Time-dependent Profiles Research Articles

Time-dependent longitudinal deformation profiles for circular tunnels in squeezing ground conditions: a Seri Nala case study

Time-dependent longitudinal deformation profiles for circular tunnels in squeezing ground conditions: a Seri Nala case study

Rationale and Logistics of Continuous Infusion Cephalosporin Antibiotics.

Cephalosporins have traditionally been administered as an intermittent infusion. With the knowledge that cephalosporins demonstrate a time-dependent pharmacodynamic profile, administration via continuous infusion may provide more effective antibiotic exposure for successful therapy. Proposed benefits of administration via continuous infusion include less IV manipulation, decreased potential for antibiotic resistance, and potential cost savings. The objective of this review was to provide a detailed assessment of available evidence for the use of continuous infusion cephalosporins and practical dosing and administration recommendations. Studies were gathered and assessed for inclusion via a literature search of PubMed and Ovid MEDLINE using mesh terms ["continuous infusion" and "cephalosporin"], "intermittent infusion", ["intermittent versus continuous" and "cephalosporin"], "continuous infusion cephalosporin", as well as specific drug names. References from included studies were also evaluated for inclusion. Data which compared the two administration methods (continuous infusion vs. intermittent infusion) were evaluated. Thirty-five studies were analyzed among several cephalosporins with variable delivery. Dosing regimens utilized in the selected studies were assessed with known compatibility and stability data and further summarized.

Stress-Driven Diffusion of Lithium into Anode Copper Current Collectors during Plating and Stripping

Stresses in lithium metal anodes determine their stability during inevitable volume changes experienced upon cycling. Lithium deformation during cycling in liquid cells can initiate surface morphological instabilities which lead to capacity loss, e. g. whiskers and moss (1-3). Evidence suggests that whiskers grow by solid-state diffusion to the whisker base (3,4), and that whiskers relieve compressive stress in the metal generated by electrodeposition (5,6). While quantitative characterization of these processes is challenging, diffusion accompanying morphology instabilities can be detected when lithium is deposited directly on copper current collectors (7-9). Lv et al. reported operando neutron depth profiling (NDP) measurements of Li diffusion into Cu during plating-stripping cycles (9). NDP demonstrated reversible intercalation of Li in the current collector, and diffusion toward higher concentration during stripping, thus contrary to Fick's Law.A model is presented for lithium diffusion in a copper current collector during cycling in a liquid cell. Based on our recent analysis of stress measurements during cycling (10), diffusion of plated atoms into the deposit induces lateral expansion of the copper-deposit interface, which is accommodated by stress-driven diffusion of lithium into grain boundaries in the copper foil. During stripping atoms diffuse of the deposit, leading to contraction along the copper interface. Following established practices, stress due to grain boundary diffusion is modeled by tracking evolution of wedges of additional material adjacent to the boundaries (11-13).The calculations demonstrated growth and contraction of wedges during plating and stripping respectively, accounting for the observed reversible lithium intercalation. When the effective diffusivity is larger than 10-13 m2/s, model calculations successfully captured the linear time-dependent concentration profiles measured by NDP. Creep accompanying grain-boundary diffusion creep resulted in low levels of stress and deformation in the copper foil. The fit diffusivity value was comparable to Li diffusivities previously reported in current collectors and alloy anodes during cycling, but much larger than diffusivities from ex situ experiments. The agreement demonstrated between the model and NDP measurements supports the hypothesis that plating and stripping reactions induce diffusion within the lithium deposit. Stress due to diffusion may play an important role in the morphological instability of the lithium-electrolyte interface during cycling.REFERENCES P. Bai, J. Li, F. R. Brushett, M. Z. Bazant, Energy Environ. Sci. 9, 3221 (2016).L Frenck, G. K. Sethi, J. A. Maslyn, N. P. Balsara, Front. Energy Res. 7, 115 (2016)A. Kushima, et al., Nano Energy 32, 271 (2017).J. A. Becherer, D. Kramer, and R. Mönig J. Mater. Chem. A., 10, 5530 (2022).X. Wang et al., Nat. Energy 3, 227 (2018).W. J. Boettinger et al., Acta Mater. 53, 5033 (2005).J. Suzuki, K. Sekine, T. Takamura, Electrochemistry 71, 1120 (2003)D. Rehnlund et al., Energy Environ. Sci. 10, 1350 (2017).S. Lv et al., Nat. Commun. 9,2152 (2018)K. R. Hebert, J. Electrochem. Soc. 170, 110537 (2023).H. Gao et al., Acta Mater. 47, 2865 (1999).P. Guduru, E. Chason, and L. B. Freund, J. Mech. Phys. Solids 51, 2127 (2003).L. Klinger and E. Rabkin, Acta Mater. 59, 1389 (2011).

