bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) In situ muon spin relaxation for probing ion diffusion in lithium batteries
Authors: Corr Serena , McClelland Innes , Booth Samuel G. , El-Shinawi Hany , Johnston Beth I.J , Cussen Edmund J. , Baker Peter J.
Published: July 2021

All solid-state batteries present highly promising opportunities for safer energy storage. High ionic conducting solid electrolytes may overcome some of the limitations of organic polymer electrolytes, where safety concerns limit the electrochemical stability window, to provide a way to increase energy densities in a safe manner. However, resistance to ion mobility across the solid-solid electrode-electrolyte interface remains a bottle-neck to be overcome in realising this technology. The synthetic approach employed can potentially influence conductivities (and hence battery performance) exhibited by solid electrolytes and this talk will detail our efforts to maximise these properties through developments in our synthetic and characterisation approaches. Recent synthetic results on systems such as the NASICONs and perovskites where electrodes and electrolytes with similar crystal structures are applied in an effort to lattice match across the interface, will be discussed. Comprehensive characterisation methods which employ multiple experimental techniques to simultaneously probe lithium-ion diffusion on different length and time scales will be presented, with particular attention to recently developed in situ muon spin relaxation measurements aimed at interrogating ion diffusion across the electrode-electrolyte interface. These results will showcase how careful synthetic design can enable performance and a comprehensive analysis provides greater insight into materials properties.
Characterization of Ion Association and Solvation in NaPF6 Carbonate Electrolytes
Authors: Suarez Sophia , Morales Daniel , Gomes Chagas Luciana , Paterno Domenec , Greenbaum Steve , Passerini Stefano
Published: July 2021

In this work we aimed to determine the ions association and solvation in electrolytes comprised of NaPF6 in binary EC:PC, and ternary 5EC:3PC:2DEC carbonate solvents. We studied their local and bulk transport properties through multi-Nuclear (1H, 19F and 23Na) Magnetic Resonance spin-lattice relaxation time (T1
) and self-diffusion coefficient (D) measurements. These studies were complemented with ionic conductivity and solution viscosity measurements. Results show several interesting features. Firstly, the Walden Product – which relates the molar conductivity and viscosity through a temperature-dependent constant – showed a dependence on temperature (see Figure 1). This suggested the dissociation of NaPF6 is dependent on temperature and is lower for the less polar electrolytes. Secondly, the sodium ions are preferentially solvated by PC molecules over EC. Thirdly, significant cation-anion association was observed for the less polar electrolytes. Lastly, this association was independent of temperature indicating that the temperature dependence of the Walden Product is primarily due to that of the viscosity. These results can aid in the improvement of ‘beyond lithium ion’ electrolytes for energy storage applications.

Figure 1
Revealing the Nanostructures of Liquid Electrolytes By X-Ray Scattering
Authors: Qian Kun , Winans Randall E. , Li Tao
Published: July 2021

The solution structure of the liquid electrolyte directly affects its ion migration ability and interfacial insertion chemistry, which ultimately determines the performance of batteries. Herein, small-angle X-ray scattering-wide angle X-ray scattering (SAXS-WAXS) is employed to investigate the diffuse structure of carbonate electrolytes containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium hexafluorophosphate (LiPF6), respectively. As the salt concentration increases, a upheave behavior is observed in both electrolyte systems at the high q part, which is caused by the cation-solvent interaction and charge ordering formation. Notably, at the low q part, we observe another gel polymer-like structure in the LiPF6 electrolyte system while the LiTFSI electrolytes do not have. It is believed that the anions cause this polymer-like structure, that is PF6- have strong hydrogen bonding ability than TFSI anions and, to some extent, cross-links solvent molecules. Raman, nuclear magnetic resonance (NMR), and molecular dynamics (MD) simulation further support the proposed structures. The structure-electrochemical performance relationship study suggests that LiPF6 electrolytes is more conducive to form stable SEI and reduce solvent-electrode side reactions. This work highlights the fundamental structure analysis in nanoscale, which will prompt better electrolytes in the future.
Impact of Sodium Vanadium Oxide (NaV3O8, NVO) Material Synthesis Conditions on Charge Storage Mechanism in Zn-Ion Aqueous Batteries
Authors: Tang Christopher , Singh Gurpreet , Housel Lisa M. , Kim Sung Joo , Quilty Calvin , Zhu Yimei , Wang Lei , Takeuchi Kenneth J. , Takeuchi Esther S. , Marschilok Amy C.
Published: July 2021

The electrochemical charge storage of sodium vanadate (NaV3O8 or NVO) cathodes in aqueous Zn-ion batteries has been hypothesized to be influenced by the inclusion of structural water for facilitating ion transfer in the material. Materials properties considered important (morphology, crystallite and particle size, surface area) are systematically studied herein through investigation of two NVO materials, NaV3O8· 0.34H2O [NVO(300)] and NaV3O8·0.05H2O [NVO(500)], with different water content, acicular morphologies with different size and surface area achieved via post-synthesis heat treatment. The electrochemistry of the two materials was evaluated in aqueous Zn-ion cells with 2 M ZnSO4 electrolyte using cyclic voltammetry, galvanostatic cycling, and rate capability testing. The thinner NVO(300) nanobelts (0.13 mm) demonstrate greater specific capacities and higher effective diffusion coefficients relative to the thicker NVO(500) nanorods. Notably however, while cells containing NVO(500) deliver lower specific capacity, they demonstrate enhanced capacity retention with cycling. The structural changes accompanying oxidation and reduction are elucidated via ex situ X-ray diffraction, transmission electron microscopy, and operando V K-edge X-ray absorption spectroscopy (XAS), where NVO material properties are shown to influence the ion insertion. Operando XAS verified that electron transfer corresponds directly to change in vanadium oxidation state, affirming vanadium redox as the governing electrochemical process.
Development of Graphene-Based Nanocomposites for Hydrogen Storage
Authors: Boateng Emamnuel , Chen Aicheng
Published: July 2021

