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A conifer metabolite corrects episodic ataxia type 1 by voltage sensor–mediated ligand activation of Kv1.1
Loss-of-function sequence variants in KCNA1 , which encodes the voltage-gated potassium channel Kv1.1, cause Episodic Ataxia Type 1 (EA1) and epilepsy. Due to a paucity of drugs that directly rescue mutant Kv1.1 channel function, current therapeutic strategies for KCNA1 -linked disorders involve indirect modulation of neuronal excitability. Native Americans have traditionally used conifer extracts to treat paralysis, weakness, and pain, all of which may involve altered electrical activity and/or Kv1.1 dysfunction specifically. Here, screening conifer extracts, we found that Chamaecyparis pisifera increases wild-type (WT) Kv1.1 activity, as does its prominent metabolite, the abietane diterpenoid pisiferic acid. Uniquely, pisiferic acid also restored function in 12/12 EA1-linked mutant Kv1.1 channels tested in vitro. Crucially, pisiferic acid (1 mg/kg) restored WT function in Kv1.1 E283K/+ mice, a model of human EA1. Experimentally validated all-atom molecular dynamics simulations in a neuron-like membrane revealed that the Kv1.1 voltage-sensing domain (VSD) also acts as a ligand-binding domain akin to those of classic ligand-gated channels; binding of pisiferic acid induces a conformational shift in the VSD that ligand-dependently opens the pore. Conifer metabolite pisiferic acid is a promising and versatile therapeutic lead for EA1 and other Kv1.1-linked disorders.
Decoupling evolution of water footprint of energy and its driving factors: Evidence from Northeast China
Energy and water are interlinked and inseparable resources of vital importance to the survival and development of human society. Exploring the relationship between energy and water is of great practical significance for the sustainable development of resources. The uneven regional distribution of energy and water in China has exacerbated energy-related water shortages. Base on the water footprint of energy (WFE), this paper takes Northeast China, the old industrial base, as the research object, and explores the regional distribution characteristics and development trend of WFE, so as to provide quantitative basis for the development of regional energy transformation in coordination with energy and water. This study uses the ISO model and the decoupling model, and analyzes the spatial and temporal changes in the water footprint (WF) of energies and the decoupling effects in Northeast China from the perspective of energy production. The findings show: (1) the WFE grew slowly, and the WF of power gradually exceeded that of fossil energy; (2) the spatial distribution of WFE was unbalanced, with higher WF of fossil energy in Heilongjiang and higher WF of power in Jilin and Liaoning; (3) the decoupling status of WFE from GDP was better than that of WFE from total water consumption. This study also analyzes the driving factors of indicators of water endowment, economic development, energy consumption, environmental governance and life quality, on the WFE based on the Lasso model, and provide policy implications for the coordinated development of energy and water in Northeast China.
Deciphering mixed infections by plant RNA virus and reconstructing complete genomes simultaneously present within-host
Local co-circulation of multiple phylogenetic lineages is particularly likely for rapidly evolving pathogens in the current context of globalisation. When different phylogenetic lineages co-occur in the same fields, they may be simultaneously present in the same host plant (i.e. mixed infection), with potentially important consequences for disease outcome. This is the case in Burkina Faso for the rice yellow mottle virus (RYMV), which is endemic to Africa and a major constraint on rice production. We aimed to decipher the distinct RYMV isolates that simultaneously infect a single rice plant and to sequence their genomes. To this end, we tested different sequencing strategies, and we finally combined direct cDNA ONT (Oxford Nanopore Technology) sequencing with the bioinformatics tool RVhaplo. This method was validated by the successful reconstruction of two viral genomes that were less than a hundred nucleotides apart (out of a genome of 4450nt length, i.e. 2–3%), and present in artificial mixes at a ratio of up to a 99/1. We then used this method to subsequently analyze mixed infections from field samples, revealing up to three RYMV isolates within one single rice plant sample from Burkina Faso. In most cases, the complete genome sequences were obtained, which is particularly important for a better estimation of viral diversity and the detection of recombination events. The method described thus allows to identify various haplotypes of RYMV simultaneously infecting a single rice plant, obtaining their full-length sequences, as well as a rough estimate of relative frequencies within the sample. It is efficient, cost-effective, as well as portable, so that it could further be implemented where RYMV is endemic. Prospects include unravelling mixed infections with other RNA viruses that threaten crop production worldwide.
