Publisher Correction: Electronic structure of the parent compound of superconducting infinite-layer nickelates.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Electronic structure of the parent compound of superconducting infinite-layer nickelates.

The search continues for nickel oxide-based materials with electronic properties similar to cuprate high-temperature superconductors1-10. The recent discovery of superconductivity in the doped infinite-layer nickelate NdNiO2 (refs. 11,12) has strengthened these efforts. Here, we use X-ray spectroscopy and density functional theory to show that the electronic structure of LaNiO2 and NdNiO2, while similar to the cuprates, includes significant distinctions. Unlike cuprates, the rare-earth spacer layer in the infinite-layer nickelate supports a weakly interacting three-dimensional 5d metallic state, which hybridizes with a quasi-two-dimensional, strongly correlated state with [Formula: see text] symmetry in the NiO2 layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare-earth intermetallics13-15, which are well known for heavy fermion behaviour, where the NiO2 correlated layers play an analogous role to the 4f states in rare-earth heavy fermion compounds. This Kondo- or Anderson-lattice-like 'oxide-intermetallic' replaces the Mott insulator as the reference state from which superconductivity emerges upon doping.

Two-dimensional normal-state quantum oscillations in a superconducting heterostructure.

Semiconductor heterostructures provide an ideal platform for studying high-mobility, low-density electrons in reduced dimensions. The realization of superconductivity in heavily doped diamond, silicon, silicon carbide and germanium suggests that Cooper pairs eventually may be directly incorporated in semiconductor heterostructures, but these newly discovered superconductors are currently limited by their extremely large electronic disorder. Similarly, the electron mean free path in low-dimensional superconducting thin films is usually limited by interface scattering, in single-crystal or polycrystalline samples, or atomic-scale disorder, in amorphous materials, confining these examples to the extreme 'dirty limit'. Here we report the fabrication of a high-quality superconducting layer within a thin-film heterostructure based on SrTiO(3) (the first known superconducting semiconductor). By selectively doping a narrow region of SrTiO(3) with the electron-donor niobium, we form a superconductor that is two-dimensional, as probed by the anisotropy of the upper critical magnetic field. Unlike in previous examples, however, the electron mobility is high enough that the normal-state resistance exhibits Shubnikov-de Haas oscillations that scale with the perpendicular field, indicating two-dimensional states. These results suggest that delta-doped SrTiO(3) provides a model system in which to explore the quantum transport and interplay of both superconducting and normal electrons. They also demonstrate that high-quality complex oxide heterostructures can maintain electron coherence on the macroscopic scales probed by transport, as well as on the microscopic scales demonstrated previously.

Titanium dxy ferromagnetism at the LaAlO3/SrTiO3 interface.

A number of recent transport and magnetization studies have shown signs of ferromagnetism in the LaAlO3/SrTiO3 heterostructure, an unexpected property with no bulk analogue in the constituent materials. However, no experiment thus far has provided direct information on the host of the magnetism. Here we report spectroscopic investigations of the magnetism using element-specific techniques, including X-ray magnetic circular dichroism and X-ray absorption spectroscopy, along with corresponding model calculations. We find direct evidence for in-plane ferromagnetic order at the interface, with Ti(3+) character in the dxy orbital of the anisotropic t2g band. These findings establish a striking example of emergent phenomena at oxide interfaces.

Subband structure of a two-dimensional electron gas formed at the polar surface of the strong spin-orbit perovskite KTaO3.

We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO3. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, our measurements provide a direct upper bound for the potential Rashba spin splitting of only Δk(parallel)}~0.02 Å(-1) at the Fermi level. The polar nature of the KTaO3(100) surface appears to help mediate the formation of the 2DEG as compared to nonpolar SrTiO3(100).

Fermi surface and superconductivity in low-density high-mobility δ-doped SrTiO3.

The electronic structure of low-density n-type SrTiO3 δ-doped heterostructures is investigated by angular dependent Shubnikov-de Haas oscillations. In addition to a controllable crossover from a three- to two-dimensional Fermi surface, clear beating patterns for decreasing dopant layer thicknesses are found. These indicate the lifting of the degeneracy of the conduction band due to subband quantization in the two-dimensional limit. Analysis of the temperature-dependent oscillations shows that similar effective masses are found for all components, associated with the splitting of the light electron pocket. The dimensionality crossover in the superconducting state is found to be distinct from the normal state, resulting in a rich phase diagram as a function of dopant layer thickness.

Dominant mobility modulation by the electric field effect at the LaAlO3/SrTiO3 interface.

Caviglia et al. [Nature (London) 456, 624 (2008)] have found that the superconducting LaAlO3/SrTiO3 interface can be gate modulated. A central issue is to determine the principal effect of the applied electric field. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost 5 times that of the sheet carrier density. Furthermore, superconductivity can be suppressed at both positive and negative gate bias. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition.

Dielectric collapse at the LaAlO3/SrTiO3 (001) heterointerface under applied electric field.