Hydrogen economy is an envisioned approach with potential to addressing the increasing global energy consumption and emission issues. However, as one of the fundamental elements of the hydrogen economy, storage of hydrogen in a lightweight, compact, and safe manner remains the most serious bottleneck. Gaseous and liquid hydrogen storage methods continue to dominate for commercial usage; however, they have been found to be unsafe and expensive. Consequently, solid-state hydrogen storage has been attracting considerable interests, where hydrogen may be stored via physisorption (carbon-based materials and metal organic frameworks) or chemisorption (metal and complex hydrides) [1-3].

In this presentation, recent advances in graphene-based materials with a high surface area and enhanced storage capacity for solid-state hydrogen storage are highlighted. Specifically, this presentation focuses on the development of uniformly dispersed metal nanoparticles (NPs), for example Pd NPs, on a heteroatom-doped reduced graphene oxide (rGO). Our study has shown that the doping of the heteroatoms (such as boron, nitrogen etc.) effectively suppresses possible metal cluster formation, resulting in uniform distribution of the Pd NPs on the modified rGO. The effect of the doping of different heteroatoms and the decoration with Pd NPs on the hydrogen uptake and release is discussed.

[1] S. K. Konda, and A. Chen, Mater.
Today,
19, 100 (2016).

[2] E. Boateng, and A. Chen, Mater.
Today Adv., 6, 100022 (2020).

[3] E. Boateng, J. S. Dondapati, A. R. Thiruppathi, and A. Chen, Int.
J. Hydrogen Energy, 45, 28951 (2020).
(Invited) Nafion/CNT Passivated Carrier Selective Contacts for Silicon Photovoltaics
Authors: Chen Jianhui , Tune Daniel , Ge Kunpeng , Li Han , Flavel Benjamin S
Published: July 2021

In the past, the application of carbon nanotube-silicon solar cell technology to industry has been limited by the use of a metallic frame to define the active area in the middle of a silicon wafer. In our work, we use industry standard device geometries with a front- and back-junction design which allow for the entire wafer to be used as the active area. These are enabled by the use of an intermixed Nafion layer which simultaneously acts a passivation, antireflective and physical blocking layer as well as a nanotube dopant. This leads to the formation of a hybrid nanotube/Nafion passivated charge selective contact (PCSC) and solar cells with active areas of 1 – 16 cm2 are fabricated. Record maximum power conversion efficiencies of 15.2% and 18.9% are reported for front- and back-junction devices for 1 cm2 and 3 cm2 active areas, respectively. By placing the nanotube film on the rear of the device in a back-junction architecture many of the design related challenges for carbon nanotube silicon solar cells are addressed and their future application to industrialized processes are discussed.

Additionally, traditional silicon solar cells extract holes and achieve interface passivation with the use of a boron dopant and dielectric thin films such as silicon oxide or hydrogenated amorphous silicon. Without these two key components, few technologies have realized power conversion efficiencies above 20%. We now develop a carbon nanotube/Nafion ink that can be spin coated directly onto a silicon wafer to serve simultaneously as a hole extraction layer, but also to passivate interfacial defects. This enables a low-cost fabrication process that is absent of vacuum equipment and high-temperatures. Power conversion efficiencies of 21.4% on an device area of 4.8 cm2 and 20% on an industrial size (245.71 cm2) wafer are obtained.

[1] D. D. Tune, N. Mallik, H. Fornasier, B. S. Flavel, Adv. Energy Mater. 10, 2020, 1903261. DOI: 10.1002/aenm.201903261

[2] J. Chen, D. D. Tune, K. Ge, H. Li, B. S. Flavel, Adv. Funct. Mater. 2020, 30 2000484. DOI: 10.1002/adfm.202000484

[3] J. Chen, L. Wan, H. Li, J. Yan, J. Ma, B. Sun, F. Li, B. S. Flavel, Adv. Funct. Mater. 30, 2020, 202004476. DOI: 10.1002/adfm.202004476

[4] L. Wieland, H. Li, C. Rust, J. Chen, B. S. Flavel, Adv. Energy Mater. 2020 just accepted manuscript. DOI: 10.1002/aenm.202002880

Figure 1
(Invited) Foldable Perovskite Solar Cells Using Carbon Nanotube-Embedded Ultrathin Polyimide Conductor
Authors: Jeon Il , Maruyama Shigeo , Kauppinen Esko , Lee Phillip , Yoon Jungjin
Published: July 2021

