Impact of storm events on disinfection byproduct precursors in a drinking water source in the Northeastern United States

Storm events play a crucial role in organic matter transport within watersheds and can increase the concentration and alter the composition of NOMs and DBP formation potential. To assess the impact that storm events can have on drinking water quality, samples were collected and analyzed across four storm events in the Neversink River, Catskill region, New York in 2019 and 2022. Source water natural organic matter (NOM) was characterized, and the change of NOM quality was evaluated due to storm impacts. During storm events, a high level of NOM mobilization is initiated by heavy precipitation causing overland flow and a rise in the water table. In this way, storms result in increased access to stored NOM pools that are generated during inter-storm periods. A significant correlation was observed between several organic water quality parameters such as UV absorbance (UV254), dissolved organic carbon (DOC) and chlorine demand. Precursors for the total trihalomethanes (TTHM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) exhibited comparable patterns with UV254, DOC, and chlorine demand for four storms. Despite the potential for increased dilution resulting from higher discharges, all organic water quality parameters, including yields of disinfection byproducts (i.e., DBP precursors), exhibited elevated concentrations during periods of higher flows. Three of the four storms showed hysteresis patterns with higher observed concentrations of organic constituents in the falling limb of the hydrographs. Precursors for the nitrogenous DBPs (N-DBPs) were proportional to the DOC for all four storms. The coefficient of determination (R2) for TTHM, DCAA, TCAA with UV254 is higher (R2 0.92-0.98) than corresponding correlations with DOC (R2 0.89-0.92). The R2 for UV254 showed the following hierarchy: DCAA≈TCAA>TTHM. Additionally, the R2 for DOC and specific ultraviolet absorbance (SUVA) had the following hierarchy: DCAA>TCAA>TTHM and TCAA>DCAA>TTHM respectively. A significant correlation between UV254 and DOC (R = 0.99) for all storms was observed. Chlorine demand also yielded a strong correlation (R = 0.91∼0.98) with UV254 and DOC. This research indicates that a significant and disproportionate export of NOM to source waters occurs during storm events compared to baseflow conditions. Consequently, it is recommended for drinking water treatment facilities to reassess chlorine dosages during these events. Treatment plants can employ UV254 as a tool to determine appropriate chlorine dosages, aiming to mitigate DBP formation in treated waters.

Monitoring soil moisture in winter wheat with crop water stress index based on canopy-air temperature time lag effect

Crop water stress index (CWSI) has been widely used in soil moisture monitoring. However, the influence of the time lag effect between canopy temperature and air temperature on the accuracy of soil moisture monitoring with different CWSI models has not been further investigated. Therefore, based on the continuous record of canopy temperature and air temperature, this study explored the influence of canopy-air temperature hysteresis on the diagnosis of soil moisture with three CWSI models (CWSIT-theoretical, CWSIE-empirical, CWSIH-hybrid). The results show (1) the peak time of canopy temperature was ahead of that of air temperature, and the lag time varied under different soil moisture conditions. When the soil moisture was seriously deficient, the lag time decreased. However, from jointing-heading period to filling-ripening period, the lag time became longer. (2) The values of CWSIT, CWSIE, and CWSIH decreased when the time lag effect was considered. In jointing-heading period, heading-filling period, and filling-ripening period, CWSIT had the highest accuracy in soil moisture monitoring without the consideration of the time lag effect. When the time lag effect was considered, the monitoring accuracy of CWSIE and CWSIH was greatly improved and higher than that of CWSIT, while that of CWSIT was reduced. The findings provided a basis for further improving the accuracy of soil moisture monitoring with CWSI models.

Unveiling heterogeneity of hysteresis in perovskite thin films

The phenomenon of current-voltage hysteresis observed in perovskite-based optoelectronic devices is a critical issue that complicates the accurate assessment of device parameters, thereby impacting performance and applicability. Despite extensive research efforts aimed at deciphering the origins of hysteresis, its underlying causes remain a subject of considerable debate. By employing nanoscale investigations to elucidate the relationship between hysteresis and morphological characteristics, this study offers a detailed exploration of photocurrent-voltage hysteresis at the nanoscale within perovskite optoelectronic devices. Through the meticulous analysis of localized I-V curve arrays, our research identifies two principal hysteresis descriptors, uncovering a predominantly inverted hysteresis pattern in 87% of the locations examined. This pattern is primarily attributed to the energetic barrier encountered at the interface between the probe and the perovskite material. Our findings underscore the pronounced heterogeneity and grain-dependent variability inherent in hysteresis behavior, evidenced by an average Hysteresis Index value of 0.24. The investigation suggests that the localized hysteresis phenomena cannot be exclusively attributed to either photocharge collection processes or organic cation migration at grain boundaries. Instead, it appears significantly influenced by localized surface trap states, which play a pivotal role in modulating electron and hole current dynamics. By identifying the key factors contributing to hysteresis, such as localized surface trap states and their influence on electron and hole current dynamics, our findings pave the way for targeted strategies to mitigate these effects. This includes the development of novel materials and device architectures designed to minimize energy barriers and enhance charge carrier mobility, thereby improving device performance and longevity. This breakthrough in understanding the microscale mechanisms of hysteresis underscores the critical importance of surface/interface defect trap passivation in mitigating hysteretic effects, offering new pathways for enhancing the performance of perovskite solar cells.

Establishment of a Biaxial Testing System for Characterization of Right Ventricle Viscoelasticity Under Physiological Loadings

PURPOSE

Prior studies have indicated an impact of cardiac muscle viscoelasticity on systolic and diastolic functions. However, the studies of ventricular free wall viscoelasticity, particularly for that of right ventricles (RV), are limited. Moreover, investigations on ventricular passive viscoelasticity have been restricted to large animals and there is a lack of data on rodent species. To fill this knowledge gap, this study aims to develop a biaxial tester that induces high-speed physiological deformations to characterize the passive viscoelasticity of rat RVs.

METHODS

The biaxial testing system was fabricated so that planar deformation of rat ventricle tissues at physiological strain rates was possible. The testing system was validated using isotropic polydimethylsiloxane (PDMS) sheets. Next, viscoelastic measurements were performed in healthy rat RV free walls by equibiaxial cyclic sinusoidal loadings and stress relaxation.

RESULTS

The biaxial tester's consistency, accuracy, and stability was confirmed from the PDMS samples measurements. Moreover, significant viscoelastic alterations of the RV were found between sub-physiological (0.1 Hz) and physiological frequencies (1-8 Hz). From hysteresis loop analysis, we found as the frequency increased, the elasticity and viscosity were increased in both directions. Interestingly, the ratio of storage energy to dissipated energy (Wd/Ws) remained constant at 0.1-5 Hz. We did not observe marked differences in healthy RV viscoelasticity between longitudinal and circumferential directions.

CONCLUSION

This work provides a new experimental tool to quantify the passive, biaxial viscoelasticity of ventricle free walls in both small and large animals. The dynamic mechanical tests showed frequency-dependent elastic and viscous behaviors of healthy rat RVs. But the ratio of dissipated energy to stored energy was maintained between frequencies. These findings offer novel baseline information on the passive viscoelasticity of healthy RVs in adult rats.

High-performance liquid chromatographic enantioseparation of azole analogs of monoterpene lactones and amides focusing on the separation characteristics of polysaccharide-based chiral stationary phases

High-performance liquid chromatography-based enantioseparation of newly prepared azole analogs of monoterpene lactones and amides was studied. Effects of additives and mobile phase composition were evaluated both in normal and polar organic modes. Applying amylose tris-(3,5-dimethylphenylcarbamate) selector in normal and polar organic modes acid and base additives were found to affect the peak profiles, without significantly influencing the enantiorecognition ability of the studied selector. In most cases, differences observed in retention times and enantioselectivities were lower than 10 and 20 % under normal phase and polar organic conditions, respectively. Under normal phase conditions decreased retention was observed for all the studied analytes with increased eluent polarity. Interestingly, enantioselectivity was only slightly (<10 %) influenced by the variation in the n-hexane/2-propanol ratio between 80/20 and 20/80 v/v. In polar organic mode, five different neat solvents (acetonitrile, methanol, ethanol, 1-propanol, and 2-propanol) were tested, and the best results were obtained with acetonitrile and ethanol in the case of Lux Amylose-1 column with enantioresolutions most often above 2. Based on results obtained with amylose and cellulose-based columns the amylose tris-(3,5-dimethylphenylcarbamate) selector is found to offer a superior performance both in normal and polar organic modes. When evaluating the possible effects of the selector immobilization, no striking differences were found in the normal phase. Usually, enantioselectivities and resolutions were higher (10-20 %), while retention factors of the first peaks were lower (20-30 %), on the coated-type column. In contrast, in polar organic mode, the retention characteristics and enantiorecognition ability of the coated and immobilized selectors were heavily affected by the nature of the polar solvent. Special attention has been paid to the history-dependent behavior of polysaccharide-based selectors. A confidence interval-based evaluation is suggested to help comparison of the histereticity observed in different systems. Several examples are shown to confirm that the recently discovered hysteresis is a common characteristic of polysaccharide-based selectors.

