We have studied the electrical transport properties of individual single-crystalline IrO(2) nanorods prepared by the metal-organic chemical vapour deposition method. With the help of the standard electron-beam lithographic technique, individual nanorods are contacted by Cr/Au submicron electrodes from above. Utilizing two-probe, three-probe and four-probe measurement configurations, not only the intrinsic electrical transport properties of the individual nanorods but also the electronic contact resistances, R(c)(T), have been determined from 300 K down to liquid-helium temperatures. Our measured resistivity behaviour of the nanorods is in close agreement with the current theoretical understanding of this rutile material. On the other hand, we found that the temperature behaviour of the electronic contact resistance obeys the law [Formula: see text] over an extremely wide temperature range, from approximately 100 K down to liquid-helium temperatures. This latter conduction process is ascribed to the hopping of electrons through nanoscale Cr granules and/or an amorphous coating incidentally formed at the interface between the submicron Cr/Au electrode and the nanorod.

We have measured the tunneling differential conductances, G͑V͒, of four Al/ AlO x / Cr planar tunnel junctions as well as the conductivities, ͑T͒, of the Cr electrodes at liquid-helium temperatures. The Cr electrodes were made to be granular with dimensionless intergrain tunneling conductance spanning from g Ӎ 1 to g ӷ 1, and the dimensionality of the granular array d = 3. For the samples with g ӷ 1, we found that the measured G͑V͒ curves display large zero-bias singularities which obey a ln V law at low bias voltages ͑Շ a few millielectron volt͒ while crossing over to a ͱ V law at high bias voltages. Simultaneously, the conductivities of the Cr electrodes reveal ln T dependence below a characteristic temperature. These results are explained in terms of the recent theory of granular metals. In a sample with g Ӎ 1, in addition to the conductivity dependence ϰ ln T, we observed a universal scaling behavior of the normalized differential conductance ͓G͑V , T͒ − G͑0,T͔͒ / ͱ T with the combined parameter ͱ e͉V͉ / k B T in a wide temperature interval of 2.5-32 K. This resultis not yet understood.

The purpose of this study was to review the radiographs of symptomatic femoral head osteonecrosis in patients with systemic lupus erythematosus (SLE) and to assess the results of treatment using free vascularised fibular grafting. We retrospectively reviewed 50 patients (80 hips) with SLE who underwent free vascularised fibular grafting for osteonecrosis of the femoral head. All patients were followed up for at least 2 or more years (average, 4.3 years). The mean Harris hip score improved from 72 to 88. At the latest follow-up, we found improved or unchanged radiographs in 12 of initially Stage II hips and in 60 of 64 Stage III or IV hips. No hips failed treatment and underwent total hip arthroplasty. The data suggest that free vascularised fibular grafting was successful in maintaining joint function and in delaying the need for joint replacement procedure.

In order to determine the frequency of SARS-CoV-2 placental and fetal involvements, we analyzed placentas of 197 women positive for infection at delivery and fetal tissues in cases of pregnancy loss in women positive by SARS-CoV-2 PCR (N = 2) and COVID-19 serology (N = 4), using in situ hybridization (ISH), immunohistochemistry (IHC) and, in selected cases, RT-PCR of tissue homogenates. The virus was identified in situ, accompanied by intervillositis, in 2 of 197 placentas (1.02%). In three more cases, SARS-CoV-2 was detected by tissue PCR without in situ localization and placental inflammation. There were no maternal mortality or association of placental infection with the clinical severity of COVID-19. All tested neonates born to SARS-CoV-2-positive women (N = 172) were negative for the virus. There were three pregnancy losses among 197 infected women and in two cases available fetal tissues were negative for SARS-CoV-2. In one of four fetal autopsies performed in women with positive COVID-19 serology, the mother-to-child transmission (MTCT) could be inferred based on positive SARS-CoV-2 nucleocapsid IHC in fetal pulmonary endothelium. Placental involvement by SARS-CoV-2 is rare, but may be underestimated due to its transient nature. MTCT is even rarer, supporting the protective role of placenta in SARS-CoV-2 infection.