Distinct Kondo Screening Behaviors in Heavy Fermion Filled Skutterudites with 4f

CeOs_{4}Sb_{12} (COS) and PrOs_{4}Sb_{12} (POS) are two representative compounds that provide the ideal vantage point to systematically study the physics of multi-f-electron systems. COS with Ce 4f^{1}, and POS with Pr 4f^{2} configurations show distinct properties of Kondo insulating and heavy fermion superconductivity, respectively. We unveiled the underlying microscopic origin by angle-resolved photoemission spectroscopy studies. Their eV-scale band structure matches well, representing the common characters of conduction electrons in ROs_{4}Sb_{12} systems (R=rare earth). However, f electrons interact differently with conduction electrons in COS and POS. Strong hybridization between conduction electrons and f electrons is observed in COS with band dependent hybridization gaps, and the development of a Kondo insulating state is directly revealed. Although the ground state of POS is a singlet, finite but incoherent hybridization exists, which can be explained by the Kondo scattering with the thermally excited triplet crystalline electric field state. Our results help us to understand the intriguing properties in COS and POS, and provide a clean demonstration of the microscopic differences in heavy fermion systems with 4f^{1} and 4f^{2} configurations.

[The diagnostic value of flow cytometry in patients with lymphoma associated hemophagocytic syndrome].

Objective: To evaluate the reliability of flow cytometry (FCM) for diagnosing lymphoma associated hemophagocytic syndrome (LAHS). Method: The clinical data in 57 patients with hemophagocytic lymphohistiocytosis (HLH)were retrospective analyzed at Peking University Shenzhen Hospital from July 2010 to July 2019. All patients were performed bone marrow FCM and bone marrow pathological examination before final diagnoses were made. The golden diagnosis criterion was based on clinical, biochemical and histopathological evidence, which was regarded as the standard to evaluate the sensitivity and specificity of FCM analysis in diagnosing LAHS. Results: Among 57 cases, 36 cases were eventually diagnosed with LAHS, including 15 B-cell lymphoma(14 diffuse large B-cell lymphoma, 1 B-cell lymphoma with reactive T-cell hyperplasia), 13 aggressive NK/T cell lymphoma/leukemia, 2 cases of gamma-delta T-cell lymphoma, 4 angioimmunoblastic T-cell lymphoma, 1 enteropathy-associated peripheral T-cell lymphoma and 1 anaplastic T-cell lymphoma. Lymphoma cells in bone marrow were detected in all patients by FCM except one ENTCL patient. The sensitivity and the specificity of FCM in LASH compared to bone marrow biopsy were 97.2%(P=0.014)and 90.5%(P=0.488) respectively. In the other 21 non-LAHS patients, T cell receptor Vß (TCRVß) rearrangement was detected in 2 patients with Epstein-Barr virus (EBV) associated primary HLH. Conclusions: FCM effectively detects lymphoma cells in bone marrow of lymphoma patients with LHL, suggesting that FCM could be an important indicator for the diagnosis of LAHS. FCM also has the advantage in differentiating LAHS from other HLH.

[A preliminary study on molecular target identification of drugs in individualized treatment of malignant solid tumors in children].

