Suppression of lattice doubling in quasi-skutterudite La3Rh4Sn13: a comparison of temperature and hydrostatic pressure routes.

We present structural properties at different temperatures and high-pressure (HP) of La3Rh4Sn13 which is one of the interesting systems in the Remika phase RE3Rh4Sn13 (RE = Sr, Ca, La, Pr, Ce) quasi-skutterudite series using synchrotron diffraction. Data at ambient conditions revealed the presence of several weak reflections, which could be accounted only with a superlattice I* structure (I4132) with lattice parameter a ~19.457 Å. However, above 350 K, a complete suppression of the weak superlattice reflections of the I*  structure is observed. Data at higher temperatures is found to be well described by the I structure (Pm-3n) having half the lattice parameter compared to the I* structure. HP-XRPD at ambient temperature showed that pressures greater than 7.5 GPa result in similar suppression of the weak I* superlattice reflections. Data at higher pressures is found to be well described by the I structure (Pm-3n), similar to the high-temperature phase. HP Raman measurements demonstrated changes that seem to be consistent with a locally more ordered structure as in the case of the I* à I transition. Our findings on La3Rh4Sn13 open up new avenues to study unexplored HP phenomena, especially the superconductivity in these Remika phase quasi-skutterudites.

Insight into intrinsic ferromagnetism in quasi-2D Cr5-yTe8.

Cr5Te8is a half metal with 2D van der Waals ferromagnetic structure and its magnetic properties can be tuned by changing the proportionality of Cr and Te. We report an investigation of magnetization and magnetic anisotropy near the critical transition region of a Cr5-yTe8single crystal with the static and dynamic probes, to unravel the nature of field-dependent spin-spin interactions. The magnetic transition temperatureTCincreasing from 255 K (at near zero-field) to 279 K (at 65 kOe along theab-plane) has been identified. Accordingly, a phase diagram of field versus transition temperature has been established. From the analysis of the field dependence of the critical behavior, we provided evidence that the scenario of 2D Heisenberg-type interactions can be employed to interpret the field-dependent magnetic transitions in Te-rich Cr4.8Te8. The precise picture for the field-reduced spin-spin interaction range has been obtained. The conclusion drawn from the present study demonstrated that Cr4.8Te8is a promising candidate for the spintronic applications with a tunable magnetic transition temperature.

Nodeless superconductivity in the cage-type superconductor Sc5Ru6Sn18 with preserved time-reversal symmetry.

We report the single-crystal synthesis and detailed investigations of the cage-type superconductor Sc5Ru6Sn18, using powder x-ray diffraction (XRD), magnetization, specific-heat and muon-spin relaxation (µSR) measurements. Sc5Ru6Sn18 crystallizes in a tetragonal structure (space group I41/acd) with lattice parameters a = 1.387(3) nm and c = 2.641(5) nm. Both DC and AC magnetization measurements prove the type-II superconductivity in Sc5Ru6Sn18 with T c ≈ 3.5(1) K, a lower critical field [Formula: see text] = 157(9) Oe and an upper critical field, [Formula: see text] = 26(1) kOe. The zero-field electronic specific-heat data are well fitted using a single-gap BCS model, with [Formula: see text] = 0.64(1) meV. The Sommerfeld constant γ varies linearly with the applied magnetic field, indicating s-wave superconductivity in Sc5Ru6Sn18. Specific-heat and transverse-field (TF) µSR measurements reveal that Sc5Ru6Sn18 is a superconductor with strong electron-phonon coupling, with TF-µSR also suggesting a single-gap s-wave character of the superconductivity. Furthermore, zero-field µSR measurements do not detect spontaneous magnetic fields below T c, hence implying that time-reversal symmetry is preserved in Sc5Ru6Sn18.

Magnetic correlations in the intermetallic antiferromagnet Nd3Co4Sn13.

