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Supramolecular interactions play an important role in molecular recognition. Cyclodextrins (CDs) are excellent hosts that are frequently utilized in the identification of chemical compounds. Proper modifications to CD can give it the ability to accurately recognize specific molecules. In this research, CD was modified with the allylimidazole moiety to generate a synergistic effect. Remarkably, the newly formed cation probe exhibits selective recognition of 1-adamantanecarboxylic acid from six guest molecules, which cannot be achieved by CD or allylimidazole alone. The recognition is evidenced by the retention of hydrogen-deuterium exchange (HDX) properties in the formed complexes and a change in the chemical shift of protons (H-4, H-5) in the allylimidazol backbone. Wavefunction analysis was employed to demonstrate that the mechanism of molecular recognition is the electrostatic interaction between host and guest molecules as well as the hydrogen bond formed by the guest molecule with the imidazole moiety H-2. This work reports an intramolecular synergistic strategy to specifically identify 1-adamantanecarboxylic acid, which could inspire probe design for various analysts. [ABSTRACT FROM AUTHOR]

The support structure acts as an auxiliary structure for selective laser melting (SLM) part forming. The structural characteristics affect the residual stress distribution of the molded part, necessitating an investigation into its influence on SLM AlSi10Mg alloy. This paper proposes a support structure suitable for processing thin-walled parts based on a combination of numerical simulation and conventional experiments. The experiments are generally consistent with the numerical results, and the study shows that the simulation results can be reliably used to calculate residual stress and strain. The study initiates by comparing the effects of four types of bracing structures on residual stress in various regions of thin-walled parts. A hybrid support structure is obtained by selecting the support structure in different regions. The study thoroughly investigates how the hybrid support structure, with varied support tooth parameters, affects residual stress in different regions of thin-walled parts. Optimal parameters for the hybrid support structure are identified, enhancing its effectiveness in mitigating residual stress. Finally, the milling experiments of the optimal hybrid support structure are carried out, and it is found that the milling force is reduced by about 19% and the flatness is reduced by about 16% compared with other hybrid support structures. [ABSTRACT FROM AUTHOR]

The term "modification" often appears in physics, chemistry, biology, etc., but rarely in structural mechanics, this study proposes the concept of mechanically modified metastructures, which aims to modify conventional mechanical structures so that they can exhibit super-properties never possessed. In this study, we first introduce the coplanarly tension-torsion coupling (TTC) element into ligaments, and then analytically express the effect of the TTC component on the deformation of the general ligamentous model. Then, it is demonstrated that the TTC component can greatly tailor the mechanical properties of the prototypical structure via numerical and experimental results. The positive Poisson's ratio can be transformed into the negative Poisson's ratio by the mechanical modification. Moreover, it is found that the introduced TTC component can assist structures to open new bandgaps, and the location, width, and number of bandgaps can be further tuned by changing the mass and stiffness of the TTC component. This study provides a guideline for altering the mechanical properties of the structures not by changing the main geometric characteristics of the prototypical structure but only by introducing a small structural component. [ABSTRACT FROM AUTHOR]

Indigofera pseudotinctoria Mats is an agronomically and economically important perennial legume shrub with a high forage yield, protein content and strong adaptability, which is subject to natural habitat fragmentation and serious human disturbance. Until now, our knowledge of the genetic relationships and intraspecific genetic diversity for its wild collections is still poor, especially at small spatial scales. Here amplified fragment length polymorphism (AFLP) technology was employed for analysis of genetic diversity, differentiation, and structure of 364 genotypes of I. pseudotinctoria from 15 natural locations in Wushan Montain, a highly structured mountain with typical karst landforms in Southwest China. We also tested whether eco-climate factors has affected genetic structure by correlating genetic diversity with habitat features. A total of 515 distinctly scoreable bands were generated, and 324 of them were polymorphic. The polymorphic information content (PIC) ranged from 0.694 to 0.890 with an average of 0.789 per primer pair. On species level, Nei's gene diversity (Hj), the Bayesian genetic diversity index (HB) and the Shannon information index (I) were 0.2465, 0.2363 and 0.3772, respectively. The high differentiation among all sampling sites was detected (FST = 0.2217, GST = 0.1746, G'ST = 0.2060, өB = 0.1844), and instead, gene flow among accessions (Nm = 1.1819) was restricted. The population genetic structure resolved by the UPGMA tree, principal coordinate analysis, and Bayesian-based cluster analyses irrefutably grouped all accessions into two distinct clusters, i.e., lowland and highland groups. The population genetic structure resolved by the UPGMA tree, principal coordinate analysis, and Bayesian-based cluster analyses irrefutably grouped all accessions into two distinct clusters, i.e., lowland and highland groups. This structure pattern may indicate joint effects by the neutral evolution and natural selection. Restricted Nm was observed across all accessions, and genetic barriers were detected between adjacent accessions due to specifically geographical landform. [ABSTRACT FROM AUTHOR]

