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- 2017
- spectral reconstruction
- interference
- polarization
- transform
- imaging spectrometer
- Optoelectronic Information Science and Engineering
- BITTT
- Zhejiang University
- Guilin University of Aerospace Technology
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Fabrication of Stable Carbon Nanotube Cold Cathode Electron Emitters with Post-Growth Electrical Aging
摘要： We fabricated carbon nanotube (CNT) cold cathode emitters with enhanced and stable electron emission properties and long-time stability with electrical aging as a post-treatment. Our CNT field emitters showed improved electrical properties by electrical aging. We set the applied bias for effective electrical aging, with the bias voltage defined at the voltage where Joule heating appeared. At the initial stage of aging, the electron emission current started to increase and then was saturated within 3 h. We understood that 5 h aging time was enough at proper aging bias. If the aging bias is higher, excessive heating damages CNT emitters. With the electrical aging, we obtained improved electron emission current from 3 mA to 6 mA. The current of 6 mA was steadily driven for 9 h.
关键词： carbon nanotube,electrical aging,electron emission,Joule heating,field emitters
更新于2025-09-23 15:23:52
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Identification of Maize Kernel Vigor under Different Accelerated Aging Times Using Hyperspectral Imaging
摘要： Seed aging during storage is irreversible, and a rapid, accurate detection method for seed vigor detection during seed aging is of great importance for seed companies and farmers. In this study, an artificial accelerated aging treatment was used to simulate the maize kernel aging process, and hyperspectral imaging at the spectral range of 874–1734 nm was applied as a rapid and accurate technique to identify seed vigor under different accelerated aging time regimes. Hyperspectral images of two varieties of maize processed with eight different aging duration times (0, 12, 24, 36, 48, 72, 96 and 120 h) were acquired. Principal component analysis (PCA) was used to conduct a qualitative analysis on maize kernels under different accelerated aging time conditions. Second-order derivatization was applied to select characteristic wavelengths. Classification models (support vector machine?SVM) based on full spectra and optimal wavelengths were built. The results showed that misclassification in unprocessed maize kernels was rare, while some misclassification occurred in maize kernels after the short aging times of 12 and 24 h. On the whole, classification accuracies of maize kernels after relatively short aging times (0, 12 and 24 h) were higher, ranging from 61% to 100%. Maize kernels with longer aging time (36, 48, 72, 96, 120 h) had lower classification accuracies. According to the results of confusion matrixes of SVM models, the eight categories of each maize variety could be divided into three groups: Group 1 (0 h), Group 2 (12 and 24 h) and Group 3 (36, 48, 72, 96, 120 h). Maize kernels from different categories within one group were more likely to be misclassified with each other, and maize kernels within different groups had fewer misclassified samples. Germination test was conducted to verify the classification models, the results showed that the significant differences of maize kernel vigor revealed by standard germination tests generally matched with the classification accuracies of the SVM models. Hyperspectral imaging analysis for two varieties of maize kernels showed similar results, indicating the possibility of using hyperspectral imaging technique combined with chemometric methods to evaluate seed vigor and seed aging degree.
关键词： hyperspectral imaging technology,standard germination tests,support vector machine model,accelerated aging,principal component analysis,maize kernel
更新于2025-09-23 15:22:29
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Effects of temporary fogging and defogging in plastic scintillators
摘要： Recent studies have shown that under certain environmental conditions, plastic scintillators which are used in a variety of applications in outdoor environments develop defects called "fogging", resulting in a reduced useful lifetime and increased maintenance cost. Applications of plastic scintillators include scanning recycled steel going into a processing plant, personnel portals to scan employees, and scanning cargo and cars crossing borders of many countries. In this report, fogging was studied in conventional PVT and PS-based plastic scintillators, both field aged and freshly cast. A new fogging-resistant PVT-based formulation developed by scientists at Lawrence Livermore National Laboratory (LLNL) was tested as well. We used accelerated aging experiments via temperature and humidity cycling in controlled laboratory conditions to create observable temporary fogging defects in small samples (≤1 in3). Photoluminescence and optical transmission studies were used to evaluate the effect of the fogging. The time evolution of the induced temporary fogging formation and defogging (i.e. fading of defects in ambient conditions over time) were recorded using optical microscopy, time-lapse photography, and gravimetric analysis.
