bluuebunny/crossref_metadata_2025 huggingface dataset:
A molecular dynamics study concerning the effect of high-temperature and high-pressure on the structure and phase transition of Fe2O3 material
Authors: Trong Dung Nguyen , Long Van Cao , Dang Phu Nguyen , Ţălu Ştefan
Published: May 2022

This paper uses Molecular Dynamics (MD) method to study the influence of high temperature (T) and high pressure (P) on the structure and phase transition of Fe2O3 materials. The results show that, when increasing the temperature from T = 300 K to T = 7000 K, P = 0.0 GPa, the size (1) of the Fe2O3 materials increases, the energy (E) increases, the length link (r) decreased, the number of structural units FeO4, FeO5 increased, and FeO6 decreased. Similarly, as the pressure (P) is increased, from P = 0 GPa to P = 360 GPa at temperatures T, l decreases, E increases, r decreases, FeO4 decreases and disappears, FeO5 decreases, and FeO6 increases at high P with P ≥ 150 GPa, FeO5 disappeared at P ≥ 250 GPa and only FeO6 appeared at T = 2300, 7000 K. In addition, when increasing T, P, the bond angle of Fe–O–Fe, O–Fe–O decreases, E increases, r decreases, l increases when T increases and l decreases when P increases, leading to the number of structural units FeO4, FeO5 increasing and FeO6 decreasing when T increases and vice versa when P increases. In addition, the phase transition temperature (Tm), Tm = 2300 K was determined. All the obtained results will be the basis for future experimental studies of amorphous Fe2O3 materials.
Meshfree numerical integration for some challenging multi-term fractional order PDEs
Authors: Samad Abdul , Siddique Imran , Jarad Fahd
Published: May 2022

Fractional partial differential equations (PDEs) have key role in many physical, chemical, biological and economic problems. Different numerical techniques have been adopted to deal the multi-term FPDEs. In this article, the meshfree numerical scheme, Radial basis function (RBF) is discussed for some time-space fractional PDEs. The meshfree RBF method base on the Gaussian function and is used to test the numerical results of the time-space fractional PDE problems. Riesz fractional derivative and Grünwald-Letnikov fractional derivative techniques are used to deal the space fractional derivative terms while the time-fractional derivatives are iterated by Caputo derivative method. The accuracy of the suggested scheme is analyzed by using $ L_\infty $-norm. Stability and convergence analysis are also discussed.
POJEDINA OBILJEŽJA KVALITETE ŽIVOTA OSOBA S DUŠEVNIM SMETNJAMA – PERSPEKTIVA KORISNIKA USLUGE CASE MANAGEMENTA I OSOBA SMJEŠTENIH U DOM ZA ODRASLE
Authors: Mardešić Mia , Mužinić Marinić Lana
Published: May 2022

SOME ASPECTS OF QUALITY OF LIFE OF PEOPLE WITH MENTAL DISABILITIES – PERSPECTIVE OF CASE MANAGEMENT USERS AND PEOPLE IN MENTAL HEALTH FACILITIES ABSTRACT This paper presents two perspectives of people with mental disabilities on their perception of quality of life. Main aim of this paper was to develop a deeper knowledge about certain aspects of quality of life of people with mental health disabilities from the perspective of case management users and people in mental health facilities in the geographical area of Zagreb. Aspects of quality of life that we were interested in were: general health (physical and mental), social and environmental aspects (focusing on social transfers mostly). For this purpose, qualitative research approach was selected and data was collected through semi-structured interviews on the total sample of 8 users. Participants of this study were persons in direct contact with mental health facility »Dom za odrasle – Zagreb«. The mentioned mental health facility is providing case management program for their users, and therefore we had four participants from a case management group and four participants that were accommodated in the mental health facility. The results showed significant differences in social functioning, perception of mental health, as well as in environmental domain on behalf of case management users. Physical health is perceived better in mental health facilities. Key words: quality of life; people with mental disabilities; case management; metal health facilities; social work
ODNOS PREMA VLASTITOM STARENJU IZ PERSPEKTIVE ODRASLOG DOBA
Authors: Spasić Šnele Miljana , Anđelković Vesna
Published: May 2022

Although aging and old age are the subject of increasing research, the attitude towards one’s own aging seems to be insufficiently researched. This prompted us to examine whether the way we experience our own aging, as well as our attitudes towards older people, from adolescence and over a long period of adulthood, but also what is the role of gender and socioeconomic status (earnings and education). The survey was conducted in the Republic of Serbia and included 1,236 respondents (793 women and 443 men). A PORPOS3 battery was used, a purpose-built instrument with 343 questions, which also contains a short scale, Attitude towards one’s own aging with three dimensions: Concern about one’s own aging, Acceptance of aging and Attitude towards the elderly. The results shows that the respondents older than 61 years, in relation to the respondents from 31 to 40 years, but also that the respondents who earn up to 20,000.00 dinars, in relation to those who earn between 71,000.00 and 90,000.00 dinars, have a more negative attitude towards the elderly. In a sample of respondents between the ages of 41 and 50, a positive low-intensity correlation was obtained between concerns about one’s own aging and level of education.
Medical students’ self-directed learning skills during online learning amid the COVID-19 pandemic in a Korean medical school
Authors: Si Jihyun
Published: May 2022

