Risk assessment of Arsenic in surface water of China water systems based on a time-dependent species sensitivity distribution (SSD) method.

Arsenic (As) is a naturally occurring metalloid element widespread in the environment. Assessing the ecological risk of As in surface water, especially the acute risk caused by emergent pollution incidents, is of great significance. However, acute toxicity data including median lethal concentration (LC50) and median effective concentration (EC50) of As derived by toxicology experiment may vary according to the exposure time, which is referred as time dependence effect. Time dependence not only affects toxicity data but also influences the characterization of acute risk in the ecosystem. However, previous research on the time dependence effect of As, especially the quantitative influence on the risk assessment is still limited. In this research, acute toxicity data of As(III) and As(V) was collected. Time dependence of toxicology data of inorganic As was studied. Time-dependent species sensitivity distributions of freshwater species were established. The hazardous concentration for 5% of species (HC5) values in different exposure time were further derived. Finally, the dynamic ecological risk of As in major Chinese water basins was evaluated. The results suggested that the toxicity data of inorganic As had a significant linear relationship (p < 0.01) with time. The HC5 values of As (III) and As (V) at an exposure time of four days were reduced by 15.5% and 77.5%, respectively, as compared to the HC5 value of one day. According to the ecological risk characterized by the probability density overlapping area method, the ecological risk of As(III) and As(V) increases with the exposure duration. The Yangtze River had the highest risk, with risk values ranging from 19.9% to 22.6%. According to the results, the time dependence of toxicity data should be fully considered in the formulation of water quality criteria or ecological risk assessment so as to provide better protection for the water ecosystem security.

Oligotrophic state reduces the time dependence of the observed survival fraction for heavy ion beam-irradiated Saccharomyces cerevisiae and provides new insights into DNA repair.

Heavy ion beam (HIB) irradiation is widely utilized in studies of cosmic rays-induced cellular effects and microbial breeding. Establishing an accurate dose-survival relationship is crucial for selecting the optimal irradiation dose. Typically, after irradiating logarithmic-phase cell suspensions with HIB, the survival fraction (SF) is determined by the ratio of clonal-forming units in irradiated versus control groups. However, our findings indicated that SF measurements were time sensitive. For the Saccharomyces cerevisiae model, the observed SF initially declined and subsequently increased in a eutrophic state; conversely, in an oligotrophic state, it remained relatively stable within 120 minutes. This time effect of SF observations in the eutrophic state can be ascribed to HIB-exposed cells experiencing cell cycle arrest, whereas the control proliferated rapidly, resulting in an over-time disproportionate change in viable cell count. Therefore, an alternative involves irradiating oligotrophic cells, determining SF thereafter, and transferring cells to the eutrophic state to facilitate DNA repair-mutation. Transcriptomic comparisons under these two trophic states yield valuable insights into the DNA damage response. Although DNA repair was postponed in an oligotrophic state, cells proactively mobilized specific repair pathways to advance this process. Effective nutritional supplementation should occur within 120 minutes, beyond this window, a decline in SF indicates an irreversible loss of repair capability. Upon transition to the eutrophic state, S. cerevisiae swiftly adapted and completed the repair. This study helps to minimize time-dependent variability in SF observations and to ensure effective damage repair and mutation in microbial breeding using HIB or other mutagens. It also promotes the understanding of microbial responses to complex environments.IMPORTANCEMutation breeding is a vital means of developing excellent microbial resources. Consequently, understanding the mechanisms through which microorganisms respond to complex environments characterized by mutagens and specific physiological-biochemical states holds significant theoretical and practical values. This study utilized Saccharomyces cerevisiae as a microbial model and highly efficient heavy ion beam (HIB) radiation as a mutagen, it revealed the time dependence of observations of survival fractions (SF) in response to HIB radiation and proposed an alternative to avoid the indeterminacy that this variable brings. Meanwhile, by incorporating an oligotrophic state into the alternative, this study constructed a dynamic map of gene expression during the fast-repair and slow-repair stages. It also highlighted the influence of trophic states on DNA repair. The findings apply to the survival-damage repair-mutation effects of single-celled microorganisms in response to various mutagens and contribute to elucidating the biological mechanisms underlying microbial survival in complex environments.

Time dependency and individual variation in human sensory irritation from acrolein - a controlled exposure study.