Recently, foldable electronics technology has become the focus of both academic and industrial research. The foldable device technology is distinct from flexible technology, as foldable devices have to withstand severe mechanical stresses such as those caused by an extremely small bending radius of 0.5 mm. To realize foldable devices, transparent conductors must exhibit outstanding mechanical resilience, for which they must be micrometer-thin, and the conducting material must be embedded into a substrate. Here, a single-walled carbon nanotubes–polyimide composite film with a thickness of 7 μm is synthesized and used as a foldable transparent conductor in perovskite solar cells. During the high-temperature curing of the carbon nanotubes-embedded polyimide conductor, the carbon nanotubes are stably and strongly p-doped using MoOx, resulting in enhanced conductivity and hole transportability. The ultrathin foldable transparent conductor exhibits an sheet resistance of 82 Ω sq.-1 and transmittance of 80% at 700 nm, with a maximum-power-point-tracking-output of 15.2% when made into a foldable solar cell. The foldable solar cells can withstand more than 10,000 folding cycles with a folding radius of 0.5 mm. Such mechanically resilient perovskite solar cells are unprecedented; further they exhibit the best performance among the carbon-nanotube-transparent-electrode-based flexible solar cells.

Figure 1
(Invited) Thermoelectric Performance of Fermi-Level Tuned and Aligned Single Walled Carbon Nanotubes
Authors: Yanagi Kazuhiro
Published: July 2021

Thermoelectric power generation is one of important technologies for realization of highly efficient energy uses. Improvement of performance of thermoelectric materials is required, and theoretical studies suggest one-dimensional materials have potentials for the realization of the highest performance [1]. However, how 1D materials can really improve the thermoelectric performance has not been experimentally verified yet. In this context, thermoelectric properties of single walled carbon nanotubes attract a lot of attention because of their one-dimensional structure and electronic structures (See a review by Blackburn et al. [2]). Thermoelectric properties significantly depend on the electronic structures of SWCNTs, and relationships among Seebeck coefficient (S), electrical conductivity (σ), power factor, doping levels and their electronic structures have been revealed through various studies [3-5]. As a result, a very unique characteristics on thermoelectric properties of SWCNTs has been clarified [5]. In conventional materials, there is a trade-off between Seebeck coefficient and electrical conductivity, but in the metallic SWCNTs, the trade-off is broken because of the presence of 1D electronic structures, indicating the uniqueness of SWCNTs [5].

For the correct understanding of the thermoelectric performance, zT, in SWCNT thin films, clarification of the relationships among S,
σ, and thermal conductivity κ is very important. Although the relationships between S and σ have been well understood, the relationships among those parameters and κ have not yet. Avery et al. clarified κ is almost constant by the change of σ, and they estimated the zT value is approximately 0.01-0,05 [3]. Recently we developed a technique to clarify the cross-plane thermal conductivity κ
⊥ in SWCNT thin films with tuned Fermi level by a combination of time-domain thermoreflectance method and electrolyte gating technique [6], and then clarified that the κ
⊥ is almost constant even when in-plane σ is changed three order of magnitude from ~10 Sm-1 to 104 Sm-1 [5]. Such constant behavior of κ by the change of σ in SWCNT thin films is interesting in both basic science and application perspectives. Now we can prepare Fermi-level tuned and microscopically aligned SWCNT thin films [7], and the relationships between S and σ in the aligned directions have been clarified [8]. In this talk, I would like to discuss the recent results in our group and the estimated zT values of Fermi-level tuned and aligned SWCNTs.

References:

[1] Hicks& Dresselhaus, Phys. Rev. B 47, 16631 (1993), [2] Blackburn et al., Adv. Mater. 30, 1704386 (2018), [3]Avery et al., Nature energy 1, 1 (2016). [4] Yanagi et al., Nano Lett. 14, 6437 (2014), [5] Ichinose et al., Nano Lett. 19, 7370 (2019). [6] Ueji et al., Appl. Phys. Lett. 117, 133104 (2020). [7] Yanagi et al., Nature Comm. 9, 1121 (2018). [8] Fukuhara et al., Appl. Phys. Lett. 113, 243105 (2018).
Activated Carbon Derived from Biomass-Waste Okra As High-Performance Electrodes for Use in Supercapacitors
Authors: Oyedotun Kabir , Mirghn Abdulmajid , Oladepo Fasakin , Mahmoud Badr , Tarimo Delvina , Manyala Ncholu
Published: July 2021

The search for renewable, environmentally friendly, non-toxic and low-cost electrode materials possessing fast rate of electron/ion diffusion, top adsorption as well as tunable surface chemistry is greatly required for the growth of next-generation biocompatible energy storage devices [1]. In this study, a cost-effective, highly porous and environmentally-friendly carbon material was successfully developed from biomass waste okra (Hibiscus esculentum). Extensive characterization of the electrode material was achieved by employing various techniques. The material reveals distinct pore structures, surface areas and chemical properties, which were easily achieved by varying the activation agent/temperature. The optimized electrochemical performances especially in terms of improved capacitive performances and superior stability revealed by experimental results indicate the material’s potential applications as electrode for supercapacitors. The okra waste biomass-derived material’s beneficial capacitive properties make it a novel source of high-performance carbonaceous material electrode for supercapacitors application.
Carbon Nano-Onions As a Candidate for Efficient Energy Storage and Conversion
Authors: Shim Jae-Jin , Mohapatra Debananda , Dhakal Ganesh
Published: July 2021

