bluuebunny/crossref_metadata_2025 huggingface dataset:
Open Appendicectomy under Spinal Anesthesia—A Valuable Alternative during COVID-19
Authors: Mai Dinh Van Chi , Sagar Alex , Claydon Oliver , Park Ji Young , Tapuria Niteen , Keeler Barrie D.
Published: June 2021

Introduction Concerns relating to coronavirus disease 2019 (COVID-19) and general anesthesia (GA) prompted our department to consider that open appendicectomy under spinal anesthesia (SA) avoids aerosolization from intubation and laparoscopy. While common in developing nations, it is unusual in the United Kingdom. We present the first United Kingdom case series and discuss its potential role during and after this pandemic.

Methods We prospectively studied patients with appendicitis at a British district general hospital who were unsuitable for conservative management and consequently underwent open appendicectomy under SA. We also reviewed patient satisfaction after 30 days. This ran for 5 weeks from March 25th, 2020 until the surgical department reverted to the laparoscopic appendicectomy as the standard of care. Main outcomes were 30-day complication rates and patient satisfaction.

Results None of the included seven patients were COVID positive. The majority (four-sevenths) had complicated appendicitis. There were no major adverse (Clavien-Dindo grade III to V) postoperative events. Two patients suffered minor postoperative complications. Two experienced intraoperative pain. Mean operative time was 44 minutes. Median length of stay and return to activity was 1 and 14 days, respectively. Although four stated preference in hindsight for GA, the majority (five-sevenths) were satisfied with the operative experience under SA.

Discussion Although contraindications, risk of pain, and specific complications may be limiting, our series demonstrates open appendicectomy under SA to be safe and feasible in the United Kingdom. The technique could be a valuable contingency for COVID-suspected cases and patients with high-risk respiratory disease.
The SARS-CoV-2 pandemic: the race to trace: contact tracing scale-up in San Francisco—early lessons learned
Authors: Reid Michael , Enanoria Wayne , Stoltey Juliet , Philip Susan , Fuchs Jonathan , Lockwood Amy , Krueger Elizabeth , White Karen , Celentano Jessica , Rutherford George , Scheer Susan , Nguyen Trang , Sachdev Darpun
Published: June 2021

In order to effectively control spread of coronavirus 2019 (COVID-19), it is essential that jurisdictions have the capacity to rapidly trace close contacts of each and every case. Best practice guidance on how to implement such programs is urgently needed. We describe the early experience in the City and County of San Francisco (CCSF), where the City’s Department of Health expanded contact tracing capability in anticipation of changes in San Francisco’s ‘shelter in place’ order between April and June 2020. Important prerequisites to successful scale-up included a rapid expansion of the COVID-19 response workforce, expansion of testing capability, and other containment resources. San Francisco’s scale-up offers a model for how other jurisdictions can rapidly mobilize a workforce. We underscore the importance of an efficient digital case management system, effective training, and expansion of supportive service programs for those in quarantine or isolation, and metrics to ensure continuous performance improvement.
Appearance of chaos and hyperchaos in evolving pendulum network
Authors: Munyaev Vyacheslav O. , Khorkin Dmitry S. , Bolotov Maxim I. , Smirnov Lev A. , Osipov Grigory V.
Published: June 2021

The study of deterministic chaos continues to be one of the important problems in the field of nonlinear dynamics. Interest in the study of chaos exists both in low-dimensional dynamical systems and in large ensembles of coupled oscillators. In this paper, we study the emergence of chaos in chains of locally coupled identical pendulums with constant torque. The study of the scenarios of the emergence (disappearance) and properties of chaos is done as a result of changes in (i) the individual properties of elements due to the influence of dissipation in this problem and (ii) the properties of the entire ensemble under consideration, determined by the number of interacting elements and the strength of the connection between them. It is shown that an increase of dissipation in an ensemble with a fixed coupling force and a number of elements can lead to the appearance of chaos as a result of a cascade of period-doubling bifurcations of periodic rotational motions or as a result of invariant tori destruction bifurcations. Chaos and hyperchaos can occur in an ensemble by adding or excluding one or more elements. Moreover, chaos arises hard since in this case, the control parameter is discrete. The influence of the coupling strength on the occurrence of chaos is specific. The appearance of chaos occurs with small and intermediate coupling and is caused by the overlap of the existence of various out-of-phase rotational mode regions. The boundaries of these areas are determined analytically and confirmed in a numerical experiment. Chaotic regimes in the chain do not exist if the coupling strength is strong enough. The dimension of an observed hyperchaotic regime strongly depends on the number of coupled elements.
Contrasting natal origin and movement history informs recovery pathways for three lowland river species following a mass fish kill
Authors: Thiem Jason D. , Baumgartner Lee J. , Fanson Ben , Sadekov Aleksey , Tonkin Zeb , Zampatti Brenton P.
Published: June 2021

