bluuebunny/crossref_metadata_2025 huggingface dataset:
Nature of Bonds in the Formation of Water Stability of Soil Aggregates
Authors: Fedotov G. N. , Shoba S. A. , Ushkova D. A. , Gorepekin I. V. , Shvarov A. P.
Published: September 2023

The opinion exists that water stability is provided by hydrophobic bonds between organic soil particles; however, there are works in which the main role in the occurrence of this property is assigned to the presence of hydrophilic organic substances in soils. The goal of this study is to clarify the nature of the bonds (hydrophilic or hydrophobic) that ensure the water stability of soils. We used samples of sod-podzolic and gray forest soils, as well as leached chernozem. Experiments to assess water stability were carried out using the method of “blades.” It is based on the dissection of linearly arranged aggregates, which were preliminarily moistened in vacuum to values close to saturation. The energy of hydrophobic bonds depends on the temperature; therefore, the influence of temperature on the value of the determined water stability was studied. Experiments showed that, as the temperature increases, the water stability of aggregates stored in the wet state increases from the moment of selection and decreases as the temperature increases. This indicates the leading role of hydrophobic bonds in the formation of water stability. As for the samples dried to an air-dry state, moistened again, and kept wet for more than two weeks, no temperature dependence of the water stability has been found. Taking into account that the strength of hydrophobic bonds increases with increasing temperature, while that of hydrophilic bonds decreases, the obtained data immutability of water stability can be explained if we assume the joint participation both hydrophobic and hydrophilic bonds in water stability of soil samples that have passed through the stage of drying to an air-dry state. In fact, these results indicate a strong change in the structural organization of soils during drying.
Abdominal ectopic pregnancy
Authors: Dunphy Louise , Boyle Stephanie , Cassim Nadia , Swaminathan Ajay
Published: September 2023

An ectopic pregnancy (EP) accounts for 1–2% of all pregnancies, of which 90% implant in the fallopian tube. An abdominal ectopic pregnancy (AEP) is defined as an ectopic pregnancy occurring when the gestational sac is implanted in the peritoneal cavity outside the uterine cavity or the fallopian tube. Implantation sites may include the omentum, peritoneum of the pelvic and abdominal cavity, the uterine surface and abdominal organs such as the spleen, intestine, liver and blood vessels. Primary abdominal pregnancy results from fertilisation of the ovum in the abdominal cavity and secondary occurs from an aborted or ruptured tubal pregnancy. It represents a very rare form of an EP, occurring in <1% of cases. At early gestations, it can be challenging to render the diagnosis, and it can be misdiagnosed as a tubal ectopic pregnancy. An AEP diagnosed >20 weeks’ gestation, caused by the implantation of an abnormal placenta, is an important cause of maternal–fetal mortality due to the high risk of a major obstetric haemorrhage and coagulopathy following partial or total placental separation. Management options include surgical therapy (laparoscopy±laparotomy), medical therapy with intramuscular or intralesional methotrexate and/or intracardiac potassium chloride or a combination of medical and surgical management. The authors present the case of a multiparous woman in her early 30s presenting with heavy vaginal bleeding and abdominal pain at 8 weeks’ gestation. Her beta-human chorionic gonadotropin (bHCG) was 5760 IU/L (range: 0–5), consistent with a viable pregnancy. Her transvaginal ultrasound scan suggested an ectopic pregnancy. Laparoscopy confirmed an AEP involving the pelvic lateral sidewall. Her postoperative 48-hour bHCG was 374 IU/L. Due to the rarity of this presentation, a high index of clinical suspicion correlated with the woman’s symptoms; bHCG and ultrasound scan is required to establish the diagnosis to prevent morbidity and mortality.
Bilateral, sequential orbital inflammation secondary to relapsing polychondritis
Authors: Al-Janabi Ahmed , Wang Aijing , Gallagher Kevin
Published: September 2023

This report describes a case of a Caucasian man in his 60s with bilateral sequential orbital inflammatory disease associated with relapsing polychondritis (RPC).

He first presented with a subclavian vein periphlebitis/thrombosis and swollen left knee. Two weeks later, he developed right orbital inflammation with restricted eye movements. He was treated initially for possible orbital cellulitis. His inflammation failed to respond to antibiotics but rapidly resolved with oral prednisolone. One year later, he presented with left auricular inflammation, a maculopapular rash on his arms and torso and left orbital inflammation. Again, he failed to respond to antibiotics but had rapid resolution of his inflammatory signs following oral prednisolone.

