Scaling of the Fano Effect of the In-Plane Fe-As Phonon and the Superconducting Critical Temperature in Ba_{1-x}K_{x}Fe_{2}As_{2}.

By means of infrared spectroscopy, we determine the temperature-doping phase diagram of the Fano effect for the in-plane Fe-As stretching mode in Ba_{1-x}K_{x}Fe_{2}As_{2}. The Fano parameter 1/q^{2}, which is a measure of the phonon coupling to the electronic particle-hole continuum, shows a remarkable sensitivity to the magnetic and structural orderings at low temperatures. Most strikingly, at elevated temperatures in the paramagnetic tetragonal state we observe a linear correlation between 1/q^{2} and the superconducting critical temperature T_{c}. Based on theoretical calculations and symmetry considerations, we identify the relevant interband transitions that are coupled to the Fe-As mode. In particular, we show that a sizable xy orbital component at the Fermi level is fundamental for the Fano effect and, thus, possibly also for the superconducting pairing.

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.

[Efficacy for artery chemoembolization combined with radiofrequency ablation in the treatment of advanced non-small cell lung cancer].

OBJECTIVE: To investigate efficacy and safety of artery chemoembolization combined with radiofrequency ablation for advanced non-small cell lung cancer. METHODS: A total of 138 cases of Sichuan Cancer Hospital of patients with advanced non-small cell lung cancer were retrospectively analyzed from January 2011 to November 2014.All cases were divided into three groups, 61 cases were treated by artery chemoembolization (ACB group), 43 cases were treated by artery chemoembolization combined with radiofrequency ablation (Joint group), 34 cases were treated by radiofrequency ablation (RFA group). Recent efficiency, overall survival time, adverse reactions and complications of three groups were analyzed. The risk factors related to survival time of 138 patients were analyzed. RESULTS: The recent efficiency of ACB group, Joint group and RFA group were 73.8%(45/61), 93.0%(40/43), 85.3%(29/34), respectively, and the difference was statistically significant (χ(2)=18.499, P=0.005). 1, 2, 3-year survival rates of Joint group were 90.7%(39/43), 58.1%(25/43), 20.9%(9/43), respectively that were better than ACB group(57.4%(35/61), 24.6%(15/61), 11.5%(7/61)) and RFA group(58.8%(20/34), 32.4%(11/34), 11.8%(4/34)), (χ(2) value were respectively 8.242 and 4.934, P values were 0.004 and 0.026). Chemotherapy side effects and complications of ablation were of no significant difference (P>0.05). Chemotherapy side effects and complications of ablation were of no significant difference (P>0.05). The number of tumors, tumor size, TNM staging, eastern cooperative oncology group (ECOG) score were independent risk factors which impact on survival time for non-small cell lung cancer. The artery chemoembolization combined with radiofrequency ablation treatment can improve survival time of patients with advanced non-small cell lung cancer. CONCLUSION: Artery chemoembolization combined with radiofrequency ablation is a safe, effective, minimally-invasive treatment for advanced non-small cell lung cancer.

Hidden T-linear scattering rate in Ba0.6K0.4Fe2As2 revealed by optical spectroscopy.

The optical properties of Ba0.6K0.4Fe2As2 have been determined in the normal state for a number of temperatures over a wide frequency range. Two Drude terms, representing two groups of carriers with different scattering rates (1/τ), well describe the real part of the optical conductivity σ1(ω). A "broad" Drude component results in an incoherent background with a T-independent 1/τb, while a "narrow" Drude component reveals a T-linear 1/τn resulting in a resistivity ρn≡1/σ1n(ω→0) also linear in temperature. An arctan(T) low-frequency spectral weight is also strong evidence for a T-linear 1/τ. A comparison to other materials with similar behavior suggests that the T-linear 1/τn and ρn in Ba0.6K0.4Fe2As2 originate from scattering from spin fluctuations and hence that an antiferromagnetic quantum critical point is likely to exist in the superconducting dome.

Measurement of a sign-changing two-gap superconducting phase in electron-doped Ba(Fe(1-x)Co(x))2As2 single crystals using scanning tunneling spectroscopy.