Understanding the spatial and temporal scales over which key population processes occur is fundamental to effective fisheries management, especially when informing recovery actions following extreme events. In 2018–19, hypoxia-induced fish kills occurred in the lower Darling River, south-eastern Australia. We collected carcasses of three potamodromous species that perished during these events to reconstruct their lifetime movements and identify potential recovery mechanisms. Golden perch Macquaria ambigua, Murray cod Maccullochella peelii and silver perch Bidyanus bidyanus otolith 87Sr/86Sr profiles were compared with water 87Sr/86Sr ratios to better understand natal provenance and movement history, and to identify the scale at which migration influences population processes. Golden perch were predominantly locally spawned (Darling River), although we found some evidence of emigration into the nearby Murray River early in life and return movements into the Darling River. Murray cod were mainly locally spawned and thereafter lifelong residents, with some evidence of stocking supplementing populations. Silver perch were mostly immigrants, with the Murray River (>500 km away) the principal source of fish. For recovery of native fish populations to be effective in the Darling River, recovery actions are required that incorporate knowledge on the relevant spatial and temporal scales over which life history processes occur.
A reverse stroke characterizes the force generation of cardiac myofilaments, leading to an understanding of heart function
Authors: Hwang Yongtae , Washio Takumi , Hisada Toshiaki , Higuchi Hideo , Kaya Motoshi
Published: June 2021

Significance

Force measurements on cardiac myosin molecules and polymerized myofilaments demonstrated that single molecules transition back and forth between three molecular conformations when bound to an actin filament that is experiencing a resistive load, as would be the case in a contracting heart. These distinct positions correspond to a pre–power stroke state and two post–power stroke states. The experimental data are coupled with modeling to predict ensemble behavior and collectively demonstrate that the reversal stroke is a key feature of cardiac muscle that allows for the maintenance of the high force production necessary for cardiac contraction and rapid cardiac relaxation in the heart. Thus, the study provides evidence that the reverse stroke may be a critical feature for normal cardiac function.
Self-adaptive and efficient propulsion of Ray sperms at different viscosities enabled by heterogeneous dual helixes
Authors: Wang Panbing , Al Azad M. A. R. , Yang Xiong , Martelli Paolo R. , Cheung Kam Yan , Shi Jiahai , Shen Yajing
Published: June 2021

Significance

For decades, the propulsion of sperms has been traditionally attributed to the beating or rotating of the soft tails. However, this work disclosed an unusual swimming model of Ray sperms whose propulsion is from not only the helical tail but also the unique spiral head (i.e., the head can contribute ∼31% of the force in propulsion). Such a propulsion mechanism provides Ray sperms with high adaptability to large environmental viscosities along with advantages in linearity, straightness, and efficiency. This study expands our knowledge on the microorganisms’ motion and provides inspirations for engineering design.
Altered amino acid profile in patients with SARS-CoV-2 infection
Authors: Rees Chris A. , Rostad Christina A. , Mantus Grace , Anderson Evan J. , Chahroudi Ann , Jaggi Preeti , Wrammert Jens , Ochoa Juan B. , Ochoa Augusto , Basu Rajit K. , Heilman Stacy , Harris Frank , Lapp Stacey A. , Hussaini Laila , Vos Miriam B. , Brown Lou Ann , Morris Claudia R.
Published: June 2021

Low plasma arginine bioavailability has been implicated in endothelial dysfunction and immune dysregulation. The role of arginine in COVID-19 is unknown, but could contribute to cellular damage if low. Our objective was to determine arginine bioavailability in adults and children with COVID-19 vs. healthy controls. We hypothesized that arginine bioavailability would be low in patients with COVID-19 and multisystem inflammatory syndrome in children (MIS-C). We conducted a prospective observational study of three patient cohorts; arginine bioavailability was determined in asymptomatic healthy controls, adults hospitalized with COVID-19, and hospitalized children/adolescents <21 y old with COVID-19, MIS-C, or asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection identified on admission screen. Mean patient plasma amino acids were compared to controls using the Student’s
t
test. Arginine-to-ornithine ratio, a biomarker of arginase activity, and global arginine bioavailability ratio (GABR, arginine/[ornithine+citrulline]) were assessed in all three groups. A total of 80 patients were included (28 controls, 32 adults with COVID-19, and 20 pediatric patients with COVID-19/MIS-C). Mean plasma arginine and arginine bioavailability ratios were lower among adult and pediatric patients with COVID-19/MIS-C compared to controls. There was no difference between arginine bioavailability in children with COVID-19 vs. MIS-C. Adults and children with COVID-19 and MIS-C in our cohort had low arginine bioavailability compared to healthy adult controls. This may contribute to immune dysregulation and endothelial dysfunction in COVID-19. Low arginine-to-ornithine ratio in patients with COVID-19 or MIS-C suggests an elevation of arginase activity. Further study is merited to explore the role of arginine dysregulation in COVID-19.
AP-1 is a temporally regulated dual gatekeeper of reprogramming to pluripotency
Authors: Markov Glenn J. , Mai Thach , Nair Surag , Shcherbina Anna , Wang Yu Xin , Burns David M. , Kundaje Anshul , Blau Helen M.
Published: June 2021

Significance

Reprogramming of somatic cells holds tremendous therapeutic promise. Here we show that a key barrier to this process is a DNA binding protein named activator protein 1 (AP-1). We find that AP-1 acts sequentially to first maintain the somatic state by turning genes on and then to block the initiation of the new cellular program by acting as a repressor of gene transcription. Crucially, we were able to uncover this feature of AP-1 by using the heterokaryon system of reprogramming, in which human fibroblasts are fused to an excess of mouse embryonic stem cells to favor the induction of the embryonic stem cell program in the fibroblast.
Hymenoscyphus fraxineus (ash dieback).
Authors: Needham Jessica , Webber Joan
Published: June 2021

