bluuebunny/crossref_metadata_2025 huggingface dataset:
Fourier‐based effective permeability for transformer iron losses computation under saturation
Authors: Wang Wei , Nysveen Arne , Magnusson Niklas , Nilssen Robert
Published: February 2021

Computation of iron losses in transformers requires significant numerical efforts, particularly under magnetic saturation when the magnetic non‐linearity needs to be considered. This study proposes a Fourier method to calculate the magnetic flux density used for the iron loss evaluation in transformers under saturation. It includes pre‐processing of the non‐linear material. A permeability frequency spectrum is obtained from Fourier analysis, where the fundamental part is used as a magnetisation definition and the harmonic components are used for core loss calculation. The proposed method offers a time‐efficient tool to calculate core loss under various saturation levels and non‐sinusoidal excitation currents. The influence of the definition of the core material on the leakage field and the stray loss calculation is studied and compared with existing methods. The proposed methods have been implemented and validated in two‐ and three‐dimensional finite‐element models with isotropic and anisotropic cores. The results yield accuracy comparable to that of a time‐domain calculation. Furthermore, the influences of various effective permeability methods on the leakage field and the associated stray loss are compared and discussed.
Rule‐based operation task‐aware energy management for ship power systems
Authors: Hein Kyaw , Xu Yan , Senthilkumar Yuvarekha , Gary Wilson , Gupta Amit Kumar
Published: February 2021

This study proposes an operation task‐aware energy management strategy for ship power systems that consist of main engines, diesel–electric engines, and energy storage systems. The proposed strategy aims to meet the fuel consumption and task‐dependent objectives of the vessel by optimally dispatching the generation and storage units. Firstly, rule‐based decisions are made based on the operational task requirements and specifications by the classification societies. Then, in the optimisation stage, these decision variables are used as inputs to formulate and update the operational constraints and the objectives of the optimisation. The optimisation problem is formulated as a mixed‐integer linear programming model, and with the help of rule‐based decision variables, the problem can be efficiently solved by the exhaustive search algorithm. Four case studies with different operation task sequences and ship topologies are performed to demonstrate the effectiveness of the dispatching scheme. Furthermore, the results indicate the simplicity and practicality for the actual implementation, as well as flexibility and applicability of the proposed optimal energy dispatch for different types of vessels.
Estimation of link‐cost function for cyclists based on stochastic optimisation and GPS traces
Authors: Schweizer Joerg , Rupi Federico , Poliziani Cristian
Published: February 2021

The objective of this work is the calibration of a generalised cost function for the bicycle network links to be used in conjunction with assignment methods for uncongested networks, as cyclists are generally much less delayed by traffic congestions with respect to auto‐traffic. The calibration's goal is to find a coefficient vector for a linear link‐cost function that maximises the overlap between routes obtained with a minimum cost routing of cyclists' demand and the relative cyclists' chosen routes, identified by a map‐matching procedure of recorded global positioning system (GPS) traces. The calibration focuses on minimising an objective function through different established evolution‐based optimisation algorithms, thus avoiding the generation of route choice sets. Link cost functions are calibrated for a modified Openstreet network of Bologna, Italy, using GPS data from the European cycling challenge and Bella Mossa campaign. Results show an improvement of up to 30% of overlapping routes with respect to pure distance‐based routing. It is also demonstrated that the calibrated link‐costs are transferable to a different scenario.
Magnetic flux density analysis of series resonant converter operating in discontinuous conduction mode for high‐voltage high‐power applications
Authors: Ning Guangfu , Chen Wu , Ling Yanbo , Su Mei , Xu Guo
Published: February 2021

Due to its zero‐current switching characteristic, the series resonant converter operating in discontinuous conduction mode (DCM‐SRC) is suitable for high‐voltage high‐power applications. To meet the requirement of a wide output voltage range, the pulse frequency modulation with constant on‐time can be adopted for DCM‐SRC. By comparing the resonant capacitor voltage with input voltage, it is first discovered that there are two different operation cases with different magnetic flux density (MFD) values for the transformer core. The boundary conditions for the two cases are revealed, and the exact maximum MFD (MMFD) expression of each case is derived. According to the obtained expressions, the MMFD has the smallest value under the lowest switching frequency and increases with the increase of switching frequency for both cases, indicating that the high‐power transformer can be designed at the highest switching frequency. The fundamental cause of higher MMFD case is derived according to the in‐depth analysis of resonant capacitor voltage. Moreover, a transformer turns ratio design guideline can be easily obtained to reduce the MMFD. Both the simulation model and laboratory prototype are established for verification, and the results show that the theoretical analysis is convincing.
EMI filter design for single‐phase grid‐connected inverter with noise source impedance consideration
Authors: Liu Yitao , Ye Xin , Peng Jianchun
Published: February 2021

