bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmentally Friendly and Recyclable CuCl2-Mediated C–S Bond Coupling Strategy Using DMEDA as Ligand, Base, and Solvent
Authors: Shen Guodong , Huang Xianqiang , Lu Qichao , Wang Zeyou , Sun Weiwei , Zhang Yalin , Sun Manman , Wang Zhiming
Published: July 2021

Simple reaction conditions and recyclable reagents are crucial for environmentally friendly industrial applications. An environment-friendly, recyclable and economic strategy was developed to synthesize diaryl chalcogenides by the CuCl2-catalyzed C–S bond-formation reaction via iodobenzenes and benzenethiols/1,2-diphenyldisulfanes using N,N′-dimethylethane-1,2-diamine (DMEDA) as ligand, base, and solvent. For these reactions, especially the reactions of diiodobenzenes and aminobenzenethiols/disulfanediyldianilines, a range of substrates are compatible and give the corresponding products in good to excellent yields. Both of the reagents in the catalytic system (CuCl2/DMEDA) are inexpensive, conveniently separable, and recyclable for more than five cycles.
Diastereoselective Palladium-Catalyzed [4+1] Cycloadditions of 4-Vinyl-1,4-dihydro-2H-3,1-benzoxazin-2-ones with In Situ Formed Carbenes
Authors: Ma Yan-Hua , Meng Fan-Xiao , Du Ji-Yuan , Wang Ruo-Nan , Fan Ya-Xin , Su Qing-Qiang
Published: July 2021

Herein, we present a palladium-catalyzed tandem [4+1] cyclo­addition of 4-vinyl-1,4-dihydro-2H-3,1-benzoxazin-2-ones with ­N-tosyl­hydrazones. The reaction is accomplished by merging the in situ generated aza-ortho-quinone methides (aza-o-QMs) with nucleophilic carbenes. This method enables the construction of diverse indolines with broad functional group compatibility in good yields with high levels of diastereoselectivity under mild conditions.
Development of a Chiral N-Alkoxyamide Strategy and Application to the Asymmetric Total Synthesis of Fasicularin
Authors: Sato Takaaki , Minamikawa Ryo , Fukaya Keisuke , Kobayashi Akihiro , Komiya Yukinori , Yamamoto Shio , Urabe Daisuke , Chida Noritaka
Published: July 2021

The asymmetric total synthesis of fasicularin by a chiral N-alkoxyamide strategy is reported. Incorporation of the chiral alkoxy group onto an amide nitrogen changes the original reactivity of the amide, enabling two key transformations: aza-spirocyclization and the reductive Strecker reaction. DFT calculations indicate that pyramidalization of the N-alkoxyamide nitrogen is crucial to produce a cyclic hemiaminal in equilibrium, which undergoes aza-spirocyclization. The chiral alkoxy group is also used as a stereocontrol element to establish two consecutive stereocenters. The iridium-catalyzed reductive Strecker reaction of the N-alkoxylactam provides the aminonitrile with high diastereoselectivity.
Postcardiotomy Extracorporeal Membrane Oxygenation in Neonates
Authors: Yu Xindi , Yang Yinyu , Zhang Wei , Guo Zheng , Shen Jia , Xu Zhuoming , Zhang Haibo , Wang Wei
Published: July 2021

Background Extracorporeal membrane oxygenation (ECMO) provides circulatory support in children with congenital heart disease, particularly in the setting of cardiopulmonary failure and inability to wean from cardiopulmonary bypass. This study summarized the clinical application of ECMO in the treatment of heart failure after cardiac surgery in neonates.

Materials and Methods Clinical data of 23 neonates who received ECMO support in our center from January 2017 to June 2019 were retrospectively analyzed.

Results Twenty-three neonates, aged from 0 to 25 days and weight between 2,300 and 4,500 g, with heart failure postcardiotomy were supported with ECMO. The successful weaning rate was 78.26% and discharge rate was 52.17%. Bleeding and residual malformation were the most common complications. The univariate analysis showed that nonsurvivors were related to the factors such as higher lactate value of ECMO 12 and 24 hours (p = 0.008 and 0.001, respectively), longer time to lactate normalization (p = 0.001), lactate > 10 mmol/L before ECMO (p = 0.01), lower weight (p = 0.01), longer ECMO duration (p = 0.005), lower platelet count (p = 0.001), more surgical site bleeding (p = 0.001), and surgical residual malformation (p = 0.04). Further logistic regression analysis revealed that higher lactate value of ECMO 24 hours (p = 0.003), longer ECMO duration (p = 0.015), and surgical site bleeding (p = 0.025) were independent risk factors.

Conclusion ECMO was an effective technology to support the neonates with cardiopulmonary failure after open heart surgery. Control the lactate acidosis and surgical site bleeding event may be helpful for patients' recovery.
The Association between Ovarian Hyperstimulation Syndrome and Pregnancy Complications following Fertility Treatments
Authors: Vainer-Rotbart Shirah , Sheiner Eyal , Harlev Avi , Bar Guy , Levy Amalia
Published: July 2021

Objective This study was aimed to assess the association between ovarian hyperstimulation syndrome (OHSS) and pregnancy complications among women who conceived following fertility treatment.

Study Design A retrospective population-based cohort study, including all singleton deliveries of patients conceived following ovulation induction (OI) or in vitro fertilization (IVF) between 1988 and 2016, was conducted. All births occurred in a single tertiary medical center. A comparison was performed between deliveries of women who had experienced OHSS at early gestation and subsequently had a pregnancy and women without OHSS. Women lacking prenatal care, multiple gestations, and stillbirths were excluded from the analyses. A multivariable logistic regression model was used to control for confounders.