Purpose: This study examined medical students’ self-directed learning skills in online learning contexts, and whether there were any differences among the student groups (from pre-medical program year 1 to medical program year 2) amid the coronavirus disease 2019 (COVID-19) pandemic. It also explored the components of self-directed learning skills influencing their perceived learnring performance and satisfaction in online learning contexts.Methods: This study used a cross-sectional survey design and convenience sampling. It was conducted in a Korean medical school, which delivered all courses online because of the COVID-19 pandemic. The self-directed learning skill survey, which included student satisfaction and perceived learning performance items, was disseminated over two weeks through email to the participants. The collected data were analyzed through descriptive statistics, analysis of variance, and multiple regressions.Results: The survey response rate was 70% (140/200). The overall mean of self-directed learning skills was 3.85. Students in medical year 2 showed the highest score (4.15), while students in medical year 1 showed the lowest score (3.69). The learning plan category score (3.74) was the lowest among the three categories. The pre-medical program year 1 students showed the lowest score in the perceived learning performance (3.16), and only the learning plan category impacted student satisfaction (t=2.605, p=0.041) and perceived learning performance (t=3.022, p=0.003).Conclusion: When designing online learning environments, it is imperative to provide features to help students set learning goals and search diverse online learning resources. In addition, it is an effective strategy to provide the students in medical program year 1 with self-directed learning skills training or support for successful online learning.
Joseph Benesch: A Forgotten Bohemian Violinist and an Imitator of Niccolò Paganini Within the Central European Violinistic Tradition
Authors: Zupančič Maruša
Published: May 2022

Joseph Benesch (1795–1873) was among the earliest violin virtuosos to become imitators of the famous Niccolò Paganini, whom he met in Trieste as early as 1824. He was active in Ljubljana for six years and later settled in Vienna, where he was a member of the Hofkapelle and orchestral director of the court theatre. He mainly wrote works for violin, which he performed as part of his personal repertoire
A Matrix-Based Guideline to Chemical Engineering Curricular Revision
Authors: Kamandhari Helen Hendaria , Lavandera Ponce Silvia , Rodríguez-Zúñiga Ursula Fabiola , Araujo Pantoja Patricia
Published: May 2022

The objective of the study is to describe our matrix-based guidelines in revising our competence-based curriculum. A curriculum restructure relies on pragmatic and iterative refinement of the situations integrating various stakeholders’ perspectives as well as field-based research by considering currently critical and emerging trends, such as the inclusion of the 21st century skills. The revision project took a 150-day duration and implemented the subsequent stages: 0). Build a common language 1). Identify aspects that are working well at the moment and those that may need revision in the current curriculum, 2). Align the performance indicators using the evaluation matrix, 3). Select types of learning activities that correlate with Bloom's taxonomy verbs, 4). Incorporate student learning autonomy into the curriculum. The matrix was used to facilitate equal, organized, and clearer distribution, thus, bringing the coherence of indicators for the 5-year progressive learning courses. The contribution of the study is to achieve comprehensive, systematic, and continuous improvement of the competence-based educational model for Latin American universities within engineering study programs.
Proposal of a Model for the Development of University Teacher Training Through Virtual Courses
Authors: Andrade-Arenas Laberiano , Llulluy Nuñez David , Vilchez Sandoval Jesús , Reyes Perez William , Gonzales Choquehuanca Elvis
Published: May 2022

In times of pandemic, the education sector, worldwide, was affected. To minimize the problem, they carried out strategies that allow the start of virtual classes optimally. Likewise, teachers had to be trained, to be at the forefront of the context. Training should be asynchronous. In this sense, the objective of the research was to implement a model of teacher training through virtual courses. These courses are made up of the teaching-learning strategy, pedagogical resources and materials, the learning evaluation system, curricular planning, as well as teacher induction.    Prototypes of the virtual courses were made to be implemented in the future. Also, the methodology carried out in the research, was a first moment, an analysis of the current situation and the proposal to be considered; then to carry out the validation of the model, with experts in educational pedagogy and others in technology oriented education. Likewise, a 10-question instrument was developed for expert validation of the proposed model; resulting in 85.5% acceptance.
Aristotle’s theory of seed: seeking a unified account
Authors: Hu Xinkai
Published: May 2022

Aristotle’s theory of seed has occupied a very important place in the history of ancient embryology and medicine. Previous studies have overemphasized, in light of the APo. II method, Aristotle’s definition of seed as male semen. In this paper, I wish to show that there are at least three independent definitions of seed working in Aristotle’s Generation of Animals: seed as male semen, seed as female menstruation and seed as embryo. Those three definitions are mutually exclusive on the one hand, but on the other hand, they are also capable of being unified into one Aristotelian account, which can help us understand better Aristotle’s theory of seed.

