges from interactions between ionotropic and neuromodulatory inputs to motoneurons. Critically, these interactions vary across motoneuron pools and differ between muscles. To provide the most comprehensive framework to date of motor unit activity during isometric contractions, we identified the firing activity of extensive samples of motor units in the tibialis anterior (129 ± 44 per participant; n=8) and the vastus lateralis (130 ± 63 per participant; n=8) muscles during isometric contractions of up to 80% of maximal force. From this unique dataset, the rate coding of each motor unit was characterised as the relation between its instantaneous firing rate and the applied force, with the assumption that the linear increase in isometric force reflects a proportional increase in the net synaptic excitatory inputs received by the motoneuron. This relation was characterised with a natural logarithm function that comprised two stages. The initial stage was marked by a steep acceleration of firing rate, which was greater for low- than medium- and high-threshold motor units. The second stage comprised a linear increase in firing rate, which was greater for high- than medium- and low-threshold motor units. Changes in firing rate were largely non-linear during the ramp-up and ramp-down phases of the task, but with significant prolonged firing activity only evident for medium-threshold motor units. Contrary to what is usually assumed, our results demonstrate that the firing rate of each motor unit can follow a large variety of trends with force across the pool. From a neural control perspective, these findings indicate how motor unit pools use gain control to transform inputs with limited bandwidths into an intended muscle force.

Modeling and Simulation of Fatigue Crack Initiation Process Based on Field Theory of Multiscale Plasticity (FTMP): Part II: Modeling Vacancy Formation and Coupling with Diffusion Analysis

Cyclic straining simulations using incompatibility-incorporated crystal plasticity-FEM, which exhibit PSB ladder structure evolutions as detailed in Part I, are coupled with diffusion analyses of produced vacancies. A new vacancy source model is introduced based on the Field Theory of Multiscale Plasticity (FTMP), interpreting the relationship between the incompatibility rate and the flux of dislocation density as edge dipole annihilation processes. Both direct and indirect coupling diffusion analyses, with and without cyclic straining, demonstrate that varying incompatibility rates tend to further promote vacancy diffusion, leading to surface grooving, enhanced extension rates, and eventual transition to cracks. The findings reveal that (i) the evolved PSB ladder structure serves as a site for vacancy formation, (ii) it provides a diffusion path toward the specimen surface, and (iii) it significantly enhances groove extension rates. These factors effectively facilitate the transition from a “groove” to a “crack”, evidenced by the abrupt acceleration of the extension rate, mirroring systematic experimental observations. These achievements validate the FTMP’s capability to simulate complex phenomena and significantly deepen our understanding of slip band–fatigue crack transition mechanisms.

Synthesis of 3-Substituted Indoles by Yonemitsu Three-Component Reactions Accelerated in Microdroplet/Thin Film.

3-Substituted indoles are an important framework of many drugs, agricultural chemicals, functional materials, and bioactive compounds. Malononitrile-based three-component Yonemitsu reactions are attractive choices for the synthesis of 3-substituted indole derivatives but suffered from long reaction time and harsh conditions (e.g., elevated temperature and special catalysts/solvents) in conventional conversions. In this study, we developed a metal-free, efficient, mild, and wide microdroplet/thin-film method to construct 18 3-substituted indoles from various substituted aromatic aldehydes and indoles with good reaction yields (42-69%) and fantastic reaction acceleration (1.32 × 103 rate acceleration factor relative to the bulk reaction). By spraying 0.8 mol L-1 reactants at 300 μL min-1, the rate of the microdroplet/thin film product was scaled up to 1.72 g h-1. Overall, the microdroplet/thin-film method offered several advantages including high efficiency, mild conditions, wide scope, and gram-scale ability, making it attractive for synthesizing 3-substituted indoles under the requirements of sustainable chemistry.

The gas|liquid interface eclipses the liquid|liquid interface for glucose oxidase rate acceleration in microdroplets

The curious chemistry observed in microdroplets has captivated chemists in recent years and has led to an investigation into their ability to drive seemingly impossible chemistries. One particularly interesting capability of these microdroplets is their ability to accelerate reactions by several orders of magnitude. While there have been many investigations into which reactions can be accelerated by confinement within microdroplets, no study has directly compared reaction acceleration at the liquid|liquid and gas|liquid interfaces. Here, we confine glucose oxidase, one of life's most important enzymes, to microdroplets and monitor the turnover rate of glucose by the electroactive cofactor, hexacyanoferrate (III). We use stochastic electrochemistry to monitor the collision of single femtoliter water droplets on an ultramicroelectrode. We also develop a measurement modality to robustly quantify reaction rates for femtoliter liquid aerosol droplets, where the majority of the interface is gas|liquid. We demonstrate that the gas|liquid interface accelerates enzyme turnover by over an order of magnitude over the liquid|liquid interface. This is the first apples-to-apples comparison of reaction acceleration at two distinct interfaces that indicates that the gas|liquid interface plays a central role in driving curious chemistry.

Regioselective Dimerization of Methylcyclopentadiene inside Cucurbit[7]uril.

