Endurance Behavior Research Articles

PVA nanocomposite hydrogel loaded with silver nanoparticles enriched Nigella sativa oil

Nigella sativa oil [NSO] was enriched with biosynthesized silver nanoparticles [NP] by simple, cost-effective, and less time-consuming “Green Chemistry” protocol. This combination [NSO/NP], on blending with PVA, produced transparent and foldable hydrogel film. The structure, morphology, hydrophilicity and thermal stability of hydrogel film confirmed the incorporation of inorganic NP in organic PVA matrix. FTIR spectrum of nanocomposite film revealed good interactions between PVA matrix, NP and NSO. SEM of PVA and NSO combination film exhibited lipidic NSO cloud-like phase (light grey) dispersed in PVA matrix (dark contrast), while in nanocomposite hydrogel film these lipidic clouds disappeared completely, and PVA matrix appeared donning a grey sheath. The nanocomposite film showed good folding endurance (> 300 folds) and antimicrobial behavior against Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATTC 29212), Escherichia coli (ATCC 26922), Pseudomonas aeruginosa (ATCC 27853), Proteus mirabilis (ATCC 29906), Klebsiella pneumonia (MTCC109), Acinetobacter baumannii (NCTC 12156), and Candida albicans (ATCC90028) with prospective applications in antimicrobial packaging and wound dressings.

Investigation of Endurance Behavior on HfZrO-Based Charge-Trapping FinFET Devices by Random Telegraph Noise and Subthreshold Swing Techniques

The HfZrO-based charge-trapping (CT) FinFET (CT-FinFET) devices with CT/de-trapping behavior occurring in the gate-stack provide a possible solution for embedded 1T DRAM application. In this brief, a novel method combining the random telegraph noise (RTN) and subthreshold swing (SS) is developed to investigate the endurance behavior of CT-FinFET devices, and the following advances have been achieved: 1) the traps in the gate-stack have been classified into two types: slow traps inside the HfZrO layer with deep energy level and fast traps at the interface with shallow energy level; 2) as the endurance cycles went on, the depth and energy level of slow traps increased, while the depth and energy level of fast traps kept the same, which indicated that the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> shift is caused by the accumulation of holes' trapping in slow traps inside the HfZrO layer; 3) traps inside the HfZrO layer with deeper energy level and shallower depth can be easily occupied by holes during cycling; and 4) the generation of shallow-level traps at the interface contributes to the memory window (MW) degradation. This provides a useful tool for advancing the CT-FinFET technology.

Determination of fatigue resistance for steels treated inthermal different ways

In this work is presented an experimental programme for the evaluation of the endurance behaviour of steels which are thermally treated in different ways and the identification of micro-cracks which appear in the material. The fatigue limit was defined as he maximum amplitude of alternating symmetrical stress which steel can endure. In addition to the tests described above. The experimental programme analyses also the change f microstructure under the influence of thermal treatment in view of increasing the working life of materials under stress. The knowledge of the relationships between the structural changes, the internal tensions, the mechanical and physical properties of the material also involve the knowledge of the occurrence of the first nano-cracks.

Avoidance and endurance coping after mild traumatic brain injury are associated with disability outcomes.

Objective: Fear-avoidance and endurance behavior are well-established maladaptive coping styles in several chronic health conditions. There is also emerging evidence that both fear-avoidance and endurance coping are associated with poor outcome from mild traumatic brain injury (mTBI). The current study sought to characterize the early trajectories of avoidance and endurance behavior and confirm their association with disability outcomes. Method: Adults with mTBI (N = 88) completed measures of avoidance, endurance, and postconcussive symptoms at clinic intake (M = 40.2 days since injury). Avoidance and endurance measures were readministered 1 month later (N = 79), and a measure of perceived functional disability (World Health Organization Disability Assessment Schedule 2.0) was completed 3 months after clinic intake (N = 69). Results: Avoidance and endurance coping were weakly positively correlated with each other at intake (r = .28) and at 1 month postintake (r = .28). Change scores on these two measures over time were not significantly correlated (r = .04). Avoidance coping tended to decrease over time (95% CI [0.6, 2.5]; p = .002), whereas changes in endurance coping were variable. In generalized linear modeling, higher avoidance and endurance at clinic intake and increasing (or less rapidly decreasing) levels of these coping styles over 1 month was associated with greater perceived disability ratings at 3 months, even after controlling for postconcussion symptom severity at intake. Conclusion: These findings suggest that avoidance and endurance behavior are distinct coping styles with unique trajectories during the subacute recovery period. The results also support the need for psychologically informed early interventions that target specific profiles of maladaptive coping to mitigate risk for poor outcomes post-mTBI. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Improvement of remanent polarization of CeO2–HfO2 solid solution thin films on Si substrates by chemical solution deposition