It is well known that noise source impedance plays a significant role in designing conducted electromagnetic interference (EMI) filters. However, the noise source impedance in a switched‐mode power supply is not easy to extract. In this study, the noise source impedance in a single‐phase inverter is extracted under operating conditions based on a two‐probe approach. First, the noise source modelling and analysis are implemented for the inverter system to illustrate the importance of impedance. Furthermore, the proposed two‐probe method is introduced and then validated by several passive components. Proper and straightforward premeasurement calibrations are needed to eliminate the influence of the probes and cables. The approach can accurately extract the common‐mode and differential‐mode noise source impedances with different configurations according to the characteristics of their propagation paths. Compared with a traditional EMI filter design, the experimental results show that the one designed by the proposed approach can effectively attenuate the conducted EMI noises to meet the requirements with more appropriate and optimised parameters.
Series‐connected 36‐pulse rectifier using a hybrid harmonic injection method
Authors: Meng Fangang , Li Taiqi , Wang Lin , Gao Lei
Published: February 2021

This study proposes a hybrid voltage harmonic injection circuit at the DC link of the traditional series‐connected 12‐pulse rectifier to improve the harmonic suppression performance of the rectifier, which contains an injection transformer and the auxiliary circuit. The optimum turn ratio of the injection transformer and the optimal conduction angle of the switch are designed from the viewpoint of minimising the total harmonic distortion (THD) of the input voltage in the isolated transformer. Under the optimal design, the proposed series‐connected rectifier operates as a 36‐pulse rectifier. Experimental results indicate that the THD of input voltage reduces to ∼3.19% and that of the input current is only ∼2%.
Integration of renewable energy sources with LCC HVDC system using a new circuit topology with DC fault ride‐through capability
Authors: Cherian Mathew Ebin , Das Anandarup , Sharma Rahul
Published: February 2021

The integration of remote renewable energy sources located near the long‐distance HVDC transmission corridor to the HVDC system is an active area of research. This study presents a new fault‐tolerant scheme using a modular soft‐switched DC–DC converter with high‐voltage gain to integrate renewable energy sources to LCC‐based HVDC systems. The configuration, operating principle and mathematical modelling of the new DC–DC converter are described in this study. As both the charging and discharging processes takes place through resonant circuits, zero current switching of all the switches used in the converter is achieved. The proposed scheme has the inherent fault‐tolerant capability and enables fast recovery from commutation failures in the main LCC HVDC system. The operation of the proposed scheme during various fault scenarios is analysed and explained in this study. The performance of the proposed scheme and its fault ride though the capability is verified using a simulation model built in PSCAD/EMTDC and an experimental prototype.
Monitoring of subsynchronous oscillation in a series‐compensated wind power system using an adaptive extended Kalman filter
Authors: Shair Jan , Xie Xiaorong , Yuan Liang , Wang Yanhui , Luo Yongzhi
Published: February 2021

The characteristics of subsynchronous oscillation (SSO) in series‐compensated wind power systems are significantly affected by the system's operating condition. Besides the variation in the magnitude and frequency of the SSO during an SSO event, the fundamental frequency may also deviate from its nominal value. This study aims at capturing the dynamics of both subsynchronous and fundamental frequency components simultaneously. This work first explores the strengths and weaknesses of various Kalman filtering based frequency tracking algorithms for joint tracking of the fundamental and SSO components. Then, it proposes a novel adaptive extended Kalman filtering (AEKF) algorithm, in which the process noise covariance is updated online by maximising the probability density function of the predicted error. The process noise covariance factor changes to positive non‐zero value whenever the frequency of the fundamental component deviates. Thus, the proposed AEKF extracts the time‐varying subsynchronous component while also tracking the small variations in the fundamental frequency. The tracking performance of the AEKF is validated on computer‐generated test signals as well as on the electromagnetic transient simulation model of an actual wind power system facing SSO. The captured fundamental and subsynchronous dynamics can be used for designing monitoring, protection, and control schemes for the SSO.
Economical operation strategy of an integrated energy system with wind power and power to gas technology – a DRL‐based approach
Authors: Zhang Bin , Hu Weihao , Cao Di , Huang Qi , Chen Zhe , Blaabjerg Frede
Published: February 2021

With the rapid development of artificial intelligence, adopting advanced deep reinforcement learning (DRL) methodologies to solve the optimisation problem in power systems has become more effective. This study proposes a novel energy control method associated with DRL to solve the economical optimisation problems in an integrated energy system with wind power and power‐to‐gas technology. To consider the randomness of wind power and the flexibility of upper‐level energy prices, the economical optimisation problem is formulated as a finite Markov decision‐making process. Cycling decay learning rate deep deterministic policy gradient (CDLR‐DDPG) algorithm is proposed to obtain the optimal operation strategy. A comparison among different benchmark methods is provided to demonstrate the superiority of CDLR‐DDPG algorithm in optimising an economical problem for the considered system.
Functionalisation of MWCNTs with piperazine and dopamine derivatives and their potential antibacterial activity
Authors: Hussain Saghir , Mahmood Ansari Tariq , Sahar Hina , Kanwal Shamsa , Mansoor Farrukh , Darak Timur , Iqbal M. Zubair , Khurshid Butt Fahim , Hussain Ajaz , Muhammad Aun , Zaman Sher , Hasnain Tariq Ghulam , Muhammad Asif Hafiz
Published: February 2021