Based on his previous inflammatory arthropathy, auricular inflammation, orbital inflammation and response to oral steroids, he was diagnosed with RPC based on the McAdam diagnostic criteria. His steroids were tapered and he was commenced on methotrexate as maintenance therapy.
External auditory canal sebaceous carcinoma
Authors: Assiri Sara A , Altwairqi Rahaf Ghazi , Alotaibi Raneem , Ibrahim Mohammed
Published: September 2023

The incidence of sebaceous carcinoma (SC) in the outer one-third of the external auditory canal is considered extremely rare, and only eight case reports have been published. We present a case of a male patient in his late 70s known case of hypertension on indapamide. His medical history included a postspinal tumour that had been treated with surgery and radiation more than 40 years ago and current complaints of right ear pain and purulent discharge. A right ear soft granular tissue mass was found. Complete debulking of the right ear mass was done in conjunction with middle ear exploration, moderately differentiated SC diagnosis was made based on the histopathological analysis. The patient was free of recurrence but then died of an unrelated pulmonary infection. SC should be suspected in elderly patients who present with long-term complaints of a mass with or without otalgia, and these patients should be examined for the presence of such tumours especially if they report a history of radiation. Additionally, more research is warranted to investigate the association of diuretics with SC.
Simulation of fluid dynamics and turbulence during phacoemulsification using the new propeller turbo tip
Authors: Wang Xiaoliang , Wang Xiaogang
Published: September 2023

Purpose

To investigate the fluid dynamics and turbulence in the anterior chamber during phacoemulsification with a new propeller turbo tip using computational fluid dynamics methods.

Methods

A theoretical study, three-dimensional model with the corresponding mathematical equations for the propeller turbo phaco tip, anterior chamber and lens capsular bag was developed. A simulation was performed for the new propeller turbo tip with various parameter settings (vacuum, irrigation bottle height and phaco power). Fluid dynamics and turbulence in the anterior chamber, lens capsular bag and phaco tip were evaluated. The linear relationship between the different setting parameters and a stable anterior chamber pressure was assessed.

Results

The fluid dynamic turbulence was mainly symmetrically distributed in the anterior chamber. Propeller turbo phaco tip vibration caused increased fluid velocity and asymmetrical fluid turbulence in the metal lumen but had little influence on dynamic intraocular pressure. Reasonable phaco machine parameter settings can maintain a stable intraocular pressure during phacoemulsification.

Conclusions

Evaluation of phacoemulsification fluid dynamics using computational simulation methods could provide detailed information about the influence of the propeller on dynamic intraocular pressure during phacoemulsification, which is useful for a better understanding of this procedure.
Extensive gender disparity in top medical schools and their affiliated dermatology departments: a cross-sectional study
Authors: Ding Jeffrey , Tao Brendan Ka-Lok , Joseph Marissa , Chawla Sahil , Amin Wali , Khosa Faisal
Published: September 2023

Background

Previous studies demonstrate female under-representation in top medical school leadership and dermatology departments, although separately. Here, we investigate the extent and interplay of gender disparity between these two bodies.

Objective

To compare the extent of gender disparity among top 15 US medical schools with affiliated dermatology programmes.

Methods

Cross-sectional study conducted in 2022. Faculty gender, academic rank, leadership position and membership of medical school leadership or affiliated dermatology department were extracted from public institutional sources. Research metrics (h-index, citations, publication span and publication counts) were collated using Elsevier’s SCOPUS tool.

Results

From 1243 individuals (31.7% women), 840 held medical school leadership positions and 403 were affiliated dermatology faculty. Rank biserial correlation indicated a significant relationship of male gender with higher academic rank (r=−0.305, p<0.001), leadership position (r=0.095, p=0.004) and scholarly metrics. More medical leadership individuals had higher academic rank than dermatology faculty; we, therefore, hypothesise a pipelining of rising departmental faculty into leadership positions.

Limitations

Public faculty listings seldomly reported leadership appointment age and length, career duration and mid-career breaks.

Conclusion

Continued diversity efforts are recommended to improve female under-representation in medical school leadership and affiliated dermatology faculties.
Gender equity in an NHS theatre environment: an example of compassionate leadership and a discussion of psychological safety, inclusivity and civility
Authors: Kaur Anjana
Published: September 2023

Introduction

Effective clinical leadership can seem at a loss in the current National Health Service (NHS). The following reflection describes how a peer support network for menopausal symptoms and introduction of free sanitary products in female changing rooms proved greatly beneficial to promoting genuine equity in a Welsh NHS theatre environment. The latter aimed to help female staff working in time pressured and high stress environments on days when they are caught out by their menstrual cycle.

Method

The Driscoll reflective model has been chosen to critically appraise these behaviours, providing an opportunity to focus on the details of the event, analyse the impact of behaviours and evaluate best future practice.

Conclusion

This is a pragmatic, tangible and cost-effective approach to creating gender equity in a busy NHS environment.
Improving the Effectiveness of Eigentrust in Computing the Reputation of Social Agents in Presence of Collusion
Authors: Cotronei Mariantonia , Giuffrè Sofia , Marcianò Attilio , Rosaci Domenico , Sarnè Giuseppe M. L.
Published: September 2023

