scholarly journals Dissolution and Reprecipitation of Sulfur on Carbon Surface

2021 ◽  
Author(s):  
Jingdong Liu ◽  
Yuanhui Zheng
Keyword(s):  
Redox Process ◽  
Disproportionation Reaction ◽  
Carbon Surface ◽  
Main Process ◽  
Discharge Process ◽  
Impedance Spectra ◽  
Discharge Curve ◽  
Before And After ◽  
Solid Film ◽  
Coulomb Efficiency

Abstract Further understanding of the redox process of lithium polysulfides (PSs) on carbon surface is helpful to design Li/S batteries with better performance. “Shuttle mechanism” can explain the low coulomb efficiency and self-discharge of a Li/S battery, but it cannot explain the fact that battery performance is closely affected by electrolyte volume and sulfur load. This paper aims to reveal main redox process of PSs on surface of carbon by examining cathodic behavior with different electrolyte volume and sulfur load. SEM photos and Impedance Spectra of cathode before and after 1st discharge were compared, it was found that the discharge process is the continuous dissolution of sulfur composited with carbon into the electrolyte to form PSs, at the same time, PSs re-precipitates sulfur on the surface of cathode through disproportionation reaction to form a solid film. CV curves showed that the solid film passivates electrode, and the electrode is activated only when potential sweeps negatively and Li2S is generated. When lean electrolyte is used, there is fluctuation in CV curves, which proves that the dissolution-reprecipitation of sulfur is the main process of cathode. The discharge-charge curves of cathodes with different sulfur load were compared, it was found that there is wavy fluctuation in the discharge curve with high sulfur load, which proves again that the sulfur reaction dominates the electrode process.

Study on Thermal Regeneration for Caffeine-Saturated Activated Carbon

2013 ◽  
Vol 781-784 ◽  
pp. 1941-1944 ◽  
Author(s):  
Zhao You Zhu ◽  
Li Li Wang ◽  
Wan Ling Wang ◽  
Ying Long Wang
Keyword(s):  
Activated Carbon ◽  
Carbon Layer ◽  
Carbon Surface ◽  
Optimum Conditions ◽  
Gas Velocity ◽  
Thermal Regeneration ◽  
Regeneration Time ◽  
Before And After ◽  
Carbon Regeneration ◽  
Carrier Gas Velocity

Waste activated carbon (AC) containing caffeine was produced during the process of the production for caffeine. The process of treatment caffeine-saturated AC using thermal regeneration was explored and factors on the regeneration of activated carbon were investigated. The optimum conditions obtained were: temperature is 650 °C, the regeneration time is 180 min, the carrier gas velocity is 0.002 m/s, carbon layer thickness is 0.1 m. Under these conditions, activated carbon regeneration efficiency reached 90.3%. In addition, the pore structure of activated carbon before and after regeneration was characterized and the activated carbon surface area and pore size distribution under optimum conditions were determined by the adsorption isotherms.

scholarly journals Psychiatric admission for homeless people: the impact of a specialist community mental health team

1997 ◽  
Vol 21 (5) ◽  
pp. 260-263 ◽  
Author(s):  
Martin Commander ◽  
Sue Odell ◽  
Sashi Sashidharan
Keyword(s):  
Mental Health ◽  
Community Mental Health ◽  
Homeless People ◽  
Discharge Process ◽  
Community Mental Health Team ◽  
Psychiatric Admission ◽  
Mental Health Team ◽  
Health Team ◽  
Before And After ◽  
The Impact

The difficulty in achieving good quality community mental health care for homeless people has received increasing attention during the last few years. Less consideration has been given to the provision of inpatient care. By comparing data collected before and after its inception, we examined the impact of a specialist community mental health team for homeless people on ‘no fixed abode’ admissions in Birmingham. Although the team was successfully involved in the admission and discharge process in a substantial proportion of cases, many admissions still took place out of hours and involved the police, while discharge was often against medical advice and occurred without follow-up. These findings and their implications for the provision of homeless services are discussed.