Glaciation and mountain orogeny have generated new ecologic opportunities for plants, favoring an increase in the speciation rate. Moreover, they also act as corridors or barriers for plant lineages and populations. High genetic diversity ensures that species are able to survive and adapt. Gene flow is one of the most important determinants of the genetic diversity and structure of out-crossed species, and it is easily affected by biotic and abiotic factors. The aim of this study was to characterize the genetic diversity and structure of an alpine species, Festuca ovina L., in Xinjiang, China. A total of 100 individuals from 10 populations were analyzed using six amplified fragment length polymorphism (AFLP) primer pairs. A total of 583 clear bands were generated, of which 392 were polymorphic; thus, the percentage of polymorphic bands (PPB) was 67.24%. The total and average genetic diversities were 0.2722 and 0.2006 (0.1686-0.2225), respectively. The unweighted group method with arithmetic mean (UPGMA) tree, principal coordinates analysis (PCoA) and Structure analyses revealed that these populations or individuals could be clustered into two groups. The analysis of molecular variance analysis (AMOVA) suggested that most of the genetic variance existed within a population, and the genetic differentiation (Fst) among populations was 20.71%. The Shannon differentiation coefficient (G'st) among populations was 0.2350. Limited gene flow (Nm = 0.9571) was detected across all sampling sites. The Fst and Nm presented at different levels under the genetic barriers due to fragmentation. The population genetic diversity was significant relative to environmental factors such as temperature, altitude and precipitation. [ABSTRACT FROM AUTHOR]

Purpose: Several publications have investigated the association between the Cyclin D1 G to A substitution at nucleotide 870 (CCND1 G870A) polymorphism and squamous cell carcinoma (SCC) of the upper aerodigestive tract (UADT), but their conclusions still remain controversial. We conducted a meta-analysis to precisely evaluate this association. Patients and methods: We electronically searched the Chinese National Knowledge Infrastructure, PubMed, and Embase (up to January 2015) databases for case-control studies on the association between the CCND1 G870A polymorphism and SCC of the UADT, and 23 studies were included in total. Results: The meta-analysis results showed that there was a significant association between the CCND1 G870A polymorphism and the risk of SCC of the UADT (AA vs GG: odds ratio [OR] =1.33, 95% confidence interval [CI] =1.01-1.74, P,0.001 for heterogeneity; GA/AA vs GG: OR =1.24, 95% CI =1.01-1.51, P,0.001 for heterogeneity; AA vs GA/GG: OR =1.16, 95% CI =0.97-1.39, P,0.001 for heterogeneity; allele A vs allele G: OR =1.14, 95% CI =1.00-1.30, P,0.001 for heterogeneity; GA vs GG: OR =1.18, 95% CI =0.98-1.42, P,0.001 for heterogeneity). However, when analyzing prognosis, allele G was a potential risk factor for poor tumor differentiation (AA vs GA/GG: OR =2.60, 95% CI =1.15-5.86, P=0.836 for heterogeneity) and reduced disease-free intervals (OR =2.08, 95% CI =1.17-3.69, P=0.134 for heterogeneity). In the subgroup analysis, the cancer susceptibility of Asian groups, populationbased control groups, nasopharyngeal cancer groups, and esophageal SCC groups were more likely to be affected by the CCND1 G870A polymorphism. No significant publication bias was found in our analysis (P=0.961 for Egger's test and P=0.245 for Begg's test). Conclusion: The results of the present meta-analysis suggest that the variant CCND1 870A allele might confer an elevated risk of SCC of the UADT, particularly among Asians and individuals who have esophageal or nasopharyngeal cancers. Moreover, the CCND1 870A allele might also confer better tumor differentiation grades and longer disease-free intervals. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering (INS) to study the spin excitations in partially detwinned NaFe0.985Co0.015As which has coexisting static antiferromagnetic (AF) order and superconductivity (Tc=15 K, TN=30 K). In previous INS work on a twinned sample, spin excitations formed a dispersive sharp resonance near Er1=3.25 meV and a broad dispersionless mode at Er1=6 meV at the AF ordering wave vector QAF=Q1=(1,0) and its twinned domain Q2=(0,1). For partially detwinned NaFe0.985Co0.015As with the static AF order mostly occurring at QAF=(1,0), we still find a double resonance at both wave vectors with similar intensity. Since Q1=(1,0) characterizes the explicit breaking of the spin rotational symmetry associated with the AF order, these results indicate that the double resonance cannot be due to the static and fluctuating AF orders but originate from the superconducting gap anisotropy. [ABSTRACT FROM AUTHOR]

