Nodeless electron pairing in CsV3Sb5-derived kagome superconductors.

The newly discovered kagome superconductors represent a promising platform for investigating the interplay between band topology, electronic order and lattice geometry1-9. Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive10-17. In particular, consensus on the electron pairing symmetry has not been achieved so far18-20, in part owing to the lack of a momentum-resolved measurement of the superconducting gap structure. Here we report the direct observation of a nodeless, nearly isotropic and orbital-independent superconducting gap in the momentum space of two exemplary CsV3Sb5-derived kagome superconductors-Cs(V0.93Nb0.07)3Sb5 and Cs(V0.86Ta0.14)3Sb5-using ultrahigh-resolution and low-temperature angle-resolved photoemission spectroscopy. Remarkably, such a gap structure is robust to the appearance or absence of charge order in the normal state, tuned by isovalent Nb/Ta substitutions of V. Our comprehensive characterizations of the superconducting gap provide indispensable information on the electron pairing symmetry of kagome superconductors, and advance our understanding of the superconductivity and intertwined electronic orders in quantum materials.

Time-reversal symmetry-breaking charge order in a kagome superconductor.

The kagome lattice1, which is the most prominent structural motif in quantum physics, benefits from inherent non-trivial geometry so that it can host diverse quantum phases, ranging from spin-liquid phases, to topological matter, to intertwined orders2-8 and, most rarely, to unconventional superconductivity6,9. Recently, charge sensitive probes have indicated that the kagome superconductors AV3Sb5 (A = K, Rb, Cs)9-11 exhibit unconventional chiral charge order12-19, which is analogous to the long-sought-after quantum order in the Haldane model20 or Varma model21. However, direct evidence for the time-reversal symmetry breaking of the charge order remains elusive. Here we use muon spin relaxation to probe the kagome charge order and superconductivity in KV3Sb5. We observe a noticeable enhancement of the internal field width sensed by the muon ensemble, which takes place just below the charge ordering temperature and persists into the superconducting state. Notably, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. We further show the multigap nature of superconductivity in KV3Sb5 and that the [Formula: see text] ratio (where Tc is the superconducting transition temperature and λab is the magnetic penetration depth in the kagome plane) is comparable to those of unconventional high-temperature superconductors. Our results point to time-reversal symmetry-breaking charge order intertwining with unconventional superconductivity in the correlated kagome lattice.

[Texture analysis of diffusion-weighted magnetic resonance imaging to identify atypically enhanced small hepatocellular carcinoma and dysplastic nodules under the background of cirrhosis].

Objective: To investigate the value of texture analysis based on diffusion-weighted magnetic resonance imaging (DWI) in the differential diagnosis of atypically enhanced small hepatocellular carcinoma (sHCC) and dysplastic nodules (DNs) in liver cirrhosis. Methods: Data of 59 cases with atypical enhancement and solitary cirrhotic nodule (≤2 cm) confirmed by dynamic contrast enhanced MRI and surgical pathology specimen were analyzed retrospectively. Among them, 37 cases were of atypically enhanced sHCC and 22 cases of DNS. The DWI signal characteristics of the lesions were analyzed to measure the average apparent diffusion coefficient (ADC) value of the lesions, and the ADC ratio of the lesion to the liver parenchyma. MaZda software was used to manually draw the region of interest to extract the texture parameters of DWI lesions. The three sets (combination of Fisher coefficient, classification of error probability combined with average correlation coefficient and interactive information) were used to select the thirty optimal texture parameters. Raw data analysis (RDA), principal component analysis (PCA), linear discriminant analysis (LDA) and non-linear discriminant analysis (NDA) were performed for texture classification. The difference of ADC value and ADC ratio between sHCC and DNS group was compared by independent sample t-test, and χ2 test was used to compare the count data (or rate). ROC curve analysis was used to evaluate the diagnostic efficiency. Results: The sensitivity, specificity and accuracy of DWI high-signal in the identification of atypically enhanced sHCC and DNs were 94.6% (35/37), 68.2% (15/22), and 84.7% (50/59), respectively. The ADC ratio of atypically enhanced sHCC was significantly lower than DNs, and the difference was statistically significant (t = 2.99, P = 0.002). The sensitivity, specificity, and accuracy for the diagnosis of atypically enhanced sHCC were 73.0% (27/37), 72.7% (16/22) and 72.9% (43/59), respectively. The sensitivity, specificity and accuracy of DWI texture analysis in diagnosing atypically enhanced sHCC were 94.6% (35/37), 95.5% (21/22) and 94.9% (56/59).The diagnostic efficiency of DWI texture analysis (AUC = 0.94) was significantly higher than DWI high-signal (AUC = 0.81) and ADC ratio (AUC = 0.72). Conclusion: The texture analysis based on DWI can identify atypically enhanced sHCC and dysplastic nodules under the background of cirrhosis, and its efficacy is better than qualitative and quantitative DWI.