A Comparative Study of Ex-Vivo Murine Pulmonary Mechanics Under Positive- and Negative-Pressure Ventilation

Increased ventilator use during the COVID-19 pandemic resurrected persistent questions regarding mechanical ventilation including the difference between physiological and artificial breathing induced by ventilators (i.e., positive- versus negative-pressure ventilation, PPV vs NPV). To address this controversy, we compare murine specimens subjected to PPV and NPV in ex vivo quasi-static loading and quantify pulmonary mechanics via measures of quasi-static and dynamic compliances, transpulmonary pressure, and energetics when varying inflation frequency and volume. Each investigated mechanical parameter yields instance(s) of significant variability between ventilation modes. Most notably, inflation compliance, percent relaxation, and peak pressure are found to be consistently dependent on the ventilation mode. Maximum inflation volume and frequency note varied dependencies contingent on the ventilation mode. Contradictory to limited previous clinical investigations of oxygenation and end-inspiratory measures, the mechanics-focused comprehensive findings presented here indicate lung properties are dependent on loading mode, and importantly, these dependencies differ between smaller versus larger mammalian species despite identical custom-designed PPV/NPV ventilator usage. Results indicate that past contradictory findings regarding ventilation mode comparisons in the field may be linked to the chosen animal model. Understanding the differing fundamental mechanics between PPV and NPV may provide insights for improving ventilation strategies and design to prevent associated lung injuries.

The oscillation of mitotic kinase governs cell cycle latches in mammalian cells

The mammalian cell cycle alternates between two phases - S-G2-M with high levels of A- and B-type cyclins (CycA and CycB, respectively) bound to cyclin-dependent kinases (CDKs), and G1 with persistent degradation of CycA and CycB by an activated anaphase promoting complex/cyclosome (APC/C) bound to Cdh1 (also known as FZR1 in mammals; denoted APC/C:Cdh1). Because CDKs phosphorylate and inactivate Cdh1, these two phases are mutually exclusive. This 'toggle switch' is flipped from G1 to S by cyclin-E bound to a CDK (CycE:CDK), which is not degraded by APC/C:Cdh1, and from M to G1 by Cdc20-bound APC/C (APC/C:Cdc20), which is not inactivated by CycA:CDK or CycB:CDK. After flipping the switch, cyclin E is degraded and APC/C:Cdc20 is inactivated. Combining mathematical modelling with single-cell timelapse imaging, we show that dysregulation of CycB:CDK disrupts strict alternation of the G1-S and M-G1 switches. Inhibition of CycB:CDK results in Cdc20-independent Cdh1 'endocycles', and sustained activity of CycB:CDK drives Cdh1-independent Cdc20 endocycles. Our model provides a mechanistic explanation for how whole-genome doubling can arise, a common event in tumorigenesis that can drive tumour evolution.

Analyzing the contribution of gully erosion to land degradation in the upper Blue Nile basin, Ethiopia

Soil erosion has become a worldwide problem that threatens the environment and the future of economic and social development. The purpose of this study is to investigate the contribution of steep slopes and gullies to erosion in high precipitation tropical areas of the Ethiopian highlands. A trapezoidal weir was installed at the head and tail of the gully to monitor the discharge and sediment concentration from 2017 to 2020. Sediment yield and runoff are heavily influenced by the amount and timing of precipitation. The coefficients of variation for total sediment loads ranged from 65.1 to 96.1% at the head and 17.1-78.1% at the tail; the lowest coefficients were found in 2018 and the highest in 2020. Furthermore, 85% of the sediment at the tail comes from the gully, according to the four-year sediment budget. Further, a hysteretic analysis of suspended sediment concentration and runoff revealed that hilly sediment sources are limited (clockwise), then sediment can be transported through the gully via bank failures (counterclockwise). Study findings contributed to a classification of runoff patterns and an investigation of suspended sediment dynamics. In the gully tail, sediment yield was higher than in the head, suggesting gully sediment contributed more to sediment yield than large upland catchments. As a result of the study, we have been able to develop practical recommendations for managing gully erosion in the future.

Changes in air dose rates due to soil moisture content in the Fukushima prefecture forests

Radionuclides released and deposited because of the 2011 Fukushima Dai-ichi Nuclear Power Plant accident caused an increase in air dose rates in Fukushima Prefecture forests. Although an increase in air dose rates during rainfall was previously reported, the air dose rates in the Fukushima forests decreased during rainfall. This study aimed to develop a method to estimate rainfall-related changes in air dose rates, even in the absence of soil moisture data, in Namie-Town and Kawauchi-Village, Futaba-gun, Fukushima Prefecture. Moreover, we examined the relationship between preceding rainfall (Rw) and soil moisture content. The air dose rate was estimated by calculating the Rw in Namie-Town from May to July 2020. We found that the air dose rates decreased with increasing soil moisture content. The soil moisture content was estimated from Rw by combining short-term and long-term effective rainfall using half-live values of 2 h and 7 d and considering the hysteresis of water absorption and drainage processes. Furthermore, the soil moisture content and air dose rate estimations showed a good agreement with coefficient of determination (R2) scores >0.70 and >0.65, respectively. The same method was tested to estimate the air dose rates in Kawauchi-Village from May to July 2019. At the Kawauchi site, variation in estimated value is relatively large due to the presence of water repellency in dry conditions, and the amount of 137Cs inventory was low, so estimating air dose from rainfall remained a challenge. In conclusion, rainfall data were successfully used to estimate soil moisture and air dose rates in areas with high 137Cs inventories. This leads to the possibility of removing the influence of rainfall on measured air dose rate data and could contribute to the improvement of methods currently used to estimate the external air dose rates for humans, animals, and terrestrial forest plants.

Land resource management patterns and urban air quality-evidence from the "land for development" model with Chinese characteristics

Based on panel data of 282 prefecture-level and above cities in China from 2013 to 2020, this paper investigates the impact and transmission paths of the "LFD" land disposal model on urban air quality at the theoretical and empirical levels using dynamic fixed-effects and dynamic spatial Durbin models. The results show that the way land is allocated in a city has a lagging and long-term impact on air quality not only locally but also in neighboring cities. The type of land supply by local governments to different sectors is an important pathway to influence urban air quality. Extended analysis shows that land market reforms in China can significantly reduce urban air quality index (AQI) and effectively mitigate urban air quality, with long-term effects. This paper provides a theoretical and scientific basis for correcting the mismatch of land resources and promoting urban ecological environment in China.

Exploitation of the enantioselectivity space of coated amylose tris(3,5-dimethylphenylcarbamate) in mixtures of 2-propanol and acetonitrile

Chiral stationary phases (CSPs) with coated amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) selector have long been recognized for their excellent chiral recognition ability in liquid chromatography. The conformational versatility behind this feature is the source of their known hysteretic behavior, which has been previously observed in polar organic (PO) mode eluents containing 2-propanol (IPA). Mixtures of IPA and acetonitrile (MeCN), a typical PO mode eluent system, have not been examined in this aspect yet, even though hysteresis is promising for finding unique unexplored enantioselectivities. Not only was the hysteresis detectable on ADMPC using mixtures of IPA and MeCN, but it was the typical behavior in a diverse set of test compounds. The difference in the retention time of the same analyte under conditions which only differed in the eluent history on the column can go up to 20-fold. The assumed hindered conformational changes of the selector were reflected in retention drift at certain eluent compositions. On the two sides of the transitions, distinct, useful states of the selector were detected. A series of IPA - MeCN compositions with defined pretreatment was selected and recommended as an extension of the preliminary, first choice method screening set that used only alcohols. The incorporation of a solvent possessing substantially different characteristics enhances the potential in practical applications, while keeping the technical simplicity. Stability and robustness of the additional states of the CSP were characterized. The examined columns of different brands shared the observed behavior. Kinetic stability of a column state is adequate for successful application. The evaluated states of ADMPC provide multiple enantiorecognition potential by using mixtures of IPA and MeCN also considering the pretreatment of the column. Unprecedented double and triple elution order reversals along the composition range supported the versatility of the available states. Our findings further enhance the usefulness of ADMPC-containing CSPs. We provide instructions for the application of the widespread chiral selector in common eluent mixtures to avoid pitfalls regarding reproducibility and robustness.