The fascinating interfacial transport properties at the LaAlO3/SrTiO3 heterointerface have led to intense investigations of this oxide system. Exploiting the large dielectric constant of SrTiO3 at low temperatures, tunability in the interfacial conductivity over a wide range has been demonstrated using a back-gate device geometry. In order to understand the effect of back-gating, it is crucial to assess the interface band structure and its evolution with external bias. In this study, we report measurements of the gate-bias dependent interface band alignment, especially the confining potential profile, at the conducting LaAlO3/SrTiO3 (001) heterointerface using soft and hard x-ray photoemission spectroscopy in conjunction with detailed model simulations. Depth-profiling analysis incorporating the electric field dependent dielectric constant in SrTiO3 reveals that a significant potential drop on the SrTiO3 side of the interface occurs within ~2 nm of the interface under negative gate-bias. These results demonstrate gate control of the collapse of the dielectric permittivity at the interface, and explain the dramatic loss of electron mobility with back-gate depletion.

[The causes and timing of reoperation for coronary artery disease].

In eight hundred and sixteen consecutive patients undergoing coronary artery bypass grafting (CABG) within the past 19 years (1974 to 1993), repeated CABG were performed on 12 patients (1.47%). The main reasons for repeated CABG were graft failure (GF), progression of native disease (NP) and incomplete revascularization (IR). The incidence of GF only and GF combined NP were high either within a half year or around 5 years after CABG. When the recurrence of angina is noted after CABG, the catheter intervention should be chosen at first but the reoperation should be done not so late. Although all patients survived from reoperation, three patients continued to have mild angina pectories. If a reoperation is inevitable, maximum utilization of arterial graft and accomplishment of complete revascularization are emphasized.

[Coronary artery bypass utilizing vein grafts: why didn't we use an arterial graft?].

Internal thoracic artery (ITA) grafts for coronary artery bypass grafting (CABG) are superior to SVG in the long-term patency and survival. In spite of our effort to utilize ITA whenever possible, we still have some cases which have to receive only vein grafts. Among the consecutive 201 patients undergoing CABG in the past three years, 32 patients (16%) received only vein grafts. We compared these patients (SVG group) with those who received ITA grafts (ITA group). The SVG group consisted of all emergency cases and many cases with single and double vessel disease. In the SVG group, perioperative use of IABP was more frequent and operative mortality was higher, although the number of grafts was fewer (2.66 vs 3.61) and aortic cross clamping time was shorter in this group. Main reasons for selecting only vein grafts were emergency surgery, inadvertent injury of ITA, inadequate ITA free flow etc. Technical refinement in the preparation of ITA is important to make possible wider application of arterial grafts for CABG.

Coronary artery disease investigated using 99mTc-tetrofosmin myocardial SPECT.

BACKGROUND: Coronary artery disease can be diagnosed from stress and delayed images of myocardial single photon emission computed tomography (SPECT) using technetium-99 m-tetrofosmin (TcTF). However, the negative predictive value of stress SPECT images after a single injection of a low tracer dose remains unknown. Thus, the present study investigates whether normal stress SPECT results predict event-free survival. MATERIALS AND METHODS: We screened 302 consecutive patients who were randomly assigned to two groups for myocardial ischaemia using either stress SPECT with a low dose of TcTF (296 MBq, TcTF group, n = 150) or stress together with rest SPECT using thallium(201) chloride (TlCl, 111 MBq; TlCl group, n = 152) as the tracer. A total of 80 patients with abnormal SPECT findings were excluded and the remaining 222 with normal results (age, 66.5 +/- 0.7 years; TcTF/TlCl, 112/110) were enrolled in the present study and followed up for 401 +/- 9 days, with the endpoint being ischaemic cardiac events. RESULTS: The incidence of cardiac events did not differ between the two groups (0.9% and 0.0% in TcTF and TlCl groups, respectively). The cost and duration of TcTF and TlCl SPECT examinations were about 425 and 603 Euros and 50 and 280 min, respectively. CONCLUSIONS: The negative predictive values of stress SPECT using a low dose of TcTF and of combined stress and rest SPECT using TlCl did not differ and both were clinically acceptable. Thus, stress SPECT using low dose TcTF is useful in screening patients for myocardial ischaemia.

[Reevaluation of recalled infants by neonatal mass screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Diagnostic value of pregnanetriolone in a single urine specimen using glass capillary gas chromatography].