Scanning tunneling spectroscopic studies of Ba(Fe(1-x)Co(x))(2)As(2) (x=0.06, 0.12) single crystals reveal direct evidence for predominantly two-gap superconductivity. These gaps decrease with increasing temperature and vanish above the superconducting transition T(c). The two-gap nature and the slightly doping- and energy-dependent quasiparticle scattering interferences near the wave vectors (±π, 0) and (0, ±π) are consistent with sign-changing s-wave superconductivity. The excess zero-bias conductance and the large gap-to-T(c) ratios suggest dominant unitary impurity scattering.

Contrasting spin dynamics between underdoped and overdoped Ba(Fe1-xCox)2As2.

We report the first NMR investigation of spin dynamics in the overdoped nonsuperconducting regime of Ba(Fe1-xCox)2As2 up to x=0.26. We demonstrate that the absence of interband transitions with large momentum transfer Q{AF} approximately (pi/a,0) between the hole and electron Fermi surfaces results in complete suppression of antiferromagnetic spin fluctuations for x greater than or approximately 0.15. Our experimental results provide direct evidence for a correlation between T{c} and the strength of Q{AF} antiferromagnetic spin fluctuations.

Evaluating impact level of different factors in environmental impact assessment for incinerator plants using GM (1, N) model.

In this study, the impact levels in environmental impact assessment (EIA) reports of 10 incinerator plants were quantified and discussed. The relationship between the quantified impact levels and the plant scale factors of BeiTou, LiZe, BaLi, LuTsao, RenWu, PingTung, SiJhou and HsinChu were constructed, and the impact levels of the GangShan (GS) and YongKong (YK) plants were predicted using grey model GM (1, N). Finally, the effects of plant scale factors on impact levels were evaluated using grey model GM (1, N) too. According to the predicted results of GM, the relative errors of topography/geology/soil, air quality, hydrology/water quality, solid waste, noise, terrestrial fauna/flora, aquatic fauna/flora and traffic in the GS plant were 17%, 14%, 15%, 17%, 75%, 16%, 13%, and 37%, respectively. The relative errors of the same environmental items in the YK plant were 1%, 18%, 10%, 40%, 37%, 3%, 25% and 33%, respectively. According to GM (1, N), design capacity (DC) and heat value (HV) were the plant scale factors that affected the impact levels significantly in each environmental item, and thus were the most significant plant scale factors. GM (1, N) was effective in predicting the environmental impact and analyzing the reasonableness of the impact. If there is an EIA for a new incinerator plant to be reviewed in the future, the official committee of the Taiwan EPA could review the reasonableness of impact levels in EIA reports quickly.

TGFß1 protects myocardium from apoptosis and oxidative damage after ischemia reperfusion.

OBJECTIVE: Myocardial apoptosis is an important pathologic basis of ischemia-reperfusion injury (I/R). Transforming growth factor ß1 (TGFß1) participates in the regulation of oxidative damage and apoptosis. TGFß1 is upregulated in the repair process of I/R injury. It is speculated that TGFß1 over-expression is involved in the endogenous protective mechanism of I/R injury. This study explores the significance of TGFß1 in myocardial cell apoptosis after I/R. MATERIALS AND METHODS: Rat myocardial I/R injury model was established. Left ventricular ejection fraction (LVEF) and Left ventricular fractional shortening (LVFS) were detected by ultrasonic cardiogram. TGFß1 expression in the myocardium was tested. H9C2 cells were cultured under ischemic hypoxic condition for 6 h, and then were treated by reoxygenation for 6 h to simulate I/R model. H9C2 cells were divided into three groups, including I/R+pIRES2-Blank, I/R+pIRES2 TGFß1, and I/R+pIRES2-TGFß1+LY364947. TGFß1 mRNA and protein levels were evaluated. Cell apoptosis and reactive oxygen species (ROS) were determined by flow cytometry. RESULTS: LVEF and LVFS significantly decreased in I/R group compared with Sham group. TGFß1 mRNA and protein expressions in myocardium from I/R group up-regulated than the control. I/R treatment markedly elevated TGFß1 mRNA and protein levels, increased ROS content, and enhanced cell apoptosis in H9C2 cells. Over-expression of TGFß1 significantly weakened ROS production and apoptosis in H9C2 cells after I/R. TGFß receptor inhibitor LY364947 restrained ROS production and apoptosis attenuation in H9C2 cells treated by TGFß. CONCLUSIONS: TGFß1 alleviates myocardial cell apoptosis after I/R. Blocking TGFß1 attenuates the protective effect of TGFß1 on I/R injury.

