bluuebunny/crossref_metadata_2025 huggingface dataset:
How patients with COVID-19 managed the disease at home during the first wave in Spain: a cross-sectional study
Authors: Romay-Barja María , Pascual-Carrasco Mario , De Tena-Dávila María José , Falcón María , Rodriguez-Blazquez Carmen , Forjaz Maria João , Ayala Alba , Molina-de la Fuente Irene , Burgos Alfredo , Muñoz Adolfo , Benito Agustin
Published: May 2021

Objective

Most patients with mild COVID-19 had to stay at home trying to implement an optimal quarantine. The aim of this study was to describe the COVID-19 cases during the first wave of the pandemic in Spain, how they managed the disease at home, focusing on differences by age, as well as differences in knowledge, attitudes and preventive practices, compared with the uninfected population.

Design

An online survey was used to conduct a cross-sectional study of individuals who were 14 years or older living in Spain during the COVID-19 lockdown. The main variable was a COVID-19 case. Logistic regression models for COVID-19 cases were obtained using a backward stepwise procedure to assess the association between social variables, disease knowledge, attitudes, prevention practices and emotional impact.

Results

3398 people completed the survey. Participants’ mean age was 49.6 (SD=14.3). COVID-19 was significantly more prevalent among married people (5.3%) and those currently doing an on-site work (8.7%). Most of the COVID-19 cases stayed at home (84.0%) during the episode. There were significant age-based differences with regard to self-isolation conditions at home during the disease. COVID-19 cases showed better attitudes, practices and knowledge about disease symptoms and transmission than the uninfected population. COVID-19 cases also felt more depressed (adjusted OR: 3.46, 95% CI 1.45 to 8.26) and had better preventive behaviour than the uninfected population, such as always wearing a mask outside the home (adjusted OR 1.58, 95% CI 1.06 to 2.30).

Conclusion

COVID-19 cases found it difficult to comply with recommended home self-isolation conditions, with differences by age group. COVID-19 had an important impact on care dependency in non-hospitalised patients, who were mostly dependent on their families for care. It is necessary to reinforce social and health services and to be ready to meet the care needs of populations during the different waves or in future epidemics.
Primary care physician’s (PCP) perceived value of patient-reported outcomes (PROs) in clinical practice: a mixed methods study
Authors: Mou Danny , Horn Daniel M , Heng Marilyn , Castillo-Angeles Manuel , Ladin Keren , Frendl Daniel , Kaur Manraj , del Carmen Marcela , Sequist Thomas Dean , Sisodia Rachel C
Published: May 2021

Background

Patient-reported outcomes (PROs) can promote patient engagement, shared-decision making and improve the overall experience of care. However, PRO integration in the primary care clinical setting is limited. Exploring the perspectives of primary care physicians (PCPs) on PROs is key to understanding how they are being used in the clinical setting. We sought to elucidate this clinical perspective at one of the largest US health systems that has integrated a wide range of PROs into routine primary care.

Methods

Mixed methods study with both anonymous online surveys and in-person qualitative semistructured interviews conducted with PCPs to understand their clinical perspectives on the applications of the existing PROs. PCPs from the 19 affiliated clinics were prompted to complete the survey. Interviewed PCPs were selected via a combination of random and purposive selection from the PCP directory.

Results

Of 172 PCPs, 117 (68%) completed the online survey and 28 completed semistructured interviews. Most PCPs (77%) reviewed PRO responses with their patients. PCPs endorsed that PROs improve clinic efficiency and clinical management. However, PCPs have heterogeneous perspectives on the relevance of PROs in clinical practice, likely due to variations in clinic practice. For specific PRO instruments, PCPs reported anxiety and depression screening PROs to be most helpful. PCPs felt that PROs assisted with completing screening questions that are required by regulatory bodies. Barriers to using PROs include poor user-interface for both clinicians and patients and inadequate training.

Conclusions

Most PCPs regularly use PRO data though there are mixed opinions about their clinical relevance. An adaptable, user-friendly PRO system has the potential to have meaningful clinical applications in primary care.
Improving detection and management of familial hypercholesterolaemia in Australian general practice
Authors: Brett Tom , Chan Dick C , Radford Jan , Heal Clare , Gill Gerard , Hespe Charlotte , Vargas-Garcia Cristian , Condon Carmen , Sheil Barbara , Li Ian W , Sullivan David R , Vickery Alistair W , Pang Jing , Arnold-Reed Diane E , Watts Gerald F
Published: May 2021

Objective

Familial hypercholesterolaemia (FH) is characterised by elevated low-density lipoprotein (LDL)-cholesterol and increased risk of cardiovascular disease. However, FH remains substantially underdiagnosed and undertreated. We employed a two-stage pragmatic approach to identify and manage patients with FH in primary healthcare.

Methods

Medical records for 232 139 patients who attended 15 general practices at least once in the previous 2 years across five Australian States were first screened for potential risk of FH using an electronic tool (TARB-Ex) and confirmed by general practitioner (GP) clinical assessment based on phenotypic Dutch Lipid Clinic Network Criteria (DLCNC) score. Follow-up GP consultation and management was provided for patients with phenotypic FH.