An index for inferring dominant transport pathways of solutes and sediment: Assessing land use impacts with high-frequency conductivity and turbidity sensor data

Land use change threatens aquatic ecosystems through freshwater salinization and sediment pollution. Effective river management requires an understanding of the dominant hydrologic pathways of sediment and solute delivery. To address this, we applied hysteresis analysis, hydrograph separation, and linear regression to hundreds of events across a decade of specific conductance and turbidity data from three streams along a rural-to-urban gradient. Thereafter, we developed an index (β_runoff^') to quantify the relative influence of surface runoff to event-scale suspended sediment generation, where a value of '1' indicates complete alignment of suspended sediment generation with the temporal structure of runoff whereas '0' indicates total alignment with baseflow. Solute hysteresis results showed a predominance of dilution for the rural and mixed-use streams irrespective of road salt presence. On the other hand, urban stream behavior shifted from dilution to flushing following salt application, which was largely driven by greater runoff coefficients and the connectivity of distal solutes to the stream corridor. The newly developed index (β_runoff^') indicated that suspended sediment dynamics were more aligned with runoff in all three streams: rural stream (β_runoff^' = 0.70), mixed stream (β_runoff^' = 0.57), and urban stream (β_runoff^' = 0.64). The relative importance of baseflow to sediment generation grows slightly in urbanizing streams, as impervious surfaces disconnect upland sediment, which would otherwise transport with runoff, while piston-flow baseflow erodes exposed streambanks. Our findings emphasize the need to consider the impact of human modification of the landscape on solute and sediment transport in freshwater systems for effective water quality management. Further, our β_runoff^' index provides a useful tool for assessing the relative influence of surface runoff on event-scale solute or sediment generation in streams, supporting river management and conservation efforts.

Hybrid controller for mid-range mid-power audio application

A major reason for compromised audio quality with a coil-type loudspeaker is its complex impedance profile, which disturbs the intended algebraic linearity or linear phase behavior between the amplifier input and speaker driving force. Though switch-mode amplifiers are increasingly preferred in such audio systems owing to their superior energy efficiency, their inherent non-linearity and finite internal impedance further degrade audio reproduction. This paper investigates the effect of stated impedance on the loudspeaker driving current, hence on the loudspeaker driving force, and proposes a Hybrid controller-amplifier to enhance the proportionality between the audio reference and driving force without compromising on loudspeaker damping. The Hybrid amplifier combines a sliding mode controlled amplifier (SMCA) and a linear controller, designed after exhaustive modeling of the input-output behavior of the SMCA and best-fit approximation of the loudspeaker impedance. An 8 W, 500 Hz to 20 kHz prototype of the proposed amplifier is fabricated on the basis of the presented design. Time and frequency-domain results obtained with the experimental hardware are presented to validate the performance improvement.

Experimental investigation of water retention curves of municipal solid wastes with different paper contents, dry unit weights and degrees of biodegradation

This paper investigates the drying and wetting water retention curves (WRCs) of municipal solid wastes (MSWs) with different paper contents, dry unit weights and degrees of biodegradation (DOBs). Fresh synthetic samples were prepared based on the field composition of the MSWs at Mugga Lane Landfill, the Australian Capital Territory (ACT), Australia. The degraded samples were prepared in simulators with MSWs of different initial dry unit weights and decomposition periods with leachate recirculation. The water retention curves (WRCs) of the MSWs were determined using pressure plate tests, in both drying and wetting phases. The outflow from MSWs was analysed using Gardner's method to obtain the unsaturated hydraulic conductivity. The results indicate that the WRCs of the MSWs are greatly affected by the DOB, paper content and dry unit weight. When DOB < 30 %, as DOB increases, the air-entry pressure of MSWs with paper increases, and the residual moisture content decreases regardless of paper content. With DOB > 30 %, the air entry pressure and residual water content depend on the balance between organic matter and highly decomposed organic constituents. The paper content affects the WRCs of MSWs due to its water retention capacity and change in the particle size distribution with decomposition. The increase in the dry unit weight of MSWs significantly increases the air entry pressure and residual moisture content, similar to the borehole samples with combined effects of biodegradation and increase in stress level from literature. Hysteresis effects have been observed during the drying and wetting of MSWs. The hysteresis of WRCs increases with the paper content and DOB.

Experimental and simulated distribution and interaction of water in cellulose esters with alkyl chain substitutions

This study investigated the effect of the average length of substituted side chains in different cellulose esters on water sorption and the water association mechanism. For this purpose, a set of esters with a similar total degree of substitution was selected: cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. Dynamic vapor sorption was used to determine the effect of the side chain length on sorption, desorption, and the occurrence of water clustering. Since water association in the structure was of interest, molecular dynamics simulations were performed on cellulose acetate and cellulose acetate propionate. This study showed that cellulose acetate appears to be water-sensitive and experiences hysteresis upon water sorption, which was attributed to structural changes. The simulations also showed that water is screened out by the side chains and forms intermolecular hydrogen bonds, primarily to the carbonyl oxygen rather than the residual hydroxyl groups.

Towards modern understanding of the Achilles tendon properties in human movement research

The Achilles tendon (AT) is the strongest tendon in humans, yet it often suffers from injury. The mechanical properties of the AT afford efficient movement, power amplification and power attenuation during locomotor tasks. The properties and the unique structure of the AT as a common tendon for three muscles have been studied frequently in humans using in vivo methods since 1990's. As a part of the celebration of 50 years history of the International Society of Biomechanics, this paper reviews the history of the AT research focusing on its mechanical properties in humans. The questions addressed are: What are the most important mechanical properties of the Achilles tendon, how are they studied, what is their significance to human movement, and how do they adapt? We foresee that the ongoing developments in experimental methods and modeling can provide ways to advance knowledge of the complex three-dimensional structure and properties of the Achilles tendon in vivo, and to enable monitoring of the loading and recovery for optimizing individual adaptations.

Perceptual warping exposes categorical representations for speech in human brainstem responses

The brain transforms continuous acoustic events into discrete category representations to downsample the speech signal for our perceptual-cognitive systems. Such phonetic categories are highly malleable, and their percepts can change depending on surrounding stimulus context. Previous work suggests these acoustic-phonetic mapping and perceptual warping of speech emerge in the brain no earlier than auditory cortex. Here, we examined whether these auditory-category phenomena inherent to speech perception occur even earlier in the human brain, at the level of auditory brainstem. We recorded speech-evoked frequency following responses (FFRs) during a task designed to induce more/less warping of listeners' perceptual categories depending on stimulus presentation order of a speech continuum (random, forward, backward directions). We used a novel clustered stimulus paradigm to rapidly record the high trial counts needed for FFRs concurrent with active behavioral tasks. We found serial stimulus order caused perceptual shifts (hysteresis) near listeners' category boundary confirming identical speech tokens are perceived differentially depending on stimulus context. Critically, we further show neural FFRs during active (but not passive) listening are enhanced for prototypical vs. category-ambiguous tokens and are biased in the direction of listeners' phonetic label even for acoustically-identical speech stimuli. These findings were not observed in the stimulus acoustics nor model FFR responses generated via a computational model of cochlear and auditory nerve transduction, confirming a central origin to the effects. Our data reveal FFRs carry category-level information and suggest top-down processing actively shapes the neural encoding and categorization of speech at subcortical levels. These findings suggest the acoustic-phonetic mapping and perceptual warping in speech perception occur surprisingly early along the auditory neuroaxis, which might aid understanding by reducing ambiguity inherent to the speech signal.