Electronic properties of MAPb<i>x</i>Sn1−<i>x</i>I3 hybrid perovskite alloys: k.p modeling for tetragonal crystal symmetry with C4<i>v</i> point group
MAPb x Sn 1 − x I 3 alloys are highly promising for photovoltaic, optoelectronic, and spintronics applications. Using k.p calculations, we derived the fundamental band parameters of these tetragonal hybrid halide perovskites as a function of Pb content (x). Our study focuses on the experimentally confirmed C4v point group structures: P4mm for Sn-rich alloys and I4cm for Pb-rich alloys. Our theoretical model successfully reproduces the non-monotonic behavior of the bandgap and provides detailed insights into the electron, hole, and reduced exciton masses (me, mh, and μ). We find that hole masses are slightly larger than electron masses, with both increasing linearly as x rises. At the structural transition (x=0.5) between P4mm and I4cm, we observe a discontinuity in hole masses and a steeper linear increase in Pb-rich structures. The calculated exciton masses show excellent agreement with experimental data across a wide range of alloy compositions. Additionally, we predict the Landé g-factors for charge carriers (ge, gh) and excitons (gX). For Pb-rich alloys, ge increases with decreasing bandgap energy, while for Sn-rich alloys, ge decreases. Exciton g-factors gX are predominantly governed by the large positive ge values, as the smaller negative gh values provide minimal compensation. Consequently, gX is not constant but varies with the bandgap, ranging from 2.4 and 4.8 for Pb-rich alloys and from 4.8 and 3.7 for Sn-rich alloys. These results highlight the tunable electronic and spin properties of MAPbxSn1−xI3 alloys, positioning them as versatile candidates for next-generation device applications.
Association between cardiometabolic index and overactive bladder in adult American women: A cross-sectional study
Background Overactive bladder (OAB) is a common disorder, particularly in women, and its symptoms, including urgency, frequency, and nocturia, can significantly affect quality of life. The cardiometabolic index (CMI) is a novel metabolic risk indicator that has been receiving more attention lately. This study investigated the association between CMI and OAB in adult women. Methods A cross-sectional analysis was performed using data from the National Health and Nutrition Examination Survey (NHANES) covering the years 2007 to 2018, including 6323 female participants. CMI was calculated based on waist-to-height ratio, triglyceride, and HDL cholesterol levels, while OAB was assessed using the overactive bladder symptom score (OABSS). The association between CMI and OAB was evaluated through multivariate logistic regression, generalized additive models (GAM), smoothing curve fitting, and subgroup analysis. We finally included male participants for sensitivity analysis. Results A significant positive association was found between female CMI and OAB prevalence (OR = 1.46, 95% CI: 1.29–1.65). When compared to the lowest CMI quartile (Q1), women in the highest CMI quartile were 70% more likely to have OAB (OR = 1.70, 95% CI: 1.42–2.04). Smoothed curve fitting analysis showed a linear association between CMI and OAB. Subgroup analysis revealed that the association between CMI and OAB was stronger in women aged 20–50 years as well as in women without hypertension. Sensitivity analysis confirmed the robustness of our result. Conclusion CMI was significantly and positively associated with the prevalence of OAB, especially in women aged 20–50 years without hypertension. This finding provides a new perspective on metabolic risk management and may contribute to the early prevention and improvement of bladder function in women.
Anomalous phonon thermal transport in boron chalcogenides: Role of four-phonon scattering
We report the phonon thermal transport properties of two-dimensional (2D) and bulk boron chalcogenides using the density functional theory-driven Boltzmann transport equation approach by considering three- and four-phonon scatterings. The calculated thermal conductivities for 2D boron sulphide (BS), boron selenide (BSe), and boron telluride (BTe) at 300 K are 210, 57, and 125 W/m K and vary non-monotonically with the chalcogen mass. The effect of four-phonon scattering is significant in all materials and the obtained thermal conductivities are overpredicted by as much as 83% when only three-phonon scattering is included. For bulk BS, the four-phonon scattering is significant for the cross-plane direction (64% reduction in thermal conductivity with four-phonon scattering) while the basal-plane transport stays unaffected (∼10% change). The phonons contributing to the cross-plane thermal transport in bulk BS has similar mean free paths as those for basal-plane transport, despite the two orders of magnitude lower thermal conductivity in the cross-plane direction.