Acrolein is considered a risk factor for indoor air health problems due to its reactivity. An objective of the study was to investigate prevalence of sensory irritation in terms of time-dependent detection and perceived intensity of symptoms in human volunteers. Another objective was to investigate individual variation in sensory irritation. Participants (n=40) were exposed twice in an exposure chamber (15 min), once to heptane and once to acrolein and heptane. Symptoms and sensory irritation thresholds were rated continuously and 70% of the participants detected eye irritation from the acrolein exposure. A significant interaction between time and exposure (ƞp2=0.19) was identified, indicating time-dependent activation. This group also reported a higher level of stress and lower self-reported health (p<0.05). The results suggest that the eye is the primary system affected by exposure to acrolein, and that duration of exposure and perceived stress play important roles in symptom reactions due to acrolein exposure.

A carbon dot-based time-dependent color-changing room temperature phosphorescent material with facile synthesis.

Carbon dots have attracted widespread attention due to their excellent optical properties and so on and are therefore used in various fields such as anti-counterfeiting. There are many reports on carbon dot-based room-temperature phosphorescent materials, but there are still fewer reports on carbon dot-based room-temperature phosphorescent materials with time-dependent color-changing properties. In this work, a time-dependent color-changing carbon dot-based room-temperature phosphorescent material with the ability to change from green to blue was successfully prepared by a simple one-pot heating method using hydroxyurea as the only raw material. In this process, hydroxyurea is used as both a carbon and nitrogen source, and in the process of material formation, hydroxyurea also partially forms cyanuric acid as a matrix to make the carbon dots uniformly dispersed in it. By blending the ratio of the dual emission centers of the carbon dots themselves, the final effect of time-dependent color-changing is achieved by taking advantage of the intensity changes and color differences of each emission center. The present work provides new ideas for the preparation of time-dependent color-changing carbon dot-based room-temperature phosphorescent materials.

Temporal arsenic form changes dynamics and accumulation patterns in Tilia cordata Mill. seedlings: Insights into metalloid transformation and tolerance mechanisms in trees.

Arsenic (As) remediation is challenging due to the complex nature and the persistence of these metalloid compounds. While it may seem that differences between As forms influence have been extensively described, new findings challenge the previously accepted knowledge, particularly for woody plants. Therefore, this study focused on 2-year-old Tilia cordata Mill. seedlings early (0, 2, 4, 12, 24 h) and late (3, 7, 12, 18, 25, 33 days) responses during growth under: As(III), As(V) or dimethylarsinic acid (DMA) (0.3 mM). Time-dependent transformations of As forms, distribution in plants, and microbiological characteristics (actinobacteria, bacteria, fungi, enzyme activity) were investigated. The highest increase in total As content was observed in plants exposed to As(V) and As(III). Dynamic metalloid form changes in the solution and tree organs were indicated. The most phytotoxic was DMA. This form was the main factor limiting the growth and effective accumulation of As. Despite experimenting in hydroponics, microorganisms played an important role in As form transformations, suggesting the potential for microbial-assisted dendroremediation strategies. The study confirmed that trees can convert more toxic forms into less toxic ones (e.g. As(III) to phytochelatins - As(III)-(PC3)), whose presence in roots seedlings exposed to As(III) and As(V) has been identified. The formation of hydrophobic forms (e.g. dimethylarsinoyl lipid) in the roots of seedlings grown under As(V) was confirmed. It is the first discovery for trees, previously observed only in bacteria and algae. The dynamics of metalloid form changes indicated that T. cordata transforms As forms according to their needs, which may give tree species an advantage in phytoremediation techniques. It holds great promise for the potential of dendroremediation.

Diffusion MRI with free gradient waveforms on a high-performance gradient system: Probing restriction and exchange in the human brain.

