Two-Dimensional Superconducting Fluctuations Associated with Charge-Density-Wave Stripes in La_{1.87}Sr_{0.13}Cu_{0.99}Fe_{0.01}O_{4}.

The presence of a small concentration of in-plane Fe dopants in La_{1.87}Sr_{0.13}Cu_{0.99}Fe_{0.01}O_{4} is known to enhance stripelike spin and charge density wave (SDW and CDW) order and suppress the superconducting T_{c}. Here, we show that it also induces highly two-dimensional superconducting correlations that have been argued to be the signatures of a new form of superconducting order, the so-called pair density wave (PDW) order. In addition, using resonant soft x-ray scattering, we find that the two-dimensional superconducting fluctuation is strongly associated with the CDW stripe. In particular, the PDW signature first appears when the correlation length of the CDW stripe grows over eight times the lattice unit (∼8a). These results provide critical conditions for the formation of the PDW order.

Examining the association between serum free fatty acids and blood levels of testosterone.

BACKGROUND: Multiple studies have uncovered the effects that ingested fat has on human blood levels of testosterone. Yet, few reports have discussed the effect of circulating serum free fatty acids (FFAs). The present study aimed to explore the relationship between serum free fatty acids and blood levels of testosterone. METHODS: In total, 5719 adults were pooled from the database of the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2012. Based on multivariable-linear regression models, we employed a total of 30 FFAs to interpret the relationship of FFAs with blood levels of testosterone. Two models with covariate adjustments were designated for further evaluation and analysis. RESULTS: Capric acid [ß = -0.014, 95% confidence interval (CI) = -0.023, -0.004, P = 0.005], myristic acid (ß = -0.001, 95% CI = -0.001, 0.000, P ≤ 0.001), pentadecanoic acid (ß = -0.013, 95% CI = -0.018, -0.008, P ≤ 0.001), margaric acid (ß = -0.011, 95% CI = -0.017, -0.005, P ≤ 0.001) and alpha-linolenic acid (ß = -0.001, 95% CI = -0.002, 0.000, P = 0.004) in the fully adjusted model were significantly negatively correlated with the testosterone level inh obese men. In the fully adjusted model for the female analysis, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, myristoleic acid, oleic acid, nervonic acid and alpha-linolenic acid were found significantly associated with the testosterone level. CONCLUSIONS: Our findings indicate a significant negative correlation between serum FFAs and blood levels of testosterone. Furthermore, we reveal the essentiality of serum FFAs and their potential effects on the reduction of testosterone levels.

Pectoralis muscle area is associated with bone mineral density and lung function in lung transplant candidates.

Loss of bone mineral density and skeletal muscle area are linked in lung transplant patients. This loss is greater in patients with restrictive compared with obstructive lung diseases. INTRODUCTION: Sarcopenia and osteoporosis are associated with aging and chronic illnesses and may be linked in patients with advanced lung disease. Pectoralis muscle index (PMI) quantitated on computed tomography (CT) of the chest can be used to measure skeletal muscle mass. This study aimed to determine the relationship of PMI to clinical parameters including bone mineral density (BMD) in candidates for lung transplantation. METHODS: A retrospective review of transplant candidates at a single center was performed. Demographic, anthropomorphic, and clinical data were recorded. Pectoralis muscle area (PMA) was determined on an axial slice from a chest CT. PMI was calculated as the PMA divided by height squared. BMD was obtained from routine dual-energy X-ray absorptiometry (DXA) scan. RESULTS: In 226 included patients, mean PMI was 8.2 ± 3.0 cm2/m2 in males and 6.1 ± 2.1 cm2/m2 in females. Osteopenia was present in 44.4%, and 23.2% of patients had osteoporosis. Patients with obstructive lung disease had lower body mass index (22.0 ± 4.9 versus 27.9 ± 4.9 kg/m2, p < 0.001), PMI (6.0 ± 2.3 versus 8.2 ± 2.8 cm2/m2, p < 0.001), and BMD (- 2.3 ± 1.1 versus - 1.3 ± 1.1, p < 0.001) compared with patients with restrictive lung disease. PMI was a significant predictor of BMD (ß = 0.16, p < 0.001). CONCLUSION: The association between muscle area and BMD in lung transplant candidates suggests that similar mechanisms may underlie the development of both. Differences in PMI and BMD in patients with obstructive versus restrictive lung disease may result from differences in respiratory physiology or disease processes.

Ideal charge-density-wave order in the high-field state of superconducting YBCO.

The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa2Cu3O2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field ([Formula: see text]) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlation length as well as significant correlations between neighboring CuO2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to [Formula: see text], given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. This is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an "ideal" disorder-free cuprate.

Observation of Orbital Order in the Half-Filled 4f Gd Compound.

Half-filled electron systems, even with the maximized spin angular moment, have been given little attention because of their zero-orbital angular moment according to Hund's rule. Nevertheless, there are several measurements that show evidence of a nonzero orbital moment as well as spin-orbit coupling. Here we report for the first time the orbital order in a half-filled 4f-electron system GdB_{4}, using the resonant soft x-ray scattering at Gd M_{4,5}-edges. Furthermore, we discovered that the development of this orbital order is strongly coupled with the antiferromagnetic spin order. These results clearly demonstrate that even in half-filled electron systems the orbital angular moment can be an important parameter to describe material properties, and may provide significant opportunities for tailoring new correlated electron systems.

