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The deconfined quantum critical point (DQCP) represents a paradigm shift in quantum matter studies, presenting a “beyond Landau” scenario for order–order transitions. Its experimental realization, however, has remained elusive. Using high-pressure 11 B nuclear magnetic resonance measurements on the quantum magnet SrCu 2 (BO 3 ) 2 , we here demonstrate a magnetic-field induced plaquette-singlet to antiferromagnetic transition above 1.8 GPa at a notably low temperature, T c ≃ 0.07 K. First-order signatures of the transition weaken with increasing pressure, and we observe quantum critical scaling at the highest pressure, 2.4 GPa. Supported by model calculations, we suggest that these observations can be explained by a proximate DQCP inducing critical quantum fluctuations and emergent O(3) symmetry of the order parameters. Our findings offer a concrete experimental platform for the investigation of the DQCP.

Chromobox homologue 7 (CBX7) is a member of the polycomb group family that plays a pivotal role in regulating cellular processes in human cancers. This study aims to explore the function and underlying molecular mechanisms of CBX7 in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). The expression of CBX7 in LUAD and LUSC tissues was analyzed by UALCAN and GEPIA based on the TCGA database. Cell viability and apoptosis were measured by CCK-8 and flow cytometry assays, respectively. Cell migration and invasion were detected by transwell assay. The functions of downregulated genes in LUAD were enriched via GO and KEGG pathway analyses. The mRNA expression of CBX7, ERK1/2, and p38 was determined by qRT-PCR, and the protein levels of CBX7, ERK1/2, p-ERK1/2, p38, and p-p38 were measured by Western blotting. Tumor xenograft model was established to validate the antitumor effect of CBX7. The expression of CBX7 and Ki-67 in tumor tissues was detected by immunohistochemistry. CBX7 was downregulated in the tissues and cells of both LUAD and LUSC. Low CBX7 expression was associated with a poor overall survival rate in LUAD patients. CBX7 overexpression inhibited the viability, migration, and invasion and promoted the apoptosis of LUAD and LUSC cells. In addition, the downregulated genes in LUAD were enriched in MAPK cascade (GO) and MAPK signaling pathway (KEGG). ERK/MAPK pathway was then determined as a downstream target of CBX7, which was inhibited by CBX7 overexpression in LUAD and LUSC cells. The overexpression of CBX7 inhibited the malignant progression of LUAD and LUSC cells probably via suppressing the ERK/MAPK signaling pathway in vitro and in vivo.

The vortex core can be regarded as a nanoscale confined system for quasiparticles in a type-II superconductor. It is very interesting to investigate the interplay between the vortex core and other microscopic quantum confined systems. We observe band-like canals with the width of about 15 nm on the surface of KCa

We performed magnetization measurements in a single crystal of the anisotropic bilayer pnictide superconductor KCa$_2$Fe$_4$As$_4$F$_2$, with $T_c$ $\simeq$ 34 K, for $H$$\parallel$$c$-axis and $H$$\parallel$$ab$-planes. A second magnetization peak (SMP) was observed in the isothermal $M(H)$ curves measured below 16 K for $H$$\parallel$$ab$-planes. A peak in the temperature variation of the critical current density, $J_{c}$($T$), at 16 K, strongly suggests the emergence of Josephson vortices at lower temperatures, which leads to the SMP in the sample. In addition, it is noticed that the appearance of Josephson vortices below 16 K renders easy magnetic flux penetration. A detailed vortex dynamics study suggests that the SMP can be explained in terms of elastic pinning to plastic pinning crossover. Furthermore, contrary to the common understanding, the temperature variation of the first peak field, $H_1$, below and above 16 K, behaves non-monotonically. A highly disordered vortex phase, governed by plastic pinning, has been observed between 17 K and 23 K, within a field region around an extremely large first peak field. Pinning force scaling suggests that the point defects are the dominant source of pinning for $H$ $\parallel$$ab$-planes, whereas, for H $\parallel$$c$-axis, point defects in addition to surface defects are at play. Such disorder contributes to the pinning due to the variation in charge carrier mean free path, $\delta$$l$-pinning. Moreover, the large $J_c$ observed in our study is consistent with the literature, which advocates this material for high magnetic field applications., Comment: 12 pages, 6 figures

We performed magnetization measurements in a single crystal of the anisotropic bilayer pnictide superconductor KCa[Formula: see text]Fe[Formula: see text]As[Formula: see text]F[Formula: see text], with [Formula: see text] [Formula: see text] 34 K, for [Formula: see text] [Formula: see text] [Formula: see text]-axis and [Formula: see text] [Formula: see text] [Formula: see text]-planes. A second magnetization peak (SMP) was observed in the isothermal M(H) curves measured below 16 K for [Formula: see text] [Formula: see text] [Formula: see text]-planes. A peak in the temperature variation of the critical current density, [Formula: see text](T), at 16 K, strongly suggests the emergence of Josephson vortices at lower temperatures, which leads to the SMP in the sample. In addition, it is noticed that the appearance of Josephson vortices below 16 K renders easy magnetic flux penetration. A detailed vortex dynamics study suggests that the SMP can be explained in terms of elastic pinning to plastic pinning crossover. Furthermore, contrary to the common understanding, the temperature variation of the first peak field, [Formula: see text], below and above 16 K, behaves non-monotonically. A highly disordered vortex phase, governed by plastic pinning, has been observed between 17 and 23 K, within a field region around an extremely large first peak field. Pinning force scaling suggests that the point defects are the dominant source of pinning for H [Formula: see text] [Formula: see text]-planes, whereas, for H [Formula: see text] [Formula: see text]-axis, point defects in addition to surface defects are at play. Such disorder contributes to the pinning due to the variation in charge carrier mean free path, [Formula: see text] -pinning. Moreover, the large [Formula: see text] observed in our study is consistent with the literature, which advocates this material for high magnetic field applications.