Characterising the transcriptomic response of bovine peripheral blood mononuclear cells to a mycobacterial cell wall fraction

BackgroundInnate immune stimulants, including mycobacterium cell wall fractions (MCWF), offer an alternative control option to prevent and treat disease in livestock, by appropriately augmenting the innate immune response. However, the functional response to mycobacterium cell wall fractions in cattle is not well defined. In this study we report the transcriptomic response of bovine peripheral blood mononuclear cells to MCWF in the product Amplimune®. MethodsAmplimune-induced transcriptomic changes in bovine peripheral blood mononuclear cells were determined following an initial pilot study and a later time course experiment. These cells were cultured in vitro for 24 h. In the pilot experiment, cells were stimulated with 0, 2, 5, 12.5 or 31.25 µg/mL Amplimune. In the time course experiment, cells were stimulated with 0 or 31.25 µg/mL Amplimune. In both experiments the total RNA was extracted at 0 h, 6 h and 24 h following stimulation. Ribosomal RNA depleted samples were sequenced, and data analysed to determine differential gene expression profiles. Differential gene expression was further analysed to determine enriched biological processes and pathways and a co-expression network. Results and conclusionAmplimune induced dose- and time-dependent gene expression profile changes in bovine peripheral blood mononuclear cells, which were enriched into GO-BP regulation of signalling receptor activity, response to cytokine and inflammatory response. Enriched pathways from KEGG analysis were cytokine-cytokine receptor interaction, IL17 signalling and TNF signalling pathways. Selected genes involved in these processes and pathways included IFNG, IL17A, TNF, IL22 and IL23A. PDE1B, CSF2 and IL36G were identified as the most connected genes in a co-expression network, while the connection between SAA2 and SIGLEC5 was the most important for flow of information within the network. Genes encoding for pro-inflammatory cytokines TNF, IL1B, IL6, IL2, and IL12B, and chemokines CCL3, CCL4 and CCL20 were also upregulated at 6 and 24 h post stimulation, as was the β-defensin gene TAP. These results assist in understanding how mycobacterial cell wall fractions alter immune function and may contribute to our understanding of the immune stimulant response attributed to Amplimune.

Simulation of homogenization behavior of compacted bentonite containing technological voids using modified penalty-based contact model

Low-density zones generated during the bentonite blocks/voids homogenization process in the repository may serve as potentially preferential paths for radionuclide leakage. More importantly, void closure during homogenization process involves complex contact problems, where the stiffness at the contact interface typically undergoes significant fluctuations. In this work, with contact interface stiffness addressed through a step function approach, a modified penal.ty-based contact model was proposed to simulate the contact behavior involved at the gap closure stage of the bentonite/gap assemblage homogenization process. Then, unsaturated infiltration swelling tests on bentonite block (1.7 Mg/m3)/gap (width: 2 mm) assemblages were performed, and the variation of dry density at different hydrated times (0, 24, 72, 168, and 720 h) in specific areas were measured. Based on the results, time-dependent swelling pressure profiles of the assemblage were acquired, while the homogenization process was evaluated. Results reveal that after approximately 40 h of hydration, the gap is completely closed, and the radial stress condition of the compacted bentonite transits progressively from the initial free swelling into a constant volume expansion state. The swelling pressure correspondingly develops quickly to a peak value at 1.8 MPa once the hydration starts, then decreases to a valley value of 1.4 MPa at the complete gap closure, and subsequently begins to increase to the final stable value of 1.8 MPa. Further examination reveals that as hydration advances, dry density of the assemblage converges to the expected final dry density with a maximum residual inhomogeneity of about 2 %. Finally, validations demonstrate that the proposed model can accurately reproduce deformations of the assemblage during the free swelling stage, and the swelling pressure profiles. A comparative analysis was made with the previous approach of identifying gaps as highly deformable materials, revealing that the proposed model overcomes the traditional limitations associated with the separation or penetration behavior occurring between the compacted bentonite and contact boundaries during the gap closure.