The dependence of the diffusion MRI signal on the diffusion time carries signatures of restricted diffusion and exchange. Here we seek to highlight these signatures in the human brain by performing experiments using free gradient waveforms designed to be selectively sensitive to the two effects. We examine six healthy volunteers using both strong and ultra-strong gradients (80, 200 and 300 mT/m). In an experiment featuring a large set of 150 gradient waveforms with different sensitivities to restricted diffusion and exchange, our results reveal unique and different time-dependence signatures in grey and white matter. Grey matter was characterised by both restricted diffusion and exchange and white matter predominantly by restricted diffusion. Exchange in grey matter was at least twice as fast as in white matter, across all subjects and all gradient strengths. The cerebellar cortex featured relatively short exchange times (115 ms). Furthermore, we show that gradient waveforms with tailored designs can be used to map exchange in the human brain. We also assessed the feasibility of clinical applications of the method used in this work and found that the exchange-related contrast obtained with a 25-minute protocol at 300 mT/m was preserved in a 4-minute protocol at 300 mT/m and a 10-minute protocol at 80 mT/m. Our work underlines the utility of free waveforms for detecting time dependence signatures due to restricted diffusion and exchange in vivo, which may potentially serve as a tool for studying diseased tissue.

Current role and future perspectives of electroacupuncture in circadian rhythm regulation.

In recent years, in-depth research on chronobiology has been conducted, and the circadian rhythm has become a new target for the treatment of diseases. Circadian rhythms are closely related to the normal physiological functions of organisms. Increasing evidence indicates that circadian rhythm disorders are the pathological basis of diseases such as sleep disorders, depression, cardiovascular diseases, and cancer. As an economical, safe, and effective treatment method, electroacupuncture has been widely used in clinical practice. In this paper, we summarize the current literature on electroacupuncture's regulation of circadian rhythm disorders and circadian clock genes. In addition, we briefly explore the optimization of electroacupuncture intervention programmes and the feasibility of implementing electroacupuncture intervention programmes at selected times in clinical practice. We conclude that electroacupuncture may have good application prospects in circadian rhythm regulation, but this conclusion needs to be confirmed by clinical trials.

Diffusion MRI with free gradient waveforms on a high-performance gradient system: Probing restriction and exchange in the human brain.

The dependence of the diffusion MRI signal on the diffusion time carries signatures of restricted diffusion and exchange. Here we seek to highlight these signatures in the human brain by performing experiments using free gradient waveforms that are selectively sensitive to the two effects. We examine six healthy volunteers using both strong and ultra-strong gradients (80, 200 and 300 mT/m). In an experiment featuring a large set of gradient waveforms with different sensitivities to restricted diffusion and exchange (150 samples), our results reveal unique time-dependence signatures in grey and white matter, where the former is characterised by both restricted diffusion and exchange and the latter predominantly exhibits restricted diffusion. Furthermore, we show that gradient waveforms with independently varying sensitivities to restricted diffusion and exchange can be used to map exchange in the human brain. We consistently find that exchange in grey matter is at least twice as fast as in white matter, across all subjects and all gradient strengths. The shortest exchange times observed in this study were in the cerebellar cortex (115 ms). We also assess the feasibility of future clinical applications of the method used in this work, where we find that the grey-white matter exchange contrast obtained with a 25-minute 300 mT/m protocol is preserved by a 4-minute 300 mT/m and a 10-minute 80 mT/m protocol. Our work underlines the utility of free waveforms for detecting time-dependence signatures due to restricted diffusion and exchange in vivo, which may potentially serve as a tool for studying diseased tissue.

The (in)effectiveness of anticipatory vibrotactile cues in mitigating motion sickness.

The introduction of (fully) automated vehicles has generated a re-interest in motion sickness, given that passengers suffer much more from motion sickness compared to car drivers. A suggested solution is to improve the anticipation of passive self-motion via cues that alert passengers of changes in the upcoming motion trajectory. We already know that auditory or visual cues can mitigate motion sickness. In this study, we used anticipatory vibrotactile cues that do not interfere with the (audio)visual tasks passengers may want to perform. We wanted to investigate (1) whether anticipatory vibrotactile cues mitigate motion sickness, and (2) whether the timing of the cue is of influence. We therefore exposed participants to four sessions on a linear sled with displacements unpredictable in motion onset. In three sessions, an anticipatory cue was presented 0.33, 1, or 3 s prior to the onset of forward motion. Using a new pre-registered measure, we quantified the reduction in motion sickness across multiple sickness scores in these sessions relative to a control session. Under the chosen experimental conditions, our results did not show a significant mitigation of motion sickness by the anticipatory vibrotactile cues, irrespective of their timing. Participants yet indicated that the cues were helpful. Considering that motion sickness is influenced by the unpredictability of displacements, vibrotactile cues may mitigate sickness when motions have more (unpredictable) variability than those studied here.