H. fraxineus is an anamorphic fungal pathogen that causes ash dieback. Due to the severity of ash dieback H. pseudoalbidus has been on the EPPO Alert list since 2007. It is not known what caused the emergence of this 'new' disease (NAPPO, 2009). Its spread in Europe is thought to be mainly by ascospores, but infected nursery saplings may carry the fungus to new areas. The entire natural range of known hosts, including North Africa, Russia and south-west Asia (USDA-ARS, 2009), is currently threatened by ash dieback, with large areas already affected (Pautasso et al., 2013). Little is known about the susceptibility of the other species of ash in temperate zones.
Pseudocercospora ulei (South American leaf blight of rubber (SALB)).
Authors: Evans Harry
Published: June 2021

The invasive potential of SALB has been illustrated by the devastating impact that it has had on attempts to develop rubber production in the Americas. Rapid epidemic development of the disease under humid conditions can destroy young rubber plants. Control methods are expensive and reduce the economic value of the crop. The disease poses a major threat to the large rubber producing areas in West Africa and South-East Asia (Edathil, 1986), where strict quarantine measures are enforced to prevent entry of the pathogen (Jayasinghe, 1998; FAO, 2011).
Bactericera cockerelli (tomato/potato psyllid).
Authors: Munyaneza Joseph E.
Published: June 2021

B. cockerelli is one of the most destructive potato pests in the western hemisphere. It was recognized in the early 1900s that B. cockerelli had the potential to be an invasive and harmful insect, particularly in western United States and Mexico (Šulc, 1909; Crawford, 1914; Compere, 1915; 1916; Essig, 1917). By the 1920s and 1930s, B. cockerelli had become a serious and destructive pest of potatoes in most of the southwestern United States, giving rise to the description of a new disease that became known as 'psyllid yellows' (Richards, 1928; 1931; 1933; Binkley, 1929; Richards and Blood, 1933; List and Daniels, 1934; Pletsch, 1947; Wallis, 1955). In recent years, other solanaceous crops, including tomato, pepper, eggplant, tobacco and tamarillo in a number of geographic areas have suffered extensive economic losses associated with B. cockerelli outbreaks (Trumble, 2008, 2009; Munyaneza et al., 2007a, b; 2008; 2009a, b, c, d; Liefting et al., 2008; 2009; Secor et al., 2009; Espinoza, 2010; Munyaneza, 2010; Crosslin et al., 2010; Rehman et al., 2010; Crosslin et al., 2012a, b; Munyaneza, 2012). Despite being a native of North America, B. cockerelli is also found in Central America and has recently invaded New Zealand, where it has caused extensive damage to indoor and outdoor solanaceous crops (Teulon et al., 2009; Thomas et al., 2011). B. cockerelli has recently been placed on the list of quarantine pest in EPPO region (EPPO, 2012).
Tobacco streak virus (tobacco streak).
Authors: Tzanetakis Ioannis E.
Published: June 2021

TSV is prevalent in south-eastern Brazil, and can limit yields of soyabeans in some years (Costa and Carvalho, 1961). Epidemics of soyabean bud blight, caused by TSV, were monitored in two soyabean cultivars sown on seven different dates in 1987-88 in Arapoti County, Parana. The highest final level of disease incidence was 60% in 1987 and 90% in 1988 (Almeida et al., 1994a). Brazilian bud blight is also a serious disease in the Santa Fe province of Argentina (Laguna et al., 1988). It occurs in the USA (Fagbenle and Ford, 1970; Kaiser et al., 1982; Sherwood and Jackson, 1985) but is of no economic significance on soyabeans because conditions are not conducive to the development of the problem. TSV presents a major problem in sunflower production in the Indian subcontinent as severe necrosis symptoms may lead to major losses (Bhat et al., 2002).
Candidatus Phytoplasma pini (pine witches'-broom phytoplasma).
Authors: Davis Robert E. , Zhao Yan
Published: June 2021

'Ca. Phytoplasma pini' is a member of phytoplasma 16S rRNA gene RFLP group XXI, subgroup XXI-A. It has been identified in a number of European countries, including Germany, Poland, Lithuania, Spain, Czech Republic and Croatia. Outside of Europe it has been identified in China and Mozambique. A related strain has also been identified in Maryland, USA. In the USA, favourable climatic conditions and wide availability of potential host plants of the phytoplasma, suggest that the potential for spread of 'Ca. Phytoplasma pini' could be significant. Host plants include Pinus sylvestris, P. halepensis, P. mugo, P. banksiana, P. nigra, P. tabuliformis, Abies procera and Tsuga canadensis. Symptoms include the formation of ball-like growths containing dwarfed needles, yellowed or reddish needles and the loss of needles. It is transmitted by insect vectors that are currently unknown.
Agropyron mosaic virus (Agropyron mosaic virus).
Authors: Stewart Lucy , Hodge Brian
Published: June 2021

AgMV has been reported in North America and Europe and is not considered a major pathogen on wheat, although it has pathogenic potential if present at high incidences (Slykhuis, 1962a). AgMV is transmitted by the widely distributed eriophyid mite Abacarus hystrix and can be mechanically transmitted by rub-inoculation with infected plant sap experimentally. No clear evidence is available of AgMV increasing in distribution.
Pear blister canker viroid.
Authors: Hammond Rosemarie W.
Published: June 2021