Objective: To explore the role of drug-related molecular target identification in the individualized treatment of malignant solid tumors in children. Methods: The clinical data of 40 patients diagnosed with malignant solid tumors from Beijing Tongren Hospital, Capital Medical University, between June 2017 and March 2019 were retrospectively analyzed. Immunohistochemistry, polymerase chain reaction and sequencing methods were used to determine the expression levels and mutations of tumor drug molecular targets, and to compare the efficiency as well as the incidence of toxic side effects of chemotherapy using anti-tumor drugs with various molecular targets. Results: A total of 4 tumor drug-related targets were identified in 40 tumor tissue samples, namely DNA topoisomerase-ⅡA (TOPOⅡA), ß(3)-tubulin (Tubulinß(3)), DNA topoisomerase-Ⅰ(TOPOⅠ) and dihydrofolate reductase gene polymorphisms [DHFR (C829T)]. The effective rates of platinum-based agents, methotrexate, irinotecan, vinblastine and anthracycline for malignant solid tumors in children were 90.0% (36/40), 85.0% (34/40), 70.0% (28/40), 67.5% (27/40), 62.5% (25/40), respectively. The effective rates of chemotherapy with irinotecan, methotrexate, and vinblastine in mesenchymal tumors were 68.9% (20/29), 62.1% (18/29), 68.9% (20/29), respectively, which were considerably higher than 18.2% (2/11), 36.4% (4/11) and 36.4% (4/11) in non-mesenchymal tumors, with significant differences (χ(2)=5.487, 15.345, 17.278, all P<0.05). The effective rate of chemotherapy of platinum-based drugs for non-mesenchymal tumors was 72.3% (8/11), which was significantly higher than 58.6% (17/29) in mesenchymal tumors, and the difference was statistically significant (χ(2)=11.231, P<0.05). The intensity of toxic side effects in order from high to low was anthracycline > platinum > methotrexate > vinblastine > irinotecan. Conclusion: Tumor drug-related molecular targets and the sensitivity of tumors of different origins to the same anti-tumor drug as well as side effects are predicted, which provides a theoretical and clinical basis for individualized treatment of malignant tumors in children.

Unveiling the Superconducting Mechanism of Ba_{0.51}K_{0.49}BiO_{3}.

The mechanism of high superconducting transition temperatures (T_{c}) in bismuthates remains under debate despite more than 30 years of extensive research. Our angle-resolved photoemission spectroscopy studies on Ba_{0.51}K_{0.49}BiO_{3} reveal an unexpectedly 34% larger bandwidth than in conventional density functional theory calculations. This can be reproduced by calculations that fully account for long-range Coulomb interactions-the first direct demonstration of bandwidth expansion due to the Fock exchange term, a long-accepted and yet uncorroborated fundamental effect in many body physics.Furthermore, we observe an isotropic superconducting gap with 2Δ_{0}/k_{B}T_{c}=3.51±0.05, and strong electron-phonon interactions with a coupling constant λ∼1.3±0.2. These findings solve a long-standing mystery-Ba_{0.51}K_{0.49}BiO_{3} is an extraordinary Bardeen-Cooper-Schrieffer superconductor, where long-range Coulomb interactions expand the bandwidth, enhance electron-phonon coupling, and generate the high T_{c}. Such effects will also be critical for finding new superconductors.

Band Dependent Interlayer f-Electron Hybridization in CeRhIn_{5}.

A key issue in heavy fermion research is how subtle changes in the hybridization between the 4f (5f) and conduction electrons can result in fundamentally different ground states. CeRhIn_{5} stands out as a particularly notable example: when replacing Rh with either Co or Ir, antiferromagnetism gives way to superconductivity. In this photoemission study of CeRhIn_{5}, we demonstrate that the use of resonant angle-resolved photoemission spectroscopy with polarized light allows us to extract detailed information on the 4f crystal field states and details on the 4f and conduction electron hybridization, which together determine the ground state. We directly observe weakly dispersive Kondo resonances of f electrons and identify two of the three Ce 4f_{5/2}^{1} crystal-electric-field levels and band-dependent hybridization, which signals that the hybridization occurs primarily between the Ce 4f states in the CeIn_{3} layer and two more three-dimensional bands composed of the Rh 4d and In 5p orbitals in the RhIn_{2} layer. Our results allow us to connect the properties observed at elevated temperatures with the unusual low-temperature properties of this enigmatic heavy fermion compound.

Highly Anisotropic and Twofold Symmetric Superconducting Gap in Nematically Ordered FeSe_{0.93}S_{0.07}.