Numerical Investigation of Flow Inside a Channel with Elastic Vortex Generator and Elastic Wall for Heat Transfer Enhancement

In the present investigation, a detailed numerical investigation of the flow and heat transfer characteristics of a channel with an elastic fin (vortex generator) and an elastic wall has been carried out using finite element method. The Fluid-Structure Interaction (FSI) model is used to capture the interaction between the fluid and the solid structure. A sinusoidal time dependent velocity profile has been imposed at the inlet of the channel and the right half of the upper wall of the channel is heated and exposed to constant temperature boundary condition. Due to the sinusoidal velocity profile at the inlet, the elastic fin oscillates periodically and act as a vortex generator, which causes more turbulence in the flow. The obtained results showed that the Nusselt number over the heated wall is affected by the position of the flexible fin, height of flexible fin and elasticity modulus of elastic fin. Moreover, due to the elasticity of the elastic wall and sinusoidal behavior of the inlet velocity, the elastic wall oscillates periodically upward and downward. The Nusselt number values over the heated wall are increased with decrease of the elastic modulus value of the elastic wall. However, the decrease in elastic modulus value of the elastic wall contributes to an increase in the pressure drop inside the channel. It should be added that the interplay between the fluid motion and the deformable structures leads to enhanced turbulence, as the flexible fin and elastic wall introduce additional disturbances and fluctuations into the flow regime. Consequently, this heightened turbulence level has profound implications for heat transfer processes within the system.

Gyrokinetic flux-driven simulations in mixed TEM/ITG regime using a delta-f PIC scheme with evolving background

In the context of global gyrokinetic simulations of turbulence using a particle-in-cell framework, verifying the delta-f assumption with a fixed background distribution becomes challenging when determining quasi-steady state profiles corresponding to given sources over long time scales, where plasma profiles can evolve significantly. The advantage of low relative sampling noise afforded by the delta-f scheme is shown to be retained by considering the background as a time-evolving Maxwellian with time-dependent density and temperature profiles. Implementation of this adaptive scheme to simulate electrostatic collisionless flux-driven turbulence in tokamak plasmas show small and nonincreasing sampling noise levels, which would otherwise increase indefinitely with a stationary background scheme. The adaptive scheme furthermore allows one to reach numerically converged results of quasi-steady state with much lower marker numbers.

A role for root carbonic anhydrase βCA4 in the bicarbonate tolerance of Arabidopsis thaliana.

Carbonic anhydrases (CAs) are the main enzymes handling bicarbonate in the different cell compartments. This study analyses the expression of CAs in roots of Arabidopsis thaliana demes differing in tolerance to bicarbonate: the tolerant A1(C+) deme and the sensitive deme, T6(C-). Exposure to 10 mM NaCl caused a transient depolarization of the root cell membranes, and in contrast, the supply of 10 mM NaHCO3 caused hyperpolarization. This hyperpolarization was much stronger in A1(C+) than in T6(C-). Acetazolamide (AZ), a specific inhibitor of CAs, abolished the hyperpolarizing effect in A1(C+), indicating the implication of CAs in this fast membrane response. The time-dependent (3 to 72 h) expression profiles of 14 CAs in roots of A1(C+) and T6(C-) exposed to either control (0 mM NaHCO3, pH 5.9), or bicarbonate (10 mM NaHCO3,pH 8.3) conditions revealed a bicarbonate specific upregulation of BCA4.1 (from 3 to 12 h) in A1(C+). Contrastingly, in T6(C-) BCA4.1 was downregulated by NaHCO3. Exclusively in A1(C+), the enhanced expression of BCA4.1 under bicarbonate was parallelled by an increase of PIP1,3, SLAH1, SLAH3, AHA2, and FRO2 gene expression levels. Under HCO3 - exposure, a bca4 knockout mutant had a lower number of lateral roots, lower root diameters, and higher root lipid peroxidation than the WT. These results indicate that bicarbonate-induced root membrane hyperpolarization is the fast (minutes) initial signalling event in the tolerance response. This is followed by the specific upregulation of BCA4.1 and genes involved in H2O and CO2 transport, apoplast acidification, and iron acquisition.