The relationship between social safeness and pleasure and resilience levels among university athletes: A descriptive study
This study investigates the correlation between social safeness and pleasure and resilience among university students engaged in sports. A total of 350 participants (mean age, 21.09 ± 3.12 years), comprising 239 females and 111 males, were included in the sample. Data collection utilized the "Social Safeness and Pleasure and Resilience Scales". Normality of data was assessed using skewness and kurtosis tests, confirming normal distribution. Pairwise comparisons were conducted using t-tests, multiple comparisons via one-way ANOVA, and relationship analysis employed Pearson Product Moment Correlation. Findings indicate participants scored above mid-level on the social safeness and pleasure scale (Mean = 2.6), and resilience scale (Mean = 3.7). Specifically, social support dimension mean score was above mid-level (Mean = 4.01), emotional coping (Mean = 3.4), and situational coping (Mean = 3.8). Pearson Product Moment Correlation revealed a statistically significant positive relationship between social safeness and pleasure scale scores and resilience scale scores (r = .652, p < .001). This descriptive study sheds light on the interplay between social and emotional factors and resilience among university athletes.
Shock compression of [101¯0]-axis zinc single crystal
Zinc single crystals have been shocked by planar impact along the [101¯0] axis as well as in the off-axis direction. The evolution of compression waves has been analyzed from the free surface velocity profiles of zinc single crystal samples. A slip on the primary system is activated by impact loading in directions making angles of θ = 17°–64° with respect to the [101¯0] axis. The phenomenon of the formation of two plastic compression waves propagating at different velocities is observed in samples oriented at angles of 53° and 64°. The spall fracture of single crystal zinc samples oriented in different directions has been measured. It is shown that the highest value of spall strength is recorded along the highly symmetric axis of the crystal. The experimental results presented are consistent with the data published in the scientific literature on beryllium and magnesium and confirm the important role of crystalline anisotropy in the process of inelastic deformation of single crystals.
Nutritional assessment of adolescents: A cross-sectional study from public schools of North India
Background Technological advancements and globalization have shifted dietary behaviours, contributing to increased chronic disease prevalence in Low- and Middle-Income Countries (LMICs) like India. Adolescents are particularly vulnerable due to these changes, which can impact their lifelong health. This study aimed to assess the nutritional status of adolescents in public schools in Chandigarh, India. Methodology Conducted as part of a cluster randomized control trial, the study used two-stage random sampling to select 12 schools and eighth-grade classes, recruiting 453 adolescents aged 10–16 years. Nutritional status was evaluated through dietary behaviour assessments, anthropometric measurements, and 24-hour urinary salt-level analysis. Dietary patterns were recorded using two 24-hour recalls, and analyzed with PURE study software based on 2010 Indian dietary data from ICMR-NIN. Anthropometric measures followed standardized protocols, and salt levels were assessed in laboratories. Results The mean age of the adolescents was 13.06 years, with 55% being boys. Among them, 32% had high salt intake, and 55% had high sugar intake. Additionally, 90% had low fruit intake, and 83% had low vegetable intake. The adolescents were deficient in several macro and micronutrients, including energy, fats, fibre, iron, zinc, iodine, riboflavin, and vitamins B-6 and B-12. A higher proportion of boys (10%) were classified as thin compared to girls (2%), while a greater proportion of girls (36%) had abdominal obesity. In contrast, a larger proportion of boys (23%) were severely acutely malnourished. Nearly all adolescents exhibited high urinary excretory salt levels. Conclusion Most adolescents exhibited dietary risk factors, including high salt and sugar intake, along with low consumption of fruits and vegetables. Many were deficient in various macro and micronutrients, with the coexistence of both thinness and obesity. Regular nutritional assessments in schools are essential to address the dual burden of undernutrition and overnutrition. Furthermore, health-promoting interventions should be developed within school settings to encourage healthy dietary practices.
Piezoelectric thin films and their applications in MEMS: A review
With the increasing demand for devices in miniaturization, accuracy, and low power consumption, developing microdevices in the form of piezoelectric thin films is significant for microelectromechanical systems (MEMS) applications. Piezoelectric thin films offer advantages of miniaturization and low power consumption, holding immense potential in MEMS, especially with advancements in micro-nanomanufacturing technologies. In this review, we highlighted the compelling piezoelectric properties and summarized the latest research progress of thin films, with an emphasis on recent advances in piezoelectric MEMS. We mainly introduced the recent developments on different types of piezoelectric MEMS (piezo-MEMS), along with the descriptions of piezoelectric effects, film preparation, film properties, and device indicators. We have emphasized the comparison of MEMS with different piezoelectric materials and methods for improving devices. The recent achievements of piezoelectric thin films in MEMS applications and the future development of MEMS applications are also reviewed.