To establish a detailed reevaluation system for infants who were recalled by a neonatal mass screening for congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, pregnanetriol (PT) and pregnanetriolone (PTL) in a single urine specimen combined with plasma 17 alpha-hydroxyprogesterone (17-OHP) and 21-deoxycortisol (21-DOF) were determined by a simple method using glass capillary gas chromatography. A pilot study of neonatal mass screening for CAH with a determination of "disc 17-OHP" value in dried blood on filter paper was carried out in Western Shizuoka Prefecture. During the study period (32 months), 37472 neonates were determined by mass screening, and 362 neonates proved to be abnormal candidates who needed further evaluations. From out of these candidates, 262 neonates responded with recall and were studied. Amongst these 262 neonates, 241 neonates visited directly our outpatient clinic at Hamamatsu University Hospital. The reevaluation conducted at our clinic included a physical examination, detailed family history, measurement of serum electrolytes, disc 17-OHP, plasma 17-OHP and 21-DOF values, and PT and PTL in a single urine specimen. Consequently, 3 neonates appeared to be patients with CAH. Two of them were the salt-losing type and the other was the simple virilizing type. The rest of the candidates who received reevaluation were finally decided to be healthy neonates, indicating false positivity by mass screening. Compared to the candidates who showed false positivity in the mass screening, the CAH patients had an apparently high urinary PT and PTL titer of ten or one hundred fold. Additionally, despite corticosteroid treatment in one case, significantly elevated levels of PT and PTL were detected. To assay PTL was a more reliable parameter for the detection of CAH and for following up the candidates because PTL was not detectable in 63.3% of the false positive cases, suggesting that PTL was less likely to indicate false positive cases. PTL was detected at more than 0.01 microgram/ml urine in 19.4% of false positive cases, however, no case showed further elevation of PTL during the follow up period. In all false positive cases, PTL was not detectable until the age of six months. Despite problems to be resolved, determination of urinary PTL titer is valuable for the detection of CAH patients. In addition, urinary PTL could be a good parameter for the further follow up of false positive cases in neonatal mass screening.

Sampling methods and residential factors affecting formaldehyde concentration in indoor air.

Formaldehyde (HCHO) is the most serious residential pollutant. In order to evaluate residential HCHO levels, two sampling methods have been recommended; one is a 30 minute sampling in a closed room, and the other is a 24 hour sampling with an ordinary lifestyle routine. The aim of this report was to clarify the difference between the HCHO levels obtained by the two sampling methods. Residential air in 58 rooms was sampled for 30 minutes by an active sampling method more than 5 hours after residents closed windows, and by a passive sampling method for 24 hours with an ordinary lifestyle routine. The HCHO concentration with the 30 minute sampling was 0.118+/-0.065 ppm (range: 0.034-0.295 ppm) and 36 rooms (62%) exceeded the Japanese guideline value of 0.08 ppm, while 5% were higher than 0.25 ppm. The HCHO concentration with the 24 hours sampling was 0.053+/-0.039 ppm (range: 0.02-0.167 ppm) and only 13 rooms (22%) exceeded 0.08 ppm. The relationship between the concentrations obtained by the two methods was linear. However, the level with the 24 hour sampling significantly reduced with prolonged window opening time, meaning that occupants made an effort to reduce the usual exposure to about 40% of the exposure in a closed room by opening windows in order to escape from irritation. Since major adverse effects of HCHO are irritation and sensitization, the occasional peak concentration must be focused. In order to evaluate residential HCHO levels, measurement in a closed room is recommended even if people are living there.

Substratum-bound elastin peptide inhibits aortic smooth muscle cell migration in vitro.

Migration of smooth muscle cells (SMCs) of the media through the internal elastic lamina to the intima in response to various chemoattractants is considered to be an important event in the development of atherosclerosis. We evaluated the influence of elastin peptides prepared from normal aorta on migration of cultured rat aortic SMCs in vitro. Studies with filters coated with elastin peptides in a modified Boyden's chamber showed that the migratory response of cultured rat aortic SMCs in response to platelet-derived factors was impeded by filter-bound elastin peptides. The inhibitory effect appeared to be relatively specific for elastin peptides and for SMCs, as other matrix components (Types I, III, IV, and V collagens and fibronectin) did not impede SMC migration, and polymorphonuclear leukocytes were not impeded by elastin peptides. Elastin peptides in solution in the lower well caused the migratory response, and this response was also inhibited by filter-bound elastin peptides. Attractants such as platelet-derived factors and elastin peptides are likely to be present in the matrix around migrating SMCs. These studies suggest that elastin peptides adhering to the substratum or elastin, a major component of elastic fiber, may be one of the natural inhibitors of vascular SMC migration in response to chemoattractants in the fluid phase.

[Surgical management of stab wound of the chest].

During the past three and half years, we experienced eighteen patients with stab wound of the chest. Ten patients were homicidal victims and the remainders were suicides. According to our indications (Table 4), thoracotomy was done in eight patients (44%). The major reason for thoracotomy in this series was massive bleeding. Five pulmonary, four diaphragmatic, four intercostal-artery's and two pericardial injuries were repaired. In our series, six patients (33%) were accompanied with abdominal stab wound and laparotomy was done in five patients. Four liver's one stomach's, one spleen's, one intestine's and one omentum's injuries were repaired. There were three DOA's (dead on arrival). The causes of DOA's were massive bleedings from the heart in two patients and from the liver in one patients. Except for the DOA's, four patients (27%) were not operated on. In conclusion, three DOA's, could not be resuscitated, but all remainders (the thoracotomy's, the laparotomy's and the non-surgical patients) survived and had no complications.