We use polarized inelastic neutron scattering (INS) to study spin excitations in superconducting NaFe0.985Co0.015As (C15) with static antiferromagnetic (AF) order along the a axis of the orthorhombic structure and NaFe0.935Co0.045As (C45) without AF order. In previous unpolarized INS work, spin excitations in C15 were found to have a dispersive sharp resonance near Er1 = 3 .2 5 meV and a broad dispersionless mode at Er2 = 6 meV. Our neutron polarization analysis reveals that the dispersive resonance in C 15 is highly anisotropic and polarized along the a and c axes, while the dispersionless mode is isotropic similar to that of C45. Since the n-axis polarized spin excitations of the anisotropic resonance appear below Tc, our data suggests that the itinerant electrons contributing to the magnetism are also coupled to the superconductivity. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering to study spin waves in the antiferromagnetic ordered phase of iron pnictide NaFeAs throughout the Brillouin zone. Comparing with the well-studied AFe2As2 (A = Ca, Sr, Ba) family, spin waves in NaFeAs have considerably lower zone boundary energies and more isotropic effective in-plane magnetic exchange couplings. These results are consistent with calculations from a combined density functional theory and dynamical mean field theory and provide strong evidence that pnictogen height controls the strength of electron-electron correlations and consequently the effective bandwidth of magnetic excitations. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering to show that superconductivity in electron-underdoped NaFe0.985Co0.015As induces a dispersive sharp resonance near Er1=3.25 meV and a broad dispersionless mode at Er2=6 meV. However, similar measurements on overdoped superconducting NaFe0.935Co0.045As find only a single sharp resonance at Er=7 meV. We connect these results with the observations of angle-resolved photoemission spectroscopy that the superconducting gaps in the electron Fermi pockets are anisotropic in the underdoped material but become isotropic in the overdoped case. Our analysis indicates that both the double neutron spin resonances and gap anisotropy originate from the orbital dependence of the superconducting pairing in the iron pnictides. Our discovery also shows the importance of the inelastic neutron scattering in detecting the multiorbital superconducting gap structures of iron pnictides. [ABSTRACT FROM AUTHOR]

A determination of the superconducting (SC) electron pairing symmetry forms the basis for establishing a microscopic mechanism for superconductivity. For iron pnictide superconductors, the s±-pairing symmetry theory predicts the presence of a sharp neutron spin resonance at an energy below the sum of hole and electron SC gap energies (E ⩽ 2Δ) below Tc. On the other hand, the s++-pairing symmetry expects a broad spin excitation enhancement at an energy above 2Δ below Tc. Although the resonance has been observed in iron pnictide superconductors at an energy below 2Δ consistent with the s±-pairing symmetry, the mode has also been interpreted as arising from the s++-pairing symmetry with E ≳ 2Δ due to its broad energy width and the large uncertainty in determining the SC gaps. Here we use inelastic neutron scattering to reveal a sharp resonance at E = 7 meV in SC NaFe0.935Co0.045As (Tc = 18 K). On warming towards Tc, the mode energy hardly softens while its energy width increases rapidly. By comparing with calculated spin-excitation spectra within the s± and s++-pairing symmetries, we conclude that the ground-state resonance in NaFe0.935Co0.045As is only consistent with the s± pairing, and is inconsistent with the s++-pairing symmetry. [ABSTRACT FROM AUTHOR]

We use polarized inelastic neutron scattering (INS) to study spin excitations of optimally hole-doped superconductor Ba 0.67K0.33Fe2As2 (Tc = 38 K). In the normal state, the imaginary part of the dynamic susceptibility, χ"(Q, w), shows magnetic anisotropy for energies below ~7 meV with c-axis polarized spin excitations larger than that of the in-plane component. Upon entering into the superconducting state, previous unpolarized INS experiments have shown that spin gaps at ~5 and 0.75 meV open at wave vectors Q = (0.5, 0.5,0) and (0.5, 0.5,1), respectively, with a broad neutron spin resonance at Er = 15 meV. Our neutron polarization analysis reveals that the large difference in spin gaps is purely due to different spin gaps in the c axis and in-plane polarized spin excitations, resulting in a resonance with different energy widths for the c-axis and in-plane spin excitations. The observation of spin anisotropy in both optimally electron- and hole-doped BaFe2As2 is due to their proximity to the AF ordered BaFe2As2 where spin anisotropy exists below TN. [ABSTRACT FROM AUTHOR]

We use time-of-flight (TOF) inelastic-neutron-scattering (INS) spectroscopy to investigate the doping dependence of magnetic excitations across the phase diagram of NaFe1-xCoxAs with x=0, 0.0175, 0.0215, 0.05, and 0.11. The effect of electron doping by partially substituting Fe by Co is to form resonances that couple with superconductivity, broaden, and suppress low-energy (E=80 meV) spin excitations compared with spin waves in undoped NaFeAs. However, high-energy (E>80 meV) spin excitations are weakly Co-doping-dependent. Integration of the local spin dynamic susceptibility χ″(ω) of NaFe1-xCoxAs reveals a total fluctuating moment of 3.6 µ2B/Fe and a small but systematic reduction with electron doping. The presence of a large spin gap in Co-overdoped nonsuperconducting NaFe0.89Co0.11As suggests that Fermi surface nesting is responsible for low-energy spin excitations. These results parallel the Ni-doping evolution of spin excitations in BaFe2-xNixAs2 in spite of the differences in crystal structures and Fermi surface evolution in these two families of iron pnictides, thus confirming the notion that low-energy spin excitations coupling with itinerant electrons are important for superconductivity, while weakly doping-dependent high-energy spin excitations result from localized moments. [ABSTRACT FROM AUTHOR]