COVID-19 is a hot issue right now, and it's causing a huge number of infections in people, posing a grave threat to human life. Deep learning-based image diagnostic technology can effectively enhance the deficiencies of the current main detection method. This paper proposes a multi-classification model diagnosis based on segmentation and classification multi-task.In the segmentation task, the end-to-end DRD U-Net model is used to segment the lung lesions to improve the ability of feature reuse and target segmentation. In the classification task, the model combined with WGAN and Deep Neural Network classifier is used to effectively solve the problem of multi-classification of COVID-19 images with small samples, to achieve the goal of effectively distinguishing COVID-19 patients, other pneumonia patients, and normal subjects.Experiments are carried out on common X-ray image and CT image data sets. The results display that in the segmentation task, the model is optimal in the key indicators of DSC and HD, and the error is increased by 0.33% and reduced by 3.57 mm compared with the original network U-Net. In the classification task, compared with SMOTE oversampling method, accuracy increased from 65.32% to 73.84%, F-measure increased from 67.65% to 74.65%, G-mean increased from 66.52% to 74.37%. At the same time, compared with other classical multi-task models, the results also have some advantages.This study provides new possibilities for COVID-19 image diagnosis methods, improves the accuracy of diagnosis, and hopes to provide substantial help for COVID-19 diagnosis.

SummaryThe COVID-19 pandemic and the SARS-CoV-2 with its variants have posed unprecedented challenges worldwide. Existing vaccines have limited effectiveness against the SARS-CoV-2 variants. Therefore, novel vaccines to match current mutated viral lineages with long-term protective immunity are urgently in demand. In the current study, we for the first time designed a recombinant Adeno-Associated Virus 5 (rAAV5)-based vaccine named as rAAV-COVID-19 vaccine (Covacinplus) by using RBD-plus of spike protein with both the single-stranded and the self-complementary AAV5 delivering vectors (ssAAV5 and scAAAV5), which provides excellent protection from SARS-CoV-2 infection. A single dose vaccination induced the strong immune response against SARS-CoV-2. The induced neutralizing antibodies (NAs) titers were maintained at a high peak level of over 1:1024 even after more than one year of injection and accompanied with functional T-cells responses in mice. Importantly, both ssAAV- and scAAV-based RBD-plus vaccines exhibited high levels of serum NAs against current circulating variants including variants Alpha, Beta, Gamma and Delta. SARS-CoV-2 virus challenge test showed that ssAAV5-RBD-plus vaccine protected both young and old age mice from SARS-CoV-2 infection in the upper and the lower respiratory tracts. Moreover, whole genome sequencing demonstrated that AAV vector DNA sequences were not found in the genome of the vaccinated mice after one year vaccination, demonstrating excellent safety of the vaccine. Taken together, this study suggests that rAAV5-based vaccine is powerful against SARS-CoV-2 and its variants with long-term protective immunity and excellent safety, which has great potential for development into prophylactic vaccination in human to end this global pandemic.

Background: A lot of recent researches have focused on the duration of the nature immunity elicited by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. An improved understanding of the immunity offered by the antibodies developed against SARS-CoV-2 in recovered patients is critical for the development of diagnostic tests and vaccines. Methods: We enrolled 114 donors, which providing blood samples after discharge for half a year and one year. Neutralizing antibodies (NAbs) were tested using a micro-neutralization assay. Results: In two tests, 82 of 114 recovered patients completed the first test half a year after discharge and NAbs remained detectable in the vast majority of patients (75/82, 91.46%). In the comparison of the two intervals, 50% (27/54) of individuals had increased NAbs titers. when 31.48% (17/54) of patients remained unchanged. Conclusion: Our results suggest that immune ability is acquired in most individuals infected with SARS-CoV-2 and is sustained in a majority of patients for up to a year after recovery.

We report the observation of discrete bound states with the energy levels deviating from the widely believed ratio of 1∶3∶5 in the vortices of an iron-based superconductor KCa_{2}Fe_{4}As_{4}F_{2} through scanning tunneling microscopy (STM). Meanwhile Friedel oscillations of vortex bound states are also observed for the first time in related vortices. By doing self-consistent calculations of Bogoliubov-de Gennes equations, we find that at extreme quantum limit, the superconducting order parameter exhibits a Friedel-like oscillation, which modifies the energy levels of the vortex bound states and explains why it deviates from the ratio of 1∶3∶5. The observed Friedel oscillations of the bound states can also be roughly interpreted by the theoretical calculations, however some features at high energies could not be explained. We attribute this discrepancy to the high energy bound states with the influence of nearby impurities. Our combined STM measurement and the self-consistent calculations illustrate a generalized feature of vortex bound states in type-II superconductors.

