Similar Fading Research Articles

Operando X-Ray Analyses of NMC811/Li Batteries: Progress Towards Understanding Capacity Fading Mechanisms at High Voltage and Fast Charge

LiNi0.8Mn0.1Co0.1O2 (NMC811) is a commercially successful Li-ion battery cathode due to its high energy density and cyclability. Utilizing this system under fast charge and high potential charge conditions is of great interest as this will help facilitate widespread electric vehicle adoption; however, these aggressive charging conditions lead to enhanced capacity fade. To design next-generation NMC811 batteries with longer life and higher capacity the origins of the capacity fade must be understood. Operando X-ray characterization techniques are critical for this endeavor as they allow the acquisition of information about the evolution of structure, oxidation state, and coordination environment as the material (de)lithiates in a functional battery. Charging to high potential (4.7 V) leads to greater delivered initial capacity but much more significant fading; while fast charging (4C) leads to slightly reduced capacity but with similar fading. Operando XRD and SEM results indicated that secondary particle fracture from increased structural distortions at >4.3 V was a contributor to capacity fade. On the other hand, fast charging led to a slight reduction in structural distortions consistent with the reduced capacity fade. Operando hard XAS revealed significant Ni and Co redox during cycling as well as a Jahn-Teller distortion at the discharged state (Ni3+). Greater bulk redox was observed when charged to 4.7 V while less bulk redox was observed at 4C, consistent with the different delivered capacities. Soft XAS analyses revealed significant surface reconstruction after cycling to 4.7 V. Overall, charging to 4.7 V leads to more structural distortions and particle fracture, as well as surface reconstruction that lead to increased capacity fading. Fast charge does not induce additional structural distortion or surface reconstruction as compared to the slower, moderate charging potential cycling suggesting that the phenomena at the anode may be more critical under fast charge.

IRAS 00450+7401 and the Mid-infrared Fade/Burst Cycle of R Coronae Borealis-type Stars

We present optical and infrared imaging and spectroscopy of the R Coronae Borealis-type (R Cor Bor) star IRAS 00450+7401. Optical spectra further confirm its classification as a cool R Cor Bor system, having a hydrogen-deficient carbon star spectral subclass of HdC5 or later. Mid-infrared spectroscopy reveals the typical ∼8 μm “hump” seen in other R Cor Bor stars and no other features. A modern-epoch spectral energy distribution shows bright emission from hot dust having T dust > 600 K. Historical infrared data reveal generally cooler dust color temperatures combined with long-term fading trends, but provide no discernible correlation between flux level and temperature. Investigating the most mid-infrared variable R Cor Bor stars found in IRAS, AKARI, and WISE data reveals similar fading trends, bursts that can show a factor of up to 10 change in flux density between epochs, and blackbody-fit dust color temperatures that span 400–1300 K. While some R Cor Bor stars such as IRAS 00450+7401 appear to undergo fade/burst cycles in the mid-infrared, significant gaps in temporal coverage prevent conclusively identifying any preferred timescale for their mid-infrared variability and circumstellar dust temperature changes.

Host galaxy magnitude of OJ 287 from its colours at minimum light

ABSTRACTOJ 287 is a BL Lacertae type quasar in which the active galactic nucleus (AGN) outshines the host galaxy by an order of magnitude. The only exception to this may be at minimum light when the AGN activity is so low that the host galaxy may make quite a considerable contribution to the photometric intensity of the source. Such a dip or a fade in the intensity of OJ 287 occurred in 2017 November, when its brightness was about 1.75 mag lower than the recent mean level. We compare the observations of this fade with similar fades in OJ 287 observed earlier in 1989, 1999, and 2010. It appears that there is a relatively strong reddening of the B− V colours of OJ 287 when its V-band brightness drops below magnitude 17. Similar changes are also seen in V− R, V− I, and R− I colours during these deep fades. These data support the conclusion that the total magnitude of the host galaxy is V = 18.0 ± 0.3, corresponding to MK = −26.5 ± 0.3 in the K-band. This is in agreement with the results, obtained using the integrated surface brightness method, from recent surface photometry of the host. These results should encourage us to use the colour separation method also in other host galaxies with strongly variable AGN. In the case of OJ 287, both the host galaxy and its central black hole are among the biggest known, and its position in the black hole mass–galaxy mass diagram lies close to the mean correlation.

