scholarly journals Implementation of coulometric titration system at constant current for developing of certified materials as primary standards

2017 ◽  
Vol 786 ◽  
pp. 012041
Author(s):  
H Suarez ◽  
R Cristancho ◽  
F Peralta ◽  
H Torres
Keyword(s):  
Coulometric Titration ◽  
Constant Current ◽  
Primary Standards ◽  
Titration System

Elektrochemische Untersuchung der chemischen Diffusion in Wüstit mit Hilfe eines oxidischen Festelektrolyten/ Electrochemical Investigation of Chemical Diffusion in Wüstite Using a Solid Oxide Electrolyte

1974 ◽  
Vol 29 (12) ◽  
pp. 1849-1859 ◽  
Author(s):  
H. Rickert ◽  
W. Weppner
Keyword(s):  
Diffusion Coefficient ◽  
Chemical Potential ◽  
Coulometric Titration ◽  
Chemical Diffusion ◽  
Tracer Diffusion ◽  
Correlation Factor ◽  
Galvanic Cell ◽  
Constant Current ◽  
Chemical Diffusion Coefficient ◽  
Small Constant

Chemical diffusion measurements in wüstite were carried out with the help of the solid state galvanic cell pO₂, Ptl |ZrO2(+Y2O3)| Fe1 - δ(ϰ)O| Pt2, N2 with doped ZrO2 as a solid electrolyte which exhibits practically pure conduction for oxygen ions. Starting from an initial homogeneous stoichiometry as given by δ, the voltage E of the cell, i. e. the chemical potential of oxygen (or δ) in Fe1 - δO at the phase boundary with the electrolyte, was changed in small steps, corresponding to 3,5 - 15% of the whole stoichiometric range. The re-equilibration of the compound was observed by the current as a function of time. Alternatively, a small constant current was applied to the galvanic cell and the voltage between the wüstite and a reference electrode was measured. From the relaxation behaviour the chemical diffusion coefficient can be determined in several ways. The values are consistent with those calculated from tracer diffusion coefficients, the thermodynamic factor, which could be estimated from coulometric titration measurements, and a correlation factor of the order of 1. In contradiction to previous results with thermogravimetric methods the chemical diffusion coefficient increases with growing deviation from the ideal stoichiometry.

scholarly journals Determination of Trace Amounts of Hydrofluoric Acid in Non-Aqueous Solutions by the Coulometric Titration Method

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4439 ◽  
Author(s):  
Cairui Huang ◽  
Congcong Shen ◽  
Ling Jin ◽  
Hongwei Cai
Keyword(s):  
Aqueous Solutions ◽  
Hydrofluoric Acid ◽  
Coulometric Titration ◽  
Accurate Determination ◽  
Ethanol Solution ◽  
Constant Current ◽  
Electrode Pair ◽  
Working Electrode ◽  
Relative Standard

For monitoring of trace amounts of hydrofluoric acid in the organic fluorine chemical industry, a facile method for determination of the hydrofluoric acid in an ethanol solution of lithium chloride, by coulometric titration, was proposed. Relying on homemade acid–base coulometric autotitrator, the electrolyte was 0.50 mol·L−1 LiCl ethanol solution and the constant current intensity was 0.2–2 mA. As for the working electrode pair, a platinum plate was used as a working electrode, and a platinum wire was used as an auxiliary electrode. The indicating electrode was the pH composite glass electrode and the titration endpoint was pH 5.50. The results showed that the relative standard deviation was below 2.0%, as the content of the hydrofluoric acid was between 2 μg to 100 μg. The recovery rate was 99.0–102.0%. This proposed route has the advantages of simplicity, convenience, quickness, accuracy, and automation, which can be applied to the accurate determination of trace amounts of hydrofluoric acid, in non-aqueous solutions.

Constant-Current Coulometric Titration of Hydrochloric Acid

1996 ◽  
Vol 73 (7) ◽  
pp. 679 ◽  
Author(s):  
James Swim ◽  
Edward Earps ◽  
Laura M. Reed ◽  
David Paul
Keyword(s):  
Hydrochloric Acid ◽  
Coulometric Titration ◽  
Constant Current

Scanning tunneling microscopy of polymers: A status report

1989 ◽  
Vol 47 ◽  
pp. 330-331
Author(s):  
P.E. Russell ◽  
I.H. Musselman
Keyword(s):  
High Resolution ◽  
Scanning Tunneling Microscopy ◽  
Sample Surface ◽  
Atomic Scale ◽  
Constant Current ◽  
Scanning Tunneling ◽  
Status Report ◽  
Tunneling Microscopy ◽  
Research Issues ◽  
Wide Range

Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.

Cerebellopontine Angle Surgery Assisted by Continuous Mapping of the Facial Nerve Via the Ultrasonic Aspirator

2020 ◽  
Author(s):  
Marco Cenzato ◽  
Roberto Stefini ◽  
Francesco Zenga ◽  
Maurizio Piparo ◽  
Alberto Debernardi ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Facial Nerve ◽  
Cerebellopontine Angle ◽  
Continuous Mapping ◽  
Cost Effective ◽  
Current Intensity ◽  
Vestibular Schwannomas ◽  
Constant Current ◽  
Surgical Workflow ◽  
Ultrasonic Aspirator

Abstract Background Cerebellopontine angle (CPA) surgery carries the risk of lesioning the facial nerve. The goal of preserving the integrity of the facial nerve is usually pursued with intermittent electrical stimulation using a handheld probe that is alternated with the resection. We report our experience with continuous electrical stimulation delivered via the ultrasonic aspirator (UA) used for the resection of a series of vestibular schwannomas. Methods A total of 17 patients with vestibular schwannomas, operated on between 2010 and 2018, were included in this study. A constant-current stimulator was coupled to the UA used for the resection, delivering square-wave pulses throughout the resection. The muscle responses from upper and lower face muscles triggered by the electrical stimulation were displayed continuously on multichannel neurophysiologic equipment. The careful titration of the electrical stimulation delivered through the UA while tapering the current intensity with the progression of the resection was used as the main strategy. Results All operations were performed successfully, and facial nerve conduction was maintained in all patients except one, in whom a permanent lesion of the facial nerve followed a miscommunication to the neurosurgeon. Conclusion The coupling of the electrical stimulation to the UA provided the neurosurgeon with an efficient and cost-effective tool and allowed a safe resection. Positive responses were obtained from the facial muscles with low current intensity (lowest intensity: 0.1 mA). The availability of a resection tool paired with a stimulator allowed the surgeon to improve the surgical workflow because fewer interruptions were necessary to stimulate the facial nerve via a handheld probe.

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