KCa${}_{2}$Fe${}_{4}$As4F${}_{2}$ and its sister compounds provide a new platform to study superconducting mechanism of iron-based superconductors. Using scanning tunneling microscopy/spectroscopy, the authors observe here a full gap feature with a gap value close to 4.6 meV in tunneling spectra measured in KCa${}_{2}$Fe${}_{4}$As4F${}_{2}$. Quasiparticle interference patterns only show the intraband scattering of the holelike $\ensuremath{\alpha}$ pocket. The derived Fermi energy of this band is only about 24 meV, which indicates a deviation from the basic requirement of the weak-coupling BCS theory.

We report the observation of discrete bound states with the energy levels deviating from the widely believed ratio of 1∶3∶5 in the vortices of an iron-based superconductor KCa_{2}Fe_{4}As_{4}F_{2} through scanning tunneling microscopy (STM). Meanwhile Friedel oscillations of vortex bound states are also observed for the first time in related vortices. By doing self-consistent calculations of Bogoliubov-de Gennes equations, we find that at extreme quantum limit, the superconducting order parameter exhibits a Friedel-like oscillation, which modifies the energy levels of the vortex bound states and explains why it deviates from the ratio of 1∶3∶5. The observed Friedel oscillations of the bound states can also be roughly interpreted by the theoretical calculations, however some features at high energies could not be explained. We attribute this discrepancy to the high energy bound states with the influence of nearby impurities. Our combined STM measurement and the self-consistent calculations illustrate a generalized feature of vortex bound states in type-II superconductors.

We report a new design of temperature-modulated dilatometer, which obtains the linear thermal expansion coefficient by measuring the oscillating changes of the sample's length and temperature by a piezobender and a thermocouple, respectively. Using an iron-based superconductor KFe$_2$As$_2$ as an example, we show that this device is able to measure thin samples with high resolutions at low temperatures and high magnetic fields. Despite its incapability of giving absolute values, the new dilatometer provides a high-resolution method to study many important physical properties in condensed matter physics, such as thermal and quantum phase transitions, and vortex dynamics in the superconducting state. The prototype design of this device can be further improved in many aspects to meet particular requirements., Comment: 6 pages, 3 figures; An error has been found in the setup and eta now can be independently determined without normalization to the standard sample

In high temperature cuprate superconductors, the interlayer coupling between the CuO$_2$ planes plays an important role in dictating superconductivity, as indicated by the sensitive dependence of the critical temperature (T$_C$) on the number of CuO$_2$ planes in one structural unit. In Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ superconductor with two CuO$_2$ planes in one structural unit, the interaction between the two CuO$_2$ planes gives rise to band splitting into two Fermi surface sheets (bilayer splitting) that have distinct superconducting gap. The iron based superconductors are composed of stacking of the FeAs/FeSe layers; whether the interlayer coupling can cause similar band splitting and its effect on superconductivity remain unclear. Here we report high resolution laser-based angle-resolved photoemission spectroscopy (ARPES) measurements on a newly discovered iron based superconductor, KCa$_2$Fe$_4$As$_4$F$_2$ (T$_C$=33.5\,K) which consists of stacking FeAs blocks with two FeAs layers separated by insulating Ca$_2$F$_2$ blocks. Bilayer splitting effect is observed for the first time that gives rise to totally five hole-like Fermi surface sheets around the Brilliouin zone center. Band structure calculations reproduce the observed bilayer splitting by identifying interlayer interorbital interaction between the two FeAs layers within one FeAs block. All the hole-like pockets around the zone center exhibit Fermi surface-dependent and nodeless superconducting gap. The gap functions with short-range antiferromagetic fluctuations are proposed and the gap symmetry can be well understood when the interlayer pairing is considered. The particularly strong interlayer pairing is observed for one of the bands. Our observations provide key information on the interlayer coupling and interlayer pairing in understanding superconductivity in iron based superconductors.

We report heat capacity measurements of ${\mathrm{SrCu}}_{2}({\mathrm{BO}}_{3}{)}_{2}$ under high pressure along with simulations of relevant quantum spin models and map out the $(P,T)$ phase diagram of the material. We find a first-order quantum phase transition between the low-pressure quantum dimer paramagnet and a phase with signatures of a plaquette-singlet state below $T=2\text{ }\text{ }\mathrm{K}$. At higher pressures, we observe a transition into a previously unknown antiferromagnetic state below 4 K. Our findings can be explained within the two-dimensional Shastry-Sutherland quantum spin model supplemented by weak interlayer couplings. The possibility to tune ${\mathrm{SrCu}}_{2}({\mathrm{BO}}_{3}{)}_{2}$ between the plaquette-singlet and antiferromagnetic states opens opportunities for experimental tests of quantum field theories and lattice models involving fractionalized excitations, emergent symmetries, and gauge fluctuations.