Inducing bract-like leaves in Arabidopsis through ectopically expressing an ASR gene from the dove tree

Bract, or inflorescence leaf, is cryptic in most model plants due to a conserved suppression mechanism. While, bract is present in some ornamental plants and plays an important role in their reproductive growth. The huge and long-standing bract of an ancient species, the dove tree (Davidia), implies the existence of a distinctive pathway of bract development. However, compared to bract suppression, little is known about the regulators during bract promoting. Here, a gene named DiASR1 involved into bract development regulation in Davidia is reported. During bract development, the expression profile of the DiASR1 gene was bract-specific, and increased along with the bract growth. The DiASR1 gene was activated by environmental cues including high temperature, strong light and abscisic acid, while inhibited by low temperature, dark, gibberellin. Remarkably, ectopic expression of the DiASR1 gene resulted in bract-like leaves, besides early flowering, abnormal floral development, and aborted pollens in transgenic Arabidopsis lines. The bract-like Arabidopsis leaves exhibited a similar fading process and cell architecture to those of Davidia bract. The ectopic induction of bract-like leaves confirmed the critical function of the DiASR1 gene for bract development, and provided new insights to understand the regulation mechanism underlying the process of leaf metamorphosis.

The role of the pH value in water-based pastes on the processing and performance of Ni-rich LiNi0.5Mn0.3Co0.2O2 based positive electrodes

The influence of the preset pH value of the binder solution on aqueous processing of LiNi0.5Mn0.3Co0.2O2 positive electrodes is studied. The processed electrodes are investigated by means of electrochemical charge/discharge cycling, potentiostatic electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results show major impact of the pH value of the binder solution on the cycling performance of lithium ion cells. Low binder solution pH values (here 7.6) lead to faster capacity fading within the first 100 cycles. In comparison, higher binder solution pH values (here 12.5) show similar fading compared to the reference electrodes based on poly(vinylidene difluoride) and N-methyl pyrrolidone as solvent. Positive electrode materials undergo a lithium-proton exchange, when in contact with water or other proton sources. Post-mortem analysis revealed that lower pH values of the binder solution potentially lead to more pronounced lithium-proton exchange. The previously inserted protons are extracted from the active material during electrochemical cycling, potentially initiate decomposition of the conductive salt LiPF6 and hence degrade the cell performance.In combination with LiPF6, inter alia HF might be formed, which then reacts with lithium from LiNi0.5Mn0.3Co0.2O2 or other active and inactive components and precipitate as M-F or other resistive interphases on the LiNi0.5Mn0.3Co0.2O2 surface.

Delta plots with negative-going slopes as a potential marker of decreasing response activation in masked semantic priming.

Delta plots with negative-going slopes (nDPs) reflect the phenomenon that an RT difference between two conditions is greater for relatively fast than for relatively slow responses. This unusual distributional pattern has predominantly been observed in the spatial Simon task, where it has been interpreted as reflecting the selective inhibition of an automatically activated response. The literature suggesting that a similar fading mechanism influences RTs in masked identity priming inspired us to check an analogous semantic priming paradigm for nDPs. Consistent with the findings in other paradigms, two masked semantic priming experiments revealed stronger priming effects for relatively fast than for relatively slow responses, thus reflecting an nDP. These findings are compatible with the ideas that the activation produced by masked semantic primes decreases over the course of a trial, such as that of irrelevant spatial information and of masked identity primes, and that nDPs are a general signature of within-trial decreases in response activation across different tasks and paradigms.

