1,721,201 research outputs found
Modeling and Characterization of Metal/SiC Interface for Power Device Application
Full text linkSilicon carbide is a wide band-gap semiconductor widely considered
to be an excellent material for the fabrication of power devices
able to operate in extreme environmental conditions. Its superior
properties such as wide energy bandgap, high hardness, chemical
inertness, high electrical field breakdown strength and high thermal
conductivity enable electronic devices, based on it, to operate at
high temperatures, high voltages and high frequencies and make it
an attractive semiconducting material for the power electronics industry.
Since 1999 a number of electronic devices based on silicon
carbide are commercially available such as Schottky barrier diodes
with voltage rating of 300 - 1700 V (as of 2011) which often show
non-ideal electrical behavior.
Non-ideal electrical behavior is manifested in the abnormal current-voltage characteristics and greater than unity ideality factors.
Various theories exist as to the origin of these non-idealities some attribute
them to different conduction mechanisms such as generation-recombination
and edge-related currents and others to the inhomogeneous
Schottky barrier. We have considered the approach,
taken by Tung, which can explain all the non-ideal behaviors with
thermionic emission theory alone by assuming the Schottky barrier
height to be inhomogeneous. Inhomogeneous Schottky barrier implies
spatially varying isolated low barrier height regions existing
alongside a homogeneous high Schottky barrier. These regions are
supposed to interact, in case of being situated together, resulting in
the region with low barrier height to be pinched-off. If the pinch-off
occurs the low barrier height region (or patch depending on the
shape) has a Schottky barrier height equal to the 'saddle point potential'
in front of that patch or low barrier region. Whole Schottky
barrier is assumed to be composed of numerous such low barrier
height patches. These patches are considered to be embedded into
the high background Schottky barrier and define the overall current
transport through the Schottky barrier diode. A similar model is
the parallel conduction model presented by D. Defives et al. which
instead of considering the Schottky barrier to be composed of various
small patches, divides the Schottky barrier into two major parts
each with different Schottky barrier height and both existing simultaneously
within one Schottky barrier diode. Though accurate to
some extent, this model considers the two Schottky barrier heights
to be electrically independent of each other; which is not true in all situations. After applying Tung's theoretical model it was possible
to extract nearly correct value of Richardson constant for the Schottky
diodes with titanium and molybdenum Schottky contacts on 4H
silicon carbide. It was also possible to fit the experimental data correctly
with Tung's theoretical model. Note: The diodes used in this
research work were fabricated during a research project involving
Vishay and Politecnico di Torino
sj-docx-1-pie-10.1177_09544089221148294 - Supplemental material for Exploration of the dynamics of non-Newtonian Casson fluid subject to viscous dissipation and Joule heating between parallel walls due to buoyancy forces and pressure
No full textSupplemental material, sj-docx-1-pie-10.1177_09544089221148294 for Exploration of the dynamics
of non-Newtonian Casson fluid subject to viscous dissipation and Joule heating between parallel walls due to buoyancy forces and pressure by Zaheer Abbas, Muhammad Yousuf Rafiq, Hina Asghar and Sabeeh Khaliq in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
Characterization of the carbonic anhydrase gene family and other key osmoregulatory genes in Australian freshwater crayfish (genus Cherax)
No full textCherax quadricarinatus (Redclaw), C. destructor (Yabby) and C. cainii (Marron) are a group of economically important freshwater crayfish and have been developed for aquaculture production in many countries. As crayfish are farmed in a wide range of culture conditions, optimisation of water quality parameters, are crucial for their maximum growth performance. Previous reports have shown that fluctuations in water quality can negatively impact on growth of crayfish. Therefore, this project aims to identify and characterize the major genes that enable freshwater crayfish to persist in different water chemistries and evaluate their patterns of expression under different water parameters. Overall, this project found a number of candidate genes in all three species and determined that water chemistry had a strong influence on the expression of candidate genes. This information is important in the optimization of water quality parameters in freshwater crayfish aquaculture production
Fabrication of Ni/Ti/Al Schottky contact to n-type 4H-SiC under various annealing conditions
Full text linkForward I-V characteristics of a silicon carbide Schottky diode, with triple layer metallization Ni/Ti/Al as Schottky contact, are presented. Effects of different annealing conditions on the Schottky barrier height and ideality factor are discussed. The diodes were annealed in inert Ar atmosphere for 30 minutes at temperatures ranging from 600 °C to 800 °C. The ideality factors of the four diodes, chosen out of 20 diodes, range from 1.02 to 1.13 and the Schottky barrier heights range from 1.47 eV to 3.17 e
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Analysis, characterisation and expression of gill-expressed carbonic anhydrase genes in the freshwater crayfish Cherax quadricarinatus
No full textChanges in water quality parameters such as pH and salinity can have a significant effect on productivity of aquaculture species. Similarly, relative osmotic pressure influences various physiological processes and regulates expression of a number of osmoregulatory genes. Among those, carbonic anhydrase (CA) plays a key role in systemic acid–base balance and ion regulation. Redclaw crayfish (Cherax quadricarinatus) are unique in their ability to thrive in environments with naturally varied pH levels, suggesting unique adaptation to pH stress. To date, however, no studies have focused on identification and characterisation of CA or other osmoregulatory genes in C. quadricarinatus. Here, we analysed the redclaw gill transcriptome and characterized CA genes along with a number of other key osmoregulatory genes that were identified in the transcriptome. We also examined patterns of gene expression of these CA genes when exposed to three pH treatments.\ud
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In total, 72,382,710 paired end Illumina reads were assembled into 36,128 contigs with an average length of 800 bp. Approximately 37% of contigs received significant BLAST hits and 22% were assigned gene ontology terms. Three full length CA isoforms; cytoplasmic CA (ChqCAc), glycosyl-phosphatidylinositol-linked CA (ChqCAg), and β-CA (ChqCA-beta) as well as two partial CA gene sequences were identified. Both partial CA genes showed high similarity to ChqCAg and appeared to be duplicated from the ChqCAg. Full length coding sequences of Na+/K+-ATPase, V-type H+-ATPase, sarcoplasmic Ca+-ATPase, arginine kinase, calreticulin and Cl− channel protein 2 were also identified. Only the ChqCAc gene showed significant differences in expression across the three pH treatments.\ud
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These data provide valuable information on the gill expressed CA genes and their expression patterns in freshwater crayfish. Overall our data suggest an important role for the ChqCAc gene in response to changes in pH and in systemic acid–base balance in freshwater crayfish
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