CeO2–HfO2 solid solution thin films, Hf1−xCexO2, are fabricated on n+-Si(100) substrates by the chemical solution deposition method. The effects of the CeO2 content and annealing temperature on the structure and ferroelectric properties of Hf1−xCexO2 are studied. The structural properties are investigated by glancing incidence x-ray diffraction and high resolution transmission electron microscopy, while the chemical states are examined by x-ray photoelectron spectroscopy. The results reveal that the admixture of CeO2 could effectively induce the ferroelectric phase. For Hf0.85Ce0.15O2 fabricated at an annealing temperature of 800 °C, an enhanced remanent polarization (Pr) of ∼20 μC/cm2 (after correction for leakage and parasitics) could be attained. Moreover, Hf0.85Ce0.15O2 demonstrates good endurance behavior, that the polarization does not show obvious degradation over 1 × 109 bipolar switching cycles, at an electric field of 2.9 MV/cm and a frequency of 100 kHz. This work highlights the importance of CeO2–HfO2 solid solution films in HfO2-based ferroelectric thin films.

Fatigue-less relaxor ferroelectric thin films with high energy storage density via defect engineer

Thin film capacitors with excellent energy storage performances, thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry. Herein, we design and prepare lead-free 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3- x%Mn (x = 0, 0.5, 1.5, 2, 3) thin films via sol-gel method. Mn ions of divalent valence combine with oxygen vacancies, forming defect complex, which results in marked decline in leakage current and obvious enhancement in breakdown strength. A high energy storage density ∼ 47.6 J cm−3 and good efficiency ∼ 65.68 % are simultaneously achieved in 2% Mn doped 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3 thin film capacitor. Moreover, the 2% Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range (35–115 °C) and strong fatigue endurance behaviors after 108 cycles. The above results demonstrate that 2% Mn-doped 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3 thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.

Variability-Aware Modeling of Filamentary Oxide-Based Bipolar Resistive Switching Cells Using SPICE Level Compact Models

Bipolar resistive switching (BRS) cells based on the valence change mechanism show great potential to enable the design of future non-volatile memory, logic and neuromorphic circuits and architectures. To study these circuits and architectures, accurate compact models are needed, which showcase the most important physical characteristics and lead to their specific experimental behavior. If BRS cells are to be used for computation-in-memory or for neuromorphic computing, their dynamical behavior has to be modeled with special consideration of switching times in SET and RESET. For any realistic assessment, variability has to be considered additionally. This study shows that by extending an existing compact model, which by itself is able to reproduce many different experiments on device behavior critical for the anticipated device purposes, variability found in experimental measurements can be reproduced for important device characteristics such as I-V characteristics, endurance behavior and most significantly the SET and RESET kinetics. Furthermore, this enables the study of spatial and temporal variability and its impact on the circuit and system level.

Defects induced resistive switching behavior in Ca doped YMnO3–based non–volatile memory devices through electronic excitations

Defect induced structural, microstructural, resistive switching (RS) characteristics and related responsible charge conduction mechanisms of Y0·95Ca0·05MnO3 (YCMO) manganite films, grown on single crystalline (100) Nb:SrTiO3 (SNTO) substrates (0.2 wt% Nb doped at Ti–site in SrTiO3), are reported in this communication. Films were irradiated by 100 MeV O+7swift heavy ions (SHI) with different ion fluence. Structural studies were performed using X–ray diffraction (XRD) and XRD φ–scan measurements for all pristine and irradiated films. Atomic force microscopy (AFM) measurement was performed to understand the granular morphology and surface modifications in YCMO films due to SHI irradiation. Observed RS behavior has been ascribed to the trapping–detrapping processes, modifications in the depletion region, movement of oxygen vacancies and tunneling process across the interface barriers between YCMO and SNTO. Various models and mechanisms have been employed to understand the observed charge transport across the interfaces. All the films show endurance and retention behaviors that suggest the reproducibility, dynamic stability and reliability of presently studied films as non–volatile memory devices.