Storage Fading Mechanism of a Commercial 18650 Cell Comprised with Composite NMC/LMO Cathode and Graphite Anode

In this study, the capacities and electrochemical impedances at various states of charge (SOC) are measured after the screened commercial 18650 lithium ion cells assembled with composite cathode of layered mixed oxide (NMC) and spinel lithium manganite (LMO) and graphite anode were stored at various states of depth-of-discharge (DOD) at various temperatures for various durations. The results manifest that the capacity fading is strongly affected by the storage temperature and becomes prominent at temperatures higher than 45oC. Incremental capacity analyses (ICA) for the charge/discharge curves before and after storage were performed for the qualitative mechanism study. It demonstrates that the capacity fade of the cell stored at 60oC and 0% DOD can be attributed to the loss of active materials, and the loss of graphite anode is higher than that of composite cathode. The capacity fade of the cell stored at 60oC and 25% DOD can be caused by the lithium inventory loss, the loss of NMC, and the loss due to the morphology change of LMO. Cell stored at 50% DOD manifests similar fading behavior as that of the cell stored at 0% DOD, however, the ICA plots demonstrate that the capacity loss of the cell comes from losses of lithium inventory and NMC caused by the dissolution of transition metals with additional losses of LMO and graphite anode occur after 10 months of accumulated storage. For cell stored at 75% DOD, most the capacity loss can be due to the loss of NMC with minor contribution of lithium inventory loss, while cell stored at 100% DOD shows almost no change after storage for 12 accumulated months. These results revealed from the ICA study are consistent with those determined from the post mortem study of the electrodes obtained from cells before and after storage.

Another deep dimming of the classical T Tauri star RW Aurigae A

Context. RW Aur A is a classical T Tauri star (CTTS) with an unusually rich emission line spectrum. In 2014 the star faded by ~ 3 magnitudes in the V band and went into a long-lasting minimum. In 2010 the star suffered from a similar fading, although less deep. These events in RW Aur A are very unusual among the CTTS, and have been attributed to occultations by passing dust clouds. Aims. We want to find out if any spectral changes took place after the last fading of RW Aur A with the intention to gather more information on the occulting body and the cause of the phenomenon. Methods. We collected spectra of the two components of RW Aur. Photometry was made before and during the minimum. Results. The overall spectral signatures reflecting emission from accretion flows from disk to star did not change after the fading. However, blue-shifted absorption components related to the stellar wind had increased in strength in certain resonance lines, and the profiles and strengths, but not fluxes, of forbidden lines had become drastically different. Conclusions. The extinction through the obscuring cloud is grey indicating the presence of large dust grains. At the same time, there are no traces of related absorbing gas. The cloud occults the star and the interior part of the stellar wind, but not the wind/jet further out. The dimming in 2014 was not accompanied by changes in the accretion flows at the stellar surface. There is evidence that the structure and velocity pattern of the stellar wind did change significantly. The dimmings could be related to passing condensations in a tidally disrupted disk, as proposed earlier, but we also speculate that large dust grains have been stirred up from the inclined disk into the line-of-sight through the interaction with an enhanced wind.

Patterns of GRP78 and MTJ1 expression in primary cutaneous malignant melanoma

Cell surface expression of glucose-regulated protein 78 (GRP78) occurs in several types of cancer; however, its role in the behavior of primary cutaneous melanoma is not well studied. The association of cell surface GRP78 with other proteins such as MTJ1 stimulates cell proliferation. In this study, we characterized the pattern of expression of GRP78 and MTJ1 in invasive primary cutaneous melanomas and analyzed the relationships between the pattern of expression and various clinicopathological parameters. We found two patterns of GRP78 expression in invasive primary cutaneous melanoma. One pattern showed a gradual fading of protein expression from superficial to deeper levels within the same tumor. The second pattern of expression showed a similar fading with an abrupt regaining of expression at the deep invasive edge of the melanoma. These two distinct patterns of GRP78 expression correlated with both patient survival and depth of tumor invasion. A moderate MTJ1 expression was found to be associated with decreased patient survival; however, no significant associations were observed between patterns of GRP78 and MTJ1 expression. Our study (1) describes two distinct patterns of GRP78 in invasive primary cutaneous melanoma, (2) inversely correlates regain of GRP78 expression with patient survival, and (3) suggests a modifying effect of MTJ1 on GRP78 in enhancing tumor aggressiveness.