Pear blister canker disease, first reported in France in the 1960's, is caused by pear blister canker viroid (PBCVd). Diseases can occur in several cultivars of pear (Pyrus communis), its major host, but most pear cultivars are tolerant and do not produce symptoms of infection. PBCVd was initially reported in pear and quince, followed by wild pear and nashi and can experimentally infect species in other genera (Chaenomeles, Cydonia, Sorbus, Malus). Transmission through mechanical inoculation from pruning tools and grafting to infective propagative materials is a potential pathway for spread; no animal vector is known and it is not known to be seed transmitted. PBCVd has been reported in several European countries, Malta, Tunisia, Turkey, Australia, Japan, China, and the Americas; the geographic distribution may be underestimated because of symptomless infections in certain hosts. PBCVd was placed on the A1 list in Canada in 1995, listed as a quarantine pest in the United States in 1989, is regarded as quarantine pathogen for Australia, and is listed in a certification scheme to produce clean Pyrus and Cydonia sp. planting material in an OEPP/EPPO Bulletin in 1999 (OEPP/EPPO, 1999).
Raffaelea quercivora (Japanese oak wilt).
Authors: Masuya Hayato
Published: June 2021

Raffaelea quercivora, together with ambrosia beetle Platypus quercivorus as a vector, is the causal agent of Japanese oak wilt. P. quercivorus occurs from south to east Asia, including Japan, and is associated with trees in the Fagaceae family. R. quercivora is considered native to Japan, Taiwan, Indonesia, Thailand and Vietnam. In Japan, Quercus serrata and Q. crispula [Q. mongolica] are particularly susceptible to Japanese oak wilt, with high rates of mortality. Although there have been reports of the co-occurrence of R. quercivora and P. quercivorus outside of Japan, tree mortality caused by this species complex has never been recorded in these cases. R. quercivora is not on an alert list or listed as a regulated pest in any part of its native range. Although R. quercivora/P. quercivorus are not considered invasive, if they were introduced into susceptible oak forests, possibly via international transport of wood products, there is potential for them to cause extensive tree mortality in other geographic regions.
Sclerophthora rayssiae var. zeae (brown stripe downy mildew of maize).
Authors: Magill Clint
Published: June 2021

The first record of brown stripe downy mildew of maize occurred in India in the early 1960s. In 1967, the pathogen was defined as Sclerophthora rayssiae var. zeae by Payak and Renfro. It spread rapidly across India, especially in regions with over 100 cm of annual rainfall and into neighbouring countries, probably via seed transfer. It has been effectively controlled by the use of resistant hybrids and seed treatment. It is not reported to be an invasive species.
Tomato apical stunt viroid.
Authors: Hammond Rosemarie W.
Published: June 2021

Tomato apical stunt viroid (TASVd) is a serious pathogen of tomato. Pathways for introduction include tomato seedlings, tomato seeds and ornamentals. If spread to tomato, considerable losses could result. TASVd is spread easily through plant sap, e.g. during pruning and propagation, and there is some evidence of insect transmission in the greenhouse. No symptoms appear on infected ornamental solanaceous plants, but these plants can act as a reservoir for the spread of viroids in tomato production, especially in greenhouse conditions. TASVd outbreaks in tomato are rare although it has occurred in several countries in Asia, Africa and Europe. The economic impact of TASVd in tomato production is not known, but heavy yield losses may result from infection with certain strains. This viroid has not been reported as an invasive species.
Anguina tritici (wheat seed gall nematode).
Authors: Skantar Andrea M.
Published: June 2021

Anguina tritici, commonly referred to as wheat seed gall nematode, is the cause of ear-cockle disease. It was the first plant-parasitic nematode to be described in the scientific literature in 1743. Its host range includes wheat, triticale, rye, and related grasses; the primary host is wheat. Ear cockle in the past was reported in all major wheat growing areas. However, physical and mechanical methods for separating infected galls from seed have eradicated the nematode from the western hemisphere. It remains a problem in several countries in the Near and Middle East, the Asian Subcontinent and Eastern Europe, most likely due to poor awareness and lack of campaigns for establishing clean seed. A. tritici is on the U.S. Pests of Economic and Environmental Importance List, and on the 'Harmful Organism Lists' for Argentina, Brazil, Chile, Colombia, Ecuador, Egypt, Guatemala, Indonesia, Israel, Madagascar, Namibia, Nepal, New Zealand, Paraguay, Peru, South Africa, Taiwan, Thailand, Timor-Leste and Uruguay.
Loss of direct adrenergic innervation after peripheral nerve injury causes lymph node expansion through IFN-γ
Authors: Chen Chien-Sin , Weber Jasmin , Holtkamp Stephan Jonas , Ince Louise Madeleine , de Juan Alba , Wang Chen , Lutes Lydia , Barnoud Coline , Kizil Burak , Hergenhan Sophia Martina , Salvermoser Johanna , Lasch Manuel , Deindl Elisabeth , Schraml Barbara , Baumjohann Dirk , Scheiermann Christoph
Published: June 2021

Peripheral nerve injury can cause debilitating disease and immune cell–mediated destruction of the affected nerve. While the focus has been on the nerve-regenerative response, the effect of loss of innervation on lymph node function is unclear. Here, we show that the popliteal lymph node (popLN) receives direct neural input from the sciatic nerve and that sciatic denervation causes lymph node expansion. Loss of sympathetic, adrenergic tone induces the expression of IFN-γ in LN CD8 T cells, which is responsible for LN expansion. Surgery-induced IFN-γ expression and expansion can be rescued by β2 adrenergic receptor agonists but not sensory nerve agonists. These data demonstrate the mechanisms governing the pro-inflammatory effect of loss of direct adrenergic input on lymph node function.
Finding Short-Range Parity-Time Phase-Transition Points with a Neural Network
Authors: Lei Songju , Bai Dong , Ren Zhongzhou , Lyu Mengjiao
Published: June 2021