A Short-term Longitudinal Study Of The Effectiveness Of Kids Get Fit Fitness And Nutrition Curriculum

PURPOSE: This study investigated the effects of the Kids Get Fit (KGF) fitness (premised on integrative neuromuscular training) curriculum and nutritional education on measures of movement competence, muscular endurance, and dietary behavior in elementary school age children. METHODS: Participants were 4th graders at two local schools (94 ± 2% Hispanic/Latino) in Corpus Christi, Texas, i.e., experimental (n = 69; 31 males) (8.5 ± 0.5 years; 132.6 ± 6.3 cm; 36.3 ± 10.7 kg) and control (n = 40; 14 males) (8.4 ± 1.2 years; 131.7 ± 17.1 cm; 35.7 ± 11.5 kg). KGF instructors delivered an engaging curriculum that included fitness, dance, yoga, and nutritional education to children at the intervention school, while the control school had traditional physical education class across 12 weeks. Movement competence (standing long jump), muscular endurance (90o push-up), and dietary behaviors (EFNEP 3rd-5th Grade Survey) were assessed at baseline and within a week of concluding the intervention. A series of factorial ANOVA and Mann-Whitney U Test was used to explore differences within and between groups. Statistical significance was set at P < .05. RESULTS: There was a significant interaction of time and intervention (F(1,108) = 7.973, P = .006); the control group had higher resting heart rate increase compared to the experimental group. There was a significant interaction of time and intervention (F(1,96) = 8.579, P = .004); the experimental group showed greater increase in standing long jump performance compared to the control group. There was a significant main effect of the intervention (F(1,107) = 6.192, P = .014); the experimental group showed increased 90o push-up performance compared to the control group. There were no significant differences in sugar-sweetened beverage (U = 1311.500, P = .505), vegetable (U = 1399.500, P = .924), and fruit (U = 1341.500, P = .629) consumption between groups after 12 weeks. CONCLUSIONS: Findings suggest the intervention improved muscular endurance and movement competence. Improved stability of resting heart rate suggests favorable cardiovascular effects attributed to enhanced fitness. Lack of differences in dietary behaviors further underscore the importance of involving entire families in nutritional education and addressing access to healthy foods in elementary school age children.

Network endurance against cascading overload failure

Network endurance can be regarded as the upper limit of survival time before the system's complete breakdown, which is highly related to system resilience. Although network endurance against overload failure is critical for network design and operational management, the definition and corresponding evaluation method still remain challenging. In this paper, based on the load-dependent overload model, we define network endurance as the cascade duration at criticality before the complete network breakdown and develop an approach for endurance evaluation. We find that network endurance highly depends on initial disturbance intensity and cascade intensity. The network endurance with a uniform initial load distribution usually monotonically increases with decreasing initial disturbance intensity, while for other initial load distributions endurance behaviors are more complicated. We also provide theoretical analysis for the network endurance. Our findings may help to understand the network reliability mechanism against cascading overload failures and design a highly reliable network.

Body Image in Athletes and Nonathletes With Low Back Pain: Avoidance-Endurance-Related Subgroups and Sports Status Play a Role.

Low back pain (LBP) is a serious health problem, both in the general population as well as in athletes. Research has shown that psychosocial aspects, such as dysfunctional pain responses, play a significant role in the chronification of LBP. Recent research supports the relevance of the multidisciplinary concept of body image in the interpretation of LBP. To examine the differences in 2 psychosocial aspects, body image and pain responses, between athletes and nonathletes with LBP. Cross-sectional design. The questionnaires were distributed in the course of LBP treatment. Data from 163 athletes (mean age = 28.69 [9.6]y) and 75 nonathletes (mean age = 39.34 [12.63]y) were collected. Data were collected by questionnaires assessing body image, pain behavior, training activity, and LBP. To examine group differences between athletes and nonathletes regarding body image and pain behavior, the authors performed 2-way analyses of variance with Bonferroni post hoc tests. The results showed (1)a significant main effect regarding pain responses and body image, showing that participants with eustress endurance or adaptive pain behavior revealed a more positive body image in both groups compared with participants with distress endurance or fear-avoidance behavior, and (2)a significant main effect for the factor group in the body image dimension of physical efficacy, indicating a more positive body image for athletes. These results suggest that considering multiple risk factors for LBP, such as body image and dysfunctional pain behavior, as well as subgrouping, might be valuable for research and for broadening therapy options.