Capturing the mechanosensitivity of cell proliferation in models of epithelium

Despite the primary role of cell proliferation in tissue development and homeostatic maintenance, the interplay between cell density, cell mechanoresponse, and cell growth and division is not yet understood. In this article, we address this issue by reporting on an experimental investigation of cell proliferation on all time- and length-scales of the development of a model tissue, grown on collagen-coated glass or deformable substrates. Through extensive data analysis, we demonstrate the relation between mechanoresponse and probability for cell division, as a function of the local cell density. Motivated by these results, we construct a minimal model of cell division in tissue environment that can recover the data. By parameterizing the growth and the dividing phases of the cell cycle, and introducing such a proliferation model in dissipative particle dynamics simulations, we recover the mechanoresponsive, time-dependent density profiles in 2D tissues growing to macroscopic scales. The importance of separating the cell population into growing and dividing cells, each characterized by a particular time scale, is further emphasized by calculations of density profiles based on adapted Fisher-Kolmogorov equations. Together, these results show that the mechanoresponse on the level of a constitutive cell and its proliferation results in a matrix-sensitive active pressure. The latter evokes massive cooperative displacement of cells in the invading tissue and is a key factor for developing large-scale structures in the steady state.

Tailoring Fumaric Acid Delivery: The Role of Surfactant-Enhanced Solid Lipid Microparticles via Spray-Congealing.

Fumaric acid, a naturally occurring preservative with antimicrobial properties, has been widely used in the baking industry. However, its direct addition interferes with yeast activity and negatively impacts the gluten structure. This study investigates the potential of spray-congealing as a method for encapsulating fumaric acid within solid lipid microparticles. The selection of lipid carriers and surfactants is critical, so hydrogenated palm stearin, hydrogenated rapeseed oil, and Compritol ATO 888 (glyceryl behenate) were chosen as lipid carriers, and propylene glycol monostearate and glyceryl monolaurate were utilised as surfactants with varying concentrations. Rheological properties, encapsulation efficiency, particle size, moisture content, and thermal behaviour were assessed, along with the release profiles under different temperature conditions simulating the baking process. The findings indicate that the addition of surfactants significantly impacts the viscosity and stability of the molten mixtures, which in turn affects the spray-congealing process and the release of fumaric acid. The temperature-dependent and time-dependent release profiles demonstrate the potential for customising release kinetics to suit specific applications, such as the baking industry. This study may contribute to the development of a controlled-release system that synchronises with the baking process, thereby optimising fumaric acid's functionality while preserving the quality of baked goods.

Involvement of extracellular vesicle microRNA clusters in developing healthy and Rett syndrome brain organoids

Rett syndrome (RTT) is a neurodevelopmental disorder caused by de novo mutations in the MECP2 gene. Although miRNAs in extracellular vesicles (EVs) have been suggested to play an essential role in several neurological conditions, no prior study has utilized brain organoids to profile EV-derived miRNAs during normal and RTT-affected neuronal development. Here we report the spatiotemporal expression pattern of EV-derived miRNAs in region-specific forebrain organoids generated from female hiPSCs with a MeCP2:R255X mutation and the corresponding isogenic control. EV miRNA and protein expression profiles were characterized at day 0, day 13, day 40, and day 75. Several members of the hsa-miR-302/367 cluster were identified as having a time-dependent expression profile with RTT-specific alterations at the latest developmental stage. Moreover, the miRNA species of the chromosome 14 miRNA cluster (C14MC) exhibited strong upregulation in RTT forebrain organoids irrespective of their spatiotemporal location. Together, our results suggest essential roles of the C14MC and hsa-miR-302/367 clusters in EVs during normal and RTT-associated neurodevelopment, displaying promising prospects as biomarkers for monitoring RTT progression.Graphical

Heavy metals altered the xenobiotic metabolism of rats by targeting the GST enzyme: An in vitro and in silico study