Reliability Characteristics of Metal-Insulator-Semiconductor Capacitors with Low-Dielectric-Constant Materials.

In this study, the reliability characteristics of metal-insulator-semiconductor (MIS) capacitor structures with low-dielectric-constant (low-k) materials have been investigated in terms of metal gate area and geometry and thickness of dielectric film effects. Two low-k materials, dense and porous low-k films, were used. Experimental results indicated that the porous low-k films had shorter breakdown times, lower Weibull slope parameters and electric field acceleration factors, and weaker thickness-dependence breakdowns compared to the dense low-k films. Additionally, a larger derivation in dielectric breakdown projection model and a single Weilbull plot of the breakdown time distributions from various areas merging was observed. This study also pointed out that the porous low-k film in the irregular-shaped metal gate MIS capacitor had a larger dielectric breakdown time than that in the square- and circle-shaped samples, which violates the trend of the sustained electric field. As a result, another breakdown mechanism exists in the irregular-shaped sample, which is required to explore in the future work.

Waiting time dependence of aging.

Aging phenomena have been observed in many non-equilibrium systems such as polymers and glasses, where physical properties depend on the waiting time between the starting time of observation and the time when the temperature is changed. The aging is classified into two types on the basis of the waiting time dependence of an instantaneous relaxation time: When the relaxation time is always an increasing function of the waiting time, the aging is called Type I and when it depends on the protocol of the temperature change, the aging is called Type II. Aging of a random walk in three dimensions is investigated when the free energy landscape controlling the jump rate responds to temperature change with a delay. It is shown that the intermediate scattering function of the random walk model exhibits Type II aging. It is also shown that the relaxation time of the free energy landscape can be deduced from the waiting time dependence of the instantaneous relaxation time.

A long-run convergence analysis of aerosol precursors, reactive gases, and aerosols in the BRICS and Indonesia: is a global emissions abatement agenda supported?

This article examines the hypothesis of deterministic emissions convergence for a panel of the BRICS and Indonesia to advanced countries' emissions levels as well as to Sweden (which is a country that has clearly gone through decoupling) using a novel dataset with ten series of annual estimates of anthropogenic emissions comprising aerosols, aerosol precursor and reactive compounds, and carbon dioxide from 1820 to 2018. For that purpose, we employ four novel panel unit root tests allowing for several forms of time-dependent and state-dependent nonlinearity. The evidence supports deterministic convergence following a linear process for carbon dioxide, whereas the adjustment is asymmetric and nonlinear for carbon monoxide. Methane and nitrogen oxides exhibit logistic smooth transition converging dynamics. In contrast, black carbon, ammonia, nitrous oxide, non-methane volatile organic compounds, organic carbon, and sulfur dioxide emissions diverge. These results have implications for the abatement of greenhouse gases emissions at the global level, given the high share of emissions of the BRICS.

Diffusion MRI with pulsed and free gradient waveforms: Effects of restricted diffusion and exchange.

Monitoring time dependence with diffusion MRI yields observables sensitive to compartment sizes (restricted diffusion) and membrane permeability (water exchange). However, restricted diffusion and exchange have opposite effects on the diffusion-weighted signal, which can lead to errors in parameter estimates. In this work, we propose a signal representation that incorporates the effects of both restricted diffusion and exchange up to second order in b-value and is compatible with gradient waveforms of arbitrary shape. The representation features mappings from a gradient waveform to two scalars that separately control the sensitivity to restriction and exchange. We demonstrate that these scalars span a two-dimensional space that can be used to choose waveforms that selectively probe restricted diffusion or exchange, eliminating the correlation between the two phenomena. We found that waveforms with specific but unconventional shapes provide an advantage over conventional pulsed and oscillating gradient acquisitions. We also show that parametrization of waveforms into a two-dimensional space can be used to understand protocols from other approaches that probe restricted diffusion and exchange. For example, we found that the variation of mixing time in filter-exchange imaging corresponds to variation of our exchange-weighting scalar at a fixed value of the restriction-weighting scalar. The proposed signal representation was evaluated using Monte Carlo simulations in identical parallel cylinders with hexagonal and random packing as well as parallel cylinders with gamma-distributed radii. Results showed that the approach is sensitive to sizes in the interval 4-12 µm and exchange rates in the simulated range of 0 to 20 s - 1 , but also that there is a sensitivity to the extracellular geometry. The presented theory constitutes a simple and intuitive description of how restricted diffusion and exchange influence the signal as well as a guide to protocol design capable of separating the two effects.