Optimized Resistive Switching in TiO2 Nanotubes by Modulation of Oxygen Vacancy Through Chemical Reduction

The resistive switching behavior of 1-D TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotube-based resistive random access memory (ReRAM) is discussed in this article. Highly oriented TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes were synthesized by anodic oxidation method on a Ti substrate, which was used as the bottom electrode. To modulate the oxygen vacancy (VO) in TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes, hydrazine hydrate reduction was employed in the temperature range 60 °C-100 °C. After charactering the morphological, elemental, and crystallographic properties, the level of reduction in different TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes array was estimated by Raman, photoluminescence, and X-ray photoelectron spectroscopies. Au/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes/Ti devices were fabricated by using TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes with various levels of reductions where thin and porous Au top electrode was used to make the resistive switching faster. TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Nanotubes array, reduced at 80 °C showed promising resistive switching performance with SET/RESET voltages of 2 V/1.8 V, R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> /R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> of 19 at a read voltage of 0.5 V (25 °C) and stable endurance behavior after the 100th cycle. Interestingly, reduction temperature at 60 °C and 100°C, offered degraded resistive switching within the same voltage range. All the devices showed electroforming free bipolar resistive switching. Efforts were devoted to establish the role of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> and its tuning to improve the resistive switching behavior in 1-D TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanotubes. This article systematically showcases the efficacy of 1-D metal oxide for potential ReRAM application and establishes an easy but efficient approach to improve the resistive switching by modulating oxygen vacancy in it.

Enhanced Switching Ratio and Long-Term Stability of Flexible RRAM by Anchoring Polyvinylammonium on Perovskite Grains.

The ON/OFF ratio and long-term stability are two important issues for flexible organic-inorganic hybrid perovskite (OHP) resistive random access memory (RRAM) for practical applications. In this work, polyvinylammonium (PVAm) is applied to partially replace methylamine ions (MA+) to fabricate the stable and flexible polymeric OHP RRAM devices, wherein PVAm acts as nucleation sites and the template for crystalline growth of MAPbI3 to tune the microscopic perovskite structure. Simultaneously, the multiple perovskite grain interfaces are strengthened through the long-carbochain polymeric backbone, hence producing a continuous and compact perovskite film. As a result, the PVAm-modified OHP RRAM device shows remarkable enhancement of the ON/OFF ratio, long-term stability, and flexibility compared with the unmodified OHP device. Specifically, the polymeric OHP device exhibits fast and stable nonvolatile resistive switching (RS) characteristics with an ON/OFF ratio of ∼105 and a set voltage of -0.45 V under ambient conditions. Also, the distinct multilevel RS behavior can be realized in this device by controlling the compliance current in theSET process. Additionally, the unsealed polymeric OHP device manifests the striking long-term stability, which can still maintain the stable memory performance after 1 year exposure to the humid and thermal ambient environment. Furthermore, the flexible polymeric OHP device was also fabricated and affords the excellent bending endurance behavior by showing a reproducible RS property over 100-cycle bending experiments. This work provides a new perovskite-based material design strategy of polymeric OHP for stable and flexible RRAM devices with the high ON/OFF ratio.

Enhanced resistive switching in graphene oxide based composite thin film for nonvolatile memory applications

The uniform and stable bipolar switching characteristics of Graphene Oxide (GO) based metal insulator metal (MIM) structure embedded with titanium dioxide (TiO2) nanoparticles (NPs) on ITO/glass substrate has been investigated. In this paper the effect of TiO2 concentration on switching characteristics of Al/GO-TiO2/ITO MIM devices were studied. Thin film of composite (GO-TiO2) was deposited on conductive indium tin oxide (ITO) glass using spin coating technique. The incorporation of TiO2 NPs in GO thin film increased the number of oxygen vacancies which were responsible for formation and rupture of conducting filament between two electrodes of Aluminum and ITO. It was observed that Al/GO-TiO2 (4 mg)/ITO require low voltage to switch from OFF state (High Resistance State) to ON state (Low Resistance State) and vice versa as compared to Al/GO/ITO device. Switching behavior of the fabricated devices were investigated using current voltage characteristics. The dispersion of TiO2 (4 mg) NPs in GO reduced the switching voltage by almost 50% than the bare graphene oxide thin film. The retention behavior of fabricated device was tested upto 4*103 s and endurance behavior upto 60 cycles which didn’t exhibit any degradation. Carrier transport mechanism in the devices has been explained on the basis of current voltage characteristics in HRS and LRS. These composite based resistive random access memory devices have great potential as a future nonvolatile low power memory.

