scholarly journals Study of Cu Electrochemical Polishing Mechanism With Observation of Water Acceptor Diffusion

2021 ◽  
Vol 9 ◽  
Author(s):  
Kimoon Park ◽  
Jinhyun Lee ◽  
Youjung Kim ◽  
Sangwha Yoon ◽  
Bongyoung Yoo
Keyword(s):  
Electrochemical Impedance ◽  
Low Frequency ◽  
Electrochemical Analysis ◽  
Electrochemical Polishing ◽  
Salt Film ◽  
System A ◽  
Long Time ◽  
Cu Dissolution ◽  
First Time ◽  
Electrochemical Microscopy

The salt-film and water acceptor mechanisms were generally accepted mechanisms for Cu electrochemical polishing (ECP) theory. These mechanisms of Cu ECP are still controversial for a long time. Conventional and new electrochemical analysis methods were used to investigate the mechanisms and behaviors of Cu electrochemical polishing. Two cases of Cu dissolution, with and without polishing, were classified by results of linear scan voltammetry (LSV) and scanning electron microscopy (SEM). The electrochemical impedance spectroscopy (EIS) results showed the main difference in these two cases was in the low-frequency region. However, it was hard to distinguish between the salt-film and water acceptor mechanisms by conventional electrochemical analysis. A scanning electrochemical microscopy (SECM) system, a new electrochemical analysis method that measures the electrolysis currents of the water acceptors along with a set distance from the substrate, was used to investigate the Cu ECP mechanism. Accordingly, the diffusion of the water acceptors was successfully confirmed for the first time. Finally, the mechanisms of the Cu ECP are definitively described by using all analysis results.

scholarly journals Electrochemical Impedance of Hydrogenated Phases of ZnO and CuO Nanoparticles for Electrode Applications

2020 ◽  
pp. 1-6
Author(s):  
L. I. Menegbo ◽  
J. L. Konne ◽  
N. Boisa
Keyword(s):  
Electrochemical Impedance ◽  
Sol Gel ◽  
Low Frequency ◽  
High Gain ◽  
High Frequency Region ◽  
Nyquist Plots ◽  
Eis Measurements ◽  
Xrd Patterns ◽  
Straight Lines ◽  
First Time

The Electrochemical Impedance Spectroscopy (EIS) measurements of Sol-gel synthesized ZnO, CuO and their respective hydrogenated phases (ZnO:H and CuO:H) for  a proton-type battery model has been reported for the first time. The XRD patterns confirmed that CuO and ZnO were phase pure with minor impurities. However, that of CuO:H showed mixed phases of CuO and Cu2O with the later  appearing prominent. The estimated particle sizes of ZnO, ZnO:H, CuO and CuO:H obtained using Scherrers’ equation were 17.83, 17.75, 21.63 and 15.42 nm respectively, showing remarkable particle size reductions upon hydrogenation as oxygen vacancies were substituted with smaller hydrogen ions. Nyquist plots from the EIS experimental data recorded over a frequency range of 100 kHz – 5 mHz showed expected flat semicircles at the high frequency region and straight lines at the low frequency regions while resistance estimations from the intercepts of the Bode plots were 12.10, 7.80, 16.00 and 10.80 Ω for ZnO, ZnO:H, CuO and CuO:H respectively. It also indicated high gain margins suggesting impressive electrochemical properties for battery applications.

Direct imaging of charge transfer

1996 ◽  
Vol 54 ◽  
pp. 680-681
Author(s):  
Yimei Zhu ◽  
J. Tafto
Keyword(s):  
Charge Transfer ◽  
Electron Diffraction ◽  
Scattering Amplitude ◽  
High Temperature Superconductors ◽  
Charge Carriers ◽  
Image Charge ◽  
Net Charge ◽  
Long Time ◽  
Electron Holes ◽  
First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

Assessment of recreational use of specially protected natural territories of Tatishchevsky district of Saratov region

2019 ◽  
Vol 27 (2) ◽  
pp. 117-127
Author(s):  
Yulia M Andriyanova ◽  
Irina V Sergeeva ◽  
Yulia M Mokhonko ◽  
Natalia N Gusakova
Keyword(s):  
Natural Resources ◽  
Protected Areas ◽  
Saratov Region ◽  
Future State ◽  
Forest Phytocenoses ◽  
Long Time ◽  
Main Components ◽  
First Time ◽  
Recreational Use ◽  
Specially Protected Natural Territories

The influence of recreation being a set of measures to restore health and recreation, on the main components of forest phytocenoses in specially protected natural territories of the Tatishchevsky district of the Saratov region has been studied for the first time. These phytocenoses have been intensively used for tourism for a long time. The intensity and visits activity of protected areas has been determined; the recreational capacity of territorial objects has been studied. The degree of forest landscapes has been revealed in specially protected natural territories. The findings allow predicting the future state of the natural resources of the Saratov region and can be taken into account when assessing their optimal use.