scholarly journals Turbulent Flow Measurements near the Discharge Port of a Screw Compressor

2019 ◽  
Vol 104 (4) ◽  
pp. 927-946
Author(s):  
J. M. Nouri ◽  
D. Guerrato ◽  
N. Stosic
Keyword(s):  
Time Window ◽  
Rapid Change ◽  
Jet Flows ◽  
Screw Compressor ◽  
Discharge Process ◽  
Sudden Increase ◽  
Mean Flow ◽  
Flow Measurements ◽  
Male And Female ◽  
Before And After

Abstract Mean flow and turbulence characteristics have been measured within the male and female rotors close to the discharge port of a double screw compressor at different radial positions, two axial positions from the exit port, Hp, and two radial planes, αp. Cycle-resolved axial and tangential mean flow measurements and their corresponding turbulent velocity fluctuations were made over a time window of 1° using a laser Doppler velocimetry, LDV, system. Measurements were performed through two transparent windows near the inlet of the discharge port inside the male and female working chambers. The results revealed a highly complex 3-D flow within the male and female working chambers, in particular, near the discharge port with two distinct flow zones 1 and 2 before and after the opening of the port, respectively. The flow in zone 1 was controlled by the rotor motion while in zone 2 was greatly influenced by the discharge process. In zone 2, both components of mean velocities were subjected to a sudden increase in velocity forming strong axial and tangential jet flows due to rapid change in pressure across the port as the flow is exposed into the discharge port. It was found that the flow structures have been affected considerably by the position of the discharge port, radial planes and radial positions. Axial and tangential RMS velocity distributions within both rotors were found to be relatively high and less affected by the flow changes of zones 1 and 2 with almost uniform distribution. The measured magnitudes of axial and tangential RMS velocities suggest it would be reasonable to assume the local turbulence to be isotropic for the modelling purposes. To authors’ knowledge, the results are unique, original and in great details not only to describe the flow structure, but also, they can be used in CFD codes to establish a reliable model of the flow and pressure distribution within twin screw machines.

Improved Supervision and Safety of Discharges Through Formal Discharge Education

2018 ◽  
Vol 34 (3) ◽  
pp. 226-233
Author(s):  
Lily L. Ackermann ◽  
Emily A. Stewart ◽  
Jeffrey M. Riggio
Keyword(s):  
High Risk ◽  
Current Model ◽  
Discharge Process ◽  
Discharge Instructions ◽  
Post Intervention ◽  
Internal Medicine Residents ◽  
Before And After ◽  
Attending Physicians ◽  
Discharge Education

The goal of this study is to evaluate change in residents’ assessment of supervision and safety of the discharge process after formal discharge instruction education. An educational lecture and workshop addressing high-risk medications, medication reconciliation, follow-up, and handoffs were provided to internal medicine residents. Residents were given a longitudinal survey before and after the discharge education session. Significant improvement in perception was demonstrated in review of discharge instructions ( P < .001), review of new medications/side effects with patients ( P < .001), and review of discharge instructions with and receiving feedback from attending physicians ( P < .001). On review of 40 discharge instructions pre and post intervention, there was an improvement in completion of instructions for high-risk medications ( P < .05 [14 insulin, 26 anticoagulation]). This intervention was viewed positively by residents; more than two thirds of all residents favored a process of formal training over the current model of “training by doing.”

INCREASE OF EFFICIENCY OF Li+-INTERCALATED CURRENT GENERATION IN SUPRAMOLECULAR ENSEMBLES WITH HIERARCHICAL ARCHITECTURE MCM-41〈HYDROQUINONE〉

2013 ◽  
Vol 12 (05) ◽  
pp. 1350037
Author(s):  
D. V. MATULKA ◽  
I. I. GRYGORCHAK ◽  
B. A. LUKIYANETS
Keyword(s):  
Diffusion Coefficient ◽  
Theoretical Model ◽  
Hierarchical Structure ◽  
Hierarchical Architecture ◽  
Discharge Process ◽  
Current Generation ◽  
Cathode Process ◽  
Discharge Curve ◽  
Supramolecular Ensembles ◽  
Mcm 41

Double-matrix hierarchical structure of the 〈molecular-lattice matrix MCM-41〈hydroquinone〉〉 is synthesized. Its use in the cathode process in the Li +-intercalation current generation showed a significant improvement in the structure of the discharge curve and the practical constancy of diffusion coefficient throughout the discharge process. Theoretical model describing the peculiarities of observed characteristics in the structure is presented.