The molecular confinement within rigid macrocyclic receptors can trigger catalytic activity and steer the selectivity of organic reactions. In this work, the dimerization of methylcyclopentadiene (MCPD) isomers in the presence of cucurbit[7]uril (CB7) was found to display, besides a large rate acceleration, a striking regioselectivity in aqueous solution at pH 3, different from the thermodynamic products predominating in the absence of the supramolecular catalyst. Among the different possible regioisomers and diastereomers, the endo-3,7-dimethyl-3a,4,7,7a-tetrahydro-1H-4,7-methanoindene adduct was selectively formed, which is otherwise found only as a minor product in the dimerization of neat MCPD or in commercial dimeric mixtures. This product originates from the reaction of the heteroternary complex of 1-MCPD and 2-MCPD within CB7, in which the methyl groups are positioned in an "anti-diaxial" arrangement and point towards the open portals of the macrocycle, resulting in a preferred packing of the reacting cyclopentadiene rings. The selectivity of the dimerization of MCPD in the absence and presence of CB7 is supported by quantum-chemical calculations. Insert abstract text here.

Enhancing optical absorbance and accelerating rotational speed in molecular motors through oriented external electric fields

Accelerating the rotational speed of light-driven molecular motors is among the foremost concerns in molecular machine research, as this speed directly influences the performance of a motor. Controlling the motor’s rotation is crucial for practical applications, and using an oriented external electric field (OEEF) represents a feasible method to achieve this objective. We have investigated the impact of an OEEF on the optical and kinetic properties of a novel π-donor/acceptor di-substituted molecular motor, R2,3-(NH2, CHO). We employed density functional theory (DFT) and time-dependent DFT methods to analyze the electronic excitation and thermal isomerization behavior. Our results demonstrate that the absorption wavelength, absorption efficiency of the motor, and rate constant of the thermal isomerization reaction can be adjusted by applying OEEFs, which are predictable based on the dipole moment and polarizability of the molecules under consideration. In particular, we observed a shift in the absorption wavelength toward longer ranges, an enhancement in light absorption intensity, and an acceleration in the rotation rate when applying a weak positive directional external electric field to the R2,3-(NH2, CHO) motor. In summary, this theoretical study highlights the potential of OEEFs for improving the performance of molecular motors.

Degradation effects of the rafts and dislocation network on creep property of single crystal superalloy at medium temperature

Generally, raft structure and interfacial dislocation networks enhance the creep resistance at elevated temperatures above 1000 °C and low stresses in Ni-based single crystal superalloys. However, the formation of raft structure and dislocation networks by raising the Mo content increased the creep rate at 900 °C and 392 MPa, accelerating the final failure. The formation of rafts was closely related to the creep rate acceleration, promoting dislocations piling up at the γ′/γ interface and the shearing events in the γ′ phase. Moreover, the dislocation networks formed at 900 °C and 392 MPa did not differentiate significantly with different Mo content, which could not enhance the creep resistance as expected. This work revealed the microstructural evolution at medium temperature and provided a new perspective for understanding the creep mechanisms and alloy design.

Understanding the Directed Evolution of a Natural-like Efficient Artificial Metalloenzyme.

The artificial metalloenzyme containing iridium in place of iron along with four directed evolution mutations C317G, T213G, L69V, and V254L in a natural cytochrome P450 presents an important milestone in merging the extraordinary efficiency of biocatalysts with the versatility of small molecule chemical catalysts in catalyzing a new-to-nature carbene insertion reaction. This is a show-stopper enzyme, as it exhibits a catalytic efficiency similar to that of natural enzymes. Despite this remarkable discovery, there is no mechanistic and structural understanding as to why it displays extraordinary efficiency after the incorporation of the four active site mutations by directed evolution methods, which so far has been intractable to any experimental methods. In this study, we have deciphered how directed evolution mutations gradually alter the protein conformational ensemble to populate a catalytically active conformation to boost a multistep catalysis in a natural-like artificial metalloenzyme using large-scale molecular dynamics simulations, rigorous quantum chemical (QM), and multiscale quantum chemical/molecular mechanics (QM/MM) calculations. It reveals how evolution precisely positions the cofactor-substrate in an unusual but effective orientation within a reshaped active site in the catalytically active conformation stabilized by C-H···π interactions from more ordered mutated L69V and V254L residues to achieve preferential transition state stabilization compared to the ground state. This work essentially tracks down in atomistic detail the shift in the conformational ensemble of the highly active conformation from the less efficient single mutant to the most efficient quadruple mutant and offers valuable insights for designing better enzymes. The active conformation correctly reproduces the experimental barrier height and also accounts for the catalytic effect, which is in good agreement with experimental observations. Moreover, this conformation features an unusual bonding interaction in a metal-carbene species that preferentially stabilizes the rate-determining formation of an iridium porphyrin carbene intermediate to render the observed high catalytic rate acceleration. Our study provides crucial insights into the underlying rationale for directed evolution, reports the major catalytic role of nonelectrostatic interactions in enzyme catalysis different from the electrostatic model, and suggests a crucial principle toward designing enzymes with natural efficiency.