Results During the study period, 351,373 deliveries met the inclusion criteria, of which 6,748 were deliveries of infants who were conceived by either IVF or OI. Of this study population, 105 cases (1.6%) composed the exposed group, that is, women who had experienced OHSS with a subsequent live birth. In the multivariate analyses, after controlling for confounders, OHSS was not found as an independent risk factor for preeclampsia, gestational diabetes mellitus (GDM), intrauterine growth restriction (IUGR), preterm delivery (both <37 and <34 weeks), low birth weight (LBW), very LBW (VLBW), small for gestational age (SGA), and caesarean delivery. In a subanalysis conducted solely on the IVF population, similar results were found, aside from the association between OHSS and preterm delivery before 34 weeks of gestation which was statistically significant (adjusted odds ratio [AOR] = 2.3 95% confidence interval [CI]: 1.0–5.3, p = 0.049).

Conclusion In our population, OHSS was not found as a risk factor for adverse pregnancy and perinatal outcome. In IVF patients, OHSS is a risk factor for preterm delivery before 34 weeks of gestation.

Key Points
Head Circumference within the Normal Range and Neurodevelopmental Outcomes in Preterm Infants
Authors: Bushman Elisa T. , Blanchard Christina , Sinkey Rachael G. , Harris Stacy , Casey Brian , Tita Alan T. , Ramani Manimaran , Harper Lorie M.
Published: July 2021

Objective We sought to determine if variation in head circumference (HC) within the range of normal (5th–10th and 90th–95th percentile) is associated with poor neurodevelopmental outcomes (NDO), which defined as mild or moderate delay by Bayley II psychometrics (BSID-II).

Study Design This is a secondary analysis of a randomized controlled trial assessing the benefits of magnesium for the prevention of cerebral palsy. Fetuses with a normal HC at birth defined as within 5th to 95th percentile were included. NDO were assessed at age 2 with BSID-II. Moderate delay was defined as a score <70 and mild delay as <85. HC was classified as small normal (5th–10th percentile), normal (10th–90th percentile), and large normal (90th–95th percentile). Logistic regression models adjusted for confounding. Linear regression models estimated the impact for every 1 cm of change in HC.

Results Of 1,236 included infants, 111 (8%) had small normal HC; 1,058 (85%) had normal HC; and 67 (5%) had large normal HC. Baseline characteristics were similar between groups. There was no association with changes in HC within the range of normal and developmental indices. When considered as a continuous variable, every 1 cm increase in HC was also not associated with a significant change in developmental indices.

Conclusion Within the normal range (5th–95th percentile), changes in HC did not correlate with changes in NDO at 2 years as measured by Bayley II scales.

Key Points
Cardiovascular Phenotypic Spectrum of 1p36 Deletion Syndrome
Authors: Kaur Tripat , Sriram Chenni S. , Prasanna Priyanka , Kohli Utkarsh
Published: July 2021

Chromosome 1p36 deletion syndrome is a common genetic anomaly (prevalence: 1 in 5,000–1 in 10,000). Despite reports of cardiovascular involvement, the cardiovascular phenotypic spectrum of patients with 1p36 deletion syndrome is not well characterized. In this article, we reported the clinical course of a full-term African American boy with chromosome 1p36 deletion syndrome and neonatal onset of severe cardiac disease with moderate-to-severe biventricular dysfunction and severe pulmonary hypertension. Early neonatal onset presentation of 1p36 deletion syndrome is rare and might be associated with a more guarded prognosis. This case based study is supplemented by a comprehensive review of cardiovascular involvement in this relatively common genetic syndrome.
Feminist digital diplomacy and foreign policy change in Sweden
Authors: Aggestam Karin , Rosamond Annika Bergman , Hedling Elsa
Published: July 2021

This article analyses how the launch of Sweden’s feminist foreign policy marked a change in Sweden’s digital diplomatic efforts. It draws on three strands of research: digital diplomacy, foreign policy analysis (FPA) and feminist scholarship. Informed by FPA, the article explores the relevance of political leadership, bureaucratic agency and political context as drivers of policy change, and, specifically, Sweden’s feminist digital diplomacy. The article provides an empirical case analysis of Sweden’s foreign policy change and conduct of digital diplomacy during the period 2006–2020. It draws on documents available on the official websites of the Government Offices of Sweden and the Ministry for Foreign Affairs, including sites such as SwedenAbroad and Swedish Foreign Policy Stories. The article concludes that Sweden acted on a window of opportunity in global politics, which advanced a novel feminist digital diplomacy. Sweden’s competitive edge was based on a strong transformative political leadership in foreign policy, state feminism and an early engagement of digital diplomatic management of its state image online.
Gram-negative outer-membrane proteins with multiple β-barrel domains
Authors: Solan Ron , Pereira Joana , Lupas Andrei N. , Kolodny Rachel , Ben-Tal Nir
Published: July 2021

Significance

All currently known architectures of outer-membrane beta barrels (OMBBs) have only one barrel. While the vast majority function as oligomers, with barrels from different chains packing against each other in the membrane, it was assumed that these multiple chains are needed to form multibarrel structures. And yet, here we show that multibarrel chains exist. Using state-of-the-art sequence and structure analysis tools, we report the discovery of more than 30 multibarrel architectures from gram-negative bacteria. The discovery of these architectures reveals another interesting chapter in OMBB evolution and has implications for protein engineering. The evolutionary advantages of multibarrels are yet to be discovered.
On the etymology of the Japanese plural suffix and its possible connection to Korean
Authors: Francis-Ratte Alexander
Published: July 2021