Magnetically mediated Cooper pairing is generally regarded as a key to establish the unified mechanism of unconventional superconductivity. One crucial evidence is the neutron spin resonance arising in the superconducting state, which is commonly interpreted as a spin-exciton from collective particle-hole excitations confined below the superconducting pair-breaking gap ($2\Delta$). Here, on the basis of inelastic neutron scattering measurements on a quasi-two-dimensional iron-based superconductor KCa$_2$Fe$_4$As$_4$F$_2$, we have discovered a two-dimensional spin resonant mode with downward dispersions, a behavior closely resembling the low branch of the hour-glass-type spin resonance in cuprates. The resonant intensity is predominant by two broad incommensurate peaks near $Q=$(0.5, 0.5) with a sharp energy peak at $E_R=16$ meV. The overall energy dispersion of the mode exceeds the measured maximum total gap $\Delta_{\rm tot}=|\Delta_k|+|\Delta_{k+Q}|$. These experimental results deeply challenge the conventional understanding of the resonance modes as magnetic excitons regardless of underlining pairing symmetry schemes, and it also points out that when the iron-based superconductivity becomes very quasi-two-dimensional, the electronic behaviors are similar to those in cuprates., Comment: 16 pages, 14 figures, including supplementary materials

Sr$_2$CuTeO$_6$ is a square-lattice N��el antiferromagnet with superexchange between first-neighbor $S=1/2$ Cu spins mediated by plaquette centered Te ions. Substituting Te by W, the affected impurity plaquettes have predominantly second-neighbor interactions, thus causing local magnetic frustration. Here we report a study of Sr$_2$CuTe$_{1-x}$W$_x$O$_6$ using neutron diffraction and $��$SR techniques, showing that the N��el order vanishes already at $x = 0.025 \pm 0.005$. We explain this extreme order suppression using a two-dimensional Heisenberg spin model, demonstrating that a W-type impurity induces a deformation of the order parameter that decays with distance as $1/r^2$ at temperature $T=0$. The associated logarithmic singularity leads to loss of order for any $x>0$. Order for small $x>0$ and $T>0$ is induced by weak interplane couplings. In the nonmagnetic phase of Sr$_2$CuTe$_{1-x}$W$_x$O$_6$, the $��$SR relaxation rate exhibits quantum critical scaling with a large dynamic exponent, $z \approx 3$, consistent with a random-singlet state., 6 pages + 6 pages supplemental material

High resolution angle-resolved photoemission spectroscopy (ARPES) measurements are carried out on CaKFe$_4$As$_4$, KCa$_2$Fe$_4$As$_4$F$_2$ and (Ba$_{0.6}$K$_{0.4}$)Fe$_2$As$_2$ superconductors. Clear evidence of band folding between the Brillouin zone center and corners with a ($\pi$,$\pi$) wave vector has been found from the measured Fermi surface and band structures in all the three kinds of superconductors. A dominant $\sqrt{2}\,\times\,\sqrt{2}$ surface reconstruction is observed on the cleaved surface of CaKFe$_4$As$_4$ by scanning tunneling microscopy (STM) measurements. We propose that the commonly observed $\sqrt{2}\,\times\,\sqrt{2}$ reconstruction in the FeAs-based superconductors provides a general scenario to understand the origin of the ($\pi$,$\pi$) band folding. Our observations provide new insights in understanding the electronic structure and superconductivity mechanism in iron-based superconductors., Comment: 15 pages, 4 figures

We report heat capacity measurements of SrCu_{2}(BO_{3})_{2} under high pressure along with simulations of relevant quantum spin models and map out the (P,T) phase diagram of the material. We find a first-order quantum phase transition between the low-pressure quantum dimer paramagnet and a phase with signatures of a plaquette-singlet state below T=2 K. At higher pressures, we observe a transition into a previously unknown antiferromagnetic state below 4 K. Our findings can be explained within the two-dimensional Shastry-Sutherland quantum spin model supplemented by weak interlayer couplings. The possibility to tune SrCu_{2}(BO_{3})_{2} between the plaquette-singlet and antiferromagnetic states opens opportunities for experimental tests of quantum field theories and lattice models involving fractionalized excitations, emergent symmetries, and gauge fluctuations.

We report a 19F nuclear magnetic resonance (NMR) study on single-crystal KCa2Fe4As4F2 (T c ∼ 33.3 K). The 19F NMR spectral shape of KCa2Fe4As4F2 is weakly dependent on temperature and the Knight shift is small, which implies weak coupling between the CaF layer and the FeAs layer. The temperature dependence of 1/19 T 1 shows a hump below T c, however the 1/75 T 1 decreases just below T c, which implies that there are strong in-plane magnetic fluctuations in the CaF layers than in the FeAs layers. This may be caused by the motion of vortices. The absence of the coherence peak suggests unconventional superconductivity in KCa2Fe4As4F2.