Results

A total of 1843 patients were identified by TARB-Ex as at potential risk of FH (DLCNC score ≥5). After GP medical record review, 900 of these patients (49%) were confirmed with DLCNC score ≥5 and classified as high-risk of FH. From 556 patients subsequently clinically assessed by GPs, 147 (26%) were diagnosed with phenotypic FH (DLCNC score >6). Follow-up GP consultation and management for 77 patients resulted in a significant reduction in LDL-cholesterol (−16%, p<0.01). A higher proportion of these patients attained the treatment target of 50% reduction in LDL-cholesterol (74% vs 62%, p<0.001) and absolute levels of LDL-cholesterol goals compared with baseline (26% vs 12%, p<0.05).

Conclusions

A pragmatic approach integrating electronic medical record tools and clinical GP follow-up consultation is a feasible method to identify and better manage patients with FH in the primary healthcare setting.

Trial registration number

12616000630415.
Role of serum adropin measurement in the assessment of insulin resistance in obesity
Authors: Erman Hande , Ozdemir Ali , Sitar Mustafa Erinc , Cetin Seher Irem , Boyuk Banu
Published: May 2021

Obesity has recently been mentioned as a metabolic pandemic in developed and developing countries and is an important known risk factor for type 2 diabetes and cardiovascular diseases. The main mechanism responsible for obesity is insulin resistance. Adropin is a peptide-structured regulatory hormone that is suggested to play a role in insulin resistance and metabolic regulation. We aimed to evaluate the associations of serum adropin with insulin resistance and clarify the factors affecting serum adropin concentrations. The study included 50 obese patients and 22 healthy controls. Patients with chronic disease and drug use history were excluded. Serum adropin and other metabolic parameters were obtained after overnight fasting. ELISA was used to measure serum adropin concentrations. The homeostatic model assessment-insulin resistance (HOMA-IR) index was used to calculate insulin resistance. Insulin resistance was defined as HOMA-IR >2.5. Serum adropin values were found to be low in the obese otherwise healthy patient group (p<0.001). Linear regression analysis revealed that age, body mass index (BMI), waist circumference (WC), high-density lipoprotein cholesterol, fasting glucose, and HOMA-IR affect serum adropin level. In multiple regression analysis, age is the most significant factor affecting serum adropin concentration. Serum adropin concentrations were negatively correlated with BMI, WC, diastolic blood pressure, fasting glucose, and insulin. Serum adropin concentrations were low in obese patients and the optimum cut-off point for adropin to indicate HOMA-IR at 2.5 is 216.7 ng/L. The findings suggest that serum adropin may contribute to the regulation of glycolipid metabolism and insulin resistance in obese patients.
Summer hypoxia in Bohai Sea caused by changes in phytoplankton community
Authors: Wei Hao , Zhao Liang , Zhang Haiyan , Lu Youyu , Yang Wei , Song Guisheng
Published: May 2021

In the deep central part of the Bohai Sea off the coast of northern China, long-term observations show significantly lower dissolved oxygen (DO) concentration near the bottom in summer during 2006–2018 than during 1978–2005. The decrease in bottom DO is closely linked to changes in phytoplankton community driven by nutrient structure changes in the water column. From literature review, observations in the phytoplankton community structure indicate an increase in the abundant proportion of dinoflagellate to diatom and miniaturization since the 21st century. The new dominate species of dinoflagel-late and the pico- and nano-celled algae detritus, with slow sinking rate and long residence time, favor the efficient oxygen consumption in the water column and lead to oxygen depletion enhancement and DO concentration decrease after 2006. Analyses also suggest that water temperature, stratification, and resuspension of sediment play less significant roles in long-term variations of DO. The linkage of hypoxia formation to changes of phytoplankton community answers why hypoxia in the Bohai Sea started to occur in the recent decade while eutrophication began since the 1980s. The identified new mechanism of hypoxia formation may be applicable to other coastal seas where eutrophication has led to changes in the phytoplankton community, and should be considered in biogeochemical models.
Increased Arctic climate extremes constrain expected higher plant reproductive success in a warmer climate
Authors: Panchen Zoe A. , Frei Esther R. , Henry Greg H.R.
Published: May 2021

The low reproductive success of Arctic plants is predicted to increase as the climate warms. However, climate extremes add complexity to these predictions. In the extremely cold year of 2018, multiple Arctic trophic levels experienced reproductive failure. We analysed a unique long-term record of seed viability from experimentally warmed and ambient plots at Alexandra Fiord, Ellesmere Island, which has been running since 1992 and included 2018 and the extremely warm year of 2019. Positive and negative July temperature anomalies and summer temperatures have increased significantly by 0.5, −0.3, and 0.4 °C/decade since 1977, respectively, resulting in greater extremes and increased inter-annual variation. Seed viability of some species has increased with climate warming. Across years, seed viability of woody species was consistently higher in warmed than ambient plots while the opposite was true for forbs. In 2018, seed viability of woody species in ambient plots was significantly lower than normal but comparable with past years for forb species. Not all species returned to normal seed viability levels in 2019. Our study highlights the potential for greater sexual reproductive failure in tundra plants with increasing climate extremes. We suggest that poor seed viability of woody species in cold years could constrain shrub recruitment and may aid forb species establishment on bare tundra.
Long-term natural dynamics of an alpine lichen heath in the Teberda State Biosphere Reserve, northwestern Caucasus
Authors: Elumeeva Tatiana G. , Tekeev Dzhamal K. , Bairamkulova Svetlana U. , Onipchenko Vladimir G.
Published: May 2021