Keywords: Aristotle, theory of seed, animal, generation.
Plato and Hermes in Mani’s Prophetology: a possible adaptation to the theurgical milieu
Authors: Dantas João Paulo , Cornelli Gabriele
Published: May 2022

The aim of this article is to set forth conjectures that are likely to explain the inclusion of Plato and Hermes as heralds of Mani in the testimony of Ephrem of Syria. This incorporation should be set against the background of the Syrian religious milieu, which was influenced by both Hellenistic philosophy and Eastern religious traditions. Therefore, it would be better to seek a religious and philosophical environment wherein Plato and Hermes were associated.
Keywords: Manichaeism, apocalypticism, theurgy, hermetism, Merkabah mysticism, late platonism.
4H-SiC PiN Diode Protected by Narrow Field Rings Investigated by the Micro-OBIC Method
Authors: Planson Dominique , Sonneville Camille , Bevilacqua Pascal , Phung Luong Viet , Asllani Besar , Tournier Dominique , Brosselard Pierre
Published: May 2022

This paper presents micro-OBIC measurements performed at different voltages on two devices protected by narrow field rings. At the surface of the device #1, a polyimide layer was deposited during the fabrication process. On the contrary, passivation layer was removed on device #2. Thanks to the micro-OBIC micrometer spatial resolution and the spot size carefully focused, small gaps in the range of 1 μm can be visible on OBIC profiles. Thus, the variation of the μ-obic accurately reflects the topology of each ring.
Gate Bias Effects on SiC MOSFET Terrestrial-Neutron Single-Event Burnout
Authors: Lichtenwalner Daniel J. , Gajewski Donald A. , Ryu Sei Hyung , Hull Brett , Allen Scott , Palmour John W.
Published: May 2022

Power devices are susceptible to failure by terrestrial neutron single-event burnout (SEB) while in the high-voltage blocking state and above a VDS threshold for that device. Typically, the SEB failure rate is measured at a high blocking voltage, with the source and gate at ground potential. Here the effect of a negative gate bias, commonly applied during MOSFET switching to the blocking state, on the SEB failure rate is examined. It is observed that the SEB failure rate is only weakly dependent on the negative gate bias, because it does not significantly affect the peak field in the drift region where avalanche breakdown is initiated. A negative gate bias of -8VGS in the device blocking state at 1100VDS only results in a 6% increase in the MOSFET SEB failure rate.
Novel Vitrified-Bond Ultra-Fine Grinding Technology for SiC Polishing
Authors: Calvo Ruiz Diego , Sileno Carmine
Published: May 2022

The present paper shows a new fixed abrasive bond-grit formulation aimed for best-in-class, low-cost and high-quality finished SiC wafer surfaces. Grinding wheels manufactured with this technology can accomplish ultra-smooth SiC (Ra = 0.55 nm and TTV < 1 μm) surfaces due to their unique bonding structure and their tailored grit size. Additionally, SiC wafers ground with these wheels exhibit reduced sub-surface crystal damage, mirror-like polished surface and improved wafer geometry while both the grinding forces and the wheel wear are kept low.
Mechanism Governing Surface Roughening of Al Ion Implanted 4H-SiC during Annealing under a C-Cap
Authors: Canino Maria , Mancarella Fulvio , Bonafe Filippo , Corticelli Franco , Albonetti Cristiano , Nipoti Roberta
Published: May 2022

Encapsulating SiC with a carbon layer (C-cap) is a widely used technique to avoid step bunching during post implantation annealing. In this work we propose a mechanism that explains the roughening that the surface unavoidably undergoes during annealing under the C-cap. We investigated the reactions occurring at the interface between 4H-SiC and the C-cap by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy carried out at different stages of the sample processing: just after annealing, after C-cap removal in dry Oxygen, and after cleaning in buffered oxide etch solution. Our observations show that, even though the C-cap roughens for increasing annealing temperature and time, it is not visibly damaged even after 1950 °C 30 min annealing. After the C-cap removal the 4H-SiC surface was covered by a network of clusters that are eventually removed by buffered oxide etch solution. This occurrence suggests that, during the post-implantation annealing, the 4H-SiC surface decomposes and the escaped Si and C atoms are trapped inside the C-cap or at the interface between 4H-SiC and the C-cap. While C clusters are etched off in the dry O2 atmosphere, the Si clusters oxidize and form SiO2 nanoparticles which are finally etched by buffered oxide etch.
Compact Trench Floating Field Rings Termination for 10kV+ Rated SiC n-IGBTs
Authors: Lophitis Neophytos , Gammon Peter Michael , Renz A. Benjamin , Dai Tian Xiang , Tiwari Amit , Trajkovic Tanya , Mawby Philip  Andrew , Udrea Florin , Antoniou Marina
Published: May 2022

This work presents the design methodology and performance of a compact edge termination structure aiming 10kV+ rated Silicon Carbide (SiC) devices. Standard Floating Field Rings (FFRs) for such high voltage rating SiC devices are not favored because they are inefficient in terms of the achievable breakdown voltage as a percentage of the 1D maximum, consume large chip area, require high implantation energies and small gaps between rings which can violate fabrication limits. We show that the implantation of Aluminium at the bottom of carefully positioned trenches can be analogous to deep Aluminium implantation in terms of performance, thus annulling the need for small gaps between rings and MeV ion implantation. We optimize the distribution of trenches by placing them in multiple zones of different expansion coefficient. The proposed multi expansion ratio Trench FFR termination was utilized to terminate the active area of a 10kV rated Punch Through n-IGBT having 0.8 μm p-body and 100 μm, 3×1014 cm-3 drift region. We found the 0.6–0.8 µm to be the most optimum trench depth, achieving over 10 kV within less than 500 μm of termination length.
SiC Mass Commercialization: Present Status and Barriers to Overcome
Authors: Veliadis Victor
Published: May 2022

