Conductance Responses Research Articles

Investigation on thermal conductivities of plain-woven carbon/phenolic and silica/phenolic composites at high temperature: Theoretical prediction and experiment

Phenolic resin-based ablation materials have found widespread applications in the aerospace industry. The prediction of their thermal conductivity is of paramount importance for the optimization and evaluation for thermal protection systems. However, there is rarely reported thermal conductivity performance of phenolic composites during ablation processes. Therefore, this investigation theoretically predicts the dynamic response of thermal conductivity at high temperatures for plain-woven carbon/phenolic and high silica/phenolic composites. By combining the progressive cubic ablation model with existing composite material property formulas, a multiscale prediction model for effective thermal conductivity is developed. The thermal performance of the resin matrix, reinforcing fibers, yarns, and overall fabric composites is calculated. Additionally, mesoscale representative volume elements are implemented to investigate the overall heat transfer characteristics of carbon/phenolic and high-silica/phenolic composites, including temperature and heat flux distributions. Moreover, both composites thermal conductivities are measured in the range from 298 K to 473 K. The proposed prediction model demonstrates good reliability, with average deviations of 3.76 % and 7.36 % compared to finite element analysis results and experimental data, respectively.

Biochemical versus stomatal acclimation of dynamic photosynthetic gas exchange to elevated CO2 in three horticultural species with contrasting stomatal morphology.

Understanding photosynthetic acclimation to elevated CO2 (eCO2) is important for predicting plant physiology and optimizing management decisions under global climate change, but is underexplored in important horticultural crops. We grew three crops differing in stomatal density-namely chrysanthemum, tomato, and cucumber-at near-ambient CO2 (450 μmol mol-1) and eCO2 (900 μmol mol-1) for 6 weeks. Steady-state and dynamic photosynthetic and stomatal conductance (gs) responses were quantified by gas exchange measurements. Opening and closure of individual stomata were imaged in situ, using a novel custom-made microscope. The three crop species acclimated to eCO2 with very different strategies: Cucumber (with the highest stomatal density) acclimated to eCO2 mostly via dynamic gs responses, whereas chrysanthemum (with the lowest stomatal density) acclimated to eCO2 mostly via photosynthetic biochemistry. Tomato exhibited acclimation in both photosynthesis and gs kinetics. eCO2 acclimation in individual stomatal pore movement increased rates of pore aperture changes in chrysanthemum, but such acclimation responses resulted in no changes in gs responses. Although eCO2 acclimation occurred in all three crops, photosynthesis under fluctuating irradiance was hardly affected. Our study stresses the importance of quantifying eCO2 acclimatory responses at different integration levels to understand photosynthetic performance under future eCO2 environments.

Suffering more in imagination than in reality? Mental imagery and fear generalization

Mental imagery may represent a weaker form of perception and, thus, mental images may be more ambiguous than visual percepts. If correct, the acquisition of fear would be less specific for imagined fears in comparison to perceptual fears, perhaps facilitating broader fear generalization. To test this idea, a two-day differential fear conditioning experiment (N = 98) was conducted. On day one, two groups of participants underwent differential fear conditioning such that a specific Gabor patch orientation (CS+) was paired with mild shocks (US) while a second Gabor patch of orthogonal orientation (CS-) was never paired with shock. Critically, one group imagined the Gabor patches and the other group was visually presented the Gabor patches. Next, both groups were presented visual Gabor patches of similar orientations (GCS) to the CS+. On day two, to assess the persistence of imagined fear, participants returned to the lab and were tested on the GCS devoid of shock. For day one, in contrast to our primary hypothesis, both self-report and skin conductance response measures did not show a significant interaction between the GCS and groups. On day two, both measures demonstrated a persistence of imagined fear, without US delivery. Taken together, rather than demonstrating an overgeneralization effect, the results from this study suggest that imagery-based fear conditioning generalizes to a similar extent as perceptually acquired fear conditioning. Further, the persistence of imagery-based fear may have unique extinction qualities in comparison to perceptual-based fear.