The non-Hermitian PT-symmetric system can live in either unbroken or broken PT-symmetric phase. The separation point of the unbroken and broken PT-symmetric phases is called the PT-phase-transition point. Conventionally, given an arbitrary non-Hermitian PT-symmetric Hamiltonian, one has to solve the corresponding Schrödinger equation explicitly in order to determine which phase it is actually in. Here, we propose to use artificial neural network (ANN) to determine the PT-phase-transition points for non-Hermitian PT-symmetric systems with short-range potentials. The numerical results given by ANN agree well with the literature, which shows the reliability of our new method.
PTC: Full and Drift Particle Orbit Tracing Code for α Particles in Tokamak Plasmas
Authors: Wang Feng , Zhao Rui , Wang Zheng-Xiong , Zhang Yue , Lin Zhan-Hong , Liu Shi-Jie
Published: June 2021

Fusion born α particle confinement is one of the most important issues in burning plasmas, such as ITER and CFETR. However, it is extremely complex due to the nonequilibrium characteristics, and multiple temporal and spatial scales coupling with background plasma. A numerical code using particle orbit tracing method (PTC) has been developed to study energetic particle confinement in tokamak plasmas. Both full orbit and drift orbit solvers are implemented to analyze the Larmor radius effects on α particle confinement. The elastic collisions between alpha particles and thermal plasma are calculated by a Monte Carlo method. A triangle mesh in poloidal section is generated for electromagnetic fields expression. Benchmark between PTC and ORBIT has been accomplished for verification. For CFETR burning plasmas, PTC code is used for α particle source and slowing down process calculation in 2D equilibrium. In future work, 3D field like toroidal field ripples, Alfvén and magnetohydrodynamics instabilities perturbation inducing α particle transport will be analyzed.
Numerical and Experimental Evaluation of Shine-Through Loss and Beam Heating Due to Neutral Beam Injection on EAST
Authors: Wang Jin-Fang , Li Ying-Ying , Wu Bin , Chen Yu-Qing , Li Jun , Xu Yong-Jian , Chen Long-Xi , Hao Bao-Long , Zhou Deng , Huang Juan , Ding Si-Ye , Yang Zhen , Hou Ya-Wei , Liu Xiao-Juan , Xiang Nong
Published: June 2021

This research applies experimental measurements and NUBEAM, ONETWO and TRANSP modules to investigate the shine-through (ST) loss ratio and beam heating percentage of neutral beam injection on EAST. Measurements and simulations confirm that the ST loss ratio increases linearly with beam energy, and decreases exponentially with plasma density. Moreover, using the multi-step fitting method, we present analytical quantitative expressions of ST loss ratio and beam heating percentage, which are valuable for the high parameter long-pulse experiments of EAST.
Revealing the Pressure-Induced Softening/Weakening Mechanism in Representative Covalent Materials
Authors: Xu Tengfei , Zhang Shihao , Legut Dominik , Veprek Stan , Zhang Ruifeng
Published: June 2021

Diamond, cubic boron nitride (c-BN), silicon (Si), and germanium (Ge), as examples of typical strong covalent materials, have been extensively investigated in recent decades, owing to their fundamental importance in material science and industry. However, an in-depth analysis of the character of these materials' mechanical behaviors under harsh service environments, such as high pressure, has yet to be conducted. Based on several mechanical criteria, the effect of pressure on the mechanical properties of these materials is comprehensively investigated. It is demonstrated that, with respect to their intrinsic brittleness/ductile nature, all these materials exhibit ubiquitous pressure-enhanced ductility. By analyzing the strength variation under uniform deformation, together with the corresponding electronic structures, we reveal for the first time that the pressure-induced mechanical softening/weakening exhibits distinct characteristics between diamond and c-BN, owing to the differences in their abnormal charge-depletion evolution under applied strain, whereas a monotonous weakening phenomenon is observed in Si and Ge. Further investigation into dislocation-mediated plastic resistance indicates that the pressure-induced shuffle-set plane softening in diamond (c-BN), and weakening in Si (Ge), can be attributed to the reduction of antibonding states below the Fermi level, and an enhanced metallization, corresponding to the weakening of the bonds around the slipped plane with increasing pressure, respectively. These findings not only reveal the physical mechanism of pressure-induced softening/weakening in covalent materials, but also highlights the necessity of exploring strain-tunable electronic structures to emphasize the mechanical response in such covalent materials.
Magnus Hall Effect in Two-Dimensional Materials
Authors: Xiao Rui-Chun , Wang Zibo , Zhang Zhi-Qiang , Liu Junwei , Jiang Hua
Published: June 2021

The Magnus Hall effect (MHE) is a new type of linear-response Hall effect, recently proposed to appear in two-dimensional (2D) nonmagnetic systems at zero magnetic field in the ballistic limit. The MHE arises from a self-rotating Bloch electron moving under a gradient-electrostatic potential, analogous to the Magnus effect in the macrocosm. Unfortunately, the MHE is usually accompanied by a trivial transverse signal, which hinders its experimental observation. We systematically investigate the material realization and experimental measurement of the MHE, based on symmetry analysis and first-principles calculations. It is found that both the out-of-plane mirror and in-plane two-fold symmetries can neutralize the trivial transverse signal to generate clean MHE signals. We choose two representative 2D materials, monolayer MoS2, and bilayer WTe2, to study the quantitative dependency of MHE signals on the direction of the electric field. The results are qualitatively consistent with the symmetry analysis, and suggest that an observable MHE signal requires giant Berry curvatures. Our results provide detailed guidance for the future experimental exploration of MHE.
Interfacial Charge Transfer Induced Electronic Property Tuning of MoS2 by Molecular Functionalization
Authors: Zhou Si-Han , Zhou Chun-Wei , Yang Xiang-Dong , Li Yang , Zhong Jian-Qiang , Mao Hong-Ying
Published: June 2021