The alpine vegetation of Europe and the Caucasus has experienced substantial changes due to climate warming and reduced grazing. Exposed ridge communities, such as alpine heaths, are presumed to be less vulnerable to such processes. Herein, we analyze long-term dynamics (over 37 years) of an alpine lichen heath in the Teberda State Biosphere Reserve, Karachaevo-Cherkessian Republic, Russia. We counted the shoots of all vascular plants present on permanent plots. Autocorrelated linear regressions, a non-metric multidimensional scaling ordination, and a fourth-corner analysis were applied to characterize the relationships between shoot numbers, climate variables (temperatures and precipitation), functional traits, and species strategies. Nine species, including dominant Festuca ovina L. and Antennaria dioica (L.) Gaertn., increased their abundances, whereas Carex spp. were observed to decrease. The overall dynamics were mainly driven by increasing mean temperatures during the growing season (July and August). None of the changes observed in the selected traits were correlated with increasing or decreasing numbers of species; however, some traits (plant height, specific root length, specific leaf area, and leaf carbon content) were potentially associated with climate variables. The observed dynamics suggested an overall increase in the abundance of herbaceous plants. Generally, our results support “greening” effects in tundra and alpine biomes.
Renormalization scheme and mass scale independence
Authors: Chishtie F.A. , McKeon D.G.C.
Published: May 2021

We demonstrate that in the mass-independent renormalization scheme, the renormalization group equations associated with the unphysical parameters that characterize the renormalization scheme and the mass scale leads to summation that results in a cancellation between the implicit and explicit dependence on these parameters. The resulting perturbative expansion is consequently independent of these arbitrary parameters. We illustrate this by considering R, the cross section for e+e– → hadrons.
The M-fractional improved perturbed nonlinear Schrödinger equation: Optical solitons and modulation instability analysis
Authors: Khalil Eied M. , Sulaiman T. A. , Yusuf Abdullahi , Inc Mustafa
Published: May 2021

In order to obtain some novel analytical solutions for fractional improved nonlinear Schrodinger equation with perturbation, the polynomial expansion, simplest equation and extended sine-Gordon expansion schemes are utilized. A collection of different types of solitons are reported with a physical and important perspective, containing optical dark solitons. The methods reveal the solutions in a structure of rapidly converging series. This research highlights additional important features of the methods being considered. In addition, the modulation instability analysis is carried out to discuss the stability analysis of the solutions reached, and the movement role of the waves is examined, which affirms that all the established solutions are exact and stable.
Tobacco stalk-derived carbon prepared by one-step molten salt carbonization for supercapacitor
Authors: Liu Yuxuan , Cheng Xinhua , Zhang Shenghui
Published: May 2021

High-performance capacitive carbon materials, derived from tobacco stalk, were prepared by a one-step carbonization process in molten carbonate. Owing to the high specific surface area (SSA) (1165.9 m2 g[Formula: see text] and heteroatom doping by the activation effect of molten salt medium for 3 h, the as-obtained carbon material with hierarchically porous structure exhibits an ideal capacitive property with delivering specific capacitances of 219.8, 188.0, 176.4, and 168.4 F g[Formula: see text] at 0.2, 0.5, 1, and 2 A g[Formula: see text], respectively, acceptable rate performance with 76.6% capacitance retention in range of 0.2–2 A g[Formula: see text], and good cyclic stability with 93% capacitance retention after 3000 charge–discharge cycles at 1 A g[Formula: see text], as well as energy density of 30.5 Wh kg[Formula: see text] at 0.2 A g[Formula: see text] and power density of 989.6 W kg[Formula: see text] at 2 A g[Formula: see text] in 1 mol L[Formula: see text] H2SO4 aqueous solution using a three-electrode system. Moreover, it delivers specific capacitances of 143.3, 140.2, 137.4, and 134.3 F g[Formula: see text] at 0.2, 0.5, 1, and 2 A g[Formula: see text], respectively, and excellent rate performance with 93.7% capacitance retention in range of 0.2–2 A g[Formula: see text], as well as energy density of 4.9 Wh kg[Formula: see text] at 0.2 A g[Formula: see text] and power density of 488.6 W kg[Formula: see text] at 2 A g[Formula: see text] in 6 mol L[Formula: see text] KOH aqueous solution using a symmetrical two-electrode system. The correlation between hierarchically porous structure with heteroatom doping and capacitive performance is also discussed.
Review of "Rhetoric technology and the virtues by Jared S. Colton and Steve Holmes," Colton, J. S., & Holmes, S. (2018). Rhetoric, technology, and the virtues. Utah State University Press
Authors: Vance Bremen , Malone Lauren
Published: May 2021

Discussions about communication and education have become focused on social justice in recent years, and with good reason. Social justice is at the forefront of many aspects of our daily lives in news, education, and even entertainment. As digital rhetoricians and educators, we have found ourselves looking for ways to work at the intersections of our field and social justice to improve both learning experiences and networked communication in non-academic contexts. This work is both timely and needed, as the hierarchies and inequities experienced in "real life" often translate to, and are amplified by, networked and digital forms of engagement. Fortunately,
Rhetoric, Technology, and the Virtues
offers an insightful and practical discussion about ethical frameworks that contribute to our understanding of digital social justice. Colton and Holmes persuasively argue for the value of Aristotle's virtue ethics, especially the idea of
hexis
, as a model for empowering students, educators, and others to enact digital social justice. As they explain, Aristotle identified virtues "such as patience, courage, temperance, and liberality" that contribute to ethical behavior and "are developed not solely through reason or by learning rules but through practice of the emotional and social skills that enable us within a community to work toward...human flourishing and general well-being" (p. 32). An essential part of Aristotle's framework is
hexis
, a person's disposition that has been crafted through habit and repeated practice (p. 11). Colton and Holmes effectively demonstrate how a virtue ethics framework can empower individuals to take ownership of the ethical implications of digital practices. Throughout the book, Colton and Holmes address familiar topics in digital rhetoric ranging from captioning (pp. 3--5, 49--73), remixing (pp. 74--94), and issues inherent in online activism (pp. 95--126).
Deep mapping for environmental communication design
Authors: Butts Shannon , Jones Madison
Published: May 2021