Transport properties through alternating borophene and graphene superlattices

The electronic transport properties of two junctions (BGB, GBG) made of borophene (B) and graphene (G) are investigated. Using the transfer matrix method with Chebyshev polynomials, we have studied single and multiple barriers in a superlattice configuration. We showed that a single barrier exhibits remarkable tilted transport properties, with perfect transmission observed for both junctions under normal incidence. We found that robust superlattice transmission is maintained for multiple barriers, particularly in the BGB junction. It turns out that by varying the incident energy, many gaps appear in the transmission probability. The number, width, and position of these transmission gaps can be manipulated by adjusting the number of cells, incident angle, and barrier characteristics. For diffuse transport, we observed considerable variations in transmission probability, conductance and the Fano factor, highlighting the sensitivity of these junctions to the physical parameters. We showed different behaviors between BGB and GBG junctions, particularly with respect to the response of conductance and Fano factor when barrier height varies. For ballistic transport, we have seen that the minimum scaled conductance is related to the maximum Fano factor, demonstrating their control under specific conditions of the physical parameters. Analysis of the length ratio (geometric factor) revealed some remarkable patterns, where scaled conductance and the Fano factor converged to certain values as the ratio approached infinity.

Poly(vinyl pyridine) coatings cross-linked with transition metal complexes as active layers for biosensors sensitive to protein adsorption and cell adhesion

The possibility of application of poly(4-vinyl pyridine) layers cross-linked with transition metal complexes as active layers in biomedical sensors was tested. The successful modification of the P4VP coating with CuBr2 or ZnBr2 was verified using time of flight - secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The topography and wettability of the coatings were examined by using atomic force microscopy and water contact angles measurements, respectively. Tests of biological activity of coatings indicated strong protein adsorption, good biocompatibility, and no antimicrobial activity. The potential of the coatings to be used as active layers of biosensors was verified, by systematic impedance-based measurements, which showed the sensitivity of the P4VP:CuBr2 coatings to the presence of proteins and cells in different concentrations. The high selectivity of the coatings toward the defined analyte was confirmed by the specific antigen–antibody immunoreaction, and the possibility of in situ monitoring of protein adsorption and cell adhesion also for individual cells was presented. Finally, the conductive response of a bilayer system that mimics Organic Field Effect Transistor was shown. These results point to a great potential for both coatings to serve as active layers of sensitive and highly selective biosensors.

The Effect of Biological Secondary Treated Domestic Wastewater on Agronomic Properties and Element Content of Some Forage Plants

Aims: This study was carried out to determine the effect of domestic advanced biological treated domestik wastewater on the agronomic properties and nutritional content of some forage crops, as a result of the increasing interest in the use of treated wastewater in agriculture. Material and methods: Biologically treated domestic wastewater was diluted with 25%, 50% and 75% pure water and applied to crested wheatgrass (Agropyron cristatum Geartn), orchard grass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) pots according to field capacity. Results: Alfalfa, orchard grass and crested wheatgrass plants were used as trial plants. The effect of the diluted wastewater application on the height of crested wheatgrass, orchard grass and alfalfa was significant. From the first mow, alfalfa and orchard grass had increased green and dry weights per pot, with the most marked increase for alfalfa. The wastewater ratios caused an increase in nutrient and metal concentrations in the three plants, while a decrease in the Se concentration in alfalfa and crested wheatgrass. Diluted wastewater not effected alfalfa Ca concentration significantly. While the dilute wastewater significantly and positively effected the relationship of orchard grass with all elements, but Se affected negatively. Soil organic matter and electrical conductivity increased and pH decreased with increasing wastewater ratio. Discussion: Diluted domestic water application played an important role in nutrient and metal concentrations by mediating increased plant element uptake associated with soil organic matter and electrical conductivity responses. Conclusions: However, long-term field studies are required to determine the dilution rate at which the salinity risk threshold can be determined.