This paper presents an etymological analysis of the Japanese plural suffix tachi, Old Japanese tati. I propose that tati originates from a grammaticalization of an earlier Pre-Old Japanese phonological form *totwi, the non-bound reflex of which is the Old Japanese quasi-collective marker dwoti ‘fellow (person), everyone, together’. The reconstruction of a Pre-Old Japanese stem *totwi (Pre-Proto-Japanese /*tətəj/) with quasi-collective and plural function clarifies the possible connection of the Japanese plural suffix to the Korean plural suffix tul (Middle Korean tólh), which Whitman (1985, p. 217) proposed to be cognates but which has since been criticized on phonological and distributional grounds. I show that reconstructing the earliest form of the Japanese plural suffix as /*tətəj/ resolves each of the three phonological issues with the Japano-Koreanic comparison, creates a better morphosyntactic match between the two languages, and rules out a loanword relationship of the Japanese and Korean forms.
Farm 4.0: innovative smart dairy technologies and their applications as tools for welfare assessment in dairy cattle
Authors: Azarpajouh S. , Calderón Díaz J.A. , Bueso Quan S. , Taheri H.
Published: July 2021

The growing world population has increased the demand for meat and milk products and has led to a rapid growth in the scale of cattle enterprises globally. As a result, livestock production would intensify even more with farmers aiming to maximize output per animal unit and it would lower the stockperson per animal ratio. This will result in less time available to monitor and manage individual animals properly, jeopardizing animal health and welfare. The recent advancement in technological and engineering tools and materials such as advanced sensors and sensing devices, and data processing and machine learning methods provide effective tools for the dairy industry to control qualitative and quantitative parameters related to dairy cattle health and welfare. This review paper will (a) explain smart dairy technologies, (b) describe on-farm cattle welfare assessment, and (c) discuss sensors applied in automatic cattle welfare assessment.
‘Schoolies Week’ on the Gold Coast, Australia
Authors: Pathirana Madura , Scott Noel
Published: July 2021

‘Schoolies Week’ on the Gold Coast, Australia, is an annual celebration by students completing high school. These 17–18-year-olds want to celebrate their freedom and the completion of an important stage of their lives. For some students this may be their first time away from home with their friends. For most students it is a time of celebration, but they are sometimes criticized for drinking alcohol, taking drugs, indulging in underage sex and high-spirits partying. This may cause problems for residents and other tourists. The newspaper coverage of Schoolies Week is mostly negative and detracts from the destination’s image. After some years grappling with Schoolies Week, the Queensland State Government intervened to provide a safe environment for these celebrations. They created several ‘diversionary’ events to provide activities for ‘schoolies’, and there is a large police presence as well as many volunteers to support those who are drugged or drunk. How do
you
think Schoolies Week should be managed?

Information

© CAB International 2021
Maggie Breaks into Tanzania’s Male-Dominated World of Wildlife Tourism
Authors: Duval Justine , Lods Aurélie , Quemener Margot , Vindolet Camille , Zhu Chuhong
Published: July 2021

Maggie’s Tour Company Limited is a small enterprise located in Arusha (Tanzania) owned and managed by Maggie Duncan Simbeye, the first Tanzanian woman to own and operate her own tour company. She manages her business with a masterful hand, driven by a strong belief in the importance of respecting and protecting the environment, offering ‘responsible travel to natural areas that conserves the environment and improves the well-being of local people’.

Information

For Skema: Written on the basis of material provided by Maggie Simbeye of Maggie’s Tour Company.

© CAB International 2021
Mitochondrial regulation of ferroptosis
Authors: Gan Boyi
Published: July 2021

Ferroptosis is a form of iron-dependent regulated cell death driven by uncontrolled lipid peroxidation. Mitochondria are double-membrane organelles that have essential roles in energy production, cellular metabolism, and cell death regulation. However, their role in ferroptosis has been unclear and somewhat controversial. In this Perspective, I summarize the diverse metabolic processes in mitochondria that actively drive ferroptosis, discuss recently discovered mitochondria-localized defense systems that detoxify mitochondrial lipid peroxides and protect against ferroptosis, present new evidence for the roles of mitochondria in regulating ferroptosis, and outline outstanding questions on this fascinating topic for future investigations. An in-depth understanding of mitochondria functions in ferroptosis will have important implications for both fundamental cell biology and disease treatment.
Effect of auxiliary gas injection on the operation of a Hall current plasma accelerator
Authors: Karadag Burak
Published: July 2021

Optimization of magnetic and electric fields has been central concern for the design of a Hall current plasma accelerator since its inception decades ago. However, neutral flow dynamics in the discharge channel may have as much impact on the accelerator performance, operation stability and lifetime as the magnetic and electric fields due to its strong coupling with plasma properties. In this article, auxiliary gas injection is numerically studied for a low-power accelerator using a two-dimensional fully kinetic particle-in-cell code. Gas injection through the discharge channel sidewalls increases lifetime of the accelerator, but also degrades thrust performance suggesting that there is an optimum gas injection ratio. Although reduction in the maximum erosion rate is substantially lower than that predicted by a two-dimensional hybrid model for a high-power accelerator [14], extension of lifetime by approximately 20% appears to be possible with little impact (2%) on the thrust. The anode efficiency analysis supported by the simulated plasma properties clarifies that reduction in voltage utilization is the main cause of the observed alterations in the plasma properties and thrust performance deterioration.
Detecting and classifying neurotransmitter signals from ultra-high sensitivity PET data: the future of molecular brain imaging
Authors: Liu Heather , Morris Evan D
Published: July 2021

