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Niobium thin films are key components of superconducting microwave resonators. Interest in these devices has increased dramatically because of their application in quantum systems. Despite tremendous effort to improve their performance, loss mechanisms are still not well understood. Nb/substrate and Nb/air interfaces are likely culprits in contributing to decoherence and ultimately limiting the performance of superconducting devices. Here, we investigate the Nb/substrate interface by studying the effect of hydrogen-passivated H:Si(111) substrates on the local superconducting properties of ∼40 nm thick Nb films compared to Nb films grown on typical Si(001) substrates. Specifically, low-temperature scanning tunneling microscopy and spectroscopy are employed to compare nanoscale material properties. The atomically flat monohydride H:Si(111) substrates are found to yield a smoother and less defective interface with the Nb film. Correspondingly, the Nb films grown on H:Si(111) substrates present more uniform superconducting properties and exhibit less quasiparticle broadening.

AISI 304 steel was studied in the field of hydrogen storage. Specifically, the hydrogen quantity by electrolytic charge at a variation time for a predetermined current density was measured. Then this quantity was compared to the variation of mechanical properties at the same charge time. Finally, a parallel was drawn between FCC and BCC hydrogenated lattices.

Low-density Polyethylene (PE) were synthesized with poly[butyl methacrylate (B)-co-styrene (S)], poly(dodecyl methacrylate(D)-co-styrene] and poly(ethyl hexyl methacrylate (EH)-co-styrene] copolymers in order to obtain IPN-like networks. Different S/methacrylate copolymer molar ratios going from 0/100 up to 60/40, a molar percentage of 1.0% of 1,4-butanedioldimethacrylate (b) and 3 wt% of 2,5-dimethyl-2,5-di-(tert-butyl peroxy) hexane (Luperox 101) were used. The samples were analyzed at RT by WAXS, swelling in CCl4 and mechanical tensile tests. Dynamic-mechanical tests and optical investigations were performed in a temperature range between RT and 180°C. All the IPN types showed optical reversible transitions (transparency-to opacity and vice versa) with varying temperature, due to a refractive index (RI) matching-mismatching of PE and copolymer networks. The copolymer chemical nature as well as its composition affected sensitively most of the analyzed properties.

Studi sulla Formazione

716 PROGNOSTIC GENE-EXPRESSION SIGNATURE FOR HEPATITIS C-RELATED EARLY-STAGE LIVER CIRRHOSIS Y. Hoshida, A. Villanueva, A. Sangiovanni, M. Sole, C. Hur, K.L. Andersson, R.T. Chung, J. Gould, K. Kojima, S. Gupta, B. Taylor, A. Crenshaw, S. Gabriel, B. Minguez, M. Iavarone, S.L. Friedman, M. Colombo, J.M. Llovet, T. Golub. Broad Institute of Harvard and MIT, Dana-Farber Cancer Institute, Boston, MA, USA; Laboratori de Reserca Translacional d’Oncoloǵia Hepatica, IDIBAPS, Ciberehd, Hospital Clinic, Barcelona, Spain; Division of Gastroenterology, Fondazione Ca Granda IRCCS Ospedale Maggiore Policlinico, Universita degli Studi di Milano, Milan, Italy; Dept. of Pathology, Hospital Cĺinic, Barcelona, Spain; Massachusetts General Hospital-Harvard Medical School, Boston, MA, USA; Liver Unit, Department of Medicine, Hospital Universitari Vall d’Hebron, Barcelona, Spain; Department of Liver Diseases, Mount Sinai School of Medicine, New York, NY, USA E-mail: hoshida@broadinstitute.org

reduced to a thin shell; a moderate dilatation of the Introduction collecting system was demonstrated in the left kidney. After contrast media injection, the right kidney was Renal tuberculosis is not mentioned in the current not visualized, while the left kidney revealed pyelocalliterature among the various causes of acute renal iectasis secondary to the presence of a stricture at the failure (ARF) [1,2]. We report for the first time that level of the pyeloureteral junction, which was associobstructive ARF may be caused by tuberculosis and ated with a moderately restricted left ureter (Figure 1). reversed by medical therapy. There were no genitourinary calcifications. The right kidney was removed with no change in the renal function. The histopathological examination led to the Case report diagnosis of tuberculous pyonephrosis. We started treatment with isoniazid (300 mg/day), rifampicin A 46-year-old woman was admitted with epigastric (600 mg/day), and ethambutol (400 mg/day). Six pain and dyspepsia. She reported symptoms of gastmonths of this therapy progressively reduced the values ritis, occasionally treated with anti-H2 drugs. Past of plasma creatinine and urea levels to 106 mmol/l and medical history included insulin-dependent diabetes 6.5 mmol/l respectively, associated with improvement mellitus for about 20 years associated with marked of creatinine clearance (71 ml/min) and urinary abnordiabetic retinopathy, slight reduction of renal function malities (5 red blood cells and 5 white blood cells per (plasma creatinine level of 106 mmol/l, creatinine clearhigh-power field). The renal echography demonstrated ance of 69 ml/min), proteinuria less than 1 g/day, complete remission of the obstruction. moderate erythrocyturia and leukocyturia. On admission, no other symptom was detected and gastroprotective drugs relieved the gastric pain. The biochemical Comment assessment showed increased plasma creatinine (177 mmol/l ) with a creatinine clearance of 28 ml/min, urea (11.5 mmol/l ), glycaemia (5.5 mmol/l ), and diurThis case depicts renal tuberculosis (TB) as a cause of esis (900 ml/day), with normal blood pressure obstructive ARF. In our patient the lack of a previous (130/80 mmHg). Urinalysis revealed erthrocyturia (10 diagnosis of renal TB was probably due both to the cells per high-power field ) and leukocyturia (10 cells absence of urinary and systemic symptoms of TB and per high-power field) with a pH of 6.0 and a specific to the urinary and renal function abnormalities that gravity of 1.015. An increase in erythrocyte sedimentacould be attributed to the long-term diabetic nephrotion rate (56 at the 1st hour) was associated with a pathy. Indeed, more insights were attained only after moderate degree of anaemia (Hct=35%). All other the incidental discovery of ARF. The unilateral ureteral examinations including white blood-cell count and stricture, which was probably secondary to the presence chest radiography were within normal limits. of mucosal tuberculous nodules at the level of the Prerenal and toxic causes of renal failure were ureteropelvic junction, and the combined absence of excluded by careful anamnesis and clinical and laboratcontralateral renal function, accounted for the developory assessment. To investigate postrenal causes of ment of ARF. The short-term antituberculous therapy impaired renal function, the patient underwent sequenled to the remission of ARF. Notably, no previous tial radiographic examinations (echography, urograreports of similar cases appear in the current literature. phy, and computerized tomography). These The clinical manifestations of renal TB are generally examinations revealed a right kidney of increased size unilateral and involve about 3% of all TB patients [3]. with gross cavities in which the renal parenchyma was Bilateral advanced renal TB, similar to the case presented, is considered as a unusual cause of chronic renal failure [4], and it is not even mentioned among Correspondence and o print requests to: Prof. Giuseppe Conte, the various causes of ARF [1,2]. It is important to Division of Nephrology, Second University of Naples, Via Luigi Caldieri 10, 80127 Naples, Italy. underline that TB is a re-emergent infection. Indeed