[Clinical analysis of 8 cases with anti-GQ1b antibody syndrome].

Objective: To investigate the clinical characterization, treatment and prognosis of anti-GQ1b antibody syndrome. Methods: The clinical data of 8 patients with positive serum anti-GQ1b antibody from the Department of Neurology of Nanjing Brain Hospital between June 2016 and July 2018 were analyzed retrospectively. Their serums were tested by immunoblotting. Relevant literatures were reviewed to investigate possible pathogenesis. Results: Of the 8 cases, 4 cases were male, 4 cases were female; their age ranged from 16 to 76 (47±21) years old. Seven of them were with acute onset, the time course of the disease ranged from 2 to 15 (7±4) days. Six cases had a history of influenza prior to the onset of the presenting symptoms. In terms of the clinical manifestations of the eight patients, two were affected with Guillain-Barre syndrome (GBS), two with Cavernous sinus syndrome, one with Miller Fisher syndrome, one with both GBS and spinal cord demyelination, one with Bulbar paralysis, and one with chronic inflammatory demyelinating polyneuropathy (CIDP). The anti-GQ1b antibody IgG in serum was positive in 6 patients, two of whom were combined with positive IgG of anti-GD1b antibody in serum. The anti-GQ1b antibody IgM in serum was positive in 1 patient, and the anti-GQ1b antibody IgM and anti-GT1b antibody IgM in cerebrospinal fluid (CSF) were both positive in the other patient. In terms of the treatment, 3 patients (3/8) received vitamin B treatment only, 2 patients (2/8) received steroid plus vitamin B treatment, 2 patients (2/8) received intravenous immunoglobulin (IVIG) plus vitamin B treatment, and 1 patient (1/8) received steroid plus IVIG treatment. During the 8-33 months' follow-up after discharge, 6 patients were significantly improved in their symptoms, one with mild diplopia, one with limbs weakness, numbness and difficulty in walking. The symptoms of one patient (case 3) fluctuated twice and recovered again after treatment. Conclusions: The disease spectrum of anti-GQ1b antibodies syndrome is broad, and main symptom is ophtalmoplegia. Immunotherapy with IVIG and steroid would be beneficial to prognosis.

Signature of spin-phonon coupling driven charge density wave in a kagome magnet.

The intertwining between spin, charge, and lattice degrees of freedom can give rise to unusual macroscopic quantum states, including high-temperature superconductivity and quantum anomalous Hall effects. Recently, a charge density wave (CDW) has been observed in the kagome antiferromagnet FeGe, indicative of possible intertwining physics. An outstanding question is that whether magnetic correlation is fundamental for the spontaneous spatial symmetry breaking orders. Here, utilizing elastic and high-resolution inelastic x-ray scattering, we observe a c-axis superlattice vector that coexists with the 2[Formula: see text]2[Formula: see text]1 CDW vectors in the kagome plane. Most interestingly, between the magnetic and CDW transition temperatures, the phonon dynamical structure factor shows a giant phonon-energy hardening and a substantial phonon linewidth broadening near the c-axis wavevectors, both signaling the spin-phonon coupling. By first principles and model calculations, we show that both the static spin polarization and dynamic spin excitations intertwine with the phonon to drive the spatial symmetry breaking in FeGe.

Tunable unconventional kagome superconductivity in charge ordered RbV3Sb5 and KV3Sb5.