Among all the heavy metals, Pb, Cd, and As are the most harmful pollutants in the environment. They reach into the organisms via various levels of food chains i.e. air and water. Glutathione-s-transferase (GST, E.C. 2.5.1.18), a key enzyme of xenobiotics metabolism, plays an important role in the removal of several toxicants. The present study aimed to evaluate any inhibitory action of these heavy metals on the GST enzyme isolated from the hepatic tissues of rats. A 10 % (w/v) homogenate of rat liver was prepared in cold and centrifuged at 4 °C at 9000xg for 30 min. The supernatant was collected and kept frozen at −20 °C or used fresh for carrying out different experiments. The activity of GST was monitored spectrophotometrically at 340 nm using 220 μg of soluble protein with varying equal substrate concentrations (0.125–2 mM) in phosphate buffer (50 mM, pH 6.5). To assess the impact of heavy metals on the enzyme activity, different concentrations of Cd (0–0.6 mM) and Pb (0–2 mM) were added to the reaction mixture followed by monitoring the residual activity. The optimum temperature and pH of rat liver GST were found to be 37 °C and 6.5, respectively. The Km value for GST was 0.69 mM and the Vmax was found to be 78.67 U/mg. The Cd and Pb significantly altered the kinetic behaviour of the enzyme. The Vmax and Kcat/Km parameters of GST were recorded to be decreased after interaction with Cd and Pb individually and showed a mixed type of inhibition pattern suggesting that these inhibitors may have a greater binding affinity either for the free enzyme or the substrate-enzyme complex. These metals showed a time-dependent enzyme inhibition profile. Cd was found to be the most potent inhibitor when compared to other treated metals; the order of inhibitory effect of metal ions was Cd>Pb>As. The in silico ion docking analysis for determining the probable interactions of Cd and Pb with fragmented GST validated that Cd exhibited higher inhibition potential for the enzyme as compared to Pb. The results of the present study indicated that exposure of both the Cd and Pb may cause significant inhibition of hepatic GST; the former with higher inhibitory potential than the later. However, As proved to be least effective against the enzyme under the aforesaid experimental conditions.

Electrochemical-mechanical coupled lithium growth in fiber-structured electrodes

Lithium plating (stripping) on the electrode surface and embedding inside the electrode occur simultaneously in lithium-ion batteries during fast (dis)charging, which involves both deposition and diffusion mechanisms. The paper presents a developed finite-element procedure that accommodates these two mechanisms, facilitating the modeling of the (dis)charging process in electrodes. The framework, which integrates interface electrochemical reaction kinetics, electrochemical-mechanical coupling, comprehensive constitutive models for silicon/graphite/lithium, and a surface growth re-meshing algorithm, is capable of real-time simulation of the surface deposition and coupled diffusion-deformation processes on the electrode substrate. We examined the effects of charging rate, diffusion rate and volumetric expansion on the stress of the plated lithium layer in a fiber-structured electrode. By accounting for creep in lithium metal and subsequent stress relaxation, we obtained time-dependent stress profiles in the plated lithium layer. As an application, we quantified electroplating stresses in both fiber-structured graphite and silicon electrodes. Taking the silicon electrode as a model case, we demonstrate that hollow fiber structural electrodes can also alleviate the stress in the surface lithium-plating layer. The numerical framework may be further applied to explorations for the optimization of electrode structures in advanced high performance lithium-ion batteries.

The role of time-varying external factors in the intensification of tropical cyclones

Abstract. The role of time-varying external parameters in tropical cyclone (TC) dynamics is explored through a low-order conceptual box model. Specifically, we look at stable-to-stable state transitions which may be linked to tropical cyclone intensification, dissipation, or eyewall replacement cycles (ERCs). To this end, we identify two parameters of interest: the exponent of radial decline and sea-surface temperature. We examine how variations in these parameters affect the stable states of the model and consider the behaviour of the system under different time-dependent forcing profiles for the parameters. By externally forcing the exponent of radial decline and sea-surface temperature, we show the existence of rate-dependent behaviour in the model. These findings are brought together in a case study of Hurricane Irma (2017). The results highlight the role of the radial vorticity gradient in behaviour such as rate-induced tipping and overshoot recovery. They also show that a simple model can be used to explore relatively complex tropical cyclone dynamics.

Temperature evolution of laser-ignited micrometric iron particles: A comprehensive experimental data set and numerical assessment of laser heating impact