In an increasingly electrified technology driven world, power electronics is central to the entire clean energy manufacturing economy. Silicon (Si) power devices have dominated power electronics due to their low cost volume production, excellent starting material quality, ease of fabrication, and proven reliability. Although Si power devices continue to improve, they are approaching their operational limits primarily due to their relatively low bandgap, critical electric field, and thermal conductivity that result in high conduction and switching losses, and poor high temperature performance. Silicon Carbide’s (SiC) compelling efficiency and system benefits have led to significant development efforts over the last two decades and today planar and trench MOSFETs, and JFETs are commercially available from several vendors as discrete components or in high power modules in the of 650 V to 1700 V voltage range. High impact application opportunities, where SiC devices are displacing their incumbent Si counterparts, have emerged and include automotive and rail power electronics with reduced losses and reduced cooling requirements; novel data center topologies with reduced cooling loads and higher efficiencies; variable frequency drives for efficient high power electric motors at reduced overall system cost; more efficient, flexible, and reliable grid applications with reduced system footprint; and “more electric aerospace” with weight, volume, and cooling system reductions contributing to energy savings. In particular, SiC insertion in electric vehicles brings major competitive advantages and is a volume application opportunity that can spur manufacturing economies of scale and lower system costs. As SiC continues to grow, the industry is lifting the last barriers to mass commercialization that include higher than Si device cost, relative lack of wafer planarity, the presence of basal plane dislocations, reliability and ruggedness concerns, and the need for a workforce skilled in SiC power technology to keep up with the rising demand. It should be noted that in many applications, insertion of SiC reduces overall system cost compared to Si even though SiC devices can cost 2-3 more than their Si counterparts. This is due to the passive component and cooling system simplifications enabled by the efficient high frequency SiC operation. In this paper, we will review key aspects of SiC technology and discuss overcoming barriers to mass commercialization.
Optical Characterization of 4H-SiC Thick Epitaxial Layer for Particle Detection
Authors: Meli Alessandro , Muoio Annamaria , Reitano Riccardo , Trotta Antonio , Parisi Miriam , Meda Laura , La Via Francesco
Published: May 2022

In the present work a deep characterization of 4H-SiC epi-layer was done. A thick layer was epitaxially grown through chemical vapor deposition (CVD) process in a horizontal hot-wall reactor in order to obtain a 250 microns thick epi-layer. This sample will be used as particle detector in hostile environments such as neutron detection in a nuclear fusion reactor. Raman and Photoluminescence (PL) spectroscopy have been used in order to evaluate the general status of epitaxy and, with the support of the Time Resolved Photoluminescence, also important properties such as carrier lifetime and diffusion length have been evaluated. Carrier lifetime evaluation before and after a thermal oxidation process at 1400° C for 48h was estimated, by considering a lifetime increment after oxidation process, due to the decrease of carbon vacancies. Finally, the influence of stacking fault (SF) defects on carrier lifetime was evaluated observing a decrease of the lifetime for the defects at 430 nm (2.88 eV) for both oxidated and non-oxidated samples.
Observation of Fast Near-Interface Traps in 4H-SiC MOS Capacitors Using Capacitance Voltage Analysis at Cryogenic Temperatures
Authors: Vidarsson A.M. , Nicholls J.R. , Haasmann Daniel , Dimitrijev Sima , Sveinbjörnsson E.Ö.
Published: May 2022

The inversion channel electron mobility in 4H-SiC MOSFETs with NO annealed gate oxides is still well below its theoretical limit. The physical reason behind the reduced mobility is not yet fully established but has for example been attributed to a high density of very fast interface traps close to the conduction band edge. These traps are not detected by high-low CV analysis at room temperature but are observed by conductance spectroscopy at low temperatures. In this study we demonstrate how conventional high-low CV analysis of MOS capacitors at cryogenic temperatures can be applied to detect and quantify these very fast traps.
Failure Analysis of Atmospheric Neutron-Induced Single Event Burnout of a Commercial SiC MOSFET
Authors: Germanicus Rosine Coq , Niskanen Kimmo , Michez Alain , Moultif Niemat , Jouha Wadia , Latry Olivier , Boch Jerôme , Lüders Ulrike , Touboul Antoine D.
Published: May 2022

Dealing with electronic devices for high reliability applications in terrestrial environments, neutron-induced Single Event Effects must be investigated. In this paper, the experimental observation of an atmospheric-like neutron-induced Single Event Burnout (SEB) on a packaged commercial SiC power MOSFET is presented after irradiation at ISIS-ChipIr. The effects of the SEB in the electrical properties of the MOSFET are established, and the SiC damaged zone is observed by scanning electron microscopy. Based on this failure analysis at the die level, the distinct stages during the SEB mechanism can be defined. The sensitive volume where the secondary particle deposited enough energy to trigger the SEB mechanism is identified and located inside the SiC n-drift epitaxial layer near the epitaxial layer/substrate junction.
Highest Quality and Repeatability for Single Wafer 150mm SiC CMP Designed for High Volume Manufacturing
Authors: Yu Sean , Hu Jian Jun , Xu Long Long , Liu Mike , Liu Eulia , Givens John , Leighton Jamie
Published: May 2022