The impact of the left inferior frontal gyrus on fear extinction: A transcranial direct current stimulation study

IntroductionFear extinction is a fundamental component of exposure-based therapies for anxiety-related disorders. The renewal of fear in a different context after extinction highlights the importance of contextual factors. In this study, we aimed to investigate the causal role of the left inferior frontal gyrus (LiFG) in the context-dependency of fear extinction learning via administration of transcranial direct current stimulation (tDCS) over this area. Methods180 healthy subjects were assigned to 9 groups: 3 tDCS conditions (anodal, cathodal, and sham) × 3 context combinations (AAA, ABA, and ABB). The fear conditioning/extinction task was conducted over three consecutive days: acquisition, extinction learning, and extinction recall. tDCS (2 mA, 10min) was administered during the extinction learning phase over the LiFG via a 4-electrode montage. Skin conductance response (SCR) data and self-report assessments were collected. ResultsDuring the extinction learning phase, groups with excitability-enhancing anodal tDCS showed a significantly higher fear response to the threat cues compared to cathodal and sham stimulation conditions, irrespective of contextual factors. This effect was stable until the extinction recall phase. Additionally, excitability-reducing cathodal tDCS caused a significant decrease of the response difference between the threat and safety cues during the extinction recall phase. The self-report assessments showed no significant differences between the conditions throughout the experiment. ConclusionIndependent of the context, excitability enhancement of the LiFG did impair fear extinction, and led to preservation of fear memory. In contrast, excitability reduction of this area enhanced fear extinction retention. These findings imply that the LiFG plays a role in the fear extinction network, which seems to be however context-independent.

Observers predict actions from facial emotional expressions during real-time social interactions

In face-to-face social interactions, emotional expressions provide insights into the mental state of an interactive partner. This information can be crucial to infer action intentions and react towards another person’s actions. Here we investigate how facial emotional expressions impact subjective experience and physiological and behavioral responses to social actions during real-time interactions. Thirty-two participants interacted with virtual agents while fully immersed in Virtual Reality. Agents displayed an angry or happy facial expression before they directed an appetitive (fist bump) or aversive (punch) social action towards the participant. Participants responded to these actions, either by reciprocating the fist bump or by defending the punch. For all interactions, subjective experience was measured using ratings. In addition, physiological responses (electrodermal activity, electrocardiogram) and participants’ response times were recorded. Aversive actions were judged to be more arousing and less pleasant relative to appetitive actions. In addition, angry expressions increased heart rate relative to happy expressions. Crucially, interaction effects between facial emotional expression and action were observed. Angry expressions reduced pleasantness stronger for appetitive compared to aversive actions. Furthermore, skin conductance responses to aversive actions were increased for happy compared to angry expressions and reaction times were faster to aversive compared to appetitive actions when agents showed an angry expression. These results indicate that observers used facial emotional expression to generate expectations for particular actions. Consequently, the present study demonstrates that observers integrate information from facial emotional expressions with actions during social interactions.

The impact of helium clusters on the electronic thermal transport properties of tungsten plasma-facing materials at finite temperatures

In this work, we investigated the impact of different concentrations of helium (He) impurities on the electronic thermal transport properties of tungsten plasma-facing materials (W-PFMs) at finite temperatures using the W-He tight-binding (TB) potential model. We found that the electronic transport performance decreases with increasing He atom concentration at different sites, where the greatest reduction in the electrical conductivity of the system is caused by the introduction of He atoms at neighboring tetrahedral sites. As the temperature increases, the electrical conductivity decreases, while the electronic thermal conductivity increases. Importantly, the higher the temperature is, the weaker the response of the electrical conductivity and electronic thermal conductivity to the He atom concentration. We suggest that this behavior is attributed to the diverse contributions of scattering mechanisms within various temperature ranges. Furthermore, as the temperature increases, the electron scattering mechanism gradually transitions from electron-impurity scattering to electron-electron scattering. Additionally, our calculated atomic resolved electrical conductivity data indicate that at lower temperatures, the electrical conductivity is predominantly contributed by W atoms around the He cluster.