Efforts to build the next generation of brain PET scanners are underway. It is expected that a new scanner (NS) will offer an order-of-magnitude improvement in sensitivity to counts compared to the current state-of-the-art, Siemens HRRT. Our goal was to explore the use of the anticipated increased sensitivity in combination with the linear-parametric neurotransmitter PET (lp-ntPET) model to improve detection and classification of transient dopamine (DA) signals. We simulated striatal [11C]raclopride PET data to be acquired on a future NS which will offer ten times the sensitivity of the HRRT. The simulated PET curves included the effects of DA signals that varied in start-times, peak-times, and amplitudes. We assessed the detection sensitivity of lp-ntPET to various shapes of DA signal. We evaluated classification thresholds for their ability to separate ‘early’- versus ‘late’-peaking, and ‘low’- versus ‘high’-amplitude events in a 4D phantom. To further refine the characterization of DA signals, we developed a weighted k-nearest neighbors (wkNN) algorithm to incorporate information from the neighborhood around each voxel to reclassify it, with a level of certainty. Our findings indicate that the NS would expand the range of detectable neurotransmitter events to 72%, compared to the HRRT (31%). Application of wkNN augmented the detection sensitivity to DA signals in simulated NS data to 92%. This work demonstrates that the ultra-high sensitivity expected from a new generation of brain PET scanner, combined with a novel classification algorithm, will make it possible to accurately detect and classify short-lived DA signals in the brain based on their amplitude and timing.
Instantaneous frequency measurement using two parallel I/Q modulators based on optical power monitoring
Authors: Wang Chuangye , Ning Tigang , Li Jing , Pei Li , Zheng Jingjing , Zhang Jingchuan
Published: July 2021

A scheme for instantaneous frequency measurement (IFM) using two parallel I/Q modulators based on optical power monitoring is proposed. The amplitude comparison function (ACF) can be constructed to establish the relationship between the frequency of radio frequency (RF) signal and the power ratio of two optical signals output by two I/Q modulators. The frequency of RF signal can be derived by measuring the optical power of the optical signals output by two I/Q modulators. The measurement range and measurement error can be adjusted by controlling the delay amount of the electrical delay line. The feasibility of the scheme is verified, and the corresponding measurement range and measurement error of the system under different delay amounts of the electrical delay line are given. Compared with previous IFM schemes, the structure of this scheme is simple. Polarization devices, a photodetector and an electrical power meter are not used, which reduces the impact of the environmental disturbance on the system and the cost of the system. In simulation, the measurement range can reach 0 GHz–24.5 GHz by adjusting the delay amount of the electrical delay line τ = 20 ps. The measurement error of the scheme is better at low frequency, and the measurement error of low frequency 0 GHz–9.6 GHz can reach –0.1 GHz to +0.05 GHz.
Electronic and optical properties of 3N-doped graphdiyne/MoS2 heterostructures tuned by biaxial strain and external electric field*
Authors: Wei Dong , Li Yi , Feng Zhen , Guo Gaofu , Ma Yaqiang , Yu Heng , Luo Qingqing , Tang Yanan , Dai Xianqi
Published: July 2021

The construction of van der Waals (vdW) heterostructures by stacking different two-dimensional layered materials have been recognised as an effective strategy to obtain the desired properties. The 3N-doped graphdiyne (N-GY) has been successfully synthesized in the laboratory. It could be assembled into a supercapacitor and can be used for tensile energy storage. However, the flat band and wide forbidden bands could hinder its application of N-GY layer in optoelectronic and nanoelectronic devices. In order to extend the application of N-GY layer in electronic devices, MoS2 was selected to construct an N-GY/MoS2 heterostructure due to its good electronic and optical properties. The N-GY/MoS2 heterostructure has an optical absorption range from the visible to ultraviolet with a absorption coefficient of 105 cm−1. The N-GY/MoS2 heterostructure exhibits a type-II band alignment allows the electron-hole to be located on N-GY and MoS2 respectively, which can further reduce the electron-hole complexation to increase exciton lifetime. The power conversion efficiency of N-GY/MoS2 heterostructure is up to 17.77%, indicating it is a promising candidate material for solar cells. In addition, the external electric field and biaxial strain could effectively tune the electronic structure. Our results provide a theoretical support for the design and application of N-GY/MoS2 vdW heterostructures in semiconductor sensors and photovoltaic devices.
Photonic spin Hall effect and terahertz gas sensor via InSb-supported long-range surface plasmon resonance
Authors: Cheng Jie , Wang Gaojun , Dong Peng , Liu Dapeng , Chi Fengfeng , Liu Shengli
Published: July 2021