Source availability and hydrological connectivity determined nitrate-discharge relationships during rainfall events in karst catchment as revealed by high-frequency nitrate sensing

Karst terrain seasonal monsoonal rainfall is often associated with high concentrations of nitrate-N in streams draining agricultural land. Such high concentrations can pose problems for environmental and human health. However, the relationship between rainfall events that mobilize nitrate and resulting nitrate export remains poorly understood in karst terrain. To better understand the processes that drive nitrate dynamics during rainfall events, the characteristics of individual rainfall events were analyzed using sensor technology. Thirty-eight rainfall events were separated from the high-frequency dataset spanning 19 months at a karst spring site. The results revealed that nitrate-discharge (N-Q) hysteresis in 79% of rainfall events showed anticlockwise hysteresis loop patterns, indicating nitrate export from long distances within short event periods. Karstic hydrological connectivity and source availability were considered two major determining factors of N-Q hysteresis. Gradual increase in hydrological connectivity during intensive rainfall period accelerated nitrate transportation by karst aquifer systems. Four principal components (PCs, including antecedent conditions PC1&3 and rainfall characteristics PC2&4 explained 82% of the cumulative variance contribution to the rainfall events. Multiple linear regression of four PCs explained more than 50% of the variation of nitrate loading and amplitude during rainfall events, but poorly described nitrate concentrations and hydro-chemistry parameters, which may be influenced by other factors, e.g., nitrate transformation, fertilization time and water-rock interaction. Although variation of N concentration during event flow is evident, accounting for antecedent conditions and rainfall factors can help to predict rainfall event N loading during rainfall events. Pollution of the karstic catchment occurred by a flush of nitrate input following rainfall events; antecedent and rainfall conditions are therefore important factors to consider for the water quality management. Reducing source availability during the wet season may facilitate to reduction of nitrogen loading in similar karst areas.

Hysteresis in motor and language production

Hysteresis in motor planning and syntactic priming in language planning refer to the influence of prior production history on current production behaviour. Computational efficiency accounts of action hysteresis and theoretical accounts of syntactic priming both argue that reusing an existing plan is less costly than generating a novel plan. Despite these similarities across motor and language frameworks, research on planning in these domains has largely been conducted independently. The current study adapted an existing language paradigm to mirror the incremental nature of a manual motor task to investigate the presence of parallel hysteresis effects across domains. We observed asymmetries in production choice for both the motor and language tasks that resulted from the influence of prior history. Furthermore, these hysteresis effects were more exaggerated for subordinate production forms implicating an inverse preference effect that spanned domain. Consistent with computational efficiency accounts, across both task participants exhibited reaction time savings on trials in which they reused a recent production choice. Together, these findings lend support to the broader notion that there are common production biases that span both motor and language domains.

Adsorption and desorption characteristics of arsenic in calcareous soils as a function of time; equilibrium and thermodynamic study

Irrigation of carbonate-rich agricultural soils with arsenic (As)-contaminated water leads to the accumulation of As in these soils. In this regard, there is an opportunity to adsorb and fix the As in soil and decrease the As transportation to the plants and subsequently the human food chain. So, the present study aimed to investigate the adsorption-desorption characteristics of As in calcareous soils and the potential of As fixation over time. First, to achieve this purpose, 53 soil samples were gathered from the study site and after the laboratory analysis, the soils were categorized into four groups based on their physicochemical properties. Then, four representative samples of these groups were selected, namely soil 1, soil 2, soil 3, and soil 4. Afterward, the As adsorption-desorption was investigated in a lab-scale batch experiment. Next, the effect of age was assessed by incubating the As-adsorbed soils for 60 days, and to study the impact of temperature, the adsorption was performed at four temperature levels (10, 20, 30, and 40 °C). Finally, the isotherm models were fitted to experimental data, and the amount of loosely and tightly held As was quantified. Results revealed that the As adsorption isotherms were L-type, in which As adsorption increased with the increase of As loading. The double-site Langmuir (DSL) estimated that a limited amount of As was adsorbed on high-energy surfaces and a large amount of As was adsorbed on low-energy surfaces. Desorption results showed that a significant amount of As desorbed immediately; however, the desorption significantly decreased with the increase of age, especially at low equilibrium concentrations. By aging the loosely held As transformed into non-labile forms so that in soils 1, 2, 3, and 4, the fraction of As adsorbed on high-energy surfaces increased from 72.5, 93.2, 63.2, and 123 mg/kg to 167, 141, 70.6, and 196 mg/kg, respectively, and the fraction of As adsorbed on low-energy surfaces decreased from 397, 256, 202, and 317 mg/kg to 182, 238, 173, and 172 mg/kg, respectively (after aging for 60 days). Aging proved to be a promising solution for decreasing As transport into the human food chain and could be employed for crops with longer irrigation cycles. ΔH_ad values were positive and varied from 9.26 to 13.0 kJ/mol, confirming the endothermic nature of adsorption. ΔG_ad values were negative and varied from - 18.8 to - 22.8 kJ/mol at all temperatures, demonstrating the spontaneous nature of adsorption.

Total and dissolved phosphorus losses from agricultural headwater streams during extreme runoff events

Eutrophication continues to be a concerning global water quality issue. Managing and mitigating harmful algal blooms demands clear information on the conditions promoting large phosphorus losses from contributing watersheds. Of particular concern is the amount and form of phosphorus loading to receiving water bodies during extreme runoff events, which are expected to increase in frequency due to climate change. Five years (2015 to 2020) of water quantity and quality data from 11 agricultural watersheds in the lower Great Lakes basin were analyzed and used to model total and dissolved phosphorus losses. This study aimed to assess temporal dynamics in phosphorus concentrations and losses over runoff events covering a wide range of hydrologic conditions and to quantify their relative importance on annual phosphorus losses. Event concentration-discharge relationships for total and dissolved phosphorus were hysteretic and had contrasting dominant patterns across watersheds. The proportion of annual phosphorus losses during events was highly variable between watersheds, accounting for 47-94 %. Extreme events were particularly impactful: as few as three events per year were found to be responsible for nearly half of total phosphorus (20-50 %) and total dissolved phosphorus (14-44 %) losses. Variability in total and dissolved phosphorus losses and concentrations over a wide range of flow conditions suggests that event magnitude is an important control on the relative mobility of particulate and dissolved phosphorus fractions. This study showed that insights into nutrient dynamics and phosphorus budgets in the lower Great Lakes basin and agriculture dominated environments more broadly can be gained by assessing event nutrient losses with respect to flow conditions and patterns in concentration-discharge relationships.

Catalytic behavior of gold nanoparticles supported on a TiO2-Al2O3 mixed oxide for CO oxidation at low temperature

The present work highlights the versatility of a TiO₂-Al₂O₃ mixed oxide bearing highly dispersed gold nanoparticles that was applied in the CO oxidation reaction at room temperature. The TiO₂, Al₂O₃, and TiO₂-Al₂O₃ supports were synthesized by the sol-gel method, while gold nanoparticles were added by the deposition-precipitation with urea method using a theoretical Au loading of 2 wt.%. A promotional effect of the TiO₂-Al₂O₃ support on the activity of gold catalysts with respect to TiO₂ and Al₂O₃ was observed; Au/TiO₂-Al₂O₃ showed outstanding CO oxidation, being active from 0 °C and stable throughout a 24-h test. As for the alumina content (5, 10, and 15 wt.%) in TiO₂, it improved the textural properties by retarding the crystal growth and anatase-rutile phase transformation of TiO₂, suppressing the deposition of carbon on the catalyst surface and stabilizing the Au nanoparticles even at high temperatures. Gold was highly dispersed with nanoparticle sizes ranging from 1 to 2 nm when H₂ was used to treat thermally the Au/TiO₂-Al₂O₃, Au/TiO_2, and Au/Al₂O₃ materials. In addition, the XPS technique helped elicit that Au⁰ and Au¹⁺ boosted their interaction with the TiO₂, Al₂O₃, and TiO₂-Al₂O₃ supports by means of charge transfer, which resulted in outstanding CO oxidation activity from 0 °C. Likewise, the key factors that control the peculiar catalytic performance in the CO oxidation reaction are discussed, which represents a step forward in the versatility behavior of gold catalysts supported on mixed oxide catalysts.

Practical Aspects of Instantaneous Magnetization Power Functions of Silicon Iron Laminations

Magnetic energy loss P of SiFe steel represents a key factor for the efficiency of soft magnetic machine cores. Traditionally, they are operated with 50 Hz (or 60 Hz), a frequency value that yields rather balanced portions of hysteresis loss and eddy current loss. In equivalent circuits of transformers, P tends to be represented by a magnetic power resistance R _M, as a constant. For the most important case of sinusoidal induction B of 50 Hz, this would correspond to an instantaneous magnetization power function p(t) that is sinusoidal as well, however, with 100 Hz (or 120 Hz). On the other hand, from complex, non-linear mechanisms of hysteresis, it is obvious that p(t) should be strongly non-sinusoidal, even for exactly sinusoidal B(t). So far, almost all corresponding instantaneous investigations were restricted to calculated modelling of loss portions and transient modelling. On the other hand, for the first time, the present study was focussed on functions p(t) as measured at IEC-standardized samples of industrially relevant steel. Practical evaluations are discussed with respect to the revealed "history" of magnetization processes, as well as for product characterization. For these tasks, a novel digitized "Low-mass Single Sheet Tester" was developed that was applied for both non-oriented steel (NO) and grain-oriented steel (GO), for 50 Hz. Interpretations proved to be favoured by relating p(t) to total P, according to an instantaneous power ratio. As a result, both steel types revealed strongly non-sinusoidal power functions, with short durations of negative p. Negative p proved to be most pronounced for NO steel, as a measure for the onset of reversible turns of atomic moments. As a consequence, p(t) comprises strong upper harmonics of 200 Hz and even 300 Hz. Based on theoretical considerations, we split p(t) in a dissipative loss power function p _L(t) and in a potential energy power function p _P(t). Finally, we used p(t) to determine the corresponding power resistance R _M(t) that proves to be a distinctly nonlinear function as well. It resembles a rectified co-sinus, also exhibiting short negative spikes that reflect the crystallographic dis-orientation of the polycrystalline material.