Variation in the Substitution Rates among the Human Mitochondrial Haplogroup U Sublineages.

Resolving the absolute timescale of phylogenetic trees stipulates reliable estimates for the rate of DNA sequence evolution. For this end, various calibration methods have been developed and studied intensively. Intraspecific rate variation among distinct genetic lineages, however, has gained less attention. Here, we have assessed lineage-specific molecular rates of human mitochondrial DNA (mtDNA) by performing tip-calibrated Bayesian phylogenetic analyses. Tip-calibration, as opposed to traditional nodal time stamps from dated fossil evidence or geological events, is based on sample ages and becoming ever more feasible as ancient DNA data from radiocarbon-dated samples accumulate. We focus on subhaplogroups U2, U4, U5a, and U5b, the data including ancient mtDNA genomes from 14C-dated samples (n = 234), contemporary genomes (n = 301), and two outgroup sequences from haplogroup R. The obtained molecular rates depended on the data sets (with or without contemporary sequences), suggesting time-dependency. More notable was the rate variation between haplogroups: U4 and U5a stand out having a substantially higher rate than U5b. This is also reflected in the divergence times obtained (U5a: 17,700 years and U5b: 29,700 years), a disparity not reported previously. After ruling out various alternative causes (e.g., selection, sampling, and sequence quality), we propose that the substitution rates have been influenced by demographic histories, widely different among populations where U4/U5a or U5b are frequent. As with the Y-chromosomal subhaplogroup R1b, the mitochondrial U4 and U5a have been associated with remarkable range extensions of the Yamnaya culture in the Bronze Age.

Self-Limitations of Heat Release in Coupled Core-Shell Spinel Ferrite Nanoparticles: Frequency, Time, and Temperature Dependencies.

We explored a series of highly uniform magnetic nanoparticles (MNPs) with a core-shell nanoarchitecture prepared by an efficient solvothermal approach. In our study, we focused on the water dispersion of MNPs based on two different CoFe2O4 core sizes and the chemical nature of the shell (MnFe2O4 and spinel iron oxide). We performed an uncommon systematic investigation of the time and temperature evolution of the adiabatic heat release at different frequencies of the alternating magnetic field (AMF). Our systematic study elucidates the nontrivial variations in the heating efficiency of core-shell MNPs concerning their structural, magnetic, and morphological properties. In addition, we identified anomalies in the temperature and frequency dependencies of the specific power absorption (SPA). We conclude that after the initial heating phase, the heat release is governed by the competition of the Brown and Néel mechanism. In addition, we demonstrated that a rational parameter sufficiently mirroring the heating ability is the mean magnetic moment per MNP. Our study, thus, paves the road to fine control of the AMF-induced heating by MNPs with fine-tuned structural, chemical, and magnetic parameters. Importantly, we claim that the nontrivial variations of the SPA with the temperature must be considered, e.g., in the emerging concept of MF-assisted catalysis, where the temperature profile influences the undergoing chemical reactions.

Multilevel-growth modelling for the study of sustainability transitions.

Sustainability Transitions (ST) is a complex phenomenon, encompassing environmental, societal and economic aspects. Its study requires a proper investigation, with the identification of a robust indicator and the definition of a suitable method of analysis. To identify the most informative geographical boundaries for analysing ST pathways, we consider the Carbon Emission Intensity (CEI) and estimate a four-level growth model to study its pattern over time for all the EU regions. We apply this model to a novel longitudinal dataset that covers CEI data of European regions at four different geographical scales (state, areas, regions, and provinces) over a nine-year timespan. This approach aims at supporting the decision-makers in developing more effective sustainability transitions policies across Europe, especially focusing on regions and overcoming the well-known "one-size fits all" approach.•The unconditional growth model has been applied to a multi-level structure considering four levels, defined by three geographical scales and time.•The ideal structure of the model would have required five levels, but the sample size of the dataset made the application computationally unfeasible;•The application of the model allowed to identify patterns of stability and change over time of the variable amongst different geographical units.