FeSe exhibits a novel ground state in which superconductivity coexists with a nematic order in the absence of any long-range magnetic order. Here, we report on an angle-resolved photoemission study on the superconducting gap structure in the nematic state of FeSe_{0.93}S_{0.07}, without the complications caused by Fermi surface reconstruction induced by magnetic order. We find that the superconducting gap shows a pronounced twofold anisotropy around the elliptical hole pocket near Z (0, 0, π), with gap minima at the end points of its major axis, while no detectable gap is observed around Γ (0, 0, 0) and the zone corner (π, π, k_{z}). The large anisotropy and nodal gap distribution demonstrate the substantial effects of the nematicity on the superconductivity and thus put strong constraints on current theories.

Identification of single nucleotide polymorphisms of the signal transducer and activator of transcription 3 gene (STAT3) associated with body measurement and carcass quality traits in beef cattle.

Previous studies have shown that the signal transducer and activator of transcription 3 gene (STAT3) is involved in lipid storage and energy metabolism, suggesting that STAT3 is a potential candidate gene that affects body measurement and carcass quality traits in animals. Therefore, the aim of this study was to identify polymorphisms in bovine STAT3 and to analyze their possible associations with body measurement and carcass quality traits in 493 individuals of 2 native Chinese cattle breeds: Qinchuan (N = 371) and Jiaxian cattle (N = 122). DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were employed to detect STAT3 single nucleotide polymorphisms (SNPs). We found 5 SNPs: 1 in an exon (g.65812G>A: exon 16) and 4 in introns (g.43591G>A: 13 intron, g.67492T>G: 19 intron, g.67519T>C: 19 intron, and g.68964G>A: 20 intron). Both g.65812G>A and g.68964G>A were not in Hardy- Weinberg equilibrium (HWE), whereas individual frequencies of each genotype were consistent with HWE for other SNPs in Qinchuan cattle populations. For the Jiaxian cattle, the genotype distributions of the 4 mutations were in HWE except for g.67519T>C. The results indicate that these SNPs have a significant association with some body measurements and carcass quality traits (P < 0.05 or P < 0.01). Therefore, STAT3 might have potential effects on production traits in beef cattle populations and could be used for marker-assisted selection.

Association of CRTC2 gene polymorphisms with growth and meat quality traits of Qinchuan cattle.

Growth and meat quality traits play important roles in the evaluation of cattle productivity and are influenced by genetic and environmental factors. CRTC2 is a recently discovered gene related to obesity that may influence fat deposition. The aim of the current study was to detect polymorphisms of bovine CRTC2 and explore their relationships to growth and meat quality in Qinchuan cattle. Three single nucleotide polymorphisms (SNPs); g.3001 C>T; g.3034 G>A; and g.3467 T>C, were identified from sequencing results of 422 Qinchuan cattle. The genotypic distributions of both g.3034 G>A and g.3467 T>C mutations were in agreement with Hardy-Weinberg equilibrium, (P < 0.05), while the T3001C mutation was not (P > 0.05), based on χ(2) test analysis. The SNPs g.3001 C>T and g.3034 G>A are missense mutations (Ser/Phe and Ser/Thr respectively). Additionally, SNPs g.3034 G>A and g.3467 T>C showed a medium polymorphism level (0.25 < PIC< 0.50), whereas g.3001 C>T showed a low polymorphism level (PIC < 0.25). These three SNPs were significantly associated with several growth and meat quality traits in the Qinchuan cattle population (P < 0.05 or P < 0.01). Collectively, these results demonstrate that CRTC2 is involved in the regulation of cattle growth and meat quality, and suggest that CRTC2 is a potential candidate gene for marker-assisted selection in future breeding development programs for Qinchuan cattle.

Measurement of an enhanced superconducting phase and a pronounced anisotropy of the energy gap of a strained FeSe single layer in FeSe/Nb:SrTiO3/KTaO3 heterostructures using photoemission spectroscopy.