Hysteresis light curves: a protocol for characterizing the time dependence of the light response of photosynthesis

Photosynthesis vs. light curves (LCs) have played a central role in photosynthesis research for decades. They are the commonest form of describing how photosynthesis responds to changes in light, being frequently used for characterizing photoacclimation. However, LCs are often interpreted exclusively regarding the response to light intensity, the effects of time of exposure not being explicitly considered. This study proposes the use of 'hysteresis light curves' (HLC), an experimental protocol focused on the cumulative effects of light exposure to obtain information on the time dependence of photosynthetic light responses. HLC are generated by exposing samples to a symmetrical sequence of increasing and decreasing light levels. The comparison of the light-increasing and the light-decreasing phases allows the quantification of the hysteresis caused by high-light exposure, the magnitude and direction of which inform on the activation, and subsequent relaxation of high-light-induced photosynthetic processes. HLCs of the chlorophyll fluorescence indices rETR (relative electron transport rate of photosystem II) and Y(NPQ) (index of non-photochemical quenching) were measured on cyanobacteria, algae, and plants, with the aim of identifying main patterns of hysteresis and their diversity. A non-parametric index is proposed to quantify the magnitude and direction of hysteresis in HLCs of rETR and Y(NPQ). The results of this study show that HLCs can provide additional relevant information on the time dependence of the light response of photosynthetic samples, not obtainable from conventional LCs, useful for phenotyping photosynthetic traits, including photoacclimation state and kinetics of light activation and relaxation of electron flow and energy dissipation processes.

Phase transitions in porous media

The full quasistatic thermomechanical system of PDEs, describing water diffusion with the possibility of freezing and melting in a visco-elasto-plastic porous solid, is studied in detail under the hypothesis that the pressure-saturation hysteresis relation is given in terms of the Preisach hysteresis operator. The resulting system of balance equations for mass, momentum, and energy coupled with the phase dynamics equation is shown to admit a global solution under general assumptions on the data.

Active disturbance rejection control for nanopositioning: A robust U-model approach

Hysteresis severely reduces positioning performance of a piezoelectric nanopositioning stage. Linear active disturbance rejection control (LADRC) is a practical solution to improve the positioning accuracy. However, the PD controller utilized in the LADRC is not effective enough to suppress the uncancelled total disturbance, and high-order pure integrators are difficult to be stabilized just by a PD controller. In this work, a robust U-model active disturbance rejection control (RUADRC) is proposed by incorporating the core idea of the U-model control and the Glover-McFarlane control. Then, the controlled plant can be dynamically transformed to a unit. Difficulties in stabilizing high-order pure integrators are decreased, the phase lag between the input and output of a controlled plant is reduced, and the closed-loop responses is sped up. In addition, the influence of both inaccurate total disturbance estimation and imperfect approximation is also minimized by the Glover-McFarlane control Closed-loop stability, steady-state tracking error, and the phase advantage of the RUADRC have been analysed. Theoretical results show that the RUADRC promises a timelier and more accurate positioning. Experimental results still confirm the advantages of the RUADRC over the LADRC on both reference tracking speed, accuracy and disturbance rejection ability.

Memory related predictive compensation control of Piezoelectric actuators based on global linearization Koopman theory

Piezoelectric actuators (PEAs) are widely applied in precision positioning. However, the nonlinear characteristics such as hysteresis and creep limit the ultra-precision applications. This paper proposes a linear model predictive control (MPC) scheme for compensating the nonlinearity of PEA. Firstly, a global linearization predictor is constructed based on Koopman theory to represent the hysteresis behavior of PEA. The high-precision predictor is implemented by a novel memory related neural network (NN), and the prediction error reaches only 0.002 μm. Then the tracking control problem is transformed into a linear MPC optimization problem, thereby avoids the sophisticated nonconvex optimization problem. In practice, the constrained MPC problem is rewritten into a dense form, and solved by quadratic programming technique. Finally, the validity of the proposed scheme is demonstrated by experiments. The short-term steady-state error of the proposed scheme is 0.002 μm, which is far less than that of the inversion method; the long-term steady-state performance also indicates its effectiveness in compensating creep. Further, the excellent frequency-dependent results show that the proposed scheme is superior to the existing control method. Especially, the computational efficiency can be improved by 20%. The proposed predictor and control method are of great significance for the tracking control of PEA.

Generation of subharmonics in acoustic resonators containing bubbly liquids: A numerical study of the excitation threshold and hysteretic behavior

In this paper we study the generation and behavior of subharmonics in a bubbly liquid confined in an acoustic resonator, through numerical simulations carried out at finite-amplitude acoustic pressure. Several configurations in terms of resonator length and driving frequency are considered here. Our results show that these frequency components, created from a higher-frequency signal at the source (ultrasound), are due to the nonlinearity of the medium at high acoustic-pressure amplitude and to the configuration of the resonator (geometry and boundaries). We also show that they have an amplitude-threshold dependence, which is in concordance with the literature. The response of these subharmonics to different sequences of pressure amplitudes also reveals the hysteretic nature of the bubbly liquid.

Dynamics of SIR model with heterogeneous response to intervention policy

In classical epidemic theory, behavior is assumed to be stationary. In recent years, epidemic models have been extended to include behaviors that transition in response to the current state of the epidemic. However, it is widely known that human behavior can exhibit strong history-dependence as a consequence of learned experiences. This history-dependence is similar to hysteresis phenomena that have been well-studied in control theory. To illustrate the importance of history-dependence for epidemic theory, we study dynamics of a variant of the SIRS model where individuals exhibit lazy-switch responses to prevalence dynamics, based on the Preisach hysteresis operator. The resulting model can possess a continuum of endemic equilibrium states characterized by different proportions of susceptible, infected and recovered populations. We consider how the limit point of the epidemic trajectory and the infection peak along this trajectory depend on the degree of heterogeneity of the response. Our approach supports the argument that public health responses during the emergence of a new disease can have fundamental long-term consequences for subsequent management efforts.

Novel predictors related to hysteresis and baseflow improve predictions of watershed nutrient loads: An example from Ontario's lower Great Lakes basin

Eutrophication has re-emerged in the lower Great Lakes basin resulting in critical water quality issues. Models that accurately predict nutrient loading from streams are needed to inform appropriate nutrient management decisions. Generalized additive models (GAMs) that use surrogate data from sensors to predict nutrient loads offer an alternative to commonly applied linear regression and may better handle relationship non-linearities and skewed water quality data. Five years (2015-2020) of water quantity and quality data from 11 agricultural watersheds in southern Ontario were used to develop GAMs to predict total phosphorus (TP) and nitrate (NO₃^-) loads. This study aimed to 1) use GAMs to predict nutrient loads using both common and novel predictors and 2) quantify and examine the variability in seasonal and annual nutrient loads. Along with routine surrogate model predictors (i.e., flow, turbidity, and seasonality), the addition of the baseflow proportion and the hydrograph position of flow observations improved model performance. Conversely, including the antecedent precipitation index minimally affected model performance, regardless of constituent. Seasonal and annual patterns in TP and NO₃^- load predictions mirrored that of the hydrologic regime. This study showed that parsimonious GAMs featuring novel model predictors can be used to predict nutrient loads while accounting for the partitioning of surface and subsurface flow paths and hysteresis between streamflow and water quality parameters that are frequently observed in a wide range of environments.