On the Fading-Paper Achievable Region of the Fading MIMO Broadcast Channel

We consider transmission over the ergodic multiple-antenna broadcast (MIMO-BC) channel with partial channel state information at the transmitter and full information at the receiver. Over the equivalent non-fading channel, capacity has recently been shown to be achievable using transmission schemes that were designed for the channel. We focus on a similar fading model. The evaluation of the paper capacity is difficult to obtain. We confine ourselves to the linear-assignment capacity, which we define, and use convex analysis methods to prove that its maximizing distribution is Gaussian. We compare our fading-paper transmission to an application of dirty paper coding that ignores the partial state information and assumes the channel is fixed at the average fade. We show that a gain is easily achieved by appropriately exploiting the information. We also consider a cooperative upper bound on the sum-rate capacity as suggested by Sato. We present a numeric example that indicates that our scheme is capable of realizing much of this upper bound.

The relationship between twitch depression and twitch fade during neuromuscular block produced by vecuronium: correlation with the release of acetylcholine

BackgroundTrain-of-four stimulation pattern following the administration of non-depolarizing neuromuscular blocking drugs reveals fade on successive contractions. Fade is caused by the release of fewer acetylcholine molecules by the fourth (A4) than by the first stimulus (A1). The current study was conducted to define the relationship between the clinically observed fade and the simulated decline in acetylcholine release (A4/A1) that would be necessary to produce it.MethodsThe T4/T1 ratios produced by different doses of vecuronium (15–80 μg·kg-1) were plotted as a function of the concomitant T1. Separately in a model of neuromuscular transmission, T1, T4, and T4/T1 were estimated using simulations in the presence and in the absence of a neuromuscular blocking drug and a stepwise decrease in A4, but constant A1.ResultsVecuronium induced neuromuscular block was associated with larger T4/T1 ratios (less fade) during the onset than during the offset of the block. All doses caused similar fade during offset. Simulations revealed that the smallest T4/T1 was associated with the nadir of A4/A1 and occurred at the beginning of T1 recovery. The nadir of A4/A1 was only marginally affected by the dose of vecuronium: 15 μg·kg-1 producing the minimum A4/A1 of 0.8 and 80 μg·kg-1 the minimum A4/A1 of 0.7.ConclusionThe hysteresis in the fade between onset and offset appears to be caused by a delayed decrease of A4/A1 as compared with the decrease in T1. Tentative estimates of the decrease in A4/A1 during fade produced by vecuronium are offered. However, the validity of these estimates is dependent on the validity of the assumptions made in simulations.

Auroral fading structure before breakup: A review

This review is devoted to auroral fading before beginning of the substorm active phase. This initial stage of the active phase called breakup is accompanied by a sharp brightening of auroras and their rush toward the pole. Auroral fading before breakup was first detected in discrete auroras in the nightside sector and consisted in that a short-term decrease in brightness of an arc moving toward the equator below the level observed during the preliminary phase was observed during the substorm preliminary phase 2–3 min before breakup. During fading, the velocity of equatorward motion of auroral arcs decreased up to their complete stoppage. Auroral fading in the noon sector was registered simultaneously with fading on the Earth’s nightside before the beginning of the active phase. Short-term background fading was also observed both equatorward and poleward of an arc on the nightside. It was subsequently indicated that similar fading is observed in various geophysical phenomena. It was detected that a radar aurora signal fades before breakup, if auroral substorm is observed in a radar pattern and substorm source is located under good aspect conditions. Riometer absorption decreases simultaneously with auroral fading. Geomagnetic pulsations decay on dayside and nightside immediately before breakup. Such a multiform manifestation of fading in various geophysical phenomena indicates that fading is related to some global processes proceeding in the magnetosphere when energy accumulation in this region comes to the end before its explosive release into the polar ionosphere.