Neutron spin resonance, a collective magnetic excitation coupled to superconductivity, is one of the most prominent features shared by a broad family of unconventional superconductors including copper oxides, iron pnictides, and heavy fermions. In this paper, we study the doping evolution of the resonances in NaFe1-xCoxAs covering the entire superconducting dome. For the underdoped compositions, two resonance modes coexist. As doping increases, the low-energy resonance gradually loses its spectral weight to the high-energy one but remains at the same energy. By contrast, in the overdoped regime we only find one single resonance, which acquires a broader width in both energy and momentum but retains approximately the same peak position even when Tc drops by nearly a half compared to optimal doping. These results suggest that the energy of the resonance in electron overdoped NaFe1-xCoxAs is neither simply proportional to Tc nor the superconducting gap but is controlled by the multiorbital character of the system and doped impurity scattering effect. [ABSTRACT FROM AUTHOR]

High-temperature superconductivity in iron pnictides occurs when electrons are doped into their antiferromagnetic (AF) parent compounds. In addition to inducing superconductivity, electron doping also changes the static commensurate AF order in the undoped parent compounds into short-range incommensurate AF order near optimal superconductivity. Here we use neutron scattering to demonstrate that the incommensurate AF order in BaFe2-x Nix As2 is not a spin-density wave arising from the itinerant electrons in nested Fermi surfaces, but is consistent with a cluster spin glass in the matrix of the superconducting phase. Therefore, optimal superconductivity in iron pnictides coexists and competes with a mesoscopically separated cluster spin glass phase, much different from the homogeneous coexisting AF and superconducting phases in the underdoped regime. [ABSTRACT FROM AUTHOR]

We use unpolarized and polarized inelastic neutron scattering to study low-energy spin excitations in NaFeAs, which exhibits a tetragonal-to-orthorhombic lattice distortion at Ts≈58 K followed by a collinear antiferromagnetic (AF) order below TN≈45 K. In the AF ordered state (TTs), spin excitations become more isotropic. Since similar magnetic anisotropy is also observed in the paramagnetic tetragonal phase of superconducting BaFe1.904Ni0.096As2, our results suggest that the spin excitation anisotropy in superconducting iron pnictides originates from similar anisotropy already present in their parent compounds. [ABSTRACT FROM AUTHOR]

We use polarized neutron scattering to demonstrate that in-plane spin excitations in electron doped superconducting BaFe1.904Ni0.096As2 (Tc=19.8 K) change from isotropic to anisotropic in the tetragonal phase well above the antiferromagnetic (AFM) ordering and tetragonal-to-orthorhombic lattice distortion temperatures (TN≈Ts=33±2 K) without an uniaxial pressure. While the anisotropic spin excitations are not sensitive to the AFM order and tetragonal-to-orthorhombic lattice distortion, superconductivity induces further anisotropy for spin excitations along the [110] and [1̅10] directions. These results indicate that the spin excitation anisotropy is a probe of the electronic anisotropy or orbital ordering in the tetragonal phase of iron pnictides. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering to study the temperature dependence of the low-energy spin excitations in single crystals of superconducting FeTe0.6Se0.4 (Tc = 14 K). In the low-temperature superconducting state, the imaginary part of the dynamic susceptibility at the electron and hole Fermi-surfaces nesting wave vector Q = (0.5,0.5), x "(Q,o), has a small spin gap, a two-dimensional neutron spin resonance above the spin gap, and increases linearly with increasing ha> for energies above the resonance. While the intensity of the resonance decreases like an order parameter with increasing temperature and disappears at temperature slightly above Tc, the energy of the mode is weakly temperature dependent and vanishes concurrently above Tc. This suggests that in spite of its similarities with the resonance in electron-doped superconducting BaFe2-x(Co,Ni)xAs2, the mode in FeTe0.6Se0.4 is not directly associated with the superconducting electronic gap. [ABSTRACT FROM AUTHOR]