Specific heat, magnetic susceptibility, and neutron scattering have been used to investigate the nature of the spin system in the antiferromagnet Nd3Co4Sn13. At room temperature Nd3Co4Sn13 has a cubic, Pm-3n structure similar to Yb3Rh4Sn13. Antiferromagnetic interactions between, Nd3+ ions dominate the magnetic character of this sample and at 2.4 K the Nd spins enter a long range order state with a magnetic propagation vector q = (0 0 0) with an ordered moment of 1.78(2) µB at 1.5 K. The magnetic Bragg intensity grows very slowly below 1 K, reaching ~2.4 µB at 350 mK. The average magnetic Nd3+ configuration corresponds to the 3D irreducible representation Γ7. This magnetic structure can be viewed as three sublattices of antiferromagnetic spin chains coupled with each other in the 120°-configuration. A well-defined magnetic excitation was measured around the 1 1 1 zone centre and the resulting dispersion curve is appropriate for an antiferromagnet with a gap of 0.20(1) meV.

Electronic and atomic structures of the Sr3Ir4Sn13 single crystal: A possible charge density wave material.

X-ray scattering (XRS), x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopic techniques were used to study the electronic and atomic structures of the high-quality Sr3Ir4Sn13 (SIS) single crystal below and above the transition temperature (T* ≈ 147 K). The evolution of a series of modulated satellite peaks below the transition temperature in the XRS experiment indicated the formation of a possible charge density wave (CDW) in the (110) plane. The EXAFS phase derivative analysis supports the CDW-like formation by revealing different bond distances [Sn1(2)-Sn2] below and above T* in the (110) plane. XANES spectra at the Ir L3-edge and Sn K-edge demonstrated an increase (decrease) in the unoccupied (occupied) density of Ir 5d-derived states and a nearly constant density of Sn 5p-derived states at temperatures T < T* in the (110) plane. These observations clearly suggest that the Ir 5d-derived states are closely related to the anomalous resistivity transition. Accordingly, a close relationship exists between local electronic and atomic structures and the CDW-like phase in the SIS single crystal.

Increased risk of chronic fatigue syndrome following herpes zoster: a population-based study.

Chronic fatigue syndrome (CFS) is a complex disorder accompanied by unexplainable persistent fatigue, in which several etiological factors exist, such as viral infections. Using the National Health Insurance Research Database (NHIRD) of Taiwan, this study evaluated the association between herpes zoster (HZ) infection and the risk of CFS, and examined the possibility of patients developing postviral fatigue effects, including the possibility of developing other unexplainable chronic fatigue conditions. In this prospective cohort study using the NHIRD, we identified 9,205 patients with HZ infection [ICD-9 (International Classification of Disease, Ninth Revision), code 053] and 36,820 patients without HZ infection (non-HZ) from 2005 to 2007, and followed up to the end of 2010. The incidence rate of CFS was higher in the HZ cohort than in the non-HZ cohort (4.56 vs. 3.44 per 1,000 person-years), with an adjusted hazard ratio of 1.29 [95 % confidence interval (CI) = 1.09-1.53]. It was shown that the risk of CFS without comorbidity for each patient increased from 1.25- to 1.36-fold between the CFS and non-CFS cohorts; with long-term follow-up, the HZ cohort showed a significantly higher cumulative incidence rate of developing CFS than the non-HZ patients. We propose that patients with chronic fatigue might exist in a subset of patients that would be associated with HZ infection. The actual mechanism of development of CFS that is attributed to HZ infection remains unclear. The findings of this population cohort study provide pivotal evidence of postviral fatigue among patients with HZ infection.

Chronic fatigue syndrome is associated with the risk of fracture: a nationwide cohort study.