We have systematically studied the effects of in-plane uniaxial pressure $p$ on the superconducting transition temperature $T_c$ in many iron-based superconductors. The change of $T_c$ with $p$ is composed of linear and nonlinear components. The latter can be described as a quadratic term plus a much smaller fourth-order term. In contrast to the linear component, the nonlinear $p$ dependence of $T_c$ displays a pronounced in-plane anisotropy, which is similar to the anisotropic response of the resistivity to $p$. As a result, it can be attributed to the coupling between the superconducting and nematic orders, in accordance with the expectations of a phenomenological Landau theory. Our results provide direct evidences for the interplay between nematic fluctuations and superconductivity, which may be a common behavior in iron-based superconductors., 6 pages, 7 figures

The cases of human infections with H10N8 viruses identified in late 2013 and early 2014 in Jiangxi, China, have raised concerns over the origin, prevalence, and development of these viruses in this region. Our long-term influenza surveillance of poultry and migratory birds in southern China in the past 12 years showed that H10 influenza viruses have been introduced from migratory to domestic ducks over several winter seasons at sentinel duck farms at Poyang Lake, where domestic ducks share their water body with overwintering migratory birds. H10 viruses were never detected in terrestrial poultry in our survey areas until August 2013, when they were identified at live-poultry markets in Jiangxi. Since then, we have isolated 124 H10N8 or H10N6 viruses from chickens at local markets, revealing an ongoing outbreak. Phylogenetic analysis of H10 and related viruses showed that the chicken H10N8 viruses were generated through multiple reassortments between H10 and N8 viruses from domestic ducks and the enzootic chicken H9N2 viruses. These chicken reassortant viruses were highly similar to the human isolate, indicating that market chickens were the source of human infection. Recently, the H10 viruses further reassorted, apparently with H5N6 viruses, and generated an H10N6 variant. The emergence and prevalence of H10 viruses in chickens and the occurrence of human infections provide direct evidence of the threat from the current influenza ecosystem in China. IMPORTANCE After the outbreak of avian-origin H7N9 influenza viruses in China, fatal human infections with a novel H10N8 virus were reported. Utilizing data from 12 years of influenza surveillance in southern China, we showed that H10 viruses were regularly introduced by migratory ducks to domestic ducks on Poyang Lake, a major aggregative site of migratory birds in Asia. The H10 viruses were maintained and amplified in domestic ducks and then transmitted to chickens and reassorted with enzootic H9N2 viruses, leading to an outbreak and human infections at live-poultry markets. The emergence of the H10N8 virus, following a pathway similar to that of the recent H7N9 virus, highlights the role of domestic ducks and the current influenza ecosystem in China that facilitates influenza viruses moving from their reservoir hosts through the live-poultry system to cause severe consequences for public health.

Cu 2 O loaded nano-BiVO 4 (Cu 2 O/BiVO 4 ) photocatalysts with various weight percents of Cu 2 O were successfully prepared by a facile and effective ultrasonic dispersion method at room temperature. Methylene blue (MB), methyl orange (MO) and phenol in an aqueous solution served as a probe reaction to evaluate the photocatalytic activities of the as-prepared Cu 2 O/BiVO 4 catalysts under the irradiation of visible light. The photocatalytic activity of the Cu 2 O/BiVO 4 catalysts was greatly enhanced, compared with that over commercial Degussa P-25 (TiO 2 ), pure Cu 2 O and BiVO 4 . The remarkably enhanced photocatalytic activities could be mainly attributed to the effective transfer of the photogenerated electrons and holes at the interface of BiVO 4 and Cu 2 O, which reduced the recombination of electron–hole pairs. A transfer process of photogenerated carriers was proposed based on the band structures of BiVO 4 and Cu 2 O. The photocatalytic mechanism of Cu 2 O/BiVO 4 catalysts was discussed.

Carbon-doped nano-ZnSn(OH)6 (C-ZnSn(OH)6) photocatalysts with different weight percents of carbon were successfully synthesized by a facile and economical hydrothermal process at 433 K, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, UV–vis diffuse reflection spectroscopy (UV–vis DRS) and nitrogen physisorption studies. The photocatalytic activity was evaluated on the degradation of organic pollutants under ultraviolet (UV) light illumination. The results showed that compared to commercial P25 and pure ZnSn(OH)6, the photocatalytic performance of 0.58% C-ZnSn(OH)6 was remarkably improved. The photocatalytic conversion ratio of benzene and cyclohexane by 0.58% C-ZnSn(OH)6 was up to 77% and 50.5%, which is about 16.0 and 1.39, 12.3 and 6.39 times higher than that of P25 and pure ZnSn(OH)6, respectively. The 0.58% C-ZnSn(OH)6 catalyst also exhibited high photocatalytic activity toward methyl orange (MO) and phenol in suspended solution. Based on the characterization results and the detection of active species, the enhanced photocatalytic activities of C-ZnSn(OH)6 catalysts were discussed.