Electronic structure of a new layered bismuth oxyselenide superconductor: LaO0.5F0.5BiSe2.

LaO(0.5)F(0.5)BiSe(2) is a new layered superconductor discovered recently, which shows the superconducting transition temperature of 3.5 K. With angle-resolved photoemission spectroscopy, we study the electronic structure of LaO(0.5)F(0.5)BiSe(2) comprehensively. Two electron-like bands are located around the X point of the Brillouin zone, and the outer pockets connect with each other and form large Fermi surface around Γ and M. These bands show negligible k(z) dispersion, indicating their two-dimensional nature. Based on the Luttinger theorem, the carrier concentration is about 0.53 e(-) per unit cell, close to its nominal value. Moreover, the photoemission data and the band structure calculations agree very well, and the renormalization factor is nearly 1.0, indicating the electron correlations in this material are rather weak. Our results suggest that LaO(0.5)F(0.5)BiSe(2) is a conventional BCS superconductor without strong electron correlations.

Dynamic competition between spin-density wave order and superconductivity in underdoped Ba(1-x)K(x)Fe2As2.

An intriguing aspect of unconventional superconductivity is that it always appears in the vicinity of other competing phases, whose suppression brings the full emergence of superconductivity. In the iron pnictides, these competing phases are marked by a tetragonal-to-orthorhombic structural transition and a collinear spin-density wave (SDW) transition. There has been macroscopic evidence for competition between these phases and superconductivity as the magnitude of both the orthorhombicity and magnetic moment are suppressed in the superconducting state. Here, using angle-resolved photoemission spectroscopy on detwinned underdoped Ba(1-x)K(x)Fe2As2, we observe a coexistence of both the SDW gap and superconducting gap in the same electronic structure. Furthermore, our data reveal that following the onset of superconductivity, the SDW gap decreases in magnitude and shifts in a direction consistent with a reduction of the orbital anisotropy. This observation provides direct spectroscopic evidence for the dynamic competition between superconductivity and both SDW and electronic nematic orders in these materials.

Observation of possible topological in-gap surface states in the Kondo insulator SmB6 by photoemission.

SmB6, a well-known Kondo insulator, exhibits a transport anomaly at low temperature. This anomaly is usually attributed to states within the hybridization gap. Recent theoretical work and transport measurements suggest that these in-gap states could be ascribed to topological surface states, which would make SmB6 the first realization of topological Kondo insulator. Here by performing angle-resolved photoemission spectroscopy experiments, we directly observe several dispersive states within the hybridization gap of SmB6. These states show negligible kz dependence, which indicates their surface origin. Furthermore, we perform photoemission circular dichroism experiments, which suggest that the in-gap states possess chirality of the orbital angular momentum. These states vanish simultaneously with the hybridization gap at around 150 K. Together, these observations suggest the possible topological origin of the in-gap states.

Fermi surface dichotomy of the superconducting gap and pseudogap in underdoped pnictides.

High-temperature superconductivity in iron-arsenic materials (pnictides) near an antiferromagnetic phase raises the possibility of spin-fluctuation-mediated pairing. However, the interplay between antiferromagnetic fluctuations and superconductivity remains unclear in the underdoped regime, which is closer to the antiferromagnetic phase. Here we report that the superconducting gap of underdoped pnictides scales linearly with the transition temperature, and that a distinct pseudogap coexisting with the superconducting gap develops on underdoping. This pseudogap occurs on Fermi surface sheets connected by the antiferromagnetic wavevector, where the superconducting pairing is stronger as well, suggesting that antiferromagnetic fluctuations drive both the pseudogap and superconductivity. Interestingly, we found that the pseudogap and the spectral lineshape vary with the Fermi surface quasi-nesting conditions in a fashion that shares similarities with the nodal-antinodal dichotomous behaviour observed in underdoped copper oxide superconductors.