Does curcumin supplementation affect inflammation, blood count and serum brain-derived neurotropic factor concentration in amateur long-distance runners?
Curcumin is known for its potential health benefits; however, the evidence remains inconclusive regarding its necessity as a supplement for athletes during the preparatory phase of training. This study aimed to assess the effect of 6-week curcumin supplementation at a dose of 2g/day on selected inflammatory markers, blood count, and brain-derived neurotropic factor (BDNF) levels in middle-aged amateur long-distance runners during the preparatory period of a macrocycle. Thirty runners were randomly assigned to either a curcumin-supplemented group (CUR, n = 15) or a placebo group (PLA, n = 15). Venous blood samples were collected at rest, immediately post-exercise, and 1h post-exercise. The participants underwent a graded exercise stress test, with an increasing inclination angle after reaching a speed of 14 km/h, both before and after the 6-week supplementation period. Blood samples were collected at rest, 3 minutes post-stress test, and after 1 hour of recovery. The results showed no significant changes in C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), interleukin-1 β (IL-1β), or blood morphology due to curcumin supplementation. However, BDNF levels increased by 21% in the CUR group post-supplementation, while a 5% decrease was observed in the PLA group. These findings do not support a significant effect of curcumin supplementation on inflammatory markers, blood count, or BDNF concentration. Further research is warranted to determine the potential benefits of curcumin supplementation for endurance athletes during the preparatory period for a training cycle.
Design of miniaturized and polarization insensitive frequency selective surface filter with large band ratio
In this paper, a miniaturized and polarization insensitive frequency selective surface filter with large band ratio (BR) is presented. This structure consists of one metal layer and two dielectric layers. The metal layer includes two parts, with the outer square loop providing a lower frequency stopband and the inner pattern providing a higher frequency stopband. The structure has excellent miniaturization characteristics, in particular, the unit size is only 0.054λ0 and the thickness is only 0.014λ0, where λ0 is the wavelength corresponding to the first resonant frequency. Additionally, there is only one layer of metal layer, which greatly reduces the processing complexity and cost. The measurement results show that for TE and TM polarization, the center frequencies of the two stop bands are 2.03 and 18.98 GHz corresponding to a BR of 9.35. It can be used as a spatial dual frequency filter with large frequency band separation. In addition, the proposed structure also possesses advantages such as wideband response, polarization insensitivity, and high angle stability. The simulation results are in good agreement with the measured results.
Ankle muscle strength and activation are associated with walking patterns in preschool and school-age children
Walking patterns can differ between children and adults, both kinematically and kinetically. However, the detailed nature of the ankle pattern has not been clarified. We investigated musculature, biomechanics, and muscle activation strategies and their relevance to walking performance in preschool (PS) and school children (SC), with adults (AD) as reference. Twenty-six PS (3–5 yr), 20 SC (6–8 yr), and 17 AD (18–30 yr) participated. Tibialis anterior (TA) and medial gastrocnemius (MG) thicknesses, fascicle lengths, and maximal voluntary dorsi- and plantar flexion isometric torques were measured. Hip, knee, and ankle kinematics, ground reaction forces (GRFs), and TA and MG electromyographic activities were recorded during shod walking at each participant’s preferred speed. Walking speed, step length, and cadence were correlated with age in PS. These walking performance measures were also correlated with muscle thickness and fascicle length, showing higher speed in individuals with thicker muscles and longer TA and MG fascicles (conversely, higher cadence with thinner muscles and shorter fascicles). AD demonstrated the largest values for muscle thickness (p<0.001), fascicle length (p<0.001), strength (p<0.001), and walking performance (speed p = 0.004; step length p<0.001; cadence p<0.001), followed by SC then PS. Both PS and SC exhibited higher TA activities than AD during the stance phase, resulting in a higher co-activation index. The GRFs relative to body weight were lower in both horizontal and vertical components in PS compared to SC and AD, while the relative lateral force during stance was greatest in PS followed by SC and then AD. Differences in preferred walking speed and step length were associated with age and muscle size. Children, particularly preschool-aged, employed a co-activation strategy of dorsi- and plantar flexors for stabilization, which resulted in sideways steps even at a preferred walking speed.