Carbon-doped nano-Bi2WO6 photocatalysts with different carbon contents were successfully prepared by a facile hydrothermal method at 433 K, and characterized by XRD, BET, XPS, TEM, HR-TEM, SEM, EDX, photoluminescence (PL) and UV–vis spectroscopy. The photocatalytic activity of C-Bi2WO6 was evaluated from the analysis of the photodegradation of methylene blue (MB). The results show that the C-Bi2WO6 photocatalysts exhibit an orthorhombic Bi2WO6 phase. With the increase of carbon content, the absorption intensity of C-Bi2WO6 samples increases in the 410–650 nm region and the absorption edge has a little shift to long wavelength. Compared with reference C-TiO2 or pure Bi2WO6, 0.47% C-Bi2WO6 shows obviously higher UV and visible light photocatalytic activities. The remarkably enhanced photocatalytic activities can be mainly attributed to the fact that the proper carbon doped into nano-Bi2WO6 increases its BET surface area, enhances the absorption in the 410–650 nm region, improves the separation efficiency of photogenerated electrons and holes, and enhances the formation rate of OH on its surface.

Mo2C loaded nano-anatase TiO2 (Mo2C/TiO2) photocatalysts with various weight percents of Mo2C were successfully prepared by temperature-programmed reaction and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflection spectroscopy (UV–vis DRS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), photoelectrochemical (PEC) and Brunauer–Emmett–Teller (BET) surface area measurements. Photocatalytic degradation of methyl orange (MO) and phenol as well as photocatalytic H2 evolution over Mo2C/TiO2 samples was investigated under UV light irradiation. The results show that the Mo2C/TiO2 photocatalysts exhibit a coexistence of both hexagonal Mo2C and anatase TiO2 phases. The 0.54% Mo2C/TiO2 catalyst not only exhibits higher photocatalytic activity but also presents higher resistance to sulfur poisoning as compared to either pure anatase TiO2 or reference 0.54% Pd/TiO2 catalyst. The remarkably enhanced photocatalytic activity can be mainly attributed to the fact that the Mo2C improves the multiple electron transference to O2, which reduces the recombination of electron–hole pairs. The mechanism of photocatalytic activity enhancement was also investigated.

Pr/In/Nd composite oxides with different Pr/In/Nd ratios were successfully prepared using a simple solid state reaction at 873 K. The composites were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurements, photoluminescence (PL) spectra and UV–vis diffuse reflection spectroscopy (UV–vis DRS). The photocatalytic activity of Pr/In/Nd composite oxides was investigated by the degradation of methyl orange (MO) in an aqueous solution under UV and visible light irradiation. It is found that compared with pure In2O3, the absorption intensity of the Pr/In/Nd composite oxide (Pr/In/Nd=1:8:1) increases in the 200–800 nm light region and the absorption edge has a shift to longer wavelength. In addition, the Pr/In/Nd composite oxide (Pr/In/Nd=1:8:1) shows higher UV and visible light photocatalytic activities than pure In2O3. The remarkably enhanced photocatalytic activities could be mainly attributed to the fact that proper introduction of Pr2O3 and Nd2O5 increased the BET surface area of In2O3, improved the separation efficiency of photogenerated electrons and holes, and enhanced the absorption intensity in 200–800 nm light region. The effect of various radical scavengers on the degradation of MO showed that OH, O2−, h+ and H2O2, especially O2−, jointly dominated the photodegradation process of MO under UV light irradiation.

BiOI/ZnSn(OH)6 composite photocatalysts with different weight percents of BiOI were successfully synthesized by a facile and economical deposition method at 80 °C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, UV–vis diffuse reflection spectroscopy (UV–vis DRS) and Brunauer–Emmett–Teller (BET) surface area measurements. Photocatalytic reforming of ethanol for H2 production and photocatalytic degradation of phenol over BiOI/ZnSn(OH)6 samples were investigated. The results showed that the BiOI/ZnSn(OH)6 photocatalysts exhibited a coexistence of both tetragonal BiOI and cubic perovskite ZnSn(OH)6 phases. With increasing BiOI content, the absorption intensity of BiOI/ZnSn(OH)6 increased in the 280–550 nm region and the absorption edge shifted significantly to longer wavelengths compared with that of pure ZnSn(OH)6. The 19.7% BiOI/ZnSn(OH)6 catalyst exhibited obviously higher photocatalytic activity as compared to either pure ZnSn(OH)6 or BiOI, which could be primarily attributed to the presence of intimate contacts between ZnSn(OH)6 and BiOI resulted in easier charge transfer and more efficient separation of electron–hole pairs. The photocatalytic mechanism of BiOI/ZnSn(OH)6 was discussed.

BiOI sensitized nano-Bi 2 WO 6 photocatalysts with different BiOI contents were successfully synthesized by a facile deposition method at room temperature, and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectra, UV–vis diffuse reflection spectroscopy (UV–vis DRS) and Brunauer–Emmett–Teller (BET) surface area measurements. The photocatalytic activity of BiOI/Bi 2 WO 6 was evaluated by the photo-degradation of Reactive Brilliant Red (X-3B) in suspended solution and toluene in gas phase. It has been shown that the BiOI/Bi 2 WO 6 catalysts exhibit a coexistence of both tetragonal BiOI and orthorhombic Bi 2 WO 6 phases. With increasing BiOI content, the absorption intensity of BiOI/Bi 2 WO 6 catalysts increases in the 380–600 nm region and the absorption edge shifts significantly to longer wavelengths as compared to pure Bi 2 WO 6 . The 13.2% BiOI/Bi 2 WO 6 catalyst exhibits obviously higher UV and visible light photocatalytic activities than commercial P25, pure Bi 2 WO 6 and BiOI, for the photodegradation of toluene and X-3B. The remarkably enhanced photocatalytic activities can be attributed to the fact that the proper BiOI sensitized nano-Bi 2 WO 6 increase its BET surface area, decrease band-gap energy, enhance absorption in the 380–600 nm region and inhibit the recombination of photo-induced carriers.