Exploring driving anger-caused impairment of takeover performance among professional taxi drivers during partially automated driving

Partially automated systems are expected to reduce road crashes related to human error, even amongst professional drivers. Consequently, the applications of these systems into the taxi industry would potentially improve transportation safety. However, taxi drivers are prone to experiencing driving anger, which may subsequently affect their takeover performance. In this research, we explored how driving anger emotion affects taxi drivers’ driving performance in various takeover scenarios, namely Mandatory Automation-Initiated transition (MAIT), Mandatory Driver-Initiated transition (MDIT), and Optional Driver-Initiated transition (ODIT). Forty-seven taxi drivers participated in this 2·3 mixed design simulator experiment (between-subjects: anger vs. calmness; within-subjects: MAIT vs. MDIT vs. ODIT). Compared to calmness, driving anger emotion led to a narrower field of attention (e.g., smaller standard deviations of horizontal fixation points position) and worse hazard perception (e.g., longer saccade latency, smaller amplitude of skin conductance responses), which resulted in longer takeover time and inferior vehicle control stability (e.g., higher standard deviations of lateral position) in MAIT and MDIT scenarios. Angry taxi drivers were more likely to deactivate vehicle automation and take over the vehicle in a more aggressive manner (e.g., higher maximal resulting acceleration, refusing to yield to other road users) in ODIT scenarios. The findings will contribute to addressing the safety concerns related to driving anger among professional taxi drivers and promote the widespread acceptance and integration of partially automated systems within the taxi industry.

Assessing physiological arousal and emotional valence during behavioral intervention for pediatric feeding difficulties: A pilot study

AbstractThis study's purpose is to introduce a new measurement system that objectively assesses the social validity of behavioral feeding intervention from the child's perspective via the concurrent measurement of two dimensions of emotion. To date, the primary measures of social validity for behavioral feeding intervention are caregiver treatment acceptability and satisfaction surveys. This is the first study to objectively measure two dimensions of emotion, physiological arousal and emotional valence, while children received behavioral intervention for feeding difficulties. Data collectors used a new open‐source data collection software, cometrics, developed to synchronize and record physiological and observational data. Physiological data was collected using a wearable biosensor and observers recorded an index of child happiness, unhappiness, or neither using definitions by Phipps et al. (2022) for six children with a pediatric feeding disorder. Two out of six children needed programmed habituation to the device before data collection. All children assented to wearing the device during data collection. Recorded indices mapped to separable physiological states using electrodermal activity and its constituent components, skin conductance responses and skin conductance level, in addition to skin temperature. Findings demonstrated the feasibility of measuring two dimensions of child emotions during behavioral feeding intervention and revealed that children's physiological responses were distinctly different during intervals scored as happy, unhappy, or neither. This new data collection system has implications for future research on the child's emotional experience of behavioral feeding treatment and increases the possibilities for improving clinical practice.

Secure attachment priming inhibits the generalization of conditioned fear

BackgroundFear overgeneralization constitutes a susceptibility factor contributing to the development and maintenance of anxiety spectrum disorders. Extant research has demonstrated that exposure to positive and supportive social relationships attenuates fear acquisition and promotes the extinction of conditioned fear responses. However, the literature lacks investigation into the effect of secure attachment priming on inhibiting the generalization of conditioned fear.MethodsIn this study, college students were recruited via online platforms to voluntarily engage in the experimental procedures, resulting in 57 subjects whose data were deemed suitable for analysis. The experimental protocol consisted of four consecutive phases: pre-acquisition, acquisition, priming, and generalization. The priming phase consisted of two experimental conditions: secure attachment priming (experimental group) and positive emotion priming (control group). This study adopted the perceptual discrimination fear conditioning paradigm, employing subjective expectancy of shock ratings and skin conductance responses as primary assessment indices. Individual difference variables were measured using corresponding psychological measurement scales.ResultsIn terms of generalization degree, a notable divergence surfaced in the skin conductance responses across various generalization materials between the secure attachment priming group and the control group. Similarly, during generalization extinction, a significant disparity emerged in the skin conductance responses across different generalization phases between the secure attachment priming group and the control group. In addition, individual differences analyses revealed that the inhibitory effect of secure attachment priming on fear generalization was not affected by intolerance of uncertainty and attachment orientations. Conversely, slope analyses confirmed that as intolerance of uncertainty increased, the inhibitory effect of positive emotion priming on fear generalization was attenuated.ConclusionThe findings suggest that activating participants' representations of secure attachment via imagination effectively attenuates the generalization of perceptual fear at the physiological level. The inhibitory effect of secure attachment priming appears to be distinct from positive emotional modulation and remains unaffected by individual trait attachment styles. These results offer novel insights and avenues for the prevention and clinical intervention of anxiety spectrum disorders.