Dielectric property and energy-storage performance of (100)-preferred (1-x)PbTiO3-xBi(Mg0.5Ti0.5)O3 relaxor ferroelectric thin films

In this work, relaxor ferroelectric thin films (1-x)PbTiO3-xBi(Mg0.5Ti0.5)O3 [(1-x)PT-xBMT, x = 0.4, 0.5 and 0.6] were prepared on LaNiO3/Si(100) (LNO/Si) substrates by sol-gel method. All films exhibit a single perovskite structure and possess high compactness. As the BMT content increases, the diffusion coefficient γ increases from 1.84 to 1.92, indicating the gradually enhanced relaxor behavior. The thin film with x = 0.5 has a lower leakage current density than those of other components, which leads to a high breakdown strength. As a result, an ultrahigh recoverable energy-storage density of 51.0 J/cm3 under 2900 kV/cm was achieved in the thin film with x = 0.5. In addition, the 0.5PT-0.5BMT thin film also exhibited excellent frequency stability and temperature stability, and the both changes rate were less than 2.8%. The outstanding energy-storage performance is attributed to its excellent electric-field endurance and relaxor behavior. This work indicates the 0.5PT-0.5BMT thin films is a potential energy-storage material.

Application of cardiac rehabilitation program based Omaha system in post percutaneous coronary intervention patients

Objective To investigate the effect of the cardiac rehabilitation program based Omaha system on patients after percutaneous coronary intervention (PCI) . Methods A convenient sampling method was used to select 127 patients from the Department of Cardiology of Wuxi Second People's Hospital from October 2017 to April 2018. According to the patient's hospitalization number, they were randomly divided into two groups, including 64 in the experimental group and 63 in the control group. During the intervention, 2 patients were lost in the experimental group and 1 patient was lost in the control group. There were 62 patients in each group to complete the study. Patients in the control group received routine care, while patients in the experimental group received cardiac rehabilitation based on the Omaha system. The effect of the intervention was measured by 6 min exercise test, secondary prevention knowledge and behavior questionnaire for post-PCI patients. Results After the intervention, The 6-minute exercise distance was (439.28±67.94) m in the experimental group, and it was (315.62±45.18) m in the control group. The exercise endurance of the experimental group was higher than that of the control group, and the difference was statistically significant (t=11.934, P<0.01) . The secondary prevention knowledge and behavior scores of the experimental group were (87.21±12.46) and (84.27±14.58) , which were higher than those of the control group (71.30±8.12) and (65.94±8.97) . The differences were statistically significant (t=8.423, 8.431; P <0.01) . Conclusions Cardiac rehabilitation programs based Omaha system can improve exercise endurance and secondary prevention behaviors of patients after PCI and its application should be promoted. Key words: Heart; Rehabilitation; Omaha system; Percutaneous coronary intervention; Exercise endurance; Secondary prevention

Strength, endurance and fatigue response of rotator cuff muscles during isometric exertions

Among the shoulder musculoskeletal disorders (MSDs), rotator cuff disorders are prevalent and known to substantially limit an individual's strength and ability to work. Despite the frequency and cost of rotator cuff injuries, very little research has been done on understanding the load response relationship of rotator cuff muscles. Therefore, this study was aimed at evaluating the strength, endurance and fatigue response of rotator cuff muscles. As a first step, strengths of Supraspinatus, Infraspinatus, and Teres Minor were measured for ten healthy male participants using muscle specific Maximum Voluntary Contractions (MVC). Then, endurance time and surface Electromyography (EMG) data were recorded during 15%, 30%, 45%, and 60% MVC exertions. Infraspinatus exhibited the highest strength followed by Teres Minor and Supraspinatus. Despite the strength differences, small variations were observed in the endurance time between the muscles. The effect of %MVC exertions on endurance time, average muscle activity and muscle fatigue were statistically significant. Median frequency decreased and muscle activation increased with an increase in force exertion levels; however, the changes observed for an increase in the exertion level from 15% to 30% MVC were much higher than the changes observed for an increase in the exertion level from 45% to 60% MVC. Relevance to industryResults of this study indicate that the rotator cuff muscles have different strengths but exhibit very similar endurance and fatigue behavior. These findings can assist ergonomic practitioners with the design and/or evaluation of workplace upper extremity exertions to reduce/manage stress on the rotator cuff muscles and shoulder.