The introduction of trust-based approaches in social scenarios modeled as multi-agent systems (MAS) has been recognized as a valid solution to improve the effectiveness of these communities. In fact, they make interactions taking place in social scenarios much fruitful as possible, limiting or even avoiding malicious or fraudulent behaviors, including collusion. This is also the case of multi-layered neural networks (NN), which can face limited, incomplete, misleading, controversial or noisy datasets, produced by untrustworthy agents. Many strategies to deal with malicious agents in social networks have been proposed in the literature. One of the most effective is represented by Eigentrust, often adopted as a benchmark. It can be seen as a variation of PageRank, an algorithm for determining result rankings used by search engines like Google. Moreover, Eigentrust can also be viewed as a linear neural network whose architecture is represented by the graph of Web pages. A major drawback of Eigentrust is that it uses some additional information about agents that can be a priori considered particularly trustworthy, rewarding them in terms of reputation, while the non pre-trusted agents are penalized. In this paper, we propose a different strategy to detect malicious agents which does not modify the real reputation values of the honest ones. We introduce a measure of effectiveness when computing reputation in presence of malicious agents. Moreover, we define a metric of error useful to quantitatively determine how much an algorithm for the identification of malicious agents modifies the reputation scores of the honest ones. We have performed an experimental campaign of mathematical simulations on a dynamic multi-agent environment. The obtained results show that our method is more effective than Eigentrust in determining reputation values, presenting an error which is about a thousand times lower than the error produced by Eigentrust on medium-sized social networks.
A closeness centrality reconnection strategy to suppress the traffic-driven epidemic spreading
Authors: Ma Jinlong , Wang Siyu
Published: September 2023

The inappropriate network structure often facilitates the epidemic spreading driven by traffic. In this paper, an edge reconnection strategy based on node closeness centrality is proposed to decrease the speed of epidemic spreading. In simulations, some evaluation indicators are introduced to measure the optimized effect. After adopting the proposed strategy, the spectral radius of optimized network gradually decreases as the number of edge reconnection increases, and eventually reaches a stable value. Consequently, the epidemic threshold, as a significant indicator to evaluate the speed of epidemic spreading, shows a noticeable increase. In addition, the comparisons of average path length and the scale of epidemic spreading can be intuitively obtained.
Mass-spectra of light-heavy tetraquarks
Authors: Tiwari Rohit , Oudichhya Juhi , Rai Ajay Kumar
Published: September 2023

The mass spectra of light-heavy tetraquarks [Formula: see text] ([Formula: see text]) are computed in a nonrelativistic diquark model with one-gluon exchange plus confining potential. In the diquark model, a [Formula: see text] state is regarded to be made of a light-heavy diquark ([Formula: see text]) and an antidiquark [Formula: see text] in antitriplet and triplet color configuration, respectively. The masses of charm mesons were calculated in order to fit the model parameters used to create the masses of tetraquarks and therefore enhance the model’s reliability. The masses of [Formula: see text] tetra-quark states are determined to be in the range of 3.8–4.7[Formula: see text]GeV, which is consistent with the experimentally reported charmonium-like states. In particular, the [Formula: see text], [Formula: see text] and [Formula: see text] tetraquarks, which have been seen experimentally, may all be described by our model.
Effects of deformation on Zn atom-adsorbed borophene
Authors: Su Qing , Wang Ying , Gao Xuewen , Liu Guili , Zhang Guoying
Published: September 2023

The effects of tensile and compressive deformation on the structural stability, electronic structure and optical properties of the Zn atom-adsorbed borophene system, which are exhibited by reflectivity, absorption coefficient, bandgap and adsorption energy, were studied using the first-principles calculations based on density functional theory (DFT). The borophene planes were found to be distorted following Zn atom adsorption. The adsorption energy calculations show that the stability decreases both under tensile and compressive strains. When tensile and compressive loading increase to 5%, respectively, the system loses the stability and the ability of adsorbing Zn atoms on borophene. The band structure and density of states analysis show that the band structure of borophene is changed by the Zn atom adsorption, with a band overlap near the Fermi level and more impurity energy levels in the conduction band. The hybridization is formed between Zn atom and borophene in the range of –12[Formula: see text]eV to 6[Formula: see text]eV, with the s and p orbitals both contributing to the conduction and valence bands, but p orbitals make a larger contribution to the total density of states than s orbitals. Studies of optical properties have shown that tensile and compressive strains both increase the dielectric constant of the adsorbed system, with compressive strains causing a redshift in the major peaks of the real and imaginary parts of the spectrum. The tensile strain has little effect on the absorption coefficient and reflectance of the borophene. As the compressive strain increases, the peak absorption coefficient of the adsorbed system is shifted to the blue and the peak reflectance is redshifted.
SharpenNet: Detecting Anti-Forensics USM Sharpening Adversarial Examples Based on ConvNeXt
Authors: Yu Haozheng , Fan Bing , Xu Bing , Zhu Xiaogang
Published: September 2023

Image sharpening detection, as a crucial branch of image forensics research, has attained a satisfactory level of performance with the assistance of deep learning. However, due to the nature of convolutional neural network (CNN) models, adversarial examples synthesized by generative adversarial networks (GANs) can easily attack existing forensics models. Therefore, deep learning-based forensics faces new challenges. In this paper, a novel architecture inspired by ConvNext is proposed to detect synthesized adversarial USM sharpening images. Through practical demonstration, our proposed technique achieves satisfying performance in recognizing adversarial samples that outperform previous sharpened image forensic systems. In addition, we have undertaken an ablation analysis of our suggested network topology and analyzed the efficacy of different enhancements.
Imperfect Debugging-Based Generalized Exponential Testing Effort Estimation for Software Fault Detection and Removal
Authors: tiwari Asheesh , Sharma Ashish
Published: September 2023