This study examines the effects of laser heating on the ignition and critical combustion characteristics, such as temperature and burn time, of individual iron particles. It provides time-dependent temperature profiles of laser-ignited particles across a broad spectrum of particle size distributions and oxygen concentrations obtained from experiments, which are a useful database for further development and validation of iron particle combustion models. The herein reported datasets significantly complement those existing in the literature. In the current study, the raw data are thoroughly re-evaluated using refined approaches. For the experimental canonical configuration of single iron particle combustion, an ignition system based on laser heating provides several advantages in overcoming temperature field uncertainties and facilitating controlled environments for optical diagnostics. Despite the inherent uncertainties in laser heating, associated with non-uniform intensity profiles and particle size variations, this study addresses the critical question of how these uncertainties affect in situ measurements of particle temperature and time to reach peak temperature. This study, conducted using a numerical model, reveals a dependence of the particle temperature after laser heating on particle size. However, this dependence does not significantly impact the key parameters of iron-particle combustion, such as the maximum temperature and burn time of the laser-ignited iron particle. The study also presents a comparison between the simulated particle temperature histories and those derived from two-color pyrometry measurements for a wide range of particle size distributions and oxygen concentrations. Notably, by implementing a laser-heating sub-model into an iron particle combustion model, assuming external-diffusion-limited oxidation only up to stoichiometric FeO, the temperature evolution up to the maximum temperature is reasonably captured for a wide range of particle sizes (20–53μm) and oxygen volumetric fractions (14–21vol% O2 mixed with N2). However, with increasing oxygen concentration, the external-diffusion limited model significantly overestimates the heating rate and subsequently the maximum particle temperature.

Scalar field dark matter: impact of supernova-driven blowouts on the soliton structure of low-mass dark matter haloes

ABSTRACT We present the first study on the gravitational impact of supernova feedback in an isolated soliton and a spherically symmetric dwarf scalar field dark matter (SFDM) halo of virial mass $1\times 10^{10}\,\mathrm{M_\odot }$. We use a boson mass $m=10^{-22}\,\mathrm{eV\,c^{-2}}$ and a soliton core $r_\mathrm{ c} \approx 0.7$ kpc, comparable to typical half-light radii of Local Group dwarf galaxies. We simulate the rapid gas removal from the centre of the soliton by a concentric external time-dependent Hernquist potential. We explore two scenarios of feedback blowouts: (i) a massive single burst and (ii) multiple consecutive blowouts injecting the same total energy to the system, including various magnitudes for the blowouts in both scenarios. In all cases, we find one single blowout has a stronger effect on reducing the soliton central density. Feedback leads to central soliton densities that oscillate quasi-periodically for an isolated soliton and stochastically for an SFDM halo. The range in the density amplitude depends on the strength of the blowout; however, we observe typical variations of a factor of $\geqslant$2. One important consequence of the stochastic fluctuating densities is that, if we had no prior knowledge of the system evolution, we can only know the configuration profile at a specific time within some accuracy. By fitting soliton profiles at different times to our simulated structures, we found the (1$\sigma$) scatter of their time-dependent density profiles. For configurations within the 1$\sigma$ range, we find the inferred boson mass is typically less than 20 per cent different from the real value used in our simulations. Finally, we compare the observed dynamical masses of field dwarf galaxies in our Local Group with the implied range of viable solitons from our simulations and find good agreement.

Transport of plant growth promoting bacteria (Azospirillum brasilense) in sand under transient water flow: effect of inoculation regime

HighlightsTime dependent deposition of two Azospirillum brasilense strains in sand quantified.Three inclusions regimes examined: surface, subsurface and premixed.For surface and subsurface the bacteria accumulated near the point source and remained stagnant in the premixed.The attachment/detachment numerical model found adequate to describe the time dependent deposition profiles of the bacteria.

Tissue- and time-dependent metabolite profiles during early grain development under normal and high night-time temperature conditions

BackgroundWheat grain development in the first few days after pollination determines the number of endosperm cells that influence grain yield potential and is susceptible to various environmental conditions, including high night temperatures (HNTs). Flag leaves and seed-associated bracts (glumes, awn, palea, and lemma) provide nutrients to the developing seed. However, the specific metabolic roles of these tissues are uncertain, especially their dynamics at different developmental stages and the time in a day. Tissue- and time-dependent metabolite profiling may hint at the metabolic roles of tissues and the mechanisms of how HNTs affect daytime metabolic status in early grain development.ResultsThe metabolite profiles of flag leaf, bract, seed (embryo and endosperm), and entire spike were analyzed at 12:00 (day) and 23:00 (night) on 2, 4, and 6 days after fertilization under control and HNT conditions. The metabolite levels in flag leaves and bracts showed day/night oscillations, while their behaviors were distinct between the tissues. Some metabolites, such as sucrose, cellobiose, and succinic acid, showed contrasting oscillations in the two photosynthetic tissues. In contrast, seed metabolite levels differed due to the days after fertilization rather than the time in a day. The seed metabolite profile altered earlier in the HNT than in the control condition, likely associated with accelerated grain development caused by HNT. HNT also disrupted the day/night oscillation of sugar accumulation in flag leaves and bracts.ConclusionsThese results highlight distinct metabolic roles of flag leaves and bracts during wheat early seed development. The seed metabolite levels are related to the developmental stages. The early metabolic events in the seeds and the disruption of the day/night metabolic cycle in photosynthetic tissues may partly explain the adverse effects of HNT on grain yield.