Atmospheric Corrosion of Aluminum and Aluminum/Gold Thin Films

Aluminum and its alloys are extensively utilized in various applications due to their high thermal and electrical conductivity and inherent resistance to corrosion, primarily due to the formation of a protective oxide layer. However, the strength, durability and electrical properties of many aluminum-based materials and aluminum/gold contacts tend to diminish in humid environments. Therefore, a thorough understanding of the mechanistic aspects of atmospheric corrosion reactions over time in pure Al and galvanic Al/Au couples is crucial for predicting degradation and optimizing performance. Presently, much of our knowledge regarding atmospheric aluminum corrosion is derived from empirical correlations based on extensive corrosion data, typically involving a simplistic relationship between corrosion rates and environmental factors. However, the mechanistic understanding of corrosion processes, particularly during in the presence of electrolytes like sodium chloride found in the environment is not fully elucidated.Here we propose a new surface approach to obtain mechanistic insights into atmospheric corrosion of Al and Al/Au thin films in the presence of NaCl. The corrosion rate is investigated through a combination of experimental and theoretical approaches, correlating corrosion kinetics with electrolyte chemistry, mass changes, and corrosion byproducts. Quartz crystal microbalance with dissipation (QCM-D) electrodes coated with aluminum and aluminum/gold contacts and sodium chloride serve as the experimental platform. The structure, composition, and surface morphology of the samples are analyzed using various techniques including grazing-incidence X-ray diffraction, FTIR spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy, and electron energy loss spectroscopy. Operando data with nanogram resolution provided by the QCM-D technique allows real-time monitoring of corrosion product formation, facilitating the derivation of rate constants for corrosion surface reactions. It is observed that the reaction rate in dry air is negligible, but a significant acceleration occurs at relative air humidity levels of 50% and above. Additionally, this study delves into the impact of sodium chloride on the corrosion rate and reaction products, the influence of surface termination on aluminum oxide/hydroxide formation, and the temperature-dependent acceleration of electrochemical corrosion rates. Finally, by integrating theoretical insights with experimental findings, preliminary understanding of the rate-limiting steps has been achieved, paving the way for the development of validated computational models to simulate early-stage atmospheric corrosion processes.

Evolutionary analysis of Hemagglutinin and neuraminidase gene variation in H1N1 swine influenza virus from vaccine intervention in China

Influenza poses a significant threat to the global economy and health. Inactivated virus vaccines were introduced in China for prevention in 2018. In this study, three pairs of hemagglutinin (HA) and neuraminidase (NA) gene sequences were obtained from three Swine influenza virus (IAV-S) inactivated vaccine strains that were marketed in China in 2018. Phylogenetic analysis was carried out with HA and NA gene sequences to investigate the relationship between vaccine use and virus genetic drift. The findings showed that the evolutionary rate of HA remained relatively stable from 2012 to 2017, with an average genetic distance of approximately 0.020731195. However, following the introduction of the swine influenza vaccine, there was a notable acceleration in the evolutionary rate of HA, accompanied by a significant increase in the genetic distance. In 2018, the value was 0.111750269, while in 2019 it was 0.176389393. In contrast, the evolution of NA was relatively smooth, with an average genetic distance of approximately 0.030386708. Finally, we demonstrated that commercial vaccines are weak neutralizers of wild strains through immunization experiments in animals. Thus, we have reason to believe that mutations in the virus favor virus evasion of vaccine immunity. Our findings suggest that vaccine use may significantly impact the evolution of the influenza virus by potentially stimulating mutations. The selection pressure of vaccine antibodies played a role in regulating the variation of IAV-S-H1N1.

Delayed response of the coastal sedimentary record to the southward shift of the Huanghe (Yellow River) course during AD1128–1855

The sediment source-to-sink process is an important topic in marine sedimentology. However, how sedimentary signals evolve along source-to-sink path remains less clear. This study focuses on the southward shift of the Huanghe River course between AD 1128 and 1855, and the manifestation and variation of sedimentary signals in a natural diffusion system were investigated through sedimentological analysis of three spatially adjacent regions, the abandoned Huanghe Delta, the central coast of Jiangsu, and the Changjiang Delta. Laboratory analyses including Optically Stimulated Luminescence (OSL), geochemical element analysis, and grain size analysis, were conducted. The results show that sedimentary signals manifest in various forms, primarily manifested in two ways: grain size refinement and sedimentation rate acceleration. The fining of grain size is most pronounced in the abandoned Huanghe delta, followed by the central coast of Jiangsu, and is least pronounced in the Changjiang subaqueous delta. The response of the coastal system to the event was delayed by approximately 0–100, 100–300, and 300–500 years for the abandoned Huanghe Delta, the central coast of Jiangsu, and the Changjiang River Delta, respectively. These findings indicate that sediment transport processes exhibit sedimentary signal attenuation and response lag. This study not only highlights the variation along the source-sink path of coastal sedimentary signals but also illuminates the sedimentary record of drastic changes in sediment flux, which will help study the source-to-sink process given the variable changes in sedimentary fluxes.