关键词： Accelerated aging,Optical microscopy,Scintillator,Gamma detection
更新于2025-09-23 15:22:29
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Fabrication of stable carbon nanotube cold cathode electron emitters with electrical aging
摘要： We studied on the fabrication and improved field emission properties of carbon nanotube (CNT) cold cathode electron emitters with electrical aging. Our CNT field emitters have improved electron emission properties with thermal and electrical aging. For the set-up of electrical aging, we used bias voltage at Joule heating appeared. Our CNT emitters show increases of electron emission at initial stage of aging and then saturation of emission current. With the electrical aging, we obtained enhanced electron emission from 3 mA to 5.5 mA and long- time stable operation.
关键词： Field emission,Carbon nanotubes,Electrical aging,Annealing
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE SENSORS - Montreal, QC, Canada (2019.10.27-2019.10.30)] 2019 IEEE SENSORS - Optical sensor based on pseudo-random diffractive optical elements for reliable gesture reconstruction
摘要： Biometric template aging is defined as an increase in recognition error rate with increased time since enrollment. It is believed that template aging does not occur for iris recognition. Several research groups, however, have recently reported experimental results showing that iris template aging does occur. This template aging effect manifests as a shift in the authentic distribution, resulting in an increased false non-match rate. Analyzing results from a three-year time-lapse data set, we find ～ 150% increase in the false non-match rate at a decision threshold representing a one in two million false match rate. We summarize several known elements of eye aging that could contribute to template aging, including age-related change in pupil dilation. Finally, we discuss various steps that can control the template aging effect in typical identity verification applications.
关键词： false non-match rate,iris recognition,Biometrics,error probability,template aging
更新于2025-09-23 15:21:01
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Effect of Precursor Aging on Builta??In Potential in Formamidiniuma??Based Perovskite Solar Cells
摘要： Formamidinium-based perovskite with optimal bandgap and improved thermal stability is a promising active material for application in perovskite solar cells (PSCs). The hybrid precursor solutions, formed by adding various smaller cations, are often used for improving the phase stability in PSCs. In this work, we report the effort on understanding the aging effect of a methylammonium- and bromine-free formamidinium precursor solution on the performance of FA0.85Cs0.1Rb0.05PbI3-based PSCs. Our results reveal that deterioration in the built-in potential in the PSCs is closely associated with the formation of the secondary phase in the FA0.85Cs0.1Rb0.05PbI3 active layer. The formation of the secondary phase in the active layer is related to the hydrolysis of the precursor solution. The suppression of the moisture encroachment greatly enhances the durability of the precursor solution and performance reproducibility of the PSCs.
关键词： precursor solution aging,perovskite solar cell,secondary phase,built-in potential
更新于2025-09-23 15:21:01
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Ferroelectric Materials - Synthesis and Characterization || Biasing Effects in Ferroic Materials
摘要： In this chapter we present an overview of some important concepts related to the processes and microstructural mechanisms that produce the deformation of hysteresis loops and the loss of their symmetry characteristics in ferroelectric, ferroelastic and ferromagnetic systems. The most discussed themes include: aging and fatigue as primary mechanisms of biased hysteresis loops in ferroelectric/ferroelastic materials, imprint phenomenon as an important biasing process in ferroelectric thin films, the development of an exchange bias field and of specific spin states, such as spin canting and spin-glass-like phases, as the main causes of biased hysteresis loops in different types of magnetic heterostructures. The present discussion leads to the identification of the main differences and possible analogies in the underlying mechanisms of possible biasing effects occurring in the different ferroic systems, which can benefit the theoretical description, modelling, and engineering of multifunctional devices based on ferroic systems experiencing the internal bias phenomena.