Silicon Carbide (SiC) provides excellent characteristics such as superior thermal conductivity, high carrier mobility and extreme chemical stability in comparison with those of Silicon (Si). SiC is already showing significant device performance benefits in power devices, high performance communication, and LED lighting. However, SiC presents many challenges for wafer surface treatment because of its high hardness and remarkable chemical inertness. Today, mechanical polishing techniques on industrial batch CMP tools are the predominant methods for SiC wafer surface treatment, but material removal rate (MRR), surface defects and wafer flatness control are reaching fundamental limits with increasing wafer diameter. Batch processing typically results in a higher amount of surface scratches and defects, higher wafer to wafer variability, and higher wafer breakage rates. A unique single wafer chemical mechanical polishing (CMP) technique on 150mm n-doped, 4° off-axis, single crystal, 4H-SiC wafers was developed to create a virtually defect-free surface. A polishing head has been designed to manipulate polishing pressures at various zones of the wafer. This capability can modulate the removal thickness at each region on the wafer surface, resulting in a highly uniform wafer profile. Additionally, a CMP slurry has been formulated to maximize MRR from 2μm/hr to over 8.5μm/hr. Potassium permanganate has been selected as an oxidant and aluminum oxide particles as the abrasive. The oxidant concentration and abrasive content along with slurry pH level have also been optimized for ideal chemical and mechanical activity. Scratch-free wafer surfaces are observed with atomic force microscopy (AFM) and bright field (BF) and dark field (DF) inspection techniques. Roughness on the Si face is reduced to below 0.08nm. Total length of surface scratches was reduced to 10mm or less. Industrial metrics of wafer flatness, including total thickness variation (TTV) and local thickness variation (LTV) are modulated and improved. A test run completed on 25-wafers shows an overall 31% improvement of TTV post CMP process.
KPFM - Raman Spectroscopy Coupled Technique for the Characterization of Wide Bandgap Semiconductor Devices
Authors: Bercu Nicolas , Lazar Mihai , Simonetti Olivier , Adam Pierre Michel , Brouillard Mélanie , Giraudet Louis
Published: May 2022

A non-destructive technique for the characterization of the doped regions inside wide bandgap (WBG) semiconductor structures of power devices is presented. It consists in local measurements of the surface potential by Kelvin Probe Force Microscopy (KPFM) coupled to micro-Raman spectroscopy. The combined experiments allow to visualize the space charge extent of the doped region using the near-field mapping and to estimate its dopant concentration using the Raman spectroscopy. The technique has been successfully applied for the characterization of a WBG SiC (silicon carbide) device.
Monolithic Integration of Graphene in SiC Radiation Sensors for Harsh-Environment Applications
Authors: Otero Ugobono Sofía , Rafi J.M. , Godignon Philippe , Pellegrini G. , Rius Gemma , Jiménez Ramos M.C. , García López J. , García Osuna A.
Published: May 2022

Due to their low leakage current, low noise levels, high thermal conductivity, and potential radiation hardness, SiC devices offer various advantages over Si devices in certain applications. As a result, they are being considered for operation in harsh environments, such as plasma diagnostic systems in future nuclear fusion reactors or in high energy physics applications. We report on relevant results of the GRACE project, which seeks to deliver a new generation of SiC sensors with graphene-enhanced contacts. Such devices are aimed to be radiation-hard and functional at high temperatures. The work presented in this paper focuses on the optimisation of the electrical contacts, along with the electrical characterisation and radiation-tolerance assessment of the first sensor prototypes produced.
Aluminum Activation in 4H-SiC Measured on Laterally Contacted MOS Capacitors with a Buried Current-Spreading Layer
Authors: Mletschnig Kristijan Luka , Rommel Mathias , Pobegen Gregor , Schustereder Werner , Pichler Peter
Published: May 2022

The excellent material properties of the wide band gap semiconductor SiC are accompanied by challenges in device processing. Of particular importance is the incomplete activation of implanted Al acceptors after high-temperature annealing. In this work, we present a novel approach in applying the differential-capacitance method to lateral MOS capacitors, where systematic errors in its characterization are reduced by introducing a buried current-spreading layer. We find that the implantation of an additional current-spreading layer significantly reduces series resistance effects and enables a reliable capacitance-voltage measurement of low dopant concentrations of p-type wells in n-type epitaxial layers. The measurement of an Al box-like profile implanted at 500 °C and resulting in a doping concentration of 3·1017 cm-3 shows full activation after annealing at 1800 °C for 30 minutes.
Charge Trapping Mechanisms in Nitridated SiO2/ 4H-SiC MOSFET Interfaces: Threshold Voltage Instability and Interface Chemistry
Authors: Fiorenza Patrick , Bongiorno Corrado , Messina A. , Saggio Mario , Giannazzo Filippo , Roccaforte Fabrizio
Published: May 2022

Silicon dioxide (SiO2) layers deposited on 4H-SiC and subjected to different post deposition annealing (PDA) in NO and N2O were studied to identify the key factors influencing the channel mobility and threshold voltage stability in lateral implanted 4H-SiC MOSFETs. Cyclic gate bias stress measurements allowed to separate the contributions of interface states (Nit) and near interface oxide traps (NIOTs) in the two oxides. The reduction of these traps in the NO annealed sample is due to the lower amounts of sub-stoichiometric silicon oxide (~1nm) and carbon-related defects (<1nm) at the interface, as could be demonstrated by Electron Energy Loss Spectroscopy. The experimental results indicate that limiting the SiC re-oxidation during post-deposition annealing in MOSFET technology is a key factor to improve the mobility and threshold voltage stability.
Robustness of Semi-Superjunction 4H-SiC Power DMOSFETs to Single-Event Burnout from Heavy Ion Bombardment
Authors: McPherson Joseph A. , Woodworth Andrew A. , Chow T. Paul , Ji Wei
Published: May 2022