Investigating grain and grain boundary effects on charge transport and dielectrics in BaCoxAlxFe12-2xO19 nanoferrites

This investigation centres on the sol-gel preparation of M-type barium hexagonal ferrite (M-BaFe12O19) incorporating Co2+ and Al3+ as dopants. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were employed to assess the impact of dopants on the crystallographic structure and microstructure. The dielectric characteristics, electric modulus, impedance, and conductivity of the synthesized materials were evaluated at ambient temperature using an impedance analyzer. The structural analysis verified the presence of the hexagonal M-type crystal phase. Increasing dopant levels led to a reduction in lattice parameters, signifying unit cell shrinkage. FESEM imaging exposed the emergence of needle-shaped grains resulting from the doping process. Dielectric spectroscopy showed a decrease in both the dielectric constant (from 135.95 at x = 0.0 to 39.8) and the loss tangent (from 3.68 to 0.610) as dopant concentration increased. Conductivity exhibited relaxation at varying intervals, supported by the electric modulus spectra, which validated non-Debye relaxation behavior. Both relaxation time and AC conductivity diminished with higher dopant concentrations (from 0.000222 Ωm−1 to 0.000036 Ωm−1). The relaxation observed in conductivity and dielectric responses implies their contribution to the charge transport processes within BaCoxAlxFe12-2xO19. Electrochemical impedance spectroscopy (EIS) software was used to generate complex impedance plots, which aligned with the experimentally obtained impedance values for the synthesized compositions. Micrographs revealed a distribution of grains and grain boundaries that were consistent with calculated characteristics. This further substantiates the measured dielectric and electrical parameters.

Computational study on the electrical conductivity of hybrid composites under mechanical deformation

This study explores the hybrid composite’s electrical conductivity response under uniaxial tensile strain, wherein conductive nanowires and insulating particulate fillers are integrated within a flexible polymer matrix. We develop a Monte Carlo–based computational model and analyze the significant influence of particulate fillers on the strain response of the electrical conductivity. The particulate fillers induce both the exclusive volume and nanowire bending effects, significantly contributing to determining the hybrid composites’ electrical conductivity. The exclusive volume effect mitigates conductivity changes under external deformation, decreasing the conductivity change rate as the particulate filler content increases when the exclusive volume effect is dominant. Conversely, the nanowire bending effect boosts conductivity change under external deformation, so when it predominates over the exclusive volume effect, the conductivity change rate increases with higher particulate filler content. The insights from the study aid in designing and optimizing flexible electronic materials resilient to mechanical deformation.

Dietary NO3− does not enhance endothelial dependent cutaneous vascular conductance in older women