In the current technological era, the reliability growth model depicts the failure in software that is employed for estimating the reliability of software. Conventional software reliability growth model (SRGMs) usually presume that faults in software are immediately corrected once a software fault is found and no new faults are introduced. This consideration can be impractical. However, introduction of several new faults is possible throughout debugging, which is called imperfect debugging. During such a process of debugging and introduction of new faults, consumption of testing effort also plays an important role. Hence, in this paper, two models are proposed that incorporate testing effort along with imperfect debugging during fault correction. Additionally, the combined testing effort is the addition of two efforts, specifically detection effort as well as correction effort. The formulated models are validated for real data set and contrasted with additional famous SRGMs. These inferences indicate that Model 2 performs best in terms of fitting and prediction capability.
Analyzing Spillover Effects Among BRICS Stock Markets: Application of Copula and DCC-MGARCH Model
Authors: Tripathy Naliniprava , Panda Pradiptarathi
Published: September 2023

This study examines the nonlinear dependence and tail dependence of BRICS countries’ stock markets and the contagion effect among Brazil, Russia, India, China, and South Africa (BRICS) countries’ daily stock markets using the COPULA model from January 2000 to February 2019. The study employs the DCC-MGARCH model and Diebold and Yilmaz volatility spillover model to assess the interdependence dynamics across BRICS countries’ stock markets. The copula results suggest that the BRICS country’s stock markets are independent of each other. The conditional correlation between BRICS is negative and statistically significant, suggesting that the negative relationship among BRICS is an important signal for international investors to diversify among these countries and get the economic value of their investment. Further, Brazil, China, and South Africa are the net volatility transmitter, at the same time India and Russia are the net volatility receiver during the study period. The study proposes that policymaker of BRICS needs to interchange views and mutually map policies to appeal to global investment more.
Short- and Long-Run Effects of Forex Volatility on International Trade– A Case of Middle Eastern Country
Authors: Abdulkarim Rasha , Mohnot Rajesh , Dahan Abdulkarim
Published: September 2023

This research was aimed at understanding the effects of exchange rate volatility on UAE’s international trade. To examine the effects, 10 of the top trading partners of UAE were considered for this study. Additionally, in order to determine the volatilities of UAE’s top 10 trading partners’ currencies, the GARCH (1,1) model was used. After that the Autoregressive Distributed Lag (ARDL) bound testing approach determined the long-run relationship between the volatilities of the currencies and the trade of UAE. Furthermore, the short-run relation between volatility and trade was detected using the Granger causality test. The results indicated that in the long run the volatility of the Chinese Renminbi, the Euro and the Saudi Riyal affect UAE’s exports, while UAE’s imports in the long run are affected by the volatility of the Iranian Rial and the Euro as well. On the other hand, the volatilities of the Indian Rupee and the Omani Riyal tend to affect UAE’s exports in the short term, however, the imports of UAE in the short run are actually affected by the volatilities of the Euro and the Swiss Franc.
On the Extremal Values of the Weighted Integrity of a Graph
Authors: Goddard Wayne , VanLandingham Julia
Published: September 2023

The integrity of a graph [Formula: see text] is defined as the minimum value of [Formula: see text] taken over all [Formula: see text], where [Formula: see text] denotes the maximum cardinality of a component of graph [Formula: see text]. In this paper, we investigate bounds on the maximum and minimum values of the weighted version of this parameter. We also consider the same question for the related parameter vertex-neighbor-integrity.
Nonlinear Free Vibration of Anisogrid Lattice Cylindrical Panel Using the 2D Double Exponential Sinc Collocation Method
Authors: Qiu Liuyuchen , Tang Hua
Published: September 2023

This study explores the nonlinear free vibrations of anisogrid lattice cylindrical panels under clamped circumstances for the first time. The lattice panel is made of repeating circumferential hexagonal unit cells with helical and circumferential isotropic ribs. The panel’s stiffness and mass are calculated using a continuous model based on orthotropic deep panel theory. The strain–displacement relationships are based on von-Kármán’s geometrically nonlinear theory. Using the Hamilton principle, nonlinear two-dimensional (2D) motion equations are extracted in their strong form. A 2D collocation approach based on the Sinc functions with double exponential (DE) transformation with a high convergence rate is used to solve the governing motion equations. The time variable is then eliminated from the equations using the weighted residual Galerkin procedure. Finally, the system’s nonlinear natural frequencies are computed using an iterative algorithm based on the bilateral displacement control. The influence of unit cell features, such as the angle of helical ribs, the number and thickness of ribs, and the panel dimensions, is examined in detail on the panel’s linear and nonlinear vibration behavior.
Study on the Effect of Different Sandwich Thicknesses on the Impact Resistance of Laminated Glass
Authors: Zhang Youning , Wei Xiangrui , Wang Qian , He Jingjing , Zhang Yunkuan , Wang Xiang
Published: September 2023

