scholarly journals Preparation of clean MgO surface by oxygen plasma: Comparison with standard substrate cleaning procedures

2020 ◽  
Vol 38 (6) ◽  
pp. 062201
Author(s):  
Jacqueline Geler-Kremer ◽  
Agham B. Posadas ◽  
Alexander A. Demkov
Keyword(s):  
Oxygen Plasma ◽  
Cleaning Procedures ◽  
Mgo Surface ◽  
Substrate Cleaning

Etching of Polymers by Oxygen Plasma

1968 ◽  
Vol 26 ◽  
pp. 408-409
Author(s):  
Virgil Peck ◽  
W. L. Carter
Keyword(s):  
Molecular Weight ◽  
Oxygen Plasma ◽  
Flow Time ◽  
Microscopical Study ◽  
Surface Layers ◽  
Organic Vapors ◽  
Sample Position ◽  
Accuracy Of Measurement ◽  
Bulk Polymers ◽  
Electron Microscopical

Any electron microscopical study of the morphology of bulk polymers has throughout the years been hampered by the lack of any real ability to produce meaningful surface variations for replication. True etching of polymers should show crystalline and amorphous regions in some form of relief. The use of solvents, acids, organic vapors, and inert ion bombardment to etch samples has proved to be useful only in limited applications. Certainly many interpretations of these results are subject to question.The recent use of a radiofrequency (R. F.) plasma of oxygen to degrade and remove organic material with only minor heating has opened a new possibility for etching polymers. However, rigid control of oxygen flow, time, current, and sample position are necessary in order to obtain reproducible results. The action is confined to surface layers; the molecular weight of the polymer residue after heavy etching is the same as the molecular weight of the polymer before attack, within the accuracy of measurement.

INITIAL STEP OF SPECIALIZED CORPORA BUILDING: CLEANING PROCEDURES

2020 ◽  
Author(s):  
Vera Yakubson ◽  
Victor Zakharov
Keyword(s):  
Text Processing ◽  
Research Question ◽  
Initial Step ◽  
Main Research ◽  
Academic Texts ◽  
Linguistic Annotation ◽  
Significant Difference ◽  
Cleaning Procedures ◽  
Unique Source ◽  
Future Work

This paper deals with the specialized corpora building, specifically academic language corpus in the biotechnology field. Being a part of larger research devoted to creation and usage of specialized parallel corpus, this piece aims to analyze the initial step of corpus building. Our main research question was what procedures we need to implement to the texts before using them to develop the corpus. Analysis of previous research showed the significant quantity of papers devoted to corpora creation, including academic specialized corpora. Different sides of the process were analyzed in these researches, including the types of texts used, the principles of crawling, the recommended length of texts etc. As to the text processing for the needs of corpora creation, only the linguistic annotation issues were examined earlier. At the same time, the preliminary cleaning of texts before their usage in corpora may have significant influence on the corpus quality and its utility for the linguistic research. In this paper, we considered three small corpora derived from the same set of academic texts in the biotechnology field: “raw” corpus without any preliminary cleaning and two corpora with different level of cleaning. Using different Sketch Engine tools, we analyzed these corpora from the position of their future users, predominantly as sources for academic wordlists and specialized multi-word units. The conducted research showed very little difference between two cleaned corpora, meaning that only basic cleaning procedures such as removal of reference lists are can be useful in corpora design. At the same time, we found a significant difference between raw and cleaned corpora and argue that this difference can affect the quality of wordlists and multi-word terms extraction, therefore these cleaning procedures are meaningful. The main limitation of the study is that all texts were taken from the unique source, so the conclusions could be affected by this specific journal’s peculiarities. Therefore, the future work should be the verification of results on different text collections

Activation of EL-4 T-cells by irradiation with atmospheric oxygen plasma

2020 ◽  
Vol 59 (SJ) ◽  
pp. SJJF03
Author(s):  
Sitti Subaedah ◽  
Haruka Uematsu ◽  
Nobuya Hayashi
Keyword(s):  
T Cells ◽  
Oxygen Plasma ◽  
Atmospheric Oxygen

Diagnostics of hydrogen-oxygen plasma jet for application in gas thermal spraying