The photonic spin Hall effect (SHE), featured by a spin-dependent transverse shift of left- and right-handed circularly polarized light, holds great potential for applications in optical sensors, precise metrology and nanophotonic devices. In this paper, we present the significant enhancement of photonic SHE in the terahertz range by considering the InSb-supported long-range surface plasmon resonance (LRSPR) effect. The influences of the InSb/ENZ layer thickness and temperature on the photonic SHE were investigated. With the optimal structural parameters and temperature, the maximal spin shift of the horizontal polarization light can reach up to 2.68 mm. Moreover, the spin shift is very sensitive to the refractive index change of gas, and thus a terahertz gas sensing device with a superior intensity sensitivity of 2.5 × 105 μm/RIU is proposed. These findings provide an effective method to enhance the photonic SHE in the terahertz range and therefore offer the opportunity for developing the terahertz optical sensors based on photonic SHE.
The 266-nm ultraviolet-beam generation of all-fiberized super-large-mode-area narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate
Authors: Li Shun , Li Ping-Xue , Yang Min , Yu Ke-Xin , Zhu Yun-Chen , Dong Xue-Yan , Yao Chuan-Fei
Published: July 2021

We report on a compact, stable, all-fiberized narrow-linewidth (0.045 nm) pulsed laser source emitting laser beam with a wavelength of 266 nm, and tunable pulse width and repetition rate. The system is based on all-fiberized nanosecond amplifier architecture, which consists of Yb-doped fiber preamplifiers and a super-large-mode-area Yb-doped fiber power amplifier. The fiber amplifier with a core of 50 μm is used to raise the threshold of the stimulated Brillouin scattering (SBS) effect and to obtain high output power and single pulse energy. Using lithium triborate (LBO) crystal and beta-barium borate (BBO) crystal for realizing the second-harmonic generation (SHG) and fourth-harmonic generation (FHG), we achieve 17 μJ (1.73 W) and 0.66 μJ (66 mW), respectively, at wavelengths of 532 nm and 266 nm and a repetition rate of 100 kHz with pulse width of 4 ns. This source has great potential applications in fluorescence research and solar-blind ultraviolet optical communication.
Magnetoresistance effect in vertical NiFe/graphene/NiFe junctions
Authors: Li Pei-Sen , Peng Jun-Ping , Hu Yue-Guo , Guo Yan-Rui , Qiu Wei-Cheng , Wu Rui-Nan , Pan Meng-Chun , Hu Jia-Fei , Chen Di-Xiang , Zhang Qi
Published: July 2021

For convenient and efficient verification of the magnetoresistance effect in graphene spintronic devices, vertical magnetic junctions with monolayer graphene sandwiched between two NiFe electrodes are fabricated by a relatively simple way of transferring CVD graphene onto the bottom ferromagnetic stripes. The anisotropic magnetoresistance contribution is excluded by the experimental result of magnetoresistance (MR) ratio dependence on the magnetic field direction. The spin-dependent transport measurement reveals two distinct resistance states switching under an in-plane sweeping magnetic field. A magnetoresistance ratio of about 0.17 % is obtained at room temperature and it shows a typical monotonic downward trend with the bias current increasing. This bias dependence of MR further verifies that the spin transport signal in our device is not from the anisotropic magnetoresistance. Meanwhile, the I–V curve is found to manifest a linear behavior, which demonstrates the Ohmic contacts at the interface and the metallic transport characteristic of vertical graphene junction.
Multi-frequency focusing of microjets generated by polygonal prisms
Authors: Yang Yu-Jing , Zhang De-Long , Hua Ping-Rang
Published: July 2021

We systematically investigate the power distribution characteristics of microjets generated by prismatic scatterers with different shapes at sub-THz region (λ = 8.57 mm). Among these prismatic scatterers, the hexagonal-type one shows better focusing feature than the others. Aiming at the hexagonal-type one, we propose a double-layer scatterer composed of a Teflon hexagonal prism as an outer layer and a semiconductor cuboid as an inner layer. Aiming at the double-layer scatterer, we further study the effects of refractive index, size, and shape of the inner cuboid on microjet’s features. The study allows us to present an optimized double-layer scatterer, which has a side length λ/2 (λ) and a refractive index 2.0 (1.4) for the inner (outer) layer. We show that the optimized scatterer can produce an ultra-strong, ultra-narrow microjet with a power enhancement of ∼ 30 and a full width at half maximum (FWHM) of ∼ 0.26λ, and the microjet is just located at the output face. The microjet keeps compact within the distance range of λ from the output face. These features and effects are explained from the viewpoint of ray optics theory. According to the optimized double-layer scatterer, we further study the multi-frequency focusing features of the microjets, and find that the microjet remains good features at harmonic frequencies 2f
0 and 3f
0. In addition, we investigate the effect of an Au sphere presence in the center of the microjet on the power distribution. The results show that a spherical dark spot with a size similar to that of the Au sphere emerges in the area where the Au sphere is placed. The feature can be used to measure the size of a metallic particle.
Effects of the velocity on the reversible-irreversible transition in a periodically sheared vortex system
Authors: Miyagawa K , Maegochi S , Ienaga K , Kaneko S , Okuma S
Published: July 2021

A reversible-irreversible transition (RIT) is studied using a periodically-driven vortex system in an amorphous film with random pinning that causes local shear, as a function of shear amplitude d. The relaxation time to reach the steady state exhibits a power-law divergence at a threshold value dc
with critical exponents in agreement with the values predicted for an absorbing phase transition in the two-dimensional (2D) directed-percolation (DP) universality class. In our previous work, the experiment was conducted at relatively high frequency f, giving rise to a large mean vortex velocity v. Here we use lower f to study the effects of reduced v and increased dynamic pinning on the RIT. The results show that the critical behavior of RIT stays essentially unchanged, while we find a trend for dc
to increase with decreasing v. We will propose a possible model to qualitatively explain this unexpected result.
Peak Effects in 2H-NbSe2 Single Crystals Induced by Particle Irradiations
Authors: Li Wenjie , Pyon Sunseng , Okayasu Satoru , Tamegai Tsuyoshi
Published: July 2021