Functionalised multi‐walled carbon nanotubes (MWCNTs) are exclusively used in antibacterial activity due to their high aspect ratio and surface penetration characteristics. This study reports the synthesis of piperazine and dopamine functionalised MWCNTs to investigate antibacterial activity against strains like Staphylococcus aureus and Micrococcus luteus. MWCNTs were activated through acid oxidation and then refluxed at 75°C for 10 and 8 h in the presence of piperazine and dopamine, respectively. The functionalised MWCNTs were characterised by scanning electron microscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction and Raman spectroscopy. Moreover, functionalised MWCNTs were subjected to zone inhibition assay on agar plates. Results revealed the significant antibacterial activity against various bacteria up to 50%. Similarly, it was observed that the effect of different solvents, such as dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) was non‐prevalent to the bacterial zone of inhibition. Such facile nano‐modifications provide passage to nano‐antibacterials for advanced studies.
Synthesis and investigation of dielectric properties of nanoceramic composite material for microwave applications
Authors: Siragam Srilali , Dubey Raghvendra S. , Pappula Lakshman
Published: February 2021

This Letter reports the synthesis of nanoceramic composite ZnAl2O4TiO2 by using a cost‐effective and straight forward sol–gel route. X‐ray diffraction (XRD) showed the ZnAl2O4 cubic structure along with the mixed anatase‐ and rutile‐phases of TiO2. Rietveld refinement is performed using XRD pattern to study the structural parameters. Raman investigation endorsed the corresponding vibration peaks of TiO2 and ZnO. Field‐emission scanning electron microscopy evidenced the agglomerated spherical nanoparticles. Energy‐dispersive spectroscopy analysis demonstrated the elementary peaks of Zn, Al, and Ti at 4.5, 1.5, and 1 eV, respectively. LCR measurement revealed the decreased dielectric permittivity with the rise in frequency and temperature. This dielectric characteristic is attributed to the dipole movement of the charge carriers. Furthermore, the authors present the investigation of the conductivity and impedance of the prepared dielectric ceramic material.
Facile precipitation synthesis of extraordinary visible‐light‐driven BiOXs photocatalyst
Authors: Guo Xiya , Li Lun , Zhu Xueling , Song Jinling , Wang Ruifen , Zhang Bangwen
Published: February 2021

Bismuth halide oxide with three halogen elements (P‐BiOXs) catalyst was prepared by a facile precipitation method at room temperature only for 30 min. Several measurement technologies were employed to characterise the structures and morphologies of the obtained samples. Coloured Rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and colourless bisphenol A (BPA) were selected to evaluate the photocatalytic activity of the samples. The experimental results showed the P‐BiOXs thin nanoplates exhibited the most excellent photocatalytic activity among the prepared samples for the degradation of MO under visible light illumination. More importantly, the catalyst P‐BiOXs could effectively degradate RhB, MB and BPA. The P‐BiOXs catalyst displayed good photocatalytic stability by the recycling tests. The highly efficient visible light catalytic properties of P‐BiOXs could be due to the high specific surface area, enhanced light‐harvesting ability, the suitable bandgap energy and the lower recombination rate of the photogenerated electrons and holes.
Lipoedema – a growing problem in Spain
Authors: Forner-Cordero Isabel , Forner-Cordero Angeles
Published: February 2021

Lipoedema is a chronic disease frequent in women, that causes an abnormal fat deposition in their lower limbs, with a remarkable disproportion between the upper and lower part of the body, easy bruising and pain. Despite the lack of pathognomonic tests for lipoedema, more and more patients in social networks are claiming they suffer from it, giving the disease more visibility but allowing a lot of fake information about lipoedema. Information for self-care and realistic expectations are important. Depending on the severity, the treatment includes: physical therapies, compression garments, exercise, diet, psychological support and surgical treatment.
Teletherapie: eine zukunftsfähige Variante der Versorgung
Authors: Vielitz Arne
Published: February 2021

Cottrell MA, Russell TG. Telehealth for Musculoskeletal Physiotherapy. Musculoskelet Sci Pract 2020; 48: 102193. doi:10.1016/j.msksp.2020.102193
Placebo-Effekte sind vielschichtig und variieren
Authors: Vielitz Arne
Published: February 2021

Perfitt JS, Plunkett N, Jones S. Placebo Effect in the Management of Chronic Pain. BJA Education 2020; 20: 382–387. doi:10.1016/j.bjae.2020.07.002
Maximierung der Therapieeffekte
Authors: Vielitz Arne
Published: February 2021

Bishop MD, Bialosky JE, Alappattu MJ. Riding a Tiger: Maximizing Effects of Manual Therapies for Pelvic Pain. Journal of Women´s Health Physical Therapy 2020; 44: 32–38. doi:10.1097/JWH.0000000000000156
Pränatale Strahlenexposition aus nuklearmedizinischer Indikation
Authors: Happel Christian , Borowski Markus , Kamp Alexandra , Rudolf Frank , Wicke Jan Henryk , Gröner Daniel , Grünwald Frank , Fiebich Martin
Published: February 2021

Die nuklearmedizinische Strahlenexposition Schwangerer kann bei Patientinnen sowie bei den Behandelnden Unsicherheit hervorrufen. Der 2019 überarbeitete DGMP-Bericht „Pränatale Strahlenexposition aus medizinischer Indikation, Dosisermittlung, Folgerungen für Arzt und Schwangere“ bietet eine Grundlage zur Ermittlung der Dosis für das Ungeborene. Die vorliegende Übersichtsarbeit fasst die wichtigsten allgemeinen Änderungen der neuen Version des Berichts zusammen und stellt die für die Nuklearmedizin wesentlichen Aspekte detailliert vor.

