Control of the radiative properties of functional molecules near metals is a key issue in nano-optics, and is particularly important in the fields of energy transfer and light manipulation at the ...nanoscale and the development of plasmonic devices. Despite the various vibronic transitions (S1 (vvariant prime) arrow right S0 (v)) available for frequency tuning of fluorescence, the molecular emissions near metals reported to date have been subject to Kasha's rule, with radiative decay from the lowest excited state (S1 (0)) (refs 6-10). Here, we show resonant hot electroluminescence arising directly from higher vibronic levels of the singlet excited state (S1 (vvariant prime > 0)) for porphyrin molecules confined inside a nanocavity in a scanning tunnelling microscope, by spectrally tuning the frequency of plasmons. We also demonstrate the generation of unexpected upconversion electroluminescence. These observations suggest that the local nanocavity plasmons behave like a strong coherent optical source with tunable energy, and can be used to actively control the radiative channels of molecular emitters by means of intense resonance enhancement of both excitation and emission.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
We report an unusual pressure-induced superconducting state that coexists with an antiferromagnetic ordering of Eu
2+
moments and shows a large upper critical field comparable to the Pauli ...paramagnetic limit in EuTe
2
. In concomitant with the emergence of superconductivity with
T
c
≈ 3–5 K above
P
c
≈ 6 GPa, the antiferromagnetic transition temperature
T
N
(
P
) experiences a quicker rise with the slope increased dramatically from d
T
N
/d
P
= 0.85(14) K/GPa for
P
≤
P
c
to 3.7(2) K/GPa for
P
≥
P
c
. Moreover, the superconducting state can survive in the spin-flop state with a net ferromagnetic component of the Eu
2+
sublattice under moderate magnetic fields
μ
0
H
≥ 2 T. Our findings establish the pressurized EuTe
2
as a rare magnetic superconductor possessing an intimated interplay between magnetism and superconductivity.
A novel austenite-martensite dual-phase steel with a ductility of ~30% and tensile strength over 1.4 GPa was developed. The hard martensite in the dual phase steel was strengthened through ...precipitation strengthening by Cu/NiAl precipitates, forming the maraging phase. The deformation mechanisms of the steel were investigated using in situ neutron diffraction and transmission electron microscopy (TEM). The results indicate that the maraging phase constrains the deformation of soft austenite, forming a strong skeleton frame with the soft austenite involved in the frame. The yield strength was controlled by the deformation of hard maraging phase, leading to the high strength of the steel. The plasticity of the maraging phase was improved through the synchronously deformation and rotation of martensite grains along with the frame-structure effect. During deformation of the maraging phase, the transfer of the dynamic stress and strain from the hard phase to a soft one compels the cooperative deformation of the soft phase together with the hard phase. This deformation contributes further to the ductility through the transformation-induced plasticity (TRIP) effects of the soft austenite. Furthermore, the cooperative deformation and the dynamic stress/strain partitions can effectively suppress the strain localization at the phase interface, retarding the crack initiation.
Display omitted
•A frame-structured dual phase microstructure was developed.•Strengthened martensite forms skeleton frame with the soft austenite involved.•Hard phase with frame effect controls the yielding behavior of the steel.•The cooperative deformation and stress partitions suppress the strain localization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
A sub-array of the Large High Altitude Air Shower Observatory (LHAASO), KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 ...TeV. Even though the detector construction is still underway, half of the KM2A array has been operating stably since the end of 2019. In this paper, we present the KM2A data analysis pipeline and the first observation of the Crab Nebula, a standard candle in very high energy γ-ray astronomy. We detect γ-ray signals from the Crab Nebula in both energy ranges of 10
100 TeV and
100 TeV with high significance, by analyzing the KM2A data of 136 live days between December 2019 and May 2020. With the observations, we test the detector performance, including angular resolution, pointing accuracy and cosmic-ray background rejection power. The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function d
N
/d
E
= (1.13
0.05
0.08
)
10
(
E
/20 TeV)
cm
s
TeV
. It is consistent with previous measurements by other experiments. This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena, such as cosmic PeVatrons, might be discovered.