This article shares lessons from designing EcoTour, a multimedia environmental advocacy project in a state park, and it describes theoretical, practical, and pedagogical connections between locative media and community-engaged design. While maps can help share information about places, people, and change, they also limit how we visualize complex stories. Using deep mapping, and blending augmented reality with digital maps, EcoTour helps people understand big problems like climate change within the context of their local community. This article demonstrates the rhetorical potential of community-engaged design strategies to affect users, prompt action, and create more democratic discourse in environmental communication.
Predicting Visual Search Task Success from Eye Gaze Data as a Basis for User-Adaptive Information Visualization Systems
Authors: Spiller Moritz , Liu Ying-Hsang , Hossain Md Zakir , Gedeon Tom , Geissler Julia , Nürnberger Andreas
Published: May 2021

Information visualizations are an efficient means to support the users in understanding large amounts of complex, interconnected data; user comprehension, however, depends on individual factors such as their cognitive abilities. The research literature provides evidence that user-adaptive information visualizations positively impact the users’ performance in visualization tasks. This study attempts to contribute toward the development of a computational model to predict the users’ success in visual search tasks from eye gaze data and thereby drive such user-adaptive systems. State-of-the-art deep learning models for time series classification have been trained on sequential eye gaze data obtained from 40 study participants’ interaction with a circular and an organizational graph. The results suggest that such models yield higher accuracy than a baseline classifier and previously used models for this purpose. In particular, a Multivariate Long Short Term Memory Fully Convolutional Network shows encouraging performance for its use in online user-adaptive systems. Given this finding, such a computational model can infer the users’ need for support during interaction with a graph and trigger appropriate interventions in user-adaptive information visualization systems. This facilitates the design of such systems since further interaction data like mouse clicks is not required.
Genetic Improvement of Routing Protocols for Delay Tolerant Networks
Authors: Lorandi Michela , Custode Leonardo Lucio , Iacca Giovanni
Published: May 2021

Routing plays a fundamental role in network applications, but it is especially challenging in Delay Tolerant Networks (DTNs). These are a kind of mobile ad hoc networks made of, e.g., (possibly, unmanned) vehicles and humans where, despite a lack of continuous connectivity, data must be transmitted while the network conditions change due to the nodes’ mobility. In these contexts, routing is NP-hard and is usually solved by heuristic “store and forward” replication-based approaches, where multiple copies of the same message are moved and stored across nodes in the hope that at least one will reach its destination. Still, the existing routing protocols produce relatively low delivery probabilities. Here, we genetically improve two routing protocols widely adopted in DTNs, namely, Epidemic and PRoPHET, in the attempt to optimize their delivery probability. First, we dissect them into their fundamental components, i.e., functionalities such as checking if a node can transfer data, or sending messages to all connections. Then, we apply Genetic Improvement (GI) to manipulate these components as terminal nodes of evolving trees. We apply this methodology, in silico, to six test cases of urban networks made of hundreds of nodes and find that GI produces consistent gains in delivery probability in four cases. We then verify if this improvement entails a worsening of other relevant network metrics, such as latency and buffer time. Finally, we compare the logics of the best evolved protocols with those of the baseline protocols, and we discuss the generalizability of the results across test cases.
Koli Calling International Conference call for papers
Authors: Seppälä Otto , Falkner Nickolas
Published: May 2021

We invite you to submit a paper or poster for the 21st Koli Calling International Conference on Computing Education Research (Koli Calling 2021) for the second virtual Koli, hosted around the world and from Finland, 18-21 November 2021.
Verification column
Authors: Lazić Ranko
Published: May 2021

This quarter's article expertly leads us from foundations to state-of-the-art in multiplayer turn-based infinite-duration games for synthesis of reactive systems. Providing examples throughout and an extensive coverage of related work, I expect it will quickly become a standard reference in the field.
Spatial Integration in Normal Face Processing and Its Breakdown in Congenital Prosopagnosia
Authors: Avidan Galia , Behrmann Marlene
Published: May 2021

Congenital prosopagnosia (CP), a life-long impairment in face processing that occurs in the absence of any apparent brain damage, provides a unique model in which to explore the psychological and neural bases of normal face processing. The goal of this review is to offer a theoretical and conceptual framework that may account for the underlying cognitive and neural deficits in CP. This framework may also provide a novel perspective in which to reconcile some conflicting results that permits the expansion of the research in this field in new directions. The crux of this framework lies in linking the known behavioral and neural underpinnings of face processing and their impairments in CP to a model incorporating grid cell–like activity in the entorhinal cortex. Moreover, it stresses the involvement of active, spatial scanning of the environment with eye movements and implicates their critical role in face encoding and recognition. To begin with, we describe the main behavioral and neural characteristics of CP, and then lay down the building blocks of our proposed model, referring to the existing literature supporting this new framework. We then propose testable predictions and conclude with open questions for future research stemming from this model.
(Invited) Silicon Nanosheets as Candidates for Silicon-Based Optoelectronics
Authors: Ryan Bradley J. , Diroll Benjamin T. , Guo Yuqi , Dolgos Carly J. , Wang Qing Hua , Roling Luke T. , Panthani Matthew G
Published: May 2021

