High-performance Fe(Se,Te) films on chemical CeO2-based buffer layers.

The fabrication of a Fe-based coated conductor (CC) becomes possible when Fe(Se,Te) is grown as an epitaxial film on a metallic oriented substrate. Thanks to the material's low structural anisotropy, less strict requirements on the template microstructure allow for the design of a simplified CC architecture with respect to the REBCO multi-layered layout. This design, though, still requires a buffer layer to promote the oriented growth of the superconducting film and avoid diffusion from the metallic template. In this work, Fe(Se,Te) films are grown on chemically-deposited, CeO2-based buffer layers via pulsed laser deposition, and excellent properties are obtained when a Fe(Se,Te) seed layer is used. Among all the employed characterization techniques, transmission electron microscopy proved essential to determine the actual effect of the seed layer on the final film properties. Also, systematic investigation of the full current transport properties J(θ, H, T) is carried out: Fe(Se,Te) samples are obtained with sharp superconducting transitions around 16 K and critical current densities exceeding 1 MA cm-2 at 4.2 K in self-field. The in-field and angular behavior of the sample are in line with data from the literature. These results are the demonstration of the feasibility of a Fe-based CC, with all the relative advantages concerning process simplification and cost reduction.

Mn-induced Fermi-surface reconstruction in the SmFeAsO parent compound.

The electronic ground state of iron-based materials is unusually sensitive to electronic correlations. Among others, its delicate balance is profoundly affected by the insertion of magnetic impurities in the FeAs layers. Here, we address the effects of Fe-to-Mn substitution in the non-superconducting Sm-1111 pnictide parent compound via a comparative study of SmFe[Formula: see text]Mn[Formula: see text]AsO samples with [Formula: see text] 0.05 and 0.10. Magnetization, Hall effect, and muon-spin spectroscopy data provide a coherent picture, indicating a weakening of the commensurate Fe spin-density-wave (SDW) order, as shown by the lowering of the SDW transition temperature [Formula: see text] with increasing Mn content, and the unexpected appearance of another magnetic order, occurring at [Formula: see text] and 20 K for [Formula: see text] and 0.10, respectively. We attribute the new magnetic transition at [Formula: see text], occurring well inside the SDW phase, to a reorganization of the Fermi surface due to Fe-to-Mn substitutions. These give rise to enhanced magnetic fluctuations along the incommensurate wavevector [Formula: see text], further increased by the RKKY interactions among Mn impurities.

In-plane and out-of-plane properties of a BaFe2As2 single crystal.

Anisotropy of transport and magnetic properties of parent compounds of iron based superconductors is a key ingredient of superconductivity. In this work, we investigate in-plane and out-of-plane properties, namely thermal, electric, thermoelectric transport and magnetic susceptibility in a high quality BaFe2As2 single crystal of the 122 parent compound, using a combined experimental and theoretical approach. Combining the ab initio calculation of the band structure and the measured in-plane and out-of-plane resistivity, we evaluate the scattering rates which turn out to be strongly anisotropic and determined by spin excitations in the antiferromagnetic state. The observed anisotropy of thermal conductivity is discussed in terms of anisotropy of sound velocities which we estimate to be [Formula: see text]. Remarkably, we find that thermal conductivity is characterized by a sizeable electronic contribution at low temperature, which is ascribed to the high purity of our crystal.

Colonoscopic excision of large and giant colorectal polyps. Technical implications and results over eight years.

Large polyps are sessile or pedunculated lesions that are larger than or equal to 3 cm in size. Sixty-six colonoscopic piecemeal excisions of large pedunculated and sessile polyps (75 percent of 88 recognized large polyps) were performed over eight years. The macroscopic feature of the lesions and the result of an extensive snare biopsy were the deciding factors for endoscopic as opposed to surgical removal. Only three complications (4.5 percent) were recorded (two hemorrhages and one colonic wall burn syndrome), none of which required surgery. Fifty patients with 52 adenomatous lesions had colonoscopic follow-up (range, 3 to 85 months). Of 36 sessile adenomas, two cases of residual (5.5 percent) and four of recurrent disease (11 percent) were observed. Colonoscopic removal is an alternative to local surgical excision of large benign colorectal polyps, and often can be an alternative method to elective colectomy in elderly and high-risk patients.

Foreign bodies of the biliary tract. Endoscopic management.

In the period 1978-1984, 23 patients underwent endoscopic intervention for foreign bodies of the biliary tract. The patients are subdivided into three groups: the first group consists of 11 cases in which the foreign bodies were suture threads, either simple or as a nidus for gallstones; the second group consists of six patients with a sump syndrome of the biliary tract; the third group includes six patients who retained drainage tubes or stents after a biliary tract operation. In our series, endoscopic extraction was performed as a first-choice procedure. The high success rate may favor endoscopy as a low-morbidity, low-mortality approach and as an alternative to a relaparotomy.

Endoscopic injection sclerotherapy of esophageal varices. Considerations on the first 85 patients.

Eighty-five consecutive cases of esophageal varices treated by endoscopic sclerotherapy are analyzed retrospectively. Most of these cases (84.7%) were done in emergency in patients (60) with poor liver function. Bleeding was stopped in 94.4% of cases but 22% of them had at least one rebleeding episode. Only a few and minor complications were observed. The safety and the immediate good results obtained by the procedure recommend it as a primary measure in bleeding esophageal varices. Moreover the actual role of endoscopic sclerotherapy as an elective or prophylactic procedure in the treatment of hemorrhage from esophageal varices, is discussed.

Gastrointestinal hemorrhage from an aortoduodenal fistula: endoscopic considerations.

A case of gastrointestinal hemorrhage from a secondary aortoduodenal fistula, treated with removal of the prosthesis and reconstruction of duodenal and aortic wall, is reported. The endoscopic findings that provided a preoperative diagnosis are discussed.