Unconventional superconductors often feature competing orders, small superfluid density, and nodal electronic pairing. While unusual superconductivity has been proposed in the kagome metals AV3Sb5, key spectroscopic evidence has remained elusive. Here we utilize pressure-tuned and ultra-low temperature muon spin spectroscopy to uncover the unconventional nature of superconductivity in RbV3Sb5 and KV3Sb5. At ambient pressure, we observed time-reversal symmetry breaking charge order below [Formula: see text] 110 K in RbV3Sb5 with an additional transition at [Formula: see text] 50 K. Remarkably, the superconducting state displays a nodal energy gap and a reduced superfluid density, which can be attributed to the competition with the charge order. Upon applying pressure, the charge-order transitions are suppressed, the superfluid density increases, and the superconducting state progressively evolves from nodal to nodeless. Once optimal superconductivity is achieved, we find a superconducting pairing state that is not only fully gapped, but also spontaneously breaks time-reversal symmetry. Our results point to unprecedented tunable nodal kagome superconductivity competing with time-reversal symmetry-breaking charge order and offer unique insights into the nature of the pairing state.

Hidden magnetism uncovered in a charge ordered bilayer kagome material ScV6Sn6.

Charge ordered kagome lattices have been demonstrated to be intriguing platforms for studying the intertwining of topology, correlation, and magnetism. The recently discovered charge ordered kagome material ScV6Sn6 does not feature a magnetic groundstate or excitations, thus it is often regarded as a conventional paramagnet. Here, using advanced muon-spin rotation spectroscopy, we uncover an unexpected hidden magnetism of the charge order. We observe an enhancement of the internal field width sensed by the muon ensemble, which takes place within the charge ordered state. More importantly, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. Taken together with the hidden magnetism found in AV3Sb5 (A = K, Rb, Cs) and FeGe kagome systems, our results suggest ubiqitous time-reversal symmetry-breaking in charge ordered kagome lattices.

Local spectroscopic evidence for a nodeless magnetic kagome superconductor CeRu2.

We report muon spin rotation (µSR) experiments on the microscopic properties of superconductivity and magnetism in the kagome superconductor CeRu2withTc≃5 K. From the measurements of the temperature-dependent magnetic penetration depthλ, the superconducting order parameter exhibits nodeless pairing, which fits best to an anisotropics-wave gap symmetry. We further show that theTc/λ-2ratio is comparable to that of unconventional superconductors. Furthermore, the powerful combination of zero-field (ZF)-µSR and high-fieldµSR has been used to uncover magnetic responses across three characteristic temperatures, identified asT1∗≃110 K,T2∗≃65 K, andT3∗≃40 K. Our experiments classify CeRu2as an exceedingly rare nodeless magnetic kagome superconductor.

Discovery of conjoined charge density waves in the kagome superconductor CsV3Sb5.

The electronic instabilities in CsV3Sb5 are believed to originate from the V 3d-electrons on the kagome plane, however the role of Sb 5p-electrons for 3-dimensional orders is largely unexplored. Here, using resonant tender X-ray scattering and high-pressure X-ray scattering, we report a rare realization of conjoined charge density waves (CDWs) in CsV3Sb5, where a 2 × 2 × 1 CDW in the kagome sublattice and a Sb 5p-electron assisted 2 × 2 × 2 CDW coexist. At ambient pressure, we discover a resonant enhancement on Sb L1-edge (2s→5p) at the 2 × 2 × 2 CDW wavevectors. The resonance, however, is absent at the 2 × 2 × 1 CDW wavevectors. Applying hydrostatic pressure, CDW transition temperatures are separated, where the 2 × 2 × 2 CDW emerges 4 K above the 2 × 2 × 1 CDW at 1 GPa. These observations demonstrate that symmetry-breaking phases in CsV3Sb5 go beyond the minimal framework of kagome electronic bands near van Hove filling.

[Epidemic process and influencing factors of hemorrhagic fever with renal syndrome: a review].