Degree of polarization technique used in PMD compensation of optical microwave transmission systems

Polarization-mode dispersion (PMD) can severely degrade the performance of optical microwave transmission systems by inducing a periodic power fading of the received RF signal that depends on the subcarrier frequency and accumulated differential group delay (DGD) along fiber. We derive a compact analytical expression of the degree of polarization (DOP) of optical signal using Jones and Stokes representations based on first-order assumption. Using this expression, we quantify the signal DOP fading induced by PMD by means of numerical simulations for BPSK and ASK modulations. The dependences of signal DOP on subcarrier frequency, accumulated DGD, and modulation formats have been demonstrated. It is found that signal DOP has similar periodic fading with the power of received RF signal, which is caused by DGD. Moreover, if the DOP technique is used in the PMD compensation of the optical microwave transmission systems, the DOP degradation is more sensitive to the DGD in the system modulated by BPSK than by ASK. The performance of this technique is immune to residual chromatic dispersion of the fiber.

Time-locked Perceptual Fading Induced by Visual Transients

After prolonged fixation, a stationary object placed in the peripheral visual field fades and disappears from our visual awareness, especially at low luminance contrast (the Troxler effect). Here, we report that similar fading can be triggered by visual transients, such as additional visual stimuli flashed near the object, apparent motion, or a brief removal of the object itself (blinking). The fading occurs even without prolonged adaptation and is time-locked to the presentation of the visual transients. Experiments show that the effect of a flashed object decreased monotonically as a function of the distance from the target object. Consistent with this result, when apparent motion, consisting of a sequence of flashes was presented between stationary disks, these target disks perceptually disappeared as if erased by the moving object. Blinking the target disk, instead of flashing an additional visual object, turned out to be sufficient to induce the fading. The effect of blinking peaked around a blink duration of 80 msec. Our findings reveal a unique mechanism that controls the visibility of visual objects in a spatially selective and time-locked manner in response to transient visual inputs. Possible mechanisms underlying this phenomenon will be discussed.

Time-locked Perceptual Fading Induced by Visual Transients

Abstract After prolonged fixation, a stationary object placed in the peripheral visual field fades and disappears from our visual awareness, especially at low luminance contrast (the Troxler effect). Here, we report that similar fading can be triggered by visual transients, such as additional visual stimuli flashed near the object, apparent motion, or a brief removal of the object itself (blinking). The fading occurs even without prolonged adaptation and is time-locked to the presentation of the visual transients. Experiments show that the effect of a flashed object decreased monotonically as a function of the distance from the target object. Consistent with this result, when apparent motion, consisting of a sequence of flashes was presented between stationary disks, these target disks perceptually disappeared as if erased by the moving object. Blinking the target disk, instead of flashing an additional visual object, turned out to be sufficient to induce the fading. The effect of blinking peaked around a blink duration of 80 msec. Our findings reveal a unique mechanism that controls the visibility of visual objects in a spatially selective and time-locked manner in response to transient visual inputs. Possible mechanisms underlying this phenomenon will be discussed.

The effects of heat-treatment temperature on the retention capacities of spinels prepared by the Pechini process

Stoichiometric LiMn 2O 4 was prepared by the Pechini method and heat-treated at temperatures between 600 and 800 °C for 8 h. Crystalline structures and the electrochemical properties of the prepared samples were investigated. The sample heat-treated at 600 °C shows a trace amount of Mn 2O 3 with predominant spinel, whereas those prepared at temperatures between 700 and 800 °C show exclusively spinel with similar lattice constants. The crystallinity index calculated from the (1 1 1) peak of XRD pattern increases with increasing heat-treatment temperature. All of the prepared samples show similar capacity fading rate. On the same cycle number, the specific capacity increases with increasing temperature of heat-treatment. It is found that samples with similar lattice constant exhibit similar specific discharging capacity on the same cycle number and similar fading rate at the high voltage plateau. The crystallinity index and the initial specific discharge capacity on the low-voltage plateau increase with increasing heat-treatment temperature.