Development of an Elementary Reaction-Based Kinetic Model to Predict the Aqueous-Phase Fate of Organic Compounds Induced by Reactive Free Radicals.

ConspectusAqueous-phase free radicals such as reactive oxygen, halogen, and nitrogen species play important roles in the fate of organic compounds in the aqueous-phase advanced water treatment processes and natural aquatic environments under sunlight irradiation. Predicting the fate of organic compounds in aqueous-phase advanced water treatment processes and natural aquatic environments necessitates understanding the kinetics and reaction mechanisms of initial reactions of free radicals with structurally diverse organic compounds and other reactions. Researchers developed conventional predictive models based on experimentally measured transformation products and determined reaction rate constants by fitting with the time-dependent concentration profiles of species due to difficulties in their measurements of unstable intermediates. However, the empirical treatment of lumped reaction mechanisms had a model prediction limitation with respect to the specific parent compound's fate. We use ab initio and density functional theory quantum chemical computations, numerical solutions of ordinary differential equations, and validation of the outcomes of the model with experiments. Sensitivity analysis of reaction rate constants and concentration profiles enables us to identify an important elementary reaction in formating the transformation product. Such predictive elementary reaction-based kinetics models can be used to screen organic compounds in water and predict their potentially toxic transformation products for a specific experimental investigation.Over the past decade, we determined linear free energy relationships (LFERs) that bridge the kinetic and thermochemical properties of reactive oxygen species such as hydroxyl radicals (HO•), peroxyl radicals (ROO•), and singlet oxygen (1O2); reactive halogen species such as chlorine radicals (Cl•) and bromine radicals (Br•); reactive nitrogen species (NO2•); and carbonate radicals (CO3•-). We used literature-reported experimental rate constants as kinetic information. We considered the theoretically calculated aqueous-phase free energy of activation or reaction to be a kinetic or a thermochemical property, and obtained via validated ab initio or density functional theory-based quantum chemical computations using explicit and implicit solvation models. We determined rate-determining reaction mechanisms involved in reactions by observing robust LFERs. The general accuracy of LFERs to predict aqueous-phase rate constants was within a difference of a factor of 2-5 from experimental values.We developed elementary reaction-based kinetic models and predicted the fate of acetone induced by HO• in an advanced water treatment process and methionine by photochemically produced reactive intermediates in sunlit fresh waters. We provided mechanistic insight into peroxyl radical reaction mechanisms and critical roles in the degradation of acetone and the formation of transformation products. We highlighted different roles of triplet excited states of two surrogate CDOMs, 1O2, and HO•, in methionine degradation. Predicted transformation products were compared to those obtained via benchtop experiments to validate our elementary reaction-based kinetic models. Predicting the reactivities of reactive halogen and nitrogen species implicates our understanding of the formation of potentially toxic halogen- and nitrogen-containing transformation products during water treatment processes and in natural aquatic environments.

Time-dependent probabilistic tsunami risk assessment: application to Tofino, British Columbia, Canada, subjected to Cascadia subduction earthquakes

A new time-dependent probabilistic tsunami risk model is developed to facilitate the long-term risk management strategies for coastal communities. The model incorporates the time-dependency of earthquake occurrence and considers numerous heterogeneous slip distributions via a stochastic source modeling approach. Tidal level effects are examined by considering different baseline sea levels. The model is applied to Tofino, British Columbia, Canada within the Cascadia subduction zone. High-resolution topography and high-quality exposure data are utilized to accurately evaluate tsunami damage and economic loss to buildings. The results are tsunami loss curves accounting for different elapsed times since the last major event. The evolutionary aspects of Tofino’s time-dependent tsunami risk profiles show that the current tsunami risk is lower than the tsunami risk based on the conventional time-independent Poisson occurrence model. In contrast, the future tsunami risk in 2100 will exceed the time-independent tsunami risk estimate.