The modulation of electrical properties of MoS2 has attracted extensive research interest because of its potential applications in electronic and optoelectronic devices. Herein, interfacial charge transfer induced electronic property tuning of MoS2 are investigated by in situ ultraviolet photoelectron spectroscopy and x-ray photoelectron spectroscopy measurements. A downward band-bending of MoS2-related electronic states along with the decreasing work function, which are induced by the electron transfer from Cs overlayers to MoS2, is observed after the functionalization of MoS2 with Cs, leading to n-type doping. Meanwhile, when MoS2 is modified with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F
4-TCNQ), an upward band-bending of MoS2-related electronic states along with the increasing work function is observed at the interfaces. This is attributed to the electron depletion within MoS2 due to the strong electron withdrawing property of F
4-TCNQ, indicating p-type doping of MoS2. Our findings reveal that surface transfer doping is an effective approach for electronic property tuning of MoS2 and paves the way to optimize its performance in electronic and optoelectronic devices.
Level Statistics Crossover of Chiral Surface States in a Three-Dimensional Quantum Hall System
Authors: Kausar Rubah , Zheng Chao , Wan Xin
Published: June 2021

Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe5 and BaMnSb2. Such a system supports chiral surface states in the presence of a strong magnetic field, which exhibit a one-dimensional metal-insulator crossover due to suppression of surface diffusion by disorder potential. We study the nontrivial surface states in a lattice model and find a wide crossover of the level-spacing distribution through a semi-Poisson distribution. We also discover a nonmonotonic evolution of the level statistics due to the disorder-induced mixture of surface and bulk states.
Anisotropic Magnon–Magnon Coupling in Synthetic Antiferromagnets
Authors: He Wei , Xie Z. K. , Sun Rui , Yang Meng , Li Yang , Zhao Xiao-Tian , Liu Wei , Zhang Z. D. , Cai Jian-Wang , Cheng Zhao-Hua , Lu Jie
Published: June 2021

Magnon–magnon coupling in synthetic antiferromagnets advances it as hybrid magnonic systems to explore the quantum information technologies. To induce magnon–magnon coupling, the parity symmetry between two magnetization needs to be broken. Here we experimentally demonstrate a convenient method to break the parity symmetry by the asymmetric structure. We successfully introduce a magnon–magnon coupling in Ir-based synthetic antiferromagnets CoFeB(10 nm)/Ir(t
Ir = 0.6 nm, 1.2 nm)/CoFeB(13 nm). Remarkably, we find that the weakly uniaxial anisotropy field (∼ 20 Oe) makes the magnon–magnon coupling anisotropic. The coupling strength presented by a characteristic anticrossing gap varies in the range between 0.54 GHz and 0.90 GHz for t
Ir = 0.6 nm, and between 0.09 GHz and 1.4 GHz for t
Ir = 1.2 nm. Our results demonstrate a feasible way to induce magnon–magnon coupling by an asymmetric structure and tune the coupling strength by varying the direction of in-plane magnetic field. The magnon–magnon coupling in this highly tunable material system could open exciting perspectives for exploring quantum-mechanical coupling phenomena.
Theoretical investigation of pump–probe photoelectron spectroscopy on KLi
Authors: Hao Man-Hong , Wang Shuo
Published: June 2021

Based on the time-dependent quantum wave packet method, the ionization dynamics of the KLi molecule are theoretically simulated using the pump–probe technique. The Autler–Townes splitting phenomenon of photoelectron spectroscopy is analyzed by changing the laser pulse width, the intensity of the probe laser pulse, and the delay time between the pump and probe pulses. It has been found that the height difference between the splitting peaks becomes larger as the width of the pump pulse increases under the resonant condition. Furthermore, the probe laser with large pulse width has little effect on the peak height difference compared with the pump pulse, but it results in multi-splitting of the photoelectron spectroscopy. Meanwhile, the effect of delay time on the splitting peaks in photoelectron spectroscopy is investigated.
Design of all-solid fluorotellurite fibers with near-zero-flattened dispersion profiles for mid-infrared optical frequency comb generation
Authors: Ma Tianshu , Zhou Ningning , Huang Yali , Jia Zhixu , Qin Weiping , Qin Guanshi
Published: June 2021

All-solid fluorotellurite fibers with near-zero-flattened dispersion profiles in the wavelength range of 1840–2140 nm are designed for mid-infrared optical frequency comb (OFC) generation. The fiber core materials are TeO2-BaF2-Y2O3 (TBY) glasses. The fiber cladding materials are fluoroaluminate and TBY glasses. By controlling the core diameter and the thickness of the thin annular fluoroaluminate or TBY glass, the fiber with the chromatic dispersion value between −0.3 and 0.32 ps nm km−1 in the wavelength range of 1840–2140 nm is achieved. Furthermore, we perform numerical simulations on mid-infrared OFC generation via four-wave mixing in the designed fiber. By using a 1980 nm laser with a pulse width of 1.28 ps and a peak power of 60 W as the pump source, OFC spectrum expanding from 1127 to 4942 nm is obtained in a 2 m long fiber, and the pulse width of the generated OFC is about 25 fs. By varying the repetition rate of the pump source, mid-infrared OFC with tunable mode spacing is generated in the designed fiber.
Total quantum coherence close to the quantum critical points in the XXZ model with Dzyaloshinskii–Moriya interaction
Authors: Liu Cheng-Cheng , Cen Shen-Chuan , Liu Zi-Li , Shi Jia-Dong , Ding Zhi-Yong , He Juan , Wu Tao , Ye Liu
Published: June 2021