Rhythmic Prose in Imperial Greek Literature

2018 ◽  
Author(s):  
G. O. Hutchinson
Keyword(s):  
The Novel ◽  
Greek Literature ◽  
System A ◽  
First Time

The chapter looks at the division between poetry and prose in ancient and other literatures, and shows the importance of rhythmic patterning in ancient prose. The development of rhythmic prose in Greek and Latin is sketched, the system explained and illustrated (from Latin). It is firmly established, for the first time, which of the main Greek non-Christian authors 31 BC–AD 300 write rhythmically. The method takes a substantial sample of random sentence-endings (usually 400) from each of a large number of Imperial authors; it compares that sample with one sample of the same size (400) drawn randomly from a range of authors earlier than the invention of this rhythmic system. A particular sort of X2-test is applied. Many Imperial authors, it emerges, write rhythmically; many do not. The genres most likely to offer rhythmic writing are, unexpectedly, narrative: historiography and the novel.

scholarly journals Waterborne Polyurea Coatings Filled with Sulfonated Graphene Improved Anti-Corrosion Performance

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 251
Author(s):  
Jijia Zhang ◽  
Jihu Wang ◽  
Shaoguo Wen ◽  
Siwei Li ◽  
Yabo Chen ◽  
...  
Keyword(s):  
Composite Coating ◽  
Water Resistance ◽  
Electrochemical Impedance ◽  
Water Immersion ◽  
Doping Content ◽  
Corrosion Performance ◽  
Water Contact ◽  
Sulfonated Graphene ◽  
Long Time ◽  
Scanning Electron

In this paper, an environmentally friendly waterborne polyurea (WPUA) emulsion and its corresponding coating were prepared, which was characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM). To improve the performance of the coating, we doped sulfonated graphene (SG) into WPUA to prepare composite coating (SG/WPUA). SG can be uniformly dispersed in WPUA emulsion and is stable for a long time (28 days) without delamination. The water resistance of the composite coating with 0.3 wt.% SG nanofiller was improved; the water contact angle (WCA) result was SG/WPUA (89°) > WPUA (48.5°), and water absorption result was SG/WPUA (2.90%) < WPUA (9.98%). After water immersion treatment, SEM observation revealed that the SG/WPUA film only generated enlarged microcracks (100 nm) instead of holes (150–400 nm, WPUA film). Polarization curves and electrochemical impedance spectroscopy (EIS) tests show that SG nanosheets with low doping content (0.3 wt.%) are more conducive to the corrosion resistance of WPUA coatings, and the model was established to explain the mechanism.

scholarly journals Electromagnetic power of lightning superbolts from Earth to space

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J.-F. Ripoll ◽  
T. Farges ◽  
D. M. Malaspina ◽  
G. S. Cunningham ◽  
E. H. Lay ◽  
...  
Keyword(s):  
Low Frequency ◽  
Optical Emission ◽  
High Energy ◽  
Very Low Frequency ◽  
Electromagnetic Power ◽  
Power Spectral ◽  
High Energy Tail ◽  
Van Allen Probes ◽  
Long Time ◽  
Low Frequency Waves

AbstractLightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

scholarly journals Clinical significance of late diastolic tissue doppler parameters after onset of STEMI: from the view point of the timing of the echocardipography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
N Iwahashi ◽  
J Kirigaya ◽  
M Horii ◽  
T Abe ◽  
E Akiyama ◽  
...  
Keyword(s):  
Tissue Doppler ◽  
Atrial Function ◽  
Diastolic Velocity ◽  
Long Time ◽  
Group A ◽  
St Elevation ◽  
Group B ◽  
First Time

Abstract Background The early transmitral flow velocity (E) divided by the early diastolic velocity of the mitral valve annulus (e') is referred to as the “E/e' ratio,” is useful even for ST elevation acute myocardial infarction (STEMI). However, the role of late diastolic velocity (a') which reveals the atrial function for STEMI is still unclear. Objectives We evaluated the clinical usefulness of tissue Doppler including atrial function for a first-time STEMI by long time follow up. Furthermore, we evaluated the meaning of each parameters by performing immediately after PCI or 2 weeks later. Methods We treated consecutive 571 first-time STEMI patients by immediate PCI within 12 hours after onset, and we examined 270 patients at immediately after PCI (GroupA, 65 years, 250 male) and 301 patients at 2 weeks after onset (GroupB, 64 years, 243 male). We examined trans mitral flow and TDI, then defined E/e' as LV filling pressure and A/a' as left atrial function. We followed them for a long time (&gt;5 years). The primary end point (PE) was cardiac death or re-admission for heart failure (HF). Results We followed the patients in Group A for 10 years, Group B for 5 years. PE occurred in 64 patients in GroupA during 10 years, and 45 patients in GroupB during 5 years. We analyzed the univariate and multivariate Cox hazard analyses and we compared e' and a', E/e' and A/a' (Table). In GroupA, a' and A/a' were the independent predictors, on the other hand neither a' nor A/a' were the predictors in GroupB. E/e' was an independent predictor both in GroupA and B. Conclusion TDI parameters have different meanings by the timing of echocardiography after onset of a first-time STEMI. These results demonstrated that atrial dysfunction immediately after onset of STEMI suggests the poor prognosis after STEMI. Cox Hazard Proportional Analysis Funding Acknowledgement Type of funding source: None

scholarly journals Determination of the Distribution of Relaxation Times by Means of Pulse Evaluation for Offline and Online Diagnosis of Lithium-Ion Batteries

Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 36
Author(s):  
Erik Goldammer ◽  
Julia Kowal
Keyword(s):  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Sampling Rate ◽  
Relaxation Times ◽  
Low Frequency ◽  
Lithium Ion ◽  
Battery Management ◽  
Time Constants ◽  
Time Domain Data ◽  
Aging Study

The distribution of relaxation times (DRT) analysis of impedance spectra is a proven method to determine the number of occurring polarization processes in lithium-ion batteries (LIBs), their polarization contributions and characteristic time constants. Direct measurement of a spectrum by means of electrochemical impedance spectroscopy (EIS), however, suffers from a high expenditure of time for low-frequency impedances and a lack of general availability in most online applications. In this study, a method is presented to derive the DRT by evaluating the relaxation voltage after a current pulse. The method was experimentally validated using both EIS and the proposed pulse evaluation to determine the DRT of automotive pouch-cells and an aging study was carried out. The DRT derived from time domain data provided improved resolution of processes with large time constants and therefore enabled changes in low-frequency impedance and the correlated degradation mechanisms to be identified. One of the polarization contributions identified could be determined as an indicator for the potential risk of plating. The novel, general approach for batteries was tested with a sampling rate of 10 Hz and only requires relaxation periods. Therefore, the method is applicable in battery management systems and contributes to improving the reliability and safety of LIBs.

The electrocatalytic response of metallophthalocyanines when clicked to electrodes and to nanomaterials

2021 ◽  
Author(s):  
◽  
Lekhetho Simon Mpeta
Keyword(s):  
Hydrogen Peroxide ◽  
Silver Nanoparticles ◽  
Zinc Oxide ◽  
Photoelectron Spectroscopy ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Modified Electrodes ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Electrochemical Microscopy

Conjugates of nanomaterials and metallophthalocyanines (MPcs) have been prepared and their electrocatalytic activity studied. The prepared nanomaterials are zinc oxide and silver nanoparticles, reduced graphene oxide nanosheets and semiconductor quantum dots. The MPcs used in this work are cobalt (II) (1a), manganese(III) (1b) and iron (II) (1c) 2,9(10),16(17),23(24)- tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyaninato, 2,9(10),16(17),23(24)- tetrakis(5-pentyn-oxy) cobalt (II) phthalocyaninato (2), 9(10),16(17),23(24)- tris-[4-tert-butylphenoxy)-2- (4-ethylbezyl-oxy) cobalt (II) phthalocyaninato (3), 9(10),16(17),23(24)- tris-[4-tertbutylphenoxy)-2-(pent-4yn-yloxy)] cobalt (II) phthalocyaninato (4), cobalt (II) (5a) and manganese (III) (5b) 2,9(10),16(17),23(24)- tetrakis [4-(4-(5-chloro-1H-benzo [d]imidazol-2-yl)phenoxy] phthalocyaninato and 9(10),16(17),23(24)- tris tert butyl phenoxy- 2- [4-(4-(5-chloro-1H-benzo[d]imidazole-2-yl)phenoxy] cobalt (II) phthalocyaninato (6). Some of these MPcs (1a, 3 and 4) were directly clicked on azide grafted electrode, while some (1b, 1c, 2, 5a and 5b) were clicked to azide functionalised nanomaterials and then drop-dried on the electrodes. One phthalocyanine (5b) was drop-dried on the electrode then silver nanoparticles were electrodeposited on it taking advantage of metal-N bond. Scanning electrochemical microscopy, voltammetry, chronoamperometry, electrochemical impedance spectroscopy are among electrochemical methods used to characterise modified electrodes. Transmission electron microscopy, X-ray photoelectron spectroscopy, Xray diffractometry, Raman spectroscopy and infrared spectroscopy were employed to study surface functionalities, morphology and topography of the nanomaterials and complexes. Electrocatalytic activity of the developed materials were studied towards oxidation of 2-mercaptoethanol, hydrazine and hydrogen peroxide while the reduction study was based on oxygen and hydrogen peroxide. In general, the conjugates displayed superior catalytic activity when compared to individual materials. Complex 2 alone and when conjugated to zinc oxide nanoparticles were studied for their nonlinear optical behaviour. And the same materials were explored for their hydrazine detection capability. The aim of this study was to develop sensitive, selective and affordable sensors for selected organic waste pollutants. Conjugates were found to achieve the aim of the study compared to when individual materials were employed.

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