Effects of three kinds of columnar defects in NbSe2 single crystals introduced by 320 MeV Au irradiation with a dose equivalent matching field B
Φ up to 4 T were studied. Through the magnetization measurement using a SQUID magnetometer, two pronounced peak effects in the external field dependence of critical current density (J
c) were observed in crystals introduced with splayed and tilted columnar defects. In crystals with splayed columnar defects, J
c at the peak field reaches the maximum for splay angle θ
CD = ±10°, which is a little different from that found in YBa2Cu3O7 and iron-based superconductors, where optimal θ
CD is equal to ±5°.
Electronic Structure of Novel Superconductor (Ca1-x
Sr
x
)Pd3P
Authors: Hase I , Yanagisawa T , Iyo A , Fujihisa H , Gotoh Y , Eisaki H , Kawashima K
Published: July 2021

In this paper we report the results of the first-principles calculations for (Ca1-x
Sr
x
)Pd3P for various crystal structures observed in experiment. The calculated electron specific heat coefficient shows a good agreement with the experimental values. We found the centrosymmetric phase has a higher density of state at the Fermi level than that of the non-centrosymmetric phase. Possible parity mixing in the non-centrosymmetric phase is estimated as small in this system.
Effect of co-substitution on superconductivity in (Y, Ca)(Ba, Sr)2Cu4O8 prepared by the molten KOH method
Authors: Imigi A , Kawamata T , Noji T , Kato M
Published: July 2021

Effect of co-substitution of Ca and Sr in the Y-124 phase of Y1-x
CaxBa2-y
Sr
y
Cu4O8 has been investigated. Polycrystalline samples of Y1-x
CaxBa2-y
Sr
y
Cu4O8 with 0 ≤ x(Ca) ≤ 0.2 and 0 ≤ y(Sr) ≤ 0.2 have been prepared by the molten KOH method. The lattice parameters decrease with increasing y(Sr), indicating that the smaller Sr ions are systematically substituted for the larger Ba ions. The value of Tc
increases from 83 K to ∼ 90 K through the Sr-substitution for x(Ca) = 0, while Tc
∼ 90 K are almost independent of y(Sr) for x(Ca) = 0.1 and 0.2.
Effect of the fluorine substitution for oxygen in the heavily Pb-doped Bi-2212 phase of (Bi, Pb)2(Sr, Ba)2CaCu2O8
Authors: Ito R , Kawamata T , Noji T , Kato M
Published: July 2021

Polycrystalline samples of the Bi-2212 phase of Bi2−x
Pb
x
Sr2CaCu2O8−z
F
z
with x(Pb) = 0.6 and 1.0 have been prepared. All the samples are almost of the single phase with the Bi-2212 structure for x(Pb) = 0.6. The value of Tc
∼ 82 K for z(F) = 0 increases up to 86–88 K for z(F) = 0.2–0.6. This may be due to the decrease in the amount of vacancy at the O-site by the introduction of F−. In addition, we have successfully synthesized the partially Ba-substituted Bi-2212 phase of Bi1.4Pb0.6Sr2−y
Ba
y
CaCu2O7.8F0.2 with 0 ≤ y(Ba) ≤ 0.5. Tc
increases up to 98 K for y(Ba) = 0.5. The enhancement of Tc
through the Ba-substitution may be due to the increase in the distance between Cu and the apical oxygen.
Growth and Characterizations of Iron-based Superconductor (Ba1-x
Rb
x
) Fe2As2 Single Crystals
Authors: Ren T. , Pyon S. , Tamegai T.
Published: July 2021

Novel nematic states as well as remarkable superconducting properties were reported in iron-based superconductors. We synthesized high-quality single crystals of (Ba1-x
Rb
x
)Fe2As2 close to the optimal composition of x ≈ 0.4, and have characterized normal state and superconducting properties for pristine and proton irradiated samples. The highest Tc
was found to be ∼36.6 K for pristine samples. A maximum critical current density of 12 MA/cm2 was achieved in a proton irradiated sample, which is comparable to that in irradiated (Ba0.6K0.4) Fe2As2. Twin boundaries were observed optically in both non-doped and under-doped samples. We also attempted local magnetic field measurements induced by transport current in a sample with twin boundaries for future exploration of nematic states in different regions of doping.
Study on Novel Jointing Technique of Soldered-stacked HTS Wires
Authors: Qian Gang , Yin Meiying , Wang Mingyang , Li Zhuyong , Guan Shufeng , Jin Zhijian
Published: July 2021

In high temperature superconducting (HTS) applications, joining two HTS wires is considered as an essential process for extending the available length. Many soldering and diffusion joints have been designed in recent years, but these joints mainly focused on joining two HTS virgin tapes with 4mm width and 0.15mm thickness. As for the recently developed soldered-stacked (SS) HTS wire, it does not have applicable methods of joining. In this paper, we proposed a novel technique to join two SS wires by soldering and stacking, and measured the joint resistance to demonstrate its feasibility of engineering. First, we join separate layers in SS wires using spot-welding machine. Second, we coat these layers in the solder bath. This method allows making joints and manufacturing SS wires simultaneously. This work will introduce the specification of this jointing method for SS wire, and the related experimental results will provide a reference for the SS wire joint fabrication in the future.
Investigating the flux jump behaviour during single waveform control pulsed field magnetization of GdBaCuO superconducting bulk
Authors: Caunes A A , Ida T , Watasaki M , Izumi M
Published: July 2021