We compare the failure mechanism and performance of a silicon carbide (SiC) semi-superjunction (semi-SJ) power DMOSFET against pure SJ and conventional DMOSFET when struck by a single heavy ion. The Single-Event Burnout (SEB) failure mechanism was identified as the thermal runaway from second breakdown resulting in mesoplasma formation. The semi-SJ design shifts the mesoplasma location from the drift/substrate interface seen in the control device structures to a location along the center of the P-pillar and closer towards the DMOSFET surface, thus significantly improving the SEB threshold voltage (VSEB). The VSEB varies with pillar width and ratio of pillar thickness to drift layer thickness. A maximum value of VSEB is reached when the pillar to drift layer ratio is 0.9 and the pillar width is 2.4 μm. The semi-SJ SEB/breakdown voltage ratio is 100% and 13% higher than the pure SJ and conventional DMOSFET, respectively. Using a new Figure of Merit (FoM), which accounts for the tradeoff between VSEB and on-state performance, we find that the SiC semi-SJ DMOSFET achieves a FoM that is 1.8 and 8 times higher than SJ and conventional DMOSFET, respectively, making the semi-SJ a competitive candidate for radiation hardened applications.
Design and Methodology of Silicon Carbide High Voltage Termination Extension for Small Area BJTs
Authors: Ammar Ali , Phung Luong Viet , Planson Dominique , Morel Hervé , Sonneville Camille
Published: May 2022

An optimized termination extension tutorial is reported for a small area (≈ 1mm2 ) 4H-SiC NPN BJT. The extension system is based on a parametric JTE with isolation rings. Additional aspects such as (1) MESA angle, (2) relieving electric field on the base-drift junction, and (3) blocking the electric field from reaching border structure are investigated. A breakdown voltage greater than 10 kV is recorded, when drift region is n-doped to 8x1014 cm-3.
Silicon Carbide - Graphene Nano-Gratings on 4H and 6H Semi-Insulating SiC
Authors: Mathew Sobin , Lebedev Sergey P. , Lebedev Alexander A. , Hähnlein Bernd , Stauffenberg J. , Manske E. , Pezoldt Joerg
Published: May 2022

A technical methodology of fabrication of hierarchically scaled multitude graphene nanogratings with varying pitches ranging from the micrometer down to sub 40 nm scale combined with sub 10 nm step heights on 4H and 6H semi-insulating SiC for length scale measurements is proposed. The nanogratings were fabricated using electron-beam lithography combined with dry etching of graphene, incorporating a standard semiconductor processing technology. A scientific evaluation of critical dimension, etching step heights, and surface characterization of graphene nanograting on both polytypes were compared and evaluated.
Applicability of a Flat-Bed Birefringence Setup for the Determination of Threading Dislocations of Silicon Carbide Wafers
Authors: Steiner Johannes , Nguyen Binh Duong , Roder Melissa , Danilewsky Andreas N. , Sandfeld Stefan , Wellmann Peter J.
Published: May 2022

Screw-type dislocations like micropipes (MP) and threading screw dislocations (TSD) are prohibiting the function or at least diminishing the efficiency of electronic devices based on silicon carbide (SiC). Therefore, it is essential to characterize wafers in an efficient and fast manner. Molten potassium hydroxide (KOH) etching or white-beam X-ray topography (SWXRT) are either destructive or not economically viable for an in-depth characterization of every wafer of one SiC crystal. Birefringence microscopy is being utilized as a fast and non-destructive characterization method. Instead of microscopic setups, commercially available flat-bed scanners equipped with crossed polarizer foils can be used for fast large-area scans. This work investigates the feasibility of such a setup regarding the detection rate of MPs and TSDs. The results of a full-wafer mapping are compared with birefringence microscopy and KOH etching. In the investigated sample clusters of MPs caused by a polytype switch in the beginning of the growth could be identified by both birefringence microscopy and the flat-bed scanner setup, as well as small angle grain boundaries and TED arrays. However, the resolution of the scanner was not sufficient to identify TSDs. Nevertheless the setup proves to be an easy-to-setup and cheap characterization method, able to quickly identify defect clusters in 4H-SiC wafers.
Electrothermal Modelling and Measurements of Parallel-Connected VTH Mismatched SiC MOSFETs under Inductive Load Switching
Authors: Mendy Simon , Wu Rui Zhu , Ortiz-Gonzalez Jose , Alatise Olayiwola
Published: May 2022

In high current applications that use several parallel-connected SiC MOSFETs (e.g., automotive traction inverters), optimal current sharing is integral to overall system reliability. Threshold voltage (VTH) variation in SiC MOSFETs is a prevalent reliability issue that can cause current mismatch in parallel-connected devices. Using experimental measurements and compact modelling, a technique has been developed for characterising the impact of VTH variation in up to 8 parallel-connected SiC MOSFETs. This model can predict the allowable VTH variation for optimal current sharing. It can also be used to evaluate the impact of other parameters, including gate driver synchronisation, on current sharing in parallel devices.
New developments in the treatment of cutaneous leishmaniasis
Authors: Dinc Rasit
Published: May 2022