Influence of Frenkel defects on endurance behavior in SnO2:Cu memristors

SnO2:Cu memristor devices were fabricated to investigate the influence of Frenkel defects on endurance behavior. We controlled the oxygen pressure during pulsed laser deposition to obtain different Frenkel defect conditions. For SnO2:Cu devices with homogeneous Frenkel defects, high-resistance state (HRS) fatigue was observed with increasing switching cycles due to the reduction of interfacial barriers caused by unrecoverable fragments of conductive filaments. In bilayer SnO2:Cu devices with Frenkel defect concentration gradients, the vertical Fick force resulting from the concentration gradient can drive mobile oxygen ions to restrain the formation of unrecoverable fragments. Thus, HRS fatigue was improved by restraining the reduction of interfacial barriers. When the gradient becomes large, the bilayer devices demonstrate HRS rise and stuck switching in several switching cycles. In this case, the Fick force may dominate the diffusion of mobile oxygen ions, leading to the overfilling of oxygen vacancies at the interface and an increase in interfacial barriers.

Defect dynamics in the resistive switching characteristics of Y0.95Sr0.05MnO3 films induced by electronic excitations

We understand the role of defect dynamics on the resistive switching (RS) characteristics of pulsed laser deposition (PLD) grown Y0.95Sr0.05MnO3 (YSMO) manganite films on the single crystalline (100) Nb:SrTiO3 (SNTO) substrates (0.2 wt% Nb doped at Ti–site in SrTiO3). The defects were induced in the films by varying the electronic excitations through 200 MeV Ag+15 swift heavy ions (SHI) irradiation with different fluence. The θ–2θ X–ray diffraction (XRD) measurement reveals the single phasic nature of all the films. Epitaxial nature of all pristine and irradiated films has been confirmed through XRD PHI–scan (ϕ–scan) measurement. SHI fluence dependent variations in granular structure and features of the films' surface have been investigated through atomic force microscopy (AFM) measurement. Observed RS behavior has been discussed with LRS to HRS transformation, negative differential resistance (NDR) nature, backward diode character of the junctions and current compliance effect. All these features of the devices have been discussed in the context of trapping–detrapping process and formation–rupture of filamentary conducting paths in the YSMO lattices. Variation in the recorded current values has been understood in terms of alterations in the strain state between the films and substrates and surface properties of the YSMO films. Endurance behavior and retention ability (studied for 50 cycles and up to 300min time duration) of all pristine and irradiated YSMO/SNTO thin film devices suggest an effective reproducibility and reliability for their spintronic based device applications.

Testing Metal–Oxide Varistors for HVDC Breaker Application

There is growing interest in changing the power grid infrastructure. It is increasingly important to transport a large amount of renewable energy over long distances. To minimize losses, meshed dc-grids are needed but require the development of dc circuit breakers. Without it, a meshed grid cannot be operated. Actually different concepts of dc breakers exist. The majority of them include an energy absorbing element. In ac grids, metal-oxide varistors (MOVs) absorb high energies. However, clarification is needed whether commercial available MOVs are able to handle the energy stresses that arise during dc switching operations. To investigate the energy handling capabilities of conventional metal-oxide material, an endurance test setup has been developed. In this setup, MOV specimens are stressed by repetitive impulse current injections while being permanently connected to dc voltage. This study reports on the endurance behavior of MOV submitted to >10 000 impulse energy injections with 60-100 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Large differences are observed for MOVs from different manufacturers. Temperature and superimposing the impulses by a constant dc voltage are two parameters of less impact. Two types of MOV showed moderate changes of their electrical properties after >10 000 impulses and would be suitable for dc breaker application.