关键词： Aging,exchange bias,internal field,fatigue,imprint
更新于2025-09-23 15:21:01
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Low-Temperature Aging Provides 22% Efficient Bromine-Free and Passivation Layer-Free Planar Perovskite Solar Cells
摘要： Previous reports of formamidinium/methylamine (FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface—for example, through the inclusion of bromine and surface passivation. In this paper, we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI3 halide perovskites via the control of intermediate phase. Through low-temperature aging growth (LTAG) of a freshly deposited perovskite film, α-phase perovskites can be seeded in the intermediate phase and, at the same time, prevent beta-phase perovskite to nucleate. After postannealing, large grain-size perovskites with significantly reduced PbI2 presence on the surface can be obtained, thereby eliminating the need of additional surface passivation step. Our pristine LTAG-treated solar cells could provide PCEs of greater than 22% without elaborate use of bromine or an additional passivation layer. More importantly, when using this LTAG process, the growth of the pure alpha-phase FAMAPbI3 was highly reproducible.
关键词： Perovskite solar cells,Bromine-free,Passivation layer,Lead iodide,Aging growth
更新于2025-09-23 15:21:01
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The use of Carboxytherapy alone or in combination with fractional CO2 laser for facial rejuvenation: A splita??face comparative study
摘要： Background A wide variety of minimally invasive treatments are available for skin aging. Recently carbon dioxide therapy (CDT) or carboxytherapy was used in many cosmetic indications including facial rejuvenation. Objective To compare the efficacy of CDT alone versus combined CDT and fractional CO2 laser in management of facial aging. Methods Twenty-Five female patients with bilateral and symmetrical facial aging were included in the study. The right (Rt) hemiface received 8 sessions of CDT whereas the left (Lt) side was treated with combined technique (6 sessions of CDT and 2 sessions of fractional CO2 in between. Clinical and objective evaluation using 3D skin analysis, histological and morphometric analysis were performed. Results Clinical evaluation demonstrated that all patients (100%) were satisfied with no significant difference between both sides of the face (p>0.05). Regarding texture and pigmentation improvement, the Lt side (combined) showed significant improvement compared to the Rt side (p<0.05). Using Antera 3D camera, there was a significant difference (p<0.05) in 3D improvement percent in textural changes while there was no significant difference (p>0.05) in the 3D percent of wrinkles improvement between both sides. The Lt. side showed more significant increase in epidermal thickness after treatment when compared to the Rt. side (p<0.05) with evident neocollagen formation. Conclusion Carboxytherapy is an easy, safe, simple and a relatively effective method for facial rejuvenation with minimal downtime. Better results were achieved when used in combination with fractional CO2 laser.
关键词： skin aging,minimally invasive treatments,fractional CO2 laser,facial rejuvenation,Carboxytherapy
更新于2025-09-23 15:21:01
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A Protocol for Transcranial Photobiomodulation Therapy in Mice
摘要： Transcranial photobiomodulation is a potential innovative noninvasive therapeutic approach for improving brain bioenergetics, brain function in a wide range of neurological and psychiatric disorders, and memory enhancement in age-related cognitive decline and neurodegenerative diseases. We describe a laboratory protocol for transcranial photobiomodulation therapy (PBMT) in mice. Aged BALB/c mice (18 months old) are treated with a 660 nm laser transcranially, once daily for 2 weeks. Laser transmittance data shows that approximately 1% of the incident red light on the scalp reaches a 1 mm depth from the cortical surface, penetrating the dorsal hippocampus. Treatment outcomes are assessed by two methods: a Barnes maze test, which is a hippocampus-dependent spatial learning and memory task evaluation, and measuring hippocampal ATP levels, which is used as a bioenergetics index. The results from the Barnes task show an enhancement of the spatial memory in laser-treated aged mice when compared with age-matched controls. Biochemical analysis after laser treatment indicates increased hippocampal ATP levels. We postulate that the enhancement of memory performance is potentially due to an improvement in hippocampal energy metabolism induced by the red laser treatment. The observations in mice could be extended to other animal models since this protocol could potentially be adapted to other species frequently used in translational neuroscience, such as rabbit, cat, dog, or monkey. Transcranial photobiomodulation is a safe and cost-effective modality which may be a promising therapeutic approach in age-related cognitive impairment.
关键词： low-level laser therapy,optical properties,red light,hippocampus,mouse,aging,Transcranial photobiomodulation,learning,memory,Issue 141,Neuroscience
更新于2025-09-23 15:21:01