Carbon nanostructures, such as carbon nano tubes (CNT), fullerene, graphene, and carbon nano-onions (CNO), have been getting tremendous attention during the last three decades. One of the major applications is energy storage and conversion. We have been studying CNT, graphene, and CNO for supercapacitors, sensors, and photocatalysts for the last ten years. Recently, the synthesis and application of pure CNO as well as heteroatom-doped CNO has been explored extensively. CNO is a multi-layered fullerene and has a unique concentric, multi-layer graphene microstructure. It is well suited for energy storage applications owing to its high electrical conductivity and small diffusion resistance. The exohedral pore structure of CNO provides easy access of electrolyte ions to its entire surface. The use of CNO in the negative electrode has been investigated for the application to the supercapacitors for the first time, outperforming the traditional activated carbon, CNTs, and graphene. CNO is not only compatible with metal oxides/sulfides but also with perovskite-based positive electrodes. CNO has also been studied for the dye-sensitized solar cells (DSSCs). The intrinsic hydrophilicity of the as-synthesized CNO eliminates the use of binders or additives as well as the harsh chemical activation process, unlike other carbon allotropes. The performance enhancement of the pristine CNO by doping with nitrogen, sulfur, or phosphorus has been observed for energy storage and photocatalysis.

Figure 1
Angiotensin II-induced overexpression of sirtuin 1 contributes to enhanced expression of Giα proteins and hyperproliferation of vascular smooth muscle cells
Authors: Hossain Ekhtear , Li Yuan , Anand-Srivastava Madhu B.
Published: July 2021

ANG II regulates various physiological functions including proliferation of VSMCs through the overexpression of Giα proteins. Sirt1, a class III histone deacetylase regulator, is implicated in several cellular functions, including VSMC growth and ANG II-induced hypertension. We showed for the first time that ANG II increased the expression of Sirt1, which through oxidative stress, growth factor receptor-mediated MAP kinase/Akt signaling pathway enhances the levels of Giα and cell cycle proteins resulting in the hyperproliferation of VSMCs.
Water Saving Control of Turfgrass Irrigation Robot Using Genetic Simulated Annealing Algorithm
Authors: Han Bei
Published: July 2021

Artificial intelligence through the robotic system offers a solution to the quest for an autonomous system with high cutting efficiency for lawn mowing. Because of the current trimming and maintenance operations on grasslands and gardens, it is essential to develop autonomous and efficient lawn pruning electromechanical equipment. This paper describes the design and construction of a high-performance automated grass trimming and irrigating robot. This device cuts and irrigates grass automatically with little human intervention. A genetic simulated annealing algorithm was employed to optimize motor parameters, specifically design a set of mowing mechanisms and mowing height adjustment system. The prototype was tested, which mainly includes the running status evaluation of the walking module, the mowing module, the cutter head lifting module, and the collision detection module. This robot can save water while watering the lawns, reduce labor costs, and improve mowing efficiency. We note that the proposed system can be implemented on a large scale under natural conditions in the future, which will be helpful in robotics applications and cutting grass on lawns and playing grounds.
Porous Silk Scaffold Derived from Formic Acid: Characterization and Biocompatibility
Authors: Zhang Ting , Xiong Qianwei , Shan Yuxi , Zhang Feng , Lu Shijun
Published: July 2021

Silk porous scaffold possesses 3D space structure for cell adhesion and tissue growth and demonstrates promising applications in biomedical engineering. In this study, a porous silk scaffold was prepared from formic acid, and its morphology, structure, mechanical properties, and biocompatibility were characterized. The preparation process involved silk dissolution in formic acid and salt leaching in water, avoiding widely used organic solvent‐induced crystallization including methanol or ethanol. The resulting porous silk scaffolds showed good pore structure, stable silk II crystalline structure, good mechanical properties, and enhanced cell biocompatibility. Therefore, these findings demonstrate that porous silk scaffold derived from formic acid has great potential applications as 3D scaffold for cell culture and tissue repair.
An Experimental Study on the Creep Characteristics of Sandstone in the Interval of Different Critical Stresses
Authors: Yang Chao , Dong Xingchen , Xu Xuan , Sun Qiancheng
Published: July 2021

Creep tests on brittle sandstone specimens were performed to investigate the time‐dependent characteristics in the interval of different critical stresses. The results showed that failure will not occur when the loaded stress σ1 is less than the critical stress of dilation σcd, while all specimens were destroyed when σ1 is larger than σcd. In addition, the value of σcd was very close to the long‐term strength obtained by the method of the isochronous stress‐strain curve. Therefore, σcd can be regarded as the long‐term strength of the sandstone specimens. When σ1 is larger than σcd, the time required for the failure of specimen tf decreases with the increase of σ1; the creep rate dε/dt increases with time t, and the specimen will be destroyed when it reaches a maximum value (dε/dt)max. Both relationships tf and σ1 and (dε/dt)max and σ1 can be described by the exponential function. Then, a nonlinear damage creep model considering the deformation damage and strength damage in the interval of different critical stresses was established, which can describe the whole creep process and predict the failure time of sandstone specimens.
Numerical and Experimental Approach for Failure Analysis of Soil Subjected to Surface Explosion Loading
Authors: Wang Iau-Teh
Published: July 2021