Hemorrhagic fever with renal syndrome (HFRS) is a category B infectious disease caused by hantaviruses that cause acute kidney injury and has a high mortality rate, and HFRS control has been given a high priority in China. It has been found that hantavirus types are closely associated with selective host transformation and regional adaption, and continue to evolve in the form of gene recombination. The severity of HFRS varies in hantavirus types. In addition, global environmental changes and alteration of host animal behaviors accelerate Hantavirus genome variations, and large-scale land reclamation and infrastructure building increases the likelihood of human contacts with hosts and disease-transmitting vectors, thereby increasing the risk of HFRS development. This review summarizes the main characteristics and influencing factors pertaining to the epidemic process of HFRS, so as to provide insights into effective prevention and control of this infectious disease.

Fermion-boson many-body interplay in a frustrated kagome paramagnet.

Kagome-nets, appearing in electronic, photonic and cold-atom systems, host frustrated fermionic and bosonic excitations. However, it is rare to find a system to study their fermion-boson many-body interplay. Here we use state-of-the-art scanning tunneling microscopy/spectroscopy to discover unusual electronic coupling to flat-band phonons in a layered kagome paramagnet, CoSn. We image the kagome structure with unprecedented atomic resolution and observe the striking bosonic mode interacting with dispersive kagome electrons near the Fermi surface. At this mode energy, the fermionic quasi-particle dispersion exhibits a pronounced renormalization, signaling a giant coupling to bosons. Through the self-energy analysis, first-principles calculation, and a lattice vibration model, we present evidence that this mode arises from the geometrically frustrated phonon flat-band, which is the lattice bosonic analog of the kagome electron flat-band. Our findings provide the first example of kagome bosonic mode (flat-band phonon) in electronic excitations and its strong interaction with fermionic degrees of freedom in kagome-net materials.

Tunable anomalous Hall conductivity through volume-wise magnetic competition in a topological kagome magnet.

Magnetic topological phases of quantum matter are an emerging frontier in physics and material science. Along these lines, several kagome magnets have appeared as the most promising platforms. Here, we explore magnetic correlations in the kagome magnet Co3Sn2S2. Using muon spin-rotation, we present evidence for competing magnetic orders in the kagome lattice of this compound. Our results show that while the sample exhibits an out-of-plane ferromagnetic ground state, an in-plane antiferromagnetic state appears at temperatures above 90 K, eventually attaining a volume fraction of 80% around 170 K, before reaching a non-magnetic state. Strikingly, the reduction of the anomalous Hall conductivity (AHC) above 90 K linearly follows the disappearance of the volume fraction of the ferromagnetic state. We further show that the competition of these magnetic phases is tunable through applying either an external magnetic field or hydrostatic pressure. Our results taken together suggest the thermal and quantum tuning of Berry curvature induced AHC via external tuning of magnetic order.

Focal atrial tachycardia arising from the right atrial appendage: electrophysiologic and electrocardiographic characteristics and catheter ablation.

BACKGROUND: Focal atrial tachycardia (AT) arising from the crista terminalis, pulmonary veins, para-Hisian region, tricuspid annulus and coronary sinus ostium regions are well described. Less information exists regarding AT arising from the right atrial appendage (RAA). OBJECTIVE: The study was done to characterise the electrocardiographic and electrophysiologic features and radiofrequency ablation (RFA) of focal AT arising from the RAA. METHODS: Six patients of a consecutive series of 250 patients undergoing RFA for focal AT are reported. Mapping was performed during tachycardia or frequent atrial ectopy to identify the earliest activation in the atria. Atrial appendage angiography was performed to identify the origin in the RAA after RFA. RESULTS: All the six (2.4%) patients (four women; mean age 26 +/- 11 years) had tachycardia originating from RAA. The tachycardia demonstrated a characteristic P-wave morphology and endocardial activation pattern. P-wave morphology was upright in I, II, III and aVF, inverted in aVR, inverted or isoelectric in aVL. Lead V1 showed a negative component and lead V4-V6 showed an upright component in all the patients. The earliest endocardial activity occurred at the high right atria in all the patients. The earliest endocardial activation at the successful RFA site occurred 48 +/- 18 ms before the onset of the P wave. RFA was highly successful in all the six patients. Long-term success was achieved in six of the six patients over a mean follow-up of 24 +/- 5 months. CONCLUSIONS: The RAA is an uncommon site of origin for focal AT 2.4%. There is consistent P-wave morphology and endocardial activation associated with this type of AT. Using mapping targeted to anatomic structures achieved a high success rate for ablation. Irrigated-tip catheter may be helpful for patients who had a recurrence.

Electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia arising from superior tricuspid annulus.

OBJECTIVES: This study describes the electrophysiologic and electrocardiographic characteristics of focal atrial tachycardia (AT) arising from superior tricuspid annulus in six (1.9%) patients of a consecutive series of 320 patients. METHODS: Six patients (mean age 42 +/- 22 years) with a mean cycle length of 326 ms of a consecutive series of 320 patients undergoing radiofrequency ablation for focal AT were mapped. RESULTS: During electrophysiologic study, tachycardia could be induced in five patients with programmed atrial extrastimuli while a spontaneous onset and offset with 'warm-up and cool-down' phenomenon was seen in the other patient. During tachycardia, P-wave morphology in Lead I, II, III and aVF was upright in all the six patients. The precordial leads were dominantly negative or isoelectric in V(1)-V(2) and positive in V(5)-V(6) with a transition at V(3) or V(4). Moreover, the tachycardia was sensitive to intravenous administration of adenosine triphosphate in five of six patients. CONCLUSIONS: Radiofrequency ablation was performed successfully in all patients (mean 4.5 +/- 1.2 applications). No recurrence of AT was observed after a mean follow-up of 8 +/- 6 months. Thus, AT arising from superior tricuspid annulus is rare. Radiofrequency ablation of this kind of AT is safe and effective.

Human plague outbreak in two villages, Yunnan Province, China, 2005.

Plague is still a serious public health problem in Asia. On July 5, 2005, a suspected outbreak of human plague in two Chinese villages was reported to Yunnan Institute of Endemic Disease Control and Prevention (YIEDC). Active case finding, laboratory investigation, environmental inspection, and control measures were conducted by provincial and local health authorities. A suspected case was an individual who resided in one of the two villages and developed fever and painful swollen lymph nodes in the groin, axilla, and neck between June 26 and July 11, 2005. Confirmation was by indirect hemagglutination test (IHA) for plague F1 antibody. A confirmed animal plague case was an animal that tested positive for one of the following tests: IIA, reverse indirect hemagglutination, or bacterial culture. There were three confirmed and one suspected case of human plague. Of nine retrieved rats, three were confirmed cases. Most surveyed houses had poor sanitation, and there was a history of dead rats observed in the villages. After control measures were implemented, the rat density and flea index decreased to acceptable levels and no new cases occurred. The cause of this outbreak was likely due to rat die off in the villages, such that rat flea populations migrated to humans under environmentally favorable conditions. The outbreak was controlled after implementing environmental and educational control measures.

[Effects of nicotine on action potentials of guinea pig and rabbit papillary muscles].

The electrophysiological action of nicotine was studied by microelectrode technique on isolated guinea pig and rabbit papillary muscles. Nicotine had no significant effect on RP, APA and Vmax; but its biphasic effect on APD35, APD90 and ERP were observed in different concentrations, ie: high concentration (604 mumols/L) prolonged APD35, APD90 and ERP by 27.3, 26.0 and 26.1% respectively, whereas low concentration (0.6 mumol/L) shortened them by 49.6, 40.0 and 27.6%, respectively. It is suggested that high concentration of nicotine may enhance the calcium influx, but low concentration decrease it.

[Effects of nicotine on automaticity of sinoatrial node in rabbit heart].

The electro-physiological effects of nicotine on sinoatrial node cells in rabbit heart were studied using intracellular microelectrodes. When superfused with nicotine 604.0, 60.4, 6.0 or 0.6 mumol/L the spontaneous rate stopped or decreased for 20 s and then increased, eventually surpassing the control values 50 +/- 13, 45 +/- 12, 23 +/- 10 and 14 +/- 6%, respectively. The inhibitory phase was blocked by atropine and the excitatory phase was eliminated by tubocurarine chloride, hexamethonium bromide or pindolol. These results suggest that the effects observed may be related to cholinergic system and caused by nicotine induced catecholamine release.