We aimed to improve the trapped magnetic flux density obtained with a waveform control pulsed field magnetization (WCPM) by using a negative feedback control of the magnetic flux density on the growth sector boundary of a GdBaCuO superconducting bulk sample. The WCPM method with negative feedback control has previously shown that it could help increase the trapped magnetic flux density, compared to conventional passive pulsed flux magnetization, if the magnetic field penetrates the bulk centre substantially using a flux jump. The flux jump sometimes greatly changes the magnetic and thermal state of the bulk, which limits the maximum trapped magnetic field. The active control method of the applied magnetic field helps to overcome this limit if the control conditions are appropriate. While searching for the ideal control conditions of the WCPM, the magnetization characteristics have been investigated. We found that the flux jump, which assists the flux in penetrating the centre of the bulk, can be “slowed down” thanks to the negative-feedback WCPM. This operation helped to decrease the heat generated by the moving flux inside the bulk and reduced the temperature rise, which contributed to the increase of the trapped magnetic flux density.
Metallic Contaminant Detection in Liquids using a High-Tc RF-SQUID
Authors: Sagawa M , Hayashi K , Ohtani T , Tanaka S
Published: July 2021

We have developed a system using high-temperature radio frequency superconducting quantum interference device (RF-SQUID) for detecting metallic contaminants in the liquid component of a lithium-ion battery. Although we have executed detection experiments using a simulated system without liquid in the past[1], we have developed a new system to inspect real liquid components. Small cylindrical metallic contaminant samples were fabricated using a gallium-focused ion beam to evaluate the detection performance. Tap water containing the metallic contaminant sample was poured into the tube using a pump, and the magnetic signal of the contaminant matter was detected using the RF-SQUID. Among the tested small metallic contaminant samples, the volume of a minimum detectable metallic contaminant was evaluated to be 2 × 104 μm3, which corresponded to that of a spherical sample with a diameter of 33 μm and a sensitivity of a signal-to-noise ratio of more than three. Moreover, the dependence of the detected signal strength on the volume of the metallic contaminant samples is discussed here.
Estimation of Critical Current of HTS RF-SQUID
Authors: Ohtani R , Hayashi K , Sagawa M , Ariyoshi S , Tanaka S
Published: July 2021

The operation of the RF SQUID is restricted by the condition that the inductance parameter β
L must be in the range of 1−3. However, since both ends of the Josephson junction (JJ) of RF-SQUID are shorted, it is difficult to non-destructively estimate the critical current (IC
). Thus, we proposed a technique for the non-destructive measurement of the IC
of a high-temperature superconducting (HTS) RF-SQUID ring by evaluating the behaviour of the flux in superconducting thin films using a SQUID magnetometer. A superconducting ring sample with JJ was placed below the HTS SQUID magnetometer and cooled down to 77 K. The change in the SQUID output was monitored on application of the magnetic field. When increasing the field, the waveforms indicated that the screening current of the ring sample exceeded the I
C of the JJ, and the JJ became a normal-conducting state. As a result, we estimated the IC
of the JJ of this sample as 134 μA using the values of mutual inductance and the coupling coefficient α between the coil and the sample.
Improvement of Plug-in Wire for 200-pixel Superconducting Tunnel Junction X-ray Detector Array on Helium Three Cryostat
Authors: Shiki Shigetomo , Fujii Go , Ukibe Masahiro
Published: July 2021

The design of plug-in wire system is improved for 200-pixel superconducting tunnel junction (STJ) array of X-ray detector on a helium three cryostat. The electrical connections between the STJ array to the room temperature electronics consists of plural wire modules, which have connectors at the both ends. A flexible coaxial cable with electrical conductors of stainless steel (SUS-FFC) is manufactured and attached to make the electrical connection between room temperature to the 3 K stage. After the installation of SUS-FFC, temperature of the cold stage is 302 mK, and the holding time is more than 115 hours. Compared with the previous setup, the temperature of 3He stage decreased 5 mK, and the holding time increased 30 hours.
Evaluation of flux trapping moat position on AQFP cell performance
Authors: Fourie Coenrad J , Takeuchi Naoki , Jackman Kyle , Yoshikawa Nobuyuki
Published: July 2021

With recent advances in InductEx and the TetraHenry numerical engine, it is now possible to analyze the coupling of trapped flux in moats to superconductor circuit structures. Here we show the analysis of moat position in the layout of an adiabatic quantum-flux-parametron (AQFP) buffer cell on the coupling to critical inductors such as the load inductor. This inductor is often carefully laid out to balance current flow and cancel out stray coupling between clock and dc current excitation lines. We investigate the effect of trapped flux that couples asymmetrically to the circuit—either due to the moat position and shape or due to only one of a symmetrical duo of moats being filled with a trapped fluxon—on circuit operating margin and performance. We conclude with suggestions on moat placement to reduce the chances of circuit failure when fluxons are trapped in the moats.
Heat Load Calculations on an HTS Coil Integrated into a Small Satellite during a Sun-Synchronous Low Earth Orbit
Authors: Olatunji J R , Acheson C , Szmigiel M , Wimbush S C , Long N J
Published: July 2021