Photochromic Properties of New Benzoindene‐Fused 2H‐Chromenes

AbstractThe synthesis and the photochromic properties of new photochromic 6,7‐ and 7,8‐benzoindene annellated benzopyrans are described. When compared to parent indeno‐fused 2H‐chromenes (2H‐[1]benzopyrans), compounds 10 and 12 exhibit a significant bathochromic shift of maximum‐absorption wavelength, an increase in the colorability, and similar fading rates.

Ionospheric drift measurements with ionosondes

In the last forty years many attempts have been made to measure ionospheric plasma motions with HF radio sounders, generally specialized ionosondes. Starting in the 1950's, the so-called similar fading and the correlation methods were applied to estimate the velocities in the ionosphere. More recently, the interferometric Doppler technique was introduced which successfully measured ionospheric drifts that were verified by incoherent scatter radar measurements. The latter technique is discussed in some detail in this paper.

Prediction of Petrophysical Parameters Based on Digital Video Core Images

Summary Core-slab photography is a common way to document geological information from cores. Past practice has been to photograph core slabs with ordinary cameras that produce paper photographs. The presented method retrieves petrophysical properties from high-resolution digital video core images. The procedures described in this work are based on video images (standard RIO/B camera) of cores taken with a digital recording system. The system is able to record in both visible and UV light at different illumination angles, store images, compress/decompress images, and display one or several images as a continuous long core. The seamless core image is marked with depth scale and can be scrolled, scaled, and zoomed. Facilities for correlation with other related data, such as wireline logs, discrete core data, and microscopy images, are also included in the system. We used homogenous dry core plugs from three North Sea oil fields in this work. We recorded images of plug surface, together with conventional core-analysis data (i.e., porosity, gas permeability, average grain size, and mineralogy). The new method is based on processed digital images: light/shadow patterns are obtained by use of asymmetric, low-angle illumination in the green channel. Texture spectra of the rock material are obtained by dedicated image-analytical processing of these gray-scale images and by detecting textural features by use of a unique set of specially designed texture filters. We then calibrate these spectra with respect to measured petrophysical parameters by use of multivariate calibration [partial least squares (PLS)-regression]. Multivariate calibration is based on a set of representative training images, selected to span representative ranges of the intensive petrophysical parameters being modeled. On the basis of this calibration model, similar gray-level video images from new, unknown core sections (with geologically similar fades) are used to estimate properties of the core material by PLS-prediction. In this study it has been possible to model porosity, gas permeability, and average grain size (ORZ) of different formations with a relatively high accuracy and precision. PLS-modeling/-prediction is a strict empirical calibration procedure. The present method is critically dependent upon a thorough, geologically well-documented training data set. Results show that the method is capable of predicting a continuous log of these three petro-physical parameters based on core images calibrated against a set of routine laboratory core-analysis data taken at discrete intervals for a particular formation. The advantages of the new method are rapid and cost-efficient methods for prediction of petrophysical parameters, particularly from slim cores, and improved integration of geological records with wireline data. The method is proposed to be included in future routine laboratory core analysis studies because of its low cost and ability to predict values continuously along the core.

Estimation of potential photochemical properties for monochlorotriazinyl reactive dyes and their manifestations in the fading of dyed cellulose

Cellulose films dyed with 10 monochlorotriazinyl reactive dyes were exposed to light in various aqueous solutions and the following potential photochemical reactivities of dyes estimated: (i) ease with which the dyes are photo-oxidized, (ii) ease with which dyes are photo-reduced, (iii) apparent photosensitivity, and (iv) the rates of fading in aerated water. On irradiating the dry reactive cotton dyeings, fading proceeded in two steps, viz. many dyes exhibited a considerable initial fading, accompanied by slow subsequent fading. On exposing the dry dyed cellulose films, little initial fading was observed. The fading behavior of some dyes could be explained by their potential properties, while other dyes underwent slow fading, probably due to a compensation between oxidative and reductive photofading processes even though the dyes had high photoreactivity. The concentration dependence on the fading behavior of dyed films could be explained by the filter effect with some exceptions, where dyes with high photosensitivity showed larger or similar fading in deep dyeings than that in the paler dyeings.