BiOI-sensitized titanium dioxide (TiO2) photocatalysts were prepared by a deposition method at room temperature and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area measurements. The photocatalytic activities of the catalysts were evaluated for the degradation of methyl orange (MO) solution under UV and visible light irradiation. The effects of catalyst amount, initial pH value, initial concentration of MO, as well as KI amount were investigated. The repeatability of photocatalytic activity of the 1.7% BiOI/TiO2 catalyst was also tested. It is shown that BiOI sensitization enhances the photocatalytic activities of TiO2. With BiOI content increasing, the photocatalytic activities of BiOI/TiO2 under UV and visible light irradiation first increase, reaching a maximum around BiOI content of 1.7%, and then decrease with further increasing BiOI content. The 1.7% BiOI/TiO2 catalyst obviously exhibits much higher visible light photocatalytic activity than P25, and its UV light photocatalytic activity is slightly higher than that of P25. Under the conditions of a catalytic dose of 1.5 g·L−1, initial pH of 3.0, initial MO concentration of 20 mg·L−1, UV power of 300 W, and air flow rate of 0.8 L·min−1, complete degradatio is achieved within 60 min. The repeatability of photocatalytic activity of the 1.7% BiOI/TiO2 catalyst is highly reliable.

A novel H7N9 influenza A virus first detected in March 2013 has since caused more than 130 human infections in China, resulting in 40 deaths. Preliminary analyses suggest that the virus is a reassortant of H7, N9 and H9N2 avian influenza viruses, and carries some amino acids associated with mammalian receptor binding, raising concerns of a new pandemic. However, neither the source populations of the H7N9 outbreak lineage nor the conditions for its genesis are fully known. Using a combination of active surveillance, screening of virus archives, and evolutionary analyses, here we show that H7 viruses probably transferred from domestic duck to chicken populations in China on at least two independent occasions. We show that the H7 viruses subsequently reassorted with enzootic H9N2 viruses to generate the H7N9 outbreak lineage, and a related previously unrecognized H7N7 lineage. The H7N9 outbreak lineage has spread over a large geographic region and is prevalent in chickens at live poultry markets, which are thought to be the immediate source of human infections. Whether the H7N9 outbreak lineage has, or will, become enzootic in China and neighbouring regions requires further investigation. The discovery here of a related H7N7 influenza virus in chickens that has the ability to infect mammals experimentally, suggests that H7 viruses may pose threats beyond the current outbreak. The continuing prevalence of H7 viruses in poultry could lead to the generation of highly pathogenic variants and further sporadic human infections, with a continued risk of the virus acquiring human-to-human transmissibility., link_to_subscribed_fulltext

Please cite this paper as: Pepin et al. (2012) Multiannual patterns of influenza A transmission in Chinese live bird market systems. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750-2659.2012.00354.x. Background Avian influenza viruses (AIV) cause huge economic losses in poultry industries and pose a substantial threat to human health. However, predicting AIV epizootics and emergence in humans is confounded by insufficient empirical data on the ecology and dynamics of AIV in poultry systems. To address this gap, we quantified incidence patterns for 13 hemagglutinin subtypes of AIV using 6 years of surveillance data that were collected from ten different species of poultry and three different types of poultry holdings (contexts) – retail, wholesale, or farms. Methods We collected 42 646 samples in Shantou, China between 2000 and 2006. We screened samples for hemagglutinin subtypes 1–13 of AIV and Avian Paramyxovirus-type-1 (APMV-1) using monospecific antisera in hemagglutination inhibition tests. We analyzed the data to determine seasonality patterns, subtype–host, and subtype–subtype interactions as well as subtype bias in incidence in different contexts. Results H3, H6, H9, and APMV-1 were the most prevalent. No significant seasonality was found when all subtypes were considered together. For most AIV subtypes and APMV-1, there was subtype specificity for host, context, and coinfection partner. H5 showed the most generalized host usage pattern, followed by H9 and H6. Conclusion Subtype-specific patterns because of host, context, and other subtypes suggest that risk assessments that exclude these details are likely inaccurate. Surveillance should include longitudinal sampling of multiple host species in multiple contexts. Quantitative models of control strategies must consider multiple subtypes, hosts, and source contexts to assess the effectiveness of interventions.

