This study attempted to eradicate Apple stem pitting virus (ASPV) and Apple stem grooving virus (ASGV) from virus‐infected in vitro shoots of apple rootstocks ‘M9’ and ‘M26’ using shoot tip culture ...and cryopreservation. In shoot tip culture, shoot tips (0.2 mm in length) containing two leaf primordia failed to show shoot regrowth. Although shoot regrowth rate was the highest in the largest shoot tips (1.0 mm in length) containing four leaf primordia, none of the regenerated shoots was virus‐free. Shoot tips (0.5 mm in length) containing two and three leaf primordia produced 100% and 10% of ASPV‐free shoots, respectively, while those (1.0 mm) containing four leaf primordia were not able to eradicate ASPV. ASGV could not be eradicated by shoot tip culture, regardless of the size of the shoot tips tested. In cryopreservation, shoot tips (0.5 mm in length) containing two leaf primordia did not resume shoot growth. Although 1.0‐mm and 1.5‐mm shoot tips gave similarly high ASPV‐free frequencies, the latter had much higher shoot regrowth rate than the former. Very similar results of shoot regrowth and virus eradication by shoot tip culture and cryopreservation were observed in both ‘M9’ and ‘M26’. Histological observations showed that only cells in upper part of apical dome and in leaf primordia 1–3 survived, while other cells were damaged or killed, in shoot tips following cryopreservation. Virus immunolocalization found ASPV was not detected in upper part of apical dome and leaf primordia 1 and 2, but was present in lower part of apical dome, and in leaf primordium 4 and more developed tissues in all samples tested. ASPV was also detected in leaf primordium 3 in about 16.7% and 13.3% samples tested in ‘M9’ and ‘M26’. ASGV was observed in apical dome and leaf primordia 1–6, leaving only a few top layers of cells in apical dome free of the virus. Different abilities of ASPV and ASGV to invade leaf petioles and shoot tips were also noted.
The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A ...hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.
We report a successful observation of pressure-induced superconductivity in a topological compound Bi 2 Te 3 with T c of ∼3 K between 3 to 6 GPa. The combined high-pressure structure investigations ...with synchrotron radiation indicated that the superconductivity occurred at the ambient phase without crystal structure phase transition. The Hall effects measurements indicated the hole-type carrier in the pressure-induced superconducting Bi 2 Te 3 single crystal. Consequently, the first-principles calculations based on the structural data obtained by the Rietveld refinement of X-ray diffraction patterns at high pressure showed that the electronic structure under pressure remained topologically nontrivial. The results suggested that topological superconductivity can be realized in Bi 2 Te 3 due to the proximity effect between superconducting bulk states and Dirac-type surface states. We also discuss the possibility that the bulk state could be a topological superconductor.
The black hole X-ray binary source 4U 1543–47 experienced a super-Eddington outburst in 2021, reaching a peak flux of up to ∼1.96 × 10
−7
erg cm
−2
s
−1
(∼8.2 Crab) in the 2−10 keV band. Soon after ...the outburst began, it rapidly transitioned into the soft state. Our goal is to understand how the accretion disk structure deviates from a standard thin disk when the accretion rate is near Eddington. To do so, we analyzed spectra obtained from quasi-simultaneous observations conducted by the Hard X-ray Modulation Telescope (Insight-HXMT), the Nuclear Spectroscopic Telescope Array (
NuSTAR
), and the
Neil Gehrels Swift
Observatory (
Swift
). These spectra are well fitted by a model comprising a disk, a weak corona, and a reflection component. We suggest that the reflection component is caused by disk self-irradiation, that is by photons emitted from the inner disk that return to the accretion disk surface as their trajectories are bent by the strong gravity field. In this scenario, the best-fitting parameters imply that the reflected flux represents more than half of the total flux. Using general relativistic ray-tracing simulations, we show that this scenario is viable when the disk becomes geometrically thick, with a funnel-like shape, as the accretion rate is near or above the Eddington limit. In the specific case of 4U 1543–47, an angle ≳45 deg between the disk surface and the equatorial plane can explain the required amount of self-irradiation.
ABSTRACT
The observation of the transient sky through a multitude of astrophysical messengers has led to several scientific breakthroughs in the last two decades, thanks to the fast evolution of the ...observational techniques and strategies employed by the astronomers. Now, it requires to be able to coordinate multiwavelength and multimessenger follow-up campaigns with instruments both in space and on ground jointly capable of scanning a large fraction of the sky with a high-imaging cadency and duty cycle. In the optical domain, the key challenge of the wide field-of-view telescopes covering tens to hundreds of square degrees is to deal with the detection, identification, and classification of hundreds to thousands of optical transient (OT) candidates every night in a reasonable amount of time. In the last decade, new automated tools based on machine learning approaches have been developed to perform those tasks with a low computing time and a high classification efficiency. In this paper, we present an efficient classification method using convolutional neural networks (CNNs) to discard many common types of bogus falsely detected in astrophysical images in the optical domain. We designed this tool to improve the performances of the OT detection pipeline of the Ground Wide field Angle Cameras (GWAC) telescopes, a network of robotic telescopes aiming at monitoring the OT sky down to R = 16 with a 15 s imaging cadency. We applied our trained CNN classifier on a sample of 1472 GWAC OT candidates detected by the real-time detection pipeline.
Abstract
Objectives
To compare the short-term outcomes of unilateral biportal endoscopic lumbar interbody fusion (BLIF) and uniportal endoscopic lumbar interbody fusion (ULIF).