PURPOSE: Chronic fatigue syndrome (CFS) is a complex disorder that is associated with unreasonable persistent fatigue. CFS has also been reported to be a possible risk factor for osteopathy. We propose that CFS might be associated with an increased risk of fracture. METHODS: We used the National Health Insurance Research Database to conduct a prospective cohort study, identifying 3744 patients with a CFS diagnosis (International Classification of Diseases, Ninth Revision, Clinical Modification code 780.71) and 14 976 patients without CFS until 2006, with follow-up observed until the end of 2010. RESULTS: The incidence rate of fracture was higher in the CFS cohort than in the non-CFS cohort (17.44 vs. 14.53 per 1000 person-year, respectively), with an adjusted hazard ratio of 1.14 (95% confidence interval = 1.00-1.30). The risks of fracture between CFS and non-CFS were shown without comorbidity for each would be elevated than with other comorbidities, particularly in osteoporosis. The patients without osteoporosis in the CFS cohort exhibited a 1.16-fold higher risk of fracture than did those in the non-CFS cohort. CONCLUSIONS: We propose that CFS-related fracture might not be associated with osteoporosis. The mechanism for developing CFS-related fracture remains unclear; however, we recommend noticing the prevention of fracture for CFS patients before clarifying the aetiology of CFS-related fracture.

Prevalence and risk factors for age-related macular degeneration in the elderly Chinese population in south-western Taiwan: the Puzih eye study.

AIM: This study aimed to ascertain the prevalence of and the risk factors associated with early and late age-related macular degeneration (AMD) among Chinese individuals aged ≥65 years residing in Puzih, Taiwan. METHODS: This population-based cross-sectional study graded digital colour photographs of the ocular fundus of 673 individuals using the Wisconsin Age-Related Maculopathy Grading System. We compared the characteristics of individuals with early and late AMD using χ(2)-analyses and described risk factors for early and late AMD using odds ratios and 95% confidence intervals. RESULTS: Individuals with late AMD were significantly older and more likely to have hypertension. Further, their sunlight exposure time was longer than that of those with early AMD, only drusen, or no AMD lesions (P<0.01). A history of hyperlipidaemia for >10 years was a significant risk factor for early AMD, while old age, hypertension for >10 years, and exposure to sunlight for >8 h per day were associated with late AMD. CONCLUSIONS: The prevalence rate of early AMD in the present study was 15.0%, which is similar to that reported for Caucasians and Japanese included in the European Eye Study and the Hisayama Study, respectively. The late AMD prevalence rate of 7.3% found among our study participants was comparable to that reported by the Greenland Inuit Eye Study and Reykjavik Study, but considerably lower than that reported for Caucasians, indicating that late AMD might be less prevalent among Asians than Caucasians.

Relationship of diabetic macular oedema with glycosylated haemoglobin.

PURPOSE: To evaluate the correlation between glycosylated haemoglobin (HbA1c) and central foveal thickness as measured by optical coherence tomography (OCT) in patients with diabetes. METHODS: Retrospectively review of medical records of central foveal thickness as measured by OCT and laboratory data of glycosylated haemoglobin. HbA1c was compared with foveal thickness measured by OCT within the preceding 3 months. Clinically significant macular oedema (CSME) was diagnosed if central foveal retinal thickness was greater than 325 mum in OCT. RESULTS: One hundred and two eyes of 102 patients were included in this cross-sectional study. Univariate analysis revealed that the CSME diagnosed by OCT in diabetes was not statistically significant with sex, right or left eye, DM duration over 10 years or not, and AC sugar level (over 140 or not). The HbA1C level (8 or over) and age (50 or less) showed a significant (P=0.005 and 0.006, respectively) and positive association with macular thickness in OCT. A trend towards higher risk was seen for factors of age or=8%. CONCLUSIONS: Patients with HbA1c of 8 or above had an increase in macular thickness in type 2 diabetic eyes and there was a statistical significant correlation between younger age, shorter DM duration and thicker macular thickness. Strict sugar control decreased the risk of diabetic macular retinopathy, and OCT could be an excellent detector of early diabetic macular oedema.