Controlling the hazards to facilities caused by detonation waves is a high priority in engineering design. To protect an underground facility, soil can reduce the destructive effects of detonation waves. Soil dynamic characteristics and the area of the destructive zone are affected by shock wave energy. The material at ground zero is impacted by high‐intensity stress and forms a crater. To ensure the safety of the facility, the protective soil layers must be sufficiently thick. Therefore, the purpose of this study was to analyze the destructive effects that caused the deformation and destruction of an external protective soil layer. The results of the explosion experiments and the numerical simulation analysis were compared to explore the dynamic characteristics of the soil affected by the shock wave and the crater effects of on‐ground explosions. The analysis model adopted an 8‐node hexahedral element to create a three‐dimensional solid structure model of the fluid‐solid interaction. The material failure analysis demonstrated that the detonation wave destabilized the interior of the soil body, and the nearby high‐intensity stress was the key factor for material failure. The results can serve as a reference for the design of soil‐covering layers that provide explosion hazard control.
Adaptive Proportional Integral Observer Design for Interval Type 2 Takagi–Sugeno Fuzzy Systems
Authors: Khedher Atef , Elleuch Ilyes , BenOthman Kamal
Published: July 2021

In this paper, the problem of fault estimation in systems described by Takagi–Sugeno fuzzy systems is studied. A proportional integral observer is conceived in order to reconstruct state and faults which can affect the studied system. Proportional integral observer can easily estimate actuator faults which are assimilated to be as unknown inputs. In order to estimate actuator and sensor faults, a mathematical transformation is used to conceive an augmented system, in which the initial sensor fault appears as an unknown input. Considering the augmented state, it is possible to conceive an adaptive observer which is able to estimate the whole state and faults. The noise effect on the state and fault estimation is also minimized in this study, which provides some robustness properties to the proposed observer. The proportional integral observer is conceived for nonlinear systems described by Takagi–Sugeno fuzzy models.
New-Onset Diabetes with Ketoacidosis Precipitated by COVID-19 in Children: A Report of Two Cases
Authors: Chekhlabi Nabila , Haoudar Amal , Echcharii Nadia , Ettair Said , Dini Nezha
Published: July 2021

Background and Aims. There is growing evidence that the 2019 coronavirus disease (COVID-19) is emerging as a potential trigger virus for the development of diabetes mellitus in children. This can occur even in patients without factors predisposing to impaired glucose metabolism. Here, we report two rare cases of diabetic ketoacidosis revealing new-onset diabetes and precipitated by COVID-19. These cases are reported in view of their rarity and originality. The relationship between type 1 diabetes mellitus and COVID-19 is discussed. Results. Two children developed symptoms suggestive of diabetic ketoacidosis preceded by polyuria, polydipsia, and asbestos. There is a documented COVID-19 infection in the parents of the 2 children. An asymptomatic infection was detected in the 2 patients on the basis of a reverse transcription polymerase chain reaction (RT-PCR) test. Thoracic imaging and inflammatory workup were negative in both cases. Both patients responded well to treatment, including rehydration regimens and intravenous insulin. On the 2nd day of their hospitalization, they were transferred to several injections of subcutaneous insulin with therapeutic and nutritional education from the parents. After about 4 weeks, their insulin requirements probably decreased due to the diabetes honeymoon. Conclusion. COVID-19 can induce acute onset diabetes and diabetic ketoacidosis in children. More research data are needed to improve our knowledge of this constellation and to guide the most appropriate therapies.
The Application of Statistical Parametric Mapping to Evaluate Differences in Topspin Backhand between Chinese and Polish Female Table Tennis Players
Authors: Bańkosz Ziemowit , Winiarski Sławomir
Published: July 2021

The research is aimed at comparing the kinematics (the movement pattern in the most important joints and accelerations of the playing hand) between female table tennis players coached in Poland (POL) and China (CHIN) during the performance of a topspin backhand stroke (so-called quick topspin). The study involved six female table tennis players at a high sports skill level, playing in Poland’s highest league. Three were national team members of Poland (age:

20.3
±
1.9

), while the other three were players from China (age:

20.0
±
0.0

). Kinematics was measured using MR3 myoMuscle Master Edition system—inertial measurement unit (IMU) system. The participants performed one task of topspin backhand as a response to a topspin ball, repeated 15 times. Statistical parametric mapping (SPM) was calculated using SPM1D in a Python package that offered a high-level interface to SPM1D. The SPM method allowed for the determination of differences between the Chinese and Polish female athletes. The differences found are probably mainly due to differences in the training methodologies caused by different coaching systems. The observed differences include, among others, greater use of the so-called small steps in order to adapt and be ready during the back to ready position and backswing phases, which gives the CHIN players slightly better conditions for preparation for the next plays. The CHIN players’ position compared to that of the POL players favours a quicker transition from the backhand to the forehand play. This difference is probably related to the difference in the dominant playing styles of the groups studied. Despite the differences in movement patterns in both groups, the exact value of playing hand was achieved. This may be a manifestation of the phenomenon of equifinality and compensation. All the differences found are probably mainly due to differences in the training methodologies caused by different coaching systems.
Severe Hemolysis in a COVID-19 Patient with Paroxysmal Nocturnal Hemoglobinuria
Authors: Otieno Steve Biko , Altahan Alaa , Kaweeta Fnu , Karri Saradasri , Alnoor Fnu , Johnson Robert
Published: July 2021