In this paper, by using the quantum renormalization-group method, we study the relation between total quantum coherence based on

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norm and quantum phase transition in the XXZ model with Dzyaloshinskii–Moriya (DM) interaction. Our findings reveal a distribution relation of quantum coherence in this model, i.e. the value of the quantum coherence of a three-site block state is equal to the sum of its reduced state coherence, and this characteristic can be generalized to a multipartite system. Meanwhile, because of favoring the alignment of spins, the anisotropy suppresses the quantum coherence; on the other hand, by creating the quantum fluctuations, the DM interaction can effectively enhance the value of quantum coherence. Additionally, after several iterations of the renormalization, quantum coherence of the whole block state can form two saturated values, which are related to two different phases: spin-fluid phase and Néel phase. Furthermore, we discover that the total quantum coherence of the block–block state obeys the nonanalytic and scaling properties with the quantum coherence exponent associated with correlation length.
Efficiency droop in InGaN/GaN-based LEDs with a gradually varying In composition in each InGaN well layer
Authors: Qu Shang-Da , Xu Ming-Sheng , Wang Cheng-Xin , Shi Kai-Ju , Li Rui , Wei Ye-Hui , Xu Xian-Gang , Ji Zi-Wu
Published: June 2021

Temperature-dependent and driving current-dependent electroluminescence spectra of two different InGaN/GaN multiple quantum well structures SA and SB are investigated, with the In composition in each well layer (WL) along the growth direction progressively increasing for SA and progressively decreasing for SB. The results show that SB exhibits an improved efficiency droop compared with SA. This phenomenon can be explained as follows: owing to the difference in growth pattern of the WL between these two samples, the terminal region of the WL in SB contains fewer In atoms than in SA, and therefore the former undergoes less In volatilization than the latter during the waiting period required for warming-up due to the difference in the growth temperature between well and barrier layers. This results in SB having a deeper triangular-shaped potential well in its WL than SA, which strongly confines the carriers to the initial region of the WL to prevent them from leaking to the p-GaN side, thus improving the efficiency droop. Moreover, the improvement in the efficiency droop for SB is also partly attributed to its stronger Coulomb screening effect and carrier localization effect.
Creation of electrospray emitters from a flat polytetrafluoroethylene sheet through the use of laser micro-manufacturing
Authors: Maharaj S , Allegre O , Smith KL
Published: June 2021

Electrospray propulsion is a form of electrostatic propulsion that shows potential for use as a thruster on small satellites. Electrospray emitters traditionally use arrays of capillaries, however, this paper investigates the suitability of manufacturing an emitter by laser drilling holes in sheets of polytetrafluoroethylene (PTFE), also known as Teflon. This is done by examining factors such as the machining time, hole shape and degree of taper in holes drilled through different methods. Experimental work was done to determine the shape of holes drilled in a flat sheet, and a computational model was used to simulate the performance of these drilled holes. These results were used to judge if this would be a valid method to manufacture electrospray thrusters, and how these thrusters would compare to more traditional emitters. Based on these results, it was concluded that a PTFE sheet with a width of 0.81 mm would be sufficient to achieve electrospray at voltages lower than those needed for traditional emitters.
Near infrared integrated photonic switches for portable quantum sensors
Authors: Saleeb-Mousa Bruce , Moss James L. , Maclean Jessica O. , Richard P. Campion , Mellor Christopher J.
Published: June 2021

A novel integrated semiconductor photonic switch, based on carrier-induced refractive index changes, has been designed and fabricated for use at near infrared wavelengths (890-920 nm, 750-780 nm and 745-775 nm). These switches are intended for use in quantum sensors which rely on the spectroscopy of caesium, rubidium or potassium atoms respectively. The beam-steering properties of the 890-920 nm device are presented and its extinction ratio measured to be 13.4 dB. This measurement was limited by coupling efficiency. Subsequent changes made to the testing equipment include the implementation of an automated testing routine. This new experimental setup will facilitate the full characterisation of the 890-920 nm device and the newly fabricated optical switches, designed for operation in the wavelength ranges 750-780 nm and 745-775 nm respectively.
Repurposable Hardware in Smart Photonic Components
Authors: Anderson Mike , Philips Ian , Callan Paul , Forysiak Wladek
Published: June 2021

Key to the development of cost effective integrated components is low cost, low power circuitry capable of being repurposed from providing manufacturing based functions, such as characterisation and calibration, to operational control functions. Although these individual functions are well known, efficient and low cost implementations are required to enable competitive module pricing. In the case of an optical Mach Zehnder Modulator (MZM), bias currents require complex control functions, for example based around digitally synthesized sinusoidal pilot tones and harmonic detection via filters [1][2].