Investigation on coupling between ferro-orderings and energy harvesting properties of nickel ferrite and strontium modified barium titanate composites
Environment-friendly, low power-consuming magnetoelectric composites possess the interesting coupling between various ferro-order parameters and find applications in magnetic sensors, waveguides, transducers, spintronics, four-state memory devices, etc. The particulate composites (x)NiFe2O4–(1 − x)Ba0.9Sr0.1TiO3 were prepared using the hybrid sol-gel method using the conventional ceramic double-sintering method. The ferromagnetic nickel ferrite crystallized into a cubic crystal structure whose x-ray diffraction (XRD) peaks could be indexed to Fd3¯m space group. The ferroelectric strontium-substituted barium titanate crystallized to a tetragonal crystal structure with P4mm space group. Presence of both crystal symmetries and elemental compositions as per the proposed stoichimetry were observed from experimental results (XRD and electron microscopy techniques). Koop's phenomenological theory could be employed to explain the impedance spectra in the range of 1 kHz to 1 MHz. The effect of Maxwell–Wagner polarization and space charge polarization on the dielectric properties of composites have been observed. The Arrott plot technique successfully explains the suitability of composites for high-energy storage applications. The coupling between both ferro-orderings has been revealed from the magneto-dielectric curves and its dependency on the microstructure has been observed. The magnetocapacitance increased with the increase in NiFe2O4 composition in the (x)NiFe2O4–(1 − x)Ba0.9Sr0.1TiO3 composite. The 30% NiFe2O4 in (x)NiFe2O4–(1 − x)Ba0.9Sr0.1TiO3 composite exhibited overall better energy harvesting (η = 62.9%) and magnetodielectric properties (MC = 1.4%, MI = 20% at 1 kHz).
Machine learning approach to student performance prediction of online learning
Student performance is crucial for addressing learning process problems and is also an important factor in measuring learning outcomes. The ability to improve educational systems using data knowledge has driven the development of the field of educational data mining research. Here, this paper proposes a machine learning method for the prediction of student performance based on online learning. The critical thought is that eleven learning behavioral indicators are constructed according to online learning process, following that, through analyzing the correlation between the eleven learning behavioral indicators and the scores obtained by students online learning, we filter out those learning behavioral indicators that are weakly correlated with student scores, meanwhile, retain these learning behavior indicators being strongly correlated with student scores, which are used as the eigenvalue indicators. Finally, using the eigenvalue indicators to train the proposed logistic regress model with Taylor expansion. Experimental results show that the proposed logistic regress model defeats against the comparative models in prediction ability. Results also indicate that there is a significant dependency between students’ initiative in learning and learning duration, nevertheless, learning duration has a significant effect on the prediction of student performance.
Crystalline–disordered–crystalline transition in nitrogen–carbon materials
Nitrogen–carbon (N–C) materials range from graphitic carbon nitride (g-CN) to graphite with nitrogen defects. Between these two crystalline extremes lies a spectrum of semi-crystalline and disordered materials. The question is whether these structural transitions are related to material’s composition, and if yes, how? Here, we answer these questions based on experimental and computational investigations on the structural evolution in N–C systems and their correlation with the chemical and electronic properties. Crystalline g-CN is used as the starting material with a systematical reduction in its N-content through heat treatment. As the N-content reduces, crystalline g-CN transitions into N-containing disordered carbons followed by N-containing graphitic carbons. The experimentally deduced electronic properties of the N–C systems with decreasing N-content are validated by theoretical methods using Density Functional Theory (DFT) approach. A qualitative match between the experimentally deduced and theoretically computed electronic properties indicate crystalline to disordered to crystalline structures in such materials at two noticeable transition points around the N/C ratios of 0.35 and 0.17, respectively.
Study on the effect of water content on physical properties of bentonite
Moisture content profoundly influences the engineering properties of expansive soil, a critical consideration in various geotechnical applications. This study delves into the intricate relationship between water content and the physical properties of bentonite, a key constituent of expansive soil. Through a comprehensive analysis encompassing fundamental physical properties, rheological characteristics, permeability behavior, and microscopic features, we elucidate the complex interplay between water content and bentonite behavior. Our investigation reveals distinct responses to varying moisture levels: at low water content (w = 50%), unsaturated samples undergo incremental density increases attributed to moisture accumulation among particles. Concomitantly, heightened pressure fosters enhanced cohesion between particles, bolstering mechanical properties and augmenting reverse osmosis capacity. Conversely, at higher water content levels (w > w saturated), the escalation of free water within soil particles triggers pronounced particle softening, overshadowing expansion effects. Consequently, cohesion diminishes, and particles exhibit micro-scale flocculation. These findings offer valuable insights into bentonite behavior under differing moisture regimes, thereby providing a robust theoretical foundation for projects requiring bentonite seepage control.