To explore the impact of the history of infection by the influenza A virus subtype H1N1 on secondary infection by the influenza A virus subtype H9N2, pigs non-infected and pre-infected with H1N1 were inoculated with H9N2 in parallel to compare nasal shedding and seroconversion patterns. Unlike pigs without a background of H1N1 infection, nasal shedding was not detected in pigs pre-infected with H1N1. Both groups generated antibodies against H9N2. However, levels of H1N1 antibodies in pigs pre-infected with H1N1 increased quickly and dramatically after challenge with H9N2. Cross-reaction was not observed between H1N1 antibodies and H9N2 viruses. These findings suggest that circulation of the H1N1 virus might be a barrier to the introduction and transmission of the avian H9N2 virus, thereby delaying its adaptation in pigs.

The ongoing avian H7N9 influenza outbreaks in China have caused significant human fatal cases and the virus is becoming established in poultry. Mutations with potential to increase mammalian adaptation have occurred in the polymerase basic protein 2 (PB2) and other viral genes. Here we found that dual 627K and 701N mutations could readily occur during transmission of the virus among ferrets via direct physical contact and these mutations conferred higher polymerase activity and improved viral replication in mammalian cells and enhanced virulence in mice. Special attention needs to be paid to patients with such mutations, as these may serve as an indicator of higher virus replication and increased pathogenicity.

Since 2013 the occurrence of human infections by a novel avian H7N9 influenza virus in China has demonstrated the continuing threat posed by zoonotic pathogens. Although the first outbreak wave that was centred on eastern China was seemingly averted, human infections recurred in October 2013 (refs 3-7). It is unclear how the H7N9 virus re-emerged and how it will develop further; potentially it may become a long-term threat to public health. Here we show that H7N9 viruses have spread from eastern to southern China and become persistent in chickens, which has led to the establishment of multiple regionally distinct lineages with different reassortant genotypes. Repeated introductions of viruses from Zhejiang to other provinces and the presence of H7N9 viruses at live poultry markets have fuelled the recurrence of human infections. This rapid expansion of the geographical distribution and genetic diversity of the H7N9 viruses poses a direct challenge to current disease control systems. Our results also suggest that H7N9 viruses have become enzootic in China and may spread beyond the region, following the pattern previously observed with H5N1 and H9N2 influenza viruses.

Avian Flu in Ferrets A recent outbreak of avian H7N9 influenza in humans in eastern China has been closely monitored for any evidence of human-to-human transmission and its potential for sparking a pandemic. Zhu et al. (p. 183 , published online 23 May) examined the behavior of the avian virus in the ferret, a mammalian model for human influenza. The virus was excreted by the ferrets and could be transmitted readily by contact but displayed limited capacity for airborne infectivity. The pathology of H7N9 is similar to H1N1, and it seems that factors other than the intrinsic pathogenicity of the virus contribute to the reported high fatality rate.

An ability to forecast the prevalence of specific subtypes of avian influenza viruses (AIV) in live-bird markets would facilitate greatly the implementation of preventative measures designed to minimize poultry losses and human exposure. The minimum requirement for developing predictive quantitative tools is surveillance data of AIV prevalence sampled frequently over several years. Recently, a 4-year time series of monthly sampling of hemagglutinin subtypes 1–13 in ducks, chickens and quail in live-bird markets in southern China has become available. We used these data to investigate whether a simple statistical model, based solely on historical data (variables such as the number of positive samples in host X of subtype Y time t months ago), could accurately predict prevalence of H5 and H9 subtypes in chickens. We also examined the role of ducks and quail in predicting prevalence in chickens within the market setting because between-species transmission is thought to occur within markets but has not been measured. Our best statistical models performed remarkably well at predicting future prevalence (pseudo-R2 = 0.57 for H9 and 0.49 for H5), especially considering the multi-host, multi-subtype nature of AIVs. We did not find prevalence of H5/H9 in ducks or quail to be predictors of prevalence in chickens within the Chinese markets. Our results suggest surveillance protocols that could enable more accurate and timely predictive statistical models. We also discuss which data should be collected to allow the development of mechanistic models., published_or_final_version

Domestic ducks in southern China act as an important reservoir for influenza viruses and have also facilitated the establishment of multiple H6 influenza virus lineages. To understand the continuing evolution of these established lineages, 297 H6 viruses isolated from domestic ducks during 2006 and 2007 were genetically and antigenically analyzed. Phylogenetic analyses showed that group II duck H6 viruses had replaced the previously predominant group I lineage and extended their geographic distribution from coastal to inland regions. Group II H6 virus showed that the genesis and development of multiple types of deletions in the neuraminidase (NA) stalk region could occur in the influenza viruses from domestic ducks. A gradual replacement of the N2 NA subtype with N6 was observed. Significant antigenic changes occurred within group II H6 viruses so that they became antigenically distinguishable from group I and gene pool viruses. Gene exchange between group II H6 viruses and the established H5N1, H9N2, or H6N1 virus lineages in poultry in the region was very limited. These findings suggest that domestic ducks can facilitate significant genetic and antigenic changes in viruses established in this host and highlight gaps in our knowledge of influenza virus ecology and even the evolutionary behavior of this virus family in its aquatic avian reservoirs. © 2012, American Society for Microbiology., link_to_OA_fulltext