Single-layer FeSe films with an extremely expanded in-plane lattice constant of 3.99±0.02 Å are fabricated by epitaxially growing FeSe/Nb:SrTiO3/KTaO3 heterostructures and studied by in situ angle-resolved photoemission spectroscopy. Two elliptical electron pockets at the Brillouin zone corner are resolved with negligible hybridization between them, indicating that the symmetry of the low-energy electronic structure remains intact as a freestanding single-layer FeSe, although it is on a substrate. The superconducting gap closes at a record high temperature of 70 K for the iron-based superconductors. Intriguingly, the superconducting gap distribution is anisotropic but nodeless around the electron pockets, with minima at the crossings of the two pockets. Our results place strong constraints on current theories.

MRI and MRI 3-D reconstruction of anatomic characteristics of the cardinal and uterosacral ligaments in uterine prolapsed women.

OBJECTIVE: This study aimed to evaluate the anatomical alterations of the cardinal ligaments (CL) and uterosacral ligaments (USL) in women with uterine prolapse by magnetic resonance imaging (MRI) and MRI three-dimensional reconstruction (3DR). MATERIALS AND METHODS: Forty patients with uterine prolapse and 40 volunteers with normal support underwent thin layer scan MRI. The 3D models were reconstructed with MRI data and 3D software. Origin, inserted end, geometric shape features of the CL and USL, were compared between the two groups, and the correlation in study group between the MRI and surgical dissection were reported. RESULTS: In the study group, trauma was found in the USL in the insertion or origin. The dorsal USL attached to the sacrum in four (10%) patients was quite different from 12 (30%) patients of the control group. There was no significant difference in the inserted end of the USL between the two groups, nor in the origin and inserted end of the CL. In the study group, MRI and MRI 3DR better evaluated the anatomical characteristics of the USL compared to intraoperative detection via laparoscopy. DISCUSSION: The approach using MRI and MRI 3DR can non-invasively detect the anatomic abnormality associated with the USL in uterine prolapsed women and can be a useful preoperative planning tool.

Nodeless superconducting gap in A(x)Fe2Se2 (A=K,Cs) revealed by angle-resolved photoemission spectroscopy.

Pairing symmetry is a fundamental property that characterizes a superconductor. For the iron-based high-temperature superconductors, an s(±)-wave pairing symmetry has received increasing experimental and theoretical support. More specifically, the superconducting order parameter is an isotropic s-wave type around a particular Fermi surface, but it has opposite signs between the hole Fermi surfaces at the zone centre and the electron Fermi surfaces at the zone corners. Here we report the low-energy electronic structure of the newly discovered superconductors, A(x)Fe(2)Se(2) (A=K,Cs) with a superconducting transition temperature (Tc) of about 30 K. We found A(x)Fe(2)Se(2) (A=K,Cs) is the most heavily electron-doped among all iron-based superconductors. Large electron Fermi surfaces are observed around the zone corners, with an almost isotropic superconducting gap of ~10.3 meV, whereas there is no hole Fermi surface near the zone centre, which demonstrates that interband scattering or Fermi surface nesting is not a necessary ingredient for the unconventional superconductivity in iron-based superconductors. Thus, the sign change in the s(±) pairing symmetry driven by the interband scattering as suggested in many weak coupling theories becomes conceptually irrelevant in describing the superconducting state here. A more conventional s-wave pairing is probably a better description.

Strong band renormalization and emergent ferromagnetism induced by electron-antiferromagnetic-magnon coupling.