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), has been demonstrated to be able to activate complement, making patients with deficiency in negative complement regulation, such as paroxysmal nocturnal hemoglobinuria (PNH), particularly vulnerable to complement-mediated cell damage. We report a case of a patient who presented with fatigue, facial swelling, and upper respiratory infection (URI) symptoms and was found to have COVID-19 with laboratory tests showing severe hemolysis and pancytopenia secondary to PNH.
A Survey of User Authentication Based on Channel State Information
Authors: Wang Zhengjie , Dou Wenwen , Ma Mingjing , Feng Xiaoxue , Huang Zehua , Zhang Chengming , Guo Yinjing , Chen Da
Published: July 2021

Recently, human behavior sensing based on WiFi channel state information has drawn more attention in the ubiquitous computing field because it can provide accurate information about the target under a device‐free scheme. This paper concentrates on user authentication applications using channel state information. We investigate state‐of‐the‐art studies and survey their characteristics. First, we introduce the concept of channel state information and outline the fundamental principle of user authentication. These systems measure the dynamic channel state information profile and implement user authentication by exploring the channel state information variation caused by users because each user generates unique channel state information fluctuations. Second, we elaborate on signal processing approaches, including signal selection and preprocessing, feature extraction, and classification methods. Third, we thoroughly investigate the latest user authentication applications. Specifically, we analyze these applications from typical human action, including gait, activity, gesture, and stillness. Finally, we provide a comprehensive discussion of user authentication and conclude the paper by presenting some open issues, research directions, and possible solutions.
COVID-19: Moral and Ethical Implications for Orthopaedic Spine Surgeons
Authors: Min Cris J. , Iturriaga Cesar , Wang Victoria , Verma Rohit
Published: July 2021

The rapid spread of COVID-19 has made a significant impact on healthcare systems worldwide, with a large influx of patients prompting the cancellation of elective surgery in order to conserve resources and prevent the risk of exposure to the novel virus. In this case report, we present a 66-year-old male patient, with a history of cerebral palsy and developmental disabilities, exhibiting an increasing loss of function over the course of 10 days amid the COVID-19 pandemic. The patient was initially refused transport to the hospital by emergency medical services and later transported per independent request from his surgeon. Upon admittance to the hospital, the patient was found to have severe spinal cord compression with myelopathic symptoms and underwent an anterior cervical discectomy and fusion. This case highlights the need for more specific guidelines regarding the evaluation of a spinal injury by EMS and the hospital system amid a national crisis.
Hierarchical Task Assignment Strategy for Heterogeneous Multi-UAV System in Large-Scale Search and Rescue Scenarios
Authors: Chen Jie , Xiao Kai , You Kai , Qing Xianguo , Ye Fang , Sun Qian
Published: July 2021

For the large-scale search and rescue (S&R) scenarios, the centralized and distributed multi-UAV multitask assignment algorithms for multi-UAV systems have the problems of heavy computational load and massive communication burden, which make it hard to guarantee the effectiveness and convergence speed of their task assignment results. To address this issue, this paper proposes a hierarchical task assignment strategy. Firstly, a model decoupling algorithm based on density clustering and negotiation mechanism is raised to decompose the large-scale task assignment problem into several nonintersection and complete small-scale task assignment problems, which effectively reduces the required computational amount and communication cost. Then, a cluster head selection method based on multiattribute decision is put forward to select the cluster head for each UAV team. These cluster heads will communicate with the central control station about the latest assignment information to guarantee the completion of S&R mission. At last, considering that a few targets cannot be effectively allocated due to UAVs’ limited and unbalanced resources, an auction-based task sharing scheme among UAV teams is presented to guarantee the mission coverage of the multi-UAV system. Simulation results and analyses comprehensively verify the feasibility and effectiveness of the proposed hierarchical task assignment strategy in large-scale S&R scenarios with dispersed clustering targets.
Investigation on Physicomechanical Properties and Constitutive Model of Tuff in Mila Mountain Tunnel under Dry and Saturated Conditions
Authors: He Zhihao , Pei Xiangjun , Cui Shenghua , Sun Wentai , Luo Luguang , He Chengruiwei
Published: July 2021

Many tunnel engineering accidents are generally caused by water softening tuff of high porosity. Experimental and theoretical analytical methods, including rock ultrasonic testing, X‐ray diffraction (XRD), microscopic observation, uniaxial compression test, and scanning electron microscope (SEM), are employed to analyze the physicomechanical properties of tuff in Mila Mountain tunnel under dry and saturated conditions. Then, the mechanism of tuff softening in water is explained. Finally, the statistical damage constitutive model of tuff is established. It was revealed that the tuff compositions were dominated by quartz and clay minerals accounting for more than 90%, and clay minerals, anhydrite, and pyrite were mainly soluble minerals. After being saturated with water, the soluble minerals in the tuff are dissolved, and the porosity and wave velocity are increased; however, the elastic modulus and peak strength are decreased, indicating that water softening was distinct. Water softening after saturation was due to the mineral compositions and microstructure characteristics of tuff in Mila Mountain tunnel; specifically, as the tuff characterized by high porosity was conductive to water absorption, the soluble minerals in the tuff were corroded and swelled by water, dissolving, loosening, and softening the tuff structure; then, its mechanical behavior was degraded. It was demonstrated by the experimental results consistent with theoretical results that the model can be employed to express the constitutive behavior of tuff in Mila Mountain tunnel under dry and saturation conditions. The findings provide insights into macroscale deterioration of tuffs and theoretical knowledge for the tunnel excavation and support of Mila Mountain tunnel.
Influence of Confining Pressure Unloading Rate on the Strength Characteristics and Fracture Process of Granite Using Lab Tests
Authors: Guo Jiaqi , Liu Pengfei , Fan Junqi , Shi Xiaoyan , Huang Xin
Published: July 2021

