Nuclear Magnetic Resonance in Solid Hydrogen with Various Ortho Concentrations

Nuclear magnetic resonance in solid hydrogen with various ortho concentrations was studied at low temperatures down to 1.17°K. The results on normal hydrogen were in agreement with those of Reif and Purcell. The width of the center peak at 4.2°K was 5.4 gauss in normal hydrogen and decreased with falling ortho concentration. In crystals with the concentration higher than 63 per cent, two side peaks with the separation of 39.5 gauss appeared at temperatures characteristic of the concentration. The center peak in low concentration hydrogen showed a fine structure at low temperatures. The theoretical considerations of Reif and Purcell concerning the state of solid hydrogen were examined and extended to interpret the results. Their assumption of asymmetric crystalline potential which lifts the rotational degeneracy of the ortho molecule was capable of explaining most of the experimental results in ortho-para mixures. The appearance of side peaks was attributed to the onset of cooperative ordering of the axes of rotation of the ortho molecules. The fine structure in low concentration hydrogen was considered to be due to the different local surroundings of the ortho molecules. The well-known specific heat anomaly and the ortho-para conversion in the solid were discussed on the same basis. The magnetic resonance absorption in solid deuterium was also studied in connection with the present problem

11^{11}B NMR study of pure and lightly carbon doped MgB2_2 superconductors

We report a $^{11}$B NMR line shape and spin-lattice relaxation rate ($1/(T_1T)$) study of pure and lightly carbon doped MgB$_{2-x}$C$_{x}$ for $x=0$, 0.02, and 0.04, in the vortex state and in magnetic field of 23.5 kOe. We show that while pure MgB$_2$ exhibits the magnetic field distribution from superposition of the normal and the Abrikosov state, slight replacement of boron with carbon unveils the magnetic field distribution of the pure Abrikosov state. This indicates a considerable increase of $H_{c2}^c$ with carbon doping with respect to pure MgB$_2$. The spin-lattice relaxation rate $1/(T_1T)$ demonstrates clearly the presence of a coherence peak right below $T_c$ in pure MgB$_2$, followed by a typical BCS decrease on cooling. However, at temperatures lower than $\approx 10$K strong deviation from the BCS behavior is observed, probably from residual contribution of the vortex dynamics. In the carbon doped systems both the coherence peak and the BCS temperature dependence of $1/(T_1T)$ weaken, an effect attributed to the gradual shrinking of the $\sigma$ hole cylinders of the Fermi surface with electron doping.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

Granulomatosis with Polyangiitis Presenting as a Choroidal Tumor

Granulomatosis with polyangiitis (GPA) sometimes involves the eye orbit; however, choroidal involvements in GPA had been rarely reported. We report a rare case presenting with a choroidal mass in an 83-year-old Japanese woman who presented with left eye pain. Diagnostic biopsy revealed necrotizing vasculitis with infiltrates of inflammatory cells. Diagnosis was localized granulomatosis with polyangiitis. Combined treatments with corticosteroid plus azathioprine resolved the choroidal mass region. Although treatment with corticosteroid and immunosuppressive agents improves the prognosis of the disease, ocular morbidity is still well recognized. Clinicians should consider a differential diagnosis of GPA in patients with inflammatory choroidal tumors

Soluble FcγRIIIaMφ Levels in Plasma Correlate with Carotid Maximum Intima-Media Thickness (IMT) in Subjects Undergoing an Annual Medical Checkup

Macrophages play a major role in the development of vascular lesions in atherogenesis. The cells express FcγRIIIa (CD16) identical to that in NK cells, but with a cell type-specific glycosylation, and these soluble forms (sFcγRIIIa) are present in plasma. We measured sFcγRIIIaMφ derived from macrophages in plasma from subjects undergoing an annual medical checkup. The levels of sFcγRIIIaMφ increased with age, and correlated positively with body mass index, blood pressure, LDL cholesterol to HDL cholesterol ratio, triglycerides, hemoglobin A1c, and creatinine, but negatively with HDL-cholesterol levels. The sFcγRIIIaMφ levels were related to the number of risk factors for atherosclerosis: such as aging, current smoking, diabetes, hypertension, hyper-LDL-cholesterolemia, hypo-HDL-cholesterolemia, and family history of atherosclerotic diseases. In addition, the sFcγRIIIaMφ levels were correlated with carotid maximum intima-media thickness (IMT). These findings indicate the macrophages are activated during the incipient stage of atherosclerosis, and suggest sFcγRIIIaMφ may be used as a predictive marker for atherosclerosis