Hysteresis and fiscal stimulus in a recession

The COVID-19 pandemic initiated a deep global recession, and with interest rates at very low levels, warrants consideration of the efficacy of different forms of fiscal stimulus in response. History reveals that deep recessions may cause output and total factor productivity (TFP) hysteresis, a permanent or highly persistent fall in the levels of output and TFP relative to pre-recession trends. This article analyses the output and welfare multipliers of fiscal stimulus during a recession using a macro model with TFP and output hysteresis. We find that transfer payments, public consumption and investment all have high output and welfare multipliers due to their positive effects on TFP in a recessionary environment. However, public investment has the highest output and welfare multipliers, because it has a more positive impact on labour productivity due to the increase in the public capital stock.

Water adsorption characteristic and its impact on pore structure and methane adsorption of various rank coals

Coalbed methane not only is a new clean energy source, but also has potential damage to ecological environment. Water and methane coexist in coal reservoir; understanding the adsorption of water on coal and its impact on pore structure and methane adsorption of coal is vital to evaluate the reserves and productivity of coalbed methane. In the paper, water adsorption characteristics of various rank coals are firstly investigated by ten mathematical models. The modified Dent model provides a best fit, followed by GAB and Dent models. For GAB model, the primary site adsorption is more difficult to reach saturation, and the contribution rate of the secondary site adsorption is surprisingly high at P/P₀ approaching 0, which can be attributed to the possible overestimation of GAB monolayer adsorption capacity and secondary site adsorption. Besides, the low-rank coal sample YZG2 exhibits more prominent hysteresis than middle- to high-rank coals. The low-pressure hysteresis can be attributed to the water-water interactions over the primary site and the strengthened binding forces of water molecules in the water desorption process. In contrast, the high-pressure hysteresis largely depends on pore structure of coal such as ink-bottle pores, especially for the studied sample YZG2. Besides, pore analyses by low-temperature nitrogen adsorption method show that the pre-adsorbed water has remarkable influence on micropores smaller than 10 nm, and the micropores smaller than 4 nm almost disappear for water-equilibrated coals, which is closely related to the formed water clusters and capillary water in pore throats. This finding reveals that more methane gas can only be adsorbed in the larger pores of moist coal, and provides an explanation for water weakening methane adsorption capacity.

Mechanisms of energy dissipation and relationship with tissue composition in human meniscus

OBJECTIVE

The human meniscus is essential in maintaining proper knee joint function. The meniscus absorbs shock, distributes loads, and stabilizes the knee joint to prevent the onset of osteoarthritis. The extent of its shock-absorbing role can be estimated by measuring the energy dissipated by the meniscus during cyclic mechanical loading.

METHODS

Samples were prepared from the central and horn regions of medial and lateral human menisci from 8 donors (both knees for total of 16 samples). Cyclic compression tests at several compression strains and frequencies yielded the energy dissipated per tissue volume. A GEE regression model was used to investigate the effects of compression, meniscal side and region, and water content on energy dissipation in order to account for repeated measures within samples.

RESULTS

Energy dissipation by the meniscus increased with compressive strain from ∼0.1 kJ/m³ (at 10% strain) to ∼10 kJ/m³ (at 20% strain) and decreased with loading frequency. Samples from the anterior region provided the largest energy dissipation when compared to central and posterior samples (P < 0.05). Water content for the 16 meniscal tissues was 77.9 (C.I. 72.0-83.8%) of the total tissue mass. A negative correlation was found between energy dissipation and water content (P < 0.05).

CONCLUSION

The extent of energy dissipated by the meniscus is inversely related to loading frequency and meniscal water content.

Thermal hysteresis in microtubule assembly/disassembly dynamics: The aging-induced degradation of tubulin dimers

The assembly/disassembly of biological macromolecules plays an important role in their biological functionalities. Although the dynamics of tubulin polymers and their super-assembly into microtubule structures is critical for many cellular processes, details of their cyclical polymerization/depolymerization are not fully understood. Here, we use a specially designed light scattering technique to continuously examine the effects of temperature cycling on the process of microtubule assembly/disassembly. We observe a thermal hysteresis loop during tubulin assembly/disassembly, consistently with earlier reports on the coexistence of tubulin and microtubules as a phase transition. In a cyclical process, the structural hysteresis has a kinetic component that depends on the rate of temperature change but also an intrinsic thermodynamic component that depends on the protein topology, possibly related to irreversible processes. Analyzing the evolution of such thermal hysteresis loops over successive cycles, we found that the assembly/disassembly ceases after some time, which is indicative of protein aging leading to its inability to self-assemble after a finite number of temperature cycles. The emergence of assembly-incompetent tubulin could have major consequences for human pathologies related to microtubules, including aging, neurodegenerative diseases and cancer.

Statics of plant mechanics

David A. Robinson took all that was known in his time about ocular anatomy, extraocular muscle force generation, and neural control of extraocular muscles, and integrated this information into a quantitative model of the static behavior of the ocular motor plant suitable for application to strabismus, the pathological misalignment of the eyes. Robinson's comprehensive mathematical descriptions of the essential details he knew to be the properties of the ocular motor plant highlighted the critical gaps in the state of knowledge that he very explicitly bridged by quantitative assumptions that later motivated focused research that ultimately revealed many missing pieces of the puzzle. Robinson suggested that it should be possible, in principle, to account (in a computational model) for all the mechanical factors and neural drives that regulate binocular alignment and strabismus, and that such modeling could assist in diagnosis and treatment of this common ophthalmic disorder.

Calculated versus measured iron losses and instantaneous magnetization power functions of electrical steel

Magnetic energy loss P of soft magnetic laminations like SiFe sheets tends to be expressed through an integral over the power product H · dB/dt. Already in earlier papers, we stressed that distinctions are needed for the quantities H and B. However, they are not considered in practically consistent ways, in the so far literature. Here, we discuss these distinctions in closer ways, comparing loss determination by calculation and measurement, respectively. A physically consistent procedure is described for the determination of loss and magnetization power functions through measurement of bi-located quantities H _S and B _C (S surface, C cross section). On the other hand, it is concluded that corresponding quantitative calculations-based on co-located quantities H and B-are impeded by the high amount of technological parameters of modern steel products. For example, they result from chemical additions, and-in particular-also from specific technologies of rolling, annealing, coating or scribing.

Quasi-linear viscoelastic behavior of fresh porcine ureter

PURPOSE

To evaluate the viscoelastic properties of the fresh porcine ureter. Prove the QLV theory can sufficiently model the stress relaxation function of porcine ureters, and determine the QLV model constants which may provide insight into the synthesis of ureteral scaffolds with biomimetic viscoelastic properties in tissue engineering.

METHODS

Hysteresis tests were applied to study the differences in dissipated energy ratio for each different strain group. In stress relaxation tests, samples were sub-grouped and quickly ramping up to 5%, 20%, and 30% strain in each group and gradually relaxed to a corresponding level. Bringing together the quasi-linear viscoelasticity (QLV) theory and stress relaxation function to determine the eight constants of the ureteral tissue, and fitting the raw data with the model via MATLAB.

RESULTS

The hysteresis response measurement results revealed that the porcine ureter was a highly dissipative material and there were differences between toe and linear region in stress-stain curve. The stress relaxation results revealed ureters responded with time-dependent decay of stress. The eight constants of the ureteral QLV model were determined for three different strain groups, and we proved that the QLV model can sufficiently adapt the experimental data of the ureter stress relaxation.

CONCLUSION

This study investigated the time-dependent properties of the porcine ureter, and demonstrated the QLV theory could be used to evaluate the viscoelastic properties of the porcine ureteral tissue.

Influence of release rate, dose and co-administration on pharmacokinetics, pharmacodynamics and PK-PD relationship of tanshinone IIA and tanshinol

The present study aims to investigate the influence of release rate, dose and co-administration on pharmacokinetics (PK) and pharmacodynamics (PD) of tanshinone IIA (TA) and tanshinol (TS), and reveal the changes in their PK-PD relationships. Sustained and immediate release pellets of TS and TA were prepared respectively, and oral administrated to angina model rabbits according to the experimental design. The administration dose of TS was 50, 35 or 20 mg/kg and that of TA was 30 mg/kg. Then, plasma concentrations of TS and TA were measured to evaluate the pharmacokinetics. Pharmacodynamic biomarkers including cardiac troponin (cTn-I), creatine kinase (CK-MB), superoxide dismutase (SOD) and nitric oxide (NO) were measured to evaluated the effects of cardioprotection, amelioration of oxidative stress and vasorelaxation of TS and TA. Parameters such as maximum plasma concentration (C_max), maximum effect (E_max), time to C_max or E_max (TC_max or TE_max), areas under the plasma concentration or effect curves (AUC_0-∞ or AUEC) and pharmacodynamic efficiency (EFF) were calculated based on non-compartmental analysis. Beside, PK-PD relationship/hysteresis was evaluated. The TE_max was less sensitive than TC_max to changes in release rate. The E_max, AUEC and EFF showed increasing trend as the decrease of release rate even that the AUC_0-∞ showed no significant difference. In addition, slow drug release decreased the magnitude of hysteresis of TS and TA. The sensitivities of E_max and AUEC of four biomarkers to changes in dose were varied and relatively lower than those of C_max and AUC_0-∞. The EFF decreased and the magnitude of hysteresis increased for high dose. The C_max and AUC_0-∞ of TS and TA showed little difference after co-administration. The E_max and AUEC of four biomarkers increased for immediate release pellets (P < 0.05 or P < 0.01) and generally decreased for sustained release pellets (P < 0.05 or P < 0.01) after co-administration. In addition, the magnitudes of hysteresis of four biomarkers decreased for immediate release pellets and generally increased for sustained release pellets after co-administration. In summary, the dissociated and unstable PK-PD relationship should be considered during optimization of dosage forms and regimens to make sure the rationality, safety and efficacy. These findings could also provide some valuable information for the development and clinical therapy of other drugs.