The growth in computational ability over the past decades has positively impacted global development, the economy, healthcare, and science. As on-chip components are approaching the atomic scale, alternative paradigms are needed to address the thermal and electronic issues that impose bottlenecks for computing. One approach to address this is with optoelectronics. However, silicon—the backbone of microelectronics—is a poor choice due to its indirect bandgap, while existing optoelectronic materials are incompatible with CMOS infrastructure. Monolayer silicon nanosheets (SiNSs) are an intriguing material that exhibit photoluminescence, and are compositionally-compatible with the CMOS process. Here, we synthesize and characterize monolayer SiNSs, and show spectroscopic evidence that they exhibit a quasi-direct bandgap, which is corroborated by DFT calculations. We probe their thermal stability, demonstrating their structure and photoluminescence are stable beyond the required operating temperatures for computing applications. These optoelectronic properties, CMOS-compatibility, and stability make SiNSs a viable candidate for silicon-based photonics.
(Invited) Electronic and Optical Properties of Quantum-Confined Nanoparticles
Authors: Buerkle Marius , Lozach Mickaël , McDonald Calum , Mariotti Davide , Svrcek Vladimir
Published: May 2021

In this overview we discuss the electronic and optical properties of quantum-confined nanoparticles. In particular, we want to show what we can learn from first-principles calculations, regarding the influence of size effects and surface functionalization on the electronic properties of nanoparticles and demonstrate how the optical properties of nanoparticles can be tailored. Here, we are focusing on sustainable materials, namely silicon-based nanoparticles with hydroxyl functionalization.
Study on Hydrogen-Based Reactive Ion Etching of Ovonic Threshold Switch (OTS) Materials for Phase Change Memory Devices
Authors: Kim Doo San , Gill You Jung , Jang Yun Jong , Kim Ye Eun , Yeom Geun Young
Published: May 2021

Ovonic threshold switch (OTS) materials are used in selector devices for phase change random access memory (PcRAM) circuits and are generally composed of chalcogenide compounds. In this study, etch characteristics of OTS material composed of Ge-As-Te have been investigated using reactive ion etching (RIE) by hydrogen-based gases such as H2, CH4, NH3, etc. Among the investigated hydrogen-based plasmas, NH3 showed the highest etch rate due to the high vapor pressures of the hydrides, but the formation of nitride compounds and the increased roughness were observed on the OTS surface. In the case of CH4+NH3 (1:1 ratio) plasma, the OTS material could be etched at high OTS etch rates without the formation of nitrogen compounds and without increasing the chemical and physical damage on the OTS surface through the formation of volatile CN-related compounds.
Thermoelectrical Characterization of Piezoelectric Diaphragms: Towards a Better Understanding of Ferroelectrics for Future Memory Applications
Authors: Vinuesa Guillermo , Marín Pelayo , Gonzalez Ossorio Oscar , Sahelices Benjamin , Garcia Hector , Castan Helena , Duenas Salvador
Published: May 2021

This work deals with the thermoelectric characterization of commercial lead zirconate titanate (PZT) based piezoelectric diaphragms. An in-depth analysis of the piezo- and ferroelectric behavior of the samples was carried out by measuring current voltage curves and polarization hysteresis cycles in a wide temperature range. We demonstrate that, as the temperature decreases, higher electric fields are needed to completely polarize the sample. Furthermore, I-V measurements, polarization hysteresis loops and coercive fields allow us to confirm that the samples present different grain sizes. From impedance measurements, resonance frequency values, capacitance and permittivity were determined at temperatures ranging from 100 to 320 K. It is shown that impedance maxima shift towards greater frequency values when decreasing the temperature, which is mainly attributed to the appearance of an internal stress that generates larger stiffness in the ceramic. Finally, an electroacoustic characterization was made by measuring the sound pressure of the diaphragms in the human hearing frequency range.
(Invited) History of Micro-/Nano-Electronics Development; Breakthroughs and Innovations
Authors: Iwai Hiroshi
Published: May 2021

The first 1k bit DRAM and microprocessor were mass-produced at the beginning of 1970s. At that time, the technology was 10 ~ 8 µm PMOS LSls, and more than 1,000 MOSFETs were integrated in a chip. This was the beginning of ‘microelectronics.’ Now, they have evolved to 10 nm-range CMOS LSls, and we call it ‘nano-electronics.’ In the past 50 years, we have experienced 23 generations (each about 2.5 years) of the shrinkage, and the MOSFETs size has decreased by 1,000 times, resulting in an increase in integration density with 10 million times. The continuous increase in the integration with the constant rate is the Moore's law, but no one including me could not imagine its continuation of over 50 years. The downsizing of MOSFETs has been accomplished based on the scaling scheme proposed by R. Dennard, but we have encountered very serious problems at every new generation. Fortunately, however, we have so far succeeded in finding the solutions. This paper describes the history of the development of Si MOS Integrated Circuits technology in the past 50 years based on my experience and results which had been obtained by the teamwork of my R & D groups at Toshiba and the collaboration with my colleagues.
(Invited) Characterization of Annealing and Dopant Activation Processes Using Differential Hall Effect Metrology (DHEM)
Authors: Joshi Abhijeet , Rengo Gianluca , Porret Clement , Lin Kun-Lin , Chang Chia-He , Basol Bulent M
Published: May 2021