High-temperature superconductivity (HTS) has the potential to be a useful technology for space applications, allowing for high current densities and magnetic field generation in compact devices. However, HTS requires cryogenic temperatures and it is not well understood how this can best be achieved in a space environment. Using a modelling approach, the expected heat load on a hypothetical 3U CubeSat with an HTS coil during a sun-synchronous low Earth orbit was predicted. The direction and magnitude of solar, albedo and infrared incident radiation toward the satellite was calculated for each orbital position of a circular 732 km, Ω = 0° longitude of ascending node orbit. Using a finite element approach, the surface radiosity and temperature of the CubeSat was predicted and validated. Finally, the instantaneous heat load on the HTS magnet, which generates a 1T magnetic field, was calculated as a function of orbital position. This study provides technical information about the characteristics of the refrigeration device required to maintain cryogenic temperatures for an HTS coil on a space faring vessel, such as a portable cryocooler. Selection and design of a satellite cooling system must be optimised according to the calculated heat load and available solar power.
Improvement of the Damping Factor at Low Speed in Electrodynamic Suspension System for the JR Maglev
Authors: Betsunoh R , Ohashi S
Published: July 2021

The electrodynamic suspension system (EDS) is one of the magnetic levitation system and has advantage of stable levitation without the gap control. However, the damping factor of the EDS system is not enough. Once the oscillation of the bogie occurs by the external disturbance, it does not converge immediately. The additional damper system is needed, so the damper coil system is installed. By the semi-active damper system, the levitation stability is improved. This paper discusses about superconducting Maglev system as application of the EDS system. Superconducting Maglev has been the magnetic levitation system developed by Central Japan Railway Company and Railway Technical Research Institute. The operation speed of the train is v = 120[m/sec]. At low speed range such as v = 60-80[m/sec], the damping factor is smaller than that of the normal operation v = 120[m/sec], and it is difficult to keep the stable levitation. In this paper, running simulation when the bogie passes large displacement at low speed is undertaken, and the improved switching method for the semi-active damper system at low speed and large displacement is discussed. From the results, to increase the period that the damper coil works. The damping factor becomes larger, and the bogie keeps the levitation.
Design of the Magnetic Circuit to Improve Stability of the Magnetic Bearing Using HTS
Authors: Minamitani Marin , Takimura Satoshi , Ohashi Shunsuke
Published: July 2021

This paper proposes the design of the magnetic circuit to improve stability of the magnetic bearing using HTS. From the rotational characteristic, it is shown that if the flux of the rotor is concentrated to the outer part of the HTS, the rotor will be able to rotate stability. In order to achieve stable rotation, the yoke equipped ring type rotor is proposed. The ring type permanent magnet equipped the yoke is used of this rotor. The change in the flux when the gap between the yoke and the permanent magnet, the yoke thickness and the width are changed is considered. As each value increases, the flux amount increases. As the gap between the yoke and the permanent magnet increases, the flux distribution is more concentrated to the outer part of the HTS. Considering the overall diameter, the boundary where the increasing rate decreases is adopted as the optimum value. In the yoke thickness and the width, the minimum value where the magnetic saturation is not observed is adopted as the optimum value. As a result, the magnetic circuit that the flux is concentrated to the outer part of the HTS is designed. By concentrating the flux to the outer part of the HTS, the stable rotation is given.
Design of a 500 kW partially superconducting flux modulation machine for aircraft propulsion
Authors: Dorget R , Ayat S , Biaujaud R , Tanchon J , Lacapere J , Lubin T , Lévêque J
Published: July 2021

Electric propulsion is seen as a potential solution for reducing greenhouse gas emissions from the aircraft industry. However, electrical machines must achieve high power to mass ratios (PtM) to meet aviation requirements. Superconducting technologies are a promising option for creating compact and efficient machines. Indeed, superconductors make it possible to generate large magnetic fields while reducing the need for ferromagnetic materials. In previous works, a 50 kW partially superconducting flux modulation machine has been realised. The flux modulation machine is an unconventional topology where the inductor is composed by a large static superconducting coil and rotating superconducting bulks acting as magnetic field shields. This topology allows controlling the inductor excitation while being brushless. In this paper, we design a 500 kW flux modulation machine considering the results of the 50 kW prototype and the constraints due to the structure change of scale. The presented machine aims to reach a power-to-mass ratio of 10 kW/kg.
Experimental investigation of the thermal performance of the thermosyphon cooling system with rotating
Authors: Yamaguchi K , Takei S , Izumi M
Published: July 2021

Rotating machine applications with superconductors attract much interest in the industry. For maintaining the operating temperature of high-temperature superconductor (HTS) field poles, a sophisticated cooling system is required. A thermosyphon (TS) is one of the ways for this purpose. The cryo-mechanical system composition is relatively simple, lightweight, and based on natural convection therefore not using any mechanical pump. It can supply the refrigerant from the static condenser part to the rotating evaporator part by using a successful rotary joint. The operating temperature of the TS cooling system depends on the refrigerant. Considering the current HTS materials, the suitable refrigerant is neon, hydrogen. Nitrogen which provides a higher operating temperature than neon and hydrogen is employed for future development. In this work, we focused on and investigated the heat transfer capacity of TS using nitrogen as the refrigerant. The heat transfer performance with rotating was also studied. As a result of the experiment, the TS cooling system could maintain the evaporator temperature by rotating. Moreover, it could transfer the 90 W heat load with rotating.