H5N1 avian influenza virus (AIV) has emerged as a pathogenic entity for a variety of species, including humans, in recent years. Here we report an outbreak among migratory birds on Lake Qinghaihu, ...China, in May and June 2005, in which more than a thousand birds were affected. Pancreatic necrosis and abnormal neurological symptoms were the major clinical features. Sequencing of the complete genomes of four H5N1 AIV strains revealed them to be reassortants related to a peregrine falcon isolate from Hong Kong and to have known highly pathogenic characteristics. Experimental animal infections reproduced typical highly pathogenic AIV infection symptoms and pathology.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Summary
We investigated the secular trends of the incidence and hospitalization cost of hip fracture in Tangshan, China. The incidence of hip fracture and the hospitalization cost were both ...increasing during the observation period.
Introduction
The present study aimed to determine sex-, age-, and fracture type-specific incidence and annual changes in hip fractures in Tangshan, China, between 2007 and 2018.
Methods
We analyzed annual hip fracture incidence using urban hospital data during 2007–2018 and calculated incidence rate/100,000 person years in each age group and sex. We assessed annual changes in incidence among people aged >60 years using linear-by-linear association tests and evaluated hospitalization costs with the Kruskal–Wallis test.
Results
During the study period, we observed an increasing proportion of hip fractures in people >60 years old from 14.2 to 22.79%. Crude hip fracture incidence increased markedly from 140.87 to 306.56/100,000 in women (
p
< 0.01) and from 124.83 to 167.19/100,000 in men (
p
< 0.01) in the age group >60 years. Type-specific analysis indicated significantly increased trends in incidence of cervical and trochanteric fractures among women and cervical fracture among men (
p
< 0.01). In people aged 36–60 years, the trend of hip fracture increased significantly in both sexes. The total and cervical-to-trochanteric ratio in men increased, with significant upward trends (
p
< 0.01). The proportion of cervical fracture was higher than that for trochanteric fracture in women, with stable levels from 2007 to 2018. Hospitalization costs for cervical and trochanteric fractures increased by 51.91% and 53.20%, respectively, during 2011–2018.
Conclusion
Tangshan will have an increasing burden on health care resources attributable to a considerable rise in hip fracture incidence and the older population. Further investigation of risk factors and subsequent implementation of effective measures to prevent hip fracture are needed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Large-scale, highly integrated and low-power-consuming hardware is becoming progressively more important for realizing optical neural networks (ONNs) capable of advanced optical computing. ...Traditional experimental implementations need N
units such as Mach-Zehnder interferometers (MZIs) for an input dimension N to realize typical computing operations (convolutions and matrix multiplication), resulting in limited scalability and consuming excessive power. Here, we propose the integrated diffractive optical network for implementing parallel Fourier transforms, convolution operations and application-specific optical computing using two ultracompact diffractive cells (Fourier transform operation) and only N MZIs. The footprint and energy consumption scales linearly with the input data dimension, instead of the quadratic scaling in the traditional ONN framework. A ~10-fold reduction in both footprint and energy consumption, as well as equal high accuracy with previous MZI-based ONNs was experimentally achieved for computations performed on the MNIST and Fashion-MNIST datasets. The integrated diffractive optical network (IDNN) chip demonstrates a promising avenue towards scalable and low-power-consumption optical computational chips for optical-artificial-intelligence.
Nanometer-thick passive films on metals usually impart remarkable resistance to general corrosion but are susceptible to localized attack in certain aggressive media, leading to material failure with ...pronounced adverse economic and safety consequences. Over the past decades, several classic theories have been proposed and accepted, based on hypotheses and theoretical models, and oftentimes, not sufficiently nor directly corroborated by experimental evidence. Here we show experimental results on the structure of the passive film formed on a FeCr
Ni
single crystal in chloride-free and chloride-containing media. We use aberration-corrected transmission electron microscopy to directly capture the chloride ion accumulation at the metal/film interface, lattice expansion on the metal side, undulations at the interface, and structural inhomogeneity on the film side, most of which had previously been rejected by existing models. This work unmasks, at the atomic scale, the mechanism of chloride-induced passivity breakdown that is known to occur in various metallic materials.
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