Differential Hall Effect Metrology (DHEM) technique was used to study dopant activation in n-Si and p-SiGe materials. n-type Si samples were prepared by P ion implantation followed by RTA at temperatures ranging from 750ºC to 950ºC. Junction depth and dopant activation through the layers were correlated with process parameters. Using DHEM mobility profiles, a correlation was also established between the EOR defect location and their elimination through high temperature annealing. DHEM resistivity depth profile displayed increased resistivity in the surface region of B-doped SiGe (50%) epi layer. This electrical behavior is in excellent agreement with expected reduction in B incorporation as strain-relaxation occurs towards the free surface. These results demonstrate prime importance of DHEM capabilities for engineering of advanced contacts.
Effect of Inductively Coupled Electromagnetic Field on Bottom Oxide Etch in a High Aspect Ratio Trench
Authors: Sardo Stefano , Palombizio Antonio , Mannarino Manuel , Redolfi Augusto , Haspeslagh Luc
Published: May 2021

CMOS optical sensors devices are becoming increasingly important and popular for many different applications. Some of these devices are fabricated starting from SOI (Silicon On Insulator) wafers and using semiconductor manufacturing techniques. A common feature of the CMOS sensors is the isolating trench that protects the device from electrical noise. We report on the multistep etch process development to fabricate trenches deeper than usual, in order to isolate the sensor also from stray light interference. We focus the attention on unexpected features that originated during the Buried Oxide (BOX) etch.
Epitaxial Growth of Highly Sb-Doped Ge on p-Ge (100) for Vertical Transistor Applications
Authors: Saputro Rahmat Hadi , Matsumura Ryo , Fukata Naoki
Published: May 2021

To realize nanostructured vertical Ge transistors, we investigated the formation of Sb-doped Ge layers on p-type Ge (100) substrate by molecular beam epitaxy. The effect of dopant source temperature variations during deposition on the crystallinity and electrical properties of epitaxial Ge layers was discussed in detail. The doping at Tdop.: 325-400ºC realizes n-type Ge layers, that indicated by the rectification behavior of the Ge n+/p junction diodes. Moreover, higher Tdop. (~400ºC) resulted in current on-off ratio improvement while maintaining the crystallinity at high dopant concentration.
(Invited) Development of Blue Vertical Cavity Surface Emitting Lasers (VCSELs) with Nanoporous GaN
Authors: Han Jung , Elafandy Rami , Kang Jin-ho
Published: May 2021

Blue and green vertical cavity surface emitting lasers (VCSELs) are expected to be used in future generation display and lighting applications. Applications in virtual reality (VR), augmented reality (AR), retinal scanning display (RSD), and portable projection devices are only a few of the anticipated applications. However, in spite of vigorous pursuit for more than two decades, GaN VCSELs have yet reached commercialization. The main challenge in the technology of III-nitride VCSELs is the fabrication of distributed Bragg reflectors (DBRs) that can provide near-unity reflection and thus support the formation of high-quality vertical cavity. Several groups reported VCSEL operations using epitaxial DBRs (using AlGaN/GaN or AlInN/GaN) and dielectric DBRs (involving lift-offs or epitaxial lateral overgrowth). In this manuscript, I will discuss an alternative approach to this challenging problem by using electrochemistry to create nanoporous GaN as a low-index medium, toward a manufacturable DBR mirror technology to support blue and green VCSELs. This nano-engineering based on electrochemistry can help to circumvent impasses and creates new dimensions in the exploration of optoelectronic devices using GaN.
Impact of Threading Dislocations in GaN Power Switching Devices
Authors: Setera Brett , Christou Aristos
Published: May 2021

Thick epitaxial (3-15 microns) GaN power switching devices are known to contain a high density of crystal defects, and especially threading dislocations in the epitaxial layer. The impact of these defects on device performance and reliability is a topic of ongoing research. This paper presents state-of-the-art methods for analyzing threading dislocation density, growth, and quantification of their impact on leakage current, blocking voltage, and peak E field. The effects of substrate type, epitaxial thickness, and processing techniques on dislocation density have been investigated to provide a roadmap for design and performance optimization of switching two terminal devices. Experimental and simulated data are used in conjunction to model dislocation impact on electrical performance characteristics and to identify techniques to minimize defect density.
Effect of HfO2 Passivation Layer on Light Extraction Efficiency of AlInN Nanowire Ultraviolet Light-Emitting Diodes
Authors: Patel Moulik , Jain Barsha , Velpula Ravi Teja , Nguyen Hieu Pham Trung
Published: May 2021

One of the probable reasons behind the limitation of light extraction efficiency (LEE) in III-nitride nanowire (NW) deep ultraviolet (UV) light-emitting diodes (LEDs) is the presence of the high surface density states that significantly contribute to the non-radiative recombination near the surface. Herein, we investigate the LEE of a single AlInN NW UV LED in the entire UV wavelength regime using finite-difference time-domain simulations. It is found that these LEDs favor transverse-magnetic (TM) polarized LEE over transverse-electric (TE) polarized emission. Further, we examine the role of the HfO2 surface passivation layer in the improvement of LEE of AlInN NW LED at ~282 nm wavelength. Our results show that the TM-polarized LEE of such LED without any passivation is only ~25.2%, whereas the maximum recorded LEE is ~40.6% with the utilization of 40 nm HfO2 passivation layer. This study provides a promising approach for enhancing the LEE of NW UV LEDs.
(Invited) Optically-Active Zero-Dimensional Graphene Quantum Dots with MoS2 for Photodetection
Authors: Kaul Anupama B
Published: May 2021