Die rasante Weiterentwicklung des Indikationsspektrums der nuklearmedizinischen und der radiologischen Bildgebung hat den Anlass gegeben, den Bericht im Jahr 2019 komplett zu überarbeiten. Dabei wurde zudem der Erweiterung des Gerätespektrums nuklearmedizinischer Hybridgeräte sowie der Einführung neuer Radiotracer Rechnung getragen. Die Berechnung der Dosis des Ungeborenen erfolgt auf der Basis aktueller Dosiskoeffizienten. Die wichtigste Änderung zur Vorversion des DGMP-Berichts ist die Umwandlung des 3-Stufen-Konzepts der Dosisermittlung in ein 2-Stufen-Konzept. Bei nuklearmedizinischen Untersuchungen erfolgt nun in Stufe 1 eine konservative Abschätzung der Strahlenexposition nach Tabellen auf Basis der diagnostischen Referenzwerte aus dem Jahr 2012. Liegt diese unter 20 mSv, besteht keine Notwendigkeit für weiterführende Maßnahmen, insbesondere besteht keine strahlenbiologische Indikation für einen Schwangerschaftsabbruch. Werden 20 mSv überschritten, liegen für eine Untersuchung keine DRW vor oder für den Fall einer nuklearmedizinischen Therapie ist eine genauere Berechnung nach Stufe 2 des 2-Stufen-Konzepts erforderlich. Diese sieht eine Berechnung der Strahlenexposition unter Berücksichtigung der tatsächlich verabreichten Aktivität und des Schwangerschaftsstadiums vor.

Der DGMP-Bericht zur pränatalen Strahlenexposition ist ein Leitfaden für nuklearmedizinisch tätige Ärzte und Medizinphysik-Experten (MPE). Die enthaltenen Berechnungsgrundlagen und Handlungsempfehlungen sind eine wichtige Grundlage zur Abschätzung der Dosis bei der Strahlenexposition Ungeborener.
Validating the Matching of Patients in the Linkage of a Large Hospital System's EHR with State and National Death Databases
Authors: Conway Rebecca B. N. , Armistead Matthew G. , Denney Michael J. , Smith Gordon S.
Published: February 2021

Background Though electronic health record (EHR) data have been linked to national and state death registries, such linkages have rarely been validated for an entire hospital system's EHR.

Objectives The aim of the study is to validate West Virginia University Medicine's (WVU Medicine) linkage of its EHR to three external death registries: the Social Security Death Masterfile (SSDMF), the national death index (NDI), the West Virginia Department of Health and Human Resources (DHHR).

Methods Probabilistic matching was used to link patients to NDI and deterministic matching for the SSDMF and DHHR vital statistics records (WVDMF). In subanalysis, we used deaths recorded in Epic (n = 30,217) to further validate a subset of deaths captured by the SSDMF, NDI, and WVDMF.

Results Of the deaths captured by the SSDMF, 59.8 and 68.5% were captured by NDI and WVDMF, respectively; for deaths captured by NDI this co-capture rate was 80 and 78%, respectively, for the SSDMF and WVDMF. Kappa statistics were strongest for NDI and WVDMF (61.2%) and NDI and SSDMF (60.6%) and weakest for SSDMF and WVDMF (27.9%). Of deaths recorded in Epic, 84.3, 85.5, and 84.4% were captured by SSDMF, NDI, and WVDMF, respectively. Less than 2% of patients' deaths recorded in Epic were not found in any of the death registries. Finally, approximately 0.2% of “decedents” in any death registry re-emerged in Epic at least 6 months after their death date, a very small percentage and thus further validating the linkages.

Conclusion NDI had greatest validity in capturing deaths in our EHR. As a similar, though slightly less capture and agreement rate in identifying deaths is observed for SSDMF and state vital statistics records, these registries may be reasonable alternatives to NDI for research and quality assurance studies utilizing entire EHRs from large hospital systems. Investigators should also be aware that there will be a very tiny fraction of “dead” patients re-emerging in the EHR.
Respiratory Care in Children with COVID-19
Authors: Gupta Shalu , Angurana Suresh K. , Kumar Virendra
Published: February 2021

The novel coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is causing significant morbidity and mortality worldwide. The common presentations in children include involvement of respiratory system leading to pneumonia and acute respiratory distress syndrome, as well as multiorgan dysfunction syndrome and multisystem inflammatory syndrome in children (MIS-C). Pediatric COVID-19 is a milder disease as compared with the adults. Also, there is rise in MIS-C cases which is a hyperinflammatory condition temporally associated with SARS-CoV-2. Since respiratory system is predominantly involved, few of these critically ill children often require respiratory support which can range from simple oxygen delivery devices, high-flow nasal cannula (HFNC), noninvasive ventilation (NIV), invasive mechanical ventilation, and extracorporeal membrane oxygenation (ECMO). Most of the oxygen delivery devices and respiratory interventions generate aerosols and pose risk of transmission of virus to health care providers (HCPs). The use of HFNC and NIV should be limited to children with mild respiratory distress preferably in negative pressure rooms and with adequate personal protective equipment (PPE). However, there should be low thresholds for intubation and invasive mechanical ventilation in the event of clinical deterioration while on any respiratory support. The principle of providing respiratory support requires special droplet and air-borne precautions to limit exposure or transmission of virus to HCPs and at the same time ensuring safety of the patient.
Feasibility of Same Day Discharge Post-Peroral Endoscopic Myotomy
Authors: DiJoseph Kara , Manzo Carl , Pauli Eric , Mathew Abraham
Published: February 2021