The juxtamembrane sequence of the Hepatitis C virus polymerase can affect RNA synthesis and inhibition by allosteric polymerase inhibitors.

The Hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp), nonstructural protein 5B (NS5B), is anchored in the membrane through a C-terminal helix. A sequence of ca. 12 residues that connects the catalytically competent portion of the RdRp and the C-terminal helix, the juxtamembrane sequence (JMS), has a poorly defined role in RdRp function in a large part since it is translated from a cis-acting RNA element (CRE) that is essential for HCV replication. Using a HCV replicon that transposed a second copy of CRE to the 3' UTR of the HCV replicon, we demonstrate that amino acid substitutions in the JMS were detrimental for HCV replicon replication. Substitutions in the JMS also resulted in a defect in de novo-initiated RNAs synthesis in vitro and in a cell-based reporter assay. A nonnucleoside inhibitor of the NS5B that binds to the catalytic pocket was less potent in inhibiting NS5B in the presence of JMS mutations. The JMS mutants exhibit reduced stability in thermodenaturation assays, suggesting that the JMS helps confer a more stable conformation to NS5B that could impact RNA synthesis.

Titanium dxy ferromagnetism at the LaAlO3/SrTiO3 interface.

A number of recent transport and magnetization studies have shown signs of ferromagnetism in the LaAlO3/SrTiO3 heterostructure, an unexpected property with no bulk analogue in the constituent materials. However, no experiment thus far has provided direct information on the host of the magnetism. Here we report spectroscopic investigations of the magnetism using element-specific techniques, including X-ray magnetic circular dichroism and X-ray absorption spectroscopy, along with corresponding model calculations. We find direct evidence for in-plane ferromagnetic order at the interface, with Ti(3+) character in the dxy orbital of the anisotropic t2g band. These findings establish a striking example of emergent phenomena at oxide interfaces.

Enhanced charge density wave with mobile superconducting vortices in La1.885Sr0.115CuO4.

Superconductivity in the cuprates is found to be intertwined with charge and spin density waves. Determining the interactions between the different types of order is crucial for understanding these important materials. Here, we elucidate the role of the charge density wave (CDW) in the prototypical cuprate La1.885Sr0.115CuO4, by studying the effects of large magnetic fields (H) up to 24 Tesla. At low temperatures (T), the observed CDW peaks reveal two distinct regions in the material: a majority phase with short-range CDW coexisting with superconductivity, and a minority phase with longer-range CDW coexisting with static spin density wave (SDW). With increasing magnetic field, the CDW first grows smoothly in a manner similar to the SDW. However, at high fields we discover a sudden increase in the CDW amplitude upon entering the vortex-liquid state. Our results signify strong coupling of the CDW to mobile superconducting vortices and link enhanced CDW amplitude with local superconducting pairing across the H - T phase diagram.

Regulation of de novo-initiated RNA synthesis in hepatitis C virus RNA-dependent RNA polymerase by intermolecular interactions.

The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) has been proposed to change conformations in association with RNA synthesis and to interact with cellular proteins. In vitro, the RdRp can initiate de novo from the ends of single-stranded RNA or extend a primed RNA template. The interactions between the Delta1 loop and thumb domain in NS5B are required for de novo initiation, although it is unclear whether these interactions are within an NS5B monomer or are part of a higher-order NS5B oligomeric complex. This work seeks to address how polymerase conformation and/or oligomerization affects de novo initiation. We have shown that an increasing enzyme concentration increases de novo initiation by the genotype 1b and 2a RdRps while primer extension reactions are not affected or inhibited under similar conditions. Initiation-defective mutants of the HCV polymerase can increase de novo initiation by the wild-type (WT) polymerase. GTP was also found to stimulate de novo initiation. Our results support a model in which the de novo initiation-competent conformation of the RdRp is stimulated by oligomeric contacts between individual subunits. Using electron microscopy and single-molecule reconstruction, we attempted to visualize the low-resolution conformations of a dimer of a de novo initiation-competent HCV RdRp.

Fragile magnetic ground state in half-doped LaSr2Mn2O7.

We investigated the orbital and antiferromagnetic ordering behaviors of the half-doped bilayer manganite La(2-2x)Sr(1+2x)Mn2O7 (x ≃ 0.5) by using Mn L(2,3)-edge resonant soft x-ray scattering. Resonant soft x-ray scattering reveals the CE-type orbital order below T(oo) ≃ 220 K, which shows partial melting behavior below T(m) ≃ 165 K. We also found coexistence CE- and A-type antiferromagnetic orders. Both orders involve the CE-type orbital order with nearly the same orbital character and are coupled with each other. These results manifest that the ground state with the CE-type antiferromagnetic order is easily susceptible to destabilization into the A-type one even with a small fluctuation of the doping level, as suggested by the extremely narrow magnetic phase boundaries at x ≃ 0.5±0.005.