Polyvinyl butyral (PVB) laminated glass is widely used in architectural structures and automotive glass due to its remarkable cushioning and cohesive properties, and its lamination thickness has a significant effect on the overall impact resistance of the glass. In this paper, two conventional laminated glass thicknesses of 0.76 mm and 1.52 mm were selected to study the dynamic performance and damage morphology of laminated glass under three different impact velocities using light gas gun impact tests combined with industrial CT scanning-3D reconstruction techniques. The results showed that the PVB sandwich thickness had a significant positive correlation with the energy absorption effect, but under different impact velocities and glass thickness, the sandwich thickness and impact resistance showed a differentiated “marginal effect”. At moderate impact velocities, the impact resistance was most sensitive to the change in sandwich thickness. With the increase in glass thickness, the sensitivity of impact resistance to the change of sandwich thickness decreased. According to the characterization of full-dimensional cracks under medium-velocity impact conditions, it could be seen that the sandwich had the function of buffering dissipation and gathering recovery in different stress directions, and the thickness of the sandwich was a key functional parameter to reduce the flying of glass fragments. Therefore, the results of this study can provide a reference for the analysis and design of the impact resistance of PVB laminated glass.
Titchmarsh–Weyl theory for impulsive q-Dirac equation
Authors: Allahverdiev Bilender P. , Tuna Hüseyin , Isayev Hamlet A.
Published: September 2023

In this paper, the Titchmarsh–Weyl theory of the impulsive [Formula: see text]-Dirac equation is studied.
Incorporating diverse voices in geoconservation in Portland, Jamaica
Authors: Salgado-Jauregui Estefanía , Ellins Katherine , Martindale Rowan C. , Henry Denise , Gordon-Smith Debbie-Ann
Published: September 2023

Sites of geological relevance in East Portland are representative of the geological history of Jamaica and are important to elucidate Caribbean geotectonic evolution. Geological significance overlaps with natural and cultural heritage of international relevance, especially related to Maroon communities. In this region, the Jamaican highest peak rises steeply from sea level; the ocean is the focus of important conservation efforts. This study employs an interpretative phenomenological analysis to explore place attachment as experienced by East Portland residents. We engaged in conversations with 16 diverse community members through interviews and a focus group. Two dimensions of place attachment emerged: place identity and place dependence, showing that East Portland is home to people who depend on, identify with and are committed to protecting nature. We present an approach to mapping place attachment, which resulted in an important tool of analysis when overlapping with layers of information like geoheritage. The geological significance, natural and cultural richness and the connections the locals have with nature make East Portland an ideal prototype for geoconservation. This study also reveals that attachment to a place does not necessarily correspond to attachment to geoscientific significance; for common meanings to emerge, geoscientists and locals must collaborate.
Relating Optimal Repairs in Ontology Engineering with Contraction Operations in Belief Change
Authors: Baader Franz
Published: September 2023

The question of how a given knowledge base can be modified such that certain unwanted consequences are removed has been investigated in the area of ontology engineering under the name of repair and in the area of belief change under the name of contraction. Whereas in the former area the emphasis was more on designing and implementing concrete repair algorithms, the latter area concentrated on characterizing classes of contraction operations by certain postulates they satisfy. In the classical setting, repairs and contractions are subsets of the knowledge base that no longer have the unwanted consequence. This makes these approaches syntax-dependent and may result in removal of more consequences than necessary. To alleviate this problem, gentle repairs and pseudo-constractions have been introduced in the respective research areas, and their connections have been investigated in recent work. Optimal repairs preserve a maximal amount of consequences, but they may not always exist. We show that, if they exist, then they can be obtained by certain pseudo-contraction operations, and thus they comply with the postulates that these operations satisfy. Conversely, under certain conditions, pseudo-contractions are guaranteed to produce optimal repairs. Recently, contraction operations have also been defined for concepts rather than for whole knowledge bases. We show that there is again a close connection between such operations and optimal repairs of a restricted form of knowledge bases.
Segmented, Negative-Sense RNA Viruses of Humans: Genetic Systems and Experimental Uses of Reporter Strains
Authors: Hamele Cait E. , Spurrier M. Ariel , Leonard Rebecca A. , Heaton Nicholas S.
Published: September 2023

Negative-stranded RNA viruses are a large group of viruses that encode their genomes in RNA across multiple segments in an orientation antisense to messenger RNA. Their members infect broad ranges of hosts, and there are a number of notable human pathogens. Here, we examine the development of reverse genetic systems as applied to these virus families, emphasizing conserved approaches illustrated by some of the prominent members that cause significant human disease. We also describe the utility of their genetic systems in the development of reporter strains of the viruses and some biological insights made possible by their use. To conclude the review, we highlight some possible future uses of reporter viruses that not only will increase our basic understanding of how these viruses replicate and cause disease but also could inform the development of new approaches to therapeutically intervene.
(Invited) In-Depth Understanding of the Key Contributors to the Total Flicker Noise in Advanced Logic Devices
Authors: Cretu Bogdan , Tahiat Abderrahim , Veloso Anabela , Simoen Eddy
Published: September 2023

The aim of this work is to perform an in-depth analysis in order to identify the key contributors to the total flicker noise in advanced MOSFET technologies, e.g. UTBOX, Gate-all-around (GAA) nanowire or nanosheet FET devices. For all investigated devices of these technologies an increase of the flat-band noise power spectral density level with the increase of the applied gate voltage was observed. This may be related to the correlated carrier number and mobility fluctuations noise mechanisms and/or with additional access resistances noise contributions. Different existing models have been applied in order to identify the key 1/f noise mechanism. However, a discrepancy in the obtained 1/f noise contributors is highlighted, and leads to some questioning about which employed model is most accurate and gives good indications on the key contributors and estimated parameters of the total flicker noise.
Impact of Oxygen on the Generation of Slip Lines and the Electronic Properties of Si-based Substrates
Authors: Abbadie Alexandra , Pribat C. , Gredy V. , Brouzet V. , Sereix E.
Published: September 2023