Impact of Ga overpressure on the metal modulation epitaxy growth of AlN/AlGaN short period superlattices
The formation of AlN/AlGaN short period superlattices (SPSLs) was investigated though the introduction of a constant Ga overpressure during the metal modulated epitaxy (MME) growth of AlN. A combination of x-ray diffraction (XRD) and scanning transmission electron microscopy (STEM) analyses found that control over the Al composition in the AlGaN layer was achieved through modulating the Ga beam equivalent pressure (BEP), with a minimum partial pressure of 3 × 10−7 Torr needed for Ga to incorporate at a growth temperature of 825 °C. A minimum Al composition in the AlGaN layer of 72% was achieved for a Ga BEP of 1 × 10−6 Torr using this method. An apparent limit of the AlGaN layer thickness of 3–4 ML indicated that the incorporation of Ga was confined to the consumption region of the MME growth process. Determination of this behavior made clear the requirements of having both XRD and STEM in order to be able to fully characterize the SPSL layer structure. Finally, AFM imaging highlighted that the presence of Ga on the surface behaved as a surfactant, with a minimum RMS roughness of 0.46 nm achieved at the maximum Ga BEP of 1 × 10−6 Torr.
Acceptability of a dapivirine levonorgestrel vaginal ring in two Phase 1 trials (MTN-030/IPM 041 and MTN-044/IPM 053/CCN019): Implications for multipurpose prevention technology development
End-user feedback early in product development is important for optimizing multipurpose prevention technologies for HIV and pregnancy prevention. We evaluated the acceptability of the 90-day dapivirine levonorgestrel ring (DPV-LNG ring) used for 14 days compared to a dapivirine-only ring (DVR-200mg) in MTN-030/IPM 041 (n = 23), and when used for 90 days cyclically or continuously in MTN-044/IPM 053/CCN019 (n = 25). We enrolled healthy, non-pregnant, HIV-negative women aged 18–45 in Pittsburgh, PA and Birmingham, AL (MTN-030 only). Self-reports of vaginal bleeding and adherence (ring removals, expulsions) were collected via daily short message service. Acceptability data were recorded in face-to-face interviews at study exit. We assessed differences in acceptability by product characteristics and adherence; and associations between baseline characteristics/demographics, number of bleeding days, adherence, and overall acceptability. Most (21/23) women in the 14-day MTN-030 study and about half (13/25) in the 90-day MTN-044 study liked their assigned rings. In MTN-030 there were no significant associations between any variables and overall acceptability of either ring. In MTN-044, women who disliked the DPV-LNG ring had a significantly higher incidence of unanticipated vaginal bleeding, and reporting that vaginal bleeding changes were unacceptable than those who liked it. Although we found no overall association between adherence and acceptability, significantly more women who disliked (versus liked) the DPV-LNG ring reported expulsions during toileting. The DPV-LNG ring could meet the needs of women seeking simultaneous protection from HIV and unintended pregnancy. Addressing issues related to vaginal bleeding and expulsions early in product development will likely enhance acceptability of the DPV-LNG ring. Trial registration: Clinical Trial Registration: MTN-030/IPM 041: ClinicalTrials.gov NCT02855346; MTN-044/IPM 053/CCN019: ClinicalTrials.gov NCT03467347.
Tunable piezoresistivity for sensors with antiferromagnetic pure Cr and Cr-rich alloy thin films: Cr–V, Cr–W, Cr–Mn
Sputter-deposited thin films of pure chromium and chromium-rich alloys with V, W, and Mn are evaluated in terms of electrical resistivity and piezoresistivity, as measured by the gauge factor, from room temperature to 470 °C. The alloying elements vanadium, tungsten, and manganese, are known to either stabilize or destabilize the spin-density wave antiferromagnetism found in Cr. In a concentration series and a substrate bias voltage series, the variation of resistivity, gauge factors (of up to 20), and their temperature coefficients is shown. High-temperature resistivity measurements indicate increased Néel transition temperatures that are related to a gauge factor maximum. Generally, the gauge factor increases toward the Néel temperature. The Cr60Mn40 film, however, has a small negative temperature coefficient of the gauge factor. This is a desired property in strain and pressure sensor films, as it allows for compensating the temperature coefficient of the elastic modulus of aluminum or steel transducers. An analysis of the resistance change through mechanical loading quantifies Néel temperature changes of up to 100 K per percent of strain that are likely the mechanism of the observed piezoresistivity. Overall, the Cr-rich alloy thin films represent a class of metallic piezoresistive films with properties that can be well adjusted to the sensor application by concentration and sputtering parameters.