2020 ◽  
Vol 2020 (11) ◽  
pp. 41-45
Author(s):  
Yu.S. Popil ◽  
◽  
V.M. Korzh ◽  
V.Ya. Chernyak ◽  
Ye.A. Zakharov ◽  
...  
Keyword(s):  
Oxygen Plasma ◽  
Thermal Spraying ◽  
Plasma Jet

High Breakdown Voltage GaN HEMT Device Fabricated on Self-Standing GaN Substrate

2013 ◽  
Vol 347-350 ◽  
pp. 1535-1539
Author(s):  
Jian Jun Zhou ◽  
Liang Li ◽  
Hai Yan Lu ◽  
Ceng Kong ◽  
Yue Chan Kong ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Breakdown Voltage ◽  
Oxygen Plasma ◽  
Cutoff Frequency ◽  
Chemical Vapor ◽  
Current Gain ◽  
Organic Chemical ◽  
Oxygen Plasma Treatment ◽  
Gan Hemt ◽  
High Breakdown Voltage

In this letter, a high breakdown voltage GaN HEMT device fabricated on semi-insulating self-standing GaN substrate is presented. High quality AlGaN/GaN epilayer was grown on self-standing GaN substrate by metal organic chemical vapor deposition. A 0.8μm gate length GaN HEMT device was fabricated with oxygen plasma treatment. By using oxygen plasma treatment, gate forward working voltage is increased, and a breakdown voltage of more than 170V is demonstrated. The measured maximum drain current of the device is larger than 700 mA/mm at 4V gate bias voltage. The maximum transconductance of the device is 162 mS/mm. In addition, high frequency performance of the GaN HEMT device is also obtained. The current gain cutoff frequency and power gain cutoff frequency are 19.7 GHz and 32.8 GHz, respectively. A high fT-LG product of 15.76 GHzμm indicating that homoepitaxy technology is helpful to improve the frequency performance of the device.

Chemical functionalization of carbon/polymer bipolar plate materials via oxygen plasma activation and subsequent silanization

2014 ◽  
Vol 240 ◽  
pp. 255-260 ◽  
Author(s):  
Martin Schade ◽  
Steffen Franzka ◽  
Anja Schröter ◽  
Franco Cappuccio ◽  
Martyna Gajda ◽  
...  
Keyword(s):  
Oxygen Plasma ◽  
Bipolar Plate ◽  
Chemical Functionalization ◽  
Plasma Activation

scholarly journals On the Effectiveness of Oxygen Plasma and Alkali Surface Treatments to Modify the Properties of Polylactic Acid Scaffolds

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1643
Author(s):  
Ricardo Donate ◽  
María Elena Alemán-Domínguez ◽  
Mario Monzón
Keyword(s):  
Surface Properties ◽  
Enzymatic Degradation ◽  
Oxygen Plasma ◽  
Physicochemical Characterization ◽  
Surface Treatments ◽  
Carboxyl Groups ◽  
Scanning Calorimetry ◽  
Water Contact ◽  
Angle Measurements ◽  
3D Printed

Surface modification of 3D-printed PLA structures is a major issue in terms of increasing the biofunctionality and expanding the tissue engineering applications of these parts. In this paper, different exposure times were used for low-pressure oxygen plasma applied to PLA 3D-printed scaffolds. Alkali surface treatments were also evaluated, aiming to compare the modifications introduced on the surface properties by each strategy. Surface-treated samples were characterized through the quantification of carboxyl groups, energy-dispersive X-ray spectroscopy, water contact angle measurements, and differential scanning calorimetry analysis. The change in the surface properties was studied over a two-week period. In addition, an enzymatic degradation analysis was carried out to evaluate the effect of the surface treatments on the degradation profile of the 3D structures. The physicochemical characterization results suggest different mechanism pathways for each type of treatment. Alkali-treated scaffolds showed a higher concentration of carboxyl groups on their surface, which enhanced the enzymatic degradation rate, but were also proven to be more aggressive towards 3D-printed structures. In contrast, the application of the plasma treatments led to an increased hydrophilicity of the PLA surface without affecting the bulk properties. However, the changes on the properties were less steady over time.

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