With its superior electronic properties, large surface area, high mechanical strength-to-weight ratio, exceptional charge carrier mobility reaching the ballistic limit in certain cases, graphene is a material of immense technological importance. However, compared to other two-dimensional (2D) van der Waals solids, such as transition metal dichalcogenides (TMDCs) and black phosphorus, an atomic membrane of graphene absorbs less than about 2% of the incoming light due to its low light absorption cross-section, and lack of a bandgap. However, when sheets of graphene are physically confined into nanoscale dimensions, either as graphene nanoribbons or zero-dimensional (0D) structures, such as graphene quantum dots (GQDs), a band gap in such structures is induced due to quantum confinement. Additionally, semiconducting 2D materials such as MoS2, exhibit a distinct and well-defined band gap ranging from 1.3 eV to 1.8 eV, from bulk to monolayers. In this work, the hybrid structure of 0D graphene quantum dots (GQDs) and semiconducting 2D MoS2 has been investigated that exhibit outstanding properties for optoelectronic devices surpassing the limitations of bare MoS2 photodetectors.
Formation and Characterization of Ge1–x–ySixSny/Ge Heterojunction Structures for Photovoltaic Cell Application
Authors: Nakatsuka Osamu , Asaba Shunsuke , Kurosawa Masashi , Sakashita Mitsuo , Taoka Noriyuki , Zaima Shigeaki
Published: May 2021

We have examined the epitaxial growth of Ge1−x−y
Si
x
Sn
y
ternary-alloy layer on Ge(001) substrates for photovoltaic application. We have investigated the electronic and optoelectronic properties of Ge1−x−y
Si
x
Sn
y
/n-Ge heterojunction structure. A pseudomorphic Ge1−x−y
Si
x
Sn
y
layer with good crystallinity and a high Sn content of 12% can be prepared on Ge substrate with a low temperature growth at 200ºC. We have also demonstrated engineering the absorption energy and the photovoltaic characteristics of undoped Ge1−x−y
Si
x
Sn
y
/n-Ge heterojunction photovoltaic cell. We have examined the epitaxial growth of Ge1−x−y
Si
x
Sn
y
ternary-alloy layer on Ge(001) substrates for photovoltaic application. We have investigated the electronic and optoelectronic properties of Ge1−x−y
Si
x
Sn
y
/n-Ge heterojunction structure. A pseudomorphic Ge1−x−y
Si
x
Sn
y
layer with good crystallinity and a high Sn content of 12% can be prepared on Ge substrate with a low temperature growth at 200ºC. We have also demonstrated engineering the absorption energy and the photovoltaic characteristics of undoped Ge1−x−y
Si
x
Sn
y
/n-Ge heterojunction photovoltaic cell.
(Invited) Layer Transfer Technology for Stacked Multi-Channel Semiconductor-on-Insulator Platform
Authors: Chang Wen Hsin , Hong T.-Z. , Sung P.-J. , Irisawa Toshifumi , Ishii Hiroyuki , Lee Y.-J. , Maeda Tatsuro
Published: May 2021

Continuous scaling of device dimension pushed CMOS technology based on Si materials to its physical limit, alternative high mobility channels such as (Si)Ge and III-V materials have been considered to replace Si to further enhance CMOS performance. In the meantime, ultrathin body (UTB) semiconductor-on-insulator is attractive for fabricating nanowire/nanosheet channel structures for improved gate controllability and immunity against short channel effects in the ultra-scaled high performance and low power dissipation CMOS. To realize multiple channels stacked semiconductor-on-insulator platform on current mainstream Si wafers, layer transfer technology utilizing direct bonding and selective etching was developed to integrate UTB (Si)Ge or InGaAs channels on Si. The devices fabricated with multiple stacked nanowire/nanosheet channels have also been demonstrated through sequential or monolithic 3D integration approach, showing great potential of layer transfer technology for ultimate CMOS structures.
(Invited) Impact of the Substrate Specifications on the Extended Defects Induced by the Deep Trench Isolation
Authors: Mica Isabella , Monge Roffarello Pierpaolo , Dutartre Didier , Basso Michele , Abbadie Alexandra , Frascaroli Jacopo , Tonini Marta , Livellara Luisito , Mari Guido Maria , Bertaiola Simone , Illuzzi Francesca
Published: May 2021

Deep Trench Isolation (DTI) integrated in BCD Technology can induce crystal defectivity. Architectural and process solutions are not enough to completely eradicate the problem in the devices where the DTI reaches the bulk silicon of the epitaxial wafers. The paper highlights the role of BMD depletion around the bottom of DTI for reducing the dislocations. By acting on the content of interstitial oxygen (OI), it is possible to modulate the BMDs generation, for a fixed process flow. Actually, as the OI decreases, the oxygen denuding is promoted. Finally, it is shown that also the B doping of the bulk silicon affects on the crystal defects morphology. Therefore, the substrate specification of OI and resistivity affect the crystal defectivity induced by the DTIs with the BMDs.
(Invited) Applications of the Hakoniwa Method to Impurity Atoms Wandering Inside Si Wafers
Authors: Kamiyama Eiji , Sueoka Koji
Published: May 2021