The interactions between electrons and antiferromagnetic magnons (AFMMs) are important for a large class of correlated materials. For example, they are the most plausible pairing glues in high-temperature superconductors, such as cuprates and iron-based superconductors. However, unlike electron-phonon interactions (EPIs), clear-cut observations regarding how electron-AFMM interactions (EAIs) affect the band structure are still lacking. Consequently, critical information on the EAIs, such as its strength and doping dependence, remains elusive. Here we directly observe that EAIs induce a kink structure in the band dispersion of Ba1-xKxMn2As2, and subsequently unveil several key characteristics of EAIs. We found that the coupling constant of EAIs can be as large as 5.4, and it shows strong doping dependence and temperature dependence, all in stark contrast to the behaviors of EPIs. The colossal renormalization of electron bands by EAIs enhances the density of states at Fermi energy, which is likely driving the emergent ferromagnetic state in Ba1-xKxMn2As2 through a Stoner-like mechanism with mixed itinerant-local character. Our results expand the current knowledge of EAIs, which may facilitate the further understanding of many correlated materials where EAIs play a critical role.

Picoscale structural insight into superconductivity of monolayer FeSe/SrTiO3.

Remarkable enhancement of the superconducting transition temperature (T c) has been observed for monolayer (ML) FeSe films grown on SrTiO3 substrates. The atomic-scale structure of the FeSe/SrTiO3 interface is an important determinant of both the magnetic and interfacial electron-phonon interactions and is a key ingredient to understanding its high-T c superconductivity. We resolve the atomic-scale structure of the FeSe/SrTiO3 interface through a complementary analysis of scanning transmission electron microscopy and in situ surface x-ray diffraction. We find that the interface is more strongly bonded for a particular registration, which leads to a coherently strained ML. We also determine structural parameters, such as the distance between ML FeSe and the oxide, Se─Fe─Se bond angles, layer-resolved distances between Fe─Se, and registry of the FeSe lattice relative to the oxide. This picoscale structure determination provides an explicit structural framework and constraint for theoretical approaches addressing the high-T c mechanism in FeSe/SrTiO3.

Anomalous helimagnetic domain shrinkage due to the weakening of the Dzyaloshinskii-Moriya interaction in CrAs.

CrAs is a well-known helimagnet with the double-helix structure originating from the competition between the Dzyaloshinskii-Moriya interaction (DMI) and antiferromagnetic exchange interaction J. By resonant soft-x-ray scattering, we observe the magnetic peak (0 0 qm) that emerges at the helical transition with TS ≈ 267.5 K. Intriguingly, the helimagnetic domains significantly shrink on cooling below ~255 K, opposite to the conventional thermal effect. The weakening of DMI on cooling is found to play a critical role here. It causes the helical wave vector to vary, ordered spins to rotate, and extra helimagnetic domain boundaries to form at local defects, thus leading to the anomalous shrinkage of helimagnetic domains. Our results indicate that the size of magnetic helical domains can be controlled by tuning DMI in certain helimagnets.

Evidence of cooperative effect on the enhanced superconducting transition temperature at the FeSe/SrTiO3 interface.

At the interface between monolayer FeSe films and SrTiO3 substrates the superconducting transition temperature (Tc) is unexpectedly high, triggering a surge of excitement. The mechanism for the Tc enhancement has been the central question, as it may present a new strategy for seeking out higher Tc materials. To reveal this enigmatic mechanism, by combining advances in high quality interface growth, 16O [Formula: see text] 18O isotope substitution, and extensive data from angle resolved photoemission spectroscopy, we provide striking evidence that the high Tc in FeSe/SrTiO3 is the cooperative effect of the intrinsic pairing mechanism in the FeSe and interactions between the FeSe electrons and SrTiO3 phonons. Furthermore, our results point to the promising prospect that similar cooperation between different Cooper pairing channels may be a general framework to understand and design high-temperature superconductors.

Anomalous correlation effects and unique phase diagram of electron-doped FeSe revealed by photoemission spectroscopy.