Peroral endoscopic myotomy (POEM) has emerged as a successful treatment for achalasia and other spastic disorders of the esophagus. With clinical experience, a same day discharge protocol has been developed. Readmission rates and postprocedural complications related to POEM procedures at a single institution were compared in patients discharged same day versus overnight observation. A total of 66 patients were discharged within hours after the procedure while 88 were admitted for monitoring overnight; no differences in readmissions or complications were identified. Same day discharge after POEM is relatively safe and has no difference in readmission or complication rates compared with overnight observations.
Creating gallium arsenide photocathodes with high quantum efficiencies
Authors: Larter Raima
Published: February 2021

Method for activating GaAs photocathodes using an initial surface heat-cleaning step.
Quantum computer based on color centers in diamond
Authors: Pezzagna Sébastien , Meijer Jan
Published: February 2021

Artificial atoms like the nitrogen vacancy (NV) centers in diamond enable the realization of fully functional qubits in a solid at room temperature. The functionalities of all the parts needed to create a quantum computer, such as quantum error correction, couplings, quantum teleportation, and a quantum repeater, have already been experimentally demonstrated. These achievements are expected to influence the industrial development of quantum information technology as well as quantum sensing. Whereas quantum sensing has been established and a large number of organizations are working on new developments in this area, a quantum computer itself remains elusive due to technical reasons and limitations of the available materials. For example, only in recent months has it become possible to electrically readout the NV spin state at the level of a single center and significantly improve the scalability of NV center production. A number of ideas have been proposed to overcome the above-mentioned limitations. This paper summarizes the status of research in the area, details the most promising concepts for development, and discusses factors limiting progress as well as the most recent developments in the field.
Effect of film structure on CH3NH3PbI3 perovskite thin films’ degradation
Authors: Khelfaoui F. , Belaidi I. , Attaf N. , Aida M. S.
Published: February 2021

The instability of CH3NH3PbI3 perovskite hybrid organic–inorganic films is a serious problem, which might be a drawback for their use in solar energy conversion. In this work, we have evaluated the degradation of the perovskite films and studied the influence of film morphology on their degradation. CH3NH3PbI3 perovskite thin films were deposited on glass substrates by a spin coating technique at different centrifugation speeds using different solvents. This study aims to determine the films’ properties that may control the degradation process. This study was based on the comparison between the characteristics determined from XRD analysis and optical transmittance of freshly deposited films and those aged 1 year in ambient air at room temperature and dark conditions. The degradation was manifested by the partial decomposition of the perovskite to PbI2, I2, and metallic lead. The degradation evaluation was achieved by the determination of the variation of the most intense XRD diffraction peak in the freshly prepared film and after aging. The results indicated that the degradation is very sensitive to the films’ porosity and thickness. Reducing the thickness of the film or increasing the porosity enhances the degradation process.
Progress and future prospects of negative capacitance electronics: A materials perspective
Authors: Hoffmann Michael , Slesazeck Stefan , Mikolajick Thomas
Published: February 2021

Negative capacitance in ferroelectric materials has been suggested as a solution to reduce the power dissipation of electronics beyond fundamental limits. The discovery of ferroelectricity and negative capacitance in the widely used class of HfO2-based materials has since sparked large research efforts to utilize these effects in ultra-low power transistors. While significant progress has been made in the basic understanding of ferroelectric negative capacitance in recent years, the development of practical devices has seen limited success so far. Here, we present a unique view of the field of negative capacitance electronics from the ferroelectric materials perspective. Starting from the basic principles of ferroelectric negative capacitance, we discuss the desirable characteristics of a negative capacitance material, concluding that HfO2-based ferroelectrics are currently most promising for applications in electronics. However, we emphasize that material non-idealities can complicate and in some cases even inhibit the design and fabrication of practical negative capacitance devices using HfO2-based ferroelectrics. Finally, we review the recent progress on experimental devices and give an outlook on the future direction of the field. In particular, further investigations of the microscopic structure of HfO2-based ferroelectrics are needed to provide an insight into the origin of negative capacitance in this material system and to enable predictive device design.
Effects of breathing cracks on the dynamic characteristics of a drilling riser under irregular waves and the crack identification
Authors: Zhou Xingkun , Sun Yuqing , Li Wenhua
Published: February 2021