Leishmaniasis, including the cutaneous form, poses an important public health threat around the world, while no vaccine is currently available against any form of leishmaniasis. The drugs used in the first line treatment of cutaneous leishmaniasis (CL) are commonly pentavalent antimonials despite their toxicities, long-term treatment duration and increasing resistance rates. Other alternatives are amphotericin B, pentamidine, miltefosine and paromomycine. Movement of the population, especially in endemic regions, increases the spread of the parasite and affectes the distribution of causative species, which requires re-evaluation the treatment regimen. Extensive researches are carried out on the treatment of leishmaniasis. The immunotherapeutic and targeted therapeutic approaches, formulations of carrier-loaded active drugs, local thermotherapeutic applications, the combination of antileishmanial drugs/compounds, the use of new synthetic and natural products are promising therapeutic options in the future. Herein, the author reviews the potential treatment modalities of CL with a brief overview of current treatments in the light of ongoing studies around the world.
Ficus carica hairy roots
Authors: Amani Shahla , Khademvatan Shahram , Mohebodini Mehdi , Jafari Morad , Kumar Vinod
Published: May 2022

Objective:

To investigate the biochemical capacity, and in vitro inhibitory effects of hairy roots from two cultivars of Ficus carica L. (Sabz and Siah) on Leishmania major promastigotes and amastigotes.

Methods:

In the hairy roots, the activity of antioxidant enzymes compared to normal leaves and roots, and the presence of some phenolic compounds in comparison with fruits were investigated. The IC50 values of hairy roots in promastigotes was determined by tetrazolium-dye 3-(4, 5-dimethylthiazol-2- yl)-2, 5-diphenyltetrazolium bromide and trypan blue assays. By calculating the infectivity index of peripheral blood mononuclear cells (PBMCs), the leishmanicidal activity (IC50 values) of hairy roots for amastigotes was estimated. The effects of hairy roots (IC50 values) treatment on the levels of IFN-γ and iNOS expression, intracellular reactive oxygen species, and iNOS protein expression in infected-PBMCs were determined.

Results:

Based on antioxidant enzyme assays and high performance liquid chromatography analysis, hairy roots exhibited high antioxidant capacity and contained high levels of phenolic compounds. According to the results of tetrazolium-dye 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and trypan blue assays, the hairy root extracts of both cultivars showed considerable dose-dependent inhibitory effects against Leishmania major promastigotes. Depending on the concentration and exposure time, treatment of infected-PBMCs with hairy root extracts caused the generation of a significant reactive oxygen species, up- regulation of IFN-γ and iNOS genes expression, and high value of iNOS protein compared to controls.

Conclusions:

The findings of this study suggest that the hairy roots of Ficus carica can be considered as a promising natural source of antileishmanial agents.
Strengthening quality management system
Authors: Shrivastava Manisha , Shah Nehal , Navaid Seema , Mishra Shweta
Published: May 2022

OBJECTIVES:

The objective of this study was to assess the changes in knowledge concerning quality management system (QMS) among the participants before and after attending a QMS training.

METHODS:

After obtaining the ethical approval, a retrospective study was designed to evaluate the effectiveness of QMS. Fifty participants from district blood banks of three different states participated in the study organized at two different periods. After obtaining informed consent, the participants were subjected to set of questionnaire containing 45 questions (35 multiple choice and 10 subjective questions) as pretest on quality standards and were again subjected to posttest questionnaire containing the same set of questions after 5 days of workshop. Twenty minutes were granted to solve the questions. Each question was given one mark. There was no negative marking. An assessment of knowledge gained during training was evaluated by comparing the scores of pre- and post-assessment.

RESULTS:

Of the total 50 delegates, 29 were trained in the month of July (Training I) and 21 were trained in the month of November (Training II). There were 96% (n = 48) males and 4% (n = 2) females. In both the training sessions, that is, Training I and II, the mean scores of objective questions in pretest were 13.629 ± 6.58 and 9.34 ± 5.74, and after the training, the posttest scores increased significantly to 17.77 ± 7.05 and 14.34 ± 7.09, respectively. Paired Student's t-test was applied which showed statistically significant increment in knowledge (P = 0.001).

CONCLUSIONS:

There was a significant positive change in the knowledge of the participants after attending QMS workshop.
A case report of a rare entity
Authors: Muthiah Shanmugam , Sivaramamoorthy Vijay Kumar , Natrajan Muthukumar
Published: May 2022

Congenital spinal dermal sinus tract is a rare entity and is usually solitary. Multiple dermal sinus tracts in a child are extremely rare; so far, only five cases have been published in the English literature to our knowledge. We report a case of double dermal sinus tracts with double intradural dermoid, and such a combination has not been reported. Meticulous excision of both dermal sinus tracts and intradural dermoid resulted in complete recovery. We present this rare entity and review the literature.
Pharmacogenomics of Adrenergic Receptors from Bench to Bedside
Authors: Howaidi Jude , Lababidi Hani MS
Published: May 2022