In this presentation, we review applications for Si-related materials by utilizing the Hakoniwa method, an approach that predicts material properties on the basis of statistical thermodynamics and ab initio calculations. This method describes the behavior of Cu/Fe atoms in B-doped Si crystals. The target material (inside Si wafers) is not uniform and therefore needed to be described in a local circumstance around wandering impurity atoms inside the wafers in order to estimate compatible values with the experiments. Further descriptions are also discussed to estimate Cu/O solubility. These all approaches are spatial-averaged from the viewpoint of statistical thermodynamic treatments. Expanding the Hakoniwa method to a time-averaged approach for the SiO2/Si interface can provide a novel description of oxidizing reactions in the SiO2/Si interface and enable estimation of the interface state density.
Improved Ionic Conductivity of MgM4P6O24 (M = Hf, Zr) Ceramic Solid-State Electrolytes by Sol-Gel Synthesis
Authors: Adamu Mohammed , Kale Girish M
Published: May 2021

Data from electrochemical impedance measurement of MgHf4P6O24 and MgZr4P6O24 solid-state electrolytes show significant improvement in the ionic conductivity of the ceramic electrolytes. The electrical behaviour of MgHf4P6O24 and MgZr4P6O24 solid-state electrolytes were measured using two-probe analysis at a temperature range of 182-764°C, and at a frequency range within 100 mHz to 32 MHz. In this analysis, promising bulk ionic conductivity of 4.52 x 10-4 Scm-1 and 7.23 x 10-3 Scm-1 were achieved for MgHf4P6O24 and MgZr4P6O24 electrolytes, respectively, at impedance maximum temperatures of 747°C and 725°C, respectively. The sol-gel method was deployed in the synthesis of MgHf4P6O24 and MgZr4P6O24 nanoparticles. The thermogravimetric analysis-differential scanning calorimetry analysis (TGA-DSC), and X-ray diffraction (XRD) characterisation techniques were deployed in this study to determine and evaluate the phase composition structure of the nanoparticles calcined at 900°C and the sample pellets sintered at 1300°C.
Corrosion Behavior of Aluminum in Dilute Fluoride and Sulfate Solutions for Use as Bipolar Plate of PEFC
Authors: Alam Md. Ashraful , Jahan Aklima , Suzuki Eiichi , Yashiro Hitoshi
Published: May 2021

The corrosion behavior of pure aluminum was evaluated in dilute concentrations of sodium fluoride and sodium sulfate solutions at 40°C. The open circuit potential (OCP), corrosion amount, and surface roughness were measured to check the corrosion potential, amount of corrosion, and surface roughness, respectively. Scanning electron microscopy (SEM) images and energy dispersive X-ray (EDX) spectra were also taken to observe the surface morphology, elemental composition, and other analyses.
Garnet Nb-Doped Li7La3Zr2O12 Ceramic Electrolyte and Its Composite Electrolyte for Solid-State Lithium Batteries
Authors: Lu Wanzheng , Xue Mingzhe , Zhang Cunman
Published: May 2021

Garnet Li7La3Zr2O12 (LLZO) is a promising candidate of solid-state electrolytes for advanced solid-state lithium batteries (SSLBs). In this work, the Nb-doped LLZO (Li6.5La3Zr1.5Nb0.5O12, Nb-LLZO) ceramic electrolyte is synthesized, and its mechanical properties are explored. An extremely small bending force can break Nb-LLZO ceramic sheets. Moreover, the improved composite membrane composed of as-prepared Nb-LLZO particles, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix is prepared through a modified tape-casting method. Nb-LLZO/PVDF-HFP/LiTFSI composite electrolyte membranes show excellent uniformity and high flexibility. The assembled Li|Nb-LLZO/PVDF-HFP/LiTFSI|LiFePO4 cell exhibits good battery performance. Notably, the cell delivers a high reversible discharge capacity (over 145 mAh g-1) in the first 20 cycles and the Coulombic efficiencies of the major cycling process approach 100% during 35 cycles. This work demonstrates that the Nb-LLZO/PVDF-HFP/LiTFSI composite electrolyte membranes are competent to be applied in SSLBs.
Modeling Water and Thermal Transients Inside Proton Exchange Membrane for Vehicle Application Fuel Cells
Authors: Wang Qianqian , Li Bing , Tang Fumin , Zheng Jim P. , Ming Pingwen
Published: May 2021

Proton exchange membrane fuel cell (PEMFC) is a potential candidate as the power source for vehicle application. However, problems related to water and thermal management must be resolved before their large-scale promotion. Numerical models are often used as powerful tools to describe the electrochemical and transport phenomena occurring in PEMFC, which are important to water and thermal management. In this study, two-phase, non-isothermal, transient models are employed to research the local dynamic characteristics inside PEMFC under road driving conditions and different operating conditions. The simulation results indicate that overload running often causes local high temperature, which can lead to membrane dehydration, voltage loss, and power overshoot as load increases. If the temperature is above the glass transition temperature of the membrane, it will even lead to membrane mechanical degradation. According to our research, controlling the operating temperature below 378 K and reducing the coolant temperature in advance are the effective ways to prevent the aforementioned attenuation.