The Time-Dependence of Three Different Modes of ELF-EMF Stimulation on LTP at Schaffer Collateral-CA1 Synapses.

Long-term potentiation (LTP) is considered the cellular basis of learning and memory. Extremely low-frequency electromagnetic fields (ELF-EMFs) are neuromodulation tools for regulating LTP. However, the temporal effects of short-term ELF-EMF stimulation on LTP are not yet known. In this study, we evaluated the time-dependent effects of 15 Hz/2 mT ELF-EMF stimulation on LTP at the Schaffer collateral-CA1 (SC-CA1) synapses in Sprague-Dawley rats. Hippocampal slices were exposed to three different modes of ELF-EMFs (sinusoidal, single-frequency pulse, and rhythm pulse) and durations (10, 20, 40, and 60 s). The baseline was recorded for 20 min and field excitatory postsynaptic potential (fEPSP) was recorded for 60 min using multi-electrode arrays (MEA) after plasticity induction using 100 Hz electrical high-frequency stimulation (HFS). Compared to the control group, the LTP decreased under three different magnetic fields and was proportional to time; that is, the longer the time, the greater the inhibition. We also compared the three magnetic fields and showed that the continuous sinusoidal magnetic field had the largest inhibitory rate of LTP, while pulsed and rhythm pulsed magnetic fields were similar. We showed that different modes of ELF-EMF stimulation had a time-dependent effect on LTP at Schaffer collateral-CA1 synapses, which provides experimental evidence for the treatment of related neurological diseases. © 2021 Bioelectromagnetics Society.

Toxicity of two representative petroleum hydrocarbons, toluene and phenanthrene, to five Atlantic coral species.

Coral reefs are keystone coastal ecosystems that can be exposed to petroleum hydrocarbons from multiple sources, and when selecting spill response methods to limit environmental damages, corals represent one of the highest valued resources for protection. Because previous research to characterize the sensitivity of coral species to petroleum hydrocarbon exposures is limited, a continuous-flow passive dosing system and toxicity testing protocol was designed to evaluate the acute effects of two representative petroleum compounds, toluene and phenanthrene, on five coral species: Acropora cervicornis, Porites astreoides, Siderastera siderea, Stephanocoenia intersepta, and Solenastrea bournoni. Using analytically confirmed exposures, sublethal and lethal endpoints were calculated for each species, and used as model inputs to determine critical target lipid body burdens (CTLBBs) for characterizing species sensitivity. Further, quantification of the time-dependent toxicity of single hydrocarbon exposures is described to provide model inputs for improved simulation of spill impacts to corals in coastal tropical environments.

Time-dependent diffusion MRI probes cerebellar microstructural alterations in a mouse model of Down syndrome.

The cerebellum is a complex system with distinct cortical laminar organization. Alterations in cerebellar microstructure are common and associated with many factors such as genetics, cancer and ageing. Diffusion MRI (dMRI) provides a non-invasive tool to map the brain structural organization, and the recently proposed diffusion-time (td )-dependent dMRI further improves its capability to probe the cellular and axonal/dendritic microstructures by measuring water diffusion at multiple spatial scales. The td -dependent diffusion profile in the cerebellum and its utility in detecting cerebellar disorders, however, are not yet elucidated. Here, we first deciphered the spatial correspondence between dMRI contrast and cerebellar layers, based on which the cerebellar layer-specific td -dependent dMRI patterns were characterized in both euploid and Ts65Dn mice, a mouse model of Down syndrome. Using oscillating gradient dMRI, which accesses diffusion at short td 's by modulating the oscillating frequency, we detected subtle changes in the apparent diffusivity coefficient of the cerebellar internal granular layer and Purkinje cell layer of Ts65Dn mice that were not detectable by conventional pulsed gradient dMRI. The detection sensitivity of oscillating gradient dMRI increased with the oscillating frequency at both the neonatal and adult stages. The td -dependence, quantified by ΔADC map, was reduced in Ts65Dn mice, likely associated with the reduced granule cell density and abnormal dendritic arborization of Purkinje cells as revealed from histological evidence. Our study demonstrates superior sensitivity of short-td diffusion using oscillating gradient dMRI to detect cerebellar microstructural changes in Down syndrome, suggesting the potential application of this technique in cerebellar disorders.