To investigate the effects of breathing cracks on the dynamic characteristics, i.e., natural frequencies, vibration displacement, slope angle, and bending moment, of a drilling riser, a time-domain finite element method based on the fracture mechanics theory is developed. The correctness of the proposed method is verified, and the performance of the different dynamic characteristics for crack identification is evaluated. First, the influence of the breathing and open cracks on natural frequencies is explored. The maximum frequency shifts vs crack location and water depth are studied. The results of the small difference of natural frequencies between intact and cracked risers illustrate that the traditional frequency-based crack-detection method is not applicable for the risers. Second, the time-domain motions, orbit plots, Poincaré maps, and fast Fourier transform diagrams are extracted for discussing the effects of the breathing and open cracks and crack depth and location. Finally, the second and fourth derivatives of the root-of-mean-square (RMS) of the dynamic response characteristics are defined for crack identification. It is found that the moment RMS has a good performance in single- and multiple-crack identifications and that not only locations but also degrees of the breathing cracks can be well detected by the proposed indices. In short, several conclusions drawn are a benefit for the safety of a serviced drilling riser system.
Large electrocaloric effect in lead-free ferroelectric Ba0.85Ca0.15Ti0.9Zr0.1O3 thin film heterostructure
Authors: Barman Abhisikta , Chatterjee Subhashree , Ou Canlin , Yau Tse Yau , Banerjee Niladri , Kar-Narayan Sohini , Datta Anuja , Mukherjee Devajyoti
Published: February 2021

A large electrocaloric effect is reported in a strain-engineered Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) thin film heterostructure driven by the near room-temperature electro-structural phase transition. An epitaxial BCZT/La0.7Sr0.3MnO3 (BCZT/LSMO) heterostructure was grown on a single-crystal SrTiO3 (100) substrate using pulsed laser deposition. In-depth x-ray diffraction and x-ray spectroscopic analyses revealed the single-crystalline nature and stoichiometric growth of the heterostructure. Both temperature dependent x-ray diffraction and dielectric measurements revealed a broad second-order-type phase transition near 430 K in the BCZT/LSMO heterostructure. From detailed theoretical analyses of the experimental data, it was confirmed that the phase transition around 430 K is second-order in nature, unlike the first-order transition observed in bulk BCZT materials. Thermodynamic analyses of polarization revealed an unprecedently large adiabatic temperature change of 13.5 K at 430 K under a field change of 1000 kV cm−1, hitherto unobserved in a lead-free material. Extremely broad adiabatic temperature change ΔT(T) curves over a wide working range of temperatures (330 K < T < 480 K) resulted in enhanced relative cooling powers, which are higher than those reported so far in most electrocaloric materials. We propose that an interfacial strain-induced enhanced tetragonal distortion of the BCZT layer gives rise to these large electrocaloric effects in the BCZT/LSMO heterostructure system. The demonstration of a large electrocaloric effect in the lead-free BCZT thin film may open up new pathways toward the design of artificial heterostructures for eco-friendly solid-state cooling applications.
Fabrication of a high-speed plasmonic reflection/transmission modulator
Authors: Siadat Mousavi Saba , Olivieri Anthony , Berini Pierre
Published: February 2021

The fabrication of a high-speed plasmonic reflection/transmission modulator for operation at λ0 = 1550 nm is presented and described in detail. Front-side ground and signal contacts provide easy electrical probe access to the device, while allowing the transmission of light through the substrate. Modulation is based on enhanced perturbation of the effective refractive index of grating-coupled surface plasmon polaritons propagating along a metal–oxide–semiconductor structure on silicon. Fabrication steps include deposition of a plasmonic metal patch, deposition of Ohmic contacts, deposition of an Au nanograting coupler overlaid by e-beam lithography, and the application of an intermetal dielectric layer with metalized vias and metal electrical contacts. Current–voltage and capacitance–voltage characteristics verify the electrical integrity of the structure.
Wildlife and conservation biology.
Authors: Rees Paul A.
Published: February 2021

This chapter contains questions about wildlife management and conservation, endangered species, nature reserve design and the role of zoos in conservation. The questions are arranged by topic and divided into three levels: foundation, intermediate and advanced.
Urban ecology and waste management.
Authors: Rees Paul A.
Published: February 2021

This chapter contains questions about the structure and functioning of urban ecosystems and the management of the waste they produce. The questions are arranged by topic and divided into three levels: foundation, intermediate and advanced.
Environmental and wildlife law and policy.
Authors: Rees Paul A.
Published: February 2021

This chapter contains questions about the laws and policies that protect wildlife and the environment. The questions are arranged by topic and divided into three levels: foundation, intermediate and advanced.
Processing visual information in elite junior soccer players: Effects of chronological age and training experience on visual perception, attention, and decision making
Authors: Klatt Stefanie , Smeeton Nicholas J.
Published: February 2021

Processing information in peripheral vision is an important perceptual‐cognitive skill in team sports. The relative contribution of various perceptual‐cognitive skills to expertise in sports throughout adolescence has not been investigated in detail yet. The current study examined the effects of chronological age and training experience on perception, attention, and decision making in young soccer players. Sixty‐five elite youth players were required to judge different game situations in a decision‐making task involving both perceptual (object detection) and attentional (postural feature recognition) skills to perceive player configurations in the visual periphery. In general, performance decreased in the decision‐making and feature‐recognition tasks with increasing use of peripheral visual field, but not in the object‐detection task. Superior performances were found for under 18‐years‐old players compared to under 16‐years‐old players especially in their attentional skills. Higher training experience affected decision‐making and attentional performance. Overall, the findings provide insights and implications for training perceptual‐cognitive skills in team sports

Highlights

Elite youth soccer players' performance decreased in a soccer‐specific decision‐making and feature‐recognition tasks with increasing use of peripheral visual field, but not in an object‐detection task.