Prior work has yet to determine whether the reduction of dietary nitrate (NO3−) to NO, via the enterosalivary pathway, may modify cutaneous vascular conductance (CVC) responses to local heating in older women. Changes occurring with the transition to menopause related to hormonal flux, increased adiposity, and/or decreased physical activity may further compound the negative influence of aging on nitric oxide (NO)-dependent CVC. Herein, we characterized changes in NO-dependent CVC following acute ingestion of 140 mL of NO3−-rich beetroot juice in 24 older women (age: 65 ± 5 y, BMI: 31.2 ± 3.7 kg/m2). Red blood cell (RBC) flux was measured continuously via laser-Doppler flowmetry on the dorsal aspect of the forearm during local skin heating to 39 °C/44 °C before and 3 h after NO3− ingestion. NO-dependent changes in CVC were calculated as RBC flux/mean arterial blood pressure at 39 °C and normalized as a proportion of maximal CVC at 44 °C (%CVCmax). Changes (Δ) in fractional exhaled NO (FeNO) following NO3− ingestion were used an index of NO bioavailability. Despite increased FeNO (+81 ± 70 %, P < 0.001), %CVCmax at 39 °C was reduced (−16 ± 10 %, P < 0.001) following NO3− ingestion. A greater reduction in %CVCmax was weakly to moderately associated with higher body fat% (r = 0.45 [0.05–0.72], P = 0.029), central adiposity% (r = 0.50 [0.13–0.75], P = 0.012), neutrophil% (r = 0.42 [0.02–0.70], P = 0.041), and higher neutrophil to lymphocyte ratio (r = 0.49 [0.11–0.75], P = 0.016). These findings demonstrate a single dose of dietary NO3− does not promote CVC responses to local heating in sedentary older women with overweight and obesity. Correlation with multiple biomarkers suggest systemic inflammation may be involved.

Does Embodying a Divine Avatar Influence Moral Decisions? An Immersive Virtual Reality Study.

The term Proteus effect refers to the changes in attitudes and behavior induced by the characteristics of an embodied virtual agent. Whether the effect can extend to the moral sphere is currently unknown. To deal with this issue, we investigated if embodying virtual agents (i.e., avatars) with different characteristics modulate people's moral standards differentially. Participants were requested to embody an avatar resembling the Christian God in His anthropomorphic appearance or a control human avatar and to perform a text-based version of incidental and instrumental dilemmas in a virtual environment. For each participant, we recorded (1) chosen options (deontological vs. utilitarian), (2) decision times, (3) postdecision feelings, and (4) physiological reactions (skin conductance response and heart rate). We found that embodying God vs. a control avatar did not change the performance in the moral dilemma task, indicating that no strong Proteus effect was at play in our experimental conditions. We interpreted this result by examining the constraints and limitations of our task, reasoning about the necessary conditions for eliciting the Proteus effect, and discussing future developments and advances in the field. Moreover, we presented compelling effects concerning dilemma type, chosen option, personality traits, and religion affiliation, thus supporting and extending literature on decision making in moral dilemmas.

Sleep deprivation increases the generalization of perceptual and concept-based fear: An fNIRS study

Insufficient sleep can initiate or exacerbate anxiety by triggering excessive fear generalization. In this study, a de novo paradigm was developed and used to examine the neural mechanisms governing the effects of sleep deprivation on processing perceptual and concept-based fear generalizations. A between-subject design was adopted, wherein a control group (who had a typical night's sleep) and a one-night sleep deprivation group completed a fear acquisition task at 9:00 PM on the first day and underwent a generalization test the following morning at 7:00 AM. In the fear acquisition task, navy blue and olive green were used as perceptual cues (P+ and P−, respectively), while animals and furniture items were used as conceptual cues (C+ and C−, respectively). Generalization was tested for four novel generalized categories (C+P+, C+P−, C−P+, and C−P−). Shock expectancy ratings, skin conductance responses, and functional near-infrared spectroscopy were recorded during the fear acquisition and generalization processes. Compared with the group who had a typical night's sleep, the sleep deprived group showed higher shock expectancy ratings (especially for P+ and C−), increased oxygenated hemoglobin in the dorsolateral prefrontal cortex, and increased activation in the triangular inferior frontal gyrus during the generalization test. These findings suggest that sleep deprivation increases the generalization of threat memories, thus providing insights into the overgeneralization characteristics of anxiety and fear-related disorders.

Aversive contexts enhance defensive responses to conditioned threat.