We focus on slip line formation and propagation on different types of Si and SOI substrates that underwent high temperature anneals during 65nm RFSOI device fabrication. Different parameters are found to contribute to slip line formation and dislocations propagation, mainly the substrate properties (thickness, layer and oxygen in silicon handle), the temperature gradients and the support between furnace carriers and backsides of substrates. Several parameters contribute to substrate deformation, e.g. the warpage increase. The warp degradation is found to be directly linked to low oxygen concentrations in silicon handle. This understanding is very helpful to introduce and process new substrates in advanced front-end process flows for MOS device fabrication.
Atomic Structures and Chemical states of active and inactive dopants in GaN
Authors: Yamashita Yoshiyuki , Tang Jingmin , Hashimote Yusuke , Matsushita Tomohiro
Published: September 2023

We investigated atomic structures and chemical states of active and inactive dopant sites for Mg- and Si- doped in GaN using photoelectron holography and X-ray absorption near edge structure. In the case of Mg-doped GaN, we found that a Mg atom substituting a Ga atom (MgGa) is an active dopant site in GaN whereas MgGa with two H atoms is an inactive dopant site in GaN. We found that a Si atom substituting a Ga atom is an active dopant site in Si-doped GaN whereas Si3N4 is an inactive dopant site in GaN.
(Invited) Growth and Characterization of 200 mm SiC Crystals and Substrates
Authors: Carria Egidio , Sörman Erik , Thörnberg Jimmy , Ellison Alexandre , Magnusson Bjorn , Riva Carlo
Published: September 2023

SiC power device technology has over the past years continued to gain massive interest in automotive and industrial applications. Most devices are today fabricated on 150 mm diameter substrates while the 200 mm diameter substrates are still at early stage in both development and in terms of mass production. In this paper, we report the latest progress on STMicroelectronics 200 mm diameter crystals and substrates. To handle the mechanism behind the crystal growth process you need to control the temperature and pressure in the customized graphite growth chamber. We detail the methods that allow to characterize the quality of the ingot by monitoring the relevant properties both related to the grown crystal and to the produced substrate. We also describe the key parameters to be controlled on the substrate to be sure it is suitable for device making (i.e. mechanical behavior, resistivity, surface roughness, effectiveness of the surface preparation).
Inline Bondwave Monitoring for Direct Bonding, Process Optimization and Impact on Post-Bond Distortion
Authors: Michaud Laurent Gaëtan , Fournel Frank , Morales Christophe , Schmidbauer Martin , Abadie Karine , Plach Thomas , Wimplinger Markus
Published: September 2023

Direct wafer bonding is essential in semiconductor manufacturing, with bondwave propagation dynamics influencing the overall bond quality. The main factor impacting bondwave velocity dynamics are substrate rigidity, fluid viscosity and adhesion energy between the two surfaces. The latter, which depends on substrates properties and process parameters, is key and should be controlled and monitored for fusion bonding applications. The use of an inline infrared (IR) monitoring within an automated fusion bonding equipment, EVG®850LT, facilitates real-time defect detection, root cause analysis, and bond re-workability. The equipment, which features a sealed bonding chamber equipped with an IR camera and a reflective chuck, together with a plasma chamber for pre-processing enables the assessment of various process conditions. Post-bond distortions are then evaluated using high-resolution metrology. Bondwave monitoring use-cases, a detailed analysis of bondwave speed impact on bonded stack distortion and the influence of diverse process parameters on bondwave propagation are presented or discussed in the current paper.
(Invited) Hybrid Bonding for 3D Applications: Improvements and Limitations
Authors: Deloffre Emilie , Ayoub Bassel , Lhostis Sandrine , Dettoni Florent , Fournel Frank , Montméat Pierre , Mermoz Sebastien
Published: September 2023

With hybrid bonding pitch reduction, many challenges are arising such as optimized metrology measurement, bonding wave propagation understanding and hybrid surface characterization. By analyzing incoming wafer and how tool setting impacts bonding, overlay values below 110 nm for production wafers can be achieved with 100% electrical yield. Hybrid bonding extends further to IC Logic application or Memory and not only CMOS image sensor. For some of those products, the temperature of usual post bonding thermal annealing (400°C) cannot be applied. Consequently, many studies have been performed on developing low-temperature bonding. To add flexibility to hybrid bonding, new processes such as Surface Activation Bonding (SAB) and Die to Wafer bonding (D2W) have been developed to fit heterogenous integration.
Fabrication and Electrical Characterization of GaAs/GaN Junctions
Authors: Ishimi Shota , Hirose Makoto , Shimizu Yasuo , Ohno Yutaka , Nagai Yasuyoshi , Liang Jianbo , Shigekawa Naoteru
Published: September 2023