Superior performances were found for under 18 years old players compared to under 16 years old players especially in their attentional skills.

Both chronological age and training experience influenced the recognition of postural feature in peripheral vision, whereas player detection was unaffected.

The ability to recognize postural features in peripheral vision is an important characteristic of decision making in sports and requires a mature visual system, sufficient attentional capacity, and may be developed through extended task‐specific practice.
Extracellular matrix biomimetic polymeric membranes enriched with silver nanoparticles for wound healing
Authors: Stefan Laura Mihaela , Iosageanu Andreea , Ilie Daniela , Stanciuc Ana-Maria , Matei Cristian , Berger Daniela , Craciunescu Oana
Published: February 2021

Severe skin injuries, including burns, represent a real concern for the global health-care system and therefore, there is an increased interest in developing wound dressings, in order to stimulate and enhance skin tissue repair. The aim of this study was to design novel hybrid materials, biomimetic to skin extracellular matrix and enriched with silver nanoparticles (nAg), in order to provide both dermal tissue regeneration and antimicrobial activity. Two material variants (variant A and variant B) consisting of type I collagen (COL), chondroitin sulfate (CS) and k-elastin peptides (EL) enriched with positively-charged nAg, were conditioned as membranes. UV exposure ensured both sterilisation and cross-linking of the materials. Physico-chemical characterization of the hybrid biomaterials showed values of density and swelling degree higher than those of COL membrane, while the process of in vitro degradation followed a similar pattern. Infrared spectroscopy and x-ray diffraction indicated alterations of the characteristic structural features and crystallinity of COL after blending with CS and EL and nAg embedding. Scanning electron microscopy observations revealed different surface morphologies of the hybrid membranes, according to their composition. In vitro studies on L929 fibroblasts and HaCaT keratinocytes showed that both hybrid membranes exhibited good cytocompatibility and promoted higher cell proliferation compared to COL sample, as evaluated by MTT and Live/Dead assays. The presence of actin filaments highlighted by fluorescent labelling confirmed the fibroblast and keratinocyte adhesion onto the surface of hybrid membranes. Most importantly, both materials showed an increased wound healing ability in an in vitro scratch assay model, stimulating cell migration at 24 h post-seeding. In addition, good antimicrobial activity was recorded, especially against Gram-positive bacterial strain. Altogether, our findings recommend COL-CS-EL-nAg hybrid membranes as good candidates for wound healing acceleration and bioengineering of skin tissue.
A century of change
Authors: Curtis Susan
Published: February 2021

The Institute of Physics was created in 1920 to champion a new generation of professional physicists working in industry, academia and the government, as Susan Curtis describes
Embracing a life of variables
Authors: Commissariat Tushna
Published: February 2021

Steve Bullock is an engineer, physics teacher, science communicator and education consultant. Currently the programme director of undergraduate aerospace engineering at the University of Bristol, UK, he talks to Tushna Commissariat about a career of bold choices, sideways jumps and obstacles overcome
Therapeutic Potential of a Self-Assembling Peptide Hydrogel to Treat Colonic Injuries Associated with Inflammatory Bowel Disease
Authors: Araki Toshihiro , Mitsuyama Keiichi , Yamasaki Hiroshi , Morita Masaru , Tsuruta Kozo , Mori Atsushi , Yoshimura Tetsuhiro , Fukunaga Shuhei , Kuwaki Kotaro , Yoshioka Shinichiro , Takedatsu Hidetoshi , Kakuma Tatsuyuki , Akiba Jun , Torimura Takuji
Published: February 2021

Background and Aims

The Self-assembling Peptide Hydrogel [SAPH, PuraMatrix], a fully synthetic peptide solution designed to replace collagen, has recently been used to promote mucosal regeneration in iatrogenic ulcers following endoscopic submucosal dissection. Herein, we evaluated its utility in ulcer repair using a rat model of topical trinitrobenzene sulphonic acid [TNBS]-induced colonic injuries.

Methods

Colonic injuries were generated in 7-week-old rats by injecting an ethanol solution [35%, 0.2 mL] containing 0.15 M TNBS into the colonic lumen. At 2 and 4 days post-injury, the rats were subjected to endoscopy, and SAPH [or vehicle] was topically applied to the ulcerative lesion. Time-of-flight secondary ion mass spectrometry [TOF-SIMS] was used to detect SAPH. Colonic expression of cytokines and wound healing-related factors were assessed using real-time polymerase chain reaction or immunohistochemistry.

Results

SAPH treatment significantly reduced ulcer length [p = 0.0014] and area [p = 0.045], while decreasing colonic weight [p = 0.0375] and histological score [p = 0.0005] 7 days after injury. SAPH treatment also decreased colonic expression of interleukin [IL]-1α [p = 0.0233] and IL-6[p = 0.0343] and increased that of claudin-1 [p = 0.0486] and villin [p = 0.0183], and β-catenin staining [p = 0.0237]. TOF-SIMS revealed lesional retention of SAPH on day 7 post-injury. Furthermore, SAPH significantly promoted healing in in vivo mechanical intestinal wound models.