In order to study the mechanical behaviors and fracture process properties of granite under confining pressure unloading with constant axial pressure, RMT‐150B rock mechanics test system and acoustic emission detector were used to study the mechanical properties and fracture process characteristics of deeply buried granite specimens under different combinations of initial confining pressures and unloading rates. The results show that when the unloading rate is small, the deviatoric stress‐strain curve of granite specimens will yield an unloading platform, and the specimens show significant characteristics of ductility; when the unloading rate is large, the specimens show characteristics of brittleness. Besides, the axial strain rate increases with the increase of initial confining pressure and unloading rate, and the axial strain rate fluctuates. The ratio of axial strain increment to confining pressure increment of granite specimens decreases with the increase of the unloading rate, and a faster unloading rate and a higher initial confining pressure will restrain the axial deformation of granite sample. The normalized confining pressure decreased parameter of granite specimen increases with the increase of initial confining pressure. When the unloading rate is relatively high, it plays a dominant role in the compressive strength of granite specimens. The Mohr–Coulomb strength criterion can better reflect the strength characteristics of specimens under confining pressure unloading. The cohesion of granite specimens decreases with the increase of unloading rate, and the internal friction angle increases with the increase of unloading rate. Notably, the unloading rate presents a weakening effect on the cohesion of the specimen and a strengthening effect on the internal friction angle of the specimen, and the former effect is stronger than the latter one. When the unloading rate is small, the acoustic emission ringing count increases more evenly, and the deformation and damage of the specimen develop slowly; when the unloading rate is high, the acoustic emission ringing count increases to the maximum instantaneously at the initial stage of confining pressure unloading, and the specimen is damaged rapidly, showing the characteristic of sudden fracture. The fracture mode of granite specimens is affected by the unloading rate and initial confining pressure. At the same unloading rate, the specimens with high initial confining pressure show typical tensile fracture characteristics, while the specimens with low initial confining pressure mainly suffer from shear fracture or shear‐tension composite fracture. With the increase of unloading rate, the fracture characteristics of specimens show a transition from shear or shear‐tension composite fracture to tensile fracture.
An Evolutionary Approach for the Enhancement of Dermatological Images and Their Classification Using Deep Learning Models
Authors: Chaahat  , Kumar Gondhi Naveen , Kumar Lehana Parveen
Published: July 2021

Dermatological problems are the most widely spread skin diseases amongst human beings. They can be infectious, chronic, and sometimes may also lead to serious health problems such as skin cancer. Generally, rural area clinics lack trained dermatologists and mostly rely on the analysis of remotely accessible experts through mobile-based networks for sharing the images and other related information. Under such circumstances, poor image quality introduced due to the capturing device results in misleading diagnosis. Here, a genetic-algorithm- (GA-) based approach used as an image enhancement technique has been explored to improve the low quality of the dermatological images received from the rural clinic. The diagnosis is performed on the enhanced images using convolutional neural network (CNN) classifier for the identification of the diseases. The scope of this paper is limited to only motion blurred images, which is the most prevalent problem in capturing of the images, specifically when any of the two (device or the object) may move unpredictably. Seven types of skin diseases, namely, melanoma, melanocytic nevus, basal cell carcinoma, actinic keratosis, benign keratosis, vascular lesion, and squamous cell carcinoma, have been investigated using ResNet-152 giving an overall accuracy of 87.40% for the blurred images. Use of GA-enhanced images increased the accuracy to 95.85%. The results were further analyzed using a confusion matrix and t-test-based statistical investigations. The advantage of the proposed technique is that it reduces the analysis time and errors due to manual diagnosis. Furthermore, speedy and reliable diagnosis at the earliest stage reduces the risk of developing more severe skin problems.
An Averaging Principle for Mckean–Vlasov-Type Caputo Fractional Stochastic Differential Equations
Authors: Wang Weifeng , Yan Lei , Hu Junhao , Guo Zhongkai
Published: July 2021

In this paper, we want to establish an averaging principle for Mckean–Vlasov-type Caputo fractional stochastic differential equations with Brownian motion. Compared with the classic averaging condition for stochastic differential equation, we propose a new averaging condition and obtain the averaging convergence results for Mckean–Vlasov-type Caputo fractional stochastic differential equations.
[Retracted] Effects of Xuefu Zhuyu Granules on Patients with Stable Coronary Heart Disease: A Double‐Blind, Randomized, and Placebo‐Controlled Study
Authors: Li Yuzhen , Tao Tianqi , Song Dandan , He Tao , Liu Xiuhua
Published: July 2021