Anisotropic structure of the order parameter in FeSe(0.45)Te(0.55) revealed by angle-resolved specific heat.

The central issues for understanding iron (Fe)-based superconductors are the symmetry and structure of the superconducting gap. So far the experimental data and theoretical models have been highly controversial. Some experiments favor two or more constant or nearly constant gaps, others indicate strong anisotropy and yet others suggest gap zeros ('nodes'). A unique method for addressing this issue, and one of very few methods that are bulk and angle resolved, is measuring the electronic-specific heat in a rotating magnetic field. In this study, we present the first such measurement for an Fe-based high-T(c) superconductor. We observed a fourfold oscillation of the specific heat as a function of the in-plane magnetic field direction. Our results are consistent with the expectations for an extended s-wave model, with a significant gap anisotropy on the electron pockets and the gap minima along the ΓM (Fe-Fe bond) direction.

Coexistence of competing orders with two energy gaps in real and momentum space in the high temperature superconductor Bi_{2}Sr_{2-x}La_{x}CuO_{6+delta}.

Through a combined scanning tunneling microscopy and angle-resolved photoemission spectroscopy study, we report the observation of two distinct gaps (a small and a large gap) that coexist both in real space and in the antinodal region of momentum space, below the superconducting transition temperature (T_{c}) of Bi_{2}Sr_{2-x}La_{x}CuO_{6+delta}. We show that the small gap is associated with superconductivity. The large-gap persists above T_{c}, and seems linked to observed charge ordering. We find a strong correlation between the large and small gaps suggesting that they are affected by similar physical processes.

Novel mechanism of a charge density wave in a transition metal dichalcogenide.

The charge density wave (CDW) is usually associated with Fermi surfaces nesting. We here report a new CDW mechanism discovered in a 2H-structured transition metal dichalcogenide, where the two essential ingredients of the CDW are realized in very anomalous ways due to the strong-coupling nature of the electronic structure. Namely, the CDW gap is only partially open, and charge density wave vector match is fulfilled through participation of states of the large Fermi patch, while the straight Fermi surface sections have secondary or negligible contributions.

Large anisotropic normal-state magnetoresistance in clean MgB2 thin films.

We report a large normal-state magnetoresistance with temperature-dependent anisotropy in very clean epitaxial MgB2 thin films (residual resistivity much smaller than 1 microOmega cm) grown by hybrid physical-chemical vapor deposition. The magnetoresistance shows a complex dependence on the orientation of the applied magnetic field, with a large magnetoresistance (Delta(rho)/(rho)0=136%) observed for the field H perpendicular ab plane. The angular dependence changes dramatically as the temperature is increased, and at high temperatures the magnetoresistance maximum changes to H||ab. We attribute the large magnetoresistance and the evolution of its angular dependence with temperature to the multiple bands with different Fermi surface topology in MgB2 and the relative scattering rates of the sigma and pi bands, which vary with temperature due to stronger electron-phonon coupling for the sigma bands.

Macroscopic phase separation in high-temperature superconductors.

High-temperature superconductivity is recovered by introducing extra holes to the Cu-O planes, which initially are insulating with antiferromagnetism. In this paper I present data to show the macroscopic electronic phase separation that is caused by either mobile doping or electronic instability in the overdoped region. My results clearly demonstrate that the electronic inhomogeneity is probably a general feature of high-temperature superconductors.

Late metabolic acidosis in low-birth-weight babies: report of four cases.

Four low-birth-weight babies, though fed an adequate amount of formula, failed to regain their birth weight within ten days. Blood gas studies revealed metabolic acidosis in all. Their body weight gain improved dramatically after adding sodium bicarbonate to the milk. Late metabolic acidosis was presented, even using special premature formula, in three of them.