The immunosuppressive and hypoxic tumor microenvironment (TME) remains a major obstacle to impede cancer immunotherapy. Here, we showed that elevated levels of Delta-like 1 (DLL1) in the breast and lung TME induced long-term tumor vascular normalization to alleviate tumor hypoxia and promoted the accumulation of interferon? (IFN-γ)-expressing CD8+ T cells and the polarization of M1-like macrophages. Moreover, increased DLL1 levels in the TME sensitized anti-cytotoxic T lymphocyte-associated protein 4 (anti-CTLA4) treatment in its resistant tumors, resulting in tumor regression and prolonged survival. Mechanically, in vivo depletion of CD8+ T cells or host IFN-γ deficiency reversed tumor growth inhibition and abrogated DLL1-induced tumor vascular normalization without affecting DLL1-mediated macrophage polarization. Together, these results demonstrate that elevated DLL1 levels in the TME promote durable tumor vascular normalization in a CD8+ T cell- and IFN-γ-dependent manner and potentiate anti-CTLA4 therapy. Our findings unveil DLL1 as a potential target to persistently normalize the TME to facilitate cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Immune checkpoint blockade (ICB) has demonstrated curative potential in several types of cancer, but only for a small number of patients. Thus, the identification of reliable and noninvasive biomarkers for predicting ICB responsiveness is an urgent unmet need. Here, we show that ICB increased tumor vessel perfusion in treatment-sensitive EO771 and MMTV-PyVT breast tumor as well as CT26 and MCA38 colon tumor models, but not in treatment-resistant MCaP0008 and 4T1 breast tumor models. In the sensitive tumor models, the ability of anti-cytotoxic T lymphocyte-associated protein 4 or anti-programmed cell death 1 therapy to increase vessel perfusion strongly correlated with its antitumor efficacy. Moreover, globally enhanced tumor vessel perfusion could be detected by Doppler ultrasonography before changes in tumor size, which predicted final therapeutic efficacy with more than 90% sensitivity and specificity. Mechanistically, CD8+ T cell depletion, IFN-γ neutralization, or implantation of tumors in IFN-γ receptor knockout mice abrogated the vessel perfusion enhancement and antitumor effects of ICB. These results demonstrated that ICB increased vessel perfusion by promoting CD8+ T cell accumulation and IFN-γ production, indicating that increased vessel perfusion reflects the successful activation of antitumor T cell immunity by ICB. Our findings suggest that vessel perfusion can be used as a novel noninvasive indicator for predicting ICB responsiveness. [ABSTRACT FROM AUTHOR]

We use unpolarized and polarized neutron scattering to study the temperature and polarization dependence of low-energy magnetic fluctuations in nearly optimally doped NaFe0.9785 Co0.0215 As, with coexisting superconductivity (Tc ≈ 19 K) and weak antiferromagnetic order (TN ≈ 30 K, ordered moment ≈ 0.02 µB/Fe). A single spin resonance mode with intensity tracking the superconducting order parameter is observed, although energy of the mode only softens slightly upon approaching Tc. Polarized neutron scattering reveals that the single resonance is mostly isotropic in spin space, similar to overdoped NaFe0.935 Co0.045 As but different from optimal electron-, hole-, and isovalently doped BaFe2 As2 compounds, all featuring an additional prominent anisotropic component. Spin anisotropy in NaFe0.9785 Co0.0215 As is instead present at energies below the resonance, which becomes partially gapped below Tc, similar to the situation in optimally doped YBa2 Cu3 O6.9. Our results indicate that anisotropic spin fluctuations in NaFe1-x Cox As appear in the form of a resonance in the underdoped regime, become partially gapped below Tc near optimal doping, and disappear in overdoped compounds. [ABSTRACT FROM AUTHOR]

Both extrinsic and intrinsic tissues contribute to tendon repair, but the origin and molecular functions of extrinsic tissues in tendon repair are not fully understood. Here we show that tendon sheath cells harbor stem/progenitor cell properties and contribute to tendon repair by activating Hedgehog signaling. We found that Osteocalcin (Bglap) can be used as an adult tendon- sheath-specific marker in mice. Lineage tracing experiments show that Bglap-expressing cells in adult sheath tissues possess clonogenic and multipotent properties comparable to those of stem/progenitor cells isolated from tendon fibers. Transplantation of sheath tissues improves tendon repair. Mechanistically, Hh signaling in sheath tissues is necessary and sufficient to promote the proliferation of Mkx-expressing cells in sheath tissues, and its action is mediated through TGFβ/Smad3 signaling. Furthermore, co-localization of GLI1+ and MKX+ cells is also found in human tendinopathy specimens. Our work reveals the molecular function of Hh signaling in extrinsic sheath tissues for tendon repair. [ABSTRACT FROM AUTHOR]

RATIONALE: The snub-nosed monkey genus Rhinopithecus comprises five allopatric and morphologically differentiated species, the black-white snub-nosed monkey Rhinopithecus bieti, the black snub-nosed monkey Rhino-pithecus strykeri, the golden snub-nosed monkey Rhinopithecus roxellana, the gray snub-nosed monkey Rhinopithecus brelichi, and the Tonkin snub-nosed monkey Rhinopithecus avunculus. Alleles of these genes were alternately inherited from each parent, likely producing the mosaic coat coloration of the hybrid monkey and promoting premating reproductive isolation of the hybrid species from both parents. To examine the speciation histories of these species, we generated a chromosome-level high-quality reference genome assembly for the black-white snub-nosed monkey and analyzed 106 resequenced genomes of individuals from all five species. [Extracted from the article]

We use transport and neutron diffraction to study the electronic phase diagram of NaFe1-xCoxAs. In the undoped state, NaFeAs exhibits a tetragonal-to-orthorhombic structural transition below Ts followed by a collinear antiferromagnetic (AF) order below TN. Upon codoping to form NaFe1-xCoxAs,Ts and TN are gradually suppressed, leading to optimal superconductivity near Co-doping x=0.025. While transport experiments on these materials reveal an anomalous behavior suggesting the presence of a quantum critical point (QCP) near optimal superconductivity, our neutron diffraction results indicate that commensurate AF order becomes transversely incommensurate with TN>Tc before vanishing abruptly at optimal superconductivity. These results are remarkably similar to electron-doping and isovalent-doping evolution of the AF order in BaFe2-xNixAs2 and BaFe2(As1-xPx)2, thus suggesting a universal behavior in the suppression of the magnetic order in iron pnictides as superconductivity is induced. [ABSTRACT FROM AUTHOR]