We report on fabrication of Y/sub 1/Nd/sub x/Ba/sub 2-x/Cu/sub 3/O/sub 7-/spl delta// and Nd/sub 1+x/Ba/sub 2-x/Cu/sub 3/O/sub 7-/spl delta// thin films deposited by high oxygen pressure dc sputtering. The structural properties are investigated by X-ray diffraction while Scanning Tunneling Microscopy (STM) has been used to determine the surface morphology. The critical temperature and the critical current density are obtained by transport and inductive measurements. The microwave properties have been studied at 19.8 GHz by a dielectric resonator technique. For both compounds highly epitaxial c-axis thin films are routinely obtained on SrTiO/sub 3/ and LaAlO/sub 3/ substrates. Depending on the deposition conditions, films characterized by surface resistance comparable of even better than YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// have been obtained, with a substantial improvement of the structural properties and of the surface morphology. The role played by the Nd/Ba substitution on the growth and on the superconducting properties is discussed.

The design and realization of a simple and reliable convertible diode/magnetron deposition system allowing the in situ production of both high-T-c superconducting oxide films and low-T-c superconducting metallic films is presented. The ability to produce high-quality double-sided in situ films with uniform characteristics over 2 " diameter targets is demonstrated. This apparatus can represent a valid alternative to more sophisticated, less flexible deposition systems and is well suited for application in the large-scale production of superconducting filters for wireless communications.

We have studied the effect of Nd/Ba substitution on the superconducting properties of R 1 (Nd x Ba 2− x )Cu 3 O 7 (R=Nd, Y) thin films by using microwave penetration depth and surface resistance measurements. Data on samples characterised by a Nd-excess of 4–5% have been collected by using a microstrip resonator at frequencies of 1.44 and 9.7 GHz and a symmetric dielectric resonator technique in TE 0 1 1 mode at 19.8 GHz. A quadratic bT 2 low temperature dependence of the penetration depth is observed for the Nd-rich samples, with the coefficient b decreasing with the frequency. The data can be reasonably explained in a d-wave framework supposing that Nd at Ba site behaves, both in Nd 1+ x Ba 2− x Cu 3 O 7 and Y 1 (Nd x Ba 2− x )Cu 3 O 7 , as a resonant impurity, as confirmed by scanning tunnelling spectroscopy. The changes of the temperature dependence of the penetration depth with the frequency can be explained with a two fluid approach taking into account the frequency dependence of the complex conductivity.

LuNi 2 B 2 C films have been prepared by a Pulsed Laser Deposition technique. The deposition parameters have been optimized to reach good superconducting, structural and morphological properties with high reliability. In order to deposit different patterned layers for in-situ junctions production, a special set-up for the in situ interchanging of shadow masks has been developed. We studied the growth of different materials to be used as barrier layers. New results on the temperature dependence of the LuNi 2 B 2 C gap using S/N contact junctions are presented and discussed.

The properties of high quality single side and double side YBa 2 Cu 2 O 7-δ (YBCO) thin films deposited on LaA1O 3 substrates by pure oxygen d.c. sputtering are reported. The single side films are highly c -axis oriented with their a (or b) axis parallel to that of the substrate. The critical temperature is higher than 91 K with transition width less than 0.5 K, while the critical current density Jc is higher than 3 MA/cm2 at 77 K. The best double side samples exhibit no appreciable differences in the superconducting properties of the films deposited on the two different sides. X-ray analyses show in both cases highly c-axis oriented thin films with comparable values of the c -axis length (1.169 nm). The microwave properties are tested by a microstrip resonator technique. The surface resistance is lower than 80 μΩ at 77 K and f=5.4 GHz while the penetration depth at low temperature is in the range 150-200 nm.

Rare-earth borocarbide superconductors have recently attracted the attention of researchers because of their intriguing superconducting and magnetic properties. In the present paper we report on the in situ synthesis of high-quality thin films of these materials (RE = Y, Er) using planar magnetron sputtering. Low-temperature STM tunnelling investigations were performed on films and single crystals. The STM results, together with d.c. transport measurements, give strong evidence of the weak-coupling BCS nature of these compounds. A discussion of the magnetic vortex structure and of the interplay of superconductivity and magnetism is also included.