Diel and seasonal patterns of soil CO2 efflux in a temperate tidal marsh

Tidal marshes store large amounts of carbon; however, little is known about the patterns, magnitudes, and biophysical drivers that regulate CO₂ efflux from these ecosystems. Due to harsh environmental conditions (e.g., flooding), it is difficult to measure continuous soil CO₂ efflux in tidal marshes. These data are necessary to inform empirical and process-based models and to better quantify carbon budgets. We performed automated (30 min) and manual (bi-monthly) soil CO₂ efflux measurements, for ~20 months, at two sites in a temperate tidal marsh: tall Spartina (TS; dominated by S. cynosuroides) and short Spartina (SS; dominated by S. alterniflora). These measurements were coupled with water quality, canopy spectral reflectance, and meteorological measurements. There were no consistent diel patterns of soil CO₂ efflux, suggesting a decoupling of soil CO₂ efflux with diel variations in temperature and tides (i.e., water level) showing a hysteresis effect. Mean soil CO₂ efflux was significantly higher at SS (2.15 ± 1.60 μmol CO₂ m^-2 s^-1) than at TS (0.55 ± 0.80 μmol CO₂ m^-2 s^-1), highlighting distinct biogeochemical spatial variability. At the annual scale, air temperature explained >50% of the variability in soil CO₂ efflux at both sites; and water level and salinity were secondary drivers of soil CO₂ efflux at SS and TS, respectively. Annual soil CO₂ efflux varied from 287-876 to 153-211 g C m^-2 y^-1 at SS and TS, respectively, but manual measurements underestimated the annual flux by <67% at SS and <23% at TS. These results suggest that measuring and modeling diel soil CO₂ efflux variability in tidal marshes may be more challenging than previously expected and highlight large discrepancies between manual and automated soil CO₂ efflux measurements. New technical approaches are needed to implement long-term automated measurements of soil CO₂ efflux across wetlands to properly estimate the carbon balance of these ecosystems.

Hysteretic device characteristics indicate cardiac contractile state for guiding mechanical circulatory support device use

Background

Acute heart failure and cardiogenic shock remain highly morbid conditions despite prompt medical therapy in critical care settings. Mechanical circulatory support (MCS) is a promising therapy for these patients, yet remains managed with open-loop control. Continuous measure of cardiac function would support and optimize MCS deployment and weaning. The nature of indwelling MCS provides a platform for attaining this information. This study investigates how hysteresis modeling derived from MCS device signals can be used to assess contractility changes to provide continuous indication of changing cardiac state. Load-dependent MCS devices vary their operation with cardiac state to yield a device–heart hysteretic interaction. Predicting and examining this hysteric relation provides insight into cardiac state and can be separated by cardiac cycle phases. Here, we demonstrate this by predicting hysteresis and using the systolic portion of the hysteresis loop to estimate changes in native contractility. This study quantified this measurement as the enclosed area of the systolic portion of the hysteresis loop and correlated it with other widely accepted contractility metrics in animal studies (n = 4) using acute interventions that alter inotropy, including a heart failure model. Clinical validation was performed in patients (n = 8) undergoing Impella support.

Results

Hysteresis is well estimated from device signals alone (r = 0.92, limits of agreement: − 0.18 to 0.18). Quantified systolic area was well correlated in animal studies with end-systolic pressure–volume relationship (r = 0.84), preload recruitable stroke work index (r = 0.77), and maximum slope of left ventricular pressure (dP/dt_max) (r = 0.95) across a range of inotropic conditions. Comparable results were seen in patients with dP/dt_max (r = 0.88). Diagnostic capability from ROC analysis yielded AUC measurements of 0.92 and 0.90 in animal and patients, respectively.

Conclusions

Mechanical circulatory support hysteretic behavior can be well modeled using device signals and used to estimate contractility changes. Contractility estimate is correlated with other accepted metrics, captures temporal trends that elucidate changing cardiac state, and is able to accurately indicate changes in inotropy. Inherently available during MCS deployment, this measure will guide titration and inform need for further intervention.

Chiral separation of oxazolidinone analogues by liquid chromatography on polysaccharide stationary phases using polar organic mode

The enantioseparation of four oxazolidinone and one biosimilar thiazolidine derivatives was performed on seven different polysaccharide-type chiral stationary phases (Lux Amylose-1, Lux i-Amylose-1, Lux Amylose-2, Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4) differing in backbone (cellulose or amylose), substituent or the immobilization technologies (coated or immobilized). Polar organic mode was employed using neat methanol (MeOH), ethanol (EtOH), 2-propanol (IPA) and acetonitrile (ACN) either alone or in combinations as mobile phases. Amylose-based columns with ACN provided the highest enantioselectivities for the studied compounds. The replacement of an oxygen with a sulfur atom in the backbone of the studied analytes significantly alters the enantiomer recognition mechanism. Chiral selector-, mobile-phase-, and interestingly immobilization-dependent enantiomer elution order reversal was also observed. Reversal of elution order and hysteresis of retention and enantioselectivity was further investigated using different mixtures of IPA:MeOH and ACN:MeOH on amylose-type chiral stationary phases. Hysteresis of retention and enantioselectivity was observed on all investigated amylose-type columns and binary eluent mixtures, which can be further utilized for fine-tuning chiral separation performance of the studied columns.

Reproducibility and diurnal variation of the directional sensitivity of the cerebral pressure-flow relationship in men and women

The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAv_T/∆MAP_T) and posterior cerebral arteries (PCA; ∆PCAv_T/∆MAP_T); 2) sex differences. ∆MCAv_T/∆MAP_T and ∆PCAv_T/∆MAP_T were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAv_T/%MAP_T, %PCAv_T/%MAP_T). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAv_T/∆MAP_T (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAv_T/%MAP_T (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAv_T/∆MAP_T (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.

Combining sediment fingerprinting and hydro-sedimentary monitoring to assess suspended sediment provenance in a mid-mountainous Mediterranean catchment

Soil erosion and sediment transport are controlled by complex factors promoting variable responses in catchment's erosion rates and sediment yields. To mitigate eventual negative effects derived from altered fluxes, integrated catchment management plans should assess the sediment cascade from upstream erosive processes, sediment mobilization through hillslopes and within the channel, up to downstream sediment yields. This study links hydro-sedimentary dynamics with sediment fingerprinting source ascription in a mid-mountainous Mediterranean catchment during five hydrological years (2013-2018). Soil colour parameters and fallout radionuclides were used as tracers to predict dominant suspended sediment sources using (i) a Bayesian mixing model (MixSIAR) and (ii) an End Member Mixing Analysis (EMMA). MixSIAR suggested that crops were the dominant source in most of the collected samples. EMMA showed similar results, clustering all except one sediment samples close to the crop and channel bank signatures. In addition, a quantitative hysteresis index was calculated and floods were clustered in function of their hydro-sedimentary characteristics. Despite different patterns were associated to each of the four identified clusters (e.g. different sediment loads and maximum suspended sediment concentrations), correlation between sediment origin and hydro-sedimentary variables was not significant due to the little seasonal variation in source type ascription.

Pharmacokinetic and pharmacodynamic assessment of histamine H3 receptor occupancy by enerisant: a human PET study with a novel H3 binding ligand, [11C]TASP457

PURPOSE

Histamine H₃ receptor antagonists and inverse agonists have been extensively developed to treat sleep-wake, neurocognitive, and allied disorders. However, potential adverse effects, including insomnia, hampered the clinical use of these drugs, possibly due to their persistent interaction with the target molecules. The purpose of the present study was to estimate the pharmacokinetics and pharmacodynamics of enerisant, a novel antagonist and inverse agonist for histamine H₃ receptors.