The ability to flexibly transition between defensive states is crucial for adaptive responding in life-threatening situations. Potentially threatening situations typically induce a sustained feeling of apprehension in association with hypervigilance, while acute threat is usually characterized by an intense and transient response to cope with the imminent danger. While potential and acute threat states have traditionally been viewed as mutually exclusive, this distinction is being challenged by a growing body of evidence suggesting a more complex interplay during simultaneous activation of these states. However, the interaction between potential and acute threat on a psychophysiological level remains elusive. To fill this gap, 94 healthy individuals participated in one of two contextual fear-conditioning paradigms. In both paradigms, a differential fear-learning phase was conducted, followed by a test phase in which the conditioned stimuli were presented in front of either conditioned or inherently aversive contextual images compared to neutral contexts. To capture defensive responses, we recorded subjective (threat and expectancy ratings) and physiological (electrodermal and cardiovascular) activity to the conditioned stimuli as a function of contextual threat. Besides indices of successful fear conditioning, our results revealed stronger threat and unconditioned stimulus expectancy ratings, cardiac deceleration, and skin conductance responses for threat and safety cues presented in inherently aversive compared to neutral contexts. Conditioned contexts had less impact on physiological responses to threat and safety cues than inherently aversive contexts. These findings provide new insights into the additive nature of defensive responses to fear cues and situations of contextual threat.

Stomatal CO2 responses at sub- and above-ambient CO2 levels employ different pathways in Arabidopsis.

Stomatal pores that control plant CO2 uptake and water loss affect global carbon and water cycles. In the era of increasing atmospheric CO2 levels and vapor pressure deficit (VPD), it is essential to understand how these stimuli affect stomatal behavior. Whether stomatal responses to sub-ambient and above-ambient CO2 levels are governed by the same regulators and depend on VPD remains unknown. We studied stomatal conductance responses in Arabidopsis (Arabidopsis thaliana) stomatal signaling mutants under conditions where CO2 levels were either increased from sub-ambient to ambient (400 ppm) or from ambient to above-ambient levels under normal or elevated VPD. We found that guard cell signaling components involved in CO2-induced stomatal closure have different roles in the sub-ambient and above-ambient CO2 levels. The CO2-specific regulators prominently affected sub-ambient CO2 responses, whereas the lack of guard cell slow-type anion channel SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) more strongly affected the speed of above-ambient CO2-induced stomatal closure. Elevated VPD caused lower stomatal conductance in all studied genotypes and CO2 transitions, as well as faster CO2-responsiveness in some studied genotypes and CO2 transitions. Our results highlight the importance of experimental setups in interpreting stomatal CO2-responsiveness, as stomatal movements under different CO2 concentration ranges are controlled by distinct mechanisms. Elevated CO2 and VPD responses may also interact. Hence, multi-factor treatments are needed to understand how plants integrate different environmental signals and translate them into stomatal responses.

Tunable metamaterials with carrier-induced effective permittivity for active control of electromagnetic fields in semiconductor manufacturing device

Precise control of electromagnetic fields is critical in many advanced manufacturing processes, such as those used in the semiconductor industry, where device performance relies on precision and uniformity. Here, we introduce a solution to control electromagnetic fields via permittivity modulation without the limitations of resonance-based approaches, through a patterned semiconductor enabling permittivity tuning via carrier-density modulation. This carrier-responsive metamaterial (CRM) exhibits frequency-independent performance over a broad frequency spectrum and significant permittivity tunability through controlled semiconductor conductivity. Furthermore, the conductivity response and the tuning range can be easily modulated through the variation of semiconductor materials and geometrical parameters. We present an intuitive model that explains the relationship between the CRM’s structure and properties, including its effective permittivity and loss tangent. Supported by comprehensive simulations and experimental validations, our findings show that the effective permittivity can be increased by over 3.5 times with low dielectric loss across a wide frequency range. As an application, we explore the CRM’s potential in plasma control, revealing its ability to influence plasma density nearly 30% by modulating its effective permittivity, exhibiting CRM’s versatile functionality and potential impact across diverse technological domains.