Thermal and Thermo-Oxidative Degradation of PBO: Determination of Kinetics and Reaction Products

1993 ◽  
Vol 11 (2) ◽  
pp. 156-171 ◽  
Author(s):  
Charles A. Nielsen ◽  
Peter Pierini ◽  
Steve Fuh
Keyword(s):  
Oxidative Degradation ◽  
Weight Percent ◽  
Decomposition Reaction ◽  
Polyimide Film ◽  
Reaction Products ◽  
Limiting Oxygen Index ◽  
Excellent Thermal Stability ◽  
Degradation Rates ◽  
Before And After ◽  
Solid Film

Poly(para-phenylene- cis-benzobisoxazole), PBO, is a promising thermal and fire resistant material because of its excellent thermal stability, virtual nonflammability (limiting oxygen index = 56), high char yield, and negligible smoke generation [1]. Decomposition reaction products and kinetics were studied to further characterize this material. Chemical changes in the solid film were studied by FTIR (Fourier transform infrared spectroscopy) before and after isothermal heating in vacuum. Decom position was detected at 600°C while little, if any, was observed at 500°C. In other studies using a constant heating rate, released volatiles were identified by FTIR and an electrochemical selective ion probe. Degradation rates in nitrogen (thermal) and air (thermo-oxidative) were de termined by isothermal thermogravimetric analysis (ITGA). Activation ener gies for the thermal and thermo-oxidative degradations were calculated. These results are compared to other thermally resistant polymers. For example, the PBO film decomposition rate is over one hundred times slower than a high- temperature-resistant polyimide (Kapton® H film) in nitrogen, and about two times slower than the polyimide film in air. These findings suggest possible lower rates of combustion, especially in situations where the polymer is decom posed in a locally oxygen starved environment. Finally, an empirical model for the thermo-oxidation of PBO was obtained from the TGA data. Reliable predictions of weight percent remaining are made as a function of time and temperature.

The Effect of Electrochemical Modification of the Glass Carbon Surface in Conditions of Chemisorption of Fluorine-Containing Nanogroups on its Electrophysical Properties

MRS Advances ◽  
2017 ◽  
Vol 2 (54) ◽  
pp. 3335-3339
Author(s):  
Yulia M. Stryuchkova ◽  
Sergey M. Karabanov ◽  
Dmitriy V. Suvorov ◽  
Evgeniy V. Slivkin ◽  
Gennadiy P. Gololobov ◽  
...  
Keyword(s):  
Scanning Probe Microscopy ◽  
Tunneling Current ◽  
Atomic Scale ◽  
Carbon Surface ◽  
Electrophysical Properties ◽  
Electrode Processes ◽  
Electrochemical Modification ◽  
Before And After ◽  
Glass Carbon ◽  
Donor Acceptor

ABSTRACTThe electrophysical (donor-acceptor) properties of the of glass carbon (GC) surface before and after its electrochemical modification in conditions of chemisorption of fluorine-containing nanogroups were studied using the methods of scanning probe microscopy. The values of the coefficients characterizing local (for atomic-scale) electrophysical properties of the surface are calculated on the basis of obtained local spectral dependences of the tunneling current on the tunnelling voltage. Fluorination of the GC surface resulted in change of the ratio of its donor-acceptor atomic characteristics, acceleration of electrode processes, and increase of the overall tunneling activity of local places.