We fabricate p+-GaAs/n-GaN and n+-GaAs/n-GaN junctions using surface activate bonding and measure their capacitance-voltage and current-voltage characteristics. We find that the characteristics of the two junctions are close to each other, which suggests that the band profiles of GaN layers in the two types of junctions are almost the same, i.e., the Fermi-level pinning occurs at the GaAs/GaN interfaces. Breakdown occurs at a reverse bias voltage ≈ -60 V in both junctions. The observed breakdown voltage corresponds to an electric field of as high as ~ 1.6 MV/cm, which is comparable to a reported breakdown field of GaN. We also excite minority electrons in the p+-GaAs layer using a 488-nm laser and successfully observe the photocurrent due to the transport of minority electrons across the reverse-biased GaAs/GaN interfaces.
Vacuum Quality Impact on Covalent Bonding
Authors: Abadie Karine , Lomonaco Quentin , Michaud Laurent , Fournel Frank , Morales Christophe
Published: September 2023

Covalent bonding is based on a direct bonding process. The first step of this process consists in creating dangling bonds at the wafers surface. When the two activated surfaces are brought in contact, covalent bonds result between them. Dangling bonds are highly reactive. Any queue time between activation and bonding is crucial, as dangling bonds must be preserved. It can be even more difficult to preserve the dangling bonds in the case of bonding process in temperature. One way, commonly used, is to always stay under Ultra High Vacuum (UHV). However, the UHV environment may affect the bonding process. This paper aims at studying the impact of the UHV quality on the dangling bonds stability and bonding quality.
Preferred Grain Orientation to Enhance Interdiffusion at Room Temperature in Atomic Diffusion Bonding: A Fundamental Study Using Ni and Cu Films
Authors: Uomoto Miyuki , Kikuchi Shun , Goto Fuki , Shimatsu Takehito
Published: September 2023

The interdiffusion and interface structure at the bonded interface of Cu and Ni films obtained using atomic diffusion bonding (ADB) processing was assessed in relation to films structures used for bonding. Improvement of the (111) preferred grain orientation in Ni and Cu films used for bonding enhanced the crystal lattice rearrangement at the bonded interface of Ni–Cu bonded films, leading to large interdiffusion. The representative interdiffusion length evaluated using magnetic characterization was 5.4 nm for a Ni(20 nm)–Cu(10 nm) bonded interface with Ti underlayers. Grain boundary diffusion partially contributed to the interdiffusion length independently of the (111) preferred grain orientation of films. These results indicate that ADB bonding performance enhancement can be achieved with a high degree of (111) preferred grain orientation and low surface roughness in ADB processing using metal films having an fcc crystal structure such as Al, Au, Ag, Cu, Ni, and Pt.
Oxide-Free SiC-SiC Direct Wafer Bonding and Its Characterization
Authors: Kerepesi Péter , Rebhan Bernhard , Danner Matthias , Stadlmann Karin , Groiss Heiko , Oberhumer Peter , Duchoslav Jiri , Hingerl Kurt
Published: September 2023

In this study, the feasibility of oxide-free room temperature wafer bonding process was demonstrated for 4H-SiC wafers with in situ surface oxide removal. The investigations covered three areas: incoming metrology of the original wafer, characterization of activated single wafer and analysis of bonded wafer pairs. The focus was on compositional, chemical, mechanical and morphological analysis of the surfaces and of the bonded interfaces. Incoming wafers were inspected whether they fulfill the requirements of wafer bonding, and activated wafers were characterized to measure the surface modifications. The quality of the bonded wafers and the bonding energy were verified using scanning acoustic microscopy measurements as well as the Maszara blade test. Furthermore, cross-section transmission electron microscopy was used to investigate the amorphous layer at the bonding interface. The work reported is a demonstration of the capability of different characterization methods regarding SiC-SiC wafer bonding.
Blade Test in Atmospheric-Pressure Ar Gas to Characterize Bonded Interface Fabricated Using Atomic Diffusion Bonding
Authors: Iemura Hikaru , Goto Fuki , Uomoto Miyuki , Shimatsu Takehito
Published: September 2023

A blade test was applied in atmospheric-pressure Ar gas for wafers bonded using atomic diffusion bonding processing. We assessed the variation of the values of surface free energy at the bonded interface γ calculated, for convenience, from the debonding length. For interfaces bonded using thin Zr and Ti films, γ measured in Ar maintained the initial value γ0(Ar) in the initial region of observation time t and started decreasing as t increased further. Results indicate that γ0(Ar) corresponds to the value without water stress corrosion effects. The initial value of γ measured in air with a higher blade insertion-speed was almost equal to γ0(Ar). Result obtained for wafers bonded using Al2O3 films were almost identical to those obtained using metal films. However, γ for wafers bonded using ZrO2 films did not maintain their initial values. They decreased gradually as t increased, even in Ar, suggesting high water stress corrosion effects.
Comparison of MEA Degradation through FCV Actual Driving Test and Load-Cycle Durability Test
Authors: Katayama Shota , Matsumoto Masashi , Imai Hideto , Asaoka Takahiko , Amemiya Kazuki
Published: September 2023