Conclusions

SAPH application effectively suppressed colonic injury, downregulated inflammatory cytokine expression, and upregulated wound healing-related factor expression in the rat model; thus, it may represent a promising therapeutic strategy for IBD-related colonic ulcers.
Diverse phenotypic expression associated with the same genetic variant in female heterozygote patients of Anderson–Fabry disease: a case series
Authors: Tomioka Daisuke , Kato Koichi , Ozawa Tomoya , Kodama Kenji , Takahashi Hiroaki , Dochi Kenichi , Ueno Yoshiki , Nakagawa Yoshihisa
Published: February 2021

Background

Anderson–Fabry disease (AFD) is an X-linked lysosomal storage disorder resulting from a mutation of alpha-galactosidase A gene (GLA), causing deficiency in alpha-galactosidase activity. The enzyme deficit can lead to storage of globotriaosylceramide in various organs including heart. Studies suggest that vasospastic angina (VSA) is associated with AFD.

Case summary

This clinical case series aimed to present two female patients with AFD, including progressive cardiac involvement: a 50-year-old woman (patient number 1) and a 39-year-old woman (patient number 2) who are siblings with a male AFD patient harbouring p. Arg342Glu missense variant in alpha-galactosidase A gene (GLA), who suffered VSA and subsequent ventricular fibrillation. Enzymatic tests and genetic analysis confirmed AFD in both female patients and histological tests revealed globotriaosylceramide deposits in their hearts. In patient number 1, a 12-lead electrocardiography and transthoracic echocardiography revealed cardiac hypertrophy. Coronary angiography revealed no organic coronary artery stenosis and vasospasms was induced by spasm provocation test. In patient number 2, no signs of cardiac hypertrophy were found, and coronary arteries had no organic stenosis with negative spasm provocation test. Both patients received enalapril therapy and enzyme replacement therapy (ERT).

Discussion

Different phenotype of AFD was occurred even with the same genetic variant in female heterozygote patients. The duration of exposing accumulation of Gb3 might affect cardiac hypertrophy and vasospasms. Coronary angiography with acetylcholine provocation test should be considered in female AFD patient, especially in case with cardiac hypertrophy.
Utility of coherent and ripple mapping for post-mitral valve plasty biatrial macro-re-entrant tachycardia: a case report
Authors: Sagawa Yuichiro , Yamauchi Yasuteru , Okishige Kaoru , Sasano Tetsuo
Published: February 2021

Background 

Biatrial tachycardia (BiAT) is a rare form of atrial macro-re-entrant tachycardia. Precise identification of interatrial connections and circuits of the BiAT is difficult. And incomplete understanding of the re-entrant circuit may lead to unnecessary ablation, thus increasing the risk of complications.

Case summary 

A 69-year-old man with a history of mitral valve plasty for mitral regurgitation due to mitral valve prolapse was admitted for persistent atrial tachycardia. Electrophysiological examination using the CARTO mapping system was performed. A coherent map revealed an atrial tachycardia with a cycle length of 304 ms and a re-entrant circuit involving the left atrial septum and right atrial septum, while a ripple map suggested an epicardial interatrial connection between the right atrium and left atrium. Radiofrequency ablation on the epicardial connection successfully terminated BiAT without complications.

Discussion 

In BiAT using both atrial septum as a re-entrant circuit, an interatrial connection or an atrial septum can be the target site for ablation. However, septal ablation can be challenging because of the risk of atrioventricular block or interatrial conduction delay, and minimal line or point ablation is needed. Coherent and ripple mapping can accurately determine the re-entrant circuit and interatrial connection of BiAT and reduce complication risks by terminating the atrial tachycardia with minimal ablation.
Case report of an acute myocardial infarction after high-dose recreational nitrous oxide use: a consequence of hyperhomocysteinaemia?
Authors: Oomens Thomas , Riezebos Robert K , Amoroso Giovanni , Kuipers Remko S
Published: February 2021

Background

Nitrous oxide (N2O, laughing gas) is increasingly used as a recreational drug and is presumed relatively safe and innocent. It is often being used in combination with other substances, such as cannabis.

Case summary

A young adult attended the emergency room because of chest pain after recreational use of very high-dose nitrous oxide in combination with cannabis. Electrocardiography demonstrated ST-elevation in the anterior leads. Coronary angiography showed thrombus in the proximal and thrombotic occlusion of the distal left anterior descending coronary artery for which primary percutaneous coronary intervention was attempted. Thrombus aspiration was unsuccessful and the patient was further treated with a glycoprotein IIb/IIIa in addition to dual platelet therapy. Blood results showed low vitamin B12 and folic acid status with concomitant hyperhomocysteinaemia, a known cause of hypercoagulation. Transthoracic echocardiogram showed a moderately reduced left ventricular ejection fraction (LVEF). Three months later, an improvement in LVEF and no recurrent angina or symptoms of heart failure were noticed.

Discussion

We report a case of acute myocardial infarction secondary to very high-dose nitrous oxide abuse in combination with cannabis and possible hypoxia. We propose that severe hyperhomocysteinaemia secondary to nitrous oxide-induced vitamin B12 deficiency together with the vasoconstrictive effects of cannabis might pose a seriously increased risk for intracoronary, among others, thrombus formation. In conclusion, we contest the safety and innocence of recreational nitrous oxide (ab)use, notably in the context of other factors increasing the risk of coagulation.