The carnivoran giant panda has a specialized bamboo diet, to which its alimentary tract is poorly adapted. Measurements of daily energy expenditure across five captive and three wild pandas averaged 5.2 megajoules (MJ)/day, only 37.7% of the predicted value (13.8 MJ/day). For the wild pandas, the mean was 6.2 MJ/day, or 45% of the mammalian expectation. Pandas achieve this exceptionally low expenditure in part by reduced sizes of several vital organs and low physical activity. In addition, circulating levels of thyroid hormones thyroxine (T4) and triiodothyronine (T3) averaged 46.9 and 64%, respectively, of the levels expected for a eutherian mammal of comparable size. A giant panda-unique mutation in the DUOX2 gene, critical for thyroid hormone synthesis, might explain these low thyroid hormone levels. A combination of morphological, behavioral, physiological, and genetic adaptations, leading to low energy expenditure, likely enables giant pandas to survive on a bamboo diet. [ABSTRACT FROM AUTHOR]

We report a detailed nuclear magnetic resonance (NMR) study by combined 23Na and 75 As measurements over abroad range of doping to map the phase diagram of NaFe1-xCoxAs. In the underdoped regime (x ≤ 0.017), we find a magnetic phase with robust antiferromagnetic (AFM) order, which we denote the s-AFM phase, cohabiting with a phase of weak and possibly proximity-induced AFM order (ω-AFM) whose volume fraction V ≃ 8% is approximately constant. Near optimal doping, at x = 0.0175, we observe a phase separation between static antiferromagnetism related to the s-AFM phase and a paramagnetic (PM) phase related to w-AFM. The volume fraction of AFM phase increases upon cooling, but both the Neel temperature and the volume fraction can be suppressed systematically by applying a c-axis magnetic field. On cooling below Tcs superconductivity occupies the PM region and its volume fraction grows at the expense of the AFM phase, demonstrating a phase separation of the two types of order based on volume exclusion. At higher dopings, static antiferromagnetism and even critical AFM fluctuations are completely suppressed by superconductivity. Thus the phase diagram we establish contains two distinct types of phase separation and reflects a strong competition between AFM and superconducting phases both in real space and in momentum space. We suggest that both this strict mutual exclusion and the robustness of superconductivity against magnetism are consequences of the extreme two-dimensionality of NaFeAs. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering and dielectric constant measurements to study the doping influence on the spin dynamics and magnetoelectric (ME) effect in hexagonal Y0.7Lu0.3MnO3. In undoped YMn03 and LuMn03, the Mn trimerization distortion has been suggested to play a key role in determining the magnetic structure and the magnetoelectric effect. In Y0.7Lu0.3MnO3, at the antiferromagnetic zone center, we observed a much smaller Δw ∞ 0.52 meV gap (which is ∼2.5 meV for both YMn03 and LuMn03) that coincides with a weaker in-plane dielectric anomaly at TN; both can be attributed to a weaker Mn trimerization distortion in Y0.7Lu0.3MnO3 compared to YMn03 and LuMn03. The results provide strong evidence that the magnitude of ME coupling is linked to the strength of the trimerization distortion, suggesting the Mn trimerization is responsible for the ME effect in Y1-yLuyMnO3. [ABSTRACT FROM AUTHOR]

We have performed detailed 57Fe Mössbauer spectroscopy measurements on Ba0.75K0.25Fe2As2 single-crystal mosaics showing antiferromagnetic ordering below TN = 95 K with superconductivity below TC around 30 K. Analysis of the Mössbauer spectra shows a decrease in the magnetic hyperfine field but no change in the magnetic volume fraction below TC. This indicates coexistence of magnetism and superconductivity in these compounds. [ABSTRACT FROM AUTHOR]

We use neutron scattering to study the effect of uniaxial pressure on the tetragonal-to-orthorhombic structural (Ts) and paramagnetic-to-antiferromagnetic (TN) phase transitions in NaFeAs and compare the outcome with similar measurements on as-grown and annealed BaFe2As2. In previous work on as-grown BaFe2As2, uniaxial pressure necessary to detwin the sample was found to induce a significant increase in zero pressure TN and Ts. However, we find that similar uniaxial pressure used to detwin NaFeAs and annealed BaFe2As2 has a very small effect on their TN and Ts. Since transport measurements on these samples still reveal resistivity anisotropy above TN and Ts, we conclude diat such anisotropy can not be due to uniaxial strain-induced TN and Ts shifts, but must arise from intrinsic electronic anisotropy in these materials. [ABSTRACT FROM AUTHOR]