Two Surface Treatment Processes and Their Influence on Magnesium Electrochemical Activity

2008 ◽  
Vol 373-374 ◽  
pp. 513-516
Author(s):  
Jun Quan Liu ◽  
Run Feng Zhao ◽  
Neng B. Li
Keyword(s):  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Electrochemical Impedance ◽  
Impedance Measurement ◽  
Discharge Process ◽  
Discharge Performance ◽  
Current Step ◽  
Substrate Metal ◽  
Treatment Processes ◽  
Before And After

Two different surface treatments were adopted to form the film layers whose equivalent circuits were simulated by electrochemical impedance measurement. Discharge performance of each treated surface was studied by the electrochemical, potential step and current step in sodium chloride solution. The microstructures of treated and blank magnesium were observed by scanning electron microscopy (SEM) before and after discharge. According to the SEM observation, the discharge process of the sample treated by the nickel electroless plating had been deduced. For the electroless magnesium alloy, the experiments have proved that not only does the activity appear in the range of coating thickness, but the activity continues in the substrate metal under coating.

scholarly journals Impedance spectroscopy characterization of an interdigital structure for continuous particle measurements in wood-driven heating systems

2015 ◽  
Vol 4 (1) ◽  
pp. 37-44 ◽  
Author(s):  
A. Weiss ◽  
M. Bauer ◽  
S. Eichenauer ◽  
E. A. Stadlbauer ◽  
C.-D. Kohl
Keyword(s):  
Impedance Spectra ◽  
Thermal Regeneration ◽  
Heating Systems ◽  
Particle Measurements ◽  
Before And After ◽  
Signal Evaluation ◽  
Online Measurements ◽  
Exhaust Stream ◽  
And Control

Abstract. In the course of the climate change and increased focus on CO2-neutral energy sources, the use of wood-driven small heating systems (SHS) becomes more important. But, their contribution to air pollution, especially particulate matter, is about as high as the emissions from car engines. The specific formation of harmful substances in wood fires and possible countermeasures by continuously operating sensor and control systems are covered. Impedance spectra of interdigital electrode (IDE) structures are taken before and after mounting in wood-driven SHS to get information about the particles in the exhaust stream. It appears that the capacitive parts of the impedance spectra at a fixed frequency are appropriate for a fast signal evaluation. The good correlation with established offline measuring methods is discussed and the capability of thermal regeneration is demonstrated. The offline measurements of this work shall give the experimental basis for the development of online measurements in order to control the particle emissions of wood-driven SHS.

Influence of Ethanol as a Carburizing Agent on Carbon Surface Concentration and Microstructure of DIN 17NiCrMo7 Steel Gears

2015 ◽  
Author(s):  
Rogério Catalão ◽  
Omar Khayyam Ribas ◽  
José Rubens G. Carneiro ◽  
Érico Freitas ◽  
Larissa Vilela Costa ◽  
...  
Keyword(s):  
Shot Peening ◽  
Surface Concentration ◽  
Carbon Surface ◽  
Quantitative Chemical Analysis ◽  
X Ray Diffraction ◽  
Austenite Grain Size ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
The Impact

In the present work, the addition of ethanol to endothermic gas during the carburizing process of DIN 17NiCrMo7 steel gears was investigated with the objective of determining the impact on carbon surface concentration and microstructure. The materials were carburized at 870°C and 930°C, oil quenched, tempered and subsequently shot peened. Carburizing was carried out in a continuous industrial furnace for a total of 280 min. After quenching and tempering, the in-depth carbon concentrations were determined through quantitative chemical analysis and the resulting profiles were modeled in order to obtain carbon diffusivity constants. The amount of retained austenite and austenite grain size, determined by X-ray diffraction and optical microscopy, were found to increase with carburizing temperature. Residual stress profiles were also determined by X-ray diffraction before and after the shot-peening process. The microstructure of the specimens was further investigated by transmission electron microscopy, which revealed the presence of BCC martensite before and after shot-peening. The enrichment of the endothermic gas carrier with ethanol could be shown to be a viable option, allowing for surface concentrations of up to 0.8%C.

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