The degradation of a membrane electrode assembly (MEA) after an actual driving test was analyzed, and its mechanism was compared with that of a load-cycle durability test in a laboratory. MEA samples were extracted from an FC stack of a Toyota MIRAI 2014th model which had been operated in actual driving of 200,000 km for approximately 6000 h. The degradation distribution across the MEA plane was found to be insignificant. The electrolyte membrane did not show significant degradation affecting its properties following the durability tests. The MEA performance degradation is primarily attributed to the deterioration of the catalyst activity and oxygen transport properties in the catalyst layer, which is mainly caused by catalyst coarsening. The degradation was well simulated by the NEDO load-cycle durability test of 30,000 cycles. The evaluation results are applicable to validation of AST protocols and model-simulation of MEA degradation.
Regeneration Strategies for Ruthenium-Poisoned ORR Catalysts in Reformate PEM Fuel Cells
Authors: Guo Qiang , Hasché Frédéric , Oezaslan Mehtap
Published: September 2023

PEM fuel cells operating on reformate gases suffer from Ru crossover and its re-deposition in the cathode catalyst layer. Therefore, strategies for regeneration of Ru-poisoned ORR catalysts are needed. Here, we developed a regeneration protocol and tested this for commercial PtRu2/Vulcan, which represents a worst case scenario of Ru-poisoned ORR catalysts due to the high Ru content and good intermixture with Pt. Our protocol consists of two chronoamperometric cycles, namely at 1.4 VRHE for 5 minutes followed by 1.6 VRHE for 100 s. The Ru deletion as a function of the number of regeneration cycles was in-situ monitored by electrochemical CO stripping method. The mass and specific ORR activities of the recovered PtRu2/Vulcan increase by 6-times and 4.4-times, respectively. Very remarkably, our regeneration protocol aims to trigger the Ru dissolution by forming the RuO4 during the OER without a negative impact on the catalytic ORR properties of Pt.
Corrosion Behaviour of Ni-Based Alloys 230, 617 and 601 in CO2 Gas at 750 and 850°C
Authors: Li Haoyi , Nguyen Thuan , Zhang Jianqiang , Young David
Published: September 2023

This paper investigated corrosion behaviors of three nickel-based chromia-forming commercial alloys (230, 617 and 601) at 750°C and 850°C in a CO2 environment for up to 500 h. All three alloys showed good oxidation resistance by forming mainly a protective chromia layer with low weight changes. Internal Al2O3 was precipitated beneath a thin protective chromia layer for all cases. For 230 and 617 alloys, NiO and Cr-rich spinel outer layers were formed, but for 601 less iron and nickel outward diffusion was observed at both temperatures. Furthermore, some minor alloy elements (Mn, Ti, and Co) were observed to diffuse into the chromia layers.Wagner’s theory predicted that alloy concentrations were marginal for chromia formation at both temperatures for the test alloys. The observation of protective chromia formation can be attributed to the effect of other alloying elements, e.g. Al, Mn, Ti, Si etc. Wagner’s theory also predicted that this critical chromium concentration decreased with increasing the oxidation temperature, which is consistent with the experimental observation.The Al and Si oxides formed an additional protective barrier between the matrix and the chromia layer, preventing the diffusion of iron and nickel outwards and therefore increasing oxidation resistance. Manganese effectively prevented carburization by combining with chromia to form the outermost spinel oxide layer, increasing oxidation/carburisation resistance. Titanium diffused through the chromia layer, accelerating chromium diffusion and leading to higher kinetic rates. Tungsten reduced oxidation resistance by increasing the metal vacancies and therefore outward diffusion of Ni, Fe and Mn through the chromia scale.
Reactive Condensation of Cr Vapor on Aluminosilicates Containing Alkaline Oxides
Authors: van Leeuwen Travis Kent , Dowdy Ryan , Guerrero Amberly , Gannon Paul
Published: September 2023

This research aims to improve fundamental understanding of the reactive condensation of Chromium (Cr) vapors, which are generated in many high-temperature (>500℃) process environments and can form potentially problematic condensed hexavalent (Cr(VI)) species downstream. . This study focuses on the effects of alkaline oxide additives in aluminosilicate fibers on Cr condensation and speciation. Cr vapors were generated by flowing humid, high-temperature air over chromia (Cr2O3) powder, with aluminosilicate fiber samples positioned downstream. Results indicate presence of hexavalent chromium (Cr(VI)) species condensed on all samples investigated, with significantly more on those containing alkaline oxides (CaO and MgO) additions. Comparative results and analyses are discussed to help inform mechanistic understanding and future related research and engineering efforts.
Effects of Current Collector on Internal Visualization of Solid Oxide Cells
Authors: Yoshiga Ko , Okamoto Takeaki , Tachikawa Yuya , Sasaki Kazunari
Published: September 2023

Visualization of reactions occurring inside a solid oxide cell (SOC) during operation is difficult due to the limitation of the operatable temperature to use various sensors and measurement equipment. Therefore, we are investigating a visualization method to combine three-dimensional simulation with in-operando temperature observation inside SOCs. In this study, we focused on evaluating the effect of a current collector shape on the cell performance and temperature distribution. As a result, we confirmed that the effects of several current collector shape modifications appeared in the temperature distribution. Based on the calculated temperature and current density distributions, we proposed an appropriate current collector shape for observing the temperature distribution inside the cell by experiment. Using the practical observation setup model considered in this study, the influence of sulfur poisoning on the temperature distribution was also calculated and evaluated.