We study the normal-state and superconducting properties of the NaFe1-xCoxAs system by specific heat measurements. Both the normal-state Sommerfeld coefficient and superconducting condensation energy are strongly suppressed in the underdoped and heavily overdoped samples. The low-temperature electronic specific heat can be well fitted by either a one-gap or a two-gap BCS-type function for all the superconducting samples. The ratio γNTc2/Hc2(0) can nicely associate the neutron spin resonance as the bosons in the standard Eliashberg model. However, the value of ΔC/TcγN near optimal doping is larger than the maximum value the model can obtain. Our results suggest that the high-Tc superconductivity in the Fe-based superconductors may be understood within the framework of boson-exchange mechanism but significant modification may be needed to account for the finite-temperature properties. [ABSTRACT FROM AUTHOR]

Background: Infection with pathogenic Leptospira species causes serious systemic inflammation in patients. Although a few leptospiral proinflammatory molecules have been identified, Leptospira likely encodes other unidentified strong inflammation stimulators. The pathogenic L. interrogans genome encodes numerous putative hemolysin genes. Since hemolysins from other bacteria can cause inflammatory reactions, we hypothesized that leptospiral hemolysins may function as proinflammatory stimulators that contribute to the strong inflammation associated with Leptospira infection. Methodology/Principal Findings: We first used cytokine protein microarrays for systematic analysis of serum cytokine profiles in leptospirosis patients and leptospire-infected mice. We found that IL-1β, IL-6 and TNF-α were the main proinflammatory cytokines in the sera of both the patients and the mice. We then analyzed eight putative hemolysins in L. interrogans strain Lai. The results showed that five of them, Sph1, Sph2, Sph3, HlpA and TlyA were secreted and had hemolytic activity. More importantly, these five hemolysins induced the strong production of IL-1β, IL-6 and TNF-α in human and mouse macrophages (although a bit lower in the latter). Furthermore, blockade of TLR2 or TLR4 with either antibodies or inhibitors of the NF-κB or JNK signaling pathways significantly reduced the production of hemolysin-induced IL-1β, IL-6 and TNF-α. Macrophages isolated from TLR2-, TLR4-or double TLR2-and 4- deficient mice also confirmed that the leptospiral hemolysins that induce proinflammatory cytokines are both TLR2-and TLR4-dependent. Conclusions/Significance: Our findings demonstrate that L. interrogans secretes many hemolysins that function as powerful inducers of proinflammatory cytokines through both TLR2-and TLR4-dependent JNK and NF-κB pathways. [ABSTRACT FROM AUTHOR]

Iron-arsenide superconductor Na1-&dgrFeAs is highly reactive with the environment. Due to the high mobility of Na ions, this reaction affects the entire bulk of the crystals and leads to an effective stoichiometry change. Here we use this effect to study the doping evolution of normal and superconducting properties of the same single crystals. Controlled reaction with air increases the superconducting transition temperature Tc, from the initial value of 12 to 27 K. as probed by transport and magnetic measurements. Similar effects are observed in samples reacted with Apiezon N grease, which slows down the reaction rate and results in more homogeneous samples. In both cues, the temperature-dependent resistivity &rgr;a(T) shows a dramatic change with exposure time. In freshly prepared samples, &rgr;a(T) reveals clear features at the tetragonal-to-orthorhombic (Ts ≈ 60 K) and antiferromagnetic (Tm = 45 K) transitions and superconductivity with onset Tc,ons = 16 K and offset Tc,off = 12 K. The exposed samples show T-linear variation of &rgr;a(T) above Tc,ons = 30 K (Tc,off = 26 K), suggesting bulk character of the observed doping evolution and implying the existence of a quantum critical point at the optimal doping. The resistivity for different doping levels is affected below ∼200 K suggesting the existence of a characteristic energy scale that terminates the T-linear regime, which could be identified with a pseudogap. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering to study the low-energy spin excitations in moderately doped nonsuperconducting Fe1.01Te0.72Se0.28. The spin excitations in this system contain components near (0.5,0,0) and (0.5,0.5,0) in a-b plane reciprocal lattice units using tetragonal unit cell notation (α = b = 3.772 Å and c = 6.061 Å At low energies the scattering is centered around (0.5,0,0). With increasing energy, the spectral weight of low-energy spin excitations centered around (0.5,0,0) abruptly shifts around 3 meV to the incommensurate spin excitations centered around (0.5,0.5,0). However both types of spin fluctuations exhibit the identical temperature dependence. These results indicate that the (0.5,0,0)-type spin excitations and the incommensurate excitations around the (0.5,0.5,0) position have a common origin and both must be taken into account to understand the nature of magnetism and superconducting pairing in the iron chalcogenides. [ABSTRACT FROM AUTHOR]

We use inelastic neutron scattering to study the effect of an in-plane magnetic field on the magnetic resonance in optimally doped superconductors FeSe0.4Te0.6 (Tc=14 K) and BaFe1.9Ni0.1As2 (Tc=20 K). While the magnetic field up to 14.5 T does not change the energy of the resonance, it partially suppresses Tc and the corresponding superconductivity-induced intensity gain of the mode. However, we find no direct evidence for the field-induced spin-1 Zeeman splitting of the resonance. Therefore it is still unclear if the resonance is the long-sought singlet-triplet excitation directly coupled to the superconducting electron Cooper pairs. [ABSTRACT FROM AUTHOR]