FeSe layer-based superconductors exhibit exotic and distinctive properties. The undoped FeSe shows nematicity and superconductivity, while the heavily electron-doped KxFe2-ySe2 and single-layer FeSe/SrTiO3 possess high superconducting transition temperatures that pose theoretical challenges. However, a comprehensive study on the doping dependence of an FeSe layer-based superconductor is still lacking due to the lack of a clean means of doping control. Through angle-resolved photoemission spectroscopy studies on K-dosed thick FeSe films and FeSe0.93S0.07 bulk crystals, here we reveal the internal connections between these two types of FeSe-based superconductors, and obtain superconductivity below ∼ 46 K in an FeSe layer under electron doping without interfacial effects. Moreover, we discover an exotic phase diagram of FeSe with electron doping, including a nematic phase, a superconducting dome, a correlation-driven insulating phase and a metallic phase. Such an anomalous phase diagram unveils the remarkable complexity, and highlights the importance of correlations in FeSe layer-based superconductors.

Toso regulates differentiation and activation of inflammatory dendritic cells during persistence-prone virus infection.

During virus infection and autoimmune disease, inflammatory dendritic cells (iDCs) differentiate from blood monocytes and infiltrate infected tissue. Following acute infection with hepatotropic viruses, iDCs are essential for re-stimulating virus-specific CD8(+) T cells and therefore contribute to virus control. Here we used the lymphocytic choriomeningitis virus (LCMV) model system to identify novel signals, which influence the recruitment and activation of iDCs in the liver. We observed that intrinsic expression of Toso (Faim3, FcµR) influenced the differentiation and activation of iDCs in vivo and DCs in vitro. Lack of iDCs in Toso-deficient (Toso(-/-)) mice reduced CD8(+) T-cell function in the liver and resulted in virus persistence. Furthermore, Toso(-/-) DCs failed to induce autoimmune diabetes in the rat insulin promoter-glycoprotein (RIP-GP) autoimmune diabetes model. In conclusion, we found that Toso has an essential role in the differentiation and maturation of iDCs, a process that is required for the control of persistence-prone virus infection.

Immunohistochemical and histological studies on internal derangement and organic disturbance of temporomandibular joint.

The study examined the articular cartilages of 14 patients who suffered from temporomandibular joint disturbance syndrome (TMJDS) and 3 healthy fresh cadavers by light microscopy and immunofluorescence, and assayed 14 patients' synovial fluids and sera with indirect hemoagglutination. The results showed that there were antibodies to type II collagen in synovial fluids in 5 of 14 patients and there were some immune complexes in cartilage. So, the authors think that there are autoimmune reactions in the articular tissues in TMJDS because of the exposure of some sequestered antigens.

Measurement of thermal expansion coefficient of human teeth.

The coefficient of thermal expansion of specimens from 60 freshly extracted human teeth were measured over the range 10-80 degrees C using a dilatometer. The coefficient increased rapidly above 50 degrees C, but there was no significant variation with tooth age between 10 and 70 years. The average values obtained were 16.96 (SD 3.83) x 10(-6)/degrees C for enamel, 10.59 (SD 2.38) x 10(-6)/degrees C for dentine, 11.90 (SD 4.42) x 10(-6)/degrees C for crowns and 9.44 (SD 0.61) x 10(-6)/degrees C for roots.

Tuning the band structure and superconductivity in single-layer FeSe by interface engineering.

The interface between transition metal compounds provides a rich playground for emergent phenomena. Recently, significantly enhanced superconductivity has been reported for single-layer FeSe on Nb-doped SrTiO3 substrate. Yet it remains mysterious how the interface affects the superconductivity. Here we use in situ angle-resolved photoemission spectroscopy to investigate various FeSe-based heterostructures grown by molecular beam epitaxy, and uncover that electronic correlations and superconducting gap-closing temperature (Tg) are tuned by interfacial effects. Tg up to 75 K is observed in extremely tensile-strained single-layer FeSe on Nb-doped BaTiO3, which sets a record high pairing temperature for both Fe-based superconductor and monolayer-thick films, providing a promising prospect on realizing more cost-effective superconducting device. Moreover, our results exclude the direct correlation between superconductivity and tensile strain or the energy of an interfacial phonon mode, and highlight the critical and non-trivial role of FeSe/oxide interface on the high Tg, which provides new clues for understanding its origin.