Methods
Sixty patients ...diagnosed with L4/5 spinal stenosis who underwent BLIF and ULIF were included (30 in each group). Clinical evaluation was performed preoperatively and postoperatively in the 1st week, 1st month, and 1st year. Factors such as the visual analogue score (VAS), Oswestry Disability Index (ODI), operative time, surgical complications, and radiological outcomes (fusion rate, screw loosening, and cage subsidence) were compared between the two groups.
Results
All patients showed improved mean VAS and ODI at all three postoperative follow-ups, and no statistically significant differences were detected between the BLIF and ULIF groups. The mean operative time in the BLIF group was shorter than that in the ULIF group. Nerve root injury occurred in two patients in the BLIF group, while leakage of cerebrospinal fluid occurred in one patient in the ULIF group. All adverse events were treated adequately prior to discharge. The fusion rates with definite and probable grades were significantly higher in the BLIF group than that in the ULIF group. One case of cage subsidence with no screw loosening occurred in each group.
Conclusion
Both BLIF and ULIF are safe and effective surgical techniques. Compared with ULIF, BLIF has the advantages of shorter operative time and a higher fusion rate. Other merits of BLIF include a wider surgical field, greater maneuverability of instruments, visibility during cage implantation, and transverse orientation of the cage.
Production and maintenance of virus‐free planting materials is pivotal for the control of viral diseases. The present study attempted to test exogenous application of melatonin for eradication of ...apple stem grooving virus (ASGV) from virus‐infected in vitro shoots of apple cultivar Gala. Exogenous application of 15 μm melatonin to the shoot proliferation medium significantly increased the number of shoots and shoot length. The level of endogenous indole‐3‐acetic acid (IAA) was the highest in the shoots proliferating on the shoot proliferation medium containing 15 μm melatonin. Shoot regrowth levels were significantly higher in shoot tips of the virus‐infected shoots cultured for 4 weeks on this medium than the control. In addition, culture of shoot tips of the virus‐infected in vitro shoots proliferated for 4 weeks on this medium resulted in 95% of shoots being virus‐free, while no virus‐free shoots were obtained in shoot tips of the virus‐infected shoots cultured without melatonin. Analyses by microtissue direct RT‐PCR and RT‐qPCR showed that ASGV concentration decreased in shoot tips of the virus‐infected shoots proliferating on the medium containing 15 μm melatonin for 4 weeks. Virus localization showed that exogenous application of melatonin enlarged the virus‐free area in the virus‐infected shoot tips. These data provide explanations as to why exogenous application of melatonin can efficiently eradicate ASGV. Exogenous application of melatonin provides an alternative means for plant virus eradication and has the potential to produce virus‐free plants.
In a prototypical ferromagnet (Ga,Mn)As based on a III-V semiconductor, substitution of divalent Mn atoms into trivalent Ga sites leads to severely limited chemical solubility and metastable ...specimens available only as thin films. The doping of hole carriers via (Ga,Mn) substitution also prohibits electron doping. To overcome these difficulties, Masek et al. theoretically proposed systems based on a I-II-V semiconductor LiZnAs, where isovalent (Zn,Mn) substitution is decoupled from carrier doping with excess/deficient Li concentrations. Here we show successful synthesis of Li(1+y)(Zn(1-x)Mn(x))As in bulk materials. Ferromagnetism with a critical temperature of up to 50 K is observed in nominally Li-excess (y=0.05-0.2) compounds with Mn concentrations of x=0.02-0.15, which have p-type metallic carriers. This is presumably due to excess Li in substitutional Zn sites. Semiconducting LiZnAs, ferromagnetic Li(Zn,Mn)As, antiferromagnetic LiMnAs, and superconducting LiFeAs systems share square lattice As layers, which may enable development of novel junction devices in the future.
Display omitted
Transition metal oxides show great potential as electrocatalysts, owing to the low cost and rich chemical states. However, the limited surface areas, low intrinsic activity and poor ...hydrogen evolution reaction (HER) activity greatly restrict the application for overall water splitting. Herein, we have constructed S doped NiCo2O4 nanosheet arrays by Ar plasma (Ar-NiCo2O4|S) to enhance active sites and boost catalytic kinetics. Consequently, the Ar-NiCo2O4|S shows the improved performances for HER and oxygen evolution reaction (OER). Further, as bifunctional electrocatalysts, Ar-NiCo2O4|S exhibit a voltage of 1.63 V at 10 mA cm−2, as well as good stability.
► Air source heat pump (ASHP) primarily bears two typical mal-defrost phenomena. ► Characteristics of ASHP under these mal-defrost phenomena are investigated. ► The first mal-defrost phenomenon leads ...to decrease of heating capacity and COP. ► The second mal-defrost phenomenon leads to decrease of the heating efficiency. ► Efforts need to be conducted to avoid these mal-defrost phenomena.
A study is presented on the characteristics of the air source heat pump (ASHP) under two kinds of typical mal-defrost phenomena. The definition of the “Mal-defrost phenomena” is put forward, and the possible origins of their occurrence are analyzed. It is concluded that the current defrost strategies may cause mal-defrost phenomena due to the lack of the direct control information, frost thickness. Transient characteristics of the tested ASHP under these mal-defrost phenomena are investigated by field tests. Instant frosting images are captured to record the dynamic frosting process. In the first phenomenon of mal-defrost, the defrost control is carried out over an hour after a “critical” level of frosting has been reached. It reduces the COP and heating capacity by about 17.4% and 29%, respectively. In the second phenomenon of mal-defrost, three defrost operations occur while almost no frost is observed on the heat exchanger during 6
h testing period. It causes 4.2% decrease for the heating efficiency.
PDF