We report infrared studies of AFe2As2 (A=Ba, Sr), two representative parent compounds of iron-arsenide superconductors, at magnetic fields (B) up to 17.5 T. Optical transitions between Landau levels (LLs) were observed in the antiferromagnetic states of these two parent compounds. Our observation of a √B dependence of the LL transition energies, the zero-energy intercepts at B=0 T under the linear extrapolations of the transition energies and the energy ratio (~2.4) between the observed LL transitions, combined with the linear band dispersions in two-dimensional (2D) momentum space obtained by theoretical calculations, demonstrates the existence of massless Dirac fermions in the antiferromagnet BAFe2As2. More importantly, the observed dominance of the zeroth-LL-related absorption features and the calculated bands with extremely weak dispersions along the momentum direction kz indicate that massless Dirac fermions in BAFe2As2 are 2D. Furthermore, we find that the total substitution of the barium atoms in BAFe2As2 by strontium atoms not only maintains 2D massless Dirac fermions in this system, but also enhances their Fermi velocity, which supports that the Dirac points in iron-arsenide parent compounds are topologically protected. [ABSTRACT FROM AUTHOR]

Using polarization-resolved electronic Raman scattering we study underdoped, optimally doped, and overdoped Ba1-xKxFe2As2 samples in the normal and superconducting states. We show that low-energy nematic fluctuations are universal for all studied doping ranges. In the superconducting state, we observe two distinct superconducting pair-breaking peaks corresponding to one large and one small superconducting gap. In addition, we detect a collective mode below the superconducting transition in the B2g channel and determine the evolution of its binding energy with doping. Possible scenarios are proposed to explain the origin of the in-gap collective mode. In the superconducting state of the underdoped regime, we detect a reentrance transition below which the spectral background changes and the collective mode vanishes. [ABSTRACT FROM AUTHOR]

We use polarized inelastic neutron scattering to study the temperature and energy dependence of spin space anisotropies in the optimally-hole-doped iron pnictide Ba0.67K0.33Fe2As2 (Tc = 38 K). In the superconducting state, while the high-energy part of the magnetic spectrum is nearly isotropic, the low-energy part displays a pronounced anisotropy, manifested by a c-axis polarized resonance. We also observe that the spin anisotropy in superconducting Ba0.67K0.33Fe2As2 extends to higher energies compared with electron-doped BaFe2-xTMxAs2 (TM = Co, Ni) and isovalent-doped BaFe2As1.4P0.6, suggesting a connection between Tc and the energy scale of the spin anisotropy. In the normal state, the low-energy spin anisotropy for hole- and electron-doped iron pnictides near optimal superconductivity onset at temperatures similar to the temperatures at which the elastoresistance deviates from Curie-Weiss behavior, pointing to a possible connection between the two phenomena. Our results highlight the relevance of the spin-orbit coupling to the superconductivity of the iron pnictides. [ABSTRACT FROM AUTHOR]

We use neutron scattering to study spin excitations in single crystals of LiFe0.88Co0.12As, which is located near the boundary of the superconducting phase of LiFe1-xCoxAs and exhibits non-Fermi-liquid behavior indicative of a quantum critical point. By comparing spin excitations of LiFe0.88Co0.12As with a combined density functional theory and dynamical mean field theory calculation, we conclude that wave-vector correlated low energy spin excitations are mostly from the dxy orbitals, while high-energy spin excitations arise from the dyz and dxz orbitals. Unlike most iron pnictides, the strong orbital selective spin excitations in the LiFeAs family cannot be described by an anisotropic Heisenberg Hamiltonian. While the evolution of low-energy spin excitations of LiFe1-xCoxAs is consistent with the electron-hole Fermi surface nesting conditions for the dxy orbital, the reduced superconductivity in LiFe0.88Co0.12As suggests that Fermi surface nesting conditions for the dyz and dxz orbitals are also important for superconductivity in iron pnictides. [ABSTRACT FROM AUTHOR]

The multiband nature of iron pnictides gives rise to a rich temperature-doping phase diagram of competing orders and a plethora of collective phenomena. At low dopings, the tetragonal-to-orthorhombic structural transition is closely followed by a spin-density-wave transition both being in close proximity to the superconducting phase. A key question is the nature of high-Tc superconductivity and its relation to orbital ordering and magnetism. Here we study the NaFe1−xCoxAs superconductor using polarization-resolved Raman spectroscopy. The Raman susceptibility displays critical enhancement of nonsymmetric charge fluctuations across the entire phase diagram, which are precursors to a d-wave Pomeranchuk instability at temperature θ(x). The charge fluctuations are interpreted in terms of quadrupole interorbital excitations in which the electron and hole Fermi surfaces breathe in-phase. Below Tc, the critical fluctuations acquire coherence and undergo a metamorphosis into a coherent in-gap mode of extraordinary strength. [ABSTRACT FROM AUTHOR]