METHODS

To measure the histamine H₃ receptor occupancy by enerisant, positron emission tomography studies using [¹¹C]TASP457, a specific radioligand for histamine H₃ receptors, were performed in 12 healthy men at baseline and at 2 h after oral administration of enerisant hydrochloride. For three of these subjects, two additional scans were performed at 6 and 26 h after the administration. Relationships between the receptor occupancy by enerisant and its dose and plasma concentrations were then analyzed.

RESULTS

Administration of enerisant hydrochloride decreased the radioligand binding in a dose-dependent manner. The estimated receptor occupancy values at 2 h varied as a function of its dose or plasma concentration. The time course of the occupancy showed persistently high levels (> 85%) in the two subjects with higher doses (25 and 12.5 mg). The occupancy was also initially high at 2 h and 6 h with the lower dose of 5 mg, but it decreased to 69.7% at 26 h.

CONCLUSION

The target engagement of enerisant was demonstrated in the brains of living human subjects. The occupancy of histamine H₃ receptors by enerisant at 2 h can be predicted by applying the plasma concentration of enerisant to Hill's plot. The preliminary time-course investigation showed persistently high brain occupancy with high doses of enerisant despite the decreasing plasma concentration of the drug. Five milligrams or less dose would be appropriate for the treatment for narcolepsy with initially high occupancy allowing for effective treatment of narcolepsy, and then the occupancy level would be expected to decrease to a level to avoid this drug's unwanted side effect of insomnia at night, although further research is warranted to confirm the statement since the expected decrease is based on the finding in one subject.

TRIAL REGISTRATION

This study was retrospectively registered with ClinicalTrials.gov (NCT04631276) on November 17, 2020.

Phase leading active disturbance rejection control for a nanopositioning stage

Hysteresis severely reduces positioning accuracy of a piezoelectric nanopositioning system. Inverse hysteresis model-based control is difficult to maintain satisfied performance in presence of uncertainties and disturbances. Linear active disturbance rejection control (LADRC) is a practical approach. However, phase lag of the total disturbance estimation degrades its estimation ability and tracking performance. In this work, a phase-leading extended state observer (PLESO) is constructed by adding a phase-leading network to a linear extended state observer. Advantage of the PLESO on estimating the time-varying total disturbance is analyzed, and influence of the multiplication factor introduced by a PLESO is also discussed. By a leading phase provided by the PLESO, the phase-leading active disturbance rejection control (PLADRC) can compensate the total disturbance timelier, and more satisfied positioning can be guaranteed. Experimental results show that the PLADRC is superior to the LADRC in terms of dynamic responses and disturbance rejection. Without introducing nonlinearities or increasing the order, the PLESO provides an effective way to enhance the active disturbance rejection control (ADRC).

Early warning signals from the periphery: A model suggestion for the study of critical transitions

Studies on the possibility of predicting critical transitions with statistical methods known as early warning signals (EWS) are often conducted on data generated with equation-based models (EBMs). These models base on difference or differential equations, which aggregate a system's components in a mathematical term and therefore do not allow for a detailed analysis of interactions on micro-level. As an alternative, we suggest a simple, but highly flexible agent-based model (ABM), which, when applying EWS-analysis, gives reason to (a) consider social interaction, in particular negative feedback effects, as an essential trigger of critical transitions, and (b) to differentiate social interactions, for example in network representations, into a core and a periphery of agents and focus attention on the periphery. Results are tested against time series from a networked version of the Ising-model, which is often used as example for generating hysteretic critical transitions.

How environmental stress leads to alternative microbiota states in a river ecosystem: A new insight into river restoration

Catastrophic shifts in river ecosystems can abruptly degrade their structures and functions, often reducing the efficacy of traditional remediation targeting physicochemical properties. Alternative stable states theory can not only explain this phenomenon but also provide a new insight into river restoration; however, little is known about the existence and implications of alternative stable states in a river. Considering the important role of benthic microbiota in sustaining river ecosystem structures and functions, ecological theory and high-throughput sequencing were combined to firstly investigate multi-stability in microbial communities and its relationship with environmental factors in river sediments. The Nanjing reach of the Yangtze River was selected as the study area because of its huge spatial heterogeneity and varying degrees of pollution. Bimodal distributions combined with temporal variations of microbiota status provided direct evidence of bistability by showing the instability at the intermediate. In addition, environmental stress, particularly concentrations of NH₄⁺-N and NO₃^--N, was identified as an important driver of alternative microbiota states from the perspectives of the behavior of bistable ecosystems. Comparison of α-diversity indices and network properties between two alternative microbiota states revealed that the diversity and co-occurrence pattern of microbial communities will be high if they are settled in favorable environments (i.e., comprehensive sediment quality identification index > 3.7). Key taxa, including Clostridiales, Nitrospirales and Myxococcales, were discerned by combining LEfSe and network analysis, and their strong interspecies interactions were believed to be an important factor in triggering alternative microbiota states. This study suggests alternative stable states theory should be considered in river remediation to better understand the response of river ecosystems to environmental stress and the effect of hysteresis, benefiting the implementation of effective monitoring and restoration strategies in a river of urban area.

The interaction of anti-DNA antibodies with DNA antigen: Evidence for hysteresis for high avidity binding

Antibodies to DNA (anti-DNA) are the serological hallmark of systemic lupus erythematosus. Previous studies have indicated that the phosphodiester backbone is the main antigenic target, with electrostatic interactions important for high avidity. To define further these interactions, the effects of ionic strength on anti-DNA binding of SLE plasmas were assessed in association and dissociation assays by ELISA. As these studies demonstrated, increasing ionic strength to a concentration of 1000 mM NaCl reduced antibody binding although the extent of the reduction varied among samples. In dissociation assays, differences among plasmas were also observed. For one of the plasmas, binding to DNA displayed resistance to dissociation by increasing ionic strength even though these concentrations limited binding in association assays. Time course studies showed a gradual change in binding interactions. These studies indicate that anti-DNA binding can involve both electrostatic and non-electrostatic interactions, with binding in some plasmas showing evidence of hysteresis.

Ventricular tachyarrhythmia after single chamber pacemaker programming - what is the mechanism?

Pacemaker can be life-saving in high grade atrioventricular (AV) blocks. But this reality is occasionally challenged by arrhythmias induced by ventricular pacing. Some of the events are related to automated pacemaker algorithms. Managed ventricular pacing (MVP) is one such example which has delivered benefits but has also been associated with ventricular tachyarrhythmias (VT). Our case is possibly the first report of hysteresis induced symptomatic VT.

Overcoming an "irreversible" threshold: A 15-year fire experiment

A key pursuit in contemporary ecology is to differentiate regime shifts that are truly irreversible from those that are hysteretic. Many ecological regime shifts have been labeled as irreversible without exploring the full range of variability in stabilizing feedbacks that have the potential to drive an ecological regime shift back towards a desirable ecological regime. Removing fire from grasslands can drive a regime shift to juniper woodlands that cannot be reversed using typical fire frequency and intensity thresholds, and has thus been considered irreversible. This study uses a unique, long-term experimental fire landscape co-dominated by grassland and closed-canopy juniper woodland to determine whether extreme fire can shift a juniper woodland regime back to grassland dominance using aboveground herbaceous biomass as an indicator of regime identity. We use a space-for-time substitute to quantify herbaceous biomass following extreme fire in juniper woodland up to 15 years post-fire and compare these with (i) 15 years of adjacent grassland recovery post-fire, (ii) unburned closed-canopy juniper woodland reference sites and (iii) unburned grassland reference sites. Our results show grassland dominance rapidly emerges following fires that operate above typical fire intensity thresholds, indicating that grassland-juniper woodlands regimes are hysteretic rather than irreversible. One year following fire, total herbaceous biomass in burned juniper stands was comparable to grasslands sites, having increased from 5 ± 3 g m^-2 to 142 ± 42 g m^-2 (+2785 ± 812 percent). Herbaceous dominance in juniper stands continued to persist 15-years after initial treatment, reaching a maximum of 337 ± 42 g m^-2 eight years post-fire. In juniper encroached grasslands, fires that operate above typical fire intensity thresholds can provide an effective method to reverse juniper woodland regime shifts. This has major implications for regions where juniper encroachment threatens rancher-based economies and grassland biodiversity and provides an example of how to operationalize resilience theory to disentangle irreversible thresholds from hysteretic system behavior.