Distinctions in the DNA sequence of the genes pertaining to α and β adrenergic receptors can result in genetic polymorphisms. These variations can potentially impact response to treatment with adrenergic agonists and antagonists that likely warrant medical intervention. Pharmacogenomics is conceptualized as “the right drug to the right patient,” which implies that pharmacogenomics is entirely personalized. Given that adrenoreceptors play a fundamental role in regards to the pharmacogenetic interaction between catecholamines with α and β adrenergic receptors, it is, therefore, pivotal to highlight and further analyze variants amongst adrenergic receptors to improve the management of diseases pertaining to catecholamine dysfunction. In this review, we highlight the pharmacogenomics of adrenergic receptors and their potential clinical implications in critical care. It is evident that there are several variants associated with the adrenergic receptor alpha 1A (ADRA1A), adrenergic receptor alpha 2A (ADRA2A), adrenergic receptor beta-1 (ADRB1), adrenergic receptor beta-2 genes for α and β adrenergic receptors that were observed among different populations and ethnic groups including the Arg347Cys and Arg389Gly in ADRA1A and ADRB1, respectively. These polymorphisms have resulted in interindividual variability in drug responses for epinephrine, dexmedetomidine, and salbutamol, which concludes that pharmacogenomics of adrenergic receptors have proven immense variability in candidate genes amongst populations that lead to different drug responses.
Respiratory Intensive Care Unit
Authors: Alharbi Abdullah Rashed , Nadama Ahmed Rufai , Alsergani Reem , Alwael Haifa , Alshathri Reem , Alshaibi Amal , Alshabib Norah
Published: May 2022

Background:

With the COVID-19 pandemic having a significant negative impact on the health-care systems globally, different models of respiratory intermediate care units were shown to play a vital role in the management of COVID-19 patients, especially those with impaired oxygenation. The present study demonstrates that respiratory intermediate care units were helpful in reducing health-care cost and acting as a backup for intensive care units (ICUs) in Saudi Arabia.

Design and Setting:

This is a retrospective study that was carried out in King Saud University Medical City, Riyadh, Saudi Arabia, between June 15, 2020, and August 7, 2020. The study team collected information from patients' records. The data collected comprised patient's demographic information, admission site, admission criteria, and length of hospital stay. Descriptive and comparative analyses were carried out through the SPSS version 26.

Results:

Eighty-one patients were eligible for inclusion: 67.9% were male, 58% were above 50 years old, and similar proportions were overweight. Chronic kidney disease was the most commonly occurring comorbidity (23.5%), whereas only three patients had hypertension, and a similar number had some form of immunosuppression. In addition, 44.4% of patients were admitted through COVID wards. The mean length of hospital stay was 11 ± 5 days, with 54.3% of patients staying for more than 10 days. About 97.5% of the patients were transferred to the general medical COVID-19 ward, whereas only 2.5% were admitted to ICU. The percentage of high-flow oxygen either high-flow nasal cannula or noninvasive ventilator was 66.2 ± 15.7%. About 27.2% of the patients required oxygenation through a simple standard interface such as a mask or nasal cannula. There was no significant difference among age groups and different body mass index categories in terms of hospitalization course and oxygenation. Females used noninvasive ventilation (P = 0.008) more than males.

Conclusion:

Females are more prone to higher oxygenation needs compared to males with COVID-19 infections. Respiratory care units can reduce the number of females who need ICU admissions for noninvasive ventilation.
Processing the structure of documents: Logical Layout Analysis of historical newspapers in French
Authors: Gutehrlé Nicolas , Atanassova Iana
Published: May 2022

Background. In recent years, libraries and archives led important
digitisation campaigns that opened the access to vast collections of historical
documents. While such documents are often available as XML ALTO documents, they
lack information about their logical structure. In this paper, we address the
problem of Logical Layout Analysis applied to historical documents in French.
We propose a rule-based method, that we evaluate and compare with two
Machine-Learning models, namely RIPPER and Gradient Boosting. Our data set
contains French newspapers, periodicals and magazines, published in the first
half of the twentieth century in the Franche-Comt\'e Region. Results. Our
rule-based system outperforms the two other models in nearly all evaluations.
It has especially better Recall results, indicating that our system covers more
types of every logical label than the other two models. When comparing RIPPER
with Gradient Boosting, we can observe that Gradient Boosting has better
Precision scores but RIPPER has better Recall scores. Conclusions. The
evaluation shows that our system outperforms the two Machine Learning models,
and provides significantly higher Recall. It also confirms that our system can
be used to produce annotated data sets that are large enough to envisage
Machine Learning or Deep Learning approaches for the task of Logical Layout
Analysis. Combining rules and Machine Learning models into hybrid systems could
potentially provide even better performances. Furthermore, as the layout in
historical documents evolves rapidly, one possible solution to overcome this
problem would be to apply Rule Learning algorithms to bootstrap rule sets
adapted to different publication periods.
Tractable Combinations of Temporal CSPs
Authors: Bodirsky Manuel , Greiner Johannes , Rydval Jakub
Published: May 2022

The constraint satisfaction problem (CSP) of a first-order theory T is the
computational problem of deciding whether a given conjunction of atomic
formulas is satisfiable in some model of T. We study the computational
complexity of CSP$(T_1 \cup T_2)$ where $T_1$ and $T_2$ are theories with
disjoint finite relational signatures. We prove that if $T_1$ and $T_2$ are the
theories of temporal structures, i.e., structures where all relations have a
first-order definition in $(Q;<)$, then CSP$(T_1 \cup T_2)$ is in P or
NP-complete. To this end we prove a purely algebraic statement about the
structure of the lattice of locally closed clones over the domain $Q$ that
contain Aut$(Q;<)$.