Control methods making use of calibrated laboratory equipment have been proposed [2], whereas here we consider the practical adoption of these methods with low cost and low power components which could be readily integrated into an optical module. In particular we investigate the behaviour and capabilities required for automatic digital bias control functionality implemented in a small gate count, low cost Field Programmable Gate Array (FPGA) when used in conjunction with a MZM. We assess the suitability of highly efficient implementations of DSP functions within the bias controller, such as digital filters, for example investigating the use of a computationally efficient algorithm for computing a single component of a discrete Fourier transform [3], and demonstrate the viability of using low cost digital hardware to implement a circuit capable of monitoring the MZM transfer function.

The concept of creating cost effective, repurposable hardware is crucial for implementation and inclusion in optical devices deployed in communications networks and beyond.
Effect of Micron-scale Photoluminescence Variation on Droop Measurements in InGaN/GaN Quantum Wells
Authors: Barrett R M , Ahumada-Lazo R , Alanis J A , Parkinson P , Church S A , Kappers M J , Oliver R A , Binks D J
Published: June 2021

Micro-photoluminescence maps reveal micron-scale spatial variation in intensity, peak emission energy and bandwidth across InGaN/GaN quantum wells. To investigate the effect of this spatial variation on measurements of the dependence of emission efficiency on carrier density, excitation power-dependent emission was collected from a bright and dark region on each of blue-and green emitting samples. The onset of efficiency droop was found to occur at a greater carrier density in the dark regions than in the bright, by factors of 1.2 and 1.8 in the blue and green-emitting samples, respectively. By spatially integrating the emission from progressively larger areas, it is also shown that collection areas greater than ∼50 μm in diameter are required to reduce the intensity variation to less than 10%.
Scattering and absorption coefficients measurements in silicone polymers used in fiber optics
Authors: Ismagilova R I , Shaidullin R I , Khramov I O , Kovalenko N A , Ryabushkin A
Published: June 2021

Scattering and absorption coefficients of organosilicon polymers (polysiloxanes) used in fiber optics were investigated. For this purpose a new measurement technique based on relocatable integrating spheres was implemented. A computer mathematical model of light propagation in a scattering medium was created based on the Monte Carlo method. The experimental results were approximated using this model in order to obtain absorption and scatterring characteristics of different polymer samples.
Understanding femtosecond optical tweezers: the critical role of nonlinear interactions
Authors: Goswami Debabrata
Published: June 2021

Typical single-beam optical tweezers use continuous wave (CW) lasers, which can be explained through force balancing the light pressure from a tightly focused laser beam used for trapping microscopic particles. Recent years have also seen a surge in single-beam optical trapping research with high-repetition-rate femtosecond lasers that has shown certain differences from the CW tweezers, one of which is its sensitive detection capability of the ultrashort pulse induced background free two-photon fluorescence signals. The high peak power of each laser pulse is enough to provide instantaneous trapping potential, while the high repetition rate ensures sustained stable trapping from the successive pulses. Though the capability and usefulness of the optical-tweezers are well established, for both CW and pulsed lasers, simulating real-time scenarios to predict optical trapping behaviour remains a challenging problem. This is especially true for femtosecond laser tweezers since high peak powers are involved when the laser is tightly focused for achieving the tweezing action. The nonlinear optical effect and thermal nonlinearity become much more significant for femtosecond optical trapping. We demonstrate the importance of including these nonlinear interactions for femtosecond pulsed laser mediated optical trapping via their effect in scattering and gradient forces in the Rayleigh regime. Our optical-tweezers model includes thermal and optical nonlinear interactions, making it easier to predict the optical-trap stability in real optical trapping scenarios for both CW and pulsed lasers. Our model provides predictive metrics for choosing solvents, probes, and several optical parameters, which can be validated from our experiments.
Non-Isolated Converters for Low Temperature Plasma
Authors: Hakki A , Kashapov N
Published: June 2021

The paper describes non-isolated converters for plasma torches. A high frequency was used in order to drive the pulse width modulation circuit. The average output current consumption (AOCC) was modified from (1A) up to (2A). The (AOCC) was increased from (1A) up to (2A) by increasing the duty ratio from (0.75) up to (0.88). The switching frequency of the non-isolated inverter was fixed at (18KHz), The maximum output power was (220W), The maximum efficiency of the designed converter was (0.90).
Characteristics and properties of nanolayer hafnium based PVD coatings
Authors: Mironov M M , Grebenshchikova M M , Mironova E A
Published: June 2021

The paper presents an experimental study of the characteristics of a multilayer coating made of titanium and hafnium nitrides. The thickness of layers formed by the ion-plasma coating method was calculated. It was found that the biologically active coating based on titanium nitride and hafnium has a layered structure. The calculated layer thickness is in the range from 6 to 10 nm, the determined thickness is in the range from 10 to 20 nm. The topography of the coating surface contains intergranular boundaries that are reproduced as empty slits with a size of less than 5 nm. The transverse dimensions of the crystals can be estimated at 5-30 nm.
Study of layered system Fe3Sn2-a-Fe(Sn) obtained by ion-plasma sputtering and thermal annealing
Authors: Zhubaev A K , Yerezhepova S K , Karassayeva A A , Kantarbay Ye A
Published: June 2021

Thin Armco Iron foils with a Tin coating deposited by ion-plasma sputtering and subjected to isothermal annealing at 650°C have been studied by Mössbauer spectroscopy. The formation of intermetallic compounds FeSn and Fe 3Sn 2, as well as a solid solution of Tin atoms in a-Fe(Sn), was revealed. The possibility of obtaining a thermally stable layered spatially inhomogeneous Fe 3Sn 2-a-Fe(Sn) system is shown.