Electron-phonon superconductivity in C-doped topological nodal-line semimetal Zr5Pt3: a muon spin rotation and relaxation (µSR) study.

In the present work, we demonstrate that C-doped Zr5Pt3is an electron-phonon superconductor (with critical temperatureTC= 3.8 K) with a nonsymmorphic topological Dirac nodal-line semimetal state, which we report here for the first time. The superconducting properties of Zr5Pt3C0.5have been investigated by means of magnetization, resistivity, specific heat, and muon spin rotation and relaxation (µSR) measurements. We find that at low temperatures, the depolarization rate is almost constant and it can be well described by a single-bands-wave model with a superconducting gap of 2Δ(0)/kBTC= 3.84, somewhat higher than the value of BCS theory. From the transverse field µSR analysis, we estimate the London penetration depthλL= 469 nm, superconducting carrier densityns= 1.83 × 1026 m-3, and effective massm* = 1.428me. The zero field µSR confirms the absence of any spontaneous magnetic field in the superconducting ground state. In order to gain additional insights into the electronic ground state of C-doped Zr5Pt3, we also performed first-principles calculations within the framework of density functional theory (DFT). The observed homogenous electronic character of the Fermi surface as well as the mutual decrease ofTCand density of states at the Fermi level are consistent with the experimental findings of this study. However, the band structure reveals the presence of robust, gapless fourfold-degenerate nodal lines protected by 63screw rotations and glide mirror planes. Therefore, Zr5Pt3represents a novel, unprecedented condensed matter system to investigate the intricate interplay between superconductivity and topology.

Evidence of a Nodal Line in the Superconducting Gap Symmetry of Noncentrosymmetric ThCoC_{2}.

The newly discovered noncentrosymmetric superconductor ThCoC_{2} exhibits numerous types of unconventional behavior in the field dependent heat capacity data. Here we present the first measurement of the gap symmetry of ThCoC_{2} by muon spin rotation and relaxation (µSR) measurements. The temperature dependence of the magnetic penetration depth measured using the transverse field µSR experiment reveals the evidence of a nodal pairing symmetry. To understand this finding, we carry out calculations of the superconducting pairing eigenvalue and eigenfunction (pairing symmetry) due to the spin-fluctuation mechanism by directly implementing the ab initio band structures. We find that the system possesses a single Fermi surface with considerable three dimensionality and a strong nesting along the k_{z} direction. Such nesting promotes a superconducting state with a cosk_{z}-like pairing symmetry with a prominent nodal line on the k_{z}=±π/2 plane. The result agrees well with the experimental data.

Peripheral nerve surgery: the role of high-resolution MR neurography.

High-resolution MRN is becoming increasingly available due to recent technical advancements, including higher magnetic field strengths (eg, 3T), 3D image acquisition, evolution of novel fat-suppression methods, and improved coil design. This review describes the MRN techniques for obtaining high-quality images of the peripheral nerves and their small branches and imaging findings in normal as well as injured nerves with relevant intraoperative correlations. Various microsurgical techniques in peripheral nerves, such as neurolysis, nerve repairs by using nerve grafts, and conduits are discussed, and MRN findings of surgically treated nerves are demonstrated.

Differential effects of glycosylated and non-glycosylated porcine prolactin on estradiol and progesterone secretion by rat granulosa cells in culture.

BACKGROUND: The objective was to better understand the interactions between prolactin and ovarian function. METHODS: The effects of two variants of porcine prolactin (pPRL) on estradiol (E2) and progesterone (P4) production by rat granulosa cells in culture were studied using granulosa cells obtained from large preovulatory follicles of pregnant mare serum gonadotropin (PMSG)-treated immature Sprague-Dawley rats. Cultures were performed in the absence or presence of hCG (0.1 IU/ml) and different concentrations of either glycosylated and non-glycosylated (g-pPRL and ng-pPRL, respectively) pPRL. RESULTS: Dose-response studies showed that maximal stimulation occurred in all instances with g-pPRL at the dose of 10 ng/mL during the 72-h treatment period. In the case of E2, the maximal response was obtained in hCG-stimulated cultures, whereas the response of P4 was higher in cultures stimulated with g-pPRL in the absence of hCG. In a similar manner, the non-glycosylated form of pPRL increased, although to a lesser extent, the secretion of P4 only in those cultures incubated in the absence of hCG. In contrast to these observations, ng-pPRL was about twice as active than the glycosylated form on the stimulation of growth of Nb2 lymphoma cells. CONCLUSIONS: These data point out that glycosylation is involved in the differential effects of pPRL on ovarian steroidogenesis and support the role of carbohydrates in the structural-functional polymorphic nature of the hormone.

Modulation of stimulatory action of follicle stimulating hormone (FSH) and inhibitory action of epidermal growth factor (EGF) on aromatase activity in Sertoli cells by calcium.

Aromatization of testosterone by cultured Sertoli cells isolated from immature rats was stimulated more than 7-fold by follicle stimulating hormone (FSH) or dcAMP. The effects of FSH and dcAMP could be partly inhibited by epidermal growth factor (EGF) in a dose-dependent manner (ID500.5 nM). The phorbol ester 4 beta-phorbol-12-myristate-13-acetate (PMA) could also inhibit aromatase activity in a fashion similar to EGF. When 3 mM EGTA was present in the culture medium, the inhibitory effect of EGF was abolished but the stimulatory effect of FSH or dcAMP was magnified. These results suggest that EGF exerts a negative control on aromatase via calcium and protein kinase C. The abolishment of the inhibitory effect of EGF and the enhancement of the stimulatory effect of FSH or dcAMP by a calcium deficiency may be an indication that growth factors produced by Sertoli cells negatively controls FSH-induced responses in an autocrine fashion.

Epidermal growth factor stimulates lactate production and inhibits aromatization in cultured Sertoli cells from immature rats.

The addition of epidermal growth factor (EGF) at nanomolar concentrations to cultures of Sertoli cells from 16-day-old rats induced more than a 2-fold stimulation of lactate production after 12 h of incubation. The effects of EGF, insulin and FSH on lactate production were very similar and the concentrations that produced half maximal stimulation were 11, 22 and 25 ng/ml or, in molar terms, 1.8, 3.5 and 0.6 nM for EGF, insulin and FSH, respectively. No synergistic or additive effects of these hormones on lactate production could be demonstrated. In contrast, EGF inhibited FSH-stimulated oestradiol synthesis by more than 50%. Insulin had no effect on FSH-stimulated aromatization.

Chromatographic pattern of circulating prolactin in ovulatory hyperprolactinemia.

Hyperprolactinemia is a major cause of anovulation and female infertility. However, we found 22 hyperprolactinemic patients with preserved ovarian function as assessed by midluteal plasma progesterone levels greater than 7 ng/ml. We performed a gel chromatography on the plasma of six of those patients to study the circulating pattern of prolactin (PRL). In all six patients we found that the vast majority of circulating PRL corresponds to big,big and big PRL, with only a small proportion of monomeric biologically active PRL. This finding might explain the preserved luteal function in those women and might have therapeutic implications.