Despite advances in the drug treatment strategy for stable coronary heart disease (CHD), the mortality of CHD continues to rise. New or adjuvant treatments would be desirable for CHD. Xuefu Zhuyu granules are derived from the formula of traditional Chinese medicine. To determine whether Xuefu Zhuyu granules might have adjuvant effects on stable CHD, we conducted a controlled clinical trial. Patients with stable CHD were enrolled and randomly assigned to receive Xuefu Zhuyu granules or placebo for 12 weeks in addition to their standard medications for the treatment of CHD. The primary endpoints comprise the Canadian Cardiovascular Society Angina Grading Scale (CCS class), echocardiographic measures, Seattle Angina Questionnaire (SAQ), and coronary artery CT. The secondary endpoints included the parameters of nailfold capillary measurement and cutaneous blood perfusion (CBP). After 12 weeks of follow‐up, there was a great improvement of the Canadian Cardiovascular Society Angina Grading Scale (CCS class) in the Xuefu Zhuyu group compared with the placebo group (p < 0.01). Also, a decrease was found in the percentage of patients with CCS class II in the Xuefu Zhuyu group between follow‐up at 12 weeks and baseline (p < 0.01). We observed a significant increase in SAQ scores of physical limitation (p < 0.01) and treatment satisfaction (p < 0.05) in patients receiving Xuefu Zhuyu treatment at 12 weeks in comparison with those at baseline, but not in placebo treatment (p > 0.05). Amelioration in coronary artery stenosis in the Xuefu Zhuyu group was noted (p < 0.05). Xuefu Zhuyu granule treatment led to great improvements in cutaneous blood perfusion at follow‐up of 12 weeks compared with placebo (p < 0.05). These findings suggest that on a background of standard medications, Xuefu Zhuyu granules have the ability to further improve the prognosis of patients with stable CHD.
Research on Edge Service Composition Method Based on BAS Algorithm
Authors: Du Zhoujie , Miao Huaikou
Published: July 2021

Edge services are transferred data processing, application running, and implementation of some functional services from cloud central server to network edge server to provide services. Combined edge service can effectively reduce task computation in the cloud, shorten transmission distance of processing data, quickly decompose task of service request, and select the optimal edge service combination to provide service for users. BAS is an efficient intelligent optimization algorithm, which can achieve efficient optimization and neither need to know the specific form of function nor need gradient information. This paper designs an edge service composition model based on edge computing and proposes a method about edge service composition by BAS optimization algorithm. Our proposed method has obvious advantages in service composition efficiency compared with service composition method based on PSO or WPA heuristic algorithm. Compared with cloud service composition method, our proposed method has advantages of shorter service response time, low cost, and high quality of user experience.
Subdivision of Urban Traffic Area Based on the Combination of Static Zoning and Dynamic Zoning
Authors: Luo Jing , Zhang Qingnian
Published: July 2021

In this paper, the traffic area of subzone division in urban road network is studied and a subzone division method based on the combination of static partition and dynamic partition is proposed. The static partition is carried out for the road network when the traffic flow is in a noncongested state, so as to provide the decision-making basis for the traffic green wave signal control strategy. At the same time, aiming at the road network when the traffic flow is congested, the dynamic partition is carried out on the basis of static partition to provide the decision-making basis for the traffic maximum flow signal control strategy. In view of the fact that it is difficult to determine the clustering center point during the initial division, this method proposes to determine the clustering center point according to the value of nodes of betweenness centrality. In order to solve the problem that it is difficult to collect traffic data, a method for estimating traffic flow density is proposed. In order to solve the problem of normalization of different probability distribution among various parameters, Mahalanobis distance is used as the fusion index of subzone division. Model verification shows that the method is feasible and effective.
Optical and Photocatalytic Properties of CuxS/ZnO Composite Thin Films Deposited by Robotic Spray Pyrolysis Deposition
Authors: Yepseu Adrien P. , Isac Luminita , Nyamen Linda D. , Cleymand Franck , Duta Anca , Ndifon Peter T.
Published: July 2021

This article reports on VIS-active composite thin films based on zinc oxide (ZnO) and copper sulfide (CuxS) deposited using robotic spray pyrolysis deposition (SPD) for the study of the optical and photocatalytic properties. The first step involves the SPD deposition of a CuxS layer onto the glass substrate at 300°C. The second step consists of the deposition of a ZnO layer onto the CuxS layer to form glass/CuxS-ZnO composites that were further annealed at 400°C. The development of the composite thin films was confirmed by XRD and EDX analyses. The band gap energy (

E

g

) of the bare ZnO thin films decreased from 3.15 eV to an activation energy value of 2.8 eV after the deposition of the ZnO thin layer onto the CuxS layer and from 2.8 to 2.08 eV after annealing the CuxS-ZnO composite at 400°C. The UV-VIS irradiation (5.5% of UV,

G
=
55
 
W
/

m

2

) of a 10 ppm methylene blue solution was used to investigate the photocatalytic properties of the CuxS-ZnO composites. The annealed CuxS-ZnO thin films at 400°C demonstrates better photocatalytic activity compared to CuxS-ZnO composites deposited at 300°C. The enhanced photocatalytic efficiency of the annealed CuxS-ZnO thin films may be the result of the diode structure and the increased crystallinity that prevent the electron-hole recombination.